Benoit Delinchant

Gustavo Felipe
email: gustavofmn@hotmail.com

Martin Nascimento

Salman Muhammad
email: muhammad-salman.shahid@g2elab.grenoble-inp.fr

Shahid

Frédéric Wurtz
email: frederic.wurtz@g2elab.grenoble-inp.fr

Machine Learning on Buildings Data for Future Energy Community Services

Keywords: machine learning, energy flexibility, random forest, gradient boosting, auto-consumption, building consumption, PV forecast, energy communities

The decentralization of energy generation and transmission demand for the Internet of Energy with real-time peer-to-peer energy exchange. The intermittent renewable energy provides a challenge of consumption flexibility at consumer side. Buildings are significant in this new context, since they are the biggest energy consumer worldwide and can contribute to local renewable energy production as well. Therefore, proactive building services will be required in near future in order to operate energy community. This paper deals with energy flexibility obtained through PV production forecast for a community. Decision tree technique is applied on historical hourly data of 3 years for week-ahead forecast of building consumption, photovoltaic production, and for fault detection diagnostic. Feature engineering and energy expertise used to obtain good forecasting performances are discussed. The significance of these technics for prospective energy community service is also discussed in the paper.

I. BUILDINGS AS A PILLAR OF THE INTERNET OF ENERGY

Environmental policies and the reduction in production cost of renewable energy are transforming the energy landscape of cities and countries worldwide. The renewable energy is decentralized and intermittent in nature and due to its constraints, it modifies the role of transmission system operator (TSO) and distribution system operator (DSO) while connected to the energy grid. In this context, the role of DSO is becoming increasingly significant to keep the balance of energy flows for avoiding local congestion. In [START_REF] Giulietti | Smart Consumers in the Internet of Energy -Flexibility Markets and Services from Distributed Energy Resources[END_REF], the Center on Regulation in Europe highlights different proposals for DSO-TSO interactions that allow the trade of flexible services.

With the decentralization of energy network and implementation of Internet of Energy (IoE), each node of the energy network will be able to produce, consume and store energy. These real-time peer-to-peer exchanges constitute IoE revolution, and require a real paradigm shift in technological solutions and energy regulation. Today, the operators of the electrical networks are practically blind on the scale of the districts and can only through demonstrators sketch the potential of solutions to prepare the future [START_REF]European project[END_REF]. IoE will rely on net-metering to decide the dynamic electricity pricing; based on the available energy storage (kWh) it will also depend on the capacity (kW). Therefore, it accounts for strong time dependence. The complexity of pricing will no longer allow optimal human decision-making, rather a set of third-party players should be developed to implement advising and controlling services.

IoE is not only made up of smart grids; it is also comprised of the actors at each node of these grids. For instance, energy management at a local level should aim for a multi-objective optimum integrating economic constraints, environmental issues, and citizen choices. Self-consumption is a good way to involve consumers in energy system and to play on levers that the economic aspects could not reach. It permits to reduce transmission loss (8% on average), reduces the infrastructure investments and motivates the increase in consumption, particularly in cities. Legislation on collective selfconsumption is already in place in some countries like France [START_REF] Morriet | Multi-actor modelling for MILP energy systems optimisation: application to collective selfconsumption[END_REF], which encourages the citizens to play an active role in IoE. They can thus collectively produce and consume their own energy. However, it is required that these solutions that are promoting the penetration of renewable energies must be complemented by the services for operators and consumers (i.e. the occupants of buildings).

Residential and commercial buildings are the biggest energy consumer worldwide; mainly for their needs related to thermal comfort. They consumed more than 37% of final energy in OECD countries in 2017 on par with transport (37%) and ahead of industry (25 %) [START_REF]World energy balances: Overview[END_REF]. In perspective of decentralized production in proximity of load centre, energy production could be very strongly developed on these buildings in the coming years. The French Environment and Energy Management Agency (ADEME) proposed a scenario for a 100% renewable mix across France in 2050; where 34% of the capacity would be generated by photovoltaic panels on the rooftop of the buildings [START_REF] Artelys | A 100% renewable electricity mix? Analysis and optimisation exploring the boundaries of renewable power generation in France by 2050[END_REF]. According to this report, buildings flexibility will help up to 18% for managing the network balance of 100GW peak demand, essentially from heating, ventilation, air conditioning (HVAC) (14GW) and hot water tank (4GW).

Buildings are therefore essential in the energy transition [START_REF] Wurtz | Smart-Buildings" integrated in "Smart-Grids": a key challenge for the energy transition by using physical models and optimisation with a "human in the loop" approach[END_REF]. However, they must be able to communicate with each other and offer services to network operators or at the level of energy communities.

II. MACHINE LEARNING FOR BUILDING ENERGY SERVICES

As mentioned above, buildings must offer flexibility to ensure optimum energy management. Two such tools that might already be implemented in buildings are as follows:

 Optimization of the energy bill: by proposing an adaptive contract, based on the analysis of past data and long-term forecasts. This helps in notifying the consumer to avoid upcoming over-consumption through load shedding and hence to avoid financial penalties.

 Fault detection diagnosis and maintenance: it allows to detect a variation in the measurement compared to a baseline, indicating a potential malfunction.

In this paper, we will try to go further by expressing the needs for the implementation of new service tools for energy communities. The tools presented below may rely on the same technics already used for optimizing the energy bill or for diagnosis of a consumer, yet they need to be adapted for an energy community.

 Optimizing collective self-consumption: ensuring a balance between production and consumption at the community level through promoting the penetration of renewable energies.

 Energy flexibility: each building offers the means of quantifying the potential flexibility and activating negotiations for flexible actions to the community.

Predicted models must be deployed in order to make these services work. An approach is to develop physical models often resulting from specialized expertise and in-depth knowledge of the system to be modelled [START_REF] Dinh | Building Modelling Methodology Combined to Robust Identification for the Temperature Prediction of a Thermal Zone in a Multi-zone Building[END_REF].

Another way is to model physical system using artificial intelligence (AI). AI is now a thriving technology driven by the convergence of deep learning, and planetary-scale data. Its impact on human society is expected to be on a scale comparable to electricity. During 1975-1990, artificial neural network improved its performance by two innovations: multilayer perceptrons with soft decision surface and learning with back-propagation. However, since 2012, deep learning (DL) has been found effective to provide reliable solutions for longstanding problems [START_REF] Lan Goodfellow | Deep learning[END_REF]. Long short term memory (LSTM) is a recurrent neural network (RNN) dedicated to time series modelling which is able to catch different dynamics of the signal. This deep learning technique has been successfully applied for building hourly consumption prediction [START_REF] Marino | Building energy load forecasting using Deep Neural Networks[END_REF]. Support vector machine (SVM) is another machine-learning algorithm, which can be applied to predict building energy consumption [START_REF] Zhao | A review on the prediction of building energy consumption[END_REF]. Both of these technics are complex; notably with hyper-parameters to tune, with long time to train, and difficult to interpret. In this paper, we used a machine learning method based on decision trees, which has the advantage of being quick to calculate and easily interpretable.

The three most common barriers to AI are: (1) insufficient labeled data for learning, (2) insufficient computing power and (3) prohibitive cost of encoding domain knowledge. The barrier (2) is not addressed in this paper, but we are going to discuss on data availability and the link between domainspecific expertise which are required to build efficient AI.

To implement the proposed building services, it is required to create a forecasting model. The classical horizon for model predictive control is a day-ahead forecast, while in order to provide other kind of services for energy planning including human decision-making, we will study in the following section a week forecast modelling. Therefore, sufficient and reliable historical data is required to make a supervised learning model with the characteristics as follows.

 Data Length: it can be important to capture short term as well as long term dynamics, like the annual seasonality.

 Sampling Frequency: the choice of sampling frequency is according to the model requirement and the memory constraint of hardware. Any fine sampling which can be down-sampled for annual history is helpful in this regard.

 Data Quality: it is common to have missing data or outliers. In the case of missing data, an interpolation during the pre-treatment phase is helpful for a time series data, whereas certain technics can be used to detect and remove the outliers.

 Data Quantity and Diversity: a diverse and big data brings more choices of feature selection according to the needs of the predictive model. The features can be sorted according to the best correlations among the parameters.

To illustrate this, we are modelling consumption of the GreEn-ER building [START_REF] Wurtz | Smart-Buildings" integrated in "Smart-Grids": a key challenge for the energy transition by using physical models and optimisation with a "human in the loop" approach[END_REF], a 22,000 m² service building, accommodating 2,000 occupants, and massively monitored and controlled for energy efficiency. It has around 1500 connected sensors. The consumption of the building is mainly driven by the thermal comfort of the occupants and air quality. The historical consumption of a period of 3 years (from 2017 to 2019) is used for modelling. For the purpose of training the model, we will use the data of 2 years, while the last year will be used for model validation.

III. CONSUMPTION FORECAST AND FEATURE ENGINEERING

The first task of a modelling is the definition and selection of the features from the raw data (also called feature engineering). Features are the inputs of the prediction model. There are two categories of features to be selected for making a predictive model of the consumption of GreEn-ER. The first category of features is based on the historical raw data. Specifically, these are Date Time Features, Lag Features and Windows Features. A second category of features are the exogenous variables, which are correlated to the variable to predict. We briefly discuss these features by illustrating on the building consumption prediction.

A. Date Time Features

The Date Time features correspond to properties linked to the instants of the observations. For instance, the time of day helps to model the daily frequency and therefore helps to model daily events such as the automatic start of heating at 6 a.m., the arrival of staff at the office at 8 a.m., the lunch break etc. The day of week makes it possible to model working days and weekends. The day of year allows to take into account the seasons and holidays.

The well-known objective of machine learning is to adjust the bias-variance compromise in order to have a model which generalizes well the behaviour of the data, and which therefore leads to a robust prediction. For this, we need a model that reduces the bias but without leading to over-fitting (i.e. decision tree), and at the same time it ensures the smallest possible variance in the data without leading to under-fitting. To solve the problem of bias-variance, we can adopt an ensemble approach, that cuts training data into a set of smaller data sets (bootstrapping), performs several learnings and returns the average. This technique is known as Random Forest (RF) [START_REF] Ho | Random Decision Forests[END_REF]. RF has been compared in [START_REF] Waseem | Trees vs Neurons: Comparison between random forest and ANN for high-resolution prediction of building energy consumption[END_REF] with neural network for HVAC hourly consumption forecast, and the authors claim that for comparable performance, RF is easier to use. It has been used for automated measurement and verification before and after a retrofit (pre-retrofit and postretrofit data) and to predict how much energy the retrofit saved [START_REF] Raftery | Mave:software automated Measurement andVerification[END_REF]. RF has been also used for building consumption anomaly detection [START_REF] Araya | An ensemble learning framework for anomaly detection in building energy consumption[END_REF].

Comparing to conventional time series prediction methods such as SARIMA (Seasonal Auto-Regressive Integral Moving Average), learning methods based on RF show better performance if features are well studied [START_REF]Comparison of ARIMA and Random Forest time series models for prediction of avian influenza H5N1 outbreaks[END_REF].

The regression model defined with 100 estimators, takes only 4 seconds to be trained on a desktop computer for a historical data of 2 years at 1 hour sampling time, with 5 features. This makes a total of 87,600 entries in the historical data.

Fig. 1 shows the actual and predicted load curves for the building. The hourly mean error calculated for the whole year 2019 is 90kWh, which renders the model appropriate. Fig. 2 shows the features importance obtained after model training. The Day of Year feature explains half of the behaviour of the consumption, while Hour of Day is second important feature with 30% importance.

B. Lag Features

Lag features appear particularly for time series. They introduce the dependence of the current value on the past values. The downside of this feature is that it cannot be predicted, so the model prediction horizon becomes limited very quickly. If a 1 step lag shift is made and a model is trained on that feature, the model will be able to forecast 1 step ahead having observed current state of series. So, during the initial lag selection, a balance between the optimal prediction quality and the length of forecasting horizon has to be found. It can be observed by looking at the autocorrelation of the consumption data (Fig. 3) that a consumption value at a certain hour has a strong dependence on the previous hour (h-1) or the previous few hours (h-n, where n is number of hours), then a dependence on the consumption of the previous day at the same time (h-24). The consumption value at a certain hour also has a strong dependence on consumption at the same time in the previous week (h-168).

C. Windows Features and Exogeneous Variables

Windows feature is a summary of values over a fixed window of prior time steps. It can be for example the energy consumed the day before or the previous week (sum or average value), or the minimum and maximum values. The question that often arises concerns the optimal size of the sliding window. We can apply this technique to the series to be predicted directly, but for a week-ahead forecast, we must therefore look for statistical quantities of the week before.

We can also introduce exogenous features, i.e. signals correlated to the consumption, in particular the outdoor temperature. We can therefore apply window feature on this variable to obtain the average daily temperature. The prediction of this variable is relatively easy to access by weather forecast APIs like OpenWeather 1 . Fig. 4 shows temperature and consumption for the 4 seasons (spring, summer, autumn and winter). After training a model with windows features, the new feature explains more than 25% of the prediction. The improvement compared to the reference is 12% with an average error of 79kWh compared to 90kWh for the reference.

Finally, if we use the two previous features (Lag h-168 and outdoor mean temperature) in combination with the windows feature, the total improvement is 39% with an average error of 65kWh integrated over the year 2019. The weekly energy calculated from this last model, is integrated over the year and gives a value of 2215 MWh, compared to 2071 MWh in reality, which is 7% error.

In this model, the lag feature (h-168) has the highest importance with 60%, while with mean outdoor temperature, it is 16%, with Day of Year, it is 11%, with Hour of Day it is 8%, with Day of Week it is 3%, with Year it is 1% and with Holiday it is nearly 0% for the whole year. Though the last feature is insignificant, it is still important for some days like in Fig. 5 (8 th May: Holiday in commemoration of 2 nd world war armistice in 1945). Other important features can be directly found by physical expertise of the system. In addition to the outdoor temperature forecast, it would be interesting to provide the indoor set-point temperature as a feature for forecasting. This may, varies according to the modes programmed in the BMS (Building Management System). Additional heat gain (through the occupation of the building and the radiative contributions by the glazing) is also very important in modern well-insulated buildings, so it is desirable to have a prediction.

IV. PHOTOVOLTAIC PRODUCTION FORECAST AND HYBRID

DATA/PHYISCAL MODELLING New energy services for energy management and flexibility in the local energy community require energy production forecast.

There are many photovoltaic production prediction models, owing to the different prediction horizons: ultra-shortterm forecasting (a few minutes to 1 hour ahead), short-term forecasting (1 hour to several hours ahead), medium-term forecasting (several hours to 1 week ahead), and long-term forecasting (1 week to 1 year or more ahead), but also for different spatial scales (local or regional). For example, methods for micro-grids control using cameras will be on a local scale, in order to produce ultra-short-term forecasting [START_REF] Scolari | Modeling and Forecasting of Photovoltaic Generation for Microgrid Applications: from Theory to Validation[END_REF]. A quite common time scale concerns day-ahead photovoltaic forecasting. A. Nespoli present in its recent paper [START_REF] Nespoli | Day-Ahead Photovoltaic Forecasting: A Comparison of the Most Effective Techniques[END_REF] a comparison of most effective technics.

For larger horizons, we often face a strong uncertainty that local weather models seek to resolve. In [START_REF] Dung V Nguyen | Irradiance forecast model for PV generation based on cloudiness web service[END_REF], we developed a heuristic approach based on a prediction of nebulosity to obtain Direct Normal Irradiance (DNI) and Global Horizontal Irradiance (GHI) which are necessary for PV model. We propose here to use two specific features to train DNI, a physical model providing clear sky DNI as well as nebulosity prediction data provided by the APIs from Météo-France (AROME open data [START_REF]MeteoFrance -AROME Weather Forecast[END_REF]). Then the same can be done for GHI in order to obtain PV production forecast.

We proceed as for consumption to a learning by RF with 200 estimators, which takes 3 seconds to train. Fig. 6 is showing DNI for a week. RF prediction has an average error of 83.4 W/m², compared to 88.5 W/m 2 for the empirical model developed in [START_REF] Dung V Nguyen | Irradiance forecast model for PV generation based on cloudiness web service[END_REF]. Fig. 7 shows that the clear-sky model is the most important feature (34%), then Day of Year, Cloudiness and finally Hour of Day. This complementarity between data and physical model is one of the new challenges of cyberphysical modeling in the coming years. To conclude this part, powerful predictive models are easily achievable. The challenges are therefore now the development of services such as self-consumption at the scale of an energy community by exploiting these production and consumption forecasts.

V. INTERVAL PREDICTION FOR FLEXIBILITY CAPACITY

Beside auto-consumption, flexibiliy is another challenge for the energy communities. One of them can be the real time evaluation of flexible capacity. It corresponds to the power that can be shedded or over-consumed when the grid requires it to improve the auto-consumption ratio. The capacity of evaluation of flexibility is difficult, as it strongly depends on variation of normal comfort level among the occupants. In [START_REF] Pajot | Impact of Heat Pump Flexibility in a French Residential Eco-District[END_REF], [START_REF] Pajot | An Approach to Study District Thermal Flexibility Using Generative Modeling from Existing Data[END_REF] we have used physical based models in order to evaluate flexibility potential of district buildings that are heated and cooled by heat pumps. Here we are questioning machine learning technics in order to provide the same kind of information.

In addition, Fault Detection Diagnosis (FDD) allows realtime detection of inconsistent behaviour by identifying measures that would go beyond a standard range of variation. For instance, FDD has been already developed by [START_REF] Yan | Forecasting Building Energy Demand under Uncertainty Using Gaussian Process Regression: Fea-ture Selection, Baseline Prediction, Parametric Analysis and a Web-based Tool[END_REF] using Gaussian process regression.

We are applying on GreEn-ER consumption another regression technique, which is close to Random Forest (RF). Where RF manages the variance problem thanks to bootstrapping, it does not manage at best the bias introduced by the depth of the regression trees. A variant of RF called Gradient Boosting (GB) helps to better manage the bias. While RF generates random and independent trees in parallel, GB works sequentially to create new trees depending on the performance of the previous ones. In addition, optimization uses the gradient to accelerate convergence.

In order to create the prediction boundaries, two models are built. The first one uses 10% of the smallest data, and the second one 10% of the largest data (90% quantile). To train these models, we are using the same features as part III, with the outdoor temperature, but without the historical values (h-168). The models use 200 estimators and a maximum tree depth of 10. The 2 models are trained in 46 seconds.

To illustrate the FDD, Fig. 8 presents a measured consumption (black) that goes out of limits (min: blue, max: yellow) during the first week. Maintenance on the system is then carried out and the data returns to a normal state for the 2 nd week. An important remark can then be raised here, if the model takes too much account of the last measured values, like with Lag features, this kind of deviation is more difficult to identify. Indeed, the model will consider the anomalies as normal values with time. Does these intervals can help to evaluate the flexibility capacity by giving possible variations of consumption while keeping the building in a "normal" state ? To go further it will be required to study indoor comfort such as temperature modeling, but also put enough information on the data in order to be able to simulate with machine learning model, the heating or ventilation switch off consequences on the comfort.

CONCLUSIONS

In this work, we implemented different machine learning technics for predicting the consumption of a building, predicting photovoltaic production or even detecting faults.

We exploited the Random Forest (RF) and Gradient Boosting (GB) technics that are based on a set of decision trees offering good prediction performance in a short time and compatible with a hardware implementation. In addition, they offer good interpretability of results due to the possibility of exploring the decision tree, and due to information regarding the importance of feature. The feature engineering work was more particularly highlighted, and shown the need to introduce more exogenous features to implement richer correlations. An expertise in the functioning of the system is then necessary, as well as the provision of the richest possible data history with allowing to make the best choices according to the needs.

We have also shown on photovoltaic production, that it can be interesting to provide data from physical models (clear sky model), and therefore that the approach by data is not contradictory with a physical approach. Again, physical expertise is needed to define the features. These consumption and production prediction services must be the basis of future services developed for the energy community in order, for instance, to optimize the rate of self-consumption.

Finally, the prediction of intervals that can be used in FDD is rich information on potential deviations in consumption and gives a first approximation of the buildings flexibility capacities.

Fig. 1 .

 1 Fig. 1. One-week prediction using Random Forest, based on Date Time Features

Fig. 3 .

 3 Fig. 3. Autocorrelation function of consumption time serie, hourly steps The lag feature is very significant for the training of the model. It explains 65% of the prediction and then considerably reduces the dependency on the others. It implicitly includes information already present such as the Hour of Day or Day of Week. The result of the model is over-fitting, which leads to a poorer generalization of the model. Nevertheless, the integrated result for the year 2019 is improved by 16% with an average error of 75kWh compared to 90kWh previously.

Fig. 4 .

 4 Fig. 4. Pair plot and density distribution of consumption and temperature.

Fig. 5 .

 5 Fig. 5. Week prediction where a holiday is well forecasted even with nearly zero importance for holidays features.

Fig. 6 .Fig. 7 .

 67 Fig. 6. Random Forest DNI forecast based on nebulosity forecast and clear sky physical model.

Fig. 8 .

 8 Fig. 8. Fault Detection Diagnosis (FDD) using Gradient Boosting.

  SYMPOSIUM DE GENIE ELECTRIQUE (SGE 2021), 6 -8 JUILLET 2021, NANTES, FRANCE

TABLE I .

 I SUMMARY OF FEATURE SELECTION IMPROVEMENTS

		Refer ence	Lag (h-168)	Outdoor mean Temperature	Both
	MAE (kWh)	90	75	79	65
	Improvement (%)	-	16	12	39

a. Mean Absolute Error of Energy per hour


David Esteban

Clara Sandrini

CRH-

Our talk aims at comparing two very different situations. This comparison is possible because both cities were planned in the same time. These urban plannings gave rise to two districts of similar scale: Mirail in Toulouse and Luylin in Sofia. These two projects could not be realized as they had been conceived.

After a brief description of these two contexts, we will examine the urban design of these two neighborhoods, the production of the collective and the forms of participation of the inhabitants.

GEOGRAPHICAL AND POLITICAL SITUATION

Bulgaria is a country of the European Union, located in the Balkan Peninsula. Its capital is Sofia, located in the west of the country between two mountains bands, which give it a "bowl" appearance.

After the Second World War, the Bulgarian Workers' Party (POB) implemented a popular democracy in the wake of the Soviet Union. The industry is nationalized and developed and the soil becomes collective.

In this context, the city of Sofia is first of all the object of a reconstruction plan which is directly inspired by the city project elaborated by the German architect Mussman before the war. This project imagines the city as a garden city, with numerous parks, residential green spaces and a highly developed public transport network.

At the end of the 1950s, the country entered a process of industrialization of construction, led by the Soviet Union. The city of Sofia is then the object of an urban planning which foresses its extension by the construction of new autonomous districts, the gilos-rayons. These urban complexes are made up of several sectors, the micro-rayons.

However, the communist or socialist regime does'nt go back on the principle of individual ownership: housing is offered for purchase, but it is delivered unfinished to limit construction costs.

ZUP : Massive building opération

France is an occidental country. On the west of Europe, this country is composed by a veritable territory structure, that made by many processes. Toulouse is located in the southwest of France, far from Paris.

After the war, two paradigms have made the principal mind set build new housings: build it fast and low cost. If the principal interest was to resolve the lodgment crisis, it was also a double opportunity. The French state to make an big industry, and the urban designers introduce a new think of housing units.

After some years to experiment and to engage the massive production of housings, the French state by the principle of ZUP has allow some big town to think about their evolution. The final version of the Priority to Urban design Zone (ZUP) regroups every condition for an operation of housing: the possibility to buy the space and to make a project who contain at least 500 housings. The framework of the massive lodgment production is complete, but not without consequences.

Toulouse is considered like a metropolitan city since the law about the modernization of territory in 2014. This city has ever had some difficult follow the evolution of the French paradigm on the urban politics. But this period of modernization is one exception on the urban history of this metropolitan town.

The city was first modernized by the state, with the establishment of industries and the development of the airport. But Toulouse is still perceived as a rural area, whose limited extension was planned by Léon Jaussely in 1924. The think is completely axed on the center for his history, and the limitation of the urban extension on the capacities of the electricity and water network.

CITIES MODERN TOWN-PLANNING

At the beginnings of the 60's, the master plan drawn up by the architect Neykov proposes a hierarchical and sectorized vision of the city, with the establishment of gilo-rayons to the west, east and south. These housing complexes are located outside the old city limits. They are planned on the site of former agricultural villages. And, overall, this Neykov plan continues Mussman's planning with the creation of parks and gardens$ In the west, the creation of a huge district is implanted on the former village of Luylin.

This housing complex marks a real transition for the Bulgarian housing policy. Previously, housing construction was regulated by the state through design offices, but most of the investment in construction came from private funds, carried by citizen construction cooperatives. In the 1960s, the state invested itself in construction by public funds. The construction of housing became mass construction, with the application of prefabrication processes of concrete panels.

Thus is designed the Lyulin's gilo-rayon by Sofia design office (Sofproekt). The master plan is completed in 69 : the gilo-rayon is divided into eleven micro-rayons distributed around a cardo and a decumanus. Each building is built at 70% with prefabrication processes developed at the same time in Bulgarian factories. This project is representative of the research conducted on housing typologies. The Bulgarian architects were able to break away from the standards , by playing with volumes and spatial organizations.

The Mirial the urban exception in Toulouse urban history

In the same year of the creation of ZUP, Louis Bazerque has been elected. With a contemporizing thinking, he has modernized all of the city with the 1962 master plan. In the west, this master plan provides for the creation of the biggest housing units project on all urban history of Toulouse.

A contest was organized by Toulouse, to create by the ZUP a new town on the south west the historic center. The program was clear, the new urban piece should be a new administrative center and create 10 000 housing units on 700 hectares of field. The 31 January 1962, a team that lead by Candilis, Josic, and Woods was selected with a new concept of town.

Firsts sketches of the project was drawn around of a development of the principle of corridor for the housing unit, and the urban design. The Mirail had supposed to be the complement of the historic center. But contrary to this principle it appears like to another independent city.

The principles of the composition were:

 A circulations network that connects to the historical center  A sort of corridor slab that separate all type of mobility, and make a linear center  A composition that produces a strong density near to linear center, and some individual's lodgments on peripheric zone And to finish a framework of green spaces to include the principle of town country.

Composed by five districts, that all contain publics equipment to be independent, the connection between the new town and the history was weak. Unfortunately, the scale of the ambitions and the project that will increase all problematics that every common operation meet during their construction. That will product many modifications during the conception steps, and after during the construction.

THE EVOLUTIONS OF THE PROJECTS

During its construction, the Lyulin master plan continued to be redefined for each micro-rayon.

Construction began in 1973 and in 1977, the first three micro-rayons in the northwest were completed.

In this time, the project grew to 10 micro-rayons and the internal composition changed. The idea of the modern center disappears, as well as the sports facilities on the main axis. A green corridor appears to connect the centre to the Zapaden park in the south.

Since 1991, the infrastructure has continued to develop, especially to connect this housing complex to the rest of the city.

In addition, some areas have been taken over by private real estate development, such as Lyulin 8. This area, which is located on the north of the gilo-rayon, contains old self-buildings from the rural past. But it also includes dense private constructions, which are not connected to the various networks.

To the south, between Lyulin 6 and Lyulin 7, the "green corridor" has been replaced by a shopping center. Car dealerships stand next to supermarkets and there is only little space left for the original park.

History of renouncement

The project has been modified many times during the conception and also during the construction.

The scale of this project has aggravated all of problems that a classic project of construction, and the problems of collaboration and relationships between actors. The project has met some financial problems, and even if the relationship between the mayor and the urbanist's team is good, some conflicts have appeared with the team of technician team of the city.

Despite of that, the construction has begun in 1963, with "Bellefontaine" and "Reynerie" districts, and the firsts collectives housing unit. In 1966, the first inhabitants settle down.

But the financial problems become more and more important and product many difficulties on the process of the That push the design team to evolve and make choices. In front this situation, Alexi Josic has resigned. In 1967, a road diagram tried to resolve the permanents problematics of the city about the mobility. This plan has a real effect, some road loop destroys all principles of the initial concept: the linear city, and the continuity of slab and buildings in particularly. The project seems to disappear on the plan of 1972, its lost all of founding principles.

The municipality change in 1971. It marks the end of the era for the Mirail. Pierre Baudis has redirected all of means on the historic center and used only individual housing units on peripheries.

In 1975, the project did a real turning point to economics reflection. The ZUP was substituted by the ZAC that will be used for only for small pieces of the district. The individual housing units district of Pradette, and the economic place of Basso Combo has been achieved in total contradiction with the firsts initials concepts. The renouncement of urbans designers was complete and Candidilis quit the project in 1981.

THE PARTICIPATION OF THE INHABITANTS

As I said, Bulgaria had a special status in the bloc of "Eastern countries" with individual ownership.

The dwellings were delivered unfinished. And the inhabitants were left to choose the interior finishes, as well as the furniture, when they can find it. They are also owner of a small part of the exterior ground This double process engaged the inhabitants in a participation after of the construction. They have thus developed a socio-spatial organization for the management and maintenance of the common parts and exterior spaces. And, as time went by, they undertook renovations of the apartments, with more or less consultation with the other inhabitants. Thus, in Lyulin, the marges of the former greenway become places developed by the residents. On the side of Lyulin 6, they have extended the access roads to the housing and facilities. They also installed parking lots that form a threshold between the "commercial zone" and the residential spaces.

And in these residential spaces, as in all the city, the inhabitants take advantage of the open ground to grow vegetables. They create intermediate spaces that allow everyone to move into the collective space and to share it at differents times of day.

Participation against the erasure

Since the end of seventies, the Mirail was become a social district. In 1975, it became a political town of district. Even if some program like the Social development of district or the Social Urban development have added the subway in 1993, the Mirail has not changed until 2001.

After the years of renouncement come the days of rehabilitation. Like all these types of districts, many associations will be to develop to act against the social problems. But even if the Mirail and its university has built on a social mind set, the strategies launched were totally disconnected that social framework.

In the beginning of the millenary, a new paradigm appears in French law and the creation of ANRU (National Agency for Urban Renewal). In this mind set, in 2001 the Mirail is integrated to a contract that engages his renovation. The concept was to reintroduce the principle of the original master plan, but that will provoke the destruction of some part of tripode buildings. These destructions were problematics because il opposes the operational world to the point of view of the inhabitants about the size of the housing unit.

With the arrival of the left in power in 2008, the renovation project evolved. It was split into three parts and entrusted to different urban planners. Some experimentations are also beginning to work on the empowerment in the district, such as those conducted with the Toulouse School of Architecture. Another paradigm appears in 2014 with a law that allow a creation of inhabitant's corporation (les conseils citoyens) to participate on the rehabilitation project.

With these advances, the Reynerie project was able to evolve.

-The major project of the Maison de l'Image has been cancelled to make way for social housing.

-

The history of the Mirail has been highlighted and the last pieces of the slab have not been destroyed. -Shared gardens have been created at the foot of the buildings to allow residents to grow their own vegetables. -

The Reynerie park has become a water sports base for the inhabitants of Toulouse. And finally, a third place has been set up to develop these participative initiatives: the imaginations fertiles.

But the fight is not over because the Reynerie urban renewal project still envisages the destruction of a large part of the tripods. With another change of mayor the including of inhabitants is weak, and the participation stay desperately too only limited to an information about this part of the project.

CONCLUSION

To conclude, we would like to tell you about a result of the cross of these two researches. When we worked on the Reynerie in Le Mirail, we met with an elected municipal official, Mr Lagleize. We presented him the research carried out in Bulgaria. And as our discussions progressed, he was thinking of a new type of property. This gave rise to the Lagleize law, which dissociate land ownership from real estate ownership. This is a way for the creation of common spaces in France, with the involvement of citizens.


Guillaume Coiffier

Emmanuelle Ducasse

Arthur Keraudren

Emilie Prat

Hortense Modeste

Jean-David Albert

Olivier Loréal

Pascal Guggenbuhl

Anne Jolivet-Gougeon

Olivier Loreal

Anne Jolivet- Gougeon

Relevance of using both aerobic and anaerobic enrichment vials for optimizing rapid diagnosis of osteoarticular infections

Keywords: bone infection, blood vials, positive detection time, synovial fluid

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Bone and joint infections constitute a heterogeneous group of infectious pathologies including, among others, spondylodiscitis, prosthetic infections or septic arthritis, whose bacteriological evidence is essential for the proper management of the infection. Diagnosis is based on clinical, bacteriological, radiological and histological arguments, according to guidelines, such as the recommendations of the "Société de Pathologie Infectieuse de Langue Française" (SPILF) [START_REF] Societe De Pathologie | Recommendations for clinical practice. Osteo-articular infection therapy according to materials used (prosthesis, implants, osteosynthesis)][END_REF] or the "Infectious Diseases Society of America" (IDSA) [START_REF] Osmon | Executive summary: diagnosis and management of prosthetic joint infection: clinical practice guidelines by the Infectious Diseases Society of America[END_REF].

Bacterial identification is essential and prolonged cultures beyond 7 days are needed [START_REF] Schafer | Prolonged bacterial culture to identify late periprosthetic joint infection: a promising strategy[END_REF], especially for obligate anaerobic bacterial species [START_REF] Portillo | Propionibacterium acnes: an underestimated pathogen in implant-associated infections[END_REF]. An enrichment in liquid culture media [START_REF] Minassian | Use of an automated blood culture system (BD BACTEC) for diagnosis of prosthetic joint infections: easy and fast[END_REF] remains essential to allow growth of a low bacterial inoculum, particularly to facilitate the growth of obligate anaerobic bacteria, fastidious bacteria or "small colony variants".

Before inoculation into enrichment vials, a sonication step [START_REF] Portillo | Sonication versus vortexing of implants for diagnosis of prosthetic joint infection[END_REF][START_REF] Portillo | Improved diagnosis of orthopedic implant-associated infection by inoculation of sonication fluid into blood culture bottles[END_REF] or grinding [START_REF] Bemer | How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study[END_REF] has been recommended to improve sensitivity of bacterial detection.

In blood, after enrichment, the minimal microorganism concentrations required for blood culture vials flagged as positive, using BACTEC FX, were demonstrated >10 7 -10 8 colony forming units (CFU)/mL for most of the blood stream infection pathogens [START_REF] Wang | Early identification of microorganisms in blood culture prior to the detection of a positive signal in the BACTEC FX system using matrix-assisted laser desorption/ionization-time of flight mass spectrometry[END_REF]. For blood samples, the BACTEC FX systems yielded 100% positive signals with a minimal starting inoculum of 30 CFU/mL, whereas there were 8.1% (11/135) false-negative results at 5 CFU/mL [START_REF] Park | Comparison of Growth Performance of the BacT/ALERT VIRTUO and BACTEC FX Blood Culture Systems Under Simulated Bloodstream Infection Conditions[END_REF]. It is widely recognized that strictly aerobic bacteria are not -or poorlydetected in anaerobic vials, whereas obligate anaerobic bacteria are not -or poorlydetected in aerobic vials [START_REF] Messbarger | Role of Anaerobic Blood Cultures in Neonatal Bacteremia[END_REF]. These vials content additives to improve the level of detection, as lysing agents (e.g. saponin) [START_REF] Elliott | Improved recovery of antibiotic-stressed microorganisms on inclusion of saponin in aerobic blood culture media[END_REF] or resins (to trap some antibiotics) [START_REF] Spaargaren | Effectiveness of resins in neutralizing antibiotic activities in bactec plus Aerobic/F culture medium[END_REF][START_REF] Zadroga | Comparison of 2 blood culture media shows significant differences in bacterial recovery for patients on antimicrobial therapy[END_REF]. In bone or J o u r n a l P r e -p r o o f synovial samples (prosthetic or not), there are many studies demonstrating that the use of an enrichment step of the sample, by using blood vials, is necessary for optimizing diagnosis [START_REF] Alizadeh | Comparative Evaluation of Conventional and BACTEC Methods for Detection of Bacterial Infection[END_REF][START_REF] Rocchetti | Prospective study of the clinical performance of three BACTEC media in a modern emergency department: Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F[END_REF]. Despite some reports, showing the importance of enclosing the two types of vials (aerobic and anaerobic) for optimum positive detection time (PDT) in vials for blood cultures [START_REF] Passerini | Recovery and time to growth of isolates in blood culture bottles: comparison of BD Bactec Plus Aerobic/F and BD Bactec Plus Anaerobic/F bottles[END_REF], no study had proved the advantage to use one vial rather than the other, or both vials, for diagnosis of osteoarticular and prosthetic joint infections.

The aim of this study was to evaluate the advantage of using an aerobic or anaerobic enrichment vial, or both, to improve diagnostic performance of bone and joint infections, using the BD BACTEC FX instrumented blood system. This study was carried out with the aim of saving vials and technical staff time, while maintaining satisfactory quality and sensitivity criteria. The incubation duration (PDT) was recorded, for both aerobic and anaerobic vials inoculated with crushed bone or synovial fluid samples, and compared to standard culture method on agar media. The type of infection was not taken into account in this study, which is intended to be only a technical comparative study, aimed at defining the best performing media to detect bacterial growth as quickly as possible and thus ensure optimal management of the patient.

Material and Methods

Design of the study

A monocentric study was conducted at the University Hospital of Rennes (France).

Osteoarticular samples (synovial fluids and surgery bone samples) were prospectively collected by surgeons, rheumatologists or radiologists, during the diagnostic procedure.

J o u r n a l P r e -p r o o f

Synovial fluid as well as bone surgical specimens (crushed samples) were collected in sterile tubes (Nalgen®), compatible with the grinding step, and analyzed at the laboratory of Bacteriology. Before analysis, they were stored at room temperature for a maximum of two hours after collection. Practitioners have been, prior to the study, informed of the methods of analysis that would be implemented and the conditions necessary for collecting samples.

Synovial fluids and bone samples were then routinely analyzed at the laboratory of Bacteriology (University Hospital of Rennes, France).

Direct examination

Direct examination was performed, before crushing, directly on a smear of the specimen stained by Gram staining. An observation of the entire slide will be performed by an experienced technician for at least 10 minutes. A positive direct examination was defined as the detection of bacteria in at least two microscope fields.

Cultures

All samples were analyzed according to the microbiology laboratory's routine techniques, after grinding them, using a bead mill (Retsch® MM400 crusher: frequency 30.0/s, for two minutes and 30 seconds), as already described [START_REF] Bemer | How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study[END_REF].

In accordance with usual procedure, the time of positive growth on solid agar media [START_REF] Bemer | How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study[END_REF] was recorded: two 50-μl volumes were each spread onto a PolyViteX chocolate agar plate (BioMerieux) and incubated under a 5% CO2-enriched atmosphere for 3-5 days (to recover J o u r n a l P r e -p r o o f strictly aerobic and facultatively anaerobic bacterial species) and onto a blood agar plate incubated in an anaerobic atmosphere (Genbox anaer; BioMerieux) for 5 days (to recover bacterial species, obligate anaerobic and facultatively aerobic). All plates were daily inspected. All samples were also inoculated into a Schaedler broth (BBL™ Schaedler Broth, BD), which was inspected for 14 days. As soon as it became cloudy (or systematically on the 14th day), this medium was subcultured on a blood agar plate incubated (on an anaerobic atmosphere) and on a chocolate agar plate (on an aerobic atmosphere) for 48 h.

For each sample, 3mL of crushed sample were inoculated in each aerobic (BD BACTEC® Plus Aerobic/F)(BD-AE) and anaerobic (BD BACTEC® Lytic/10 Anaerobic/F)(BD-ANA) enrichment vials. As it has been widely demonstrated for blood cultures, and in order to improve the positive culture rate (and therefore the performance of the technique), the two blood culture bottles (aerobic and anaerobic) were systematically inoculated both (never alone).

Incubation was performed in automatic chambers for 10 days (BACTEC® FX, Becton Dickinson). For all positive vial cultures, the PDT (hours) was also recorded for vials who flagged positive by the automatic chamber of the BACTEC FX instrument.

Bacterial identification

Each bacterial species was identified from positive vial(s) of from a single colony by the MALDI-TOF mass spectrometry technique (Biotyper, Bruker) or from pure cultures by 16SrDNA PCR if necessary [START_REF] Bemer | Evaluation of 16S rRNA gene PCR sensitivity and specificity for diagnosis of prosthetic joint infection: a prospective multicenter cross-sectional study[END_REF][START_REF] Lallemand | Use of MALDI-TOF mass spectrometry after liquid enrichment (BD Bactec) for rapid diagnosis of bone and joint infections[END_REF]. Polymicrobial samples were excluded of the analyzed data, because they were too few to allow a satisfactory statistical analysis, and the interpretation of the results seemed more difficult with the data collected in this study. The qualitative variables are expressed in absolute number and percentage and their comparison was made by a chi-2 test (𝝌) or the exact Fisher test if one of the theoretical numbers in the contingency table was less than 5.

Results

Population studied

In this study, 46 bacterial species were identified from 496 samples (collected in 305 patients). Among the 496 samples, 246 were synovial fluids and 250 were crushed samples.

The different bacterial and fungal species identified, taking into account all cultural media, were Staphylococcus (aureus and Coagulase negative Staphylococci, CNS), Streptococcus (S.pyogenes, S.agalactiae, S.dysgalactiae, S.anginosus, S bovis complex, S.pneumoniae, S. gordonii, S. oralis, S. mitis, S. salivarius), Enterococcus sp., Cutibacterium acnes, Enterobacteriaceae (E.coli, K. oxytoca, Enterobacter sp., Pantoea agglomerans, Citrobacter J o u r n a l P r e -p r o o f freundii, Serratia marcescens, Morganella morganii), Campylobacter fetus, Pseudomonas aruginosa, Neisseria gonorroheae, and C. tropicalis or M. abscessus. Mycobacterium abscessus (n=1) and Candida tropicalis (n=1), were detected once (Figure 1). Identification was made for all microorganisms, without distinction of patient diseases, from all synovial or crushed samples. Microorganisms were collected and identified as soon as a bacterial culture was detected in at least one culture medium (solid or liquid).

Direct examination

Direct examination by Gram stain was positive and always concordant with results of bacterial cultures for 99/496 isolates (20.0%) (51/305 patients; 16.7%): 56/246 (22.8%)(for synovial fluid) and 43/250 (17.2%) (for surgery samples).

Recovery rate and percentage of microorganisms according to culture media (Table 1)

Recovery rate and percentage of microorganisms identified was tested in BD-AE and BD-ANA as enrichment vials, and in agar media.

C. acnes was the most frequently anaerobic commensal bacteria isolated in osteoarticular infections [START_REF] Portillo | Propionibacterium acnes: an underestimated pathogen in implant-associated infections[END_REF], and a significant difference was observed between the two vials for the anaerobic species C. acnes, better recovered in anaerobic vial (93% of cases versus 11.9% in aerobic vials) (p<0.001). A better recovery was also observed in aerobic vial compared to anaerobic vials for Staphylococcus sp. (p=0.03), Enterobacteria (p=0.03) and other Gram negative bacteria (p=0.01). Some strains were only identified from aerobic vials (15.5%)(S. sanguis), indicating the importance of using both atmosphere conditions for optimal PDT . As expected, the obligate anaerobic species were found preferentially in the anaerobic vials and the strictly aerobic species were found preferentially in the aerobic vials.

A better recovery was observed for all tested bacteria in Lytic/10 Anaerobic/F vials, compared to agar media. By comparing the growth time in Plus Aerobic/F vials compared to agar media, only Staphylococcus spp. grew significantly faster in Plus Aerobic/F medium.

Only 2.6% of bacteria have been identified only on agar media, with a small number of colonies (< 10 UFC/plate): C. acnes (n=1), S. aureus (n=4), S. hominis (n=1), S. warneri (n=3), S. epidermidis (n=2), S. dysgalactiae (n=1), and S. pyogenes (n=1). Among those, only two species were both positive by direct examination and/or combined to positive blood cultures (S. dysgalactiae and S. pyogenes.), but in all the other cases, a contamination was widely suspected and compatible with clinical data.

Positive detection time (PDT)

Detection time according to the type of sample (synovial fluid and crushed samples)

All bacterial species combined, the PDT was 13h [START_REF] Bemer | How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study[END_REF][START_REF] Wang | Early identification of microorganisms in blood culture prior to the detection of a positive signal in the BACTEC FX system using matrix-assisted laser desorption/ionization-time of flight mass spectrometry[END_REF][START_REF] Park | Comparison of Growth Performance of the BacT/ALERT VIRTUO and BACTEC FX Blood Culture Systems Under Simulated Bloodstream Infection Conditions[END_REF][START_REF] Messbarger | Role of Anaerobic Blood Cultures in Neonatal Bacteremia[END_REF][START_REF] Elliott | Improved recovery of antibiotic-stressed microorganisms on inclusion of saponin in aerobic blood culture media[END_REF][START_REF] Spaargaren | Effectiveness of resins in neutralizing antibiotic activities in bactec plus Aerobic/F culture medium[END_REF][START_REF] Zadroga | Comparison of 2 blood culture media shows significant differences in bacterial recovery for patients on antimicrobial therapy[END_REF][START_REF] Alizadeh | Comparative Evaluation of Conventional and BACTEC Methods for Detection of Bacterial Infection[END_REF][START_REF] Rocchetti | Prospective study of the clinical performance of three BACTEC media in a modern emergency department: Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F[END_REF][START_REF] Passerini | Recovery and time to growth of isolates in blood culture bottles: comparison of BD Bactec Plus Aerobic/F and BD Bactec Plus Anaerobic/F bottles[END_REF][START_REF] Bemer | Evaluation of 16S rRNA gene PCR sensitivity and specificity for diagnosis of prosthetic joint infection: a prospective multicenter cross-sectional study[END_REF][START_REF] Lallemand | Use of MALDI-TOF mass spectrometry after liquid enrichment (BD Bactec) for rapid diagnosis of bone and joint infections[END_REF][START_REF] Roux | Diagnosis of prosthetic joint infection by beadmill processing of a periprosthetic specimen[END_REF][START_REF] Calderaro | Higher recovery rate of microorganisms from cerebrospinal fluid samples by the BACTEC culture system in comparison with agar culture[END_REF][START_REF] Hughes | Microbiological diagnosis of prosthetic joint infections: a prospective evaluation of four bacterial culture media in the routine laboratory[END_REF][START_REF] Gain | Use of a pair of blood culture bottles for sterility testing of corneal organ culture media[END_REF] in BD-AE , 15h [9-30] BD-ANA, and 24.0h [24-48] on agar media, attesting a faster detection in BACTEC® vials (p<0.001) (Table 2). No difference was observed between the two types of samples, synovial fluid and J o u r n a l P r e -p r o o f crushed samples (p>0.05). In BD-AE, the PDT was 12.0h [7.3-18.1] from synovial fluid and 13.5h [9.1-24.1] from crushed samples. In BD-ANA, the PDT was 13.2h [7.2-28.0] from synovial fluids and 16.0h [9.9-31.0] from crushed samples. On agar media, the detection was possible from 24.0h [24-48] of incubation from synovial fluid or crushed samples.

Detection time according to direct examination

The PDT was always significantly lower when the direct examination of the sample was positive: the PDT was 6.6h [5.2-10.5] in BD-AE, 8.4h [5.2-14.2] in BD-ANA and 24.0h [24-24] on agar media. When direct examination was negative, the time of detection was 15.4h [10.4-27.2] in BD-AE, 17.6h [11.1-37.1] in BD-ANA and 24h [24-48] on agar media.

Detection time according to species and culture atmosphere (Table 2)

All strictly aerobic or facultative aerobic organisms were detected within 43.8h and 30h in BD-AE vials and BD-ANA vials, respectively. For an incubation period ≤ to 24h, 77.6% of the BD-AE vials versus 75.2% of the BD-ANA vials were detected positive by the automated system. Following a 48h-period of incubation, 93.1% of BD-AE vials and 86.4% of BD-ANA vials were positively detected. After 144 hours of incubation, only 2.3% of the BD-ANA vials were still detected positive by the automatic chamber. Number of isolated species identified from BD-AE and BD-ANA vials, with their PDT was described in Figure 1 acnes, n = 2; Staphylococcus sp., n = 2). In conclusion, we can therefore notice that obligate anaerobic species grow later, as expected, and preferentially in anaerobic vials, but after 10 days of incubation, cases of contamination are most often observed.

Detection time according to the type of medium used (aerobic and anaerobic vials and agar media)

The comparison of PDT of bacteria (all species combined) from BD-AE and BD-ANA enrichment vials, versus agar media were shown in Table 3. The PDT was always significantly shorter in vials than on agar media (p<0.001) for almost all species studied. C. acnes were detected, in 240h [67. (n = 5) in aerobic vials, 126h [99-183.75] (n = 40) in anaerobic vials and in 84h [24-102] (n = 6) on agar media (that was considered not significantly different; p=0.345). However, this surprising result must be considered with circumspection. It should be noted that out of the 6 cases where C. acnes was only detected on agar, only 2 were confirmed infections according to clinical and radiological criteria, and in other cases agar contamination could be suspected. M. abscessus was only detected in aerobic vials before a 92h-incubation time, and C. tropicalis was only detected in vials (aerobic PDT=11h and anaerobic PDT=23.5h).

J o u r n a l P r e -p r o o f

Discussion

The purpose of this study was to evaluate the benefit of enrichment using a single aerobic or anaerobic vial, while maintaining the diagnostic performance of bone and synovial infections, and in the hope of saving technical time and money. For both aerobic and anaerobic vials, the PDT required for diagnosis of bone and joint infections, was significantly shorter than on agar media, and most of the time was less than 144h. The optimal PDT in the two vials was variable according to the microorganisms, showing the interest in using both aerobic and anaerobic vials to optimize the speed of diagnosis.

Direct examination has been recognized as insensitive, with positivity rates between 10 and 30% [START_REF] Lallemand | Use of MALDI-TOF mass spectrometry after liquid enrichment (BD Bactec) for rapid diagnosis of bone and joint infections[END_REF], that was confirmed by this work. The use of sterile beads to crush the samples is known to improve the recovery rate of bacteria from prosthetic joint samples up to 83.7% (instead of 60.8% in case of culture without grinding), with a contamination rate of 8.7% [START_REF] Roux | Diagnosis of prosthetic joint infection by beadmill processing of a periprosthetic specimen[END_REF]. Some authors used sonication method and found a sensitivity of 100% by inoculation of sonication fluid in blood culture bottles, significantly higher than conventional sonication fluid (87%) or intraoperative tissue cultures (59%) [START_REF] Portillo | Improved diagnosis of orthopedic implant-associated infection by inoculation of sonication fluid into blood culture bottles[END_REF]. But although cases of contaminations have been reported using this method, no study has been done to compare the performance of sonication versus grinding. [START_REF] Bemer | How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study[END_REF] demonstrated the benefit of using vials rather than agar plates for diagnosis of OAIs. They showed a positivity rate of 69% on chocolate agar plate, 70.1% on blood agar plate, 68.8% in Schaedler anaerobic broth medium and 83% in BACTEC® blood culture vials, which is in accordance with our results. Today, culture media and preprocessing of samples are therefore powerful enough to detect the majority of bacterial species responsible for bone and joint infections. However, the PDT must also to be J o u r n a l P r e -p r o o f taken into account, especially during septic arthritis where the patient care needs to be as fast as possible, and in case of surgical revision requiring a rapid therapeutic adjustment. However, there is a limit to the value of this early detection: rapid clinical management must therefore be in line with this improved bacteriological detection. The responsiveness of clinicians must be optimal, in order to guarantee the initiation of antibiotic treatment as soon as possible, treatment which can then be guided by a reliable identification, more sensitive than a simple direct examination, and faster than cultures on agar media. Although the growth time in a bottle can often require more than ten hours, this method is still widely used, because it allows to then study the susceptibility of isolated bacteria to many various antibiotics, which is not yet the case in routine today with rapid detection tests (e.g. by PCR or NGS), carried out on sample vials. Moreover, in some cases during collection, PCR inhibitors may also be contained in the blood or synovial fluid added. Enrichment of the culture of osteoarticular specimens and the need for prolonged incubation has been widely demonstrated for optimum detection. Some published works showed that Anaerobic Lytic/F vials were used preferentially to Plus Anaerobic/F vials, because the recovery rate of bacteria and yeast was demonstrated significantly better than in the Plus Anaerobic/F vials, while performance of Plus Aerobic/F vials and Anaerobic Lytic/F vials was equivalent [START_REF] Rocchetti | Prospective study of the clinical performance of three BACTEC media in a modern emergency department: Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F[END_REF].

Bemer et al. and the CRIOGO group

Eliott et al. [START_REF] Elliott | Improved recovery of antibiotic-stressed microorganisms on inclusion of saponin in aerobic blood culture media[END_REF] showed that significantly more Gram-positive organisms (P<0.05) and Gramnegative organisms (P<0.05), including Enterobacteriaceae (P<0.05) were recovered from the lytic medium. An incubation of 14 days has been recommended [START_REF] Schafer | Prolonged bacterial culture to identify late periprosthetic joint infection: a promising strategy[END_REF], but without the use of blood culture vials as enrichment media. The use of blood culture vials has been shown to reduce incubation time to less than 14 days, with a good recovery of most of pathogenic bacteria as attested by sub-culturing of negative samples [START_REF] Schafer | Prolonged bacterial culture to identify late periprosthetic joint infection: a promising strategy[END_REF][START_REF] Minassian | Use of an automated blood culture system (BD BACTEC) for diagnosis of prosthetic joint infections: easy and fast[END_REF]. BACTEC® vial enrichment has J o u r n a l P r e -p r o o f already been tested for different samples, such as cerebrospinal fluid samples [START_REF] Calderaro | Higher recovery rate of microorganisms from cerebrospinal fluid samples by the BACTEC culture system in comparison with agar culture[END_REF] with a better recovery of 95.8% versus 53.3% on agar media). Hugues et al. [START_REF] Hughes | Microbiological diagnosis of prosthetic joint infections: a prospective evaluation of four bacterial culture media in the routine laboratory[END_REF] analyzed samples from prosthetic joint revision surgery, and showed that automated BACTEC® culture was the most sensitive method (87%), as compared with cooked meat enrichment broth (83%), fastidious anaerobic broth (57%) and direct plates (39%); all were highly specific (97-100%).

Another problem concerning the bacteriological diagnosis is the late growth that must be attributed either to a contamination (at the time of the sampling or at the laboratory) or either to a weak initial inoculum (chronic infection, antibiotherapy ...). The contamination rate was estimated at 2.2% with agar media. With vials this was more difficult to assess, because only C. acnes strains were identified after 144h of incubation, and it remained unclear whether this was a case of contamination or whether it was a chronic infection, undiagnosed by the other available criteria of infection. In our study, 2.6% of bacteria have been identified only on agar media, with a small number of colonies (< 10 UFC/plate), and among those, only two species were both positive by direct examination and/or combined to positive blood cultures (S. dysgalactiae and S. pyogenes.). In all the other cases, a contamination was widely suspected and compatible with clinical data. To confirm or invalidate this hypothesis of contamination, a 16S rRNA gene amplicon sequencing could be carried out on the crushed material. This would make it possible, in the event of a concordant result, to exclude an agar plate contamination and provide an additional argument for a torpid infection with a weak bacterial inoculum. Multiplying the number of culture media and collecting at least 4 specimens for surgical sampling facilitates microbiological interpretation and make it easier to suspect cases of contamination. The use J o u r n a l P r e -p r o o f of 16S rRNA gene amplicon sequencing should only be used when cultures are not sufficient to establish the diagnosis, due to a low sesnitivity [START_REF] Bemer | Evaluation of 16S rRNA gene PCR sensitivity and specificity for diagnosis of prosthetic joint infection: a prospective multicenter cross-sectional study[END_REF].

Regarding the PDT of blood culture vials, for sterility testing of corneal organ culture media, Gain et al. [START_REF] Gain | Use of a pair of blood culture bottles for sterility testing of corneal organ culture media[END_REF] estimated that 78% of blood culture vials were detected within 24 hours and 94% within 48 hours, which joins our results. Average detection time in the lytic medium was 15.8 h, compared to 22.7 h in the other medium (P<0.001) [START_REF] Elliott | Improved recovery of antibiotic-stressed microorganisms on inclusion of saponin in aerobic blood culture media[END_REF]. Minassian et al. [START_REF] Minassian | Use of an automated blood culture system (BD BACTEC) for diagnosis of prosthetic joint infections: easy and fast[END_REF] showed that the respiratory atmosphere of the inoculated blood culture vial influenced the detection of microorganisms: Staphylococci, Streptococci, Enterococci and Enterobacteriaceae were found in both aerobic and anaerobic vials, whereas obligate anaerobic bacteria (including C. acnes) only grew in anaerobiosis, and Pseudomonas grew almost exclusively in aerobic vials. Previous work showed that enrichment in vials can be more effective in detecting C. acnes [START_REF] Bemer | How Many Samples and How Many Culture Media To Diagnose a Prosthetic Joint Infection: a Clinical and Microbiological Prospective Multicenter Study[END_REF], but these authors used in their study pediatric vials, whose composition is different from the vials used in our study. This could explain, at least in part, this difference in results. Our study showed the advantage of using a set of two vials (aerobic and anaerobic) to improve the rapidity of diagnosis.

Conclusions

Using both aerobic and anaerobic vials, a large majority of bacterial species were identified after only 24 hours of incubation and often less. In addition, the use of MALDI-TOF to directly identify bacteria/yeasts on enrichment media has also saved valuable time for diagnosis. In 15.5% of cases, some microorganisms were only identified from aerobic vials and in 12.7% from anaerobic vials, indicating the importance of using both atmosphere conditions for optimal PDT. The enrichment media can improve the PDT by reducing it to a J o u r n a l P r e -p r o o f few hours, but the benefit of this rapid detection will be real only if the results are available continuously for the clinician and if a therapeutic management is immediately conducted.

Comparison between positive detection time in BD BACTEC® Plus Aerobic/F)(A) and anaerobic (BD BACTEC® Lytic/10 Anaerobic/F)(B) enrichment vials, with agar media.

Only positive samples, both on enrichment vials and agar plates, were counted (Aerobic n = 394; Anaerobic n= 347).

2 . 5

 25 J o u r n a l P r e -p r o o f Statistical analysis Statistical analysis was performed with SPSS 20.0. P< 0.05 was considered significant. Gaussian distribution for continuous quantitative were checked by the Kolmogorov-Smirnov test. No continuous quantitative variables (age and time detection on Bactec or agar support) were showed. So, continuous quantitative were expressed as median ± interquartile deviation (IQR). The comparison of these variables was performed by a Mann-Whitney nonparametric U test (k = 2) or by a Fiedman nonparametric ANOVA (k > 2).

  aureus, CNS, Bacillus licheniformis, Corynebacterium striatum, Enterobacter cloacae, J o u r n a l P r e -p r o o f Escherichia coli, Klebsiella oxytoca, Micrococcus luteus, Moraxella catarrhalis, Mycobacterium abscessus, Pantoea agglomerans, Pseudomonas aeruginosa, Neisseria gonorrhoeae), or from anaerobic vials (12.7%) (C. acnes, S. epidermidis, S. aureus, S. hominis, S. capitis, C. fetus, Lactobacillus sp, Finegoldia magna, Clostridium paraputrificum, S.

  . No Enterobacteriaceae, Campylobacter, Pseudomonas, Neisseria or Moraxella was detected after 48h and 72h incubation from BD-AE and BD-ANA vials, respectively. Between 96 and 144 hours of incubation, only 4 BD-AE vials were detected positive (Staphylococcus sp., n = 3; Actinomyces, n = 1), while 20 BD-ANA vials were detected positive (C. acnes, n = 12; J o u r n a l P r e -p r o o f Staphylococcus sp. n = 8). Beyond 144h of incubation, only 3 BD-AE vials came out positive from the automatic chamber (C. acnes n = 3), against 27 BD-ANA vials (C. acnes, n = 19; Staphylococcus sp., n = 6; Streptococcus, n = 1; Bacillus, n = 1). Beyond 240h of incubation, no BD-AE vials came out positive from the automatic chamber, against 4 BD-ANA vials (C.

Figure 1 .

 1 Figure 1.

Figure 1

 1 Figure 1.

Table 1 Number of isolates Gold- standard Recovery rate (%)

 1 P-value for comparison between Lytic/10 Anaerobic/F vials and Agar media c P-value for comparison between Plus Aerobic/F vials and Lytic/10 Anaerobic/F vials

				Plus		Lytic/10
			Agar media	Aerobic/F vials	P a	Anaerobic/F vials	P b	P c
	Staphylococcus sp.	311	303 (97.4)	278 (89.4)	0.006	259 (83.3)	< 0.001	0.03
	S. aureus	178	177 (99.4)	166 (93.3)	0.003	155 (87.1)	< 0.001	0.05
	CNS	133	126 (94.7)	112 (84.2)	0.006	104 (78.2)	< 0.001	0.21
	Streptococcus sp.	58	57 (98.3)	55 (94.8)	0.62	48 (82.8)	0.008	0.07
	Cutibacterium acnes	43	6 (14)	5 (11.9)	0.99	40 (93)	< 0.001	< 0.001
	Enterobacteriaceae	43	42 (97.7)	41 (95.3)	0.99	34 (79.1)	0.02	< 0.05
	Other Gram negative
		21	19 (90.5)	18 (85.7)	0.99	9 (42.9)	0.003	0.01
	bacteria
	All species	496	434 (87.5)	413 (83.2)	0.06	399 (80.4)	0.002	0.25
	CNS: Coagulase Negative Staphylococci

a P-value for comparison between Plus Aerobic/F vials and Agar media b J o u r n a l P r e -p r o o f

Table 2 462

 2 Positive detection time (h)

	Plus Aerobic/F	Lytic/10 Anaerobic/F
		Agar media	p
	vials	vials

Table 3 A Positive detection time on Agar media

 3

		24h	48h	72h	96h	120h	> 144h
	≤ 24h	244 (61,9%) 39 (9,9%) 14 (3,6%) 3 (0,75%) 4 (1%) 2 (0,5%)
	Positive
	detection
	time in
	Aerobic
	vials

J o u r n a l P r e -p r o o f

Acknowledgments

We thank Adina Pascu for helping us to format the manuscript. We thank Vincent Driano and Elise Recalt for their occasional help in collection of data.

Fundings

No funding

Conflict of interest

The authors declare that they have no conflict of interests regarding this study.

List of Tables and Figures

Table 1.

Recovery rate and percentage of main microorganisms identified in (BD BACTEC® Plus Aerobic/F) and anaerobic (BD BACTEC® Lytic/10 Anaerobic/F) enrichment vials, and agar media, attested by a positive detection time (vials) or growth on agar plate, during an incubation period of 10 days for vials and 5 days for plates (for the remaining day-incubation period the Schaedler agar broth was monitored and subcultured, if cloudly or systematically on the 14th day, on an anaerobic blood agar plate and aerobic chocolate agar plate). Other Gram-negative bacteria: Campylobacter fetus, Pseudomonas aeruginosa, Neisseria gonorrhoeae, Moraxella catarrhalis.

Table 2.

Positive detection time of the main micro-organisms in (BD BACTEC® Plus Aerobic/F)(AE) and anaerobic (BD BACTEC® Lytic/10 Anaerobic/F)(ANA) enrichment vials, compared to agar media. Other Gram negative bacteria: Campylobacter fetus, Pseudomonas aeruginosa, Neisseria gonorrhoeae, Moraxella catarrhalis. CNS: coagulase negative staphylococi. Table 3 J o u r n a l P r e -p r o o f


Michel Mitov

Pierre Sixou

Trapping of field-induced liquid crystalline structures by a polymeric network

Trapping of field-induced liquid crystalline structures by a polymeric network


Quentin Beuguel

ORCID Evgueni Kirillov

Jean-François Carpentier

ORCID Sophie M Guillaume
email: sophie.guillaume@univ-rennes1.fr

Upgrading Toughness and Glass Transition Temperature of Polydicyclopentadiene Upon Addition of Styrene-Ethylene-Butylene-Styrene Thermoplastic Elastomer

Keywords: Polydicyclopentadiene (PDCPD), Styrene-Ethylene-Butylene-Styrene (SEBS), Ring-Opening Metathesis Polymerization (ROMP), thermoplastic elastomer (TPE), mechanical and thermal properties

Polydicyclopentadiene (PDCPD) thermoset, as commonly prepared by ring-opening metathesis polymerization (ROMP), features excellent mechanical, thermal and anti-corrosion properties, but lacks ductility and toughness. In situ addition of 2 to 8 wt% of Styrene-Ethylene-Butylene-Styrene (SEBS) thermoplastic during material preparation slightly alters the stiffness while improving its toughness and ductility. Remarkably, 4wt% SEBS increases PDCPD glass transition temperature T g up to 165 °C (i.e. + 7 °C). Calorimetric analyses suggest that addition of SEBS, acting as a plasticizer during molding, reduces the polymerization time of DCPD. This result offers a simple method to adjust PDCPD impact properties and to increase its T g .

Since the elucidation of the ring-opening metathesis polymerization (ROMP) mechanism by Hérisson and Chauvin in 1971, 1 olefin metathesis catalysis for cycloolefin polymerization has been considerably developed. [2][START_REF] Buchmeiser | Homogeneous Metathesis Polymerization by Well-Defined Group VI and Group VIII Transition-Metal Alkylidenes: Fundamentals and Applications in the Preparation of Advanced Materials[END_REF][START_REF] Sutthasupa | Recent Advances in Ring-Opening Metathesis Polymerization, and Application to Synthesis of Functional Materials[END_REF][START_REF] Abera Tsedalu | A Review on Olefin Metathesis Reactions as a Green Method for the Synthesis of Organic Compounds[END_REF] Among the variety of materials thus prepared, polydicyclopentadiene (PDCPD) has appeared as one of the most interesting thermosets, [START_REF] Kovačič | Ring-Opening Metathesis Polymerisation Derived Poly(Dicyclopentadiene) Based Materials[END_REF] thanks to its high chemical and corrosion resistance, stiffness, and heat resistance for automotive, pipeline and building applications. [START_REF] Camboa Sá | Development of Lightweight and Cost-Efficient Exterior Body Panels for Electric Vehicles[END_REF][START_REF]Global Polydicyclopentadiene (PDCPD) Market Size 2021 Industry Share, Business Strategies, Growth Analysis, Regional Demand, Revenue, Key Manufacturers and 2025 Forecast Research Report Says Industry Research Biz[END_REF] Investigation of the polymerization mechanism of dicyclopentadiene (DCPD) revealed that the higher ring-strained norbornene first opens, resulting in the formation of a linear structure, followed by opening of the cyclopentene ring, ultimately resulting in a crosslinked network. [START_REF] Fisher | Ring-Opening Metathesis Polymerization of Exo-Dicyclopentadiene: Reversible Crosslinking by a Metathesis Catalyst[END_REF] Also, in the presence of ruthenium catalysts, PDCPD mainly crosslinks through metathesis but olefin addition reactions may also contribute to the crosslinking process, as reported by Davidson et al.. [START_REF] Davidson | Polymerization of Dicyclopentadiene: A Tale of Two Mechanisms[END_REF][START_REF] Davidson | The Polymerization of Dicyclopentadiene: An Investigation of Mechanism[END_REF] In addition, much effort has been devoted to control the polymerization kinetics of DCPD in reaction injection molding process, [START_REF] Yao | Ring-Opening Metathesis Copolymerization of Dicyclopentadiene and Cyclopentene through Reaction Injection Molding Process[END_REF][START_REF] Kim | Optimization and Analysis of Reaction Injection Molding of Polydicyclopentadiene Using Response Surface Methodology[END_REF] leading to a highly crosslinked polymer with high thermal resistance, characterized by a glass transition temperature T g close to 160 °C. Due to the absence of non-covalent interactions (e.g. hydrogen bonding) in the PDCPD network and to its propensity to form nanoscale voids, PDCPD has revealed remarkable impact performances much better than those of epoxy-based resins. [START_REF] Knorr | Overcoming the Structural versus Energy Dissipation Trade-off in Highly Crosslinked Polymer Networks: Ultrahigh Strain Rate Response in Polydicyclopentadiene[END_REF][START_REF] Long | Influence of Molecular Weight between Crosslinks on the Mechanical Properties of Polymers Formed: Via Ring-Opening Metathesis[END_REF] However, the quasi-static mechanical properties of PDCD and the lack of ductility, are very far from those reported for crosslinked elastomers, for example in terms of elongation at break. This is yet a drawback for many applications such as body panels or field joint coating. The use of comonomers (e.g. cyclooctadiene, alkyl-norbornenes) [START_REF] Yang | Cure Kinetics and Physical Properties of Poly(Dicyclopentadiene/5-Ethylidene-2-Norbornene) Initiated by Different Grubbs' Catalysts[END_REF][START_REF] Boggioni | Terpolymerization of Substituted Cycloolefin with Ethylene and Norbornene by Transition Metal Catalyst[END_REF][START_REF] Dean | Rapid Synthesis of Elastomers and Thermosets with Tunable Thermomechanical Properties[END_REF] or elastomers (e.g. polybutadiene, [START_REF] Yang | Curing Study of Dicyclopentadiene Resin and Effect of Elastomer on Its Polymer Network[END_REF] ethylenepropylene-diene (EPDM) monomer (< 5wt%) [START_REF] German | Physico-Mechanical Characteristics of the PDCPD-EPDM-30 Composites[END_REF] ), forming copolymers with possibly pendant chains within the PDCPD network, has been proposed to improve these properties. However, in general, this drastically deteriorates the stiffness of PDCPD and decreases its T g . In industry, blending of two polymers with different properties is a common approach to improve the final properties of materials. [START_REF] Utracki | Commercial Polymer Blends[END_REF] Hence, the addition of non-miscible soft elastomers in a highly crosslinked epoxy has been shown to improve the ductility and toughness of the material, but it detrimentally decreases T g . [START_REF] Yee | Toughening Mechanisms in Elastomer-Modified Epoxies[END_REF][START_REF] Liu | Effect of Cross-Linking Density on the Toughening Mechanisms of Rubber-Modified Thermosets[END_REF][START_REF] Liu | Nanocavitation in Self-Assembled Amphiphilic Block Copolymer-Modified Epoxy[END_REF][START_REF] Lu | Additive Toughening Effects on New Bio-Based Thermosetting Resins from Plant Oils[END_REF][START_REF] Thomas | Morphology, Thermal, and Mechanical Properties of a DGEBA Based Epoxy Resin Toughened with a Liquid Rubber[END_REF][START_REF] Bain | Failure Processes Governing High-Rate Impact Resistance of Epoxy Resins Filled with Core-Shell Rubber Nanoparticles[END_REF][START_REF] Caldona | A Review on Rubber-Enhanced Polymeric Materials[END_REF] While addition of elastomers into PDCPD is reported to improve its flexibility and impact strength, [START_REF] Klosiewicz | US4657981A: Dicyclopentadiene Polymer Containing Elastomer[END_REF] such an "in situ effect" on PDCPD network formation and T g , directly correlated to its maximum service temperature, has to our knowledge never been reported.

The objective of the work reported herein is to highlight the role of a thermoplastic elastomer (TPE), namely Styrene-Ethylene-Butylene-Styrene (SEBS; Kraton TM G1652 commercial grade), a fully hydrogenated poly[styrene-b-(ethylene-co-butylene)-b-styrene] (Figure S1) strong and flexible TPE with excellent heat and UV resistance commonly used as impact modifier for engineering thermoplastics, [START_REF] Abreu | SBS and SEBS Block Copolymers as Impact Modifiers for Polypropylene Compounds[END_REF] as an in situ component in the rutheniumcatalyzed ROMP of DCPD (Scheme 1). Also, the influence of SEBS on the final thermomechanical properties of PDCPD, especially its T g and polymerization degree, is investigated. S1). The addition of SEBS during ROMP and eventually into the resulting PDCPD decreases the stiffness of the material, as reported for epoxy/elastomer systems. [START_REF] Yee | Toughening Mechanisms in Elastomer-Modified Epoxies[END_REF][START_REF] Liu | Effect of Cross-Linking Density on the Toughening Mechanisms of Rubber-Modified Thermosets[END_REF][START_REF] Liu | Nanocavitation in Self-Assembled Amphiphilic Block Copolymer-Modified Epoxy[END_REF][START_REF] Lu | Additive Toughening Effects on New Bio-Based Thermosetting Resins from Plant Oils[END_REF][START_REF] Thomas | Morphology, Thermal, and Mechanical Properties of a DGEBA Based Epoxy Resin Toughened with a Liquid Rubber[END_REF][START_REF] Bain | Failure Processes Governing High-Rate Impact Resistance of Epoxy Resins Filled with Core-Shell Rubber Nanoparticles[END_REF][START_REF] Caldona | A Review on Rubber-Enhanced Polymeric Materials[END_REF] In fact, the Young's modulus (E) decreases from 2.1 to 1.5 ± 0.1 GPa and maximum tensile stress ( max ) declines from 50 to 34 ± 1 MPa (Figure 1a). On the other hand, the impact strength and elongation at break ( max ) reach a maximum of 34 ± 3 kJ•m 2 and 15 ± 3 %, respectively, for  SEBS = 4wt% (Figures 1a,1b).

This trend agrees with the improved toughness and ductility of the material upon addition of an elastomer in a thermoset, in particular in terms of enhanced cavitation, shear banding or crack pinning phenomena, and reduced stiffness. However, as commonly reported, the material's stiffness is reduced at the same time. [START_REF] Yee | Toughening Mechanisms in Elastomer-Modified Epoxies[END_REF][START_REF] Liu | Effect of Cross-Linking Density on the Toughening Mechanisms of Rubber-Modified Thermosets[END_REF][START_REF] Liu | Nanocavitation in Self-Assembled Amphiphilic Block Copolymer-Modified Epoxy[END_REF][START_REF] Lu | Additive Toughening Effects on New Bio-Based Thermosetting Resins from Plant Oils[END_REF][START_REF] Thomas | Morphology, Thermal, and Mechanical Properties of a DGEBA Based Epoxy Resin Toughened with a Liquid Rubber[END_REF][START_REF] Bain | Failure Processes Governing High-Rate Impact Resistance of Epoxy Resins Filled with Core-Shell Rubber Nanoparticles[END_REF][START_REF] Caldona | A Review on Rubber-Enhanced Polymeric Materials[END_REF] For our present PDCPD/SEBS systems, whitening of samples is observed during tensile test (Figure S2b), and a rough surface is observed by SEM after impact (Figure 2c), as compared to the smooth surface observed for neat PDCPD (Figures 2a,2b). These observations suggest a cavitation mechanism and other adsorption mechanisms limiting crack propagation, due to the presence of micrometric nodules in PDCPD (Figures 2c,2d), as commonly observed for thermoset/thermoplastic blends. 31 A maximum ductility and toughness values at  SEBS = 4wt% (Figures 1a,1b) are also hinting at a larger elastomer concentration leading to particle agglomeration that decreases the yielding area density and/or favors failure defects and failure growth. [START_REF] Liu | Effect of Cross-Linking Density on the Toughening Mechanisms of Rubber-Modified Thermosets[END_REF][START_REF] Lu | Additive Toughening Effects on New Bio-Based Thermosetting Resins from Plant Oils[END_REF][START_REF] Thomas | Morphology, Thermal, and Mechanical Properties of a DGEBA Based Epoxy Resin Toughened with a Liquid Rubber[END_REF][START_REF] Bain | Failure Processes Governing High-Rate Impact Resistance of Epoxy Resins Filled with Core-Shell Rubber Nanoparticles[END_REF][START_REF] Caldona | A Review on Rubber-Enhanced Polymeric Materials[END_REF] Rewardingly, in the present PDCPD/SEBS materials, these classical variations of mechanical properties are coupled with an unexpected improvement of the thermal properties. Indeed, the glass transition is observed over a narrower temperature range (Figure S3) and reaches a maximum value of T g = ca. 165 ± 1 °C (Figure 1c) at  SEBS = 4wt% (as compared to T g ~ 158 ± 1 °C for neat PDCPD). Moreover, the rubbery plateau, E ' r , as determined by DMA, increases from ca. 10 to 19 ± 1 MPa, corresponding to a molar mass between crosslinks, M c , varying from 1 200 to 600 g•mol 1 . These observations are in contrast with those previously reported for other highly crosslinked thermosets such as epoxy materials where the addition of a soft elastomer or plasticizer tends to decrease the T g . [START_REF] Yee | Toughening Mechanisms in Elastomer-Modified Epoxies[END_REF][START_REF] Liu | Nanocavitation in Self-Assembled Amphiphilic Block Copolymer-Modified Epoxy[END_REF][START_REF] Lu | Additive Toughening Effects on New Bio-Based Thermosetting Resins from Plant Oils[END_REF][START_REF] Thomas | Morphology, Thermal, and Mechanical Properties of a DGEBA Based Epoxy Resin Toughened with a Liquid Rubber[END_REF][START_REF] Bain | Failure Processes Governing High-Rate Impact Resistance of Epoxy Resins Filled with Core-Shell Rubber Nanoparticles[END_REF] In addition, the polymerization degree of DCPD, , as measured by DSC (Figure S4), increases from 75 ± 5 % for neat PDCPD to 87 ± 5 % for PDCPD/SEBS with  SEBS = 4wt% (Figure 1d). In summary, the best compromise between mechanical and thermal properties is obtained for  SEBS = 4wt% in PDCPD (Figure 1).

0 2 4 6 8 1,5 1,6 1,7 1,8 1,9 2,0 2,1
 SEBS [wt%] 35 40 45 50 In order to elucidate this unexpected yet valuable effect of SEBS on the thermal properties of PDCPD, in situ temperature measurements (Figure 3), isothermal DSC (for 5 min at various temperatures) and further complementary anisothermal analyses (following isotherms; from 40 to 300 °C at 30 °C•min -1 ) were performed, and the polymerization kinetics at each isothermal temperature (Figure 4) was studied for both neat DCPD and DCPD/4wt% SEBS.

E [GPa]  max [MPa]  max [%]  max  max E a)
As shown in Figure 3, similar maximum in situ temperatures T max = ca. 180 °C and 130 °C were recorded for both DCPD and DCPD/4wt% SEBS systems, respectively, in the core or at the mold wall of the plate. This is due to the very exothermic polymerization reaction associated with the energy released by cyclic olefin ring opening. [START_REF] Ivin | Olefin Metathesis and Metathesis Polymerization[END_REF] A slight reaction delay (ca. 5 s) was observed at  SEBS = 4wt%, probably due to the resin viscosity (, measured using a Brookfield viscosimeter) increasing from 6 to 96 cP and/or to the DCPD dilution effect. High in situ temperatures (> 100 °C) were measured in the mold for few tens of seconds (Figure 3). T iso ) (Figure 4). This is within the same order of magnitude as the time measured during molding, at high temperature (Figure 3). We thus suggest that macromolecules of SEBS, thanks to their solubility in DCPD, act as a lubricant or plasticizer. This phenomenon induces the mobility of the polymer material during polymerization, thus enabling in turn a higher DCPD polymerization rate. This would account for improving polymerization degree of DCPD at short molding time, thus increasing the crosslinking density and the glass transition temperature of PDCPD in the presence of SEBS. In summary, we have demonstrated that the addition of a small amount (4wt%) of SEBS TPE significantly increases both the toughness and T g of PDCPD (in direct correlation to its maximum application temperature) without dramatically affecting its stiffness. These thermomechanical properties improvements are suggested to arise from the plasticizing effect of SEBS during molding, leading to better polymerization degree and crosslinking density of PDCPD, as supported by DSC and DMA analyses. This unexpected result paves the way to the tuning of PDCPD properties upon adjusting the elastomer chemical structure and morphology. Further studies changing the elastomer nature are currently in progress for maximizing toughening effect and T g value.

Supporting Information

Experimental section. ). 1 No signals arising from potential residual double bonds derived from the butylene monomer ( H between 5 and 6 ppm) 2 within the main backbone of SEBS were detected by 1 H NMR spectroscopy (Figure S1) thus supporting its fully hydrogenated characteristics. First generation ruthenium catalyst (M101 ® Umicore (CAS number: 250220-36-1); Sigma-Aldrich, Saint-Louis, USA), dissolved (2wt%) in toluene (HPLC grade), was used for the DCPD ROMP. This catalyst was selected for its lower activity as compared to a second generation ruthenium catalyst, thereby avoiding a rapid gelation and enabling a more homogenous mixing before casting. S1. Classically, the stiffness of the sample decreases, characterized by a drop of both the Young's modulus E and the maximum tensile stress  max , from 2.1 to 1.5 ± 1 GPa and from 50 to 34 ± 1 MPa, for neat PDCPD to PDCPD/8wt% SEBS, respectively. In parallel, the strain at break,  max , in tensile test slightly increases to 15 ± 3% (from 13 ± 3% for neat PDCPD) (Figure S2 More significantly, the Izod impact strength reaches 34 ± 3 kJ•m 2 (from 13 ± 3 kJ•m 2 ), with 4 wt% of SEBS (Table S1). Both a maximum ductility and toughness value are noted for this SEBS concentration. Figure S3 shows the variation of the storage modulus, E', and the damping factor, tan  as a function of temperature for neat PDCPD and PDCPD/SEBS samples, as measured by DMA.

The addition of SEBS increases the glass transition temperature (T g ) of PDCPD, the elastic rubbery modulus plateau (E' r ), and narrows the range of the glass transition temperature.

Maximum values were measured for  SEBS = 4wt%, where T g and E' r reached 165 ± 1 °C and 19 ± 1 MPa, as compared to 158 ± 1 °C and 10 ± 1 MPa for neat PDCPD, respectively. E'

[MPa] 0,0

f =1 Hz S5e -k), the polymerization rate appears to be delayed at the onset of the reaction in the presence of 4wt% of SEBS; this is likely due to the resin viscosity (as measured using a Brookfield viscosimeter) that increases from  = 6 to 96 cP and/or a DCPD dilution effect.

T g ~ 158°C T g ~ 165°C tan  E' tan  E' r ~ 10 MPa
However, systematically, the polymerization time required to reach 95% of the maximum normalized polymerization degree, t 0.95 , is in the order of a few tens of seconds shorter, especially above T iso > 100 °C where the SEBS phase is completely plasticized. We suggest that the soft SEBS macromolecule plays the role of a lubricant or plasticizer during ROMP, thereby improving the polymerization rate of DCPD during the short molding time (few tens of seconds (Figure 3)), especially at high temperatures.

Scheme 1 .

 1 Scheme 1. ROMP of DCPD

Figure 1 .Figure 2 .

 12 Figure 1. Main tensile (a), impact (b), thermomechanical (c) and calorimetric (d) characteristics of neat PDCPD and PDCPD/SEBS as a function of SEBS content,  SEBS

Figure 3 .

 3 Figure 3. In situ temperature monitoring over time during molding of neat DCPD and DCPD/4wt% SEBS

Figure 4 .

 4 Figure 4. Polymerization degree,  (a) and time variations to reach 95% of the maximum polymerization degree at each isothermal temperature, t 0.95 , (b) as a function of isothermal temperature, T iso .

Figure S1. 1 H

 1 Figure S1. 1 H NMR (300 MHz, CDCl 3 , 25 °C) full (bottom) and zoomed (top) spectra of SEBS (Kraton TM G1652); * stands for residual solvent signal.

Figure

  Figure S2 presents the average tensile curves for neat PDCPD and PDCPD/SEBS

  .a). This is correlated to an elongation mechanism change with the addition of SEBS, favoring cavitation as suggested by specimen whitening (Figure S2.b).

Figure S2 .

 S2 Figure S2. Average tensile curves for neat PDCPD and PDCPD/SEBS samples (a) and photos of tensile specimens of neat PDCPD and PDCPD/4wt% SEBS during tensile test (b)

Figure S3 .Figure S4 .

 S3S4 Figure S3. DMA analysis of neat PDCPD and PDCPD/SEBS samples

1 T 1 H 1 TFigure S5 .

 111S5 Figure S5. Quasi-isothermal (a, c) and associated anisothermal (b, d) DSC thermograms for neat DCPD (a, b) and DCPD/4wt% SEBS (c, d) samples. Normalized polymerization degrees, (t), at various isothermal temperatures T iso during isotherms (ek)

  1 H NMR spectrum of SEBS commercial grade used. Raw thermo-mechanical data of PDCPD/SEBS samples (tensile tests, Izod impact, DMA & DSC analysis).

	Experimental section
	Materials and methods.
	Liquid DCPD/TCPD mixture (85/15 w/w as determined by 1 H NMR) was prepared by
	heating solid DCPD (99% purity; Maruzen Petrochemical Co., Ltd., Ichihara, Japan) at 200°C
	for 4 h under argon at atmospheric pressure. This monomer mixture is referred to DCPD.
	Styrene-Ethylene-Butylene-Styrene,	a	poly[styrene-b-(ethylene-co-butylene)-b-
	styrene] (SEBS; 30wt% styrene content; Kraton TM G1652) TPE (physically crosslinked), was
	supplied by Kraton Corporation (Houston, USA; T g = 36 °C and 96°C, average number
	molar mass (M

n ) ca. 54 000 g.mol 1

Table S1 .

 S1 Main mechanical properties of neat PDCPD and PDCPD/SEBS samples

			Tensile test		Izod Impact
	SEBS concentration [wt%]	Young's Modulus E [GPa]	Max stress [MPa]  max	Strain at break [%]  max	Impact strength [kJ.m -2 ]
	0	2.1 ± 0.1	50 ± 1	13 ± 3	13 ± 3
	2	1.8 ± 0.1	45 ± 1	13 ± 4	32 ± 2
	4	1.8 ± 0.1	42 ± 1	15 ± 3	34 ± 3
	8	1.5 ± 0.1	34 ± 1	14 ± 5	11 ± 3

Acknowledgements

S10

The authors thank the French Foundation of La Maison de la Chimie for its financial support. We are grateful to Mr. Francis Gouttefangeas (UAR 2025 ScanMAT, Rennes, France) for SEM images.