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Background Laparoscopic subtotal cholecystectomy (LSC) is a recognised option when the “critical view” cannot be safely delineated. It carries a high morbidity rate with increased frequencies of a bile leak occurring however reducing the risk of bile duct injury. LSC can be classified into fenestrating or reconstituting cholecystectomy and surgical practice varies as reconstituting is considered to be more complex. Our aim of the study was to look at LSC with respect to the techniques used, complications and the overall outcomes. Methods All adult patients undergoing LSC between January 2015 – December 2021 were retrospectively identified on our electronic database. Data gathered included: Patient demographics, previous acute biliary presentations, operative details/technique, length of stay (LOS), 30-complications, 30-day mortality, readmissions and follow up investigations/procedures. Descriptive statistics, Chi squared, and relative risk were used to analyse results. Results 170 patients underwent LSC in the study period with the rate increasing most years. Median age was 67 with 86:84 Female to Male ratio. Rates varied drastically between different surgeons from 0.1% to 19% compared to total number of laparoscopic cholecystectomies. 130 (76%) were performed in the acute setting and 63/170 (37%) had previous acute biliary presentations. Median LOS was 5 days. Most patients had Fenistrating LSC (155 [67.6%] vs. 55 [32.3%]). 80 (47%) patients had complications. These were graded by Clavin-dindo grade: I – 3 (3.7%); II – 34 (42.5%); IIIa – 26 (32.5%); IIIb – 16 (20%) and IV – 1 (1.25%). The most frequent complication was bile leak; 60 (35.2%) followed by collection 8 (4.7%). Other notable complications were pancreatitis; 3 (1.7%), AKI; 2 (1%), bile duct injury; 1 (0.5%) and duodenal injury; 1 (0.5%). 16 (9.4%) patients had returns to theatre, 14 (8.2%) patients had readmissions and 35 (20.5%) had multiple attendances to the day unit following discharge. Further analysis demonstrated that that fenestrated technique was associated with a greater risk of bile leak (p Conclusions We present one of the largest single unit datasets on LSC, and the 2nd largest from UK population. Our rate of LSC is increasing, likely as a safe alternative to open conversion, with large surgeon variability. The majority are performed in the acute setting with the fenestrated technique. We have demonstrated however that LSC has a high morbidity, both in reoperation/reintervention rate, readmission and complications accompanied by high follow-up requirement. Despite fenestrated being the favoured technique in our unit we have shown that it has poorer outcomes. Our data would suggest that if LSC is to be performed then the reconstituted technique should be used if possible.

Background Bariatric and metabolic surgery (BMS) has a low complication and readmission rate; complications however, when they do occur, can be major and life-threatening. Routine post-operative blood testing (POBT) is commonplace following BMS to assess for complications but has resource implications. We aimed to assess whether POBT in our unit predicted complication or readmission rates. We found no existing studies evaluating the efficacy of routine POBT in the bariatric surgery cohort. Methods All patients undergoing BMS between July ’20 – June ’21 were retrospectively identified from our local database. Data gathered were: Patient demographics; operation, POBT (FBC, U&E, CRP); length of stay; 30-day complications and 30-day readmissions. Financial cost of POBT were also calculated. Descriptive statistics and Fishers exact test were used to analyse results. Results 149 patients were identified (OAGB - 81, RYGB - 32, LSG - 36); all had POBT. 115 patients (77%) were discharged on the expected post-operative day (median LOS - 1 days). 38 patients (25.5%) had abnormal POBT results according to defined parameters laid out in our protocol. Abnormal POBT resulted in a change to management plan in 8 patients (5.4%), with subsequent increased LOS for further investigation or observation; in all of these cases there were signs of deterioration via observations and/or clinical symptoms. 8 (5.4%) patients were readmitted in 30-days, 3 of whom had abnormal POBT following their surgery. There was no statistical correlation between abnormal POBT and 30-day readmission rate, p=0.42. POBT in the cohort total cost was in the region of £2400. Conclusions In this study we observed that POBT did not predict adverse outcome without clinical signs of deterioration. A considerable number of POBT are performed routinely without clinical indication. A patient-specific approach is recommended based on intra-operative and post-operative clinical assessment rather than routine usage, resulting in cost savings to the Trust and better patient flow with safe and efficient discharges. It is also important to consider the financial impact of performing routine POBT in all patients undergoing BMS; due to both the costs of POBT, staff hours as well as the potential costs due to delayed discharges.

Background The availability and popularity of bariatric and metabolic surgery (BMS) continues to increase worldwide and in turn so do the resources allocated to it. The last NBSR report (2020) demonstrated that 70% of patients were discharged on the second postoperative day and 80% left after the third day. An amended protocol was implemented within our Trust switching from a 2–3 night stay and reducing this to a planned one-night stay for a more efficient service. This review evaluates the safety and efficacy of a one-night stay protocol. Methods All patients undergoing BMS between two sets of dates were retrospectively identified from our local database, pre and post protocol change. Group A (old protocol, July-December ’19) and Group B (one-night stay protocol, July ’20-July ’21). Group B capture time was extended due to smaller numbers due to COVID. Data gathered included: Patient demographics (Age, Gender, ASA, Weight, BMI); operation; length of stay (LOS); 30-day complications, 30-day mortality, and 30-day readmission rates. Descriptive statistics and Chi-squared test were used to analyse results. Results Group A had 94 patient and Group B 149 patients. Patient demographics, weight and ASA were similar in both groups. There were significantly more RYGB in Group A whilst more OAGBs and sleeves in Group B: RYGB; (48[51%] vs. 30[20%]), OAGB; (32[34%] vs. 80[53%]), Sleeve; (13[14%] vs. 36[24%]). Median LOS reduced from 3 days to 1 day and mean LOS 3.2 days to 1.3 days. In Group B, 115 patients (77%) were discharged on post-operative day 1 vs. 18 (19%) in Group A. In the 34 (23%) of patients that required stay beyond day 1 in Group B the most common reason was post-operative nausea and vomiting (n=8). Other frequent reasons were pain (n=5), low urine output/AKI (n=5) and not tolerating oral diet (n=4). There were no statistically significant differences between groups for 30-day complication (6[6%] vs. 5[3%] p=0.4) or re-admission (4[4%] vs. 8[5%] p=0.9) rates. In sub-group analysis, there was no difference between operation type and LOS/complication rates. In a review of the readmissions, it was not felt any were avoidable and only 1/8 readmissions were within 48h of discharge - this patient already had an extended admission. Conclusions This study demonstrated that a planned one-night stay following BMS is both safe and effective; facilitating early patient discharges whilst having the necessary safety netting steps for those who require a require an extended period in hospital. The next step would be to explore the safety of day case surgery for selected patients undergoing sleeve gastrectomy.

ConspectusAlmost all aspects of daily life involve polymers in some form or the other. However, polymer production is largely based on finite feedstocks. These limitations combined with environmental concerns force us to rethink the strategies for the synthesis of these materials. As an abundant and renewable resource, biomass is composed of a very diverse range of molecules that deserve to be valorized. The development of new methods for transforming biomass into resources suitable for polymer production remains a crucial hurdle on the road to a more sustainable chemical economy. The main challenge is to design efficient and selective transformations of abundant and inexpensive raw materials into innovative polymers. For the chemical industry to meet these challenges, process intensification must play an important role in developing cleaner and more energy-efficient technologies while aiming for safer and more sustainable processes. Catalysis is an important tool to support more sustainable plastics production by being ideally efficient, practical, and versatile. In this regard, the creation of sustainable polymers through one-pot catalysis represents an exciting frontier in materials science.In this Account, we describe some of the published advances for achieving one-pot synthesis of biobased monomers and the resulting (co)polymers. These studies demonstrate that one-pot reactions can produce sustainable materials for a wide range of applications. We show that these new multistep "one-pot" approaches are very promising from an academic and industrial point of view. These synthetic schemes have indeed allowed us to investigate the formation of new polyesters, polypeptides, and poly(meth)acrylates by different polymerization mechanisms. We discuss their efficiency by highlighting their ability to perform multiple (quantitative) synthetic transformations and bond formation steps while bypassing multiple purification procedures at the same time. While enabling the development of novel polymeric structures, we demonstrate that these one-pot procedures can also contribute to reducing the environmental footprint.In light of the growing concerns for sustainable development, these procedures may therefore allow, in the near future, one to prepare sustainable polymeric materials with advanced properties through extremely simplified routes from renewable feedstocks. Among these materials, block and alternating copolymers are unique structures that can exhibit a wide range of properties. While their multistep synthesis remains a demanding process, the one-pot synthesis of these polymers is much more scalable and can create multiblock or alternating copolymers with a wide range of potential sequences. These approaches then give access to materials whose structure and functionality can be designed to suit the need.

To solve some of the environmental problems associated with oil extraction and make plastics production sustainable, there is increasing interest in developing selective methods to convert renewable feedstocks into monomers suitable for polymer production. Here we present a catalytic one-pot synthesis of polycarbonates from renewable resources. This approach relies on the use of a commercially available magnesium catalyst that allows the coupling of diethyl carbonate with a rigid camphor-based diol. In combination with a solvent-free polymerization, this sequence can also be extended to different diols , providing direct access to a new library of unique polycarbonates. Additionally, chemical recycling of these polycarbonates could be triggered by magnesium-catalyzed methanolysis.

This thesis aims to analyse the effect of a cutting tool assisted (VAM) with 40-kHz vibration on C45 steel samples. It exposes the improvement of surface finish through vibration application and the different effects thus generated while machining process. The vibratory movement of the cutting tool is one-dimensional, and cutting tests are performed on a lathe machine. The study is mainly divided into two stages: the analyses of the effect of vibration assistance, feed and tool angle on the cutting force and roughness by means of a design of experiment. Then, the observation and characterisation of the chips removal mechanism with a high-speed camera to characterize the influence of the vibratory effect on its formation. The state of art section provide knowledge to understand the subject by exposing all the research and studies similar from our topic to justify the experiments that will be carried out. All procedures to achieve the research objectives are described, including the experimental design, experimental setup and the materials used to conduct them. It is concluded that one dimensional vibration assisted machining (VAM) offers distinct advantages over conventional machining (NVAM). The surface quality is improved when the cutting parameters are carefully implemented; adding vibration is the most significant effect on the surface quality providing lower Ra values than NVAM. VAM has demonstrated that applying vibration as a significative influence on the chip removal mechanism. Indeed, the chip fragmentation is facilitated by the VAM process by forming arc loose chips which ultimately improve the surface quality and tool wear resistance by limiting the friction due to enhanced evacuation of the chip. The texturization effects of VAM to obtain specific surface texture are also observed. From VAM to NVAM, two different patterns are easily detected (linear and mesh shape), the level intensity depends mainly on the feed rate.

We demonstrate that the strong N2 bond can be efficiently dissociated at low pressure and ambient temperature on a Si(111)-7x7 surface. The reaction was experimentally investigated by scanning tunnelling microscopy and X-ray photoemission spectroscopy. Experimental and density functional theory results suggest that relatively low thermal energy collision of N2 with the surface can facilitate electron transfer from the Si(111)-7x7 surface to the p*-antibonding orbitals of N2 that significantly weaken the N2 bond. This facile N2 triple bond dissociation on the surface leads to the formation of a Si3N interface.

Background In the UK around 50% of cases of pancreatitis are caused by gallstones. BSG guidelines recommend ERCP is undertaken within 72h of onset of pain and patients should undergo definitive treatment with cholecystectomy if fit enough during the index admission or within two weeks of discharge to avoid the risk of potentially fatal recurrent pancreatitis. A national audit in 2015 showed that 34.2% of patients receive definitive treatment. During the first COVID-19 wave our surgical service was forced to modify practice including more conservative/non operative management potentially increasing the possibility of recurrent pancreatitis and thus complications. Methods We performed a retrospective audit of patients presenting to our unit with gallstone pancreatitis during the first wave of the COVID-19 pandemic from March to August 2020 (COVID) and compared this to the same period in 2019 (pre-COVID). Patients were filtered from a larger dataset of all admissions with an ICD-10 coding of any biliary disease. Patient demographics, admission details, investigations, surgical management and post-operative complications were recorded. This was then audited against the standards in the BSG guidelines for the management of pancreatitis. Results Conclusions There were significant differences in the management of the groups. Most significantly in the number of hot procedures and number of patients receiving definitive treatment, a consequence of the conservative approach during COVID. Our pre-COVID results are similar to our previous audit in 2016; 76% received definitive treatment. Those that didn’t have definitive treatment were generally due to frailty/co-morbidities. Majority of ERCP delays were due to weekend effect. Of the 40 patients who didn’t receive definitive treatment 16 have represented with biliary flares/pancreatitis in the year following the study period highlighting the importance of definitive treatment.

Background Laparoscopic subtotal cholecystectomy (LSC) is a recognised option when the “critical view” cannot be safely delineated. It carries a high morbidity rate as there are increased frequencies of a bile leak occurring however reducing the risk of bile duct injury. LSC can be further divided into fenestrating or reconstituting cholecystectomy, the later entails closing the remnant. The literature state reconstituting cholecystectomy reduced rate of bile leak. We reviewed our cases to analyse the complication rates of LSC and there outcomes. Methods A retrospective review of patients who underwent a laparoscopic subtotal cholecystectomy (LSC) using electronic records between January 2015 to March 2021. A total of 160 patients, with a mean age of 65, 51% male and 49% female. Results 76% of LSC were performed as an emergency. Mean operation length was 96min and the mean blood loss 92ml. Complications occurred in 50% of patients. Post operatively 22% underwent an ERCP and the re-operation rate was 9%. The mean length of stay was 8 days. Conclusions Based on our results LSC carry a high rate of bile leak with the majority requiring intervention in the form of ERCP or laparoscopy and wash out. A reconstituting cholecystectomy, closing with an endoloop of suture seems to slightly reduce the rate of bile leak. LSC are only performed when managing a difficult gallbladder with a dense/ inflamed Calot's triangle. There were no mortalities associated with a LSC.

Background Biliary disorders make up a significant proportion of the acute general surgical workload. Effective management allows definitive treatment with relief of symptoms and reduced impact to patients due to recurrent admissions and complications. During the first COVID-19 wave and lockdown there were reduced surgical presentations to hospital and patients presented later. Surgical services were forced to implement different practices including more conservative/non operative management potentially increasing the possibility of recurrent presentations and greater complications in biliary-pancreatic presentations. Methods We performed a retrospective audit of patients presenting to our unit with ICD 10 codes: K80;Cholelithiasis, K81;Cholecystitis and K85;Acute pancreatitis. We used the period of the first wave of the COVID pandemic March – August 2020(COVID) and compared this to the same period in 2019(pre-COVID). On note review those with inaccurate coding were excluded. Patient demographics, admission details, investigations, surgical management, operative details, and post-operative complications were recorded. The primary outcomes were change in operative management, representation, and post-operative complications. χ2 test was used to test for significance of categorical variables. Results Conclusions The two groups were demographically similar with equal spread of primary diagnoses however there were significant differences in outcomes. Patients presenting with cholecystitis and gallstone pancreatitis had significantly reduced rates of definitive management. The increase in adverse operative findings is likely secondary to patients presenting later and initial conservative management. The increase in complications for the COVID cohort correlates with the increase in adverse findings/operative complexity. Conservative management with the aim of reducing COVID exposure inadvertently resulted in increased risk to patients with increased presentations/admissions. Despite this risk there were no COVID cases in our cohort.

IntroductionIncisional hernia has an incidence of up to 20% following laparotomy and is associated with significant morbidity and impairment of quality of life. A variety of surgical strategies including techniques and mesh types are available to manage patients with incisional hernia. Previous works have reported significant heterogeneity in outcome reporting for abdominal wall herniae, including ventral and inguinal hernia. This is coupled with under-reporting of important clinical and patient-reported outcomes. The lack of standardisation in outcome reporting contributes to reporting bias, hinders evidence synthesis and adequate data comparison between studies. This project aims to develop a core outcome set (COS) of clinically important, patient-oriented outcomes to be used to guide reporting of future research in incisional hernia.MethodsThis project has been designed as an international, multicentre, mixed-methods project. Phase I will be a systematic review of current literature to examine the current clinical and patient-reported outcomes for incisional hernia and abdominal wall reconstruction. Phase II will identify the outcomes of importance to all key stakeholders through in depth qualitative interviews. Phase III will achieve consensus on outcomes of most importance and for inclusion into a COS through a Delphi process. Phase IV will achieve consensus on the outcomes that should be included in a final COS.Ethics and disseminationThe adoption of this COS into clinical and academic practice will be endorsed by the American, British and European Hernia Societies. Its utilisation in future clinical research will enable appropriate data synthesis and comparison and will enable better clinical interpretation and application of the current evidence base. This study has been registered with the Core Outcome Measures in Effectiveness Trials initiative.PROSPERO registration numberCRD42018090084.

The most versatile furanic building block for chemical and polymer applications is 2,5-furandicarboxylic acid. However, the classical 2,5-furandicarboxylic acid production methodology has been found to have significant drawbacks that hinder industrial-scale production. This review highlights new alternative methods to synthesize 2,5-furandicarboxylic acid that are both more advantageous and attractive than conventional oxidation of 5-hydroxymethylfurfural. This review also focuses on the use of 2,5-furandicarboxylic acid as a polymer precursor and the various potential applications that arise from these furan-based materials.

Inflatable structures are part of the family of tensioned textile membrane structures. The operating principle is common for all these type of structures: the stiffness of the structure relies on t...

International audience; A composite structure with an highly flexible polymer substrate and a thin film of lead zirconate titanate, Pb(Zr,Ti)O3 (PZT), is realized using an all‐chemical process. The fabrication of the structure comprises three steps: first, PZT is deposited on an aluminum thin foil, then the PZT thin film is bonded to a polymer, and, finally, aluminum foil is removed by selective chemical etching. Structural characterization techniques are used to ensure the quality of the PZT/polymer composite structure. Electrical measurements are also performed to confirm the ferroelectric characteristics of the composite. Finally, energy harvesting measurements are realized with interdigitated electrodes structure. A maximal energy density of 20 μJ cm−2 is obtained with manual mechanical excitation and an output voltage up to 35 V under free oscillations conditions in bending mode. This demonstrates that the recently developed PZT/polymer thin films are very promising for low‐frequency vibrating energy‐harvesting applications.

International audience; Dans le cadre des projets N-air-J, MIGAC et Airbivore, financés respectivement par la région Pays de la Loire, le RFI WISE et le CNRS, des films piézoélectriques flexibles de zircono-titanate de plomb (PZT) ont été développés sur substrat flexibles au sein de l’Institut d’Électronique et de Télécommunications de Rennes (IETR). L’objectif principal de ces projets est d’étudier la possibilité de récupérer l’énergie mécanique de courants d’air grâce à l’utilisation de micro-générateurs piézoélectriques flexibles. Les couches minces de PZT, lorsque elles sont électriquement polarisées, possèdent en effet des propriétés piézoélectriques macroscopiques leur permettant de convertir l’énergie mécanique en énergie électrique, et inversement. De par le budget thermique élevé nécessaire à la cristallisation du PZT (autour de 650 °C), ces couches minces sont généralement déposées sur des substrats rigides de silicium, de saphir ou encore de MgO.Dans cette présentation est décrit le procédé de fabrication par Chemical Solution Deposition (CSD) de films de PZT flexibles déposés sur feuille d’aluminium en structure Métal-Isolant-Métal (MIM)1, ainsi que les caractérisations ferroélectriques et piézoélectriques des condensateurs obtenus. De par leur faible épaisseur (20 µm) et la conformabilité de l’aluminium, les films réalisés sont facilement découpables et permettent d’obtenir des géométries originales.Ces films, étant réalisés pour des applications de récupération d’énergie, ont été caractérisés sur un banc mécanique à des fréquences d’excitations forcées très basses (dans la gamme de l’Hertz). Du fait de la forte permittivité du PZT et de sa faible épaisseur, le générateur piézoélectrique présente une forte capacité (autour de 200 nF), ce qui limite la tension de sortie du générateur à quelques centaines de millivolts. Afin d’augmenter cette tension de sortie, et par conséquent la puissance du générateur, le film de PZT est transféré par voie chimique sur un film polymère de polytéréphtalate d’éthylène (PET). La suppression du plan de masse, allié à une structure d’électrodes interdigitées (IDE) permet d’obtenir des tensions de sortie supérieures à 30V.

International audience; La présente édition de la Lucarne matérialise la poursuite d’un travail engagé depuis 2013. Comme pour la précédente livraison, il a été réalisé dans le cadre d’un atelier collaboratif d’histoire socioculturelle. L’atelier lui-même est animé par un collectif formé des enseignant∙e∙s et auditeur∙rice∙s des formations du CNAM dédiées à la médiation socioculturelle des sciences et techniques. Certificat de compétences, Licence professionnelle ou Magister s’attèlent ainsi à la réflexion, à la conception et à la réalisation de dispositifs pour la médiation des sciences et techniques en société par le design culturel. C’est dans ce cadre de réalisation pédagogique que sont rassemblés ces textes et documents pour lesquels sont proposés de courtes analyses sur leur fonction de support de diffusion massive dans l’espace public d’une culture populaire et ordinaire des sciences et techniques. Tous ont été rédigés dans le cadre d’un exercice exigé pour la validation d’un enseignement. Si le résultat final peut s’avérer inégalement satisfaisant à l’aune des critères de leurs commanditaires, tous les textes apportent cependant un regard jugé pertinent sur un des aspects des manifestations des sciences et techniques dans leurs rapports à la société au travers de la production et de la consommation culturelle de masse. Quelques-uns ont été un peu remaniés pour la présente édition. Retrouvez-les tous, ainsi que d’autres non publiés dans ce volume, sur le site de la Lucarne : http://ateliercst.hypotheses.org/Avec les contributions de Philippe Cholet, Christophe Thomas, Julie Piskor, Prisca Cez, Karine Guillon, Jessica Signahode, Antonella Cavanna, Claire Robin, Daphné Debilly, Claire Combettes, Fabienne Thomas, Annie Dumont, Alexandre Couturas, Mirielle Rineau, Jan-Philippe Dubroca, Cyndie Dupoux, Laurent Marche, Carole Zagouri, Mario Vocale, Julie Daviet-Draye, Marie Berlingue, Gisele Butterlin, Laurène Legrand, Ludivine Cavé, Frederic Pitout, Delphine Blanchard, Charlotte Joguet, Alexandre Ben Othman, Roxane Bibard, Victoire Chabert, Morgane Petit, Ariane Rudelle, Tanit Halfon, Marie Danielle et Meryem Hameg.

In this work, we consider inflatable beams and define their limit states, in terms of displacements, wrinkling, and collapse of the beam. The definition and properties of the collapse load are highlighted. Concerning the displacements, the strength of material dedicated to inflatable tubes has been studied by different authors, and is considered as well-known now in the linear part of the behavior (before the wrinkle appears). The need concerns now the behavior of the beam in the non-linear part of its behavior. An analytical formulation that allows to get the displacement in this non-linear part, i.e. between the winkling load and the collapse load has recently been written. This approach is here extended to the use of a beam finite element with which the displacements can be obtained from light loads to the collapse load of more complex structures. The case of an inflatable arch is presented as an example.

Over the past decade, on-surface fabrication of organic nanostructures has been widely investigated for the development of molecular electronic devices, nanomachines, and new materials. Here, we introduce a new strategy to obtain alkyl oligomers in a controlled manner using on-surface radical oligomerisations that are triggered by the electrons/holes between the sample surface and the tip of a scanning tunnelling microscope. The resulting radical-mediated mechanism is substantiated by a detailed theoretical study. This electron transfer event only occurs when Vs < -3 V or Vs > + 3 V and allows access to reactive radical species under exceptionally mild conditions. This transfer can effectively ‘switch on’ a sequence leading to formation of oligomers of defined size distribution due to the on-surface confinement of reactive species. Our approach enables new ways to initiate and control radical oligomerisations with tunnelling electrons, leading to molecularly precise nanofabrication.

International audience; Highly flexible lead zirconate titanate, Pb(Zr,Ti)O3 (PZT), thin films have been realized by an all chemical process on a plastic substrate. The procedure is composed of three steps: the first one is the PZT deposition on aluminium thin substrate, the second step corresponds to the bonding PZT thin film to a polymer layer and the final step is the aluminium substrate etching. Diffractions and microscopy techniques were used to check the quality of the new PZT/polymer composite structure. Polarization hysteresis and permittivity measurements were also performed to determine the electrical characteristics of the composite. These results demonstrate that the recently developed PZT/polymer thin films are very attractive for both bending actuation and sensing as well as for low frequency vibrating energy harvesting applications.

Tensioned textile membrane structures are now common in the field of construction and they are the subject of a standardization process to harmonize the design rules among Europe. The stiffness of the structure relies on the pretension of the membrane, which can be provided mechanically or pneumatically. The stiffness of pneumatic structures depends on the internal pressure. They are able to support external loads which are much more important than their own weight. A first reliability study is conducted on a two parallel inflatable beams structure, which can be used as a footbridge. The serviceability limit states (SLS) and ultimate limit state (ULS) are defined. The reliability analysis is conducted with the FORM method, providing reliability indices as well as sensitivity factors.

International audience; An inflatable beam is an airtight structure made of a soft technical fabric and subjected to an internal pressure which gives it a final cylindrical shape, a pre-stress in the membrane and a bearing capacity. Against all appearances, it is not a standard beam and it requires a specific formulation in order to take account of the internal pressure which plays a key role in its mechanical response. This work deals with inflatable beams made of orthotropic materials. The first part of the paper is concerned with the inflation of the membrane tube, an important stage which is often neglected so far in the literature. As preliminaries of the bending problem studied in the next part of the paper, the constitutive law related to the inflated state of the tube – not the natural state – is investigated. It will be shown that the consti-tutive law related to the inflated pre-stressed state is not the same as the constitutive law related to the natural state. Expressions of the material coefficients involved in the former constitutive law will be established from the material coefficients defined on the natural reference configuration which are the only ones supposed to be known. The second part of the paper deals with the bending of the inflatable beam. The Tim-oshenko beam kinematics will be chosen because of the significant shear effect in the tube wall and the problem will be formulated in finite deformations in order to accounts for all the nonlinear effects, in particular the action due to the internal pressure which is a follower load. The nonlinear system of equations obtained will then be linearized around the pre-stressed configuration and will result in a more tractable linear system. The proposed formulation allows a comprehensive study of the influence of the internal pressure on the geometry and material properties of orthotropic inflatable beams The analytical results will be compared with numerical results obtained from a nonlinear membrane finite element code.

International audience; Wind tunnels are usually designed for a prerequisite purpose. Wind tunnels for aeronautical studies aim at reproducing very low turbulence flow at high speed, what they attain through a settling chamber and funnelling effect with a contraction ratio of the section by 8 to more, BLWT are designed for making a boundary layer grow, what means a long flat floor upstream the model and industrial wind tunnel are designed with a continuous flat floor allowing forklifts and other handling vehicles to travel inside. It is therefore difficult to change the initial destination of a wind tunnel, pulling down walls and rebuilding is costly. In order to overcome this issue, an innovative device has been developed for the Jules Verne large climatic wind tunnel, with the aim to modulate its section, opening it to new markets. This device allows a fast and cheap adaptation of the size and shape of the wind tunnel section. Experience of the wind tunnel team with inflatable structures, initially related to modelling of mechanical behaviour of standalone structures under wind loads , was used for taking the challenge of the design, dimensioning and validation of new devices, to be used for changing the shape of the existing wind tunnel.

International audience; Flexible piezoelectric device has been realized by depositing lead zirconate titanate (PZT) thin films by Chemical Solution Deposition (CSD) onto very thin aluminium foil (16 µm) and using polyethylene terephthalate (PET) laminated film (150 µm) as encapsulation. A ruthenium dioxide layer has been used in order to enhance the quality of the PZT/Al interface, improving the dielectric, ferroelectric and piezoelectric properties of the PZT film. The obtained piezoelectric generators have been subjected to large bending motions at low frequencies ranging from 0.1 to 8 Hz and the experimental values of the output voltage, output current and harvested power have been compared to theoretical values (derived from the electrokinetic model of the piezoelectric material) with a very good agreement. Due to the increase of the permittivity of the PZT film by the use of RuO2 interlayer, moderate decrease of the harvested power at the optimal load resistance is found (from 185 nW to 143 nW at 4.4 Hz), despite the enhancement of the piezoelectric properties. This type of very flexible film able to withstand small radius of curvature (1 cm) may yield promising avenue in the field of low frequency mechanical energy harvesting.

This paper reports a simple, quick and cheap method for transferring Pb(Zr,Ti)O 3 (PZT) thin film onto polymer substrate. To achieve a low-cost transfer process, piezoelectric thin film are deposited onto a sacrificial commercial aluminium substrate to target polymer substrate by a wet etching technique. This novel flexible piezoelectric structure was characterized to evaluate its crystal structure and its morphologic properties. This new process should allow to develop novel applications for low frequency vibrations energy harvesting.

It is a habit to invoke Aristotle when dealing, within the arts, with ‘Nature’ – that the Man–Artist (and not only the musician) would be, he says, ‘inclined’ to imitate. It is true, the history of music clearly attests to the temptation and of the ‘pleasure’ (as Aristotle also says) found in mimesis. We know that very lately in history musique concrète gives a new perspective to this question as well as to other questions, and changes the deal: because the sound objects of the world, of the whole world – the ‘noises’ – that needed to be imitated, can now be easily captured through technology, almost in a photographic way, and then they can be gathered, kept, and finally be composed. Hopefully Pierre Schaeffer, its genial inventor, has, concerning the question of nature within new music, a position that tears him apart, which is paradoxical, uncomfortable, fundamental: that the nature that is so easily captured, he does not want to exhibit; to understand the lessons, the hidden musical lessons, he only wants to examine it. This almost heroic model will only be partially followed by the composers (concrète, electroacoustic, acousmatic, anecdotical composers) who have been working during the last sixty years in this passionate domain. At the end of this article, the sketch of a typology, based on musical examples, tries to clarify the way nature is dealt with, when it appears in musique concrète.

With the objective to harvest the airflow energy, flexible PbZrTiO 3 (PZT) thin films have been deposited onto ultra thin aluminium (Al) foil (16 µm).The piezoelectric properties of a PZT/aluminium cantilever have been investigated, and the measurements show d 31 values around 30 pm/V. Due to use of a very lightweight substrate, a very large deflection (in the millimeter range) of the tip of the beam have been observed, which is very promising for actuators applications. In a next step, PZT/aluminium films have been encapsulated with laminated polyethylene terephthalate (PET) in order to increase the flexibility of the device. The obtained structures were subjected to sinusoidal stress at very low frequencies (0.3 to 8 Hz) and the output voltages across a resistive load have been measured and compared to the theory with a good agreement. In addition, an intermediate ruthenium dioxide (RuO 2 ) layer has been used at the PZT/aluminium interface and its influence on the piezoelectric properties and the harvested power has been demonstrated.

International audience; Highly flexible lead zirconate titanate, Pb(Zr,Ti)O3 (PZT), thin films have been realized by modified sol-gel process. The transverse piezoelectric coefficient d31 was determined from the tip displacement of bending-mode actuators made of PZT cantilever deposited onto bare or RuO2 coated aluminium substrate (16 μm thick). The influence of the thickness of ruthenium dioxide RuO2 and PZT layers was investigated for Pb(Zr0.57Ti0.43)O3. The modification of Zr/Ti ratio from 40/60 to 60/40 was done for 3 μm thick PZT thin films onto aluminium (Al) and Al/RuO2 substrates. A laser vibrometer was used to measure the beam displacement under controlled electric field. The experimental results were fitted in order to find the piezoelectric coefficient. Very large tip deflections of about 1 mm under low voltage (∼8 V) were measured for every cantilevers at the resonance frequency (∼180 Hz). For a given Zr/Ti ratio of 58/42, it was found that the addition of a 40 nm thick RuO2 interfacial layer between the aluminium substrate and the PZT layer induces a remarkable increase of the d31 coefficient by a factor of 2.7, thus corresponding to a maximal d31 value of 33 pC/N. These results make the recently developed PZT/Al thin films very attractive for both low frequency bending mode actuating applications and vibrating energy harvesting.

International audience; Inflatable structures made of modem textile materials with important mechanical characteristics can be inflated at high pressure (up to a several hundreds of kPa). They can be used as strong building elements thanks to their mechanical strength. The aim of the paper is to present experimental and analytical studies on the behaviour of inflated fabric panels at high pressure and submitted to bending loads. It is shown that inflatable structures cannot be viewed as ordinary plates or beams, because their deformation pattern is quite different. Experiments show that their behaviour depends on the applied load, the inflation pressure, and the constitutive law of the fabrics. Equilibrium equations are written in the deformed state to take into account the influence of geometrical stiffness and the following forces. A Timoshenko's beam theory must be used because sections of the panels do not satisfy the usual Bernoulli's beam theory. A new inflatable beam theory is developed. Wrinkling loads are derived from equilibrium equations. Deflections satisfy the fact that the compliance of the inflatable panel is the sum of the beam compliance and of the yarn compliance. Comparisons between the results of our modelling and experimental results are shown and prove the accuracy of this theory on the mechanical strength of inflatable structures at high pressure.

International audience; The VIC method consists in finding the analytical contour by fitting the boundary of the objet in the picture as best as possible. It has been used for shape measurement of an inflatable beam submitted to a transverse wind in the CSTB wind tunnel in Nantes. The principle and the main equations of the method are recalled. The originality of this study is that the equation of the contour is deduced from the analytical expression of the deformation of an inflatable beam under a distributed constant (aerodynamic) load. This acts as a powerful mechanical-based filter and leads straightforwardly to the researched mechanical properties of the textile membrane.

A flow cytometric method (FCM) was used to detect and accurately enumerate a polycyclic aromatic hydrocarbon-degrading bacterial strain, Sphingomonas sp. 107, inoculated into a soil sample artificially contaminated with pyrene. To compare the FCM method with colony forming unit (CFU) assays, a rifampicin-resistant Sphingomonas sp. 107 was obtained which could be distinguished from the indigenous microflora, since there was no organism resistant to rifampicin in the soil that could transform indole to indigo (naphthalene dioxygenase activity). By combining light-scattering profiles (i.e., morphological properties), ethidium bromide influx (i.e., cell wall permeability), and fluorescence in situ hybridization against the 16S rRNA (i.e., detection specificity), we could enumerate the bacterial population of interest from the indigenous microflora and soil debris during the biotreatment. The FCM technique revealed that the number of inoculated Sphingomonas cells decreased gradually for 15 days of incubation before reaching a steady level of 7 to 12 × 105cells·g-1of soil. Similar values were obtained with the CFU assay. During this period, pyrene concentration decreased from 632 to 26 mg·kg-1of dry soil. The FCM detection was improved by adding blocking reagent to the hybridization buffer to minimize the non-specific attachment of the fluorescent probe to soil particles. Combined with the improvements in probe technology, FCM detection was shown to be a good alternative to the conventional culture methods for the analysis of bacterial populations in environmental samples. This technique could be potentially useful for the detection of microorganisms that grow poorly in culture.Key words: polycyclic aromatic hydrocarbons, Sphingomonas, bioremediation, soil, laser flow cytometry.

A rapid method was developed for detecting in soil Desulfitobacterium frappieri strain PCP-1, an anaerobic gram-positive bacterium, isolated from a methanogenic consortium degrading pentachlorophenol. The method involved the establishment of a protocol for extracting total DNA from soil with the least contamination, and the use of the polymerase chain reaction (PCR) to detect strain PCP-1 with primers targeted with PCP-1 16S rRNA. To optimize the DNA extraction conditions, a glass mill homogenizer and a low-salt buffer containing polyvinylpolypyrrolidone were used on a black soil rich in organic matter. Recovered DNA was further purified with phenol/chloroform extractions, ammonium acetate precipitation and a G200 Sephadex gel-filtration column. DNA was extracted from soil supplemented with different concentrations of PCP-1 cells. Detection of PCP-1 was by PCR. The limit of detection was 800 added PCP-1 cells/g dry soil. This level of detection was achieved when the T4 gene-32 protein and 1 microgram soil DNA were added to the PCR mixture followed by a nested PCR. This method is quick, sensitive, and can process several samples at the same time.

Specific detection and accurate enumeration of microorganisms in the environment have been hampered by the lack of suitable techniques. A three-parameter flow cytometric method (FCM) was developed to detect quantitatively Sphingomonas sp. strain 107 inoculated into soil samples. By combining light scattering profiles (i.e., morphological properties), ethidium bromide (EtBr) influx (i.e., wall permeability), and fluorescence in situ hybridization against the 16S rRNA (i.e., detection specificity), we could accurately discriminate the bacterium of interest from the indigenous microflora and soil debris. EtBr was used, first, to determine the optimal cell wall permeabilization treatment to allow oligonucleotide probes to enter the bacterial cells and, second, to achieve clear discrimination of fixed cells from debris in soil samples. This method allowed effective qualitative and quantitative analysis by fluorescence in situ hybridization. The results showed that the detection threshold by FCM was 3 × 104 cells/g of dry soil. Cell counts deduced from FCM analysis were similar to those obtained by the colony forming unit assay when soils contained fewer than 3 × 106 cells/g dry soil. This method should be useful for either quantitative monitoring of microorganisms inoculated in contaminated soil samples during bioremediation or detecting known bacterial strains in environmental samples. Cytometry 27:224–232, 1997. © 1997 Wiley-Liss, Inc.

International audience; Inflatable tubes must be pressurized before they are able to resist to external loadings. While there are many studies dedicated to the behavior of inflated tubes under bending or twisting, few results are available on the inflating stage when the beam is only submitted to the internal pressure. In this paper, an exact solution is proposed for a cylindrical tube made of an orthotropic membrane, with the orthotropy axes parallel to the circumferential and longitudinal directions of the cylinder, and undergoing finite deformations under internal pressure. The solution of the problem amounts to solving a cubic equation and analytical relations are given for the inflated geometry as well as the resultant stresses in the membrane. Numerical results are shown to compare very well with those obtained from a finite element code.

International audience; In this paper, an analytical solution is proposed for a pressurized cylindrical tube made of an orthotropic membrane, with the orthotropy directions oriented at an arbitrary angle, not necessarily parallel to the tube axis. The formulation is made in the framework of finite deformations and results in a system of three non-linear equations, giving the final radius, length and rotation of the cross-sections of the tube, in the deformed configuration. The set of equations is solved for balanced and unbalanced materials, with various internal pressures and orientations of the membrane. The numerical results obtained are shown to agree very well with those of an independent finite element code.

Human machine operators are often subject to extreme shocks and vibrations while operating production machines and vehicles. To assess the impact on perceived comfort objectively, a wireless vibration monitoring system is needed that measures whole-body vibrations directly on the human body. To this end, we have developed a wireless body area network consisting of low-power vibration sensor nodes that have a small and ergonomic form factor and that are easy to install. Furthermore, we have validated the BAN along with the necessary post-processing of the raw vibration signals on a real industrial case, i.e. the driver of a forklift. Our system proves to be instrumental in optimizing critical tuning parameters of a machine, exemplified by the transmission control parameters of a forklift.

International audience; Inflatable structures are under increasing development in various domains. Their study is often carried out by using 3D membrane finite elements and for static loads. There is a lack of knowledge in dynamic conditions, especially for simple and accurate solutions for inflatable beams. This paper deals with the research on the natural frequencies of inflatable Timoshenko beams by an exact method: the continuous element method (CEM), and by the classical finite element method (FEM). The dynamic stiffness matrix D(ω) is here established for an inflatable beam; it depends on the natural frequency and also on the inflation pressure. The stiffness and mass matrixes used in the FEM are deduced from D(ω). Natural frequencies and natural modes of a simply supported beam are computed, and the accuracy of the CEM is checked by comparisons with the finite element method and also with experimental results.