Polytech Lille

Sand, rice, sugar, snow, cement... Although ubiquitous in our daily lives, granular media still challenge engineers and fascinate researchers. This book provides the state-of-the-art of the physics of granular media and recent advances in the field. The book presents the fundamental properties of granular materials: interactions between grains; solid, liquid and gaseous behaviours; coupling with a fluid; and sediment transport and formation of geological structures. Descriptions of the phenomena combine qualitative and formal arguments, coming from areas as diverse as elasticity, plasticity, statistical physics, fluid mechanics and geomorphology. Many examples of the astonishing behaviours of granular media are presented, including avalanches, segregation, dune song and quicksand. This book is ideal for graduate students and researchers in physics, applied mathematics and engineering.

An experimental study of the migration of dilute suspensions of particles in Poiseuille flow at Reynolds numbers $\hbox{\it Re}\,{=}\,67\hbox{--}1700$ was performed, with a few experiments performed at $\hbox{\it Re}$ up to 2400. The particles used in the majority of the experiments were neutrally buoyant spheres with diameters $d$ yielding a ratio of pipe to particle diameter in the range $D/d \,{=}\, 8\hbox{--}42$ . The volume fraction of solids was less than 1% in all cases studied. The results of G. Segré & A. Silberberg ( J. Fluid Mech. 14 , 136, 1962) have been extended to show that the tubular pinch effect in which particles accumulate on a narrow annulus is moved toward the wall as $\hbox{\it Re}$ increases. A careful comparison with asymptotic theory for Poiseuille flow in a channel was performed. Another inner annulus closer to the centre, and not predicted by this asymptotic theory, was observed at elevated $\hbox{\it Re}$ . As $\hbox{\it Re}$ is increased, the distribution of particles over the cross-section of the tube at the measurement location, lying at a distance $L \doteq 310 D$ from the entrance, changes from one centred at the annulus predicted by the theory to one with the particles primarily on the inner annulus. The case of slightly non-neutrally buoyant particles was also investigated. A particle trajectory simulation based on asymptotic theory was performed to facilitate the comparison of theory and the experimental observations.

Sand, rice, sugar, snow, cement ... Although ubiquitous in our daily lives, granular media still challenge engineers and fascinate researchers. This book provides the state-of-the-art of the physics of granular media and recent advances in the field. The book presents the fundamental properties of granular materials: interactions between grains; solid, liquid and gaseous behaviours; coupling with a fluid; and sediment transport and formation of geological structures. Descriptions of the phenomena combine qualitative and formal arguments, coming from areas as diverse as elasticity, plasticity, statistical physics, fluid mechanics and geomorphology. Many examples of the astonishing behaviours of granular media are presented, including avalanches, segregation, dune song and quicksand. This book is ideal for graduate students and researchers in physics, applied mathematics and engineering.

A Bacillus subtilis derivative was obtained from strain ATCC 6633 by replacement of the native promoter of the mycosubtilin operon by a constitutive promoter originating from the replication gene repU of the Staphylococcus aureus plasmid pUB110. The recombinant strain, designated BBG100, produced up to 15-fold more mycosubtilin than the wild type produced. The overproducing phenotype was related to enhancement of the antagonistic activities against several yeasts and pathogenic fungi. Hemolytic activities were also clearly increased in the modified strain. Mass spectrometry analyses of enriched mycosubtilin extracts showed similar patterns of lipopeptides for BBG100 and the wild type. Interestingly, these analyses also revealed a new form of mycosubtilin which was more easily detected in the BBG100 sample. When tested for its biocontrol potential, wild-type strain ATCC 6633 was almost ineffective for reducing a Pythium infection of tomato seedlings. However, treatment of seeds with the BBG100 overproducing strain resulted in a marked increase in the germination rate of seeds. This protective effect afforded by mycosubtilin overproduction was also visualized by the significantly greater fresh weight of emerging seedlings treated with BBG100 compared to controls or seedlings inoculated with the wild-type strain.

This paper focuses on the study of the effect of chemical treatments of fibers by alkalization on the flexural properties of polyester matrix composite reinforced with natural fibers. The used reinforcement consists of Alfa fiber, extracted from the plant Stippa tenacissima from Hodna Region (Algeria). Alfa fibers are subjected to alkali treatments with NaOH at 1, 5 and 10% for a period of 0, 24, and 48 h to 28 °C. The composites reinforced with layers of Alfa random costituente a rate of 40% by weight. Influence of alkaline treatments on the flexural properties is studied to determine the optimum conditions of alkaline treatment. The experimental results show that the bending behavior of composites made from alkali treated fibers are better compared to the untreated fiber composite, For a fiber processing Alfa 10% NaOH in 24 h, the flexural strength and flexural modulus improved by 23 MPa to 57 MPa and from 1.16 to 3.04 GPa. However, the flexural properties of composites decreased after alkali treatment with 5% NaOH for 48 h. This is mainly due to the reduction of lignin that binds the cellulose fibrils together.

Acute heart failure (AHF) due to peripartum cardiomyopathy (PPCM) provides a challenge for treating physicians. Moreover, in patients still pregnant, therapeutic interventions need always to consider the health of both the mother and the foetus. Especially challenging are severe forms of PPCM, as the mortality of these women is quite high. The use of inotropic drugs and mechanical circulatory support devices may be necessary in the initial phase of severe forms of acute PPCM. Many patients, after initial stabilization, recover LV function.1-3 Unfortunately, some patients need further mechanical circulatory support or urgent heart transplantation despite maximal therapy. In addition, the time frame and extent of recovery are unpredictable, and patients may suffer from cardiac arrest due to ventricular fibrillation in the first months after diagnosis.4 The clinical course may be further aggravated by atrial and/or ventricular thrombus formation with subsequent cardio-embolic complications. As evidence-based data from randomized clinical trials are scarce, in this practical guidance we summarize recent data and clinical experience in the treatment of patients with severe acute PPCM to help physicians in the diagnosis, acute treatment, and long-term management of these young critically ill patients. The Working Group on PPCM of the Heart Failure Association (HFA) of the European Society of Cardiology (ESC) recently proposed a new simplified definition of PPCM as an idiopathic cardiomyopathy frequently presenting with heart failure secondary to LV systolic dysfunction (LVEF <45%) towards the end of pregnancy or in the months following delivery, if no other cause of heart failure is found.1 Since no specific test to confirm PPCM exists, it remains a diagnosis of exclusion. In particular, aggravation of pre-existing heart disease by pregnancy-mediated haemodynamic changes should be differentiated from PPCM. The pathophysiology of PPCM remains poorly understood. The current status of knowledge of the pathophysiological mechanisms of PPCM has been published elsewhere.3 A ‘two-hit’ model of angiogenic imbalance in the heart during the peripartal period has recently been proposed, combining systemic antiangiogenic signals during late pregnancy and host susceptibility through insufficient local proangiogenic defences in the heart.1-3, 5 Angiogenic imbalance can further be triggered by oxidative stress activating cathepsin D, a protease responsible for the cleavage of the nursing hormone prolactin into the angiostatic and proapoptotic 16 kDa subfragment.4, 6 Most patients admitted with PPCM present typical symptoms of AHF associated with signs of congestion. Because early signs and symptoms of heart failure in PPCM patients may mimic physiological changes occurring during/after pregnancy, delayed diagnosis may occur. The differential diagnosis of acute PPCM includes myocarditis, pre-existing cardiomyopathy, valve disease, or congenital heart disease. In the case of cardiogenic shock, pregnancy-associated myocardial infarction, pulmonary embolism, and amniotic liquid embolism should be immediately ruled out to provide adequate care (Table 1). Earlier onset (during second trimester) Sometimes family history Consider MRI Consider genetic test MRI Consider myocardial biopsy As for any AHF, initial evaluation of patients with suspected acute PPCM includes two parts, which should be performed simultaneously to allow timely diagnosis and treatment delivery: evaluation of cardiopulmonary distress; and confirmation of the diagnosis with additional tests. Evaluation of cardiopulmonary distress is crucial because it will influence subsequent treatment and patients' allocation. The presence of criteria defining cardiopulmonary distress should lead to intensive cardiac care unit admission: haemodynamic instability (systolic blood pressure <90 mmHg, heart rate >130 b.p.m. or <45 b.p.m.), respiratory distress (respiratory rate >25/min; peripheral oxygen saturation <90%), or signs of tissue hypoperfusion with abnormal cellular oxygen metabolism (increased blood lactate >2.0 mmol/L; low central–venous oxygen saturation <60%, if available; altered mental state; cold, clammy, mottled skin; oliguria <0.5 mL/kg/h).1, 7 Since PPCM is a diagnosis of exclusion, several additional tests should be performed (see below). This should not delay the start of treatment, which should be instituted as soon as AHF is confirmed. An ECG should be performed in all patients with suspected PPCM as it has high negative predictive value and might help in identifying the cardiac origin of dyspnoea. Indeed, despite the fact that no specific ECG pattern for PPCM seems to exist, at initial evaluation, the ECG is rarely normal and repolarization abnormalities are common.4, 8, 9 Patients with acute PPCM usually have elevated plasma concentrations of natriuretic peptides.10, 11 Measurement of natriuretic peptides may help during screening for identifying a cardiac origin of dyspnoea, although it does not help in the differentiation of PPCM from other cardiomyopathies. More specific biomarkers would be helpful to allow a faster and more reliable diagnosis of PPCM, but these are yet to be adequately defined. Echocardiography is indicated as soon as possible, in all cases of suspected PPCM to confirm the diagnosis, assess concomitant or pre-existing cardiac disease, exclude complications of PPCM (e.g. LV thrombus), and obtain prognostic information. Cardiac magnetic resonance imaging (MRI) is not routinely needed, but can be performed after stabilization in cases where additional information, not available with echocardiography, is needed. However, administration of gadolinium to assess late enhancement should be avoided until after delivery, unless absolutely necessary. Endomyocardial biopsy does not add any diagnostic or prognostic information in the case of PPCM but can be used to exclude acute myocarditis after delivery. Only a few PPCM cases have been related to myocarditis so far,12 but myocarditis may underlie cases of dilated cardiomyopathies and AHF that can occur or worsen during pregnancy, and specific immunosuppressive or immune-modulatory treatments may be helpful for some forms of myocarditis.13 The management of heart failure around pregnancy is challenging (Box 1), and, in the absence of evidence-based data, the initial management of patients with PPCM is similar to the treatment of AHF of other aetiologies.14, 15 Interdisciplinary approaches of cardiologists, intensivists, obstetricians, neonatologists, anaesthetists, and cardiac surgeons are necessary in cases of severe AHF. Pre-specified protocols of interdisciplinary work-up of these patients are helpful (Figure 1).16 Timely diagnosis and treatment delivery are crucial. Figure 2 summarizes the recommended treatment algorithm for patients with acute PPCM. Of note, the initial treatment of patients with severe forms of acute PPCM is significantly different from that of stable patients. Patients with signs of cardiopulmonary distress and/or circulatory shock need rapid and more aggressive therapy and should be admitted to the intensive cardiac care unit. Initial therapy includes five main elements: optimization of the preload; optimization of oxygenation; restoration of haemodynamics with inotropes and/or vasopressors; urgent delivery if heart failure occurs during pre-partum; and consideration of adjunctive therapies with bromocriptine (2.5 mg twice daily for 2 weeks followed by 2.5 mg per day for 6 weeks). Optimization of preload includes, depending on the clinical scenario, administration of fluids or diuretics. If there is no sign of overt fluid overload, a fluid challenge (250–500 mL over 15–30 min) is recommended, especially in patients with intravascular depletion secondary to peripartal blood loss or overaggressive diuretic therapy. In the presence of signs of congestion, intravenous diuretics should be administered. In patients with systolic blood pressure >110 mmHg, intravenous vasodilators (e.g. nitrates) should be started. At the same time, oxygenation should be optimized (target peripheral oxygen saturation, SpO2 > 95%). Non-invasive ventilation (NIV) reduces respiratory distress and may decrease intubation and mortality rates.17 Intubation with mechanical ventilation should be considered in the case of altered mental state or persistent hypoxaemia. In the presence of signs of cardiogenic shock, haemodynamics should be rapidly restored to avoid irreversible organ damage. Inotropes and vasopressors may be considered, although the use of catecholamines is associated with adverse effects in patients with advanced heart failure or cardiogenic shock.18, 19 Experimental evidence and clinical experience suggest that catecholamines such as dobutamine are less favourable in PPCM patients due to metabolic compromise.20 Therefore, catecholamines should be avoided whenever possible or used only with extreme caution. Levosimendan, in contrast to dobutamine and adrenaline, does not increase myocardial oxygen demand and may be considered as the preferred inotropic agent as continuous infusion of 0.1 µg/kg/h for 24 h without an initial loading dose (bolus) for patients with severe PPCM.21 A recent small study including 28 patients showed that the use of levosimendan in patients with PPCM induced rapid haemodynamic recovery and profound decongestive effects.22 In case levosimendan is unavailable, dobutamine is the other option, while adrenaline should be avoided. As for other causes of shock, noradrenaline should be the first-line vasopressor. Patients with haemodynamic instability despite treatment should undergo urgent delivery irrespective of gestation duration. Caesarean section with combined spinal and epidural analgesia and involvement of an experienced interdisciplinary team are recommended. The administration of adjunctive therapies with the prolactin blocker bromocriptine has shown promising results in several case series and in a small proof-of-concept study,23 and should be considered for patients with cardiopulmonary distress. The starting dose of bromocriptine is usually 2.5 mg twice daily, but an increased dose may be necessary to lower prolactin levels in selected cases (see below). As thrombo-embolic events have been reported during the use of bromocriptine (albeit mostly at higher dosages), bromocriptine treatment should always be accompanied by at least prophylactic anticoagulation with heparin.24 Anticoagulation with heparin should also be started in all patients with acute PPCM and severely reduced LV systolic function (LVEF ≤35%). Indeed, the combination of reduced EF and the procoagulant activity during the peripartal phase exposes patients to a clinically important risk of cardio-embolic events. In general, patients with severe distress should be transferred early to an experienced centre whenever possible. For patients with persistent haemodynamic instability despite medical treatment, mechanical circulatory support should be considered (see below). Implantation of a mechanical circulatory support should be considered early as a rescue therapy in patients who cannot be stabilized with medical therapy alone. If necessary, a device for temporary support should be implanted in the acute phase, either as ‘bridge-to-recovery’, if ventricular function improves during the subsequent days and weaning can be achieved, or as ‘bridge-to-bridge’, if haemodynamic impairment persists and circulatory support has to be ensured by switching to a more durable (and usually more invasive) device. Because of the higher proportion of patients with at least partial recovery of ventricular function compared with other cardiomyopathies, an initial ‘bridge-to-transplantation’ strategy is seldom necessary. Since several devices exist, and there is little evidence about which device should be preferred;25 we provide here an overview of some devices based on experts' opinion. For the choice of the initial device, several factors should be taken into account (needed haemodynamic support, periprocedural risks, costs), but the oxygenation status of the patient plays a central role. If the patient is adequately oxygenated, percutaneous [e.g. intra-aortic balloon pump (IABP), Impella®] or surgical (e.g. CentriMag®, AbiomedBVS 5000®) devices can be used to restore circulation. In contrast, in the presence of impaired oxygenation, other devices with integrated oxygenation should be used [e.g. TandemHeart®, veno-arterial extracorporeal membrane oxygenation (ECMO)]. Most importantly, as the treatment of patients on mechanical circulatory support is very challenging, the choice of the device should also consider the local availability and the experience of the involved care team (physicians, nurses, and perfusionists). Percutaneous devices offer the advantage of fast and easier placement and removal without the need for open surgery, but complications related to the access site (bleeding, infection, ischaemic limbs) are not uncommon. An IABP provides less haemodynamic support compared with other devices, but on the other hand is easily placed and needs less strict anticoagulation. Given the negative results of the IABP-SHOCK II trial and the lack of data in PPCM, the value of this device in patients with severe PPCM is uncertain, although it is used in selected cases by some centres.26 The Impella® rotary pump is an alternative percutaneous device for temporary support. It is inserted percutaneously from the femoral artery and is placed in the left ventricle through the aortic valve. Depending on the model, it provides a higher degree of haemodynamic support compared with IABP (up to 5 L/min) but is associated with haemolysis and, especially in the context of PPCM, where a procoagulant state is frequent, a stricter anticoagulation regime than for IABP is needed.27 In a small trial in patients with cardiogenic shock complicating myocardial infarction, there was no difference in terms of survival between IABP and Impella®.28 Clinical experience in several PPCM patients with the Impella 3.5 device suggests effective LV support over up to 7–10 days when used as bridge-to-recovery in most patients. The marked decrease in the need for catecholamines may importantly contribute to the beneficial outcome observed in several patients (Figure 3). The TandemHeart® device offers similar haemodynamic support to Impella® (up to 5 L/min) with additional improvement in oxygenation. The placement of this device is performed percutaneously in the catheterization laboratory but it requires a more complex placement with atrial trans-septal puncture. No evidence of improved outcomes in patients with cardiogenic shock receiving TandemHeart® compared with IABP exists.29, 30 Extracorporeal membrane oxygenation with veno-arterial cannulation offers the maximal available haemodynamic effect with biventricular support and additional improvement in oxygenation.31 As increased prolactin levels during ECMO treatment have been reported, which may be specifically detrimental in patients with PPCM,32 effective suppression of prolactin under sequential measurements of prolactin levels could be considered in this particular situation with bromocriptine doses up to 10 mg twice daily. After the initial phase, if no weaning from mechanical circulatory support can be achieved after a maximum of 7–10 days, a switch to a durable device should be planned. As for temporary support, several devices exist and little evidence is available to guide the choice of the optimal device. Special attention should be paid to right ventricular function. In the presence of impaired right ventricular function, a biventricular assist device (BiVAD or total artificial heart) may be chosen (e.g. Berlin Heart EXCOR®). Alternatively, several strategies of transient right ventricular support in patients after left ventricular assist device (LVAD) implantation have been adopted in different centres (e.g. veno-arterial ECMO, Impella® RP, or similar). In patients with preserved right ventricular function, LVADs should be preferred. The most commonly used devices are the continuous-flow axial (HeartMate II®) and centrifugal (HeartWare®) LVADs which have shown promising results in patients with end-stage heart failure.33-35 Given the high likelihood of at least partial recovery of ventricular function in PPCM, temporary devices should always be the preferred initial strategy. Cardiac transplantation is reserved for patients where mechanical circulatory support is not possible or satisfactory ventricular recovery after 6–12 months is not achieved. Post-transplant outcomes in women with PPCM appear to be worse than in other recipients: in particular, women with PPCM show higher mortality, a higher incidence of rejection with shorter graft survival, and higher rates of re-transplantation.36 The initial treatment of patients with confirmed PPCM without cardiopulmonary distress depends on the time point of onset. Patients who present after delivery should be treated according to the ESC guidelines for heart failure.37 For patients presenting during pregnancy, joint cardiac and obstetric care in observance of the ESC guidelines for management of cardiovascular diseases in pregnancy is recommended.38 During pregnancy, ACE inhibitors, ARBs, and renin inhibitors are contraindicated because of foetal toxicity. and can be used After delivery, ACE inhibitors can be but during or should be preferred. an increased risk of foetal are indicated in all patients in stable with the preferred should be avoided during pregnancy and but should be started in stable patients. should be with during pregnancy as may of the for use during pregnancy and are in of the ESC guidelines for management of cardiovascular diseases in in to heart failure therapy should be considered because it has shown promising results with improved LV systolic function and clinical outcomes in several case series and in a small proof-of-concept In the PPCM treatment with ACE inhibitors, and bromocriptine (2.5 mg twice daily for 2 weeks followed by 2.5 mg per day for 6 was associated with favourable A study with patients randomized to either or long-term treatment with bromocriptine has patient and results will be available in the Anticoagulation with heparin should be started in all patients with acute PPCM treated with bromocriptine and in with severely reduced LV systolic function (LVEF diuretics should be when possible after stabilization and when ACE inhibitors, and should be in and not during the first months after recovery of LV and systolic function. of heart failure therapy might be considered if both recovery of ventricular function and normal are achieved. should be according to early treatment with or in with may be considered, as it to be and effective (Figure As have been observed after of the heart failure drugs should be performed under of systolic and obstetric management including on the risk of PPCM with is recommended. knowledge about the and pathophysiology of PPCM, mortality rates are not and may from up to It is that about a of are by ventricular mostly occurring during the first 6 and optimal management may a of impaired ventricular function is associated with increased risk of ESC guidelines for the treatment of heart failure implantation of an for in patients with heart failure and despite optimal treatment or for secondary in patients with ventricular haemodynamic In the context of PPCM, where young women with the for recovery of ventricular function are about implantation of an should be taken with caution. After diagnosis of PPCM, are with the about the subsequent of ventricular function. Therefore, the related of to an or not may be very reported recovery of LV function in at least of patients 6 months after However, a study reported delayed recovery 6 in a proportion of A recent study from the showed recovery of LV function in of patients and partial recovery in over a of delayed recovery over 6 months In this women showed lower rates of recovery compared with and diagnosis was a of In a and low LV of was In of these data, early implantation of an in patients with PPCM is not However, of implantation the time point when further recovery of ventricular function is exposes young to an risk of cardiac such as the are an alternative for the of cardiac in the first months after diagnosis, until a about implantation can be A study reported experience with the in patients with PPCM and severely reduced LV function. out of women with PPCM and the early after During a period of days, adequate for ventricular fibrillation in patients without any shock delivery the first months of diagnosis.4 results may suggest the of the due to the risk for ventricular for at least months after diagnosis to allow recovery from severely reduced LV function. In patients without recovery despite months on optimized heart failure a for the prophylactic implantation of an In patients without or are recommended. an alternative to in these young patients. avoid intravascular and the of to and lead the other can provide and might not be the optimal choice for patients with ventricular by In patients with heart despite optimal medical therapy for at least months and is although no have the value of in patients with PPCM. improvement of LV function in two PPCM patients device implantation because of persistent LV dysfunction was to the current ESC guidelines on in patients with heart persistent and >130 should be in patients with complex with may be no data on device therapy in patients with PPCM exist, for the device therapy may be as in patients with dilated for and for with and and of from the and from from and the and from and from and the from and and as a of the and/or from and the other no of

ABSTRACT Customer loyalty has become a topical issue in research and practice due to its proven dominance in a hotel organization's success. The present research adds to the body of knowledge in services marketing in the hospitality industry by improving understanding of the relationships among customer loyalty, customer satisfaction, and image. This research identifies the factors of image and customer satisfaction that are positively related to customer loyalty in hotels. Research findings from the data collected from chain hotels indicate that hotel image and customer satisfaction with the performance of housekeeping, reception, food and beverage, and price are positively correlated to customer loyalty. Performance of housekeeping, however, was found to be one of the most important considerations for customers of hotel chains. KEYWORDS: Customer satisfactioncustomer loyaltyimageservice marketingservice quality

Since the 2006 European ban on the use of antibiotics as growth promoters in animal feed, numerous studies have been published describing alternative strategies to prevent diseases in animals. A particular focus has been on prevention of necrotic enteritis in poultry caused by Clostridium perfringens by the use of microbes or microbe-derived products. Microbes produce a plethora of molecules with antimicrobial properties and they can also have beneficial effects through interactions with their host. Here we review recent developments in novel preventive treatments against C. perfringens-induced necrotic enteritis in broiler chickens that employ yeasts, bacteria and bacteriophages or secondary metabolites and other microbial products in disease control.

First-principles calculations based on density functional theory are performed to study the magnetic, electronic, and optical properties of ZnO doped with 6.25%, 12.5%, and 18.75% of Cu. The Cu dopants are found spin polarized, and a net magnetic moment of 0.57μB is found for Cu at a composition of 6.25%. The calculations confirm an appreciable band gap reduction in ZnO in agreement with recent experimental results. The analysis of the partial density of states reveals that ferromagnetism and narrowing of ZnO band gap are due principally to the strong p-d mixing of O and Cu.

Most tactile displays currently built rely on pin-based arrays. However, this kind of tactile device is not always appropriate when we need to give the illusion of finely textured surfaces. In this paper, we describe the squeeze film effect between a plate and a finger, and we use this effect to design an ultrasonic tactile plate. The plate is actuated by piezoelectric ceramics. Ultrasonic vibrations are thus produced and are capable of generating the squeeze film effect. This enables us to simulate variable friction on the surface of the plate. In order to identify the squeeze film phenomenon, this study considers the case where a finger, with a planar bottom surface and with epidermal ridges, is placed on a rapidly vibrating plate. The overpressure is calculated and the result enables us to assess the relative coefficient of friction as a function of the vibration amplitude of the plate. Based on this principle, and using both analytic and FE method studies, and given ergonomic and stimulation (squeeze film) requirements, we show that it is possible to design a tactile plate which is capable of giving programmable tactile sensations. We conclude by comparing the results obtained from our simulations with experimental results.

Biological recycling of polyurethanes (PU) is a huge challenge to take up in order to reduce a large part of the environmental pollution from these materials. However, enzymatic depolymerization of PU still needs to be improved to propose valuable and green solutions. The present study aims to identify efficient PU degrading enzymes among a collection of 50 hydrolases. Screenings based on model molecules were performed leading to the selection of an efficient amidase (E4143) able to hydrolyze the urethane bond of a low molar mass molecule and an esterase (E3576) able to hydrolyze a waterborne polyester polyurethane dispersion. Degradation activities of the amidase, the esterase and a mix of these enzymes were then evaluated on four thermoplastic polyurethanes (TPU) specifically designed for this assay. The highest degradation was obtained on a polycaprolactone polyol-based polyurethane with weight loss of 33% after 51 days measured for the esterase. Deep cracks on the polymer surface observed by scanning electron microscopy and the presence of oligomers on the remaining TPU detected by size exclusion chromatography evidenced the polymer degradation. Mixing both enzymes led to an increased amount of urethane bonds hydrolysis of the polymer. 6-hydroxycaproic acid and 4,4'-methylene dianiline were recovered after depolymerization as hydrolysis products. Such building blocks could get a second life with the synthesis of new macromolecular architectures.

In this paper, a coupled constitutive model is proposed for anisotropic damage and permeability variation in brittle rocks under deviatoric compressive stresses. The formulation of the model is based on experimental evidences and main physical mechanisms involved in the scale of microcracks are taken into account. The proposed model is expressed in the macroscopic framework and can be easily implemented for engineering application. The macroscopic free enthalpy of cracked solid is first determined by approximating crack distribution by a second-order damage tensor. The effective elastic properties of damaged material are then derived from the free enthalpy function. The damage evolution is related to the crack growth in multiple orientations. A pragmatic approach inspired from fracture mechanics is used for the formulation of the crack propagation criterion. Compressive stress induced crack opening is taken into account and leads to macroscopic volumetric dilatancy and permeability variation. The overall permeability tensor of cracked material is determined using a micro–macro averaging procedure. Darcy's law is used for fluid flow at the macroscopic scale whereas laminar flow is assumed at the microcrack scale. Hydraulic connectivity of cracks increases with crack growth. The proposed model is applied to the Lac du Bonnet granite. Generally, good agreement is observed between numerical simulations and experimental data. Copyright © 2005 John Wiley & Sons, Ltd.

Non-self-recognition of microorganisms partly relies on the perception of microbe-associated molecular patterns (MAMPs) and leads to the activation of an innate immune response. Bacillus subtilis produces three main families of cyclic lipopeptides (LPs), namely surfactins, iturins and fengycins. Although LPs are involved in induced systemic resistance (ISR) activation, little is known about defence responses induced by these molecules and their involvement in local resistance to fungi. Here, we showed that purified surfactin, mycosubtilin (iturin family) and plipastatin (fengycin family) are perceived by grapevine plant cells. Although surfactin and mycosubtilin stimulated grapevine innate immune responses, they differentially activated early signalling pathways and defence gene expression. By contrast, plipastatin perception by grapevine cells only resulted in early signalling activation. Gene expression analysis suggested that mycosubtilin activated salicylic acid (SA) and jasmonic acid (JA) signalling pathways, whereas surfactin mainly induced an SA-regulated response. Although mycosubtilin and plipastatin displayed direct antifungal activity, only surfactin and mycosubtilin treatments resulted in a local long-lasting enhanced tolerance to the necrotrophic fungus Botrytis cinerea in grapevine leaves. Moreover, challenge with specific strains overproducing surfactin and mycosubtilin led to a slightly enhanced stimulation of the defence response compared with the LP-non-producing strain of B. subtilis. Altogether, our results provide the first comprehensive view of the involvement of LPs from B. subtilis in grapevine plant defence and local resistance against the necrotrophic pathogen Bo. cinerea. Moreover, this work is the first to highlight the ability of mycosubtilin to trigger an immune response in plants.

Bacteriocins produced by lactic acid bacteria (LAB-bacteriocins) may serve as alternatives for aging antibiotics. LAB-bacteriocins can be used alone, or in some cases as potentiating agents to treat bacterial infections. This approach could meet the different calls and politics, which aim to reduce the use of traditional antibiotics and develop novel therapeutic options. Considering the clinical applications of LAB-bacteriocins as a reasonable and desirable therapeutic approach, it is therefore important to assess the advances achieved in understanding their modes of action, and the resistance mechanisms developed by the producing bacteria to their own bacteriocins. Most LAB-bacteriocins act by disturbing the cytoplasmic membrane through forming pores, or by cell wall degradation. Nevertheless, some of these peptides still have unknown modes of action, especially those that are active against Gram-negative bacteria. Regarding immunity, most bacteriocin-producing strains have an immunity mechanism involving an immunity protein and a dedicated ABC transporter system. However, these immunity mechanisms vary from one bacteriocin to another.

In this paper, we propose a multiobserver switching control strategy for robust active fault tolerant fuzzy control (RAFTFC) of variable-speed wind energy conversion systems (WECS) in the presence of wide wind variation, wind disturbance, parametric uncertainties, and sensors faults. The Takagi-Sugeno (TS) fuzzy model with parametric uncertainties is adopted for modeling the nonlinear WECS and establishing fuzzy state observers. Sufficient conditions are derived for robust stabilization in the sense of Taylor series stability and are formulated in linear matrix inequalities (LMIs). Application to WECS, subject to uncertain parameters and sensor faults illustrate the effectiveness of the proposed controllers.

BACKGROUND: Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS: The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classes being found in several fractions. Peptides containing Pro, Hyp, Asp and Glu were concentrated in the UF and NF retentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin-like peptides were present in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene-related peptide (CGRP)-like peptides demonstrated an increase in CGRP-like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin-converting enzyme (ACE)-1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION: Fractionation of an FPH using membrane separation, with a molecular weight cut-off adapted to the peptide composition, may provide an effective means to concentrate CGRP-like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut-off of the membrane only, as is currently done in the literature.

The performance of ten density functional theory (DFT) methods in a prediction of the structure of four clay minerals, in which non-bonding interactions dominate in the layer stacking (dispersive forces in talc and pyrophyllite, and hydrogen bonds in lizardite and kaolinite), is reported. In a set of DFT methods following functionals were included: standard local and semi-local (LDA, PW91, PBE, and RPBE), dispersion corrected (PW91-D2, PBE-D2, RPBE-D2, and vdW-TS), and functionals developed specifically for solids and solid surfaces (PBEsol and AM05). We have shown that the standard DFT functionals fail in the correct prediction of the structural parameters, for which non-bonding interactions are important. The remarkable improvement leading to very good agreement with experimental structures is achieved if the dispersion corrections are included in the DFT calculations. In such cases the relative error for the most sensitive lattice vector c dropped below 1%. Very good performance was also observed for both DFT functionals developed for solids. Especially, the results achieved with the PBEsol are qualitatively similar to those with DFT-D2.

Abstract The enzymatic conversion of plant biomass has been recently revolutionized by the discovery of lytic polysaccharide monooxygenases (LPMOs) that carry out oxidative cleavage of polysaccharides. These very powerful enzymes are abundant in fungal saprotrophs. LPMOs require activation by electrons that can be provided by cellobiose dehydrogenases (CDHs), but as some fungi lack CDH-encoding genes, other recycling enzymes must exist. We investigated the ability of AA3_2 flavoenzymes secreted under lignocellulolytic conditions to trigger oxidative cellulose degradation by AA9 LPMOs. Among the flavoenzymes tested, we show that glucose dehydrogenase and aryl-alcohol quinone oxidoreductases are catalytically efficient electron donors for LPMOs. These single-domain flavoenzymes display redox potentials compatible with electron transfer between partners. Our findings extend the array of enzymes which regulate the oxidative degradation of cellulose by lignocellulolytic fungi.

Nonribosomal peptides (NRPs) are molecules produced by microorganisms that have a broad spectrum of biological activities and pharmaceutical applications (e.g., antibiotic, immunomodulating, and antitumor activities). One particularity of the NRPs is the biodiversity of their monomers, extending far beyond the 20 proteogenic amino acid residues. Norine, a comprehensive database of NRPs, allowed us to review for the first time the main characteristics of the NRPs and especially their monomer biodiversity. Our analysis highlighted a significant similarity relationship between NRPs synthesized by bacteria and those isolated from metazoa, especially from sponges, supporting the hypothesis that some NRPs isolated from sponges are actually synthesized by symbiotic bacteria rather than by the sponges themselves. A comparison of peptide monomeric compositions as a function of biological activity showed that some monomers are specific to a class of activities. An analysis of the monomer compositions of peptide products predicted from genomic information (metagenomics and high-throughput genome sequencing) or of new peptides detected by mass spectrometry analysis applied to a culture supernatant can provide indications of the origin of a peptide and/or its biological activity.

Although being one of the most vulnerable and perishable products, fish and other seafoods provide a wide range of health-promoting compounds. Recently, the growing interest of consumers in food quality and safety issues has contributed to the increasing demand for sensitive and rapid analytical technologies. Several traditional physicochemical, textural, sensory, and electrical methods have been used to evaluate freshness and authentication of fish and other seafood products. Despite the importance of these standard methods, they are expensive and time-consuming, and often susceptible to large sources of variation. Recently, spectroscopic methods and other emerging techniques have shown great potential due to speed of analysis, minimal sample preparation, high repeatability, low cost, and, most of all, the fact that these techniques are noninvasive and nondestructive and, therefore, could be applied to any online monitoring system. This review describes firstly and briefly the basic principles of multivariate data analysis, followed by the most commonly traditional methods used for the determination of the freshness and authenticity of fish and other seafood products. A special focus is put on the use of rapid and nondestructive techniques (spectroscopic techniques and instrumental sensors) to address several issues related to the quality of these products. Moreover, the advantages and limitations of each technique are reviewed and some perspectives are also given.