Negative Diamagnetic Anisotropy and Birefringence of Cellulose Nanocrystals

We report magnetic birefringence measurements up to high fields (17.5 T) of dilute aqueous suspensions of rod-like cellulose nanocrystals with well characterized distributions of lengths, widths and thicknesses. We compare these data with three models, one with colinear (1), one with perpendicular cylindrically symmetric tensors for diamagnetic susceptibility and refractive index (2) and one with biaxial diamagnetic anisotropy (3). We find that taking into account polydispersities of length, width, and thickness is essential for accurate fitting and that model 1 is the most appropriate, presumably because of the twisting of the suspended nanocrystal along their long axis. The best-fitted susceptibility anisotropy was <i>Δχ</i>_{<i>z</i>(<i>xy</i>)} = χ_<i>zz</i>–(χ_<i>xx</i>+χ_<i>yy</i>)/2 = −2.44 × 10^–6 when considering only the crystalline core of nanocrystals and, more appropriately, <i>Δχ</i>_{<i>z</i>(<i>xy</i>)} = −0.95 × 10^–6 when including crystalline core and skin. The latter value is slightly higher than <i>Δχ</i>_{<i>z</i>(<i>xy</i>)} = −0.68(5) × 10^–6 deduced from estimations using Pascal’s additivity law. The specific birefringence of the nanocrystals in water was found to be <i>δn</i>₀ = +0.120(2), which is well accounted for by the intrinsic birefringence of crystalline cellulose (<i>δn</i>₀^intr = <i>n</i>_∥–<i>n</i>_⊥ = +0.0744) and the birefringence arising from the slender shape of nanocrystals

Effect of Professional and Extra-Professional Exposure on Seroprevalence of SARS-CoV-2 Infection among Healthcare Workers of the French Alps: A Multicentric Cross-Sectional Study

We aimed to report SARS-CoV-2 seroprevalence after the first wave of the pandemic among healthcare workers, and to explore factors associated with an increased infection rate. We conducted a multicentric cross-sectional survey from 27 June to 31 September 2020. For this survey, we enrolled 3454 voluntary healthcare workers across four participating hospitals, of which 83.4% were female, with a median age of 40.6 years old (31.8–50.3). We serologically screened the employees for SARS-CoV-2, estimated the prevalence of infection, and conducted binomial logistic regression with random effect on participating hospitals to investigate associations. We estimated the prevalence of SARS-CoV-2 infection at 5.0% (95 CI, 4.3%–5.8%). We found the lowest prevalence in health professional management support (4.3%) staff. Infections were more frequent in young professionals below 30 years old (aOR = 1.59, (95 CI, 1.06–2.37)), including paramedical students and residents (aOR = 3.38, (95 CI, 1.62–7.05)). In this group, SARS-CoV-2 prevalence was up 16.9%. The location of work and patient-facing role were not associated with increased infections. Employees reporting contacts with COVID-19 patients without adequate protective equipment had a higher rate of infection (aOR = 1.66, (95 CI, 1.12–2.44)). Aerosol-generating tasks were associated with a ~1.7-fold rate of infection, regardless of the uptake of FFP2. Those exposed to clusters of infected colleagues (aOR = 1.77, (95 CI, 1.24–2.53)) or intra-familial COVID-19 relatives (aOR = 2.09, (95 CI, 1.15–3.80)) also had a higher likelihood of infection. This report highlights that a sustained availability of personal protective equipment limits the SARS-CoV-2 infection rate to what is measured in the general population. It also pinpoints the need for dedicated hygiene training among young professionals, justifies the systematic eviction of infected personnel, and stresses the need for interventions to increase vaccination coverage among any healthcare workers

Epidemiology of genital herpes simplex virus infections in a community-based sample in France: Results of the HERPIMAX study

Objective: The objective of this study was to provide information on the prevalence of herpes simplex infections in the general population in Europe. Goals: The goals of this study were to determine the prevalence of clinically probable genital herpes and the relationship between serotype and clinical expression in a French community-based sample. Study: A total of 4410 subjects chosen at random were serotyped for herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). Data on symptoms were obtained by questionnaire allowing retrospective diagnosis of clinically probable genital herpes. Results: Questionnaire data and serotype were available for 3192 subjects. Seroprevalences of HSV-1 and HSV-2 were 65.6% and 15.5%, respectively. Prevalence of clinically probable genital herpes was 11.8%, identified in 11.1% of HSV-1-positive subjects and 26.8% of HSV-2-positive subjects, with a lower prevalence in those coinfected with both virus types. Conclusions: Clinically probable genital herpes was observed in one fourth of subjects with HSV-2 infections and in some subjects with HSV-1 infection. Coinfection with HSV-1 appeared to protect against symptom expression in subjects infected with HSV-2. Copyright © 2005, American Sexually Transmitted Diseases Association. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Multicenter Trials Need To Use the Same Assay for Hepatitis C Virus Viral Load Determination▿

This study, involving 20 laboratories and using currently available assays for hepatitis C virus RNA quantification, demonstrated that differences in viral load values are due not to interlaboratory variations but rather to the nature of the assay itself. This underlines the importance of using the same assay in multicenter studies or when monitoring antiviral therapy

Dégradation physique des sols agricoles et forestiers liée au tassement : principaux résultats du projet GESSOL ADD-DST

National audiencePhysical degradation of agricultural and forest soils due to compaction is an important concern for the actors in agriculture, forest and environment. Many questions are still pending on the importance of this degradation, the evaluation of its impact on environment, the effect of changes of climate and practices, its natural remediation. The DST (Agricultural and Forest Soil Degradation induced by Compaction ?) project has proposed a research action on soil compaction in metropolitan France in order to : quantify the impacts of soil compaction on important soil environmental functions ; identify the conditions leading to compaction ; prevent the occurrence of these conditions ; monitor the evolution of soil structure after compaction. The project was structured in five working packages : impact, prediction, prevention, follow-up and cartography. It was based on modelling (hydrology, soil deformation, soil-crop interactions models) to study the occurrence of compaction and its impacts on crop growth and the environment. It also aimed at developing non-destructive methods to monitor soil structure deformation. The project associated research laboratories working in agriculture, geophysics or civil engineering and extension services members and was also based on field and laboratory experimentations, performed in various conditions (field crops, vineyards, forests). Mains results concerned : (i) impacts of compaction, as we demonstrated the existence of a threshold value for the structural void ratio (0,15 m3m3 in loamy soils) beyond which crop performances and hydrological properties are systematically affected ; (ii) modelling, with a 2-D model of soil deformation ; (iii) compaction assessment, based on non-destructive geophysical methods ; (iv) prevention of compaction, with a predictive model of soil water content and (v) mapping of compaction risks in France, based on the knowledge acquired during the project.La degradación física de los suelos agrícolas y forestales ligada a la compactación durante los pasajes de maquinarias está una preocupación importante de los actores de la agricultura y de la gestión forestal. Pero más allá de este círculo, concierne igualmente todos los que se preocupan de las consecuencias ambientales de la agricultura y de la gestión forestal. En efecto, la compactación de los suelos modifica sus propiedades y así varias funciones importantes para los procesos tales que erosión hídrica, denitrificación, almacenamiento del carbono, preservación de la biodiversidad. En este cuadro, el proyecto DST propuso cinco direcciones de investigación : impacto, previsión, prevención, seguimiento y cartografía de la compactación. Se basó en la utilización de modelos de compactación de los suelos y de funcionamiento del sistema para estudiar las consecuencias sobre los cultivos y el medio ambiente, vía la modificación de las propiedades (almacenamiento, transferencia, mecánicas) de los suelos. Este proyecto transversal, que asocia laboratorios de investigación que trabajan en agricultura, geofísica, o ingeniera civil y los organismos profesionales, se apoyo también sobre experimentaciones variadas, en laboratorio y en el campo. En este articulo se presenta los principales resultados que conciernen : (i) el impacto de la compactación, con la puesta en evidencia de un umbral de índice de vacios en suelo limoso, más allá del cual las performances de los cultivos y las propiedades hidrodinámicas están, desde luego, impactadas, (ii) la modelización, el proyecto desemboco sobre la realización de un modelo 2-D de previsión de la deformación de los suelos, (iii) el seguimiento, con la evaluación de métodos geofísicos, no destructivos que permiten la cartografía de las zonas compactadas, (iv) la prevención, a través del desarrollo de una herramienta de previsión de la humedad del suelo y de los días disponibles y (v) la cartografía de las zonas con riesgos en Francia.La dégradation physique des sols agricoles et forestiers liée au tassement lors des passages d’engins est une préoccupation importante des acteurs de l’agriculture et de la forêt. Mais au-delà de ce cercle, elle concerne également tous ceux qui se préoccupent des conséquences environnementales de l’agriculture et de la gestion forestière. En effet, le tassement des sols modifie a des conséquences lourdes sur plusieurs processus tels que l’érosion hydrique, la dénitrification, le stockage du carbone, la préservation de la biodiversité, la production. Dans ce cadre, le projet DST (Dégradation physique des Sols agricoles et forestiers liée au Tassement) proposait cinq volets de recherche : impact, prévision, prévention, suivi et cartographie du tassement en France métropolitaine. Il a reposé sur l’utilisation de modèles de tassement des sols et de fonctionnement du système sol/plante pour étudier les conséquences sur les cultures et l’environnement, via la modification des propriétés (stockage, transfert, mécaniques) des sols. Ce projet transversal, associant des laboratoires de recherche travaillant en agriculture, en géophysique ou en génie civil et des organismes professionnels, s’est aussi appuyé sur des expérimentations variées, en laboratoire et sur le terrain. Les principaux résultats sont présentés dans cet article. Ils concernent : (i) l’impact du tassement, avec la mise en évidence d’un seuil d’indice des vides en sol limoneux (0,15 m3.m 3 dans les sols limoneux), au-delà duquel les performances des cultures et les propriétés hydrodynamiques sont à coup sûr affectées, (ii) la modélisation, le projet ayant débouché sur la mise au point d’un modèle 2-D de prévision de la déformation des sols, (iii) le suivi, avec l’évaluation de méthodes géophysiques, non destructrices, permettant la cartographie des zones tassées, (iv) la prévention, à travers le développement d’un outil de prévision de l’humidité du sol et des jours disponibles et, (v) la cartographie des zones à risques en France

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

Cellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.Cell

Impact on disease mortality of clinical, biological, and virological characteristics at hospital admission and overtime in COVID‐19 patients

International audienc