A Glassy Carbon Electrode Modified with Cellulose Nanofibrils from Ammophila arenaria for the Sensitive Detection of L-Trytophan

L-tryptophan is an essential amino acid for human health. Nanofibrillated cellulose (NFC) from marram grass (Ammophila arenaria) extracted from plants harvested in the center of Tunisia was used for the first time for the modification of a glassy carbon electrode (GCE), for the sensitive detection of L-tryptophan (Trp). After spectroscopic and morphological characterization of the extracted NFC, the GC electrode modification was monitored through cyclic voltammetry. The NFC-modified electrode exhibited good analytical performance in detecting Trp with a wide linear range between 7.5 × 10−4 mM and 10−2 mM, a detection limit of 0.2 µM, and a high sensitivity of 140.0 µA∙mM−1. Additionally, the NFC/GCE showed a good reproducibility, good selectivity versus other amino acids, uric acid, ascorbic acid, and good applicability to the detection of Trp in urine samples.

Vibrations induced by tunnel boring machine in urban areas: In situ measurements and methodology of analysis

Excavation with tunnel boring machine(TBM)can generate vibrations,causing damages to neighbouring buildings and disturbing the residents or the equipment.This problem is particularly challenging in urban areas,where TBMs are increasingly large in diameter and shallow in depth.In response to this problem,four experimental campaigns were carried out in different geotechnical contexts in France.The vibration measurements were acquired on the surface and inside the TBMs.These measurements are also complemented by few data in the literature.An original methodology of signal processing is pro-posed to characterize the amplitude of the particle velocities,as well as the frequency content of the signals to highlight the most energetic bands.The levels of vibrations are also compared with the thresholds existing in various European regulations concerning the impact on neighbouring structures and the disturbance to local residents.

Vibration-based bearing fault diagnosis of high-speed trains:A literature review

Due to the advantages of comfort and safety,high-speed trains are gradually becoming the mainstream public transport in China.Since the operating speed and mileage of high-speed trains have achieved rapid growth,it is more and more urgent to ensure their reliability and safety.As an important component in the bogies of highspeed trains,the health state of the bearing directly affects the operational safety of the trains.It is therefore necessary to diagnoze the faults of bearings in the bogies of high-speed trains as early as possible.In this paper,the bearing fault diagnostic methods for high-speed trains have been systematically summarized with their challenges and perspectives.First,it briefly introduces the structure of bearings in the bogies as well as the fault characteristic frequencies.Then,a brief review of the research on vibration-based signal processing methods and machine learning methods has been provided.Finally,the challenges and future developments of vibrationbased bearing fault diagnostic methods for high-speed trains have been analyzed.

Occurrence of D-amino acids in natural products

Since the identified standard genetic code contains 61 triplet codons of three bases for the 20 L-proteinogenic amino acids(AAs),no D-AA should be found in natural products.This is not what is observed in the living world.D-AAs are found in numerous natural compounds produced by bacteria,algae,fungi,or marine animals,and even vertebrates.A review of the literature indicated the existence of at least 132 peptide natural compounds in which D-AAs are an essential part of their structure.All compounds are listed,numbered and described herein.The two biosynthetic routes leading to the presence of D-AA in natural products are:non-ribosomal peptide synthesis(NRPS),and ribosomally synthesized and post-translationally modified peptide(RiPP)synthesis which are described.The methods used to identify the AA chirality within naturally occurring peptides are briefly discussed.The biological activity of an all-L synthetic peptide is most often completely different from that of the D-containing natural compounds.Analyzing the selected natural compounds showed that D-Ala,D-Val,D-Leu and D-Ser are the most commonly encountered D-AAs closely followed by the non-proteinogenic D-allo-Thr.D-Lys and D-Met were the least prevalent D-AAs in natu-rally occurring compounds.

A Computational Analysis of the Influence of Anastomosis Angle on Stenosis-Prone Locations during Radio-Cephalic Arteriovenous Fistula Maturation

In dialysis treatment, the radio-cephalic arteriovenous fistula (RCAVF) is a commonly used fistula, yet its low maturation rate remains a challenge. To enhance surgical outcomes, the relationship between stenosis-prone locations and RCAVF anastomosis angle is studied during maturation by developing two sets of RCAVF models for early (non-mature) and mature RCAVFs at five anastomosis angles. The impact of hemodynamics and wall shear stress (WSS) is examined to determine optimal anastomotic angles. Results indicate that acute angles produce more physiological WSS distributions and fewer disturbed regions, with early stenosis-prone regions located near the anastomosis that shift to the bending venous segment during remodeling. A pilot study comparing clinical and numerical results is conducted for validation.

有机-无机杂化核壳型乳胶粒的制备及其粒径控制

以苯乙烯乳液聚合合成种子, 再在种子外生成苯乙烯与甲基丙烯酸 3 三甲氧基硅丙酯 (MPS) 的共聚物,利用MPS中硅氧烷基的水解 缩合反应, 形成交联的壳, 得到有机 无机杂化型核壳乳胶粒. 然后用溶剂将聚苯乙烯模板溶解, 可得到空心微胶囊. 通过透射电镜 (TEM) 和动态光散射粒径仪 (DLS) 观测乳胶粒及微胶囊的形态. 并研究了乳化剂种类、介质 pH值、MPS用量和加入方式对粒径、粒子数和体系稳定性的影响. 发现非离子型乳化剂、酸性或碱性介质、MPS用量过多均促进乳胶粒子数减少, 减弱了乳液稳定性. 而采取连续滴加MPS的方法则可提高乳液的稳定性, 且粒径可控.

甲基丙烯酸3-三甲氧基硅丙酯与苯乙烯乳液共聚合机理

甲基丙烯酸3-三甲氧基硅丙酯(MPS)和苯乙烯的种子乳液聚合反应过程中同时发生自由基共聚合反应和硅氧烷基的水解缩合反应.通过对MPS在不同条件下乳液聚合过程中粒径及其分布的表征、对反应过程中MPS水解产物的跟踪2、9Si固态核磁共振谱(NMR)和红外光谱(FTIR)对反应得到的聚合产物结构的表征对反应过程和机理进行了研究.阐明了不同的反应条件(如水介质的pH值、MPS的加入量和加入方式)下,此种子乳液聚合体系中各类反应的发生场所、各场所下的反应特点、反应中间产物以及由其导致的不同的成核和聚并机理和最终聚合物的微结构.发现根据不同反应条件下的自由基共聚合速率、水解缩合速率以及MPS在粒子相和水相中分配的不同,反应过程呈现差异很大的机理,且得到的乳胶粒形态、微结构也有很大不同.

环境规划中的非线性特征

在实际环境规划中,很少考虑到非线性特征对环境投入的效益影响.以国内外目前主要3类水环境规划为例,研究了环境投入与环境改善之间的关系.对每一类环境规划,环境改善均随投入的增加而迅速减少.由于传统的环境管理或规划在选择下一种措施之前总是将大部分费用投入到前一种措施中,因此传统的环境管理或规划忽略了环境系统有关的非线性特征.应将有关费用投入以保证下一步措施获得最大的环境改善.与传统的环境管理或规划相比,这种考虑环境系统有关非线性特征影响的投入策略可以达到用较少的经费获得迅速的环境改善.

甲基丙烯酸甲酯聚合动力学和分子量模型及仿真

考虑甲基丙烯酸甲酯聚合过程中体积收缩 ,反应物和生成物的浓度变化 ,以及由于凝胶、玻璃化和笼闭等效应对各速率常数和物性参数的影响 ,从基元反应和物料平衡出发 ,推导了半间歇、有链转移剂参与情况下的聚合动力学和分子量模型 .用模型仿真计算了聚合温度、引发剂、溶剂和链转移剂的种类和浓度等对甲基丙烯酸甲酯聚合动力学和聚合过程中分子量变化的影响规律 ,并与实验和文献数据进行比较 .

第十九届国际干燥会议(IDS2014)介绍

1988年,法国凡尔赛成功举办了令人难忘的第6届国际干燥会议(IDS)。26年后,法国第二次在里昂国际会议中心于2014年8月24-27日荣幸并圆满的举办了第19届国际干燥会议。里昂是罗纳—阿尔卑斯地区的行政首府,是法国的第二大经济区和法国最大的学术研究中心。

Molecular mechanisms of mesenchymal stem cell differentiation towards osteoblasts

Bone is a dynamic tissue that is constantly renewed by the coordinated action of two cell types, i.e., the bone-resorbing osteoclasts and the bone-forming osteoblasts. However, in some circumstances, bone regeneration exceeds bone self repair capacities. This is notably often the case after bone fractures, osteolytic bone tumor surgery, or osteonecrosis. In this regard,bone tissue engineering with autologous or allogenic mesenchymal stem cells(MSCs) is been widely developed. MSCs can be isolated from bone marrow or other tissues such as adipose tissue or umbilical cord, and can be implanted in bone defects with or without prior amplification and stimulation. However, the outcome of most pre-clinical studies remains relatively disappointing. A better understanding of the successive steps and molecular mechanisms involved in MSC-osteoblastic differentiation appears to be crucial to optimize MSC-bone therapy. In this review, we first present the important growth factors that stimulate osteoblastogenesis. Then we review the main transcription factors that modulate osteoblast differentiation, and the microRNAs(miRs)that inhibit their expression. Finally, we also discuss articles dealing with the use of these factors and miRs in the development of new bone MSC therapy strategies. We particularly focus on the studies using human MSCs, since significant differences exist between osteoblast differentiation mechanisms in humans and mice for instance.

(La0.8A0.2)MnO3(A=Sr,K) perovskite catalysts for NO and C10H22 oxidation and selective reduction of NO by C(10)H(22)

In this work, we studied the catalytic activity of LaMnO3 and(La0.8A0.2)MnO3(A = Sr, K) perovskite catalysts for oxidation of NO and C10H22 and selective reduction of NO by C10H22. The catalytic per‐formances of these perovskites were compared with that of a 2 wt% Pt/SiO2 catalyst. The La site substitution increased the catalytic properties for NO or C10H22 oxidation compared with the non‐substituted LaMnO3 sample. For the most efficient perovskite catalyst,(La0.8Sr0.2)MnO3, the results showed the presence of two temperature domains for NO adsorption:(1) a domain corre‐sponding to weakly adsorbed NO, desorbing at temperatures lower than 270 °C and(2) a second domain corresponding to NO adsorbed on the surface as nitrate species, desorbing at temperatures higher than 330 °C. For the Sr‐substituted perovskite, the maximum NO2 yield of 80% was observed in the intermediate temperature domain (around 285 °C). In the reactant mixture of NO/C10H22/O2/H2O/He,(La0.8Sr0.2)MnO3 perovskite showed better performance than the 2 wt% Pt/SiO2 catalyst: NO2 yields reaching 50% and 36% at 290 and 370 °C, respectively. This activity improvement was found to be because of atomic scale interactions between the A and B active sites, Sr2+ cation and Mn4+/Mn3+ redox couple. Thus,(La0.8Sr0.2)MnO3 perovskite could be an alternative free noble metal catalyst for exhaust gas after treatment.

Cytomegalovirus and ulcerative colitis:Place of antiviraltherapy

The link between cytomegalovirus(CMV) infection and inflammatory bowel diseases remains an important subject of debate. CMV infection is frequent in ulcerative colitis(UC) and has been shown to be potentially harmful. CMV reactivation needs to be diagnosed using methods that include in situ detection of viral markers by immunohistochemistry or by nucleic acid amplification techniques. Determination of the density of infection using quantitative tools(numbers of infected cells or copies of the genome) is particularly important. Although CMV reactivation can be considered as an innocent bystander in active flareups of refractory UC, an increasing number of studies suggest a deleterious role of CMV in this situation. The presence of colonic CMV infection is possibly linked to a decreased response to steroids and other immunosuppressive agents. Some treatments, notably steroids and cyclosporine A, have been shown to favor CMV reactivation, which seems not to be the case for therapies using anti-tumor necrosis factor drugs. According to these findings, in flare-ups of refractory UC, it is now recommended to look for the presence of CMV reactivation by using quantitative tools in colonic biopsies and to treat them with ganciclovir in cases of high viral load or severe disease.

Biosorption of cadmium(II) and lead(II) ions from aqueous solutions onto dried activated sludge

The removal of heavy-metal ions from aqueous solutions by using dried activated sludge has been investigated in batch systems. Effect of solution pH, initial metal ion concentration, and temperature were determined. The results of the kinetic studies showed that the uptake processes of the two metal ions（Cd（Ⅱ） and Pb（Ⅱ）） followed the pseudo-second-order rate expression. The equilibrium data fitted very well to both the Langmuir and Freundlich adsorption models. The FT-IR analysis showed that the main mechanism of Cd（Ⅱ） and Pb（Ⅱ） biosorption onto dried activated sludge was their binding with amide I group.

Is transfusion-transmitted dengue fever a potential public health threat?

Dengue is an arboviruses due to single-stranded enveloped ribonucleic acid viruses, named dengue viruses(DENV), that include four serotypes and are mainly transmitted via the bite of mosquitoes of the genus Aedes(A. aegypti and A. albopictus). The distribution of the disease was historically limited to intertropical areas; however, during the last thirty years, the perimeter of the disease extended considerably and temperate areas are now at risk of outbreaks. The present global burden of dengue is considerable: 2.5 billion people over more than 100 countries are concerned; 50 to 100 million infections occur every year, with a number of fatal cases of approximately 20000. Although frequently asymptomatic or limited to a mild fever, dengue is responsible for severe cases mainly consecutive to the occurrence of hemorrhagic complications that can lead to shock and death, notably in children from poorresource settings. The place of DENV as a transfusiontransmitted pathogen has been recognized only in 2008. At the present time, only five cases of transfusiontransmitted dengue, including one case of dengue hemorrhagic fever, have been formerly documented. This review provides a general overview of dengue, its viruses and their vectors. It replaces the disease in the context of other viral diseases transmitted by arthropods. It discusses the threat of dengue on the supply of blood products in endemic and non endemic areas. Finally, it describes the specific and non specific measures available for improving the security of blood products with regards to this emerging risk. Interestingly, in 2009, the American Association of Blood Banks placed DENV in the highest category of emerging infectious agents for their potential impact on transfusion recipient safety for the next years in North America.

Predictors of Clostridium difficile infection severity in patients hospitalised in medical intensive care

AIM:To describe and analyse factors associated with Clostridium difficile infection(CDI)severity in hospitalised medical intensive care unit patients.METHODS:We performed a retrospective cohort study of 40 patients with CDI in a medical intensive care unit(MICU)at a French university hospital.We include patients hospitalised between January 1,2007and December 31,2011.Data on demographics characteristics,past medical history,CDI description was collected.Exposure to risk factors associated with CDI within 8 wk before CDI was recorded,including previous hospitalisation,nursing home residency,antibiotics,antisecretory drugs,and surgical procedures.RESULTS:All included cases had their first episode of CDI.The mean incidence rate was 12.94 cases/1000admitted patients,and 14.93,8.52,13.24,19.70,and8.31 respectively per 1000 admitted patients annually from 2007 to 2011.Median age was 62.9[interquartile range(IQR)55.4-72.40]years,and 13(32.5%)were women.Median length of MICU stay was 14.0d(IQR 5.0-22.8).In addition to diarrhoea,the clinical symptoms of CDI were fever(>38℃)in 23 patients,abdominal pain in 15 patients,and ileus in 1 patient.The duration of diarrhoea was 13.0(8.0-19.5)d.In addition to diarrhoea,the clinical symptoms of CDI were fever(>38℃)in 23 patients,abdominal pain in 15 patients,and ileus in 1 patient.Prior to CDI,38patients(95.0%)were exposed to antibiotics,and 12(30%)received at least 4 antibiotics.Fluoroquinolones,3rdgeneration cephalosporins,coamoxiclav and tazocillin were prescribed most frequently(65%,55%,40%and 37.5%,respectively).The majority of cases were hospital-acquired(n=36,90%),with 5 cases(13.9%)being MICU-acquired.Fifteen patients had severe CDI.The crude mortality rate within 30 d after diagnosis was 40%(n=16),with 9 deaths(9 over 16;56.3%)related to CDI.Of our 40 patients,15(37.5%)had severe CDI.Multivariate logistic regression showed that male gender[odds ratio(OR):8.45;95%CI:1.06-67.16,P=0.044],rising serum C-reactive protein levels(OR=1.11;95%CI:1.02-1.21,P=0.021),and previous exposure to fluoroquinolones(OR=9.29;95%CI:1.16-74.284,P=0.036)were independently associated with severe CDI.CONCLUSION:We report predictors of severe CDI not dependent on time of assessment.Such factors could help in the development of a quantitative score in ICU’s patients.

基于格子波尔兹曼的机器人视觉特征点检测

针对Harris特征点检测算法中图像存在角点信息丢失的问题,提出基于格子波尔兹曼结合Harris算法的机器人视觉特征点检测方法。格子波尔兹曼具有并行操作的优点,可以保证机器人导航的实时性。通过格子波尔兹曼方法对图像进行预处理,然后使用Harris算法,实现特征点的有效检测。实验结果表明,该方法更加准确地选择特征点,减少特征点数目的同时,提升了特征点的质量,完成了特征相对不明显的点的检测。

XEN gel stent: a total delayed-onset postoperative hyphema

Dear Editor,Minimally invasive glaucoma surgery (MIGS) is a lessinvasive surgical alternative to filtering surgery for reducing intraocular pressure (IOP). This technique has been shown to offer long-term outcomes equivalent to filtering surgery[1]. The XEN gel implant (Allergan Inc., CA, USA) is one of MIGS procedures. This implant consists of a 6-mm tube of collagen-derived gelatin cross-linked with glutaraldehyde, preloaded in an injector.

Physico-Chemical and Thermal Characterization of Some Lignocellulosic Fibres: <i>Ananas comosus</i>(AC), <i>Neuropeltis acuminatas</i>(NA) and <i>Rhecktophyllum camerunense</i>(RC)

This paper focuses on the study of the physical, biochemical, structural, and thermal properties of plant fibres of Rhecktophyllum camerunense (RC), Neuropeltis acuminatas (NA) and Ananas comosus (AC) from the equatorial region of Cameroon. The traditional use of these fibres inspired researchers to investigated their properties. This study aims at improving the state of knowledge with a view to diversifying applications. The fibres are extracted by retting. Then, their apparent density was measured following the ASTM D792 standard and their water moisture absorption and moisture content were also evaluated. Their molecular structure was studied by ATR-FTIR spectroscopy. A quantitative analysis of the biochemical composition was performed according to the analytical technique for the pulp and paper industry (TAPPI). A TGA/DSC analysis was also performed. The results reveal that the AC, NA and RC fibres have densities of 1.26 ± 1.06, 0.846 ± 0.13 and 0.757 ± 0.08 g·cm-3 respectively. They are also hydrophilic with a water absorption rate of 188.64 ± 11.94%, 276.16% ± 8.07% and 198.17% ± 20%. They have a moisture content of 12.21%, 10.36% and 9.37%. The studied fibres exhibit functional groups that are related to the presence of hemicellulose, pectin, lignin and cellulose. The cellulose crystallinity index was found to be 67.99%, 46.5% and 59.72% respectively. The fibres under study have the following chemical composition: an extractive content of 3.07%, 14.77% and 8.74%;a pectin content of 4.15%, 7.69% and 3.45%;a hemicellulose content of 4.90%, 15.33% and 7.42%;a cellulose content of 68.11%, 36.08% and 65.15%;a lignin content of 12.01%, 25.15% and 16.2%;and an ash content of 0.27%, 1.53% and 0.47% respectively. The thermal transitions observed on the thermograms correlate with the TAPPI chemical composition. It is observed that these fibres are thermally stable up to temperatures of 200°C, 220°C and 285°C. These results make it possible to envisage uses similar to those of sisal, hemp and flax fibres.

糖脂结构对变色囊泡检测大肠杆菌的影响

研究了3种不同结构的糖分子(双十八烷基甘油基-β-葡萄糖苷(DGG)、1,2-O-双十八烷基-3-O-β-D-麦芽三糖基-甘油醇(DMTG)、3,6,9,12-四氧杂-10-胆甾基-2-乙酰胺-2-脱氧-β-D-吡喃葡萄苷(DL3))对大肠杆菌(E.coli)识别能力的影响。利用比色法测定囊泡对Z.coli的识别能力,实验结果表明:检测E.coli 3种体系的灵敏度大小顺序为DL3/TCDA>DMTG/TCDA>DGG/TCDA;具有多糖结构和水溶性的一(CH_2CH_2O)_3—结构的糖脂会有利于检测。红外光谱的研究证明了糖脂分子插入了聚联乙炔结构。