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 T...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.展开更多
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-pron...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.展开更多
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...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.展开更多
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...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.展开更多
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 thes...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.展开更多
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....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.展开更多
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. T...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.展开更多
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. a...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.展开更多
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 wi...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.展开更多
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 equ...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.展开更多
This paper focuses on the study of the physical, biochemical, structural, and thermal properties of plant fibres of <i>Rhecktophyllum camerunense</i> (RC), <i>Neuropeltis acuminatas</i> (NA) an...This paper focuses on the study of the physical, biochemical, structural, and thermal properties of plant fibres of <i>Rhecktophyllum camerunense</i> (RC), <i>Neuropeltis acuminatas</i> (NA) and <i>Ananas</i> <i>comosus</i> (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<sup>-3</sup> 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.展开更多
The intrinsic physical properties of the noble metal nanoparticles,which are highly sensitive to the nature of their local molecular environment,make such systems ideal for the detection of molecular recognition event...The intrinsic physical properties of the noble metal nanoparticles,which are highly sensitive to the nature of their local molecular environment,make such systems ideal for the detection of molecular recognition events.The current review describes the state of the art concerning molecular recognition of Noble metal nanoparticles.In the first part the preparation of such nanoparticles is discussed along with methods of capping and stabilization.A brief discussion of the three common methods of functionalization:Electrostatic adsorption;Chemisorption;Affinity-based coordination is given.In the second section a discussion of the optical and electrical properties of nanoparticles is given to aid the reader in understanding the use of such properties in molecular recognition.In the main section the various types of capping agents for molecular recognition;nucleic acid coatings,protein coatings and molecules from the family of supramolecular chemistry are described along with their numerous applications.Emphasis for the nucleic acids is on complementary oligonucleotide and aptamer recognition.For the proteins the recognition properties of antibodies form the core of the section.With respect to the supramolecular systems the cyclodextrins,calix[n]arenes,dendrimers,crown ethers and the cucurbitales are treated in depth.Finally a short section deals with the possible toxicity of the nanoparticles,a concern in public health.展开更多
The absorption responses of blank silicon and black silicon(silicon with micro/nano-conical surface structures) wafers to an 808-nm continuous-wave(CW) laser are investigated at room temperature by terahertz time-...The absorption responses of blank silicon and black silicon(silicon with micro/nano-conical surface structures) wafers to an 808-nm continuous-wave(CW) laser are investigated at room temperature by terahertz time-domain spectroscopy. The transmission of the blank silicon shows an appreciable change, from ground state to the pump state, with amplitude varying up to 50%, while that of the black silicon(BS) with different cone sizes is observed to be more stable. Furthermore,the terahertz transmission through BS is observed to be strongly dependent on the size of the conical structure geometry.The conductivities of blank silicon and BS are extracted from the experimental data with and without pumping. The non-photo-excited conductivities increase with increasing frequency and agree well with the Lorentz model, whereas the photo-excited conductivities decrease with increasing frequency and fit well with the Drude–Smith model. Indeed, for BS, the conductivity, electron density and mobility are found to correlate closely with the size of the conical structure.This is attributed to the influence of space confinement on the carrier excitation, that is, the carriers excited at the BS conical structure surface have a stronger localization effect with a backscattering behavior in small-sized microstructures and a higher recombination rate due to increased electron interaction and collision with electrons, interfaces and grain boundaries.展开更多
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China(52375078).
文摘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.
文摘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.
基金Financial supports by national agency for research are gratefully acknowledged.
文摘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.
文摘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.
基金The National New Century Scholarship (No. NCET-05-0387) the France-China P2R Programs and the Specialized Research Fundfor the Doctoral Program of Higher Education (No. 20050247016)
文摘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.
文摘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.
基金Supported by A grant for her PhD from Sanofi Pasteur,France,to Khanafer N
文摘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.
文摘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.
文摘This paper focuses on the study of the physical, biochemical, structural, and thermal properties of plant fibres of <i>Rhecktophyllum camerunense</i> (RC), <i>Neuropeltis acuminatas</i> (NA) and <i>Ananas</i> <i>comosus</i> (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<sup>-3</sup> 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.
文摘The intrinsic physical properties of the noble metal nanoparticles,which are highly sensitive to the nature of their local molecular environment,make such systems ideal for the detection of molecular recognition events.The current review describes the state of the art concerning molecular recognition of Noble metal nanoparticles.In the first part the preparation of such nanoparticles is discussed along with methods of capping and stabilization.A brief discussion of the three common methods of functionalization:Electrostatic adsorption;Chemisorption;Affinity-based coordination is given.In the second section a discussion of the optical and electrical properties of nanoparticles is given to aid the reader in understanding the use of such properties in molecular recognition.In the main section the various types of capping agents for molecular recognition;nucleic acid coatings,protein coatings and molecules from the family of supramolecular chemistry are described along with their numerous applications.Emphasis for the nucleic acids is on complementary oligonucleotide and aptamer recognition.For the proteins the recognition properties of antibodies form the core of the section.With respect to the supramolecular systems the cyclodextrins,calix[n]arenes,dendrimers,crown ethers and the cucurbitales are treated in depth.Finally a short section deals with the possible toxicity of the nanoparticles,a concern in public health.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574408,11504439,61627814,and 61675238)the National Key Research and Development Program of China(Grant No.2017YFB0405402)+1 种基金the National Instrumentation Program of China(Grant No.2012YQ14000508)the Young-talent Plan of State Affairs Commission,China(Grant No.2016-3-02)
文摘The absorption responses of blank silicon and black silicon(silicon with micro/nano-conical surface structures) wafers to an 808-nm continuous-wave(CW) laser are investigated at room temperature by terahertz time-domain spectroscopy. The transmission of the blank silicon shows an appreciable change, from ground state to the pump state, with amplitude varying up to 50%, while that of the black silicon(BS) with different cone sizes is observed to be more stable. Furthermore,the terahertz transmission through BS is observed to be strongly dependent on the size of the conical structure geometry.The conductivities of blank silicon and BS are extracted from the experimental data with and without pumping. The non-photo-excited conductivities increase with increasing frequency and agree well with the Lorentz model, whereas the photo-excited conductivities decrease with increasing frequency and fit well with the Drude–Smith model. Indeed, for BS, the conductivity, electron density and mobility are found to correlate closely with the size of the conical structure.This is attributed to the influence of space confinement on the carrier excitation, that is, the carriers excited at the BS conical structure surface have a stronger localization effect with a backscattering behavior in small-sized microstructures and a higher recombination rate due to increased electron interaction and collision with electrons, interfaces and grain boundaries.