The severe drought observed in the Sahel during 1970s, 1980s and 1990s has deeply affected the population as well as the economies and the eco-systems of this climatic area. The GGW Initiative spearheaded by Africa Un...The severe drought observed in the Sahel during 1970s, 1980s and 1990s has deeply affected the population as well as the economies and the eco-systems of this climatic area. The GGW Initiative spearheaded by Africa Union in 2007 proposed to combat the land degradation and desertification by planting a wall of trees stretching from Dakar to Djibouti. A reforestation was then conducted in the Senegal’s GGW since 2006 as part as other areas in the Sahel. This paper aims to evaluate the carbon sequestration dynamics in the sites of the Senegal’s GGW over the last three decades. The method consists firstly of analyzing the evolution of land cover and land use dynamics based on ESA-CCI LC satellite data. There is an improvement of the surface areas of tree and shrub savanna of 11.40% (Tessekere), 8.25% (Syer) and 2.70% (Loughere-Thioly). The regreening of the different localities and a positive dynamic observed is explained by the return to normal rainfall and to reforestation actions, agroforestry practices, better management of natural resources undertaken. However, some non-reforested sites showed an opposite trend despite of the normal rainfall. Secondly, the results on land mapping are used as a proxy for the assessment of carbon stocks. The dynamic observed in vegetation cover since the beginning of the reforestation made it possible to sequester 5.8 million tons of carbon representing respectively 2.31% of African GGW. This gain in stored carbon is equivalent to 21.2 million tons of CO<sub>2</sub> captured in the atmosphere. Through this study, it appears that carbon storage becomes significant 8 to 10 years after the start of reforestation. An urbanization without respect for the environmental factors could be a danger for the climate (case of Ballou).展开更多
Corona virus infection and the risk of contagiousness to medical personnel or patients during endoscopy necessitated further measures in the endoscopy rooms. The objective of this study was to assess the experience of...Corona virus infection and the risk of contagiousness to medical personnel or patients during endoscopy necessitated further measures in the endoscopy rooms. The objective of this study was to assess the experience of patients in endoscopy rooms during the COVID-19 epidemic in West Africa. Patients and Methods: This was a multicenter cross-sectional study that took place over a period of 3 months (June to August 2020) in endoscopy centers in Burkina Faso, Benin and Niger. An online questionnaire was sent to patients who had performed upper digestive endoscopies, in 8 digestive endoscopy centers including private, public and religious structures. Depending on the choice of patients, questionnaires were either sent electronically or completed in the endoscopy room with the help of field investigators. The choice of centers was random from the list of centers and descriptive analyses were carried out. Results: A total of 294 patients responded to the online questionnaire. There were 37 lower and 257 upper gastrointestinal endoscopies. The female sex represented 52.1%. The wait times for obtaining an endoscopy appointment were considered satisfactory by 281 patients 95.6%. In the endoscopy departments, 112 patients, or 38.1%, were questioned about the risk factors for contamination of SARS-CoV-2. Among the risk factors found, 6 patients (2.0%) would have traveled abroad in the 2 weeks preceding the examination, 4 patients 1.4% had already been in contact with a subject at risk. The most frequent symptoms were chest pain (80 cases;27.2%), flu-like syndrome (29 cases;9.9%), cough (40 cases;13.6%), fever (46 cases;15.6%). In contrast, ageusia (7 cases;2.4%) and anosmia (5 cases;1.7%) were only found in very few patients. Twenty-two patients (7.5%) felt highly exposed to COVID-19 during the endoscopy examination and 144 patients (48.9%) rated the examination as satisfactory. Conclusion: Gastrointestinal symptoms initially described as rare are being reported with increasing frequency in studies and may motivate the request for endoscopy examinations. However, the risk associated with infection with SARS-CoV-2 does not seem to have been sufficiently taken into account in endoscopy centers in the 3 countries.展开更多
Background:The use of industrial by-products rich in bioactive compounds as animal feeds can reduce greenhouse gas production.Paulownia leaves silage(PLS)was supplemented to dairy cows'diet and evaluated in vitro(...Background:The use of industrial by-products rich in bioactive compounds as animal feeds can reduce greenhouse gas production.Paulownia leaves silage(PLS)was supplemented to dairy cows'diet and evaluated in vitro(Exp.1;Rusitec)and in vivo(Exp.2,cannulated lactating dairy cows and Exp.3,non-cannulated lactating dairy cows).The study investigated the PLS effect on ruminal fermentation,microbial populations,methane production and concentration,dry matter intake(DMI),and fatty acid(FA)proportions in ruminal fluid and milk.Results:Several variables of the ruminal fluid were changed in response to the inclusion of PLS.In Exp.1,the p H increased linearly and quadratically,whereas ammonia and total volatile fatty acid(VFA)concentrations increased linearly and cubically.A linear,quadratic,and cubical decrease in methane concentration was observed with increasing dose of the PLS.Exp.2 revealed an increase in ruminal p H and ammonia concentrations,but no changes in total VFA concentration.Inclusion of PLS increased ruminal propionate(at 3 h and 6 h after feeding),isovalerate,and valerate concentrations.Addition of PLS also affected several populations of the analyzed microorganisms.The abundances of protozoa and bacteria were increased,whereas the abundance of archaea were decreased by PLS.Methane production decreased by 11%and 14%in PLS-fed cows compared to the control in Exp.2 and 3,respectively.Exp.3 revealed a reduction in the milk protein and lactose yield in the PLS-fed cows,but no effect on DMI and energy corrected milk yield.Also,the PLS diet affected the ruminal biohydrogenation process with an increased proportions of C18:3 cis-9 cis-12 cis-15,conjugated linoleic acid,C18:1 trans-11 FA,polyunsaturated fatty acids(PUFA),and reduced n6/n3 ratio and saturated fatty acids(SFA)proportion in milk.The relative transcript abundances of the 5 of 6 analyzed genes regulating FA metabolism increased.Conclusions:The dietary PLS replacing the alfalfa silage at 60 g/kg diet can reduce the methane emission and improve milk quality with greater proportions of PUFA,including conjugated linoleic acid,and C18:1 trans-11 along with reduction of SFA.展开更多
BACKGROUND Israel has a high rate of Jewish immigration and a high prevalence of inflammatory bowel disease(IBD).AIM To compare IBD prevalence in first-generation immigrants vs Israel-born Jews.METHODS Patients with a...BACKGROUND Israel has a high rate of Jewish immigration and a high prevalence of inflammatory bowel disease(IBD).AIM To compare IBD prevalence in first-generation immigrants vs Israel-born Jews.METHODS Patients with a diagnosis of IBD as of June 2020 were included from the validated epi-IIRN(Israeli IBD Research Nucleus)cohort that includes 98%of the Israeli population.We stratified the immigration cohort by IBD risk according to country of origin,time period of immigration,and age group as of June 2020.RESULTS A total of 33544 patients were ascertained,of whom 18524(55%)had Crohn’s disease(CD)and 15020(45%)had ulcerative colitis(UC);28394(85%)were Israel-born and 5150(15%)were immigrants.UC was more prevalent in immigrants(2717;53%)than in non-immigrants(12303,43%,P<0.001),especially in the<1990 immigration period.After adjusting for age,longer duration in Israel was associated with a higher point prevalence rate in June 2020(high-risk origin:Immigration<1990:645.9/100000,≥1990:613.2/100000,P=0.043;intermediate/low-risk origin:<1990:540.5/100000,≥1990:192.0/100000,P<0.001).The prevalence was higher in patients immigrating from countries with high risk for IBD(561.4/100000)than those originating from intermediate-/low-risk countries(514.3/100000;P<0.001);non-immigrant prevalence was 528.9/100000.CONCLUSION Lending support to the environmental effect on IBD etiology,we found that among immigrants to Israel,the prevalence of IBD increased with longer time since immigration,and was related to the risk of IBD in the country of origin.The UC rate was higher than that of CD only in those immigrating in earlier time periods.展开更多
A class of nonlinear nonlocal for singularly perturbed Robin initial boundary value problems for reaction diffusion equations is considered. Under suitable conditions, firstly, the outer solution of the original probl...A class of nonlinear nonlocal for singularly perturbed Robin initial boundary value problems for reaction diffusion equations is considered. Under suitable conditions, firstly, the outer solution of the original problem is obtained, secondly, using the stretched variable, the composing expansion method and the expanding theory of power series the initial layer is constructed, finally, using the theory of differential inequalities the asymptotic behavior of solution for the initial boundary value problems are studied and educing some relational inequalities the existence and uniqueness of solution for the original problem and the uniformly valid asymptotic estimation is discussed.展开更多
Chronic hepatitis B(CHB)is a global health issue that increases the risk of liver cirrhosis and hepatocellular carcinoma in infected patients.Metabolic syndrome(Met S)is a disease endemic mostly to the developed count...Chronic hepatitis B(CHB)is a global health issue that increases the risk of liver cirrhosis and hepatocellular carcinoma in infected patients.Metabolic syndrome(Met S)is a disease endemic mostly to the developed countries.It is associated with high cardiovascular mortality and morbidity,diabetes mellitus as well as cancer.In this manuscript,we systematically review the published data on the relationship between Met S and CHB infection.Multiple studies have described highly variable correlations between CHB on one hand and Met S,non-alcoholic fatty liver disease and dyslipidemia on the other.No association between CHB and diabetes mellitus or atherosclerosis has been described as of now.The presence of Met S in patients infected with hepatitis B virus increases the risk of fibrosis,cirrhosis and hepatocellular carcinoma.Appropriate lifestyle,but also pharmacological interventions are needed to prevent the development of these complications.展开更多
Nowadays, the material recycling is a growing trend in development of building materials and therefore using of secondary raw materials for production new building materials is in accordance with sustainable developme...Nowadays, the material recycling is a growing trend in development of building materials and therefore using of secondary raw materials for production new building materials is in accordance with sustainable development in civil engineering. Therefore, it is increasingly becoming crucial to accelerate the transition from application of non-renewable sources of raw materials to renewable raw materials. One fast renewable resource is natural plant fibers. The use of the cellulosic fibers as environmentally friendly material in building products contributes to the environmental protection and saves non-renewable resources of raw materials. Wood fibers and recycled cellulose fibers of waste paper appear as suited reinforcing elements for cement-based materials. In this paper, there is used application of Fourier transform infrared spectroscopy (FTIR) on cellulose fibers coming from different sources. FTIR spectra of cellulose fiber samples are investigated and compared with reference sample of cellulose.展开更多
Doping effects of manganese (Mn) on catalytic performance and structure evolution of NiMgO catalysts for synthesis of multi-walled carbon nanotubes (MWCNTs) from methane were investigated for the first time. Addit...Doping effects of manganese (Mn) on catalytic performance and structure evolution of NiMgO catalysts for synthesis of multi-walled carbon nanotubes (MWCNTs) from methane were investigated for the first time. Addition of Mn in NiMgO catalyst can greatly improve the MWCNTs yield. Mno.2NiMgO catalyst among the tested ones gives the highest MWCNTs yield as 2244%, which is two times higher than that of the catalyst without Mn. The structure evolution, reduction behaviors and surface chemical properties of MnNiMgO catalysts with various Mn contents were studied in detail. It was found that the stable solid solution of NiMgO2 formed in NiMgO catalyst was disturbed by the addition of Mn. Instead, another solid solution of MnMg608 is formed. More amount of Ni can be reduced and dispersed on the catalyst surface to be acted as active sites. Importantly, the changes of Ni content on the surface are correlated with the Ni particle size and the outer diameter of MWCNTs, suggesting the controllable synthesis of MWCNTs over MnNiMgO catalysts.展开更多
Ionizing radiation caused by medical treatments,nuclear events or even space flights can irreversibly damage structure and function of brain cells.That can result in serious brain damage,with memory and behavior disor...Ionizing radiation caused by medical treatments,nuclear events or even space flights can irreversibly damage structure and function of brain cells.That can result in serious brain damage,with memory and behavior disorders,or even fatal oncologic or neurodegenerative illnesses.Currently used treatments and drugs are mostly targeting biochemical processes of cell apoptosis,radiation toxicity,neuroinflammation,and conditions such as cognitive-behavioral disturbances or others that result from the radiation insult.With most drugs,the side effects and potential toxicity are also to be considered.Therefore,many agents have not been approved for clinical use yet.In this review,we focus on the latest and most effective agents that have been used in animal and also in the human research,and clinical treatments.They could have the potential therapeutical use in cases of radiation damage of central nervous system,and also in prevention considering their radioprotecting effect of nervous tissue.展开更多
Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers.This is done in order to provide for fast transportation through the North Sea Route and safe ...Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers.This is done in order to provide for fast transportation through the North Sea Route and safe operation in extreme ice conditions.Currently,new large size gas and oil carriers and container ships are being designed and built with beams much greater than the beams of existing icebreakers.At the same time,no mathematical description exists for the breaking mechanism of ice channel edges,when such vessels move under icebreaker escort.This paper suggests a simple method for assessment of the ice resistance in the case of a large ship running in an icebreaker channel;the method is based on modification of well-known semi-empirical methods for calculation of the ice resistance to ships in level and broken ice.The main feature of the proposed calculation scheme consists in that different methods are applied to estimate the ice resistance in broken ice and due to breaking of level ice edges.The combination of these methods gives a deliverable ice resistance of a large size vessel moving under icebreaker assistance in a newly made ice channel.In general,proposed method allows to define the speed of a carrier moving in an ice channel behind a modern linear icebreaker and could be applied at the ship design stage and during development of the marine transportation system.The paper also discusses the ways for further refinement of the assessment procedure suggested.展开更多
The ocean current response to a hurricane on the shelf-break is examined. The study area is the DeSoto Canyon in the northeast Gulf of Mexico, and the event is the passage of 1998 Hurricane Georges with a maximum wind...The ocean current response to a hurricane on the shelf-break is examined. The study area is the DeSoto Canyon in the northeast Gulf of Mexico, and the event is the passage of 1998 Hurricane Georges with a maximum wind speed of 49 m/s. The data sets used for analysis consist of the mooring data taken by the Field Program of the DeSoto Canyon Eddy Intrusion Study, and simultaneous winds observed by NOAA (National Oceanic and Atmospheric Administration) Moored Buoy 42040. Time-depth ocean current energy density images derived from the observed data show that the ocean currents respond almost immediately to the hurricane with important differences on and offthe shelf. On the shelf, in the shallow water of 100 m, the disturbance penetrates rapidly downward to the bottom and forms two energy peaks, the major peak is located in the mixed layer and the secondary one in the lower layer. The response dissipates quickly after external forcing disappears. Offthe shelf, in the deep water, the major disturbance energy seems to be trapped in the mixed layer with a trailing oscillation; although the disturbance signals may still be observed at the depths of 500 and 1 290 m. Vertical dispersion analysis reveals that the near-initial wave packet generated offthe shelf consists of two modes. One is a barotropic wave mode characterized by a fast decay rate of velocity amplitude of 0.020 s^-, and the other is baroclinic wave mode characterized by a slow decay rate of 0.006 9 s^-1. The band-pass-filtering and empirical function techniques are employed to the frequency analysis. The results indicate that ialf frequencies shift above the local inertial frequency. On the shelf, the average frequency is 1.04fin the mixed layer, close to the diagnosed frequency of the first baroclinic mode, and the average frequency increases to 1.07fin the thermocline. Offthe shelf, all frequencies are a little smaller than the diagnosed frequency of the first mode. The average frequency decreases from 1.035fin the mixed layer to 1.02fin the thermocline, implying a trend for the shift in frequency of the oscillations towards f with the depth.展开更多
Possible influences of the Barents Sea ice anomalies on the Eurasian atmospheric circulation and the East China precipitation distribution in the late spring and early summer (May-June) are investigated by analyzing t...Possible influences of the Barents Sea ice anomalies on the Eurasian atmospheric circulation and the East China precipitation distribution in the late spring and early summer (May-June) are investigated by analyzing the observational data and the output of an atmospheric general circulation model (AGCM). The study indicates that the sea ice condition of the Barents Sea from May to July may be interrelated with the atmospheric circulation of June. When there is more than average sea ice in the Barents Sea, the local geopotential height of the 500-hPa level will decrease, and the same height in the Lake Baikal and Okhotsk regions will increase and decrease respectively to form a wave-chain structure over North Eurasia. This kind of anomalous height pattern is beneficial to more precipitation in the south part of East China and less in the north.展开更多
文摘The severe drought observed in the Sahel during 1970s, 1980s and 1990s has deeply affected the population as well as the economies and the eco-systems of this climatic area. The GGW Initiative spearheaded by Africa Union in 2007 proposed to combat the land degradation and desertification by planting a wall of trees stretching from Dakar to Djibouti. A reforestation was then conducted in the Senegal’s GGW since 2006 as part as other areas in the Sahel. This paper aims to evaluate the carbon sequestration dynamics in the sites of the Senegal’s GGW over the last three decades. The method consists firstly of analyzing the evolution of land cover and land use dynamics based on ESA-CCI LC satellite data. There is an improvement of the surface areas of tree and shrub savanna of 11.40% (Tessekere), 8.25% (Syer) and 2.70% (Loughere-Thioly). The regreening of the different localities and a positive dynamic observed is explained by the return to normal rainfall and to reforestation actions, agroforestry practices, better management of natural resources undertaken. However, some non-reforested sites showed an opposite trend despite of the normal rainfall. Secondly, the results on land mapping are used as a proxy for the assessment of carbon stocks. The dynamic observed in vegetation cover since the beginning of the reforestation made it possible to sequester 5.8 million tons of carbon representing respectively 2.31% of African GGW. This gain in stored carbon is equivalent to 21.2 million tons of CO<sub>2</sub> captured in the atmosphere. Through this study, it appears that carbon storage becomes significant 8 to 10 years after the start of reforestation. An urbanization without respect for the environmental factors could be a danger for the climate (case of Ballou).
文摘Corona virus infection and the risk of contagiousness to medical personnel or patients during endoscopy necessitated further measures in the endoscopy rooms. The objective of this study was to assess the experience of patients in endoscopy rooms during the COVID-19 epidemic in West Africa. Patients and Methods: This was a multicenter cross-sectional study that took place over a period of 3 months (June to August 2020) in endoscopy centers in Burkina Faso, Benin and Niger. An online questionnaire was sent to patients who had performed upper digestive endoscopies, in 8 digestive endoscopy centers including private, public and religious structures. Depending on the choice of patients, questionnaires were either sent electronically or completed in the endoscopy room with the help of field investigators. The choice of centers was random from the list of centers and descriptive analyses were carried out. Results: A total of 294 patients responded to the online questionnaire. There were 37 lower and 257 upper gastrointestinal endoscopies. The female sex represented 52.1%. The wait times for obtaining an endoscopy appointment were considered satisfactory by 281 patients 95.6%. In the endoscopy departments, 112 patients, or 38.1%, were questioned about the risk factors for contamination of SARS-CoV-2. Among the risk factors found, 6 patients (2.0%) would have traveled abroad in the 2 weeks preceding the examination, 4 patients 1.4% had already been in contact with a subject at risk. The most frequent symptoms were chest pain (80 cases;27.2%), flu-like syndrome (29 cases;9.9%), cough (40 cases;13.6%), fever (46 cases;15.6%). In contrast, ageusia (7 cases;2.4%) and anosmia (5 cases;1.7%) were only found in very few patients. Twenty-two patients (7.5%) felt highly exposed to COVID-19 during the endoscopy examination and 144 patients (48.9%) rated the examination as satisfactory. Conclusion: Gastrointestinal symptoms initially described as rare are being reported with increasing frequency in studies and may motivate the request for endoscopy examinations. However, the risk associated with infection with SARS-CoV-2 does not seem to have been sufficiently taken into account in endoscopy centers in the 3 countries.
基金a grant from the National Science Center,Poland(Grant No.2016/23/B/NZ9/03427)co-financed within the framework of the Polish Ministry of Science and Higher Education’s program:“Regional Initiative Excellence”in the years 2019–2022(No.005/RID/2018/19)“financing amount 12000000,00 PLN”。
文摘Background:The use of industrial by-products rich in bioactive compounds as animal feeds can reduce greenhouse gas production.Paulownia leaves silage(PLS)was supplemented to dairy cows'diet and evaluated in vitro(Exp.1;Rusitec)and in vivo(Exp.2,cannulated lactating dairy cows and Exp.3,non-cannulated lactating dairy cows).The study investigated the PLS effect on ruminal fermentation,microbial populations,methane production and concentration,dry matter intake(DMI),and fatty acid(FA)proportions in ruminal fluid and milk.Results:Several variables of the ruminal fluid were changed in response to the inclusion of PLS.In Exp.1,the p H increased linearly and quadratically,whereas ammonia and total volatile fatty acid(VFA)concentrations increased linearly and cubically.A linear,quadratic,and cubical decrease in methane concentration was observed with increasing dose of the PLS.Exp.2 revealed an increase in ruminal p H and ammonia concentrations,but no changes in total VFA concentration.Inclusion of PLS increased ruminal propionate(at 3 h and 6 h after feeding),isovalerate,and valerate concentrations.Addition of PLS also affected several populations of the analyzed microorganisms.The abundances of protozoa and bacteria were increased,whereas the abundance of archaea were decreased by PLS.Methane production decreased by 11%and 14%in PLS-fed cows compared to the control in Exp.2 and 3,respectively.Exp.3 revealed a reduction in the milk protein and lactose yield in the PLS-fed cows,but no effect on DMI and energy corrected milk yield.Also,the PLS diet affected the ruminal biohydrogenation process with an increased proportions of C18:3 cis-9 cis-12 cis-15,conjugated linoleic acid,C18:1 trans-11 FA,polyunsaturated fatty acids(PUFA),and reduced n6/n3 ratio and saturated fatty acids(SFA)proportion in milk.The relative transcript abundances of the 5 of 6 analyzed genes regulating FA metabolism increased.Conclusions:The dietary PLS replacing the alfalfa silage at 60 g/kg diet can reduce the methane emission and improve milk quality with greater proportions of PUFA,including conjugated linoleic acid,and C18:1 trans-11 along with reduction of SFA.
文摘BACKGROUND Israel has a high rate of Jewish immigration and a high prevalence of inflammatory bowel disease(IBD).AIM To compare IBD prevalence in first-generation immigrants vs Israel-born Jews.METHODS Patients with a diagnosis of IBD as of June 2020 were included from the validated epi-IIRN(Israeli IBD Research Nucleus)cohort that includes 98%of the Israeli population.We stratified the immigration cohort by IBD risk according to country of origin,time period of immigration,and age group as of June 2020.RESULTS A total of 33544 patients were ascertained,of whom 18524(55%)had Crohn’s disease(CD)and 15020(45%)had ulcerative colitis(UC);28394(85%)were Israel-born and 5150(15%)were immigrants.UC was more prevalent in immigrants(2717;53%)than in non-immigrants(12303,43%,P<0.001),especially in the<1990 immigration period.After adjusting for age,longer duration in Israel was associated with a higher point prevalence rate in June 2020(high-risk origin:Immigration<1990:645.9/100000,≥1990:613.2/100000,P=0.043;intermediate/low-risk origin:<1990:540.5/100000,≥1990:192.0/100000,P<0.001).The prevalence was higher in patients immigrating from countries with high risk for IBD(561.4/100000)than those originating from intermediate-/low-risk countries(514.3/100000;P<0.001);non-immigrant prevalence was 528.9/100000.CONCLUSION Lending support to the environmental effect on IBD etiology,we found that among immigrants to Israel,the prevalence of IBD increased with longer time since immigration,and was related to the risk of IBD in the country of origin.The UC rate was higher than that of CD only in those immigrating in earlier time periods.
文摘A class of nonlinear nonlocal for singularly perturbed Robin initial boundary value problems for reaction diffusion equations is considered. Under suitable conditions, firstly, the outer solution of the original problem is obtained, secondly, using the stretched variable, the composing expansion method and the expanding theory of power series the initial layer is constructed, finally, using the theory of differential inequalities the asymptotic behavior of solution for the initial boundary value problems are studied and educing some relational inequalities the existence and uniqueness of solution for the original problem and the uniformly valid asymptotic estimation is discussed.
文摘Chronic hepatitis B(CHB)is a global health issue that increases the risk of liver cirrhosis and hepatocellular carcinoma in infected patients.Metabolic syndrome(Met S)is a disease endemic mostly to the developed countries.It is associated with high cardiovascular mortality and morbidity,diabetes mellitus as well as cancer.In this manuscript,we systematically review the published data on the relationship between Met S and CHB infection.Multiple studies have described highly variable correlations between CHB on one hand and Met S,non-alcoholic fatty liver disease and dyslipidemia on the other.No association between CHB and diabetes mellitus or atherosclerosis has been described as of now.The presence of Met S in patients infected with hepatitis B virus increases the risk of fibrosis,cirrhosis and hepatocellular carcinoma.Appropriate lifestyle,but also pharmacological interventions are needed to prevent the development of these complications.
基金This work was supported by the National High Technology Research and Development Program of China (863 Program, Grant No. 2002AA135360), the National Natural Science Foundation of China (Grant No. 40271025), the National Key Research Project (Grant No.
文摘Nowadays, the material recycling is a growing trend in development of building materials and therefore using of secondary raw materials for production new building materials is in accordance with sustainable development in civil engineering. Therefore, it is increasingly becoming crucial to accelerate the transition from application of non-renewable sources of raw materials to renewable raw materials. One fast renewable resource is natural plant fibers. The use of the cellulosic fibers as environmentally friendly material in building products contributes to the environmental protection and saves non-renewable resources of raw materials. Wood fibers and recycled cellulose fibers of waste paper appear as suited reinforcing elements for cement-based materials. In this paper, there is used application of Fourier transform infrared spectroscopy (FTIR) on cellulose fibers coming from different sources. FTIR spectra of cellulose fiber samples are investigated and compared with reference sample of cellulose.
基金supported by the National Natural Science Foundation of China(20776089)the Fundamental Research Funds for the Central Universities(2014NZYQN20)
文摘Doping effects of manganese (Mn) on catalytic performance and structure evolution of NiMgO catalysts for synthesis of multi-walled carbon nanotubes (MWCNTs) from methane were investigated for the first time. Addition of Mn in NiMgO catalyst can greatly improve the MWCNTs yield. Mno.2NiMgO catalyst among the tested ones gives the highest MWCNTs yield as 2244%, which is two times higher than that of the catalyst without Mn. The structure evolution, reduction behaviors and surface chemical properties of MnNiMgO catalysts with various Mn contents were studied in detail. It was found that the stable solid solution of NiMgO2 formed in NiMgO catalyst was disturbed by the addition of Mn. Instead, another solid solution of MnMg608 is formed. More amount of Ni can be reduced and dispersed on the catalyst surface to be acted as active sites. Importantly, the changes of Ni content on the surface are correlated with the Ni particle size and the outer diameter of MWCNTs, suggesting the controllable synthesis of MWCNTs over MnNiMgO catalysts.
文摘Ionizing radiation caused by medical treatments,nuclear events or even space flights can irreversibly damage structure and function of brain cells.That can result in serious brain damage,with memory and behavior disorders,or even fatal oncologic or neurodegenerative illnesses.Currently used treatments and drugs are mostly targeting biochemical processes of cell apoptosis,radiation toxicity,neuroinflammation,and conditions such as cognitive-behavioral disturbances or others that result from the radiation insult.With most drugs,the side effects and potential toxicity are also to be considered.Therefore,many agents have not been approved for clinical use yet.In this review,we focus on the latest and most effective agents that have been used in animal and also in the human research,and clinical treatments.They could have the potential therapeutical use in cases of radiation damage of central nervous system,and also in prevention considering their radioprotecting effect of nervous tissue.
基金This work was funded by the Russian Science Foundation(Grant No.17-79-20162-П).
文摘Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers.This is done in order to provide for fast transportation through the North Sea Route and safe operation in extreme ice conditions.Currently,new large size gas and oil carriers and container ships are being designed and built with beams much greater than the beams of existing icebreakers.At the same time,no mathematical description exists for the breaking mechanism of ice channel edges,when such vessels move under icebreaker escort.This paper suggests a simple method for assessment of the ice resistance in the case of a large ship running in an icebreaker channel;the method is based on modification of well-known semi-empirical methods for calculation of the ice resistance to ships in level and broken ice.The main feature of the proposed calculation scheme consists in that different methods are applied to estimate the ice resistance in broken ice and due to breaking of level ice edges.The combination of these methods gives a deliverable ice resistance of a large size vessel moving under icebreaker assistance in a newly made ice channel.In general,proposed method allows to define the speed of a carrier moving in an ice channel behind a modern linear icebreaker and could be applied at the ship design stage and during development of the marine transportation system.The paper also discusses the ways for further refinement of the assessment procedure suggested.
文摘The ocean current response to a hurricane on the shelf-break is examined. The study area is the DeSoto Canyon in the northeast Gulf of Mexico, and the event is the passage of 1998 Hurricane Georges with a maximum wind speed of 49 m/s. The data sets used for analysis consist of the mooring data taken by the Field Program of the DeSoto Canyon Eddy Intrusion Study, and simultaneous winds observed by NOAA (National Oceanic and Atmospheric Administration) Moored Buoy 42040. Time-depth ocean current energy density images derived from the observed data show that the ocean currents respond almost immediately to the hurricane with important differences on and offthe shelf. On the shelf, in the shallow water of 100 m, the disturbance penetrates rapidly downward to the bottom and forms two energy peaks, the major peak is located in the mixed layer and the secondary one in the lower layer. The response dissipates quickly after external forcing disappears. Offthe shelf, in the deep water, the major disturbance energy seems to be trapped in the mixed layer with a trailing oscillation; although the disturbance signals may still be observed at the depths of 500 and 1 290 m. Vertical dispersion analysis reveals that the near-initial wave packet generated offthe shelf consists of two modes. One is a barotropic wave mode characterized by a fast decay rate of velocity amplitude of 0.020 s^-, and the other is baroclinic wave mode characterized by a slow decay rate of 0.006 9 s^-1. The band-pass-filtering and empirical function techniques are employed to the frequency analysis. The results indicate that ialf frequencies shift above the local inertial frequency. On the shelf, the average frequency is 1.04fin the mixed layer, close to the diagnosed frequency of the first baroclinic mode, and the average frequency increases to 1.07fin the thermocline. Offthe shelf, all frequencies are a little smaller than the diagnosed frequency of the first mode. The average frequency decreases from 1.035fin the mixed layer to 1.02fin the thermocline, implying a trend for the shift in frequency of the oscillations towards f with the depth.
基金This study was supported jointly by the Project ZKCX2-SW-210the"National Key Programme for Developing Basic Sciences of China"(G1998040900)the National Natural Science Foundation of China under Grant No.40135020.
文摘Possible influences of the Barents Sea ice anomalies on the Eurasian atmospheric circulation and the East China precipitation distribution in the late spring and early summer (May-June) are investigated by analyzing the observational data and the output of an atmospheric general circulation model (AGCM). The study indicates that the sea ice condition of the Barents Sea from May to July may be interrelated with the atmospheric circulation of June. When there is more than average sea ice in the Barents Sea, the local geopotential height of the 500-hPa level will decrease, and the same height in the Lake Baikal and Okhotsk regions will increase and decrease respectively to form a wave-chain structure over North Eurasia. This kind of anomalous height pattern is beneficial to more precipitation in the south part of East China and less in the north.