Jadomycin is an antibiotic that has shown activities against bacteria, yeasts and fungi as well as cytotoxic properties to cancer cells. Because of the wide range of its inhibitory actions, jadomycin shows promise as ...Jadomycin is an antibiotic that has shown activities against bacteria, yeasts and fungi as well as cytotoxic properties to cancer cells. Because of the wide range of its inhibitory actions, jadomycin shows promise as a novel antibiotic and cancer treatment drug. Streptomyces venezuelae are aerobic bacteria that produce jadomycin and the size of bacterial population can significantly affect the yield of jadomycin. Therefore, the bacterial population must be accurately measured in order to standardize the reproducibility of jadomycin production process. In this study, a dehydrogenase activity measurement test, using triphenyl tetrazolium chloride (TTC), was used to measure the dehydrogenase activity of Streptomyces venezuelae during growth in maltose-yeast extract-malt extract (MYM) broth. The aims were to evaluate the effectiveness of the test for measuring microbial growth and to study the effects of the test conditions (incubation time, incubation temperature and medium pH) on triphenyl formazan (TF) yield. The results showed that the TF yield was highly correlated to the optical density. The highest TF yield was observed at a pH of 6 at all incubation times and temperature. Lower TF yields were obtained at higher temperature (40 and 50oC) compared to those obtained at lower temperatures (22 and 30oC). The difference between the yields obtained at 22oC and 30oC were not significant. The differences between incubation time were also not significant. The recommended test conditions are an incubation time of 1 hour at a temperature of 30oC and a pH of 6 followed by three extractions using methanol.展开更多
East Venezuela盆地是一个大型的不对称前陆盆地,具有丰富油气资源。古生代以来,经历了晚三叠世—侏罗纪裂谷、白垩纪—始新世被动边缘和渐新世至今前陆盆地3个演化阶段。纵向上沉积地层可划分为前白垩系、白垩系和后白垩系3套巨层序。E...East Venezuela盆地是一个大型的不对称前陆盆地,具有丰富油气资源。古生代以来,经历了晚三叠世—侏罗纪裂谷、白垩纪—始新世被动边缘和渐新世至今前陆盆地3个演化阶段。纵向上沉积地层可划分为前白垩系、白垩系和后白垩系3套巨层序。East Venezuela盆地最主要的烃源岩是Guayuta群和Tigre组海相泥页岩和碳酸盐岩。生油岩成熟度由北往南递减。北部烃源灶油气经断层、砂体长距离阶梯式向南部斜坡边缘运移。盆地最主要圈闭类型为背斜、断块、地层和岩性圈闭。Oficina组构造、构造—地层、地层圈闭组合和Naricual组构造圈闭组合是盆地内最主要的两套成藏组合。有潜力的勘探领域包括白垩系—下中新统被动边缘沉积层序、盆地中部前渊区、南部重油带和东部海域。展开更多
The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second larg...The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second largest production and consumption center of liquid fuel, and is also the world＇s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world＇s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world＇s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle- Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural- unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic- structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area.展开更多
To investigate the efficiency and stability of Venezuela＇s oil-oriented economy, this paper applied entropy to the analysis.Based on this method, Venezuela＇s oil-centered industry, inefficient regulatory system, and...To investigate the efficiency and stability of Venezuela＇s oil-oriented economy, this paper applied entropy to the analysis.Based on this method, Venezuela＇s oil-centered industry, inefficient regulatory system, and insensitive response to external changes are recognized as an increase in the country＇s entropy. According to these facts, a dissipative structure model is constructed to analyze the efficiency and stability of the Venezuela＇s economic system. The results show that financial assistants（fund flow）, policy reform（policy flow）, and advanced technology（technology flow） can perform as negative entropy inflows（NEIFs）. These NEIFs will promote a series of influence and feedback reactions, which will contribute to recovering Venezuela＇s system efficiency and stability.展开更多
The purpose of the research was to obtain the mass wasting hazard map for the state of Vargas, central coast of Venezuela, using GIS technology. The work was developed through the heuristic method with the generation ...The purpose of the research was to obtain the mass wasting hazard map for the state of Vargas, central coast of Venezuela, using GIS technology. The work was developed through the heuristic method with the generation of thematic digital maps, univariate statistical treatment, weighting of each variable and quantifying the relationship of each parameter unit regarding mass wasting processes. The algorithm designed to perform map algebra was designed using the variables: surface geology, slope, slope orientation, terrain curvature, moisture topographic index, power index surface flow rate and capacity sediment transport and the rate normalized difference vegetation. The results show a distribution of landslide hazard with the highest values in the west central part of Vargas state, where the dominant lithology is incompetent, and combined with topographic elements, determining high instability, meanwhile the lower hazard areas were found in specific areas such as the middle watershed areas east of the state. The calibration of this model shows a reliability of 80%, so it is highly advisable to use the information generated in this work by governmental and non-governmental organizations in the planning, management and use of land.展开更多
During 15 months the white shrimp (Litopenaeus schmitti) fishing zone was characterized ecologically through the obtaining, compilation and analysis of environmental and physicochemical variables, and modeled the dist...During 15 months the white shrimp (Litopenaeus schmitti) fishing zone was characterized ecologically through the obtaining, compilation and analysis of environmental and physicochemical variables, and modeled the distribution of the relative abundance (CPUE) obtained in 21 fishing sites according to the environmental structure defined by the studied variables. A two-way factorial ANOVA with interaction was used to examine the spatial (fishing sites) and temporal (months) dynamics of CPUE, and a principal component analysis (PCA) was used to discern the environmental structure of the study area. To determine if the environmental structure modeled the distribution of white shrimp, the CPUE values were superimposed on maps of the study area showing strata of the most important physicochemical variables identified by PCA. ANOVA confirmed that the CPUE differed significantly among months (F = 15.6;GL = 11;P P = 0.1979);the interaction term was also not significant (F = 0.52;GL = 10;P = 0.8561). The superimposing of the CPUE on temperature and depth strata confirmed that white shrimp showed greater preference for intermediate temperatures and depths. Petróleos de Venezuela, S.A (PDVSA) contemplates the construction of a multiuse pipeline traversing the study area, by which the current environmental structure of the study area is prone to disturbance. Given the precedent effects represented by an aqueduct construction, it seems PDVSA should anticipate measures to minimize its impact on the fisheries of the zone, particularly on the white shrimp fishery.展开更多
This study represents the first comprehensive analysis of the residency patterns of a coastal population of bottlenose dolphin off the coast of Aragua,Venezuela,over a multi-year period.Using photo-identification,the ...This study represents the first comprehensive analysis of the residency patterns of a coastal population of bottlenose dolphin off the coast of Aragua,Venezuela,over a multi-year period.Using photo-identification,the most recent study(2019-2020)identified 56 individuals with the time between encounters from one to 344 days between the first and last sighting.Site Fidelity(SF)and Residence(RES)indices were calculated and Agglomerative Hierarchical Clustering(AHC)modeling was performed,with three patterns of residence obtained:resident(25%),semi-resident(17.86%)and transient(57.14%).These results were contrasted with remodeled data from a previous study(2006-2007),showing similar patterns:resident(24.44%),semi-resident(28.89%)and transient(46.67%).Importantly,two individuals were found to have been resident over the extended period.A breeding female sighted for the first time in 2004 and again in 2020(16 years)and the other from 2005 to 2020(15 years).This region is an important area for marine mammals,known to support a resident reproductive population over many years,as well seabirds,sea turtles,whale sharks and fishermen.We recommend that consideration be given to designating the waters as a Marine Protected Area to safeguard the existing population and provide benefit to the surrounding marine environment.展开更多
American media routinely criticizes countries designated by the U.S.Government as geopolitical adversaries-such as China,Cuba,Venezuela and Russia-for alleged restrictions on free expression and deviations from libera...American media routinely criticizes countries designated by the U.S.Government as geopolitical adversaries-such as China,Cuba,Venezuela and Russia-for alleged restrictions on free expression and deviations from liberal human rights norms.These nations are often branded"authoritarian",accused of stifling speech,press and assembly-rights the U.S.claims to champion.展开更多
The focus of the Hazus earthquake model has been largely U.S. centric due to a lack of standardized building-infrastructure data formats applicable elsewhere.In a combined effort between FEMA Region VIII and the Unive...The focus of the Hazus earthquake model has been largely U.S. centric due to a lack of standardized building-infrastructure data formats applicable elsewhere.In a combined effort between FEMA Region VIII and the Universidad de Los Andes, Venezuela, the present study uses the Hazus 2.1 software to simulate earthquake loss estimations for Venezuela. Population totals and demographic distributions were developed using Oak Ridge National Labs Landscan 2008 population data and the census 2011 for Venezuela. The accuracy of the model was further enhanced for Me′rida State, located in western Venezuela, by collecting, incorporating, and developing region and specific inventories including soil maps, liquefaction and landslide susceptibility studies, demographic data, and building inventory information. We used USGS Shake Maps scenarios for two potential earthquake events with peak ground accelerations proposed within Performance Based Seismic Engineering of Buildings, VISION 2000 recommendations. The region has not witnessed an earthquake with a magnitude greater than M 7 in the last120 years. Given the historical record of seismicity and the seismotectonics in the region, it becomes increasingly important to understand the potential implications from moderate to large earthquakes in Me′rida State, Venezuela.展开更多
Background Malaria remains a leading public health problem worldwide.Co-infections with other pathogens complicate its diagnosis and may modify the disease’s clinical course and management.Similarities in malaria cli...Background Malaria remains a leading public health problem worldwide.Co-infections with other pathogens complicate its diagnosis and may modify the disease’s clinical course and management.Similarities in malaria clinical presentation with other infections and overlapping endemicity result in underdiagnosis of co-infections and increased mortality.Thus,the aim of this study was to determine the seroprevalence of viral and bacterial pathogens among diagnosed malaria patients in malaria-endemic areas in Venezuela.Methods A cross-sectional study was conducted on malaria patients attending three reference medical centres in Ciudad Bolivar,Venezuela.Clinical evaluation and laboratory tests for dengue virus(DENV),chikungunya virus(CHIKV),viral hepatitis[hepatitis A virus(HAV),hepatitis B virus(HBV),and hepatitis C virus(HCV)],and leptospirosis(LEP)were performed by enzyme-linked immunosorbent assays.Previous exposure to these pathogens was defined by the presence of specific immunoglobulin(Ig)G,and co-infection or recent exposure(CoRE)was determined by the presence of specific IgM alone or IgM+IgG.Data analysis considered descriptive statistics.Parameter distribution was statistically evaluated using Kolmogorov–Smirnov test and the necessary comparison tests.Odds ratio(OR)for complications was determined according to CoRE presence with a 95%confidence interval(CI).Results A total of 161 malaria patients were studied,66%infected with Plasmodium vivax,27%with P.falciparum,and 7.5%harboured P.vivax/P.falciparum mixed infection.Previous exposure to DENV(60%)and CHIKV(25%)was frequent.CoRE was confirmed in 55 of the 161 malaria patients(34%)and were more frequent in P.falciparum(49%)than in P.vivax(29%)and mixed malaria patients(25%)(OR=2.43,95%CI:1.39–4.25,P=0.018).The most frequent CoRE was DENV(15%),followed by HAV(12%),HBV(6.2%),CHIKV(5.5%),and LEP(3.7%);HCV CoRE was absent.Complicated malaria was significantly more frequent in patients with CoRE(56%)than those without CoRE(36%;OR=2.31,95%CI:1.18–4.92,P=0.013).Conclusions We found high CoRE prevalence in malaria patients as determined by serology in the study region;cases were associated with a worse clinical outcome.Further prospective studies with samples from different infection sites and the use of molecular tools are needed to determine the clinical significance of these findings.展开更多
文摘Jadomycin is an antibiotic that has shown activities against bacteria, yeasts and fungi as well as cytotoxic properties to cancer cells. Because of the wide range of its inhibitory actions, jadomycin shows promise as a novel antibiotic and cancer treatment drug. Streptomyces venezuelae are aerobic bacteria that produce jadomycin and the size of bacterial population can significantly affect the yield of jadomycin. Therefore, the bacterial population must be accurately measured in order to standardize the reproducibility of jadomycin production process. In this study, a dehydrogenase activity measurement test, using triphenyl tetrazolium chloride (TTC), was used to measure the dehydrogenase activity of Streptomyces venezuelae during growth in maltose-yeast extract-malt extract (MYM) broth. The aims were to evaluate the effectiveness of the test for measuring microbial growth and to study the effects of the test conditions (incubation time, incubation temperature and medium pH) on triphenyl formazan (TF) yield. The results showed that the TF yield was highly correlated to the optical density. The highest TF yield was observed at a pH of 6 at all incubation times and temperature. Lower TF yields were obtained at higher temperature (40 and 50oC) compared to those obtained at lower temperatures (22 and 30oC). The difference between the yields obtained at 22oC and 30oC were not significant. The differences between incubation time were also not significant. The recommended test conditions are an incubation time of 1 hour at a temperature of 30oC and a pH of 6 followed by three extractions using methanol.
基金financially supported by the National Natural Science Foundation of China(grant No.41402219)
文摘The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second largest production and consumption center of liquid fuel, and is also the world＇s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world＇s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world＇s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle- Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural- unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic- structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area.
基金funded by the National Natural Science Foundation of China (Grant Nos. 71273021 and 7167030506)
文摘To investigate the efficiency and stability of Venezuela＇s oil-oriented economy, this paper applied entropy to the analysis.Based on this method, Venezuela＇s oil-centered industry, inefficient regulatory system, and insensitive response to external changes are recognized as an increase in the country＇s entropy. According to these facts, a dissipative structure model is constructed to analyze the efficiency and stability of the Venezuela＇s economic system. The results show that financial assistants（fund flow）, policy reform（policy flow）, and advanced technology（technology flow） can perform as negative entropy inflows（NEIFs）. These NEIFs will promote a series of influence and feedback reactions, which will contribute to recovering Venezuela＇s system efficiency and stability.
文摘The purpose of the research was to obtain the mass wasting hazard map for the state of Vargas, central coast of Venezuela, using GIS technology. The work was developed through the heuristic method with the generation of thematic digital maps, univariate statistical treatment, weighting of each variable and quantifying the relationship of each parameter unit regarding mass wasting processes. The algorithm designed to perform map algebra was designed using the variables: surface geology, slope, slope orientation, terrain curvature, moisture topographic index, power index surface flow rate and capacity sediment transport and the rate normalized difference vegetation. The results show a distribution of landslide hazard with the highest values in the west central part of Vargas state, where the dominant lithology is incompetent, and combined with topographic elements, determining high instability, meanwhile the lower hazard areas were found in specific areas such as the middle watershed areas east of the state. The calibration of this model shows a reliability of 80%, so it is highly advisable to use the information generated in this work by governmental and non-governmental organizations in the planning, management and use of land.
文摘During 15 months the white shrimp (Litopenaeus schmitti) fishing zone was characterized ecologically through the obtaining, compilation and analysis of environmental and physicochemical variables, and modeled the distribution of the relative abundance (CPUE) obtained in 21 fishing sites according to the environmental structure defined by the studied variables. A two-way factorial ANOVA with interaction was used to examine the spatial (fishing sites) and temporal (months) dynamics of CPUE, and a principal component analysis (PCA) was used to discern the environmental structure of the study area. To determine if the environmental structure modeled the distribution of white shrimp, the CPUE values were superimposed on maps of the study area showing strata of the most important physicochemical variables identified by PCA. ANOVA confirmed that the CPUE differed significantly among months (F = 15.6;GL = 11;P P = 0.1979);the interaction term was also not significant (F = 0.52;GL = 10;P = 0.8561). The superimposing of the CPUE on temperature and depth strata confirmed that white shrimp showed greater preference for intermediate temperatures and depths. Petróleos de Venezuela, S.A (PDVSA) contemplates the construction of a multiuse pipeline traversing the study area, by which the current environmental structure of the study area is prone to disturbance. Given the precedent effects represented by an aqueduct construction, it seems PDVSA should anticipate measures to minimize its impact on the fisheries of the zone, particularly on the white shrimp fishery.
基金We thank the fisherman José“Cata”,Grisel Velásquez(UNISIG-IVIC),Laboratory of Ecosystems and Global Change,Venezuelan Institute of Scientific Research,PADI Foundation(N°40470)the Cetacean Society International and the Society of Marine Mammalogy for their funding which enabled this study.
文摘This study represents the first comprehensive analysis of the residency patterns of a coastal population of bottlenose dolphin off the coast of Aragua,Venezuela,over a multi-year period.Using photo-identification,the most recent study(2019-2020)identified 56 individuals with the time between encounters from one to 344 days between the first and last sighting.Site Fidelity(SF)and Residence(RES)indices were calculated and Agglomerative Hierarchical Clustering(AHC)modeling was performed,with three patterns of residence obtained:resident(25%),semi-resident(17.86%)and transient(57.14%).These results were contrasted with remodeled data from a previous study(2006-2007),showing similar patterns:resident(24.44%),semi-resident(28.89%)and transient(46.67%).Importantly,two individuals were found to have been resident over the extended period.A breeding female sighted for the first time in 2004 and again in 2020(16 years)and the other from 2005 to 2020(15 years).This region is an important area for marine mammals,known to support a resident reproductive population over many years,as well seabirds,sea turtles,whale sharks and fishermen.We recommend that consideration be given to designating the waters as a Marine Protected Area to safeguard the existing population and provide benefit to the surrounding marine environment.
文摘American media routinely criticizes countries designated by the U.S.Government as geopolitical adversaries-such as China,Cuba,Venezuela and Russia-for alleged restrictions on free expression and deviations from liberal human rights norms.These nations are often branded"authoritarian",accused of stifling speech,press and assembly-rights the U.S.claims to champion.
文摘The focus of the Hazus earthquake model has been largely U.S. centric due to a lack of standardized building-infrastructure data formats applicable elsewhere.In a combined effort between FEMA Region VIII and the Universidad de Los Andes, Venezuela, the present study uses the Hazus 2.1 software to simulate earthquake loss estimations for Venezuela. Population totals and demographic distributions were developed using Oak Ridge National Labs Landscan 2008 population data and the census 2011 for Venezuela. The accuracy of the model was further enhanced for Me′rida State, located in western Venezuela, by collecting, incorporating, and developing region and specific inventories including soil maps, liquefaction and landslide susceptibility studies, demographic data, and building inventory information. We used USGS Shake Maps scenarios for two potential earthquake events with peak ground accelerations proposed within Performance Based Seismic Engineering of Buildings, VISION 2000 recommendations. The region has not witnessed an earthquake with a magnitude greater than M 7 in the last120 years. Given the historical record of seismicity and the seismotectonics in the region, it becomes increasingly important to understand the potential implications from moderate to large earthquakes in Me′rida State, Venezuela.
文摘Background Malaria remains a leading public health problem worldwide.Co-infections with other pathogens complicate its diagnosis and may modify the disease’s clinical course and management.Similarities in malaria clinical presentation with other infections and overlapping endemicity result in underdiagnosis of co-infections and increased mortality.Thus,the aim of this study was to determine the seroprevalence of viral and bacterial pathogens among diagnosed malaria patients in malaria-endemic areas in Venezuela.Methods A cross-sectional study was conducted on malaria patients attending three reference medical centres in Ciudad Bolivar,Venezuela.Clinical evaluation and laboratory tests for dengue virus(DENV),chikungunya virus(CHIKV),viral hepatitis[hepatitis A virus(HAV),hepatitis B virus(HBV),and hepatitis C virus(HCV)],and leptospirosis(LEP)were performed by enzyme-linked immunosorbent assays.Previous exposure to these pathogens was defined by the presence of specific immunoglobulin(Ig)G,and co-infection or recent exposure(CoRE)was determined by the presence of specific IgM alone or IgM+IgG.Data analysis considered descriptive statistics.Parameter distribution was statistically evaluated using Kolmogorov–Smirnov test and the necessary comparison tests.Odds ratio(OR)for complications was determined according to CoRE presence with a 95%confidence interval(CI).Results A total of 161 malaria patients were studied,66%infected with Plasmodium vivax,27%with P.falciparum,and 7.5%harboured P.vivax/P.falciparum mixed infection.Previous exposure to DENV(60%)and CHIKV(25%)was frequent.CoRE was confirmed in 55 of the 161 malaria patients(34%)and were more frequent in P.falciparum(49%)than in P.vivax(29%)and mixed malaria patients(25%)(OR=2.43,95%CI:1.39–4.25,P=0.018).The most frequent CoRE was DENV(15%),followed by HAV(12%),HBV(6.2%),CHIKV(5.5%),and LEP(3.7%);HCV CoRE was absent.Complicated malaria was significantly more frequent in patients with CoRE(56%)than those without CoRE(36%;OR=2.31,95%CI:1.18–4.92,P=0.013).Conclusions We found high CoRE prevalence in malaria patients as determined by serology in the study region;cases were associated with a worse clinical outcome.Further prospective studies with samples from different infection sites and the use of molecular tools are needed to determine the clinical significance of these findings.
