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
Mountains are important reservoirs of biodiversity and endemism on a global scale, but little is known about the altitudinal configuration of this diversity and its driving factors in arid mountains. We explored varia...Mountains are important reservoirs of biodiversity and endemism on a global scale, but little is known about the altitudinal configuration of this diversity and its driving factors in arid mountains. We explored variations in composition, diversity, cover,and life forms of vascular plants along a complete altitudinal gradient(1300-4000 m a.s.l) in Sierra de Velasco, an arid mountain in northwestern Argentina.We evaluated the influence of environmental variables on plant diversity and cover. Field sampling was conducted in the northern sector of the Sa. de Velasco,on the western slope in eight 50 m wide altitudinal bands at 400 m elevation intervals. We used rectangular plots(20 × 4 m;n:10/altitudinal band) to register the vascular plants of all the growth forms, and linear transects(20 m long.;n:30/altitudinal band) to quantify the vegetation cover using the point intercept method. Diversity was calculated using hill numbers.Data analysis included non-metric multidimensional scaling(NMDS), indicator species analysis,generalized linear models(GLMs), and variance partitioning analysis. A total of 232 species from 51families and 158 genera were registered. Species composition showed greater similarity at intermediate elevations. Plant diversity and cover exhibited a unimodal distribution, peaking at intermediate elevations(2100-2500 m). In contrast, life forms' distribution showed divergent patterns. Therophytes and succulents predominated at low altitudes,phanerophytes and hemicryptophytes at medium altitudes, and chamaephytes and geophytes at high altitudes. The altitudinal patterns of plant diversity and cover were primarily driven by climatic factors.Conservation efforts in the Sierra de Velasco should focus on the middle and upper zones due to their high biodiversity and vulnerability to climate change.展开更多
Unstable environments intensify the frequency of extreme disasters.Long-term climate changes can lead to agricultural and ecological degradation that threatens population sustainability.To better understand past clima...Unstable environments intensify the frequency of extreme disasters.Long-term climate changes can lead to agricultural and ecological degradation that threatens population sustainability.To better understand past climatic events and consequences,here we present a reconstruction of the self-calibrating Palmer drought severity index(scPDSI)from September to August for the desert margins of northern China,dating back to 1742.The reconstruction accounts for 42.9%of the variation of meteorological data between 1951 and 2020.Our spatial correlation analyses showed significant correlations between scPDSI,runoff,and precipitation.Over the past 279 years,the study area has undergone nine dry and eight wet periods,with the most severe climate extremes between the 1850s and 1890s.This period of prolonged drought in northeastern China coincided with the combined impacts of climatic factors and human influences,contributing to the fall of the Qing Dynasty.Analysis of periodicity and anomalies in sea surface temperatures indicate a strong association between wet and dry cycles and El Niño-Southern Oscillations.Our findings offer insights into long-term dry and wet fluctuations at the desert margins in northern China and elucidate the relationship between drought and the dynamics of civilizations.They also highlight the potential impact of extremes in climate on modern society,especially under the four projected shared socioeconomic pathways climatic scenarios,which predict worsening droughts in northern China.展开更多
Aluminum alloy samples, 6061-T6 and 2219-T42, were exposed to Caribbean seawater for 90 d. The fluctuations of open circuit potential, considered as electrochemical noise (EN), were used to characterize and compare in...Aluminum alloy samples, 6061-T6 and 2219-T42, were exposed to Caribbean seawater for 90 d. The fluctuations of open circuit potential, considered as electrochemical noise (EN), were used to characterize and compare initial pitting events, which appeared on their surfaces. EN analysis was carried out using the power spectral density (PSD) vs frequency. The decrease of the β exponent in PSD graphs indicated a release of spontaneous energy with the progress of pit formation in seawater. The fluctuations were associated with the breakdown and formation of new corrosion layers. The values of β exponent in PSD graphs suggest that corrosion process of AA2219-T42 alloy occurs as a persistent non-stationary process, the dynamics of which is controlled by fractional Brownian motion (fBm), while on AA6061-T6 alloy the corrosion process was dominated by stationary and weakly persistent features, with the contribution of fractional Gaussian noise (fGn). After the exposure in seawater, SEM-EDX analysis revealed insoluble intermetallic particles on the alloys, rich in Cu or Fe and irregularly distributed. The preferential dissolution of Mg and Al occurs from the S-phase (Al2CuMg) of AA2219-T42 alloy.展开更多
Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination...Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.展开更多
Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic ...Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic acid(TERT), with 4,4′-(hexafluoroisopropylidene)dianiline(HFA) or 2,3,5,6-tetramethyl-1,4-phenylenediamine(Durene) by direct polycondensation. The structures of the obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1 H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 and 1.60 nm, respectively. Moreover, they presented good thermal stability up to300 °C. Young's moduli of the co-polyamide films were between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films were amorphous due to the incorporation of both bulky pendant groups, tert-butyl and dibenzobarrelene. The combination of bulky pendant groups provided intrinsically transparent co-polyamide films with a transmittance higher than 88% in the range of 400-780 nm.Due to these outstanding film and optical properties, they are suggested to be flexible substrates in applications for solar cell and other portable electronic devices.展开更多
The extraction of anthocyanins present in the skin of the dragon fruit was performed using trifluoroacetic acid (TFA) plus a mixture of methanol, acetic acid and water;the anthocyanins were then purified with a LC-18 ...The extraction of anthocyanins present in the skin of the dragon fruit was performed using trifluoroacetic acid (TFA) plus a mixture of methanol, acetic acid and water;the anthocyanins were then purified with a LC-18 cartridge, using methanol acidified with TFA as eluent, reaching concentrations of 44.3865 ± 1.3125 mg/100g of sample. The extracts were put through stability tests under different storage conditions, modifying the pH of the extracts (pH of 1, 4 and 6), the temperature (4℃, 25℃ and 68℃) and the absence and presence of light for a time period of 4 days;the tests indiated that anthocyanins remain more stable at a temperature of 4℃?with a pH of 4 in the absence of light, retaining up to 80% of the pigment. Three anthocyanins were partially identified in the extracts by high performance liquid chromatography (HPLC);they were: cyanidin 3-O-glucoside, cyanidin 3,5 O-glucoside and pelargonidin 3,5 O-glucoside.展开更多
The removal efficiency of Cu and Zn from swine wastewater was evaluated as effected by three variables: the hydraulic retention time (HRT) (24, 48, 72 and 96 hours), two different plant species (Typha domingensis Pers...The removal efficiency of Cu and Zn from swine wastewater was evaluated as effected by three variables: the hydraulic retention time (HRT) (24, 48, 72 and 96 hours), two different plant species (Typha domingensis Pers. and Eleocharis cellulosa) and two different sizes of filter media (5 and 15 mm) using a horizontal sub-surface flow constructed wetland. From the results, a significant difference was observed in the removal efficiency of Cu and Zn with respect to different hydraulic retention times. The best results were obtained in the HRT of 96 hours for Zn where 96% removal of Zn with Typha domingensis Pers. specie with gravel of 15 mm (experimental unit 6) was achieved. For Cu, at 72 hours of HRT, the efficiency was nearly 100% in five of the six study units (1, 2, 3, 5 and 6). In contrast, in experimental unit 4 with gravel of 15 mm and without plants, only 86% Cu removal was achieved.展开更多
The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded wi...The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.展开更多
The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this reactivity.In this work,we present Mg(OH)_(2) a...The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this reactivity.In this work,we present Mg(OH)_(2) and TiO_(2)barrier coatings to reduce the degradation of magnesium alloy(Mg-Ca-Zn)surfaces.These coatings were deposited by the anodization method and the spin-coating technique,respectively.The anodized layer was coated with TiO_(2)generated from the hydrolysis of 3%weight of TTIP(Ti[OCH(CH_(3))_(2)]_(4),Titanium(IV)isopropoxide)in 2-Propanol deposited by the spin-coating method.Studying the degradation in Ringer’s solution by electrochemical impedance spectroscopy and OCP revealed a 98%reduction in pittings in uncoated samples after 14 days of immersion.The p H measurements revealed that the TiO_(2)coating reduced the alkalization of the physiological environment,keeping the pH at 6.0 values.In vitro studies of two types of bacteria(E.coli and S.aureus)exhibited zones of inhibition in the agar and activity bactericidal(kill time test).The mechanisms behind the improved degradation resistance and enhanced antibacterial activity are presented and discussed here.Surface modification with Mg(OH)_(2)/TiO_(2)coatings is a promising strategy to control the biodegradation of magnesium implants for bone regeneration.展开更多
Respiratory disorders during sleep have as a general characteristic the alteration of the respiratory cycle while sleeping. The most outstanding characteristic of Obstructive Sleep Apnea Syndrome (OSA) is the partial ...Respiratory disorders during sleep have as a general characteristic the alteration of the respiratory cycle while sleeping. The most outstanding characteristic of Obstructive Sleep Apnea Syndrome (OSA) is the partial (hypopnea) or total (apnea) obstruction of the upper airway that occurs repeatedly during sleep. The OSA is global public health issue. When it is not treated, OSA represents a cost two or three times higher of the institutional resources for health. Studies conducted in different countries indicate that the prevalence of the OSA goes from 2% to 10% in general population. The OSA is a serious sleep disorder that has negative implications on multiple systems of the organism. It is associated with hypertension, diabetes and the metabolic syndrome. When OSA coexists with a heart disease or ischemic heart disease, it significantly raises the probability of a heart failure. The use of Continuous Positive Airway Pressure (CPAP) is so far the most effective method for OSA treatment. Intervention at different levels (physiological, educational and psychological intervention) appears to be important in adherence to CPAP treatment.展开更多
Urolithiasis (UL) is an endemic disease in Southeastern, Mexico. In order to evaluate the association of I550V polymorphism in the hNaDC-1 gene with risk for hypocitraturia and/or for UL;139 adults with UL and 132 adu...Urolithiasis (UL) is an endemic disease in Southeastern, Mexico. In order to evaluate the association of I550V polymorphism in the hNaDC-1 gene with risk for hypocitraturia and/or for UL;139 adults with UL and 132 adults without UL, were included under a case-control association study. Citrate levels in 24-h urine were quantified (citraturia). The polymorphism I550V-hNaDC-1 was determined by PCR-RFLP. Statistical analysis was performed using the STATA10.2 software. Comparison of genotype and allele frequencies between subjects with and without UL showed significant differences for genotype bb (OR = 2.34, CI: 1.19-4.59, p = 0.01) and for allele b (OR = 1.62, CI: 1.15-2.28, p = 0.005), suggesting an association with the risk for UL. Comparison of genotype and allele frequencies between subjects with hypocitraturia and subjects with normocitraturia, did not show any significant difference (p > 0.05), suggesting that this polymorphism is not associated with the risk of hypocitraturia. Interestingly, the risk for UL was increased due to an additive effect of hypocitraturia with the genotype bb (OR = 6.6, CI: 2.38-18.28, p = 0.0002) or with the allele b (OR: 4.2, CI = 2.52-6.97,展开更多
Transcranial direct current stimulation(tDCS)has been reportedly beneficial for different neurodegenerative disorders.tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallu...Transcranial direct current stimulation(tDCS)has been reportedly beneficial for different neurodegenerative disorders.tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallucination(AVH).This study aims to review the effects of tDCS on AVH in patients with schizophrenia through combining the evidence from randomized clinical trials(RCTs).The databases of PsycINFO(2000–2019),PubMed(2000–2019),EMBASE(2000–2019),CINAHL(2000–2019),Web of Science(2000–2019),and Scopus(2000–2019)were systematically searched.The clinical trials with RCT design were selected for final analysis.A total of nine RCTs were eligible and included in the review.Nine RCTs were included in the final analysis.Among them,six RCTs reported a significant reduction of AVH after repeated sessions of tDCS,whereas three RCTs did not show any advantage of active tDCS over sham tDCS.The current studies showed an overall decrease of approximately 28%of AVH after active tDCS and 10%after sham tDCS.The tDCS protocols targeting the sensorimotor frontal-parietal network showed greater treatment effects compared with the protocols targeting other regions.In this regard,cathodal tDCS over the left temporoparietal area showed inhibitory effects on AVHs.The most effective tDCS protocol on AVHs was twice-daily sessions(2 mA,20-minute duration)over 5 consecutive days(10 sessions)with the anode over the left dorsolateral prefrontal cortex and the cathode over the left temporal area.Some patient-specific and diseasespecific factors such as young age,nonsmoking status,and higher frequencies of AVHs seemed to be the predictors of treatment response.Taken together,the results of tDCS as an alternative treatment option for AVH show controversy among current literatures,since not all studies were positive.However,the studies targeting the same site of the brain showed that the tDCS could be a promising treatment option to reduce AVH.Further RCTs,with larger sample sizes,should be conducted to reach a conclusion on the efficacy of tDCS for AVH and to develop an effective therapeutic protocol for clinical setting.展开更多
The browning of fruits can be considered as an enzymatic oxidation which is believed to be one of the main causes of quality loss during post-harvest handling. The enzymes responsible for this are the oxidoreductases;...The browning of fruits can be considered as an enzymatic oxidation which is believed to be one of the main causes of quality loss during post-harvest handling. The enzymes responsible for this are the oxidoreductases;the polyphenol oxidase (PPO) (monophenol, o-diphenol, oxygen oxidoreductase;EC 1.14.18.1) belongs to this group. This enzyme, which is found in the sapodilla plum (Achras sapota), was purified using a phenylsepharose and a SephacrylS-200 columns. The molecular weight of the purified enzyme was estimated to be about 66 kDa by gel filtration and 29 kDa by SDS-PAGE. A single protein band was found using the latter system (SDS-PAGE), which shows that the PPO of the pulp of the sapodilla plum may be composed of two protein subunits with similar molecular weight. The optimum pH was 7.0 and the optimum temperature 60℃. The most effective inhibitors tested were ascorbic acid, sodium metabisulfite and acetic acid.展开更多
The hydrolysis of velvet bean (Mucuna pruriens) protein in the presence of Alcalase?-Flavourzyme? and Pepsin-Pancreatin was investigated. The results showed that Alcalase?-Flavourzyme? (29.08%) sequential system catal...The hydrolysis of velvet bean (Mucuna pruriens) protein in the presence of Alcalase?-Flavourzyme? and Pepsin-Pancreatin was investigated. The results showed that Alcalase?-Flavourzyme? (29.08%) sequential system catalyzed the hydrolysis most efficiently that Pepsin-Pancreatin (24.78%). In addition, the higher ACE-I inhibitory activity was achieved with the sequential system Alcalase?-Flavourzyme? (33.13%). Furthermore, the concentration of peptides employing an ultrafiltration (UF) system or their purification by gel filtration chromatography showed that the oligomeric peptides with lower molecular weight registered the highest ACE-I inhibitory activity. It has been demonstrated that Mucuna pruriens protein hydrolysates could serve as a source of peptides with ACE inhibitory activity and this activity can be attributed mainly to the mixture of short peptides in the hydrolysate.展开更多
To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June...To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June 2009 to April 2010 we followed the seasonal changes in S. horneri density and biomass along two intertidal transects per site. The effects of this non-indigenous species on the local macroalgae community were assessed by comparing their species composition, density, biomass, species richness, and diversity index in quadrats with and without S. horneri. There were significant differences in S. horneri density and biomass between sites (P < 0.001). At RB the invasive alga density average was 2 ± 0.94 individual m-2, with a mean biomass of 4 ± 0.95 g DW m-2. At RP, S. horneri density average was 10 ± 0.96 individual m-2, and mean biomass of 102 ± 0.97 g DW m-2. At RB, the invasive alga promoted a significant reduction in the four selected structural variables, and the corticated macrophytes and the foliose functional forms were severely reduced. At RP, there were only marginally significant effects (P = 0.06) of S. horneri presence on the local macroalgae community, and higher density, biomass, and diversity values were found when S. horneri was present. Most of the functional forms were found, even if the invasive alga was present. At both locations, the highest biomass corresponded to the articulated calcareous functional form. These contrasting results could be due to the fact that the native macroalgae community has already been altered by the early invasion of S. muticum, with the most resilient species and functional forms remaining in place. One of the most important changes we noticed is the severe reduction of the canopy forming species at both sites.展开更多
A physicochemical characterization of oil from chia seeds was carried out. Proximate composition analysis showed that fat and fiber were the principal components in the raw chia flour. Physical characterization showed...A physicochemical characterization of oil from chia seeds was carried out. Proximate composition analysis showed that fat and fiber were the principal components in the raw chia flour. Physical characterization showed that chia oil has a relative density from 0.9241, a refraction index of 1.4761 and a color with more yellow than red units. Chemical characterization showed that chia oil registered an acidity index of 2.053 mg KOH/g oil, a saponification index of 222.66 mg KOH/g oil, a content of unsaponifiable matter of 0.087%, an Iodine index of 193.45 g I/100 g oil and a peroxide index of 17.5 meq O2/kg oil. Chia oil showed a higher content of α and β linolenic and palmitic acids. Chia oil is the vegetable source with the highest content of essential fatty acids.展开更多
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Mountains are important reservoirs of biodiversity and endemism on a global scale, but little is known about the altitudinal configuration of this diversity and its driving factors in arid mountains. We explored variations in composition, diversity, cover,and life forms of vascular plants along a complete altitudinal gradient(1300-4000 m a.s.l) in Sierra de Velasco, an arid mountain in northwestern Argentina.We evaluated the influence of environmental variables on plant diversity and cover. Field sampling was conducted in the northern sector of the Sa. de Velasco,on the western slope in eight 50 m wide altitudinal bands at 400 m elevation intervals. We used rectangular plots(20 × 4 m;n:10/altitudinal band) to register the vascular plants of all the growth forms, and linear transects(20 m long.;n:30/altitudinal band) to quantify the vegetation cover using the point intercept method. Diversity was calculated using hill numbers.Data analysis included non-metric multidimensional scaling(NMDS), indicator species analysis,generalized linear models(GLMs), and variance partitioning analysis. A total of 232 species from 51families and 158 genera were registered. Species composition showed greater similarity at intermediate elevations. Plant diversity and cover exhibited a unimodal distribution, peaking at intermediate elevations(2100-2500 m). In contrast, life forms' distribution showed divergent patterns. Therophytes and succulents predominated at low altitudes,phanerophytes and hemicryptophytes at medium altitudes, and chamaephytes and geophytes at high altitudes. The altitudinal patterns of plant diversity and cover were primarily driven by climatic factors.Conservation efforts in the Sierra de Velasco should focus on the middle and upper zones due to their high biodiversity and vulnerability to climate change.
基金supported by the National Natural Science Foundation of China(32061123008).
文摘Unstable environments intensify the frequency of extreme disasters.Long-term climate changes can lead to agricultural and ecological degradation that threatens population sustainability.To better understand past climatic events and consequences,here we present a reconstruction of the self-calibrating Palmer drought severity index(scPDSI)from September to August for the desert margins of northern China,dating back to 1742.The reconstruction accounts for 42.9%of the variation of meteorological data between 1951 and 2020.Our spatial correlation analyses showed significant correlations between scPDSI,runoff,and precipitation.Over the past 279 years,the study area has undergone nine dry and eight wet periods,with the most severe climate extremes between the 1850s and 1890s.This period of prolonged drought in northeastern China coincided with the combined impacts of climatic factors and human influences,contributing to the fall of the Qing Dynasty.Analysis of periodicity and anomalies in sea surface temperatures indicate a strong association between wet and dry cycles and El Niño-Southern Oscillations.Our findings offer insights into long-term dry and wet fluctuations at the desert margins in northern China and elucidate the relationship between drought and the dynamics of civilizations.They also highlight the potential impact of extremes in climate on modern society,especially under the four projected shared socioeconomic pathways climatic scenarios,which predict worsening droughts in northern China.
基金the partial financial support of this study from CONACYT (Grant 179110)
文摘Aluminum alloy samples, 6061-T6 and 2219-T42, were exposed to Caribbean seawater for 90 d. The fluctuations of open circuit potential, considered as electrochemical noise (EN), were used to characterize and compare initial pitting events, which appeared on their surfaces. EN analysis was carried out using the power spectral density (PSD) vs frequency. The decrease of the β exponent in PSD graphs indicated a release of spontaneous energy with the progress of pit formation in seawater. The fluctuations were associated with the breakdown and formation of new corrosion layers. The values of β exponent in PSD graphs suggest that corrosion process of AA2219-T42 alloy occurs as a persistent non-stationary process, the dynamics of which is controlled by fractional Brownian motion (fBm), while on AA6061-T6 alloy the corrosion process was dominated by stationary and weakly persistent features, with the contribution of fractional Gaussian noise (fGn). After the exposure in seawater, SEM-EDX analysis revealed insoluble intermetallic particles on the alloys, rich in Cu or Fe and irregularly distributed. The preferential dissolution of Mg and Al occurs from the S-phase (Al2CuMg) of AA2219-T42 alloy.
基金supported by the Project No.CB/2012/178748 CONACYT/México
文摘Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.
基金the financial support from CONACYT-México(No.248378)CONACYT-México for the fellowship 427467partially supported by the project "Fortalecimiento e internacionalización del doctorado en ciencias(Materiales Poliméricos)del CICY" FOMIX YUC 2014-C17-247046
文摘Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic acid(TERT), with 4,4′-(hexafluoroisopropylidene)dianiline(HFA) or 2,3,5,6-tetramethyl-1,4-phenylenediamine(Durene) by direct polycondensation. The structures of the obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1 H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 and 1.60 nm, respectively. Moreover, they presented good thermal stability up to300 °C. Young's moduli of the co-polyamide films were between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films were amorphous due to the incorporation of both bulky pendant groups, tert-butyl and dibenzobarrelene. The combination of bulky pendant groups provided intrinsically transparent co-polyamide films with a transmittance higher than 88% in the range of 400-780 nm.Due to these outstanding film and optical properties, they are suggested to be flexible substrates in applications for solar cell and other portable electronic devices.
文摘The extraction of anthocyanins present in the skin of the dragon fruit was performed using trifluoroacetic acid (TFA) plus a mixture of methanol, acetic acid and water;the anthocyanins were then purified with a LC-18 cartridge, using methanol acidified with TFA as eluent, reaching concentrations of 44.3865 ± 1.3125 mg/100g of sample. The extracts were put through stability tests under different storage conditions, modifying the pH of the extracts (pH of 1, 4 and 6), the temperature (4℃, 25℃ and 68℃) and the absence and presence of light for a time period of 4 days;the tests indiated that anthocyanins remain more stable at a temperature of 4℃?with a pH of 4 in the absence of light, retaining up to 80% of the pigment. Three anthocyanins were partially identified in the extracts by high performance liquid chromatography (HPLC);they were: cyanidin 3-O-glucoside, cyanidin 3,5 O-glucoside and pelargonidin 3,5 O-glucoside.
文摘The removal efficiency of Cu and Zn from swine wastewater was evaluated as effected by three variables: the hydraulic retention time (HRT) (24, 48, 72 and 96 hours), two different plant species (Typha domingensis Pers. and Eleocharis cellulosa) and two different sizes of filter media (5 and 15 mm) using a horizontal sub-surface flow constructed wetland. From the results, a significant difference was observed in the removal efficiency of Cu and Zn with respect to different hydraulic retention times. The best results were obtained in the HRT of 96 hours for Zn where 96% removal of Zn with Typha domingensis Pers. specie with gravel of 15 mm (experimental unit 6) was achieved. For Cu, at 72 hours of HRT, the efficiency was nearly 100% in five of the six study units (1, 2, 3, 5 and 6). In contrast, in experimental unit 4 with gravel of 15 mm and without plants, only 86% Cu removal was achieved.
基金the CDCHTA of the University of Los Andes for providing financial support through several approved projectsthe National Fund for Science, Technology and Innovation (FONACIT) of Venezuelan Ministry of Science and Technology for providing financial support, SPE 112–370 and Project G-2005000641
文摘The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.
基金financed by the FOMIX-Yucatán 2008-108160,CONACYT LAB-2009-01-123913,292692,294643,188345,and 204822 projectsthe financial support received from CONACYT。
文摘The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this reactivity.In this work,we present Mg(OH)_(2) and TiO_(2)barrier coatings to reduce the degradation of magnesium alloy(Mg-Ca-Zn)surfaces.These coatings were deposited by the anodization method and the spin-coating technique,respectively.The anodized layer was coated with TiO_(2)generated from the hydrolysis of 3%weight of TTIP(Ti[OCH(CH_(3))_(2)]_(4),Titanium(IV)isopropoxide)in 2-Propanol deposited by the spin-coating method.Studying the degradation in Ringer’s solution by electrochemical impedance spectroscopy and OCP revealed a 98%reduction in pittings in uncoated samples after 14 days of immersion.The p H measurements revealed that the TiO_(2)coating reduced the alkalization of the physiological environment,keeping the pH at 6.0 values.In vitro studies of two types of bacteria(E.coli and S.aureus)exhibited zones of inhibition in the agar and activity bactericidal(kill time test).The mechanisms behind the improved degradation resistance and enhanced antibacterial activity are presented and discussed here.Surface modification with Mg(OH)_(2)/TiO_(2)coatings is a promising strategy to control the biodegradation of magnesium implants for bone regeneration.
文摘Respiratory disorders during sleep have as a general characteristic the alteration of the respiratory cycle while sleeping. The most outstanding characteristic of Obstructive Sleep Apnea Syndrome (OSA) is the partial (hypopnea) or total (apnea) obstruction of the upper airway that occurs repeatedly during sleep. The OSA is global public health issue. When it is not treated, OSA represents a cost two or three times higher of the institutional resources for health. Studies conducted in different countries indicate that the prevalence of the OSA goes from 2% to 10% in general population. The OSA is a serious sleep disorder that has negative implications on multiple systems of the organism. It is associated with hypertension, diabetes and the metabolic syndrome. When OSA coexists with a heart disease or ischemic heart disease, it significantly raises the probability of a heart failure. The use of Continuous Positive Airway Pressure (CPAP) is so far the most effective method for OSA treatment. Intervention at different levels (physiological, educational and psychological intervention) appears to be important in adherence to CPAP treatment.
文摘Urolithiasis (UL) is an endemic disease in Southeastern, Mexico. In order to evaluate the association of I550V polymorphism in the hNaDC-1 gene with risk for hypocitraturia and/or for UL;139 adults with UL and 132 adults without UL, were included under a case-control association study. Citrate levels in 24-h urine were quantified (citraturia). The polymorphism I550V-hNaDC-1 was determined by PCR-RFLP. Statistical analysis was performed using the STATA10.2 software. Comparison of genotype and allele frequencies between subjects with and without UL showed significant differences for genotype bb (OR = 2.34, CI: 1.19-4.59, p = 0.01) and for allele b (OR = 1.62, CI: 1.15-2.28, p = 0.005), suggesting an association with the risk for UL. Comparison of genotype and allele frequencies between subjects with hypocitraturia and subjects with normocitraturia, did not show any significant difference (p > 0.05), suggesting that this polymorphism is not associated with the risk of hypocitraturia. Interestingly, the risk for UL was increased due to an additive effect of hypocitraturia with the genotype bb (OR = 6.6, CI: 2.38-18.28, p = 0.0002) or with the allele b (OR: 4.2, CI = 2.52-6.97,
文摘Transcranial direct current stimulation(tDCS)has been reportedly beneficial for different neurodegenerative disorders.tDCS has been reported as a potential adjunctive or alternative treatment for auditory verbal hallucination(AVH).This study aims to review the effects of tDCS on AVH in patients with schizophrenia through combining the evidence from randomized clinical trials(RCTs).The databases of PsycINFO(2000–2019),PubMed(2000–2019),EMBASE(2000–2019),CINAHL(2000–2019),Web of Science(2000–2019),and Scopus(2000–2019)were systematically searched.The clinical trials with RCT design were selected for final analysis.A total of nine RCTs were eligible and included in the review.Nine RCTs were included in the final analysis.Among them,six RCTs reported a significant reduction of AVH after repeated sessions of tDCS,whereas three RCTs did not show any advantage of active tDCS over sham tDCS.The current studies showed an overall decrease of approximately 28%of AVH after active tDCS and 10%after sham tDCS.The tDCS protocols targeting the sensorimotor frontal-parietal network showed greater treatment effects compared with the protocols targeting other regions.In this regard,cathodal tDCS over the left temporoparietal area showed inhibitory effects on AVHs.The most effective tDCS protocol on AVHs was twice-daily sessions(2 mA,20-minute duration)over 5 consecutive days(10 sessions)with the anode over the left dorsolateral prefrontal cortex and the cathode over the left temporal area.Some patient-specific and diseasespecific factors such as young age,nonsmoking status,and higher frequencies of AVHs seemed to be the predictors of treatment response.Taken together,the results of tDCS as an alternative treatment option for AVH show controversy among current literatures,since not all studies were positive.However,the studies targeting the same site of the brain showed that the tDCS could be a promising treatment option to reduce AVH.Further RCTs,with larger sample sizes,should be conducted to reach a conclusion on the efficacy of tDCS for AVH and to develop an effective therapeutic protocol for clinical setting.
文摘The browning of fruits can be considered as an enzymatic oxidation which is believed to be one of the main causes of quality loss during post-harvest handling. The enzymes responsible for this are the oxidoreductases;the polyphenol oxidase (PPO) (monophenol, o-diphenol, oxygen oxidoreductase;EC 1.14.18.1) belongs to this group. This enzyme, which is found in the sapodilla plum (Achras sapota), was purified using a phenylsepharose and a SephacrylS-200 columns. The molecular weight of the purified enzyme was estimated to be about 66 kDa by gel filtration and 29 kDa by SDS-PAGE. A single protein band was found using the latter system (SDS-PAGE), which shows that the PPO of the pulp of the sapodilla plum may be composed of two protein subunits with similar molecular weight. The optimum pH was 7.0 and the optimum temperature 60℃. The most effective inhibitors tested were ascorbic acid, sodium metabisulfite and acetic acid.
文摘The hydrolysis of velvet bean (Mucuna pruriens) protein in the presence of Alcalase?-Flavourzyme? and Pepsin-Pancreatin was investigated. The results showed that Alcalase?-Flavourzyme? (29.08%) sequential system catalyzed the hydrolysis most efficiently that Pepsin-Pancreatin (24.78%). In addition, the higher ACE-I inhibitory activity was achieved with the sequential system Alcalase?-Flavourzyme? (33.13%). Furthermore, the concentration of peptides employing an ultrafiltration (UF) system or their purification by gel filtration chromatography showed that the oligomeric peptides with lower molecular weight registered the highest ACE-I inhibitory activity. It has been demonstrated that Mucuna pruriens protein hydrolysates could serve as a source of peptides with ACE inhibitory activity and this activity can be attributed mainly to the mixture of short peptides in the hydrolysate.
文摘To describe the annual cycle of Sargassum horneri in Mexican waters, we selected two sites differing in their degree of wave exposure and sediment type: Rincón de Ballenas (RB), and Rancho Packard (RP). From June 2009 to April 2010 we followed the seasonal changes in S. horneri density and biomass along two intertidal transects per site. The effects of this non-indigenous species on the local macroalgae community were assessed by comparing their species composition, density, biomass, species richness, and diversity index in quadrats with and without S. horneri. There were significant differences in S. horneri density and biomass between sites (P < 0.001). At RB the invasive alga density average was 2 ± 0.94 individual m-2, with a mean biomass of 4 ± 0.95 g DW m-2. At RP, S. horneri density average was 10 ± 0.96 individual m-2, and mean biomass of 102 ± 0.97 g DW m-2. At RB, the invasive alga promoted a significant reduction in the four selected structural variables, and the corticated macrophytes and the foliose functional forms were severely reduced. At RP, there were only marginally significant effects (P = 0.06) of S. horneri presence on the local macroalgae community, and higher density, biomass, and diversity values were found when S. horneri was present. Most of the functional forms were found, even if the invasive alga was present. At both locations, the highest biomass corresponded to the articulated calcareous functional form. These contrasting results could be due to the fact that the native macroalgae community has already been altered by the early invasion of S. muticum, with the most resilient species and functional forms remaining in place. One of the most important changes we noticed is the severe reduction of the canopy forming species at both sites.
文摘A physicochemical characterization of oil from chia seeds was carried out. Proximate composition analysis showed that fat and fiber were the principal components in the raw chia flour. Physical characterization showed that chia oil has a relative density from 0.9241, a refraction index of 1.4761 and a color with more yellow than red units. Chemical characterization showed that chia oil registered an acidity index of 2.053 mg KOH/g oil, a saponification index of 222.66 mg KOH/g oil, a content of unsaponifiable matter of 0.087%, an Iodine index of 193.45 g I/100 g oil and a peroxide index of 17.5 meq O2/kg oil. Chia oil showed a higher content of α and β linolenic and palmitic acids. Chia oil is the vegetable source with the highest content of essential fatty acids.
