To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,lig...To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.展开更多
Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with t...Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with triple bandnotched characteristics is presented. The proposed antenna consists of a square patch with four truncated corners and a partial ground plane with a rectangular slit. The operation bandwidth of the designed antenna is from 2.66 GHz to more than 13.5 GHz. Band-notched characteristics of antenna to reject the frequency band of 3.18 - 3.59 GHz and 4.70 - 5.88 GHz, is realized by inserting two C-shaped slots in the patch, the third band of 9.54 - 12.22 GHz is achieved by slottype capacitively-loaded loop (CLL) inserted in the patch near the feed line. Details of the proposed antenna design and simulated results are presented and discussed.展开更多
A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficie...A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficients, drag coefficients, and surface pressure coefficients are discussed with the results of wind tunnel experiments using the HL-20 lift body and the NASA hypersonic aircraft STS Columbia OV-102 as research subjects. Finally, the results of the experimental and wind tunnel studies of the aerodynamic characteristics of the HL-20 lift body at an altitude of 65 km and Mach numbers of 6 and 10 Ma are discussed. The maximum error in the aerodynamic characteristics at 6 Ma does not exceed 3%, consistent with the results. The maximum error at 10 Ma occurs in the 11° - 14° angle of attack and does not exceed 10%, which is still within the error tolerance. The STS results for NASA’s hypersonic aircraft were also tested using this procedure. Experimental aerodynamic data for the Colombian OV-102 aircraft. The results show that the program takes only 10 minutes to calculate the results, with no more than 2% error from the wind tunnel experimental results.展开更多
Business correspondence are the indispensable tool in the practical process of business communication and interchange.Especially,as the communicated body of information,their language possesses specific characteristic...Business correspondence are the indispensable tool in the practical process of business communication and interchange.Especially,as the communicated body of information,their language possesses specific characteristics.Rooted from the "Politeness Principle" and the "Cooperative Principle",the most distinctive epitome of it is the seven "C" principles.Based on the discussion of the seven "C" principles,this paper devotes itself to the analyses of the contradictory characteristics which occur frequently in the concrete business contexts,and then to examine the causes of these features.Ultimately,it will suggest more flexible and more widened perspective towards the creation of business correspondence and the language applied in them.展开更多
[Objective] To study the germination characteristics and secondary metabolism of Scutellaria baicalensis Georgi seeds under different temperatures.[Method]The activities of superoxide dismutase(SOD)and peroxidase(...[Objective] To study the germination characteristics and secondary metabolism of Scutellaria baicalensis Georgi seeds under different temperatures.[Method]The activities of superoxide dismutase(SOD)and peroxidase(POD)were determined with lactoflavine-NBT method and guaiacol-colorimetry assay,respectively.The catalase(CAT),ascorbate peroxidase(APX),phenylalanine ammonia-lyase(PAL)and cinnamic acid 4-Hydroxylase(C4H)were determined with ultraviolet spectrophotometry.The secondary metabolites were detected by High Performance Liquid Chromatography(HPLC).[Result]The germination percentage,germination potentiality and germination index were seriously affected by low or high temperature.The proper germination temperature was 20-25 ℃.The activities of SOD,POD and CAT were significantly decreased as comparison to suitable temperature.The activities of PAL and C4H were also significantly decreased as comparision to suitable temperature which was accordance to the secondary metabolites.There was a positive correlation between the flavonoids content and the PAL and C4H activity(r=0.956,r=0.951,P0.05).[Conclusion]The quality of the skullcaps could be improved by improving the activity of PAL and C4H.The proper temperature for the seed germination and the formation of secondary metabolites was 20 ℃.展开更多
Objective: To compare the clinical characteristics and prognosis between hepatitis virus-related hepatocellular carcinoma(viral HCC) and non-B, non-C HCC(NBC-HCC) among Uyghur patients in Xinjiang province, China...Objective: To compare the clinical characteristics and prognosis between hepatitis virus-related hepatocellular carcinoma(viral HCC) and non-B, non-C HCC(NBC-HCC) among Uyghur patients in Xinjiang province, China. Methods: Between 01/01/2000 and 31/12/2012, 319 Uyghur HCC patients were treated at the Cancer Centre of The First Affiliated Hospital of Xinjiang Medical University. The data for the patients were obtained from a retrospective review of the patients' medical records. A total of 18 patients were excluded from the study because of incomplete information. The patients were classified into two groups: viral HCC and NBC-HCC. The clinical characteristics and prognostic factors were statistically analysed.Results: For all 301 patients, gender(P=0.000), area of residence(P=0.002), diabetes mellitus(P=0.009), BMI(P=0.000), cirrhosis(P=0.000), tumour stage(P=0.004), Child-Pugh class(P=0.000), the TBIL level(P=0.000), and the alpha-fetoprotein(AFP) level(P=0.000) were significantly different between the NBC-HCC and viral HCC groups. The NBC-HCC patients tended to be diagnosed at advanced stages; however, the NBC-HCC patients exhibited lower Child-Pugh scores than the viral HCC patients. In all patients examined, the 0.5-, 1-, 3- and 5-year overall survival(OS) rates were 35.6%, 20.3%, 12.6% and 4.5%, respectively. No significant difference in OS was observed between the two groups(P=0.124). Cox multivariate analysis revealed that age(RR =1.539, P=0.001), TNM stage(RR =12.708, P=0.000), portal vein tumour thrombus(PVTT)(RR =2.003, P=0.000), Child-Pugh class(RR =1.715, P=0.000), and TACE + radiotherapy/RFA(RR =0.567, P=0.000) were significant independent prognostic factors for HCC patients. Conclusions: The clinical characteristics differ between Uyghur patients with NBC-HCC and viral HCC. HCC in the Xinjiang region displays specific regional characteristics. Age, TNM stage, PVTT, Child-Pugh class and TACE + radiotherapy/RFA are significant risk factors that influence patient survival.展开更多
A 4H-silicon carbide metal-insulator-semiconductor structure with ultra-thin Al2O3 as the gate dielectric, deposited by atomic layer deposition on tile epitaxial layer of a 4H-SiC (0001) 80N-/N+ substrate, has been...A 4H-silicon carbide metal-insulator-semiconductor structure with ultra-thin Al2O3 as the gate dielectric, deposited by atomic layer deposition on tile epitaxial layer of a 4H-SiC (0001) 80N-/N+ substrate, has been fabricated. The experimental results indicate that the prepared ultra-thin Al2O3 gate dielectric exhibits good physical and electrical characteristics, including a high breakdown electrical field of 25 MV/cm, excellent interface properties (1 × 10^14 cm^-2) and low gate-leakage current (IG = 1 × 10^-3 A/cm 2@Eox = 8 MV/cm). Analysis of the current conduction mecha- nism on the deposited Al2O3 gate dielectric was also systematically performed. The confirmed conduction mechanisms consisted of Fowler-Nordheim (FN) tuaneling, the Frenkel-Poole mechanism, direct tunneling and Schottky emission, and the dominant current conduction mechanism depends on the applied electrical field. When the gate leakage current mechanism is dominated by FN tunneling, the barrier height of SiC/Al2O3 is 1.4 eV, which can meet the requirements of silicon carbide metal-insulator-semiconductor transistor devices.展开更多
[Objectives]This study was conducted to study the Germination characteristics and secondary metabolism regulation of Scutellaria baicalensis Georgi under osmotic stress.[Methods]The activity of praline,soluble sugar a...[Objectives]This study was conducted to study the Germination characteristics and secondary metabolism regulation of Scutellaria baicalensis Georgi under osmotic stress.[Methods]The activity of praline,soluble sugar and protein was detected with ultraviolet spectrophotometry.The activity of phenylalanine ammonia-lyase(PAL)and cinnamic acid 4-hydroxylase(C_4H)was determined with ultraviolet spectrophotometry.The secondary metabolites were detected by high performance liquid chromatography(HPLC).[Results]The germination percentage,germination potentiality and germination index decreased at first and increased subsequently along with the enhancement of PEG concentration.The praline content,the soluble sugar content and the soluble protein content in S.baicalensis seedlings increased along with the enhancement of PEG concentration and the differences from the CK were significant(P<0.05).The PAL and C_4H in S.baicalensis seedlings decreased after osmotic stress and the differences from the CK were significant(P<0.05).The results indicate that,the scutellarin,baicalin,wogonoside,baicalein,wogonin and oroxylinA contents decreased after osmotic stress and the differences from the CK were significant(P<0.05).[Conclusions]The quality of the skullcaps could be improved by improving the activity of PAL and C_4H.展开更多
A study of flow characteristics of blast furnace slag helps determine its softening and flow (liquid-mobility) temperatures. The slag with a narrow difference between the two temperatures is termed a “Short Slag”. I...A study of flow characteristics of blast furnace slag helps determine its softening and flow (liquid-mobility) temperatures. The slag with a narrow difference between the two temperatures is termed a “Short Slag”. Its formation ensures higher rates of slag-metal reactions with the trickle of the slag soon after its formation exposing fresh mass for faster reactions, the trickling slag, creating fresh interfaces facilitating slag-metal exchanges. In the present work, a novel technique is adopted to determine the flow characteristics of blast furnace slag obtained from different industrial blast furnaces. It is seen that the results so obtained agree very closely with the values obtained from adopting conventional methods of determining the liquidus temperature using “slag atlas”. It is observed that under the range of compositions studied a high C/S ratio combined with a high MgO content in the slag is beneficial to the B.F. process as it renders a “short slag”.展开更多
The fluorescent principle used for measuring alga characteristic parameters and the optimum structure design of the instrument are discussed. The fluorescent spectrum of Chla/c and the time-resolved different spectrum...The fluorescent principle used for measuring alga characteristic parameters and the optimum structure design of the instrument are discussed. The fluorescent spectrum of Chla/c and the time-resolved different spectrum ΔA(λ,t) are given. The research provides an effective method for considering the density and the classification of algae, which will be helpful to monitor sea pollution.展开更多
AIM: To describe a population of outpatients in China infected by hepatitis B virus (HBV) and/or hepatitis C virus (HCV), and assess their current management status. METHODS: A multicenter, cross-sectional study of HB...AIM: To describe a population of outpatients in China infected by hepatitis B virus (HBV) and/or hepatitis C virus (HCV), and assess their current management status. METHODS: A multicenter, cross-sectional study of HBV- and/or HCV-infected patients was conducted from August to November, 2011 in western China. Patients >= 18 years of age with HBV and/or HCV infections who visited outpatient departments at 10 hospitals were evaluated, whether treated or not. Data were collected on the day of visit from medical records and patient interviews. RESULTS: A total 4010 outpatients were analyzed, including 2562 HBV- infected and 1406 HCV-infected and 42 HBV/HCV co-infected patients. The median duration of documented infection was 7.5 years in HBV- infected and 1.8 years in HCV-infected patients. Cirrhosis was the most frequent hepatic complication (12.2%), appearing in one-third of patients within 3 years prior to or at diagnosis. The HCV genotype was determined in only 10% of HCV-infected patients. Biopsy data were only available for 54 patients (1.3%). Antiviral medications had been received by 58.2% of patients with HBV infection and 66.6% with HCV infection. Nucleos(t) ide analogs were the major antiviral medications prescribed for HBV- infected patients (most commonly adefovir dipivoxil and lamivudine). Ribavirin + pegylated interferon was prescribed for two-thirds of HCV-infected patients. In the previous 12 mo, around one-fifth patients had been hospitalized due to HBV or HCV infection. CONCLUSION: This observational, real-life study has identified some gaps between clinical practice and guideline recommendations in China. To achieve better health outcomes, several improvements, such as disease monitoring and optimizing antiviral regimens, should be made to improve disease management. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.展开更多
In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermitt...In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.展开更多
As an important part of gas hydrates, light hydrocarbons (LHs), especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received ...As an important part of gas hydrates, light hydrocarbons (LHs), especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received much attention from organic geochemists and petroleum geologists.展开更多
A 1064 nm Nd:YAG laser was used to of the spectral lines measured from the laserablated ablate fly ash samples. The characteristics fly ash plasmas are presented with special attention to atomic and molecular carbon ...A 1064 nm Nd:YAG laser was used to of the spectral lines measured from the laserablated ablate fly ash samples. The characteristics fly ash plasmas are presented with special attention to atomic and molecular carbon emission. It is shown that the intensity of the atomic line C I 192.9 nm is weak and the shot-to-shot intensity is fluctuant. The carbon atomic line C I 247.7 nm is relatively intensive and stable, however it is seriously interfered with by Fe I 247.8 nm. The intensity of the CN molecular line is close to that of C I 247.7 nm and the CN line is stable and less interfered with. The comparison of molecular CN emission under different conditions (air, Ar and N2) shows that the CN lines detected from the plasmas formed in an atmospheric environment are correlated with the reaction of carbon atoms in the plasma with the nitrogen in air, which indicates that the CN line is also important in pulsed laser ablation fly ash plasmas and this information can be incorporated in the detection of unburned carbon content in fly ash. Finally, a calibration curve is established with a correlation coefficient R2 of 0.999, using C I 247.7 nm and the CN molecular line as associated variables. In addition, accuracy is improved to a certain extent.展开更多
[Objectives]This study aimed to establish a quality evaluation method for Herba Cistanche based on the HPLC characteristic chromatograms of the phenylethanoid glycosides and iridoid glycosides,and compare the HPLC cha...[Objectives]This study aimed to establish a quality evaluation method for Herba Cistanche based on the HPLC characteristic chromatograms of the phenylethanoid glycosides and iridoid glycosides,and compare the HPLC characteristic chromatograms of different origins of Herba Cistanche.[Methods]The chromatographic conditions used were as follows:column,Agilent ZORBAX Eclipse Plus C18 column(4.6 mm×250 mm,5μm);gradient elution,acetonitrile-0.1%phosphoric acid aqueous solution;flow rate,1.0 mL/min;detection wavelength,240 nm;column temperature,30℃.[Results]Cistanche tubulosa(Schenk)Wight showed 9 characteristic peaks,Cistanche deserticola Y.C.Ma showed 10 characteristic peaks,Cistanche salsa(C.A.Mey.)G.Beck showed 7 characteristic peaks,and Cistanche sinensis G.Beck showed 4 characteristic peaks.Peak 6 was echinacoside,peak 7 was verbascoside,peak 8 was tubuloside A,peak 9 was isoacteoside and peak 10 was cistanoside A.The characteristic chromatograms of the four different origins of Herba Cistanche were significantly different.[Conclusions]This characteristic chromatogram method has good reproducibility and can be used to distinguish 4 different origins of Herba Cistanche,C.deserticola Y.C.Ma,C.tubulosa(Schenk)Wight,C.sinensis G.Beck and C.salsa(C.A.Mey.)G.Beck.展开更多
The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance ...The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp...展开更多
Recent investigations on pomegranate products have significantly increased and successfully drawn consumers’ attention to nutritional and medicinal values, promoting the pomegranate industry’s development worldwide....Recent investigations on pomegranate products have significantly increased and successfully drawn consumers’ attention to nutritional and medicinal values, promoting the pomegranate industry’s development worldwide. However, little information on pomegranates grown in China is available. Morphological and chemical characterizations of fruits and arils from 20 pomegranate cultivars in six regions of China were investigated. Combined with overall scores by principal component analysis, ‘Yushiliu No. 1’, ‘Taishanhong No. 2’, ‘Tunisia’ and ‘Mollar’ were promising cultivars, and Chinese researchers bred the first two. It was surprising that ‘Mollar’ had bigger fruit size and more aril moisture grown in China than in Spain. Cultivars with higher anthocyanin content in arils were ‘Turkey’, ‘Moyu’ and ‘Red Angel’, which might be used as the source of natural red food colourants. While red husk ‘Hongruyi’ and ‘Hongshuangxi’ with higher vitamin C, aril moisture and lower titratable acid in arils, might also be promising cultivars for further various utilization. Furthermore, the comparison of ‘Tunisia’ fruits from four regions revealed that cultivation locations had more influence on fruit traits than genotypes. Maturity index classification was established for Chinese pomegranate cultivars. Therefore, the results would provide a valuable guide for agricultural cultivation, industrial utilization, and breeding.展开更多
This paper has researched the insulation characteristics of 10% c-C4F8/N2/CO2 mixtures under lightning impulse voltage by experiment. It is shown that the positive and negative lightning impulse breakdown voltages of ...This paper has researched the insulation characteristics of 10% c-C4F8/N2/CO2 mixtures under lightning impulse voltage by experiment. It is shown that the positive and negative lightning impulse breakdown voltages of 10%c-C4F8/N2/CO2 gas mixtures rise linearly as the electrode gap distance and gas pressure increase and under the same conditions, the positive lightning impulse breakdown voltage of the gas mixtures is always higher than the negative lightning impulse breakdown voltage. As the gas mixtures have a little higher liquefied temperature than SF6 and the comprehensive GWP is about 5% of SF6, and the positive and negative lightning impulse breakdown voltages can both reach 60% of SF6, 10%c-C4F8/N2/CO2 gas mixtures can be applied as insulation gas in electrical equipment such as C-GIS, GIT, GIL and so on.展开更多
基金This study was supported by the National Natural Science Foundation of China(31960306).
文摘To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.
文摘Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with triple bandnotched characteristics is presented. The proposed antenna consists of a square patch with four truncated corners and a partial ground plane with a rectangular slit. The operation bandwidth of the designed antenna is from 2.66 GHz to more than 13.5 GHz. Band-notched characteristics of antenna to reject the frequency band of 3.18 - 3.59 GHz and 4.70 - 5.88 GHz, is realized by inserting two C-shaped slots in the patch, the third band of 9.54 - 12.22 GHz is achieved by slottype capacitively-loaded loop (CLL) inserted in the patch near the feed line. Details of the proposed antenna design and simulated results are presented and discussed.
文摘A program for calculating the aerodynamic properties of hypersonic vehicles based on the surface element method was developed using the general-purpose programming language C++. The calculated values of lift coefficients, drag coefficients, and surface pressure coefficients are discussed with the results of wind tunnel experiments using the HL-20 lift body and the NASA hypersonic aircraft STS Columbia OV-102 as research subjects. Finally, the results of the experimental and wind tunnel studies of the aerodynamic characteristics of the HL-20 lift body at an altitude of 65 km and Mach numbers of 6 and 10 Ma are discussed. The maximum error in the aerodynamic characteristics at 6 Ma does not exceed 3%, consistent with the results. The maximum error at 10 Ma occurs in the 11° - 14° angle of attack and does not exceed 10%, which is still within the error tolerance. The STS results for NASA’s hypersonic aircraft were also tested using this procedure. Experimental aerodynamic data for the Colombian OV-102 aircraft. The results show that the program takes only 10 minutes to calculate the results, with no more than 2% error from the wind tunnel experimental results.
文摘Business correspondence are the indispensable tool in the practical process of business communication and interchange.Especially,as the communicated body of information,their language possesses specific characteristics.Rooted from the "Politeness Principle" and the "Cooperative Principle",the most distinctive epitome of it is the seven "C" principles.Based on the discussion of the seven "C" principles,this paper devotes itself to the analyses of the contradictory characteristics which occur frequently in the concrete business contexts,and then to examine the causes of these features.Ultimately,it will suggest more flexible and more widened perspective towards the creation of business correspondence and the language applied in them.
基金Supported by Technology Development Plan of Shandong Province(2008GG2NS02022)Agricultural Seed Project in Shandong Province(2009LZ01-03)National Key Basic Research Program(2007CB512601)~~
文摘[Objective] To study the germination characteristics and secondary metabolism of Scutellaria baicalensis Georgi seeds under different temperatures.[Method]The activities of superoxide dismutase(SOD)and peroxidase(POD)were determined with lactoflavine-NBT method and guaiacol-colorimetry assay,respectively.The catalase(CAT),ascorbate peroxidase(APX),phenylalanine ammonia-lyase(PAL)and cinnamic acid 4-Hydroxylase(C4H)were determined with ultraviolet spectrophotometry.The secondary metabolites were detected by High Performance Liquid Chromatography(HPLC).[Result]The germination percentage,germination potentiality and germination index were seriously affected by low or high temperature.The proper germination temperature was 20-25 ℃.The activities of SOD,POD and CAT were significantly decreased as comparison to suitable temperature.The activities of PAL and C4H were also significantly decreased as comparision to suitable temperature which was accordance to the secondary metabolites.There was a positive correlation between the flavonoids content and the PAL and C4H activity(r=0.956,r=0.951,P0.05).[Conclusion]The quality of the skullcaps could be improved by improving the activity of PAL and C4H.The proper temperature for the seed germination and the formation of secondary metabolites was 20 ℃.
基金supported by a grant from the Urumqi Science and Technology Project Foundation of China(No.H111313001)
文摘Objective: To compare the clinical characteristics and prognosis between hepatitis virus-related hepatocellular carcinoma(viral HCC) and non-B, non-C HCC(NBC-HCC) among Uyghur patients in Xinjiang province, China. Methods: Between 01/01/2000 and 31/12/2012, 319 Uyghur HCC patients were treated at the Cancer Centre of The First Affiliated Hospital of Xinjiang Medical University. The data for the patients were obtained from a retrospective review of the patients' medical records. A total of 18 patients were excluded from the study because of incomplete information. The patients were classified into two groups: viral HCC and NBC-HCC. The clinical characteristics and prognostic factors were statistically analysed.Results: For all 301 patients, gender(P=0.000), area of residence(P=0.002), diabetes mellitus(P=0.009), BMI(P=0.000), cirrhosis(P=0.000), tumour stage(P=0.004), Child-Pugh class(P=0.000), the TBIL level(P=0.000), and the alpha-fetoprotein(AFP) level(P=0.000) were significantly different between the NBC-HCC and viral HCC groups. The NBC-HCC patients tended to be diagnosed at advanced stages; however, the NBC-HCC patients exhibited lower Child-Pugh scores than the viral HCC patients. In all patients examined, the 0.5-, 1-, 3- and 5-year overall survival(OS) rates were 35.6%, 20.3%, 12.6% and 4.5%, respectively. No significant difference in OS was observed between the two groups(P=0.124). Cox multivariate analysis revealed that age(RR =1.539, P=0.001), TNM stage(RR =12.708, P=0.000), portal vein tumour thrombus(PVTT)(RR =2.003, P=0.000), Child-Pugh class(RR =1.715, P=0.000), and TACE + radiotherapy/RFA(RR =0.567, P=0.000) were significant independent prognostic factors for HCC patients. Conclusions: The clinical characteristics differ between Uyghur patients with NBC-HCC and viral HCC. HCC in the Xinjiang region displays specific regional characteristics. Age, TNM stage, PVTT, Child-Pugh class and TACE + radiotherapy/RFA are significant risk factors that influence patient survival.
基金supported by the 2010 School Fundamental Scientific Research Fund of Xidian University (Grant No. K50510250008)
文摘A 4H-silicon carbide metal-insulator-semiconductor structure with ultra-thin Al2O3 as the gate dielectric, deposited by atomic layer deposition on tile epitaxial layer of a 4H-SiC (0001) 80N-/N+ substrate, has been fabricated. The experimental results indicate that the prepared ultra-thin Al2O3 gate dielectric exhibits good physical and electrical characteristics, including a high breakdown electrical field of 25 MV/cm, excellent interface properties (1 × 10^14 cm^-2) and low gate-leakage current (IG = 1 × 10^-3 A/cm 2@Eox = 8 MV/cm). Analysis of the current conduction mecha- nism on the deposited Al2O3 gate dielectric was also systematically performed. The confirmed conduction mechanisms consisted of Fowler-Nordheim (FN) tuaneling, the Frenkel-Poole mechanism, direct tunneling and Schottky emission, and the dominant current conduction mechanism depends on the applied electrical field. When the gate leakage current mechanism is dominated by FN tunneling, the barrier height of SiC/Al2O3 is 1.4 eV, which can meet the requirements of silicon carbide metal-insulator-semiconductor transistor devices.
基金Supported by 2017 Traditional Chinese Medicine Public Health Service Specific Grant(CS[2017]66)Shandong Traditional Chinese Medicine Science and Technology Development Program(2017-522)
文摘[Objectives]This study was conducted to study the Germination characteristics and secondary metabolism regulation of Scutellaria baicalensis Georgi under osmotic stress.[Methods]The activity of praline,soluble sugar and protein was detected with ultraviolet spectrophotometry.The activity of phenylalanine ammonia-lyase(PAL)and cinnamic acid 4-hydroxylase(C_4H)was determined with ultraviolet spectrophotometry.The secondary metabolites were detected by high performance liquid chromatography(HPLC).[Results]The germination percentage,germination potentiality and germination index decreased at first and increased subsequently along with the enhancement of PEG concentration.The praline content,the soluble sugar content and the soluble protein content in S.baicalensis seedlings increased along with the enhancement of PEG concentration and the differences from the CK were significant(P<0.05).The PAL and C_4H in S.baicalensis seedlings decreased after osmotic stress and the differences from the CK were significant(P<0.05).The results indicate that,the scutellarin,baicalin,wogonoside,baicalein,wogonin and oroxylinA contents decreased after osmotic stress and the differences from the CK were significant(P<0.05).[Conclusions]The quality of the skullcaps could be improved by improving the activity of PAL and C_4H.
文摘A study of flow characteristics of blast furnace slag helps determine its softening and flow (liquid-mobility) temperatures. The slag with a narrow difference between the two temperatures is termed a “Short Slag”. Its formation ensures higher rates of slag-metal reactions with the trickle of the slag soon after its formation exposing fresh mass for faster reactions, the trickling slag, creating fresh interfaces facilitating slag-metal exchanges. In the present work, a novel technique is adopted to determine the flow characteristics of blast furnace slag obtained from different industrial blast furnaces. It is seen that the results so obtained agree very closely with the values obtained from adopting conventional methods of determining the liquidus temperature using “slag atlas”. It is observed that under the range of compositions studied a high C/S ratio combined with a high MgO content in the slag is beneficial to the B.F. process as it renders a “short slag”.
文摘The fluorescent principle used for measuring alga characteristic parameters and the optimum structure design of the instrument are discussed. The fluorescent spectrum of Chla/c and the time-resolved different spectrum ΔA(λ,t) are given. The research provides an effective method for considering the density and the classification of algae, which will be helpful to monitor sea pollution.
基金Supported by Financial support for this study was provided by Merck Sharp and Dohme(China)Ltd
文摘AIM: To describe a population of outpatients in China infected by hepatitis B virus (HBV) and/or hepatitis C virus (HCV), and assess their current management status. METHODS: A multicenter, cross-sectional study of HBV- and/or HCV-infected patients was conducted from August to November, 2011 in western China. Patients >= 18 years of age with HBV and/or HCV infections who visited outpatient departments at 10 hospitals were evaluated, whether treated or not. Data were collected on the day of visit from medical records and patient interviews. RESULTS: A total 4010 outpatients were analyzed, including 2562 HBV- infected and 1406 HCV-infected and 42 HBV/HCV co-infected patients. The median duration of documented infection was 7.5 years in HBV- infected and 1.8 years in HCV-infected patients. Cirrhosis was the most frequent hepatic complication (12.2%), appearing in one-third of patients within 3 years prior to or at diagnosis. The HCV genotype was determined in only 10% of HCV-infected patients. Biopsy data were only available for 54 patients (1.3%). Antiviral medications had been received by 58.2% of patients with HBV infection and 66.6% with HCV infection. Nucleos(t) ide analogs were the major antiviral medications prescribed for HBV- infected patients (most commonly adefovir dipivoxil and lamivudine). Ribavirin + pegylated interferon was prescribed for two-thirds of HCV-infected patients. In the previous 12 mo, around one-fifth patients had been hospitalized due to HBV or HCV infection. CONCLUSION: This observational, real-life study has identified some gaps between clinical practice and guideline recommendations in China. To achieve better health outcomes, several improvements, such as disease monitoring and optimizing antiviral regimens, should be made to improve disease management. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.
基金supported by the National Natural Science Foundation of China(Nos.52208369,52309138,52209142,51978666)the Department of Science and Technology of Sichuan Province(2023NSFSC0284).
文摘In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.
基金financially supported by the National Natural Science Foundation of China(grant No.41273066)
文摘As an important part of gas hydrates, light hydrocarbons (LHs), especially C5 to C7 hydrocarbons with various monomer compounds, provide a wide variety of geological and geochemical information, which have received much attention from organic geochemists and petroleum geologists.
基金supported by National Natural Science Foundation of China(Nos.51071069 and 51476061)Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization,China(No.2013A061401005)Key Laboratory of Efficient and Clean Energy Utilization of Guangdong Higher Education Institutes of China(No.KLB10004)
文摘A 1064 nm Nd:YAG laser was used to of the spectral lines measured from the laserablated ablate fly ash samples. The characteristics fly ash plasmas are presented with special attention to atomic and molecular carbon emission. It is shown that the intensity of the atomic line C I 192.9 nm is weak and the shot-to-shot intensity is fluctuant. The carbon atomic line C I 247.7 nm is relatively intensive and stable, however it is seriously interfered with by Fe I 247.8 nm. The intensity of the CN molecular line is close to that of C I 247.7 nm and the CN line is stable and less interfered with. The comparison of molecular CN emission under different conditions (air, Ar and N2) shows that the CN lines detected from the plasmas formed in an atmospheric environment are correlated with the reaction of carbon atoms in the plasma with the nitrogen in air, which indicates that the CN line is also important in pulsed laser ablation fly ash plasmas and this information can be incorporated in the detection of unburned carbon content in fly ash. Finally, a calibration curve is established with a correlation coefficient R2 of 0.999, using C I 247.7 nm and the CN molecular line as associated variables. In addition, accuracy is improved to a certain extent.
基金Nanning Excellent Young Scientist Program(RC20180206).
文摘[Objectives]This study aimed to establish a quality evaluation method for Herba Cistanche based on the HPLC characteristic chromatograms of the phenylethanoid glycosides and iridoid glycosides,and compare the HPLC characteristic chromatograms of different origins of Herba Cistanche.[Methods]The chromatographic conditions used were as follows:column,Agilent ZORBAX Eclipse Plus C18 column(4.6 mm×250 mm,5μm);gradient elution,acetonitrile-0.1%phosphoric acid aqueous solution;flow rate,1.0 mL/min;detection wavelength,240 nm;column temperature,30℃.[Results]Cistanche tubulosa(Schenk)Wight showed 9 characteristic peaks,Cistanche deserticola Y.C.Ma showed 10 characteristic peaks,Cistanche salsa(C.A.Mey.)G.Beck showed 7 characteristic peaks,and Cistanche sinensis G.Beck showed 4 characteristic peaks.Peak 6 was echinacoside,peak 7 was verbascoside,peak 8 was tubuloside A,peak 9 was isoacteoside and peak 10 was cistanoside A.The characteristic chromatograms of the four different origins of Herba Cistanche were significantly different.[Conclusions]This characteristic chromatogram method has good reproducibility and can be used to distinguish 4 different origins of Herba Cistanche,C.deserticola Y.C.Ma,C.tubulosa(Schenk)Wight,C.sinensis G.Beck and C.salsa(C.A.Mey.)G.Beck.
基金the National Basic Research Program (973) of China (No.2004CB418502,2003CB415002)the National Natural Science Foundation of China (No.29977002).
文摘The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp...
基金funded by the Key R&D and Promotion Projects of Henan Province,China(192102110152)。
文摘Recent investigations on pomegranate products have significantly increased and successfully drawn consumers’ attention to nutritional and medicinal values, promoting the pomegranate industry’s development worldwide. However, little information on pomegranates grown in China is available. Morphological and chemical characterizations of fruits and arils from 20 pomegranate cultivars in six regions of China were investigated. Combined with overall scores by principal component analysis, ‘Yushiliu No. 1’, ‘Taishanhong No. 2’, ‘Tunisia’ and ‘Mollar’ were promising cultivars, and Chinese researchers bred the first two. It was surprising that ‘Mollar’ had bigger fruit size and more aril moisture grown in China than in Spain. Cultivars with higher anthocyanin content in arils were ‘Turkey’, ‘Moyu’ and ‘Red Angel’, which might be used as the source of natural red food colourants. While red husk ‘Hongruyi’ and ‘Hongshuangxi’ with higher vitamin C, aril moisture and lower titratable acid in arils, might also be promising cultivars for further various utilization. Furthermore, the comparison of ‘Tunisia’ fruits from four regions revealed that cultivation locations had more influence on fruit traits than genotypes. Maturity index classification was established for Chinese pomegranate cultivars. Therefore, the results would provide a valuable guide for agricultural cultivation, industrial utilization, and breeding.
基金supported by National Natural Science Foundation of China (No. 51337006)
文摘This paper has researched the insulation characteristics of 10% c-C4F8/N2/CO2 mixtures under lightning impulse voltage by experiment. It is shown that the positive and negative lightning impulse breakdown voltages of 10%c-C4F8/N2/CO2 gas mixtures rise linearly as the electrode gap distance and gas pressure increase and under the same conditions, the positive lightning impulse breakdown voltage of the gas mixtures is always higher than the negative lightning impulse breakdown voltage. As the gas mixtures have a little higher liquefied temperature than SF6 and the comprehensive GWP is about 5% of SF6, and the positive and negative lightning impulse breakdown voltages can both reach 60% of SF6, 10%c-C4F8/N2/CO2 gas mixtures can be applied as insulation gas in electrical equipment such as C-GIS, GIT, GIL and so on.