Dynamic characteristics of UV enhanced gas–solid PVC chlorination process were revealed by a UV–Vis spectral online analysis method. Experimental results showed an instantaneous increase of the chlorination rate as ...Dynamic characteristics of UV enhanced gas–solid PVC chlorination process were revealed by a UV–Vis spectral online analysis method. Experimental results showed an instantaneous increase of the chlorination rate as soon as UV light was affiliated, which demonstrated the intensified effect of UV radiation on PVC chlorination directly.Different affiliation methods of UV light were then studied, proving that continuous UV radiation could enhance the chlorination process significantly while intermittent UV radiation was able to initiate the chlorination reaction once it was conducted. Besides, experiments were carried out to study the influences of parameters on the chlorination process such as UV wavelength, chlorination temperature, partial pressure of chlorine gas and PVC raw materials. Among all the parameters, chlorination temperature and partial pressure of chlorine gas were testified as two key factors to determine the chlorination performance. Thermal analysis of CPVC products showed that their corresponding properties such as the glass transition temperature(Tg) and the homogeneity of chlorine distribution in polymer phase were improved with the increase of chlorine content.展开更多
A new kinetic-spectrophotometric method is proposed for the determination of copper (Ⅱ). The method is based on the catalytic effect of copper (Ⅱ) on the oxidation of weak acid brilliant blue dye (RAWL) by hydrogen ...A new kinetic-spectrophotometric method is proposed for the determination of copper (Ⅱ). The method is based on the catalytic effect of copper (Ⅱ) on the oxidation of weak acid brilliant blue dye (RAWL) by hydrogen peroxide. The copper (Ⅱ) can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The optimum reaction conditions are as follows: pH 7.20, buffer solution NaOH-KH2PO4, RAWL (200 mg L-1) 5.00 mL, H2O2 (30%) 0.50 mL, reaction temperature 80℃ and reaction time 20 min. The linear range of this method is between 0 μg L-1 and 12 μg L-1 and the limit of detection is 0.011 μg L-1, the relative standard deviation (RSD) in five replicate determinations for 2 and 8 μg L-1 copper (Ⅱ) are 3.2% and 2.3%, respectively. Twenty ions do not interfere in the determination of copper (Ⅱ). The method has been applied satisfactorily to the determination of copper (Ⅱ) in freshwater samples (tap water and Yellow River water from Lijin, Shandong, China) and seawater samples (from the South China Sea), the recovery rates are 98.0%, 102.5% and 96.0%, respectively.展开更多
The author determined the occurrence of indole-3-acetic acid in sixteen Chinese marine algae collected from the east coast of China with fluorescence spectrophotometry (FS) and wheat coleop- tile bioanalysis methods (...The author determined the occurrence of indole-3-acetic acid in sixteen Chinese marine algae collected from the east coast of China with fluorescence spectrophotometry (FS) and wheat coleop- tile bioanalysis methods (WCB). The concentration of indole-3-acetic acid (IAA) presented was from 1.1–46.9 ng/g Fw (fresh weight) with FS and 5.3–110.2 ng/g Fw with WCB. The results by the two meth- ods were in the orders of 10-3–103 ng/g Fw reported previously from multiple references.展开更多
Coal samples obtained from Wanbei(WB),Pingxiang(PX),Liupanshui(LP),and Datong(DT) mines were pulverized,using either a vibration mill or a ball mill,to different degrees of fineness.The effect of the different grindin...Coal samples obtained from Wanbei(WB),Pingxiang(PX),Liupanshui(LP),and Datong(DT) mines were pulverized,using either a vibration mill or a ball mill,to different degrees of fineness.The effect of the different grinding methods on the mineral distribution within the pulverized coal was investigated by using proximate analysis,particle size analysis,and float-sink tests.The results show that the ash content in WB,PX,and DT coal increases with increasing particle size overall,while the ash content of the LP coal remain almost the same within each size fraction.In that case the ash in each fraction is similar to that of the raw coal.The ash versus size distributions for the same coal sample milled with the same grinding method to different degrees of fineness are similar.The ash versus size distribution of the coal powder with a 15% screen residue that was prepared with the vibration mill is different from the distribution of a similar sample prepared with a ball mill.The curves also vary between different coal samples.The grinding method has a great influence on the distribution of minerals across the various particle sizes.The float-sink tests and the laser particle size analysis results on PX and DT coal samples show that fines dominate the higher density fractions although the large +2.0 g/cm3 fraction was dominated by coarse particles.The size distribution of the low density fraction and +2.0 g/cm3 density fraction is bimodal.The size distribution of the intermediate density fraction is multimodal.展开更多
In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45--65℃ (with 55℃ being the optimum temperature) was isolated from oil-contaminated soil of Karamay in...In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45--65℃ (with 55℃ being the optimum temperature) was isolated from oil-contaminated soil of Karamay in Xinjiang, China. Denaturing gradient gel electrophoresis (DGGE) showed that there were nine strains included in KO8-2, which originated from the genera of Bacillus, Geobacillus and Clostridium. They all belonged to thermophilic bacteria, and had been previously proved as degraders of at least one petroleum fraction. The crude oil degraded by KO8-2 was analyzed by infrared spectrophotometry, hydrocarbon group type analysis and gas chromatography. The results indicated that the bacterial consortium KO8-2 was able to utilize 64.33% of saturates, 27.06% of aromatics, 13.24% of resins and the oil removal efficiency reached up to 58.73% at 55 ~C when the oil concentration was 10 g/L. Detailed analysis showed that KO8-2 was able to utilize the hydrocarbon components before C19, and the n-alkanes ranging from C20--C33 were signifi- cantly degraded. The ratios of nC17/Pr and nC18/Ph were 3.12 and 3.87, respectively, before degradation, whereas after degradation the ratios reduced to 0.21 and 0.38, respectively. Compared with the control sample, the oil removal efficiency in KO8-2 composting reactor reached 50.12% after a degradation duration of 60 days.展开更多
The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was ...The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was also performed to explain possible effects. From particle size analysis and strength tests, it is hypothesized that the strength of the soil is increased with the addition of certain salinity concentrations until there are reversed effects, which is between 20 g/L and 50 g/L from our study. The increase of strength is suggested to be the affect of a greater variety of particle sizes. Since NaCI plays a role in the particle size distribution, it also plays a role in the strength of soils. The degree of the effect of the water content also differs from concentrations, and could be due to the variation of hydration film thickness on particles, which is affected by the ions introduced from water.展开更多
A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and ...A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and graphing spectral intensity versus frequency in a bar graph of the selected groups, distinguished by color and/or line-type. This allows for easy detection of regular patterns buried in the observed spectrum. Furthermore, it includes a Loomis-Wood view for assisting in spectral assignments. As an example, the program was applied in assigning the molecular spectrum of the production in the discharge of PCl3 buffered by helium gas, which may belong to several species. The results suggest that the program is highly efficient and quite useful in the assignment and the analysis of molecular spectra, especially those of symmetric top, slightly asymmetric top and linear molecules. The accuracy and efficiency of this program will likely ensure its wide application in the processing of molecular spectra.展开更多
Liquid argon flow along a nanochannel is studied using molecular dynamics (MD) simulation in this work.Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) is used as the MD simulator.The effects of redu...Liquid argon flow along a nanochannel is studied using molecular dynamics (MD) simulation in this work.Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) is used as the MD simulator.The effects of reduced forces at 0.5,1.0 and 2.0 on argon flow on system energy in the form of system potential energy,pressure and velocity profile are described.Output in the form of three-dimensional visualization of the system at steady-state condition using Visual Molecular Dynamics (VMD) is provided to describe the dynamics of the argon atoms.The equilibrium state is reached after 16000 time steps.The effects on system energy,pressure and velocity profile due to reduced force of 2.0 (F2) are clearly distinguishable from the other two lower forces where sufficiently high net force along the direction of the nanochannel for F2 renders the attractive and repulsive forces between the argon atoms virtually non-existent.A reduced force of 0.5 (F0.5) provides liquid argon flow that approaches Poiseuille (laminar) flow as clearly shown by the n-shaped average velocity profile.The extension of the present MD model to a more practical application affords scientists and engineers a good option for simulation of other nanofluidic dynamics processes.展开更多
Byrsonima intermedia A Juss. is a species with pharmacological properties from the Brazilian Cerrado that shows difficulties related to sexual propagation. Research on cell viability may provide useful information for...Byrsonima intermedia A Juss. is a species with pharmacological properties from the Brazilian Cerrado that shows difficulties related to sexual propagation. Research on cell viability may provide useful information for the selection of cells with embryogenic potential during the callus culture, Within this context, our research is aimed at establishing the cell viability of calli from Byrsonima intermedia leaf segments. The calli went through three subculture phases, of 60 days each, in MS medium with 0.09 M sucrose, 0.6% agar, pH 5.8 and 4.52 laM 2,4-D. The calli were stored in dark conditions and samples were collected every 10 days from each subculture for viability tests with fluorescein 3,6-diacetate (FDA) and 2,3,5-triphenyltetrazolium chloride (TTC). The staining methods allowed quantifying cell viability in each subculture. The best results from the FDA tests were obtained at 21, 25 and 29 days for the first, second and third subcultures respectively, with 53,86%, 61.88% and 53.73% viable cells. Regarding the TTC test, the largest absorbance values were obtained at 21, 27 and 28 days for the first, second and third subcultures respectively. Fluorescence and spectrophotometry analyses were efficient for determination of cell viability during callus cultivation period.展开更多
A dual wavelength differential first derivative spectrophotometric method has been developed to standardize the concentration of a saturated aqueous solution of carbon monoxide (CO) as the standard and to identify and...A dual wavelength differential first derivative spectrophotometric method has been developed to standardize the concentration of a saturated aqueous solution of carbon monoxide (CO) as the standard and to identify and to determine CO formed during the microsomal metabolism of xenobiotics in vitro. The method can significantly eliminate the background interference in the assay media and increase the quantitative accuracy and the sensitivity. There is a good linear relationship between CO concentration in the range of 2~10 μmol·L 1 CO and the distance D between the first derivative peak at 415 nm amd valley at 426 nm with r=0.9999(n=5),the regression equation being C (mmol·L 1 )=17.6D 0.4, the detection limit lower than 0.1 μmol·L 1 CO. The average recoveries of CO from the assay system and the sample were 102.1%, RSD=2.9% (n=7) and 79.7%, RSD=6.8% (n=12),respectively. The RSD of within day was 4.4%(n=18),and the RSD of day to day was 6.1%(n=16). By this method, four trihaloanilines and one trihalobenzene were tested, the results showed that only 2,4,5 trifluoroaniline could be converted to CO by the incubation with rat hepatic microsomes, NADPH and oxygen, the ability of phenobarbital or dexamethasone to induce rat hepatic microsomes to catalyze CO formation was 3 or 8 times higher than that of the control.展开更多
The earth crust is believed to be made of a mass of minerals and is matched by their importance in human life. The human body, depend like other leaving organisms, on several minerals as essential constituents of its ...The earth crust is believed to be made of a mass of minerals and is matched by their importance in human life. The human body, depend like other leaving organisms, on several minerals as essential constituents of its existence. Metal ions in foodstuff are in different chemical forms, as inorganic salts or organic molecules or complexes with other compounds such as proteins, amino acids, enzymes and some vitamins, among others, that play an important role in human health. Entomophagy, insect consumption by several ethnic groups in Mexico as cultural tradition since prehispanic era represent an option for population to obtain the minerals needed by the body to keep a good health. Escamoles ant eggs of the Liometopumapiculatum M genus, much appreciated either at rural communities as well as in urban cities, contain minerals with a favorable effect in human health. The aim of this study was to investigate the mineral composition of Escamoles and the benefits which can provide to the human body. Sampling was at an arid region of the Hidalgo state on April 2012. Minerals in dry basis, determined by atomic absorption spectrophotometry, with the exception of phosphorus content, obtained from a triple acid digested extract and determined colorimetrically. Data of mineral analysis in dry basis of Escamoles were: total minerals 5.92%; Na 0.079%; K 0.075%; Ca 0.097%; P 0.701%; Fe 0.021%; Zn 0.035% Cu 0.009%; Mg 0.998%; Mn 0.002%. Minerals quantify are not equal to total ash contained because not all of them were assess determined. Elements concentration depends not only on the total mineral composition of foodstuff the inorganic or organic form or interaction among metal ions, but also on their availability and avail of them. Minerals in Escamoles ant eggs have a considerable influence in the condition of human health.展开更多
[Objective]The aim was to find a way to measure the cholesterol content in deserted oil.[Method]Dual-wavelength spectrophotometry method was used for the determination of cholesterol in edible oil.630 nm and 720 nm we...[Objective]The aim was to find a way to measure the cholesterol content in deserted oil.[Method]Dual-wavelength spectrophotometry method was used for the determination of cholesterol in edible oil.630 nm and 720 nm were set as target band and reference band in this method,respectively.The result was compared to liquid chromatography method.[Result]The relative standard deviation(RSD)was at 1.26% and recovery was between 101.9% and 110.7%.Linear range was 8.0-40.0 μg/ml.The tested result was close to the result of liquid chromatography.[Conclusion]It was proved that this method was easy,fast and accurate.The disturbance of sitosterol was eliminated without isolation.It can be used for fast identification of the authenticity of waste fat.展开更多
An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. Th...An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. The thermal analysis of the flat heat pipe radiator for cooling high-power light emitting diode (LED) array was conducted. The thermal characteristics of the flat heat pipe radiator under the different heat loads and incline angles were investigated experimentally in natural convection. An electro-thermal conversion method was used to measure the junction temperature of the LED chips. It is found that the integral temperature distribution of the flat heat pipe radiator is reasonable and uniform. The total thermal resistance of the flat heat pipe radiator varies in the range of 0.38-0.45 K/W. The junction temperatures of LED chips with the flat heat pipe radiator and with the aluminum board at the same forward current of 0.35 A are 52.5 and 75.2 ℃, respectively.展开更多
A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe(II)-ferrozine complex was reacted with cetyltrimethylammonium bromide (CTAB...A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe(II)-ferrozine complex was reacted with cetyltrimethylammonium bromide (CTAB) to form a Fe(II)-ferrozine-CTAB paired compound, which was collected on a membrane by filtration under vacuum. The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis. Various factors affecting the iron collection and determination were investigated. With different sample preconcentration volumes, the range of determination was broadened to 0.5-120 ~tg/L. The detection limit of this method reached 0.19 ktg/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45. The relative standard deviation (n = 7) was 1.9% for samples containing 10 ~g/L Fe. Twelve seawater samples were analyzed on-site using the proposed method, and two were also analyzed in inductively coupled plasma mass spectrometry. No significant difference was shown between the two methods by the Student's t-test. The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple, accurate and inexpensive.展开更多
基金Supported by the National Science and Technology Key Supporting Project(2013BAF08B05)the National Natural Science Foundation of China(21176137)
文摘Dynamic characteristics of UV enhanced gas–solid PVC chlorination process were revealed by a UV–Vis spectral online analysis method. Experimental results showed an instantaneous increase of the chlorination rate as soon as UV light was affiliated, which demonstrated the intensified effect of UV radiation on PVC chlorination directly.Different affiliation methods of UV light were then studied, proving that continuous UV radiation could enhance the chlorination process significantly while intermittent UV radiation was able to initiate the chlorination reaction once it was conducted. Besides, experiments were carried out to study the influences of parameters on the chlorination process such as UV wavelength, chlorination temperature, partial pressure of chlorine gas and PVC raw materials. Among all the parameters, chlorination temperature and partial pressure of chlorine gas were testified as two key factors to determine the chlorination performance. Thermal analysis of CPVC products showed that their corresponding properties such as the glass transition temperature(Tg) and the homogeneity of chlorine distribution in polymer phase were improved with the increase of chlorine content.
文摘A new kinetic-spectrophotometric method is proposed for the determination of copper (Ⅱ). The method is based on the catalytic effect of copper (Ⅱ) on the oxidation of weak acid brilliant blue dye (RAWL) by hydrogen peroxide. The copper (Ⅱ) can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The optimum reaction conditions are as follows: pH 7.20, buffer solution NaOH-KH2PO4, RAWL (200 mg L-1) 5.00 mL, H2O2 (30%) 0.50 mL, reaction temperature 80℃ and reaction time 20 min. The linear range of this method is between 0 μg L-1 and 12 μg L-1 and the limit of detection is 0.011 μg L-1, the relative standard deviation (RSD) in five replicate determinations for 2 and 8 μg L-1 copper (Ⅱ) are 3.2% and 2.3%, respectively. Twenty ions do not interfere in the determination of copper (Ⅱ). The method has been applied satisfactorily to the determination of copper (Ⅱ) in freshwater samples (tap water and Yellow River water from Lijin, Shandong, China) and seawater samples (from the South China Sea), the recovery rates are 98.0%, 102.5% and 96.0%, respectively.
基金Supported No. 30530080 by the NSFC, and by Qingdao Bureau of Science and Technology (No. 04-2-NN-26).
文摘The author determined the occurrence of indole-3-acetic acid in sixteen Chinese marine algae collected from the east coast of China with fluorescence spectrophotometry (FS) and wheat coleop- tile bioanalysis methods (WCB). The concentration of indole-3-acetic acid (IAA) presented was from 1.1–46.9 ng/g Fw (fresh weight) with FS and 5.3–110.2 ng/g Fw with WCB. The results by the two meth- ods were in the orders of 10-3–103 ng/g Fw reported previously from multiple references.
基金supported by the Funds for Creative Research Groups of China (No. 50921002)the National Natural Science Foundation of China (Nos. 50676103 and 51104160)
文摘Coal samples obtained from Wanbei(WB),Pingxiang(PX),Liupanshui(LP),and Datong(DT) mines were pulverized,using either a vibration mill or a ball mill,to different degrees of fineness.The effect of the different grinding methods on the mineral distribution within the pulverized coal was investigated by using proximate analysis,particle size analysis,and float-sink tests.The results show that the ash content in WB,PX,and DT coal increases with increasing particle size overall,while the ash content of the LP coal remain almost the same within each size fraction.In that case the ash in each fraction is similar to that of the raw coal.The ash versus size distributions for the same coal sample milled with the same grinding method to different degrees of fineness are similar.The ash versus size distribution of the coal powder with a 15% screen residue that was prepared with the vibration mill is different from the distribution of a similar sample prepared with a ball mill.The curves also vary between different coal samples.The grinding method has a great influence on the distribution of minerals across the various particle sizes.The float-sink tests and the laser particle size analysis results on PX and DT coal samples show that fines dominate the higher density fractions although the large +2.0 g/cm3 fraction was dominated by coarse particles.The size distribution of the low density fraction and +2.0 g/cm3 density fraction is bimodal.The size distribution of the intermediate density fraction is multimodal.
基金the support provided by the Research&Technology Development Project of China National Petroleum Corporation(No.2008D-4704-2)
文摘In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45--65℃ (with 55℃ being the optimum temperature) was isolated from oil-contaminated soil of Karamay in Xinjiang, China. Denaturing gradient gel electrophoresis (DGGE) showed that there were nine strains included in KO8-2, which originated from the genera of Bacillus, Geobacillus and Clostridium. They all belonged to thermophilic bacteria, and had been previously proved as degraders of at least one petroleum fraction. The crude oil degraded by KO8-2 was analyzed by infrared spectrophotometry, hydrocarbon group type analysis and gas chromatography. The results indicated that the bacterial consortium KO8-2 was able to utilize 64.33% of saturates, 27.06% of aromatics, 13.24% of resins and the oil removal efficiency reached up to 58.73% at 55 ~C when the oil concentration was 10 g/L. Detailed analysis showed that KO8-2 was able to utilize the hydrocarbon components before C19, and the n-alkanes ranging from C20--C33 were signifi- cantly degraded. The ratios of nC17/Pr and nC18/Ph were 3.12 and 3.87, respectively, before degradation, whereas after degradation the ratios reduced to 0.21 and 0.38, respectively. Compared with the control sample, the oil removal efficiency in KO8-2 composting reactor reached 50.12% after a degradation duration of 60 days.
基金Acknowledgements: This work was supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, SEM, China, and also supported by the United States National Science Foundation. The authors thank Prof. SHEN H. H. and Prof. SHEN H. T. from Clarkson University for their unconditional support to this work.
文摘The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was also performed to explain possible effects. From particle size analysis and strength tests, it is hypothesized that the strength of the soil is increased with the addition of certain salinity concentrations until there are reversed effects, which is between 20 g/L and 50 g/L from our study. The increase of strength is suggested to be the affect of a greater variety of particle sizes. Since NaCI plays a role in the particle size distribution, it also plays a role in the strength of soils. The degree of the effect of the water content also differs from concentrations, and could be due to the variation of hydration film thickness on particles, which is affected by the ions introduced from water.
基金This work was supported by the National Natural Science Foundation of China (NSFC No.10574045 and No.10434060)and Science and Technology Commission of Shanghai Municipality(No.04DZ14009).The authors are grateful to Hua-huiZhu for his valuable suggestions.
文摘A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and graphing spectral intensity versus frequency in a bar graph of the selected groups, distinguished by color and/or line-type. This allows for easy detection of regular patterns buried in the observed spectrum. Furthermore, it includes a Loomis-Wood view for assisting in spectral assignments. As an example, the program was applied in assigning the molecular spectrum of the production in the discharge of PCl3 buffered by helium gas, which may belong to several species. The results suggest that the program is highly efficient and quite useful in the assignment and the analysis of molecular spectra, especially those of symmetric top, slightly asymmetric top and linear molecules. The accuracy and efficiency of this program will likely ensure its wide application in the processing of molecular spectra.
基金Supported by the Academy of Sciences,Malaysia and Ministry of Science and Technology & Innovation
文摘Liquid argon flow along a nanochannel is studied using molecular dynamics (MD) simulation in this work.Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) is used as the MD simulator.The effects of reduced forces at 0.5,1.0 and 2.0 on argon flow on system energy in the form of system potential energy,pressure and velocity profile are described.Output in the form of three-dimensional visualization of the system at steady-state condition using Visual Molecular Dynamics (VMD) is provided to describe the dynamics of the argon atoms.The equilibrium state is reached after 16000 time steps.The effects on system energy,pressure and velocity profile due to reduced force of 2.0 (F2) are clearly distinguishable from the other two lower forces where sufficiently high net force along the direction of the nanochannel for F2 renders the attractive and repulsive forces between the argon atoms virtually non-existent.A reduced force of 0.5 (F0.5) provides liquid argon flow that approaches Poiseuille (laminar) flow as clearly shown by the n-shaped average velocity profile.The extension of the present MD model to a more practical application affords scientists and engineers a good option for simulation of other nanofluidic dynamics processes.
文摘Byrsonima intermedia A Juss. is a species with pharmacological properties from the Brazilian Cerrado that shows difficulties related to sexual propagation. Research on cell viability may provide useful information for the selection of cells with embryogenic potential during the callus culture, Within this context, our research is aimed at establishing the cell viability of calli from Byrsonima intermedia leaf segments. The calli went through three subculture phases, of 60 days each, in MS medium with 0.09 M sucrose, 0.6% agar, pH 5.8 and 4.52 laM 2,4-D. The calli were stored in dark conditions and samples were collected every 10 days from each subculture for viability tests with fluorescein 3,6-diacetate (FDA) and 2,3,5-triphenyltetrazolium chloride (TTC). The staining methods allowed quantifying cell viability in each subculture. The best results from the FDA tests were obtained at 21, 25 and 29 days for the first, second and third subcultures respectively, with 53,86%, 61.88% and 53.73% viable cells. Regarding the TTC test, the largest absorbance values were obtained at 21, 27 and 28 days for the first, second and third subcultures respectively. Fluorescence and spectrophotometry analyses were efficient for determination of cell viability during callus cultivation period.
文摘A dual wavelength differential first derivative spectrophotometric method has been developed to standardize the concentration of a saturated aqueous solution of carbon monoxide (CO) as the standard and to identify and to determine CO formed during the microsomal metabolism of xenobiotics in vitro. The method can significantly eliminate the background interference in the assay media and increase the quantitative accuracy and the sensitivity. There is a good linear relationship between CO concentration in the range of 2~10 μmol·L 1 CO and the distance D between the first derivative peak at 415 nm amd valley at 426 nm with r=0.9999(n=5),the regression equation being C (mmol·L 1 )=17.6D 0.4, the detection limit lower than 0.1 μmol·L 1 CO. The average recoveries of CO from the assay system and the sample were 102.1%, RSD=2.9% (n=7) and 79.7%, RSD=6.8% (n=12),respectively. The RSD of within day was 4.4%(n=18),and the RSD of day to day was 6.1%(n=16). By this method, four trihaloanilines and one trihalobenzene were tested, the results showed that only 2,4,5 trifluoroaniline could be converted to CO by the incubation with rat hepatic microsomes, NADPH and oxygen, the ability of phenobarbital or dexamethasone to induce rat hepatic microsomes to catalyze CO formation was 3 or 8 times higher than that of the control.
文摘The earth crust is believed to be made of a mass of minerals and is matched by their importance in human life. The human body, depend like other leaving organisms, on several minerals as essential constituents of its existence. Metal ions in foodstuff are in different chemical forms, as inorganic salts or organic molecules or complexes with other compounds such as proteins, amino acids, enzymes and some vitamins, among others, that play an important role in human health. Entomophagy, insect consumption by several ethnic groups in Mexico as cultural tradition since prehispanic era represent an option for population to obtain the minerals needed by the body to keep a good health. Escamoles ant eggs of the Liometopumapiculatum M genus, much appreciated either at rural communities as well as in urban cities, contain minerals with a favorable effect in human health. The aim of this study was to investigate the mineral composition of Escamoles and the benefits which can provide to the human body. Sampling was at an arid region of the Hidalgo state on April 2012. Minerals in dry basis, determined by atomic absorption spectrophotometry, with the exception of phosphorus content, obtained from a triple acid digested extract and determined colorimetrically. Data of mineral analysis in dry basis of Escamoles were: total minerals 5.92%; Na 0.079%; K 0.075%; Ca 0.097%; P 0.701%; Fe 0.021%; Zn 0.035% Cu 0.009%; Mg 0.998%; Mn 0.002%. Minerals quantify are not equal to total ash contained because not all of them were assess determined. Elements concentration depends not only on the total mineral composition of foodstuff the inorganic or organic form or interaction among metal ions, but also on their availability and avail of them. Minerals in Escamoles ant eggs have a considerable influence in the condition of human health.
基金Supported by National Quality Inspection Bureau(KJ092102,2009QK146)
文摘[Objective]The aim was to find a way to measure the cholesterol content in deserted oil.[Method]Dual-wavelength spectrophotometry method was used for the determination of cholesterol in edible oil.630 nm and 720 nm were set as target band and reference band in this method,respectively.The result was compared to liquid chromatography method.[Result]The relative standard deviation(RSD)was at 1.26% and recovery was between 101.9% and 110.7%.Linear range was 8.0-40.0 μg/ml.The tested result was close to the result of liquid chromatography.[Conclusion]It was proved that this method was easy,fast and accurate.The disturbance of sitosterol was eliminated without isolation.It can be used for fast identification of the authenticity of waste fat.
基金Project(50876016) support by the National Natural Science Foundation of China
文摘An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. The thermal analysis of the flat heat pipe radiator for cooling high-power light emitting diode (LED) array was conducted. The thermal characteristics of the flat heat pipe radiator under the different heat loads and incline angles were investigated experimentally in natural convection. An electro-thermal conversion method was used to measure the junction temperature of the LED chips. It is found that the integral temperature distribution of the flat heat pipe radiator is reasonable and uniform. The total thermal resistance of the flat heat pipe radiator varies in the range of 0.38-0.45 K/W. The junction temperatures of LED chips with the flat heat pipe radiator and with the aluminum board at the same forward current of 0.35 A are 52.5 and 75.2 ℃, respectively.
基金Supported by State Key Laboratory of Marine Environmental Science(MEL)Funds(No.MELRI1001)
文摘A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe(II)-ferrozine complex was reacted with cetyltrimethylammonium bromide (CTAB) to form a Fe(II)-ferrozine-CTAB paired compound, which was collected on a membrane by filtration under vacuum. The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis. Various factors affecting the iron collection and determination were investigated. With different sample preconcentration volumes, the range of determination was broadened to 0.5-120 ~tg/L. The detection limit of this method reached 0.19 ktg/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45. The relative standard deviation (n = 7) was 1.9% for samples containing 10 ~g/L Fe. Twelve seawater samples were analyzed on-site using the proposed method, and two were also analyzed in inductively coupled plasma mass spectrometry. No significant difference was shown between the two methods by the Student's t-test. The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple, accurate and inexpensive.