The effects of temperature,pH and long-term storage on the secondary structure and conformation changes of bovine haemoglobin（bHb） were studied using circular dichroism（CD） and ultraviolet-visible（UV-vis） spectr...The effects of temperature,pH and long-term storage on the secondary structure and conformation changes of bovine haemoglobin（bHb） were studied using circular dichroism（CD） and ultraviolet-visible（UV-vis） spectroscopies.Neural network software was used to deconvolute the CD data to obtain the fractional content of the five secondary structures.The storage stability of bHb solutions in pH 6,7 and8 buffers was significantly higher at 4 ℃ than at 23 ℃ for the first 3 days.A complete denaturation of bHb was observed after 40 days irrespective of storage temperature or pH.The bHb solutions were also exposed to heating and cooling cycles between 25 and 65 ℃ and structural changes were followed by UVvis and CD spectroscopies.These experiments demonstrated that α-helix content of bHb decreased steadily with the increasing temperature above 35 ℃ at all pH values.The loss in a-helicity and gain in random coil conformations was pH-dependent and the greatest under alkaline conditions.Furthermore,there was minimal recovery of the secondary structure content upon cooling to 25 ℃.The use of bHb as a model drug is very common and this study elucidates the significance of storage and processing conditions on its stability.展开更多
In order to differentiate regions, varieties, and parts of tobacco leaves, two pattern recognition methods through pattern classification modeling were developed based on the comprehensive information of ultraviolet-v...In order to differentiate regions, varieties, and parts of tobacco leaves, two pattern recognition methods through pattern classification modeling were developed based on the comprehensive information of ultraviolet-visible spectroscopy （UV-VIS） by employing one-way analysis of variance （ANOVA1） and wave range random combination （WRRC） technology from MATLAB. This proposed classification method has never been reported previously and the instrument and operation for this method is much more convenient and efficient than previous reported classification methods. The result of this paper demonstrated that the spectral features extracted by ANOVAI and WRRC methods could be used to differentiate tobacco leaves with different patterns. The ANOVAI method had a training recognition rate range of 75.00-87.50%,4 and a validation recognition rate range of 57.14-100%. The WRRC method had a training recognition rate range of 75.00-94.12% and a validation recognition rate range of 66.67-100%. The ANOVAI method is more convenient and efficient in model developing, while the WRRC method utilizes fewer model variables and is more robust.展开更多
Phosphorus fertilizers from less pure sedimentary sources become increasingly important, due to depletion of phosphorus from igneous rock of high quality. Consequently, robust methods with potential to remove various ...Phosphorus fertilizers from less pure sedimentary sources become increasingly important, due to depletion of phosphorus from igneous rock of high quality. Consequently, robust methods with potential to remove various types of hazardous elements are required. Among such impurities, hexavalent chromium (Cr(VI)) is very likely to become a future challenge. Different industrial ways to treat phosphate rock are currently being practised, and we have here studied how chromium behaves when using the nitro-phosphate process. The reduction mechanism of Cr (VI) in nitric acid and phosphoric acid solutions was investigated by measuring redox potential and UV-VIS spectra. The results show that Cr (VI) is not stable in strong nitric acid solutions. Reduction of Cr (VI) species decreased with decreasing temperature, NO<sub>2</sub> concentration, ionic strength and absence of light. These findings support the proposed reduction reaction:The reduction rate was observed proportional to the nitric acid decomposition: .展开更多
In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visibl...In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.展开更多
Dissolved organic matter(DOM) plays important roles in soil biogeochemistry activity and nutrients transportation in soils, but studies regarding the long-term effects of green manures on the content and structure of ...Dissolved organic matter(DOM) plays important roles in soil biogeochemistry activity and nutrients transportation in soils, but studies regarding the long-term effects of green manures on the content and structure of DOM in red paddy soil have not been reported yet. A long-term green manure experiment established in 1982 was utilized to test the DOM contents in different treatments, and the spectral characteristics of DOM were investigated by using ultraviolet-visible(UV-Vis) spectrometry and Fourier transform infrared(FTIR) spectrometry. The experiment included four cropping systems: ricerice-milk vetch(RRV), rice-rice-rape(RRP), rice-rice-ryegrass(RRG) and rice-rice-winter fallow(RRF), among them, milk vetch, rape, and ryegrass are popular winter green manure species in southern China. The results showed that the content of dissolved organic carbon(DOC), which is widely used to estimate the concentration of DOM, was significantly promoted after the incorporation of green manures compared with the other sampling stages. The contents of aromatic groups and the degree of humification of DOM increased in RRV and RRP, suggesting more complex compositions of the soil DOM after long-term application of milk vetch and rape. The contents of phenol, alcohol and carboxylic acid group at the mature stage of early rice were significantly higher than those at the stage of after green manures turned over, especially for the RRV treatment. The absorption ratio of FTIR indicated that winter plantation of rape increased the aromatic-C/aliphatic-C ratio, and ryegrass increased the aromatic-C/carboxyl-C ratio. In conclusion, long-term planting of milk vetch and rape as green manures increased the degree of aromaticity, humification and average molecular weight of DOM, and made the DOM more stable in red paddy soil.展开更多
The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9 782 μg/g for Ca to 432 μ...The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9 782 μg/g for Ca to 432 μg/g for Na whereas K, Mg, Mn, Ni, Cr, Zn, Pb, and Cu, which occurred at trace levels ranged from 673.73 μg/g for Mg to 2.97 μg/g for Mn. The results of the quantitative analysis of porphyrins extracted from the coal minerals showed that Onyeama coal has the highest amount of porphyrins (ca～0.96 μg/g) while Okpara has the lowest (ca～0.30 μg/g). The porphyrins were qualitatively characterized by a combination of thin layer chromatography (TLC), infrared, and ultraviolet-visible spectrophotometers. The results of the mid infrared analysis (MIR) showed the presence of absorption bands at 3 440 cm～1～3 450 cm-1 and 1 640 cm-1～1 680 cm-1 , which are owing to the stretching vibrations of N ─ H and C─ C of aromatics, with C─ H out of plane (oop) bending vibrations at wavenumbers less than 900 cm-1, all of which are characteristic absorptions of porphyrin free base. The ultraviolet-visible data showed prominent peaks at ～400 nm(Soret band) and at wavelength ranges of 535 nm～550 nm(β-band) and 565 nm～ 600 nm (α-band) for the coal porphyrins analyzed. The geochemical significance of the metals and porphyrins in coal minerals are discussed.展开更多
Fourier-transform infrared（FTIR）,Raman and ultraviolet-visible spectra of 4,4＇-bipyridine and its me-tal-organic coordination compounds synthesized from 4,4＇-bipyridine and nitrate of Co（Ⅱ）,Ni（Ⅱ） and Zn（Ⅱ...Fourier-transform infrared（FTIR）,Raman and ultraviolet-visible spectra of 4,4＇-bipyridine and its me-tal-organic coordination compounds synthesized from 4,4＇-bipyridine and nitrate of Co（Ⅱ）,Ni（Ⅱ） and Zn（Ⅱ） were measured and analyzed,respectively.The main FTIR and Raman bands were assigned in detail.The relationship between these characteristic bands and the structure of ligands and coordination compounds were discussed.展开更多
The lithium-sulfur(Li-S)battery is one of the most promising substitutes for current energy storage systems because of its low cost,high theoretical capacity,and high energy density.However,the high solubility of inte...The lithium-sulfur(Li-S)battery is one of the most promising substitutes for current energy storage systems because of its low cost,high theoretical capacity,and high energy density.However,the high solubility of intermediate products(i.e.,lithium polysulfides)and the resultant shuttle effect lead to rapidly fading capacity and a low coulombic efficiency,which hinder the practical application of Li-S batteries.In this study,block copolymers are constructed with both an ethylene oxide unit and a styrene unit and then used as binders for Li-S batteries.Electrochemical performance improvements are attributed to the synergistic effects contributed by the different units of the block copolymer.The ethylene oxide unit traps polysulfide,which bonds strongly with the intermediate lithium polysulfide,and enhances the transport of lithium ions to reach high capacity.Meanwhile,the styrene unit maintains cathode integrity by improving the mechanical properties and elasticity of the constructed block copolymer to accommodate the large volume changes.By enabling multiple functions via different units in the polymer chain,high sulfur utilization is achieved,polysulfide diffusion is confined,and the shuttle effect is suppressed during the cycle life of Li-S batteries,as revealed by operando ultraviolet-visible spectroscopy and S Kedge X-ray absorption spectroscopy.展开更多
Stable and monodispersed silver nanoparticles were produced through a mild,convenient,one-pot method based on the reduction of silver nitrate in the presence of poly(amic acid) (PAA) as a stabilizer.The surface plasma...Stable and monodispersed silver nanoparticles were produced through a mild,convenient,one-pot method based on the reduction of silver nitrate in the presence of poly(amic acid) (PAA) as a stabilizer.The surface plasma band transition was monitored along with time in the reaction mixture for three sets of experiments by ultraviolet-visible spectroscopy.Analysis of the data with the Avrami equation yielded n exponent with values between 0.5 and 1.5,demonstrating three-dimensional heterogeneous nucleation and diffusion-controlled growth,accompanied by soft impingement effect.XRD and TEM analyses show a softly agglomerated polycrystalline state and a nearly spherical morphology (<50 nm) of nanoparticles.The FT-IR result indicates that the PAA molecular structure could be hardly influenced by the formation of nanoparticles.展开更多
Raman spectra and ultraviolet-visible（UV-Vis） absorption spectra of linear polyene molecule-canthaxan-thin in n-hexane are measured and analyzed.In addition,the optimized structure of canthaxanthin was calculated vi...Raman spectra and ultraviolet-visible（UV-Vis） absorption spectra of linear polyene molecule-canthaxan-thin in n-hexane are measured and analyzed.In addition,the optimized structure of canthaxanthin was calculated via density functional theory（DFT） functional B3LYP.With decreasing the concentration,Raman scattering cross section （RSCS） of fundamental frequency is extremely high,and the UV-Vis absorption bands become narrower.The results of coherent weakly damped electron-Lattice vibration model were analyzed.展开更多
New Schiff base polymers poly[4,4＇-methylenebis（cinnamaldehyde）ethylenediimine] （PMBCen）, poly[4,4＇- methylenebis（cinnamaldehyde）1,2-propylenediimine] （PMBCPn）, poly[4,4＇-methylenebis（cinnamaldehyde）1,3-p...New Schiff base polymers poly[4,4＇-methylenebis（cinnamaldehyde）ethylenediimine] （PMBCen）, poly[4,4＇- methylenebis（cinnamaldehyde）1,2-propylenediimine] （PMBCPn）, poly[4,4＇-methylenebis（cinnamaldehyde）1,3-propylenediimine] （PMBCPR）, poly[4,4＇-methylenebis（cinnamaldehyde） 1,2-phenylenediimine] （PMBCPh）, poly[4,4＇-methylenebis（cinnamaldehyde）meso-stilbenediimine] （PMBCS）, poly[4,4＇-methylenebis（cinnamaldehyde）urea] （PMBCUR）, poly[4,4＇- methylenebis（cinnamaldehyde）semicarbazone] （PMBCSc）, poly[4,4＇-methylenebis（cinnamaldehyde）thiosemicarbazone] （PMBCTSc） and poly[4,4＇-methylenebis（cinnamaldehyde）hydrazone] （PMBCH） were formed by polycondensation of 4,4＇- methylenebis（cinnamaldehyde） with ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-phenylenediamine, meso-stilbenediamine, urea, semicarbazide, thiosemicarbazide and hydrazine, respectively. The dialdehyde and polymers have been characterized through elemental micro-analysis, IR, UV-Vis and ^1H-NMR spectroscopic techniques. Thermoanalytical studies and viscous flow of dilute solutions of dialdehyde and its polymers have been examined and compared.展开更多
Urea L-malic acid, a new second order nonlinear optical crystal, was studied using density functional theory （DFT）. PBEPBE/6-31＋G（d,p） method, the optimal method for comparing the results from the several DFT met...Urea L-malic acid, a new second order nonlinear optical crystal, was studied using density functional theory （DFT）. PBEPBE/6-31＋G（d,p） method, the optimal method for comparing the results from the several DFT methods, was chosen to study the molecular structure. Infrared and ultraviolet-visible spectra were obtained and compared with experiments. The ultraviolet-visible spectrum was also analyzed by the molecular orbital population. The geometries, and the infrared and ultraviolet-visible spectra in water were studied using DFT methods in combination with the polarized continuum model to predict the perturbations by the solvent effect.展开更多
The increasing importance of endothelium-derived relaxing factor(EDRF),which has now been identified as nitric oxide (NO),has been underscored by the eltlcidation of its role'in a growing number of normal and path...The increasing importance of endothelium-derived relaxing factor(EDRF),which has now been identified as nitric oxide (NO),has been underscored by the eltlcidation of its role'in a growing number of normal and pathophysiological processes. Therefore techniques for detection of nitric oxide should serve as useful tools in defining the role of nitric oxide to these processes.We have improved a simple, sensitive assay methods for determination of nitric oxide in blood, tissue, and other body fluids both by fluorometric and by ultraviolet-visible spectrophotometric measurements. Data obtained by floores cence and by UV-visible assay were correlated well (r=0. 9938, P<0. 0001 ).Linearity:0.1￣ 100μmol/L,r =0.9996,P<0.0001. The minimum detection limit were < 10pmol/L. Within-and between-run CVs were 2. 48%and 4. 62% (n = 10),respectively.Reference values for healthy adults(n=40) were(9.82 ± 1. 57) pmol/L. In conclusion:the methods is sensitive, specific,and precise. It is fairly rapid and simple to perform andrequires no pretreatment of sample, i. e., plasma and urine.The value can be obtained by fluorimeter and/or UV-visible spectrophotometer.The present method is sufficiently rapid and simple to make this a practical choice for many laboratories.展开更多
[Objectives]The content of total anthraquinone and 5 free anthraquinones in different processed products of rhubarb were determined.[Methods]Using emodin as the reference,the concentration of 1%magnesium acetate metha...[Objectives]The content of total anthraquinone and 5 free anthraquinones in different processed products of rhubarb were determined.[Methods]Using emodin as the reference,the concentration of 1%magnesium acetate methanol solution was used for color development,and the absorbance was measured at 516 nm wavelength;the mobile phase was methanol-0.1%phosphoric acid(76∶24)aqueous solution,the detection wavelength was set at 256 nm,the flow rate was 1.0 mL/min,the column temperature was 30℃,and the sample size was 10μL.[Results]The content of total anthraquinones in rhubarb was determined by UV spectrophotometry.The linear range was 0.98-23.52μg/mL,R2=0.9993,the average recoveries were 100.12%,99.66%and 99.15%,with RSDs of 1.58%,0.94%and 1.41%,respectively.The linear ranges of emodin,emodin,emodin,chrysophanol and emodin methyl ether were 0.0207-0.414(R2=0.9999),0.1721-3.442(R2=0.9996),0.0203-0.406(R2=0.9999),0.148-2.96(R2=0.9998)and 0.164-3.28(R2=0.9993),respectively.[Conclusions]The contents of total anthraquinones and free anthraquinones in different processed products of rhubarb were determined by UV spectrophotometry and HPLC.The method can be used for quality control of rhubarb and its different processed products.展开更多
[Objectives]To optimize the extraction process of total flavonoids from Eucommiae Cortex,establish the extraction and content determination methods of its medicinal materials,and study its in vitro antioxidant activit...[Objectives]To optimize the extraction process of total flavonoids from Eucommiae Cortex,establish the extraction and content determination methods of its medicinal materials,and study its in vitro antioxidant activity.[Methods]The total flavonoids from Eucommiae Cortex were extracted by reflux extraction method,and the effects of extraction method,extraction solvent concentration,extraction volume,and extraction time on the total flavonoids content of the medicinal materials were explored through the single factor experiment.Orthogonal experiment was carried out to optimize the extraction process conditions,and the optimal extraction process for total flavonoids from Eucommiae Cortex was screened out.The total antioxidant capacity index was used to determine the free radical scavenging ability of the total flavonoids from Eucommiae Cortex.[Results]The optimal extraction process of total flavonoids from Eucommiae Cortex was 50%ethanol,1∶40 solid-to-liquid-ratio,and 1.5 h reflux extraction time.Through the antioxidant experiment in vitro,it is found that the total flavonoids from Eucommiae Cortex have a higher scavenging ability for the total antioxidant capacity,and there is a certain positive correlation with the mass concentration of total flavonoids.[Conclusions]This method can effectively determine the total flavonoids content of Eucommiae Cortex medicinal material,and provide a certain scientific basis for the quality standard research of the medicinal material.The total flavonoids from Eucommiae Cortex have good in vitro antioxidant activity.And the method for extracting total flavonoids from Eucommiae Cortex medicinal material in this experiment has good repeatability,high stability and feasibility.展开更多
[Objectives]The research aimed to optimize extraction technology of total flavonoids from traditional Chinese medicine Yipichou,and establish methods of extraction and content determination of its medicinal materials....[Objectives]The research aimed to optimize extraction technology of total flavonoids from traditional Chinese medicine Yipichou,and establish methods of extraction and content determination of its medicinal materials.[Methods]Using reflux extraction method,total flavonoids of Yipichou were extracted.Via single-factor test,influence of extraction method,extraction solvent concentration,extraction volume and extraction time on content of total flavonoids from Yipichou was inspected.Using orthogonal test,extraction conditions were optimized,and optimal extraction technology of total flavonoids from Yipichou was obtained.[Results]The optimal extraction process of total flavonoids from Yipichou was as below:70%of methanol,1∶40 of solid-liquid ratio,and 1.0 h of reflux extraction time.[Conclusions]In the test,total flavonoids were extracted from Yipichou,with better repeatability,and stable and feasible method,which could provide certain scientific basis for studying quality standard of this medicinal material.展开更多
Purpose: The purpose of this study is to assess molecular interactions between several anticancer drugs and an iodinated contrast medium by Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible spect...Purpose: The purpose of this study is to assess molecular interactions between several anticancer drugs and an iodinated contrast medium by Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible spectroscopy (UV-Vis). Materials and Methods: Iopamidol (IPM) was used as an iodinated contrast medium, and mitomycin C (MTI), epirubicin hydrochloride (EPI), cisplatin (CDDP), 5-fluorouracil (5FU), irinotecan hydrochloride (CPT11), gemcitabine hydrochloride (dFdC), carboplatin (CBDCA), oxaliplatin (1OHP), paclitaxel hydrochloride (TAX) and docetaxel trihydrate (TXT) were used as anticancer drugs. For FT-IR, the purified IPM was mixed stoichiometrically with each anticancer drug as well as with a combination of MTI and EPI. After measuring each separated sample and the mixtures, the spectra of the mixtures were compared with the spectra of the sum of pure samples or the combination. For UV-Vis, IPM and anticancer drugs were dissolved in pure water;subsequently for the titration experiments, the mixtures were prepared by varying the molar ratio. IR absorption corresponds to stretching vibrations between atoms having covalent bonding, whereas UV-Vis spectra depend on molecular dynamics and shapes. Both UV-Vis and IR spectra change when there are molecular interactions such as aromatic ring stacking and hydrogen bonding. Result: IPM exhibited molecular interactions with MTI, EPI, CDDP, dFdC, CBDCA, 1OHP, TAX and TXT, as well as with the combination of MTI and EPI on FT-IR. However, molecular interactions were not observed on UV-Vis. Conclusion: Several anticancer drugs have molecular interactions with IPM, which could be clinically utilized for superselective intraarterial infusion chemotherapy.展开更多
[Objectives]To study and compare the processing methods of Ziziphus jujuba Mill.[Methods]Z.jujuba was processed by seven methods:cleaning,yellowish frying,burnt frying,carbonized frying,moistening by hot sand,steaming...[Objectives]To study and compare the processing methods of Ziziphus jujuba Mill.[Methods]Z.jujuba was processed by seven methods:cleaning,yellowish frying,burnt frying,carbonized frying,moistening by hot sand,steaming,and boiling.Ultraviolet-visible spectrophotometry was used to determine the content of total flavonoids in each processed Z.jujuba.[Results]The content of total flavonoids measured by various processing methods was different.The content of total flavonoids in the processed Z.jujuba by moistening by hot sand was relatively high and the absorption peak spectrum was almost the same as that of the cleaned processed Z.jujuba and the rutin reference substance.[Conclusions]The moistening by hot sand is the optimal method for processing of Z.jujuba.展开更多
At present, CuInSe2 (referred to as CIS) semiconductor has become one of the hot points in solar cell field at home and abroad for its excellent performances, such as direct bandgap, high light absorption coefficient,...At present, CuInSe2 (referred to as CIS) semiconductor has become one of the hot points in solar cell field at home and abroad for its excellent performances, such as direct bandgap, high light absorption coefficient, high photoelectric conversion efficiency and long-term stability. In this paper, the CIS bulk materials are prepared by the horizontal Bridgman method with double-heat sources, the crystal structure, microstructure morphology and composition of the samples are analyzed in X-ray diffraction instrument (XRD) and scanning electronic microscope (SEM) with Energy Dispersive X-ray Spectrum (EDX), and surface electrical state and electrical properties of the samples are characterized in X-ray photoelectron spectroscopy (XPS) and four point resistivity test system. The results show that the CIS crystal was grown, and that the conductive performance of the samples is good which display the characteristics of p-type semiconductor. Furthermore, a thin film CIS sample was obtained by argon ion-beam scanning bombardment, and it has high solar energy absorptivity and the bandgap of 0.99 eV analyzed in Ultraviolet-visible Spectrum that is suitable for solar cell. Keywords:展开更多
Paraquat and copper (Cu) are commonly used and detected in soil.Therefore,it is important to understand their mobility in the environment.In this study,the competitive effects of paraquat and Cu on their adsorption in...Paraquat and copper (Cu) are commonly used and detected in soil.Therefore,it is important to understand their mobility in the environment.In this study,the competitive effects of paraquat and Cu on their adsorption in five representative Chinese soils were investigated using batch adsorption equilibrium experiments and spectroscopic analysis.The results showed that the adsorption of paraquat in soil varied with soil type and was positively correlated with both soil cation exchange capacity and organic matter content.Paraquat exerted a more remarkable suppression effect on the adsorption of Cu than Cu on the adsorption of paraquat.In the presence of 0.12 and 0.19 mmol L-1paraquat,Cu adsorption decreased by 16%and 22%in Heilongjiang soil and by 24%and37%in Jiangxi soil,respectively.In the presence of 0.1 and 0.2 mmol L-1Cu,paraquat adsorption decreased by 4%and 8%in Heilongjiang soil and by15%and 19%in Jiangxi soil,respectively.Exchange selectivity involving symmetric cation (paraquat2+and Cu2+) exchange is the probable basis for the suppression effect.The ultraviolet-visible absorption experiments suggested that the formation of Cu-paraquat complexes was unlikely to happen in a solution or at the soil surface.Copper K-edge X-ray absorption spectroscopy indicated that Cu in soil may have some water as hydration layers as the nearest neighbors,and each Cu atom was coordinated with five oxygen atoms.These findings greatly improve our knowledge of the molecular-scale adsorption mechanisms of paraquat and Cu in soil and can be used to predict the behavior,transport,and fate of paraquat and Cu in agricultural soils.展开更多
基金the University of Greenwich for financial support
文摘The effects of temperature,pH and long-term storage on the secondary structure and conformation changes of bovine haemoglobin（bHb） were studied using circular dichroism（CD） and ultraviolet-visible（UV-vis） spectroscopies.Neural network software was used to deconvolute the CD data to obtain the fractional content of the five secondary structures.The storage stability of bHb solutions in pH 6,7 and8 buffers was significantly higher at 4 ℃ than at 23 ℃ for the first 3 days.A complete denaturation of bHb was observed after 40 days irrespective of storage temperature or pH.The bHb solutions were also exposed to heating and cooling cycles between 25 and 65 ℃ and structural changes were followed by UVvis and CD spectroscopies.These experiments demonstrated that α-helix content of bHb decreased steadily with the increasing temperature above 35 ℃ at all pH values.The loss in a-helicity and gain in random coil conformations was pH-dependent and the greatest under alkaline conditions.Furthermore,there was minimal recovery of the secondary structure content upon cooling to 25 ℃.The use of bHb as a model drug is very common and this study elucidates the significance of storage and processing conditions on its stability.
文摘In order to differentiate regions, varieties, and parts of tobacco leaves, two pattern recognition methods through pattern classification modeling were developed based on the comprehensive information of ultraviolet-visible spectroscopy （UV-VIS） by employing one-way analysis of variance （ANOVA1） and wave range random combination （WRRC） technology from MATLAB. This proposed classification method has never been reported previously and the instrument and operation for this method is much more convenient and efficient than previous reported classification methods. The result of this paper demonstrated that the spectral features extracted by ANOVAI and WRRC methods could be used to differentiate tobacco leaves with different patterns. The ANOVAI method had a training recognition rate range of 75.00-87.50%,4 and a validation recognition rate range of 57.14-100%. The WRRC method had a training recognition rate range of 75.00-94.12% and a validation recognition rate range of 66.67-100%. The ANOVAI method is more convenient and efficient in model developing, while the WRRC method utilizes fewer model variables and is more robust.
文摘Phosphorus fertilizers from less pure sedimentary sources become increasingly important, due to depletion of phosphorus from igneous rock of high quality. Consequently, robust methods with potential to remove various types of hazardous elements are required. Among such impurities, hexavalent chromium (Cr(VI)) is very likely to become a future challenge. Different industrial ways to treat phosphate rock are currently being practised, and we have here studied how chromium behaves when using the nitro-phosphate process. The reduction mechanism of Cr (VI) in nitric acid and phosphoric acid solutions was investigated by measuring redox potential and UV-VIS spectra. The results show that Cr (VI) is not stable in strong nitric acid solutions. Reduction of Cr (VI) species decreased with decreasing temperature, NO<sub>2</sub> concentration, ionic strength and absence of light. These findings support the proposed reduction reaction:The reduction rate was observed proportional to the nitric acid decomposition: .
基金supported by National Natural Science Foundation of China(Nos.62027818,61874034,and 51861135105)Natural Science Foundation of Shanghai(No.18ZR1405000)Shanghai Science and Technology Innovation Program(No.19520711500).
文摘In this work,we reported a high-performance-based ultraviolet-visible(UV-VIS)photodetector based on a TiO_(2)@GaO_(x)N_(y)-Ag heterostructure.Ag particles were introduced into TiO_(2)@GaO_(x)N_(y)to enhance the visible light detection perfor-mance of the heterojunction device.At 380 nm,the responsivity and detectivity of TiO_(2)@GaO_(x)N_(y)-Ag were 0.94 A/W and 4.79×109 Jones,respectively,and they increased to 2.86 A/W and 7.96×1010 Jones at 580 nm.The rise and fall times of the response were 0.19/0.23 and 0.50/0.57 s,respectively.Uniquely,at 580 nm,the responsivity of fabricated devices is one to four orders of magnitude higher than that of the photodetectors based on TiO_(2),Ga_(2)O_(3),and other heterojunctions.The excellent optoelectronic characteristics of the TiO_(2)@GaO_(x)N_(y)-Ag heterojunction device could be mainly attributed to the synergistic effect of the type-Ⅱband structure of the metal-semiconductor-metal heterojunction and the plasmon resonance effect of Ag,which not only effectively promotes the separation of photogenerated carriers but also reduces the recombination rate.It is fur-ther illuminated by finite difference time domain method(FDTD)simulation and photoelectric measurements.The TiO_(2)@GaO_(x)N_(y)-Ag arrays with high-efficiency detection are suitable candidates for applications in energy-saving communica-tion,imaging,and sensing networks.
基金supported by the earmarked fund for China Agriculture Research System (2013–2017)the Chinese Outstanding Talents Program in Agricultural Sciences
文摘Dissolved organic matter(DOM) plays important roles in soil biogeochemistry activity and nutrients transportation in soils, but studies regarding the long-term effects of green manures on the content and structure of DOM in red paddy soil have not been reported yet. A long-term green manure experiment established in 1982 was utilized to test the DOM contents in different treatments, and the spectral characteristics of DOM were investigated by using ultraviolet-visible(UV-Vis) spectrometry and Fourier transform infrared(FTIR) spectrometry. The experiment included four cropping systems: ricerice-milk vetch(RRV), rice-rice-rape(RRP), rice-rice-ryegrass(RRG) and rice-rice-winter fallow(RRF), among them, milk vetch, rape, and ryegrass are popular winter green manure species in southern China. The results showed that the content of dissolved organic carbon(DOC), which is widely used to estimate the concentration of DOM, was significantly promoted after the incorporation of green manures compared with the other sampling stages. The contents of aromatic groups and the degree of humification of DOM increased in RRV and RRP, suggesting more complex compositions of the soil DOM after long-term application of milk vetch and rape. The contents of phenol, alcohol and carboxylic acid group at the mature stage of early rice were significantly higher than those at the stage of after green manures turned over, especially for the RRV treatment. The absorption ratio of FTIR indicated that winter plantation of rape increased the aromatic-C/aliphatic-C ratio, and ryegrass increased the aromatic-C/carboxyl-C ratio. In conclusion, long-term planting of milk vetch and rape as green manures increased the degree of aromaticity, humification and average molecular weight of DOM, and made the DOM more stable in red paddy soil.
文摘The metal contents of Nigerian coal minerals were analyzed using an atomic absorption spectrophotometer. Calcium, Na, and Fe occurred as the major elements with concentrations ranging from 9 782 μg/g for Ca to 432 μg/g for Na whereas K, Mg, Mn, Ni, Cr, Zn, Pb, and Cu, which occurred at trace levels ranged from 673.73 μg/g for Mg to 2.97 μg/g for Mn. The results of the quantitative analysis of porphyrins extracted from the coal minerals showed that Onyeama coal has the highest amount of porphyrins (ca～0.96 μg/g) while Okpara has the lowest (ca～0.30 μg/g). The porphyrins were qualitatively characterized by a combination of thin layer chromatography (TLC), infrared, and ultraviolet-visible spectrophotometers. The results of the mid infrared analysis (MIR) showed the presence of absorption bands at 3 440 cm～1～3 450 cm-1 and 1 640 cm-1～1 680 cm-1 , which are owing to the stretching vibrations of N ─ H and C─ C of aromatics, with C─ H out of plane (oop) bending vibrations at wavenumbers less than 900 cm-1, all of which are characteristic absorptions of porphyrin free base. The ultraviolet-visible data showed prominent peaks at ～400 nm(Soret band) and at wavelength ranges of 535 nm～550 nm(β-band) and 565 nm～ 600 nm (α-band) for the coal porphyrins analyzed. The geochemical significance of the metals and porphyrins in coal minerals are discussed.
基金Supported by the National Natural Science Foundation of China(Nos.20773044,20873050,20921003 and 20973074)the "111" Project of Minstry of Education of China(No.B06009)
文摘Fourier-transform infrared（FTIR）,Raman and ultraviolet-visible spectra of 4,4＇-bipyridine and its me-tal-organic coordination compounds synthesized from 4,4＇-bipyridine and nitrate of Co（Ⅱ）,Ni（Ⅱ） and Zn（Ⅱ） were measured and analyzed,respectively.The main FTIR and Raman bands were assigned in detail.The relationship between these characteristic bands and the structure of ligands and coordination compounds were discussed.
基金supported by the Assistant Secretary for Energy Efficiency and Renewable Energy,Vehicle Technologies Office,under the Advanced Battery Materials Research(BMR)Program of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231support by the U.S.Department of Energy under Contract No.106298-001+2 种基金the funding from Polish Ministry of Science and Higher Education No.1670/MOB/V/2017/0funding support of SUSTechthe resources of the National Energy Research Scientific Computing Center(NERSC)that is supported by the Office of Science of the U.S.Department of Energy。
文摘The lithium-sulfur(Li-S)battery is one of the most promising substitutes for current energy storage systems because of its low cost,high theoretical capacity,and high energy density.However,the high solubility of intermediate products(i.e.,lithium polysulfides)and the resultant shuttle effect lead to rapidly fading capacity and a low coulombic efficiency,which hinder the practical application of Li-S batteries.In this study,block copolymers are constructed with both an ethylene oxide unit and a styrene unit and then used as binders for Li-S batteries.Electrochemical performance improvements are attributed to the synergistic effects contributed by the different units of the block copolymer.The ethylene oxide unit traps polysulfide,which bonds strongly with the intermediate lithium polysulfide,and enhances the transport of lithium ions to reach high capacity.Meanwhile,the styrene unit maintains cathode integrity by improving the mechanical properties and elasticity of the constructed block copolymer to accommodate the large volume changes.By enabling multiple functions via different units in the polymer chain,high sulfur utilization is achieved,polysulfide diffusion is confined,and the shuttle effect is suppressed during the cycle life of Li-S batteries,as revealed by operando ultraviolet-visible spectroscopy and S Kedge X-ray absorption spectroscopy.
基金Project(10JJ5057)supported by the Hunan Provincial Natural Science Foundation of China
文摘Stable and monodispersed silver nanoparticles were produced through a mild,convenient,one-pot method based on the reduction of silver nitrate in the presence of poly(amic acid) (PAA) as a stabilizer.The surface plasma band transition was monitored along with time in the reaction mixture for three sets of experiments by ultraviolet-visible spectroscopy.Analysis of the data with the Avrami equation yielded n exponent with values between 0.5 and 1.5,demonstrating three-dimensional heterogeneous nucleation and diffusion-controlled growth,accompanied by soft impingement effect.XRD and TEM analyses show a softly agglomerated polycrystalline state and a nearly spherical morphology (<50 nm) of nanoparticles.The FT-IR result indicates that the PAA molecular structure could be hardly influenced by the formation of nanoparticles.
基金Supported by the National Natural Science Foundation of China(No.10974067)the Natural Science Foundation of Jilin Province,China(No.20101508)the Technology Development Projects of Jilin Province,China(No.20090534)
文摘Raman spectra and ultraviolet-visible（UV-Vis） absorption spectra of linear polyene molecule-canthaxan-thin in n-hexane are measured and analyzed.In addition,the optimized structure of canthaxanthin was calculated via density functional theory（DFT） functional B3LYP.With decreasing the concentration,Raman scattering cross section （RSCS） of fundamental frequency is extremely high,and the UV-Vis absorption bands become narrower.The results of coherent weakly damped electron-Lattice vibration model were analyzed.
文摘New Schiff base polymers poly[4,4＇-methylenebis（cinnamaldehyde）ethylenediimine] （PMBCen）, poly[4,4＇- methylenebis（cinnamaldehyde）1,2-propylenediimine] （PMBCPn）, poly[4,4＇-methylenebis（cinnamaldehyde）1,3-propylenediimine] （PMBCPR）, poly[4,4＇-methylenebis（cinnamaldehyde） 1,2-phenylenediimine] （PMBCPh）, poly[4,4＇-methylenebis（cinnamaldehyde）meso-stilbenediimine] （PMBCS）, poly[4,4＇-methylenebis（cinnamaldehyde）urea] （PMBCUR）, poly[4,4＇- methylenebis（cinnamaldehyde）semicarbazone] （PMBCSc）, poly[4,4＇-methylenebis（cinnamaldehyde）thiosemicarbazone] （PMBCTSc） and poly[4,4＇-methylenebis（cinnamaldehyde）hydrazone] （PMBCH） were formed by polycondensation of 4,4＇- methylenebis（cinnamaldehyde） with ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,2-phenylenediamine, meso-stilbenediamine, urea, semicarbazide, thiosemicarbazide and hydrazine, respectively. The dialdehyde and polymers have been characterized through elemental micro-analysis, IR, UV-Vis and ^1H-NMR spectroscopic techniques. Thermoanalytical studies and viscous flow of dilute solutions of dialdehyde and its polymers have been examined and compared.
基金ACKNOWLEDGMENTS This work was supported by the Program for New Century Excellent Talents in University, the Science and Technology Foundation for Young Scholars in Sichuan Province, and the National Natural Science Foundation of China （No.10774104）.
文摘Urea L-malic acid, a new second order nonlinear optical crystal, was studied using density functional theory （DFT）. PBEPBE/6-31＋G（d,p） method, the optimal method for comparing the results from the several DFT methods, was chosen to study the molecular structure. Infrared and ultraviolet-visible spectra were obtained and compared with experiments. The ultraviolet-visible spectrum was also analyzed by the molecular orbital population. The geometries, and the infrared and ultraviolet-visible spectra in water were studied using DFT methods in combination with the polarized continuum model to predict the perturbations by the solvent effect.
文摘The increasing importance of endothelium-derived relaxing factor(EDRF),which has now been identified as nitric oxide (NO),has been underscored by the eltlcidation of its role'in a growing number of normal and pathophysiological processes. Therefore techniques for detection of nitric oxide should serve as useful tools in defining the role of nitric oxide to these processes.We have improved a simple, sensitive assay methods for determination of nitric oxide in blood, tissue, and other body fluids both by fluorometric and by ultraviolet-visible spectrophotometric measurements. Data obtained by floores cence and by UV-visible assay were correlated well (r=0. 9938, P<0. 0001 ).Linearity:0.1￣ 100μmol/L,r =0.9996,P<0.0001. The minimum detection limit were < 10pmol/L. Within-and between-run CVs were 2. 48%and 4. 62% (n = 10),respectively.Reference values for healthy adults(n=40) were(9.82 ± 1. 57) pmol/L. In conclusion:the methods is sensitive, specific,and precise. It is fairly rapid and simple to perform andrequires no pretreatment of sample, i. e., plasma and urine.The value can be obtained by fluorimeter and/or UV-visible spectrophotometer.The present method is sufficiently rapid and simple to make this a practical choice for many laboratories.
基金the Training Project of National Traditional Chinese Medicine Characteristic Technology Inheritance Talents(T20184828005,201548160100).
文摘[Objectives]The content of total anthraquinone and 5 free anthraquinones in different processed products of rhubarb were determined.[Methods]Using emodin as the reference,the concentration of 1%magnesium acetate methanol solution was used for color development,and the absorbance was measured at 516 nm wavelength;the mobile phase was methanol-0.1%phosphoric acid(76∶24)aqueous solution,the detection wavelength was set at 256 nm,the flow rate was 1.0 mL/min,the column temperature was 30℃,and the sample size was 10μL.[Results]The content of total anthraquinones in rhubarb was determined by UV spectrophotometry.The linear range was 0.98-23.52μg/mL,R2=0.9993,the average recoveries were 100.12%,99.66%and 99.15%,with RSDs of 1.58%,0.94%and 1.41%,respectively.The linear ranges of emodin,emodin,emodin,chrysophanol and emodin methyl ether were 0.0207-0.414(R2=0.9999),0.1721-3.442(R2=0.9996),0.0203-0.406(R2=0.9999),0.148-2.96(R2=0.9998)and 0.164-3.28(R2=0.9993),respectively.[Conclusions]The contents of total anthraquinones and free anthraquinones in different processed products of rhubarb were determined by UV spectrophotometry and HPLC.The method can be used for quality control of rhubarb and its different processed products.
基金Supported by Special Project for Central Leading Local Science and Technology Development in Sichuan Province:Southwestern Characteristic Chinese Medicine Resources Genetics Innovation Platform(2020ZYD058)Young Teachers Enhancement Project of Guangxi Department of Education in 2018(2018KY0300)2019-2021 Guangxi First-class Discipline Construction Open Project Fund for Young Scholars of Guangxi University of Chinese Medicine(2019XK089).
文摘[Objectives]To optimize the extraction process of total flavonoids from Eucommiae Cortex,establish the extraction and content determination methods of its medicinal materials,and study its in vitro antioxidant activity.[Methods]The total flavonoids from Eucommiae Cortex were extracted by reflux extraction method,and the effects of extraction method,extraction solvent concentration,extraction volume,and extraction time on the total flavonoids content of the medicinal materials were explored through the single factor experiment.Orthogonal experiment was carried out to optimize the extraction process conditions,and the optimal extraction process for total flavonoids from Eucommiae Cortex was screened out.The total antioxidant capacity index was used to determine the free radical scavenging ability of the total flavonoids from Eucommiae Cortex.[Results]The optimal extraction process of total flavonoids from Eucommiae Cortex was 50%ethanol,1∶40 solid-to-liquid-ratio,and 1.5 h reflux extraction time.Through the antioxidant experiment in vitro,it is found that the total flavonoids from Eucommiae Cortex have a higher scavenging ability for the total antioxidant capacity,and there is a certain positive correlation with the mass concentration of total flavonoids.[Conclusions]This method can effectively determine the total flavonoids content of Eucommiae Cortex medicinal material,and provide a certain scientific basis for the quality standard research of the medicinal material.The total flavonoids from Eucommiae Cortex have good in vitro antioxidant activity.And the method for extracting total flavonoids from Eucommiae Cortex medicinal material in this experiment has good repeatability,high stability and feasibility.
基金Supported by Preparation Quality Improvement Project of Zhuang and Yao Medicine Hospital,Administration of Traditional Chinese Medicine,Guangxi Zhuang Autonomous Region(GZZJ202013,GZZJ202015)Project of Improving the Basic Scientific Research Ability of Young and Middle-aged Teachers in Guangxi Colleges and Universities in 2019(2019KY0341)+2 种基金Opening Project of Guangxi Zhuang and Yao Medicine Key Laboratory(GXZYKF2020A-08)Research Project of Guangxi International Zhuang Medicine Hospital in 2020(GZ202001)Youth Fund Project of Guangxi University of Chinese Medicine in 2019(2019QN036).
文摘[Objectives]The research aimed to optimize extraction technology of total flavonoids from traditional Chinese medicine Yipichou,and establish methods of extraction and content determination of its medicinal materials.[Methods]Using reflux extraction method,total flavonoids of Yipichou were extracted.Via single-factor test,influence of extraction method,extraction solvent concentration,extraction volume and extraction time on content of total flavonoids from Yipichou was inspected.Using orthogonal test,extraction conditions were optimized,and optimal extraction technology of total flavonoids from Yipichou was obtained.[Results]The optimal extraction process of total flavonoids from Yipichou was as below:70%of methanol,1∶40 of solid-liquid ratio,and 1.0 h of reflux extraction time.[Conclusions]In the test,total flavonoids were extracted from Yipichou,with better repeatability,and stable and feasible method,which could provide certain scientific basis for studying quality standard of this medicinal material.
文摘Purpose: The purpose of this study is to assess molecular interactions between several anticancer drugs and an iodinated contrast medium by Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible spectroscopy (UV-Vis). Materials and Methods: Iopamidol (IPM) was used as an iodinated contrast medium, and mitomycin C (MTI), epirubicin hydrochloride (EPI), cisplatin (CDDP), 5-fluorouracil (5FU), irinotecan hydrochloride (CPT11), gemcitabine hydrochloride (dFdC), carboplatin (CBDCA), oxaliplatin (1OHP), paclitaxel hydrochloride (TAX) and docetaxel trihydrate (TXT) were used as anticancer drugs. For FT-IR, the purified IPM was mixed stoichiometrically with each anticancer drug as well as with a combination of MTI and EPI. After measuring each separated sample and the mixtures, the spectra of the mixtures were compared with the spectra of the sum of pure samples or the combination. For UV-Vis, IPM and anticancer drugs were dissolved in pure water;subsequently for the titration experiments, the mixtures were prepared by varying the molar ratio. IR absorption corresponds to stretching vibrations between atoms having covalent bonding, whereas UV-Vis spectra depend on molecular dynamics and shapes. Both UV-Vis and IR spectra change when there are molecular interactions such as aromatic ring stacking and hydrogen bonding. Result: IPM exhibited molecular interactions with MTI, EPI, CDDP, dFdC, CBDCA, 1OHP, TAX and TXT, as well as with the combination of MTI and EPI on FT-IR. However, molecular interactions were not observed on UV-Vis. Conclusion: Several anticancer drugs have molecular interactions with IPM, which could be clinically utilized for superselective intraarterial infusion chemotherapy.
基金Supported by Scientific Research Foundation of Yunnan Provincial Department of Education(2018JS719).
文摘[Objectives]To study and compare the processing methods of Ziziphus jujuba Mill.[Methods]Z.jujuba was processed by seven methods:cleaning,yellowish frying,burnt frying,carbonized frying,moistening by hot sand,steaming,and boiling.Ultraviolet-visible spectrophotometry was used to determine the content of total flavonoids in each processed Z.jujuba.[Results]The content of total flavonoids measured by various processing methods was different.The content of total flavonoids in the processed Z.jujuba by moistening by hot sand was relatively high and the absorption peak spectrum was almost the same as that of the cleaned processed Z.jujuba and the rutin reference substance.[Conclusions]The moistening by hot sand is the optimal method for processing of Z.jujuba.
文摘At present, CuInSe2 (referred to as CIS) semiconductor has become one of the hot points in solar cell field at home and abroad for its excellent performances, such as direct bandgap, high light absorption coefficient, high photoelectric conversion efficiency and long-term stability. In this paper, the CIS bulk materials are prepared by the horizontal Bridgman method with double-heat sources, the crystal structure, microstructure morphology and composition of the samples are analyzed in X-ray diffraction instrument (XRD) and scanning electronic microscope (SEM) with Energy Dispersive X-ray Spectrum (EDX), and surface electrical state and electrical properties of the samples are characterized in X-ray photoelectron spectroscopy (XPS) and four point resistivity test system. The results show that the CIS crystal was grown, and that the conductive performance of the samples is good which display the characteristics of p-type semiconductor. Furthermore, a thin film CIS sample was obtained by argon ion-beam scanning bombardment, and it has high solar energy absorptivity and the bandgap of 0.99 eV analyzed in Ultraviolet-visible Spectrum that is suitable for solar cell. Keywords:
文摘Paraquat and copper (Cu) are commonly used and detected in soil.Therefore,it is important to understand their mobility in the environment.In this study,the competitive effects of paraquat and Cu on their adsorption in five representative Chinese soils were investigated using batch adsorption equilibrium experiments and spectroscopic analysis.The results showed that the adsorption of paraquat in soil varied with soil type and was positively correlated with both soil cation exchange capacity and organic matter content.Paraquat exerted a more remarkable suppression effect on the adsorption of Cu than Cu on the adsorption of paraquat.In the presence of 0.12 and 0.19 mmol L-1paraquat,Cu adsorption decreased by 16%and 22%in Heilongjiang soil and by 24%and37%in Jiangxi soil,respectively.In the presence of 0.1 and 0.2 mmol L-1Cu,paraquat adsorption decreased by 4%and 8%in Heilongjiang soil and by15%and 19%in Jiangxi soil,respectively.Exchange selectivity involving symmetric cation (paraquat2+and Cu2+) exchange is the probable basis for the suppression effect.The ultraviolet-visible absorption experiments suggested that the formation of Cu-paraquat complexes was unlikely to happen in a solution or at the soil surface.Copper K-edge X-ray absorption spectroscopy indicated that Cu in soil may have some water as hydration layers as the nearest neighbors,and each Cu atom was coordinated with five oxygen atoms.These findings greatly improve our knowledge of the molecular-scale adsorption mechanisms of paraquat and Cu in soil and can be used to predict the behavior,transport,and fate of paraquat and Cu in agricultural soils.
