Decabromodiphenyl ethane(DBDPE)is widely used as an additive flame retardant and has led to global pollution.Its has a large molecular mass and is prone to debromination and degradation under photothermal conditions,r...Decabromodiphenyl ethane(DBDPE)is widely used as an additive flame retardant and has led to global pollution.Its has a large molecular mass and is prone to debromination and degradation under photothermal conditions,resulting in smaller homologous compounds.Due to the lack of standard substances for debromination products,the in-depth study of DBDPE environmental geochemical behavior through debromination conversion has been hindered.Therefore,based on DBDPE photodegradation experiment,this study first analyzed and identified the brominated products of DBDPE using high-performance liquid chromatography-atmospheric pressure photoionization-time of flight mass spectrometry(HPLC-APPI-TOF/MS).Four debromination products-nonabromodiphenyl ethane(nonaBDPE),octabromodiphenyl ethane(octa-BDPE),heptabromodiphenyl ethane(hepta-BDPE)and hexabromodiphenyl ethane(hexa-BDPE)are identified based on the characteristic ion peak of[M-Br+O]^(-) in negative ion mode.Subsequently,using methanol as the mobile phase,four debromination products of DBDPE were separated and purified with a semi-preparative high-performance liquid chromatography(SP-HPLC)system equipped with an Agilent Zorbax Eclipse PAH column(4.6 mm×250 mm,5μm).The first-time acquisition of hexa-BDPE(60.00μg),octa-BDPE(19.40μg),hepta-BDPE(31.20μg)and octa-BDPE(isomer,45.20μg)with purity exceeding 90%has been achieved.Among them,the purity of one hepta-BDPE monomer is as high as 98.91%.This study indicates that based on photodegradation experiments,the combination of HPLC-APPI-TOF/MS and SP-HPLC techniques can rapidly identify and prepare DBDPE debrominated products.This approach meets the requirements for preliminary research on the pollution characteristics of DBDPE debrominated compounds and offers a feasible solution for the preparation of standard reference materials for emerging pollutants.展开更多
The aim of this study was to rapidly isolate the major effective flavanoids from the extract of safflower（Carthamus tinctorius） using ODS medium pressure liquid chromatography（MPLC） and semi-preparative HPLC, guid...The aim of this study was to rapidly isolate the major effective flavanoids from the extract of safflower（Carthamus tinctorius） using ODS medium pressure liquid chromatography（MPLC） and semi-preparative HPLC, guided by a developed fingerprint. Twelve compounds were isolated and their structures were elucidated as kaempferol 3-O-β-D-rutinoside（1）, kaempferol 3-O-β-D-glucoside（2）, rutin（3）, quercetin 3-O-β-D-glucoside（4）, 6-hydroxykaempferol 3,6,7-tri-O-β-D-glucoside（5）, 6-hydroxykaempferol 3-O-β-D-glucoside（6）, 6-hydroxykaempferol 6,7-di-O-β-D-glucoside（7）, 6-hydroxykaempferol 3-O-β-Drutinoside（8）, 6-hydroxykaempferol 3,6-di-O-β-D-glucosyl 7-O-β-D-glucuronide（9）, isosafflomin C（10）, safflomin C（11） and hydroxysafflor yellow A（12） by spectroscopic analysis and comparing with the literature. Our results demonstrated that preparative pressurized liquid chromatography combined with HPLC fingerprint guide is an efficient tool to isolate the target compounds quickly.展开更多
It has been found that samples of sodium aluminate solutions with the same composition but different preparative history may have difTerent structure and physico-chemical properties.The structure of sodium-bearing alu...It has been found that samples of sodium aluminate solutions with the same composition but different preparative history may have difTerent structure and physico-chemical properties.The structure of sodium-bearing aluminate solutions change very slowly during the storage after preparation.Sodium aluminate solutions contain several ammunium-bearing anisons such as Al(OH)^(-)_(4),Al(OH)^(3-)_(6)and[(HO)_(3)Al-O-Al(OH)_(3)]^(2-),etc.These anions can convert to each other but the reactions are very slow owing to the formation or breakage of covalent Al-O bond.Hence the ratio between these anions approaches equilibrium very slowly after the preparation,and the structure or properties of these solution samples before equilibrium is reached depend on their preparative histosive.展开更多
1.IntroductionSodium aluminate solutions are veryimportant intermediate products in alumin-ium metallurgy.The physico-chemicalproperties of sodium aluminate solutions areconcerned by metallurgists and engineersdealing...1.IntroductionSodium aluminate solutions are veryimportant intermediate products in alumin-ium metallurgy.The physico-chemicalproperties of sodium aluminate solutions areconcerned by metallurgists and engineersdealing with alumina production[1].Thedata of viscosity,electroconductivity,UV展开更多
In this paper a simple preparative method for isolation and purification of ginkgolides A and B was developed,As starting material,a commercially available standardized ginkgo extract (EGb761,containing 24% flavonoid ...In this paper a simple preparative method for isolation and purification of ginkgolides A and B was developed,As starting material,a commercially available standardized ginkgo extract (EGb761,containing 24% flavonoid and 6% terpene trilactones) was used,After a pretreatment step,optimized by the uniform design method ,the concentrated intermediate extract with high content of GA and gb(+90%) was separated into the individual terpenes by preparative liquid chromatography eluted with petroleum ether-ethylacetate,Analysis of products was carried out by means of HPLC-ELSD(evaporative light -scattering detector),The results show that ginkgolides A and B are obtained in higher yield and better purity.展开更多
An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro-matog...An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro-matography(HPLC) and solid-phase extraction(SPE). The aim of this study was to obtain an effective method with high preparative efficiency and importantly to avoid the transformation of unstable compounds. The preparative HPLC system was based on an LC/MS controlled four-channel autopurification system. The SPE method was performed with a C18 packing material to trap the target compounds and to remove the acidic additive derived from the mobile phase. Using this method, the unstable iridoid glucosides(IGs) as model compounds were successfully isolated and purified from the extract of Hedyotis diffusa Willd. Six IGs(including one new minor IG) and one nucleotide compound were simultaneously obtained, each with a purity of 91% as determined by HPLC. The structures of the isolated compounds were identified by UPLC/Q-TOF MS, UV, 1D and/or 2D NMR. It was demonstrated that the combination of preparative HPLC with SPE is a versatile tool for preparative purification of unstable compounds from complex natural products.展开更多
Gatifloxacin （GFX） is a kind of chiral fluoroquinolones compound due to the methyl group at the C-3 position of the piperazine ring[1]. Although the enantiomers of GFX show similar levels of antimicrobial activity a...Gatifloxacin （GFX） is a kind of chiral fluoroquinolones compound due to the methyl group at the C-3 position of the piperazine ring[1]. Although the enantiomers of GFX show similar levels of antimicrobial activity and pharmacokinetics[2], the other biological activities （i.e., toxicity or enantioselective recognition to various receptors in vivo） of GFX enantiomers have not yet been studied. With this in mind, we developed a rapid and cost-effective high performance liquid chromatographic （HPLC） separation procedure for GFX enantiomers with a pre-column esterification strategy.展开更多
A liquid phase chemical bath deposition(LPCBD)method for deposition of PbS thin films is presented.The growth kinetics and reaction mechanism have been discussed.For the deposition,triethanolamine complex of lead acet...A liquid phase chemical bath deposition(LPCBD)method for deposition of PbS thin films is presented.The growth kinetics and reaction mechanism have been discussed.For the deposition,triethanolamine complex of lead acetate was allowed to react with aqueous thiourea solution.Glass micro-slides were used as the substrates.The deposition of PbS films was carried out under different growth parameters such as temperature,time,and reaction pH.The growth rate,under different conditions,was measured in terms of a terminal layer thickness and the possible reaction kinetics and mechanism is discussed.The optimum values of the parameters to produce good quality films are 60 min,80℃and 10.5±0.1.An EDS analysis showed that the film stoichiometry is dependent on the reaction pH and the films tend to be almost stoichiometric in high alkaline environment(>10.5).The PbS deposits appeared smooth,tightly adherent,uniform and reflecting with blackish-grey colour.The XRD studies showed crystalline cubic type of structure with preferred orientation along(200)plane.The calculated d-values,intensities of reflections and lattice parameter have excellent match with that of the JCPD data.The crystallite size is found to be few tens of nanometer.The surface morphology revealed by SEM showed that the crystallites are randomly oriented and are of different shapes and sizes.Majority of the crystallites appeared smaller and spherical in shape whereas,growth of some elongated irregular crystallites;bit larger in size and differing in shapes,have also been favoured.展开更多
Birnessite occurs in a wide variety of natural environments, and plays animportant role in soil chemistry. A modified Staehli procedure was used to synthesize sodiumbirnessite in an alkali medium by O_2 oxidation. The...Birnessite occurs in a wide variety of natural environments, and plays animportant role in soil chemistry. A modified Staehli procedure was used to synthesize sodiumbirnessite in an alkali medium by O_2 oxidation. The effects of preparative parameters on thesynthesis of birnessite, such as pretreatment on solutions with N2, reaction temperature, O_2 flowrate, fluxion velocity of the reaction suspension, and dehydration conditions were investigated. Thefluxion velocity of the reactive suspension and O_2 flow rate significantly influenced thesynthesis of birnessite. Vigorous stirring raised the fluxion velocity of the reaction suspensionand easily allowed synthesis of pure crystalline birnessite. However pretreatment of the reactingsolutions with N_2 and the reaction temperature had little effect on the synthesis. Diffusion of O_2was the controlling step during the course of oxidation. The optimum synthetic conditions for purebirnessite were: a NaOH to Mn molar ratio of 13.7, an O_2 flow rate of 2 L min^(-1), and oxidationfor 5 hours with vigorous stirring at normal temperatures. The chemical composition of thesynthesized pure birnessite was Na_(0.25)MnO_(2.07)·0.66H_2O.展开更多
Monodispersed potymeric microparticles were prepared by seed-poly- merization.High performance packings were obtained for anion chromatography by coating the surface-sutfonated partictes with quarternized latexes.
Although mechanism of symbiosis between arbuscular mycorrhizal fungi (AMF) and host plants has been investigated by genetic analysis, very little knowledge has been obtained because genome analysis of AMF is not perfe...Although mechanism of symbiosis between arbuscular mycorrhizal fungi (AMF) and host plants has been investigated by genetic analysis, very little knowledge has been obtained because genome analysis of AMF is not perfect yet. Thus, we tried to develop mass purification of proteins using preparative chromatography in order to accelerate roteomic analysis of proteins related to mycorrhizal symbiosis, such as 24 and 53 kDa proteins. In particular, our data showed that 53 kDa proteins would be restrictively expressed when mycorrhizal fungi and host plants were stressed. However, 24 kDa proteins, which appear to be a usable indicator for the existence of various my-corrhizal fungi, were habitually detected in not only AMF but also other mycorrhizal fungi such as ectomycorrhizal fungi (EF). Moreover, we discovered new preparative chromatographical techniques for isolation and mass purification of those proteins. We are convinced that this chromato-graphical technique will greatly contribute to proteomic approach of mycorrhizal symbiosis.展开更多
This paper carried out a comparative analysis of different types of electrophoretic systems which were used for the analysis of casein complex from cow milk (polyacrylamide gel electrophoresis: for the neutral and aci...This paper carried out a comparative analysis of different types of electrophoretic systems which were used for the analysis of casein complex from cow milk (polyacrylamide gel electrophoresis: for the neutral and acidic native conditions, in gradient variant, the presence of sodium dodecyl sulphate or with including urea). Taking into attention the separation efficiency, complexity of electrophoretic system, the impact of system components, we have selected the anode system of the homogeneous gel in the presence of urea as the basis for the preparation of casein fractions. It also changed the composition and the structure of the electrophoretic apparatus. The changes allow purification of casein fractions up to several grams during one stage of treatment (for 5 hours). The purified casein fractions were tested for the homogeneity and have been recommended for using in the biomedical researches, including the processes of the formation of the bioactive peptides.展开更多
The renaturation and purification of recombinant human proinsulin (rh-proinsulin) expressed in E. coli with the unit of simultaneous renaturation and purification of protein (USRPP) in semi-preparative scale was studi...The renaturation and purification of recombinant human proinsulin (rh-proinsulin) expressed in E. coli with the unit of simultaneous renaturation and purification of protein (USRPP) in semi-preparative scale was studied. The result shows that rh-proinsulin extracted with 8.0 mol/L urea can be renatured and purified simultaneously in 45 minutes with the USRPP (1050 mm ID). The purity of rh-proinsulin was found to be more than 90% and the mass recovery to be more than 80%. The renaturation effect of rh-proinsulin with the USRPP was tested by enzyme cleavage for obtaining insulin. In addition, the result was further confirmed with RPLC, SDS-PAGE electrophoresis, and MALDI-TOF, respectively.展开更多
A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex ...A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex Havil(UR)were chosen to show the advantage of this method.The sample enrichment and separation were展开更多
A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonall...A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonally pulsed electric fields of significantly different magnitudes are applied to a microchip filled with a sieving matrix of 1.2% agarose gel.Using this method,we demonstrate a high-resolution separation of 0.5,1,2,5,and 10 kbp DNA fragments within 2 min.During the separation,DNA fragments are also purified from other ionic species.Preparative fractionation of sub-10-kbp DNA molecules plays an important role in second-generation sequencing.The presented device performs rapid high-resolution fractionation and it can be reliably manufactured with simple microfabrication procedures.展开更多
To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt b...To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt by physical property index,microscopic morphology,rheological testing,and infrared spectroscopy on multiple scales.The results show that the best preparation process for TB-modified asphalt is stirring at 260℃ for 4 h at 400 rpm,which significantly reduces the modification time of the asphalt.From a physical property viewpoint,the TB composite-modified asphalt sample with 5% styrene-butadiene-styrene(SBS)+1% aromatics+0.1% sulfur exhibits high-comprehensive,high-and low-temperature properties.More-over,its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle,which further enhances the performance of the asphalt and results in an excellent performance formulation.In addition,the sample with 5%SBS content has a higher G*value and smaller δ value than that with 3%SBS content,indicating that its high-temperature resistance is improved.The effect of adding 3%SBS content on the viscoelastic ratio is,to some extent,less than that caused by 20% rubber powder.展开更多
Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive n...Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive nature of titanium,metallic titanium production involves extensive procedures and high costs.Considering its advantages and limitations,the European Union has classified titanium metal as a critical raw material(CRM)of low category.The Kroll process is predominantly used to produce titanium;however,molten salt electrolysis(MSE)is currently being explored for producing metallic titanium at a low cost.Since 2000,electrolytic titanium production has undergone a wave of technological advancements.However,because of the intermediate and disproportionation reactions in the electrolytic titanium production process,the process efficiency and titanium purity according to industrial standards could not be achieved.Consequently,metallic titanium production has gradually diversified into employing technologies such as thermal reduction,MSE,and titanium alloy preparation.This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades,highlighting the challenges faced by the existing methods and proposing potential solutions.It offers useful insights into the development of low-cost titanium preparation technologies.展开更多
驾驶舱互联应用是指其通过技术手段,实现航班驾驶舱内部设备之间、设备数据与网络之间相互连通的应用。为普及驾驶舱互联应用在国内航班的运用,在地面搭建一个基于半实物仿真技术的平台是开展驾驶舱互联应用可行性验证的高效低成本方式...驾驶舱互联应用是指其通过技术手段,实现航班驾驶舱内部设备之间、设备数据与网络之间相互连通的应用。为普及驾驶舱互联应用在国内航班的运用,在地面搭建一个基于半实物仿真技术的平台是开展驾驶舱互联应用可行性验证的高效低成本方式。平台由仿真计算机、航空数据总线板卡和航电设备模块三部分组成,仿真计算机通过模拟飞行软件Prepar3D生成数据源,板卡将数据源转为ARINC 429等总线信号并驱动航电设备模块,航电设备模块由真实航电设备构成,可以仿真驾驶舱互联应用的过程。经测试,平台实现了在地面上对无线快速存取记录器参数网络传输、ACARS over IP等驾驶舱互联应用的仿真验证,提高了仿真的置信性。展开更多
The term“gut microbiota”primarily refers to the ecological community of various microorganisms in the gut,which constitutes the largest microbial community in the human body.Although adequate bowel preparation can i...The term“gut microbiota”primarily refers to the ecological community of various microorganisms in the gut,which constitutes the largest microbial community in the human body.Although adequate bowel preparation can improve the results of colonoscopy,it may interfere with the gut microbiota.Bowel preparation for colonoscopy can lead to transient changes in the gut microbiota,potentially affecting an individual’s health,especially in vulnerable populations,such as patients with inflammatory bowel disease.However,measures such as oral pro-biotics may ameliorate these adverse effects.We focused on the bowel prepa-ration-induced changes in the gut microbiota and host health status,hypothesized the factors influencing these changes,and attempted to identify measures that may reduce dysbiosis,thereby providing more information for individualized bowel preparation for colonoscopy in the future.展开更多
To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy(Cantor alloys,HEA)caused by the violent atomic interdiffusion,the higher configuration entropy on Cantor alloys surface was desi...To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy(Cantor alloys,HEA)caused by the violent atomic interdiffusion,the higher configuration entropy on Cantor alloys surface was designed and realized via eutectic high-entropy(EHEA)transformation.Meanwhile,to effectively alleviate the residual stress caused by the notable difference in the thermal expansion coefficient(CTE)between Cantor alloys and Zr-3 alloys,a cladding layer was applied to the HEA surface using laser cladding technology of Nb,followed by brazing to Zr-3 alloys with Zr63.2Cu filler.The cladding layer’s microstructure comprised Nbss and FCC+(Co,Ni)_(2) Nb eutectic structure,resulting from an in-situ reaction between Cantor alloys and Nb.The Nbss and FCC demonstrated good plasticity,and the(Co,Ni)_(2) Nb Laves phase provided increased strength,endowing both good plastic deformation ability and strength of the cladding layer.Notably,the existence of EHEA in the laser cladding layer made the Cantor alloy entropy from 1.61 R to 1.77 R,greatly enhancing its thermal stability and suppressing the grave grain boundary infiltration.Joints produced via laser cladding with Nb-assisted brazing exhibited a complex microstructure(HEA/Nbss+FCC+(Co,Ni)_(2)Nb/(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/(Zr,Nb)_(2)(Cu,Ni,Co,Fe)+(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/Zr-3) and a significantly improved shear strength of 242.8 MPa at 1010℃ for 10 min,42.4%higher than that of directly brazed joints.This improvement was attributed to reduced grain boundary infiltration,alleviated residual stress due to CTE disparity,and eliminated micro-cracks in the brazing seam.This study presents an effective solution for reducing residual stresses and achieving reliable bonding between Cantor alloys and Zr-3 alloys,with potential applications in brazing CoCrFeNi-based HEA and Zr-3 due to the beneficial eutectic reaction between CoCrFeNi and Nb.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42107284 and 22078177)the Postdoctoral Fellowship Program of CPSF(No.GZB20240410)。
文摘Decabromodiphenyl ethane(DBDPE)is widely used as an additive flame retardant and has led to global pollution.Its has a large molecular mass and is prone to debromination and degradation under photothermal conditions,resulting in smaller homologous compounds.Due to the lack of standard substances for debromination products,the in-depth study of DBDPE environmental geochemical behavior through debromination conversion has been hindered.Therefore,based on DBDPE photodegradation experiment,this study first analyzed and identified the brominated products of DBDPE using high-performance liquid chromatography-atmospheric pressure photoionization-time of flight mass spectrometry(HPLC-APPI-TOF/MS).Four debromination products-nonabromodiphenyl ethane(nonaBDPE),octabromodiphenyl ethane(octa-BDPE),heptabromodiphenyl ethane(hepta-BDPE)and hexabromodiphenyl ethane(hexa-BDPE)are identified based on the characteristic ion peak of[M-Br+O]^(-) in negative ion mode.Subsequently,using methanol as the mobile phase,four debromination products of DBDPE were separated and purified with a semi-preparative high-performance liquid chromatography(SP-HPLC)system equipped with an Agilent Zorbax Eclipse PAH column(4.6 mm×250 mm,5μm).The first-time acquisition of hexa-BDPE(60.00μg),octa-BDPE(19.40μg),hepta-BDPE(31.20μg)and octa-BDPE(isomer,45.20μg)with purity exceeding 90%has been achieved.Among them,the purity of one hepta-BDPE monomer is as high as 98.91%.This study indicates that based on photodegradation experiments,the combination of HPLC-APPI-TOF/MS and SP-HPLC techniques can rapidly identify and prepare DBDPE debrominated products.This approach meets the requirements for preliminary research on the pollution characteristics of DBDPE debrominated compounds and offers a feasible solution for the preparation of standard reference materials for emerging pollutants.
基金National Science Fund for Excellent Young Scholars(Grant No.81222051)National Key Technology R&D Program"New Drug Innovation"of China(Grant No.2012ZX09103201-036,2012ZX09301002-002-002 and 2012ZX09304-005)
文摘The aim of this study was to rapidly isolate the major effective flavanoids from the extract of safflower（Carthamus tinctorius） using ODS medium pressure liquid chromatography（MPLC） and semi-preparative HPLC, guided by a developed fingerprint. Twelve compounds were isolated and their structures were elucidated as kaempferol 3-O-β-D-rutinoside（1）, kaempferol 3-O-β-D-glucoside（2）, rutin（3）, quercetin 3-O-β-D-glucoside（4）, 6-hydroxykaempferol 3,6,7-tri-O-β-D-glucoside（5）, 6-hydroxykaempferol 3-O-β-D-glucoside（6）, 6-hydroxykaempferol 6,7-di-O-β-D-glucoside（7）, 6-hydroxykaempferol 3-O-β-Drutinoside（8）, 6-hydroxykaempferol 3,6-di-O-β-D-glucosyl 7-O-β-D-glucuronide（9）, isosafflomin C（10）, safflomin C（11） and hydroxysafflor yellow A（12） by spectroscopic analysis and comparing with the literature. Our results demonstrated that preparative pressurized liquid chromatography combined with HPLC fingerprint guide is an efficient tool to isolate the target compounds quickly.
基金supported by the National Natural Science Foundation of China
文摘It has been found that samples of sodium aluminate solutions with the same composition but different preparative history may have difTerent structure and physico-chemical properties.The structure of sodium-bearing aluminate solutions change very slowly during the storage after preparation.Sodium aluminate solutions contain several ammunium-bearing anisons such as Al(OH)^(-)_(4),Al(OH)^(3-)_(6)and[(HO)_(3)Al-O-Al(OH)_(3)]^(2-),etc.These anions can convert to each other but the reactions are very slow owing to the formation or breakage of covalent Al-O bond.Hence the ratio between these anions approaches equilibrium very slowly after the preparation,and the structure or properties of these solution samples before equilibrium is reached depend on their preparative histosive.
文摘1.IntroductionSodium aluminate solutions are veryimportant intermediate products in alumin-ium metallurgy.The physico-chemicalproperties of sodium aluminate solutions areconcerned by metallurgists and engineersdealing with alumina production[1].Thedata of viscosity,electroconductivity,UV
基金Supported by the Natural Science Foundation of Tianjin(No.993606911).
文摘In this paper a simple preparative method for isolation and purification of ginkgolides A and B was developed,As starting material,a commercially available standardized ginkgo extract (EGb761,containing 24% flavonoid and 6% terpene trilactones) was used,After a pretreatment step,optimized by the uniform design method ,the concentrated intermediate extract with high content of GA and gb(+90%) was separated into the individual terpenes by preparative liquid chromatography eluted with petroleum ether-ethylacetate,Analysis of products was carried out by means of HPLC-ELSD(evaporative light -scattering detector),The results show that ginkgolides A and B are obtained in higher yield and better purity.
基金Supported by the Science and Technology Plan of Liaoning Province, China(No.2006226002)the Project of the Doctor Fund of Hebei University of Science and Technology, China(No.005121)
文摘An efficient preparative method was successfully developed for isolation and purification of unstable components from medicinal plant extracts, using a combined method of preparative high performance liquid chro-matography(HPLC) and solid-phase extraction(SPE). The aim of this study was to obtain an effective method with high preparative efficiency and importantly to avoid the transformation of unstable compounds. The preparative HPLC system was based on an LC/MS controlled four-channel autopurification system. The SPE method was performed with a C18 packing material to trap the target compounds and to remove the acidic additive derived from the mobile phase. Using this method, the unstable iridoid glucosides(IGs) as model compounds were successfully isolated and purified from the extract of Hedyotis diffusa Willd. Six IGs(including one new minor IG) and one nucleotide compound were simultaneously obtained, each with a purity of 91% as determined by HPLC. The structures of the isolated compounds were identified by UPLC/Q-TOF MS, UV, 1D and/or 2D NMR. It was demonstrated that the combination of preparative HPLC with SPE is a versatile tool for preparative purification of unstable compounds from complex natural products.
基金supported by Guangdong Natural Science Foundation(S2013030013338)the Ph D.Programs Foundation of Ministry of Education of China(20114404130002)Guangdong Planed Program in Science and Technology(cgzhzd0808,2013B051000072,2012A020100002)
文摘Gatifloxacin （GFX） is a kind of chiral fluoroquinolones compound due to the methyl group at the C-3 position of the piperazine ring[1]. Although the enantiomers of GFX show similar levels of antimicrobial activity and pharmacokinetics[2], the other biological activities （i.e., toxicity or enantioselective recognition to various receptors in vivo） of GFX enantiomers have not yet been studied. With this in mind, we developed a rapid and cost-effective high performance liquid chromatographic （HPLC） separation procedure for GFX enantiomers with a pre-column esterification strategy.
文摘A liquid phase chemical bath deposition(LPCBD)method for deposition of PbS thin films is presented.The growth kinetics and reaction mechanism have been discussed.For the deposition,triethanolamine complex of lead acetate was allowed to react with aqueous thiourea solution.Glass micro-slides were used as the substrates.The deposition of PbS films was carried out under different growth parameters such as temperature,time,and reaction pH.The growth rate,under different conditions,was measured in terms of a terminal layer thickness and the possible reaction kinetics and mechanism is discussed.The optimum values of the parameters to produce good quality films are 60 min,80℃and 10.5±0.1.An EDS analysis showed that the film stoichiometry is dependent on the reaction pH and the films tend to be almost stoichiometric in high alkaline environment(>10.5).The PbS deposits appeared smooth,tightly adherent,uniform and reflecting with blackish-grey colour.The XRD studies showed crystalline cubic type of structure with preferred orientation along(200)plane.The calculated d-values,intensities of reflections and lattice parameter have excellent match with that of the JCPD data.The crystallite size is found to be few tens of nanometer.The surface morphology revealed by SEM showed that the crystallites are randomly oriented and are of different shapes and sizes.Majority of the crystallites appeared smaller and spherical in shape whereas,growth of some elongated irregular crystallites;bit larger in size and differing in shapes,have also been favoured.
基金Project supported by the National Natural Science Foundation of China (Nos. 40101017 and 40071048) the Senior Visitor Foundation of Chinese Educational Ministry.
文摘Birnessite occurs in a wide variety of natural environments, and plays animportant role in soil chemistry. A modified Staehli procedure was used to synthesize sodiumbirnessite in an alkali medium by O_2 oxidation. The effects of preparative parameters on thesynthesis of birnessite, such as pretreatment on solutions with N2, reaction temperature, O_2 flowrate, fluxion velocity of the reaction suspension, and dehydration conditions were investigated. Thefluxion velocity of the reactive suspension and O_2 flow rate significantly influenced thesynthesis of birnessite. Vigorous stirring raised the fluxion velocity of the reaction suspensionand easily allowed synthesis of pure crystalline birnessite. However pretreatment of the reactingsolutions with N_2 and the reaction temperature had little effect on the synthesis. Diffusion of O_2was the controlling step during the course of oxidation. The optimum synthetic conditions for purebirnessite were: a NaOH to Mn molar ratio of 13.7, an O_2 flow rate of 2 L min^(-1), and oxidationfor 5 hours with vigorous stirring at normal temperatures. The chemical composition of thesynthesized pure birnessite was Na_(0.25)MnO_(2.07)·0.66H_2O.
文摘Monodispersed potymeric microparticles were prepared by seed-poly- merization.High performance packings were obtained for anion chromatography by coating the surface-sutfonated partictes with quarternized latexes.
文摘Although mechanism of symbiosis between arbuscular mycorrhizal fungi (AMF) and host plants has been investigated by genetic analysis, very little knowledge has been obtained because genome analysis of AMF is not perfect yet. Thus, we tried to develop mass purification of proteins using preparative chromatography in order to accelerate roteomic analysis of proteins related to mycorrhizal symbiosis, such as 24 and 53 kDa proteins. In particular, our data showed that 53 kDa proteins would be restrictively expressed when mycorrhizal fungi and host plants were stressed. However, 24 kDa proteins, which appear to be a usable indicator for the existence of various my-corrhizal fungi, were habitually detected in not only AMF but also other mycorrhizal fungi such as ectomycorrhizal fungi (EF). Moreover, we discovered new preparative chromatographical techniques for isolation and mass purification of those proteins. We are convinced that this chromato-graphical technique will greatly contribute to proteomic approach of mycorrhizal symbiosis.
文摘This paper carried out a comparative analysis of different types of electrophoretic systems which were used for the analysis of casein complex from cow milk (polyacrylamide gel electrophoresis: for the neutral and acidic native conditions, in gradient variant, the presence of sodium dodecyl sulphate or with including urea). Taking into attention the separation efficiency, complexity of electrophoretic system, the impact of system components, we have selected the anode system of the homogeneous gel in the presence of urea as the basis for the preparation of casein fractions. It also changed the composition and the structure of the electrophoretic apparatus. The changes allow purification of casein fractions up to several grams during one stage of treatment (for 5 hours). The purified casein fractions were tested for the homogeneity and have been recommended for using in the biomedical researches, including the processes of the formation of the bioactive peptides.
文摘The renaturation and purification of recombinant human proinsulin (rh-proinsulin) expressed in E. coli with the unit of simultaneous renaturation and purification of protein (USRPP) in semi-preparative scale was studied. The result shows that rh-proinsulin extracted with 8.0 mol/L urea can be renatured and purified simultaneously in 45 minutes with the USRPP (1050 mm ID). The purity of rh-proinsulin was found to be more than 90% and the mass recovery to be more than 80%. The renaturation effect of rh-proinsulin with the USRPP was tested by enzyme cleavage for obtaining insulin. In addition, the result was further confirmed with RPLC, SDS-PAGE electrophoresis, and MALDI-TOF, respectively.
基金supported by the National Science and Technology Major Project for Major Drug Development(No.2013ZX09508104)the Traditional Chinese Medicine Industry Research Special Project(No.201307002)the National Science&Technology Major Project Key New Drug Creation and Manufacturing program(No.2011ZX09307002-03)of the People's Republic of China
文摘A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex Havil(UR)were chosen to show the advantage of this method.The sample enrichment and separation were
文摘A new approach is presented for preparative,continuous flow fractionation of sub-10-kbp DNA fragments,which exploits the variation in the field-dependent mobility of the DNA molecules based on their length.Orthogonally pulsed electric fields of significantly different magnitudes are applied to a microchip filled with a sieving matrix of 1.2% agarose gel.Using this method,we demonstrate a high-resolution separation of 0.5,1,2,5,and 10 kbp DNA fragments within 2 min.During the separation,DNA fragments are also purified from other ionic species.Preparative fractionation of sub-10-kbp DNA molecules plays an important role in second-generation sequencing.The presented device performs rapid high-resolution fractionation and it can be reliably manufactured with simple microfabrication procedures.
基金Funded by the National Natural Science Foundation of China(No.52278446)。
文摘To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt by physical property index,microscopic morphology,rheological testing,and infrared spectroscopy on multiple scales.The results show that the best preparation process for TB-modified asphalt is stirring at 260℃ for 4 h at 400 rpm,which significantly reduces the modification time of the asphalt.From a physical property viewpoint,the TB composite-modified asphalt sample with 5% styrene-butadiene-styrene(SBS)+1% aromatics+0.1% sulfur exhibits high-comprehensive,high-and low-temperature properties.More-over,its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle,which further enhances the performance of the asphalt and results in an excellent performance formulation.In addition,the sample with 5%SBS content has a higher G*value and smaller δ value than that with 3%SBS content,indicating that its high-temperature resistance is improved.The effect of adding 3%SBS content on the viscoelastic ratio is,to some extent,less than that caused by 20% rubber powder.
基金financial support from the Yunnan Province Key Industries Science and Technology Special Project for Colleges and UniversitiesChina(No.FWCY-QYCT2024006)+6 种基金National Natural Science Foundation of China(Nos.52104351 and 52364051)Science and Technology Major Project of Yunnan Province,China(No.202202AG050007)the Yunnan Fundamental Research ProjectsChina(No.202401AT070314)the Key Technology Research and Development Program of Shandong Province,China(No.2023CXGC010903)Central Guidance Local Scientific and Technological Development Funds,China(No.202407AB110022)Yunnan Province Xingdian Talent Support Plan Project,China。
文摘Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive nature of titanium,metallic titanium production involves extensive procedures and high costs.Considering its advantages and limitations,the European Union has classified titanium metal as a critical raw material(CRM)of low category.The Kroll process is predominantly used to produce titanium;however,molten salt electrolysis(MSE)is currently being explored for producing metallic titanium at a low cost.Since 2000,electrolytic titanium production has undergone a wave of technological advancements.However,because of the intermediate and disproportionation reactions in the electrolytic titanium production process,the process efficiency and titanium purity according to industrial standards could not be achieved.Consequently,metallic titanium production has gradually diversified into employing technologies such as thermal reduction,MSE,and titanium alloy preparation.This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades,highlighting the challenges faced by the existing methods and proposing potential solutions.It offers useful insights into the development of low-cost titanium preparation technologies.
文摘驾驶舱互联应用是指其通过技术手段,实现航班驾驶舱内部设备之间、设备数据与网络之间相互连通的应用。为普及驾驶舱互联应用在国内航班的运用,在地面搭建一个基于半实物仿真技术的平台是开展驾驶舱互联应用可行性验证的高效低成本方式。平台由仿真计算机、航空数据总线板卡和航电设备模块三部分组成,仿真计算机通过模拟飞行软件Prepar3D生成数据源,板卡将数据源转为ARINC 429等总线信号并驱动航电设备模块,航电设备模块由真实航电设备构成,可以仿真驾驶舱互联应用的过程。经测试,平台实现了在地面上对无线快速存取记录器参数网络传输、ACARS over IP等驾驶舱互联应用的仿真验证,提高了仿真的置信性。
文摘The term“gut microbiota”primarily refers to the ecological community of various microorganisms in the gut,which constitutes the largest microbial community in the human body.Although adequate bowel preparation can improve the results of colonoscopy,it may interfere with the gut microbiota.Bowel preparation for colonoscopy can lead to transient changes in the gut microbiota,potentially affecting an individual’s health,especially in vulnerable populations,such as patients with inflammatory bowel disease.However,measures such as oral pro-biotics may ameliorate these adverse effects.We focused on the bowel prepa-ration-induced changes in the gut microbiota and host health status,hypothesized the factors influencing these changes,and attempted to identify measures that may reduce dysbiosis,thereby providing more information for individualized bowel preparation for colonoscopy in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.52275321 and 52205348)the Shandong Natural Science Foundation(Grant No.ZR2023JQ021)+3 种基金the Taishan Scholars Foundation of Shandong Province(No.tsqn 201812128)the Innovation Scientists and Technicians Troop Projects of Henan Province(No.204200510031)the Heilongjiang Touyan Innovation Team Program(No.HITTY-20190013)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(Nos.NRF-2021R1A2C3006662 and NRF-2022R1A5A1030054).
文摘To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy(Cantor alloys,HEA)caused by the violent atomic interdiffusion,the higher configuration entropy on Cantor alloys surface was designed and realized via eutectic high-entropy(EHEA)transformation.Meanwhile,to effectively alleviate the residual stress caused by the notable difference in the thermal expansion coefficient(CTE)between Cantor alloys and Zr-3 alloys,a cladding layer was applied to the HEA surface using laser cladding technology of Nb,followed by brazing to Zr-3 alloys with Zr63.2Cu filler.The cladding layer’s microstructure comprised Nbss and FCC+(Co,Ni)_(2) Nb eutectic structure,resulting from an in-situ reaction between Cantor alloys and Nb.The Nbss and FCC demonstrated good plasticity,and the(Co,Ni)_(2) Nb Laves phase provided increased strength,endowing both good plastic deformation ability and strength of the cladding layer.Notably,the existence of EHEA in the laser cladding layer made the Cantor alloy entropy from 1.61 R to 1.77 R,greatly enhancing its thermal stability and suppressing the grave grain boundary infiltration.Joints produced via laser cladding with Nb-assisted brazing exhibited a complex microstructure(HEA/Nbss+FCC+(Co,Ni)_(2)Nb/(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/(Zr,Nb)_(2)(Cu,Ni,Co,Fe)+(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/Zr-3) and a significantly improved shear strength of 242.8 MPa at 1010℃ for 10 min,42.4%higher than that of directly brazed joints.This improvement was attributed to reduced grain boundary infiltration,alleviated residual stress due to CTE disparity,and eliminated micro-cracks in the brazing seam.This study presents an effective solution for reducing residual stresses and achieving reliable bonding between Cantor alloys and Zr-3 alloys,with potential applications in brazing CoCrFeNi-based HEA and Zr-3 due to the beneficial eutectic reaction between CoCrFeNi and Nb.
