Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous ...Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous reversed phase(NARP) HPLC on C_(18) column with UV detection at 215nm.展开更多
With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chro...With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chromatography (RPLC) was investigated by on line UV spectrometry and identified with nuclear magnetic resonance (NMR) spectrometry and mass spectrometry. The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis (FA). When the insulin concentration was limited to a certain range, the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten. The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components. The displaced methanol was quantitatively determined by NMR and on line UV spectrometries. TFA with high UV absorbance can not be used as an ion pairing agent for the investigation of the FP in RPLC, but it can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC. A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC. From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC, while solute can penetrate into it in FA of RPLC. The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.展开更多
With four kinds of mobile phases, methanol water, ethanol water, 2 propanol and acetonitrile water (all containing 0 1% triflu roacetic acid), the displacement between solute and solvent in RPLC was proved to be...With four kinds of mobile phases, methanol water, ethanol water, 2 propanol and acetonitrile water (all containing 0 1% triflu roacetic acid), the displacement between solute and solvent in RPLC was proved to be universal in frontal analysis (FA). Based on the measured Z value in usual RPLC to be a constant and the quantitative determination of methanol increment in mobile phase in FA, the stoichiometric displacement (SD) between insulin and methanol was directly proved by the experiment. The SD was also proved to occur only on about the one fourth of the maximum amount of adsorbed methanol in the bonded phase layer (BPL) without any dynamic problem of mass transfer, while in FA, the SD firstly occurs on the surface of the BPL and then gradually sinks into the deeper sites companied with a dynamic problem. Although the displaced solvent by the same solute is less in the former case, the SD is independent of how deep of the solute enters the BPL. In addition, the adsorbed amount of solute on an adsorbent not only depends on the numbers of the adsorbed layer on the adsorbent surface, but also on the extent of the complete removal of the displaceable solvent in the BPL. The physical fundamental of the SD and the methodology for investigation were also discussed.展开更多
With frontal analysis (FA), the dependence of adsorption isotherms of insulin on the composition of mobile phase in reversed phase liquid chromatography (RPLC) has been investigated. This is also a good example to em...With frontal analysis (FA), the dependence of adsorption isotherms of insulin on the composition of mobile phase in reversed phase liquid chromatography (RPLC) has been investigated. This is also a good example to employ the stoichiometric displacement theory (SDT) for investigating solute adsorption in physical chemistry. Six kinds of mobile phase in RPLC were employed to study the effects on the elution curves and adsorption isotherms of insulin. The key points of this paper are: (1) The stability of insulin due to delay time after preparing, the organic solvent concentration, the kind and the concentration of ion pairing agent in mobile phase were found to affect both elution curve and adsorption isotherm very seriously. (2) To obtain a valid and comparable result, the composition of the mobile phase employed in FA must be as same as possible to that in usual RPLC of either analytical scale or preparative purpose. (3) Langmuir Equation and the SDT were employed to imitate these obtained adsorption isotherms. The expression for solute adsorption from solution of the SDT was found to have a better elucidation to the insulin adsorption from mobile phase in RPLC.展开更多
Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.Ho...Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.However,the irreversible phase transition often brings rapid capacity decay,which seriously hinders the practical application in large-scale energy storage.Herein,we design a nickel-doped Na_(0.70)Fe_(0.10)Cu_(0.20)Ni_(0.05)Mn_(0.65)O_(2)(NFCNM-0.05)cathode material of SIBs with activated anionic redox reaction,and then inhibit the harmful phase transition.The ex-situ X-ray diffraction patterns demonstrate the NFCNM-0.05 always keeps the P2 phase during the sodiation/desodiation process,indicating a high structure stability.The ex-situ X-ray photoelectron spectroscopy implies the redox reactions between O2-and O-occur in the charging process,which offers extra specific capacity.Thus,the NFCNM-0.05 electrode delivers a high initial discharge capacity of 148 mA h g-1and remains a prominent cycling stability with an excellent capacity retention of 95.9%after 200 cycles at 1 C.In addition,the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique show the NFCNM-0.05 electrode possesses fast ion diffusion ability,which is beneficial for the enhancement of rate performance.Even at 10 C,the NFCNM-0.05 can offer a reversible discharge capacity of 81 mA h g-1.DFT calculation demonstrates the doping of appropriate amount of Ni ions is benefit for the enhancement of the electrochemical performance of the layer oxides.This work provides an effective strategy to enhance the electrochemical performance of Fe-Mn based cathode materials of SIBs.展开更多
WHO strategy on traditional medicine is based on security and quality of phytomedicine. Commonly adulterated affecting mostly metabolic and sexual dysfunction drugs. Control quality of those phytomedicines requires de...WHO strategy on traditional medicine is based on security and quality of phytomedicine. Commonly adulterated affecting mostly metabolic and sexual dysfunction drugs. Control quality of those phytomedicines requires development of strategy and techniques applicable to them. Among the techniques, Reverse Phase Liquid Chromatography is the most used and has been developed in these studies to assess a protocol to characterize Gardenia aqualla leaves extract. The method consists in determining chromatographic conditions using organic and pH gradient models based on water and acetonitrile combined with pH modifiers made up of formic acid (AF) and ammonium hydroxide (NH<sub>3</sub>). Results show that extracts contain mainly acidic compounds quickly eluted by NH<sub>3</sub> and more retained by AF. Optimal pH range for separation is 3 - 7 corresponding to 1.59 mM of NH<sub>3</sub> and 6.55 mM of AF. In these conditions, elution of many polar compounds could be effective using a C18 based-deactivated column in a short period of time.展开更多
A novel gradient pressurized capillary electrochromatography (pCEC) instrument was developed to separate peptides. Two gradient elution modes, hydrophobic and hydrophilic interaction mode in pCEC, were performed on t...A novel gradient pressurized capillary electrochromatography (pCEC) instrument was developed to separate peptides. Two gradient elution modes, hydrophobic and hydrophilic interaction mode in pCEC, were performed on this instrument. Baseline separation of six peptides was obtained on two gradient modes with C18 column and strong cationic exchange column respectively. The effects of mixer volume and total flow rate of pumps on resolution were also discussed.展开更多
To identify acute renal allograft rejection biomarkers in human serum, two-dimensional differential in-gel electrophoresis (2-D DIGE) and reversed phase high-performance liquid chromatography (RP-HPLC) followed by...To identify acute renal allograft rejection biomarkers in human serum, two-dimensional differential in-gel electrophoresis (2-D DIGE) and reversed phase high-performance liquid chromatography (RP-HPLC) followed by electrospray ionization mass spectrometry (ESI-MS) were used. Serum samples from renal allograft patients and normal volunteers were divided into three groups: acute rejec- tion (AR), stable renal function (SRF) and normal volunteer (N). Serum samples were firstly processed using Multiple Affinity Removal Column to selectively remove the highest abundance proteins. Differentially expressed proteins were analyzed using 2-D DIGE. These differential protein spots were excised, digested by trypsin, and identified by RP-HPLC-ESI/MS. Twenty-two differentially expressed proteins were identified in serum from AR group. These proteins included complement C9 precursor, apolipoprotein A-IV precursor, vitamin D-binding protein precursor, beta-2-glycoprotein 1 precursor, etc. Vitamin D-binding protein, one of these proteins, was confirmed by ELISA in the independent set of serum samples. In conclusion, the differentially expressed proteins as serum biomarker candidates may provide the basis of acute rejection noninvasive diagnosis. Confirmed vitamin D-binding protein may be one of serum biomarkers of acute rejection. Furthermore, it may provide great insights into understanding the mechanisms and potential treatment strategy of acute rejection.展开更多
Rapid and sensitive reversed phase high performance liquid chromatography (RP-HPLC) and ultra performance liquid chromatography (RP-UPLC) method with UV detection has been developed and validated for quantification of...Rapid and sensitive reversed phase high performance liquid chromatography (RP-HPLC) and ultra performance liquid chromatography (RP-UPLC) method with UV detection has been developed and validated for quantification of parathyroid hormone (PTH) in presence of meta-cresol as a stabilizer in a pharmaceutical formulation.Chromatography was performed with mobile phase containing 0.1% Trifluoroacetic acid (TFA) in MilliQ water and 0.1% TFA in acetonitrile with gradient program and flow rate at 0.3 mL/min for HPLC and 0.4 mL/min for UPLC.Quantification was accomplished with internal reference standard (qualified against innovator product and National Institute for Biological Standards and Control (NIBSC) standard).The methods were validated for linearity (correlation coefficient 0.99),range,accuracy,precision and robustness.Robustness was confirmed by considering three factors;mobile phase composition,column temperature and flow rate/age of mobile phase.Intermediate precision was confirmed on different equipments,different columns and on different days.The relative standard deviation (RSD) (<2% for RP-HPLC and <1% for UPLC,n=30) indicated a good precision.Retention time was found about 17 min and 2 min by HPLC and UPLC methods,respectively.Both methods are simple,highly sensitive,precise and accurate and have the potential of being useful for routine quality control.展开更多
Sixteen indole derivatives have been computed at B3LYP/6-31 IG^** level using density functional theory (DFF). Based on linear solvation energy theory, the structural parameters were employed to present correlatio...Sixteen indole derivatives have been computed at B3LYP/6-31 IG^** level using density functional theory (DFF). Based on linear solvation energy theory, the structural parameters were employed to present correlation between the parameters of chromatograph capacity factor (CCF) and molecular structural parameters. As a result, the correlation equation of the reversed phased high performance liquid chromatograph capacity factor to the intercept lgk'w and slope S of CCF were obtained, from which the correlation coefficients of lgk'w to the structural parameters are r^2 = 0.9596 and q^2 = 0.9262. While the correlation coefficients of the parameter S r^2 q^2 with structures are = 0.9750 and = 0.9252. Moreover, the effect of water as solvent on the present two models was also considered using SCRF method, and the result shows that the predicting capacity of correlation equation of lgkw' increases, while that of the model for S decreases slightly. Both two correlation equations achieved in this work are more advantageous than those using theoretical descriptors from molecular connectivity indices.展开更多
A convenient derivatization method of amino acids with 1-fluoro-2,4-dinitrobezene as reaction reagent and a separation system were described. The derivative amino acids were separated on a specific chemically bonded p...A convenient derivatization method of amino acids with 1-fluoro-2,4-dinitrobezene as reaction reagent and a separation system were described. The derivative amino acids were separated on a specific chemically bonded phase column with a simple linear gradient elution consisting of aqueous buffer and methanol. The eluate was detected by common ultraviolet absorption detector at 360 nm. The detection limits of amino acids were as low as 10 picomole. This method has been successfully applied to assay amino acid injection liquor used in hospital. It has good reproducibility and precision. The procedures avoid the requirements of particular derivative equipment and analyzer employed in conventional amino acid analysis.展开更多
Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses a...Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.展开更多
Mechanism of FCC→HCP reverse phase transformation in face-centered cubic zirconium(FCC-Zr)along with a concomitant 70.5°rotation ofα-Zr matrix were investigated in zircaloy-4(Zr-4)cladding tube by using transmi...Mechanism of FCC→HCP reverse phase transformation in face-centered cubic zirconium(FCC-Zr)along with a concomitant 70.5°rotation ofα-Zr matrix were investigated in zircaloy-4(Zr-4)cladding tube by using transmission electron microscopy(TEM).Results showed that the interaction among a secondary phase particle(SPP)and three FCC-Zr grains resulted in the formation of cross stacking faults in SPP and exerted a drag force on minor axis of the adjacent FCC-Zr phase.Moreover,when the shear stress along[112]_(FCC-Zr)direction was large enough to initiate the emission of 1/6[112]Shockley partial dislocation on every other(111)_(FCC-Zr)close-packed plane,the stacking sequence would change from ABC ABCA to AB ABABA viz.(0001)planes of the daughter HCP phase.Thus,FCC→HCP reverse phase transformation in FCC-Zr was presented.展开更多
Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptoticall...Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptotically flat nor(A)dS.The calculated thermodynamic quantities,such as mass,temperature,and entropy,verify the validity of the first law of black hole thermodynamics.Moreover,we further investigate the critical behaviors of these black holes in the grand canonical and canonical ensembles and find a novel critical phenomenon never before observed,known as the"reverse"reentrant phase transition with a tricritical point.It implies that the system undergoes a novel"SBH-LBH-SBH"phase transition process and is the reverse of the"LBH-SBH-LBH"process observed in reentrant phase transitions.展开更多
Phase transition is common during (de)-intercalating layered sodium oxides, which directly affects the structural stability and electrochemical performance. However, the artificial control of phase transition to achie...Phase transition is common during (de)-intercalating layered sodium oxides, which directly affects the structural stability and electrochemical performance. However, the artificial control of phase transition to achieve advanced sodium-ion batteries is lacking, since the remarkably little is known about the influencing factor relative to the sliding process of transition-metal slabs upon sodium release and uptake of layered oxides. Herein, we for the first time demonstrate the manipulation of oxygen vacancy concentrations in multinary metallic oxides has a significant impact on the reversibility of phase transition, thereby determining the sodium storage performance of cathode materials. Results show that abundant oxygen vacancies intrigue the return of the already slide transition-metal slabs between O_(3) and P_(3) phase transition, in contrast to the few oxygen vacancies and resulted irreversibility. Additionally, the abundant oxygen vacancies enhance the electronic and ionic conductivity of the Na0.9Ni0.3Co0.15Mn0.05Ti0.5O2 electrode, delivering the high initial Coulombic efficiency of 97.1%, large reversible capacity of 112.7 mAh·g−1, superior rate capability upon 100 C and splendid cycling performance over 1,000 cycles. Our findings open up new horizons for artificially manipulating the structural evolution and electrochemical process of layered cathodes, and pave a way in designing advanced sodium-ion batteries.展开更多
For the isomers of amino benzoic acid, including o-, m-, p-amino benzoic acid, the beneficial effects of using the ionic liquid, l-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), as mobile phase additives...For the isomers of amino benzoic acid, including o-, m-, p-amino benzoic acid, the beneficial effects of using the ionic liquid, l-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), as mobile phase additives on retention behavior and separation were investigated. Chromatographic separation of the o-, m-, p-amino benzoic acid was performed on a reversed-phase C18 column by ultraviolet detection at 245 nm. The effects of several chromatographic parameters, concentrations and pH values of [BMIm][BF4] solutions, methanol concentration and length of alkyl chain on different ionic liquids, on the separation and determination of the isomers were evaluated. The optimized chromatographic conditions were established using an aqueous 0.5 mmol/L [BMIm][BF4] solution (pH 3.0)/methanol (40:60, v/v) as mobile phase without need of gradient eiution, with separation of three amino benzoic acids achieved within four min. The calibration curve showed good linearity over the tested range of 2 mg/L to 120 mg/L for the three isomers with a correlation coefficients of 0.9999. The recoveries of the three amino benzoic acids of spiked components were between 99.8% and 100%. The method has been successfully applied to the determination of p-amino benzoic acid in the pharmaceutical, Bromine Mitag Procaine Injection.展开更多
In this study we systematically analyzed the elution condition of tryptic peptides and the characteristics of identi?ed peptides in reverse phase liquid chromatogra- phy and electrospray tandem mass spectrometry (RPLC...In this study we systematically analyzed the elution condition of tryptic peptides and the characteristics of identi?ed peptides in reverse phase liquid chromatogra- phy and electrospray tandem mass spectrometry (RPLC-MS/MS) analysis. Fol- lowing protein digestion with trypsin, the peptide mixture was analyzed by on-line RPLC-MS/MS. Bovine serum albumin (BSA) was used to optimize acetonitrile (ACN) elution gradient for tryptic peptides, and Cytochrome C was used to retest the gradient and the sensitivity of LC-MS/MS. The characteristics of identi?ed peptides were also analyzed. In our experiments, the suitable ACN gradient is 5% to 30% for tryptic peptide elution and the sensitivity of LC-MS/MS is 50 fmol. Analysis of the tryptic peptides demonstrated that longer (more than 10 amino acids) and multi-charge state (+2, +3) peptides are likely to be identi?ed, and the hydropathicity of the peptides might not be related to whether it is more likely to be identi?ed or not. The number of identi?ed peptides for a protein might be used to estimate its loading amount under the same sample background. Moreover, in this study the identi?ed peptides present three types of redundancy, namely iden- ti?cation, charge, and sequence redundancy, which may repress low abundance protein identi?cation.展开更多
Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,whic...Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.展开更多
文摘Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous reversed phase(NARP) HPLC on C_(18) column with UV detection at 215nm.
文摘With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chromatography (RPLC) was investigated by on line UV spectrometry and identified with nuclear magnetic resonance (NMR) spectrometry and mass spectrometry. The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis (FA). When the insulin concentration was limited to a certain range, the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten. The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components. The displaced methanol was quantitatively determined by NMR and on line UV spectrometries. TFA with high UV absorbance can not be used as an ion pairing agent for the investigation of the FP in RPLC, but it can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC. A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC. From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC, while solute can penetrate into it in FA of RPLC. The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.
文摘With four kinds of mobile phases, methanol water, ethanol water, 2 propanol and acetonitrile water (all containing 0 1% triflu roacetic acid), the displacement between solute and solvent in RPLC was proved to be universal in frontal analysis (FA). Based on the measured Z value in usual RPLC to be a constant and the quantitative determination of methanol increment in mobile phase in FA, the stoichiometric displacement (SD) between insulin and methanol was directly proved by the experiment. The SD was also proved to occur only on about the one fourth of the maximum amount of adsorbed methanol in the bonded phase layer (BPL) without any dynamic problem of mass transfer, while in FA, the SD firstly occurs on the surface of the BPL and then gradually sinks into the deeper sites companied with a dynamic problem. Although the displaced solvent by the same solute is less in the former case, the SD is independent of how deep of the solute enters the BPL. In addition, the adsorbed amount of solute on an adsorbent not only depends on the numbers of the adsorbed layer on the adsorbent surface, but also on the extent of the complete removal of the displaceable solvent in the BPL. The physical fundamental of the SD and the methodology for investigation were also discussed.
文摘With frontal analysis (FA), the dependence of adsorption isotherms of insulin on the composition of mobile phase in reversed phase liquid chromatography (RPLC) has been investigated. This is also a good example to employ the stoichiometric displacement theory (SDT) for investigating solute adsorption in physical chemistry. Six kinds of mobile phase in RPLC were employed to study the effects on the elution curves and adsorption isotherms of insulin. The key points of this paper are: (1) The stability of insulin due to delay time after preparing, the organic solvent concentration, the kind and the concentration of ion pairing agent in mobile phase were found to affect both elution curve and adsorption isotherm very seriously. (2) To obtain a valid and comparable result, the composition of the mobile phase employed in FA must be as same as possible to that in usual RPLC of either analytical scale or preparative purpose. (3) Langmuir Equation and the SDT were employed to imitate these obtained adsorption isotherms. The expression for solute adsorption from solution of the SDT was found to have a better elucidation to the insulin adsorption from mobile phase in RPLC.
基金supported by the National Natural Science Foundation of China(U1960107)the Natural Science Foundation of Hebei Province(E2022501014)+3 种基金the “333”Talent Project of Hebei Province(A202005018)the Fundamental Research Funds for the Central Universities(N2123034)the Science and Technology Research Youth Fund Project of Higher Education Institutions of Hebei Province(QN2022196)the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.However,the irreversible phase transition often brings rapid capacity decay,which seriously hinders the practical application in large-scale energy storage.Herein,we design a nickel-doped Na_(0.70)Fe_(0.10)Cu_(0.20)Ni_(0.05)Mn_(0.65)O_(2)(NFCNM-0.05)cathode material of SIBs with activated anionic redox reaction,and then inhibit the harmful phase transition.The ex-situ X-ray diffraction patterns demonstrate the NFCNM-0.05 always keeps the P2 phase during the sodiation/desodiation process,indicating a high structure stability.The ex-situ X-ray photoelectron spectroscopy implies the redox reactions between O2-and O-occur in the charging process,which offers extra specific capacity.Thus,the NFCNM-0.05 electrode delivers a high initial discharge capacity of 148 mA h g-1and remains a prominent cycling stability with an excellent capacity retention of 95.9%after 200 cycles at 1 C.In addition,the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique show the NFCNM-0.05 electrode possesses fast ion diffusion ability,which is beneficial for the enhancement of rate performance.Even at 10 C,the NFCNM-0.05 can offer a reversible discharge capacity of 81 mA h g-1.DFT calculation demonstrates the doping of appropriate amount of Ni ions is benefit for the enhancement of the electrochemical performance of the layer oxides.This work provides an effective strategy to enhance the electrochemical performance of Fe-Mn based cathode materials of SIBs.
文摘WHO strategy on traditional medicine is based on security and quality of phytomedicine. Commonly adulterated affecting mostly metabolic and sexual dysfunction drugs. Control quality of those phytomedicines requires development of strategy and techniques applicable to them. Among the techniques, Reverse Phase Liquid Chromatography is the most used and has been developed in these studies to assess a protocol to characterize Gardenia aqualla leaves extract. The method consists in determining chromatographic conditions using organic and pH gradient models based on water and acetonitrile combined with pH modifiers made up of formic acid (AF) and ammonium hydroxide (NH<sub>3</sub>). Results show that extracts contain mainly acidic compounds quickly eluted by NH<sub>3</sub> and more retained by AF. Optimal pH range for separation is 3 - 7 corresponding to 1.59 mM of NH<sub>3</sub> and 6.55 mM of AF. In these conditions, elution of many polar compounds could be effective using a C18 based-deactivated column in a short period of time.
基金The study is supported by NNSFC,grant No.20175010.
文摘A novel gradient pressurized capillary electrochromatography (pCEC) instrument was developed to separate peptides. Two gradient elution modes, hydrophobic and hydrophilic interaction mode in pCEC, were performed on this instrument. Baseline separation of six peptides was obtained on two gradient modes with C18 column and strong cationic exchange column respectively. The effects of mixer volume and total flow rate of pumps on resolution were also discussed.
基金supported by a grant from National Basic Research 973 Program of China (No.2009CB522407)
文摘To identify acute renal allograft rejection biomarkers in human serum, two-dimensional differential in-gel electrophoresis (2-D DIGE) and reversed phase high-performance liquid chromatography (RP-HPLC) followed by electrospray ionization mass spectrometry (ESI-MS) were used. Serum samples from renal allograft patients and normal volunteers were divided into three groups: acute rejec- tion (AR), stable renal function (SRF) and normal volunteer (N). Serum samples were firstly processed using Multiple Affinity Removal Column to selectively remove the highest abundance proteins. Differentially expressed proteins were analyzed using 2-D DIGE. These differential protein spots were excised, digested by trypsin, and identified by RP-HPLC-ESI/MS. Twenty-two differentially expressed proteins were identified in serum from AR group. These proteins included complement C9 precursor, apolipoprotein A-IV precursor, vitamin D-binding protein precursor, beta-2-glycoprotein 1 precursor, etc. Vitamin D-binding protein, one of these proteins, was confirmed by ELISA in the independent set of serum samples. In conclusion, the differentially expressed proteins as serum biomarker candidates may provide the basis of acute rejection noninvasive diagnosis. Confirmed vitamin D-binding protein may be one of serum biomarkers of acute rejection. Furthermore, it may provide great insights into understanding the mechanisms and potential treatment strategy of acute rejection.
文摘Rapid and sensitive reversed phase high performance liquid chromatography (RP-HPLC) and ultra performance liquid chromatography (RP-UPLC) method with UV detection has been developed and validated for quantification of parathyroid hormone (PTH) in presence of meta-cresol as a stabilizer in a pharmaceutical formulation.Chromatography was performed with mobile phase containing 0.1% Trifluoroacetic acid (TFA) in MilliQ water and 0.1% TFA in acetonitrile with gradient program and flow rate at 0.3 mL/min for HPLC and 0.4 mL/min for UPLC.Quantification was accomplished with internal reference standard (qualified against innovator product and National Institute for Biological Standards and Control (NIBSC) standard).The methods were validated for linearity (correlation coefficient 0.99),range,accuracy,precision and robustness.Robustness was confirmed by considering three factors;mobile phase composition,column temperature and flow rate/age of mobile phase.Intermediate precision was confirmed on different equipments,different columns and on different days.The relative standard deviation (RSD) (<2% for RP-HPLC and <1% for UPLC,n=30) indicated a good precision.Retention time was found about 17 min and 2 min by HPLC and UPLC methods,respectively.Both methods are simple,highly sensitive,precise and accurate and have the potential of being useful for routine quality control.
基金This work was supported by the National Basic Research Program of China (2003CB415002) and the China Postdoctoral Science Foundation (No. 2003033486) and the Natural Science Research Fund of University in Jiangsu (04KJB150149)
文摘Sixteen indole derivatives have been computed at B3LYP/6-31 IG^** level using density functional theory (DFF). Based on linear solvation energy theory, the structural parameters were employed to present correlation between the parameters of chromatograph capacity factor (CCF) and molecular structural parameters. As a result, the correlation equation of the reversed phased high performance liquid chromatograph capacity factor to the intercept lgk'w and slope S of CCF were obtained, from which the correlation coefficients of lgk'w to the structural parameters are r^2 = 0.9596 and q^2 = 0.9262. While the correlation coefficients of the parameter S r^2 q^2 with structures are = 0.9750 and = 0.9252. Moreover, the effect of water as solvent on the present two models was also considered using SCRF method, and the result shows that the predicting capacity of correlation equation of lgkw' increases, while that of the model for S decreases slightly. Both two correlation equations achieved in this work are more advantageous than those using theoretical descriptors from molecular connectivity indices.
基金supported by the National Natural Science Foundation of China.
文摘A convenient derivatization method of amino acids with 1-fluoro-2,4-dinitrobezene as reaction reagent and a separation system were described. The derivative amino acids were separated on a specific chemically bonded phase column with a simple linear gradient elution consisting of aqueous buffer and methanol. The eluate was detected by common ultraviolet absorption detector at 360 nm. The detection limits of amino acids were as low as 10 picomole. This method has been successfully applied to assay amino acid injection liquor used in hospital. It has good reproducibility and precision. The procedures avoid the requirements of particular derivative equipment and analyzer employed in conventional amino acid analysis.
基金supported by the Natural Science Foundation of China(Grant No.51902246,12161141012,and 12174299)the China National Key R&D Program(Grant No.2021YFB3201800 and 2020YFC0122100)+5 种基金the Natural Science Fundamental Research Project of Shaanxi Province of China(No.2019JQ590)the Key R&D Program of Shaanxi Province of China(2020GY-271)the Fundamental Research Funds for the Central Universities(xzd012020059)the“111 Project”of China(B14040)the Natural Sciences&Engineering Research Council of Canada(NSERC,Discovery Grant No.RGPIN-2017-06915)Xijiang Innovation Team Introduction Program of Zhaoqing(Jiecheng).
文摘Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.
基金The authors appreciate Dr.Jinmin Liu and Dr.Xiaolan Wang for TEM measurements.
文摘Mechanism of FCC→HCP reverse phase transformation in face-centered cubic zirconium(FCC-Zr)along with a concomitant 70.5°rotation ofα-Zr matrix were investigated in zircaloy-4(Zr-4)cladding tube by using transmission electron microscopy(TEM).Results showed that the interaction among a secondary phase particle(SPP)and three FCC-Zr grains resulted in the formation of cross stacking faults in SPP and exerted a drag force on minor axis of the adjacent FCC-Zr phase.Moreover,when the shear stress along[112]_(FCC-Zr)direction was large enough to initiate the emission of 1/6[112]Shockley partial dislocation on every other(111)_(FCC-Zr)close-packed plane,the stacking sequence would change from ABC ABCA to AB ABABA viz.(0001)planes of the daughter HCP phase.Thus,FCC→HCP reverse phase transformation in FCC-Zr was presented.
基金Supported by the National Key Research and Development Program of China(2020YFC2201400)supported by the National Natural Science Foundation of China(12365009)the Natural Science Foundation of Jiangxi Province,China(20232BAB201039)。
文摘Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptotically flat nor(A)dS.The calculated thermodynamic quantities,such as mass,temperature,and entropy,verify the validity of the first law of black hole thermodynamics.Moreover,we further investigate the critical behaviors of these black holes in the grand canonical and canonical ensembles and find a novel critical phenomenon never before observed,known as the"reverse"reentrant phase transition with a tricritical point.It implies that the system undergoes a novel"SBH-LBH-SBH"phase transition process and is the reverse of the"LBH-SBH-LBH"process observed in reentrant phase transitions.
基金The financial is supported by the National Natural Science Foundation of China (Nos. 22075132, 51802149, and U1801251)the Fundamental Research Funds for the Central Universities, and Nanjing University Technology Innovation Fund Project. The authors are also grateful to the High Performance Computing Center (HPCC) of Nanjing University for doing the numerical calculations in this paper on its blade cluster system. W. K. P. is grateful to the financial support by the Australian Research Council through a Future Fellowship project (No. FT160100251)The operational support of ANSTO staffs, especially Dr. Vanessa Peterson and Dr. Christophe Didier, on the collection of neutron powder diffraction data of NaNCMT is highly appreciated. The neutron diffraction data were collected at ANSTO (Australia), CSNS (China), and NIST (USA).
文摘Phase transition is common during (de)-intercalating layered sodium oxides, which directly affects the structural stability and electrochemical performance. However, the artificial control of phase transition to achieve advanced sodium-ion batteries is lacking, since the remarkably little is known about the influencing factor relative to the sliding process of transition-metal slabs upon sodium release and uptake of layered oxides. Herein, we for the first time demonstrate the manipulation of oxygen vacancy concentrations in multinary metallic oxides has a significant impact on the reversibility of phase transition, thereby determining the sodium storage performance of cathode materials. Results show that abundant oxygen vacancies intrigue the return of the already slide transition-metal slabs between O_(3) and P_(3) phase transition, in contrast to the few oxygen vacancies and resulted irreversibility. Additionally, the abundant oxygen vacancies enhance the electronic and ionic conductivity of the Na0.9Ni0.3Co0.15Mn0.05Ti0.5O2 electrode, delivering the high initial Coulombic efficiency of 97.1%, large reversible capacity of 112.7 mAh·g−1, superior rate capability upon 100 C and splendid cycling performance over 1,000 cycles. Our findings open up new horizons for artificially manipulating the structural evolution and electrochemical process of layered cathodes, and pave a way in designing advanced sodium-ion batteries.
基金supported by the Natural Science Foundation of Heilongjiang Province (No. B201307)
文摘For the isomers of amino benzoic acid, including o-, m-, p-amino benzoic acid, the beneficial effects of using the ionic liquid, l-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), as mobile phase additives on retention behavior and separation were investigated. Chromatographic separation of the o-, m-, p-amino benzoic acid was performed on a reversed-phase C18 column by ultraviolet detection at 245 nm. The effects of several chromatographic parameters, concentrations and pH values of [BMIm][BF4] solutions, methanol concentration and length of alkyl chain on different ionic liquids, on the separation and determination of the isomers were evaluated. The optimized chromatographic conditions were established using an aqueous 0.5 mmol/L [BMIm][BF4] solution (pH 3.0)/methanol (40:60, v/v) as mobile phase without need of gradient eiution, with separation of three amino benzoic acids achieved within four min. The calibration curve showed good linearity over the tested range of 2 mg/L to 120 mg/L for the three isomers with a correlation coefficients of 0.9999. The recoveries of the three amino benzoic acids of spiked components were between 99.8% and 100%. The method has been successfully applied to the determination of p-amino benzoic acid in the pharmaceutical, Bromine Mitag Procaine Injection.
基金This work was partially supported by grants fromthe National Basic Research Program (973) of China(2004CB520804), and National Natural Science Foun-dation of China (No. 30270657, 30230150, 3037030).
文摘In this study we systematically analyzed the elution condition of tryptic peptides and the characteristics of identi?ed peptides in reverse phase liquid chromatogra- phy and electrospray tandem mass spectrometry (RPLC-MS/MS) analysis. Fol- lowing protein digestion with trypsin, the peptide mixture was analyzed by on-line RPLC-MS/MS. Bovine serum albumin (BSA) was used to optimize acetonitrile (ACN) elution gradient for tryptic peptides, and Cytochrome C was used to retest the gradient and the sensitivity of LC-MS/MS. The characteristics of identi?ed peptides were also analyzed. In our experiments, the suitable ACN gradient is 5% to 30% for tryptic peptide elution and the sensitivity of LC-MS/MS is 50 fmol. Analysis of the tryptic peptides demonstrated that longer (more than 10 amino acids) and multi-charge state (+2, +3) peptides are likely to be identi?ed, and the hydropathicity of the peptides might not be related to whether it is more likely to be identi?ed or not. The number of identi?ed peptides for a protein might be used to estimate its loading amount under the same sample background. Moreover, in this study the identi?ed peptides present three types of redundancy, namely iden- ti?cation, charge, and sequence redundancy, which may repress low abundance protein identi?cation.
基金financially supported by the National Natural Science Foundation of China(No.22174129)the Natural Science Foundation of Zhejiang Province(No.LZY21E030001)。
文摘Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.