Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1....Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1.5)Cl_(3)]·5H_(2)O}n(2)are framework isomers,which both contain zigzag chains formed by DPA,Zn^(2+),and Cl-.The zigzag chains in 1 are further assembled by C—H…Cl interactions into layers,and these layers exhibit two different orientations,displaying a rare 2D to 3D interpenetration mode.The zigzag chains in 2 are parallelly arranged.{[Zn_(3)(DPA)_(3)Br_(6)]·2DMF·_(1.5)H_(2)O}n(3)is isostructural to 2.3 was obtained using ZnBr_(2)instead of ZnCl_(2).[M(DPA)(formate)_(2)(H_(2)O)_(2)]n[M=Co(4),Cu(5)]are isostructural,contain chain structures formed by DPA,Cu^(2+)/Co^(2+),and for-mate ions,which were formed in situ in the solvothermal reaction.{[Zn(DIP)_(2)Cl]ClO_(4)}n(6)contains a layer structure formed by DIP and Zn^(2+).Free DPA and DIP ligands exhibited high fluorescence at room temperature,and coordina-tion polymers 3 and 6 displayed enhanced fluorescent emissions.展开更多
Fully utilizing renewable biomass energy is important for saving energy,reducing carbon emissions,and mitigating climate change.As the main hydrolysate of cellulose,a primary component of lignocellulose,glucose could ...Fully utilizing renewable biomass energy is important for saving energy,reducing carbon emissions,and mitigating climate change.As the main hydrolysate of cellulose,a primary component of lignocellulose,glucose could be employed as a starting material to prepare some other functional derivatives for improving the value of biomass resources.The isomerization of glucose to produce fructose is an important intermediate process during numerous high-value-added chemical preparations.Therefore,the development of efficient and selective catalysts for glucose isomerization is of great significance.Currently,glucose isomerase catalysts are limited by the harsh conditions required for microbial activity,which restricts further improvements in fructose yield.Additionally,heterogeneous Bronsted-base and Lewis-acid catalysts commonly employed in chemical isomerization methods often lead to the formation of undesirable by-products,resulting in reduced selectivity toward fructose.This study has demonstrated that lithium-loaded heterogeneous catalysts possess excellent isomerization capabilities under mild conditions.A highly efficient Li-C_(3)N_(4) catalyst was developed,achieving a fructose selectivity of 99.9% and a yield of 42.6% at 60℃ within 1.0 h-comparable to the performance of the enzymatic method.Characterization using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),proton nuclear magnetic resonance(^(1)H NMR),and inductively coupled plasma(ICP)analyses confirmed that lithium was stably incorporated into the g-C_(3)N_(4) framework through the formation of Li-N bonds.Further investigations using CO_(2) temperature-programmed desorption(CO_(2)-TPD),in situ Fourier-transform infrared spectroscopy(FT-IR)and 7Li magic angle spinning nuclear magnetic resonance(^(7)Li MAS NMR)indicated that the isomerization proceeded via a base-catalyzed mechanism.The Li species were found to interact with hydroxyl groups generated through hydrolysis and simultaneously coordinated with nitrogen atoms in the C_(3)N_(4) matrix,resulting in the formation of Li-N_(6)-H_(2)O active sites.These active sites facilitated the deprotonation of glucose to form an enolate intermediate,followed by a proton transfer step that generated fructose.This mechanism not only improved the efficiency of fructose production but also provided valuable insight into the catalytic role of lithium within the isomerization process.展开更多
Binuclear complexes have attracted extensive attention in fields such as catalysis because of their likely bimetallic synergistic effect;however,the mechanism and factors influencing this synergism remain unclear.In t...Binuclear complexes have attracted extensive attention in fields such as catalysis because of their likely bimetallic synergistic effect;however,the mechanism and factors influencing this synergism remain unclear.In this work,six bis-β-ketoimine binuclear titanium complexes4a-4f containing different alkylthio sidearms and configurations were synthesized and characterized by nuclear magnetic resonance hydrogen spectrum(~1H-NMR),nuclear magnetic resonance carbon spectrum(^(13)C-NMR),Fourier transform infrared spectrum(FTIR),and elemental analysis.The intermetallic distances of isomeric complexes 4a,4d,4e and 4f determined through density functional theory(DFT)optimization were in the order 4a<4d<4e<4f and were found to significantly influence the catalytic performance for ethylene(co)polymerization.These complexes could efficiently catalyze ethylene polymerization and ethylene/1-hexene or ethylene/1-octene copolymerization with high activity to produce highmolecular-weight ethylene homo-and co-polymers.Among the three binuclear titanium complexes 4a-4c with similar structures but different lengths of alkylthio sidearms,complex 4a,which contained the shortest methylthio sidearm,exhibited the highest activity for ethylene polymerization and copolymerization with 1-hexene or 1-octene.Additionally,for ethylene/1-hexene or ethylene/1-octene copolymerization,it showed the highest comonomer incorporation compared with propylthio(4b)and octylthio(4c)derivatives because of the smaller steric hindrance of the methyl group in 4a and the more open coordination space for vinyl monomers.Furthermore,among the isomeric complexes 4a,4d,4e and4f,complex 4a with the shortest bimetallic distance also exhibited the highest activity towards ethylene(co)polymerization,and the highest 1-hexene or 1-octene incorporation in comparison with its regioisomeric counterparts 4d,4e and p-phenyl-bridged analog 4f,owing to a more appropriate bimetallic distance that is conducive to a synergistic effect.展开更多
In this study,a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid(CA)and mesaconic acid(MA),was incorporated into polymeric networks of poly(N-isopropylacrylamide)(PNIPAM)-based core-shell microgels v...In this study,a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid(CA)and mesaconic acid(MA),was incorporated into polymeric networks of poly(N-isopropylacrylamide)(PNIPAM)-based core-shell microgels via semi-batch precipitation polymerization.We demonstrated that the pH-temperature dual responsiveness of the core-shell microgels is highly correlated with the structure and position of the acid isomers.Both the cis-trans molecular structure and the crosslinking position of the dicarboxylic acids significantly influenced the hydration capacity and surface charge density of the core-shell microgels.These diverse properties first influenced the swelling behavior,further affecting the interfacial behavior of the microgels,including the oil-water dynamic interfacial tension and air-water compression isotherms.Furthermore,the rheological behavior of the microgel suspensions also displayed distinct dependences on the frequency and temperature,illustrating that the cis-trans molecular structure and crosslinked position of the dicarboxylic acids also significantly influenced the interparticle clustering in the bulk solution.Our results suggest that the pH sensitivity of the cis-trans dicarboxylic acid isomer affects the ionization and surface charge distribution of the core or shell layers of individual microgels,which further determines the interparticle interaction and cooperative rearrangement at interfaces and in the bulk.展开更多
We propose a novel scheme for the population and depletion of nuclear isomers.This scheme combines the γ photons with energiesà 10 keV emitted during the interaction of a contemporary high-intensity laser pulse ...We propose a novel scheme for the population and depletion of nuclear isomers.This scheme combines the γ photons with energiesà 10 keV emitted during the interaction of a contemporary high-intensity laser pulse with a plasma and one or multiple photon beams supplied by intense lasers.Owing to nonlinear effects,two-or multiphoton absorption dominates over the conventional multistep one-photon process for an optimized γ flash.Moreover,this nonlinear effect can be greatly enhanced with the help of externally supplied low-energy photons coming from another laser.These low-energy photons act such that the effective cross-section experienced by the γ photons becomes tunable,growing with the intensity I_(0) of the beam.Assuming I_(0)~10^(18) W·cm^(-2) for the photon beam,an effective cross-section as large as 10^(-21)-10^(-28) cm^(2) for the γ photons can be achieved.Thus,with state-of-the-art 10 PW laser facilities,the yields from two-photon absorption can reach 10^(6)-10^(9) isomers per shot for selected states that are separated from their ground state by E2 transitions.Similar yields for transitions with higher multipolarities can be accommodated by multiphoton absorption with additional photons provided.展开更多
BACKGROUND Cirrhosis is a progressive condition characterized by fibrosis that can lead to severe complications and increased mortality.The mac-2 binding protein glyco-sylation isomer(M2BPGi)is a prominent biomarker f...BACKGROUND Cirrhosis is a progressive condition characterized by fibrosis that can lead to severe complications and increased mortality.The mac-2 binding protein glyco-sylation isomer(M2BPGi)is a prominent biomarker for predicting hepatocellular carcinoma(HCC)and cirrhosis-induced esophageal varices(EV).AIM To investigate thresholds of M2BPGi associated with HCC,EV,and decomp-ensation in patients with cirrhosis.METHODS This was a prospective study.A total of 153 patients with cirrhosis who met the inclusion criteria were enrolled.The patients were diagnosed with HCC and EV according to the Baveno VII and European Association for the Study of the Liver guidelines.Baseline serum M2BPGi levels were assessed along with other routine tests.The data analysis aimed to determine the cutoff values of M2BPGi for pre-dicting EV and HCC.RESULTS In the study 85.6%of patients were Child-Pugh B and C.M2BPGi mean cutoff index was 7.1±3.7,showing no significant etiological differences.However,M2BPGi levels varied significantly among Child-Pugh classes,EV classifications,and between patients with and without HCC(P<0.01).M2BPGi cutoff values for predicting HCC,EV,and decompensated cirrhosis were 6.50,6.64,and 5.25,respectively.Mul-tivariate analysis confirmed M2BPGi as an independent risk factor for EV[adjusted odds ratio(aOR):1.3,95%CI:1.08-1.64]and liver decompensation(aOR:2.11,95%CI:1.37-3.83).Area under the curve of M2BPGi for HCC differ-entiation was 0.71.An algorithm combining alpha-fetoprotein(AFP)and M2BPGi detected 26 of 28 HCC cases with 98.04%accuracy vs 10 cases by AFP alone.CONCLUSION Serum M2BPGi predicted cirrhosis complications,including decompensation and varices,especially in HCC.Combined with AFP,it enhanced HCC detection.Future liver biopsy studies are needed for tissue confirmation.展开更多
BACKGROUND Mac-2 binding protein glycosylation isomer(M2BPGi)serves as a marker of activated hepatic stellate cells and as such holds potential as a biomarker for liver fibrosis.In Viet Nam,metabolic dysfunction-assoc...BACKGROUND Mac-2 binding protein glycosylation isomer(M2BPGi)serves as a marker of activated hepatic stellate cells and as such holds potential as a biomarker for liver fibrosis.In Viet Nam,metabolic dysfunction-associated steatotic liver disease(MASLD)is rising in prevalence and there is an urgent need for better clinical management,particularly in early detection methods that will improve overall prognosis.AIM To examine M2BPGi cut-off values for staging liver fibrosis in patients with MASLD and risk factors associated with disease progression.METHODS A total of 301 individuals with ultrasound-confirmed or FibroScan-confirmed diagnosis of fatty liver were enrolled in the study.The participants were stratified according to fibrosis stage,measured via magnetic resonance elastography.M2-BPGi,Fibrosis-4(FIB-4)Index score,and routine parameters of liver function were assessed to statistically investigate the correlation of M2BPGi levels in various fibrosis stages and to identify risk factors associated with fibrosis severity.RESULTS M2BPGi levels positively correlated with fibrosis stages,with cut-off indexes of 0.57 for F0-1,0.68 for F2-3,and 0.78 for F4.M2BPGi levels in the F0-1 group were significantly different from those in both the F2-3 group(P=0.038)and the F4 group(P=0.0051);the F2-3 and F4 groups did not show a significant difference(P=0.39).Females exhibited significantly higher M2BPGi levels than males for all fibrosis stages,particularly in the F2-3 group(P=0.01)and F4 group(P=0.0006).In the F4(cirrhosis)group,individuals with diabetes had significantly higher M2BPGi levels than those without.M2BPGi,hemoglobin A1c,and FIB-4 score were identified as independent risk factors for greater fibrosis and cirrhosis.CONCLUSION M2BPGi levels varied significantly throughout fibrosis progression,from early MASLD to cirrhosis,with sex correlation.M2BPGi holds promise as an early biomarker for fibrosis characterization in MASLD adult patient populations.展开更多
Organic additives with multiple functional groups have shown great promise in improving the performance and stability of perovskite solar cells.The functional groups can passivate undercoordinated ions to reduce nonra...Organic additives with multiple functional groups have shown great promise in improving the performance and stability of perovskite solar cells.The functional groups can passivate undercoordinated ions to reduce nonradiative recombination losses.However,how these groups synergistically affect the enhancement beyond passivation is still unclear.Specifically,isomeric molecules with different substitution patterns or molecular shapes remain elusive in designing new organic additives.Here,we report two isomeric carbazolyl bisphosphonate additives,2,7-Cz BP and 3,6-Cz BP.The isomerism effect on passivation and charge transport process was studied.The two molecules have similar passivation effects through multiple interactions,e.g.,P=O···Pb,P=O···H–N and N–H···I.2,7-CzBP can further bridge the perovskite crystallites to facilitates charge transport.Power conversion efficiencies(PCEs)of 25.88%and 21.04%were achieved for 0.09 cm^(2)devices and 14 cm^(2)modules after 2,7-Cz BP treatment,respectively.The devices exhibited enhanced operational stability maintaining 95%of initial PCE after 1000 h of continuous maximum power point tracking.This study of isomerism effect hints at the importance of tuning substitution positions and molecular shapes for organic additives,which paves the way for innovation of next-generation multifunctional aromatic additives.展开更多
In recent years,the ternary strategy of adding a vip molecule to the active layer has been proven to be effective for improving the performance of organic solar cells(OSCs).Isomerization engineering of the vip mol...In recent years,the ternary strategy of adding a vip molecule to the active layer has been proven to be effective for improving the performance of organic solar cells(OSCs).Isomerization engineering of the vip molecule is a simple method to increase the amount of promising material,but there are only limited reports,and the structure-property relationships are still unclear.In this work,we synthesized three isomers named BTA5-F-o,BTA5-F-m,and BTA5-F-p,with different fluorine substitution positions,to study the influence of isomerization on the photovoltaic performance.After introducing them as the third components to the classic host system PM6:Y6,all three ternary devices showed improved power conversion efficiency(PCEs)compared to the binary system(PCE of 17.46%).The ternary OSCs based on BTA5-F-o achieved a champion PCE of 19.11%,while BTA5-F-m and BTA5-F-p realized PCEs of 18.65%and 18.45%,respectively.Mechanism studies have shown that the dipole moment of the BTA5-F-o end group is closer to that of the Y6 end group,despite the three isomers with almost identical energy levels and optical properties.It is indicated that the electron attraction ability of BTA5-F-o best matches that of Y6,which leads to the higher charge mobility,less charge recombination,and stronger exciton dissociation and extraction ability in the ternary blend system.This study suggests that rationally adjusting the position of substituents in the terminal group can be an effective way to construct nonfullerene vip acceptors to achieve highly efficient ternary OSCs.展开更多
As more and more studies have shown that lipid molecules play an important role in the whole biology,in-depth analysis of lipid structure has become particularly important in lipidomics.Mass spectrometry(MS),as the pr...As more and more studies have shown that lipid molecules play an important role in the whole biology,in-depth analysis of lipid structure has become particularly important in lipidomics.Mass spectrometry(MS),as the preferred tool for lipid analysis,has greatly promoted the development of this field.However,the existing MS methods still face many difficulties in the in-depth or even comprehensive analysis of lipid structure.In this review,we discuss recent advances in MS methods based on double bond-specific chemistries for the resolving of C=C location and geometry isomers of lipids.This progress has greatly advanced the lipidomics analysis to a deeper structural level and facilitated the development of structural lipid biology.展开更多
This study explores the phenomenon of shape coexistence in nuclei around^(172)Hg,with a focus on the isotopes^(170)Pt,^(172)Hg,and^(174)Pb,as well as the^(170)Pt to^(180)Pt isotopic chain.Utilizing a macro-microscopic...This study explores the phenomenon of shape coexistence in nuclei around^(172)Hg,with a focus on the isotopes^(170)Pt,^(172)Hg,and^(174)Pb,as well as the^(170)Pt to^(180)Pt isotopic chain.Utilizing a macro-microscopic approach that incorporates the Lublin-Strasbourg Drop model combined with a Yukawa-Folded potential and pairing corrections,we analyze the potential energy surfaces(PESs)to understand the impact of pairing interaction.For^(170)Pt,the PES exhibited a prolate ground state,with additional triaxial and oblate-shaped isomers.In^(172)Hg,the ground-state deformation transitions from triaxial to oblate with increasing pairing interaction,demonstrating its nearlyγ-unstable nature.Three shape isomers(prolate,triaxial,and oblate)were observed,with increased pairing strength leading to the disappearance of the triaxial isomer.^(174)Pb exhibited a prolate ground state that became increasingly spherical with stronger pairing.While shape isomers were present at lower pairing strengths,robust shape coexistence was not observed.For realistic pairing interaction,the ground-state shapes transitioned from prolate in^(170)Pt to a coexistence ofγ-unstable and oblate shapes in^(172)Hg,ultimately approaching spherical symmetry in^(174)Pb.A comparison between Exact and Bardeen-Cooper-Schrieffer(BCS)pairing demonstrated that BCS pairing tends to smooth out shape coexistence and reduce the depth of the shape isomer,leading to less pronounced deformation features.The PESs for even-even^(170)-180 Pt isotopes revealed significant shape evolution.^(170)Pt showed a prolate ground state,whereas^(172)Pt exhibited both triaxial and prolate shape coexistence.In^(174)Pt,the ground state was triaxial,coexisted with a prolate minimum.For^(176)Pt,aγ-unstable ground state coexists with a prolate minimum.By 178 Pt and 180Pt,a dominant prolate minimum emerged.These results highlight the role of shape coexistence andγ-instability in the evolution of nuclear structure,especially in the mid-shell region.These findings highlight the importance of pairing interactions in nuclear deformation and shape coexistence,providing insights into the structural evolution of mid-shell nuclei.展开更多
The process of deep hydrodesulfurization(HDS)in gasoline typically results in the saturation of olefins,leading to significant reductions in octane number.In this work,Y-supported Co(Ni)-Mo catalysts that with differe...The process of deep hydrodesulfurization(HDS)in gasoline typically results in the saturation of olefins,leading to significant reductions in octane number.In this work,Y-supported Co(Ni)-Mo catalysts that with different Ni-Co content were prepared by the incipient wetness impregnation method,the structure and properties were characterized and analyzed using HRTEM,XPS,H_(2)-TPR,and NH_(3)-TPD.The isomerization of 1-hexene and 1-octene as well as the HDS of thiophene were studied by using model FCC naphtha.The incorporation of Ni was found to enhance the number of MoS_(2) stacking layers,thereby improving the degree of sulfurization in Mo and subsequently increasing the desulfurization rate,with a maximum achieved desulfurization rate of 94.7%.When employing a Ni/Co ratio of 3:2,optimal synergy between Ni and Co is achieved,resulting in a greater presence of multi-layer stacked II-Co(Ni)MoS active phases.Additionally,appropriate Brønsted acidity levels are maintained to facilitate efficient olefin isomerization while preserving high HDS activity.As a result,the current isomerization yield stands at 58.2%(mass).These understandings shed light on the development of highly HDS and olefin isomerization catalysts.展开更多
[Objective] The relationship between three isomers of microcystins and environmental factors were studied in the fields.[Method] Three isomers of microcystins （MC-LR,RR and YR） from water of five sampling spots in a...[Objective] The relationship between three isomers of microcystins and environmental factors were studied in the fields.[Method] Three isomers of microcystins （MC-LR,RR and YR） from water of five sampling spots in a northern reservoir were observed for one year with High Performance Liquid Chromatography analytical method in order to study the relationship between three isomers and environmental factors.[Result] The three isomers of microcystins showed positive correlation with chlorophyll a;LR and YR isomers all had significant linear positive correlations with the water temperature,but the RR isomer showed no significant correlation with the water temperature;LR and YR isomers had relatively significantly correlativities with the contents of total nitrogen,nitrate nitrogen and organic nitrogen,while the RR isomer only showed a significant negative correlation with the content of nitrate nitrogen;LR and RR isomers both showed significant positive correlations with the contents of total phosphorus and organic phosphorus,while the phosphorus hardly affected the YR isomer and showed no evident correlation.[Conclusion] The relationship between three isomers of microcystins and environmental factors such as chlorophyll a,water temperature,nitrogen,phosphorus were studied and investigated the reasons,which might offered a reference for controlling the growth of blue algae in water and toxin synthesis.展开更多
Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible d...Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy,temperature-programmed reduction of H2,temperature-programmed desorption of NH3,infrared spectroscopy of adsorbed pyridine,H2 chemisorption,nitrogen adsorption-desorption,scanning electron microscopy and thermogravimetric analysis were performed.Kinetics of n-C7 isomerization were investigated under various hydrogen and n-C7 pressures,and the effects of reaction conditions on catalytic performance were studied.The results showed that bi-and trimetallic catalysts exhibit better performance than monometallic catalysts for this reaction.For example,a maximum i-C7 selectivity（ 〉74%） and multibranched isomer selectivity（40%） were observed for Pt-Sn/HZSM5-HMS at 200 ℃.展开更多
Hierarchical SAPO-11 molecular sieve(ACS-11) was successfully synthesized employing the Al2O3/carbon(Al_(2)O_(3)/C) composite obtained through the pyrolysis of Al-based metal-organic framework(Al-MOF-96)as mesoporogen...Hierarchical SAPO-11 molecular sieve(ACS-11) was successfully synthesized employing the Al2O3/carbon(Al_(2)O_(3)/C) composite obtained through the pyrolysis of Al-based metal-organic framework(Al-MOF-96)as mesoporogen.Unlike other carbon-based mesoporogens with strong hydrophobicity,the Al_(2)O_(3)/C interacts with phosphoric acid and generates the AlPO_(4)/C structure,which promotes the Al2O3/C dispersion in the synthesis gel of SAPO-11 and avoids the phase separation between them.The Al_(2)O_(3)/C as mesoporogen decreases the crystallite size of SAPO-11 via preventing the aggregation of SAPO-11crystals.Additionally,the addition of Al_(2)O_(3)/C improves the Si distribution in the ACS-11 framework.Consequently,ACS-11 has smaller crystallites,more mesopores,and a greater amount of medium Bronsted acid centers than the conventional microporous SAPO-11 and the SAPO-11 synthesized using activated carbon as mesoporogen.The corresponding Pt/ACS-11 catalyst exhibits the maximal selectivity to multi-branched C10isomers(23.28%) and the minimal cracking selectivity(15.83%) in n-decane hydroisomerization among these catalysts.This research provides a new approach for preparing hierarchical silicoaluminophosphate molecular sieve-based catalysts to produce high-quality fuels.展开更多
Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-[E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-...Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-[E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-dimethyl-2,5-dihydrofuran （FTC） in a few solvents have been studied using the time-dependent density functional theory in combination with the polarizable continuum model. It is shown that the maximum absorption peaks of the ro-tamers have difference of nearly 30 nm both in vacuum and in solutions. The population of the rotamers changes a lot in different solvents. Based on the geometries optimized by Hartree-Fock method, the Maxwell-Boltzmann averaged absorption has been calculated and the maximum absorption peak is in good agreement with experiment. It indicates that the bond length alternation can have an important effect on the optical spectra.展开更多
To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepa...To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.展开更多
DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with differ...DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with different nitrate and phosphate concentrations were analysed by HPLC with Alox-Talumins column. At least six isomers were found in different proportions depending on the culture me-dia’s nitrate and/or phosphate concentrations. Nitrate and/or phosphae defidency was conducive tothe accumulation of totaI cis isomers but not of al1 trans isomer. lt is sUggeSted that 1 mmol/L KNO<sub>3</sub>and 0.1 mmol/L KH<sub>2</sub>, PO<sub>4</sub> are favourable for accumulation of total cis β-carotene.展开更多
Two new isomers of HPS3 system, HP(S)S2 and HSSPS, are predicted by means of B3LYP method with 6-311++G(3df,3pd) basis set. The two isomers can isomerize into thermodynamically the most stable species HSPS2, which ha...Two new isomers of HPS3 system, HP(S)S2 and HSSPS, are predicted by means of B3LYP method with 6-311++G(3df,3pd) basis set. The two isomers can isomerize into thermodynamically the most stable species HSPS2, which have been experimentally identified, with relatively higher reaction barriers. In view of their higher thermodynamical and kinetic stability and the experimental observation for HP(O)O2 and HOOPO in previous study, we can reasonably believe that the two species can be spectrosymmetrically characterized in future experiments.展开更多
Aims:Evidence is emerging that,in the setting of isomerism,the atrial and bronchial arrangement are not always concordant,nor are these patterns always harmonious with the arrangement of the abdominal organs.We aimed ...Aims:Evidence is emerging that,in the setting of isomerism,the atrial and bronchial arrangement are not always concordant,nor are these patterns always harmonious with the arrangement of the abdominal organs.We aimed to evaluate the concordance between these features in a cohort of patients with cardiac malformations in the setting of known isomerism,seeking to determine whether it was feasible to assess complexity on this basis,in this regard taking note of the potential value of bronchial as opposed to appendage morphology.Methods and Results:We studied 78 patients known to have isomerism of the bronchuses,43 with right and 35 with left isomerism.Appendage anatomy could be determined in 49 cases(63%),all but one of these being concordant with bronchial anatomy.When assessing abdominal features,in only 59 cases(76%)was splenic morphology in keeping with the thoracic findings.As expected,right isomerism was associated with greater complexity of cardiac malformations,with an odds ratio of 6.53,with confidence intervals from 2.2–19.3(p<0.001).The odds were slightly decreased with thoraco-abdominal disharmony,when lesions shown to carry higher risk were then found in the setting of left isomerism.Conclusion:Harmony is excellent between bronchial and appendage isomerism,but less so with the arrangement of the abdominal organs.Right isomerism in our cohort,was indicative of a sixfold increase in intracardiac complexity.When discordance was found between the systems,however,the cardiac anomalies were less typical of the anticipated findings for right vs.left isomerism of the appendages.展开更多
文摘Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1.5)Cl_(3)]·5H_(2)O}n(2)are framework isomers,which both contain zigzag chains formed by DPA,Zn^(2+),and Cl-.The zigzag chains in 1 are further assembled by C—H…Cl interactions into layers,and these layers exhibit two different orientations,displaying a rare 2D to 3D interpenetration mode.The zigzag chains in 2 are parallelly arranged.{[Zn_(3)(DPA)_(3)Br_(6)]·2DMF·_(1.5)H_(2)O}n(3)is isostructural to 2.3 was obtained using ZnBr_(2)instead of ZnCl_(2).[M(DPA)(formate)_(2)(H_(2)O)_(2)]n[M=Co(4),Cu(5)]are isostructural,contain chain structures formed by DPA,Cu^(2+)/Co^(2+),and for-mate ions,which were formed in situ in the solvothermal reaction.{[Zn(DIP)_(2)Cl]ClO_(4)}n(6)contains a layer structure formed by DIP and Zn^(2+).Free DPA and DIP ligands exhibited high fluorescence at room temperature,and coordina-tion polymers 3 and 6 displayed enhanced fluorescent emissions.
基金supported by the National Natural Science Foundation of China(22278419)the Key Core Technology Research(Social Development)Foundation of Suzhou(2023ss06)the Suzhou National Joint Laboratory for Green and Low-carbon Wastewater Treatment and Resource Utilization Technology,Suzhou University of Science and Technology(SZLSDT202404).
文摘Fully utilizing renewable biomass energy is important for saving energy,reducing carbon emissions,and mitigating climate change.As the main hydrolysate of cellulose,a primary component of lignocellulose,glucose could be employed as a starting material to prepare some other functional derivatives for improving the value of biomass resources.The isomerization of glucose to produce fructose is an important intermediate process during numerous high-value-added chemical preparations.Therefore,the development of efficient and selective catalysts for glucose isomerization is of great significance.Currently,glucose isomerase catalysts are limited by the harsh conditions required for microbial activity,which restricts further improvements in fructose yield.Additionally,heterogeneous Bronsted-base and Lewis-acid catalysts commonly employed in chemical isomerization methods often lead to the formation of undesirable by-products,resulting in reduced selectivity toward fructose.This study has demonstrated that lithium-loaded heterogeneous catalysts possess excellent isomerization capabilities under mild conditions.A highly efficient Li-C_(3)N_(4) catalyst was developed,achieving a fructose selectivity of 99.9% and a yield of 42.6% at 60℃ within 1.0 h-comparable to the performance of the enzymatic method.Characterization using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),proton nuclear magnetic resonance(^(1)H NMR),and inductively coupled plasma(ICP)analyses confirmed that lithium was stably incorporated into the g-C_(3)N_(4) framework through the formation of Li-N bonds.Further investigations using CO_(2) temperature-programmed desorption(CO_(2)-TPD),in situ Fourier-transform infrared spectroscopy(FT-IR)and 7Li magic angle spinning nuclear magnetic resonance(^(7)Li MAS NMR)indicated that the isomerization proceeded via a base-catalyzed mechanism.The Li species were found to interact with hydroxyl groups generated through hydrolysis and simultaneously coordinated with nitrogen atoms in the C_(3)N_(4) matrix,resulting in the formation of Li-N_(6)-H_(2)O active sites.These active sites facilitated the deprotonation of glucose to form an enolate intermediate,followed by a proton transfer step that generated fructose.This mechanism not only improved the efficiency of fructose production but also provided valuable insight into the catalytic role of lithium within the isomerization process.
基金financially supported by the National Natural Science Foundation of China(No.21172269)the Fundamental Research Funds for the Central Universities,SouthCentral Minzu University(No.CZH24005)。
文摘Binuclear complexes have attracted extensive attention in fields such as catalysis because of their likely bimetallic synergistic effect;however,the mechanism and factors influencing this synergism remain unclear.In this work,six bis-β-ketoimine binuclear titanium complexes4a-4f containing different alkylthio sidearms and configurations were synthesized and characterized by nuclear magnetic resonance hydrogen spectrum(~1H-NMR),nuclear magnetic resonance carbon spectrum(^(13)C-NMR),Fourier transform infrared spectrum(FTIR),and elemental analysis.The intermetallic distances of isomeric complexes 4a,4d,4e and 4f determined through density functional theory(DFT)optimization were in the order 4a<4d<4e<4f and were found to significantly influence the catalytic performance for ethylene(co)polymerization.These complexes could efficiently catalyze ethylene polymerization and ethylene/1-hexene or ethylene/1-octene copolymerization with high activity to produce highmolecular-weight ethylene homo-and co-polymers.Among the three binuclear titanium complexes 4a-4c with similar structures but different lengths of alkylthio sidearms,complex 4a,which contained the shortest methylthio sidearm,exhibited the highest activity for ethylene polymerization and copolymerization with 1-hexene or 1-octene.Additionally,for ethylene/1-hexene or ethylene/1-octene copolymerization,it showed the highest comonomer incorporation compared with propylthio(4b)and octylthio(4c)derivatives because of the smaller steric hindrance of the methyl group in 4a and the more open coordination space for vinyl monomers.Furthermore,among the isomeric complexes 4a,4d,4e and4f,complex 4a with the shortest bimetallic distance also exhibited the highest activity towards ethylene(co)polymerization,and the highest 1-hexene or 1-octene incorporation in comparison with its regioisomeric counterparts 4d,4e and p-phenyl-bridged analog 4f,owing to a more appropriate bimetallic distance that is conducive to a synergistic effect.
基金financially supported by the National Natural Science Foundation of China(No.22303033)the Fundamental Research Funds for the Central Universities,China(No.JUSRP123017)+1 种基金Wuxi“Taihu Light”Science and Technology Project-Basic Research(No.K20231063)the Research Matching Grant Scheme at CUHK(No.8601309)。
文摘In this study,a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid(CA)and mesaconic acid(MA),was incorporated into polymeric networks of poly(N-isopropylacrylamide)(PNIPAM)-based core-shell microgels via semi-batch precipitation polymerization.We demonstrated that the pH-temperature dual responsiveness of the core-shell microgels is highly correlated with the structure and position of the acid isomers.Both the cis-trans molecular structure and the crosslinking position of the dicarboxylic acids significantly influenced the hydration capacity and surface charge density of the core-shell microgels.These diverse properties first influenced the swelling behavior,further affecting the interfacial behavior of the microgels,including the oil-water dynamic interfacial tension and air-water compression isotherms.Furthermore,the rheological behavior of the microgel suspensions also displayed distinct dependences on the frequency and temperature,illustrating that the cis-trans molecular structure and crosslinked position of the dicarboxylic acids also significantly influenced the interparticle clustering in the bulk solution.Our results suggest that the pH sensitivity of the cis-trans dicarboxylic acid isomer affects the ionization and surface charge distribution of the core or shell layers of individual microgels,which further determines the interparticle interaction and cooperative rearrangement at interfaces and in the bulk.
基金supported by the Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase Ⅱ,a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund—the Competitiveness Operational Programme(1/07.07.2016,COP,ID 1334)the Romanian Ministry of Research and Innovation:PN23210105(Phase 2,the Program Nucleu),ELI-RO grants Proiectul ELI-RO/RDI_2024_AMAP,ELI-RO_RDI_2024_LaLuThe,ELIRO_RDI_2024_SPARC+4 种基金ELI10/01.10.2020 of the Romanian Governmentthe European Union,the Romanian Governmentthe Health Program,within the project“Medical Applications of High-Power Lasers—Dr.LASER”SMIS Code:326475the IOSIN funds for research infrastructures of national interest.
文摘We propose a novel scheme for the population and depletion of nuclear isomers.This scheme combines the γ photons with energiesà 10 keV emitted during the interaction of a contemporary high-intensity laser pulse with a plasma and one or multiple photon beams supplied by intense lasers.Owing to nonlinear effects,two-or multiphoton absorption dominates over the conventional multistep one-photon process for an optimized γ flash.Moreover,this nonlinear effect can be greatly enhanced with the help of externally supplied low-energy photons coming from another laser.These low-energy photons act such that the effective cross-section experienced by the γ photons becomes tunable,growing with the intensity I_(0) of the beam.Assuming I_(0)~10^(18) W·cm^(-2) for the photon beam,an effective cross-section as large as 10^(-21)-10^(-28) cm^(2) for the γ photons can be achieved.Thus,with state-of-the-art 10 PW laser facilities,the yields from two-photon absorption can reach 10^(6)-10^(9) isomers per shot for selected states that are separated from their ground state by E2 transitions.Similar yields for transitions with higher multipolarities can be accommodated by multiphoton absorption with additional photons provided.
文摘BACKGROUND Cirrhosis is a progressive condition characterized by fibrosis that can lead to severe complications and increased mortality.The mac-2 binding protein glyco-sylation isomer(M2BPGi)is a prominent biomarker for predicting hepatocellular carcinoma(HCC)and cirrhosis-induced esophageal varices(EV).AIM To investigate thresholds of M2BPGi associated with HCC,EV,and decomp-ensation in patients with cirrhosis.METHODS This was a prospective study.A total of 153 patients with cirrhosis who met the inclusion criteria were enrolled.The patients were diagnosed with HCC and EV according to the Baveno VII and European Association for the Study of the Liver guidelines.Baseline serum M2BPGi levels were assessed along with other routine tests.The data analysis aimed to determine the cutoff values of M2BPGi for pre-dicting EV and HCC.RESULTS In the study 85.6%of patients were Child-Pugh B and C.M2BPGi mean cutoff index was 7.1±3.7,showing no significant etiological differences.However,M2BPGi levels varied significantly among Child-Pugh classes,EV classifications,and between patients with and without HCC(P<0.01).M2BPGi cutoff values for predicting HCC,EV,and decompensated cirrhosis were 6.50,6.64,and 5.25,respectively.Mul-tivariate analysis confirmed M2BPGi as an independent risk factor for EV[adjusted odds ratio(aOR):1.3,95%CI:1.08-1.64]and liver decompensation(aOR:2.11,95%CI:1.37-3.83).Area under the curve of M2BPGi for HCC differ-entiation was 0.71.An algorithm combining alpha-fetoprotein(AFP)and M2BPGi detected 26 of 28 HCC cases with 98.04%accuracy vs 10 cases by AFP alone.CONCLUSION Serum M2BPGi predicted cirrhosis complications,including decompensation and varices,especially in HCC.Combined with AFP,it enhanced HCC detection.Future liver biopsy studies are needed for tissue confirmation.
文摘BACKGROUND Mac-2 binding protein glycosylation isomer(M2BPGi)serves as a marker of activated hepatic stellate cells and as such holds potential as a biomarker for liver fibrosis.In Viet Nam,metabolic dysfunction-associated steatotic liver disease(MASLD)is rising in prevalence and there is an urgent need for better clinical management,particularly in early detection methods that will improve overall prognosis.AIM To examine M2BPGi cut-off values for staging liver fibrosis in patients with MASLD and risk factors associated with disease progression.METHODS A total of 301 individuals with ultrasound-confirmed or FibroScan-confirmed diagnosis of fatty liver were enrolled in the study.The participants were stratified according to fibrosis stage,measured via magnetic resonance elastography.M2-BPGi,Fibrosis-4(FIB-4)Index score,and routine parameters of liver function were assessed to statistically investigate the correlation of M2BPGi levels in various fibrosis stages and to identify risk factors associated with fibrosis severity.RESULTS M2BPGi levels positively correlated with fibrosis stages,with cut-off indexes of 0.57 for F0-1,0.68 for F2-3,and 0.78 for F4.M2BPGi levels in the F0-1 group were significantly different from those in both the F2-3 group(P=0.038)and the F4 group(P=0.0051);the F2-3 and F4 groups did not show a significant difference(P=0.39).Females exhibited significantly higher M2BPGi levels than males for all fibrosis stages,particularly in the F2-3 group(P=0.01)and F4 group(P=0.0006).In the F4(cirrhosis)group,individuals with diabetes had significantly higher M2BPGi levels than those without.M2BPGi,hemoglobin A1c,and FIB-4 score were identified as independent risk factors for greater fibrosis and cirrhosis.CONCLUSION M2BPGi levels varied significantly throughout fibrosis progression,from early MASLD to cirrhosis,with sex correlation.M2BPGi holds promise as an early biomarker for fibrosis characterization in MASLD adult patient populations.
基金financially supported by the National Science Foundation of China(62474142)Natural Science Foundation of Shandong Province(No.ZR2024YQ070)。
文摘Organic additives with multiple functional groups have shown great promise in improving the performance and stability of perovskite solar cells.The functional groups can passivate undercoordinated ions to reduce nonradiative recombination losses.However,how these groups synergistically affect the enhancement beyond passivation is still unclear.Specifically,isomeric molecules with different substitution patterns or molecular shapes remain elusive in designing new organic additives.Here,we report two isomeric carbazolyl bisphosphonate additives,2,7-Cz BP and 3,6-Cz BP.The isomerism effect on passivation and charge transport process was studied.The two molecules have similar passivation effects through multiple interactions,e.g.,P=O···Pb,P=O···H–N and N–H···I.2,7-CzBP can further bridge the perovskite crystallites to facilitates charge transport.Power conversion efficiencies(PCEs)of 25.88%and 21.04%were achieved for 0.09 cm^(2)devices and 14 cm^(2)modules after 2,7-Cz BP treatment,respectively.The devices exhibited enhanced operational stability maintaining 95%of initial PCE after 1000 h of continuous maximum power point tracking.This study of isomerism effect hints at the importance of tuning substitution positions and molecular shapes for organic additives,which paves the way for innovation of next-generation multifunctional aromatic additives.
基金support from the National Natural Science Foundation of China(62204146,52303259)the Start-up Grant of Henan University of Technology(2023BS035)。
文摘In recent years,the ternary strategy of adding a vip molecule to the active layer has been proven to be effective for improving the performance of organic solar cells(OSCs).Isomerization engineering of the vip molecule is a simple method to increase the amount of promising material,but there are only limited reports,and the structure-property relationships are still unclear.In this work,we synthesized three isomers named BTA5-F-o,BTA5-F-m,and BTA5-F-p,with different fluorine substitution positions,to study the influence of isomerization on the photovoltaic performance.After introducing them as the third components to the classic host system PM6:Y6,all three ternary devices showed improved power conversion efficiency(PCEs)compared to the binary system(PCE of 17.46%).The ternary OSCs based on BTA5-F-o achieved a champion PCE of 19.11%,while BTA5-F-m and BTA5-F-p realized PCEs of 18.65%and 18.45%,respectively.Mechanism studies have shown that the dipole moment of the BTA5-F-o end group is closer to that of the Y6 end group,despite the three isomers with almost identical energy levels and optical properties.It is indicated that the electron attraction ability of BTA5-F-o best matches that of Y6,which leads to the higher charge mobility,less charge recombination,and stronger exciton dissociation and extraction ability in the ternary blend system.This study suggests that rationally adjusting the position of substituents in the terminal group can be an effective way to construct nonfullerene vip acceptors to achieve highly efficient ternary OSCs.
基金financially supported by the National Natural Science Foundation of China(No.22074111)National Key Research and Development Program of China(No.2021YFC2700700)the Opening fund of Hubei Key Laboratory of Bioinorganic Chemistry&Materia Medica(No.BCMM202303)。
文摘As more and more studies have shown that lipid molecules play an important role in the whole biology,in-depth analysis of lipid structure has become particularly important in lipidomics.Mass spectrometry(MS),as the preferred tool for lipid analysis,has greatly promoted the development of this field.However,the existing MS methods still face many difficulties in the in-depth or even comprehensive analysis of lipid structure.In this review,we discuss recent advances in MS methods based on double bond-specific chemistries for the resolving of C=C location and geometry isomers of lipids.This progress has greatly advanced the lipidomics analysis to a deeper structural level and facilitated the development of structural lipid biology.
基金supported by the National Natural Science Foundation of China(Nos.12275115 and 12175097)the National Science Centre of Poland(No.2023/49/B/ST2/01294).
文摘This study explores the phenomenon of shape coexistence in nuclei around^(172)Hg,with a focus on the isotopes^(170)Pt,^(172)Hg,and^(174)Pb,as well as the^(170)Pt to^(180)Pt isotopic chain.Utilizing a macro-microscopic approach that incorporates the Lublin-Strasbourg Drop model combined with a Yukawa-Folded potential and pairing corrections,we analyze the potential energy surfaces(PESs)to understand the impact of pairing interaction.For^(170)Pt,the PES exhibited a prolate ground state,with additional triaxial and oblate-shaped isomers.In^(172)Hg,the ground-state deformation transitions from triaxial to oblate with increasing pairing interaction,demonstrating its nearlyγ-unstable nature.Three shape isomers(prolate,triaxial,and oblate)were observed,with increased pairing strength leading to the disappearance of the triaxial isomer.^(174)Pb exhibited a prolate ground state that became increasingly spherical with stronger pairing.While shape isomers were present at lower pairing strengths,robust shape coexistence was not observed.For realistic pairing interaction,the ground-state shapes transitioned from prolate in^(170)Pt to a coexistence ofγ-unstable and oblate shapes in^(172)Hg,ultimately approaching spherical symmetry in^(174)Pb.A comparison between Exact and Bardeen-Cooper-Schrieffer(BCS)pairing demonstrated that BCS pairing tends to smooth out shape coexistence and reduce the depth of the shape isomer,leading to less pronounced deformation features.The PESs for even-even^(170)-180 Pt isotopes revealed significant shape evolution.^(170)Pt showed a prolate ground state,whereas^(172)Pt exhibited both triaxial and prolate shape coexistence.In^(174)Pt,the ground state was triaxial,coexisted with a prolate minimum.For^(176)Pt,aγ-unstable ground state coexists with a prolate minimum.By 178 Pt and 180Pt,a dominant prolate minimum emerged.These results highlight the role of shape coexistence andγ-instability in the evolution of nuclear structure,especially in the mid-shell region.These findings highlight the importance of pairing interactions in nuclear deformation and shape coexistence,providing insights into the structural evolution of mid-shell nuclei.
基金supported by the National Natural Science Foundation of China(U22B20140,22021004,22325808,22393950)the National Key Research and Development Program of China(2020YFA0210900).
文摘The process of deep hydrodesulfurization(HDS)in gasoline typically results in the saturation of olefins,leading to significant reductions in octane number.In this work,Y-supported Co(Ni)-Mo catalysts that with different Ni-Co content were prepared by the incipient wetness impregnation method,the structure and properties were characterized and analyzed using HRTEM,XPS,H_(2)-TPR,and NH_(3)-TPD.The isomerization of 1-hexene and 1-octene as well as the HDS of thiophene were studied by using model FCC naphtha.The incorporation of Ni was found to enhance the number of MoS_(2) stacking layers,thereby improving the degree of sulfurization in Mo and subsequently increasing the desulfurization rate,with a maximum achieved desulfurization rate of 94.7%.When employing a Ni/Co ratio of 3:2,optimal synergy between Ni and Co is achieved,resulting in a greater presence of multi-layer stacked II-Co(Ni)MoS active phases.Additionally,appropriate Brønsted acidity levels are maintained to facilitate efficient olefin isomerization while preserving high HDS activity.As a result,the current isomerization yield stands at 58.2%(mass).These understandings shed light on the development of highly HDS and olefin isomerization catalysts.
基金Supported by Technical Innovation Project of Ministry of Water Conservancy(SCX2002-04)National Nature Science Foundation of China(50579015)~~
文摘[Objective] The relationship between three isomers of microcystins and environmental factors were studied in the fields.[Method] Three isomers of microcystins （MC-LR,RR and YR） from water of five sampling spots in a northern reservoir were observed for one year with High Performance Liquid Chromatography analytical method in order to study the relationship between three isomers and environmental factors.[Result] The three isomers of microcystins showed positive correlation with chlorophyll a;LR and YR isomers all had significant linear positive correlations with the water temperature,but the RR isomer showed no significant correlation with the water temperature;LR and YR isomers had relatively significantly correlativities with the contents of total nitrogen,nitrate nitrogen and organic nitrogen,while the RR isomer only showed a significant negative correlation with the content of nitrate nitrogen;LR and RR isomers both showed significant positive correlations with the contents of total phosphorus and organic phosphorus,while the phosphorus hardly affected the YR isomer and showed no evident correlation.[Conclusion] The relationship between three isomers of microcystins and environmental factors such as chlorophyll a,water temperature,nitrogen,phosphorus were studied and investigated the reasons,which might offered a reference for controlling the growth of blue algae in water and toxin synthesis.
文摘Pt-（Sn,Re）/HZSM5-HMS catalysts were evaluated for n-heptane isomerization at 200–350 ℃.To characterize the catalyst,X-ray diffraction,X-ray fluorescene,Fourier transform infrared spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy,temperature-programmed reduction of H2,temperature-programmed desorption of NH3,infrared spectroscopy of adsorbed pyridine,H2 chemisorption,nitrogen adsorption-desorption,scanning electron microscopy and thermogravimetric analysis were performed.Kinetics of n-C7 isomerization were investigated under various hydrogen and n-C7 pressures,and the effects of reaction conditions on catalytic performance were studied.The results showed that bi-and trimetallic catalysts exhibit better performance than monometallic catalysts for this reaction.For example,a maximum i-C7 selectivity（ 〉74%） and multibranched isomer selectivity（40%） were observed for Pt-Sn/HZSM5-HMS at 200 ℃.
基金financial support of Science Foundation of China University of Petroleum,Beijing(Grant No.KYJJ2012-03-03)
文摘Hierarchical SAPO-11 molecular sieve(ACS-11) was successfully synthesized employing the Al2O3/carbon(Al_(2)O_(3)/C) composite obtained through the pyrolysis of Al-based metal-organic framework(Al-MOF-96)as mesoporogen.Unlike other carbon-based mesoporogens with strong hydrophobicity,the Al_(2)O_(3)/C interacts with phosphoric acid and generates the AlPO_(4)/C structure,which promotes the Al2O3/C dispersion in the synthesis gel of SAPO-11 and avoids the phase separation between them.The Al_(2)O_(3)/C as mesoporogen decreases the crystallite size of SAPO-11 via preventing the aggregation of SAPO-11crystals.Additionally,the addition of Al_(2)O_(3)/C improves the Si distribution in the ACS-11 framework.Consequently,ACS-11 has smaller crystallites,more mesopores,and a greater amount of medium Bronsted acid centers than the conventional microporous SAPO-11 and the SAPO-11 synthesized using activated carbon as mesoporogen.The corresponding Pt/ACS-11 catalyst exhibits the maximal selectivity to multi-branched C10isomers(23.28%) and the minimal cracking selectivity(15.83%) in n-decane hydroisomerization among these catalysts.This research provides a new approach for preparing hierarchical silicoaluminophosphate molecular sieve-based catalysts to produce high-quality fuels.
基金ACKNOWLEDGMENTS This work was supported by Young Scientists Fund of the National Natural Science Foundation of China （No.10904085）.
文摘Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-[E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-dimethyl-2,5-dihydrofuran （FTC） in a few solvents have been studied using the time-dependent density functional theory in combination with the polarizable continuum model. It is shown that the maximum absorption peaks of the ro-tamers have difference of nearly 30 nm both in vacuum and in solutions. The population of the rotamers changes a lot in different solvents. Based on the geometries optimized by Hartree-Fock method, the Maxwell-Boltzmann averaged absorption has been calculated and the maximum absorption peak is in good agreement with experiment. It indicates that the bond length alternation can have an important effect on the optical spectra.
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China(Grant No.21978323)。
文摘To enhance the gasoline octane number,low-octane linear n-alkanes should be converted into their high-octane di-branched isomers via n-alkane hydroisomerization.Therefore,hierarchical SAPO-11-based catalysts are prepared by adding different contents of sodium dodecylbenzene sulfonate(SDBS),and they are applied in n-nonane hydroisomerization.When n(SDBS)/n(SiO2)is less than or equal to 0.125,the synthesized hierarchical molecular sieves are all pure SAPO-11,and as the SDBS content increases,the submicron particle size decreases,and the external surface area(ESA)increases.Additionally,these hierarchical SAPO-11 have smaller submicron particles and higher ESA values than conventional SAPO-11.When n(SDBS)/n(SiO2)is greater than 0.125,with increasing SDBS content(n(SDBS)/n(SiO2)=0.25),the synthesized SAPO-11 contains amorphous materials,which leads to a decline in the ESA;with the further increase in SDBS content(n(SDBS)/n(SiO2)=0.5),the products are all amorphous materials.These results indicate that in the case of n(SDBS)/n(SiO2)=0.125,the synthesized SAPO-11 molecular sieve(S–S3)has the most external Brønsted acid centers and the highest ESA of these SAPO-11,and these advantages favor generation of the di-branched isomers in hydrocarbon hydroisomerization.Among these Pt/SAPO-11 catalysts,Pt/S–S3 displays the highest selectivity to entire isomers(83.4%),the highest selectivity to di-branched isomers(28.1%)and the minimum hydrocracking selectivity(15.7%)in n-nonane hydroisomerization.
基金This project was supported by the National Natural Science Foundation of China,Grant No.38970587.
文摘DunaIiella salina, a halotolerent unicellular green alga, can accurmulate a Iarge amount of β-caroteneunder environmental conditions. The isorners of β-carotene extIacted from D. salina culturedin medium with different nitrate and phosphate concentrations were analysed by HPLC with Alox-Talumins column. At least six isomers were found in different proportions depending on the culture me-dia’s nitrate and/or phosphate concentrations. Nitrate and/or phosphae defidency was conducive tothe accumulation of totaI cis isomers but not of al1 trans isomer. lt is sUggeSted that 1 mmol/L KNO<sub>3</sub>and 0.1 mmol/L KH<sub>2</sub>, PO<sub>4</sub> are favourable for accumulation of total cis β-carotene.
基金This work is supported by the National Natural Science Foundation of China(No.20171016,20271019)the Natural Science Foundation of Heilongjiang Province of China(No.E00-16)+1 种基金the Doctoral Start-up Foundation of Heilongjiang University(2002)the Science Foundation for Excellent Youth of Heilongjiang University(J200106).
文摘Two new isomers of HPS3 system, HP(S)S2 and HSSPS, are predicted by means of B3LYP method with 6-311++G(3df,3pd) basis set. The two isomers can isomerize into thermodynamically the most stable species HSPS2, which have been experimentally identified, with relatively higher reaction barriers. In view of their higher thermodynamical and kinetic stability and the experimental observation for HP(O)O2 and HOOPO in previous study, we can reasonably believe that the two species can be spectrosymmetrically characterized in future experiments.
文摘Aims:Evidence is emerging that,in the setting of isomerism,the atrial and bronchial arrangement are not always concordant,nor are these patterns always harmonious with the arrangement of the abdominal organs.We aimed to evaluate the concordance between these features in a cohort of patients with cardiac malformations in the setting of known isomerism,seeking to determine whether it was feasible to assess complexity on this basis,in this regard taking note of the potential value of bronchial as opposed to appendage morphology.Methods and Results:We studied 78 patients known to have isomerism of the bronchuses,43 with right and 35 with left isomerism.Appendage anatomy could be determined in 49 cases(63%),all but one of these being concordant with bronchial anatomy.When assessing abdominal features,in only 59 cases(76%)was splenic morphology in keeping with the thoracic findings.As expected,right isomerism was associated with greater complexity of cardiac malformations,with an odds ratio of 6.53,with confidence intervals from 2.2–19.3(p<0.001).The odds were slightly decreased with thoraco-abdominal disharmony,when lesions shown to carry higher risk were then found in the setting of left isomerism.Conclusion:Harmony is excellent between bronchial and appendage isomerism,but less so with the arrangement of the abdominal organs.Right isomerism in our cohort,was indicative of a sixfold increase in intracardiac complexity.When discordance was found between the systems,however,the cardiac anomalies were less typical of the anticipated findings for right vs.left isomerism of the appendages.
