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
The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and...The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of drugs.Nowadays,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose isomerase.Some low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and HFCS.However,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare sugars.Considering the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial products.In this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.展开更多
In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photo...In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.展开更多
The reaction of 7-amino-4-methyl-2(1H)-quinolone 1 and its 6-methyl derivative 2 with Vilsmeier reagent (DMF and POCl3) afforded 7-[1-aza-2-(dimethylamino)vinyl]-4-methyl-hydroquinolin-2-one 3 and 7-[1-aza-2-(dimethyl...The reaction of 7-amino-4-methyl-2(1H)-quinolone 1 and its 6-methyl derivative 2 with Vilsmeier reagent (DMF and POCl3) afforded 7-[1-aza-2-(dimethylamino)vinyl]-4-methyl-hydroquinolin-2-one 3 and 7-[1-aza-2-(dimethylamino)vinyl]-4,6-dimethylhydroquinolin- 2-one 4, respec-tively. H-1-NMR analysis in different solvents indicated that isomerism occurred due to hindered rotation around the (CH3)(2)N-C:N o -bond. The rotational energy barrier of 3 was calculated.展开更多
One-photon absorption and two-photon absorption(TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polar...One-photon absorption and two-photon absorption(TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model.The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer(ICT)properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.展开更多
The influence of rotational isomerism on the two-photon absorption (TPA) of FTC chromophores has been investi- gated using the quadratic response theory with the B3LYP functional. Eight rotamers induced by three rot...The influence of rotational isomerism on the two-photon absorption (TPA) of FTC chromophores has been investi- gated using the quadratic response theory with the B3LYP functional. Eight rotamers induced by three rotatable single bonds in the molecule are fully optimized, and it is found that their conformational energies are nearly degenerate. Our calculations demonstrate that rotational isomerism has an important effect on the TPA cross sections. For a certain rotamer, the maximum TPA cross section is enhanced significantly. In addition, in the longer wavelength region, the rotational isomerism could lead to a large shift of the TPA position.展开更多
In this study,we theoretically investigate the feasibility of using laser-wakefield accelerated(LWFA)electrons for the photonuclear measurement of nuclear isomers according to the characteristics of the electrons obta...In this study,we theoretically investigate the feasibility of using laser-wakefield accelerated(LWFA)electrons for the photonuclear measurement of nuclear isomers according to the characteristics of the electrons obtained from LWFA experiments conducted at the Compact Laser-Plasma Accelerator(CLAPA)laboratory.The experiments at the CLAPA show that a stable electron beam with an energy of 78-135 MeV and a charge of 300-600 pC can be obtained.The bremsstrahlung spectra were simulated using Geant4,which suggests that a bremsstrahlung source with a peak intensity of 10^(19) photons/s can be generated.Theoretical calculations of isomer production cross sections from the photonuclear reactions on six target nuclei,^(197)Au,^(180)Hf,^(159)Tb,^(115)In,^(103)Rh,and ^(90)Zr,were performed and compared with the available experimental data in EXFOR,which suggest that further experiments are required for a series of photonuclear reaction channels.Flux-averaged cross sections and isomer ratios(IR)resulting from such bremsstrahlung sources are theoretically deduced.The results suggest that IR measurements can be used to constrain nuclear components,such asγstrength function and optical model potential.In addition,the detection of the decay characteristics was evaluated with Geant4 simulations.The use of the LWFA electron beam and its bremsstrahlung for photonuclear studies involving nuclear isomers is anticipated.展开更多
BACKGROUND Necrotizing enterocolitis(NEC)is a multifactorial disease that predominantly affects premature neonates.Intestinal dysbiosis plays a critical role in NEC pathogenesis in premature neonates.The main risk fac...BACKGROUND Necrotizing enterocolitis(NEC)is a multifactorial disease that predominantly affects premature neonates.Intestinal dysbiosis plays a critical role in NEC pathogenesis in premature neonates.The main risk factor for NEC in term infants is mesenteric hypoperfusion associated with ductaldependent congenital heart disease(CHD)that eventually leads to intestinal ischemia.The incidence of NEC in neonates with critical CHD is 6.8%-13%.However,the role of the intestinal microbiome in NEC pathogenesis in infants with ductal-dependent CHD remains unclear.CASE SUMMARY A male term neonate with right atrial isomerism underwent modified Blalock-Taussig shunt placement on the 14^(th)day of life and had persistent mesenteric hypoperfusion after surgery.The patient had episodes of NEC stageⅡA on the 1^(st)and 28^(th)days after cardiac surgery.Fecal microbial composition was analyzed before and after cardiac surgery by sequencing region V4 of the 16S rRNA gene.Before surgery,species belonging to genera Veillonella and Clostridia and class Gammaproteobacteria were detected,Bifidobacteriaceae showed a low abundance.The first NEC episode was associated with postoperative hemodynamic instability,intestinal ischemiareperfusion injury during cardiopulmonary bypass,and a high abundance of Clostridium paraputrificum(Clostridium sensu stricto I)(56.1%).Antibacterial therapy after the first NEC episode resulted in increased abundance of Gammaproteobacteria,decreased abundance of Firmicutes,and low alpha diversity.These changes in the microbial composition promoted the growth of Clostridium sensu strictoⅠ(72.0%)before the second NEC episode.CONCLUSION A high abundance of Clostridium sensu strictoⅠand mesenteric hypoperfusion may have contributed to NEC in the present case.展开更多
In-situ MgO-doped ordered mesoporous carbon(OMC@MgO)was fabricated by formaldehyde-free self-assembly method,in which biomass-derived tannin was used as carbon precursor replacing fossil-based phenolics,Mg^(2+)as both...In-situ MgO-doped ordered mesoporous carbon(OMC@MgO)was fabricated by formaldehyde-free self-assembly method,in which biomass-derived tannin was used as carbon precursor replacing fossil-based phenolics,Mg^(2+)as both cross-linker and precursor of catalytic sites.Up to~20 wt% MgO could be doped in the carbon skeleton with good dispersion retaining well-ordered mesoporous structures,while more MgO content(35 wt%)led to the failing in the formation of ordered mesoporous structure.The OMC@MgO possessed a high specific surface area(298.8 m^(2) g^(-1)),uniform pore size distribution(4.8 nm)and small crystallite size of MgO(1.73 nm)due to the confinement effect of ordered mesoporous structure.Using OMC@MgO as the heterogeneous catalyst,a maximum fructose yield of 32.4% with a selectivity up to 81.1%was achieved from glucose in water(90℃,60 min),which is much higher than that obtained using the MgO doped active carbon via conventional post-impregnation method(26.5%yield with 58.3% selectivity).Higher reaction temperature(>90℃)resulted in decrease of selectivity due to the formation of humins.The designed OMC@MgO displayed tolerant to high initial glucose concentrations(10 wt%)and could remain good recyclability without significant loss of activity for three cycles.展开更多
Sialylated N-glycan isomers withα2-3 orα2-6 linkage(s)have distinctive roles in glycoproteins,but are difficult to distinguish.Wild-type(WT)and glycoengineered(mutant)therapeutic glycoproteins,cytotoxic T lymphocyte...Sialylated N-glycan isomers withα2-3 orα2-6 linkage(s)have distinctive roles in glycoproteins,but are difficult to distinguish.Wild-type(WT)and glycoengineered(mutant)therapeutic glycoproteins,cytotoxic T lymphocyte-associated antigen-4-immunoglobulin(CTLA4-Ig),were produced in Chinese hamster ovary cell lines;however,their linkage isomers have not been reported.In this study,N-glycans of CTLA4-Igs were released,labeled with procainamide,and analyzed by liquid chromatography-tandem mass spectrometry(MS/MS)to identify and quantify sialylated N-glycan linkage isomers.The linkage isomers were distinguished by comparison of 1)intensity of the N-acetylglucosamine ion to the sialic acid ion(Ln/Nn)using different fragmentation stability in MS/MS spectra and 2)retention time-shift for a selective m/z value in the extracted ion chromatogram.Each isomer was distinctively identified,and each quantity(>0.1%)was obtained relative to the total N-glycans(100%)for all observed ionization states.Twenty sialylated N-glycan isomers with onlyα2-3 linkage(s)in WT were identified,and each isomer's sum of quantities was 50.4%.Furthermore,39 sialylated N-glycan isomers(58.8%)in mono-(3 N-glycans;0.9%),bi-(18;48.3%),tri-(14;8.9%),and tetra-(4;0.7%)antennary structures of mutant were obtained,which comprised mono-(15 N-glycans;25.4%),di-(15;28.4%),tri-(8;4.8%),and tetra-(1;0.2%)sialylation,respectively,with onlyα2-3(10 N-glycans;4.8%),bothα2-3 andα2-6(14;18.4%),and onlyα2-6(15;35.6%)linkage(s).These results are consistent with those forα2-3 neuraminidase-treated N-glycans.This study generated a novel plot of Ln/Nn versus retention time to distinguish sialylated N-glycan linkage isomers in glycoprotein.展开更多
The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)ha...The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)have been successfully prepared and investigated for n-pentane isomerization.The results showed that the core-shell Ni-SA@Z-30 provided a sustained high isopentane yield(63.1%)with little or no deactivation within 5000 min at a mild reaction pressure of 2.0 MPa,which can be attributed to the following factors:(i)carbon deposition was greatly suppressed by the large pore size and huge pore volume;(ii)the loss of sulfur entities was suppressed because the small and highly dispersed tetragonal ZrO_(2) particles can bond with the S species strongly;(iii)strong Brønsted acidity can be maintained well after the isomerization.The pore structures and acid nature of the core-shell Ni-SA@Z-x are entirely different from those of the normal structure Ni-S_(2)O_(8)^(2−)/ZrO_(2)-Al_(2)O_(3),even though the Al content and the compositions of the individual components are the same.The Al_(2)O_(3)cores endow the catalysts with high internal surface area and high mechanical strength.Meanwhile,the ZrO_(2) shell,which consists of more and smaller tetragonal ZrO_(2) particles because of the large surface area of the Al_(2)O_(3)core,promotes the formation of more stable sulfur species and stronger binding sites.展开更多
We present a quantum dynamics study on the isotope effects of hydro-gen transfer isomerization in the formic acid dimer,and this is achieved by multidimensional dy-namics calculations with an efficient quantum mechani...We present a quantum dynamics study on the isotope effects of hydro-gen transfer isomerization in the formic acid dimer,and this is achieved by multidimensional dy-namics calculations with an efficient quantum mechanical theoretical scheme developed by our group,on a full-dimensional neural network ab initio potential energy surface.The ground-state and fundamental tun-neling splittings for four deuterium isotopologues of formic acid dimer are considered,and the calculated results are in very good general agreement with the avail-able experimental measurements.Strong isotope effects are revealed,the mode-specific funda-mental excitation effects on the tunneling rate are evidently influenced by the deuterium sub-stitution of H atom with the substitution on the OH bond being more effective than on the CH bond.Our studies are helpful for acquiring a better understanding of isotope effects in the double-hydrogen transfer processes.展开更多
A series of Ferrierite(FER)zeolites were prepared via hydrothermal synthesis in the absence of organic templates with the aid of sodium-type FER zeolite(NaFER)or NaFER suspensions(NaFERsus)acquired by NaOH solution tr...A series of Ferrierite(FER)zeolites were prepared via hydrothermal synthesis in the absence of organic templates with the aid of sodium-type FER zeolite(NaFER)or NaFER suspensions(NaFERsus)acquired by NaOH solution treatment as seeds.The differences in the structures and acid sites of the obtained FER zeolite catalysts arising from the choice of seed were investigated,and the catalytic performances of the obtained FER zeolites were evaluated in the skeletal isomerization of n-butene.The results indicate that the samples synthesized using NaFERsus feature more Br?nsted acid sites(BAS)in the 10-membered-ring(10-MR)at the expense of strong acid and Lewis acid sites(LAS),compared with samples derived from NaFER.Therefore,the FER samples synthesized using NaFERsus outperformed the NaFER counterparts as the BAS in 10-MR and LAS were the main active sites,while BAS in 8-MR and LAS were responsible for side reactions,such as polymerization,cracking,and carbon deposition in n-butene isomerization.The optimized FER catalyst was continuously used for 720 h at 350℃ at 0.1 MPa under an n-butene space velocity of 2.0 h^(-1),during which the n-butene conversion remained at>40%,and the isobutylene yield was>37.5%.展开更多
采用离子动量成像谱仪研究了能量为1.0 ke V的电子束碰撞条件下CF_(4)分子的解离动力学.实验上,对解离离子的三维动量进行了成像测量,通过离子飞行时间关联谱识别了CF_(4)^(2+)异构化生成F_(2)^(+)分子的两个通道:F_(2)^(+)+CF_(2)^(+)...采用离子动量成像谱仪研究了能量为1.0 ke V的电子束碰撞条件下CF_(4)分子的解离动力学.实验上,对解离离子的三维动量进行了成像测量,通过离子飞行时间关联谱识别了CF_(4)^(2+)异构化生成F_(2)^(+)分子的两个通道:F_(2)^(+)+CF_(2)^(+)与CF^(+)+F_(2)^(+)+F,得到了两个通道的离子动能及动能释放分布.对于其中的三体解离通道,我们进一步采用Dalitz图与Newton图等三体动力学分析方法对解离碎片的动量关联进行了分析.该通道以两个带电离子的背对背出射为主,中性的F原子作为旁观者只得到极小的反冲动量.展开更多
轻烃异构化一般以C_(5)和C_(6)烃为原料,C_(7)及C_(7)以上烃类在异构化过程中由于存在较为剧烈的裂化反应,致使异构化油收率较低。作为一种新型低温轻烃异构化催化剂,离子液体对大分子烃类原料的适应性不佳。因此,在大分子烃类异构化过...轻烃异构化一般以C_(5)和C_(6)烃为原料,C_(7)及C_(7)以上烃类在异构化过程中由于存在较为剧烈的裂化反应,致使异构化油收率较低。作为一种新型低温轻烃异构化催化剂,离子液体对大分子烃类原料的适应性不佳。因此,在大分子烃类异构化过程中,抑制副反应、提高异构化油收率一直是研究的难点和重点。基于离子液体催化烷烃异构化反应机理,通过异丁烷循环抑制副反应、促进异构化反应的进行,进而降低异构化产物中C_(4)烷烃的含量,提高异构化油的收率。系统考察了异丁烷引入量、反应温度、反应时间、搅拌速率以及酸烃比等工艺条件对氯铝酸离子液体催化正庚烷异构化反应的影响规律。结果表明,体系中大量异丁烷的循环提高了氢转移速率,抑制了裂化、歧化等副反应,使副产物C 4组分的含量大幅降低。在异丁烷引入量为正庚烷体积的30%、反应温度为50℃、反应时间为1 h、搅拌速率为1500 r min和酸烃比(离子液体与正庚烷体积比)为1的条件下,正庚烷转化率达到91.0%,异构烷烃选择性和液体收率分别达到87.2%和93.5%;与未引入异丁烷体系相比,正庚烷转化率相近时,引入异丁烷体系的异构烷烃选择性和液体收率分别提高了16.0百分点和14.8百分点。展开更多
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.
基金Financial support by Dual Initiative Project of Jiangsu Province and Changzhou University is gratefully acknowledgedSample analysis supported by Analysis and Testing Center,NERC Biomass of Changzhou University was also greatly acknowledged.
文摘The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of drugs.Nowadays,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose isomerase.Some low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and HFCS.However,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare sugars.Considering the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial products.In this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.
文摘In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.
文摘The reaction of 7-amino-4-methyl-2(1H)-quinolone 1 and its 6-methyl derivative 2 with Vilsmeier reagent (DMF and POCl3) afforded 7-[1-aza-2-(dimethylamino)vinyl]-4-methyl-hydroquinolin-2-one 3 and 7-[1-aza-2-(dimethylamino)vinyl]-4,6-dimethylhydroquinolin- 2-one 4, respec-tively. H-1-NMR analysis in different solvents indicated that isomerism occurred due to hindered rotation around the (CH3)(2)N-C:N o -bond. The rotational energy barrier of 3 was calculated.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2014AM026)the Taishan Scholar Project of Shandong Province,China
文摘One-photon absorption and two-photon absorption(TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model.The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer(ICT)properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 10904085)
文摘The influence of rotational isomerism on the two-photon absorption (TPA) of FTC chromophores has been investi- gated using the quadratic response theory with the B3LYP functional. Eight rotamers induced by three rotatable single bonds in the molecule are fully optimized, and it is found that their conformational energies are nearly degenerate. Our calculations demonstrate that rotational isomerism has an important effect on the TPA cross sections. For a certain rotamer, the maximum TPA cross section is enhanced significantly. In addition, in the longer wavelength region, the rotational isomerism could lead to a large shift of the TPA position.
基金supported by the National Natural Science Foundation of China (Nos.11921006,U2230133)Beijing Outstanding Young Scientists Program+2 种基金National Grand Instrument Project (No.2019YFF01014400)National Key R&D Program of China (No.2022YFA1603303)Open Foundation of Key Laboratory of High Power Laser and Physics,Chinese Academy of Sciences (No.SGKF202104)。
文摘In this study,we theoretically investigate the feasibility of using laser-wakefield accelerated(LWFA)electrons for the photonuclear measurement of nuclear isomers according to the characteristics of the electrons obtained from LWFA experiments conducted at the Compact Laser-Plasma Accelerator(CLAPA)laboratory.The experiments at the CLAPA show that a stable electron beam with an energy of 78-135 MeV and a charge of 300-600 pC can be obtained.The bremsstrahlung spectra were simulated using Geant4,which suggests that a bremsstrahlung source with a peak intensity of 10^(19) photons/s can be generated.Theoretical calculations of isomer production cross sections from the photonuclear reactions on six target nuclei,^(197)Au,^(180)Hf,^(159)Tb,^(115)In,^(103)Rh,and ^(90)Zr,were performed and compared with the available experimental data in EXFOR,which suggest that further experiments are required for a series of photonuclear reaction channels.Flux-averaged cross sections and isomer ratios(IR)resulting from such bremsstrahlung sources are theoretically deduced.The results suggest that IR measurements can be used to constrain nuclear components,such asγstrength function and optical model potential.In addition,the detection of the decay characteristics was evaluated with Geant4 simulations.The use of the LWFA electron beam and its bremsstrahlung for photonuclear studies involving nuclear isomers is anticipated.
基金Supported by the Russian Science Foundation,No.22-25-00484。
文摘BACKGROUND Necrotizing enterocolitis(NEC)is a multifactorial disease that predominantly affects premature neonates.Intestinal dysbiosis plays a critical role in NEC pathogenesis in premature neonates.The main risk factor for NEC in term infants is mesenteric hypoperfusion associated with ductaldependent congenital heart disease(CHD)that eventually leads to intestinal ischemia.The incidence of NEC in neonates with critical CHD is 6.8%-13%.However,the role of the intestinal microbiome in NEC pathogenesis in infants with ductal-dependent CHD remains unclear.CASE SUMMARY A male term neonate with right atrial isomerism underwent modified Blalock-Taussig shunt placement on the 14^(th)day of life and had persistent mesenteric hypoperfusion after surgery.The patient had episodes of NEC stageⅡA on the 1^(st)and 28^(th)days after cardiac surgery.Fecal microbial composition was analyzed before and after cardiac surgery by sequencing region V4 of the 16S rRNA gene.Before surgery,species belonging to genera Veillonella and Clostridia and class Gammaproteobacteria were detected,Bifidobacteriaceae showed a low abundance.The first NEC episode was associated with postoperative hemodynamic instability,intestinal ischemiareperfusion injury during cardiopulmonary bypass,and a high abundance of Clostridium paraputrificum(Clostridium sensu stricto I)(56.1%).Antibacterial therapy after the first NEC episode resulted in increased abundance of Gammaproteobacteria,decreased abundance of Firmicutes,and low alpha diversity.These changes in the microbial composition promoted the growth of Clostridium sensu strictoⅠ(72.0%)before the second NEC episode.CONCLUSION A high abundance of Clostridium sensu strictoⅠand mesenteric hypoperfusion may have contributed to NEC in the present case.
基金supported by the Natural Science Fund for Distinguished Young Scholars of Tianjin (17JCJQJC45500)the National Natural Science Foundation of China (NSFC,21876091 and 22178181)Tianjin Municipal Science and Technology Project (18PTZWHZ00150).
文摘In-situ MgO-doped ordered mesoporous carbon(OMC@MgO)was fabricated by formaldehyde-free self-assembly method,in which biomass-derived tannin was used as carbon precursor replacing fossil-based phenolics,Mg^(2+)as both cross-linker and precursor of catalytic sites.Up to~20 wt% MgO could be doped in the carbon skeleton with good dispersion retaining well-ordered mesoporous structures,while more MgO content(35 wt%)led to the failing in the formation of ordered mesoporous structure.The OMC@MgO possessed a high specific surface area(298.8 m^(2) g^(-1)),uniform pore size distribution(4.8 nm)and small crystallite size of MgO(1.73 nm)due to the confinement effect of ordered mesoporous structure.Using OMC@MgO as the heterogeneous catalyst,a maximum fructose yield of 32.4% with a selectivity up to 81.1%was achieved from glucose in water(90℃,60 min),which is much higher than that obtained using the MgO doped active carbon via conventional post-impregnation method(26.5%yield with 58.3% selectivity).Higher reaction temperature(>90℃)resulted in decrease of selectivity due to the formation of humins.The designed OMC@MgO displayed tolerant to high initial glucose concentrations(10 wt%)and could remain good recyclability without significant loss of activity for three cycles.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)and funded by the Ministry of Education,Korea(Grant No.:2021R1A6A1A03044296)This study was supported by the Chung-Ang University Graduate Research Scholarship in 2022.
文摘Sialylated N-glycan isomers withα2-3 orα2-6 linkage(s)have distinctive roles in glycoproteins,but are difficult to distinguish.Wild-type(WT)and glycoengineered(mutant)therapeutic glycoproteins,cytotoxic T lymphocyte-associated antigen-4-immunoglobulin(CTLA4-Ig),were produced in Chinese hamster ovary cell lines;however,their linkage isomers have not been reported.In this study,N-glycans of CTLA4-Igs were released,labeled with procainamide,and analyzed by liquid chromatography-tandem mass spectrometry(MS/MS)to identify and quantify sialylated N-glycan linkage isomers.The linkage isomers were distinguished by comparison of 1)intensity of the N-acetylglucosamine ion to the sialic acid ion(Ln/Nn)using different fragmentation stability in MS/MS spectra and 2)retention time-shift for a selective m/z value in the extracted ion chromatogram.Each isomer was distinctively identified,and each quantity(>0.1%)was obtained relative to the total N-glycans(100%)for all observed ionization states.Twenty sialylated N-glycan isomers with onlyα2-3 linkage(s)in WT were identified,and each isomer's sum of quantities was 50.4%.Furthermore,39 sialylated N-glycan isomers(58.8%)in mono-(3 N-glycans;0.9%),bi-(18;48.3%),tri-(14;8.9%),and tetra-(4;0.7%)antennary structures of mutant were obtained,which comprised mono-(15 N-glycans;25.4%),di-(15;28.4%),tri-(8;4.8%),and tetra-(1;0.2%)sialylation,respectively,with onlyα2-3(10 N-glycans;4.8%),bothα2-3 andα2-6(14;18.4%),and onlyα2-6(15;35.6%)linkage(s).These results are consistent with those forα2-3 neuraminidase-treated N-glycans.This study generated a novel plot of Ln/Nn versus retention time to distinguish sialylated N-glycan linkage isomers in glycoprotein.
文摘The non-noble metal modified sulfated zirconia was found easy to deactivate.Herein,highly active and highly stable non-noble core-shell Ni-S_(2)O_(8)^(2−)/Al_(2)O_(3)@ZrO_(2) catalysts(Ni-SA@Z-x,x=Al content in wt%)have been successfully prepared and investigated for n-pentane isomerization.The results showed that the core-shell Ni-SA@Z-30 provided a sustained high isopentane yield(63.1%)with little or no deactivation within 5000 min at a mild reaction pressure of 2.0 MPa,which can be attributed to the following factors:(i)carbon deposition was greatly suppressed by the large pore size and huge pore volume;(ii)the loss of sulfur entities was suppressed because the small and highly dispersed tetragonal ZrO_(2) particles can bond with the S species strongly;(iii)strong Brønsted acidity can be maintained well after the isomerization.The pore structures and acid nature of the core-shell Ni-SA@Z-x are entirely different from those of the normal structure Ni-S_(2)O_(8)^(2−)/ZrO_(2)-Al_(2)O_(3),even though the Al content and the compositions of the individual components are the same.The Al_(2)O_(3)cores endow the catalysts with high internal surface area and high mechanical strength.Meanwhile,the ZrO_(2) shell,which consists of more and smaller tetragonal ZrO_(2) particles because of the large surface area of the Al_(2)O_(3)core,promotes the formation of more stable sulfur species and stronger binding sites.
基金supported by the National Natural Sci-ence Foundation of China(No.21973098 and No.22133003)the Beijing National Laboratory for Molecular SciencesJianwei Cao acknowledges the Youth Innovation Promotion Association CAS(No.2018045).
文摘We present a quantum dynamics study on the isotope effects of hydro-gen transfer isomerization in the formic acid dimer,and this is achieved by multidimensional dy-namics calculations with an efficient quantum mechanical theoretical scheme developed by our group,on a full-dimensional neural network ab initio potential energy surface.The ground-state and fundamental tun-neling splittings for four deuterium isotopologues of formic acid dimer are considered,and the calculated results are in very good general agreement with the avail-able experimental measurements.Strong isotope effects are revealed,the mode-specific funda-mental excitation effects on the tunneling rate are evidently influenced by the deuterium sub-stitution of H atom with the substitution on the OH bond being more effective than on the CH bond.Our studies are helpful for acquiring a better understanding of isotope effects in the double-hydrogen transfer processes.
基金the funding of the project by the CNPC Corporation (2018B-1907)。
文摘A series of Ferrierite(FER)zeolites were prepared via hydrothermal synthesis in the absence of organic templates with the aid of sodium-type FER zeolite(NaFER)or NaFER suspensions(NaFERsus)acquired by NaOH solution treatment as seeds.The differences in the structures and acid sites of the obtained FER zeolite catalysts arising from the choice of seed were investigated,and the catalytic performances of the obtained FER zeolites were evaluated in the skeletal isomerization of n-butene.The results indicate that the samples synthesized using NaFERsus feature more Br?nsted acid sites(BAS)in the 10-membered-ring(10-MR)at the expense of strong acid and Lewis acid sites(LAS),compared with samples derived from NaFER.Therefore,the FER samples synthesized using NaFERsus outperformed the NaFER counterparts as the BAS in 10-MR and LAS were the main active sites,while BAS in 8-MR and LAS were responsible for side reactions,such as polymerization,cracking,and carbon deposition in n-butene isomerization.The optimized FER catalyst was continuously used for 720 h at 350℃ at 0.1 MPa under an n-butene space velocity of 2.0 h^(-1),during which the n-butene conversion remained at>40%,and the isobutylene yield was>37.5%.
文摘采用离子动量成像谱仪研究了能量为1.0 ke V的电子束碰撞条件下CF_(4)分子的解离动力学.实验上,对解离离子的三维动量进行了成像测量,通过离子飞行时间关联谱识别了CF_(4)^(2+)异构化生成F_(2)^(+)分子的两个通道:F_(2)^(+)+CF_(2)^(+)与CF^(+)+F_(2)^(+)+F,得到了两个通道的离子动能及动能释放分布.对于其中的三体解离通道,我们进一步采用Dalitz图与Newton图等三体动力学分析方法对解离碎片的动量关联进行了分析.该通道以两个带电离子的背对背出射为主,中性的F原子作为旁观者只得到极小的反冲动量.
文摘轻烃异构化一般以C_(5)和C_(6)烃为原料,C_(7)及C_(7)以上烃类在异构化过程中由于存在较为剧烈的裂化反应,致使异构化油收率较低。作为一种新型低温轻烃异构化催化剂,离子液体对大分子烃类原料的适应性不佳。因此,在大分子烃类异构化过程中,抑制副反应、提高异构化油收率一直是研究的难点和重点。基于离子液体催化烷烃异构化反应机理,通过异丁烷循环抑制副反应、促进异构化反应的进行,进而降低异构化产物中C_(4)烷烃的含量,提高异构化油的收率。系统考察了异丁烷引入量、反应温度、反应时间、搅拌速率以及酸烃比等工艺条件对氯铝酸离子液体催化正庚烷异构化反应的影响规律。结果表明,体系中大量异丁烷的循环提高了氢转移速率,抑制了裂化、歧化等副反应,使副产物C 4组分的含量大幅降低。在异丁烷引入量为正庚烷体积的30%、反应温度为50℃、反应时间为1 h、搅拌速率为1500 r min和酸烃比(离子液体与正庚烷体积比)为1的条件下,正庚烷转化率达到91.0%,异构烷烃选择性和液体收率分别达到87.2%和93.5%;与未引入异丁烷体系相比,正庚烷转化率相近时,引入异丁烷体系的异构烷烃选择性和液体收率分别提高了16.0百分点和14.8百分点。