Structural Isomers:Small Change with Big Difference in Anion Storage

Organic electrode materials are promising for batteries.However,the reported organic electrodes are often facing the challenges of low specific capacity,low voltage,poor rate capability and vague charge storage mechanisms,etc.Isomers are good platform to investigate the charge storage mechanisms and enhance the performance of batteries,which,however,have not been focused in batteries.Herein,two isomers are reported for batteries.As a result,the isomer tetrathiafulvalene(TTF)could store two monovalent anions reversibly,deriving an average discharge voltage of 1.05 V and a specific capacity of 220 mAh g−1 at a current density of 2 C.On the other hand,the other isomer tetrathianaphthalene could only reversibly store one monovalent anion and upon further oxidation,it would undergo an irreversible solid-state molecular rearrangement to TTF.The molecular rearrangement was confirmed by electrochemical performances,X-ray diffraction patterns,nuclear magnetic resonance spectra,and 1H detected heteronuclear multiple bond correlation spectra.These results suggested the small structural change could lead to a big difference in anion storage,and we hope this work will stimulate more attention to the structural design for boosting the performance of organic batteries.

Simulation of nuclear isomer production in laser-induced plasma

Nuclear isomers play essential roles in various fields,including stellar nucleosynthesis,nuclear clocks,nuclear batteries,clean nuclear energy,and-ray lasers.Recent technological advances in high-intensity lasers have made it possible to excite or de-excite nuclear isomers using table-top laser equipment.Utilizing a particle-in-cell code,we investigate the interaction of a laser with a nanowire array and calculate the production rates of the^(73m)Ge(E_(1)=13.3 keV)and^(107m)Ag(E_(1)=93.1 keV)isomers.For^(73m1)Ge,production by Coulomb excitation is found to contribute a peak efficiency of 1.0×10^(19) particles s^(−1)J^(−1),while nuclear excitation by electron capture(NEEC)contributes a peak of 1.65×10^(11)particles s^(−1)J^(−1).These results indicate a high isomeric production ratio,as well as demonstrating the potential for confirming the existence of NEEC,a long-expected but so far experimentally unobserved fundamental process.

Isomeric fluorescence sensors for wide range detection of ionizing radiations

In order to achieve a wider range of ionizing radiations detection,novel fluorescence sensing materials have been developed that utilize the fluorescence enhancement phenomenon caused by the intramolecular photoinduced electron transfer(PET)effect.Two perylene diimide isomers PDI-P and PDI-B were designed and synthesized,and their molecular structures were characterized by high-resolution Fourier transform mass spectrometry(HRMS),nuclear magnetic resonance hydrogen and carbon spectroscopy(~1H and~(13)C NMR).The interaction between ionizing radiation and fluorescent molecules was simulated by HCl titration.The results show that combining PDIs and HCl can improve fluorescence through the retro-PET process.Despite the similarities in chemical structures,the fluorescent enhancement multiple of PDI-B with aromatic amine as electron donor is much higher than that of PDI-P with alkyl amine.In the direct irradiation experiments of ionizing radiation,the emission enhancement multiples of PDI-P and PDI-B are 2.01 and 45.4,respectively.Furthermore,density functional theory(DFT)and time-dependent density functional theory(TDDFT)calculations indicate that the HOMO and HOMO-1 energy ranges of PDI-P and PDI-B are 0.54 e V and 1.13 e V,respectively.A wider energy range has a stronger driving force on electrons,which is conducive to fluorescence quenching.Both femtosecond transient absorption spectroscopy(fs-TAS)and transient fluorescence spectroscopy(TFS)tests show that PDI-B has shorter charge separation lifetime and higher electron transfer rate constant.Although both isomers can significantly reduce LOD during PET process,PDI-B with aromatic amine has a wider detection range of 0.118—240 Gy due to its larger emission enhancement,which is a leap of three orders of magnitude.It breaks through the detection range of gamma radiation reported in existing studies,and provides theoretical support for the further study of sensitive and effective new materials for ionizing radiation detection.

Photonuclear production of nuclear isomers using bremsstrahlung induced by laser-wakefield electrons

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.

Fragmentation stability and retention time-shift obtained by LC-MS/MS to distinguish sialylated N-glycan linkage isomers in therapeutic glycoproteins

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.

Synthesis of ZSM-22/SAPO-11 composite molecular sieve-based catalysts with small crystallites and superior n-alkane hydroisomerization performance

To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).

Research on the Relationship between Three Isomers of Microcystins and Environmental Factors

[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.

Experimental and kinetic study of n-heptane isomerization on nanoporous Pt-(Re,Sn)/HZSM5-HMS catalysts

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 ℃.

Synthesis of hierarchical SAPO-11-based catalysts with Al-based metal-organic framework derivative as mesoporogen to improve n-decane branched isomerization

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.

EFFECT OF NITRATE AND PHOSPHATE ON ACCUMULATION OF β-CAROTENE ISOMERS IN DUNALIELLA SALINA

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 KNO3and 0.1 mmol/L KH2, PO4 are favourable for accumulation of total cis β-carotene.

n-Nonane hydroisomerization over hierarchical SAPO-11-based catalysts with sodium dodecylbenzene sulfonate as a dispersant

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.

Two Novel Isomers of HPS3 System

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.

Theoretical investigation on isomer formation probability and free energy of small C clusters

Molecular dynamics simulations and free energy calculations are employed to investigate the evolution, formation probability, detailed balance, and isomerization rate of small C cluster isomer at 2500 K. For C10, the isomer formation probability predicted by free energy is in good agreement with molecular dynamics simulation. However, for C20, C3o, and C36, the formation probabilities predicted by free energy are not in agreement with molecular dynamics simulations. Although the cluster systems are in equilibrium, detailed balance is not reached. Such results may be attributed to high transformation barriers between cage, bowl, and sheet isomers. In summary, for mesoscopic nanosystems the free energy criterion, which commonly holds for macroscopic systems in dynamic equilibrium, may not provide a good prediction for isomer formation probability. New theoretical criterion should be further investigated for predicting the isomer formation probability of a mesoscopic nanosystem.

Aromatic Character of All Possible C_(36)H_2 Isomers

The stability of C36H2 isomers and selection rules for choosing position in addition reactions based on symmetrical C36（D6h and D2d） fullerene have been studied by means of Aihara＇s topological resonance energy （TRE） and bond resonance energy （BRE） methods. The relation between the addition pattern and BREs is established, showing high antiaromatic bonds are preferred for addition. These results show that TRE and BRE methods can be used to predict and interpret addition sites for these systems.

Serum Mac-2 binding protein glycosylation isomer level predicts hepatocellular carcinoma development in E-negative chronic hepatitis B patients

BACKGROUND Liver cirrhosis is a major risk factor for hepatocellular carcinoma(HCC)development in chronic hepatitis B(CHB). Serum Mac-2 binding protein glycosylation isomer(M2 BPGi) is a novel serological marker for fibrosis. The role of M2 BPGi in prediction of HCC is unknown.AIM To examine the role of serum M2 BPGi in predicting HCC development in hepatitis B e antigen(HBeAg)-negative patients.METHODS Treatment-naive CHB patients with documented spontaneous HBeAg seroconversion were recruited. Serum M2 BPGi was measured at baseline(within3 years from HBeAg seroconversion), at 5 years and 10 years after HBeAg seroconversion and expressed as cut-off index(COI). Multivariate cox regression was performed to identify predictors for HCC development. ROC analysis was used to determine the cut-off value of M2 BPGi.RESULTS Among 207 patients(57% male, median age at HBeAg seroconversion 40 years old) with median follow-up of 13.1(11.8-15.5) years, the cumulative incidence of HCC at 15 years was 7%. Median M2 BPGi levels were significantly higher in patients with HCC compared to those without HCC(baseline: 1.39 COI vs 0.38 COI, P < 0.001; 5-year: 1.45 COI vs 0.47 COI, P < 0.001; 10-year: 1.20 COI vs 0.55 COI, P = 0.001). Multivariate analysis revealed age at HBeAg seroconversion[odds ratio(OR) = 1.196, 95% confidence interval(CI): 1.034-1.382, P = 0.016] and baseline M2 BPGi(OR = 4.666, 95%CI: 1.296-16.802, P = 0.018) were significant factors predictive of HCC. Using a cut-off value of 0.68 COI, baseline M2 BPGi yielded AUROC of 0.883 with 91.7% sensitivity and 80.8% specificity.CONCLUSION High serum M2 BPGi within 3 years after HBeAg seroconversion was a strong predictor for subsequent HCC development in treatment-naive HBeAg-negative CHB patients.

Differentiation of Positional Isomers of Propyl Alcohols Using Filament-Induced Fluorescence

We experimentally demonstrate the recognition of positional isomers of propyl alcohol vapor through nonlinear fluorescence induced by high-intensity femtosecond laser filaments in air. By measuring characteristic fluorescence of n-propyl and isopropyl alcohol vapors produced by femtosecond filament excitation, it is found that they show identical spectra, that is, those from molecular bands of CH, C2, Nit, OH and CN, while the relative intensities are different. By comparing the ratios of the CH and C2 signals, the two propyl alcohol isomers are differentiated. The different signal intensities are ascribed to different ionization potentials of the two isomer molecules, leading to different production efficiencies of fluorescing fragments.

Theoretical Studies on Stabilities of C_(26)BN Isomers

The possible stable structures of substituted fullerene C26BN formed on the initial C28 cage with Td symmetry have been systematically studied on UHF/3-21g level with constrained symmetry(Cs or C1), the charge and multiplicity of all the isomers are zero and five, respectively. The geometry optimization and the vibrational frequencies analysis were performed on the same level with constrained symmetry(Cs or C1). The results show that the most stable isomer of C26BN is formed by boron and nitrogen atoms doping at 5,2-sites.

Global characterization of modifications to the charge isomers of IgG antibody

Posttranslational modifications of antibody products affect their stability,charge distribution,and drug activity and are thus a critical quality attribute.The comprehensive mapping of antibody modifications and different charge isomers(CIs)is of utmost importance,but is challenging.We intended to quantitatively characterize the posttranslational modification status of CIs of antibody drugs and explore the impact of posttranslational modifications on charge heterogeneity.The CIs of antibodies were fractionated by strong cation exchange chromatography and verified by capillary isoelectric focusing-whole column imaging detection,followed by stepwise structural characterization at three levels.First,the differences between CIs were explored at the intact protein level using a top-down mass spectrometry approach;this showed differences in glycoforms and deamidation status.Second,at the peptide level,common modifications of oxidation,deamidation,and glycosylation were identified.Peptide mapping showed nonuniform deamidation and glycoform distribution among CIs.In total,10 N-glycoforms were detected by peptide mapping.Finally,an in-depth analysis of glycan variants of CIs was performed through the detection of enriched glycopeptides.Qualitative and quantitative analyses demonstrated the dynamics of 24 N-glycoforms.The results revealed that sialic acid modification is a critical factor accounting for charge heterogeneity,which is otherwise missed in peptide mapping and intact molecular weight analyses.This study demonstrated the importance of the comprehensive analyses of antibody CIs and provides a reference method for the quality control of biopharmaceutical analysis.

Experimental investigation on combustion and unregulated emission characteristics of butanol-isomer/gasoline blends

Effects of butanol isomers on characteristics of combustion and emission were studied on PFI SI engine. Experiments were operated under the condition of 3 and 5 bar brake mean effective pressure (BMEP) engine loads and different equivalence ratios (φ=0.83-1.25) with engine speed of 1200 r/min using blends made of 70 vol.% gasoline and 30 vol.% butanol isomers (N30, S30, I30 and T30). The results indicated that compared with gasoline, all butanol isomer blends have higher cylinder pressure. N30 has the highest and most advanced peak pressure, and T30 shows a higher brake specific fuel consumption (BSFC) and lower brake thermal efficiency (BTE). N30 presents a lower UHC emissions and I30 has slightly higher CO emissions than other blends. For unregulated emissions, compared with gasoline, butanol isomer blends have higher acetaldehyde, and N30 produces a higher emission of 1,3-butadiene than other blends. A reduction in benzene, toluene, ethylbenzene and xylene (BTEX) has been found with butanol isomer blends.

Ohmefentanyl stereoisomers induce changes of CREB phosphorylation in hippocampus of mice in conditioned place preference paradigm

The present study was designed to determine the changes of phosphorylation of cAMP- response ele-ment binding protein (CREB) in hippocampus induced by ohmefentanyl stereoisomers (F9202 and F9204)in conditioned place preference (CPP) paradigm. The results showed that mice receiving F9202 and F9204displayed obvious CPP. They could all significantly stimulate CREB phosphorylation and maintained for along time without affecting total CREB protein levels. The effect of F9204 was similar to morphine whicheffect was more potent and longer than F9202. We also examined the effects of ketamine, a noncompetitiveN-mthyl-D-aspartate receptor (NR) antagonist, on morphine-, F9202- and F9204- induced CPP and phos-phorylation of CREB in hippocampus. Ketamine could suppress not only the place preference but also thephosphorylation of CREB produced by morphine, F9202 and F9204. These findings suggest that alterationsin the phosphorylation of CREB be relevant to opiates signaling and the development of opiates dependence.NR antagonists may interfere with opiates dependence and may have potential therapeutic implications.