Oxygen-vacancy-rich MnO_(x)supported RuO_(x)for efficient base-free oxidation of 5-hydroxymethylfurfural and 5-methoxymethylfurfural to 2,5-furandicarboxylic acid

2,5-Furandicarboxylic acid(FDCA)is a promising biomass-derived polymeric monomer that serves as an attractive alternative to terephthalic acid derived from fossil resources.However,the green and efficient production of FDCA through the oxidation of 5-hydroxymethylfurfural(HMF)and its derivatives is still rudimentary under base-free conditions.In this work,oxygen-vacancy-rich Mn Oxwas prepared and displayed a strong adsorption and anchoring ability to Ru species that mainly exposed the(210)plane of RuO_(2),bringing about highly dispersed and active interfacial Ru-O-Mn structures.Experimental results and density functional theory calculations confirm that these above features greatly facilitate the adsorption/activation of oxygen and the dehydrogenation-oxidation of HMF/5-methoxymethylfurfural(MMF),which enables an efficient FDCA production under base-free and mild conditions.Notably,a desirable FDCA yield of 86.56%was still obtained from concentrated HMF(10 wt%)under base-free conditions over oxygen-vacancy-rich Mn Oxsupported Ru Ox(1.0 MPaO_(2),120℃,6 h).This work delineates a facile catalyst preparation strategy for HMF/MMF oxidation,and might open a new avenue for the green synthesis of FDCA under base-free conditions.

Transforming liquid flow fuel cells to controllable reactors for highlyefficient oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid at low temperature

Highly-efficient oxidation of 5-hydroxymethylfurtural(HMF) to 2,5-furandicarboxylic acid(FDCA) at low temperature with air as the oxidant is still challenging.Herein,inspired by the respirato ry electron transport chain(ETC) of living cells mediated by electron carriers,we constructed artificial ETCs and transformed liquid flow fuel cells(LFFCs) to flexible reactors for efficient oxidation of HMF to produce FDCA under mild conditions.This LFFC reactor employed an electrodeposition modified nickel foam as an anode to promote HMF oxidation and(VO_(2))_(2)SO_(4) as a cathode electron carrier to facilitate the electron transfer to air.The reaction rate could be easily controlled by selecting the anode catalyst,adjusting the external loading and changing the cathodic electron carrier or oxidants.A maximal power density of 44.9 mW cm^(-2) at room temperature was achieved,while for FDCA production,short-circuit condition was preferred to achieve quick transfer of electrons.For a single batch operation with 0.1 M initial HMF,FDCA yield reached 97.1%.By fed-batch operation,FDCA concentration reached 144.5 g L^(-1) with a total yield of 96%.Ni^(2+)/Ni^(3+) redox couple was the active species mediating the electron transfer,while both experimental and DFT calculation results indicated that HMFCA pathway was the preferred reaction mechanism.

2型糖尿病伴干眼症病人血清和泪液分泌型卷曲相关蛋白5、脂肪酸结合蛋白4水平与病情严重程度的相关性

目的分析分泌型卷曲相关蛋白5(SFRP-5)、脂肪酸结合蛋白4(FABP4)在2型糖尿病(T2DM)伴干眼症病人血清和泪液中的表达及其与病情严重程度的相关性。方法选取2020年12月至2021年12月唐山市眼科医院收治的T2DM病人145例,其中单纯T2DM病人84例168眼(T2DM组),伴干眼症病人61例122眼(T2DM伴干眼症组),另选取同期该院体检健康者50例100眼作为对照组。T2DM伴干眼症病人又分为轻度组(29例)、中度组(17例)、重度组(15例)。利用酶联免疫吸附法测定所有受试者血清和泪液中SFRP-5、FABP4水平;相关性分析采用Pearson法或Spearman法;logistic回归分析影响T2DM病人干眼症发生的因素。结果T2DM伴干眼症组、T2DM组血清和泪液SFRP-5水平均低于对照组(106.09±8.37、135.72±9.26比158.34±9.45,28.85±5.13、58.27±6.14比45.18±5.92),T2DM伴干眼症组低于T2DM组(P<0.05);T2DM伴干眼症组、T2DM组血清和泪液FABP4水平均高于对照组(70.63±6.59、58.27±6.14比45.18±5.92,15.91±3.76、10.28±3.58比7.72±3.29),T2DM伴干眼症组高于T2DM组(P<0.05)。重度组、中度组血清和泪液SFRP-5水平(68.29±7.15、95.54±8.34比131.82±9.02,12.83±4.62、24.72±5.49比39.56±5.18)、泪膜破裂时间(BUT)、泪液分泌试验(SIT)低于轻度组,重度组低于中度组(P<0.05);重度组、中度组血清和泪液FABP4水平(84.56±6.83、73.18±6.94比61.93±6.27,25.64±4.19、17.15±3.86比10.16±3.47)及眼表疾病指数量表(OSDI)积分高于轻度组,重度组高于中度组(P<0.05)。T2DM伴干眼症病人血清与泪液SFRP-5水平呈正相关,血清与泪液FABP4水平也呈正相关(P<0.05)。T2DM伴干眼症病人血清和泪液SFRP-5水平与OSDI积分均呈负相关,与BUT、SIT均呈正相关(P<0.05);血清和泪液FABP4水平与OSDI积分均呈正相关,与BUT、SIT均呈负相关(P<0.05)。血清和泪液SFRP-5水平是影响T2DM病人干眼症发生的独立保护因素,而血清和泪液FABP4水平是独立危险因素(P<0.05)。结论SFRP-5在T2DM伴干眼症病人血清和泪液中均低表达,FABP4均高表达,二者与病情严重程度密切相关。

All-trans retinoic acid regulates the expression of MMP-2 and TGF-β2 via RDH5 in retinal pigment epithelium cells

·AIM: To investigate the effect of all-trans retinoic acid(ATRA) on retinol dehydrogenase 5(RDH5), matrix metalloproteinase-2(MMP-2) and transforming growth factor-β2(TGF-β2) transcription levels, and the effect of RDH5 on MMP-2 and TGF-β2 in retinal pigment epithelium(RPE) cells.·METHODS: After adult RPE cell line-19(ARPE-19 cells) intervened with gradient concentrations of ATRA(0-20 μmol/L) for 24h, flow cytometry was used to detect the proliferation and apoptosis of cells in each group, and quantitative realtime polymerase chain reaction(q RT-PCR) was used to detect RDH5, MMP-2 and TGF-β2 m RNA expression. Then, after ARPE-19 cells transfected with three different si RNA targets for 48h, the RDH5 knockdown efficiency of each group and expression of MMP-2 and TGF-β2 m RNA within them was detected by q RT-PCR. ·RESULTS: Flow cytometry results showed that ATRA could inhibit the proliferation of RPE cells and promote the apoptosis of RPE cells, and the difference of apoptosis was statistically significant when the ATRA concentration exceeded 5 μmol/L and compared with the normal control group(P=0.027 and P=0.031, respectively). q RT-PCR results showed that ATRA could significantly inhibit the expression level of RDH5 m RNA(P<0.001) and promote the expression of MMP-2 and TGF-β2 m RNA(P=0.03 and P<0.001, respectively) in a dose-dependent manner, especially when treated with 5 μmol/L ATRA. The knockdown efficiency of RDH5 si RNA varies with different targets, among which RDH5 si RNA-435 had the highest knockdown efficiency, i.e., more than 50% lower than that of the negative control group(P=0.02). When RDH5 was knocked down for 48h, the results of q RT-PCR showed that the expressions of MMP-2 and TGF-β2 m RNA were significantly up-regulated(P<0.001).·CONCLUSION: ATRA inhibits the expression of RDH5 and promotes MMP-2 and TGF-β2, and further RDH5 knockdown significantly upregulates MMP-2 and TGF-β2. These findings suggest that RDH5 may be involved in an epithelial-mesenchymal transition of RPE cells mediated by ATRA.

Ti/PbO_(2)电极与Ti/IrO_(2)+Ta_(2)O_(5)电极催化体系降解酸性大红染料废水的比较研究

为比较Ti/PbO_(2)电极和Ti/IrO_(2)+Ta_(2)O_(5)电极催化体系降解酸性大红(GR)染料废水的处理效果,并确定体系最佳工艺参数。分别对Ti/PbO_(2)电极和Ti/IrO_(2)+Ta_(2)O_(5)电极催化体系内初始pH、染料初始浓度、电流密度、电解质浓度对GR染料降解率的影响进行了探索,比较工艺参数优化后两催化体系的GR降解率、电极形貌及TOC去除率。结果表明,工艺参数优化后(初始pH 6.38,染料初始浓度100 mg/L,电流密度50 mA/cm^(2),电解质浓度0.1 mg/L),Ti/PbO_(2)电极和Ti/IrO_(2)+Ta_(2)O_(5)电极催化体系GR去除率分别可达98.3%和61.1%,TOC去除率为25.4%和13.5%;结合电极表面形貌分析,Ti/IrO_(2)+Ta_(2)O_(5)电极表面损毁较明显,而Ti/PbO_(2)电极表面变化不大。因此,Ti/PbO_(2)电极催化体系GR降解率、TOC去除率均较高,且电极稳定性较好。研究结果为进一步推动电催化法在染料废水处理实际应用领域提供了理论参考。

乳酸浸出中低品位磷块岩富集P_(2)O_(5)的新工艺研究

贵州织金中低品位含稀土型磷矿石中P_(2)O_(5)的质量分数为15.47%,其主要矿物成分为氟磷灰石、胶磷矿、白云石、石英等属难选磷矿石。采用传统的选矿方法不能对该类磷矿石中的有用矿物与脉石矿物进行有效分离,为解决这一难题,利用相对分子质量较低的乳酸作为浸出剂对矿石中的碳酸盐组分进行选择性溶解,其中有用组分磷灰石因不溶于乳酸而得以保留,过滤除去滤液后,达到富集P_(2)O_(5)的目的。系统考察了乳酸质量分数、反应时间、反应温度、液固质量比、矿石粒度等因素对P_(2)O_(5)富集效果的影响。结果表明,在乳酸质量分数为9%、反应温度为50℃、反应时间为3 h、液固比(体积质量比,m L/g)为30∶1、矿石粒度为0.075~<0.09 mm的条件下,获得的磷精矿中P_(2)O_(5)质量分数为33.99%,达到了市场要求的磷矿石品位。利用乳酸选择性浸出磷矿石中碳酸盐脉石组分从而富集P_(2)O_(5)的工艺,具有富集率高、工艺简便、经济节能等特点,可有效提高含稀土磷矿资源的综合利用率,具有良好的推广应用前景。

中间体2-氯-4-氟-5-硝基苯甲酸的新合成方法

探索中间体2-氯-4-氟-5-硝基苯甲酸的新合成方法。从4-氟苯胺出发,经过盐酸-双氧水体系氯化、重氮化、氰化、硝化-水解串联反应共4步得到2-氯-4-氟-5-硝基苯甲酸,纯度96.2%,总收率59.2%。新合成方法原材料易得、条件温和,具有工业化应用前景。

18β-glycyrrhetinic acid inhibits proliferation of gastric cancer cells through regulating the miR-345-5p/TGM2 signaling pathway

BACKGROUND Gastric cancer(GC)is a common gastrointestinal malignancy worldwide.Based on cancer-related mortality,the current prevention and treatment strategies for GC still show poor clinical results.Therefore,it is important to find effective drug treatment targets.AIM To explore the molecular mechanism of 18β-glycyrrhetinic acid(18β-GRA)regulating the miR-345-5p/TGM2 signaling pathway to inhibit the proliferation of GC cells.METHODS CCK-8 assay was used to determine the effect of 18β-GRA on the survival rate of GES-1 cells and AGS and HGC-27 cells.Cell cycle and apoptosis were detected by flow cytometry,cell migration was detected by a wound healing assay,the effect of 18β-GRA on subcutaneous tumor growth in BALB/c nude mice was investigated,and the cell autophagy level was determined by MDC staining.TMT proteomic analysis was used to detect the differentially expressed autophagy-related proteins in GC cells after 18β-GRA intervention,and then the protein-protein interaction was predicted using STRING(https://string-db.org/).MicroRNAs(miRNAs)transcriptome analysis was used to detect the miRNA differential expression profile,and use miRBase(https://www.mirbase/)and TargetScan(https://www.targetscan.org/)to predict the miRNA and complementary binding sites.Quantitative real-time polymerase chain reaction was used to detect the expression level of miRNA in 18β-GRA treated cells,and western blot was used to detect the expression of autophagy related proteins.Finally,the effect of miR-345-5p on GC cells was verified by mir-345-5p overexpression.RESULTS 18β-GRA could inhibit GC cells viability,promote cell apoptosis,block cell cycle,reduce cell wound healing ability,and inhibit the GC cells growth in vivo.MDC staining results showed that 18β-GRA could promote autophagy in GC cells.By TMT proteomic analysis and miRNAs transcriptome analysis,it was concluded that 18β-GRA could down-regulate TGM2 expression and up-regulate miR-345-5p expression in GC cells.Subsequently,we verified that TGM2 is the target of miR-345-5p,and that overexpression of miR-345-5p significantly inhibited the protein expression level of TGM2.Western blot showed that the expression of autophagy-related proteins of TGM2 and p62 was significantly reduced,and LC3II,ULK1 and AMPK expression was significantly increased in GC cells treated with 18β-GRA.Overexpression of miR-345-5p not only inhibited the expression of TGM2,but also inhibited the proliferation of GC cells by promoting cell apoptosis and arresting cell cycle.CONCLUSION 18β-GRA inhibits the proliferation of GC cells and promotes autophagy by regulating the miR-345-5p/TGM2 signaling pathway.

固体酸SO42-/ZrO2催化果糖制备5-羟甲基糠醛

通过共沉淀-浸渍法制备了SO_(4)^(2-)/ZrO_(2)固体酸催化剂,探究了5种不同焙烧温度(450~650℃)对催化剂活性的影响,并采用X射线衍射(XRD)、透射电镜(TEM)、傅里叶红外光谱(FT-IR)等表征手段对催化剂的结构及理化性质进行了分析。研究表明:当焙烧温度高于450℃时,固体酸SO_(4)^(2-)/ZrO_(2)在2θ为30.1°均存在较为明显的四方相晶体结构;随着焙烧温度的升高,催化剂的孔径存在一定程度的增大,但比表面积总体呈降低趋势,酸强度也存在一定程度的降低。在焙烧温度为550℃焙烧3 h时制备的固体酸SZ-550表现出较好的催化性能,用于催化果糖脱水制备5-羟甲基糠醛(5-HMF)时,在反应温度为120℃,反应时间为90 min,催化剂用量为30 mg的最佳反应条件下,以二甲基亚砜(DMSO)为反应溶剂,果糖转化率为99.91%,5-HMF的得率为76.01%。XRD分析结果表明:固体酸SO_(4)^(2-)/ZrO_(2)明显的四方相ZrO_(2)结构是其表现出较高催化活性的原因之一。

Oleanolic acid inhibits colon cancer cell stemness and reverses chemoresistance by suppressing JAK2/STAT3 signaling pathway

Background:Oleanolic acid(OA),a pentacyclic triterpenoid exhibiting specific anti-cancer properties and highly effective antioxidant activity,was isolated from traditional Chinese medicinal herbs.Conversely,the OA that impacts colon cancer(CC)cells and its underlying mechanisms remain poorly understood.Methods:The cytotoxic effect of OA alone or OA-5-Fluorouracil(5-FU)combination on normal and CC cells was analyzed by methyl thiazolyl diphenyl-tetrazolium bromide(MTT).Then,the impact of OA on CC cell lines(LoVo and HT-29)proliferation and stemness were measured using colon formation and tumorsphere formation assays.Octamer-binding transcription factor 4(Oct4),Prominin-1(CD133),Nanog,and transcription factor SOX-2(SOX2)are cell stemness-related indicators whose expression was assessed usingfluorescence qPCR assay,Western blotting,and immunohistochemistry.The effect of OA on the proliferative potency of CC cells was evaluated using an in vivo model.Results:The stem-like characteristics and clone production of colon cancer cells were markedly reduced by OA alone or in combination with OA-5-FU.Moreover,OA increases the susceptibility of CC cells to 5-FU by blocking the cell stemness-related markers(CD133,Nanog,SOX2,and Oct4)expression levels both in vitro and in vivo,as well as by inactivating the activator of transcription 3(STAT3 signaling)and Janus kinase 2/signal transducer(JAK2).Conclusion:Thesefindings imply that oleanolic acid,both in vitro and in vivo,suppresses the JAK2/STAT3 pathway,which in turn reverses chemoresistance and decreases colon cancer cell stemness.Therefore,by reducing the recommended amount of 5-FU,this strategy may improve chemotherapeutic effectiveness and minimize undesired side effects.

3,5-二(2',5'-苯二羧酸)苯甲酸镍配合物的合成、结构及磁性

利用对称芳香多酸3,5-二(2',5'-苯二羧酸)苯甲酸(H_(5)L)和过渡金属镍,在水热法条件下,设计合成了一种新颖的金属有机配合物:{Ni(H_(3)L)(H_(2)O)}n(1),并通过单晶X射线衍射,红外光谱(IR),热重分析(TG)和粉末衍射对配合物1进行结构表征。结构分析表明1是基于多核[Ni(μ_(2)-H_(2)O)(μ_(2)-COO)(μ_(1)-COO)_(2)]_(n)SBUs的无限延伸的1D链状结构,并进一步通过π…π作用堆积成三维网络空间结构。磁性分析表明配合物1中的Ni(Ⅱ)离子之间存在反铁磁耦合作用。

Pig Liver Esterase-catalyzed Hydrolysis of Three Diesters of meso-Bicyclic Dicarboxylic Acid and Three Tetraesters of Tetrahydrofuran -2,3,4,5-tetracarboxylic Acid

Three diesters of exo- syn-meso-oxabicyclo (2, 2, 1 ) -hept- 5- ene- 2, 3- dicarboxylic acid and three tetraesters of tetrahydrofuran-2, 3, 4, 5-tetracarboxylic acid were synthesized and tested with enantioselective hydrolysis catalyzed by pig liver esterase(PLE). The results of the PLEcatalyzed hydrolysis were discussed.

Hydrothermal Syntheses and Crystal Structures of Six Complexes Constructed from 1,3,5-Benzenetricarboxylic Acid and 4'-(4-Pyridyl)-2,2':6',2''-terpyridine Mixed Ligands

Six new transition metal complexes, [Zn（HBTC）（PYTPY）]n·n PYTPY（1）, [Cu（HBTC）（PYTPY）]n·n PYTPY（2）, [Co（HBTC）（PYTPY）]n·n DMF（3）, [Mn（HBTC）（PYTPY）]n·n DMF（4）, [Cd（HBTC）（PYTPY）（H2O）]n·2nH2O（5）, and [Co（HBTC）（PYTPY）（H2O）2]（6）,（H3BTC = 1,3,5-benzenetricarboxylic acid, PYTPY = 4＇-（4-pyridyl）-2,2＇：6＇,2＇＇-terpyridine, DMF = N,N？-dimethylformamide）, have been synthesized and characterized by elemental analysis, IR and X-ray single-crystal diffraction. Complexes 1~5 all feature one-dimensional chain structures, and complex 6 exhibits a zero-dimensional structure. Complexes 1~5 present three-dimensional（3D） supramolecular frameworks via π-π stacking interactions, whenas 6 has also a 3D supramolecular structure assembled by hydrogen bonding. Meanwhile, complexes 1 ~ 6 exhibit the thermal stabilities and photoluminescent properties.

Effect of Temperature on the Reaction of 2-(N-acetylamine)-3-(3,5-di-<i>tert</i>-butyl-4-hydroxyphenyl)-propionic Acid with Oxygen in an Alkaline Condition

Results of oxidation 2-(N-acetylamine)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid oxygen depend on temperature. At 55℃?- 60℃, 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa is formed. The constitution is based on dates of spectrums 1Н and 13С NMR. At 95℃?- 97℃, mixtures of 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa and of 6,8-di-tert-butyl-3-(N-acetylamine)spiro(4,5)deca-1-oxa-5,8-dien-2,7-dione are produced. Structures are calculated by the method of Hartrii-Foka. Values of enthalpies and of entropies allow to assume dynamic isomerism.

EFFECT OF SnO_2 ADDITION ON THE SERVICE LIFE AND ELECTROCHEMICAL PROPERTIES OF Ti/IrO_2,+Ta_2O_5 ANODES IN PHENOLSULFONIC ACID SOLUTION

Service life of two different oxide anodes in phenolsulfonic acid (PSA) solution was investigated by accelerated electrolysis. The durability of Ti/IrO_2+Ta_2 O_5 anode increased by the addition of SnO_2 in the mixed oxides. The degradation mechanisms of Ti/IrO_2+ Ta_2 O_5 and Ti/IrO_2 +Ta_2 O_5 +SnO+2 anodes were different. It was shown from the observation of scanning electron microscopy (SEM) and the electrochcmical measurement that, the deactivation of Ti/IrO_2 + Ta_2 O_5 anode was due to the build-up of an organic film on surface. The growth of the covered film on surface was restricted by addition of SnO_2, which resulted in increasing of the service life of anodes. The over-potential for oxygen evolution on Ti/IrO_2 +Ta_2 O_5 electrode increased after doping SnO_2, and the intermediate products of PSA building-up on the surface was much more rapidly oxidized. Meanwhile, a certain part of the surface oxide deposit entered into the solution leading to loss of oxides, which resulted in degradation of Ti/IroO_2 + Ta_2 O_5 anode containing SnO_2 component.

Synthesis and Crystal Structure of One Mixed-ligand Coordination Polymer Based on the Novel Terphenyl-2,5,2',5'-tetracarboxylic Acid Ligand

Solvothermal reaction of aromatic terphenyl-2,5,2＇,5＇-tetracarboxylic acid （Hnqptc） ligand and the transitional metal cation of Mn11 in the presence of 3-（2-pyridyl）pyrazole （pp） affords one new coordination polymer, [Mn（qptc）0.5（pp）2]n·n（H2O） （1）. The structure has been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR, TGA, and magnetism. The carboxyl groups of qptc4 exhibit a μ1-η1：η0 coordination mode, and the qptc4- acts as a H-shaped ligand linking the Mn11 centers together to form a 2D polymeric [Mn（qptc）0.5]n layer. The crystal of 1 crystallizes in orthorhombic, space group Pbca with a = 9.3119（12）, b = 20.848（3）, c = 26.134（3） A, V= 5073.4（11） A3, Z= 8, C27HIgMnN6O5,Mr=562.42, Dc = 1.473 g/cm3, F（000） = 2304 and μ（MoKa） = 0.571 mm-1. The final R = 0.0468 and wR = 0.1196 for 4429 observed reflections with I 〉 2σ（I） and R = 0.0797 and wR = 0.1383 for all data.

A One-dimensional Cobalt Coordination Polymer Based on Biphenyl-2,3,3',5'-tetracarboxylic Acid and N-donor Ancillary Ligands: Crystal Structure and Magnetic Property

Hydrothermal reactions of biphenyl-2,3,3A,5A-tetracarboxylic acid（H4bptc） with cobalt salt in the presence of 1,4-bis（2-pyridylmethyl）piperazin（bpmp） afforded one novel coordination polymer, namely, [Co（H2bptc）（bpmp）0.5（H2O）]n（1）. Its structure was established by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analysis. Complex 1 crystallizes in monoclinic, space group P21/c with a = 11.4839（11）, b = 16.6690（16）, c = 11.5559（11） A, V = 2201.8（4） A3, Mr = 539.35, Dc = 1.627 g/cm^3, μ（MoK α） = 0.841 mm-1, F（000） = 1108, Z = 4, the final R = 0.0309 and w R = 0.0705 for 4090 observed reflections（I 2σ（I））. Complex 1 displays a one-dimensional（1D） chain bridged by bpmp. Two carboxylic groups of H4 bptc ligand adopt μ01-η1：η1 and μ1-η1：η coordination modes to bridge adjacent Co（Ⅱ） ions together with bpmp ligand to give alternately arranged left- and right-handed helical chains. In addition, variable-temperature magnetic susceptibility measurements indicate that complex 1 shows weak antiferromagnetic interactions between the adjacent Co（Ⅱ） ions.

磁性NiFe_(2)O_(4)负载Ru催化5-羟甲基糠醛选择性氧化合成2,5-呋喃二甲酸

采用水热-煅烧法制备了磁性镍铁尖晶石载体NiFe_(2)O_(4),再采用浸渍-还原法在载体上负载Ru纳米粒子制备Ru/NiFe_(2)O_(4)催化剂。采用X射线衍射(XRD)、N2吸附-脱附(BET)、NH3程序升温脱附(NH3-TPD)、H_(2)程序升温还原(H_(2)-TPR)、X射线光电子能谱(XPS)和电感耦合等离子体发射光谱(ICP-OES)测试对催化剂进行表征分析。结果表明,Ru/NiFe_(2)O_(4)催化剂表面氧物种丰富,相较于载体,负载Ru后催化剂比表面积和表面酸量增加,Ru与载体存在相互作用,这可能是催化剂高活性和高稳定性的关键。将催化剂用于5-羟甲基糠醛(HMF)的选择性氧化,负载Ru后,催化剂催化活性显著提升。对反应条件进行优化,在添加0.08 g KHCO3,氧化剂O2压力为1 MPa,反应温度为80℃,使用0.1 g Ru/NiFe_(2)O_(4)催化剂,在水溶液中反应12 h HMF能完全转化,2,5-呋喃二甲酸(FDCA)产率为98.1%。Ru/NiFe_(2)O_(4)循环使用5次后仍能保持较高的活性,催化剂上活性组分Ru不易浸出,并且催化剂具有磁性能便于与反应溶液分离。为今后工业化催化HMF高效选择性氧化合成FDCA提供参考。

Critical Amino Acid Residues for Nicotine 5'-Hydroxylation in Human CYP2A Enzymes

Objective： We have continued previous work in which we demonstrated that #117 and #372 amino acids contributed to the high activities of human CYP2A13 in catalyzing 4-methylnitrosamino-1-（3-pyridyl）-1-butanone（NNK） and aflatoxin BI（AFB1） carcinogenic activation. The present study was designed to identify other potential amino acid residues that contribute to the different catalytic characteristics of two CYP2A enzymes, CYP2A6 and CYP2A13, in nicotine metabolism and provide insights of the substrate and related amino acid residues interactions. Methods： A series of reciprocally substituted mutants of CYP2A6lle^300→ Phe, CYP2A6Gly^301aAla, CYP2A6Ser^369 → Gly, CYP2A13Phe^300→ Ile, CYP2A13Ala^301 → Gly and CYP2A13Gly^369 → Set were generated by site-directed mutagenesis/baculovirus-Sf9 insect cells expression. Comparative kinetic analysis of nicotine 5＇hydroxylatin by wild type and mutant CYP2A proteins was performed. Results：All amino acid residue substitutions at 300, 301 and 369 caused significant kinetic property changes in nicotine metabolism. While CYP2A6Ile^300→ Phe and CYP2A6Gly^301→Ala mutations had notable catalytic efficiency increases compared to that for the wild type CYP2A6, CYP2A13Phe^300→Ile and CYP2A13Ala^301→Gly replacement introduced remarkable catalytic efficiency decreases. In addition, all these catalytic efficiency alterations were caused by Vmax variations rather than Km changes. Substitution of #369 residue significantly affected both Km and Vmax values. CYP2A6Ser^369 → Gly increase the catalytic efficiency via a significant Km decrease versus Vmax enhancement, while the opposite effects were seen with CYP2A13Gly^369 → Ser. Conclusion：#300, #301 and #369 residues in human CYP2A6/13 play important roles in nicotine 5＇ -oxidation. Switching #300 or #301 residues did not affect the CYP2A protein affinities toward nicotine, although these amino acids are located in the active center. Set369 to Gly substitution indirectly affected nicotine binding by creating more space and conformational flexibility for the nearby residues, such as Leu^370 which is crucial for many hydroxylations.

Crystal Structure,Thermal Behavior and Magnetic Properties of a New Copper(Ⅱ) Complex Based on Biphenyl-2,5,2',5'-tetracarboxylic Acid

A new coordination polymer,[Cu2（bptc）（2,2＇-bpy） 2（H2O）]·H2O（2,2＇-bpy = 2,2＇-bipyridine,H4bptc = biphenyl-2,5,2＇,5＇-tetracarboxylic acid） ,has been synthesized under hydrother-mal conditions. The structure was characterized by single-crystal X-ray diffraction,elemental analysis,IR spectra and thermogravimetric analysis. It crystallizes in triclinic,space group P1 with a = 10.6447（12） ,b = 11.0191（12）,c = 16.1253（18）A,α = 79.538（2）,β = 88.0720（10） ,γ = 61.6650（10） °,V = 1634.1（3） A^3,C36H26Cu2N4O10,Mr = 801.69,Z = 2,Dc = 1.629 g/cm^3,μ（MoKα） = 1.370 mm^-1,F（000） = 816.0,R = 0.0418 and wR = 0.1135 for 4416 observed reflections with I 〉 2σ（I） . X-ray analysis shows that the title complex exhibits 1D wavelike [Cu2（bptc） ]n chains with two types of diamond-shaped pores. These 1D chains are linked into a 3D supramolecular structure via O-H···O,C-H···O interactions and weak π···π stacking interactions. There exist H-bonded helices in a right-and left-handed sequence by turns in a 2D layer. Moreover,thermal stability has been studied and magnetic measurements show antiferromagnetic interactions for this complex.