THE EFFECTS OF NEAR-UV RADIATION ON HUMAN LENS β-CRYSTALLINS: PROTEIN STRUCTURAL CHANGES and THE PRODUCTION OF O2_ and H2O2

beta-Crystallins (beta 1-, beta 2- and beta 3-crystallin) comprise nearly half the protein of the human lens. The effect of near-UV radiation, which is one of the possible risk factors in cataract formation, on the beta-crystallins is investigated in this study. Protein intersubunit crosslinking, change in charge of the protein subunits to more acidic species and changes in protein tertiary structure (conformation) by 300 nm irradiation are reported. The fluorescence yield of protein tryptophan residues decreases by 300 nm irradiation. There is an increase in nontryptophan fluorescence (lambda cx 340 nm, lambda cm 400-600 nm), and in protein absorption at 340 nm, due to the formation of tryptophan photooxidation products. Both tryptophan and its oxidation products can be photoexcited by 300 nm irradiation and the latter are known to be good photosensitizers. The results provide evidence for the generation of H2O2 in the irradiated human beta-crystallin solutions by the Type I photosensitizing action of the chromophores absorbing at 300 nm. The H2O2 is generated via the intermediate production of O2 anion; the latter spontaneously dismutates to H2O2, presumably via O2- protein interactions. The amount of H2O2 generated per absorbed photon is compared for various solutions of beta 1-, beta 2- and beta 3-crystallins from human lenses of different age.     

MECHANISMS FOR LUMINOL-AUGMENTED CHEMILUMINESCENCE FROM NEUTROPHILS INDUCED BY LEUKOTRIENE B4 AND N-FORMYL-METHIONYL-LEUCYL-PHENYLALANINE

Neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine (fMLP) or leukotriene B4 (LTB4) generated kinetically distinctive luminol augmented chemiluminescence (LCL). Inhibitors of .O2- [superoxide-dismutase (SOD) or tiron], H2O2 (catalase), myeloperoxidase, MPO, (NaN3), HOCl (taurine) and .OH (mannitol) hampered LCL dose-dependently with similar characteristics for both stimuli. In cell free systems it was found that .O2- (generated in the xanthine/xanthine-oxidase reaction) or H2O2 produced LCL. Superoxide dismutase inhibited .O2- -induced LCL dose dependently. The MPO + H2O2 system, which generated more pronounced LCL than either component alone, was inhibited by catalase and taurine but not by SOD. When neutrophils, treated with luminol, but where extracellular luminol had been removed, were stimulated with fMLP or LTB4, they produced less than 2% of the LCL where luminol was present in the medium. When neutrophil LCL and superoxide formation by the cytochrome C method were assessed in parallel experiments, in all instances the peak LCL response coincided with the linear phase in that response. Thus, LCL, induced by LTB4 and the corresponding fMLP peak, are extracellular events with similar chemical backgrounds, closely related to generation of reactive oxygen species. Consequently, the kinetical differences in LCL between fMLP and LTB4 suggest that LTB4, by yet unknown mechanisms, activates the NADPH oxidase more rapidly than fMLP.     

NiCo2O4对H2O2在碱性溶液中电化学还原反应的催化行为

利用溶胶-凝胶法合成纳米NiCo2O4,并利用X射线衍射和透射电镜分析其结构和表面形貌. 结果表明NiCo2O4具有尖晶石结构, 平均粒径约为15 nm. 利用电势线性扫描和恒电势法测定了其对H2O2在碱性溶液中电化学还原反应的催化性能. 发现NiCo2O4对H2O2电化学还原具有高的催化活性和稳定性, 在H2O2浓度低于0.6 mol·L-1时, 其电化学还原反应主要通过直接还原途径进行. 以NiCo2O4为阴极催化剂的Al-H2O2半燃料电池在室温下的开路电压达1.6 V; 在1.0 mol·L-1 H2O2溶液中, 峰值功率密度达209 mW·cm-2, 此时电流密度为220 mA·cm-2.     

RADIATION DEGRADATION OF CHITOSAN IN THE PRESENCE OF H2O2

INTRODUCTIONChitosan, poly-β-(1 -?4)-D-glucosamine, can be obtained from chitin by deacetylation with alkali. It is soluble indilute acidic medium due to the presence of amino groups. The use of chitosan in many areas, such as foodprocessing, biochemistry, Pharmaceuticals, medicine, and agriculture has been developed over the pastdecades[1,2].In recent years, it has been reported that many properties of chitosan depend on the molecular weight[3]. Thechitosan oligomers possess better fun…     

2MgO•2B2O3•MgCl2•14H2O-MgCl2-H2O体系30 ℃相平衡

用相平衡方法研究2MgO•2B2O3•MgCl2•14H2O 在30 ℃不同质量分数MgCl2 水溶液中的溶解转化产物及其溶解度. 结果表明, 该复盐在MgCl2的质量分数0～2％浓度范围, 发生不同步溶解并转化为多水硼镁石(2MgO•3B2O3•15H2O); 在MgCl2的质量分数2％～13.8％浓度范围, 转化为柱硼镁石(MgO•B2O3•3H2O), 这一结果比文献报导的该硼酸盐的形成温度低了13 ℃,为盐湖硼酸镁矿物柱硼镁石形成的解释提供了物理化学依据; 而在MgCl2质量分数大于13.8％时同步溶解,不发生转化. 提出了溶解相转化反应机理.     

Selective catalytic reduction of NO by C2H2 over Ce-Al2O3 catalyst with rate-determining step of NO oxidation

Ce-Al2O3 catalysts prepared by co-precipitation are investigated both in NO oxidation by O2 and in selective catalytic reduction of NO by C2H2(C 2 H 2-SCR).It is found that C2H2-SCR is initiated and controlled by NO oxidation to NO 2 over Al2O3.Ce loading on Al2O3 is almost inactive for NO oxidation below 350 C,since NO2 strongly adsorbs on cerium oxide,leading to the active sites being blocked,which was characterized by temperature-programmed desorption of NO and NO 2 and Fourier transform infrared spectroscopy after NO+O 2 coadsorption over the samples.However,in the case of C2H2-SCR,Ce loading on Al 2 O 3 significantly improves the reaction by accelerating the NO oxidation step in the temperature range of 250-450 C,since the nitrate species produced by NO 2 adsorption is an active intermediate required by C2H 2-SCR.     

有机锡配合物{[(n-C8H17)2Sn(O2CCH2CS2NC4H8O)]2O}2的合成，表征及晶体结构

The title complex {[(n-C₈H₁₇)₂Sn(O₂CCH₂CS₂NC₄H₈O)]₂O}₂ has been synthesized by the reaction of (morpholinylthiocarbamoylthio)acetic acid with the di-n-octyltin oxide in 1∶1 molar ratio. The complex was characterized by elemental analysis, IR and ¹H NMR. The crystal and molecular structure of complex was determined by X-ray single crystal diffraction. The crystal belongs to triclinic system with space group P1 and unit cell dimensions: a=1.201 5(9) nm, b=1.481 8(11) nm, c=1.894 1(14) nm, α=72.485(10)°, β=88.586(10)°, γ=66.893(9)°, and Z=1, μ=1.034 mm^-1, V=2.941(4) nm³, D_c=1.295 g·cm^-3, F(000)=1 196, R₁=0.058 8, wR₂=0.155 8. The complex is a centrosymmetric structure with a four-membered central endo-cyclic Sn₂O₂ unit in which two bridged oxygen atoms both connect with an exo-cyclic tin atom. The endo-cyclic tin atoms and the exo-cyclic tin atom are all five-coordinate and have coordination geometry of distorted trigonal bipyramid with an additional weak coordination carboxylate oxygen. Four carboxylate ligands are divided into two types. And two of them are monodentate and connecting to each of exo-cyclic tin atoms by using one oxygen atom, whereas the others bridge to each pair of exo-and endo-cyclic tin atoms utilizing one oxygen atom. CCDC: 277048.     

THE QUENCHING OF TYROSINE AND TRYPTOPHAN FLUORESCENCE BY H2O AND D2O*

Abstract— The quantum yields and lifetimes of the fluorescence of tyrosine and tryptophan were determined in D₂O-H₂O and glycerol-H₂O solvent mixtures of varying composition from 10 vol.% to 100% H₂O at 15°C. Forboth amino acids the ratio of the quantum yields in D₂O and H₂O (i.e., q_D/q_H) was smaller than the ratio of the corresponding lifetimes (_D/_H). For tyrosine the ratio of the quantum yields in glycerol and H₂O (q_G/q_H) was also smaller than the corresponding _G/_H ratio, but for tryptophan q_G/g_HG/_H. The proximity of the q vs. plots for tyrosine in the two solvent mixtures indicates that at 15°C neither D₂O nor glycerol, in the pure state or when diluted with H₂O, quench tyrosine significantly. However, H₂O quenches tyrosine by a dynamic process, which increases both the radiative and the nonradiative rate constant. The quenching action is attributed to a tyrosine-H₂O exciplex, whose formation is independent of bulk viscosity and dielectric constant. Unlike tyrosine, tryptophan is quenched weakly by D₂O by a static process at 15°C (i.e., involving no change in), but H₂O quenches tryptophan much more efficiently by a dynamic process, which involves the nonradiative rate constant, but not the radiative constant. These results are explained on the basis of electrostatic complexation of the ammonium group to the carbon atom adjacent to the ring nitrogen with a lifetime which is longer thanin D₂O but shorter thanin H₂O, with solvent reorientation possibly also being an important factor in the quenching. This explanation is consistent with the fact that concentrated (8 M) urea increases q andof aqueous tryptophan ? 15–20%, while guanidine hydrochloride (6.4 M) has the opposite effect, i.e., it decreases q and t of tryptophan ? 15–20%, and with the fact that neither 8 M urea nor 6.4 M guanidine hydrochloride affects any fluorescence parameter of tyrosine at all.     

三维结构多金属氧酸盐Ag4H3PTi2W10O40·16H2O的合成与表征

以Keggin型钛取代钨磷酸钾和醋酸银为反应物合成了1个新的多金属氧酸盐Ag4H3PTi2W10O40.16H2O(1),通过X射线单晶衍射分析确定了其晶体结构,通过ICP分析和热重分析确定了其组成,通过红外光谱和固体漫反射光谱表征了其性质.单晶结构分析表明,化合物1属于四方晶系,I4/m空间群,晶胞参数a=b=1.39905(13)nm,c=1.14358(18)nm,V=2.2384(5)nm3,Z=2,R1=0.0550,wR2=0.1590.化合物1中的Ag+均为六配位,每个Ag+同时与3个多阴离子上的2个端氧和4个桥氧配位形成{AgO6}单元,这些{AgO6}将该多阴离子连接成三维网络结构.     

[Pb2(TNR)2(CHZ)2(H2O)2]4H2O的结构及热分解机理

The coordination compound of [Pb 2(TNR) 2(CHZ) 2(H 2O) 2]•4H 2O was prepared by using the aqueous solution of carbohydrazide, lead nitrate and sodium styphnate. The molecular structure of [Pb 2(TNR) 2(CHZ) 2(H 2O) 2]•4H 2O(C 7H 13 N 7O 12 Pb, Mr=594.43) was determined by using a single crystal diffraction analysis .The thermal decomposition mechanism of the title compound was studied by TGDTG, DSC and IR techniques. The crystal belongs to monoclinic with space group P2 1/n.The unit cell parameters are as follows: a=0.64700(10)nm, b=1.6074(3)nm, c=1.4883(3)nm,β=97.42(2)°,V=1.5349(5)nm3, Z=2, DC=2.572g•cm -3 ,μ(Mo, Kα)=11.080cm -1 , F(000)=1128. R=0.0422, Rw=0.0735. The binuclear lead coordination compound is bridged by two carbohydrazide molecules. The molecule has a symmetrical center. TNR 2- ,CHZ and H 2O coordinate with the central ions simultaneously.     

四水合均苯三甲酸二氢钴的合成、结构和磁性

利用水热法在均苯三甲酸、六水氯化钴、甲酸铵和水的体系中合成了四水合均苯三甲酸二氢钴。该化合物晶体属于单斜晶系,对应的空间群为P2₁/c。磁性测量表明该化合物的钴离子之间存在反铁磁的相互作用,但直至2 K时也没有观察到磁有序。     

La2O3对Ni/γ-Al2O3甲烷化催化剂的助催化作用

我国将稀土作为助剂引入镍基甲烷化催化剂,大大提高了催化剂的活性和热稳定性,并已投入工业应用［1－3］．稀土对不同镍催化剂反应性能及其作用机理的研究已有一些报导［3－7］．谢有畅等观察到镍负载在经单层La2O3改性的γ－Al2O3表面,其晶粒要比没有La2O3时小得多．Rotgerink等认为添加La后反应速率的增加不只是由于几何效应,而是La对甲烷化本身有促进作用,单位镍表面的活性是随La含量不同而改变的,活性增加的同时表观活化能也增加［5］．作为助剂的La2O3在氢还原和反应过程中的变化及其作用的研究和讨论较少,目前一般认为添…     

H2O、CO2组分对NOx存储-还原性能的影响

NOx存储-还原技术是控制汽车稀燃NOx排放的重要手段之一,在汽车尾气中H2O、CO2组分含量均相对较高,有必要弄清这些组分对NOx存储-还原特性的影响。论文以MnOx改性Pt/Ba/Al2O3催化剂为研究对象,评价在不同气氛下的NOx存储能力和催化还原性能。结果表明：CO2、H2O组分均抑制催化剂的NOx存储性能,H2O的抑制作用主要表现在低温区,CO2抑制NOx存储的现象在高温区更为显著。CO2对NOx存储速率的抑制作用较H2O更为明显,且其NOx存储速率随着温度的升高表现的差异性更为明显。对于NOx催化还原过程,CO2、H2O或CO2 H2O添加均导致N2选择性降低,其N2选择性按CO2 > H2O > CO2 H2O的顺序降低。     

PHOTOINACTIVATION OF A Chlamydomonas MUTANT(NL–11) IN THE PRESENCE OF METHIONINE: ROLES OF H2O2 and O-2

Abstract— A mutant of Chlamydomonas reinhardtii (NL–11) isolated from a wild type (137c+) was inactivated in the light in the presence of methionine at concentrations where the wild type was not inactivated. The inactivation was suppressed by either catalase or superoxide dismutase (SOD). Light-induced H₂O₂ formation and nitroblue tetrazolium (NBT) reduction inNL–11 were greater than those in the wild type. Methionine stimulated both the H₂O₂ formation and the NBT reduction inNL–11 as well as the wild type. The light-induced NBT reduction inNL–11 in the presence of methionine was partially suppressed by externally added SOD suggesting the participation of O^-₂. These results suggest that the hypersensitivity ofNL–11 to methionine in the light is due to stimulated formation of H₂O₂ and O^-₂.     

Mg2+, K+//Cl-, B4O2-7-H2O四元体系288 K固液相平衡

采用等温溶解平衡法研究了288 K时Mg2+, K+//Cl-, B4O2-7-H2O四元体系的相平衡关系, 测定该体系在288 K时平衡液相的溶解度和密度. 依据实验测定的平衡溶解度数据及对应的平衡固相, 绘制了该四元体系的平衡相图以及其密度-组成图. 研究结果表明, 四元体系Mg2+, K+//Cl-, B4O2-7-H2O 288 K时的固液相平衡实验中, 有复盐KCl·MgCl2·6H2O生成, 平衡相图中有3个共饱点, 7条单变量曲线, 5个结晶区, 对应的平衡固相分别为MgB4O7·9H2O, K2B4O7·4H2O, KCl, MgCl2·6H2O, KCl·MgCl2·6H2O. 简要讨论了实验结果.     

纳米Li_2ZrO_3吸收剂原位移除CO_2强化水煤气变换反应制氢

采用浸渍法制备了在水煤气变换(WGS)反应中具有高催化活性的Ni/γ-Al2O3催化剂,使用柠檬酸法合成出高效CO2吸收剂Li2ZrO3纳米材料.在固定床微反应器上对WGS和吸附强化水煤气变换(SE-WGS)反应制氢过程进行了比较研究.前者只使用20%Ni/γ-Al2O3催化剂,而后者将20%Ni/γ-Al2O3催化剂与纳米Li2ZrO3吸收剂混合装填.结果表明,纳米Li2ZrO3具有比已报道的CO2吸收剂更快的吸收速率及优异的吸脱附循环稳定性,可应用于吸附强化过程,通过原位吸收WGS反应产生的CO2,使得反应超越化学平衡限制,直接制得高纯度H2.在823K,0.1MPa和H2O/CO=4的条件下,在SE-WGS过程一步制得纯度高于98%的H,验证了吸附强化反应进程制高纯氢的可行性.     

三维超分子[Ni(hmt)2(SCN)2(H2O)2][Ni(SCN)2(H2O)4](H2O)2的自组装,晶体结构及磁性质(hmt=六次甲基四胺)

Compound [Ni(hmt)₂(SCN)₂(H₂O)₂][Ni(SCN)₂(H₂O)₄](H₂O)₂ (hmt=hexamethylenetetramine) was pre-pared and structurally characterized by means of X-ray single crystal diffraction. The two neutral units [Ni(hmt)₂(SCN)₂(H₂O)₂] and [Ni(SCN)₂(H₂O)₄] are joined together through hydrogen bonds N…H-O, O…H-O and S…H-O. In the solid state, the compound has three-dimensional network structure. The determination of its variable-temperature magnetic susceptibilities (5～300K) shows that the magnetic behavior obeys the Curie-Weiss law over the whole temperature ranges.     

二维层状结构十钒酸盐[K(H2O)2Ni(H2O)6]2[V10O28]的合成及性质(英)

A novel heteropoly compound, containing two kinds of coordinated cations, [K(H₂O)₂Ni(H₂O)₆]₂[V₁₀O₂₈], has been synthesized through routine process and characterized by elemental analyses, IR, ⁵¹V NMR and single crystal X-ray diffraction. It crystallizes in the triclinic system, space group P1 with a=0.87382(17) nm, b=1.075 4(2) nm, c=1.111 1(2) nm, α=65.10(3)°, β=75.01(3)°, γ=70.63(3)°, V=0.884 8(3) nm³ and Z=1. The X-ray analysis reveals that the two kinds of coordinated cations are linked by three shared coordinated water molecules, and K⁺ cations coordinate with ten oxygen atoms: five of which come from V₁₀O₂₈^6- anion, the other five from water molecules. The title compound exhibits extended 2D array building up of V₁₀O₂₈^6- groups connected by ten-coordinated K⁺ cations. The hexahydrated nickel cations Ni(H₂O)₆²⁺ lie in neat apposition to three adjacent V₁₀O₂₈^6- clusters. CSD: 413271.     

CH2+O2反应的反应机理

The mechanisms of the CH2＋ O2→ H2O＋ CO and CH2＋ O2→ H2＋ CO2 reactions have been studied by performing ab initio CAS(8,8)/6-31G(d,p) calculations, and five intermediates(IMn) and eight transitions(TSn) have been located along the reaction paths. The predicted path for the CH2＋ O2→ H2O＋ CO is: CH2＋ O2→ TS1→ IM1→ TS2→ IM2→ TS3→ IM3→ TS4→ IM4a→ TS5→ H2O＋ CO. For the CH2＋ O2→ H2＋ CO2 reaction, there are two paths: (i) CH2＋ O2→ TS1→ IM1→ TS2→ IM2→ TS3→ IM3→ TS6→ H2＋ CO2 and (ii) CH2＋ O2→ TS1→ IM1→ TS2→ IM2→ TS3→ IM3→ TS4→ IM4a→ TS7→ IM4b→ TS8→ H2＋ CO2, with the latter path more favorable energetically.     

鼓形有机锡氧杂环羧酸簇合物[PhCH2Sn(O)(O2CC4H3S)]6·2CH2Cl2 和 [PhCH2Sn(O)(O2CC3H2NO)]6·2CH2Cl2的合成和晶体结构

利用三苄基氧化锡与2-噻吩甲酸和2-唑甲酸反应,合成了六聚体苄基锡氧2-噻吩甲酸酯(1)和六聚体苄基锡氧2-唑甲酸酯(2)鼓形簇合物.通过元素分析、红外光谱和X射线单晶衍射对其结构进行了表征.测试结果表明:化合物1属三斜晶系,空间群p1,a=1.2760(3)nm,b=1.3056(3)nm,c=1.3343(3)nm,α=105.65(3)°,β=96.27(3)°,γ=97.20(3)°,Z=1,V=2.0997(7)nm3,Dc=1.809g/cm3,μ=2.097mm-1,F(000)=1116,R=0.0651,wR=0.1292.化合物2属三斜晶系,空间群p1,a=1.2240(4)nm,b=1.3673(4)nm,c=1.3744(4)nm,α=107.760(4)°,β=98.069(5)°,γ=91.480(5)°,Z=2,V=2.1631(12)nm3,Dc=3.373g/cm3,μ=3.799mm-1,F(000)=2136,R=0.0382,wR=0.079.它们均为鼓形簇状结构,锡原子呈畸变的八面体构型.化合物1通过分子间S…S近距离作用,形成一维链状结构.