A theoretical study of the proton transfer process in the spin-forbidden reaction ^1HNO（^1A＇） ＋ OH^-→^ 3NO^-（^3∑^-） ＋ H2O

The spin-forbidden reaction 1HNO（^1A＋OH^-→3NO^-（^3∑^-）＋H2O has been extensively explored using vari- ous CASSCF active spaces with MP2 corrections in several basis sets. Natural bond orbital （NBO） analysis, together with the NBO energetic （deletion） analysis, indicates that the two isomers have nearly equal total energy and could compete with each other in the title reaction. More significantly, the singlet/triplet surface crossing regions have been examined and the spin-orbit coupling （SOC） and energetics have been computed. The computational results indicate that the SOC is very large at the crossing point T1/S0 trans （ca. 40.9 cm^-1）. Moreover, the T1/S0 trans has a low energy of 10.67 kcal/mol relative to that of trans-So. Therefore, the surface crossing to the triplet state seems much more efficient at the T1/S0 trans region along the minimum energy path （MEP）, However, The values of single （P1^ISC） and double （P2^ISC） passes estimated at T1/S0 trans show that the ISC occurs with a little probability.     

Na_3AlF_6-AlF_3-Al_2O_3-CaF_2-LiF-NaCl系电解质密度的研究

研究了电解质中加入氯化钠,并用氯化钠取代部分氟化锂的电解质体系的密度.采用电子天平与计算机串口相结合的测量技术,根据阿基米德定律确定电解质体系的密度,误差小于1%.利用该方法,通过四因素四水平正交实验研究了Na3AlF6-AlF3(10.87%~16.67%)-Al2O3(3%)-CaF2(4%)-LiF(0~6%)-NaCl(0~8%)体系电解质密度,并且根据测量结果建立了该体系的密度数学模型:tρ(g.cm-3)=2.897 1-0.003 07AlF3(w/%)+0.003 041LiF(w/%)-0.009 32NaCl(w/%)-0.000 85t(℃).分析了不同分子比、氟化锂添加...     

Synthesis and application of bilayer-surfactant-enveloped Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles: water-based bilayer-surfactant-enveloped ferrofluids

Superparamagnetic carbon-coated Fe₃O₄ nanoparticles with high magnetization (85 emu·g-1) and high crystallinity were synthesized using polyethylene glycol-4000 (PEG (4000)) as a carbon source. Fe₃O₄ water-based bilayer-surfactant-enveloped ferrofluids were subsequently prepared using sodium oleate and PEG (4000) as dispersants. Analyses using X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy indicate that the Fe₃O₄ nanoparticles with a bilayer surfactant coating retain the inverse spinel-type structure and are successfully coated with sodium oleate and PEG (4000). Transmission electron microscopy, vibrating sample magnetometry, and particle-size analysis results indicate that the coated Fe₃O₄ nanoparticles also retain the good saturation magnetization of Fe₃O₄ (79.6 emu·g-1) and that the particle size of the bilayer-surfactant-enveloped Fe₃O₄ nanoparticles is 42.97 nm, which is substantially smaller than that of the unmodified Fe₃O₄ nanoparticles (486.2 nm). UV–vis and zeta-potential analyses reveal that the ferrofluids does not agglomerate for 120 h at a concentration of 4 g·L-1, which indicates that the ferrofluids are highly stable.     

Cesium accumulation by bacterium Thermus sp. TibetanG7： hints for biomineralization of cesiumbearing geyserite in hot sprinss in Tibet, China

The bacterium Thermus sp. TibetanG7, isolated from hot springs in Tibet, China, was examined for the ability to accumulate cesium from solutions. Environmental conditions were simulated and the effects of pH, K^＋, Na^＋and K^＋-regimes were then studied to determine the possible role of the bacterium in the formation of cesium-bearing geyserite around these hot springs. In despite of the inhibition of K^＋ and Na^＋, the bacterium Thermus sp. TibetanG7 revealed noticeable accumulation of cesium from solutions, with maximum accumulations of 53.49 and 40.41 pmol Cesium/g cell dry weight in Na^＋ and K^＋ inhibition experiments, respectively. The accumulation of cesium by this microorganism is rapid, with 40% --50% accumulated within the first 5 min. K^＋-deficient cells showed a much higher capacity of cesium accumulation compared with K^＋-sufficient cells. It is evident that the bacteria within the genus thermus play a significant role in the cesium assembly. The formation of cesium-bearing geyserite is also considered.     

Surface modification of γ-Al2O3 by sodium ions

¹H/²³Na double resonance NMR techniques were employed to study the modification of surface hydroxyls on γ-Al₂O₃ by sodium ions. ¹H→²³Na cross polarization (CP) experiment can resolve three kinds of sodium cations that are closely associated with surface hydroxyl groups, while the signal of deposited salt-Na₂CO₃, which is not connected to surface hydroxyl groups, is completely suppressed. ¹H{²³Na} spin echo double resonance experiments reveal the surface modification in more detail. At low Na⁺ coverage (5%, 10%), the acidic hydroxyl groups are preferentially coordinated with sodium ions, while both the acidic and the basic hydroxyl groups are accessible for sodium ions at high coordination that causes proton of the OH groups to be easily dissolved, which is evidenced by the fact that with calcination temperature of the catalysts increasing, the acidic hydroxyl groups are preferentially removed and only the basic hydroxyl groups remain when the calcination temperature is raised to 600℃.     

石墨相氮化碳表面包覆改善锂离子电池正极材料LiCoO2电化学性能的研究

通过简单的固相法和液相法,分别制备出石墨相氮化碳（g-C₃N₄）表面改性的商品化LiCoO₂复合材料,采用扫描电子显微镜观察改性后的材料,发现g-C₃N₄都均匀地包裹在LiCoO₂表面。两种g-C₃N₄-LiCoO₂复合材料被用作锂离子电池的正极材料,电化学测试结果显示,固相法制得的g-C₃N₄-LiCoO₂复合材料在0.2 C的倍率下充放电测试,首次比容量达167 mA·h·g^-1,循环80次后,比容量仍达132 mA·h·g^-1,高于未经g-C₃N₄包裹的纯LiCoO₂（98 mA·h·g^-1）;液相法制得的Y-C₃N₄-LiCoO₂复合材料循环稳定性明显优于同类材料,循环80次后容量保持率均在95%以上。试验证实,g-C₃N₄表面改性的策略具有一定的实用价值,改性后,材料优异的电化学性能归因于g-C₃N₄的包裹处理,这不仅增强了固体电解质界面（SEI）的稳定性,也抑制了锂离子嵌入/脱出电极材料时引起LiCoO₂体积的变化。     

氮化碳自组装包裹对SnO2TiO2复合锂离子电池负极材料电化学性能的影响

通过简单的石墨相氮化碳(g-C₃N₄)纳米片自组装沉积法,制备了g-C₃N₄包裹的SnO₂-TiO₂纳米复合材料.扫描电子显微镜观察显示,g-C₃N₄均匀地包裹在SnO₂-TiO₂纳米颗粒上.SnO₂-TiO₂-C₃N₄纳米复合材料被用作锂离子电池的负极材料,在0.2C的倍率下循环20次后,比容量达到380.2 mA·h·g^-1,明显高于未经g-C₃N₄包裹的纯的SnO₂(51.6 mA·h·g^-1)和SnO₂-TiO₂纳米复合材料.在0.1~0.5C的倍率充放电测试中,SnO₂-TiO₂-C₃N₄纳米复合材料的比容量仅从490 mA·h·g^-1衰减到330 mA·h·g^-1,高倍率下抗衰减性能优于同类材料.材料优异的电化学性能归功于g-C₃N₄的包裹处理,这不仅增强了固体电解质界面(SEI)的稳定性,也抑制了锂离子嵌入-脱出时SnO₂和TiO₂纳米颗粒的体积变化.     

Kinetics of C2(a3Πu) radical reactions with NO, N2O, O2, H2 and NH3

Pulsed laser photolysis/laser-induced fluorescence (LP-LIF) is utilized to measure rate constants for C₂(a³Π_u) reactions with NO, N₂O, O₂, H₂ and NH₃. Multiphoton dissociation of C₂Cl₄ at 266 nm is employed for the generation of C₂(a³Π_u) radicals. The C₂(a³Π_u) concentration is monitored by the fluorescence of the (0, 0) band of the (d³Π_g&#8596;a³Π_u) transition at 516.5 nm. C₂(a³Π_u) removal rate constants for the reactions are determined as k_NO = (5.46 ± 0.10) × 10^-11 cm³ molecule^-1 s^-1 , k_N2O = (1.63 ± 0.20) × 10^-13 cm³ molecule^-1 s^-1 , k_N2O = (1.58 ± 0.16) × 10^-11 cm³ molecule^-1 s^-1, k_O2 = (5.92 ± 1.00) × 10^-14 cm³ molecule^-1 s^-1, k_H2< 1.0× 10^-14 cm³ molecule^-1 s^-1. Based on the data analysis and theoretical calculation, we suggest that the C₂(a³Π_u) reactions with H₂ and NH₃ proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions of C₂(a³Π_u) with H₂ and NH₃.     

龙匙片降血糖作用的实验研究

【目的】龙匙方是广西壮族自治区人民医院俞祝全医生的临床经验方,本文研究其对正常小鼠及几种糖尿病模型小鼠降血糖的作用。【方法】采用链脲佐菌素致糖尿病、肾上腺素致高血糖、大剂量口服葡萄糖致高血糖小鼠模型,分别观察龙匙片对正常和糖尿病模型小鼠血糖的影响。【结果】高、中剂量组(11500mg·kg~(-1)·d~(-1)、5750mg·kg~(-1)·d~(-1))龙匙片对链脲佐菌素致糖尿病、肾上腺素致高血糖、大剂量口服葡萄糖致高血糖小鼠的血糖具有明显的降低作用;但高、低剂量(11500mg·kg~(~(-1))·d~(-1)、3060mg·kg~(-1)·d~(-1))龙匙片对正常小鼠血糖水平均无明显影响(P0.05)。【结论】龙匙片对糖尿病模型小鼠具有降低血糖的作用。     

超声波下酸化碘酸钾和亚硫酸钠反应的反应速率研究

分别测定在有超声波作用和在无超声波作用条件下 ,酸化碘酸钾 (KIO3 )和亚硫酸钠 (Na2 SO3 )反应的反应速率方程式及活化能 ,从而研究该反应的机理以及超声波在该反应中的作用 ,并确定反应的最佳条件。实验得出 ,超声波对该反应有一定的促进作用 ,但是这种促进作用只提高反应的速率常数和降低反应的活化能 ,并没有改变反应机理。在超声波功率为 30 0W时 ,反应的速率方程表示式为 :v =k·c1 0 9(KIO3 ) ·c1 0 0 (Na2 SO3 )·c1 0 8(H+ ) ,其中 :k =95 0 (mol-1·L) 2 ·s-1,活化能为 17 35kJ·mol-1。实验还得出 ,在温度为2 98K时 ,当KIO3 与Na2 SO3 的初始浓度比为 2∶5 ,H+ 的初始浓度为 0 0 4 2 8mol·L-1,超声功率为 30 0W时 ,反应速率为最快 ,即v =4 31× 10 -4mol·L-1·s-1)。     

Scalable synthesis and electrochemical performance of mesoporous graphene from calcium carbonate by magnesiothermic reaction

A novel scalable synthetic method of mesoporous graphene has been developed using the compressed mixture of Mg and excess CaCO₃ in a closed container. The generated solid oxide and unreacted CaCO₃ could act as mesopore-forming agents, and the closed container could prevent the carbon dioxide from CaCO₃ flow away. As a result, the graphenes with a large number of 2–30 ?nm mesopores and high utilization ratio of Mg achieved. The graphenes had high specific surface area and excellent electrochemical performance. In particular, the Mg utilization ratio was up to 53.3% in the preparation of graphene using 2:1 CaCO₃/Mg at 700 ?°C, which is superior to previous researches. The obtained mesoporous graphene exhibited high specific surface area of 743.7 ?m² ?g^-1, large specific capacitance of 140 ?F ?g^-1, and high capacitance retention rate of 64.3%.     

Isolation by phage display and characterization of a single-chain antibody specific for O6-methyldeoxyguanosine

New approaches of making single chain Fv antibodies against O⁶-methyl-2′-deoxyguanosine (O⁶MdG) have been demonstrated by using the phage antibody display system. Using O⁶MdG as an antigen, 21 positive clones were identified by ELISA from this library, one of which, designated H3, specifically binds to O⁶MdG with high affinity. The H3 scFv antibody has an affinity constant (K_aff) of 5.94×10O¹¹(mol/L)^-1. H3 scFv has been successfully used to detect O⁶MdG in DNA hydrolyses from yeast or E. coli cells treated with a DNA methylating agent. To our knowledge, this is the first report of the selection of a specific scFv against DNA adducts. The results demonstrate the potential applications of the phage display technology for the detection of DNA lesions caused by mutagens and carcinogens.     

秀丽线虫对根际益生菌P13和S3-1传播作用及对植物生长的影响

通过缓慢杀线实验、偏好性实验和共培养毒性实验分析了秀丽线虫(Caenorhabditis elegans)对荧光假单胞菌P13(Pseudomonas fluorescens P13)和解淀粉芽孢杆菌S3-1(Bacillus amyloliquefaciens S3-1)传播的可能性.通过显微观察与平板稀释涂布对秀丽线虫细菌携带作用进行了定性、定量分析,并对细菌—线虫—植物三者交互作用进行初步探究.结果发现,P13和S3-1对秀丽线虫的慢性致死率分别为12.12%和3.00%,每10 s身体弯曲次数分别为4.68和4.33.相对于尿嘧啶缺陷型大肠杆菌(OP50),线虫对P13和S3-1选择系数分别为0.13和0.52,P13、S3-1携带菌量分别为(4.02×103±47)和(9.67×102±22)CFU/条.携细菌线虫将细菌定向传播至植物根际,细菌定殖菌量为105CFU,有效促进植物生长发育.     

基于美国高加索人群瘦体重的全基因组关联研究

为了寻找与瘦体重相关的单核苷酸多态性(SNP)位点及易感基因,在2 283名不相关的美国高加索人群中对瘦体重指数(LMI)进行全基因组关联分析(GWAS),并在1 000名不相关的美国高加索人群中验证,将研究结果与验证结果进行荟萃分析。研究发现,位于19p13.3区域的UQCR, MBD3和TCF3基因与LMI相关联。UQCR基因上rs8697(合并p=4.94×10~(-3))和rs56122285(合并p=2.59×10~(-3))具有eQTL效应,MBD3基因上rs8110543(合并p=6.88×10~(-3))和rs7252741(合并p=1.22×10~(-2))具有eQTL效应,DB得分分别为1b和1f。本研究进一步证实了UQCR,MBD3和TCF3基因在瘦体重变异中的作用,对肌少症的认识提供新的理论依据。     

Hf isotopic compositions of the standard zircons for U-Pb dating

Zircon, a common accessory mineral in various kindsof rocks, is an important subject for U-Pb isotopic dating.With requirements for high spatial resolution with highprecision and accuracy, SHRIMP (Sensitive High Resolu-tion Ion Micro Probe) and LA-ICPMS (Laser AblationInductively Coupled Plasma Mass Spectrometry) nowserve as the important tools in zircon U-Pb dating. Sinceboth methods need standard zircon for external age cali-bration, an ideal standard zircon is critical for obtai…     

Application of upconversion luminescence in dye-sensitized solar cells

An upconversion luminescence powder TiO2:(Er3+,Yb3+) is prepared by a hydrothermal method and used to fabricate dye-sensitized solar cell (DSSC).The TiO2:(Er3+,Yb3+) powder undergoes upconversion luminescence,converting infrared light which the dye can not absorb into visible light with wavelengths of 510-700 nm which the dye can absorb,increasing the photocurrent of the DSSC.TiO2:(Er3+,Yb3+) also acts as a p-type dopant,heightening the Fermi level of the oxide film,which increases the photovoltage of the DSSC.The best performance of the DSSC is found when the ratio of TiO2/luminescence powder is 1/3 in the luminescence layer.Under simulated solar irradiation of 100 mW cm-2 (AM 1.5),the DSSC containing TiO2:(Er3+,Yb3+) doping achieves a light-to-electricity energy conversion efficiency of 7.28% compared with 6.41% for the undoped DSSC.     

The 3rd-order nonlinearity of bacteriorhodopsin by four-wave mixing

The 3rd-order nonlinear optical susceptibility X(³) and the response time of the light-transducing biomolecule bacteriorhodopsin were measured with the four-wave mixing technique and a picosecond frequency-doubled Nd: YAG laser (532 nm). TheX ³) and the response time measured are 10^-9 esu and 20 ps, respectively. The possible mechanism for generating the 3rd-order nonlinear optical susceptibility X(³) and response time were discussed.     

α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘的合成和晶体结构

 在酸性介质中,3,4-二乙酰基-2,5-己二酮与萘胺作用,合成得到了α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘,用IR,1H-NMR,MS,HRMS对其进行了表征,并用X射线衍射测定了α-(2,5-二甲基-3,4-二乙酰基吡咯基)萘的晶体结构.该晶体属三斜晶系,P1空间群,晶体学数据为:a是0.8045(1)nm,b是1.0018(1)nm,c是2.0757(2)nm,α是80.09(1)°,β是82.66(1)°,γ是83.81(1)°,V是1.6281(3)nm³,Z是4,M_r是305.36,D_c是1.246×10³kg/m³,μ(M_oK_α)是0.080mm^-1,F(000)是648,在I>2σ(I)的独立可观测衍射点为3669个,最终偏差因子R是0.0406,W_R是0.0962.     

磁性FeNi合金/石墨化介孔碳纳米复合材料的合成及其在染料吸附中的应用

以介孔SBA-15为模板,金属硝酸盐作为磁性FeNi合金纳米颗粒前驱物,采用纳米铸造法合成出一系列磁性FeNi合金/石墨化介孔碳纳米复合材料.利用X射线衍射仪(XRD)、N₂吸附-脱附仪(BET)、电感耦合等离子体质谱仪、透射电子显微镜(TEM)、振动样品磁强计(VSM)和热重分析仪(TG)等对合成物进行表征.结果发现,试验得到的纳米复合材料具有一致的介孔结构,高含量的磁性FeNi合金纳米晶体(尺寸大约是3~6 nm)均匀分散在石墨介孔碳模型的壁上,此介孔材料具有高的比表面积(360.3~431.9 m²·g^-1),大孔体积(0.558~0.718 cm³·g^-1)和高饱和磁化强度(18.2~42.1 emu·g^-1).基于以上特性,研究了材料对于水中染料的吸附性能.结果发现,当染料浓度为50 mg·L^-1时,材料对其去除率接近100%,同时在外加磁场存在时,悬浮液可以很好地实现固液分离.因此,磁性FeNi合金/石墨化介孔碳纳米复合材料在去除废水中的染料方面可以作为高效和可循环使用的吸附剂.     

Synthesis,characterization and photoluminescence of aluminum <Emphasis Type="Italic">N</Emphasis>-aryloxo functionalized <Emphasis Type="Italic">β</Emphasis>-ketoiminate complexes

The synthesis, characterization and luminescent properties of aluminum complexes containing a dianionic N-aryloxo functionalized β-ketoiminate ligand are presented. 4-(2-Hydroxy-5-R-phenyl)imino-2-pentanone (R = Me, L¹H₂; R = tert-butyl, L²H₂) ligands reacted with AlEt₃ in tetrahydrofuran to give the aluminum complexes (L¹AlEt)₂ (1) and (L²AlEt)₂ (2) in reasonable isolated yields. X-ray diffraction revealed that complexes 1 and 2 have solvent-free centrosymmetric dimeric structures, and each aluminum center has distorted trigonal bipyramidal geometry. At room temperature, complexes 1 and 2 exhibit blue photoluminescence in acetonitrile with maximum emission wavelengths of 419 and 413 nm, respectively.