Thymidine kinase gene mutation leads to reduced virulence of pseudorabies virus

To explore correlation between the tk gene structure of pseudorabies virus (PRV) and its virulence, to study the effect of the gene mutation on PRV biological properties, and to investigate mechinism of reduced virulence, thymidine kinase (TK)-deficient mutant of pseudorabies virus strain Hubei (PRV HB) was isolated by selection for resistance to 5-bromodeoxyuridine. The tk genes of PRV HB and its TK^― mutant were cloned and sequenced. 1587 base pairs of the tk gene and flanking regions of wild-type (wt) virus were sequenced, which included an open reading frame (ORF) of 1098 bp encoding a protein of 366 amino acids. The ORF contained two 137-bp repeated sequences, which were connected by an adenosine. 1458 bp of the tk and flanking regions of TK^― mutant were sequenced. Analysis of the tk gene sequence of TK^― mutant indicated that one of 137 bp repeated sequence and the connecting adenosine in the tk gene of the wt virus was deleted and a repeated sequence of 8 nucleotides (GCGCGCC) was inserted. All other nucleotides of TK^―mutant were identical to that of wt virus. Deletion and insertion of the nucleotide sequence resulted in a frameshift and a premature chain termination, and the resultant TK protein was not active. Analysis of the amino acid sequence revealed that TK protein of PRV HB contained the conserved consensus sequence of herpesviral TKs and an additional conserved-DHR-motif. The results of this work also indicated that TK^― mutant was genetically stable. Compared to PRV HB, virulence of TK^― mutant was greatly decreased. Mice vaccinated with TK^― mutant were completely protected against a lethal challenge with virulent PRV (HB).     

Fabrication of MgB2 superconducting films by different methods

MgB₂ superconducting films have been successfully fabricated on single crystal MgO(111) and c-AL₂O₃ substrates by different methods. The film deposited by pulsed laser deposition is c-axis oriented with zero resistance transition temperature of 38.4 K, while the other two films fabricated by chemical vapor deposition and electrophoresis are c-axis textured with the zero resistance transition temperature of 38 K and 39 K, respectively. Magnetization hysteresis measurements yield critical current density J_c of 10⁷ A/cm² at 15 K in zero field for the thin film and of 10⁵ A/cm² for the thick film. For the thin film deposited by chemical vapor deposition, the microwave surface resistance at 10 K is found to be as low as 100 μΩ, which is comparable with that of a high-quality high-temperature superconducting thin film of YBCO.     

Fabrication of MgB2 superconducting films by different methods

MgB₂ superconducting films have been successfully fabricated on single crystal MgO(111) and c-AL₂O₃ substrates by different methods. The film deposited by pulsed laser deposition is c-axis oriented with zero resistance transition temperature of 38.4 K, while the other two films fabricated by chemical vapor deposition and electrophoresis are c-axis textured with the zero resistance transition temperature of 38 K and 39 K, respectively. Magnetization hysteresis measurements yield critical current density J_c of 10⁷ A/cm² at 15 K in zero field for the thin film and of 10⁵ A/cm² for the thick film. For the thin film deposited by chemical vapor deposition, the microwave surface resistance at 10 K is found to be as low as 100 μΩ, which is comparable with that of a high-quality high-temperature superconducting thin film of YBCO.     

Effects of electrolysis on Microcystis aeruginosa in water

Microcystis aeruginosa (blue-green algae) is of concern in relation to drinking water because of its ability to produce toxins and odors that can significantly impair water quality. The drinking water contaminated with toxic cyanobacteria could cause the death of the domestic and wild animals and the cases of human illness. To minimize the threat, the treatment of eutrophicated water containing algae (M.aeroginosa) was conducted via electrochemical oxidation process, with titanium based anode coated with RuO₂ in this study. The research showed that the electrochemical oxidation process was effective in inhibiting the growth of the algae such as M.aeruginosa. The electrolysis parameters such as: electrolysis time, current density, and electrodes distance were analyzed by the orthogonal collocation method. The results showed the electrolysis time was the dominant factor for the inhibition of the algal growth. The optimal operating conditions were: current density of 10 mA/cm² and the electrodes distance of 6 cm. The inhibitive efficiency was 92.64% with the electrolysis time of 40 minutes. The preliminary mechanism of this process was also explored and proposed in this paper.     

The modified method of upwind with finite difference fractional steps procedure for the numerical simulation and analysis of seawater intrusion

Numerical simulation and analysis of seawater intrusion is the mathematical basis for modern environmental science. Its mathematical model is the nonlinear coupled system of partial differential equations with initial-boundary problems. For a generic case of a three-dimensional bounded region, the modified method of upwind with finite difference fractional steps procedure is put forward. Optimal order estimates in L² norm are derived for the error in the approximation solution. The present method has been successfully used in predicting the consequences of seawater intrusion and protection projects.     

Pu(H2O)53+和Pu(H2O)54+ 团簇的相对论密度泛函研究

用TPSSTPSS密度泛函方法, Pu离子和H₂O分子分别采用相对论有效原子实势(RECP)和6-31g基组, 研究了Pu(H₂O)₅³⁺和Pu(H₂O)₅⁴⁺ 团簇溶剂化和非溶剂化效应中的几何结构及紫外可见吸收光谱. 计算结果表明: 水溶剂环境对Pu(H₂O)₅³⁺及Pu(H₂O)₅⁴⁺ 团簇的几何结构影响都比较明显. NBO电荷分析表明水分子与钚离子之间没有直接的电荷转移. 所研究团簇的未配对电子都占据5f轨道. 在气相及水溶剂环境下, 所研究团簇的紫外可见吸收光谱存在较大差距. 主要的吸收峰大都源于f电子之间的跃迁.     

高温变形时Al67Mn8Ti25的动态回复和动态再结晶

The deformation microstructure of Ll₂-structure Al₆₇Mn₈Ti₂₅ compound after tension at high temperature was investigated by TEM. The results show that dynamic recovery occurs and there exist a high density of dislocations, dislocation walls and unstable networks within the grains after deformation at 1 173 K and a strain rate of 8.35×10^-5 s^-1. At 1 173 K and a strain rate of 3.34×10^-5s^-1, dynamic recrystallization took place and the deformation microstructures were fine recrystallized grains with stable sub-boundaries in the specimen. Owing to difficulties in the dislocation motion and the process concerned with atom diffusion, the dynamic recovery and dynamic recrystallization occur only at rather higher temperature and lower strain rates, and only under this condition can the appreciate tensile ductility be obtained for this compound.     

ZnGa2Se4:V3+ 光谱的理论研究

应用区分t₂和e轨道共价性的差异(包含静电部分和晶场部分)并考虑了低对称场的能量矩阵, 在考虑和忽略静电参量B₀₀的条件下, 分别研究了t₂和e轨道共价性的差异对三元半导体ZnGa₂Se₄:V ³⁺能级以及低对称分裂的影响; 计算了ZnGa₂Se₄:V ³⁺晶体的能级的低对称分裂, 并与实验值进行比较. 计算结果与实验值符合很好. 研究发现: 在对ZnGa₂Se₄:V ³⁺晶体的光学性质进行理论研究时, 在能量矩阵的静电和晶场部分同时考虑t₂和e轨道共价性的差异是非常有必要的; 晶场参量B₀₀对ZnGa₂Se₂4:V ³⁺的能级有重要影响, 因此不能忽略.     

Mechanism of electrochemical evolution of chlorine and oxygen at Ti/SnO2-IrO2 anode

The mechanisms of chlorine and oxygen electrochemical evolution at a novel Ti/SnO₂-IrO₂ anode were investigated using cyclic voltammetry and steady state current?potential measurements. For this study a laboratory constructed model cell was employed. Firstly, controlled potential electrolysis of 0.1 mol/L NaCl was performed and chlorine was observed to evolve at potential +1.2 V. The pH values of the solution decreased during electrolysis over the potential range of +1.0 V?+2.0 V, suggesting that oxygen evolution may involve in the reactions. Electrolysis with a de?oxygenated NaCl solution at a fixed potential of +2.0 V confirmed that O2 is one of the products generated at the anode. Further electrolysis of NaCl solution was conducted under steady state conditions. A potential?current density plot was constructed over the potential range of +1.00 V?+1.28 V. The slope of the plot at Tafel section was found to be 41 mV/decade. These results indicate that chlorine evolution at the anode is achieved via an intermediate layer formed by electrosorption of oxygen and chlorine on the electrode surface.     

Global inventory of Helium-3 in lunar regoliths estimated by a multi-channel microwave radiometer on the Chang-E 1 lunar satellite

Helium-3 (³He) implanted by solar wind in the lunar regolith is a valuable resource because of its potential as a fusion fuel. On the basis of the Apollo regolith samples, a linear relationship between ³He abundance and solar wind flux, optical maturity and TiO₂ content has been presented. China successfully launched its first lunar exploration satellite Chang-E 1 (CE-1) on October 24, 2007. A multi-channeled microwave radiometer was aboard the satellite with the purpose of measuring microwave thermal emission from the lunar surface layer. From the multi-channel brightness temperature (T_b) observed by CE-1, the global distribution of the regolith thickness was inverted from the multi-channel T_b, and was used to evaluate the total amount of ³He per unit area in the lunar regolith. The global inventory of ³He was estimated as being 6.6×10⁸ kg; 3.7×10⁸ kg for the lunar nearside and 2.9×10⁸ kg for the lunar farside.     

Export and remineralization of POM in the Southern Ocean and the South China Sea estimated from 210Po/210Pb disequilibria

Disequilibria between ^210Po and ^210Pb in the upper water and their potential applications as a proxy of particle export and remineralization were examined in the Southern Ocean （station IV3） and the South China Sea （NS44）. ^210po was deficit in surface waters but excessive relative to ^210Pb in subsurface waters. Good positive correlation between ^210Po and particulate organic carbon （POC） indicated deficits and excess of ^210Po resulted from particulate organic matter （POM） export and remJneralization respectively, which was also supported by the decreased δ^13C and increased δ^15N downwards as a result of particle remineralization. On the basis of ^210Po/^210Pb box-model, POC export flux out of the surface waters were 1.2 mmol C. m^-2. d^-1 and 2.3 mmol C. m^-2. d^-1 for station NS44 and IV3, respectively. In the subsurface waters, remineralization fluxes of ^210Po were 0.062 Bq. m^-2.d^-1 and 0.566 Bq.m^-2.d^-1 for station NS44 and IV3 along with the recycle efficiency of 52±26% and 119±52%, respectively. Remineralized fluxes of POM derived from ^210Po and exported POC were 0.6 mmol C.m^-2.d^-1 and 2.7 mmol C. m^-2. d^-1 for NS44 and IV3. This study suggested that ^210Po was a powerful tracer of particle export and remineralization.     

广西乐业天坑群中苔藓的放射性核素分析

为探究广西喀斯特地貌对放射性核素分布及当地环境放射性的影响,利用高纯锗探测器对广西喀斯特地区的大曹天坑和邓家坨天坑采集来的苔藓样品中⁷Be、⁴⁰K、²³⁸U、²³²Th、²²⁶Ra、²¹⁰Pb和¹³⁷Cs的放射性比活度进行测量与分析。结果表明：在苔藓植物中, ⁷Be的放射性比活度为202.3-698.8 Bq/kg [平均值：(430.7±169.7) Bq/kg,n=7];⁴⁰K为33.7-159.9 Bq/kg [平均值：(91.6±44.1) Bq/kg, n=7];²³⁸U为检测限(3.0 Bq/kg)至54.4 Bq/kg [平均值：(16.9±23.6) Bq/kg,n=7];²³²Th为1.2-42.5 Bq/kg [平均值：(14.7±15.9) Bq/kg, n=7];²²⁶Ra为0.7-48.4 Bq/kg [平均值：(16.9±20.3) Bq/kg,n=7];²¹⁰Pb为284.1-950.5 Bq/kg [平均值：(555.5±231.0) Bq/kg, n=7]; ¹³⁷Cs为检测限(0.1 Bq/kg)至2.3 Bq/kg [平均值：(1.1±0.9) Bq/kg,n=7]。对比后发现所有测得的数据均在正常范围内,表明天坑这一喀斯特地貌对放射性核素的分布并没有显著影响,该地区也不存在其他污染来源,同时为我国南方喀斯特地区大气示踪提供数据支撑。     

Determination of specific activity of230Th in uranium ore samples

A new method suitable for determining specific activity of²³⁰Th in uranium ore samples is built. The method is characterized by adding the²³⁰Th/²³²Th standard dilution agent with lower activity ratio (Its²³⁰Th/²³²Th activity ratio and²³⁰Th have been known) to the samples and using isotopic dilution analysis. The method can be applied to analyses of²³⁰Th specific activity in various²³⁰Th/²³²Th activity ratio samples. The precision can also be improved.     

Impact of gamma radiation and salinity on growth and K+/Na+ balance in two populations of Medicago sativa (L.) cultivar Gabès

The perennial Medicago sativa cv. Gabès is widely grown on saline soils in Tunisian oases. Morphological and physiological analyses of two populations (Mareth and Gannouch) were conducted in order to study the effect of salinity and gamma radiation (350 Gy) interaction on two populations of this species. It has been shown that the two irradiated populations of Medicago sativa are fairly tolerant to salt at growth phase compared to the non-irradiated. Exposure to gamma irradiation (350 Gy), alone or in combination with salt stress, increased significantly (p<0.001) shoot number, stem height and chlorophyll b pigment especially for the Gannouch population, while no change occurred for the Mareth population. The presence of salt to 9g/l affected significantly the root biomass and induced a reduction of shoot development of both control and irradiated alfalfa populations. For all treatments, plants of two populations remained able to produce and to allocate dry matter to the different organs. The survey of Na⁺ / K⁺ ratio showed that the growth of the aerial organs of two non-irradiated populations was at least determined by a selectivity in favour of the K+ ions (r² = 0.97 and r² = 0.59 for Mareth and Gannouch irradiated populations, respectively). However, the rather weak correlation detected for the irradiated populations, particularly for the irradiated Gannouch, seems to be the consequence of the effect of irradiation that improved potassium availability, essential element for growth and development. Results also showed that the two irradiated populations, especially the Mareth, accumulated Na⁺ ions in its photosynthetic organs. This accumulation was associated with an improvement of foliar water content at a level of salinity arrounding 5g/l. Such a mechanism reflects probably an inclusive behaviour of the plants and a good aptitude to use the dominant ions (Na⁺) for the osmotic adjustment. However, the non-irradiated populations are unable to adjust their internal osmotic potential. Consequently, irradiated plants have probably adapted to the osmotic stress by either closing their stomata or increasing the osmotic pressure of the leaf cells.     

Mechanisms of peroxynitrite-induced [Ca2+]i increase in single neuronal cell

The mechanism of peroxynitrite (ONOO⁻)-induced [ca²⁺]_i increase in single MN9D cell (Dopaminergic neuroblastoma cell line) was studied by using Fura-2 microfluorometric technique. The results show that ONOO⁻ caused a rapid increase of [Ca²⁺]_i when ONOO₋ was puffed to the cell. Removing Ca²⁺ from the bath or using calcium channel antagonist (CdCl₂, Nifedipine) greatly inhibited the [Ca²⁺]_i increase induced by ONOO⁻¹, suggesting that the opening of L-Ca²⁺ channel makes a great contribution to the [Ca²⁺]_i increase. The effect of sulfhydryl reductive agent (DTT) on ONOO⁻-induced [Ca²⁺]_i increase suggests that ONOO⁻-activating L-Ca²⁺ channel is partly related to its oxidative speciality.     

Effect of fatty acids on polyamine contents and Na+/H+ antiport activity in PM vesicles isolated from roots of barley under salt stress

With 200 mmol/L NaCl treatment on barley cultivar “Jian 4” (Hordeum vulgare L. cv. J4) seedlings for 6 d, the contents of covalently and noncovalently conjugated polyamines (PAs) and activities of H⁺-ATPase in plasma membrane (PM) vesicles isolated from the roots decreased remarkably. Moreover, the activity of Na⁺/H⁺ antiport was detected first in PM vesicles. The results showed that the decrease in the contents of membrane phospholipid, noncovalently conjugated PAs and activity of H⁺-ATPase caused by NaCl could be restored partially by application of 1 mmol/L stearie acid (C_16:0) and linoleic acid (C_18:2), and C_18:2 was more effective than C_16:0 In addition, a reduction in the contents of covalently conjugated PAs was only reversed partially in the presence of C_18:2 Furthermore, Na⁺/H⁺ antiport activity was strengthened by exogenous C_16:0 and C_18:2 and C_18:2 was more effective than C_16:0. The correlative analysis suggested that, after application of C_16:0 and C_18:2 under salt stress, there was a significant positive correlation existing among phospholipid content, noncovalently conjugated PA levels, H⁺-ATPase activities and Na⁺/H⁺ antiport activities, indicating that one of the mitigative mechanisms of exogenous fatty acids on salt injury was to improve membrane phospholipid and PA contents, leading to an enhance in membrane integrity and a change in charge status of PM vesicles, so the activity of membrane-associated enzyme H⁺-ATPase was increased and synthesis of Na⁺/H⁺ antiport protein was activated.     

含Sr2+和Bi3+有机杂化体的合成及其光降解罗丹明B

采用溶剂热法在N,N-二甲基甲酰胺溶液中合成了不同摩尔比例的SrCl_2和Bi(NO_3)_3(分别为5%,10%,30%,50%,80%)与对苯二甲酸形成的含Sr~(2+)和Bi~(3+)有机杂化体,并在紫外可见光照射下对其进行了罗丹明B降解活性的评价.结果表明:杂化体在紫外可见光下对RhB降解活性良好,其中SrCl_2摩尔比例10%掺杂的催化剂光降解活性最佳,这归结于其在紫外区域对光有很好的吸收及光生电子和空穴能有效地分离.双金属离子能协同调节有机杂化体的光催化活性.     

The concentration quenching characteristics of 5D3-7FJ and 5D4-7FJ (J=0―6) transitions of Tb3+ in YBO3:Tb3+ phosphor

The photoluminescence quenching behaviors of ^5D3-^7Fj and ^5D4-^7Fj （J = 0—6） transitions of Tb^3＋ in YBO3：Tb under 130—290 nm excitation were systematically investigated. The results revealed that the quenching concentrations of both ^5D3-^7Fj and ^5D4-^7Fj transitions of Tb^3＋ in YBO3：Tb were mainly dependent on excitation wavelength. Particularly, the quenching concentrations of ^5D4-^7Fj transitions of Tb^3＋ under 130—290 nm excitation were correlated with excitation bands of YBO3：Tb. The quenching concentrations of ^5D3-^7Fj transitions remained at low concentration （2%） under 186—290 nm excitation and then increased gradually with energy of incoming excitation photon when excited at 130—186 nm. This dependence should be involved in their excitation mechanisms and quenching pathway in particular excitation region.[第一段]     

Research at channel level on the effect of LaCl3 on Radish (Raphanus satirus L.) vacuolar membrane

We recorded slow vacuolar (SV-type) channel currents of Radish vacuoles successfully for the first time by using the whole-vacuolar patch-clamp recording mode. SV- type currents would increase and threshold potentials of activation would shift towards more negative values with the increase of concentrations of cytosolic Ca²⁺. When 2.5 mmol/ L LaCl₃ and 4 mmol/L EGTA were added to bath solutions, SV-type currents were suppressed remarkably. Then adding LaCl₃ with different concentrations to pipette solutions, we found that LaCl₃ with higher concentrations (＞4 ´ 10^-7 mol/L) had a strong inhibitory effect on SV-type currents, while LaCl₃ with lower concentrations (≤4 ´ 10^-7 mol/L) promoted channel currents. This promoting effect provides an important basis at channel level for researching further the effects of rare earth on physiological activities of plants and the production-increase effects of rare earth fertilizers on crops.