Root and xylem ABA changes in response to soil drying in two woody plants

Two woody plants, Platycladus orientalise (tolerant to drought) and Acacia auriculi-formis (sensitive to drought), have been subjected to rapid and slow soil drying. ABA levels in their roots and xylem sap have been determined using radioimmunoassay (RIA, sensitivity is 0.4 pmol per assay vial) with a monoclonal antibody against ( + )-ABA. ABA contents of P. orientalise and A. auriculiformis growing in well watered soil are 0.3 and 2.5 nmol·gDW-1 in roots and 1.6 and 0.4 μmol in xylem saps, respectively. A rapid soil drying has been applied to these two plants with soil water content (SWC) being reduced to 0.02 and 0.06 g·gDW-1 respectively. Under such treatment, ABA was increased by 22 times and 2 times in roots and by 7 times and 34 times in xylem saps respectively for P. orientalise and A. auriculiformis. After rewatering for 6 d, ABA in roots and xylem sap of both species returned to control levels. When a slow soil drying was applied, SWC was reduced to 0.1 and 0.13 g·gDW-1 respectively for P. orientalise and A. auriculiformis. ABA was increased by 5 times and 1.6 times in roots and by 6 times and 19 times in xylem saps respectively for these two plants. ABA in roots and xylem saps decreased to near control levels 8 d after watering. Plant leaf water potentials of both plants hardly changed at times when root and xylem ABA showed substantial increase in response to soil drying. It is concluded that ABA levels in the roots and xylem saps of P. orientalise and A. auriculiformis are more sensitively regulated than leaf water potential in response to soil drying and can act as a chemical signal in root-shoot communications of the drought stress.     

Synthesis of layered LiMnO2 byin situ oxidation-intercalation and a study of the reaction mechanism and electrochemical performance

Using Mn(OH)₂ as precursor, LiOH as lithiating agent and (NH₄)₂S₂O₈ as oxidant, layeredo-LiMnO₂ was obtained by a novel method—in situ oxidation-intercalation under mild conditions (80 °C). The product was characterized by XRD, ICP, TEM and⁷Li-NMR. The results reveal that orthorhombic LiMnO₂ with high purity and good crystallinity can be obtained by this method. During electrochemical tests, a LiMnO₂/Li cell shows an initial reversible capacity of 208 mAh · g⁻¹ and a reversible capacity of 180 mAh · g⁻¹ after 30 cycles at room temperature.     

Effect of KBr on the micellar properties of CTAB

The effect of KBr on the size, shape and microviscosity of CTAB micelles has been investigated by means of laser light scattering (LLS),¹H NMR measurements and fluorescence probe. The data obtained from the various techniques are quantitatively in agreement. The R_h of micelles in 0.01 rnol · L⁻¹ CTAB solution increases from 3.5 nm to 43 nm andR _g increases to 89 nm with addition of KBr salt. In this process, both the microviscosity and molecular weight of micelles M_w have noticeable increases, too. The rod-like micelles are formed at 0.1 rnol · L¹ KBr and the worm-like micelles are formed at above 0.2 rnol · L^-1 KBr.     

生物脱毒改善蔗渣水解物木糖醇发酵性能的研究

为提高热带假丝酵母Candida troplicalis 1-18代谢产物木糖醇的产量,本研究以蔗渣半纤维素稀酸水解物作为研究材料,以生物脱毒菌株东方伊萨酵母Issatchenkia orientalis S-7细胞干重、水解物在280 nm处紫外吸收物含量、木糖醇产量作为评价指标,考察尿素、pH值、脱毒时间、预浓缩比例和细胞循环利用等5个因素对蔗渣半纤维素稀酸水解物木糖醇发酵性能的影响。结果表明,蔗渣半纤维素稀酸水解物采用Ca（OH）₂调节pH值为5,预浓缩至1/2体积,添加2 g·L^-1尿素,东方伊萨酵母S-7生物脱毒40 h,脱毒后水解物预浓缩至木糖浓度为150 g·L^-1时,热带假丝酵母1-18发酵的木糖醇产量最高,达134.5 g·L^-1,比对照组高出70 g·L^-1;循环利用细胞进行生物脱毒,脱毒时间缩短13 h;循环利用热带假丝酵母1-18对生物脱毒水解物进行产醇发酵,木糖醇产量达163.8 g·L^-1,生成速率为5.85 g·L^-1·h^-1,比第一代发酵（1.95 g·L^-1·h^-1）提高2倍。生物脱毒是改善木质纤维稀酸水解物木糖醇发酵性能的有效手段。     

Description of mechanism function about dehydration of cobalt oxalate dihydrate by multiple rates isotemperature method

0　IntroductionThetechnologyofthermalanalysishasbeenwidelyusedinthestudyofthermalbehaviorandthermalcharacterofsolidstatereaction ,theprimaryintentionofthermalanalysiskineticsistoestablishseparatevaluesofapparentactivationenergyE ,themostprobablemechanism g(α)andthepre exponentialfactorA ,meanwhilethedeterminationofg(α)hasgraduallybeenthefocusofthisfield .Inthisfield ,therearemostlygeneralkineticsmethodsused presently ,suchasCoats Redfern’s[1 ] integralmethod ,Achar’s[2 \〗differentialmet…     

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.     

去除和添加凋落物对马尾松×红锥混交林土壤呼吸的影响

为探讨凋落物输入量改变对马尾松×红锥混交林碳排放的影响,以马尾松×红锥异龄混交林为研究对象,通过添加和去除凋落物人为地改变碳输入,研究凋落物处理方式对土壤呼吸的影响。结果表明:(1)去除凋落物可降低土壤湿度、提高土壤温度,而添加凋落物则提高土壤湿度、降低土壤温度。去除凋落物使土壤年均呼吸速率显著降低27.88%,而添加凋落物则使土壤年均呼吸速率显著增加34.02%。(2)去除凋落物能降低四季的土壤呼吸累积排放量,而添加凋落物则提高四季的土壤呼吸累积排放量。对照、去除和添加凋落物的土壤呼吸的年累积排放量(以C计)分别为(9.51±0.12) t·hm~(-2)、(6.88±0.21) t·hm~(-2)和(12.70±0.53) t·hm~(-2),可见去除凋落物使土壤呼吸年累积排放量降低27.66%,而添加凋落物使土壤呼吸年累积排放量提高33.54%。(3)不同凋落物处理方式下土壤呼吸速率与土壤温度均呈显著相关,土壤温度解释了土壤呼吸速率变异程度的74.26%～94.28%。去除凋落物增加了土壤呼吸温度敏感性系数Q10值,而添加凋落物则降低Q10值。凋落物处理方式对马尾松×红锥异龄混交林土壤呼吸产生了显著影响,证明凋落物对于改变森林生态系统土壤呼吸和碳循环具有重要作用。     

Estimation of soil respiration in a paddy ecosystem in the subtropical resion of China

Water vapor, energy exchange, and CO2 flux were measured continuously from 2003 to 2005 using the eddy covariance technique in a paddy ecosystem in the subtropical region of China. The CO2 fluxes at nighttime during fallow periods （from middle October to late April） were used to analyze the dynamics of soil respiration and its relationship with soil temperature, and to simulate the annual dynamics of soil respiration in paddy ecosystems. The variation of soil respiration showed a clear seasonal pattern. The soil respiration rates at night during the fallow periods were 52--398 mg· m^-2· h^-1, and exponentially correlated （P〈0.001） with soil temperatures at different depths of soil （5, 10, and 20 cm）, particularly the temperature measured at a depth of 5 cm. Based on the simulated exponential equations developed, annual average soil respiration rates and total soil respiration of paddy soil in the subtropical region of China were estimated to be 178.5--259.9 mg· m^-2· h^-1 and 1.56--2.28 kg· m^-2· a^-1, respectively. The simulation equations can be applied to evaluating soil respiration in paddy ecosystems during the rice-growing season.     

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)。     

人工栽培金银花的生物量和元素含量测定及其经济效益估算

采集广西忻城县红渡镇金银花(Lonicera quaponica)种植示范区人工栽培3年生的金银花样品,测定生物量及各器官的主要元素含量,并估算金银花的经济效益.结果表明,金银花的生物生产力是藤茎(0.79t·hm-2·a-1)＞叶子(0.40t·hm-2·a-1)＞根(0.33 t·hm-2·a-1)＞花(0.30 t·hm-2·a-1);金银花的主要元素(N、P、K)平均含量显示花(5.68 kg·hm-2)＞叶子(4.60kg·hm-2)＞藤茎(3.06kg·hm-2)＞根(2.93 t·hm-2);金银花年均产干花1.78 t·hm-2,年均经济收入每公顷35600元.     

A Note on the Prime Spectrums of Character Rings of Finite Groups

0Introduction LetGbeafinitegroupoforder|G|=g,andletR(G)denotethecharacterringofG,whichisgeneratedbyalltheirreduciblecomplexcharactersofG.LetZbetherationalintegerringandNthesetofnatural numbers,andletZ[ω]betheintegralextensiongeneratedbyaprimitiveg throotωofunity.SupposethatSisasubringof thealgebraicnumberfieldsuchthatZ[ω]S.πisasetofra tionalprimenumbersdefinedasfollowsπ={p｜pisarationalprimenumbersuchthatp-1S}.Definition1WecallthataconjugacyclassCofthefinite groupGisaπregularconju…     

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。     

Fluorescence Determination of Artemisinin Using Hemoglobin as Catalyst and Pyronine B as Substrate

0 IntroductionMaalnadria siusb atr ompajicosr .he aAltrthe pmrisoibnlienmi (n qtihneghtraoopsiucs,QHS,Fig.1) is a sesquiterpene endoperoxide isola-ted fromArtemisia annuaL., an ancient Chineseherbal medicine usedfor treatment of fever and ma-laria.Studies of the structure and activity relation-ship have shownthat endoperoxide groupis essentialfor anti malarial activity of QHS and absence of thismoiety lead to completely loss in activity of thedrug. Many techniques have been developed to de…     

Modes of occurrence of arsenic in high-arsenic coal by extended X-ray absorption fine structure spectroscopy

The concentration ranges of As and Sb in six Late Permian high-arsenic coals collected from Xingren and Xingyi, Guizhou Province are 94.1 μg·g -1-3 2 and 8 1 μg·g -1-120 μg·g -1, respectively. Based on the mineralogical analysis, no arsenic and arsenic-bearing minerals are detected in these samples and arsenic occurs in coal macerals. By extended X-ray absorption fine structure(EXAFS) spectroscopy, we have found that arsenic in these high-arsenic coal samples coordinates with oxygen; the coordination number of As with oxygen for these samples is 4 except one sample(H-9) for which the coordination number of As is 3. Therefore, arsenic in these high-arsenic coals does not occur in sulfide minerals, but occurs in arsenate or arsenite phase, and the preponderance of As is in arsenate of As 5+.     

Synthesis, Characterization and Properties of LiFePO4/C Cathode Material

Lithium iron phosphate coated with carbon (LiFePO₄/C) was synthesized by improved solid-state reaction using comparatively lower temperature and fewer sintering time. The carbon came from citric acid, which acted as a new carbon source. It was characterized by thermogravimetry and differential thermal analysis (TG/DTA), X ray diffractometer (XRD), Element Analysis (EA) and Scanning electron microscope (SEM). We also studied the electrochemical properties of the material. The first discharge capacity of the LiFePO₄/C is 121 mAh·g⁻¹ at 10 mA·g⁻¹, at room temperature. When the current density increased to 100 mA·g⁻¹, the first discharge capacity decreased to 110 mAh·g⁻¹ and retained 95% of the initial capacity after 100 cycles. The LiFePO₄/C obtained shows a good electrochemical capacity and cycle ability at a large current density. Foundation item: Supported by the National Natural Science Foundation of China (20071026) Biography: ZHOU Xin-wen (1980-), male, Master, research direction: inorganic material chemistry.     

金钗石斛试管苗生根研究

在基本培养基MS上分别添加不同浓度和配比的α-奈乙酸(NAA)和6-苄氨基嘌呤(6-BA)、吲哚丁酸(IBA)和6-BA,不同浓度的多效唑(PP333);在MS 6-BA 0.2mg·L-1 NAA 1.0mg·L-1 活性炭0.1%培养基上分别添加10%的香蕉汁、马铃薯汁、椰子汁、番茄汁和胡萝卜汁5种天然成分对金钗石斛(Dendrobium nobile)试管苗进行生根研究.结果表明:NAA和IBA分别与6-BA配合使用均能抑制试管苗根的分化及生长,但单独使用对促进试管苗根的分化及生长有显著的效果,NAA的浓度为0.5～1.0 mg·L-1时,试管苗生根效果较佳,当IBA浓度为0.2mg·L-1时,试管苗生根率达100%,且根数多而粗壮,NAA和IBA均可单独作为促进金钗石斛试管苗生根培养的理想的植物激素;PP333 2～4 mg·L-1可促进再生植株根的形成,但抑制根的伸长生长,建议与其他激素配合使用;5种天然成分均对试管苗根的分化、长度和粗壮度有明显的促进作用,其中附加10%香蕉汁对试管苗的生根效果最好.     

Studies on reduced extent method for inhibited thermokinetics of enzyme-catalyzed reaction

The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distinguishing inhibition type was given and the methods for calculating kinetic parameters,K _M,K _i andv _m were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation ofo-dihydroxybenzene bym-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type,K _M=6.224×10⁻³ mol·L⁻¹,K _i=2.363×10⁻² mol·L⁻¹. Xiong Ya: born Sep. 1961, Ph. D. graduate student. Curent research interest is in biothermochemistry research Supported by the National Natural Science Foundation of China     

Distribution characteristics of soil organic carbon of alpine meadow in the Eastern Qinghai-Tibet Plateau

A study on the distribution characteristics of soil organic carbon (SOC) in the alpine meadow in the Eastern Qinghai-Tibet Plateau has been carried out. The results indicate that the content of soil organic carbon (C _SOC) in the topsoil of terrace meadow (TM) ((67.16 ± 1.02) g·kg⁻¹) is more than that in the soil of upland meadow (UM) ((63.42 ± 0.65) g·kg⁻¹), while the C _SOC in upland shrubland (US) ((67.49 ± 0.83) g·kg⁻¹) is the most abundant in the scoreh stage (September). From May to September, the C _SOC in the topsoil of UM and US tends to descend, but that of TM tends to ascend. As for the distribution of the C _SOC and the density of SOC in the soil in the three sample areas, the data show that the deeper the soil, the lesser the content and density of SOC. The C _SOC in US is higher than that in TM and UM; the C _SOC in UM is the lowest at 0–10 cm soil depth. The density of SOC in US is always the lowest among UM, TM, and US at 0–40 cm depth, which shows that the storage of carbon in UM is more than that in US in the same range; the carbon pool capacity in UM is higher than that in US in the same range. Biography: ZHANG Wei (1979–), male, Lecturer, research direction: ecology of environment.     

Validating a dust production model by field experiment in Mu Us Desert, China

It is essential for validation and improvement of a dust production model to perform field observations on dust emissions. The dust production model (DPM model) consists of two physically explicit sub-models, namely saltation model [1, 2] (eq. (1)) and sandblasting model [3] (eqs. (2) and (3)). Fh is saltation flux, E is fraction of erodible surface, C is a dimensional constant, ρa is air density, g is gravitational acceleration, U* is the wind friction velocity, Ut*(Dp) is threshold frict…     

Formate and acetate as recorded in a mid－latitude glacier in west China

Formic (HCOOH) and acetic (CH3COOH) acids are the chief carboxylic compounds in the troposphere[1]. Although weak acids, they contribute significantly to the free acidity, ionic balance of precipitation and the chemical reactions in the atmosphere, especially in the remote areas[2—4]. General sources for formate and acetate have been identified in the past 3 decades although a satisfactory source attribution is lacking to explain atmospheric observations[5]. Possible sources include veget…