Atmospheric trace gases in antarctica

Trace gases have been measured, by electron-capture gas chromatography and gas chromatography-mass spectrometry techniques, at the South Pole (SP) in Antarctica and in the U.S. Pacific Northwest (PNW) ( approximately 45 degrees N) during January of each year from 1975 to 1980. These measurements show that the concentrations of CCl(3)F, CCl(2)F(2), and CH(3)CCl(3) have increased exponentially at substantial rates. The concentration of CCl(3)F increased at 12 percent per year at the SP and at 8 percent per year in the PNW; CCl(2)F(2) increased at about 9 percent per year at both locations, and CH(3)CCl(3) increased at 17 percent per year at the SP and 11.6 percent per year at the PNW site. There is some evidence that CCl(4) ( approximately 3 percent per year) and N(2)O (0.1 to 0.5 percent per year) may also have increased. Concentrations of nine other trace gases of importance in atmospheric chemistry are also being measured at these two locations. Results of the measurements of CHClF(2)(F-22), C(2)Cl(3)F(3)(F-113), SF(6), C(2)-hydrocarbons, and CH(3)Cl are reported here.     

Atmospheric carbon tetrafluoride: a nearly inert gas

An analysis of existing thermodynamic, photochemical, and kinetic data indicates that the dominant sinks for atmospheric carbon tetrafluoride (CF(4)) are in and above the mesosphere. Theoretical calculations predict an atmospheric residence time for CF(4) of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF(2)Cl(2)) and monofluorotrichloromethane (CFC1(3)). It is predicted that CF(4) will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 10(12) are predicted in the high stratosphere as a result of the decomposition of CF(4). Although natural sources of CF(4) cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF(4) could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers.     

Atmospheric Lifetime of CHF2Br, a Proposed Substitute for Halons

The rate coefficients, k(1), for the reaction of OH with CHF(2)Br have been measured using pulsed photolysis and discharge flow techniques at temperatures (T) between 233 and 432 K to be k(1), = (7.4 +/- 1.6) x 10(-13) exp[-(1300 +/- 100)/T] cubic centimeters per molecule per second. The ultraviolet absorption cross sections, sigma, of this molecule between 190 and 280 nanometers were measured at 296 K. The k(1), and sigma values were used in a one-dimensional model to obtain an atmospheric lifetime of approximately 7 years for CHF(2)Br. This lifetime is shorter by approximately factors of 10 and 2 than those for CF(3)Br and CF(2)ClBr, respectively. The ozone depletion potentials of the three compounds will reflect these lifetimes.     

Arctic ocean ventilation studied with a suite of anthropogenic halocarbon tracers

The chlorofluoromethanes (CFMs: CCl(2)F(2) and CCl(3)F), methyl chloroform (CH(3)CCl(3)), and carbon tetrachloride (CCl(4)) have been measured in deep waters of the Arctic Ocean. Oceanic and atmospheric inventories of these compounds result from known anthropogenic releases; because the CFMs and CCl(4) are also chemically nonreactive, they can be used as transient tracers of ocean circulation. The input history of CCl(4) is longer than that of any other transient tracer identified to date( approximately 70 years). This long input history, together with an e-folding time scale of increase(tau) of approximately 28 years, makes CCl(4) potentially the most useful tracer for calibrating models of the oceanic uptake of the fossil-fuel CO(2) transient(tau approximately 25 years). The bottom water of the Nansen Basin, Arctic Ocean, has detectable CCl(4) but undetectable CFM(s) and CH(3)CCl(3), which suggests either that the bottom water is approximately 50 years old, or that there is a small, nonanthropogenic component of atmospheric CCl(4)(<6 parts per trillion by volume).     

Atmospheric residence time of CH3Br estimated from the junge spatial variability relation

The atmospheric residence time for methyl bromide (CH3Br) has been estimated as 0.8 +/- 0.1 years from its empirical spatial variability relative to C2H6, C2Cl4, CHCl3, and CH3Cl. This evaluation of the atmospheric residence time, based on Junge's 1963 general proposal, provides an estimate for CH3Br that is independent of source and sink estimates. Methyl bromide from combined natural and anthropogenic sources furnishes about half of the bromine that enters the stratosphere, where it plays an important role in ozone destruction. This residence time is consistent with the 0.7-year value recently calculated for CH3Br from the combined strength estimates for its known significant sinks.     

Reversible, metal-free hydrogen activation

Although reversible covalent activation of molecular hydrogen (H2) is a common reaction at transition metal centers, it has proven elusive in compounds of the lighter elements. We report that the compound (C6H2Me3)2PH(C6F4)BH(C6F5)2 (Me, methyl), which we derived through an unusual reaction involving dimesitylphosphine substitution at a para carbon of tris(pentafluorophenyl) borane, cleanly loses H2 at temperatures above 100 degrees C. Preliminary kinetic studies reveal this process to be first order. Remarkably, the dehydrogenated product (C6H2Me3)2P(C6F4)B(C6F5)2 is stable and reacts with 1 atmosphere of H2 at 25 degrees C to reform the starting complex. Deuteration studies were also carried out to probe the mechanism.     

Isolation of two seven-membered ring C58 fullerene derivatives: C58F17CF3 and C58F18

Fluorination of C60 at 550 degrees C leads to milligram quantities of two stable fullerene derivatives with 58-carbon cage structures: C58F18 and C58F17CF3. The compounds were characterized by mass spectrometry and fluorine nuclear magnetic resonance spectroscopy, and the data support a heptagonal ring in the framework. The resulting strain, which has hindered past attempts to prepare these smaller quasi-fullerenes, is mitigated here by hybridization change of some of the carbons in the pentagons from sp2 to sp3 because of fluorine addition. The loss of carbon from C60 is believed to occur via sequential fluorine addition to a CC single bond and an adjacent CC bond, followed by loss of a:CF2 carbene.     

黎药光叶巴豆枝叶的化学成分分析

为研究光叶巴豆枝叶的化学成分,笔者采用硅胶柱色谱、Sephadex LH-20、半制备高效液相色谱等多种色谱技术进行化合物的分离纯化,通过化合物的波谱数据和理化性质鉴定其结构。从光叶巴豆枝叶95%乙醇提取物中分离得到12个化合物,分别鉴定为:(3S,5R,6S,7E,9R)-3,6-dihydroxy-5,6-dihydro-β-ionol ( 1 )、吐叶醇( 2 )、4,5-dihydroblumenol A ( 3 )、5-epi-eudesma-4(15)-ene-1β,6β-diol ( 4 )、aromadendrane-4β,10β-diol ( 5 )、ent-4(15)-eudesmene-1β,6α-diol ( 6 )、(7R*)-opposit-4(15)-ene-1β,7-diol ( 7 )、丁香脂素( 8 )、rel-(3R,3′S,4R,4′S)-3,3′,4,4′-tetrahydro-6,6′-dimethoxy[3,3′-bi-2H-benzopyran]-4,4′-diol ( 9 )、(+)?皮树脂醇( 10 )、thero-ficusesquilignan A ( 11 )和反式对羟基桂皮酸甲酯( 12 ),这些化合物均为首次从光叶巴豆中分离得到。采用贝尔曼漏斗法和MTT法对化合物 1 ～ 12 进行了生物活性测试,结果表明,化合物 8 ～ 12 对全齿复活线虫具有较好的致死活性,且所有化合物均无细胞毒活性。     

落叶松八齿小蠹伴生真菌富士长喙壳的防治研究

筛选落叶松八齿小蠹伴生真菌富士长喙壳(Ceratocystis fujiensis)的拮抗菌株和杀菌剂,旨在为该伴生真菌的生物防治和化学防治提供科学依据。通过22个菌株与3株富士长喙壳(CF1、CF2、CF3)的拮抗培养,筛选出相对抑制效果在3.00以上的拮抗菌:CF1有3株,CF2有8株,CF3有4株。菌株Bipolaris sorokiniana在拮抗培养中,自身的生长速率被促进,说明其拮抗效果明显。在所选用的15种杀菌剂中,10种杀菌剂对3株富士长喙壳生长抑制率大于50%,3个菌株抗药性的强弱能力为:CF3>CF2>CF1。     

Greenhouse Effects due to Man-Mad Perturbations of Trace Gases

Nitrous oxide, methane, ammonia, and a number of other trace constituents in the earth's atmosphere have infrared absorption bands in the spectral region 7 to 14 microm and contribute to the atmospheric greenhouse effect. The concentrations of these trace gases may undergo substantial changes because of man's activities. Extensive use of chemical fertilizers and combustion of fossil fuels may perturb the nitrogen cycle, leading to increases in atmospheric N(2)O, and the same perturbing processes may increase the amounts of atmospheric CH(4) and NH(3). We use a one-dimensional radiative-convective model for the atmospheric thermal structure to compute the change in the surface temperature of the earth for large assumed increases in the trace gas concentrations; doubling the N(2)O, CH(4), and NH(3) concentrations is found to cause additive increases in the surface temperature of 0.7 degrees , 0.3 degrees , and 0.1 degrees K, respectively. These systematic effects on the earth's radiation budget would have substantial climatic significance. It is therefore important that the abundances of these trace gases be accurately monitored to determine the actual trends of their concentrations.     

Atmospheric Trends and Lifetime of CH3CCI3 and Global OH Concentrations

Determination of the atmospheric concentrations and lifetime of trichloroethane (CH(3)CCI(3)) is very important in the context of global change. This halocarbon is involved in depletion of ozone, and the hydroxyl radical (OH) concentrations determined from its lifetime provide estimates of the lifetimes of most other hydrogen-containing gases involved in the ozone layer and climate. Global measurements of trichloroethane indicate rising concentrations before and declining concentrations after late 1991. The lifetime of CH(3)CCI(3) in the total atmosphere is 4.8 +/- 0.3 years, which is substantially lower than previously estimated. The deduced hydroxyl radical concentration, which measures the atmosphere's oxidizing capability, shows little change from 1978 to 1994.     

Chemical methods for removing radon and radon daughters from air

Liquid bromine trifluoride and the solid complexes ClF(2)SbF(6), BrF(2)SbF(6), BrF(4)Sb(2)F(11), IF(4)(SbF(6))(3) and BrF(2)BiF(6) react spontaneously with radon and radon daughters at 25 degrees C, converting the radioelements to nonvolatile ions and compounds. The reagents can be used in gas-scrubbing units to remove radon and radon daughters from air. The halogen fluoride-antimony pentafluoride complexes may be suitable for purifying air in uranium mines and analyzing radon in air, since they have low dissociation pressures at 25 degrees C and are less hazardous to handle than liquid halogen fluorides.     

Synthesis, structure, and reactivity of an iron(V) nitride

Despite being implicated as important intermediates, iron(V) compounds have proven very challenging to isolate and characterize. Here, we report the preparation of the iron(V) nitrido complex, [PhB((t)BuIm)(3)Fe(V)≡N]BAr(F24) (PhB((t)BuIm)(3)(-) = phenyltris(3-tert-butylimidazol-2-ylidene)borato, BAr(F24) = B(3,5-(CF(3))(2)C(6)H(3))(4)(-)), by one electron oxidation of the iron(IV) nitrido precursor. Single-crystal x-ray diffraction of the iron(V) complex reveals a four-coordinate metal ion with a terminal nitrido ligand. M??bauer and electron paramagnetic resonance spectroscopic characterization, supported by electronic structure calculations, provide evidence for a d(3) iron(V) metal center in a low spin (S = 1/2) electron configuration. Low-temperature reaction of the iron(V) nitrido complex with water under reducing conditions leads to high yields of ammonia with concomitant formation of an iron(II) species.     

在二氯甲烷溶液里〔Cu(CH_3CN)_4〕〔MF_6〕与碘化四丁铵的反应

在本实验中,研究了［Ｃｕ（ＣＨ３ＣＮ）４］［ＭＦ６］（Ｍ＝Ｍ０或Ｗ）与碘化四丁铵（Ｃ４Ｈ９）４ＮＩ在二氯甲烷（ＣＨ２Ｃｌ２）中的反应。研究结果表明,在ＣＨ２Ｃｌ２里,（Ｃ４Ｈ９）４ＮＩ未能把［Ｃｕ（ＣＨ３ＣＮ）４］［Ｍ０Ｆ６］和［Ｃｕ（ＣＨ３ＣＮ）４］［ＷＦ６］中的Ｍ０Ⅴ和ＷⅤ还原成Ｍ０Ⅳ和ＷⅣ盐。通过分析得知,反应产物是ＣｕＩ和（Ｃ４Ｈ９）４ＮＭＦ６,配位体ＣＨ３ＣＮ被解脱出来,反应中并没有产生Ｉ２。     

1株红树内生真菌Fusarium sp.代谢产物的研究

【目的】研究红树林镰刀菌属真菌Fusarium sp.R5的代谢产物。【方法】采用硅胶柱层析分离纯化代谢产物,波谱技术鉴定结构,滤纸片扩散法测试抗植物病原真菌活性。【结果】分离鉴定5-羟甲基-2-呋喃甲醛(化合物1),(3R,4R)-顺-4-羟基蜂蜜曲菌素(化合物2),(3R,4R)-顺-4,7-二羟基蜂蜜曲菌素(化合物3),Clavatol(化合物4),酒渣碱(化合物5),麦角甾-4,6,8(14),22-四烯-3酮(化合物6),β-谷甾醇(化合物7)、3β-胆甾-5-烯-3-醇(化合物8)、丁二酸和顺丁烯二酸10个化合物。在250μg·m L~(-1)时,化合物5对香蕉炭疽菌Colletotrichum musae高度抗菌,化合物5和6对番茄枯萎菌F.oxysporum、小麦赤霉菌F.graminearum中度抗菌。【结论】从Fusarium属分离得到化合物1~8,其中,化合物5、6可作为相应农药抗菌先导化合物开展深入研究。     

有机肥与化肥配施对松花菜花球营养品质和挥发性物质的影响

以松花菜品种力禾青梗100天为材料,设置CK1(不施肥)、CK2(常规施肥)、T1(平衡施肥)、T2(平衡施肥+3 000 kg·hm^-2生物有机肥)、T3(平衡施肥+6 000 kg·hm^-2生物有机肥)和T4(平衡施肥+12 000 kg·hm^-2生物有机肥)6个处理,研究不同处理对松花菜花球营养品质和挥发性物质数量与含量的影响。结果表明:相比CK2,生物有机肥配施化肥(T2~T4处理)有助于提高松花菜花球营养物质含量和挥发性物质的数量与含量。与CK2相比,T3处理下松花菜花球的维生素C含量显著(P<0.05)提高17.6%;T2和T3处理下松花菜花球中的Ca含量分别显著(P<0.05)提高14.3%和36.8%。T2、T3、T4处理下松花菜花球中的挥发性物质数量分别比CK2增加8、12、13种,酮类物质含量较CK2分别增加3.4、2.9和7.1倍。另外,与CK2相比,T2和T3处理下松花菜花球中具有青香、果香和花香味的特征性挥发性物质种类和含量增加。基于营养品质指标和挥发性物质指标的主成分分析综合评价结果显示,6个处理的得分从高到低依次为T3>T2>T4>CK2>T1>CK1。在本试验条件下,较常规施肥化肥减量30%的平衡施肥方案配施6 000 kg·hm^-2生物有机肥处理下松花菜花球的综合品质最优。     

尿素、柠檬酸对雏鸡生长发育及血液生化指标的影响

 选择1日龄尼克红蛋公雏264只,随机分为6组,每组4个重复,每个重复11只,试验期42 d. 各组添加0％,0.1％尿素、0.2％尿素、0.4％尿素、0.3％柠檬酸、0.2％尿素＋0.3％柠檬酸,研究尿素、柠檬酸及其复合物对雏鸡生长发育及血液生化指标的影响。试验结果显示:（1）添加0.1％尿素显著提高雏鸡期末体重（P＜0.05）,并趋于改善日增重、全期采食量及饲料转化率(P＞0.05)。(2)与添加0.1％尿素相比,添加0.4％尿素显著降低期末体重、日增重、采食量(P＜0.05),并趋于降低饲料转化率(P＞0.05)。(3)添加0.4％尿素,显著提高血清尿素氮含量(P＜0.05),显著降低血清总蛋白含量(P＜0.05)。添加0.2％尿素＋0.3％柠檬酸复合物显著提高血清尿素氮含量(P＜0.05),但不影响血清总蛋白含量(P＞0.05)。添加0.1％和0.2％尿素,对血清尿素氮无影响(P＞0.05),而血清总蛋白显著降低(P＜0.05)。结果表明:饲料中添加0.1％尿素对雏鸡生长具有一定的调控作用。     

Atmospheric trace gases: trends and distributions over the last decade

Concentrations of the halocrbons CCl(3)F (F-11), CCl(2)F(2) (F-12), CCl(4), and CH(3)CCl(3), methane (CH(4)), and nitrous oxide (N(2)O) over the decade between 1975 and 1985 are reported, based on measurements taken every January at the South Pole and in the Pacific Northwest. The concentrations of F-11, F-12, and CH(3)CCl(3) in both hemispheres are now more than twice their concentrations 10 years ago. However, the annual rates of increase of F-11, F-12, and CH(3)CC1(3) are now considerably slower than earlier in the decade, reflecting in part the effects of a ban on their nonessential uses. Continued increases in these trace gas concentrations may warm the earth and deplete the stratospheric ozone layer, which may cause widespread climatic changes and affect global habitability.     

滞库片烟长期存放过程中主要化学成分的变化

以已醇化3年的福建南平C3F、云南曲靖C3F、贵州黔西南C3F和C4F片烟为材料，连续5年取样，测定片烟在滞库期间常规化学成分(总植物碱、总糖、还原糖、总氮)，高级脂肪酸(亚油酸、油酸、亚麻酸、十六酸、十八酸)和多酚化合物(绿原酸、隐绿原酸、莨菪亭、芸香苷)含量，并分析其变化。结果表明：片烟的总糖、还原糖、亚麻酸、绿原酸、隐绿原酸和芸香苷含量随着滞库时间的延长呈现逐渐降低的趋势；主成分分析表明，片烟的主成分综合得分在滞库期间逐年下降，且在滞库2～3年后片烟会出现明显的品质下降；比较黔西南C3F和C4F片烟，C3F片烟在滞库4年后的综合得分开始低于滞库前的C4F片烟综合得分，说明滞库时间过长会使得片烟发生品质降级现象；比较南平、曲靖、黔西南的C3F片烟，曲靖片烟较耐贮藏，南平片烟不耐贮藏。     

生防菌对向日葵列当的防除作用的初步研究

通过室内穴盘和连续两年遮雨棚盆栽试验,研究放线菌淡紫褐链霉菌(Streptomyces enissocaesilis,509),真菌灰黄青霉(Penicillium griseofulvum,CF3)和放线菌密旋链霉菌(Streptomyces pactum,Act12)3种生防菌对寄主植物向日葵的促生作用和对向日葵列当种子萌发的抑制作用。结果表明:1)CF3和Act12处理条件下,列当的出土数和寄生总数量显著降低,在新葵6号中CF3抑制列当寄生率高达74.4%,Act12抑制列当寄生率为68.7%,509抑制列当寄生率为53.0%;2)在列当寄生胁迫下,生防菌处理向日葵相比对照生物量有显著的增高,根冠比显著增大,含水量显著升高,生防菌处理的向日葵地上部和根的含水量≥70%。本研究表明CF3和Act12具有作为防除向日葵列当优良生防菌种的可能性。