Alkanes in fungal spores

The chlamydospores of Ustilago maydis, U. nuda, and Sphacelotheca reiliana were analyzed by gas chromatography and mass spectrometry for their hydrocarbon contents. For the first time we observed that they contain paraffinic hydrocarbons; the average contents were 42, 58, and 146 parts per million, respectively. n-Alkanes having odd numbers of carbon atoms predom-inate, with carbon-chain lengths ranging from C(14) to C(37). The major alkanes are n-C(27) in U. maydis, n-C(27) and n-C(35) in U. nuda, and n-C(29) in S. reiliana. Each type of spore carried a distinctly characteristic population of hydrocarbons.     

油料树种千年桐的SSR标记开发、遗传多样性与群体结构分析

  目的  千年桐是大戟科油桐属的一种重要的工业油料树种，较同属的油桐具有更强的抗枯萎病能力，近年来受到了广泛关注。然而，因千年桐栽培历史短及种质管理的不足，目前对其分子遗传方面的研究还非常有限。本研究旨在开发千年桐的基因组SSR标记，进而开展其种质的鉴定、遗传多样性与群体结构分析。  方法  采用RAD测序技术获得千年桐简化基因组以开发SSR标记，基于SSR标记利用分子变异分析（AMOVA）、非加权组平均法（UPGMA）聚类、主坐标（PCoA）与群体结构分析等方法对来自3个不同地理分布的共105份千年桐种质资源进行研究。  结果  17个多态性的三核苷酸基因组SSR标记被开发，并能够很好地鉴别所有收集的105份千年桐种质。在其中62份种质中检测到85个私有等位基因，涉及15个SSR位点。AMOVA分析发现，千年桐群体间呈现出中等程度的遗传分化，但群体内的遗传变异远高于群体间的遗传变异。群体结构分析显示，3个来自不同地理分布的千年桐群体中存在4个不同的基因库，群体间既有进化独立性，又有较高程度的遗传混合，这一结果与UPGMA和PCoA分析的结果基本一致。  结论  新开发的17个SSR标记有效鉴定了105份千年桐种质，揭示了其遗传多样性和群体遗传结构，对千年桐种质保存和育种计划具有非常重要的参考价值。      

能源微藻——葡萄藻培养的研究进展

葡萄藻是一种世界广布的高产烃能源微藻。在石油资源日趋紧张以及环境恶化日趋严重的今天,利用该藻生产石油替代品的研究受到广泛的关注。简要概述了葡萄藻人工培养方面的研究进展,讨论了未来葡萄藻产烃工业化发展的方向。     

千年桐生态林近自然经营对土壤理化性质的影响

在按照近自然经营的原则及措施进行抚育管理和常规经营的千年桐生态林中分别选取3块样地,分析其土样理化性质．结果表明：经过近自然经营后的千年桐生态林土壤的含水量,氮磷钾、有机质含量均高于常规经营的千年桐林;土壤容重、比重和碳氮比则小于常规经营的千年桐林．由此可见,千年桐生态林的近自然经营可有效改善土壤理化状况,提高土壤肥力．     

Visualization of Surfactants on Nanostructured Palladium Clusters by a Combination of STM and High-Resolution TEM

Scanning tunneling microscopy (STM) and high-resolution transmission electron microscopy (TEM) have been used to determine the dimensions of a series of palladium clusters stabilized by tetraalkylammonium salts. Electrochemically prepared colloids were used in which the average diameter of the inner metal core was varied between 2 and 4 nanometers, and the size of the ammonium ions was adjusted in the series (+)N(n-C(4)H(9))(4) < (+)N(n-C(8)H(17))(4) < (+)N(n-C(18)H(37))(4). The difference between the mean diameter determined by STM and that measured by TEM allows the determination of the thickness of the protective surfactant layer. On the basis of these studies, a model of the geometric properties of ammonium-stabilized palladium clusters has been proposed. Suggestions for the mechanism of the STM imaging process are also made.     

千年桐苗木营养诊断研究

为科学地制定施肥措施,全面改善千年桐幼林的营养状态,使主要养分元素N、P、K达到理想的平衡状态,采用单形格子设计,应用诊断施肥综合法（DRIS）对千年桐苗木N、P、K 3种元素进行营养诊断,结果表明：苗木养分含量适宜的P/N为06922、N/K为09369、K/P为1.5419;处理E7为较理想的施肥方案,即氮肥（尿素）126g/株,磷肥（过磷酸钙）236g/株,钾肥（硫酸钾）138g/株。     

Abiogenic hydrocarbon production at lost city hydrothermal field

Low-molecular-weight hydrocarbons in natural hydrothermal fluids have been attributed to abiogenic production by Fischer-Tropsch type (FTT) reactions, although clear evidence for such a process has been elusive. Here, we present concentration, and stable and radiocarbon isotope, data from hydrocarbons dissolved in hydrogen-rich fluids venting at the ultramafic-hosted Lost City Hydrothermal Field. A distinct "inverse" trend in the stable carbon and hydrogen isotopic composition of C1 to C4 hydrocarbons is compatible with FTT genesis. Radiocarbon evidence rules out seawater bicarbonate as the carbon source for FTT reactions, suggesting that a mantle-derived inorganic carbon source is leached from the host rocks. Our findings illustrate that the abiotic synthesis of hydrocarbons in nature may occur in the presence of ultramafic rocks, water, and moderate amounts of heat.     

Petroleum associated with polymetallic sulfide in sediment from gorda ridge

A sediment sample, impregnated with asphaltic petroleum and polymetallic sulfide, was dredged from the southern end of Gorda Ridge (the Escanaba Trough) off northern California, within the offshore Exclusive Economic Zone of the United States. The molecular distributions of hydrocarbons in this petroleum show that it was probably derived from terrestrial organic matter in turbidite sediment filling the Escanaba Trough. Hydrothermal activity at the Gorda Ridge spreading center provided the heat for petroleum formation and was the source of fluids for sulfide mineralization.     

千年桐不同构件的热值分析

以3年生千年桐(Aleurites montana)林分为研究对象,采用环境恒温式氧弹量热计,对千年桐不同构件的热值进行测定。结果表明,千年桐的根、干、枝、叶、种干质量热值分别为14 264.91、16 792.21、17 170.42、23 360.99、15 710.24 J.g-1,树叶热值最高,树枝次之,各器官干质量热值由高到低依次为叶>枝>干>种>根,并存在极显著差异。千年桐的生物量加权平均干质量热值为16 298.88 J.g-1。研究结果可为千年桐能源林的规划和生物能源转化工程提供基础性的参考数据,也为千年桐的能量特征和生态效率的研究提供科学依据。     

Generation and migration of light hydrocarbons

Light hydrocarbons (containing from 1 to 14 carbon atoms) are formed from disseminated organic matter in sediments at the parts-per-billion level by biological and low-temperature (< 50 degrees C) chemical reactions and at the parts-permillion level by high-temperature (> 50 degrees C) cracking reactions. The cooler reactions produce mainly branched hydrocarbons, whereas the hotter reactions yield more straight chains. Hydrocarbon generation zones in the subsurface can be recognized on the basis of hydrocarbon distribution patterns. Hydrocarbons with tertiary carbon atoms form at lower temperatures than those with quaternary carbons. Methane and ethane migrate vertically through fine-grained shales by diffusion and solution, whereas many of the C(3+) hydrocarbons show little or no vertical migration. Concentrations of light hydrocarbons, including methane, in fine-grained source rocks decrease to low values in deep, high-temperature (>200 degrees C) sediments. This decrease may be one reason why no economic accumulation of gas has been found to date deeper than 8.2 kilometers (27,000 feet).     

千年桐花粉萌发条件筛选及储存研究

[目的]为千年桐花粉萌发及储存提供理论依据。[方法]采用单因素随机试验设计,探讨蔗糖浓度、硼酸浓度、CaCl2以及pH对花粉萌发率的影响,设计4种花粉储存的方法,研究不同方法的储存效果。[结果]在花粉萌发培养基里添加15%～20%的蔗糖、20～30mg/L的硼酸及0.05%～0.10%的CaCl2,并把pH调整到6.0～6.5有利于千年桐花粉萌发;-20℃冷冻干燥贮藏是较好的储存方法,保存10 d后的萌发率仍有25.36%。[结论]该试验解决了千年桐花粉离体萌发和储存的关键问题,具有一定的现实意义。     

Why is climate sensitivity so unpredictable?

Uncertainties in projections of future climate change have not lessened substantially in past decades. Both models and observations yield broad probability distributions for long-term increases in global mean temperature expected from the doubling of atmospheric carbon dioxide, with small but finite probabilities of very large increases. We show that the shape of these probability distributions is an inevitable and general consequence of the nature of the climate system, and we derive a simple analytic form for the shape that fits recent published distributions very well. We show that the breadth of the distribution and, in particular, the probability of large temperature increases are relatively insensitive to decreases in uncertainties associated with the underlying climate processes.     

生态公益林更新和补植树种——千年桐

系统分析了发展千年桐的重要意义,论述了千年桐的生物学特性及其用途,并阐述了千年桐的栽培技术,包括选用良种、壮苗培育、造林与抚育、病虫害防治等营林措施,为生态公益林树种的更新与补植提供参考与借鉴。     

Carbon isotope composition of carbonaceous matter from the precambrian of the witwatersrand system

Polymerized hydrocarbons occurring in the gold-uranium conglomerates of the Witwatersrand System (South Africa) show deltaC(13) values between -22.4 and -32.8 per mille, their isotopic composition thus falling into the range of sedimentary organic carbon. Accordingly, organic derivation of the material seems very probable. This conclusion is consistent with a model of the existence of organic evolution and biologic activity in times certainly older than 2.15 x 10(9) years.     

枯草芽孢杆菌对多环芳烃的降解能力研究

从长期受多环芳烃污染的土壤中分离出1株菲降解菌——菌Ⅱ,经生理生化及16S rDNA分析鉴定,该菌株为枯草芽孢杆菌。在单基质菲、芘反应体系中,该菌株具有较强的降解能力。菌Ⅱ不但可以在高浓度的多环芳烃存在下生长良好而且对高浓度多环芳烃有较高的降解能力。多环芳烃与重金属Cu2+的加入对多环芳烃降解菌有很大的影响。在Cu2+浓度小于15 mg/L时,菌Ⅱ能在以多环芳烃为唯一碳源的培养基中生长良好,Cu2+浓度过高将导致菌体死亡。     

Solubility in water of normal c9 and c10, alkane hydrocarbons

A new method for equilibrating water containing alkane hydrocarbons with a gas phase and analyzing the gas for hydrocarbon content by gas chromatography extends analytical sensitivity to better than 0.1 part per billion. The solubilities at 25 degrees C of the normal C(9) (220 parts per billion) and C(10) (52 parts per billion) alkanes decrease with increasing carbon number. A discontinuity occurs at the normal C(11), alkane, probably because of a change from true solubility (molecular dispersion) to accommodation (aggregation).     

Submarine seep of carbon dioxide in norton sound, alaska

Earlier workers have described a submarine gas seep in Norton Sound having an unusual mixture of petroleum-like, low-molecular-weight hydrocarbons. Actually, only about 0.04 percent of the seeping gas is hydrocarbons and 98 percent is carbon dioxide. The isotopic compositions of carbon dioxide (delta(13)C(PDB) = -2.7 per mil) and methane (delta(13)C(PDB) = -36 per mil, where PDB is the Peedee belemnite standard) indicate that geothermal processes are active here.     

Catalytic alkane metathesis by tandem alkane dehydrogenation-olefin metathesis

With petroleum supplies dwindling, there is increasing interest in selective methods for transforming other carbon feedstocks into hydrocarbons suitable for transportation fuel. We report the development of highly productive, well-defined, tandem catalytic systems for the metathesis of n-alkanes. Each system comprises one molecular catalyst (a "pincer"-ligated iridium complex) that effects alkane dehydrogenation and olefin hydrogenation, plus a second catalyst (molecular or solid-phase) for olefin metathesis. The systems all show complete selectivity for linear (n-alkane) product. We report one example that achieves selectivity with respect to the distribution of product molecular weights, in which n-decane is the predominant high-molecular-weight product of the metathesis of two moles of n-hexane.     

Surface-modified carbon nanotubes catalyze oxidative dehydrogenation of n-butane

Butenes and butadiene, which are useful intermediates for the synthesis of polymers and other compounds, are synthesized traditionally by oxidative dehydrogenation (ODH) of n-butane over complex metal oxides. Such catalysts require high O2/butane ratios to maintain the activity, which leads to unwanted product oxidation. We show that carbon nanotubes with modified surface functionality efficiently catalyze the oxidative dehydrogenation of n-butane to butenes, especially butadiene. For low O2/butane ratios, a high selectivity to alkenes was achieved for periods as long as 100 hours. This process is mildly catalyzed by ketonic CO groups and occurs via a combination of parallel and sequential oxidation steps. A small amount of phosphorus greatly improved the selectivity by suppressing the combustion of hydrocarbons.     

Rapid turnover of hyphae of mycorrhizal fungi determined by AMS microanalysis of 14C

Processes in the soil remain among the least well-characterized components of the carbon cycle. Arbuscular mycorrhizal (AM) fungi are ubiquitous root symbionts in many terrestrial ecosystems and account for a large fraction of photosynthate in a wide range of ecosystems; they therefore play a key role in the terrestrial carbon cycle. A large part of the fungal mycelium is outside the root (the extraradical mycelium, ERM) and, because of the dispersed growth pattern and the small diameter of the hyphae (<5 micrometers), exceptionally difficult to study quantitatively. Critically, the longevity of these fine hyphae has never been measured, although it is assumed to be short. To quantify carbon turnover in these hyphae, we exposed mycorrhizal plants to fossil ("carbon-14-dead") carbon dioxide and collected samples of ERM hyphae (up to 116 micrograms) over the following 29 days. Analyses of their carbon-14 content by accelerator mass spectrometry (AMS) showed that most ERM hyphae of AM fungi live, on average, 5 to 6 days. This high turnover rate reveals a large and rapid mycorrhizal pathway of carbon in the soil carbon cycle.