Automatic lipid extraction and thin-layer chromatography application with a prgrammed flow system

An eight-channel programmed flow system for automatic lipid extraction and TLC application is described. Each channel has a container for lipid extraction connected by Acidflex tubing through an AutoAnalyzer pump to a TLC applicator needle. Extraction containers are prepared from disposable Oxford sampler pipet tips by inserting a small cotton filter into their lower, narrower end, which is connected to the pump tubing. The applicator needles are supported vertically in a manifold, and their tips rest on a TLC plate placed on a hot plate. Serum is added to isopropanol in each extraction container, and proteins are completely precipitated in 2 min and retained in the extraction chambers by the cotton filters; lipid extracts are then transferred on to the heated TLC plate by intermittent pumping at a rate allowing for continuous evaporation of isopropanol under streams of warmed air or nitrogen. The lipids accumulate on the plate in eight small spots, one for each channel. Solvent is proportionally added into the extraction chambers from a common reservoir through Acidflex tubing in a second AutoAnalyzer pump. During the extraction procedure, both pump motors are automatically operated by a programmed timer with a solid-state switch. Of several different solvents tested, isopropanol is the fastest for protein precipitation and lipid extraction and does not extract substances from the Acidflex tubing which interfere with chromatographic separation.     

Examination of the interior of sand fly (Diptera: Psychodidae) abdomen reveals novel cuticular structures involved in pheromone release: Discovering the manifold

The males of many species of New World Phlebotomines produce volatile terpenoid chemicals, shown in Lutzomyia longipalpis s.l. to be sex/aggregation pheromones. Pheromone is produced by secretory cells which surround a cuticular reservoir which collects the pheromone and passes it through a cuticular duct to the surface of the insect. The pheromone then passes through specialised cuticular structures on the abdominal surface prior to evaporation. The shape and distribution of the specialised structures are highly diverse and differ according to species. In this study we used SEM to examine the interior cuticular pheromone collection and transport structures of 3 members of the Lu. longipalpis s.l. species complex and Migonemyia migonei. We found a new structure which we have called the manifold which appears to be a substantial extension of the interior tergal cuticle connected in-line with the cuticular duct and reservoir. The manifold of the Campo Grande member of the complex is longer and wider than the Jacobina member whereas the manifold of the Sobral member was shorter than both other members of the complex. Overall, the secretory apparatus of the Sobral member was smaller than the other two. The manifold of M. migonei was very different to those found in Lu. longipalpis s.l. and was positioned in a pit-like structure within the tergal cuticle. The secretory reservoir was connected by a short duct to the manifold. Differences in the size and shape of the manifold may be related to the chemical structure of the pheromone and may have taxonomic value. Examination of the interior cuticle by SEM may help to locate the secretory apparatus of vector species where pheromonal activity has been inferred from behavioural studies but the external secretory structures or pheromones have not yet been found.     

Das Element Stickstoff in der Welt der Briefmarken: Schmuckstücke für die Wissenschaft

The element nitrogen has manifold effects on life. Animals, plants and microorganisms contain the element in the reduced form in many cell components. In the biological nitrogen cycle, mainly microorganisms convert nitrogen into the different oxidation states. The element is a main contributor to the pollution of soil, water and air. Heterocyclic compounds with N as constituent can be toxic or beneficial to mankind. Many aspects of the subject nitrogen can adequately be documented by stamps issued world‐wide. The author can only present a percentage of the large amount of material available.     

Device for evaporation of solvent from small samples

A device for the simultaneous evaporation of six samples under separately controlled streams of nitrogen is described.     

Experimental studies of molecular interactions between nitrogen bases of nucleic acids.

New experimental results concerning molecular interactions between the nitrogen bases of nucleic acids in the crystalline phase and in vacuo are reported. The temperature dependence of the evaporation rate is measured for solid species. The sensitivity of conventional methods of sublimation heat measurements was improved essentially using a quartz resonator serving as a precise sensor of evaporation rate. Sublimation heats were found for both canonical bases and a number of their derivatives. The in vacuo formation of base associates interacting through hydrogen bonds was observed with a field mass spectrometer. The dimer formation enthalpies, which are indicative of a stronger attraction in complementary pairs compared with noncomplementary ones, were derived from the temperature dependence of ionic currents. Hydrogen-bound complexes of more intricate associates (base trimers and aqueous molecules associates) were studied. The energy gain in the formation of trimers of identical molecules was shown to be larger (per base molecule) than that for dimers.     

Semi-automatic liquid chromatographic analysis of pamidronate in urine after derivatization with 1-naphthylisothiocyanate

An existing sensitive chromatographic assay for pamidronate in urine has considerably been automated. Using the same sample processor, the solid-phase extraction (SPE) was automated separately from the derivatization with 1-naphthylisothiocyanate, the two-fold ion-pair liquid–liquid-extraction and the treatment with hydrogen peroxide for the 2–20 ng/ml concentration range. The automatic procedure was preceded by a triple calcium precipitation and interrupted by evaporation of the SPE eluate under nitrogen. For the 0.5–5 μg/ml concentration range one automatic sequence was used by avoiding evaporation during the sample treatment. In addition to the labour-saving of the semi-automatic procedure, the daily sample-throughput was improved compared to the existing manual assay. Further, the validation showed marginal improvements in the precision, accuracy and lower limit of quantification.     

Levan nanostructured thin films by MAPLE assembling

Synthesis of nanostructured thin films of pure and oxidized levan exopolysaccharide by matrix-assisted pulsed laser evaporation is reported. Solutions of pure exopolysaccharides in dimethyl sulfoxide were frozen in liquid nitrogen to obtain solid cryogenic pellets that have been used as targets in pulsed laser evaporation experiments with a KrF* excimer source. The expulsed material was collected and assembled onto glass slides and Si wafers. The contact angle studies evidenced a higher hydrophilic behavior in the case of oxidized levan structures because of the presence of acidic aldehyde-hydrogen bonds of the coating formed after oxidation. The obtained films preserved the base material composition as confirmed by Fourier transform infrared spectroscopy. They were compact with high specific surface areas, as demonstrated by scanning electron and atomic force microscopy investigations. In vitro colorimetric assays revealed a high potential for cell proliferation for all coatings with certain predominance for oxidized levan.     

Multifunctional Solar Waterways: Plasma‐Enabled Self‐Cleaning Nanoarchitectures for Energy‐Efficient Desalination

Evaporating seawater and separating salt from water is one of the most promising solutions for global water scarcity. State‐of‐the‐art water desalination devices combining solar harvesting and heat localization for evaporation using nanomaterials still suffer from several issues in energy efficiency, long‐term performance, salt fouling, light blocking, and clean water collection in real‐world applications. To address these issues, this work devises plasma‐enabled multifunctional all‐carbon nanoarchitectures with on‐surface waterways formed by nitrogen‐doped hydrophilic graphene nanopetals (N‐fGPs) seamlessly integrated onto the external surface of hydrophobic self‐assembled graphene foam (sGF). The N‐fGPs simultaneously transport water and salt ions, absorb sunlight, serve as evaporation surfaces, then capture the salts, followed by self‐cleaning. The sGF ensures effective thermal insulation and enhanced heat localization, contributing to high solar‐vapor efficiency of 88.6 ± 2.1%. Seamless connection between N‐fGPs and sGF and self‐cleaning of N‐fGP structures by redissolution of the captured salts in the waterways lead to long‐term stability over 240 h of continuous operation in real seawater without performance degradation, and a high daily evaporation yield of 15.76 kg m^?2. By eliminating sunlight blocking and guiding condensed vapor, a high clean water collection ratio of 83.5% is achieved. The multiple functionalities make the current nanoarchitectures promising as multipurpose advanced energy materials.     

Use of a chemical tracer to evaluate water movement through two automatic watering rack manifolds during flushing

A sodium fluorescein solution was introduced into an upfeed serpentine and a horizontal automatic watering rack manifold. Water samples were collected from nine drinking valves on each manifold prior to and after flushing at 12 pounds per square inch water pressure for 15 seconds, one minute, and five minutes. The water samples were assayed for fluorescein and it was found that the chemical was effectively removed by flushing from the upfeed serpentine manifold, while significant levels of fluorescein remained in the horizontal manifold even after five minutes flushing.     

Carbon, nitrogen, and sulfur isotope changes and hydro-geological processes in a saline lake chain

The ionic concentrations,conductivity and pH of water in the Lake Chany complex in West Siberian Russia change from the mouth to the interior of the lake. This difference is indicative of marked evaporation of lake water from the closed water body system in the dry climate of Western Siberia. The carbon isotope composition of particulate organic matter (POM, composed mainly of phytoplankton) clearly changes, along with the pH of the water, reflecting the concentration of dissolved CO₂. Carbon and nitrogen isotope signatures of Chironomus plumosus larvae, a benthic invertebrate that may feed on bulk lake sediment, systematically increase, along with those of POM and sediment organic matter (SOM), through the lake chain. Both sulfate-sulfur and nitrogen isotope compositions of the POM and SOM increase with distance from the estuary into the Lake Chany complex. Heavier sulfur and nitrogen isotope recycling from the sediment, caused by microbial sulfate reduction and denitrification, respectively, may have led to the increased sulfate-sulfur and nitrogen isotope compositions of the POM and SOM.     

Using Manifold Learning for Atlas Selection in Multi-Atlas Segmentation

Multi-atlas segmentation has been widely used to segment various anatomical structures. The success of this technique partly relies on the selection of atlases that are best mapped to a new target image after registration. Recently, manifold learning has been proposed as a method for atlas selection. Each manifold learning technique seeks to optimize a unique objective function. Therefore, different techniques produce different embeddings even when applied to the same data set. Previous studies used a single technique in their method and gave no reason for the choice of the manifold learning technique employed nor the theoretical grounds for the choice of the manifold parameters. In this study, we compare side-by-side the results given by 3 manifold learning techniques (Isomap, Laplacian Eigenmaps and Locally Linear Embedding) on the same data set. We assess the ability of those 3 different techniques to select the best atlases to combine in the framework of multi-atlas segmentation. First, a leave-one-out experiment is used to optimize our method on a set of 110 manually segmented atlases of hippocampi and find the manifold learning technique and associated manifold parameters that give the best segmentation accuracy. Then, the optimal parameters are used to automatically segment 30 subjects from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). For our dataset, the selection of atlases with Locally Linear Embedding gives the best results. Our findings show that selection of atlases with manifold learning leads to segmentation accuracy close to or significantly higher than the state-of-the-art method and that accuracy can be increased by fine tuning the manifold learning process.     

The distribution of tree and grass roots in savannas in relation to soil nitrogen and water

Here we describe the fine root distribution of trees and grasses relative to soil nitrogen and water profiles. The primary objective is to improve our understanding of edaphic processes influencing the relative abundance of trees and grasses in savanna systems. We do this at both a mesic (737 mm MAP) site on sandy-loam soils and at an arid (547 mm MAP) site on clay rich soils in the Kruger National Park in South Africa. The proportion of tree and grass fine roots at each soil depth were estimated using the δ¹³C values of fine roots and the δ¹³C end members of the fine roots of the dominant trees and grasses at our study sites. Changes in soil nitrogen concentrations with depth were indexed using total soil nitrogen concentrations and soil δ¹⁵N values. Soil water content was measured at different depths using capacitance probes. We show that most tree and grass roots are located in the upper layers of the soil and that both tree and grass roots are present at the bottom of the profile. We demonstrate that root density is positively related to the distribution of soil nitrogen and negatively related to soil moisture. We attribute the negative correlation with soil moisture to evaporation from the soil surface and uptake by roots. Our data is a snapshot of a dynamic process, here the picture it provides is potentially misleading. To understand whether roots in this system are primarily foraging for water or for nitrogen future studies need to include a dynamic component.     

毛乌素裸沙丘斑块的实际蒸发量及其对降雨格局的响应

 裸沙表面的蒸发虽然是一个物理问题,但对于沙地植被演替的初始阶段非常重要。目前存在的地表蒸发的机理性模型大多是瞬时或者短时期的 ,而年尺度以上的蒸发量与降水和蒸发驱动下的土壤水分系统的状态变化及其对蒸发过程的反馈密切相关。一些估算毛乌素年蒸发量的实验结 果之间分歧很大且缺乏准确的机理性解释。该文利用生态系统模型中的土壤水分运动和蒸发模块计算了毛乌素裸沙丘从日到年际尺度的实际蒸 发量,发展了一个以单次降雨量和降雨频率为驱动因素的降雨-蒸发模型对年蒸发量进行简单的估算,并研究了年蒸发量对降雨格局的响应。结 果表明毛乌素裸沙丘的多年平均蒸发量为166 mm,占多年平均降雨量的56%。虽然研究区1959～1992年降雨总量无显著变化趋势,但是裸沙丘斑 块的实际蒸发量呈现较明显的增加趋势（1.30 mm&;#8226;a^－1）。小降雨事件对蒸发量贡献的显著增加（0.69 mm&;#8226;a^－1）是导致实际蒸发量增大的重 要原因。大强度降雨事件的频度和雨量对降雨总量的贡献要远高于对蒸发总量的贡献,小于12 mm的降雨事件在年际比较稳定,很大程度上保证 了年蒸发量100 mm左右的基数值。这些因素使得年蒸发量的变异程度小于年降雨量的变异程度。由于降雨格局的年际变化会对蒸发量产生直接 的影响,降雨-蒸发模型可以相对有效地预测年度蒸发量,而用年降雨量预测年蒸发量误差较大。     

Interactions between plant nutrients,water and carbon dioxide as factors limiting crop yields

Biomass production of annual crops is often directly proportional to the amounts of radiation intercepted, water transpired and nutrients taken up. In many places the amount of rainfall during the period of rapid crop growth is less than the potential rate of evaporation, so that depletion of stored soil water is commonplace. The rate of mineralization of nitrogen (N) from organic matter and the processes of nutrient loss are closely related to the availability of soil water. Results from Kenya indicate the rapid changes in nitrate availability following rain.<br>Nutrient supply has a large effect on the quantity of radiation intercepted and hence, biomass production. There is considerable scope for encouraging canopy expansion to conserve water by reducing evaporation from the soil surface in environments where it is frequently rewetted, and where the unsaturated hydraulic conductivity of the soil is sufficient to supply water at the energy limited rate (e.g. northern Syria). In regions with high evaporative demand and coarse-textured soils (e.g. Niger), transpiration may be increased by management techniques that reduce drainage.<br>Increases in atmospheric [CO₂] are likely to have only a small impact on crop yields when allowance is made for the interacting effects of temperature, and water and nutrient supply. <br>     

Surface Plasmon Resonance-Based Fiber-Optic Hydrogen Gas Sensor Utilizing Indium–Tin Oxide (ITO) Thin Films

We report experimental study on an indium?Ctin oxide (ITO)-coated surface plasmon resonance-based fiber-optic hydrogen gas sensor operating at room temperature. The sensor works on intensity modulation interrogation. Indium?Ctin oxide (In₂O₃?+?SnO₂) films were grown on unclad core of the fiber by thermal evaporation technique. The surface plasmon resonance (SPR) spectra for 100?% nitrogen gas as well as for a mixture of 4?% hydrogen gas and 96?% nitrogen gas were obtained. In the case of mixture of hydrogen and nitrogen gases, a sharp dip in the SPR spectrum was observed implying that the hydrogen gas changes the dielectric properties of ITO. The performance of the sensor has been studied for different percentages of tin oxide in indium oxide and for different thicknesses of ITO film. Both the parameters have been optimized for the best performance of the sensor.     

接种蚯蚓对秸秆还田土壤碳、氮动态和作物产量的影响

通过为期 2年的小区 (2 .8m× 1.0m)试验 ,研究了旱作水稻 小麦轮作条件下接种蚯蚓对施用玉米秸秆 (第一季用量 15 0 0g·m-2 ,以后各季为 75 0g·m-2 )农田土壤碳、氮动态和作物产量的影响 .结果表明 ,接种 10条·m-2 或 2 0条·m-2 环毛蚓 (Pheretimasp .)对土壤有机碳和全氮含量无显著影响 ,蚯蚓活动未造成土壤C库的衰减 ,土壤碳、氮基本维持平衡 .接种蚯蚓处理土壤N的矿化作用增强 ,矿质N含量提高 ,NO3 - N含量增加 ,而且稻季比麦季增加更为明显 .接种蚯蚓在稻、麦季均能提高微生物量碳、氮含量 ,蚯蚓具有扩大土壤微生物量N库和促进有机N矿化的双重作用 .这种作用在有效C源供应丰富的作物生长发育旺盛期更为明显 .接种蚯蚓对旱作水稻和小麦有一定的增产作用 ,其中水稻的增产幅度达 9.3% ,小麦为 5 .1% .接种蚯蚓后土壤容重明显降低 ,孔隙度显著增加 .蚯蚓在保持土壤C库平衡的同时 ,对于促进秸秆有机肥N素养分的再循环和作物生产力的提高具有重要的生态学意义 .     

Sampling techniques and comparative extraction procedures for quantitative determination of intra- and extracellular metabolites in filamentous fungi

Two methods for rapid sampling and three procedures for extraction of metabolites from the filamentous fungus Monascus ruber were compared. It is shown that arrest of metabolism by either dropping the mycelial cultures in liquid nitrogen or by spraying them on a 60% solution of methanol kept at −40°C followed by rapid centrifugation at −10°C were equally effective. Metabolites were extracted from mycelia using different procedures including acid and alkaline treatments, permeabilization by cold chloroform and extraction by boiling buffered ethanol, to demonstrate that the latter method gave the best results both in terms of recovery and stability of metabolites. In addition, this method is very simple to handle and allows the use of very low amounts (i.e. 10–20 mg dry mass) of cellular material since the removal of ethanol by evaporation after extraction results in a concentration step of metabolites.     

Applications of differential geometry to molecular genetics

A mathematical formalism is presented in which changes in information content of an evolving DNA (deoxyribonucleic acid) molecule may be described. The basic construct is a 65-dimensional differentiable manifold (the informational space-time manifold) in a coordinate structure such that the manifold points represent (i) the number of each codon type in a DNA molecule, and (ii) the evolutionary time of that DNA. It is shown that this manifold cannot be Euclidean but must be taken, at least conditionally, to be Riemannian. Evolutionary motions in the informational space-time manifold are initially postulated to be geodesics, and evolutionary equations-of-motion are elaborated. These equations are governed by an evolutionary field which is produced by the intrinsic structure of the manifold. The concept of genetic cosmology is introduced, and a manifold in which the evolutionary field is weak and depends only upon the evolutionary time is investigated. The nature of empirical input into genetic cosmology is discussed.Work supported by the U.S. Department of Energy.     

凹凸棒土添加对土壤蒸发及裂缝特征的影响

水分是限制干旱与半干旱地区植被恢复和农业发展的最重要因素之一,减少土壤水分无效蒸发损失可提高水分利用效率。凹凸棒土(ATP)作为一种黏土矿物,其亲水性和吸附性对限制土壤蒸发具有重要作用。本研究选取黄土高原干旱与半干旱区3种不同质地的典型土壤(黑垆土、黄绵土、风沙土),设置5种ATP添加量(0%、1%、2%、3%、4%),使用微型蒸发器在自然条件下进行土壤蒸发试验,探究ATP添加对不同土壤蒸发过程和蒸发面裂缝特征的影响。结果表明: 当ATP添加量<3%时,在同一种土壤下累积蒸发量与蒸发损失率随ATP添加量的增加而减小;ATP添加量为3%时,黑垆土、风沙土的累积蒸发量和蒸发损失率均减小,黄绵土的累积蒸发量和蒸发损失率增加;ATP添加量为4%时,黑垆土的累积蒸发量减小、蒸发损失率增加,风沙土的累积蒸发量增加、蒸发损失率减小,黄绵土的累积蒸发量和蒸发损失率均减小。不同土壤平均累积蒸发量表现为:黑垆土>黄绵土>风沙土。在同一种土壤的整个蒸发过程中,施加ATP处理的土壤含水量始终高于对照。累积蒸发量与时间平方根关系的模拟结果表明,蒸发结束时ATP处理下土壤样品可以释放的水量高于对照。添加ATP后黑垆土和黄绵土的裂缝面密度显著增加,风沙土裂缝面密度随ATP添加量的增加而增加,3种土壤的裂缝面密度在ATP添加量为4%时均达到最大值。ATP添加量为3%时可以在最大程度上减少土壤水分无效蒸发。