无叶假木贼和盐爪爪提取物的抗菌活性

无叶假木贼和盐爪爪地上部分乙醇提取物、不同溶剂萃取部分对供试病原细菌和真菌均表现出较好的抑制作用,其乙酸乙酯萃取部分和正丁醇萃取部分的抗菌活性明显强于石油醚萃取部分和水部分。结果表明,无叶假木贼中抗菌活性成分主要为极性中等的化合物,且很可能是具弱碱性、易与酸成盐的生物碱类。盐爪爪中抗菌活性成分同样为极性中等的化合物。     

国产假木贼属植物微形态特征及其生态意义

利用体视显微镜对国产假木贼属8种植物的微形态特征进行了观察.结果表明:该属植物的形态可分为两大类:(1)无瘤状茎基,如:高枝假木贼(Anabasis elatior)、短叶假木贼(A.brevifolia)、无叶假木贼(A.aphylla)和盐生假木贼(A.salsa);(2)具瘤状茎基,如:粗糙假木贼(A.pelliotii)、白垩假木贼(A.cretacea)、展枝假木贼(A.truncata)和毛足假木贼(A.eriopoda);再通过叶形态的变化规律,如弧状弯曲,鳞片状或三角钻形等来甄别种的属性.实验证明:假木贼属植物叶的微形态特征具有高度的种间专属性和稳定的遗传性,可以作为假木贼属种分类的重要依据,该类植物由于长期生存在干旱环境下,形成了一系列抵御干旱逆境的典型的超旱生的形态特征,在根、茎和叶3个方面均得以充分体现.因此,研究其形态学和生态学的进化机制,对当前植物抗逆育种、生态环境恢复等都具有重要意义.     

Extraction of indole alkaloids fromCatharanthus roseus by using supercritical carbon dioxide

Summary Indole alkaloids, particularly vindoline and catharanthine, were extracted from the leaves ofCatharanthus roseus by supercritical extraction with CO₂. The contents of vindoline and catharanthine in the extracts were determined by HPLC and identified by LC/MS. About 52 %(w/w) of the initial vindoline content, 1.5 mg vindoline/g dry wt leaves, was recovered after extracting this material for 10 h with the CO₂ flow rate of 400 ml/min at 40°C and 150 bar. Vindoline concentration in the extract was 67 %(w/w).     

Plant water uptake from soil through a vapor pathway

Water uptake from the soil via a vapor pathway was tested. Viburnum suspensum L. plants were divided into: (1) irrigated, (2) drought with vapor and (3) drought without vapor treatments. Each plant was placed into a larger bucket containing deuterium-labeled water as a vapor source (vapor treatment) or no water (drought and irrigation treatments). We also tested whether uptake via a vapor pathway could mitigate drought effects. Net CO₂ assimilation (A), transpiration (E) and stomatal conductance (gs) were measured daily until the first visible signs of stress. Soil water content, stem water potential (Ψ) and the stable hydrogen isotope ratio (δ²H) of soil and plant xylem water were then measured in all treatments. We show that water is taken up by plants through the vapor phase in dry soils. The δ²H values of the soil water in the vapor treatment were highly enriched compared to the background isotope ratios of the non-vapor exposed irrigated and drought treatments. Stem water δ²H values for the vapor treatment were significantly greater than those for irrigation and drought treatments not exposed to isotopically enriched vapor. In this experiment, movement of water to the plant via the vapor phase did not mitigate drought effects. A, E, plant Ψ and gs significantly decreased in the drought and vapor treatments relative to the controls, with no significant differences between vapor and drought treatments.     

Extraction of phosphorus from the major soils of Cyprus with water or bicarbonate

Summary Phosphorus was extracted from the five major types of Cyprus soils, ranging in CaCO₃ content from 0 to 71%, using the Pw and the bicarbonate method. With three of these soils the two methods gave identical index values. However, bicarbonate extracted more P from the highly calcareous soil and less P from the igneous soil relative to the Pw method.Reproducibility of both methods was found satisfactory.     

短叶假木贼中化学成分的分离和结构鉴定

从短叶假木贼(Anabasis brevifolia)的氯仿提取物中分离得到了9个化合物,经UVI、R、MS和NMR等波谱技术分析,并结合文献对照,确定其结构为-Ncis-feruloyltyramine(1)、N-trans-feruloyltyramine(2)、-Ncis-feruloyl-3-methoxytyramine(3)、-Ntrans-feruloyl-3-methoxytyramine(4)、3′,5,7-trihydroxy-4,′6-dimethoxy flavonoid(5)、eupatilin(6)、丁香脂素(7)、β-谷甾醇(8)、β-谷甾醇3-O-β-D-吡喃葡萄糖苷(9)。这些化合物均为首次从假木贼属(AnabasisL.)植物中分离得到。     

Regulation of silk material structure by temperature-controlled water vapor annealing

We present a simple and effective method to obtain refined control of the molecular structure of silk biomaterials through physical temperature-controlled water vapor annealing (TCWVA). The silk materials can be prepared with control of crystallinity, from a low content using conditions at 4 °C (α helix dominated silk I structure), to highest content of ～60% crystallinity at 100 °C (β-sheet dominated silk II structure). This new physical approach covers the range of structures previously reported to govern crystallization during the fabrication of silk materials, yet offers a simpler, green chemistry, approach with tight control of reproducibility. The transition kinetics, thermal, mechanical, and biodegradation properties of the silk films prepared at different temperatures were investigated and compared by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), uniaxial tensile studies, and enzymatic degradation studies. The results revealed that this new physical processing method accurately controls structure, in turn providing control of mechanical properties, thermal stability, enzyme degradation rate, and human mesenchymal stem cell interactions. The mechanistic basis for the control is through the temperature-controlled regulation of water vapor to control crystallization. Control of silk structure via TCWVA represents a significant improvement in the fabrication of silk-based biomaterials, where control of structure-property relationships is key to regulating material properties. This new approach to control crystallization also provides an entirely new green approach, avoiding common methods that use organic solvents (methanol, ethanol) or organic acids. The method described here for silk proteins would also be universal for many other structural proteins (and likely other biopolymers), where water controls chain interactions related to material properties.     

Errors in differential infrared carbon dioxide analysis resulting from water vapor

Water vapor was added differentially to the gas streams entering the cells of three makes of differential infrared carbon dioxide analysers. Analyser deflections were compared with those expected from dilution of the carbon dioxide by the additional gas. Tests were made at 0, 365, and 730 cm³ m^–3 concentrations of carbon dioxide, and with the dewpoint in one cell of the analysers held constant at 15, 20, or 25°C. None of the analysers always responded in the ways predicted from dilution. The results showed that errors of a few cm³ m^–3 could occur in estimates of carbon dioxide differentials using the theoretical correction for dilution. Furthermore the amount of error varied with the carbon dioxide range, the difference in water content, and in some cases the dewpoint range.     

Emission from a transverse volume discharge in neon with small admixtures of water vapor and air

Emission from the plasma of a pulsed discharge in neon with small admixtures of water vapor and air in the wavelength range 210–620 nm is investigated. A transverse volume discharge with spark UV preionization is ignited in neon at a pressure of 100–200 kPa and charging voltage of U _ch≤20 kV. It is shown that the discharge acts as a source of pulsed UV radiation on OH(A-X) (λ=308–314 nm) and NO(B-X) (247.8 nm) transitions, which is of interest for the use in an ecologically safe lamp based on the mixtures of neon with water vapor and air. In the visible spectral region, plasma emission consists of the NeI (3s, 3s′-3p, 3p′) band and H_β 486.1-nm spectral line. On the short-wavelength side of the spectrum, a broadband emission (the third continuum of neon) is observed, whose intensity increases with increasing neon pressure and decreasing emission wavelength.     

Interaction of the peptide bond with solvent water: a vapor phase analysis

A dynamic technique, using radioactivity as a means of detection, makes it possible to measure the partial pressures of highly polar compounds in dilute aqueous solution. The results can be expressed in terms of the dimensionless distribution coefficient for transfer of a compound from dilute aqueous solution to the vapor phase. For acetic acid this coefficient is 1.1 X 10(-5), for acetamide 7.6 X 10(-8), for N-methylacetamide 4.1 X 10(-8), and for N,N-dimethylacetamide 5.4 X 10(-7). Thus acetamide is much more strongly solvated than the uncharged acetic acid molecule. The results suggest: (1) that the peptide bond represents an extreme among uncharged functional groups in the degree to which it is stabilized by solvent water; (2) that the very great hydrophilic character of the peptide bond may be associated mainly with hydrogen bonding of the solvent to the carbonyl oxygen atom (rather than the N-H group); and (3) that the observed equilibria of biosynthesis and hydrolysis of peptide bonds in aqueous solution are largely determined by differences between reactants and products in their free energies of solvation. It is anticipated that where "bound" water is found in proteins, it will often be found to be associated with peptide bonds, and will tend to be associated with the C-O group rather than with the N-H group.     

Extraction of protein and amino acids from deoiled rice bran by subcritical water hydrolysis

This study investigated the production of value-added protein and amino acids from deoiled rice bran by hydrolysis in subcritical water (SW) in the temperature range between 100 and 220 degrees C for 0-30 min. The results suggested that SW could effectively be used to hydrolyze deoiled rice bran to produce useful protein and amino acids. The amount of protein and amino acids produced are higher than those obtained by conventional alkali hydrolysis. The yields generally increased with increased temperature and hydrolysis time. However, thermal degradation of the product was observed when hydrolysis was carried out at higher temperature for extended period of time. The highest yield of protein and amino acids were 219 +/- 26 and 8.0 +/- 1.6 mg/g of dry bran, and were obtained at 200 degrees C at hydrolysis time of 30 min. Moreover, the product obtained at 200 degrees C after 30 min of hydrolysis exhibited high antioxidant activity and was shown to be suitable for use as culture medium for yeast growth.