力“球”稳定 德国NOVOFLEX/路华仕Magic Ball云台

球形云台的快速灵活是三维云台无法比拟的。无论是体育、风光还是其他题材,你都可以看到球台的身影。球形云台的样子不仅是传统的下大上小,今天我们就以路华仕这款特殊的球台为例,为你讲述它的使用方法和注意事项。     

A „Magic Mushroom“ Multi-Product Sesquiterpene Synthase

Psilocybe “magic mushrooms” are chemically well understood for their psychotropic tryptamines. However, the diversity of their other specialized metabolites, in particular terpenoids, has largely remained an open question. Yet, knowledge on the natural product background is critical to understand if other compounds modulate the psychotropic pharmacological effects. CubA, the single clade II sesquiterpene synthase of P. cubensis, was heterologously produced in Escherichia coli and characterized in vitro, complemented by in vivo product formation assays in Aspergillus niger as a heterologous host. Extensive GC-MS analyses proved a function as multi-product synthase and, depending on the reaction conditions, cubebol, β-copaene, δ-cadinene, and germacrene D were detected as the major products of CubA. In addition, mature P. cubensis carpophores were analysed chromatographically which led to the detection of β-copaene and δ-cadinene. Enzymes closely related to CubA are encoded in the genomes of various Psilocybe species. Therefore, our results provide insight into the metabolic capacity of the entire genus.     

力“球”稳定 德国NOVOFLEX/路华仕Magic Ball云台

球形云台的快速灵活是三维云台无法比拟的。无论是体育、风光还是其他题材,你都可以看到球台的身影。球形云台的样子不仅是传统的下大上小,今天我们就以路华仕这款特殊的球台为例,为你讲述它的使用方法和注意事项。     

The Formation of Clusters with Reactive Species Precursors to Aerosol Formation in the Ammonia—Sulfur Dioxide System

Reactions between ammonia and sulfur dioxide are known to form aerosols, but no information on the precursors to particle formation are available in the literature. Herein, the first results on the formation of clusters containing both ammonia and sulfur dioxide are presented. Clusters produced by expansion through a dual nozzle into vacuum have been investigated using a molecular beam mass spectrometer technique. Interestingly, under similar expansion conditions, NH₃ incorporation into SO₂ clusters is more extensive than SO₂ into NH₃ clusters. In contrast to findings from the stoichiometry of the solid precipitate of the aerosol, the cluster distributions fail to reveal clusters of any stoichiometry as particularly abundant or stable, except for NH⁺ ₄·NH₃·SO₂.     

Formation of a Δ7 triterpene alcohol in refined olive oils

The triterpene alcohol fraction in several virgin olive oils and the corresponding oils refined by alkali and by physical processes was analyzed by gas chromatography. A Δ⁷ compound was detected in all refined olive oils but not in virgin olive oils. This compound was tentatively identified by gas chromatography-mass spectrometry as 24-methyl-5α-lanosta-7,24-dien-3β-ol, a 24-methylenecycloartanol isomer produced during the refining process by the opening of the 9, 19 cyclopropane ring with formation of a double bond in the Δ⁷ position and the translocation of a double bond in the side chain from the 24–28 to the 24–25 position.     

Study on NO_x Formation in CH_4/Air Jet Combustion

1 INTRODUCTION The nitrogen oxides formed in combustion sys- tems is a significant source of environmental pollution. Nitrogen oxides consist of nitric oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O). NO and NO2 are collectively referred to NOx[1]. In laminar flames, and at the molecular level within turbulent flames, the formation of NOx can be attributed to three distinct chemical kinetic processes. The NOx formed by these three processes is described as thermal NOx, …     

Recent Advances in Electrochemical,Ni-Catalyzed C−C Bond Formation

Nickel-catalyzed cross-electrophile coupling (XEC) is an efficient method to form carbon-carbon bonds and has become an important tool for building complex molecules. While XEC has most often used stoichiometric metal reductants, these transformations can also be driven electrochemically. Electrochemical XEC (eXEC) is attractive because it can increase the greenness of XEC and this potential has resulted in numerous advances in recent years. The focus of this review is on electrochemical, Ni-catalyzed carbon-carbon bond forming reactions reported since 2010 and is categorized by the type of anodic half reaction: sacrificial anode, sacrificial reductant, and convergent paired electrolysis. The key developments are highlighted and the need for more scalable options is discussed.     

Third Phase Formation in the Extraction of Inorganic Acids by TBP in n‐Octane

Abstract

The extraction of HNO₃, HClO₄, H₂SO₄ and H₃PO₄ by 20% (v/v) TBP (0.73 M) in n‐octane was measured under identical conditions up to and beyond the critical point of third phase formation (Limiting Organic Concentration, or LOC condition). The data, together with those obtained previously for HCl, allowed us to establish the following lyotropic series of effectiveness with respect to third phase formation in the extraction of acids by TBP: HClO₄>H₂SO₄>HCl>H₃PO₄>HNO₃. This series correlates with the amount of water present into the organic phase at the point of phase splitting. This result reinforces the validity of the reverse micellar model developed previously for the extraction of metal salts by TBP. The measurements of LOC values as a function of temperature revealed major differences among the acid‐TBP systems investigated. For HClO₄, the strong increase of the LOC value with increasing temperatures is accompanied by a large favorable entropy change. The opposite is true for HCl, while H₂SO₄ and H₃PO₄ represent intermediate cases. Measurements of the LOC values for the extraction of HClO₄ by TBP dissolved in a series of diluents confirmed that topological parameters, such as the Connectivity Index, CI, are useful for predicting the critical condition for phase splitting in different diluents. Based on the linear correlation between LOC values for HClO₄ and CI values of diluents, the effective Connectivity Index of the French nuclear reprocessing diluent, HTP, a complex mixture of highly branched alkanes, was determined.     

Protein Backbone Alteration in Non-Hairpin β-Turns: Impacts on Tertiary Folded Structure and Folded Stability

The importance of β-turns to protein folding has motivated extensive efforts to stabilize the motif with non-canonical backbone connectivity. Prior work has focused almost exclusively on turns between strands in a β-sheet (i. e., hairpins). Turns in other structural contexts are also common in nature and have distinct conformational preferences; however, design principles for their mimicry remain poorly understood. Here, we report strategies that stabilize non-hairpin β-turns through systematic evaluation of the impacts of backbone alteration on the high-resolution folded structure and folded stability of a helix-loop-helix prototype protein. Several well-established hairpin turn mimetics are shown detrimental to folded stability and/or hydrophobic core packing, while less-explored modification schemes that reinforce alternate turn types lead to improved stability and more faithful structural mimicry. Collectively, these results have implications in control over protein folding through chemical modification as well as the design of protein mimetics.     

Defects Formation and Morphology in Large-sized MoSi_2 Rod Prepared by Continuous Extrusion

Incidence of defects in MoSi2 rods prepared by continuous extrusion is dependent on the viscosity of binder. Generally, low viscosity results in surface defects while high viscosity is responsible for inner defects. Cross-section observations indicated that the typical inner defects in sintered MoSi2 rods were large fissure cavity, multiple small holes and single small cavity, of which the characteristic ultrasonic reflection patterns have been experimentally established. Formation of the inner defects is attributed to the inhomogeneous feedstock moving behavior in die, which is aggravated with increasing viscosity of binder. Defect free MoSi2 rods were prepared successfully via continuous extrusion by carefully controlling the viscosity of binder.     

SANS Study of Third Phase Formation in the Extraction of HCl by TBP Isomers in n‐Octane

Abstract

Third phase formation in the extraction of HCl by triisobutyl phosphate (T‐iso‐BP) and tri‐sec‐butyl phosphate (T‐sec‐BP) has been investigated and compared with the tri‐n‐butyl phosphate (T‐n‐BP) system. The three TBP isomers exhibit comparable affinities for HCl, but the branched isomers extract much more water than the linear one. For T‐sec‐BP, the LOC (limiting HCl organic concentration) is characterized by much lower HCl concentrations both in the organic and aqueous phase than for the other isomers. SANS data for T‐iso‐BP and T‐sec‐BP organic phases loaded with progressive amounts of HCl have been interpreted using the Baxter model for hard spheres with surface adhesion. The critical values of the stickiness parameter, τ^?1, and the interaction potential energy, U(r), are slightly different and characteristic for each of the extractants. Their values are consistent with the expectation derived from the micellar interaction model.     

Impacts of heterogeneity in soil fertility on legume-finger millet productivity,farmers’ targeting and economic benefits

Targeting of integrated management practices for smallholder agriculture in sub-Saharan Africa is necessary due to the great heterogeneity in soil fertility. Experiments were conducted to evaluate the impacts of landscape position and field type on the biomass yield, N accumulation and N₂-fixation by six legumes (cowpea, green gram, groundnut, mucuna, pigeonpea and soyabean) established with and without P during the short rain season of 2005. Residual effects of the legumes on the productivity of finger millet were assessed for two subsequent seasons in 2006 in two villages in Pallisa district, eastern Uganda. Legume biomass and N accumulation differed significantly (P < 0.001) between villages, landscape position, field type and P application rate. Mucuna accumulated the most biomass (4.8–10.9 Mg ha⁻¹) and groundnut the least (1.0–3.4 Mg ha⁻¹) on both good and poor fields in the upper and middle landscape positions. N accumulation and amounts of N₂-fixed by the legumes followed a similar trend as biomass, and was increased significantly by application of P. Grain yields of finger millet were significantly (P < 0.001) higher in the first season after incorporation of legume biomass than in the second season after incorporation. Finger millet also produced significantly more grain in good fields (0.62–2.15 Mg ha⁻¹) compared with poor fields (0.29–1.49 Mg ha⁻¹) across the two villages. Participatory evaluation of options showed that farmers preferred growing groundnut and were not interested in growing pigeonpea and mucuna. They preferentially targeted grain legumes to good fields except for mucuna and pigeonpea which they said they would grow only in poor fields. Benefit-cost ratios indicated that legume-millet rotations without P application were only profitable on good fields in both villages. We suggest that green gram, cowpea and soyabean without P can be targeted to good fields on both upper and middle landscape positions in both villages. All legumes grown with P fertiliser on poor fields provided larger benefits than continuous cropping of millet.     

Flavin-Dependent Monooxygenases NotI and NotI′ Mediate Spiro-Oxindole Formation in Biosynthesis of the Notoamides

The fungal indole alkaloids are a unique class of complex molecules that have a characteristic bicyclo[2.2.2]diazaoctane ring and frequently contain a spiro-oxindole moiety. While various strains produce these compounds, an intriguing case involves the formation of individual antipodes by two unique species of fungi in the generation of the potent anticancer agents (+)- and (−)-notoamide A. NotI and NotI′ have been characterized as flavin-dependent monooxygenases that catalyze epoxidation and semi-pinacol rearrangement to form the spiro-oxindole center within these molecules. This work elucidates a key step in the biosynthesis of the notoamides and provides an evolutionary hypothesis regarding a common ancestor for production of enantiopure notoamides.     

“Click” reactions in polysaccharide modification

Polysaccharide chemistry is enjoying accelerating development thanks to advances in synthetic techniques, biochemistry and solvents, which enable polysaccharide materials to be useful in a variety of demanding applications. Among the synthetic advances, click chemistry has reconfigured the realm of polysaccharide modification that previously was dominated by conventional synthetic approaches such as esterification and etherification. “Click” reactions provide mild, modular, and efficient modification pathways, and equally importantly allow us to synthesize derivatives with novel functionality, architecture, and properties, that are otherwise difficult to obtain via conventional methods. Herein, we review application in polysaccharide modification of six groups of click reactions; CuAAC (copper catalyzed alkyne/azide cycloaddition), metal-free [3+2] cycloaddition, Diels–Alder reaction, oxime click, thiol-Michael reaction, and thiol-ene reaction, as well as one click-like reaction that is the subject of our own research, olefin cross-metathesis.