Protective role of exogenous nitric oxide against oxidative-stress induced by salt stress in barley (Hordeum vulgare)

To probe into the potential of relieving the oxidative damage of salt stress, we investigated the protective role of nitric oxide on barley under salt stress. Salt stress resulted in increased ion leakage, lipid peroxidation and protein oxidation in barley leaves. Simultaneous treatments of barley leaves with 50 microM sodium nitroprusside, a nitric oxide donor, alleviated the damage of salt stress, reflected by decreased ion leakage, and malendialdehyde (MDA), carbonyl, and hydrogen peroxide content in barley leaves. The presence of the nitric oxide donor increased the activities of superoxide dismutases (SOD), ascorbate peroxidases (APX), and catalases (CAT). Meantime, sodium nitroprusside addition increased accumulation of ferritin at the protein level, indicating that nitric oxide directly regulated ferritin accumulation. These results suggested that nitric oxide can effectively protect seedlings from salt stress damage by enhancing activities of antioxidant enzymes to quench the excessive reactive oxygen species caused by salt stress and inducing the increase of ferritin accumulation to chelate larger number of ferrous ion. Information from this study can be used to improve soil management practices for sustainable use of salt-affected soils in the future.     

Preparation of D-histidine modified zeolitic imidazolate framework-90 coated capillary column and its application in open-tube capillary electrochromatography enantioseparation

Metal-organic framework materials are a class of novel crystalline porous materials with regular pore structures formed by covalent bonding between metal centers and organic functional groups. Metal-organic framework materials have attracted great interest in analytical chemistry due to their unique properties such as good stability and permanent porosity. In this work, D-histidine was used to carry out chiral modification of zeolitic imidazolate framework-90 under mild conditions, and the D-histidine modified zeolitic imidazolate framework-90 coated capillary column was prepared. This chiral capillary column was used to separate epinephrine, norepinephrine, terbutaline, and tryptophan enantiomers. Under optimum conditions, baseline separations were achieved. The intra-day, inter-day, and inter-column relative standard deviations (n = 3) of the four pairs of enantiomeric migration times were 0.15%–0.56%, 0.74%–2.40%, and 1.93%–3.18%, respectively. Moreover, the D-histidine modified zeolitic imidazolate framework-90 coated capillary could be reused for at least 150 runs without significant changes in the separation efficiency and migration time.     

Entrainment-mixing parameterization in shallow cumuli and effects of secondary mixing events

Parameterization of entrainment-mixing pro- cesses in cumulus clouds is critical to improve cloud parameterization in models, but is still at its infancy. For this purpose, we have lately developed a formulation to represent a microphysical measure defined as homoge- neous mixing degree in terms of a dynamical measure defined as transition scale numbers, and demonstrated the formulation with measurements from stratocumulus clouds. Here, we extend the previous work by examining data from observed cumulus clouds and find positive cor- relations between the homogeneous mixing degree and transition scale numbers. These results are similar to those in the stratocumulus clouds, but proved valid for the first time in observed cumulus clouds. The empiricalrelationships can be used to parameterize entrainment- mixing processes in two-moment microphysical schemes. Further examined are the effects of secondary mixing events on the relationships between homogeneous mixing degree and transition scale numbers with the explicit mixing parcel model. The secondary mixing events are found to be at least partially responsible for the larger scatter in the above positive correlations based on obser- vations than that in the previous results based on numerical simulations without considering secondary mixing events.     

高寒草甸土壤微生物量及酶活性的研究

为揭示高寒草甸土壤微生物量和土壤酶活性特征,以青藏高原金露梅(Potentilla frutisosa)丛间草地和矮嵩草(Kobresia humilis)草甸为研究对象,分析了其土壤理化性质、土壤微生物量、微生物贡献率、土壤酶活性特征.结果表明:矮嵩草草甸土壤全氮、全磷、微生物碳(氮、磷)、微生物氮(磷)贡献率、土壤脲酶、过氧化氢酶、多酚氧化酶活性均显著大于金露梅丛间草地;而土壤有效磷、磷酸酶活性均显著小于金露梅丛间草甸;2种类型草甸的土壤有机质、微生物碳贡献率没有显著差异;2种类型草甸的土壤微生物量对土壤营养库的贡献率均在较低水平.说明高寒草甸在植被生长旺季土壤微生物量呈现较高的水平;而微生物量对土壤营养库比值略偏低.矮嵩草草甸比金露梅丛间草地更有利于土壤养分的提高以及土壤微生物的生长和繁殖.     

Use of a “Catalytic” Cosolvent,N,N‐Dimethyl Octanamide,Allows the Flow Synthesis of Imatinib with no Solvent Switch

A general, efficient method for C?N cross‐coupling has been developed using N,N‐dimethyloctanamide as a catalytic cosolvent for biphasic continuous‐flow applications. The described method was used to generate a variety of biarylamines and was integrated into a two‐step sequence which converted phenols into biarylamines via either triflates or tosylates. Additionally, the method was applied to a three‐step synthesis of imatinib, the API of Gleevec, in good yield without the need of solvent switches.     

The synergistic inhibition effect between imidazoline-based dissymmetric bis-quaternary ammonium salts and thiourea on Q235 steel in CO2 corrosion process

Research on Chemical Intermediates - The inhibition effect of imidazoline-based dissymmetric bis-quaternary ammonium salt (DBA) and Thiourea (TU) on Q235 steel in CO2-saturated simulated...     

Synthesis and Characterization of Diorganocobalt Chlorides by Aliphatic Vinylic C–Cl Bond Activation

Three diorganocobalt chlorides [CoClMe(PMe₃)₂–{(C₅H₆)–CH=O}] ( 4 ), [CoClMe(PMe₃)₂–{(C₆H₈)–CH=O}] ( 5 ), and [CoClMe(PMe₃)₂–{(C₆H₇Memeta)–CH=O}] ( 6 ) were synthesized through cyclometalation reactions with aldehyde as an anchoring group involving aliphatic vinylic C–Cl bond activation. Complexes 4 – 6 were characterized by IR and NMR spectroscopy. The crystal and molecular structures of complexes 4 and 5 were determined by single‐crystal X‐ray diffraction. Complexes 4 – 6 are stable in solution at room temperature, but they decompose at above 30 °C affording C,C‐couplings products with the formation of [Co(PMe₃)₃Cl]. The results of this work will be important for people to deepen the understanding of the C–Cl bond activation mechanism.     

Optical absorption and emission properties of benzene-expanded Janus AT nucleobase analogues: A DFT study

We design benzene-expanded Janus AT bases (J-AT1, J-AT2, BF1 and BF2) and investigate the structural and optical properties of these bases using DFT and TDDFT methods and also consider the effect of water solution and base pairing. The results show that J-AT1 has a nonplanar structure and its amino group is more asymmetric than the other three bases. J-AT1 and BF1 exist intramolecular H-bonds. The Janus AT base pairs exist three intermolecular H-bonds: NH···N has the largest energy, followed by NH···O and CH···O. The Janus AT base pairs retain the strength of H-bonds and maintain the stability of the base pair. The lowest absorption and emission wavelengths of the benzene-expanded Janus AT bases are all assigned to ππ* character arising from HOMO to LUMO transition, and they exhibit redshift due to the increase in effective conjugation length with the introduction of benzene. The excited state assignments in water solution are one-to-one correspondence to those in gas phase. The lowest absorption and emission wavelength of J-AT1 is blueshift, while J-AT2, BF1 and BF2 bases are redshift as compared to those in gas. The TD-B3LYP method predicts that the first excitation wavelengths of Janus AT base pairs are local excitation on the Janus AT base moieties, which is coincident with the result of CAM-B3LYP and M062X functional. Base pair can influence the excitation properties of base monomer. The results obtained from this theoretical investigation confirm that the position of benzene ring significantly influences the structure and optical properties of the Janus AT bases.     

Fluorescence sensor for water in organic solvents prepared from covalent immobilization of 4-morpholinyl-1, 8-naphthalimide

A new fluorescent dye, N-allyl-4-morpholinyl-1,8-naphthalimide (AMN), was synthesized as a fluorescence indicator in the fabrication of a sensor for determining water content in organic solvents. To prevent leakage of the fluorophore, AMN was photo-copolymerized with acrylamide, (2-hydroxyethyl)methacrylate, and triethylene glycol dimethacrylate on a glass surface treated with a silanizing agent. The sensing mechanism is based on the solvatochromic feature of the covalently immobilized AMN. The fluorescence intensity of AMN decreased with increasing water contents when it was excited at 400 nm. In the range of ca. 0.00–4.40% (v/v), the fluorescence intensity of AMN changed as a linear function of water content. The sensor exhibited satisfactory reproducibility, reversibility, and a response time (t ₉₉) of the order of 50 s. The detection limit was solvent-dependent, when acetonitrile was used as the solvent, and the detection limit could be as low as 0.006% (v/v) of water. Additionally, the prepared sensor is pH-insensitive and possesses a relatively long lifetime of at least one month.