435 research outputs found

    ChemInform Abstract: Microwave‐Assisted, Mild, Facile, and Rapid One‐Pot Three‐Component Synthesis of Some Novel Pyrano[2,3‐d]pyrimidine‐2,4,7‐triones.

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    Novel pyrano[2,3-d]pyrimidine-2,4,7-triones were synthesized in 90–97% yield via a three-component reaction of an aromatic aldehyde, Meldrums acid, and barbituric acid in the presence of 10 mol % K2CO3 under microwave irradiation. This is the first protocol to be reported for the synthesis of title compounds and the significant features of the present protocol are simplicity, high yields, short reaction time, involvement of aqueous work-up procedure, environmentally benign nature, and no chromatographic purification

    Simple and Efficient Protocol for the Synthesis of Novel Dihydro-1H-Pyrano[2,3-C]Pyrazol-6-Ones via a one-Pot Four-Component Reaction

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    Ba(OH)2 catalyzed simple and efficient one-pot four-component reaction of Meldrums acid, ethyl acetoacetate, hydrazine hydrate, and aromatic aldehydes to give 3-methyl-4-aryl-4,5-dihydro-1H-pyrano[2,3-c]pyrazol-6-ones in refluxing water is reported. The yields are high and the reactions go to completion in 1-2 h

    On Generalized Recurrent Finsler Spaces of Higher Order with Berwald’s Curvature Tensor

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    In this present paper, we introduced a Finsler space Fn which projective curvature tensor K^i_ijkh satisfies the generalized five recurrence property with respect to Berwald’s connection parameters G^i_kh, we have derived some theorems and some identities along with few more related results in a recurrent and generalized 5-recurrent Finsler space with Berwald’s curvature tensor field

    ChemInform Abstract: One‐Pot Four‐Component Synthesis of Some Novel Octahydroquinolindiones Using ZnO as an Efficient Catalyst in Water

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    ZnO has been shown to be an inexpensive, efficient, readily available, and mild catalyst for a one-pot four-component synthesis of some novel octahydroquinolindione-3-carboxylic acid ethyl esters using diethylmalonate, dimedone, ammonium acetate, and appropriate aromatic aldehydes in water at reflux. ZnO acts as a recyclable heterogeneous catalyst to afford the products in excellent yield in short reaction duration

    Nonenzymatic Exogenous and Endogenous Antioxidants

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    Nonenzymatic exogenous and endogenous antioxidants play an important role in human health and act as preservatives for cosmetics, pharmaceuticals, and food products. This chapter will discuss the chemical structure and mechanism of action of the most important nonenzymatic small exogenous and endogenous organic molecules that act as antioxidants. The chapter will focus on the structural features, functional groups, properties, biosynthetic origin, and mechanism of action of such antioxidants. It also covers damages that free radicals create and the mechanisms by which they are neutralized by the various antioxidants. The scope of this chapter will be limited to nonenzymatic exogenous and endogenous antioxidants since enzymatic antioxidants have been discussed extensively in several reviews

    Optimizing a Texas Industrial Remcor Solenoid Valve for Pulse-Width Modulation Applications

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    The objectives ofthis research are: To model the dynamic response ofa solenoid valve to explore the parameters that have some effect on the valve perfonnance, To modifY, based on the dynamic model, the part(s) of the valve that have some influence on the valve performance, To investigate about the effect ofthe operational conditions, like voltage and pressure, then to run a test to observe the results, and To compare the performance ofthe original valve with the modified valve in terms of response time

    Transcriptomes of Plant Gametophytes Have a Higher Proportion of Rapidly Evolving and Young Genes than Sporophytes

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    eproductive traits in plants tend to evolve rapidly due to various causes that include plant-pollinator coevolution and pollen competition, but the genomic basis of reproductive trait evolution is still largely unknown. To characterize evolutionary patterns of genome wide gene expression in reproductive tissues in the gametophyte and to compare them to developmental stages of the sporophyte, we analyzed evolutionary conservation and genetic diversity of protein-coding genes using microarray-based transcriptome data from three plant species, Arabidopsis thaliana, rice (Oryza sativa), and soybean (Glycine max). In all three species a significant shift in gene expression occurs during gametogenesis in which genes of younger evolutionary age and higher genetic diversity contribute significantly more to the transcriptome than in other stages. We refer to this phenomenon as “evolutionary bulge” during plant reproductive development because it differentiates the gametophyte from the sporophyte. We show that multiple, not mutually exclusive, causes may explain the bulge pattern, most prominently reduced tissue complexity of the gametophyte, a varying extent of selection on reproductive traits during gametogenesis as well as differences between male and female tissues. This highlights the importance of plant reproduction for understanding evolutionary forces determining the relationship of genomic and phenotypic variation in plants

    Effect of Preheating on the Permeability of Neonatal Rat Stratum Corneum to Alkanols

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    We heated flat sheets of neonatal rat stratum corneum for various times at temperatures between 40 and 90°C before determining the permeability coefficient (Kp) of propanol and/or hexanol from water. Below 70°C, Kp remained constant; at 75°C, Kp increased linearly with exposure time; at 80°C and above, there was a large increase in under 2 h, with no further increase on longer heating. There was a 15-fold increase in 6-h Kp between 70°C and 80°C, values being constant above 80°C but at a figure less than for lipid-extracted stratum corneum. Thermal analysis showed that the increase in Kp corresponds to changes in the 80°C lipid endotherm, suggesting that the increased Kp is due to a disordering of the lipid structures. The effect of treating preheated stratum corneum with dimethylsulfoxide (DMSO) vapor for 16h was also studied. Below 70°C, Kp was increased five-fold, but between 70 and 80°C this difference was eliminated, so that above 80°C the Kp was the same as with heat treatment alone. We concluded that both heat and DMSO affect the lipid structures of stratum corneum. DMSO produced a small, reversible structural change, while the effect of heat is irreversible and produces a greater degree of disorder in the lipid structures, but the lipid still contributed to the barrier effect of stratum corneum

    Rice breeding for salt tolerance

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    Human exploitation of earth’s resources is leading to new problems day by day and hence newer methods are devised to overcome the same. One such case is breeding for abiotic stress, utilizing even non arable land, to feed the ever increasing population. A major stress leading to yield loss can be due to inland and coastal salinity. Rice is the most important cereal crop which feeds humans on earth. This review tries to analyse the efforts of breeders in minimising the effects of salt stress on the yield of rice crop
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