32 research outputs found

    Synthesis of γ-, Ύ-, and Δ-Lactams by Asymmetric Transfer Hydrogenation of N-(tert-Butylsulfinyl)iminoesters

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    Highly enantiomerically enriched Îł- and ÎŽ-lactams have been prepared by a simple and very efficient procedure that involves the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)iminoesters followed by desulfinylation of the nitrogen atom and spontaneous cyclization to the desired lactams during the basic workup procedure. Five- and six-membered ring lactams bearing aromatic, heteroaromatic, and aliphatic substituents have been obtained in very high yields and ee’s up to >99%. A slight modification of the procedure also allowed the preparation of Δ-lactams in good yields and very high enantioselectivities. Both enantiomers of the final lactams could be prepared with equal efficiency by changing the absolute configuration of the sulfinyl chiral auxiliary

    Potencial inseticida de plantas da famĂ­lia Annonaceae

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    Efficacy of Major Plant Extracts/Molecules on Field Insect Pests

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    Insect pests are considered the major hurdle in enhancing the production and productivity of any farming system. The use of conventional synthetic pesticides has led to the emergence of pesticide-resistant insects, environmental pollution, and negative effects on natural enemies, which have caused an ecological imbalance of the predator-prey ratio and human health hazards; therefore, eco-friendly alternative strategies are required. The plant kingdom, a rich repertoire of secondary metabolites, can be tapped as an alternative for insect pest management strategies. A number of plants have been documented to have insecticidal properties against various orders of insects in vitro by acting as antifeedants, repellents, sterilant and oviposition deterrents, etc. However, only a few plant compounds are applicable at the field level or presently commercialised. Here, we have provided an overview of the broad-spectrum insecticidal activity of plant compounds from neem, Annona, Pongamia, and Jatropha. Additionally, the impact of medicinal plants, herbs, spices, and essential oils has been reviewed briefl

    Human Assistive Lower Limb Exoskeleton

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    Exoskeletons have proven to be helpful in assisting humans in major fields such as rehabilitation, military, industries and more. However, even though these exoskeletons provide useful features,most of them fail to reach humans in need due to their high cost. In this paper, we present Human Assistive Lower Limb Exoskeleton (HALEX), a low-cost exoskeleton developed to provide human assistance during gait locomotion. HALEX is a hybrid lower limb exoskeleton which provides enough DOFs to users while locomotion. The paper discusses the development of HALEX, it uses electric motors coupled with self-developed gearbox at hip and knee and uses a passive element that is a tension spring at the ankle joint. Adjustable link lengths allow wearers of different heights and waist sizes to use this exoskeleton with ease. A load carrying structure allowsthe wearer to carry additional weights with reduced efforts. Tests were done to obtain the scale of assistance HALEX provides and the results of the same are discussed
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