366 research outputs found

    A portable L-band voice transceiver for satellite communication

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    A portable L-band voice transceiver was developed as a feasibility model and can provide a half-duplex voice link to another terminal via the L-band transponder on the Applications Technology Satellite, ATS-6. The narrow band FM transceiver utilizes commercial subsystems including a UHF transceiver, provides an RF output power of 20 watts, weights less than 25 lbs., is housed in a plastic briefcase, can be powered by an automobile electrical system, and has been successfully operated with ATS-6 on numerous occasions. Design considerations and operation of the transceiver are described, along with alignment and testing procedures, packaging and cost considerations, subsystem performance requirements and overall transceiver performance characteristics

    Traveling-wave tube circuit simplifies microwave relay

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    Circuit with a sawtooth-modulated traveling-wave tube, which acts as a frequency converter and as an amplifier, simplifies microwave transmission. Lower power losses and reduced size and weight are also realized in this circuit

    Efektivitas Limbah Cengkih dalam Menekan Perkembangan In Vitro Sclerotium rolfsii, Jamur Penyebab Damping Off Kacang Tanah

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    Various problems have caused the decline in peanut production, among others the low resistance of peanut plants to various diseases. One of the obstacles in peanut production is the attack of plant diseases, such as the fungus Sclerotium rolfsii Sacc. The use of plant-based insecticides can be an alternative to disease control in peanuts. This study aimed to obtain the appropriate and effective dose of clove leaves and flower stalks in suppressing the in vitro growth of the fungus S. rolfsii Sacc causing damping off in peanuts, and to test the effectiveness of clove leaves and flower stalks on the formation of sklerotia of the fungus. This study used ‘tuni’ clove powder from Waai Village, Salahutu District. This experimental study employed a completely randomized design (CRD) with 8 treatments and 3 replications. The results showed that the growth of the fungus S. rolfsii Sacc. was inhibited by clove flower stalk powder at a dose of 1.5 g per100 mL of PDA, which was indicated by the number of sklerotia formed of 13.67% and propagule weight of 0.12 g, followed by a dose of clove leaf powder of 1.5 g per100 mL PDA, with amount of sklerotia formed of 27.33% and propagule weight of 0.17 g. These results were statistically shown on the parameters: colony diameter, Sklerotia formation time, number of Sklerotia, and weight of propagules. Keywords: Clove powder, dosage, in vitro, Sclerotium rolfsii Sacc.   ABSTRAK Berbagai masalah telah menyebabkan turunnya produksi kacang tanah, diantaranya masih rendahnya ketahanan tanaman kacang tanah terhadap berbagai penyakit. Salah satu kendala dalam produksi kacang tanah adalah serangan penyakit tanaman, seperti jamur Sclerotium rolfsii Sacc. Penggunaan insektisida nabati dapat menjadi alternatif pengendalian penyakit pada kacang tanah. Penelitian ini bertujuan untuk memperoleh dosis daun dan tangkai bunga cengkih yang tepat dan efektif dalam menekan pertumbuhan jamur S. rolfsii Sacc penyebab damping off pada kacang tanah secara in vitro, serta menguji efektifitas daun dan tangkai bunga cengkih terhadap pembentukan sklerotia jamur. Penelitian ini menggunakan bubuk cengkih tuni, dari Desa Waai, Kecamatan Salahutu. Penelitian eksperimental ini menggunakan Rancangan Acak Lengkap (RAL) dengan 8 perlakuan dan 3 ulangan. Hasil penelitian menunjukkan bahwa pertumbuhan jamur S. rolfsii Sacc. terhambat oleh bubuk tangkai bunga cengkih pada dosis 1,5 g per 100 mL PDA yang ditunjukan oleh jumlah sklerotia terbentuk 13,67% dan berat propagul 0,12 g dan diikuti oleh dosis bubuk daun cengkih 1,5 g per 100 mL PDA, dengan jumlah sklerotia 27,33% dan berat propagul 0,17 g. Hasil ini secara statistik ditunjukkan pada parameter: diameter koloni, waktu terbentuk sklerotia, jumlah sklerotia, dan berat propagul. Kata kunci: bubuk cengkih, dosis, in vitro, Sclerotium rolfsii Sacc

    Mixing device for generating simple chromatographic gradients

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    A linear gradient device consisting of two concentric reservoirs of equal cross-sectional area, in which the initial and limiting eluent solutions are maintained in hydrostatic equilibrium, may be constructed from several combinations of commercial acrylic resin cylinders. By the use of nesting cylinders, the areas of the reservoirs may be reduced independently, allowing an assortment of nonlinear gradients to be produced by simple adjustment of the area ratio of the two reservoirs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31971/1/0000013.pd

    Design, synthesis and biological evaluation of novel DNA gyrase Inhibitors and their siderophore mimic conjugates

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    Bacterial DNA gyrase is an important target for the development of novel antibacterial drugs, which are urgently needed because of high level of antibiotic resistance worldwide. We designed and synthesized new 4,5,6,7-tetrahydrobenzo[d]thiazole-based DNA gyrase B inhibitors and their conjugates with siderophore mimics, which were introduced to increase the uptake of inhibitors into the bacterial cytoplasm. The most potent conjugate 34 had an IC50 of 58 nM against Escherichia coli DNA gyrase and displayed MIC of 14 mu g/mL against E. coli.tolC strain. Only minor improvements in the antibacterial activities against wild-type E. coli in low-iron conditions were seen for DNA gyrase inhibitor - siderophore mimic conjugates.Peer reviewe

    Implementation of drift velocities and currents in SOLEDGE2D-EIRENE

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    International audienceIn order to improve cross-field transport description, drifts and currents have been implemented in SOLEDGE2D-EIRENE. The derivation of an equation for the electric potential is recalled. The resolution of current equation is tested in a simple slab case. WEST divertor simulations in forward-B and reverse-B fields are also discussed. A significant increase of ExB shear is observed in the forward-B configuration that could explain a favorable L-H transition in this case

    An optimised series of substituted N-phenylpyrrolamides as DNA gyrase B inhibitors

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    ATP competitive inhibitors of DNA gyrase and topoisomerase IV have great therapeutic potential, but none of the described synthetic compounds has so far reached the market. To optimise the activities and physicochemical properties of our previously reported N-phenylpyrrolamide inhibitors, we have synthesized an improved, chemically variegated selection of compounds and evaluated them against DNA gyrase and topoisomerase IV enzymes, and against selected Gram-positive and Gram-negative bacteria. The most potent compound displayed IC50 values of 6.9 nM against Escherichia coli DNA gyrase and 960 nM against Staphylococcus aureus topoisomerase IV. Several compounds displayed minimum inhibitory concentrations (MICs) against Gram-positive strains in the 1-50 mu M range, one of which inhibited the growth of Enterococcus faecalis, Enterococcus faecium, S. aureus and Streptococcus pyogenes with MIC values of 1.56 mu M, 1.56 mu M, 0.78 mu M and 0.72 mu M, respectively. This compound has been investigated further on methicillin-resistant S. aureus (MRSA) and on ciprofloxacin non-susceptible and extremely drug resistant strain of S. aureus (MRSA VISA). It exhibited the MIC value of 2.5 mu M on both strains, and MIC value of 32 mu M against MRSA in the presence of inactivated human blood serum. Further studies are needed to confirm its mode of action. (C) 2019 Elsevier Masson SAS. All rights reserved.Peer reviewe

    Second generation 4,5,6,7-tetrahydrobenzo[d]thiazoles as novel DNA gyrase inhibitors

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    Aim: DNA gyrase and topoisomerase IV are essential bacterial enzymes, and in the fight against bacterial resistance, they are important targets for the development of novel antibacterial drugs. Results: Building from our first generation of 4,5,6,7-tetrahydrobenzo[d]thiazole-based DNA gyrase inhibitors, we designed and prepared an optimized series of analogs that show improved inhibition of DNA gyrase and topoisomerase IV from Staphylococcus aureus and Escherichia coli, with IC50 values in the nanomolar range. Importantly, these inhibitors also show improved antibacterial activity against Gram-positive strains. Conclusion: The most promising inhibitor, 29, is active against Enterococcus faecalis, Enterococcus faecium and S. aureus wild-type and resistant strains, with minimum inhibitory concentrations between 4 and 8 mu g/ml, which represents good starting point for development of novel antibacterials. Graphical abstractPeer reviewe
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