DEVELOPMENT OF A MODEL FOR THE PRODUCTION OF METAL-POWDER COMPOSITIONS BASED ON CO-CR ALLOYS BY ELECTROEROSIVE DISPERSION

Abstract. The main requirement for powders for additive 3d technologies is the spherical shape of theparticles. Such particles are most compactly packed into a certain volume and ensure the "fluidity" of the powder composition in the supply systems of the material with minimal resistance. The wide use of the EED method for processing metal waste into powders for the purpose of their reuse and application in additive technologies is hampered by the lack in the scientific and technical literature of full-fledged information on the effect of the initial composition, regimes and media on the properties of powders and technologies of practical application. Therefore, in order to develop technologies for the reuse of electroerosive powders and to evaluate the effectiveness of their use, complex theoretical and experimental studies are required. The aim of the work was to develop a model for the production of metal powder compositions on the basis of Co-Cr alloys by electroerosive dispersion. Based on the results of the conducted studies, it has been established that the optimum parameters for the process of obtaining powder materials by the method of electroerosive dispersion of butyl alcohol are: capacitance of discharge capacitors 48 μF, voltage on electrodes 100 V, repetition rate of pulses 120 Hz

Suppressed absolute negative conductance and generation of high-frequency radiation in semiconductor superlattices

We show that space-charge instabilities (electric field domains) in semiconductor superlattices are the attribute of absolute negative conductance induced by small constant and large alternating electric fields. We propose the efficient method for suppression of this destructive phenomenon in order to obtain a generation at microwave and THz frequencies in devices operating at room temperature. We theoretically proved that an unbiased superlattice with a moderate doping subjected to a microwave pump field provides a strong gain at third, fifth, seventh, etc. harmonics of the pump frequency in the conditions of suppressed domains.Comment: 8 pages. Development of cond-mat/0503216 . Version 2: Final version, erratum is include

Affinity proteomic dissection of the human nuclear cap-binding complex interactome

A 5',7-methylguanosine cap is a quintessential feature of RNA polymerase II-transcribed RNAs, and a textbook aspect of co-transcriptional RNA processing. The cap is bound by the cap-binding complex (CBC), canonically consisting of nuclear cap-binding proteins 1 and 2 (NCBP1/2). Interest in the CBC has recently renewed due to its participation in RNA-fate decisions via interactions with RNA productive factors as well as with adapters of the degradative RNA exosome. A novel cap-binding protein, NCBP3, was recently proposed to form an alternative CBC together with NCBP1, and to interact with the canonical CBC along with the protein SRRT. The theme of post-transcriptional RNA fate, and how it relates to co-transcriptional ribonucleoprotein assembly, is abundant with complicated, ambiguous, and likely incomplete models. In an effort to clarify the compositions of NCBP1-, 2- and 3-related macromolecular assemblies, we have applied an affinity capture-based interactome screen where the experimental design and data processing have been modified to quantitatively identify interactome differences between targets under a range of experimental conditions. This study generated a comprehensive view of NCBP-protein interactions in the ribonucleoprotein context and demonstrates the potential of our approach to benefit the interpretation of complex biological pathways

Transcriptome analysis reveals novel regulatory mechanisms in a genome-reduced bacterium

© 2014 The Author(s). The avian bacterial pathogen Mycoplasma gallisepticum is a good model for systems studies due to small genome and simplicity of regulatory pathways. In this study, we used RNA-Seq and MS-based proteomics to accurately map coding sequences, transcription start sites (TSSs) and transcript 3′-ends (T3Es). We used obtained data to investigate roles of TSSs and T3Es in stress-induced transcriptional responses. We identified 1061 TSSs at a false discovery rate of 10% and showed that almost all transcription in M. gallisepticum is initiated from classic TATAAT promoters surrounded by A/T-rich sequences. Our analysis revealed the pronounced operon structure complexity: on average, each coding operon has one internal TSS and T3Es in addition to the primary ones. Our transcriptomic approach based on the intervals between the two nearest transcript ends allowed us to identify two classes of T3Es: strong, unregulated, hairpin-containing T3Es and weak, heat shock-regulated, hairpinless T3Es. Comparing gene expression levels under different conditions revealed widespread and divergent transcription regulation in M. gallisepticum. Modeling suggested that the core promoter structure plays an important role in gene expression regulation. We have shown that the heat stress activation of cryptic promoters combined with the hairpinless T3Es suppression leads to widespread, seemingly non-functional transcription

Impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field

We report on the observation and experimental studies of impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field. The terahertz electroluminescence is observed in a wide range of doping levels (at noncompensated donor density from 4.5×10[sup 16] to 3.4×10[sup 18] cm[sup −3]). Spectra of terahertz luminescence and photoconductivity are studied by means of Fourier transform spectrometry. Distinctive features of the spectra can be assigned to intracenter electron transitions between excited and ground states of silicon and oxygen donors and to hot electron transitions to the donor states.Peer reviewe

LINE-1 ORF2p expression is nearly imperceptible in human cancers

Background Long interspersed element-1 (LINE-1, L1) is the major driver of mobile DNA activity in modern humans. When expressed, LINE-1 loci produce bicistronic transcripts encoding two proteins essential for retrotransposition, ORF1p and ORF2p. Many types of human cancers are characterized by L1 promoter hypomethylation, L1 transcription, L1 ORF1p protein expression, and somatic L1 retrotransposition. ORF2p encodes the endonuclease and reverse transcriptase activities required for L1 retrotransposition. Its expression is poorly characterized in human tissues and cell lines. Results We report mass spectrometry-based tumor proteome profiling studies wherein ORF2p eludes detection. To test whether ORF2p could be detected with specific reagents, we developed and validated five rabbit monoclonal antibodies with immunoreactivity for specific epitopes on the protein. These reagents readily detect ectopic ORF2p expressed from bicistronic L1 constructs. However, endogenous ORF2p is not detected in human tumor samples or cell lines by western blot, immunoprecipitation, or immunohistochemistry despite high levels of ORF1p expression. Moreover, we report endogenous ORF1p-associated interactomes, affinity isolated from colorectal cancers, wherein we similarly fail to detect ORF2p. These samples include primary tumors harboring hundreds of somatically acquired L1 insertions. The new data are available via ProteomeXchange with identifier PXD013743. Conclusions Although somatic retrotransposition provides unequivocal genetic evidence for the expression of ORF2p in human cancers, we are unable to directly measure its presence using several standard methods. Experimental systems have previously indicated an unequal stoichiometry between ORF1p and ORF2p, but in vivo, the expression of these two proteins may be more strikingly uncoupled. These findings are consistent with observations that ORF2p is not tolerable for cell growth

Синтез гідразидів 3,5-дибром-2-хлоробензойної кислоти як потенційних протитуберкульозних засобів

Antitubercular drugs are used for a number of decades. In each country where research is conducted strains of mycobacteria that are resistant to one or more drugs have been registered, and it causes tuberculosis with multi-drug resistance (MDR-TB). These strains of M. tuberculosis at least are not sensitive to isoniazid and rifampicin – two most powerful first-line antitubercular drugs. MDR-TB can be treated and cured using the second choice drugs. However, these treatment options are limited and require extensive chemotherapy (the treatment duration is up to two years) with drugs which are of high cost and toxicity. In some cases, a more dangerous drug resistance may develop. Tuberculosis with extensive drug resistance (EDR-TB) is more severe form of MDR-TB caused by bacteria that do not respond to the most effective antitubercular drugs of the second choice with which there are often no any further treatment options for patients. Therefore, the search and development of drugs with the antitubercular activity are important today.Aim. To synthesize and study dibromo-substituted derivatives of ortho-chlorobenzoic acids as potential substances with the antitubercular action.Materials and methods. Hydrazides of 3,5-dibromo-2-chlorobenzoic acid were obtained by two methods – by hydrazinolysis of acid chlorides of the corresponding acids (method 1) and by interaction of 3,5-dibromo-2-chlorobenzoic acid with hydrazines in the presence of carbonyldiimidazole (method 2).Results and discussion. It has been found that the synthesis of hydrazides by method 2 allows obtaining the target compounds with a high yield.Conclusions. According to the literature data the compounds synthesized are promising for the pharmacological screening on the antitubercular activity.Противотуберкулезные лекарственные средства используются в течение целого ряда десятилетий. В каждой стране, где проводятся исследования, зарегистрированы штаммы микобактерий, устойчивые к одному или нескольким препаратам, что приводит к возникновению туберкулеза с множественной лекарственной устойчивостью (МЛУ-ТБ). Эти штаммы M. tuberculosis по меньшей мере не чувствительны к изониазиду и рифампицину – двум самым мощным противотуберкулезным препаратам первого ряда. МЛУ-ТБ можно лечить и излечивать, используя препараты второго ряда. Однако такие варианты лечения ограничены и требуют проведения экстенсивной химиотерапии (лечение продолжительностью до двух лет) препаратами, которые отличаются высокой стоимостью и токсичностью. В некоторых случаях может развиваться более опасная лекарственная устойчивость. Туберкулез с широкой лекарственной устойчивостью (ШЛУ-ТБ) является более тяжелой формой МЛУ-ТБ, вызываемой бактериями, которые не реагируют на самые эффективные противотуберкулезные препараты второго ряда, при которых у пациентов нередко не остается никаких дальнейших вариантов лечения. Поэтому поиск и создание лекарственных средств с противотуберкулезной активностью является актуальным.Целью данной работы является синтез и исследование дибромзамещённых производных орто-хлорбензойных кислот как потенциальных субстанций с противотуберкулезным действием.Материалы и методы. Гидразиды 3,5 дибром-2-хлорбензойной кислоты получали двумя способами – гидразинолизом хлорангидридов соответствующих кислот (способ 1) и взаимодействием 3,5-дибром-2-хлорбензойной кислоты с гидразином в присутствии карбонилдиимидазола (способ 2).Результаты и их обсуждение. Установлено, что синтез гидразидов по способу 2 позволяет получить целевые соединения с большим выходом.Выводы. Согласно данным литературы синтезированные соединения являются перспективными веществами для фармакологических исследований на противотуберкулезную активность.Протитуберкульозні лікарські засоби використовуються впродовж цілого ряду десятиліть. У кожній країні, де проводяться дослідження, зареєстровані штами мікобактерій, стійкі до одного або декількох препаратів, що зумовлює виникнення туберкульозу з множинною лікарською стійкістю (МЛС-ТБ). Ці штами M. tuberculosis щонайменше не чутливі до ізоніазиду та рифампіцину – двох найпотужніших протитуберкульозних препаратів першого ряду. МЛС-ТБ можна лікувати і виліковувати, використовуючи препарати другого ряду. Однак такі варіанти лікування обмежені і вимагають проведення екстенсивної хіміотерапії (лікування тривалістю до двох років) препаратами, які відрізняються високою вартістю і токсичністю. У деяких випадках може розвиватися більш небезпечна лікарська стійкість. Туберкульоз з широкою лікарською стійкістю (ШЛС-ТБ) є більш важкою формою МЛС-ТБ, що викликається бактеріями, які не реагують на найефективніші протитуберкульозні препарати другого ряду, при яких у пацієнтів нерідко не залишається ніяких подальших варіантів лікування. Тому пошук та створення лікарських засобів з протитуберкульозною активністю є актуальним.Метою даної роботи є синтез і дослідження дибромозаміщених похідних орто-хлоробензойних кислот як потенційних субстанцій з протитуберкульозною дією.Матеріали та методи. Гідразиди 3,5-дибром-2-хлоробензойної кислоти отримували двома способами – гідразинолізом хлорангідридів відповідних кислот (спосіб 1) та взаємодією 3,5-дибром-2-хлоробензойної кислоти з гідразином у присутності карбонілдіімідазолу (спосіб 2).Результати та їх обговорення. Встановлено, що синтез гідразидів способом 2 дозволяє отримати цільові сполуки з більшим виходом. Висновки. Згідно з даними літератури синтезовані сполуки є перспективними речовинами для фармакологічних досліджень на протитуберкульозну активність.