513 research outputs found
Tetrazine- and trans-cyclooctene-functionalised polypept(o)ides for fast bioorthogonal tetrazine ligation
The inverse electron demand Diets-Alder (IEDDA) reaction-initiated ligation between 1,2,4,5-tetra-zines (Tz) and trans-cyclooctenes (TCO) is one of the fastest bioorthogonal reactions known today and is therefore increasingly used for in vivo click chemistry. Described herein is the synthesis of Tz- and TCO-functionalised polypeptides, polypeptoids and polypeptide-block-polypeptoids (polypept(o) ides) by ring-opening polymerisation of the corresponding N-carboxyanhydrides using Tz- or TCO-functional amine initiators. Despite the reactivity of tetrazines, polymers with low dispersity and high end group integrity can be obtained as observed by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Amphiphilic Tz-functionalised block copolypept(o)ides were used to prepare polymeric micelles and organic colloids by miniemulsion techniques, which may find an application as clearing agents in pretargeted nuclear imaging and therapy using efficient in vivo click chemistry. The reaction kinetics of the tetrazine ligation using the synthesised polymers and the accessibility of the Tz groups on the polymeric nanoparticles were evaluated using UV Vis and fluorescence correlation spectroscopy (FCS), and second-order rate constants were determined by stopped-flow spectrophotometry ensuring quantitative conversions in seconds at sub-millimolar concentrations (10-30 s).Drug Delivery Technolog
Mechanical properties of geopolymer concretes reinforced with waste steel fibers
The article presents the research that try to determinate the possibilities of utilization the waste came from used tires to create the composites based on geopolymer matrix. The tire is multicomponent construction. It mainly consists of elastomer (rubber), metal and textile fibres such called textile cord. A lot of components causes difficulties in the tire recycling process. The main aim of the research was determinate the possibilities of recycling the waste steel from used tires in geopolymer composites and develop the eco-friendly material for construction industry. The matrix based on fly ash from power station located in city named Skawina (Poland) and fine sand at a ratio of 1:1. The process of activation was made by 10M sodium hydroxide solution combined with the sodium silicate solution. In order to manufacture these composites the addition of 2% and 3.5% of waste steel fibres by mass was applied. Also specimen without steel fiber reinforcement were made to get reference specimens. The waste steel fibres came from recycling company from Argentina - 'Regomax'. The specimens were prepared according to the methodology described in the standard EN 12390-1. The research methods used were: microstructure research, tensile strength and compressive strength tests as well as analysis of breakthroughs.Fil: Gailitis, R. Riga Technical University; LetoniaFil: Korniejenko, K. Cracow University Of Technology; PoloniaFil: Lach, M. Riga Technical University; LetoniaFil: Sliseris, J. Riga Technical University; LetoniaFil: Moran, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Rodriguez, Exequiel Santos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Mikula, J. Cracow University Of Technology; Poloni
Stability and consistency of the semi-implicit co-volume scheme for regularized mean curvature flow equation in level set formulation
Space-Variant Gabor Decomposition for Filtering 3D Medical Images
This is an experimental paper in which we introduce the possibility to analyze and to synthesize 3D medical images by using multivariate Gabor frames with Gaussian windows. Our purpose is to apply a space-variant filter-like operation in the space-frequency domain to correct medical images corrupted by different types of acquisitions errors. The Gabor frames are constructed with Gaussian windows sampled on non-separable lattices for a better packing of the space-frequency plane. An implementable solution for 3D-Gabor frames with non-separable lattice is given and numerical tests on simulated data are presented.Austrian Science Fund (FWF) P2751
ANALYSIS SLAGGING OF HEATING SURFACE OF THE GAS GENERATOR IGCC
The paper presents a brief overview of the mechanisms of formation of deposits on the surfaces of the gas generator, on the experience of energy steam boilers.В работе изложен краткий обзор механизмов образований отложений на поверхностях газогенератора, на опыте энергетических паровых котлов
DESIGN FEATURES OF PLATE GAS-GAS HEAT EXCHANGER AT HIGH MEDIA PRESSURES
In the work, the design of plate heat exchangers was considered, and various schemes of the movement of media in it were given.В работе рассмотрены конструкции пластинчатых теплообменных аппаратов, а также приведены различные схемы движения сред в нем
Comprehensive Analysis of the Palindromic Motif TCTCGCGAGA: A Regulatory Element of the HNRNPK Promoter
Definitive identification of promoters, their cis-regulatory motifs, and their trans-acting proteins requires experimental analysis. To define the HNRNPK promoter and its cognate DNA–protein interactions, we performed a comprehensive study combining experimental approaches, including luciferase reporter gene assays, chromatin immunoprecipitations (ChIP), electrophoretic mobility shift assays (EMSA), and mass spectrometry (MS). We discovered that out of the four potential HNRNPK promoters tested, the one containing the palindromic motif TCTCGCGAGA exhibited the highest activity in a reporter system assay. Although further EMSA and MS analyses, performed to uncover the identity of the palindrome-binding transcription factor, did identify a complex of DNA-binding proteins, neither method unambiguously identified the pertinent direct trans-acting protein(s). ChIP revealed similar chromatin states at the promoters with the palindromic motif and at housekeeping gene promoters. A ChIP survey showed significantly higher recruitment of PARP1, a protein identified by MS as ubiquitously attached to DNA probes, within heterochromatin sites. Computational analyses indicated that this palindrome displays features that mark nucleosome boundaries, causing the surrounding DNA landscape to be constitutively open. Our strategy of diverse approaches facilitated the direct characterization of various molecular properties of HNRNPK promoter bearing the palindromic motif TCTCGCGAGA, despite the obstacles that accompany in vitro methods
DEVELOPMENT OF EXTERNAL ELEMENTS TO REDUCE WEAR ON THE GAS COOLER FOR THE SHELL IGCC PROCESS
Ранее проводилось CFD-моделирование эрозионного износа входных поверхностей конвективного газоохладителя (ГО) ПГУ-ВЦГ по схеме Shell. Были выполнены три варианта расчетов с различной конфигурацией обтекателя. По результатам было установлено, что установка обтекателя улучшает распределение потока газа по каналам ГО, однако требуется зона, в которой поток успеет перераспределиться перед входом в каналы ГО. Для этого планируется увеличить высоту установки обтекателя и провести оптимизацию этого параметра. Также для уменьшения износа будет рассмотрена установка фальш-рядов.Numerical modeling of the erosion wear of the convection gas cooler input surfaces for the combined cycle process (IGCC) with Shell integrated gasification was performed using CFD software. There are 3 calculations with different bluff body configurations. Based on the results obtained, it was concluded that it is advisable to install a fairing to reduce erosive wear on the surfaces of the gas cooler heat exchanger. To do this, we plan to increase the height of the fairing and optimize this parameter. Also, to reduce wear, the installation of false rows will be considered
A proposal for a coordinated effort for the determination of brainwide neuroanatomical connectivity in model organisms at a mesoscopic scale
In this era of complete genomes, our knowledge of neuroanatomical circuitry
remains surprisingly sparse. Such knowledge is however critical both for basic
and clinical research into brain function. Here we advocate for a concerted
effort to fill this gap, through systematic, experimental mapping of neural
circuits at a mesoscopic scale of resolution suitable for comprehensive,
brain-wide coverage, using injections of tracers or viral vectors. We detail
the scientific and medical rationale and briefly review existing knowledge and
experimental techniques. We define a set of desiderata, including brain-wide
coverage; validated and extensible experimental techniques suitable for
standardization and automation; centralized, open access data repository;
compatibility with existing resources, and tractability with current
informatics technology. We discuss a hypothetical but tractable plan for mouse,
additional efforts for the macaque, and technique development for human. We
estimate that the mouse connectivity project could be completed within five
years with a comparatively modest budget.Comment: 41 page
Free-energy distribution of binary protein-protein binding suggests cross-species interactome differences
Major advances in large-scale yeast two hybrid (Y2H) screening have provided
a global view of binary protein-protein interactions across species as
dissimilar as human, yeast, and bacteria. Remarkably, these analyses have
revealed that all species studied have a degree distribution of protein-protein
binding that is approximately scale-free (varies as a power law) even though
their evolutionary divergence times differ by billions of years. The universal
power-law shows only the surface of the rich information harbored by these
high-throughput data. We develop a detailed mathematical model of the
protein-protein interaction network based on association free energy, the
biochemical quantity that determines protein-protein interaction strength. This
model reproduces the degree distribution of all of the large-scale Y2H data
sets available and allows us to extract the distribution of free energy, the
likelihood that a pair of proteins of a given species will bind. We find that
across-species interactomes have significant differences that reflect the
strengths of the protein-protein interaction. Our results identify a global
evolutionary shift: more evolved organisms have weaker binary protein-protein
binding. This result is consistent with the evolution of increased protein
unfoldedness and challenges the dogma that only specific protein-protein
interactions can be biologically functional..Comment: 31 pages, 5 figure
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