Search results for " Stab"
showing 10 items of 1773 documents
Copper-hydride nanoclusters with enhanced stability by N-heterocyclic carbenes
2021
AbstractCopper-hydrides have been intensively studied for a long time due to their utilization in a variety of technologically important chemical transformations. Nevertheless, poor stability of the species severely hinders its isolation, storage and operation, which is worse for nano-sized ones. We report here an unprecedented strategy to access to ultrastable copper-hydride nanoclusters (NCs), namely, using bidentate N-heterocyclic carbenes as stabilizing ligands in addition to thiolates. In this work, a simple synthetic protocol was developed to synthesize the first large copper-hydride nanoclusters (NCs) stabilized by N-heterocyclic carbenes (NHCs). The NC, with the formula of Cu31(RS)2…
Robust H<inf>&#x221E;</inf> control of Markovian jump systems with mixed time delays
2010
In this paper, the problem of stability analysis and control synthesis for Markovian jump linear systems with time delays and norm-bounded uncertainties is studied. The model under consideration consists of different time-invariant discrete, neutral and distributed delays. Delay-dependent sufficient conditions for the design of a mode-dependent delayed state feedback H ∞ control are given in terms of linear matrix inequalities (LMIs). A controller which guarantees stochastic stability and a prescribed level of H ∞ performance for the closed-loop system is then developed. A Lyapunov-Krasovskii functional (LKF) method underlies the control design. A numerical example with simulation results i…
О проблеме Гарднера для систем управления фазовой автоподстройкой частоты
2019
This report shows the possibilities of solving the Gardner problem of determining the lock-in range for multidimensional phase-locked loops systems. The development of analogs of classical stability criteria for the cylindrical phase space made it possible to obtain analytical estimates of the lock-in range for third-order system. peerReviewed
Coexistence of hidden attractors and multistability in counterexamples to the Kalman conjecture
2019
The Aizerman and Kalman conjectures played an important role in the theory of global stability for control systems and set two directions for its further development – the search and formulation of sufficient stability conditions, as well as the construction of counterexamples for these conjectures. From the computational perspective the latter problem is nontrivial, since the oscillations in counterexamples are hidden, i.e. their basin of attraction does not intersect with a small neighborhood of an equilibrium. Numerical calculation of initial data of such oscillations for their visualization is a challenging problem. Up to now all known counterexamples to the Kalman conjecture were const…
Absolute quantification of noncoding RNA by microscale thermophoresis
2019
Abstract Accurate quantification of the copy numbers of noncoding RNA has recently emerged as an urgent problem, with impact on fields such as RNA modification research, tissue differentiation, and others. Herein, we present a hybridization‐based approach that uses microscale thermophoresis (MST) as a very fast and highly precise readout to quantify, for example, single tRNA species with a turnaround time of about one hour. We developed MST to quantify the effect of tRNA toxins and of heat stress and RNA modification on single tRNA species. A comparative analysis also revealed significant differences to RNA‐Seq‐based quantification approaches, strongly suggesting a bias due to tRNA modifica…
Modificētas Lopbarības pupiņas raibuma vīrusam līdzīgās daļiņas vakcīnu konstruēšanai
2018
Maģistra darba mērķis ir izveidot CCMV CP VLP konstrukcijas E.coli, kas paredzētas efektīvākai ķīmisko epitopu pievienošanai uz VLP virsmas un lielākai daļiņu stabilitātei. Maģistra darbs izstrādāts no 2016. gada septembra līdz 2018. gada maijam Latvijas Biomedicīnas pētījumu un studiju centrā, Augu virisoloģijas laboratorijā Dr. biol. Andra Zeltiņa un Dr. biol. Inas Baļķes vadībā. Pētījuma objekts ir lopbarības pupiņas raibumu vīruss – CCMV. Maģistra darba laikā tika izveidotas divpadsmit CCMV CP ekspresijas konstrukcijas – pET42-CCMV-G3SKG3, pET4-CCMV-G3SKG3-Ntt830, pET42-CCMV-G3SKG3-Ctt830, pET42-CCMV-SS, pET42-CCMV-Ntt830-SS, pET42-CCMV-Ctt830-SS, pET42-∆24CCMV-SS, pET42-∆24CCMV-Ntt830-…
A library of monoalkenylsilsesquioxanes as potential comonomers for synthesis of hybrid materials
2018
In this paper we demonstrate a facile and efficient synthesis of monoalkenylsubstituted POSS compounds, i.e., R7(Si8O12)-alkenyl and R7(Si8O12)(OSiMe2)-alkenyl with a functional alkenyl group of chain length (from vinyl to dec-9-enyl, with or without additional –OSiMe2– spacer between the silsesquioxane core and alkenyl moiety) and with five types of inert groups (Et, iBu, iOc, Cy, Ph) at the POSS core. These compounds constitute a library of monosubstituted POSS systems, including thorough spectroscopic and thermal characteristics. These findings could be especially useful for material chemists applying the compounds as modifiers or comonomers for copolymerization reaction, e.g., with olef…
Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites
2017
The decomposition behaviours of composites made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and sisal were assessed in terms of thermal stability and decomposition kinetics, under inert and oxidative conditions, by means of multi-rate linear non-isothermal thermogravimetric experiments. A statistical design of experiments was applied to study the influence of the addition of sisal (0-10-20-30%wt), the presence coupling agent (Yes/No) and the applied conditions of work (inert or oxidative). An improvement of the thermal and thermo-oxidative stability of PHBV with the addition of sisal was observed for all cases. An accurate methodology based on iso-conversional methods was applied…
Latvijas rūpniecībai aktuālu farmaceitiski aktīvo vielu kristālsolvāti
2013
ANOTĀCIJA Promocijas darbs veltīts Latvijas tautsaimniecībai aktuālu farmaceitiski aktīvo vielu (FAV) izpētei. Veikti apskatīto vielu kristālsolvātu meklējumi un iegūtas līdz šim neaprakstītas vielu kristāliskās formas. Novērtēta iegūto formu stabilitāte iegūšanas, ražošanas un uzglabāšanas apstākļos. Atsevišķām FAV veikta struktūras noteikšana, gan izmantojot pulvera rentgendifraktometriju, gan monokristālu rentgendifraktometriju. Iegūtie rezultāti ir aktuāli zāļu ražotājiem, kā arī tiem ir zinātniska nozīme no FAV īpašību apzināšanas un metožu attīstības viedokļa. Atslēgas vārdi: kristālsolvāti, vielas stāvokļa diagramma, nestehiometriskie solvāti, vielu termodinamiskā stabilitāte, fāžu p…
LCA of Different Construction Choices for a Double-Track Railway Line for Sustainability Evaluations
2023
The international commitment to achieve carbon neutrality in the next few decades has oriented human activities towards the preservation of natural and non-renewable resources. In this context, a great research effort has been devoted to the search for sustainable solutions for the infrastructure construction sector, based on a thorough assessment of the environmental impact (EI). In this regards, Life Cycle Assessment (LCA) is considered one of the main components of Environmental Impact Assessment (EIA) and, for a comprehensive analysis, all the costs incurred by stakeholders during the useful life of the infrastructure should also be taken into account, applying the Life Cycle Cost (LCC)…