Ion Homeostasis Response to Nutrient-Deficiency Stress in Plants

A crucial feature of plant performance is its strong dependence on the availability of essential mineral nutrients, affecting multiple vital functions. Indeed, mineral-nutrient deficiency is one of the major stress factors affecting plant growth and development. Thereby, nitrogen and potassium represent the most abundant mineral contributors, critical for plant survival. While studying plant responses to nutrient deficiency, one should keep in mind that mineral nutrients, along with their specific metabolic roles, are directly involved in maintaining cell ion homeostasis, which relies on a finely tuned equilibrium between cytosolic and vacuolar ion pools. Therefore, in this chapter we briefly summarize the role of the ion homeostasis system in cell responses to environmental deficiency of nitrate and potassium ions. Special attention is paid to the implementation of plant responses via NO3− and K+ root transport and regulation of ion distribution in cell compartments. These responses are strongly dependent on plant species, as well as severity and duration of nutrient deficiency

Analysis of gas dynamics in a single-phase two-channel plasma torch at cold blowing and considering the interaction with the electric arc

This article is devoted to the simulation of cold gas purge and flow taking into account the plasma arc in the channels of a single-phase two-channel high-voltage plasma torch with cylindrical electrodes. The results obtained in the process of modeling made it possible to simplify the model for further modeling, which will result in the distribution of velocities, temperatures and voltage drop on the arc depending on the time

Analysis of gas dynamics in a single-phase two-channel plasma torch at cold blowing and considering the interaction with the electric arc

This article is devoted to the simulation of cold gas purge and flow taking into account the plasma arc in the channels of a single-phase two-channel high-voltage plasma torch with cylindrical electrodes. The results obtained in the process of modeling made it possible to simplify the model for further modeling, which will result in the distribution of velocities, temperatures and voltage drop on the arc depending on the time

Numerical simulation of DC air plasma torch modes and plasma jet instability for thermal spraying technology

The article is dedicated to nonstationary simulation of DC air plasma torch. The mathematical model for the analysis of plasma jet instability is developed. The proposed 2D axisymmetric model demonstrates the physical processes taking place inside and in the outer region of the plasma torch. The influence of the power source parameters and anode geometry on voltage and plasma jet fluctuation is described. Simplified mathematical model is developed in order to assess the effect of the flow behavior on heat transfer processes. The developed model can be used for the design of plasma torches and their operation modes. The results of mathematical model verification are based on experimental studies

Numerical simulation of DC air plasma torch modes and plasma jet instability for thermal spraying technology

The article is dedicated to nonstationary simulation of DC air plasma torch. The mathematical model for the analysis of plasma jet instability is developed. The proposed 2D axisymmetric model demonstrates the physical processes taking place inside and in the outer region of the plasma torch. The influence of the power source parameters and anode geometry on voltage and plasma jet fluctuation is described. Simplified mathematical model is developed in order to assess the effect of the flow behavior on heat transfer processes. The developed model can be used for the design of plasma torches and their operation modes. The results of mathematical model verification are based on experimental studies

Spersonalizowany model stratyfikacji ryzyka do prognozowania zagrażających życiu tachyarytmii komorowych u pacjentów z przewlekłą niewydolnością serca

Background: The development of prognostic factors of life-threatening ventricular tachyarrhythmias (VTA) and sudden cardiac death (SCD) continues to maintain its priority and relevance in cardiology. The development of a method of personalised prognosis based on multifactorial analysis of the risk factors associated with life-threatening heart rhythm disturbances is considered a key research and clinical task. Aim: To design a prognostic and mathematical model to define personalised risk for life-threatening VTA in patients with chronic heart failure (CHF). Methods: The study included 240 patients with CHF (mean-age of 50.5 ± 12.1 years; left ventricular ejection fraction 32.8 ± 10.9%; follow-up period 36.8 ± 5.7 months). The participants received basic therapy for heart failure. The elec­trocardiogram (ECG) markers of myocardial electrical instability were assessed including microvolt T-wave alternans, heart rate turbulence, heart rate deceleration, and QT dispersion. Additionally, echocardiography and Holter monitoring (HM) were performed. The cardiovascular events were considered as primary endpoints, including SCD, paroxysmal ventricular tachycardia/ventricular fibrillation (VT/VF) based on HM-ECG data, and data obtained from implantable device interrogation (CRT-D, ICD) as well as appropriated shocks. Results: During the follow-up period, 66 (27.5%) subjects with CHF showed adverse arrhythmic events, including nine SCD events and 57 VTAs. Data from a stepwise discriminant analysis of cumulative ECG-markers of myocardial electrical instability were used to make a mathematical model of preliminary VTA risk stratification. Uni- and multivariate Cox logistic regression analysis were performed to define an individualised risk stratification model of SCD/VTA. A binary logistic regression model demonstrated a high prognostic significance of discriminant function with a classification sensitivity of 80.8% and specificity of 99.1% (F = 31.2; c2 = 143.2; p < 0.0001). Conclusions: The method of personalised risk stratification using Cox logistic regression allows correct classification of more than 93.9% of CHF cases. A robust body of evidence concerning logistic regression prognostic significance to define VTA risk allows inclusion of this method into the algorithm of subsequent control and selection of the optimal treatment modality to treat patients with CHF.Wstęp: Określenie czynników prognostycznych zagrażających życiu tachyarytmii komorowych (VTA) i nagłego zgonu sercowego (SCD) wciąż pozostaje priorytetowym celem w kardiologii. Opracowanie metod spersonalizowanego prognozowania na podstawie analizy wieloczynnikowej czynników ryzyka związanych z zagrażającymi życiu zaburzeniami rytmu uznaje się obecnie za zagadnienie o podstawowym znaczeniu zarówno z naukowego, jak i klinicznego punktu widzenia. Cel: Celem badania było zaprojektowanie prognostycznego i matematycznego modelu służącego do definiowania spersona­lizowanego ryzyka zagrażających życiu VTA u pacjentów z przewlekłą niewydolnością serca (CHF). Metody: Badanie obejmowało 240 chorych z CHF (średnie wartości: wiek 50,5 ± 12,1 roku; frakcja wyrzutowa lewej komory 32,8 ± 10,9%; okres obserwacji 36,8 ± 5,7 miesiąca). Chorzy byli poddani podstawowemu leczeniu niewydolności serca. Oceniano wskaźniki elektrokardiograficzne (EKG) niestabilności elektrycznej miokardium, w tym zmienność kształtu i wysokości załamka T (microvolt T-wave alternans), zaburzenia rytmu serca, deceleracje rytmu serca i dyspersję odstępu QT. Ponadto chorych poddano badaniu echokardiograficznemu i monitorowaniu holterowskiemu EKG. Punktami końcowymi badania były zdarzenia sercowo-naczyniowe, w tym SCD, napadowy częstoskurcz komorowy/napadowe migotanie komór (VT/VF) stwierdzone w zapisie holterowskiego EKG oraz odpowiednie dane pobrane z wszczepionego urządzenia (CRT-D, ICD), a także historia podanych wyładowań. Wyniki: W okresie obserwacji u 66 (27,5%) osób z CHF wystąpiły zdarzenia niepożądane w postaci zaburzeń rytmu, w tym 9 przypadków SCD i 57 epizodów VTA. Dane uzyskane w krokowej analizie dyskryminacyjnej skumulowanych wskaźników EKG niestabilności elektrycznej miokardium wykorzystano do opracowania matematycznego modelu wstępnej stratyfikacji ryzyka VTA. Ponadto przeprowadzono jedno- i wieloczynnikową analizę regresji logistycznej Coxa w celu określenia modelu zindywidualizowanej stratyfikacji ryzyka SCD/VTA. Stosując binarny model regresji logistycznej, wykazano wysoką istotność prognostyczną funkcji dyskryminacyjnej tej metody, a czułość i swoistość klasyfikacji wynosiły odpowiednio 80,8% i 99,1% (F = 31; c2 = 143,2; p < 0,0001). Wnioski: Metoda spersonalizowanej klasyfikacji ryzyka z zastosowaniem modelu regresji logistycznej Coxa pozwala prawidłowo sklasyfikować ponad 93,9% przypadków CHF. Liczne dane naukowe potwierdzające skuteczność prognozowania ryzyka VTA przy użyciu metody regresji logistycznej uzasadnia włączenie tej metody do algorytmu monitorowania i wyboru właściwego sposobu leczenia u pacjentów z CHF

Metabolic responses to zinc stress in Amaranthus caudatus roots and leaves

During the last decades, pollution with heavy metals (HM) became an important stress factor for plants. However, due to their biochemical plasticity, plants can adjust their metabolism to ensure survival under changing environmental conditions. In the most comprehensive and straightforward way these metabolic shifts can be addressed by the untargeted mass spectrometry-based metabolomics approach. However, although this methodology is well-established for cadmium-related responses, comprehensive metabolomics studies of Zn-induced metabolic shifts are still missing. Therefore, here we propose, to the best of our knowledge, the first gas chromatography-mass spectrometry (GC-MS)-based metabolomics study of Zn2+-induced stress responses in amaranth. Thereby, 419 metabolites could be annotated and 144 of them were unambiguously identified. The metabolic shifts were organ-specific and more pronounced in roots. The most of the responsive metabolites were up-regulated and dominated with sugars and, to a lesser extent, TCA-related organic acids (a total of 51 and 41, respectively) that could be attributed to their involvement in osmoregulation, ROS scavenging and complexation of Zn2+ ions. Galactose was the most Zn2+-responsive root sugar that indicated its possible role in Zn2+ ion binding to the root cell walls. A 59-fold increase of gluconate content in roots clearly indicated its involvement in Zn2+ chelation. A high Zn2+–induced up-regulation of salicylic acid in roots and shoots suggested a key role of this hormone in the activation of Zn2+ stress tolerance mechanisms. Thus, our study provides the first insight in the general trends in Zn-induced biochemical rearrangements and main adaptive metabolic shifts in A. caudatus plants

Analysis of the Characteristics of a Biharmonic Oscillator with Two Synchronous Modes

The paper investigates the influence of the coupling coefficient of the double-loop filter forming a biharmonic oscillator on the quality factor and resonant impedance of the input impedance at the resonant frequencies of the double-loop filter. The resonant frequencies of the filter are exactly multiples of 2. In this paper show numerical results that simplify the choice of filter parameters to provide conditions for selfexcitation of two oscillations at exactly multiples of frequencies. Two synchronous modes allow to create a generator with compensation for fluctuations in the reactive component of the output impedance of the active element, which increase the phase noise of the oscillator

Ninety-one species of lichens and allied fungi new to Latvia with a list of additional records from Kurzeme

The results of lichenological excursions of the 19th Symposium of Baltic Mycologists and Lichenologists (BMLS) in Latvia, Kurzeme region, 22–26 September 2014, are reported. A list of 290 species is presented, of which 238 are lichenized, 43 lichen-inhabiting, and nine saprotrophic fungi: ninety-one species are new to Latvia, twelve of which (Caloplaca duplicata, Cresporhaphis wienkampii, Ellisembia lichenicola, Gallowayella weberi, Gregorella humida, Lichenochora weillii, Parmelia serrana, Polycauliona phlogina, Reconditella physconiarum, Stictis brunnescens, Thelocarpon superellum, and Verrucaria tectorum) are also new for the Baltic States. Athallia alnetorum is reported here for the first time in northern Europe. The presence of Ochrolechia androgyna s. str., Athallia holocarpa and A. pyracea is confirmed for Latvia, and Parmelia submontana is reported as a new host for Homostegia piggotii

Direct Observation of Aminoglycoside–RNA Binding by Localized Surface Plasmon Resonance Spectroscopy

RNA is involved in fundamental biological functions when bacterial pathogens replicate. Identifying and studying small molecules that can interact with bacterial RNA and interrupt cellular activities is a promising path for drug design. Aminoglycoside (AMG) antibiotics, prominent natural products that recognize RNA specifically, exert their biological functions by binding to prokaryotic ribosomal RNA and interfering with protein translation, ultimately resulting in bacterial cell death. The decoding site, a small internal loop within the 16S rRNA, is the molecular target for the AMG antibiotics. The specificity of neomycin B, a highly potent AMG antibiotic, to the ribosomal decoding RNA site, was previously studied by observing AMG–RNA complexes in solution. Here, we study this interaction using localized surface plasmon resonance (LSPR) transducers comprising gold island films prepared by evaporation on glass and annealing. Small molecule AMG receptors were immobilized on the Au islands via polyethylene glycol (PEG)-thiol linkers, and the interaction with target RNA in solution was studied by monitoring the change in the LSPR optical response upon binding. The results show high-affinity binding of neomycin to 27-nucleotide model A-site RNA sequence in the nanomolar range, while no specific binding is observed for synthetic RNA oligomers (e.g., poly-U). The impact of specific base substitutions in the A-site RNA constructs on binding affinity and selectivity is determined quantitatively. It is concluded that LSPR is a powerful tool for providing molecular insight into small molecule–RNA interactions and for the design and screening of selective antimicrobial drugs