Current-induced ion concentration polarization at a perfect ion-exchange patch in an infinite insulating wall

This research examines, theoretically, the ion concentration polarization, ion fluxes, and electrostatic fields near an ion- exchange patch in the wall of an electrified fluidic channel. These phenomena are important in related microfluidic ion- preconcentration systems. Under an electric field, counter ions enter the ion-exchange patch at one side and leave at the other, with salt depletion occurring near the entrance and accumulation near the exit. The high patch conductivity and the concentration profiles lead to local electric field perturba- tions that may facilitate preconcentration. This study includes analytical expressions of ion concentrations and electrochemical potentials at small to moderate electric fields, as well as numerical simulations. Additionally, a simple matrix of poly- nomial coefficients (obtained via fitting of numerical data) enables analytical calculation of the two-dimensional concen- tration profiles at all electric fields within the range investigated in the numerical simulations. This is possible because a single dimensionless parameter controls this problem.Postprint (updated version

Secondary opening of productive layers by mechanical devices

When using mechanical perforators, the destruction of the cement ring is excluded and, accordingly, the tightness of the sealed space is preserved, rock compaction and contamination of the walls of the perforation channels with explosion products is excluded. The productivity of the well increases, up to a multiple, and the ecological cleanliness of the perforation process is ensured. The most preferred use of mechanical perforation in the development of low-power oil-saturated intervals, which for one reason or another were not used at the initial stage of field exploitation

ElectroOsmoDialysis

Concentration Polarization (CP) and limiting-current phenomena are well-known to limit the productivity of electrodialysis by reducing the current efficiency at higher current densities. Considerable effort has been devoted to attempts to reduce the CP primarily via intensification of external mass transfer close to the membrane surfaces. However, it is notoriously difficult to stir liquids very close to solid surfaces so intensification of cross-flow hydrodynamics has only limited impact and obviously implies additional energy costs. In conventional electro-membrane systems, limiting-current phenomena occur because salt is delivered to polarized membrane/solution interfaces primarily by diffusion. Its rate is limited since the salt concentration cannot drop below zero. In liquids convection is a much more effective transport mechanism than diffusion. Therefore, much attention has been paid to the so-called electro-convection in electro-membrane processes. Nonetheless at short distances from the membrane surfaces even electro-convection remains predominantly tangential so its rate is limited due to the no-slip condition. Normal convection would be much more effective but in the case of conventional ion-exchange membranes it is very week owing to the extremely low mechanical permeability of these membranes. At the same time, with nano-porous charged diaphragms the limiting current can be effectively suppressed due to the normal electro-osmotic flow [1]. This presentation will show in what way considerable (quasi)normal convective flow through ion-exchange membranes (IEXMs) can be arranged for. This can be achieved via creating relatively scarce microscopic perforations in the otherwise almost impermeable membrane matrix. The transmembrane volume flow can be created in several ways but in this presentation we will consider the scenario of putting a nano-porous layer in series with the perforated IEXM so that the former works as an electroosmotic pump. In this case the liquid flow through the perforated IEXM is predominantly driven by the electroosmotic pressure gradients arising within the nanoporous electroosmotic layer. Via numerical simulations, we will demonstrate that due to this (quasi)normal convection (and corresponding salt delivery to the current-polarized interface), limiting current, indeed, is suppressed. Nonetheless, the CP phenomenon itself does not disappear. With increasing current density the salt concentration tends not to zero but to a finite limiting value, which is a function of system parameters. Evidently, in addition to the decrease in the concentration (similar to the conventional ED) there is a volume transfer across the “sandwich”. If a cell pair is formed by two perforated IEXMs of opposite polarity (each “sandwiched” with its own nanoporous EO layer of opposite surface charge) the volume flows through the composite membranes have opposite directions and can merge into a tangential flow along a channel separating them. Due to this, one can expect increased product recovery as compared to the conventional ED. In view of the important role played by electroosmosis, this novel membrane separation process can be termed ElectroOsmoDialysis (EOD). [1] A. Yaroshchuk, What makes a nano-channel? A limiting-current criterion, Microfluid. Nanofluidics. 12 (2012) 615–624. doi:10.1007/s10404-011-0902-6

Balance-of-force selective accumulation of trace ionic species in hierarchical sub-nano-/nano-/micro-porous structures

Separation of species of close electrochemical mobilities (peptides, isotopes) is of interest for a number of applications. In this presentation, we will explore selective accumulation of ionic species in current-polarized hierarchical sub-nano-/nano-/micro-porous structures. Please click Additional Files below to see the full abstract

Conceptual model for the development of geo-ecological atlas of the natural reserve fund of Ukraine

The article substantiates that the most complete cartographic model, which comprehensively characterizes the objects and territories of the natural reserve fund (NRF) of Ukraine is the geo-ecological atlas. It is indicated that the basis for the creation of the atlas is its conceptual model, within the framework of the formulation of its provisions are defined: the object of modeling, structure and composition of the modeled system, the characteristics of its elements, as well as inherent in the system cause-effect relationships that are considered essential to achieve the purpose of modeling. The functions of the atlas of NRF are formulated. The formal features of its content are interconnected. The authors in the context of the formulation and use of methodological principles of atlas completing with maps (sequential-traditional; block-issue; combined) applied combined principle and determined the optimal thematic content of the atlas in the form of a list of maps, grouped by sections and blocks (three sections, each of which contains two blocks of maps). The types of maps included in each section / block are defined (mainly they are: analytical (inventory), analytical-synthetic (evaluation), synthetic (recommendation, forecast), for each of which the indicators of mapping and methods of cartographic representation are justified

Кількісне визначення глутатіону за ефектом інгібування хемілюмінесценції в реакції каталітичного окиснення люмінолу гідроген пероксидом у присутності гемоглобіну

Aim. To develop a method for the quantitative determination of reduced glutathione in a lyophilized powder for the preparation of “Hepaval®” solution for intravenous and intramuscular administration by the effect of inhibiting chemiluminescence in the luminol (H2L)–Н2О2–hemoglobin (Hb) system.Materials and methods. The study object was the reduced glutathione substance and lyophilized powder for the preparation of “Hepaval®” solution for injection, ampoules of 4 mL No. 10 manufactured by “Valartin pharma” (Italy). The glutathione content in powder was determined using the chemiluminescence method by the effect of inhibiting the luminol oxidation reaction with hydrogen peroxide in the presence of Hb as a catalyst. The analysis was performed by the standard addition method.Results and discussion. As a result of the studies, it has been found that under optimal conditions glutathione shows a noticeable inhibitory effect on chemiluminescence in the H2L–H2O2–Hb system. This phenomenon was used to develop a new procedure for the quantitative determination of glutathione in the substance and lyophilized powder for the preparation of “Hepaval®” aqueous solution for injection. The linear dependence of the integral chemiluminescence intencity (S) on the molar concentration of glutathione was maintained in the concentration range of (2 – 20) × 10–7 mol L-1. The graph equation was S = (–1.6 ± 0.2) × 107 × c + (198.9 ± 2.0), (r = 0.999). The relative standard deviation (RSD) was ±1.82 % (n = 7, P = 0.95). Conclusions. The method has been developed, and the possibility of the quantitative determination of glutathione in powder for the preparation of “Hepaval®” solution for injection by the method of the chemiluminescence inhibition of the H2L–Н2О2–Нb system has been shown. The content of glutathione in powder calculated with reference to dried substance was 91.49 % (against 90.8 % by the certificate). The accuracy was +0.76 %.Мета. Розробити методику кількісного визначення відновленого глутатіону в ліофілізованому порошку для приготування розчину для внутрішньовенного та внутрішньом’язового введення «Гепавал®» за ефектом інгібування хемілюмінесценції системи люмінол (H2L)–Н2О2–гемоглобін (Hb).Матеріали та методи. Об’єктом дослідження були відновлений глутатіон та ліофілізований порошок для приготування розчину для ін’єкцій «Гепавал®», ампули по 4 мл № 10 виробництва «Валартин фарма» (Італія). Визначення вмісту глутатіону в порошку здійснювали методом хемілюмінесценції за ефектом інгібування реакції окиснення люмінолу гідроген пероксидом у присутності Hb як каталізатора процесу. Аналіз проводили методом стандартних добавок.Результати та їх обговорення. У результаті дослідження з’ясовано, що в оптимальних умовах глутатіон виявляє помітну інгібувальну дію на хемілюмінесценцію в системі H2L–H2O2–Hb. Це явище було використано для опрацювання нової методики кількісного визначення глутатіону в субстанції та ліофілізованому порошку для приготування водного розчину для ін’єкцій «Гепавал®». Лінійна залежність сумарного світіння (S) від молярної концентрації глутатіону зберігалася в інтервалі концентрацій (2 – 20) × 10–7 моль л–1. Рівняння графіка має вигляд S = (–1,6 ± 0,2) × 107c + (198,9 ± 2,0), (r = 0,999). Відносне стандартне відхилення (RSD) становило ±1,82 % (n = 7, P = 0,95).Висновки. Розроблено методику та продемонстровано можливість кількісного визначення глутатіону в порошку для приготування розчину для ін’єкцій «Гепавал®» методом інгібування хемілюмінесценції системи H2L – Н2О2 – Нb. Вміст глутатіону в порошку в перерахунку на суху речовину становив 91,49 % (проти 90,8 % за сертифікатом). Правильність становила +0,76 %

Problem aspects of interaction of law enforcement authorities in the field of countering money laundering

One of the biggest obstacles to maintaining an effective international financial system is money laundering. Money laundering is also extremely difficult to investigate and prosecute. The latter task is entrusted to law enforcement agencies. The purpose of the article is to characterize the problematic aspects of law enforcement cooperation in the field of combating money laundering in Ukraine and finding optimal ways to solve them. During the study, the authors used the following methods: dialectal, terminological analysis and operationalization of concepts, analysis and refinement, analysis, and synthesis, sociological and statistical. The article emphasizes that the normative sources of ways of interaction between law enforcement agencies in the field of combating money laundering are set out in a rather fragmentary manner, without any specifics regarding the specific boundaries, scope of cooperation. This situation inevitably leads to various kinds of abuse and conflict. In our opinion, given the importance of the task of combating money laundering, the main task is to clearly regulate the ways and methods of cooperation between law enforcement agencies in this area and the introduction of administrative liability for failure to take measures or evasion of such cooperation

The essence and methods of calling the influx of fluids from wells

A well development is a set of works that is carried out after the completion of drilling a well in order to obtain gas inflow from the reservoir and further study it. The development of reservoirs must be carried out in the presence of an act on the readiness of the well to perform these works. For each prospecting or exploration well, a development plan is drawn up, which is approved by the head of the geological services of a higher organization

Information and Communication Technologies as a Means of Formation of Professional Competence of Future Teachers of Building Profile

У статті розкрито значення інформаційно-комунікаційних технологій у формуванні професійної компетентності майбутніх педагогів будівельного профілю.The article reveals the importance of information and communication technologies in shaping the professional competence of future educators of the construction profile

Extending service life of rails in the case of a rail head defect

Tračnice su tijekom svoje uporabe izložene procesima trošenja, korozije i kontaktnog zamora uslijed savijanja. Kao posljedica tih procesa, na tračnicama dolazi do raznih oštećenja i neispravnosti. Nastavak uporabljivosti tračnica ovisi o veličini, položaju i smjeru oštećenja. U ovom su radu izračunane maksimalno dopuštene vrijednosti veličine pukotine metodom konačnih elemenata. Smjer ravnine pukotine analiziran je u odnosu na ravninu kontaktne površine kotač-tračnica. Utemeljena je ovisnost faktora veličine naprezanja o površini pukotine. To omogućuje daljnju upotrebu oštećenih tračnica i siguran nastavak rada na željezničkim prugama sa slabijom aktivnošću.Rails are subjected to the processes of wear, corrosion and contact and bending fatigue during their lifecycle. As a result of these processes, various types of damage and defects are formed in rails. The residual life of rails depends on the size, position, and orientation of defects. Maximum permissible crack-size values are calculated in this paper using the finite element method. The crack plane orientation relative to the contact surface plane is analysed. The dependence of the stress intensity factor on the crack area is established. This allows continued use of defective rails and safe operation on low-activity railways