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Electrochemistry from first-principles in the grand canonical ensemble
- Arihant Bhandari
- Chao Peng
- Jacek Dziedzic
- Lucian Anton
- John R. Owen
- Denis Kramer
- Chris-Kriton Skylaris
2021 Pełny tekst JOURNAL OF CHEMICAL PHYSICS
Progress in electrochemical technologies, such as automotive batteries, supercapacitors, and fuel cells, depends greatly on developing improved charged interfaces between electrodes and electrolytes. The rational development of such interfaces can benefit from the atomistic understanding of the materials involved by first-principles quantum mechanical simulations with Density Functional Theory (DFT). However, such simulations are typically performed on the electrode surface in the absence of its electrolyte environment and at constant charge. We have developed a new hybrid computational method combining DFT and the Poisson–Boltzmann equation (P–BE) capable of simulating experimental electrochemistry under potential control in the presence of a solvent and an electrolyte. The charged electrode is represented quantum-mechanically via linear-scaling DFT, which can model nanoscale systems with thousands of atoms and is neutralized by a counter electrolyte charge via the solution of a modified P–BE. Our approach works with the total free energy of the combined multiscale system in a grand canonical ensemble of electrons subject to a constant electrochemical potential. It is calibrated with respect to the reduction potential of common reference electrodes, such as the standard hydrogen electrode and the Li metal electrode, which is used as a reference electrode in Li-ion batteries. Our new method can be used to predict electrochemical properties under constant potential, and we demonstrate this in exemplar simulations of the differential capacitance of few-layer graphene electrodes and the charging of a graphene electrode coupled to a Li metal electrode at different voltages
Electromagnetic Field Associated With Dermoscope Magnets May Affect the Safety of Cardiac Implanted Electronic Devices Patients
- Grzegorz Sławiński
- Martyna Sławińska
- Zbigniew Usarek
- Michał Sobjanek
- Maciej Kempa
- Aleksandra Liżewska-Springer
- Ewa Lewicka
- Roman Janusz Nowicki
- Grzegorz Raczak
2021 Pełny tekst Frontiers in Cardiovascular Medicine
Dermoscopy is currently used as an auxiliary tool in general dermatology. Since some commercially available dermoscopes have built-in magnets, electromagnetic interference (EMI) may occur when examining cardiac implantable electronic devices (CIED) patients. The aim of the study was to create maps of electromagnetic fields defining a safe distance in terms of EMI. The study was performed in laboratory conditions using measuring equipment specially designed for this purpose. The following dermoscopes have been tested: Illuco IDS-1100, Visiomed Luminis, Visiomed Luminis 2, Heine NC2 with and without a contact plate, DermLite DL4, and DermLite Handyscope. Measurements were made for the following set of lift-off distances: 5, 10, 20, 30, 40, 50, and 150 mm. Each 2D scan consisted of 10-line scans shifted from each other by 10 mm. The strength of the magnetic field decreased with the distance from the faceplate. The distribution of the magnetic field differed depending on the position of the magnets. The highest magnetic field was recorded in the center of the Heine NC2 faceplate (up to 8 mT). In most cases, at a distance of 10 mm, the magnetic field strength was measured below 1 mT, with the exception of Heine NC2 and Heine NC2 with a contact plate. All tested dermoscopes generated a magnetic field of <1 mT at the distance of 20 mm. The use of dermoscopes with built-in magnets may affect the functioning of CIEDs, and the impact may vary depending on the type of dermoscope.
Electron attachment to representative cations composing ionic liquids
- Iwona Anusiewicz
- Sylwia Freza
- Maciej Bobrowski
- Piotr Skurski
2021 Pełny tekst JOURNAL OF CHEMICAL PHYSICS
Using ab initio electronic structure methods with flexible atomic orbital basis sets, we investigated the electronic structure and stability of reduction products of selected representative cations (C+) constituting ionic liquids. We found that an electron attachment to such cations leads to the neutral radicals, whereas a subsequent attachment of another (i.e., excess) electron leads to adiabatically stable anions only in two cases {[P(CH3)4]- and [MeMePyr]−}. The possibility of the formation of various dimers (such as CC+, CC, and CC-) was also considered, and the resulting systems were characterized by predicting their lowest energy structures, ionization potentials, electron affinities, and susceptibilities to the fragmentation process. Among the cations studied, only the [MeMePyr] + was found to form a typical Rydberg radical (MeMePyr) and double-Rydberg anion ([MeMePyr]-), whereas the remaining cations were predicted to form neutral rad- icals of a primarily valence (MeMeIm and MePy) or mixed Rydberg-valence [P(CH3)4] character. Our calculations confirmed the stability of all CC+ and CC dimers against fragmentation yielding the corresponding monomers (the binding energies of 12.2--20.5 kcal/mol and 11.3--72.3 kcal/mol were estimated for CC+ and CC dimers, respectively). [(MeMePyr)2]- was identified as the only adiabatically stable CC- dimeric anion having its vertical electron detachment energy of 0.417 eV. We also found that in the [(MeMePyr)2]- anionic state, three outermost electrons are described by Rydberg orbitals, which results in the (σ)2 (σ*)1 configuration.
Electron-Induced Decomposition of Uracil-5-yl O-(N,N-dimethylsulfamate): Role of Methylation in Molecular Stability
- Eugene Arthur-Baidoo
- Karina Falkiewicz
- Lidia Chomicz-Mańka
- Anna Czaja
- Sebastian Demkowicz
- Karol Biernacki
- Witold Kozak
- Janusz Rak
- Stephan Denifl
2021 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
The incorporation of modified uracil derivatives into DNA leads to the formation of radical species that induce DNA damage. Molecules of this class have been suggested as radiosensitizers and are still under investigation. In this study, we present the results of dissociative electron attachment to uracil-5-yl O-(N,N-dimethylsulfamate) in the gas phase. We observed the formation of 10 fragment anions in the studied range of electron energies from 0–12 eV. Most of the anions were predominantly formed at the electron energy of about 0 eV. The fragmentation paths were analogous to those observed in uracil-5-yl O-sulfamate, i.e., the methylation did not affect certain bond cleavages (O-C, S-O and S-N), although relative intensities differed. The experimental results are supported by quantum chemical calculations performed at the M06-2X/aug-cc-pVTZ level of theory. Furthermore, a resonance stabilization method was used to theoretically predict the resonance positions of the fragment anions O- and CH3-.
Electrophoretic Deposition of Chitosan/Eudragit E 100/AgNPs Coatings for Controlled Release of Antibacterial Substance
- Łukasz Pawłowski
- Andrzej Zieliński
2021
The development of bacterial infection of the tissues surrounding an implant is one of the leading causes of implant surgery failure. In order to prevent the deposition of bacteria on the implant surface and the formation of biofilm, coatings that exhibit antibacterial properties are manufactured. However, the problem is the controlled release of the therapeutic substance from the coating over the extended life of the implant [1], [2]. Usually, the active substance is released immediately when the implant is inserted into an environment simulating human body fluids, which results in burst release phenomenon, namely, the release of a large dose of active substance in a short period of time, which may result in a toxic effect. Unfortunately, chitosan, one of the most commonly used biopolymers in controlled drug delivery systems, is unstable in neutral pH environments, readily absorbs water, and swells, resulting in rapid release of the therapeutic agent. Therefore, it is necessary to limit the dissolution rate of the chitosan coating at neutral pH. Previous studies [3] have confirmed that the addition of Eudragit E 100, a cationic copolymer based on dimethylaminoethyl methacrylate, butyl methacrylate, and methyl methacrylate in a 2:1:1 ratio, to chitosan coatings significantly reduced the degradation of these coatings in artificial saliva solution at neutral pH while maintaining high sensitivity to pH drop. Hence, a biopolymer matrix of this type should provide a good carrier for an active substance, such as metallic nanoparticles with antibacterial activity, which will be released only when inflammation of peri-implant tissues occurs. The scientific objective of this study was to fabricate a smart composite coating of chitosan/Eudragit E 100/silver nanoparticles (chit/EE100/AgNPs) on grade 2 titanium surface using variable deposition parameters such as AgNPs concentration, voltage, and deposition time by the electrophoretic method. The determinant of the process of creating such composite coatings with EE100 by electrophoretic method on the surface of Ti grade 2 has not been determined yet. No publication concerning investigations of coatings containing chitosan/EE100 with silver nanoparticles has been found. The microstructure, surface roughness, thickness, chemical and phase composition, mechanical and electrochemical properties, silver release rate at different pH, and wettability of the produced coatings were investigated...
Electrophoretically Deposited Chitosan/Eudragit E 100/AgNPs Composite Coatings on Titanium Substrate as a Silver Release System
- Łukasz Pawłowski
- Michał Bartmański
- Aleksandra Mielewczyk-Gryń
- Bartłomiej Cieślik
- Grzegorz Gajowiec
- Andrzej Zieliński
2021 Pełny tekst Materials
Due to the possibility of bacterial infections occurring around peri-implant tissues, it is necessary to provide implant coatings that release antibacterial substances. The scientific goal of this paper was to produce by electrophoretic deposition (EPD) a smart, chitosan/Eudragit E 100/silver nanoparticles (chit/EE100/AgNPs) composite coating on the surface of titanium grade 2 using different deposition parameters, such as the content of AgNPs, applied voltage, and time of deposition. The morphology, surface roughness, thickness, chemical and phase composition, wettability, mechanical properties, electrochemical properties, and silver release rate at different pH were investigated. Using lower values of deposition parameters, coatings with more homogeneous morphology were obtained. The prepared coatings were sensitive to the reduced pH environment.
Electrostatic Zipping Actuators—Analysis of the Pull-In Effect Depending on the Geometry Parameters
- Jacek Szkopek
- Grzegorz Redlarski
- Arkadiusz Żak
2021 Pełny tekst ENERGIES
Continuous work on a new generation of actuators, referred to as artificial muscles, resulted in the initiation of work on electrostatic zipping actuators, the concept of which is derived from micro electro-mechanical devices. Despite partial knowledge of their basic operating parameters, a question remains whether electrostatic zipping actuators are able to meet the expectations in the context of generated forces and control possibilities. In order to get closer to the answer to this question, the authors of this work created a solution method using FEM, which allowed them to conduct a series of concentric contraction tests of the desired solution. In addition to the basic features of the actuators tested, such as their length, thickness and width, for the first time the size of the weld surface, to which the loading force was applied, was taken into account. The results of the investigations show the possibility of adjusting the supply voltage range to the application requirements, but most importantly, they present the variability of the pull-in strain parameter. In extreme configurations, its value increases from ~10% to ~26%. The results obtained emphasize the need for further analysis of electrostatic zipping actuators using FEM. It will make it possible to precisely define the characteristics of this technology as well as its limits. These activities will provide the ultimate answer to the potential of electrostatic zipping actuators as artificial muscles.
Elemental and water-insoluble organic carbon in Svalbard snow: a synthesis of observations during 2007–2018
- Christian Zdanowicz
- Jean-Charles Gallet
- Mats P. Björkman
- Catherine Larose
- Thomas Schuler
- Bartłomiej Luks
- Krystyna Koziol
- Andrea Spolaor
- Elena Barbaro
- Tõnu Martma
- Ward van Pelt
- Ulla Wideqvist
- Johan Ström
2021 Pełny tekst ATMOSPHERIC CHEMISTRY AND PHYSICS
Light-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplifying Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their distribution in snow is needed to assess their impact. Here we present and synthesize new data obtained on Svalbard between 2007 and 2018, comprising measurements of elemental (EC) and water-insoluble organic carbon (WIOC) in snow from 37 separate sites. We used these data, combined with meteorological data and snowpack modeling, to investigate the variability of EC and WIOC deposition in Svalbard snow across latitude, longitude, elevation and time. Overall, EC concentrations (CECsnow) ranged from <1.0 to 266.6 ng g−1, while WIOC concentrations (CWIOCsnow) ranged from <1 to 9426 ng g−1, with the highest values observed near Ny-Ålesund. Calculated snowpack loadings (LECsnow, LWIOCsnow) on glaciers surveyed in spring 2016 were 0.1 to 2.6 mg m−2 and 2 to 173 mg m−2, respectively. The median CECsnow and the LECsnow on those glaciers were close to or lower than those found in earlier (2007–2009), comparable surveys. Both LECsnow and LWIOCsnow increased with elevation and snow accumulation, with dry deposition likely playing a minor role. Estimated area-averaged snowpack loads across Svalbard were 1.1 mg EC m−2 and 38.3 mg WIOC m−2 for the 2015–2016 winter. An ∼11-year long dataset of spring surface snow measurements from the central Brøgger Peninsula was used to quantify the interannual variability of EC and WIOC deposition in snow. In most years, CECsnow and CWIOCsnow at Ny-Ålesund (50 m a.s.l.) were 2–5 times higher than on the nearby Austre Brøggerbreen glacier (456 m a.s.l.), and the median EC/WIOC in Ny-Ålesund was 6 times higher, suggesting a possible influence of local EC emission from Ny-Ålesund. While no long-term trends between 2011 and 2018 were found, CECsnow and CWIOCsnow showed synchronous variations at Ny-Ålesund and Austre Brøggerbreen. When compared with data from other circum-Arctic sites obtained by comparable methods, the median CECsnow on Svalbard falls between that found in central Greenland (lowest) and those in continental sectors of European Arctic (northern Scandinavia, Russia and Siberia; highest), which is consistent with large-scale patterns of BC in snow reported by surveys based on other methods.
Elemental composition, environment of deposition of the Lower Carboniferous Emma Fiord Formation oil shale in Arctic Canada
- Fariborz Goodarzi
- Nina Goodarzi
- Aleksandra Małachowska
2021 INTERNATIONAL JOURNAL OF COAL GEOLOGY
The sedimentary succession of 51-m consisting of a thin coal seam (1 m) and oil shale with a marlstone and carbonate-mudstone matrix of the Lower Carboniferous (Viséan) Emma Fiord Formation located on the Grinnell Peninsula, Devon Island, Arctic Canada was examined. The techniques used include reflected light microscopy, and instrumental neutron activation analysis (INAA) for elemental concentration, and inductively coupled plasma emission spectrometry (ICPES) for boron concentration.The coal and oil shale was deposited in a lacustrine, freshwater environment. Due to the climatic variation, two types of oil shale were developed based on the amount of precipitation.One with carbonate-mudstone matrix, with high calcite (75%) and low TOC (1.14–1.87%) content, a marlstone-dominated matrix with high aluminosilicate (64%) and TOC (16.4–53.6%). Oil shale from Emma Fiord experienced a slow rate of sedimentation and terrestrial flux as determined using Th/K/ Na/K, ratios Mn/Ca ratio to Ca respectively, and compared to the oil shale of Carboniferous age deposited in a lacustrine environment with a regular rate of recharge/discharge.The redox conditions for the Emma Fiord oil shale indicate anoxic to dysoxic conditions based on the variation of Cr and Ni + V, as well as fluctuation of V/Cr ratio and Cr.Thorium and U systematics indicate that U is more concentrated in oil shale with marlstone matrix and is associated with clay minerals and organic matter (OM), similar to the Carboniferous oil shale from the Big Marsh. The authigenic U is associated with TOC content and is higher for oil shale with the marlstone matrix.The variation of U with TOC and the hydrogen index (HI) indicates both paleo-productivity and preservation and is higher for oil shale with the marlstone matrix.The concentration of rare earth elements (REEs) is 95% due to the presence of light rare earth elements (LREEs) in both oil shale with marlstone and carbonate-mudstone matrices.The REES were normalized to the post-Archean average shale (PAAS). The high volatile bituminous coal at the base of the oil shale sections displays a flat, featureless pattern. The oil shale with a carbonate matrix decreases slightly from light rare earth elements (LREEs) to heavy rare earth elements (HREES).In contrast, the REEs concentration for oil shale with the marlstone matrix decreases more sharply from the LREEs (La-Eu) to HREEs (Tb-Lu). It displays a weak negative Eu anomaly typical of the upper continental crust.
Embedded gas sensing setup for air samples analysis
- Andrzej Kwiatkowski
- Katarzyna Drozdowska
- Janusz Smulko
2021 Pełny tekst REVIEW OF SCIENTIFIC INSTRUMENTS
This paper describes a measurement setup (eNose) designed to analyze air samples containing various volatile organic compounds (VOCs). The setup utilizes a set of resistive gas sensors of divergent gas selectivity and sensitivity. Some of the applied sensors are commercially available and were proposed recently to reduce their consumed energy. The sensors detect various VOCs at sensitivities determined by metal oxide sensors’ technology and operating conditions. The setup can utilize prototype gas sensors, made of resistive layers of different compositions, as well. Their properties can be modulated by selecting operating temperature or using UV light irradiation. The unit is controlled by an embedded system M5Stack Core2 ESP32 IoT. We used this development kit to program the measurement procedure and data recording fastly. The setup utilizes an aluminum gas chamber of a volume of 220 ml, a set of electrical valves to introduce there an air sample with the help of an electrical micropump. The handling of the setup was simplified to a selection of a few operations by touch screen only without a necessity of extra training. The recorded data are saved in a memory card for further processing. The evolved setup can be upgraded to apply more advanced data processing by utilizing WiFi or Bluetooth connection. The control program was prepared using the Arduino IDE software environment and can be further advanced with ease. The applied materials and the established measurement procedure can use various air samples, including exhaled breath samples for patients’ screening check-ups. We applied the same time of 10 min for response and recovery, acceptable for practical use.
Embedded Representations of Wikipedia Categories
- Jan Majkutewicz
- Julian Szymański
- Andrzej Sobecki
- Higinio Mora
- David Gil
2021
In this paper, we present an approach to building neural representations of the Wikipedia category graph. We test four different methods and examine the neural embeddings in terms of preservation of graphs edges, neighborhood coverage in representation space, and their influence on the results of a task predicting parent of two categories. The main contribution of this paper is application of neural representations for improving the structure of Wikipedia categories graph. We also show that a neural representation based solely on categories’ names can be an alternative to the other representations build using more complex approaches.
EM-Driven Multi-Objective Optimization of a Generic Monopole Antenna by Means of a Nested Trust-Region Algorithm
- Adrian Bekasiewicz
- Sławomir Kozieł
- Piotr Płotka
- Krzysztof Zwolski
2021 Pełny tekst Applied Sciences-Basel
Antenna structures for modern applications are characterized by complex and unintuitive topologies that are difficult to develop when conventional experience-driven techniques are of use. In this work, a method for automatic generation of antenna geometries in a multi-objective setup has been proposed. The approach involves optimization of a generic spline-based radiator with adjustable number of parameters using a nested trust-region-based algorithm. The latter iter-atively increases dimensionality of the radiator in order to gradually improve its performance. The method has been used to generate a set of nine antenna designs representing a trade-off between minimization of reflection within 3.1 GHz to 10.6 GHz and reduction of size. The properties of optimized designs vary along the Pareto set from –10 dB to –20 dB, and from 230 mm2 to 757 mm2 for the first, and the second objective, respectively. The presented design approach has been validated against a genuine population-based optimization routine. Furthermore, the smallest Pareto-optimal design has been compared to the antennas from the literature.
Emerging oxidized and defective phases in low-dimensional CrCl3
- Dario Mastrippolito
- Luca Ottaviano
- Jingsong Wang
- Jinjin Yang
- Faming Gao
- Mushtaq Ali
- Gianluca D'Olimpio
- Antonio Politano
- Stefano Palleschi
- Shafaq Kazim
- Roberto Gunnella
- Andrea DiCicco
- Anna Sgarlata
- Judyta Strychalska-Nowak
- Tomasz Klimczuk
- Robert J. Cava
- Luca Lozzi
- Gianni Profeta
2021 Pełny tekst Nanoscale Advances
Two-dimensional (2D) magnets such as chromium trihalides CrX3 (X ¼ I, Br, Cl) represent a frontier for spintronics applications and, in particular, CrCl3 has attracted research interest due its relative stability under ambient conditions without rapid degradation, as opposed to CrI3. Herein, mechanically exfoliated CrCl3 flakes are characterized at the atomic scale and the electronic structures of pristine, oxidized, and defective monolayer CrCl3 phases are investigated employing density functional theory (DFT) calculations, scanning tunneling spectroscopy (STS), core level X-ray photoemission spectroscopy (XPS), and valence band XPS and ultraviolet photoemission spectroscopy (UPS). As revealed by atomically resolved transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis, the CrCl3 flakes show spontaneous surface oxidation upon air exposure with an extrinsic long-range ordered oxidized O–CrCl3 structure and amorphous chromium oxide formation on the edges of the flakes. XPS proves that CrCl3 is thermally stable up to 200 C having intrinsically Cl vacancy-defects whose concentration is tunable via thermal annealing up to 400 C. DFT calculations, supported by experimental valence band analysis, indicate that pure monolayer (ML) CrCl3 is an insulator with a band gap of 2.6 eV, while the electronic structures of oxidized and Cl defective phases of ML CrCl3, extrinsically emerging in exfoliated CrCl3 flakes, show in-gap spin-polarized states and relevant modifications of the electronic band structures.
Emerging strategies for enhancing detection of explosives by artificial olfaction
- Wasilewski Tomasz
- Jacek Gębicki
2021 MICROCHEMICAL JOURNAL
Explosives detection systems need to be able to reliably detect a wide range of explosive materials and their vapours. The continued development and improvement of artificial olfaction techniques, including electronic nose (EN), remains important to overcome existing challenges and meet requirements posed by new improvements in the field of explosives. There is an increasingly popular trend aimed at improvement of fundamental metrological parameters of sensors for the construction of sensor arrays for the detection of ultralow target analytes. Even after decades of developments, applications of artificial olfaction instruments aimed at selective and sensitive detection of trace quantities of explosives constitute still a difficult and challenging problem. Essential aspects of artificial olfaction were theoretically discussed with an emphasis on evaluation of enhancing sensors parameters in the detection of explosives. Progress in nanotechnology and prospects in mimicking biological sense of smell successively remove the boundaries of artificial olfaction technologies. A tendency towards improved selectivity and specificity of the sensors is evident. Elaboration of novel sensing materials, data processing systems and sampling procedures are the main approaches to increase sensors’ major metrological parameters. Implementation of designed construction solutions in practice and meeting particular requirements are still a bottleneck in the commercialization process. The demonstration of achievements in artificial olfaction technology during the last couple of years is reviewed and different strategies to enhance their properties are suggested. Moreover, recent technological advancement including bio-inspired strategies, robots, drones and smartphones were described. Finally, we discuss emerging approaches to solve problems accompanied with direct and discriminative detection of explosives and outline future perspectives related to this topic.
EMI attenuation in a DC-DC buck converter using GaN HEMT
- Pawel B. Derkacz
- Piotr Musznicki
- Piotr Chrzan
2021 Pełny tekst IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
A dc-dc buck converter using gallium nitride (GaN) high electron mobility transistors (HEMT) is experimentally investigated at the discontinuous current mode (DCM) and at the triangular current mode (TCM) operation. The paper objective is to specify the power conversion efficiency and attenuation of common mode (CM) and differential mode (DM) noise voltage, measured at the line impedance stabilization network (LISN) for compared control strategies. Zero voltage switching achieved for the TCM operation improves efficiency with reference to the DCM operation. However, significant attenuation of electromagnetic interference (EMI) spectra is obtained for TCM operation with capacitive snubber. Sizing of capacitor snubber dependent on parasitic inductances of commutation circuit and rapid switching of GaN HEMTs are illustrated.
Emissions and toxic units of solvent, monomer and additive residues released to gaseous phase from latex balloons
- Mariusz Marć
- Stefan Tsakovski
- Marek Tobiszewski
2021 Pełny tekst ENVIRONMENTAL RESEARCH
This study describes the VOCs emissions from commercially available latex balloons. Nine compounds are determined to be emitted from 13 types of balloons of different colors and imprints in 30 and 60°C. The average values of total volatile organic compounds (TVOCs) emitted from studied samples ranged from 0.054 up to 7.18 μg∙g-1 and from 0.27 up to 36.13 μg∙g-1 for 30oC and 60oC, respectively. The dataset is treated with principal component analysis (PCA) and multiple curve resolution (MCR) to characterize its internal patterns. Here two groups on compounds are recognized – the first one related to balloon material, the second one being emissions of compounds previously adsorbed on balloon material. The toxicity assessment of MCR modeled balloons’ emissions was performed by toxic unit (TU) approach. The obtained TUs were summed to give toxicity emission assessment. The incorporation of TUs allows to identify the balloons with the most toxic emissions– imprinted ones in 60°C. The compounds of the highest TUs are hexanal and benzene. FTIR analysis shows that all balloons are made of the same polymeric material – isoprene, so all differences in emissions are related to different additives like pigments, imprints or these responsible for opaqueness. Analyzing the obtained research results it was noticed that latex balloons might be considered as an important source of emission of aliphatic and monoaromatic hydrocarbons to the gaseous phase.
Empirical analyses of robustness of the square Msplit estimation
- Zbigniew Wiśniewski
- Marek Zienkiewicz
2021 Journal of Applied Geodesy
The paper presents Msplit estimation as an alternative to methods in the class of robust M-estimation. The analysis conducted showed that Msplit estimation is highly efficient in the identification of observations encumbered by gross errors, especially those of small or moderate values. The classical methods of robust estimation provide then unsatisfactory results. Msplit estimation also shows high robustness to single gross errors of large values. The presented analysis of Msplit estimators’ robustness is of a chiefly empirical nature and is based on the example of a simulated levelling network and a real angular-linear network. Using the Monte Carlo method, mean success rates for outlier identification were determined and the courses of empirical influence functions were specified. The outcomes of the analysis were compared with the relevant values achieved via selected methods of robust M-estimation.
Employees With Autism Spectrum Disorders in the Digitized Work Environment: Perspectives for the Future
- Michał Tomczak
2021 Pełny tekst Journal of Disability Policy Studies
The aim of this article is to examine the opportunities for employees with autism spectrum disorders (ASDs), arising from digital technology (DT) development. The author discusses assistive technology (AT) as a mean of creating a better work environment, making the digitized workplace more friendly for people with ASD. A possible solution of communication problems is replacing the interpersonal communication between employees with electronic (non-direct) forms of communication, such as online communicators or chatbots. Another solution is the implementation of wearable electronic systems, monitoring stress levels and facilitating effective stress control. In the future, the whole digitized workplace could be designed according to a “smart workplace” concept. Sensors recording various human body parameters could be connected to a network with sensors recording physical parameters of the work environment (temperature, humidity,noise, smell, sunlight exposure) and also with controllers of its values, adjusting it dynamically to reduce distracting factors. As a result, communication, stress management, and sensory sensitiveness problems could be limited, improving the work comfort of people with ASD, and their colleagues. The pertinence of solutions proposed was also confirmed by the experts interviewed in the field who were asked to assess it in the context of future implementation.
Enabling simultaneous redox transformation of toxic chromium(VI) and arsenic(III) in aqueous media—A review
- Yu Fu
- Lingli Wang
- Wenya Peng
- Qingya Fan
- Qingchao Li
- Yongxia Dong
- Yunjiao Liu
- Grzegorz Boczkaj
- Zhaohui Wang
2021 JOURNAL OF HAZARDOUS MATERIALS
Simultaneous conversion of most harmful As(III) and Cr(VI) to their less toxic counterparts is environmentally desirable and cost-effective. It has been confirmed that simultaneous oxidation of As(III) to As(V) and reduction of Cr(VI) to Cr(III) can occur via free radical or mediated electron transfer processes. While Cr(VI) is reduced by reacting with H•, eaq−, photoelectron directly or undergoing ligand exchange with H2O2 and SO32−, As(III) is oxidized by HO•, SO4•−, O2•−, and holes (h+) in free radical process. The ability to concentrate Cr and As species on heterogeneous interface and conductivity determining the co-conversion efficiency in mediated electron transfer process. Acidity has positive effect on these co-conversion, while mediated electron transfer process is not much affected by dissolved oxygen (O2). Organic compounds (e.g., oxalate, citrate and phenol) commonly favor Cr(VI) reduction and inhibit As(III) oxidation. To better understand the trends in the existing data and to identify the knowledge gaps, this review elaborates the complicated mechanisms for co-conversion of As(III) and Cr(VI) by various methods. Some challenges and prospects in this active field are also briefly discussed.
Encapsulation of Amikacin into Microparticles Based on Low-Molecular-Weight Poly(lactic acid) and Poly(lactic acid-co-polyethylene glycol)
- Marta Glinka
- Katerina Filatova
- Justyna Kucińska-Lipka
- Eva Domincova Bergerova
- Andrzej Wasik
- Vladimir Sedlařík
2021 Pełny tekst MOLECULAR PHARMACEUTICS
The aim of this study was to fabricate novel microparticles (MPs) for efficient and long-term delivery of amikacin (AMI). The emulsification method proposed for encapsulating AMI employed low-molecular-weight poly(lactic acid) (PLA) and poly(lactic acid-co-polyethylene glycol) (PLA−PEG), both supplemented with poly(vinyl alcohol) (PVA). The diameters of the particles obtained were determined as less than 30 μm. Based on an in-vitro release study, it was proven that the MPs (both PLA/PVA- and PLA−PEG/PVA-based) demonstrated long-term AMI release (2 months), the kinetics of which adhered to the Korsmeyer−Peppasmodel. The loading efficiencies of AMI in the study were determined at the followings levels: 36.5±1.5 μg/mg for the PLA-based MPs and 106±32 μg/mg forthe PLA−PEG-based MPs. These values were relatively high and draw parallels with studies published on the encapsulation of aminoglycosides. The MPs provided antimicrobial action against the Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae bacterial strains. The materials were also comprehensively characterized by the following methods: differential scanning calorimetry; gel permeation chromatography; scanning electron microscopy; Fourier transform infrared spectroscopy−attenuated total reflectance; energy-dispersive X-rayfluorescence; and Brunauer−Emmett−Teller surface area analysis. The findings of this study contribute toward discerning new means for conducting targeted therapy with polar, broad spectrum antibiotics.