Hydrogen desorption from alloys Mg–Cu(–KCl): Cu catalysis in detail

Effect of chemical composition of Mg-xCu based alloys (x = 9.94–58.00 wt %) modified by KCl upon their hydrogen storage performance was studied. Kinetic curves and pressure-concentration isotherms were measured in the ranges up to 60 bar and 388 °C, respectively. It was observed that desorption rate dc/dt is not significantly influenced by the composition. Unknown Cu-rich phase was detected that has shown a catalytic effect on desorption from a mixture with other phases. Activation energy of hydrogen desorption decreased with increasing x from 180 kJ/mol down to 98 kJ/mol. Average hydride dissociation enthalpy, ΔH, for the lowest plateau was 75 kJ/mol which is equal to literature value for pure Mg. Slightly lover average value, 67 kJ/mol was obtained for the second plateau and ΔH for the third one decreased from 70 kJ/mol for the lowest to 49 kJ/mol for the highest x.     

Mycotoxin exposure and human cancer risk: A systematic review of epidemiological studies

In recent years, there has been an increasing interest in investigating the carcinogenicity of mycotoxins in humans. This systematic review aims to provide an overview of data linking exposure to different mycotoxins with human cancer risk. Publications (2019 and earlier) of case–control or longitudinal cohort studies were identified in PubMed and EMBASE. These articles were then screened by independent reviewers and their quality was assessed according to the Newcastle–Ottawa scale. Animal, cross‐sectional, and molecular studies satisfied criteria for exclusion. In total, 14 articles were included: 13 case–control studies and 1 longitudinal cohort study. Included articles focused on associations of mycotoxin exposure with primary liver, breast, and cervical cancer. Overall, a positive association between the consumption of aflatoxin‐contaminated foods and primary liver cancer risk was verified. Two case–control studies in Africa investigated the relationship between zearalenone and its metabolites and breast cancer risk, though conflicting results were reported. Two case–control studies investigated the association between hepatocellular carcinoma and fumonisin B1 exposure, but no significant associations were observed. This systematic review incorporates several clear observations of dose‐dependent associations between aflatoxins and liver cancer risk, in keeping with IARC Monograph conclusions. Only few human epidemiological studies investigated the associations between mycotoxin exposures and cancer risk. To close this gap, more in‐depth research is needed to unravel evidence for other common mycotoxins, such as deoxynivalenol and ochratoxin A. The link between mycotoxin exposures and cancer risk has mainly been established in experimental studies, and needs to be confirmed in human epidemiological studies to support the evidence‐based public health strategies.     

Ordinary Gasoline Emissions Induce a Toxic Response in Bronchial Cells Grown at Air-Liquid Interface

Gasoline engine emissions have been classified as possibly carcinogenic to humans and represent a significant health risk. In this study, we used MucilAir™, a three-dimensional (3D) model of the human airway, and BEAS-2B, cells originating from the human bronchial epithelium, grown at the air-liquid interface to assess the toxicity of ordinary gasoline exhaust produced by a direct injection spark ignition engine. The transepithelial electrical resistance (TEER), production of mucin, and lactate dehydrogenase (LDH) and adenylate kinase (AK) activities were analyzed after one day and five days of exposure. The induction of double-stranded DNA breaks was measured by the detection of histone H2AX phosphorylation. Next-generation sequencing was used to analyze the modulation of expression of the relevant 370 genes. The exposure to gasoline emissions affected the integrity, as well as LDH and AK leakage in the 3D model, particularly after longer exposure periods. Mucin production was mostly decreased with the exception of longer BEAS-2B treatment, for which a significant increase was detected. DNA damage was detected after five days of exposure in the 3D model, but not in BEAS-2B cells. The expression of CYP1A1 and GSTA3 was modulated in MucilAir™ tissues after 5 days of treatment. In BEAS-2B cells, the expression of 39 mRNAs was affected after short exposure, most of them were upregulated. The five days of exposure modulated the expression of 11 genes in this cell line. In conclusion, the ordinary gasoline emissions induced a toxic response in MucilAir™. In BEAS-2B cells, the biological response was less pronounced, mostly limited to gene expression changes.     

Ultrathin hydroxyapatite coating on pure magnesium substrate prepared by pulsed electron ablation technique

Magnesium (Mg) as a potential material for biodegradable implants is attractive due to its mechanical similarity to the bone tissue and nontoxic corrosion products. However, the rapid corrosion rate of bare magnesium is associated with hydrogen release, which may complicate the healing process. The corrosion rate may be reduced by suitable alloying, but concurrently the biocompatibility of such alloy might be deteriorated. Another way of reduction of the corrosion rate is coating. Hydroxyapatite (HA)-based coating is considered to improve biocompatibility as well as decrease the corrosion rate by the barrier effect. In this study, ultrathin (150 nm) HA and HA containing Sr coatings are deposited via pulsed electron ablation technique on pure Mg. The microstructure of the coating was assessed by scanning electron microscopy. Electrochemical methods were used to investigate the corrosion properties of prepared coatings. The materials covered by this layer were characterized by superior corrosion behavior, with corrosion rates of coated samples up to five times lower as compared with the uncoated ones. Such coating is the thinnest coating found in the literature sources.     

Fluorine containing self‐crosslinking acrylic latexes with reduced flammability and their application as polymer binders for heterogeneous cation‐exchange membranes

In this study, self‐crosslinking core–shell latexes comprising copolymerized perfluorethyl groups and a novel flame retardant based on phosphazene derivative were prepared by the semi‐continuous non‐seeded emulsion polymerization of 2,2,2‐trifluorethyl methacrylate, methyl methacrylate, butyl acrylate, methacrylic acid, and hexaallylamino‐cyclo‐triphosphazene as main monomers. For interfacial crosslinking, diacetone acrylamide was copolymerized into the shell layer of latex particles to provide sites for subsequent reaction with adipic acid dihydrazide. The heterogeneous cation‐exchange membranes were obtained by dispersing commercial strong acid cation‐exchange resin powder in the latex binder and casting the mixture followed by keto‐hydrazide crosslinking reaction. It was found that the increased concentration of fluorine atoms and phosphazene units in the macromolecular structure of interfacially crosslinked emulsion polymers resulted in a significant enhancement of their flame resistance and shape stability in aqueous environment. Moreover, the easily prepared heterogeneous cation‐exchange membranes based on latexes with higher amounts of fluorine and phosphazene units were shown to exhibit satisfactory physicochemical and electrochemical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45467.     

Prediction of Speech Quality Based on Resilient Backpropagation Artificial Neural Network

The paper presents a system for monitoring and assessment the speech quality in the IP telephony infrastructures using modular probes. The probes are placed at key nodes in the network where aggregating packet loss data. The system dynamically measures speech quality and results are collected on a central server. For data analysis we applied four-state Markov model for modeling the impact of network impairments on speech quality, afterwards, the resilient back propagation (Rprop) algorithm was used to train a neural network. Information about the speech quality are displayed in the form of automatically generated graphs and tables. The proposed solution has been tested with selected codecs and further generalizes the already presented concepts of the speech quality estimation in the IP environment.

     

Failure Resistance of the Historic Stone Bridge Structure of Charles Bridge. I: Susceptibility to Nonstress Effects

The monitoring of deformations of the stone structure of Charles Bridge in Prague proved the gravity and relevance of nonstress effects (temperature, moisture content) on cyclic deformations and permanent strain accompanied by a gradual disintegration of its stone masonry, growing tilt of the breast walls, and development of cracks in the masonry of the stone bridge structure. Each deformation cycle is accompanied by a gradual growth in permanent deformations. The “unmanifested” primary deformation due to, e.g., a temperature change causes a mechanical state of tension, and it is mainly the tensile stresses thus arising that contribute to the development of tensile cracks in the stone masonry.     

Problem of the reference height of the projectile trajectory as a reduced meteo-ballistic weighting factor

This paper deals with the issue of preparation of the aiming angles with the use of tabular firing tables and needed determination of the ballistic elements μB （ballistic wind wB Wxm WzB, ballistic （virtual） temperature τB, ballistic density ρB） from the standardized met messages. The weighting factors are used for the calculation of ballistic elementsμB that are incorporated into the trajectory calculations characteristics of weapon and ammunition. Two different methodologies practically used in the praxis are analysed and compared. For the comparison of the two methodologies the reference height of trajectory determined from the weighting factor functions is employed. On the basis of the analyses conducted, the potential for further increase in accuracy of these aiming angles preparation methods is pointed out.     

Untersuchung der thermisch‐hygrischen Eigenschaften von Ziegeln mit Hohlraumfüllung aus Recyclingmaterial

Investigation on the thermal‐hygral behaniour of bricks with canity filling by recycling meterials. In the investigation project was examined whether bricks with simple cavity structure have a higher heat resistance by use of a heat insulation material filling in the cavities. The insulation material is a recycled product made of polystyrene and wood covered and bonded with cement. The influence of the configuration and thickness of the perforated bricks with vertical perforations and the geometry of the cavities of the brick on the thermal moisture states was evaluated. For investigation of the thermal resistance and the heat transmission coefficients were used the simulation program THERM, that considered the heat transportation through conduction in the brick fragments and the transport mechanisms conduction, convection and radiation in the airfilled cavities. The software package WUFI 2D was employed for the investigation of moisture transfer in the bricks. The investigations showed that the composite brick insulation stone has a thermal resistance twice as high as the initial brick. The moisture states can be partially in the brick more than 80 % humidity. This load is estimated as uncritical because the wooden particles are covered with cement slime.