Determination of the Optimal Fourier Number on the Dynamic Thermal Transmission

This article represents the result of experimental research on transient heat transfer in a multilayered (heterogeneous) wall. Our non-steady thermal transmission simulation is based on a finite-difference calculation method. The value of a Fourier number shows the similarity of thermal variation in conditional layers of an enclosure. Most scientists recommend using no more than a value of 0.5 for the Fourier number when performing calculations on dynamic (transient) heat transfer. The value of the Fourier number is determined in order to acquire reliable calculation results with optimal accuracy. To compare the results of simulation with experimental research, a transient heat transfer calculation spreadsheet was created. Our research has shown that a Fourier number of around 0.5 or even 0.32 is not sufficient (\({\approx }17\,\%\) of oscillation amplitude) for calculations of transient heat transfer in a multilayered wall. The least distorted calculation results were obtained when the multilayered enclosure was divided into conditional layers with almost equal Fourier number values and when the value of the Fourier number was around 1/6, i.e., approximately 0.17. Statistical deviation analysis using the Statistical Analysis System was applied to assess the accuracy of the spreadsheet calculation and was developed on the basis of our established methodology. The mean and median absolute error as well as their confidence intervals has been estimated by the two methods with optimal accuracy (\({F}_{\mathrm{oMDF}}= 0.177\) and \(F_{\mathrm{oEPS}}= 0.1633\) values).     

The Antimicrobial Effect of Spice‐Based Marinades against Campylobacter jejuni on Contaminated Fresh Broiler Wings

The antimicrobial effect of spice‐based marinades against Campylobacter jejuni on inoculated fresh broiler wings was investigated. Experiments were carried out with 1 strain of C. jejuni and 6 marinades. Four experimental marinades were composed for the study and contained spices (thyme, rosemary, basil, marjoram, and so on) and different combination of bioactive compounds. Two marinades were commercial and contained spices (black pepper, sweet red pepper, and so on) and chemical additives (monosodium glutamate, sodium diacetate, calcium lactate), 1 commercial marinade was also enriched with bioactive compounds (linalool, cinnamaldehyde, lactic acid). Total aerobic bacterial count was examined to estimate the possible effect of tested marinades on the shelf‐life of marinated broiler wings. Study revealed that thyme‐based marinade was the most effective against C. jejuni on broiler wings and reduced the numbers of campylobacters by 1.04 log colony forming unit (CFU)/g (P ≤ 0.05) during storage for 168 h at 4 °C temperature. Moreover, it was more effective against C. jejuni than commercial marinade with 0.47 log CFU/g (P ≤ 0.05) reduction effect. Both experimental and commercial marinades had very similar effect on the total aerobic bacterial count. Although experimental and commercial marinades had different effect on pH of broiler wings, this parameter did not show a major impact on the antimicrobial effect of tested marinades (P ≥ 0.05). Our study shows that experimental natural thyme‐based marinade can reduce numbers of C. jejuni more effectively than tested commercial marinades.     

Investigation of hydrogen generation from sodium borohydride using different cobalt catalysts

Effective Co/Cu, CoB/Cu, and CoBM (M = Mo,Zn,Fe)/Cu catalysts were prepared on the copper surface by a simple electroless deposition method using a morpholine borane as a reducing agent in the glycine solution. The activity of the deposited catalysts was investigated for hydrogen generation from an alkaline sodium borohydride solution. It was determined that these synthesized catalysts demonstrated the catalytic activity for the hydrolysis reaction of NaBH₄. The lowest obtained activation energy (E_A) of the hydrolysis reaction of NaBH₄was 27 kJ mol^?1 for the CoBMo/Cu catalyst. The hydrogen generation rate of 15.30 ml min^?1 was achieved using CoBMo/Cu catalysts at 313 K and it increased ~3.5 times with the increase of temperature to 343 K. The highest hydrogen generation rate obtained by CoBMo/Cu films may be related to the hierarchical cauliflower-shaped 3D structures and the high roughness surface area. Moreover, the CoBMo/Cu catalyst showed an excellent reusability.     

Investigation of the changes in physical properties of PES/PVC fabrics after aging

The aim of this work was to investigate the physical and mechanical performance of architectural polyester (PES)–poly(vinyl chloride) (PVC) membranes exposed to different artificial aging conditions. Two commercially available architectural membranes were chosen as research objects. The durability of the PES/PVC fabrics was evaluated by the loss in mechanical performance, scanning electron microscopy, and X-ray diffraction analysis in order to understand the effect of the degradation agents on the surface of the membranes. The mechanical performance of the PES/PVC membranes was unchanged. Scanning electron microscopy images of the tested materials showed initial cracks after aging. The X-ray fluorescence analysis showed that at the time of aging, the amount of Cl and Si decreased slightly, while Ti decreased by half, and Ca by volume increased twice. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47523.     

Fast removal of Pb(II) and Cu(II) from contaminated water by groundwater treatment waste: impact of sorbent composition

ABSTRACT

A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe₂O₃, 7.4% P₂O₅, 7.4% CaO and 5.2% SiO₂. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions.     

Clinorotation Effect on Response of Cress Leaves to Red and Far-Red Light

Responses of cress (Lepidium sativum L.) seedling leaves to separate and simultaneous illumination with red (660 nm) and far-red (735 nm) light were studied under fast clinorotation (50 rpm) and usual gravity (1g) conditions. The monochromatic light emitting diodes (LEDs) have been used for illumination of seedlings from above. The growth and spatial orientation of leaves and the location of presumable gravisensors in petioles were analysed. Clinorotation in the dark promoted the radial expansion of leaf lamina and unfolding of leaves. It was shown that clinorotation in red light inhibited significantly the elongation of petioles as compared with that under the action of gravity force. Simultaneous red and far-red illumination promoted the growth of petioles under clinorotation, but did not affect the orientation of laminas, which remained the same as of the 1-g control ones. Red light, applied separately and simultaneously with far-red light, guided the bending of laminas as well as the unfolding of leaf petioles in both usual and clinorotation conditions. Histological and cytological analyses of petioles revealed the presence of movable amyloplasts in endodermic cells in proximal region of petioles. Comparison of intracellular positioning of amyloplasts in petioles of leaves grown under clinorotation and the action of gravity allows a presumption that these plastids may be identified as gravisensors of garden cress leaves. The obtained data imply that clinorotation and exposition to monochromatic red light or simultaneous illumination by red and far-red light affect the elongation of petioles of cress seedling leaves. Spectral components guide the unfolding of laminas in a gravity-independent manner.     

Electrodeposition of Sn and Co coatings from citrate solutions

Optimal conditions for Sn and Co codeposition were achieved in slightly acid citrate solutions containing no excess of ligand. Sn–Co coatings were deposited with amounts of Co ranging from 15 to 86 mass %. Bright deposits were obtained when the Co content exceeded 76%. These coatings may be considered as solid solutions of tin in -Co and -Co. The -Sn phase is predominant in the case of coatings containing less Co. Voltammograms of the partial processes of Sn(II) and Co(II) reduction may be described quantitatively with the proviso that SnL^2– and CoLH^– are electrically active complexes.     

XRD studies of electrochemically hydrided–dehydrided thin films of the alloy AZ31 and AZ31 with Ti

A magnetron sputtered thin films of the AZ31 alloy and AZ31 alloy with Ti capped with Pd were electrochemically hydrogenated and dehydrogenated in a 3 M KOH solution. A phase composition and structure of the films were studied by XRD. It has been determined that the behaviour of magnetron sputtered alloy AZ31 during electrochemical charging with hydrogen was alike that of pure Mg. The shift of the XRD peak Mg (0 0 0 2) to lower angles indicates that a hydrogen solid solution in the AZ31 alloy was formed along with MgH₂. When the AZ31 alloy with 18 at.% of Ti was electrochemically hydrogenated the whole film was transformed into hydride. The minor part of the hydride was in the nanocrystalline state with a structure of rutile and a major part of the hydride was in the amorphous state. After dehydrogenation only a part of the alloy recovered and the rest remained in the state of amorphous hydride. A positive shift of peak Pd (1 1 1) was observed in all of the XRD patterns for hydrogenated films. At least partially the shift should be associated with the compressive stresses in the top-cap layer of Pd, which arose due to the hydrogenation of the AZ31 alloy.     

Characteristics of Zinc Corrosion and Formation of Conversion Films on the Zinc Surface in Acidic Solutions of Cr(III) Compounds

The influence of the components of an acidic solution: Cr(III) nitrate-malonic acid-Co(II) salt and treatment conditions on zinc dissolution and formation of Chromate films as well as on their decorative and protective properties have been studied using the analytical, XPS, structural and accelerated corrosion test methods. An organic acid is the main component, which has an essential influence on zinc dissolution and formation of Chromate films as well as their decorative and protective properties. The influence of organic acid is directly related with the state of the Cr³⁺ ions in chromating solution. When the Cr³⁺ ions are in the form of hexaaquaions, the organic acid increases the quantities of the zinc dissolved and the Cr(III) deposited on the zinc surface (especially at 60°C). It also predetermines the formation of a thick, porous Chromate film with large cracks at 60°C. Its decorative and protective properties are rather poor. When Cr³⁺ ions are in the form of a complex with organic acid, the quantities of the zinc dissolved and the Cr(III) deposited on the zinc surface significantly decrease and thinner Chromate films with an even surface, good decorative appearance and high corrosion resistance are formed Decorative blue-bright Cr(VI)-free films with a slight iridescent tint, obtained in solution, containing Cr(III) nitrate (0.2), malonic acid (0.3) and Co(II) nitrate (0.02) mol dm^?3, at p H 1.6-2.0 at room temperature over 30–60 s, possess corrosion resistance (192–240 h in a salt spray chamber) similar to that of iridescent Chromate films, obtained in acidic Cr(VI) solution.