Authors:I. K. Bedaida, S.H.D. Masry, B. Mamache, M.G. Shehata, L. Benammar, and A. Ayachi
This study describes the antistaphylococcal mechanism of the ethanolic extract of Algerian propolis on Staphylococcus aureus ATCC 25923. To investigate the underlying mechanism of action of the ethanolic extract of propolis, bacteriolysis, bacterial death, leakage of potassium, proteins, nucleic components, and scanning electron microscopic studies were conducted. The results showed that the minimum inhibitory concentration (MIC) of ethanolic extract of propolis against Staphylococcus aureus ATCC 25923 was 39 μg ml–1. The extract displayed signiﬁcant bactericid activity against S. aureus in a time and concentration dependant manner. Its mode of action was evident from the increase of K+ eﬄux and nucleotide leakage. These results were conﬁrmed by Scanning Electron Microscopy (SEM) that showed remarkable morphological and ultrastructural changes in S. aureus after exposure to 1MIC and 2MIC concentrations. The overall study contributed to the understanding of the antistaphylococcal mechanism of ethanolic extract of propolis. It emphasizes its potential to be used as an important natural bio-preservatives in food products.
Authors:I. Kaur, N. Chawla, A.S. Dhatt, and M. Kaur
In this study, thirty onion (Allium cepa L.) genotypes grown in sub-tropical region of India were analysed for diﬀerent physico-chemical attributes. There were signiﬁcant diﬀerences among genotypes, and the onion genotypes showed a tendency to be classiﬁed according to diﬀerent colours. The cultivars of the same colour exhibited similar tendencies in terms of accumulating most of the analysed components. About 1.78 fold variation in dry matter (%) and 2 fold variation in fresh weight per bulb were recorded among coloured onions. Red genotype D-888-B possessed maximum contents of TS and NRS, while the yellow coloured genotype POH-5 accumulated highest RS and lowest NRS contents. Maximum values of fructans (3.68 g/100 g DW), AIS (6 g/100 g DW), protein (10.61 g/100 g DW), and FAA (4.24 g/100 g DW) were also found in red coloured genotypes D-715-B, D-97-B, PR-305, and D-PS-121-B, respectively. Proline content in diﬀerent genotypes was found to vary about 6.9 fold. The correlation studies showed a positive relationship between most of the quality parameters. Our results suggested that red group genotypes were better than yellow and white groups for all the studied parameters except for RS, which makes red genotypes more suitable for processing purposes.
Authors:D. Koren, B. Hegyesné Vecseri, and G. Kun-Farkas
There are numerous scientiﬁc publications about the folate content of several types of beers available in commercial trade, but there is limited information about the eﬀect of raw materials and technological steps of brewing on folate content. In this study the aim was to investigate diﬀerent raw materials and the evolution of folate content during laboratory and pilot scale brewing. For the determination of folate content of diﬀerent malts, three types of barley malts (Pilsner, Caramel, and Coloring), wheat malt, rye malt, and oat malt were analysed. For the study of the evolution of folate content during the brewing process, worts were produced on laboratory and pilot scale. Among malts, Pilsner type barley malt had the highest folate content (44.7 μg/100 g d.m.). During brewing the protein rest seemed to dissolve the majority of the folate content, and with the increasing temperature of the β- and α-amylase rests there was a further dissolution. Filtration and sparging did not have negative eﬀect on folate concentration related to the extract content of the wort. Hop boiling had no negative eﬀect on folate content, folate seemed to be stable during the one-hour boiling. Natural folate of barley malt seemed to be stable through the technological steps of brewing, oﬀering the possibility to produce a foodstuﬀ with high natural folate content.
This study aims to experimentally investigate the nucleate pool boiling heat transfer performance of magnesium oxide nanoparticles MgO based deionized water nanofluid at the atmospheric pressure condition. Dilute volumetric concentrations within a range of 0.001% to 0.01% Vol. were used to examine the pool boiling heat transfer performance represented by pool boiling curve, and pool boiling heat transfer coefficient. The heating element was a horizontal copper heated tube with a typical diameter 22 mm submerged inside the cubic boiling chamber. Efforts have been made to measure the surface temperatures along the heated tube to ensure the proper and accurate heat transfer coefficient calculations in this work. The results indicated that the pool boiling heat transfer coefficient enhancement ratio (PBHTC /PBHTC ) was intensified for volume fractions i.e. 0.001%, 0.004%, and 0.007% Vol. while it was degraded for volume concentrations i.e. 0.01%, and 0.04% Vol. compared to deionized water as baseline case.
Authors:Ivan V. Abramov, Pavel V. Lekomtsev, Аlexander V. Romanov, Аndrey V. Buchkin, Zarina S. Saidova, and Zoltan Orban
The paper presents an experimental research on anchoring devices developed for the pre-tensioning of fiber reinforced polymer tendons in the stress range between 40 and 70% of tensile strength. The technique of testing, the criteria of assessing the load capacity and the influence of preloading applied on the anchor wedges on the initial tendons slippage are described. The optimal technical configurations of the anchoring device have been obtained, including parameters regarding the necessary prior anchorage of the tendon ends based on the strength properties of the tendon bar and the requirements to avoid slippage during the tensile tests.
The propagation of an ultra-short light pulse is studied in the framework of scalar diffraction theory. Light pulses are focused by different types of wavy parabolic surfaces. The temporal-spatial behavior of the two-dimensional wave field is computed in the vicinity of the focal plane. It is shown that the slightly perturbation from the perfect parabolic shape leads a space-time dispersion of the pulse in the neighborhood of the focus.
Authors:J. Schuster, T. Kimáková, V. Kukačka, M. Belovičová, and V. Bencko
The behaviour regarding the ﬂuid intake in adolescents and young adults is an important issue, since these data may provide information about the health consciousness of the next generation. Inappropriate daily beverages intake for a long period can have adverse eﬀects on human health. Positive eﬀects of maintenance of good hydration are known in the prevention of chronic diseases like urolithiasis, bladder or colon cancer, hypertension, obesity, or constipation. In the present study, we examine the various factors of beverage intake by university students. Data from 3020 students of the Czech and Slovak universities were collected in 2016–2018 to evaluate their daily ﬂuid intake and the characteristics of beverage consumptions. We found that gender, country, frequency of daily water intake, nutrition literacy, and some other factors inﬂuence whether a student reports having a daily water intake of more than 1.5 litres. Our respondents have preferences for beverages, based on taste and health eﬀects primarily, prices and availability were secondary. We present the suggestions for a more balanced beverage intake for the studied age group.
Examining a human movement can provide a wealth of information about a patient’s medical condition. The examination process can be used to diagnose abnormal changes (lesions), ability development and monitor the rehabilitation process of people with reduced mobility. There are several approaches to monitor people, among other things with sensors and various imaging and processing devices. In this case a Kinect V2 sensor and a self-developed LabView based application was used, to examine the movement of the lower limbs. The ideal gait pattern was recorded in the RoboGait training machine and the measured data was used to identify the phases of the human gait. During the evaluation, the position of the skeleton model, the associated body joints and angles can be calculated. The pre-recorded ideal and natural gait cycle can be compared.
With the self-developed method the pre-recorded ideal and natural gait cycle can be compared and processed for further evaluation. The evaluated measurement data confirm that a reliable and mobile solution for gait analysis has been created.
Authors:Andrej Šoltész, Dana Baroková, Zinaw Dingetu Shenga, and Michaela Červeňanská
Presented paper deals with the hydraulic assessment of groundwater flow in the area affected by the realization of the hydraulic gate on the Klátov branch and in the adjacent territory of a dike, which is located on the right-side of Little Danube. This hydraulic assessment is part of the project of the Slovak Water Management Enterprise, which also aims to increase the height and seal the dike on the right-side of the Little Danube. Generally, the project is divided into three phases (Phase I, II and III) to implement different technical measures to protect the area from flooding. The assumption for the execution of the technical measures of the mentioned three project phases is a continuous flood protection of part of the Žitný ostrov area around the Little Danube and the Klátov River branch in the reach from Kolárovo to Jahodná town. Therefore, a 3D mathematical model was created to simulate groundwater flow by changing boundary conditions of surface water flow during flood periods.
Authors:Abbas Al-Hdabi, Mohammed K. Fakhraldin, Rasha A. Al-Fatlawy, and Tawfek Sheer Ali
Ignition of waste paper sludge at elevated temperatures to produce electricity in power generation plants utilizing fluidized bed combustion generates paper sludge ash. Due to the high concentration of lime and gelignite in paper sludge ash, it is expected that it will play a vital role as a cementitious material. This paper investigates the use of paper sludge ash to improve the mechanical properties of the granular materials, which are suitable to subbase course for road and building constructions. Also, a comparison study with the use of Portland cement as an additive to granular materials has been covered. The mechanical properties were evaluated by conducting the California bearing ratio test for the two adopted methods. Moreover, the compressive strength of the samples using paper sludge ash and cement are investigated. In accordance to the California bearing ratio test, 4% paper sludge ash was indicated as the optimum ash content at which the California bearing ratio value increased by 173% and 111% in comparison with untreated material and 6% cement, respectively. On the other hand, and by means of the compressive strength, the granular materials with 4% paper sludge ash has compressive strength higher than those with 6% cement.