Authors:Viktória Kállai, Gábor L. Szepesi and Péter Mizsey
Chemical industry has a high demand for ethylene quantity, especially with high quality. This paper discusses dynamic simulation models of an ethaneethylene high-pressure cryogenic rectification column with Unisim Design process simulator software. Distillation is one of the most essential technologies in chemical industry, it is important that the operation of the procedure can be modeled not only in steady-state mode but also in a dynamic way. The goal during this study is to make simulations with system-controlling and to investigate the effect the disturbance on the behavior of the columns.
Authors:O. Ben Moussa, E. Rouissi, M. Boulares and M. Hassouna
Yoghurt is considered as a healthy food. Thus, it could convey functional and bioactive ingredients. Chia seeds are of great interest due to their ability to improve consumer health. In this study, chia seeds were added to stirred yoghurt at diﬀerent doses (1.5, 3, 4.5, or 6%). The eﬀects of chia seeds on physicochemical, microbiological, and sensory qualities were assessed during 28 days of refrigerated storage. The results showed that chia seeds slightly decreased post-acidiﬁcation, the lowest value was obtained in yogurt with 3% chia seeds (24°D), but syneresis rose signiﬁcantly (P<0.05) when 6% of chia seeds was added. Furthermore, chia seeds promote viability of yoghurt bacteria, and antioxidant activity reached 62.20±0.02% in yoghurt added with 1.5% chia seeds. However, proteolysis is not aﬀected. The eﬀects of chia seeds were not dose dependent as 4.5% and 6% did not follow trend. These ﬁndings were aﬃrmed by sensory characteristics. Thus, stirred yoghurt containing 1.5 or 3% of chia seeds proved to be the most adequate choices.
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.