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Employee selection is a multi-criteria decision-making (MCDM) problem for selecting suitable applicants from a ready pool. The selection aims to make use of their knowledge, relevant skills, and other characteristics to perform a specific job. The aim of this study is to develop a systematic approach for selecting the best candidates among the air traffic controllers (ATCs) for aviation in Saudi Arabia. Three integrated methods were employed for decision-making in this study. First, a fuzzy decision tree was applied to determine the criteria weights, then the fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed to rank the attributes. In the last step, the Data Envelopment Analysis (DEA) was used to transform the qualitative variables into quantitative equivalences. A survey was conducted by national and international decision- makers to elicit the necessary information on the criteria and sub-criteria of the air traffic control system. The decision problem was formulated by employing five criteria and ten applicants. The relationship between the fuzzy TOPSIS and fuzzy-weighted average was very positive for decision-making. The outcomes of the fuzzy TOPSIS and DEA encouraged the development of a decision support system for the selection of ATCs.

The present study focuses on synthesis of silver nanoparticles (AgNPs) by employment of a green and facile synthesis method. Aqueous extract of Helichrysum arenarium was used as a reducing and capping agent. The bioreduction of silver particles was monitored using UV–Vis spectroscopy based on increase in color intensity led by surface plasmon resonance. SEM, TEM, FTIR, DSC, and XRD analyses were followed for characterization, divulging that the nanoparticles were thermally resistant in the size of approximately 20 nm with a quasi-spherical shape without any agglomeration. AgNPs possessed a nanocrystal form with presence of crystalline Ag. EDAX analysis was used to verify that the nanoparticles were silver as revealed by a typical optical absorption peak of metallic silver nanocrystallites. The AgNPs were shown to have strong antibacterial and antifungal effects on some foodborne pathogens. The method developed in this study could offer a green, facile biomimetic, and cost-effective method. [ABSTRACT FROM AUTHOR]

There has been an increasing interest in biocatalysts over the past few decades in order to obtain high efficiency, high yield, and environmentally benign procedures aiming at the manufacture of pharmacologically relevant chemicals. Lactic Acid Bacteria (LAB), a microbial group, can be employed as biocatalysts while performing asymmetric reduction of prochiral ketones. In this study, Leuconostoc mesenteroides N6 was used for the asymmetric bioreduction 1-indanone. And then, a novel and innovative face-centered design-based multi-objective optimization model was used to optimize experimental conditions. Also, the experimental design factors were defined as agitation speed, incubation period, pH, and temperature for optimization to acquire the maximum enantiomeric excess (ee) and conversion rate (cr) values. When using the face-centered design-based multi-objective optimization model, the optimum culture conditions corresponded to 96.34 and 99.42%, ee and cr responses, respectively, were pH = 5.87, incubation temperature = 35 °C, incubation period = 50.88 h, and agitation speed = 152.60 rpm. Notably, the validation experiment under the optimum model conditions confirmed the model results. This study demonstrated the importance of the optimization and the efficiency of the face-centered design-based multi-objective model. [ABSTRACT FROM AUTHOR]

Prochiral ketones can be effectively bio-reduced to chiral secondary alcohols by whole-cell biocatalysts, which are possible useful precursors to synthesize physiologically active chemicals and natural products. When whole-cell biocatalysts strains are used, bioreduction process can be influenced by various cultural factors, and it is vital to optimize these factors that affect selectivity, conversion rate, and yield. In this study, Weissella cibaria N9 was used as whole-cell biocatalyst for bioreduction of 1-(thiophen-2-yl)ethanone, and cultural design factors were optimized using a desirability function-embedded face-centered optimization model. For this, effects of pH (4.5–5.5–6.5, x1), (2) temperature (25–30–35 °C, x2), (3) incubation period (24–48–72 h, x3), and (4) agitation speed (100–150–200 rpm, x4) on two response variables; (1) ee (%) and (2) cr (%) were tested. Next, desirability function-embedded face-centered optimization model revealed that a pH of 6.43, a temperature of 26.04 °C, an incubation period of 52.41 h, and an agitation speed of 150 rpm were the optimum levels and the estimated ee and cr responses were 99.31% and 98.16%, respectively. Importantly, the actual experimental ee and cr responses were similar to the estimated values indicating the capability of the offered desirability function-embedded face-centered optimization model when using the optimum cultural conditions. [ABSTRACT FROM AUTHOR]