Potential of pulsed electric field to control Aspergillus parasiticus,aflatoxin and mutagenicity levels: Sesame seed quality

Seed processing technologies are essential for seed safety and functionality through protection of physicochemical quality, pathogen inactivation, aflatoxin detoxification and alleviation of mutagenicity. Design of a pilot-scale unit of pulsed electric fields (PEF) to treat sesame seeds with respect to quality parameters, Aspergillus parasiticus inactivation and aflatoxin reduction as well as alleviation of aflatoxin mutagenicity were prompted in this study. PEF energy ranged from 0.97 to 17.28 J achieved maximum reductions of peroxide value and acidity number of 67.4 and 85.7%, respectively, and did not change color L*, a*, b* and hue values. A 60% reduction of A. parasiticus counts occurred at the maximum PEF energy. Aflatoxins G1, G2, B1, and B2 contents decreased by 94.7, 92.7, 86.9, and 98.7%, respectively. Except for the samples treated by 2.16 J with 100 μg/plate and by 6.80 J with 10 μg/plate, PEF treatment provided elimination of aflatoxin mutagenity. It is concluded that PEF treatment can be used to treat sesame seeds with preservation of physicochemical properties, inactivation of A. parasiticus and decomposition of aflatoxins with reduced mutagenicity.     

Dynamic stability of a shaft system connected through a Hooke's joint

Dynamic stability of the torsional vibrations of a shaft system consisting of two torsionally elastic shafts interconnected through a Hooke's joint is investigated by means of a two degree-of-freedom model. The linearized equations of motion are shown to consist of a set of Mathieu-Hill equations and stability of their solutions is analyzed by means of a monodromy matrix method. Results are presented in the form of stability charts constructed on various parameter planes visualizing the effect of various selected pairs of system parameters on the stability.     

The influence of nitrogen doping on reduced graphene oxide as highly cyclable Li-ion battery anode with enhanced performance

A straightforward, one-step route has been established to fabricate reduced- (rGO) and nitrogen-doped reduced graphene oxide (NrGO) with remarkable lithium-ion storage properties. The graphene oxide (GO) was synthesized as starting material by improved Hummers’ method. Thereafter, thermally annealing GO with NH₃ at elevated temperature to synthesize NrGO was yielded a more open structure with nitrogen sites suitable for enhanced Li intercalation. NrGO exhibited a reversible capacity of 240 mAhg^?1 at 10 Ag^-1 after 500 cycles with 90% capacity retention, which is the best result achieved among graphene oxide-based anodes at this current density. In contrast to rGO, NrGO cells exhibited a gradually increasing capacity profile, reaching up to 114% of the initial capacity at 0.1, 2, and 10 Ag^-1 current densities. Results showed that high occupancy of pyridinic N within NrGO enhanced battery performance and cell kinetics upon cycling which offers long-time operability at high current density.     

Friction and Wear Characteristics of Haynes 25, 188, and 214 Superalloys Against Hastelloy X up to 540 <Emphasis Type="Bold">°</Emphasis>C

As demand for more power increases, compression ratios, and operating temperatures keep rising. High speeds combined with high temperatures make turbomachinery sealing applications even more challenging. In order to confirm sufficient service life material pairs should be tested under conditions similar to engine operating conditions. This study presents high temperature friction and wear characteristics of cobalt/nickel superalloys, Haynes 25 (51Co–10Ni–20Cr–15W), Haynes 188 (39Co–22Ni–22Cr–14W), and Haynes 214 (75Ni–16Cr–3Fe–0.5Mn) sheets when rubbed against Hastelloy X (47Ni–22Cr–18Fe–9Mo) pins. Tests are conducted at 25, 200, 400, and 540 °C with a validated custom design linear reciprocating tribometer. Sliding speed and sliding distance are 1 Hz and 1.2 km, respectively. Friction coefficients are calculated with friction force data acquired from a load cell. Wear coefficients are calculated through weight loss measurements. Results indicate that Haynes 25 (H25) has the lowest friction coefficients at all test temperatures. Above 400 °C, H25 and Haynes 188 (H188) exhibit the best wear resistance. Protective cobalt oxide layers are formed on the H25 and H188 at 540 °C in addition to nickel, chrome, and tungsten oxides. Although, it has better oxidation resistance, Haynes 214 has relatively higher wear rates than other tested materials especially at low temperatures. However, its wear performance improves beyond 200 °C.     

Screening,Molecular Cloning,and Biochemical Characterization of an Alcohol Dehydrogenase from Pichia pastoris Useful for the Kinetic Resolution of a Racemic β‐Hydroxy‐β‐trifluoromethyl Ketone

The stereoselective synthesis of chiral 1,3‐diols with the aid of biocatalysts is an attractive tool in organic chemistry. Besides the reduction of diketones, an alternative approach consists of the stereoselective reduction of β‐hydroxy ketones (aldols). Thus, we screened for an alcohol dehydrogenase (ADH) that would selectively reduce a β‐hydroxy‐β‐trifluoromethyl ketone. One potential starting material for this process is readily available by aldol addition of acetone to 2,2,2‐trifluoroacetophenone. Over 200 strains were screened, and only a few yeast strains showed stereoselective reduction activities. The enzyme responsible for the reduction of the β‐hydroxy‐β‐trifluoromethyl ketone was identified after purification and subsequent MALDI‐TOF mass spectrometric analysis. As a result, a new NADP⁺‐dependent ADH from Pichia pastoris (PPADH) was identified and confirmed to be capable of stereospecific and diastereoselective reduction of the β‐hydroxy‐β‐trifluoromethyl ketone to its corresponding 1,3‐diol. The gene encoding PPADH was cloned and heterologously expressed in Escherichia coli BL21(DE3). To determine the influence of an N‐ or C‐terminal His‐tag fusion, three different recombinant plasmids were constructed. Interestingly, the variant with the N‐terminal His‐tag showed the highest activity; consequently, this variant was purified and characterized. Kinetic parameters and the dependency of activity on pH and temperature were determined. PPADH shows a substrate preference for the reduction of linear and branched aliphatic aldehydes. Surprisingly, the enzyme shows no comparable activity towards ketones other than the β‐hydroxy‐β‐trifluoromethyl ketone.     

Quinoxaline derivatives as long wavelength photosensitizers in photoinitiated cationic polymerization of diaryliodonium salts

The present paper is focused on visible light initiated cationic polymerizations. Photoinitiated polymerization of representative vinyl ether and oxirane monomers using two quinoxaline derivatives; namely (2-(2,3-dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and 2,3,5,8-tetra(thiophen-2-yl)quinoxaline (TTQ) are studied. Novel dyes based on the quinoxaline skeleton are employed as efficient photosensitizers in cationic photopolymerizations. Polymerizations were initiated at room temperature upon irradiation with long-wavelength UV and visible lights in the presence of diphenyliodonium hexafluorophosphate (Ph₂I⁺PF₆^?). The progress of the polymerizations was monitored by optical pyrometry (OP). Solar irradiation is also employed to carry out the cationic polymerization of a diepoxide monomer in the presence of air.     

Projection based method for segmentation of human face and its evaluation

We detect facial features and then circumscribe each facial feature with the smallest rectangle possible by using vertical and horizontal gray value projections of pixels. The result is evaluated with respect to the manually located enclosing rectangle on the images of a publicly available database.     

Division of the genitofemoral nerve and late orchiectomy: effects on the contralateral testis in ipsilateral testicular torsion

Unilateral torsion of the spermatic cord has been demonstrated to damage the contralateral testis; however, the pathogenesis has not yet been examined in detail. The purpose of this study was to evaluate the influence of unilateral torsion on the contralateral testis in rats by performing ipsilateral division of the genitofemoral nerve (GFN) and/or late orchiectomy. Male 25-day-old, prepubertal Wistar albino rats were divided into five groups: (1) sham operation; (2) unilateral testicular torsion; (3) simultaneous unilateral testicular torsion and ipsilateral GFN division; (4) unilateral testicular torsion and orchiectomy on the 4th day after torsion; and (5) simultaneous unilateral testicular torsion and GFN ipsilateral division, and orchiectomy on the 4th day after torsion. Torsions performed were 720 degrees, all on the right testes. On day 55 after torsion, which represents the early postpubertal period of the rat, the contralateral testes were removed. Tubular biopsy score (TBS) was calculated, and seminiferous tubular diameters (STD) were measured. Student's t-test was used for statistical analysis. There was no contralateral testicular damage in the control group, but in all of the study groups destructive changes were found in the left gonad after torsion of the right testicle. The mean TBS of the study groups was higher than that of the control group. STD values were lower in the study groups, but the differences were not statistically significant between groups. In prepubertal rats, unilateral torsion causes histologically measurable changes in the contralateral testis. Ipsilateral division of the GFN and late orchiectomy did not cause any significant alterations in terms of contralateral damage. Further investigations are needed to determine the role of the GFN in testicular torsion.     

A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species （Se（Ⅳ）, Se（Ⅵ）） at trace levels in natural lake and river water samples

A novel catalytic kinetic method is proposed for the determination of Se(IV), Se(VI), and total inorganic selenium in water based on the catalytic effect of Se(IV) on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2–20 and 20–200 μg·L⁻¹ of Se(IV) for the fixed-time method at 30°C. The experimental and theoretical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L⁻¹ for the fixed-time method (3 min). All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se(IV) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations (RSDs) for ten replicate measurements of 2, 10, and 20 μg·L⁻¹ of Se(IV) change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L⁻¹ of Se(VI) change between 0.49% and 1.61%. Analyses of a certified standard reference material (NIST SRM 1643e) for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se(IV), Se(VI), and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se(VI) to Se(IV).     

Solar energy-economic growth nexus in top 10 countries with the highest installed capacity

ABSTRACT

This paper investigates the relationship between solar energy production and economic growth for top 10 countries with the highest installed solar energy production capacity as of 2017 (China, the USA, Japan, Germany, Italy, India, the UK, France, Australia, and Spain, respectively) using data over the period 1999–2015. For this purpose, the paper employs panel cointegration and causality methods that are robust to cross-sectional dependence. The findings imply that the coefficient of solar energy is insignificant in the empirical model and that there is no causality between solar energy and GDP, indicating the neutrality hypothesis prevails for solar energy. Theoretical and practical implications are also discussed.