Electrocoagulation of azo dye production wastewater with iron electrodes: process evaluation by multi‐response central composite design

Central composite design was used to optimise electrocoagulation of CI Acid Blue 193 production wastewater. By applying a response surface quadratic model, the main process manipulators (effluent chemical oxygen demand, initial pH, electrical current density and treatment time) were optimised to achieve maximum colour, chemical oxygen demand and total organic compound removals. Analysis of variance indicated that the established polynomial regression models were significant and fitted the experimental data satisfactorily.     

时间对小茴香挥发油成分的影响

本文报道用气相色谱-质谱联用技术分析了刚采收、采收后一年及两年的小茴香挥发油成分，共分离鉴定出21个组分，主要成分为反式茴香脑、柠檬烯、冰片及小茴香酮等。小茴香放置两年后挥发油总量减少29．19％，且挥发油的化学组分及相对含量均有较显著的变化。     

CFRP Effect on the Buckling Behavior of Dented Cylindrical Shells

Considering that the use of thin-walled shells is expanding every day, it is important to examine the problem of instability in this form of structure. Many steel structures such as high-water tanks, water and oil reservoirs, marine structures, and pressure vessels, including shell elements, are under stress tension. In addition, shell elements are subject to instability owing to the loads applied. Ten thin-walled cylindrical shell specimens in two groups with different dent depths of t_c and 2t_c, and the different dent number subject to uniform external pressure were tested in the present research (t_c is the thickness of cylindrical shell). The samples were modified to include either one or two dent line with amplitudes of h/3 in height (h the height of cylinder shell). Moreover, CFRP Strips on the dent depth was used in one of the groups. The results of testing under different theories and codes are compared.

     

Mycoflora and aflatoxin contamination in shelled pistachio nuts

A total of 143 pistachio nut samples collected during harvest, storage and processing were examined for mould growth and aflatoxin production. The mould count was in the range of 10³?10⁴ cfu g^?1 and 10⁵?10⁶ cfu g^?1 for the harvest and storage samples, respectively. The growth of Aspergillus flavus was 38-5-39-5% on the surface of the shells and 6–16% on the kernels without aflatoxin production. The contamination level of A flavus varied among samples collected from different regions. Peeling off the soft shell of pistachio nuts by hand reduced the contamination risk of A flavus to kernels. The predominant flora on stored pistachio nuts were Aspergillus, Penicillium, Cladosporium, Rhizopus, while the genera of Ulocladium, Trichothecium, Aureobasidium and Eurotium were less frequent. Thirty-five percent of the A flavus isolates produced aflatoxins on synthetic media.     

Ultrasound assisted synthesis of Gd and Nd doped ceria electrolyte for solid oxide fuel cells

In this study, the ceramic powders of Ce_1?xGd_xO_2?x/2 and Ce_1?xNd_xO_2?x/2 (x=0.05, 0.10, 0.15, 0.20 and 0.25) were synthesized by ultrasound assisted co-precipitation method. The ionic conductivity was studied as a function of dopant concentration over the temperature range of 300–800 °C in air, using the impedance spectroscopy. The maximum ionic conductivity, σ_800 °C=4.01×10^?2 Scm^?1 with the activation energy, E_a=0.828 kJmol^?1 and σ_800 °C=3.80×10^?2 Scm^?1 with the activation energy, E_a=0.838 kJmol^?1 were obtained for Ce_0.90Gd_0.10O_1.95 and Ce_0.85Nd_0.15O_1.925 electrolytes, respectively. The average grain size was found to be in the range of 0.3–0.6 μm for gadolinium doped ceria and 0.2–0.4 μm for neodymium doped ceria. The uniformly fine crystallite sizes (average 12–13 nm) of the ultrasound assisted prepared powders enabled sintering of the samples into highly dense (over 95%) ceramic pellets at 1200 °C (5 °C min^?1) for 6 h.     

Multinuclear Cu(II) Schiff Base Complex as Efficient Catalyst for the Chemical Coupling of CO2 and Epoxides: Synthesis, X-ray Structural Characterization and Catalytic Activity

Abstract  

The synthesis, X-ray structure, spectroscopic and catalytic properties of sterically hindered Schiff-base ligands (L₁H = N-[allylamine]-3,5-di-tert-butyl salicylaldimine, L₂H=N-[2-amino-5-methyl pyridine]-3,5-di-tert-butyl salicylaldimine and L₃H=N-[2-amino-6-methyl pyridine]-3,5-di-tert-butyl salicylaldimine), and their mononuclear Cu(II) complex for L₁H with multinuclear Cu(II) complexes for L₂H and L₃H, were described. The copper(II) complexes of these ligands were synthesized by treating an methanolic solution of the appropriate ligand with an appropriate amount of CuCl₂·2H₂O. The ligands and their copper(II) complexes were characterized by FT-IR, UV–Vis, ¹H-NMR, elemental analysis, measurement of room temperature magnetic moment, and X-ray structural determination. The reaction of the L₂H and L₃H ligands in a 1:1 mol ratio with CuCl₂·2H₂O afforded ionic copper metal(II) complexes in the presence of NEt₃. The Cu(II) metal complexes tested as catalysts for the formation of cyclic organic carbonates from carbon dioxide and liquid epoxides which served as both reactant and solvent. [Cu₃(L₂)₄]Cl₂·CuCl₂ complex which has 5-methyl substituent on the pyridine ring showed high catalytic activity for chemical coupling carbon dioxide with epoxides (propylene oxide (PO), epichlorohydrine (EC) and 1,2-epoxy butane (EB)) selectively.     

Investigation of the elastic properties of poly (methyl methacrylate) reinforced with graphene nanoplatelets

The technique for synthesis of poly (methyl methacrylate) (PMMA) by atom transfer radical polymerization has been strengthened by using graphene nanoplatelets (GNPs) to enhance the elastic properties of the polymer. In order to improve practical, economical and mechanical performance, the requirements for effective implementation of production control as a smart bulk polymer nanocomposite were determined for cost-effective bulk production. Three-dimensional inspection (using an ultrasound interrogation method for the whole volume under test) confirmed the synthesis of the nanocomposite to be free of agglomeration and bubbles. As a result of this elimination of defects, an enhancement in compressive strength of 42.7% was achieved and the Rockwell hardness was increased by 19.9% through the addition of GNPs at 2 wt% by mass. The deformation and mechanical failure properties have been characterized in the mechanical enhancement of the polymer nanocomposite. Elastic parameters determined using ultrasound testing identified that changes in the structural features following the addition of these GNPs were uniquely connected to the enhancements in these elastic parameters (such as Young's modulus, Poisson's ratio, shear modulus, and microhardness) of the PMMA/GNPs nanocomposite.     

Visible light-induced degradation of indigo carmine over ZnFe2O4/Tannin/ZnO: Role of tannin as a modifier and its degradation mechanism

Design and usage of efficient visible light photocatalytic systems for wastewater treatment and degradation of organic dyes are of remarkable interest in the fields of environmental protection. In this study, magnetic ZnFe₂O₄, ZnFe₂O₄/ZnO, Tannin/ZnFe₂O₄ and Tannin/ZnFe₂O₄/ZnO nanocomposites with interfacial contact have been synthesized. The photocatalytic efficiencies of as-obtained samples are analyzed by the degradation of indigo carmine in aqueous solution under UV and visible-light. The degradation ratios of IC are 82% and 99% of IC over the Tannin/ZnFe₂O₄/ZnO under the both of UV light and visible light for 90 min, respectively. And after five times recycling, the photocatalytic performance of IC presence the Tannin/ZnFe₂O₄/ZnO can even reach nearly 89.79%. The results demonstrate that the Tannin/ZnFe₂O₄/ZnO exhibits great photocatalytic efficiency for indigo carmine (IC) compared to their constituent photocatalysts and easy separation from dye solution by magnet. The synergistic interactions between ZnFe₂O₄, tannin and ZnO prolonged lifetime of photoexcited carriers leading to greater absorption in both UV and visible light. This nanocomposite was beneficial for separating the photogenerated charge carriers and facilitating electron transfer. Tannin has a decisive role for increasing the photocatalytic performance of ZnFe₂O₄ due to the abundant units of phenolic groups in tannin molecules. ZnFe₂O₄ makes the Tannin/ZnFe₂O₄/ZnO magnetically separable in a system. This work presents new insights that tannin molecules function as great modifier to improve very impactful tannin-modified magnetic photocatalysts in removing environmental contamination.     

Dynamic oscillatory shear properties of O/W model system meat emulsions: Linear viscoelastic analysis for effect of temperature and oil concentration on protein network formation

Effects of oil concentration (57.50%, 58.75%, 60.00% and 61.25%) and temperature (5, 10 and 15 °C) on O/W model system meat emulsions were analyzed using oscillatory dynamic shear tests, allowing all emulsion systems to be characterized as linear viscoelastic solids exhibiting a pseudoplastic flow. The emulsion systems were characterized as weak gel-like macromolecular dispersions with G′ much greater than G″, exhibiting a plateau region. A modified Cox-Merz rule was applicable using shift factors. Frequency dependence of complex modulus (G^∗) was studied to measure strength of cross-linking protein network of the emulsion systems by calculating a practically constant order of the relaxation function (α = 0.10) and a concentration dependent stiffness parameter (A_α) using Friedrich and Heymann theory. It was concluded that the viscoelastic characteristics and strength of the emulsion systems increased with increasing oil level, but decreased with temperature. Different mathematical models were successfully constructed to predict the rheological parameters.     

Stress relaxation/creep compliance behaviour of kashar cheese: Scanning electron microscopy observations

In this study, uniaxial and creep analyses were used to characterise stress relaxation and creep compliance behaviour of kashar cheese as a function of different compression (1.5, 3.0, 4.5, 6.0 and 7.5 mm) and stress (12.25, 24.50, 36.75, 49.00 and 61.25 kPa) levels. For this purpose, mechanical simulation models, namely generalised Maxwell, Nussinovitch, Peleg and Burger models were used to simulate the viscoelastic behaviour of kashar cheese as a function of different compression and stress levels. The results revealed that the compression levels could remarkably change internal structure and deformation properties of kashar cheese. Stress relaxation test demonstrated that kashar cheese showed more elastic behaviour, namely higher resistance to deformation at higher compression levels. Creep tests showed that rigidity of kashar cheese decreased as the stress level applied increased. Scanning electron microscopy (SEM) images showed that compression resulted in a less homogeneous protein matrix, an interrupted casein/fat network, and destroyed fat globules by forcing them to exude from the cheese surface. These results should be useful for dairy industry.