Optimisation of drop size in countercurrent flow liquid-liquid extraction columns

Experimental data obtained in a pilot plant rotating disc contactor were used to obtain values of parameters for the hydrodynamic and mass transfer models representing column operation. The unique feature of the data was that drop size within the column did not vary appreciably with vertical position. Column performance measurements were therefore truly representative of the particular drop size generated. The models, with the resulting parameter values, were then used in design mode to determine column dimensions as a function of drop size. An optimum drop diameter of 0.20–0.25 cm is indicated for the toluene-acetone-water system.     

Ferric oxide/date seed activated carbon nanocomposites mediated dark fermentation of date fruit wastes for enriched biohydrogen production

Biohydrogen production from biomass waste, not only addresses the energy demand in a renewable manner but also resolves the safe disposal issues associated with these biowastes. Also, scalable and low-cost techniques to enhance biohydrogen production have gained more attraction and are highly explored. In this research work, date-palm fruit wastes have been studied for their biohydrogen production potential using Enterobacter aerogenes by dark fermentation. Hydrogen yield and productivity were improved through the addition of iron oxide nanoparticles (Fe₃O₄ NPs) and its date seed activated carbon nanocomposites (Fe₃O₄/DSAC) to the fermentation media. Studies on discrete inclusions of these NPs showed that the appropriate dosage of NPs promoted, while higher dosages repressed the hydrogen production performance. Optimal dosage and fermentation time was observed as 150 mg/L and 24 h for both the additives. Fe₃O₄/DSAC nanocomposites showed better hydrogen production enhancement than Fe₃O₄ NPs. Maximum hydrogen yield of 238.7 mL/g was obtained for the 150 mg/L nanocomposites, which was 65.7% higher than that of the standalone Fe₃O₄ NPs and three folds higher than the yield of the control run without any NPs inclusion (78.4 mL/g). Metabolites analysis showed that the hydrogen evolution followed the ethanol-acetate pathway. Formation levels of longer chain propionate and butyrate co-metabolites were significantly low in the presence of Fe₃O₄/DSAC than Fe₃O₄. The carbon support in the nanocomposites acted as an adsorbent-buffer, which favored the medium pH in-addition to the stimulatory effects of Fe₃O₄ NPs. Cell growth and specific hydrogenase activity analysis were also performed to supplement the hydrogen production results. Gompertz and modified Logistic kinetic models were employed for kinetic modeling of experimental hydrogen production values. The Fe₃O₄/DSAC nanocomposites exhibited significant application potential for the production of biohydrogen from date fruit wastes.     

A Note on the Two-Spring Tomlinson Model

In this note, quasistatic solutions of a two-mass-two-spring Tomlinson model for atomic force microscopy are derived, and are compared with the corresponding results of the single-spring Tomlinson model. It is clarified that the solutions of the two models are equivalent provided that the effective spring constant is correctly defined. It is also shown that modeling the onset of stick-slip motion in terms of the criteria defined by explicit tip and cantilever stiffness is the most convenient to investigate the effects of the tip-flexibility on the stick-slip motion.     

The behaviour of adhesively bonded beams versus their welded equivalent

The study aims to produce a design guide for the calculations of stresses and deflections of adhesively bonded beams fabricated from steel adherends using a structural epoxy adhesive. Such design calculations already exist for welded but not for bonded beams. Small models based on beams with a T-section profile, at various beam lengths, are formulated. A key to these calculations is the determination of the adhesive/adherend interface factors/coefficients, to correct the estimated values of stress and deflection from three-point bending conditions. This article presents the methodology for evaluating bonded beams in relation to equivalent welded (solid) beams. This includes mechanical testing, an analytical method based on beam and sandwich theory, and finite element techniques. Results from these techniques are presented and compared and values of the coefficients for T-section beams are determined.     

Dietary Plant Sterols Supplementation Increases In Vivo Nitrite and Nitrate Production in Healthy Adults: A Randomized,Controlled Study

A randomized, double‐blinded, placebo‐controlled and crossover study was conducted to simultaneously measure the effects, 3 h after consumption and after 4‐wk daily exposure to plant sterols‐enriched food product, on in vivo nitrite and nitrate production in healthy adults. Eighteen healthy participants (67% female, 35.3 [mean] ± 9.5 [SD] years, mean body mass index 22.8 kg/m²) received 2 soy milk (20 g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmityl esters (β‐sitosterol, 55%; campesterol, 29%; and stigmasterol, 23%). Nitrite and nitrate concentrations were measured in the blood plasma and urine, using stable isotope‐labeled gas chromatography‐mass spectrometry. L‐arginine and asymmetric dimethylarginine concentrations in blood serum were measured using commercially available enzyme immunoassays. Nitrite and nitrate concentrations in blood plasma (nitrite 5.83 ± 0.50 vs. 4.52 ± 0.27; nitrate 15.78 ± 0.96 vs. 13.43 ± 0.81 μmol/L) and urine (nitrite 1.12 ± 0.22 vs. 0.92 ± 0.36, nitrate 12.23 ± 1.15 vs. 9.71 ± 2.04 μmol/L) were significantly elevated after 4‐wk plant sterols supplementation Placebo and 3‐h treatments did not affect the blood plasma and urinary concentrations of nitrite and nitrate. Circulating levels of L‐arginine and asymmetric dimethylarginine were unchanged in the placebo and treatment arms. Total plant sterols, β‐Sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4‐wk treatments compared to the placebo and 3‐h treatments. Blood plasma nitrite and nitrate concentrations correlated significantly with the plasma total and specific plant sterol concentrations. Our results suggest that dietary plant sterols, in the combination used, can upregulate nitrite, and nitrate production in vivo.     

Green technology of liquid biphasic flotation for enzyme recovery utilizing recycling surfactant and sorbitol

Liquid biphasic flotation (LBF) system has been recognized as an efficient, green, economically sustainable and biocompatible technique for biomolecules separation and purification. The main drawbacks of the conventional process of biomolecules separation are expensive production cost, utilization of phase components that are inefficiently recycled and global pollution due to high chemical consumption and wastage. In this paper, a novel approach of LBF system for lipase recovery utilizing recycling phase components comprising surfactant and xylitol was investigated. The scope of this study focuses on pollution prevention as well as clean and environmentally friendly process for enzyme extraction via LBF. The green process proposed in this study uses phase-forming components that have recovery and recycling abilities for minimal use of chemicals for enzyme extraction. This novel method utilized Triton X-100 and xylitol for lipase extraction from Burkholderia cepacia. A few parameters were optimized to obtain high lipase separation efficiency and yield. Based on the ideal conditions of LBF, the average lipase separation efficiency and yield are 86.46 and 87.49%, correspondingly. Phase components recycling were proposed in order to reduce the chemicals consumption in LBF system. Upscaling of the recycling study exhibited consistent result with the laboratory scale. It was found that 97.20 and 98.67% of Triton X-100 and xylitol were recovered after five times of recycling and that a total of 75.87% of lipase separation efficiency was obtained. Recovery and recycling of phase components in the extraction process are established as the principal green chemistry method, which yields high separation efficiency and is economically feasible on an industrial scale.     

Economic and environmental analysis of PHAs production process

Following the growing demand to improve both economic and environmental performance of PHAs production, the research focused on the evaluation of the economic and environmental performance of PHAs production process via aqueous two-phase extraction (ATPE). Thus, the process analysis of two processes with different PHAs purification and recovery strategies (which are with and without thermoseparating ATPE as primary purification step) was performed. Using the basis of 9000 tons PHAs production per year and 7920 operating hours, the process with thermoseparating ATPE as primary purification step standout in terms of both economic and environmental performance. PHA production cost of 5.77 US$/kg with a payback period of fewer than 4 years and ROI of 25.2% was achieved. The results showed that most of operating cost is contributed by facility-dependent cost and raw material cost, while the main contributor to raw material cost is carbon source. The insight from sensitivity analysis has demonstrated that the economic performance is sensitive to the fluctuation in surfactant cost. This proved that utilizing thermoseparating ATPE as primary recovery step not only helps to reduce chemical consumption, it also minimizes downstream equipment cost and wastewater treatment cost.     

Intelligent ubiquitous IT policy and its industrial services

The core bases of intelligent ubiquitous computing environments are ubiquitous network infrastructure and the related services. Telecommunication service industry includes such ubiquitous network infrastructure and most of related services, and it leads to simultaneous growth of network, terminal, software and contents etc., by placing at the top of value chain of IT industry. In this special issue, we have discussed current IT-related issues, policy trends and new industrial services which will lead to successful transfer toward intelligent ubiquitous society which is a new paradigm of future.     

Investigation of Semiconductor Quantum Dots for Waveguide Electroabsorption Modulator

In this work, we investigated the use of 10-layer InAs quantum dot (QD) as active region of an electroabsorption modulator (EAM). The QD-EAM is a p-i-n ridge waveguide structure with intrinsic layer thickness of 0.4 μm, width of 10 μm, and length of 1.0 mm. Photocurrent measurement reveals a Stark shift of ~5 meV (~7 nm) at reverse bias of 3 V (75 kV/cm) and broadening of the resonance peak due to field ionization of electrons and holes was observed for E-field larger than 25 kV/cm. Investigation at wavelength range of 1,300–1320 nm reveals that the largest absorption change occurs at 1317 nm. Optical transmission measurement at this wavelength shows insertion loss of ~8 dB, and extinction ratio of ~5 dB at reverse bias of 5 V. Consequently, methods to improve the performance of the QD-EAM are proposed. We believe that QDs are promising for EAM and the performance of QD-EAM will improve with increasing research efforts.