Phytate Hydrolysis by Phytase in Cereals; Effects on In Vitro Estimation of Iron Availability

Phytate (inositol hexaphosphate) hydrolysis by endogenous and exogenous phytases was studied for their effect on increasing iron availability in cereals. Wheat bran and whole meal flours of rye and oats were soaked at optimal conditions for phytase activity (55°C, pH 5) for different time intervals. Phytate and its degradation products were determined by HPLC and related to iron solubility under simulated physiological conditions. Small amounts of phytate (< lμmol/g) had a strong negative effect on iron solubility. When inositol hexa- and pentaphosphates of wheat bran and rye flour were completely hydrolyzed by activating endogenous phytase, iron solubility under simulated physiological conditions increased from 3 to 53% (wheat) and 5 to 21% (rye). Addition of wheat phytase to uncooked oatmeal increased iron solubility from 4 to 11 and in precooked to 18%, while endogenous phytase of uncooked oatmeal had less effect on phytate digestion and iron solubility.     

Processing Ingredients Affecting Oxidative and Textural Stability of Restructured Beef Roasts

Restructured beef roasts containing 0.3% sodium tripolyphosphate (STP) and 1% soy protein isolate (SPI); or STP only; or SPI only; or no STP or SPI were cooked at 70 or 100°C to an internal temperature of 65°C, then stored at 4°C for 0 and 3 days. In control roasts, the higher cooking temperature resulted in higher (p ≤ 0.05) TBA values. STP and SPI inhibited oxidation but the effect was not detected sensorially. Significant interactions (p ≤ 0.05) indicated that STP was more effective at higher cooking temperatures and SPI at lower temperatures. Total moisture of the cooked product was significantly greater with STP but no differences in juiciness and tenderness were detected sensorially.     

Application of rapid methods and ultrasound imaging in the assessment of the microbiological quality of aseptically packed starch soup

The application of rapid microbiological methods such as automated turbidometry and microcolony count using the direct epifluorescence technique (DEFT) was tested for the quality control of aseptically packed ultra-high temperature-treated starch-based soup. In addition, a non-destructive method using ultrasound imaging through the packages prior to the microbiological analysis was evaluated. The results showed that ultrasound could be a promising non-destructive testing method in quality control schemes for starch-based foods. Certain problems associated with calibration may arise in the application of turbidometry for heat-treated food material. Neither method studied in this work was sufficiently sensitive without a pre-incubation step.     

Two-phase flow in a proton exchange membrane electrolyzer visualized in situ by simultaneous neutron radiography and optical imaging

In proton exchange membrane (PEM) electrolyzers, oxygen evolution in the anode and flooding due to water cross-over in the cathode yields two distinct two-phase transport conditions which strongly affect the performance. Two-phase transport in an electrolyzer cell is visualized by simultaneous neutron radiography and optical imaging. Optical and neutron data are used in a complementary manner to aid in understanding the two-phase flow behavior. Two different patterns of gas-bubble evolution and departure are identified: periodic growth/removal of small bubbles vs. prolonged blockage by stagnant large bubbles. In addition, the bubble distribution across the active area is not uniform due to combined effects of buoyancy and proximity to the inlet. The effects of operating parameters such as current density, temperature and water flow rate on the two-phase distribution are investigated. Higher water accumulation is detected in the cathode chamber at higher current density, even though the cathode is purged with a high flow rate of N₂.     

Tri-reforming: A new biogas process for synthesis gas and hydrogen production

In this work biogas valorization – a renewable resource – for synthesis gas and hydrogen generation through dry reforming or tri-reforming (TR) is studied. Several Ni-based catalysts and a bimetallic Rh–Ni catalyst supported on magnesia or alumina modified with oxides like CeO₂ and ZrO₂ were used. For all the experiments, a synthetic biogas (molar composition: 60% CH₄ and 40% CO₂) was fed and the catalytic activities were measured in two different experimental facilities: a bench-scale fixed bed reactor system and a microreactor reaction system, at 1073 K and atmospheric pressure. Those catalysts which achieved high activity and stability in the fixed-bed reactor were impregnated in a microreactor to explore possible process intensification. For TR processes, different steam to carbon ratios, S/C, from 1.0 to 3.0, and O₂/CH₄ ratios of 0.25 and 0.50 were used. The high methane and carbon dioxide conversions reached in the fixed bed reactor were also achieved in the microreactor operating at much higher WHSV. In addition, process intensification improved catalysts stability. Physicochemical characterization of catalyst samples by ICP-OES, N₂ physisorption, H₂ chemisorption, TPR, SEM and XPS showed differences in chemical state, metal–support interactions, average crystallite sizes and redox properties of nickel and rhodium metal particles, indicating the importance of the morphological and surface properties of metal phases in driving the reforming activity.     

Photothermovoltaic effect in a pSi-n(Si2)1 − x − y (ZnSe) x (GaP) y (0 ≤ x ≤ 0.88, 0 ≤ y ≤ 0.09) structure

The results of creating a variband epitaxial (Si₂)_{1 ? x ? y} (ZnSe) _x (GaP) _y layer and observing the photothermovoltaic effect in a pSi-n(Si₂)_{1 ? x ? y} (ZnSe) _x (GaP) _y (0 ≤ x ≤ 0.88, 0 ≤ y ≤ 0.09) heterostructure heated by concentrated solar radiation are detailed. It is shown that the photothermal and thermal voltages in the heterostructure equal 5.8 and 1.2 mV at a temperature of 80°C. The observed relatively high photothermal voltage value is attributed to the possible extrinsic thermophotoelectric effect in the layer of diluted solid solution adjacent to the p-n junction.     

Diopside–Ba disilicate glass–ceramic sealants for SOFCs: Enhanced adhesion and thermal stability by Sr for Ca substitution

This article reports on the influence of strontium for calcium substitution in diopside–Ba disilicate glass–ceramics on stabilization thermal parameters and improvement adhesion to interconnect material of SOFCs. Sr replaced 10, 20, 30 and 40% of Ca in the Ca_0.9MgAl_0.1La_0.1Si_1.9O₆ component of the parent glass having the following composition, mol.%: 22.14 CaO, 24.60 MgO, 0.52 BaO, 1.23 Al₂O₃, 1.23 La₂O₃, 47.79 SiO₂, 1.69 B₂O₃, 0.79 NiO. ²⁹Si–MAS–NMR and ²⁷Al MAS–NMR spectra of the glasses revealed irrelevant chemical shifts for silicon and aluminum atoms upon changing the SrO content. T_g decreased and coefficient of thermal expansion (CTE) increased by Sr for Ca substitution in pyroxene glasses. Additionally SrO-containing glasses exhibited a viscosity of ∼10⁶ dPa s at 900 °C, which is suitable for joining of SOFC metallic/ceramic components by glass/glass–ceramic sealing upon stack hermetization. Glass–ceramics revealed long term (up to 1000 h) thermal stability at 900 °C and suitable CTE values (10.0–11.3) × 10⁻⁶ K⁻¹, high electrical resistivity, good adhesion and minimal reactivity with SOFC components.     

Review and Comparison of Nanofluid Thermal Conductivity and Heat Transfer Enhancements

This study provides a detailed literature review and an assessment of results of the research and development work forming the current status of nanofluid technology for heat transfer applications. Nanofluid technology is a relatively new field, and as such, the supporting studies are not extensive. Specifically, experimental results were reviewed in this study regarding the enhancement of the thermal conductivity and convective heat transfer of nanofluids relative to conventional heat transfer fluids, and assessments were made as to the state-of-the-art of verified parametric trends and magnitudes. Pertinent parameters of particle volume concentration, particle material, particle size, particle shape, base fluid material, temperature, additive, and acidity were considered individually, and experimental results from multiple research groups were used together when assessing results. To this end, published research results from many studies were recast using a common parameter to facilitate comparisons of data among research groups and to identify thermal property and heat transfer trends. The current state of knowledge is presented as well as areas where the data are presently inconclusive or conflicting. Heat transfer enhancement for available nanofluids is shown to be in the 15–40% range, with a few situations resulting in orders of magnitude enhancement.     

Multiscale Nonlocal Thermo-Elastic Analysis of Graphene Nanoribbons

This paper investigates the effect of interfacial thermal characteristics and nonlocal effects on the overall effective thermal property of graphene nanoribbons embedded in low-density polyethylene matrix. It is widely known that apart from the thermal conductivity, the effect of interfacial thermal resistance is the most important factor that determines the thermal efficiency of nanostructures. In this work, we develop nonlocal thermo-elastic properties coupled with a multiscale strategy by means of properties derived from atomistic simulations. Atomistic based thermal properties of graphene nanoribbons are estimated from molecular dynamics (MD) simulations and the effect of inter-tubular spacing on the interfacial thermal characteristics are also studied. The paper also discusses the effect of the nonlocal parameter on the thermal conduction of the composite system using the developed nonlocal thermo-elastic model.     

Cloning and disruption of the PpURA5 gene and construction of a set of integration vectors for the stable genetic modification of Pichia pastoris

A pair of degenerate primers was used for amplification and cloning of a DNA fragment containing parts of the P. pastoris URA5 and SEC65 genes. Using additional information from a partial genomic sequence of P. pastoris, we cloned and sequenced a 1.9 kb chromosomal fragment containing the complete orotate-phosphoribosyltransferase-encoding URA5 gene. A disruption cassette was constructed by replacing a small part of the open reading frame with a kanamycin-resistance gene. The P. pastoris wild-type strain NRRL Y-11430 was transformed with the disruption cassette and an ura5 auxotrophic strain was identified. To generate marker constructs that can be reused in successive transformations of a single strain, we constructed two lacZ-PpURA3-lacZ and lacZ-PpURA5-lacZ cassettes and used them to disrupt PpOCH1. The PpURA3 and PpURA5 genes in the disruptants were then successfully recycled by selecting for resistance to 5'-fluoro-orotic acid. We also assembled a set of modular plasmids that can be used for the stable genetic modification of P. pastoris via a double cross-over event. The sequence presented here has been submitted to the EMBL data library under Accession No. AY303544.