Combined Thermal Treatment Research Articles

Future Cereal Starch Bioengineering: Cereal Ancestors Encounter Gene Technology and Designer Enzymes

ABSTRACTThe importance of cereal starch production worldwide cannot be overrated. However, the qualities and resulting values of existing raw and processed starch do not fully meet future demands for environmentally friendly production of renewable, advanced biomaterials, functional foods, and biomedical additives. New approaches for starch bioengineering are needed. In this review, we discuss cereal starch from a combined universal bioresource point of view. The combination of new biotechniques and clean technology methods can be implemented to replace, for example, chemical modification. The recently released cereal genomes and the exploding advancement in whole genome sequencing now pave the road for identifying new genes to be exploited to generate a multitude of completely new starch functionalities directly in the cereal grain, converting cereal crops to production plants. Newly released genome data from cereal ancestors can potentially allow for the reintroduction of cereal traits including, for example, health‐promoting carbohydrates that may have been lost during domestication. Raw materials produced in this manner can be processed by clean enzyme‐assisted techniques or thermal treatment in combination to further functionalize or stabilize the starch polymers. Importantly, such products can be multifunctional in the sense of combined food/material or food/pharma purposes, for example, edible plastics, shape memory materials, and cycloamylose carriers and stabilizers for diverse bioactives.

The effects of a combined thermal treatment of substrate heating and post‐annealing on the microstructure of InGaZnO films and the device performance of their thin film transistors

This study examined the possibility of engineering the microstructure of InGaZnO films and enhancing the device performance of their thin film transistors by combining the thermal treatments of substrate heating and post‐annealing. Microstructure characterization using high‐resolution transmission electron microscopy and energy‐filtered selected area electron diffraction helped us to unravel a systematic improvement in atomic order induced by substrate heating. Hall measurement analysis confirmed that the electrical properties (carrier concentration and electron mobility) varied very sensitively with the thermal treatments. The combined thermal treatments were found to effectively enhance the overall device performance of the transistors, and the sample deposited at 200 °C and post‐annealed at 400 °C showed the best transistor characteristics with a saturation mobility (μsat) of nearly 26 cm2/V s. Copyright © 2012 John Wiley & Sons, Ltd.

Magnetic clusters in amorphous metal alloys

The effect of thermal treatment in combination with an external magnetic field and/or elastic stress on the magnetic characteristics of amorphous metal alloys of the 2NSR type is studied. The complex behavior of the magnetization and coercivity values in dependence on the length of annealing at temperatures below crystallization is described. It is assumed that the observed changes in the macroscopic magnetic characteristics are associated with the formation of clusters with different degrees of exchange interaction.

Stretching-induced deformation of polyacrylonitrile chains both in quasicrystals and in amorphous regions during the in situ thermal modification of fibers prior to oxidative stabilization

In situ thermal stretching to modify the conformation of polyacrylonitrile (PAN) chains in quasicrystals and amorphous regions is carried out on PAN copolymer fibers prior to oxidative stabilization. Meanwhile, a model to evaluate the deformation of PAN quasicrystals and amorphous regions is proposed, in which deformation behavior (orientation or extension) and type (elastic or plastic) in the two regions are analyzed. PAN chains exhibit various deformations as a consequence of combined thermal treatment and mechanical stretching. The orientation of PAN chains occurs prior to their extension when the stretching ratio is under 1.06, however, no significant orientation but extension is observed when the deformation ratio ranges from 1.08 to 1.16. As the stretching ratio increases, elastic-dominated orientation of PAN chains is stronger in quasicrystals before 1.03 and is prominent in amorphous regions between 1.04 and 1.08. The mechanical properties of the resulting carbon fibers strongly depend on the orientation degree of PAN chains in amorphous regions.

Simultaneous Plasma and Thermal Treatments of ITO Surfaces for Organic Solar Cells

Organic solar cells' power conversion efficiency was improved by combined thermal and CF4 plasma surface treatments of indium tin oxide (ITO). This was further enhanced by adding O2 to the CF4 plasma, which increased atomic fluorine concentration. Organic solar cells were produced with layered structures of ITO, spin-cast thin film of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) mixture (100 nm), and Al (100 nm) as top electrode. While CF4 plasma surface treatment alone significantly improved power conversion efficiency (PCE), from 0.34% to 1.99%, further enhancements occurred with the combined thermal treatment, up to 2.24%. 20% O2 addition to the CF4 plasma resulted in greatest improvement (up to 2.34%) due to optimized surface fluorination. Measured work functions of surface treated ITO increased from 4.80 to 5.17 eV with the plasma and thermal treatments. Such treatments reduce the energy barrier for hole injection at the ITO surface by increasing ITO's work function.

Effect of a New Thermal Treatment in Combination with Saprobic Fungal Incubation on the Phytotoxicity Level of Alperujo

Byproducts generated from food industries, such as olive oil mills, have been studied to decrease harmful pollution and their environmental consequences. In this work, a new thermal pretreatment and saprobic fungal incubation to detoxify alperujo (two-phase olive mill waste) have been evaluated in view of its use as fertilizer in agriculture. The sequential use of both methods simplifies the thermal conditions and incubation times of the fungal treatment. Optimization of the thermal treatment from 150 to 170 °C for 45 and 15 min, respectively, reduced the incubation time with Coriolpsis rigida from 20 to 10 weeks needed to reduce phytotoxic effects on tomato plants. Therefore, the combination of thermal and biological treatments will allow the development of the potential benefits of alperujo to improve nutrients in agricultural soil.

Influence of Thermal Treatment of Ni-P Melt on Structure of Amorphous Alloys

The structure of amorphous metallic glasses prepared by rapid melt quenching on the rotating drum is sensitive to processing parameters. Many physical properties of amorphous metallic alloys (magnetic, electric and mechanical) are also dependent on the structure. Morphology of fracture surfaces for ribbons of amorphous alloy Ni81P19 prepared from differently thermally treated melts was observed. The highest fracture stress was observed for the ribbon prepared from the melt subjected to the combined thermal treatment. The side of the ribbon which is in contact with rotating wheel during the quenching shows to be partially brittle. Initiations of a chevron type fracture are localized near this surface. The opposite side of the ribbon always failed through meniscus instability mechanism. This difference is considered to be caused by the changes in the melt atomic structure under heating above the critical temperature and after quenching it is preserved in amorphous alloys.

Crystallization of Monodisperse Lead Zirconate Titanate Nanoparticles Produced by Laser Ablation

Monodisperse lead zirconate titanate (PZT) nanoparticles with diameters of 9 nm were produced by laser ablation followed by a gas-phase thermal treatment in combination with a size-classification technique using a very low-pressure differential mobility analyzer. The particles prior to the thermal treatment are amorphous. When the laser power density for ablation increases from 0.5 GW/cm2 to 12 GW/cm2, the production yield of the particles increases regardless of the laser photon energy. When the laser photon energy is 3.5 eV, the nanoparticles generated with laser power densities as high as 7 GW/cm2 are crystallized to perovskite by thermal treatment at 900°C, while those generated with even higher power densities become pyrochlore. In contrast, when the laser photon energy is 2.3 eV, perovskite nanoparticles are obtained only at a power density of 0.5 GW/cm2. These results reveal that the crystalline structure of PZT nanoparticles can be adjusted to perovskite or pyrochlore by changing thermal treatment temperature, laser power density, and photon energy. Furthermore, X-ray photoelectron spectroscopy indicates that the crystallization to pyrochlore is caused by lead deficiency.

An efficient method for blocking the 1st mitotic cleavage of fish zygote using combined thermal treatment, exemplified by mud loach ( Misgurnus mizolepis)

Blocking the first mitotic cleavage of the zygote is a key tool for chromosome-set manipulations in fish. We developed an improved method for inducing tetraploidy by blocking the mitosis with a combination of heat shock at 40.5 °C for 1, 2, or 3 min followed by cold shock at 1.5 °C for 30, 45, or 60 min. When applied during the first cleavage metaphase of mud loach ( Misgurnus mizolepis) zygotes, the optimal combination was heat for 2 min followed by cold for 45 min. At 1 month, the frequency of 4N survivors and the yield from total eggs fertilized was 55.7 and 14.4%, respectively, compared to heat shock alone with 20.0% efficiency and 3.6% yield. The effectiveness of the procedure was confirmed by diploid mitotic gynogenesis using transgenic markers. The overall yield of homozygous diploids, 34.0%, was better than that for single heat shock, 17.3%. The tetraploids and homozygous diploids had higher early mortality than normal diploid controls. However, at 1 month, the viability of the tetraploids was the same as normal diploids. For gynogenetic diploids, the survival was similar to normal diploids after 3 months. The high efficiency of this new protocol extends the opportunity to study polyploidy in basic and applied research.

Model studies on the stability of folic acid and 5-methyltetrahydrofolic acid degradation during thermal treatment in combination with high hydrostatic pressure.

Stability of folic acid and 5-methyltetrahydrofolic acid in phosphate buffer (0.2 M; pH 7) toward thermal (above 65 degrees C) and combined high pressure (up to 800 MPa)/thermal (20 up to 65 degrees C) treatments was studied on a kinetic basis. Residual folate concentration after thermal and high pressure/thermal treatments was measured using reverse phase liquid chromatography. The degradation of both folates followed first-order reaction kinetics. At ambient pressure, the estimated Arrhenius activation energy (E(a)) values of folic acid and 5-methyltetrahydrofolic acid thermal degradation were 51.66 and 79.98 kJ mol(-1), respectively. It was noticed that the stability of folic acid toward thermal and combined high pressure thermal treatments was much higher than 5-methyltetrahydrofolic acid. High-pressure treatments at room temperature or higher (up to 60 degrees C) had no or little effect on folic acid. In the whole P/T area studied, the rate constant of 5-methyltetrahydrofolic acid degradation was enhanced by increasing pressure, and a remarkable synergistic effect of pressure and temperature on 5-methyltetrahydrofolic acid degradation occurred at temperatures above 40 degrees C. A model to describe the combined pressure and temperature effect on the 5-methyltetrahydrofolic acid degradation rate constant is presented.

Thermal treatment and foaming of chars obtained from almond shells: kinetic study

The influence of a combined thermal treatment on the density of chars obtained from almond shells has been investigated. The thermal treatment involves two steps at different heating rates: the first one up to temperatures of 225–400°C; and the second one up to 850°C. Thermogravimetric experiments have been carried out with the intermediate chars obtained after treatment revealing the evolution of the different fractions of the almond shells (i.e. hemicellulose, cellulose and lignin), and their influence on the final density of the chars. An intermediate treatment, where the gases evolved from the last remaining fractions of the cellulose coincide with the char in a fluid or soft state, is required to foam the particles. A kinetic model has been applied to quantify, with excellent results, the evolution of the different fractions.

Manufacturing of $\alpha$-lactalbumin-enriched whey systems by selective thermal treatment in combination with membrane processes

Till now, industrial fractionation and isolation processes for whey proteins have mainly been based on chemical process steps combined with membrane techniques. Actually, the reaction kinetics of thermal denaturation of α-lactalbumin and β-lactoglobulin allow to compute the remain- ing portions of native whey proteins in dependence of the selected temperature-time conditions. In the temperature range of 85-95 °C and corresponding holding times, the differences in reaction rates for both whey protein fractions are highest i.e. only moderate denaturation for α-lactalbumin but extensive denaturation for β-lactoglobulin. After such thermal treatment the ratio of native α-lactal- bumin to native β-lactoglobulin may increase from 0.3 (raw milk) to approximately 4. An effective separation of aggregated (denatured) whey proteins from soluble whey proteins is achieved by means of microfiltration (ceramic membranes / 0.1 μm).

Influence of thermal treatment regime on the density and reactivity of activated carbons from almond shells

A study of the influence of two successive thermal treatments, at low (3–4°C min −1) and high (ca. 3000°C min −1) heating rate, on the properties and reactivity of chars obtained from almond shells was carried out. The combined thermal treatment consisted of a first stage at intermediate temperatures from 275 to 400°C at the low heating rate, followed by a second stage at the high rate, up to 850°C. All the samples obtained under these conditions (except the sample obtained at an intermediate temperature of 400°C) yielded a density much lower than that corresponding to a single thermal treatment up to 850°C at both heating rates. The sample obtained at 400°C behaved in a very interesting manner since its density was the highest obtained. A correlation has been obtained between the high reactivity of the samples obtained by a single treatment at high heating rate, and the Ca content and dispersion. The adsorption properties of the activated carbons obtained at approximately 50% burn-off were very similar regardless of the reactivity and the porous structure of the precursor chars.