The application of microwave heating to the synthesis of 6-amino-6-deoxycellulose

Microwave heating was applied to the reactions involved in the synthesis of 6-amino-6-deoxycellulose, 4. These included, cellulose solubilization, bromination at C-6, displacement of bromine with azide ion, and reduction of the azido group to an amino group. Compared to conventional heating, this approach had the advantages of shortening reaction times and retaining the degree of polymerization of 4.     

Millimeter‐Wave Heating in In Vitro Studies: Effect of Convection in Continuous and Pulse‐Modulated Regimes

Shallow penetration of millimeter waves (MMW) and non‐uniform illumination in in vitro experiments result in a non‐uniform distribution of the specific absorption rate (SAR). These SAR gradients trigger convective currents in liquids affecting transient and steady‐state temperature distributions. We analyzed the effect of convection on temperature dynamics during MMW exposure in continuous‐wave (CW) and pulsed‐wave (PW) amplitude‐modulated regimes using micro‐thermocouples. Temperature rise kinetics are characterized by the occurrence of a temperature peak that shifts to shorter times as the SAR of the MMW exposure increases and precedes initiation of convection in bulk. Furthermore, we demonstrate that the liquid volume impacts convection. Increasing the volume results in earlier triggering of convection and in a greater cooling rate after the end of the exposure. In PW regimes, convection strongly depends on the pulse duration that affects the heat pulse amplitude and cooling rate. The latter results in a change of the average temperature in PW regime. Bioelectromagnetics. 2019;40:553–568. © 2019 Bioelectromagnetics Society.     

Transformation of the dermal collagen framework under laser heating

The aim of this study was to compare between the changes undergone by the dermal collagen framework when heated by IR laser radiation and by traditional means and to reveal the specific features of the dermal matrix modification under moderate IR laser irradiation. Rabbit skin specimens were heated to 50°C, 55°C, 60°C and 65°C in a calorimeter furnace and with a 1.68‐μm fiber Raman laser. The proportion of the degraded collagen macromolecules was determined by differential scanning calorimetry. Changes in the architectonics of the collagen framework were revealed by using standard, phase‐contrast, polarization optical and scanning electron microscopy techniques. The collagen denaturation and dermal matrix amorphization temperature in the case of laser heating proved to be lower by 10°C than that for heating in the calorimeter furnace. The IR laser treatment of the skin was found to cause a specific low‐temperature (45°C‐50°C) transformation of its collagen framework, with some collagen macromolecules remaining intact. The transformation reduces to the splitting of collagen bundles and distortion of the course of collagen fibers. The denaturation of collagen macromolecules in the case of traditional heating takes its course in a threshold manner, so that their pre‐denaturation morphological changes are insignificant.     

Characterization and bioleaching of nickel laterite ore using Bacillus subtilis strain

There are two principal types of nickel (Ni) deposits: sulfide and laterite ores. Interest in low-grade Ni-laterite ores has increased in recent years as high-grade Ni-sulfide deposits are being quickly depleted. However, processing of Ni laterites has proven technically difficult and costly, and the development of alternative low-cost biotechnologies for Ni solubilization has been encouraged. In this context, by the first time, a sample of Brazilian Ni-laterite ore was analyzed mineralogically and subjected to bioleaching tests using a heterotrophic Bacillus subtilis strain. SEM-analysis indicated that the primary Ni carrier mineral is goethite. Chemical analysis of different grain size fractions indicated a homogeneous distribution of Ni. XRF-analysis showed that the ore consists mainly in lizardite (32.6% MgO) and contains1.0% NiO (0.85% Ni). Bioleaching batch experiments demonstrated that about 8.1% Ni (0.7 mg Ni/g ore) were solubilized by the B. subtilis after 7 days. Application of microwave heating as a Ni-laterite pretreatment was also tested. This pretreatment increased the bioextraction of Ni from 8% to 26% (2.3 mg Ni g⁻¹ ore).     

Bergmann's Rule rules body size in an ectotherm: heat conservation in a lizard along a 2200‐metre elevational gradient

Bergmann's Rule predicts larger body sizes in colder habitats, increasing organisms' ability to conserve heat. Originally formulated for endotherms, it is controversial whether Bergmann's Rule may be applicable to ectotherms, given that larger ectotherms show diminished capacity for heating up. We predict that Bergmann's Rule will be applicable to ectotherms when the benefits of a higher conservation of heat due to a larger body size overcompensate for decreased capacity to heating up. We test this hypothesis in the lizard Psammodromus algirus, which shows increased body size with elevation in Sierra Nevada (SE Spain). We measured heating and cooling rates of lizards from different elevations (from 300 to 2500 m above sea level) under controlled conditions. We found no significant differences in the heating rate along an elevational gradient. However, the cooling rate diminished with elevation and body size: highland lizards, with larger masses, have a higher thermal inertia for cooling, which allows them to maintain heat for more time and keep a high body temperature despite the lower thermal availability. Consequently, the net gaining of heat increased with elevation and body size. This study highlights that the heat conservation mechanism for explaining Bergmann's Rule works and is applicable to ectotherms, depending on the thermal benefits and costs associated with larger body sizes.     

Functional group and fertilization affect the composition and bioenergy yields of prairie plants

Prairies used for bioenergy production have potential to generate marketable products while enhancing environmental quality, but little is known about how prairie species composition and nutrient management affect the suitability of prairie biomass for bioenergy production. We determined how functional‐group identity and nitrogen fertilization affected feedstock characteristics and estimated bioenergy yields of prairie plants, and compared those prairie characteristics to that of corn stover. We tested our objectives with a field experiment that was set up as a 5 × 2 incomplete factorial design with C₃ grasses, C₄ grasses, legumes, and multi‐functional‐group mixtures grown with and without nitrogen fertilizer; a fertilized corn treatment was also included. We determined cell wall, hemicellulose, cellulose, and ash concentrations; ethanol conversion ratios; gross caloric ratios; aboveground biomass production; ethanol yields; and energy yields for all treatments. Prairie functional‐group identity affected the biomass feedstock characteristics, whereas nitrogen fertilization did not. Functional group and fertilization had a strong effect on aboveground biomass production, which was the major predictor of ethanol and energy yields. C₄ grasses, especially when fertilized, had among the most favorable bioenergy characteristics with high estimated ethanol conversion ratios and nongrain biomass production, relatively high gross caloric ratios, and low ash concentrations. The bioenergy characteristics of corn stover, from an annual C₄ grass, were similar to those of the biomass of perennial C₄ grasses. Both functional‐group composition and nitrogen fertility management were found to be important in optimizing bioenergy production from prairies.     

Development of a radio frequency heating system for sterilization of vacuum-packed fish in water

We developed equipment that quickly and uniformly heats packed whole fish in circulating tap water using radio frequency (RF) heating. Four vacuumed plastic-packed Pacific sauries in tap water were set in a radial arrangement between coaxial cylindrical electrodes in a closed vessel. For sterilization testing, Bacillus subtilis spores added in the center of the sauries were counted after treatment. For quality assurance, meat color and backbone hardness were measured after treatment. The temperature at the center of the sauries was increased up to 130 °C for 19 min using 9 kW RF heating, and up to 119 °C for 45 min using conventional heating (CH) at 120 °C. B. subtilis spores were decreased by five logarithmic orders using RF heating and by four logarithmic orders using CH. The RF-treated meat was brighter than the CH-treated meat, and the RF-treated backbone was softer than CH-treated one.     

Synchrotron-Based FTIR Spectromicroscopy: Cytotoxicity and Heating Considerations

Synchrotron radiation-based Fouriertransform infrared (SR-FTIR)spectromicroscopy is a newly emergingbioanalytical and imaging tool. This uniquetechnique provides mid-infrared (IR)spectra, hence chemical information, withhigh signal-to-noise at spatial resolutionsas fine as 3 to 10 microns. Thus it enablesresearchers to locate, identify, and trackspecific chemical events within anindividual living mammalian cell. Mid-IRphotons are too low in energy (0.05–0.5eV) to either break bonds or to causeionization. In this review, we show thatthe synchrotron IR beam has no detectableeffects on the short- and long-termviability, reproductive integrity,cell-cycle progression, and mitochondrialmetabolism in living human cells, andproduces only minimal sample heating (<0.5°C). These studies haveestablished an important foundation forSR-FTIR spectromicroscopy in biological andbiomedical research.