This article reports a study of the degradation of roasted sesame hulls cellulosic polysaccharides contribution to the Maillard and caramelization reaction. In the present study, cellulosic ...polysaccharides were extracted from sesame hulls before and after roasting at various temperatures (160, 180, 200, and 220 °C). The structural vari-ations of the cellulosic polysaccharides were elucidated by using the techniques: scanning electron microscope (SEM), high-performance anion-exchange chromatography, Fourier transform (FT-IR) spectrometer, carbon-13 nuclear magnetic resonance (CP/MAS 13C-NMR), and thermal gravimetric analysis. The pyrolysisgas chromatography-mass spectrometry (Py-GC/MS) characterized and verified the chemical composition obtained from the polysaccharide degradation during roasting. The sugar analysis results showed that galacturonic acid, xylose, and rhamnose were more easily degraded than arabinose, galactose, glucose, and mannose. The morphology of the cellulosic polysaccharides shows irregular dispersed globular fragments after roasting by SEM observation. FT-IR and CP/MAS 13C-NMR spectra indicated the crystalline structure and linkages of the cellulose did not break down in comparison to amorphous cellulose that partly degraded. Abundant acetic acid and 3-furaldehyde were among the polysaccharide degradation products identified by Py-GC/MS. These chemical compounds were likely the significant contributors to caramelization and the Maillard reaction in sesame seed roasting.
A considerable amount of slope stability analysis has been observed in jointed rock masses in which the GSI (Geological Strength Index) estimated at the outcropping level is considered input data to ...define the rock mass strength. However, this procedure is unsuitable when the rock outcrop scale and the slope scale are significantly different (e.g. open-pit slopes), resulting in an overestimated rock mass strength. For this reason, and in the absence of criteria to modify the GSI based on the scale effects, in this research, a new GSI version is proposed, called GSIe or “equivalent GSI”. To define an expression for obtaining the GSIe in terms of the rock mass properties, comparative stability analyses were conducted in a series of hypothetical slopes using two approaches: the first considers the rock mass as a discontinuous medium of rock blocks separated by discontinuities; the second considers the rock mass as an equivalent continuous medium characterized by an equivalent GSI. For the adequate equivalent GSI value, evaluated in each analyzed slope, the safety factor and the failure surface are similar in both approaches. In conformity with the results, a GSIe formulation in terms of the slope height, the spacing, the intact rock strength, the persistence, and the joint conditions has been proposed. Finally, the formulation was validated by applying it in five cases of mining slopes where the failure occurred.
Deep marine microorganisms survive under extreme ecological settings and harsh environmental conditions of low temperature, high salinity, and high atmospheric pressure making it significant of ...scientific interest. Southern Ocean (SO) is one such example of deep marine ecosystem and the microorganisms inhabiting in such hostile environment may produce different bioactive secondary metabolites. SO (Indian Sector) is relatively less documented in terms of microbial composition and community dynamics. The present study involves isolation of exopolysaccharides (EPSs) from three potent SO (Indian Sector) bacteria, optimization of the EPS production and partial characterization of them. Three different EPSs show varying structural conformation, that is from porous to strong flakes mimicking polymeric structure with C/N ratio ranging between 4 - 11. FTIR spectra have exhibited the presence of different active groups of carbohydrate moieties, water molecules and protein-associated amides. EPSs produced by marine microorganisms show high biotechnological promises such as drug carrier in pharmaceutical field, emulsifier and cryoprotectant in food-processing industry, detoxification of petrochemical oils and much more. The three bacterial isolates in this study showed potential of producing EPS biopolymer that can be further explored in terms of its proper biotechnological applications.
The microstructural alterations suffered during the process of drawing deformation and subsequent annealing of pearlitic steel wires, were evaluated by scanning electron microscopy and atomic force ...microscopy. The deformed material showed the curling structure in cross section while, in the longitudinal section, the lamellae was aligned with the drawing direction. The microstructural characterization of deformed samples also allowed observing an interlamellar spacing reduction and the intermediate lamellae alignment process. After the heat treatment at 1000ºC for 5 min the microstructure was restored, however, few recrystallized grains were observed. The recovery was the dominant phenomenon, due to factors associated with curling structure that inhibited recrystallization.
A major hurdle to realize molecular electronic devices (MEDs) is to make reliable electrical contacts to a single or a few molecules. Our nano-contact platform with a gap size of less than 25nm with ...resistances above 1000TΩ was built using combined techniques of photolithography, electron beam lithography and focused ion beam milling. In this study, we have used gold nanoparticles (AuNPs) to bridge the nanoelectrode gaps by dielectrophoretic trapping and thus obtain electrical contacts. The electrodes and/or the nanoparticles were functionalised with 1–2nm long alkane-thiol molecules so that the electronic structure of these molecules determines the properties of the electrical junction. Molecules were introduced both by functionalising the nanogap and the nanoparticles and the results of both functionalisation protocols are compared. Here, we show the nanogap–nanoparticle bridge set-up containing metal–molecule junctions that can be used as a base for the development of molecular electronics containing only a few molecules under ambient conditions. Current–voltage (I–V) characterization of alkanethiol/gold junction showed non-linear response where mean geometric resistance of four different junctions could be tuned from 20GΩ to 20TΩ. The results from the measurements on 1-alkanethiol in such devices is a first step to demonstrate that this platform has the potential to obtain stable electronic devices having relatively small numbers of molecules with reliable metal molecule junction by combing top-down and bottom-up approaches.
Quality control is of great importance in food industry, both for the evaluation of product characteristics and to avoid the occurrence of foreign bodies contamination in packaged items. With respect ...to the inspections against possible contaminants inside the product, different technologies are currently adopted along production chain lines. However, the number of accidents involving low density objects remains very large. To overcome this limitation, the use of electromagnetic technologies has been recently proposed. In this work, the synergic use of terahertz and microwaves technologies is proposed, so to provide high resolution images and in-depth inspections of different scenarios, including low density materials. A focus study on sugar samples is considered, reporting both its broadband characterization at microwaves and preliminary terahertz imaging to evaluate the integrity of the packaging. Ongoing research is devoted to the development and validation of a microwave device for monitoring food products along the production line.
Two thermostable xylanases, designated XynA and XynB, were purified to homogeneity from the culture supernatant of Paenibacillus sp. DG-22 by ion-exchange and gel-filtration chromatography. The ...molecular masses of xylanases A and B were 20 and 30 kDa, respectively, as determined by SDS-PAGE, and their isoelectric points were 9.1 and 8.9, respectively. Both enzymes had similar pH and temperature optima (pH 5.0-6.5 and 70℃), but their stability at various temperatures differed. Xylanase B was comparatively more stable than xylanase A at higher temperatures.
Spillover is a well-known phenomenon in heterogeneous catalysis and is involved in many important reactions. The establishment of the spillover concept opened up a new research field for an in-depth ...understanding of the dynamic behavior of migrated species on a catalyst surface. However, a comprehensive understanding of spillover remains lacking. In recent years, the development of advanced characterization techniques in combination with well-controlled synthesis methodologies has provided us with increasing worthwhile information about spillover. This Review mainly describes recent progress on the characterization and mechanism of hydrogen spillover and how to effectively utilize the spillover effect for enhanced catalytic performance. Additionally, the challenges remaining in this research area are discussed, and possible research directions for the future are proposed.
A simple route to achieve covalently-grafted polyaniline (PANI)/graphene oxide (GO) nanocomposites has been developed. The synthesized composites showed a uniform hierarchical morphology of the PANI ...thin film and short rod-like nanostructures that had densely grown on the GO sheets, in contrast to the nonuniform morphology of noncovalently-grafted PANI/GO. Compared to pure PANI and noncovalently-grafted PANI/GO composites, the covalently-grafted PANI/GO composites possessed a much larger specific surface area and pore volume, which increased the accessible surface area for the redox reaction and allowed faster ion diffusion. This unique hierarchical morphology maximized the synergistic effect between PANI and GO, resulting in excellent electrochemical performance (capacitance 442F/g of PANI/GO (6:1) vs. 226F/g of pure PANI) and improved cycling stability (83% @ 2000 cycles of PANI/GO (6:1) vs. 54.3% @ 1000 cycles of pure PANI). The enhanced electrochemical performance demonstrates the advantage of the PANI/GO composites prepared via this covalent grafting method.
•Fully unlocking lignin’s potential will promote the entire biorefinery process.•Methods of lignin extraction, characterization, and conversion are reviewed.•Challenges on lignin valorization are ...analyzed.•Opportunities and strategies to improve lignin utilization are given.
The exploration of effective approaches for the valorization of lignin to valuable products attracts broad interests of a growing scientific community. By fully unlocking the potential of the world’s most abundant resource of bio-aromatics, it could improve the profitability and carbon efficiency of the entire biorefinery process, thus accelerate the replacement of fossil resources with bioresources in our society. The successful realization of this goal depends on the development of technologies to overcome the following challenges, including: 1) efficient biomass pretreatment and lignin separation technologies that overcomes its diverse structure and complex chemistry challenges to obtain high purity lignin; 2) advanced chemical analysis for precise quantitative characterization of the lignin in chemical transformation processes; 3) novel approaches for conversion of biomass-derived lignin to valuable products. This review summarizes the latest cutting-edge innovations of lignin chemical valorization with the focus on the aforementioned three key aspects.
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