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关键词： Malic acid   Food processing   Food preservative   Metal chelating   Antibacterial agent   Pectin gels  

摘要： Malic acid, a carboxylic acid most found in fruits, is a smooth taste substance used as flavoring and preservative agent in foods, although not as used as citric acid. There are no studies focusing in quantitative results or investigations on its physicochemical properties, useful to the food industry, or even the confirmation of its calcium chelating, buffer texturizer and antioxidant alleged properties. Thus, the aim of this work was the assessment of most physicochemical properties of malic acid, solid and in solution, that could be useful to the food industry understand its real potential. The following analyses were carried out: melting point;structure (NMR, XRD, FTIR and SEM/EDS);TGA/DTG;solubility, hygroscopicity;antioxidant activity, iron chelating and antibacterial activities and stability of pectin gels. The melting temperature found was 129.71 degrees C. TGA/DTG exhibited first loss of mass around 140 degrees C. In the temperature range of 10 to 55 degrees C, it exhibited a high solubility in water, from 48.12 to 61.49 (100w), respectively. The tested bacteria, related to food spoilage, were inhibited by DL-malic acid 10% or higher. Chelating and antioxidant activities showed expressive results even in 1% solution. Pectin gels with malic acid had stronger structure and less syneresis than citric acid gels. In addition, calcium chelating, buffer texturizer and antioxidant properties were confirmed. Thus, malic acid has potential to be applied in a wide variety of food products as fortified beverages, frozen and refrigerated items, oils, pectin gels, hard and soft candies, and biofilms, due to all the characteristics quantified. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.

关键词： Starch   Functional groups   Impedance spectroscopy   Anode materials  

摘要： Starch is a modern and prospective biodegradable material, which could improve lithium-ion batteries by making them safer and thus increasing the energy density and capacity of the cells. The main aim of this study was to research the influence of the physical and chemical properties of different botanical origin starches on their electrochemical properties. The investigation was carried out by examining the colloid stability of starches in water solution at room temperature, and the size of particles, which gave really good stability results. Moreover, the vibrations and the functional groups structure were described by Fourier Transform Infrared Spectroscopy (FTIR). The surface properties were characterized by determining the specific surface area, pore diameter and volume diameter. The structures of the granules were determined by scanning electron microscope (SEM) measurement. The results of the electrochemical investigations showed good cyclic reversibility and stability. The research was aimed at improving and modifying current lithium-ion cells using biodegradable material as an active anode material, which is connected with the currently well-known "Green Chemistry". (C) 2020 Elsevier B.V. All rights reserved.

关键词： polysaccharide   galactomannan   enzymatic hydrolysis   alpha-galactosidase   double-stranded galactomannan   galactose   mannose  

摘要： The aim of the study is isolation of galactomannan from plant materials and investigation of their physical and chemical properties. Polysaccharides generally consisting of galactomannan were isolated and purified from galactomannans from the seeds of the plants Sophora japonica and Gleditsia triacanthos by cold and hot extraction methods. Galactose and mannose contents of the galactomannans isolated were quantitatively characterized and physical and chemical properties of the polysaccharides were studied. In addition, polysaccharides isolated were enzymatic hydrolyzed and changes in the monosaccharide composition in the hydrolysis process were studied. The characteristic viscosities of the initial and hydrolyzed galactomannans were 4.85-3.80 dL/g, respectively. Molecular weights of the galactomannans, after treatment with the enzyme, changed in a range of 55 600-26 200 Da. Studies with H-1 and C-13 NMR spectroscopy methods showed decreases in galactoside content of the hydrolyzed galactomannans, indicating the primary course of hydrolysis occurs by the side chain of the macromolecule. Increase in duration of enzymatic hydrolysis more than 24 h led to the formation of poly-mannans with a minor content of galactose units. The data can serve to improve isolation and preparation of galactomannan based materials for biomedical purposes.

关键词： Ceramics   Nitrogen addition   Thermal analysis   Cyclic voltammetry  

摘要： Nitrogen containing lanthanum manganite perovskite material has been successfully synthesized through sol-gel method using urea (CH4N2O) as a nitrogen source. The obtained powders were followed thermal treatment at low temperature. In order to achieve a comparative study on the obtained materials, three concentrations of urea were used (0.05;0.1 and 0.15%). The characteristic of the materials were examined by differential thermal analysis (TG/DTA/HF), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning/transmission electron microscope (SEM/TEM), energy-dispersive X-ray spectroscopy (EDX) and electrochemical measurements were made. The XRD patterns show that all analyzed sample are well crystallized and present a perovskite single phase with the cubic structure, space group: Pm-3m, with the average size of crystallites around 30 nm. All the N-doped LaMnO3 perovskites exhibit remarkable electrocatalytic effect on the redox reaction of potassium ferricyanide improving redox peak current. (C) 2020 Elsevier B.V. All rights reserved.

关键词： airborne thermal imaging   coastal hydrology   groundwater   groundwater discharge to lagoons   groundwater-surface water interaction   lagoon   radon   spatial distribution of groundwater discharge  

摘要： Coastal lagoons are significant wetland environments found on coastlines throughout the world. Groundwater seepage may be a key component of lagoon water balances, though only a few studies have investigated large (>100 km(2)) coastal lagoons. In this study, we combined airborne thermal infrared imagery with continuous measurements of radon (Rn-222-a natural groundwater tracer), conductivity, water temperature and dissolved oxygen to map groundwater seepage to a large coastal lagoon in New Zealand. We found evidence of seepage along the margins of the lagoon but not away from the margins. Our findings confirmed previously known seepage zones and identified new potential locations of groundwater inflow. Both point source and diffuse seepage occurred on the western and northwestern margins of the lagoon and parallel to the barrier between the lagoon and sea. These observations imply geologic controls on seepage. The combination of remote sensing and in-situ radon measurements allowed us to effectively map groundwater discharge areas across the entire lagoon. Combined, broad-scale qualitative methods built confidence in our interpretation of groundwater discharge locations in a large, dynamic coastal lagoon.

关键词： Selenium nanoparticle   Chitosan   Molecular weight   Physicochemical property   Se release   Antioxidant capacity   Antibacterial activity  

摘要： Selenium nanoparticles (Se(0)NPs) have been well-characterized;however, whether processing affects their physicochemical and functional properties remains unknown. Here, chitosan (low and high molecular weight;CS(L) and CS(H), respectively) was used to stabilize Se(0)NPs, and the effects of heating (37 degrees C, 70 degrees C, and 95 degrees C), freeze-drying-rehydration, and freeze-thawing on CS-Se(0)NPs physicochemical stability, Se release, antioxidant capacity, and antibacterial activity were evaluated. The results demonstrated that all treatments could cause CSSe(0)NPs aggregation and Se release to varying degrees. Aggregation of CS-Se(0)NPs decreased their antibacterial activity, while Se release increased their antioxidant capacity with negligible effects on antibacterial activities. None of the CS-Se(0)NPs could tolerate freeze-thawing. CS(H)-Se(0)NPs exhibited better rehydration and heating stability than CS(L)-Se(0)NPs, although "rod-like" triclinic crystalline Se in CS(H)-Se(0)NPs, produced by 95 degrees C heating, decreased both antioxidant and antibacterial activities. Thus, these results provide a theoretical basis for the development and suitable application of CS-Se(0)NPs.

关键词： Boron particles   Ni nanoparticles   Electroless deposition   Rinsing   Drying  

摘要： Ni nanoparticles were coated on irregularly shaped micron sized boron particles by facile electroless Ni-deposition method. Four kinds of Ni-coated boron particles were prepared using four different simple paths during the electroless deposition process: no rinsing and no drying (Path A), only drying (Path B), both rinsing and drying (Path C), and only rinsing (Path D). Surface morphology confirmed the Ni-nanoparticles coating on the surface of boron particles. The size of the Ni nanoparticles varied between 10 and 120 nm with respect to the chosen paths used for preparation. The Ni nanoparticle's size was also studied using TEM and found to be consistent with the surface morphology results. XRD measurement of the Ni-coated boron particles showed the formation of crystalline Ni nanoparticles. EDAX and XPS results showed the presence of the primary B and Ni elements in the obtained samples. Thermogravimetric analysis conducted in air atmosphere found the boron particles had enhanced oxidation resistance after the coating of Ni nanoparticles. The Ni-coated boron particles showed a shift in exothermic peak to a lower temperature and higher heat evolution than the pure boron, recommending the use of Ni-coated boron particles in solid fuel in missile/rocket engines, and high temperature applications. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

关键词： Oryza sativa L.   ALK gene   gelatinization temperature   amylopectin   starch fine structure   crystallinity  

摘要： The gelatinization temperature (GT) of endosperm starch influences rice eating and the cooking quality (ECQ). ALK encoding soluble starch synthase IIa (SSIIa) is the major gene determining grain GT in rice. Herein, we identified a spontaneous ALK mutant named ALK(d), which resulted from a G/T single-nucleotide polymorphism (SNP) in exon 1 of the ALK(c) allele from the high-GT indica rice cultivar. Compared with grains from the ALK(c) near-isogenic line (NIL), NIL(ALK(d)) grains exhibited a high GT (2.3 degrees C) and improved retrogradation properties. The NIL(ALKa) grain starch contained an increased proportion of amylopectin intermediate chains (DP 13-24) at the expense of short chains (DP < 12), resulting in enhancements in both the crystallinity and the lamellar peak intensity compared with low-GT rice grains. Moreover, both NIL(ALK(d)) and NIL(ALK) grains also featured a significantly lower apparent amylose content (AAC), harder gel consistency (GC), higher pasting curve, and poorer taste values in comparison to Nip(ALK(d)) grains. Taken together, this work provides novel insights underlying the allelic variation of the ALK gene in rice.

关键词： Alendronate   cytotoxicity   platinum   polyamidoamine   polymer-drug conjugates   procaine  

摘要： Platinum-based drugs are potent anticancer drugs and are effective for the treatment of various cancers. However, they are limited pharmacologically due to toxic side effects, drug resistance and poor water solubility. In order to overcome these limitations, platinum was incorporated onto polyamidoamine carriers together with alendronate and procaine hydrochloride to form a series of conjugates. Cytotoxicity was assessed using the sulforhodamine B assay on MCF-7, MDA-MB-231 and ***926 cell lines. The polymer-drug conjugates showed cytotoxicity which was selective to the cancer cell lines. The free drugs decreased cell density in all cell lines and were nonspecific. These findings indicate that the incorporation of bioactive agents onto polymers can overcome cytotoxicity associated with the drugs. The selective inhibitory effects of the conjugates towards the cancer cell lines suggest that these conjugates are potential therapeutics for combination therapy.

关键词： Hydrogen bonds  

摘要： Although molecular recognition at the air-water interface has been researched for over 30 years, investigations on its fundamental aspects are still active research targets in current science. In this perspective article, developments and future possibilities of molecular recognition at the air-water interface from pioneering research efforts to current examples are overviewed especially from the physico-chemical viewpoints. Significant enhancements of binding constants for molecular recognition are actually observed at the air-water interface although molecular interactions such as hydrogen bonding are usually suppressed in aqueous media. Recent advanced analytical strategies for direct characterization of interfacial molecules also confirmed the promoted formation of hydrogen bonding at the air-water interfaces. Traditional quantum chemical approaches indicate that modulation of electronic distributions through effects from low-dielectric phases would be the origin of enhanced molecular interactions at the air-water interface. Further theoretical considerations suggest that unusual potential changes for enhanced molecular interactions are available only within a limited range from the interface. These results would be related with molecular recognition in biomolecular systems that is similarly supported by promoted molecular interactions in interfacial environments such as cell membranes, surfaces of protein interiors, and macromolecular interfaces.