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关键词： Chitosan   Degree of deacetylation   Genipin   Biocatalyst   beta-D-galactosidase  

摘要： The effect of the degree of deacetylation (DD) on the characteristics of the support matrix formed through chitosan (CH) and genipin (GE) crosslinking was investigated by using CH with DD of 83, 94 and 96%. The rheological properties of CH dispersions were determined in order to study the influence of DD on the CH viscosity, gel network structures and gelation temperature (Tgel). The CH exhibited the shear-thinning behavior of pseudoplastic fluids. Tgel decreased with the increase of DD and the sol-gel transition temperature of CH-83, CH-94 and CH-96 were 75, 30 and 25 degrees C, respectively. The magnitude of viscous modulus (G) was higher than the elastic modulus (G'), revealing the formation of a weak gel structure. The CH dispersions have been used in the preparation of beads and then crosslinked with GE to form support matrices. Besides, to verify how it influences in a practical application, an enzymatic immobilization was carried out using a beta-D-galactosidase (BG) as a model, which could be advantageously employed to promote hydrolysis of lactose. Scanning Electron Microscope images showed biocatalysts with multiple porous compartments. Fourier Transform Infrared Spectroscopy (FTIR) analyses confirmed chemical and physical interactions between CH, GE and BG. Thermogravimetric analysis (TGA) demonstrated that the DD of CH had a positive influence in the thermal degradation behavior of the biocatalysts up to 200 degrees C, which represents the temperature range used in most enzymatic reactions (up to 100 degrees C) in the industrial scale applications.

关键词： Accelerated co-composting   Lignocellulosic food industry waste   Empty fruit bunches   Coffee ground   Palm oil mill sludge  

摘要： Time and storage space are the main constraints facing by the current Malaysia composting industries which are handling lignocellulosic food industry waste such as empty fruit bunch (EFB), coffee ground (CG) and palm oil mill sludge (POMS). To develop an efficient accelerated composting method for lignocellulosic food industry waste in Malaysia, a new approach which combined two distinct technologies to achieve rapid composting;(i) co-composting with combination of different lignocellulosic materials and (ii) inoculation of the co-composting with mixture of microorganism were presented in this study. All the mixtures achieved thermophilic condition on the first week of composting, with 50% EFB + 50% CG combination recorded the highest temperature of 56 degrees C. The mixtures with initial C/N ratios within 25-35 showed the highest reduction in holocellulose, cellulose, hemicellulose and lignin content while compost mixture with initial C/N ratio more than 50 had a minimal reduction. The C/N ratio for 50% EFB + 25% CG + 25% POMS combination was reduced to less than 20 after 4 weeks of co-composting process while the other treatments needed longer composting duration. During thermophilic phase, higher population of bacteria (10(7)-10(8) CFU/g DW) was observed, followed by fungi (10(5)-10(6) CFU/g DW) and actinomycetes (10(5)-10(6) CFU/g DW) populations. However, higher population of actinobacteria (10(4)-10(6) CFU/g DW) compared to bacterial (10(4)-10(5) CFU/g DW) and fungal (10(3)-10(4) CFU/g DW) was found during latter stages. By reducing both the time and space required for composting lignocellulosic food industry waste, this accelerated co-composting method may be a viable option for food industries searching for a long-term, practical solution for solid biowaste disposal issues. Graphic

摘要： Background. One of the key elements of successful transplantation is effectively rinsing off the blood and preserving organs under controlled hypothermia. The aim of the study was to analyze the physicochemical parameters of Biolasol (Biochefa, Sosnowiec, Poland) and histidine-tryptophan-ketoglutarate (HTK) (Custodiol) solutions, which are recommended for perfusion and preservation of abdominal parenchymal organs. Methods. Biolasol and HTK solution were used for the study. The solutions were subjected to physicochemical analysis involving pH, density, osmolarity, viscosity, refractive index, zeta potential, hydrodynamic diameter, and rheological properties. Rheological parameters were associated with morphologic features of fluids. Results. HTK and Biolasol are non-Newtonian systems with pseudoplastic properties and yield stress. The solutions begin to flow under shear stress greater than the ultimate stress. In addition, a nonlinear relationship of their viscosity as a function of velocity gradient (shear rate) was observed. Conclusions. The solutions reproduce blood properties, which leads to the conclusion about their effective filling of the vascular bed and high efficiency in organ rinsing.

关键词： UV   Vis spectroscopy   Principal component analysis   Fluorescence spectroscopy   Coffee brew methods   Coffee roasting  

摘要： Effects of geographical origin of Coffee Arabica beans (Brazil, Colombia and Peru), roasting degree, particle size and different brewing methods (French press, chemex and cold brew) on physicochemical and spectral properties of coffee samples were investigated in this study. Analyses of pH, total phenolic content (TPC) and total antioxidant activity (TA), UV and fluorescence spectroscopy measurements were performed. Principal component analysis (PCA) was used to obtain the most effective parameters on chemical changes. Results indicated that the increase of roasting degree caused decrements in the intensities of UV-spectra because of the degradation of trigonelline and chlorogenic acid molecules while counterpart trend was observed in the fluorescence spectra due to formation of fluorescence Maillard reaction products (MRP) during roasting. French press and cold brew methods caused similar TPC (1873.33-3818.33 and 2648.88-3824.44 mu g/mL gallic acid equivalent, respectively) and TA (0.18-0.32 and 0.16-0.27 mu mol/mL Trolox equivalent, respectively) values whereas chemex method showed different physicochemical properties (TPC: 1008.88-3543.88 mu g/mL gallic acid equivalent and TA: 0.08-0.26 mu mol/mL Trolox equivalent). Roasting degree and brewing method-compared to other parameters-were the most discriminating factors on the basis of UV spectra and fluorescence spectra of coffee brew samples, respectively. All roasting degrees could be distinguished with the rate of 71.42% on PC1 and 23.45% on PC2 of total variance according to UV-spectra while chemex and French press-cold brew methods could be differentiated with the rate of 97.24% on PC1 and 1.79% on PC2 of total variance based on fluorescence spectra on PCA score graphs.

关键词： Biosorbent   Kinetics   Adsorption rate   Pseudo second order   Heavy metals  

摘要： Adsorption rate is a critical parameter in the design of effective biosorbent treatment systems for heavy metals removal. Though numerous studies have identified the physico-chemical properties of biosorbents that exert influence on the adsorption rate, such influence has not been mathematically defined, limiting the effective design of adsorption systems. This study quantifies the influence of biosorbent physico-chemical properties including, specific surface area, surface functional groups, pore size, pore volume and zeta potential on the adsorption rate in relation to three divalent metal cations. Mathematical equations were developed to predict the influence of physico-chemical properties on pseudo second order kinetic constant and thereby predict the adsorption rate. Tea factory waste and coconut shell biochar were mixed in different weight percentages to vary the physico-chemical properties under consideration. Four different initial metal ion concentrations were used. Relationship between pseudo second order kinetic constant at each concentration with physico-chemical properties was quantified using regression analysis. The experimental analysis revealed that among the physico-chemical properties, acidic surface functional groups had the most profound influence on sorption mechanisms. Reliability and accuracy of the predictive models were significantly improved when separate models were developed for two ranges of initial metal ion concentrations. The outcomes of this study will contribute to the effective design and optimization of biosorbent mixtures with the capacity to remove Pb2+, Cu2+ and Cd2+ in wastewater. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Smart MWCNT/cementitious composite   Electrical conductivity   Elevated temperature   Physicochemical properties   Piezoresistivity   Microstructure  

摘要： Piezoresistivity of smart carbon nanotube/cementitious composite has been experimentally investigated, but the piezoresistive performance had been rarely studied when exposed to elevated temperatures. In this study, the physicochemical and mechanical properties, and piezoresistive behaviours of multi-walled carbon nanotube (MWCNT) reinforced smart cementitious composite were investigated under heat treatments of elevated temperatures of 300 degrees C and 600 degrees C. The microstructures, crystal deterioration and thermal gravity relationships were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and thermos-gravimetric (TG) analysis. The results show that the compressive strength and elastic modulus of MWCNT/cementitious composite after heat treatments gradually decreased, especially under the high temperature of 600 degrees C. There was a sudden growth of fractional changes of resistivity (FCR) after heat treatment. The higher temperature treatments led to more extensive sudden increase in the piezoresistivity. In the linear part of the relationship curves of FCR to the strain, the gauge factor even increased at the temperature of 300 degrees C. Moreover, the mechanism for the altered piezoresistivity was fundamentally explained and discussed by the MWCNT purification and destructions of MWCNT, cement matrix and agglomerations after heat treatments. Therefore, the related outcomes will promote the understanding and application of smart MWCNT/cementitious composite for structural health monitoring (SHM) under extreme environments.

关键词： plasma-activated water   dielectric barrier discharge   reactive oxygen species   reactive nitrogen species   soil pH   water retention   water absorption   plasma agriculture  

摘要： Recently, the bactericidal and fungicidal effects of plasma-activated water (PAW) have been confirmed for its application in agriculture. Although the PAW application is beneficial in plant growth, no information is available about processes induced by PAW in soil. This paper gives the first experimental results about PAW's influence on selected physical and physical-chemical properties of soil. PAW was prepared using the dielectric barrier discharge (DBD) operating in the multistreamer mode at a frequency of 11 kHz. The total energy consumption was 60 J/ml. The obtained results show minimal changes in the natural water evaporation from the soil exposed to PAW, slower tap water absorption if a higher amount of PAW (16 doses per 10 ml to 90 g of the soil) is applied, as well as water retention in the soil of over 30%. The soil pH remains in the neutral range of values even at the highest applied PAW amount of 1.7 weight of soil, which represents the best conditions with respect to the plant growth. Thus, we can conclude that the PAW application, even at high amounts, has no negative influence on the physical and physical-chemical properties of soil and it can be safely applied in sustainable, environmentally friendly agriculture.

关键词： Water absorption  

摘要： This study aims to elucidate the effect of male date palm flower (MDPF) incorporation in the dough properties and biscuit characteristics. Farinograph analysis demonstrated a progressive increase in water absorption (56.85%-61%) and dough stability (1.88-20.25 min) with increasing MDPF quantity due to its wealth in dietary fiber. Biscuit formulations were prepared using 3, 6, and 9% MDPF powder and evaluated for their physico-chemical, textural, and sensory properties. The results have shown a significant increase (p < .05) in dietary fiber (1.22%-84.81%), protein (7.64%-8.30%), and ash content (1.30%-1.68%) coupled with a darkness increase (77.30-58.52) compared to the control. The textural analysis of doughs and biscuits showed that hardness increased with the increase in MDPF incorporation levels (2.52-5.26 N and 11.32-15.64 N, respectively). The sensory evaluation showed that up to 9% MDPF incorporation, the different sensory attributes were positively correlated, with more appreciation for the 6% fortified-biscuit. Owing to its nutritional value, the MDPF powder could be used as an ingredient for bakery food products in gastronomy. Practical applications The male date palm flowers (MDPF) are considered as an under-exploited by-product as they are discarded or sometimes used in animal feed. However, they present a rich matrix composed mainly of dietary fiber, protein, and minerals. Nowadays, consumers are searching for healthy and novel foods which push the industrials to invent new dietetic formulations using vegetable protein source and dietary fibers. The MDPF incorporation in biscuit formulation might contribute to reducing these vegetable wastes allowing their valorization as a nutritional and functional ingredient at the same time.

关键词： greases   organic thickener   Group I base oils   performance characteristics of greases  

摘要： A comprehensive study of urea greases obtained on the basis of Group I distillate oils, which have a viscosity in the range from 24.4 to 342.0 mm(2)/s at 40 degrees C, has been carried out. The results obtained have made it possible to reveal the dependence of various physicochemical parameters of greases (dropping point, ultimate strength, colloidal stability, wear rate) on the viscosity of the base oil and the structure of diurea used as a thickener. The revealed relations allow prediction of the properties of greases at the stage of selecting the initial components.

关键词： metallurgical dust   chemical composition   phase composition   structure   ceramic materials   hydrometallurgical extraction of zinc   zinc powder   pigments   micronutrients  

摘要： The chemical and phase compositions and the properties of metallurgical dust were studied and its structure and granulometric composition were determined. The physicochemical processes occurring during heat-treatment of the dust in the temperature interval 20 - 1200 degrees C were studied. The main directions for reprocessing of the investigated dust for purposes of obtaining useful products are proposed on the basis of the performed studies.