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关键词： Hematite nanoparticles   Co-precipitation   Capping agent   MTT assay   Photocatalytic dye degradation   DPPH assay  

摘要： Capping agents play a vital role in controlling the size, morphology, and monodispersity of nanoparticles. To understand a comprehensive overview of the influence of capping on the structure and properties of hematite nanoparticles (HNPs), we have synthesized hematite nanoparticles (HNPs) with narrow size distribution by an economic co-precipitation method using capping agents like sodium citrate, Polyvinyl Pyrrolidone (PVP) and starch. A comparative in-depth study of structure, morphology, and surface analysis along with thermal, optical, magnetic and electrochemical properties of synthesized capped and uncapped HNPs has been performed. The effect of capping agents on photocatalytic and antioxidant activities along with cytotoxicity of all fabricated nanoparticles was studied against MDA-MB-231 cell line causing breast cancer along with flow cytometry. Results revealed a definite improvement in grain size, crystallinity, optical, thermal and magnetic properties of HNPs is due to efficient capping. PVP has reduced the maximum of crystalline size up to 23% of HNPs and removed 98.80% of dye from wastewater among all capping agents. Our findings also suggest that PVP capped HNPs proved to be cytotoxic to the cancer cell line. Taken together, our studies will be helpful to understand the role of capping agents in determining properties of HNPs that can further help in designing engineer HNPs.

关键词： Geopolymer   Volcanic pozzolan   Blast-furnace slag   Physicochemical properties   Construction materials  

摘要： This research focuses on the synthesis and characterization of geopolymers based on French pozzolan (P) by adding two types of blast-furnace slags with different chemical compositions (L1 and L2). The slags amount varied between 0% and 50%. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) were used as the alkaline activator. The physicomechanical properties of the synthesized geopolymer cements were evaluated. Complementary studies using X-ray diffractometry (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were also performed. The results found proved that adding the two slags to the pozzolan led to considerable improvement in the geopolymers' physicomechanical properties. In comparison, the L1 slag addition, more magnesian than L2, favored the formation of more quantity of amorphous phase and also the mineral phase of hydrotalcite-type, which justifies the high geopolymers' physicomechanical characteristics based on L1 slag (series 1) compared with those synthesized from L2 slag (series 2) obtained at 28 days of curing.

关键词： Ethanol   Biofuel   Thermodynamics   Phase equilibrium   NRTL   UNIFAC   Chemical technology  

摘要： The use of renewable biofuels is a necessity today and entails the improvement and optimization of related processes. The work presents new thermodynamic parameters necessary to optimize the operation of internal combustion engines, improve characteristics and predict the properties of biofuels. Based on the obtained liquid-liquid equilibrium (LLE) data, binodal curves and surfaces are constructed for a system containing ethanol, propionic acid, ethyl propionate and water at 293.15 K and 303.15 K and atmospheric pressure, as well as model calculations of vapor-liquid equilibrium (VLE) data were carried out according to literature results on compositions of chemically equilibrium (CE) mixtures. The results of modeling on liquid-phase and vapor-liquid equilibrium using NRTL and UNIFAC models respectively are presented. A comparative analysis of the results under the temperature conditions of this study is given.

关键词： Biofilm   Breakthrough curve   Limestone   Retention profile  

摘要： There is a paucity of information regarding the interaction between GONPs and natural aquifer sediments. Therefore, batch and column experiments were carried out to determine the transport, retention and attachment behavior of GONPs with the surfaces of native aquifer sediments. The experiments were performed with sediments comprising contrasting mineralogical features (sand grains, quartz and limestone sediments), at different temperatures, ionic strength and compositions. Uniquely, this research also investigated the effect of natural biofilm on the retention behavior of nanoparticles in porous media. The retention rate of GONPs at 22 degrees C was higher than at 4 degrees C. Moreover, there was greater retention of GONPs onto the surfaces of collectors at higher ionic strengths and cation valence. The retention profiles (RPs) of GONPs in pristine porous media at low ionic strength were linear, which contrasted with hyper-exponential shape of RPs at high ionic strength. The size distribution analysis of retained GONPs showed decreasing particle diameter with increasing distance from the column inlet at high ionic strength and equal diameter at low ionic strengths. The GONP retention rate was higher for natural porous media than for sand, due to the presence of metal oxides heterogeneities. The presence of biofilm on porous media increased the retention rate of GONPs when compared to the porous media in the absence of biofilm.

关键词： RP-3 kerosene   Surrogate   Skeletal mechanism   Spray   Engine  

摘要： RP-3 kerosene is a widely used fuel for civil and military transportation in China. Two RP-3 kerosene surrogates (UM1 and UM2) were proposed by genetic algorithm optimization methodology, aiming to simulate viscosity, density, surface tension, cetane number, lower heating value, H/C ratio and molecular weight along with sooting tendency under spray and engine relevant conditions. The RP-3 kerosene surrogates were composed of four components including n-dodecane, 2,2,4,6,6-pentamethylheptane, decalin and n-propylbenzene (UM1, 0.3374/0.3042/0.1954/0.163. UM2, 0.1449/0.3706/0.2059/0.0195/0.2591 by mole fraction). The carbon number of n-dodecane and 2,2,4,6,6-pentamethylheptane was both much closer to that of the real RP-3. Based on the proposed surrogates, a skeletal RP-3 surrogate chemical reaction mechanism was developed by decoupling methodology. The skeletal RP-3 surrogate mechanism was reduced only including 89 species and 225 reactions, which was efficient and reliable in CFD simulation. The surrogate models were validated during spray process under vapor and nonevaporating environment. The skeletal mechanism was verified against the foundational experiments such as ignition delay times, species concentrations and laminar flame speed under wide conditions. The applicability of skeletal mechanism was also well verified with our test data from a real compression-ignition engine. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Lotus-seed starch nanoparticles   High-pressure homogenization   Structural properties  

摘要： In previous studies, we successfully prepared lotus-seed starch nanoparticles (LS-SNPs) using enzymatic methods. To further improve their performance, we studied the structural, physical and chemical properties of LS-SNPs prepared by high-pressure homogenization (HPH)-assisted enzymatic hydrolysis (EH). HPH treatments at different pressures and frequencies have a significant effect on the particle size and molecular weight of LS-SNPs. Structural analyses showed that LS-SNP and H-LS-SNP both comprised B-type starch crystals. As the homogenization pressure and frequency were increased, the relative crystallinity of H-LS-SNP first increased and then decreased, indicating that HPH treatment affected the double-helix structure of LS-SNPs. The results also show that moderate HPH treatment was beneficial for enzymatic hydrolysis, but when the HPH treatment was further increased, it destroyed the ordered structure of LS-SNPs. Our research showed that H-LS-SNPs with the smallest particle size and the highest crystallinity were obtained under pressure of 150 MPa, a homogenization frequency of five times the original, and a material-to-liquid ratio of 3%. The results indicate that HHP-assisted EH is a suitable method for preparing SNPs. These findings provide new ideas for the preparation of SNPS to meet the needs of food industry. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Chitosan   Xanthan gum   Polyelectrolyte complex   Drug entrapment   Polymer crosslinking   Controlled drug release  

摘要： The effect of the entrapment procedure of a poorly water soluble drug (ibuprofen) on physicochemical and drug release performances of chitosan/xanthan polyelectrolyte complexes (PECs) was investigated to achieve controlled drug release as the ultimate goal. The formation of PECs for two drug entrapment procedures (before or after the mixing of polymers) at pH 4.6 and 5.6 and three chitosan-to-xanthan mass ratios (1:1, 1:2 and 1:3) was observed by continuous decrease in conductivity during the PECs formation and increased apparent viscosity and hysteresis values. The most extensive crosslinking was observed with ibuprofen added before the PECs formation at pH 4.6 and chitosan-to-xanthan mass ratio 1:1. The PECs prepared at polymers' mass ratios 1:2 and 1:3 had higher yield and drug entrapment efficiency. DSC and FT-IR analysis confirmed ibuprofen entrapment in PECs and the partial disruption of its crystallinity. All ibuprofen release profiles were similar, with 60-70% of drug released after 12 h, mainly by diffusion, but erosion and polymer chain relaxation were also included. Potentially optimal can be considered the PEC prepared at pH 4.6, ibuprofen entrapped before the mixing of polymers at chitosan-to-xanthan mass ratio 1:2, which provided controlled drug release by zero-order kinetics, high yield, and drug entrapment efficiency. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Rice starch   Proanthocyanidins   Non-covalent binding   Physicochemical properties   Digestibility  

摘要： Proanthocyanidins extracted from Chinese berry leaves (CBLPs) were heated with rice starch in aqueous solution to prepare polyphenols-starch complexes. The physicochemical properties of the complexes were characterized with XRD, DSC, RVA and FT-IR and starch constituents were also analyzed with an enzyme method. Results indicated that the addition of CBLPs destroyed the long ordered structure of rice starch rather than the short ordered structure, since the crystallinity decreased from 21.96% to 18.90% and the ratio of 1047 cm(-1)/1022 cm(-1) showed little difference, consistent with the lower Delta H of complexes with higher CBLPs content. Additionally, the CBLPs-rice starch complexes showed a significantly lower content of rapidly digested starch (RDS, 45.64 +/- 3.25%) than that of the native rice starch (67.76 +/- 2.15%). These results indicated that CBLPs complexes with rice starch might be a novel way to prepare functional starch with slower digestion.

关键词： Butane-1,4-diamine (DAB)   Biogenic polyamines   X-ray diffraction   Vibrational spectroscopy   Theoretical calculations  

摘要： The results of Fourier Transform Infrared absorption and Raman spectroscopy studies are reported for solid and liquid neat butane-1,4-diamine (DAB) and for the molecule in different solvents. Ab initio molecular dynamics and static calculations are reported in the work as an interpretative tool for the measurements and provide an analysis of the relative population of DAB conformers, both in vacuo and in the liquid phase. X-ray diffraction data for liquid DAB are presented to further consolidate the interpretation of the conformation and structure of the biomolecule in the liquid phase. The study of DAB in polar solutions suggests a high level of structuring of the molecules in the liquid, as a consequence of the effect of solvent on the molecular charge distribution. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Supercritical impregnation   Polylactic acid (PLA)   Lignin nanoparticles   Cinnamaldehyde   Toxicity studies   Disintegration  

摘要： Poly (lactic acid)/lignin nanocomposites (PLA/Lig-Np) containing cinnamaldehyde (Ci) were obtained by a combination of melt extrusion and supercritical impregnation process. In this work, Ci impregnation tests were carried out in a high-pressure cell at 40 degrees C for 3 h using 12 MPa and 1 MPa min(-1) of depressurization rate, obtaining impregnation yields ranging from 5.7 to 10.8% w/w. Thermal, mechanical and colorimetric properties of the developed films were affected by the incorporation of lignin nanoparticles and the active compound, obtaining biodegradable plastic materials with a strong UV-light barrier property compared to PLA films. In addition, disintegrability tests under composting conditions confirmed the biodegradable character of nanocomposites developed. On day 23, a disintegration percentage greater than 90% was determined for all bionanocomposites. Finally, to establish the possible toxicity effect of the nanocomposites obtained, studies in vivo were performed in normal rats. Toxicity studies showed normal blood parameters after a single dose of nanocomposites. PLA/Ci/Lig-Np bionanocomposite films could be potentially applied to design biodegradable UV-light barrier materials for food packaging and biomedical applications. (C) 2020 Elsevier B.V. All rights reserved.