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关键词： Graphene  

摘要： Herein, we report the physicochemical characteristics and piezoresistive strain sensing performance of flexible thin film comprising graphene and bio-based thermoplastic polyurethane (TPU) prepared by solution cast method. A detailed analysis was carried to study the influence of graphene nanoplatelets on the morphological, thermal, mechanical, and electrical properties of TPU nanocomposite. Upon increasing the graphene nanoplatelets loading, the thermal stability and tensile properties improved remarkably, while glass transition temperature decreased slightly. Owing to better dispersion of graphene, the electrical conductivity was significantly increased, which broaden the utilization of the nanocomposite for various applications. The piezoresistive sensor was able to respond to various stress modes such as tapping, bending, and finger touch. The piezoresistive sensor was sensitive and achieved a gauge factor of 11. Sensor attached to finger, showed distinctive response upon bending at different angles and showed high stability and reproducibility even after >10,000 cycles under repetitive constant load. Also, the nanocomposite was able to detect any breakage or fracture in the form of change in electrical resistance. A combination of bio-based TPU and graphene offered improved physical properties and high sensing performance, which could be a potential material in flexible electronics and structural health monitoring systems.

关键词： Brazilian semiarid   Cyanobacterial morphotypes   Phosphorus   Salinity   Structural equation modeling   Zooplankton  

摘要： Understanding the importance of environmental variables on the dominance of cyanobacteria is crucial for appropriately managing water resources. Although studies about temperate and subtropical regions show a high influence of nutrients and temperature on blooms, this relationship is still unclear for the tropics. Accordingly, we hypothesized that nutrients and temperature arc the main factors driving cyanobacterial blooms in tropical reservoirs, and those relationships are intensified by the zooplankton. To test these hypotheses, we constructed a structural equation model based on the monitoring of ten reservoirs from Northeast Brazil. We analyzed the effects of physicochemical variables and zooplankton on cyanobacterial blooms and the biomass of four morphotypes. Cyanobacterial biomass varied within the reservoirs, with bloom records (0.2-268.4 mg L-1) in all of them, primarily constituted by the colonial morphotype, followed by picocyanobacteria, heterocyted, and non-heterocyted filaments. The cyanobacterial community was driven mainly by chemical variables (55.14% of the variation), followed by physical (48.28%), and zooplankton (39.47%). Through the structural equation model, we demonstrated that total cyanobacterial biomass, as well as the morphotypes, were mainly influenced by omnivorous crustaceans and total dissolved phosphorus. Solar radiation, air temperature, mixing zone, and salinity were important to explain the biomass of the morphotypes. The model explained most of the variation in the picocyanobacterial blooms (79.8%), followed by total cyanobacteria (62.4%), heterocyted filaments (59.1%), non-heterocyted filaments (58.2%), and coccoids (55.1%). Zooplankton groups were also influenced by the physicochemical variables, which presented direct and indirect effects on cyanobacteria. Given the predictions of increased eutrophication, warming, and salinization, cyanobacterial blooms will become more intense in tropical reservoirs. Thus, restoring measures

关键词： Plant derived food   Plant biology   Biomass   Animal feed   Energy  

摘要： Torrefaction as a thermal pretreatment was conducted on oat hull, canola hull, and barley straw in a fixed-bed reactor at temperatures in the range of 220-300 degrees C and residence times of 30-60 min to study impacts of these two parameters on physicochemical and fuel properties of biomass. The chemical nature of torrefied biomass was analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, solid-state C-13 nuclear magnetic resonance spectrometry (C-13 NMR), and X-ray photoelectron spectroscopy, while the morphology of the sample was analyzed by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analyses. The results indicated that torrefaction pretreatment significantly elevated the fuel ratio in all biomasses and reduced cellulose crystallinity. Thermogravimetric analysis (TGA) showed that significant decomposition of biomass occurred under the most severe conditions in the following order: canola hull, barley straw, and oat hull. A remarkable decrease in volatile matter and increase in fixed carbon content are also observed from the TGA curve for torrefied biomasses. C-13 NMR and FTIR analysis of torrefied biomass samples demonstrated that the cross-linking, devolatilization, and carbonizing of biomass during the torrefaction process might be accountable for low mass yield. According to SEM results, a more fragmented and tubular structure was obtained at higher temperature because of thermal cracking and degradation of lignin, respectively, which made the biomass easy to grind. Inductively coupled plasma-mass spectrometry analysis showed that barley straw contains the highest amount of minerals (44.5 mg/g) followed by oat hull (15.5 mg/g) and canola hull (8.3 mg/g), when torrefied at 260 degrees C for 60 min. In addition, torrefaction significantly increases the alkaline and other essential element concentrations in torrefied samples. The BET surface area of torrefied biomass was found to be two to three times higher than

关键词： Pine nut shell   pyrolysis temperature   screw reactor   biochar adsorption   energy yield  

摘要： Pyrolysis experiments of pine nut shells (PNSs) were carried out in a screw reactor at 300-700 degrees C with approximately 98% energy yields. The analysis results showed that higher temperatures result in elevated heating values (HVs) of products but reduced biochar and bio-oil yields. The HVs of pyrolytic gas were remarkably influenced by proportions of CH4 and H-2. Bio-oil of PNSs consisted primarily of phenols, acids, aldehydes, ketones, furans, and aromatic hydrocarbons. Five hundred degree Celsius was considered as optimal temperature for PNS pyrolysis, and biochar was the primary product with a yield of 37.11% and better Cu2+, Ni2+, and Zn2+ adsorption properties. [GRAPHICS] .

关键词： Microgels   Silver nanoparticles   3-nitroaniline   Catalytic reduction   Phenylenediamine  

摘要： Poly(N-isopropylmethacrylamide-co-methacrylic acid) [P(NM)] network with colloidal size was obtained by emulsion polymerization. Chemical reduction of silver nitrate via NaBH4 produced silver nanoparticles within network. Both P(NM) and Ag-P(NM) were characterized. 3-nitmaniline (3-NA) was reduced with NaBH4 in presence of Ag-P(NM) to test its catalytic activity. Catalytic efficacy of Ag-P(NM) was investigated under various conditions of NaBH4, 3-NA and Ag-P(NM). Dependence of rate constant upon NaBH4 and 3-NA describes that 3-NA reduction takes place by following Langmuir Hinshelwood mechanism. Acquired kinetic data verifies that Ag-P(NM) is an efficient catalyst for reduction of 3-NA. Catalytic activity of Ag-P(NM) was found tunable via lead nitrate concentration.

关键词： Vanadium oxide (VO2) nanoparticles   Methylene blue   Dye adsorption   Process modeling optimization  

摘要： Vanadium oxide nanoparticles (VO2-NPs) were synthesized and utilized as an adsorbent against methylene blue (MB) from aqueous environment. Three substantial variables, pH, mixing time, and VO2 dose, were considered in the process modeling accomplished by Box-Behnken design (BBD). The quadratic model revealed that the VO2-NPs dose plays the most significant role. The model optimization predicts a 96.3% MB removal when pH, VO2-NPs dosage, and contact time were adjusted to 6, 0.5 g/L, and 30 min, respectively. The sorption capacity of VO2-NPs raised rapidly from 49.6 mg/g to 235.7 mg/g by increasing the initial MB concentration from 25 to 200 mg/L, respectively. The best fitted kinetic model was the pseudo-second order, while the well fitted Langmuir model showed a q(max). of 240.5 mg/g. The study of the temperature effect revealed that increase of the temperature had a positive impact on the removal efficiency. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 1-Ethylimidazole   Physicochemical properties   H-1 NMR   H-bonded interactions   COSMO-RS prediction  

摘要： In order to explore the properties and molecular interactions in the binary systems of 1-alkylimidazole with molecular solvents, the system of x 1-ethylimidazole (herein referred to as 1-Eim) + (1-x) water, in the temperature range (288.15-328.15) K, the density rho, sound velocity u viscosity eta, refractive index n(D), pH and conductivity K, and the H-1 NMR delta(H), were measured at atmospheric pressure: the excess molar enthalpy H-m(E), the excess molar Gibbs free energy G(m)(E), and the excess molar entropy S-m(E), were predicted from the COSMO-RS model. The experimental and predicted properties indicate that the H-bonded interactions arc the predominant interactions over the whole composition range. 1-Eim protons share more electron densities than water protons via the H-bonds, which are stronger between dissimilar molecules than between similar ones. The stable H-bonded structure of water molecules breaks when x is about 0.1, while the stable H-bonded structure of 1-Eim molecules forms when x is about 0.9. Temperature affects the H-bonded interactions more in the case of dissimilar molecules than similar molecules, especially in the water-rich region. The real mixing process is an enthalpy-driving spontaneous process with the liquid structure more ordered. A lower temperature more greatly benefits spontaneous mixing. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Wheat A- and B-starch   Molecular weight   Repeated heat-moisture  

摘要： The effects of continuous heat-moisture treatment (CHM) and repeated heat-moisture treatment (RHM) on multi-scale structure, physicochemical and digestibility properties of wheat A- and B-starch were investigated and compared. Both A- and B-starch granules maintained integrity after repeated and continuous modification. Changes in starch molecules induced the diversification of crystal structure and physicochemical properties. Crystal type of CHM and RHM starches maintained the original A-type while the crystallinity decreased after treatmnt. For wheat A-starch, the RS and RDS contents of RHM starches were obviously lower than native ones while the SDS content increased. Meanwhile, the RDS and SDS contents of treated B-starch were significantly higher than native ones but the RS content was lower. At the same conditions, B-starches exhibited a lower relative crystallinity, lower viscosity parameters, lower T-o, T-c, T-p and Delta H values than A-starches. In general, the repeated heat-moisture treated samples obtained superior characteristics than continuous treated ones, and the results of A- and B-starch varied greatly. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Bone biochar   FeOx/MnOx   Heavy metals   Wastes utilization   Adsorption mechanism  

摘要： The value-added utilization of waste resources to synthesize functional materials is important to achieve the environmentally sustainable development. In this work, novel micro-nano FeOx- and MnOx-modified bone biochars derived from waste bone meal were obtained at 300 degrees C, 450 degrees C and 600 degrees C, and applied to remove Cd (II), Cu(II) and Pb(II) from aqueous solutions. The results showed that the pyrolysis temperature greatly influenced the specific surface area (SSA), micropore creation, functional groups and heavy metal sorption capacities of FO-BCs and MO-BCs. The effects of solution pH, ionic strength, humic acid (HA), kinetics and thermodynamics on heavy metals adsorption were investigated. Langmuir and pseudo-second order kinetics models fit the adsorption data well, and the FO-BC-450 and MO-BC-600 displayed the highest sorption capacity for Cd(II) (151.3 mg/g and 163.4 mg/g), Cu(II) (219.8 mg/g and 259.0 mg/g) and Pb(II) (271.9 mg/g and 407.2 mg/g), respectively. Due to the dissolved partial hydroxyapatite (HAP), carbonate-bearing hydroxyapatite (CHAP) and the catalysis of Fe(NO3)(3), the FO-BCs with higher SSA than the MO-BCs, whereas the sorption capacity displayed an opposite trend. The chemical complex, cation-pi bonds, ion exchange and coprecipitation were the dominant mechanisms for metals adsorption. Overall, waste bone resource co-pyrolysis with Fe(NO3)(3)/KMnO4 impregnation is a promising and high-efficient adsorbents for the remediation of heavy metals-contaminated waters.

关键词： Tartary buckwheat starch   Quercetin   Digestibility   Rheological properties   Thermal properties  

摘要： The effects of polyphenols on the physicochemical properties and in vitro digestibility of Tartary buckwheat starch (TBS) remain scarce. In this study, the rheological, thermal properties, and in vitro digestibility of pregelatinized TBS (pre-TBS) with quercetin complexation at various concentrations were characterized. It was found that quercetin complexation increased the shearing resistance and viscosity of pre-TBS. Both SEM and TGA results revealed a more compact and stable structure of starch-quercetin complex in comparison to pre-TBS. The non-inclusive complex with higher crystallinity was formed through hydrogen bonds, which showed by XRD and FT-IR results. Additionally, complexes exhibited the lower digestion rate and digestion velocity constant, and the resistant starch content of complex (with 10% quercetin addition) was the highest. Therefore, quercetin complexation could improve the thermal and rheological properties, and decrease in vitro digestibility of pre-TBS, which could provide a theoretical basis for functional food development. (C) 2020 Elsevier B.V. All rights reserved.