Particle Specific Surface Area Research Articles

PSVII-18 Change in the taxonomic composition of ruminal microflora against the background of copper and plant extract

Abstract Plant extracts are used in cattle diets to stimulate growth and immunity, while the unstable biochemical composition of plants contributes to the search for effective compositions that exhibit a synergistic effect. Objective of the study is the effect of an aqueous extract of oak bark (0.7 ml/kg of live weight) - group I, copper particles specific surface area 24 m2/g; 0.06 mg/kg of live weight - group II, their compositions (group III) on the taxonomic composition of the bacterial community of the rumen of cattle. Bulls had rumen fistulas Bos taurus at the age of 13 months (n = 5). Test samples of feed components were given with a concentrated portion of the main diet. Diet contain 60% - roughage (hay of Sudanese grass and alfalfa), 35% - concentrated feed (mixture of barley, wheat, sunflower husk, bran). The taxonomic composition of ruminal content was determined by NGS sequencing on a MiSeq device (Illumina, USA). It was found that the combined use of the extract and copper UFPs increases the concentration of representatives of Bacteroidetes in the rumen by 5.6%, the separate use of copper UFPs is by 20.7% (P ≤ 0.05), at the same time the values of representatives of Firmicutes decreased - by 7.2 and 24.7% (P ≤ 0.05) in comparison with the control. At the taxon level, the following classes prevailed: Bacilli (2.6%) in group I; Bacteroidia (17.0%) in II, in III - Bacteroidia (5.0%) in comparison with the control. In the experimental groups, at the genus level, a lower content of Streptococcus and the absence of Faecalibacterium were registered. Thus, the composition of plant extract and copper has an inhibitory effect on certain representatives of pathogenic bacteria. The results obtained indicate that the combined use of these substances is promising. This research was performed with financial support from the RSF (20-16-00088).

Effect of residual chlorine on iron particle formation considering drinking water conditions

In drinking water, residual chlorine is very likely to coexist with iron particles. However, the understanding of the effect of residual chlorine on iron particle formation in relation to different drinking water conditions is limited. Here, we found a significant competitive relationship between residual chlorine and dissolved oxygen (DO) during iron particle formation. Composition gave a good indicator of the extent of oxidation; with DO being the sole oxidant, the most abundant iron crystal in the particles formed was FeOOH (79.12%) followed by Fe3O4 (20.88%); in the presence of residual chlorine, however, the oxidation states of the iron crystals shifted upwards; the composition became as follows: FeOOH (50.64%), Fe3O4 (27.96%) and Fe2O3 (21.40%). The morphology of the particles formed showed interesting trends. In the presence of residual chlorine, the iron particles became denser and the specific surface area decreased. Particle size also exhibited a positive correlation with the chlorine concentration. The iron particle's specific surface areas formed with and without residual chlorine were 41.11m2/g and 61.30 m2/g, respectively. Linear regression also showed a good linear relationship between concentrations of iron ion and residual chlorine and the turbidity of the resulting water sample. Residual chlorine affects iron particle formation through different aspects, especially so when considering the interaction between residual chlorine with other oxidants and the resulting change in morphology. Runs of solutions with a high chlorine concentration through the pipe network could potentially act as a maintenance treatment.

A novel preparation of high purity TiO2 from industrial low concentration TiOSO4 solution via short sulfate process

High purity TiO2 was prepared by authigenic seed thermal hydrolysis route from industrial low concentration titanyl sulfate solution via the short sulfate process. The hydrolysis conditions had important influences on the hydrolysis process. The appropriate induced water volume ratio and hydrolysis time were conducive to form appropriate quantity and quality of hydrolysis seeds, adjust and control the precipitation, crystal growth, particle growth and aggregation velocity for the hydrated TiO2, which could obtain the hydrated TiO2 with smaller average particle size and specific surface area. These effects were beneficial to reduce the adsorption of impurities, and improve the purity of TiO2. The hydrolysis conditions had internal influencing relationship between them. The optimized hydrolysis conditions were the induced water volume ratio was of 60%, the hydrolysis time was of 120 min, and the high purity, monodisperse titanium dioxide over 99.98% content could be obtained.

SHS-Derived Powders by Reactions' Coupling as Primary Products for Subsequent Consolidation.

The capability of self-propagating high-temperature synthesis (SHS) to produce powders that are characterized by a high sintering ability, owing to high heating and cooling rates inherent to the exothermic reaction, is of a special interest for the industry. In particular, SHS-derived powders comprise a significant defect concentration in order to effectively enhance the mass transfer processes during the sintering, which allows for the successful consolidation of difficult-to-sinter materials at relatively low sintering temperatures. From this perspective, the design of precursors suitable for sintering, synthesis in a controlled temperature regime and the optimization of geometrical and structural parameters of SHS powders as a potential feedstock for the consolidation is of key importance. Here, we report on the comparative studies concerning the SHS processing of composites for advanced powder metallurgy techniques. The synthesis and sintering peculiarities of the SHS through coupled reactions in the Me’O3(WO3,MoO3)-Me’’O(CuO,NiO)-Mg-C, Ti-B-Al12Mg17 systems are comparatively reviewed. The SHS coupling approach was used for the preparation of powders with a tuned degree of fineness (a high specific surface area of particles), a high-homogeneity and a controllable distribution of elements via both the regulation of the thermal regime of combustion in a wide range and the matching of the thermal and kinetic requirements of two interconnected reactions. Microstructural features of the powder feedstock greatly contributed to the subsequent consolidation process.

Size and surface effects of hexagonal boron nitrides on the physicochemical properties of monolithic phase change materials synthesized via sol–gel route

Monolithic shape-stabilized phase change materials (ss-PCMs) are among the most promising materials to store large amounts of solar energy, waste heat and off-peak electricity as heat in energy-saving buildings, battery- and water-heating systems. Generally, graphite-like additives, such as hexagonal boron nitride platelets (BN), are used to increase the thermal conductivity of ss-PCMs. However, it is still unknown which particle size and surface type of graphite-like additives increase the thermal conductivity of ss-PCMs to the highest extent. Here, we present the first experimental study about the influence of BN with different particle sizes and specific surface areas on the physicochemical properties of ss-PCMs synthesized via the sol–gel route. With a BN particle size of 25 µm, the average thermal conductivity of ss-PCMs containing 5–20 wt% BN increased by 57% when compared to the same ss-PCMs prepared with smaller BN particles (3 µm). This effect possibly results from the stronger exfoliation of the larger BN particles during synthesis and a larger amount of BN particles ordered in the same alignment in the silica structure. BN particles larger than 25 µm hinder the formation of mechanically stable silica structures. Smaller BN particles lead to higher viscous reaction mixtures with shorter gelation times and, thus, result in smaller silica macropores with diameters below 1 µm and higher compressive strengths of ss-PCMs up to 2.4 MPa at 10 °C and 1.7 MPa at 30 °C. An increasing specific surface area of BN up to 20 m2/g decreases the thermal conductivity by 0.11 W/mK (30 °C) and the compressive strength by 0.28 MPa (30 °C) of ss-PCMs with 20 wt% BN because of more BN agglomeration. Therefore, ss-PCMs containing 20 wt% BN with a particle size of 25 µm and a specific surface area of 3 m2/g have the highest thermal conductivity of 1.14 W/mK at 10 °C and 0.62 W/mK at 30 °C, but a 0.7–0.3 MPa lower compressive strength (10 °C) than the ss-PCM synthesized using 3 µm sized BN particles and specific surface areas of 12–20 m2/g.

Process analysis of SO3 removal by Ca(OH)2 particles from flue gas

SO3 in coal-fired flue gas will cause equipment corrosion and the emission of sulfuric acid mist. The performance of injecting the alkaline adsorbent into the flue gas to remove SO3 is affected by the adsorption of SO2 in the flue gas. Taking Ca(OH)2 as a typical alkaline adsorbent, a model describing the adsorption of SO3 and SO2 by Ca(OH)2 particles was established, based on the combination of the product-island-growth model and the grain model. The parameters in the model were determined by the experimental data of adsorption in the fixed-bed reactor. The adsorption process of a single Ca(OH)2 particle was studied by numerical simulation. The adsorption of SO3 and SO2 was found to involve two stages: (1) In the early stage when there existed unreacted grain surface in the particle, SO3 and SO2 mainly reacted with the left fresh grain surface. The SO3 adsorption was controlled by internal pore diffusion and surface reaction, in which internal pore diffusion played a major role. The SO3 adsorption showed a shrinking core mode. The SO2 adsorption was controlled by internal pore diffusion and surface reaction and occurred throughout the entire particle. The SO3 adsorption selectivity at the outer surface of the particle was the highest, and decreased with a decreasing dimensionless particle radius R/R0. (2) In the later stage when the grain surface was completely reacted, the SO3 adsorption was controlled by internal pore diffusion and product-layer diffusion, in which product-layer diffusion played a major role. The SO2 adsorption was controlled by product-layer diffusion. The product-layer diffusion coefficient in the SO3 adsorption process was significantly higher than that of the SO2 adsorption, so SO3 was still significantly adsorbed in the later stage. The adsorption process of Ca(OH)2 under different particle structure parameters showed that decreasing the particle radius and increasing the particle porosity and specific surface area increased the SO3 removal efficiency as well as the total conversion of Ca(OH)2. Decreasing the particle radius and the specific surface area and increasing the particle porosity increased the SO3 adsorption selectivity by Ca(OH)2. When preparing industrial adsorbents, the optimization of the particle porous structure should be given attention.

Grand canonical Monte Carlo simulations of hydrogen adsorption in carbon aerogels

Hydrogen storage plays a fundamental role in the future hydrogen energy system, and carbon aerogel is one of the most potential hydrogen storage materials because of its high gravimetric and volumetric density on hydrogen adsorption. In this paper, the amorphous structure of carbon, obtained by a numerical simulation process by using the molecular dynamic and Monte Carlo methods, as well as the primary unit method, was intercepted as a sphere structure for numerical annealing to build a carbon nanosphere, which serves as the basic unit to reconstruct the carbon aerogel's skeleton by the Diffusion Limited Cluster Aggregation (DLCA) method. The hydrogen adsorption in carbon aerogel was simulated by using the self-coding parallel grand canonical Monte Carlo (GCMC) method. The influences of particle diameter, density, temperature, pressure, and specific surface area on the hydrogen adsorbing capacity in carbon aerogel were analyzed in detail. The results showed that the carbon aerogel's hydrogen storage capacity with a specific surface area of 2680 m2/g could reach 4.52 wt % at 77 K and 3.0 MPa.

Plastic viscosity of cement mortar with manufactured sand as influenced by geometric features and particle size

This paper investigates the plastic viscosity of cement mortar with manufactured sand (MS) concerning the influences of geometric features and particle size of MS. The geometric features, including overall shape, angularity and roughness, of MS with various particle sizes were evaluated by aspect ratio, convexity area ratio, convexity perimeter ratio and circularity. The plastic viscosity of cement mortar was calculated based on the Bingham model. Results show that the combined effects of overall shape, angularity and roughness provide coarser MS particles with lower circularity. In terms of relative plastic viscosity, Robinson model shows optimal fittings for all mixtures and is thus used to determine the packing fraction of MS under shearing. From the particle packing viewpoint, shear-induced orientation increases the packing fraction of non-spherical MS particles from the random loose packing fraction and the influence is increasingly prominent with the decrease of circularity. The relative volume fraction is an important parameter influencing the relative plastic viscosity of mixtures with MS while the relative paste film thickness (R_PFT), calculated from the real packing fraction and specific surface area (SSA), is found as the dominating factor. The dependence of plastic viscosity of cement mortar on geometric features and particle size of MS can be attributed to their influences on the packing fraction and SSA of particles.

Predicting the impact of biochar on the saturated hydraulic conductivity of natural and engineered media

If biochar is applied to soil or stormwater treatment media, the saturated hydraulic conductivity (K) may be altered, which is a critical property affecting media performance. While a significant number of studies document biochar's effect on a porous medium's K, predictive models are lacking. Herein models are advanced for predicting K for repacked natural soil and engineered media when amended with biochar of various particle sizes and application rates. Experiments were conducted using three repacked natural soils, two uniform sands, and a bioretention medium amended with a wood biochar sieved to seven different biochar particle size distributions and applied at three rates. Experimental measurements showed a strong positive correlation between the interporosity of each medium and K. Across all media, the classic Kozeny-Carman (K–C) model predicted K and the relative change in K because of biochar amendment for each medium best. For soils alone, a recently developed model based on existing pedotransfer functions was optimal. The K–C model error was improved if the particle specific surface area was increased for large biochar particles, which indicates the importance of biochar particle shape on pore structure and K. X-ray Computed Tomography was coupled with pore network modeling to explain the unexpected decrease in K for sands amended with medium and large biochar. While biochar increased interporosity, mean pore radii decreased by ~25% which reduced K. The X-ray measurements and pore network modeling help to explain anomalous results reported for biochar-amended sands in other studies.

Improved photocatalytic activity of SnO2-TiO2 nanocomposite thin films prepared by low-temperature sol-gel method

The objective of this research was to investigate how the photocatalytic activity of pure TiO2 can be improved by SnO2 modification. Different molar ratios of tin to titanium were prepared. The correlation between tin concentration and structural properties was investigated to explain the mechanism of photocatalytic efficiency and to optimize the synthesis conditions to obtain enhanced activity of the SnO2-modified TiO2 photocatalysts under UV-irradiation. The SnO2-modified TiO2 photocatalysts were prepared by a low-temperature sol-gel method based on organic tin and titanium precursors. The precursors underwent sol-gel reactions separately to form SnO2-TiO2 sol. The sol-gels were deposited on a glass substrate by a dip-coating technique and dried at 150 °C to obtain the photocatalysts in the form of a thin film. To test the thermal stability of the material, an additional set of photocatalysts was prepared by calcining the dried samples in air at 500 °C. The photocatalytic activity of the samples was determined by measuring the degradation rate of an azo dye. An increase of up to 30% in the photocatalytic activity of the air-dried samples was obtained when the TiO2 was modified with the SnO2 in a concentration range of 0.1–1 mol.%. At higher SnO2 loadings, the photocatalytic activity of the photocatalyst was reduced compared to the unmodified TiO2. The calcined samples showed an overall reduced photocatalytic activity compared to the air-dried samples. Various characterization techniques (UV-Vis, XRD, N2-physisorption, TEM, EDX, SEM, XAS and photoelectrochemical characterization) were used to explain the mechanism for the enhanced and hindered photocatalytic performances of the SnO2-modified TiO2 photocatalysts. The results showed that the nanocrystalline cassiterite SnO2 is attached to the TiO2 nanocrystallites through the Sn-O-Ti bonds. In this way, the coupling of two semiconductors, SnO2 and TiO2, was demonstrated. Compared to single-phase photocatalysts, the coupling of semiconductors has a beneficial effect on the separation of charge carriers, which prolongs their lifetime for accessibility to participate in the redox reactions. The maximum increase in activity of the thin films was achieved in the low concentration range (0.1–1 mol.%), which means that an optimal ratio and contact of the two phases is achieved for the given physical parameters such as particle size, shape and specific surface area of the catalyst.

The retrieval of snow properties from SLSTR Sentinel-3 – Part 1: Method description and sensitivity study

Abstract. The eXtensible Bremen Aerosol/cloud and surfacE parameters Retrieval (XBAER) algorithm has been designed for the top-of-atmosphere reflectance measured by the Sea and Land Surface Temperature Radiometer (SLSTR) instrument on board Sentinel-3 to derive snow properties: snow grain size (SGS), snow particle shape (SPS) and specific surface area (SSA) under cloud-free conditions. This is the first part of the paper, to describe the retrieval method and the sensitivity study. Nine pre-defined SPSs (aggregate of 8 columns, droxtal, hollow bullet rosette, hollow column, plate, aggregate of 5 plates, aggregate of 10 plates, solid bullet rosette, column) are used to describe the snow optical properties. The optimal SGS and SPS are estimated iteratively utilizing a look-up-table (LUT) approach. The SSA is then calculated using another pre-calculated LUT for the retrieved SGS and SPS. The optical properties (e.g., phase function) of the ice crystals can reproduce the wavelength-dependent and angular-dependent snow reflectance features, compared to laboratory measurements. A comprehensive study to understand the impact of aerosols, SPS, ice crystal surface roughness, cloud contamination, instrument spectral response function, the snow habit mixture model and snow vertical inhomogeneity in the retrieval accuracy of snow properties has been performed based on SCIATRAN radiative transfer simulations. The main findings are (1) snow angular and spectral reflectance features can be described by the predefined ice crystal properties only when both SGS and SPS can be optimally and iteratively obtained; (2) the impact of ice crystal surface roughness on the retrieval results is minor; (3) SGS and SSA show an inverse linear relationship; (4) the retrieval of SSA assuming a non-convex particle shape, compared to a convex particle shape (e.g., sphere), shows larger retrieval results; (5) aerosol/cloud contamination due to unperfected atmospheric correction and cloud screening introduces underestimation of SGS, “inaccurate” SPS and overestimation of SSA; (6) the impact of the instrument spectral response function introduces an overestimation into retrieved SGS, introduces an underestimation into retrieved SSA and has no impact on retrieved SPS; and (7) the investigation, by taking an ice crystal particle size distribution and habit mixture into account, reveals that XBAER-retrieved SGS agrees better with the mean size, rather than with the mode size, for a given particle size distribution.

An Investigation on Spray-Granulated, Macroporous, Bioactive Glass Microspheres for a Controlled Drug Delivery System.

Bioactive glass (BG) has been regarded as an excellent candidate for biomedical applications due to its superior properties of bioactivity, biocompatibility, osteoconductivity and biodegradability. Thus, in this study, we aimed to fabricate drug carriers that were capable of loading therapeutic antibiotics while promoting bone regeneration using macroporous BG microspheres, prepared by a spray drying method. Characterizations of particle morphology and specific surface area were carried out via scanning electron microscopy and nitrogen adsorption/desorption isotherm. Evaluations of in vitro bioactivity were performed based on Kokubo’s simulated body fluid to confirm the formation of the hydroxyapatite (HA) layer after immersion. In addition, the in vitro drug release behaviors were examined, using tetracycline as the therapeutic antibiotic in pH 7.4 and 5.0 environments. Finally, the results showed that BG microspheres of up to 33 μm could be mass-produced, targeting various therapeutic situations and their resulting bioactivities and drug release behaviors, and related properties were discussed.

Physical Properties Variability of Zinc Powders Obtained by Electrochemical Method

The aim of this paper is to establish a regulatory change of zinc powders key physicochemical properties with varying electroextraction conditions. It was studied influence zinc concentration, alkali concentration and current density. Quantitative dependencies of zinc powders particle size and specific surface area from mentioned electroextraction parameters are shown. At increasing of zinc concentration, decreasing of NaOH concentration and decreasing of current density of powders particle size growth, correspondingly specific surface area is declined. It is indicated, that electrolytic zinc powders bulk density varies from 0.61 g/cm3 to 0.75 g/cm3 with a decrease of average particle size from 121 μm to 68 μm. In comparison, spherical powders bulk density used in various industries is currently 2.45-2.6 g/cm3. In all experiments, metal zinc content varied in the range of 91.1-92.5%, the rest - ZnO. To a greater extent, this indicator depends on powder washing quality from alkali and storage conditions.

Comparative comminution efficiencies of rotary, stirred and vibrating ball-mills for the production of ultrafine biomass powders

Plant biomass as a substitute for fossil oil is one of the most promising pathways to reducing the environmental impact of human activities. Ultrafine comminution of plant materials can produce ultrafine powders suitable for direct use in advanced-technology applications as an engine, becoming a sustainable powdered biofuel. However, comminution is an extremely energy-intensive process, making it vital for industry to select the most efficient milling device for the biomass. Here, we comprehensively compared the efficiencies of three batch ball mills employable for ultra-fine comminution of plant materials. First, we led a ball motion study to estimate the predominant mechanical stresses generated by each device. Two biomasses with contrasted physical properties were milled using three devices to achieve a target particle size of 20 μm. Milling times and process energy consumption were recorded, and the particle size distributions and specific surface areas of the ground powders were measured. The balls mills were then compared based on several indicators of energy efficiency, productivity and processing speed. The results show that the energy input is better utilized in mills that work by attrition or by combined impact and attrition.

TiO2/AC Composites for Adsorption-Photocatalytic of Methyl Orange

Herein, the adsorption-photocatalytic performance of composite titanium dioxide (TiO2) and Activated Carbon (AC) to decompose methyl orange was investigated systematically. This work demonstrated the synthesis of TiO2/AC composite via the sol-gel method. After getting the composite TiO2/AC under different ratios of AC, the prepared particles were then annealed at 500°C for 2 h. The presence of AC detected by Fourier transform infrared (FTIR) spectra at 1028 nm. Based on Brunauer–Emmett–Teller (BET) analysis, the result showed that the prepared particles specific surface area increased by increasing the AC ratio. The prepared photocatalyst was used to decompose methyl orange under UV light irradiation for 90 minutes. From the photocatalytic performance, the additional AC did not influence the adsorption process significantly under dark conditions. Interestingly, during the irradiation process, methyl orang could be decomposed until 62.5%, which means 15% higher than that of bare TiO2. The present result showed that an additional AC could enhance photocatalytic performance due to its ability as an electron transfer and avoid the recombination process between electrons and holes.

Evaluation of the Anthropogenic Metal Pollution at Osisko Lake: Sediments Characterization for Reclamation Purposes

The anthropogenic pollution of lake ecosystems by human activities (e.g., mining industries) is recognized as a serious issue. The Osisko urban lake located in Rouyn-Noranda (Quebec, Canada) was used partially as a waste disposal facility for many decades, causing a heavy pollution. The main undertakings of this study are (i) assessing the mineralogical and geochemical properties of lake Osisko sediments, and (ii) studying the pollution that occurred within lake water due to the sediments’ reactivity. Water and sediments across the lake were collected in different sensitive locations. Within the sediment samples, two parts were distinguished: a small layer of black vase over grey sediments. The black vase resembled organic matter while the gray sediment seemed close to clean lake sediments. The collected samples were characterized for their physical (particle size distribution, specific gravity and specific surface area), chemical (minor and major elements as well as total sulfur and carbon) and mineralogical (X-ray diffraction and scanning electron microscope) properties. Additionally, the reactivity of sediments was studied using weathering cells to quantify chemical species leaching and their releasing rates. The results showed that the vase was the only contaminated part with high concentrations of sulfur and metals such as copper, zinc and iron. Geochemical data showed that the composite sample and the vase potentially cause contaminated acid drainage if they are exposed to atmospheric conditions. Indeed, the pH values of the leachates from both samples were between 4 and 6, while those corresponding to sediments remained around circumneutral values. Quantitatively, the contaminant release from the tested samples was variable. Indeed, the Fe cumulative concentrations were around 200, 80 and 20 mg/kg for the vase, composite and sediment samples, respectively. Similarly, the Zn cumulative concentrations were around 4500, 4200, and below the detection limit for vase, composite and sediment samples, respectively. The same tendency was observed for Cu, S, and Fe. Thus, sediments within Osisko lake present a risk for water contamination if they are resuspended or dredged out of the lake. Consequently, they should be stabilized before their disposal. The samples’ high Cu contents also offer the possibility of their reprocessing.

Dissolution of copper oxide nanoparticles is controlled by soil solution pH, dissolved organic matter, and particle specific surface area

Dissolution is the primary process affecting the bioavailability and toxicity of nanoscale copper oxide (nano-CuO) to plants and soil organisms. In this study, particle morphology, organic acid, and soil properties were considered to understand the dissolution characteristics of nano-CuO in soil solutions. The results showed that the copper ions (Cu2+) released from spherical nano-CuO (CuO NPs), tubular nano-CuO (CuO NTs), and spherical microsized CuO (CuO MPs) in the ten soil solutions were 26.6–4194.0 μg/L, 4.90–217.1 μg/L, and 10.8–326.0 μg/L, respectively. The concentration of Cu2+ was negatively correlated with the pH of the soil solution and positively correlated with the contents of dissolved organic carbon (DOC), aluminum, and manganese. Multivariate stepwise regression analysis indicated that the dissolution of CuO NPs could be well predicted by pH and DOC contents of the soil solutions. In the GD soil solution (acidic), 4- and 8-fold of the DOC content amendments significantly promoted the dissolution of the three sizes of CuOs, resulting in an increase of Cu2+ 4.55–11.3 and 5.67–16.2 times, respectively. In the CQ soil solution (neutral), 8-fold DOC amendments increase the release of Cu2+ 2.13–16.6 times. While in the SD soil solution (alkaline), promoting effect on the dissolution was only observed for nano-CuOs, with Cu2+ elevated by factors of 1.56–4.64 and 1.38–4.48. The amendments of Al3+ and Mn2+ in soil solution increased the amounts of Cu2+ 1.13–4.80 and 1.02–1.46 times in the GD soil solution. In comparison, no significant promoting effects were observed in CQ and SD soil solutions due to their stronger buffering capacities. These findings offer insight into the dissolution behavior of nano-CuOs in soils and be helpful to evaluate their environmental risks.

Dietary fibers fractionated from gardenia (Gardenia jasminoides Ellis) husk: structure and in vitro hypoglycemic effect.

Gardenia (Gardenia jasminoides Ellis) husk rich in dietary fiber is a byproduct of fructus processing, and commonly discarded as waste. The husk was fractionated by sequential extraction into four fractions: water-soluble fiber (W-SF), acid-soluble fiber (Ac-SF), alkali-soluble fiber (Al-SF) and insoluble residue fiber (IRF). The aim of this study was to investigate the differences in structure and in vitro hypoglycemic effect of these fibers. Monosaccharide composition and Fourier transform infrared spectra showed that the major component might be pectin for W-SF and Ac-SF, xylan as well as pectin for Al-SF and cellulose for IRF. These fibers offered excellent water-holding capacity and swelling capacity, except that IRF was only slightly swellable in water. W-SF exhibited significantly higher capacities to adsorb glucose (2.408 mmol g-1 at a glucose concentration of 200 mmol L-1 ) and inhibit α-amylase activity (29.48-49.45% inhibition rate at a concentration of 4-8mg mL-1 ), probably caused by the higher viscosity and hydration properties; while Ac-SF, Al-SF and IRF (especially Al-SF) were more effective in retarding the glucose diffusion across a dialysis membrane (34.97-41.67% at 20-30min), which might be attributed to particle size and specific surface area. All the fibers could quench the intrinsic fluorescence of α-amylase to some degree. Dietary fiber from gardenia husk, especially W-SF, can be used as a potential hypoglycemic ingredient in diabetic functional foods. © 2020 Society of Chemical Industry.

Influence of 80-mesh Traditional Chinese Medicine Particle Stack Thickness on Percolation Performance

In order to research the influence of 80-mesh traditional Chinese medicine particle characteristics and particle stack thickness on percolation performance, wire screen was used to carry out filtration by the vibratory action of oscillator, screen No. and screen pore size were recorded and weight of screen residue was measured, so as to calculate average distribution density of particles, distribution function of particle size, form factor and specific surface area of particles. Percolation pressure drop was utilized as the index to evaluate percolation performance. Ethanol solution at 20°C with volumetric concentration of 47% was selected as percolation solution to measure and calculate the percolation pressure drop when ethanol solution flowed through 100mm, 150mm, 180mm, 250mm and 300mm 80-mesh particle layer. The results showed that percolation pressure drop is proportional to particle stack thickness, and it is high relatively due to the small size of 80-mesh particle, which shall result in high energy consumption of percolation system.

Influence of the specific surface area of Stöber silica additives on the electrochemical properties of negative electrodes in lead-acid batteries

The surface area of carbon additives has been described as a key property for the enhancement of cycling stability and dynamic charge acceptance (DCA) of negative lead-acid electrodes. However, it is still uncertain if similar performance enhancing effects can be achieved by other inorganic additives of similar structure, or if the electrochemical activity of carbon additives is mandatory for the enhancing effects. In order to elucidate the importance of structure and electrochemical activity of high DCA additives, Stöber silica with tailorable particle size and specific external surface area were prepared and incorporated into negative lead-acid electrodes, combined with the addition of carbon black to ensure high cycling stability. The properties and electrical performance of the negative active material were investigated by electrical tests in 2 V laboratory cells and different physical characterization methods. The overall electrochemical activity in terms of hydrogen evolution and double-layer capacitance was not affected by the silica additive and therefore is also independent of the external surface area. In addition, the silica particles led to a slightly reduced, though steady, mass utilization and discharge capacity. Finally the DCA could not be improved by the Stöber silica additives, which excludes Stöber silica as high DCA additive. In addition, since the DCA performance has not been increased, despite the broad specific surface area range of the additive particles utilized, this study provides a clear indication that the performance enhancement observed with carbon additives also relies on their electrical conductivity.