Laser Diffraction Particle Size Analyzer Research Articles

Fractal features of sandy soil particle-size distributions during the rangeland desertification process on the eastern Qinghai-Tibet Plateau

Fractal theory has been frequently applied to quantify soil particle-size distributions (PSDs) and evaluate soil degradation. Eolian desertification occurring on the eastern Qinghai-Tibet Plateau is threatening the ecological environment. It is essential to investigate the desertification process by adopting the concept of space as a substitute for time. Here, the fractal features of soil PSDs and their relationships with selected soil properties and wind erosion and deposition were studied. The tested soil samples were collected from rangelands with four different degrees of desertification (light, medium, severe, and extremely severe). Soil particle sizes were measured by a laser diffraction particle-size analyzer. Soil moisture and soil bulk density were determined by the soil weight difference before and after oven-drying for 8 h. Soil organic carbon was determined by the K2Cr2O7-H2SO4 oxidation method and soil total nitrogen was analyzed using the Kjeldahl digestion procedure. Wind tunnel experiments were conducted to simulate wind erosion and deposition during the desertification process. Values of the fractal dimension of soil PSDs were calculated using the volume-based fractal model. ANOVA with an LSD test and Pearson correlation analysis were used to analyze whether different parameters used in the fractal model influenced the results of the fractal dimensions and were reasonable to be applied. Different parameters, including the arithmetic mean size and the upper sieve size of two successive sieve sizes, values of Rmin, and the number of data points used in the fractal model, rarely influenced the results of the fractal dimensions (p > 0.05). The D values showed a significantly positive correlation with the clay and silt contents and a strong negative correlation with the sand contents. Along the degrees of desertification from light to extremely severe, the contents of clay, silt, and very fine sand decreased while the fine sand contents increased, and the D values decreased accordingly. Rangelands with heavier desertification and lower D values were more easily exposed to wind erosion, relating to the further loss of soil organic carbon, soil total nitrogen, and soil moisture and increased soil bulk density. The soil depth could affect soil PSDs and the selected soil properties of rangelands under light and medium degrees of desertification but rarely influenced those of severely and extremely severely desertified lands. Different parameters, including the arithmetic mean size, the upper sieve size, values of Rmin, and the number of data points used in the fractal model, had no impacts on the results of the fractal dimensions, and were reasonable to be applied. We suggest the fractal dimension as an effective indicator to evaluate soil environment changes induced by desertification.

Physicochemical Properties of Yttria-Stabilized-Zirconia In-Flight Particles during Supersonic Atmospheric Plasma Spray

In order to achieve better knowledge of the thermal barrier coatings (TBCs) by supersonic atmospheric plasma spraying (SAPS) process, an experimental study was carried out to elaborate the physicochemical properties of particles in-flight during the SAPS process. One type of commercially available agglomerated and sintered yttria-stabilized-zirconia (YSZ) powder was injected into the SAPS plasma jet and collected by the shock chilling method. The YSZ particles’ in-flight physicochemical properties during the SAPS process, including melting state, morphology, microstructure, particle size distribution, element composition changes, and phase transformation, have been systematically analyzed. The melting state, morphology, and microstructure of the collected particles were determined by scanning electron microscopy (SEM). The particle size distribution was measured by a laser diffraction particle size analyzer (LDPSA). Element compositions were quantitatively analyzed by an electron probe X-ray microanalyzer (EPMA). Additionally, the X-ray diffraction (XRD) method was used to analyze the phase transformation. The results showed that the original YSZ powder injected into the SAPS plasma jet was quickly heated and melted from the outer layer companied with breakup and collision-coalescence. The outer layer of the collected particles containing roughly hexagonal shaped grains exhibited a surface texture with high sphericity and the inside was dense with a hollow structure. The median particle size had decreased from 45.65 to 42.04 μm. In addition to this, phase transformation took place, and the content of the zirconium (Zr) and yttrium (Y) elements had decreased with the evaporation of ZrO2 and Y2O3.

Effects of flour mean particle size, size distribution and water content on rheological properties of wheat flour doughs

This investigation is focused on the granulometric and rheological analysis of two kinds of wheat flour, i.e. type 0 and type 00. The granulometric analysis was carried out using a laser diffraction particle size analyzer. The particle size distribution of the type 0 and 00 flours, expressed as the mass median diameter (D(v,0.5)), was 80.922 µm and 71.686 µm, respectively. The rheological characterization of physical mixtures of wheat flour and water was carried out by means of small deformation dynamic oscillatory measurements. The rheological measurements evidenced a different behavior of the two samples of flour when they were mixed with water. Namely, the progressive addition of water to the type 0 wheat flour favored a decrease of G′ and G″ values, emphasizing that the dough becomes less full-bodied, while its structure remains unmodified; in fact, the phase-angle was not influenced by the water content. On the contrary, the type 00 wheat flour mixed with increased water content provided a dough characterized by lower elastic and viscous moduli, even though the behavior of the phase angle progressively varied. The different results may be due to the different particle size distribution of the flour and the different percentage of gluten present in each. Thanks to this parallel study of the particle size distribution of flours and the rheological behavior of the derived doughs, new food preparation procedures and new research on adulteration in the bread production can be designed.

HYDROXYAPATITE - CARBON NANOTUBE COMPOSITES FOR DRUG DELIVERY APPLICATIONS

Abstract The aim of this study was the synthesis of composites containing hydroxyapatite (Hap) or silicon substituted hydroxyapatite (HapSi), carboxyl functionalized carbon nanotubes (fMWCNT) and gelatin (G) in different ratios. Ibuprofen (IBU) was chosen as a model drug for the formulation of extended-release dosage forms. The obtained composites were characterized using X-ray diffraction, laser diffraction particle size analyzer, Brunauer-Emmett-Teller surface area measurements, transmission electron microscopy and Fourier transformed infrared spectroscopy. IBU adsorption and desorption was monitored by UV-VIS spectroscopy. The obtained results revealed that composites containing three components exhibit higher adsorption efficiency (Hap-fMWCNT-20G - 82.7% and HapSi-fMWCNT-20G - 84.6%) and extended-release of IBU, due to the chemical bonds between the carboxyl groups of IBU and the functional groups on the composite surface. The adsorption capacity of Hap composites is important for dental or orthopedic implants, the anti-inflammatory substances being adsorbed on their surface; but the adsorption capacity also enhances new bone formation (osteosynthesis) around the implants. These composites are thus attractive materials to be used in bone tissue engineering and drug delivery systems.

Dry amorphisation of mangiferin, a poorly water-soluble compound, using mesoporous silica

Mangiferin, a poorly water soluble compound, was processed via a dry amorphisation technique (ball milling) in combination with mesoporous silica to enhance the solubility of mangiferin.The amorphous samples were prepared by mixing 1:1 (w/w) Syloid® XDP 3050 silica-mangiferin mixtures using a planetary mono mill at different milling speeds and milling times according to a 32 full factorial experimental design. The prepared samples were characterized for dissolution profile, particle size distribution using laser diffraction particle size analyzer, thermal characteristics using DSC, crystalline characteristics using XRD and molecular interactions using FTIR and ss-NMR. The samples were tested for stability at stress conditions (40 °C/75%RH) for up to 6 months in open and closed containers. To improve stability of the samples, mixtures of 1:1:2 mangiferin-polymer (Soluplus or HPMC)-silica samples were also prepared and analyzed.Amorphisation of mangiferin is possible using dry amorphisation by ball milling with mesoporous silica in a short amount of time. The amorphisation rate of the samples improved with the energy input of the milling process. The samples prepared with high energy input resulted in amorphous samples and showed a better stability at the stress conditions for up to 3 months. Solubility of these samples increased from 0.32 to 0.50 mg/ml and the particle size decreased from 35.5 µm to around 7 µm. The spectral analysis suggest presence of interactions between the silica material and the compound. The amorphous stability was improved with addition of polymer, even though the solubility of the samples was lower.

Phenoxy herbicides’ interactions with river bottom sediments

MCPA (2-methyl-4-chlorophenoxy acetic acid) and 2,4-D (2,4-dichlorophenoxy acetic acid) have a relatively high water solubility (> 20,000 mg L−1 at 20 °C) and a few studies have examined the affinity of these herbicides for river sediments. The aim of this study was to evaluate whether the concentrations of MCPA and 2,4-D quantified in bottom sediments were associated with the characteristics and herbicide sorption-desorption parameters determined for these sediments. Sixty surface bottom sediments samples (15 cm3) and water column samples (1 L) were collected from 12 sampling sites distributed across selected rivers in a prairie province of Canada, with each site being sampled four to seven times during the summer 2016. The concentrations of MCPA and 2,4-D in the sediment and water column samples were quantified by a gas chromatography coupled to triple quadrupole mass spectrometry. Sediment characteristics included determinations of the organic carbon content (OC), the percentages of sand, silt, and clay by the pipette method, as well as detailed particle size distributions (PSD) as determined using a laser diffraction particle size analyzer. Sorption of 2,4-D and MCPA by sediments was determined using standard batch equilibrium method. Sediments with larger OC contents had relatively larger sorption and smaller desorption when their unimodal PSD had a narrow range (1 to 60 μm), but relatively smaller sorption and larger desorption when their unimodal PSD had a broader range (1 to 1000 μm) thus coarser particle sizes. Sediments with smaller OC contents always had relatively smaller sorption and larger desorption. The detection frequencies and concentrations in sediments were substantially greater for MCPA than 2,4-D even though batch-equilibrium experiments showed that sediments sorbed significantly less MCPA than 2,4-D. Neither MCPA nor 2,4-D concentrations detected in sediments were significantly correlated with sediment properties or their sorption-desorption characteristics. However, the detection frequencies and concentrations in water column samples were also substantially greater for MCPA than 2,4-D. Relatively to 2,4-D, MCPA was more frequently detected in the sediments and in greater concentrations because the more frequent presence of MCPA in the water column allowed for greater opportunities for MCPA to partition to sediments. Thus, the water column loadings of MCPA and 2,4-D, and not sediment characteristics, are the driving force for determining their frequency and concentrations in sediments.

Fabrication and characterization of mullite ceramic hollow fiber membrane from natural occurring ball clay

This work aims to study the physico-chemical and permeation properties of ceramic hollow fiber microfiltration (MF) membranes. Ball clay from Perak, Malaysia was used as an alternative starting material for membrane preparation. The membranes were prepared at various solid loadings (37.5 to 50 wt%) and sintering temperatures (1150 to 1300 °C) via phase inversion-based extrusion/sintering method. Prior to membrane fabrication, the as-received ball clay underwent pre-treatment and was characterized using thermal gravimetric analysis (TGA), laser diffraction particle size analyzer (Metasizer 3000), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Sintered hollow fiber membranes were characterized in terms of crystalline phase using thin-film XRD, surface morphology via scanning electron microscope (SEM), mechanical property using 3-point (3p) method, wall thickness, porosity, pore size distribution and permeation property. XRD patterns show that the ball clay contains 85.9% kaolinite, 9.5% illite, 3.6% quartz and 1% maghemite. After sintering, the major phase of the hollow fiber membranes transformed into mullite (91 to 94%) with minor traces of quartz. The membranes' properties strongly depend on both solid loading and sintering temperature. Moreover, when the hollow fiber membrane with solid loading of 47.5 wt% was sintered at 1250 °C, its mechanical strength (55.8 ± 5.8 MPa) was comparable to that of purity-based ceramic hollow fiber membranes. The membrane has an average porosity and pore size of about 50.5 ± 2.1% and 0.61 μm, respectively, which are within microfiltration range, and has an average pure water flux of 1286 ± 181 L/m2.hr. Compared with its high purity metal oxide ceramic counterparts, this alternative ball clay-based hollow fiber membrane can be sintered at lower sintering temperature while exhibiting comparable mechanical strength and water flux.

Effects of forced-to-exhaust ratio of air volume on dust control of wall-attached swirling ventilation for mechanized excavation face

Wall-attached swirling ventilation is a new type of ventilation for the mechanized excavation face. The dust control effect of the wall-attached swirling ventilation is affected by the forced-to-exhaust air volume ratio. In order to investigate the influence of the air volume ratio on the dust control effect of mechanized excavation face, an experimental model of the wall-attachment swirling ventilation for mechanized excavation face was developed as a reduced scale representation of the D04 mechanized excavation face in Dong Huai Coal Mine of Guangxi Baise Baikuang Group Co., Ltd. Based on this model, the airflow field and dust control of mechanized excavation face at different forced-to-exhaust ratios was analyzed using the study equipment including particle image velocimetry (PIV) system, FCC-25 explosion-proof dust sampler, LS 13320 laser diffraction particle size analyzer, and etc. The analysis results showed that the air velocity at the front end of air supply tube in the wall-attached swirling ventilation was small, the disturbance to the dust production at the heading end by the air flow was weak, and the dust dispersion ability was weak at the front end. In the wall-attached swirling ventilation, both radial air curtain and axial air curtain were generated and pointing to heading end. The cooperation effect of both air curtains controlled dust in the heading area. Thus the operating area for the driver was kept clean and fresh when wall-attached swirling ventilation was running, which ensured a healthy working environment for the roadheader driver. The dust control effect of wall swirling ventilation depended on not only axial air curtain but also radial air curtain. If the forced-to-exhaust ratio was increased, on one hand, the disturbance on the flow field was larger and the intensity of the axial air curtain in the heading end area was weaker; on the other hand, the intensity of the radial air curtain and the dust separation ability were enhanced. When the forced-to-exhaust ratio was 0.8, the wall-attached swirling showed the best dust control effect, the concentration of both the full dust and the respiratory dust around the driver was the lowest, and the separation efficiencies for the full dust and respiratory dust were the highest, which were 93.64% and 98.18%, respectively.

Microstructure and Vickers hardness of mechanically alloyed and spark plasma sintered Ti-2Zn-22Si-11B and Ti-6Zn-22Si-11B alloys

This work reports on effect of zinc and milling time on microstructure and Vickers hardness of mechanically alloyed and spark plasma sintered (66,7-x)Ti-xZn-22,2Si-11,1B alloys (at.-%, with x = 2 and 6 at.-%). Ball milling at different times (20, 60, 180 and 300 min) was performed under argon atmosphere in a planetary ball mill from these elemental powder mixtures. Cylinder bodies with 10 mm diameter were consolidated by spark plasma sintering (1100 °C, 12 min, 20 MPa) under argon atmosphere. As-milled powders and sintered Ti-Zn-Si-B samples were evaluated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, laser diffraction particle size analysis, and Vickers hardness tests. It was noted a similar behavior during ball milling of Ti-Zn-Si-B powder mixtures. Only the α-Ti and Si peaks were indexed in XRD patterns of Ti-Zn-Si-B powders milled for 300 min. Rietveld refining indicated that the amount of amorphous structures has increased during milling up to 300 min, which was more pronounced for the Ti-6Zn-22Si-11B powders. The particle sizes of the Ti-2Zn-22Si-11B and Ti-6Zn-22Si-11B powder mixtures increased during milling from 94 (20 min) to 156 (300 min) μm and from 101 (20 min) to 136 (300 min) μm, respectively. Coherently, the average specific surface area of powder particles was continuously reduced during milling. Despite the adopted parameters, the SPS process produced dense Ti-xZn-22Si-11B (x = 2 and 6 at.-%) alloys with 98% from their theoretical specific mass. Regardless of milling time, the Ti6Si2B formation was inhibited in microstructure of the spark plasma sintered Ti-6Zn-22Si-11B alloy previously milled for longer times. EDS analysis indicated that the Ti6Si2B phase dissolved close to 1.8 at.-% Zn. Beside the TiB and Ti5Si3, the Ti2Zn and Ti3Zn (not explored) phases were also found in microstructure of sintered Ti-Zn-Si-B alloys. The Ti-2Zn-22Si-11B alloy presented average Vickers hardness values higher than 1050 HV whereas the Ti-6Zn-22Si-11B alloy varied between 970 and 1036 HV, which could be associated with the Ti6Si2B formation.

Preparation of hollow glass microspheres@ZnSxSe1−x or copper-/indium-co-doped ZnSxSe1−x composite color pigments with enhanced near-infrared reflectance

To improve the near-infrared (NIR) solar reflectance of ZnSxSe1−x or copper-/indium-co-doped ZnSxSe1−x (ZnSxSe1−x:Cu/In) pigment with various colors, hollow glass microspheres (HGMs)@ZnSxSe1−x or ZnSxSe1−x:Cu/In composite pigments with a litchis-like core-shell structure were prepared with HGMs dispersed and surface-corroded in an alkali-solution under ultrasound and ZnSxSe1−x or ZnSxSe1−x:Cu/In particles deposited on HGMs surface via in-situ co-precipitation and subsequent sintering. The structure, particle size, morphology, color properties and thermal performance of the composite pigments were investigated by X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), laser diffraction particle size analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), nitrogen gas adsorption method (BET), ultraviolet-visible-near-infrared (UV-VIS-NIR) spectroscopy and infrared irradiation image analysis. The results show that ultrasound can promote the corrosion of HGMs surface in alkali solution and form a mesh-pore structure, thus providing some heterogeneous nucleation sites on HGMs surface and favoring the nucleation of pigment precursors on HGMs surface in subsequent in-situ co-precipitation reaction. Compared to ZnSxSe1−x or ZnSxSe1−x:Cu/In pigments, HGMs@ZnSxSe1−x or ZnSxSe1−x:Cu/In composite pigments have a higher solar reflectance since the multiple layer reflections occur at the interface between the pigment particles and HGMs, thus leading to a better heat-reflective property. The NIR solar reflectance of HGMs@ZnSxSe1−x or ZnSxSe1−x:Cu/In composite pigments is 90.61 ± 0.052% or 73.13 ± 0.046%. The surface temperature of aluminum plate coated with HGMs@ZnSxSe1−x composite yellow pigment is 3.4 ± 0.2 °C or 9.6 ± 0.2 °C lower than that of aluminum plate coated or uncoated with ZnSxSe1−x pigment. This approach may shed a light on a promising composite structure design for high-performance solar reflective ‘cool materials’.

Campano-Maastrichtian paleoenvironment, paleotectonics and sediment provenance of western Anambra Basin, Nigeria: Multi-proxy evidences from the Mamu Formation

This article presents the results of a high-resolution evaluation of the sedimentological, mineralogical, palynofacies, and geochemical aspects of the Mamu Formation aimed at deciphering the sediment provenance, as well as the prevailing paleoenvironmental, paleoclimatic and paleotectonic conditions that occurred during the late Campanian-middle Maastrichtian age in the less studied western section of the Anambra Basin, Nigeria. Four measured sections exposed in Uzebba (composite), Auchi, Okpekpe, and Imiegba were investigated using sedimentological (outcrop studies and laser diffraction particle size analysis), mineralogical (XRD), geochemical (ICP-MS and XRF) and palynofacies techniques. Seven lithofacies were identified and grouped into central basin, marsh, bay, barrier, beach, and washover fan facies association as well as meandering fluvial-tidal channel facies association interpreted as indicative of a tidally influenced wave dominated estuarine paleoenvironment. In addition, mineralogical and palynofacies characterization revealed the heterogeneous nature of the dark mudstone lithofacies, varying from a more proximal low salinity phytoclast and quartz dominated marsh and bay mudstones to a more distal higher salinity palynomorph and clay dominated central basin accumulating deep-water mudstones. Consistent with recent Campano-Maastrichtian paleogeographic and paleoclimatic models we observed a dominance of kaolinite, a high chemical index of alteration above 90%, and a predominantly low index of compositional variability values (<1%), which signifies mineralogical maturity of the sediments due to sediment recycling and intensive chemical weathering under humid tropical paleoclimate. Furthermore, trace and major element discriminant plots revealed a felsic-intermediate provenance for the sediments under passive margin paleotectonic regime, which is in agreement with the regional distribution, geology, and geochemistry of the pre-Santonian rocks and the Precambrian basement rocks in the area.

Optimization of bioactive preservative coatings of starch nanocrystal and ultrasonic extract of sour lemon peel on chicken fillets

Starch nanocrystal (S-NC) was produced after sulfuric acid hydrolysis of potato starch granules and then characterized by laser diffraction particle size analyzer, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Response surface methodology (RSM) was applied to optimize S-NC (2–10%) concentration, sour lemon peel extract (SLPE, 2.5–12.5%) amount, mixing temperature (M-TE, 25–65 °C) and mixing time (M-TI,15–75 min) in the preparation of bioactive coating solutions to develop the high-quality chicken fillets during the cold-storage. The optimized conditions for achieving the highest DPPH inhibition percentage (89.14%), antibacterial activity (Staphylococcus aureus, 3.58-mm; Escherichia coli, 3.14-mm; Listeria monocytogenes, 2.31-mm and Salmonella enterica, 2.24-mm) and lightness value (77.82) and the lowest redness (6.69), yellowness (13.21) values and viscosity (27.5 mPa.s) were 4.0% S-NC, 5.62% SLPE, 51.17 °C M-TE and 43.29 min M-TI. Spraying the optimal coating solution on chicken fillets led to a significant improvement in their physicochemical, textural and sensory characteristics compared to the control during 12-day cold-storage.

Studies on sorption of bifenthrin and diazinon insecticides on molecularly imprinted polymers

Synthesis and characterization of polymeric matrices for molecular recognition of pesticides are presented. For their preparation, methacrylic acid as a functional monomer and ethylene glycol dimethacrylate as a cross‐linking agent were used. As template molecules, diazinon and bifenthrin were applied. Syntheses were carried out in the presence of different porogens. Chemical structures were studied using FTIR‐ATR, elemental analysis, and alkacymetric titration, morphology by laser diffraction particle size analyzer and by particle size, and shape analyzer based on image analysis, whereas porous structure by nitrogen adsorption/desorption method. To study selectivity of the sorbent toward template molecule, breakthrough volumes and sorption kinetics for molecularly imprinted polymers and nonimprinted analogues were determined. Particle sizes of the studied sorbents (expressed as CE diameter) were in the range 40 to 44 μm (except sorbent obtained in the presence of hexane). The chemical composition of all obtained sorbents was close to theoretical one (60.13% C, 7.11% H, 32.77% O). The values of specific surface area of the sorbents were in the range 2 to 338 m2/g.

Lignosulfonate, anionic surfactants and their mixtures influence on water solutions surface tension and zinc concentrate pressure leaching

The formation of elemental sulfur during sulfide concentrate pressure leaching leads to the appearance of sulfur-sulfide granules, which significantly reduces zinc dissolution rate. The solution for this problem was the use of surfactants, which prevents the negative effect of molten sulfur, avoiding the granule formation during leaching. Lignosulfonates (waste from the woodworking industry) are most often used as reagents for sulfide concentrate pressure leaching. Influence of individual and mixtures of surfactants on surface tension of aqueous solutions, zinc extraction and size-grade distribution of cakes after sulfide zinc concentrate pressure leaching. Surface tension of aqueous solutions was analyzed by stalagmometric method. Leaching was performed in titanium autoclave in presence of lignosulfonate, sodium dodecylbenzenesulfonate and sodium dodecylsulfate. Solutions after leaching were analyzed on zinc by atomic absorption spectroscopy. Size-grade analysis of cakes after leaching was carried out by laser diffraction particle size analyzer. In this work, synergetic influence was observed of anionic surfactants and lignosulfonate on decreasing of aqueous solutions surface tension. The best results were obtained when LS-SDBS mixture was used, namely in the range of sodium dodecylbenzenesulfonate concentrations 400-600 mg / l. Usage of combined surfactants allowed to achieve high rates of zinc extraction and optimal particle size of cakes after leaching. At Ls and SDBS using zinc extraction was increased from 77,2 % up to 82,8 %, with the bulk of the cake (96,7%) having a particle size of -150 μm. Combined surfactants usage (lignosulfonate and sodium dodecylbenzenesulfonate) can be recommended for applying at pressure leaching of sulfide zinc concentrates.

Properties of spherical stainless steel powders

The additive technologies are gaining popularity due to the possibility of creating custom products for complex applications in many industries. Spherical metal powders are initial components for metal additive manufacturing. Initial materials are very important part of manufacturing, because their quality has an influence on stability of production process and quality of final product. In this work properties of spherical powders including 304L, 310, 316L and 17-4PH grade were determined using scanning electron microscopy, laser diffraction particle size analysis, reductive melting method and X-ray analysis.

Modification of PCC with agar and its application in papermaking

Modification of filler with polysaccharides such as starch, cellulose and their derivatives by preflocculation is an effective means to overcome the main drawback of mechanical strength decline resulting from filler addition. Agar is a mucilaginous polysaccharide extracted from red algaes and was used to modify precipitated calcium carbonate (PCC) for papermaking in our studies. Results showed that when 0.03% cationic polyacrylamide (CPAM) was used as retention aid, tensile index of handsheets using agar (3%, based on PCC) modified PCC as filler was 29.5% higher than native PCC, whereas filler retention did not change obviously. Optical microscope observation and laser diffraction particle size analysis confirmed that PCC was flocculated and coated by agar after modification. Characterizations of mechanical strength and filler retention of handsheets at different filler content indicated the handsheets can be filled with about 10% more agar modified PCC but to maintain the same strength level.

Stability and thermal conductivity enhancement of aqueous nanofluid based on surfactant-modified TiO2

The surface modified-titania (TiO2) nanoparticles were prepared by hydrothermal treatment by two kinds of surfactants, CTAB and SDS. The produced nanoparticles were characterized by XRD, FESEM/EDS, TEM and FTIR analysis techniques. The surfactant modified-TiO2 nanoparticles were dispersed into distilled water to achieve good dispersion stability and enhanced thermal conductivity. The stability of distilled water based nanofluid was checked by sediment photograph capturing. The nanofluid including modified TiO2 nanofluid with a volume fraction of 1.25% stayed up to two weeks without apparent sedimentation contrary to the unmodified TiO2 nanofluid. The UV-Vis spectral results revealed that the decrease in the concentration rate was only about 12% and 20% in case of CTAB treated-TiO2 and for SDS treated-TiO2, respectively. The results obtained from the Laser diffraction particle size analysis showed the existence of thermodynamically stable clusters. The nanofluids made with CTAB-treated and SDS-treated nanoparticles with volume fraction of 1.25% indicated an improvement in thermal conductivity as 15% and 10%, respectively. The transient thermal conductivity measurement allowed monitoring the stability behavior of the nanofluid.

High Li-ion conductivity of Al-free Li7-3xGaxLa3Zr2O12 solid electrolyte prepared by liquid-phase sintering

Ga-doped Li7La3Zr2O12 (Ga-LLZO) is a promising solid electrolyte because it shows higher Li-ion conductivity than LLZO doped with other cations. In this work, Ga-LLZO was prepared by a conventional solid-state reaction and sintered in ZrO2 crucibles to avoid introducing Al into the samples. The particle size distribution, phase structure, morphology, ionic conductivity, and bulk density of the samples were characterized by laser diffraction particle size analyzer, X-ray diffraction (XRD), scanning electron microscope (SEM), AC impedance, and Archimedes method, respectively. The effects of sintering temperature and dopant content on Li-ion conductivity and density were investigated. As for Al-free Li6.4Ga0.2La3Zr2O12, the Li-ion conductivity and bulk density are improved with the sintering temperature rise. But when the sintering temperature is 1250 °C, the Li-ion conductivity and bulk density decline. As for Al-free Li7-3xGaxLa3Zr2O12, the tetragonal phase disappears completely when x ≥ 0.15. The Li-ion conductivity and bulk density of Al-free Li7-3xGaxLa3Zr2O12 are improved with an increase of x (x ≤ 0.2). The ionic conductivity of Al-free Li7-3xGaxLa3Zr2O12 sintered in the air by liquid-phase sintering is close to Ga-LLZO sintered in dry O2 atmosphere. Li6.4Ga0.2La3Zr2O12 sintered at 1200 °C shows the highest Li-ion conductivity of 1.5 × 10−3 S/cm at 30 °C, and the activation energy is about 0.28 eV.

Experimental study on preparation of lauric acid/microwave-modified diatomite phase change material composites

The main aim of this study is to prepare and characterize PCM/diatomite composites with impregnation method using unmodified and microwave modified diatomite. The effect of microwave modification of diatomite on composites was investigated. In this study, lauric acid (LA) was used as the phase change material and the prepared PCM/diatomite composites were analysed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and laser diffraction particle size analyser. Thermal stability of composites was demonstrated by thermal resistance test. The results show that the composites prepared with microwave-modified diatomite have higher heat capacities than those prepared with unmodified diatomite. According to the DSC analysis, composites with modified diatomite have melting and freezing temperatures of 40.4 and 39.5 °C, respectively. These composites also have the latent heats of melting and freezing of 55.7 and −49.9 J/g, respectively. According to the analysis and thermal resistance test, it was seen that composites were prepared successfully. After the determination of better thermal energy storage properties of microwave-modified diatomite containing composites than unmodified diatomite containing composites, we recommend that these composites can be used for thermal energy storage applications.

Influence of Pygoscelis Penguin Colonies on Cu and Pb Concentrations in Soils on the Ardley Peninsula, Maritime Antarctica

Penguins can bioaccumulate metals, a portion of which can be deposited in the environment through organic remains such as excrement, carcasses, and eggshells. In order to determine Cu and Pb concentrations and their relationship to soil, organic matter and grain size were determined in 27 samples collected in zones without penguins, penguin transit zones, and Adelie (Pygoscelis adeliae), Chinstrap (P. antarctica), and Gentoo penguin (P. papua) colonies on the Ardley Peninsula, Maritime Antarctica. An atomic absorption spectrophotometry analysis was carried out, organic matter was determined by loss on ignition, and grain size was measured with a laser diffraction particle size analyzer. The principal component analysis shows a relationship between the variables Cu, Pb, and grain size and areas with penguin presence. Cu concentrations in soils varied among areas (χ2, 15.707; p = 0.0004), with higher concentrations in transit zones and penguin colonies (142.63 and 140.79 mg/kg, respectively) than in zones without penguins (83.33 mg/kg). Pb concentrations in soils also varied among areas (χ2, 6.5029; p = 0.0387), and were higher in transit zones (5.92 mg/kg) than in the penguin colonies (4.45 mg/kg). Grain size differed significantly among areas (χ2, 13.506; p = 0.0012), with higher values in transit zones (avg. 37.38 μm) than in penguin colonies (avg. 26.93 μm) and zones without penguins (avg. 20.72 μm). Organic matter did not differ significantly among the studied zones (χ2, 2.0882; p = 0.3520). There is a positive correlation between Cu-Pb (Rho, 0.5532; p = 0.0028), Cu-grain size (Rho, 0.4756; p = 0.0130) and Pb-grain size (Rho, 0.4879; p = 0.0098). The presence of penguins increases Cu concentrations in Antarctic soils due to its bioaccumulation and elimination through excrement; however, the presence of penguins has a minor influence on Pb concentration in soil, probably because this metal is stored efficiently in bones, feathers, and eggshells.