Further Increase In Concentration Research Articles

Study on phase behavior of compounded system of sodium lauryl gluta-mate and lauramide propyl hydroxysulfobetaine

Abstract As a green and safe amino acid surfactant, sodium lauryl glutamate (SLG) has been favored by researchers. However, SLG has low solubility and its single system is not conducive to its application. Zwitterionic surfactants can increase its solubility by forming mixed micelles and possibly new phase states. In this paper, SLG was combined with lauramide propyl hydroxysulfobetaine (LHSB), and its different states were characterized. The type of phase states were determined and the pseudo-ternary phase diagrams were drawn. It was found that when the concentration of SLG was low and the proportion of SLG was not high, there were a large number of globular micelles in the solution, and rod-like micelles would appear as the concentration increased. As the concentration further increased, the SLG/LHSB system exhibited the characteristic of worm like micelles. With the further increase of concentration, the liquid crystal structures of hexagonal and layered phases were observed.

Effect of heat treatment on charge states, thermophysical and mechanical properties of polypropylene doped with ZrO2 nanoparticles

Charge states, thermophysical and mechanical properties of polypropylene doped with zirconium oxide nanoparticles, and their changes during heat treatment at temperatures 60 °C, 100 °C, and 140 °C are studied. The methods used are thermal stimulated depolarization (TSD), scanning differential calorimetry (SDC), and mechanical life assessment. It is shown that with an increase in the concentration of the filler, the intensity of the TSD peaks increases up to 3 vol.%. A further increase in concentration leads to a decrease in the intensity of the peaks. The activation energy of charge release from traps, temperature of maximum of the peaks, and the magnitude of the accumulated charge in the traps have also maximal value at nanoparticle concentration of 3 vol.%. The study of charge characteristics of the nanocomposite with concentration of 3 vol.% after heat treatment shows that the intensity of TSD peaks, the temperature of peak maxima, and the activation energy of charge release increase with increasing pretreatment temperature. The magnitude of the charge accumulated in traps has a maximal value at treatment temperature of 140 °C owing to the increase in the number of traps. The melting point of the composite is 149.38 °C and shifts to 146.88 °C after heat treatment at 140 °C. It indicates that the high temperature of heat treatment leads to partial destruction of polymer chains, leading to a decrease in the critical melting temperature. The mechanical durability of PP + 3%ZrO2 nanocomposite decreases with increase in pretreatment temperature.

A comparative study on the effects of multi-walled carbon nanotubes and graphene nanoplates incorporated for improved thermal conductivity and dielectric properties of polyvinyl chloride

In the present work, the improvement in the thermal conductivity and dielectric behavior in the frequency range of 0.025–5 MHz of polyvinyl chloride (PVC) films incorporated with graphene nanoplates (GNs) and multi-walled carbon nanotubes (CNTs) were investigated. The neat PVC and PVC composites consisting of different filler ratios of 0.25, 0.5, 0.75, and 1 wt% were synthesized using the casting technique. The increase in the concentration of GNs or CNTs up to 0.75 wt% enhanced the dielectric constant, ac conductivity, q-factor, F-factor, thermal conductivity, and total impedance of PVC composites. The values of the investigated parameters are slightly higher for PVC-CNTs composites compared to PVC-GNs composites. A further increase in concentration to 1 wt% reduces these parameters, but still more than PVC consisting of 0.5 wt% fillers. The mechanism of correlated barrier hopping (CBH) could be successfully used to describe the AC electrical conductivity of both PVC-GNs and PVC-CNTs composites thin films. Furthermore, the glass transition and decomposition temperatures were determined and found to be dependent on the filler ratio and type, and the thermal stability was increased after adding the GNs or CNTs nanofillers. These findings have drawn special attention to developing PVC composites that can be used in various industrial fields including flexible and wearable technologies, power devices, supercapacitors, electric vehicle battery systems, and aerospace components.

ПРОТИВОКОРРОЗИОННАЯ ЗАЩИТА МЕДИ МАСЛЯНЫМИ КОМПОЗИЦИЯМИ С КОМБИНИРОВАННОЙ ДОБАВКОЙ М-531

The use of anti-corrosion protection is necessary to maintain the performance of agricultural machinery and equipment. The effectiveness of oil compositions with the addition of M-531 in relation to copper was studied. The compositions were obtained on the basis of industrial and motor M10G2k (both fresh and used) oils. Their protective ability was studied using gravimetric and electrochemical methods (polarization and impedance) studies. According to the data obtained from corrosion gravimetric tests in 0.5 M NaCl, it was noted that compositions based on M10G2k oil turned out to be the most effective when 5 wt. % of the additive, the protective effectiveness (Z) was 63%, a further increase in concentration led to a slight increase to Z = 65% at 10 wt. % M-531. The data from electrochemical measurements qualitatively confirm the data from gravimetric tests. Differences in the magnitude of protective effectiveness are associated primarily with different times of exposure to an aggressive environment: the duration of the experiment in the first case was 15 minutes, in the second - 14 days. According to the results of polarization measurements, compositions based on MMO were the most effective, already at a content of 5 wt. % additive value Z = 98%, while compositions containing 5 wt. % M-531 in I20-A and M10G2k had Z = 90%. The results of impedance studies showed that the addition of the M-531 inhibitor to MMO, M10G2K and I20-A oils affects the copper impedance hodographs. The inhibitor concentration had a significant effect on the change in Nyquist diagrams. At 3 wt. % M-531, a moderate change in copper plating impedance was observed, indicating that the inhibitor has some protective ability against corrosion, but its effectiveness may not be sufficient to fully protect copper. When the inhibitor concentration increases to 5 - 7 wt. % noticeable increase in the change in impedance indicated that a higher concentration of the M-531 inhibitor helps to improve the protective properties of the copper coating.

Specifications for applying high octane additives to the motor gasoline in hot climate

The article analyzes the use of high-octane additives to motor gasoline used in hot climates. We have studied anti-knock additives as additives to improve the octane number of gasoline. An additive based on alcohols, octane-Booster, was used as such additives. Laboratory studies were carried out on the physicochemical parameters of AI-80 and AI-92 gasoline with the addition of an anti-knock additive. The results of the studies show that when gasoline is used in hot climates, the addition of high-octane components based on alcohols increases the octane number, but at the same time the boiling point of the light fraction of gasoline decreases. With an increase in the percentage of additive, the boiling point of the light fractions reached 58°C. Taking into account all the experimental data obtained, we suggest adding a percentage of this additive of no more than 3%, which shows the optimal octane number and distillation temperature of 10% gasoline for hot climates. With a further increase in concentration to 5%, the octane number increases, but at the same time the distillation temperature of 10% gasoline sharply decreases, which can lead to increased friction losses. When the concentration increased above 5%, the octane number did not change. To ensure optimal engine operating conditions in hot climatic conditions, we suggest ensuring that the boiling point of gasoline at the beginning of distillation is not lower than 40°C ÷ 43°C, and the distillation temperature of 10% gasoline is not lower than 70°C.

Влияние поверхностно-активных веществ на комплексообразование титана (IV) с бромпирогал-лоловым красным

The article presents the investigation results of the effect of nonionic surfactants on the complexation of titanium (IV) with bromopyrogallol red (BPR), a triphenylmethane dye. The optimal formation conditions, properties of complexes, and the effect of various organic solvents on the complexation have also been studied. The absorption spectra and kinetics of the complex formation reaction have been studied for compositions such as BPR-surfactant and Ti-BPR-surfactant. The substances OP-7 and OP-10, which differ by length of oxyethylene chain, have been selected as nonionic surfactants. An increase in the concentration of surfactants does not lead to bathochromic or hypsochromic shifts in the absorption spectra; however, when the concentration of OP-7 reaches 0.07% or OP-10 is up to 0.008%, the the solution absorbance increases. For kinetic dependences, it has been found that in the absence of surfactants the resulting complex does not stabilize for two hours, while with an increase in the concentration of OP-7, the complex forms within 16 minutes and remains stable for a long time. In the presence of OP-10, the complex also stabilizes in 16 minutes and remains stable for an hour at the concentration of 0.008%, with a further increase in concentration, the complex collapses and its absorbance decreases. The presence of organic solvents in the reaction mixture, in particular acetone, practically does not affect the absorbance of the organic reagent solution in any way, but hypochro-mically affects the resulting complex with titanium, which may indicate the penetration of acetone in-to the inner coordination sphere and the destruction of the metal compound with the organic reagent, which is also indicated by precipitation, if the acetone concentration reaches 40%. The calibration curve of Ti-BPR-OP-10 is linear in the concentration range from 0.4×10–5 to 9.6 ×10–5 M, for the Ti-BPR-OP-7 system this interval is (0.4–8.0)×10–5 M. The complexation is hindered by vanadium (V) and aluminum (III) ions. The interfering effect of these ions can be eliminated by introducing ammo-nium citrate and ascorbic acid into the system. Using experimental data and graphical methods – the slope ratio method, the molar ratio method and the isobestic point method – the stoichiometric com-position of the reagents in the complex has been established. In systems with OP-7 and OP-10, there are two forms of titanium complex with BPR: with the 1:2 ratio and, at increased BPR concentration, with the 1:4 ratio. Komar's graphical method has shown that complexes with the 1:4 ratio have the greatest stability, the stability constants for Ti-BPR-OP-10 and Ti-BPR-OP-7 systems in this case are 6×1015 and 2.5×1016, respectively.

Ice recrystallization inhibition and acceleration by cellulose nanocrystals in the presence of anionic and neutral polymers

Understanding mixed stabilizers' ice recrystallization inhibition (IRI) effect is important for ice cream formulation. The IRI effect of cellulose nanocrystals (CNCs) was investigated in the presence of sodium alginate (SA), carboxymethyl cellulose (CMC), polyethylene glycol (PEG), and inulin. Adding low concentrations of SA (≤0.13%) and CMC (≤0.05%) enhanced the IRI effect of CNCs. The enhancement became less at higher concentrations of SA and CMC. Recrystallization was even accelerated with a further increase in concentration of SA (≥0.5%) or CMC (≥0.2%). PEG and inulin had little influence on the IRI effect of CNCs. Rheological analysis of polymer overlap concentration, particle size analysis of CNCs dispersion, and microscopical observation of ice crystals accretion suggested that the dual effects of excluded volume might explain the IRI effect of CNCs in the presence of polymers: (1) adding polymers resulted in the macromolecular crowding, reducing the available volume for CNCs and increasing their effective concentration to interact with ice crystals, and led to an enhanced IRI effect; (2) depletion interaction promoted the aggregation of CNCs and merging of ice crystals, resulting in less enhancement and recrystallization acceleration. Our findings advance our understanding of the IRI effect for mixed stabilizers and are critical to ice cream formulation.

Investigating the selective flotation of auriferous arsenian pyrite from refractory ores using thionocarbamate

Thionocarbamate, specifically modified Isopropyl Ethyl Thionocarbamate (IPETC) is selective in the separation of pyrite from arsenopyrite, following copper activation. In this work, the flotation response of a refractory gold (Au) ore containing arsenic (As) mainly in the form of arsenian pyrite is investigated to reject gold-barren sulphidic phases. The recovery of Au increased with an increase in CuSO4 concentration to 0.3 kg/t, beyond which further increase in concentration yielded no significant recovery. Variations of IPETC concentration between 0.2 and 1.5 kg /t of ore influenced both gold and arsenic recovery. It was surmised that the high collector dosage may have resulted from competitive adsorption between arsenian pyrite and other gangue minerals in the ore. 0.3 kg/t CuSO4 and 1.2 kg/t IPETC concentration at pH 11 gave the best results of 86% Au and 83% As recovery at an Au and As grade of 8.14 g/t and 2436 ppm respectively. LA-ICP-MS analysis of the concentrate showed a positive correlation between gold and arsenic. The technique also revealed arsenic-rich zones in pyrite which was further confirmed by SEM/BSD imaging to be rims of arsenian pyrite encapsulating Au-barren pyrite. MLA mineral maps of concentrates obtained at different times also showed that there is no relationship between the arsenic content of pyrite and the flotation rate. The deportment of arsenic in the rims of pyrite presents a complex mineralogical association which results in a decrease in concentrate grade.

Graphene Quantum Dots Nonmonotonically Influence the Horizontal Transfer of Extracellular Antibiotic Resistance Genes via Bacterial Transformation.

Graphene quantum dots (GQDs) coexist with antibiotic resistance genes (ARGs) in the environment. Whether GQDs influence ARG spread needs investigation, since the resulting development of multidrug-resistant pathogens would threaten human health. This study investigates the effect of GQDs on the horizontal transfer of extracellular ARGs (i.e., transformation, a pivotal way that ARGs spread) mediated by plasmids into competent Escherichia coli cells. GQDs enhance ARG transfer at lower concentrations, which are close to their environmental residual concentrations. However, with further increases in concentration (closer to working concentrations needed for wastewater remediation), the effects of enhancement weaken or even become inhibitory. At lower concentrations, GQDs promote the gene expression related to pore-forming outer membrane proteins and the generation of intracellular reactive oxygen species, thus inducing pore formation and enhancing membrane permeability. GQDs may also act as carriers to transport ARGs into cells. These factors result in enhanced ARG transfer. At higher concentrations, GQD aggregation occurs, and aggregates attach to the cell surface, reducing the effective contact area of recipients for external plasmids. GQDs also form large agglomerates with plasmids and thus hindering ARG entrance. This study could promote the understanding of the GQD-caused ecological risks and benefit their safe application.

The Effect of Phycocyanin Isolated from Arthrospira platensis on the Oxidative Stress in Yeasts

C-phycocyanin, being a component of the photosynthetic apparatus of cyanobacteria, is an effective antioxidant and anti-inflammatory agent and is often used in medical studies. The intracellular effect of C-phycocyanin isolated from cyanobacteria Arthrospira platensis on the levels of the prooxidant-induced oxidative stress and cell death of the aerobic yeast Yarrowia lipolytica is considered. We show that C-phycocyanin accumulated in the yeast cells and had a direct antioxidant effect on the yeast suspension within the concentration range of 10–100 μg/mL and a cytotoxic effect with a further increase in concentration. The effect of C-phycocyanin in the most effective concentration is comparable to the antioxidant effect of the mitochondria-targeted cation SkQ1.

Anomalous Diffusion of Deformable Particles in a Honeycomb Network.

Transport of deformable particles in a honeycomb network is studied numerically. It is shown that the particle deformability has a strong impact on their distribution in the network. For sufficiently soft particles, we observe a short memory behavior from one bifurcation to the next, and the overall behavior consists in a random partition of particles, exhibiting a diffusionlike transport. On the contrary, stiff enough particles undergo a biased distribution whereby they follow a deterministic partition at bifurcations, due to long memory. This leads to a lateral ballistic drift in the network at small concentration and anomalous superdiffusion at larger concentration, even though the network is ordered. A further increase of concentration enhances particle-particle interactions which shorten the memory effect, turning the particle anomalous diffusion into a classical diffusion. We expect the drifting and diffusive regime transition to be generic for deformable particles.

Positive effects of a formulated microbial consortium on the growth and well-being of okra and tomato crops

The impact of microbial consortium (MC) comprising plant development-promoting organisms (PGPMs), for example, Bacillus sp., Enterobacter sp. (bacteria), Aspergillus sp., Penicillium sp. (fungus), and streptomycin sp. (actinomycetes) which are effective on two vegetable crops (okra and tomato). These strains were collected from five geologically isolated soil samples of agricultural fields around Bhubaneswar, Khurda, India (20.65946°N, 86.75409°E) and were biochemically characterized. The promising isolates were confirmed by 16s rRNA sequence. The MC was applied at five different concentrations, viz., 0.2%, 0.5%, 1.0%, 1.5%, and 2.0% (v/v using MS medium) along with a control were included. The combinations of above mentioned PGPMs strains significantly increased shoot height, plant height, leaf length, and leaf width at three-day intervals, and fresh weight, dry weight, and root length at the end of the study period. The results revealed that the protective effect of MC significantly increased all the parameters. The crop growth parameters were confirmed MC was effective when tested against control crops. The MC was more effective with the soil base than without a soil base. Among different concentrations of MC, 0.5% of MC was more effective for all the test crops as compared to other concentrations. So, 0.5% was optimal for microbial colonization to ensure the provision of soil nutrients, as no discernible change in growth parameters was observed to further increase in concentration. Also, a study on microbial and physicochemical parameters of all the treatments of all the crops was recorded. The lab study is a small-scale investigation to confirm the efficacy and the sustainability of MC in with soil and without soil of Odisha. Overall, the study illustrated a healthy biotic (consortium microbes and natural soil microbes) and abiotic (MS medium and soil supplement) interaction is advantageous for crop development and advancement.

Electrical Discharge Machining of Alumina Using Cu-Ag and Cu Mono- and Multi-Layer Coatings and ZnO Powder-Mixed Water Medium

The paper aims to extend the current knowledge on electrical discharge machining of insulating materials, such as cutting ceramics used to produce cutting inserts to machine nickel-based alloys in the aviation and aerospace industries. Aluminum-based ceramics such as Al2O3, AlN, and SiAlON are in the most demand in the industry but present a scientific and technical problem in obtaining sophisticated shapes. One of the existing solutions is electrical discharge machining using assisting techniques. Using assisting Cu-Ag and Cu mono- and multi-layer coatings of 40–120 µm and ZnO powder-mixed deionized water-based medium was proposed for the first time. The developed coatings were subjected to tempering and testing. It was noticed that Ag-adhesive reduced the performance when tempering had a slight effect. The unveiled relationship between the material removal rate, powder concentration, and pulse frequency showed that performance was significantly improved by adding assisting powder up to 0.0032–0.0053 mm3/s for a concentration of 14 g/L and pulse frequency of 2–7 kHz. Further increase in concentration leads to the opposite trend. The most remarkable results corresponded to the pulse duration of 1 µs. The obtained data enlarged the knowledge of texturing insulating cutting ceramics using various powder-mixed deionized water-based mediums.

Magneto-transport properties of YBCO:NaNbO3 (nanoparticles or nanorods) composite samples

In this study, the effect of addition of nanostructures of Sodium niobate (NaNbO3) having different morphology i.e. Nanoparticles (NPs) or Nanorods (NRs) on the magneto-transport properties of Y1Ba2Cu3O7-δ-NaNbO3 nanocomposite are investigated. NaNbO3 nanostructures are synthesized by hydrothermal technique whereas Pristine and NaNbO3 added Y1Ba2Cu3O7-δ (YBCO) samples are synthesized through Solid state reaction route. Superconducting transition in electrical measurement showed increased broadening with the increase in applied magnetic field. This broadening is smaller in YBCO composite samples than pristine YBCO indicating better coupling among superconducting grains in the nanocomposites. The tailing effect in the superconducting transition temperature is due to the flux flow of vortices. Further, the activation energy (Uₒ) estimated from ln(ρ) vs 1/T variation indicated its increased value in the nanocomposite YBCO showing enhanced flux pinning. From the applied magnetic field dependence of Uₒ for pristine YBCO and nanocomposite samples, the presence of planar and point defects was confirmed depending on the applied field value. The upper critical field (HC2(0)) estimated using Ginzburg-Landau (GL) theory indicated enhancement in HC2(0) for the nanocomposite samples, with larger enhancement in NPs added YBCO as compared NRs added YBCO. For 0.5 wt% NaNbO3 NPs added YBCO samples, the highest enhancement of HC2(0) (∼1.2 times) as compared to YBCO and other composite samples was achieved whereas further increase of concentration of NPs or NRs in YBCO compound leads to decrement in HC2(0) which is due to increased agglomeration between superconducting grains.

Effect of Glass Filler Geometry on the Mechanical and Optical Properties of Highly Transparent Polymer Composite.

In this work, we studied the influence of the geometry and degree of filling of glass dispersed particles on the optical and mechanical properties of flexible high-transmission composites, based on thermoplastic polyurethane. Glass spheres, glass flake and milling glass fiber were used as fillers. Studies of mechanical properties have shown that the introduction of any filler leads to a decrease in tensile strength and an increase in the elastic modulus of the composite material, however, with the introduction of glass flakes and milling glass fiber, a significant increase in the yield strength of the material is observed. The optical properties of composites with glass spheres decrease exponentially with an increase in the volume fraction of the filler. With an increase in the concentration of glass flakes and milling glass fiber to 10 vol.%, a sharp decrease in transmission is observed. With a further increase in concentration, the orientation of the filler along the film occurs, due to which the transmission in the visible range increases to values close to those of a pure polymer.

Implications of sand mobilization on stability and rheological properties of carbon dioxide foam and its transport mechanism in unconsolidated sandstone

This study reports the role of sand grain (of varying size: 60–380 μm and concentration: 0–3 wt%) on stability and properties of Pickering carbon dioxide (CO2) foam, which relates to foam transport problem during oil recovery practice in unconsolidated formation. For foams, anionic surfactant (sodium dodecyl sulfate: 0.2 wt%) and single-step silica nanofluid (0.1 wt%, size: 33–38 nm) were used and Pickering foams were prepared by mechanical agitation in the presence of different sand (comprised mainly of quartz with traces of clay), to mimic the effect of grain on foam stability. Interestingly, a varying stability exists in presence of sand. Thus, foam volume increased from 48 ml (without sand) to 58 ml when 1 wt% sand (of size ≈ 60–120 μm) was added while it further reduced to 46 and 40 ml with 2 and 3 wt% sand, respectively. On the contrary, foam stability continuously reduced with increment in sand size (from 60 to 120 to 200–380 μm), indicating unfavorable role of sand size on foam stability. Thus, sand production during oil recovery process is unfavorable for the stability of foam systems. The effect of sand concentration and size on foam properties was validated by interfacial tension and rheological measurements. Interfacial tension between CO2-nanofluid decreased till 1 wt% sand, suggesting favorable role of sand on CO2-nanofluid interaction. Similarly, CO2 foam showed maximum viscosity (72.8 mPa s) at 1 wt% sand (of size ≈ 60–120 μm) while further increase in concentration (>1 wt%) and size (>120 μm) reduced foam viscosity. These foams also exhibited viscoelastic characteristics with presence of both storage and viscous moduli. The solid-like nature of foam was least affected by the increase in deformational strain and foams exhibited dominating storage modulus over the range strain explored. Thus, the observation of this study can be used to optimize foam flooding in sandstone reservoirs which exhibit sand/fines production.

Zeta potential and particle size in dispersions of alumina in 50–50 w/w ethylene glycol-water mixture

HypothesisDispersions of solid particles in glycols and in their mixtures in water have been proposed as promising heat transfer fluids, and the zeta potentials in such systems are often reported. We challenge a popular approach in which high absolute value of zeta potential implies excellent stability in such systems. ExperimentsNanoparticles of alumina were dispersed in 50–50 ethylene glycol-water mixture, and zeta potential and particle size were studied as a function of concentration of various solutes. FindingsAddition of HCl and CTMABr induced positive zeta potentials. A maximum value of about 120 mV was obtained at CTMABr concentration of about 10−5 M, and further increase in the concentration of the surfactant had moderate effect on the zeta potential. A maximum value of about 120 mV was obtained at HCl concentrations of 10−5 - 10−4 M, and further increase in the HCl concentration led to depression of the zeta potential. Addition of NaOH and KOH, and of anionic surfactants induced negative zeta potentials. With NaOH and KOH the maximum negative zeta potential of − 60 mV was obtained at base concentration of about 10−3 M, and increase in the base concentration to 10−2 M had moderate effect on the zeta potential. Negatively charged particles showed substantial aggregation in spite of high negative zeta potentials.

Synergistic influence of tetraethyl orthosilicate crosslinker on mixed matrix hydrogels

Hydrogel is a 3D framework of hydrophilic polymeric material that quickly absorbs and retains a huge amount of water (or other fluid) and offers versatile functionality. A series of unique carboxymethyl cellulose/Xanthan gum/polyvinyl alcohol (CXP) blended hydrogels, containing both the natural and synthetic polymers, were prepared by following the blending and casting approach. The polymers were incorporated through chemical crosslinking by tetraethyl orthosilicate (TEOS). The fabricated hydrogels showed all required features: non-toxicity, biocompatibility, and improved mechanical strength. The addition and variation in TEOS (crosslinker) significantly impacted the key characteristics of CXP hydrogel. The scanning electron microscopy (SEM) images showed the porous structure and indicated that the pore's size and intensity were reduced with the surge in TEOS content. Fourier transform infrared spectroscopy (FTIR) results confirmed the successful incorporation of various polymeric strands through crosslinking by TEOS. The thermogravimetric analysis (TGA) highlighted the greater stability of all the hydrogels over high temperatures. The crosslinked hydrogel displayed higher thermal resilience than the uncross-linked one. The differential thermal analysis (DTA) also confirmed that the addition of TEOS content drastically enhanced the thermal endurance of crosslinked hydrogels in comparison with the neat hydrogel. All the specimens exhibited good swelling ability in distilled water during the swelling studies. This study also reflected that the addition of crosslinker in a limited amount (50 µL) has significantly enhanced the swelling but further increase in concentration hindered the water uptake. The swelling response of blends towards pH revealed low swelling of films in acidic and basic pH, but maximal swelling in neutral media. This unique pH response of hydrogels at neutral pH along with the biocompatibility made them suitable for injectable managed drug carrier.

Improved surface temperature of absorber plate using metallic titanium particles for solar still application

Solar distillation technique by using solar stills is the most feasible and environment friendly way to supply fresh water in arid and remote regions. One of the key challenges in solar distillation is to enhance productivity of solar still. In this study, effect of metallic titanium (Ti) particles has been investigated for surface temperature of solar still absorber to increase the distillate production. Ti particles of various concentrations have been blended with black paint and applied on absorber plate. The morphology of the surface and phase identification of powder received have been studied and verified using SEM and XRD. The characteristics of light absorption were examined using Uv–vis Spectroscopy. Extensive outdoor and indoor testing (using improvised solar simulator) have been carried out to optimize the concentration. The highest temperature of 100.39 °C at 1000 W/m2solar irradiation in indoor conditions has been recorded for 7 wt% Ti specimen in black paint which is 11.87% higher compared to only black paint coated aluminum plate and 54.35% higher than bare aluminum plate. The 7 wt% Ti specimen temperature increased up to 77.58 °C in comparison to the aluminum plate having black paint. Further increase in concentration did not increase surface temperature due to excessive convective heat losses.

Thermal Annealing and Doping Induced Tailoring of Phase and Upconversion Luminescence of NaYF4:Yb Er Microcrystals

ABSTRACT The influence of Mn2+ ion concentration (x = 0–20 mol%) as well as the role of thermal-annealing temperature (400–600°C) on the structural as well as luminescence properties of NaYF4:Yb, Er (Y: 78-x%, Yb: 20%, Er: 2%) microcrystals prepared via a coprecipitation method is investigated. The cubic phase of the as-prepared NaYF4:Yb, Er (Y: 78%, Yb: 20%, Er: 2%) was found to remain intact upon the addition of the Mn2+ ions, but the thermal-annealing elucidates that the phase of the sample depends upon the annealing temperature as well as the Mn2+ ion concentration. Among the Mn2+ ion co-doped samples, 3 mol% doped samples dominant to have a maximum positive influence on the upconversion luminescence of the sample, and a further increase in concentration leads to the concentration-induced quenching of the upconversion luminescence. Moreover, the enhancement factor of green (), as well as red () emission, depend upon the annealing temperature, with a maximum enhancement factor of 5 and 3.12 times for the sample annealed at 400°C, 8.6 and 7.25 times for the sample annealed at 500°C, and 6 and 4 times for the sample annealed at 600°C, as compared to Mn2+ ion undoped samples. The maximum emission strength for the green as well as red is observed for the sample annealed at 600°C and co-doped with 3 mol Mn2+ ions. The laser power-dependent study on all the samples shows that the upconversion process is a multi-photon process, predominantly a two-photon process.