Ag/PMMA nanocomposites were successfully synthesized by in-situ technique. Transmission electron microscopy (TEM) images show that the particles are spherical in shape and their sizes are dependent on temperature. The smallest particle achieved high stability as indicated from Zeta sizer analysis. The red shift of surface plasmon resonance (SPR) indicated the increases of particle sizes. X-ray diffraction (XRD) patterns exhibit a two-phase (crystalline and amorphous) structure of Ag/PMMA nanocomposites. The complexation of Ag/PMMA nanocomposites was confirmed using Raman spectroscopy. Fourier transform infrared spectroscopy spectra confirmed that the bonding was dominantly influenced by the PMMA and DMF solution. Finally, thermogravimetric analysis (TGA) results indicate that the total weight loss increases as the temperature increases.
Physicochemical properties of threadfin bream surimi with different levels of polydextrose (3%, 6%, 9% and 12%), raw surimi, raw surimi with addition sodium tripolyphosphate and commercial surimi (sucrose) during 6 months of frozen storage were investigated. The analyses included the measurement of Ca(2+)-ATPase, sulfhydryl contents, protein solubility, sodium dodecyl sulfate polyacrylamide gel electrophoresis, differential scanning calorimetry and scanning electron microscopy. The Ca(2+)-ATPase, sulfhydryl content and protein solubility levels added with 3%, 6%, 9% and 12% polydextrose can be maintained until the 6 months of storage by 47.33%, 41.60% and 51.41%, respectively. Differential scanning calorimetry showed decreases in thermal stabilization of myosin with regard to transition termperature. Analysis by scanning electron microscopy demonstrated that the number of pores formed was increased after storage. This study suggested that surimi stored with the polydextrose as a cryoprotectant was able to maintain physicochemical of surimi better compared to raw surimi with no additives or raw surimi with sodium tripolyphosphate.
New polyurethane (PU) nanocomposites were prepared from a dispersion of 0 - 5% montmorillonite (MMT) clay with isocyanate and soya oil polyol that was synthesized via transesterification of triglycerides to reduce petroleum dependence. FT-IR spectra indicate the presence of hydrogen bonding between nanoclay and the polymer matrix, whereas the exfoliated structure of clay layers was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Optical microscopy, mechanical and thermal analyses were done to investigate significant improvement of the nanocomposites. The results showed PU-3% nanoclay (NC) showed optimum results in mechanical properties such as tensile and flexural strength but the lowest in impact strength.
The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet.
Although ultrafiltration (UF) membranes are applicable in wastewater and water treatment, most UF membranes are hydrophobic and susceptible to severe fouling by natural organic matter. In this work, polysulfone (PSf) membrane was blended with silicaluminophosphate (SAPO) nanoparticles, SAPO-34, to study the effect of SAPO-34 incorporation in humic acid (HA) fouling mitigation. The casting solution was prepared by blending 5-20 wt% of SAPO-34 nanoparticles into the mixture of PSf, 1-methyl-2-pyrrolidinone and polyvinyl alcohol at 75 °C. All membrane samples were then prepared using the phase inversion method. Blending SAPO-34 zeolite into PSf membranes caused augmentation in surface hydrophilicity and pore size, leading to higher water permeation. In the HA filtration test, mixed matrix membranes (MMMs) with SAPO-34 zeolite showed reduced HA fouling initiated from pore blocking. The MMM with 20 wt% SAPO-34 loading exhibited the highest increment of water permeation (83%) and maintained about 75% of permeate flux after 2.5 h. However, the SAPO-34 fillers agglomerated in the PSf matrix and induced macrovoid formation on the membrane surface when excessive zeolite was added.
Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi(μ2-O2CCF3)4(THF)3(μ3-O)]2 (1), which was isolated in quantitative yield from the reaction of tetraacetatolead(IV), tetrabutoxytitanium(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex 1 has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, (1)H and (19)F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from 1 by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV-visible spectrophotometry.
Wilting, especially of the leaves, was observed as an initial symptom of arsenate [As(V)] to Ludwigia octovalvis (Jacq.) P. H. Raven. The plants tolerated As(V) levels of 39 mg kg⁻¹ for as long as 35 days of exposure. After 91 days, the maximum concentration of As uptake in the plant occurred at As(V) concentration of 65 mg kg⁻¹ while As concentration in the stems, roots and leaves were 6139.9 ± 829.5, 1284.5 ± 242.9 and 1126.1 ± 117.2 mg kg⁻¹, respectively. In conclusion, As(V) could cause toxic effects in L. octovalvis and the plants could uptake and accumulate As in plant tissues.
Preparation of chitosan-coated fatty acid liposomes is often restricted by the solubility of chitosan under basic conditions. In this experiment, the preparation of chitosan-coated oleic acid (OA) liposomes using low molecular weight (LMW) chitosan (10 and 25 kDA) was demonstrated. These selected LMW chitosans are water soluble. The coating of the chitosan layer on OA liposomes was confirmed by its microscope images and physicochemical properties, such as zeta potential and the size of the liposomes. The "peeling off" effect on the surface of chitosan-coated OA liposomes was observed in the atomic force microscope images and showed the occurrence of the chitosan layer on the surface of OA liposomes. The size of the chitosan-coated liposomes was at least 20 nm smaller than the OA liposomes, and the increase of zeta potential with the increasing amount of LMW chitosan further confirmed the presence of the surface modification of OA liposomes.
Novel ionophores comprising various hydroxide and amine structures were immobilized onto poly(vinyl chloride) (PVC) matrices, and these were examined to determine Ti(III) selectivity. To predict the selectivity of Ti(III), a PVC membrane was used to investigate the binding of Ti(III) to c-methylcalix[4]resorcinarene (CMCR). The study showed that the chelating ligand, CMCR, was coordinated selectively to Ti(III) at eight coordination sites involving the oxygen atoms at the interface of the membrane/solution. The membrane was prepared, based on CMCR as an ionophore, sodium tetrakis(4-fluorophenyl) borate (NaTFPB) as a lipophilic ionic additive, and dioctylphthalate (DOP) as a plasticizer. The immobilization of the ionophore and surface characterization studies revealed that the performance of CMCR-immobilized PVC was equivalent to that of mobile ionophores in supported liquid membranes (SLMs). The strengths of the ion-ionophore (CMCR-Ti(OH)(OH(2))(5) (2+)) interactions and the role of ionophores on membranes were studied via UV-Vis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and and X-ray diffraction (XRD).
Wood sawdust was converted into a high-quality activated carbon (WSAC) via microwave-induced K(2)CO(3) activation. The operational variables including chemical impregnation ratio, microwave power and irradiation time on the carbon yield and adsorption capability were identified. The surface physical characteristics of WSAC were examined by pore structural analysis, scanning electron microscopy and nitrogen adsorption isotherms. The adsorptive behavior of WSAC was quantified using methylene blue as model dye compound. The best conditions resulted in activated carbon with a monolayer adsorption capacity of 423.17 mg/g and carbon yield of 80.75%. The BET surface area, Langmuir surface area and total pore volume were corresponded to 1496.05 m(2)/g, 2245.53 m(2)/g and 0.864 cm(3)/g, respectively. The findings support the potential to prepare high surface area and mesoporous activated carbon from wood sawdust by microwave assisted chemical activation.
Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.
Thin and transparent films of doped cadmium sulfide (CdS) were obtained on commercial glass substrates by Chemical Bath Deposition (CBD) technique. The films were doped with low concentration of Sn, and annealed in air at 300 °C for 45 min. The morphological characterization of the films with different amounts of dopant was made using SEM and EDAX analysis. Optical properties of the films were evaluated by measuring transmittance using the UV-vis spectrophotometer. A comparison of the results revealed that lower concentration of Sn doping improves transmittance of CdS films and makes them suitable for application as window layer of CdTe/CIGS solar cells.
The application of "green" chemistry rules to nanoscience and nanotechnology is very important in the preparation of various nanomaterials. In this work, we successfully developed an eco-friendly chemistry method for preparing silver nanoparticles (Ag-NPs) in natural polymeric media. The colloidal Ag-NPs were synthesized in an aqueous solution using silver nitrate, gelatin, and glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag-NPs were studied at different reaction times. The ultraviolet-visible (UV-vis) spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The prepared samples were also characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The use of eco-friendly reagents, such as gelatin and glucose, provides green and economic attributes to this work.
Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time.
An enhanced ferromagnetic property, visible light active TiO(2) photocatalyst was successfully synthesized by supporting strontium ferrite (SrFe(12)O(19)) onto TiO(2) doped with nitrogen (N) and compared with N-doped TiO(2). The synthesized catalysts were further characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDS), BET surface area analysis, vibrating sample magnetometer (VSM), X-ray photon spectroscopy (XPS) and visible light spectroscopy analysis for their respective properties. The XRD and EDS revealed the structural and inorganic composition of N-TiO(2) supported on SrFe(12)O(19). The supported N-TiO(2) exhibited a strong ferromagnetic property with tremendous stability against magnetic property losses. It also resulted in reduced band gap (2.8 eV) and better visible light absorption between 400 and 800 nm compared to N-doped TiO(2). The photocatalytic activity was investigated with a recalcitrant phenolic compound namely 2,4-dichlorophenol (2,4-DCP) as a model pollutant under direct bright and diffuse sunlight exposure. A complete degradation of 2,4-DCP was achieved with an initial concentration of 50mg/L for both photocatalysts in 180 min and 270 min respectively under bright sunlight. Similarly the diffuse sunlight study resulted in complete degradation for supported N-TiO(2) and >85% degradation N-TiO(2), respectively. Finally the supported photocatalyst was separated under permanent magnetic field with a mass recovery ≈ 98% for further reuse.
The potential of Mg(x)Co(2-)(x)O(2) as heterogeneous reusable catalyst in transesterification of palm oil to methyl ester was investigated. The catalyst was prepared via co-precipitation of the metal hydroxides at different Mg-Co ratios. Mg(1.7)Co(0.3)O(2) catalyst was more active than Mg(0.3)Co(1.7)O(2) in the transesterification of palm oil with methanol. The catalysts calcined at temperature 300 °C for 4 h resulted in highly active oxides and the highest transesterification of 90% was achieved at methanol/oil molar ratio of 9:1, catalyst loading of 5.00 wt.%, reaction temperature of 150 °C and reaction time of 2 h. The catalyst could easily be removed from reaction mixture, but showed 50% decrease in activity when reused due to leaching of active sites.
Zinc oxide nanoparticles (ZnO-NPs) were synthesized via a solvothermal method in triethanolamine (TEA) media. TEA was utilized as a polymer agent to terminate the growth of ZnO-NPs. The ZnO-NPs were characterized by a number of techniques, including X-ray diffraction analysis, transition electron microscopy, and field emission electron microscopy. The ZnO-NPs prepared by the solvothermal process at 150°C for 18 hours exhibited a hexagonal (wurtzite) structure, with a crystalline size of 33 ± 2 nm, and particle size of 48 ± 7 nm. The results confirm that TEA is a suitable polymer agent to prepare homogenous ZnO-NPs.
Visible-light driven photocatalyst bismuth vanadate (BiVO4) photocatalyst was synthesized by the polyol route using ethylene glycol. The precipitate was washed, dried and calcined at 450 degrees C for 3 hr. The sample was characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), zeta potential, surface area (BET method) and band gap energy via diffuse reflectance spectroscopy (DRS). The synthesized BiVO4 has a monoclinic phase with a surface area of 4.3 m2/g and a band gap energy of 2.46 eV. A majority of the particles were in the range of 90-130 nm as obtained from the particle size distribution histrogram. The efficiency of the sample as a visible-light driven photocatalyst was examined by photodegrading Methylene Blue (MB). The effects of some operational photodegradation parameters such as mass loading, initial dye concentration and pH were also examined. Experimental design methodology was applied by response surface modeling and optimization of the removal of MB. The multivariate experimental design was employed to develop a quadratic model as a functional relationship between the percentage removal of MB and three experimental factors (BiVO4 loading, MB initial concentration and pH). The percentage removal of MB approached 67.21% under optimized conditions. In addition, a satisfactory goodness-of-fit was achieved between the,predictive and the experimental results.
Physical adsorption and photocatalytic reduction of Cr(VI) in magnetic separable beads were investigated. In order to elucidate the kinetics of photocatalytic process, operating parameters such as catalyst dosage and the initial concentration were examined in detail. It was observed that the reduction rate of Cr(VI) increased with an increase in the catalyst loading, as this translated into an increase in the number of available active sites. Critical scrutiny of the percentage of the initial reduction rate versus time at various initial concentration of Cr(VI) revealed that the rate of substrate conversion decreased as the initial concentration increased. The kinetic analysis of the photoreduction showed that the removal of Cr(VI) satisfactory obeyed the pseudo first-order kinetic according to the Langmuir-Hinshelwood (L-H) model and the absorption of Cr(VI) on the magnetic beads surfaces was the controlling step in the entire reduction process. Furthermore, desorption experiments by elution of the loaded gels with sodium hydroxide indicated that the magnetic photocatalyst beads could be reused without significant losses of their initial properties even after 3 adsorption-desorption cycles.
Laser ablation of a silver plate immersed in virgin coconut oil was carried out for fabrication of silver nanoparticles. A Nd:YAG laser at wavelengths of 1064 nm was used for ablation of the plate at different times. The virgin coconut oil allowed formation of nanoparticles with well-dispersed, uniform particle diameters that were stable for a reasonable length of time. The particle sizes and volume fraction of nanoparticles inside the solutions obtained at 15, 30, 45 min ablation times were 4.84, 5.18, 6.33 nm and 1.0 × 10(-8), 1.6 × 10(-8), 2.4 × 10(-8), respectively. The presented method for preparation of silver nanoparticles in virgin coconut oil is environmentally friendly and may be considered a green method.