Synthesis and Activity of Heterogeneous Pd/Al2O3 and Pd/ZnO Catalysts Prepared from Colloidal Palladium Nanoparticles

Heterogeneous catalysts composed of Pd nanoparticles on zinc oxide (ZnO) and aluminum oxide (Al₂O₃, alumina) were synthesized and tested for catalytic activity. Palladium nanoparticles were synthesized via solution-precipitation methods and deposited on aluminum oxide and zinc oxide supports. The particles were synthesized by decomposing a palladium precursor (Pd(Mes)₂) in a solution of trioctylphosphine [TOP route] or palladium acetate (Pd(OAc)₂) in a solution of octylamine [amine route] at 300 °C. The particles were washed and suspended in hexane, whereupon they were deposited on an oxide powder. Supported nanoparticle powders were subjected to CO oxidation tests to determine catalytic activity. Particle sizes ranged from 2.4 ± 0.4 nm average diameter when prepared using trioctylphosphine to 4 ± 1 nm using the amine route. No significant size change was observed after removal of the surfactant and catalytic testing by CO oxidation. The highest conversion of CO to CO₂ occurred with a calcined sample, indicating that the removal of surfactant increases activity.     

Biosynthesis,characterization and cytotoxic activity of CeO2 nanoparticles

Cerium oxide nanoparticles (CeO₂-NPs) have been biosynthesized using the aqueous extract of aerial parts of Prosopis farcta. This plant contains phenolic compounds that function as reducing and capping agents. Biosynthesized particles have been characterized through the use of UV–vis, PXRD, TEM, FESEM, EDX, Raman and FTIR analysis. The UV–vis spectrum clearly showed absorption peak at 317?nm, which indicated the formation of spherical CeO₂-NPs. It displayed in the FESEM and TEM images that the biosynthesized particles are uniformly and spherically shaped with a size of about 30?nm, while the EDX has clearly shown that only the elements Ce and O are present in the biosynthesized sample. Moreover, the Raman spectrum of synthesized nanoparticles has displayed a Ce-O stretching band at a measurement of 459?cm^?1. The cytotoxic activity of biosynthesized nanoparticles against the HT-29 cancer cell line was studied using the MTT assay. All the concentrations of CeO₂-NPs (0–800?µg/ml) showed non-toxic effects and thus, it can be suggested that these nanoparticles have the potential of being utilized in various fields of medicine, such as drug delivery.     

Comparison of dye degradation potential of biosynthesized copper oxide,manganese dioxide,and silver nanoparticles using <Emphasis Type="Italic">Kalopanax pictus</Emphasis> plant extract

Copper(II) oxide (CuO), manganese dioxide (MnO₂), and silver (Ag) nanoparticles were synthesized using Kalopanax pictus plant extract. The nanoparticle synthesis was monitored using UV-visible spectra. The occurrence of each peak at 368, 404, and 438 nm wavelength indicated the synthesis of CuO, MnO₂, and Ag nanoparticles, respectively. The synthesized nanoparticles were characterized by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Catalytic potentials of the synthesized nanoparticles were compared to degrade two typical acidic and basic dyes (Congo red and Safranin O). The degradation ability of MnO₂ nanoparticles against Congo red was higher than that of Ag and CuO nanoparticles. All three types of nanoparticles showed a similar degradation ability against Safranin O over 80%. This study demonstrates that biologically synthesized nanoparticles using Kalopanax pictus are good agents for degradation of dyes.     

Polyethylene glycol assisted facile sol-gel synthesis of lanthanum oxide nanoparticles: Structural characterizations and photoluminescence studies

In this study, lanthanum oxide nanoparticles (La₂O₃ NPs) synthesised via the facile sol-gel method, using a solution of micro-sized lanthanum oxide powders containing 20% nitric acid and high molecular weight polyethylene glycol (PEG). The as synthesised La₂O₃ NPs were then characterized using X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), energy-dispersive X-ray (EDS) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and photoluminescence (PL) spectroscopy. Our findings indicated that the concentration of PEG strongly influences the particle size and the lattice strain of the La₂O₃ NPs. A single phase hexagonal crystal structure was confirmed via XRD studies with lattice constants, a =?b =?0.3973?nm and c =?0.6129?nm. The average crystallite size and lattice strains estimated were in the range of approximately 25–28?nm and 0.0050–0.0055 respectively. The incremental nature of the crystallinity and lattice strains of the NPs was observed with the subsequent enhancement of PEG-contents, while the average particle size was reduced. The average particle size of La₂O₃ NPs estimated from ESEM imaging was consistent with that obtained from the XRD data. The photoluminescence spectra revealed a strong emission band located at a wavelength of 365?nm (typical green band) for all La₂O₃NPsamples. This is ascribed to the recombination of delocalized electrons around the conduction band with a single charged state of a surface oxygen vacancy.     

Preparation and characterizations of superparamagnetic iron oxide‐embedded poly(2‐hydroxyethyl methacrylate) nanocarriers

The present study aims at formulating a novel multifunctional biocompatible superparamagnetic nanoparticles carrier system with homogeneously dispersed magnetic material in solid polymer matrix of poly(2‐hydroxyethyl methacrylate) (PHEMA). The nanocomposites were designed by modified suspension polymerization of 2‐hydroxyethyl methacrylate followed by in situ coprecipitation of iron oxide inside the nanoparticle matrix yielding magnetic PHEMA (mPHEMA) nanocomposites. The so prepared nanocomposites were characterized by Fourier transform Infrared spectroscopy, X‐ray diffraction technique, Raman spectroscopy, electron diffraction, and energy‐dispersive X‐ray spectroscopy confirming the presence of Fe₃O₄ inside the PHEMA nanoparticles. The magnetization studies of nanocomposites conducted at room temperature using vibrating sample magnetometer suggested for their superparamagnetic nature having saturation magnetization (Ms) of 20 emu/g at applied magnetic field of 5 kOe. Transmission electron microscopy, field‐emission scanning electron microscopy, and dynamic light scattering/zeta potential measurements were also performed which revealed that size of mPHEMA nanocomposites was lying in the range of 60–300 nm having zeta potential of ?93 mV. The nanocomposites showed no toxicity as revealed by cytotoxicity test performed on L‐929 fibroblast by extract method. The results indicated that the prepared superparamagnetic mPHEMA nanocomposites have enormous potential to provide a possible option for magnetically assisted targeted delivery of anticancer drugs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40791.     

Permalloy/alumina soft magnetic composite compacts obtained by reaction of Al-permalloy with Fe2O3 nanoparticles upon spark plasma sintering

Composite sintered soft magnetic materials of permalloy/alumina type have been obtained by reactive spark plasma sintering. The composite compacts have been obtained by sintering of Ni71.25Fe23.75Al5 alloy with 3 and 5% (wt.) Fe₂O₃ nanoparticles. The Ni based alloy with large particles (up to hundreds of μm) have been covered by a thin layer of iron ferric oxide nanoparticles (20–40 nm). The as obtained composite particles have been subjected to sintering process using a homemade installation at 900 °C for 10 min. Upon sintering process several reactions between Ni-based alloy and iron oxide are induced, the main phase resulting from reaction is alumina-Al₂O₃ as it results by X-ray diffraction investigations. According to the scanning electron microscopy and energy dispersive X-ray spectroscopy investigations, alumina forms a matrix embedding the Ni-based particles. The alumina matrix is continuous, but the layer has large variation in width, and offers a high electrical resistivity. A mechanism of formation is proposed for the alumina matrix composite compacts when using Al-permalloy powder and iron oxide. The compacts have been tested in DC and AC for magnetic characteristics.     

Comparative investigation of the formation of polytetrafluoroethylene nanoparticles on different solid substrates through the adsorption of tetrafluoroethylene

The effects of different solid substrates, including carbon nanofibers (CNFs), activated carbon, alumina, silica, molecular sieves, and poly(N‐vinylpyrrolidione) (PVP), were compared for the high‐pressure synthesis of polytetrafluoroethylene [PTFE or (CF₂)_n] nanoparticles via the adsorption of thermally synthesized tetrafluoroethylene (C₂F₄) as the monomer. Scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis (TGA) were used for the characterization of the PTFE nanoparticles on different solid substrates. The results demonstrate that the average diameters of the PTFE nanoparticles were about 90 nm for the CNFs, 130 nm for PVP, 150 nm for alumina, and about 200 nm for silica. Also, TGA showed that the amounts of PTFE nanoparticles synthesized on each solid substrate were 3.53 ± 0.09% for CNFs, 2.31 ± 0.10% for PVP, 2.11 ± 0.12% for silica, and 0.97 ± 0.16% for alumina. Depending on the active surface area and the morphology of nanomaterials, such as CNFs, different capacities were evaluated for each solid support in the formation of the PTFE nanoparticles. The quantities and the size of the synthesized PTFE nanoparticles relied on the characteristics of the solid substrate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rapid biological synthesis of silver nanoparticles using Kalopanax pictus plant extract and their antimicrobial activity

Silver nanoparticles (AgNPs) have promising potential in biomedicine, energy science, optics, and health care applications. We synthesized AgNPs using plant, Kalopanax pictus leaf extract. UV-visible spectrophotometric study showed the characteristic peak for AgNPs at wavelength 430 nm. The optical density at 430 nm increased after addition of plant leaf extract, indicating increase in formation of nanoparticles. Comparative time course analyses for AgNP synthesis carried out at different reaction temperatures (20, 60, and 90 °C) revealed higher reaction rate for K. pictus than Magnolia kobus plant leaf extract, which showed highest AgNP synthesis rate in the previous report. Electron microscopy analyses confirmed the presence of well dispersed AgNPs, predominantly with spherical shapes. In transmission electron microscopy, the particle size decreased with increase in temperature. Electron dispersive X-ray spectroscopy analyses indicated that Ag content increased with increase in reaction temperature. Fourier transform-infrared spectroscopy studies revealed capping of bioorganics from plant to the synthesized AgNPs. The antimicrobial activity of the synthesized AgNPs against Escherichia coli increased with increase in reaction temperature. The observations in this study will prove beneficial in approaching rapid synthesis of AgNPs and their antimicrobial application.     

Thermoluminescence properties of Al doped ZnO nanoparticles

ZnO nanoparticles doped with aluminum (AZO nanoparticles) were investigated using low temperature thermoluminescence (TL) and structural characterization experiments. TL experiments were performed on AZO nanoparticles in the temperature range of 10–300?K. TL curve presented one intensive peak around 123?K and two overlapped peaks to intensive peak around 85 and 150?K for heating rate of 0.1?K/s. Curve fitting and initial rise methods were used to find the activation energies of associated trapping centers. Analyses resulted in the presence of three centers at 0.05, 0.08 and 0.17?eV with peak maximum temperatures (T_m) of 86.2, 121.5 and 147.1?K, respectively. TL experiments were expanded using different heating rates between 0.1?K/s and 0.5?K/s. Behavior of revealed traps was investigated using an experimental technique called as T_m??T_stop method. It was seen that traps are quasi-continuously distributed within the band gap. Structural properties were studied using x-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy experiments.     

Thermal stability of transition alumina nanocrystals with different microstructures

The preparation of well-crystallized boehmite nanoparticles with different morphologies, encompassing from aciculae or rods of 320, 150 and 70?nm of length to platelets of 50?nm in diameter, allowed a comparative study of their respective thermal evolutions as alumina precursors. Static thermal treatments of boehmite nanocrystals at 600, 1000 and 1200?°C and a dynamic, in situ synchrotron study between 100 and 1000?°C revealed that original boehmite microstructures, i.e. size and shape of the nanoparticles, were kept not only in γ-Al₂O₃ but also in transitional aluminas up to 1000?°C. Specifically, at that temperature, acicular samples presented θ-Al₂O₃ structure, while in platelet-like nanoparticles δ-Al₂O₃ was identified. Each precursor morphology favored the respective transition phase, extending the thermal stability range over the limits previously reported in the literature.The described methodology was successfully applied to tailor-make transitional Al₂O₃ nanocrystals with microstructures ranging from fibers and rods to platelets, enhancing their thermal stability and thus their potential applications. Different transition sequences were also reported for the different shapes of nano-boehmite precursors.     

Porous mullite blocks with compositions containing kaolin and alumina waste

In the production of alumina by the Bayer process, the calcination step generates a waste containing ~90% aluminum oxide (Al₂O₃). Due to the high content of this oxide, this waste can be used as a source of alumina in porcelain formulations, especially those used in the synthesis of mullite. The purpose of this study was to produce porous mullite blocks using compositions containing kaolin and alumina waste. The compositions were formulated based on a mullite stoichiometry of 3:2. Heat treatments were carried out in a conventional furnace at temperatures of 1450 to 1500 °C, applying a heating rate of 5 °C/min and a 1-h hold time at the firing temperature threshold. The powders were characterized by means of X-ray fluorescence (XRF); X-ray diffraction (XRD); thermal analysis (TGA-DTA); scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The physic mechanical properties of the test specimens: water absorption, apparent porosity, linear shrinkage and flexural strength were also evaluated. The XRD results revealed the formation of mullite as the major phase. The morphological analysis by SEM revealed typical mullite needles originating from clay minerals. The size of the mullite needles was calculated based on the TEM analysis, which indicated diameters smaller than 400 nm, confirming the nanometric dimensions of the needles. The flexural strength test of the specimens indicated that this parameter ​​tends to increase as the temperature is raised.     

Al2O3 nanoparticles with and without polyoxometalates as reactive sorbents for the removal of sulphur mustard

Nanoparticles of AP–Al₂O₃ (aerogel produced alumina) have been produced by an alkoxide based synthesis involving aluminum powder, methanol, toluene and water. Thus produced alumina nanoparticles were characterized by N₂-BET, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transformed infra-red spectroscopy and thermogravimetry techniques. The data indicated the formation of nanoparticles of alumina in the size range of 2–30 nm with high surface area (375 m²/g) and microporous–mesoporous characteristics. Thereafter, these nanoparticles were impregnated with polyoxometalates and other reactive chemicals, which have already proven to be effective against sulphur mustard (HD). Adsorptive removal kinetics for HD was monitored by GC–FID (gas chromatograph coupled with flame ionization detector) technique and found to be following pseudo first order reaction kinetics. Among polyoxometalates impregnated alumina nanoparticles based novel mesoporous reactive sorbent systems AP–Al₂O₃ impregnated with 9-molybdo-3-vanadophosphoric acid (10%, w/w) was found to be the most reactive with least half life value (214 min). In addition to this, degradation products of sulphur mustard on prepared mesoporous reactive sorbents were identified using GC/MS technique. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of sulphur mustard.     

Preparation and evaluation of poly(2-hydroxyethyl aspartamide)-hexadecylamine-iron oxide for MR imaging of lymph nodes

The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C₁₆-iron oxide (PHEA-C₁₆-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C₁₆-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C₁₆-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C₁₆. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C₁₆-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C₁₆-iron oxide nanoparticles. Therefore, PHEA-C₁₆-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes.     

Fabrication of Uniform Au–Carbon Nanofiber by Two-Step Low Temperature Decomposition

This paper presents a facile and efficient way to prepare carbon nanofibers ornamented with Au nanoparticles (Au/CNFs). Gold nanoparticles were first deposited in the channels of an anodized aluminum oxide (AAO) membrane by thermal decomposition of HAuCl₄ and then carbon nanofibers were produced in the same channels loaded with the Au nanoparticles by decomposition of sucrose at 230 °C. An electron microscopy study revealed that the carbon nanofibers, ~10 nm thick and 6 μm long, were decorated with Au nanoparticles with a diameter of 10 nm. This synthetic route can produce uniform Au nanoparticles on CNF surfaces without using any additional chemicals to modify the AAO channels or the CNF surfaces.     

A green chemistry approach for synthesizing biocompatible gold nanoparticles

Gold nanoparticles (AuNPs) are a fascinating class of nanomaterial that can be used for a wide range of biomedical applications, including bio-imaging, lateral flow assays, environmental detection and purification, data storage, drug delivery, biomarkers, catalysis, chemical sensors, and DNA detection. Biological synthesis of nanoparticles appears to be simple, cost-effective, non-toxic, and easy to use for controlling size, shape, and stability, which is unlike the chemically synthesized nanoparticles. The aim of this study was to synthesize homogeneous AuNPs using pharmaceutically important Ganoderma spp. We developed a simple, non-toxic, and green method for water-soluble AuNP synthesis by treating gold (III) chloride trihydrate (HAuCl₄) with a hot aqueous extract of the Ganoderma spp. mycelia. The formation of biologically synthesized AuNPs (bio-AuNPs) was characterized by ultraviolet (UV)-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the biocompatibility of as-prepared AuNPs was evaluated using a series of assays, such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation (ROS) in human breast cancer cells (MDA-MB-231). The color change of the solution from yellow to reddish pink and strong surface plasmon resonance were observed at 520 nm using UV-visible spectroscopy, and that indicated the formation of AuNPs. DLS analysis revealed the size distribution of AuNPs in liquid solution, and the average size of AuNPs was 20 nm. The size and morphology of AuNPs were investigated using TEM. The biocompatibility effect of as-prepared AuNPs was investigated in MDA-MB-231 breast cancer cells by using various concentrations of AuNPs (10 to 100 μM) for 24 h. Our findings suggest that AuNPs are non-cytotoxic and biocompatible. To the best of our knowledge, this is the first report to describe the synthesis of monodispersed, biocompatible, and soluble AuNPs with an average size of 20 nm using Ganoderma spp. This study opens up new possibilities of using an inexpensive and non-toxic mushroom extract as a reducing and stabilizing agent for the synthesis of size-controlled, large-scale, biocompatible, and monodispersed AuNPs, which may have future diagnostic and therapeutic applications.     

Characterization of Poly(Aminosiloxane) Surface Chemistry on Aluminum Oxide

N-2-aminoethyl-3-aminopropyltrimethoxysilane (AAPS) was shown to react with aluminum oxide powder to form an amine/carbonate salt, as observed by diffuse reflectance infrared spectroscopy (DRIFT) and thermogravimetric analysis with mass spectroscopy (TGA-MS). TGA-MS, together with electron spectroscopy for chemical analysis (ESCA), reveal that the stoichiometric ratio of amine salt to free amine is higher on the surface of aluminum oxide powder than in a comparable neat film. In addition, TGA-MS shows that a nonstoichiometric ratio of CO₂H₂O is evolved upon heating the surface-treated powder (4.5/1), whereas the neat film evolves CO₂/H₂O at a ratio near unity. The high fraction of protonated amines, together with the higher ratio of CO₂/H₂O in the presence of alumina, is consistent with a proposed bonding mechanism which involves carbonate bridging between protonated amines and hydroxyl sites on the aluminum oxide surface.     

Mangrove-mediated synthesis of silver nanoparticles using native Avicennia marina plant extract from southern Iran

The development of eco-friendly and nontoxic processes for the synthesis of nanoparticles is one of the most important discussed issues in nanotechnology science. This study reports the green synthesis of silver nanoparticles (AgNPs) using aqueous extract of leaf, stem, and root of Avicennia marina, the native and dominant mangrove plant in southern Iran. Among the different plant parts, the extract of leaves yielded the maximum synthesis of AgNPs. Synthesized AgNPs were investigated using UV–visible spectrophotometry, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. Absorption spectrum in 420?nm confirmed the synthesis of AgNPs. TEM images revealed that the synthesized AgNPs had the same spherical morphology with a size range between 0 and 75?nm. The distribution size histogram indicated that the most frequent particles were in the range of 10–15?nm and the mean size of nanoparticles was 17.30?nm. The results of SEM image showed nanoparticles with a size range between 15 and 43?nm. XRD pattern indicated the crystalline nature of synthesized nanoparticles. EDS results confirmed the presence of elements like silver, carbon, chlorine, nitrogen, and oxygen in the nanoparticles produced from leaf extract. Silver had the maximum percentage of formation, 51.6%. FTIR indicated the presence of different functional groups such as amines, alcohol, alkanes, phenol, alkyl halides, and aromatic loops in the synthesis process. Green biosynthesis of AgNPs using aqueous extract of native A. marina appears rapid, reliable, nontoxic, and eco-friendly.     

Continuous aluminum oxide-mullite-hafnium oxide composite ceramic fibers with high strength and thermal stability by melt-spinning from polymer precursor

Continuous aluminum oxide-mullite-hafnium oxide (AMH) composite ceramic fibers were obtained by melt-spinning and calcination from polymer precursor that synthesized by hydrolysis of the aluminum isopropoxide, dimethoxydimethylsilane and hafnium alkoxide. Due to the fine diameter of 8–9 µm, small grain size of less than 50 nm and the composite crystal texture, the highest tensile strength of AMH ceramic fibers was 2.01 GPa. And the AMH ceramic fibers presented good thermal stability. The tensile strength retention was 75.48% and 71.49% after heat treatment at 1100 °C and 1200 °C for 0.5 h respectively, and was 61.57% after heat treatment at 1100 °C for 5 h. And the grain size of AMH ceramic fibers after heat treatment was much smaller than that of commercial alumina fibers even when the heat treatment temperature was elevated to 1500 °C, benefited by the grain size inhibition of monoclinic-HfO₂ (m-HfO₂) grains distributed on the boundary of alumina and mullite grains.     

Green chemistry synthesized zinc oxide nanoparticles in Lepidium sativum L. seed extract and evaluation of their anticancer activity in human colorectal cancer cells

In recent years, extensive assessments were performed on metal oxide nanoparticles (MONs) for numerous biomedical implementations. This study aimed to describe a facile, environment-friendly and, green route for the synthesis of Zinc Oxide nanoparticles (ZnO-NPs) by exerting Lepidium sativum L. seed extract as a capping agent and to evaluate their anticancer activities on important human colorectal cancer cell lines, SW480, HT-29 and Caco-2. Characterization of the green chemistry synthesized ZnO-NPs were carried out using UV–visible (UV–Vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscope (FE-SEM) and, energy-dispersive X-ray (EDX) spectroscopy. UV–Visible spectra confirmed the biosynthesis of ZnO-NPs and showed a broad absorption peak at 325–450 nm. Microscopic results revealed the formation of the spherical and hexagonal shaped NPs having average size 36.96 and 44.50 nm. In addition, the XRD data demonstrated the crystalline structure of our green ZnO-NPs. In biological experiments, the outcomes of MTT assay indicated the significant cytotoxic effect of ZnO-NPs against SW480, HT-29 and Caco-2 cancer cells through a dosage reliant mechanism. Moreover, the real-time PCR data revealed the potent capability of ZnO-NPs in inducing apoptosis throughout colon cancer cells through the down-regulation of Bcl-2 gene expression and up-regulation of Bax and p53 genes. Overall, these results suggested the applicability of green fabricated ZnO-NPs from the extract of Lepidium sativum L. as a novel and hopeful therapeutic agent for colorectal cancer treatment.     

Effect of oxygen donor alcohol on nonaqueous precipitation synthesis of alumina powders

Monodispersed alumina powders were prepared via nonaqueous precipitation process using aluminum powders as aluminum source, acetic acid as precipitant. Effect of oxygen donor and solvent alcohol such as methanol, ethanol, isopropanol on the preparation of ultrafine alumina powders and the precursor reaction mechanism have been investigated by XRD, FT-IR, TEM, FE-SEM and performance tests of sintered bodies. The intermolecular condensation of methanol with the catalysis of Lewis acid aluminum methoxide leads to hydrolysis of aluminum methoxide, forming amorphous precipitates, dehydration polycondensation of aluminum hydroxide and resulting in serious agglomeration of precipitates and alumina powders, the worst morphology and properties of sintered body. The pulling electron effect and steric hindrance of isopropyl group make the structure of aluminum isopropoxide overwhelmingly stable and relatively arduous to be replaced by precipitant acetic acid, which results in underdeveloped crystallinity and agglomeration of both precipitates and alumina powders, poor morphology and properties of sintered body. The optimized oxygen donor and solvent alcohol is ethanol. Monodispersed, high crystallinity C₄H₇AlO₇ precipitates and alumina powders can be obtained when ethanol is used as oxygen donor and solvent, and the highest relative density, mechanical properties and the most homogeneous microstructure was obtained. The density, flexural strength, volume resistivity, breakdown voltage and thermal expansion coefficient are 99.1% of TD, 128.0?±?2.2?MPa, 9.8?×?10¹⁶ Ω?cm, 45.2?kV/mm and 7.6?×?10^?6 °C^?1, respectively. Precursor reaction mechanism is deduced that aluminum powders react with oxygen donor alcohol to form aluminum alkoxide with the catalyst iodine, and then react with acetic acid to form crystal C₄H₇AlO₇ precipitates. Nonaqueous precipitation method is expected to become a promising candidate for mass production of alumina powders.