A simple solvothermal reduction route to copper and cuprous oxide

Pure copper nanocrystallites and cuprous oxide nanorods have been synthesized via solvothermal treatment of CuSO₄ or CuSO₄·5H₂O and NaOH in pure ethanol and mixed solution of ethanol and deionized water at 140 °C for 10 h, respectively. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were used to investigate the different morphologies of the as-synthesized products. X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) were applied to characterize the composition and crystal phases of the products. It was proposed that the reducibility of ethanol was influenced by temperature and the addition of deionized water in the formation of different phases, which were realized by carefully controlling the experimental conditions.     

Thermal Conductivity and Viscosity Measurements of Water-Based TiO<Subscript>2</Subscript> Nanofluids

In this study, the thermal conductivity and viscosity of TiO₂ nanoparticles in deionized water were investigated up to a volume fraction of 3% of particles. The nanofluid was prepared by dispersing TiO₂ nanoparticles in deionized water by using ultrasonic equipment. The mean diameter of TiO₂ nanoparticles was 21 nm. While the thermal conductivity of nanofluids has been measured in general using conventional techniques such as the transient hot-wire method, this work presents the application of the 3ω method for measuring the thermal conductivity. The 3ω method was validated by measuring the thermal conductivity of pure fluids (water, methanol, ethanol, and ethylene glycol), yielding accurate values within 2%. Following this validation, the effective thermal conductivity of TiO₂ nanoparticles in deionized water was measured at temperatures of 13 °C, 23 °C, 40 °C, and 55 °C. The experimental results showed that the thermal conductivity increases with an increase of particle volume fraction, and the enhancement was observed to be 7.4% over the base fluid for a nanofluid with 3% volume fraction of TiO₂ nanoparticles at 13 °C. The increase in viscosity with the increase of particle volume fraction was much more than predicted by the Einstein model. From this research, it seems that the increase in the nanofluid viscosity is larger than the enhancement in the thermal conductivity.     

Low-temperature synthesis of uniform Sb2S3 nanorods and its visible-light-driven photocatalytic activities

Antimony sulfide (Sb₂S₃) nanorods with uniform size were prepared by the decomposition of Sb(C₇H₇OCSS)₃ in N,N-dimethylformamide solution at 80 °C. The as-prepared Sb₂S₃ was orthorhombic phase and consisted of nanorods with the typical lengths in the range of 200–500 nm and the average diameter of ca. 30 nm. The photocatalytic experiment by degrading methyl orange in aqueous solution under visible light indicated that the activity of the dispersed Sb₂S₃ nanorods was better than that of Sb₂S₃ superstructures aggregated by nanorods.     

Microwave-assisted preparation of calcium sulfate nanowires

We have successfully developed a new synthetic route for the rapid preparation of calcium sulfate nanowires by thermal transformation of calcium dodecyl sulfate (CDS) in organic solvents of ethylene glycol (EG) and N,N-dimethylformamide (DMF). The products are characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), and determined to be single-phase CaSO₄·0.5H₂O consisting of single-crystalline nanowires with aspect ratio up to about 62. In this method, the different types of organic solvents used have no obvious influences on the morphology, phase, and formation time of the product. The microwave heating can remarkably shorten the reaction time compared with conventional heating methods.     

Initial Salt Screening Procedures for Manufacturing Ibuprofen

The aim of this paper is to design initial salt screening procedures for manufacturing ibuprofen. Salt forms of a pharmaceutical acid racemic (R,S)-(±)-ibuprofen and their “developable” synthetic routes were ferreted out simultaneously through the screening of seven bases of sodium hydroxide, potassium hydroxide, l-arginine, l-histidine, l-lysine, diethanolamine, and tris(hydroxymethyl)aminomethane (THAM), and the match with the use of nine organic solvents of methanol, dimethyl sulfoxide, ethanol, N,?N-dimethylformamide, acetonitrile, isopropyl alcohol, 1,4-dioxane, acetone, and tetrahydrofuran mainly in the presence of water in 20 mL scintillation vials. Racemic (R,S)-(±)-sodium ibuprofen dihydrate, a well-known ibuprofen salt and the newly discovered racemic (R,S)-(±)-THAM ibuprofen, appeared as white-squared powders with a molecular weight of 327.42 g/mol, a melting point of 160.17°C, and the apparent solubility product, K′_sp, of 6.0 × 10^?4 M² at 25°C were successfully synthesized by the initial salt screening methods. The new amine salt of ibuprofen was monoclinic and had a space group of P2₁/c and lattice parameters of a = 17.578(8)°, b = 10.428(4)°, c = 9.991(4) Å, α = 90.00°, β = 97.17(1)°, γ = 90.00°, and V = 1,817.05(244) ų. The aspect ratio of the amine salt crystals of ibuprofen of ≈ 1.0 implied that the crystals had a better flowability than the sodium salt counterparts. This amine salt of ibuprofen was more stable in moist or dried atmospheres and was more hydrophobic than the sodium salt of ibuprofen. Moreover, the slow dissolution of this amine salt of ibuprofen might have made it less bitter and more suitable as a sustained release drug than the sodium salt of ibuprofen. The future work is to search for the different polymorphs of this amine salt of ibuprofen and to extend the initial salt screening working logics to the formation of co-crystals.     

Synthesis and characterization of Bi2S3 nanorods by solvothermal method in polyol media

Bi₂S₃ nanorods were synthesized via a simple solvothermal process in polyol media through the reaction between Bi(NO₃)₃·5H₂O, urea and CS₂ at 150 °C for 15 h using diethylene glycol as solvent. The nanorods were characterized by XRD, TEM and SAED. The results showed that the products were well-crystallized orthorhombic phase with lattice parameters a = 11.15 Å, b = 11.3 Å and c = 3.984 Å, which are consistent with the value in standard JCPDS card No. 17-0320. DEG served as an excellent solvent and structure director. Besides, compared to water and EG as solvents, the DEG system can provide a mild and homogenous condition, which is favorable to anisotropic growth and increases the yield of high quality Bi₂S₃ nanorods. Based on the experimental results, the growth mechanism was discussed.     

Transformation of microporous titanium glycolate nanorods into mesoporous anatase titania nanorods by hot water treatment

High surface area titanium glycolate microporous multi-faceted nanorods were synthesized from the reaction of titanium alkoxides (Ti(OEt)₄, Ti(O ⁱ Pr)₄, or Ti(O ⁿ Bu)₄) with ethylene glycol, using a sol–gel reflux method. The specific surface area of the as-synthesized titanium glycolate nanorods obtained from Ti(OEt)₄ is ~480 m²/g. A hot water treatment at 90 °C for 1 h transformed the titanium glycolate microporous nanorods into mesoporous anatase TiO₂ nanorods. The shape of the nanorods was conserved after hot water treatment and the microporous to mesoporous transformation took place without significant change in the surface area (477 m²/g). Micro Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, solid state NMR, and nitrogen adsorption/desorption were used to characterize the samples. As a demonstration of potential applications, the thus formed mesoporous anatase TiO₂ nanorods were tested for their photocatalytic efficiency in the degradation of crystal violet, and a photodegradation mechanism is proposed.     

Synthesis and nonlinear optical properties of novel Y-type polyurethanes with high thermal stability of dipole alignment

2,3-Di-(2′-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and condensed with 2,4-toluenediisocyanate and 3,3′-dimethoxy-4,4′-biphenylenediisocyanate to yield novel Y-type polyurethanes 4–5 containing 2,3-dioxy benzylidenemalononitrile group as a nonlinear optical (NLO)-chromophore, which constituted parts of the polymer backbones. Polyurethanes 4–5 were soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed a thermal stability up to 270 °C in thermogravimetric analysis thermograms and the glass-transition temperatures (T _g) obtained from differential scanning calorimetry thermograms were around 116–135 °C. The second harmonic generation (SHG) coefficients (d ₃₃) of poled polymer films at 106.4 mm⁻¹ fundamental wavelength were around 9.07 × 10⁻¹⁹ C (2.72 × 10⁻⁹ esu). The dipole alignment exhibited high thermal stability up to 10 °C higher than T _g, and there was no SHG decay below 145 °C due to the partial main-chain character of the polymer structure, which was acceptable for nonlinear optical device applications.     

Experimental hydrothermal characteristics of minichannel heat sink using various types of hybrid nanofluids

The hydrothermal characteristics of minichannel heat sink are analyzed experimentally by using deionized (DI) water based different nanoparticles mixture dispersed hybrid nanofluids. Al₂O₃, MgO, SiC, AlN, MWCNT and Cu nanoparticles are considered for this study. Different nanoparticles combinations (oxide-oxide, oxide-carbide, oxide-nitride, oxide-carbon nanotube and oxide-metal) in 50/50 vol ratio with base fluid (DI water) have been taken as coolants for volume concentration of 0.01%. Effects of volume flow rate (0.1–0.5LPM), fluid inlet temperature (20–40 °C) and Reynolds number (50–500) are studied for heat flux of 50 W/cm². Convective heat transfer coefficient and pressure drop are increased by about 42.24% and 22% for Al₂O₃ + MWCNT hybrid nanofluid. The maximum reduction of 21.36% in thermal resistance is obtained for Al₂O₃ + MWCNT hybrid nanofluid in comparison to DI water. Heat transfer effectiveness and figure of merit are above one for all the hybrid nanofluids which conclude that hybrid nanofluid is better option for electronics cooling over DI water. Al₂O₃ + MWCNT hybrid nanofluid is better in terms of heat transfer effectiveness; whereas, Al₂O₃ + AlN hybrid nanofluid (oxide-nitrite mixture) has maximum heat transfer coefficient to pressure drop ratio and coefficient of performance.     

Density and Volume Fraction of Supercritical CO<Subscript>2</Subscript> in Pores of Native and Oxidized Aerogels

The density and volume fraction of an adsorbed phase of carbon dioxide (CO₂) in aerogels was investigated using a formalism based on independent measurements of neutron transmission and small-angle neutron scattering from fluid-saturated absorbers (Rother et al. J. Phys. Chem. C 111, 15736 (2007)). The range of excess fluid pressures (0 <  P <  8 MPa) and temperatures (T = 35°C and 80°C) corresponded to the supercritical regime above the critical temperature T _C = 31.1°C and critical density ρ _C = 0.468 g · cm⁻³ of the bulk fluid. The results demonstrate that a porous aerogel matrix works to create an adsorbed phase with liquid-like fluid densities reaching ~1.1 g · cm⁻³ and ~0.8 g · cm⁻³ at T = 35°C and 80°C, respectively. Thus, despite the fact that the density and volume fraction of the adsorbed fluid both decrease with temperature, the dense adsorbed phase is still present in the aerogel at temperatures far exceeding the T _C. Heat treatment (“oxidation”) of the aerogel at 500°C for 2 h, which removes a significant fraction of the alkyl groups from the aerogel surface, has little effect on the adsorption properties. The observed reduction of the density and volume fraction of the adsorbed CO₂ with temperature and its minor dependence on the surface modification are consistent with predictions of the pore-filling model.     

Synthesis of Zn/Co/Fe-layered double hydroxide nanowires with controllable morphology in a water-in-oil microemulsion

The Zn/Co/Fe-layered double hydroxide nanowires were synthesized via a reverse microemulsion method by using cetyltrimethyl ammonium bromide (CTAB) /n-hexane/n-hexanol/water as Soft-Template. ZnSO₄, CoSO₄, Fe₂(SO₄)₃ and urea were used as raw materials. The influence of reaction temperature, time, urea concentration and Cn (molar ratio of cetyltrimethyl ammonium bromide to water) on the structure and morphology of Zn/Co/Fe-layered double hydroxides was investigated. The samples were characterized using Transmission Electron Microscopy (TEM), Inductively Coupled Plasma (ICP), X-ray Diffraction (XRD) and Infrared Absorption Spectrum (IR). The results indicate that higher temperature is beneficial to the formation of layered double hydroxides, but particles apart from nanowires could be produced if temperature is up to 120 °C. By varying the temperature, reaction time, urea concentration and Cn, we got the optimum conditions of synthesizing uniform Zn/Co/Fe-layered double hydroxide nanowires: 100 °C, more than 12 h, Cn: 30–33, urea concentration: 0.3 M.     

Crystallization behavior of PVDF/PMMA blends prepared by in situ polymerization from DMF and ethanol

The crystallization behavior of poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blends was investigated at different PMMA content and from two solvents N,N-dimethylformamide (DMF) and ethanol. The PVDF/PMMA blends were obtained by in situ polymerization of methyl methacrylate (MMA) in the solution of PVDF in DMF. The crystalline phases of PVDF were dependent on crystalline solvents and independent on PMMA content. For the in situ PVDF/PMMA blends, β phase of PVDF was predominant when they were crystallized from their good solvent DMF, while PVDF exhibited well-defined α and β phases from non-solvent ethanol. However, the relative fraction of β phase of PVDF in blends crystallized from ethanol varied with PMMA content. The crystallization morphology was related to crystallization solvent and PMMA content. The in situ blends crystallized from DMF and ethanol presented spherulites morphology and numerous minute particle structures, respectively. The addition of PMMA could reduce the spherulite size of PVDF. Thermal properties of in situ blends were also dominated by crystallization solvent and PMMA content. For the blends crystallized from DMF, their peak melting temperatures and lamellar thickness calculated by WAXD showed a first increasing and then decreasing tendency. At the same PMMA content, the blends crystallized from ethanol had a higher degree of crystallinity (X _c) of PVDF compared with those from DMF. In addition, the X _c calculated by DSC increased noticeably at PMMA content of 1.0 wt% and afterward it decreased with PMMA content, regardless of the kind of crystallization solvent. Besides, the hydrophilicity of the PVDF/PMMA blends was improved with PMMA content based on contact angle measurements.     

Facile tailoring of titanate nanostructures at low alkaline concentration by a solvothermal route

Nanostructured titanates with different morphologies such as nanoflakes, nanotubes, and nanofibers have been selectively synthesized by a simple solvothermal treatment of commercial anatase TiO₂ using the mixed water–ethanol cosolvent at low alkaline concentration. The effects of solvothermal temperature, volume ratio of H₂O to C₂H₅OH, amount of NaOH and solvents on the formation of titanate nanostructures have been systematically studied through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). At low concentration of NaOH solution (the actual concentration of OH⁻ in the solution is only 0.58 M), different titanate nanostructures are achieved by simply changing the volume ratio of H₂O to C₂H₅OH at 180 °C and titanate nanotubes can be synthesized between 100 and 180 °C. A probable formation mechanism is proposed based on XRD, SEM and TEM analysis. The influence of cosolvent on the transformation from anatase TiO₂ to titanate is also investigated.     

The impact of K+ content on the structural transformations and morphological changes during the thermal treatment of α-MnO2 nanorods

The effect of heat treatment on the structure and morphology of α-MnO₂ nanorods with different potassium contents was investigated. These nanorods, prepared by ion exchange, were thermally treated at 500, 800, 1000 and 1100 °C, and characterized with X-ray diffraction and electron microscopy. The structure and morphology of the starting sample remained preserved up to 500 °C. The first structural and morphological changes were observed when α-MnO₂ nanorods with different potassium contents were heated at 800 °C. The sample with the highest potassium content decomposed only partially to α-Mn₂O₃, while the decomposition of the α-MnO₂ to α-Mn₂O₃ was complete in the sample with the lowest potassium content. Morphologically, both samples were composed of nanorods and grains. When the temperature was increased to 1000 and 1100 °C, both the structure and morphology changed: the α-MnO₂ nanorods completely decomposed to Mn₃O₄ grains. The acidic media in which the ion exchange took place shortened the α-MnO₂ nanorods.     

Synthesis of <Emphasis Type="Italic">γ</Emphasis>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanowires through a boehmite precursor route

Crystalline γ-Al₂O₃ nanowires with diameter, 20–40 nm, length above 600 nm and aspect ratio above 30 have been successfully synthesized by thermal decomposition of boehmite (γ-AlOOH) precursors obtained via hydrothermal route by using AlCl₃, NaOH and NH₃ as starting materials. Thermogravimetric analysis (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED) and high resolution transmission electron microscope (HRTEM) were used to characterize the features of the as-made γ-Al₂O₃ nanowires and their γ-AlOOH precursors. The pH value of the solution and the mixed precipitant play important roles in the formation of γ-AlOOH nanowires. After calcination at 500°C for 2 h, the orthorhombic γ-AlOOH transforms to cubic γ-Al₂O₃ and retains nanowire morphology.     

Effect of drawing on the dielectric properties and polarization of pressed solution cast β-PVDF films

Poly(vinylidene fluoride), PVDF, samples containing exclusively the polar β phase were obtained by crystallization from N,N-dimethylformamide (DMF) solution at 60 °C and subsequent pressing. Some of these samples were uniaxially drawn at 120 °C at draw ratio of 4, resulting in oriented films. Oriented and unoriented samples were characterized as to relative fraction of β phase, degree of crystallinity and orientation by infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD). The dependence on frequency of the real ( e_\textr^￠ \varepsilon_{\text{r}}^{\prime} ) and imaginary ( e_\textr^￠￠ \varepsilon_{\text{r}}^{\prime\prime} ) components of the relative permittivity of the samples was determined between 10⁴ and 1.7 × 10⁷ Hz. The coercive field and stable and metastable remanent ferroelectric polarization were determined from the hysteresis loop obtained by the ramp voltage technique, described in detail in this work. The results allowed verification of the effect of drawing on structure and of the resulting structure on the dielectric properties, remanent polarization, and coercive field of β-PVDF. A possible effect of the crystal–amorphous interphase region on the metastable remanent polarization is suggested. The results obtained with the oriented and unoriented samples were compared with those obtained for films commercialized by Piezotech S.A.     

1D sub 10 nm nanofabrication of ultrahydrophobic Ag@TiO2 nanowires and their photocatalytic,UV shielding and antibacterial properties

Here we report the synthesis of 1D TiO₂ sub 10 nm nanowires through one pot hydrothermal method in an alkaline NaOH medium at 95 °C for 36 h. Further, these TiO₂ nanowires were embellished with silver (Ag) using polyvinylpyrrolidone (PVP) and ethylene glycol (EG) based solvothermal route at 160 °C for 4 h. With Ag decoration the photocatalytic activity was enhanced and the complete photooxidation of Methylene Blue (MB) was achieved in 35 min under optimized conditions. Super- and ultra-hydrophobic coating on cotton fabric exhibited a consistent antibacterial activity with enhanced UV-blocking property. Enhanced multifunctional properties observed were primarily attributed to the formation of Ag decorated 1D sub 10 nm TiO₂ nanowires heterojunctions achieved using facile chemical route. Hence, such multiple functionalities make the 1D sub 10 nm TiO₂ nanowires good candidate for industrial and domestic wastewater treatment.     

The effect of seed layer thickness on alignment and morphology of ZnO nanorods

Thin films of ZnO of 20, 40,160 and 320 nm thickness were deposited on Si (100) substrates by rf-magnetron sputtering and then nanorods were grown on the seed layer at 95 °C for 2 h. The ZnO nanorods were synthesized in C₆H₁₂N₄ and Zn (NO₃)₂·6H₂O solution by a hydrothermal method and the effect of seed layer thickness on the alignment, diameter, density and growth rate of nanorods was studied.The results revealed that the alignment of nanorods depended on crystallinity, grain size and roughness frequency of the sputtered seed layer, so that, with increase of seed layer thickness, crystallinity improved. In addition the grain size increased and the roughness frequency decreased and hence alignment and diameter of nanorods increased.Finally, we present a model for the effect of seed layer thickness on the alignment and diameter of the nanorods.     

Preparation,Physical Properties,and Stability of Gambogic Acid-Loaded Micelles Based on Chitosan Derivatives

The objective of this study is to find out an optimized formulation of water insoluble anticancer drug gambogic acid (GA)-loaded chitosan derivatives micelles. After preliminary test, four factors (the amount of N-octyl-O-sulfate chitosan (AOSC), the amount of GA, volume of ethanol, and dialysis temperature) and three levels for each factor that might affect the formation of micelles were selected and arranged in L₉ (3⁴) orthogonal experimental design to optimize the formulation of GA-loaded micelles. To compare each of the micellar formulations quantitatively, an overall desirability function was defined and calculated based on three assessment indices (drug content, loading efficiency, and entrapping efficiency of micelles). The optimized formulation was 8 mg of GA dissolved in 0.3 mL of ethanol, 12 mg of AOSC dissolved in 2 mL of H₂O, respectively. The drug solution and blank micellar solution were mixed, followed by dialysis against water at 25°C. The mean size of micelle was 100 nm approximately. Lyophilized samples could keep stable for at least 2 months when it was stored at 4°C. These data suggest that the amphiphilic chitosan derivative may improve the water solubility of GA and thus be used as its nano-carrier.