Synthesis of Aligned ZnO Nanorod Array on Silicon and Sapphire Substrates by Thermal Evaporation Technique

High density ZnO nanorods were grown by thermal evaporation of Zn powder at 700℃ on Si （100） and sapphire （0001） substrates at atmospheric pressure without adding any catalyst. The nanorods were characterizated in terms of their structural and optical properties. The nanorods grown on Si have a diameter of 350-400 nm and a length of 1.2 μm while those on sapphire have a diameter of 600-800 nm and a length of 2.5 μm. During the structural characterization, it is noticed that the rods grow along the （0002） plane with perfect hexagonal facet. The room temperature photoluminescence spectrum showed a strong UV emission peak at 385 nm with a weak green band emission, which confirms that nanorods have good optical properties. It is observed that the oxygen partial pressure plays an important role to control the shape and size of the nanorods in thermal evaporation growth technique.

A novel approach to fabricate Zn coating on Mg foam through a modified thermal evaporation technique

Zn enriched coatings with distinct microstructures and properties were fabricated on Mg foams by a modified thermal evaporation technique using a tubular resistance furnace. As the temperature and kinetic energy of Zn vapor varied along the tubular system, a spatial variation of preparation conditions was created and the obtained coatings were found to follow two growth mechanisms： a thermal diffusion pattern in high-temperature zone and the a relatively low-temperature deposition model. AZn-based deposition coating with dense texture and nearly uniform structure was acquired while Mg foam was placed 20 cm far from the evaporation source, where the Zn vapor deposition model dominated the coating growth.Mechanical properties and bio-corrosion behaviors of the samples were investigated. Results showed that the Zn coatings brought dramatic improvements in compression strength, but exhibited differently in biodegradation performance. It was confirmed that the diffusion layer accelerated corrosion of Mg foam due to the galvanic effect, while the Zn-based deposition coating displayed excellent anti-corrosion performance, showing great potential as bone implant materials. This technique provides a novel and convenient approach to tailor the biodegradability of Mg foams for biomedical applications.

Application of solvent evaporation technique for pure drug crystal spheres preparation

An innovative application ofthe solventevaporation technique was suggested.Solventevaporation tech nique is a technique for drug encapsulation and nanosphere preparation.The widely used technique is also facing the problem of low actual drug entrapment percent,which is not economic from the industrial view.The goal of this work is trying to use the advantage of this technique concerning the product sphericity and the ability to control particle size,to prepare a drug as pure crystals spheres.Ibuprofen is selected as a model drug.The spheres are formed by using Polyvinyl pyrrolidone(PVP)or Polyethylene glycol(PEG)as an anti-aggregating agent but not formed on using tween or span.Particle size and actual drug content depend on the concentrations the anti-aggregating agent used.Surfaces of the drug crystal spheres are porous with empty sphere internal structure on using PvP but spongy and rough on using PEG.The drug has its identity chemical form in the drug crystal spheres.IR scan of spheres prepared on using PEG showed a characteristic ether peak.DSC showed melting endothermic peak of PEG,but X-ray showed minor change in the drug crystal patterns.Drug release profiles from crystal spheres prepared with the same anti-aggregating agent are close to each other.The drug release profiles from drug crystal spheres prepared by using PEG are more controlled than that prepared by using PVP.The drug release mechanism is diffusion.It was concluded that,the same technique could be suggested for preparation ofother biomedical material in pure crystals spheres with controlled particle size.These properties may encourage to prepare very small particles with spherical shape for inhalation or injection as an innovative particle technology application for the widely used technique.

Synthesis, Growth and Characterization of Nonlinear Optical Single Crystal of Serine Succinate

Nonlinear optical single crystal of Serine Succinate (SSA) was grown from a mixed solvent of water, ethanol and methanol. Since amino acid exhibits nonlinear optical property, it is of interest to dope them in serine. The overwhelming success of molecular engineering in controlling nonlinear optical properties in last decade has prompted better initiative in crystal engineering. In the present study single crystals of serine doped with succinic acid in different ratios have been grown by slow evaporation solution growth method. Grown serine succinate crystals were subjected to various characterization techniques. The cell parameters of the grown crystals were characterized by X-ray diffraction analysis. FT-Raman spectral studies were carried out on the SAA grown material to confirm the synthesized compound and the functional groups of serine succinate single crystal were identified from FTIR analysis. The optical transparency and upper cut off value of UV transmission spectrum of SSA crystal were recorded. Fluorescence study was also carried out for the grown materials. The mechanical hardness was estimated by Vickers’s micro hardness tester. The second harmonic generation (SHG) of the grown crystal was confirmed by Kurtz powder technique. Thermal properties of serine succinate crystal were evaluated with thermogravimetric, differential thermal and differential scanning calorimetric analyses. The SEM studies were also reported.

Structural Morphological and Optical Properties of SnSb_2S_4 Thin Films Grown by Vacuum Evaporation Method

SnSb2S4 thin films were prepared from powder by thermal evaporation under vacuum of 1.33 × 10^-4 Pa （ 10^-6 Torr） on unheated glass substrates. The effect of thickness on the structural, morphological and optical properties of SnSb2S4 thin films was investigated. Films thickness measured by interference fringes method varied from 50 to 700 nm. X-ray diffraction analysis revealed that all the SnSb2S4 films were polycrystalline in spite without heating the substrates and the crystallinity was improved with increasing film thickness. The microstructure parameters： crystallite size, strain and dislocation density were calculated. It was observed that the crystallite size increased and the crystal defects decreased with increasing film thickness. In addition, by increasing the film thickness, an enhancement in the surface roughness root-mean-square （RMS） increased from 2.0 to 6.6 nm. The fundamental optical parameters like band gap, absorption and extinction coefficient were calculated in the strong absorption region of transmittance and reflectance spectrum. The optical absorption measurements indicated that the band （Eg） gap of the thin films decreased from 2.10 to 1.65 eV with increasing film thickness. The refractive indexes were evaluated in transparent region in terms of envelope method, which was suggested by Swanepoul. It was observed that the refractive index increased with increasing film thickness.

P3HT STRIPE STRUCTURE WITH ORIENTED NANOFIBRILS ENABLED BY CONTROLLED INCLINING EVAPORATION

The preparation of the poly（3-hexylthiophene） （P3HT） stripe structure with oriented nanofibrils prepared by controlled inclining evaporative technique is reported. The distance of the adjacent stripes could be controlled from 40 μm to 100 μm by decreasing the inclining angle. The oriented nanofibrils in the stripes can be obtained because the P3HT lamellae diffuse directionally and form 1D crystals at the three-phase contact line of the drop. In order to get the oriented P3HT stripes, the proper solvent evaporation rate which is controlled by the inclining angle and the wettability of the substrate must be carefully chosen to match the P3HT 1D crystallization rate. It is found that large inclining angle and the hydrophilic substrate （for example： glass and PEDOT） are beneficial to get P3HT stripe structure with oriented nanofibrils.

Preparation and characterization of biomimetic adsorbent from poly-3-hydroxybutyrate

Biomimetic adsorbent named as PHBBMA was prepared from lipophilic poly-3-hydroxybutyrate （PHB） by a modified double emulsion solvent evaporation method. PHBBMA, characterized by using scanning electron microscope and nitrogen adsorption/desorption measurements, is porous spherical particles. The characterization with the thermal gravimetric analysis and differential scanning calorimetry, 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that PHBBMA preparation was a physical process without chemical reaction. The adsorption of PHBBMA for o-nitrochlorobenzene （o-NCB） was fitted better by Langmuir model than by Freundlich model, while the pseudo second-order model fitting was better than the pseudo first-order model fitting. The maximal adsorption capacity of PHBBMA for o-NCB was 57.83 mg/g at 30°C, although its specific surface area （S BET ） was only 8.45 m 2 /g. PHBBMA is a safe and environmental friendly adsorbent with high adsorption capacity because its component is innocuous and biodegradable PHB produced reusing wastes and contaminants, no byproduct can produced, and its ester and hydrocarbyl groups have strong affinity with organochlorine compounds. The further work will focus on the modification and improvement of PHBBMA in order to increase its S BET and adsorption capacity.

Optimization of Jiawei Qing'e Oral Fast Disintegrating Tablets Based on Response Surface-Central Composite Design

Abstract: Objective To apply the response surface-central composite design to developing and optimizing the oral fastdisintegrating tablets (ODT) formulation for Jiawei Qing’e, a kind of prescription of Chinese herbal medicine.Methods The bitterness of Jiawei Qing’e was masked using Eudragit E-100 by solvent evaporation technique.Response surface approach was applied to investigating the interaction of formulation parameters in optimizing theformulation. The independent variables were Eudragit E-100/drug ratio (X1), amount of disintegrants (X2), and theamount of diluents (X3). The disintegration time (Y1), hardness (Y2), and weight variations of the tablets werecharacterized. Results The models predicted levels of X1= 4.63%, X2= 5.25%, and X3= 34.33%, for the optimalformulation having a hardness of 3.0 kg with the disintegration time of 30 s within experimental region. The observedresponse of Y1= 26.5 s and Y2= 3.14 kg reasonably agreed with the predicted response. Conclusion Responsesurface methodology shows the good predictability and reliability in optimizing the formulation. The optimized ODTof Jiawei Qing’e has acceptable taste, rapid disintegrating ability, and good mechanical strength.

Substrate Temperature-Dependent Physical Properties of Thermally Evaporated Sn4Sb6S13 Thin Films

In this work, the homogenous thin films of sulfosalt Sn4Sb6S13 were successfully synthesized by the thermal evaporation technique onto coming 7059 glass substrates heated at various temperatures in the range of 30--200 ℃. The surface morphology and structural characteristics of Sn4Sb6S13 films were analyzed by atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray, respectively. The X-ray diffraction analysis revealed that Sn4Sb6S13 thin films crystallized in monoclinic structure according to a preferential direction （6 11）. An improvement in the structural properties by increasing the substrate temperature was observed. The values of some important parameters such as absorption coefficient （x）, band gap （Eg）, refractive index （n）, extinction coefficient （k）, and dielectric constant （Eg） of thin film were determined. The absorption coefficient was larger than 105 cm-l in the visible range. The electron transition of Sn4Sb6S13 films was direct allowed with the values that decreased （2-1.69 eV） by increasing substrate temperature from 30 to 200 ℃,The dispersion data obeyed the single oscillator relation of the Wemple-DiDomenico model and Cauchy model. The electrical free carrier susceptibility and the carrier concentration of the effective mass ratio were estimated according to the model of Spitzer and Fan.