Measurement of specific surface free energy of ruby and quartz single crystals using contact angle of liquids

The specific surface free energy of ruby and quartz single crystal was experimentally obtained using contact angle of water and formamide droplets on the crystal surfaces, and compared with the morphology of each crystal. The ruby crystals satisfied Wulff's relationship even though their shape were not equilibrium form. The specific surface free energies of the growing faces of synthetic quartz crystal, ‐X, +X, Z, and S faces were obtained as 51.9, 55.6, 57.4, and 58.9 mN/m, respectively. The growth rates of these faces were 0.09, 0.23, 0.28, and 0.33 mm/day, respectively. The growth rate of each face of the quartz crystal can be regarded as a function of the experimentally obtained specific surface free energy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Relation between electrophoretic behavior and molecular shapes of aromatic anions.

The capillary electrophoretic behavior of 44 aromatic organic ions was investigated. The observed ionic radii (r(obs0)) for the aromatic organic ions were obtained from the electrophoretic mobilities of sodium tetraborate (pH 9.2), potassium tetraborate (pH 9.2), ammonium borate (pH 9.2), and trisodium phosphate (pH 11.7) buffers with zero ionic strength. The linear relationships between the r(obs0)) values and the ionic radii (r(calc)), calculated by either the AM1 or PM3 method, were determined for benzyltrialkylammonium and aromatic sulfonate ions. However, the r(obs0)) values were constant for the aromatic carboxylate ions in buffers, in spite of the different r(calc) values. This indicates that aromatic carboxylate ions, such as benzenecarboxylate, pyridinecarboxylate, naphthalenecarboxylate, and anthracenecarboxylate ions, migrate as planar ions in buffers, whereas aromatic sulfonate ions could migrate as approximately spherical ions.     

Specific surface free energy and morphology of chlorapatite crystals studied by modified Wilhelmy method

Barium chlorapatite [Ba₅Cl(PO₄)₃] and strontium chlorapatite [Sr₅Cl(PO₄)₃] crystals were grown from a sodium chloride flux. The aspect ratios for these crystals were distributed in the range 1–9, and maximum number of crystals was observed in the range 3–4 for both chlorapatite crystals. The contact angle of water on (1 0 1? 0) face of each chlorapatite crystal was observed using a modified Wilhelmy method, where the change of liquid weight was measured instead of the crystal weight. The contact angle depends on the aspect ratio of the crystal. Both the advancing and the receding contact angles showed maximum value when the aspect ratios of the crystals were approximately 4 for both Ba₅Cl(PO₄)₃ and Sr₅Cl(PO₄)₃ crystals. The specific surface free energy of (1 0 1? 0) face was calculated using Neumann’s equation. The (1 0 1? 0) face of the crystals of the aspect ratio 4 has a minimum specific surface free energy, indicating that they have the most stable (1 0 1? 0) face when the aspect ratio is 4.     

Brillouin scattering study on the wave properties in thin SiC films

The modified Rayleigh wave velocities on the SiC hetero-epitaxial films have been investigated using a Brillouin scattering technique. The SiC nanoscopic films were formed on clean surface of Si substrates by the molecular ion beam technique or Ion beam induced chemical vapor deposition. Back scattering geometry was used to obtain the ripple Brillouin scattering from the film surface. Owing to the high stability of the measurement system, the precise velocity measurement was performed. As a result, Rayleigh wave velocity showed a clear dependence on the crystalline structure of SiC film, indicating that the shear moduli of very thin epitaxial films shows similar tendency with those of SiC bulk sample.     

Surface-modified carbon black for As(V) removal

This paper reports the results of the adsorption performance of As(V) removal by a commercial carbon black and its H2SO4-modified form in a single-ion situation. The influence of different process parameters and the physicochemical principles involved were studied in detail. Acid modification caused morphological changes in the virgin carbon black as evidenced by BET surface area measurements and SEM study. FTIR spectra showed the introduction of sulfonic acid group in the parent carbon due to H2SO4 treatment. TGA analysis revealed higher weight loss characteristics of the modified carbon, demonstrating the creation of functional groups. The point of zero charge (pH pzc) of the modified carbon black is highly acidic (3.5) compared to commercial carbon black (6.4). It directly infers the generation of acidic functional moieties in the carbon black. The adsorption experiments were carried out following batch equilibrium techniques. The kinetics and thermodynamics of adsorption were investigated to unveil the mechanism and nature of the adsorption process, respectively. The kinetic parameters of different models were calculated and discussed. The kinetics of adsorption can be expressed by a pseudo-second-order model and intraparticle diffusion was not the rate-determining step. Dependence of pH on adsorption showed maximum metal uptake in the range of 4-5 and inferred surface complexion as the principal mechanism of adsorption. The equilibrium adsorption data were modeled using Freundlich, Langmuir, and Dubinin-Kaganer-Radushkevich (DKR) isotherm equations and the corresponding isotherm parameters were calculated and discussed in detail.     

Sono-respond on thermosensitive polymer microgels based on cross-linked poly(N-isopropylacrylamide-co-acrylic acid)

Ultrasound (US) exposure strongly influenced thermosensitivity of microgels attracted with both N-isopropylacrylamide (NIPAM) and acrylic acid (AA) segments, due to that hydrogen bonds of carboxylic acid segments in microgels were broken by US and then the hydration with water occurred. US induced critical effects on the volume phase transition temperature of the swelled NIPAM gel (PNAM). It was observed after the US exposure that the particle size was increased and the phase transition of the microgels shifted toward larger temperature regions of the hydrodynamic diameter. FT-IR spectroscopic data of the swelled microgel showed that the free OH stretching band intensity of the COOH segments was enhanced by the exposure, but the band intensity returned to its original level without the US exposure. This meant that the US stimulus broke hydrogen bonding of the microgel and induced hydration of water in the hydrogel environment. Finally, regeneration of the hydrogen bonds in the microgel was occurred after the US exposure.     

High performance of thin nano-crystalline ZrN diffusion barriers in Cu/Si contact systems

A thermally stable thin diffusion barrier in Cu/Si contacts was developed using a thin nano-crystalline ZrN film. The Cu/ZrN/Si contact system using a reactively sputtered ZrN barrier with 20 nm in thickness consisting of several to 10 nm grains tolerated annealing at 600 °C for 1 h without any Cu penetration through the barrier. This was interpreted that the scarce structural change in the prepared nano-crystalline ZrN film due to annealing was favorite for the thermal stability of thin barrier application.     

Simultaneous analysis of highly polar pharmaceutical adulterants in slimming products by hydrophilic interaction liquid chromatography

A chromatographic method utilizing hydrophilic interaction liquid chromatography was developed for the estimation of highly polar pharmaceutical adulterants in commercial slimming products. Five adulterants, phenylpropanolamine, salbutamol, phenformin, buformin, and metformin, were successfully separated on an XBridge^? amide column (3.5 µm, 4.6?×?250 mm) using a mobile phase composed of acetonitrile/26.5 mM ammonium formate containing 0.1% formic acid (85:15) flowing at the rate of 0.8?mL/min. Wavelengths for monitoring the elution of these compounds were determined based on the wavelength of their absorption maxima (λ_max?=?208, 226, and 236 nm). The developed method was validated for specificity, linearity, accuracy, precision, and robustness. Interassay comparison showed that the performance of the hydrophilic interaction liquid chromatography-based method was superior to that of the traditional reversed-phase liquid chromatography-based method. Therefore, the proposed method is useful to analyze highly polar pharmaceutical adulterants in slimming products.