Characterization of epitaxial GaAs MOS capacitors using atomic layer-deposited TiO2/Al2O3 gate stack: study of Ge auto-doping and p-type Zn doping

Few-wall carbon nanotubes were synthesized by methane/acetylene decomposition over bimetallic Fe-Mo catalyst with MgO (1:8:40) support at the temperature of 900°C. No calcinations and reduction pretreatments were applied to the catalytic powder. The transmission electron microscopy investigation showed that the synthesized carbon nanotubes [CNTs] have high purity and narrow diameter distribution. Raman spectrum showed that the ratio of G to D band line intensities of I _G/I _D is approximately 10, and the peaks in the low frequency range were attributed to the radial breathing mode corresponding to the nanotubes of small diameters. Thermogravimetric analysis data indicated no amorphous carbon phases. Experiments conducted at higher gas pressures showed the increase of CNT yield up to 83%. M?ssbauer spectroscopy, magnetization measurements, X-ray diffraction, high-resolution transmission electron microscopy, and electron diffraction were employed to evaluate the nature of catalyst particles.     

Peptide Paratope Mimics of the Broadly Neutralizing HIV‐1 Antibody b12

The broadly neutralizing HIV‐1 antibody b12 recognizes the CD4 binding site of the HIV‐1 envelope glycoprotein gp120 and efficiently neutralizes HIV‐1 infections in vitro and in vivo. Based on the 3D structure of a b12 ? gp120 complex, we have designed an assembled peptide (b12‐M) that presents the parts of the three heavy‐chain complementarity‐determining regions (CDRs) of b12, which contain the contact sites of the antibody for gp120. This b12‐mimetic peptide, as well as a truncated peptide presenting only two of the three heavy‐chain CDRs of b12, were shown to recognize gp120 in a similar manner to b12, as well as to inhibit HIV‐1 infection, demonstrating functional mimicry of b12 by the paratope mimetic peptides.     

Physicochemical stability of calcium alginate beads immobilizing TiO2 nanoparticles for removal of cationic dye under UV irradiation

Recently, there have been considerable interests to immobilize photocatalyst in alginate beads for removing pollutants from water sources. However, the feasibility of using alginate beads in industry largely depends on its long‐term stability during operation. This study investigated the physicochemical stability of alginate/titanium dioxide beads (Alg/TiO₂) when exposed to UV irradiation in aqueous environment. The degradation of Alg/TiO₂ beads was evident because the diameter and mass of the beads was reduced by 12% and 40%, respectively, after 120 h of irradiation. A substantial amount of TiO₂ was leached into the external medium. Consequently, the removal efficiency of model cationic dye was found to reduce after every process cycle. Morphological analysis showed the formation of cavities on the surface of the Alg/TiO₂ beads. Interestingly, the blank alginate beads degraded more rapidly than the Alg/TiO₂ beads, confirming the UV‐shielding effect of TiO₂. Nevertheless, this study reveals the need to improve the UV stability of alginate‐based beads before they can be considered for practical application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45002.     

Production of Furfural from Lignocellulosic Biomass Using Beta Zeolite and Biomass-Derived Solvent

The production of furfural from the C₅ monosaccharides xylose, arabinose and ribose, as well as from real biomass (corn fiber), was studied using H-Beta zeolite as catalyst in a monophasic system with the biomass-derived solvent, gamma-valerolactone. Due to the combination of Brønsted and Lewis acid sites on this catalyst (Brønsted:Lewis ratio = 1.66), H-Beta acts as a bifunctional catalyst, being able to isomerize (Lewis acid) and dehydrate (Brønsted acid) monosaccharides. The combination of Lewis and Brønsted acid functionality of H-Beta was shown to be effective for the isomerization of xylose and arabinose, followed by dehydration. While no advantages were found in the conversion of xylose, higher furfural yields were achieved from arabinose, using H-Beta, 73 %, compared to sulfuric acid (44 %) and Mordenite (49 %). The furfural yields from corn fiber for H-Beta, H-Mordenite and sulfuric acid were 62, 44, and 55 %, respectively, showing that H-Beta is particularly effective for conversion of this biomass feedstock composed of 45 wt% hemicellulose, of which 66 % is xylose and 33 % arabinose.     

Urethane‐forming reaction kinetics and catalysis of model palm olein polyols: Quantified impact of primary and secondary hydroxyls

Model palm olein natural oil polyols (NOPs) with varying ratios of primary to secondary hydroxyls were synthesized, characterized, and evaluated in reaction kinetics study with isocyanate in formation of polyurethanes. Reaction rate constants and activation energies associated with primary and secondary hydroxyls of NOPs were quantified. The kinetic study in toluene shows that the NOP containing primary hydroxyls have three times higher reaction rate constants in noncatalyzed reaction with 4,4′‐diphenylmethane diisocyanate (4,4′‐MDI) compared to the model NOP containing only secondary hydroxyls, which is associated with higher activation energy of secondary hydroxyls. However, the difference in reaction rate constants of primary and secondary hydroxyls in NOPs diminished in the reactions catalyzed with dibutyltin dilaurate. Bulk polymerization reaction confirms the kinetics results in toluene, showing that the model NOP containing primary hydroxyls reached gel time at a faster rate. Evaluation of elastomers from bulk polymerization shows low degree of phase separation of hard and soft segments for elastomers based on the model NOPs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42955.     

4‐Biphenylalanine‐ and 3‐Phenyltyrosine‐Derived Hydroxamic Acids as Inhibitors of the JumonjiC‐Domain‐Containing Histone Demethylase KDM4A

Overexpression of the histone lysine demethylase KDM4A, which regulates H3K9 and H3K36 methylation states, has been related to the pathology of several human cancers. We found that a previously reported hydroxamate‐based histone deacetylase (HDAC) inhibitor (SW55) was also able to weakly inhibit this demethylase with an IC₅₀ value of 25.4 μm . Herein we report the synthesis and biochemical evaluations, with two orthogonal in vitro assays, of a series of derivatives of this lead structure. With extensive chemical modifications on the lead structure, also by exploiting the versatility of the radical arylation with aryldiazonium salts, we were able to increase the potency of the derivatives against KDM4A to the low‐micromolar range and, more importantly, to obtain demethylase selectivity with respect to HDACs. Cell‐permeable derivatives clearly showed a demethylase‐inhibition‐dependent antiproliferative effect against HL‐60 human promyelocytic leukemia cells.     

Comparison of Isolated Indentation and Grid Indentation Methods for HVOF Sprayed Cermets

This paper compares the results of two approaches of instrumented indentation for characterization of mechanical properties of HVOF coatings. Three types of HVOF sprayed coatings (Cr₃C₂-NiCr, WC-Co, (Ti, Mo)(C,N)-NiCo) were investigated by the means of isolated nanoindentation and grid indentation methods. The results of the isolated indentation revealed hardness and elastic modulus of the individual phases in very good agreement with the corresponding bulk material. The grid indentation method, based on statistical evaluation of a large number of indentations, was influenced by the carbide-matrix interface, which gave rise to a third peak apart from the two peaks corresponding to the carbides and metallic matrix. As a consequence, the bimodal Gaussian fit was insufficient and a trimodal fit had to be used. The results extracted from low load grid nanoindentations were quite close to the results of isolated indentations whereas higher load grid nanoindentation revealed overall properties of the coating.     

Dry Fractionation Approach in Concentrating Tocopherols and Tocotrienols from Palm Fatty Acid Distillate: A Green Pretreatment Process for Vitamin E Extraction

Palm fatty acid distillate (PFAD) is a rich source of vitamin E. As compared to other vegetable oil, PFAD has higher tocotrienol (70–80%) over tocopherol content, which makes it a valuable source for vitamin E extraction. Current vitamin E extraction methods are not sustainable due to the intensive usage of chemical and high operational cost. Hence, the present study investigated for the first time using dry fractionation process as a green and economical pretreatment method for separating solid fraction (stearin) and liquid fraction (olein) in order to concentrate vitamin E from PFAD in olein fraction. We examined the dry fractionation conditions: crystallization ending temperature (36–44 °C), cooling rate (0.3 and 1.5°C min⁻¹), stirring speed (20–125 rpm), and holding time (0–60 min) on the composition of unsaturated and saturated fatty acids as well as vitamin E content in liquid fraction (olein) and solid fraction (stearin) using gas chromatography and high performance liquid chromatography, respectively. In most of these conditions, vitamin E was ultimately higher in olein fraction as compared to stearin fraction, which is correlated with the high degree of unsaturation. Under a cooling rate of 0.3°C min⁻¹, 90 rpm stirring speed, and ending crystallization of 38 °C, the highest vitamin E rich olein fraction was attained with 1479 ± 10.51 ppm in 50 g olein fraction as compared to 1366 ± 7.94 ppm in 500 g of unfractionated PFAD.