Remarkable bismuth-gold alloy decorated on MWCNT for glucose electrooxidation: the effect of bismuth promotion and optimization via response surface methodology

In this study, the carbon nanotube supported gold, bismuth, and gold-bismuth(Au/MWCNT, Bi/MWCNT, and Au-Bi/MWCNT) nanocatalysts were prepared with NaBH₄ reduction method at varying molar atomic ratio for glucose electrooxidation (GAEO). The synthesized nanocatalysts at different Au: Bi atomic ratios are characterized via x - ray diffraction (XRD), transmission electron microscopy (TEM), and N₂ adsorption-desorption. For the performance of AuBi/MWCNT for GAEO, electrochemical measurements are performed by using different electrochemical techniques namely cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Monometallic Au/MWCNT exhibits higher activity than Bi/MWCNT with 256.57 mA/mg (0.936 mA/cm²) current density. According to CV results, Au₈₀Bi₂₀/MWCNT nanocatalyst has the highest GAEO activity with the mass activity of 320.15 mA/mg (1.133 mA/cm²). For Au₈₀Bi₂₀/MWCNT, central composite design (CCD) is utilized for optimum conditions of the electrode preparation. Au₈₀Bi₂₀/MWCNT nanocatalysts are promising anode nanocatalysts for direct glucose fuel cells (DGFCs).     

Synthesis of nonperipherally tetra-[5-(diethylamino)-2-formylphenoxy] substituted metallophthalocyanines and their electrochemistry

3-[5-(diethylamino)-2-formylphenoxy]phthalonitrile ( n-TY-CN ), metallophthalocyanines n-TY-Co , n-TY-Cu , and n-TY-Mn bearing [5-(diethylamino)-2-formylphenoxy] groups at nonperipheral positions were prepared for the first time. These compounds were characterized with IR, NMR (only for n-TY-CN ), mass and UV-vis (except n-TY-CN ) spectroscopy. Voltammetric characterizations of n-TY-Co , n-TY-Cu , and n-TY-Mn revealed that while n-TY-Co , n-TY-Cu , and n-TY-Mn showed characteristic Pc ring and/or metal-based reduction reaction, n-TY-Co , n-TY-Cu , and n-TY-Mn were coated on the working electrode during the oxidation processes owing to the cationic electropolymerizations of the [5-(diethylamino)-2-formylphenoxy] substituents.     

Synthesis and copolymerization behavior of methacrylate dimers

Methacrylic ester-based dimers and oligomers were synthesized using a metal-based catalytic chain transfer agent. Conditions were employed which maximized the yield of unsaturated dimers, and the copolymerization behavior of these dimers was investigated. The molecular weight and polymer yield were found to decrease with increasing dimer concentration in the copolymerization feeds. © 1993 John Wiley & Sons, Inc.     

Removal of COD,aromaticity and color of a pretreated chemical producing industrial wastewater: a comparison between adsorption,ozonation, and advanced oxidation processes

A wide range of products are produced in the chemical producing industry such as textile dyes, chemicals, printing dyes and chemicals, paper chemicals, electrostatic powder dyes, and optical brighteners. The aim of this study is to investigate the treatability of chemical oxygen demand (COD), aromaticity, and color in the wastewater of this sector, where highly complex chemicals are used. Most of the studies in the literature are related to the treatment of synthetically prepared dyed wastewater. This study is important as it is carried out with real wastewater and gives results of many treatment methods. In the study, COD, UV-vis absorbance, and color values were attempted to be removed from the wastewater of a chemical producing industry that was pretreated by coagulation-flocculation. The COD value of the pretreated wastewater discharged to the central treatment system was restricted as 1000 mg/L. Pretreated wastewater characterization is as follows: COD: 2117 mg/L, UV-vis absorbance values at; 254 nm: 9.91, 280 nm: 8.65, 341 nm: 12.77, 436 nm: 5.01, 525 nm: 2.24, and 620 nm: 1.59. In the study, adsorption, ozonation, and advanced oxidation processes (Fenton and persulfate oxidation) were used to remove COD and UV-vis absorbance values (aromaticity, organics, and color). The method by which the best removal efficiency was obtained for all parameters was the adsorption process using powdered activated carbon (PAC). The equilibrium PAC dose was found as 6 g/L. At this adsorbent dose, the removal efficiencies of UV-vis absorbance values were all around 99% and the efficiency of COD removal was 77%. The Langmuir isotherm constants were found to be q_max= 30.4 mg/g and K_L = 487.9 (L/mg). The COD concentration at this adsorbent dose was 486 mg/L and wastewater was suitable for discharge to the central wastewater treatment plant in that region.     

AlSb-GaSb-InSb体系的研究

用区域致匀方法获得了AlSb-GaSb-InSb体系中均匀的合金。用X射线结构分析(粉末法)及差热分析研究了均匀化的样品。结果表明,在上述体系中有连续固溶体生成。确定了AlSb-GaSb-InSb体系液相面的投影图及AlSb·GaSb-InSb截面上组成与晶格参数间的关系,并比较了组成不同的合金在空气中的稳定性。     

Selfassembly of Metallic Nanoparticle Arrays by DNA Scaffolding

We report the self-assembly of metallic nanoparticle arrays using DNA crystals as a programmable molecular scaffolding. Gold nanoparticles, 1.4nm in diameter, are assembled in two-dimensional arrays with interparticle spacings of 4 and 64nm. The nanoparticles form precisely integrated components, which are covalently bonded to the DNA scaffolding. These results show that heterologous chemical systems can be assembled into precise, programmable geometrical arrangements by DNA scaffolding, thereby representing a critical step toward the realization of DNA nanotechnology.     

Pyrolysis—gas chromatography of normal human cells and amniotic fluid

Human cells derived from tissues and biological fluids have been characterized by pyrochromatography. Normal cells from the brain, kidney, liver and spleen of given individuals have been differentiated by their pyrochromatograms. Pyrochromatograms, are presented for cells from cultured skin fibroblasts which were obtained from cystic fibrotic individuals as well as those taken from disease-free individuals. Characteristic pyrochromatograms were also obtained from amniotic fluid.     

Sequence and structural duality: designing peptides to adopt two stable conformations

To improve our understanding of conformational transitions in proteins, we are attempting the de novo design of peptides that switch structural state. Here, we describe coiled-coil peptides with sequence and structural duality; that is, features compatible with two different coiled-coil motifs superimposed within the same sequence. Specifically, we promoted a parallel leucine-zipper dimer under reducing conditions, and a monomeric helical hairpin in an intramolecularly disulfide bridged state. Using an iterative process, we engineered peptides that formed stable structures consistent with both targets under the different conditions. Finally, for one of the designs, we demonstrated a one-way switch from the helical hairpin to the coiled-coil dimer upon addition of disulfide-reducing agents.     

Doubly charged ion mass spectra: III—N-alkanes

Doubly charged ion mass spectra have been obtained for 15 n-alkane hydrocarbons. Spectra were measured using a Nier-Johnson geometry Hitachi RMU-7L mass spectrometer operated at 1.6kV accelerating voltage. Fragment ions, which resulted from C? C bond rupture and extensive H loss, dominated the spectra. Molecular ions have not been observed. The most intense ions in the doubly charged ion mass spectra of n-alkanes were [C₂H₄]²⁺, [C₃H₂]²⁺, [C₄H₃]²⁺, [C₅H₂]²⁺, [C₆H₆]²⁺, [C₆H₈]²⁺, [C₇H₆]²⁺, [C₇H₈]²⁺, [C₈H₆]²⁺ and [C₈H₈]²⁺. Appearance energies for forming the prominent doubly charged fragment ions have been measured and range from 27.5 eV to energies greater than 60eV. A geometry optimized SCF approach has been used to compute the energies and structures of prominent ions in the doubly charged mass spectra.