Electrochemical behavior of isoproterenol in the presence of uric acid and folic acid at a carbon paste electrode modified with 2,7-bis(ferrocenyl ethyl)fluoren-9-one and carbon nanotubes

This paper reports the selective determination of isoproterenol (IP) in the presence of uric acid (UA) and folic acid (FA) using 2,7-bis(ferrocenyl ethyl)fluoren-9-one modified carbon nanotube paste electrode (2,7-BFCNPE) in 0.1 M phosphate buffer solution (PBS) (pH 7.0). The bare carbon paste electrode does not separate the voltammetric signals of IP, UA, and FA. However, 2,7-BFCNPE not only resolved the voltammetric signals of IP, UA, and FA with potential differences of 150, 325, and 475 mV between IP–UA, UA–FA, and IP–FA, respectively, but also dramatically enhanced the oxidation peak currents of them when compared to bare carbon paste electrode. In PBS of pH 7.0, the oxidation current increased linearly with two concentration intervals of IP, one is 0.08 to 17.5 μM and the other is 17.50 to 700.0 μM. The detection limit (3σ) obtained by DPV was 26.0 ± 2 nM. The practical application of the modified electrode was demonstrated by determining IP in IP injection, urine, and human blood serum.     

Effects of substrate on surface morphology, crystallinity, and photoluminescence properties of sputtered ZnO nano films

Effects of substrate on crystallinity, surface morphology, and luminescence properties of radio frequency sputtered zinc oxide (ZnO) thin films were investigated. A variety of materials such as Si (100), Si (111), Al₂O₃, quartz, and silicon carbide (SiC) wafers were examined as substrates for deposition of ZnO thin films. The results showed smooth and uniform growth of c-axis orientation films. The thickness of the layers was about 50 nm. The average grain sizes of films were about 10, 13, and 12 nm for Si (111), quartz, and SiC samples, respectively. The deposited film on Al₂O₃ showed the largest grain size, about 500 nm. Grazing incidence x-ray diffraction patterns of the samples revealed that sputtered layers on Al₂O₃ and quartz had better crystallinity with higher peak at (002) orientation compared to Si and SiC substrates. Moreover, the Al₂O₃ sample exhibited a weak peak at position of (100) planes of ZnO too. The photoluminescence spectra of the samples showed a typical luminescence behavior with a broad UV band, including a main peak at around 388 nm and a weak shoulder peak at around 381 nm, corresponding with bound excitonic recombination and free excitonic recombination, respectively. The luminescence peak revealed that the intensity of UV emission is not necessarily dependent on the grain sizes and the micro-structural quality of ZnO films.     

A new branch and bound algorithm for cell formation problem

Cell formation (CF) is the first and the most important problem in designing cellular manufacturing systems. Due to its non-polynomial nature, various heuristic and metaheuristic algorithms have been proposed to solve CF problem. Despite the popularity of heuristic algorithms, few studies have attempted to develop exact algorithms, such as branch and bound (B&B) algorithms, for this problem. We develop three types of branch and bound algorithms to deal with the cell formation problem. The first algorithm uses a binary branching scheme based on the definitions provided for the decision variables. Unlike the first algorithm, which relies on the mathematical model, the second one is designed based on the structure of the cell formation problem. The last algorithm has a similar structure to the second one, except that it has the ability to eliminate duplicated nodes in branching trees. The proposed branch and bound algorithms and a hybrid genetic algorithm are compared through some numerical examples. The results demonstrate the effectiveness of the modified problem-oriented branch and bound algorithm in solving relatively large size cell formation problems.     

Glivenko theorems and negative translations in substructural predicate logics

Along the same line as that in Ono (Ann Pure Appl Logic 161:246–250, 2009), a proof-theoretic approach to Glivenko theorems is developed here for substructural predicate logics relative not only to classical predicate logic but also to arbitrary involutive substructural predicate logics over intuitionistic linear predicate logic without exponentials QFL _e . It is shown that there exists the weakest logic over QFL _e among substructural predicate logics for which the Glivenko theorem holds. Negative translations of substructural predicate logics are studied by using the same approach. First, a negative translation, called extended Kuroda translation is introduced. Then a translation result of an arbitrary involutive substructural predicate logics over QFL _e is shown, and the existence of the weakest logic is proved among such logics for which the extended Kuroda translation works. They are obtained by a slight modification of the proof of the Glivenko theorem. Relations of our extended Kuroda translation with other standard negative translations will be discussed. Lastly, algebraic aspects of these results will be mentioned briefly. In this way, a clear and comprehensive understanding of Glivenko theorems and negative translations will be obtained from a substructural viewpoint.     

High temperature oxidation resistance and corrosion properties of dip coated silica coating by sol gel method on stainless steel

Silica coating for the protection of stainless steel (SS) surfaces was prepared using tetraethoxysilane and methyltriethoxysilane as precursors via an acid-catalysed (H₂SO₄) sol?Cgel method and was deposited on ferritic SS AISI 430 by dip coating. The surface morphology was studied using a scanning electron microscope equipped with energy-dispersive X-ray, phase analysis was carried out by X-ray diffraction, and isothermal oxidation was carried out at 800?°C for 200?h. Corrosion properties were examined by electrochemical impedance spectroscopy and resistance polarization methods in an aqueous medium containing 3.5?wt?% NaCl. The results indicated that silica coating improved high-temperature oxidation resistance of AISI 430 in chloride media.     

Base-catalyzed three-component direct Mannich reaction of enolizable ketones with high syn-selectivities

The three-component direct Mannich reaction between aldehydes, p-toluenesulfonamide, and enolizable ketones was achieved for the first time with organic bases as the catalysts. The corresponding N-tosylated β-aminoketones were obtained in high yields and good to excellent diastereoselectivities using TMG as the catalyst. Through reduction of the ketone group, the reaction product may be converted into β-aminol with excellent diastereoselectivity.     

Nonlinear Analysis and Optimum Design of Guyed Masts

In this paper the nonlinear analysis and design optimization of guyed masts is addressed. The mast is modeled as a 3D truss and is supported by catenary cable elements that have nonlinear elastic behavior. For nonlinear static analysis, an innovative procedure is proposed that divides the structure into linear and nonlinear parts and analyzes them separately. The proposed method satisfies the equilibrium and compatibility by establishing and solution of a set of nonlinear equations. The optimization problem employs the sizes of members, initial cable tensions and the positions of anchor on the ground and tie level of cables on the mast as design variables. To facilitate the optimization solution, a compatible sensitivity analysis procedure is proposed. Sensitivities of objective function, displacement and strength constraints in the mast and cables, subjected to a variety of load combinations including dead, wind and ice loads are calculated. Numerical examples are provided to show the nonlinear analysis procedure and the applicability of the algorithm to optimum design of practical guyed masts.     

Synthesis and characterization of two new fluorescent macrocycles: A novel fluorescent chemosensor for zinc ion

Two new macrocyclic systems (L¹, L²) containing two emissive naphthalene were synthesized and characterized. The macrocycles were studied by ¹H NMR, ¹³C NMR, COSY, HMQC, DEPT, microanalysis and mass spectroscopy. The influence of metal cations Na⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Hg²⁺ on the spectroscopic properties of the macrocyclic systems in acetonitrile/DMF 9:1 (v/v) mixtures were investigated by means of absorption and emission spectrophotometry. The macrocycle L¹ was found to be as an effective fluorescence sensor for Zn²⁺ ions. Zn²⁺ and Cd²⁺ ions show the most effects on the fluorescence intensity of L².     

Atomic Force Microscopy and X‐Ray Photoelectron Spectroscopy of Lead(II) Membrane Electrode Based on Dithiodibenzoic Acid as Ionophore

The use of 1‐butyl‐3‐methylimidazolium hexafluorophosphate ionic liquid [C₄mim][PF₆] as additive in a Pb(II) plastic membrane electrode increased significantly the selectivity of the sensor. Atomic force microscopy and depth profiling X‐ray photoelectron spectroscopy were applied to investigate the compositional and morphological changes of the surface and bulk of the membrane during the conditioning process of the electrode.