A capable neural network model for solving the maximum flow problem

This paper presents an optimization technique for solving a maximum flow problem arising in widespread applications in a variety of settings. On the basis of the Karush–Kuhn–Tucker (KKT) optimality conditions, a neural network model is constructed. The equilibrium point of the proposed neural network is then proved to be equivalent to the optimal solution of the original problem. It is also shown that the proposed neural network model is stable in the sense of Lyapunov and it is globally convergent to an exact optimal solution of the maximum flow problem. Several illustrative examples are provided to show the feasibility and the efficiency of the proposed method in this paper.     

Catalytic aromatization of Hantzsch 1,4-dihydropyridines by ferric perchlorate in acetic acid

Catalytic oxidation of Hantzsch 1,4-dihydropyridines is described using a catalytic amount of ferric perchlorate in acetic acid at room temperature.     

<Emphasis Type="Italic">glpX</Emphasis> Gene of <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis>: Heterologous Expression,Purification, and Enzymatic Characterization of the Encoded Fructose 1,6-bisphosphatase II

The glpX gene (Rv1099c) of Mycobacterium tuberculosis (Mtb) encodes Fructose 1,6-bisphosphatase II (FBPase II; EC 3.1.3.11); a key gluconeogenic enzyme. Mtb possesses glpX homologue as the major known FBPase. This study explored the expression, purification and enzymatic characterization of functionally active FBPase II from Mtb. The glpX gene was cloned, expressed and purified using a two step purification strategy including affinity and size exclusion chromatography. The specific activity of Mtb FBPase II is 1.3 U/mg. The enzyme is oligomeric, followed Michaelis–Menten kinetics with an apparent km = 44 μM. Enzyme activity is dependent on bivalent metal ions and is inhibited by lithium and inorganic phosphate. The pH optimum and thermostability of the enzyme have been determined. The robust expression, purification and assay protocols ensure sufficient production of this protein for structural biology and screening of inhibitors against this enzyme.     

A practical and highly efficient synthesis of densely functionalized nicotinonitrile derivatives catalyzed by zinc oxide‐decorated superparamagnetic silica attached to graphene oxide nanocomposite

Zinc oxide‐decorated superparamagnetic silica attached to graphene oxide (Fe₃O₄/SiO₂/PTS‐GO‐ZnO), as a novel nanocomposite, was designed, and its core‐shell structure was appropriately characterized by different spectroscopy or microscopy methods and thermal techniques as well as measuring of its porosity and magnetic properties. The catalytic activity of Fe₃O₄/SiO₂/PTS‐GO‐ZnO, as a reusable heterogeneous catalyst, was investigated for efficient one‐pot multi‐component synthesis of medicinally important functionalized 2‐amino‐6‐(2‐oxo‐2H‐chromen‐3‐yl)‐4‐arylnicotinonitrile derivatives. The significant features of the present procedure are mild reaction conditions, low loading of the catalyst, high to quantitative yields of the desired products, avoiding the use of toxic heavy metals or solvents, simple isolation and purification of the products, and stability as well as reusability of the catalyst after at least six consecutive runs.     

An efficient method for synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds in the presence of sodium dodecyl sulfate in aqueous media

Stable crystalline phosphorus ylides and 1,4-diionic organophosphorus compounds were obtained in good to excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and β-dicarbonyl or heterocyclic compounds, such as diethyl malonate, acetyl acetone, 1,3-diphenyl propane-1,3-dione, 1,3-dimethylbarbituric acid, meldrum’s acid, 2-benzoxazolinone, benzotirazole, and 2-thiazoline-2-thiol in the presence of sodium dodecyl sulfate as a surfactant in water. Green synthesis, mild conditions, decreasing timescale of reaction, low cost, and easy workup are the main advantages of this method.     

Iron(III) phosphate catalyzed synthesis of 1,4-dihydropyridines

Novel 1,4-dihydropyridines (1,4-DHPs) are prepared efficiently via Hantzsch reaction using aldehydes, benzylacetoacetate and catalytic amount of iron(III) phosphate under solvent-free conditions in good yields.     

Two new phosphinic amides: Synthesis,crystal structure,and theoretical study of hydrogen bonding

Two novel phosphinic amides, (C₆H₅)₂P(O)(NH?cyclo?C₇H₁₃) (I) and (C₆H₅)₂P(O)(NH?cyclo?C₆H₁₁) (II) were synthesized and characterized by spectroscopic methods and X-ray crystallography. Both compounds crystallize in the orthorhombic chiral space group P2₁2₁2₁ and in both structures, the N—H···O hydrogen bonds lead to one-dimensional arrangements along the a axis. The molecular geometries and vibrational frequencies of I and II were investigated with quantum chemical calculations at the B3LYP/6–311G^** level of theory. Furthermore, the hydrogen bonds were studied by means of the Bader theory of atoms in molecules (AIM) and natural bond orbital (NBO) analysis.     

Assessment of Effects of Concomitant Exposure to Sound,Heat, and Physical Workload Changes on Physiological Parameters in Five Different Combination Modes,a Controlled Laboratory Study

Exposure to sound, heat, and increased physical workload can change physiological parameters. This study was conducted to evaluate the effect of concomitant exposure to sound, heat, and physical workload changes on physiological parameters in controlled laboratory conditions. This experimental crosssectional study was conducted in 35 male university students with a mean age of 25.75 years and a mean BMI of 22.69 kg/m² . Systolic and diastolic blood pressure and heart rate were measured after 15 min rest in the laboratory, 5 and 10 min after starting the experiment, and then after 20 min in controlled laboratory conditions in five combination modes. The combination modes were (Sound: 65 dB, WBGT: 22°C, Speed: 1.7, Slope: 10%), (Sound: 65 dB, WBGT: 22°C, Speed: 3.4, Slope: 14%), (Sound: 95 dB, WBGT: 22°C, Speed: 1.7, Slope: 10%), (Sound: 65 dB, WBGT: 32°C, Speed: 1.7, Slope: 10%), and (Sound: 95 dB, WBGT: 32°C, Speed: 3.4, Slope: 14%). Mixed model analysis and paired t-test were applied for analysis. The results showed that the mean physiological parameters (Systolic and diastolic blood pressure and heart rate) increased when different combination modes worsened (Sound from 65 to 95 dB, WBGT from 22°C to 32°C, speed from 1.7 to 3.4, and slope from 10% to 14%, and when sound: 95 dB, WBGT: 32°C, Speed: 3.4, and Slope: 14%). Moreover, the mean changes of systolic and diastolic blood pressure were significant in all conditions when compared with the reference condition (Sound: 65 dB, WBGT: 22°C, Speed: 1.7, and Slope: 10%). The mean heart rate changes were also significant except for exposure to the second condition (Sound: 65 dB, WBGT: 22°C, Speed: 3.4, Slope: 14%) and the third condition (Sound: 95 dB, WBGT: 22°C, Speed: 1.7, Slope: 10%). Exposure to hazardous levels of sound, heat, and workload has adverse effects on physiological parameters. Concomitant exposure to all three hazards has a synergistic effect and increases the adverse effect.     

Effects of iridium content on the physical,microstructure, and assay of gold alloys during the cupellation process

The aim of the present study is developing a simple, commercially available, and inexpensive method for detecting the presence of Ir in gold alloys during the cupellation process to avoid errors in gold assays. In the presence of Ir, the reported gold karat is higher than its actual amount. It is, therefore, economically important to detect Ir in gold alloys because of its lower price than gold. The present study was implemented to investigate the effects of Ir in a gold alloy both on its assay during the cupellation process and on its appearance and microstructural transformations. Visual inspection revealed that the upper surface of Ir-containing beads is typically matte and coarse with black rough cavities of an irregular oval-like shape. Also, the observation of dark spots and lines on just one side of rolled beads, as well as blister-like appendages on parted and annealed cornets, were found to signify the presence of Ir in gold alloys. X-ray analysis along the vertical section of the bead indicated that the amount of Ir on the surface was negligible as it was mainly concentrated at a distance of about 75% from the top of the bead. After the parting and annealing steps, Ir forms cubic-like structures surrounded by fcc Au sponge-like structures. As a consequence, both visual and microstructural examinations of gold alloys during the cupellation process might be used as simple and useful strategies to identify the presence of Ir in gold alloys to prevent incorrect karat reports.