The synthesis and characterization of 2-(2′-pyridyl)benzimidazole heteroleptic ruthenium complex: Efficient sensitizer for molecular photovoltaics

The novel ligand 1-(2,4,6-trimethylbenzyl)-2-(2′-pyridyl)benzimidazole and its heteroleptic ruthenium (II) complex were synthesized. The complex was characterized using spectroscopic methods and cyclic voltammetry. Charge-separation was investigated within nanoporous titanium dioxide employing surface photovoltage spectroscopy. The performance of the ruthenium complex as a charge transfer photosensitizer in nanocrystalline, titanium dioxide-based, dye sensitized solar cells was studied under standard AM 1.5 sunlight using an electrolyte consisting of 0.6 M 1-butyl-3-methyl-imidazolium iodide, 0.1 M lithium iodide, 0.05 M iodine and 0.5 M 4-tert-butyl pyridine in 3-methoxy propyonitrile. The novel complex had a photocurrent density of 9.47 mA cm⁻², 600 mV open circuit potential and 0.60 fill factor yielding an efficiency of 3.4%. The photovoltaic performance of the colorant was compared with that of cis-bis(isothiocyanato)(2,2'-bipyridyl-4,4'-dicarboxylato) (2,2’-bipyridyl-4,4’-di-nonyl) ruthenium(II); both compounds exhibited similar efficiency, while the fill factor value was higher for the novel dye.     

Surface and wetting characteristics of textured bisphenol‐A based polycarbonate surfaces: Acetone‐induced crystallization texturing methods

Polycarbonate (PC) sheet is a promising material for facile patterning to induce hydrophobic self‐cleaning and dust repelling properties for photovoltaic panels’ protection. An investigation to texture PC sheet surfaces to develop a self‐cleaning structure using solvent induced‐crystallization is carried out using acetone. Acetone is applied in both liquid and vapor states to generate a hierarchically structured surface that would improve its contacts angle and therefore improve hydrophobicity. The surface texture is investigated and characterized using atomic force microscopy, contact angle technique (Goniometer), optical microscopy, ultraviolet‐visible spectroscopy (UV–vis) and Fourier transform infrared spectroscopy. The findings revealed that the liquid acetone‐induced crystallization of PC surface leads to a hierarchal and hydrophobic surface with an average contact angle of 135° and average transmittance <2%. However, the acetone vapor induced‐crystallization results in a slightly hydrophilic hierarchal textured surface with high transmittance; in which case, average contact angle of 89° and average transmittance of 69% are achieved. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43074.     

Synthesis, electrorheology and creep behavior of polyindole/polyethylene composites

In this study, polyindole (PIN) and polyindole/polyethylene (PIN/PE) conducting composites, having various amounts of PIN, were synthesized by chemical polymerization using FeCl₃ as an oxidizing agent and taking the ratio of salt:monomer as 3:1. The samples of PIN and PIN/PE composites were characterized by FTIR, UV–vis, TGA, SEM, Gouy scale magnetic susceptibility, conductivity (1.2 × 10⁻³ S cm⁻¹ > σ > 1.96 × 10⁻⁶ S cm⁻¹, at T = 25 °C) and density measurements. FTIR analysis suggested a 2,3-propagation mechanism for PIN formation. The ground milled samples were subjected to particle size analysis by dynamic light scattering (DLS) and a micron-sized particle distribution was obtained. A series of volume fractions ( = 10–25%) were prepared from the materials in silicone oil (SO) and their sedimentation stabilities determined. The most stable composite [PIN(89%)/PE(11%)] against gravitational sedimentation was subjected to flow-rate measurements under externally applied electric field strength (E) and an electrorheological (ER) activity was observed; threshold energies (E_t) were calculated. The effects of volume fraction, shear rate, external E, frequency and temperature onto ER activities of the suspensions were investigated. Enhancement in the electric field viscosities and shear thinning viscoelastic behaviors were observed for all the samples studied. Recoverable viscoelastic deformations were determined from the creep tests under external E.     

New (κ-C,N)-palladacyclic complexes with benzimidazol-2-ylidene ligand: Synthesis, crystal structures and characterization

Reaction of unsymmetrical benzimidazolium bromides (1) with Ag₂O and subsequent transmetallation with chloro-bridged dinuclear palladacycle, [Pd(dmba)(μ-Cl)]₂ (dmba: N,N-dimethylbenzylamine) afforded benzannulated monocarbene complexes [Pd(dmba)(NHC)Cl], 2. The palladacycles (2a–c) were characterized by elemental analysis; NMR spectroscopy and the molecular structure of 2a and 2c were determined by X-ray crystallography.     

Value of ovarian stromal blood flow velocity measurement after pituitary suppression in the prediction of ovarian responsiveness and outcome of in vitro fertilization treatment

BACKGROUND: The fatty acid composition of the diet is known to be partially reflected by the fatty acid composition of serum lipids. OBJECTIVE: We examined whether pentadecanoic acid (15:0) in serum lipids can be used as a marker for intake of milk fat, the major dietary source of 15:0. We also investigated the relations between intake of milk fat and cardiovascular disease risk factors. DESIGN: Sixty-two 70-y-old men completed 7-d dietary records. The intake of milk products was studied in relation to the proportions of 15:0 in serum cholesterol esters and phospholipids, as well as to the clinical characteristics of these men, by using Spearman's rank correlation. RESULTS: The proportions of 15:0 in serum cholesterol esters were positively related to butter intake (r = 0.36. P = 0.004) and to the total amount of fat from milk products (r = 0.46, P < 0.0001): 15:0 in phospholipids was related to the amount of fat from milk and cream (r = 0.34, P = 0.008) and to the total amount of fat from milk products (r = 0.34, P = 0.008). Inverse associations were found between intake of milk products and body mass index, waist circumference, LDL-HDL ratio, HDL triacylglycerols, and fasting plasma glucose, whereas relations to HDL cholesterol and apolipoprotein A-I tended to be positive. CONCLUSIONS: The results suggest that 15:0 in serum can be used as a marker for intake of milk fat. The explanation for the inverse associations between the intake of milk products and certain cardiovascular risk factors is not known.     

Synthesis,electrorheology, and creep behaviors of in situ intercalated polyindole/organo‐montmorillonite conducting nanocomposite

In this study, first polyindole (PIN) was synthesized using FeCl₃ as an oxidizing agent. Then, an organo‐montmorillonite (O‐MMT) was prepared from virgin montmorillonite (MMT) by cetyltrimethylammonium bromide (CTAB) quaternary ammonium salt. Further, PIN/O‐MMT conducting nanocomposite was prepared with 18% O‐MMT content. The samples of PIN, MMT, O‐MMT, and PIN/O‐MMT nanocomposite were characterized by FTIR spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction (XRD), elemental analysis, conductivity, magnetic susceptibility, density, particle size measurements, and scanning electron microscopy (SEM) method. Characterization results showed a successfully prepared PIN/O‐MMT nanocomposite having both intercalated and exfoliated structures. A series of concentrations (5–25%, m/m) were prepared from those above‐mentioned materials in silicone oil (SO) and their sedimentation stabilities were determined. The suspensions were subjected to an external electric field strength and electrorheological (ER) activity was observed. The effects of dispersed particle concentration, shear rate, external electric field strength, frequency, and temperature onto ER activities of these suspensions were investigated. Creep tests were applied to all the four suspensions and recoverable viscoelastic deformations observed. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Improvement of the Intergranular Pinning Energy in the (BiPb)2Sr2Ca2Cu3O10+δ Superconductors Doped with High Valancy Cations

In the present work, Bi?CPb?CV?CSr?CCa?CCu?CTi?CO bulk samples with nominal composition (BiPb)₂V _x Sr₂Ca₃Cu_4?y Ti _y O_12+?? with x=0.1 and y=0.050, 0.10, 0.2, and 0.3 have been prepared by the melt-quenching method. The magnetoresistance of the samples has been measured for different values of the applied magnetic field. The thermally activated flux creep model has been studied in order to calculate the flux pinning energies. The flux pinning energies calculated increase with increasing Ti-content, and decrease with applied magnetic field.     

The Exp-function Method for Some Time-fractional Differential Equations

In this article, the fractional derivatives in the sense of modified Riemann-Liouville derivative and the Exp-function method are employed for constructing the exact solutions of nonlinear time fractional partial differential equations in mathematical physics. As a result, some new exact solutions for them are successfully established. It is indicated that the solutions obtained by the Exp-function method are reliable, straightforward and effective method for strongly nonlinear fractional partial equations with modified Riemann-Liouville derivative by Jumarie's. This approach can also be applied to other nonlinear time and space fractional differential equations.      

Laser heating mechanism including evaporation process initiating laser drilling

A laser heating mechanism initiating the drilling process is examined. The study includes conduction and convection effects and assumes a steady-state evaporation process. This enables estimation of the limits of the Fourier theory in laser drilling applications. Using the model described in the analysis, maximum temperature attained inside the material, nucleation, explosion process and drilling efficiency are predicted. The results obtained from the present work for the vapor front velocity are compared to those obtained from previous experiments. In addition, a laser drilling experiment is carried out while monitoring the surface evaporation process. This enables correlation of the theoretical results with the experiments.     

Laser welding of Haynes 188 alloy sheet: thermal stress analysis

Laser welding of Haynes 188 alloy sheets is carried out. Temperature and stress fields developed in the welding section are predicted numerically incorporating the finite element algorithm. The microstructural changes in the welding region are examined using the optical and electron scanning microscopes. The microhardness variation across the weld zone is measured and associated with the residual stress formed in this region. It is found that the microhardness follows the residual stress distribution in the weld core. The maximum residual stress is less than the elastic limit of the substrate material.