Long-wavelength Ultraviolet A1 and Visible Light Photoprotection: A Multimodality Assessment of Dose and Response

Human skin is exposed to visible light (VL; 400–700 nm) and long-wavelength ultraviolet A1 (UVA1) radiation (370–400 nm) after the application of organic broad-spectrum sunscreens. The biologic effects of these wavelengths have been demonstrated; however, a dose–response has not been investigated. Ten subjects with Fitzpatrick skin phototype IV-VI were enrolled. Subjects were irradiated with 2 light sources (80–480 J cm⁻²): one comprising VL with less than 0.5% UVA1 (VL+UVA1) and the other pure VL. Skin responses were evaluated for 2 weeks using clinical and spectroscopic assessments. 4-mm punch biopsies were obtained from nonirradiated skin and sites irradiated with 480 J cm⁻² of VL+UVA1 and pure VL 24 h after irradiation. Clinical and spectroscopic assessments demonstrated a robust response at VL+UVA1 sites compared with pure VL. Histology findings demonstrated a statistically significant increase in the marker of inflammation (P < 0.05) and proliferation (P < 0.05) at the irradiated sites compared with nonirradiated control. Threshold doses of VL+UVA1 resulting in biologic responses were calculated. Results indicate that approximately 2 h of sun exposure, which equates to VL+UVA1 dose (~400 J cm⁻²), is capable of inducing inflammation, immediate erythema and delayed tanning. These findings reinforce the need of photoprotection beyond the UV range.     

An investigation on the influence of the shape of the vortex generator on fluid flow and turbulent heat transfer of hybrid nanofluid in a channel

Journal of Thermal Analysis and Calorimetry - The purpose of this study is to numerically investigate flow field and turbulent heat transfer of hybrid nanofluid, water–DWCNT–TiO2 in a...     

Two building blocks of microwave photonics filters in the presence of group delay ripple: a comparative survey

We have developed an analytic approach to investigate the effect of group delay ripple of the dispersive devices on the performance of two major building blocks of microwave-photonic filters. Firstly, performance of PM-based block in the presence of an arbitrary group delay ripple (GDR) is analyzed and compared with the ripple-free case to reveal the destructive effects of added group delay ripple. In the next step, we repeat the proposed approach for the AM-based one; again, the performance is compared with the ripple-free case. Two distortion metrics are also introduced to quantify this distortion. Comparison of the performance of two building blocks in the presence of group delay ripple unveils some interesting characteristics of microwave-photonic filters which have not been mentioned so far. We also add a general survey of two analyzed building blocks to present their respective most significant advantages and shortcomings. The simulated Optisystem results conform to our proposed analytical approach and verify the theoretical model.     

Competitive solvent extraction of alkaline earth metals by ionizable nano-baskets of calixarene

The competitive solvent extraction of alkaline earth metals using different nano-baskets was investigated. The novelty of this work is to study the correlations between the isomer structure of calixarenes and their extraction properties. The objective was to quantify the effects of aryl groups in the ionisable pendant moieties, calixarene conformation, steric orientations (cis- and trans-) and relative positions (ortho- and para-) of pendant moieties upon the extraction efficiency, pH_1/2 and the selectivity of calix[4]arene complexes. Alkaline earth metals were extracted from aqueous solutions into chloroform by di-ionisable calix[4]arenes and were measured using ion chromatography. The results revealed that alternation of aryl group in the pendant moieties, changing their orientation from cis- to trans-analogues as well as from ortho- to para- analogues, showed no changes in the selectivity, the extraction efficiency and the pH_1/2 of calix[4]arene complexes. Changing the scaffold of calixarene's ring to the cone, 1,2-alternate and partial-cone conformers altered their complexation ability towards alkaline earth metals and their extraction efficiency.     

Preconcentration and determination of methyl methacrylate by dispersive liquid–liquid microextraction

This article describes the preconcentration of methyl methacrylate in produced water by the dispersive liquid–liquid microextraction using extraction solvents lighter than water followed by gas chromatography. In the present experiments, 0.4 mL dispersive solvent (ethanol) containing 15.0 μL extraction solvent (toluene) was rapidly injected into the samples and followed by centrifuging and direct injection into the gas chromatograph equipped with flame ionization detector. The parameters affecting the extraction efficiency were evaluated and optimized including toluene (as extraction solvent), ethanol (as dispersive solvent), 15 μL and 0.4 mL (as the volume of extraction and dispersive solvents, respectively), pH 7, 20% ionic strength, and extraction's temperature and time of 20°C and 10 min, respectively. Under the optimum conditions, the figures of merits were determined to be LOD = 10 μg/L, dynamic range = 20–180 μg/L, RSD = 11% (n = 6). The maximum recovery under the optimized condition was determined to be 79.4%.     

Synthesis of 2‐Aryl‐5‐oxo‐4‐[2‐(phenylmethylidene)hydrazino]‐2,5‐dihydro‐1H‐pyrrole‐3‐carboxylates by the Reaction between Hydrazones,Acetylenedicarboxylates, and 1‐Aryl‐N,N′‐bis(arylmethylidene)methanediamines

An efficient approach for the preparation of functionalized 2‐aryl‐2,5‐dihydro‐5‐oxo‐4‐[2‐(phenylmethylidene)hydrazino]‐1H‐pyrroles is described. The four‐component reaction between aldehydes, NH₂NH₂?H₂O, dialkyl acetylenedicarboxylates, and 1‐aryl‐N,N′‐bis(arylmethylidene)methanediamines proceeds in EtOH under reflux in good‐to‐excellent yields (Scheme 1). The structures of 4 were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS, and, in the case of 4f , by X‐ray crystallography). A plausible mechanism for this type of reaction is proposed (Scheme 2).     

Application of 1H NMR in the flow surveillance of oil wells

Test‐separator units, as traditional methods of well surveillance, mainly suffer from their inherent constraints including the expensive instrumental, mechanical, electrical, piping and safety devices along with technical and protective inspections, repair and operation services, facilities and infrastructures. Other problems are time and cost consuming, uncertainty of well isolation in test separator and need to close the co‐line wells, which are diminished using multivariate thermal well testing. A novel approach was proposed and tested to classify the oil samples taken from individual wells by source and type. The novelties of this work were the use of the applied aspects of ¹H NMR spectroscopy in petroleum upstream engineering, the replacement of traditional test methods, the improvement of the confidence of tests and the recognition of multisource streams. The weighed sum method was used to correlate the spectra information, taken from the samples of Iranian offshore oil wells. The experimental results and the field data revealed that the present approach was appropriate for precocious, quick and reliable surveillance of individual oil wells located in an oil field. The model was supported by field experiments and has predicted the accurate productivity of oil wells with respect to the current expensive techniques since 2010. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparative study of kinetic modeling for the oxidative coupling of methane by genetic and marquardt algorithms

Overall kinetic studies on the oxidative coupling of methane, OCM, have been conducted in a tubular fixed bed reactor, using perovskite titanate as the reaction catalyst. The appropriate operating conditions were found to be: temperature 750-775 ℃, total feed flow rate of 160 ml/min, CH4/O2 ratio of 2 and GHSV of 100 min-1. Under these conditions, C2 yield of 28% was achieved. Correlations of the kinetic data have been performed with lumped rate equations for C2 and COx formation as functions of temperature, O2 and CH4 partial pressures. Six models have been selected among the common lumped kinetic models. The selected models have been regressed with the experimental data which were obtained from the Catatest system by genetic algorithm in order to obtain optimized parameters. The kinetic coefficients in the overall reactions were optimized by different numerical optimization methods such as: the Levenberg-Marquardt and genetic algorithms and the results were compared with one another. It has been found that the Santamaria model is in good agreement with the experimental data. The Arrhenius parameters of this model have been obtained by linear regression. It should be noted that the Marquardt algorithm is sensitive to the first guesses and there is possibility to trap in the relative minimum.