Synthesis of cyclobutenyl ketals

A series of dialkoxy derivatives of N,N\u27-di-tert-butyl-2-butylamino-3,3-dichloro-4-dichloromethylene cyclobutenyl carboxamidinum chloride, were prepared by dissolving either Na+ or K+ alkoxide in the appropriate alcohol, or by treatment with potassium hydroxide in the appropriate alcohols. Thus, the dimethoxy, diethoxy, di-isopropoxy, di-n-butoxy, di-tertbutoxy derivatives were obtained

Radiation Analysis and Characteristics of Conformal Reflectarray Antennas

This paper investigates the feasibility of designing reflectarray antennas on conformal surfaces. A generalized analysis approach is presented that can be applied to compute the radiation performance of conformal reflectarray antennas. Using this approach, radiation characteristics of conformal reflectarray antennas on singly curved platforms are studied and the performances of these designs are compared with planar designs. It is demonstrated that a conformal reflectarray antenna can be a suitable choice for applications requiring high-gain antennas on curved platforms

SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF SOFOSBUVIR AND DACLATASVIR IN PURE AND DOSAGE FORMS

Objective: Two simple, sensitive and accurate spectrophotometric methods have been developed for the determination of sofosbuvir (SOF) and daclatasvir (DAC) in pure forms and pharmaceutical formulations. Methods: The proposed methods are based on the oxidation of SOF and DAC by a known excess of cerium(IV) ammonium nitrate in sulphuric acid medium followed by determination of unreacted cerium(IV) by adding a fixed amount of indigo carmine (IC) and alizarin red S (ARS) dyes followed by measuring the absorbance at 610 and 360 nm, respectively. The experimental conditions affecting the reaction were studied and optimized. Results: The beer’s law was obeyed in the concentration ranges of 0.2-3.0, 0.2-4.0 for SOF and 0.5-4.5 and 0.5-5.0 μg/ml for DAC using IC and ARS methods, respectively with a correlation coefficient ≥ 0.9991. The calculated molar absorptivity values are 2.354 × 104, 1.933 × 104 for SOF and 1.786 × 104 and 2.015 × 104 L/mol. cm for DAC using IC and ARS methods, respectively u. The limits of detection and quantification are also reported. Intra-day and inter-day precision and accuracy of the methods have been evaluated. Conclusion: The methods were successfully applied to the assay of SOF and DAC in tablets and the results were statistically compared with those of the reference method by applying Student’s t-test and F-test. No interference was observed from the common tablet excipients. The accuracy and reliability of the methods were further ascertained by performing recovery studies using the standard addition method

A Two-Dimensional Single-Field FDTD Formulation for Oblique Incident Electromagnetic Simulations

Abstract A set of general purpose two-dimensional single-field finite-difference time-domain updating equations for solving oblique incidence electromagnetic problems is derived. The traditional FDTD updating equations are based on Maxwell's curl equations whereas the single-field FDTD updating equations are based on the vector wave equation. Performance analyses of the single-field formulation in terms of CPU time and memory requirement are presented along with numerical validation. It was observed that the single-field method is more efficient than the traditional FDTD formulation in terms of speed and memory requirements for oblique incident problems

A Novel Tunable Triple-Band Left-Handed Metamaterial

A novel tunable triple-band left-handed metamaterial (LHM) composed of a single-loop resonator (SLR) and a variable capacitor-loaded short wire pair (CL-SWP) printed on both sides of a substrate is presented in this paper. The CL-SWP-based metamaterial (MTM) is a novel single-sided LHM. It is theoretically analyzed capable of extracting tunable negative permeability and a wide-band negative permittivity. We ran simulations for the CL-SWP-based MTM, the SLR-based MTM, and the proposed LHM. Together with the measured results, it is identified that this novel LHM exhibits a tunable triple-band left-handed (LH) property. With the increase of the loaded capacitance, one LH band is relatively stable, while the other two are moving towards lower frequencies with their bandwidth getting wider and narrower, respectively. The surface current density distributions indicate that the first LH band is mainly decided by the SLR, one of the rest 2 LH bands is mainly decided by the CL-SWP, and the other one is decided by the SLR and CL-SWP together

Synergistic Factors Affecting Catalytic Performance of Fe(II) Phthalocyanine @ Titania-Pillared Bentonite Nanocomposites in Styrene Production

The hybrid nanocatalytic system under study consisted of iron (II) phthalocyanine complex (FePc) of 0.5 – ~10 wt % loading immobilized in the bentonite interlayers modified by pillaring with titania nanoparticles (88 nm). Various interactions facing FePc complex were discussed through the changes in different characteristics assessed by adopting XRD, FTIR, ICP-EDX, TGA-DrTGA, TEM, N2 adsorption-desorption and H2-chemisorption techniques. Intercalated FePc molecules could evolve excessive silanol and aluminol sites through interaction with various clay-interlayer sites and titania pillar. By applying this FePc @ Ti-PILB nanocomposite in oxidative dehydrogenation of ethyl benzene, synergistic combination of factors influencing selective production of styrene confirmed the optimum turnover frequency with maximum selectivity to styrene at 3.4 wt % FePc loading. Below this loading, redox pair factor linked with dispersion and orientation mode of FePc was predominating. In higher loaded samples of considerable silanol sites, clay acid-base pair balance became prevailing

Tailoring the deposition of MoSe2 on TiO2 nanorods arrays via radiofrequency magnetron sputtering for enhanced photoelectrochemical water splitting

MoSe2/1 D TiO2 nanorods (NRs) heterojunction assembly was systematically fabricated, and its photoelectrocatalytic properties were investigated. The fabrication process involves the growth of 1D TiO2 NRs arrays on FTO substrates using hydrothermal synthesis followed by the deposition of MoSe2 nanosheets on the TiO2 NRs using radiofrequency magnetron sputtering (RF magnetron sputtering). The photoelectrochemical properties of the heterojunction were explored and optimized as a function of the thickness of the MoSe2 layer, which was controlled by the sputtering time. The MoSe2 grows perpendicularly on TiO2 NRs in a 2D layered structure, maximizing the exposed active edges, an essential aspect that permits maximum exploitation of deposited MoSe2. Compared to pure TiO2 NRs, the heterojunction nanostructured assembly displayed excellent spectral and photoelectrochemical properties, including more surface oxygen vacancies, enhanced visible-light absorption, higher photocurrent response, and decreased charge transfer resistance. In particular, the sample synthesized by sputtering of MoSe2 for 90 s, i.e., MoSe2@TiO2-90 s, depicted the highest current density (1.86 mA cm−2 at 0.5 V vs. Ag/AgCl) compared to other samples. The excellent photoelectrochemical activity of the heterojunction stemmed from the synergy between tailored loading of MoSe2 nanosheets and the 1D structure of TiO2 NRs, which afford a high surface/volume ratio, effective charge separation, fast electron transfer, and easy accessibility to the MoSe2 active edges. These factors boost the catalytic activity.This work was made possible by NPRP Grant no. NPRP 12S-0304-190218 from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. Open Access funding provided by the Qatar National Library.Scopu

Combined effect of steel fibres and steel rebars on impact resistance of high performance concrete

The investigation on the impact properties of normal concrete (NC)and reinforced concrete (RC) specimens, steel fibre reinforced concrete (SFRC) specimens and RC+SFRC specimens with different steel fibres dosages were carried out with the drop-weight impact test recommended by ACI Committee 544. The results indicate that the number of blows to final failure greatly increased by addition of steel fibres. Moreover, the combination of steel fibres and steel rebars demonstrates a significant positive composite effect on the impact resistance, which results on the improvement in impact toughness of concrete specimens. In view of the variation of impact test results, the two-parameter Weibull distribution was adopted to analyze the experimental data. It is proved that the probabilistic distribution of the blows to first crack and to final failure of six types of samples are approximately two-parameter Weibull distribution.Funded by the National Natural Science Foundation of China (NSFC) (Grant No.50578026)Financial support provided by the Research Center of Mathematics of the University of Minho through the FCT Pluriannual Funding Progra

Transcriptomic and metabolic responses of Calotropis procera to salt and drought stress

Background: Calotropis procera is a wild plant species in the family Apocynaceae that is able to grow in harsh, arid and heat stressed conditions. Understanding how this highly adapted plant persists in harsh environments should inform future efforts to improve the hardiness of crop and forage plant species. To study the plant response to droμght and osmotic stress, we treated plants with polyethylene glycol and NaCl and carried out transcriptomic and metabolomics measurements across a time-course of five days. Results: We identified a highly dynamic transcriptional response across the time-course including dramatic changes in inositol signaling, stress response genes and cytokinins. The resulting metabolome changes also involved sharp increases of myo-inositol, a key signaling molecule and elevated amino acid metabolites at later times. Conclusions: The data generated here provide a first glimpse at the expressed genome of C. procera, a plant that is exceptionally well adapted to arid environments. We demonstrate, through transcriptome and metabolome analysis that myo-inositol signaling is strongly induced in response to drought and salt stress and that there is elevation of amino acid concentrations after prolonged osmotic stress. This work should lay the foundations of future studies in adaptation to arid environments

Analysis of transcriptional response to heat stress in Rhazya stricta

Clusters of assembled transcripts of R. stricta SRA in mature leaves (A5-L8) at different time points of the day (A, morning; F-H, midday & L, dusk). Grey lines indicate expression patterns of individual transcripts in a given cluster. Blue lines indicate overall expression pattern across different transcripts of a given cluster. (PDF 397 kb