Effect of additives and precursor chemical structure on crystalline shape and optical properties of TiO2

This paper proposes a new simple approach for synthetic of shape-defined anatase nanocuboids TiO₂ by using combination of titanium tetra isopropoxide (TTIP) and orthotitanic acid (H₄TiO₄) as titanium precursor. In first step by adding precursor to ethanol solution mixed with HCl the primary sol has been prepared, therefore two other different films by adding Methylcellulose (MC) as a carbon containing material and adding TiO₂ nanopowder as nanofiller have been prepared and properties of thin film as a function of parameters of annealing temperature and additives, have been discussed. The films were deposited on glass substrates and characterized by using UV–vis spectroscopy and scanning electron microscopy (SEM). SEM results show that optical properties of TiO₂ thin films were changed by baking in 300, 400 and 500 °C as annealing temperature. Moreover, they indicate that the additives have strong effect on anatase structure and therefore influence the optical properties.     

{[K.18-Crown-6]Br3}n:保护胺和醇的三溴化催化剂（英文）

{[K.18-Crown-6]Br3}n , a unique tribromide-type catalyst, was utilized for the N-boc protection of amines and trimethylsilylation (TMS) and tetrahydropyranylation (THP) of alcohols. The method is general for the preparation of N-boc derivatives of aliphatic (acyclic and cyclic) and aromatic, and primary and secondary amines and also various TMS-ethers and THP-ethers. The simple separation of the catalyst from the product is one of the many advantages of this method.     

Composite Polymer/Oxide Hollow Fiber Contactors: Versatile and Scalable Flow Reactors for Heterogeneous Catalytic Reactions in Organic Synthesis

Flexible composite polymer/oxide hollow fibers are used as flow reactors for heterogeneously catalyzed reactions in organic synthesis. The fiber synthesis allows for a variety of supported catalysts to be embedded in the walls of the fibers, thus leading to a diverse set of reactions that can be catalyzed in flow. Additionally, the fiber synthesis is scalable (e.g. several reactor beds containing many fibers in a module may be used) and thus they could potentially be used for the large‐scale production of organic compounds. Incorporating heterogeneous catalysts in the walls of the fibers presents an alternative to a traditional packed‐bed reactor and avoids large pressure drops, which is a crucial challenge when employing microreactors.     

Influence of N+ ion implantation at different temperatures on nanostructural modifications and characteristics of Al alloy surface

Thick (3.0 mm) Al samples (7049 an alloy with 15 elements) were implanted by N⁺ ions of 30 keV energy and fluence of 5 × 10 ¹⁷ N⁺ cm^?2 at different temperatures. The surface modification of the samples was studied using X-ray diffraction (XRD) and atomic force microscope (AFM) analysis. XRD spectra of the samples clearly showed the formation of different phases of AlN. Crystallite sizes (coherently diffracting domains) obtained from AlN diffraction lines showed that at a certain substrate temperature the crystallite size decreases considerably. AFM images showed the formation of grains on Al samples, and it was observed that both grain size and sample surface roughness first decrease and then increase with temperature (i.e. a minimum at a certain temperature is observed). In addition at this temperature, a minimum of intensity is also observed for the intensity of different phases of AlN and the intensity ratio of AlN (200)/AlN (311). This phenomenon is similar to those obtained for thin films and pure metal foils though the sample studied in this work is an Al alloy and the minimum for Al occurred at a value three times larger than that reported for the above cases. Alloy nature of this sample with 14 elements is responsible for the observed results because they may act as defects. Results may also be affected by the residual gases, substrate temperature, dissociation of water in the chamber and the ion energy. Results also showed that the processes of Al nitride and Al oxide formations are competing with each other; decrease of aluminium nitride phases are associated with increase of aluminium oxide phases.     

Facile synthesis and biological assays of novel 2,4-disubstituted hydrazinyl-thiazoles analogs

A convenient, one-pot multi-component synthesis of new 2,4-disubstituted hydrazinyl-thiazoles was accomplished using different aldehydes/ketones, thiosemicarbazide, and 4-methoxy phenacyl bromide in the presence of a catalytic amount of AcOH in EtOH. Products were obtained in reasonable yields and high purity. The in vitro antioxidant activity of hydrazinyl-thiazoles was evaluated by DPPH radical scavenging activity in comparison to ascorbic acid. Synthesized thiazoles 14c and 14g possessed the lowest \(\hbox {IC}_{50}\) values. Also, hydrazinyl-thiazoles were screened for their in vitro antibacterial activity against six strains of bacteria including S. aureus, M. luteus, E. coli, Ps. aeruginosa, B. subtilis, and A. hydrophila where some products showed good antibacterial activity. Moreover, compound 14a showed anticancer activity against melanoma cancerous cell lines A375 with \(\hbox {LC}_{50}= 0.55\hbox { mg}/\hbox {mL}\), slightly selective versus normal cell lines (Hu-2) with \(\hbox {LC}_{50}= 1.19\hbox { mg}/\hbox {mL}\).     

Optimization of solid phase microextraction procedure for determination of paraquat using reduction process

Headspace solid phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry was developed for the determination of paraquat in urine. The volatile product resulting from reduction of paraquat by sodium borohydride–nickel chloride was used for HS-SPME. The calibration curve was linear from 10–1000 ng/mL and the limit of detection was 0.1 ng/mL. The optimized methods were validated using 500 and 750 ng/mL concentrations of paraquat in the spiked urine samples. The recoveries obtained in this study were 98.2% for intra-day (n = 6) and 99.2% for inter-day (n = 6), respectively, with RSD lower than 1.1%.     

Stripping voltammetric determination of copper(II) in natural waters and human hairs based on the adsorption of its complex with Kryptofix 22 on the carbon paste electrode

Traces of copper(II) can be determined by adsorptive stripping voltammetry using Kryptofix 22 as complex forming reagent. First, copper(II)-Kryptofix 22 complex was adsorbed on the carbon paste electrode in phosphate buffer pH 5.3 with an accumulation potential of −0.5 V. Following this, the adsorbed complex was oxidized and detected by anodic differential pulse voltammetric scan from −0.2 to 0.1 V. The effective parameters of sensor response were examined. The detection limit of copper(II) was 1.1 μg/L and relative standard deviations for 50 and 150 μg/L of Cu(II) were 1.2 and 0.96%, respectively. The calibration curve was linear for 2–150 μg/L of copper(II). This technique does not use mercury and therefore is environmentally beneficial. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amounts of copper(II) in water and human hair samples.     

Characterizing n-Isoclinism Classes of Lie Algebras

In this article, we introduce the notion of the equivalence relation, n-isoclinism, between Lie algebras, and obtain some criterions under which Lie algebras are n-isoclinic. In particular, we show that n-isoclinic Lie algebras can be isoclinically embedded into one Lie algebra. Also, we present the notion of an n-stem Lie algebra and prove its existence within an arbitrary n-isoclinism class. In addition, similar to a result of Hekster [6 Hekster , N. S. ( 1986 ). On the structure of n-isoclinam classes of groups . J. Pure Appl. Algebra 40 : 63 – 85 .[Crossref], [Web of Science ®] , [Google Scholar]] in the group case, we characterize the n-stem Lie algebras in the n-isoclinism classes which contains at least one finitely generated Lie algebra L with dim (L ⁿ⁺¹) finite.     

Improvement in IBC-silicon solar cell performance by insertion of highly doped crystalline layer at heterojunction interfaces

By inserting a thin highly doped crystalline silicon layer between the base region and amorphous silicon layer in an interdigitated back-contact(IBC) silicon solar cell, a new passivation layer is investigated. The passivation layer performance is characterized by numerical simulations. Moreover, the dependence of the output parameters of the solar cell on the additional layer parameters(doping concentration and thickness) is studied. By optimizing the additional passivation layer in terms of doping concentration and thickness, the power conversion efficiency could be improved by a factor of2.5%, open circuit voltage is increased by 30 mV and the fill factor of the solar cell by 7.4%. The performance enhancement is achieved due to the decrease of recombination rate, a decrease in solar cell resistivity and improvement of field effect passivation at heterojunction interface. The above-mentioned results are compared with reported results of the same conventional interdigitated back-contact silicon solar cell structure. Furthermore, the effect of a-Si:H/c-Si interface defect density on IBC silicon solar cell parameters with a new passivation layer is studied. The additional passivation layer also reduces the sensitivity of output parameter of solar cell to interface defect density.