Synthesis,Crystal Structure and Spectroscopic Properties of 1,2-Benzothiazine Derivatives:An Experimental and DFT Study

1,2-Benzothiazine derivatives methyl 3-methoxy-4-oxo-3,4-dihydro-2H-benzo[e] [1,2]thiazine-3-carboxylate 1,1-dioxide(1) and methyl 2-ethyl-3-hydroxy-4-oxo-3,4-dihydro-2Hbenzo[e][1,2]thiazine-3-carboxylate 1,1-dioxide(2) were synthesized, and characterized by spectroscopic techniques; 1H-NMR and infrared(IR) spectroscopy. Crystals of 1 and 2 were grown by slow evaporation of methanol and ethyl acetate, respectively and their crystal structures were investigated by single-crystal X-ray diffraction analysis. Geometric properties were calculated by the B3 LYP method of density functional theory(DFT) at the 6-31G+(d) basis set to compare with the experimental data. Simulated properties were found in strong agreement with the experimental ones. Intermolecular forces have also been modeled in order to investigate the strength of packing and strong hydrogen bonding was observed in both compounds 1 and 2. Electronic properties such as Ionization Potential(IP), Electron Affinities(EA) and coefficients of the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) of com- pounds 1 and 2 were simulated for the first time.     

Antihaemorrhagic potentials of Fagonia cretica against Naja naja karachiensis (black Pakistan cobra) venom

Plants have been extensively used as a remedy for the treatment of snake bites. The aim of this study was to determine the antivenom potentials of methanolic extract from the aerial parts (leaves and twigs) of Fagonia cretica L. on a haemorrhage induced by venom from Naja naja karachiensis. The haemorrhagic response of venom was dose dependent from 0.1 to 4.0?μg per 1.5?μL phosphate buffer saline (PBS) on vitelline veins of fertilised hens' eggs in their shells. The extract effectively eliminated and neutralised, in a dose-dependent manner, the haemorrhagic activity of snake venom. The minimum effective neutralising dose of F. cretica extract was found to be 15?μg per 1.5?μL PBS. The extract possesses potentials as haemorrhagic inhibitor against snake venom compared to the standard antiserum and various plants reported in the literature. This study also provides a scientific base for the use of F. cretica in traditional medicine for the treatment of snake bite.     

Synthesis,characterization, and antibacterial activities of copper(I) bromide complexes of thioureas: X-ray structure of [Cu(Metu)<Subscript>4</Subscript>]Br

Copper(I) complexes of thioureas having the general formulae [CuL_nBr] and [CuL_n]Br [where, n = 1 − 4 and L = thiourea (Tu), N-methylthiourea (Metu), N-ethylthiourea (Ettu), N,N^′-dipropylthiourea (Dprtu), N,N^′-dibutylthiourea (Dbtu) or N,N^′-diphenylthiourea (Dphtu)] were prepared and characterized by elemental analysis, IR, and NMR (¹H and ¹³C) spectroscopy. The crystal structure of one of them, [Cu(Metu)₄]Br (1), was determined by X-ray crystallography. The X-ray structure of 1 describes a tetrahedral geometry around copper(I) with all Metu ligands binding through sulfur atoms. An upfield shift in the ¹³C NMR and downfield shift in the ¹H NMR spectra are consistent with the thione coordination to copper(I). Antimicrobial activities of the complexes were evaluated by the minimum inhibitory concentration method. The results showed that only [Cu(Ettu)₃Br] was effective in inhibiting the growth of all the tested organisms (gram-positive, gram-negative bacteria, and Candida sp.), while the other complexes were not effective against all the organisms.     

Immobilizing Highly Catalytically Active Pt Nanoparticles inside the Pores of Metal-Organic Framework: A Double Solvents Approach

Ultrafine Pt nanoparticles were successfully immobilized inside the pores of a metal-organic framework, MIL-101, without aggregation of Pt nanoparticles on the external surfaces of framework by using a "double solvents" method. TEM and electron tomographic measurements clearly demonstrated the uniform three-dimensional distribution of the ultrafine Pt NPs throughout the interior cavities of MIL-101. The resulting Pt@MIL-101 composites represent the first highly active MOF-immobilized metal nanocatalysts for catalytic reactions in all three phases: liquid-phase ammonia borane hydrolysis, solid-phase ammonia borane thermal dehydrogenation, and gas-phase CO oxidation.     

Nucleation and crystal growth in sheared granular sphere packings

We investigate the nucleation of ordered phases, their symmetries, and distributions in dense frictional hard sphere packings as a function of particle volume fraction ?, by imposing cyclic shear and constant applied pressure conditions. We show, with internal imaging, that the nucleating crystallites in the bulk consist of 10-60 spheres with hexagonal close packed (hcp) order and nonspherical shape, that are oriented preferentially along the shear axis. Above ?=0.62±0.005, crystallites with face centered cubic (fcc) order are observed with increasing probability, and ordered domains grow rapidly. A polycrystalline phase with domains of fcc and hcp order is observed after hundreds of thousands of shear cycles.     

Synthesis,Biological Activity,and Molecular Docking Assessment of Some New Sulfonylated Tetrazole Derivatives

The designed molecular structures have been subjected to computational analysis for calculating their physicochemical properties and drug likeness. The calculated data indicate that most of the compound possess the bioactivity score in the active zone. Synthetic approach to the target compounds is straightforward and easy to handle. Structures of the new compounds are supported by FT-IR, ¹H, and ¹³C NMR, and mass spectra. Antimicrobial tests of the products against pathogens (S. aureus, S. epidermidis, E. coli, and P. mirabilis) indicate the products as active or highly active. Their cyto-toxicity is determined to be 92–98% at concentration of 3.125 µmol/L. The molecular docking analysis carried out for the target compounds against the receptor Glc-N-6P exhibits low binding energy and various binding sites of those.

     

Synthesis of Tapioca Cellulose-based Poly(amidoxime) Ligand for Removal of Heavy Metal Ions

Poly(acrylonitrile)/cellulose block copolymer (PAN-b-cell) was prepared by using a free radical initiating process and then the nitrile functional groups of the PAN blocks of the copolymers were transformed into amidoxime ligands. The resulting poly(amidoxime) ligands could complex with heavy metal ions; for example, the reflectance spectra of the [Cu -ligand]ⁿ⁺ was found to be at the highest absorbance, about 94%, at pH 6. The pH was the key parameter for metal ions sensing by the ligand. The adsorption capacity for copper was very good, 272 mg g^?1, with a fast adsorption rate (t_1/2 = 10 min). The adsorption capacities for other heavy metal ions such as Fe³⁺, Cr³⁺, Co³⁺ and Ni²⁺ were also good, being 242, 219, 201 and 195 mg g^?1, respectively, at pH 6. The heavy metal ions removal efficiency from water was 98% at low concentration. The data proved that the heavy metal ions adsorption onto the polymer ligands were well fitted with the Langmuir isotherm model (R²>0.99), which suggests that the cellulose-based adsorbent surface namely the poly(amidoxime) ligand, was homogenous and a monolayer. The reusability was examined by a sorption/desorption process for six cycles and the extraction efficiency was determined. This new adsorbent could be reused for 6 cycles without any significant loss in its original removal function.     

Efficient seed-mediated method for the large-scale synthesis of Au nanorods

Seed-mediated methods are widely followed for the synthesis of Au nanorods (NRs). However, mostly dilute concentrations of the Au precursor (HAuCl₄) are used in the growth solution, which leads to a low final concentration of NRs. Attempts of increasing the concentration of NRs by simply increasing the concentration of HAuCl₄, other reagents in the growth solution and seeds lead to a faster growth kinetics which is not favourable for NR growth. Herein, we demonstrate that the increase in growth kinetics for high concentrations of reagents in growth solution can be neutralised by decreasing the pH of the solution. The synthesis of the NRs can be scaled up by using higher concentrations of reagents and adding an optimum concentration of HCl in the growth solution. The concentration of HAuCl₄ in the growth solution can be increased up to 5 mM, and 10–20 times more NRs can be synthesised for the same reaction volume compared to that of the conventional seed-mediated method. We have also noticed that a cetyltrimethylammonium bromide (CTAB)-to-HAuCl₄ molar ratio of 50 is sufficient for obtaining high yield of NRs.     

Ion-Temperature-Gradient-Driven Modes with Nonthermal Electron Distributions in Bi-ion Dusty Magnetoplasma

The effect of nonthermal distributions of electrons on ion-temperature-gradient (ITG)-driven drift modes in the presence of tiny dust particles for bi-ion magneto plasmas is investigated. The dynamics of bi-ions and dust particles is considered for the study of low-frequency (less than the gyrofrequencies of dust and ions) ITG mode. A new dispersion relation is derived and analyzed numerically as well as analytically. Three different distributions for nonthermal electrons (Kappa, q, and Cairns distribution) are used. It is found that the presence of nonthermal electrons in bi-ion dusty magnetoplasma reduces the growth rate of the ITG instability. These results should be useful for laboratory and space plasmas where nonthermal electrons and dust is always present.     

Analysis on International Competitiveness of Service Trade in the Guangdong–Hong Kong–Macao Greater Bay Area Based on Using the Entropy and Gray Correlation Methods

Based on the analysis and measurement of the overall situation, import and export structure and international competitiveness of the various sectors of service trade in the Guangdong–Hong Kong–Macao Greater Bay Area, with the help of MATLAB and Gray System Modeling software, the synergy degree model was established to quantitatively analyze the synergy level of service trade in the Greater Bay Area with the help of grey correlation analysis method and entropy weight method. The results show that the overall development trend of service trade in the Guangdong–Hong Kong–Macao Greater Bay Area is good. The service trade industries in different regions are highly complementary and have a high degree of correlation. The potential for the coordinated development of internal service trade is excellent, and the overall situation of service trade in the Greater Bay Area is in a stage of transition from a moderate level of synergy to a high level of synergy. The Greater Bay Area can achieve industrial synergy by accelerating industrial integration and green transformation, establishing a coordinated development mechanism, sharing market platform, strengthening personnel security, and further enhancing the international competitiveness of service trade. The established model better reflects the current coordination of service trade in the Guangdong–Hong Kong–Macao Greater Bay Area and has good applicability. In the future, more economic, technological, geographic, and policy data and information can be comprehensively used to study the spatial pattern, evolution rules, and mechanisms of coordinated development in the broader area.