Theoretical study on the effect of dopant positions and dopant density on transport properties of a BN co-doped SiC nanotube

We investigate the effect of dopant (boron ‘B’–nitrogen ‘N’) position and density on electronic transport properties of a BN co-doped silicon carbide nanotube (SiCNT). The results show an increase in conductance when both BN impurities are far in space from each other. Orbital delocalization and appearance of new electronic states around Fermi level contribute to the current when this spacing is increased. On the other hand, a reduction in SiCNT conductivity was observed when BN dopant density was increased. This is attributed to the electronic states moving away from the Fermi level and orbital localization at higher bias voltages.     

Styrene acrylonitrile (SAN) based polymeric waveguides

In the present study styrene acrylonitrile based polymeric waveguides have been optimized with the help of aging (variation of baking time keeping the temperature constant), annealing (variation of baking temperature keeping the time constant), concentration and thickness (physical). Propagation losses are lowest at an annealing temperature of 100°C and aging time of 8 h. The values of effective refractive index of the waveguides change inconsistently between 1.566 and 1.569 and between 1.5660 and 1.5667 for aging and annealing effect, respectively. However, by increasing the physical thickness of the film, the value of refractive index was decreased. By increasing the concentration of the solution, the refractive index of the waveguides was increased. The birefringence in the present observation is of the order of 10⁻⁴. Polarization selective properties were also observed in the present study for certain range of concentration.     

Solution-State 2D NMR Spectroscopy of Mixtures HyperpolarizedUsing Optically Polarized Crystals

The HYPNOESYS method (Hyperpolarized NOE System), which relies on the dissolution of optically polarized crystals, has recently emerged as a promising approach to enhance the sensitivity of NMR spectroscopy in the solution state. However, HYPNOESYS is a single-shot method that is not generally compatible with multidimensional NMR. Here we show that 2D NMR spectra can be obtained from HYPNOESYS-polarized samples, using single-scan acquisition methods. The approach is illustrated with a mixture of terpene molecules and a benchtop NMR spectrometer, paving the way to a sensitive, information-rich and affordable analytical method.     

Charge transfer complexes of picolines with sigma- and pi-acceptors

In the present study CT complexes of 2-, 3- and 4-Picolines with (DDQ) 2, 3-dichloro-5, 6-dicyano parabenzoquinone (pi-acceptor) and (I(2)) Iodine (sigma-acceptor) have been investigated spectrophotometrically in three different solvents (CCl(4), CHCl(3) and CH(2)Cl(2)) at six different temperatures. The formation constants of the CT complexes were determined by the Benesi-Hildebrand equation. The thermodynamic parameters were calculated by Van(')t Hoff equation. The DeltaH degrees , DeltaG degrees and DeltaS degrees values are all negative implying that the formation of studied complexes is exothermic in nature.     

Synthesis and Urease Inhibition Studies of Barbituric and Thiobarbituric Acid Derived Sulphonamides

Various novel barbituric and thiobarbituric acid derived sulphonamides were synthesized in excellent yield via three components single pot reaction; and these were screened for in vitro urease inhibition studies against jack bean urease. The compounds 1‐7 were found to exhibit a low to moderate activity whereas compounds 8‐14 showed a significant activity (88.3‐99.9% inhibition determined at 500 μM concentration). Structures of the synthesized compounds were confirmed by ¹H‐NMR, ¹³C‐NMR, mass spectrometry and elemental analysis data.     

Pd(OAc)2-Catalyzed Carbonylative Coupling of Aryl Iodide with Ortho-Haloamines in Water

The carbonylative cross coupling of aryl iodide with ortho-haloaniline to ortho-haloanilide using phosphine-free Pd(OAc)₂ catalyst in water as a reaction medium has been studied. The present protocol facilitated the reaction of o-haloanilines with a wide variety of hindered and functionalized aryl iodides, affording good yields of the desired products. The protocol was also extended for the synthesis of benzoxazoles through cyclization of ortho-haloanilide using Cu(acac)₂ catalyst.     

Synthesis, characterization and DNA binding studies of penta- and hexa-coordinated diorganotin(IV) 4-(4-nitrophenyl)piperazine-1-carbodithioates

Two chlorodiorganotin(IV) complexes with general formula R₂SnClL (R = n-C₄H₉(1) and C₂H₅(2) and a diphenyltin(IV) derivative with general formula Ph₂SnL₂(3), where L = 4-(4-nitrophenyl)piperazine-1-carbodithioate ligand, were prepared and characterized by elemental analysis, Raman, FT-IR, multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) and mass spectrometry. On the basis of spectroscopic data the effective coordination number of Sn atom was found five (1 and 2) and six (3) both in solution and solid state. Electrochemical, kinetic and thermodynamic parameters of complexes 1-3, interacting with DNA were evaluated by cyclic voltammetry. The linearity of the plots between the peak current (I) and the square root of the scan rate (ν^1/2) indicated the electrochemical processes to be diffusion controlled. The diffusion coefficients of the free (D_f) and DNA bound forms (D_b), standard rate constants (ks) and charge transfer coefficients (α) were determined by the application of Randle-Sevcik, Nicholson and Kochi equations. The values of binding constant and binding site size were evaluated from voltammetric data. The results revealed the following increasing order of binding strength: 1 (5.4 × 10³) < 3 (8.4 × 10³) < 2 (1.24 × 10⁴) M⁻¹. The UV-Vis spectroscopic data also indicated the same order of binding strength. Furthermore, the binding mode was suggested on the base of shift in peak potential (CV) and absorption maxima (UV-Vis spectroscopy).     

Fractionation of human serum lipoproteins and simultaneous enzymatic determination of cholesterol and triglycerides

A method based on Asymmetric Flow Field-Flow Fractionation (AF4) was developed to separate different types of lipoproteins from human serum. The emphasis in the method optimization was on the possibilities to characterize the largest lipoprotein fractions (LDL and VLDL), which is usually not possible with the size-exclusion chromatography methods applied in routine analysis. Different channel geometries and flow programs were tested and compared. The use of a short fractionation channel was shown to give less sample dilution at the same fractionation power compared to a conventional, long channel. Different size selectivities were obtained with an exponential decay and a linear cross flow program. The ratio of the UV absorption signal to the light scattering signal was used to validate the relation between retention time and size of the fractionated particles.An experimental setup was developed for the simultaneous determination of the cholesterol and triglycerides distribution over the lipoprotein fractions, based on enzymatic reactions followed by UV detection at 500 nm. Coiled and knitted PTFE tubing reactors were compared. An improved peak sharpness and sensitivity were observed with the knitted tubing reactor. After optimization of the experimental conditions a satisfactory linearity and precision (2-3% rsd for cholesterol and 5-6% rsd for triglycerides) were obtained. Finally, serum samples, a pooled sample from healthy volunteers and samples of sepsis patients, were analyzed with the method developed. Lipoprotein fractionation and cholesterol and triglyceride distributions could be correlated with the clinical background of the samples.     

Simultaneous Determination of Tranexamic Acid and Losartan Potassium in Dosage Formulations and Human Serum by RP-LC

Rapid liquid chromatographic procedure for analytical quality control of pharmaceutical preparations and human serum containing drugs, tranexamic acid together with losartan potassium are proposed, using acetonitrile: water (50:50), adjusting pH to 2.6 with phosphoric acid as a mobile phase, UV detection at 205 nm and propylparaben sodium was used as internal standard. The results obtained showed a good agreement with the declared contents. The method shows good linearity in the range of 40–10,000 ng mL^?1 for tranexamic acid serum concentrations with a correlation coefficient 0.9999 (inter- and intra-day CV <3.18) and in the range 5–10,000 ng mL^?1 for losartan potassium serum concentrations with a correlation coefficient 0.9999 (inter- and intra-day CV <3.61). The recovery was >97.8%. The proposed method may be used for the quantitative analysis of tranexamic acid and losartan potassium alone or in combination from raw materials, in bulk drugs, dosage formulations and in serum.