Thermodynamic properties of a magnetically modulated graphene monolayer

The effect of magnetic modulation on thermodynamic properties of a graphene monolayer in the presence of a constant perpendicular magnetic field is reported here. One-dimensional spatial electric or magnetic modulation lifts the degeneracy of the Landau levels and converts into bands and their bandwidth oscillates with magnetic field, leading to Weiss-type oscillations in the thermodynamic properties. The effect of magnetic modulation on the thermodynamic properties of a graphene sheet is studied and then compared with electrically modulated graphene and magnetically modulated conventional two-dimensional electron gas (2DEG). We observe Weiss-type and de Haas-van Alphen oscillations at low and high magnetic fields, respectively. There is a definite phase difference in Weiss-type oscillations in thermodynamic quantities of magnetically modulated graphene compared to electrically modulated graphene. On the other hand, the phase remains the same and the amplitude of the oscillation is large when compared with the magnetically modulated two-dimensional electron gas (2DEG). Explicit asymptotic expressions of the density of states and the Helmholtz free energy are provided to understand the phase and amplitude of the Weiss-type oscillations qualitatively. We also study thermodynamic properties when both electric and magnetic modulations are present. The Weiss-type oscillations still exist when the modulations are out-of-phase.     

Synthesis and biological activity of substituted 3-fluoro/3-trifluoromethyl 10H-phenothiazines, its ribofuranosides and sulfones

The present article describes the synthesis of new fluorinated 10H-phenothiazines by Smiles rearrangement. The reaction of these synthesized phenothiazines with sugar (beta-d-ribofuranose 1-acetate-2,3,5-tribenzoate) afforded the new ribofuranosides and the oxidation of these synthesized phenothiazines with 30% hydrogen peroxide in glacial acetic acid resulted in the formation of 10H-phenothiazine sulfones. These compounds were evaluated for their antioxidant and antimicrobial activities (using broth microdilution method). The structural assignments of the synthesized compounds were made on the basis of elemental analysis and spectroscopic data.     

Sequential coupling/desilylation-coupling/cyclization in a single pot under Pd/C-Cu catalysis: synthesis of 2-(hetero)aryl indoles

A new one-pot synthesis of 2-(hetero)aryl indoles via sequential C-C coupling followed by C-Si bond cleavage and a subsequent tandem C-C/C-N bond forming reaction is described. A variety of functionalized indole derivatives were prepared by conducting this four step reaction under Pd/C-Cu catalysis. The methodology involved coupling of (trimethylsilyl)acetylene with iodoarenes in the presence of 10% Pd/C-CuI-PPh(3) and triethylamine in MeOH, followed by treating the reaction mixture with K(2)CO(3) in aqueous MeOH, and finally coupling with o-iodoanilides. The single crystal X-ray data of a synthesized indole derivative is presented. Application of the methodology, in vitro pharmacological properties of the synthesized compound, along with a docking study is described.     

Effect of Microwave Irradiation on Xylanase Production from Wheat Bran and Biobleaching of Eucalyptus Kraft Pulp

Microwave irradiation (MWI) was used as pretreatment of wheat bran and eucalyptus kraft pulp to examine its effect on xylanase production by Bacillus halodurans FNP 135 using solid state fermentation and biobleaching with xylanase, respectively. Irradiation of wheat bran under optimized conditions (600?W, 6?min, and 20?% consistency) resulted in 56.8, and 31.7?% increase in xylanase yield and water absorbance of wheat bran and 17.3?% reduction in reducing sugars content. Optimized MWI of kraft pulp at 850?W, 2?min, and 20?% consistency led to 0.9?% increase in brightness, 10?% decrease in kappa number, 7.7?% increase in water absorbance, 4.6?% decrease in tear factor, 0.9?% increase in burst factor, and 7.5?% increase in viscosity. Also, MWI enhanced xylanase-mediated biobleaching by increasing brightness (1.1?%) and decreasing kappa number (14.3?%) and leading to a total of about 20?% reduction in chlorine consumption. MWI is an economical, efficient, and environment-friendly pretreatment of wheat bran and pulp for enhanced enzyme yield and rapid heating, respectively.     

Stereoselective synthesis of cis- or trans-2,4-disubstituted butyrolactones from Wynberg lactone

(R)-Wynberg lactone was used to prepare various asymmetric 2,4-disubstituted butyrolactones in three to four steps. Attainment of any possible stereoisomer, based upon commencement from (R)- or (S)-4-trichloromethyl-2-oxetanone, and the capacity to install disparate substituents at C₂ make this approach particularly versatile.     

Crystal and Molecular Structure Studies of 1′-Benzyl-8-(4-fluorobenzyl)-8-azaspiro[bicyclo-[3.2.1]octane-3,4′-imidazolodine]-2′,5′-dione

Abstract  

The title compound, C₂₃H₂₃FN₃O₂ has been synthesized and the structure was investigated by X-ray diffraction studies. The compound crystallizes in the triclinic crystal class in the space group P[`1]P\overline{1} with cell parameters a = 9.345(2) ?, b = 10.940(3) ?, c = 11.986(4) ?, α = 72.349(6)°, β = 68.106(18)°, γ = 66.867(5)°, Z = 2 and V = 1027.8(5) ?³. The hydantoin ring adopts a planar conformation and is affected by the π conjugation. The pyrrolidine and piperidine rings in the bicyclo octane moiety adopt envelope and chair conformations respectively. The structure exhibits both inter and intramolecular hydrogen bonds of the type N–H···O, C–H···O and C–H···N. One of the oxygen atoms attached to the hydantoin ring simultaneously accepts two hydrogen bonds to form a three centered hydrogen bonding pattern.     

Non‐linear interaction of a q‐Gaussian laser beam in a plasma channel created by the ignitor‐heater technique

This paper presents a theoretical investigation of the propagation characteristics of a q‐Gaussian laser beam propagating through a plasma channel created by the ignitor‐heater technique. The ignitor beam creates the plasma by tunnel‐ionization of air. The heater beam heats the plasma electrons and establishes a parabolic channel. The third beam (q‐Gaussian beam) is guided in the plasma channel under the combined effects of density non‐uniformity and non‐uniform ohmic heating of the plasma channel. Numerical solutions of the non‐linear Schrodinger wave equation (NSWE) for the fields of laser beams are obtained with the help of the moment theory approach. Particular emphasis is placed on the dynamical variations of the spot size of the laser beams and the longitudinal phase shift of the guided beam with the distance of propagation.     

Optical modelling of P3HT:PC<Subscript>71</Subscript>BM semi-transparent organic solar cell

The optical properties of a novel semi-transparent organic solar cell were investigated both experimentally and by transfer matrix modelling to maximize photocurrent generation. The effect of multilayer anode thickness and illumination direction was studied. Bottom illumination was shown to provide enhanced exciton generation and increased photocurrent. Changing the multilayer anode thickness also influenced the device reflectance and photocurrent generation.     

B ?→ K 1*? (1270)(→ ρ 0 K ?) ? + ? ? in LEET

Flavor changing neutral current (FCNC) decays of the B-meson are a very useful tool for studying possible physics scenarios beyond the standard model (SM), where of the many FCNC modes radiative, purely leptonic and semi-leptonic decays of the B-meson are relatively clean tests. Within this context, the BELLE collaboration has measured the process B→K ^* γ and also searched for the B→K ₁(1270)γ process. Theoretical analyses of these processes are yielding similar values of the relevant form factors. In this work we have used this upper bound in studying the angular correlations for the related semi-leptonic decay mode B ⁻→K ₁⁻(1270)(→ρ ⁰ K ⁻)ℓ ⁺ ℓ ⁻, where we have used the form factors that have already been estimated for the B→K ₁(1270)γ mode. Note that the additional form factors that are required were calculated using large energy effective theory (LEET).