Facile electrochemical growth of nanostructured copper phthalocyanine thin film via simultaneous anodic oxidation of copper and dilithium phthalocyanine for photoelectrochemical hydrogen evolution

We present a novel electrochemical approach to grow copper phthalocyanine (CuPc) thin-film photoelectrodes through anodic oxidation of copper and dilithium phthalocyanine (Li₂Pc). This circumvents the challenges associated with the electrochemical processing of unsubstituted CuPc from solution. The potentiostatic co-electrooxidation reaction at the heterogeneous interface favors the growth of CuPc thin film. The surface morphology of thin film exhibits nanorod-like features. UV-Vis, grazing angle Fourier transform infrared (FTIR), and grazing angle X-ray diffraction patterns reveal that the nanocrystalline phase corresponds only to α-CuPc and no admixture of other polymorphs. Photocurrent measurement shows a stable photoresponse in neutral medium. The photoelectrochemical hydrogen evolution on p-type CuPc coated copper photocathode shows an enhanced activity over bare copper and indium tin oxide (ITO) electrodeposited with CuPc and monolithium phthalocyanine radical (LiPc) thin films.     

Anomalous Aharonov-Bohm conductance oscillations from topological insulator surface states

We study Aharonov-Bohm (AB) conductance oscillations arising from the surface states of a topological insulator nanowire, when a magnetic field is applied along its length. With strong surface disorder, these oscillations are predicted to have a component with anomalous period Φ(0)=hc/e, twice the conventional period. The conductance maxima are achieved at odd multiples of 1/2Φ(0), implying that a π AB phase for electrons strengthens the metallic nature of surface states. This effect is special to topological insulators, and serves as a defining transport property. A key ingredient, the surface curvature induced Berry phase, is emphasized here. We discuss similarities and differences from recent experiments on Bi2Se3 nanoribbons, and optimal conditions for observing this effect.     

Study on γ-ray exposure buildup factors and fast neutron-shielding properties of some building materials

We have computed γ-ray exposure buildup factors (EBF) of some building materials; glass, marble, flyash, cement, limestone, brick, plaster of paris (POP) and gypsum for energy 0.015–15 MeV up to 40 mfp (mfp, mean free path) penetration depth. Also, the macroscopic effective removal cross-sections (Σ_R) for fast neutron were calculated. We discussed the dependency of EBF values on photon energy, penetration depth and chemical elements. The half-value layer and kinetic energy per unit mass relative to air of building materials were calculated for assessment of shielding effectiveness. Shielding thicknesses for glass, marble, flyash, cement, limestone and gypsum plaster (or Plaster of Paris, POP) were found comparable with ordinary concrete. Among the studied materials limestone and POP showed superior shielding properties for γ-ray and neutron, respectively. Radiation safety inside houses, schools and primary health centers for sheltering and annual dose can be assessed by the determination of shielding parameters of common building materials.     

Optimal utilization of service facility for ak-out-of-n system with repair by extending service to external customers in a retrial queue

In this paper, we study ak-out-of-n system with single server who provides service to external customers also. The system consists of two parts: (i) a main queue consisting of customers (failed components of thek-out-of-n system) and (ii) a pool (of finite capacityM) of external customers together with an orbit for external customers who find the pool full. An external customer who finds the pool full on arrival, joins the orbit with probability γ and with probability 1- γ leaves the system forever. An orbital customer, who finds the pool full, at an epoch of repeated attempt, returns to orbit with probability δ (< 1) and with probability 1- δ leaves the system forever. We compute the steady state system size probability. Several performance measures are computed, numerical illustrations are provided.     

Noise correlations in one-dimensional systems of ultracold fermions

Time of flight images reflect the momentum distribution of the atoms in the trap, but the spatial noise in the image holds information on more subtle correlations. Using bosonization, we study such correlations in generic 1D systems of ultracold fermions. We show how pairing as well as spin and charge density wave correlations may be identified and extracted from time of flight images. These incipient orders manifest themselves as power-law singularities in the noise correlations, that depend on the Luttinger parameters, which suggests a general experimental technique to obtain them.     

Spin phonon induced collinear order and magnetization plateaus in triangular and kagome antiferromagnets: applications to CuFeO2

We study the effect of spin-lattice coupling on triangular and kagome antiferromagnets and find that even moderate couplings can induce complex collinear orders. On coupling classical Heisenberg spins on the triangular lattice to Einstein phonons, a rich variety of phases emerge including the experimentally observed four sublattice state and the five sublattice 1/5th plateau state seen in the magnetoelectric material CuFeO(2). Also, we predict magnetization plateaus at 1/3, 3/7, 1/2, 3/5, and 5/7 at these couplings. Strong spin-lattice couplings induce a striped collinear state, seen in alpha-NaFeO(2) and MnBr(2). On the kagome lattice, moderate spin-lattice couplings induce collinear order, but an extensive degeneracy remains.     

Topological spin liquid on the hyperkagome lattice of Na4Ir3O8

Recent experiments on the "hyperkagome" lattice system Na4Ir3O8 have demonstrated that it is a rare example of a three-dimensional spin-1/2 frustrated antiferromagnet. We investigate the role of quantum fluctuations as the primary mechanism lifting the macroscopic degeneracy inherited by classical spins on this lattice. In the semiclassical limit we predict, based on large-N calculations, that an unusual q[over -->]=0 coplanar magnetically ordered ground state is stabilized with no local zero modes that correspond to local deformations of the spin configurations. This phase melts in the quantum limit and a gapped topological Z2 spin liquid phase emerges. In the vicinity of this quantum phase transition, we study the dynamic spin structure factor and comment on the relevance of our results for future neutron scattering experiments.     

Modulation instability of incoherent beams in noninstantaneous nonlinear media

We show that modulation instability can exist with partially spatially incoherent light beams in a noninstantaneous nonlinear environment. For such incoherent modulation instability to occur, the value of the nonlinearity has to exceed a threshold imposed by the degree of spatial coherence.     

Inhibition of testicular and Vipera russelli snake venom hyaluronidase activity by Butea monosperma (Lam) Kuntze stem bark

This study was carried out to investigate the anti-fertility and anti-venom activities of the extract of the stem bark of Butea monosperma by inhibiting hyaluronidase, which is a spreading factor and plays a role in fertilisation. Among ethanol, methanol and water extracts, the ethanol extract dose-dependently inhibited the ovine, mouse testicular and Vipera russelli snake venom hyaluronidase enzyme activities, with IC?? values 12.00?±?0.45, 49.40?±?1.58?μg and 125.42?±?2.82?μg?mL?1, respectively. In a zymogram assay, the extract showed differential inhibition towards hyaluronidase isoform preferentially with low-molecular weight isoforms. The V. russelli snake venom-induced hemorrhage was significantly reduced at 1:05 ratio of venom-to-extract in mouse. The high antioxidant activity and total phenolic content in the ethanolic extract strongly correlated with the hyaluronidase inhibition. The above results justify the traditional use of the stem bark of B. monosperma as a contraceptive and a strong antidote to snake venom.