Conditions for magnetically induced singlet d-wave superconductivity on the square lattice

It is expected that at weak to intermediate coupling, d-wave superconductivity can be induced by antiferromagnetic fluctuations. However, one needs to clarify the role of Fermi surface topology, density of states, pseudogap, and wave vector of the magnetic fluctuations on the nature and strength of the induced d-wave state. To this end, we study the generalized phase diagram of the two-dimensional half-filled Hubbard model as a function of interaction strength $U/t$, frustration induced by second-order hopping $t^{\prime}/t$, and temperature $T/t$. In experiment, $U/t$ and $t^{\prime}/t$ can be controlled by pressure. We use the two-particle self-consistent approach (TPSC), valid from weak to intermediate coupling. We first calculate as a function of $t^{\prime}/t$ and $U/t$ the temperature and wave vector at which the spin response function begins to grow exponentially.D-wave superconductivity in a half-filled band can be induced by such magnetic fluctuations at weak to intermediate coupling, but only if they are near commensurate wave vectors and not too close to perfect nesting conditions where the pseudogap becomes detrimental to superconductivity. For given $U/t$ there is thus an optimal value of frustration $t^{\prime}/t$ where the superconducting $T_c$ is maximum. The non-interacting density of states plays little role. The symmetry d$_{x^{2}-y^{2}}$ vs d$_{xy}$ of the superconducting order parameter depends on the wave vector of the underlying magnetic fluctuations in a way that can be understood qualitatively from simple arguments

Chemical Characteristics of Pyrolysis Liquid Smoke Some Types of Woodsmoke

Liquid smoke can be used to preserve and add to the taste of food. The quality of liquid smoke is determined by the type of wood smoke used. This study aimed to evaluate the yield and chemical composition of the liquid smoke made from wood kandis, wood Laban, Ubar wood and coconut shell. The fourth type of timber is made of liquid smoke with condensation method using a pyrolysis. Parameters danalisis consists of the chemical composition of wood, the yield of liquid smoke, phenols, acids, pH, carbonyl and antioxidants. The results showed that wood Laban has a higher value on the total carbonyl is 15:43% and the value of the antioxidant is 84.26%

Effects of Thermal Shock on Mechanical Behaviour of Kevlar Fibre Composites

The development of composite technology represents one of the most significant advances in materials science since 1940s. The major advantages of composite materials are their high strength and stiffness, light weight, corrosion resistance, crack and fatigue resistance and design flexibility as compared to metallic materials. Because of the attractive properties. the use of composite materials has been increasing steadily in recent years. Unfortunately, there are disadvantages in composite materials as compared with metals. They include brittleness, vulnerability to stress concentration, inflexibility for localised multidirectional stresses, sensitivity to environmental effects, and poor damage tolerance to impact. These factors must be critically considered in designing a composite system. The aramid keviar family of fibres have been accepted as reinforcement for composites and finds wider and newer applications in various industrial and aerospace sectors. The interfacial bond strength between aramid fibres and epoxy resins is normally lower than what is experienced with carbon fibre composites. This weakness with kevlar necessitates investigation and evaluation of the interlaminar shear strength (ILSS) and modulus under some realistic environmental conditions. The present work has been taken up to evaluate the variation of ILS S and modulus values after being given the extreme thermal shock of 160°C thermal gradient. The thermal shock is given in two separate ways, firstly, one series of kevlar/ epoxy and kevlar/polyester short beam shear (SBS) specimens are kept in a oven at 80°C for different time intervals and then immersed in a liquid bath at -80`'C temperature. The other experiment is done in reverse way i.e. first kept at -80°C and then exposed to 80°C temperature. The interesting variations of ELSS and modulus values have generated some ideas for assessment in this area. The thermal shock, positive temperature and cryogenic temperature affect the kevlar/epoxy and kevlar/polyester composites in a very complex way. The wide fluctuation in results necessitates further investigation and depth analysis of this interaction, It may be hypothesised that the extreme thermal shock may introduce some decohesion between fibre/matrix interface especially when the gradient is positive in thermal shock

Zero Temperature Insulator-Metal Transition in Doped Manganites

We study the transition at T=0 from a ferromagnetic insulating to a ferromagnetic metallic phase in manganites as a function of hole doping using an effective low-energy model Hamiltonian proposed by us recently. The model incorporates the quantum nature of the dynamic Jahn-Teller(JT) phonons strongly coupled to orbitally degenerate electrons as well as strong Coulomb correlation effects and leads naturally to the coexistence of localized (JT polaronic) and band-like electronic states. We study the insulator-metal transition as a function of doping as well as of the correlation strength U and JT gain in energy E_{JT}, and find, for realistic values of parameters, a ground state phase diagram in agreement with experiments. We also discuss how several other features of manganites as well as differences in behaviour among manganites can be understood in terms of our model.Comment: To be published in Europhysics Letter

Pulsar Prospects for the Cherenkov Telescope Array

In the last few years, the Fermi-LAT telescope has discovered over a 100 pulsars at energies above 100 MeV, increasing the number of known gamma-ray pulsars by an order of magnitude. In parallel, imaging Cherenkov telescopes, such as MAGIC and VERITAS, have detected for the first time VHE pulsed gamma-rays from the Crab pulsar. Such detections have revealed that the Crab VHE spectrum follows a power-law up to at least 400 GeV, challenging most theoretical models, and opening wide possibilities of detecting more pulsars from the ground with the future Cherenkov Telescope Array (CTA). In this contribution, we study the capabilities of CTA for detecting Fermi pulsars. For this, we extrapolate their spectra with "Crab-like" power-law tails in the VHE range, as suggested by the latest MAGIC and VERITAS results.Comment: 4 pages, 3 figures. In Proceedings of the 2012 Heidelberg Symposium on High Energy Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184

Antibacterial Susceptibility and Resistance Pattern of Organisms Isolated from Rectal Swab of Chicken

Resistance to antibiotics is a serious matter of concern for Public and threats to the successful treatment of miscrobial disease. The prevalence of some enterobacteriaceae such as Escherichia coli and Salmonella spp resistant to antimicrobial agents is increasing. This study is intended to determine susceptibility and resistance pattern of pathogenic isolates from the rectal swabs of chicken to 8 antibiotics. Hundred (100) rectal swabs of chickens were collected randomly from three different farms; a farm at Montan, Awotan, Apete and Apata all in Ibadan Metropolis of Oyo State. Isolation and identification of organisms were done using standard bacteriological techniques. Antimicrobial susceptibility test was performed following standard protocol. A total of 93 bacterial isolates were obtained from the hundred (100) rectal swaps of chicken. The isolates Escherichia Coli, Staphylococcus aureus and Salmonella spp. and their percentage of prevalence are 54, 43 and 3. Antibiotic susceptibility tests carried out on the isolates showed that most of the isolates were resistant to ofloxacin, cloxacillin and Augumentin, while almost all the isolates in this study are sensitive to gentamicin. Erythromycin did not have any effect on any of the bacterial isolates. Bacterial isolates obtained in the study area were multi drug resistant and this suggests that the chickens are important reservoir of antimicrobial resistant organism which is a major public health concern

Graded q-pseudo-differential Operators and Supersymmetric Algebras

We give a supersymmetric generalization of the sine algebra and the quantum algebra $U_{t}(sl(2))$. Making use of the $q$-pseudo-differential operators graded with a fermionic algebra, we obtain a supersymmetric extension of sine algebra. With this scheme we also get a quantum superalgebra $U_{t}(sl(2/1)$.Comment: 10 pages, Late

The Vibrational Spectrum of the hydrated Alanine-Leucine Peptide in the Amide region from IR experiments and First Principles Calculation

We have combined infrared (IR) experiments with molecular dynamics (MD) simulations in solution at finite temperature to analyse the vibrational signature of the small floppy peptide Alanine-Leucine. IR spectra computed from first- principles MD simulations exhibit no distinct differences between conformational clusters of alpha-helix/beta-sheet-like folds with different orientations of the bulky leucine side chain. All computed spectra show two prominent bands, in good agreement with the experiment, that are assigned to the stretch vibrations of the carbonyl and carboxyl group, respectively. Variations in band widths and exact maxima are likely due to small fluctuations in the backbone torsion angles