Kinetic Ising model in a time-dependent oscillating external magnetic field: effective-field theory

Recently,Shi et al.[2008 Phys.Lett.A 372 5922] have studied the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field and presented the dynamic phase diagrams by using an effective-field theory(EFT) and a mean-field theory(MFT).The MFT results are in conflict with those of the earlier work of Tom’e and de Oliveira,[1990 Phys.Rev.A 41 4251].We calculate the dynamic phase diagrams and find that our results are similar to those of the earlier work of Tom’e and de Oliveira;hence the dynamic phase diagrams calculated by Shi et al.are incomplete within both theories,except the low values of frequencies for the MFT calculation.We also investigate the influence of external field frequency(ω) and static external field amplitude(h0) for both MFT and EFT calculations.We find that the behaviour of the system strongly depends on the values of ω and h0.     

Critical behavior of a mixed ferrimagnetic ternary alloy on the Bethe lattice

The critical behavior of the mixed Ising model of the type AB _p C_1−p ternary alloy consisting of spins σ = 1/2, S = 1, and m = 3/2 is investigated on the Bethe lattice by using the exact recursion relations. The exact expressions for the magnetizations and magnetic susceptibilities are found, and the thermal behaviors of the magnetizations and susceptibilities are studied. The magnetizations and susceptibilities have also been investigated as functions of the crystal-field interaction or single-ion anisotropy. The phase diagram has been constructed according to which the system always undergoes a second-order phase transition for the coordination number q ≤ 3 and second-and first-order phase transitions for q > 3; hence, the system has a tricritical point. The system also exhibits reentrant behaviors. The text was submitted by the authors in English.     

1H magnetic resonance spectroscopy of the normal testis: preliminary findings

PURPOSE: The purpose of this study was to determine the pre- and postpubertal 1H magnetic resonance spectroscopic characteristics of the normal testis to establish baseline values for further clinical studies. MATERIALS AND METHODS: The subjects consisted of male volunteers, of whom 19 were prepubertal with ages between 7 and 13 years and 24 were postpubertal with ages between 19 and 39 years. Their testes were evaluated at 1.5 T with magnetic resonance spectroscopy; in addition, testis volumes were measured. Major metabolite peaks were identified and their ratios were calculated. Metabolite differences of testis between pre- and postpubertal age were analyzed. RESULTS: Major constituents of spectra were 3.21 ppm choline and 0.9-1.3 ppm lipid peaks. At the echo time (TE) spectrum of 31 ms, choline/lipid ratios ranged from 0.35 to 8.30 (mean=1.87) in postpubertal males and from 0.06 to 5.45 (mean=0.88) in prepubertal males (P<.013). At the TE spectrum of 136 ms, choline/lipid ratios ranged from 0.66 to 15.42 (mean=4.09) in postpubertal males and from 0.05 to 4.91 (mean=0.9) in prepubertal males (P<.016). CONCLUSIONS: Choline/lipid ratio was higher in the postpubertal period. The existence of higher choline peak in that age group should be due to the initiation of spermatogenesis. The decrease in the lipid peak may represent the effect of testosterone on testicular tissue or may be due to histochemical changes initiated by puberty. The significant decrease in choline/lipid ratio noted after puberty could represent the presence of spermatogenesis. This hypothesis should be evaluated by further studies on postpubertal subjects with impaired spermatogenesis.     

Conformal Riemannian Maps between Riemannian Manifolds,Their Harmonicity and Decomposition Theorems

Riemannian maps were introduced by Fischer (Contemp. Math. 132:331–366, 1992) as a generalization isometric immersions and Riemannian submersions. He showed that such maps could be used to solve the generalized eikonal equation and to build a quantum model. On the other hand, horizontally conformal maps were defined by Fuglede (Ann. Inst. Fourier (Grenoble) 28:107–144, 1978) and Ishihara (J. Math. Kyoto Univ. 19:215–229, 1979) and these maps are useful for characterization of harmonic morphisms. Horizontally conformal maps (conformal maps) have their applications in medical imaging (brain imaging)and computer graphics. In this paper, as a generalization of Riemannian maps and horizontally conformal submersions, we introduce conformal Riemannian maps, present examples and characterizations. We show that an application of conformal Riemannian maps can be made in weakening the horizontal conformal version of Hermann’s theorem obtained by Okrut (Math. Notes 66(1):94–104, 1999). We also give a geometric characterization of harmonic conformal Riemannian maps and obtain decomposition theorems by using the existence of conformal Riemannian maps.     

Magnetic properties of the mixed ferrimagnetic ternary system with a single-ion anisotropy on the Bethe lattice

The magnetic properties of the ternary system ABC consisting of spins , S=1, and are investigated on the Bethe lattice by using the exact recursion relations. We consider both ferromagnetic and antiferromagnetic exchange interactions. The exact expressions for magnetizations and magnetic susceptibilities are found, and thermal behaviors of magnetizations and susceptibilities are studied. We construct the phase diagrams and find that the system exhibits one, two or even three compensation temperatures depending on the values of the interaction parameters in the Hamiltonian. Moreover, the system undergoes a second-order phase transition for the coordination number q?3 and a second- and first-order phase transitions for q>3; hence the system gives a tricritical point. The system also exhibits the reentrant behaviors.     

Synthesis and Antimicrobial and Antioxidant Activities of Sulfonamide Derivatives Containing Tetrazole and Oxadiazole Rings

In the present work, we synthesized new sulfonamide derivatives with 1,3,4‐oxadiazole moiety and tetrazole ring. The synthesized derivatives of sulfonamides were characterized through Fourier transform infrared, ¹³C‐APT‐NMR, ¹H‐NMR, and high‐resolution liquid chromatography–mass spectrometry. The biological activities of resulting compound were also investigated and observed that the compounds reveal strong antimicrobial activity over some important bacterial strains including Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 13883, and Staphylococcus aureus ATCC 29213. The in vitro antifungal properties of synthesized compounds were also a target using Candida albicans NRRL Y‐477 and Saccharomyces cerevisiae fungal strains. We have provided a useful guideline for future studies about the effect of the chemical structures of sulfonamide compounds on the biological activities. Among the target compounds, 7b , 7c , 7d , and 7e demonstrated surprisingly high antimicrobial activities than did others.     

InGaN green light emitting diodes with deposited nanoparticles

We grew an InGaN/GaN-based light-emitting diode (LED) wafer by metal–organic chemical vapor deposition (MOCVD), fabricated devices by optical lithography, and successfully deposited ellipsoidal Ag nano-particles by way of e-beam lithography on top. The diodes exhibited good device performance, in which we expected an enhancement of the radiated intensity by the simulations and emission measurements. The obtained results showed the feasibility of plasmon-assisted LED emission enhancement.     

Cytotoxicity of Silica Nanoparticles with Transcaucasian Nose-Horned Viper, <Emphasis Type="Italic">Vipera ammodytes transcaucasiana</Emphasis>, Venom on U87MG and SHSY5Y Neuronal Cancer Cells

Highly bioactive compounds of the snake venom make them particular sources for anticancer agent development. They contain very rich peptide-protein structures. Therefore, they are very susceptible to environmental conditions such as temperature, pH, and light. In this study, Vipera ammodytes transcaucasiana venom was encapsulated in PAMAM-G4 dendrimer by sol-gel method in order to prevent degradation of venom contents from the environmental conditions. For this purpose, nanoparticles were prepared by sol-gel methodology and SEM analyses were performed. U87MG and SHSY5Y neuronal cancer cell lines were treated with different concentrations of venom-containing nanoparticles and cytotoxicity was determined by MTT assay. IC₅₀ values of nanoparticles with snake venom were calculated as 37.24 and 44.64 μg/ml for U87MG and SHSY5Y cells, respectively. The IC₅₀ values of nanoparticles with snake venom were calculated as 10.07 and 7.9 μg/ml for U87MG and SHSY5Y cells, respectively. As a result, nanoparticles with V. a. transcaucasiana venom showed remarkably high cytotoxicity. Encapsulation efficiency of nanoparticles with 1 mg/ml snake venom was determined as %67 via BCA? protein analysis. In conclusion, this method is found to be convenient and useful for encapsulating snake venom as well as being suitable for drug delivery systems.     

Some thermal characteristics of a mineral mixture of palygorskite,metahalloysite, magnesite and dolomite

An industrial raw material taken from Sivrihisar (Eskişehir, Turkey) region was heat-treated at different temperatures in the range of 100–1000°C for 2 h. The volumetric percentage of the particles having a diameter below 2 μm after staying in an aqueous suspension of the material was determined as 67% by the particle size distribution analysis. The mineralogical composition of the material was obtained as mass% of 32% palygorskite, 10% metahalloysite, 35% magnesite, 20% dolomite and 3% interparticle water by using the acid treatment, X-ray diffraction and thermal analysis (TG, DTA) data. The temperature ranges were determined for the endothermic dehydrations for the interparticle water as 25–140°C, for the zeolitic water as 140–320°C, and for the bound water as 320–480°C, in the palygorskite. The temperature range for the endothermic dehydroxylation and exothermic recrystalization of the palygorskite is 780–840°C. The temperature range for the endothermic dehydroxylation of the metahalloysite and calcinations of magnesite are coincided at 480–600°C. Dolomite calcined in the temperature range of 600–1000°C by two steps. The zig-zag changes in the specific surface area (S/m² g⁻¹) and specific micro and mesopore volume (V/cm³ g⁻¹) as the temperature increases were discussed according to the dehydrations in the palygorkskite, dehydroxylation of palygorskite and metahalloysite, and calcinations in magnesite and dolomite.     

Adsorption of benzoic acid onto high specific area activated carbon cloth

The adsorption of benzoic acid from aqueous solution onto high area carbon cloth at different pH values has been studied. Over a period of 125 min the adsorption process was found to follow a first-order kinetics and the rate constants were determined for the adsorption of benzoic acid at pH 2.0, 3.7, 5.3, 9.1, and 11.0. The extents of adsorption and the percentage coverage of carbon cloth surfaces were calculated at 125 min of adsorption. Adsorption isotherms at pH values of 2.0, 3.7, and 11.0 were derived at 25 degrees C. Isotherm data were treated according to Langmuir and Freundlich equations and the parameters of these equations were evaluated by regression analysis. The fit of experimental isotherm data to both equations was good. It was found that both the adsorption rate and the extent of adsorption at 125 min were the highest at pH 3.7 and decreased at higher or lower pH values. The types of interactions governing in the adsorption processes are discussed considering the surface charge and the dissociation of benzoic acid at different pH values.