Righi-Leduc effect in the mixed state of a type-II superconductor

A transverse temperature gradient odd in magnetic field has been observed in the presence of longitudinal temperature gradient in a thin strip of Pb + 7.5 at. % In with its plane perpendicular to the field. At 2.5°K, the ratio of the transverse to the longitudinal temperature gradient is proportional to field above the upper critical field, and has a maximum in the mixed state below this field. The Righi-Leduc effect has the same sign in the mixed state as in the normal state.Research supported by the National Science Foundation.National Science Foundation traince.     

Synthesis,characterization and thermal properties of a novel star polymer consisting of poly(ε-caprolactone) arms emanating from an octa-functional porphyrazine core

Octaarmed star-shaped poly(ε-caprolactone) (OSPCL) was successfully synthesized via the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with a magnesium porphyrazine as the multisite initiator and tin(II) 2-ethylhexanoate (Sn(Oct₂)) as the catalyst in bulk at 115 °C. The star polymer has a central Mg-porphyrazine surrounded by ε-CL arms. OSPCL was characterized by ¹H NMR, FTIR, GPC and UV–vis, and fluorescent spectroscopy. The effect of the molar ratio of the monomer to the initiator on molecular weight of the polymer was also investigated. The molecular weight of the polymer linearly increased with increasing molar ratio of the monomer to the initiator. The crystallization behavior of OSPCL was studied using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). OSPCL displayed an interrupted crystal morphology owing to its highly branched architecture, and consequently, the degree of crystallinity was lower in comparison with the linear analogue. Thermogravimetric analysis (TGA) clearly indicated that incorporation of porphyrazine core enhanced the thermal stability of the resulting polymers.     

Preparation of novel UV-curable methacrylated urethane resins from a modified epoxy resin and isocyanatoethylmethacrylate (IEM)

Summary New UV curable methacrylated urethanes (PAPHEN-XIEM) were synthesized by substituting X percent (e.g., 10, 20, 30 %) of the total OH content of the PAPHEN-301 (Scheme 1) with isocyanatoethyl methacrylate (IEM). These resins were used alone (neat resin formulation) or as a mixture of 5, 10 and 13 % (w/w) respectively with methacrylated urethane prepolymer (PTHFUMA) in UV systems. For neat resin formulations, tensile strength and modulus values were observed to be inversely proportional with the modification degree of PAPHEN-301 as opposed to what is normally expected. This may be explained as a result of screening effect of increasing unsaturation. The water absorption capacities for neat resins and PTHFUMA-included formulations were decreased as the modification degree increased due to the replacement of hydrophilic OH groups of PAPHEN-301 by the hydrophobic methacrylate groups. TGA thermograms of neat resin formulation show that, initial weight loss temperatures are lower; possibly owing to the higher methacrylate content in the formulations. Received: 26 June 2001/Revised version: 5 April 2001/Accepted: 5 April 2001     

Phenolics profiles of olive fruits (Olea europaea L.) and oils from Ayvalık,Domat and Gemlik varieties at different ripening stages

Phenolic compounds in olive fruit and oils obtained from Ayval?k, Domat and Gemlik olive varieties collected at different ripening periods were evaluated by High Performance Liquid Chromatography (HPLC). Gallic acid and p-cumaric acid were identified for Ayval?k and Domat at each period of ripening, respectively. In addition, gallic acid, p-cumaric acid, sinapinic and apigenin acids were detected in Gemlik olive fruit. Hydroxytyrosol, rutin, oleoropein, luteolin, tyrosol, vanilic acid and gallic acid in Ayval?k olive fruit in all ripening periods were determined. The tyrasol contents varied between 0.18 to 1.57 mg/kg. Luteolin contents of olive oils ranged at the levels between 0.12 to 2.28 mg/kg. In contrast, oils had the lowest syringic, p-cumaric, chlorogenic and ferulic acids. Vanillic acid contents of oils ranged between 0.08 to 2.38 mg/kg.     

Antioxidant,Antimicrobial, Antifungal,and Antiradical Activities of Cyclotrichium Niveum (BOISS.) Manden and Scheng

In Turkish kitchen, Cyclotrichium niveum, which is consumed as a dietary supplement, have been extensively used in soup and food for their odor and flavor. The present study examines the possible antioxidant, antimicrobial and radical scavenging capacity of Cyclotrichium niveum (Boiss.) Manden and Scheng. In order to evaluate antioxidant and radical scavenging activity different in vitro methodologies such as 2,2´-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, 1,1-diphenyl-2-picryl-hydrazyl (DPPH·) free radical scavenging, total antioxidant activity by ferric thiocyanate, total reducing power by potassium ferricyanide reduction method, superoxide anion radical scavenging, hydrogen peroxide scavenging, and ferrous ions chelating activities were used. In addition, antimicrobial and antifungal activity of the both extracts tested against twenty five microorganisms. Total phenolic compounds and total flavonoids contents in water extract of Cyclotrichium niveum (Boiss.) Manden. & Scheng (WECN) and ethanol extract of Cyclotrichium niveum (Boiss.) Manden. & Scheng (EECN) were determined.     

Power Characteristics and Temperature Dependence of the Angular Beam Divergence of Lasers with a Near-Surface Active Region

Results are presented of a study of light–current characteristics and far-field patterns of emission of stripe lasers with coupled planar waveguides. This configuration makes it possible to suppress the generation of excited modes and to have a small (about 0.9 μm) depth of the active region from the surface of the laser crystal. A high-temperature stability of the angular emission divergence (34.0° ± 1.5°) in the temperature range 20–80°C is demonstrated. The largest value of the output power is limited to 12.2 W in the continuous-wave mode by the catastrophic mirror damage.