Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

The thermal conductivity κ(T) of the fully ordered stable phase II, the metastable phase III, the orientationally disordered (plastic) phase I, as well as the nonergodic orientational glass (OG) phase, of the glass former cyclohexanol (C 6H 11OH) has been measured under equilibrium vapor pressure within the 2-200 K temperature range. The main emphasis is here focused on the influence of the conformational disorder upon the thermal properties of this material. Comparison of results with those regarding cyanoclyclohexane (C 6H 11CN), a chemically related compound, serves to quantify the role played by the terminal groups -OH and -CN on the phonon scattering processes. The picture that emerges shows that motions of such groups do play a minor role as scattering centers, both within the low-temperature orientationally ordered phases as well as in the OG states. The results are analyzed within the Debye-Peierls relaxation time model for isotropic solids comprising mechanisms for long-wave phonon scattering within the OG and orientational ordered low-temperature phases, as well as others arising from localized short-wavelength vibrational modes as pictured by the Cahill-Pohl model. By means of complementary neutron and Raman scattering we show that in the OG state the energy landscapes for both compounds are very similar. © 2012 American Physical Society.This work was financially supported in part by the Spanish Ministry of Science and Innovation (Grant No. FIS2008-00837) and the Catalan Government (Grant No. 2009SGR-1251)Peer Reviewe

Measurement of the Nucleon Structure Function F2 in the Nuclear Medium and Evaluation of its Moments

We report on the measurement of inclusive electron scattering off a carbon target performed with CLAS at Jefferson Laboratory. A combination of three different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an invariant mass of the final-state hadronic system W~2.4 GeV with four-momentum transfers Q2 ranging from 0.2 to 5 GeV2. These data, together with previous measurements of the inclusive electron scattering off proton and deuteron, which cover a similar continuous two-dimensional region of Q2 and Bjorken variable x, permit the study of nuclear modifications of the nucleon structure. By using these, as well as other world data, we evaluated the F2 structure function and its moments. Using an OPE-based twist expansion, we studied the Q2-evolution of the moments, obtaining a separation of the leading-twist and the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist contributions to the F2 moments exhibits the well known EMC effect, compatible with that discovered previously in x-space. The total higher-twist term in the carbon nucleus appears, although with large systematic uncertainites, to be smaller with respect to the deuteron case for n<7, suggesting partial parton deconfinement in nuclear matter. We speculate that the spatial extension of the nucleon is changed when it is immersed in the nuclear medium.Comment: 37 pages, 15 figure

Association of paraoxonase activity and atherosclerosis in patients with chronic hepatitis B

Background: The hepatitis B virus is a significant pathogen that causes cirrhosis, and hepatocellular cancer as a result of the damage it causes to liver cells. Its infection affects more than 400 million people globally. Although there is an effective vaccine and treatment methods, almost 1, 000, 000 people die every year. Objective: To investigate paraoxonase and arylesterase activities along with oxidative status parameters and serum lipid levels, and to find out if there is any increased susceptibility to atherogenesis. Methods: Thirty-four subjects with chronic hepatitis B and 39 healthy subjects as control were enrolled in the study. Age, body mass index and gender, Serum Triglycerides (TG), High-density Lipoprotein (HDL) and Low-Density lipoprotein (LDL) levels, serum paraoxonase-1 and arylesterase activities were determined. Oxidative and antioxidative statuses were evaluated by measuring serum-free sulfhydryl groups, lipid hydroperoxide levels, total antioxidant capacity, total oxidant status, and oxidative stress index. Results: Serum TG and LDL levels were higher while serum HDL levels were lower in patients with chronic hepatitis B than in controls but the differences did not reach statistical significance. Serum paraoxonase-1 and arylesterase activities, plasma free sulfhydryl groups, and total antioxidant capacity were significantly lower in patients than in controls (p=0.018, p=0.005, p<0.001, p=0.037 respectively), while lipid hydroperoxide, total oxidant status, and oxidative stress index were significantly higher (for all p<0.001). Conclusion: The diminution in the paraoxonase-1 and arylesterase activities could contribute to the accelerated development of atherosclerosis in patients with chronic hepatitis B

Analysis of large scale linear programming problems with embedded network structures Detection and solution algorithms

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN204522 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

The thermal conductivity κ(T ) of the fully ordered stable phase II, the metastable phase III, the orientationally disordered (plastic) phase I, as well as the nonergodic orientational glass (OG) phase, of the glass former cyclohexanol (C6H11OH) has been measured under equilibrium vapor pressure within the 2–200 K temperature range. The main emphasis is here focused on the influence of the conformational disorder upon the thermal properties of this material. Comparison of results with those regarding cyanoclyclohexane (C6H11CN), a chemically related compound, serves to quantify the role played by the terminal groups -OH and -CN on the phonon scattering processes. The picture that emerges shows that motions of such groups do play a minor role as scattering centers, both within the low-temperature orientationally ordered phases as well as in the OG states. The results are analyzed within the Debye-Peierls relaxation time model for isotropic solids comprising mechanisms for long-wave phonon scattering within the OG and orientational ordered low-temperature phases, as well as others arising from localized short-wavelength vibrational modes as pictured by the Cahill-Pohl model. By means of complementary neutron and Raman scattering we show that in the OG state the energy landscapes for both compounds are very similar