No abstract

Cesium hydrogen sulphate CsHS04 and cesium hydrogen selenate CsHSe04 are pseudo-one-dimensional hydrogen bonded systems /1, 2/ with a structure resembling that of CsH2P04 in the paraelectric phase apart from the extra hydrogen in CsH2P04 /l/. At room temperature CsHS04 belongs t o the monoclinic space group P21/m with a = 7.304 8 , b = 5.810 8 , c = 5. 491 %, @ = = 101 .51° and two formula units per unit cell /1/ (Fig. 1). Separate chains of 0 -H --0 bonded SO4 groups run along the b-axis /l/. The length of the 0-H--0

The NMR relaxation times T'2, T2, and T1 were measured in isolated rat lungs as functions of external magnetic field B0, temperature, and lung inflation. The observed linear dependence on B0 of the tissue-induced free induction decay rate (T'2)-1 provides independent confirmation of the air/water interface model of the lung. Furthermore, measurements of the Larmor frequency dependence of T1 are consistent with a spin-lattice relaxation rate of the form 1/T1 = A omega -1/2 + B as expected for the case in which the relaxation arises from water-biopolymer cross-relaxation, which should be proportional to the surface area of the lung. This prediction was verified by observations of an approximately linear dependence of 1/T1 on transpulmonary pressure and thus on the lung surface area.

The time evolution of the magnetization relaxation recovery of exchangeable water in ordinary Portland cement and white cement have been studied as functions of the hydration time together with the temperature and Larmor frequency dependence of the proton spin-lattice relaxation rates. The water self-diffusion coefficient was also studied as a function of both the hydration time and the diffusion time. The results show that the exchangeable water relaxes via cross relaxation to the gel protons, which are in turn relaxed via spin diffusion to paramagnetic impurities. The roughness of the gel-water interface and the wide distribution of pore sizes result in a stretched exponential nuclear magnetization relaxation recovery with the exponent reflecting the fractal geometry of the hydrating cement gel.

No abstract

The dependence of the water self-diffusion coefficients as well as of the proton spin-lattice and spin-spin relaxation rates on the concentration have been studied in the gelatin-water system and in hydrated native collagen. The bound and free water fractions and the corresponding spinspin and spin-lattice relaxation rates have been determined within the multi-phase water proton exchange model. Various theoretical models for the water proton cross-relaxation to the biopolymer have been studied and the results compared with the observed Larmor frequency dependence of the water proton spin-lattice relaxation rate.

The recently finalized Versatile Video Coding (VVC) standard promises to reduce the video bitrate by 50% compared to its predecessor, High Efficiency Video Coding (HEVC). The increased efficiency comes at a cost of increased computational burden. The Fraunhofer Versatile Video Encoder VVenC is the first openly available optimized implementation providing access to VVC's efficiency at only 46% of the runtime of the VVC test model VTM, when not using multi-threading. An alternative operating point allows 30× faster encoding for the price of around 12% bitrate increase, while still providing around 38% bitrate reduction compared to HEVC test model HM. In the fastest configuration, VVenC runs over 140× faster than VTM while still providing over 10% bitrate reduction compared to HM. Even faster encoding is possible with multi-threading. This paper provides an overview of VVenC's main features and some evaluation results.

The low temperature oxidation of Athabasca oil sand asphaltene observed from 13C, 19F and pulsed field gradient spin-echo proton n.m.r. spectra Desando, Michael A.; Lahajnar, Gojmir; Ripmeester, John A.; Zupancic, Ivan AbstractCarbon-13 and fluorine-19 nuclear magnetic resonance spectra of chemically derivatized, by phase transfer methylation and trifluoroacetylation, Athabasca oil sand asphaltene, reveal a broad site distribution of different types of hydroxyl-containing functional groups, viz., carboxylic acids, phenols, and alcohols. The low temperature air oxidation of asphaltene, at ca. 130ЊC for 3 days, generates a few additional carboxyl and phenolic groups. These results are consistent with a mechanism in which diaryl methylene and ether moieties react with oxygen. Self-diffusion coefficients, from the pulsed field gradient spin-echo proton magnetic resonance technique, suggest that low temperature oxidation does not appreciably alter the average particle size and diffusion properties of asphaltene in deuterochloroform. ᭧