On energy conservation and P-stability

When applied to the classical dynamical equations, generally, conventional time-stepping methods cannot conserve the total energy exactly, but up to their algebraic order. To obtain an energy-conserving method, we add an energy calibrated parameter to some conventional ones. The periodic stability and phase-lag property of this type of energy-conserving methods are investigated in this note. Some numerical results are reported to illustrate our conclusions.     

Ferroelectric metal-organic framework with a high dielectric constant

Hydrothermal reaction of (l)-N-(4'-cyanobenzy)-(S)-proline with CdCl2 as a Lewis acid catalyst and NaN3 gives colorless block compound 1, in which 1 displays a complicated 3D framework. Ferroelectric and dielectric property measurements reveal that 1 exhibits physical properties comparable to that of a typical ferroelectric compound with a dipole relaxation process and a dielectric constant of ca. 38.6 that makes it, by definition, a high dielectric material.     

High-affinity binding and direct electron transfer to solid metals by the Shewanella oneidensis MR-1 outer membrane c-type cytochrome OmcA

The purified outer membrane bacterial protein OmcA binds densely to the surface of hematite (Fe2O3), permitting direct electron transfer to this solid mineral to reduce Fe (III) with an electron flux of about 1013 electrons /cm2/s. In the presence of hematite, there is a substantial increase in the amplitude of internal protein motions that correlate with metal reduction. Binding is highly favorable, with a partition coefficient of approximately 2 x 105 (DeltaGo' = -28 kJ/mol), where approximately 1014 OmcA proteins bind per cm2 to the solid metal surface, indicating the utility of using purified OmcA in the construction of a biofuel cell.     

Results of L-[1-13C]phenylalanine breath test with air isotope ratio mass spectrometry can reflect the activity of phenylalanine hydroxylase in cirrhotic rat liver

The L-[1-13C]phenylalanine breath test (PheBT) could potentially advance the evaluation of hepatocyte function and liver functional reserve. However, because the factors influencing PheBT results have not been clarified, the clinical application of the test has been limited. This study investigated the relationship between the parameters of PheBT, performed with air isotope ratio mass spectrometry, and the activity of phenylalanine hydroxylase (PAH), the phenylalanine metabolism rate-limiting enzyme, in rat liver, and proposes valid parameters for the assessment of liver function. Chronic injury to the liver was induced by the administration of CCl4 to male Sprague-Dawley rats for either 8 or 12 weeks. Livers from rats in the two cirrhotic groups were discolored, enlarged and roughly textured, with cells filled with fat granules of various sizes, pseudolobuli formations, and regenerated tubercles. Of the 12 parameters tested, only the unit liver weight (LW) breath test parameters, including the maximum abundance of 13C in breath (13Cmax/LW), 13C abundance in breaths 2 and 7 min after administration of L-[1-(13)C]phenylalanine (13C-phe) (13C2/LW and 13C7/LW), cumulative 13C excretion 10 and 30 min after 13C-phe administration (AUC10/LW and AUC30/LW), and the 13C excretion rate constant (PheBT-k/LW) were significantly affected in the chronic liver injury groups. There was no significant difference in the total PAH activity in liver among the three groups, but there was significant difference in unit LW PAH activity. Total PAH activity in the liver was significantly correlated with 13Cmax, 13C2, 13C7, AUC10, AUC30 and PheBT-k, while the unit LW PAH activity was significantly correlated with 13Cmax/LW, 13C2/LW, 13C7/LW, AUC10/LW, AUC30/LW and PheBT-k/LW. PheBT-k/LW was also correlated with biochemical indices that are used to assess liver function. The present findings indicate that the PheBT results based on air isotope ratio mass spectrometry can quantitatively reflect the change in total PAH activity in the livers of chronically injured rats. PheBT-k and PheBT-k/LW are the most sensitive among the test parameters, and can be used to assess liver functional reserve and hepatocyte damage at the molecular level.     

Continuous spin fractionation and characterization by size-exclusion chromatography for styrene-butadiene block copolymers

Linear and star-shaped styrene-butadiene block copolymers synthesized by anionic polymerization of butadiene and styrene were fractionated by applying a newly developed large-scale fractionation technique, named continuous spin fractionation (CSF). Their molecular weight and polydispersity index (d=M(w)/M(n)) were measured with size-exclusion chromatography and static light scattering. For the linear triblock copolymer a fractionation via temperature variation turned out to be better suited than the usual isothermal procedure. The star-shaped polymer with the d value of 1.33 was fractionated in two CSF steps to get the targeted sample, which has a considerably more uniform structure and a narrower molecular weight distribution (d=1.11). The corresponding starting linear diblock copolymer was fractionated in one step reducing d from 1.68 to 1.17. With one set of simple laboratory equipment, 1kg polymer can be fractionated per day. Utilizing CSF, for the first time, we fractionated successfully the block copolymers.     

Analysis of multiplex PCR fragments with PMMA microchip

Microchip electrophoresis is a promising technique for analysis of bio-molecules. It has the advantages of fast analysis, high sensitivity, high resolution and low-cost of samples. Plastic chip has the potential of mass production for clinical use for its advantages in biocompatibility and low cost. In this work, the method for fabrication of poly(methyl methacrylate) (PMMA) chip was described, and conditions for DNA separation were investigated with the chip. The PMMA microchip was used for detection of multiplex PCR products of 18 and 36 cases with SARS and hepatitis B virus infection under optimized separation conditions. Microchip electrophoresis showed higher sensitivity, higher resolution and less time consumption when compared with gel electrophoresis. The microchip electrophoresis with PMMA chip provided a rapid, sensitive and reliable method for analysis of multiplex PCR products.     

New barium cobaltite series Ba(n+1)Co(n)O(3n+3)(Co8O8): intergrowth structure containing perovskite and CdI2-type layers

Single crystals of two new cobaltites, Ba2Co9O14 and Ba3Co10O17, were obtained from the flux of K2CO3 in the temperature range 800-890 degrees C. They crystallize in an intergrowth structure containing perovskite block and CdI2-type layers and can be attributed to the n = 1 and 2 members in a new intergrowth series of cobaltites, Ba(n+1)Co(n)O(3n+3)(Co8O8). Both Ba2Co9O14 and Ba3Co10O17 are metastable and transform into the known 2H-perovskite-related oxides at high temperature.