Poly-3-Hydroxyalkanoates containing unsaturated repeating units produced by pseudomonas oleovorans

Poly-3-hydroxyalkanoates (PHAs) containing repeating units with terminal alkene substituents at the 3-position were produced by Pseudomonas oleovorans grown with either 7-octeneoic acid [OA(?)] alone, or 10-undeceneoic acid [UND(?)] alone, or mixtures of UND(?) and either nonanoic acid (NA) or octanoic acid (OA). For the latter, the biomass and PHA yields decreased as the fraction of UND(?) increased in the mixed carbon substrates. Essentially all of the repeating units in the PHA obtained from cells grown with UND(?) alone contained terminal alkene groups, including 3-hydroxy-10-undeceneoate, 3-hydroxy-8-noneneoate, and 3-hydroxy-6-hepteneoate units, but less than half of the units in the PHA from OA(?) had alkene substituents. The PHAs obtained from cells grown with various mixtures of UND(?) and either OA or NA were random copolymers, and the fraction of units with alkene substituents in these polymers increased in proportion to the fraction of UND(?) in the mixed carbon substrates. © 1995 John Wiley & Sons, Inc.     

On redundance in aperiodicity criteria

A previous partial proof of necessary and sufficient conditions for a system to be aperiodic (i.e. to have its characteristic roots all real and simple) is completed in the present paper. Explicit account is taken of the irregular case when the number of Sturm functions is less than the usual number. The number of inequalities in the aperiodicity criteria is n ? 1 where n is the degree of the characteristic equation; and for n = 3 it is known that one of the inequalities is redundant. The present investigation shows that redundance does not occur for n ≠ 3. A similar study is made of redundance in criteria for combined aperiodicity and stability.     

The input mobility of an infinite circular cylindrical elastic shell filled with fluid

The force input mobility of an infinite elastic circular cylindrical shell filled with fluid is derived by using the spectral equations of motion. Mobilities are evaluated and their physical interpretations are discussed for a steel shell of thickness $\text{h}\text{a}\text{= 0·05}$ filled with water and vibrating in the n = 0, 1 and 2 circumferential modes. The results are subsequently used to analyze the related situations of wave transmission through a radial ring constraint and the far field vibrational energy distributions between the contained fluid and the shell wall for line and point driving forces.     

Electronic structure of solid state tris(1,3-diphenyl-1,3-propanedionato)aquoeuropium(III)

Single crystal orthoaxial absorption spectra are reported for tris(1,3-diphenyl-1,2-propanedionato)aquoeuropium(III) at ambient temperature and 77 K. The hypersensitive ⁷F_o→⁵D₂ and magnetic/electric dipole forbidden ⁷F_o→⁵D_o transitions are found to be unusually intense. Polarizations and absolute oscillator strengths are determined for all observed transitions from the ground state at 77 K.     

IR-Untersuchungen über die Wassersorption an polymorphen ZrO2-Produkten

Ohne Zusammenfassung     

Nuclear magnetic resonance pulse sequence and discrimination of high- and low-fat tissues

Signal size compared to independently measured T1 is described for various pulse sequences on the Aberdeen Mk II nuclear magnetic resonance imager. The ability of these sequences to discriminate between certain tissue types, and in particular between adipose tissue and muscle, is discussed. Inversion recovery, with a t interval of 200 ms, gives the best discrimination for this purpose, with a contrast ratio of 6 between fat and muscle. Other image types, and especially T1, give better contrast for low-lipid soft tissue such as liver and spleen.     

Flow birefringence of concentrated polymer solutions in two-dimensional flows

The results of flow birefringence measurements are reported for polymer solutions of moderate concentration subjected to a wide range of two-dimensional flows. These flows were generated in a four-roll mill which enables one to systematically vary the ratio of the vorticity to the rate of strain in the flow while holding the velocity gradient constant. It is shown that steady-state birefringence data collected over a wide range of flow types can be correlated against the eigenvalue of the velocity gradient tensor, in agreement with criterion for strong and weak flows from model calculations. Transient birefringence measurements in which purely extensional flows were started from rest are also reported. It was observed that the birefringence went through a pronounced overshoot in time for two different polymer/solvent systems. Flow induced increases in the solution turbidity were also observed and the increased turbidity remained constant over a period of many hours after extensional flows were arrested. The birefringence, on the other hand, decayed to zero almost immediately after the flows were stopped. These changes in the turbidity suggest that crystallization of the polymer was occurring. The qualitative results of experiments are compared to recent network model calculations using the theory of Yamamoto for concentrated polymer systems. It is found that this model can predict qualitatively many of the experimental observations if the function describing the breakage of polymer chain entanglements is allowed to depend on the conformation of the polymer segments bridging the entanglements. In particular, this dependency of the entanglement breakage on the conformation of the network segments leads to a predicted overshoot of birefringence when purely extensional flows are started from rest. It is also demonstrated through this model that birefringence data taken over a wide range of flow types can be used to estimate the degree to which the network deforms affinely with the flow field.     

EXHAUSTIBLE RESOURCES,LEARNING, AND THE THEORY OF THE SECOND BEST

We formulate and characterize the solutions to optimal control models of social welfare maximization in a resource industry composed of two parts — conventional, with unit cost that increases with cumulative production, and backstop, whose unit cost decreases with cumulative production, due to learning. Since marginal cost pricing leads to losses in backstop operations, we consider three “second best” constraints that ensure non-negative profits. These constraints introduce distortions away from marginal cost pricing. Two constraints cause a discontinuous upward jump in price at the time of transition from conventional to backstop, and a supply side distortion-violation of cost minimization to meet demand.     

Terminal phosphate-labeled nucleotides with improved substrate properties for homogeneous nucleic acid assays

Nucleotides with a dye attached to the terminal phosphate with four or more phosphates (tetra- or pentaphosphates) are superior substrates than the corresponding triphosphates for DNA and RNA polymerases. When fluorogenic dyes are directly attached to the terminal phosphate, they can be released by the action of polymerase and alkaline phosphatase. The released dye changes color and fluorescence properties. The fluorescent signal can also be amplified by using multiple labeled nucleotides to detect small amounts of template. We have explored the utility of these nucleotides in a variety of applications including homogeneous SNP detection methods, DNA sequencing, and quantitation of PCR and RCA.