Optical rotatory dispersion and circular dichroism studies of copolyaspartates with long alkyl side chain

Copoly(hexyl-l-aspartate-benzyl-l-aspartate), copoly(nonyl-l-aspartate-benzyl-l-aspartate) and copoly(dodecyl-l-aspartate-benzyl-l-aspartate) with various compositions were prepared by ester exchange reaction of poly(β-benzyl-l-aspartate). Copolyaspartates of low degree of alkylation were found to take a left handed α helix, similar to poly(β-benzyl-l-aspartate), and those of high degree of alkylation changed to a right handed α helix. Copoly(hexyl-l-aspartate-benzyl-l-aspartate) and copoly(dodecyl-l-aspartate-benzyl-l-aspartate) changed helix sense from left to right at 50% hexylation and 10% dodecylation, respectively. A small induced circular dichroism trough appeared around 230nm for these two copolyaspartates above 75% alkylation, indicative of a certain ordering of the carbonyl group due to the formation of an ordered structure of a long alkyl side chain. However, copoly(nonyl-l-aspartate-benzyl-l-aspartate) of 13% nonylation exhibited the induced circular dichroism spectrum and took a left handed α helix. Copoly(nonyl-l-aspartate-benzyl-l-aspartate) caused the reversal in helix sense above 70% nonylation according to a stabilizing effect of the ordered structure of the side chain.     

KINETICS OF β-GLUCAN DEGRADATION IN WORT BY EXOGENOUS β-GLUCANASES TREATMENT

Three commercial β-glucanases, one bacterial (Cereflo 200L from Novo) and two fungal (Biobeta from Gist-Brocades and Filtrase from Biocon) have been studied with regard to the hydrolysis of β-glucan in sweet and hopped wort. At temperatures below 70°C these processes follow first order kinetics with rate constants being directly proportional to the enzyme concentrations. The rate constant for bacterial β-glucanase Cereflo 200L shows a negative dependence on temperature but positive with wort pH, whereas the reverse is the case for the two fungal β-glucanases. Within the ranges of pH and temperature tested the bacterial β-glucanase has 2–5 times the activity of the fungal ones. No evidence for synergic or competitive effects between bacterial and fungal β-glucanases have been found.     

Clinical experience with continuous warm blood cardioplegia

We applied the Continuous Warm Blood Cardioplegia (CWBC) as an approach to improve myocardial preservation. From March to June in 1992, we used the CWBC in six patients and the conventional cold crystalloid cardioplegia (CCCP) in seven patients. All of them underwent isolated coronary artery bypass grafting. There was no marked difference between the CWBC and CCCP in post operative serum level of creatine kinase (MB type), cardiac output and dose of dopamine during they weaned from cardiopulmonary bypass. All patients treated with CWBC spontaneously restored the normal sinus rhythm shortly after removal of the aortic crossclamp, which was distinct from the fact that the CCCP group showed no such recovery. This result suggest that CWBC kept high-energy phosphate level without disturbing production of ATP in myocardium. Furthermore, reperfusion injury was also likely to be prevented by CWBC.     

Rheo-optical studies on the deformation mechanism of semicrystalline polymers: 2. Analyses of orientational and form birefringence of tubular-extruded poly(butene-1) films

Birefringence studies have been carried out to assess amorphous chain orientation of the ‘row-nucleated’ superstructure developed by crystallization from oriented melts. Birefringence, measured as a function of percentage elongation of film specimens subjected to stretching along the extrusion direction (the films are prepared by a tubular extrusion) and as a function of the refractive indices of the immersion liquid was separated into orientational and form birefringences. The orientational birefringence was further separated into the birefringence arising from crystal orientation and that from the amorphous chain orientation, utilizing orientation measurements made on crystals by wide-angle X-ray diffraction; the results indicate that the two contributions are comparable for a particular value of the intrinsic birefringence of the crystal Δ°_c = 0.0108, and the contribution of the amorphous tie chains is substantial. The form birefringence contributes negatively to the total birefringence and the negative contribution increases with increasing percentage elongation owing to the special morphology of the stacked lamellae and the decrease of interlamellar density with stretching. Its contribution to the total birefringence is initially minor (～6%) but increases with elongation until most of the total birefringence arises from the form birefringence. The form birefringence calculated using Franklin's theory shows a relatively good agreement with the experimental values, indicating that the deformation model involving a uniform interlamellar lowering of density is appropriate.     

Effect of carbon deposition by carbon monoxide disproportionation on electrochemical characteristics at low temperature operation for solid oxide fuel cells

The deterioration by carbon deposition was evaluated for electrolyte- and anode-supported solid oxide fuel cells (SOFCs) in comparison with carbon monoxide disproportionation and methane cracking. The polarization resistance of the nickel-yttria stabilized zirconia (Ni-YSZ) anode increased with a rise in CO concentration in H₂-CO-CO₂ mixture for the electrolyte-supported cells at 923 K. The resistance, however, did not change against CO concentration for the anode-supported cells. In a methane fuel with a steam/carbon (S/C) ratio of 0.1, the cell performance decreased for both of the cells at 1073 K. A large amount of agglomerated amorphous carbon was deposited from the anode surface to the interface between the anode and the electrolyte after power generation at S/C = 0.1 in methane fuel. On the other hand, the crystalline graphite was deposited only at the anode surface for the anode-supported cell after power generation in CO-CO₂ mixture. These results suggest that the reaction rate of CO disproportionation is faster than that of methane cracking. The deposited carbon near the anode/electrolyte interface caused the increase in the polarization resistance.     

Estimating reflectance and shape of objects from a single cartoon-shaded image

Computational Visual Media - Although many photorealistic relighting methods provide a way to change the illumination of objects in a digital photograph, it is currently difficult to relight...     

Rheo-optical studies on the deformation mechanism of semicrystalline polymers. 1. Deformation mechanism and recoverability of deformation of tubular extruded polybutene-1 films

Rheo-optical studies (involving small-angle X-ray and light scattering, wide-angle X-ray diffraction, and birefringence studies) have been applied to polybutene-1 films prepared by tubular extrusion (the preparation involving crystallization from oriented melts) to investigate the fundamental orientation and deformation mechanisms of molecules (in the crystalline and amorphous regions) and crystalline supermolecular structure. It is shown that the molecular orientation behaviour can be described by deformation of the ‘row-nucleated’ sheaf-like crystalline superstructure and that the deformation of the interlamellar spacing is quite uniform, the microscopic strain being identical to the strain in bulk specimens. The latter is quite important in understanding apparent ‘springy’ or ‘hard-elastic’ properties of the films observed at temperatures above the glass transition of the films. In relation to the springy properties, recoverabilities of the molecular and supermolecular structures from large extensions have been also studied.     

Contrast-to-gradient method for the evaluation of image resolution taking account of random noise in scanning electron microscopy

We have taken random image noise into consideration in the contrast-to-gradient (CG) method for the evaluation of image resolution R in scanning electron microscopy (SEM). When looking at the local fine pattern in the SEM micrograph containing much random noise, viewers gradually expand the region of interest (ROI) to improve the signal-to-noise ratio (SNR) and to recognize the pattern. We employed this approach in the CG algorithm to evaluate potential resolution Rpot, which is defined as the minimal/most accurate CG resolution calculated in the ROI expanding process. The image noise or SNR also is evaluated by the parameter deltaR / R, where deltaR is a standard deviation of R. The Rpot values depending on SNR are useful for comparison among images containing different random noise.