Synthesis of a secretoglobin 3A2 type C (98–139) fragment by Dawson’s native chemical ligation

A secretoglobin 3A2 type C (98–139) peptide was synthesized by native chemical ligation between ¹¹⁵Ile and ¹¹⁶Cys residues using Dawson’s linker. The peptide-N-acyl-benzimidazolinone-glycine amide, a C-terminal thioesters precursor, was provided from 3-amino-4-(methylamino)benzoic acid. In addition, an N-terminal cysteine fragment, the (116–139) peptide, was prepared by ordinary Fmoc-solid phase peptide synthesis. Native chemical ligation of the (98–115) fragment with the Dawson’s linker and the (116–139) peptide smoothly proceeded to give SCGB3A2 type C (98–139) peptide.     

Turbulence structure of air-water bubbly flow—III. transport properties

An experimental study of heat and bubble transport in turbulent air-water bubbly flow was carried out by means of tracer techniques. Helium tracer gas concentration data and temperature distributions were used to extract bubble and heat diffusivity information. The results indicated that the turbulent velocity components of the liquid phase play a predominant role in the turbulent transport process. A systematic increase of diffusivity of heat, ?_H, with quality and water velocity was observed. An empirical correlation for the diffusivity ratio ?_H,TP/?_H,SP is presented. The Péclet number, u′_covbar|dφ, for bubble dispersion can be approximated by 2.0, independent of the flow variables. The bubble-to-heat diffusivity ratio, φ/?_H, approaches unity with increasing quality and water velocity. Momentum transport is also discussed, based on a mixing length theory.     

Preparation and properties of A-B-A tri-block copolymer membranes consisting of N-hydroxypropyl-l-glutamine as the A component and l-alanine as the B component

A-B-A type tri-block copolymer consisting of N-hydroxypropyl-l-glutamine as the A component and l-alanine as the B component as well as the corresponding random copolymers and homopolymers were prepared by carrying out an aminoalcoholysis reaction with 3-amino-1-propanol, together with a crosslinking reaction with 1,8-octamethylenediamine on membranes of the starting polymer membranes including γ-methyl-l-glutamate residue. It was shown that the effective crosslink density was proportional to the percent crosslinker in the reaction mixture. The relation between their bulk structure and membrane properties were investigated, such as the swelling ratio in water (q), tensile properties, and enzymatic degradation behavior of the membranes in a pseudo-extracellular fluid (PECF). The tensile properties of the hydrophilic membranes were highly dependent on q in PECF, and on the hydrophobic portions in molecular chains, whose behavior was typical of an elastomer. Biodegradation of the membranes in vitro by bromelain indicated that the degradation took place in bulk rather than on the surface, and that the rate of degradation was also highly dependent on q in the samples as well as on the hydrophobic portion of the membranes in PECF.     

Immobilization of bromelain onto porous copoly(γ-methyl-l-glutamate/l-leucine) beads

Water-insoluble bromelain was prepared by immobilizing bromelain onto the surface of porous copoly(γ-methyl-l-glutamate/l-leucine) (ML) beads with and without spacer. The mode of the immobilization between bromelain and porous copolypeptide ML beads was covalent fixation. The relative activity and the stability of the immobilized bromelain was investigated. The retained activity of the bromelain covalently immobilized by the azide method was found to be excellent toward a small ester substrate, N-benzyl-l-arginine ethyl ester, but rather low toward casein, a high molecular weight substrate. The values of the Michaelis constant K_m and the maximum reaction velocity V_m for free and immobilized bromelain on the porous copolypeptide ML beads were estimated. Apparent K_m was larger for immobilized bromelain than for the free one, while V_m was smaller for the immobilized bromelain. The thermal stability of the covalently immobilized bromelain was higher than that of the free bromelain. The initial enzymatic activity of the immobilized bromelain remained approximately unchanged with storage time, when the batch enzyme reaction was performed repeatedly, indicating the excellent durability.     

Turbulence structure of air-water bubbly flow—II. local properties

Microstructure was studied experimentally in air-water two-phase bubbly flow flowing upward in a vertical pipe of 60 mm diameter under atmospheric pressure. The results indicate that over a large portion of fully-developed bubbly flow the phases, the velocities of bubbles and water, and the ratio between the velocities of the phases have fairly flat radial profiles. In the wall region a maximum void fraction was observed. Spectra of the velocities of bubbles and water showed a Poisson distribution and a normal distribution function, respectively. The experimental evidence indicated a trend for the turbulent intensity to decrease first with increasing gas flow rate for constant water velocity and to increase again with a further increase in the gas flow rate. This phenomenon was more significant for a higher water velocity.     

Local properties of vertical mercury-argon two-phase flow in a circular tube under transverse magnetic field

Experimental data are presented in this paper on the profiles of local void fraction, bubble impaction rate, bubble velocity and its spectrum, and also bubble length and its spectrum, of mercury-argon two-phase slug flow flowing upwards in a vertical circular tube in the presence of a transverse magnetic field. Decrease in void fraction and increase in bubble velocity are significant when the magnetic flux density is larger than $\text{0.3～0.4}$$\text{T}\text{(Ha ? 100)}$. This effect is discussed by analyzing the bubble size distribution. Recovery of local void fraction profile in the downstream of an obstacle and diffusion of void injected from only one nozzle in the presence of magnetic field are also discussed.     

Turbulence structure of air-water bubbly flow—I. measuring techniques

This paper, the first in a series describing our work on the turbulence structure of air-water bubbly flow, describes the principles of measurement and specially developed electronic instrumentation for determining various important local parameters, and the rates of turbulent transport of heat and bubbles in air-water two-phase bubbly flow. These instruments indicate the phase distribution, the bubble velocity and its spectrum, the water velocity and the turbulent intensity, and the turbulent dispersion coefficient of bubbles. Brief discussions are also presented on the accuracy of these techniques.     

ChemInform Abstract: Determination of the Space Group of LaCrO3 by Convergent‐Beam Electron Diffraction.

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