Crystal faces with no strong bonds along them are atomistically rough under equilibrium conditions. The growth of such faces has been considered to be governed by an adhesive growth mechanism. In the present study, the growth of such a face of a two-dimensional crystal is investigated based on a concept of crystal growth where, under certain conditions, the incorporation of growth units onto kink sites by a series process via step sites can be faster than the direct incorporation. This concept reveals a new growth mechanism similar to the two-dimensional nucleation-growth. The new mechanism predicts that surface structure can change from rough under equilibrium conditions to smooth in growth and dissolution processes, resulting in kinetic smoothening. The new mechanism also offers a general explanation of growth habit change from one polyhedral shape to another, something which could not be explained by the published theories of growth in pure systems.
A high pressure polymorph of clinoenstatite (HP-CEn) was studied using molecular dynamics (MD) simulations, based on empirical potential parameters. Starting from the MD-simulated structure of high-temperature clinoenstatite (HT-CEn) at 2000K and 0GPa, the subsequent MD calculations were carried out by increasing pressures up to 18GPa at intervals of 3GPa. Above 15GPa the MD-simulated crystals are HP-CEn characterized by their notably small β angles (99-100 degrees). Structure factors calculated from the resulting atomic positions reveal that the MD-simulated HP-CEn has a C2/c symmetry in common with the HT-CEn. The discontinuous change of the MD-simulated cell parameters with conspicuous hystereses between HT-CEn and HP-CEn, which implies a first-order phase transition, was first found in the present paper and suggests that the two clinoenstatites belonging to the same space group are two separated phases with large and small angles of the chain extension.
The photoreaction behaviors of various muconic derivatives, dialkyl (Z, Z)-muconates (1), N, N'-dialkyl-(Z, Z)-muconamides (2), and di(alkylammonium) (Z, Z)-muconates (3) in the crystalline state were investigated. The crystals of these compounds provided the corresponding (E, E)-isomers or tritactic polymers as the photoproducts during irradiation using a high-pressure mercury lamp, depending on the structure of alkyl substituents. The isomerization and polymerization were revealed to proceed via a crystal-to-crystal process based on the powder X-ray diffraction. The ammonium derivatives with higher n-alkyl substituents were found to have a high polymerization reactivity to yield a polymer with a meso-diisotactic-trans-2, 5-structure and high molecular weight, similar to the polymerization of the previously reported diethyl ester.
Cholesterol-bearing pullulan (CHP) underwent self-aggregation in water to form hydrogel nanoparticle. On the other hand, neocarzinostatin chromophore (NCS-chr) is separated from the apoprotein of intact neocarzinostatin (NCS) in 0.5M AcONa/AcOH (pH 4.7) in the dark. Complex formation between NCS-chr and the hydrogel nanoparticle of CHP was studied by high performance size exclusion column chromatography (HPSEC), UV-vis spectra, fluorescence spectra, and gel electrophoresis. The complex so obtained was water soluble enough. One hydrogel nanoparticle complexed with approximately 38 NCS-chr molecules. The complex showed the activity to cleave DNA strand of the plasmid. When the actual NCS-chr concentration of the complex was above 11.8μM, circular supercoiled pBR322 plasmid DNA form I was certainly converted to the circular relaxed form II and then to the linear form III. The complexed NCS-chr was stable even for three months under storage at 195K in the dark. Even after heating at 365K, more than ninety percent of NCS-chr still remained in the complex. This is the first example of showing that the simple nonprotein macromolecule, the self-aggregate of a hydrophobized polysaccharide, can nicely substitute for the apoprotein of NCS.
Lately the permanent-magnet-excited synchronous motor is replacing the DC control motor. However, it seems that investigation and analysis of PMSM have not been made adequately and sufficiently. In this paper SV method will be applied to analysis of PMSM, to obtain a new steady state vector diagram, which will reveal new aspects of performances of PMSM. They will provide superior characteristics to control of PMSM.
This paper theoretically presents the effective measure of plastic strain control, which has an advantage to describe the strain softening behavior unconditionally. An elasto-plastic constitutive model for geomaterials is formulated on the plastic strain rate space. The proposed model has an additional plastic deviatoric strain hardening parameter as the extended form of the modified Cam clay model. The description of strain softening succeed by the approximate plastic strain control and the softening mode is diversified with the magnitude of applied plastic strain. The stabilization of mechanical unstable behavior can be shown and the new interpretation of stability problem is discussed.
The nucleus intercollicularis (ICo) is a critical region for avian vocalization. Implantation of a testosterone pellet into a specific area in the midbrain of Japanese quail chicks rapidly alters their vocal behavior to crowing from distress calling. The speed with which this change occurs cannot be accounted for by the genomic action of testosterone. We found and purified testosterone binding proteins in the membrane of neurons within the ICo. We suggest that this protein mediates the action of testosterone on vocal behavior. This is the direct evidence that neural membrane protein mediates the action of steroid hormones.
Regional differences of noradrenergic innervation and noradrenergic α2 receptor distribution in the submucous plexus of guinea-pig caecum, large intestine, and rectum were investigated with immunofluorescence confocal microscopy. In the caecal submucous plexus, three dimensional basket-like arrangements of small and bright dots of tyrosine hydroxylase-like immunoreactivity (TH-LIR) were observed, whereas noradrenergic α2A receptor-like immunoreactivity (NAR-LIR) was detected in somata. Both TH-LIR and NAR-LIR were localized in neuronal somata of the transverse colon. A few TH-LIR positive cell somata and many TH-LIR positive spots forming chains passing through ganglia and interganglionic nerve strands were observed, but no NAR-LIR were seen in the submucous plexus of the descending colon. There were a few TH-LIR positive somata and puncta, but no NAR-LIR were observed in the ascending colon and rectum. All of these observations show the distinct regional differences in noradrenergic innervation and noradrenergic α2A receptor distribution in the guinea-pig submucous plexus.
An attempt was made to confirm and develop the work of Kuwayama et al. (J. Biochem. 104, 862-866, 1988) which showed a significant discrepancy between myosin light chain kinase (MLCK) activity (K-activity) and actomyosin-activating activity (L-activity) of bovine stomach. A simple method of preparing 155 kDa protein identical with MLCK was presented. Preparations thus obtained showed high ratios of the L-activity to the K-activity, the highest being 230. This indicates that a mechanism other than the phosphorylation of light chain plays a crucial role on the molecular level in activating contractile processes of the actomyosin-ATP system.
The aim of this work was to observe at electron microscopic level acetylcholinesterase (AChE) activity of frog neuromuscular junction revealed by an histoenzymatic reaction made on living tissues. In this purpose, Karnovsky's histochemical medium was used for the detection of AChE activity at concentrations ten times more diluted than in the original method. The medium was dissolved in Ringer solution containing citrate buffer, a chelating agent of cupric ions, and additional calcium chloride. Living nerve muscle preparation of the bullfrog was incubated in this histochemical Ringer solution. The muscle activity in response to electrical stimulation of motor nerve (0.1Hz) was monitored by recording of muscular contraction. The incubation was not prolonged beyond 15min, since a blockade of the neuromuscular transmission steadily occurred at that time. The tissue remained alive, however, since transmission was recovered by washing with fresh Ringer solution containing citrate buffer and additional calcium chloride. The primary histochemical precipitates endowed with oxidoreductase-like activity were revealed by secondary incubation with diaminobenzidine (DAB) and hydrogen peroxide. After osmification, osmium black of DAB gave fine localization of AChE activity in the synaptic cleft under the electron microscope.
One of the big problems in xenotransplantation from pigs to humans is the hyperacute immune reaction due to the carbohydrate epitope of Galα1-3Gal. Based on the porcine α-1, 3-galactosyltransferase cDNA sequence, several antisense oligonucleotide DNAs (20-base pair phosphorothioates) were chemically synthesized and used to suppress the expression of the Galα1-3Gal carbohydrate epitope on the surface of a porcine kidney cell line. One of the antisense oligonucleotide cDNAs including the stop colon of the sequences, caused a significant 30 to 35% decrease in the level of expression compared to in untreated cells. However, the treatment had no effect on cell growth and exhibited no toxicity. In contrast, the corresponding sense oligonucleotide or other antisense oligonucleotides containing the 5'-start colon had no effect on the carbohydrate expression. The binding of cells to human serum was investigated after the effective antisense oligonucleotide treatment. Cells thus treated were less reactive to human IgG or IgM. This evidence strongly supported that natural antibodies contained in human serum became less reactive with these cells due to suppression of Galα1-3Gal carbohydrate epitope expression on the cell surface by antisense oligonucleotide treatment. These findings provide a basis for and a means of genetic manipulation of porcine α-1, 3-galactosyltransferase for future xenotransplantation studies.