Deformation-induced phase transitions and superstructure formation in poly(ethylene terephthalate) (PET) were studied by means of in-situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) as well as Raman spectroscopy. The deformation conditions involved uniaxial stretching of quenched PET films at a temperature just below its glass transition temperature (T g), where a notable “plastic deformation” stage was observed. WAXD results indicated that the initial sample contained a “slush” structure (amorphous + nematic), whereby deformation induced oriented amorphous, nematic, smectic (C and quasi-A), and stable triclinic crystalline phases. SAXS results indicated that the fibrillar superstructure was formed upon the formation of oriented slush. In-situ Raman spectroscopic data revealed the orientation information on ethylene glycol and benzene ring as well as the gauche − trans transition in deformation of PET chains, which are in good agreement with X-ray results. A mechanism for deformation-induced phase transitions and for hierarchical structure formation has been proposed to correlate the structural information with the mechanical properties.

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Vulcanizates of natural rubber (NR) and its synthetic analogue (IR) were quickly stretched to 6 times the original length. The post stretch relaxation of tensile stress and the development of strain-induced crystallization (SIC) were studied by simultaneous measurements of the stress and the diffraction intensities using the synchrotron X-ray source. In the range of 8 s, NR crystallized much faster than IR. Accordingly, the origin of the superior toughness of NR was thought to come from the ability of rapid SIC. Time constants of the poststretch crystallization were estimated from the X-ray study. Then the crystallization time constants were used to decompose the contribution of SIC from the total magnitude of the post-stretch relaxation. The contribution of SIC was dominant for the total magnitude of the post-stretch relaxation during several seconds.

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The evolution of superstructure and its relationship with the phase transition during uniaxial deformation of poly(ethylene terephthalate) (PET) at temperatures (90 and 100°C) above its glass transition temperature were investigated by in-situ small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). It appears that deformation at lower temperatures enhances the metastability of mesophase but narrows the strain window for phase transition. Very similar superstructure evolution pathways were observed at both temperatures. In zone I (the plastic deformation zone), WAXD did not show any crystal diffraction peak; however, SAXS exhibited an equatorial streak at the later stage, indicating the formation of a microfibrillar structure. Strain hardening took place in zone II, which could be categorized in two substages. In zone II-a, SAXS showed an X-shaped pattern that coincided with the appearance of crystal diffraction peaks in WAXD. The initial X-shaped patterns possessed strong intensity near the beam stop; the later patterns exhibited a scattering maximum that shifted toward larger angles with increasing strain. Results indicated the formation of a tilted lamellar structure within the microfibrils in conjunction with lamellar insertion. In zone II-b, oval spots appeared at the edges of the X-shaped pattern, which essentially became four-point. In this stage, the crystallinity still increased linearly with strain, but the invariant gradually reached an asymptotic value, indicating that lamellar insertion took place at a slower rate. In the final strain-hardening zone (III), the load became linear with strain even though crystallization was reduced. The equatorial long period was found to decrease drastically, suggesting that some microfibrils were split. In addition, a two-point pattern appeared near the central streak, corresponding to a periodic structure with long period of 100 nm. The formation of such a large layered structure and the microfibrillar splitting can be attributed to structural defects such as kinks in microfibrils.

alpha1-Acid glycoprotein (AGP) showed multiple peaks on separation using capillary electrophoresis in a chemically modified capillary with dimethylpolysiloxane at slightly acidic conditions. We analyzed glycoforms of AGP species after separation by ion-exchange chromatography, Con A affinity chromatography, and Cu(II)-chelating affinity chromatography. The AGP species thus obtained were digested with N-glycosidase F, and the released carbohydrate chains were analyzed by high-performance liquid chromatography after labeling with 3-aminobenzoic acid. The results afforded basic information on the contribution of carbohydrate chains to the separation mechanism of glycoforms of AGP by capillary electrophoresis. In addition, we describe an easy method for AGP analysis in serum samples using the electrokinetic injection.

Long-term depression (LTD) of excitatory transmission at cerebellar parallel fibre-Purkinje cell synapses is a form of synaptic plasticity crucial for cerebellar motor learning. Around the postsynaptic membrane of these synapses, B-type γ-aminobutyric acid receptor (GABA B R), a G i/o protein-coupled receptor for the inhibitory transmitter GABA is concentrated and closely associated with type-1 metabotropic glutamate receptors (mGluR1) whose signalling is a key factor for inducing LTD. We found that in cultured Purkinje cells, GABA B R activation enhanced LTD of a glutamate-evoked current (LTD glu ), increasing the magnitude of depression. It has been reported that parallel fibre-Purkinje cell synapses receive a micromolar level of GABA spilt over from the synaptic terminals of the neighbouring GABAergic interneurons. This level of GABA was able to enhance LTD glu . Our pharmacological analyses revealed that the βγ subunits but not the α subunit of G i/o protein mediated GABA B R-mediated LTD glu enhancement. G i/o protein activation was sufficient to enhance LTD glu . In this respect, LTD glu enhancement is clearly distinguished from the previously reported GABA B R-mediated augmentation of an mGluR1-coupled slow excitatory postsynaptic potential. Baclofen application for only the induction period of LTD glu was sufficient to enhance LTD glu , suggesting that GABA B R signalling may modulate mechanisms underlying LTD glu induction. Baclofen augmented mGluR1-coupled Ca 2+ release from the intracellular stores in a G i/o protein-dependent manner. Therefore, GABA B R-mediated LTD glu enhancement is likely to result from augmentation of mGluR1 signalling. Furthermore, pharmacological inhibition of GABA B R reduced the magnitude of LTD at parallel fibre-Purkinje cell synapses in cerebellar slices. These findings demonstrate a novel mechanism that would facilitate cerebellar motor learning.