Acoustic roles of the laryngeal cavity in vocal tract resonance

The acoustic effects of the laryngeal cavity on the vocal tract resonance were investigated by using vocal tract area functions for the five Japanese vowels obtained from an adult male speaker. Transfer functions were examined with the laryngeal cavity eliminated from the whole vocal tract, volume velocity distribution patterns were calculated, and susceptance matching analysis was performed between the laryngeal cavity and the vocal tract excluding the laryngeal cavity (vocal tract proper). It was revealed that the laryngeal cavity generates one of the formants of the vocal tract, which is the fourth in the present study. At this formant, the resonance of the laryngeal cavity (the 1/4 wavelength resonance) induces the open-tube resonance of the vocal tract proper (the 3/2 wavelength resonance). At the other formants, on the other hand, the vocal tract proper acts as a closed tube, because the laryngeal cavity has only a small contribution to generating these formants and the effective closed end of the whole vocal tract is the junction between the laryngeal cavity and the vocal tract proper.     

Effect of water content on the glass transition and textural properties of hazelnut

This study is based on the assumption that the change in the texture of hazelnut, induced by water sorption or desorption, can be derived from the glass transition. No previous study has investigated the glass transition properties of hazelnuts. This study aimed to investigate the effect of water content on the glass transition and textural properties of a roasted hazelnut product. Water content of the sample was adjusted in various relative humidity conditions, and the mechanical glass transition temperature T_g was investigated using thermal rheological analysis (TRA), a type of thermomechanical analysis. The TRA curve exhibited a clear force drop induced by the glass transition, and mechanical T_g of the samples was determined. Water plasticizing effect caused mechanical T_g to decrease as the water content increased. The reduction in T_g was analyzed using the Gordon–Taylor equation and linear equation, and the critical water contents (water content at mechanical T_g?=?25 °C) were obtained. The fracturing properties of the hazelnut changed from brittle to ductile at the critical water contents. This suggested that the change in the texture of hazelnut can be characterized by the glass transition.

     

Towards beyond-1 GHz solution NMR: internal 2H lock operation in an external current mode

We have commenced a project to develop a beyond-1 GHz solution NMR spectrometer using a HTS coil. Due to a small residual resistance present in the HTS conductor and joint resistance between conductors, a stable persistent current sufficient for NMR measurements is unlikely. Therefore, a current has to be supplied to the HTS coil from an external power supply. The ripple of an external power supply causes a field fluctuation which must be stabilized. In this study we show results of NMR measurements using a 500-600 MHz NMR in such an external current mode: the field fluctuations are stabilized by an internal 2H lock. The field fluctuation from the external power supply comprises a major field fluctuation component at low frequencies, 0.003-0.005 Hz, and superimposed minor field ripples at 2 Hz and 50 Hz. The former limits the time interval of the internal 2H lock, while the latter generates sidebands in the NMR spectrum. Sideband and baseline noise are controlled by appropriate selection of the feedback loop parameters of the lock. The quality of the 1D-solution NMR spectra observed in external current mode is equivalent to that obtained in persistent current mode. However, if the feedback loop time is as short as the gradient pulse width, refocusing of the NMR signal is lost and NMR peaks disappear. The 2D-NOESY and the 2D-HSQC spectra of ubiquitin in an external current mode have been acquired. The quality of the 2D spectra is equivalent to those obtained in persistent current mode; i.e. the internal 2H lock operates stably over an experimental time interval of 40-50 min. To realize a beyond-1 GHz NMR spectrometer, further investigations must be made of (i) the long term stability of a DC power supply, (ii) the enhancement of the compensation field limit for the internal 2H lock, (iii) the extension of the helium refill time interval, and (iv) a method to correct the field homogeneity in the external current mode.     

Ge-doped InxGa1−xAs p−n junctions

The amphoteric properties of Ge in the In_xGa_1?xAscrystals grown by liquid-phase epitaxy are reported. It was found from the Hall measurements that when x < 0·1, the Ge-doped In_xGa_1?xAs was p-type, and when x > 0.1,it was n-type . At the vicinity of x = 0.1, therefore, the In_xGa_1?xAs p?n junction could be made by one growth process. The electrical and photoelectric characteristics of that junction were investigated. The distribution of Ge concentration at the p?n junction, which was obtained from the C-V characteristics, depended on the doping concentrations of Ge. This dependence can be interpreted by analyzing a modified Longini-Green equation. The spectral responses of both photovoltaic effect and electroluminescence showed that in In_0.1Ga_0.9As, Ge atoms gave rise to a heavy compensation effect, and introduced a conduction band tail of states and two kinds of acceptor levels located ～ 20and～ 100meV above the valence band edge.     

Effects of mercaptides on the butyllithium-initiated polymerization of methyl methacrylate

The effect of mercaptides on the butyllithium-initiated polymerization of methyl methacrylate in toluene were investigated. The rates of polymerization were decreased by the addition of mercaptides, possibly owing to the formation of a relatively stabilized complex between the mercaptides and the active center of the polymerizing monomer. The stereoregularity was also affected by the addition of mercaptides. The effects increased in the order of increase in the bulk of the alkyl group of the mercaptides: n-propyl < isopropyl < tert-butyl < phenyl. The effects of mercaptides on the stereoregularity were larger than those of the analogous oxygen compounds. The concentrations of butyllithium and monomer had no effect on the stereoregularity.     

HRTEM image contrast and atomistic microstructures of long-period ordered Al-rich TiAl alloys

Long-period superstructures formed in off-stoichiometric L 1(0)-TiAl alloys were investigated by high-resolution transmission electron microscopy (HRTEM). The HRTEM analysis combined with multislice simulation and image processing was carried out to clarify atomistic microstructures of Al5Ti3 and h-Al2Ti ordered states and a short-range ordered (SRO) state in Ti-62.5 at.% Al alloys. Aluminium atoms in the (002) Ti layers form square-, lean rhombus- and fat rhombus-type ordered clusters in the SRO state. The ordered clusters are in contact with each other and form microdomains of various long-period superstructures. The ordered clusters are tiled periodically in a long range to form Al5Ti3 or h-Al2Ti domains and characteristic antiphase boundary structures.     

Selectivity control of carbonylation of methanol to dimethyl oxalate and dimethyl carbonate over gold anode by electrochemical potential

New and unique electrocatalysis of gold for the carbonylation of methanol to dimethyl oxalate (DMO) and dimethyl carbonate (DMC) was found. The selectivity to DMO and DMC could be controlled over gold anode by electrochemical potential, as you like. Drastic changes of gold electrocatalysis was due to changes of the oxidation state of gold, Au0 or Au3+.