Comparison of distortion product otoacoustic emissions with auditory brain-stem response for clinical use in neonatal intensive care unit

PURPOSE: Kainic acid (KA) has long been used in experimental animals to induce status epilepticus (SE). A mechanistic implication of this is the association between excitotoxicity and brain damage during or after SE. We evaluated KA-induced metabolic impairment and the potential mitigating effects of GYKI 52466 [1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine] in superfused rat cerebral cortical slices. METHODS: Interleaved [31P]/[1H] magnetic resonance spectroscopy (MRS) was used to assess energy metabolism, intracellular pH (pHi), N-acetyl-L-aspartate (NAA) level, and lactate (Lac) formation before, during, and after a 56-min exposure to 4 mM KA in freshly oxygenated artificial cerebrospinal fluid (oxy-ACSF). RESULTS: In the absence of GYKI 52466 and during the KA exposure, NAA, PCr, and ATP levels were decreased to 91.1 +/- 0.8, 62.4 +/- 3.9, and 59.1 +/- 4.3% of the control, respectively; Lac was increased to 118.2 +/- 2.1 %, and pH, was reduced from 7.27 +/- 0.02 to 7.13 +/- 0.02. During 4-h recovery with KA-free ACSF, pHi rapidly and Lac gradually recovered, NAA decreased further to 85.5 +/- 0.3%, and PCr and ATP showed little recovery. Removal of Mg2+ from ACSF during KA exposure caused a more profound Lac increase (to 147.1 +/- 4.0%) during KA exposure and a further NAA decrease (to 80.4 +/- 0.5%) during reperfusion, but did not exacerbate PCr, ATP, and pHi changes. Inclusion of 100 microM GYKI 52466 during KA exposure significantly improved energy metabolism: the PCr and ATP levels were above 76.6 +/- 2.1 and 82.0 +/- 2.9% of the control, respectively, during KA exposure and recovered to 101.4 +/- 2.4 and 95.0 +/- 2.4%, respectively, during reperfusion. NAA level remained at 99.8 +/- 0.6% during exposure and decreased only slightly at a later stage of reperfusion. CONCLUSIONS: Our finding supports the notion that KA-induced SE causes metabolic disturbance and neuronal injury mainly by overexcitation through non-N-methyl-D-aspartate (NMDA) receptor functions.     

Delineation of calf deep veins using 2D-TOF MR venography without contrast media: efficacy of tourniquet and leg-warming]

We evaluated the imaging quality of 2D-TOF MR venography of the lower part of the leg and the efficacy of a tourniquet around the knee and leg-warming. In 8 healthy volunteers, MR venography was carried out under the following four conditions: (a) usual MR venography, (b) MR venography with tourniquet around the knee, (c) MR venography after leg-warming and (d) MR venography with tourniquet after leg-warming. Our results suggested that MR venography with tourniquet after leg-warming is best suited for imaging the veins of the leg. We also compared the diagnostic image quality of MR venography and conventional contrast venography in 7 patients with varices. The results showed no significant differences between the two methods. We conclude that MR venography with tourniquet after leg-warming is a technique that provides reliable information about the veins of the leg.     

Probability distribution applicable to non-Gaussian random processes

This paper presents a probability density function representing a non-Gaussian random process in closed form. The probability density is based on the Kac-Siegert solution of Volterra's stochastic series expansion of a nonlinear system. A method is developed, however, to obtain the Kac-Siegert solution from knowledge of the time history only of the random process, and the result is expressed as a function of a normal distribution. Then, by applying the change of random variable technique, the asymptotic probability density function applicable to the response of a nonlinear system (which is a non-Gaussian random process) is developed in closed form. A comparison of the presently developed probability density function and the histogram constructed from a record indicating strong non-Gaussian characteristics shows excellent agreement.     

An Automated Finite Polygon Division Method for 3-D Objects

The automatic generation of color-shading data for CAD/CAM objects can produce mass-property calculations in less time with fewer errors.     

Thermal and mechanical properties of tetra‐functional mesogenic type epoxy resin cured with aromatic amine

A novel tetra‐functional epoxy monomer with mesogenic groups was synthesized and characterized by ¹H‐NMR and FTIR. The synthesized epoxy monomer was cured with aromatic amine to improve the thermal property of epoxy/amine cured system. The glass transition temperature (T_g) and coefficient of thermal expansion (CTE) of the cured system were investigated by dynamic mechanical analysis and thermal mechanical analysis. The properties of the cured system were compared with the conventional bisphenol‐A type epoxy and mesogenic type epoxy system. The storage modulus of the tetra‐functional mesogenic epoxy cured systems showed the value of 0.96 GPa at 250 °C, and T_g‐less behavior was clearly observed. The cured system also showed a low CTE at temperatures above 150 °C without incorporation of inorganic components. These phenomena were achieved by suppression of the thermal motion of network chains by introduction of both mesogenic groups and branched structure to increase the cross linking density. The temperature dependency of the tensile property and thermal conductivity of the cured system was also investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46181.     

Image extraction of particle concentration at the plug front using 3D wavelets and comparison with LDV

Particle concentration distribution images of a dense two-phase solid/air (plug) flow have been obtained at 10-ms intervals in a horizontal pipeline using capacitance computed tomography. The three-dimensional images (time and two-dimensional space images) were decomposed to wavelet time levels to extract the dominant particle concentration distribution using three-dimensional discrete wavelet multiresolution. As a result, the time-dominant particle distribution with a specific time frequency level can be visualized in cross-section. In detail, the high concentration of the particle spatial distribution at the dense flow front, which composes high time frequency levels 6 and 7, is centrally located above the stationary layer. The distribution image at the front is reasonable when compared with the particle velocity distribution by conventional laser Doppler velocimetry (LDV) that indicates the discharging particles toward the front air phase at the centerline.     

The mechanism for occurrence of internal stress during curing epoxide resins

The mechanism for the occurrence of internal stress in the curing cycle of four-functional epoxide resins was investigated in detail. The internal stress in this system was generated at the vitrification point in the course of curing, because the modulus of samples was rapidly increased at this point. After the vitrification point, the internal stress was increased with an increase of the shrinkage in the curing and cooling processes. Moreover, the magnitude of the internal stress in the four-functional resin systems depended on the chemical structure of aromatic diamines used as curing agents. This was explained by the difference of curing shrinkage after vitrification in each system.     

Effect on the toughness and adhesion properties of epoxy resin modified with silyl-crosslinked urethane microsphere

In order to give a toughness and improve adhesion properties of the cured epoxy system, modified epoxy resins, which have pre-reacted urethane microspheres formed using dynamic vulcanization method in liquid diglycidylether of bisphenol A, were prepared. It was found that the size of the particles decreased to sub-micro order with increase in solubility of urethane oligomers in epoxy resin, and coefficient of variance in the particle size distribution resulted in less than 15%. Fracture energy G_1c of the cured system was highly improved. Lap shear strength and peel strength were also improved. These mechanical and adhesion properties do not depend on any curing condition of epoxy resin because of the existing stable particles in the epoxy resin before curing.     

Effect of the low-temperature relaxation on toughness of cured epoxy resins

The relation between the magnitude of low-temperature relaxation and toughness was investigated for epoxy resins cured with some position isomers of naphthalenediols. A well-defined relaxation was observed near room temperature for a system cured with 2,6-dihydroxynaphthalene. The relaxation was denoted here as the β′-relaxation. The values of the stress intensity factor, K_c, in this system was considerably higher than those of the other cured systems in the temperature region over the β′-relaxation temperature. This is explained by the increase in the plastic deformation region at the crack front with an increase in the temperature near the crack tip caused by the presence of the β′-relaxation. © 1994 John Wiley & Sons, Inc.     

Thermal conductivity of homogeneous alignment networks formed with mono‐ and bi‐functional polymerizable liquid crystals

Mixtures consisting of mono‐functional polymerizable liquid crystals (PLC) having a polymerizable moiety on the molecular short axis terminal and a bi‐functional PLC having the polymerizable moieties on the molecular long axis terminals were prepared. These mixtures had a wide liquid crystal range. Uniaxially aligned films were prepared from the PLC mixtures by photo polymerization after aligning the molecular directions by the rubbing method. The thermal conductivity of the films increased from 0.45 to 0.68 W/m · K with the increase ofthe content of the bi‐functional PLC. The relation between the thermal conductivity and the PLC network styles was investigated from the aspect of the molecular order. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007