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Poly(p-phenylene benzobisoxazole) (PBO) nanofibers were prepared from commercially available PBO fiber by a simple downsizing process for the first time. Partial alkaline hydrolysis of the oxazole ring brought ionic functional groups onto the fiber surface, enabling the disintegration of the PBO fiber into nanofibers with the help of an electrostatic repulsive force. The obtained nanofibers, whose average diameter was 24 nm, were characterized by SEM, FT-IR, ζ-potential analysis, XRD, and TGA. They dispersed homogeneously in water due to the surface charges. Filtration allowed a PBO nanofiber sheet to be easily prepared from the homogeneous dispersion in water.

We introduce a simple preparation procedure for aramid nanofibers from Twaron fibers by using a downsizing process. Alkaline hydrolysis pretreatment brings ionic charges on the fiber surface, allowing facile disintegration of Twaron into nanofibers by virtue of the electrostatic repulsive force. Since the nanofibers can be dispersed homogeneously in water, the processability and formability of the polymer were improved. The resulting aramid nanofibers, having a high degree of physical performance, a uniform nanosized morphology, and a high surface-to-volume ratio, will expand the range of novel applications of aramid fibers.

Single crystals of Ni were irradiated with 137 MeV xenon ions (Xe10+) of fluences up to 4.9 × 1013 ions/cm2 below 13 K. After the irradiation, the X-ray cryostat with the specimens was transferred from an irradiation chamber to the X-ray diffraction equipment below 20 K. The results of X-ray diffuse scattering near Bragg reflections at low temperature indicate that the defects are located in cascades and suggest that a small amorphous zone exists within the cascade region. By the thermal annealing at 40 K corresponding to the recovery stage IA, the defects in the cascades rearrange.

We developed a reliable method of transferring specimens at low temperature after ion irradiation with a cryostat for X-ray diffraction measurements. Single crystal Ni specimens have been irradiated with heavy ions at 13 K. Transferring the irradiated specimens at low temperature without any warming up, defect structures were studied using X-ray diffuse scattering on annealing between 18 K and room temperature. We observed a q −4 -dependence of the diffuse scattering intensity after the irradiation and the results indicated that there were both vacancies and interstitial clusters, which were associated with a displacement cascade. With increasing the annealing temperature of the irradiated Ni, the interstitial dislocation loops grew at 200 K and the radius and number of those loops began to decrease below 300 K.

We present a principal technique on controlling p-type hetero-valent interface by introducing interface superlattice layer composed of ZnTe-ZnSe MQW structure. Optimum quantum structure of the new interface superlattice (10-layered ZnSe-ZnTe superlattice), designed based on effective-mass Schrodinger equation, has shown almost complete ohmic conduction of carrier (hole) transport in the hetero valent interface. This interface supper lattice have been applied successfully for the ZnSSe based PIN and APD devices on p-GaAs. The ZnSSe PIN photodiodes on p-GaAs has demonstrated very high external quantum efficiencies (>60% in violet (400 nm), ∼35% in ultraviolet (300 nm): without anti-reflection coating) and also extremely low dark current (

Nanoclusters with a diameter of 2–10 nm were deposited from highly pure Al and Al–50%Cu targets onto highly oriented pyrolitic graphite (HOPG) by pulsed laser ablation. The structures and atomic configurations of these nanoclusters were then investigated with atomic resolution using a scanning tunneling microscope. On the pure Al nanoclusters, hexagonal two-dimensional configurations were found over a large area around a three-dimensional nanocluster. These two-dimensional structures were oriented at 30° to the graphite lattice and the atomic distance was estimated to be 0.424 nm. On the other hand, two-dimensional atomic configurations were not observed around the Al–50%Cu nanoclusters and the atomic distance was almost the same as that of highly oriented pyrolytic graphite visible in the STM. Thus, the initial growth and structures were completely different between the two materials.

II-VI ZnSe (binary) and ZnSSe (ternary) widegap compound semiconductor based photovoltaic devices (p-i-n and avalanche photodiodes (APDs)) are developed for the blue-violet (460-400 nm) optical wavelength region by molecular beam epitaxial (MBE) growth. The ternary compound ZnSSe p-i-n structure photodiodes, grown with complete lattice matched condition on GaAs substrates, exhibit high external quantum efficiencies of 80-70% in the blue-violet optical region with extremely low dark currents (∼pA/mm 2 ), These diodes reveal stable and long-lived operation at 300 K. Also presented is ZnSe and ZnSSe based blue-violet APD devices, fabricated by precise defect control and process techniques. This new device has revealed large signal gain (G) of G = 50 for ZnSe, and G = 60 for the ZnSSe APD device under high electric field strength of (0.8-1.1) × 10 6 V/cm. Important device parameters, ionization coefficients of photo-injected electrons and holes, and device stability are also discussed.

We present II-VI wide bandgap semiconductor ZnSe and ZnSSe based blue-violet avalanche photo-diode (APD) operation grown on GaAs substrate by molecular beam epitaxy (MBE). Because of highly improved crystal quality of the active layer, the ZnSSe APD reveals stable and high avalanche gain (G ≥ 60) in the blue-violet optical region under high field operation condition (E = 1.15 x 10 6 V/cm) at room temperature (RT). High electric field induced ionization coefficients α (for electrons) and β (for holes) are determined as a function of electric field strength E(V/cm); α(E) = 1.7 × 10 7 exp (-4.9 × 10 6 /E) and β(E) = 3.7 × 10 6 exp (-4.0 × 10 6 /E).

The authors established a method of clarifying the three dimensional interrelationship among the mitral and tricuspid annuli, ascending aorta, main pulmonary artery, diaphragmatic surface of the heart (DS), and anterior thoracic wall, using four chamber view magnetic resonance imaging. This method was applied to measuring the parameters that restrict the size and shape of a total artificial heart (TAH) from three dimensional reconstructed images of six normal subjects. Assuming that the TAH is implanted on the diaphragm, which corresponds to DS, the width of the TAH is restricted to 7.6 cm, the transverse dimension of the cardiac base (D-B), and the height to 7.8 cm, the dimension from the DS to the center of the pulmonic annulus (DS-P1). Depth is restricted by the longitudinal dimension of the left ventricle projected on the DS (D-L). While D-L in early systole is 9.7 mm, in late systole D-L is reduced to 7.6 cm. The angle (DS) (AW) is 65.7 degrees; this is the angle between the DS and anterior thoracic wall that restricts the shape of the TAH. While these data in normal subjects may be useful for TAH implantation, in the patient with acute cardiac failure, further study of patients with chronic cardiac failure is necessary.

The ferromagnetic exchange splitting of the 3d electron band was found to play an important role in the physical nature of self-interstitial atoms in bec Fe. This effect is related to the problem of the large magnetic moment of Fe-N, in which the Fe-Fe atomic distance also plays an important role. The threshold energy for defect creation has been explained using a model d band in the series of transition elements. The anomalously low value for bec Fe is explained by considering the magnetic energy and the non-quenched orbitals of 3d band electrons. The interstitial migration temperatures of the transition metals, including the anomalously high value for bec Fe, are explained. The high interstitial migration temperature in rare-earth metals is also discussed in relation to the overlap of the 4f electron wave functions.

Ischemia reperfusion (IR) of the liver is a multifactorial process that, at least in part, is responsible for the morbidity associated with major liver surgery under occlusion of the portal triad with the Pringle maneuver, total vascular exclusion or after liver transplantation. Surgeons are confronted with IR injury (IRI) more often than they anticipate. Although the human body has its own defense system, understanding the pathophysiology of IRI is essential for the surgeon in preventing and/or treating the reperfusion injury in common clinical practice. Several endogenous mechanisms exist to overcome IRI and a large number of pharmacological agents have also been found to confer protection against ischemic injury in the liver. They either blocked the injurious pathways directly or they subjected the liver to preconditioning. Prostaglandins (PGs) are a group of compounds derived from unsaturated 20-carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase (COX) pathway. They are short-lived, hormone-like chemicals that regulate cellular activities on a moment-to-moment basis and are produced in most tissues of the body, although the liver has emerged as the major organ participating in the synthesis, degradation and elimination of arachidonate products of systemic origin. PGs are released through the prostaglandin transporter on the cell's plasma membrane. During the last decade intensive work on the cytoprotective effects of PGs on livers suffering from IRI have been well documented. Prostaglandins confer their protective effects on IR-injured livers mainly by inhibiting the generation of reactive oxygen species, preventing leukocyte migration, reducing the synthesis or production of membrane degradation products, improving hepatic insulin and lipid metabolism, and regulating the production of inflammatory cytokines and cell adhesion molecules. Production of PGs have been found essential also soon after partial hepatectomy for hepatocyte proliferation.

The c-erbB-2 proto-oncogene encodes a transmembrane protein which is highly homologous to epidermal growth factor receptor. Overexpression of this c-erbB-2 protein has been reported in many human carcinomas, including breast carcinoma. However, there have been few studies of the expression of c-erbB-2 in cholangiocarcinoma and hepatolithiasis, a condition occasionally associated with cholangiocarcinoma.In this study, we evaluated immunoreactivity for the c-erbB-2 protein in human cholangiocarcinomas (n = 47), hepatolithiasis (n = 20), fetal livers (n = 36) and normal adult livers (n = 6). In normal adult livers and fetal livers, expression of c-erbB-2 protein could not be detected in hepatocytes or intrahepatic biliary cells. In hepatolithiasis, there was overexpression of c-erbB-2 in 15/20 (75%). The expression was found with a membranous pattern on the proliferated intrahepatic bile ducts and proliferated intrahepatic peribiliary glands around the bile ducts containing stones. Hepatocytes were negative for c-erbB-2 protein. Moreover, the biliary cell expression of the c-erbB-2 protein correlated significantly with Ki67 labelling index. On the other hand, aberrant expression of c-erbB-2 was found in 33/47 (70%) cholangiocarcinomas. The c-erbB-2 expression in cholangiocarcinomas did not correlate with Ki67 labelling index or p53 expression.These results indicate that aberrant expression of c-erbB-2 protein is found in cholangiocarcinoma and also in noncancerous biliary proliferative lesions such as hepatolithiasis. These findings also suggest that c-erbB-2 oncogene participates not only in cholangiocarcinogenesis but also in biliary cell proliferation in non-neoplastic conditions.

We demonstrate a first simultaneous measurement of the real and imaginary parts of the refractive index of a highly turbid medium by observing the real-time reflectance profile of a divergent laser beam made incident on the surface of the turbid medium. We find that the reflectance data are well described by Fresnel theory that correctly includes the effect on total internal reflection of angle-dependent penetration into the turbid medium.

To evaluate the narrowing of the left ventricular outflow tract (LVOT) during systole caused by a rigid mitral prosthesis, the geometric relationship between the prosthesis (or the mitral annulus) and the left ventricular base (LVB) was studied in five patients with mechanical mitral valve prostheses and eight normal subjects. The images of the mitral valve annulus (MVA) and the LVOT orifice reconstructed in three dimensions were projected on the plane of the LV base. Calculating the areas of these projected images (i.e., those for MVA [Sm], LVOT orifice [So], the LVB [Sb; Sb = Sm + So]), the MVA-LVB ratio (Sm/Sb) was determined. In the normal subject, the MVA-LVB ratio was nearly constant during systole (59 +/- 5% at 0 msec and 62 +/- 7% at 300 msec, respectively), whereas in the patients with prostheses, the ratio increased from 61 +/- 4% (0 msec) to 69 +/- 4% (300 msec). The increase in MVA-LVB ratio reduces the proportionate share of LVOT orifice in relation to the total LVB. The ideal mitral valve prosthesis should be flexible at the annulus to attain good performance in LVB dynamics.

The thermal expansion of the lattice constant of a GaP crystal was measured in the range 4.2-300K using the Bond method. The authors found a negative thermal expansion coefficient for GaP at low temperatures. They also calculated the Gruneisen parameter and this was negative below 50K. These experimental results do not agree with the phenomenological theory in which a positive thermal expansion coefficient for GaP is predicted at low temperatures.

Left ventricular posterior wall movement in 20 patients with mitral stenosis (MS) was measured using M-mode echocardiogram in order to evaluate the improvement of myocardial function after open mitral commissurotomy (OMC) and compared between the cases with (10 patients) and without (10 patients) papilloplasty. The maximum left ventricular end-diastolic posterior wall velocity (LVPEVdmax) was increased from 71 +/- 12 to 90 +/- 16 mm/s in OMC patients (p less than 0.01) and from 59 +/- 19 to 101 +/- 28 mm/s in OMC + P patients (p less than 0.001). The maximum left ventricular systolic posterior wall velocity (LVPWVsmax) showed an increase from 51 +/- 9 to 62 +/- 10 mm/s in OMC patients (p less than 0.02) and from 48 +/- 10 to 69 +/- 8 mm/s in the OMC + P group (p less than 0.001). The mean LVPWVs increased from 35 +/- 8 to 48 +/- 8 mm/s in the OMC + P group (p less than 0.01). These parameters correlate fairly well with stroke volume index (SVI), ejection fraction (EF), and fractional shortening (FS) derived from internal LV dimensions. Thus, the posterior wall movement may prove to be useful as an index for evaluating the improvement of LV function after OMC.

As a prelude to clinical trials with a bovine surfactant (surfactant TA), in human infants with hyaline membrane disease, pulmonary and hemodynamic changes following its instillation in premature baboons were investigated. Baboons, delivered by cesarean section at 141 +/- 3.5 days (mean +/- SD, 77% gestation), were provided with intensive care. At 2 hours of age in one group (n = 10), 100 mg/kg of surfactant TA (reconstituted bovine surfactant, Tokyo Tanabe Co., Tokyo) was instilled into the lungs. Sequential measurements and monitoring of pulmonary and hemodynamic variables were carried out in these ten baboons and in a control group of five baboons for 16 hours, at which time the experiments were electively terminated. At birth, the pulmonary compliance, findings of chest radiographs, ratio of arterial PO2 to alveolar PO2, and respirator variables needed to maintain normal blood gas and acid base status were identical in both groups and indicative of severe hyaline membrane disease. Following surfactant instillation, the treated group demonstrated a rapid increase in PO2 with significantly improved ratio of arterial PO2 to alveolar PO2 (from a mean +/- SD pretreatment value of 0.21 +/- 0.11 to 0.45 +/- 0.11 by 16 hours). Pulmonary compliance improved similarly (from pretreatment value of 0.18 +/- 0.06 mL/cm H2O/kg to 0.27 +/- 0.09 mL/cm H2O/kg). Significant reduction in respirator support variables could be achieved in all treated animals; however, in the control animals, the pulmonary status worsened as evidenced by increasing mean airway pressure and respirator variables to keep normal blood gas and acid base status, thus worsening compliance. At autopsy, pulmonary pressure-volume curves were significantly different with large hysteresis obtained in the surfactant-treated group. Although no deleterious effect on hemodynamics was noted in surfactant TA-treated animals, a large patent ductus arteriosus was demonstrated by aortography. Increased lung blood flow, probably due to a large patent ductus arteriosus flow, was demonstrated by radiolabeled microsphere technique. The physiologic significance and clinical relevance of these findings in premature baboons treated with surfactant TA are discussed.