Recovery of cardiac function by long-term left ventricular support in patients with end-stage cardiomyopathy

Effects of long-term left ventricular (LV) support on end-stage cardiomyopathy patients is unclear. We applied our LV assist system (LVAS) to six heart transplant candidates, aged 17 to 49, with dilated cardiomyopathy, including one dilated phase hypertrophied cardiomyopathy. LVAS was installed between the left atrium and the ascending aorta, and the pump was positioned parecorporeally. In all patients, their general condition improved, and their pump flows were kept at 4 to 5 L/min. Exercise was started after stabilization of their general condition under constant pump flow. Natural heart size and function were examined by echocardiography. In the beginning of assist, all patients showed impaired cardiac function and LV dilation. During LV assist, systolic function measured by ejection time improved in all patients. Left ventricular end-diastolic dimension (LVDd), showed a remarkable decrease in two patients, who were weaned from LVAS after 3 months of support. They are doing well more than 1 year and 3 years after removal; peak VO2 levels (ml/min/kg) were 30 at 1.2 years and 27 at 2.7 years after removal. In the other four patients, however, LVDd had no remarkable changes, and three could not be weaned from LVAS. The last was discontinued from LVAS after 5 months of support because of infection and died 2 months after removal. From this experience, long-term LVAS may provide the chance for recovery of the natural heart in patients with end-stage cardiomyopathy. The patients whose hearts showed remodeling were able to be weaned from LVAS, and their heart function maintained in good condition for several years.     

An interpretation of ductile fracture process of uncrosslinked polymers in the rubbery state

The weak network theory previously developed is applied to explain the failure envelope for the ductile fracture of uncrosslinked amorphous polymers in a constant rate of elongation, with the assumption that the reformed chain requires a lapse of time after its reformation to contribute to maintenance of the network structure. The chain that contributes to maintain the structure is called the ‘structure chain’. The criterion is used that the fracture occurs provided the apparent average force per one ‘structure chain’ reaches a certain critical value. The result agrees well with the failure envelope obtained experimentally.     

Effects of orientation and chemical structure on the strength properties of some polymers

The stress-strain properties of oriented polymers are measured parallel and perpendicular to the direction of hot stretching. The polymers include styrene-acrylonitrile copolymers, vinyl alcohol copolymers, acrylic acid copolymers, polyelecf trolytes, and a high density polyethylene. Polarity and hydrogen bonding tend to increase the strength, especially in the direction perpendicular to the direction of hot stretching. Strong electrostatic bonding in polyelectrolytes and too much polar bonding in styrene-acrylonitrile & polymers decrease the strength by reducing the molecular mobility, which is required to prevent brittleness.     

Stiffness of human arterial wall assessed by intravascular ultrasound

Little is known about the elastic properties of human arteries. Intravascular ultrasound (IVUS) can measure the instantaneous circumference or diameter of the arteries during a cardiac cycle, and so investigate human arterial elasticity in vivo. We studied 36 patients aged from 35 to 72 years classified into the ischemic heart disease (IHD) group (21 patients aged 39 to 71 years) and the non-ischemic heart disease (NIHD) group (15 patients aged 35 to 76 years) who had no atherogenic factors. The stiffness and wall morphology of six portions from the thoracic descending aorta to common iliac artery were measured by 8F, 15 MHz IVUS. The stiffness parameter, beta, was calculated as 1n (Pmax/Pmin)/(Cmax/Cmin-1), where P is arterial pressure, and C is the circumference of the artery. The thickness of the intima-media complex echo (Th) was used as a substitute for the wall thickness, and Th/D was calculated as an index of relative wall thickness, where D is the minimum luminal diameter. The pulse wave velocity (PWV) was measured with a conventional method. beta increased after branching of the renal artery and increased much more toward the periphery in comparison with the thoracic descending aorta in both groups. At all portions except the abdominal aorta after branching of the renal artery and the common iliac artery, beta was significantly larger in the IHD than the NIHD group. Th/D increased as well as beta in both groups. At all portions except after branching of the renal artery, Th/D was significantly larger in the IHD than the NIHD group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Linear InGaAsP edge-emitting LED's for single-mode fibercommunications

A 1.3-μm edge-emitting diode with a linear radiance and high coupled power into a fiber is described. The LED yields 60 μW of coupled power into a single-mode fiber at a driving current of 100 mA and an ambient temperature of 25°C. A V-groove structure with an optical absorption region separated from an active region is used. At active layer thicknesses below 0.14 μm, linear current-light output characteristics are obtained. The spectral modulation depth is 0% over the entire emission spectral width of 75 nm, and coherence length is 22.5 μm. LED characteristics are achieved in the range from -30 to 85°C at a driving current of 100 mA. The LEDs exhibit a cutoff frequency of 250 MHz. LED reliability is discussed using results of accelerated aging carried out at the ambient temperatures of 50, 125, and 200°C. The activation energy of degradation is determined to be 0.63 eV, and LED half-lives are estimated to be in excess of 10⁶ h     

Beh?et disease and the HLA system

Haemoglobin Lepore Washington is reported apparently for the first time in a white Australian male. Because some of this patient's family have similar blood changes it is assumed that they also have inherited the disorder.     

Simulation study of electrical dynamic characteristics of lithium-ion battery

The electrical dynamic characteristics of a lithium-ion battery have been simulated by an equivalent circuit, which is derived from the measured impedance. The transient voltage response to the various kinds of applied current waves such as single pulse, single rectangular, triangle, and sawtooth waves is experimentally examined and calculated by using the numerical Laplace transform with the equivalent circuit. The experimental and calculated results are compared and discussed, focusing on the range of current where the linear relationship is valid. Changing the time range, the state of charge (SOC) and the battery temperature as parameters, their influence on the linear range of the applied current has been investigated.     

Study on enhancement of condensation heat transfer using an electric field

Enhancement of condensation heat transfer using a nonuniform electric field was experimentally investigated for horizontal smooth and low‐finned tubes. In the experiments, a wire electrode parallel to the tube was placed beneath the tube. The experimental parameters were the distance and voltage between the wire electrode and the tube, and the condensation heat flux. Results of the present experiment for the low‐finned tube indicate that, as the applied voltage increases, the enhancement ratio increases steeply at a certain voltage and it reaches 2.4. It was observed that the condensate flow pattern falling down from the bottom of the tube changed from a flat film to circular columns at a critical voltage. © 2000 Scripta Technica, Heat Trans Asian Res, 29(4): 269–279, 2000