Fabrication of Al matrix composite reinforced with submicrometer-sized Al<Subscript>2</Subscript>O<Subscript>3</Subscript> particles formed by combustion reaction between HEMM Al and V<Subscript>2</Subscript>O<Subscript>5</Subscript> composite particles during sintering

To fabricate an Al-V matrix composite reinforced with submicron-sized Al₂O₃ and Al_xV_y (Al₃V, Al₁₀V) phases, high energy mechanical milling (HEMM) and sintering were employed. By increasing the milling time, the size of mechanically milled powder was significantly reduced. In this study, the average powder size of 59 μm for Al, and 178 μm for V₂O₅ decreased with the formation of a new product, Al-Al₂O₃-Al_xV_y, with a size range from 1.3 μm to 2.6 μm formed by the in-situ combustion reaction during sintering of HEM milled Al and V₂O₅ composite powders. The in-situ reaction between Al and V₂O₅ during the HEMM and sintering transformed the Al₂O₃ and Al_xV_y (Al₃V, Al₁₀V) phases. Most of the reduced V reacted with excess the Al to form Al_xV_y (Al₃V, Al₁₀V) with very little V dissolved into Al matrix. By increasing the milling time and weight percentage of V₂O₅, the hardness of the Al-Al₂O₃-Al_xV_y composite sintered at 1173 K increased. The composite fabricated with the HEMM Al-20wt.%V₂O₅ composite powder and sintering at 1173 K for 2 h had the highest hardness.     

Studies of cardiac function and myocardial tissue characterization

The heart can be studied using ultrasound techniques. The shape of the heart, its chambers, wall thicknesses, wall tissue characteristics as well as motion of walls and valve leaflets are all diagnostic information. In addition, the blood velocity and its timing within the cardiac cycle is an important diagnostic tool. In the present paper focus will be limited to the analysis of the left ventricular function as observed with two-dimensional and three-dimensional echocardiography and the characteristics of backscattered ultrasound information from the left ventricular chamber wall. Function of the heart is often studied by observation of local wall motion or comparison of chamber volume in maximum and minimum shapes during the cardiac cycle (ejection fraction). Integrated backscatter from the wall is described in examples of cardiac transplantation and hypertrophy. Study of cyclic variation of frequency-dependent attenuation and integrated backscatter indicates that these are independent parameters.     

Accuracy aspects in multiphase flow metering using X-raytransmission

The composition of a mixture of several components flowing through a pipe can be determined by means of an X-ray transmission technique/analysis. We present some aspects of the theory relating to an application in which the component volume fractions of an oil, water, and gas mixture are determined. It will be shown that on fundamental grounds, this technique has its limits regarding the number of components that can be distinguished in relation to the achieved accuracy of the measured attenuation     

A new tool for studying the molecular architecture of the fungal cell wall: one-step purification of recombinant trichoderma beta-(1-6)-glucanase expressed in Pichia pastoris

We assessed the anesthetic properties of helium and neon at hyperbaric pressures by testing their capacity to decrease anesthetic requirement for desflurane using electrical stimulation of the tail as the anesthetic endpoint (i.e., the minimum alveolar anesthetic concentration [MAC]) in rats. Partial pressures of helium or neon near those predicted to produce anesthesia by the Meyer-Overton hypothesis (approximately 80-90 atm), tended to increase desflurane MAC, and these partial pressures of helium and neon produced convulsions when administered alone. In contrast, the noble gases argon, krypton, and xenon were anesthetic with mean MAC values of (+/- SD) of 27.0 +/- 2.6, 7.31 +/- 0.54, and 1.61 +/- 0.17 atm, respectively. Because the lethal partial pressures of nitrogen and sulfur hexafluoride overlapped their anesthetic partial pressures, MAC values were determined for these gases by additivity studies with desflurane. Nitrogen and sulfur hexafluoride MAC values were estimated to be 110 and 14.6 atm, respectively. Of the gases with anesthetic properties, nitrogen deviated the most from the Meyer-Overton hypothesis. Implications: It has been thought that the high pressures of helium and neon that might be needed to produce anesthesia antagonize their anesthetic properties (pressure reversal of anesthesia). We propose an alternative explanation: like other compounds with a low affinity to water, helium and neon are intrinsically without anesthetic effect.     

Skin-customized wearable device adhesive without skin damage

Wearable medical devices are gaining popularity owing to their potential for seamless integration with the human body and long-term monitoring of physiological activity. However, conventional adhesives were developed based on the assumption of healthy adult skin and may not account for variations in skin characteristics across different species, environments, and body parts. Consequently, the adhesive strength of wearable devices may significantly differ depending on the skin surface to which they are attached, potentially causing skin damage. In this study, we developed a customized wearable-device adhesive without skin damage by analyzing the characteristics of the skin surface based on oil and water content and roughness according to different species and parts. Our findings demonstrated that increased root-mean-square roughness of the skin surface led to reduced contact area and decreased adhesion force between the polydimethylsiloxane (PDMS) pad and skin surface. Surprisingly, hairless skin exhibited 1.5 times higher adhesion strength than hairy skin due to stronger molecular forces resulting from the higher surface energy of the skin. Additionally, the hole-patterned PDMS pad on sweaty skin displayed improved adhesion properties compared to the cylinder-patterned PDMS pad. Therefore, customized wearable adhesives provide an effective strategy for developing skin-damage-free wearable devices.     

Variance components analysis of carotid and femoral intima-media thickness measurements. REGRESS Study Group, Interuniversity Cardiology Institute of The Netherlands, Utrecht, The Netherlands. Regression Growth Evaluation Statin Study

B-mode ultrasound intima-media thickness (IMT) measurements of carotid and femoral arterial walls are used in atherosclerosis studies. In this study, the components contributing to IMT measurement variability in males with coronary artery disease were investigated by means of repeated B-mode ultrasound scans and repeated off-line video image analyses. For statistical analysis, a mixed-model analysis of variance was used. From sonographer data, it was shown that human subjects and their arterial wall segments contributed 75% of the total IMT measurement variability in this population. Inter-sonographer variance contributed 25%. The intra-sonographer variance was negligible (<1%). In off-line image analysis, variance components due to subjects and segments, inter-analyst variance, and residual fluctuation were 88%, < 1% and 11%, respectively. Intra-analyst variance was negligible (<1%). The major source of B-mode ultrasound IMT measurement variability finds its origin in subjects and their arterial walls. Although sonographers proved a lesser source of variability, in comparative studies they should enter a study well trained and should be randomly assigned to subjects. Follow-up examinations should preferably be done by the same sonographer. Off-line image analysis contributed little to IMT measurement variability.     

B-mode ultrasound assessment of pravastatin treatment effect on carotid and femoral artery walls and its correlations with coronary arteriographic findings: a report of the Regression Growth Evaluation Statin Study (REGRESS)

OBJECTIVES: In this B-mode ultrasound study we assessed pravastatin treatment effects on carotid and femoral artery walls and investigated the correlations between the state and evolution of peripheral and coronary atherosclerosis. BACKGROUND: The Regression Growth Evaluation Statin Study (REGRESS) was an 11-center, 2-year, double-blind, placebo-controlled, prospective study of 885 men with coronary artery disease (CAD) (total cholesterol 4 to 8 mmol/liter). The study primarily investigated pravastatin treatment effects on the coronary lumen. This report focuses on the 255 patients who participated in the REGRESS ultrasound study. METHODS: Carotid and femoral artery walls were imaged at baseline and at 6, 12, 18 and 24 months. Pravastatin treatment effect was defined as the difference in progression of the combined intima-media thicknesses (IMT) between treatment groups. RESULTS: Pravastatin treatment effects were highly significant (combined IMT: p = 0.0085; combined far wall IMT: p < 0.0001; common femoral artery far wall IMT: p = 0.004). Correlations between the IMTs of the arterial wall segments ranged from -0.17 to 0.81. Baseline correlations between IMT and percent coronary lumen stenoses ranged from 0.23 to 0.36. Baseline IMT correlated with the mean coronary segment diameter (r = -0.32, p = 0.001) and minimal coronary obstruction diameter (r = -0.27, p = 0.005). There were no individual correlations between IMT and coronary lumen variables (p > 0.30). CONCLUSIONS: Pravastatin treatment effects on carotid and femoral artery walls were observed. B-mode ultrasound imaging studies of peripheral arterial walls could not describe the state and evolution of the coronary lumen in the individual patient, but proved to be a highly suitable tool for the assessment of antiatherosclerotic properties of agents.     

Coagulation and fibrinolytic responses of human peritoneal fluid and plasma to bacterial peritonitis

Significantly higher (P < 0.05) thrombin-antithrombin III complex levels were found in the abdominal exudate of patients with peritonitis (median 5500 ng/ml) than in that of controls (median 89 ng/ml). In patients, peritoneal fluid concentrations of tissue and urokinase-type plasminogen activator were increased by factors of 65 and 10 respectively (P < 0.05). The concentration of plasminogen activator inhibitor (PAI) 1 was increased by a factor of about 800 (median 395 versus 0.5 ng/ml, P < 0.05). Despite markedly raised concentrations of PAI, peritoneal fluid displayed fibrinolytic activity as demonstrated by significantly increased (P < 0.05) concentrations of plasmin-alpha 2-antiplasmin complex (median 10,952 versus 57 ng/ml) and fibrin degradation products (median 40,360 versus 126 ng/ml). There was no correlation between plasma and peritoneal fluid concentrations. Intraabdominal coagulation and fibrinolysis are stimulated in the abdominal cavity of patients with bacterial peritonitis.