Film cooling on a convex wall: Heat transfer and hydrodynamic measurements for full and partial coverage

Turbine-blade cooling is an important issue for high-efficiency turbine engines, and discrete-hole injection is widely used as a cooling method. In the present study, detailed measurements were made of the heat transfer and hydrodynamics of a film-cooled flow on a convex wall, both for full and partial coverage. Two important parameters were altered: the blowing ratio, m, and the number of rows of injection holes. Three values of m were tested: m = 0.2, 0.4, and 0.6. In the blown region, m = 0.4 results in the lowest Stanton numbers of the three blowing ratios tested. This indicates that the value of m = 0.4 is near optimum on the convex wall from the point of view of cooling effect by injection. In the recovery region, Stanton numbers gradually approach the no injection values. Although the heat-transfer behavior during recovery from injection looks relatively complicated, the behavior of Stanton number can be explained in terms of two mechanisms: recovery from the thermal effect of injection and recovery from the turbulence augmentation. This interpretation of the data is supported by the hydrodynamic and temperture-profile measurements. For partial blowing cases, the data follow the full-coverage values inside the blown region. In the unblown region, both in the curved and in the flat plate, the effect of the number of blown rows is clearly seen. Hydrodynamic boundary-layer profiles were measured with the aid of a triple hot-water probe. Three mean-velocity components and six turbulence quantities were simultaneously measured, and inside the blown region strong three-dimensionality was observed

Prediction of postoperative hepatic insufficiency by liver stiffness measurement (FibroScan®) before curative resection of hepatocellular carcinoma: a pilot study

BACKGROUND: Liver stiffness measurement (LSM) using transient elastography (FibroScan((R))) reflects the degree of hepatic fibrosis. This prospective study investigated how well LSM predicts the development of hepatic insufficiency after curative liver resection surgery for hepatocellular carcinoma. METHODS: The study enrolled 72 consecutive patients who underwent a preoperative LSM to assess the degree of liver fibrosis followed by curative liver resection surgery for hepatocellular carcinoma between July 2006 and December 2007. The primary end point was the development of hepatic insufficiency. RESULTS: The mean age of the patients was 54.9 years. Twenty patients (27.7%) had chronic hepatitis and 52 (72.3%) had cirrhosis (44 and 8 patients showed Child-Pugh class A and B, respectively). The mean LSM was 17.1 kPa. Twelve patients (16.6%) had segmentectomy only, 16 patients (22.2%) had bisegmentectomy, and 44 patients (61.2%) had lobectomy. Nine patients (12.5%) had stage I tumor, 56 (77.7%) had stage II, and 7 (9.8%) had stage III. Univariate and subsequent multivariate analyses revealed that preoperative LSM was the only independent risk factor for predicting the development of postoperative hepatic insufficiency (cutoff, 25.6 kPa; P = 0.001; relative risk, 19.14; 95% confidence interval, 2.71-135.36). CONCLUSIONS: LSM is potentially useful to predict the development of postoperative hepatic insufficiency in patients with hepatocellular carcinoma undergoing curative liver resection surgery.ope

A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats

Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and 4th lumbar vertebrae were analyzed by peripheral quantitative computed tomography (pQCT), microfocused X-ray computed tomography (micro-CT), histology, histomorphometry, Raman spectroscopy, and the three-point bending test. Contrary to our expectation, the exacerbation was very much limited to the cancellous bone parameters. Parameters of femur and tibia cortical bone were affected by the forced inactivity but not by OVX: (1) cross-sectional moment of inertia was significantly smaller in Sham-Inactive rat bones than that of their walking counterparts; (2) the number of sclerostin-positive osteocytes per unit cross-sectional area was larger in Sham-Inactive rat bones than in Sham-Walking rat bones; and (3) material properties such as ultimate stress of inactive rat tibia was lower than that of their walking counterparts. Of note, the additive effect of inactivity and OVX was seen only in a few parameters, such as the cancellous bone mineral density of the lumbar vertebrae and the structural parameters of cancellous bone in the lumbar vertebrae/tibiae. It is concluded that the lack of daily activity is detrimental to the strength and quality of cortical bone in the femur and tibia of rats, while lack of estrogen is not. Our inactive rat model, with the older rats, will aid the study of postmenopausal osteoporosis, the etiology of which may be both hormonal and mechanical

Predicting algal growth inhibition toxicity: three-step strategy using structural and physicochemical properties

<p>We propose a three-step strategy that uses structural and physicochemical properties of chemicals to predict their 72 h algal growth inhibition toxicities against <i>Pseudokirchneriella subcapitata</i>. In Step 1, using a log <i>D</i>-based criterion and structural alerts, we produced an interspecies QSAR between algal and acute daphnid toxicities for initial screening of chemicals. In Step 2, we categorized chemicals according to the Verhaar scheme for aquatic toxicity, and we developed QSARs for toxicities of Class 1 (non-polar narcotic) and Class 2 (polar narcotic) chemicals by means of simple regression with a hydrophobicity descriptor and multiple regression with a hydrophobicity descriptor and a quantum chemical descriptor. Using the algal toxicities of the Class 1 chemicals, we proposed a baseline QSAR for calculating their excess toxicities. In Step 3, we used structural profiles to predict toxicity either quantitatively or qualitatively and to assign chemicals to the following categories: <i>Pesticide</i>, <i>Reactive</i>, <i>Toxic</i>, <i>Toxic low</i> and <i>Uncategorized</i>. Although this three-step strategy cannot be used to estimate the algal toxicities of all chemicals, it is useful for chemicals within its domain. The strategy is also applicable as a component of Integrated Approaches to Testing and Assessment.</p