Development of Ti-6Al-4V and Ti-1Al-8V-5Fe Alloys Using Low-Cost TiH2 Powder Feedstock

Thermo-mechanical processing was performed on two titanium alloy billets, a beta-titanium alloy (Ti1Al8V5Fe) and an alpha-beta titanium alloy (Ti6Al4V), which had been produced using a novel low-cost powder metallurgy process that relies on the use of TiH₂ powder as a feedstock material. The thermomechanical processing was performed in the beta region of the respective alloys to form 16-mm diameter bars. The hot working followed by the heat treatment processes not only eliminated the porosity within the materials but also developed the preferred microstructures. Tensile testing and rotating beam fatigue tests were conducted on the as-rolled and heat-treated materials to evaluate their mechanical properties. The mechanical properties of these alloys matched well with those produced by the conventional ingot processing route.     

Productivity and water use efficiency of sweet sorghum (Sorghum bicolor (L.) Moench) cv. “Keller” in relation to water regime

Sweet sorghum (Sorghum bicolor (L.) Moench) has been recognized as an alternative crop for energy purposes. In the central area of the Iberian Peninsula, its main growth period coincides with the dry season and irrigation is needed for reasonable sorghum productivity. Knowledge of irrigation-yield relationships is fundamental, since water is a scarce resource there. Our objectives in this work were to study the effect of water regime on the productivity and water use efficiency (WUE) in a sweet sorghum cultivar “Keller” grown in lysimeters in Madrid. Experiments were carried out during three crop cycles. Three irrigation regimes: H₁, H₂ and H₃, corresponding to a water supply of 5.7, 11.4 and 17.1 dm³ m⁻² day⁻¹ were experimented with during the main growth period. Maximum aerial biomass production was 4.0 10³g DM m⁻² in the H₃ regime. WUE was quite similar for every irrigation regime but varied between sorghum seasons. 4.6 g aerial biomass DM dm⁻³ was obtained as the average for a crop cycle length of approximately 130 days. The water regime did not clearly affect the sugar content in stalk sections. The mean value of sugar content in whole stalks was 41.4% w/w on a dry-weight basis. The ratio of ethanol production to evapotranspired crop water was estimated at 0.63 g dm⁻³ (mean value).     

Relationship between clinical assessments of function and measurements from an upper-limb robotic rehabilitation device in cervical spinal cord injury

Upper limb robotic rehabilitation devices can collect quantitative data about the user's movements. Identifying relationships between robotic sensor data and manual clinical assessment scores would enable more precise tracking of the time course of recovery after injury and reduce the need for time-consuming manual assessments by skilled personnel. This study used measurements from robotic rehabilitation sessions to predict clinical scores in a traumatic cervical spinal cord injury (SCI) population. A retrospective analysis was conducted on data collected from subjects using the Armeo Spring (Hocoma, AG) in three rehabilitation centers. Fourteen predictive variables were explored, relating to range-of-motion, movement smoothness, and grip ability. Regression models using up to four predictors were developed to describe the following clinical scores: the GRASSP (consisting of four sub-scores), the ARAT, and the SCIM. The resulting adjusted R(2) value was highest for the GRASSP "Quantitative Prehension" component (0.78), and lowest for the GRASSP "Sensibility" component (0.54). In contrast to comparable studies in stroke survivors, movement smoothness was least beneficial for predicting clinical scores in SCI. Prediction of upper-limb clinical scores in SCI is feasible using measurements from a robotic rehabilitation device, without the need for dedicated assessment procedures.     

Impact of pulmonary rehabilitation on self-efficacy, quality of life, and exercise tolerance.

Objective: The objective of the present study was to investigate changes in psychological, physiological, and behavioral-performance variables as a function of pulmonary exercise rehabilitation. Study Design and Participants: Forty patients diagnosed with chronic obstructive pulmonary disease (COPD) were recruited for participation in a 12-week outpatient pulmonary rehabilitation program. Measures: Measures included 6-min walking distance (exercise tolerance), 6-min walking distance self-efficacy, overall quality of life, dyspnea, fatigue, and emotional function. Results: Results revealed significant improvements over the course of the program in each of these measures, regardless of disease severity. In addition, improvements in exercise tolerance were significantly associated with increases in self-efficacy, which, in turn, were significantly related to improved quality of life. Conclusions: The results support the tenets of social-cognitive theory and suggest that participation in an outpatient pulmonary rehabilitation program can provide both physiological and psychological benefits for individuals with COPD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling light reflection for computer color vision

In computer vision applications, analysis of shading information requires a proper model of light reflection from object surfaces. To overcome the shortcoming of the most often used model and to extend the reflection model for computer color vision, an examination is made of the light reflection problem using the bidirectional spectral-reflectance distribution function (BSRDF) to specify both incident- and reflected-beam geometries. It is shown that the product form can still be retained for a polychromatic light source under two lighting conditions: the light source is collimated; or the spectral factor and the geometric factor can be separated for both the light source and the BSRDF of the surface. The reflection model is then applied to the formulation of a neutral-interface-reflection model, which is tested experimentally. The results show the adequacy of this type of model for surfaces of some material compositions, e.g. plastics, plant leaves, painted surfaces, orange peels, and some glossy cloth, but not for others, e.g. colored paper and some ceramics     

What lies beyond E and N? Factor analyses of scales believed to measure basic dimensions of personality.

The study was designed to investigate the dimensions underlying some of the personality traits measured by questionnaires that have been used in research on the biological bases of personality. Forty-six scales from eight tests were selected to provide markers for seven hypothesized factors. Subjects were 271 students taking the tests as part of a personality course. Factor rotations were done for solutions that extracted three, five, or seven factors. Five of the seven postulated factors were found with the seven-factor rotation: sociability, activity, impulsivity, socialization, and emotionality. In the five-factor rotation, asocialization, impulsivity, and many elements of sensation seeking blended in a P factor, and anger and anxiety formed a broader emotionality factor. The three-factor solution approximates the model proposed by Eysenck, and his own scales provide excellent markers for the three factors. Correlations of factor scores derived from data for men and women and applied to data for the opposite sex show very good correspondence of factors at the three-factor level. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficiency differences in computational simulations of the total cavo-pulmonary circulation with and without compliant vessel walls

The Fontan operation is a palliative surgical procedure performed on children born with congenital defects of the heart that have yielded only a single functioning ventricle. The total cavo-pulmonary connection (TCPC) is the most popular variant of the Fontan procedure. The objective of the study was to quantify and compare the efficiency of numerical models of the TCPC with rigid versus elastic vessel wall models. The pressure drop and power loss through both type TCPC models was measured. Significant differences in efficiencies exist between rigid versus elastic numerical models. We have shown incorporating elasticity into numerical models of the total cavo-pulmonary connection is important when determining circuit efficiencies.     

Frequency distributions of water quality variables : Relationships between mean and maximum values

Frequency distributions of water quality variables have been analysed by using about 950 samples from 25 meso- to hypertrophic lakes. By expressing all values as relative to their means, data from all the lakes could be pooled to datasets based on about 950 values for each variable. The distributions of COD, conductivity, pH and colour were symmetrical with very high frequencies around 100% of the mean. The variables of total-N, total-P, suspended solids and Secchi disk transparency followed more skew distributions, while turbidity, chlorophyll a and MRP were markedly skewed. The inorganic nitrogen fractions had their highest frequency at or just above zero percent of the mean.Three probability density functions (pdf) namely beta, gamma and log normal distributions were fitted to the pooled data. There were two variables, colour and conductivity, which did not fit to any of the pdf's but for the rest the null hypothesis could not be rejected at the 99.5% level. Frequency distributions for each lake demonstrated that for most variables one or two lakes showed distributions deviating from the pooled data pdf. There were no discernible trends among lakes and the number of rejections seemed to be randomly distributed. The study is inconclusive but does not reject the approach of using frequency distributions of relative values when only the mean is known. Agreement between expected maxima and those observed by other investigators indicate that the log normal distributions estimated here might be generally applicable as a rule of thumb on what the maximum will be in relation to the mean. The results of this study also indicate that the frequency distributions are similar for a large variety of water quality in many lakes. This information is of great interest for water management as good approximation of maximum values might be achieved if the means are known.     

Enhanced channel modulation in dual-gated silicon nanowire transistors

Dual-gated silicon nanowire (SiNW) field-effect transistors (FETs) have been fabricated by using electron-beam lithography. SiNW devices (W approximately 60 nm) exhibit an on/off current ratio greater than 10(6), which is more than 3 orders of magnitude higher than that of control devices prepared simultaneously having a large channel width (approximately 5 microm). In addition, by changing the local energy-band profile of the SiNW channel, the top gate is found to suppress ambipolar conduction effectively, which is one of the factors limiting the use of nanotube or nanowire FETs for complimentary logic applications. Two-dimensional numerical simulations show that the gate-induced electrostatic control is improved as the channel width of the FETs decreases. Therefore, enhanced channel modulations can be achieved in these dual-gated SiNW devices.     

Microchip immobilized enzyme reactors for hydrolysis of methyl cellulose

Microchip immobilized enzyme reactors (microIMERs) with immobilized endoglucanases were applied for the hydrolysis of methyl cellulose (MC). MCs of various molecular weights were hydrolyzed using two microIMERs containing immobilized celloendoglucanase Cel 5A from Bacillus agaradhaerens (BaCel 5A) connected in series. Hydrolysis by the microIMER could be confirmed from the average molar masses and molar mass distributions measured by size exclusion chromatography (SEC) with online multiangle light scattering and refractive index detection. Methylated cellooligosaccharides with degrees of polymerization (DP) between 1 and 6 formed during hydrolysis were analyzed by direct infusion electrospray ionization ion-trap mass spectrometry (ESI-ITMS). Mass spectra of microIMER- and batch-hydrolyzed samples were compared and no significant differences were found, indicating that microIMER hydrolysis was as efficient as conventional batch hydrolysis. A fast and automated hydrolysis with online MS detection was achieved by connecting the microIMER to high-performance liquid chromatography and ESI-ITMS. This online separation reduced the relative intensities of interfering signals and increased the signal-to-noise ratios in MS. The microIMER hydrolysates were also subjected to SEC interfaced with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. With this technique, oligomers with DP 3-30 could be detected. The hydrolysis by the microIMER was performed within 60 min, i.e. significantly faster compared with batch hydrolysis usually performed for at least 24 h. The microIMER also allowed hydrolysis after 10 days of continuous use. The method presented in this work offers new approaches for the analysis of derivatized cellulose and provides the possibility of convenient online, fast, and more versatile analysis compared with the traditional batch method.