A comparative study of fatigue properties of two face-centered-cubic metals

Fatigue tests were performed on two sets of specimens made of aluminum and nickel. The cyclic stress strain curve (CSSC) of aluminum exhibited a cyclic hardening response, in which the saturation stress increased with plastic strain amplitude, whereas the CSSC of nickel exhibited cyclic hardening in two stages: a stage at which saturation stress increases with plastic strain amplitudes and a second stage, which exhibits a semiplateau showing a slight increase in saturation stress with plastic strain amplitudes. Transmission electron microscopy (TEM) analysis of both materials showed that nickel contains elongated dislocations and persistent slip bands, while aluminum contains dislocation cells. This article is based on a presentation made in the symposium entitled “Fourth International Alloy Conference”, which occurred in Kos, Greece, from June 26 to July 1, 2005, and was sponsored by Engineering Conferences International (ECI) and co-sponsored by Lawrence Livermore National Laboratory and Naval Research Laboratory, United Kingdom.     

Standard linear plans in single channel high dose rate brachytherapy: a dosimetric analysis

Highly purified recombinant gag and env proteins derived from Icelandic strain 1514 of maedi-visna virus were used in an indirect enzyme immunoassay (ELISA) to detect antibodies to small ruminant lentiviruses in sheep and goat sera. The recombinant protein-based ELISA performed very well relative to whole maedi-visna virus and whole caprine arthritis-encephalitis-virus-based ELISAs in its ability to detect anti-maedi visna virus and anti-caprine arthritis-encephalitis virus antibodies, despite the antigenic and genomic variability that is known to exist within and between these two small ruminant lentiviruses. The data suggest that these recombinant maedi-visna virus proteins can be reliably used in an ELISA for the routine serodiagnosis of lentiviral infections in sheep and goats.     

Influence of timing on the dosimetric analysis of transperineal ultrasound-guided, prostatic conformal brachytherapy

Postoperative computed tomography (CT)-based dosimetric analysis of transperineal ultrasound-guided conformal prostate brachytherapy provides detailed information regarding the coverage and uniformity of the implant. However, there is no generally accepted standard for the optimal timing of the postoperative dosimetry. This report details dosimetric analysis and the effect of timing based upon CT and orthogonal film evaluation for ten unselected patients implanted with either iodine-125 (125I) or palladium-103 (103Pd). Within 2 hours after implantation, patients underwent a CT scan and the first of four sequential sets of orthogonal films. Subsequent orthogonal films were obtained on days 3, 14, and 28 postimplant. CT-based dosimetry revealed coverage of the prostate to the prescribed minimal peripheral dose (mPD) at 93.1 +/- 3.6% of the volume, the prostate volume receiving 150% of mPD was 38.2 +/- 8.7%, and the urethral and rectal doses were 114 +/- 12% and 78 +/- 19% of mPD, respectively. The implanted seeds seen on orthogonal films acted as markers for temporal changes in prostate dimensions, and the standard deviation of each dimension was used as input in an ellipsoidal volume calculation. Seed coordinates were self normalized to the center of gravity of each two-dimensional view and were measured relative to the linear regression line in the superior-inferior direction. The reproducibility of the anteroposterior (AP) film setup in terms of temporal variation in the angle of the regression line was markedly better than that of the lateral films, 1.8 degrees +/- 1.2 degrees vs. 4.3 degrees +/- 2.6 degrees, respectively. Dimensional contraction from day 0 to day 28 averaged 11.3% in the superior-inferior direction, 8.5% in the AP/PA (posteroanterior) direction, and 2.5% in the right-left lateral direction. This translated into a volume change of 20.9% (ranged 11.6-31.6%), which was determined by using the ellipsoid method. The half-life for edema resolution was 10.6 +/- 1.8 days (range 8.6-14.3 days). However, because of variability in the degree and extent of edema and its rate of resolution, we believe that it may be futile to define a single point in time as the most accurate indicator of the postoperative dose distribution. Rather, it may be preferable to accept universal standardization of timing and methodology for CT-based postoperative dosimetry, which would facilitate comparison of results between centers and maximize the information content of that single measurement. We conclude that day 0 represents the optimal time, because dosimetric evaluation at that time minimizes patient discomfort and inconvenience (a catheter is already in place), provides information about edema when it is near its maximum extent, and provides prompt closure of the learning loop and, as such, hopefully will result in improved implantation techniques and results.     

Biochemical properties of amylase isozymes from Gammarus palustris. A comparative study

Two major alpha-amylase isozymes from Gammarus palustris were purified and characterized. These isozymes, Amy IW and Amy Ic, exhibit a seasonal pattern of expression. In this article we investigate whether the seasonal variation has an adaptive significance. In addition, the species-specific properties of amylases were studied. Purification of the isozymes was achieved by sequential glycogen-ethanol precipitation, Sephadex G-200 and ion exchange chromatography. Characterization in terms of Km, activity patterns at different temperatures, pH values and salt concentrations was done for both isozymes. In addition, the distribution of enzymatic products was analyzed in a high-performance liquid chromatography system. In all conditions tested, the two isozymes gave similar results. This observation suggests that the seasonal change in amylase expression pattern does not result in enzymes differentially suited for seasonal variation in conditions. A comparative analysis showed that G. palustris amylases are apparently distinct from other amylases. These distinctions were seen as an unusually low Km value, an activity peak at low NaCl concentration, a relatively high pH optimum and the predominant formation of maltotriose.     

A comparative study on physicochemical properties of hydroxyapatite powders derived from natural and synthetic sources

Hydroxy apatite (HA) is effectively used as a bioimplant material because it closely resembles bone apatite and exhibits good biocompatibility. So, in this research, HA powders were produced by calcinations of natural bones including human, bovine, camel and horse bones, and also via sol-gel method. Powders characterizations of natural HA and Synthetic HA were studied by X-ray powder diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM), combined with transmission electron microscopy (ТЕМ). In order to verify the biocompatibility of these HA powders, MTT assay was applied. The XRD results showed that the HA powders were successfully produced by using different sources. Also, it was obvious from XRF analysis that the main components of them were Ca and P. Furthermore, it was seen that the size of particles was in the nanometric scale and they showed agglomerates consisting of numerous nanocrystals. FTIR spectra of all samples proved the presence of various CO ₃ ^2- , PO ₄ ^3- and OH^– groups in the powders. In addition, the MTT assay revealed that the cells proliferations in the presence of horse and human HA nanopowders were stimulated.     

Simplified method for three-dimensional evaluation of interstitial brachytherapy applications

Although three-dimensional (3-D) treatment planning has primarily been used for external beam radiation therapy, the advantages of 3-D treatment planning can be realized for brachytherapy applications. As with teletherapy, the use of 3-D treatment planning for brachytherapy can provide both superior dose distribution as well as detailed evaluations of the relationship of dose and volume in critical structures and target tissues. Conventional 3-D treatment planning uses computed tomography (CT) scans to localize structures; however, localizing individual brachytherapy sources on each CT slice can be impractical for routine clinical use. In the transition from two-dimensional to 3-D localization and dose evaluation of interstitial perineal templates in particular, a practical method of seed localization on a postimplant CT dataset has been developed. This method does not utilize dummy sources and, as such, does not require individual seed locations to be identified. Instead, the position of the afterloading catheter is defined as a reference line by connecting its location as seen on the axial CT slices and seed locations defined along its length. Full volumetric calculations can then be performed, including dose-volume histograms (DVH) for critical organs and tumor volumes. Source localization and normal tissue doses were calculated using both orthogonal films and the 3-D method for a series of perineal template guided implants. Point dose calculations of the rectum and bladder were obtained from orthogonal films and were then compared to the corresponding DVHs for these organs.     

Plastic properties of pitch-coke compositions

The results of investigating the rheological behavior of pitch-coke compositions containing 55% pitch and coke dust of various granulometric compositions with a particle size smaller than 0.212 mm are presented. It is shown that, at temperatures simulating the production parameters of the anode mass (433–493 K), the pitch-coke compositions can be characterized as the Bingham systems. It is revealed that their rheological properties are affected by the dispersity of the solid phase, content of the coke charge, and temperature. Quantitative characteristics of the flow are found, namely, the yield point, plastic viscosity, and apparent activation energy of the flow.     

A comparative study on mechanical properties of ultrafine-grained Al 6061 and Al 6063 alloys processed by cryorolling

The present work has been focused to investigate the mechanical behavior and microstructural characteristics of cryorolled Al 6063 and Al 6061 alloys. Hardness and tensile tests of the cryorolled Al alloys were carried out to understand its deformation behavior. SEM/EBSD was used to characterise the microstructures of cryorolled Al alloys and observed the formation of ultrafine-grained microstructures in the materials due to severe plastic strain induced during cryorolling. XRD was used to analyse the formation of different phases during cryorolling of the Al alloys. It is evident from the present study that UFG Al alloys exhibit higher hardness and strength when compared to the bulk Al alloys due to the grain size, higher dislocation density and precipitation hardening effect. The cryorolled Al 6061 alloys exhibit higher tensile strength (346 MPa) and hardness (120 H_v) as compared to Al 6063 alloys (Tensile strength: 240MPa and Hardness: 96.5 H_v) in the present investigation. The deformation mechanisms of UFG Al alloys contributing to their enhanced strength are discussed.     

Sandplay: A comparative study.

Examined differences in play themes, play characteristics, object use, and narratives, elicited by the sandplay technique, with 5 coping (CG) and 5 difficulty-coping (DCG) 6–8 yr olds. Differences between the 2 groups, and the assessment and therapeutic value of sandplay was ascertained. Sandplay was adapted from the work of M. Lowenfield (1979), who in 1929 developed the technique of using miniature figures in a sand tray to encourage children to create a symbolic representation of their world in concrete form. Ss participated individually in sandplay, on 4 separate occasions, and over a 2 mo period. The CG tended to view their world as more balanced, vital, and organized, where others guide them, and they are safe. They showed resourcefulness in dealing with adversity and had hope for the future. The DCG tended to perceive their world as barren, a struggle, and consisting of threat and danger. The tended to lack resourcefulness in dealing with adversity and had a lack of hope for the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparative study of NdY-Fe-B magnet and NdCe-Fe-B magnet

Low cost and high abundance rare earth elements Y and Ce have attracted tremendous interests of the industrial and scientific societies for fabricating the highly cost-performance efficient rare earth permanent magnets. However, the effect of separate replacement of Nd by Y or Ce on the performances of NdFeB-type magnet under the same atomic ratio and preparation conditions is still unclear. In this work, we systematically investigated the magnetic properties, thermal stabilities and service performances of (Nd_0.8Y_0.2)_13.80Fe_balAl_0.24Cu_0.1B_6.04 (atomic fraction, denoted as 20Y) and (Nd_0.8Ce_0.2)_13.80Fe_balAl_0.24Cu_0.1B_6.04 (atomic fraction, denoted as 20Ce) magnets. The results demonstrate that the μ₀M_r, μ₀H_c and (BH)_max of 20Y magnet are respectively 1.325 T, 1.173 T and 343.467 kJ/m³, which are comprehensively higher than those of 20Ce magnet (μ₀M_r = 1.310 T, μ₀H_c = 0.948 T, (BH)_max = 321.105 kJ/m³). Moreover, the 20Y magnet has higher thermal stability compared with 20Ce magnet which is favorable for the magnetic performances at elevated temperatures. The investigation of microstructure and elemental distribution indicates that the excellent magnetic performances of NdY-Fe-B magnet can be attributed not only to the preferable intrinsic properties 4πM_s, H_a and T_c of Y₂Fe₁₄B, but also to the in-situ core–shell structure of the 2:14:1 matrix phase grain with Y-rich core and Nd-rich shell, along with the thicker grain boundary layer between the adjacent matrix phase grains in NdY-Fe-B magnet. Furthermore, the 20Y magnet exhibits better mechanical property and higher corrosion resistance than 20Ce magnet, which are helpful for prolonging the service life of the magnet in practical application.     

A comparative study of dynamic and static testing in abstinent alcoholics

The performance of 44 Finnish alcoholics was measured on a Vygotskian version of the Raven's Progressive Matrices and four traditional static tests (the Digit Symbol and Block Design subtests from the WAIS, Part B of the Trial Making Test, and the Embedded Figures Test). Of the static tests only the Block Design showed consistent congruence with the results of the learning potential test. The other static tests discriminated only partially from each other the groups which were formed according to learning potential. The most fruitful way to test alcoholics is probably to have a flexible combination of static and dynamic tests. We also need to have tests that are applicable to both static and dynamic testing.     

A comparative study of interval and conventional training in thoroughbred racehorses

Eight horses with previous racing experience were used in a comparative study of training methods for Thoroughbred racehorses. They were randomly assigned to two groups of four horses each. One group was trained using an interval training method (IT) and the other using conventional training (CT) methods. Peak heart rates, heart rate recovery curves, peak plasma lactate levels, plasma lactate clearance rates and run times were used to evaluate differences in the training methods. Peak heart rates, heart rate recovery curves, and run times were not significantly different between the groups. However, higher lactate production and increased plasma lactate clearance by the IT group demonstrated an increased anaerobic capacity.     

A comparative study of death anxiety in hospice and emergency nurses

This paper describes a preliminary cross-sectional study which aimed to compare levels of death anxiety and coping responses in palliative care and accident and emergency (A & E) nurses. Forty-three nurses (23 from palliative care and 20 from A & E) were recruited from a district general hospital and nearby hospice. Both sites had the same mean annual death rate of 150 patients. Death anxiety was measured by the Death Attitude Profile-Revised Questionnaire and coping responses were elicited by a semi-structured interview. As hypothesized, hospice nurses had lower death anxiety and they were more likely to recall both good and difficult experiences related to patient care. Unlike the hospice nurses, a subgroup (20%) of A & E nurses reported that they were unable to discuss problems with colleagues. The study has implications for the development of institutional support for staff to enable nurses to provide good quality care for dying patients and bereaved people.     

Plastic properties of homogenized coke-pitch compositions

The rheological properties of coke-pitch compositions are investigated after their mechanical activation (MA) treatment in the hydroblow-cavitation field for three compositions of a coke charge containing finely dispersed coke fractions. The rheological properties of these mixtures are compared with those not subjected to MA. It is established that, as a result of MA, plastic viscosity decreases. As the temperature increases, this quantity initially decreases and then becomes almost constant. The apparent activation energy of the viscous flow increases as the content of finely dispersed coke fraction increases and has the same order of magnitudes for compositions before and after MA.     

A comparative study of programed and conventional instruction in industry.

"Programed textbooks containing 719 frames were prepared covering the introductory 15 hours of a 16-week course for trainees in a 7070 Data Processing System servicing course. Achievement test scores for six experimental classes (n = 70) who used these programed texts were compared with those of two control classes (n = 42) taught by the lecture-discussion method. Significant gains in achievement and reduction of training time were found for the experimental classes. Student reaction to programed instruction as measured by a questionnaire was found to be favorable." From Psyc Abstracts 36:04:4KC25H. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

常用塑料给水管材技术经济比较

简要简绍塑料给水管替代镀锌钢管的因素,对常用塑料给水管材作了较详细的介绍,并就其物理化学性能、工程技术性能、经济性能进行了充分的阐述、比较。     

A comparative study of anxiogenic effects of fluoroquinolones in rats

It is well known that the removal of a fixation point prior to the presentation of a peripheral target dramatically reduces saccadic reaction time (SRT). This effect has become known as the "gap effect". The present study examined several detailed kinematic variables to determine whether the removal of the fixation point also affects the manner in which saccades are produced. The findings indicate that saccades that were initiated after the removal of the fixation point had higher average velocities and reached greater peak velocities, accelerations, and decelerations than did saccades produced in the presence of the fixation point. The results suggest that the removal of the fixation point may affect the force-time curves of saccades in addition to affecting the time needed to initiate the saccades.