Crack growth predictions using a strip‐yield model for variable‐amplitude and spectrum loading

Fatigue‐crack‐growth tests were conducted on compact, C(T), specimens made of D16Cz aluminum alloy. Constant‐amplitude tests were conducted over a range of stress ratios (R = P_min/P_max = 0.1 to 0.75). Comparisons were made between test data from middle‐crack tension, M(T), specimens from the literature and C(T) specimens. A crack‐closure analysis was used to collapse the rate data from both specimen types into a fairly narrow band over many orders of magnitude in rates using proper constraint factors. Constraint factors were established from single‐spike overload and constant‐amplitude tests. The life‐prediction code, FASTRAN, which is based on the strip‐yield‐model concept, was used to calculate the crack‐length‐against‐cycles under constant‐amplitude (CA) loading and the single‐spike overload (OL) tests; and to predict crack growth under variable‐amplitude (VA) loading on M(T) specimens and simulated aircraft loading spectrum tests on both specimen types. The calculated crack‐growth lives under CA and the OL tests were generally within ±20 % of the test results, the predicted crack‐growth lives for the VA and Mini‐Falstaff tests on the M(T) specimens were short by 30 to 45 %, while the Mini‐Falstaff+ results on the C(T) specimens were within 10 %. Issues on the crack‐starter notch effects under spectrum loading are discussed, and recommendations are suggested on avoiding these notch effects.     

Addressees of performance goals.

As performance goals aim to both procure acknowledgment of one's abilities and to avoid revealing a lack of one's abilities, the authors hypothesized that students hold specific performance goals for different addressees and that there are specific correlational patterns with other motivational constructs. They analyzed a data set of 2,675 pupils (1,248 boys and 1,426 girls) attending Grades 8 and 9 (mean age=15.0, SD=0.97). The students completed a questionnaire consisting of 12 items measuring performance approach goals and 12 items measuring performance avoidance goals. In each subset, 4 groups of addressees were differentiated: parents, teachers, peers, and the acting individual him/herself. Additionally, several external criteria were measured. The authors concurrently tested theory-driven, structural equation models. Incorporating all 24 items, the best-fitting model was a multitrait-multimethod model, which posited 2 factors for approach and avoidance goals and 4 addressee factors. While performance goals addressing parents showed relationships to maladaptive motivational and learning patterns, performance goals addressing classmates and self showed relationships to adaptive motivational and learning patterns. The relationships between performance goals addressing teachers and external criteria were rather weak and unsystematic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

SDS electrophoresis of legume seed proteins in horizontal ultrathin-layer pore gradient gels

Summary Horizontal SDS electrophoresis of 18 legume seed protein extracts was performed in ultrathin-layer polyacrylamide gels on foil supports. Separation results of the SD S pore gradient electrophoresis (T=4–22.5%) are compared to those of SDS electrophoresis in a constant pore size gel (T=10%). Resolution as well as the sensitivity (0.1 g protein per band) of the ultrathin-layer SDS pore-gradient electrophoresis were extremely high. Because of the very low gel thickness, separation, staining and drying were completed in substantially shorter times than achieved with conventional thick gels. An easy technique for casting ultrathin-layer (360 gm) concave gradient gels for 10 cm separation distance and a width of 25 cm is described. The even distribution of the concave exponential pore-gradient over the whole gel width is demonstrated. Molecular weights of the legume proteins are detected from 5,000 to 110,000 daltons. The protein patterns are genus- and species-specific.

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Horizontale Ultradünnschicht SDS-Gradientengel-Elektrophorese von Leguminosensamenproteinen

Zusammenfassung Die ausgezeichnete Trennschärfe der horizontalen Ultradünnschicht-SDS-Gradienten-gel Elektrophorese wird am Beispiel von Samenproteinen 18 verschiedener Leguminosengattungen, -arten und -sorten gezeigt. Es werden die Trennergebnisse der SDS-Elektrophorese mit Gelgradienten (T=4-22,5%) bzw. mit Gelen konstanter Porengröße (T=10%) verglichen. Das höchste Auslösungsvermögen und die beste Trennschärfe zeigen ultradünne Gradientengele. Die Nachweisempfindlichkeit ist bei allen Ultradünn-schicht-SDS-Elektrophoresen sehr hoch (0,1 g Protein/Bande). Da die auf Folie polymerisierten Gele sehr dünn sind (360 m) kann mit wesentlich verkürzten Trenn-, Färbe-, Entfärbe- und Trocknungszeiten gear-beitet werden. Es wird eine einfache Herstellung ultradünner Polyacrylamidgele mit exponentiellen konkaven Gradienten für die Trenndistanz von 10 cm mit einer Breite von 25 cm beschrieben. Die gerade und gleichmäßige Verteilung des Gradienten über die gesamte Gelbreite wird gezeigt. Mit der beschriebenen Methode werden bei den untersuchten Leguminosen-proteinen Molekulargewichte von 5 000 his 110 000 Dalton gefunden. Die Proteinmuster erweisen sich als gattungs- und artspezifisch.

     

Analysis and prevention of corrosion in To chopper systems

T_o neutron choppers at Oak Ridge National Laboratory's Spallation Neutron Source will stop prompt pulses of high-energy neutrons outside the target moderator. Choppers are cooled internally by recirculated distilled water maintained at 15 °C. Numerous metallic components are used to fabricate the choppers and cooling system; water contacts many of these components, establishing a corrosion cell. T_o chopper system corrosion products were investigated analytically. Results showed elevated concentrations of soluble and precipitated iron and copper in cooling water. A chemical-based corrosion strategy was implemented in a T_o chopper system during mechanical tests not involving system irradiation. Chemical analyses showed that a chemical corrosion inhibitor stopped system corrosion for 6 months after its introduction. Corrosion cessation was beneficial, as mechanical tests were performed without interruption from precipitate wear on mechanical parts, flowmeter blockage, or a decrease in heat transfer capabilities. Aqueous chemical changes occurring in the cooling system upon inhibitor addition are discussed.     

Semiautomatic calibration of robot manipulator for visual inspection task

A semiautomatic procedure to calibrate a robot manipulator for improving positioning accuracy is proposed. An error-correcting transformation is estimated using the point-pairs in the theoretical and actual coordinate frames. The theoretical points are obtained using a 3D model of the inspected part, whereas the actual points are derived with image processing and analytic geometry techniques. The estimation of the error-correcting transformation is based on a leastsquare method. Experimental results are described to illustrate the calibration procedure.     

Theoretical and experimental thermal-hydraulic analysis of a new sodium cooled fast breeder reactor core

This paper presents the experimental and theoretical results of the thermal-hydraulic design of a new fast breeder reactor core concept. The main feature of this concept is the omission of fuel element cans.The hydraulic function of these fuel element cans is substituted by a winding flow path through the radial blanket and a ring chamber without tubes.A computer code based on the quasi-continuum-theory and especially adapted to the features of the new core concept is developed for theoretical investigations. The pressure drop of the rod bundles is specified by a resistance tensor.The experimental investigations are realized in a test facility, where sodium is simulated by water. Pressures and velocities are measured.Theoretical and experimental results show good agreement. The aim of flattening of the coolant outlet temperature distribution can be reached with satisfying accuracy.     

Validity of screening for individuals at risk for type I diabetes by combined analysis of antibodies to recombinant proteins

OBJECTIVE: To determine whether screening for the presence of multiple antibody markers for IDDM is effective at identifying individuals with high risk for disease development. RESEARCH DESIGN AND METHODS: Antibodies to GAD and the tyrosine phosphatase-like protein 1A-2 were determined in sequential serum samples from 44 first-degree relatives of IDDM patients, identified as possessing islet cell antibody (ICA) and/or insulin autoantibody (IAA), who were followed prospectively for IDDM development, ICA, IAA, and antibodies to GAD and 1A-2 were also determined in 93 cases of new-onset nonfamilial IDDM. RESULTS: The presence of two or more antibodies in addition to ICA or IAA conferred high risk (61%) for development of IDDM within 5 years of entry into the study and identified 89% of those who have developed IDDM on current follow-up. None of the relatives positive for ICA or IAA alone, in the absence of other antibody markers, have developed IDDM. Antibodies to islet antigens could both appear and disappear in follow-up samples obtained after entry into the study. The majority (60%) of young (< 16 years), sporadic cases of IDDM had multiple antibodies to islet antigens, but this proportion was lower in older patients (37%). CONCLUSIONS: A screening strategy based on the analysis of antibodies to multiple islet antigens can predict IDDM at high sensitivity and specificity in families, and such a strategy may also be applicable to identify young individuals in the general population with high disease risk. Since appearance of antibodies to different antigens occurs sequentially rather than simultaneously, accurate assessment of diabetes risk based on the presence of multiple antibodies will require follow-up over a number of years after the first evidence of islet autoimmunity.     

群青粒子的微胶囊化及其分形表征

研究了群青粒子微胶囊化及改性的方法，并用表面分形维数对粒子的表面形貌予以量化表征。结果表明：群青粒子的微胶囊化是改善群青不耐酸性的有效途径；群青粒子的Ｄ值在２－３这间，微胶囊化后的粒有面分维大于原样品粒子的表面分维，且微胶囊化粒子的Ｄ值越大，生胶囊化改性效果越明显。