Untersuchungen zur Anwendung der Bruchmechanik auf duktile Werkstoffe am Beispiel des Bruchverhaltens von weichmacherfreiem Polyvinylchlorid

Study on the Application of the Fracture Mechanics Concept to Ductile Materials–Fracture Behavior of Rigid PVC The fracture behavior of ductile materials cannot be treated by the methods of linear elastic fracture mechanics concept. For these materials the application of extended theories, which consider the non-linear stress-strain-relationship, is necessary. The test results being reported here have been obtained from rigid blue colored PVC. CT-specimens of different sizes were tested in tension at different loading rates. Above a certain strain level, the material shows crazing. This makes it possible to determine the plastic zone size. The relatively low Young's modulus originates in great deformations of the specimen. The deformation can therefore be measured with great accuracy. During the tests, a great number of quantities were registered. From these quantities the stress intensity factor, crack opening displacement, I-Integral and so on were calculated. The applicability of the results, in order to describe the fracture behavior of ductile materials, is being discussed.     

Harry Goichi Yamaguchi (1921-2002).

Reports the death of Harry Goichi Yamaguchi (1921-2002) and notes his contributions to to teaching, research, and clinical supervision and research. In keeping with his clinical experience with children and adolescents, Yamaguchi emphasized developmental psychology in his teaching. Learning theory remained the focus in his research, his publication, and his approach to clinical work. Yamaguchi's work with several professional organizations is also noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis of poly(N,N-dimethylaminopropylacryl amide-g-acrylic acid) and crosslinking of its trunk sequence

Summary The graft copolymers composed of weak base and weak acid sequences, i.e., poly(N,N-dimethylaminopropylacryl amide-g-acrylic acid) (poly(DAPA-AA)) including 51–87 mol% of acrylic acid (AA) were prepared by redox system using cerium(IV) ammonium sulfate as initiator. Microphase separation of two sequences was observed in basic casting solvent. The crosslinking of DAPA sequence, which had shown spheric morphology, was carried out by mean of gas-solid phase quaternization reaction with 1,4-dibromobutane. The reaction product was soluble in NaOH aq. or HCl aq. until 4.3% quaternization of DAPA unit without remarkable increase of intrinsic viscosity. And they were found to be very different in solubility from the raw graft copolymer.     

Cooperation of phosphatidylcholine with endogenous lipids of wheat flour for an increase in dough volume

Phosphatidylcholine (PC) increases the gas-retaining ability of dough, the dough volume on fermentation and the loaf volume of bread. The cooperation of wheat flour endogenous lipids with PC was examined. More than 90% of the total wheat flour lipids were extracted with chloroform, the extracted lipids comprising glycolipids (33 wt%), non-polar lipids (56 wt%), and phospholipids (11 wt%). The increase in the specific volume of dough with delipidated wheat flour by the addition of PC was smaller than the increase in the specific volume of dough with native wheat flour. The addition of the extracted lipids to delipidated wheat flour restored the increase in dough volume by the addition of PC. The glycolipid fraction of the extracted lipids was most effective for enhancing the action of PC. The results suggest that interaction of PC with wheat flour glycolipids may synergistically increase foam stability to enhance the gas-retaining stability of dough.     

Engineering Freshman Enrollments: Critical and Non-critical Factors

Freshman enrollment and bachelors degree data over the last three decades for all undergraduates as well as engineering students are analyzed and compared to variations in the numbers of high school graduates. Engineering enrollment data trends are shown to differ significantly from those of undergraduates as a whole and to exhibit little correlation with trends in high school graduation data. Freshman engineering enrollments show a very strong correlation with factors which might indicate to high school students the magnitude of their personal economic gain such as on-campus industrial interviewing intensity, annual growth in starting salaries and starting salary levels relative to average salaries of all undergraduates. No correlation between engineering freshman enrollments and national economic conditions as measured by the Gross Domestic Product or unemployment was found. Implications of the correlation between freshman enrollments and perceived personal economic reward are considered in terms of strategies for recruiting freshmen, student performance in engineering curricula and trends for the future.     

The screening and referral of mentally disordered inmates in a state correctional system.

A process of shaping untrained personnel to make appropriate psychiatric referrals in a state correctional system is explained. The application of this process in the South Carolina Department of Corrections was evaluated by determining the percentage of appropriate referrals made by these untrained personnel (e.g., nurses, wardens, chaplains, psychometricians). All referrals made during March 1978 served as a sample of the effectiveness of the system. The personnel who made the referrals were interviewed with respect to both the specific referral(s) and the general decision rules employed in making the referrals to the psychiatric unit. Results indicate that the untrained personnel who had been shaped by the director of the psychiatric unit made a high percentage of appropriate referrals than those who had not been shaped. Other uses of this shaping procedure as well as the apparent lack of need for more highly trained personnel are discussed. (1 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measurement of the Parity-Violating Neutron Spin Rotation in 4He

In the meson exchange model of weak nucleon-nucleon (NN) interactions, the exchange of virtual mesons between the nucleons is parameterized by a set of weak meson exchange amplitudes. The strengths of these amplitudes from theoretical calculations are not well known, and experimental measurements of parity-violating (PV) observables in different nuclear systems have not constrained their values. Transversely polarized cold neutrons traveling through liquid helium experience a PV spin rotation due to the weak interaction with an angle proportional to a linear combination of these weak meson exchange amplitudes. A measurement of the PV neutron spin rotation in helium (φ_PV (n,α)) would provide information about the relative strengths of the weak meson exchange amplitudes, and with the longitudinal analyzing power measurement in the p + α system, allow the first comparison between isospin mirror systems in weak NN interaction. An earlier experiment performed at NIST obtained a result consistent with zero: φ_PV (n,α) = (8.0 ±14(stat) ±2.2(syst)) ×10⁻⁷ rad / m[1]. We describe a modified apparatus using a superfluid helium target to increase statistics and reduce systematic effects in an effort to reach a sensitivity goal of 10⁻⁷ rad/m.     

Übertragung von Schwingfestigkeitswerten mit dem statistischen Größeneinfluß

Transfer of Fatigue Life Data with the Statistical Size Effect The statistical size effect and the Basquin-equation are used to derive a function with the ability to describe the failure probability of fatigue data. Based on the results of fatigue tests the transfer of the life times to other specimens is possible. The specimens may differ in their shape and size. The assumptions, limitations and the potential of the proposed method are discussed and proved in a large experimental programme. Six specimen geometries where made of the Al-alloy 7075 T 7351 and loaded with two different load histories (Gauss, MiniTWIST). The highly stressed part of the specimens, where the cracks will originate, is characterized with stress integral. The location of the initial cracks is examined and correlated with the local stress, which is responsible for crack initiation.     

The tensile fatigue behavior of CT-specimens with small notch root radius

Fatigue tests with sharply notched compact tension (CT) specimens of 7075-T6 aluminum were conducted for constant ratios of R=σ _min/σ _max and constant notch root radius, ρ. By monitoring the crack propagation throughout the tests, the number of cycles at which the characteristic state of stress near the notch root has no further influence on crack tip velocity could be determined. The results are discussed on the basis of Neuber's theory of macro-support effect. An analogy to linear elastic fracture mechanics is pointed out.     

(S)-2,3-Dihydrofarnesoic Acid, a New Component in Cephalic Glands of Male European Beewolves Philanthus triangulum

The chemical composition and functional significance of pheromones of solitary Hymenoptera is much less well known compared to social species. Males of the genus Philanthus (Sphecidae) are territorial and scent mark their territories to attract females. Because of inconsistent results of earlier studies, we reanalyzed the content of the cephalic glands of male European beewolves, Philanthus triangulum F. Besides a variety of alkanes and alkenes, four major compounds were found. Two of these, (Z)-11-eicosen-1-ol and (Z)-10-nonadecen-2-one, had been previously described as constituents of the cephalic glands. We identified 1-octadecanol as a new component of the cephalic gland, and a fourth compound, enantiopure (S)-2,3-dihydrofarnesoic acid, was identified for the first time in nature. Structural elucidation and enantiomeric analysis were performed by HRGC-MS and HRGC-FTIR as well as enantioselective gas chromatography and by means of authentic reference compounds. Occurrence and