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Crack branching in Homalite-100 sheets of 1/8-in. and 3/8-in. thickness was studied by dynamic photoelasticity. Dynamic stress intensity factors, crack velocities and branching angles were measured and corresponding static stress intensity factors were determined by the method of finite element analysis. Dynamic stress intensity factors which preceded the actual branching reached a peak value of approximately three times the fracture toughness. The dynamic stress intensity factor drops prior to branching and then increases again to the maximum stress intensity factor at which point branching could occur again. Roughness of the fracture surface can be related to large dynamic stress intensity factors and crack velocities prior to branching and also after branching. Average branching angle was 26 deg. The results of this series of tests thus suggest that large dynamic stress intensity factors are necessary but not sufficient to cause crack branching.

Viscoelastic response of intact human cornea subjected to physiological intraocular pressure was determined from local deformations measured by a flying spot micrometer. One eye of a paired specimen was prepressurized at 15 mmHg for at least 8 hr while the other eye was left unpressurized before testing. Test results of five paired eyes showed that, in prepressurized enucleated eyes, the viscoelastic response was insignificant while significant viscoelastic response existed in the nonpressurized eyes. The latter viscoelastic properties were characterized by a five-element linear viscoelastic model and a nonlinear hereditary integral by Fung.

Stress intensity magnification factors for an elliptical crack embedded in a finite thickness plate subjected to tensile and bending loading are estimated by judicious use of analytical results obtained previously. These analytical results involve the stress intensity magnification factors for an embedded elliptical crack approaching the free surface of a semi-infinite solid and pressurized by a constant or by a linearly varying pressure. The resultant stress intensity magnification factors for the elliptical crack in a plate are presented in graphical forms for various crack aspect ratios, eccentricity, and proximity factors.

Crack propagation rate in 7075-T6 tension plates was determined for central cracks initially oriented in 45 degrees, 60 degrees, and 90 degrees, to the width direction of the tension plates which were loaded cyclically. Opening and sliding mode of stress intensity factors, K sub 1 and K sub 2, were determined by the method of direct stiffness for curved cracks generated from these initially slanted cracks. Crack propagation rates, Delta a/Delta N, were then plotted against the maximum opening mode of stress intensity factor, K sub 1, in the presence of sliding mode of stress intensity factor, K sub 2. Comparison between the corresponding crack propagation rate in control specimens without K sub 2 showed that the propagation rate is definitely increased in the presence of K sub 2. (Author)

An approximate stress intensity factor is derived for an embedded elliptical crack in a plate which is subjected to uniaxial tension in the direction perpendicular to the crack surface. The major axis of an eccentrically located elliptical crack is assumed to be parallel with the two plate surfaces. The approximate stress intensity factors on the minor axis of the elliptical crack are then determined as αBσ√a√π where a is a correction factor due to the curvature of the ellipse and 6 is a correction factor due to the eccentricity of the crack in the wall.

In a previous paper, a numerical procedure (the finite element method) was presented for the structural analysis of soft biological structures possessing complex geometry and mechanical properties and undergoing large deformations. This method was used here to model a vas vasorum in an arterial cross-section subjected to physiological and hypertensive mean arterial pressure levels. The deformation of the lumen of the model vas vasorum was determined for two cases: an arteriole and a venule. Estimates of hydraulic resistance and flow rate for these model vasa vasorum were calculated and compared with experimental total flow rates in the vasa vasorum reported in the literature. The results indicate that prolonged abnormally elevated arterial pressure could constrict venules of the vasa vasorum thereby impairing arterial wall tissue nourishment. If no compensatory mechanisms exist, tissue degeneration and/or atherogenesis could occur.

The advantages of the complex variable method are combined with the numerical procedure of collocation for estimating the stress intensity factors in finite, cracked plates subjected to in-plane loadings. In this approach, the complex stress functions for an infinite plate problem are modified to meet the boundary conditions for a finite plate with identical crack configuration. This procedure produces a system of linear equations which can be programmed readily on high-speed computers. The procedure is used to find the elastic stress intensity factor at the crack tip in a centrally notched plate in uniaxial tension. The resulting values are nearly identical to the stress intensity values determined analytically by the theory of elasticity. This numerical procedure should be useful for designers and analysts working in the fields of fracture mechanics and fail-safe concepts.

Practically all echo suppressors presently used in long-distance telephone circuits operate on the principle of cutting off the sending circuit when the receiving speech level is greater than the sending speech level, thereby suppressing echoes. Therefore, they generate a faulty speech problem due to the cutting off of speech in simultaneous talking, thus making speech unnatural. To correct this fault, a blockless echo suppressor which, unlike the usual echo suppressors, generates a signal equivalent to the echo to be canceled, has been developed. In the suppressor, a signa1 equivalent to an echo is produced from the convolution of a received speech signal and an echo-path impulse response which is stored in a memory in advance of the commencement of commercial service. It has been confirmed by subjective evaluation that an echo suppressor of this kind manufactured for trials has better talking quality than any other kind of typical echo suppressors now in service. This is because an echo is effectively suppressed more than 30 dB below the transmitted speech signal, and speech is not cut off in this suppressor.

The solution technique of Mossakovskii And Rybka is used to formulate an approximate solution for axisymmetric problems in fracture mechanics. The procedure is then used to determine the stress intensity factor in a flat toroidal crack subjected to internal pressure. The maximum stress intensity factor exists at the inner edge of flat toroidal crack and therefore the crack will always tend to grow into a penny-shaped crack.

Amphotericin B potentiates the antifungal effects of 5-fluorocytosine and rifampicin, probably by increasing the penetration of these agents through the fungal cytoplasmic membrane.

The internal friction of sintered pellets of compositions from UO 2.00 to UO 2.25 , including the phases UO 2+ x and U 4 O 9− y , was measured by an ultrasonic attenuation method over the temperature range from —196 to + 200 °C. Internal friction maxima were observed at about −145 and +85 °C, when measured at 5 Me/sec. The higher temperature maximum can be analyzed into two peaks, one of which increased with the amount of the U 4 O 9− y phase. This one is associated with the phase transition in U 4 O 9− y and the other is attributed to a reorientation of interstitial oxygen atoms in UO 2+ x . The height of the peak below room temperature was proportional to the amount of U 4 O 9− y , phase. This peak may be due to electronic relaxation in the U 4 O 9− y , phase, induced by dislocation motion.

Kobayashi, George S. (Tulane University, New Orleans, La.), and Lorraine Friedman . Characterization of the pyrogenicity of Candida albicans, Saccharomyces cerevisiae , and Cryptococcus neoformans . J. Bacteriol. 88: 660–666. 1964.—The intravenous injection into rabbits of 10 9 yeast cells of Candida albicans, Saccharomyces cerevisiae , or Cryptococcus neoformans (both slightly and heavily encapsulated forms) induced a febrile response indistinguishable from that elicited by gram-negative bacterial endotoxin. There was a brisk rise in body temperature which began as early as 30 min after injection, peaked once or twice, and then returned to normal after about 10 hr. With viable C. albicans , the febrile response did not return to normal but remained elevated for several days and terminated at death of the animal. Of three extraction procedures employed in attempts to isolate the endotoxin-like pyrogenically active substances from C. albicans , only one, the phenol extraction method, was successful. Pyrogenic substances were more easily extractable from S. cerevisiae , but extracted cells of both species were still highly pyrogenic. It was concluded that the particulate nature of the yeast cell did not contribute to the induction of fever, for latex particles of a similar size were nonpyrogenic. Viable or heat-killed C. albicans , phenol extract of C. albicans , zymosan, and polystyrene latex particles all failed to induce in rabbits increased dermal reactivity to epinephrine.

The direct stiffness method is used to formulate a numerical procedure for solving plane structural problems involving large, time-dependent deformations and nonhomogeneous, time-dependent material properties. The stiffness matrix in polar coordinates is derived for the state of plane strain. The nonlinear structural response is incrementally linearized by considering the deformation process to be linear within small time increments. The developed procedure is compared numerically with a known solution of creep deformations in a thick-walled cylinder subjected to internal pressure loading and elevated temperature.

A facile one-step synthesis of adenine has been achieved by the reaction of formamide with POCl 3 in a sealed tube. A maximum yield reached 43·5% of theory calculated on formamide under optimal conditions. Hydrogen cyanide is not considered a possible intermediate for the formation of adenine because H 14 CN added to the reaction mixture is not incorporated. A speculative mechanism for the reaction is proposed.

The shell-movements of the pearl-oysters were recorded by using a weekly kymograph at the natural habitat in winter. When the water-temperature is below 7°C., the valves are completely closed; in the case of 7°-13°C., usually almost closed though often may be recognized very slight movements; in the case of 13°-15°C., the shell-movements become somewhat vigorously; and above 15°C., always actively. So that, it is presumable that 13°C. is the critical water-temperature for the activity of the animal in winter; and this conclusion agrees with that of our previous paper that pearl-oyster hibernates below 13°C.

diagnostic aids has included the use of antigens prepared by a variety of methods. As described by Smith et al (1948, 1950) these preparations have varied from suspensions of Coccidioides immitis cells to phenol extracts of mycelium and filtrates from cultures grown in several different liquid mediums. The method currently in use for preparing coccidioidins for the 3 immunologic tests employs filtrates from cultures grown in a modified Bureau of Animal Industy tuberculin medium (Smith et al, 1948). The preparation of coccidioidins in this medium usually involves incubation for 8 weeks or more

The mechanics of finishing in a press-forging operation were analyzed. It was concluded that the metal in the die, as well as that contained in the flash, could be treated as a fictitious disk which is subjected to compression between flat surfaces under variable surface friction. Comparison of experimental average pressures with those predicted by the foregoing simplified theory showed good agreement.

The following alloys were investigated in orthogonal metal-cutting tests at varying cutting speeds, rake angles, and feeds: Steel SAE 1112 annealed and as-received; steel SAE 1020 as-received; steel SAE 4135, annealed, as-received, and Rockwell hardnesses 27 and 35–37; aluminum alloy 2024-T4; aluminum alloy 6061 in the 0 and T6 conditions; alpha brass. The new data obtained in the present investigation under wide variation of test conditions (speed for SAE 1112 annealed and as-received was varied from 0.083–1010 fpm) confirmed earlier observations [1, 3] that the shearing stresses are independent of the test conditions investigated. These observations were supported by theoretical considerations. Correlation of metal-cutting data with compression data on the basis of the incremental or distortion-energy theory was good for the ductile metals. Less perfect correlation was observed with SAE steel 4135 and aluminum alloy 2024-T4. It was found further that none of the known theoretical angle relationships were in agreement with all of the experimental data.

The differential cross section for the reaction γp → π 0 p at forward angles has been measured in the energy region between 350 MeV and 1175 MeV. A phenomenological multiple analysis was carried out on the present data together with other data.

Isochromatic patterns associated with dynamic brittle crack propagation were recorded by means of a modified Schardin multiple-spark-gap, dynamic polariscope for 10 × 10 in. Homalite-100 edge crack panels. With the material properties determined by dynamic calibration, the resulting photoelastic information was used to evaluate the elastic fields surrounding the propagating crack by the semi-inverse technique. This solution was characterized by the dynamic stress intensity factor whose behavior was determined for accelerating, constant velocity, and arresting cracks. For the series of experiments discussed and the evaluation procedure used, the local stress field surrounding the dynamic crack can be characterized by a two-parameter stress function model. With this model, it was found that the change in crack velocity lagged the change in the dynamic stress intensity factor, but that the degree of crack surface roughness correlated closely with the magnitude of the stress intensity factor.

The direct stiffness method is used to analyze the structural response of the cross section of an arteriole which is both heterogeneous and nonlinear in terms of structural response. A typical segment of the cross section is represented by an assembly of triangular elements. The stiffness matrix and strain-displacement relationships are then derived in terms of polar coordinates for a triangular plate element. Viscoelasticity is included in this structural analysis by using a piecewise linear approach. Stress-time and displacement-time data are presented for two typical cross sections of the arteriole. These results reveal special properties of a heterogeneous structure which is undergoing viscoelastic deformations.

A 16-spark gap, modified schardin-type camera was constructed for use in dynamic photoelastic analysis of fracturing plastic plates. Using this camera system, dynamic photoelastic patterns in fracturing Homalite-100 plates, 3/8 in. × 10 in. × 15 in. with an effective test area of 10 in. × 10 in., loaded under fixed grip condition were recorded. The loading conditions were adjusted such that crack acceleration, branching, constant velocity, deceleration and arrest were achieved.

The differential cross sections of the γ+ d →π 0 + d reaction have been measured at the pion angle of 50° in the center of mass system and in the photon energy range from 650 MeV to 820 MeV, for the purpose of estimating the isotopic vector part of the photopion production amplitude from nucleons around the second resonance, N 1/2 * (1525). Recoiled deuterons were measured with the combination of the momentum analysis with a magnet and the time of flight measurement. The measured cross section together with data obtained by us in the previous experiment were analysed basing on the impulse approximation. The s 11 -, s 31 -, p 33 -, p 11 - and d 13 -waves are included in the analysis. The results of analysis are consistent with the conclusion that the isotopic vector part is dominant in the d 13 -wave amplitude of π 0 photoproduction from free nucleons around the N 1/2 * (1525) resonance.

Observation of swallowing movement was done using X-ray TV in 160 patients including 14 cases of the malignancy in the hypopharynx and the esophagus and following results were obtained. 1. There js a possibility that the so-called “foreign body sensation” could be the initial symptom of the malignancy in this region. 2. X ray examination, as first choice and then endoscopy if necessary as a result of X ray examination should be done in such patients as a routine examination. 3. Pharyngeal stasis was very frequently observed in the malignancy in this region.

In order to compare the size and pattern of craniofacial complex among irus monkeys from different habitats to each other, roentgenographic cephalometric measurement on seven items for linear measurement and ten items for angular measurement were carried out on dry skulls of eighty-six irus monkeys from Malaya, the Philippines, Thailand and Vietnam. In the groups from Malaya and the Philippines, the mean values of linear measurement are larger in male than in female, and differences are especially significant in the distances between the gonion and infradentale, posterior nasal spine and prosthion, and nasion and incision. In the angular measurement, the difference between sexes is significant in the mandibular plane angle, occlusal plane angle, lower central incisor to occlusal plane angle, lower central incisor to mandibular plane angle and Frankfort horizontal plane to sella-nasion angle. In male, the Philippine group is larger than the Malayan in the size of cranium, but there is no significant difference in pattern. In female, the Malayan group is the smallest in these four groups and the size of the cranium of the Thailander and Vietnamese, as well as the pattern of craniofacial complex, are most similar to each other. As compared with the human cranium, the facial pattern of irus monkeys is characterized by a strong inclination of the cranial base, small values of the gonial angle and foreward inclination of anterior teeth.

Pappagianis , D. (University of California, Berkeley), E. W. Putman, and G. S. Kobayashi . Polysaccharide of Coccidioides immitis . J. Bacteriol. 82: 714–723. 1961.—Soluble polysaccharide from mycelia or culture filtrates of Coccidioides immitis was found to consist mainly of mannose, but also included small quantities of galactose and another reducing sugar. Isolation of the polysaccharide by ethanol precipitation provided accompanying nitrogenous material. There was 3 to 4% nitrogen, present in amino acids, but in a nondialyzable (possibly protein or peptide) form. The average molecular weight of the complex was 31,700. Attempts to separate the nitrogenous and polysaccharide materials by chemical methods or by moving boundary electrophoresis were unsuccessful; ultracentrifugation showed a single peak. Despite these findings, there appeared to be several antigenic species present, as indicated by multiple lines of precipitation in double diffusion and quantitative precipitin tests. In the latter, polysaccharide-containing fractions gave precipitates without measurable carbohydrate, suggesting separability of nitrogenous and polysaccharide components.

Amphotericin B was found to potentiate the antifungal effects of mycophenolic acid glucuronide, tetracycline, and actinomycin D by increasing the penetration of these antibiotics through the fungal cytoplasmic membrane. Because the fungi were over 100 times more susceptible than animal cells to these effects of amphotericin B, these observations might have clinical application.