bluuebunny/crossref_metadata_2025_split huggingface dataset:
Edge Stresses in a Composite Strip Subjected to Axial Temperature Gradients, Part I: Development of the Theoretical Solution
Authors: Swett Dwight W. , Shiflett Geoffrey R. 
Published: April 2011

In Part I of this paper, a combination of Airy stress functions and direct displacement functions is utilized to obtain the plane elasticity solution for the stresses and displacements in a multilayer laminated anisotropic strip subjected to a temperature gradient that is arbitrarily symmetric in the longitudinal direction. The method of analysis utilized departs from previous works in that an eigenfunction solution is developed assuming a length coordinate expansion of the stresses and displacements, with an exponential variation in the thickness coordinate direction. This avoids the shortcoming of the nonorthogonal Fadle-Papkovitsch eigenfunctions in that an orthogonal series repesentation suitable for modeling of nonuniform as well as uniform temperature distributions is obtained. The resulting eigenfunctions satisfy the necessary equations of equilibrium, conditions of displacement compatibility, requirements on interlaminar stress and displacement continuity, traction free surface conditions, and shear traction free edge conditions. As interfacial conditions and strain compatibility are satisfied exactly, the approach overcomes the inter-facial approximations and average sense compatibility invoked in previous complementary virtual work approaches. The solution does not exactly satisfy the free edge normal traction requirement since only resultant force is enforced to zero; however, convergence for enforced zero transverse slope at the strip ends can be established, as the eigenfunctionsare orthogonal. Thus the solution is exact for these edge conditions. In Part II of this paper, numerical results are presented for several examples and compared to those obtained from our own MSC/NASTRAN finite element analyses. The results indicate the shear and peel stress concentrations and axial stress distributions are in excellent agreement with the finite element analyses for the zero edge slope boundary condition. Also, good correlation was determined with finite element analysis results for the free edge boundary condition over the range of problems considered. This correlation with the finite element numerical results verifies the solution and indicates application of the solution as an approximation to free edge engineering problems is reasonable for abroad range of practical cases.
Aspects of the Failure and Postfailure of Fiber Composites in Compression
Authors: Kyriakides S. , Ruff A. E. 
Published: April 2011

In this paper the analysis of the compressive failure of an AS4/PEEK composite started in [10] is continued. The compressive strength of this material is typically 60% of its tensile strength. It has been long suspected that this is related to fiber misalignment. Two types of fiber imperfections were found in the material analyzed: imperfections introduced during the manufacturing of the prepreg, and fiber waviness introduced during the lamination and final curing of the composite. Failure due to uniaxial compression takes the form of kink bands of distinct widths and inclinations. Kink bands were preserved by conducting the experiments on circular cross section cylindrical rods which were radially confined. Post-failure examination of the kink bands showed them to be at angles ranging from 11°-16° to the x2 direction of the material. Furthermore, all kink planes were found to have normals in the two orthogonal planes containing the imperfections. The problem was idealized as a two-dimensional solid with alternating layers of matrix and fibers. The models account for material and geometric nonlinearities and the two types of fiber imperfections seen in this composite. The response is characterized by a load maximum which represents the strength of the material. The strength is strongly influenced by the imperfection wavelength, amplitude and spatial distribution. The load maximum is followed by fiber bending confined to narrow inclined zones. The fibers eventually break into distinct kink bands because of excessive bending. The inclinations and widths of the highly deformed zones just before fiber breaking is expected to start were found to be similar to those of the kink bands measured in the experiments.
Design of Composite Laminates for Strength, Weight, and Manufacturability
Authors: Fine Andrew S. , Springer George S. 
Published: April 2011

A procedure is presented for determining the layups of unidirectional fiber reinforced composite plates (with or without cutouts) subjected to multiple in-plane and out-of-plane loadsets, such that the plate satisfies the Tsai-Wu Quadratic Strength Failure criterion, is of low weight, and has a layup which is easy to manufacture. Additionally, the desired cure cycle is generated for thermosetting matrix composite plates such that during cure the maximum allowed temperature is not exceeded, after cure the plate is fully cured and fully compacted, and the cure is achieved in the shortest time. The design of the layup for strength and weight (utilizing a finite element method for the stress analysis) is based on the Hybrid Algorithm for Laminate Optimization, modified to result in plates in which preassigned regions are of uniform thickness. The design of the layup for ease of manufacture is based on rules. The cure cycle is determined by simulating the cure process of the thermosetting matrix with a deterministic model "controlled" interactively by an expert system. A computer code SMARTOPT was developed which combines all the above features of the design process and, for specified geometry, material properties, and applied loadsets, provides the desired layup and cure cycle. Results for sample problems were generated which demonstrate the usefulness of the computer code for designing composite plates. The results also show that with proper design, plates made of composite materials can be made lighter than plates made of metals.
The Effect of Cooling Rate on Free-Edge Stress Development in Semi-Crystalline Thermoplastic Laminates
Authors: Domb Moshe M. , Hansen Jorn S. 
Published: April 2011

A numerical model is developed for prediction of the process-induced thermal residual stresses in thermoplastic composite laminates. The model addresses the development of the three-dimensional residual stress state in fracture-critical free-edge regions as well as through-thickness stress variations. The current approach and analysis provide a unique capability for the investigation of the influence of thermal processing and structural parameters on the resulting buildup of residual stresses during manufacturing. Therefore, it can assist in the design and analysis of thermoplastic composites in terms of tailoring of mechanical and strength characteristics. The applied surface cooling rate from the melt has a strong effect on the free-edge stress levels obtained at room temperature, and in particular the interlaminar stresses. Results are shown for the case of typical cross-ply and quasi-isotropic APC-2 (graphite/polyether-ether-ketone) laminates.
Design Optimization of Composite Plates: Part II—Structural Optimization by Plydrop Tapering
Authors: Manne Philippe M. , Tsai Stephen W. 
Published: April 2011

A preliminary design tool was developed to optimize structures such as beams and plates, with optional cutouts, subject to multiple loadsets and any boundary conditions. SUNSPOT provides with simple, tapered and manufacturable layups. Sublaminates, made of multiple plies at various orientations, combining one or more materials, are repeated or dropped in different zones of the structure, yielding the plydrops taper while ensuring physical continuity of the fibers in all composite layers. The orientation and thickness of each ply group in this reference sublaminate as well as its number of repetitions in the zones across the structure, are optimized using the Nelder-Mead algorithm in conjunction with parametric SAMCEF Finite Element Analyses, all integrated within SUNSPOT. The optimization objective is minimum weight for first ply failure strength. Maximum displacement constraints and economical manufacturing can be enforced additionally. Therefore, extended Tsai-Wu strength failure criteria were derived; new stiffness control criteria and a manufacturing complexity index were developed [1,2].
Failures at Attachment Holes in Brittle Matrix Laminates
Authors: Genin Guy M. , Hutchinson John W. 
Published: April 2011

Mechanical attachments for a brittle-matrix fiber-reinforced cross-ply composite are analyzed. Two model problems are considered: first, a bolt-loaded strut, and second, an infinitely-wide plate with evenly-spaced bolts. The possible failure mechanisms for the strut are identified, and the influence of bolt size, bolt location, bolt elasticity, and interfacial friction on these failure mechanisms and the associated failure loads are evaluated. The bolt spacing for the plate is identified that best takes advantage of a SiC/MAS cross-ply's ability to redistribute stresses through the mechanism of matrix cracking. Boundary value problems are solved using the finite element method. The cross-ply's constitutive behavior is described by the model of Genin and Hutchinson [1].
Fiber-Optic and Ultrasonic Measurements for In-Situ Cure Monitoring of Graphite/Epoxy Composites
Authors: Chen J. -Y. , Hoa S. V. , Jen C. -K. , Wang H. 
Published: April 2011

To produce high-quality composites with high density and low void content, the knowledge of cure process is very important, and the sensors capable of monitoring the cure process are therefore desirable. Since the term of "fully processed" should be a reflection of the ultimate material application, the objectives of the present work are to monitor how material properties have been developed during the cure and justify when "end-of-cure" has been achieved by measuring chemical and mechanical properties of the curing composites. As a reference, differential scanning calorimetry is used to evaluate the degree of cure while fiber-optic sensors are used to measure the evolution of process-induced strains, and ultrasonic sensors are used to monitor the development of viscoelastic properties of the curing composites. Moreover, an ultrasonic cure monitoring system has been developed, by using conventional broadband ultrasonic sensors together with clad buffer rods. The major merits of this system can be summarized as (i) workable inside an autoclave at high temperature (for example, up to 2500C if by water-cooling) and internal pressure (for example, 100 psi); (ii) high signal to spurious ultrasonic noise ratio, and high signal strength; (iii) suitable for longitudinal or shear wave measurement in reflection/transmission mode.
A New Rapid Immunohistochemical Staining Technique Using the EnVision Antibody Complex
Authors: Kämmerer Ulrike , Kapp Michaela , Gassel Andrea Maria , Richter Thomas , Tank Christian , Dietl Johannes , Ruck Peter 
Published: April 2011

Rapid immunohistochemical investigation, in addition to staining with hematoxylin and eosin, would be useful during intraoperative frozen section diagnosis in some cases. This study was undertaken to investigate whether the recently described EnVision system, a highly sensitive two-step immunohistochemical technique, could be modified for rapid immunostaining of frozen sections. Forty-five primary antibodies were tested on frozen sections from various different tissues. After fixation in acetone for 1 min and air-drying, the sections were incubated for 3 min each with the primary antibody, the EnVision complex (a large number of secondary antibodies and horseradish peroxidase coupled to a dextran backbone), and the chromogen (3,3′diaminobenzidine or 3-amino-9-ethylcarbazole). All reactions were carried out at 37C. Specific staining was seen with 38 antibodies (including HMB-45 and antibodies against keratin, vimentin, leukocyte common antigen, smooth muscle actin, synaptophysin, CD34, CD3, CD20, and prostate-specific antigen). A modification of the EnVision method allows the detection of a broad spectrum of antigens in frozen sections in less than 13 min. This method could be a useful new tool in frozen section diagnosis and research. (J Histochem Cytochem 49:623–630, 2001)
CYTOCHEMICAL OBSERVATIONS ON CHICKEN MONOCYTES MACROPHAGES AND GIANT CELLS IN TISSUE CULTURE
Authors: WEISS LEON PAUL , FAWCETT DON W. 
Published: April 2011

Cultures of leukocytes from chicken blood grown in fluid medium in roller flasks were stained for lipids, carbohydrates, phosphatase, esterase, and succinic dehydrogenase in order to study the cytochemical changes associated with the transformation of monocytes to macrophages, epithelioid cells and multinucleate giant cells. The great variability in cell form observed by previous investigators in such cultures was confirmed. The cells were usually round but not uncommonly were stellate or fusiform, sometimes bearing a striking similarity to fibroblasts, at other times resembling sheets of mesothelium. The factors determining their size and shape were obscure, but low pH seemed to favor the formation of giant cells. Monocytes of chicken blood were ordinarily devoid of stainable lipid, carbohydrate and enzymes. Macrophages and epithelioid cells which developed from them were negative for esterase, succinic dehydrogenase and alkaline phosphatase but gave a strong reaction for acid phosphatase, localized in their enlarged centrosphere or Golgi zone. This region also contained a saliva-resistant, periodic acid-Schiff positive material, probably a carbohydrate-protein complex and its relation to the enzyme acid phosphatase has been considered. Numerous small lipid droplets were disposed around the periphery of the Golgi zone. Giant cells occasionally contained glycogen. The acquisition of acid phosphatase by monocytes during their transformation to macrophages appeared to be related to their enhanced phagocytic activity.
A CHEMICAL AND HISTOCHEMICAL INVESTIGATION OF GLYCOGEN IN RAT LIVER AND PALATE FOLLOWING TREATMENT WITH VARIOUS FIXATIVES AND ETHYLENEDIAMINE TETRAACETIC ACID
Authors: TROTT J. R. , GORENSTEIN S. L. , PEIKOFF M. D. 
Published: April 2011

The loss of glycogen after fixation in acetic acid-alcohol-formalin as compared to immediate determination was found by chemical analysis to be from 5.2% to 13.8%. No appreciable difference could be seen histochemically. Chemical analysis of the glycogen content of liver fixed in acetic acid-alcohol-formalin and then treated in ethylenediamine tetracetic acid showed a total drop of 20.7 to 33.7%. Glycogen could still be adequately shown histochemically. Sections taken from liver fixed in 1% periodic acid in 10% formalin show greater amounts of glycogen, than those taken from acetic-acid-alcohol-formalin fixed tissue. After fixation in 1% periodic acid in 10% formalin and following treatment with ethylenediamine tetraacetic acid, very little glycogen could be demonstrated histochemically. In the palate, no glycogen could be demonstrated after fixation in acetic acid-alcohol-formalin, whereas quite heavy amounts could be seen in the prickle cell layers of the epithelium following fixation in 1% periodic acid in 10% formalin. Neither acetic acid-alcohol-formalin nor 1% periodic acid in 10% formalin are satisfactory fixatives if the tissue is to be further decalcified in ethylenediamine tetraacetic acid, if there are only small amounts of glycogen present. No adequate method of retaining glycogen in small amounts in tissue requiring decalcification can be suggested.
THE LOCALIZATION AND SIGNIFICANCE OF ARGININE AND CITRULLINE IN PROTEINS OF THE HAIR FOLLICLE
Authors: ROGERS G. E. 
Published: April 2011

The Sakaguchi reaction for arginine and the Ehrlich reagent for citrulline, which was modified to lessen tissue swelling, have been used to localize these amino acids in the inner sheath and the medulla layers in sections of actively growing hair follicles of the rat. The trichohyalin droplets are rich in arginine but gave no detectable reaction for citrulline. Conversely, the hardened substance of the inner sheath and of the medulla gave a relatively weak reaction for arginine but an intense one for citrulline. The presence of high concentrations of citrulline in the proteins of the hardened inner sheath and medulla has only recently been reported from chemical studies. The results support biochemical and electron microscope studies indicating a conversion of arginine residues into citrulline residues without protein breakdown, concomitant with the morphological transformation of trichohyalin droplets into the hardened fibrous protein of the inner sheath or the hardened amorphous material of the medulla. Other possible biochemical functions for the inner sheath and the medulla are also discussed.
DISTRIBUTION OF ESTERASES IN THE MYONEURAL JUNCTION OF THE STRIATED MUSCLE OF THE RAT
Authors: ERÄNKÖ O. , TERÄVÄINEN H. 
Published: April 2011

Distribution of esterases in the myoneural junction of the striated muscle of the rat was studied using acetylthiocholine, butyrylthiochobine and α-naphthyl acetate as substrates, together with selective inhibitors. Acetylcholinesterase activity was observed in the peripheral complex of synaptic folds. Nonspecific cholinesterase was detected in the peripheral complex of synaptic folds and the teloglia with approximately equal activities. Nonspecific esterase activity, present in tissues incubated with eserine, was marked in the terminal axon and was also present in the teloglia and synaptic folds.
HISTOCHEMICAL STUDIES OF THE OLFACTORY MUCOSA OF THE RABBIT
Authors: BURKHARDT BETTY J. , EHRMANTRAUT HARRY C. 
Published: April 2011

1. Tests of the olfactory mucosa of rabbits by five different methods indicate that cholinesterase is probably not present in any of the cells of this tissue. 2. Alkaline phosphatase and phosphamidase were not found in the olfactory receptors. 3. Acid phosphatase and sulfhydryl groups were found to be present in the receptors, and the presence of cytochrome oxidase was demonstrated in gross sections of turbinate tissue.
THE HISTOCHEMICAL DEMONSTRATION OF INDOLE DERIVATIVES BY THE ROSINDOLE REACTION OF E. FISCHER
Authors: GLENNER GEORGE G. 
Published: April 2011

1. The application of the rosindole reaction of E. Fischer to the histochemical localization of indole derivatives is described. This method demonstrates predominantly the tryptophan moiety of proteins and it therefore depends on the degree of protein fixation produced by formaldehyde. 2. The specificity of the rosindole reaction is established and the comparison is made between it and both the xanthydrol and post-coupled benzylidene reactions. 3. The facility of the histochemical technique as well as its specificity, sensitivity, and sharp localizability recommends the use of the rosindole reaction in routine histopathological investigation.
HISTOCHEMICAL DISTRIBUTION OF PHOSPHORYLASE IN RODENT BRAIN FROM NEWBORN TO ADULTS
Authors: SHIMIZU NOBUO , OKADA MASAAKI 
Published: April 2011

Phosphorylase activity of the brain of rats from newborn to adults was investigated histochemically by Takeuchi and Kuriaki's method, using the iodine reaction. Additional studies were made of the brain of adult guinea pigs, mice and rabbits. The phosphorylase of newborn rats was generally slight in activity, except for moderate or strong action in some structures: arachnoid membrane, choroid plexuses, ventricular walls, area postrema, pineal and subcommissural bodies, raphe of the medulla oblongata, some brain stem nuclei such as the nucleus of the mesencephalic tract and motor nucleus of the fifth nerve, nuclei of the facial and hypoglossal nerves. Slight reaction appeared in the ventral thalamic and habenular nuclei on the 3rd day, in the cerebral and cerebellar cortices and superior colliculus on the 5th day after birth. The enzyme activity showed a general increase at 14 days and reached the maximal intensity at about 21 days of age, while the arachnoid membrane, choroid plexuses amid raphe exhibited evident decrease of activity. The white matter showed an initial activity at different ages from 5 to 21 days, to attain maximal activity by 1 month. In the adult a moderate purple staining was consistently demonstrated in the area postrema, subcommissural body and ventricular walls. The neopallium as well as the superior colliculus and cerebellar cortex showed strong or moderate brownish purple color. Nuclei of the brain stem gave characteristic staining; a purple color was encountered in the nucleus of the mesencephalic tract and motor nucleus of the fifth nerve, nuclei of the facial and hypoglossal nerves, brown or purplish brown color occurring in the caudate nucleus, putamen, interpeduncular and inferior olivary nuclei.
STUDIES ON STREPTOCOCCAL HYALURONIDASE AND ANTIHYALURONIDASE. II. THE LOCALIZATION OF SITES OF ABSORPTION OF STREPTOCOCCAL HYALURONIDASE (GROUP C) WITH FLUORESCENT ANTIBODY
Authors: EMMART E. W. , COLE R. M. , MAY E. L. , LONGLEY J. B. 
Published: April 2011

In an earlier report it was shown that streptococcal hyaluronidase isolated from the culture medium of Group C, strain 7 is antigenic in rabbits (10, lOa). The present report demonstrates the following: 1. Antihyaluronidase globulin, isolated from the sera of rabbits immunized with streptococcal hyaluronidase, is capable of completely inhibiting in vitro the hydrolytic action of the enzyme upon hyaluronic acid. Conjugation of the antihyaluronidase globulin fraction to fluorescein isocyanate does not affect the inhibiting action of the antibody upon the hydrolytic activity of the enzyme. 2. Using the Coons fluorescent antibody technique, streptococcal hyaluronidase has been identified in tissues of mice following the injection of the enzyme in the caudal vein. 3. The treatment of control normal tissues with fluorescent antihyaluronidase globulin solution gave negative results as did the treatment of experimental tissues with fluorescent normal globulin. As an additional and highly specific control the staining action of the fluorescent antibody upon hyaluronidase could be blocked by preliminary absorption of the tissue with unconjugated antibody. 4. Streptococcal hyaluronidase when injected intravenously, is widely distributed in tissues of the body but is absorbed and retained in selected areas and cells. The localization of fluorescent antigen-antibody complex may be nuclear or cytoplasmic or both. The selection of specific cells within any given tissue suggests that the basis for absorption of the enzyme may be the functional or the physiological state of the cell as well as the histogenesis of the cell.
DEOXYRIBONUCLEIC ACID SYNTHESIS IN THE DEVELOPING MOUSE EMBRYO STUDIED WITH TRITIATED THYMIDINE
Authors: ATLAS M. , BOND V. P. , CRONKITE E. P. 
Published: April 2011

1. Tritiated thymidine was injected into mice of pregnancy ages 6, 7, 8, 9, 10, 11, 14, and 17 days. 2. The incorporation of the thymidine into the tissues of the embryo, uterus and placenta were studied by the method of stripping film autoradiography. 3. Thymidine is incorporated into uterine cells at all stages. The greatest amount of uptake is effected by endothelial cells. Decidual cells show good uptake at the beginning, less later. 4. Embryonic tissues do not show any noticeable uptake until the ninth day, and then only in the outer membrane tissues of the trophoblast cells, giant cells and yolk sac cells. 5. On the tenth day incorporation occurs mainly in the blood and mesenchyme cells. On succeeding days more incorporation is found in other embryonic tissue. The nervous system does not incorporate the thymidine noticeably until the fourteenth day.