Spongy Material Research Articles

Noise damper and pneumatic tire with compensation tread groove

A noise damper disposed in a tire cavity formed by a pneumatic tire and wheel rim is disclosed. A noise damper designed to use with a wheel rim comprises an annular body disposed around a damper-mounting portion of the wheel rim, and the annular body is made of a spongy material having an inside diameter of from 0.9 to 1.10 times an outside diameter of the damper-mounting portion. A noise damper designed to use with a pneumatic tire comprises an annular body disposed in a tire hollow, and the annular body is made of a spongy material having an outside diameter of from 1.00 to 1.10 times the maximum inside diameter of the tire hollow.

A Comparative Study of Thai and Australian Crocodile Bone for Use as a Potential Biomaterial

This study aims to characterize the structure and properties of crocodile bone to assess the potential for use in biomedical applications. Crocodile bone samples obtained from Thailand (Crocodylus siamensis) and Australia (Crocodylus porosus), being the tail and the tibia respectively, were treated to remove organic material and the inner spongy (trabecular) material. The dense cortical bone was used for comparative instrumental analyses. Specific comparisons were made against bovine cortical bone and pure synthetic hydroxyapatite. The material was then analyzed using simultaneous differential thermal analysis/thermogravimetric analysis (DTA/TGA), Fourier- Transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). Imaging of full bone samples was also conducted using an environmental scanning electron microscopy (ESEM). The SEM provided valuable information through the imaging of samples, showing a markedincrease in bone porosity for crocodile material when compared to bovine samples. The crystallinity and/or crystallite size of carbonated hydroxyapatite has been found to be lower than synthetic apatite, with the tibia being the least crystalline of the bone types studied. The crystallinity index (CI) is used as a measure of crystallite size and internal strain. The strain is affected by substitutions in the structure and these results provide a starting point for comparison of the resulting mechanical properties. There is a need for any biomaterial chosen for bone replacement to allow adequate osteointegration. Thus the study this far shows that crocodile bone is a very promising source of carbonated apatite for biomedical applications.

Delayed Degradation in a Resorbable Plating System

Resorbable plating systems are used extensively for craniofacial reconstruction, particularly in children. The systems provide rigid fixation while potentially minimizing the long-term drawbacks of permanent plating systems such as plate "migration," bone growth restriction, and imaging artifact. However, the need for active plate resorption represents both the strength and weakness of these fixation systems. We present four patients who underwent cranial vault remodeling using a resorbable plating system, following which the plates were palpable and observable for at least 2 years postoperatively. All required surgical removal. On gross inspection, the plates had been replaced by an encapsulated spongy material containing yellow, grainy, cloudy liquid. The bone underlying the plates was depressed and irregular in contour when compared with the adjacent bone. Microscopic studies showed a giant cell foreign-body reaction with crystalline material present in the cell vacuoles.

The restoration of anatomic form of atrophied alveolar processes of jaws with the help of bioimplant lioplast

The purpose of the present research was: 1. To investigate the opportunity of application of allogen osteoplastic materials such as Lioplast, received in Samara Tissue Bank of Samara State Medical University. 2. To work out a new technique of producing lyophilized allogen osteoplastic materials, such as Lioplast, with application of an ultrasonic method of clearing. 3. The development of various techniques of operative intervention on jaws for increase in volume of atrophied, as a result of secondary adentia, alveolar shoot. 4. The application of spongy allogen osteoplastic material as a skeleton for filling in surgical operations on jaws. 5. The demonstration of the Technique of a bone-periostic Lioplast 'sandwich' for formation of an alveolar shoot.

Complications involving the mediastinum after injection of Enteryx for GERD

The Food and Drug Administration approved the use of Enteryx (Microvasive Endoscopy, Boston Scientific Corp, Natick, Mass) for the treatment of GERD in April 2003. Enteryx is a biocompatible polymer that is injected intramuscularly into the lower esophageal sphincter (LES). The injections are made under fluoroscopy to ensure correct placement of the substance and to avoid inadvertent submucosal or transmural injection. The injection solution contains ethylene vinyl alcohol, which is dissolved in dimethyl sulfoxide (DMSO) and is mixed with tantalum, a radiopaque contrast agent. After injection into tissue, the DMSO rapidly dissipates by diffusion and the polymer precipitates as a spongy material. The latter initiates an acute and, eventually, chronic inflammatory response, leading to fibrous encapsulation of the polymer. Preliminary studies have shown Enteryx to be efficacious for control of symptoms and allows discontinuation of pharmacotherapy for GERD. The most common complication with Enteryx injection is chest pain, which occurs in over 90% of patients and usually is mild. Dysphagia also is fairly common, occurring in approximately 20% of patients, but this usually is of short duration and does not require therapy. To date, a major complication of Enteryx injection has not been reported. However, reported here are two cases of serious complications involving the mediastinum after Enteryx injection for GERD.

Biological evaluation of ChuangYuLing dressing-a multifunctional medicine carrying biomaterial.

The safety of Chuangyuling (CYL) dressing-a multifunctional medicine carrying biomaterial was evaluated in order to provide foundation for the application of CYL as material used in the wound healing. The traditional Chinese medicine (TCM) extract solution was compounded with scaffolds (gelatin and Bletilla hyacinthine gum), and then frozen and dried to form spongy and porous material CYL. According to the standard of biological evaluation of medical devices that was instituted by the ministry of health of China, the biological evaluation of CYL dressing was conducted. The results showed that all the contents of biological evaluation test consisting of acute toxicity, skin irritation, sensitization and cytotoxicity met the requirement of standards. It was concluded that the biomaterial carrying TCM (CYL dressing) is safe for application of wound healing.

THE KINETIC CONGLUTINATE OF THE CREEPER FRESHWATER MUSSEL, STROPHITUS UNDULATUS (SAY, 1817).

The conglutinate of the creeper, Strophitus undulaus (Say, 1817) (Unionoidea: Unionidae), was studied with light and scanning electron microscopy. This conglutinate has a very simple structure consisting of a homogeneous, spongy material containing the glochidia. Each glochidium is contained within its egg membrane and is tethered to this membrane by the glochidial thread. Within the female's marsupium, the glochidia are contained within the conglutinate. When they are expelled to the water the glochidia emerge through pores to the outside and become infective. The mechanism for pushing the glochidia out of the conglutinate is osmotic. The marsupium apparently bathes the conglutinates in a hypertonic solution. When conglutinates are expelled to the surrounding hypotonic water, the spongy material of the conglutinate swells, pushing the glochidia out through the pores. Unlike other conglutinates studied, that of S. undulatus displays a brief period of innate motion which may be adaptive in attracting a suitable host.

Homogenization in elastodynamics with force term depending on time

We extend the study on the homogenization problem for an elastic material containing a distributed array of gas bubbles to the case when the body force depends on time. By technically constructing an approximating sequence, we are able to show the convergence of semigroups and therefore prove the main result that such spongy material can be approximated by an elastic material without holes in the elastodynamics with the force term depending on time.

Ultrastructure of lower Paleozoic dyads from southern Ohio II: Dyadospora murusattenuata, functional and evolutionary considerations

Fossil cryptospore dyads consistent with published descriptions of Dyadospora murusattenuata fall into two general categories when examined with the TEM. Type I dyads are enclosed, and have a wall consisting of (1) an outer homogeneous layer that is present on non-contact surfaces, but absent in large part over the contact surface, (2) a middle layer composed of plate-shaped units, and (3) an innermost granular layer. The latter two layers are continuous over each of the dyad members. Type II dyads show a range of ultrastructural types, differing primarily with respect to the extent of a region of spongy wall material that occurs at the edge of the contact face. Thin regions and breaks present in the walls of many dyads and pseudodyads may represent primitive sutures. Ultrastructural analysis suggests the existence of at least two separate lineages of plants in the Late Ordovician and Early Silurian, but the phylogenetic relationship between these groups and to more recent land plants remains uncertain.

Homogenization for inhomogeneous elastic body containing gas bubbles

We consider the homogenization problem for an elastic material which contains a distributed array of gas bubbles in the first part of this research. We assume that the spacing of the holes and their diameters are of the same order of magnitude. The main result is that such a spongy material can be approximated by an elastic material with no holes. In the second part of this work, we extend the results to the elastodynamics. In both cases we derive expressions for the effective moduli of the limiting material.

Porous medium finite element model of the beating left ventricle.

The axisymmetric model described represents myocardial tissue as a spongy anisotropic viscoelastic material. It includes torsion around the axis of symmetry of the ventricle, transmural variation of fiber angle, and redistribution of intracoronary blood in the myocardial wall. In simulations, end-systolic principal strains were equal to 0.45, -0.01, and -0.24 at two-thirds of the wall thickness from the epicardium and 0.26, 0.00, and -0.19 at one-third of the wall thickness from the epicardium. The direction of maximal shortening varied by less than 30 degrees from epicardium to endocardium, whereas fiber direction varied by greater than 100 degrees from epicardium to endocardium. During a normal cardiac cycle peak, equatorial intramyocardial pressure differed by less than 5% from peak intraventricular pressure. When redistribution of intracoronary blood in the ventricular wall was suppressed, peak equatorial intramyocardial pressure was found to exceed peak intraventricular pressure by greater than 30%. Simulated contraction of an unloaded left ventricle (left ventricular pressure = 0 kPa) produced similar magnitude for systolic intramyocardial pressures as the normal cardiac cycle. Transmural systolic fiber stress distribution was very sensitive to the chosen transmural fiber angle distribution.

A spectroscopic ellipsometry study of the growth and microstructure of glow-discharge amorphous and microcrystalline silicon films

Spectroscopic ellipsometry (SE) has been used to study the surface, microstructure, and optical properties of glow-discharge deposited amorphous and microcrystalline silicon films. The SE data has been analyzed using multilayer models, effective medium approximation, and linear regression analysis. The studies have shown that with increasing rf power and silane dilution, a gradual transition from good (dense) a-Si:H to a spongy material with a large density deficit, and then to a microcrystalline material is obtained. A quantitative analysis of the microstructure of a-Si:H films with growth parameters has been carried out. Combined with infrared and x-ray diffraction measurements, the results have been explained in terms of a nucleation and growth model.

Continuous alcohol fermentation in an immobilized cell rotating disk reactor

The increasing interest in alcohol fermentation over these last years because of the energy crisis has been demonstrated by an increase in scientific research. After a brief analysis of the main results of the literature in the field of alcohol fermentation reactors, the use of a new type of immobilized cell reactor [the rotating biological surface (RBS) reactor] was studied. As is well known, the RBS reactor is a form of fixed-film reactor and can be described as a dynamic trickling filter. Our experimental apparatus employed a spongy material to trap the yeast cells on the disks. The results of fermentations carried out in the RBS reactor working in batch, in continuous with cell support, and in continuous without cell support have been presented in order to compare the different productivities and to assess the performance of the RBS immobilized cell reactor. An ethanol productivity of 7.1 g/L h was achieved in the RBS-ICR at a dilution rate of 0.3 h(-1), 2.5 times higher than the maximum productivity obtained in the RBS reactor without support at a lower dilution rate. The adoption of a spongy material as a cell immobilizer, combined with the use of the RBS reactor, enhances the particular advantages of both systems.

ULTRASTRUCTURE AND DEVELOPMENT OF THE MICROSPORANGIUM OF PSEUDOTSUGA MENZIESII (MIRB.) FRANCO. I. DORMANT STAGES

The dormant (mid‐November to mid‐February) microsporangia of Pseudotsuga menziesii (Douglas‐fir) contain pollen mother cells (PMC's) in diffuse diplotene, surrounded by 1–2 layers of tapetal cells and 3–4 layers of microsporangial wall cells. At the beginning of dormancy, PMC's are large and their walls are lysed. The cell walls contain a thick layer of loosely‐arranged fibrils which are produced in large vesicles in the PMC cytoplasm and are secreted across the plasma membrane. PMC's contain several layers of rough ER. The inner tangential and the radial walls of the tapetal cells are lysed. During dormancy the PMC's form many new autophagic vacuoles, the chromatin consists of a network of fine threads comprised of medium‐sized granules of uniform size and the nucleoli split. The outer tapetal wall is thick and becomes encrusted by an irregular lipid layer. The tapetal cytoplasm is similar to the PMC cytoplasm but is devoid of amyloplasts. The tapetal cytoplasm shows secretory activity at the beginning of dormancy and again near the end of dormancy. The later secretory activity results in the deposition of a spongy material, especially along the radial and inner walls of the tapetal cells. Tapetal cells contain 1–2 large nuclei which show prominent and irregular clumps of chromatin. Subcellular developmental changes occur in the dormant microsporangia of Pseudotsuga in much the same manner as has been reported for Pinus.

Mechanism of intranuclear crystal formation of herpes simplex virus as revealed by the negative staining of thin sections.

Structural alterations induced in HeLa cells by herpes simplex virus and the mechanism whereby the virus is formed in the nucleus in crystal arrays were studied by electron microscopy with both the usual and negatively stained sections. Aggregates of granular and filamentous material were observed in the cytoplasm of infected cells with both sections. On the other hand, no remarkable alterations in appearance of the cytoplasmic ground substance were observed with the usual sections of infected cells. However, the cytoplasmic ground substance of infected cells when negatively stained consisted of granular material which was different in appearance from the spongy material constituting the cytoplasmic matrix of uninfected cells. In the nucleus of infected cells, complexes consisting of round bodies, amorphous material, aggregates of uniform granules in rows, and viral crystals were often observed near the nuclear membrane in both types of sections. Examinations of the granular aggregates with negatively stained sections suggested that each granule represents a subunit and that the several adjoining subunits (approximately eight) constitute the requirement for formation of a single viral capsid with a core. Thus, rapid and simultaneous formation of the core and capsid within the aggregate would replace the rows of the granules with the viral crystal. The advantages of negative staining of thin sections for visualization of fine structural alterations are discussed.

Isolation, structure and composition of cyst wall of Schizopyrenus russelli.

SYNOPSIS. A procedure is described for the isolation of cyst wall of Schizopyrenus russelli free of cytoplasmic material. It has 27.3% protein, 37.5% carbohydrate (of which 13.1% is cellulose), and 15.1% lipids. Sialic acid is absent. It has a relatively electrondense inner thick layer and a less electron‐dense outer thin layer. The space between the 2 layers is 25 nm in younger cysts and 2.5 μ in fully mature cysts. This space is filled with a fibrillar spongy material likely to be cellulose.

Microscopical Evaluation of Cellulose Esters with Low Degrees of Substitution

The effects on cotton of esterification to low degrees of substitution have been investi gated by light and electron microscopy. Observations were made on partially esterified celluloses which included esters of acetic, palmitic, stearic, 12-hydroxystearic, linoleic, and ricinoleic acids and of the aromatic benzoic, cinnamic, naphthoic, and pkenylundecanoic acids. The uniformity of the esterification of cellulose was followed by dyeing and swelling techniques. Refractive index measurements were used to follow changes in optical anisotropy which accompanied the chemical modification. The average refractive indices of cellulose esters containing aromatic groups were greater than those of the esters with aliphatic substituents, the greatest difference being between indices measured perpendicu lar to the fiber axis. The normal fibrillate texture of the scoured surface appeared to become smooth upon esterification. Fragmentation of the esters in water in a laboratory blendor produced long strands of fibrillate material intermingled with clumps of spongy or amorphous material. On de-esterification of the fragments with an alcoholic base, the structure of the material reverted to that of unesterified cotton—fibrils became distinct and, in some cases, saponification proceeded to a stage where hydrocellulose-like particles were formed. , Many of the esterified fibers of low degrees of substitution swelled in the conventional methacrylate embedding technique. The swelling caused the cell wall to separate into layers, and the internal structure could then be studied by examination of thin sections of these fibers with the electron microscope. By use of an alternative embedding medium, aqueous polyvinyl alcohol, in the preparation of thin sections, compact unlayered struc tures of the esterified cottons were obtained. This permitted observations of the undis turbed structure of the modified cottons. Both types of observations were used in the microscopical evaluation of cotton fibers esterified to low degree of substitution to demonstrate structural changes brought about by the esterification reaction.

MECHANICAL BEHAVIOR OF TWISTED SLIVER

In this paper the correspondence of the induced pressure in twisted sliver with the compressed paessure in loaded wad was measured under such equilibrium condition that both of frictional forces at the two ends of metal wire inserted partly in the wool wad and partly in the twisted wool sliver were balanced (see fig. 1). At the balanced frictional state (see fig. 2), the experimental relations between the twist angle θ (deg/cm) of sliver having fullness (1-e)s and the applied load R (g/cm2) of wad having fullness (1-e)w are shown in fig. 4. On the other hand, the effect of R on the withdrawal force Fw (g/cm) of single fibre from this wad was described by inverse sigmosoidal curve in fig. 5, and the dependence of Fw on R/(1-e)w was obtained linearly as shown in fig. 7. Thus, frictional coefficient of wool fibre was estimated to μ0=0.26 by Postle-Ingham's method23). And then, the dependence of average frictional force Ft (g/cm) of a fibre in wool sliver on its twist number n (cm-1) was estimated from the load-elongation curves of twisted wool sliver. In fig. 10, this relation of Ft and n was plotted exponentially.From these experimental results, detailed assignments of the mechanical state of a fibre in twisted sliver have been made as follows:(1) In fig. 12 it is shown that the value of radial pressure Pw (g/cm) produced on the unit length of axial centre line of twisted sliver increases quadratically as twist number n increases.(2) Inter-fibre frictional force Ft of twisted sliver increases with two sets of factors: one is bulk density increment of sliver by twisting, and another the curvature increment of fibre arrangement. The observed values of the former efiects on the frictional force of single fibre are given as Fw/4 in fig. 10, and those of the latter effect as (Ft-(Fw/4)) in fig. 10.(3) The tortional behavior of wool sliver as a whole is similar to the spongy material, for the orientation of fibre in a twisted sliver was not arranged to regular spiral configuration, but intercected mutually as the results of fibre migrations. This makes possible to suggest that the value of inter-fiber frictional cofficient μ in twisted sliver is larger than that of μ0 in untwisted wool wad. Actually, inserting the observed values of Ft/(Fw/4), the average ratio of frictional force along the generating line of unit length, into eqs. (6), (7), calculated value of μ was about 1.

繊維系の撚り構造と弾性的性質

In this paper the correspondence of the induced pressure in twisted sliver with the compressed paessure in loaded wad was measured under such equilibrium condition that both of frictional forces at the two ends of metal wire inserted partly in the wool wad and partly in the twisted wool sliver were balanced (see fig. 1). At the balanced frictional state (see fig. 2), the experimental relations between the twist angle θ (deg/cm) of sliver having fullness (1-ε)s and the applied load R (g/cm2) of wad having fullness (1-ε)w are shown in fig. 4. On the other hand, the effect of R on the withdrawal force Fw (g/cm) of single fibre from this wad was described by inverse sigmosoidal curve in fig. 5, and the dependence of Fw on R/(1-ε)w was obtained linearly as shown in fig. 7. Thus, frictional coefficient of wool fibre was estimated to μ0=0.26 by Postle-Ingham's method23). And then, the dependence of average frictional force Ft (g/cm) of a fibre in wool sliver on its twist number n (cm-1) was estimated from the load-elongation curves of twisted wool sliver. In fig. 10, this relation of Ft and n was plotted exponentially.From these experimental results, detailed assignments of the mechanical state of a fibre in twisted sliver have been made as follows:(1) In fig. 12 it is shown that the value of radial pressure Pw (g/cm) produced on the unit length of axial centre line of twisted sliver increases quadratically as twist number n increases.(2) Inter-fibre frictional force Ft of twisted sliver increases with two sets of factors: one is bulk density increment of sliver by twisting, and another the curvature increment of fibre arrangement. The observed values of the former efiects on the frictional force of single fibre are given as Fw/4 in fig. 10, and those of the latter effect as (Ft-(Fw/4)) in fig. 10.(3) The tortional behavior of wool sliver as a whole is similar to the spongy material, for the orientation of fibre in a twisted sliver was not arranged to regular spiral configuration, but intercected mutually as the results of fibre migrations. This makes possible to suggest that the value of inter-fiber frictional cofficient μ in twisted sliver is larger than that of μ0 in untwisted wool wad. Actually, inserting the observed values of Ft/(Fw/4), the average ratio of frictional force along the generating line of unit length, into eqs. (6), (7), calculated value of μ was about 1.

A Carved Antler Human Face from Umatilla, Oregon

In the Lillard Collection primarily comprising archaeological materials from California now permanently housed in the University of California Museum of Anthropology, is a prehistoric artifact from Oregon which deserves special mention.The specimen (Fig. 48) which is broken now measures 8.1 cm. in length, 3.7 cm. in width and 8 cm. in thickness. In cross section it is slightly curved from the natural contour of the original material. The inner convexity bears traces of the interior spongy or cancellous material of the antler.