Sheath Type Research Articles

Formulas for Wood Shear Walls

Formulas are presented for the analysis of typical wood-frame shear walls with sheathing attached by nails or other types of discrete fasteners. Formulas are derived for the sheathing fastener forces, for the linear shear stiffness of a wall, and for the nonlinear shear load-strain behavior of a wall. These formulas are shown to be in agreement with the results of load tests and of finite element, linear, and nonlinear analyses. Details of the load tests and finite element analyses are given. The formulas are relatively simple and should be applicable to the design of wood frame shear walls with plywood or other types of sheathing.

Optical diffraction as a tool for semiautomatic, quantitative analysis of tissue specimens.

Optical diffraction was tested on electron micrographs of normal and malformed myelin sheaths as a method for semiautomatic quantitative analysis of tissue specimens. Both normal and malformed myelin sheaths were chosen for the analysis because of their characteristic internal structure and its alteration as a result of malformation. Optical diffraction patterns were obtained by means of an optical diffractometer coupled with a digital detector. The spacing and arrangement of the components of various types of myelin sheath were automatically calculated and determined and the results were verified with discriminant analysis. Out of 27 parameters of the radial and out of 25 parameters of the angular distributions of diffracted light intensity, 6 and 11, respectively, were found to have good discriminative power and were used for classification of myelin sheaths. The accuracy of automatic classification was tested by comparison with myelin sheath types of known origin. The samples visually similar by their appearance, e.g. control and regenerating myelin sheaths, were automatically classified with accuracy of 69%, whereas others were classified appropriately with 88-100% accuracy. It is believed that this kind of analysis may successfully be applied for specimens of other tissues and/or organs.

Influences of Pheromone Dispenser and Trap Placement on Trapping Carpenterworm 1 Moths in North Dakota and Mississippi

Carpenterworm ( Prionoxystus robiniae Peck) attractant dispensers, trap height, and trap color were evaluated for attractiveness to the male carpenterworm in Mississippi (MS) and North Dakota (ND). The effect of understory density on trap site was also checked. In the humid MS hardwood forest, a standard cotton wick dispenser baited with synthetic sex attractant (Z,E) -3,5 tetradecadien-1-ol acetate was more effective in attracting males than a sheath type dispenser, but in the drier ND environment, it was less effective than a sheath dispenser or any of four other dispensers. Trap catches in MS generally increased with trap height, but in ND, most moths were caught between the tree canopy and the undergrowth. In MS, the capture rate in 1.5 m high traps was not influenced by light or medium understory densities, but heavy understory reduced trap catches. Trap color had no effect on the rate of moths captured.

Tumors Of The Pilosebaceous Unit Induced In The Rat By The Intravenous Administration Of 7, 12-Dimethylbenz[A]Anthracene

Six of 70 female Sprague-Dawley rats given a single intravenous injection of 7,12-dimethylbenz[a]anthracene (DMBA) developed 7 pilosebaceous tumors. Two of the tumors showed differentiation toward the upper portion of the pilosebaceous unit while 5 showed differentiation toward the lower portion. Each tumor was examined histochemically for the presence of inner root sheath keratin of the hair follicle using the carbamido diacetyl reaction for citrulline and for hair shaft keratin using boiling ninhydrin reagent. The 2 tumors of the upper portion of the pilosebaceous unit were sebaceous adenomas which were accompained by a keratinizing epithelim like that of the sebaceous gland duct and upper pilosebaceous canal. Histochemically, the keratin was not like that of hair shaft nor inner root sheath. The 5 tumors showing differentiation toward components of the lower pilosebaceous unit were trichoepitheliomas. They were composed of structures which, to varying degrees, recapitulated the organization of the normal hair follicle. Within these follicular structures, both inner root sheath and hair shaft type keratins were found. The occurrence of skin tumors after the intravenous administration of DMBA was unexpected since it is uncommon for skin tumors to be produced by the systematic administration of chemical carcinogens and they have never been described after the oral administration of DMBA. That the route of administration may influence tumor production with this carcinogen is suggested by the fact that the only other reported tumors, which were squamous carcinomas, also followed intravenous injection of DMBA.

Leaf anatomy of Cunoniaceae

A study of leaf anatomy of 24 genera of Cunoniaceae was made. The prevailing petiole vasculature is a nearly complete, usually adaxially flattened, medullated cylinder with the flat dorsal segment separated from the ventral arc. Medullary and cortical vasculation in Codia, Cunonia, Geissois and Pancheria is correlated with an increase in leaf coriaceousness. Very few characters are uniformly found in leaves of all species; these are druse or prismatic crystals, bifacial mesophyll and unicellular and simple trichomes. In most species vein sheathing occurs. Characters of the lamina that show variation and are useful in generic delimitation are: trichome type, presence of a hypodermis, occurrence of mucilaginous cells, presence of specialized terminal veinlet cells, major and higher order venation patterns, vein sheathing type, and mature stomatal types. Stomata are of the anomocytic, paracytic or anisocytic types. Leaves of various cunoniaceous species of xerophytic environments exhibit a leathery texture, thicker cuticle, more intensive sclerification along the veins, a sclerified hypodermis, and an increase in the amount of vascular tissue per unit area. Leaf anatomy does not provide immediate clues toward elucidating the relationships of cunoniaceous genera.

Fine Structure of the Eighth Nerve Ganglion in the Toad

In the eighth nerve ganglion of the toad, the nerve cells could be divided microscopically into small dark cells and large light cells. About 20% of the nerve cells in the ganglion were myelinated with compact myeline and were recognized as corresponding to the large light cells. In the cytoplasm of the dark cells, there was an abundance of Nissl substance and mitochondria, while in the perikaryon of the light cells, the granular aggregates and mitochondrial profiles were widely dispersed, but neurofilaments were obviously scattered. Electron-microscopically, the small dark cells could be divided further into the unmyelinated neuron ensheathed with a single layer of the satellite cell cytoplasm and the neuron encapsulated by a sheath consisting of loose myelin. The large light neurons have the compact myelin looked like the myelinated nerve fibers because their figures resembled elongated spindles which were connected with heavy axons leaving their opposite poles and their perikaryal peculiarity was provided with abundant neurofilaments in their perikarya. The fine structures of both the above-mentioned neurons were compared with those of the various neurons in the acoustic ganglia of the rat, goldfish, guinea pig and cat. Finally, it was concluded that no significant relationship could be recognized between the structural features of perikarya of those neurons and the types of myelin sheath surrounding their perikarya.

High‐Frequency Backscattering From a Perfectly Conducting Sphere Coated With a Radially Inhomogeneous Dielectric

In this paper, the backscattered electric field is derived when a plane electromagnetic wave is incident upon a perfectly conducting sphere coated with a radially inhomogeneous dielectric. The Mie series is obtained and then subjected to an asymptotic analysis that is valid for very short wave‐lengths. In particular, the first two terms for the reflected portion of the electric field are derived and the formulation for the creeping wave contribution is presented. Also, a numerical computation of the monostatic cross section is performed for various thicknesses of the coating by considering the reflected portion of the backscattered electric field. It is shown that this particular type of inhomogeneous sheath reduces considerably the monostatic cross section of the perfectly conducting sphere as its thickness increases.

Thermodynamics in HCl in water-methylcellosolve mixtures—I. standard potentials of the silver/silver-chloride electrode

The standard potentials of the Ag/AgCl electrode in water-methylcellosolve mixtures have been determined at 25, 30, 35, 40 and 45°C. The values of E m o in each solvent is determined as a function of temperature. The plot of E m o against the reciprocal dielectric constant at 25°C indicates the existence of three types of solvation sheaths of the ions. The non-electrostatic part of the standard free energy and entropy has been evaluated. The results can be interpreted in terms of the breakdown of the water structure by the addition of the organic solvent.

Use of epoxy compounds in structural elements and insulation in the Kislogubsk tidal power station

1. Epoxy foam heat-and-water insulation and epoxy-pitch waterproofing have been found to be suitable for structures in regions with a severe climate, and in particular for tidal power stations built by the floating method. 2. Industrial experience in the construction of the Kislogubsk tidal power station has shown the advantages of using epoxy plastic solutions for constructing waterproofing seams and repairing defects in the concreting of thin-walled concrete structures. 3. The coating technology is simple and requires no special equipment. 4. Subsequent service experience of the concrete structures of the Kislogubsk tidal power station and insulating coatings in the Barents Sea confirms the long life of the compositions used, and the results can be taken into consideration when devising new types of sheathing.

The genus Ceratocystis in Ontario

From Ontario hardwoods and conifers, 234 collections were examined for Ceratocystis and associated stains and vectors. Most previously described species, including many type specimens, were also studied.Among morphological characters used to separate species of Ceratocystis, those of the ascospores are the most reliable and are stressed in this study. Three-dimensional examination of ascospores, particularly in species possessing spores with sheaths, is necessary to determine spore shape accurately. Four ascospore sheath types are recognized: uniform, hat-shaped, double-brimmed, and quadrangular.A preliminary survey indicates that the bark-beetles Ips pini (Say) and Orthotomicus caelatus (Eich.) may be principal vectors for several Ceratocystis spp. on Ontario conifers.Based mainly on ascospore characters, a key to 60 species of Ceratocystis is provided. The species C. galeiformis Bakshi, C. obscura (Davids.) Hunt, C. polonica (Siem.) Hunt, and C. serpens (Goid.) C. Moreau are excluded. It is proposed that C. ambrosia Bakshi, C. capillifera (Hedgc.) C. Moreau, C. pluriannulata (Hedgc.) C. Moreau, and C. schrenkiana (Hedge.) C. Moreau be considered synonyms of C. pilifera (Fr.) C. Moreau and that C. vesca Davids. be treated as a synonym of C. olivacea (Math.) Hunt. The following species, described since Hunt's key was published, are included: C. bicolor (Davids, and Wells) Davids., C. brevicollis Davids., C. brunnea Davids., C. brunneocrinita Wright and Cain, C. dryocoetidis Kendrick and Molnar, C. europhioides Wright and Cain, C. falcata Wright and Cain, C. huntii Robinson, C. megalobrunnea Davids, and Toole, C. nigra Davids., C. perfecta Davids., C. tremuloaurea Davids, and Hinds, C. truncicola (Davids.) Griffin comb. nov. Eleven new species are described in this paper.Descriptions, figures, and distribution data are provided for most of the 32 species of Ceratocystis encountered in Ontario. The following previously described species were collected: C. bicolor (Davids. and Wells) Davids., C. brunneocrinita Wright and Cain, C. coerulescens (Munch) Bakshi, C. europhioides Wright and Cain, C.fimbriata Ell. and Halst., C. huntii Robinson, C. ips (Rumb.) C. Moreau, C. major (Van Beyma) C. Moreau, C. minor (Hedgc.) Hunt, C. minuta (Siem.) Hunt, C. nigra Davids., C. olivacea (Math.) Hunt, C. perparvispora Hunt, C. piceae (Munch) Bakshi, C. pilifera (Fr.) C. Moreau, C. sagmatospora Wright and Cain, C. stenoceras (Robak) C. Moreau, C. tenella Davids., C. tetropii (Math.) Hunt, C. truncicola (Davids.) Griffin comb, nov., and C. ulmi (Buism.) C. Moreau.The following new species are described by the author: C. acericola, C. allantospora, C. angusticollis, C. capitata, C. crassivaginata, C. dolominuta, C. magnifica, C. ochracea, C. pallida, C. spinulosa, and C. stenospora.

Remote Reading Bottom-Hole Pressure Gauges- An Evaluation of Installation Techniques And Practical Applications

Abstract Since 1959, 50 field installations of remote reading bottom-hole pressure gauges have been made on the Cedar Creek anticline in Eastern Montana. The installations were made in wells 9,000 ft deep with bottom-hole temperatures as high as 200F, and included both taut wire and bourdon tube bottom-hole pressure transducers. The initial installations had short periods of operational life because of cable and instrument failures. Continued investigation of installation techniques and types of cable have resulted in operational periods in excess of one year with an expected life of two years or more. Eleven types of cables were tested with various types of insulation and protective sheaths, various outside diameters, and solid and stranded conductors. Several methods of splicing were evaluated for mechanical strength and insulating qualities; a new cable clamp had to be designed; dawn-hole and surface conductor pack-offs were revised; and surface handling techniques had to be developed. Several case histories of practical applications are cited, which include bottom-hale pressure build-up surveys, water flood observation well surveillance and performances of producing wells. The installation cost figures included demonstrate that, although the use of remote bottom-hole pressure gauges cannot be justified in every producing well of this depth, installation in most key observation wells can be justified, depending upon the volume and importance of the data required. Practical installations of remote reading bottom-hole pressure gauges can now be made and have resulted in another valuable tool available to the petroleum engineer. Introduction Accurate and current down-hole pressure data are desirable to produce oil and gas wells at their optimum rate and by the most economical means. A permanently installed bottom-hole pressure gauge is an instrument which can provide such data for production personnel and engineers. The installation of remote reading bottom-hole pressure gauges in every producing well would be ideal from the standpoint of determining producing and static pressures and for detecting subtle equipment malfunctions. However, limited life expectancy and the existence of other indirect methods for determining bottom-hole pressure data have previously limited these installations to specialized cases. The development of the German-produced bottom-hole pressure transmitting system and its widespread use in the Schoonebeek and other fields in Europe prompted the investigation of practical applications in various Shell areas in the United States in 1958. Initial installations in the Pacific Coast, Texas and Rocky Mountain areas resulted in varying degrees of success. Fairly successful installations were made in relatively shallow wells, but the results were disappointing in wells ranging in depth from 6,000 to 9,000 ft. Short operational life and consequent expense were experienced in these wells. In view of the potential application of a direct reading and permanently installed pressure gauge, the development of practical installation techniques was classified as a General Development and Evaluation Project by Shell Oil and a sum of money was granted to the Rocky Mountain area for investigation and development of installation procedures and equipment evaluation. From these investigations, installation techniques have been refined and operating expenses have been reduced, permitting greater utilization and justification for these instruments. The remote reading bottom-hole pressure gauge has become an operational and a practical tool for wells producing highly aromatic hydrocarbons at depths to 9,000 ft, temperatures to 220F (104C) and pressures to 3,500 psi. Presently installed instruments have operated for an average duration of one year or more, and two year runs have been quite common. Installations in wells having less severe conditions should operate for significantly longer periods. This paper presents the experience obtained to date with these gauges and includes recommended installation and operating practices and materials. Theory of Operation of Existing Instruments To date two operational gauges are available for measuring bottomhole pressures on a remote reading basis. They are the German-produced taut wire gauge and the United States- produced bourdon tube-type gauge. The taut wire gauge was developed in 1948 and tested in German oil fields during 1950. JPT P. 1303^

Nitrile Rubbers and Vinyl Polymer Mixtures

Abstract The outstanding resistance to abrasion, oil, fire and ozone of vulcanized nitrile rubber/PVC blends has stimulated cable manufacturers throughout the world. In this paper the effect of polymer properties on mixing conditions is discussed and physical properties resulting from different mixing conditions reviewed. The physical (including electrical) properties of vulcanized and unvulcanized nitrile rubber/ PVC blends are related to the use of these blends in covering electric cables. Comparisons are made with other types of sheathing and insulating materials and existing potential uses of nitrile rubber/PVC blends in cable coverings are discussed.

An Alternate to Lead for Telephone Cables

In order to permit rapid expansion of telephone cable production to meet unprecedented postwar requirements, a new type of sheath was developed as an alternative to lead-antimony sheath for paper i...

Flow Characteristics of Some Lead Cable Sheath at Temperatures Above Atmospheric

Abstract This paper gives results of an investigation on three types of lead cable sheath differing only in the antimony content, which was, respectively, 0.06, 0.6, and 1.2 per cent. At room temperature all three compositions elongated at more or less fixed rates with loads as low as 245 lb. per sq. in. The results would indicate that a similar behavior would be obtained with still lower loads and that the behavior of lead at 70 deg. fahr. should be similar to that of plain carbon steel at a temperature above its equicohesive range. Increasing antimony content does not result in a decrease in the rate of flow at the lower temperatures, but in a lowered resistance to creep. At a temperature of 80 to 120 deg. cent. the higher antimony content results in a decrease in the rate of creep, while the lower antimony results in a comparatively high rate of creep.

Protection of wood from moisture

In recent years, cold formed steel (CFS) buildings have been recognized as viable alternatives to reinforced concrete buildings especially in seismic areas. This is because they are lightweight, fast to construct, recyclable, dimensionally stable, and do not need formworks. Under vertical loading the design principles of these buildings are well established and codified, however, under lateral loadings such as earthquake loads efficient design is needed. In this paper the effects of sheathing material type on the cyclic lateral load behavior of CFS walls were investigated. Ten full scale CFS wall specimens sheathed with four different material types were tested under lateral cyclic loads. The sheathing types are Trapezoidal steel sheet, steel sheet, reinforced cement board, and thin ribbed steel sheet shotcreted with cement mortar.The effect of wall foundation connection details on the lateral load response of the walls were also investigated. Test results indicate that the lateral load carrying capacities of the walls increased by about 3 times when sheathed with the proposed materials. Furthermore specimens sheathed with steel sheets have almost the same lateral load carrying capacities of specimens sheathed with Trapezoidal steel sheets. However the hysteresis damping is higher in the steel sheet sheathed specimens. That means corrugating the steel sheets as Trapezoidal will not increase the strength and damping characteristics of the walls. Walls sheathed with 12 mm thick reinforced cement boards show 1.5 times higher lateral load carrying capacity than all the tested specimens. Depending on the material sheathing type and the sheathing thickness the specimens fail due to local failure in the edge studs, or screw tears out or buckling of the steel sheet. Lastly CFS wall lateral permanent deformations can be reduced by improving the wall-foundation connection details.