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Sheath

A sheath is a close-fitting protective case or covering, most commonly used to enclose the blade of a sword, knife, or similar edged weapon, thereby safeguarding the edge from damage and allowing safe handling and transport.^[1] The term derives from the Old English scǣþ, related to Germanic roots meaning "to separate" or "divide," which underscores its role in isolating and protecting the enclosed object.^[1] Historically, sheaths—often referred to as scabbards for swords—date back to the Bronze Age, serving both practical purposes like preventing rust and injury, and symbolic ones as status indicators through elaborate materials such as leather, wood, metal fittings, and decorative inlays.^[2] Archaeological examples, including Iron Age specimens from sites like Kirkburn in East Yorkshire, demonstrate their construction from organic and metallic components, sometimes featuring intricate chapes (metal tips) for reinforcement.^[3] In medieval and later periods, scabbards were suspended from belts or baldrics, evolving in design to accommodate various sword types while reflecting cultural and martial significance.^[2] In biological contexts, a sheath denotes an enclosing or supportive structure that protects underlying tissues or facilitates function, such as the leaf sheath in grasses and monocots, where the lower leaf base forms a tubular wrap around the stem for support and protection.^[4] Another prominent example is the myelin sheath, a multilayered lipid-rich membrane formed by glial cells that insulates neuronal axons, enabling rapid conduction of electrical impulses essential for nervous system efficiency.^[5] Damage to the myelin sheath, as in multiple sclerosis, disrupts signal transmission and underlies various neurological disorders.^[6] Anatomically, sheaths include the tendon sheath, a synovial-lined tube of fibrous tissue that surrounds tendons in areas of friction, such as joints, providing lubrication via synovial fluid to ensure smooth gliding during movement.^[7] Inflammation of these sheaths, known as tenosynovitis, can impair mobility and is common in repetitive strain conditions.^[7] Beyond these fields, the concept extends to engineering applications, like the insulating sheath around electrical cables, but its core usages remain rooted in protection and enclosure across natural and artificial domains.^[1]

Etymology and General Definition

Linguistic Origins

The word "sheath" enters English from Old English scēath or sceaþ, denoting a case or covering, particularly for a blade, with the earliest recorded uses appearing in Old English texts from the period before 1150.^[8] This term derives from Proto-Germanic \skaiþō or \skaithō, meaning "division" or "separation," reflecting the idea of a split or divided structure designed to enclose an object like a sword.^[9]^[1] The Proto-Germanic root traces further to the Proto-Indo-European \skei-, associated with "to cut" or "split," evoking the notion of creating a cleft for insertion.^[9]^[1] By Middle English, around the 12th century, the form evolved to shethe or shæþe, maintaining its core sense as a scabbard while broadening to general protective enclosures by the late 14th or early 15th century, as seen in texts such as the Promptorium Parvulorum (c. 1440).^[8]^[9] In scientific nomenclature, particularly biology, the English "sheath" draws conceptual influence from Latin vāgīna, meaning "sheath" or "scabbard," which was adopted in medical Latin from the 17th century to describe enclosing structures, paralleling the Germanic term's application to tubular coverings.^[10] Cognates persist in modern Germanic languages, such as German Scheide (scabbard or sheath) and Dutch schede, both retaining the sense of division or enclosure from the shared Proto-Germanic root.^[9]^[11] In Romance languages, equivalents like French gaine (a covering or casing) emerged separately but convey similar protective connotations, often used for sheaths in technical contexts.^[12]^[11]

Core Meaning and Variations

A sheath is defined as a close-fitting cover or case, typically tubular in form, designed to enclose, protect, or support an elongated object or structure.^[1]^[13] This primary meaning emphasizes its role as a protective envelope that conforms closely to the item it surrounds, distinguishing it from looser enclosures. Sheaths exhibit key variations across structural, functional, and contextual dimensions. Structurally, they range from rigid forms, such as wooden scabbards used for swords, to flexible variants like leather or synthetic coverings for smaller blades or cables.^[14] Functionally, sheaths primarily provide mechanical protection against damage or environmental factors, but they can also serve insulating purposes, as seen in electrical cable sheaths that shield conductors from moisture, abrasion, and electrical interference.^[15] Contextually, sheaths appear in natural settings, such as the biological myelin sheath that insulates nerve axons to facilitate rapid signal transmission, or in artificial applications engineered for tools, wiring, and medical devices. The term sheath differs from related concepts like "casing," which denotes a broader, often non-conforming enclosure for general containment, whereas a sheath implies a tailored, intimate fit.^[16] Similarly, "hull" refers to the structural outer shell of vehicles such as ships or aircraft, typically providing buoyancy or aerodynamic integrity rather than enclosing an insertable elongated element.^[17] Historically, the concept originated with literal coverings for weapons, such as medieval sword sheaths, and has since expanded to metaphorical and scientific uses, including layered protective structures in biology and engineering.^[18] This evolution reflects broader applications beyond physical blades to abstract protective layers in diverse fields.

Biological Sheaths

In Human and Animal Anatomy

In human and animal anatomy, sheaths are specialized connective tissue or cellular structures that encase and protect vital components such as blood vessels, nerves, muscles, and tendons, while also enabling efficient physiological functions like conduction, movement, and growth. These structures vary in composition—from fibrous enclosures to lipid-rich insulators—and are essential for maintaining structural integrity and reducing friction or damage in dynamic environments. Common examples include vascular, neural, and muscular sheaths found across vertebrates. The carotid sheath is a fibrous condensation of the deep cervical fascia in the neck that forms a protective enclosure around key neurovascular elements. It contains the common or internal carotid artery, the internal jugular vein, and the vagus nerve (cranial nerve X), along with portions of the sympathetic chain and lymph nodes. This sheath is bilaterally located in the carotid space and extends from the skull base to the aortic arch, providing a conduit for these structures while separating them from surrounding tissues.^[19] The myelin sheath serves as an insulating layer around the axons of neurons, enhancing the speed and efficiency of nerve impulse transmission. Composed primarily of lipids and proteins, it forms a multilayered spiral wrapping derived from the plasma membrane of glial cells: Schwann cells in the peripheral nervous system produce a single sheath per axon, while oligodendrocytes in the central nervous system myelinate multiple axons. This structure facilitates saltatory conduction, where action potentials jump between unmyelinated gaps (nodes of Ranvier), significantly increasing signal velocity compared to unmyelinated fibers. Damage to the myelin sheath, known as demyelination, underlies disorders such as multiple sclerosis, leading to impaired neural communication and symptoms like muscle weakness.^[6]^[20] Tendon sheaths, particularly synovial sheaths, are double-layered membranous structures that surround tendons in areas of high friction, such as joints. The outer fibrous layer provides mechanical strength, while the inner synovial layer secretes lubricating fluid to minimize friction and nourish the tendon during movement. In the human hand, for instance, flexor tendons in the digits are enclosed within such sheaths, allowing smooth gliding through fibro-osseous tunnels reinforced by pulley systems. Similar sheaths protect extensor tendons in limbs of various mammals, preventing wear and supporting repetitive motions essential for locomotion and manipulation. Inflammation of these sheaths, termed tenosynovitis, can impair function and is common in overuse injuries.^[21]^[22] The preputial sheath is a mucosal skin fold that covers and protects the glans penis in male mammals during its non-erectile state. In humans, it corresponds to the foreskin, a retractable layer rich in sensory nerve endings and sebaceous glands that maintains hygiene and sensitivity. In animals like horses and dogs, the sheath is more pronounced, forming a pendulous external covering that retracts during erection via protractor muscles, shielding the organ from environmental hazards and infection. This structure is homologous across mammals, evolving to facilitate reproduction while providing mechanical protection.^[23]^[24] The rectus sheath encloses the rectus abdominis muscles along the anterior abdominal wall, forming a robust aponeurotic compartment that supports posture and visceral containment. It is bilaterally composed of anterior and posterior layers derived from the aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles. Above the arcuate line (approximately midway between the umbilicus and pubis), the posterior layer includes contributions from all three muscles; below it, the posterior layer is absent, with all aponeuroses passing anteriorly. This configuration enhances abdominal strength for activities like flexion and stabilizes the linea alba, with clinical relevance in surgeries such as hernias where sheath integrity prevents protrusion.^[25] In hair follicles, the root sheath provides structural anchorage and guidance for emerging hair shafts, consisting of inner and outer components. The inner root sheath includes three layers: Henle's layer (outermost, keratinized first for rigidity), Huxley's layer (intermediate, adding thickness), and the cuticle (innermost, interlocking with the hair cuticle). The outer root sheath, continuous with the epidermis, forms a flexible epithelial sleeve that molds around the follicle bulb. These layers, produced by matrix cells during the anagen growth phase, ensure hair integrity against mechanical stress and contribute to cyclic regeneration in mammals, with disruptions linked to conditions like alopecia.^[26]^[27]

In Plant Structures

In botany, a leaf sheath refers to the basal portion of a leaf that wraps around the stem, providing structural support and protection in various plant species, particularly within the Poaceae (grass) family. In grasses, the leaf sheath encloses the culm internode, emerging from nodes and contributing to the plant's overall stability by reinforcing the stem against mechanical stress from wind or grazing.^[28]^[29] These sheaths are typically split and overlapping, allowing flexibility for growth while maintaining enclosure, in contrast to the fully closed sheaths observed in related families like Cyperaceae (sedges), where the configuration influences moisture retention around the stem base.^[30] This structure is characteristic of monocotyledonous plants in the Poaceae, aiding in the protection of vascular tissues and meristems from environmental damage. Petiole sheaths extend this concept in certain monocots, where the leaf base forms an elongated sheath that encircles the stem, enhancing mechanical stability and facilitating nutrient transport. In banana plants (Musa spp.), the leaf sheath transitions into a petiole with a hollow, U-shaped cross-section reinforced by longitudinal fibers, which supports the weight of broad leaves and channels water and nutrients through vascular bundles.^[31]^[32] Similarly, in iris species (Iris spp.), the sword-like leaves feature inwardly folded bases that sheath the rhizome or stem, providing rigidity and aiding in the distribution of absorbed nutrients from roots to aerial parts.^[33] These adaptations are crucial for upright growth in herbaceous perennials, preventing lodging and optimizing resource allocation. Leaf sheaths play key roles in plant physiology, including defense against herbivores through their tough, fibrous composition, which deters feeding by increasing mechanical resistance at the stem base.^[34] They also contribute to gas exchange regulation, as sheaths often bear stomata that facilitate daytime photosynthesis and nighttime transpiration, particularly in crops like barley where abaxial sheath stomata account for a significant portion of whole-plant CO₂ uptake and water loss.^[35] In wetland environments, some monocots exhibit inflated sheaths that enhance buoyancy, allowing plants to float and access oxygen in flooded conditions while maintaining stability.^[36] These features represent adaptive responses to habitat-specific stresses, such as waterlogging. Evolutionarily, leaf sheaths in angiosperms derive from modified leaf bases, a trait prominent in monocots and linked to the diversification of early flowering plants. Fossil evidence from the Cretaceous period, including grass-like phytoliths and leaf fragments dated to approximately 113–100 million years ago, indicates that sheath structures emerged alongside the radiation of Poaceae in the late Early Cretaceous, supporting basal growth and resilience in diverse ecosystems.^[37]^[38] This development coincided with angiosperm dominance, where sheaths facilitated efficient resource use in understory and open habitats.^[39]

Technological and Engineering Sheaths

Electrical and Protective Coverings

In electrical engineering, cable sheaths serve as the outermost protective layer for electrical wires and cables, typically constructed from materials such as polyvinyl chloride (PVC), rubber, or polyethylene to shield against moisture ingress, mechanical abrasion, and electromagnetic interference.^[15] These sheaths provide essential insulation, preventing short circuits and ensuring safe power transmission in various environments, with PVC being the most widely used due to its cost-effectiveness, flexibility, and moderate durability.^[15] Cable sheaths come in two primary types: unarmoured, which rely solely on the polymeric outer layer for protection and are suitable for indoor or low-risk installations, and armoured, which incorporate additional steel wire or tape reinforcements embedded within or over the sheath to enhance resistance to physical damage in harsh outdoor or buried applications.^[40] Polyethylene variants, including cross-linked polyethylene (XLPE), offer superior chemical resistance and longevity compared to PVC in corrosive settings.^[41] Beyond electrical cables, protective sheaths are employed in mechanical and industrial contexts, such as hydraulic hoses and pipes, where thermoplastic jackets encase the inner linings to deliver flexibility, abrasion resistance, and corrosion protection against oils, chemicals, and environmental factors.^[42] These sheaths, often made from durable PVC reinforced with helical plastic elements or nylon-based materials, safeguard conduits in machinery and fluid transfer systems, extending service life in demanding conditions like construction equipment or manufacturing lines.^[43] For instance, urethane-coated ballistic nylon sleeves provide reusable, water- and oil-resistant barriers that prevent wear from friction and external impacts.^[44] The evolution of these sheaths traces back to the mid-19th century, when gutta-percha—a natural latex derived from tree sap—emerged as the first effective insulator for submarine telegraph cables starting in the 1850s, with continued use into the 1880s and beyond, offering waterproofing and dielectric properties superior to earlier materials like India rubber.^[45]^[46] By the mid-20th century, synthetic polymers such as PVC and polyethylene supplanted gutta-percha, with widespread adoption post-1950s driven by advancements in extrusion technology and the need for scalable, cost-efficient production in expanding power grids. In recent decades, particularly post-2010, there has been a transition to halogen-free low-smoke zero-halogen (LSZH) sheaths for improved fire safety and environmental compliance, as per standards like the EU Construction Products Regulation (CPR).^[46] Modern iterations incorporate advanced polymer composites for enhanced thermal stability and UV resistance. Compliance with international standards like IEC 60227 ensures the reliability of PVC-insulated power cables, specifying requirements for sheaths in rigid and flexible designs rated up to 450/750 V, with rigorous testing for dielectric strength to withstand voltage stresses and environmental durability against aging, heat, and mechanical strain.^[47] This standard mandates insulation resistance thresholds and dielectric performance to minimize breakdown risks, facilitating safe deployment in global electrical infrastructures.^[48]

Medical and Scientific Applications

In medical procedures, introducer sheaths serve as thin, flexible tubes inserted percutaneously to provide a conduit for guiding catheters, wires, or other devices into blood vessels during catheterization, facilitating access while minimizing vessel trauma.^[49] These devices are typically sized from 4 to 24 French gauge to accommodate varying procedural needs, with smaller diameters preferred to reduce arteriotomy size and vascular risks.^[50] Common materials include polyurethane for its biocompatibility, flexibility, and kink resistance, enabling smooth insertion and device exchange.^[51] Potential complications encompass vessel perforation, dissection, and thrombosis, which can arise from prolonged indwelling or mechanical irritation, underscoring the need for careful sizing and anticoagulation protocols.^[51]^[52] In endoscopic applications, sheaths act as protective sleeves encasing the endoscope to preserve sterility during insertion and manipulation within body cavities, thereby preventing microbial contamination of the instrument and patient.^[53] These disposable or sterilizable covers also mitigate tissue trauma by providing a lubricious barrier that eases passage through narrow lumens and reduces friction against delicate mucosal surfaces.^[54] For instance, in gastrointestinal or urological endoscopy, such sheaths enable single-use protection without compromising visualization, aligning with infection control guidelines that emphasize barriers to cross-transmission.^[53] In scientific instrumentation, sheaths are employed to contain and manage biological specimens during analysis, particularly in flow cytometry where sheath fluid hydrodynamically focuses cell suspensions into a single-file stream for laser interrogation.^[55] This laminar sheath encases the sample core, stabilizing particle alignment and enabling high-throughput multiparametric assessment of cellular properties like size, granularity, and fluorescence markers in heterogeneous populations such as blood or tissue-derived cells.^[56] Similarly, in microscopy setups, protective sample sheaths safeguard delicate biological specimens from environmental contaminants during imaging, ensuring artifact-free observation of microstructures in live or fixed preparations.^[57] Advancements in sheath technology have enhanced procedural safety and efficacy since the mid-1980s, with the widespread adoption of hydrophilic coatings that activate upon hydration to create a low-friction surface, facilitating easier vessel entry and reducing endothelial damage during catheterization.^[58] These coatings, often polymer-based, have evolved to minimize particulate shedding and improve hemocompatibility, addressing early limitations in lubricity observed in uncoated designs.^[59] Introducer sheaths are regulated by the U.S. Food and Drug Administration as Class II devices, subject to special controls including performance standards for sterility, biocompatibility, and labeling to mitigate risks like infection or embolism.^[60]

Artifacts and Cultural Objects

Weapon and Tool Sheaths

A scabbard serves as a rigid or flexible protective case for swords, daggers, or bayonets, typically constructed from a wooden core clad in leather, metal, or other materials to shield the blade from damage and facilitate safe handling. Key structural features include the throat, a reinforced metal or leather fitting at the upper end that guides the blade's insertion and prevents wear, and the chape, a protective metal tip at the bottom that strengthens the point end and often includes suspension rings or hooks for attachment to belts or baldrics. These components ensure durability during transport and combat, with designs varying by era and region to balance functionality and ornamentation.^[61]^[62] Historical examples illustrate the evolution and cultural adaptation of scabbards. In Bronze Age Egypt, during the New Kingdom period (circa 1550–1070 BCE), sheaths for daggers and swords were elaborately crafted, such as the gold sheath from Tutankhamun's tomb, which features intricate inlays of semi-precious stones and symbolic motifs like protective animals, underscoring their role in royal burial rites and divine authority. In medieval Europe (circa 5th–15th centuries CE), scabbards were commonly suspended from belts via a frog—a leather loop or strap attached to the scabbard—allowing knights and soldiers to wear swords at the hip for quick access, as evidenced in surviving artifacts and period illustrations from sites like the Tower of London armory. These attachments emphasized practical mobility in battle while enabling decorative elements like embossed leather or metal mounts to denote social rank.^[63]^[64] Tool sheaths extend the scabbard concept to utilitarian implements like knives and axes, prioritizing accessibility and retention. Contemporary designs often employ leather for traditional flexibility and custom fit or Kydex, a thermoplastic material molded for precise retention and rapid deployment, as seen in tactical holsters that secure the tool at the belt while allowing one-handed quick-draw. In Japanese samurai culture, the katana's saya—a lacquered wooden scabbard—transcends mere protection, with multilayered urushi lacquer finishes in black, red, or patterned motifs signifying the wearer's status and clan affiliation, integral to the bushido code's emphasis on aesthetic harmony and martial readiness.^[65]

Clothing and Body Adornments

In fashion, the sheath dress emerged as a hallmark of mid-20th-century style, characterized by its fitted, straight silhouette that follows the body's contours from shoulder to hem without a defined waist seam.^[66] This design, popularized in the 1950s as part of Christian Dior's "New Look" revolution, emphasized slim, elegant lines through vertical darts for shaping, often crafted from luxurious natural materials like silk or wool to achieve a smooth, body-hugging fit.^[67] The garment's form-fitting nature provided both aesthetic appeal and subtle support, influencing daytime and cocktail attire across Western wardrobes. In traditional cultural contexts, the koteka serves as a prominent example of a sheath-like body adornment among indigenous Papuan men in Papua New Guinea, functioning as a penis gourd sheath worn as a garment.^[68] Constructed from a dried gourd hollowed out and secured with vines or string, the koteka has been a symbol of manhood and social status since pre-colonial times, offering practical coverage while integrating into ceremonial and daily dress. Its use persists in certain highland communities, highlighting the role of sheath elements in non-Western adornments for cultural identity and modesty. Leg sheaths, known historically as gaiters, have long provided protective coverings for the lower limbs in attire, originating in European military and equestrian contexts from the 18th century to shield against mud, debris, and weather.^[69] In contemporary sports, these evolve into compression sleeves made of elastic fabrics that wrap the calves or thighs to provide support during activities such as running or cycling. The materials used in these sheath-style adornments have transitioned from natural fibers like wool, silk, and plant-based gourds, which offered breathability but limited stretch, to modern synthetics such as spandex—introduced in 1958—for enhanced elasticity and form retention.^[70] This shift enables greater adaptability in fitted designs, supporting both functional protection and stylistic versatility across cultural and athletic applications.^[71]

Other Specialized Uses

In Physics and Astronomy

In plasma physics, the Debye sheath refers to a thin, non-neutral boundary layer that forms around charged objects immersed in a plasma, typically on the order of the Debye length thick, where ions accumulate to neutralize the excess negative charge from more mobile electrons. The Debye length, \lambda_D, is defined as \lambda_D = \sqrt{\frac{\epsilon_0 k T_e}{n_e e^2}}, where \epsilon_0 is the vacuum permittivity, k is Boltzmann's constant, T_e is the electron temperature, n_e is the electron density, and e is the elementary charge; this scale characterizes the distance over which electric fields are screened in the plasma. Within the sheath, quasi-neutrality breaks down (n_e \neq n_i), leading to an electric field that accelerates ions toward the surface while repelling electrons.^[72] The sheath potential drop arises from the need to balance electron and ion fluxes at the boundary, with the pre-sheath region—under the quasi-neutrality approximation (n_e \approx n_i)—exhibiting a potential decrease of approximately \frac{1}{2} \frac{k T_e}{e} to accelerate ions to the Bohm velocity v_B = \sqrt{\frac{k T_e}{m_i}} at the sheath edge.^[73] The full sheath drop is larger, often \phi_w - \phi_s \approx -\frac{k T_e}{e} \ln \left( \sqrt{\frac{m_i}{2\pi m_e}} \right), ensuring current balance.^[73] These sheaths are critical in controlled fusion reactors, where they mediate plasma-wall interactions and influence particle and heat fluxes to divertors, and in spacecraft propulsion, where they affect thruster performance and surface erosion in ion engines.^[72] In astrophysics, the heliosheath is the turbulent boundary region of the heliosphere, where the solar wind transitions from supersonic to subsonic speeds after encountering the termination shock, separating the inner solar system from the interstellar medium.^[74] Voyager 2 detected the termination shock crossing into the heliosheath on August 30, 2007, at approximately 84 AU from the Sun, revealing variable plasma flows, enhanced magnetic fluctuations, and elevated temperatures in this layer.^[74] Ionospheric sheaths in Earth's upper atmosphere play a key role in auroral processes by forming potential structures that accelerate electrons and ions, contributing to particle precipitation and light emissions observed in auroras, as demonstrated in laboratory simulations of auroral beams.^[75]

In Philosophy and Arts

In Vedanta philosophy, the concept of kosha refers to the five sheaths or layers that envelop the true self (Atman), as outlined in the Taittiriya Upanishad, a foundational text dating to approximately the 6th century BCE. These sheaths include the annamaya kosha (food sheath, the physical body), pranamaya kosha (vital air sheath, governing energy and breath), manomaya kosha (mind sheath, encompassing thoughts and emotions), vijnanamaya kosha (intellect sheath, involving wisdom and discernment), and anandamaya kosha (bliss sheath, the subtlest layer closest to pure consciousness).^[76] The philosophical aim is to transcend these successive layers through self-inquiry and meditation, revealing the unchanging Atman beyond material and psychological coverings, thereby attaining enlightenment.^[77] In literature, the sheath serves as a potent metaphor for concealment, protection, or sudden revelation, often symbolizing restrained power or impending action. William Shakespeare employs this imagery vividly in Romeo and Juliet (Act 5, Scene 3), where Juliet addresses the dagger as "happy dagger, / This is thy sheath; there rust, and let me die," likening her body to a protective covering that receives the blade in a moment of tragic resolve.^[78] Such metaphors extend the sheath's connotation from physical enclosure to emotional or existential barriers, emphasizing themes of release and consequence. In the realm of music, the term "sheath" appears in artistic titles evoking layered or enclosed sonic experiences within electronic genres. The 2003 album Sheath by British IDM duo LFO (Mark Bell and Gez Varley) explores ambient techno and electro themes through tracks like "Blown" and "Freak," using the title to suggest immersive, enveloping soundscapes that gradually unfold.^[79] Released by Warp Records, the album reflects early 21st-century electronic experimentation, where "sheath" metaphorically implies the containment and controlled release of rhythmic and atmospheric elements.^[80]

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Aug 28, 2023 · Grass fossil record starts in the late Early Cretaceous, with sparse records until Neogene, where it expands, showing diversification and ...
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THE EARLIEST REMAINS OF GRASSES IN THE FOSSIL RECORD
These fossils indicate a minimal time of origin for the family, are consistent with an Upper Cretaceous origin of Poaceae, and suggest that as in wind- ...
[39]
Fossil evidence for Cretaceous escalation in angiosperm leaf vein ...
We show that Early Cretaceous fossil angiosperm leaves shifted from possessing low vein densities to very high vein densities by the close of the Cretaceous.
[40]
What is The Difference Between Armoured and Unarmoured Power ...
Jul 6, 2023 · The difference between armored and unarmoured cables is that there is an extra layer of metal reinforcement, and the standard armoring methods are steel belt ...
[41]
The Difference Between Armoured and Unarmoured Cables and ...
Unarmoured cables can be categorized into types such as polyethylene, polyvinyl chloride, and cross-linked polyethylene based on the outer sheath material.
[42]
Hydraulic Hose Covers | Durable Protection for HP & UHP ... - Abdex
These hose covers are made of durable PVC with plastic helix reinforcement, are lightweight, flexible, and provide extra protection against abrasion for HP and ...<|control11|><|separator|>
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A guide to hydraulic hose sleeve - Essentra Components
Aug 8, 2024 · In this guide, we'll look at hydraulic hose protection sleeves and how to ensure hose safety, for the application itself and the people who work with it.
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https://hoseandfittingsupply.com/velcro-sleeve-p/sl.htm
[45]
FAQ: The history of electrical cables
In the 1880's the first insulated cables were insulated with gutta percha, a natural latex material produced from the sap of trees of the same name. This ...
[46]
Gutta-percha | American Experience | Official Site - PBS
Polyethylene would eventually replace gutta-percha in the insulation of underwater cables as well as most other uses, but the boiled sap of the gutta tree is ...
[47]
[PDF] IEC-60227-1-2007.pdf - iTeh Standards
This part of International Standard IEC 60227 applies to rigid and flexible cables with insulation, and sheath if any, based on polyvinyl chloride, of rated ...
[48]
A Review of the Provisions of IEC 60227 - ZIMEND
Oct 2, 2025 · Electrical Properties: Wires and cables shall have adequate dielectric strength and insulation resistance. The electrical tests for products ...
[49]
21 CFR Part 870 -- Cardiovascular Devices - eCFR
A catheter introducer is a sheath used to facilitate placing a catheter through the skin into a vein or artery. (b) Classification. Class II (performance ...
[50]
Optimal Access Sheath Hemostasis Introducer - APT Medical
Full Range of Sizes and Specifications. - Over 88 sizes from 4F-24; Sheath length variable from 7cm to 25cm. Product Codes. Radial sheath Femoral sheath. French ...Missing: material polyurethane 4-24 thrombosis
[51]
[PDF] Percutaneous Sheath Introducer Product
Warning: Practitioners must be aware of complications associated with percutaneous sheath introduction including vessel wall perforation,31 pleural and ...
[52]
Impact of sheath diameter of different sheath types on vascular ... - NIH
Aug 24, 2017 · The difference in sheath diameter had no effect on either incidence or severity of vascular complications. There was no impact on mortality either.
[53]
Disinfection of Healthcare Equipment | Infection Control - CDC
Nov 28, 2023 · These probes can be covered with a sterile sheath to reduce the level of contamination on the probe and reduce the risk for infection. However, ...Missing: sleeve trauma
[54]
Scanning fiber endoscopy with highly flexible, 1-mm catheterscopes ...
For many applications, a smaller diameter and flexible endoscope is often preferred for reducing tissue trauma and medication (sedation) to reduce ...
[55]
Flow Cytometry Guide: Principles, Applications
Fluidics system: The system consists of sheath fluid and a laminar flow that narrows down the specimen core for the movement of cells in a single stream when ...Flow Cytometry - Principles... · Flow Cytometry Instruments · Flow Cytometry Applications<|separator|>
[56]
Flow Cytometry: An Overview - PMC - NIH
Flow cytometry is a technology that provides rapid multi-parametric analysis of single cells in solution. Flow cytometers utilize lasers as light sources to ...
[57]
Immunofluorescence Flow Cytometry Technique for Enumeration of ...
The use of different sheath fluids was meant to minimize complications due to sample-sheath fluid refractive index incompatibilities (12). The FACSCalibur has ...
[58]
[PDF] Hydrophilic polymer coating - Frontiers
Jan 15, 2025 · Since the mid-1980s, hydrophilic polymer coatings have been increasingly used on a wide range of intravascular medical devices such as ...
[59]
(PDF) Particulates from hydrophilic-coated guiding sheaths ...
Jun 25, 2016 · Background: Hydrophilic coatings on arterial introducer sheaths reduce the frequency of spasm during cardiac catheterization. Moreover ...Missing: 1970s | Show results with:1970s
[60]
[PDF] Catheter Sheath Introducer (CSI) Kit - accessdata.fda.gov
Catheter Sheath Introducer Kits are Cardiovascular Diagnostic Devices and are classified as Class II devices according to 21 CFR 870.1340.
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https://todsworkshop.com/pages/glossary-of-sword-scabbard-terms
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https://fwosi.com/blogs/news/difference-between-scabbard-and-sword-sheath
[63]
Gold Dagger and Sheath of Tutankhamun - Egypt Museum
Tutankhamun's mummy was provided with two daggers encased in gold sheaths, one with an iron blade and the other with a blade of hardened gold.
[64]
Sword - Hanger and scabbard - 1830-1870 | Collection Object
The locket has a frog-stud in the form of a wolf's head. Condition on acquisition: Good, sound & complete; scabbard leather possibly a later restoration.
[65]
Katana: The Sword of the Samurai - TOKI
May 27, 2020 · Saya is typically made from lightweight lacquered wood and is often decorated with matching colors, feature finishes, or hand-painted images.
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A Simple Sheath? | fiftydresses
Aug 19, 2013 · In either case, the silhouette is straight, narrow, and fitted, “shaped to body with vertical darts”, with ease of movement facilitated by a ...
[67]
1950-1959 | Fashion History Timeline
Whether she was wearing a twinset and slacks, a poodle skirt, a sheath dress, or one of Dior's New Look styles, a woman did her best to ensure that she looked ...
[68]
[PDF] Exploring the Penis Sheath of Papua New Guinea
The penis sheath is an adornment worn by indigenous male inhabitants of the western parts of Papua. New Guinea. A prevalent amount of men wear the penis sheath ...
[69]
A Quick and Dirty History of Gaiters - Stories - Kahtoola
Jul 27, 2022 · Gaiters were first used by clergy and militaries, then by equestrians, and later by outdoor adventurers, protecting from dirt, moisture, cold ...
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The Effects of Lower Leg Compression Garments on Lower ... - NIH
We identified no evidence for a beneficial or detrimental effect of lower leg CGs on the occurrence of lower extremity sports injuries, subjective ratings of ...
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Synthetic Threads | Science History Institute
Oct 3, 2016 · Nylon, the first man-made fiber, was made from coal, water, and air. It was durable, and other synthetics like acrylic, polyester, and spandex ...
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History of LYCRA® fiber | Explore Our Timeline
LYCRA fiber was invented in 1958 by Dr. Joseph Shivers, replacing rubber in shapewear. It can stretch up to 500% and return to its original shape.
[73]
[PDF] Overview of the Physics in the Plasma Sheath - MIT OpenCourseWare
We emphasize the distinction in the potential structure between the quasi-neutral plasma, a quasi-neutral col ... not-negligible potential drop in the pre-sheath.
[74]
Langmuir Sheaths - Richard Fitzpatrick
A Langmuir sheath is a thin layer of plasma, a few Debye lengths thick, coating the inside of a vessel wall, formed by a potential barrier.
[75]
Propagation into the heliosheath of a large-scale solar wind ...
Voyager 1 crossed the TS at a distance of 94 AU from the Sun in December 2004 (Stone et al. 2005) and Voyager 2 crossed it at 84 AU in August 2007 (Richardson ...
[76]
A laboratory experiment to examine the effect of auroral beams on ...
Sep 28, 2011 · The plasma potential in the sheath around the sphere is measured using an emissive probe as the electron beam energy is varied. To observe the ...<|control11|><|separator|>
[77]
https://www.wisdomlib.org/concept/five-sheaths
[78]
Five sheaths: Significance and symbolism
Oct 22, 2025 · The Five Sheaths in Hinduism, known as koshas, denote the layers surrounding the true self (Atman), including the physical, vital, mental, ...
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What does Juliet's line, "Then I'll be brief. O happy dagger, / This is ...
Feb 10, 2009 · Juliet also metaphorically compares her body to a sheath, which is where she will thrust the dagger. Inside her body and covered with blood, the ...
[80]
Sheath - LFO | Album - AllMusic
Rating 8/10 (48) Release Date. September 23, 2003. Duration. 46:41. Genre. Electronic. Styles. Techno, IDM, Club/Dance, Acid Techno. Set Your Streaming Service. Suggest ...
[81]
Sheath | LFO - Warp Records
Sheath by LFO, released 22 September 2003 1. Blown 2. Mum-man 3. Mokeylips 4. Snot 5. Moistly 6. Unafraid To Linger 7. Sleepy Chicken 8. Freak 9.
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https://smewindia.com/indian-swords-rituals-modern-and-ancient-myths/