Protective Sheath Research Articles

Exploring the axial performance of protective sheathed rock bolts through large-scale testing

Understanding the axial load transfer mechanism of rock bolts under diverse conditions is essential for optimizing reinforcement in rock structures, advancing our comprehension of rock support, and facilitating the design of robust engineering solutions. This paper reports the outcomes of an extensive experimental investigation, focusing on the axial behavior of protective sheathed rock bolts employed in corrosive environments, assessed through pullout tests. Three distinct testing setups were designed to evaluate comprehensively the performance of these rock bolts in various scenarios. The results indicated that the failure characteristics and axial behaviors of sheathed rock bolts differ significantly from conventional counterparts. The findings revealed two primary failure modes in sheathed rock bolts: bolt rupture and slip at the grout-sheath interface, based on the testing arrangement and encapsulation length. The lack of adhesion and interlocking at the grout-sheath interface prevents shear stress at the bolt-grout interface from reaching its maximum potential strength, resulting in grout damage manifesting as circumferential cracks. This, in turn, initiates crack formation, reducing the system’s bond strength. Additionally, it causes slip at the grout-sheath interface to occur at lower pullout loads. It can be inferred that the inner surface of the plastic sheath lacks the necessary structural integrity to withstand high loads, significantly impacting bond stress distribution and failure modes. The results demonstrate that the protective sheath remains intact up to an axial displacement of 28 mm, irrespective of the testing configuration. Additionally, it was observed that the maximum bond stress at the bolt-grout interface falls within the range of 6–8.7 MPa, which is below the shear strength of the grout. Consequently, achieving failure at the bolt-grout interface is not feasible.

Sodium Hypochlorite: Optimization of Application as an Exsheathing Agent for Nematode Larvae to Minimize the Risk of Reduced Viability

Objective: Nematode larvae exsheathing is a crucial procedure employed in experimental studies such as nematode viability assays, evaluating nematodes' resistance to anthelmintics, and evaluating the efficacy of anthelmintic medications. The exsheathment procedure allows for quantifying the direct impact on larvae when the protective sheath is removed. Sodium hypochlorite (NaOCl) is a commonly used artificial exsheathment medium. However, concerns have been raised about its potential impact on the viability of exsheathed larvae. A previous study utilized Strongyloides papillosus larvae, a nematode species without a protective sheath, to investigate the effects of NaOCl on parasite viability. The findings revealed that there are specific concentration (C) and exposure-time (T) thresholds (0.3% > C > 0.2%; 10 min > T > 5 min) beyond which viability decreases, and excessive exposure can cause significant damage. The current study aims to determine the optimal concentration of NaOCl that can induce exsheathment in ensheathed-type larvae without compromising their viability. Methods: Third-stage strongylid larvae of donkey origin were utilized for this study, with chemical concentrations of 3%, 0.3%, 0.2%, 0.1%, or 0.05%. Larval motility served as the criterion for evaluating viability. Results: NaOCl can exsheath larvae at any of the five concentration levels evaluated, depending on the duration of exposure to the compound. A concentration of 0.2% is considered optimal, inducing exsheathment as early as 2 minutes. Extended exposure for up to 10 minutes did not impact larval viability. A 3% solution causes larval damage. Conclusions: Regarding the effect of NaOCl on nematode larvae, the results validate the earlier findings with Strongyloides papillosus and those by other authors employing nematodes such as Haemonchus contortus and Cooperia curticei, and the entomopathogenic nematode Heterorhabditis bacteriophora.

Inception of vented water trees in high voltage XLPE cable insulation: Effect of inorganic contaminations inside the semiconductive material

AbstractWet‐design AC subsea power cables are currently rated up to a maximum voltage of 72.5 kV. These high voltage (HV) cables are cost‐effective alternatives to subsea cables kept dry by a protective lead sheath and exhibit superior properties for dynamic applications. However, several vented water trees, degradation phenomena reducing the cable lifetime, are observed in a HV XLPE insulated cable subjected to wet aging in the laboratory. The water trees initiate from a smooth and clean XLPE insulation/semiconductive screen interface. In this paper, we show that voids in the range 15–150 μm are observed in the conductor screen, 50–320 μm from the water tree inception sites. Degradation of the semiconductive material is observed, in the form of porous regions that connect the voids to the water tree inception sites. NaCl impurities are detected on the void surfaces and in the porous regions. These features are proposed to be the pre‐requisites for the formation of the vented water trees observed in this type of cable. The mechanism responsible for the formation of the void and porous regions in the semiconductive cable screen is discussed based on the observations.

Recent Advances in Understanding and Treating Multiple Sclerosis

MS, often known as multiple sclerosis, is a chronic autoimmune illness that is characterised by inflammation, demyelination, and neurodegeneration in the central nervous system (CNS). This review provides a comprehensive summary of current achievements in multiple sclerosis (MS) research, focusing on substantial advancements in understanding the biology of the disease, improving diagnostic tools, and developing a variety of treatment strategies. Multiple Sclerosis (MS) is characterised by an attack by the immune system on myelin, which is the protective sheath that surrounds nerve fibres. This attack results in a wide variety of neurological symptoms. Genetic factors, such as polymorphisms in the HLA-DRB1 gene, as well as environmental variables, such as a lack of vitamin D and viral infections, have been identified as contributors to disease susceptibility. However, the exact cause of multiple sclerosis (MS) is still unknown. Among the advancements in diagnostics are the utilisation of more sophisticated magnetic resonance imaging (MRI) techniques and the investigation of novel biomarkers in cerebrospinal fluid (CSF) and clinical blood. Beyond the standard disease-modifying treatments (DMTs), there are now additional treatment alternatives available, which include more recent medications that have mechanisms of action that are more specifically targeted. Treatments that are only coming into existence, such as monoclonal antibodies and cell-based therapies, provide the possibility of progress in the management of diseases. The purpose of this review is to provide a summary of the most important discoveries, identify trends in research, and explore the significance of current developments for MS care as well as future research directions.

Multilevel neurium-mimetic individualized graft via additive manufacturing for efficient tissue repair

Complicated peripheral nerve injuries or defects, especially at branching sites, remain a prominent clinical challenge after the application of different treatment strategies. Current nerve grafts fail to match the expected shape and size for delicate and precise branched nerve repair on a case-by-case basis, and there is a lack of geometrical and microscale regenerative navigation. In this study, we develop a sugar painting-inspired individualized multilevel epi-/peri-/endoneurium-mimetic device (SpinMed) to customize natural cues, featuring a selectively protective outer sheath and an instructive core, to support rapid vascular reconstruction and consequent efficient neurite extension along the defect area. The biomimetic perineurium dictates host-guest crosslinking in which new vessels secrete multimerin 1 binding to the fibroin filler surface as an anchor, contributing to the biological endoneurium that promotes Schwann cell homing and remyelination. SpinMed implantation into rat sciatic nerve defects yields a satisfactory outcome in terms of structural reconstruction, with sensory and locomotive function restoration. We further customize SpinMed grafts based on anatomy and digital imaging, achieving rapid repair of the nerve trunk and branches superior to that achieved by autografts and decellularized grafts in a specific beagle nerve defect model, with reliable biosafety. Overall, this intelligent art-inspired biomimetic design offers a facile way to customize sophisticated high-performance nerve grafts and holds great potential for application in translational regenerative medicine.

Portable multi-focal visual evoked potential diagnostics for multiple sclerosis/optic neuritis patients

PurposeMultiple sclerosis (MS) is a neuro-inflammatory disease affecting the central nervous system (CNS), where the immune system targets and damages the protective myelin sheath surrounding nerve fibers, inhibiting axonal signal transmission. Demyelinating optic neuritis (ON), a common MS symptom, involves optic nerve damage. We’ve developed NeuroVEP, a portable, wireless diagnostic system that delivers visual stimuli through a smartphone in a headset and measures evoked potentials at the visual cortex from the scalp using custom electroencephalography electrodes.MethodsSubject vision is evaluated using a short 2.5-min full-field visual evoked potentials (ffVEP) test, followed by a 12.5-min multifocal VEP (mfVEP) test. The ffVEP evaluates the integrity of the visual pathway by analyzing the P100 component from each eye, while the mfVEP evaluates 36 individual regions of the visual field for abnormalities. Extensive signal processing, feature extraction methods, and machine learning algorithms were explored for analyzing the mfVEPs. Key metrics from patients’ ffVEP results were statistically evaluated against data collected from a group of subjects with normal vision. Custom visual stimuli with simulated defects were used to validate the mfVEP results which yielded 91% accuracy of classification.Results20 subjects, 10 controls and 10 with MS and/or ON were tested with the NeuroVEP device and a standard-of-care (SOC) VEP testing device which delivers only ffVEP stimuli. In 91% of the cases, the ffVEP results agreed between NeuroVEP and SOC device. Where available, the NeuroVEP mfVEP results were in good agreement with Humphrey Automated Perimetry visual field analysis. The lesion locations deduced from the mfVEP data were consistent with Magnetic Resonance Imaging and Optical Coherence Tomography findings.ConclusionThis pilot study indicates that NeuroVEP has the potential to be a reliable, portable, and objective diagnostic device for electrophysiology and visual field analysis for neuro-visual disorders.

Investigations of an Early Iron Age Siege 2

A research team of the Institute of Archaeological Sciences of the Eötvös Loránd University continued the fieldwork between 1 September 2022 and 31 December 2023 on two Early and Middle Iron Age sites, Dédestapolcsány-Verebce-bérc and Dédestapolcsány-Várerdő, in the frame of a project investigating Early Iron Age crises. New excavation trenches were opened at the fortified settlement in the north of the Bükk Mountains (Northern Hungary). One was an extension of a trench opened in 2022, where remains of a burnt house had been identified. Metal detector surveys recovered some new fascinating stray metal finds (e.g., an akinakes, battle axes, and the bronze protective sheath of a sword) and new assemblages (iron tool deposits and a hoard of gold jewellery and amber beads). Eleven more graves were excavated in the cemetery (Várerdő) north of the coeval settlement. The most interesting grave was the burial of an adult man with rich grave goods such as an ironworking toolkit, pottery, and other items.

The Impact of Cytomegalovirus Infection on Natural Killer and CD8+ T Cell Phenotype in Multiple Sclerosis.

Multiple sclerosis (MS) is a debilitating neurological disease that has been classified as an immune-mediated attack on myelin, the protective sheath of nerves. Some aspects of its pathogenesis are still unclear; nevertheless, it is generally established that viral infections influence the course of the disease. Cytomegalovirus (CMV) is a major pathogen involved in alterations of the immune system, including the expansion of highly differentiated cytotoxic CD8+ T cells and the accumulation of adaptive natural killer (NK) cells expressing high levels of the NKG2C receptor. In this study, we evaluated the impact of latent CMV infection on MS patients through the characterization of peripheral NK cells, CD8+ T cells, and NKT-like cells using flow cytometry. We evaluated the associations between immune cell profiles and clinical features such as MS duration and MS progression, evaluated using the Expanded Disability Status Scale (EDSS). We showed that NK cells, CD8+ T cells, and NKT-like cells had an altered phenotype in CMV-infected MS patients and displayed high levels of the NKG2C receptor. Moreover, in MS patients, increased NKG2C expression levels were found to be associated with higher EDSS scores. Overall, these results support the hypothesis that CMV infection imprints the immune system by modifying the phenotype and receptor repertoire of NK and CD8+ T cells, suggesting a detrimental role of CMV on MS progression.

The effect of artificial insemination catheters covered with protective sheaths on conception rates in heifers

The effect of artificial insemination catheters covered with protective sheaths on conception rates in heifers

Hybrid Peripheral Neurostimulation to Treat Chronic Post-Meningitis Headache- A Case Report

Introduction: Chronic post-meningitis headaches present clinically with persistent symptoms often mirroring migraines or tension-type headaches. These frequently include photophobia, phonophobia, and associated nausea and vomiting, similar to other primary headache disorders. Central to the pathology of viral meningitis is the inflammation of the meninges—the intricate protective sheaths encasing the brain and spinal cord. Case: This case study details a 56-year-old female patient experiencing chronic daily headaches and facial pain following an episode of self-resolving viral meningitis. Traditional therapeutic interventions failed to achieve satisfactory symptom control for the patient. In response to the treatment-resistant nature of the patient’s condition, a neurostimulator strategy was implemented providing over 95% symptom relief reported at week 12 post-implantation. This strategy employed a hybrid approach combining high cervical and occipital lead placements, with the goal of enhancing neurostimulator coverage and mitigating the patient’s persistent symptoms. Conclusion: Preliminary observations suggest a potential avenue for further research and exploration in the domain of refractory headaches. Hybrid peripheral neurostimulation, as an emerging paradigm in neuromodulation, draws from the principles of neural plasticity and targeted neuromodulation. This case serves as an exemplar for refractory post-meningitis headaches, offering an innovative solution when traditional therapies have failed to provide relief

Modified sclerotherapy needle catheter as protective sheath for laser fibre passage in channelled flexible laryngoscopes.

Modified sclerotherapy needle catheter as protective sheath for laser fibre passage in channelled flexible laryngoscopes.

A method to improve the barrier performance of flexible riser internal pressure sheath—Heat transfer experiment and simulation

AbstractA considerable amount of acidic gas penetrates into the annulus between the internal pressure sheath and the outer protective sheath during the service of flexible risers, which will inevitably lead to corrosion of the metal functional layer. Many researchers have modified nanocomposites from the mass transfer perspective to reduce the materials' permeability coefficient. While permeation is an integrated process of heat and mass transfer process, heat distribution directly impacts gas permeation. Herein, the thermal conductivity of flexible riser liner materials is predicted for the first time by a combination of molecular dynamics and experiments, and then the radial temperature distribution under different seawater temperatures and internal fluid temperatures is investigated by finite element analysis. Finally, the effect of temperature distribution on the permeation coefficient was analyzed. The results demonstrate that the thermal conductivity can be predicted by molecular dynamics simulation, and the thermal conductivity of (polyvinylidene difluoride) PVDF/TiO2 decreases, while the thermal conductivity of PVDF/carbon nanotube (CNT) increases compared with pure PVDF. The temperature distribution of the internal pressure sheath material decreases when condensate water is present. As the fluid temperature rises from 30 to 110°C, the maximum increase ratio in the permeability of PVDF/CNT over PVDF increased from 3.6% to 14.8%, and the maximum decrease ratio of PVDF/TiO2 permeability coefficient compared with PVDF is from 1.2% to 4.6%. The results present a new idea to improve the barrier properties of materials by decreasing thermal conductivity.

Artificial axons as a biomimetic 3D myelination platform for the discovery and validation of promyelinating compounds

Multiple sclerosis (MS), a chronic neurodegenerative disease driven by damage to the protective myelin sheath, is currently incurable. Today, all clinically available treatments modulate the immune-mediated symptoms of the disease but they fail to stop neurodegeneration in many patients. Remyelination, the regenerative process of myelin repair by oligodendrocytes, which is considered a necessary step to protect demyelinated axons and stop neuronal death, is impaired in MS patients. One of the major obstacles to finding effective remyelinating drugs is the lack of biomimetic drug screening platforms that enable quantification of compounds’ potential to stimulate 3D myelination in the physiologically relevant axon-like environment. To address this need, we built a unique myelination drug discovery platform, by expanding our previously developed technology, artificial axons (AAs), which enables 3D-printing of synthetic axon mimics with the geometry and mechanical properties closely resembling those of biological axons. This platform allows for high-throughput phenotypic myelination assay based on quantification of 3D wrapping of myelin membrane around axons in response to compounds. Here, we demonstrate quantification of 3D myelin wrapping by rat oligodendrocytes around the axon mimics in response to a small library of known pro-myelinating compounds. This assay shows pro-myelinating activity for all tested compounds consistent with the published in vitro and in vivo data, demonstrating predictive power of AA platform. We find that stimulation of myelin wrapping by these compounds is dose-dependent, providing a facile means to quantify the compounds’ potency and efficacy in promoting myelin wrapping. Further, the ranking of relative efficacy among these compounds differs in this 3D axon-like environment as compared to a traditional oligodendrocyte 2D differentiation assay quantifying area of deposited myelin membrane. Together, we demonstrate that the artificial axons platform and associated phenotypic myelin wrapping assay afford direct evaluation of myelin wrapping by oligodendrocytes in response to soluble compounds in an axon-like environment, providing a predictive tool for the discovery of remyelinating therapies.

Stretchable and Self-Healable Fiber-Shaped Conductors Suitable for Harsh Environments.

Fiber-shaped conductors with high electrical conductivity, stretchability, and durability have attracted increasing attention due to their potential for integration into arbitrary wearable forms. However, these fiber conductors still suffer from low reliability and short life span, particularly in harsh environments. Herein, a conductive, environment-tolerant, stretchable, and healable fiber conductor (CESH), which consists of a self-healable and stretchable organohydrogel fiber core, a conductive and buckled silver nanowire coating, and a self-healable and waterproof protective sheath, is reported. Such a multilayer core-sheath design not only offers high stretchability (≈2400%), high electrical conductivity (1.0 × 106 S m-1 ), outstanding self-healing ability and durability, but also possesses unprecedented tolerance in harsh environments including wide working temperature (-60-20 °C), arid (≈10 % RH (RH: room humidity)), and underwater conditions. As proof-of-concept demonstrations, CESHs are integrated into various wearable formats as interconnectors to steadily perform the electric function under different mechanical deformations and harsh conditions. Such a new type of multifunctional fiber conductors can bridge the gap in stretchable and self-healing fiber technologies by providing ultrastable electrical conductance and excellent environmental tolerance, which can greatly expand the range of applications for fiber conductors.

Alterations of Oligodendrocyte and Myelin Energy Metabolism in Multiple Sclerosis.

Multiple sclerosis (MS) is a complex autoimmune disease of the central nervous system (CNS), characterized by demyelination and neurodegeneration. Oligodendrocytes play a vital role in maintaining the integrity of myelin, the protective sheath around nerve fibres essential for efficient signal transmission. However, in MS, oligodendrocytes become dysfunctional, leading to myelin damage and axonal degeneration. Emerging evidence suggests that metabolic changes, including mitochondrial dysfunction and alterations in glucose and lipid metabolism, contribute significantly to the pathogenesis of MS. Mitochondrial dysfunction is observed in both immune cells and oligodendrocytes within the CNS of MS patients. Impaired mitochondrial function leads to energy deficits, affecting crucial processes such as impulse transmission and axonal transport, ultimately contributing to neurodegeneration. Moreover, mitochondrial dysfunction is linked to the generation of reactive oxygen species (ROS), exacerbating myelin damage and inflammation. Altered glucose metabolism affects the energy supply required for oligodendrocyte function and myelin synthesis. Dysregulated lipid metabolism results in changes to the composition of myelin, affecting its stability and integrity. Importantly, low levels of polyunsaturated fatty acids in MS are associated with upregulated lipid metabolism and enhanced glucose catabolism. Understanding the intricate relationship between these mechanisms is crucial for developing targeted therapies to preserve myelin and promote neurological recovery in individuals with MS. Addressing these metabolic aspects may offer new insights into potential therapeutic strategies to halt disease progression and improve the quality of life for MS patients.

PmPD@Fungi-derived monolithic carbon sponge as a high-capacity carbon electrode for desalination in flow-through capacitive deionization

Flow-through capacitive deionization (FT-CDI) is a promising technology for desalination due to its large-scale applicability and cost-effectiveness. However, binder-free monolithic carbon sponge (MCS) electrodes with robust structures, preferable permeability, and rapid electron transfer rate are desired to achieve high desalination performance. Herein, we developed a three-dimensional poly(m-phenylenediamine)@Fungi (PmPD@Fungi)-derived MCS (PMCS) by a simple strategy. The PmPD@Fungi monolithic sponge precursor was constructed using the cross-linked structure of fungi hypha as the skeleton based on its high aspect ratio. The NH2-rich PmPD layer served as a protective sheath and nitrogen source to be wrapped on the fungi surface by in situ polymerization. PMCS shows a superb CDI performance with an ion (Cl-) removal capacity of 11.82 mg g−1 due to its high-nitrogen content and optimized surface area, increasing by 162 % more than fungi-derived MCS (FMCS). Compared with FMCS, the electrical conductivity and compressive strength of PMCS were improved by 90 % and 27 %, respectively. The prepared PMCS electrode provides a promising alternative for FT-CDI towards future desalination technologies.

The Roth Net at 40 years: celebrating the spirit of innovation

The Roth Net at 40 years: celebrating the spirit of innovation

TEMPERATURE DEPENDENCE OF HEAT CAPACITY AND CHANGES IN THERMODYNAMIC FUNCTIONS OF ALLOYS OF THE Pb – Te SYSTEM

Lead, in comparison with other metals, has low chemical activity and high corrosion resistance. Complex alloying of lead with antimony, tellurium and copper in optimal concentrations made it possible to obtain highly effective alloys for protective cable sheaths. Pb – Sb – Cu – Te lead alloy provides the cable sheath with high resistance to fatigue, creep and active deformation in a wide temperature range, as well as good manufacturability. The basis for such a complex of positive characteristics is a specific fine-grained thermostable structure, which determines the stability of properties in operation. Alloys of this composition are at the level of world standards: they have the best complex of operational and technological characteristics compared to the most promising domestic and foreign analogues. In the work, the heat capacity of the alloys of the Rb – Te system was determined in the "cooling" mode by the known heat capacity of a reference sample made of copper grade M00. Polynomials describing the temperature dependence of the heat capacity and changes in the thermodynamic functions of alloys are obtained. It isfound that with increasing temperature and tellurium content, the heat capacity, enthalpy and entropy of lead increase slightly, and the Gibbs energy values decrease.

An update on oral peripheral nerve sheath tumors.

Peripheral nerve sheath tumors (PNSTs) are defined as type of sarcomas that develops in cells which forms a protective sheath (covering) around the peripheral nerve, i.e., the cells of myelin sheath. Nerve tumors are of neuroectodermal in origin as it was composed of small rounded ectodermal cells that affect exclusively soft tissues. PNSTs are most common neoplasm with classic clinicopathological features, but they are diagnostically challenging. They consist of wide spectrum of tumors ranging from benign tumors to malignant nerve sheath tumors and its prevalent in oral tissues. Diagnosis of PNSTs are quite hectic but made possible by histopathology and immunohistological markers.

Interface interaction-mediated design of tough and conductive MXene-composited polymer hydrogel with high stretchability and low hysteresis for high-performance multiple sensing

Conductive hydrogels based on two-dimensional (2D) nanomaterials, MXene, have emerged as promising materials for flexible wearable sensors. In these applications, the integration of high toughness, ultrastretchability, low hysteresis, self-adhesiveness, and multiple sensory functions into one gel is essential. However, serious issues, such as easy restacking and inevitable oxidation of MXene nanosheets in aqueous media and weak interfacial bindings between MXene and the gel network, make it almost impossible to achieve the multiple performances mentioned above. Here we present a conductive MXene-composited polymer (MCP) hydrogel by incorporating gelatin-modified MXene into polyacrylamide (PAAm) hydrogel for the fabrication of multifunctional sensors. The presence of gelatin not only greatly improves the stability of the MXene nanosheets by forming a protective sheath, but also largely enhances the interfacial interactions between the MXene and the hydrogel network as molecular glues. Thus, the MCP hydrogel exhibits a high strength (430 kPa), remarkable stretchability (1100%), low hysteresis (<10% at 500% cyclic tensile), and excellent repeatable adhesion. The resultant MCP hydrogel-based versatile sensors display a high strain sensitivity with a broad working range (gauge factor (GF) = 8.83, up to 1000%), realizing the detection of various human motions. Moreover, the prepared sensors possess superior thermosensitive capacities (1.110/°C) for the measurement of body temperature. This strategy opens horizons to designing high-performance MXene-based hydrogels for advanced sensing platforms.