183 research outputs found

    Unconventional Metallic Magnetism: Non-analyticity and Sign-changing Behavior of Orbital Magnetization in ABC Trilayer Graphene

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    We study an unique form of metallic ferromagnetism in which orbital moments surpasses the role of spin moments in shaping the overall magnetization. This system emerges naturally upon doping a topologically non-trivial Chern band in the recently identified quarter metal phase of rhombohedral trilayer graphene. Our comprehensive scan of the density-interlayer potential parameter space reveals an unexpected landscape of orbital magnetization marked by two sign changes and a line of singularities. The sign change originates from an intense Berry curvature concentrated close to the band-edge, and the singularity arises from a topological Lifshitz transition that transform a simply connected Fermi sea into an annular Fermi sea. Importantly, these variations occur while the groundstate order-parameter (i.e.~valley and spin polarization) remains unchanged. This unconventional relationship between the order parameter and magnetization markedly contrasts traditional spin ferromagnets, where spin magnetization is simply proportional to the groundstate spin polarization via the gyromagnetic ratio. We compute energy and magnetization curves as functions of collective valley rotation to shed light on magnetization dynamics and to expand the Stoner-Wohlfarth magnetization reversal model. We provide predictions on the magnetic coercive field that can be readily tested in experiments. Our results challenge established perceptions of magnetism, emphasising the important role of orbital moments in two-dimensional materials such as graphene and transition metal dichalcogenides, and in turn, expand our understanding and potential manipulation of magnetic behaviors in these systems.Comment: 4+8 page

    Method of co-culturing mammalian muscle cells and motoneurons

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    The invention provides a method of co-culturing mammalian muscle cells and mammalian motoneurons. The method comprises preparing one or more carriers coated with a covalently bonded monolayer of trimethoxysilylpropyl diethylenetriamine (DETA); suspending isolated fetal mammalian skeletal muscle cells in serum-free medium according to medium composition 1; suspending isolated fetal mammalian spinal motoneurons in serum-free medium according to medium composition 1; plating the suspended muscle cells onto the one or more carriers at a predetermined density and allowing the muscle cells to attach; plating the suspended motoneurons at a predetermined density onto the one or more carriers and allowing the motoneurons to attach; covering the one or more carriers with a mixture of medium composition 1 and medium composition 2; and incubating the carriers covered in the media mixture

    Tissue Engineering The Motoneuron To Muscle Segment Of The Stretch Reflex Arc Circuit Utilizing Micro-fabrication, Interface Design And Defined Medium Formulation

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    The stretch reflex circuit is one of the most primitive circuits of mammalian system and serves mainly to control the length of the muscle. It consists of four elements: the stretch sensor (muscle spindle/ intrafusal fiber lie parallel between extrafusal, contractile musculature), extrafusal muscle fiber, sensory neuron and motoneuron. The basic principle of the stretch reflex arc circuit is as follows: whenever there is a sudden stretch in a muscle, it needs to compensate back to its original length so as to prevent any kind of injury. It performs this compensation process using a simple negative feed back circuit called the stretch reflex arc. Any form of stretch in a muscle activates the stretch sensors (muscle spindle/ intrafusal fiber) lying deep in each muscle. After the stretch sensors get activated, it sends a train of signals to the spinal cord through the sensory neurons. The sensory neurons relay this information to the motoneuron. The motoneuron performs the necessary information processing and sends the message to the extrafusal fibers so as to compensate for the sudden stretch action. The motoneuron conveys this message to the extrafusal fibers by communicating through the special synaptic junctions called neuromuscular junctions. Based on this information, the extrafusal fibers act accordingly so as to counter the effect of sudden stretch. This is also called the monosynaptic stretch reflex that involves a single synapse between a sensory neuron and a motoneuron. To date studying these stretch reflex circuits is only feasible in animal models. Almost no effort has been made to tissue engineer such circuits for a better understanding of the complex development and repair processes of the stretch reflex circuit formation. The long-term goal of this research is to tissue engineer a cellular prototype of the entire iii stretch reflex circuit. The specific theme of this dissertation research was to tissue engineer the motoneuron to muscle segment of the stretch reflex arc circuit utilizing micro-fabrication, interface design and defined medium formulations. In order to address this central theme, the following hypothesis has been proposed. The first part of the hypothesis is that microfabrication technology, interface design and defined medium formulations can be effectively combined to tissue engineer the motoneuron to muscle segment of the stretch reflex arc. The second part of the hypothesis is that different growth factors, hormones, nanoparticles, neurotransmitters and synthetic substrate can be optimally utilized to regenerate the adult mammalian spinal cord neurons so as to replace the embryonic motoneurons in the stretch reflex tissue engineered construct with adult motoneurons. In this body of work, the different tissue engineering strategies and technologies have been addressed to enable the recreation of a in vitro cellular prototype of the stretch reflex circuit with special emphasis on building the motoneuron to muscle segment of the circuit. In order to recreate the motoneuron to muscle segment of the stretch reflex arc, a successful methodology to tissue engineer skeletal muscle and motoneuron was essential. Hence the recreation of the motoneuron to muscle segment of the stretch reflex circuit was achieved in two parts. In the part 1 (Chapters 2-5), the challenges in skeletal muscle tissue engineering were examined. In part 2 (Chapters 6-7), apart from tissue engineering the motoneuron to muscle segment, the real time synaptic activity between motoneuron and muscle segment were studied using extensive video recordings. In part 3 (Chapters 8-10), an innovative attempt had been made to tissue engineer the adult mammalian spinal cord neurons so that in future this technology could utilized to replace the iv embryonic neurons used in the stretch reflex circuit with adult neurons. The advantage of using adult neurons is that it provides a powerful tool to study older neurons since these neurons are more prone to age related changes, neurodegenerative disorders and injuries. This study has successfully demonstrated the recreation of the motoneuron to muscle segment of the stretch reflex arc and further demonstrated the successful tissue engineering strategies to grow adult mammalian spinal cord neurons. The different cell culture technologies developed in these studies could be used as powerful tools in nerve-muscle tissue engineering, neuro-prosthetic devices and in regenerative medicine

    Unitary connections on Bratteli diagrams

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    In this paper, we extend Ocneanu's theory of connections on graphs to define a 2-category whose 0-cells are tracial Bratteli diagrams, and whose 1-cells are generalizations of unitary connections. We show that this 2-category admits an embedding into the 2-category of hyperfinite von Neumann algebras, generalizing fundamental results from subfactor theory to a 2-categorical setting.Comment: 35 page

    Sustainable nano-interventions to enhance crop yield, anthocyanin content, and marketability of onion (Allium cepa)

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    Introduction: Agriculture predominantly follows three farming systems: natural, organic (organic manures for soil nutrition), and agrochemical intensive. Agrochemical-intensive farming uses synthetic fertilizers, insecticides, pesticides, and weedicides. It holds the most prominent place in the modern agriculture business. Humankind realizes that over-reliance on synthetic agrochemicals has resulted in the declining health of the ecosystem’s soil, water, and living species. It must explore strategies to reduce synthetic agrochemicals without compromising agricultural production to restore the ecological balance. Nano-formulations help lower dosages of agrochemicals, leading to the emergence of nano-agriculture. However, the critical challenge is how we could exploit nanomaterials’ power to selectively improve crop plants’ metabolic performance so that it has a better competitive edge in the field to withstand the nutrient-seeking pressure exerted by other plants.Methods: Here we have achieved the same by root treatment of the onion crop and then growing them in the presence of organic goat manure.Results: In a 2 years field trial with onion crops, we report an increase in yield through root treatment with nano-pyrite (FeS2) plus soil application of goat dropping (Test) as compared to the use of goat dropping alone (Control). In the first-year field trial (November 2018- April 2019), the total biomass (bulb + leaf) weight of the test sample was 4.75 kg (n = 86), while control samples weighed 3.5 kg (n = 83). The total bulb weight for the control and test was 2.6 and 3.6 kg, respectively. In the second-year field trial (December 2019- April 2020), the total biomass of the test sample was 2.65 kg (n = 64), while control samples weighed 2.30 kg (n = 64). We observed a yield-boosting effect of root treatment with nano-pyrite plus soil application of goat dropping in onion crops. As monitored by spectroscopic absorbance, there is a significant increase in the anthocyanin content in test bulbs (0.069) compared to control bulbs (0.02). Similarly, the relative flavanol content in test leaves (0.253) was significantly higher compared to the control samples (0.086). We have integrated nano-agriculture and organic farming, resulting in a hybrid form; nano-organic farming bolsters the metabolic fitness of the onion (Allium cepa) to achieve sustainable food production

    Direct patterning of coplanar polyethylene glycol alkylsilane monolayers by deep-ultraviolet photolithography as a general method for high fidelity, long-term cell patterning and culture

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    This manuscript details a general method for patterning coplanar alkylsilane monolayers using deep-ultraviolet photolithography that has broad application for high fidelity patterning of cells of varying phenotype in long-term cultures. A polyethylene glycol monolayer was formed on a silica substrate and then patterned using 193 nm light from an ArF excimer laser. The regions of photoablation were then rederivatized with (3-trimethoxysilyl propyl) diethyltriamine (DETA), yielding high contrast cytophilic islands that promoted cell adhesion and growth. Rat hippocampal neurons, motoneurons, and myoblasts were then cultured in a defined, serum-free medium on the patterned surfaces for periods in excess of 40 days. This approach has been shown to be useful as a general method for the long-term culture of multiple cell types in highly defined spatial patterns and can be used for supporting complex cocultures for creating in vitro models for biological systems

    Ultrasound guided platelet rich plasma or corticosteroid for supraspinatus tendonosis or partial tear: an observational study of clinical outcome

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    Background: The clinical application of platelet rich plasma (PRP) in rotator cuff tears has increased recently. Many studies have found no difference between placebo controls and PRP and corticosteroids (CS) and some have found more rapid benefits with PRP injections. The present study was undertaken with the objectives to observe and assess efficacies of the two different treatment modalities in terms of symptomatic relief and recovery of ROM and to ascertain the duration of symptom free period and functional improvement on follow up. Methods: Observational clinical outcome study, conducted at a tertiary care hospital between September 2020 and March 2022 after institute ethical committee clearance. A total of 100 patients, with a positive clinical test for supraspinatus and magnetic resonance imaging (MRI) suggestive of supraspinatus tendinitis were divided to 2 groups and based on whether they received either intra-articular CS or PRP injection under ultrasonography (USG) guidance All patients were followed up at for assessing the outcomes at 6 weeks, 3 months and 6 months from intervention Results: The clinical outcome of the group receiving the PRP was better than group receiving CS intervention. Conclusions: PRP should therefore be considered as a viable option to treat supraspinatus tendinopathy/partial tear as it is cheap, readily available modality using patients own blood which is more acceptable to patient and also safe to individual where complications related to corticosteroids anticipated. Ultrasound guided procedure were found to enhance the accuracy of injection

    Osteological morphometric analysis of instrumentation safe zones of C1 and C2 vertebra in North Indian population: a multicentric study

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    Background: The complex anatomy and critical functional role of the C1 and C2 vertebrae necessitate precise understanding of safe zones for instrumentation to mitigate risks during surgical interventions. This study aimed to conduct a comprehensive morphometric analysis to identify and characterize safe zones for instrumentation within C1 and C2 vertebrae. Though there are multiple radiological based studies, actual osteological measurements are not available for North Indian population. Methods: 200 atlas and axis vertebrae were measured within an accuracy of 0.01 mm to ascertain various dimensions, distances and angles to guide safe exposure and instrumentation. To the best of our knowledge this observational morphometric study is first to provide actual osteological measurements in large number of C1 and C2 vertebrae in North Indian population. Results: The morphometric analysis revealed precise measurements of pedicle dimensions, transverse foramen parameters, and distances from key anatomical landmarks within C1 and C2 vertebrae. Safe zones for instrumentation were identified based on these measurements, considering the optimal implant size and trajectory to minimize the risk of neural or vascular damage. Differences between the morphology of North Indian, South Indian and Turkish C1 and C2 morphology was also identified. Conclusions: This study provides critical insights into the morphometric parameters which can be used to identify safe zones for instrumentation within the C1 and C2 vertebrae. The identified safe zones and associated measurements are essential for optimizing surgical strategies, enhancing instrumentation accuracy, and ultimately improving patient outcomes during craniovertebral surgical procedures. Spine Surgeons can utilize this data to tailor surgical approaches and implant placements, promoting safer and more effective interventions in the challenging anatomical region of the craniovertebral junction

    Chronic Draining Ear and Cholesteatoma Recidivism: A Retrospection from Clinical, Imaging, and Surgical Perspectives

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    Objective:To evaluate the reasons for persistent draining ear and cholesteatoma recidivism following canal wall down (CWD) tympanomastoidectomy by studying the sensitivity of high-resolution computed tomography (HRCT) scanning in different potential etiologies, corroborating through appropriate surgical intervention, and thereby, to suggest proper preventive measures.Methods:In this observational study, 32 chronic, refractory draining ears were subjected to revision surgery following a radical or a modified radical mastoidectomy. Besides disease (cholesteatoma/granulations) eradication, pitfalls of the primary surgeries were addressed. Data were interpreted for studying the epidemiologic profile, the clinical presentation at recurrence, the type of primary surgery, the sites of recidivism, the probable causes, and the best possible management at revision.Results:Of the 32 patients/ears, 23 had residual/recurrent cholesteatoma. Major reasons were inadequate disease clearance, contracted/inadequate conchomeatoplasty, no cavity obliteration, and inappropriate bone work. HRCT predicted persistent bridge and lateral semicircular canal dehiscence with 100%, and ossicular integrity and bony overhang with >80% sensitivity. Sinus tympani and oval window niche were the commonest sites of recurrence. At revision, radical/modified radical mastoidectomies were associated with cavity obliteration and appropriate revision of conchomeatoplasty in 28 patients.Conclusion:Recurrence of cholesteatoma/granulations is an important cause for chronic drainage from post-CWD cavities. Revision surgery explores the surgical pitfalls, and ensures clearance of disease from hidden areas, adequate bone work, and optimum conchomeatoplasty following cavity obliteration to provide a safe, dry ear with hearing improvement whenever feasible
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