Brittle superconducting magnets: an equivilent strain model

To exceed fields of 10 T in accelerator magnets, brittle superconductors like A15 Nb{sub 3}Sn and Nb{sub 3}Al or ceramic High Temperature Superconductors have to be used. For such brittle superconductors it is not their maximum tensile yield stress that limits their structural resistance as much as strain values that provoke deformations in their delicate lattice, which in turn affect their superconducting properties. Work on the sensitivity of Nb{sub 3}Sn cables to strain has been conducted in a number of stress states, including uniaxial and multi-axial, producing usually different results. This has made the need of a constituent design criterion imperative for magnet builders. In conventional structural problems an equivalent stress model is typically used to verify mechanical soundness. In the superconducting community a simple scalar equivalent strain to be used in place of an equivalent stress would be an extremely useful tool. As is well known in fundamental mechanics, there is not one single way to reduce a multiaxial strain state as represented by a 2nd order tensor to a scalar. The conceptual experiment proposed here will help determine the best scalar representation to use in the identification of an equivalent strain model

The effect of local steroid injection on prevertebral soft tissue swelling after anterior cervical discectomy and fusion

BACKGROUND AND OBJECTIVE: Airway obstruction is a lethal complication of anterior cervical discectomy and prevertebral soft tissue swelling after surgery is one the important causes of this complication. The aim of this study is to investigate the effect of local steroid injection on prevertebral soft tissue swelling after anterior cervical discectomy and fusion (ACDF). METHODS: This randomized clinical trial was conducted on 40 patients hospitalized in Qazvin educational & clinical Rajaee hospital who were candidates for ACDF in one to three segments because of myelopathy or radiculopathy. Patients were randomly divided into case and control groups. In case group (20 patients), 80 mg methylprednisolone was injected locally on the site of the operation. No injection was performed in control group (20 patients). Lateral neck radiography was performed one day before surgery and on the second and tenth day after surgery. The ratio of prevertebral soft tissue thickness to mid anteroposterior vertebral body (S/V) was calculated for C3-C7. In addition, pain and dysphagia after surgery were recorded on the second and tenth day after surgery (IRCT:201507212327N1). FINDINGS: S/V ratio in C3-C7 revealed no significant difference in both groups. On the second day after surgery, increase in S/V ratio in all cervical vertebrae revealed a significant difference between the two groups compared with the day before surgery (p<0.001). However, this level of increase on the tenth day was only significant in C5 (control group=0.10±0.07, case group=0.02±0.08) and C7 (control group=0.11±0.05, case group=0.02±0.1) (p=0.004 and p=0.002, respectively). There was also a significant difference between the two groups on the second and tenth day regarding intensity of pain and dysphagia after surgery (p=0.001). CONCLUSION: Based on the results of this study, local methylprednisolone injection reduces prevertebral soft tissue swelling, pain and dysphagia after surgery. © 2016, Babol University of Medical Sciences. All rights reserved

Development and Test of a Large-aperture Nb3Sn Cos-theta Dipole Coil with Stress Management

The design concept of the Electron Ion Collider (EIC), which is under construction at BNL, considers adding a 2nd Interaction Region (IR) and detector to the machine after completion of the present EIC project. Recent progress with development and fabrication of large-aperture high-field magnets based on the Nb3Sn technology for the HL-LHC makes this technology interesting for the 2nd EIC IR. This paper summarizes the results of feasibility studies of large-aperture high-field Nb3Sn dipoles and quadrupoles for the 2nd EIC IR.Comment: IPAC 2023. arXiv admin note: text overlap with arXiv:2304.1315

Linear and profilometric changes of the mucosa following soft tissue augmentation in the zone of aesthetic priority:A systematic review and meta-analysis

OBJECTIVES: To assess the outcomes of soft tissue augmentation, in terms of change in level and thickness of mid-buccal mucosa, at implants sites in the zone of the aesthetic priority. MATERIAL AND METHODS: MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials databases were searched (last search on 1 June 2020). Inclusion criteria were studies reporting outcomes of different materials and timing of grafting in patients undergoing soft tissue augmentation at implant sites in the aesthetic zone with a follow-up of ≥1 year after implant placement. Outcome measures assessed included changes in level and thickness of mid-buccal mucosa, implant survival, peri-implant health and patients' satisfaction. RESULTS: Eighteen out of 2,185 articles fulfilled the inclusion criteria. Meta-analysis revealed a significant difference in vertical mid-buccal soft tissue change (0.34 mm, 95% CI: 0.13-0.56, p = .002) and mid-buccal mucosa thickness (0.66 mm, 95% CI: 0.35-0.97, p < .001) following immediate implant placement in favour of the use of a graft versus no graft. Mean difference in mid-buccal mucosa level following delayed implant placement (0.17 mm, 95% CI: 0.01-0.34, p = .042) was also in favour of the use of a graft versus no graft. With regard to mucosa thickness, the use of a graft was not in favour compared with no graft following delayed implant placement (0.22 mm, 95% CI: -0.04-0.47, p = .095). Observed changes remained stable in the medium term. CONCLUSION: Soft tissue augmentation in the zone of the aesthetic priority results in less recession and a thicker mid-buccal mucosa following immediate implant placement and less recession in mid-buccal mucosa following delayed implant placement compared with no graft

Nb3AlNb_{3}Al prototype conductor for the transmission line magnet

The Very Large Hadron Collider (VLHC), under consideration for construction at Fermilab in the next 1-2 decades, is a 100 TeV cm pp collider. A major cost driver is the magnet. R&D is underway on several possible magnet designs. A low-field (2T) superferric magnet, sometimes called a transmission line magnet, may be the most cost- effective route to the VLHC. Although NbTi is now the cheapest superconductor measured in cost/kA-meter, Nb/sub 3/Al has the potential advantage that it remains superconducting at higher temperature. It may be particularly suited to the single "turn" and long straight lengths of the transmission line design. The combination of the simple magnet design and the higher strain tolerance than e.g. Nb/sub 3/Sn allows a simple process of cable fabrication, reaction, and magnet assembly. This higher strain tolerance is an advantage for splicing in the field. Sumitomo Electric Industries is producing an Nb/sub 3/Al conductor for the Fermilab low-field magnet program. (9 refs)

Jagged2 controls the generation of motor neuron and oligodendrocyte progenitors in the ventral spinal cord

In the developing spinal cord, motor neurons (MNs) and oligodendrocytes arise sequentially from a common pool of progenitors. However, the genetic network responsible for this neurogenesis to gliogenesis switch is largely unknown. A transcriptome analysis identified the Notch ligand Jagged2 (JAG2) as a Sonic hedgehog-regulated factor transiently expressed in MN progenitors (pMNs). In vivo loss- and gain-of-function experiments show that JAG2 schedules the differentiation of the pMN progenitors. At early developmental stages, Olig2 expressing pMN progenitors that enter the differentiation pathway exclusively generate MNs. At these times, the activation of the Notch pathway by JAG2 maintains selected pMN progenitors in an undifferentiated state by two mechanisms; first it inhibits MN generation by reducing Olig2 proteins levels, and second it directly inhibits the premature generation of oligodendrocyte progenitors (OLPs) by maintaining high levels of Hes5. Later, extinction of JAG2 from the pMN results in the loss of Hes5 expression, heralding the gliogenic phase of pMN progenitors. Strikingly, downregulation of JAG2 in pMN progenitors is sufficient to promote the precocious generation of OLPs. Together these data provide evidence that JAG2 is a key regulator of the timely and ordered generation of two of the defining cell types in the spinal cord, MNs and OLPs

Efficacy and morbidity of biodegradable versus titanium osteosyntheses in orthognathic surgery:A systematic review with meta-analysis and trial sequential analysis

Titanium osteosynthesis is currently the gold standard in orthognathic surgery. Use of biodegradable osteosyntheses avoids removal of plates/screws in a second operation. This systematic review aimed to assess the efficacy and morbidity of biodegradable vs. titanium osteosyntheses in orthognathic surgery (PROSPERO CRD42018086477). Patients with syndromic disorder(s) and/or cleft lip/palate were excluded. Randomised, prospective and retrospective controlled studies were searched for in nine databases (February 2021). The time periods perioperative, short‐term, intermediate, long‐term, and overall follow‐up were studied. Meta‐analyses were performed using random‐effects models. A total of 9073 records was assessed, of which 33 were included, comprising 2551 patients. Seven RCTs had ‘some concerns’ while another seven RCTs had ‘high’ risk of bias (Cochrane‐RoB2). No differences in malunion (qualitative analyses), mobility of bone segments [RR 1.37 (0.47; 3.99)], and malocclusion [RR 0.93 (0.39; 2.26)] were found. The operative time was longer in the biodegradable group [SMD 0.50 (0.09; 0.91)]. Symptomatic plate/screw removal was comparable among both groups [RR 1.29 (0.68; 2.44)]. Skeletal stability was similar in most types of surgery. Biodegradable osteosyntheses is a valid alternative to titanium osteosyntheses for orthognathic surgery, but with longer operation times. Since the quality of evidence varied from very low to moderate, high‐quality research is necessary to elucidate the potential of biodegradable osteosyntheses

Comparison of the mechanical properties of biodegradable and titanium osteosynthesis systems used in oral and maxillofacial surgery

To guide the selection of osteosynthesis systems, this study compared the mechanical properties of biodegradable and titanium osteosynthesis systems. SonicPins Rx and xG were subjected to pull-out tests. Additionally, 15 biodegradable (Inion CPS 2.0 and 2.5 mm; LactoSorb 2.0 mm; Macropore 2.0 mm; Polymax 2.0 mm; BioSorb FX 2.0 mm; ResorbX 2.1 mm; Osteotrans-MX 2.0 mm with plate thicknesses 1.0 and 1.4 mm; SonicWeld Rxplate/Rxpins, xGplate/Rxpins and xGplate/xGpins 2.1 mm without and with tapping the burr hole) and six titanium (CrossDrive (2006), CrossDrive (2018), MaxDrive; all 1.5 and 2.0 mm) straight, four-hole osteosynthesis systems were evaluated. All systems were subjected to tensile, bending and torsion tests. Pull-out loads of the SonicPins were comparable (P = 0.423). Titanium systems’ tensile loads were higher than biodegradable systems (P < 0.001). CrossDrive (2018) and MaxDrive systems’ tensile and torsional stiffness were lower, accompanied with higher ductility, than corresponding CrossDrive (2006) systems (P < 0.001). Bending stiffness of 1.5 mm titanium systems was comparable to, and of the 2.0 mm systems higher than, all biodegradable systems (P < 0.001). Regarding biodegradable systems, Inion CPS 2.5 mm had highest tensile load and torsional stiffness, SonicWeld 2.1 mm highest tensile stiffness, and BioSorbFX 2.0 mm highest bending stiffness (P < 0.001). On the basis of the results of this study, the CrossDrive (2018) and MaxDrive 1.5 mm titanium systems are recommended for midface fractures (e.g., zygomatic or maxillary fractures) and osteotomies (e.g., Le Fort I osteotomy), and the CrossDrive (2018) and MaxDrive 2.0 mm titanium systems for mandibular fractures and osteotomies when a titanium osteosynthesis system is used. When there is an indication for a biodegradable osteosynthesis system, the SonicWeld 2.1 mm or BioSorbFX 2.0 mm are recommended for midface fractures and osteotomies, and the Inion CPS 2.5 mm biodegradable system for mandibular osteotomies and non-load bearing mandibular fractures, especially when high torsional forces are expected (e.g., mandibular symphysis fractures)

Quench Protection Study of a Single-Aperture 11 T Nb3Sn Demonstrator Dipole for LHC Upgrades

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