A Formal Rearrangement of Allylic Silanols Dhokale, Ranjeet A.; Seidl, Frederick J.; Sathyamoorthi, Shyam
Molecules (Basel, Switzerland),
06/2021, Letnik:
26, Številka:
13
Journal Article
Recenzirano
Odprti dostop
We show that 1M aqueous HCl/THF or NaBH4/DMF allows for demercurative ring-opening of cyclic organomercurial synthons into secondary silanol products bearing terminal alkenes. We had previously ...demonstrated that primary allylic silanols are readily transformed into cyclic organomercurials using Hg(OTf)2/NaHCO3 in THF. Overall, this amounts to a facile two-step protocol for the rearrangement of primary allylic silanol substrates. Computational investigations suggest that this rearrangement is under thermodynamic control and that the di-tert-butylsilanol protecting group is essential for product selectivity.
Abstract
One of the remaining challenges in magnetic thermonuclear fusion is survival of the heat shield protecting the tokamak reactor vessel against excessive plasma heat fluxes. Unmitigated high ...confinement edge localized mode (ELM) is a regular heat pulse damaging the heat shield. We suggest a novel concept of magnetic sweeping of the plasma contact strike point fast and far enough in order to spread this heat pulse. We demonstrate feasibility of a dedicated copper coil in a resonant circuit, including the induced currents and power electronics. We predict the DEMO ELM properties, simulate heat conduction, 3D particles motion and magnetic fields of the plasma and coil in COMSOL Multiphysics and Matlab. The dominant system parameter is voltage, feasible 18 kV yields 1 kHz sweeping frequency, suppressing the ELM-induced surface temperature rise by a factor of 3. Multiplied by other known mitigation concepts, ELMs might be mitigated enough to ensure safe operation of DEMO.
Background:
Arthroscopic stabilization has been established as a superior treatment option for primary glenohumeral instability when compared with immobilization in internal rotation. However, ...immobilization in external rotation (ER) has recently gained interest as a viable nonoperative treatment option for patients with shoulder instability.
Purpose:
To compare the rates of recurrent instability and subsequent surgery in patients undergoing treatment for primary anterior shoulder dislocation with arthroscopic stabilization versus immobilization in ER.
Study Design:
Systematic review; Level of evidence, 2.
Methods:
A systematic review was performed by searching PubMed, the Cochrane Library, and Embase to identify studies that’evaluated patients being treated for primary anterior glenohumeral dislocation with either arthroscopic stabilization or immobilization in ER. The search phrase used various combinations of the keywords/phrases “primary closed reduction,”“anterior shoulder dislocation,”“traumatic,”“primary,”“treatment,”“management,”“immobilization,”“external rotation,”“surgical,”“operative,”“nonoperative,” and “conservative.” Inclusion criteria included patients undergoing treatment for primary anterior glenohumeral joint dislocation with either immobilization in ER or arthroscopic stabilization. Rates of recurrent instability, subsequent stabilization surgery, return to sports, positive postintervention apprehension tests, and patient-reported outcomes were evaluated.
Results:
The 30 studies that met inclusion criteria included 760 patients undergoing arthroscopic stabilization (mean age, 23.1 years; mean follow-up time, 55.1 months) and 409 patients undergoing immobilization in ER (mean age, 29.8 years; mean follow-up time, 28.8 months). Overall, 8.8% of operative patients experienced recurrent instability at latest follow-up compared with 21.3% of patients who had undergone ER immobilization (P < .0001). Similarly, 5.7% of operative patients had undergone a subsequent stabilization procedure at latest follow-up compared with 11.3% of patients who had undergone ER immobilization (P = .0015). A higher rate of return to sports was found in the operative group (P < .05), but no other differences were found between groups.
Conclusion:
Patients undergoing arthroscopic treatment for primary anterior glenohumeral dislocation with arthroscopic stabilization can be expected to experience significantly lower rates of recurrent instability and subsequent stabilization procedures compared with patients undergoing ER immobilization.
Reverse shoulder arthroplasty (RSA) was designed for the treatment of elderly patients with cuff tear arthropathy. Because of its success, the indications for RSA have expanded beyond cuff tear ...arthropathy to include acute fractures, fracture sequelae, massive rotator cuff tears, inflammatory arthritis, and revision shoulder arthroplasty. Consequently, the number of RSAs performed has increased steadily. Glenoid bone loss is not uncommon in patients undergoing primary or revision RSA. Failure to appreciate and address glenoid bone loss during RSA can lead to improper baseplate positioning and early failure or complications such as dislocation or scapular notching. The authors present a review of the current literature as well as recommended strategies for characterization of glenoid bone loss and preferred surgical techniques for addressing bone loss during RSA.
We report a method for growing rectangular InAs nanofins with deterministic length, width, and height by dielectric-templated selective-area epitaxy. These freestanding nanofins can be transferred to ...lay flat on a separate substrate for device fabrication. A key goal was to regain a spatial dimension for device design compared to nanowires, while retaining the benefits of bottom-up epitaxial growth. The transferred nanofins were made into devices featuring multiple contacts for Hall effect and four-terminal resistance studies, as well as a global back-gate and nanoscale local top-gates for density control. Hall studies give a 3D electron density 2.5–5 × 1017 cm–3, corresponding to an approximate surface accumulation layer density 3–6 × 1012 cm–2 that agrees well with previous studies of InAs nanowires. We obtain Hall mobilities as high as 1200 cm2/(V s), field-effect mobilities as high as 4400 cm2/(V s), and clear quantum interference structure at temperatures as high as 20 K. Our devices show excellent prospects for fabrication into more complicated devices featuring multiple ohmic contacts, local gates, and possibly other functional elements, for example, patterned superconductor contacts, that may make them attractive options for future quantum information applications.
This paper summarizes the status of the COMPASS tokamak, its comprehensive diagnostic equipment and plasma scenarios as a baseline for the future studies. The former COMPASS-D tokamak was in ...operation at UKAEA Culham, UK in 1992-2002. Later, the device was transferred to the Institute of Plasma Physics of the Academy of Sciences of the Czech Republic (IPP AS CR), where it was installed during 2006-2011. Since 2012 the device has been in a full operation with Type-I and Type-III ELMy H-modes as a base scenario. This enables together with the ITER-like plasma shape and flexible NBI heating system (two injectors enabling co- or balanced injection) to perform ITER relevant studies in different parameter range to the other tokamaks (ASDEX-Upgrade, DIII-D, JET) and to contribute to the ITER scallings. In addition to the description of the device, current status and the main diagnostic equipment, the paper focuses on the characterization of the Ohmic as well as NBI-assisted H-modes. Moreover, Edge Localized Modes (ELMs) are categorized based on their frequency dependence on power density flowing across separatrix. The filamentary structure of ELMs is studied and the parallel heat flux in individual filaments is measured by probes on the outer mid-plane and in the divertor. The measurements are supported by observation of ELM and inter-ELM filaments by an ultra-fast camera.
The DNA-end-joining reactions used for repair of double-strand breaks in DNA and for V (D)J recombination, the process by which immunoglobulin and T-cell antigen-receptor genes are assembled from ...multiple gene segments, use common factors. These factors include components of DNA-dependent protein kinase (DNA-PK), namely DNA-PKcs and the Ku heterodimer, Ku70-Ku80, and XRCC4 (ref. 1). The precise function of XRCC4 is unknown, but it interacts with DNA ligase IV. Ligase IV is one of the three known mammalian DNA ligases; however, the in vivo functions of these ligases have not been determined unequivocally. Here we show that inactivation of the ligase IV gene in mice leads to late embryonic lethality. Lymphopoiesis in these mice is blocked and V (D)J joining does not occur. Ligase IV-deficient embryonic fibroblasts also show marked sensitivity to ionizing radiation, growth defects and premature senescence. All of these phenotypic characteristics, except embryonic lethality, resemble those associated with Ku70 and Ku80 deficiencies, indicating that they may result from an impaired end-joining process that involves both Ku subunits and ligase IV. However, Ku-deficient mice are viable, so ligase IV must also be required for processes and/or in cell types in which Ku is dispensable.
Peptoids (N-substituted glycine oligomers) are widely used peptidomimetics, and an enhanced understanding of their structures is needed to expand their utility, particularly in aqueous applications. ...We report the synthesis and structural study of four water-soluble peptoids that include strongly helix-promoting (S)-N-1-(naphthylethyl)glycine residues. Peptoid structure changes with both peptoid length and solvent composition. Multiple data support the self-association of the longest peptoid studied here, 1, via hydrophobic interactions in aqueous solutions.
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