320 research outputs found

    Aerobic Oxidations Mediated by Allylnickel(N-Heterocyclic Carbene)Chloride Complexes: Investigating the Role of a Pendent Amine Group

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    Molecular oxygen (O2) represents the most ideal green oxidant for the large-scale oxidation of organic compounds, due to its inexpensive and environmentally benign characteristics. However, a number of challenges remain for its use in the fine chemical and pharmaceutical industry, including the development of highly selective catalytic transformations. NiCl(allyl)(NHC) complexes have been shown to react with O2 to promote the oxidation of the allylic ligand, however non-catalytically. This report details the synthesis and characterization of novel NiCl(cinnamyl/allyl)(NHC) complexes, containing a pendent 2° amine arm on the NHC ligand to act as a hydrogen-bond donor group. The complexes prove to exhibit dynamic behavior, with the pendent amine showing the ability for hydrogen-bonding and/or hemi-labile ligand coordination to the metal. Dioxygen reactivity studies indicate that the complexes are active for aerobic oxidation, and that the product distribution is different than that of previously reported systems. However, the observed reactivity currently is non-catalytic

    Catalytic cyclization and competitive deactivation with Ru(P\u3csup\u3eR\u3c/sup\u3e2N\u3csup\u3eR′\u3c/sup\u3e2) complexes

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    The first successful use of the PR2NR′2 (1,5-R′-3,7-R-1,5-diaza-3,7-diphosphacyclooctane) ligand family toward an organic synthesis is described. The precatalysts [Ru(Cp)(PR2NBn2)(MeCN)]PF6 are active toward cyclization of 2-ethynylbenzyl alcohol at low catalyst loading and mild temperatures. Catalyst performance however is limited by both low conscription and by competitive deactivation

    Catalytic Acceptorless Dehydrogenation of Amines with Ru(P\u3csup\u3eR\u3c/sup\u3e2N\u3csup\u3eR′\u3c/sup\u3e2) and Ru(dppp) Complexes

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    [Ru(Cp)(PPh2NBn2)(MeCN)]PF6 (1; PPh2NBn2 = 1,5-benzyl-3,7-phenyl-1,5-diaza-3,7-diphosphacyclooctane) and [Ru(Cp)(dppp)(MeCN)]PF6 (2; dppp = 1,3-bis(diphenylphosphino)propane) are both active toward the acceptorless dehydrogenation of benzylamine (BnNH2) and N-heterocycles. The two catalysts have similar activities but different selectivities for dehydrogenation products. Independent synthesis of a [Ru(Cp)(PPh2NBn2)(NH2Bn)]PF6 adduct (3) reveals the presence of a hydrogen bond between the bound amine and the pendent base of the PPh2NBn2 ligand. Preliminary mechanistic studies reveal that the benzylamine adduct is not an on-cycle catalyst intermediate

    Developing Integrated Clinical Pathways for the Management of Clinically Severe Adult Obesity: a Critique of NHS England Policy

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    Purpose of the Review: Pathways for obesity prevention and treatment are well documented, yet the prevalence of obesity is rising, and access to treatment (including bariatric surgery) is limited. This review seeks to assess the current integrated clinical pathway for obesity management in England and determine the major challenges. Recent Findings: Evidence for tier 2 (community-based lifestyle intervention) and tier 3 (specialist weight management services) is limited, and how it facilitates care and improve outcomes in tier 4 remains uncertain. Treatment access, rigidity in pathways, uncertain treatment outcomes and weight stigma seems to be major barriers to improved care. Summary: More emphasis must be placed on access to effective treatments, treatment flexibility, addressing stigma and ensuring treatment efficacy including long-term health outcomes. Prevention and treatment should both receive significant focus though should be considered to be largely separate pathways. A simplified system for weight management is needed to allow flexibility and the delivery of personalized care including post-bariatric surgery care for those who need it

    Performance Measures Using Electronic Health Records: Five Case Studies

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    Presents the experiences of five provider organizations in developing, testing, and implementing four types of electronic quality-of-care indicators based on EHR data. Discusses challenges, and compares results with those from traditional indicators

    Contact Discontinuities in Models of Contact Binaries Undergoing Thermal Relaxation Oscillations

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    In this paper we pursue the suggestion by Shu, Lubow & Anderson (1979) and Wang (1995) that contact discontinuity (DSC) may exist in the secondary in the expansion TRO (thermal relaxation oscillation) state. It is demonstrated that there is a mass exchange instability in some range of mass ratio for the two components. We show that the assumption of {\it constant} volume of the secondary should be relaxed in DSC model. For {\it all} mass ratio the secondary alway satisfies the condition that no mass flow returns to the primary through the inner Lagrangian point. The secondary will expand in order to equilibrate the interaction between the common convective envelope and the secondary. The contact discontinuity in contact binary undergoing thermal relaxation does not violate the second law of thermodynamics. The maintaining condition of contact discontinuity is derived in the time-dependent model. It is desired to improve the TRO model with the advanced contact discontinuity layer in future detailed calculations.Comment: 5 pages in emulateapj, 1 figur

    Does a Healthy Weight Body Mass Index at Onset of Idiopathic Intracranial Hypertension Change the Outcomes? A United Kingdom Prospective Cohort Study

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    Idiopathic intracranial hypertension (IIH) predominantly affects reproductive-aged females with obesity. However, the prevalence and impact of a healthy weight body mass index (BMI) at disease presentation is not known. This study aimed to evaluate the visual and headache outcomes stratified by the presenting BMI. This was a longitudinal prospective cohort study (IIH Life) based on a tertiary neuro-ophthalmology IIH service, University Hospitals Birmingham NHS Trust, United Kingdom, recruiting consecutive patients living with IIH between 2012 and 2021. Those with a presenting BMI were included. The outcome measures included visual outcomes of LogMAR visual acuity, Humphrey visual field perimetric mean deviation (PMD), optical coherence tomography (OCT) measurements, and headache outcomes of frequency, severity, and Headache Impact Test-6 score. Three hundred seventy-five people with IIH and a documented baseline BMI. About 3.7% of the entire cohort had a healthy weight BMI at IIH presentation and 15.5% BMI < 30 kg/m2. The baseline PMD was worse in patients without obesity; however, OCT papilloedema measures were similar. The presence of obesity was associated with a small but significant greater worsening in visual acuity but slower macular ganglion cell layer loss. There was no impact on PMD or papilloedema prognosis related to baseline obesity. The headache outcomes showed heterogeneity, with worse baseline headache frequency in patients with obesity. No BMI group was associated with worse headache outcomes. Patients with a healthy weight BMI or those without obesity at baseline make up a small proportion of IIH patients. BMI at presentation does not appear to influence long-term visual or headache outcomes

    Phosphine-imine and-enamido ligands for acceptorless dehydrogenation catalysis

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    A highly tunable phosphine-imine ligand family is introduced. Following metallation with ruthenium, deprotonation of the ligand affords a phosphine-enamido species. Complexes with the ligand in both the imine and enamido forms are active toward acceptorless dehydrogenation reactions
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