Alkali-metal-mediated zincation (AMMZn) meets N-heterocyclic carbene (NHC) chemistry : Zn–H exchange reactions and structural authentication of a dinuclear Au(I) complex with a NHC anion

Merging two evolving areas in synthesis, namely cooperative bimetallics and N-heterocyclic carbenes (NHCs), this study reports the isolation of the first intermediates of alkali-metal-mediated zincation (AMMZn) of a free NHC and a Zn–NHC complex using sodium zincate [(TMEDA)NaZn(TMP)(tBu)2] (1) as a metallating reagent. The structural authentication of (THF)3Na[:C{[N(2,6-iPr2C6H3)]2CHCZn(tBu2)}] (2) and [Na(THF)6]+[tBu2Zn:C{[N(2,6-iPr2C6H3)]2CHCZn(tBu2)}]− (4), resulting from the reactions of 1 with unsaturated free NHC IPr (IPr = 1,3-bis(2,6-di-isopropylphenylimidazole-2-ylidene) and NHC complex ZntBu2IPr (3) respectively demonstrates that in both cases, this mixed-metal approach can easily facilitate the selective C4 zincation of the unsaturated backbone of the NHC ligand. Furthermore, the generation of anionic NHC fragments enables dual coordination through their normal (C2) and abnormal (C4) positions to the bimetallic system, stabilising the kinetic AMMZn intermediates which normally go undetected and provides new mechanistic insights in to how these mixed-metal reagents operate. In stark contrast to this bimetallic approach when NHC-complex 3 is reacted with a more conventional single-metal base such as tBuLi, the deprotonation of the coordinated carbene is inhibited, favouring instead, co-complexation to give NHC-stabilised [IPr·LiZntBu3] (5). Showing the potential of 2 to act as a transfer agent of its anionic NHC unit to transition metal complexes, this intermediate reacts with two molar equivalents of [ClAu(PPh3)] to afford the novel digold species [ClAu:C{[N(2,6-iPr2C6H3)]2CHCAu(PPh3)}] (6) resulting from an unprecedented double transmetallation reaction which involves the simultaneous exchange of both cationic (Na+) and neutral (ZntBu2) entities on the NHC framework

Real-Time Selective Harmonic Mitigation Technique for Power Converters Based on the Exchange Market Algorithm

Hand-in-hand with the smart-grid paradigm development, power converters used in high-power applications are facing important challenges related to efficiency and power quality. To overcome these issues, the pre-programmed Pulse-Width Modulation (PWM) methods have been extensively applied to reduce the harmonic distortion with very low power switching losses for high-power converters. Among the pre-programmed PWM techniques, Selective Harmonic Elimination (SHE) has been the prevailing solution, but recently, Selective Harmonic Mitigation (SHM) stands as a superior alternative to provide further control of the harmonic spectrum with similar losses. However, the large computational burden required by the SHM method to find a solution confines it as an off-line application, where the switching set valid solutions are pre-computed and stored in a memory. In this paper, for the first time, a real-time implementation of SHM using an off-the-shelf mid-range microcontroller is presented and tested. The Exchange Market Algorithm (EMA), initially focused on optimizing financial transactions, is considered and executed to achieve the SHM targets. The performance of the EMA-based SHM is presented showing experimental results considering a reduced number of switching angles applied to a specific three-level converter, but the method can be extrapolated to any other three-level converter topology.Ministerio de Ciencia e Innovación de España TEC2016-78430-RJunta de Andalucía P18-RT-1340Fondo Nacional de Investigación de Qatar NPRP 9-310-2-13

Innovation in tourism: Re-conceptualising and measuring the absorptive capacity of the hotel sector

Recent reviews of research on innovation in tourism have highlighted a number of weaknesses in the literature. Among these is the limited theorising and empirical investigation of innovative practices by tourism organisations. This paper responds to these concerns by examining one important dimension of innovation within commercial tourism organisations, namely their ability to acquire, assimilate and utilise external knowledge (absorptive capacity) for competitive advantage. The topic is pertinent because there is evidence to suggest that tourism organisations are particularly dependent on external sources of knowledge when compared with businesses in other sectors. Following a discussion of the conceptual antecedents of absorptive capacity and its dimensions, a validated instrument for its measurement is developed and used to measure the absorptive capacity of the British hotel sector. The results suggest that current conceptions of absorptive capacity have limitations when applied to tourism enterprises. Absorptive capacity is re-conceptualised to overcome these deficiencies. The research and policy implications of the findings are discussed. © 2014 Elsevier Ltd

Persistent HIV-controllers are more prone to spontaneously clear HCV: a retrospective cohort study.

HIV-controllers have the ability to spontaneously maintain viraemia at low or undetectable levels in the absence of antiretroviral treatment. Furthermore, HIV-controllers seem to have a superior capacity to spontaneously clear hepatitis C virus (HCV) compared to non HIV-controllers. Some of these subjects eventually lose HIV-controller status (transient controllers), whereas some HIV-controllers show a persistent natural HIV control (persistent controllers). We aimed to analyse whether persistent controllers have superior capacity to spontaneously clear HCV compared to transient controllers. We recruited HIV-controllers from January 1981 up to October 2016 with available antibodies to HCV (anti-HCV) data (n = 744). Factors associated with HIV spontaneous control in relation to HCV status were analysed in persistent and transient HIV-controllers with anti-HCV positive (n = 202 and n = 138 respectively) in comparison with 1700 HCV positive non HIV-controllers recruited from January 1981 up to March 2018, bivariate and multivariate analyses, following a logistic regression model, were applied. In addition, the factors related to the loss and time to lose HIV-controller status were explored (n = 744) using Log rank test and Kaplan-Meier curves, in this case the multivariate analysis consisted in a Cox regression model. A higher frequency of HCV spontaneous clearance was found in persistent HIV-controllers (25.5%) compared to non-controllers (10.2%). After adjusting for potential confounders, as sex, age, HIV transmission risk, CD4+ T-cell nadir and time of follow-up, HCV clearance was independently associated with persistent HIV spontaneous control (p = 0.002; OR (95% CI) = 2.573 (1.428 to 4.633)), but not with transient spontaneous control (p = 0.119; 1.589 (0.888 to 2.845)). Furthermore, persistent HIV-controllers were more likely to spontaneously clear the HCV in comparison with transient controllers (p = 0.027; 0.377 (0.159 to 0.893). Finally, not to lose or lengthen the time of losing this control was independently associated with HCV spontaneous clearance (p = 0.010; 0.503 (0.297 to 0.850). This study shows an association between spontaneous persistent HIV-control and HCV spontaneous clearance. The study findings support the idea of preserved immune mechanisms in persistent HIV control implicated in HCV spontaneous clearance. These results highlight persistent HIV-controllers but not transient controllers as a good model of functional HIV cure.This work was supported by the Instituto de Salud Carlos III (research contracts CPII014/00025 to E.R.‐M., and FI14/00431 to L.T.‐D. and research projects PI12/02283, PI16/00684, PI19/01127 to E.R.‐M.) and Red Temática de Investigación Cooperativa en SIDA (Projects RD12/0017/0029, RD12/0017/0031, and RD16/0025/0020 and RD16/0025/0013), which is included in the Acción Estratégica en Salud, Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008 to 2011 and 2013 to 2016, Instituto de Salud Carlos III, Fondos FEDER. E.R.‐M. was supported by Consejería de Salud y Bienestar Social of Junta de Andalucía through the Nicolás Monardes program (C‐0032/17), N Rallón is a Miguel Servet investigator from the Spanish Carlos III Institute of Health (ISCIII), grant CP14/00198, Madrid, Spain and B.D.M. received a grant from The Spanish Ministry of Education (FPU13/02451). Work in CL‐G’s laboratory was supported by grants SAF (2010 to 17226) and (2016‐77894‐R) from MINECO (Spain) and FIS (PI 13/02269, ISCIII) and in part by the RIS‐RETIC grants RD06/006/0036 and RD12/0017/0028 funded by the ISC III‐FEDER. MP has a contract of RIS‐RETIC RD12/0017/0036.S

Factors associated with the development of septic shock in patients with candidemia: A post hoc analysis from two prospective cohorts

Background: Almost one third of the patients with candidemia develop septic shock. The understanding why some patients do and others do not develop septic shock is very limited. The objective of this study was to identify variables associated with septic shock development in a large population of patients with candidemia. Methods: A post hoc analysis was performed on two prospective, multicenter cohort of patients with candidemia from 12 hospitals in Spain and Italy. All episodes occurring from September 2016 to February 2018 were analyzed to assess variables associated with septic shock development defined according to The Third International Consensus Definition for Sepsis and Septic Shock (Sepsis-3). Results: Of 317 candidemic patients, 99 (31.2%) presented septic shock attributable to candidemia. Multivariate logistic regression analysis identifies the following factors associated with septic shock development: age > 50 years (OR 2.57, 95% CI 1.03-6.41, p = 0.04), abdominal source of the infection (OR 2.18, 95% CI 1.04-4.55, p = 0.04), and admission to a general ward at the time of candidemia onset (OR 0.21, 95% CI, 0.12-0.44, p = 0.001). Septic shock development was independently associated with a greater risk of 30-day mortality (OR 2.14, 95% CI 1.08-4.24, p = 0.02). Conclusions: Age and abdominal source of the infection are the most important factors significantly associated with the development of septic shock in patients with candidemia. Our findings suggest that host factors and source of the infection may be more important for development of septic shock than intrinsic virulence factors of organisms

Remdesivir in Very Old Patients (≥80 Years) Hospitalized with COVID-19: Real World Data from the SEMI-COVID-19 Registry

Background: Large cohort studies of patients with COVID-19 treated with remdesivir have reported improved clinical outcomes, but data on older patients are scarce. Objective: This work aims to assess the potential benefit of remdesivir in unvaccinated very old patients hospitalized with COVID-19; (2) Methods: This is a retrospective analysis of patients >= 80 years hospitalized in Spain between 15 July and 31 December 2020 (SEMI-COVID-19 Registry). Differences in 30-day all-cause mortality were adjusted using a multivariable regression analysis. (3) Results: Of the 4331 patients admitted, 1312 (30.3%) were >= 80 years. Very old patients treated with remdesivir (n: 140, 10.7%) had a lower mortality rate than those not treated with remdesivir (OR (95% CI): 0.45 (0.29-0.69)). After multivariable adjustment by age, sex, and variables associated with lower mortality (place of COVID-19 acquisition; degree of dependence; comorbidities; dementia; duration of symptoms; admission qSOFA; chest X-ray; D-dimer; and treatment with corticosteroids, tocilizumab, beta-lactams, macrolides, and high-flow nasal canula oxygen), the use of remdesivir remained associated with a lower 30-day all-cause mortality rate (adjusted OR (95% CI): 0.40 (0.22-0.61) (p < 0.001)). (4) Conclusions: Remdesivir may reduce mortality in very old patients hospitalized with COVID-19

A hemilabile and cooperative N-donor functionalized 1,2,3-triazol- 5-ylidene ligand for selective and base-free rhodium(I) catalyzed alkyne hydrothiolation reactions

A series of novel cationic and neutral Rh-complexes with an N-donor functionalized 1,2,3-triazol-5-ylidene (TRZ) ligand (where pendant N-donor is NHBoc, NH2 or NMe2 respectively) is described. Their catalytic activity was evaluated towards the hydrothiolation of alkynes. Among the catalysts, a neutral dicarbonyl complex featuring the tethered-NBoc amido-TRZ ligand proved very selective for alkyne hydrothiolation with an aryl thiol. Remarkably, the reaction could be carried out in the absence of pyridine or base additive. In addition, during the reaction course, no evidence for oxidative addition of the thiol S-H was observed, strongly suggesting a reaction pathway whereby a bifunctional ligand is involved. Experimental and theoretical mechanistic investigations suggest a ligand-assisted deprotonation of substrate thiol, hemilabile dissociation of amine from metal and thiolate coordination, which is indicative of a different reaction mechanism to those previously reported for related alkyne hydrothiolation reaction.G. G.-B. thanks the MINECO for a postdoctoral grant (FPDI- 2013-16525) and Generalitat Valenciana (GV/2015/097) for financial support. E.P and I.F. gratefully acknowledge financial support from the Spanish MINECO-FEDER (CTQ2014-51999-P to E.P. and CTQ2013-44303-P and CTQ2014-51912-REDC to I.F.), UJI (P11B2014-02 to E.P.). D.I.B and I.S. gratefully acknowledge the National Research Foundation, South Africa (NRF 87890, 103698 and 92521), and Sasol Technology R&D Pty. Ltd., South Africa for financial support.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-37652018-01-31hb2017Chemistr

Association between convalescent plasma treatment and mortality in COVID-19: a collaborative systematic review and meta-analysis of randomized clinical trials.

Funder: laura and john arnold foundationBACKGROUND: Convalescent plasma has been widely used to treat COVID-19 and is under investigation in numerous randomized clinical trials, but results are publicly available only for a small number of trials. The objective of this study was to assess the benefits of convalescent plasma treatment compared to placebo or no treatment and all-cause mortality in patients with COVID-19, using data from all available randomized clinical trials, including unpublished and ongoing trials (Open Science Framework, https://doi.org/10.17605/OSF.IO/GEHFX ). METHODS: In this collaborative systematic review and meta-analysis, clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed were searched until April 8, 2021. Investigators of trials registered by March 1, 2021, without published results were contacted via email. Eligible were ongoing, discontinued and completed randomized clinical trials that compared convalescent plasma with placebo or no treatment in COVID-19 patients, regardless of setting or treatment schedule. Aggregated mortality data were extracted from publications or provided by investigators of unpublished trials and combined using the Hartung-Knapp-Sidik-Jonkman random effects model. We investigated the contribution of unpublished trials to the overall evidence. RESULTS: A total of 16,477 patients were included in 33 trials (20 unpublished with 3190 patients, 13 published with 13,287 patients). 32 trials enrolled only hospitalized patients (including 3 with only intensive care unit patients). Risk of bias was low for 29/33 trials. Of 8495 patients who received convalescent plasma, 1997 died (23%), and of 7982 control patients, 1952 died (24%). The combined risk ratio for all-cause mortality was 0.97 (95% confidence interval: 0.92; 1.02) with between-study heterogeneity not beyond chance (I2 = 0%). The RECOVERY trial had 69.8% and the unpublished evidence 25.3% of the weight in the meta-analysis. CONCLUSIONS: Convalescent plasma treatment of patients with COVID-19 did not reduce all-cause mortality. These results provide strong evidence that convalescent plasma treatment for patients with COVID-19 should not be used outside of randomized trials. Evidence synthesis from collaborations among trial investigators can inform both evidence generation and evidence application in patient care