Aluminum porphyrins with quaternary ammonium halides as catalysts for copolymerization of cyclohexene oxide and CO2: metal–ligand cooperative catalysis

Bifunctional AlIII porphyrins with quaternary ammonium halides, 2-Cl and 2-Br, worked as excellent catalysts for the copolymerization of cyclohexene oxide (CHO) and CO2 at 120 °C. Turnover frequency (TOF) and turnover number (TON) reached 10 000 h−1 and 55 000, respectively, and poly(cyclohexene carbonate) (PCHC) with molecular weight of up to 281 000 was obtained with a catalyst loading of 0.001 mol%. In contrast, bifunctional MgII and ZnII counterparts, 3-Cl and 4-Cl, as well as a binary catalyst system, 1-Cl with bis(triphenylphosphine)iminium chloride (PPNCl), showed poor catalytic performances. Kinetic studies revealed that the reaction rate was first-order in [CHO] and [2-Br] and zero-order in [CO2], and the activation parameters were determined: ΔH‡ = 12.4 kcal mol−1, ΔS‡ = −26.1 cal mol−1 K−1, and ΔG‡ = 21.6 kcal mol−1 at 80 °C. Comparative DFT calculations on two model catalysts, AlIII complex 2′ and MgII complex 3′, allowed us to extract key factors in the catalytic behavior of the bifunctional AlIII catalyst. The high polymerization activity and carbonate-linkage selectivity originate from the cooperative actions of the metal center and the quaternary ammonium cation, both of which facilitate the epoxide-ring opening by the carbonate anion to form the carbonate linkage in the key transition state such as TS3b (ΔH‡ = 13.3 kcal mol−1, ΔS‡ = −3.1 cal mol−1 K−1, and ΔG‡ = 14.4 kcal mol−1 at 80 °C)

Relation between psychosocial variables and the glycemic control of patients with type 2 diabetes: A cross-sectional and prospective study

<p>Abstract</p> <p>Background</p> <p>This cross-sectional and prospective study used a variety of psychological inventories to evaluate the relationship between psychosocial factors and the glycemic control of patients with type 2 diabetes.</p> <p>Methods</p> <p>Participants were 304 patients with type 2 diabetes who were treated as outpatients at diabetes clinics. All participants were assessed for HbA_1cand completed the following self-report psychological inventories: 1) Diabetes Treatment Satisfaction Questionnaire (DTSQ), 2) Problem Areas in Diabetes Survey (PAID), 3) Well-being Questionnaire 12 (W-BQ12), 4) Self-Esteem Scale (SES), 5) Social Support Scale, and 6) Self-Efficacy Scale. HbA_1cwas again measured one year later. The relationships between the psychosocial variables obtained by analysis of the psychological inventories and baseline or one-year follow-up HbA_1cwere determined.</p> <p>Results</p> <p>Baseline HbA_1cwas significantly correlated with age, diet treatment regimen, number of microvascular complication of diabetes, and the total scores of DTSQ, W-BQ12, PAID, SES and the Self-Efficacy Scale. Hierarchical stepwise multiple regression revealed that significant predictors of baseline HbA_1cwere total DTSQ and PAID scores, along with age, diet treatment regimen, and number of microvascular complication of diabetes after adjustment for demographic, clinical and other psychosocial variables. Two hundred and ninety patients (95.4% of 304) were followed and assessed one year after baseline. Hierarchical stepwise multiple regression analysis showed the significant predictors of follow-up HbA_1cto be total DTSQ and PAID scores, along with age and diet treatment regimen. However, the correlation between baseline and follow-up HbA_1cwas so high that the only other variable to retain significance was diet treatment regimen once baseline HbA_1cwas included in the regression of follow-up HbA_1c.</p> <p>Conclusion</p> <p>The DTSQ and the PAID predicted both current and future HbA_1cto a similar and significant degree in patients with type 2 diabetes.</p

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects