A method for simply coupling a dielectric resonator (DR) to a standard TE102 rectangular cavity is described. The DR/TE102 resonator is easily realized with minor changes to existing rectangular cavities. In comparison with other resonant structures based on dielectric resonators, coupling of the microwave power to the dielectric is much easier. Its use in electron paramagnetic resonance spectroscopy results in a high filling factor and a high value of the H1 field inside the resonator. It can be particularly useful for pulsed application, where high filling factors are required.

Background The vitamin D role in bone metabolism is well known; however, recent evidence suggests the impact of vitamin D in immune modulation and its implications in immune-mediated diseases, including inflammatory bowel disease (IBD). Method We performed a systematic review with meta-analysis by a specific protocol (PROSPERO: CRD42022311184; March 2022, https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=311184). Randomized clinical trials involving IBD patients treated with vitamin D supplementation, compared with placebo, that evaluated the risk of clinical relapse and disease activity were included. Literature search was performed using Medline, Scopus, and Cochrane CENTRAL through January 2022. Results Out of 1448 articles, 12 (11 full-texts and 1 abstract) were included. Seven randomized clinical trials reported data on the clinical relapse as dichotomous outcome, while 7 studies reported data on disease activity expressed as continuous variables. The pooled risk ratio of clinical relapse was 0.64 (95% confidence interval, 0.46-0.89; I2 = 25%) among 458 IBD patients. However, this seems to be solid only in Crohn’s disease (CD) patients. In fact, only 2 studies, involving 67 patients with ulcerative colitis, were included in the analysis. CD patients in clinical remission had a strong significant risk reduction in clinical relapse (risk ratio, 0.47; 95% confidence interval, 0.27-0.82; I2 = 0%), suggesting that it could be a specific subgroup with maximum clinical benefit of vitamin D supplementation. Conclusions This meta-analysis shows that vitamin D supplementation can reduce the risk of clinical relapse in IBD patients, especially in CD patients in clinical remission. In a subgroup analysis, it was not significant (due to small number of studies and low number of patients), and well-powered studies are needed, in particular for ulcerative colitis patients.

A very compact design for the coil assembly of an X-band imaging apparatus is described. The design is based on D-shaped coils obtained by cutting a circular current distribution by two parallel chords. The coils make the best possible use of the space available within the particular geometry of a cylindrical Bruker TM110 cavity. Its compact design results in a maximum width of 45 mm, which is available in most electromagnets used for electron paramagnetic resonance (EPR) spectroscopy. Using nitroxide free radicals of 60 mT in linewidth and field gradients of 1.5 mT/cm, a resolution of 100 μm was obtained.

A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate.

No abstract