Structure and photophysics of rubrene-tetracene blends

The application potential of singlet fission (SF), describing the spontaneous conversion of an excited singlet into two triplets, underlines the necessity to independently control SF rates, energetics and the optical band gap. Heterofission, whereby the singlet splits into triplets on chemically distinct chromophores, is a promising approach to control the above-mentioned parameters, but its details are not yet fully understood. Here, we investigate the photophysics of blends of two prototypical SF chromophores, tetracene (TET) and rubrene (RUB) using time-resolved photoluminescence spectroscopy and time-correlated single photon counting (TCSPC) to explore the potential for heterofission in combinations of endothermic SF chromophores.

The Biocatalytic Production of 3-Hydroxypropionaldehyde and Evaluation of Its Stability

3-Hydroxypropionaldehyde (3-HPA, reuterin) is a broad-spectrum natural antimicrobial agent used in the food industry and other fields. The low yield from the industrial production of 3-HPA using Lactobacillus reuteri and the spontaneous conversion of 3-HPA to acrolein have limited its more widespread use. We isolated L. reuteri BR201 as a biocatalyst for 3-HPA production and confirmed the effect of each factor in the two-step procedure for 3-HPA bioconversion. After initial cultivation for 8 h (late exponential phase), this isolate produced 378 mM of 3-HPA in 1 h at a concentration of OD600 nm 100, 30 °C, and an initial glycerol concentration of 500 mM. This is the highest reported biocatalytic yield of 3-HPA from a glycerol aqueous solution without additives. We confirmed that 4 mM of 3-HPA had antimicrobial activity against five pathogens. The degradation of 3-HPA to acrolein was greater at high temperatures, and there was little degradation when 3-HPA was maintained at 4 °C for 4 weeks. Our results may be useful for future applications of 3-HPA.

Muonium-Antimuonium Conversion

The MACS experiment performed at PSI in the 1990s provided an yet unchallenged upper bound on the probability for a spontaneous conversion of the muonium atom, { M=}({\mu^+e^-})M=(μ+e−), into its antiatom, antimuonium {\overline{{M}} = }({\mu^-e^+})M¯=(μ−e+). It comprises the culmination of a series of measurements at various accelerator laboratories worldwide. The experimental limits on the process have provided input and steering for the further development of a variety of theoretical models beyond the standard theory, in particular for models which address lepton number violating processes and matter-antimatter oscillations. Several models beyond the standard theory could be strongly disfavored. There is interest in a new measurement and improved sensitivity could be reached by exploiting the time evolution of the conversion process, e.g., at intense pulsed muonium sources.

Conversion from type 2 to type 1 macular hole closure after surgery in high myopia

We describe a case of spontaneous conversion from type 2 macular hole (MH) closure to type 1 closure following MH surgery in high myopia. A 42-year-old male patient with myopia was diagnosed with full-thickness MH and localised neurosensory detachment. His best-corrected vision in the right eye was 20/120, N18. He underwent pars plana vitrectomy with internal limiting membrane peeling and silicone oil tamponade. Nine days after surgery, optical coherence tomography (OCT) showed type 2 MH closure and presence of epiretinal tissue. At 6 weeks of follow-up, there was spontaneous conversion from type 2 to type 1 closure of MH with a thin epimacular tissue bridging across the fovea and vision improving to 20/80. At 3 months after surgery, silicon oil removal was done. OCT showed a closed type 1 MH and visual acuity of 20/80 at the final visit. Early spontaneous conversion in closure can occur over time, leading to better anatomical and visual outcomes.

Clinical determinants of early spontaneous conversion to sinus rhythm in patients with atrial fibrillation

Background The current standard of care for acute atrial fibrillation (AF) focuses primarily on immediate restoration of sinus rhythm by cardioversion, although AF often terminates spontaneously. Objective To identify determinants of early spontaneous conversion (SCV) in patients presenting at the emergency department (ED) because of AF. Methods An observational study was performed of patients who visited the ED with documented AF between July 2014 and December 2016. The clinical characteristics and demographics of patients with and without SCV were compared. Results We enrolled 943 patients (age 69 ± 12 years, 47% female). SCV occurred within 3 h of presentation in 158 patients (16.8%). Logistic regression analysis showed that duration of AF <24 h [odds ratio (OR) 7.7, 95% confidence interval (CI) 3.5–17.2, p < 0.001], left atrial volume index <42 ml/m2 (OR 1.8, 95% CI 1.2–2.8, p = 0.010), symptoms of near-collapse at presentation (OR 2.4, 95% CI 1.2–5.1, p = 0.018), a lower body mass index (BMI) (OR 0.9, 95% CI 0.91–0.99, p = 0.028), a longer QTc time during AF (OR 1.01, 95% CI 1.0–1.02, p = 0.002) and first-detected AF (OR 2.5, 95% CI 1.6–3.9, p < 0.001) were independent determinants of early SCV. Conclusion Early spontaneous conversion of acute AF occurs in almost one-sixth of admitted patients during a short initial observation in the ED. Spontaneous conversion is most likely to occur in patients with first-onset, short-duration AF episodes, lower BMI, and normal left atrial size.

Spontaneous conversion of prenyl halides to acid: Application for metal-free preparation of deuterated compounds under mild conditions

Here we reveal a simple generation of deuterium halide (DX) from common and inexpensive reagents readily available in a synthetic chemistry laboratory, i.e. prenyl-, allyl-, and propagyl halides, under mild...

Frequency and Determinants of Spontaneous Conversion to Sinus Rhythm in Patients Presenting to the Emergency Department with Recent-onset Atrial Fibrillation: A Systematic Review

The exact frequency and clinical determinants of spontaneous conversion (SCV) in patients with symptomatic recent-onset AF are unclear. The aim of this systematic review is to provide an overview of the frequency and determinants of SCV of AF in patients presenting at the emergency department. A comprehensive literature search for studies about SCV in patients presenting to the emergency department with AF resulted in 25 articles – 12 randomised controlled trials and 13 observational studies. SCV rates range between 9–83% and determinants of SCV also varied between studies. The most important determinants of SCV included short duration of AF (<24 or <48 hours), low number of episodes, normal atrial dimensions and absence of previous heart disease. The large variation in SCV rate and determinants of SCV was related to differences in duration of the observation period, inclusion and exclusion criteria and in variables used in the prediction models.