Electrostatic Screening of Charged Defects in Monolayer MoS2.

Defects in monolayer transition-metal dichalcogenides (TMDCs) may lead to unintentional doping, charge-carrier trapping, and nonradiative recombination. These effects impair electronic and optoelectronic technologies. Here we show that charged defects in MoS2 monolayers can be effectively screened when they are in contact with an ionic liquid (IL), leading to an increase in photoluminescence (PL) yield by up to two orders of magnitude. The extent of this PL enhancement by the IL correlates with the brightness of each pretreated sample. We propose the existence of two classes of nonradiative recombination centers in monolayer MoS2: (i) charged defects that relate to unintentional doping and may be electrostatically screened by ILs and (ii) neutral defects that remain unaffected by the presence of ILs.

[Evaluation of 2 dosages of fentanyl in caudal anesthesia. A prospective randomized double-blind study]. / Evaluation de deux posologies de fentanyl en anesthésie caudale. Etude prospective randomisée en double aveugle.

A caudal block is currently performed in children. A randomized and double blind study including two dosages of fentanyl: 0.5 microgram.kg-1 (group I) and 1 micrograms.kg-1 (group II) in association with bupivacaine 0.25% at a dosage of 1 mL.kg-1 was carried out. Two groups of 25 children undergoing urogenital or orthopaedic surgery participated in this study. Analgesia and side effects were evaluated 24 hours postoperatively. Quality and duration of analgesia were similar in the two groups. Furthermore, recovery of anaesthesia was rapid and calm. The frequency of nausea and vomiting was respectively 24% and 20% in groups I and II and did not require any specific therapy. Therefore it appears that caudal block with bupivacaine 0.25% and fentanyl 0.5 microgram.kg-1 is a very satisfactory technique in children when indicated.

[Inefficacy of diltiazem in restenosis prevention after coronary angioplasty]. / Ineficácia do diltiazem na prevenção da reestenose após angioplastia coronária.

PURPOSE: To evaluate the efficacy of diltiazem in preventing restenosis after balloon angioplasty (PTCA). METHODS: Eighty-nine patients who were undergone to successful PTCA, were divided them in 2 groups (G): A) 44 patients (50%) who received diltiazem (180 mg tid) immediately after PTCA and were kept on it for 6 months); B) 45 patients (50%) who received placebo. Fifty two lesions were dilated in GA and 54 in GB. Patients were excluded from analysis for several reasons, including: necessity of diltiazem or others calcium channel blockers use; heart failure, bradicardia, AV block of any degree, PTCA to chronic total occlusion, ostial lesions and AMI less than 30 days prior to PTCA. Patients were randomized to either the active drug or placebo in a double blind fashion. Restenosis was defined as a 50% lesion. Patients underwent late angiography either at 6 months or sooner if clinically indicated. RESULTS: Both G were similar to age > 70 years (A = 7% vs B = 4%-p = NS), sex (A = 13% vs B = 11%-p = NS), stable angina (A = 43% vs B = 51%), unstable angina (A = 57% vs B = 49%-p = NS) and single vessel (A = 91% vs B = 87%-p = NS) or multivessel (A = 9% vs B = 13%-p = NS) PTCA. We studied 39/44 (89%) patients in GA and 43/45 (96%) in GB (p = NS). We observed restenosis in 17/39 (43%) in GA and 16/43 (37%) in GB (p = NS). The restenosis rate per lesion was 39% in GA and 31% in GB (p = NS). CONCLUSION: Diltiazem was ineffective in the prevention of restenosis following PTCA.