Nanoscale switching characteristics of nearly tetragonal BiFeO3 thin films

We have investigated the nanoscale switching properties of strain-engineered BiFeO(3) thin films deposited on LaAlO(3) substrates using a combination of scanning probe techniques. Polarized Raman spectral analysis indicates that the nearly tetragonal films have monoclinic (Cc) rather than P4mm tetragonal symmetry. Through local switching-spectroscopy measurements and piezoresponse force microscopy, we provide clear evidence of ferroelectric switching of the tetragonal phase, but the polarization direction, and therefore its switching, deviates strongly from the expected (001) tetragonal axis. We also demonstrate a large and reversible, electrically driven structural phase transition from the tetragonal to the rhombohedral polymorph in this material, which is promising for a plethora of applications.

Effect of platform switching on peri-implant bone levels: a randomized clinical trial

The concept of platform switching has been introduced to implant dentistry based on observations of reduced peri-implant bone loss. However, randomized clinical trials are still lacking. This study aimed to test the hypothesis that platform switching has a positive impact on crestal bone-level changes.

Open or submerged healing of implants with platform switching: a randomized, controlled clinical trial

The temporal pattern of bone-level alterations in conventionally restored implants is dependent upon healing mode (open or submerged). This study examined the influence of healing on marginal bone levels at implants with a medium-rough surface including the implant collar and a clearance-fit implant-abutment connection restored according to a platform-switching concept.

The causal effect of switching to second-line ART in programmes without access to routine viral load monitoring

We examined the effect of switching to second-line antiretroviral therapy (ART) on mortality in patients who experienced immunological failure in ART programmes without access to routine viral load monitoring in sub-Saharan Africa.

Redox-Switching in a Viologen-type Adlayer: An Electrochemical Shell-Isolated Nanoparticle Enhanced Raman Spectroscopy Study on Au(111)-(1 x 1) Single Crystal Electrodes

We reported the first application of in situ shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) to an interfacial redox reaction under electrochemical conditions. We construct gap-mode sandwich structures composed of a thiol-terminated HS-6V6H viologen adlayer immobilized on a single crystal Au(111)-(1x1) electrode and covered by Au(60 nm)@SlO(2) core shell nanoparticles acting as plasmonic antennas. We observed high-quality, potential-dependent Raman spectra of the three viologen species V(2+),V(+center dot) and V(0) on a well-defined Au(111) substrate surface and could map their potential-dependent evolution. Comparison with experiments on powder samples revealed an enhancement factor of the nonresonant Raman modes of similar to 3 x 10(5), and up to 9 x 10(7) for the resonance modes. The study illustrates the unique capability of SHINERS and its potential in the entire field of electrochemical surface science to explore structures and reaction pathways on well-defined substrate surfaces, such as single crystals, for molecular, (electro-)- catalytic, bioelectrochemical systems up to fundamental double layer studies at electrified solid/liquid interfaces.

Dual-loop circuits in postoperative atrial macro re-entrant tachycardias

Background Patients late after open-heart surgery may develop dual-loop reentrant atrial arrhythmias, and mapping and catheter ablation remain challenging despite computer-assisted mapping techniques. Objectives The purpose of the study was to demonstrate the prevalence and characteristics of dual-loop reentrant arrhythmias, and to define the optimal mapping and ablation strategy. Methods Fourty consecutive patients (mean age 52+/-12 years) with intra-atrial reentrant tachycardia (IART) after open-heart surgery (with an incision of the right atrial free wall) were studied. Dual-loop IART was defined as the presence of two simultaneous atrial circuits. Following an abrupt tachycardia change during radiofrequency (RF) ablation, electrical disconnection of the targeted reentry isthmus from the remaining circuit was demonstrated by entrainment mapping. Furthermore, the second circuit loop was localized using electroanatomic mapping and/or entrainment mapping. Results Dual-loop IART was demonstrated in 8 patients (20%, 5 patients with congenital heart disease, 3 with acquired heart disease). Dual-loop IART included an isthmus-dependant atrial flutter combined with a reentry related to the atriotomy scar. The diagnosis of dual-loop IART required the comparison of entrainment mapping before and after tachycardiamodification. Overall, 35 patients had successful RF ablation (88%). Success rates were lower in patients with dual-loop IART than in patient without dual-loop IART. Ablation failures in 3 patients with dual-loop IART were related to the inability to properly transect the second tachycardia isthmus in the right atrial free wall. Conclusions Dual-loop IART is relatively common after heart surgery involving a right atriotomy. Abrupt tachycardia change and specific entrainment mapping maneuvers demonstrate these circuits. Electroanatomic mapping appears to be important to assist catheter ablation of periatriotomy circuits.

[No rebound psychosis in a case of switching from clozapine to quetiapine]

OBJECTIVE: After rapid discontinuation of clozapine treatment rebound psychosis have been reported. Preexposure of D (2) receptors to clozapine may alter their affinity to endogenous dopamine. Clozapine withdrawal may also lead dysfunctional NMDA-receptors to cause dopamine release in the striatum. METHOD: We report a case of a schizophrenic patient treated with clozapine 200 mg and aripiprazole 15 mg per day. After rapid clozapine discontinuation we added quetiapine up to 700 mg daily. RESULTS: No rebound psychosis occurred. Even ten weeks after switching to quetiapine the patient's condition remained stable in the Brief Psychiatric Rating Scale. CONCLUSIONS: The combination of aripiprazole and quetiapine seemed to control supersensitivity effects at the D (2) receptor after clozapin withdrawal in this case.