Rashba Spin Splitting Limiting the Application of 2D Halide Perovskites for UV-Emitting Devices.

Layered lead halide perovskites have attracted much attention as promising materials for a new generation of optoelectronic devices. To make progress in applications, a full understanding of the basic properties is essential. Here, we study 2D-layered (BA)2PbX4 by using different halide anions (X = I, Br, and Cl) along with quantum confinement. The obtained cell parameter evolution, supported by experimental measurements and theoretical calculations, indicates strong lattice distortions of the metal halide octahedra, breaking the local inversion symmetry in (BA)2PbCl4, which strongly correlates with a pronounced Rashba spin-splitting effect. Optical measurements reveal strong photoluminescence quenching and a drastic reduction in the PL quantum yield in this larger band gap compound. We suggest that these optical results are closely related to the appearance of the Rashba effect due to the existence of a local electric dipole. The results obtained in ab initio calculations showed that the (BA)2PbCl4 possesses electrical polarization of 0.13 µC/cm2 and spin-splitting energy of about 40 meV. Our work establishes that local octahedra distortions induce Rashba spin splitting, which explains why obtaining UV-emitting materials with high PLQY is a big challenge.

Comparing the Cubic and Tetragonal Phases of MAPbI3 at Room Temperature.

Stability and maintenance of the crystal structure are the main drawbacks of the application of organic-inorganic perovskites in photovoltaic devices. The ΔT = 62 K robust shift of the structural phase transition observed here allows us to conduct a comprehensive study at room temperature of the tetragonal versus cubic phase on MAPbI3. The absence of the shift in the cubic transition for all-inorganic CsPbI3 samples confirms the importance of both orientation and dynamics of the organic cations. Our results provide a unique opportunity to evaluate the physical properties of both cubic and tetragonal phases of MAPbI3 at the same temperature, eliminating different phonon effects as possible causes for different properties. Besides higher electrical resistivity, the perovskite cubic phase presents a faster charge carrier lifetime than the tetragonal phase and partial PL quenching, pointing toward increased trap-assisted nonradiative recombination. The light absorption coefficient in the cubic phase is larger than the absorption in the tetragonal phase in the green region.

Ultrafast fabrication of thermally stable protein-coated silver iodide nanoparticles for solid-state superionic conductors.

Solid-state ionic conductor is an essential and critical part of electrochemical devices such as batteries and sensors. Nano-sized silver iodide (AgI) is the most promising ionic conductor due to its superionic conductivity at room temperature. In recent years, proteins have been used as organic templates to obtain high-performance solid-state ionic conductors as well as to extend their applications in a biosensor. Here, we report the unprecedented ultrafast synthesis of thermally stable protein-coated AgI nanoparticles (NPs) through the photo-irradiation method for solid-state electrolyte. The synthesis was performed using a hyperthermostable bacterial ß-glucosidase. The protein-coated AgI NPs with an approximate diameter of 13 nm showed that the controllable transition from the α- to ß-/γ-phase was drastically suppressed down to 41 °C in the cooling process. After drying, the product represents a thermally stable organic-inorganic hybrid system with superionic conductivity. It is noteworthy that the superionic conductivity (σ ˜ 0.14 S/cm at 170 °C) of thermally stable protein-coated AgI NPs is maintained during several thermal cycles (25-170 °C). To our knowledge, this is the first report showing the diffusion of mobile Ag+ ions on the surface of the AgI NPs through a protein matrix. The facile synthesis method and high performance of the protein-coated AgI NPs may provide a latent application in the mass production of nanobatteries and other technological applications.

Foreign body reaction associated with PET and PET/chitosan electrospun nanofibrous abdominal meshes.

Electrospun materials have been widely explored for biomedical applications because of their advantageous characteristics, i.e., tridimensional nanofibrous structure with high surface-to-volume ratio, high porosity, and pore interconnectivity. Furthermore, considering the similarities between the nanofiber networks and the extracellular matrix (ECM), as well as the accepted role of changes in ECM for hernia repair, electrospun polymer fiber assemblies have emerged as potential materials for incisional hernia repair. In this work, we describe the application of electrospun non-absorbable mats based on poly(ethylene terephthalate) (PET) in the repair of abdominal defects, comparing the performance of these meshes with that of a commercial polypropylene mesh and a multifilament PET mesh. PET and PET/chitosan electrospun meshes revealed good performance during incisional hernia surgery, post-operative period, and no evidence of intestinal adhesion was found. The electrospun meshes were flexible with high suture retention, showing tensile strengths of 3 MPa and breaking strains of 8-33%. Nevertheless, a significant foreign body reaction (FBR) was observed in animals treated with the nanofibrous materials. Animals implanted with PET and PET/chitosan electrospun meshes (fiber diameter of 0.71 ± 0.28 µm and 3.01 ± 0.72 µm, respectively) showed, respectively, foreign body granuloma formation, averaging 4.2-fold and 7.4-fold greater than the control commercial mesh group (Marlex). Many foreign body giant cells (FBGC) involving nanofiber pieces were also found in the PET and PET/chitosan groups (11.9 and 19.3 times more FBGC than control, respectively). In contrast, no important FBR was observed for PET microfibers (fiber diameter = 18.9 ± 0.21 µm). Therefore, we suggest that the reduced dimension and the high surface-to-volume ratio of the electrospun fibers caused the FBR reaction, pointing out the need for further studies to elucidate the mechanisms underlying interactions between cells/tissues and nanofibrous materials in order to gain a better understanding of the implantation risks associated with nanostructured biomaterials.

Selective contrast echocardiography in percutaneous transluminal septal myocardial ablation in an elderly patient with left ventricular concentric hypertrophy.

We report an elderly patient, with hypertension and left ventricular concentric hypertrophy with sigmoid shape of the septum, who presented an unsatisfactory response to medical treatment and who was successfully submitted to myocardial contrast echocardiography-guided percutaneous transluminal septal myocardial ablation.

Efeitos da torçäo do cordäo espermático sobre os parâmetros seminais do testículo contralateral em ratos pré-puberais / Seminal effects on contralateral testis following spermatic cord torsion in prepubertal rats

A torçäo do cordäo espermático é muito discutida principalmente quando ao seu efeito contralateral e à influência do testículo isquêmico. Tem sido bastante estudada em animais adultos embora, no homem, incida mais na infância e adolescência. O estudo tem o objetivo de avaliar o testículo contralateral de ratos pré-puberais submetidos à torçäo do cordäo espermático, mantendo-se ou näo o testículo torcido. Foram utilizados 120 ratos Wistar, com idade de 35 dias, divididos em 3 grupos: anestesia, simulado e torçäo. A avaliaçäo foi feita aos 70 ou 105 dias de vida, estudando-se o peso testicular, a motilidade e a concentraçäo dos espermatozóides. O sêmen do rato foi obtido pela microaspiraçäo do túbulo seminífero na cauda do epidídimo. A motilidade dos espermatozóides diminuiu nos animais maduros quando o testículo torcido foi mantido. A concentraçäo de espermatozóides foi sempre superior nos animais com idade de 105 dias, embora näo tenha sido significativa quando o testículo torcido foi retirado. O peso do testículo näo mostrou diferença em relaçäo ao procedimento ou às diferentes idades. A avaliaçäo desses animais em idades jovens, de aproximadamente 70 dias, näo é recomendável pois näo representa a sua maturidade sexual completa. A obtençäo de esperma do túbulo seminífero através da microaspiraçäo permitiu avaliar o potencial reprodutivo do rato, de acordo com os parâmetros seminais estudados

Enterocistoplastias / Enterocistoplasty

Foram estudadas 14 criancas submetidas as enterocistoplastia (ECP) no Servico de Cirurgia Pediatrica-Setor de Urologia- do Hospital Infantil Joana de Gusmao em Florianopolis. O diagnostico dos pacientes foi mielodisplasia (6 casos), valvula de uretra posterior, extrofia vesical, reflexo vesicoureteral e neoplasia. A ECP foi indicada como desderivacao, reconstrucao do tato urinario, ampliacao vesical e tratamento de incontinencia urinaria. O resultado da ECP foi determinado como satisfatorio e insatisfatorio por 3 aspectos: a condicao de continencia, o trato urinario superior e a capacidade vesical. Nao houve resultado ruim ou obito