RESUMO
We revisit the Fabry-Perot (FP) reflectivity method to measure optical indices in the mid-infrared spectrum. This simple approach can be readily implemented using a standard Fourier transform infrared spectrometer. Measuring samples with multiple heights allows for enhanced precision of the measurement, making the FP method consistent in values and uncertainties with more advanced ellipsometric measurements. An extensive discussion about experimental errors is carried out. Results between 4 and 12 µm for AlInAs, n-doped InGaAs, and InP, which are the most standard materials for quantum cascade lasers, are given.
RESUMO
Quantum cascade detectors (QCDs) are devices operating at zero external bias with a low dark-current. They show linear detection and high saturation intensities, making them suitable candidates for heterodyne detection in long-wave infrared (LWIR) free space optical communication systems. We present an approach to mitigate the performance limitation at long wavelengths, by a comparison of similar single and multi-period QCDs for optimizing their responsivity and noise behaviour. Our InGaAs/InAlAs/InP ridge QCDs are designed for operation at λ = 9.124 µm. Optical waveguide simulations support the accurate optical characterization. A detailed device analysis reveals room-temperature responsivities of 111 mA/W for the 15-period and 411 mA/W for the single-period device.
RESUMO
Nanoparticulate materials are produced by industrial processing or engineered for specific biomedical applications. In both cases, their contact with the human body may lead to adverse reactions. Most of the published papers so far have focused on the cytotoxic effects of nanoparticles (NPs). Instead, the present in vitro study investigates the effect of different types of NP on key components of the host response such as clot formation and the inflammatory cells. The different NPs were pre-conditioned with platelet-rich human plasma for 30 min and then incubated with the blood mononuclear cells for 20 hours. The potential of the different NPs to induce clot formation, platelet activation and monocyte/macrophage differentiation was assessed by morphological analysis, immunocytochemistry and biochemical assays. The data showed that nanoparticulate materials based on antimony, silver and nickel were capable of promoting the polymerization of fibrin and the aggregation and fragmentation of platelets, leading to a moderately activated monocyte phenotype. This process was more pronounced in the case of antimony- and silver-based NPs that share a similar size and round-shaped morphology. Conversely, NPs of cobalt, titanium and iron appeared to stimulate cells to acquire a macrophage phenotype able to secrete higher levels of tumour necrosis factor alpha, a pro-inflammatory cytokine. Therefore, the present study provides clear indications about the subtle and adverse effects that the invasion of these materials may produce in the cardiovascular system and in vital organs.
Assuntos
Nanopartículas/química , Nanotecnologia/métodos , Adulto , Antimônio/química , Bioquímica/métodos , Citocinas/metabolismo , Feminino , Humanos , Imuno-Histoquímica/métodos , Inflamação/tratamento farmacológico , Macrófagos/metabolismo , Masculino , Pessoa de Meia-Idade , Monócitos/citologia , Níquel/química , Fenótipo , Ativação Plaquetária , Prata/química , Fatores de Tempo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
A second-generation cephalosporin (cephotaxime) with a marked resistance to beta-lactamase, a very broad spectrum, and remarkably low renal toxicity was used to treat 47 patients with respiratory, urinary and other infections. The results were excellent in 89.2% and good in 8.5%. The antibiotic proved effective even against germs that are usually resistant to cephalosporins (Pseudomonas, Proteus, Serratia and Enterobacteriaceae). Bacteriuria disappeared in all cases of urinary infection. Local and general tolerance was excellent in all cases but one. Renal tolerance was also excellent in patients with chronic renal failure, for whom the daily dose can be usefully reduced and a check on renal function should be kept.
