Characterization of microfabricated probes for combined atomic force and high-resolution scanning electrochemical microscopy

A combined atomic force and scanning electrochemical microscope probe is presented. The probe is electrically insulated except at the very apex of the tip, which has a radius of curvature in the range of 10-15 nm. Steady-state cyclic voltammetry measurements for the reduction of Ru(NH3)6Cl3 and feedback experiments showed a distinct and reproducible response of the electrode. These experimental results agreed with finite element simulations for the corresponding diffusion process. Sequentially topographical and electrochemical studies of Pt lines deposited onto Si3N4 and spaced 100 nm apart (edge to edge) showed a lateral electrochemical resolution of 10 nm.     

Influence of fiber optic probe geometry on the applicability of inverse models of tissue reflectance spectroscopy: computational models and experimental measurements

Accurate recovery of tissue optical properties from in vivo spectral measurements is crucial for improving the clinical utility of optical spectroscopic techniques. The performance of inversion algorithms can be optimized for the specific fiber optic probe illumination-collection geometry. A diffusion-theory-based inversion method has been developed for the extraction of tissue optical properties from the shape of normalized tissue diffusion reflectance spectra, specifically tuned for a fiber probe that comprises seven hexagonally close-packed fibers. The central fiber of the probe goes to the spectrometer as the detecting fiber, and the surrounding six outer fibers are connected to the white-light source as illumination fibers. The accuracy of the diffusion-based inversion algorithm has been systematically assessed against Monte Carlo (MC) simulation as a function of probe geometry and tissue optical property combinations. By use of this algorithm, the spectral absorption and scattering coefficients of normal and cancerous tissue are efficiently retrieved. Although there are significant differences between the diffusion approximation and the MC simulation at short source-detector (SD) separations, we show that with our algorithm the tissue optical properties are well retrieved within the SD separation of 0.5-3 mm that is compatible with endoscopic specifications. The presented inversion method is computationally efficient for eventual real-time in vivo tissue diagnostics application.     

Kinetics and mechanism of the degradation of methyl parathion in aqueous hydrogen sulfide solution: investigation of natural organic matter effects

The kinetics of the transformation of methyl parathion have been investigated in aqueous solution containing reduced sulfur species and small concentrations of natural organic matter (NOM) from different sources such as soil, river, and peat. It was shown that NOM mediates the degradation of methyl parathion in aqueous solutions containing hydrogen sulfide. After evaluating and quantifying the effect of the NOM concentration on the degradation kinetics of methyl parathion in the presence of hydrogen sulfide, it was found that the observed pseudo-first-order reaction rate constants (k(obs)) were proportional to NOM concentrations. The influence of pH on the degradation of methyl parathion in the aqueous solutions containing hydrogen sulfide and NOM has been studied. The rate of degradation of methyl parathion was strongly pH dependent. The results indicate k(obs) with a commercially available humic acid has a maximum value at approximately pH 8.3. Two main reaction mechanisms are identified to dominate the degradation of methyl parathion in aqueous solution containing hydrogen sulfide and NOM based on the products aminomethyl parathion and desmethyl methyl parathion. The two mechanisms are nitro-group reduction and nucleophilic attack at the methoxy-carbon. The reduction of the nitro-group is only observed in the presence of NOM. The results of this study form an important base for the evaluation and interpretation of transformation processes of methyl parathion in the environment.     

Degradation of naled and dichlorvos promoted by reduced sulfur species in well-defined anoxic aqueous solutions

This work examines the reaction of reduced sulfur species (e.g., bisulfide, thiosulfate, thiophenolate) with naled, a registered insecticide, in well-defined anoxic aqueous solutions at 5 degrees C. High concentrations of reduced sulfur species can occur in the porewater of sediments and in anoxic subregions of estuaries. The dominanttransformation product from the reaction of naled with reduced sulfur species is dichlorvos, which indicates that debromination is the major reaction pathway. Dichlorvos is also a registered insecticide which is more toxic than naled. The second-order rate constants for reaction of naled with bisulfide and thiophenolate at 5 degrees C are 10.2 +/- 0.4 M(-1) s(-1) and 27.3 +/- 0.9 M(-1) s(-1), respectively, while the second-order rate constant for the reaction of naled with hydrogen sulfide and thiophenol are not significantly different from zero. The second-order rate constant of the reaction of naled with thiosulfate at 5 degrees C is 5.0 +/- 0.3 M(-1) s(-1). In contrast, the second-order rate constant of the reaction of dichlorvos with bisulfide at 25 degrees C is (3.3 +/- 0.1) x 10(-3) M(-1) s(-1). The activation parameters of the reaction of naled with bisulfide were also determined from the measured second-order rate constants over a temperature range. The results indicate that reduced sulfur species can play a very important role in the transformation of naled and dichlorvos in the coastal marine environment. It can be expected that in the presence of reduced sulfur species, naled is almost immediately transformed into the more toxic dichlorvos, which has an expected half-life of 4 days to weeks.     

Assessment of use of the COBAS AMPLICOR system with BACTEC 12B cultures for rapid detection of frequently identified mycobacteria

The use of the COBAS AMPLICOR System (Roche Molecular Diagnostics, Basel, Switzerland), the only automated system for PCR testing, was evaluated for a rapid identification of mycobacteria with positive BACTEC 12B cultures. Two hundred ninety-six specimens with a growth index of >/=30 were analyzed for the presence of Mycobacterium tuberculosis complex, Mycobacterium avium, and Mycobacterium intracellulare. Compared to traditional methods and provided that samples with PCR inhibition are retested at a 1:10 dilution, the sensitivity and specificity of the COBAS AMPLICOR System with BACTEC 12B cultures were 100 and 98%, respectively. The COBAS AMPLICOR method is rapid and reliable for identifying the most common mycobacteria in cultures.     

Internet Predictions

More than a dozen leading experts give their opinions on where the Internet is headed and where it will be in the next decade in terms of technology, policy, and applications. They cover topics ranging from the Internet of Things to climate change to the digital storage of the future.     

The higher injury risk of abnormal kidneys in blunt renal trauma

In an effort to better understand some of the ethical and legal dilemmas that health professionals face in their daily activities, this study identified and analyzed the opinions and expectations of medical and nursing students at the University of S?o Paulo, Brazil, regarding the autonomy of adolescents in receiving health care services. Over the 1995-1996 period, interviews were done with students in the first and last years of their programs in the School of Medicine and the School of Nursing of the University of S?o Paulo. The results from the first-year students were compared with those of the final-year students. The interview questions dealt with such issues as providing medical care to adolescents when a parent or guardian was not present, adolescents making their own decisions on health care services, the confidentiality of information that adolescents provide, the circumstances in which that information could be given to parents or guardians, and situations where there were conflicts between the decisions of parents and adolescents. Despite variations among the opinions and expectations of the students, the overall results suggest that most of the medical and nursing students do not accept the concept of "health adulthood" or autonomy for adolescents and that the students instead choose to rely on current legal definitions of adulthood.     

Primary pericardial angiosarcoma with multiple lung and a solitary liver metastases: the clinical and anatomicopathological findings

A case of 66-year-old woman with cardiac tamponade and bilateral pulmonary infiltrates is reported. These infiltrates were "pseudonodulars" and confluent. We practice pericardiocentesis and a hemorrhagic fluid is pulled out. Its cytology shown not neoplastic cells. She died and the necropsy shown an angiosarcoma of pericardium with multiple pulmonary and alone hepatic metastases.