Citotoxicidade e genotoxicidade de nanotubos de carbono

There are many controversies regarding the cyto- and genotoxicity of carbon nanotubes (CNTs). In this work, we discuss that many of the incongruous arguments are probably associated with the poor physical-chemical characterization of the CNT samples used in many publications. This manuscript presents examples of carbon nanostructures observed under high resolution electron microscopy that can be found in typical CNT samples, and shows which roles in cyto- and genotoxicity need to be better investigated. Issues concerning chemical treatment are addressed and examples of misunderstandings that can occur during the studies of cyto- and genotoxicity of CNT samples are given.

A high-resolution Holocene record on the Southern Brazilian shelf: Paleoenvironmental implications

A high-resolution, multi-proxy record has been used to determine the environmental changes during the Holocene on the southern Brazilian shelf Present oceanographic conditions reveal wind and freshwater input as the determinants of short-term productivity changes in the study area. Magnetic susceptibility and grain-size variations, together with proxies of productivity (organic carbon, carbon accumulation rate, Ba, Sr, and Ca content, Ba/Al, Ba/Ti, and Al/Ti ratios) were analyzed and compared with proxies of redox condition (V/Ti ratio), terrigenous input (Fe/Ca and Ti/Ca ratios), as well as other Element/Ti ratios, to evaluate the paleoceanographic and paleoclimatic changes over the period. The core covers a time interval of about 7650 years, with sedimentation rates varying from 0.025 to 0.250 cm a(-1), which represent time intervals of between 8 and 80 a per sample. There is a clear change in the sedimentation rate at about 2800 B.P. All grain-size and elemental results indicate the occurrence of conspicuous changes between 5200 and 5000 cal. B.P., as well as between 3000 and 2800 cal. B.P. A comparison of the results with the palynological information available from the adjacent continental areas suggests that the sedimentary changes in this last interval may be correlated with the onset of modern climatic conditions in South America, and especially, with the onset of the Plata Plume Water, a water mass that carries cold, less saline waters towards the north. However, minor changes are observed at ca. 1500 B.P. and are correlated with an increase in the atmospheric humidity. Furthermore, a time-series analysis undertaken using several proxies indicated the occurrence of Sub-Milankovitch cycles, which may be compared with those reported worldwide. (C) 2008 Elsevier Ltd and INQUA. All rights reserved.

In vitro effects of Er,Cr:YSGG laser on dentine hypersensitivity. Dentine permeability and scanning electron microscopy analysis

The aim of the present study was to determine clinical parameters for the use of Er,Cr:YSGG laser in the treatment of dentine hypersensitivity. Two antagonist areas were determined as control and experimental areas for irradiation in 90 premolar roots. Each surface was conditioned with 24% EDTA (sub-group 1) and 35% phosphoric acid (sub-group 2) and irradiated with the following settings: 1) Er:YAG, 60 mJ, 2 Hz, defocused; groups 2 to 9: irradiation with Er,Cr:YSGG laser, 20 Hz, Z6 tip, 0% of air and water: 2) Er,Cr:YSGG 0.25 W; 3) 0.5 W; 4) 0.75 W; 5) 1.0 W; 6) 1.25 W, 7) 1.50 W, 8) 2 W; 9) 2 W. After irradiation, samples were immersed in methylene blue solution and included in epoxy resin to obtain longitudinal cuts. The images were digitalized and analyzed by computer software. Although the samples irradiated with Er:YAG laser showed less microleakage, sub-group 1 showed differences between the groups, differing statistically from groups 3, 6, and 9. The results of sub-group 2 showed that the mean values of Er:YAG samples showed a negative trend, however, no differences were detected between the groups. For scanning electron microscopy analysis, dentine squares were obtained and prepared to evaluate the superficial morphology. Partial closure of dentinal tubules was observed after irradiation with Er:YAG and Er,Cr:YSGG laser in the 0.25 and 0.50 W protocols. As the energy densities rose, open dentinal tubules, carbonization and cracks were observed. It can be concluded that none of the parameters were capable of eliminating microleakage, however, clinical studies with Er:YAG and Er,Cr:YSGG lasers should be conducted with the lowest protocols in order to determine the most satisfactory setting for dentine hypersensitivity.

Redescription of the larva of Amblyomma oblongoguttatum Koch, 1844 (Acari: Ixodidae) by light and scanning electron microscopy

The larval stage of Amblyomma oblongoguttatum Koch is redescribed using optical and scanning electron microscopy. Unfed larvae were obtained from a colony of A. oblongoguttatum originated from engorged females collected on domestic pigs from Monte Negro municipally (10 degrees 29'S, 63 degrees 32'W), State of Rondonia, Western Amazon, Brazil. Several characters are presented including the chaetotaxy of the idiosoma, palpi and Haller's organ, as well as morphological features of the idiosoma, gnathosoma and legs. In addition, the porotaxy (topographical and numerical patterns of integumentary structures) were presented by using a new nomenclature recently proposed. The chaetotaxy of the larvae of A. oblongoguttatum, in general, is similar to other Neotropical Amblyomma species. Three types of integumentary structures were observed on the idiosoma: lyrifissures, small glands, and large wax glands. Topographic and numerical patterns of the integumentary structures consisted of 5 pairs of large wax glands (1 dorsal/4 ventral), 24 pairs of lyrifissures (11 dorsal/13 ventral), and 49 pairs of small glands (28 dorsal/21 ventral). These topographic and numerical patterns found for A. oblongoguttatum show only minor differences when compared with patterns of other Amblyomma larvae, however, a few key features can be used for identification of these species.

Metallicities for six nearby open clusters from high-resolution spectra of giant stars [Fe/H] values for a planet search sample

We present a study of the stellar parameters and iron abundances of 18 giant stars in six open clusters. The analysis was based on high-resolution and high-S/N spectra obtained with the UVES spectrograph (VLT-UT2). The results complement our previous study where 13 clusters were already analyzed. The total sample of 18 clusters is part of a program to search for planets around giant stars. The results show that the 18 clusters cover a metallicity range between -0.23 and +0.23 dex. Together with the derivation of the stellar masses, these metallicities will allow the metallicity and mass effects to be disentangled when analyzing the frequency of planets as a function of these stellar parameters.

Insertional translocation of 15q25-q26 into 11p13 and duplication at 8p23.1 characterized by high resolution arrays in a boy with congenital malformations and aniridia

We report on a boy presenting submucous cleft palate, hydronephrosis, ventriculoseptal defect, aniridia, and developmental delay. Additional material on 11p13 was cytogenetically visible and array analyses identified a duplicated segment on 15q25-26 chromosome region; further, array analyses revealed a small deletion (49?kb) at 11p13 region involving the ELP4 gene and a duplication at 8p23.1. Results were confirmed with both molecular and molecular cytogenetics techniques. Possibilities for etiological basis of clinical phenotype are discussed. (c) 2012 Wiley Periodicals, Inc.

Texture analysis of high resolution MRI allows discrimination between febrile and afebrile initial precipitating injury in mesial temporal sclerosis

A computational pipeline combining texture analysis and pattern classification algorithms was developed for investigating associations between high-resolution MRI features and histological data. This methodology was tested in the study of dentate gyrus images of sclerotic hippocampi resected from refractory epilepsy patients. Images were acquired using a simple surface coil in a 3.0T MRI scanner. All specimens were subsequently submitted to histological semiquantitative evaluation. The computational pipeline was applied for classifying pixels according to: a) dentate gyrus histological parameters and b) patients' febrile or afebrile initial precipitating insult history. The pipeline results for febrile and afebrile patients achieved 70% classification accuracy, with 78% sensitivity and 80% specificity [area under the reader observer characteristics (ROC) curve: 0.89]. The analysis of the histological data alone was not sufficient to achieve significant power to separate febrile and afebrile groups. Interesting enough, the results from our approach did not show significant correlation with histological parameters (which per se were not enough to classify patient groups). These results showed the potential of adding computational texture analysis together with classification methods for detecting subtle MRI signal differences, a method sufficient to provide good clinical classification. A wide range of applications of this pipeline can also be used in other areas of medical imaging. Magn Reson Med, 2012. (c) 2012 Wiley Periodicals, Inc.

Qualitative study of young, adult, and aged wistar rats temporomandibular synovial membrane employing light, scanning, and transmission electron microscopy

The aim of this study was to analyze the rat temporomandibular joint (TMJ) synovial membrane at different ages using light, scanning, and transmission electron microscopy. Under light microscopic analysis, the TMJ structures were observed such as condyle, capsule, disk, the synovial membrane collagen type, and cells distribution. In the scanning electron microscopy, the synovial membrane surface exhibited a smooth aspect in young animals and there was an increase with ageing in the number of folds. The transmission electron microscopic analysis showed more synoviocytes in the synovial layer in the young group and still a great number of vesicles and cisterns dilation of rough endoplasmic reticulum in the aged group. In the three groups, a dense layer of collagen fibers in the synovial layer and cytoplasmic extensions were clearly seen. It was possible to conclude that synovial membrane structures in aged group showed alterations contributing to the decrease in joint lubrication and in the sliding between disk and joint surfaces. These characteristic will reflect in biomechanics of chewing, and may cause the TMJ disorders, currently observed in clinical processes. Microsc. Res. Tech. (c) 2012 Wiley Periodicals, Inc.

Processing of high resolution magic angle spinning spectra of breast cancer cells by the filter diagonalization method

Proton nuclear magnetic resonance (H-1 NMR) spectroscopy for detection of biochemical changes in biological samples is a successful technique. However, the achieved NMR resolution is not sufficiently high when the analysis is performed with intact cells. To improve spectral resolution, high resolution magic angle spinning (HR-MAS) is used and the broad signals are separated by a T-2 filter based on the CPMG pulse sequence. Additionally, HR-MAS experiments with a T-2 filter are preceded by a water suppression procedure. The goal of this work is to demonstrate that the experimental procedures of water suppression and T-2 or diffusing filters are unnecessary steps when the filter diagonalization method (FDM) is used to process the time domain HR-MAS signals. Manipulation of the FDM results, represented as a tabular list of peak positions, widths, amplitudes and phases, allows the removal of water signals without the disturbing overlapping or nearby signals. Additionally, the FDM can also be used for phase correction and noise suppression, and to discriminate between sharp and broad lines. Results demonstrate the applicability of the FDM post-acquisition processing to obtain high quality HR-MAS spectra of heterogeneous biological materials.

Determination of chlorine in food samples via the AlCl molecule using high-resolution continuum source molecular absorption spectrometry in a graphite furnace

Determination of chlorine using the molecular absorption of aluminum mono-chloride (AlCl) at the 261.418 nm wavelength was accomplished by high-resolution continuum source molecular absorption spectrometry using a transversely heated graphite tube furnace with an integrated platform. For the analysis. 10 mu L of the sample followed by 10 mu L of a solution containing Al-Ag-Sr modifier, (1 g L-1 each), were directly injected onto the platform. A spectral interference due to the use of Al-Ag-Sr as mixed modifier was easily corrected by the least-squares algorithm present in the spectrometer software. The pyrolysis and vaporization temperatures were 500 degrees C and 2200 degrees C, respectively. To evaluate the feasibility of a simple procedure for the determination of chlorine in food samples present in our daily lives, two different digestion methods were applied, namely (A) an acid digestion method using HNO3 only at room temperature, and (B) a digestion method with Ag, HNO3 and H2O2, where chlorine is precipitated as a low-solubility salt (AgCl), which is then dissolved with ammonia solution. The experimental results obtained with method B were in good agreement with the certified values and demonstrated that the proposed method is more accurate than method A. This is because the formation of silver chloride prevented analyte losses by volatilization. The limit of detection (LOD, 3 sigma/s) for Cl in methods A and B was 18 mu g g(-1) and 9 mu g g(-1), respectively, 1.7 and 3.3 times lower compared to published work using inductively coupled plasma optical emission spectrometry, and absolute LODs were 2.4 and 1.2 ng, respectively. (C) 2012 Elsevier B.V. All rights reserved.

Connecting accuracy of interchanged prosthetic abutments to different dental implants using scanning electron microscopy

The present study evaluated the interchangeability of prosthetic components for external hexagon implants by measuring the precision of the implant/abutment (I/A) interface with scanning electron microscopy. Ten implants for each of three brands (SIN, Conexão, Neodent) were tested with their respective abutments (milled CoCr collar rotational and non-rotational) and another of an alternative manufacturer (Microplant) in randomly arranged I/A combinations. The degree of interchangeability between the various brands of components was defined using the original abutment interface gap with its respective implant as the benchmark dimension. Accordingly, when the result for a given component placed on an implant was equal to or smaller then that gap measured when the original component of the same brand as the implant was positioned, interchangeability was considered valid. Data were compared with the Kruskal-Wallis test at 5% significance level. Some degree of misfit was observed in all specimens. Generally, the non-rotational component was more accurate than its rotational counterpart. The latter samples ranged from 0.6-16.9 µm, with a 4.6 µm median; and the former from 0.3-12.9 µm, with a 3.4 µm median. Specimens with the abutment and fixture from Conexão had larger microgap than the original set for SIN and Neodent (p<0.05). Even though the latter systems had similar results with their respective components, their interchanged abutments did not reproduce the original accuracy. The results suggest that the alternative brand abutment would have compatibility with all systems while the other brands were not completely interchangeable.

Comparative study by computed radiography, histology, and scanning electron microscopy of the articular cartilage of normal goats and in chronic infection with caprine arthritis-encephalitis virus

In the northeast of Brazil, caprine arthritis-encephalitis (CAE) is one of the key reasons for herd productivity decreasing that result in considerable economic losses. A comparative study was carried out using computed radiography (CR), histological analysis (HA), and scanning electronic microscopy (SEM) of the joints of CAE infected and normal goats. Humerus head surface of positive animals presented reduced joint space, increased bone density, and signs of degenerative joint disease (DJD). The carpal joint presented no morphological alterations in CR in any of the animals studied. Tarsus joint was the most affected, characterized by severe DJD, absence of joint space, increased periarticular soft tissue density, edema, and bone sclerosis. Histological analysis showed chronic tissue lesions, complete loss of the surface zone, absence of proteoglycans in the transition and radial zones and destruction of the cartilage surface in the CAE positive animals. Analysis by SEM showed ulcerated lesions with irregular and folded patterns on the joint surface that distinguished the limits between areas of normal and affected cartilage. The morphological study of the joints of normal and CAE positive goats deepened understanding of the alteration in the tissue bioarchitecture of the most affected joints. The SEM finding sustained previous histological reports, similar to those found for rheumatoid arthritis, suggesting that the goat infected with CAE can be considered as a potential model for research in this area.

The aplication of land use and nighttime lights on the development of high-resolution emission inventories for South America

In this paper, nighttime light data are suggested as a proxy for spatial distribution of vehicles running in urban and nearby areas. Nighttime lights focus on human activities, in contrast to traditional Earth observing systems that focus on natural systems. It is the human activity being visible in the form of brightness of nocturnal lights. Two available nighttime lights dataset were used in this work. The first one was provided by the U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS), henceforth, DMSO-OLS. The second one is the NASA-NOAA Suomi National Polar-orbiting Polar-orbiting Partnership (NPP) satellite, henceforth, Suomi-NPP. To validate the new proposed methodology, hundreds of urban areas of South America were analyzed in a high degree of resolution. The results of this study showed that night-time lights are very well correlated with vehicle fleet, population, and impervious surfaces but with strong spatial variability. The results of this study suggest a better understanding of the human activities in the context of a vehicular-based city conception.

A complete CMOS UWB timed-array transmitter with a 3D Vivaldi antenna array for electronic high-resolution beam spatial scanning

We present a new Ultra Wide Band (UWB) Timed- Array Transmitter System with Beamforming capability for high-resolution remote acquisition of vital signals. The system consists of four identical channels, where each is formed of a serial topology with three modules: programmable delay circuit (PDC or τ), a novel UWB 5th Gaussian Derivative order pulse generator circuit (PG), and a planar Vivaldi antenna. The circuit was designed using 0.18μm CMOS standard process and the planar antenna array was designed with filmconductor on Rogers RO3206 substrate. Spice simulations results showed the pulse generation with 104 mVpp amplitude and 500 ps width. The power consumption is 543 μW, and energy consumption 0.27 pJ per pulse using a 2V power supply at a pulse repetition rate (PRR) of 100 MHz. Electromagnetic simulations results, using CST Microwave (MW) Studio 2011, showed the main lobe radiation with a gain maximum of 13.2 dB, 35.5º x 36.7º angular width, and a beam steering between 17º and -11º for azimuthal (θ) angles and 17º and -18º for elevation (φ) angles at the center frequency of 6 GHz