An oxygen amperometric gas sensor based on its electrocatalytic reduction in room temperature ionic liquid

A conveniently assembled membrane-free amperometric sensor is proposed for the detection of oxygen in gaseous atmospheres which exploits some profitable properties of room temperature ionic liquids (RTILs), such as their high electrical conductivity, negligible vapour pressure and good thermal stability. The advantages offered by this type of medium were increased by adding small amounts of a further low melting salt bearing a quinone moiety, which allowed the reduction of O-2 to occur through an electrocatalytic pathway taking place at quite lower potentials than those required by its direct reduction. The rate constant (14,160 +/- 370 M-1 s(-1)) of this electrocatalytic process was determined by resorting to linear sweep voltammetric measurements. The performance of this device was assayed under both flowing and static stop-flow conditions on synthetic O-2 + N-2 atmospheres with a controlled oxygen content, which was changed in a wide range (200-10(6) ppm v/v). At room temperature, repeatable (+/- 2.7%) and linearly dependent current signals were recorded, allowing a detection limit of 140 ppm v/v (equivalent to 6.2 x 10(-6) mol of O-2 per L of gaseous atmosphere) to be inferred. At higher temperatures (100 degrees C) a lower detection limit (10 ppm v/v, equivalent to 4.5 x 10(-7) mol of O-2 per L of gaseous atmosphere) could be instead estimated. The possibility of profiting from this sensor for monitoring oxygen under reduced pressure was also assayed, in view of the growing importance attached to the evaluation of residual O-2 in food packaging under vacuum or controlled atmospheres. (C) 2012 Elsevier B.V. All rights reserved

Violência denunciada: ocorrências de maus tratos contra crianças e adolescentes registradas em uma unidade policial

Esse estudo objetiva verificar o perfil da ocorrência de maus-tratos contra crianças e adolescentes. Foram analisados os dados registrados nas ocorrências policiais da Delegacia de Defesa da Mulher de Araçatuba-SP, no ano de 2008, relativos à agressão; relação vítima-agressor; características sociodemográficas de agressores e vítimas e procura das vítimas por serviço de saúde. Dentre as denúncias feitas, houve uma maior prevalência de maus tratos físicos, sendo a residência o local de maior incidência de agressões. Na maioria das vezes, o agressor era a mãe da criança, sendo o motivo não relatado, na maior parte dos casos. Desse modo, podemos delinear o perfil das ocorrências violentas contra criança, contribuindo para a visualização, conhecimento e enfrentamento do problema

An ionic-liquid based probe for the sequential preconcentration from headspace and direct voltammetric detection of phenols in wastewaters

A conveniently assembled probe is here proposed for the electrochemical detection of the phenol index (total volatile phenols) in wastewaters, which exploits some advantageous properties of ionic liquids (ILs), such as their negligible vapor pressure, good electrical conductivity and ability to dissolve a wide range of organic and inorganic compounds. It consists of three Pt wires piercing through a Teflon rod, whose exposed end is coated with an adhesive film of ionic liquid which assured the necessary ionic conductivity between the electrodes while displaying concomitantly good solvent properties. The electrode assembly was exposed to the headspace in equilibrium with wastewater samples for controlled times, until a convenient preconcentration of volatile phenols was achieved. At the end of this step, voltammetric detection was directly performed in situ. The performance of this device was assayed in both phenol synthetic samples and in real wastewaters, after that the preconcentration step was optimized with regard to the effect of pH of the sample, preconcentration time sample and probe temperature and nature of IL. Voltammetric responses characterized by good repeatability (+/- 4%) were recorded, whose height and area depended linearly on the phenol concentration over a wide range (ca. 3 orders of magnitude). The detection limit, estimated for a signal-to-noise ratio of 3 (2 mu M at 20 degrees C and 0.2 mu M at 80 degrees C), was lower than the limit set by the European Community for phenols in wastewaters (ca. 5 mu M). The results found in real samples were in acceptable agreement with those obtained by the 4-aminoantipyrine colorimetric approach which is recommended as the standard method

Occurrence of traumatic dental injury in cases of domestic violence

The purpose of this study was to investigate the prevalence and types of traumatic dental injuries in situations of domestic violence. A coross-sectional study was conducted and data were collected from the police occurrence records to domestic physical aggression between 2001 and 2005. Of the 1,844 subjects who underwent medical evaluation, 15 had information pertaining to traumatic dental injuries. From the medical records, the forensic medical reports completed by the forensic medical experts who examined the victims after the aggression were reviewed and data of individuals with dental injuries (e.g., fractures, luxation and avulsion) were collected. In the selected sample, there was a predominance of individuals with injuries to the head and neck region (38.7%), and the frequency of traumatic dental injuries among all injuries to the head and neck region was 2.0%. The most frequently injured teeth were the maxillary incisors (31.8%), followed by the mandibular incisors (27.3%) and the maxillary canines (9.1%). In 31.8% of the injured teeth, the forensic experts did not specify the nomenclature. Of the dental trauma cases, 59.1% were fractures, 27.2% were luxations and 13.7% were avulsions. In conclusion, domestic violence was an important etiologic factor of traumatic dental injury. The aggression in all cases occurred in the form of punches and slaps. Fracture was the most common type of traumatic dental injury, and the most frequently injured teeth were the incisors.Universidade Estadual Paulista (UNESP) Araçatuba Dental School, Rua José Bonifacio, 1193, Vila Mendonça, 16015-050 Araçatuba, SPUniversidade Estadual Paulista (UNESP) Araçatuba Dental School, Rua José Bonifacio, 1193, Vila Mendonça, 16015-050 Araçatuba, S

Quantitative Analysis of GPR Signals: Transmitted Wavelet, Amplitude Decay, and Sampling-Related Amplitude Distortions

3noWe study the importance of accurately recording signal amplitudes for the quantitative analysis of GPR data sets. Specifically, we measure the peak amplitudes of signals emitted by GPR antennas with different central frequencies and study their amplitude decay with distance, in order to extrapolate the peak amplitude of the wavelet initially transmitted by each antenna. The purpose is to compare the reference and reflected amplitudes in order to accurately estimate the subsurface EM impedance contrasts. Moreover, we study how sampling-related amplitude distortions can affect the quantitative analysis, and subsequently the resulting subsurface models, even in the absence of aliasing effects. The well-known Nyquist–Shannon theorem gives practical lower limits for the sampling rate in order to preserve the spectral content of a digitized signal; however, we show that it does not prevent possible amplitude distortions. In particular, we demonstrate that significant and unrecoverable loss of amplitude information occurs even at sampling rates well above the Nyquist– Shannon threshold. Interpolation may theoretically reduce such amplitude distortions; however, its accuracy would depend on the implemented algorithm and it is not verifiable in real data sets, since the actual amplitude information is limited to the sampled values. Moreover, re-sampling the interpolated signal simply reintroduces the initial problem, when a new sampling rate is selected. Our analysis suggests that, in order to limit the maximum peak amplitude error within 5%, the sampling rate selected during data acquisition must be at least 12 times the signal central frequency, which is higher than the commonly adopted standards.reservedmixedDossi, M.; Forte, Emanuele; Pipan, M.Dossi, M.; Forte, Emanuele; Pipan, M

Sample loading and retrieval by centrifugation in a closed-loop PCR microchip

We report on a novel concept of sample loading for microfluidic devices using a benchtop centrifuge and a magnetically actuated circular closed-loop PCR microchip as a model system. The PCR mixture and the ferrofluid were loaded into a specially designed microchip. The microchip was then placed in an off-the-shelf 50-mL tube and centrifuged. The strong centrifugal force drives the PCR mixture and the ferrofluid into the microchannels of the microchip, and simultaneously expels any trapped microbubbles. PCR was successfully carried out on single and parallel closed-loop PCR microchips. The addition of a few off-chip handling steps allows great simplification of the device design. This new loading concept may be useful for designing robust and low-cost lab-on-a-chip devices because benchtop centrifuges are quite common in most laboratories.Full Tex