Impedance spectroscopy analysis of SnO2 thick-films gas sensors

A careful analysis of the impedance response of SnO2 thick films under vacuum and air atmosphere is reported in the present work. The AC electrical resistance was analyzed and it was shown that it is highly frequency dependent. Different models and its equivalent circuit representation were proposed and carefully analyzed based on the microstructure features of the device. Basically, an interpretation of the frequency dependent resistance was proposed based on the fact that different grains characteristics and junctions exist. These different grains and junctions are the main source of resistance dependent feature. An equivalent circuit model, considering different grain sizes associated with different grain boundary junctions characteristics, was introduced so that a consistent interpretation of the results was possible.

Advancements in the knowledge of induced tooth movement: idiopathic osteosclerosis, cortical bone and orthodontic movement

Movimentar ortodonticamente os dentes por áreas densas do trabeculado ósseo e pelas corticais pode requerer uma redução na intensidade e/ou na concentração das forças aplicadas. em parte, as forças ortodônticas aplicadas são dissipadas e reduzidas pela deflexão óssea que ocorre pelo discreto grau de elasticidade do tecido ósseo em condições de normalidade. Nas áreas de trabeculado denso e nas corticais, essa deflexão deve ser irrisória ou inexistente. Se não houver uma redução na intensidade das forças nessas regiões citadas, toda a força incidirá sobre a estrutura do ligamento periodontal, aumentando o risco de morte dos cementoblastos, hialinização e reabsorções radiculares. Novos trabalhos poderiam avaliar a prevalência dessas consequências em casuísticas selecionadas para essa finalidade, que, assim, deixariam de ser observações aleatórias.

Movement of Heterorhabditis amazonensis and Steinernema arenarium in search of corn fall armyworm larvae in artificial conditions

Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) is considered to be the main pest of maize crops in Brazil. Entomopathogenic nematodes (EPN) may be used to control this pest and exhibit different, unique abilities to search for their hosts. The movement of EPN in relation to S. frugiperda was evaluated. To test for horizontal movement, a styrofoam enclosure filled with sand was divided into segments, nematodes were placed at the entrance to the enclosure and a larva was placed at the end of each division. The same approach was used to evaluate vertical movement; however, PVC pipes were used in this case. In general, the mortality was inversely proportional to the initial distance between host and nematodes. In the vertical displacement test, both nematodes were able to kill the larvae up to a distance of 25 cm. Therefore, the infective juveniles of H. amazonensis and S. arenarium can search out, infect and kill larvae of S. frugiperda at distances of up to 60 cm and 25 cm of horizontal and vertical displacement, respectively.

Grain size effect on the electrical response of SnO2 thin and thick film gas sensors

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and characterization of an equine behaviour chamber and the effects of amitraz and detomidine on spontaneous locomotor activity

This report describes the development of a behaviour chamber and the validation of the chamber to measure locomotor activity of a horse, Locomotor activity was detected by four Mini-beam sensors and recorded on a data logger every 5 min for 22 h. Horses were more active during daytime than in the evening, which was at least partially related to human activity in their surroundings. To validate the ability of the chambers to detect changes in activity, fentanyl citrate and xylazine HCl, agents well-characterized as a stimulant and a depressant, respectively, were administered to five horses. Fentanyl citrate (0.016 mg/kg) significantly increased locomotor activity which persisted for 30 min, Xylazine HCl (1 mg/kg) significantly reduced locomotor activity for 90 min. Amitraz produced a dose-dependent decrease in locomotor activity, lasting 75 min for the 0.05 mg/kg dose, 120 min for the 0.10 mg/kg dose, and 180 min for the 0.15 mg/kg dose, In a separate experiment, yohimbine administration immediately reversed the sedative effect of amitraz, This suggests there is a similarity in the mode of action of amitraz, xylazine and detomidine, as yohimbine acts primarily by blocking central alpha 2-adrenoceptors that are stimulated by agents like xylazine, There was also a significant decrease in locomotor activity following injection of detomidine (0.02, 0.04 and 0.08 mg/kg) for 1.5, 3.5 and 5.0 h, respectively, the locomotor chamber is a useful, sensitive and highly reproducible tool for measuring spontaneous locomotor activity in the horse, which allows investigators to determine an agent's average time of onset, duration and intensity of effect on movement.

Aspects of cathodic stripping voltammetry at the hanging mercury drop electrode and in non-mercury disposable sensors

Cathodic stripping voltammetry (CSV) and accumulation at the hanging mercury drop electrode are reviewed briefly. Proposals in a recent IUPAC technical report are considered. Three recent developments in CSV are discussed: the adaptation of CSV methods developed for use with the hanging mercury drop electrode for use with screen-printed carbon electrodes in disposable sensors, the use of reactive accumulation, and the chemometric use of kinetic methods of determination with pulse methods in CSV.

The effects of anxiety on visual search, movement kinematics, and performance in table tennis: A test of Eysenck and Calvo's processing efficiency theory

Processing efficiency theory predicts that anxiety reduces the processing capacity of working memory and has detrimental effects on performance. When tasks place little demand on working memory, the negative effects of anxiety can be avoided by increasing effort. Although performance efficiency decreases, there is no change in performance effectiveness. When tasks impose a heavy demand on working memory, however, anxiety leads to decrements in efficiency and effectiveness. These presumptions were tested using a modified table tennis task that placed low (LWM) and high (HWM) demands on working memory. Cognitive anxiety was manipulated through a competitive ranking structure and prize money. Participants' accuracy in hitting concentric circle targets in predetermined sequences was taken as a measure of performance effectiveness, while probe reaction time (PRT), perceived mental effort (RSME), visual search data, and arm kinematics were recorded as measures of efficiency. Anxiety had a negative effect on performance effectiveness in both LWM and HWM tasks. There was an increase in frequency of gaze and in PRT and RSME values in both tasks under high vs. low anxiety conditions, implying decrements in performance efficiency. However, participants spent more time tracking the ball in the HWM task and employed a shorter tau margin when anxious. Although anxiety impaired performance effectiveness and efficiency, decrements in efficiency were more pronounced in the HWM task than in the LWM task, providing support for processing efficiency theory.

FRACTAL CHARACTERISTICS OF THE HORIZONTAL MOVEMENT OF WATER IN SOILS

Observed deviations from traditional concepts of soil-water movement are considered in terms of fractals. A connection is made between this movement and a Brownian motion, a random and self-affine type of fractal, to account for the soil-water diffusivity function having auxiliary time dependence for unsaturated soils. The position of a given water content is directly proportional to t(n), where t is time, and exponent n for distinctly unsaturated soil is less than the traditional 0.50. As water saturation is approached, n approaches 0.50. Macroscopic fractional Brownian motion is associated with n < 0.50, but shifts to regular Brownian motion for n = 0.50.

Influence of Orthodontic Dental Movement on the Healing Process of Teeth With Periapical Lesions

The purpose of this study was to histomorphologically evaluate (in dog's teeth) the influence of tooth movement in the healing of chronic periapical lesions. Thirty roots of incisors and premolars of two dogs (1-year-old) were used in this research. After pulpectomy, the root canals remained exposed to the oral environment for 6 months for achievement of periapical lesions. Twenty root canals were biomechanically prepared and received a calcium hydroxide dressing for 14 days before being filled with gutta-percha points and Sealapex sealer. After root canal treatment, some incisors were submitted to orthodontic movement, whereas the other roots remained without orthodontic movement. The orthodontic appliance was removed at 5 months and 15 days after treatment, the dogs were killed 15 days later and the specimens were prepared for histomorphological analysis. The results showed that the orthodontic movement delayed, but did not hinder, the periapical healing process. (J Endod 2006;32:115-119)

Immediate and sustained changes in tongue movement with an experimental palatal Fistula: A case study

Objective: To determine the immediate and longer-term effect(s) on tongue movement following the placement of an experimental opening through a palatal obturator (replicate of subject's prosthesis) worn by an adult male with an unrepaired cleft of the hard and soft palate.Methods: Tongue movements associated with an anterior experimental opening of 20 mm(2) were examined under three conditions: a control condition in which the subject wore the experimental obturator completely occluded, a condition immediately after drilling the experimental openings through the obturator, and a condition after 5 days in which the subject wore the experimental obturator with the experimental opening. An Electromagnetic Articulograph was used for obtaining tongue movements during speech.Results: the findings partly revealed that the immediate introduction of a perturbation to the speech system (experimental fistula) had a temporary effect on tongue movement. After sustained perturbation (for 5 days), the system normalized (going back toward control condition's behavior). Perceptual data were consistent with kinematic tongue movement direction in most of the cases.Conclusions: Although the immediate response can be interpreted as indicative of the subject's attempts to move the tongue toward the opening to compensate for air loss, the findings following a sustained perturbation indicate that with time, other physiological adjustments (such as respiratory adjustments, for example) may help reestablish the requirements of a pressure-regulating system.

Short-term movement and retreat sites of Leptodactylus labyrinthicus (Anura : Leptodactylidae) during the breeding season: A spool-and-line tracking study

Capture/recapture studies significantly increase our knowledge of the natural history of anuran amphibians. Many different methods have been employed in these studies, but a number of new techniques still require experimental validation. During two reproductive seasons in a Cerrado remnant in southeastern Brazil, we investigated the movement patterns and habitat use of the pepper frog, Leptodactylus labyrinthicus, using a spool-and-line device. This low-cost device did not appear to interfere with the activities of the frogs and allowed for constant monitoring, showing precise routes of movement and great predictability of relocations. Both sexes were active at night. During the day, males and females made use of retreat sites under vegetation or in burrows constructed by small- and medium-sized mammals. Males and females did not use standardized routes; there were no significant differences between their movements, and movements were not correlated with body size or environmental conditions. Individuals are able to move further than 100 m per day, a characteristic that may enable this species to colonize or recolonize open areas.

Conductive composites of natural rubber and carbon black for pressure sensors

Composites of natural rubber and carbon black have attracted great interest due to their technological applications. In this work natural rubber (NR) and carbon black (CB) were compounded, aiming the development of composites with good mechanical properties, processability and electrical conductivity for use as pressure sensors. The electrical conductivity changes from 10(-11) to 10(-2) S.cm(-1) depending on the percentage of CB in the composite. It was also observed that the conductivity varies reversibly and linearly with the applied pressure. The latter demonstrates that this material can be used as pressure sensors.