Redox switching of heteropolyanions entrapped in polypyrrole films investigated by ac electrogravimetry.

In this work, the global kinetics and the exchange of protons and free solvent at the film/electrolyte interface were investigated when a PPy film doped with HPA (heteropolyanions) is polarized. The ionic and electronic transfers for the PPy-HPA system are fast because the determined values of the resistances are relatively low (a few ohms). Depending on the applied potential, the global kinetics is controlled by both the ionic and electronic transfers. The transport effects were neglected here because the prepared films were very thin. Protons play an important role in charge compensation whatever the imposed potential on the PPy-HPA film. This phenomenon results from the acidic-basic properties of the SiMo(12)O(40)(4-) reduced species. A small quantity of water was also shown to be involved in the film reaction process.

Padrones de inervación y localización biométrica de los puntos motores del músculo bíceps braquial en el hombre / Innervation patterns and biometric localization of the motor points of the brachial biceps muscle in man

La inervación del músculo bíceps braquial se torna importante debido a su constitución y a la acción que ejerce a nivel del codo, sobretodo cuando existen lesiones en nervios espinales o médula espinal alta. Con el objetivo de conocer con detalles la disposición de sus nervios y localizar desde el punto de vista biométrico sus puntos motores, se estudiaron 46 miembros superiores de 23 cadáveres formolizados de individuos brasileños, adultos, en los cuales se consideró el número de ramos, longitud, nivel de origen y puntos de penetración en el vientre muscular respecto a una línea trazada entre los epicóndilos humerales (LBE). El nervio musculocutáneo envía un ramo para el músculo en estudio como un ramo común que luego se dividió para sus dos cabezas en 19 casos (41,3%); ramos independientes para cada cabeza se encontraron en las muestras restantes (58,7%). Con respecto al número de ramos, la cabeza larga recibió un ramo (R1) en 35 casos (76,1%), dos ramos (R1 y R2) en 9 casos (19,6%) y tres (R1,R2 y R3) en 2 casos (4,3%); para la cabeza corta se observó un ramo en 39 casos (84,7%), dos en 5 casos (10,9%) y tres en 2 casos (4,3%). Cada uno de los ramos dirigidos a las cabezas del músculo bíceps se dividió en ramos secundarios (RS). Para la cabeza corta, el ramo principal se dividió en 2 RS en 20 casos; en 3 RS en13 casos; en 4 RS en 4 casos, siendo directo sin dividirse en 2 casos. Para la cabeza larga el ramo principal se dividió en 2 RS en 16 casos; en 3 RS en 13; en 4 RS en 3; en 5 RS en un caso y en 6 RS en 1 caso y en una muestra, el ramo principal penetró en el vientre muscular sin dividirse. Los RS penetraron a niveles variables en el vientre muscular. Los resultados obtenidos pueden servir de referencia para procedimientos de punción en los puntos motores o en estudios electromiográficos.

The biceps brachii muscle innervation is important due to its constitution and its function in the elbow joint, mainly when there are in spinal nerves damages or high spinal cord. The purpose of this study was determine with details the nerves disposition of this muscle and locate its motor points. The upper limbs of 23 formolized cadavers of adult Brazilian individuals were studied, in whose it recorded the number of branches, length, origin levels and motor point localization. The localization were recorded using as reference point a line between the humerus epicondyles. The musculocutaneous nerve send a branch for a studied muscle as a common trunk that divides in two branches, each to a different head of the biceps in 19 cases (41.3%); independent branches for each head were observed in the other cases (58.7%). The long head received one branch in 35 cases (76.1%); two branches (B1, B2) in 9 cases (19.6%) and three branches (B1, B2, B3) in 2 cases (4.3%). Each branch divided in secondary branches (SB). In the short head the principal branch divided in two SB in 20 cases; in three SB in 13 cases; in fourth SB in 4 cases and not dividing in 2 cases. In the long head, the principal branch divided in two SB in 16 cases; in three SB in 13 cases; in fourth SB in 3 cases; in five SB in one case and in sixth SB in one case and not dividing in one case. The SB pierce in the muscular belly to different levels. These results can be to use as reference for the puncture procedures in the motor points or in electromyography studies.

Improved frequency/voltage converters for fast quartz crystal microbalance applications.

The monitoring of frequency changes in fast quartz crystal microbalance (QCM) applications is a real challenge in today's instrumentation. In these applications, such as ac electrogravimetry, small frequency shifts, in the order of tens of hertz, around the resonance of the sensor can occur up to a frequency modulation of 1 kHz. These frequency changes have to be monitored very accurately both in magnitude and phase. Phase-locked loop techniques can be used for obtaining a high performance frequency/voltage converter which can provide reliable measurements. Sensitivity higher than 10 mVHz, for a frequency shift resolution of 0.1 Hz, with very low distortion in tracking both the magnitude and phase of the frequency variations around the resonance frequency of the sensor are required specifications. Moreover, the resonance frequency can vary in a broad frequency range from 5 to 10 MHz in typical QCM sensors, which introduces an additional difficulty. A new frequency-voltage conversion system based on a double tuning analog-digital phase-locked loop is proposed. The reported electronic characterization and experimental results obtained with conducting polymers prove its reliability for ac-electrogravimetry measurements and, in general, for fast QCM applications.

New frequency/voltage converters for ac-electrogravimetric measurements based on fast quartz crystal microbalance.

A better understanding of the mechanisms located at the solid/electrolyte interface is becoming essential to the development of new applications in the electrochemical fields. The fast quartz crystal microbalance is an attractive and powerful gravimetric sensor which can be used in the dynamic regime to determine a mass/potential transfer function. The principle is equivalent to classical electrochemical impedance measurements; the only difference is the determination of mass changes given by the quartz crystal microbalance rather than current changes following sine wave modulations of the applied potential. This function appears very well adapted to characterize ionic exchanges at the electrochemical interface. Frequency/voltage converters are the key devices in translating the microbalance frequency response in terms of a continuous voltage change. The latter allows the transfer function to be obtained via a frequency response analyzer. Different converters were tested in this work in order to improve the performances of the experimental setup.

Electrochemical impedance spectroscopy investigations of a microelectrode behavior in a thin-layer cell: Experimental and theoretical studies.

Electrochemical impedance spectroscopy experiments were performed on a microdisk electrode in a thin-layer cell using a scanning electrochemical microscope for controlling the cell geometry. Experimental data showed that when the thin-layer thickness diminished, an additional low-frequency response appeared. It was ascribed to the radial diffusion of the electroactive species and was strongly dependent on the thin-layer dimensions (both thickness and diameter). Moreover, the numerical simulation of the impedance diagrams by finite element method calculations confirmed this behavior. An equivalent circuit based on a Randles-type circuit was proposed. Thus, the diffusion was described by introducing two electrical elements: one for the spherical diffusion and the other for the radial contribution. A nonlinear Simplex algorithm was used, and this circuit was shown to fit the impedance diagrams with a good accuracy.

Kinetic aspects of ion exchange in KhFek[Fe(CN)6]l*mH2O compounds: a combined electrical and mass transfer functions approach.

The present paper quantifies and develops the kinetic aspects involved in the mechanism of interplay between electron and ions presented elsewhere(1) for K(h)Fe(k)[Fe(CN)(6)](l)*mH(2)O (Prussian Blue) host materials. Accordingly, there are three different electrochemical processes involved in the PB host materials: H(3)O(+), K(+), and H(+) insertion/extraction mechanisms which here were fully kinetically studied by means of the use of combined electronic and mass transfer functions as a tool to separate all the processes. The use of combined electronic and mass transfer functions was very important to validate and confirm the proposed mechanism. This mechanism allows the electrochemical and chemical processes involved in the K(h)Fe(k)[Fe(CN)(6)](l)*mH(2)O host and Prussian Blue derivatives to be understood. In addition, a formalism was also developed to consider superficial oxygen reduction. From the analysis of the kinetic processes involved in the model, it was possible to demonstrate that the processes associated with K(+) and H(+) exchanges are reversible whereas the H(3)O(+) insertion process was shown not to present a reversible pattern. This irreversible pattern is very peculiar and was shown to be related to the catalytic proton reduction reaction. Furthermore, from the model, it was possible to calculate the number density of available sites for each intercalation/deintercalation processes and infer that they are very similar for K(+) and H(+). Hence, the high prominence of the K(+) exchange observed in the voltammetric responses has a kinetic origin and is not related to the amount of sites available for intercalation/deintercalation of the ions.

Thermodynamic aspects of ion intercalation in KhFek[Fe(CN)6]l*mH2O compounds: application to the Everit's Salt/Prussian blue transition.

The K(+) reversible processes for ion exchange in K(h)Fe(k)[Fe(CN)(6)](l)*mH(2)O host compounds (Prussian Blue) were thermodynamically analyzed. A thermodynamic approach was established and developed based on the consideration of a lattice-gas model where the electronic contribution to the chemical potential is neglected and the ion-host interaction is not considered. The occupation fraction of the intercalation process was calculated from the kinetic parameters obtained through ac-electrogravimetry in a previous paper. In this way, the mass potential transfer function introduces a new way to evaluate the thermodynamic aspect of intercalation. Finally, based on the thermodynamic approach, the energy used to put each K(+) ion into the host material was calculated. The values were shown to be in good agreement with the values obtained through transient techniques, for example, cyclic voltammetry. As a result, this agreement between theory and experimental data validates the thermodynamic approach considered here, and for the first time, the thermodynamic aspects of insertion were considered for mixed valence materials.

Mechanism for interplay between electron and ionic fluxes in KhFek[Fe(CN)6]l.mH2O compounds.

This paper develops a framework for the interpretation of ionic insertion/deinsertion reactions in an aqueous environment taking place in transition-metal hexacyanoferrates of the general formula K(h)[Fe(2+) (CN)(6)](l).mH(2)O, also called Prussian Blue. Three different processes were fully separated in the electrochemistry of these films. It was clearly identified that one of these electrochemical processes involves the insertion/deinsertion of H(3)O(+) (hydrated protons) through the channels of the K(h)[Fe(2+) (CN)(6)](l).mH(2)O structure to reach the film electroneutrality during the electron transfer between Everitt's Salt and Prussian Blue. The other electrochemical processes involve K(+) or H(+) (proton) exchange through the water crystalline structure existing in the channels of the K(h)[Fe(2+)(CN)(6)](l).mH(2)O structure.

Influence of the supersaturation on the nucleation-growth process of scale electrodeposition by in situ observation through a transparent quartz crystal microbalance.

An original technique allowed three in situ measurements to be obtained simultaneously, i.e. electrochemical and mass measurements and a microscope image of the interface between electrode and solution. The nucleation-growth process of CaCO3 deposition was investigated by varying different parameters which influenced the supersaturation coefficient, the Ca2+ concentration, pH and convection of the carbonically pure water near the substrate. The results showed that the variation of the scaling rate was due, for the two first cases, to an influence of the nucleation process whereas for the last case, the kinetics of scale deposition were modified by a shift of the growth rate.

Aspectos biométricos de los ramos motores del nervio musculocutáneo para el músculo braquial / Biometric aspects of the motor branches of the musculocutaneous nerve to the brachial muscle

Los puntos motores son el lugar de penetración de las fibras motoras en el músculo a través del epimisio por lo que su conocimiento es de importancia, sobretodo cuando se quiere electroestimular un músculo atrofiado. En relación a este tema, estudiamos la inervación del músculo braquial, describiendo con detalles los ramos que proceden del nervio musculocutáneo, considerando el nivel en que se originan, su distribución terminal y nivel de penetración en el tejido muscular. Para ello, estudiamos 46 miembros superiores de 23 cadáveres formolizados de individuos adultos, brasileños, de ambos sexos. Para determinar el punto de origen y el punto de penetración de los ramos musculares mencionados se consideró como referencia a la línea biepicondilar (LBE). El músculo braquial recibió ramos procedentes del nervio musculocutáneo en todos los casos (100 por ciento); un ramo fue encontrado en 15 casos (65,2 por ciento) en el lado derecho y en 18 casos (78,3 por ciento) en el izquierdo; con dos ramos se observaron 6 casos (26,1 por ciento) en el lado derecho y 2 casos (8,7 por ciento) en el izquierdo. También se presentaron 3 y 4 ramos. Cuando se presentó 1 ramo, su nivel de origen en el lado derecho fue en promedio de 130,1 ± 13,3 mm respecto de LBE y de 127,8 ± 12,0 mm en el izquierdo. Cuando se presentaron dos ramos, el nivel de origen de éstos, en el lado derecho fue en promedio de 126,2 ± 14,5 mm para el proximal y de100,2 ± 37,1 mm para el distal, siempre respecto de LBE. En el lado izquierdo, por tratarse de solo dos casos, no se calculó el promedio. Con respecto al punto de ingreso en el vientre muscular, la mayor parte de ellos lo hicieron por la parte medial del músculo, encontrando que cuando fue ramo único, 13 de ellos tuvieron esta característica en el lado derecho y 15 en el izquierdo. La casi totalidad de estos nervios se subdividieron en ramos menores (secundarios), encontrando 2, 3, 4 y 5 de ellos, los que penetraron en el tejido muscular a distintos niveles. Estos datos pueden servir de referencia a las cirugías de reinervación, bloqueo selectivo de puntos motores y tratamientos fisioterapéuticos en el brazo.

The deep plantar arch in humans: constitution and topography.

The integrity of the various structures within the feet depends on their blood supply. Lesions of the feet often require revascularization, which if successful avoids the need for amputation. To provide greater anatomical detail to aid vascular surgery and imaging, the anatomy and constitution of the deep plantar arch was studied in 50 adult cadaveric feet. The arteries of the foot were injected with red neoprene latex and dissected under magnification. The deep plantar arch, present in all feet, was the result of anastomosis between the deep plantar artery and the deep branch of the lateral plantar artery. The deep plantar artery was predominant in 72% of specimens (Type I arches) and the lateral plantar artery in 22% (Type II), with the contribution being equal in 6% (Type III). The medial plantar artery contributed to the medial segment of the deep plantar arch by its deep branch in 12% of specimens. The distance between the deep plantar arch and each interdigital commissure was generally constant, averaging 29% of total foot length. The deep plantar arch was located in the middle third of the foot in all specimens, being in the distal part of this third in 90%. The deep plantar arch is, therefore formed mainly by the deep plantar artery, a branch of the dorsal artery of foot; its location can be estimated if foot length is known.

Magnetic water treatment for scale prevention.

A home-made magnetic device was built with permanent magnets for treating scaling waters. Its efficiency was evaluated by measuring the remaining ionic calcium at the output of the device by means of an ion selective electrode. The scaling power of the treated water was estimated through an electrochemical scaling test. Chroamperometric curves and chronoelectrogravimetric curves were plotted to obtain the scaling time and the nucleation time of the scale deposition. The variation of the efficiency of the magnetic treatment was studied when the length of treatment, the flow velocity of the scaling water in the device, the material of the pipe where the scaling water flowed were changed. An empirical relationship, which gives the value of the efficiency in function of the length of treatment and the flow velocity, was proposed. Possible mechanisms of action of the magnetic treatment were discussed.

Immunodetection by quartz crystal microbalance. A new approach for direct detection of rabbit IgG and peroxidase.

Biodetection is one of the most important challenges for the twenty-first century: many fields are concerned, mainly environmental and medical. The quartz crystal microbalance (QCM) may offer great possibilities for this purpose: a direct response signal, which characterizes the binding event between a sensitive layer, immobilized onto the surface transducer, and the analyte to be detected, can be obtained. However, for the detection of small biomolecules such as antigens, it is quite difficult to obtain an observable signal that corresponds directly to the binding event. In general, this is owing to the lack of mass sensitivity of the commonly used QCM, with 5- to 10-MHz quartz crystals. For improving this mass sensitivity, a 27-MHz quartz resonator was developed and incorporated in a flow-through microcell. Two biospecies, IgG rabbit and peroxidase enzyme, were studied with this ultra-sensitive QCM in terms of specificity, detection limit, and calibration curve.

Huesos suturales en el pterion / Sutural bones in the pterion

Las variaciones de los huesos del cráneo son de interés para la anatomía, antropología física, imagenología y medicina legal. Con el propósito de aportar mayores detalles sobre los huesos suturales que se presentan en el pterion, fueron analizados 205 cráneos secos de individuos brasileños, adultos, de ambos sexos, blancos y no blancos. El hueso sutural fue observado en 31 cráneos (15,1 por ciento), localizándose 19 en el lado derecho (61,3 por ciento), 8 en el izquierdo (25,8 por ciento) y 4 en ambos lados (12,9 por ciento. Con relación al sexo, 14 estuvieron presentes en cráneos masculinos (45,2 por ciento) y 17 en femeninos (54,8 por ciento). En relación al grupo étnico, 20 eran del grupo blancos (64,5 por ciento) y 11 de no blancos (35,5 por ciento). Las articulaciones de este hueso sutural con los huesos vecinos fueron clasificados en 4 tipos: tipo I, donde se articuló con los huesos frontal, parietal, ala mayor del esfenoides y temporal, disposición encontrada en 17 cráneos (54,8 por ciento); tipo II, donde se articuló con el parietal, temporal y ala mayor del esfenoides, encontrado en 11 cráneos (35,5 por ciento); tipo III, donde se articuló con el temporal, frontal y ala mayor del esfenoides, observado en 2 cráneos (6,5 por ciento) y tipo IV, donde se articuló con el parietal, frontal y ala mayor del esfenoides, encontrado en 1 cráneo (3,2 por ciento). Correlacionando las variables lado, sexo, grupo étnico y hueso sutural, el análisis estadístico reveló que la presencia de estos huesos es significativa en los individuos blancos y en el lado derecho

Perforating branches: important contribution to the formation of the dorsal metacarpal arteries.

The perforating branches that originate from the deep palmar arch of the hand have been studied to provide a complete anatomical description of these vessels and assess their importance in the blood collateral pathway of the hand. We injected latex into the arteries of 50 cadaveric hands of 25 adults, of both sexes, all of Brazilian origin. These were dissected under a stereoscopic microscope. The perforating branch of the second interosseous space originated from the deep palmar arch in 80% of the cases, and it corresponded to the radial artery passing through the second space in 16%; the one of the third interosseous space originated from the deep palmar arch in 76% of the cases and from the palmar metacarpal artery of the third interosseous space in 16%; the one of the fourth interosseous space originated from the deep palmar arch in half the cases, from the deep palmar branch of the ulnar artery in 14%, and from the palmar metacarpal artery of this space in 18%. The perforating branch of the second space anastomosed with the second dorsal metacarpal artery (DMA) in 60% of the cases and formed it in 10%; the one of the third space anastomosed with the third DMA in 20% and formed it in 64%; the one of the fourth space anastomosed with the fourth DMA in 8% and formed it in 78%. These vessels are an important anastomotic pathway between the dorsal carpal network and the deep arteries of the hand and are important in the supply to the dorsum.

Validation of antibody-based recognition by piezoelectric transducers through electroacoustic admittance analysis.

The development of immunosensors based on piezoelectric transducers is widely investigated due to their attractive potentialities. The quartz crystal microbalance (QCM) may give a direct response signal which characterizes the binding event between a sensitive layer, immobilized onto the surface transducer, and the analysis to be detected. However, for small biomolecules, such as some antigens, it is quite difficult to obtain an observable signal. This is mainly due to the lack of sensitivity of the commonly used QCM (5 to 10 MHz quartz crystal). Moreover, the mass estimated with the QCM response through the Sauerbrey equation and the mass which can be measured thanks to other analytical techniques, in our case an enzymatic assay, are different: the deposited mass is generally overestimated by the QCM. To validate QCM mass measurements and, therefore antigens recognition, the interactions of acoustic shear waves with a biolayer were investigated during enzyme adsorption onto the microbalance gold electrode or during the antibody/antigen binding. Electroacoustic admittance was measured around the resonance frequency of a 27 MHz quartz resonator in parallel with microbalance measurements. The parameters which characterize the quartz microbalance equivalent circuit were compared with the classical microbalance frequency. The mass overestimation, given by the microbalance, could be explained either by modification of the rheological properties of the sensitive layers and/or by an inadequacy of the assay performed.

A biometric study on the relationships between the deep palmar arch and the superficial palmar arch, the distal wrist and palmar creases.

The topographical localisation of the palmar arches is important in hand surgery. The aim of this study was to contribute with biometric data on their positions and to correlate this with the size od the palm. We studied 60 hands of 30 adult fixed cadavers, of Brazilian origin, from both sexes and between the ages of 21 and 70 years. The arteries of 54 hands were injected with latex Neoprene. Before dissection the distance between distal wrist crease (DWC) and the proximal palmar digital crease of the middle finger (PDMC) was measured. Also, we recorded the distance between the DWC and the proximal and distal palmar creases (PPC, DPC). After dissecting the superficial palmar region, the distance between the superficial palmar arch (SPA) and the DWC was recorder. We then dissected the deep palmar arch (DPA). The average distance between the DPA and DWC was always measured in the midline of the palm. The average distance DWC-DPA was 33.7 +/- 2.6 mm in the female and 36 +/- 4.0 mm in the male. The difference was statistically significant. The average distance between DPA and the PPC was 24.2 +/- 3.0 mm in the female and 27.1 +/- 4.1 mm in the male; this difference was significant. In 83% of cases the DPA was proximal to the SPA and in 14.9% was distal to it. The linear regression test for the relation between DWC-PDMC and DWC-DPA was significant in the male and this fact allowed us to obtain the linear equation to predict the distance DWC-DPA. Other parameters were also considered. The results may be useful as a reference to radiologists as well as to surgeons.

Median artery and superficial palmar branch of the radial artery in the carpal tunnel.

In the carpal tunnel there are the flexor muscle tendons, their sheaths, and the median nerve. Because its walls are inflexible, any thickening of its components that reduce its area may compress the median nerve. There are many reasons for nerve compression, including persistence of the median artery into adult life. We dissected the arteries in the carpal tunnel of 102 hands of 51 adult cadavers of both sexes, age range 23-77 years, and injected latex into 42 hands. In the carpal tunnel we sought the median artery and the superficial palmar branch of the radial artery. We found the median artery in 23 of 102 cases (23%), and its calibre ranged from 0.7 to 2.7 mm, mean (SD) 1.6 (0.5) mm. In 16 cases it made up part of the superficial palmar arch. The superficial palmar branch of the radial artery was partly responsible for the distal irrigation of the hand in 48 cases (47%); and in three hands (3%) it passed through the carpal tunnel. The external diameters of these vessels were 1.8, 1.9, and 1.8 mm, respectively. These arteries might cause compression of the median nerve and consequently the carpal tunnel syndrome.

Abnormal extrapelvic course of the inferior gluteal artery.

At its extrapelvic course the inferior gluteal a. is found to be strictly related to the sciatic n. This relationship has been described in a general way, emphasizing its medial localization in respect to the nerve. Clinicosurgical reports describe cases of aneurysms of the inferior gluteal a. on its extrapelvic course and subsequent compression at the nerve. In order to get further details on the relationship between these two structures, 80 gluteal regions from 40 cadavers of adult Brazilian individuals, 29 males and 11 females, were dissected. The inferior gluteal a. was found medial to the sciatic n. in 62 cases (77.5%); in the 18 remaining (22.5%) the trunk of the artery or one of its branches perforated the nerve. Of these, 14 (77.8%) were males and 4 (22.2%) females. This disposition was found 8 times (44.4%) on the right and 10 (55.6%) on the left side; was unilateral in 4 individuals (1 on the right and 3 on the left side) and bilateral in 7. The course of the inferior gluteal a. through the sciatic n. and/or the presence of aneurysms of this artery should be considered as a possible cause of nerve compression.