Mn-doped cubic BN as an atomiclike memory device: A density functional study

We investigate the electronic properties of Mn(B) substitutional doping in cubic boron nitride (BN), for different charge states, using density functional theory (DFT) calculations. We show that the neutral Mn has a nonmagnetic ground state (S=0). Upon charge injection, it is unambiguously shown that the Mn(B)(-) has a high-spin configuration with a strong, localized magnetic moment of 5 mu(Bohr). We developed a simple model, parameterized by the DFT results, that allows us to interpret the rules played by the crystal-field and exchange-correlation splitting in the magnetization process.

Organic molecule assembled between carbon nanotubes: A highly efficient switch device

We report a highly efficient switch built from an organic molecule assembled between single-wall carbon nanotube electrodes. We theoretically show that changes in the distance between the electrodes alter the molecular conformation within the gap, affecting in a dramatic way the electronic and charge transport properties, with an on/off ratio larger than 300. This opens up the perspective of combining molecular electronics with carbon nanotubes, bringing great possibilities for the design of nanodevices.

A sampling device to quantify offspring release of sessile marine invertebrates

Quantifying the rate of propagule release is of most importance to estimate reproductive output of natural populations, but simple methods to obtain such data are seldom reported. We designed and tested an inexpensive apparatus capable of reliably measure the release of gametes, eggs or larvae of sessile marine invertebrates in vertical walls. A population of the acom barnacle Chthamalus bisinuatus was sampled with this trap over 68d to obtain a time series of naupliar release. An apparent semilunar trend is shown, indicating the effectiveness of this sampling method.

Evaluation of pain before and after vaginal delivery

Purpose: The objective of this Pilot Study was to determine pain characteristics of pregnant women immediately before and after childbirth by vaginal delivery and to compare them with the pain intensity reported by physicians. Methods: We evaluated 20 Brazilian women between September and December 2007 with the WHOQOL-Bref instrument, VAS, McGill Pain Questionnaire, and Anxiety Adapted Scale. We interviewed the obstetrician with the VAS about the patient`s pain, Data were analyzed with the chi-square test. Results: Mean age was 22.35 years (SD = 6.24, range 15-39 years). It was necessary to use oxytocin in 15 (75%) patients, which had no correlation with anxiety degree. Higher intensity of pain (p < 0.05) and higher anxiety index (p < 0.05) were more common in women in the first pregnancy. Conclusions: Higher pain intensity was associated with higher anxiety levels (p < 0.05). Around half of the obstetricians` VAS scores were lower than the VAS scores of women, and probably pain at labor was underestimated and not controlled. Higher indices of anxiety and pain were associated, and were more frequent in women in the first pregnancy.

Use of hyaluronidase to prevent perineal trauma during spontaneous delivery: A pilot study

Our objective was to compare the frequency, degree, and location of perineal trauma during spontaneous delivery with or without perineal injections of hyaluronidase (HAase). This was a randomized, controlled pilot study, conducted in a midwifie-led hospital birth center in Sao Paulo, Brazil. Primiparous women (N = 139) were randomly assigned to an intervention group (HAase injection, n = 71) or to a control group (no injection, n = 68). Significant differences were noted between the two groups in frequency of perineal trauma (intervention, 39.4%; control, 76.5%), degree of spontaneous laceration (intervention, 0.0%; control, 82.4%), and laceration located in the posterior region of the perineum (intervention, 54.2%; control, 84.3%). When episiotomy and second-degree lacerations were considered together and women with intact perineum were excluded from the analysis, the difference between the groups was no longer significant. With the use of the HAase enzyme, the relative risk was 0.5 for perineal trauma and 0.0 for second-degree lacerations. The present findings suggest that perineal injection of HAase prevented perineal trauma. These findings provide strong rationale for a larger follow-up study.

Effectiveness of local anaesthetics with and without vasoconstrictors for perineal repair during spontaneous delivery: Double-blind randomised controlled trial

Objective: to investigate the use of local anaesthetics, in the presence or absence of vasoconstrictors, for perineal repair during spontaneous delivery. Design: double-blind, randomised-controlled trial. Setting: a birth centre, in the city of Sao Paulo, Brazil. Participants: from June to December 2004, a total of 96 women were allocated into three groups (first-degree perineal lacerations, second-degree perineal lacerations or episiotomy), and treated with local anaesthesia (1% lidocaine or 1% lidocaine with epinephrine) (n = 16 per treatment per group). Interventions: an initial local infiltration of the anaesthetic solution was given so that episiotomy could be carried out (5 ml) and to suture spontaneous lacerations (1 ml), followed by repeated doses (1 ml) until pain was completely inhibited. Measurements and findings: the main outcome measurement was the volume of anaesthetic used during episiotomy and perineal suture. Our data suggest that the concomitant use of the vasoconstrictor resulted in a significantly lower average volume used in the treatment of first-degree (1 ml, 95% confidence interval (0) 0.4-1.6) and second-degree (3.7 ml, 95% CI 1.6-5.8) lacerations (p = 0.002 and 0.001, respectively). A 0.3 ml (95% CI 1.5-2.1) average decrease in anaesthetic volume was observed with episiotomy (p = 0.724). The maximum volume of anaesthetic used with and without vasoconstrictor was 1-2 ml in 95% and 3-4 ml in 50% of first-degree lacerations, respectively, and 1-6 ml in 88% and 7-15 ml in 81% of second-degree lacerations, respectively. For episiotomy, the maximum dose was 15 ml, regardless of anaesthetic solution used. Key conclusions: our data confirm the hypothesis that the use of anaesthetics in conjunction with vasoconstrictors is more effective than anaesthetics alone in the repair of perineal lacerations, but not for episiotomy. (C) 2007 Elsevier Ltd. All rights reserved.

SJL dystrophic mice express a significant amount of human muscle proteins following systemic delivery of human adipose-derived stromal cells without immunosuppression

Limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of disorders characterized by progressive degeneration of skeletal muscle caused by the absence of or defective muscular proteins. The murine model for limb-girdle muscular dystrophy 2B (LGMD2B), the SJL mice, carries a deletion in the dysferlin gene that causes a reduction in the protein levels to 15% of normal. The mice show muscle weakness that begins at 4-6 weeks and is nearly complete by 8 months of age. The possibility of restoring the defective muscle protein and improving muscular performance by cell therapy is a promising approach for the treatment of LGMDs or other forms of progressive muscular dystrophies. Here we have injected human adipose stromal cells (hASCs) into the SJL mice, without immunosuppression, aiming to assess their ability to engraft into recipient dystrophic muscle after systemic delivery; form chimeric human/mouse muscle fibers; express human muscle proteins in the dystrophic host and improve muscular performance. We show for the first time that hASCs are not rejected after systemic injection even without immunosuppression, are able to fuse with the host muscle, express a significant amount of human muscle proteins, and improve motor ability of injected animals. These results may have important applications for future therapy in patients with different forms of muscular dystrophies.

Developing and implementing an open and non-proprietary device description for FOUNDATION fieldbus based on software standards

Support for interoperability and interchangeability of software components which are part of a fieldbus automation system relies on the definition of open architectures, most of them involving proprietary technologies. Concurrently, standard, open and non-proprietary technologies, such as XML, SOAP, Web Services and the like, have greatly evolved and been diffused in the computing area. This article presents a FOUNDATION fieldbus (TM) device description technology named Open-EDD, based on XML and other related technologies (XLST, DOM using Xerces implementation, OO, XMIL Schema), proposing an open and nonproprietary alternative to the EDD (Electronic Device Description). This initial proposal includes defining Open-EDDML as the programming language of the technology in the FOUNDATION fieldbus (TM) protocol, implementing a compiler and a parser, and finally, integrating and testing the new technology using field devices and a commercial fieldbus configurator. This study attests that this new technology is feasible and can be applied to other configurators or HMI applications used in fieldbus automation systems. (c) 2008 Elsevier B.V. All rights reserved.

A biomimetic piezoelectric pump: Computational and experimental characterization

Flow pumps have been developed for classical applications in Engineering, and are important instruments in areas such as Biology and Medicine. Among applications for this kind of device we notice blood pump and chemical reagents dosage in Bioengineering. Furthermore, they have recently emerged as a viable thermal management solution for cooling applications in small-scale electronic devices. This work presents the performance study of a novel principle of a piezoelectric flow pump which is based oil the use of a bimorph piezoelectric actuator inserted in fluid (water). Piezoelectric actuators have some advantages over classical devices, such as lower noise generation and ease of miniaturization. The main objective is the characterization of this piezoelectric pump principle through computational simulations (using finite element software), and experimental tests through a manufactured prototype. Computational data, Such as flow rate and pressure curves, have also been compared with experimental results for validation purposes. (C) 2009 Elsevier B.V. All rights reserved.

Electro-optically sensitive diamond-like carbon thin films deposited by reactive magnetron sputtering for electronic device applications

The goal of this work is to study and relate electrical and optical properties of diamond-like carbon (DLC) thin films for applications in electronic devices. DLC films were deposited in a reactive RF magnetron sputtering system on p-type silicon and glass substrates. The target was a 99.9999% pure, 6 in. diameter graphite plate and methane was used as processing gas. Eight DLC films were produced for each substrate, varying deposition time, the reactor pressure between 5 mTorr and 10 mTorr while the RF power was applied at 13.56 MHz and varied between 100, 150, 200 and 250W. After deposition, the films were analyzed by I-V and C-V measurements (Cheng et al. (2004) [1]) in order to determine the electric resistivity, photo-current response and dielectric constant, optical transmittance, used to find the optical gap by the Tauc method; and by photoluminescence analysis to determine the photoemission and confirm the optical band gap. These characteristics are compared and the influence of the deposition parameters is discussed. (C) 2011 Published by Elsevier B.V.

Development and fabrication of an optimized thermo-electro-optic device using a Mach-Zehnder interferometer

The development and fabrication of a thermo-electro-optic sensor using a Mach-Zehnder interferometer and a resistive micro-heater placed in one of the device`s arms is presented. The Mach-Zehnder structure was fabricated on a single crystal silicon substrate using silicon oxynitride and amorphous hydrogenated silicon carbide films to form an anti-resonant reflective optical waveguide. The materials were deposited by Plasma enhanced chemical vapor deposition technique at low temperatures (similar to 320 degrees C). To optimize the heat transfer and increase the device response with current variation, part of the Mach-Zehnder sensor arm was suspended through front-side bulk micromachining of the silicon substrate in a KOH solution. With the temperature variation caused by the micro-heater, the refractive index of the core layer of the optical waveguide changes due to the thermo-optic effect. Since this variation occurs only in one of the Mach-Zehnder`s arm, a phase difference between the arms is produced, leading to electromagnetic interference. In this way, the current applied to the micro-resistor can control the device output optical power. Further, reactive ion etching technique was used in this work to define the device`s geometry, and a study of SF6 based etching rates on different composition of silicon oxynitride films is also presented. (C) 2007 Elsevier B.V. All rights reserved.

Single Axis Controlled Hybrid Magnetic Bearing for Left Ventricular Assist Device: Hybrid Core and Closed Magnetic Circuit

In previous studies, we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology (IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the active control is executed in only one degree of freedom, in the axial direction of the rotor. Remaining degrees of freedom, excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of Sao Paulo University, Brazil. This article shows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores that combine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magnetic circuit closed by an iron core. After preliminary analysis, a pump prototype has been developed for each solution and has been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution was evaluated by in vitro experiments and guidelines are extracted for future improvements. Tests have shown good results and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD.

Magnetic suspension of the rotor of a ventricular assist device of mixed flow type

This work presents results of preliminary studies concerning application of magnetic bearing in a ventricular assist device (VAD) being developed by Dante Pazzanese Institute of Cardiology-IDPC (Sao Paulo, Brazil). The VAD-IDPC has a novel architecture that distinguishes from other known VADs. In this, the rotor has a conical geometry with spiral impellers, showing characteristics that are intermediate between a centrifugal VAD and an axial VAD. The effectiveness of this new type of blood pumping principle was showed by tests and by using it in heart surgery for external blood circulation. However, the developed VAD uses a combination of ball bearings and mechanical seals, limiting the life for some 10 h, making impossible its long-term use or its use as an implantable VAD. As a part of development of an implantable VAD, this work aims at the replacement of ball bearings by a magnetic bearing. The most important magnetic bearing principles are studied and the magnetic bearing developed by Escola Politecnica of Sao Paulo University (EPUSP-MB) is elected because of its very simple architecture. Besides presenting the principle of the EPUSP-MB, this work presents one possible alternative for applying the EPUSP-MB in the IDPC-VAD.

A new approach to heart valve tissue engineering: mimicking the heart ventricle with a ventricular assist device in a novel bioreactor

The `biomimetic` approach to tissue engineering usually involves the use of a bioreactor mimicking physiological parameters whilst supplying nutrients to the developing tissue. Here we present a new heart valve bioreactor, having as its centrepiece a ventricular assist device (VAD), which exposes the cell-scaffold constructs to a wider array of mechanical forces. The pump of the VAD has two chambers: a blood and a pneumatic chamber, separated by an elastic membrane. Pulsatile air-pressure is generated by a piston-type actuator and delivered to the pneumatic chamber, ejecting the fluid in the blood chamber. Subsequently, applied vacuum to the pneumatic chamber causes the blood chamber to fill. A mechanical heart valve was placed in the VAD`s inflow position. The tissue engineered (TE) valve was placed in the outflow position. The VAD was coupled in series with a Windkessel compliance chamber, variable throttle and reservoir, connected by silicone tubings. The reservoir sat on an elevated platform, allowing adjustment of ventricular preload between 0 and 11 mmHg. To allow for sterile gaseous exchange between the circuit interior and exterior, a 0.2 mu m filter was placed at the reservoir. Pressure and flow were registered downstream of the TE valve. The circuit was filled with culture medium and fitted in a standard 5% CO(2) incubator set at 37 degrees C. Pressure and flow waveforms were similar to those obtained under physiological conditions for the pulmonary circulation. The `cardiomimetic` approach presented here represents a new perspective to conventional biomimetic approaches in TE, with potential advantages. Copyright (C) 2010 John Wiley & Sons, Ltd.

Particle-Image Velocimetry Study of a Pediatric Ventricular Assist Device

Particle-image velocimetry (PIV) was used to visualize the flow within an optically transparent pediatric ventricular assist device (PVAD) under development in our laboratory The device studied is a diaphragm type pulsatile pump with an ejection volume of 30 ml per beating cycle intended for temporary cardiac assistance as a bridge to transplantation or recovery in children. Of particular interest was the identification of flow patterns, including regions of stagnation and/or strong turbulence that often promote thrombus formation and hemolysis, which can degrade the usefulness of such devices. For this purpose, phase-locked PIV measurements were performed in planes parallel to the diaphram that drives the flow in the device. The test fluid was seeded with 10 Am polystyrene spheres, and the motion of these particles was used to determine the instantaneous flow velocity distribution in the illumination plane. These measurements revealed that flow velocities up to 1.0 m/s can occur within the PVAD. Phase-averaged velocity fields revealed the fixed vortices that drive the bulk flow within the device, though significant cycle-to-cycle variability was also quite apparent in the instantaneous velocity distributions, most notably during the filling phase. This cycle-to-cycle variability can generate strong turbulence that may contribute to greater hemolysis. Stagnation regions have also been observed between the input and output branches of the prototype, which can increase the likelihood of thrombus formation. [DOI: 10.1115/1.4001252]