Association between race/color and incidence of hypertension in the ELSA-Brasil population: investigating the mediation of racial discrimination and socioeconomic position

OBJECTIVE

To investigate the mediation effect of socioeconomic position and racial discrimination in the association between race/color and incidence of hypertension in 4-years follow up.

METHODS

We included 8,370 participants of the Longitudinal Study of Adult Health (ELSA-Brasil). A latent variable was constructed to represent socioeconomic position (SEP). The perception of discrimination was measured through an adaptation of the Lifetime Major Events Scale; and hypertension was defined using standard criteria. We investigated Body Mass Index (BMI) due to its role in proximal risk for hypertension. To investigate the mediating role of SEP and racial discrimination, we used structural equation modeling.

RESULTS

SEP had a direct and negative effect on HT incidence (HT incidence increased in worse SEP categories), while the effect of BMI on HT was direct and positive. We did not find significant direct effects of race/color and racial discrimination on HT. As for indirect effects, we observed associations between race/color and HT only through SEP mediation.

CONCLUSION

According to our results, race/color is indirectly related to HT incidence, mediated by SEP. Racial discrimination was not a mediator in the relationship between race/color and HT in the follow-up period.

Fabrication and characterization of polyimide-based 'smooth' titanium nitride microelectrode arrays for neural stimulation and recording

OBJECTIVE

As electrodes are required to interact with sub-millimeter neural structures, innovative microfabrication processes are required to enable fabrication of microdevices involved in such stimulation and/or recording. This requires the development of highly integrated and miniaturized systems, comprising die-integration-compatible technology and flexible microelectrodes. To elicit selective stimulation and recordings of sub-neural structures, such microfabrication process flow can beneficiate from the integration of titanium nitride (TiN) microelectrodes onto a polyimide substrate. Finally, assembling onto cuffs is required, as well as electrode characterization.

APPROACH

Flexible TiN microelectrode array integration and miniaturization was achieved through microfabrication technology based on microelectromechanical systems (MEMS) and complementary metal-oxide semiconductor processing techniques and materials. They are highly reproducible processes, granting extreme control over the feature size and shape, as well as enabling the integration of on-chip electronics. This design is intended to enhance the integration of future electronic modules, with high gains on device miniaturization.

MAIN RESULTS

(a) Fabrication of two electrode designs, (1) 2 mm long array with 14 TiN square-shaped microelectrodes (80  ×  80 µm²), and (2) an electrode array with 2 mm  ×  80 µm contacts. The average impedances at 1 kHz were 59 and 5.5 kΩ, respectively, for the smaller and larger contacts. Both designs were patterned on a flexible substrate and directly interconnected with a silicon chip. (b) Integration of flexible microelectrode array onto a cuff electrode designed for acute stimulation of the sub-millimeter nerves. (c) The TiN electrodes exhibited capacitive charge transfer, a water window of  -0.6 V to 0.8 V, and a maximum charge injection capacity of 154  ±  16 µC cm^-2.

SIGNIFICANCE

We present the concept, fabrication and characterization of composite and flexible cuff electrodes, compatible with post-processing and MEMS packaging technologies, which allow for compact integration with control, readout and RF electronics. The fabricated TiN microelectrodes were electrochemically characterized and exhibited a comparable performance to other state-of-the-art electrodes for neural stimulation and recording. Therefore, the presented TiN-on-polyimide microelectrodes, released from silicon wafers, are a promising solution for neural interfaces targeted at sub-millimeter nerves, which may benefit from future upgrades with die-electronic modules.

Performance assessment of an RFID system for automatic surgical sponge detection in a surgery room

A retained surgical instrument is a frequent incident in medical surgery rooms all around the world, despite being considered an avoidable mistake. Hence, an automatic detection solution of the retained surgical instrument is desirable. In this paper, the use of millimeter waves at the 60 GHz band for surgical material RFID purposes is evaluated. An experimental procedure to assess the suitability of this frequency range for short distance communications with multiple obstacles was performed. Furthermore, an antenna suitable to be incorporated in surgical materials, such as sponges, is presented. The antenna's operation characteristics are evaluated as to determine if it is adequate for the studied application over the given frequency range, and under different operating conditions, such as varying sponge water content.

Nafion-stabilised bimetallic Pt-Cr nanoparticles as electrocatalysts for proton exchange membrane fuel cells (PEMFCs)

The current study investigated the unique combination of alloying (Pt with Cr) and Nafion stabilisation to reap the benefits of catalyst systems with enhanced catalytic activity and improved durability in PEMFCs.

The current study investigated the unique combination of alloying (Pt with Cr) and Nafion stabilisation to reap the benefits of catalyst systems with enhanced catalytic activity and improved durability in PEMFCs. Pt–Cr alloy nanoparticles stabilised with Nafion were chosen in the current study owing to their higher stability in acidic and oxidising media at high temperatures compared to other Pt-transition metal alloys (e.g. Pt–Ni, Pt–Co). Two different precursor : reducing agent (1 : 10 and 1 : 20) ratios were used in order to prepare two different alloys, denoted as Pt–Cr 10 and Pt–Cr 20. The Pt–Cr 20 alloy system (with composition Pt₈₀Cr₂₀) demonstrated higher electrocatalytic activity for the oxygen reduction reaction compared to commercial Pt/C (TKK) catalysts. Accelerated stress tests and single cell tests revealed that Nafion stabilised alloy catalyst systems displayed significantly enhanced durability (only ∼20% loss of ECSA) compared with Pt/C (50% loss of ECSA) due to improved catalyst–ionomer interaction. Furthermore, the Pt–Cr 20 alloy system demonstrated a current density comparable to that of Pt/C making them promising potential electrocatalysts for proton exchange membrane fuel cells.

Phytotoxicity as an indicator of stability of broiler production residues

Beddings used for successive broiler lots act as substrate to absorb water and feed from the excreta and may be subsequently used as agricultural fertilizers. This study evaluated the physicochemical characteristics and the phytotoxicity of beddings used to raise five consecutive broiler lots in five aviaries. Samples were collected for beddings not used yet and for beddings used at each of the five broiler lots. Lettuce and cucumber seeds were considered as phytotoxicity bioindicators. As beddings were used for greater number of lots, N, Ca, K, Mg and P contents generally increased, but the C content decreased, the pH alkalinized and humidity was reduced (P < 0.05). The germination index for lettuce and cucumber seeds was reduced with increased bedding (P < 0.05). Beddings used for at least five broiler lots presented decreased C:N ratio and would not recommended for agricultural use due to its toxicity for both tested seeds.

A middleware for intelligent environments in ambient assisted living

The increasing elderly population is changing the demography of many countries, becoming a major issue for society. As a direct consequence of this demographic phenomenon, allied to technological developments and pressure to reduce healthcare costs, new healthcare technologies for proactive health and elder care is needed. However, interoperability issues among different levels of available technologies restricts a wider deployment among intermediate and end-users. This work presents a service-oriented middleware that was developed to provide access to the functionality offered by virtually any existing device, or application, in a residential setting, in a transparent and intuitive form. The proposed middleware abstracts the communication technologies involved, allowing to seemingly integrate different communication protocols, making possible the distributed cooperation of devices that were built as stand-alone products. As a test case, an application was built with the middleware to monitor blood pressure and electromyography signal using typical health devices.

Pt Diffusion Dynamics for the Formation Cr-Pt Core-Shell Nanoparticles

Layered core-shell bimetallic Cr-Pt nanoparticles were prepared by the formation and later reduction of an intermediate Pt-ion-containing supramolecular complex onto preformed Cr nanoparticles. The resultant nanoparticles were characterized by X-ray diffraction analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, and aberration-corrected scanning transmission electron microscopy. The results are consistent with the presence of Pt diffusion during or after bimetallic nanoparticle formation, which has resulted in a Pt/Cr-alloyed core and shell. We postulate that such Pt diffusion occurs by an electric-field-assisted process according to Cabrera-Mott theory and that it originates from the low work function of the preformed oxygen-defective Cr nanoparticles and the rather large electron affinity of Pt.

Extending Lifetime of Biomedical Wireless Sensor Networks using Energy-Aware Routing and Relay Nodes

Biomedical wireless sensor networks are a key technology to enable the development of new healthcare services and/or applications, reducing costs and improving the citizen's quality of life. However, since they deal with health data, such networks should implement mechanisms to enforce high levels of quality of service. In most cases, the sensor nodes that form such networks are small and battery powered, and these extra quality of service mechanisms mean significant lifetime reduction due to the extra energy consumption. The network lifetime is thus a relevant feature to ensure the necessary quality of service requirements. In order to maximise the network lifetime, and its ability to offer the required quality of service, new strategies are needed to increase the energy efficiency, and balance in the network. The focus of this work goes to the effective use of the available energy in each node, combined with information about the reliability of the wireless links, as a metric to form reliable and energy-aware routes throughout the network. This paper present and discusses two different deployment strategies using energy-aware routing and relay nodes, assessed for different logical topologies. The authors' conclusion is that the use of energy-aware routing combined with strategic placed relay nodes my increase the network lifetime as high as 45%.

Tailoring 3D single-walled carbon nanotubes anchored to indium tin oxide for natural cellular uptake and intracellular sensing

The ability to monitor intracellular events in real time is paramount to advancing fundamental biological and clinical science. We present the first demonstration of a direct interface of vertically aligned single-walled carbon nanotubes (VASWCNTs) with eukaryotic cells, RAW 264.7 mouse macrophage cell line. The cells were cultured on indium tin oxide with VASWCNTs. VASWCNTs entered the cells naturally without application of any external force and were shown to sense the intracellular presence of a redox active moiety, methylene blue. The technology developed provides an alluring platform to enable electrochemical study of an intracellular environment.

Low power wireless acquisition module for wearable health monitoring systems

This paper presents a low power wireless acquisition module for use within wearable health monitoring systems and Ambient Assisted Living applications. The acquisition module provides continuous monitoring of the user's electrocardiogram (ECG) and activity, as well as the local temperature at the module. The module is placed on the chest of the user, and its wearability is achieved due to its fabrication based on a flexible PCB, and by the complete absence of connecting wires, as a result of the integration of flexible and dry ECG monitoring electrodes on the acquisition module, which do not require preparation with electrolyte gel. The design of the acquisition module also aimed for the minimization of power consumption to enable long-term continuous monitoring, namely concerning the wireless link, for which a proprietary low power solution was adopted. A low power analog frontend was custom designed for single-lead ECG monitoring, achieving a current consumption of 220 εA. The wireless acquisition module has a current consumption down to 1.3 mA while processing the acquisition of sensor data, and 4 mA when the wireless transceiver is active.

Design and realization of a wireless sensor gateway for health monitoring

This paper describes the design and realization of a wireless sensor gateway (WSG) within a wireless sensor network (WSN) for health monitoring. The WSN allows recording and wireless transmission of biosignals, namely the electrocardiogram, pulse wave and body weight, which are important parameters for cardiovascular monitoring. These can be displayed, analysed, and saved on the WSG through a user interface based on a touch screen. The proposed WSG has the distinctive feature of using two different radio transceivers, exploiting the advantages of each device. Currently, most personal computers and handhelds have standardized Bluetooth interfaces (IEEE 802.15.1) but not ZigBee interfaces (IEEE 802.15.4). Hence, the proposed gateway is designed to receive data from wireless sensors through its ZigBee interface and to forward them to a personal computer via its Bluetooth interface. This feature, combined with simple touch screen menu navigation will reach increased patient compliance and consequently increased benefit for patient in terms of healthcare and safety.

Feature selection on movement imagery discrimination and attention detection

Noninvasive brain-computer interfaces (BCI) translate subject's electroencephalogram (EEG) features into device commands. Large feature sets should be down-selected for efficient feature translation. This work proposes two different feature down-selection algorithms for BCI: (a) a sequential forward selection; and (b) an across-group variance. Power rar ratios (PRs) were extracted from the EEG data for movement imagery discrimination. Event-related potentials (ERPs) were employed in the discrimination of cue-evoked responses. While center-out arrows, commonly used in calibration sessions, cued the subjects in the first experiment (for both PR and ERP analyses), less stimulating arrows that were centered in the visual field were employed in the second experiment (for ERP analysis). The proposed algorithms outperformed other three popular feature selection algorithms in movement imagery discrimination. In the first experiment, both algorithms achieved classification errors as low as 12.5% reducing the feature set dimensionality by more than 90%. The classification accuracy of ERPs dropped in the second experiment since centered cues reduced the amplitude of cue-evoked ERPs. The two proposed algorithms effectively reduced feature dimensionality while increasing movement imagery discrimination and detected cue-evoked ERPs that reflect subject attention.

Flexible PDMS -based dry electrodes for electro-optic acquisition of ECG signals in wearable devices

We present a new type of flexible dry copper electrodes based on Polydimethylsiloxane (PDMS) coatings, requiring no electrical contact with the body. Tests were performed in order to evaluate the performance of these types of electrodes using electro-optic techniques, suitable for wearable devices. Conductive and insulated PDMS layers were fabricated through a spin coating process, reaching a thickness of 100µ. These layers were then deposited on top of a flexible copper sheet. In a first set of experiments PDMS-based electrodes were compared with Ag/AgCl pre-gelled electrodes, showing comparable performances and lower noise signals. In order to test the influence of electrode area into signal strength, different sizes were chosen: 10.14 cm(2), 17.55 cm(2), 25.3 cm(2) and 39 cm(2). The results have shown that the signal strength increases with electrode area. We have also tested the influence of PDMS conductivity in signal strength, by adding two types of nickel to the pre-polymer solution. PDMS conductive electrodes have shown slightly better performances, with amplitudes higher than 200mV, which is the maximum value recorded with PDMS insulated electrodes.

3D electrode localization on wireless sensor networks for wearable BCI

This paper presents a solution for electrode localization on wearable BCI radio-enabled electrodes. Electrode positioning is a common issue in any electrical physiological recording. Although wireless node localization is a very active research topic, a precise method with few centimeters of range and a resolution in the order of millimeters is still to be found, since far-field measurements are very prone to error. The calculation of 3D coordinates for each electrode is based on anchorless range-based localization algorithms such as Multidimensional Scaling and Self-Positioning Algorithm. The implemented solution relies on the association of a small antenna to measure the magnetic field and a microcontroller to each electrode, which will be part of the wireless sensor network module. The implemented solution is suitable for EEG applications, namely the wearable BCI, with expected range of 20 cm and resolution of 5 mm.

Quality of service support in wireless sensor networks for emergency healthcare services

The reliable and efficient operation of emergency healthcare (e-emergency) services poses quality demands to the systems and underlying communication infrastructures. In this context, most existing wireless body sensor networks fall short in meeting these demands as they only offer an unreliable service delivery. e-Emergency systems must provide quality of service (QoS) support so that a pervasive and trustable assistance is provided to patients under health risk. This paper discusses the need for QoS in wireless e-health and e-emergency services. To demonstrate this need, some current and relevant e-health projects with QoS requirements are presented. The study reveals the importance of providing QoS support in this emerging field of application and provides a summary characterizing the e-health proposals herein presented.

Electrostatically stabilised nanoparticles: self-organization and electron-beam patterning

The self-organisation of citrate- and magnesium oleate-stabilised gold nanoparticles on SiO2/Si substrates was investigated. In drop deposition, nucleation of citrate-stabilised gold nanoparticles was observed at the rim of the droplet, symmetric or multibranched dendroid gold structures were found in the area between the rim and the central part of the droplet, depending on the drying temperature. Homogeneous submonolayer nanoparticle coverage was obtained by immersion of amineterminated SiO2/Si surfaces into a citrate-stabilised colloidal gold acidic solution. Drop deposition of magnesium oleate-stabilised gold nanoparticles onto the SiO2/Si surfaces resulted in the formation of uniformly close-packed nanoparticle arrays. Under electron beam irradiation, no apparent changes were found for monolayer films of citrate-stabilized particles, but sintering of the nanoparticles was observed in multilayer films. In contrast, coalescence of magnesium oleate-stabilised gold nanoparticle occurred in monolayer films after electron irradiation.