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The drive to replace scarce and expensive Pt-based electrocatalysts for oxygen reduction reaction (ORR) has led to the development of a group of electrocatalysts composed of transition-metal ion centers coordinated with four nitrogen groups (M-N4). Among these, metal phthalocyanines (MPcs), due to low cost of preparation, highly conjugated structure as well as high thermal and chemical stability, have received a great interest. The catalytic activity of MPcs can be improved by employing conducting supports. Here, in this report, we have solvothermally synthesized graphene-supported zinc phthalocyanine nanostructures, and their ORR kinetics and mechanism have been investigated in neutral solution (pH = 7) by using the rotating disk electrode technique. The as-synthesized nanocomposite followed a 4e− reduction pathway. The onset potential (−0.04 V versus Ag/AgCl) found in this work can be comparable with other state-of-the-art material, demonstrating good performance in neutral solution. The fascinating performance leads the nanocomposite material toward future energy applications.
Crystal structure analysis of a pyrazole carboxylic acid derivative, 5-(trifluoromethyl)-1-phenyl-1H-pyrazole-4-carboxylic acid (1) has been carried out from laboratory powder X-ray diffraction data. The crystal packing in the pyrazole carboxylic acid derivative exhibits an interplay of strong O–H…O, C–H…N and C–H…F hydrogen bonds to generate a three-dimensional molecular packing via the formation of R22(8) and R22(9) rings. Molecular electrostatic potential calculations indicated that carbonyl oxygen, pyrazole nitrogen and fluorine atoms to be the strongest acceptors. The relative contribution of different interactions to the Hirshfeld surface of pyrazole carboxylic acid and a few related structures retrieved from CSD indicates that H…H, N…H and O…H interactions can account for almost 70% of the Hirsfeld surface area in these compounds.
The anatomy of the membranous labyrinth within the vestibule has direct implications for surgical intervention. The anatomy of the otoliths has been studied, but there is limited information regarding their supporting connective tissue structures such as the membrana limitans in humans.
One guinea pig and 17 cadaveric human temporal bones were scanned using micro computed tomography, after staining with 2 per cent osmium tetroxide and preservation with Karnovsky's solution, with a resolution from 1 µm to 55 µm. The data were analysed using VGStudio Max software, rendered in three-dimensions and published in augmented reality.
In 50 per cent of ears, the membrana limitans attached directly to the postero-superior part of the stapes footplate. If attachments were present in one ear, they were present bilaterally in 100 per cent of cases.
Micro computed tomography imaging allowed three-dimensional assessment of the inner ear. Such assessments are important as they influence the surgical intervention and the evolution of future innovations.
The occurrence of pesticidal pollution in the environment and the resistance in the mosquito species makes an urge for the safer and an effective pesticide. Permethrin, a poorly water-soluble pyrethroid pesticide, was formulated into a hydrodispersible nanopowder through rapid solvent evaporation of pesticide-loaded oil in water microemulsion. Stability studies confirmed that the nanopermethrin dispersion was stable in paddy field water for 5 days with the mean particle sizes of 175.3 ± 0.75 nm and zeta potential of −30.6 ± 0.62 mV. The instability rate of the nanopermethrin particles was greater in alkaline (pH 10) medium when compared with the neutral (pH 7) and acidic (pH 4) dispersion medium. The colloidal dispersion at 45°C was found to be less stable compared with the dispersions at 25 and 5°C. The 12- and 24-h lethal indices (LC50) for nanopermethrin were found to be 0.057 and 0.014 mg l−1, respectively. These results were corroborative with the severity of damages observed in the mosquito larvae manifested in epithelial cells and the evacuation of the midgut contents. Further, the results were substantiated by the decrease in cellular biomolecules and biomarker enzyme activity in nanopermethrin treated larvae when compared to bulk and control treatment.
Crystal structures of two fused cyclic compounds, 4-(methyl(sulfonyl)methoxy-2-vinyl)-2S*,3aR*,4S*,5,7aS*-(hexahydro-1H-indan-3a-yl)methylmethanesulfonate (1) and (1S*,2S*,4S*,7R*)-7-(dimethyl(phenyl)silyl)-4′,5′-dihydro-2′H-spiro[bicyclo[2.2.1]heptene-2,3′-furan]-2′-one (2), have been solved from laboratory X-ray powder diffraction data using direct space approach and refined following the Rietveld method. In the absence of strong hydrogen bond donating groups, the crystal packing of 1 and 2 exhibits C–H ⋯ O hydrogen bonds and C–H ⋯ π interactions forming two-dimensional (2D) supramolecular network. The nature of intermolecular interactions in 1 and 2 has been analyzed through the Hirshfeld surface and 2D fingerprint plots. The density functional theory optimized molecular geometries in 1 and 2 agree closely with those obtained from the crystallographic study. Hirshfeld surface analysis of 1, 2 and a few related fused carbocyclic and carbooxacyclic systems retrieved from the Cambridge Structural Database indicates that about 85% of Hirshfeld surface area in these compounds are because of H ⋯ H and O ⋯ H interactions.
The physical mechanisms responsible for electrically-induced parametric degradation in GaN-based high electron mobility transistors are examined using a combination of experiments, device simulation, and first-principles defect analysis. A relatively simple formulation is developed under the assumption that the hot-electron scattering cross-section is independent of the electron energy. In this case, one can relate the change in defect concentration to the operational characteristics of a device, such as the spatial and energy distribution of electrons (electron temperature), electric field distribution, and electron energy loss to the lattice.
Diamond like carbon (DLC) and composite nickel incorporated diamond-like carbon (Ni-DLC) films have been synthesized on ITO coated glass substrates using low voltage electrodeposition method. Modifications of structural and optical properties of thin films have been investigated with varying Ni concentration. Average grain size of Ni-DLC granules is found to decrease with increasing molarity of Ni in electrolytic solution. XRD pattern depicts multi-phase nature of Ni-DLC film. Incorporation of Ni nanoparticles in DLC matrix has been confirmed by TEM. Interestingly optical bandgap energy decreases from 2.31 to 1.58 eV with decrease in nickel content in the electrolytic bath. Simultaneously Urbach energy exhibits an increasing trend from 1.972 to 2.374 eV. Presence of sp2 and sp3 bonded carbons has been indicated by FTIR spectra. The number of sp2 bonding in carbon matrix is enhanced with dilution of electrolyte. The peaks in the range of ~600–750 cm−1 in Ni-DLC films have been attributed to metal incorporation into DLC matrix. Study reveals that the bandgap and the particle size of carbon nanocomposite films can be tailored by controlling the amount of nickel in the electrolyte.
Crystal structures of N-(2-chlorophenyl) acetamide (1) and phenyl (2-bromomethyl) benzoate (2) have been determined from laboratory X-ray powder diffraction data. In addition to intermolecular N–H···O and C–H···O hydrogen bonds, the crystal packing in (1) and (2) exhibits weak C–H···Cl/Br interactions, which facilitate formation of three-dimensional architectures. Hirshfeld surface analysis of compounds (1), (2), and a few related chloro- and bromo-phenyl derivatives retrieved from the CSD indicates that 83–97% of Hirshfeld surface areas in this class of compounds are due to H···H, H···π, H···O, and H···Cl/Br contacts.
We have fabricated by pulse laser deposition very thin (∼5-7 nm) and thick (∼27-408 nm) films of composition Fe66B24Nb4Ni6 on silicon and quartz substrates respectively, and studied their magnetic and magneto-optic properties at room temperature. We find that the thicker films on silicon can be tuned by appropriate thermal annealing to exploit soft magnetic characteristics with low HC, and high MS values. The magnetic hysteretic loops of the as-deposited thicker films on silicon substrates show two interesting characteristics: 1) increase in the coercivity with the film thickness and 2) the onset of a two stage process during the approach to magnetic saturation. The initial in-plane characteristic of the hysteresis loop is followed by a linear anisotropic behavior between remanence and saturation- that changes into square soft-magnetic loops on decreasing the film thickness. By suitable annealing the intrinsic strain disappears at relatively low temperatures (≤200 oC); the thicker films can be tailored to exhibit a simple soft-magnetic square loop with low HC. The ∼5-7 nm films deposited on glass are transparent and have been investigated for their magneto-optic properties using Faraday rotation (FR) measurement technique. Very high values of FR in the range 4-20 deg/µm almost linearly dependent on the wavelength of light in the range 405-611 nm are observed. The observed high values of Faraday rotation over a wide range of wavelength of light are useful for the applications as magneto-optic sensors in the UV to visible range.
BANs are used in several smart and context-aware applications such as home-based health care , sports health management , entertainment , and military applications . These applications impose several processing, communication, and storage requirements on the sensors in the BAN. For example, data sensing and storage are extensively required for home-based health care, computation-intensive physiological signal and image processing is required for military and entertainment applications, and online processing and communication of sensed data are used in sports health monitoring. Chapters 2 and 3 describe several BAN applications and their requirements in detail.
Usability issues in BAN, which include the need for easy wearability, infrequent re-charging of the battery, and thermally safe operation, prevent the use of powerful general-purpose processors in BAN sensors. Hence, application-specific developments of sensor platforms are essential for BANs. This has given rise to a plethora of sensor platforms that are being used for several BAN applications. These platforms are heterogeneous and typically limited in their computational, communication, and storage requirements. Processors ranging from powerful Intel xScale to low-power Atmega 128, radios ranging from power-hungry Bluetooth to efficient ZigBee, and storage ranging from 256 kB to 2 GB flash are available in current sensor platforms. Given these diversities in application requirements and sensor-platform capabilities, implementing a BAN application has two dimensions:
(1) choosing or designing a sensor platform that is best suited for a given application and
(2) implementing the given application in the sensor platform with stringent resource limitations.
Environmental sustainability has been of increasing interest in designing any system in recent times. Computing systems usually contribute to this drive of sustainability from two different perspectives: (i) the energy perspective and (ii) the equipment-recycling perspective. Sections 6.1 and 6.2 describe these perspectives of sustainability of computing systems in general. All subsequent sections will focus on how to ensure sustainability for BANs from the energy perspective.
The energy perspective
Sustainability from the energy perspective, also referred to as energy-sustainability, has two main objectives: (i) reducing the carbon footprint from the power grid and (ii) reducing the need for battery replacement (for computing equipment running on limited-energy batteries). To ensure that both these objectives are attained, energy-sustainability can be described as the balance between the power required for computation and the power available from renewable or green energy sources (e.g., sources in the environment such as solar power). Ideally, if the power available from external renewable energy sources is more than the power required for computation then a power grid (or battery) might not be needed, and computation can be said to be energy-sustainable. However, in reality, both the available and the required power may vary over time. For example, solar power is available only during the day, but power may be required during the night (depending on the time-varying computing operations performed). In such a case, power may need to be extracted from a power grid (or battery) during the night, thus making computing operations unsustainable.
In this book, we mainly focus on the pervasive health-monitoring system (PHMS), where the BAN nodes act as medical devices. Stand-alone BANs are typically ineffective due to their low computation and storage capability and limited battery life, especially when used in a PHMS setting. Thus, in PHMSes a BAN is usually used in conjunction with high-end embedded devices such as the smart phone and cloud-based computational and storage resources. Figure 3.1 shows the basic hardware architecture of a PHMS with the BAN deployed on the human body, communicating to a smart phone, which has limited storage and higher computation capability. The smart phone in turn uses the cloud for further processing and storage related to diagnosis and other applications. There have been different implementations of this basic architecture of a PHMS, each assuming different capabilities of the BAN, smart phone, and cloud. From a survey of the health-monitoring applications available on the market (at the time of writing this book), three categories of PHMS implementations have been identified.
In the first category, the sensors are considered to be merely data-collection units with no computation and storage. The sensors are merely monitoring devices and are not approved as marketable medical devices by the FDA in the USA. The smart phone acts as the primary computation device; it performs signal processing on the physiological signals and displays results to the user. […]
A body area network (BAN) is a network consisting of a heterogeneous set of nodes that can sense, actuate, compute, and communicate with each other through a multihop wireless channel. A BAN collects, processes, and stores physiological (such as electrocardiogram (ECG) and blood pressure), activity (such as walking, running, and sleeping), and environmental (such as ambient temperature, humidity, and presence of allergens) parameters from the host's body and its immediate surroundings; and can even actuate treatment (such as drug delivery), on the basis of the data collected. BANs can be very useful in assisting medical professionals to make informed decisions about the course of the patient's treatment by providing them with continuous information about the patient's condition.
BANs belong to a much more generic class of device networks called wireless sensor networks (WSNs) . BANs evolved from WSNs through a series of intermediate steps whereby first the WSN concept was applied to personal devices such as laptops, phones, cameras, and printers. Such networks are called personal area networks (PANs) , or wireless PANs (WPANs) . From WPANs evolved BANs in which medical devices, such as pulse oximeters, and personal computing or auxiliary devices such as smart phones and retina prostheses [29, 30] were networked through the wireless channel and worn on the body. Devices were also implanted, such as pacemakers, which communicate through the body to an outside controller. In a hospital setting, BANs are networked with other in-hospital medical devices such as Holter monitors and medical data recorders to form medical device networks (MDNs)  for post-operative or intensive-care-unit (ICU) patient monitoring.
This chapter focuses on the various definitions, challenges, and approaches to BAN safety. Standard ISO 60601, a standard for medical devices, defines safety as the avoidance of unacceptable risks of hazards to the physical environment (i.e., to the patient) due to the operation of a medical device under normal or single-fault condition. Although this definition is akin to that for medical devices, it can be generally applicable to BANs as well, which are essentially networks of such devices. The standard further lists seven aspects of safety as follows.
Operational aspect. This aspect considers safety as the correct (and error-free) operation of the medical device, which might involve software, hardware, and electrical and mechanical operations, as well as the usage of medical devices in clinical processes (or medical scenarios).
Radiation aspect. This aspect of safety is geared towards ensuring that any radiation (e.g., X-ray radiation) from the device does not harm the patient.
Thermal aspect. This aspect of safety concerns the need to ensure that any heat dissipated because of medical-device operation and power consumption does not burn any part of the patient's body.
Biocompatibility. This aspect requires the materials used for the medical device to be compatible with the human body.
Software aspect. This aspect is essentially covered under the operational aspect; however, with the proliferation of software-enabled devices and sensors, special emphasis has been placed on correct operation of device software (e.g., code consistency and execution flow).
Mechanical aspect. This aspect principally requires that any actuation (e.g., the infusion process employed by an infusion pump) from the medical device does not cause harm to the body.
Electrical aspect. This aspect is intended to ensure that the device does not deliver any electrical shock to the body.
In this chapter, we focus on security for BANs. In particular, we present a new paradigm that uses environment coupling – a property inherent to BANs – for this purpose. However, before we delve into the details, we provide some general concepts and definitions pertaining to the notion of security, which we use throughout this chapter. Though the notion of security has many connotations, for the purposes of this book, we define it in the information-security context, as preventing unauthorized entities from viewing, accessing, or modifying data generated within a system. We use the term system in a generic sense to mean a computing system that takes an input, processes it, and provides an output.
In order to ensure information security within any system, five basic requirements need to be satisfied. (1) Data integrity ensures that all information generated and exchanged during the system's operation is accurate and complete without any alterations. (2) Data confidentiality ensures that all sensitive information generated within the system is disclosed only to those who are supposed to see it. (3) Authentication ensures that the system knows the identities of all the entities interacting with it, and vice versa. (4) Authorization ensures that any entity trying to access particular information from the system is able to access only that information to which it is entitled. (5) Availability ensures that any entity that uses the data and services and resources of the system is able to do so when required.