Weaving temporal and reliability aspects into a schema tapestry

In aspect-oriented programming (AOP) a cross-cutting concern is implemented in an aspect. An aspect weaver blends code from the aspect into a program’s code at programmer-specified cut points, yielding an aspect-enhanced program. In this paper, we apply some of the concepts from the AOP paradigm to data. Like code, data also has cross-cutting concerns such as versioning, security, privacy, and reliability. We propose modeling a cross-cutting data concern as a schema aspect. A schema aspect describes the structure of the metadata in the cross-cutting concern, identifies the types of data elements that can be wrapped with metadata, i.e., the cut points, and provides some simple constraints on the use of the metadata. Several schema aspects can be applied to a single data collection, though in this paper we focus on just two aspects: a reliability aspect and a temporal aspect. We show how to weave the schema for these two aspects together with the schema for the data into a single, unified schema that we call a schema tapestry. The tapestry guides the construction, interpretation, and validation of an aspect-enhanced data collection.     

Effect of nano-Al2O3 particles on the corrosion behavior of alkyd based waterborne coatings

A modification in the alkyd based waterborne coatings was studied with the addition of 0.05%, 0.1%, 0.2%, and 0.3% nano-Al₂O₃. Corrosion performance of the nano-composite coatings were evaluated by applying these nanocomposites on mild steel substrate and exposing them to salt spray, humidity, and accelerated weathering. Mechanical properties were studied by subjecting the coating to scratch and abrasion test. The results showed that, with an increase in the concentration of nano-Al₂O₃ there was an improvement in the corrosion resistance, UV resistance, and mechanical properties of the coatings indicating the positive effect of addition of nano-Al₂O₃ particles in the coatings. Further, the transparency of the coating was not altered, maintaining the optical clarity of the coating.     

Metasurface-Enabled Generation of Circularly Polarized Single Photons

Single photons carrying spin angular momentum (SAM), i.e., circularly polarized single photons generated typically by subjecting a quantum emitter (QE) to a strong magnetic field at low temperatures, are at the core of chiral quantum optics enabling nonreciprocal single-photon configurations and deterministic spin-photon interfaces. Here, a conceptually new approach to the room-temperature generation of SAM-coded single photons (SSPs) is described, which entails QE nonradiative coupling to surface plasmons being transformed, by interacting with an optical metasurface, into a collimated stream of SSPs with the designed handedness. Design, fabrication, and characterization of SSP sources, consisting of dielectric circular nanoridges with azimuthally varying widths deterministically fabricated on a dielectric-protected silver film around a nanodiamond containing a nitrogen-vacancy center, are reported. With properly engineered phases of QE-originated fields scattered by nanoridges, the outcoupled photons are characterized by a well-defined SAM (with the chirality >0.8) and high directionality (collection efficiency up to 92%).     

Three‐dimensional cylindrical design multiple‐input‐multiple‐output/diversity antenna with high isolation for wireless communication applications

In this article, a three‐port nonplanar multiple‐input‐multiple‐output/diversity antenna with very high isolation between the radiating elements is presented. To realize diversity from the proposed three‐dimensional (3‐D) antenna configuration, three monopole radiating elements are arranged at an angle of 120°. The isolation between the radiators is enhanced by using a multilayered cylindrical decoupling structure and defected ground structure (DGS). The DGS reduces the coupling due to surface waves while the cylindrical decoupling structure reduces the coupling due to space waves. The proposed antenna offers consistent pervasive connectivity in the wireless communication environment due to its 3‐D geometry with multiple radiating elements and good diversity performance. The prototype is fabricated and measured result shows that more than 42 dB isolation is obtained at the center frequency 1.45 GHz. An increment of 1.2 dBi in the antenna gain is also achieved by using DGS and decoupling structure arrangement. The proposed antenna can be easily placed inside the cylindrical housing or it can be integrated with the existing electronics chip, thus nullifying the requirement for dedicated location in the system.     

Compact 4 × 4 Proximity Coupled Microstrip Fed UWB Stepped Slot MIMO Antenna Having Triple Band Rejection

Wireless Personal Communications - The presented antenna is a novel highly isolated compact four-element Multiple Input Multiple Output (MIMO) antenna with common ground, which can reject three...     

MEASUREMENT OF WATER DIFFUSIVITY IN AQUEOUS LITHIUM BROMIDE AND LITHIUM CHLORIDE SOLUTIONS

A relatively simple method was employed for measurement of water diffusivity in aqueous lithium bromide and lithium chloride solutions. The twin bulb apparatus used for these measurements was developed using an analogy between this apparatus and the conventional diaphragm cell apparatus. Tritiated water (TOH) was used as a tracer for these experiments because of its chemical similarity and proximity to the molecular weight of water. High tracer activity used at the beginning of the experiments allowed the use of relatively shorter time duration for each experiment (s;≈ 20 h) and a quasi-steady state equation to calculate the diffusivity from the observed tracer activity data

Initially, the water diffusivity in lithium bromide solutions for concentrations varying from 0.5 M to 3 M (22.1 weight percent) was measured to obtain a comparison with published values. The lithium bromide concentration was further varied from 3 M to 11 M (57.4 weight percent) to obtain data in the concentration range usually employed in absorption cooling applications, which is near the solubility limit. The water diffusivity was found to vary with lithium bromide concentration, and to have a maximum of 16.7 × 10^-10m²/s at 4 M. These diffusivity values were also compared with those obtained using an equation proposed by Rosevaere etal. (1941) for nonideal solutions. The water diffusivity in lithium chloride solutions was measured at concentrations of 7 M (25.7 weight percent) and 8 M (28.87 weight percent) to obtain a comparison with published values. The lithium choride concentration was further varied from 8 M to 13 M (43.24) weight percent) to gather data beyond those of other researchers. Similar to the trend of water diffusivity in lithium bromide solutions, water diffusivity in lithium chloride solutions was also found to vary with concentration with a minimum of 6.2 × 10^-10m²/s near the solubility limit.     

A 0.18$$\upmu$$m CMOS voltage multiplier arrangement for RF energy harvesting

This work presents a two-stage voltage multiplier (VM) useful in RF energy harvesting based applications. The proposed circuit is based on the conventional differential drive rectifier, in which the input RF signal has been level shifted using a simple arrangement. This signal is then used to drive the next stage, which has been formed by using gate cross-coupled transistors. As a result, the load driving capability of the proposed architecture increases. The load in this work has been emulated in terms of a parallel RC circuit. The architecture has been implemented using standard 0.18 \(\mu\)m CMOS technology. The measurements of the two-stage conventional VM (CVM) and proposed VM circuits were performed at ISM frequencies 13.56, 433, 915 MHz and 2.4 GHz for R\(_L\) of values 1, 5, 10, 3 and 100 K\(\Omega\) with a fixed value of C\(_L\) equal to 20 pF. The performance evaluation has been done in terms of the power conversion efficiency (PCE) and average output DC voltage. The measured results show an improvement in PCE of 5% (minimum) for 13.56, 433 and 915 MHz frequencies, and up to 2% improvement for a frequency value of 2.4 GHz at the targeted load condition of 5 K\(\Omega ||\)20 pF, when compared with the measured results of the CVM circuit.     

Phylogenetic Studies,Gene Cluster Analysis,and Enzymatic Reaction Support Anthrahydroquinone Reduction as the Physiological Function of Fungal 17β‐Hydroxysteroid Dehydrogenase

17β‐Hydroxysteroid dehydrogenase (17β‐HSDcl) from the filamentous fungus Curvularia lunata (teleomorph Cochliobolus lunatus) catalyzes NADP(H)‐dependent oxidoreductions of androgens and estrogens. Despite detailed biochemical and structural characterization of 17β‐HSDcl, its physiological function remains unknown. On the basis of amino acid sequence alignment, phylogenetic studies, and the recent identification of the physiological substrates of the homologous MdpC from Aspergillus nidulans and AflM from Aspergillus parasiticus, we propose an anthrahydroquinone as the physiological substrate of 17β‐HSDcl. This is also supported by our analysis of a secondary metabolite biosynthetic gene cluster in C. lunata m118, containing 17β‐HSDcl and ten other genes, including a polyketide synthase probably involved in emodin formation. Chemoenzymatic reduction of emodin by 17β‐HSDcl in the presence of sodium dithionite verified this hypothesis. On the basis of these results, the involvement of a 17β‐HSDcl in the biosynthesis of other anthrahydroquinone‐derived natural products is proposed; hence, 17β‐HSDcl should be more appropriately referred to as a polyhydroxyanthracene reductase (PHAR).     

Studies of interaction of amines with TOPO/TOP capped CdSe quantum dots: Role of crystallite size and oxidation potential

This work reports the interaction of aliphatic (triethyl amine, butyl amine) and aromatic amines (PPD, aniline) with CdSe quantum dots of varied sizes. The emission properties and lifetime values of CdSe quantum dots were found to be dependent on the oxidation potential of amines and crystallite sizes. Smaller CdSe quantum dots (size 5 nm) ensure better surface coverage of amines and hence higher quenching efficiency of amines could be realized as compared to larger CdSe quantum dots (size 14 nm). Heterogeneous quenching of amines due to the presence of accessible and inaccessible set of CdSe fluorophores is indicated. PPD owing to its lowest oxidation potential (0.26 V) has been found to have higher quenching efficiency as compared to other amines TEA and aniline having oxidation potentials 0.66 and >1.0 V, respectively. Butyl amine on the other hand, plays a dual role: its post-addition acts as a quencher for smaller and enhances emission for larger CdSe quantum dots, respectively. The beneficial effect of butyl amine in enhancing emission intensity could be attributed to enhance capping effect and better passivation of surface-traps.