An efficient parity detection technique using the two-moduli set {2 − 1, 2 + 1}

Lu and Chiang used both the table lookup and fractional number approaches to discover the parity of an RNS number. To eliminate the need for table space and time for computing fractions, a two-moduli set {2^h − 1, 2^h + 1} is used to speed up the technique proposed by Lu and Chiang. Based on this modified two-moduli set, it is found that the parity of an RNS number X = (x₁, x₂) is if x₁ ? x₂. On the contrary, if x₁ < x₂, the parity of X is .     

Fast, prime factor, discrete Fourier transform algorithms over GF(2) for 8 ? m ? 10

In this paper it is shown that Winograd’s algorithm for computing convolutions and a fast, prime factor, discrete Fourier transform (DFT) algorithm can be modified to compute Fourier-like transforms of long sequences of 2^m − 1 points over GF(2^m), for 8 ? m ? 10. These new transform techniques can be used to decode Reed-Solomon (RS) codes of block length 2^m − 1. The complexity of this new transform algorithm is reduced substantially from more conventional methods. A computer simulation verifies these new results.     

A CO2 sensor based upon a continuous-wave thermoelectrically-cooled quantum cascade laser

A CO₂ sensor based upon a continuous-wave thermoelectrically-cooled distributed feedback quantum cascade laser operating between 2305 and 2310 cm⁻¹ and a 54.2 cm long optical cell has been developed. Two approaches for direct absorption spectroscopy have been evaluated and applied for monitoring of the CO₂ concentration in gas lines and ambient laboratory air. In the first approach optical transmittance was derived from the single channel laser intensity, whilst in the second approach a ratio of signal and reference laser intensities (balanced detection) was used. The optimum residual absorption standard deviation was estimated to be 1.9 × 10⁻⁴ for 100 averages of 1 ms duration and 0.1 cm⁻¹ scans over the P(46) CO₂ absorption line of the ν₃ vibrational band at 2306.926 cm⁻¹. A CO₂ detection limit (1 standard deviation) of 36 ppb was estimated for 0.1 s average and balanced detection.     

An assessment of the black ocean pixel assumption for MODIS SWIR bands

Recent studies show that an atmospheric correction algorithm using shortwave infrared (SWIR) bands improves satellite-derived ocean color products in turbid coastal waters. In this paper, the black pixel assumption (i.e., zero water-leaving radiance contribution) over the ocean for the Moderate Resolution Imaging Spectroradiometer (MODIS) SWIR bands at 1240, 1640, and 2130 nm is assessed for various coastal ocean regions. The black pixel assumption is found to be generally valid with the MODIS SWIR bands at 1640 and 2130 nm even for extremely turbid waters. For the MODIS 1240 nm band, however, ocean radiance contribution is generally negligible in mildly turbid waters such as regions along the U.S. east coast, while some slight radiance contributions are observed in extremely turbid waters, e.g., some regions along the China east coast, the estuary of the La Plata River. Particularly, in the Hangzhou Bay, the ocean radiance contribution at the SWIR band 1240 nm results in an overcorrection of atmospheric and surface effects, leading to errors of MODIS-derived normalized water-leaving radiance at the blue reaching ~ 0.5 mW cm^− 2 μm^− 1 sr^− 1. In addition, we found that, for non-extremely turbid waters, i.e., the ocean contribution at the near-infrared (NIR) band < ~ 1.0 mW cm^− 2 μm^− 1 sr^− 1, there exists a good relationship in the regional normalized water-leaving radiances between the red and the NIR bands. Thus, for non-extremely turbid waters, such a red-NIR radiance relationship derived regionally can possibly be used for making corrections for the regional NIR ocean contributions without using the SWIR bands, e.g., for atmospheric correction of ocean color products derived from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS).     

A (4n − 9)/3 diagnosis algorithm on n-dimensional cube network

As a generalization of the precise and pessimistic diagnosis strategies of system-level diagnosis of multicomputers, the t/k diagnosis strategy can significantly improve the self-diagnosing capability of a system at the expense of no more than k fault-free processors (nodes) being mistakenly diagnosed as faulty. In the case k ? 2, to our knowledge, there is no known t/k diagnosis algorithm for general diagnosable system or for any specific system. Hypercube is a popular topology for interconnecting processors of multicomputers. It is known that an n-dimensional cube is (4n − 9)/3-diagnosable. This paper addresses the (4n − 9)/3 diagnosis of n-dimensional cube. By exploring the relationship between a largest connected component of the 0-test subgraph of a faulty hypercube and the distribution of the faulty nodes over the network, the fault diagnosis of an n-dimensional cube can be reduced to those of two constituent (n − 1)-dimensional cubes. On this basis, a diagnosis algorithm is presented. Given that there are no more than 4n − 9 faulty nodes, this algorithm can isolate all faulty nodes to within a set in which at most three nodes are fault-free. The proposed algorithm can operate in O(N log₂ N) time, where N = 2ⁿ is the total number of nodes of the hypercube. The work of this paper provides insight into developing efficient t/k diagnosis algorithms for larger k value and for other types of interconnection networks.     

Microfabricated microfluidic fuel cells

We demonstrate high performance microfuel cells (μFC) operating at room temperature. The smallest μFC has a reaction surface of 0.11 cm² and has an output power density equal to 22.9 mW cm⁻². Methanol and air are supplied using microchannels etched into silicon wafers using microfabrication techniques which can accurately determine the μFC surface and the microchannel dimensions. The insertion of a novel hydrophilic fibrous layer into the anode diffusion layer stack produces 9.25 mW cm⁻² for an input fuel flow rate of 550 nL min⁻¹. The benefits of size-scaling and architecture optimization in μFC are demonstrated. Our observations and conclusions are by no means unique to methanol μFC but could be applied to other microfluidic liquid fuel μFC based on, e.g. microbial fuel cells, bio-ethanol and glucose solution.     

In2O3 + xBaO (x = 0.5-5 at.%) - A novel material for trace level detection of NOx in the ambient

Indium oxide (In₂O₃) doped with 0.5-5 at.% of Ba was examined for their response towards trace levels of NO_x in the ambient. Crystallographic phase studies, electrical conductivity and sensor studies for NO_x with cross interference for hydrogen, petroleum gas (PG) and ammonia were carried out. Bulk compositions with x ≤ 1 at.% of Ba exhibited high response towards NO_x with extremely low cross interference for hydrogen, PG and ammonia, offering high selectivity. Thin films of 0.5 at.% Ba doped In₂O₃ were deposited using pulsed laser deposition technique using an excimer laser (KrF) operating at a wavelength of (λ) 248 nm with a fluence of ∼3 J/cm² and pulsed at 10 Hz. Thin film sensors exhibited better response towards 3 ppm NO_x quite reliably and reproducibly and offer the potential to develop NO_x sensors (Threshold limit value of NO₂ and NO is 3 and 25 ppm, respectively).     

Detecting very small quantity of molecular probes in solution using nano-mechanically made Au-cavities array with SERS-active effect

Well-ordered nano-mechanically made Au-cavities array (nAu) is tailored as a functional surface with high density tip-to-tip cavities, adjustable indentation depths, and a number of edges within the nanostructures. In this study, the nAu was fabricated by a physical way and utilized as a characterization tool with the advantage of preventing samples from chemical or residual contaminations. Two types of molecular probe solutions: 5,5′-dithio-bis-(2-nitrobenzoic acid) (DTNB) and Rhodamine 6G (R6G) were evaluated. For DTNB solution, the chemically adsorbed monolayer was formed upon the nAu, which resulted in the effect of surface enhanced Raman scattering (SERS), mainly induced by the combined chemical and electromagnetic effects. Within the range of 1 × 10⁻²³ to 3.2 × 10⁻²² mole, Raman intensity and the quantity of DTNB molecules exhibited a sharp exponential relationship. For R6G solution within the equivalent nAu and the identical range, the relationship exhibited nearly linear; however, within an extended range of 1 × 10⁻²³ to 3.2 × 10⁻²¹ mole, a moderate exponential relationship was obtained. The enhancement factors for detecting DTNB and R6G solutions using the nAu could be optimized to 1.62 × 10⁸ and 4.60 × 10⁷, respectively.     

A coral-like macroporous gold-platinum hybrid 3D electrode for enzyme-free glucose detection

We are introducing a macroporous Au-Pt hybrid 3D electrode to be used for enzyme-free glucose detection. The proposed hybrid electrode was fabricated with a three dimensional structure by electroplating platinum nanoparticles onto the surface of the coral-like macroporous Au. It was then physically analyzed by using field emission scanning electron microscopy (FESEM). The porosity and window pore size of the macroporous Au electrode were 50% and 100-300 nm, respectively. The diameters of the Pt nanoparticles ranged from 10 to 15 nm. Through cyclic voltammograms in a 1 M sulfuric acid solution, we confirmed that the hybrid electrode exhibited a much larger surface activation area with a roughness factor (RF) of 2024.7 than the macroporous Au electrode with a roughness of 46.07. The highly improved surface activation area was caused by the electroplated Pt nanoparticles. The hybrid electrode exhibited a much stronger electrocatalytic activity due to glucose oxidation than the macroporous Au electrode. At 0.4 V, it responded linearly to the glucose up to 20 mM in a neutral media with a detection limit of 0.025 mM and detection sensitivity of 39.53 μA mM⁻¹ cm⁻² without being affected by interfering species. It also showed a stable recovery response to the step changes of the glucose concentration.     

Remote sensing of water quality in an Australian tropical freshwater impoundment using matrix inversion and MERIS images

The purpose of this study was to investigate how semi-analytical inversion techniques developed for the remote sensing of water quality parameters (chlorophyll a, tripton and coloured dissolved organic matter (CDOM)) in inland waters could be adapted or improved for application to Australian tropical and sub-tropical water bodies. The Matrix Inversion Method (MIM) with a semi-analytic model of the anisotropy of the in-water light field was applied to MERIS images of Burdekin Falls Dam, Australia, a tropical freshwater impoundment. Specific attention was required to improve the atmospheric correction of the MERIS data. The performance of the conventional three band exact solution of the MIM was compared to that of over-determined solutions that used constant and differential weighting for each sensor band.The results of the application of the MIM algorithm showed that the best weighting scheme had a mean chlorophyll a retrieval difference of 1.0 μgl^− 1, the three band direct matrix inversion scheme had a mean difference of 4.2 μgl^− 1 and the constant weight scheme had a mean difference of 5.5 μgl^− 1. For tripton, the best performed weighting scheme had a mean difference of 1.2 mgl^− 1, the three band scheme had a mean difference of 3.4 mgl^− 1 and the constant weight scheme had a mean difference of 1.8 mgl^− 1. For the CDOM retrieval, the mean difference was found to be 0.12 m^− 1 for the best performed weighting scheme, 0.25 m^− 1 for the three band scheme and 0.52 m^− 1 for the constant weight scheme. It was found that significant improvements in the accuracy and precision of retrieved water quality parameter values can be obtained by using differentially weighted, over-determined systems of equations, rather than exact solutions. These more reliable estimates of water quality parameters will allow water resource managers to improve their monitoring regimes.     

Development of a dehydrogenase-based glucose anode using a molecular assembly composed of nile blue and functionalized SWCNTs and its applications to a glucose sensor and glucose/O2 biofuel cell

A simple and new way to immobilize glucose dehydrogenase (GDH) enzyme onto nile blue (NB) covalently assembled on the surface of functionalized single-walled carbon nanotubes (f-SWCNTs) modified glassy carbon (GC) electrode (GDH/NB/f-SWCNTs/GC electrode) was described. The GDH/NB/f-SWCNTs/GC electrode possesses promising characteristics as glucose sensor; a wide linear dynamic range of 100-1700 μM, low detection limit of 0.3 μM, fast response time (1-2 s), high sensitivity (14 μA cm⁻² mM⁻¹), anti-interference ability and anti-fouling. Moreover, the performance of the GDH/NB/f-SWCNTs/GC bioanode was successfully tested in a glucose/O₂ biofuel cell. The maximum power density delivered by the assembled glucose/O₂ biofuel cell could reach 32.0 μW cm⁻² at a cell voltage of 0.35 V with 40 mM glucose. The present procedure can be applied for preparing a potential platform to immobilize different enzymes for various bioelectrochemical applications.     

Potentiometric solid-state sensor for DO measurement in water using sub-micron Cu0.4Ru3.4O7 + RuO2 sensing electrode

The dissolved oxygen (DO) sensing electrode (SE) concept utilizing sub-micron-sized ruthenium oxide (RuO₂), doped with other nanostructured oxides, has been extended to investigate the possibility of employing copper (II) oxide (Cu₂O) as a dopant in order to improve sensor's characteristics and meet long term antifouling needs for SEs. In this work, a thin-film SE made of RuO₂ was constructed on the alumina sensor substrate, and a range of dopants and their concentrations was added to it in order to optimize SE properties. The Cu₂O-doped RuO₂ SE had shown a linear response to DO between 0.5 and 8.0 ppm at various temperatures, with two sensitivity maxima of 47.4 and 46.0 mV per decade for Cu₂O concentrations of 10 and 20 mol%, respectively. The maximum sensitivity for Cu_0.4Ru_3.4O₇ + RuO₂-SE was obtained at a dopant concentration of 10%. Selectivity measurements revealed that the presence of Ca²⁺, Mg²⁺, Li⁺, Na⁺, NO³⁻, PO₄³⁻, SO₄²⁻, F⁻, K⁺ and Cl⁻ in the solution had no significant effect on the sensor's emf. The sensor allows overcoming the problem of an insufficient selectivity of semiconductor-based water sensors. It was also found that the doping of RuO₂-SE by Cu₂O allowed it to function at full capacity in a natural outdoor water body with no obvious effects of biofouling.     

Comments on “Generalised finite Radon transform for N × N images”

In Kingston and Svalbe [1], a generalized finite Radon transform (FRT) that applied to square arrays of arbitrary size N × N was defined and the Fourier slice theorem was established for the FRT. Kingston and Svalbe asserted that “the original definition by Matúš and Flusser was restricted to apply only to square arrays of prime size,” and “Hsung, Lun and Siu developed an FRT that also applied to dyadic square arrays,” and “Kingston further extended this to define an FRT that applies to prime-adic arrays”. It should be said that the presented generalized FRT together with the above FRT definitions repeated the known concept of tensor representation, or tensor transform of images of size N × N which was published earlier by Artyom Grigoryan in 1984-1991 in the USSR. The above mentioned “Fourier slice theorem” repeated the known tensor transform-based algorithm of 2-D DFT [5-11], which was developed for any order N₁ × N₂ of the transformation, including the cases of N × N, when N = 2^r, (r > 1), and N = L^r, (r ≥ 1), where L is an odd prime. The problem of “over-representation” of the two-dimensional discrete Fourier transform in tensor representation was also solved by means of the paired representation in Grigoryan [6-9].     

Improved hydrogen-sensing performance of a Pd/GaN Schottky diode with a surface plasma treatment approach

The improved hydrogen-sensing performance of a Pd/GaN Schottky diode with a simple surface treatment is demonstrated. The studied device with an inductively coupled-plasma (ICP)-treatment shows both the good sensitivity and fast response. A high hydrogen detection sensing response of 2.05 × 10⁵, under exposing to a 10,000 ppm H₂/air gas at room temperature, is obtained. It is found that, due to the increased surface roughness, more hydrogen atoms are adsorbed on the active layer which leads to the substantial increase of current change. In addition, the studied device shows a stable and widespread reverse voltage operating regime (−0.3 to −3 V) and a fast response about of 2.9 s. Therefore, this simple surface treatment approach gives the promise for hydrogen sensing applications.     

Analyte selective response in solution-deposited tetrabenzoporphyrin thin-film field-effect transistor sensors

Organic thin film transistor (OTFT) chemical sensors rely on the specific electronic structure of the organic semiconductor (OSC) film for determining sensor stability and response to analytes. The delocalized electronic structure is influenced not only by the OSC molecular structure, but also the solid state packing and film morphology. Phthalocyanine (H₂Pc) and tetrabenzoporphyrin (H₂TBP) have similar molecular structures but different film microstructures when H₂Pc is vacuum deposited and H₂TBP is solution deposited. The difference in electronic structures is evidenced by the different mobilities of H₂TBP and H₂Pc OTFTs. H₂Pc has a maximum mobility of 8.6 × 10⁻⁴ cm² V⁻¹ s⁻¹ when the substrate is held at 250 °C during deposition and a mobility of 4.8 × 10⁻⁵ cm² V⁻¹ s⁻¹ when the substrate is held at 25 °C during deposition. Solution deposited H₂TBP films have a mobility of 5.3 × 10⁻³ cm² V⁻¹ s⁻¹, which is consistent with better long-range order and intermolecular coupling within the H₂TBP films compared to the H₂Pc films. Solution deposited H₂TBP also exhibits a textured film morphology with large grains and an RMS roughness 3-5 times larger than H₂Pc films with similar thicknesses. Despite these differences, OTFT sensors fabricated from H₂TBP and H₂Pc exhibit nearly identical analyte sensitivity and analyte response kinetics. The results suggest that while the interactions between molecules in the solid state determine conductivity, localized interactions between the analyte and the molecular binding site dominate analyte binding and determine sensor response.     

Direct electrochemistry of cytochrome P450 6A1 in mimic bio-membrane and its application for pesticides sensing

The direct electrochemistry of house fly cytochrome P4506A1 (CYP6A1) confined in dioctadecyl dimethyl ammonium bromide (DDAB) film was achieved. The immobilized CYP6A1 displayed a pair of redox peaks with a formal potential of −0.36 mV in pH 7.0 O₂-free phosphate buffers at scan rate of 1 V s⁻¹ and the direct electron transfer of CYP6A1 was characterized by voltammetry. The CYP6A1 in the DDAB film retained its bioactivity and could catalyze the reduction of dissolved oxygen. Upon addition of its substrate aldrin or heptachlor to the air-saturated solution, the reduction peak current of dissolved oxygen increased, which indicates the catalytic behavior of CYP6A1 to its substrates. By amperometry a calibration linear range was obtained to be 9.08 × 10⁻⁶-4.54 × 10⁻⁵ mol L⁻¹ with a sensitivity of 80 μA mM⁻¹ for aldrin or 8.91 × 10⁻⁶-4.46 × 10⁻⁵ mol L⁻¹ with a sensitivity of 66 μA mM⁻¹ for heptachlor. The apparent Michaelis-Menten constant for the electrocatalytic activity of CYP6A1 was found to be 7.468 × 10⁻⁵ mol L⁻¹ for aldrin and 4.316 × 10⁻⁵ mol L⁻¹ for heptachlor. The bioelectrocatalytic products were analysed using gas chromatography (GC) and electron ionization-mass spectrometry (EI-MS). The results confirmed that epoxidation was the main pathways of CYP6A1-mediated organochlorine pesticides oxidation.     

High strain electromechanical actuators based on electrodeposited polypyrrole doped with di-(2-ethylhexyl)sulfosuccinate

The low-voltage electromechanical actuation of polypyrrole (PPy) doped with di-(2-ethylhexyl)sulfosuccinate (DEHS) has been investigated. The PPy-DEHS has been prepared both chemically (cast as films from solution) and by more conventional electrochemical polymerization. Very large strains of ∼30% were obtained during slow-scan redox cycling of the electrochemically prepared PPy-DEHS films. In constrast, PPy-DEHS films cast from solutions of the chemically polymerized polymer gave actuation strains of ∼2.5%. The polymerization method was also found to have a significant effect on the structure, conductivity and mechanical properties of the PPy-DEHS materials. The conductivity of the electrochemically polymerized PPy-DEHS was 75 S cm⁻¹, considerably higher than that found for the chemically derived polymer (7 S cm⁻¹). The structure of the PPy-DEHS was further elucidated from UV-vis, Raman and FT-IR spectral studies which indicated that the conjugation length of the PPy could be increased significantly by varying the polymerization method. Films obtained by casting chemically prepared PPy-DEHS showed higher modulus (2.3 GPa) than electropolymerized PPy-DEHS (0.6 GPa), but were more brittle. Both materials were electroactive in acetonitrile/water electrolyte. The higher actuation strain observed in the electrochemically prepared films was attributed to a more open molecular structure (as indicated by the lower modulus) allowing for easier ion diffusion and a higher conductivity allowing easier charge transfer.     

An electrochemical biosensor for determination of hydrogen peroxide using nanocomposite of poly(methylene blue) and FAD hybrid film

An electrochemical biosensor for determination of hydrogen peroxide (H₂O₂) has been developed by the hybrid film of poly(methylene blue) and FAD (PMB/FAD). The PMB/FAD hybrid film was performed in PBS (pH 7) containing methylene blue and FAD by cyclic voltammetry. Repeatedly scanning potential range of −0.6-1.1 V, FAD was immobilized on the electrode surface by electrostatic interaction while methylene blue was electropolymerized on electrode surface. This modified electrode was found surface confined and pH dependence. It showed good electrocatalytic reduction for H₂O₂, KBrO₃, KIO₃, and NaClO as well as electrocatalytic oxidation for NADH. At an applied potential of −0.45 V vs. Ag/AgCl, the sensor showed a rapid and linear response to H₂O₂ over the range from 0.1 μM to 960 μM, with a detection limit of 0.1 μM and a significant sensitivity of 1109 μA mM⁻¹ cm⁻² (S/N = 3). It presented excellent stability at room temperature, with a variation of response current less than 5% over 30 days.     

Low-power subthreshold to above threshold level shifters in 90 nm and 65 nm process

In this paper we present low power level shifters in the 90 nm (general purpose) and 65 nm (low power) technology nodes capable of converting subthreshold voltage signals to above threshold voltage signals. The level shifters make use of the MTCMOS design technique which gives more design flexibility, especially in low power systems. Post layout simulations indicate static power consumption down to 1 nW and 83 pW in the 90 nm and 65 nm process respectively. Energy consumption per transition is recorded to be below 30 fJ in both processes, orders of magnitude lower then other published level shifter implementations. Propagation delay is found to be as low as 32 ns for subthreshold logic high input signals of 180 mV. The functionality of the level shifters is verified across process-, mismatch- and temperature variations between −40 °C and 150 °C. Minimum input voltage attainable while maintaining robust operation is found to be around 180 mV at operational frequencies above 1 MHz in the 90 nm process, and 350 mV at operational frequencies above 500 kHz in the 65 nm process. The level shifters employ an enable/disable feature, allowing for power saving when the level shifter is not in use.     

Poly(brilliant cresyl blue) electrogenerated on single-walled carbon nanotubes modified electrode and its application in mediated biosensing system

Single-walled carbon nanotubes (SWCNTs) functionalized with carboxylic acid groups were cast to glassy carbon electrode (GCE) to construct a three-dimensional nano-micro structured scaffold. Brilliant cresyl blue (BCB) was electropolymerized on the above-mentioned SWCNTs/GCE using continuous cycling between −0.7 and 0.9 V vs. SCE. PolyBCB yielded on SWCNTs/GCE exhibited the enhanced electrochemical redox behavior compared with that electrogenerated on bare GCE. The apparent surface coverage of PolyBCB obtained by SWCNTs/GCE was at least 10 times higher than that obtained by bare GCE, namely 4.8 × 10⁻⁹ and 3.6 × 10⁻¹⁰ mol cm⁻². The cyclic voltammograms recorded by PolyBCB/SWCNTs/GCE exhibited well-defined two peaks located at −0.25 V and −0.06 V, respectively, with a surface-controlled mechanism. In addition, morphologies of PolyBCB electrogenerated on GCE and SWCNTS/GCE were characterized by atomic force microscopy. Finally, this proposed PolyBCB/SWCNTs/GCE was used in the construction of the second-generation biosensors to hydrogen peroxide and glucose, with the enhanced analytical performance.