High Substrate Research Articles

A tightly coupled dipole array used for radiation power improvement on finite radiation aperture

Radiation power of an electromagnetic wave plays a decisive role in its transmission distance. Traditionally, the radiation power can be improved by expanding the radiation aperture size of the antenna array or increasing input power of the unit cell. However, the radiation aperture size is always restricted by assembly space. The input power improvement of the unit cell is always limited by the signal source. It is difficult to improve radiation power on a finite radiation aperture. However, the radiation power on a finite radiation aperture is related closely to the number of antenna elements and the radiation efficiency of the antenna array. It is useful to arrange more elements and improve radiation efficiency of the antenna array to improve the radiation power on a finite radiation aperture. Wideband wide-angle scanning phased array is able to make full use of a finite radiation aperture. The wide-angle scanning properties make it possible for the radiated power to cover a wide area. In this paper, a compact wideband wide-angle scanning tightly coupled dipole array (TCDA) is proposed. A high permittivity substrate and compact wideband balun are used for miniaturizing the antenna array. The period of the unit cell is only 0.144<i>λ</i><sub>high</sub> × 0.144<i>λ</i><sub>high</sub> (<i>λ</i><sub>high</sub> is the wavelength at the highest operation frequency in free space). Parameters of the balun are optimized to improve impedance matching between the balun and the antenna array. Two bilateral frequency selective surfaces (FSSs) are used to replace traditional dielectric superstrate to improve the impedance matching between the antenna array and free space. A low-loss dielectric substrate is used to reduce dielectric loss of the antenna array. In these ways, the radiation efficiency is greatly improved. The simulation results show that the proposed antenna array operates at 1.7–5.4 GHz (3.2:1) while scanning up to 65° in the E plane, 45° in the H plane and 60° in the D plane with following a rigorous impedance matching criterion (active VSWR < 2). A 16 × 16 prototype array is fabricated and measured. Good agreement is achieved between the simulation results and the measurement results. Compared with the designs in the literature, the proposed antenna array has an excellent performance in radiation power on a finite radiation aperture.

The effect of heavy metals on thiocyanate biodegradation by an autotrophic microbial consortium enriched from mine tailings

Bioremediation systems represent an environmentally sustainable approach to degrading industrially generated thiocyanate (SCN−), with low energy demand and operational costs and high efficiency and substrate specificity. However, heavy metals present in mine tailings effluent may hamper process efficiency by poisoning thiocyanate-degrading microbial consortia. Here, we experimentally tested the tolerance of an autotrophic SCN−-degrading bacterial consortium enriched from gold mine tailings for Zn, Cu, Ni, Cr, and As. All of the selected metals inhibited SCN− biodegradation to different extents, depending on concentration. At pH of 7.8 and 30 °C, complete inhibition of SCN− biodegradation by Zn, Cu, Ni, and Cr occurred at 20, 5, 10, and 6 mg L−1, respectively. Lower concentrations of these metals decreased the rate of SCN− biodegradation, with relatively long lag times. Interestingly, the microbial consortium tolerated As even at 500 mg L−1, although both the rate and extent of SCN− biodegradation were affected. Potentially, the observed As tolerance could be explained by the origin of our microbial consortium in tailings derived from As-enriched gold ore (arsenopyrite). This study highlights the importance of considering metal co-contamination in bioreactor design and operation for SCN− bioremediation at mine sites.Key points• Both the efficiency and rate of SCN−biodegradation were inhibited by heavy metals, to different degrees depending on type and concentration of metal.• The autotrophic microbial consortium was capable of tolerating high concentrations of As, potential having adapted to higher As levels derived from the tailings source.

Infections are associated with a higher substrate provision in icu patients: An icu nutritionday analysis

Infections are associated with a higher substrate provision in icu patients: An icu nutritionday analysis

CPW-Fed Wide Band Micro-machined Fractal Antenna with Band-notched Function

In this paper, a straightforward yet effective design methodology to design wideband antenna with band notched characteristics has been proposed. Sierpinski carpet fractal geometry has been used to realize the antenna structure. Co-planar waveguide feed is used with a novel structure to achieve larger impedance bandwidth and band notching characteristics. Proposed antenna is designed using High Frequency Structure Simulator (HFSS) on a low cost FR4 substrate (ɛr=4.4) which resonates at three frequencies 1.51 GHz (1.19-2.06GHz), 6.53 GHz and 8.99 GHz (4.44-9.54 GHz) while a band is notched at 10.46 GHz (9.32-11.92 GHz). The proposed antenna has an electrical dimension of 0.36 λm× 0.24 λm, here λm is the wavelength with respect to lowest resonating frequency of the antenna. The resonating and radiation characteristics of the antenna are verified experimentally. Further, investigations are made to achieve easy integration of the antenna to the monolithic microwave integrated circuits. For that the antenna has been designed on micro-machined high index Silicon substrate which improve matching and gain of the antenna. The results of the micro-machined Sierpinski carpet fractal antenna are highly convincing over the conventional FR4 based antenna.

A novel thermostable alkaline histamine oxidase from Glutamicibacter sp. N1A3101, induced by histamine and its analogue betahistine

Biogenic amines (BAs) are low molecular weight organic bases formed by natural amino acids decarboxylation and trigger an array of toxicological effects in humans and animals. Bacterial amine oxidases enzymes are determined as practical tools to implement the rapid quantification of BAs in foods. Our study set out to obtain a new efficient, amine oxidase enzyme for developing new enzyme-based quantification of histamine. The soils from different sources were screened using histamine as sole carbon and nitrogen sources, and histamine oxidase producing bacteria were selected and identified using specific primers for histamine oxidase (HOD) gene. The HOD gene of six strains, out of 26 isolated histamine-utilizing bacteria, were amplified using our designed primers. The HOD enzyme from Glutamicibacter sp. N1A3101, isolated from nettle soil, was found to be thermostable and showed the highest substrate specificity toward the histamine and with no detected activity in the presence of putrescine, cadaverine, spermine, and spermidine. Its oxidation activity toward tyramine was lower than other HOD reported so far. The isolated enzyme was stable at 60 °C for 30 min and showed pH stability ranging from 6 to 9. Furthermore, we indicated the induction of identified HOD activity in the presence of betahistine as well, with nearly equal efficiency and without the consumption of the substrate.

Rapid Thermal Annealing for Surface Optimisation of ZnO Substrates for MBE-Grown Oxide Two-Dimensional Electron Gases

Two-dimensional electron gases (2DEGs) at the ZnO/ZnMgO interface are promising for applications in spintronics and quantum computing due to the combination of low spin-orbit coupling and high electron mobility. Growing high mobility 2DEGs requires high quality substrates with low impurity densities. In this work we demonstrate a ZnO substrate sample treatment combining high temperature rapid thermal annealing and chemical etching to improve the surface quality for the subsequent growth of 2DEGs. This process enables the growth of a 2DEG with low-temperature mobility of 4.8×104 cm2V−1s−1. An unannealed control sample shows a scattering rate at least three times greater than the annealed sample.

Analysis of dielectric resonator antenna with its equivalent R, L, C circuit modelling

Equivalent R, L, C circuit is realized for DRA (dielectric resonator antenna) with mathematical solution. Resonant frequency, reflection coefficient, impedance and quality factor have been evaluated along with fundamental and higher order resonant modes. The relationship between quality factor, impedance and resonance have been established. Solution of DRA has been obtained with MATLAB and HFSS software. DRA experimentations based on prototypes has been completed. Measured and simulated results for reflection coefficient and radiation pattern have been compared and found to be in close proximity. Use of high permittivity substrates in DRA increases the quality factor whereas low permittivity substrates are in contrast. More number of parallel R, L, C networks in cascade increase the quality factor as well as input impedance. Study of DRA impedance, reflection coefficient and radiated fields have been investigated using R, L, C parallel circuits connected in cascaded form. Power flow and radiations have been rigorously analysed with mathematical formulations.

Cyclodextrinase from Thermococcus sp expressed in Bacillus subtilis and its application in the preparation of maltoheptaose

BackgroundMaltoheptaose as malto-oligosaccharides with specific degree of polymerization, has wide applications in food, medicine and cosmetics industries. Currently, cyclodextrinase have been applied as prepared enzyme to prepare maltoheptaose. However, the yield and proportion of maltoheptaose was lower, which is due to limited substrate and product specificity of cyclodextrinase (CDase). To achieve higher maltoheptaose yield, cyclodextrinase with high substrate and product specificity should be obtained.ResultsIn this study, cyclodextrinase derived from Thermococcus sp B1001 (TsCDase) was successfully expressed and characterized in Bacillus subtilis for the first time. The specific activity of TsCDase was 637.95 U/mg under optimal conditions of 90 °C and pH 5.5, which exhibited high substrate specificity for cyclodextrins (CDs). When the concentration of β-CD was 8%, the yield of maltoheptaose achieved by TsCDase was 82.33% across all reaction products, which exceeded the yields of maltoheptaose in other recent reports. Among malto-oligosaccharides generated as reaction products, maltoheptaose was present in the highest proportion, about 94.55%.ConclusionsThis study provides high substrate and product specificity of TsCDase. TsCDase is able to prepare higher yield of maltoheptaose through conversion of β-CD in the food industry.

Wettability, Surface Morphology and Structural Properties of β-FeSi₂ Films Manufactured Through Usage of Radio-Frequency Magnetron Sputtering.

In this research, β-FeSi₂ thin films were manufactured onto Si(111) wafer substrates through the usage of radio-frequency magnetron sputtering (RFMS) method at 2.66 × 10-1 Pa of sputtering pressure. The substrate temperatures were varied at 500 °C, 560 °C, and 600 °C. The Raman lines of the β-FeSi₂ fabricated at 500 °C revealed the peaks at the positions of ~174 cm-1, ~189 cm-1, ~199 cm-1, ~243 cm-1, ~278 cm-1, and ~334 cm-1. For the higher substrate temperatures of 560 °C and 600 °C, the Raman peaks of ~189 cm-1, ~243 cm-1, and ~278 cm-1 were shifted toward higher Raman positions. The surface view of the films was observed with several grains over the β-FeSi₂ film surface at all substrate temperatures. The average grain size of the films for the samples deposited at 500 °C and 560 °C was in the range of 28 to 30 nm, where the size was enlarged to 36 nm at 600 °C of substrate temperature. The root mean square roughness were 10.19 nm, 10.84 nm, and 13.67 nm for the β-FeSi₂ film surface prepared at the substrate temperatures of 500 °C, 560 °C, and 600 °C, respectively. The contact angle (CA) values were 99.25°, 99.80°, and 102.00° for the created samples at 500 °C, 560 °C, and 600 °C, respectively. As the acquired CA values, all β-FeSi₂ samples exhibited a hydrophobic property with CA in the range of 90° to 150°. Consequently, the produced β-FeSi₂ film surface employing the RFMS method indicated a potential to be employed in a hydrophobic coating application.

Kinetic Modelling of Molybdenum-blue Production by Bacillus sp. strain Neni-10

Kinetic modelling of bacterial reduction process reveals vital parameters like specific reduction rate, hypothetical maximum reduction and deduce whether high substrate (molybdenum) concentration affects the lag phase of the reduction. The commonly used natural logarithmic transformation to linearize the reduction process seems inaccurate as it gives only an approximate value for the specific growth rate. This work for the first time utilized eight different primary models such as Gompertz, Baranyi-Roberts, Logistic, Von Bertalanffy, Richards, Schnute, Buchanan three-phase Huang to obtain values of the kinetic constants that could further be used for secondary modelling. Baranyi-Roberts model was the best model fitting Mo-blue production curve in Bacillus sp. strain Neni-10 based on statistical values for RMSE (root-mean-square error), R2 (adjusted coefficient of determination), AICc (corrected Akaike Information Criterion) BF (bias factor) and AF (accuracy factor). The fitting parameters obtained were lag time (l), maximal Mo-blue production (Ymax) and maximum Mo-blue production rate (mm). The use of microbial growth models to get accurate Mo-blue production rate is entirely new to molybdenum reduction (detoxification) process and the kinetic constants obtained could be very useful secondary modelling. This work has revealed the usefulness of these models in modelling bacterial Mo-blue production

Residual Stress Measurement of Suspension HVOF-Sprayed Alumina Coating via a Hole-Drilling Method

The nature and magnitude of residual stresses in thermal-sprayed coatings determine their lifetime and failure mechanisms. The residual stresses of suspension high-velocity oxy-fuel (SHVOF) thermal sprayed alumina (Al2O3) coating were measured with hole-drilling and x-ray diffraction. The coating is dense and consists of amorphous and two crystalline phases: alpha and gamma. The residual stresses measured by hole-drilling in the Al2O3 coating was − 162 MPa (compression) in the longitudinal direction and − 104 MPa (compression) in the transverse direction. This is due to the peening stress and the high substrate–coating CTE ratio of ~ 2.1. The nature of the residual stress through the coating is related to the microstructure build-up shown from the cross section and the fracture surfaces of the coating.

The Influence of Magnetron Sputtering Conditions on the Structure of Zr–Pd Coatings

Using the method of DC magnetron sputtering, nonstructured amorphous metal coatings of Zr75Pd25 composition were obtained with an average deposition rate of 1.3 nm/s at a substrate temperature of 40°C, while crystalline coatings were formed at a higher substrate temperature. A crystalline coating with equilibrium phase composition was obtained at 350°C. Coatings deposited at intermediate temperatures contained predominantly a PdZr phase, in contrast to the equilibrium PdZr2 phase. The surface roughness of amorphous coatings was on a level of 0.2–0.5 nm, which was about ten times lower than the mean roughness of crystalline coatings with the same composition.

Palladium/nickel-mediated cross coupling reaction between phosphorylamides and alkenes toward enephosphorylamides

Enephosphorylamides were herein successfully prepared from phosphorylamides and substituted alkenes. The dehydrogenative transformation took place in the presence of a combination of a palladium diacetate and nickel dichloride. The transition metal-catalyzed methodology enjoyed high efficiency and broad substrate scope. Moreover, a plausible mechanism was proposed for the oxidative C–N cross coupling protocol.

Development of a highly sensitive microplate luminometer using ATP bioluminescence.

Analytical techniques using ATP bioluminescence, which has a high quantum yield and substrate specificity, are widely used in various assays, such as luciferase reporter assays, in the biological sciences. Although most microplate luminometers can be used to measure ATP luminescence with 96-well or 384-well microplates, their ATP detection limits are typically several tens of amol, which is not sufficient for evaluating cell activities and variability within small samples, such as those containing only a few cells. To analyze cell activities at low ATP concentrations, a more sensitive microplate luminometer is required. Therefore, in this study, we developed an automated highly sensitive microplate luminometer that could perform reagent dispensing and bioluminescence measurement with a 96-well microplate within 10 min. ATP bioluminescence was detected by pressing a photomultiplier tube (PMT) against a microplate surface to seal the measured well with the light-receiving surface of the PMT. This enabled a high light collection efficiency and low luminescence crosstalk, defined as the intensity of stray light from an adjacent well. As a result, the ATP detection limit was 0.97 amol, and the luminescence crosstalk was 4.4 × 10-6 . Both values were one order of magnitude better than that of a typical microplate luminometer. In addition, the same gradient linearity of luminescence intensity against the ATP concentration was confirmed for both high and low ATP concentrations, and the dynamic range of our microplate luminometer was 106 . Overall, our findings demonstrated that our novel microplate luminometer may have wide application in biological sciences research.

SURFACE MORPHOLOGY OF SPUTTERED TITANIUM-ALUMINUM-NITRIDE COATINGS

A study on the surface morphology of sputtered TiAlN coatings is presented. The coatings were deposited by DC magnetron sputtering on tungsten carbide insert tools. The surface morphology was characterized by using Atomic Force Microscopy (AFM), and the surface roughness was indicated by RMS roughness value. It was observed that the TiAlN coating surface morphology was rough as the negative substrate bias and nitrogen flow rate are increased. The evolution of the sputtered TiAlN coatings surface morphology was due to the competition between particle diffusion and re-scattering effect during the sputtering process. At high negative substrate bias and nitrogen flow rate, the re-scattering effect was prominent, leading to the high roughness of the sputtered TiAlN coating surface.

MEMS-Based Reflective Intensity-Modulated Fiber-Optic Sensor for Pressure Measurements.

A reflective intensity-modulated fiber-optic sensor based on microelectromechanical systems (MEMS) for pressure measurements is proposed and experimentally demonstrated. The sensor consists of two multimode optical fibers with a spherical end, a quartz tube with dual holes, a silicon sensitive diaphragm, and a high borosilicate glass substrate (HBGS). The integrated sensor has a high sensitivity due to the MEMS technique and the spherical end of the fiber. The results show that the sensor achieves a pressure sensitivity of approximately 0.139 mV/kPa. The temperature coefficient of the proposed sensor is about 0.87 mV/°C over the range of 20 °C to 150 °C. Furthermore, due to the intensity mechanism, the sensor has a relatively simple demodulation system and can respond to high-frequency pressure in real time. The dynamic response of the sensor was verified in a 1 kHz sinusoidal pressure environment at room temperature.

Fungi decontamination by gaseous ozone of fresh, dried and salted mackerel (Acanthocybium solandri)

The aim of this study was to investigate the antifungal effect of ozone gas (O3) (green decontamination agent) on mackerel fish (Acanthocybium solandri) in different types of preservation (fresh, dry and salted). Samples humidity [mc / aw] parameters prior gas treatment, were of 80.7%/0.98, 55.55%/0.74 and 49.5%/0.70, respectively. Fish were contaminated with fungi genera that are able to grow on high (Fusarium) and low (Aspergillus / Penicilliun) moisture content substrates, then gas treated at 50 μmol O3 /mol, exposed during 10, 20 and 30 min, and incubated (25ºC, 7 days) to evaluate fungal inactivation. The O3 treated samples, when O3 exposed during the longest time (30 min/Day 7th) had the fungal growth totally inhibited (100%), while the others presented only reduced growth effect, i.e; 40 and 70 % for 10 and 20 min, respectively. Fusarium spores were not able to grow in any of the protein based sample studied (both, Control & Treated Group). On the other hand, Aspergillus and Penicilliun although grew on Control and some treated ones, their growth was inhibited by O3 depending on exposure time. That gas showed (under the conditions applied) to be fungi control effective for mackerel different forms of conservation.

Developing a Modified Umbrella Index for Conservation of Macroinvertebrate Diversity in Taizi River Basin, China

Conservation strategies for a reliable set of umbrella species should benefit many co-occurring species and will improve conservation efficiency. The umbrella index (UI) is increasingly applied for umbrella species selection in different ecosystems. We developed a modified river UI to select potential macroinvertebrate umbrella species with a combination of 69 sites in the Taizi River Basin of northeast China. Calculation of UI and comparison of biotic indices between sites of presence and absence of umbrella species were performed to make the final umbrella species list. The umbrella scheme, based on the proportion and composition of sites supporting the confirmed umbrella species, was introduced to illustrate the conservation effectiveness. A total of eight umbrella species were obtained and all of them were aquatic insects, such as caddisfly and mayfly larva. Umbrella schemes supporting the top umbrella species, hosted the majority of co-occurring species and only 7% of beneficiary species were missed by the umbrella schemes of 70% effort. The positive relationship between abundance of co-occurring species and umbrella species, validated the ability of umbrella species to confer protection and co-existence of co-occurring species, and thus indicated the effectiveness of umbrella species conservation. Co-occurring species were located close to umbrella species in ordinations, suggesting they respond to similar environmental variables characterized by high flow velocity, dissolved oxygen and pebble-covered substrate. On account of good performance of umbrella schemes in our study, UI with further improving methods should be promoted for selection of umbrella species and decision for optimizing of conservation sites in the future.

Taxonomic and functional diversity of mollusk assemblages in a tropical rocky intertidal zone

ABSTRACT We investigated the spatial variation of molluscan assemblages with different habitat-forming species and bare rock habitat in a rocky intertidal zone in northeastern Brazil. The high intertidal zone substrate was covered predominantly of barnacles [Chthamalus bisinuatus (Pilsbry, 1916)], the mid-intertidal of mussels [Brachidontes exustus (Linnaeus, 1758)] and the low intertidal of macroalgae chlorophytes [Gayralia oxysperma (Kützing) K. L. Vinogradova ex Scagel et al., 1989 and Ulva lactuca Linnaeus, 1753], phaeophytes [Sargassum vulgare C. Agardh] and rhodophytes [Palisada flagellifera (J.Agardh) K. W. Nam, 2007]. A total of 3,861 mollusks were recorded, belonging to the classes Gastropoda (9 species; 3,800 individuals), Bivalvia (3 spp.; 54 ind.), and Polyplacophora (1 sp.; 7 ind.). Functional diversity was accessed through the trophic structure, in which we identified food guilds: suspension feeders, grazers, herbivores, and carnivores. The analysis revealed significant differences in mollusk abundance, species richness, diversity indices, and trophic diversity among barnacle belts, mussel beds, algae habitat, and bare rock habitats. The highest species richness and trophic diversity were detected in algae habitat and mussel beds, which showed low abundance. In contrast, barnacle belts registered low species richness and trophic diversity and a high number of individuals. Bare rock recorded low values in all surveyed indices. This result points to the effect of environmental modification caused by habitat-forming species in this system. These species increase environmental complexity and enable the establishment of organisms through facilitation processes. The various food guilds found in this study reaffirm the role of habitat-forming species in providing niches that support different occupation patterns.

An Analytical Scalable Lumped-Element Model for GaN on Si Inductors

In this paper, a wide-band distributed model that can approximate the behaviour of square and octagonal inductors, both with and without tapering, is presented. This paper also presents a novel way of accurately modelling the lateral coupling in the substrate. The presented model can be applied to any foundry process, and its validity has been demonstrated using a novel technology, the D01GH GaN process developed by OMMIC, which has a high resistivity substrate. To do so, seventeen inductors have been designed and manufactured. The proposed model has been verified against EM simulations and measurements of the designed inductors. Comparisons show that the model can correctly estimate the behaviour of the inductor, improving the results of the EM simulations for most cases. The root mean square (RMS) error calculated across the samples when estimating the inductance is 0.0565. The RMS error for the quality factor results (2.2727) is also adequate, although there is more deviation when comparing the results with the measurements.