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We report on the design and fabrication of a hybrid sensor that integrates transmission-mode localized surface plasmonic resonance (LSPR) into a quartz crystal microbalance (QCM) for studying biochemical surface reactions. The coupling of LSPR nanostructures and a QCM allows optical spectra and QCM resonant frequency shifts to be recorded simultaneously and analyzed in real time for a given surface adsorption process. This integration simplifies the conventional combination of SPR and QCM and has the potential to be miniaturized for application in point-of-care (POC) diagnostics. The influence of antibody-antigen recognition effect on both the QCM and LSPR has been analyzed and discussed. [ABSTRACT FROM AUTHOR]

Abstract: Research in to label free methods for biological analysis have brought interesting developments. Cell impedance spectroscopy has been one of the promising outcomes. Here we show the development of an 8-well impedance measurement setup and studied the use of conducting polymers as electrode material in cell impedance spectroscopy. We have developed devices using PEDOT:PSS electrodes and shown its advantages (lower impedance and faster to reach electrochemical equilibrium) over conventional materials, such as gold. It is observed through electrochemical analysis that the lower interfacial impedance is due to the low charge transfer resistance of PEDOT:PSS. MDCK cell proliferation experiments were performed using both types of electrode materials to provide a comparative result. We applied electrical modeling methods to understand the cell–substrate interactions and shown its applications in cell impedance spectroscopy. This study presents the development and advantages of cell impedance spectroscopy using conducting polymer electrodes. [Copyright &y& Elsevier]

Abstract: Beam-steering techniques are required to fully exploit the benefits of present and future terahertz imaging systems. We propose and model a device that overcomes the difficulties that prevent analogues of existing electrical and optical micro-mechanical techniques being employed at terahertz frequencies. The device employs a variable phase-control medium comprised of interlocking artificial dielectric surfaces. We present an analytical array factor calculation that provides insight into the operation of the device and an improved discrete array factor model incorporating the complex transmission coefficients of the structure. The models are validated by comparison to results from a rigorous full-vector electromagnetic solver tool (finite-difference time-domain). We predict a practical device constructed from a silicon substrate could steer both TE and TM beams by up to 6.4°. [Copyright &y& Elsevier]

Underway replenishment is an essential component of long-term naval operations. During underway replenishment, two ships travel in close proximity at moderate forward speed. This paper examines the hydrodynamic interactions that can influence seakeeping during such operations. Presented numerical predictions include the influence of interaction effects on hydrodynamic forces for two ships in waves. A scarcity of validation material for numerical predictions prompted new towing tank experiments for two ships in waves. The experiments used semi-captive models, and the numerical code was modified to include restraining forces for specified modes. The numerical predictions and experiments show that the presence of a larger ship can significantly influence the motions of a smaller ship in close proximity. [Copyright &y& Elsevier]

Hunting lions while their populations are declining in much of Africa is a highly controversial issue. However, hunting for lions and other charismatic large mammals in Africa has contributed to maintaining large areas of wild land for lions and wildlife conservation. To minimise the impacts of hunting lions in some 150,000 km2 of Game Management Areas (total ∼190,000 km2) in Zambia an age-based quota setting system has been adopted. The approach involves reducing the number of lions taken to one per hunting block and limiting trophy hunting to past prime male lions. The age-based assessment criteria and the results from assessing the trophies taken in 2017 and 2018 are presented. Of the 18 trophies taken in 2017, 11% were judged to be under age, 17% were marginal and the remaining 72% were acceptable trophies of animals aged 6 years or older, with 28% being ≥7 years or older. The results for 2018 showed a higher proportion (42%) of older lions (≥7 years) being taken. Legal instruments to give force to the guidelines on trophies that can legally be hunted are being introduced to ensure the sustainable offtake of past prime male lions with minimal disruption of pride coalitions. These developments will contribute to improved management of lion hunting in Zambia and to meeting the non-detriment finding and conservation enhancement requirements of European and American regulations governing the importation of lion trophies. [ABSTRACT FROM AUTHOR]

We have demonstrated a chip-based diagnostics tool for the quantification of metabolites, using specific enzymes, to study enzyme kinetics and calculate the Michaelis-Menten constant. An array of 256×256 ion-sensitive field effect transistors (ISFETs) fabricated in a complementary metal oxide semiconductor (CMOS) process is used for this prototype. We have used hexokinase enzyme reaction on the ISFET CMOS chip with glucose concentration in the physiological range of 0.05 mM – 231 mM and successfully studied the enzyme kinetics of hexokinase in detail. This will promote future research towards multiplexing enzyme-based metabolite quantification on a single chip, ultimately opening a pathway towards a personal metabolome machine. [ABSTRACT FROM AUTHOR]

Lack of commitment to infertility investigations and treatment was not the reason for patient dropout. [Copyright &y& Elsevier]

Failure to adhere to therapy is common in couples with fertility problems. Explaining why is difficult and worthy of further investigation without stigmatizing assumptions. [Copyright &y& Elsevier]

Abstract: We describe a complete lab-on-a-chip type ion-sensitive chemical sensor array system for imaging proton concentration and flow. The core of the imaging system relies on a 715.8μm×715.8μm large 64×64-pixel ISFET sensor array that is designed and fabricated in a conventional 4-metal 0.35μm CMOS process along with readout circuitry and additional electronics. The high-speed and real-time data acquisition of ∼100frame per second (fps), 40μs per pixel, results in a large amount of data that is streamed to the hard disk. Image reconstruction methods allow visualization of the dynamic behavior of chemical substances and ionic spreads over the sensor array at a resolution of the size of a pixel. The functionalities of the on-chip ion-camera device are demonstrated using appropriate acid and alkaline solutions. A pH sensitivity of 20mV/pH was achieved without modification to the foundry processed chip. [Copyright &y& Elsevier]

This work presents two different approaches for the implementation of pseudomorphic high electron mobility transistors (pHEMTs) and planar Gunn diodes on the same gallium arsenide substrate. In the first approach, a combined wafer is used where a buffer layer separates the active layers of the two devices. A second approach was also examined using a single wafer where the AlGaAs/InGaAs/GaAs heterostructures were designed for the realisation of pHEMTs. The comparison between the two techniques showed that the devices fabricated on the single pHEMT wafer presented superior performance over the combined wafer technique. The DC and small-signal characteristics of the pHEMTs on the single wafer were enhanced after the use of T-gates with 70 nm length. The maximum transconductance of the transistors was equal to 780 mS/mm with 200 GHz maximum frequency of oscillation ( f max ). Planar Gunn diodes fabricated in the pHEMT wafer, with 1.3 μm anode-to-cathode separation ( L AC ) presented oscillations at 87.6 GHz with maximum power of oscillation equal to −40 dBm. [ABSTRACT FROM AUTHOR]

Abstract: Variations in tissue autofluorescence (AF) can be exploited to detect early signs of intestinal cancer, however current endoscopic AF systems are only able to inspect the oesophegus and large intestine. We present the design, fabrication and testing of a pill capable of inducing and detecting AF from mammalian intestinal tissue. The prototype comprises an application specific integrated circuit (ASIC), illumination LED, optical filters to minimise sensor response to crosstalk from the illumination wavelength, a pulse counter/control unit and a radio transmitter. The ASIC implements a single photon avalanche diode detector (SPAD), and integrated high voltage (up to 37.9V) charge pump power supply. The SPAD is biased above its breakdown voltage to operate in Geiger mode, and exhibits a detection efficiency peak at 465nm, sufficiently close to human tissue autofluorescence's peak of 520±10nm. The ASIC was fabricated using a commercial high-voltage CMOS process. The complete device uses an average power of only 21.4mW. The implemented system has been characterised against controlled solutions of fluorophores and tested in vitro with biological samples. It has been proven to be capable of inducing and detecting fluorescence in fluorophore solution concentration as low as 1nM, and with mammalian intestinal tissue. [Copyright &y& Elsevier]

Abstract: We present detailed design, fabrication and characterization of In0.23Ga0.77As-based planar Gunn diodes in this paper. The devices have AlGaAs/InGaAs/AlGaAs heterojunctions that were grown on a semi-insulating GaAs wafer using molecular beam epitaxy technology. Electron beam lithography was used to define anode and cathode terminal patterns. Devices with various anode–cathode separations (e.g. 4–1.4μm) were fabricated on the same chip. Spectrum measurements showed oscillation frequencies between 36GHz and 118GHz in the fundamental transit-time mode of operation. These devices show great potential as millimeter wave and sub-millimeter wave signal sources for their small size, MMIC compatibility and lithographically controlled oscillation frequencies. [Copyright &y& Elsevier]

Abstract: African elephants can affect the quality of the habitat of other species by breaking or uprooting trees and shrubs in savannas. Their effect on vegetation has been widely studied but less is known about the effects of such vegetation changes on other animals. We studied how changes in the vegetation caused by elephants influence the selection of microhabitats by five African herbivore species (giraffe, kudu, steenbok, impala, and zebra) in Hwange National Park, Zimbabwe. There was no clear significant effect of overall elephant-induced vegetation changes on microhabitat selection except for the small species (steenbok and impala) that used vegetation modified by elephants preferentially. This is consistent with a medium-term browsing facilitation hypothesis. More subtle possible effects were detected for larger browsers (giraffe and kudu). They selected areas with broken and uprooted plants and avoided coppiced areas. All of the browsers selected sites characterized by plants uprooted and broken by elephants, which were associated with a higher visibility, and ultimately a better probability of detecting an approaching predator, suggesting that perceived predation risk plays an important role in microhabitat selection. These results illustrate how elephants can initiate indirect effects that influence microhabitat selection by other herbivores. Understanding the indirect effects of elephants through changes in food availability and predation risk thus needs further investigation. The results of this study do not provide support for the hypothesis that elephant-induced changes in the structure of habitats have caused the declines in the populations of the other herbivores in the study area. [Copyright &y& Elsevier]

• A sensor array performs better than a standalone sensor with the same area independently by the type of the sensor. • A defined signal standard deviation can be achieved by tuning the number of sensors embedded into a sensor array. • Optimization strategy for simultaneous multiple sensing on a sensor array. An important consideration when scaling semiconductor sensor devices is the effect it may have on noise performance. Overall signal to noise ratio can be improved both by increasing sensor size, or alternatively by averaging the signal from two or more smaller sensors. In the design of sensor systems it is not immediately clear which is the best strategy to pursue. In this paper, we present a detailed theoretical and experimental study based on three different sensor arrays that show that an array of small independent sensors is always less noisy than a large sensor of the same size. [ABSTRACT FROM AUTHOR]