2D space–time wave-digital multi-fan filter banks for signals consisting of multiple plane waves

Two dimensional space–time fan filters may be used for the highly-selective enhancement of spatio-temporal plane-waves on the basis of their directions of arrival. Unlike uniform bandwidth beam filters, ideal fan filters transmit passband signals over a range of directions of arrival that is independent of their 1D temporal spectrum. In this work, closed-form 2D wave-digital filter design equations and corresponding hardware architectures are proposed for realizing M independent fan-shaped passbands having independently steerable directionality and selectivity. A design method based on LCR ladder networks is proposed and implemented using a 2D time-multiplexed raster-scanned architecture that is suitable for low frequency applications such as audio, multimedia, seismic and ultrasonic beamforming. The architectures are designed, simulated, physically realized and tested on FPGA-based prototypes. Examples of 2D IIR M-fan filterbanks with FPGA implementations, together with measured results from on-chip hardware verifications, show the successful design and hardware realization. The filterbanks and hardware architectures are shown to be suitable for real-time sensor-array beamforming applications using custom VLSI circuits.     

Sensitive pH detection on gold interdigitated electrodes as an electrochemical sensor

Microsystem Technologies - Miniaturized in-house high-performance sensors are mandatory for implementing the current needs efficiently. With the microsystems, electrode material is crucial to...     

Antimicrobial and Anti-Biofilm Peptide Octominin for Controlling Multidrug-Resistant Acinetobacter baumannii

Acinetobacter baumannii is a serious nosocomial pathogen with multiple drug resistance (MDR), the control of which has become challenging due to the currently used antibiotics. Our main objective in this study is to determine the antibacterial and antibiofilm activities of the antimicrobial peptide, Octominin, against MDR A. baumannii and derive its possible modes of actions. Octominin showed significant bactericidal effects at a low minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of 5 and 10 µg/mL, respectively. Time-kill kinetic analysis and bacterial viability tests revealed that Octominin showed a concentration-dependent antibacterial activity. Field-emission scanning electron microscopy (FE-SEM) analysis revealed that Octominin treatment altered the morphology and membrane structure of A. baumannii. Propidium iodide (PI) and reactive oxygen species (ROS) generation assays showed that Octominin increased the membrane permeability and ROS generation in A. baumannii, thereby causing bacterial cell death. Further, a lipopolysaccharides (LPS) binding assay showed an Octominin concentration-dependent LPS neutralization ability. Biofilm formation inhibition and eradication assays further revealed that Octominin inhibited biofilm formation and showed a high biofilm eradication activity against A. baumannii. Furthermore, up to a concentration of 100 µg/mL, Octominin caused no hemolysis and cell viability changes in mammalian cells. An in vivo study in zebrafish showed that the Octominin-treated group had a significantly higher relative percentage survival (54.1%) than the untreated group (16.6%). Additionally, a reduced bacterial load and fewer alterations in histological analysis confirmed the successful control of A. baumannii by Octominin in vivo. Collectively, these data suggest that Octominin exhibits significant antibacterial and antibiofilm activities against the multidrug-resistant A. baumannii, and this AMP can be developed further as a potent AMP for the control of antibiotic resistance.     

A real-time quantitative assessment of self-assembled quantum dots by reflection high-energy electron diffraction

A method for in-situ quantitative characterization of quantum dots during growth is provided using the readily available reflection high-energy electron diffraction (RHEED). RHEED patterns of uncapped self-assembled InAs/GaAs quantum dots are investigated theoretically and experimentally. Previously predicted intensity fringes along chevron tails of quantum dot's RHEED diffraction spots are observed experimentally. Post-growth atomic force microscopic images and theoretical RHEED images of the same are obtained parallel to experimental data. The bounding facets of the quantum dots are determined using the angle between the chevrons. The size (height) of the quantum dots is determined using the periodicity of intensity fringes along the chevrons during growth.     

pH‐Sensitive Polymeric Nanoparticles Modulate Autophagic Effect via Lysosome Impairment

In drug delivery systems, pH‐sensitive polymers are commonly used as drug carriers, and significant efforts have been devoted to the aspects of controlled delivery and release of drugs. However, few studies address the possible autophagic effects on cells. Here, for the first time, using a fluorescent autophagy‐reporting cell line, this study evaluates the autophagy‐induced capabilities of four types of pH‐sensitive polymeric nanoparticles (NPs) with different physical properties, including size, surface modification, and pH‐sensitivity. Based on experimental results, this study concludes that pH‐sensitivity is one of the most important factors in autophagy induction. In addition, this study finds that variation of concentration of NPs could cause different autophagic effect, i.e., low concentration of NPs induces autophagy in an mTOR‐dependent manner, but high dose of NPs leads to autophagic cell death. Identification of this tunable autophagic effect offers a novel strategy for enhancing therapeutic effect in cancer therapy through modulation of autophagy.     

Assays of endogenous caspase activities: a comparison of mass spectrometry and fluorescence formats

This paper describes a label-free assay for measuring endogenous caspase protease activities in cell lysates. The assay format, termed SAMDI-MS (self-assembled monolayers for matrix assisted laser desorption ionization time-of-flight mass spectrometry), is based on the enzymatic modification of peptides immobilized to monolayer substrates, followed by direct detection of the products with mass spectrometry. Monolayers presenting peptide substrates for either caspase-3 or -8 were treated with lysates from Jurkat cells that were stimulated with staurosporine and SKW6.4 cells that were stimulated with LzCD95L. In both cases, the SAMDI assays reported on the activation of endogenous caspase enzymes with levels of detection that are similar to those observed using the commonly employed fluorogenic assays. The use of longer peptide substrates, which are not compatible with the fluorogenic assays, provided for a better resolution of the two caspase activities. This work is significant because it demonstrates that the SAMDI assay can be used to measure endogenous enzyme activities and because it avoids the loss of activity and specificity that often accompany label-dependent assay formats.     

How do cattle respond to sloped floors? An investigation using behavior and electromyograms

On dairy farms, flooring is often sloped to facilitate drainage. Sloped floors have been identified as a possible risk factor for lameness, but relatively little is known about how this flooring feature affects dairy cattle. Ours is the first study to evaluate the short-term effects of floor slope on skeletal muscle activity, restless behavior (measured by number of steps), and latency to lie down after 90 min of standing. Sixteen Holstein cows were exposed to floors with a 0, 3, 6, or 9% slope in a crossover design, with a minimum of 45 h between each testing session. Electromyograms were used to evaluate the activity of middle gluteal and biceps femoris muscles. Muscle activity was evaluated in 2 contexts: (1) static muscle contractions when cows continuously transferred weight to each hind leg, before and after 90 min of standing; and (2) dynamic contractions that occurred during 90 min of treatment exposure. Median power frequency and median amplitude of both static and dynamic muscle electrical signals were calculated. Total muscle activity was calculated using the root mean square of the signals. Restless behavior, the number of steps per treatment, steps and kicks in the milking parlor, and the latency to lie down after the test sessions were also measured. It was predicted that restless behavior, muscle fatigue (as measured by median power frequency and median amplitude), total muscle activity, and latency to lie down after testing would increase with floor slope. However, no treatment differences were found. Median power frequency was significantly greater for the middle gluteal muscle [35 ± 4 Hz (mean and SE)] compared with the biceps femoris muscle (24 ± 3 Hz), indicating that the contractive properties of these muscles differ. The number of steps per minute and total muscle activity increased significantly over 90 min of standing, irrespective of floor slope. Although restless behavior and muscle function did not change with slope in our study, this work demonstrates that electromyograms can be used to measure skeletal leg muscle activity in cattle. This technology, along with restless behavior, could be useful in assessing cow comfort in other situations, such as prolonged standing.     

Stepping behavior and muscle activity of dairy cattle standing on concrete or rubber flooring for 1 or 3 hours

The type of flooring in dairy cattle systems influences cows' health and welfare. Although concrete is common, the use of more compressible flooring, such as rubber, is increasing. Cows prefer to stand and walk on rubber surfaces than on concrete; however, it is largely unknown how walking and standing for longer periods of time influence muscle activity and fatigue. Therefore, we used measures of behavior and muscle activity to investigate the potential benefits of providing a rubber flooring surface to dairy cattle. Sixteen lactating Holstein cows were forced to stand on either concrete or rubber flooring for 1 or 3 h in a 2 × 2 crossover design. Surface electromyograms (SEMG) and skin surface temperature were used to evaluate muscle activity, fatigue, and movement of muscle activity between the hind legs. Activity of 2 muscles, the bicep femoris and middle gluteal, was assessed during both static contractions, when cows transferred weight to each hind leg, before and after 1 and 3 h of standing, and dynamic contractions, associated with steps and with shifts in weight without steps. In addition, we evaluated stepping rate, time between each step, feeding behavior, skin surface temperature, and latency to lie down after standing. Standing duration influenced both the behavior and muscle activity of cows. Stepping rate increased with standing time for cows on both flooring types. Static muscle activity parameters of the bicep femoris muscle were higher after 3 h of standing for cows standing on both flooring types (2.3 and 3.6% increases in median amplitude and median power frequency, respectively) compared with the change after 1 h and compared with baseline values before the standing treatment. Flooring type influenced the behavior and muscle activity of the cows, particularly during the first hour of exposure; cows standing on rubber had a higher stepping rate, shorter interval between steps, and higher number of SEMG shifts (muscle activity shifts with or without visible steps) than cows on concrete. There was no difference in skin surface temperature, feeding behavior, or latency to lie down between the treatments. The results show that standing on a rubber flooring caused a different initial behavioral response compared with standing on concrete; however, possible reasons for these changes are unclear. Standing for 3 h resulted in an increase in stepping rate and in some muscle activity parameters; however, the results regarding muscle fatigue in relation to flooring type are inconclusive.