Experimental and theoretical investigation of sensing parameters in carbon nanotube‐based DNA sensor

Nowadays, sensitive biosensors with high selectivity, lower costs and short response time are required for detection of DNA. The most preferred materials in DNA sensor designing are nanomaterials such as carbon and Au nanoparticles, because of their very high surface area and biocompatibility which lead to performance and sensitivity improvements in DNA sensors. Carbon nanomaterials such as carbon nanotubes (CNTs) can be considered as a suitable DNA sensor platform due to their high surface‐to‐volume ratio, favourable electronic properties and fast electron transfer rate. Therefore, in this study, the CNTs which are synthesised by pulsed AC arc discharge method on a high‐density polyethylene substrate are used as conducting channels in a chemiresistor for the electrochemical detection of double stranded DNA. Moreover, the response of the proposed sensor is investigated experimentally and analytically in different temperatures, which confirm good agreement between the presented model and experimental data.Inspec keywords: electrochemical sensors, polymers, arcs (electric), biological techniques, nanosensors, carbon nanotubes, DNAOther keywords: C, chemiresistor, double stranded DNA detection, CNT, electronic properties, surface‐to‐volume ratio, nanoparticles, biosensors, electrochemical detection, high‐density polyethylene substrate, pulsed AC arc discharge method, electron transfer rate, carbon nanomaterials, carbon nanotube‐based DNA sensor     

Scattering by layered structures with rough surfaces: comparison of polarimetric optical scatterometer measurements with theory

A laboratory model of a layered structure with a rough upper surface (a glass microscope slide cut with a diamond saw) is used to obtain optical polarimetric data. Scatterometer measurements were made of all the Mueller matrix elements associated with light scattered in arbitrary directions. (A preliminary measurement of scattering from a smooth opaque gold film on a silicon wafer was used to validate the calculation of the Mueller matrix elements.) These measurements are compared with corresponding analytical solutions based on the full-wave approach. Physical interpretations of the analytical solutions that account for scattering upon reflection and transmission across rough interfaces are given in a companion paper. The agreement between calculations and measurements suggests that the full wave, polarimetric solutions can provide a reliable database for electromagnetic detection of rough surfaces in remote-sensing applications.     

Microfluidic biochemical sensor based on circular SIW‐DMS approach for dielectric characterization application

This work proposes an advancement of microwave planar resonator sensor with high sensitivity for microfluidic dielectric characterization. The physical design was employed based on circular substrate integrated waveguide (CSIW) with an integration of defected microstrip structure (DMS). This approach can be applied to accelerate the dielectric detection, structure miniaturization and material differentiation. The presented sensor operates based on variations in the dielectric properties of solvents in the vicinity of a planar open‐ended microstrip resonator device. Further analysis in volume and concentration were performed to validate the reliability of the sensor. Validation and functionality of the sensor were investigated by experimental and results comparison. A mathematical model was developed to determine the dielectric constant and the loss tangent of the microfluidic samples. The average error detection has a lower percentage value of 0.11% by comparison to the commercial and ideal dielectric properties of the aqueous samples. The maximum relative error detection, ±0.37% implied better accuracy compared to the existing resonator sensors with more than 400 of the Q‐factor. The proposed CSIW‐DMS sensor was found to give higher accuracy and detection response; besides easier to fabricate, and compatible for integration with other electronic components in an RF sensor for variety of applications.     

Hardware Transactional Memory Exploration in Coherence-Free Many-Core Architectures

High-end embedded systems, like their general-purpose counterparts, are turning to many-core cluster-based shared-memory architectures that provide a shared memory abstraction subject to non-uniform memory access costs. In order to keep the cores and memory hierarchy simple, many-core embedded systems tend to employ simple, scratchpad-like memories, rather than hardware managed caches that require some form of cache coherence management. These “coherence-free” systems still require some means to synchronize memory accesses and guarantee memory consistency. Conventional lock-based approaches may be employed to accomplish the synchronization, but may lead to both usability and performance issues. Instead, speculative synchronization, such as hardware transactional memory, may be a more attractive approach. However, hardware speculative techniques traditionally rely on the underlying cache-coherence protocol to synchronize memory accesses among the cores. The lack of a cache-coherence protocol adds new challenges in the design of hardware speculative support. In this article, we present a new scheme for hardware transactional memory (HTM) support within a cluster-based, many-core embedded system that lacks an underlying cache-coherence protocol. We propose two alternative data versioning implementations for the HTM support, Full-Mirroring and Distributed Logging and we conduct a performance comparison between them. To the best of our knowledge, these are the first designs for speculative synchronization for this type of architecture. Through a set of benchmark experiments using our simulation platform, we show that our designs can achieve significant performance improvements over traditional lock-based schemes.     

Aqueous-phase reforming of biomass using various types of supported precious metal and raney-nickel catalysts for hydrogen production

Aqueous-phase reforming (APR) of real biomass was studied for production of hydrogen gas. Wheat straw, an abundant by-product from wheat production was used as representative lignocellulosic biomass. Wheat straw was hydrolyzed in an environmentally benign-sub critical water condition. APR experiments of wheat straw hydrolysates were performed using commercial catalysts which were made of Pt, Pd and Ru doped on carbon, activated carbon and alumina supports for production of hydrogen rich gas mixture. The activity and selectivity of two commercial raney-nickel catalysts were also monitored in terms of hydrogen production.     

Lensfree sensing on a microfluidic chip using plasmonic nanoapertures

We demonstrate lensfree on-chip sensing within a microfluidic channel using plasmonic nanoapertures that are illuminated by a partially coherent quasimonochromatic source. In this approach, lensfree diffraction patterns of metallic nanoapertures located at the bottom of a microfluidic channel are recorded using an optoelectronic sensor-array. These lensfree diffraction patterns can then be rapidly processed, using phase recovery techniques, to back propagate the optical fields to an arbitrary depth, creating digitally focused complex transmission patterns. Cross correlation of these patterns enables lensfree on-chip sensing of the local refractive index surrounding the near-field of the plasmonic nanoapertures. Based on this principle, we experimentally demonstrate lensfree sensing of refractive index changes as small as ～2×10(-3). This on-chip sensing approach could be quite useful for development of label-free microarray technologies by multiplexing thousands of plasmonic structures on the same microfluidic chip, which can significantly increase the throughput of sensing.     

Assessment of correlated dose and sensitivity profiles on a multi-slice CT scanner

In the case of computed tomography (CT) scanners as well as other imaging techniques utilising ionising radiation, it is imperative that radiation is confined to the sensitive part of the image detector. Assuring this for a CT scanner requires detailed information about the scanner dose and sensitivity profiles and their spatial correlation. The profiles should ideally be co-centric and tightly fit to each other. Ensuring this inherent performance of the scanner can be seen as one of the fundamental steps in optimising diagnostic examinations with CT. A measurement device using a dedicated liquid ionisation chamber is employed to investigate the performance of a Toshiba Aquilion 16 scanner in this aspect. Dose profile and sensitivity profile pairs for four collimations are presented where each pair of profiles are spatially correlated to each other. The measurement device can be applied to any scanner for fast and accurate assessment of dose and sensitivity profiles and their spatial correlation.     

Changes in the quality of fishburger produced from Tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>) during frozen storage (−18 °C)

In this study, the chemical and sensory qualities of fishburger produced from tilapia (Oreochromis niloticus) were investigated during frozen storage (–18 °C) over 8 months. The ratios of crude protein, lipid, moisture, crude ash, and polyunsaturated fatty acids in tilapiaburger were found to be 17.82%, 5.29%, 66.68%, 2.56% and 7.95% respectively. At the end of the study, the total volatile basic nitrogen value was found to have fluctuated throughout the storage periods. The highest thiobarbituric acid value was found at the 7th month as 0.142 mg malonaldehyde/kg. The peroxide value was 0.18 meq/kg at the beginning of the storage but increased to 5.03 meq/kg at 6th month of storage and then decreased to 0.82 meq/kg at the 8th month. The level of free fatty acids was 2.73% oleic acid at the beginning but reached 4.14% in the first month of storage and then increased to 5.92% at the end of the storage. pH values ranged between 8.01 and 7.97. At the end of the storage period, sensory quality criteria were scored as quite near those of the fresh samples.     

RNA bulge entropies in the unbound state correlate with peptide binding strengths for HIV-1 and BIV TAR RNA because of improved conformational access

For the binding of peptides to wild-type HIV-1 and BIV TAR RNA and to mutants with bulges of various sizes, changes in the DeltaDelta G values of binding were determined from experimental K d values. The corresponding entropies of these bulges are estimated by enumerating all possible RNA bulge conformations on a lattice and then applying the Boltzmann relationship. Independent calculations of entropies from fluctuations are also carried out using the Gaussian network model (GNM) recently introduced for analyzing folded structures. Strong correlations are seen between the changes in free energy determined for binding and the two different unbound entropy calculations. The fact that the calculated entropy increase with larger bulge size is correlated with the enhanced experimental binding free energy is unusual. This system exhibits a dependence on the entropy of the unbound form that is opposite to usual binding models. Instead of a large initial entropy being unfavorable since it would be reduced upon binding, here the larger entropies actually favor binding. Several interpretations are possible: (i) the higher conformational freedom implies a higher competence for binding with a minimal strain, by suitable selection amongst the set of already accessible conformations; (ii) larger bulge entropies enhance the probability of the specific favorable conformation of the bound state; (iii) the increased freedom of the larger bulges contri-butes more to the bound state than to the unbound state; (iv) indirectly the large entropy of the bound state might have an unfavorable effect on the solvent structure. Nonetheless, this unusual effect is interesting.     

Remote sensing of layered media with non-Gaussian random roughinterfaces full-wave approach

A full-wave approach is used to investigate electromagnetic scattering from three-media irregular-layered structures. The surface height of the rough interface is characterized by a family of gamma probability density functions (pdfs) of order K. For random rough surface heights characterized by one-sided pdfs, the thickness of the coating material can be chosen to be positive everywhere. When the rough surface heights are characterized by the familiar (two-sided) Gaussian pdf, convergence problems arise since a finite probability exists that the thickness of the coating is “negative”