Hybrid Zinc Oxide Nanorods/Carbon Nanotubes Composite for Nitrogen Dioxide Gas Sensing

This study reports on the synthesis and fabrication of hybrid nanocomposite based on single-walled carbon nanotubes–ZnO nanorods (SWCNT-ZnONR) as resistive gas sensors for NO₂ detection. The sensor was prepared using the standard simple and cost-effective hydrothermal process. The sensor was characterized by x-ray diffraction (XRD) and scanning electron microscopy. The findings revealed enhanced porous SWCNT-ZnONR nanocomposites due to the high porosity of the SWCNT. It was also found that the sensor exhibited average response and recovery times of about 70 s and 100 s, respectively. The XRD peak at 26° indicated that the SWCNT pattern was not disturbed, while sensitivity increased with temperature up to 150°C, at which the sensitivity was maximum. Similarly, the sensor sensitivity increased with NO₂ concentration at all levels examined. Moreover, the results indicate that the sensor shows significant promise for NO₂ gas sensing applications.     

Influence of capsule shell composition on the performance indicators of hypromellose capsule in comparison to hard gelatin capsules

The purpose of this study was to assess the in vitro performances of “vegetable” capsules in comparison to hard gelatin capsules in terms of shell weight variation, reaction to different humidity conditions, resistance to stress in the absence of moisture, powder leakage, disintegration and dissolution. Two types of capsules made of HPMC produced with (Capsule 2) or without (Capsule 3) a gelling agent and hard gelatin capsules (Capsule 1) were assessed. Shell weight variability was relatively low for all tested capsules shells. Although Capsule 1 had the highest moisture content under different humidity conditions, all capsule types were unable to protect the encapsulated hygroscopic polyvinylpyrrolidone (PVP) powder from surrounding humidity. The initial disintegration for all Capsule 1 occurred within 3?min, but for other types of capsules within 6?min (n?=?18). Dissolution of acetaminophen was better when the deionized water (DIW) temperature increased from 32 to 42?°C in case of Capsule 1, but the effect of temperature was not significant for the other types of capsules. Acetaminphen dissolution from Capsule 1 was the fastest (i.e. >90% in 10?min) and independent of the media pH or contents unlike Capsule 2 which was influenced by the pH and dissolution medium contents. It is feasible to use hypromellose capsules shells with or without gelling agent for new lines of pharmaceutical products, however, there is a window for capsule shells manufacturing companies to improve the dissolution of their hypromellose capsules to match the conventional gelatin capsule shells and eventually replace them.     

Sequential circuit design for networks of threshold functions in nanotechnology

Microsystem Technologies - While a general strategy for designing combinational circuits exists, little work has been done on sequential circuits using nanotechnology. This is due to the logic used...     

Hybrid Feature Extractions and CNN for Enhanced Periocular Identification During Covid-19

The global pandemic of novel coronavirus that started in 2019 has seriously affected daily lives and placed everyone in a panic condition. Widespread coronavirus led to the adoption of social distancing and people avoiding unnecessary physical contact with each other. The present situation advocates the requirement of a contactless biometric system that could be used in future authentication systems which makes fingerprint-based person identification ineffective. Periocular biometric is the solution because it does not require physical contact and is able to identify people wearing face masks. However, the periocular biometric region is a small area, and extraction of the required feature is the point of concern. This paper has proposed adopted multiple features and emphasis on the periocular region. In the proposed approach, combination of local binary pattern (LBP), color histogram and features in frequency domain have been used with deep learning algorithms for classification. Hence, we extract three types of features for the classification of periocular regions for biometric. The LBP represents the textual features of the iris while the color histogram represents the frequencies of pixel values in the RGB channel. In order to extract the frequency domain features, the wavelet transformation is obtained. By learning from these features, a convolutional neural network (CNN) becomes able to discriminate the features and can provide better recognition results. The proposed approach achieved the highest accuracy rates with the lowest false person identification.     

Effect of functionalized multiwalled carbon nanotubes on weather degradation and corrosion of waterborne polyurethane coatings

A series of waterborne polyurethane/functionalized multiwalled carbon nanotube (WBPU/f-MWCNT) nanocomposite dispersions was prepared using three defined concentrations of 0.5, 1.0 and 2.0 wt% carboxyl functionalized multiwalled carbon nanotubes (f-MWCNTs). All dispersions were coated on mild steel and exposed under natural weather condition for a maximum of 365 days. Both exposed and unexposed coatings were characterized by potentiodynamic polarization (PDP) and X-ray photoelectron spectroscopy (XPS) analyses. The pristine WBPU coating showed slight degradation and corrosion protection. Inclusion of a higher content of f-MWCNTs significantly improved both the degradation and corrosion protection efficiencies of the coatings. Maximal degradation and corrosion protection was observed when 2.0 wt% f-MWCNT was mixed with WBPU for all of the coatings.     

Functional verification of instruction processing units through control flow modeling

The design verification of state-of-the-art high-performance microprocessors has become a significant challenge for test engineers. Deep pipelines, multiple execution units, out-of-order and speculative execution techniques, typically found in such microprocessors, contribute much to this complexity. Conventional methods, which treat the processor as a logic state machine or apply architectural level tests, fail to provide coverage of all possible corner cases in the design. This paper presents a functional verification method for modern microprocessors, which is based on innovative models of the microprocessor architecture, intended to cover the testing of all corner cases. In order to test the models presented in this work, an architecture independent coverage measurement system has been developed. The models were tested with both random code and real world applications in order to determine which of the two achieves higher coverage.     

Solar Carboreduction of Alumina Under Vacuum

A preliminary study on carboreduction of alumina under vacuum, which was necessary before the solar reactor design, has been performed using an induction heater equipped with a graphite susceptor as the sample holder surrounded by a ceramic tube serving as the metal vapor deposit site. The primary objective was to study the forward and backward reactions as a function of temperature and CO partial pressure. It was concluded that at reaction temperatures above 1600°C and at an average CO partial pressure below 0.2 mbar, the amount of residual by-products in the graphite crucible was negligible, whereas tests with an average CO partial pressure of 2.6 mbar required temperatures above 1800°C to convert the stoichiometric reactants pellets fully. It was concluded that pure aluminum can be found only at deposit sites with temperatures below 600–700°C in tests with temperature and pressure suitable to prevent the volatile suboxide formation in the forward reaction. Based on these results, the solar reactor was designed with a sharp temperature drop from the hot to the cold area. The results of solar tests with different levels of CO partial pressure and temperature conditions reveal that the alumina to aluminum conversion is about 90% for reaction temperatures above the minimum temperature required for full conversion as predicted by the thermodynamic calculations at the appropriate pressure. However, at lower temperatures, a significant amount of solid Al₄C₃, Al₄CO₄, and volatile Al₂O can be formed in the forward reaction, leading to an increase of the residual by-product in the reactant holder as well as lower purity of the aluminum product and an increase of the alumina content in the deposits at the cold reactor’s zone. The observed nanocrystalline and amorphous morphology of the deposits caused by fast cooling in the cold zone will also be discussed.     

A novel method of reducing melting temperatures in SnAg and SnCu solder alloys

With the increasing use of lead-free solder alloys in modern electronics, low melting materials are often required to protect the heat-sensitive parts during soldering operation. Alloy systems based on Sn/Cu/Ag offer more reliable solutions and address the current problems involved with soldering process. Nanoparticles melt relatively at low temperatures compared to their bulk counter parts and we introduce a robust method of synthesizing nanoscale solder pastes for wave soldering applications. Nanoparticles of Sn-3.5Ag and Sn-0.7Cu alloys were prepared with stir casting followed by mechanical attrition. The size dependent melting properties of the eutectic alloys were studied by differential scanning calorimetry technique and the results showed a reduction of 4.7 and 5.0 °C melting temperatures in the alloys when reduced from bulk to 92 nm and 96 nm sizes respectively. The nanosize effects were also theoretically calculated and compared with experimental data.