Determination of activity concentration level of 226RA, 40K and 232TH in soil within Igabi Local Government Area of Kaduna State, Nigeria

This paper is aimed at determining the levels of primordial radionuclides 226Ra, 232Th, and 40K in selected sampling sites within Igabi local government area of Kaduna state, Nigeria using Gamma Ray Spectrometry. Radioactivity levels of fifteen samples taken from seven different locations within Igabi local Government area of Kaduna state, Nigeria were measured by means of gamma-ray spectrometry with () detector to determine activity concentration of 40K, 226Ra and 232Th. Results obtained indicate highest activity concentration of 40K, 226Ra and 232Th from soil samples collected from NOU (502.4883 −1), BP1 (759.0962 −1) and EC2 (127.5941−1).The mean activity of 40K (237.4184 −1)was found to be lower than the world average of 420 −1; that of 232Th (86.2182 −1) was found to be above the world average of 50 −1; and that of 226Ra (128.3507 −1) was found to be lower than the world average of 370 −1.

Effect of aggregation on dielectric property of MWCNT/PDMS nanocomposite

Highly graphitized nucleophilic group functionalized Multiwall carbon nanotubes are utilized to fabricate PDMS/FMWCNTs nanocomposites with low weight fraction (0.1 wt%). The effect of solvents on dispersion of FMWCNTs is studied. THF shows higher dispersion power in comparison with chloroform. The dielectric constant is measured using impedance analyzer in the range of 106-109 Hz. The result indicate, the dielectric property of FMWCNTs/PDMS nanocomposite could be manipulated with proper mixing techniques and adjustment of curing time

Stitched Transmission Line for Broadband Operations

Wearable stitched transmission lines made from stripped RG174 and textile materials are introduced for broadband operations. The stitched transmission lines which are 150 mm long consists of an inner conductor surrounded by a tubular insulating layer. For shielding purposes, the structures are stitched into a denim material with conductive threads. The performances of the stitched transmission lines with three different stitch patterns, Double Overlock, Flatlock stitch and Ric-Rac stitch were investigated and results obtained confirm that Ric-Rac stitched transmission line has fewer DC losses than the three stitched transmission lines for frequencies up to 1 . However, beyond that up to 2.4 and above, it was observed that the Flatlock stitched transmission line and the Double Overlock stitched transmission line have fewer radiation losses compared to the Ric-Rac stitched transmission line. Similarly, the performance of the stitched transmission line when bent through curved angles of 90° and 180° was considered, and a much better 21 was observed with a curved angle of 180° for frequencies below 2.1 , with radiation loss increasing afterwards. Finally, the sensitivity of the design to manufacturing tolerances, with changes in cross-sectional dimensions of the stitched transmission line and the transmission characteristics with different textile substrates were both considered. While simulated results showed that the stitched transmission line is sensitive to small variations in its circular dimensions, measured results conversely showed that Denim and Felt materials can be used as a substrate without any significant effect on its propagation characteristics

Enhancement of complex permittivity and attenuation properties of activated carbon derived from oil palm fruit fiber for microwave application

This study aimed to synthesize activated carbon (AC) from empty oil palm fruit bunch (OPEFB) fiber to enhance its complex permittivity properties by modifying the particle size and surface area via physical activation. Sample characterizations of complex permittivity were conducted using open-ended coaxial technique and a vector network analyzer. The absorption properties were analyzed using the finite element method (FEM) simulations of the transmission coefficients and the distribution of electric fields via the microstrip models. Simulations and measurements were all carried out within the range 8–12 GHz. The initial surface area of the unactivated sample was 4.02, after 700, 750, and 800 °C activation, 730.40, 814.00, and 927.01 m2/g was obtained respectively. With increased surface area, the dielectric constant and loss factor values increased and attained maximum values of 6.13 and 0.83 at 8 GHz, respectively from initial values of 3.63 and 0.52, as the surface area increased from 4.02 to 927.01 m2/g. The improved absorption properties displayed by the AC in the simulations demonstrated their capacity to attenuate X-band microwaves

Silicon nanowire interface circuit for biosensing applications

Detection and quantification of biological and chemical species are critical to many areas of the life sciences and health care, from disease diagnosis to drug screening. Central to detection is the transduction of the signal associated with the sensing event. Advances in nanotechnology have led to the development of the silicon nanowire which is faster, smaller, greener and cheaper. These nanowires have a very narrow diameter similar to that of the chemical and biological species to be sensed making them perfectly suited for biosensing. The top-down fabricated silicon nanowires is used in this work due to its oxide-coated surface and ease of integration with other microelectronic components. Due to the ultra-small output signal of the nanowire, bulky equipments which are often time consuming and expensive are used for reading the signal. This work attempts to build a circuit that can be interfaced with the nanowire to make the signal readable hence the sensor will become portable thereby increasing its utility to being a point-of-care and field-testing device

Synthesis of carbon nanotubes using microwave oven

Advances in the synthesis of carbon nanotubes (CNTs) have emerged as a result of the properties and potential application of carbon nanotubes. We demonstrated a simple approach of using domestic microwave oven with 600W at 2.45 GHz which was modified to produce CNTs from a carbon source on coated silicon oxide substrate. The Raman spectroscopy showed the graphitic nature of the obtained CNTs, with intensity ratio ID/IG calculated to be 0.92. Field emission scanning electron microscope (FESEM) reveals CNTs are produced on the substrate surface with outer diameter range of 11-44 nm and length of about 0.25 μm. HRTEM further confirmed the graphitic nature of the CNTs obtained. The purity of the nanotubes was analyzed with energy dispersive X-ray (EDX) which showed atomic weight of 98% carbon purity. This paper shows that domestic microwave oven can be used to synthesize CNTs with polymer as the carbon source via plasma catalytic decomposition which was found to be fast, economical and clean technique

Plasma technique of carbon nanotube synthesis using commercial microwave oven

Carbon nanotubes (CNTs) research have been the focus of revolutionizing nanotechnology, which stimulate attention from scientific communities to understand its exceptional properties, syntheses and potential applications such as sensor, field emission, hydrogen storage and biomedicine. Advances have been made by researchers, working extensively to develop diverse techniques such as arc discharge,laser ablation, thermal chemical vapor deposition and plasma enhanced chemical vapor deposition to synthesize CNTs, but these techniques are expensive and time consuming. The aim in this study is to develop a plasma technique using commercial microwave oven, to synthesize CNTs which can be more economical and less time consuming. The technique employed comprises of two parts; first part id to monitor the pressure level and plasma region while the second part deals with synthesis where require carbon source and catalyst are investigated. Commercial microwave oven with operating power of 600 W was used to irradiate the carbon source and coated substrate at atmospheric pressure with 2.45 GHz frequency, which leads to the formation of plasma in the tubular reactor. From the study shows that for CNTs growth, certain parameters are necessary to be controlled such as plasma, pressure at 0.81 mbar, temperature at 750 °C, catalyst (iron(III) nitrate nonahydrous), and carbon source (Polyethylene). The obtained CNTs were characterized via Raman spectroscopy which shows CNTs quality of 1.01, average tubes diameter at (6.0 to 10.0) ± 0.5 nm, twisted and oriented structures with interlayer spacing of about 0.35 nm and carbon purity of about 99.86%. The plasma technique results obtained shows that the technique is economical and fast process of synthesis