Variation of Soil PH Using Circularly Polarized Light

The use of  a commercial circular polarizer to produce polarized light from a 85W conventional source and its influence on the pH of sandy loam soils is presented. The role of soil pH in the determination of plant nutrient requirements has made its monitoring important for plant growth and development. The study was designed to determine the effectiveness of using circularly polarized light to amend the level of soil acidity and alkalinity. Samples of acidic and alkaline sandy loam soils were exposed to a collimated beam of the circularly polarized and the pH and temperature measured at 1 - hour intervals for 8 hours in a dark room. The control was soil samples exposed to unpolarized light from another 85W conventional source. All the samples were replicated three times. The results show that circularly polarized light has the ability to significantly increase the pH of sandy loam acidic soil while it had no appreciable effect on the alkaline soil . This could provide an alternate non - chemical means of managing highly acidic sandy loam soils. Key words: Soil pH,  Circular Polarizatio

Small - Scale Surface Mining in Tarkwa - Nsuaem Municipality in Western Ghana and its Effect on Soil Physical Properties

Small - scale surface mining in Tarkwa - Nsuaem municipality in western Ghana and its effect on soil physical properties is presented in this study. The rising rate of land degradation by the small - scale surface miners in the study area has created a situation in which farmlands are becoming scarce and farmers are left with no choice than to use mined - out lands. The study set out to measure the physical properties of soil from mined - out lands to determine their suitability for use for agricultural purposes. One set of samples comprising soil from mined and unmined sites were randomly collected using a cylindrical metal core of known volume. After recording their wet weights, the samples were then oven dried at 105°C for 24 hours after which their dry weights were also recorded. The bulk density, porosity, solid space, mass wetness and void ratio were then calculated. The procedure was repeated for three other sites in the study area. The results showed that the mined soil, in its current state, was unsuitable for use by farmers for agricultural purposes because it was compacted, less porous, susceptible to erosion, dry and could barely support plant life. It was recommended that practices that maintain or increase soil organic matter which leads to high pore space and low bulk density be adopted to restore the mined - out lands to their natural state. Keywords: Bulk density, Porosity, Pore space, Mass wetness, Void rati

Allelopathic Effect of Topsoil Extract From Tectona grandis L. Plantation on the Germination of Lycopersicum esculentum

The use of topsoil extracts transferred from Tectona grandis L. plantation to explore similar effects and use of the leaf, bark and root extracts on germination and growth of Lycopersicum esculentum is presented. The study was designed to determine the effect of variation of masses of topsoil extracts from teak plantation on the germination and growth response of tomato seeds planted on another soil whose physico - chemical analysis indicate that it can support plant growth. The topsoil extracts were collected in 5kg, 5.5kg, 6kg and 6.5kg packs and respectively spread on 4 mini - plots each with 3 replications and containing 50 planted tomato seeds. The control was the mini - plot without any topsoil extracts. The results showed that the topsoil extracts were able to suppress the germination of the tomato seeds and the effect increased with the mass used. There was a significantly progressive decrease in the mean tall lengths of the seedlings with mass of topsoil indicating a growth inhibition. However, the effect was not very much pronounced in the comparison of the mean values of the short lengths of the seedlings. Key words: Allelopathy,  topsoil extracts, germinatio

DIGITAL TRANSFORMATION EDUCATION: CHALLENGES, EFFECTIVENESS, AND PERCEPTIONS OF COMPUTER-ASSISTED INSTRUCTION APPLICATION IN PHYSICS CLASSROOM

Digital Transformation Education has received greater attention in teaching and learning, however, there is a scarcity of studies on the challenges, effectiveness, and perceptions of Computer-Assisted Instruction (CAI), especially in the Colleges of Education (CoE). In addressing these, the study used the mixed method research design using 12 Physics tutors and 254 Physics students from 3 CoE purposively selected from the Sekyere South District and the Mampong Municipality. Interviews and questionnaires were used for data collection and data analysis was done using Statistical Package for Social Sciences ¬(IBM SPSS), version 26.1, employing descriptive statistics and thematic analysis. The results indicated that Physics tutors generally face a high level of challenges, with inadequate technological resources and limited financial support posing the greatest hindrances. In response, tutors employed various strategies including personal investment in internet bundles and advocacy for institutional intervention. It was again found that both quantitative and qualitative findings converged after merging and that the qualitative findings agreed with the quantitative findings. It was concluded that tutors of Physics in the CoE in the Mampong Municipality and the Sekyere South District encounter challenges during their integration of CAI in their Physics lessons. However, since students of Physics in the CoE perceive the use of CAI as very positive to their academic lives, it was recommended that using CAI for teaching and learning Physics in the colleges of education should be fortified.  Article visualizations

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Synthesis and electromagnetic characterization of polycaprolactone filled with hematite and OPEFB fiber nanocomposite

The most common materials used for microwave absorbing applications are ferrites. However, ferrites are expensive, heavy, non – biodegradable and have low dielectric loss properties especially at high frequencies. This study presents the development of novel composites using recycled ferrite in conjunction with biodegradable oil palm empty fruit bunch (OPEFB) fiber and polycaprolactone (PCL) as an alternative for reducing the limitations of ferrite – based microwave absorbing materials. Hematite (α – Fe2O3) was recycled from mill scale waste (steel waste) material and the particle sizes reduced to nanosize after several hours of high energy ball milling (HEBM). The relationship between the reduced particle sizes and the dielectric properties was then determined. α – Fe2O3/PCL and α – Fe2O3/OPEFB fiber/PCL nanocomposites with different loadings (5 to 25%) of 16.2 nm α – Fe2O3 nanofiller were fabricated and characterized for their dielectric, magnetic and microwave absorption properties. The material composition and structural properties were analyzed using X – ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X – ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer – Emmett – Teller (BET) techniques. The relative complex permittivity and permeability of the samples were respectively measured using the open – ended coaxial probe and the rectangular waveguide techniques while the microwave absorption properties were measured with the microstrip at 1 GHz to 4 GHz. The results showed that the relative complex permittivity of the recycled α – Fe2O3 increased with reduced particle size. The dielectric loss factor (ɛ'') increased from 0.17 to 0.46 when the particle size was reduced from 1.73 μm to 16.2 nm at 8 GHz. Within the X – band (8 GHz – 12 GHz) frequency range, the relative complex permittivity properties of the recycled α – Fe2O3 particles were higher as compared to a commercial α – Fe2O3 (Alfa Aesar). Additionally, the relative complex permittivity (ε*) values of the nanocomposites increased with recycled α – Fe2O3 nanofiller content and were higher in the α– Fe2O3/OPEFB/PCL nanocomposites than the α – Fe2O3/PCL nanocomposites. This is due to the high loss factor of the incorporated OPEFB fiber. Attenuation and power loss due to absorption equally increased with recycled α – Fe2O3 nanofiller loadings. At 2.4 GHz, the range of attenuation for the α– Fe2O3/OPEFB/PCL nanocomposites was from 2 dB to 2.6 dB while the power loss values were from 15 dB to 17.3 dB. The attenuation values for the α – Fe2O3/PCL nanocomposites were however from 1.8 dB to 2 dB while the power loss values were in the range of 13.6 dB to 15.2 dB. The recycled α–Fe2O3/OPEFB/PCL nanocomposites can therefore serve as promising alternatives for microwave absorbing applications in the 1 – 4 GHz in view of their low cost, low density, biodegradability and attractive absorption behaviour. Recycled hematite at reduced particle size has the potential for use as a filler in other polymeric composites and its application can reduce the cost of ferrite – based microwave absorbing materials significantly without compromising the absorption efficiency of the materials

Enhancement of complex permittivity and attenuation properties of recycled hematite (α-Fe2O3) using nanoparticles prepared via ball milling technique

The purpose of this study was to synthesize high-quality recycled α-Fe2O3 to improve its complex permittivity properties by reducing the particles to nanosize through high energy ball milling. Complex permittivity and permeability characterizations of the particles were performed using open-ended coaxial and rectangular waveguide techniques and a vector network analyzer. The attenuation characteristics of the particles were analyzed with finite element method (FEM) simulations of the transmission coefficients and electric field distributions using microstrip model geometry. All measurements and simulations were conducted in the 8–12 GHz range. The average nanoparticle sizes obtained after 8, 10 and 12 h of milling were 21.5, 18, and 16.2 nm, respectively, from an initial particle size of 1.73 µm. The real and imaginary parts of permittivity increased with reduced particle size and reached maximum values of 12.111 and 0.467 at 8 GHz, from initial values of 7.617 and 0.175, respectively, when the particle sizes were reduced from 1.73 µm to 16.2 nm. Complex permeability increased with reduced particle size while the enhanced absorption properties exhibited by the nanoparticles in the simulations confirmed their ability to attenuate microwaves in the X-band frequency range

Effect of microstructure on complex permittivity and microwave absorption properties of recycled α-Fe2O3 nanopowder prepared by high-energy ball milling technique

This study was aimed at investigating the effect of microstructural variations on relative complex permittivity and microwave absorption properties of recycled α-Fe2O3, following application of high-energy ball milling technique to modify particles into nanopowder. Three portions of recycled α-Fe2O3 granules were separately milled for 8 h, 10 h and 12 h respectively and their microstructural characteristics were examined using X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM) and Brunauer-Emmett-Teller (BET) analysis. This was followed by relative complex permittivity and microwave absorption characterizations which were conducted at X-band microwave frequency range using the rectangular waveguide technique in connection with a vector network analyzer. Results established interfacial lattice defects and imperfections in the milled portions which became more pronounced with reduced crystallite sizes, and contributed to enhanced interfacial polarization process, leading to increased relative complex permittivity and microwave absorption properties of the recycled α-Fe2O3 nanopowders. The smallest estimated crystallite size of 11.1 nm was obtained after 12 h of milling with ɛ r = 12.1–0.46j at 8 GHz, which was reduced to ɛ r = 11.0–0.34j at 12 GHz while its power loss values varied between 18.3 dB and 23.3 dB in the 8–12 GHz range. A positive correlation was identified that connects microstructural variations with relative complex permittivity and power loss, and could be exploited to tune the microwave absorption properties of the recycled α-Fe2O3 particles

Complex permittivity and microwave absorption properties of OPEFB fiber–polycaprolactone composites filled with recycled hematite (α-Fe2O3) nanoparticles

Recycled hematite (α-Fe2O3) nanoparticles with enhanced complex permittivity properties have been incorporated as a filler in a polycaprolactone (PCL) matrix reinforced with oil palm empty fruit bunch (OPEFB) fiber for microwave absorption applications. The complex permittivity values were improved by reducing the particle sizes to the nano scale via high-energy ball milling for 12 h. A total of 5–20 wt.% recycled α-Fe2O3/OPEFB/PCL nanocomposites were examined for their complex permittivity and microwave absorption properties via the open ended coaxial (OEC) technique and the transmission/reflection line measurement using a microstrip connected to a two-port vector network analyzer. The microstructural analysis of the samples included X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). At 1 GHz, the real (ε′) and imaginary (ε″) parts of complex permittivity of recycled α-Fe2O3 particles, respectively, increased from 7.88 to 12.75 and 0.14 to 0.40 when the particle size was reduced from 1.73 μm to 16.2 nm. A minimum reflection loss of −24.2 dB was achieved by the 20 wt.% nanocomposite at 2.4 GHz. Recycled α-Fe2O3 nanoparticles are effective fillers for microwave absorbing polymer-based composites in 1–4 GHz range applications

Effects of recycled Fe2O3 nanofiller on the structural, thermal, mechanical, dielectric, and magnetic properties of PTFE matrix

The purpose of this study was to improve the dielectric, magnetic, and thermal properties of polytetrafluoroethylene (PTFE) composites using recycled Fe2O3 (rFe2O3) nanofiller. Hematite (Fe2O3) was recycled from mill scale waste and the particle size was reduced to 11.3 nm after 6 h of high-energy ball milling. Different compositions (5–25 wt %) of rFe2O3 nanoparticles were incorporated as a filler in the PTFE matrix through a hydraulic pressing and sintering method in order to fabricate rFe2O3–PTFE nanocomposites. The microstructure properties of rFe2O3 nanoparticles and the nanocomposites were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The thermal expansion coefficients (CTEs) of the PTFE matrix and nanocomposites were determined using a dilatometer apparatus. The complex permittivity and permeability were measured using rectangular waveguide connected to vector network analyzer (VNA) in the frequency range 8.2–12.4 GHz. The CTE of PTFE matrix decreased from 65.28×10−6/°C to 39.84×10−6/°C when the filler loading increased to 25 wt %. The real (ε′) and imaginary (ε″) parts of permittivity increased with the rFe2O3 loading and reached maximum values of 3.1 and 0.23 at 8 GHz when the filler loading was increased from 5 to 25 wt %. A maximum complex permeability of (1.1−j0.07) was also achieved by 25 wt % nanocomposite at 10 GHz