Structural and spectroscopic properties of zinc-tellurite doped samarium glass embedded with gold nanoparticles

Modification in the structural, thermal and optical properties of samarium ions (Sm3+) doped zinc-tellurite glass with gold nanoparticles (Au NPs) embedment was studied. In this regard, two series of zinc-tellurite glass systems with composition (80-y)TeO2-20ZnO-ySm2O3, where 0.0 = y = 2.0 mol% and (79- x)TeO2-20ZnO-1Sm2O3-xAuCl3, where 0.00 = x = 0.10 mol% were prepared using melt quenching technique. Sm3+ ions and Au NPs concentration dependent structural, thermal and optical properties of these glass samples were determined. Structural characterizations were made using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy. Thermal properties were measured by differential thermal analyzer (DTA). The existence, size, and morphology of Au NPs in the glass matrix were examined via transmission electron microscopy (TEM). Optical properties of glass samples were determined using UV-Vis-NIR absorption and photoluminescence (PL) spectroscopy. The occurrence of broad hump in the XRD patterns verified the amorphous nature of glass samples. FTIR spectra exhibited three major bands which were allocated to the TeO3, TeO4 units and bending vibrations of Te-O-Te linkages or Zn-O vibrations. Raman spectra showed the bending vibrations mode of Te-O-Te and stretching vibration modes of nonbonding oxygen linked to the TeO4 and TeO3 units. TEM images manifested the existence of Au NPs of average diameter 17.12 nm. Both glass systems exhibited thermal stability and glass forming ability which was increased from 80 °C to 143 °C and from 0.37 to 1.03, respectively with the increase of Au NPs contents. The absorption spectra displayed ten prominent peaks corresponding to the transitions from the ground state (6H5/2) to various excited states of Sm3+ ions. Surface plasmon resonance (SPR) bands of Au NPs were detected at 652 and 715 nm. The bonding parameters of the prepared glass samples that were calculated from the absorption spectra revealed the covalent/ionic nature of the rare earth-ligand (Sm-O) bond. Optical band gap energies and the Urbach energy values were determined. The ligand field parameters estimation showed that the crystal field strength and the degree of covalency between ions were increased. Besides, the interelectronic f-f repulsion Racah parameters were decreased with increasing NPs contents. The room temperature PL spectra disclosed four prominent emission bands centered at 562 nm (green), 600 nm (orange), 644 nm (red) and 709 nm (red) which were assigned to the 4G5/2 ? 6H5/2, 4G5/2 ? 6H7/2, 4G5/2 ? 6H9/2 and 4G5/2 ? 6H11/2 transitions, respectively. Overall, the structural, thermal and optical properties of the studied tellurite glass system were strongly influenced by the embedment of Au NPs in the glass matrix. The alteration in the overall properties was attributed to the mediation of Au NPs surface plasmon, radiative transitions and cross-relaxation effects. The improvement in the properties of these glasses may be beneficial for different optical applications

Phytochemical, High Performance Liquid Chromatography and Antimicrobial Evaluations of the Ethanolic Root Extract of Phoenix dactylifera L.

Bioactive compounds from plants have received a great deal of interest from scientists all over the globe for development of drugs. This study was aimed at evaluating phytochemicals, High Performance Liquid Chromatography (HPLC) and antibacterial activities of ethanolic root extract of Phoenix dactylifera L. (date plant) against some clinical isolates. Roots of date plant were dried and extracted with ethanol using the cold maceration method before concentrating it with water bath at 45 oC. The phytochemicals were identified using HPLC based on their individual retention time. Antibacterial activities of the methanolic root extract were assessed against some clinical isolates including Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes, and Pseudomonas aeruginosa utilizing agar disc diffusion method. The percentage yield of ethanol extract was 0.3892%. The result of the phytochemical screening revealed the presence of carbohydrate, phenols, tannins, saponins, flavonoids, cardiac glycosides, steroids, alkaloids and terpenes at various retention time of 2.853, 3.235, 4.129, 4.713, 6.722, 8.954, 11.228 and 22.912 min. Compounds identified include phenolic acid (caffeic acid) and two flavonoids (rutin and quercetin). The zone of inhibition diameter ranged from 15 to 19 mm. The maximum zone of inhibition was detected against Streptococcus pyogenes, (19 mm). Staphylococcus aureus and Klebsiella pneumoniae were inhibited with 17 mm and 16 mm zone of inhibition respectively, followed by Pseudomonas aeruginosa which had the least zone of inhibition (15 mm). The result of the present study suggests that the root of Phoenix dactylifera L. possesses important phytochemical components with antibacterial activity that could be possibly exploited for pharmaceutical development

Split-plot Central Composite Experimental Design Method for Optimization of Cake Height to Achieve desired Texture

In many industrial experimental situations, the levels of certain factors under investigation are much harder to change than others due to time and/or cost constraints. An appropriate approach to such situations is to restrict the randomization of the hard-to-change (HTC) factors, which leads to a split-plot structure. This work designs and conducts a split-plot central composite experiment for optimizing cake height using oven temperature(Factor A) as the HTC factor, amount of flour (B), baking powder (C), and amount of milk (D) as the easy-to-change (ETC) factors. A second-order split-plot central composite design (CCD) model was fit to the generated data and analyzed using generalized least squares (GLS). A stationary point, which gives optimum cake height, was then determined. The results show that main effects of oven temperature, flour, baking powder, and milk were highly significant on the cake height . Their quadratic effects were also significant except that of the flour. The flower/baking powder interaction effect was significant. The fitted model  accounted for about 95% of the total variability in the cake height data. The observed optimum cake height was ̂ at a stationary point: A . This study has established the potentials of response surface experiments in optimizing products in food industries. Keywords: Experiment, split-plot CCD, Cake height, Design, Stationary point.&nbsp

The Relevance of Entrepreneurial Orientation to Students Entrepreneurial Intention: Evidence from Federal University Dutse (FUD)

This paper examined the dimensions of entrepreneurial orientation and its relevance to student’s entrepreneurial intention among Federal University Dutse final year students as at 2017­­/2018 academic session. The study adopts cross-sectional research design using quantitative questionnaire approach to collect the data. To validate the model, data from 282 final year students were analysed using the Partial Least Squares Structural Equation Modelling (PLS-SEM). Overall, the study revealed that dimensions of innovativeness, pro-activeness and risk-taking are significantly and positively relevance to student entrepreneurial intention. The study used Human Capital Theory (HCT) as a theoretical foundation of the study. This study served as one of the pioneering study with regard to HCT in testing relationship of this nature. This study recommended that other researchers should use this theory to include other dimension of entrepreneurial orientation for further validation. This study also contributes to the current literatures by extending the used of entrepreneurial orientation which is still rare in student entrepreneurial intention literatures. As suggestion to policy, the government should guarantee not only inspiring students with entrepreneurship education but also inculcate the spirit of innovativeness proactiveness, and risk-taking among  youths as it has relevance in explaining students entrepreneurial intention

INFLUENCE OF IRON CONTENT AND PLASTIC DEFORMATION ON THE MECHANICAL PROPERTIES OF 8011-TYPE Al-Fe-Si ALLOY

This paper examines the effect of iron content and plastic deformation on the mechanical properties of wrought Al-Fe-Si alloy. Seven samples each of dimension 240mm x 140mm x 7mm were cast for each aluminium alloy plate containing iron content of 0.708%, 0.909% and 0.931% by chill casting method. As-received commercial aluminium alloy 8011 has an iron content of 0.857% and it was cut into seven samples of the same geometry. Cold rolling experiment was carried out from 30% to 80% reduction in thickness. The mechanical properties of the alloys were investigated. The results showed that the maximum ultimate tensile strength obtained for alloys 0.708%Fe and 0.857%Fe were 171.45MPa and176.45MPa respectively both occurred at 60% reduction in thickness while alloys 0.909%Fe and 0.931%Fe respectively have 163.16MPa and 170.00MPa at 80% reduction in thickness. An increase in iron content led to corresponding decrease in tensile strength but at 80% reduction in thickness, the strength increase with iron content for alloys of 0.9%Fe and above. The micro-vicker hardness values increases, reaching the peak and then decreases with increasing percentage deformation. http://dx.doi.org/10.4314/njt.v35i1.1

Postharvest losses, causes and mitigation in tomato transportation: a systematic review

Purpose: The study aimed to provide an overview of tomato loss during road transportation with specific interest in the causes of the postharvest loss, postharvest loss mitigation measures, as well as research focus and trends over the past few decades. Findings: Transport conditions significantly affect tomato quality, influenced by factors like vehicle specifications and road conditions, which contribute to mechanical damage. Post-harvest losses stem from various factors such as the usage of inadequate harvesting tools, inefficient handling and transport equipment, usage of inappropriate packaging materials, poor temperature management and rough handling of fresh fruits as well as substandard road infrastructure. These issues collectively result in substantial losses, reaching up to 60%, notably impacting developing countries. Limitations: The study focused on existing literature published in English. Consequently, it may not offer a comprehensive overview, as other studies with abundant information on the subject might be written in languages not covered by this study’s language restriction. Directions for future research: Future research should prioritize investigating the impact of mechanical stress, such as vibration and impact loads, experienced by fruits like fresh tomatoes during road transport and material handling. Additionally, there is a need to assess the effectiveness of different packaging materials in safeguarding transported tomatoes against mechanical stress

Microorganisms Associated with Volatile Organic Compound Production in Spoilt Mango Fruits

Microorganisms associated with the production of volatile compound in spoilt mango fruits sold in Sokoto town were isolated and identified. The organisms include seven species of bacteria and a species of yeast. These include Bacillus pumilus, Bacillus firmus, Brevibacillus laterosporus, Morganella morganii, Paenibacillus alvei, Staphylococcus saccharolyticus, Listeria monocytogenes and Candida krusei respectively. GC-MS analysis revealed the presence of eleven and sixteen volatile organic compound in the healthy and spoilt ripe mango fruits. Octadecanoic acid, oleic acid, 1 – Butanol, 3 – methyl-, carbonate (2:1) and 3,7 – Dimethyl nonane were common to both healthy and spoilt fruits with the first three having higher concentration in healthy fruits than spoilt while the later had higher concentration in the spoilt. One methyl group of 3,3- Dimethyl hexane in healthy fruit was shifted to position two to yield 2,3-Dimethyl hexane in the spoilt fruits. 2,2-Dimethylbutane, Methyl(methyl-4-deoxy-2,3-di-O-methyl.beta.1-threo-hex-4-enopyranosid) urinate, 3-(4-amino-phenyl)-2-(toluene-4-sulfonylamino)-propionic acid, 2-Methyl-3-heptanone, 3,5-Nonadien-7-yn-2-ol, (E,E), Butanoic acid, 1,1-dimethylethyl ester, 1-methyl-3-beta.phenylethyl-2,4,5-trioxoimidazolidine, Pentanoic acid, 2,2-dimethyl, ethyl ester (Vinyl 2,2-dimethylpentanoate), 4-Methyurazole, 1-Tridecyn- 4 – 9 – ol, 1-Hexyl-1-nitrocyclohexane were unique to spoilt fruits. This study suggests that these unique volatile metabolites could be exploited as biomarkers to discriminate pathogens even when more than one disease is present thereby curbing post harvest loss during storage after further validation and the volatile organic compound could form the basis for constructing a metabolomics database for Nigeria

Prevalence of Escherichia coli some public water sources in Gusau Municipal, North Western Nigeria

This study investigated the presence of Escherichia coli from some public water sources in Gusau municipal, north- western Nigeria. This was done by determining the total coliform counts and the presence of Escherichia coli and its antibiotic susceptibility profile. A total of 180 well 60 tap and 60 packaged water samples were obtained from Gusau municipal on weekly basis over a period of seven month (August, 2006-Feb, 2007) covering part of rainy and dry seasons. Standard procedures were used for the identification of Escherichia coli and for estimating total coliform counts. All samples had coliform counts higher than the international standard recommended by the World Health Organization. Results of biochemical analysis of the samples showed that out of 63 confirmed Escherichia coli isolated, 41 (45.5%) were from well water, tap water had 14 (23.3%) while packaged water had 8(13.3%).The susceptibility profile of the isolates to nine antimicrobial agents indicated that majority of the isolates were highly susceptible to Chloramphenicol, Gentamycin, Perrfloxacin, Tarivid, Augmentin, Streptomycin, Sparfloxacin, and Ciprofloxacin, moderate susceptibility to Septrin and resistant to Amoxacilin were observed. None of the water samples met the WHO standards for drinking water and thus pose a serious health risk to its consumers and users if not properly treated. Key words: Bacteriological quality, Escherichia coli, Prevalence, susceptibility profile, public water sources, Gusau

Assessment of Radon Concentration in Groundwater with Associated Human-Health Implications around Bagwai and Shanono Artisan Gold Mining Site Kano State, Northwestern Nigeria

This study assesses the activity concentration of Radon in underground water around Bagwai and Shanono artisan gold mining Sites in Kano State, Northwestern Nigeria. A total of (39) underground water samples, including sixteen (16) from boreholes and twenty-three (23) from hand-dug wells, were randomly collected. The activity concentration of Radon was analyzed using a portable radon detector, Rad7, from DURRIDGE Company. The results show that the radon concentration in all the water samples ranges from 4.13 to 45.24 Bq/l, with an average value of 20.13 Bq/l. The calculated total annual effective dose due to both ingestion and inhalation for different age groups ranges from 42.40, 57.60 and 65.30 (µSv/y) to 457.10, 622.06 and 704.60 (µSv/y), with an average value of 203.32, 276.70 and 313.51 (µSv/y) for adults, children, and infants respectively. The total excess lifetime cancer risk for different age groups varies from 0.00149, 0.00202 and 0.0247 to 0.0160, 0.0220 and 0.0247 with mean values of 0.00703, 0.00956 and 0.0109 for adults, children, and infants. The obtained results are higher than the internationally recommended limits set by USEPA of 4 to 40Bq/l and the International Commission on Radiological Protection (ICRP) value of 0.1mS/y; thus, the water in the study area is not suitable for drinking and other domestic purposes. Hence, remedial action needs to be taken by the authorities to ensure the continuous utilization of water within the study area

The Role of Power Electronic Converters in Microgrid Technology: A Review of Challenges, Solutions, and Research Directions

The paper is on the role of power electronic converters in microgrid technology: A review of challenges, solutions and research directions. The objective of the paper is to perform a comprehensive overview of the role of power electronic converters in microgrid technology, focusing on challenges, solutions, and research directions. Findings revealed that major challenges of power electronic converters integration in microgrid technology are voltage and frequency regulation issues, power quality issues, creative management and coordination challenges, and Integration of renewable energy sources. The solutions to these problems are advanced control algorithms such as Model Predictive Control (MPC); deployment of active power filters or harmonic compensators to reduce harmonic distortion and improve power quality; iimplement a centralized control system with centralized monitoring controllers to coordinate the operation of several converters and ensure consistent operation; and combining multiple renewable energy sources in a hybrid energy system to diversify generation sources and reduce the gap. The future research directions include, among others, advanced control strategies, grid-forming converters, wideband semiconductor, and cyber-security and Resilience. The paper concludes that the integration of power electronic converters into microgrid technology presents both opportunities and challenges. Although these converters play an important role in the efficient conversion, distribution and utilization of energy in microgrids, they face various technical and practical challenges. To mitigate these challenges, the implementation of advanced control strategies, grid-forming converters, etc., is inevitable.&nbsp