No result found
![Synthesis, Spectroscopic Characterization and Biological Studies Of 2-{[(2-hydroxy-5-nitrophenyl)methylidene]amino} nicotinic acid and Iron (II) complexes](https://www.issuelab.org/resources/36648/custom_cover.png)
2020-04-22
Communication in Physical Sciences;
Iron (II) complexes of 2-{[(2-hydroxy-5nitrophenyl) methylidene]amino} nicotinic acid obtained from o-phenylenediamine and 5nitrosalicaldehyde were prepared and characterized using AAS, UV-Visible, IR, 1HNMR, 13CNMR, and GCMS. The synthesized complex was screened against some microbes in order to establish their potentials antimicrobial activity with reference to some known drugs. The results obtained indicated that, the Schiff base exhibited antimicrobial action against all the tested microbes (except Candidas. albicans isolate, which exhibited zero diameter zone of inhibition) including Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, Enterobacter aeruginosa, and Proteus mirabilis.. It was also found that the synthesized Schiff base exhibited two digits purity range, implying that it was relatively stable. The biological activity of the metal complex of the Schiff base was found to be better than that of synthesized Schiff base.
2020-04-24
Communication in Physical Sciences;
This study analyzed some heavy metals in surface water and sediment from Cross River system in Akwa Ibom State, Nigeria. Water and sediment samples were collected from Ibaka, Oron, Nwaniba, Ayadehe, Okopedi and Enwang and analyzed for the concentration of some heavy metal ions using atomic absorption spectrophotometer. The results obtained from the analysis indicated that mean concentrations of Cd, Pb, Cr, Co, Cu, Se and Ni in surface water were 13.69±8.97, 20.53±10.60, 18±11.47, 25.81±13.91, 26.9±11.0 1.18±0.32 and 32.67±26.16 µg while the corresponding mean concentrations in the sediments were 0.52±0.24, 57.78±15.60, 16.22±5.48, 7.52±2.28, 69.81±16.90, 0.75±0.44 and 6.87±2.26 µg/g, respectively. The results of surface water and sediment quality were compared with some guidelines which revealed no serious contamination risk to man and aquatic organism for surface water and some degree of contamination at some stations for the metals under study in sediment samples
2020-04-29
Communication in Physical Sciences;
Ecological risk assessment of heavy metals at five dumpsites (1 – 5) in Umuahia, Nigeria was carried out. Soil samples were collected at distances of 0, 5 and 10 m from each dumpsite and from a control site. Samples of water leaf and African Spinach leaf were also collected and analysed for heavy metal ions. Soil physicochemical parameters were determined using official and recommended methods while heavy metal ion concentrations were determined using Atomic Absorption Spectrophotometer. Results obtained indicated that the texture of soil samples were predominantly sandy loam while pH values ranged from 6.21±0.37 to 7.70±0.29. Organic matter content ranged from 1.65±0.52 to 4.15±0.36 % while electrical conductivity had a range of 98.47±7.25 – 201.57±15.86 µS/cm across the dumpsites. Mean concentrations of heavy metal ions in soils from the dumpsites were significantly higher (P < 0.05) than those from the control site. Average metal pollution indices showed that soils in the dumpsites are unpolluted except cadmium in Dumpsites 4 and 5. Degree of contamination values showed low degrees of contamination but enrichment factors for Pb, Cd and Cr in some Dumpsites indicated significant enrichments. All dumpsites had geo-accumulation indices less than 1.00 indicating unpolluted soil except Pb and Cr in some Dumpsites which showed moderate pollution. Ecological risk and potential ecological risk indices indicated low ecological risk. Mean concentrations of cadmium ions in the two vegetables from the dumpsites exceeded the Codex maximum limits for Cd in leafy vegetables. Although severe pollution is not pronounced for soils within the study dumpsites, it is recommended that measures should be engaged to control waste disposal in these dumpsites since heavy metals can bioaccumulate and increase in concentration to severe the environmental quality of the dumpsites in the near future.
2020-04-24
Communication in Physical Sciences;
In order to search for local raw materials that could meet the formulation of affordable, nutritious and functional bread that can compete or perform better than the 100% wheat flour, we conducted a study with, composite bread samples baked with blends of wheat, soybeans and plantain flours. The composite flours were formulated using the augmented Simplex Lattice {3,3} design of the response surface methodology (RSM). Fourteen (14) samples from the respective blends were produced using standard method. The bread samples were subjected to sensory evaluation, using the semi-trained panelist of 20 members consisting of 10 male and 10 female, who were familiar with bread quality. The results indicated that the sensory attributes of the 100% wheat (standard) bread, the minimally supplemented bread samples scored higher values of the sensory parameters including shelf stability. Models of the parameters of the bread samples were not significant (p>0.05), but their response surface plots and calculated mathematical models indicated some levels of influence by the components. Optimization analysis of the sensory evaluation and shelf-stability data revealed that 0.590, 0.220, 0.195 proportions of wheat, Musa spp. and soybean flours produced 7.163, 6.835, 6.653, 5.737, 5.301,8.184, for taste, colour, texture, aroma, acceptability and preference respectively at 100% desireability level. Acceptability and preference of the samples exhibited similar trends with the taste, colour, aroma, and texture. The bread quality parameters were observed to be function of the proportions of the flour components in the samples. The mean mold-free day of the samples was 4.0, the highest hedonic value and shelf-stability were observed in the sample that had high substitution of wheat.
2020-05-04
Communication in Physical Sciences;
New Schiff base and its Ni(II) complex, were synthesized using benzaldehyde and sulphathiazole. They were characterized using elemental analyser, UV-visible spectrophotometer, FTIR, 1H-NMR and 13C-NMR spectroscopy. IR spectral data suggested that the ligand coordinated to nickel ions through two azomethine nitrogen, and one amine nitrogen. Electronic spectral measurement indicated the occurrence of ligand to metal charge transfer. Based on the continuous variation method, metal: ligand ratio of 1:1 was proposed. Elemental analysis and spectroscopic studies suggested that the Schiff base behaved as a tridentate ligand towards nickel ion. Antibacterial sensitivity of the ligand and its Ni (II) complex were assayed in vitro against Staphylococcus aureus, Echerichia coli, Pseudomonas aeruginosa and Salmonella typhi. It was observed that the Ni(II) complex was more potent than the Schiff base against the bacterial strains used. Therefore, the Schiff base and its Ni(II) complex may inhibit bacterial infections caused by E.coli, P.aeruginosa, S. typhi and S.aureus. The Ni(II) complex showed enhanced antibacterial activity when compared with the pure the Schiff base.
2020-05-04
Communication in Physical Sciences;
Balanites aegyptiaca (L) Del is a medicinal plant used in Africa's folk medicines to treat wide range of diseases. Phytochemical screening of aqueous and ethanolic extracts of Balanites aegyptiaca (L) Del root indicated the presence of flavonoids, saponins, tannins and phenols.The ethanolic extract of the plant root had in addition carbohydrate, cardiac glycoside and steroids while n-hexane extract indicated the presence of anthraquinone, carbohydrates, cardiac glycoside, terpenoids and resins. The extracts were also evaluated for their free radical scavenging potential, total phenolic and total flavonoid contents. The antioxidant activity was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the total phenolic content was evaluated using Folin-Ciocalteau assay, while the total flavonoid content was assessed by the aluminium chloride colorimetric assay. The results obtained revealed that the ethanolic extract exhibited higher total antioxidant capacity in the range of 55.23±0.4 to 81.04±0.9% while concentrations in the aqueous extract ranged from 20.15±0.2 to 35.11±0.2% compared to 80 % of standard ascorbic acids. Estimated total phenolic content in aqueous and ethanolic extracts were 179.48±1.99 and 260.07±2.31 mg/gallic acid equivalent (GAE)/g respectively. However, the total flavonoid content for aquoues and ethanolic extracts were 69.17±0.32 and 95.52±0.41 mg/ quercetin equivalent (QE)/g respectively. Total phenol and flavonoid were absent in normal hexane extract. The results obtained from the study indicated that the choice of solvent can influence the components that can be extracted from Balanites aegyptiaca (L) Del root and that for optimum extracts to be obtained, the best solvent is ethanol.
2020-04-01
S. D. Bechtel, Jr. Foundation;
Recognizing teachers as the single most important contributor to student achievement, the S. D. Bechtel, Jr. Foundation invests in high-quality models of science teaching and learning in California's K-8 classrooms through full implementation of the California Next Generation Science Standards (NGSS).The S. D. Bechtel, Jr. Foundation envisions children and youth developing the knowledge, skills, and character to explore and understand the world around them, growing into caring, informed, and productive adults. This snapshot, prepared as the Foundation nears conclusion in 2020, documents essential aspects of the Education Program's science portfolio.
2020-07-01
S. D. Bechtel, Jr. Foundation;
With its long-standing commitment to STEM education, the S. D. Bechtel, Jr. Foundation viewed California's 2013 adoption of Next Generation Science Standards (NGSS) as an excellent opportunity to support educators and their students as they transition to these rigorous and engaging standards. This opportunity aligned with the Foundation's overarching emphasis on supporting adult leaders as the most effective way to achieve our goal of providing students with high-quality STEM education.The Foundation launched the six-year NGSS Early Implementers Initiative in 2014. It supports eight diverse California school districts committed to implementing NGSS in their K-8 schools. All districts are incorporating the state's preferred integrated course model for science instruction in middle school. The K-12 Alliance at WestEd, a highly respected provider of professional learning and technical assistance services to school districts, leads the Initiative. Two charter management organizations also participate through funding provided by other sources.The broad goal of the Initiative is to successfully support initial implementation of the science standards in a set of districts to inform state-level decisions and set the stage for statewide implementation. The experiences of the Early Implementers, as well as the tools developed through the Initiative process, are expected to make it easier for other California districts as they implement NGSS. A separate arm of WestEd documents the Early Implementers' approaches, successes, and lessons learned in a series of evaluation reports. The Foundation has invested approximately $25 million in service of this goal.
2020-07-01
WestEd;
As leaders of the teams that implemented and evaluated a six-year statewide effort known as the California NGSS Early Implementers Initiative, the coauthors of this paper have had a front-row seat for implementation of the California NGSS since their adoption in 2013. Coauthor Kathy DiRanna was also strongly involved in the new collaborations formed among science organizations that will be described in this piece. We document this story to attempt to capture the spirit and strategies behind the remarkable collaboration that is bringing forward a new era in state science education practice. We hope this account informs and encourages educational leaders, policymakers, funders, and all who are doing the hard but crucial work of advancing the NGSS and the Common Core.
2020-02-01
S. D. Bechtel, Jr. Foundation;
The California Conservation Fund was a charitable operating foundation established by Stephen D. Bechtel, Jr. to protect and restore waterfowl habitat. The Fund's primary impact was the conservation of more than 4,000 acres of prime habitat. Its secondary impact, while less direct, was larger in scale: Fund activities yielded insight into the underlying dynamics of wetland and open space management in California and, in turn, deeply influenced S. D. Bechtel, Jr. Foundation Environment Program investments. In the Foundation's spend-down years, its Environment Program focused on systemic issues highlighted by the California Conservation Fund's efforts, and worked toward a California that manages, stewards, and conserves its water and land to support a resilient environment and economy.
2020-10-07
Nature;
We report a low noise, broadband, ultrafast Thulium/Holmium co-doped all-fiber chirped pulse amplifier, seeded by an Erbium-fiber system spectrally broadened via coherent supercontinuum generation in an all-normal dispersion photonic crystal fiber. The amplifier supports a − 20 dB bandwidth of more than 300 nm and delivers high quality 66 fs pulses with more than 70 kW peak power directly from the output fiber. The total relative intensity noise (RIN) integrated from 10 Hz to 20 MHz is 0.07%, which to our knowledge is the lowest reported RIN for wideband ultrafast amplifiers operating at 2 µm to date. This is achieved by eliminating noise-sensitive anomalous dispersion nonlinear dynamics from the spectral broadening stage. In addition, we identify the origin of the remaining excess RIN as polarization modulational instability (PMI), and propose a route towards complete elimination of this excess noise. Hence, our work paves the way for a next generation of ultra-low noise frequency combs and ultrashort pulse sources in the 2 µm spectral region that rival or even outperform the excellent noise characteristics of Erbium-fiber technology.
2020-06-01
WestEd;
California counties and school districts are implementing a critically needed change in how they evaluate science instructional materials before investing in local adoption. Past adoptions were often too superficial in nature, focusing on candidate materials' overall look and feel, use of graphical elements, and availability of ancillary materials while insufficiently attending to the substance of the materials for high-quality teaching and learning. In contrast, the California NGSS Toolkit for Instructional Materials Evaluation (hereafter referred to as TIME) process enables participants to use evidence-based measures to choose materials aligned to the Next Generation Science Standards (NGSS) that meet their district's needs.This 11th report in the NGSS Early Implementers Initiative evaluation series is intended for school and district administrators, leaders of science professional learning, and state policymakers. It provides an overview of the full TIME process, including participants' perceptions, a detailed description of the statewide TIME trainings of 2018-19, and a vignette that illustrates a portion of the TIME process.
