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Are standard tests sensitive enough to evaluate effects of human pharmaceuticals in aquatic biota? Facing changes in research approaches when performing risk assessment of drugs

Sun, 01 Feb 2015 00:00:00 GMT

Title: Are standard tests sensitive enough to evaluate effects of human pharmaceuticals in aquatic biota? Facing changes in research approaches when performing risk assessment of drugs Authors: Aguirre-Martínez, G. V.; Owuor, Margaret A.; Garrido-Pérez, C.; Salamanca, M. J.; Del Valls, T. A.; Martín-Díaz, M. L. Abstract: Nowadays, the presence of pharmaceutical products in aquatic environments is not only common, but is also of significant concern regarding the adverse effect they may produce to aquatic biota. In order to determine the adverse effects of caffeine (CAF), ibuprofen (IBU), carbamazepine (CBZ) and novobiocin (NOV), at environmental occurring concentrations, standardized endpoints applied in current guidelines were evaluated in four organisms including bioluminescence response in Vibrio fischeri, growth inhibition in Isochrysis galbana (marine water) and Pseudokirchneriella subcapitata (fresh water) and fertilization and embryo-larval development in Paracentrotus lividus. To reach this aim bioassays were implemented by exposing organisms to water spiked with drugs dissolved in DMSO (0.001% v/v). Risk characterization was performed, calculating the environmental impact of drugs by calculating environmental concentration and predicted no effect concentration ratio (MEC/PNEC). Results indicate that acute toxicity was found above environmental concentrations in the order of mg L−1 for bacteria bioluminescence, microalgae growth inhibition and sea urchin fertilization. However, teratogenicity was observed on sea urchin after exposure to environmental concentrations of drugs at 0.00001 mg L−1; at this concentration CBZ and IBU were found to reduce significantly the embryo-larval development compared to controls (p < 0.01). The risk calculated for selected drugs suggested they are harmless for aquatic environment except when applying the embryo-larval development endpoint. Endpoints applied in this study showed the necessity of using more sensitive responses, when assessing risk of pharmaceuticals in aquatic environments, since endpoints applied in current guidelines may not be suitable. Description: https://doi.org/10.1016/j.chemosphere.2014.05.087

Knowledge management strategy and academic performance of public day secondary schools in Matungu Sub-County, Kenya

Sun, 01 Jun 2025 00:00:00 GMT

Title: Knowledge management strategy and academic performance of public day secondary schools in Matungu Sub-County, Kenya Authors: Ndakalu, Kayugira O.; Yatundu, Faraji A.; Wanyama, Kadian Abstract: Past research with regard to human resource management strategies against academic performance gave little attention on how knowledge management affect academic performance. This study examined the relationship between knowledgemanagement strategies and academic performance of public day secondary schools in Matungu Sub- County of Kakamega County in Kenya. The study was anchored on Behavioral Perspective Theory. The study used descriptive research design with a target population of 20 principals and 388 teachers totaling 408 respondents. The respondents were drawn from 20 public day secondary schools in Matungu SubCounty of Kakamega County. Purposive and stratified sampling method was used. Yamane formula was used to calculate the sample size of 201 respondents. Primary data was obtained using a structured questionnaire pretested for reliability and validity. For reliability analysis Cronbach’s alpha was used. Pilot study was carried out at Madende Mixed day secondary school in Busia County. The period of the study covered was five years from 2017 to 2022. The data collected was analyzed quantitatively in relation to research objectives. Descriptive statistics was employed which consisted of frequency tables, percentage, standard deviation and weighted mean. Trend analysis was then applied to predict the research variables and then finally data was presented using tables. Knowledge management had a positive and statistically significant relationship with Academic Performance (Knowledge Management (B = 0.142, Beta = 0.160, p = 0.008). On recommendations,Knowledge management boosts academic performance in public day secondary schools,encourage collaboration between policymakers, practitioners, and academics to ensure that research informs policy and practice, and vice versa.But gaps exist in aligning training outcomes with organizational objectives and understanding individual impact on success Description: DOI: 10.35629/3002-13065667

Localized surface plasmon resonance and damping mechanisms in transition metals

Mon, 23 Mar 2026 00:00:00 GMT

Title: Localized surface plasmon resonance and damping mechanisms in transition metals Authors: Sila, Faith; Mbaluka, Benjamin; Riara, Martin M.; Katumo, Ngei Abstract: This work reports the calculated dependence of the localized surface plasmon resonance (LSPR) parameters and damping mechanism on nanoparticle size of unconventional transition metals, including zinc, silver, rhodium, rhenium, molybdenum, tantalum, titanium, and scandium, within the size range of 10 to 400 nm. The study applies Mie theory to determine the peak energies, amplitude, and full width at half maximum (FWHM) of LSPR as a function of size, shape, and material type. We have found that the parameters of LSPR depend on electron structure and damping mechanisms. LSPR amplitude decreased systematically for individual nanoparticles (NPs) for sizes 10…200 nm, after which, a similar trend was exhibited due to radiative damping. Au, Sc and Ag are the only metal NPs that exhibited a significant FWHM of LSPR at sizes approximately below 40 nm. For all investigated transition metal NPs, smaller NPs exhibited higher absorption and lower scattering, while larger NPs showed narrower FWHM and red-shifted LSPR peaks due to retardation effects and multipolar plasmon excitations. The analysis highlights that some transition metal NPs exhibit optical characteristics similar to those of gold, silver, and copper, making them a good alternative for the mentioned ones at specific NP sizes. Description: DOI: https://doi.org/10.15407/spqeo29.01.051

Genetic analysis of walnut cultivars from southwest China: Implications for germplasm improvement

Tue, 01 Nov 2022 00:00:00 GMT

Title: Genetic analysis of walnut cultivars from southwest China: Implications for germplasm improvement Authors: Wambulwa, Moses C.; Fan, Peng-Zhen; Milne, Richard; Wu, Zeng-Yuan; Luo, Ya-Huang; Wang, Yue-Hua; Gao, Lian-Ming; Xiahou, Zuo-Ying; Jin, Ye-Chuan; Ye, Lin-Jiang; Xu, Zu-Chang; Yang, Zhi-Chun; Li, De-Zhu; Liu, Jie Abstract: Walnuts are highly valued for their rich nutritional profile and wide medicinal applications. This demand has led to the intensification of breeding activities in major walnut production areas such as southwest China, in order to develop more superior cultivars. With the increasing number of cultivars, accurate identification becomes fundamental to selecting the right cultivar for grafting, industrial processing or development of new cultivars. To ensure proper identification of cultivars and understand the genetic structure of wild and cultivated material, we genotyped 362 cultivated and wild individuals of walnut trees from southwest China (with two additional populations from Xinjiang, plus three cultivars from Canada, France and Belgium) using 36 polymorphic microsatellite loci. We found relatively low indices of genetic diversity (HO = 0.570, HE = 0.404, NA = 2.345) as well as a high level of clonality (>85% of cultivars), indicating reliance on genetically narrow sources of parental material for breeding. Our STRUCTURE and PCoA analyses generally delineated the two species, though considerable levels of introgression were also evident. More significantly, we detected a distinct genetic group of cultivated Juglans sigillata, which mainly comprised individuals of the popular ‘Yangbidapao’ landrace. Finally, a core set of 18 SSR loci was selected, which was capable of identifying 32 cultivars. In a nutshell, our results call for more utilization of genetically disparate material, including wild walnut trees, as parental sources to breed for more cultivars. The data reported herein will significantly contribute towards the genetic improvement and conservation of the walnut germplasm in southwest China. Description: https://doi.org/10.1016/j.pld.2021.08.005