Prediction of Rockfill Materials’ Shear Strength Using Various Kernel Function-Based Regression Models—A Comparative Perspective

The mechanical behavior of the rockfill materials (RFMs) used in a dam’s shell must be evaluated for the safe and cost-effective design of embankment dams. However, the characterization of RFMs with specific reference to shear strength is challenging and costly, as the materials may contain particles larger than 500 mm in diameter. This study explores the potential of various kernel function-based Gaussian process regression (GPR) models to predict the shear strength of RFMs. A total of 165 datasets compiled from the literature were selected to train and test the proposed models. Comparing the developed models based on the GPR method shows that the superlative model was the Pearson universal kernel (PUK) model with an R-squared (R²) of 0.9806, a correlation coefficient (r) of 0.9903, a mean absolute error (MAE) of 0.0646 MPa, a root mean square error (RMSE) of 0.0965 MPa, a relative absolute error (RAE) of 13.0776%, and a root relative squared error (RRSE) of 14.6311% in the training phase, while it performed equally well in the testing phase, with R² = 0.9455, r = 0.9724, MAE = 0.1048 MPa, RMSE = 0.1443 MPa, RAE = 21.8554%, and RRSE = 23.6865%. The prediction results of the GPR-PUK model are found to be more accurate and are in good agreement with the actual shear strength of RFMs, thus verifying the feasibility and effectiveness of the model.     

Colour Change of Sustainable Concrete Containing Waste Ceramic and Hybrid Fibre: Effect of Temperature

Construction and demolition (C&D) waste was considered as zero value materials and, as a result, most C&D waste materials ended up in landfills, eventually constituting environmental issues. Therefore, it is important to explore the potential of such C&D waste materials for concrete production. Thus, this research effort aims to find a new method to improve sustainable concrete properties exposed to elevated temperatures at the lowest costs and identify the relationship between temperature change and a change in colour in a heat-exposed concrete structure. Therefore, this study explored the behaviour of three types of concrete: plain concrete (PC), waste ceramic optimal concrete (WOC), and waste ceramic optimal concrete reinforced by hybrid fibre (WOC-Hybrid) in ambient and elevated temperature. The study shows that colour change in a concrete structure exposed to high temperature has a consistent relationship, where it has been found that the colour alteration is of great interest because its appearance usually coincides with the onset of a significant loss of concrete strength as a result of elected temperatures. Overall, it can be considered that waste ceramic materials reinforced by hybrid fibres can be used for concrete production, and by doing so, the negative impact of these wastes on the environment can be controlled as well as fortify the mechanical properties.     

Biological Effects of Pyrimethinal on Aquatic Worms (Tubifex tubifex) Under Laboratory Conditions

Laboratory studies were conducted to determine the effects of different concentrations of pyrimethinal on protein contents, and some oxidative stress in Tubifex tubifex after an exposure of 2, 4, and 7 days. Residues of the fungicide were followed in water and in the worms. In water, pyrimethinal concentration decreased slowly (maximum ?6.4 % ± 0.8 % after 2 days for 25 mg L^?1). In the worms, it increased after 4 days and decreased thereafter. LC₅₀ values were between 49.2 ± 0.58 and 39.5 ± 0.95 mg L^?1 depending on exposure time. The activity of catalase increased in response to the fungicide after 2 days of exposure to 25 mg L^?1 of pyrimethinal (+90 %). The highest decrease of glutathione-S-transferase activity (?29.7 %) was found after 7 days in the presence of 25 mg L^?1.     

Effect of exposure to perfluorooctanoic acid on hepatic antioxidants in mice

The present study was undertaken to evaluate hepatic antioxidants status in female mice after exposure to perfluorooctanoic acid (PFOA). A total number of 20 female mice were subjected to the study; out of them, 15 mice were treated with PFOA. PFOA solutions were prepared at 0.1, 0.5, and 1?mg/ml of deionized water and administered to the mice by gavage once daily for 3?weeks at a volume of 10?ml/kg. Controls (five mice) received an equivalent volume of deionized water. The results revealed significant increase in liver weight at dose of 5 (p?<?0.01) and 10?mg/kg body weight (b.w., p?<?0.01). Both hepatic total glutathione level and hepatic catalase activity were significantly increased (p?<?0.01) at dose of 5?mg/kg b.w. On the other hand, hepatic glutathione reductase activity was significantly increased at dose of 10?mg/kg b.w. In this model system, PFOA administration was effective in inducing oxidative stress particularly reflected in the liver.     

Norchloro-fluoro-homoepibatidine (NCFHEB) - a promising radioligand for neuroimaging nicotinic acetylcholine receptors with PET.

Cholinergic neurotransmission depends on the integrity of nicotinic acetylcholine receptors (nAChRs), and impairment of both is characteristic for various neurodegenerative diseases. Visualization of specific receptor subtypes by positron emission tomography (PET) has potential to assist with diagnosis of such neurodegenerative diseases and with design of suitable therapeutic approaches. The goal of our study was to evaluate in vivo the potential of (18)F-labelled (+)- and (-)-norchloro-fluoro-homoepibatidine ([(18)F]NCFHEB) in comparison to 2-[(18)F]F-A-85380 as PET tracers. In the brains of NMRI mice, highest levels of radioactivity were detected at 20 min post-injection of (+)-[(18)F]NCFHEB, (-)-[(18)F]NCFHEB, and 2-F-[(18)F]-A-85380 (7.45, 5.60, and 3.2% ID/g tissue, respectively). No marked pharmacological adverse effects were observed at 25 mug NCFHEB/kg. Uptake studies in RBE4 cells and in situ perfusion studies suggest an interaction of epibatidine and NCFHEB with the carrier-mediated choline transport at the blood-brain barrier. The data indicate that (+)- and (-)-[(18)F]NCFHEB have potential for further development as PET tracers.     

Mitochondrial-mediated apoptosis in neural stem cells exposed to manganese.

Manganese is an essential nutrient for humans that has to be maintained at proper levels for normal brain functioning. However, manganese also acts as a toxicant to the brain, and several studies have linked exposure to excessive manganese to neurotoxicity in adults. A recent report has suggested that ingesting high doses of manganese via drinking water can impede intellectual functions in children. It is known that during development, the nervous system is particularly vulnerable to different types of injuries and toxicants. Neural stem cells (NSCs) play an essential role in both the developing nervous system and the adult brain where the capacity for self-renewal may be important. In the present study, we have used NSCs to investigate the molecular mechanisms involved in manganese developmental neurotoxicity. The results show that primary cultures of rat embryonic cortical NSCs as well as the murine-derived multipotent NSC line C17.2 undergo apoptotic cell death via a mitochondrial-mediated pathway in response to manganese. Exposed cells exhibit typical apoptotic features, such as chromatin condensation and cell shrinkage, mitochondrial cytochrome c release, activation of caspase-3, and caspase-specific cleavage of the endogenous substrate poly (ADP-ribose) polymerase. In addition, our data also show that reactive oxygen species formation plays a role in the onset of manganese toxicity in NSCs.     

Prognostic significance of hypernatremia and hyponatremia among patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE: Abnormal serum sodium levels (hyponatremia and hypernatremia) are frequently observed during the acute period after aneurysmal subarachnoid hemorrhage (SAH) and may worsen cerebral edema and mass effect. We performed this study to determine the prognostic significance of serum sodium concentration abnormalities. METHODS: We analyzed prospectively collected data for the placebo treatment group in a clinical trial conducted at 54 neurosurgical centers in North America. The presence of hypernatremia (serum sodium concentration of >145 mmol/L) and hyponatremia (serum sodium concentration of <135 mmol/L) was determined with serum sodium measurements obtained at admission and 3, 6, and 9 days after SAH. The effects of hypernatremia and hyponatremia on the risk of symptomatic vasospasm and on 3-month outcomes were analyzed after adjustment for the following potential confounding factors: age, sex, preexisting hypertension, admission Glasgow Coma Scale score, initial mean arterial pressure, subarachnoid clot thickness, intraventricular blood or intraparenchymal hematoma, ventricular dilation, and aneurysm size and location. RESULTS: Of 298 patients in the analysis, 58 (19%) developed hypernatremia and 88 (30%) developed hyponatremia. Hypernatremia was significantly associated with poor outcomes (odds ratio, 2.7; 95% confidence interval, 1.2-6.1). A positive correlation was observed between the highest sodium values recorded and Glasgow Outcome Scale scores at 3 months (P < 0.0001 by analysis of variance). Hyponatremia was not associated with 3-month outcomes (odds ratio, 1.9; 95% confidence interval, 0.9-4.3). Neither hypernatremia nor hyponatremia was associated with the risk of symptomatic vasospasm. CONCLUSION: Hyponatremia seems to be more common than hypernatremia after SAH. However, hypernatremia after SAH is independently associated with poor outcomes, and this association is independent of previously identified outcome predictors, including age and admission Glasgow Coma Scale scores. Further studies are needed to define the underlying mechanism of this association.