Soil slaking sensitivity as influenced by soil properties in alluvial and residual humid tropical soils

Purpose: In the humid Caribbean region characterized by high intensity tropical rainfall, soil aggregate breakdown and pore blocking due to slaking pressures are major land degradation mechanisms. In this research, we investigated the susceptibility of soils to slaking pressures under rapid wetting as influenced by soil properties and the depositional origin from which the soil is formed using water stable aggregates (WSAr) and percolation stability (PSc) as indices of the strength of aggregate inter-particle cohesion. Materials and methods: Wet sieving and percolation stability analyses were employed to investigate WSAr and pore blocking, respectively. The combined effect of soil properties of clay, organic matter (OM), cation exchange capacity (CEC) and exchangeable sodium percentage (ESP) was used to determine the slaking sensitivity score (SSc) of fourteen physiogeographically important soils in Trinidad, comprising of nine alluvial and five residual soils. Results and discussion: Results showed that irrespective of alluvial or residual depositional nature of the parent material, samples had high SSc with an average WSAr of 37.8% and PSc of 6.0mm/10 minutes. The linear relationships between SSc with WSAr (r2 = -0.12) and SSc with PSc (r2 = -0.012) of all the 14 soils although negative were weak. Clay content accounted for 94.0% of the variation in CEC in alluvial soils and had a strong negative relationships with WSAr (r2 = -0.74) and PSc (r2 = -0.79) in residual soils. Additionally, OM with WSAr (r2 = 0.52) and PSc (r2 = 0.24), and CEC with WSAr (r2 = 0.46) and PSc (r2 = 0.39) showed significant positive linear relationships in residual soil. Conclusions: The predominantly micaceous and kaolinitic clay mineralogy of these soils coupled with the low OM contents, increase the proneness of the soils to slaking. This suggests that clay mineralogy is responsible for the high slaking sensitivity rather than clay content or just the depositional origin of the soils. As CEC increases, an accompanying increase in OM is required to increase inter-particle cohesion and to impart partial hydrophobicity, which in turn decreases mineralogically induced susceptibility of individual aggregates to slaking

Phytochemical analysis and antioxidant activity of methanolic extract of <i style="mso-bidi-font-style:normal">Plectranthus hadiensis </i>(Forssk.) Schweinf. ex Spreng. aerial parts

359-365Herbal medicine has been in use by diverse civilizations in different parts of the world for centuries. Present study investigates the phytochemical constitution of the methanolic extract of the aerial part of Plectranthus hadiensis (Forssk.) Schweinf. ex Spreng. The preliminary phytochemical screening of the methanolic extract had revealed high content of phenolics which was confirmed by TLC, HPTLC and HPLC studies. The antioxidant activity was checked using DPPH assay, nitric oxide radical scavenging activity assay and reducing power assay. The methanolic extract showed considerably high antioxidant activity compared to the standards used, viz. ascorbic acid and BHT (Butylated Hydroxy Toluene). The presence of phenolics supported medicinal uses of the species and active biomolecules could be isolated for pharmaceutical applications

EEG Patterns in Patients With Calcified Neurocysticercosis With or Without Hippocampal Atrophy

Purpose: To assess whether hippocampal atrophy develops in conjunction with clinical or subclinical epileptiform or encephalopathic activity in subjects with neurocysticercosis (NCC). Methods: Using a population-based and nested case control study design, scalp EEGs and brain MRIs were performed in Atahualpa residents aged >= 40 years, who have imaging confirmed NCC (case patients), as well as in age- and sex-matched NCC-free control subjects. Results: Sixty-two case patients and 62 control subjects were included. Encephalopathic EEG patterns were more common in five NCC subjects with epilepsy than in those without a history of seizures. Epileptiform EEG activity was noted in one patient with NCC but in none of the control subjects. This subject's focal epileptiform discharges correlated with the location of calcified cysticerci in the brain parenchyma, and the hippocampus ipsilateral to the epileptiform discharges was more atrophic than the contralateral hippocampus. The degree of hippocampal atrophy in patients with NCC without a history of seizures was significantly greater than in control subjects (P < 0.01) and tended to be even greater in patients with NCC with a history of seizures. Conclusions: Hippocampal atrophy may not be exclusively related to seizure activity in patients with NCC. Other mechanisms, such as recurrent bouts of inflammation around calcified cysticerci, might explain the association between NCC and hippocampal atrophy

Calcified Neurocysticercosis and Headache in an Endemic Village: A Case-Control Study Nested to a Population-Based Cohort

Headache in patients with calcified neurocysticercosis (NCC) is probably common but has been largely overlooked. We aimed to assess the presence, characteristics, and diagnosis of headache across patients with calcified NCC and their matched controls. In this case-control study nested to a population-based cohort, Atahualpa residents aged (3) 20 years with calcified NCC were identified as case patients and paired 1: 1 to age-and gender-matched randomly selected controls. A culturally adapted questionnaire was derived from the EUROLIGHT. Headache diagnosis was established according to the International Classification of Headache Disorders, 3rd edition. Conditional logistic regression models for matched paired data were fitted to assess the independent association between calcifiedNCC(as the exposure) and headache variables, after adjusting for education, alcohol intake, depression, and epilepsy. The selection process generated 106 case patients and their matched controls. Lifetime headache prevalence (odds ratio [OR]: 4.18; 95% Confidence Interval [CI]: 1.79-9.75; P = 0.001), current headaches (OR: 4.19; 95% CI: 1.92-9.16; P < 0.001), and intense headaches (OR: 9.47; 95% CI: 2.88-31.19; P < 0.001) were more frequent among cases than in controls. In addition, migraine (but not other forms of headache) was more frequent among subjects with calcified NCC (OR: 4.89; 95% CI: 2.36-11.39; P < 0.001). This study shows a robust epidemiological association between headache-particularly migraine-and calcified NCC