Shear Thickening and Scaling of the Elastic Modulus in a Fractal Colloidal System with Attractive Interactions

Dilute oil dispersions of fractal carbon black particles with attractive Van der Waals interactions display continuous shear thickening followed by shear thinning at high shear rates. The shear thickening transition occurs at $\dot\gamma_{c}\approx 10^{2}-10^{3}s^{-1}$ and is driven by hydrodynamic breakup of clusters. Pre-shearing dispersions at shear rates $\dot\gamma>\dot\gamma_{c}$ produces enhanced-modulus gels where $G' \sim \sigma_{pre-shear}^{1.5-2}$ and is directly proportional to the residual stress in the gel measured at a fixed sample age. The observed data can be accounted for using a simple scaling model for the breakup of fractal clusters under shear stress.Comment: 5 pages, 5 figures; v2: treating low shear rate date separately; edited title; reworked figure

Comparison Of Canonical Correlation Analysis And The Generalized Canonical Correlation Analysis Using The Lognormal And Cauchy Distributed Data

This work compares the Canonical Correlation Analysis and Generalized Canonical Correlation Analysis for two data sets using Lognormal and Cauchy distributions. Data of different sample sizes (10, 20, 30, 40 and 50) were simulated and used to perform the analysis. Their relative efficiencies were calculated and it was discovered to be the same for two data sets except for scaling. Keywords: Relative efficiency, Scaling, Canonical Correlation Analysis, Generalized Canonical Correlation Analysis, Lognormal, Cauch

How Careers Advice and Guidance can Facilitate Career Development in TVET Graduates: The case in Nigeria

This study examined the current state of careers advice, guidance, and counselling (CAGC) services and programs in the technical, vocational education, and training (TVET) system of Nigerian higher education institutions (HEIs). This was to determine how well current CAGC services and programs foster students’ career development, aspirations, and choices. Forty-eight participants, who were members of the Nigerian National Board for Technical Education (8 participants), guidance counsellors (6), university TVET teachers (18), career experts from the National Directorate of Employment (7), and newly employed TVET graduates (9), volunteered for the study. A purposeful sampling procedure was adopted to recruit participants. Data were collected using a semi-structured interview approach, and we employed a thematic design for the coding and analysis of the transcribed data. The study found no CAGC services and programs in the TVET system. It is recommended, therefore, that TVET systems should focus on providing career development enhanced learning rather than schooling only by revising the curriculum to include programs and activities that promote CAGC activities and programs

Post Partum Hemorrhage in Delta State, Nigeria; A Logistic Approach

Postpartum Hemorrhage (PPH) is a leading cause of maternal morbidity and mortality relating to pregnancy especially in less developed and developing countries, as it accounts for about 44,000 - 60,000 death yearly. This study is designed to extract the risk factor(s) associated with PPH.

Study of the Effects of Thermal Annealing on the Optical Band Gap of Nanocrystalline CoO Thin Films Prepared by Chemical Bath Deposition.

Nanocrystalline films of cobalt oxide have been prepared on glass slides by chemical bath deposition process. For deposition of CoO thin films, cobaltous chloride [CoCl2.6H2O] was used as cationic and ammonia [NH3] as anionic precursor in aqueous medium. In this process NaOH was used as complexing agent. X-ray diffraction, scanning electron microscopic [SEM] analysis have been used to study the films’ crystal structures, optical and solid state properties. We hereby present the effects of thermal annealing on the optical band gap of CoO thin films. The optical transition in the films is direct one. For the as- deposited film, the band gap is 2.1eV. This later decreased to 2.08eV, so that increased thermal annealing reduces the optical band gap of CoO. However,the energy gap cannot be said to be dependent on the annealing temperatures. These films could be used as  photovoltaic cells, sensors light emitting diodes and also in biomedical imaging. Key Words: Nanocrystalline CoO, Chemical Bath Deposition, Band Gap and                               Thermal Annealing

Sustainability of Climate Change Adaptation Measures in South-South, Nigeria

The rampaging effects of climate change on Nigeria agriculture cannot be totally undermined, hence, the sustainability of climate change adaptation measures in South-South, Nigeria. A multi-stage sampling technique was used to select 142 farmers who were interviewed to elicit information bordering on climate change in the area. Data were analyzed using descriptive statistics, ordinary least square multiple regression technique and the scaling model. Results showed that the socio-economic factors investigated influenced the decisiveness of the farmers in embracing adaptive strategies to checkmate the overindulgence of climatic variations in the area. Age of the farmers, educational level, household size, farming experience, farm size, extension contacts were all positive and significant factors. Result also shows that there is increasing rate of temperature, rainfall volume, sunshine hours and number of rainy days and decreasing rate of light intensity and wind. The adaptation techniques of the farmers were classified into highly sustainable adaptation strategies which include; use of pest and disease resistant varieties, use of organic fertilizers, tree planting, early information seeking on climate change etc and slightly sustainable; planting of different crop varieties, mulching, mixed cropping, etc. All the farmers in the area perceived inadequate capital as a major constraint in coping with climate change effects. Hence, this study recommends government all levels to sensitize the crop farmers on the devastating effects of climate change on agriculture as well as provide supports where necessary to cushion its negative impacts

Oscillatory Shear Flow-Induced Alignment of Lamellar Melts of Hydrogen-Bonded Comb Copolymer Supramolecules

In this work we present the orientational behavior of comb copolymer-like supramolecules P4VP(PDP)1.0, obtained by hydrogen bonding between poly(4-vinylpyridine) and pentadecylphenol, during large-amplitude oscillatory shear flow experiments over a broad range of frequencies (0.001-10 Hz). The alignment diagram, presenting the macroscopic alignment in T/TODT vs ω/ωc, contains three regions of parallel alignment separated by a region of perpendicular alignment. For our material, the order-disorder temperature TODT = 67 °C and ωc, the frequency above which the distortion of the chain conformation dominates the materials’ viscoelasticity, is around 0.1 Hz at 61 °C. For the first time flipping from a pure transverse alignment via biaxial transverse/perpendicular alignment to a perpendicular alignment as a function of the strain amplitude was found.

The possible role of local air pollution in climate change in West Africa

The climate of West Africa is characterized by a sensitive monsoon system that is associated with marked natural precipitation variability. This region has been and is projected to be subject to substantial global and regional-scale changes including greenhouse-gas-induced warming and sea-level rise, land-use and land-cover change, and substantial biomass burning. We argue that more attention should be paid to rapidly increasing air pollution over the explosively growing cities of West Africa, as experiences from other regions suggest that this can alter regional climate through the influences of aerosols on clouds and radiation, and will also affect human health and food security. We need better observations and models to quantify the magnitude and characteristics of these impacts