Rationalizing the use of mutual prediction models in non-ideal binary mixtures

In this paper, we compared seven diffusion models in terms of prediction performances. Using vapour-liquid equilibrium (VLE) data, we calculate the thermodynamic correction factor as a function of composition for eleven binary liquid mixtures using non-random two-liquid and Redlich-Kister models. These data, together with intra-diffusion coefficients, and viscosity values are used to predict mutual diffusivity. The Darken-based models, which consider a scaling power on the thermodynamic factor, give accurate predictions, with absolute average relative deviation (AARD) values between 1 and 20 %. The removal of the scaling power leads to a decrease in prediction accuracy. The viscosity-based models with (Vis-SF) and without (Vis-nSF) scaling factor have AARD of 14 and 30 %, respectively. The dimerization model is inaccurate for most mixtures except those containing water, while the Vignes-based model (V-Gex), which is based on the Gibbs free energy, gave high AARD values of 25 %, hence, not as reliable when compared to the other models

Adsorption and Kinetic Study of Activated Carbon Produced from Post-Consumer Low-Density Polyethylene (LDPE) Wastes

Post-consumer polymeric wastes in form of low-density polyethylene (LDPE) can now be considered suitable as a precursor for the synthesis of low-cost activated carbon (AC). This study produced AC from LDPE using sulphuric acid (H2SO4) and potassium hydroxide (KOH) as the activating agent. The reaction conditions for pyrolysis were varied in the range of 0.50 - 2.00 M, 400˚C - 500˚C, and 45 - 60 minutes. Physico-chemical investigations revealthat AC yield is significantly dependent on both carbonization temperatures and time. The obtained optimum values of 446.50˚C and 51.09 mins gave a yield of 24% for the base-activated carbon. The high iodine numbers obtained strongly indicate the presence of large surface area and pore volumes is further confirmed using the Scanning Electron Microscopy (SEM) analysis which reveals the presence of pores on the external surface of the carbons. Fourier Transform Infrared Technique (FTIR) analysis further shows that the synthesized compounds are purely carbon with rich oxygen-surface complexes on the surface which is as a result of the introduction of the chemical oxidizing agents. The produced carbons were found to have high adsorption affinity for selected inorganic ions which are: Mn7+, Co2+, and Cr6+. Adsorption isotherm results show the adsorption process to be favourable with the Langmuir isotherm parameter RL having values of <1, while the Freudlich adsorption model was found to perfectly fit the data at selected adsorbent dosages and adsorbate concentrations. The pseudo-second-order model provides the best correlation for the kinetic analysis. The acid-activated carbon was found to have better adsorption capacities than the base-activated carbon

Dental Attendance Among the Elderly in Benin-city, Edo state

Background: Despite the increase in the elderly population globally, it appears that several studies focused on dental clinic attendance by other age groups and with sparse data on the elderly. Aim: This study therefore, aimed to determine the rate of dental clinic attendance among the elderly in Benin-city. Materials and methods: This was a half year multi-center, prospective cross-sectional study. This study conducted among dental patients at the outpatient departments two tertiary health facilities in Benin-city.  A three-sectioned questionnaire was used to collect data. The data collected were sex, age, and level of educational, marital status, occupational level, religion, and ethnicity. Other collected data were co-morbidities, previous visit to dental clinic, time of   last visit, reason for last visit, intention to visit the clinic again, presenting complaints and barriers to dental attendant.  Both descriptive and inferential statistics were analyzed. Results: a total number of patients seen were 1450. The prevalence of the elderly patients was 27.7 %. Mean age was 70.4 ± 5.7 years with age range of 65- 97 years. The female elderly were more (52.9%) than their male counterparts. More than half (53.6%) had hypertensions. Less than half (30.2%) rate their dental health as good. More than half (56.9%) have never visited the dental clinic.  Of all the presenting complained asked of the respondents, highest (18.5%) proportion was for toothache. Majority (71.3%) of the respondents affirmed that cost of transportation and long distance was the barrier for attending dental clinic. The rate of attendance (χ = 8.9; p = 0.03) and time of last visit (T =2.84; p = 0.01) was affected by the age of the respondents Conclusions: There was poor attendance to dental clinic by elderly in Benin City mainly due to cost of transportation and long distance. Age was related to poor attendance and time of visitation for attendance. Key words: Dental clinic, attendance, elderl

Acquisition, maintenance and adaptation of invasion inhibitory antibodies against Plasmodium falciparum invasion ligands involved in immune evasion

Erythrocyte-binding antigens (EBAs) and P. falciparum reticulocyte-binding homologue proteins (PfRhs) are two important protein families that can vary in expression and utilization by P. falciparum to evade inhibitory antibodies. We evaluated antibodies at repeated time-points among individuals living in an endemic region in Nigeria over almost one year against these vaccine candidates. Antibody levels against EBA140, EBA175, EBA181, PfRh2, PfRh4, and MSP2, were measured by ELISA. We also used parasites with disrupted EBA140, EBA175 and EBA181 genes to show that all these were targets of invasion inhibitory antibodies. However, antigenic targets of inhibitory antibodies were not stable and changed substantially over time in most individuals, independent of age. Antibodies levels measured by ELISA also varied within and between individuals over time and the antibodies against EBA181, PfRh2 and MSP2 declined more rapidly in younger individuals (15 years) compared with older (>15). The breadth of high antibody responses over time was more influenced by age than by the frequency of infection. High antibody levels were associated with a more stable invasion inhibitory response, which could indicate that during the long process of formation of immunity, many changes not only in levels but also in functional responses are needed. This is an important finding in understanding natural immunity against malaria, which is essential for making an efficacious vaccine

Longitudinal invasion inhibitory activity profiles of representative individuals.

<p>Individuals exhibited diverse invasion inhibitory activity against the 3D7 WT relative to the EBA knockout parasites overtime. Individual AD23 inhibited the EBA knockout parasites more than the parental parasite; individual AD50 inhibited the parental parasite more than the EBA knockout parasite lines.</p

Kaplan- Meier survival curves showing the proportion of individuals with antibody levels of >50% of the day 0 antibody level for all antigens among the different age groups and among individuals with different levels of exposure to <i>P</i>. <i>falciparum</i>.

<p>Kaplan- Meier survival curves showing the proportion of individuals with antibody levels of >50% of the day 0 antibody level for all antigens among the different age groups and among individuals with different levels of exposure to <i>P</i>. <i>falciparum</i>.</p

Relationship between invasion inhibitory antibodies to invasion pathway ligands parasitaemia and age.

<p>(A) Effects of antibodies directed against SA-dependent or SA-independent pathways on the mean parasitaemia. “<b>A</b>”, “<b>B</b>” represent individuals with only antibody responses to SA-dependent or SA-independent pathway invasion ligands, respectively. “<b>A and B”</b> represents individuals that presented a response to both pathways. (B) Effect of age on the acquisition of antibody responses to the two invasion pathways.</p

Comparison of EBA175 and PfRh2 antibody levels between individuals that switched between invasion inhibition patterns and those with unchanging invasion patterns.

<p>Bars represent the mean antibody levels and SEM. ‘‘Switchers” represents individuals that had fluctuating invasion inhibitory patterns while ‘‘Non-switchers” represents those that had stable invasion inhibitory pattern.</p

Seasonal variation in overall differential inhibition of 3D7 WT and the knockout lines.

<p>There were no differences between the overall inhibition between the 3D7 WT and EBA knockout parasites through the seasons except for EBA175 knockout parasites in the months of July, October, and January. Values represent mean of all samples ± SEM.</p