A study of the viscometric and volumetric properties of some multi-component liquid regular solutions at different temperatures.

The densities and kinematic viscosities of the quinary liquid regular system octane(1)-hexane(2)-ethylbenzene(3)-cyclohexane(4)-toluene(5) and two of its quaternary subsystems were measured at 293.15 K and 298.15 K. In addition, the densities and kinematic viscosities of the quinary liquid regular system octane(1)-heptane(2)-ethylbenzene(3)-cyclohexane(4)-toluene(5) and all of its quaternary and ternary subsystems were measured at the same two temperatures. The data collected in the present study were employed in testing the predictive capabilities of some of the most widely used viscosity models for liquid mixtures. Comparison of the predictive capabilities of the various literature models showed indicated that the generalized McAllister three-body collision model gave the lowest deviation from the experimental results.Dept. of Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .E443. Source: Masters Abstracts International, Volume: 43-01, page: 0257. Adviser: Abdul-Fattah A. Asfour. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Introducing a New Technology for Seawater Treatment With Solar Energy

Solar desalination has been used for long time to obtain potable water from seawater, but because of a number of technical difficulties, the technique has not been commercialized to serve industrial-scale or large communities demand of water. With the current trend of population increase in the world (and in South-East Asia in particular), affordable water desalination techniques will be highly required, as most current techniques, including those using distillation or membranes, have high initial and running costs. The technique suggested here will significantly reduce the running cost of water desalination units. With a simple distillation process requiring only solar energy to evaporate the water, this technique will introduce, for the first time, a practical way to desalinate seawater at a significantly low running cost. Successful implementation of this technique will be of good value to the economies of countries are exposed to sunshine for long hours per day or year, most valuable incorporation of this technique is expected to be in countries of the equatorial region having long coasts

Effects of Cyclodextrins on the Kinetics of Emulsion Polymerisation

Cyclodextrins (CD) are semi-natural oligosaccharides composed of a number of D-glucose units. They are produced from renewable resources, and have been found to be of catalytic effect for the emulsion polymerization of many monomers. Using monomers whose emulsion polymerization kinetics have been thoroughly studied, this research analyses the effect of CD on the entry and exit rate coefficients for the emulsion polymerization of styrene, and the entry and termination rate coefficients for the emulsion polymerization of MMA. Throughout the course of the work, CD was found to have a positive impact on the polymerization rate of styrene in a polystyrene latex stabilized with a cationic surfactant. Furthermore, the exit rate coefficient for this latex was found, via γ-relaxation experiments, to increase in proportion to the styrene solubility in water, exactly as predicted by theory. Of itself this would lead to a decrease in reaction rate. That there is still an overall increase in the reaction rate in the presence of CD is because of a quite strong effect on entry rate coefficients. Again, this is consistent with the prevailing theory for entry, that of Maxwell and Morrison, which says that increased aqueous phase solubility of monomer will lead to faster entry. Intriguingly, experiments done on a polystyrene latex stabilized with an anionic surfactant showed a different effect for CD: γ-relaxation experiments found very little effect of CD on exit rate, and chemically initiated experiments found the same for overall rate. This is consistent with CD having little effect on aqueous phase styrene solubility, which in fact is what direct measurements via UV-visible spectroscopy indicated. It is speculated that the anionic surfactant was successfully competing with styrene to occupy the CD cavities. On the other hand, measurements suggested that styrene successfully competes with cationic surfactant, which is consistent with kinetic results. Experiments of the above nature were then carried out with methyl methacrylate (MMA), a more water soluble monomer than styrene and one with emulsion polymerisation kinetics of a different nature (so-called pseudo-bulk). γ-relaxation experiments found no effect of CD on termination rate coefficients, exactly as one would expect given that termination is an intra-particle reaction whereas CD exists in the aqueous phase. However the same experiments also revealed an unexpected effect of CD on entry: the thermal entry rate coefficient was found to increase markedly in the presence of CD. It seems likely that this unusual effect stems from interaction of products of γ radiolysis with CD. Results for chemically-initiated polymerization of MMA were inconclusive. Under some conditions there was actually retardation in the presence of CD, which is actually consistent with measurements of MMA solubility in water, which suggested a slightly negative effect of CD. However it is hard to explain such a phenomenon. Further, under other conditions it was found that CD either had no effect on chemically-initiated rate or could even increase it slightly. The only safe conclusion at this stage is that CD has no major effect on MMA kinetics, which arguably is consistent with MMA being relatively water soluble: intuitively one would expect that CD is most useful (‘catalytic’) for the EP of monomers of low solubility

A New Solar Technology Technique for Wastewater and Seawater Treatment

With the increasing water shortage in different parts of South-East Asia, like Singapore, and some parts of Indonesia and recently in Selangor, the need arises for more advanced technologies to treat wastewater to a level of purity where is can be used as potable. In this paper some improvements to an already available technique (the solar still) are introduced, in order to increase its productivity and make it more suitable to be used industrially, for large scale wastewater treatment projects. Problems facing the solar still are mainly related to the very low evaporation rate which is caused by the low effect of solar evaporation. Here we see a new idea to solve this problem, and introduce a low-cost application to treat wastewater, by trying to redesign the whole process under different parameters. Improvements introduced in this paper can also be used for seawater desalination

Solubility of Carbamazepine-Succinic Co-Crystal in Ethanolic Solvent System

Solubility of carbamazepine co-crystal produced from cooling co-crystallization process with succinic acid as a co-crystal former is investigated in this study. Two techniques are used to determine the solubility of the co-crystal which is gravimetric and HPLC.The solubility experiment in ethanol solvent system were conducted at 6 different temperatures (25, 30, 35, 40, 45 and 50°c) while for succinic acid solution system were conducted at 5 different concentration ratio. Both of the system are equilibrated for 72 hours. Result from the experiment has shown that the solubility of co-crystal is depending on temperature. As the temperature increase, the solubility of co-crystal also increased, this situation meets the Second Law of Thermodynamic which heat facilitates the dissolution process by providing more energy to the system

Solar Still: Water for the Future

Being an abundant natural resource that covers three quarters of the earth’s surface, water still a major issue, as less than 1% of fresh water is actually within human reach. Solar energy, most recommended renewable energy source is widely used in desalination fields. Solar distillation, particularly solar still is expected to solve this fresh water production problem without causing any fossil energy depletion, hydrocarbon ollution and environmental degradation. However, the efficiency of the solar still is debatable. As the main reason of low productivity in a solar still is the low heat transfer inside the unit itself therefore, a thoroughly modification on solar still design is presented based on the scope of increasing the heat transfer process inside the unit. Significantly, ntroducing optical controlling techniques together with focused sunlight receiver and having the process to operate under low pressure have speed up the rate of production within 10 hours of day light. However, the presence of focused sunlight receiver is not seem to improve the production of the solar still yet an increase value is recorded

Solar Still; Unrevealed Facts And Reasons Causing Its Low Productivity

As the current techniques for water desalination are very costly because of the high demand of electrical power or fossil fue, desalination of seawater using solar energy is one of the ways to meet the growing water demand at low cost. With the technologies currently available, solar still fresh water production rate is very low, compared to other techniques. The low production rate has been the main reason behind the lack of industrial usage of solar stills. As the maximum temperature which can be reached within the solar still is not very high, the evaporation rate inside the solar still remains low. This low temperature is the main reason for such a massive disadvantage, resulting in reduced heat transfer rate and slow vaporization process. This research aims at analyzing the reason for solar still low productivity, and suggesting some design modifications to solve such a crucial problem. This is done by dividing the solar still evaporation into four processes, then every process is thoroughly analyzed to solve the main problem, and to provide the maximum temperature and heat transfer rate inside the solar still. With this problem solved, use of solar still in industry can become a possibility

Densities and Kinematic Viscosities of a Quinary Regular Liquid System and Its Five Quaternary Subsystems at 293.15 K and 298.15 K

Densities and kinematic viscosities of a quinary regular liquid system and its five quaternary subsystems were measured at two different temperatures. Pure component properties of the quinary system octane (1) + heptane (2) + ethylbenzene (3) + cyclohexane (4) + toluene (5) have shown excellent agreement with previously reported data.Kinematic viscosity data obtained for different mixtures of this quinary system and its quaternary subsystems were used to test the predictive capability of selected viscosity models available from the literature