BIOFILM PRODUCTION BY FOOD-TRANSMITTED BACTERIA AND THEIR CONTROL BY SELECTED NANOPARTICLES

Biofilm is a population of bacteria attached to any types of surfaces and impeded in a self-produced matrix of extracellular polymeric substances. Biofilm exhibit up to 1000 fold antibiotic increased resistance to a broad range of antimicrobial agents. Several food-transmitted microorganisms are capable of forming biofilms and considered as a major source of contamination, transmission and infection. In the last few decades, nanoparticles has gained a great attention for their potential applications as antimicrobial agents. The aim of this work was to assess the biofilm formation capacity of food-transmitted bacteria under various environmental conditions and to investigate the efficacy of different nanoparticles (i.e. Ag-Cu-B, Ag-Na-B, and Ag-Mg-B) to kill microbial pathogens in biofilms. Nanoparticles were synthesized by using co-precipitation and microwave techniques and characterized for their physiochemical properties by transmission electron microscopy and light dynamic scattering. The antibiofilm and antimicrobial properties of the synthesized nanoparticles were investigated using S. aureus (10 strains), P. aeruginosa and E. coli (3strains). The findings revealed that all NPs significantly inhibited planktonic cells and biomass of the grown biofilms. Moreover, the sanitization efficacy of nanoparticles were assessed on stainless steel surface that commonly come into contact with food. The surfaces were inoculated with strains of S. aureus and Salmonella and cleaned with NPs saturated sanitary wipes. A significant reduction was observed in viability of the cells on the stainless steel surfaces. The results demonstrated that the use of NPs incorporated into sanitary wipes is useful method to eliminate bacteria on food contact surfaces

Biology and assessment of the painted sweetlips (Diagramma pictum (Thunberg, 1792)) and the spangled emperor (Lethrinus nebulosus (Forsskål, 1775)) in the southern Arabian Gulf

The population biology and status of the painted sweeplips (Diagramma pictum) and spangled emperor (Lethrinus nebulosus) in the southern Arabian Gulf were established by using a combination of size-frequency, biological, and size-at-age data. Transverse sections of sagittal otoliths were characterized by alternating translucent and opaque bands that were validated as annuli. Comparisons of growth characteristics showed that there were no significant differences (P>0.05) between sexes. There were well defined peaks in the reproductive cycle, spawning occurred from April to May for both species, and the mean size at which females attained sexual maturity was 31.8 cm fork length (LF) for D. pictum and 27.6 cm (LF) for L. nebulosus. The mean sizes at first capture (21.1 cm LF for D. pictum and 26.4 cm LF for L. nebulosus) were smaller than the sizes for both at first sexual maturity and those at which yield per recruit would be maximized. The range of fishing-induced mortality rates for D. pictum (0.37−0.62/yr) was substantially greater than the target (Fopt=0.07/yr) and limit (Flimit=0.09/ yr) estimates. The range of fishing-induced mortality rates for L. nebulosus (0.15/yr to 0.57/yr) was also in excess of biological reference points (Fopt=0.10/yr and Flimit=0.13/yr). In addition to growth overfishing, the stocks were considered to be recruitment overfished because the biomass per recruit was less than 20% of the unexploited levels for both species. The results of the study are important to fisheries management authorities in the region because they indicate that both a reduction in fishing effort and mesh-size regulations are required for the demersal trap fishery

On Systems of Systems Engineering: Online Distance Education Systems Key Challenges

Technology development have affected educational delivery around the world. The utilization and implementation of online learning is rising at a staggering manner. Online Distance learning has become an urgent need recently. The use of distance learning has appeared in the past ten years, the learning has been extended by the technology from classrooms in the schools into online learning. Online Learning adopted in various universities, educational institutions and schools worldwide. Recently, with the emergency situations due to the epidemic of COVID -19, and according to the recommendations by World Health Organization for social distance, most of the educational institutions worldwide tend to utilize the online learning instead of traditional learning. Although the online learning has been implemented years ago, still it faces challenges. The author of this research paper aim to explore the key challenges that reported while implementing Online Distance Education System as Systems of Systems. The author then outlines research agenda that identifies 11 research themes that can be considered as a solution for the current Online Distance Education System implementations challenges

Polymeric Nanofibrous Media for Enhanced Ground Water Filtration

Water is one of the bulk transportation media for transmission of particulate contaminants. These contaminants are complex mixtures of particles; most of them are usually smaller than 1000 µm in diameter. Chemical and biological aerosols (particulates) are frequently in the range of 1- 10 µm. The particulate matters may carry some adsorbed gaseous contaminants. The removal of particulate and biological contaminants is thus an important step in water purification process. Particulate contaminants if not removed tend to foul reverse osmosis membranes and severely reduce the throughput of the final purification step. The filtration industry is looking for more efficient high performance filters for filtration of particles smaller than 0.3 µm and adsorbed toxic gases. Nanofibrous media have low basis weight, high permeability and small pore size that make the appropriate for a wide range of filtration applications. In addition, nanofiber membrane offers unique properties such as high surface area (ranging from 1- 35 m2/g depending on the diameter of fibers), good interconnectivity of pores and potential to incorporate active chemistry or functionality on nanoscale. The current study investigated the formation of nanofibrous membranes, from a cellulose precursor; cellulose acetate, for water filtration. Membranes were prepared by an electrospinning technique that was based on the use of a high voltage power supply to force polymeric droplets to be sprayed in the form of fibers with different aspect ratios, depending on the process parameters. Different parameters affecting the structure, morphology and physical properties of the membranes were studied in details in order to optimize them. Characterization of the membranes was carried out at every stage of the electro spinning process by infrared spectroscopy (IR) and scanning electron microscopy (SEM). Physical properties of the membranes such as density, porosity, BET surface area, pore size distribution, viscosity and surface tension were determined. Thermal treatment effects on the structure and morphology of the membranes were studied. Regeneration of cellulose was attempted by treatment of the membranes in alkaline media. Optimization of the alkali treatment process was also reached. Preliminary evaluation of the nanofibrous membranes for removing solid particulates from simulated solutions was also carried out. Filtration efficiency results were compared to those obtained with two commercially available membranes. Results showed the possibility of obtaining nanofibrous membranes from solutions containing different concentrations of cellulose acetate, and showed a wide range of fiber and pore size distribution. Optimization of the electro spinning parameters led to the formation of highly porous membranes (with porosity approaching 94%) together with homogeneous fiber and pore size distributions. Structure instability was observed with the thermal treatment of these membranes and was found to be dependent on the membrane thickness. Treatment of the CA membranes in 0.5M NaOH solutions yielded a fully regenerated cellulose after 10 hours, without affecting the morphology of the nanofibers nor the pore size and its distribution. Efficiency of the nanofibrous membranes prepared in the current study showed superiority over the commercially available membranes

THE ROLE OF SCHOOL PRINCIPALS IN FOSTERING THE TEAMWORK SUCCESS IN AL AIN SCHOOLS FROM TEACHERS’ PERCPECTIVE

The aim of the present study is to investigate the role of principals in fostering teamwork success. This study explained the leadership practices in fostering teamwork as perceived by teachers. Notably, the teamwork and its importance are neglected most of the time. Additionally, very little work was found in context of UAE. A sample of 334 public school teachers from Al Ain completed the online survey about their satisfaction about teamwork rates, their views regarding principals fostering teamwork, as well as recommendations and suggestions that could promote teamwork among school teachers. Descriptive statistics is adopted to analyze the quantitative items of the study. The teachers\u27 responses to the items are analyzed on a five-point Likert-scale. This study is guided by three questions. The first examines the perspectives of Al Ain school teachers about challenges and obstacles that may hinder teamwork success within the school. The second question is about how school teachers in Al Ain understand successful teamwork practices of principals, while the third question looks into the teachers’ views for teamwork success regarding the role of the principals. The findings indicate that there is a strong relation between the leadership structure and performance evaluation of the teachers. Findings reveals that principals usually foster teamwork but there is still a need to take initiatives like increasing the teachers’ involvement in decision-making process, providing administrative support, and collaborating with the teachers. The study enlists the working environment, lack of teachers\u27 involvement in decision-making process as the major hindrances to teamwork. The present study derives its weight from focusing mainly Al Ain schools in the UAE since the work in this area is very scares and, consequently, it can provide some practical insights to apply by schools. The study recommends to reinforce the role of Ministry of Education to provide workshops about making-decision and the importance of teamwork between principals and teachers

GROUND STATES AND GIBBS MEASURES OF λ-MODEL ON CAYLEY TREE OF ORDER TWO

Abstract Statistical mechanics deals with the average properties of a mechanical system. Some examples are; the water in a kettle, the atmosphere inside a room and the number of atoms in a magnet bar. These kinds of systems are made up of a large number of components, usually molecules. The observer has restricted power to consider all the components. All that can be done is to specify a few average quantities of the system such as its density, pressure or temperature. The main objective of statistical mechanics is to predict the relationship between the observable macroscopic properties of the system, given only a knowledge of the microscopic interactions between the components. The present thesis is devoted to a model whose interacting molecules are located on nearest neighbor vertices of a Cayley tree. In this thesis, ground states and Gibbs measures of λ-model on a Cayley tree of order two are investigated. This investigation is closely related to the phase transitions phenomenon for lattice models on trees, by considering the model where spin has only three values. This kind of model aims to describe all its ground states and study phase transition phenomena by using Gibbs measures

Biological efficiency of recycling organic waste with edible fungi

Mushrooms has been known as important cultivars for their nutritional and medicinal values, the species Pleurotus sajor caju and Calocybe indica were selected in this investigation for being used in previous studies to be grown on different lignocellulosic materials. Cultivating mushrooms on plant wastes is value-added way to produce a source of human food and is an efficient way to recycle those residues. Date palm leaf waste, date palm bunch waste and mowed turf grass waste were used as mushroom growing substrates. Date palm is the most important plant grown in the UAE and it produce tons of wastes every year similarly with the turf grass. This study aims to use sustainable and novel technology for recycling organic waste for value addition with reference to UAE. The objectives focuses on assessing the bio efficiency of two different mushroom species in degrading the organic waste materials, the quality of spent waste to utilize it as organic matter for enriching the soil, the quality of spent waste in terms of using as ruminant feed and the comparable quality of mushrooms. Parameters that were tested are: growing period, fresh and dry weight of the yield, biological efficiency, macro-nutrients and trace minerals, proline, crude fiber and protein. It was concluded that concluded that the Pleurotus sajor has a higher nutritional value than Calocybe indica and date palm bunch waste has the higher values between three used substrates to be used in animal feed and soil enrichmen

NATURAL RADIOACTIVITY IN GROUNDWATER, ROCKS AND SEDIMENTS FROM SOME AREAS IN THE UAE: DISTRIBUTION, SOURCES AND ENVIRONMENTAL IMPACT

Groundwater contains a certain amount of natural radioactivity that generally results from the decay of uranium, thorium and 40K isotopes. Knowledge of concentration levels, spatial distribution and sources of these isotopes in groundwater is crucial for environmentally safe and sustainable groundwater resources in the United Arab Emirates (UAE). This dissertation focuses on investigating the distribution, environmental impact and sources of 235U, 238U, 232Th, as well as the activity of gross β and α in groundwater in some locations in the UAE. Additionally, groundwater samples from Oman and selected aquifer rocks and sediments from the UAE were analyzed for comparison. A variety of techniques including liquid scintillation counter, ICP-MS, ICP-OES and ICP-SFMS, were used for the analyses. The results reveal considerable differences in radioactivity in terms of spatial and local variability and show relatively high concentrations of 238U in some locations. Most of the 238U concentrations in the groundwater are below the World Health Organization permissible limit for drinking water. The relatively high uranium concentrations in some aquifers suggest a long period of geochemical interactions between rocks, sediments and water as well as possible contribution from fertilizers. In coastal aquifers, however, seawater intrusion is expected to be an additional source of uranium. The 232Th concentrations were generally comparable and relatively low in all groundwater samples due to the low solubility of thorium in water. Results of the uranium distribution in the rocks and sediments indicate higher concentration in the sediments and further support the possible effect of fertilizers as an additional source of uranium. The activity of gross β and gross α were found to exceed the WHO permissible limits for drinking water in 77% and 13% of the groundwater samples, respectively. The most likely reason for this phenomenon is occurrence of 40K, 228Ra and 226Ra in the aquifer body. The results of groundwater samples from Oman indicate low levels of 235U, 238U and 232Th, and the activity of 222Rn and 226 Ra were lower than the WHO permissible limits for drinking water. Dilution of groundwater by relatively high rainfall can be a possible cause of the relatively low activity of the radionuclides in Oman and other regions in the world