366 research outputs found
Faculty Members Perspectives on the Impact of Educational Technology on the Teaching and Learning Process at the University of Sharjah
Educational technology is increasingly being employed in universities to boost students learning and performance. It became a key component of communication, information storage and transmission, audio-visual media usage and creation, and knowledge sharing. The purpose of the study is to determine the impact of modern educational technologies on education quality and development at the College of Arts and Humanities at Sharjah University from the perspective of faculty members by developing a questionnaire with (20) items and distributing it to a random sample of (91) faculty members. According to the studys findings, the usage of educational technology has a significant impact on education, not just in terms of boosting instructors communication skills, instructional techniques, and advising students on how to utilize this technology. We actively support the employment of as much information technology as possible in the classroom in order to increase instructors abilities and students knowledge
CLIMATE RISK AND FOOD SECURITY IN MALI
We combine socioeconomic data from a largeâscale household survey with historical climate data to map the climate sensitivity of availability and access dimensions of food security in Mali, and infer the ways in which atârisk communities may have been impacted by persistent climatic shift. Thirty years after 1982â1984, the period of most intense drought during the protracted late 20th century drying of the Sahel, the impact of drought on livelihoods and food security is still recognizable in the Sahelian center of Mali. This impact is expressed in the larger fraction of households in this Sahelian center of the countryâthe agroâecological transition between pastoralism in the north, and sedentary agriculture in the southâwho practice agriculture but not livestock raising, despite environmental conditions that are suitable to their combination. These households have lower food security and rely more frequently on detrimental nutritionâbased coping strategies, such as reducing the quantity or quality of meals. In contrast, the more food secure households show a clear tendency toward livelihood diversification away from subsistence agriculture. These households produce less of what they consume, yet spend less on food in proportion. The analysis points to the value of interdisciplinary researchâin this case bridging climate science and vulnerability analysisâto gain a dynamical understanding of complex systems, understanding which may be exploited to address realâworld challenges, offering lessons about food security and local adaptation strategies in places among the most vulnerable to climate
Molybdenum isotopes in plume-influenced MORBs reveal recycling of ancient anoxic sediments
Under modern oxidising Earth surface conditions, dehydrated subducted slabs show Mo isotope compositions as low as ÎŽ98/95Moâ=ââ1.5 â°, compared to the depleted mantle ÎŽ98/95Moâ=ââ0.2 â°. Such light Mo isotope compositions reflect the redox-dependent aqueous mobility of isotopically heavy Mo associated with slab dehydration. Here we analysed basaltic glasses from the South-Mid Atlantic Ridge, whose parental melts are influenced by the enriched Discovery and Shona mantle plumes. We report increasingly higher ÎŽ98/95Mo of up to â0.1 â° from the most depleted samples towards those tapping more enriched mantle sources. ÎŽ98/95Mo values correlate with radiogenic Sr and Nd isotopes, which indicates the recycling of Proterozoic sediments with a Mo isotopic composition that was not affected by subduction-related, oxic dehydration. We propose that the Mo isotope signatures were retained during subduction and reflect anoxic conditions during deep sea sedimentation in the mid-Proterozoic. Finally, Mo isotope fractionation between different terrestrial reservoirs likely depends on the slab redox budget, and therefore on the timing of subduction with regard to Earthâs surface oxygenation
Primordial metallic melt in the deep mantle
Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3â3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis
Lignin-Based Polyols with Controlled Microstructure by Cationic Ring Opening Polymerization
Lignin-based polyols (LBPs) with controlled microstructure were obtained by cationic ring opening polymerization (CROP) of oxiranes in an organosolv lignin (OL) tetrahydrofuran (THF) solution. The control on the microstructure and consequently on the properties of the LBPs such as hydroxyl number, average molecular weight, melting, crystallization and decomposition temperatures, are crucial to determine the performance and application of the derived-products. The influence of key parameters, for example, molar ratio between the oxirane and the hydroxyl groups content in OLO, initial OL concentration in THF, temperature, specific flow rate and oxirane nature has been investigated. LBPs with hydroxyl numbers from 35 to 217 mg KOH/g, apparent average Mw between 5517 and 52,900 g/mol and melting temperatures from â8.4 to 18.4 °C were obtained. The CROP procedure allows obtaining of tailor-made LBPs for specific applications in a very simple way, opening the way to introduce LBPs as a solid alternative to substitute currently used fossil-based polyols.Basque Government (grant KK-2019/00097
Near-equilibrium isotope fractionation during planetesimal evaporation
Silicon and Mg in differentiated rocky bodies exhibit heavy isotope
enrichments that have been attributed to evaporation of partially or entirely
molten planetesimals. We evaluate the mechanisms of planetesimal evaporation in
the early solar system and the conditions that controlled attendant isotope
fractionations. Energy balance at the surface of a body accreted within ~1 Myr
of CAI formation and heated from within by 26Al decay results in internal
temperatures exceeding the silicate solidus, producing a transient magma ocean
with a thin surface boundary layer of order < 1 meter that would be subject to
foundering. Bodies that are massive enough to form magma oceans by radioisotope
decay (ge 0.1%) can retain hot rock vapor even in the absence of ambient
nebular gas. We find that a steady-state rock vapor forms within minutes to
hours and results from a balance between rates of magma evaporation and
atmospheric escape. Vapor pressure buildup adjacent to the surfaces of the
evaporating magmas would have inevitably led to an approach to equilibrium
isotope partitioning between the vapor phase and the silicate melt. Numerical
simulations of this near-equilibrium evaporation process for a body with a
radius of ~ 700 km yield a steady-state far-field vapor pressure corresponding
to 95% saturation. Approaches to equilibrium isotope fractionation between
vapor and melt should have been the norm during planet formation due to the
formation of steady-state rock vapor atmospheres and/or the presence of
protostellar gas. We model the Si and Mg isotopic composition of bulk Earth and
show that the best fit is for a carbonaceous chondrite-like source material
with about 12% loss of Mg and 15% loss of Si resulting from near-equilibrium
evaporation into the solar protostellar disk of hydrogen gas on timescales of
10,000 to 100,000 years.Comment: 35 pages, 15 figure
Influence of chitin nanocrystals on the dielectric behaviour and conductivity of chitosan-based bionanocomposites
A series of bionanocomposite films based on chitosan, reinforced with chitin nanocrystals, were developed, and assessed in terms of dielectric behaviour and conductivity by using an experimental methodology that allows avoiding the conductivity contribution and the exclusion of contact and interfacial polarization effects. The dielectric relaxations at low and high frequency and temperatures were modeled by Havriliak-Negami functions. Below the glass transition temperature (Tg), the Îł and ÎČ relaxations were observed, which were related to intramolecular and non-cooperative segmental movements. At higher temperatures, an intermolecular and cooperative macromolecular movement, related to the glass transition, gave rise to α-relaxation. In addition, two over-Tg ÏI and ÏII relaxations were found, which were related to the displacement of dipoles in the disordered structure of bionanocomposites. The addition of chitin nanocrystals did not affect the apparent activation energy Ea of the Îł-relaxation. However, it decreased the Ea of the ÎČ-relaxation and increased the free volume at temperatures in the vicinities of the α-relaxation. Finally, the electric conductivity of the bionanocomposites was lower than that of neat chitosan and chitin due to the interaction between the OH and NH2 groups that reduced the ionic mobility, along with the increase of free volume, with the subsequent separation of phases
Study on Sorption Characteristics of Critic Acid Modified Rape-seed Pellet Considering the Chemical Pre-treatment Processes
The ground rape-seed pellet was pre-treated then reacted with citric acid which resulted in a rape-seed citrate having ion
exchange capacity. The effects of pre-treatment steps (including extraction of fatty substances by organic solvent, moreover
acidic and alkali treatment of the rape-seed pellet) on the ion binding capacity of the materials were investigated. The
capacity was determined for three cations (copper, zinc and nickel) separately, from aqueous solutions in batch mode of
operation.
Based on the experimental results it was found that the highest ion exchange capacity for all the cations was obtained
by the process involved the pre-treatment combining of extraction and alkali treatment followed by the reaction with the
citric acid
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