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Adsorption desalination: Advances in porous adsorbents
No full textWith the continuous growth of the world population, the demand for fresh water is ever increasing. Water desalination is a means of producing fresh water from saline water, and one of the proposed solutions in the scientific community for solving the current global freshwater shortage. Adsorption is foreseen as a promising technology for desalination due to its relatively low energy requirements, low environmental impact, low cost and high salt removal efficiency. More importantly, chemicals are not required in adsorption processes. Active carbons, zeolites, carbon nanostructures, graphene and coordination framework materials are amongst the most investigated adsorbents for adsorption desalination, which show different performances regarding adsorption rate, adsorption capacity, stability and recyclability. In this review, the latest adsorbent materials with their features are assessed (using metrics) and commented critically, and the current trend for their development is discussed. The adsorption mode is also reviewed, which can provide guidance for the design of adsorbents from the engineering application point of view
A methodology to evaluate solvent extraction-based processes considering techno-economic and environmental sustainability criteria for biorefinery applications
No full textExtraction processes are widely used in biorefinery applications to recover target products from biomass, and their comprehensive evaluation is key to improving their economic and environmental sustainability. This paper applies a systematic methodology that combines a rigorous process design, techno-economic analysis, and life cycle assessment to evaluate the sustainability performance of solvent extraction-based processes, with a focus on downstream activities. The methodology, which consists of seven iterative steps that combine process simulation, economic and environmental sustainability assessment tools, is demonstrated using a biodiesel production process from algae biomass, with hexane as the lipid extraction solvent. The minimum biodiesel selling price is estimated at $8.95 per US gal, using the discounted cash flow rate of return. This is 3.5 times the average price of fossil diesel, mostly due to the cost of algae biomass and lipid recovery capacity of the solvent. Eighteen environmental impact categories are estimated from cradle to grave using the ReCiPe V1.1 method. For example, the climate change and primary energy demand are calculated at 95 g CO2 eq./MJ and 1.52 MJ/MJ biodiesel, which are 5% and 24% higher compared to fossil diesel, respectively. Lipid extraction is identified as the hotspot of the downstream processing stages for all impact categories (52% - 97%), and an opportunity for improving the overall sustainability performance of algae biodiesel, e.g. solvent selection. These findings provide a benchmark for future improvements to biodiesel production from algae biomass, with focus on the interactions between biomass and the solvent, e.g. phase equilibrium thermodynamics
Genetics of Childhood Hearing Loss
No full textCompelling evidence indicates that some newborns harboring genetic variants associated with deafness/hard-of-hearing (DHH) may not be identified by current physiologic NBHS rendering current NBHS suboptimal. Incorporating GS into NBHS would improve clinical diagnosis and decrease time to early intervention efforts
Privacy-Enhancing Settlements Protocol in Peer-to-Peer Energy Trading Markets
No full textThis paper proposes a privacy-friendly billing and settlements system for use in peer-to-peer energy trading markets. More specifically, it proposes a privacy-enhancing settlements protocol (PESP) which makes use of a partial homomorphic encryption scheme to facilitate private processing and computation of smart grid users’ monthly energy bill by a semitrusted third party. In addition, it allows for minor financial penalties to users who participate in peer-to-peer trading but do not accurately predict their energy usage for each period and, as such, import or export varying amounts compared to the amount they have agreed to trade for initially. This encourages predictions to be accurate to help keep the trading fair and aiding suppliers tomake accurate predictions about the amount of electricity needed for each trading period. Our security analysis and performance evaluation demonstrate that PESP protects users’ privacy and isefficient in terms of computation and communication cost.Index Terms—Privacy, Peer-to-Peer, Energy Trading, Billing and Settlemen
Organometallic Lanthanide Bismuth Cluster Single-Molecule Magnets
No full textSingle-molecule magnets (SMMs) are molecules that can retain magnetic polarization in the absence of an external magnetic field and embody the ultimate size limit for spin-based information storage and processing. Multimetallic lanthanide complexes lacking magnetic exchange coupling enable fast relaxation pathways that attenuate the full potential of these species. Employment of diamagnetic heavy main group elements with diffuse orbitals may lead to unprecedented strong coupling. Herein, two bismuth cluster bridged lanthanide complexes, [K(THF)4]2[Cp*2Ln2Bi6] (Cp* = pentamethylcyclopentadienyl; 1-Ln, Ln = Tb, Dy), were synthesized via a solution organometallic approach. The neutral [Ln2Bi6] heterometallocubane core features lanthanide centers that are bridged by a rare Bi66- Zintl ion which supports strong ferromagnetic interactions between lanthanides. This affords the rare observation of magnetic blocking and open hysteresis loops for superexchange-coupled SMMs comprising solely lanthanide ions. Both compounds constitute the first SMMs containing bismuth donors paving the way for promising synthetic targets for quantum computation
CORE COMPONENTS: SEL THEORY PRACTICE RESEARCH
No full textAlthough Social and Emotional Learning (SEL) is seen to benefit children and youth, evidence is largely built on summative trials of programmes, with little comparative insight into the specific approaches that underpin SEL. The current study sought to highlight a hitherto underutilised approach in identifying common SEL practices through the identification of ‘core components’. Both instructional (‘how’ SEL is taught) and practice-based (‘what’ SEL is taught) elements were examined across 13 elementary level evidence-based programmes through a method of distillation of skills and practices. Findings showed a discrepancy between theorised SEL and identified components, consistent with emergent literature. Further, the study is the first to cross-examine practice and instruction elements, linking prevalent pedagogical approaches to specific SEL skills. The implications for core components as an approach are discussed in respect to a refinement of theory, considerations for teaching practices, and recommendations for the design of future research in SEL evaluation. Keywords: social and emotional learning; SEL; core components; universal intervention<br/
Biogeochemical Cycling of 99Tc in Alkaline Sediments
No full text99Tc will be present in significant quantities in radioactive wastes including intermediate level wastes (ILW). The internationally favoured concept for disposing of ILW is via deep geological disposal in an underground engineered facility located approximately 200 – 1000 m deep. Typically, in the deep geological disposal environment the subsurface will be saturated, cement will be used extensively as an engineering material, and iron will be ubiquitous. This means that understanding Tc biogeochemistry in high pH, cementitious environments is important to underpin safety case development. Here, alkaline sediment microcosms (pH 10) were incubated under anoxic conditions under no added Fe(III) and with added Fe(III) conditions (added as ferrihydrite) at three Tc concentrations (10-11, 10-6, and 10-4 mol L-1). In the 10-6 mol L-1 Tc experiments with ‘no added Fe(III)’, approximately 35% Tc(VII) removal occurred during bioreduction. Solvent extraction of the residual solution phase indicated that approximately 75% of Tc was present as Tc(IV), potentially as colloids. In both biologically active and sterile control experiments ‘with added Fe(III)’, Fe(II) formed during bioreduction and greater than 90% Tc was removed from the solution, most likely due to abiotic reduction mediated by Fe(II). X-ray absorption spectroscopy (XAS) showed that in bioreduced sediments, Tc was present as hydrous TcO2-like phases, with some evidence for an Fe association. When reduced sediments with added Fe(III) were air oxidised, there was a significant loss of Fe(II) over 1 month (approximately 50%), yet this was coupled to only modest Tc remobilisation (approximately 25%). Here, XAS analysis suggested with air oxidation, partial incorporation of Tc(IV) into newly forming Fe oxyhydr(oxide) minerals may be occurring. These data suggest that in Fe-rich, alkaline environments, biologically mediated processes may limit Tc mobility
Stability and Optimization of Speculative Queueing Networks
No full textWe provide a queueing-theoretic framework for job replication schemes based on the principle “replicate a job as soon as the system detects it as a straggler”. This is called job speculation. Recent works have analyzed replication on arrival, which we refer to as replication. Replication is motivated by its implementation in Google’s BigTable. However, systems such as Apache Spark and Hadoop MapReduce implement speculative job execution. The performance and optimization of speculative job execution is not well understood. To this end, we propose a queueing network model for load balancing where each server can speculate on the execution time of a job. Specifically, each job is initially assigned to a single server by a frontend dispatcher. Then, when its execution begins, the server sets a timeout. If the job completes before the timeout, it leaves the network, otherwise the job is terminated and relaunched or resumed at another server where it will complete. We provide a necessary and sufficient condition for the stability of speculative queueing networks with heterogeneous servers, general job sizes and scheduling disciplines. We find that speculation can increase the stability region of the network when compared with standard load balancing models and replication schemes. We provide general conditions under which timeouts increase the size of the stability region and derive a formula for the optimal speculation time, i.e., the timeout that minimizes the load induced through speculation. We compare speculation with redundant-d and redundant-to-idle-queue-d rules under an S&X model. For light loaded systems, redundancy schemes provide better response times. However, for moderate to heavy loadings, redundancy schemes can lose capacity and have markedly worse response times when compared with the proposed speculative scheme.Index Terms—speculation, replication, parallel servers, load balancing, stabilit
Generative Adversarial Networks for Synthetic Data Generation: A Comparative Study
No full textGenerative Adversarial Networks (GANs) are gaining increasing attention as a means for synthesising data. So far much of this work has been applied to use cases outside of the data confidentiality domain with a common application being the production of artificial images. Here we consider the potential application of GANs for the purpose of generating synthetic census microdata. We employ a battery of utility metrics and a disclosure risk metric (the Targeted Correct Attribution Probability) to compare the data produced by tabular GANs with those produced using orthodox data synthesis methods
