The Stability of Ferrate(VI) in Water and Its Impacts on Disinfection Byproduct Precursors

Ferrate has been proposed as an alternative pre-oxidant in drinking water treatment for many years. Despite extensive studies that examined ferrate oxidation of specific contaminants, little research has been done on the impacts of ferrate in raw waters that include natural organic matter (NOM) and bromide, and that are also treated with coagulants and chlorine. The future of ferrate as a potable water treatment chemical depends on its ability to achieve adequate disinfection while minimizing the formation of disinfection byproducts (DBPs) under these realistic scenarios. In this work, laboratory-scale treatment studies were conducted to (1) clarify the stability of ferrate in natural waters under various conditions, (2) re-examine the ability of ferrate to oxidize bromine species, (3) explore the interactions of ferrate and coagulants in controlling DBP precursors, and (4) compare ferrate with ozone as alternative pre-oxidants. Results showed that ferrate decay was catalyzed by ferrate decomposition products. Solutes capable of forming complexes with iron hydroxides retarded ferrate decay. In natural waters, NOM and bicarbonate inhibited the catalytic effects of ferrate decomposition products and stabilized ferrate. Ferrate can oxidize bromide forming bromine and bromate, and in natural waters total organic bromine (TOBr) was also detected. The highest levels of bromine and bromate were formed at lower pH and in the absence of phosphate. Nevertheless, under environmentally relevant conditions, the formation of bromate and TOBr would not be a problem for ferrate application as their concentration levels are quite low. The effectiveness of ferrate oxidation in combination with conventional treatment on DBP precursor removal was investigated. Results showed that intermediate-ferrate treatment (i.e., conventional treatment followed by ferrate oxidation) was most effective followed by pre-ferrate treatment (i.e., ferrate oxidation followed by conventional treatment) or conventional treatment alone, and the least effective was ferrate oxidation alone. The effects of ferrate and ozone pre-oxidation on DBP formation from subsequent chlorination or chloramination were comparable at equivalent doses for most DBP species. Ozone led to higher haloketone and chloropicrin formation potentials than ferrate. The relative performance of ferrate versus ozone for DBP precursor removal was affected by water quality, DBP species, and oxidant dose

Energy-efficient Compressive Data Gathering Utilizing Virtual Multi-input Multi-output

Data gathering is an attractive operation for obtaining information in wireless sensor networks (WSNs). But one of important challenges is to minimize energy consumption of networks. In this paper, an integration of distributed compressive sensing (CS) and virtual multi-input multi-output (vMIMO) in WSNs is proposed to significantly decrease the data gathering cost. The scheme first constructs a distributed data compression model based on low density parity check-like (LDPC-like) codes. Then a cluster-based dynamic virtual MIMO transmission protocol is proposed. The number of clusters, number of cooperative nodes and the constellation size are determined by a new established optimization model under the restrictions of compression model. Finally, simulation results show that the scheme can reduce the data gathering cost and prolong the sensor network’s lifetime in a reliable guarantee of sensory data recovery quality

Contagion processes on the static and activity driven coupling networks

The evolution of network structure and the spreading of epidemic are common coexistent dynamical processes. In most cases, network structure is treated either static or time-varying, supposing the whole network is observed in a same time window. In this paper, we consider the epidemic spreading on a network consisting of both static and time-varying structures. At meanwhile, the time-varying part and the epidemic spreading are supposed to be of the same time scale. We introduce a static and activity driven coupling (SADC) network model to characterize the coupling between static (strong) structure and dynamic (weak) structure. Epidemic thresholds of SIS and SIR model are studied on SADC both analytically and numerically with various coupling strategies, where the strong structure is of homogeneous or heterogeneous degree distribution. Theoretical thresholds obtained from SADC model can both recover and generalize the classical results in static and time-varying networks. It is demonstrated that weak structures can make the epidemics break out much more easily in homogeneous coupling but harder in heterogeneous coupling when keeping same average degree in SADC networks. Furthermore, we show there exists a threshold ratio of the weak structure to have substantive effects on the breakout of the epidemics. This promotes our understanding of why epidemics can still break out in some social networks even we restrict the flow of the population

Dual Functions of Interferon Regulatory Factors 7C in Epstein-Barr Virus–Mediated Transformation of Human B Lymphocytes

Epstein-Barr virus (EBV) infection is associated with several human malignancies. Interferon (IFN) regulatory factor 7 (IRF-7) has several splicing variants, and at least the major splicing variant (IRF-7A) has oncogenic potential and is associated with EBV transformation processes. IRF-7C is an alternative splicing variant with only the DNA-binding domain of IRF-7. Whether IRF-7C is present under physiological conditions and its functions in viral transformation are unknown. In this report, we prove the existence of IRF-7C protein and RNA in certain cells under physiological conditions, and find that high levels of IRF-7C are associated with EBV transformation of human primary B cells in vitro as well as EBV type III latency. EBV latent membrane protein 1 (LMP-1) stimulates IRF-7C expression in B lymphocytes. IRF-7C has oncogenic potential in rodent cells and partially restores the growth properties of EBV-transformed cells under a growth-inhibition condition. A tumor array experiment has identified six primary tumor specimens with high levels of IRF-7C protein—all of them are lymphomas. Furthermore, we show that the expression of IRF-7C is apparently closely associated with other IRF-7 splicing variants. IRF- 7C inhibits the function of IRF-7 in transcriptional regulation of IFN genes. These data suggest that EBV may use splicing variants of IRF-7 for its transformation process in two strategies: to use oncogenic properties of various IRF-7 splicing variants, but use one of its splicing variants (IRF-7C) to block the IFN-induction function of IRF-7 that is detrimental for viral transformation. The work provides a novel relation of host/virus interactions, and has expanded our knowledge about IRFs in EBV transformation

A Genetic and Simulated Annealing Combined Algorithm for Optimization of Wideband Antenna Matching Networks

A genetic and simulated annealing combined algorithm is presented and applied to optimize broadband matching networks for antennas. As a result, advantages of both the genetic algorithm (GA) and simulated annealing (SA) are taken. Effectiveness and efficiency of the presented combined algorithm are demonstrated by optimization of a wideband matching network for a VHF/UHF discone-based antenna. The optimized parameters provide significant improvements of VSWR and transducer power gain for the antenna

Laboratory Assessment of Ferrate for Drinking Water Treatment

A laboratory assessment of ferrate (Fe(VI)) for drinking water treatment was conducted, including batch and continuous flow experiments on natural water samples. In batch experiments, ferrate preoxidation enhanced the removal of ultraviolet light-absorbing compounds (UV254; absorbance at 254 nm) by subsequent coagulation in some water samples, while some samples showed no improvement. Ferrate oxidation was not found to have negative impacts on subsequent coagulation. In continuous flow experiments, ferrate preoxidation improved finished water turbidity, UV254 absorbance, and disinfection by-product formation as compared with no preoxidation and to preoxidation with permanganate. However, improvements were similar in magnitude to those achieved by adding the same mass of ferric iron in place of ferrate prior to a formal coagulation step, in one water study. Particulate iron resulting from Fe(VI) reduction was effectively destabilized and removed via coagulation and filtration. Ferrate may be a viable technology for drinking water treatment depending on raw water quality and treatment goals

Leaders’ response to employee overqualification:An explanation of the curvilinear moderated relationship

This research aimed to advance overqualification literature by examining how leaders’ perceived employee overqualification (LPEO) influences their empowering behaviour and employee work behaviours. Drawing upon the individualized leadership theory, we proposed that LPEO has an inverted U-shape relationship with their empowering behaviour such that leaders are more motivated to empower employees from low to moderate levels of overqualification, but this tendency decreases after a certain inflection point. We also predicted that the inflection point occurs at a lower level of employee overqualification when leaders perceive higher (vs. lower) status threats. Leader empowering behaviour was hypothesized to positively predict employees’ voice and negatively predict their withdrawal behaviour. Two multi-source and time-lagged studies were conducted to examine this moderated mediation curvilinear model. In Study 1, survey data from 372 leader–employee dyads supported the inverted U-shape mediation model from leaders’ perceived overqualification to empowering behaviour, then to employee outcomes (i.e., voice and withdrawal behaviour). In Study 2, we collected data from a sample of 73 team leaders and 286 employees, and the results supported the full model. Taken together, these findings offer a perspective to enrich the understanding of employee overqualification and have important practical implications.Practitioner pointsWhen leaders regard employees as overqualified, they can assist them via the means of appropriate empowerment to best utilize their skills to benefit the company.Leader empowerment can inspire employees’ voice behaviour but reduce their withdrawal behaviours.To minimize potentially negative aspects from highly overqualified employees, organizations should reduce leaders’ concern about the status threat, and encourage leaders’ proactive responses to these employees so as to achieve positive returns from overqualified employees

Leaders’ response to employee overqualification:An explanation of the curvilinear moderated relationship

This research aimed to advance overqualification literature by examining how leaders’ perceived employee overqualification (LPEO) influences their empowering behaviour and employee work behaviours. Drawing upon the individualized leadership theory, we proposed that LPEO has an inverted U-shape relationship with their empowering behaviour such that leaders are more motivated to empower employees from low to moderate levels of overqualification, but this tendency decreases after a certain inflection point. We also predicted that the inflection point occurs at a lower level of employee overqualification when leaders perceive higher (vs. lower) status threats. Leader empowering behaviour was hypothesized to positively predict employees’ voice and negatively predict their withdrawal behaviour. Two multi-source and time-lagged studies were conducted to examine this moderated mediation curvilinear model. In Study 1, survey data from 372 leader–employee dyads supported the inverted U-shape mediation model from leaders’ perceived overqualification to empowering behaviour, then to employee outcomes (i.e., voice and withdrawal behaviour). In Study 2, we collected data from a sample of 73 team leaders and 286 employees, and the results supported the full model. Taken together, these findings offer a perspective to enrich the understanding of employee overqualification and have important practical implications.Practitioner pointsWhen leaders regard employees as overqualified, they can assist them via the means of appropriate empowerment to best utilize their skills to benefit the company.Leader empowerment can inspire employees’ voice behaviour but reduce their withdrawal behaviours.To minimize potentially negative aspects from highly overqualified employees, organizations should reduce leaders’ concern about the status threat, and encourage leaders’ proactive responses to these employees so as to achieve positive returns from overqualified employees

Comparative Synthesis: Learning Near-Optimal Network Designs by Query

When managing wide-area networks, network architects must decide how to balance multiple conflicting metrics, and ensure fair allocations to competing traffic while prioritizing critical traffic. The state of practice poses challenges since architects must precisely encode their intent into formal optimization models using abstract notions such as utility functions, and ad-hoc manually tuned knobs. In this paper, we present the first effort to synthesize optimal network designs with indeterminate objectives using an interactive program-synthesis-based approach. We make three contributions. First, we present comparative synthesis, an interactive synthesis framework which produces near-optimal programs (network designs) through two kinds of queries (Propose and Compare), without an objective explicitly given. Second, we develop the first learning algorithm for comparative synthesis in which a voting-guided learner picks the most informative query in each iteration. We present theoretical analysis of the convergence rate of the algorithm. Third, we implemented Net10Q, a system based on our approach, and demonstrate its effectiveness on four real-world network case studies using black-box oracles and simulation experiments, as well as a pilot user study comprising network researchers and practitioners. Both theoretical and experimental results show the promise of our approach