Effects of Acetate on Cation Exchange Capacity of a Zn-Containing Montmorillonite:Physicochemical Significance and Metal Uptake

Fundamental properties such as cation exchange capacity (CEC), permanent charge, pH(PZC), and metal uptake of a Zn-containing montmorillonite are modified, in a predictable manner, by a mild chemical treatment using acetate. Acetate treatment allows a controllable increase of the CEC of montmorillonite up to 180 mequiv/100 g. The CEC of the clay is increasing for decreasing Zn content, with a slope of Delta[Zn/Delta[CEC] approximate to -2. X-ray powder diffraction analysis shows that the lamellar structure of the clay remains unaltered by the acetate treatment, while XPS substantiates the removal of Zn. H(+) uptake data show that the intrinsic protonation pK values and concentration of the variable charge sites ( SOH) are not modified by the acetate treatment. In contrast, the concentration of the permanent charge sites ( X(-)) increased linearly with Zn removal by acetate, leading to a significant H(+) and Cd(2+) uptake enhancement. A physical model is suggested where acetate removes Zn ions strongly bound in the clay, and this in turn modulates the permanent charge and the CEC of the clay

Stochastically Consistent Caching and Dynamic Duty Cycling for Erratic Sensor Sources

We present a novel dynamic duty cycling scheme to maintain stochastic consistency for caches in sensor networks. To reduce transmissions, base stations often maintain caches for erratically changing sensor sources. Stochastic consistency guarantees the cache-source deviation is within a pre-specified bound with a certain confidence level. We model the erratic sources as Brownian motions, and adaptively {\it predict} the next cache update time based on the model. By piggybacking the next update time in each regular data packet, we can dynamically adjust the relaying nodes' duty cycles so that they are awake before the next update message arrives, and are sleeping otherwise. Through simulations, we show that our approach can achieve very high source-cache fidelity with low power consumption on many real-life sensor data. On average, our approach consumes 4-5 times less power than GAF~\cite{gaf}, and achieves 50\% longer network lifetime

Pythagoras project: Development of an innovative training package on Indoor Environment Quality

The aim of the Pythagoras project is the development and assessment of Greek national training material in the sector of indoor environmental quality. The need for education in this specific sector is dictated by the significant indoor environment deterioration and associated health hazards, which are caused by low ventilation levels, combined with the use of many modern building materials that aggravate pollutants emissions. Early in the project, a review is undertaken of the international literature and the syllabuses of foreign research and educational institutions active in indoor environment quality issues. At the same time, the requirements of the Greek educational and broader society, related to issues of indoor pollution and health, are determined. A training methodology is consequently developed, with the objective to optimally cover all the parameters associated with the indoor environment quality, for trainees of various disciplines. The training material is produced both in printed (book) and integrated electronic (e-learning) format. Additionally, four seminars are organized covering the respective sections of the training package. The training package is being assessed both by the trainees but also by international experts in the sector of indoor environment quality

Coping with floods: impacts, preparedness and resilience capacity of Greek micro-, small- and medium-sized enterprises in flood-affected areas

Purpose: This paper aims to investigate aspects of flood experience, attitudes and responses of micro-, small- and medium-sized enterprises (MSMEs) in Greece and to indicate a typology of strategies associated with their relative effort to build flood resilience capacity. Design/methodology/approach: A qualitative study protocol was used, based on pertinent literature that considers how business entities withstand, adapt and/or recover from non-linear climate change impacts, natural hazards and extreme weather. Data was obtained by conducting semi-structured interviews with 82 MSMEs’ owners-managers who had recently experienced flooding. Findings: The study reports limited activities of MSMEs towards flood resilience capacity despite the threat of relevant disasters. Findings suggest that most owners-managers of these enterprises are not adequately preparing their businesses for the impacts of flooding. Research limitations/implications: The findings call for multi-level and dynamic perspectives to be examined in assessing MSME resilience capacity to floods. It is attitudinal, managerial, organisational, behavioural and regulatory (as well as other institutional) factors that merit further investigation. Such an investigation would allow a better understanding as to whether these factors hinder or enable conditions for microeconomic flood preparedness and resilience as well as how they may interact with each other or create feedback loops. Practical implications: The study carries managerial implications and policy recommendations in terms of nurturing opportunities towards awareness-raising campaigns for reducing deficits in managerial knowledge and competencies. It also encapsulates practical implications in terms of emphasising supporting mechanisms from key institutional stakeholders to allow MSMEs scan available options they have in effectively reinforcing the business premises from the forces of rising waters. Originality/value: Most of the related studies have examined flood impacts, responses and/or resilience capacity at the household- or community-level. Empirical work that is conducted to ascertain how MSMEs cope with flooding remains thin on the ground. In response to this, the current study and the typology of MSMEs’ strategic postures that are suggested seek to contribute to this under-researched topic

The polymer phase of the TDAE-C60_{60} organic ferromagnet

The high-pressure Electron Spin Resonance (ESR) measurements were preformed on TDAE-C$_{60}$ single crystals and stability of the polymeric phase was established in the $P - T$ parameter space. At 7 kbar the system undergoes a ferromagnetic to paramagnetic phase transition due to the pressure-induced polymerization. The polymeric phase remains stable after the pressure release. The depolymerization of the pressure-induced phase was observed at the temperature of 520 K. Below room temperature, the polymeric phase behaves as a simple Curie-type insulator with one unpaired electron spin per chemical formula. The TDAE$^+$ donor-related unpaired electron spins, formerly ESR-silent, become active above the temperature of 320 K and the Curie-Weiss behavior is re-established.Comment: Submitted to Phys. Rev.

Optical anisotropy in type-II ZnTe/ZnSe submonolayer quantum dots

Linearly polarized photoluminescence is observed for type-II ZnTe/ZnSe submonolayer quantum dots (QDs). The comparison of spectral dependence of the degree of linear polarization (DLP) among four samples indicates that the optical anisotropy is mostly related to the elongation of ZnTe QDs. Numerical calculations based on the occupation probabilities of holes in px and py orbitals are performed to estimate the lateral aspect ratio of the QDs, and it is shown that it varies between 1.1 and 1.4. The value of anisotropic exchange splitting for bright excitonic states is found to be ∼200 μeV from the measurement of the degree of circular polarization as a function of the magnetic field. The results also show that heavy-light hole mixing ratio is about 0.16

Alzheimer's Aβ Peptides with Disease-Associated N-Terminal Modifications: Influence of Isomerisation, Truncation and Mutation on Cu2+ Coordination

coordination of various Aβ peptides has been widely studied. A number of disease-associated modifications involving the first 3 residues are known, including isomerisation, mutation, truncation and cyclisation, but are yet to be characterised in detail. In particular, Aβ in plaques contain a significant amount of truncated pyroglutamate species, which appear to correlate with disease progression. coordination modes between pH 6–9 with nominally the same first coordination sphere, but with a dramatically different pH dependence arising from differences in H-bonding interactions at the N-terminus. coordination of Aβ, which may be critical for alterations in aggregation propensity, redox-activity, resistance to degradation and the generation of the Aβ3–× (× = 40/42) precursor of disease-associated Aβ3[pE]–x species

Hierarchically compressed wavelet synopses

The wavelet decomposition is a proven tool for constructing concise synopses of large data sets that can be used to obtain fast approximate answers. Existing research studies focus on selecting an optimal set of wavelet coefficients to store so as to minimize some error metric, without however seeking to reduce the size of the wavelet coefficients themselve

Bandwidth-constrained queries in sensor networks

Sensor networks consist of battery-powered wireless devices that are required to operate unattended for long periods of time. Thus, reducing energy drain is of utmost importance when designing algorithms and applications for such networks. Aggregate queries are often used by monitoring applications to assess the status of the network and detect abnormal behavior. Since radio transmission often constitutes the biggest factor of energy drain in a node, in this paper we propose novel algorithms for the evaluation of bandwidth- constrained queries over sensor networks. The goal of our techniques is, given a target bandwidth utilization factor, to program the sensor nodes in a way that seeks to maximize the accuracy of the produced query results at the monitoring node, while always providing strong error guarantees to the monitoring application. This is a distinct difference of our framework from previous techniques that only provide probabilistic guarantees on the accuracy of the query result. Our algorithms are equally applicable when the nodes have ample power resources, but bandwidth consumption needs to be minimized, for instance in densely distributed networks, to ensure proper operation of the nodes. Our experiments with real sensor data show that bandwidth-constrained queries can substantially reduce the number of messages in the network while providing very tight error bounds on the query result. © 2006 Springer-Verlag