Heavy Metal Sorption and Hydraulic Conductivity Studies Using Three Types of Bentonite Admixes

Bentonite, forest soil, and spruce bark were submitted to batch adsorption testing, leaching cell testing, and selective sequential extractions (SSEs) to investigate the heavy-metal compatibility of clay barriers and the potential of forest soil and spruce bark as clay barrier materials. The materials ranked as follows according to sorption capacity: forest soil > bentonite = spruce bark. The hydraulic conductivity values of heavy-metal leachates were two orders of magnitude greater than those of the blank (0.01 mol calcium nitrate) leachate. The forest soil admix ranked first in terms of heavy-metal retention capacity and breakthrough points. The mobility of Cd was 4.5 times higher than that of Pb, and Cu was 2.5 times more mobile than Pb. The leaching cell and SSE results indicate that heavy metals cause significant preferential channeling. The SSE results show that the addition of forest soil and spruce bark to clay barrier mixes promotes heavy-metal fixation.     

Hydroxy-Al pillaring of concentrated suspensions of smectite clays

The addition of solid 5/6 basic aluminum chloride salt (ACH) to a concentrated (50% w/w) acetone suspension of various dioctahedral and trioctahedral smectites, followed by washing with distilled water and centrifugation, leads to the formation of well formed pillared derivatives (PILCs). The samples were characterized by chemical analysis, X-ray diffraction, N₂ adsorption, ²⁹Si and ²⁷Al MAS NMR spectroscopy, and turned out to be highly microporous with micropore volumes in the range 0.10–0.12 cm³/g, and with highly ordered clay sheets (d₀₀₁ = 1.8 nm). The number and strength of the acid sites were estimated by analysing the product distribution of the 1-butene isomerization reaction. A mechanism of the pillaring process is proposed on the basis of MAS NMR, XRD, and N₂ adsorption data.     

A real options model for the transferability value of telecommunications licenses

Licenses for telecommunications services are awarded with a number of side obligations and commitments for the licensee. Under such obligations the licensee is typically not allowed to transfer its license to another operator. Such prohibition may cause heavy inconveniences for customers, so that its removal is strongly advocated and already a reality in many cases. Its removal adds value to the original license and may then constitute a valuable option (the transferability option). A method is here proposed to assess such value, by using the framework of real options. The method is applied in a variety of settings and shows that the value of the option depends superlinearly on the reselling price and the market volatility, and linearly or sub-linearly on the expiry time of the option.     

Object-based and environment-based inhibition of return of visual attention.

Efficient search for an object requires that attention be prevented from returning to recently examined environmental loci. M. I. Posner and Y. A. Cohen (1984) proposed that inhibition or return (IOR) of visual attention is a search mechanism that prevents such attentional perseveration. The internal representations upon which IOR functions were examined, and the following conclusions were drawn: First, IOR mechanisms have access to both object- and environment-based representations. Second, environment-based inhibition can be associated with a featureless environmental location, whereas the object-based mechanism requires that attention be oriented to a visible object. Findings are discussed in terms of physiological pathways that may mediate location- and object-based effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Geometric Modeling of Inflatable Structures for Lunar Base

A modular inflatable structure consisting of thin, composite membranes is presented for use in a lunar base. Results from a linear elastic analysis of the structure indicate that it is feasible in the lunar environment. Further analysis requires solving nonlinear equations and accurately specifying the geometries of the structural members. A computerized geometric modeling technique, using bicubic Bezier surfaces to generate the geometries of the inflatable structure, was conducted. Simulated results are used to create three‐dimensional wire frames and solid renderings of the individual components of the inflatable structure. The component geometries are connected into modules, which are then assembled based upon the desired architecture of the structure.     

A Molecular Hybrid for Mitochondria‐Targeted NO Photodelivery

The design, synthesis, spectroscopic and photochemical properties, and biological evaluation of a novel molecular hybrid that is able to deliver nitric oxide (NO) into mitochondria are reported. This molecular conjugate unites a tailored o‐CF₃‐p‐nitroaniline chromophore, for photo‐regulated NO release, and a rhodamine moiety, for mitochondria targeting, in the same molecular skeleton via an alkyl spacer. A combination of steady‐state and time‐resolved spectroscopic and photochemical experiments demonstrate that the two chromogenic units preserve their individual photophysical and photochemical properties in the conjugate quite well. Irradiation with violet light triggers NO release from the nitroaniline moiety and photoionization in the rhodamine center, which also retains considerable fluorescence efficiency. The molecular hybrid preferentially accumulates in the mitochondria of A549 lung adenocarcinoma cells where it induces toxicity at a concentration of 1 μm , exclusively upon irradiation. Comparative experiments, carried out with ad‐hoc‐synthesized model compounds, suggest that the phototoxicity observed at such a low concentration is probably not due to NO itself, but rather to the formation of the highly reactive peroxynitrite that is generated from the reaction of NO with the superoxide anion.     

Economic decision criteria for the migration to cloud storage

Cloud storage has fast become a widespread alternative to in-house costly storage infrastructures. However, the migration to cloud storage is not necessarily everybody’s best choice and should be evaluated in a rigorous quantitative way against the alternative over a long time horizon. We propose a methodological approach for the comparison of cloud vs in-house solutions, based on the use of the Net Present Value and employing stochastic models for storage prices and memory needs. We analyse two decision criteria, which employ the median and the mean value of the Differential Net Present Value (DNPV), respectively. Through three appropriate risk measures, we show that the mean DNPV is the less risky decision criterion. Since the DNPV is a stochastic quantity, we also consider a protection measure against the risk of taking the wrong decision, which relies on underwriting an insurance policy. Through the real options approach, we propose a pricing formula for such policy, showing that it is an affordable means to hedge against risk for smaller companies and over a limited time horizon. Both the decision criteria and the insurance pricing formula are applied in a typical scenario.     

Analysis of privacy in mobile telephony systems

We present a thorough experimental and formal analysis of users’ privacy in mobile telephony systems. In particular, we experimentally analyse the use of pseudonyms and point out weak deployed policies leading to some critical scenarios which make it possible to violate a user’s privacy. We also expose some protocol’s vulnerabilities resulting in breaches of the anonymity and/or user unlinkability. We show these breaches translate in actual attacks which are feasible to implement on real networks and discuss our prototype implementation. In order to countermeasure these attacks, we propose realistic solutions. Finally, we provide the theoretical framework for the automatic verification of the unlinkability and anonymity of the fixed 2G/3G procedures and automatically verify them using the ProVerif tool.     

A Potent and Selective P‐gp Modulator for Altering Multidrug Resistance Due to Pump Overexpression

P‐glycoprotein (P‐gp) is a membrane protein responsible for the active transport of several endogenous and exogenous substances. It constitutes a defense mechanism and, at the same time, it severely compromises the success rate of antitumor chemotherapy. In this study a small library of alkyl/oxyalkyl derivatives of MC70 [4′‐(6,7‐dimethoxy‐3,4‐dihydro‐1H‐isoquinolin‐2‐ylmethyl)biphenyl‐4‐ol], a well‐known P‐gp inhibitor, was synthesized through straightforward functionalization of the phenolic group present in the structure of MC70. All compounds were characterized for their effect on P‐gp, proving capable of blocking P‐gp‐mediated calcein‐AM efflux with micromolar potency, following their ability to act as high‐affinity substrates of this transporter. Excitingly, compound 4 [6,7‐dimethoxy‐2‐((4′‐butoxybiphen‐4‐yl)methyl)‐1,2,3,4‐tetrahydroisoquinoline] exhibited low nanomolar potency (5.2 nm ) and had a peculiar activity profile, acting both as a positive allosteric modulator and as a substrate of the transporter. A new and more efficient synthesis of MC70 is also described.     

Toward the preparation of a nanocomposite material through surface initiated controlled/“living” radical polymerization of styrene inside the channels of MCM-41 silica

A hybrid organic–inorganic material was prepared by surface initiated controlled/“living” radical polymerization (CRP) of styrene in the internal space of a MCM-41 silica. The inorganic precursor was synthesized, via sol–gel, using tetraethoxysilane and cetyltrimethylammonium bromide, in the presence of ammonia and ethanol to induce the formation of submicrometric spherical particles. After characterization by powder X-ray diffraction (XRD), transmission electron micrography (TEM), scanning electron micrography (SEM), N₂ adsorption and titration of the surface silanol groups, the mesoporous silica was functionalized through a 3-step grafting process, in order to link the nitroxide initiator to the inorganic matrix (TEMPO-MCM-41). The anchorage of the TEMPO-based initiator was checked by diffuse reflectance infrared spectroscopy (DRIFT-IR). Experimental data confirmed that the styrene polymerization occurred inside the MCM-41 channels system.