A clay-vesicle system for water purification from organic pollutants

Vesicle-clay complexes in which positively charged vesicles composed of didodecyldimethylammonium bromide (DDAB) were adsorbed on montmorillonite removed efficiently anionic (sulfentrazone, imazaquin) and neutral (alachlor, atrazine) pollutants from water. These complexes (0.5% w:w) removed 92-100% of sulfentrazone, imazaquin and alachlor and 60% of atrazine from a solution containing 10mg/L of it. A synergistic effect on the adsorption of atrazine was observed when all pollutants were present simultaneously (30 mg/L each), its percentage of removal being 85.5. Column filters (18 cm) filled with a mixture of quartz sand and vesicle-clay (100:1, w:w) were tested. For the passage of 1L (25 pore volumes) of a solution including all the pollutants at 10mg/L each, removal was complete for sulfentrazone and imazaquin, 94% for alachlor and 53.1% for atrazine, whereas removal was significantly less efficient when using activated carbon. A similar advantage of the vesicle-clay filter was observed for the capacities of removal.     

Selenium in Diketopyrrolopyrrole-based Polymers: Influence on Electronic Properties and Charge Carrier Mobilities

Diketopyrrolopyrrole (DPP)-based π-conjugated copolymers with thiophene have exceptionally high electron mobilities. This paper investigates electronic properties and charge carrier mobilities of selenophene containing analogues. Two new copolymers, with alternating thiophene DPP (TDPP) and selenophene DPP (SeDPP) units, were synthesized. Two side-chains, hexyl (Hex) and triethylene glycol (TEG) were employed, yielding polymers designated as PTDPPSeDPP-Hex and PTDPPSeDPP-TEG. Selenophene systems have smaller band gaps, with concomitant enhancement of the stability of the reduced state. For both polymers, ambipolar mobilities were observed in organic field-effect transistors (OFET). Grazing incidence X-ray diffraction (GIXD) data indicates preferential edge-on orientation of PTDPPSeDPP-TEG, which leads to superior charge transport properties of the TEG substituted polymer, as compared to its Hex analogue. Time-dependent-density functional theory (TDDFT) calculations corroborate the decrease in the optical band gap with the inclusion of selenophene. Ambipolar charge transport is rationalized by exceptionally wide conduction bands. ΔSCF calculations confirm the larger electron affinity, and therefore the greater stability, of the reduced form of the selenophene-containing DPP polymer in presence of chloroform.     

Azimuthally unidirectional transport of energy in magnetoelectric fields: topological Lenz’s effect

Magnetic-dipolar modes (MDMs) in a quasi-2D ferrite disc are microwave energy-eigenstate oscillations with topologically distinct structures of rotating fields and unidirectional power-flow circulations. At the first glance, this might seem to violate the law of conservation of an angular momentum, since the microwave structure with an embedded ferrite sample is mechanically fixed. However, an angular momentum is seen to be conserved if topological properties of electromagnetic fields in the entire microwave structure are taken into account. In this paper, we show that due to the topological action of the azimuthally unidirectional transport of energy in a MDM-resonance ferrite sample there exists the opposite topological reaction on a metal screen placed near this sample. We call this effect topological Lenz’s effect. The topological Lenz’s law is applied to opposite topological charges: one in a ferrite sample and another on a metal screen. The MDM-originated near fields – the magnetoelectric (ME) fields – induce helical surface electric currents and effective charges on a metal. The fields formed by these currents and charges will oppose their cause.     

Detecting unknown computer worm activity via support vector machines and active learning

To detect the presence of unknown worms, we propose a technique based on computer measurements extracted from the operating system. We designed a series of experiments to test the new technique by employing several computer configurations and background application activities. In the course of the experiments, 323 computer features were monitored. Four feature-ranking measures were used to reduce the number of features required for classification. We applied support vector machines to the resulting feature subsets. In addition, we used active learning as a selective sampling method to increase the performance of the classifier and improve its robustness in the presence of misleading instances in the data. Our results indicate a mean detection accuracy in excess of 90?%, and an accuracy above 94?% for specific unknown worms using just 20 features, while maintaining a low false-positive rate when the active learning approach is applied.     

The Pareto managerial principle: when does it apply?

The well-known 80/20 Pareto principle and its refinement into “A”, “B”, and “C” categories give rise to a managerial methodology consisting of three steps: classification; differentiation; and resource allocation. This is an easy-to-implement and extremely effective methodology. It starts with the creation of “Pareto diagrams”, i.e. bar charts of attributes and their relative frequency, presented in descending order. Typically, Pareto diagrams are useful in that they provide managers with a summary of practical information, revealing critical attributes. However, sometimes a Pareto diagram is less informative than it might be, because the relative frequency is almost uniform. The objective of this article is to provide an analytical tool (an index) that employs the above-mentioned methodology to measure the closeness of empirical Pareto diagrams to an “ideal” Pareto diagram. The index developed is based upon entropy.     

Conjugates of Unsaturated Fatty Acids with Propylene Glycol as Potentially Less-Irritant Skin Penetration Enhancers

Fatty acids (FA) are well known as efficient enhancers for transdermal delivery of drugs; however, their frequent dermal toxicity limits their regular use. In order to utilize the fatty acid as a safe enhancer devoid of its irritant effect, we have synthesized and evaluated a series of fatty acids conjugated to propylene glycol (FA-PG). Each one of the conjugates was prepared as a mono- or di- acyl ester derivative. The effects of the synthetic enhancers on the porcine skin permeability were evaluated in a diffusion cell system using lidocaine as the model drug. In addition, in vivo examinations in rabbits were preformed for skin toxicological evaluation. The results indicate that among the FA-PG conjugates, oleic acid (C18:1_n–9)-PG, linoleic acid (C18:2_n–6)-PG and α-linolenic acid (C18:3_n–3)-PG, mono- or di-esters, enhance the penetration of lidocaine relatively to the vehicle (without enhancer). The conjugates of oleic acid (C18:1_n–9) and linoleic acid (C18:2_n–6) with PG have demonstrated a similar enhancing effect as the corresponding free fatty acids. Interestingly, although the mono- or the di- conjugates of α-linolenic acid (C18:3_n–3) with PG enhanced the lidocaine flux as the other two fatty acid conjugates, they resulted in a reduced permeability as compared to the action of their free acid. In addition, the mono-conjugates of α-linolenic acid (C18:3_n–3) with PG exhibited elevated skin irritation in rabbits (relative to the fatty acid alone) compared to the significantly reduced irritation of oleate-PG and linoeate-PG mono-conjugates. In conclusion, except saturated FA-PG and α-linolenic acid (C18:3_n–3)—PG mono-conjugates, unsaturated fatty acids (e.g., oleic and linoleic acids) after conjugation to PG may be safe and effective enhancers for delivering topical drugs.     

A scalable lock-free stack algorithm

The literature describes two high performance concurrent stack algorithms based on combining funnels and elimination trees. Unfortunately, the funnels are linearizable but blocking, and the elimination trees are non-blocking but not linearizable. Neither is used in practice since they perform well only at exceptionally high loads. The literature also describes a simple lock-free linearizable stack algorithm that works at low loads but does not scale as the load increases. The question of designing a stack algorithm that is non-blocking, linearizable, and scales well throughout the concurrency range, has thus remained open.