Novel conducting polymer current limiting devices for low cost surge protection applications

We report on the development of novel intrinsic conducting polymer two terminal surge protection devices. These resettable current limiting devices consist of polyaniline nanofibres doped with methane sulphonic acid electrochemically deposited between two 55 μm spaced gold electrodes. At normal applied voltages, the low resistance devices act as passive circuit elements, not affecting the current flow. However during a current surge the devices switch from ohmic to non-ohmic behaviour, limiting current through the device. After the current surge has passed, the devices reset back to their original state. Our studies show that a partial de-doping/re-doping process caused by the rapid diffusion of moisture out of or into the polymer film during joule heating/cooling is the underlying mechanism responsible

Higher-dimensional multifractal value sets for conformal infinite graph directed Markov systems

We give a description of the level sets in the higher dimensional multifractal formalism for infinite conformal graph directed Markov systems. If these systems possess a certain degree of regularity this description is complete in the sense that we identify all values with non-empty level sets and determine their Hausdorff dimension. This result is also partially new for the finite alphabet case.Comment: 20 pages, 1 figur

Zinc Phosphide Residues in Gray-Tailed Voles (\u3ci\u3eMicrotus canicaudus\u3c/i\u3e) Fed Fixed Particles of a 2% Grain Bait

This study measured depelted-carcass residues of zinc phosphide (Zn3P2, CAS # 1314-84-7) in 8 (4 males and 4 females) gray-tailed voles (Microtus canicaudus). Six (3 males and 3 females) voles were confined individually in 1.89 dkl (5 gal) plastic pails that contained 5,2% Zn3P2 steamrolled- oat (SRO) groats; 2 voles (1 male and 1 female) served as analytical (unbaited) controls. Four test voles (3 males and 1female) died within 7.5 h after bait exposure; whereas, 2 test voles showed no signs of toxicosis and were euthanized 7.0 h after bait exposure. Whole carcasses were stored frozen and depelted carcasses were analyzed within 31 days for Zn3P2 residues using a acid-hydrolyzation, gas-chromatographic (GC) method. Analytical controls were euthanized, with carcasses stored and analyzed the same as test voles. A mean (± SD) 4.7 (±0.8) SRO groats were consumed by the test voles; this converted to a mean (±SD) intake of 2.15 (±0.38) mg Zn3P2 and dose of 73.25 mg/kg ( ± 22.95) Zn3P2. The mean (± SD) Zn3P2 residue in the 6 test vole carcasses was 0.42 mg (± 0.68); control carcasses contained \u3c0.009 mg Zn3P2- 3P2 in voles are variable, but typically \u3c 50% of ingested rodenticide and (2) risks of secondary poisoning posed by Zn3P2-baited voles to avian and mammalian predators/scavengers are low due to the relatively high toxic thresholds (\u3e 20 mg/kg) required to affect these species

‘It Relates to My Everyday Life.’ Critical Pedagogy and Student Explanations of Interest in Sociology Course Topics

We applied critical pedagogy in the college classroom by asking students what topics they would want covered in their Introduction to Sociology courses if they were given the power to decide. Students were also asked to explain why they were interested, and uninterested, in learning about the topics they chose from our questionnaire. Survey data was collected from 191 students at a southeastern community college; the majority were not sociology majors. Overall, students were the most interested in learning about culture, deviance, race, and gender issues. Students were the least interested in learning about topics concerning urbanization and the economy. We found that students are typically interested in topics that are related to general curiosities or are applicable to the students’ personal lives or future careers. However, students were vaguer in their responses regarding why they were uninterested in learning about particular sociological topics; most students claimed that they were simply “just uninterested.” These results support the claim that a student’s desire to learn material is guided by how personally invested he or she is in the topic. By implementing a critical pedagogical teaching approach in the classroom, professors could increase student interest, thus fostering more successful and satisfied students

Large dopant dependence of the current limiting properties of intrinsic conducting polymer surge protection devices

New two terminal surge protection devices based on intrinsic conducting polymers are demonstrated to be strongly affected by the dopant molecule type. Thermogravimetric analysis combined with current–voltage studies show a causal link between the dopant molecule, moisture content and the current limiting capability of the devices. Polyaniline thin-films with high moisture content produce devices with current saturation and foldback effects at high applied voltages while low moisture content films exhibit no current rectification and instead demonstrate decreasing resistivity with increasing voltage. Polyaniline doped with sulfuric acid (H2SO4) exhibited the largest moisture content and surge protection devices built with this material produced for the first time negative differential resistance under ambient conditions. A further improvement was made upon this through surface engineering of the interface between the polymer and electrodes using self-assembled monolayers

Enhancement of atmospheric H2SO4/H2O nucleation: Organic oxidation products versus amines

Atmospheric H2SO4 / H2O nucleation influencing effects have been studied in the flow tube IfT-LFT (Institute for Tropospheric Research – Laminar Flow Tube) at 293 ± 0.5 K and a pressure of 1 bar using synthetic air as the carrier gas. The presence of a possible background amine concentration in the order of 107–108 molecule cm−3 throughout the experiments has to be taken into account. In a first set of investigations, ozonolysis of olefins (tetramethylethylene, 1-methyl-cyclohexene, α-pinene and limonene) for close to atmospheric concentrations, served as the source of OH radicals and possibly other oxidants initiating H2SO4 formation starting from SO2. The oxidant generation is inevitably associated with the formation of organic oxidation products arising from the parent olefins. These products (first generation mainly) showed no clear effect on the number of nucleated particles within a wide range of experimental conditions for H2SO4 concentrations higher than ~107 molecule cm−3. Also the early growth process of the nucleated particles was not significantly influenced by the organic oxidation products in line with the expected growth by organic products using literature data. An additional, H2SO4-independent process of particle (nano-CN) formation was observed in the case of α-pinene and limonene ozonolysis for H2SO4 concentrations smaller than ~107 molecule cm−3. Furthermore, the findings confirm the appearance of an additional oxidant for SO2 beside OH radicals, very likely stabilized Criegee Intermediates (sCI). A second set of experiments has been performed in the presence of added amines in the concentrations range of a few 107–1010 molecule cm−3 applying photolytic OH radical generation for H2SO4 production without addition of other organics. All amines showed significant nucleation enhancement with increasing efficiency in the order pyridine < aniline < dimethylamine < trimethylamine. This result supports the idea of H2SO4 cluster stabilization by amines due to strong H2SO4↔amine interactions. On the other hand, this study indicates that for organic oxidation products (in presence of the possible amine background as stated) a distinct H2SO4 / H2O nucleation enhancement can be due to increased H2SO4 formation caused by additional organic oxidant production (sCI) rather than by stabilization of H2SO4 clusters due to H2SO4↔organics interactions

Super hydrophobic SAM modified electrodes for enhanced current limiting properties in intrinsic conducting polymer surge protection devices

Surface interface engineering using superhydrophobic gold electrodes made with 1-dodecanethiol self-assembled monolayer (SAM) has been used to enhance the current limiting properties of novel surge protection devices based on the intrinsic conducting polymer, polyaniline doped with methanesulfonic acid. The resulting devices show significantly enhanced current limiting characteristics, including current saturation, foldback, and negative differential effects. We show how SAM modification changes the morphology of the polymer film directly adjacent to the electrodes, leading to the formation of an interfacial compact thin film that lowers the contact resistance at the Au−polymer interface. We attribute the enhanced current limiting properties of the devices to a combination of lower contact resistance and increased Joule heating within this interface region which during a current surge produces a current blocking resistive barrier due to a thermally induced dedoping effect caused by the rapid diffusion of moisture away from this region. The effect is exacerbated at higher applied voltages as the higher temperature leads to stronger depletion of charge carriers in this region, resulting in a negative differential resistance effec

Phase transitions for suspension flows

This paper is devoted to study thermodynamic formalism for suspension flows defined over countable alphabets. We are mostly interested in the regularity properties of the pressure function. We establish conditions for the pressure function to be real analytic or to exhibit a phase transition. We also construct an example of a potential for which the pressure has countably many phase transitions.Comment: Example 5.2 expanded. Typos corrected. Section 6.1 superced the note "Thermodynamic formalism for the positive geodesic flow on the modular surface" arXiv:1009.462

Natural equilibrium states for multimodal maps

This paper is devoted to the study of the thermodynamic formalism for a class of real multimodal maps. This class contains, but it is larger than, Collet-Eckmann. For a map in this class, we prove existence and uniqueness of equilibrium states for the geometric potentials $-t \log|Df|$, for the largest possible interval of parameters $t$. We also study the regularity and convexity properties of the pressure function, completely characterising the first order phase transitions. Results concerning the existence of absolutely continuous invariant measures with respect to the Lebesgue measure are also obtained

Quantum correlations in Newtonian space and time: arbitrarily fast communication or nonlocality

We investigate possible explanations of quantum correlations that satisfy the principle of continuity, which states that everything propagates gradually and continuously through space and time. In particular, following [J.D. Bancal et al, Nature Physics 2012], we show that any combination of local common causes and direct causes satisfying this principle, i.e. propagating at any finite speed, leads to signalling. This is true even if the common and direct causes are allowed to propagate at a supraluminal-but-finite speed defined in a Newtonian-like privileged universal reference frame. Consequently, either there is supraluminal communication or the conclusion that Nature is nonlocal (i.e. discontinuous) is unavoidable.Comment: It is an honor to dedicate this article to Yakir Aharonov, the master of quantum paradoxes. Version 2 contains some more references and a clarified conclusio