Electrophoretic mobility of magnetite particles in high temperature water

Magnetite (Fe₃O₄) is one of the most common oxides forming deposits and particulate phases in industrial high temperature water circuits. Its colloidal characteristics play a principal role in the mechanism of deposit formation and can be used as controlling factors to prevent or minimize deposit formation and damage of industrial pipelines due to under-deposit corrosion. In this study, a high temperature particle electrophoresis technique was employed to measure the zeta potential at the magnetite/water interface—the parameter that controls colloidal stability of particles, their aggregation, and deposition. The measurements were made at temperatures up to 200 °C over a wide range of pH. The isoelectric points of magnetite, at which the deposition of particles is increased, were determined at pH 6.35, 6.00, 5.25, and 5.05 for temperatures 25, 100, 150, and 200 °C, respectively. The observed temperature dependence of zeta potential and the isoelectric pH point of magnetite can help to explain the extent of interactions between the colloidal particles and the steel wall surfaces under hydrothermal conditions, and indicate methods for controlling and mitigating oxide deposition in high temperature water cycles.     

Analysis of the electrochemical reactivity of natural hemozoin and β-hemozoin in the presence of antimalarial drugs

We report an evaluation of the reactivity of hemozoin (HZ) and β-hemozoin (β-HZ) obtained from the Triatoma Meccus longipennis, alone and in combination with quinine and amodiaquine. Using cyclic voltammetry and carbon paste electrodes, the redox processes that these compounds undergo were analysed. The results indicated that the atom Fe presence, the substance concentration, the drugs existence and the nature of the electrolytic medium are important in the redox processes. The strongest reactivity was for β-HZ from Triatoma, which suggests that cellular molecules are embedded in an oxidising environment due to the presence of β-HZ and indicates that like HZ, β-HZ could be associate with phospholipid bilayers and interfere with their physical and chemical integrity, contributing to membrane breakdown and hyper-oxidation of molecules. It was further observed that when measuring the reactivity of HZ and β-HZ with quinine and amodiaquine, a more oxidative stress was generated between the second one and the β-HZ, which could explain the effectiveness of amodiaquine as a better antimalarial drug. Finally, it was concluded that electrochemical evaluation may be a convenient tool in determining the efficiency of antimalarial drugs and the identification of their redox processes.     

CO2 sequestration in coals and enhanced coalbed methane recovery: New numerical approach

Mixed gases injection into a large coal sample for CO₂ sequestration in coals and enhanced coalbed methane recovery was investigated using a new numerical approach. A dynamic multi-component transport (DMCT) model was applied to simulate ternary gas (CH₄-CO₂-N₂) diffusion and flow behaviors for better understanding and prediction of gas injection enhanced coalbed methane (ECBM) recovery processes. Several cases were designed to analyze the effects of injection gas composition and pressure on gas displacement dynamics in a large coal sample. The calculated results suggest that mixed gas injections have similar profiles of methane recovery as pure N₂ injection, and mixtures of N₂ and CO₂ reduce the ultimate methane recovery compared to pure CO₂. The breakthrough time of pure CO₂ injection is longer than mixed gas injections. Injection gas composition has significant effect on produced gas composition.     

Pd catalysts immobilized onto gel-supported ionic liquid-like phases (g-SILLPs): A remarkable effect of the nature of the support

New polymeric materials containing functional sites analogous to ionic liquids have been synthesized. Those materials are a supported reservoir for the active Pd species. Their catalytic activity has been evaluated for the Heck reaction proving an excellent performance in terms of both activity and recyclability. Although soluble Pd species seem to participate in the catalytic cycle, as for many other supported Pd-systems, the g-SILLPs present the ability to efficiently release and recapture those soluble species. This allows to dramatically reduce or eliminate the amount of Pd leached to the final solution, in particular at higher temperatures, and opens the way, based on a release and catch strategy, for the development of active-supported Pd catalytic systems, easily recoverable and reusable for a large number of catalytic cycles. The exact nature of the polymer (SILLPs) has a remarkable influence on the overall process. The appropriate design of the g-SILLPs is a key factor for the optimization of the release and catch system. The functionalized polymers prepared can be reused for a significant number of catalytic cycles without any loss in performance.     

Electromechanical self-oscillations of carbon nanotube field emitter

We report the observation of the electromechanical self-oscillations excited in a vacuum diode with a field emission cathode made of single-wall carbon nanotubes. The mechanical oscillations of the cathode accompanied by the periodic variations of the emission current intensity have been observed under the action of a constant voltage applied between the cathode and the anode of the diode. An empirical model of the phenomenon is proposed. It provides a qualitative agreement of the experimental results and the theoretical predictions. The modeling assuming a common behavior of the electromechanical systems with nano-sized mechanically flexible field emitters has been performed. It has demonstrated a dependence of the oscillation frequency value on the geometrical size of flexible emitters and on the value of voltage applied. This phenomenon opens a way for generation of the high frequency electromagnetic waves by using the electromechanical systems with emitters of nanometer size.     

Oxidative Stress Mediates the Disruption of Airway Epithelial Tight Junctions through a TRPM2-PLCγ1-PKCα Signaling Pathway

Oxidative stress has been implicated as an important contributing factor in the pathogenesis of several pulmonary inflammatory diseases. Previous studies have indicated a relationship between oxidative stress and the attenuation of epithelial tight junctions (TJs). In Human Bronchial Epithelial-16 cells (16HBE), we demonstrated the degradation of zonula occludens-1 (ZO-1), and claudin-2 exhibited a great dependence on the activation of the transient receptor potential melastatin (TRPM) 2 channel, phospholipase Cγ1 (PLCγ1) and the protein kinase Cα (PKCα) signaling cascade.     

The chemical structure of the amorphous phase of propylene–ethylene random copolymers in relation to their stress–strain properties

A better understanding of structure-property relations is necessary to design novel materials. In this study, we investigate the morphology and chemical structure of five commercial grades of propylene-based polymers in relation to the change in yield- stress as a function of strain-rate. Substantial emphasis has been laid on understanding the chain microstructure in the relation to chain dynamics in the amorphous phase. Heterogeneous Ziegler–Natta catalysis was used to prepare the samples with differing ratios of propylene and ethylene units. Various analytical techniques such as WAXS, SAXS, solution- and solid-state NMR were employed to characterize their structure. The results indicate a reduction in crystallinity, melting temperature, long-period and crystal thickness with increasing ethylene content. Solid-state NMR data reveal the presence of four components in these samples, which is an extension of the traditional three phase model found in most semi-crystalline polymers. The additional fourth phase is attributed to a rubber-like component that is primarily composed of chain segments rich in ethylene units and shows an increase in chain dynamics with increasing ethylene content in the samples. Mechanical experiments show that yield stress decreases with increase in the amount ethylene which can be correlated to the observed increase in chain dynamics in the amorphous phase.     

Multi-layer atom chips for atom tunneling experiments near the chip surface

This paper describes the design and fabrication of an atom chip to be used in ultra-high-vacuum cells for cold-atom tunneling experiments. A fabrication process was developed to pattern micrometer- and nanometer-scale copper wires onto a single chip. The wires, with fabricated widths down to 200 nm, can sustain current densities of more than 7.5 × 10⁷ A/cm². Partially suspended wires, developed in order to reduce the Casimir–Polder force between atoms and surface, were also fabricated and tested. Extensive measurements for variable wire width show that the sustainable currents are sufficiently large to allow chip-based atom tunneling experiments. Such chips may allow the realization of an atom transistor.     

The socio-political economy of nuclear power development in Japan and South Korea

This paper analyzes the socio-cultural, political and economic conditions prevalent during the inception of nuclear power programs in Japan and South Korea in order to identify commonalities which support nuclear power program expansion. The study identifies six factors as having a clear influence on supporting nuclear power development: (1) strong state involvement in guiding economic development; (2) centralization of national energy policymaking and planning; (3) campaigns to link technological progress with national revitalization; (4) influence of technocratic ideology on policy decisions; (5) subordination of challenges to political authority, and (6) low levels of civic activism. The paper postulates that insights from this study can be used to assess the propensity of nations which have the emergent capacity to support nuclear power development to actually embark on such programs.     

Let's inhibit our excitement: The relationships between Stroop, behavioral disinhibition, and the frontal lobes.

Objective: The Stroop (Stroop, 1935) is a frequently used neuropsychological test, with poor performance typically interpreted as indicative of disinhibition and frontal lobe damage. This study tested those interpretations by examining relationships between Stroop performance, behavioral disinhibition, and frontal lobe atrophy. Method: Participants were 112 patients with mild cognitive impairment or dementia, recruited through UCSF's Memory and Aging Center. Participants received comprehensive dementia evaluations including structural MRI, neuropsychological testing, and informant interviews. Freesurfer, a semiautomated parcellation program, was used to analyze 1.5T MRI scans. Behavioral disinhibition was measured using the Neuropsychiatric Inventory (Cummings, 1997; Cummings et al., 1994) Disinhibition Scale. The sample (n = 112) mean age was 65.40 (SD = 8.60) years, education was 16.64 (SD = 2.54) years, and Mini-Mental State Examination (MMSE; Folstein et al., 1975) was 26.63 (SD = 3.32). Hierarchical linear regressions were used for data analysis. Results: Controlling for age, MMSE, and color naming, Stroop performance was not significantly associated with disinhibition (β = 0.01, ΔR2 = 0.01, p = .29). Hierarchical regressions controlling for age, MMSE, color naming, intracranial volume, and temporal and parietal lobes, examined whether left or right hemisphere regions predict Stroop performance. Bilaterally, parietal lobe atrophy best predicted poorer Stroop (left: β = 0.0004, ΔR2 = 0.02, p = .002; right: β = 0.0004, ΔR2 = 0.02, p = .002). Of frontal regions, only dorsolateral prefrontal cortex atrophy predicted poorer Stroop (β = 0.001, ΔR2 = 0.01, p = .03); left and right anterior cingulate cortex atrophy predicted better Stroop (left: β = ?0.003, ΔR2 = 0.01, p = .02; right: β = ?0.004, ΔR2 = 0.01, p = .02). Conclusion: These findings suggest Stroop performance is a poor measure of behavioral disinhibition and frontal lobe atrophy even among a relatively high-risk population. (PsycINFO Database Record (c) 2011 APA, all rights reserved)