Equilibrium and kinetics of copper extraction from ammoniacal solutions by hydroxoximes with particular emphasis on transport phenomena

Journal ArticleThe chemistry of copper extraction from ammoniacal solutions by hydroxyoxime extractants was studied. Equilibrium measurements were made by shakeout experiments with subsequent analyasis of the aqueous and/or organic phases. The kinetic experiments were carried out in a single drop reaction cell in order to establish the details of the intrinsic reaction kinetics for this system

Material Versatility Using Replica Molding for Large-Scale Fabrication of High Aspect-Ratio, High Density Arrays of Nano-Pillars

Arrays of high aspect-ratio (AR) nano-pillars have attracted a lot of interest for various applications, such as for use in solar cells, surface acoustic sensors, tissue engineering, bio-inspired adhesives and anti-reflective surfaces. Each application may require a different structural material, which can vary in the required chemical composition and mechanical properties. In this paper, a low cost fabrication procedure is proposed for large scale, high AR and high density arrays of nano-pillars. The proposed method enables the replication of a master with high fidelity, using the subsequent replica molds multiple times, and preparing arrays of nano-pillars in a variety of different materials. As an example applied to bio-inspired dry adhesion, polymeric arrays of nano-pillars are prepared in this work. Thermoset and thermoplastic nano-pillar arrays are examined using an atomic force microscope to assess their adhesion strength and its uniformity. Results indicate the proposed method is robust and can be used to reliably prepare nano-structures with a high AR

Stamp transferred suspended graphene mechanical resonators for radio-frequency electrical readout

We present a simple micromanipulation technique to transfer suspended graphene flakes onto any substrate and to assemble them with small localized gates into mechanical resonators. The mechanical motion of the graphene is detected using an electrical, radio-frequency (RF) reflection readout scheme where the time-varying graphene capacitor reflects a RF carrier at f=5-6 GHz producing modulation sidebands at f +/- fm. A mechanical resonance frequency up to fm=178 MHz is demonstrated. We find both hardening/softening Duffing effects on different samples, and obtain a critical amplitude of ~40 pm for the onset of nonlinearity in graphene mechanical resonators. Measurements of the quality factor of the mechanical resonance as a function of DC bias voltage Vdc indicate that dissipation due to motion-induced displacement currents in graphene electrode is important at high frequencies and large Vdc

Results from the fly’s eye experiment

We report recently analyzed results on the energy spectrum, and composition of cosmic rays above 0.3 EeV. We observe a break in the spectrum at 3 EeV and a changing composition. The results can be explained by a simple two component model: galactic cosmic rays dominated by heavy primaries and an extragalactic component dominated by light primaries. The observed isotropic arrival direction distribution is consistent with the predictions of this model. A 320 EeV event was also recorded. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87516/2/839_1.pd

Macroautophagy—a novel β-amyloid peptide-generating pathway activated in Alzheimer's disease

Macroautophagy, which is a lysosomal pathway for the turnover of organelles and long-lived proteins, is a key determinant of cell survival and longevity. In this study, we show that neuronal macroautophagy is induced early in Alzheimer's disease (AD) and before β-amyloid (Aβ) deposits extracellularly in the presenilin (PS) 1/Aβ precursor protein (APP) mouse model of β-amyloidosis. Subsequently, autophagosomes and late autophagic vacuoles (AVs) accumulate markedly in dystrophic dendrites, implying an impaired maturation of AVs to lysosomes. Immunolabeling identifies AVs in the brain as a major reservoir of intracellular Aβ. Purified AVs contain APP and β-cleaved APP and are highly enriched in PS1, nicastrin, and PS-dependent γ-secretase activity. Inducing or inhibiting macroautophagy in neuronal and nonneuronal cells by modulating mammalian target of rapamycin kinase elicits parallel changes in AV proliferation and Aβ production. Our results, therefore, link β-amyloidogenic and cell survival pathways through macroautophagy, which is activated and is abnormal in AD

Evidence for Changing of Cosmic Ray Composition between 10\u3csup\u3e17\u3c/sup\u3e and 10\u3csup\u3e18\u3c/sup\u3e eV from Multicomponent Measurements

The average mass composition of cosmic rays with primary energies between 1017 and 1018eV has been studied using a hybrid detector consisting of the High Resolution Fly\u27s Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases. © 2000 The American Physical Society

Extracellular Tau Oligomers Produce An Immediate Impairment of LTP and Memory

Non-fibrillar soluble oligomeric forms of amyloid-\u3b2 peptide (oA\u3b2) and tau proteins are likely to play a major role in Alzheimer's disease (AD). The prevailing hypothesis on the disease etiopathogenesis is that oA\u3b2 initiates tau pathology that slowly spreads throughout the medial temporal cortex and neocortices independently of A\u3b2, eventually leading to memory loss. Here we show that a brief exposure to extracellular recombinant human tau oligomers (oTau), but not monomers, produces an impairment of long-term potentiation (LTP) and memory, independent of the presence of high oA\u3b2 levels. The impairment is immediate as it raises as soon as 20\u2009min after exposure to the oligomers. These effects are reproduced either by oTau extracted from AD human specimens, or naturally produced in mice overexpressing human tau. Finally, we found that oTau could also act in combination with oA\u3b2 to produce these effects, as sub-toxic doses of the two peptides combined lead to LTP and memory impairment. These findings provide a novel view of the effects of tau and A\u3b2 on memory loss, offering new therapeutic opportunities in the therapy of AD and other neurodegenerative diseases associated with A\u3b2 and tau pathology