974 resultados para EXPERIMENTAL STORAGE-RING


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Parkinson s disease (PD) is a neurodegenerative disorder associated with a progressive loss of dopaminergic neurons of the substantia nigra (SN). Current therapies of PD do not stop the progression of the disease and the efficacy of these treatments wanes over time. Neurotrophic factors are naturally occurring proteins promoting the survival and differentiation of neurons and the maintenance of neuronal contacts. Neurotrophic factors are attractive candidates for neuroprotective or even neurorestorative treatment of PD. Thus, searching for and characterizing trophic factors are highly important approaches to degenerative diseases. CDNF (cerebral dopamine neurotrophic factor) and MANF (mesencephalic astrocyte-derived neurotrophic factor) are secreted proteins that constitute a novel, evolutionarily conserved neurotrophic factor family expressed in vertebrates and invertebrates. The present study investigated the neuroprotective and restorative effects of human CDNF and MANF in rats with unilateral partial lesion of dopamine neurons by 6-hydroxydopamine (6-OHDA) using both behavioral (amphetamine-induced rotation) and immunohistochemical analyses. We also investigated the distribution and transportation profiles of intrastriatally injected CDNF and MANF in rats. Intrastriatal CDNF and MANF protected nigrostriatal dopaminergic neurons when administered six hours before or four weeks after the neurotoxin 6-OHDA. More importantly, the function of the lesioned nigrostriatal dopaminergic system was partially restored even when the neurotrophic factors were administered four weeks after 6-OHDA. A 14-day continuous infusion of CDNF but not of MANF restored the function of the midbrain neural circuits controlling movement when initiated two weeks after unilateral injection of 6-OHDA. Continuous infusion of CDNF also protected dopaminergic TH-positive cell bodies from toxin-induced degeneration in the substantia nigra pars compacta (SNpc) and fibers in the striatum. When injected into the striatum, CDNF and GDNF had similar transportation profiles from the striatum to the SNpc; thus CDNF may act via the same nerve tracts as GDNF. Intrastriatal MANF was transported to cortical areas which may reflect a mechanism of neurorestorative action that is different from that of CDNF and GDNF. CDNF and MANF were also shown to distribute more readily than GDNF. In conclusion, CDNF and MANF are potential therapeutic proteins for the treatment of PD.

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We report the quasielastic neutron scattering (QENS) and molecular dynamics (MD) investigations into diffusion of pentane isomers in zeolite NaY. The molecular cross section perpendicular to the long molecular axis varies for the three isomers while the mass and the isomer-zeolite interaction remains essentially unchanged. Both QENS and MD results show that the branched isomers neopentane and isopentane have higher self-diffusivities as compared with n-pentane at 300 K in NaY zeolite. This result provides direct experimental evidence for the existence of nonmonotonic, anomalous dependence of self-diffusivity on molecular diameter known as the levitation effect. The energetic barrier at the bottleneck derived from MD simulations exists for n-pentane which lies in the linear regime while no such barrier is seen for neopentane which is located clearly in the anomalous regime.Activation energy is in the order E-a(n-pentane)>E-a(isopentane)>E-a(neopentane) consistent with the predictions of the levitation effect. In the liquid phase, it is seen thatD(n pentane)>D(isopentane)>D(neopentane) and E-a(n-pentane)< E-a(isopentane)< E-a(neopentane). Intermediate scattering function for small wavenumbers obtained from MD follows a single exponential decay for neopentane and isopentane. For n-pentane, a single exponential fit provides a poor fit especially at short times. Cage residence time is largest for n-pentane and lowest for neopentane. For neopentane, the width of the self-part of the dynamic structure factor shows a near monotonic decrease with wavenumber. For n-pentane a minimum is seen near k=0.5 A degrees(-1) suggesting a slowing down of motion around the 12-ring window, the bottleneck for diffusion. Finally, the result that the branched isomer has a higher diffusivity as compared with the linear analog is at variation from what is normally seen.

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A theory and generalized synthesis procedure is advocated for the design of weir notches and orifice-notches having a base in any given shape, to a depth a, such that the discharge through it is proportional to any singular monotonically-increasing function of the depth of flow measured above a certain datum. The problem is reduced to finding an exact solution of a Volterra integral equation in Abel form. The maximization of the depth of the datum below the crest of the notch is investigated. Proof is given that for a weir notch made out of one continuous curve, and for a flow proportional to the mth power of the head, it is impossible to bring the datum lower than (2m − 1)a below the crest of the notch. A new concept of an orifice-notch, having discontinuity in the curve and a division of flow into two distinct portions, is presented. The division of flow is shown to have a beneficial effect in reducing the datum below (2m − 1)a from the crest of the weir and still maintaining the proportionality of the flow. Experimental proof with one such orifice-notch is found to have a constant coefficient of discharge of 0.625. The importance of this analysis in the design of grit chambers is emphasized.

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The problem of a two-layer circular cylindrical shell subjected to radial ring loading has been solved theoretically. The solution is developed by uniting the elasticity solution through Love function approach for the inner thick shell with the Flügge shell theory for the thin outer shell. Numerical work has been done with a digital computer for different values of shell geometry parameters and material constants. The general behaviour of the composite shell has been studied in the light of these numerical results.

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A semi-experimental approach to solve two-dimensional problems in elasticity is given. The method has been applied to two problems, (i) a square deep beam, and (ii) a bridge pier with a sloping boundary. For the first problem sufficient analytical results are available and hence the accuracy of the method can be verified. Then the method has been extended to the second problem for which sufficient results are not available.

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The problem is solved using the Love function and Flügge shell theory. Numerical work has been done with a computer for various values of shell geometry parameters and elastic constants.

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Many residential and small business users connect to the Internet via home gateways, such as DSL and cable modems. The characteristics of these devices heavily influence the quality and performance of the Internet service that these users receive. Anecdotal evidence suggests that an extremely diverse set of behaviors exists in the deployed base, forcing application developers to design for the lowest common denominator. This paper experimentally analyzes some characteristics of a substantial number of different home gateways: binding timeouts, queuing delays, throughput, protocol support and others.

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A variety of N-alkyl-beta-aminodiselenides have been synthesized in high yield from sulfamidates under mild reaction conditions using potassium selenocyanate and benzyltriethylammonium tetrathiomolybdate ([BnNEt3](2)MoS4) in a sequential, one-pot, multistep reaction. The tolerance of multifarious protecting groups under the reaction conditions is discussed. The methodology was successfully extended to the synthesis of selenocystine,3,3'-dialkylselenocystine, and 3,3'-diphenylisoselenocystine and their direct incorporation into peptides.

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Wear studies of engine components of high-speed diesel engines running under various operating conditions are presented. Tests were conducted under controlled conditions over long periods. The results of the various tests are discussed and attempts have been made to examine the effects of engine operating variables and the quality of the lubricating oil on the wear of engine components.

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Experiments were conducted in cement cisterns to find out the effect of adding different dosages of activated sludge on fish growth and plankton production. Three dosages of sludge,viz., 62·5 gm., 125 gm. and 250 gm. per 240 litres of water were used. Fingerlings ofCyprinus carpio, Cirrhina mrigala andCatla catla responded positively,C. mrigala showing maximum growth. The results indicate that the sludge has a direct influence on increasing growth of fish and production of plankton due to the release of nutrients into the water. The increase in plankton content stops after about 30 days. When greater quantities of sludge were added in the cisterns, fish mortality took place.

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CeO2-SnO2 solid solution has been reported to possess high oxygen storage/release property which possibly originates from local structural distortion. We have performed first-principles based density functional calculations of Ce1-xSnxO2 structure (x=0, 0.25, 0.5, 1) to understand its structural stability in fluorite in comparison to rutile structure of the other end-member SnO2, and studied the local structural distortion induced by the dopant Sn ion. Analysis of relative energies of fluorite and rutile phases of CeO2, SnO2, and Ce1-xSnxO2 indicates that fluorite structure is the most stable for Ce1-xSnxO2 solid solution. An analysis of local structural distortions reflected in phonon dispersion show that SnO2 in fluorite structure is highly unstable while CeO2 in rutile structure is only weakly unstable. Thus, Sn in Ce1-xSnxO2-fluorite structure is associated with high local structural distortion whereas Ce in Ce1-xSnxO2-rutile structure, if formed, will show only marginal local distortion. Determination of M-O (M=Ce or Sn) bond lengths and analysis of Born effective charges for the optimized structure of Ce1-xSnxO2 show that local coordination of these cations changes from ideal eightfold coordination expected of fluorite lattice to 4+4 coordination, leading to generation of long and short Ce-O and Sn-O bonds in the doped structure. Bond valence analyses for all ions show the presence of oxygen with bond valence similar to 1.84. These weakly bonded oxygen ions are relevant for enhanced oxygen storage/release properties observed in Ce1-xSnxO2 solid solution. (C) 2010 American Institute of Physics.

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Integrating low dielectric permittivity (low-k) polymers to metals is an exacting fundamental challenge because poor bonding between low-polarizability moieties and metals precludes good interfacial adhesion. Conventional adhesion-enhancing methods such as using intermediary layers are unsuitable for engineering polymer/metal interfaces for many applications because of the collateral increase in dielectric permittivity. Here, we demonstrate a completely new approach without surface treatments or intermediary layers to obtain an excellent interfacial fracture toughness of > 13 J/m(2) in a model system comprising copper. and a cross-linked polycarbosilane with k similar to 2.7 obtained by curing a cyclolinear polycarbosilane in air.Our results suggest that interfacial oxygen catalyzed molecularring-opening and anchoring of the opened ring moieties of the polymer to copper is the main toughening mechanism. This novel approach of realizing adherent low-k polymer/metal structures without intermediary layers by activating metal-anchoring polymer moieties at the interface could be adapted for applications such as device wiring and packaging, and laminates and composites.