Modeling of the Sub-Tg Relaxation Spectrum of Pd42.5Ni7.5Cu30P20 Metallic Glass

In this work we study the mechanical relaxation spectrum of Pd42.5Ni7.5Cu30P20 metallic glass. The effect of aging on the relaxation behavior is analyzed by measuring the internal friction during consecutive heating runs. The mechanical relaxation of the wellannealed glass state is modeled by fitting susceptibility functions to the primary and secondary relaxations of the system. The model is able to reproduce the mechanical relaxation spectrum below the glass transition temperature (sub-Tg) in the frequency- temperature ranges relevant for the high temperature physical properties and forming ability of metallic glasses. The model reveals a relaxation spectrum composed by the overlapping of primary and secondary processes covering a wide domain of times but with a relatively narrow range of activation energies.Postprint (author's final draft

The Impact of Gastrocnemius Muscle Cell Changes in Chronic Venous Insufficiency

AbstractObjectiveTo investigate the pathological and metabolic changes in the gastrocnemius muscle in patients with chronic vein insufficiency (CVI).MethodThirty-six patients with varicose veins were investigated by ambulatory venous pressure (AVP) and duplex ultrasonography. Twelve age and height-matched controls were used for comparison. Patients and controls consented to participate in this study. Twenty-one patients with primary vein varicose (group AI) and 15 patients (group AII) with primary deep venous valve incompetence (DVI) underwent biopsies of the gastrocnemius muscle during operation. Adductor biopsies obtained from the same limbs served as a control group (group B) and specimens from controls subjects without venous disease served as the second control group (group C). All the specimens were investigated by superoxide dismutase (SOD), nitric oxide (NO), Na+–K+-ATPase, Ca2+-ATPase and lactic acid (LD) determinations. Samples were subjected to light and electron microscopy following H & E staining, special ATPase, cytochrome oxidase/succinate dehydrogenase (COX/SDH) stains.ResultsNormal muscle architecture was seen following H & E, ATPase and COX/SDH staining and normal cell metabolism was observed in specimens of groups B and C. In group A, pathological changes were encountered in the gastrocnemius muscle including disseminated myofibril atrophy, cell denaturation and necrosis, inflammatory cell infiltration, proliferation and dilation of interfascicular veins. ATPase staining (pH 9.4) demonstrated grouping of atrophic fibres, especially type I myofibril grouping, accompanied by moderate to severe atrophy of type II muscle fibres. However, no patient had selective type I fibre atrophy. Enhanced enzymatic activity in single or multiple myofibrils was demonstrated by COX/SDH staining in approximately half of the specimens in group AII. In group AII, electron microscopy showed swelling, myelin figure denaturation of mitochondria, disruption of the myofibrils and increased lipid droplets in the gastrocnemius muscle. Increased concentration of LD was found in most specimens from group A patients. There were also reductions of SOD, NO, biochemical activity of Na+–K+-ATPase, Ca2+-ATPase with increasing concentration of LD in these patients, most prominently in group AII. We found correlation between AVP assessments and the biochemical measurements as well as morphological appearances of the gastrocnemius muscle.ConclusionVenous hypertension results in pathophysiological changes in the gastrocnemius muscles of patients with DVI, associated with decreased calf pump function

Quantum switch for single-photon transport in a coupled superconducting transmission line resonator array

We propose and study an approach to realize quantum switch for single-photon transport in a coupled superconducting transmission line resonator (TLR) array with one controllable hopping interaction. We find that the single-photon with arbitrary wavevector can transport in a controllable way in this system. We also study how to realize controllable hopping interaction between two TLRs via a superconducting quantum interference device (SQUID). When the frequency of the SQUID is largely detuned from those of the two TLRs, the variables of the SQUID can be adiabatically eliminated and thus a controllable interaction between two TLRs can be obtained.Comment: 4 pages,3 figure

Endogenous BDNF augments NMDA receptor phosphorylation in the spinal cord via PLCγ, PKC, and PI3K/Akt pathways during colitis

Background Spinal central sensitization is an important process in the generation and maintenance of visceral hypersensitivity. The release of brain-derived neurotrophic factor (BDNF) from the primary afferent neurons to the spinal cord contributes to spinal neuronal plasticity and increases neuronal activity and synaptic efficacy. The N-Methyl-D-aspartic acid (NMDA) receptor possesses ion channel properties, and its activity is modulated by phosphorylation of its subunits including the NMDA receptor 1 (NR1). Methods Colonic inflammation was induced by a single dose of intracolonic instillation of tri-nitrobenzene sulfonic acid (TNBS). NR1 phosphorylation by BDNF in vivo and in culture was examined by western blot and immunohistochemistry. Signal transduction was studied by direct examination and use of specific inhibitors. Results During colitis, the level of NR1 phospho-Ser896 was increased in the dorsal horn region of the L1 and S1 spinal cord; this increase was attenuated by injection of BDNF neutralizing antibody to colitic animals (36 μg/kg, intravenous (i.v.)) and was also reduced in BDNF+/− rat treated with TNBS. Signal transduction examination showed that the extracellular signal-regulated kinase (ERK) activation was not involved in BDNF-induced NR1 phosphorylation. In contrast, the phosphatidylinositol 3-kinase (PI3K)/Akt pathway mediated BDNF-induced NR1 phosphorylation in vivo and in culture; this is an additional pathway to the phospholipase C-gamma (PLCγ) and the protein kinase C (PKC) that was widely considered to phosphorylate NR1 at Ser896. In spinal cord culture, the inhibitors to PLC (U73122), PKC (bisindolylmaleimide I), and PI3K (LY294002), but not MEK (PD98059) blocked BDNF-induced NR1 phosphorylation. In animals with colitis, treatment with LY294002 (50 μg/kg, i.v.) blocked the Akt activity as well as NR1 phosphorylation at Ser896 in the spinal cord. Conclusion BDNF participates in colitis-induced spinal central sensitization by up-regulating NR1 phosphorylation at Ser896. The PI3K/Akt pathway, in addition to PLCγ and PKC, mediates BDNF action in the spinal cord during colitis

Constitutive model of 7075 aluminum at high temperature

In order to obtain the accurate mechanical properties of 7075 aluminum alloy, the Gleeble-1500D thermal simulation test machine was used to perform compression test on 7075 aluminum alloy. The deformation temperature range is 490 °C~560 °C, and the strain rate is 0,001 s-1~1 s-1. At present, for the high temperature thermal compression process, the Arrhenius constitutive model with strain compensation is usually used. The results show that the correlation coefficient of the Arrhenius constitutive model of 7075 aluminum alloy with strain compensation is 0,9894, and the average relative error is 5,6 %, realizing the fitting of flow stress and prediction, verified the feasibility of the model

Constitutive model of 7075 aluminum at high temperature

In order to obtain the accurate mechanical properties of 7075 aluminum alloy, the Gleeble-1500D thermal simulation test machine was used to perform compression test on 7075 aluminum alloy. The deformation temperature range is 490 °C~560 °C, and the strain rate is 0,001 s-1~1 s-1. At present, for the high temperature thermal compression process, the Arrhenius constitutive model with strain compensation is usually used. The results show that the correlation coefficient of the Arrhenius constitutive model of 7075 aluminum alloy with strain compensation is 0,9894, and the average relative error is 5,6 %, realizing the fitting of flow stress and prediction, verified the feasibility of the model