Microstructure and properties of PbCa grade alloys for starting battery grids

The paper presents results of the studies into microstructure and mechanical properties of PbCa grade alloys for starting battery grids. Three lead-calcium alloys with alloy additions of aluminium, tin, silver and magnesium were studied. Lead alloys were produced in laboratory tests from industrial master alloys and pure elements. The examined alloys have monophase microstructure of tin solid solution in the lead. The range between liquidus and solidus temperatures is c.a. 10 °C. The mechanical properties alloys depend on the amount of tin. PbCa alloys exposed to the process of natural ageing increase their strength, proof strength and hardness, simultaneously the plasticity decreases

Osmosensitivity of Transient Receptor Potential Vanilloid 1 Is Synergistically Enhanced by Distinct Activating Stimuli Such as Temperature and Protons

In animals, body-fluid osmolality is continuously monitored to keep it within a narrow range around a set point (∼300 mOsm/kg). Transient receptor potential vanilloid 1 (TRPV1), a cation channel, has been implicated in body-fluid homeostasis in vivo based on studies with the TRPV1-knockout mouse. However, the response of TRPV1 to hypertonic stimuli has not been demonstrated with heterologous expression systems so far, despite intense efforts by several groups. Thus, the molecular entity of the hypertonic sensor in vivo still remains controversial. Here we found that the full-length form of TRPV1 is sensitive to an osmotic increase exclusively at around body temperature using HEK293 cells stably expressing rat TRPV1. At an ambient temperature of 24°C, a slight increase in the intracellular calcium concentration ([Ca2+]i) was rarely observed in response to hypertonic stimuli. However, the magnitude of the osmosensitive response markedly increased with temperature, peaking at around 36°C. Importantly, the response at 36°C showed a robust increase over a hypertonic range, but a small decrease over a hypotonic range. A TRPV1 antagonist, capsazepine, and a nonspecific TRP channel inhibitor, ruthenium red, completely blocked the increase in [Ca2+]i. These results endorse the view that the full-length form of TRPV1 is able to function as a sensor of hypertonic stimuli in vivo. Furthermore, we found that protons and capsaicin likewise synergistically potentiated the response of TRPV1 to hypertonic stimuli. Of note, HgCl2, which blocks aquaporins and inhibits cell-volume changes, significantly reduced the osmosensitive response. Our findings thus indicate that TRPV1 integrates multiple different types of activating stimuli, and that TRPV1 is sensitive to hypertonic stimuli under physiologically relevant conditions

Hydration level is an internal variable for computing motivation to obtain water rewards in monkeys

In the process of motivation to engage in a behavior, valuation of the expected outcome is comprised of not only external variables (i.e., incentives) but also internal variables (i.e., drive). However, the exact neural mechanism that integrates these variables for the computation of motivational value remains unclear. Besides, the signal of physiological needs, which serves as the primary internal variable for this computation, remains to be identified. Concerning fluid rewards, the osmolality level, one of the physiological indices for the level of thirst, may be an internal variable for valuation, since an increase in the osmolality level induces drinking behavior. Here, to examine the relationship between osmolality and the motivational value of a water reward, we repeatedly measured the blood osmolality level, while 2 monkeys continuously performed an instrumental task until they spontaneously stopped. We found that, as the total amount of water earned increased, the osmolality level progressively decreased (i.e., the hydration level increased) in an individual-dependent manner. There was a significant negative correlation between the error rate of the task (the proportion of trials with low motivation) and the osmolality level. We also found that the increase in the error rate with reward accumulation can be well explained by a formula describing the changes in the osmolality level. These results provide a biologically supported computational formula for the motivational value of a water reward that depends on the hydration level, enabling us to identify the neural mechanism that integrates internal and external variables

Intestinal Epithelial Stem/Progenitor Cells Are Controlled by Mucosal Afferent Nerves

Background: The maintenance of the intestinal epithelium is of great importance for the survival of the organism. A possible nervous control of epithelial cell renewal was studied in rats and mice. Methods: Mucosal afferent nerves were stimulated by exposing the intestinal mucosa to capsaicin (1.6 mM), which stimulates intestinal external axons. Epithelial cell renewal was investigated in the jejunum by measuring intestinal thymidine kinase (TK) activity, intestinal H-3-thymidine incorporation into DNA, and the number of crypt cells labeled with BrdU. The influence of the external gut innervation was minimized by severing the periarterial nerves. Principal Findings: Luminal capsaicin increased all the studied variables, an effect nervously mediated to judge from inhibitory effects on TK activity or H-3-thymidine incorporation into DNA by exposing the mucosa to lidocaine (a local anesthetic) or by giving four different neurotransmitter receptor antagonists i.v. (muscarinic, nicotinic, neurokinin1 (NK1) or calcitonin gene related peptide (CGRP) receptors). After degeneration of the intestinal external nerves capsaicin did not increase TK activity, suggesting the involvement of an axon reflex. Intra-arterial infusion of Substance P (SP) or CGRP increased intestinal TK activity, a response abolished by muscarinic receptor blockade. Immunohistochemistry suggested presence of M3 and M5 muscarinic receptors on the intestinal stem/progenitor cells. We propose that the stem/progenitor cells are controlled by cholinergic nerves, which, in turn, are influenced by mucosal afferent neuron(s) releasing acetylcholine and/or SP and/or CGRP. In mice lacking the capsaicin receptor, thymidine incorporation into DNA and number of crypt cells labeled with BrdU was lower than in wild type animals suggesting that nerves are important also in the absence of luminal capsaicin, a conclusion also supported by the observation that atropine lowered thymidine incorporation into DNA by 60% in control rat segments. Conclusion: Enteric nerves are of importance in maintaining the intestinal epithelial barrier.Original Publication:Ove Lundgren, Mats Jodal, Madeleine Jansson, Anders T Ryberg and Lennart Svensson, Intestinal Epithelial Stem/Progenitor Cells Are Controlled by Mucosal Afferent Nerves, 2011, PLOS ONE, (6), 2, 16295.http://dx.doi.org/10.1371/journal.pone.0016295Copyright: Public Library of Science (PLoS)http://www.plos.org

TMEM106B is a genetic modifier of frontotemporal lobar degeneration with C9orf72 hexanucleotide repeat expansions

Hexanucleotide repeat expansions in chromosome 9 open reading frame 72 (C9orf72) have recently been linked to frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis, and may be the most common genetic cause of both neurodegenerative diseases. Genetic variants at TMEM106B influence risk for the most common neuropathological subtype of FTLD, characterized by inclusions of TAR DNA-binding protein of 43 kDa (FTLD-TDP). Previous reports have shown that TMEM106B is a genetic modifier of FTLD-TDP caused by progranulin (GRN) mutations, with the major (risk) allele of rs1990622 associating with earlier age at onset of disease. Here, we report that rs1990622 genotype affects age at death in a single-site discovery cohort of FTLD patients with C9orf72 expansions (n = 14), with the major allele correlated with later age at death (p = 0.024). We replicate this modifier effect in a 30-site international neuropathological cohort of FTLD-TDP patients with C9orf72 expansions (n = 75), again finding that the major allele associates with later age at death (p = 0.016), as well as later age at onset (p = 0.019). In contrast, TMEM106B genotype does not affect age at onset or death in 241 FTLD-TDP cases negative for GRN mutations or C9orf72 expansions. Thus, TMEM106B is a genetic modifier of FTLD with C9orf72 expansions. Intriguingly, the genotype that confers increased risk for developing FTLD-TDP (major, or T, allele of rs1990622) is associated with later age at onset and death in C9orf72 expansion carriers, providing an example of sign epistasis in human neurodegenerative disease

Four-point probe resistivity noise measurements of GaSb layers

This paper concerns measurements and calculations of low frequency noise for semiconductor layers with four-probe electrodes. The measurements setup for the voltage noise cross-correlation method is described. The gain calculations for local resistance noise are performed to evaluate the contribution to total noise from different areas of the layer. It was shown, through numerical calculations and noise measurements, that in four-point probe specimens, with separated current and voltage terminals, the non-resistance noise of the contact and the resistance noise of the layer can be identified. The four-point probe method is used to find the low frequency resistance noise of the GaSb layer with a different doping type. For n-type and p-type GaSb layers with low carrier concentrations, the measured noise is dominated by the non-resistance noise contributions from contacts. Low frequency resistance noise was identified in high-doped GaSb layers (both types). At room temperature, such resistance noise in an n-type GaSb layer is significantly larger than for p-type GaSb with comparable doping concentration

Druty bimetalowe - technologia mechanicznego platerowania na zimno oraz własności użytkowe

Technologies for the production of Fe/Cu and FeNi42/Cu type cladded wires, their physical and mechanical properties and some areas of application, have been presented. The paper outlines the mechanism and conditions of cladding a composite material consisting of two different metals with a circular cross-section, having a form of a tube with a core wire placed inside that tube in the process of mechanical bonding performed with the use of cold drawing and diffusive annealing. Analysis of the cladding process and results of related research and tests carried out have been presented. These technological tests, including bending, torsion test and flattening, and examination of mechanical properties, were aimed at evaluating quality of metallurgical bonding between bimetal components. Particularly important appeared to be microstructure examination carried out with the use of X-ray micro-analyser, which enabled to evaluate degree of atomic diffusion at the boundary between the metals joined. Tests were also made with coating the surface of FeNi42/Cu bimetallic wires with a thin layer of borax, Cu2O copper oxide and nickel in order to check possibility of using them as lead-in wires in different light bulbs or electronic subassemblies. Production technology of bimetallic wires has been developed at the Institute of Non-Ferrous Metals under many research and development projects. Evaluation of their functional properties was made.W pracy przedstawiono technologie otrzymywania drutów bimetalowych typu Fe/Cu oraz FeNi42/Cu, ich własności fizyko-mechaniczne, a także podano niektóre obszary zastosowania. Omówiono mechanizm i warunki platerowania kompozytu dwóch różnych metali o przekroju kołowym-rurka z umieszczonym w niej drutem rdzeniowym w procesie mechanicznego ich łączenia, wykorzystując operacje ciągnienia na zimno i dyfuzyjnego wyzarzania. Przedstawiono analize procesu platerowania w/w metali oraz zaprezentowano wyniki prób badawczo doświadczalnych w tym zakresie. Do oceny stopnia połaczenia metalurgicznego składników bimetalu wykorzystywano zarówno próby technologiczne tj: zginanie, skrecanie, spłaszczanie oraz badania własności wytrzymałosciowych. Ważne w tym zakresie okazały sie badania mikrostruktury-szczególnie z wykorzystaniem mikroanalizy rentgenowskiej do oceny stopnia dyfuzji atomów na granicy strefy połaczenia metali. Przeprowadzono takze badania w zakresie nakładania cienkich warstw boraksu, tlenku miedzi Cu2O oraz niklu na powierzchnie drutu bimetalowego FeNi42/Cu w aspekcie wykorzystywania tych drutów na doprowadzenia pradu w róznego typu zarówkach oraz podzespołach elektronicznych. Dokonano takze oceny własnosci uzytkowych drutów bimetalowych, których technologia wytwarzania opracowana została w Instytucie Metali Niezelaznych w ramach realizacji szeregu prac badawczo–rozwojowych i wdrozeniowych

Mikrostruktura oraz właściwości tribologiczne materiałów kompozytowych na osnowie miedzi z udziałem cząstek faz smarnych

The paper presents results of the studies into influence of individual particles of lubricating phase on microstructure and tribological properties of copper based composite materials for slide bearings. The studied material was composed of copper alloys with lubricating phase particles, e.g. in a form of graphite and glassy carbon. The metallic matrix of composite materials consisted of Cu-Sn type alloys. Production of the examined materials included processes with complete or partial participation of liquid phase and was conducted in two ways. In production of composites both classical powder metallurgy technology was applied and a method of melting with simultaneous mechanical stirring in liquid state (stir casting). Particles of lubricating phases were heated up to the temperature of 200°C and introduced into a liquid metal and then stirring process at constant rate of 1500 rpm rotational speed was applied. To improve wettability of graphite and glassy carbon particles titanium was introduced into the metallic matrix. In production of the composites by powder metallurgy methods the process consisted of mixing of bronze powders and particles of non-metallic phases and then their consolidation. Both quantitative and qualitative structure analysis of the produced composites was performed. Also through evaluation of tribological properties (friction coefficient, wear) with CSM Instruments high temperature tribometer THT was conducted.W pracy zamieszczono wyniki badań dotyczące wpływu poszczególnych cząstek faz smarnych na mikrostrukturę oraz właściwości tribołogiczne materiałów kompozytowych na osnowie miedzi przeznaczonych na łożyska ślizgowe. Przedmiot badań stanowiły stopy miedzi z udziałem cząstek faz smarnych m.in. w postaci: grafitu oraz węgla szklistego. Metaliczną osnowę materiałów kompozytowych stanowiły stopy z układu Cu-Sn Proces wytwarzania badanych materiałów obejmował procesy przebiegające z całkowitym oraz częściowym udziałem fazy ciekłej i przebiegał dwutorowo. Do wytwarzania kompozytów zastosowano zarówno metodę klasycznej metalurgii proszków, jak i metodę topienia z jednoczesnym mieszaniem mechanicznym w stanie ciekłym (stir casting). Do ciekłego metalu wprowadzono podgrzane do temperatury 200°C cząstki faz smarnych, a następnie prowadzono proces mieszania stosując stałą prędkość obrotową na poziomie 1500 obr/min. W celu poprawy zwilżalności cząstek grafitu i węgla szklistego do osnowy metalicznej wprowadzono tytan. W przypadku otrzymywania kompozytów na drodze metalurgii proszków proces obejmował mieszanie proszków brązu oraz cząstek faz niemetalicznych, a następnie ich konsolidację. Wytworzone materiały kompozytowe poddano analizie struk- tury zarówno w ujęciu ilościowym, jak i jakościowym. Dokonano również szczegółowej oceny właściwości tribologicznych (współczynnik tarcia, zużycie) przy wykorzystaniu tribometru wysokotemperaturowego THT firmy CSM Instruments

ΔN-TRPV1: A Molecular Co-detector of Body Temperature and Osmotic Stress

Thirst and antidiuretic hormone secretion occur during hyperthermia or hypertonicity to preserve body hydration. These vital responses are triggered when hypothalamic osmoregulatory neurons become depolarized by ion channels encoded by an unknown product of the transient receptor potential vanilloid-1 gene (Trpv1). Here, we show that rodent osmoregulatory neurons express a transcript of Trpv1 that mediates the selective translation of a TRPV1 variant that lacks a significant portion of the channel’s amino terminus (ΔN-TRPV1). The mRNA transcript encoding this variant (Trpv1dn) is widely expressed in the brains of osmoregulating vertebrates, including the human hypothalamus. Transfection of Trpv1dn into heterologous cells induced the expression of ion channels that could be activated by either hypertonicity or by heating in the physiological range. Moreover, expression of Trpv1dn rescued the osmosensory and thermosensory responses of single hypothalamic neurons obtained from Trpv1 knockout mice. ΔN-TRPV1 is therefore a co-detector of core body temperature and fluid tonicity