Generation of internal stress and its effects

Internal stresses may be generated continually in many polycrystalline materials. Their existence is manifested by changes in crystal defect concentration and arrangement, by surface observations, by macroscopic shape changes and particularly by alteration of mechanical properties when external stresses are simultaneously imposed

Stabilization of urinary biogenic amines measured in clinical chemistry laboratories.

Urinary 5-hydroxyindoleacetic acid (5-HIAA), vanillylmandelic (VMA), homovanillic acid (HVA), catecholamines and metanephrines are produced in excess by catecholamine-producing tumors. These biogenic amines are unstable at low or high pH and require hydrochloric acid (HCl) to prevent their degradation. However, HCl addition may result in very low pH causing degradation or deconjugation of several metabolites. This study evaluated the buffering properties of sodium citrate to stabilize all biogenic amines. The metabolite concentrations were measured by LC-MS/MS or by a coulometric assay in 22 urine samples collected native and with HCl or sodium citrate. We studied the effect of pH, time (48 h, four weeks) and storage temperature at 22 °C, 4 °C, and -20 °C. We found that catecholamines degradation was prevented by HCl and citrate and that 5-HIAA was degraded in 5 out of 22 samples collected with HCl. All biogenic amines were efficiently stabilized by citrate for four weeks at 22 °C, except epinephrine (48 h at 4 °C, or four weeks at -20 °C). Sodium citrate did not cause quantification or analytical artefacts concerns. In conclusion, sodium citrate is a non-hazardous alternative to HCl for patients to send unfrozen urine samples to the laboratory which may safely store the sample for four weeks

Porous Titanium Cylinders Obtained by the Freeze-Casting Technique: Influence of Process Parameters on Porosity and Mechanical Behavior

 The discrepancy between the stiffness of commercially pure titanium and cortical bone  tissue compromises its success as a biomaterial. The use of porous titanium has been widely studied,  however, it is still challenging to obtain materials able to replicate the porous structure of the bones  (content, size, morphology and distribution). In this work, the freeze‐casting technique is used to  manufacture cylinders with elongated porosity, using a home‐made and economical device. The  relationship between the processing parameters (diameter and material of the mold, temperature  gradient), microstructural features and mechanical properties is established and discussed, in terms  of ensuring biomechanical and biofunctional balance. The cylinders have a gradient porosity  suitable for use in dentistry, presenting higher Young’s modulus at the bottom, near the cold spot  and, therefore better mechanical resistance (it would be in contact with a prosthetic crown), while  the opposite side, the hot spot, has bigger, elongated pores and walls.  Ministry of Economy and Competitiveness of Spain  grant  MAT2015‐71284‐P  FEDER‐Junta de Andalucía Research  Project (Modeling and implementation of the freeze casting technique: gradients of porosity with a tribomechanical equilibrium and electro‐stimulated cellular behavior).

SMARTS— a spectrometer for strain measurement in engineering materials

Abstract. A new spectrometer called SMARTS (Spectrometer for Materials Research at Temperature and Stress) has been commissioned at the Los Alamos neutron science center and entered the user program in August of 2002. Its design maximizes capability and throughput for measurements of (a) residual macrostrain in engineering components and (b) in situ loading. This paper describes some aspects of the instrument. 61.12Ex; 62.20Fe; 62.20Hg Measurements of strain in engineering materials place demands on neutron diffraction spectrometers that differ from instruments designed for conventional crystallography. Notably the range in shape and size of engineering specimens requires more spacious access to the sample position than is typically found on conventional diffractometers. Moreover efficient and accurate measurements require precise optical alignment (of samples with irregular shapes) with respect to the beam -which imposes limitations on shielding and lineof-sight access to the sample. Over the last few years these limitations have led to adaptation of existing instruments and new instruments being designed for engineering strain measurements PACS

Stress-induced martensitic transformations in NiTi and NiTi-TiC composites investigated by neutron diffraction

Superelastic NiTi (51.0 at% Ni) with 0, 10 and 20 vol% TiC particles were deformed under uniaxial compression as neutron diffraction spectra were simultaneously obtained. The experiments yielded in-situ measurements of the thermoelastic stress-induced transformation. A detailed Rietveld determination is made of the phase fractions and the evolving strains in the reinforcing TiC particles and the austenite as it transforms to martensite on loading (and its subsequent back transformation on unloading). These strains are used to shed light on the phenomenon of load transfer in composites where the matrix undergoes a stress-induced phase transformation

Quantification of serotonin and eight of its metabolites in plasma of healthy volunteers by mass spectrometry.

Serotonin is transformed into melatonin under the control of the light/dark cycle, representing a cornerstone of circadian rhythmicity. Serotonin also undergoes extensive metabolism to produce 5-hydroxyindoleacetic acid (5-HIAA), a biomarker for the diagnosis and monitoring of serotonin secreting neuroendocrine tumors (NETs). While serotonin, melatonin and their metabolites are part of an integrated comprehensive system, human observations about their respective plasma concentrations are still limited. We report here for the first time a multiplex UHPLC-MS/MS assay for the quantification of serotonin, 5-HIAA, 5-hydroxytryptophol (5-HTPL), N-acetyl-serotonin (NAS), Mel, 6-OH-Mel, 5-methoxytryptamine (5-MT), 5-methoxytryptophol (5-MTPL), and 5-methoxyindoleacetic acid (5-MIAA) in human plasma. Analytes were extracted by protein precipitation and solid phase extraction. Plasma concentrations for these analytes were determined in 102 healthy volunteers. The LLOQ of the assay ranges from 2.2 nM for serotonin to 1.0 pM for 6-OH-Mel. This sensitivity enables the quantification of circulating serotonin, 5-HIAA, NAS, Mel, and 5-MIAA, even at their lowest diurnal concentrations. This assay will enable specific, precise and accurate measurement of serotonin, Mel and their metabolites to draw a detailed picture of this complex pineal metabolism, allowing a dynamic understanding of these pathways and providing promising biomarkers and a metabolic signature for serotonin-secreting NETs

Cypress: A High Yielding, High Quality Long-Grain Rice Variety

Cypress is a high-yielding, early-maturing, semidwarf, long-grain rice variety with excellent grain quality. This bulletin includes information on the history, characteristics, cultural management and pest reaction of Cypress.https://digitalcommons.lsu.edu/agcenter_bulletins/1011/thumbnail.jp

A simple and economical device to process Ti cylinders with elongated porosity by freeze-casting techniques: design and manufacturing [Póster]

Design, manufacture and validation of a simple and economic device that allows producing Ti cylinders with directed porosity applying the freeze-casting technique, and the study of the influence on the internal structure of the Ti porous samples when different materials are used for the vessel (alumina or Teflon).Junta de Andalucía (Spain) Grant No. P12-TEP-1401Ministry of Economy and Innovation of Spain project MAT2015-71284-

Thin-film silicon detectors for particle detection

Integrated particle sensors have been developed using thin-film on ASIC technology. For this purpose, hydrogenated amorphous silicon diodes, in various configurations, have been optimized for particle detection. These devices were first deposited on glass substrates to optimize the material properties and the dark current of very thick diodes (with thickness up to 50 μm). Corresponding diodes were later directly deposited on CMOS readout chips. These integrated particle sensors have been characterized using light pulse illumination and beta particle irradiation from 63Ni and 90Sr sources. Direct detection of single low- and high-energy beta particles have been demonstrated. The application of this new integrated particle sensor concept for medical imaging is also discussed