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Standard Materials (standard + material)
Selected AbstractsEssential oil compounds in a historical sample of marjoram (Origanum majorana L., Lamiaceae)FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2002Johannes Novak Abstract A historical sample of marjoram (Origanum majorana L., Lamiaceae), more than 60 years old, was analysed and its composition compared to standard material from the European herb market. By using a solvent extract of the historical sample, the rearrangements and artefact formation usually occurring during the distillation of marjoram were avoided. The extract contained high amounts of terpinen-4-ol, thus resembling the distilled essential oil more than the solvent extract of the standard sample. So artefact formation in marjoram can also happen in planta in herbs stored for a long time under suboptimal conditions. The high content of carvacrol, normally never present in standard material from cultivation, gave an indication of the heterogeneity of marjoram in former times, and confirmed the opinion that (cultivated) marjoram is a chemovariety selected a long time ago. Copyright © 2002 John Wiley & Sons, Ltd. [source] Copper and calcium uptake in colored hairINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2010K. E. Smart J. Cosmet. Sci., 60, 337,345 (May/June 2009) Accepted for publication December 29, 2008. Synopsis During hair coloring a number of disulfide bonds in cystine are oxidized (1) to create cysteic acid, forming binding sites for metal ions such as Ca2+ and Cu2+ from tap water (2). The increased uptake of these metals can have a detrimental impact on fiber properties,for example, reducing shine and causing a poor wet and dry feel (3). In addition, the increased uptake of copper can also contribute to further fiber damage during subsequent coloring due to its ability to take part in metal-induced radical chemistry (4). It is important to know where in the fibers these metals are located in order to either effectively remove these metals or control their chemistry. Nanoscale secondary ion mass spectrometry (NanoSIMS) has been used to locate the calcium and copper within hair that has been treated with a colorant and washed multiple times in tap water containing these ions. Untreated hair is used as a baseline standard material. Images with up to 50-nm spatial resolution of the preferential locations of calcium uptake were obtained, showing a high concentration of calcium in the cuticle region of colored hair, specifically in the sulfur-rich regions (A-layer and exocuticle). [source] Hydride-based silica stationary phases for HPLC: Fundamental properties and applicationsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 15 2005Joseph J. Pesek Abstract Silica hydride is a recent development in chromatographic support materials for HPLC where hydride groups replace 95% of the silanols on the surface. This conversion changes many of the fundamental properties of the material as well as the bonded stationary phases that are the result of further chemical modification of the hydride surface. The general approach for fabricating the silica hydride and subsequent bonded phases is reviewed. Properties of the silica hydride surface are compared to those of the standard material obtained in the preparation of most commercial HPLC stationary phases. Some unique chromatographic properties of hydride-based phases are described as well as some general application areas where these bonded materials may be used in preference to or have advantages not available from typical stationary phases. [source] An augmented Lagrange multiplier approach to continuum multislip single crystal thermo,elasto,viscoplasticityINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 7 2005C. C. Celigoj Abstract The material and structural behaviour of single crystals is going to be investigated. On the constitutive level the concept of ,generalized standard materials (gsm)' is used to set up the equations for finite deformation multislip single crystal thermo,elasto,viscoplasticity within a continuum slip theory. The only two scalar quantities needed are a thermodynamic potential and a dissipation potential. The resulting evolution equations for the internal (viscoplastic) variables are discretized in time and solved via a backward Euler scheme, using an ,augmented Lagrange multiplier method' for satisfying the multiple constraints, thus circumventing the cumbersome and less robust ,active set strategies'. As a computational reference frame serves the Eulerian setting. The structural behaviour (non-linear coupled thermomechanics) is solved in a staggered algorithm: in an isothermal mechanical phase via q1(displacements)/p0(pressure)/j0(jacobian)-finite elements and in an isogeometric thermal phase via q1(temperatures)-finite elements, followed by an isogeometric and isothermal update phase of the internal variables. Numerical results of the simple isothermal shear test of a single face-centred cubic (fcc) crystal and of the thermomechanical behaviour of a geometrically imperfect strip consisting of initially equally oriented (0/45/30 in Euler angles) fcc-crystals under tension and plane strain conditions are given. Copyright © 2005 John Wiley & Sons, Ltd. [source] Analytical inversion of the Jacobian for a class of generalized standard materialsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Felix Fritzen In this paper we derive an analytical expression for the inverse of the Jacobian occuring in the implicit time integration procedure for a large class of generalized standard materials. The resulting expression is easy to construct and implement into arbitrary programming languages. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Indentation as a technique to assess the mechanical properties of fallback foodsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Peter W. Lucas Abstract A number of living primates feed part-year on seemingly hard food objects as a fallback. We ask here how hardness can be quantified and how this can help understand primate feeding ecology. We report a simple indentation methodology for quantifying hardness, elastic modulus, and toughness in the sense that materials scientists would define them. Suggested categories of fallback foods,nuts, seeds, and root vegetables,were tested, with accuracy checked on standard materials with known properties by the same means. Results were generally consistent, but the moduli of root vegetables were overestimated here. All these properties are important components of what fieldworkers mean by hardness and help understand how food properties influence primate behavior. Hardness sensu stricto determines whether foods leave permanent marks on tooth tissues when they are bitten on. The force at which a food plastically deforms can be estimated from hardness and modulus. When fallback foods are bilayered, consisting of a nutritious core protected by a hard outer coat, it is possible to predict their failure force from the toughness and modulus of the outer coat, and the modulus of the enclosed core. These forces can be high and bite forces may be maximized in fallback food consumption. Expanding the context, the same equation for the failure force for a bilayered solid can be applied to teeth. This analysis predicts that blunt cusps and thick enamel will indeed help to sustain the integrity of teeth against contacts with these foods up to high loads. Am J Phys Anthropol 140:643,652, 2009. © 2009 Wiley-Liss, Inc. [source] Construction and Performance of a Minibioreactor Suitable as Experimental Bioartificial LiverARTIFICIAL ORGANS, Issue 4 2008Joaquín V. Rodriguez Abstract:, This work deals with the construction and performance of a hollow fiber-based minibioreactor (MBR). Due to its simple design and the utilization of standard materials, it could serve as a suitable tool to evaluate the behavior and performance of cold preserved or cultured hepatocytes in bioartificial liver devices. The system consists of 140 fiber capillaries through which goat blood is pumped at a flow of 9 mL/min. The cell compartment contains 90 × 106 rat hepatocytes (volume 10 mL) and an internal oxygenator made of silicone tubing. To test the in vitro function of the system, 2-h perfusion experiments were performed, the evolution of hematocrit, plasma and extra-fiber fluid osmolality, and plasma urea and creatinine concentrations were evaluated. The detoxication efficiency of an ammonia overload was tested, showing that the system has enough capacity to remove ammonium. Also, the MBR oxygen transfer capacity to hepatocytes was tested, showing that the cells received an adequate oxygen supply. [source] | ||||||||||||||||