1,516 research outputs found
Chrysanthemum species used as food and medicine: Understanding quality differences on the global market
Background
Chrysanthemum flowers [Ch. x morifolium (Ramat.) Hemsl. and Ch. indicum L.] are a globally used and pharmacologically interesting botanical drug, however, with variable product quality.
Objective
We aim at understanding the chemical variability of primary material available commercially based on different origins and associated quality problems like contamination with heavy metals. This needs to be assessed in the context of the current regulations for this botanical drug and associated problems.
Material and Methods
15 C. indicum L. and 50 C. x morifolium (Ramat.) Hemsl., including a range of geographical cultivars recognized in China, samples from the USA, Europe and China were analyzed using High Performance Thin Layer Chromatography (HPTLC) to compare their general chemical profile. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was used to quantify heavy metal contamination.
Results
The: HPTLC fingerprints of C. indicum samples are clearly distinguishable from C. x morifolium. Fingerprints of samples from the same cultivars collected from markets in different countries (USA and China) show different patterns. Large variance of fingerprints within each cultivar group was observed. The heavy metal analysis showed excessive amounts of some harmful heavy metal in some commercial products with excessive cadmium being the most frequent problem.
Conclusions
The Chinese medicinal cultivars vary. Differences between samples sourced from the USA and China might be ascribable to geographical factors (e.g. soil composition), degradation during transport/storage or adulteration, but geographical differences should also be taken into account. Importantly, a much more detailed definition of the drug are needed for better quality control. In addition, with continuous contamination problem observed, a more widespread regulation is an essential requirement for better quality
SPHERICAL VS CYLINDRICAL ENGINE BEARINGS
ABSTRACT Spherical bearings have been used successfully in engines for some years. The spherical bearing geometry allows a simplified axisymmetric piston design; gradual rotation of the piston and rings results in axisymmetric sidewall wear, temperature distribution and thermal expansion. A previouslydescribed concept engine design incorporating a spherical joint piston was based on an existing production engine with a conventional cylindrical piston pin. Previously-developed finite element lubrication analysis methods are applied to both designs and predictive comparisons made. INTRODUCTION Spherical bearings have been used successfully in engines for some years. The large (400 mm bore) Sulzer Z40 series medium speed 4-stroke Diesel engine has a spherical piston bearing which has been well-documented by its maker The spherical bearing design allows a simplified axisymmetric piston design; gradual rotation of the piston and rings results in axisymmetric sidewall wear, temperature distribution and thermal expansion. Development of a low heat rejection Diesel engine sponsored by the Department of Energy (DOE) and monitored by NASA-Lewis began at Cummins Engine Company in 1989 and ended around 1995 [3-8]. The LE-55 (Low Emission, 55% thermal efficiency) concept engine design incorporating a spherical joint piston was based on an existing Cummins L10 production engine with a conventional cylindrical piston pin. The Cummins L10 was a 10 liter 6 cylinder in-line Diesel engine produced for 15 years ending around 1998. The SCE (Single-Cylinder Engine) L10 version used for test purposes formed the basis for successful life tests of LE-55 hardware
Dynamics of offset bearings: parametric studies
Novel "offset" designs offer greatly improved durability in applications fo
Activation energy for fluorine transport in amorphous silicon
The transport of ion implanted F in amorphous Si is studied using secondary ion mass spectroscopy and transmission electron microscopy. Significant redistribution of F is observed at temperatures in the range 600°C to 700°C. The measured F depth-profiles are modelled using a simple Gaussian solution to the diffusion equation, and the diffusion coefficient is deduced at each temperature. An activation energy of 2.2eV±0.4eV for F transport is extracted from an Arrhenius plot of the diffusion coefficients. It is shown that the F transport is influenced by implantation induced defects
Criminal narrative experience: relating emotions to offence narrative roles during crime commission
A neglected area of research within criminality has been that of the experience of the offence for the offender. The present study investigates the emotions and narrative roles that are experienced by an offender while committing a broad range of crimes and proposes a model of Criminal Narrative Experience (CNE). Hypotheses were derived from the Circumplex of Emotions (Russell, 1997), Frye (1957), Narrative Theory (McAdams, 1988) and its link with Investigative Psychology (Canter, 1994). The analysis was based on 120 cases. Convicted for a variety of crimes, incarcerated criminals were interviewed and the data were subjected to Smallest Space Analysis (SSA). Four themes of Criminal Narrative Experience (CNE) were identified: Elated Hero, Calm Professional, Distressed Revenger and Depressed Victim in line with the recent theoretical framework posited for Narrative Offence Roles (Youngs & Canter, 2012). The theoretical implications for understanding crime on the basis of the Criminal Narrative Experience (CNE) as well as practical implications are discussed
Thomas-Fermi approach to resonant tunneling in delta-doped diodes
We study resonant tunneling in B--doped diodes grown by Si-molecular
beam epitaxy. A Thomas-Fermi approach is used to obtain the conduction-band
modulation. Using a scalar Hamiltonian within the effective-mass approximation
we demonstrate that the occurrence of negative differential resistance (NDR)
only involves conduction-band states, whereas interband tunneling effects seem
to be negligible. Our theoretical results are in very good agreement with
recent experimental observations of NDR in this type of diodes.Comment: 6 pages, REVTeX 3.0, 5 figures available from [email protected]
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