Assignment of raw material and authentication of spirits by gas chromatography, hydrogen- and carbon-isotope ratio measurements I. Analytical methods and results of a study of commercial products

Gas chromatography and the determination of natural isotope ratios are powerful analytical methods which can be used to check the authenticity of alcoholic beverages and to detect any adulteration. To check the origin and the authenticity of commercial fruit spirits, whiskies, etc., 197 samples were analysed by gas chromatography, ²H-NMR and ¹³C isotope mass spectrometry. The discrimination between different varieties was demonstrated by bivariate and multivariate discriminant analysis using different concentrations of volatile compounds such as methanol, butan-1-ol, 2- and 3-methyl-butanol, benzaldehyde and hexanol as well as isotopic data like (D/H)_I, (D/H)_II and ¹³C/¹²C isotopomers of ethanol. The results show that by using multivariate discriminant analysis it is possible to distinguish not only between different groups of spirits, e.g. those made of stone-fruit, malaceous fruit, grain and corn, but also between individual varieties, such as cherry, plum, mirabelle and apple. If the detection of highly rectified ethyl alcohol of agricultural origin and the identification of its raw materials are required, then natural isotope ratios are the only discriminant analytical parameters available.     

A Comprehensive Analysis of Macrosegregation Formation During Twin-Roll Casting

Metallurgical and Materials Transactions B - A two-phase Eulerian–Eulerian volume-averaged model is used to predict the formation of macrosegregation during the twin-roll casting of...     

Modeling of Conductivity Versus Density Behavior in Green-State Powder Metallurgy Compacts

Ongoing research at Worcester Polytechnic Institute (WPI) has recently resulted in the development of an electrostatic multipin instrument capable of testing green-state compacts directly after compaction. By monitoring a steady electric current flow through the sample and recording the voltages over the surface valuable information is gathered, leading to the prediction of the structural health of the green-state parts. Whereas our prior work concentrated on the detection of surface-breaking and subsurface defects, which requires the determination of large differences in material properties over small flaw sizes, the results presented in this paper aim at the density prediction throughout the volume of the sample. This requires the detection of small changes in material properties over large regions. A physical model and a mathematical formulation are reported, which are capable of relating green-state density changes to electric conductivity in the presence of various lubricant concentrations. Preliminary electrostatic measurements of cylindrical compacts have thus far confirmed the theoretical model assumptions, showing that the electric conductivity follows a complex graphical behavior that is determined by the type and concentration of the lubricant. Specifically, the green state conductivity increases as the sample density increases up to values of approximately 6.9 to 7.0 g/cm³. Any further density increase, however, results in a decrease in conductivity.     

Bilateral peroneal nerve palsy secondary to a knee board: report of two cases

We report on two patients who developed bilateral peroneal nerve palsy after using a knee board behind a water ski boat. This device causes the rider's knees to be in a hyperflexed position secured with a strap across the thighs. Treatment for this compressive neuropathy is conservative. Recreational users may wish to limit the duration and frequency of participation in this sport, thus decreasing the predisposition to prolonged nerve compression. In addition, manufacturers may consider making fundamental design changes such as padding the nylon straps or outrigger devices that contact the proximal lateral tibia.     

A New Prototype Two‐Phase (TiNi)–(β‐W) SMA System with Tailorable Thermal Hysteresis

The Ti–Ni–W two‐phase shape memory alloy (SMA) thin film system is presented as a prototype for new SMAs with tailorable thermal transformation hysteresis (ΔT). The concept is to combine the SMA TiNi with almost insoluble W to create the two‐phase system (TiNi)–(β‐W). This system behaves like a pseudobinary TiNi system. Phase transformation behavior for compositions above the solubility limit of W in TiNi exhibit a B2–R phase transformation with characteristically small ΔT. Moreover, ΔT is dependent on the amount of W and it can be tailored to zero and even negative. This phenomenon is rationalized as being due to the mechanical interaction between the phases B2‐TiNi and β‐W. The presented results are very promising for the development of high‐speed Ti–Ni‐based SMA actuators.     

Glycerol gangliotomy of the second dorsal cervical root in rats: an experimental study to evaluate a minimal invasive approach for the treatment of the chronic cervicogenic headache

The purpose of this integrated literature review (1980-1997) is to describe and summarize specific nursing interventions that have been devised to aid community-dwelling older adults with self-administration of prescribed medications. Interventions that combine patient education with written information or follow-up phone calls produce the most positive results. By using interventions supported by research, nurses will provide more effective and efficient care to older adults managing medications at home.     

Nonstoichiometry and Defect Chemistry of Ceria Solid Solutions

Ceria solid solutions are potential electrolytes for solid oxidefuel cells (SOFC). At the anode side of SOFCs at low oxygen partialpressures ceria is partially reduced. The nonstoichiometry ofCeO_2-x solid solutions with 20 mol%SmO_1.5, 20 mol% GdO_1.5 and 10 mol%CaO were investigated by isothermal coulometric titration in a zirconia cellin the temperature range from 700 to 900°C and in the oxygen partialpressure range from 10^-12 to 10^-25 atm. Theresults of the 3 different compositions at 900°C are comparable to thosefor pure ceria. At lower temperatures, pure ceria is more stable againstreduction than ceria solid solutions. The dependence of nonstoichiometry onoxygen partial pressure suggests a defect model with oxygen vacancies andtheir associates with reduced cerium cations and dopant cations. Low oxygennonstoichiometries of x = 0.005 to 0.008 can be expected for ceria solidsolutions at 700° under SOFC operating conditions.     

Influence of ageing on the dynamic behaviour and the electrochemical characteristics of a 500 We PEMFC stack

In this study, a 500 We 19 cells Proton exchange membrane fuel cell (PEMFC) stack was aged for ∼1200 h and submitted to current steps between different operating levels. Using two different multi-channel data acquisition systems (one at 100 kHz and one at 1 Hz). the evolution with ageing of individual cells and full stack's short term (∼10 s) and medium term (∼4 min) dynamic performances was followed. Undershoots and overshoots behaviours were observed for respective current step-up and step-down. It appeared that, in studied operating conditions, the first time constant was related to the charge transfer at electrode/electrolyte interfaces. After the first “plateau”, the voltage evolution was explained by a membrane water content evolution.     

A three-phase model for mixed columnar-equiaxed solidification

A three-phase model for mixed columnar-equiaxed solidification is presented in this article. The three phases are the parent melt as the primary phase, as well as the solidifying columnar dendrites and globular equiaxed grains as two different secondary phases. With an Eulerian approach, the three phases are considered as spatially coupled and interpenetrating continua. The conservation equations of mass, momentum, species, and enthalpy are solved for all three phases. An additional conservation equation for the number density of the equiaxed grains is defined and solved. Nucleation of the equiaxed grains, diffusion-controlled growth of both columnar and equiaxed phases, interphase exchanges, and interactions such as mass transfer during solidification, drag force, solute partitioning at the liquid/solid interface, and release of latent heat are taken into account. Binary steel ingots (Fe-0.34 wt pct C) with two-dimensional (2-D) axis symmetrical and three-dimensional (3-D) geometries as a benchmark were simulated. It is demonstrated that the model can be used to simulate the mixed columnar-equiaxed solidification, including melt convection and grain sedimentation, macrosegregation, columnar-to-equiaxed-transition (CET), and macrostructure distribution. The model was evaluated by comparing it to classical analytical models based on limited one-dimensional (1-D) cases. Satisfactory results were obtained. It is also shown that in order to apply this model for industrial castings, further improvements are still necessary concerning some details.     

Scaling planar silicon devices

The generation-over-generation scaling of critical CMOS technology parameters is ultimately bound by nonscalable limitations, such as the thermal voltage and the elementary electronic charge. Sustained improvement in performance and density has required the introduction of new device structures and materials. Partially depleted SOI, a most recent MOSFET innovation, has extended VLSI performance while introducing unique idiosyncrasies. Fully depleted SOI is one logical extension of this device design direction. Gate dielectric tunneling, device self-heating, and single-event upsets present developers of these next-generation devices with new challenges. Strained silicon and high-permittivity gate dielectric are examples of new materials that will enable CMOS developers to continue to deliver device performance enhancements in the sub-100 nm regime.