A simplified approach to the thermal behaviour of electrolytic Dewar cell calorimeters

A simplified approach, based on the concept of an overall heat loss coefficient, is described for the estimation of time-variant temperature profiles. The computation of the loss coefficient from experimental temperature maxima under programmed power input is also discussed.     

The influence of different centralised pre-packaging systems on the shelf-life of fresh pork

The influence of different centralised pre-packaging systems (PVC, modified atmosphere packaging (MAP), 25% CO(2) and 75% O(2), vacuum skin packaging (VSP) and the mother bag concept, 100% CO(2)) on the shelf-life (0, 7, 14 and 21 days at 0°C) of fresh pork was determined using microbiological, colour, odour and acceptability characteristics. All the packaging treatments were equally efficient for the first 4 days of retail display. In the extended shelf-life study (7, 14 and 21 days) the mother bag centralised packaging system gave the most promising shelf-life results (21 days) and was also judged superior in terms of odour. Modified atmosphere packaging (14 days) and VSP (7 days) may be considered as other possible options.     

Identification and evaluation of volatile compounds of vacuum and modified atmosphere packaged beef strip loins

Beef strip loins were packaged and stored for up to 28 days at 3°C in high-oxygen barrier film under vacuum and in 100% CO(2), 40% CO(2)/60% N(2) and 20% CO(2)/80% O(2). As storage progressed, loins packaged and stored in 20% CO(2)/80% O(2) developed strong off-odors. 1-hexene, methyl thiirane, ethyl acetate, benzene and 1-heptene were detected in these packaged loins beginning at 7 to 14 days of storage. With the exception of 1-hexene, these compounds were not consistently detected in loins stored in vacuum, in 100% CO(2), or in 40% CO(2)/60% N(2), and these packaged loins developed much less off-odor during storage than loins packaged and stored in 20% CO(2)/80% O(2). A large number of volatile compounds from the headspace of the packaged loins originated from the packaging material. Lactobacillus plantarum became the dominant flora on loins stored under vacuum and under 40% CO(2)/60% N(2) while Leuconostoc mesenteroides subsp. mesenteroides predominated in loins stored in 100% CO(2). Pseudomonas putida eventually dominated on loins stored in 20% CO(2)/80% O(2).     

Optical properties of O2 − centres in KCl∶NaCl mixed crystals

The optical properties of O₂ ^– centres in KClNaCl mixed crystals were investigated. The timeresolved spectra and the fluorescence decay time are shown. From the measurements of the radiative decay time, the oscillator strength of the absorption,f _ab=0.045, the oscillator strength of the fluorescence,f _fluo=0.019, and the activation energy E=0.22 eV for the O₂ ^– centre in KClNaCl were determined.     

Synthesis of ceramic membranes

Non-supported -alumina films are prepared from a boehmite colloidal suspension. After calcination at 600°C, the microstructure is characterized by a mean pore diameter of 3 nm, a porosity of 50% and a tortuosity of 5.5. The structure is formed by card packed, plate-shaped particles, giving rise to slit-shaped pores. Supported -alumina films, made by a slipcasting process using the same boehmite precursor, have a similar structure as the non-supported films. The slipcasting process is very sensitive to support characteristics and frequently yields defect films. Polyvinylalcohol (PVA) (molecular weight 72000 g mol^–1) is added to the boehmite precursor (0.25 gg^–1 film) to improve this process. This addition results in a less critical and better controllable drying and calcining procedure. The addition of PVA is necessary to slipcast defect free -alumina films on supports with pore diameters of 0.4 m or smaller and on multi-layer supports. It has no significant effect on the resultant microstructure of the -alumina film, provided all PVA is removed by appropriate thermal treatment. The slipcasting rate is slower, resulting in thinner films of 3–5 m at identical slipcasting times.     

Synthesis of metal nitrides and carbide powders by a spark discharge method in liquid media

Metal nitrides and carbides powders were synthesized by the spark discharge method in liquid ammonia at 100 °C and 11 kV of the spark discharge voltage and in n-heptane at 25 °C and 7.5 kV using the pellets of aluminum, titanium, iron and chromium as the starting material. The main products were AlN, TiN_0.51, -Fe, -Cr₂N in liquid ammonia, and Al₄C₃, TiC, -Fe, Fe₂C and Cr₇C₃ in n-heptane. The agglomerated particle size decreased with increasing melting point of the metal used as the starting material.     

Effects of silicon powder structure of nitriding

A study has been made on how the structural state of the silicon affects the nitriding at 1200–1400C. As the initial powder becomes more defective, the nitriding accelerates, and there is an increase in the importance of reactions in the gas phase, with an increase in the proportion of the a modification of silicon nitride, and a tendency for elongated crystals to form.Translated from Poroshkovaya Metallurgiya, No. 10, pp. 1–7, October, 1992.     

Citations do not solve problems.

D. T. Cambell and D. W. Fiske (1959) made the now-obvious statement that measures of the same variable made by different methods should agree (converge) and certainly should agree better than measures of different variables made by those several methods. Almost everyone accepted that statement, yet the multitrait–multimethod matrices published today show little or no improvement over the published examples cited in 1959. The article raised the conceptual problem of how a variable and its measurement should be linked and the methodological problem of clarifying the nature of methods and their effects. Given these unresolved problems, it is perhaps not surprising that the question of the appropriate statistical analysis of these matrices has also no consensual answer. Perhaps methods and traits or contents are so thoroughly intertwined that their interaction cannot be adequately analyzed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Precision determination of252Cf half-life and the time dependence of the neutron flux of a Ra - Be(α, n) source

Scientific-Industrial Association D. I. Mendeleev All-Union Scientific-Research Institute of Metrology. Translated from Atomnaya Énergiya, Vol. 73, No. 6, pp. 502-504, December, 1992.