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Temperature Cycling (temperature + cycling)
Selected AbstractsTemporal and spatial variations in periglacial soil movements on alpine crest slopesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2005Norikazu Matsuoka Abstract This paper describes up to ten years of continuous monitoring of frost heave, creep and associated parameters on high mountain crest slopes in the Japanese and Swiss Alps, aiming to evaluate spatial and interannual variations in the rates and controls of soil movement. Shallow frost creep re,ecting diurnal frost heave activity dominates the crest slopes that lack a vegetation mat and have a thin debris mantle with good drainage. Seasonal frost heave activity can induce slightly deeper movement where ,ne soil exists below the depth reached by diurnal freeze,thaw penetration, although the shallow bedrock impedes movements below 20 cm depth. As a result, downslope velocity pro,les display strong concavity with surface velocities of 2,50 cm a,1. The frost creep rates vary spatially, depending on the soil texture, slope gradient, frequency of temperature cycling across 0 °C and moisture availability during freeze,thaw periods. Soil movements recur in every freeze,thaw period, although with some interannual variations affected by the length of seasonal snow cover and the occurrence of precipitation during freeze,thaw periods. The Swiss Alps encounter more signi,cant interannual variations than the Japanese Alps, re,ecting the large variability of the annual snow regime. Copyright © 2005 John Wiley & Sons, Ltd. [source] Probing the droplet cluster structure in acidified temperature-cycled o/w emulsion gels by means of SESANS,INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2007Arjen Bot Summary The structure of the emulsion droplet aggregates in whey-protein-stabilised oil-in-water (o/w) model emulsion gels was investigated using the novel spin-echo small-angle neutron scattering (SESANS) technique. This technique allows the assessment of the droplet cluster structure in an emulsion gel in terms of a density correlation function at relatively long length scales (,100 nm,10 µm) compared with regular SANS. As an example, the effect of one/two homogenisation stages on emulsion droplet cluster structure was studied in relation to acidification and temperature cycling. It is found that temperature cycling and acidification induce bigger changes in emulsion droplet cluster structure than the application of one or two homogenisation stages, and the results are compared with droplet size measurements (by pfg-NMR), firmness measurements and confocal microscopic images. [source] Evaluation of hydrate-screening methodsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2008Yong Cui Abstract The purpose of this work is to evaluate the effectiveness and reliability of several common hydrate-screening techniques, and to provide guidelines for designing hydrate-screening programs for new drug candidates. Ten hydrate-forming compounds were selected as model compounds and six hydrate-screening approaches were applied to these compounds in an effort to generate their hydrate forms. The results prove that no screening approach is universally effective in finding hydrates for small organic compounds. Rather, a combination of different methods should be used to improve screening reliability. Among the approaches tested, the dynamic water vapor sorption/desorption isotherm (DVI) method and storage under high humidity (HH) yielded 60,70% success ratios, the lowest among all techniques studied. The risk of false negatives arises in particular for nonhygroscopic compounds. On the other hand, both slurry in water (Slurry) and temperature cycling of aqueous suspension (TCS) showed high success rates (90%) with some exceptions. The mixed solvent systems (MSS) procedure also achieved high success rates (90%), and was found to be more suitable for water-insoluble compounds. For water-soluble compounds, MSS may not be the best approach because recrystallization is difficult in solutions with high water activity. Finally, vapor diffusion (VD) yielded a reasonably high success ratio in finding hydrates (80%). However, this method suffers from experimental difficulty and unreliable results for either highly water-soluble or water-insoluble compounds. This study indicates that a reliable hydrate-screening strategy should take into consideration the solubility and hygroscopicity of the compounds studied. A combination of the Slurry or TCS method with the MSS procedure could provide a screening strategy with reasonable reliability. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:2730,2744, 2008 [source] Piecewise analysis and modeling of circuit pack temperature cycling dataBELL LABS TECHNICAL JOURNAL, Issue 3 2006Toby Joyce Temperature cycling environmental stress testing (EST) of circuit packs is a standard test procedure for the precipitation of latent defects in order to minimize early product lifecycle customer returns. EST is an expensive, energy-intensive bottleneck in the manufacturing process, one that is based on empiricisms that may be out of date. This presents great opportunity for optimization and test cost reduction. This paper describes the characterization of temperature cycling through analysis and modeling of process data in order to optimize the test parameters,ramp rate, temperature extremes, dwell times, and number of cycles. Failure data from circuit packs tested at a Lucent facility is analyzed using a regression technique and graphical inspection. The dwell and ramp periods of the test are considered in a piecewise manner. A cost model is applied based on distributions fitted to the failure data. The analysis yields a methodology for the dynamic, value-based optimization of temperature cycling EST. © 2006 Lucent Technologies Inc. [source] | ||||||||||