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Recovery Tests (recovery + test)

Distribution by Scientific Domains

Chemistry	44%
Polymers and Materials Science	22%

Selected Abstracts

RHEOLOGICAL PROPERTIES OF MOZZARELLA CHEESE DETERMINED BY CREEP/RECOVERY TESTS: EFFECT OF SAMPLING DIRECTION, TEST TEMPERATURE AND RIPENING TIME

JOURNAL OF TEXTURE STUDIES, Issue 3 2009
MARÍA LAURA OLIVARES
ABSTRACT The viscoelastic properties of mozzarella cheese using a creep/recovery test considering different sampling directions (parallel and perpendicular to protein fiber orientation), test temperatures (20, 30 and 40C) and ripening times (1, 8, 15, 29 and 36 days) were studied. Creep data were interpreted by a Burger model of four parameters. A semiempirical approach was proposed to obtain the contribution of each main compliance to the total deformation of the system. Creep tests at different temperatures allowed gaining a better understanding of changes that occur in the cheese matrix during heating and ripening. Sampling direction did not affect any of the parameters studied. Finally, it was clearly observed that cheese matrix behaves as a quite different physicochemical system depending on temperature. Therefore, it is recommended to carry out the rheological tests at different temperatures to evaluate appropriately the viscoelastic properties of mozzarella cheese. PRACTICAL APPLICATIONS Mozzarella cheese must have certain characteristics to be used on pizzas and on other prepared foods that use the cheese in melted state. The protein chains in the mozzarella curds coalesce into large strands that are oriented in the direction of stretching. For this reason, mozzarella cheese has an anisotropic structure. Therefore, it is relevant to determine the effect of protein fiber orientation on the rheological properties. Valuable information may be obtained through the creep/recovery test of mozzarella cheese samples to study its rheological properties and to explain molecular mechanisms that occur during ripening or melting processes considering sampling direction. [source]

Methods to Determine Storativity of Infinite Confined Aquifers from a Recovery Test

GROUND WATER, Issue 4 2002
Djaouida Chenaf
Starting from the equations of Theis and Cooper-Jacob, two new mathematical methods are proposed for interpreting the residual drawdown data for an infinite confined aquifer. Under Theis' assumptions and using the Cooper-Jacob approximation, the principal aquifer characteristics of transmissivity, pumping storativity, and recovery storativity are expressed without any correction or additional assumption. An actual case is used for illustration and confirms the validity of proposed equations and methods. [source]

Helophyte germination in a Mediterranean salt marsh: Gut-passage by ducks changes seed response to salinity

JOURNAL OF VEGETATION SCIENCE, Issue 3 2004
J.L. Espinar
Abstract: Question: In seeds which are regularly consumed by waterbirds in the field, how does gut-passage modify their response to salinity gradients? Location: Doñana National Park salt marsh, south-west of Spain. Methods: Seeds of Scirpus litoralis and Scirpus maritimus were collected and force fed to mallards (Anas platyrhynchos). Both the ingested seeds (passage) and non-ingested seeds (controls) were exposed, in germination chambers, to a salinity range similar to that observed in the field (0,32 dS/m). After 30 days, the total percentage germination, the duration of the dormancy period and the germination speed were computed. The response of the different germination parameters to ingestion and salinity was analyzed using generalized lineal models. Recovery tests on seeds that did not germinate in the various treatments and tests of the effect of ingestion on the intrinsic variability in seed response were also performed. Results: An increase in salinity reduced germinability and increased the length of dormancy, while gut pas sage increased the intrinsic variability of the temporal seed response in both species. In S. litoralis there was a significant interaction between the effects of salinity and passage on germination rate. Passage increased germination rate at low salinities (,2 dS/m) but decreased it at high salinities (,4 dS/m). Conclusion: Gut-passage by ducks significantly changes seed response to salinity. The outcome of plant-animal interactions can be influenced by environmental gradients. Studies of germination in response to gut passage that do not take such gradients into account may produce misleading results. [source]

RHEOLOGICAL PROPERTIES OF MOZZARELLA CHEESE DETERMINED BY CREEP/RECOVERY TESTS: EFFECT OF SAMPLING DIRECTION, TEST TEMPERATURE AND RIPENING TIME

Determination of tsumacide residues in vegetable samples using a flow-injection chemiluminescence method

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4 2007
Haiyan Liu
Abstract A sensitive, simple and rapid flow-injection chemiluminescence (FI,CL) method is described to determine tsumacide pesticide residue based on the CL reaction of the alkaline degradation product of tsumacide with acidic KMnO4 when rhodamine 6G was present. Under the optimum conditions, the relative CL intensity is linear with the concentration of tsumacide in the range of 2.0 × 10,3,0.20 mg/L. The detection limit is 6.6 × 10,4 mg/L (3,) and the relative standard deviation for 2.0 × 10,2 mg/L tsumacide solution was 2.28% (intra-day) and 4.85% (inter-day). The proposed method has been applied to determine the residue of tsumacide in vegetable samples and the recovery test is very satisfactory. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Simple method for determination of cocaine and main metabolites in urine by CE coupled to MS

ELECTROPHORESIS, Issue 12 2009
José Luiz da Costa
Abstract In this work, a simple method for the simultaneous determination of cocaine (COC) and five COC metabolites (benzoylecgonine, cocaethylene (CET), anhydroecgonine, anhydroecgonine methyl ester and ecgonine methyl ester) in human urine using CE coupled to MS via electrospray ionization (CE-ESI-MS) was developed and validated. Formic acid at 1,mol/L concentration was used as electrolyte whereas formic acid at 0.05,mol/L concentration in 1:1 methanol:water composed the coaxial sheath liquid at the ESI nozzle. The developed method presented good linearity in the dynamic range from 250,ng/mL to 5000,ng/mL (coefficient of determination greater than 0.98 for all compounds). LODs (signal-to-noise ratio of 3) were 100,ng/mL for COC and CET and 250,ng/mL for the other studied metabolites whereas LOQ's (signal-to-noise ratio of 10) were 250,ng/mL for COC and CET and 500,ng/mL for all other compounds. Intra-day precision and recovery tests estimated at three different concentration levels (500, 1500 and 5000,ng/mL) provided RSD lower than 10% (except anhydroecgonine, 18% RSD) and recoveries from 83,109% for all analytes. The method was successfully applied to real cases. For the positive urine samples, the presence of COC and its metabolites was further confirmed by MS/MS experiments. [source]

Some aspects of the mechanical response of BMI 5250-4 neat resin at 191°C: Experiment and modeling,

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008
M. B. Ruggles-Wrenn
Abstract The inelastic deformation behavior of BMI-5250-4 neat resin, a high-temperature polymer, was investigated at 191°C. The effects of loading rate on monotonic stress,strain behavior as well as the effect of prior stress rate on creep behavior were explored. Positive nonlinear rate sensitivity was observed in monotonic loading. Creep response was found to be significantly influenced by prior stress rate. Effect of loading history on creep was studied in stepwise creep tests, where specimens were subjected to a constant stress rate loading followed by unloading to zero stress with intermittent creep periods during both loading and unloading. The strain-time behavior was strongly influenced by prior deformation history. Negative creep was observed on the unloading path. In addition, the behavior of the material was characterized in terms of a nonlinear viscoelastic model by means of creep and recovery tests at 191°C. The model was employed to predict the response of the material under monotonic loading/unloading and multi-step load histories. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Dose,response effects of clove oil from Syzygium aromaticum on the root-knot nematode Meloidogyne incognita,

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2008
Susan LF Meyer
Abstract BACKGROUND: Clove oil, derived from the plant Syzygium aromaticum(L.) Merr. & Perry, is active against various organisms, and was prepared in a soy lecithin/detergent formulation to determine concentrations active against the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood. RESULTS: In microwell assays, the mean effective clove oil concentration that reduced egg hatch by 50% (EC50) was 0.097% (v/v) clove oil; the EC50 for second-stage juvenile (J2) viability was 0.145% clove oil (compared with carrier control treatments). Volatiles from 5.0% clove oil reduced nematode egg hatch in water by 30%, and decreased viability of hatched J2 by as much as 100%. Reductions were not as large with nematodes in carrier. In soil trials with J2 recovered from Baermann funnels, the EC50 = 0.192% clove oil (compared with water controls). CONCLUSION: The results demonstrated that the tested formulation is active against M. incognita eggs and J2, that the EC50 values for J2 in the microwell studies and the soil recovery tests were similar to each other and that direct contact with the clove oil is needed for optimal management results with this natural product. Published in 2007 by John Wiley & Sons, Ltd. [source]

An investigation on the correlation between rheology and morphology of nanocomposite foams based on low-density polyethylene and ethylene vinyl acetate blends

POLYMER COMPOSITES, Issue 10 2010
M. Riahinezhad
This article presents the correlation between rheology and morphology of nanocomposite foams of low-density polyethylene (LDPE), ethylene vinyl acetate (EVA), and their blends. LDPE/EVA nanocomposites were prepared via melt mixing and then foamed using batch foaming method. To assess the rheological behavior of polymer melts, frequency sweep and creep recovery tests were done. Morphology of the samples was also studied by scanning electron microscopy and X-ray diffraction. The results showed that with increase in clay content, storage modulus, complex and zero shear viscosities will be increased, which affect the foam morphology. In addition, elasticity plays an important role in foaming process, in a way that samples with more elasticity percentage have the highest cell density and the lowest cell size. POLYM. COMPOS., 31:1808,1816, 2010. © 2010 Society of Plastics Engineers. [source]