Effect Of Preparation Procedure Research Articles

Supported VPO catalysts for selective oxidation of butane III: Effect of preparation procedure and SiO 2 support

The effects of the nature of silica support and removal of soluble vanadium species by ethanol on the catalytic properties of silica-supported VPO catalysts were investigated. Ethanol preferentially removes V +5 species. For a silica-supported sample of P/ V ratio much lower than two, ethanol treatment resulted in a sample of higher P/ V ratio and higher selectivity for maleic anhydride in butane oxidation. The crystalline VPO phases formed differed on a hydrophobic vs. hydrophilic silica. (VO) 2P 2O 7 could be formed more easily on the former support. Interestingly, for all silica-supported catalysts, the maleic anhydride selectivity depended much more strongly on the P/ V ratio than on the method of preparation, the nature of the silica, or the crystalline VPO phase present.

Effects of preparation procedures, packaging and storage on nutrient retention in peeled potatoes

The effects of preparation procedures and packaging on vitamin C, dietary fibre, sugars, ash and moisture contents were studied in prepeeled packaged potatoes during two cultivation seasons. The potato cultivars Bintje, Van Gogh and Nicola were studied. Potatoes of the Nicola cultivar had the highest initial vitamin C and sugar contents. Retention of nutrient contents in packaged, prepeeled potatoes was very good after a 7-day storage period. Vitamin C contents were higher in packaged potatoes than in fresh tubers when ascorbic acid was used in the washing solution but the levels decreased during the 7-day storage period. When calcium chloride was added as well into the washing solution vitamin C contents remained high throughout the storage period. These results show that it is possible to preserve the nutritional contents of packaged potatoes over a 7-day storage period. Cooking decreased vitamin C contents by about 30% and keeping the potatoes hot for 1 h after cooking decreased vitamin C contents a further 10%. © 1998 SCI.

Effects of preparation procedures, packaging and storage on nutrient retention in peeled potatoes

Effects of preparation procedures, packaging and storage on nutrient retention in peeled potatoes

The relation between preparation, microstructure and mechanical properties of spherical yttria-zirconia powders

The effect of preparation procedure on the behaviour of spherical yttria-zirconia powders during heat treatment and also on their resultant properties has been studied. The powders were prepared from coprecipitated hydrous zirconia gels and also from precalcined material using a spray drying technique. The powders were characterised by determining the changes in morphology, specific surface area, pore size distribution, porosity and compressive strength that occurred due to heat treatment. It has been found that the characteristics of the powders were affected greatly by the following steps of the preparation procedure: (i) washing the original gels with organic liquid, (ii) drying and milling of the gels, and (iii) precalcination. The enlargement of the modal pore size of the granules observed during heat treatment was dependent on the width of the pore size distribution and on the ratio between pore size and grain size. The compressive strength of the granules was dependent on the porosity, particle size and flaws present in the sintered granules.

Effects of the preparation procedure and additives on surface texture of nickel and cobalt oxides as final decomposition products of nickel and cobalt oxysalts

The effects of preparation procedure and readily decomposable salt additives, namely (NH 2 ) 2 CO and NH 4 NO 3 , on the texture of NiO and Co 3 O 4 produced by calcination of Ni(NO 3 ) 2 ·6H 2 O and Co(NO 3 ) 2 ·6H 2 O were investigated. Textural characteristics were assessed via analysis of nitrogen adsorption isotherms, using a number of widely-accepted methods. The thermal genesis courses of NiO and Co 3 O 4 , from additive-containing and additive-free oxide precursors were explored using thermogravimetry, differential thermal analysis and X-ray diffractometry (XRD). The results of surface texture and XRD analyses were largely in agreement and showed that pores are modified. An impregnation procedure using salt additives to NiO and Co 3 O 4 resulted in a marked increase of surface area (from 23 to 65 m 2 g −1 for NiO and from 18 to 82 m 2 g −1 for Co 3 O 4 ). This increase is most likely due to the evolved gases and the consequent fragmentation of particles and the widening of pores.

Effect of preparation procedure, oxygen concentration and water on the reduction of nitric oxide by ammonia over chromia selective catalytic reduction catalysts

The effects of preparation procedure, oxygen concentration and water on the reaction of nitric oxide and ammonia over chromia catalysts prepared by thermal treatment of chromium hydroxide have been determined. Analyses were performed using a combination of mass spectrometry, Fourier transform infrared spectroscopy and gas chromatography. Thermogravimetric and differential thermal analysis techniques show that the temperature at which transformation of amorphous chromia to the α-Cr 2O 3 phase occurs is dependent on the gaseous atmosphere during the heat-treatment process, and increases in the order oxygen, nitrogen and hydrogen. When heating the catalyst precursorin hydrogen, the chromia material remains amorphous for temperatures below about 420°C. Samples heated above ca. 470°C are highly crystalline. The crystallinity of the chromia material is the most significant factor in determining the activity, and selectivity, of the resulting catalysts for the NO/NH 3 reaction. Amorphous chromia catalysts prepared with a two order-of-magnitude difference in ammonia addition rate show similar performances. Kenetic orders in oxygen to produce both nitrogen and nitrous oxide have been determined. Amorphous chromia shows a much higher order in oxygen for nitrogen formation than does α-Cr 2O 3. However, for nitrous oxide formation, the orders are approximately the same for both morphologies. Addition of 1.5% H 2O vapour decreases nitric oxide and ammonia conversions over amorphous chromia for all temperatures below 275°C, whereas for α-Cr 2O 3, the effect varies with reaction temperature. For amorphous chromia the addition of water substantially decreases the formation of nitrous oxide.

Outlines of the ion exchange characteristics of hydrous oxides

This work gives a critical review of the behaviour of hydrous oxides as ion exchangers. The various physicochemical properties of this important class of adsorbents and the effect of preparation procedures are summarized. Data on the ion exchange kinetics and thermodynamics are presented and discussed. Selectivity is also discussed in terms of the different parameters. Both aqueous and mixed media are considered. In addition, the different sorption mechanisms, some relevant sorption models, and potential applications in chemical separations are given. Moreover, this review attempts to point to the experimental and theoretical confusions now alarmingly met in the literature.

Dental implant materials. I. Some effects of preparative procedures on surface topography.

The effect of different treatments for preparing implant materials was examined by scanning electron microscopy and by contact angle measurements. The materials examined were Ti6A14V alloy, Co-Cr-Mo alloy, A12O3, and synthetic hydroxyapatite. Samples were prepared with solid or porous surfaces of these materials. These were detergent-cleaned and then either autoclaved (steam sterilization), radiation-sterilized, nitric acid-etched, or plasma-cleaned. The results of wettability studies indicated marked changes in surface energy corresponding to the different preparation methods, and differences in surface morphology were also observed. These differences could have significant consequences on in vivo implant behaviour as mediated by tissue-implant interactions.

Effect of Preparation Procedures and Storage Parameters on Quality Retention of Salad‐cut Lettuce

ABSTRACTPiece‐size reduction, which is required in preparing lettuce for salads, shortens storage life of cut lettuce as compared to uncut head lettuce. Cellular fluids, released during cutting, are removed by rinsing with water, followed by centrifugation to remove added surface moisture. Extended centrifugation can cause desiccation of product, which may be beneficial under certain conditions. Other methods of water removal, such as blotting or forced air did not seem practical. During storage green pigmentation decreased in salad‐cut lettuce. Optimum cold storage was obtained by packaging the cut‐lettuce in pouches that had been slightly evacuated and contained a small amount of carbon monoxide.

Processing, Perovskite Phase Development, and Dielectric Properties for Sol-Gel Derived Pb[(Mg1/3Nb2/3)0.9Ti0.1]O3 Thin Layers

ABSTRACTAlkoxide-based solutions were synthesized and used to prepare Pb[(Mg1/3Nb2/3)0.90Ti0.10]O3 (90PMNT) thin layers on platinized Si. A multilayering spin casting method was used. The effects of preparation procedure, additives, and intermediate heat-treatments on perovskite phase content, microstructure development and dielectric properties are reported. The greatest perovskite content (∼99%) and the best dielectric properties (K ≈ 1500–2000, tan∂ ≈ 0.03 at 100 kHz) resulted from rapid thermal processing of individual layers at 800°C. Polarization-reversal measurements are also reported.

Effects of preparation procedures on the ultrastructural morphology of blood

The development and testing of (ecological) models require continuous control and adaptation of the simulator to measured data. Optimisation techniques, sensitivity and uncertainty analysis are important tools to automate these validation steps and support modellers to understand and interpret simulation results in terms of their reliability.Since ecological models simulate complex environmental processes, the models developed exhibit a high degree of detail. As a result, the required CPU time is substantial whilst at the same time these models can no longer be analytically analysed and optimised. Therefore representative sampling techniques are often used requiring a high number of model runs. Hence, the model run time and the number of samples needed to create a representative range are the driving factors that determine the total required time for validation.As a consequence, it is therefore indispensable to parallelise parts of the code and run them on more than one processing unit. Therefore, the aim of this study is to show the ease of parallelisation within the statistical software R using the package Rmpi. We present the parallelisation of three different applications (optimisation, Bayesian calibration, sampling from distributions), using our complex ecosystem model LandscapeDNDC. We were able to run the Bayesian Calibration at a computing cluster using 24 CPU's in 11.8 days opposed to 236.7 days when using only one CPU. This is an acceleration of the evaluation process by a factor of approximately 20.

Effects of preparative procedures and of cell activation on flow of white cells through micropore filters

Using newly developed filtration techniques to analyse the flow resistance of white blood cells (WBC), the effects of preparative procedures and of various treatments (including activation) have been tested. Flow rates of WBC were measured using both 5 and 8 micron pore filters. It was found that EDTA was the anticoagulant of choice over heparin and sodium citrate, and that calcium-containing media should be avoided because they promoted cell-cell aggregation. Exposure to density separation media did not significantly alter filtration rates, but storage of prepared WBC for even 1 h caused deterioration in flow. Storage of whole blood before preparation of the WBC had a much lesser effect. Storage appeared to be linked to cell activation, and use of the activating agents phorbol ester (PE, 4.5 x 10(6) M/l) and f-methyl-leucyl-phenylalanine (FMPL, 10(-7) and 10(-9) M/l) also increased WBC resistance to pore transit. The effect of PE was greater, causing rapid pore blockage, but was non-specific, while the lesser effect of FMLP was restricted to granulocytes and was concentration dependent. Cell volume was increased by these agents, but measurement of the filterability of hypotonically swollen granulocytes showed that volume changes alone only partly explained the activation effects. These results suggest that activation in vivo would have a significant rheological effect, detectable by filtration methods.

Effect of preparative procedures on ghostcells from bovine erythrocytes.

Several methods for the preparation of "white ghosts" or "resealed ghosts" were described in the recent literature. This article compares three methods to prepare white, resealed ghosts from bovine erythrocytes based on the principle of hypotonic lysis. The methods described differ by the removal of hemoglobin from the empty cells. The main difference between the standard centrifugation, the gelfiltration and the hollow-fibre diafiltration is the mechanical stress on the leaky membranes after swelling in hypotonic media. Mean cellular volumes, rates of potassium-efflux and the access of impermeable dyes to cytoplasmatic proteins are criteria to differentiate between ghostcell-populations.

Does corrosion matter?

Does corrosion matter?

Effects of preparative procedures on the volume and content of resealed red cell ghosts

The effects of variations in preparative procedures on the volume and content of resealed red cell ghosts have been investigated. Following hypotonic lysis at 0°C, and after a variable delay time ( t d, concentrated buffer was added to restore isotonicity; resealing was then induced by incubation at 37°C for one hour. Using this procedure, both the resealed ghost volume and the residual hemoglobin (Hb) content decreased for increasing t d. If ghosts were maintained at 0°C (i.e., no 37°C incubation), they remained nearly spherical until isotonicity was restored. Their volume then fell abruptly, but subsequently increased toward an intermediate level. The fall in volume was greater and the final level achieved was smaller for longer delay times. At 0°C, return to isotonicity also halted the otherwise gradual loss of residual Hb from unsealed ghosts. In addition, ghosts with internal osmolality of 40 to 300 mosmol/kg were prepared by adding different amounts of concentrated buffer before resealing for one hour at 37°C. Under these conditions, the final ghost volume was inversely related to the resealing osmolality (i.e., lower osmolality yielded a larger volume). Ghost volume also increased, along with Hb content, if the quantity or concentration of the red cell suspension added to the lysing medium was increased. We conclude that resealed ghost volume is influenced by the ratio of lysate to resealing medium osmolality and by the colloid osmotic pressure of the residual ghost Hb. These data indicate methods by which ghosts with desired characteristics can be prepared, and have potential application for studies of ghost mechanical and biophysical behavior.

Effects of preparative procedures on the sedimentation behaviour of 40-S ribosomal subunits

The sedimentation characteristics on sucrose gradients of derived 40-S subunits from rat liver depend on the ionic conditions used in their preparation. Following the procedure of Wettenhall, R.E.H., Wool, I.G. and Sherton, C.C. (Biochemistry 12 (1973) 2403–2411) in which 12.5 mM Mg 2+ is present throughout the preparation of the subunits, sucrose gradients of the 40-S fraction show two peaks consistent with the presence of a mixed and non-interchanging population of monomers and dimers. By contrast, when ribosomes and subunits are prepared in 2 mM Mg 2+ it is shown here that 40-S subunits sediment as a single peak at a rate intermediate between that of monomers and dimers as established by prior fixation with glutaraldehyde or formaldehyde - a phenomenon observed by Spirin, A.S., Belitsina, N.V. and Lishnevskaya, E.B. (FEBS Lett. 24 (1972) 219–224) for the Escherichia coli 30-S–50-S couple but not previously shown for subunits of eukaryotic origin. Under conditions of low [Mg 2+] it is suggested that the subunits are of a uniform population capable of dimerization and that equilibrium can continue during sedimentation. In the present experiments it was not possible to find tRNA in 40-S subunits as shown by Wettenhall et al. By fixation before sedimentation the relative proportions of monomers and dimers of 40 S incubated under a variety of conditions was determined. Warming from 0 to 37°C increased the proportion of monomers markedly, but variation of [Mg 2+] had little effect. Incubation with albumin or tRNA or spermine also had little effect, but addition of ribosomal salt-wash increased the proportion of monomers. It seems most likely that many of the 40-S subunits prepared in 12.5 mM Mg 2+ have initiation factors or other proteins bound to them which prevent dimerization, but that subunits prepared at any stage with buffer containing only 2 mM Mg 2+ have lost these proteins and therefore are able to dimerize to a degree depending on concentration. Different relative proportions of monomers and dimers were observed depending on whether glutaraldehyde or formaldehyde was used as fixative. Reasons are suggested for believing that formaldehyde is to be preferred to glutaraldehyde for fixation in experiments of this nature.

Morphometric analysis of the corpus luteum of 16-day pregnant rats: the effect of preparative procedures on volume of luteal cells, interstitial, and vascular compartments.

The volumes of the major tissue compartments, vascular space, interstitial space, and luteal cells, in the corpus luteum (CL) of 16-day pregnant rats were determined morphometrically after different fixation procedures. Ovaries were fixed by perfusion at physiologic pressures (PF), by immersion directly in fixative (IF), by immersion after clamping blood vessels to prevent escape of blood (IFC), or by immersion after administration of heparin to prevent blood clotting (IFH). Three CL in each of eight ovaries were examined for each fixation method. Total volumes were significantly larger in CL fixed by PF and IFC, and approximated physiologic volumes as assessed from frozen ovaries. Perfusion-fixed CL had significantly larger vascular and interstitial spaces and smaller cell volumes than immersion-fixed CL. Capillary surface area varied significantly between the four groups in accordance with absolute volume of vascular space. Estimated numbers of endothelial cells and amounts of connective tissue differed significantly, presumably due to difficulties in identifying these components in immersion-fixed CL with collapsed vessels. The fixation methods used caused substantial fluid shifts between the three major compartments. A theoretical approach for considering these shifts and the likely physiologic situation was developed.

Effects of preparation procedure on the surface properties of rhodium supported on γ-alumina

The decomposition of rhodium(III) nitrate, chloropentamminerhodium(III) chloride and rhodium(III) sulphite in atmospheres of hydrogen, nitrogen and nitrogen (80%)+ oxygen (20%) have been investigated by thermogravimetric analysis with the salts either pure or impregnated onto a γ-alumina support. The decomposition of rhodium(III) sulphite failed to give dispersions of rhodium metal on alumina but the reduction of the other salts to Rh0 was complete in nitrogen or hydrogen at temperatures between 400 and 690 K.Hydrogen and CO uptake data have shown that rhodium(III) nitrate led to a more finely divided dispersion of metal than did chloropentamminerhodium(III) chloride. Infrared spectra of CO absorbed on the Rh/Al2O3 dispersions were consistent with this conclusion. The effects of sintering and oxygen adsorption on the infrared spectra are reported. Linear and bridge-bonded CO were formed on exposed metal planes or two-dimensional rafts at Rh0 sites which were also active for the chemisorption of oxygen. Gem-dicarbonyl species were formed at monatomically dispersed rhodium sites or edge sites in rafts, both of which had cationic character through interaction with the alumina support. These sites were not active for the adsorption of oxygen.

Structural Aspects of Protein Accumulation in Developing Pea Cotyledons. Iv. Effects of Preparative Procedures on Ultrastructural Integrity.

The pea storage proteins legumin and vicilin have previously been shown to be deposited in the vacuoles of cells of young developing cotyledons. By electron microscopy, the appearance of vacuole contents, and in particular of the peripheral protein deposits, are known to vary even in controlled and reproducible conditions of plant growth. This observation suggests an influence of specimen preparation on appearance. Different fixative solutions used on developing pea-seed cotyledons affected the appearance of the cytoplasm and its contents only slightly. The appearance of vacuole contents was greatly modified by the type of buffer used as a fixative vehicle and by osmotic conditions induced by added sucrose, and less by the primary fixative used. From a comparison with living protoplasts from cotyledon cells, it was concluded that the non-membrane-bound peripheral protein deposits are not artefacts of preparation. It is suggested that sucrose may play a role in the transition of vacuoles to protein bodies.

Rheological Properties of Prune Juice

ABSTRACTThe effect of preparation procedures, raw material and additives on prune juice viscosity was investigated. Prune juice preparation procedure had the greatest effect on juice viscosity of any parameters studied, with the disintegration process producing juice having higher viscosity than the diffusion process. Juice viscosity decreased during elevated storage temperatures. Also, prune size and maturity influenced viscosity, with smaller prunes harvested early in the season producing juice with higher viscosities. In diffusion juice extraction, the first leach product had a lower viscosity, lighter color and higher potassium content that the rest. Prune concentrate over 45° brix exhibited dilatant properties.