Sources of perceived sociocultural pressure on physical self-concept

Resumen tomado de la publicaci??n

Stratospheric Memory and Skill of Extended-Range Weather Forecasts

We use an empirical statistical model to demonstrate significant skill in making extended-range forecasts of the monthly-mean Arctic Oscillation (AO). Forecast skill derives from persistent circulation anomalies in the lowermost stratosphere and is greatest during boreal winter. A comparison to the Southern Hemisphere provides evidence that both the time scale and predictability of the AO depend on the presence of persistent circulation anomalies just above the tropopause. These circulation anomalies most likely affect the troposphere through changes to waves in the upper troposphere, which induce surface pressure changes that correspond to the AO.

Gas-solid reactions of single crystals: a study of the reaction of bromine with single crystals of trans-cinnamic acid and a range of its derivatives by infrared and Raman microspectroscopy

Single crystals of trans-cinnamic acid and of a range of derivatives of this compound containing halogen substituents on the aromatic ring have been reacted with 165 Torr pressure of bromine vapour in a sealed desiccator at 20 degrees C for 1 week. Infrared and Raman microspectroscopic examination of the crystals shows that bromination of the aliphatic double bond, but not of the aromatic ring, has occurred. It is demonstrated also that the reaction is truly gas-solid in nature. A time-dependent study of these reactions shows that they do not follow a smooth diffusion-controlled pathway. Rather the reactions appear to be inhomogeneous and to occur at defects within the crystal. The reaction products are seen to flake from the surface of the crystal. It is shown, therefore, that these are not single crystal to single crystal transitions, as have been observed previously for the photodimerisation of trans-cinnamic acid and several of its derivatives. It is shown that there are no by-products of the reaction and that finely ground samples react to form the same products as single crystals.

Pressure-jump X-ray studies of liquid crystal transitions in lipids

In this paper, we give an overview of our studies by static and time-resolved X-ray diffraction of inverse cubic phases and phase transitions in lipids. In 1, we briefly discuss the lyotropic phase behaviour of lipids, focusing attention on non-lamellar structures, and their geometric/topological relationship to fusion processes in lipid membranes. Possible pathways for transitions between different cubic phases are also outlined. In 2, we discuss the effects of hydrostatic pressure on lipid membranes and lipid phase transitions, and describe how the parameters required to predict the pressure dependence of lipid phase transition temperatures can be conveniently measured. We review some earlier results of inverse bicontinuous cubic phases from our laboratory, showing effects such as pressure-induced formation and swelling. In 3, we describe the technique of pressure-jump synchrotron X-ray diffraction. We present results that have been obtained from the lipid system 1:2 dilauroylphosphatidylcholine/lauric acid for cubic-inverse hexagonal, cubic-cubic and lamellar-cubic transitions. The rate of transition was found to increase with the amplitude of the pressure-jump and with increasing temperature. Evidence for intermediate structures occurring transiently during the transitions was also obtained. In 4, we describe an IDL-based 'AXCESS' software package being developed in our laboratory to permit batch processing and analysis of the large X-ray datasets produced by pressure-jump synchrotron experiments. In 5, we present some recent results on the fluid lamellar-Pn3m cubic phase transition of the single-chain lipid 1-monoelaidin, which we have studied both by pressure-jump and temperature-jump X-ray diffraction. Finally, in 6, we give a few indicators of future directions of this research. We anticipate that the most useful technical advance will be the development of pressure-jump apparatus on the microsecond time-scale, which will involve the use of a stack of piezoelectric pressure actuators. The pressure-jump technique is not restricted to lipid phase transitions, but can be used to study a wide range of soft matter transitions, ranging from protein unfolding and DNA unwinding and transitions, to phase transitions in thermotropic liquid crystals, surfactants and block copolymers.

Effect of small, acid-soluble proteins on spore resistance and germination under a combination of pressure and heat treatment

To find the range of pressure required for effective high-pressure inactivation of bacterial spores and to investigate the role of alpha/beta-type small, acid-soluble proteins (SASP) in spores under pressure treatment, mild heat was combined with pressure (room temperature to 65 degrees C and 100 to 500 MPa) and applied to wild-type and SASP-alpha(-/)beta(-) Bacillus subtilis spores. On the one hand, more than 4 log units of wild-type spores were reduced after pressurization at 100 to 500 MPa and 65 degrees C, On the other hand, the number of surviving mutant spores decreased by 2 log units at 100 MPa and by more than 5 log units at 500 MPa. At 500 MPa and 65 degrees C, both wild-type and mutant spore survivor counts were reduced by 5 log units. Interestingly, pressures of 100, 200, and 300 MPa at 65 degrees C inactivated wild-type SASP-alpha(+)/beta(+) spores more than mutant SASP-alpha(-)/beta(-) spores, and this was attributed to less pressure-induced germination in SASP-alpha(-)/beta(-) spores than in wild-type SASP-alpha(+)/beta(+) spores. However, there was no difference in the pressure resistance between SASP-alpha(+)/beta(+) and SASP-alpha(-)/beta(-) spores at 100 MPa and ambient temperature (approximately 22 degrees C) for 30 min. A combination of high pressure and high temperature is very effective for inducing spore germination, and then inactivation of the germinated spore occurs because of the heat treatment. This study showed that alpha/beta-type SASP play a role in spore inactivation by increasing spore germination under 100 to 300 MPa at high temperature.

Kinetics of high pressure facilitated starch gelatinisation in Thai glutinous rice

The combined effect of pressure and temperature on the rate of gelatinisation of starch present in Thai glutinous rice was investigated. Pressure was found to initiate gelatinisation when its value exceeded 200 MPa at ambient temperature. On the other hand, complete gelatinisation was observed at 500 and 600 MPa at 70 degrees C, when the rice was soaked in water under these conditions for 120 min. A first-order kinetic model describing the rate of gelatinisation was developed to estimate the values of the rate constants as a function of pressure and temperature in the range: 0.1-600 MPa and 20-70 degrees C. The model, based on the well-known Arrhenius and Eyring equations, assumed the form [GRAPHICS] The constants k(0), E-a, and Delta V were found to take values: 31.19 s(-1), 37.89 kJ mol(-1) and -9.98 cm(3) mol(-1), respectively. It was further noted that the extent of gelatinisation occurring at any time, temperature and pressure, could be exclusively correlated with the grain moisture content. (c) 2006 Elsevier Ltd. All rights reserved.

Iron and zinc status in multiple sclerosis patients with pressure sores

Measurements of weighted dietary intakes and plasma determinations of albumin, iron, zinc, ascorbic acid and TIBC were carried out on twenty female multiple sclerosis patients in a long-stay hospital for disabled people. The group included ten patients with a recent history of pressure sores, closely matched with ten patients without pressure sores. Mean daily intake of carbohydrate was found to be higher in the non-pressure sore group whilst intake of zinc was lower in this group. Intakes of all other nutrients were comparable between the two groups. For both groups, intakes of energy, folate, vitamin D, iron and zinc were less than recommended values. Mean plasma levels of albumin and iron were towards the lower limit of the normal range, whilst that for zinc was considerably less than the normal range. Plasma TIBC was slightly above the normal range. Levels of plasma iron and zinc were significantly lower in the pressure sore group. The data indicate that severely disabled hospitalized patients with multiple sclerosis may be at risk of poor nutritional status. The results suggest that in the presence of pressure sores, there are increased requirements for specific nutrients, notably zinc and iron. Consideration is given to the possible value of supplementation of these individuals.

Thermal and high hydrostatic pressure inactivation of myrosinase from green cabbage: a kinetic study

Myrosinase, a family of enzymes which coexist with glucosinolates in all Brassica vegetables, catalyses the hydrolysis of glucosinolates to yield compounds that can have beneficial effects on human health. In this study, the thermal and pressure inactivation of myrosinase from green cabbage was kinetically investigated. Thermal inactivation started at 35 C and inactivation kinetics was studied in the temperature range 35–55 C. Thermal inactivation of green cabbage myrosinase followed the well known consecutive step model. Pressure inactivation started at 300 MPa, even at 10 C, and the consecutive step model effectively described pressure inactivation in the range 300–450 MPa at 10 C. The combined effects of applying various pressures and temperatures on myrosinase inactivation kinetics were studied in the ranges 35–50 C and, 100–400 MPa. The inactivation followed first-order kinetics at all of the applied combinations. This study demonstrates that myrosinase from green cabbage is highly susceptible to both thermal and high pressure processing. Furthermore, it is also noted that myrosinase stability during processing appears to vary widely between different Brassica species.

Characterization of a Listeria monocytogenes Scott A isolate with high tolerance towards high hydrostatic pressure

An isolate of L. monocytogenes Scott A that is tolerant to high hydrostatic pressure (HHP), named AK01, was isolated upon a single pressurization treatment of 400 MPa for 20 min and was further characterized. The survival of exponential- and stationary-phase cells of AK01 in ACES [N-(2-acetamido)-2-aminoethanesulfonic acid] buffer was at least 2 log units higher than that of the wild type over a broad range of pressures (150 to 500 MPa), while both strains showed higher HHP tolerance (piezotolerance) in the stationary than in the exponential phase of growth. In semiskim milk, exponential-phase cells of both strains showed lower reductions upon pressurization than in buffer, but again, AK01 was more piezotolerant than the wild type. The piezotolerance of AK01 was retained for at least 40 generations in rich medium, suggesting a stable phenotype. Interestingly, cells of AK01 lacked flagella, were elongated, and showed slightly lower maximum specific growth rates than the wild type at 8, 22, and 30°C. Moreover, the piezotolerant strain AK01 showed increased resistance to heat, acid, and H2O2 compared with the wild type. The difference in HHP tolerance between the piezotolerant strain and the wild-type strain could not be attributed to differences in membrane fluidity, since strain AK01 and the wild type had identical in situ lipid melting curves as determined by Fourier transform infrared spectroscopy. The demonstrated occurrence of a piezotolerant isolate of L. monocytogenes underscores the need to further investigate the mechanisms underlying HHP resistance of food-borne microorganisms, which in turn will contribute to the appropriate design of safe, accurate, and feasible HHP treatments.

Production of milk foams by steam injection: the effects of steam pressure and nozzle design

Foam properties depend on the physico-chemical characteristics of the continuous phase, the method of production and process conditions employed; however the preparation of barista-style milk foams in coffee shops by injection of steam uses milk as its main ingredient which limits the control of foam properties by changing the biochemical characteristics of the continuous phase. Therefore, the control of process conditions and nozzle design are the only ways available to produce foams with diverse properties. Milk foams were produced employing different steam pressures (100-280 kPa gauge) and nozzle designs (ejector, plunging-jet and confined-jet nozzles). The foamability of milk, and the stability, bubble size and texture of the foams were investigated. Variations in steam pressure and nozzle design changed the hydrodynamic conditions during foam production, resulting in foams having a range of properties. Steam pressure influenced foam characteristics, although the net effect depended on the nozzle design used. These results suggest that, in addition to the physicochemical determinants of milk, the foam properties can also be controlled by changing the steam pressure and nozzle design.

Influence of Fluid Concentration on the Elevation of Boiling Point of Blackberry Juice

The rise in boiling point of blackberry juice was experimentally measured at soluble solids concentrations in the range of 9.4 to 58.4Brix and pressures between 4.9 103 and 9.0 104 Pa (abs.). Different approaches to representing experimental data, including the Duhring`s rule, a model similar to Antoine equation and other empirical models proposed in the literature were tested. In the range of 9.4 to 33.6Brix, the rise in boiling point was nearly independent of pressure, varying only with juice concentration. Considerable deviations of this behavior began to occur at concentrations higher than 39.1Brix. Experimental data could be best predicted by adjusting an empirical model, which consists of a single equation that takes into account the dependence of rise in boiling point on pressure and concentration.

Development of a novel microextraction by packed sorbent-based approach followed by ultrahigh pressure liquid chromatography as a powerful technique for quantification phenolic constituents of biological interest in wines

A novel analytical approach, based on a miniaturized extraction technique, the microextraction by packed sorbent (MEPS), followed by ultrahigh pressure liquid chromatography (UHPLC) separation combined with a photodiode array (PDA) detection, has been developed and validated for the quantitative determination of sixteen biologically active phenolic constituents of wine. In addition to performing routine experiments to establish the validity of the assay to internationally accepted criteria (linearity, sensitivity, selectivity, precision, accuracy), experiments are included to assess the effect of the important experimental parameters on the MEPS performance such as the type of sorbent material (C2, C8, C18, SIL, and M1), number of extraction cycles (extract-discard), elution volume, sample volume, and ethanol content, were studied. The optimal conditions of MEPS extraction were obtained using C8 sorbent and small sample volumes (250 μL) in five extraction cycle and in a short time period (about 5 min for the entire sample preparation step). The wine bioactive phenolics were eluted by 250 μL of the mixture containing 95% methanol and 5% water, and the separation was carried out on a HSS T3 analytical column (100 mm × 2.1 mm, 1.8 μm particle size) using a binary mobile phase composed of aqueous 0.1% formic acid (eluent A) and methanol (eluent B) in the gradient elution mode (10 min of total analysis). The method gave satisfactory results in terms of linearity with r2-values > 0.9986 within the established concentration range. The LOD varied from 85 ng mL−1 (ferulic acid) to 0.32 μg mL−1 ((+)-catechin), whereas the LOQ values from 0.028 μg mL−1 (ferulic acid) to 1.08 μg mL−1 ((+)-catechin). Typical recoveries ranged between 81.1 and 99.6% for red wines and between 77.1 and 99.3% for white wines, with relative standard deviations (RSD) no larger than 10%. The extraction yields of the MEPSC8/UHPLC–PDA methodology were found between 78.1 (syringic acid) and 99.6% (o-coumaric acid) for red wines and between 76.2 and 99.1% for white wines. The inter-day precision, expressed as the relative standard deviation (RSD%), varied between 0.2% (p-coumaric and o-coumaric acids) and 7.5% (gentisic acid) while the intra-day precision between 0.2% (o-coumaric and cinnamic acids) and 4.7% (gallic acid and (−)-epicatechin). On the basis of analytical validation, it is shown that the MEPSC8/UHPLC–PDA methodology proves to be an improved, reliable, and ultra-fast approach for wine bioactive phenolics analysis, because of its capability for determining simultaneously in a single chromatographic run several bioactive metabolites with high sensitivity, selectivity and resolving power within only 10 min. Preliminary studies have been carried out on 34 real whole wine samples, in order to assess the performance of the described procedure. The new approach offers decreased sample preparation and analysis time, and moreover is cheaper, more environmentally friendly and easier to perform as compared to traditional methodologies.

A new and improved strategy combining a dispersive-solid phase extraction-based multiclass method with ultra high pressure liquid chromatography for analysis of low molecular weight polyphenols in vegetables

This paper reports on the development and optimization of a modified Quick, Easy, Cheap Effective, Rugged and Safe (QuEChERS) based extraction technique coupled with a clean-up dispersive-solid phase extraction (dSPE) as a new, reliable and powerful strategy to enhance the extraction efficiency of free low molecular-weight polyphenols in selected species of dietary vegetables. The process involves two simple steps. First, the homogenized samples are extracted and partitioned using an organic solvent and salt solution. Then, the supernatant is further extracted and cleaned using a dSPE technique. Final clear extracts of vegetables were concentrated under vacuum to near dryness and taken up into initial mobile phase (0.1% formic acid and 20% methanol). The separation and quantification of free low molecular weight polyphenols from the vegetable extracts was achieved by ultrahigh pressure liquid chromatography (UHPLC) equipped with a phodiode array (PDA) detection system and a Trifunctional High Strength Silica capillary analytical column (HSS T3), specially designed for polar compounds. The performance of the method was assessed by studying the selectivity, linear dynamic range, the limit of detection (LOD) and limit of quantification (LOQ), precision, trueness, and matrix effects. The validation parameters of the method showed satisfactory figures of merit. Good linearity (View the MathML sourceRvalues2>0.954; (+)-catechin in carrot samples) was achieved at the studied concentration range. Reproducibility was better than 3%. Consistent recoveries of polyphenols ranging from 78.4 to 99.9% were observed when all target vegetable samples were spiked at two concentration levels, with relative standard deviations (RSDs, n = 5) lower than 2.9%. The LODs and the LOQs ranged from 0.005 μg mL−1 (trans-resveratrol, carrot) to 0.62 μg mL−1 (syringic acid, garlic) and from 0.016 μg mL−1 (trans-resveratrol, carrot) to 0.87 μg mL−1 ((+)-catechin, carrot) depending on the compound. The method was applied for studying the occurrence of free low molecular weight polyphenols in eight selected dietary vegetables (broccoli, tomato, carrot, garlic, onion, red pepper, green pepper and beetroot), providing a valuable and promising tool for food quality evaluation.

Changes on emitter discharge under different water temperature and pressure

The study was conducted at the Research Laboratory of Hydraulic and Irrigation Group in the Rural Engineering Department, Technical University of Madrid (Universidad Politecnica de Madrid), Madrid, Spain. Water temperatures of 20, 30, 40 degrees C and system pressures often encountered in irrigation practices of 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 and 200 k Pa were applied to determine the effects of different water temperatures and pressures on emitter discharge. Non-pressure compensating in-line emitter which has turbulent flow regime with a long-path (labyrinth), emitter discharge was 4 L h(-1) at system pressure of 100 kPa according to the manufacturer recommended, was used. Emitters were spaced 20 cm along the drip laterals with 16 mm diameter. Discharge equations and coefficients of variation related to temperatures of 20, 30 and 40 degrees C were obtained as q = 0.375H(0.51), q = 0.358H(0.52), q = 0.346H(0.53) and 2.68, 2.09, 3.65, respectively. Discharge of the emitter was affected by different system pressures and increased as potentially (R = 0993-0996). In general. the emitter discharge increased with increasing temperature. However, especially in the common system pressures of 90-120 k Pa, differences of obtained emitter discharges between the different water temperatures were not significant (1%).

Effects of gamma-irradiation on caprolactam level from multilayer PA-6 films for food packaging: Development and validation of a gas chromatographic method

A gas chromatographic method to determine caprolactam in multilayer PA-6 films used for meat foodstuffs and cheese was developed and validated. A wide linear range (0.8-400 mu g/ml), RSD <= 4.1% and recovery higher than 90.0% were obtained for the chromatographic system, while precision and accuracy of the method showed RSD <= 3.8%, recovery from 95.5-100.0% and LOQ of 32 mu g/g. Irradiated (3, 7 and 12 kGy) and non-irradiated commercial films were analyzed. Most of them increased caprolactam levels with the increase of irradiation doses. (C) 2008 Elsevier Ltd. All rights reserved.