Osmotic Pressure Method Research Articles

Design of Salted Egg Maker by Using PLC Based on Osmotic Pressure Method

Salted egg is one of the egg types that has a lot of devotees because it tastes a little salty and savory. Salted eggs are usually homemade in various regions. The easy process of making them has attracted many people to do so. This study developed a PLC-based on automatic system for a salted egg maker using the osmotic pressure method to accelerate the opening of the semi-permeable membrane on duck eggshells so that the salting mixture seeps into the eggs more quickly. It was carried out in an osmotic pool containing water and acetic acid at a concentration of 5%. The data collection process in designing the salted egg maker consisted of evaluating the performance of photoelectric sensors, proximity sensors, temperature controller, thermostat set point, baking time, and salted egg durability test. The results of the tests indicated that the time needed to make salted eggs from raw eggs to cooked eggs only took 36 minutes using the machine designed. Additionally, the presented salted egg maker reveals the short making time, and long salted egg durability. altogether revealing full potential to be easily used for practical applications.

An in silico osmotic pressure approach allows characterization of pressure-area isotherms of lipid monolayers at low molecular areas.

Surface pressure-area isotherms of lipid monolayers at the air-water interface provide essential information about the structure and mechanical behaviour of lipid membranes. These curves can be readily obtained through Langmuir trough measurements and, as such, have been collected for decades in the field of membrane biochemistry. However, it is still challenging to directly observe and understand nanoscopic features of monolayers through such experiments, and molecular dynamics (MD) simulations are generally used to provide a molecular view of such interfaces. In MD simulations, the surface pressure-area (Π-A) isotherms are generally computed using the Kirkwood-Irving formula, that relies on the evaluation of the pressure tensor. This approach, however, has intrinsic limitations when the molecular area in the monolayer is low (typically < 60 Å2 per lipid). Recently, an alternative method to compute Π-A isotherms of surfactants, based on the calculation of the three-dimensional osmotic pressure via the implementation of semipermeable barriers was proposed. In this work, we investigate the feasibility of this approach for long-chain surfactants such as phospholipids. We identify some discrepancies between the computed values and experimental results, and we propose a semi-empirical correction based on the molecular structure of the surfactants at the monolayer interface. To validate the potential of this new approach, we simulate several phosphatidylcholine and phosphatidylethanolamine lipids at various temperatures using all-atom and coarse-grained force fields, and we compute the corresponding Π-A isotherms. Our results show that the Π-A isotherms obtained using the new method are in very good agreement with experiments and far superior to the canonical pressure tensor-based method at low molecular areas. This corrected osmotic pressure method allows for accurate characterization of the molecular packing in monolayers in various physical phases.

Durable Polyelectrolyte Microcapsules with Near-Infrared-Triggered Loading and Nondestructive Release of Cargo.

Microcapsules formed using a "layer-by-layer" alternating deposition of oppositely charged polyelectrolytes on sacrificial templates have reached high interest because of their facile fabrication procedure using a broad range of materials and tailored properties. However, their practical applications as microcarriers are limited as the capsules commonly suffer from low mechanical stability that can be enhanced by chemical or physical crosslinking but at the expense of decreasing permeability of the capsules' walls. It is demonstrated here that the incorporation of multiwalled carbon nanotubes in a relatively small amount (3.5%) arranged in the direction perpendicular to the capsules' walls led to an almost 20-fold increase of the apparent elastic modulus of the microcapsules as shown using the osmotic pressure method. Importantly, the introduced carbon nanotubes due to their absorption in the near-infrared region and specific arrangement enabled also a light-triggered increase of permeability of the capsules in a reversible, nondestructive manner as shown using fluorescently labeled dextrans of various molar masses. Such results imply durability and facile loading/unloading of the microcapsules that are both crucial for their practical applications as microcontainers and microreactors.

Evidence, Determination, and Implications of Membrane-Independent Limiting Flux in Forward Osmosis Systems.

A stepwise method for determining limiting flux and limiting osmotic pressure and a constant osmotic pressure method to validate the limiting flux were developed. First, five of the most commonly used FO membranes were characterized for water permeability ( A), solute permeability ( B), and structural parameter ( S). During both stepwise and constant osmotic pressure fouling experiments, membrane fouling constrained water flux to a singular, common upper limit, the limiting flux, for all membranes despite very different A and A/ B values for the membranes. Conversely, there was not an upper limit to reverse salt flux. It was observed that reverse salt flux increases as S decreases; however, this does not mean that higher S values are desirable. Higher S values (> ∼600 μm) also increase dilutive internal concentration polarization, which is recognized as the major impediment to achieving high FO water flux. For osmotic processes where membrane fouling occurs, membrane transport parameters A and B may not be useful performance indicators, and the goal of improving water flux by developing highly permeable, highly selective membranes may not be realistic. Instead, optimizing fouling mitigation strategies, hydrodynamics at the membrane surface, and membrane module configuration may be more promising alternatives for improving performance.

Contact angle of water on iron ore fines: Measurement and analysis

The relative contact angle (?RCA) for seven iron ore fines was measured by using Washburn Osmotic Pressure method under laboratory conditions. By choosing cyclohexane as the reference that can perfectly wet iron ore particles, the relative contact angles were measured and varied from 57? to 73?. With the volume % of goethite (?G) as the variable, a new model for relative contact angle was developed. The expected relative contact angle for pure goethite is about 56?, while that for goethite free samples is about 77?. Physical properties, such as surface morphology (SMI) and pore volume (Vpore) can influence the relative contact angle. The ?G can be expressed as a function of SMI and VPore. Thus, we inferred that the relative contact angle is a function of ?G for the iron ores used. The measured relative contact angles were found to be in good agreement (Radj 2 &gt;0.97) with the calculated ones based on the research from Iveson, et al. (2004). Comparing with the model developed by Iveson et al.(2004), the new model for contact angle proposed in this paper is similar, but more detailed with two meaningful physical parameters. The modification of physicochemical properties on iron ores would be another topic in the further study on granulation.

Preparation of samples for electron microscopy by high osmotic pressure method

Preparation of samples for electron microscopy by high osmotic pressure method

Osmotic pressure method to measure salt induced folding/unfolding of bovine serum albumin

A new approach has been developed to monitor protein folding by utilizing osmotic pressure and a range of salt concentrations in a well characterized protein, bovine serum albumin (BSA). It is hypothesized that both the ‘effective’ osmotic molecular weight, A e , and the solute/solvent interaction parameter, I, in the empirical relation M solvent M solute = ( RTϱ A e ) 1 gp + I [1] can be used as measures of protein folding. I is a measure of solvent perturbed by the solute and is thought to depend directly upon the solvent accessible surface area (ASA). It is reasoned that larger solvent accessible surface area of an unfolded or denatured protein should perturb more water and produce larger I-values. Thus I-values allow calculation of a unfolded protein fraction, f u a , due to changes in relative solvent accessible surface area. It has been observed that A e decreases for filamentous, denatured proteins due to segmental motion of the molecule [2]. This allows calculation of unfolded protein fraction from the effective molecular weight, f u m . Colloid osmotic pressure of BSA was measured in a range of salt concentrations at 25°C, and pH = 7 (above the isoelectric point of BSA at pH = 5.4). Both S and I were used to monitor protein folding as the salt concentration was varied. In general, larger and variable I-values and smaller A e were observed at salt concentrations less than 50 mmolal NaCl ( I max = 8.9), while constant I = 4.1 and A e = 66,500 were observed above 50 mmolal NaCl. The two expressions for fractional unfolding ( f u a and f u m ) are in general agreement. Small differences in the parameters below 50 mmolal salt concentration are explained with well known shifts in the relative amounts of α-helix, β-sheet and random coil in denatured BSA. The relative amounts of these shifts agree with predictions in the literature attributed to continuous BSA expansion rather than an ‘all-or-none’ conversion.

Indirect estimation of filtration variables in rat lungs calculated by protein concentration or osmotic pressure method.

We reported a new way for estimating filtration variables: K(filtration coefficient), Ppmv (perimicrovascular pressure) and sigma (protein reflection coefficient), from 3 different measurements of weight gain at two protein concentrations of perfusate (Cmv) and at two vascular pressures (Pvasc). We used the Starling equation for calculating those variables using two different formulas which expressed that all protein moves by convection. In this report, we compared those two formulas: 1) 1--sigma = pi pmv/pi mv, which is already reported (Tanita et al. 1990), and 2) 1--sigma = Cpmv/Cmv. We measured filtration rate (Q) by a gravimetric method in isolated rat lung lobes in zone 1 conditions (alveolar pressure = 20 cmH2O) at two vascular pressures, Pvasc = 15 or 8 cmH2O and perfused the lobes with plasma containing a low or a high concentration of protein. By extrapolating the log of the rate of weight gain to t = 0, we obtain the initial filtration rate. Cmv was measured and pi mv was estimated by Yamada's equation (Yamada et al. 1985). The reflection coefficient calculated in 1--sigma = pi pmv/pi mv method is computed 10% higher than that in 1--sigma = Cpmv/Cmv method. However, the filtration coefficient or the perimicrovascular pressure calculated in either method was identical. We conclude that filtration variables can be estimated easily by pi method and those variables are comparable to those estimated by C method which are theoretically more acculate but more complicated in calculation.

Mass transfer coefficients in cross-flow ultrafiltration

Usually, in concentration polarization models, the mass transfer coefficient is an unknown parameter. Also, its variation with changing experimental circumstances is in question. In the literature, many relationships can be found to describe the mass transfer coefficient under various conditions, as well as various corrections for deviating behaviour during ultrafiltration. To obtain reliable mass transfer coefficient relations directly from experimental data, two methods were tested: a method using the osmotic pressure difference during an ultrafiltration experiment, and a method based on the variation in observed retention when cross-flow velocities are changed. The osmotic pressure method appeared to be too insensitive for changing experimental circumstances (according to theoretical considerations). The velocity variation method appeared to be much more useful, although the error in the mass transfer coefficients obtained can be rather large owing to experimental and fitting uncertainties. Therefore the traditional mass transfer relations used in ultrafiltration may be as reliable as (and much more easy to use then) the velocity variation method. The velocity variation method can probably still be used in practice, however, when one or more of the parameters needed in the conventional mass transfer coefficient relations is unknown.

Serum transferrin of a reptile, the anaconda, Eunectes marinus

1. 1. Serum transferrin of the anaconda, Eunectes marinus, isolated by means of ionexchange chromatography, gel filtration, and starch-block electrophoresis, lacked sialic acid in contrast to the mammalian and avian serum transferrins. 2. 2. Ultracentrifugal analysis indicated a S 20w 0 of 4.73–4.86 and equilibrium molecular weight of 69,900–75,200. 3. 3. Sedimentation viscosity methods produced a molecular weight of 68,700 and an osmotic pressure method yielded a value of 75,600. 4. 4. Spectrophotometric titration indicated 1.648 μg. of ferric iron bound per mg. of protein, or molecular weight of 68,000 if a moles of iron are bound per mole of transferrin.

Simple construction to determine protein molecular weights by the osmotic pressure method.

This short note presents a simple device to determine protein molecular weights through osmotic pressure.

The molecular weight distribution of polypropylene

AbstractThe Gel Permeation Chromatograph has been used for obtaining values of weight‐average and number‐average molecular sizes Aw and An and the heterogeneity indices Aw/An for a series of polypropylenes. Absolute values of Mw and Mn, the weight‐average and number‐average molecular weights, have also been obtained from the same samples with light‐scattering and osmotic pressure methods. Comparisons of the data from the gel permeation chromatograph with the data from the absolute measurements have been used for calculating Q, the constant used for converting Aw and An to the corresponding Mw and Mn values. Other correlations of interest, such as intrinsic viscosity versus weight‐average molecular weight and melt flow, and Newtonian viscosity versus weight‐average molecular weight, are also given.

Structure of the Tobacco Mosaic Virus Particle; Polymerization of Tobacco

The chapter describes a critical analysis of the molecular weight of tobacco mosaic virus (TMV) and with polymerization of TMV protein. TMV has a very high molecular weight and measurements of double refraction of flow led to the conclusion that the particles are rod-shaped. The molecular weight of TMV has been determined adequately by physicochemical methods and measurements with the electron microscope. These yielded with fair uniformity a value close to 40 million. A value of about 23 Å for the pitch of the helix of the virus was determined from X-ray diffraction measurements, and pertains to the virus in wet gels. In the determination of molecular weight with the electron microscope, it is desirable to utilize a technique that does not depend upon the retention of the wet particle dimensions. Some of the earliest determinations of molecular weight were done by sedimentation and diffusion. Molecular weights obtained by this method do not depend on assumptions about the molecular configuration. Light scattering has been used extensively for the determination of particle weight. The method is particularly useful because of its sensitivity over a wide range of particle sizes and its ability to provide information on particle shape. Subsequent studies have established the correctness of the assumption that water is released upon polymerization. TMV, a protein seems to be a trimer of the chemical subunit. Its polymerization has been studied primarily by light scattering and osmotic pressure methods. Within certain limits, the polymerization can be interpreted quite accurately in terms of the mathematics of condensation polymerization. Accompanying the release of water molecules upon polymerization is an increase in partial specific volume. Hydrogen ions are bound during polymerization.

Viscosity–molecular weight relationship for polyvinyl acetate

AbstractThe relationship between limiting viscosity number and molecular weight of PVAc was determined and compared with the results by several authors. Samples of lowconversion PVAc were used. The weight‐average molecular weights were determined by a light‐scattering method and the number‐average molecular weights by endgroup determinations and the osmotic pressure method. From those experiments, it was proved that the ratio M̄w/M̄n for low conversion PVAc is equal to 2, as expected by theory. The relationships obtained are the following: [η] = 1.02 × 10−2 Mw0.72 (in acetone); [η] = 1.07 × 10−2 Mw0.71 (in MEK); [η] = 3.14 × 10−2 Mw0.6 (in methanol); and [η] = 9.20 × 10−2Mw0.5 (in a ⊖ solvent)where [η] is expressed in milliliters per gram and a mixture of methyl isopropyl ketone (72.7 vol‐%)and n‐heptane (27.3 vol.‐%)was chosen as the ⊖ solvent. These relationships were converted to relationships for perfectly homogeneous fractions. The relationship in acetone, [η] = 1.08 × 10−2 M0.72, was compared with literature data after the latter were converted to data corresponding to perfectly homogeneous fractions in acetone at 30°C., and was found to be in good agreement. Mean‐square radii of gyration, 〈S2〉, and second virial coefficients, A2, of PVAc were also determined in the acetone and methyl ethyl ketone solutions and the results compared with literature values.

Osmotic Electric or Magnetic Field

The usual osmotic pressure method for the determination of molecular weights becomes inaccurate when applied to solutes with high molecular weights because the solvent chemical potential is too sensitive to pressure changes. Since the solvent chemical potential is much less sensitive to changes in electric or magnetic field, the suggestion is made that these variables might be useful in osmotic experiments. A few schematic arrangements and a numerical example are discussed. Any possible advantage of the proposed method, over the conventional osmotic pressure method, rests on the replacement of a measurement of a small pressure difference by the measurement of a sizable electric or magnetic field coupled with a null observation on the pressure difference.

Infrared spectroscopy of polyethylene terephthalate

AbstractThe absorption spectra of polyethylene terephthalate, polyethylene‐D4 terephthalate and polyethylene terephthalate‐D4 were investigated. From these spectra and those of other known compounds, assignments were made for most of the bands in the 2 to 15 micron region. The 13.7 μ band was shown to be due to the out‐of‐plane bending of the aromatic hydrogen. The bands in this region known to vary in intensity with crystalline/amorphous ratio of the polymer were shown to be present in the spectrum of ethylene dibenzoate and to behave in an analogous manner with changes of state. From a study of this model compound and other considerations, rotational isomerism was postulated as the origin of the variation in intensity of these bands. Carboxyl and hydroxyl endgroup bands were identified and used to determine polymer number‐average molecular weight in good agreement with values obtained by osmotic pressure methods. A band arising from ether linkages (which are formed via dehydration during polymer synthesis) was identified.

Molecular weight‐intrinsic viscosity relationship and molecular weight distribution of low pressure polyethylenes

AbstractMolecular weights of low pressure polyethylene fractions were measured by an ebulliometric method and an osmotic pressure method. The results can be correlated by an equation, [η] = 5.10 × 10−4 M0.725, with the intrinsic viscosity measured at 130°C. in Tetralin, for a molecular weight greater than 3750. All three types of polymer fractions, Ziegler‐type low pressure polyethylene, Phillips low pressure polyethylene, and polymethylene from the decomposition of diazomethane, conform to the above correlation. The molecular weight distributions of two samples of Ziegler type polyethylene and one sample of Phillips' Marlex 50 were determined. All three distributions were found to be very broad and contained large amounts of low molecular weight materials.

The Nature of the Hemicelluloses of Jute Fiber

Hemicellulose I from jute fiber has been subjected to periodate oxidation under different conditions. From the amount of formic acid liberated during the oxidation under optimum conditions and from its nonreducing character, it is suggested that hemicellulose I has a branched structure. Its molecular weight by the osmotic-pressure method has been found to be about 20,000. Methylaldobiuronic acid, derived from hemicellulose I, gives both formic acid (2 mols.) and formaldehyde (1 mol.) on oxidation with periodate. It appears to be 3- (3-methylglucuronosyl )- D-xylose. Based on the observations made here, a provisional structure is suggested for hemicellulose I.

Molecular Weight of Native Cellulose

THE molecular weight of cellulose is of great interest to cellulose chemistry, and many attempts have been made to determine it. The cellulose derivatives, esters and ethers, can in general be dissolved in simple organic solvents, and their molecular weights determined by the osmotic pressure method. It is questionable, however, if the derivatives can be prepared without degradation of the cellulose molecule. Therefore the study of cellulose in cuprammonium solutions is of very great interest. It has never been possible to carry out osmotic measurements of these solutions, owing to their high vapour pressure and the difficulties of membrane materials. Staudinger1 has extrapolated his ‘viscosity rule’ from measurements of relatively low molecular weight materials and obtained degrees of polymerization of 2,000–3,000 for native cotton and ramie. Sedimentation equilibrium measurements were performed by Kraemer2, who obtained values up to 1,300 for purified cotton linters, and estimated the molecular weight of native cellulose to be at least 570,000 (D.P. 3,500). Later, Mosimann3 showed that sedimentation equilibrium experiments with filament molecules (nitrocelluloses) of very high molecular weights give doubtful results owing to swelling-pressure effects.