Motion of a massive microsphere bound to a spherical vesicle

We study the motion of a small solid particle (a few micrometers in size) attached to the membrane of a spherical giant lipid vesicle. By means of optical manipulation, the particle is first brought near the top of the vesicle, and released. We determine the friction experienced by the particle moving along the vesicle surface under the action of gravity. From experiments with latex and glass beads, we check that SOPC membranes are fluid at room temperature (static shear modulus u = 0) and estimate the shear viscosity of SOPC bilayers: nm = 3 * 10^(-6) surface poise

EFECT OF SMOKING ON THE ACCUMULATION OF POLYCYCLIC AROMATIC HIDROCARBONS, IN M. LONGISIMUS DORSI FROM PIGS AND POSSIBILITIES FOR REDUCING THEIR CONTENT

This study deals with the effect of smoking process and the accumulation of toxic polycyclic aromatic hydrocarbons in Musculus Longissimus dorsi from pigs and studies the possibilities to reduce their content. The studies were conducted on two samples boiled-smoked fillet – one salted with brine and added proteincoating, whereas the second one salted with brine and added ascorbic acid.Qualitative identification and quantification of polycyclic aromatic hydrocarbons is done by gas hromotograph Hewlett Packard 5890 with LG 85 B spectrophotometric detector. It was found that the use of proteincoatings, significantly reduces the amount of polycyclic aromatic hydrocarbons in the smoking of Musculus Longissimus dorsi from pigs. The addition of ascorbic acid in conjunction with protein salting coatings technology represents a significant option for reducing the content of the benzo(a)pyrene , which contributes to the safety in the final products. In studies of the samples of proteins and ascorbic acid, the inner layers i.e the muscle tissue was found to contain significantly less amount of benzo(a)pyrene (1,75 ± 0,06 μ/kg) compared with the values found in the surface layers (2,31 ± 0,02 μg/kg)

Motion of a massive particle attached to a spherical interface: statistical properties of the particle path

We have studied the motion of a Brownian particle on a spherical interface under gravity, with the aim of setting up a protocol to measure the friction (f) felt by such a particle in experimental conditions. Our analysis is based on the Schmoluchowski equation for particle motion. Essentially we derive a practical criterion to find f from the average particle path. Our statements are illustrated by a few experimental and numerical examples. Numerical paths are obtained by computer simulation and experimental paths are those of micrometre-sized latex or glass particles attached to spherical giant lipid (SOPC) vesicles. From experimental values of f, we estimate the surface shear viscosity of SOPC bilayers to be in the range 3-8×10^(-6) Poise

Analytical modeling of micelle growth. 3. Electrostatic free energy of ionic wormlike micelles -- effects of activity coefficients and spatially confined electric double layers

Hypotheses: To correctly predict the aggregation number and size of wormlike micelles from ionic surfactants, the molecular-thermodynamic theory has to calculate the free energy per molecule in the micelle with accuracy better than 0.01 kT, which is a serious challenge. The problem could be solved if the effects of mutual confinement of micelle counterion atmospheres, as well as the effects of counterion binding, surface curvature and ionic interactions in the electric double layer (EDL), are accurately described. Theory: The electric field is calculated using an appropriate cell model, which takes into account the aforementioned effects. Expressions for the activity coefficients have been used, which vary across the EDL and describe the electrostatic, hard sphere, and specific interactions between the ions. New approach for fast numerical calculation of the electrostatic free energy is developed. Findings: The numerical results demonstrate the variation of quantities characterizing the EDL of cylindrical and spherical micelles with the rise of electrolyte concentration. The effect of activity coefficients leads to higher values of the free energy per surfactant molecule in the micelle as compared with the case of neglected ionic interactions. The results are essential for the correct prediction of the size of wormlike micelles from ionic surfactants. This study can be extended to mixed micelles of ionic and nonionic surfactants for interpretation of the observed synergistic effects.Comment: 36 pages, 6 figures, Supplementary Information: 12 pages, 1 figur

Optical microrheology using rotating laser-trapped particles

We demonstrate an optical system that can apply and accurately measure the torque exerted by the trapping beam on a rotating birefringent probe particle. This allows the viscosity and surface effects within liquid media to be measured quantitatively on a micron-size scale using a trapped rotating spherical probe particle. We use the system to measure the viscosity inside a prototype cellular structure.Comment: 5 pages, 4 figures. v2: bibliographic details, minor text correction

Funkcionalne osobine sojeva bakterija mlečne kiseline i mikrokoka u sredini sličnoj mesnoj masi sirovih kobasica kao modelu

In this study we investigated the potential probiotic properties of Lactobacillus plantarum L 24 - 2, Lactococcus lactis biovar diacetylactis N 237 and strain Micrococcus sp. It has been found that microbial species exhibited the ability to survive under conditions of high concentrations of bile salts (2.0%) and low pH (2.0). This ability varies for different types, but they will remain until the end of experiments zivotosposobne. This, together with the antimicrobial activity projavljenoj them makes them suitable for the new composition uklucivane the starter culture, which can be effectively used as an antimicrobial barrier to the development of pathogenic bacteria in the manufacture of a crude - product of dried meat.U ovom radu su ispitivana potencijalna probiotska svojstva bakterija Lactobacillus Plantarum soj L 24 - 2, Lactococcus lactis biovar diacetilactis soj N 237 i Micrococcus sp. Utvrđeno je da mikrobne vrste pokazuju sposobnost za preživljavanje pod uslovima visoke koncentracije žučnih soli (2,0%) i niskog pH (2.0). Ova sposobnost varira kod različitih ispitivanih bakterija, ali sve one ostaju životno sposobne do kraja eksperimenata. Ovo, zajedno sa dokazanom antimikrobnom aktivnošću čini ih pogodnim za uključivane u sastav novih starter kultura, koje mogu efikasno poslužiti kao antimikrobna barijera za razvoj patogenih bakterija u proizvodnji sirovih - sušenih proizvoda od mesa