41 research outputs found
Investigations of copper(II) complexation by fragments of the FBP28 protein using isothermal titration (ITC) and differential scanning calorimetry (DSC)
A Study of the Influence of Charged Residues on β-Hairpin Formation by Nuclear Magnetic Resonance and Molecular Dynamics
Characterization and cytotoxic effect of aqua-(2,2′,2′′-nitrilotriacetato)-oxo-vanadium salts on human osteosarcoma cells
Possibilities of using fruit skins in quince snack technology®
W artykule przedstawiono możliwości wykorzystania odpadu,
jakimi są skórki pigwowca japońskiego, w celu wytworzenia
przekąsek. Wykonano badania dotyczące zmian aktywności
wody, masy i barwy przy zastosowaniu różnych metod suszenia,
poprzedzonych odwadnianiem osmotycznym. Przeprowadzono
również ocenę sensoryczną, którą przyjęto za wskaźnik
atrakcyjności oraz jakości produktu. Wykazano, że rodzaj roztworu
osmotycznego wpływa na barwę oraz smak końcowego
produktu, zaś metoda suszenia wpływa na aktywność wody,
twardość i wygląd zewnętrzny produktu. Poniższy artykuł stanowi
praktyczne podejście dotyczące wykorzystania skórek
jako pozostałości w procesie przetwarzania owoców w celu
wytworzenia wartościowego produktu.The article presents the possibilities of using the waste as Japanese
quince skins for the production of snacks. Changes in
water activity, mass, colour using various drying methods preceded
by osmotic dehydration were made in this study. A sensory
evaluation was also carried out, which was adopted as
an indicator of the attractiveness and quality of the product.
The type of osmotic solution affects the colour and taste of
the final product, while the method of drying affects the water
activity, hardness and external appearance of the product. The
following article is a practical approach regarding the use of
skins as residues in the fruit processing process to produce a
valuable product
On the Effect of pH, Temperature, and Surfactant Structure on Bovine Serum Albumin–Cationic/Anionic/Nonionic Surfactants Interactions in Cacodylate Buffer–Fluorescence Quenching Studies Supported by UV Spectrophotometry and CD Spectroscopy
Due to the fact that surfactant molecules are known to alter the structure (and consequently the function) of a protein, protein–surfactant interactions are very important in the biological, pharmaceutical, and cosmetic industries. Although there are numerous studies on the interactions of albumins with surfactants, the investigations are often performed at fixed environmental conditions and limited to separate surface-active agents and consequently do not present an appropriate comparison between their different types and structures. In the present paper, the interactions between selected cationic, anionic, and nonionic surfactants, namely hexadecylpyridinium chloride (CPC), hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene glycol sorbitan monolaurate, monopalmitate, and monooleate (TWEEN 20, TWEEN 40, and TWEEN 80, respectively) with bovine serum albumin (BSA) were studied qualitatively and quantitatively in an aqueous solution (10 mM cacodylate buffer; pH 5.0 and 7.0) by steady-state fluorescence spectroscopy supported by UV spectrophotometry and CD spectroscopy. Since in the case of all studied systems, the fluorescence intensity of BSA decreased regularly and significantly under the action of the surfactants added, the fluorescence quenching mechanism was analyzed thoroughly with the use of the Stern–Volmer equation (and its modification) and attributed to the formation of BSA–surfactant complexes. The binding efficiency and mode of interactions were evaluated among others by the determination, comparison, and discussion of the values of binding (association) constants of the newly formed complexes and the corresponding thermodynamic parameters (ΔG, ΔH, ΔS). Furthermore, the influence of the structure of the chosen surfactants (charge of hydrophilic head and length of hydrophobic chain) as well as different environmental conditions (pH, temperature) on the binding mode and the strength of the interaction has been investigated and elucidated
Modern applications of surface active agents
Surfactants have been known to mankind since the dawn of time. They have
been used primarily as washing and cleaning agents. However, today they are used
much more often in many fields of industry. This work focuses on two areas
of surfactants use, the agriculture and the food industry due to the direct
relationship between these two issues.
In agriculture, surfactants play a number of important roles. One of the
problems of modem agriculture is the low efficiency of spraying, associated with
the low absorption of liquid utility for plants. This problem is solved by surfactants,
as demonstrated by the example of glyphosate and the organosilicon compound
Silwet® L-77. Nowadays, substitutes for conventional surfactants are being sought.
Compounds produced by microorganisms are under great interest of scientists. It
has been shown that they are characterized by the lower toxicity as well as high
biodegradability, while maintaining the characteristics and properties of synthetic
compounds.
Directly related to the agriculture, the food industry also often uses surfactants.
In the production and processing of food surfactants play the role of such
compounds as emulsifiers, stabilizers, additives improving the texture of products
and increasing the durability of products. Sorbitan esters, e.g. sorbitan monolaurate,
their ethoxylated derivatives, e.g. Polysorbate 20, as well as sucrose esters, e.g.
sucrose monostearate, are readily used for this purpose. Great emphasis is placed on
the safety of compounds used in the food industry. As in the case of agriculture,
biosurfactants and compounds of natural origin are tested for use in the food
industry. Their use is not limited to being ingredients of products. They can play
a biocidal, as well as a protecting role against surface colonization by
microorganisms
Methods for determining critical micellar concentration of surfactants
Surface active agents, also known as surfactants, are a group of chemical
compounds that are used in various products of the chemical industry. These
compounds are components of medicines, detergents, motor oils and many others.
The multitude of uses of surfactants makes it important to know their aggregation
behaviour in solution. There are many methods used to analyse surfactants
behaviour in liquid phase. The choice of a particular technique usually depends on
the chemical structure of the surfactant.
An example of a method that is used in studies of ionic surfactants is
conductometry. This technique allows to study the dependence of specific
conductivity on surfactant concentration, enabling determination of critical micellar
concentration (CMC).
Capillary electrophoresis is another example of the method used to determine
the critical micellar concentration. It allows to make measurements in conditions
where other methods fail, including conductometric method. Surfactant solutions
differ in viscosity, which changes with the appearance of micelles in solution.
Measurement of marker compound migration time through surfactant solutions
of various concentrations allow to determine critical micellar concentration.
Isothermal titration calorimetry (ITC) allows to study the thermal effects
associated with the aggregation of surfactants into micelles. Based on the energy
changes that occur during titration, the critical micellar concentration of surfactant
can be precisely determined. ITC is very sensitive method, so basically it can be
used to examine all types of surfactants. In addition, the ITC method allows
to determine the thermodynamic parameters of the undergoing micellization
process.
The use of several measuring methods gives a more complete picture of the
phenomena occurring in solutions. It allows to understand aggregation process
more accurately. Therefore, CMC measurement are often made with the use
of several complementary methods