Influence of an antimicrobial treatment on the strength properties of polyamide/elastane weft‐knitted fabric

Polyamide/elastane weft‐knitted fabric, as a suitable compression material, was treated with gentamicin sulfate and a natural antimicrobial preparation of the autochthonous essential oil of Picea abies. The antimicrobial bioactivity of the treated fabric in vitro was tested for different groups of bacteria and a fungus (Staphylococcus aureus, Escherichia coli, Klabsiella, and Candida albicans). The results of the experiment showed that the antimicrobial‐treated knitted fabric expressed a wide range of bactericidal, fungicidal, and bacteriostatic activity versus the various groups of microorganisms. The influence of the antimicrobial treatments on the tensile strength and elongation, tear strength and elongation, stiffness, and elasticity of the chosen test material was also examined. These properties of the fabric were changed after the antimicrobial treatments. Both the tensile strength and tear strength increased about 14% after the treatment. The scope of the experiment also included the testing of the compression distribution at the skin/knitted fabric interface on the legs of human test subjects. Pressure generated by the application of the knitted fabric on the leg surface increased in correlation with a decrease in the leg circumference. On the basis of these observations, it was concluded that the knitted fabric could be used as a compression textile before and after the treatment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4012–4019, 2007     

Statistical design of experiments of acid activation of smectite clay from Serbia and its bleaching capacity

BACKGROUND: Serbian smectite clay has been activated using a response surface method with central composite design. Because, among the criteria of an edible oil, colour is the most important factor in the commercial value of the oil, and since the colour is due to the presence of pigments such as β‐carotene in the crude oil, acid‐activated clay was used for decolourisation of soybean oil. RESULTS: The effects of five parameters, namely, temperature, time, acid strength, solid/liquid ratio and stirring speed, on the process of acid activation of the clay and its bleaching capacity were determined using a statistical model. The results indicated that all parameters were significant factors in the bleaching capacity of acid‐activated clay, and a quadratic polynomial equation for bleaching capacity was obtained by multiple regression analysis. The optimal bleaching capacity was estimated to be 96.61% for an experimental run under the following conditions: activation temperature 80 °C, HCl concentration 4.78 mol L^?1, stirring speed 450 rpm, solid/liquid ratio 1:4.5 and activation time 2.81 h. CONCLUSIONS: The central composite design, regression analysis and response surface method were effective in identifying the optimal conditions for bleaching capacity of acid‐activated smectite. Copyright © 2008 Society of Chemical Industry     

The influence of structural properties on the dye diffusion and dyeabilty of PA 6 fibres

The relationships were investigated between the structural and dyeing properties of different structurally modified PA 6 fibers. PA 6 monofilament yarn samples were applied having different crystalline degrees and different content of alpha, respectively gamma crystalline modification. The diffusion coefficients of two different acid dyes were determined together with the content of dyestuff absorbed (under specific conditions) by fiber samples. In order to estimate colorimetry method from the viewpoint of polymer structural change detection, the colors of the dyed PA 6 samples were determined (L*, a*, b*, C*, h coordinates) and the color differences (L*, a*, b*, C*, H*, E*) were calculated between untreated standard and structurally modified samples. The dyeability of PA 6 fibers depended mainly on the way in which crystallinity had been achieved, i.e. on the material's history. Different crystalline modifications caused different sorption properties and fiber dyeability. Smaller increases (app 20%) of crystallinity degree caused a decrease in diffusion coefficients. Contrary to expectations, the significant increase of crystallinity degree (app 50%) had an influence on the increase of dyeability, presumably owing to the formation of larger empty spaces in the structure. The results achieved by colorimetry were in good correlation with dye absorption measurements. The colorimetry of dyed fiber samples was sensitive enough to detect even small differences in the quantities of absorbed dyestuff.     

Biology of TiO2-oligonucleotide nanocomposites

Emerging areas of nanotechnology hold the promise of overcoming the limitations of existing technologies for intracellular manipulation. These new developments provide approaches for the creation of chemical-biological hybrid nanocomposites that can be introduced into cells and subsequently used to initiate intracellular processes or biochemical reactions. Such nanocomposites would advance medical biotechnology, just as they are improving microarray technology and imaging in biology and medicine, and introducing new possibilities in chemistry and material sciences. Here we describe the behaviour of 45-A nanoparticles of titanium dioxide semiconductor combined with oligonucleotide DNA into nanocomposites in vivo and in vitro. These nanocomposites not only retain the intrinsic photocatalytic capacity of TiO2 and the bioactivity of the oligonucleotide DNA (covalently attached to the TiO2 nanoparticle), but also possess the chemically and biologically unique new property of a light-inducible nucleic acid endonuclease, which could become a new tool for gene therapy.     

An approach to pseudo-integration of set-valued functions

The set-valued function in general is an important mathematical notion that plays a crucial role in several practical areas. This paper does not focus only on the pseudo-integration of set-valued functions in general, but also on a special case, namely on the pseudo-integration of interval-valued functions. Therefore, an approach to the integration of set (interval)-valued functions based on both classical Aumann’s approach and pseudo-analysis’ tools is given. Also, some important properties of this type of integral are investigated.     

Durability of sulfur concrete in various aggressive environments

Durability of sulfur concrete with different fillers, as well as Portland cement concrete, was tested in the solutions of HCl, H₂SO₄, and NaCl. Regarding mass changes, in the solutions of HCl and H₂SO₄ sulfur concrete with talc and fly ash exhibited higher durability, while in NaCl samples with alumina and microsilica were better. The type of filler did not affect durability regarding compressive strength. Strength loss was higher in the solution of HCl comparing to H₂SO₄, while negligible in NaCl which is in accordance with apparent porosity increase. Portland cement concrete after two months lost 20% of mass.     

Functionalized multi-walled carbon nanotubes for oil spill cleanup from water

The growing global economy resulted in an incessant increase in transportation and exploitation of oil. Hence, the oil spillage has been considered a serious threat to aquatic and terrestrial ecosystems. Therefore, water purification has been considered a major challenge around the world. There are numerous classical methods available for oil removal from water, but owing to multiple defects and disadvantages, research efforts have focused to find such adsorbents which can improve oil adsorption capability. Traditional adsorbent material typically applied in oil removal includes activated carbon, organoclays, wool, zeolites, etc. These materials suffer from several drawbacks such as low absorption capacity, non-selective absorption, and complicated reusability, whereas nano-adsorbents offer multiple advantages such as having multiple sorption sites, large surface area, short intra-particle diffusion distance, tuneable pore size, and ease of low-temperature modification. Multi-walled carbon nanotubes (MWCNTs) are extensively used adsorbent materials with a strong affinity for the removal of organic pollutants. The functionalization MWCNTs further increase the sorption capacity of adsorbents manifolds to remove organic materials. These nanocomposites are also compatible with green materials and considered environmentally friendly adsorbents. This review paper aims at providing an insight to understand the properties of the MWCNTs and their potential use to adsorb hydrocarbons from water. Moreover, the synthesis methods of those materials, their modification procedures including the functionalization with metal oxide nanoparticles, and applications are also discussed in detail.

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Temporal sequence parameters in isodistributional surrogate data: model and exact expressions

In this paper, a set of formulae for the temporal spontaneous baroreceptor reflex (sBRR) sequence parameters in isodistributional (ID) surrogate data is derived. This is facilitated by representing successive positive or negative amplitude changes as a Markov chain model. The obtained analytical tool measures the effect of random fluctuations on the overall number of sequences, estimated from the original biomedical time series. The formulae are tested using ID surrogates of systolic blood pressure and pulse-interval signals recorded from 13 healthy male Wistar rats at baseline conditions.     

Time dependence of cellular chemical changes induced in prostate PC-3 cancer cells by two structurally related cardenolides monitored by Fourier transform infrared (FT-IR) spectroscopy

Human PC-3 prostate cancer cells were incubated in the presence of two cardenolides, i.e., ouabain and 19-hydroxy-2'-oxovoruscharin. Their effects were monitored by infrared spectroscopy of the cells after different exposure times to the cardenolides. Analysis of changes in absorbance intensities indicated that, for both compounds, the absorbance at one wavenumber with a minor contribution of a second wavenumber is sufficient to build a linear model accurate enough to assign more than 97% of the spectra to their correct time slot. Student t-tests and twodimensional correlation analysis (2D-COS) indicated that both drugs have very similar effects on PC-3 cells. However, asynchronous 2D maps revealed significant differences and allowed the sequence of the spectral changes to be determined: 1395 → 1695 cm(-1) for ouabain, and 1400 → 1655 → 1100 → 1250 → 1020 cm(-1) for 19-hydroxy-2'-oxovoruscharin. 2D correlation map subtraction allowed the identification of very specific differences in the impact of both compounds on PC-3 cells, in particular the ability of 19-hydroxy-2'-oxovoruscharin to affect nucleic acid of PC-3 cells.