Microstructural analysis and magnetic characterization of native and magnetically modified montmorillonite and vermiculite

Two clay minerals of the similar 2 : 1 layer structure and chemical composition, vermiculite and montmorillonite, were studied using a wide spectrum of experimental methods in their original states and the magnetically modified states after mixing with microwave-synthesized iron oxide particles. This magnetic modification led to different microstructural morphology influencing magnetic behaviour at room and more pronounced at low temperatures.Web of Scienceart. no. 373810

Magnetically modified nanogold-biosilica composite as an effective catalyst for CO oxidation

The temperature-dependent biosynthesis of gold nanoparticles (AuNP) using diatom cells of Diadesmis gallica was successfully performed. The resulting biosynthesis product was a bio-nanocomposite containing AuNP (app. 20 nm) subsequently anchored on the silica surface of diatomaceous frustules. As-prepared nanogold-biosilica composite was tested as catalyst in the oxidation of carbon monoxide using gas chromatograph with thermal conductivity detector. For catalytic activity enhancement, bionanocomposite was magnetically modified by ferrofluid using two different methods, i.e., with and without the use of methanol. The oxidation of CO at 300 degrees C was 58-60% in the presence of nanogold-biosilica composites. CO conversion at 300 degrees C was only 15% over magnetically responsive sample modified in the presence of methanol. On the other hand, complete CO conversion was reached over direct (without methanol) magnetically modified nanogold-biosilica composite at 330 degrees C (GHSV = 60 l g(-1) h(-1)). Our results show, that the type of magnetic modification can influence the catalytic activity of bionanocomposite. The best catalytic effect in CO conversion established direct magnetically modified nanogold-biosilica composite.Web of Science1271158114

THE EFFECT OF EXOGENOUS PROTEASE IN BROILER DIETS ON THE APPARENT ILEAL DIGESTIBILITY OF AMINO ACIDS AND ON PROTEASE ACTIVITY IN JEJUNUM

Abstract The objective of this study was to evaluate the effect of a mono-component commercial serine protease supplement in broiler diets on apparent ileal amino acid digestibility and protease activity. A total of 150 male (28 d old) ROSS 308 were randomly placed into 30 battery pens and divided into 5 treatment groups with 6 replicates each. The experiment was performed for 7 days. Five dietary treatments were used: 2 standard protein diets without (SP) and with protease (SP + P) formulated 20.7 % CP, 2 lower-protein diets (19.9 % CP) without (LP) and with protease (LP + P) and one lower-protein diet with protease and with doubled rapeseed meal (RSM) content (SP-RSM + P) compared with the other treatments. Lower-protein diets were formulated with a 4 % decrease in the relative CP value compared with the standard protein diet. Enzyme protease was added to the diets at a concentration of 200 ppm (15,000 PROT units per kg). The diets contained 0.3 % Cr2O3 to facilitate the estimation of apparent AA digestibility and overall apparent ileal crude protein digestibility. Mono-component protease had no effect on apparent ileal AA digestibility or jejunum protease activity if diets contained the same level of RSM. The supplement of exogenous protease did not affect (P > 0.05) the apparent ileal AA digestibility coefficients if a higher RSM level was used. The CP level influenced (P < 0.05) only the coefficients of the apparent ileal AA digestibility of Pro and Arg. The RSM level (P < 0.01) had significant effects on protease activity in the jejunum

Multifunctional Electrospun Nanofibers Based on Biopolymer Blends and Magnetic Tubular Halloysite for Medical Applications

Tubular halloysite (HNT) is a naturally occurring aluminosilicate clay with a unique combination of natural availability, good biocompatibility, high mechanical strength, and functionality. This study explored the effects of magnetically responsive halloysite (MHNT) on the structure, morphology, chemical composition, and magnetic and mechanical properties of electrospun nanofibers based on polycaprolactone (PCL) and gelatine (Gel) blends. MHNT was prepared via a simple modification of HNT with a perchloric-acid-stabilized magnetic fluid–methanol mixture. PCL/Gel nanofibers containing 6, 9, and 12 wt.% HNT and MHNT were prepared via an electrospinning process, respecting the essential rules for medical applications. The structure and properties of the prepared nanofibers were studied using infrared spectroscopy (ATR-FTIR) and electron microscopy (SEM, STEM) along with energy-dispersive X-ray spectroscopy (EDX), magnetometry, and mechanical analysis. It was found that the incorporation of the studied concentrations of MHNT into PCL/Gel nanofibers led to soft magnetic biocompatible materials with a saturation magnetization of 0.67 emu/g and coercivity of 15 Oe for nanofibers with 12 wt.% MHNT. Moreover, by applying both HNT and MHNT, an improvement of the nanofibers structure was observed, together with strong reinforcing effects. The greatest improvement was observed for nanofibers containing 9 wt.% MHNT when increases in tensile strength reached more than two-fold and the elongation at break reached a five-fold improvement

Magnetické částice v biologických vědách

Magnetic nanoparticles represent an interesting material both present in various living organisms and usable for a variety of bio-applications. This review paper will summarise the information about biogenic magnetic nanoparticles, the ways used to synthesise biocompatible magnetic nanoparticles and complexes containing them, and the applications of magnetic nanoparticles in various areas of biosciences and biotechnologies