Adaptive Synthesis of Functional Amphiphilic Dendrons as a Novel Approach to Artificial Supramolecular Objects

Supramolecular structures, such as micelles, liposomes, polymerosomes or dendrimerosomes, are widely studied and used as drug delivery systems. The behavior of amphiphilic building blocks strongly depends on their spatial distribution and shape of polar and nonpolar component. This report is focused on the development of new versatile synthetic protocols for amphiphilic carbosilane dendrons (amp-CS-DDNs) capable of self-assembly to regular micelles and other supramolecular objects. The presented strategy enables the fine modification of amphiphilic structure in several ways and also enables the facile connection of a desired functionality. DLS experiments demonstrated correlations between structural parameters of amp-CS-DDNs and the size of formed nanoparticles. For detailed information about the organization and spatial distribution of amp-CS-DDNs assemblies, computer simulation models were studied by using molecular dynamics in explicit water.     

Novel semi-interpenetrating network hydrogels based on monosaccharide oligomers with itaconic moiety: synthesis and properties

Hydrogel-based drug delivery systems encounter great scientific attention nowadays. Semi-interpenetrating network systems with hydrogel features have been studied as potential drug carriers due to their water intake capacity, biocompatibility and biodegradability. One of the most important features of drug delivery systems is biocompatibility and as such materials derived from natural resources seem to be more appropriate to act as excipients. In this respect, two new semi-interpenetrating networks (semi-IPNs) with hydrogel features based on chitosan, two novel oligomers derived from monosaccharides and 2-hydroxyethylmethacrylate (HEMA) have been synthesized and characterized using FTIR, thermogravimetry, SEM/EDX and swelling behavior. The new sugar-derived oligomers (GI and MI) with double bonds available for further polymerization were obtained by polycondensation of 1,3-propanediol with dicarboxylic acids derived from glucose/mannose skeleton with itaconic anhydride moieties. GI and MI oligomers were characterized by FTIR, NMR spectroscopy and ESI–MS spectrometry, which showed molecular weights of about 7000 Da and linear polymerization chain structure. The new semi-IPNs show good thermal behavior and these hydrogels display a swelling tendency by loading significantly more water in an acid environment than in a neutral solution. Moreover, these superabsorbent hydrogels are able to load significant amount of hydrosoluble active principle (herein the antibiotic levofloxacin) and their releasing profile is marked by an important “burst effect”.     

Molecular Dimensions and Porous Structure of Activated Carbons for Sorption of Xylene and Isooctane

The sorption of xylene and isooctane was measured by the gravimetric flow sorption method on commercial activated carbons (ACs), namely, virgin and reactivated ACs. Nitrogen physisorption, high‐pressure mercury porosimetry, helium pycnometry, iodine number, pH measurement, Raman and X‐ray photoelectron spectroscopies were applied for textural, structural, and surface characterization of ACs. The equilibrium geometries of isooctane and xylene molecules were modeled using density functional theory (DFT) calculations. Their dimensions were estimated to be correlated with textural properties of ACs to reveal the effect of size selectivity. The key factors influencing the adsorption capacity of the chosen ACs for both tested volatile organic compounds (VOCs) were found to be the mesopore surface area and the surface basicity.     

Active vibration control of a fluid/plate system using a pole placement controller

We consider the problem of active reduction of the structural vibrations induced by the sloshing of large masses of fuel inside a partly full tank. The proposed study focuses on an experimental device mimicking an aircraft wing made of an aluminium rectangular plate equipped with piezoelectric patches at the clamped end and with a cylindrical tip tank, more or less filled with liquid. After deriving a representative finite-dimensional model of the complete system, containing the first five structural modes of the plate and the first three liquid sloshing modes, a controller is computed. Since our main scope is to control the most energetic mode of the structure, a full state-feedback method coupled with an observer is used. Finally, the controller is also tested for different initial conditions/perturbations and the results are compared with the ones obtained with an H _∞ controller. Experimental results illustrate the relevance of the chosen strategy.     

Robust control of a bimorph mirror for adaptive optics systems

We apply robust control techniques to an adaptive optics system including a dynamic model of the deformable mirror. The dynamic model of the mirror is a modification of the usual plate equation. We propose also a state-space approach to model the turbulent phase. A continuous time control of our model is suggested, taking into account the frequential behavior of the turbulent phase. An H(infinity) controller is designed in an infinite-dimensional setting. Because of the multivariable nature of the control problem involved in adaptive optics systems, a significant improvement is obtained with respect to traditional single input-single output methods.     

Accumulation of organic carbon over the past 150 years in five freshwater peatlands in western and central Europe

Under predicted scenarios of global climate change, peatlands may become a net source of greenhouse gases which will accelerate warming of the atmosphere. Comparative studies of peat bogs along present climatic gradients may provide an insight into the future response of boreal and subarctic peatlands to changing temperature and moisture. Three maritime peat bogs in the British Isles, and two high-elevation peatlands in the Czech Republic were studied. All sites were relatively wet, the mean annual temperatures were higher by up to 6 degrees C at the British/Irish sites than at the Czech sites. Cumulative carbon content in (210)Pb-dated Sphagnum-dominated vertical peat cores increased from the warmer to the colder sites when evaluated for the most recent decades (since ca. 1950). That would correspond to formation of thinner, more highly decomposed peat deposits over the long-term in warmer conditions, and deeper peat bogs in colder conditions. However, when cumulative carbon content was evaluated for the last ca. 150 years, no relationship was found between mean annual temperature and the carbon pool size. Even along broad present-day climatic gradients, site-specific factors controlled organic carbon preservation in peat. Pollen analysis was instrumental in corroborating the (210)Pb dates, identifying wet and dry periods in the past, and it also provided evidence for increasing nitrogen loads in wetland areas.     

Characterization of sewage plant hydrocolloids using asymmetrical flow field-flow fractionation and ICP-mass spectrometry

Asymmetrical flow field-flow fractionation (AF⁴) was applied to characterize aquatic colloids from biological sewage plants and to infer information of colloidal loads, sources, and sinks within the plants, resp. the colloidal interaction with the aqueous phase and the sewage sludge. To characterize the colloids further, especially the distributions of colloid associated heavy metals, the AF⁴ system was coupled to an inductively coupled plasma mass spectrometer (ICP-MS). The size distribution is determined by AF⁴ with UV absorbance and fluorescence detection after a calibration by monodisperse polystyrene sulfonate standards (PSS). Samples from different sewage plants and from different depths and locations within a plant were compared. The fulvic/humic acid fraction with a particle diameter d_p<10 nm appeared to be comparable in all samples and decreases only slightly along the plants, whereas larger colloids with d_p>10 nm almost completely passed into the sewage sludge. The concentrations of the initial colloidal heavy metals decreased along the plants.     

Valve interstitial cell culture: Production of mature type I collagen and precise detection

Collagen often acts as an extracellular and intracellular marker for in vitro experiments, and its quality defines tissue constructs. To validate collagen detection techniques, cardiac valve interstitial cells were isolated from pigs and cultured under two different conditions; with and without ascorbic acid. The culture with ascorbic acid reached higher cell growth and collagen deposition, although the expression levels of collagen gene stayed similar to the culture without ascorbic acid. The fluorescent microscopy was positive for collagen fibers in both the cultures. Visualization of only extracellular collagen returned a higher correlation coefficient when comparing the immunolabeling and second harmonic generation microscopy images in the culture with ascorbic acid. Lastly, it was proved that the hydroxyproline strongly contributes to the second‐order susceptibility tensor of collagen molecules, and therefore the second harmonic generation signal is impaired in the culture without ascorbic acid.     

Osteoarthritic process modifies expression response to NiTi alloy presence

Nickel-titanium alloy (nitinol, NiTi) is a biomaterial with unique thermal shape memory, superelasticity and high damping properties. Therefore NiTi has been used in medical applications. In this in vitro study, the effect of NiTi alloy (with two surface modifications – helium and hydrogen) on gene expression profile of selected interleukins (IL-1β, IL-6 and IL-8) and matrix metalloproteinases (MMP-1 and MMP-2) in human physiological osteoblasts and human osteoarthritic osteoblasts was examined to respond to a question of the different behavior of bone tissue in the implantation of metallic materials in the presence of cells affected by the osteoarthritic process. The cells were cultivated in contact with NiTi and with or without LPS (bacterial lipolysaccharide). Changes in expression of target genes were calculated by 2^-ΔΔCt method. An increased gene expression of IL-1β in osteoarthritic osteoblasts, with even higher expression in cells collected directly from the metal surface was observed. In case of physiological osteoblasts, the change in expression was detected after LPS treatment in cells surrounding the disc. Higher expression levels of IL-8 were observed in osteoarthritic osteoblasts after NiTi treatment in contact with alloy, and in physiological osteoblasts without relation to location in combination of NiTi and LPS. IL-6 was slightly increased in physiological osteoblastes after application of LPS. MMP-1 expression level was obviously significantly higher in osteoarthritic osteoblasts with differences regarding the metal surface and location. MMP-2 expression was decreased in both cell lines after LPS treatment. In conclusion, results of present study show that the NiTi alloy and the treatment by LPS, especially repeated doses of LPS, change the gene expression of selected ILs and MMPs in human osteoblast cell cultures. Some of the changes were depicted solely to osteoarthritic osteoblasts.     

The use of liposomes in the modification of polycaprolactone fibers

Polycaprolactone is fully bioresorbable and biocompatible material. Liposomes containing nanocopper, nanosilver, and nanogold are known to have antifungal and antibacterial properties and to further aid in the synthesis of collagen and elastin in the skin. It is possible to combine the properties of polycaprolactone fibers and liposomes in new approaches to deliver active substances through cosmetics and medicines. The aim of the research was to examine the possibility of simple modification of PCL fibers with use of nanocopper, nanogold, and nanosilver incorporated liposomes. The size and the type of the liposomes were examined using optical microscopy and DLS techniques. The fibres modified with liposomes were investigated using SEM and FTIR techniques. Additionally the contact angle measurements were performed. The study shows an innovative method of modifying polycaprolactone nonwoven textiles. This combination of PCL fibers and liposomes allows easy and efficient preparation and delivery of active substances to a particular location. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43299.