172 research outputs found
Polymer acrylic hydrogels with protein filler: Synthesis and characterization
ArticleThe water-retention hydrogel composites were synthesized by the free-radical
polymerization depending on the order of addition filler of the protein hydrolysate. As the filler
was used protein hydrolysate, ‘Biostim’, obtained by processing cattle hides. The influence of
gelation time on the synthesis parameters of hydrogel compositions was investigated. It is found
that the gelation time of the sample without filler is 2–2.5 times longer than filled of hydrogel
compositions. The structural characteristics of polymer composition by TGA, DSC and atomic
force microscopy were determined. FTIR spectra found decrease in the intensity of vibrations of
(-COO-) groups, indicating about additional ionic interactions. Decrease the beginning
evaporation temperature of polymer composites with increase concentration of protein filler,
indicating the destruction of the ordered structure of the polymer material revealed by
thermogravimetric analysis (TGA). The influence of various media, such as distilled water, saline
solution, and buffer solutions at differents pH on the swelling behavior of hydrogels was also
assessed. Maximum swelling capacity showed sample prepared with order of addition filler at the
end of synthesis (Scheme I). The kinetics of the release protein hydrolysate from the polymer
matrix was measurement by spectrophotometric method. The synthesized hydrogel composites
with protein hydrolysate and improved physicochemical properties are of practical interest as
water-retaining materials for increasing of crop the yield in agricultural
Influence of charge carriers on corrugation of suspended graphene
Electronic degrees of freedom are predicted to play a significant role in mechanics of two-dimensional crystalline membranes. Here we show that appearance of charge carriers may cause a considerable impact on suspended graphene corrugation, thus leading to additional mechanism resulting in charge carriers mobility variation with their density. This finding may account for some details of suspended graphene conductivity dependence on its doping level and suggests that proper modeling of suspended graphene-based device properties must include the influence of charge carriers on its surface corrugation
A New Algorithm for Analysis of Experimental Mössbauer Spectra
A new approach to analyze the nuclear gamma resonance (NGR) spectra is presented and justified in the paper. The algorithm successively spots the Lorentz lines in the experimental spectrum by a certain optimization procedures. In Mössbauer spectroscopy, the primary analysis is based on the representation of the transmission integral of an experimental spectrum by the sum of Lorentzians. In the general case, a number of lines and values of parameters in Lorentzians are unknown. The problem is to find them. In practice, before the experimental data processing, one elaborates a model of the Mössbauer spectrum. Such a model is usually based on some additional information. Taking into account physical restrictions, one forms the shape of the lines which are close to the normalized experimental Mössbauer spectrum. This is done by choosing the remaining free parameters of the model. However, this approach does not guarantee a proper model. A reasonable way to construct a structural NGR spectrum decomposition should be based on its model-free analysis. Some model-free methods of the NGR spectra analysis have been implemented in a number of known algorithms. Each of these methods is useful but has a limited range of application. In fact, the previously known algorithms did not react to hardly noticeable primary features of the experimental spectrum, but identify the dominant components only. In the proposed approach, the difference between the experimental spectrum and the known already determined part of the spectral structure defines the next Lorentzian. This method is effective for isolation of fine details of the spectrum, although it requires a well-elaborated algorithmic procedure presented in this paper
A NEW ALGORITHM FOR ANALYSIS OF EXPERIMENTAL MÖSSBAUER SPECTRA
A new approach to analyze the nuclear gamma resonance (NGR) spectra is presented and justified in the paper. The algorithm successively spots the Lorentz lines in the experimental spectrum by a certain optimization procedures. In Mössbauer spectroscopy, the primary analysis is based on the representation of the transmission integral of an experimental spectrum by the sum of Lorentzians. In the general case, a number of lines and values of parameters in Lorentzians are unknown. The problem is to find them. In practice, before the experimental data processing, one elaborates a model of the Mössbauer spectrum. Such a model is usually based on some additional information. Taking into account physical restrictions, one forms the shape of the lines which are close to the normalized experimental Mössbauer spectrum. This is done by choosing the remaining free parameters of the model. However, this approach does not guarantee a proper model. A reasonable way to construct a structural NGR spectrum decomposition should be based on its model-free analysis. Some model-free methods of the NGR spectra analysis have been implemented in a number of known algorithms. Each of these methods is useful but has a limited range of application. In fact, the previously known algorithms did not react to hardly noticeable primary features of the experimental spectrum, but identify the dominant components only. In the proposed approach, the difference between the experimental spectrum and the known already determined part of the spectral structure defines the next Lorentzian. This method is effective for isolation of fine details of the spectrum, although it requires a well-elaborated algorithmic procedure presented in this paper
Chemical composition of surface and structure of defects in diamond single crystals produced from detonation nanodiamonds
Spatially Resolved 3 micron Spectroscopy of Elias 1: Origin of Diamonds in Protoplanetary Disks
We present spatially resolved 3 um spectra of Elias 1 obtained with an
adaptive optics system. The central part of the disk is almost devoid of PAH
emission at 3.3 um; it shows up only at 30 AU and beyond. The PAH emission
extends up to 100 AU, at least to the outer boundary of our observation. The
diamond emission, in contrast, is more centrally concentrated, with the column
density peaked around 30 AU from the star. There are only three Herbig Ae/Be
stars known to date that show diamond emission at 3.53 um. Two of them have
low-mass companions likely responsible for the large X-ray flares observed
toward the Herbig Ae/Be stars. We speculate on the origin of diamonds in
circumstellar disks in terms of the graphitic material being transformed into
diamond under the irradiation of highly energetic particles.Comment: 7 pages, 4 figures, Accepted for publication in the Astrophysical
Journ
Unraveling the GO nitrogen doping during the Hummers oxidation, conversion and effect of nitrogen species on the electrical conductivity after thermal annealing
From graphene oxide towards aminated graphene facile synthesis, its structure and electronic properties
In this paper we present a facile method for the synthesis of aminated graphene derivative through simultaneous reduction and amination of graphene oxide via two-step liquid phase treatment with hydrobromic acid and ammonia solution in mild conditions. The amination degree of the obtained aminated reduced graphene oxide is of about 4 at.%, whereas C/O ratio is up to 8.8 as determined by means of X-ray photoelectron spectroscopy. The chemical reactivity of the introduced amine groups is further verified by successful test covalent bonding of the obtained aminated graphene with 3-Chlorobenzoyl chloride. The morphological features and electronic properties, namely conductivity, valence band structure and work function are studied as well, illustrating the influence of amine groups on graphene structure and physical properties. Particularly, the increase of the electrical conductivity, reduction of the work function value and tendency to form wrinkled and corrugated graphene layers are observed in the aminated graphene derivative compared to the pristine reduced graphene oxide. As obtained aminated graphene could be used for photovoltaic, biosensing and catalysis application as well as a starting material for further chemical modifications
Functionalization of Carbon Nanomaterial Surface by Doxorubicin and Antibodies to Tumor Markers
The actual task of oncology is effective treatment of cancer while causing a minimum harm to the patient. The appearance of polymer nanomaterials and technologies launched new applications and approaches of delivery and release of anticancer drugs. The goal of work was to test ultra dispersed diamonds (UDDs) and onion-like carbon (OLCs) as new vehicles for delivery of antitumor drug (doxorubicin (DOX)) and specific antibodies to tumor receptors. Stable compounds of UDDs and OLCs with DOX were obtained. As results of work, an effectiveness of functionalization was 2.94 % w/w for OLC-DOX and 2.98 % w/w for UDD-DOX. Also, there was demonstrated that UDD-DOX and OLC-DOX constructs had dose-dependent cytotoxic effect on tumor cells in the presence of trypsin. The survival of adenocarcinoma cells reduced from 52 to 28 % in case of incubation with the UDD-DOX in concentrations from 8.4–2.5 to 670–20 μg/ml and from 72 to 30 % after incubation with OLC-DOX. Simultaneously, antibodies to epidermal growth factor maintained 75 % of the functional activity and specificity after matrix-assisted pulsed laser evaporation deposition. Thus, the conclusion has been made about the prospects of selected new methods and approaches for creating an antitumor agent with capabilities targeted delivery of drugs
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