Unit Surface Research Articles

Microporous Carbon Nitride (C3 N5.4 ) with Tetrazine based Molecular Structure for Efficient Adsorption of CO2 and Water.

Mesoporous carbon nitrides with C3 N5 and C3 N6 stoichiometries created a new momentum in the field of organic metal-free semiconductors owing to their unique band structures and high basicity. Here, we report on the preparation of a novel graphitic microporous carbon nitride with a tetrazine based chemical structure and the composition of C3 N5.4 using ultra-stable Y zeolite as the template and aminoguanidine hydrochloride, a high nitrogen-containing molecule, as the CN precursor. Spectroscopic characterization and density functional theory calculations reveal that the prepared material exhibits a new molecular structure, which comprises two tetrazines and one triazine rings in the unit cell and is thermodynamically stable. The resultant carbon nitride shows an outstanding surface area of 130.4 m2 g-1 and demonstrates excellent CO2 adsorption per unit surface area of 47.54 μmol m-2 , which is due to the existence of abundant free NH2 groups, basic sites and microporosity. The material also exhibits highly selective sensing over water molecules (151.1 mmol g-1 ) and aliphatic hydrocarbons due to its unique microporous structure with a high amount of hydrophilic nitrogen moieties and recognizing ability towards small molecules.

Microporous Carbon Nitride (C3N5.4) with Tetrazine based Molecular Structure for Efficient Adsorption of CO2 and Water

AbstractMesoporous carbon nitrides with C3N5 and C3N6 stoichiometries created a new momentum in the field of organic metal‐free semiconductors owing to their unique band structures and high basicity. Here, we report on the preparation of a novel graphitic microporous carbon nitride with a tetrazine based chemical structure and the composition of C3N5.4 using ultra‐stable Y zeolite as the template and aminoguanidine hydrochloride, a high nitrogen‐containing molecule, as the CN precursor. Spectroscopic characterization and density functional theory calculations reveal that the prepared material exhibits a new molecular structure, which comprises two tetrazines and one triazine rings in the unit cell and is thermodynamically stable. The resultant carbon nitride shows an outstanding surface area of 130.4 m2 g−1 and demonstrates excellent CO2 adsorption per unit surface area of 47.54 μmol m−2, which is due to the existence of abundant free NH2 groups, basic sites and microporosity. The material also exhibits highly selective sensing over water molecules (151.1 mmol g−1) and aliphatic hydrocarbons due to its unique microporous structure with a high amount of hydrophilic nitrogen moieties and recognizing ability towards small molecules.

Surface thermodynamics of 2-chloroethanol with 2-dimethylaminoethanol and 2-diethylaminoethanol at different temperatures

ABSTRACT The surface tension of binary mixtures of 2-chloroethanol with 2-dimethylaminoethanol (DMAE) and 2-diethylaminoethanol (DEAE) was measured over the entire composition range at the temperatures 293.15 K to 313.15 K and atmospheric pressure. The excess values of surface tension were correlated with the Redlich-Kister polynomial equation. The experimental surface tension was correlated with five different theoretical models. The Hilderbrand and Scott theories for ideal solutions (HSIS) and their extensions of Guggenheim’s equation (HSEG), Volume Fraction Statistics, Sudgen method and modified New Parachor method were applied to determine the values of surface tension in the binary solvent systems. The surface tension data were further used to determine the surface thermodynamic properties such as surface entropy (SS) and surface enthalpy (HS) per unit surface area. The results have brought about some useful information on the extent of molecular interactions between the unlike molecules occurring at the surface and bulk.

A Review on Gas-Liquid Mass Transfer Coefficients in Packed-Bed Columns

This review provides a thorough analysis of the most famous mass transfer models for random and structured packed-bed columns used in absorption/stripping and distillation processes, providing a detailed description of the equations to calculate the mass transfer parameters, i.e., gas-side coefficient per unit surface ky [kmol·m−2·s−1], liquid-side coefficient per unit surface kx [kmol·m−2·s−1], interfacial packing area ae [m2·m−3], which constitute the ingredients to assess the mass transfer rate of packed-bed columns. The models have been reported in the original form provided by the authors together with the geometric and model fitting parameters published in several papers to allow their adaptation to packings different from those covered in the original papers. Although the work is focused on a collection of carefully described and ready-to-use equations, we have tried to underline the criticalities behind these models, which mostly rely on the assessment of fluid-dynamics parameters such as liquid film thickness, liquid hold-up and interfacial area, or the real liquid paths or any mal-distributions flow. To this end, the paper reviewed novel experimental and simulation approaches aimed to better describe the gas-liquid multiphase flow dynamics in packed-bed column, e.g., by using optical technologies (tomography) or CFD simulations. While the results of these studies may not be easily extended to full-scale columns, the improved estimation of the main fluid-dynamic parameters will provide a more accurate modelling correlation of liquid-gas mass transfer phenomena in packed columns.

Intensity comparison between UV lamps and plasma emission for air purification studies

We compared spectra and intensity light of different sources, such as a UV-A lamp, a UV-C lamp, and a visible bulb, and atmospheric nonthermal plasma emission. Spectroscopic measurements were performed with an optical emission spectrometer and radiometric measurements with a radiometer to which UV-A, UV-C, and visible probes were coupled to measure the light intensity per unit surface. For each light source, we measured the emission spectrum and light intensity using different probes and also varying the relative distance. The nonthermal atmospheric plasma was generated by means of a surface barrier dielectric discharge varying the relevant parameters. This work allowed us to create the experimental setup suitable for further studies on volatile organic compound abatement by plasma-catalysis processing and compared it to the photocatalysis techniques based on UV and visible lamps.

Cr(VI) immobilization by FeS-coated alumina and silica: Effects of pH and surface coating density

We investigated the feasibility of using FeS-coated alumina and silica for permeable reactive barrier (PRB) applications. By both coated materials, Cr(VI) was reduced to Cr(III), which was immobilized via surface complexation/precipitation at acidic pH, and bulk precipitation at neutral to basic pH. Both pH and surface coating density (the amount of FeS deposits per unit surface area of a supporting matrix) controlled Cr(VI) reduction capacity and [Cr,Fe](OH)3 composition. The reduction was higher at acidic pH due to lower passivation, as evidenced by the increased production of Fe(III) (oxyhydr)oxides over Fe(II)-Fe(III) phases. The coated alumina, despite the lower amount of FeS deposits than the coated silica, showed greater reduction capacities due to its higher surface coating density, which made Fe(III) closer together to favor Fe(III) (oxyhydr)oxide formation. Since Cr(III) was preferentially substituted for Fe(III) in Fe(III) (oxyhydr)oxides, lower pH and higher surface coating density led to lower Cr fractions in [Cr,Fe](OH)3 because of the increased production of Fe(III) (oxyhydr)oxides. Given that Cr-poor [Cr,Fe](OH)3 is more resistant to re-oxidation, FeS-coated alumina is better for PRB applications. This study reveals the significance of the surface coating density when evaluating the effectiveness of coated materials in redox-based treatments.

Removal of Particulate Matters by Using Zeolitic Imidazolate Framework-8s (ZIF-8s) Coated onto Cotton: Effect of the Pore Size of ZIF-8s on Removal.

Removal of particulate matter (PM) like PM2.5 and PM10 from air was carried out with cotton coated with metal-organic frameworks (MOFs) having various pore sizes to understand the effect of the pore size of MOFs (here, ZIF-8s) on the performances in PM elimination. Both removal efficiency and quality factor, based on the unit surface area of ZIF-8s, in the filtration of PMs with ZIF-8/cotton did not rely considerably on the pore size of ZIF-8s. More importantly, small pores (even less than 0.5 nm) of conventional MOFs like ZIF-8 are more than enough in the elimination of large PMs like PM10 with a size of microns probably because small active sites (such as polar functional groups) on PMs can interact with porous materials having polarity. Additionally, electrostatic interactions between PMs and porous materials could be confirmed as a plausible mechanism for PM removal with ZIF-8/cotton.

The Electro-oxidation of Hydrazine with Palladium Nanoparticle Modified Electrodes: Dissecting Chemical and Physical Effects: Catalysis, Surface Roughness, or Porosity?

Palladium nanoparticles in the form of a layer on the surface of an electrode are shown to be electrocatalytic with respect to the four-electron oxidation of hydrazine to form dinitrogen. Quantitative voltammetry shows that the reduced overpotential in comparison with both carbon and bulk palladium electrodes partly arises from the increased surface area of the interface and partly from an increased catalytic activity of the nanoparticles relative to the bulk material. The relative catalytic activity per unit surface area of the nanoparticles as compared with the bulk material is shown to be ca. 35-45.

Multiscale Investigation into Chemically Stable NASICON Solid Electrolyte in Acidic Solutions.

Natrium superionic conductor (NASICON) solid electrolyte has been attracting wide attention due to its high ionic conductivity, low cost, and environmental friendliness. In this work, the chemical stability of the NASICON solid electrolyte with the composition of Na3Zr2Si2PO12 was evaluated in acidic solutions with different pH values, and the corrosion mechanism of the NASICON solid electrolyte was revealed at the multiscale level. Variations in bulk impedance, grain boundary impedance, and surface crack impedance with immersion time were determined by an AC impedance method. Comprehensive studies upon scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) etching, X-ray diffraction (XRD), and Raman spectroscopy, the morphological transformation, degradation limit depth, Cl- penetration effect, and proton exchange between H3O+ and Na+ were examined ranging from macro- and meso- to microscales, respectively. With the decrease of the pH of the solution, the exchange rate between H3O+ and Na+ protons increases. The lack of Na+ within the crystallographic lattice leads to the shrinkage of phosphorus-oxygen tetrahedra, which is the main reason for the decrease of unit cell volume, grain refinement, and surface cracks gradually. This work features multiscale characterizations of crystal structure, grain boundaries, surface morphology changes, and Na+ transport, which deepens our physicochemical understanding of solid electrolytes with high chemical stability.

Evaluation of the effects of some watershed characteristics on water and suspended sediment yield in agricultural and forest dominated watersheds

Topography, geological structure and land use play a determinative role in the streamflow and total suspended sediment yield of watersheds having similar climate, soil and vegetation characteristics. In order to facilitate sustainable water resource management and effective land use planning, there is an increasing need for research investigating the effects of these factors. This study was carried out in forested and agricultural dominated subwatersheds of the Big Melen watershed in the Western Black Sea Region of Turkey. Hazelnut plantations are grown on most of the agricultural areas in both watersheds. The forested watershed has a steep topography and its geological structure consists of sandstone-mudstone and sedimentary rock. The agricultural watershed area is larger and unlike the forested watershed, there is argillaceous limestone in its geological structure. The precipitation, streamflow and total suspended sediment yield in the watersheds were measured for two years. The total precipitation of the study area over the two years was 2217.3 mm. The water yield of the forested watershed was 867.6 mm, while that of the agricultural watershed was 654.9 mm. In the two years, the total suspended sediment transported from the forested watershed was 19.51 t ha<sup>-1</sup> and from the agricultural watershed 7.70 t ha<sup>-1</sup>. However, except for the high values measured after an extreme rainfall event, the unit surface suspended sediment yield of the agricultural watershed was found to be higher than that of the forested watershed. These findings showed that watershed characteristics such as slope, geological structure and rainfall intensity may be more effective on the streamflow and total suspended sediment yield of the watersheds than land use.

РАЗРАБОТКА УСЛОВИЙ ХРАНЕНИЯ ТАЛИЕВОЙ АМАЛЬГАМЫ

It has been established that lNH2SO4 solution and distilled water can be used as a protective medium for a long-term storage (30-40 days) of thallium amalgam of eutectic composition (8.6 mas.%), without sliming of its surface and an insignificant change of its concentration. An inverse dependence between the decomposition reaction rate and the ratio of the solution volume per unit of the contact surface (V:S), which corresponds to the height of the liquid layer (h) above the amalgam, is observed. At h ~ 2.5 cm and higher, the reaction rate becomes stabilized. The value of metal loss during its storage for 10-15 days does not exceed 0.5-1.0 mas.% of the initial thallium content in the amalgam. It has been shown that the rate of dissolution of thallium from amalgam is rather low, and in sulfuric acid solution it is only slightly higher than that in water with all S:V ratios. A similar picture is observed upon thallium amalgam decomposition in the same media in an open vessel; the difference consists only in a higher K value (Table 4). Thus, with S:V = 1:2.5, in an open vessel K in lNH2SO4 makes up 10,5.1011 mol/cm2.sec, and in H2O – 7.3.1011 mol/cm2.sec, whereas in a closed vessel K in lNH2SO4 makes up 1,9.1011 mol/cm2. sec, and in H2O – 1.5.1011 mol/cm2.sec. For 40 days of thallium amalgam (8.54 mas.%) storage in 1NH2SO4 the loss of thallium has been 1.3 mas.%, and in the distilled water - 1 mas.%. The quantity of the dissolved metal increases in proportion to the experiment duration, which is characteristic for a zero-order reaction, and this dependence is observed for all S:V ratios from 1:1 to 1:7. Besides, a possibility to use some saturated hydrocarbons, wherein no sliming of thallium amalgam occurs, as a protective wash liquid has been shown.

RETRACTED ARTICLE: Synthesis and characterization of magnetite/hydroxyapatite nanoparticles for biomedical applications

During the last few decade, magnetite/hydroxyapatite nanoparticles have attracted much attention for its potential applications in the field of medicine and controlled drug delivery. In the present work, we have intended and synthesized, magnetite/hydroxyapatite nanoparticles by wet-chemical precipitation route. The thermal decomposition of the prepared sample was carried out by Thermogravimetric and Differential Scanning Calorimetry (TG/DSC) analysis upto 1000 °C, it showed that the sample was stable up to 919.2 °C. The phase formation, functional groups, morphology and magnetic property of as-prepared and annealed samples were characterized using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), micro Raman, Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM) and vibrating-sample magnetometer (VSM). By adopting Scherer method detailed structural analysis like the crystallite size, strain, dislocation density, lattice parameter, unit cell volume, surface area and fraction of crystallinity were calculated for as-prepared and annealed HAP samples. The average crystallite size of the as-prepared, annealed at 700 °C, 800 °C and 900 °C are 39, 46, 51 and 65 nm, respectively. The dislocation density, strain and surface area were decreased. FT-IR and Raman spectra showed both as-prepared and annealed samples possessed the characteristic bands of HAP. FE-SEM and TEM images depicted and confirmed the morphological characteristics of HAP. The VSM analysis confirmed that both as-prepared and annealed samples of HAP are in diamagnetic nature. The dielectric constant of as-prepared and annealed samples decreased with increase in annealing temperature whereas the conductivity increases with increase in frequency. The antibacterial property of apatite samples depending on the types of bacterial strains and also activity changed with the crystallite size.

Deposition Characteristics of Firebrands on and Around Rectangular Cubic Structures

The focus of the present work is on the deposition of firebrands in a flow over a rectangular cubic block representative of a structure in wildland-urban interface (WUI). The study was carried out by physics based modeling where the wind flow turbulence was dealt with by large eddy simulation (LES) and firebrands were treated by Lagrangian tracking. The Lagrangian equations coupled with the flow solver, accounted for both translational and rotational motions as well as thermochemical degradation of firebrands, assumed to be cylindrical. The dimensions of the structure were varied from 3 to 9 m in the simulations for a parametric study. The simulations were carried out by tracking many firebrands randomly released with a uniform distribution from a horizontal plane 35 m above the ground into the computational domain. The coordinates of the deposited firebrands were used to calculate their normalized number density (number of landed firebrands per unit surface area) to quantify their deposition pattern. On the leewardside of the block, an area, referred to as the safe zone, was identified right behind the structure where firebrands never deposit. The size of the safe zone in the direction perpendicular to the wind was nearly identical to the width of the structure. The length of the safe zone in the wind direction was proportional to the height of the structure. The leeward face of the blocks was never hit by a firebrand. The windward face was hit by many more firebrands than the lateral faces but much less than the top face. The distribution of the number density of the deposited firebrands on the top face was found to be correlated with the flow separation and reattachment on this face.

Cu1.5Mn1.5O4 spinel type composite oxide modified with CuO for synergistic catalysis of CO oxidation

Composite oxides of copper and manganese are widely used in oxidation reactions, and the main active component is copper-manganese spinel, whereas the copper oxide and manganese oxide show extremely low activity, despite that they are beneficial for CO oxidation. In this paper, it was found that the synergistic effect of Cu1.5Mn1.5O4 and CuO can promote the catalytic oxidation of CO. The catalysts were prepared using the citric acid complexation method and they were characterized through combined the techniques of N2-adsorption desorption, XRD, H2-TPR, TEM, CO-TPD and O2-TPD. The catalytic performance of various catalysts in CO oxidation was then evaluated. The results confirmed that Cu1.5Mn1.5O4 modified with CuO exhibited the best catalytic performance and the highest unit surface activity (defined as the CO conversion rate per unit surface area of catalyst). CuO and Cu1.5Mn1.5O4 had a synergistic effect, where O2 was activated by CuO and it then interacted with CO, activated by Cu1.5Mn1.5O4, to form CO2, thus increasing the catalytic activity.

Solar Dryer with Integrated Energy Unit

The work is devoted to the issue of the rational use of the solar energy in the technological process of fruit drying based on the use of solar drying devices, which are applied in various sections of the agro-industrial centers of Ukraine. The aim of this research was intensification of the fruits drying process using the solar energy by combining an air collector and drying chamber into a single power unit. To achieve the aim the heat exchange diagnostic techniques with alternative potentials of diffusion and moisture transfer was developed. This technique differs from those existing for the heat exchange research in that it allows the intensity of the moisture evaporation from a unit of the material surface to be calculated, based on the synthesis of the moisture content and the irreversible major laws of processes of the heat exchange characteristics of the fruits drying using the solar dryer. The above model makes it possible to diagnose the heat exchange processes and analyze the mathematical model of the heat exchange processes. It also allows modeling the changeable diffusion and moisture transfer potentials based on the dependences obtained and for the purpose of a further application in the methods and devices development to control the strain-deformed state of the fruits during the drying process. The method is offered for the calculation of diffusion and moisture transfer during drying fruits in the solar dryer.

Geometrical Layout Effect on Light Intensity Distribution in SSI-LED

Like the light emission phenomenon in an incandescent light bulb, Kuo’s group have reported a broad-band white light emission from a new type of solid-state incandescent light emitting device (SSI-LED) (1-4). The device is a simple metal-oxide-semiconductor (MOS) capacitor with a high-k gate dielectric deposited over a p-type Si wafer (1-4). On hard breakdown of the dielectric, nano-sized conductive paths (or, nano-resistors) are formed in the high-k stack. Large passage of current through these conductive paths results in light emission due to the thermal excitation. SSI-LEDs have been shown to have very high color rendering index (CRI) of up to 97.9 (4). This indicates that the light emission process from the conductive paths is close to black body radiation phenomenon. This fact along with temperature estimates made for nano-resistors using simple energy balance-based calculations has been previously utilized to perform light intensity distribution calculations over SSI-LED. (5) In this paper, the authors adapt a similar approach and study the effect of geometrical layout of nano-resistors on the emitted light intensity distribution from SSI-LED at higher magnifications.Stefan-Boltzmann law quantitates the total energy radiated per unit surface area of a black body across all wavelengths per unit time j^* and is directly proportional to the fourth power of the black body's temperature T. If a black body of surface area A is radiating energy to the surroundings at temperature Tc, the net power radiated can be accounted as given in equationP=Aeσ(T4-Tc4) (1)where e is the emissivity of the object and σ is the Stefan–Boltzmann constant. Under the assumption that the nano-resistors formed in the dielectric act as point light sources, emitted light intensity at certain distance from the nano-resistors can be calculated by following inverse-square law. The resultant intensity from all the nano-resistors at any given point in space is simply the scalar addition of radiation intensity from each of the individual nano-resistors, i.e., if I1, I2...., IN are the radiation intensities due to N nano-resistors at a point in space then resultant intensity,Iresultant = I1+ I2+I3.........+ IN Reasonable assumptions are made for various physical parameters while performing radiation intensity distribution calculations. For example, nano-resistors with circular cross-sections were assumed to form in the high-k dielectric. Three different diameter sizes of nano-resistors are considered – 20 nm, 50 nm and 100 nm. Four different layout configurations (linear, triangular, square, and face-centered square) of nano-resistors are studied for localized light intensity distribution calculations based on the two-dimensional Bravais lattice symmetries. Intensity calculations are done for two cases. In the first case, nano-resistors of same sizes are considered in all the different geometrical layout configurations. In the second case, larger sized nano-resistors of diameter 100 nm are formed in the vicinity of smaller sized nano-resistor keeping the geometrical layout to be same. The light absorption by ITO gate in the SSI-LED is accounted using Beer-Lambert’s law.The geometrical layout of the nano-resistors formed in the SSI-LED affected the local light intensity distribution at higher magnifications and will be presented and discussed in detail. The simulated distribution could be correlated to the experimentally observed light dot patterns formed in SSI-LED at higher magnifications, as shown in figure 1 (6).1. Y. Kuo and C.-C. Lin, Appl. Phys. Lett., 102, 031117 (2013).2. Y. Kuo and C.-C. Lin, ECS Solid-State Lett., 2, Q59 (2013).3. Y. Kuo and C.-C. Lin, Solid-State Electron., 89, 120 (2013).4. C.-C. Lin and Y. Kuo, Appl. Phys. Lett., 106, 121107 (2015).5. A. Shukla and Y. Kuo, Prime 2020, #H04-1965 (2020)6. C.-C. Lin, PhD. Thesis, Texas A&M University, College Station, Texas (2014). Figure 1

Jointed Plain Concrete Pavements in Airports: Structural–Economic Evaluation and Proposal for a Catalogue

Although the design of jointed plain concrete pavements could be solved by commercial software, there is still a need for simple tools to be used in feasibility studies and preliminary cost–benefit analyses. This paper analyzed and verified jointed plain concrete pavements for airports composed of square slabs without tie and dowel bars. The examined slabs are laid on a cement-treated base layer and a stabilized granular subbase layer. The finite element software FAARFIELD was used to design the JPCP pavements when they are subjected to the design of the airplane (i.e., turboprop C-130J Hercules) under different conditions. Seven subgrade load bearing capacity values, twenty traffic levels, and two construction hypotheses (i.e., constant or variable thickness of the two deeper layers) were designed and then verified with the Westergaard theory in order to present a proposal for a catalogue. Finally, the construction cost per unit surface area was calculated for different construction methods of paving (by slip form paver or by fixed form). The obtained results provide a simple and fast procedure to design preliminary airport JPCPs.

Molecular-level understanding of gibbsite particle aggregation in water

Using molecular dynamics simulations, we investigate the molecular scale origin of crystal face selectivity when one gibbsite particle attaches to another in water. A comparison of the free energy per unit surface area of particle–particle attachment indicates that particle attachment through edge surfaces, where the edge surfaces are either (1 0 0) or (1 1 0) crystal faces, is more energetically favorable compared to attachment between two basal surfaces (i.e., (0 0 1) crystal faces) or between the basal surface of one particle and the edge surface of another. This result suggests that gibbsite crystals with low basal/edge surface area ratio will preferentially attach through edge surfaces, potentially helping the crystals grow laterally. However, for larger gibbsite particles (high basal/edge surface area ratio) the total free energy, not normalized by surface area, of particle attachment through the basal surfaces is lower (more negative) than attachment through the edge surfaces, indicating that larger gibbsite particles will preferentially aggregate through basal surface attachments. The short-range electrostatic interactions including the interparticle hydrogen bonds from surface –OH groups drive particle attachment, and the dominant contribution to the free energy minimum is enthalpic rather than entropic. However, the enthalpy of basal-edge attachment is significantly offset by the entropy leading to a higher free energy (less negative) compared to that of basal-basal attachment. Study of the free energy for a few imperfect attachments of two particles indicates a higher free energy (i.e., less negative, less stable), compared to a perfect attachment

Quartz Crystal Microbalance (QCM) Based Biosensor Functionalized by HER2/neu Antibody for Breast Cancer Cell Detection

The heterogeneity and metastatic features of cancer cells lead to a great number of casualties in the world. Additionally, its diagnosis as well as its treatment is highly expensive. Therefore, development of simple but effective diagnostic systems which detect the molecular markers of cancer is of great importance. The molecular changes on cancer cell membranes serve as targets, such as HER2/neu receptor which is detected on the surface of highly metastatic breast cancer cells. We have aimed to develop a specific and simple quartz crystal microbalance (QCM)-based system to identify HER2/neu expressing breast cancer cells via a receptor-specific monoclonal antibody. First, the QCM chip was coated with polymeric nanoparticles composed of hydroxyethylmethacrylate (HEMA) and ethylene glycol dimethacrylate (EDMA). The nanoparticle coated QCM chip was then functionalized by binding of HER2/neu antibody. The breast cancer cells with/without HER2/neu receptor expression, namely, SKBR3, MDA-MB 231 and also mouse fibroblasts were passed over the chip at a rate of 10–500 cells/mL and the mass changes (Δm) on cell/cm2 unit surface of sensor were detected in real-time. The detection limit of the system was 10 cells/mL. Thus, this QCM-based HER2/neu receptor antibody functionalized system might be used effectively in the detection of HER2/neu expressing SKBR3 breast cancer cells.

OBTAINING BIODEGRADABLE COMPOSITE MATERIALS BASED ON POLYOLEFINS AND HUSK OF SUNFLOWER SEEDS

The paper presents the results of a comparative study of physical and mechanical, rheological, and biodegradable characteristics of a mixture containing low- and high-pressure polyethylene (HDPE 273-83 and HDPE 15303-003, respectively) in a 1:1 ratio filled with finely ground (less than 200 microns) sunflower husk (5-30% by weight). The mixture also contained 10% compatibilizer (functionalized by the method of alkaline alcoholysis of sevilen (SEVA 12206-007) and 1% of technological additive (polyethylene glycol (PEG-115 (4000). It has been established that as the content of the plant filler increases (up to 25%), the elastic modulus and tensile strength has not practically changed. The relative elongation of the composite under tension exceeds 100% (with a sunflower husk content up to 15% by weight). The complex viscosity and shear modulus of the considered melts with different filler contents are almost at the same level. The introduction of sunflower husk (up to 30%) and compatibilizer (10%) helps to reduce the viscosity and elasticity of the melts, which is evidence of a significant improvement in the processability of the compositions compared to HDPE 273-83. For a comparative assessment of composites biodegradability, moisture absorption, chemical oxygen consumption, and composites mass loss in laboratory soil during exposure for 12 months were being studied. It is shown that with increasing filler content, the ability of composites to biodegradation increases. In addition, it was found that the indicator of chemical oxygen consumption per unit surface area of the sample is a more productive and reproducible estimate in comparison with traditional methods for assessing the degradability of composite materials.