Values Of Surface Density Research Articles

FEASTS Combined with Interferometry. II. Significantly Changed H i Surface Densities and Even More Inefficient Star Formation in Galaxy Outer Disks

We update the H i surface density measurements for a subset of 17 THINGS galaxies by dealing with the short-spacing problem of the original Very Large Array (VLA) H i images. It is the same sample that Bigiel et al. used to study the relation between H i surface densities and star formation (SF) rate surface densities in galaxy outer disks, which are beyond the optical radius r 25. For 10 galaxies, the update is based on combining original THINGS VLA H i images with H i images taken by the single-dish FAST in the FEASTS program. The median increment of H i surface densities in outer disks is 0.15–0.4 dex at a given new H i surface density. Several galaxies change significantly in the shape of radial profiles H i surface densities, and seven galaxies are now more than 1σ below the H i size–mass relation. We update the H i star formation laws in outer disks. The median relation between the H i surface densities and SF rate surface densities based on pixel-wise measurements shifts downward by around 0.15 dex because the H i surface density values shift rightward, and the scatter increases significantly. The scatter of the relation, indicating the star-forming efficiency, exhibits a much stronger positive correlation with the stellar mass surface density than before. Thus, detecting the previously missed, diffuse H i due to the short-spacing problem of the Very Large Array observations is important in revealing the true condition and variation in SF possibly regulated by stellar feedbacks in the localized environment of outer disks.

Determination of surface density of nonporous membranes with ultrasonic immersion measurements

ABSTRACT The surface density of nonporous membranes is estimated with a conventional ultrasonic immersion measurement system without need for a priori information about the membrane such as wave speed, density, thickness or impedance under most testing conditions. The derivation, theoretical limitations and practical restrictions of the technique are discussed. The broadband nature of the measurement allows the surface density values to be estimated at multiple discrete frequencies within the useful bandwidth of the transducer. In experimentation, the technique was used to measure surface densities in a range of 0.044–0.328 kg/m2. All calculated surface densities are within 5% or less of their nominal values with an average percent difference of 1.7%.

Modeling the impact of asteroids over Mexican territory

This work focuses on knowing the physical, environmental and population effects from the impact of an asteroid occurring in the Mexican territory. The work consists of the adaptation of routines product of previous works in the literature to generate a numerical code written in PyThon that allowed modeling this kind of phenomenon. Firstly, a map of the superficial densities of the Mexican territory has been developed with a resolution of $0.5^\circ$ of longitude by $0.5^\circ$ of latitude of the Earth. The map allows us to find the value of surface density in a specific geological area of the country. Once the surface density value was obtained, it is established as the value of the impact site (target). The model requires using fixed parameters, such as the diameter of the body, its density or mass, the angle of incidence and the density value at the impact site. The output, provides the impact velocity, as well as the energy released, diameter and depth of the crater, the magnitude of the earthquake as well as the damage on the surface. We studied the Chicxulub asteroid event in two hypothetical scenarios. Firstly, the atmospheric density profile was modified, allowing the calculation of a new value for the impact velocity. Secondly, we assume that the object hits with a fraction of the initial mass, and with this the impact velocity and its effects were recalculated for three different targets. They were used to calculate the infrastructure damage they would cause if the impact could occur today. Finally, the results obtained by our model were compared with the literature, showing that they are consistent with the observational data. Models such as this one contribute to having tools for the attention towards the prevention of this kind of event that in the context of the study risks from the space are necessary in Mexico.

Chaotic Capture of a Retrograde Moon by Venus and the Reversal of Its Spin

Planets are surrounded by fractal surfaces (traditionally called Hill spheres), separating the inner zones of long-term stable orbital motion of their satellites from the outer space where the gravitational pull from the Sun takes over. Through this surface, external minor bodies in trajectories loosely co-orbital to a planet can be stochastically captured by the planet without any assistance from external perturbative forces, and can become moons chaotically orbiting the planet for extended periods of time. Using state-of-the-art orbital integrators, we simulate such capture events for Venus, resulting in long-term attachment phases by reversing the forward integration of a moon initially attached to the planet and escaping it after an extended period of time. Chaotic capture of a retrograde moon from a prograde heliocentric orbit appears to be more probable because the Hill sphere is almost four times larger in area for a retrograde orbit than for a prograde orbit. Simulated capture trajectories include cases with attachment phases up to 860,000 years for prograde moons and up to 370,000 years for retrograde moons. Although the probability of a long-term chaotic capture from a single encounter is generally low, the high density of co-orbital bodies in the primordial protoplanetary disk makes this outcome possible, if not probable. The early Venus was surrounded by a dusty gaseous disk of its own, which, coupled with the tidal dissipation of the kinetic energy in the moon and the planet, could shrink the initial orbit and stabilize the captured body within the Hill surface. The tidal torque from the moon, for which we use the historical name Neith, gradually brakes the prograde rotation of Venus, and then reverses it, while the orbit continues to decay. Neith eventually reaches the Roche radius and disintegrates, probably depositing most of its material on Venus’ surface. Our calculations show that surface density values of about 0.06 kg m−2 for the debris disk may be sufficient to stabilize the initial chaotic orbit of Neith and to bring it down within several radii of Venus, where tidal dissipation becomes more efficient.

Anisotropic strange stars and its maximum mass in Finch-Skea geometry in dimensions D ≥ 4

In this article, we have demonstrated a stellar model for compact stars in the presence of strange matter embedded in D ≥ 4 dimensional space-time defined by the Finch-Skea metric. To study the relevant physical properties of the interior matter, we consider the equation of state (henceforth EOS) as proposed in the MIT bag model, where B is termed the bag constant. The mass-radius relationship in four and higher dimensions is determined using the range of values of surface density through the relation ρ s = 4B, for which bulk strange matter may be a viable issue for compact objects. Here, we choose the range of B so that stable strange matter may exist relative to a neutron at zero external pressure. We note that a maximum value of the stellar radius exists when B is fixed at a given allowed value for which metric functions considered to be real here. This is the maximum allowed radius in this model, which depends on the surface density of a strange star. In four dimensions, the compactness of a star is found to be greater than 0.33. In the case of higher dimensions (D > 4), we observed different values of compactness. Causality conditions are satisfied interior to the star up to the maximum allowed radius , for which the metric function is real. The validity of the energy conditions, surface redshift and other parameters of the stellar configuration are studied, and new results are found. The stability of the model is also studied.

Forming rocky exoplanets around K-dwarf stars

Context. New space telescopes, such as the upcoming PLATO mission, aim to detect and study thousands of exoplanets, especially terrestrial planets around main-sequence stars. This motivates us to study how these planets formed. How multiple close-in super-Earths form around stars with masses lower than that of the Sun is still an open issue. Several recent modeling studies have focused on planet formation around M-dwarf stars, but so far no studies have focused specifically on K dwarfs, which are of particular interest in the search for extraterrestrial life. Aims. We aim to reproduce the currently known population of close-in super-Earths observed around K-dwarf stars and their system characteristics. Additionally, we investigate whether the planetary systems that we form allow us to decide which initial conditions are the most favorable. Methods. We performed 48 high-resolution N-body simulations of planet formation via planetesimal accretion using the existing GENGA software running on GPUs. In the simulations we varied the initial protoplanetary disk mass and the solid and gas surface density profiles. Each simulation began with 12 000 bodies with radii of between 200 and 2000 km around two different stars, with masses of 0.6 and 0.8 M⊙. Most simulations ran for 20 Myr, with several simulations extended to 40 or 100 Myr. Results. The mass distributions for the planets with masses between 2 and 12 M⊕ show a strong preference for planets with masses Mp < 6 M⊕ and a lesser preference for planets with larger masses, whereas the mass distribution for the observed sample increases almost linearly. However, we managed to reproduce the main characteristics and architectures of the known planetary systems and produce mostly long-term angular-momentum-deficit-stable, nonresonant systems, but we require an initial disk mass of 15 M⊕ or higher and a gas surface density value at 1 AU of 1500 g cm−2 or higher. Our simulations also produce many low-mass planets with M < 2 M⊕, which are not yet found in the observed population, probably due to the observational biases. Earth-mass planets form quickly (usually within a few million years), mostly before the gas disk dispersal. The final systems contain only a small number of planets with masses Mp > 10 M⊕, which could possibly accrete substantial amounts of gas, and these formed after the gas had mostly dissipated. Conclusions. We mostly manage to reproduce observed K-dwarf exoplanetary systems from our GPU simulations.

Computerized histomorphometry in the diagnosis of pre-malignant endometrial lesions

Accurate diagnosis of precursors to endometrial cancer is a major challenge to pathologists. D-score is well reproducible and predictive of prognosis than the WHO schema, however it is not widely available, this study is an attempt to design a simple workstation for estimation of D-score. Fifteen samples of endometrium with low grade hyperplasia, fifteen proliferative and eight secretory phase endometria were analyzed by light microscopy and stereology. Severeal architectural and karyometric parameters were evaluated and the D-score was calculated. The volume density of stroma (VPS) was significantly higher in proliferative than secretory and hyperplastic endometria. Among the three diagnostic groups, secretory phase endometria have -significantly- the least VPS. The mean values of glandular surface density (outSD) were higher in secretory endometria as compared to proliferative and hyperplastic endometria, however, the differences was statistically insignificant. All of evaluated nuclear parameters are insignificantly differ between hyperplastic and proliferative endometria. The ratio of longest nuclear axis to shortest nuclear axis (D/d) was significantly less in secretory than proliferative and hyperplastic endometriia. Secretory endometria also have significantly lower mean values of shape factor and significantly higher mean values of contour index than proliferative and secretory endometria. 67% of hyperplastic endometria show D-score values < 0. it seems feasible to estimate D-score for suspected EIN lesions using a semi-automated workstation based on the simple stereologic and morphometric principles described in this study, preferably, if fortified by a future comparative study in which a reference method such as the QProdit system is used.

Results of resource hydroacoustic surveys of the Baikal omul in the fishing waters of Lake Baikal in the spring-summer period of 2022

The purpose of the work carried out is to quantify the abundance of the Baikal omul within the four fishing areas of Lake Baikal (Selenginsky shallow water, Northern Baikal, the Small Sea, Barguzin Bay), to build maps of the spatial distribution of fish concentrations in the surveyed waters.The data collection and processing method is based on hydroacoustic survey, during which echo signals are recorded in the vertical direction along the route of the ship along a pre-planned transects. To calculate the values of surface densities along the survey transects, the echo integration method was used. When calculating surface density values, data from control catches are used. The Kriging geostatistical interpolator was used to numerically estimate the stocks of omul and its distribution within the surveyed water areas.New data have showed that in the main fishing area of Lake Baikal, the Selenginsky shallow water, there was a high abundance of juvenile omul, less than 22 cm in size of the 2018 generation and younger. In the areas of the Small Sea and the Barguzin Bay, no significant accumulations of fish were recorded. In Northern Baikal, the abundance and biomass of the omul was comparable to the results of 2021.The practical significance of the research results is the quantitative assessment of the omul stocks and its distribution in the fishing areas of Lake Baikal in order to predict its stocks.

Magnetophoresis in Centrifugal Microfluidics at Continuous Rotation for Nucleic Acid Extraction.

Centrifugal microfluidics enables fully automated molecular diagnostics at the point-of-need. However, the integration of solid-phase nucleic acid extraction remains a challenge. Under this scope, we developed the magnetophoresis under continuous rotation for magnetic bead-based nucleic acid extraction. Four stationary permanent magnets are arranged above a cartridge, creating a magnetic field that enables the beads to be transported between the chambers of the extraction module under continuous rotation. The centrifugal force is maintained to avoid uncontrolled spreading of liquids. We concluded that below a frequency of 5 Hz, magnetic beads move radially inwards. In support of magnetophoresis, bead inertia and passive geometrical design features allow to control the azimuthal bead movement between chambers. We then demonstrated ferrimagnetic bead transfer in liquids with broad range of surface tension and density values. Furthermore, we extracted nucleic acids from lysed Anopheles gambiae mosquitoes reaching comparable results of eluate purity (LabDisk: A260/A280 = 1.6 ± 0.04; Reference: 1.8 ± 0.17), and RT-PCR of extracted RNA (LabDisk: Ct = 17.9 ± 1.6; Reference: Ct = 19.3 ± 1.7). Conclusively, magnetophoresis at continuous rotation enables easy cartridge integration and nucleic acid extraction at the point-of-need with high yield and purity.

Magnetised winds in transition discs

Context. Protoplanetary discs are cold, dense, and weakly ionised environments that witness planetary formation. Among these discs, transition discs (TDs) are characterised by a wide cavity (up to tens of au) in the dust and gas distribution. Despite this lack of material, a considerable fraction of TDs are still strongly accreting onto their central star, possibly indicating that a mechanism is driving fast accretion in TD cavities. Aims. The presence of radially extended ‘dead zones’ in protoplanetary discs has recently revived interest in magnetised disc winds (MDWs), where accretion is driven by a large magnetic field extracting angular momentum from the disc. We propose that TDs could be subject to similar disc winds, and that these could naturally explain the fast-accreting and long-lived cavities inferred in TDs. Methods. We present the results of the first 2.5D global numerical simulations of TDs harbouring MDWs using the PLUTO code. We imposed a cavity in the gas distribution with various density contrasts, and considered a power-law distribution for the large-scale magnetic field strength. We assume the disc is weakly ionised and is therefore subject to ambipolar diffusion, as expected in this range of densities and temperatures. Results. We find that our simulated TDs always reach a steady state with an inner cavity and an outer ‘standard’ disc. These models also maintain an approximately constant accretion rate through the entire structure, reaching 10−7 M⊚ yr−1 for typical surface density values. The MDW launched from the cavity is more magnetised and has a significantly larger lever arm (up to 10) than the MDW launched from the outer disc. The material in the cavity is accreted at sonic velocities, and the cavity itself is rotating at 70% of the Keplerian velocity due to the efficient magnetic braking imposed by the MDW. Overall, our cavity matches the dynamical properties of an inner jet emitting disc (JED) and of magnetically arrested discs (MADs) in black-hole physics. Finally, we observe that the cavity is subject to recurring accretion bursts that may be driven by a magnetic Rayleigh-Taylor instability of the cavity edge. Conclusions. Some strongly accreting TDs could be the result of magnetised wind sculpting protoplanetary discs. Kinematic diagnostics of the disc or the wind (orbital velocity, wind speeds, accretion velocities) could disentangle classic photo-evaporation from MDW models.

Analysis of Seal Face Formation Parameters using Powder Metallurgy Technology with Taguchi Method and Gray Relational Analysis

The seal face is the main component of a mechanical seal to prevent leakage in a system with fluid flow. Seal face manufacture is generally produced by the material removal process, which causes some raw material waste. Powder metallurgy is the process of manufacturing products from metal powders with raw material efficiency of up to 97%. This study discusses the relationship between the manufacturing process parameters of seal face with SiC material through a powder metallurgy process as a substitute for manufacturing by material removal. The approach used in this research was the design of experiments with the Taguchi method and the technique of Gray Relational Analysis. Process parameters controlled were compaction pressure (CF), compaction time (CH), sintering temperature (ST), and sintering time (SH). Responses were measured in the form of surface hardness (HV) and density. The combination of process parameters that produces the optimum response is CF = 408 N/mm 2 (level 3), CH = 2 min (level 1) ST = 1050°C (level 3), SH = 120 min (level 2) with contribution of process parameters CF = 38.06%, CH = 2.53%, ST = 49.50%, and SH = 9.91%. The optimum surface hardness and density values were 513.03 HV and 3.04 gr/mm 3 .

Thermal and aerodynamic parameters radiation chambers of the hydrocarbon pyrolysis furnace

THE PURPOSE. To carry out mathematical modeling of interrelated physicochemical processes in radiation chambers of tubular furnaces of pyrolysis of hydrocarbons. Perform numerical calculations of heat and mass transfer in the furnace furnace chamber with a multi-tiered arrangement of wall burners on the side lined walls.METHODS. Using our own package of applied programs based on the numerical solution of a system of differential equations of energy conservation and equations of radiation gas dynamics, the fields of velocities and temperatures of natural gas combustion products in the radiation chamber of a hydrocarbon pyrolysis tubular furnace are calculated. Interrelated processes of natural gas combustion, radiant-convective heat transfer, and turbulent flow of flue gases take place in the radiation chamber. These processes are modeled by two-dimensional equations of the combustion model, energy transfer by radiation, and equations of motion. In the side walls of the radiation chamber on both sides in eight horizontal tiers there are wall burners in the amount of 128 pieces. Combustion products emerging from the nozzles of these burners create complex velocity and temperature fields in the chamber volume. Due to the radiation of flue gases, the smallest soot particles and hot lined walls of the radiation chamber, heat flows are formed to the tubular screen, where hydrocarbons are pyrolyzed to produce ethylene.RESULTS. As a result of calculations, the velocity fields, the temperature in the volume of the radiation chamber and the concentration of the main components of the combustion products were obtained. Local values of surface densities of radiant heat fluxes to reaction pipes for methane and propane pyrolysis furnaces are calculated. Comparisons of some of the results obtained with the readings of the devices of existing technological installations are carried out.CONCLUSION. Calculations show that the developed software package makes it possible to obtain realistic values of local velocities and temperatures in the radiation chambers of tube furnaces, surface densities of convective and radiant heat fluxes to boundary surfaces, and other thermal and gas-dynamic parameters in the furnace volume. With a multi-row arrangement of a large number of wall burners of low thermal power, a complex field of temperature and velocities of combustion products in the furnace volume is formed on the side walls of the radiation chamber of the furnace. At the same time, this arrangement of the burners ensures a fairly uniform distribution of heat flows over the surface of the tubular screen of the hydrocarbon pyrolysis furnace.

Antibacterial, optical, and microstructural properties investigations of Ag-doped TiO2 and TiO2/PVA nanocomposite powders

This research aims to investigate the microstructural, optical, and antibacterial properties of silver (Ag) doped titanium dioxide (TiO2) and titanium dioxide - polyvinyl alcohol (TiO2/PVA) nanocomposite powders synthesized by the sol-gel method. The powder state characterization of the nanocomposite powders was performed with SEM, EDS, XRD, laser particle size, specific surface area, density measurements, UV-vis analysis, and antibacterial tests. SEM examinations demonstrated that titanium dioxide nanoparticles synthesized using PVA dopant have relatively spherical morphology. It detected that pure, Ag-doped TiO2 and Ag-doped TiO2/PVA nanocomposite powders are in an anatase phase by XRD microanalysis. The existence of silver in the nanocomposite powders was detected by EDS analysis, XRD, and UV-vis in peak shifts. The silver and polymer dopings were decreased surface area and density values for the TiO2 system. The addition of Ag to the nanocomposite powders significantly improved the antibacterial properties of the synthesized TiO2 and TiO2/PVA nanocomposite powders against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). However, it determined that the antibacterial activity effect was little on E. coli compared to S. aureus.

Effect of Inter-Fragmentary Gap Size on Neovascularization During Bone Healing: A Micro-CT Imaging Study.

Introduction: Neovascularization of the fracture site is of great importance for bone healing and could be influenced by local mechanical environment such as fixation stability and inter-fragmentary gap size. This study aims to reconstruct the neovascularization of the fracture site and explore the effect of inter-fragmentary gap size on the spatiotemporal structure of vascularity during bone healing. Methods: Osteotomy was performed on 36 Sprague–Dawley (SD) rats on the right tibial diaphysis, and the fracture was given stable fixation with two different inter-fragmentary gap sizes. SD rats received stable fixation with either a small-sized inter-fragmentary gap (FSF1, 1 mm, n = 18) or a large-sized one (FSF3, 3 mm, n = 18). The left hind limbs were treated as the control group (CON). The animals were killed at different time points (2, 4, and 6 weeks postoperatively, n = 6, respectively) for vascular perfusion and micro-CT imaging. Results: (a) At week 2 and 4, FSF1 group showed significantly higher vessel volume ratio (VV/TV) and vessel surface density (VS/TV) values than both CON and FSF3 group; there was no significant difference in either VV/TV or VS/TV values between CON and FSF3 groups. (b) At week 6, both FSF1 and FSF3 groups showed significantly higher VV/TV and VS/TV values than CON group; FSF3 group had a significantly higher VV/TV value than FSF1 group. Conclusion: Different inter-fragmentary gap sizes greatly affect the timing of angiogenesis at the fracture site. Stable fixation with a small inter-fragmentary gap (1 mm) benefits neovascularization at the early stages during bone healing and reconstruction, while stable fixation with a large inter-fragmentary gap (3 mm) delays the occurrence of angiogenesis to a later phase.

Acoustic Insulation Mechanism of Membrane-Type Acoustic Metamaterials Loaded with Arbitrarily Shaped Mass Blocks of Variable Surface Density.

Membrane-type acoustic metamaterials (MAMs) have recently received widespread attention due to their good low-frequency sound-transmission-loss (STL) performance. A fast prediction method for the STL of rectangular membranes loaded with masses of arbitrary shapes and surface density values is proposed as a semi-analytical model for calculating the STL of membrane-type acoustic metamaterials. Through conformal mapping theory, the mass blocks of arbitrary shapes were transformed into regular shapes, which simplified the calculation model of acoustic propagation loss prediction, and the prediction results were verified by finite element simulations. The results show that the change in mass surface density was closely related to the size and frequency distribution of STL. The influence of the mass center on the STL and characteristic frequency of the film metamaterial is discussed.

Modification of Canola Oil Physicochemical Properties by Hexane and Ethanol with Regards of Its Application in Diesel Engine

A mixture of canola oil (Co), n-hexane (Hex), and ethyl alcohol (Et) was proposed as a new energy material for powering diesel engines. For this purpose, surface tension, density, and viscosity measurements, as well as engine tests, were performed for 88%Co10%Hex2%Et and 83%Co15%Hex2%Et mixtures at 20 °C. The adsorption and volumetric properties of these mixtures were compared to those of individual mixture components, as well as diesel fuel (Df) and oleic, linoleic, α-linolenic, palmitic, and stearic acids. It was revealed that the values of surface tension, viscosity, and density of Co were higher than those of the Co components. The addition of 10% Hex and 2% Et to Co caused a more than twofold decrease in its viscosity, while the addition of 15% Hex and 2% Et caused a more than fourfold reduction of Co viscosity. In addition, a mixture of Co with 2% Et and 10% Hex had a density similar to that of Df. In turn, theoretical calculations showed that the addition of n-hexane and ethanol to canola oil only slightly changed its heat of combustion. Engine tests were carried out at fixed engine rotational speeds, with a direct gearbox ratio (4th gear). The quick-changing parameters of the combustion process were registered using an AVL Indimicro system. In these tests it was found that the addition of Et to the mixture of Co and Hex did not significantly shorten the auto-ignition delay, but the kinetic phase during combustion disappeared, which had an impact on the combustion start angle.

Effect of Al2O3 Doping on Antibacterial Activity of 45S5 Bioactive Glass

45S5 bioactive glasses (BGs) are special class of glasses that form chemical bonds with surrounding bone tissue, which is due to the dissolution behavior of these glass materials. Furthermore, BG shows an antibacterial effect since the dissolution of BG results with high aqueous pH that affect bacterial viability. In this study, the antibacterial activity of Al2O3 doped bioactive glasses (AGs) was evaluated. AGs were produced via the melt quenching method. Functional groups of glasses were evaluated with Fourier Transform Infrared (FTIR) analysis, and glassy structure was evaluated by X-ray diffraction (XRD). Specific surface area, particle size information and density of milled BG and AGs were obtained using surface area and porosity instrument, laser scattering particle size distribution analyzer and He pycnometer, respectively. Antibacterial activity of bioactive glasses was investigated on Staphylococcus aureus and Escherichia coli via Standard Colony Count Method at 50 mg/ml concentration and different time points, pH change of the media in the presence of BG and AGs at 50 mg/ml concentration was also measured at identical time points. XRD analysis revealed amorphous structure of BG and AGs. Similar specific surface area, particle size and density values were obtained for BG and produced AGs. Antibacterial test results showed that Al2O3 doped 45S5 bioactive glasses had decreased antibacterial activity compared to 45S5 bioactive glass for both bacteria studied.

DEM-based modelling framework for spray-dried powders in ceramic tiles industry. Part III: Validation procedure

This is the third and final paper in a series presenting a DEM-based modelling framework for simulating the spray-dried powder rheology in ceramic tiles industry. Part I described the characterization of the spray-dried powder. Part II detailed the implementation of a new dedicated solver for simulating demanding scenarios. In this part, the validation procedure of the framework is presented through 2 validation series: a partial mould filling and a complete mould filling equivalent to industrial filling. A pilot-scale powder feeder was built expressly for this purpose. Powder dynamics was accurately reproduced in series 1, with a maximum relative error of 10%. Surface density in the mould was adequately reproduced in series 2 (maximum absolute error < 4 kg/m2). The formation of defects is accurately predicted. Some discrepancies in the surface density values are observed. The DEM-based modelling framework proves as a valid tool to design and optimize spray-dried powder handling equipment.

Effect of Fluorescent Labels on DNA Affinity for Gold Nanoparticles.

Fluorophore (FD) labeling is widely used for detection and quantification of various compounds bound to nanocarriers. The systems, composed of gold nanoparticles (GNPs) and oligonucleotides (ONs) labeled with FDs, have wide applications. Our work was aimed at a systemic study of how FD structure (in composition of ON-FDs) influenced the efficiency of their non-covalent associates’ formation with GNPs (ON-FD/GNPs). We examined ONs of different length and nucleotide composition, and corresponding ON-FDs (FDs from a series of xanthene, polymethine dyes; dyes based on polycyclic aromatic hydrocarbons). Methods: fluorometry, dynamic light scattering, high performance liquid chromatography, gel electrophoresis, molecular modeling and methods of thermodynamic and statistical analysis. We observed significant, differing several times, changes in surface density and Langmuir constant values of ON-FDs vs. ONs, evidence for the critical significance of FD nature for binding of ON-FDs with GNPs. Surface density of ON-FD/GNPs; hydrophobicity and total charge of ON or ON-FD; and charge and surface area of FDs were revealed as key factors determining affinity (Langmuir constant) of ON or ON-FDs for GNPs. These factors compose a specific set, which makes possible the highly reliable prediction of efficiency of ONs and ON-FDs binding with GNPs. The principal possibility of creating an algorithm for predictive calculation of efficiency of ONs and GNPs interaction was demonstrated. We proposed a hypothetical model that described the mechanism of contact interaction between negatively charged nano-objects, such as citrate-stabilized GNPs, and ONs or ON-FDs.

Relationship between the coefficient of friction of additive in the bulk and chain graft surface density through a diffusion process: Erucamide–stearyl erucamide mixtures in polypropylene films

AbstractA relationship between chain graft density calculated by coarse‐grained simulation and the one obtained from experimental results is compared in the present work. Two slip additives for polypropylene films were studied, erucamide and stearyl erucamide. The diffusion equation (Fick's second law) was used to relate real‐time experimental results with coarse‐grained simulations and rendered slip additive surface density as a function of the coefficient of friction. The normalized surface density values obtained from the simulation showed a qualitative trend consistent with the experimentally observed results.