Two Contact Binaries with Mass Ratios Close to the Minimum Mass Ratio

The cutoff mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850 (hereafter J082700) and 1SWASP J132829.37+555246.1 (hereafter J132829) are both less than 0.1 (q ∼ 0.055 for J082700 and q ∼ 0.089 for J132829). J082700 is a shallow contact binary with a contact degree of ∼19%, and J132829 is a deep contact system with a fill-out factor of ∼70%. The O − C diagram analysis indicated that the two systems manifested long-term period decreases. In addition, J082700 exhibits a cyclic modulation which is more likely resulting from the Applegate mechanism. In order to explore the properties of extremely low mass ratio contact binaries (ELMRCBs), we carried out a statistical analysis on contact binaries with mass ratios of q ≲ 0.1 and discovered that the values of J spin/J orb of three systems are greater than 1/3. Two possible explanations can interpret this phenomenon. One explanation is that some physical processes, unknown to date, are not considered when Hut presented the dynamic stability criterion. The other explanation is that the dimensionless gyration radius (k) should be smaller than the value we used (k 2 = 0.06). We also found that the formation of ELMRCBs possibly has two channels. The study of evolutionary states of ELMRCBs reveals that their evolutionary states are similar with those of normal W UMa contact binaries.

Neighborhood-Based Descriptors for Porphyrin Dendrimers

The symmetry of molecular structures is captured by topological indices, which provide a mathematical vocabulary for predicting features such as boiling temperatures, viscosity, and gyration radius and are also employed in QSPR/QSAR research. Dendrimers are a brand-new type of polymer. It is characterized as a macromolecule due to its highly radiated structure, providing great water solubility and adaptability. Because of these features, dendrimers are a strong alternative for medication delivery. This article investigates some topological indices based on neighborhood degrees such as Modified Randic index, Inverse Sum Index, SK, SK1, and SK2 index for some dendrimers.

Exploring App-Based Taxi Movement Patterns from Large-Scale Geolocation Data

This study is designed to leverage ubiquitous mobile computing techniques on exploring app-based taxi movement patterns in large cities. To study patterns at different scales, we comprehensively explore both occupied and unoccupied vehicle movement characteristics through not only individual trips but also their aggregations. Moran’s I and its variations are applied to explore spatial autocorrelations among different rides. PageRank centrality is applied for a functional network representing traffic flows to discover places of interest. Gyration radius measures the scope of passenger mobility and driver passenger searching. Moreover, cumulative distribution and data visualization techniques are adopted for trip level characteristics and features analysis. The results indicate that the app-based taxi services are serving more neighborhoods other than downtown areas by taking large proportion of relatively shorter trips and contributing to net increase in total taxi ridership although net decrease in downtown areas. The spatial autocorrelations are significant not only within each service but also among services. With the smartphone-based applications, app-based taxi services are able to search passengers in a larger area and move more efficiently during both occupied and unoccupied periods. Mining from huge empty trip trajectory by app-based taxis, we also identify the existence of stationary/stops state and circulations.

Molecular Dynamics Study of the Conformation, Ion Adsorption, Diffusion and Water Structure of Soluble Polymers in Saline Solutions

Polymers have interesting physicochemical characteristics such as charge density, functionalities, and molecular weight. Such attributes are of great importance for use in industrial purposes. Understanding how these characteristics are affected is still complex, but with the help of molecular dynamics (MD) and quantum calculations (QM), it is possible to understand the behavior of polymers at the molecular level with great consistency. This study was applied to polymers derived from polyacrylamide (PAM) due to its great use in various industries. The polymers studied include hydrolyzed polyacrylamide (HPAM), poly (2-acrylamido-2-methylpropanesulfonate) (PAMPS), polyacrylic acid (PAA), polyethylene oxide polymer (PEO), and guar gum polysaccharide (GUAR). Each one has different attributes, which help in understanding the effects on the polymer and the medium in which it is applied along a broad spectrum. The results include the conformation, diffusion, ion condensation, the structure of the water around the polymer, and interatomic polymer interactions. Such characteristics are important to selecting a polymer depending on the environment in which it is found and its purpose. The effect caused by salinity is particular to each polymer, where polymers with an explicit charge or polyelectrolytes are more susceptible to changes due to salinity, increasing their coiling and reducing their mobility in solution. This naturally reduces its ability to form polymeric bridges due to having a polymer with a smaller gyration radius. In contrast, neutral polymers are less affected in their structure, making them favorable in media with high ionic charges.

The approximate calculation of the natural frequencies of a Stockbridge type vibration damper and analysis of natural frequencies' sensitivity to the structural parameters

Vibration damper is widely used in overhead transmission lines to alleviate aeolian vibration. Its natural frequencies are important parameters for a vibration damper. In this paper, the approximate calculation formulas of natural frequencies of the one-side subsystem of a Stockbridge type vibration damper were derived and the design sensitivity analysis of the natural frequencies was studied using partial differential equations with respect to each concerned parameter including the length of the steel strand, the mass of the counterweight, the eccentric distance, and the radius of gyration of the counterweight. Through a case study that considered a variation of up to ±30 % in the values of the design parameters, the exact calculation and approximate calculation results of the natural frequencies were analysed, and the sensitivity of the vibration damper's natural frequencies to the design parameters was studied. The results show that, within the range of the parameters used in this study, the approximately calculated first-order frequency is lower than the exact values, whereas the approximately calculated second-order frequency is larger than the exact values. The sensitivity analysis indicates that the first-order frequency is highly sensitive to the steel strand's length, whereas it is moderately sensitive to the counterweight's mass and slightly sensitive to the eccentric distance and the gyration radius of the counterweight; the second-order frequency is highly sensitive to the steel strand's length and the gyration radius of the counterweight, moderately sensitive to the counterweight's mass, and slightly sensitive to the eccentric distance. It will provide theoretical guidance and approximate analysis method in engineering for the design of the vibration damper.

Interfacial Engineering of Smart Polymer Self-Assembly Using Doped-Nanostructures for Constructing Stable Nano-Carriers

Nowadays, nanotechnology has been developed in various fields of treatment, including cancer treatment. Since the prevalence of different types of cancer has risen, and currently available cancer treatments such as chemotherapy and radiotherapy may cause serious side effects. In this regard, researchers have made considerable efforts to encourage the creation and make strides in treating this deadly disease. Meanwhile, nanotechnology has become widespread, and various nanomaterials, including nanoparticles, have been extensively used to transfer the drug to the targeted sites. Recently, many drug delivery systems have been developed based on nanoparticles, and various substances have been employed as drug stimulants or enhancers to improve the treatment effectiveness, stability, and safety of anticancer drugs. In this paper, the drug delivery capability of three new categories of carbon nanoparticles (i.e., Fullerenes, nanosheets, and Carbon Nano Tubes (CNTs)) was investigated by Molecular Dynamics (MD) simulation. Energy, Gyration Radius (Rg), Hydrogen bond (H-Bond), Radial Distribution Function (RDF), and Solvent Accessible Surface Area (SASA) analyses have been used to compare the studied nanoparticles. The Boron Carbon Nitride (BCN) nanosheet simulation exhibited the lowest drug particle Contact Area, the highest RDF, the most inferior reduction in the Rg, the highest number of H-Bonds, and the highest drug adsorption energy. Thus, BCN nanosheet was introduced as the best nanoparticle for drug delivery purposes.

Molecular dynamics study of alloying process of Cu–Au nanoparticles with different heating rates

In this paper, molecular dynamics (MD) simulation is utilized for the investigation of impact of heating rates on Au and Cu nanoparticles alloying process. Aggregation of contacted nanoparticles experiences three stages due to the contacting, while the alloying process can be distinguished into five regimes because of the contacting and melting. Different heating rates result in different contact temperatures. The decrease of the potential energy can be observed when the temperature reaches the melting temperature. When the temperature reaches the melting point, shrinkage ratio and relative gyration radius have drastic changes during the alloying process. It is shown that heating rates have an apparent effect on the shrinkage ratio and the relative gyration radius during the fusing process, and the shrinkage ratio and the relative gyration radius of Au and Cu alloying systems with lower heating rates have relative larger increasing ratio and decreasing ratio, respectively.

Genetic and Environmental Variation in Starch Content, Starch Granule Distribution and Starch Polymer Molecular Characteristics of French Bread Wheat

This study investigates genetic and environmental variation in starch content and characteristics of 14 French bread cultivars. Understanding the impact of these factors on wheat quality is important for processors and especially bakers to maintain and meet the requirements of industrial specifications. Different traits were evaluated: starch content, distribution of starch granules, percentage of amylose and amylopectin and their molecular characteristics (weight-average molar mass, number-average molar mass, polydispersity and gyration radius). Genetic, environment and their interaction had significant effects on all parameters. The relative magnitude of variance attributed to growth conditions, for most traits, was substantially higher (21% to 95%) than that attributed to either genotype (2% to 73%) or G × E interaction (2% to 17%). The largest environmental contribution (95%) to total variance was found for starch dispersity. The highest genetic influence was found for the percentage of A-type starch granules. G × E interaction had relatively little influence (≈7%) on total phenotypic variance. All molecular characteristics were much more influenced by environment than the respective percentages of amylose and amylopectin were. This huge difference in variance between factors obviously revealed the importance of the effect of growing conditions on characteristics of cultivars.

Loading and Release of Anti -Cancer Drugs Using Simultaneous pH and Temperature Responsive Nanohybrid

BackgroundTodays, drug nanocarrier development and improving its biophysical properties is one of the updated and intended of nano-biopharmaceutical science researches. Single-walled carbon nanotubes (SWCNT), as a typical carbon structure based nanocarrier, but have some obstacles in drug delivery mechanisms. In that current study, the penetration, loading, and release of Doxorubicin and Paclitaxel, as two anticancer agents, were investigated using a novel modified and functionalized SWCNT.ResultsThis study was carried out using molecular dynamics simulation based on a dual-responsive smart biomaterial. At the in-silico study, Interaction energies between drugs and carriers, numbers of hydrogen bonds, diffusion coefficient, and gyration radius were investigated. The kinetic analysis of drug adsorption and release revealed that, fascinatingly, drug loading and drug release are selective at physiological and cancerous acidic pH, respectively. Interaction of Dimethyl acryl amid-trimethyl chitosan, as a biodegradable and biocompatible hydrogel, with SWCNT indicated that degradation reaction in acidic condition destructs the polymer, which leads to a smart release in cancerous tissue at specific pH. Moreover, it resolves hydrophilicity, optimum nanoparticle size, cell membrane penetration, and cell toxicity concerns.ConclusionsThe simulation results indicated a marvelous role of dimethyl acryl amide-trimethyl chitosan in the adsorption and release of anticancer drugs in normal and neoplastic tissue. The interaction of trimethyl chitosan also improves biocompatibility as well as biodegradability of the carrier. Overall, that novel drug carrier can be a virtuous nanoparticle for loading, transporting, and releasing the anticancer drugs.