Structural analysis of the comet 45P/Honda based on isophote modeling

Abstract The work focuses on using the isophote method to construct a 45P/Honda comet model. At the same time, important problems were solved for modeling the physical surface of a comet and studying the structure of the cometary nucleus. This is due to the fact that, on the basis of modern studies of meteoroids, complex internal processes and dynamic phenomena on their surface have been discovered. The study of comet nuclei is of great importance, since, according to the theory of their formation, they were formed from the matter of the protoplanetary disk. Thus, modeling and analysis of the structure of various comets make it possible to create a more accurate theory of their evolution. This made it possible to evaluate the structural parameters more accurately and reliably. This allowed for the evaluation of the structural parameters more accurately and reliably. Isophotes of the nucleus, coma and tail of comet 45P/Honda were determined. Depending on the point where the comet is located on the trajectory of its orbit, one can see structural changes in the comet’s brightness from the nucleus to the peripheral region. Near the cometary nucleus, the isophotes are circular in shape. If in the center of the model the isophotes have a shape close to narrow rings, then elongations in the direction of the cometary tail and thickening of their structure appear towards the peripheral regions. Large and small tail rays can be distinguished, and the nucleus is well marked. In the future, the author’s method for modeling isophotes, developed in this work, will allow studying the structure of various cometary objects, and, based on the results, determine the degree of comet activity. On the other hand, about the development of the theory of dynamic processes and the evolution of the Solar system, one can use the data on changes in cometary activity in the process of its movement around the Sun.

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Models of comets with strongly variable nongravitational effects

International Astronomical Union Colloquium ◽

10.1017/s0252921100031705 ◽

1999 ◽

Vol 173 ◽

pp. 381-387

Author(s):

M. Królikowska ◽

G. Sitarski ◽

S. Szutowicz

Keyword(s):

Cometary Nucleus ◽

Spin Axis ◽

Reactive Force ◽

Orbital Elements ◽

Cometary Nuclei ◽

Short Period ◽

Basic Parameters ◽

Polar Radius ◽

Cometary Activity ◽

Nongravitational Effects

AbstractThe nongravitational motion of five “erratic” short-period comets is studied on the basis of published astrometric observations. We present the precession models which successfully link all the observed apparitions of the comets: 21P/Giacobini-Zinner, 31P/Schwassmann-Wachmann 2, 32P/Comas Solá, 37P/Forbes, and 43P/Wolf-Harrington. We used the Sekanina's forced precession model of the rotating cometary nucleus to include the nongravitational terms into equations of the comet's motion. Values of six basic parameters (four connected with the rotating comet nucleus and two describing the precession of spin-axis of the nucleus) have been determined along the orbital elements from positional observations of the comets. The solutions were derived with additional assumptions which introduce instantaneous changes of modulus of reactive force,Aand of maximum of cometary activity with respect to perihelion time. The present precession models impose some contraints on sizes and rotational periods of cometary nuclei. According to our solutions the nucleus of 21P/Giacobini-Zinner with oblateness along the spin-axis of about 0.32 (equatorial to polar radius of 1.46) is the most oblate among five investigated comets.

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Quantitative relations between structure and antiinflammatory activity of aryloxoalkanoic acids

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19881862 ◽

1988 ◽

Vol 53 (8) ◽

pp. 1862-1872 ◽

Cited By ~ 11

Author(s):

Miroslav Kuchař ◽

Eva Maturová ◽

Bohumila Brunová ◽

Jaroslava Grimová ◽

Hana Tomková ◽

...

Keyword(s):

Regression Analysis ◽

Structural Changes ◽

Antiinflammatory Activity ◽

Structural Parameters ◽

Considerable Effect ◽

Antiinflammatory Effect ◽

Prolonged Action ◽

Preclinical Development ◽

Indicator Variables ◽

Inhibitory Activities

The antiinflammatory effect of a series of aryloxoalkanoic acids II and of their biphenyl derivatives III was examined by measuring the inhibition of the development of carageenan- and adjuvant-induced edemas. The quantitative relations between the antiinflammatory effect and physicochemical and structural parameters of the compounds tested were evaluated. The equations obtained by the method of regression analysis showed a significant linear dependence of both inhibitory activities on the lipophilicity of the compounds and a considerable effect of some structural changes as expressed by indicator variables. The antiinflammatory effect is especially enhanced in both tests by the presence of a cyclic substituent at the aromatic ring. The high antiinflammatory effect of biphenylyl derivatives III is paralleled by their prolonged action. The prolongation of the effect is most likely a result of a suitable biotransformation of acid III to an efficient metabolite. The structural requirements which resulted from both the regression analysis and from the hypothesis of biotransformation of acids III were utilized in the synthesis of suitably substituted biphenylyloxoalkanoic acids. By this approach derivatives IIIe-i were obtained some of which showed a high antiinflammatory and also protracted effect. 4-(2',4'-Difluorbiphenylyl)-4-oxo-2-methylbutanoic acid (VÚFB-16 066, Flobufen) was chosen for further preclinical development.

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Changes of Selected Structural and Mechanical Properties of the Strzelin Granites As Induced By Thermal Loads / Wpływ Obciążeń Termicznych Na Zmiany Niektórych Strukturalnych I Mechanicznych Właściwości Granitów Strzelińskich

Archives of Mining Sciences ◽

10.2478/v10267-012-0064-8 ◽

2012 ◽

Vol 57 (4) ◽

pp. 951-974 ◽

Cited By ~ 1

Author(s):

Andrzej Nowakowski ◽

Mariusz Młynarczuk

Keyword(s):

Mechanical Properties ◽

Nuclear Waste ◽

Structural Changes ◽

Structural Parameters ◽

Total Porosity ◽

Fracture Network ◽

Qualitative Description ◽

Temperature Changes ◽

Heating And Cooling ◽

Waste Repositories

Abstract Temperature is one of the basic factors influencing physical and structural properties of rocks. A quantitative and qualitative description of this influence becomes essential in underground construction and, in particular, in the construction of various underground storage facilities, including nuclear waste repositories. The present paper discusses the effects of temperature changes on selected mechanical and structural parameters of the Strzelin granites. Its authors focused on analyzing the changes of granite properties that accompany rapid temperature changes, for temperatures lower than 573ºC, which is the value at which the β - α phase transition in quartz occurs. Some of the criteria for selecting the temperature range were the results of measurements carried out at nuclear waste repositories. It was demonstrated that, as a result of the adopted procedure of heating and cooling of samples, the examined rock starts to reveal measurable structural changes, which, in turn, induces vital changes of its selected mechanical properties. In particular, it was shown that one of the quantities describing the structure of the rock - namely, the fracture network - grew significantly. As a consequence, vital changes could be observed in the following physical quantities characterizing the rock: primary wave velocity (vp), permeability coefficient (k), total porosity (n) and fracture porosity (η), limit of compressive strength (Rσ1) and the accompanying deformation (Rε1), Young’s modulus (E), and Poisson’s ratio (ν).

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Changes in Value Orientations in Serbia, 2003–2018 . Patriarchy, Authoritarianism and Nationalism

Südosteuropa ◽

10.1515/soeu-2020-0029 ◽

2020 ◽

Vol 68 (3) ◽

pp. 408-431

Author(s):

Irena Petrović ◽

Marija Radoman

Keyword(s):

Structural Changes ◽

Empirical Studies ◽

Value Orientations ◽

The Other ◽

Social Changes ◽

Ethnic Nationalism ◽

Political Situation ◽

Other Hand ◽

The Social ◽

Private And Public

AbstractThe authors analyze the changes in value patterns—patriarchy, authoritarianism and nationalism—in Serbia in the context of the social changes that have marked the postsocialist transformation period. They focus on the extent and intensity of two sub-patterns within each of these three basic value patterns: private and public patriarchy, general and specific authoritarianism, organic (natural) and ethnic nationalism. The conclusions about changes in these value patterns are drawn on the basis of three empirical studies conducted in 2003, 2012, and 2018. They show the prevalence of private patriarchy, general authoritarianism, and organic (natural) nationalism over their counterparts. Private patriarchy has weakened, which is largely to be explained by the significant structural changes in Serbia. On the other hand, support of general authoritarianism and organic (natural) nationalism has been on the rise, which clearly mirrors the unfavorable economic and political situation in the country.

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Involvement of loop 5 lysine residues and the N-terminal β-hairpin of the ribotoxin hirsutellin A on its insecticidal activity

Biological Chemistry ◽

10.1515/hsz-2015-0261 ◽

2016 ◽

Vol 397 (2) ◽

pp. 135-145 ◽

Cited By ~ 4

Author(s):

Miriam Olombrada ◽

Lucía García-Ortega ◽

Javier Lacadena ◽

Mercedes Oñaderra ◽

José G. Gavilanes ◽

...

Keyword(s):

Active Sites ◽

Structural Changes ◽

The Other ◽

Spatial Proximity ◽

Ribonucleolytic Activity ◽

The Family ◽

Lysine Residues ◽

Hirsutella Thompsonii ◽

Close Spatial Proximity ◽

High Degree

Abstract Ribotoxins are cytotoxic members of the family of fungal extracellular ribonucleases best represented by RNase T1. They share a high degree of sequence identity and a common structural fold, including the geometric arrangement of their active sites. However, ribotoxins are larger, with a well-defined N-terminal β-hairpin, and display longer and positively charged unstructured loops. These structural differences account for their cytotoxic properties. Unexpectedly, the discovery of hirsutellin A (HtA), a ribotoxin produced by the invertebrate pathogen Hirsutella thompsonii, showed how it was possible to accommodate these features into a shorter amino acid sequence. Examination of HtA N-terminal β-hairpin reveals differences in terms of length, charge, and spatial distribution. Consequently, four different HtA mutants were prepared and characterized. One of them was the result of deleting this hairpin [Δ(8-15)] while the other three affected single Lys residues in its close spatial proximity (K115E, K118E, and K123E). The results obtained support the general conclusion that HtA active site would show a high degree of plasticity, being able to accommodate electrostatic and structural changes not suitable for the other previously known larger ribotoxins, as the variants described here only presented small differences in terms of ribonucleolytic activity and cytotoxicity against cultured insect cells.

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Relative Earnings and Manpower Allocation in Developing Economies

The Pakistan Development Review ◽

10.30541/v9i1pp.14-34 ◽

1969 ◽

Vol 9 (1) ◽

pp. 14-34 ◽

Cited By ~ 1

Author(s):

Lloyd G. Reynolds

Keyword(s):

Economic Growth ◽

Subject Matter ◽

Structural Changes ◽

Developing Economies ◽

Developed Countries ◽

The Other ◽

Labour Economics ◽

Economic Behaviour ◽

Agriculture Industry ◽

Starting Point

The less developed countries (LDC) present two kinds of challenge to economists. First, they invite us to develop hypotheses about how economic growth begins and about structural changes during the early decades of growth. Second, they provide a fresh terrain on which specialists in particular subject-matter areas can test accepted notions about economic behaviour. For investigations in labour economics, the structure of earnings provides a convenient starting point. (It is best to say "earnings" rather than "wages" because most workers in the LDC's are self-emplqyed.) Analysis of earnings requires an examination of manpower supplies and requirements. This leads into the economics of agriculture, industry, government, and other labour demanding sectors on one side, and into a study of education and other skill-producing agencies, on the other. Thus by starting with the earnings structure, one is led rather directly into the heart of the economy.

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Physical Properties and Non-Isothermal Crystallisation Kinetics of Primary Mechanically Recycled Poly(l-lactic acid) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Polymers ◽

10.3390/polym13193396 ◽

2021 ◽

Vol 13 (19) ◽

pp. 3396

Author(s):

Luboš Běhálek ◽

Jan Novák ◽

Pavel Brdlík ◽

Martin Borůvka ◽

Jiří Habr ◽

...

Keyword(s):

Lactic Acid ◽

Physical Properties ◽

Structural Changes ◽

The Other ◽

Half Time ◽

Crystallisation Kinetics ◽

Isothermal Crystallisation ◽

Melt Crystallisation ◽

Kinetics Of ◽

Crystallisation Rate

The physical properties and non-isothermal melt- and cold-crystallisation kinetics of poly (l-lactic acid) (PLLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biobased polymers reprocessed by mechanical milling of moulded specimens and followed injection moulding with up to seven recycling cycles are investigated. Non-isothermal crystallisation kinetics are evaluated by the half-time of crystallisation and a procedure based on the mathematical treatment of DSC cumulative crystallisation curves at their inflection point (Kratochvil-Kelnar method). Thermomechanical recycling of PLLA raised structural changes that resulted in an increase in melt flow properties by up to six times, a decrease in the thermal stability by up to 80 °C, a reduction in the melt half-time crystallisation by up to about 40%, an increase in the melt crystallisation start temperature, and an increase in the maximum melt crystallisation rate (up to 2.7 times). Furthermore, reprocessing after the first recycling cycle caused the elimination of cold crystallisation when cooling at a slow rate. These structural changes also lowered the cold crystallisation temperature without impacting the maximum cold crystallisation rate. The structural changes of reprocessed PHBV had no significant effect on the non-isothermal crystallisation kinetics of this material. Additionally, the thermomechanical behaviour of reprocessed PHBV indicates that the technological waste of this biopolymer is suitable for recycling as a reusable additive to the virgin polymer matrix. In the case of reprocessed PLLA, on the other hand, a significant decrease in tensile and flexural strength (by 22% and 46%, respectively) was detected, which reflected changes within the biobased polymer structure. Apart from the elastic modulus, all the other thermomechanical properties of PLLA dropped down with an increasing level of recycling.

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Development of breathable Janus superhydrophobic polyester fabrics using alkaline hydrolysis and blade coating

Textile Research Journal ◽

10.1177/0040517518760750 ◽

2018 ◽

Vol 89 (6) ◽

pp. 959-974 ◽

Cited By ~ 3

Author(s):

Seonyoung Youn ◽

Chung Hee Park

Keyword(s):

Mechanical Properties ◽

Alkaline Hydrolysis ◽

Structural Changes ◽

Treatment Time ◽

Volume Ratio ◽

Alkaline Treatment ◽

The Other ◽

Solution Temperature ◽

Optimal Conditions ◽

Wetting Properties

Alkaline hydrolysis is a common finishing method that is used to give polyester (polyethylene terephthalate, PET) a more natural touch and improved luster via chemical or physical changes in the fibers. However, its potential as a tool for surface modification in the development of single-sided superhydrophobic materials has not been studied yet. In this research, Janus superhydrophobic PET fabrics with asymmetric wetting properties (one side of the PET surface was rendered superhydrophobic while the other side was simply hydrophobic) were fabricated in two steps. Fine roughness was first achieved on the surface of PET fabrics by alkaline hydrolysis. Subsequently, optimized foam-coating emulsions were applied on only one surface of the alkaline-hydrolyzed PET. Alkaline treatment time, solution temperature, and viscosity of the foam-coating emulsions were varied to find optimal conditions in terms of structural changes, mechanical properties, superhydrophobicity, and absorption ability. The specimen treated with an aqueous solution of 8% sodium hydroxide at 70℃ for 60 min and coated with the mixture of the fluoro-emulsion and thickener in the volume ratio of 40:2 was determined to be the optimal conditions for the Janus superhydrophobic property. This sample showed a contact angle of 162.8° and a shedding angle of 5.6° on one side, whereas it completely permitted the percolation of water drops on the other side within 109 s. The mechanical properties of the developed Janus PET under the optimal conditions did not decrease significantly; its weight and tensile strength were found to have decreased by 3.3% and 19.2%, respectively. Furthermore, the single-sided superhydrophobic specimen demonstrated higher moisture transmissibility than the double-sided coated PET under the same alkaline treatment conditions. The method developed herein eliminates the requirement for an additional process to deliver nanoscale surface roughness and has the potential to produce waterproof–breathable PET fabrics for outdoor clothing.

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Motif Analysis and the Periodic Structural Changes in an Organizational Email-Based Social Network

Virtual Communities ◽

10.4018/978-1-60960-100-3.ch121 ◽

2011 ◽

pp. 292-302

Author(s):

Krzysztof Juszczyszyn ◽

Katarzyna Musial

Keyword(s):

Social Networks ◽

Social Network ◽

Network Topology ◽

Structural Changes ◽

Structural Parameters ◽

Local Network ◽

Network Motifs ◽

Motif Analysis ◽

University Of Technology ◽

E Mail

Network motifs are small subgraphs that reflect local network topology and were shown to be useful for creating profiles that reveal several properties of the network. In this work the motif analysis of the e-mail network of the Wroclaw University of Technology, consisting of over 4000 nodes was conducted. Temporal changes in the network structure during the period of 20 months were analysed and the correlations between global structural parameters of the network and motif distribution were found. These results are to be used in the development of methods dedicated for fast estimating of the properties of complex internet-based social networks.

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A comparison between the two lobes of comet 67P/Churyumov–Gerasimenko based on D/H ratios in H2O measured with the Rosetta/ROSINA DFMS

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2482 ◽

2019 ◽

Vol 489 (4) ◽

pp. 4734-4740 ◽

Cited By ~ 4

Author(s):

Isaac R H G Schroeder ◽

Kathrin Altwegg ◽

Hans Balsiger ◽

Jean-Jacques Berthelier ◽

Michael R Combi ◽

...

Keyword(s):

Mass Spectrometer ◽

European Space Agency ◽

Cometary Nucleus ◽

The Other ◽

Appreciable Difference ◽

Space Agency ◽

Close Proximity ◽

Double Focusing ◽

Comet 67P

ABSTRACT The nucleus of the Jupiter-family comet 67P/Churyumov–Gerasimenko was discovered to be bi-lobate in shape when the European Space Agency spacecraft Rosetta first approached it in 2014 July. The bi-lobate structure of the cometary nucleus has led to much discussion regarding the possible manner of its formation and on how the composition of each lobe might compare with that of the other. During its two-year-long mission from 2014 to 2016, Rosetta remained in close proximity to 67P/Churyumov–Gerasimenko, studying its coma and nucleus in situ. Based on lobe-specific measurements of HDO and H2O performed with the ROSINA Double Focusing Mass Spectrometer (DFMS) on board Rosetta, the deuterium-to-hydrogen (D/H) ratios in water from the two lobes can be compared. No appreciable difference was observed, suggesting that both lobes formed in the same region and are homogeneous in their D/H ratios.

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