scholarly journals Sublimation of organic-rich comet analog materials and their relevance in fracture formation

2021 ◽  
Vol 653 ◽  
pp. A153
Author(s):  
David Haack ◽  
Christopher Kreuzig ◽  
Bastian Gundlach ◽  
Jürgen Blum ◽  
Katharina Otto
Keyword(s):  
Morphological Evolution ◽  
Sample Surface ◽  
Sample Volume ◽  
Spherical Particles ◽  
Vacuum Sublimation ◽  
Organic Components ◽  
Fracture Formation ◽  
The Stability ◽  
External Light Source ◽  
Adhesive Effect

Aims. The morphology of cometary nuclei is the result of an ongoing evolution and can provide valuable information to constrain the composition of comets. In our laboratory experiments we investigated the morphological evolution of comet analog materials, which consist of volatile, dust, and organic components. The laboratory results are aimed to help understand the evolution of cometary surfaces. Methods. We used spherical particles of fly ash and mixtures of ice, glycine, and sodium acetate as analog materials in different mass ratios to reproduce observed cometary morphologies. The cohesive and gravitational properties in the laboratory are scaled to cometary conditions to draw meaningful conclusions from the experimental results. The samples were placed in a vacuum sublimation chamber, cooled down to below 150 K, and were insolated with an external light source. To analyze the morphology of the samples, a camera was used to monitor the alterations of the surface. Results. Organic components in volatile-rich samples can have a distinct adhesive effect after the volatiles sublimate. During the sublimation process the sample volume decreases and fractures form on the sample surface. Due to the stability of the remaining volatile-depleted material, significant cliff collapses or ejected particles were not observed in the laboratory.

scholarly journals An integral equation formulation of the N-body dielectric spheres problem. Part 1: Numerical analysis

2020 ◽  
Author(s):  
Muhammad Hassan ◽  
Benjamin Stamm
Keyword(s):  
Integral Equation ◽  
Numerical Analysis ◽  
Error Analysis ◽  
Convergence Rates ◽  
A Priori ◽  
Approximation Error ◽  
Spherical Particles ◽  
Integral Equation Formulation ◽  
Dielectric Spheres ◽  
The Stability

In this article, we analyse an integral equation of the second kind that represents the solution of N interacting dielectric spherical particles undergoing mutual polarisation. A traditional analysis can not quantify the scaling of the stability constants- and thus the approximation error- with respect to the number N of involved dielectric spheres. We develop a new a priori error analysis that demonstrates N-independent stability of the continuous and discrete formulations of the integral equation. Consequently, we obtain convergence rates that are independent of N.

scholarly journals Laws and Trends of the Evolution of Traditional Villages in Plane Pattern

2020 ◽  
Vol 12 (7) ◽  
pp. 3005
Author(s):  
Xi Yang ◽  
Ke Song ◽  
Fuan Pu
Keyword(s):  
Spatial Data ◽  
Nearest Neighbor ◽  
Morphological Evolution ◽  
Temporal Analysis ◽  
Mean Value ◽  
Significant Shift ◽  
Spatial Processes ◽  
Common Mean ◽  
Multi Temporal ◽  
The Stability

This study collected and analyzed dynamic spatial data of eight traditional villages scattered in different regions of China. A multi-temporal analysis of morphological metrics of spatial patterns and a regression analysis of the morphological evolution were used to analyze and contrast the historical spatial processes of different villages. These were then compared using patch texture and rural macro-morphology perspectives. This led to an assessment of the general laws and trends associated with rural spatial processes. (1) There has been a significant shift in the stability of rural spatial development since the founding of the People’s Republic of China (PRC). (2) Most small and medium-sized villages have maintained a relatively stable spatial texture, while large villages have changed significantly. (3) The mean and variance of the patch area, and the Euclidean nearest-neighbor distance, are correlated in some cases. (4) The mode of rural expansion may be relevant to limitations in the total area of growth. (5) The fractal dimension of the rural macro-morphology may follow a morphological order of oscillation around the equilibrium level. (6) The common mean value of the projected area of rural building patches is expected to be 100 m2.

scholarly journals PREPARATION AND CHARACTERIZATION OF GLIADIN NANOPARTICLES FOR BRAIN DRUG DELIVERY

2018 ◽  
Vol 11 (7) ◽  
pp. 345
Author(s):  
Ankit Dubey Naveneet Dubey ◽  
Suman Ramteke ◽  
Deepti Jain
Keyword(s):  
Controlled Release ◽  
Nasal Spray ◽  
Phosphate Buffer ◽  
Spherical Particles ◽  
Brain Targeting ◽  
Brain Drug Delivery ◽  
The Stability ◽  
Nano Size

Objectives: The aim of the present work is to prepare and evaluate nasal controlled release gliadin nanoparticles of sumatriptan for antimigraine activity to improve patients’ compliance by simplifying its administration, improving its therapeutic effect, and reducing its dose-related side effects through brain targeting. Methods: Sumatriptan containing gliadin nanoparticles were prepared by desolvation method using Pluronic F-68 as a stabilizing agent. Results: The results show that this method is reproducible very easy and led to the efficient entrapment of drug as well as the formation of spherical particles ranging from 1 to 181 nm, respectively. The controlled release behavior of gliadin nanoparticles was evaluated both in phosphate buffer saline 7.4 pH and in phosphate buffer 6.8 pH, respectively, at 37±1°C. Their brain targeting properties were determined by the nasal route through in vitro and in vivo methods. Conclusion: The optimized nanoparticles showed higher release rate than other marketed formulation like a tablet, nasal spray this may be due to nano size of the particles, glutaraldehyde was added to this system that increased hardness and F-68 increased the stability of nanoparticles .tablet, nasal spray this may be due to nano size of the particles, glutaraldehyde was added to this system that increased hardness and F-68 increased the stability of nanoparticles. The in vivo results showed that within 15 min maximum concentration of sumatriptan was observed in brain as compare to plasma which could be due to small particle size and lipophilic nature of gliadin nanoparticles. 

A Model for the Stability of Films Stabilized by Randomly Packed Spherical Particles

Langmuir ◽  
2011 ◽  
Vol 27 (18) ◽  
pp. 11475-11480 ◽  
Author(s):  
Gareth D. M. Morris ◽  
Stephen J. Neethling ◽  
Jan J. Cilliers
Keyword(s):  
Spherical Particles ◽  
The Stability

scholarly journals SIMULATION OF THE POLY- AND MONODISPERSED GRANULAR MATERIAL. PART II: THE STABILITY STATE CHARACTERIZATION / DAUGIADISPERSIO IR VIENDISPERSIO DALELIŲ MIŠINIO ELGSENOS TYRIMAS. II DALIS: STABILUMO BŪSENŲ CHARAKTERIZAVIMAS

2012 ◽  
Vol 4 (2) ◽  
pp. 59-66 ◽  
Author(s):  
Gvidas Pocius ◽  
Robertas Balevičius
Keyword(s):  
Volume Fraction ◽  
Particle Surface ◽  
Spherical Particles ◽  
Time Step ◽  
Resonant Effect ◽  
The Stability ◽  
Gravity Acceleration ◽  
Granular Aggregate ◽  
Radius Size

In the Part I of the paper, structure of granular aggregates obtained after compaction of poly- and mono-dispersed spherical particles was characterized in terms of the coordination number, particles contacting forces and volume fraction distributions. This part of investigation deals with characterization of the state of stability under quasistatic conditions of the formed granular aggregate structure. The proposed method is based on visualization of the plane of the particle radius size plotted normally to the particle velocity vector. At the beginning of the compacting process, when the discrete particle drops down under the gravity acceleration (almost free of contact with other particles), the planes plotted the cylinder-like pattern at each time step. At the quasistatic state, when the acceleration of the settled particles tends to negligible values, the plot of these planes represents a certain texture appearing on the particle surface. For the interpretation of these textures, Shilnikov's homoclinic bifurcation theory was discussed and applied. In particular, it was found that textures specifying the quasistatic state mainly resulted from the resonant effect depending on the degree of freedom of the analyzed particles. Santrauka Šioje straipsnio dalyje pagrindinis dėmesys skiriamas viendispersinio ir daugiadispersio sferinių dalelių mišinio mikrobūsenai charakterizuoti, analizuojant atskirų mišinio dalelių stabilumą esant kvazistatiniam būviui. Tiriamos ir vizualizuojamos atskirų dalelių greičio vektorių normalinių plokštumų formuojamos tekstūros, kurios esant kvazistatiniam būviui interpretuojamos kaip tam tikri rezonansinio poveikio dariniai, gaubiantys dalelių paviršių.

scholarly journals FORMATION OF NANO-AND ULTRAFINE PALLADIUM POWDERS IN THE PRESENCE OF «RED-OX»SYSTEM«TITANIUM (III) - TITANIUM (IV)»

2020 ◽  
Vol 5 (443) ◽  
pp. 21-27
Author(s):  
Bayeshov A.B., ◽  
◽  
Gaipov T.E., ◽  
Bayeshova A.K., ◽  
◽  
...  
Keyword(s):  
Electrochemical Method ◽  
Colloidal Particles ◽  
New Technology ◽  
Atomic State ◽  
Spherical Particles ◽  
Nanodispersed Powder ◽  
Palladium Powder ◽  
The Stability ◽  
Trivalent Titanium ◽  
Over Time

The results of studies on the processes of obtaining ultra - and nanodispersed palladium powders from sulphate solutions by a combined chemical and electrochemical method in the presence of a "red-ox" system of titanium (III) - titanium (IV) are presented. It has been shown that when a titanium trivalent sulphate solution is added to a solution containing palladium (II) ions, palladium ions are immediately reduced to elemental state to form a nanodispersed powder. The completeness of the above-mentioned oxidizing-reducing reactions is established on the basis of calculating the equilibrium constant (K), which is 1034 and indicates that trivalent titanium ions completely reduce palladium ions to elemental state. Effect of initial concentration of palladium ions on amount of formed palladium powder with addition of equivalent amount of trivalent titanium ions is investigated. According to the authors, upon reduction of palladium ions, elemental palladium is formed in the atomic state, and over time, the atoms begin to combine with each other. Subsequently, atomic particles are combined into colloidal particles. It has been found that in the absence of coagulants, the colloidal palladium solution is stable for 2-3 hours, and in the presence of gelatin, the stability increases and remains for 36 hours. It was shown that in all experiments powders with spherical particles are formed, the average sizes of which range from 0.116-0.240 microns. Based on the results of the presented studies, a new technology for producing ultra - and nano-sized palladium powders is proposed.

Vacuum sublimation of Dopant‐Free Crystalline Spiro‐OMeTAD films to enhance the stability of perovskite Solar Cells

2021 ◽  
Author(s):  
Juan Ramon Sanchez-Valencia ◽  
Jose Obrero-Perez ◽  
Lidia Contreras-Bernal ◽  
Dario Jumilla ◽  
Javier Castillo-Seoane ◽  
...  
Keyword(s):  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Vacuum Sublimation ◽  
The Stability

Nanomechanical Effects

2021 ◽  
pp. 253-272
Author(s):  
C. Julian Chen
Keyword(s):  
Barrier Height ◽  
Contact Area ◽  
Soft Materials ◽  
Sample Surface ◽  
Soft Material ◽  
Measurable Effect ◽  
Tunneling Barrier ◽  
Hard Materials ◽  
Small Force ◽  
The Stability

This chapter discusses the effect of force and deformation of the tip apex and the sample surface in the operation and imaging mechanism of STM and AFM. Because the contact area is of atomic dimension, a very small force and deformation would generate a large measurable effect. Three effects are discussed. First is the stability of the STM junction, which depends on the rigidity of the material. For soft materials, hysterisis is more likely. For rigid materials, the approaching and retraction cycles are continuous and reproducible. Second is the effect of force and deformation to the STM imaging mechanism. For soft material such as graphite, force and deformation can amplify the observed corrugation. For hard materials as most metals, force and deformation can decrease the observed corrugation. Finally, the effect of force and deformation on tunneling barrier height measurements is discussed.

Effect of Sample Geometry and Placement on Iron Ore Processing by Microwave

2012 ◽  
Vol 488-489 ◽  
pp. 841-846
Author(s):  
K. Barani ◽  
S.M.J. Koleini ◽  
B. Rezai ◽  
A. Khodadadi
Keyword(s):  
Water Sample ◽  
Surface Area ◽  
Microwave Absorption ◽  
Iron Ore ◽  
Sample Surface ◽  
Sample Volume ◽  
Microwave Energy ◽  
Maximum Temperature ◽  
Effective Parameters ◽  
Ore Processing

Sample and oven factors are important in determining the magnitude and uniformity of power absorption. The effects of these parameters on water and food materials have been studied. However, interaction of microwave with minerals is poorly understood. In this research, the effect of sample and oven parameters such as sample volume and placement of sample on microwave heating of water and an iron ore material were studied and obtained data were compared. The results showed that for water heating, with increasing in sample volume from 200 to 1000cm3 the microwave energy absorbed by water was increased from 71.27 to 100%, also with increasing in sample surface area from 50.24 to 78.50 cm2 the microwave, energy absorbed by water was increased from 76.36 to 89.09%. In iron ore heating, the surface area is effective parameters only. When iron ore sample volume was increased without increasing in surface area, the microwave absorption was constant while with increasing in sample surface area from 50.24 to 126.6 cm2, the microwave energy absorbed by iron ore was increased from 36.6 to 61.82%. The maximum temperature for iron ore material was occurred at 5.7 cm distance from the center while the maximum temperature for water sample was occurred at 5cm distance from the center

scholarly journals Highly Nonlinear Solitary Waves for the Assessment of Dental Implant Mobility

2012 ◽  
Vol 80 (1) ◽  
Author(s):  
Bruk Berhanu ◽  
Piervincenzo Rizzo ◽  
Mark Ochs
Keyword(s):  
Dental Implant ◽  
Solitary Waves ◽  
Spherical Particles ◽  
Noninvasive Technique ◽  
Acid Bath ◽  
Mechanical Waves ◽  
Highly Nonlinear ◽  
Highly Nonlinear Solitary Waves ◽  
The Stability ◽  
Nonlinear Solitary Waves

In this paper we present a noninvasive technique based on the propagation of highly nonlinear solitary waves (HNSWs) to monitor the stability of dental implants. HNSWs are nondispersive mechanical waves that can form and travel in highly nonlinear systems, such as one-dimensional chains of spherical particles. The technique is based on the hypothesis that the mobility of a dental implant affects certain characteristics of the HNSWs reflected at the interface between a crystal-based transducer and the implant. To validate the research hypothesis we performed two experiments: first we observed the hydration of commercial plaster to simulate at large the osseointegration process that occurs in the oral connective tissue once a dental-endosteal threaded implant is surgically inserted; then, we monitored the decalcification of treated bovine bones immersed in an acid bath to simulate the inverse of the osseointegration process. In both series, we found a good correlation between certain characteristics of the HNSWs and the stiffness of the material under testing.

Sign in / Sign up

Export Citation Format

Share Document