Surface properties and crystallinity of Pinus taeda and Hymenaea stilbocarpa treated at low temperatures in different grain directions

2020 ◽  
Vol 17 (1) ◽  
pp. 46-53 ◽  
Author(s):  
S. N. C. dos Santos ◽  
T. H. de Almeida ◽  
M. R. Sardela ◽  
F. A. R. Lahr ◽  
D. Gonçalves
Keyword(s):  
Pinus Taeda ◽  
Surface Properties ◽  
Low Temperatures

Growth and Surface Properties of Boehmite Nanofibers and Nanotubes at Low Temperatures Using a Hydrothermal Synthesis Route

Langmuir ◽  
2007 ◽  
Vol 23 (19) ◽  
pp. 9850-9859 ◽  
Author(s):  
Yanyan Zhao ◽  
Ray L. Frost ◽  
Wayde N. Martens ◽  
Huai Yong Zhu
Keyword(s):  
Hydrothermal Synthesis ◽  
Surface Properties ◽  
Low Temperatures ◽  
Synthesis Route

scholarly journals Multi-Scale Simulation of Injection Molding Process with Micro–Features Replication: Relevance of Rheological Behaviour and Crystallization

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3236
Author(s):  
Sara Liparoti ◽  
Vito Speranza ◽  
Roberto Pantani ◽  
Giuseppe Titomanlio
Keyword(s):  
Injection Molding ◽  
Surface Properties ◽  
Low Temperatures ◽  
Rheological Behaviour ◽  
Cavity Surface ◽  
Injection Molding Process ◽  
Multiscale Approach ◽  
Molding Process ◽  
Micro Features ◽  
Replication Accuracy

The possibility of tailoring key surface properties through the injection molding process makes it intriguing from the perspective of sustainability enhancement. The surface properties depend on the replication accuracy of micro and nanostructures on moldings; such an accuracy is enhanced with cavity temperature. The simulation of the injection molding process is very challenging in the presence of micro and nanostructures on the cavity surface; this does not allow for the neglect of phenomena generally considered not to influence the overall process. In this paper, a multiscale approach was proposed: in the first step, the simulation of the overall process was conducted without considering the presence of the microstructure; in the second step the outputs of the first step were used as an input to simulate the replication of the microfeature. To this purpose, a lubrication approximation was adopted, and the contribution of the trapped air, which slows down the polymer advancement, was accounted for. A modification of the viscosity equation was also proposed to describe the rheological behavior of isotactic polypropylene at very low temperatures. Concerning the microcavity filling simulation, the modification of the viscosity description at low temperatures consistently describes the process, in terms of polymer solidification. Concerning the replication accuracy, it increases with the cavity surface temperature, consistently with the experimental observations.

Biological and Surface Properties of C-Type Virus Particles Produced by Novikoff Ascites Hepatoma Cells

1977 ◽  
Vol 35 ◽  
pp. 388-389
Author(s):  
D.C. Hixson ◽  
J.C. Chan ◽  
J.M. Bowen ◽  
E.F. Walborg
Keyword(s):  
Surface Properties ◽  
Ricinus Communis ◽  
Rat Kidney ◽  
Leukemia Virus ◽  
Viral Envelope ◽  
Virus Particles ◽  
Chemically Induced ◽  
Sarcoma Virus ◽  
Hepatocarcinoma Cells ◽  
Type C

Several years ago Karasaki (1) reported the production of type C virus particles by Novikoff ascites hepatocarcinoma cells. More recently, Weinstein (2) has reported the presence of type C virus particles in cell cultures derived from transplantable and primary hepatocellular carcinomas. To date, the biological function of these virus and their significance in chemically induced hepatocarcinogenesis are unknown. The present studies were initiated to determine a possible role for type C virus particles in chemically induced hepatocarcinogenesis. This communication describes results of studies on the biological and surface properties of type C virus associated with Novikoff hepatocarcinoma cells.Ecotropic and xenotropic murine leukemia virus (MuLV) activity in ascitic fluid of Novikoff tumor-bearing rats was assayed in murine sarcoma virus transformed S+L- mouse cells and S+L- mink cells, respectively. The presence of sarcoma virus activity was assayed in non-virus-producing normal rat kidney (NRK) cells. Ferritin conjugates of concanavalin A (Fer-Con wheat germ agglutinin (Fer-WGA), and Ricinus communis agglutinins I and II (Fer-RCAI and Fer-RCAII) were used to probe the structure and topography of saccharide determinants present on the viral envelope.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

Ultrastructure of the soil fungus, Geomyces pannorus

1984 ◽  
Vol 42 ◽  
pp. 738-739
Author(s):  
J. A. Traquair ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fine Structure ◽  
Low Temperatures ◽  
Soil Fungus ◽  
Organic Soils ◽  
Anatomical Studies ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Scanning Electron

With the advent of improved dehydration techniques, scanning electron microscopy has become routine in anatomical studies of fungi. Fine structure of hyphae and spore surfaces has been illustrated for many hyphomycetes, and yet, the ultrastructure of the ubiquitous soil fungus, Geomyces pannorus (Link) Sigler & Carmichael has been neglected. This presentation shows that scanning and transmission electron microscopical data must be correlated in resolving septal structure and conidial release in G. pannorus.Although it is reported to be cellulolytic but not keratinolytic, G. pannorus is found on human skin, animals, birds, mushrooms, dung, roots, and frozen meat in addition to various organic soils. In fact, it readily adapts to growth at low temperatures.

Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

1991 ◽  
Vol 49 ◽  
pp. 900-901 ◽  
Author(s):  
Alain Claverie ◽  
Zuzanna Liliental-Weber
Keyword(s):  
Transport Properties ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Lattice Parameter ◽  
Crystalline Quality ◽  
Insulating Properties ◽  
Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

Point and planar defects in the iron sulfide compounds Fe1-xS

1984 ◽  
Vol 42 ◽  
pp. 434-435
Author(s):  
Thao A. Nguyen
Keyword(s):  
Low Temperatures ◽  
Direct Evidence ◽  
Iron Sulfide ◽  
Planar Defects ◽  
Selective Area ◽  
Vacancy Ordering ◽  
Different Types ◽  
Lattice Images ◽  
The Subject ◽  
Beam Lattice

It is well known that the large deviations from stoichiometry in iron sulfide compounds, Fe1-xS (0≤x≤0.125), are accommodated by iron vacancies which order and form superstructures at low temperatures. Although the ordering of the iron vacancies has been well established, the modes of vacancy ordering, hence superstructures, as a function of composition and temperature are still the subject of much controversy. This investigation gives direct evidence from many-beam lattice images of Fe1-xS that the 4C superstructure transforms into the 3C superstructure (Fig. 1) rather than the MC phase as previously suggested. Also observed are an intrinsic stacking fault in the sulfur sublattice and two different types of vacancy-ordering antiphase boundaries. Evidence from selective area optical diffractograms suggests that these planar defects complicate the diffraction pattern greatly.

Inelastic scattering at surfaces and interfaces

1986 ◽  
Vol 44 ◽  
pp. 392-393
Author(s):  
R. H. Ritchie ◽  
A. Howie
Keyword(s):  
Inelastic Scattering ◽  
Surface Properties ◽  
Correlation Energy ◽  
Condensed Matter ◽  
Charged Particles ◽  
Condensed Matter Physics ◽  
Optical Phonons ◽  
Exchange Correlation ◽  
Surfaces And Interfaces ◽  
Inelastic Interactions

An important part of condensed matter physics in recent years has involved detailed study of inelastic interactions between swift electrons and condensed matter surfaces. Here we will review some aspects of such interactions.Surface excitations have long been recognized as dominant in determining the exchange-correlation energy of charged particles outside the surface. Properties of surface and bulk polaritons, plasmons and optical phonons in plane-bounded and spherical systems will be discussed from the viewpoint of semiclassical and quantal dielectric theory. Plasmons at interfaces between dissimilar dielectrics and in superlattice configurations will also be considered.

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