Isotactic polystyrene/cis-decaline mixtures: phase diagram and molecular structures

1994 ◽  
Vol 272 (1) ◽  
pp. 36-47 ◽  
Author(s):  
J. M. Guenet ◽  
A. Menelle ◽  
V. Schaffhauser ◽  
P. Terech ◽  
A. Thierry
Keyword(s):  
Phase Diagram ◽  
Molecular Structures ◽  
Isotactic Polystyrene

Molecular structures in isotactic polystyrene thermoreversible gels

1990 ◽  
Vol 23 (2) ◽  
pp. 540-548 ◽  
Author(s):  
Marc Klein ◽  
Annie Brulet ◽  
Jean Michel Guenet
Keyword(s):  
Molecular Structures ◽  
Isotactic Polystyrene ◽  
Thermoreversible Gels

scholarly journals Study of Molecular Flexibility Operated Mesomorphism

2015 ◽  
Vol 58 ◽  
pp. 16-25 ◽  
Author(s):  
B.B. Jain ◽  
R.B. Patel
Keyword(s):  
Molecular Structure ◽  
Phase Diagram ◽  
Homologous Series ◽  
Nematic Phase ◽  
Molecular Structures ◽  
Transition Curve ◽  
The Novel ◽  
Normal Manner ◽  
Thermal Data ◽  
Transition Curves

Homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC14H29(P) of chalconyl novel derivatives have been synthesized and studied with a views to understand and establish the relation between molecular structure and the liquid crystal (LC) properties of thermotropic mesomorphs Series consists of thirteen homologues. Five homologues (C1 to C5) are nonliquid crystal (NLC) and the rest of the homologues (C6 to C18) are enantiotropically nematogenic without exhibition of smectic property. Transition temperatures and textures were determined by an optical polarizing microscope equipped with a heating stage (POM). Transition curves of a phase diagram (N-I and Cr-I/N) behaved in normal manner. N-I transition curve exhibited odd-even effect with negligible abnormality in its behaviour at the C14 homologue. Thermal stability for nematic is 99.75°C.The degree of mesomorphism vary minimum 19°C at the C6 homologue to maximum 28°C at the C8 homologue. Analytical and spectral data confirms the molecular structures of the novel homologues. Evaluated thermal data of present novel series are compared with other structurally similar homologous series. Textures of Nematic phase are threded or schlieren.

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

Scanning tunneling microscopy (STM) of DNA and RNA

1989 ◽  
Vol 47 ◽  
pp. 34-35
Author(s):  
Patricia G. Arscott ◽  
Gil Lee ◽  
Victor A. Bloomfield ◽  
D. Fennell Evans
Keyword(s):  
Molecular Structures ◽  
Inorganic Materials ◽  
Resolving Power ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Form And Function ◽  
Dna And Rna ◽  
Calf Thymus ◽  
And Function ◽  
The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

Molecular architecture and functions of the neuronal cytoskeleton

1990 ◽  
Vol 48 (3) ◽  
pp. 2-3
Author(s):  
Nobutaka Hirokawa
Keyword(s):  
Major Elements ◽  
Molecular Structures ◽  
Organelle Transport ◽  
Molecular Architecture ◽  
Neuronal Morphogenesis ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function ◽  
Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

New developments in the ab initio determination of transition metal alloys phase diagram

1993 ◽  
Vol 90 ◽  
pp. 249-254 ◽  
Author(s):  
C Wolverton ◽  
M Asta ◽  
S Ouannasser ◽  
H Dreyssé ◽  
D de Fontaine
Keyword(s):  
Phase Diagram ◽  
Transition Metal ◽  
Ab Initio ◽  
Metal Alloys ◽  
New Developments ◽  
Transition Metal Alloys

Phase diagram calculation of Ti-Zr-X systems

1993 ◽  
Vol 90 ◽  
pp. 175-180 ◽  
Author(s):  
Li Lin ◽  
L Delaey ◽  
P Wollants ◽  
O Van Der Biest
Keyword(s):  
Phase Diagram ◽  
Phase Diagram Calculation

Metallic phase stabilization and phase diagram of (ET)3(HSO4)2

1991 ◽  
Vol 1 (10) ◽  
pp. 1365-1370 ◽  
Author(s):  
N. D. Kush ◽  
V. N. Laukhin ◽  
A. I. Schegolev ◽  
E. B. Yagubskii ◽  
E. Yu. Alikberova ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Metallic Phase ◽  
Phase Stabilization
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