scholarly journals Extension-Growth Activities of Some Cyclo Propane Derivatives, a New Class Of Antauxin.

1959 ◽  
Vol 12 (3) ◽  
pp. 257 ◽  
Author(s):  
NP Kefford
Keyword(s):  
Extension Growth ◽  
Avena Coleoptile ◽  
Coleoptile Growth ◽  
New Class ◽  
Cis And Trans

2,3-Dihydrobenzofur-2,3-yleneacetic acid, 1,2-dihydro-l,2-naphthyleneacetic acid, and cis- and trans-2,3-dihydrothionaphthen-2,3-yleneacetic acid have been shown to competitively inhibit auxin-induced growth of Avena coleoptile sections, and thus are antiauxins. trans-2-Phenylcyclopropanecarboxylic acid, 2,3dihydrothionaphthen-2,3-yleneacetic acid dioxide, and 1,2-3,4-tetrahydronaphth1,2-3,4-di(yleneacetic acid) were inactive towards coleoptile growth.

Theoretical Studies of the Physical Properties of Rodlike and Related Polymers

1988 ◽  
Vol 134 ◽  
Author(s):  
W. J. Welsh ◽  
J. E. Mark ◽  
Y. Yang ◽  
G. P. Das
Keyword(s):  
High Performance ◽  
Liquid Crystalline ◽  
Theoretical Work ◽  
Environmental Resistance ◽  
New Class ◽  
Protonated Forms ◽  
New Type ◽  
Electrooptical Properties ◽  
Cis And Trans ◽  
Strong Acids

ABSTRACTThis review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include the cis- and trans-poly(p-phenylene benzobisoxazole) (PBO), the cis- and trans-forms of the corresponding poly(pphenylene benzobisthiazole) (PBT), and the structurally similar poly(5,5ʹ-bibenzoxazole-2.2ʹ-diyl-l,3-phenylene) (AAPBO) and poly(2,5-benzoxazole) (ABPBO) and their sulfurcontaining analogues. Because of their rigidity, these polymers become highly oriented in solution and some display liquid crystalline behavior. The purpose of this paper is to summarize the authorsʹ theoretical work on the structures, conformational energies, intermolecular interactions, electronic properties, electrical conductivity, and electrooptical properties of these chains, including, in some cases, the so-called articulated forms and the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.

Synthesis of vitamin K1 analogs. A new class of vitamin K1 antagonists

1970 ◽  
Vol 48 (24) ◽  
pp. 3957-3958 ◽  
Author(s):  
J. Lowenthal ◽  
M. N. Roy Chowdhury
Keyword(s):  
Spectral Data ◽  
Vitamin K ◽  
Vitamin K1 ◽  
Trans Isomers ◽  
New Class ◽  
Cis And Trans Isomers ◽  
Cis And Trans

The synthesis of two analogs of vitamin K1, namely, 2-chloro (2) and 2-bromo (3) analogs, is described. The separation of cis and trans isomers of both these compounds on preparative t.l.c. is reported along with the spectral data.

Stimulation of Avena coleoptile growth by reduction of oxygen supply

Planta ◽  
1974 ◽  
Vol 115 (4) ◽  
pp. 345-354 ◽  
Author(s):  
Tadashi Fujii ◽  
Masami Shimokoriyama ◽  
Hiroshi Ichimura
Keyword(s):  
Oxygen Supply ◽  
Avena Coleoptile ◽  
Coleoptile Growth ◽  
Stimulation Of

scholarly journals The Lack of Effect of Cyclic Adenosine 3′:5′-Monophosphate on Avena Coleoptile Growth

1975 ◽  
Vol 55 (4) ◽  
pp. 695-698 ◽  
Author(s):  
Mira Edgerton ◽  
Morris G. Cline ◽  
Marilyn M. Rehm
Keyword(s):  
Avena Coleoptile ◽  
Coleoptile Growth

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

The microtubule associated protein (MAP) tau forms a new class of triple-stranded left-hand helical fibrous protein polymer

1992 ◽  
Vol 50 (1) ◽  
pp. 540-541
Author(s):  
G. C. Ruben ◽  
K. Iqbal ◽  
I. Grundke-Iqbal ◽  
H. Wisniewski ◽  
T. L. Ciardelli ◽  
...  
Keyword(s):  
Axial Ratio ◽  
Normal Structure ◽  
Paired Helical Filaments ◽  
Left Hand ◽  
New Class ◽  
Protein Polymer ◽  
Fibrous Protein ◽  
Protein Map ◽  
Neurotransmitter Transport ◽  
Alzheimer Neurofibrillary Tangles

In neurons, the microtubule associated protein, tau, is found in the axons. Tau stabilizes the microtubules required for neurotransmitter transport to the axonal terminal. Since tau has been found in both Alzheimer neurofibrillary tangles (NFT) and in paired helical filaments (PHF), the study of tau's normal structure had to preceed TEM studies of NFT and PHF. The structure of tau was first studied by ultracentrifugation. This work suggested that it was a rod shaped molecule with an axial ratio of 20:1. More recently, paraciystals of phosphorylated and nonphosphoiylated tau have been reported. Phosphorylated tau was 90-95 nm in length and 3-6 nm in diameter where as nonphosphorylated tau was 69-75 nm in length. A shorter length of 30 nm was reported for undamaged tau indicating that it is an extremely flexible molecule. Tau was also studied in relation to microtubules, and its length was found to be 56.1±14.1 nm.

Study of segregation in La1.8Sr0.2CuO4 superconductor by STEM-EDS microanalysis

1987 ◽  
Vol 45 ◽  
pp. 54-55
Author(s):  
T. F. Kelly ◽  
P. J. Lee ◽  
E. E. Hellstrom ◽  
D. C. Larbalestier
Keyword(s):  
Rare Earth ◽  
High Field ◽  
Transport Current ◽  
Total Thickness ◽  
New Class ◽  
Ceramic Superconductors ◽  
Current Densities ◽  
Group Ii ◽  
Eds Microanalysis

Recently there has been much excitement over a new class of high Tc (>30 K) ceramic superconductors of the form A1-xBxCuO4-x, where A is a rare earth and B is from Group II. Unfortunately these materials have only been able to support small transport current densities 1-10 A/cm2. It is very desirable to increase these values by 2 to 3 orders of magnitude for useful high field applications. The reason for these small transport currents is as yet unknown. Evidence has, however, been presented for superconducting clusters on a 50-100 nm scale and on a 1-3 μm scale. We therefore planned a detailed TEM and STEM microanalysis study in order to see whether any evidence for the clusters could be seen.A La1.8Sr0.2Cu04 pellet was cut into 1 mm thick slices from which 3 mm discs were cut. The discs were subsequently mechanically ground to 100 μm total thickness and dimpled to 20 μm thickness at the center.

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