1,582 research outputs found
Electrical current distribution across a metal-insulator-metal structure during bistable switching
Combining scanning electron microscopy (SEM) and electron-beam-induced
current (EBIC) imaging with transport measurements, it is shown that the
current flowing across a two-terminal oxide-based capacitor-like structure is
preferentially confined in areas localized at defects. As the thin-film device
switches between two different resistance states, the distribution and
intensity of the current paths, appearing as bright spots, change. This implies
that switching and memory effects are mainly determined by the conducting
properties along such paths. A model based on the storage and release of charge
carriers within the insulator seems adequate to explain the observed memory
effect.Comment: 8 pages, 7 figures, submitted to J. Appl. Phy
Hafnium carbide formation in oxygen deficient hafnium oxide thin films
On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO)
contaminated with adsorbates of carbon oxides, the formation of hafnium carbide
(HfC) at the surface during vacuum annealing at temperatures as low as 600
{\deg}C is reported. Using X-ray photoelectron spectroscopy the evolution of
the HfC surface layer related to a transformation from insulating into
metallic state is monitored in situ. In contrast, for fully stoichiometric
HfO thin films prepared and measured under identical conditions, the
formation of HfC was not detectable suggesting that the enhanced adsorption
of carbon oxides on oxygen deficient films provides a carbon source for the
carbide formation. This shows that a high concentration of oxygen vacancies in
carbon contaminated hafnia lowers considerably the formation energy of hafnium
carbide. Thus, the presence of a sufficient amount of residual carbon in
resistive random access memory devices might lead to a similar carbide
formation within the conducting filaments due to Joule heating
Characterization of the Active Site of Acetylcholinesterases by Application of Sterically Modified Acetylcholine Homologues
Our aim was to find steric limitations for the model of the
active site of acetylcholinesterase and cho1inesterase. For thi<s purpose
we used homologues of acetylcholine with hydrocarbon chains
of increasing size at the cationic head. Catalysis of hydrolysis
ceased for both enzymes, when the methyl groups of the cationic
head of acetylcholine were substituted by three n-propyl groups.
With data already documented in the literature and our additional
experiments, under the same conditions, we were able to present
models of the active sites for both enzymes
Characterization of the Active Site of Acetylcholinesterases by Application of Sterically Modified Acetylcholine Homologues
Our aim was to find steric limitations for the model of the
active site of acetylcholinesterase and cho1inesterase. For thi<s purpose
we used homologues of acetylcholine with hydrocarbon chains
of increasing size at the cationic head. Catalysis of hydrolysis
ceased for both enzymes, when the methyl groups of the cationic
head of acetylcholine were substituted by three n-propyl groups.
With data already documented in the literature and our additional
experiments, under the same conditions, we were able to present
models of the active sites for both enzymes
DISTRIBUTION AND KINETICS OF 14C-VECURONIUM IN RATS AND MICE
The distribution and kinetics of 14C-vecuronium were studied in rats and mice. 14C-Vecuronium accumulated rapidly in the liver. Both unchanged and metabolized vecuronium were excreted with the bile into the intestines and stomach. Reabsorption in the gut was probably responsible for an enterohepatic increase in radioactivity in the liver after one hour. Excretion through the kidneys increased continuously from low values after the initial peak. Binding in compartments with acid mucopolysaccharides such as cartilage, connective tissue etc., was less important. Bloodbrain barrier and placenta were permeable only to a small degre
Π§ΠΈΡΠ»Π΅Π½Π½ΠΎΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π²Π»ΠΈΡΠ½ΠΈΡ ΡΡΠ»ΠΎΠ²ΠΈΠΉ ΡΠ°ΡΠΏΡΠ»Π΅Π½ΠΈΡ Π²ΠΎΠ΄Ρ Π½Π° ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ Π² ΡΠ»Π΅Π΄Π΅ "Π²ΠΎΠ΄ΡΠ½ΠΎΠ³ΠΎ ΡΠ½Π°ΡΡΠ΄Π°"
Π‘ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ Π½Π΅ΡΠΊΠΎΠ»ΡΠΊΠΈΡ
ΠΌΠΎΠ΄Π΅Π»Π΅ΠΉ "Π²ΠΎΠ΄ΡΠ½ΡΡ
ΡΠ½Π°ΡΡΠ΄ΠΎΠ²" ΠΌΠ°Π»ΡΡ
ΡΠ°Π·ΠΌΠ΅ΡΠΎΠ² Π²ΡΠΏΠΎΠ»Π½Π΅Π½ΠΎ ΡΠΈΡΠ»Π΅Π½Π½ΠΎΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΌΠ°ΠΊΡΠΎΡΠΊΠΎΠΏΠΈΡΠ΅ΡΠΊΠΈΡ
Π·Π°ΠΊΠΎΠ½ΠΎΠΌΠ΅ΡΠ½ΠΎΡΡΠ΅ΠΉ ΠΈΡΠΏΠ°ΡΠ΅Π½ΠΈΡ ΠΌΠΎΠ½ΠΎΠ΄ΠΈΡΠΏΠ΅ΡΡΠ½ΠΎΠΉ ΡΠΎΠ²ΠΎΠΊΡΠΏΠ½ΠΎΡΡΠΈ ΠΊΠ°ΠΏΠ΅Π»Ρ ΡΠΎΠ½ΠΊΠΎΡΠ°ΡΠΏΡΠ»Π΅Π½Π½ΠΎΠΉ Π²ΠΎΠ΄Ρ ΠΏΡΠΈ ΠΏΡΠΎΡ
ΠΎΠΆΠ΄Π΅Π½ΠΈΠΈ ΡΠ΅ΡΠ΅Π· Π²ΡΡΠΎΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΡΠ΅ ΠΏΡΠΎΠ΄ΡΠΊΡΡ ΡΠ³ΠΎΡΠ°Π½ΠΈΡ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΈΠ½ΡΠ΅Π³ΡΠ°Π»ΡΠ½ΡΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ ΡΠ΅ΠΏΠ»ΠΎΠΌΠ°ΡΡΠΎΠΏΠ΅ΡΠ΅Π½ΠΎΡΠ° ΠΎΡ ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΡ ΠΏΠ»ΠΎΡΠ°Π΄Π΅ΠΉ ΠΈΡΠΏΠ°ΡΠ΅Π½ΠΈΡ ΠΈ ΠΏΠ»ΠΎΡΠ°Π΄Π΅ΠΉ, Π·Π°Π½ΠΈΠΌΠ°Π΅ΠΌΡΡ
"Π²ΠΎΠ΄ΡΠ½ΡΠΌ ΡΠ½Π°ΡΡΠ΄ΠΎΠΌ". ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ ΡΡΠ»ΠΎΠ²ΠΈΡ ΡΠ°ΡΠΏΡΠ»Π΅Π½ΠΈΡ Π²ΠΎΠ΄Ρ Π΄Π»Ρ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΡ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ Π² Π·ΠΎΠ½Π΅ Π³ΠΎΡΠ΅Π½ΠΈΡ
Synthesis of 1-[(Triisopropylsilyl)ethynyl]-1 lambda(3),2-benziodoxol-3(1H)-one and Alkynylation of Indoles, Thiophenes, and Anilines
An efficient procedure was developed for the synthesis of 1-[(triisopropylsilyl)ethynyl]-1 lambda(3),2-benziodoxol-3(1H)-one on a 100-mmol (36-g) scale. The benziodoxolone can be used for the gold-catalyzed direct alkynylation of indole, 2-hexylthiophene, or N,N-dibenzylaniline on a 5- to 10-mmol scale
Para-Selective Gold-Catalyzed Direct Alkynylation of Anilines
A method for the para-selective alkynylation of anilines is reported using AuCl as catalyst and triisopropylsilylethynyl-1,2-benziodoxol-3(1H)-one (TIPS-EBX) as an electrophilic acetylene equivalent. Para-alkynyl anilines substituted at positions 2 or 3 were obtained in one step from simple anilines under mild conditions (room temperature to 60 degrees C) under air. The methodology could also be extended to the alkynylation of trimethoxybenzenes
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