Synthesis and Optical Properties of a Novel Oligobipyridine

2001 ◽  
Vol 665 ◽  
Author(s):  
Y. J. Fu ◽  
T.K.S. Wong ◽  
H.X. Zhang ◽  
G. M. Wang ◽  
X. Hu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Conjugated Polymers ◽  
Double Layer ◽  
Single Layer ◽  
Emission Spectra ◽  
Amorphous Film ◽  
Emission Peak ◽  
Conjugation Length ◽  
Emission Color ◽  
Film State

ABSTRACTIn this paper, 5,5' –bis [ 4'– methyl- ( 2,2'– bipyridin– 4- yl)- ethyl ]- 2,2'– bipyridine (BMBPYBPY), a partially conjugated derivative of oligobipyridine, has been synthesized and found to show strong photoluminescence (PL). Compared with the pyridine-based conjugated polymers, the shortened conjugation length shifts the emission color from green to violet-blue. The effects of morphology on its PL properties have been studied. From its as-precipitated powder state, an emission peak at 418 nm can be observed. However the emission spectra from its diffused states such as doped in KBr, or dissolved in CHCl3, as well as from its amorphous film state fabricated by vacuum evaporation are more complex. Also carried out are preliminary electroluminescent studies. Single layer devices ITO/BMBPYBPY/Al do not emit although current can be observed prominently. Double layer devices ITO/TPD/ BMBPYBPY/Al show emissions both from TPD and BMBPYBPY.

SYNTHESIS AND ELECTROLUMINESCENT PROPERTIES OF POLYAZOMETHINE-TYPE CONJUGATED POLYMERS CONTAINING HETEROCYCLIC PHENOTHIAZINE AND CARBAZOLE MOIETY

2005 ◽  
Vol 14 (04) ◽  
pp. 545-553 ◽  
Author(s):  
JEON WOO JEONG ◽  
YOUNGHWAN KWON ◽  
JEONG JU BAEK ◽  
LEE SOON PARK ◽  
EUI-WAN LEE ◽  
...  
Keyword(s):  
Schiff Base ◽  
Conjugated Polymers ◽  
Organic Solvents ◽  
Double Layer ◽  
Polymer Structure ◽  
The Other ◽  
Side Chains ◽  
Emission Color ◽  
Alkyl Side Chains

Polyazomethine-type conjugated polymers were synthesized by Schiff-base reaction. One was poly(PZ-PBI) with alternating phenothiazine (PZ) and azomethine units (-C = N-) , and the other was poly(CZ-PBI) comprising alternating carbazole (CZ) and azomethine groups. Conjugated polymers exhibited improved solubility in common organic solvents due to alkyl side chains on phenothiazine and carbazole rings as well as polar azomethine groups in main chains. Single- and double-layer PLEDs were fabricated. Their electroluminescent properties were studied from the viewpoint of polymer structure vs. emission color and efficiency.

SYNTHESIS AND ELECTRO-OPTICAL PROPERTIES OF BLUE EMITTING POLY(BP-alt-BCV) CONJUGATED POLYMERS

2005 ◽  
Vol 14 (04) ◽  
pp. 535-543
Author(s):  
JEONG JU BAEK ◽  
YOUNG CHUL JEONG ◽  
LEE SOON PARK ◽  
JUNG KYUNG LEE ◽  
YOON SOO HAN ◽  
...  
Keyword(s):  
Optical Properties ◽  
Conjugated Polymers ◽  
Double Layer ◽  
Phosphonic Acid ◽  
Conjugated Polymer ◽  
Absorption Maximum ◽  
Blue Emission ◽  
Diethyl Ester ◽  
Visible Absorption ◽  
Uv Visible

A new blue electroluminescent conjugated polymer, poly(BP-alt-BCV), was prepared by Hornor–Emmons polycondensation of [5-carbazol-9-yl-3-(diethoxy-phosphorylmethyl)-2-(2-ethyl-hexyloxy)-benzyl]-phosphonic acid diethyl ester (PHBP) and 4,4′-biphenyldicarboxaldehyde (BPCA) in the presence of tert-BuOK in THF. UV-visible absorption maximum (λmax,UV, π-π* transition) of poly(BP-alt-BCV) was measured at 340 nm. PL maximum (λmax,PL) values of poly(BP-alt-BCV) were obtained at 406 and 430 nm, when excited at its own λmax,UV. It was found that double layer [ITO/poly(BP-alt-BCV)/Alq3 (50 Å)/Al] PLED exhibited maximum EL peak at 440 nm and blue emission (x = 0.1794, y = 0.1878), similar to the NTSC standard blue (x = 0.14, y = 0.08).

Cracking at the fold in double layer coated paper: the influence of latex and starch composition

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 93-99
Author(s):  
SEYYED MOHAMMAD HASHEMI NAJAFI ◽  
DOUGLAS BOUSFIELD, ◽  
MEHDI TAJVIDI
Keyword(s):  
Mechanical Properties ◽  
Double Layer ◽  
Starch Content ◽  
Single Layer ◽  
Double Layers ◽  
Coated Paper ◽  
Coated Papers ◽  
Coating Layers ◽  
Scanned Images ◽  
Packaging Paper

Cracking at the fold of publication and packaging paper grades is a serious problem that can lead to rejection of product. Recent work has revealed some basic mechanisms and the influence of various parameters on the extent of crack area, but no studies are reported using coating layers with known mechanical properties, especially for double-coated systems. In this study, coating layers with different and known mechanical properties were used to characterize crack formation during folding. The coating formulations were applied on two different basis weight papers, and the coated papers were folded. The binder systems in these formulations were different combinations of a styrene-butadiene latex and mixtures of latex and starch for two different pigment volume concentrations (PVC). Both types of papers were coated with single and double layers. The folded area was scanned with a high-resolution scanner while the samples were kept at their folded angle. The scanned images were analyzed within a constant area. The crack areas were reported for different types of papers, binder system and PVC values. As PVC, starch content, and paper basis weight increased, the crack area increased. Double layer coated papers with high PVC and high starch content at the top layer had more cracks in comparison with a single layer coated paper, but when the PVC of the top layer was low, cracking area decreased. No measurable cracking was observed when the top layer was formulated with a 100% latex layer.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

Single layer versus double layer suture for anastomosis of the gastrointestinal tract

2009 ◽  
Author(s):  
Alvaro Sanabria ◽  
Gabriel Gomez ◽  
Eduardo Valdivieso ◽  
C Bermudez
Keyword(s):  
Gastrointestinal Tract ◽  
Double Layer ◽  
Single Layer ◽  
Layer Versus

Single layer versus double layer suture for anastomosis of the gastrointestinal tract

2005 ◽  
Author(s):  
Alvaro Sanabria ◽  
Gabriel Gomez ◽  
Eduardo Valdivieso ◽  
C Bermudez
Keyword(s):  
Gastrointestinal Tract ◽  
Double Layer ◽  
Single Layer ◽  
Layer Versus

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

scholarly journals A Trial Acoustic Improvement in a Lecture Hall with MPP Sound Absorbers and FDTD Acoustic Simulations

2021 ◽  
Vol 11 (6) ◽  
pp. 2445
Author(s):  
Matteo Cingolani ◽  
Giulia Fratoni ◽  
Luca Barbaresi ◽  
Dario D’Orazio ◽  
Brian Hamilton ◽  
...  
Keyword(s):  
Double Layer ◽  
Speech Intelligibility ◽  
Single Layer ◽  
Lecture Hall ◽  
Full Spectrum ◽  
Metal Printing ◽  
Specific Impedance ◽  
Specific Material ◽  
Acoustic Treatment ◽  
Difference Time

Sound absorbing micro-perforated panels (MPPs) are being increasingly used because of their high quality in terms of hygiene, sustainability and durability. The present work investigates the feasibility and the performance of MPPs when used as an acoustic treatment in lecture rooms. With this purpose, three different micro-perforated steel specimens were first designed following existing predictive models and then physically manufactured through 3D additive metal printing. The specimens’ acoustic behavior was analyzed with experimental measurements in single-layer and double-layer configurations. Then, the investigation was focused on the application of double-layer MPPs to the ceiling of an existing university lecture hall to enhance speech intelligibility. Numerical simulations were carried out using a full-spectrum wave-based method: a finite-difference time-domain (FDTD) code was chosen to better handle time-dependent signals as the verbal communication. The present work proposes a workflow to explore the suitability of a specific material to speech requirements. The measured specific impedance complex values allowed to derive the input data referred to MPPs in FDTD simulations. The outcomes of the process show the influence of the acoustic treatment in terms of reverberation time (T30) and sound clarity (C50). A systematic comparison with a standard geometrical acoustic (GA) technique is reported as well.

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