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Irradiation Leads (irradiation + lead)

Distribution by Scientific Domains
Chemistry33%

Selected Abstracts

On the mechanism of conductivity enhancement and work function control in PEDOT:PSS film through UV-light treatment

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2010
Abderrafia Moujoud
Abstract In this work, we study the effect of UV light on the work function of PEDOT:PSS films. The authors found that UV irradiation lead to an increase in the work function. Several devices with UV exposed and unexposed PEDOT:PSS were fabricated and measured. The current,voltage characteristics have been obtained for ITO/PEDOT:PSS/InZnO samples. We found that UV irradiated devices show better electrical characteristics and lead to Ohmic contact. The trend in device performance was explained by the observed changes in the work function of the PEDOT:PSS layer. The change in the work function was measured by ultraviolet photoelectron spectroscopy. The structural and morphological properties of PEDOT:PSS films with and without UV treatment were investigated by X-ray photoelectron spectroscopy and atomic force microscopy techniques. The change in the work function of PEDOT:PSS is mainly due to the surface conformational change. The stability of devices with and without UV treatment has been investigated under normal environmental conditions. Electrical properties of the devices have been studied over a period of 30 and 60 days. The stability tests show that devices with UV treatment are more stable that those without UV treatment. [source]

Accelerated Heck reaction using ortho -palladated complex with controlled microwave heating

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2009
Abdol R. Hajipour
Abstract Palladium-catalyzed Heck couplings utilizing [Pd{C6H2(CH2CH2NH2)-(OMe)2,3,4} (µ-Br)]2 palladacycle catalyst and microwave irradiation lead to formation of different coupling products. This complex is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even less reactive chlorides. The cross-coupled products were produced in excellent yields. The reaction time was reduced from hours to minutes and full conversion was achieved under microwave irradiation. Copyright © 2009 John Wiley & Sons, Ltd. [source]

The anti-inflammatory mechanism of 635 nm light-emitting-diode irradiation compared with existing COX inhibitors

LASERS IN SURGERY AND MEDICINE, Issue 7 2007
Wonbong Lim PhD
Abstract Background and Objectives Inhibition of cyclooxygenase (COX) and prostaglandin E2 (PGE2) protects cells against cell injury in specific pathophysiological situations: inflammation and oxidative stress. Although the anti-inflammatory effects have been reported in clinical fields for specific wavelength irradiation during wound healing, the physiological mechanism has not been clarified yet. The aim of the present study is to investigate the anti-inflammatory mechanism of 635 nm light-emitting-diode (LED) irradiation compared with existing COX inhibitors. Study Design/Materials and Methods The present study investigated anti-inflammatory effects of 635 nm irradiation on PGE2 release, COX and phospholipase A2 (PLA2) expression, and reactive oxygen species (ROS) dissociation in arachidonic acid (AA)-treated human gingival fibroblast (hGF). These results were compared with their existing COX inhibitors: indomethacin and ibuprofen. The PGE2 release was measured by enzyme immunoassay, the COX expression was measured by western blot and reverse transcriptase polymerase chain reaction (RT-PCR), and ROS level was measured by flow cytometry, laser scanning confocal microscope and RT-PCR. Results Results showed that 635 nm irradiation and existing COX inhibitors inhibit expression of COX and PGE2 release. Unlike indomethacin and ibuprofen, 635 nm irradiation leads to a decrease of ROS levels and mRNA expression of cytosolic phospholipase A2 (cPLA2) and secretary phospholipase A2 (sPLA2). Conclusion Taken together, 635 nm irradiation, unlike indomethacin and ibuprofen, can directly dissociate the ROS. This inhibits cPLA2, sPLA2, and COX expression, and results in the inhibition of PGE2 release. Thus, we suggest that 635 nm irradiation inhibits PGE2 synthesis like COX inhibitor and appears to be useful as an anti-inflammatory tool. Lesers Surg. Med. 39:614,621, 2007. © 2007 Wiley-Liss, Inc. [source]

Activation of HIV in Human Skin by Ultraviolet B Radiation and its Inhibition by NF,B Blocking Agents,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2001
Joan Breuer-McHam
ABSTRACT To determine whether ultraviolet B (UVB) irradiation leads to activation of HIV in human skin, we conducted prospective and controlled studies in two academic medical centers in Texas from July 1995 to April 1999. HIV-positive patients with UV-treatable skin diseases were enrolled at each center, 18 subjects at one and 16 at the other. In one center, specimens from lesional and nonlesional skin biopsies were taken before and after sham- or UVB-irradiation administered in vivo or in vitro. In the other center, UVB phototherapy was administered three times weekly and specimens from skin biopsies were taken before and after 2 weeks (six treatments). Cutaneous HIV load was assessed using reverse transcriptase-polymerase chain reaction and reverse transcriptase-polymerase chain reaction in situ hybridization. UVB irradiation led to a 6,10-fold increase in the number of HIV in skin. To ascertain a role for nuclear factor kappa B (NF,B) in UVB-inducible HIV activation, two types of blockers, NF,B oligonucleotide decoy and sodium salicylate, were tested; each inhibited UVB-inducible HIV activation in skin partially. We conclude that UVB irradiation leads to increased numbers of HIV in human skin via processes that include release of cytoplasmic NF,B. [source]

Acceleration of Suzuki,Miyaura- and Stille-type Coupling Reactions by Irradiation with Near-UV-A Light

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 12 2008
Giovanni Imperato Dr.
Abstract Irradiation of a palladium catalyst bearing UV-A-absorbing phosphine ligands with low-intensity UV-A light leads to higher conversions of reactants at lower temperatures and an increased selectivity towards the cross-coupling product in Suzuki,Miyaura- and Stille-type reactions. The examples studied illustrate that a selective energy input into the catalyst by irradiation leads to more selective conversions under milder reaction conditions. With the availability of affordable and energy-efficient UV-A LED light sources, selective heating of the catalyst by light can be envisaged as a general strategy to increase the performance of a catalyst. [source]