Solar cells require symmetry-breaking features such as built-in electrostatic fields and/or effective fields. We examine an organic heterojunction structure with no built-in field and explore the origins of its current-voltage characteristics and open circuit voltage (VOC). Two behaviors are found: (1) VOC=VI+m[(HOMO(D) - (LUMO(A)] where m≈1, the intercept (VI) is determined by interface recombination kinetics, HOMO(D) is the donor highest occupied molecular orbital, and LUMO(A) is the acceptor lowest unoccupied molecular orbital; (2) if interface recombination is suppressed, VOC is controlled by bulk/contact recombination and is not dependent upon HOMO(D) - LUMO(A).
The purpose of this clinical study is to assess whether calcium hydroxide as an intracanal medication affects post-treatment pain in teeth especially odontogenic pain which comes from inflammation of the pulp and periradicular tissues when compared with no intracanal medication.From 213 patients who has been treated 237 root canals due to significant pain (moderate-tosevere), we recorded their age, sex, treated tooth, degree of pain, pre-operative states of the tooth. We classified patients into 2 test group; Group 1 (not gain intracanal Ca(OH)2), Group 2 (gain intracanal Ca(OH)2). Through the survey from the patients, we let them write down the occurrence and degree of post-treatment pain in 4hours, 2days, 7days after treatment as none, mild, moderate or severe. The followings were evaluated; the overall incidence of flare-ups, the overall incidence of post-treatment pain in each group at each time period, the incidence of post-treatment pain in each group at each time period as related to pre-operative states of the teeth. These were compared statistically with Chi-square analysis (p < 0.05).Under the condition of this investigation, no difference was observed in the incidence of post-treatment pain between the two groups. Therefore, Ca(OH)2 as intracanal medication had no effect on preventing or decreasing the post-treatment pain. [J Kor Acad Cons Dent 31(2):86-95, 2006]
We describe the use of hard etching methods to create nanodimensional channels and their use as templates for the formation of polymer filament arrays with precise dimensional and orientational control in a single integrated step. The procedure is general as illustrated by the radical, coordination, and photochemical polymerizations that were performed in these nanochannels. The nanochannel templates (20 nm high, 20-200 nm wide, and 100 mum long) were fabricated by the combined use of electron-beam lithography and a sacrificial metal line etching technique. Radical polymerization of acrylates, metal-catalyzed polymerization of norbornene, and photochemical polymerization of 1,4-diiodothiophene were carried out in these nanochannels. The polymers grown follow the dimensions and orientation of the channels, and the polymer filaments can be released without breaking. The approach opens up the possibility of just-in-place manufacturing and processing of patterns and devices from nanostructured polymers using well-established polymer chemistry.
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