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Journal ArticleDOI

Photopolarization process in orthorhombic lead monoxide

01 Jun 1982-Materials Letters (North-Holland)-Vol. 1, Iss: 1, pp 11-13

TL;DR: In this article, two peaks have been observed at 320 and 370 K in the TSD spectra corresponding to trapping levels at 0.3 and 0.5 eV, respectively.

AbstractThermally stimulated depolarization (TSD) currents have been studied for lead monoxide powder after dark- and photo-polarization. Two peaks have been observed at 320 and 370 K in the TSD spectra corresponding to trapping levels at 0.3 and 0.5 eV, respectively. From the time and intensity dependence of these peaks it has been shown that the dark polarization is mainly due to the trapping of carriers at shallow levels located at 0.3 eV whereas the photopolarization arises from the carriers trapped at deeper levels corresponding to the second peak.

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Citations
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Journal ArticleDOI
TL;DR: The presence of carboxylate groups in CMCS not only enhanced antimicrobial activity but also enabled Ag ions chelating ability to induce the in situ formation of Ag nanoparticles (AgNPs).
Abstract: Carboxymethyl chitosan (CMCS) was known to have a much better antimicrobial activity than chitosan due to the increased cationic –NH 3 + groups resulted from the intra- and intermolecular interactions between the carboxyl and amino groups. CMCS was grafted onto the surface of silica coated magnetic nanoparticles (MNPs) to obtain magnetically retrievable and deliverable antimicrobial nanoparticles (MNPs@CMCS). The presence of carboxylate groups in CMCS not only enhanced antimicrobial activity but also enabled Ag ions chelating ability to induce the in situ formation of Ag nanoparticles (AgNPs). The deposition of AgNPs on the surface of MNPs@CMCS could significantly increase its antimicrobial activity against planktonic cells due to the dual action of CMCS and AgNPs. Due to its high magnetism, the as-prepared MNPs@CMCS-Ag could be efficiently delivered into an existing biofilm under the guidance of an applied magnetic field. Without direct contact, the Ag ions and/or radical oxygen species (ROS) released from the deposited Ag nanoparticles could effectively kill the bacteria embedded in the extracellular polymeric substances (EPS) matrix of biofilm.

20 citations

Journal ArticleDOI
TL;DR: In this paper, deoxycholic acid carboxymethyl chitosan (DACMC) was synthesized via a two-step reaction, namely carboxy methylation and alkylation.
Abstract: In the present study, deoxycholic acid carboxymethyl chitosan (DACMC) was synthesised via a two-step reaction, namely carboxymethylation and alkylation. Fourier Transform Infrared (FTIR) Spectrometer, Proton Nuclear Magnetic Resonance (1H NMR) Spectrometer, Transmission Electron Microscope (TEM) and Thermogravimetric Analyser (TGA) were used to characterise DACMC. Spherical self-aggregates of DACMC micelles with the size ranging from 91.3 to 140.0 nm was observed. DACMC was soluble in pH range studied (1–13), except pH 4. DACMC micelles were formed at critical concentration (CMC) value of 0.468 mg/mL. The ability of DACMC to encapsulate and load rotenone was determined at different weight ratios. The highest value of encapsulation efficiency (EE%) (more than 98%) was obtained for weight ratio of 100:1 (DACMC:Rotenone). The in vitro release data of rotenone-loaded DACMC followed Ritger and Peppas Case II transport mechanism. Results from this study highlight the potential of DACMC to reduce organic solvent application in water-insoluble pesticide production.

6 citations

Journal ArticleDOI
TL;DR: In this paper, structural investigations have been carried out in powder processed polyvinylidene fluoride containing various amounts of titanium dioxide and lead monoxide as fillers, and the crystallinity was found to increase significantly at very low filler concentration (< 3 percent, while it decreased monotonically with increasing filler concentrations above 5 percent.
Abstract: Structural investigations have been carried out in powder processed polyvinylidene fluoride containing various amounts of titanium dioxide and lead monoxide as fillers. The crystallinity was found to increase significantly at very low filler concentration (<3 percent) while it decreased monotonically with increasing filler concentrations above 5 percent. The phase transformation in the crystal structure was also noticed especially after sintering and the formation of beta phase was favourable in samples containing lead oxide. These various findings were also confirmed by infrared absorption studies and explained on the basis of deformation of the polymer during compaction together with preferential nucleation by the filler during the sintering step of the powder processing technique.

2 citations


References
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Journal ArticleDOI
TL;DR: In this paper, the theory of transfer of charge from an electrified surface layer through the bulk of a dielectric is developed for transient space-charge-limited current conditions, and the modifications required when conduction is included and when diffusion is included are indicated.
Abstract: The theory of the transfer of charge from an electrified surface layer through the bulk of a dielectric is developed for transient space‐charge‐limited current conditions. The modifications required when conduction is included and when diffusion is included are indicated. Comparison with published data for polyethylene indicates carrier mobilities of the order of 10−11 cm2 V−1 sec−1 at room temperature.

95 citations

Book
01 Jan 1961

36 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the origin of relaxations in terms of trapping of charge carriers injected from the electrodes and discuss the nature of the electrodes, injecting as well as blocking types.
Abstract: Depolarization current characteristics of solution grown polyvinylfluoride (PVF) films have been studied, above room temperature as a function of the poling field (1.0 × 10 4 − 2.0 × 10 5 V / cm ) and the nature of the electrodes, injecting as well as blocking types. We discuss the origin of relaxations in terms of trapping of charge carriers injected from the electrodes.

7 citations