In-vitro combination of arsenic trioxide and chemotherapy in small-cell lung cancer

published_or_final_versionThe 15th Medical Research Conference, Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 66, abstract no. 11

Phthalocyanine based Schottky solar cells

Phthalocyanine (Pc) materials are commonly used in organic solar cells. Four different phthalocyanines, nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), iron phthalocyanine (FePc), and cobalt phthalocyanine (CoPc) have been investigated for organic solar cell applications. The devices consisted of indium tin oxide (ITO) coated glass substrate, Pc layer, and aluminum (Al) electrode. It has been found that ITO/CuPc/Al Schottky cell exhibits the best performance. To investigate the influence of the active layer thickness on the cell performance, cells with several different thicknesses were fabricated and optimal value was found. Schottky cell exhibits optimal performance with one ohmic and one barrier contact. However, it is suspected that ITO/CuPc contact is not ohmic. Therefore, we have investigated various ITO surface treatments for improving the performance of CuPc based Schottky solar cell. We have found that cell on ITO treated with HCl and UV-ozone exhibits the best performance. AM1 power conversion efficiency can be improved by 30% compared to cell made with untreated ITO substrate. To improve power conversion efficiency, double or multilayer structure are required, and it is expected that suitable ITO treatments for those devices will further improve their performance by improving the contact between ITO and phthalocyanine layer.published_or_final_versio

Nanocomposite solar cells - Influence of particle concentration, size and shape on the device performance

Solar cells based on poly(3-hexylthiophene) (P3HT) :TiO2 nanocomposite films were investigated. We studied the influence of the nanoparticle concentrations and different nanostructures (spherical particles with size ∼5 nm and ∼20-40 nm, and rods with diameter ∼10 nm and length ∼40 nm) on the performance of the nanocomposite solar cells. PL quenching and improved external quantum efficiency (EQE) was observed for all the nanocomposite devices compared to that of pristine P3HT solar cells. However, TiO2 (∼5 nm spheres) and TiO2 rods showed only small improvement in EQE. The small improvement for the 5 nm TiO 2 spheres was attributed to the lack of connectivity of nanoparticles for electron conduction. Therefore, the charge collection efficiency was limited. For TiO2 rods, the tendency of the rods to lie in the plane of substrates also limited the charge conduction and collection in the direction perpendicular to the substrates. Therefore, the improvement of the devices made by these nanoparticles was limited. For TiO2 (20-40 nm spheres) with optimal concentration, external quantum efficiency up to 15% and AM1 power conversion efficiency of 0.42% were obtained. The improvement in the efficiency was related to the improved morphology of the film and was attributed to the formation of percolation paths of TiO2 for electron conduction.published_or_final_versio

Indium-tin-oxide surface treatments: Influence on the performance of CuPc/C60 solar cells

The performance of organic solar cells was influenced by different indium tin oxide (ITO) surface treatments. The uses of Hall measurements, Seebeck coefficient measurements, surface sheet measurements, and surface probe microscopy to characterize ITO sustrates were discussed. The parameters of ITO such as work function, carrier concentration, sheet resistance and surface roughness were changed due to the surface treatments.published_or_final_versio

Influence of the device architecture to the ITO surface treatment effects on organic solar cell performance

In this work, we investigate the influence of different indium tin oxide (ITO) surface treatments on the performance of organic solar cells with different device architectures. Two layer cells with different layer hierarchy (ITO/copper phthalocyanine (CuPc)/fullereve (C60/Al and ITO/C 60/CuPc/Cu) and three layer cells with mixed layer inserted between CuPc and C60 were fabricated. We found that in all cases the short circuit current was the parameter which was most significantly affected by ITO surface treatment. However, the performance of the cells with C60 layer in contact with ITO was markedly less sensitive to the ITO surface treatments compared to the cells with CuPc in contact with ITO. The cells with C60 layer in contact with ITO also exhibited higher efficiency compared to the cells with CuPc in contact with ITO. We also fabricated two layer cells with structures ITO/CuPc/perylene tetracarboxylic acid diimide (PTCDI)/Al and ITO/PTCDI/CuPc/Cu. In this case, we also obtain higher efficiency and lower sensitivity to ITO properties when "n type" material is in contact with ITO. The best obtained AMI power conversion efficiency was 0.4% for ITO/PTCDI/CuPc/Cu cell and ITO/C60/CuPc:C60/CuPc/Cu cells.published_or_final_versio

Prognostic Value of 18 F-FDG PET-CT in Nasopharyngeal Carcinoma: Is Dynamic Scanning Helpful?

published_or_final_versio

Accuracy and sensitivity of four-dimensional dose calculation to systematic motion variability in stereotatic body radiotherapy (SBRT) for lung cancer

published_or_final_versio

Evolution of optical properties of tris (8-hydroxyquinoline) aluminum (Alq3) with atmosphere exposure

Tris (8-hydroxyquinoline) aluminum (Alq3) represents a material of significant interest for electron transport and/or light emitting layer applications in organic light emitting diodes (OLEDs). In spite of advances in Alq3 based devices, the knowledge and understanding of the optical properties of Alq3 and its chemical and environmental stability is still limited. With the reports of decreased turn-on voltage and increased efficiency of OLEDs, the issues of lifetime and stability of those devices are attracting increasing attention. The degradation of Alq3 based OLEDs and dark spots formation and growth have been intensively studied. The studies on degradation of optical properties of Alq3 itself remain scarce. We have investigated effects of atmosphere exposure to properties of tris (8-hydroxyquinoline) aluminum (Alq3) thin films by photoluminescence (PL) and absorption measurements. Alq3 films were evaporated on glass substrates at different temperatures. The influence of annealing to the environmental stability of the films has also been investigated. It has been found that deposition at higher substrate temperature and annealing of the samples deposited at room temperature yields improvement in environmental stability of the films, i.e. less decrease of the PL intensity over time with atmosphere exposure, as well as increased PL intensity. To investigate further effects of the air exposure, films deposited at room temperature were stored for four days in air, nitrogen, and oxygen. No decrease in PL intensity has been found for storage in nitrogen, while decrease for the film stored in oxygen was smaller than that for film stored in air, indicating that both humidity and oxygen play a role in PL intensity decrease in Alq3 thin films.published_or_final_versio

Fabrication of Photovoltaic Cell From Rhenium Containing Polymer

Photovoltaic devices were fabricated using rhenium bis(arylimino) acenaphthene (DIAN) complex containing poly(p-phenylenevinylene). These polymers absorb strongly in the visible region at ca. 440-550 nm. In addition, this type of transition metal based polymers have been shown to exhibit large photo-sensitivity due to the presence of the rhenium complex, which has a relatively long-lived Metal-to-Ligand Charge Transfer (MLCT) character. By using this type of polymers, the metal content can be adjusted easily by simply changing the monomer feed ratio. Moreover, the excited state properties and electronic absorption properties can be modified by varying the structure of the diimine ligand coordinated to the metal. This approach allows us to fine-tune the absorption spectra of the polymers by employing different types of rhenium complex derivatives. PEDOT:PSS and PTCDI were used as the hole and electron transport layers, respectively. The ITO/PEDOT:PSS/DIAN-PPV/PTCDI/Al devices were found to exhibit photovoltaic response under the illumination of AMI solar radiation. The short-circuit current ISC, open-circuit voltage V OC, and the fill factor FF were measured to be 38 μA/cm 2, 0.93 V and 0.21 respectively. Another photovoltaic device was prepared with the structure ITO/PEDOT:PSS/DIAN-PPV:TiO2/PTCDI/Al and its photovoltaic properties were studied. The presence of TiO2 will assist the electron transport of the DIAN-PPV to the PTCDI, in which the electrons can be collected at the aluminium electrode. The short-circuit current ISC open-circuit voltage VOC, and the fill factor FF were measured to be 51 μA/cm2, 1.18 V and 0.12 respectively. It was observed that the power conversion efficiency of photovoltaic devices related closely to the rhenium content and the structure of the rhenium complex used.published_or_final_versio

Comparing the sensitivity of ionization chamber array to film and point dose measurement for IMRT delivery errors

Abstract no. 10625Therapy General Poster Discussion: SU‐FF‐T‐226PURPOSE: To compare the sensitivity of 2D ion chamber array, film dosimetry and point dose measurement for detecting IMRT delivery errors. METHOD AND MATERIALS: 2 types of IMRT delivery errors were considered. First type involved adding 1 mm systematic error to 1 bank of the MLC leaves, resulting in a dose discrepancy of ≥ 5%. The second type involved ‘undeliverable intensity patterns’, resulting from improper use of smoothness constraint during optimization. 4 and 2 plans were studied for type 1 and …postprin