No abstract available

[en] The fluorescence and absorption spectra of Eu³⁺ in K₅Eu(MoO₄)₄ have been measured at 300 K and 77 K. The fluorescence lifetime of the ⁵D₀ state is 1.4 ms at 300 K. The largest cross section sigma(⁵D₀→⁷F₂(4))= 1.3x10^-21cm² and the removal of degeneracies require to replace the nearest neighbour Dsub(3d) symmetry of Eu³⁺ by the effective symmetries C₁, C₂ and Csub(s) of the whole unit cell. It is shown that C₁ dominates because of the statistical distribution of K⁺ and Eu³⁺. The corresponding inhomogeneous broadening is observed at 77 K. (Auth.)

No abstract available

[en] The transient photoluminescence decay (PLD) is investigated as a technique for the quality control of GaAs solar cells. An analytic expression for the PL intensity is derived from the time dependent continuity equation for minority carrier concentration in the emitter by the Fourier transform method. On both sides of the emitter, i.e. at the interface to the window layer and to the space charge region, surface recombination velocities that can vary between 0 and ∞ are allowed as boundary conditions. Experiments were performed using a mode-locked and cavity dumped laser as excitation source and an optical sampling oscilloscope as detector for the transient PL. PLD from GaAs wafers and solar cells was measured with time resolution of down to 20 ps for various intensities of laser excitation and (for the cells) under open-circuit and short-circuit condition. The results are discussed in respect to the theory together with a model of local internal boundary conditions at the junction near the exciting laser beam

[en] The transfusion of allogenic, in vitro expanded natural killer cells (NKC) is a novel therapy option in oncology. To date, however, the biodistribution and kinetics of allogenic NKC have not been investigated. Therefore, in this study three patients with renal cell carcinoma received 3-7 x 10⁸ NKC labelled with indium-111 oxine with a tenfold excess of unlabelled cells during NKC therapy. Whole-body scintigrams were obtained (0.5-144 h) in the anterior and posterior views. Scintigrams were analysed using a region of interest technique, and single-photon emission tomography (SPET) studies of the abdomen were performed. Results were compared to those obtained with polymerase chain reaction (PCR) of the peripheral blood (determination of foreign DNA, nested PCR, limit of detection 0.01%). Shortly after transfusion of NKC, more than 50% of the activity was accumulated in the lungs. We observed redistribution effects from lungs to liver, spleen and bone marrow. No significant loss of activity could be detected. In two of four large metastases, tracer accumulation could be proven by SPET. As confirmed by scintigrams and PCR, the fraction of circulating transfused cells was low at all times. Long-term activity retention might be caused either by survival of the allogenic cells, as confirmed by PCR (up to 3 days p.i.), or by phagocytosis of labelled cellular fragments. However, PCR data and uptake in metastases indicated long survival of a portion of allogenic NKC. Such long survival and low retention of the cells in the lung are requirements for an effective immunotherapeutic approach. (orig.)

[en] Crystalline silicon thin-film solar cells (CSITF; high temperature approach) on low-cost substrates will only get their chance on the market when they can be introduced into an industrial solar cell process. Therefore, a conductive diffusion barrier intermediate layer (IL) is necessary. The most promising candidate is, in our opinion, SiC. Not just because doping with boron or phosphorous can change the electrical behavior effectively. It also matches well in thermal expansion coefficients with RBSiC (reaction-bonded) ceramics which is a very promising low-cost substrate. The passivation performance and the possibility to use the thin layer as a dopant source for an in situ back surface field are additional benefits. In this paper, we will show that the electrical conductivity of SiC can become sufficiently high with temperature treatments. We will furthermore present FTIR and SIMS measurements which would give information about the changing of bonding conditions and the distribution of the dopant boron with different deposition temperatures and annealing

[en] To reduce potential mis-registration from differences in the breathing pattern between two complementary PET and CT data sets, patients are generally allowed to breathe quietly during a dual-modality scan using a combined PET/CT tomograph. Frequently, however, local mis-registration between the CT and the PET is observed. We have evaluated the appearance, magnitude, and frequency of respiration-induced artefacts in CT images of dual-modality PET/CT studies of 62 patients. Combined PET/CT scans during normal respiration were acquired in 43 subjects using single- or dual-slice CT. Nineteen patients were scanned with a special breathing protocol (limited breath-hold technique) on a single-slice PET/CT tomograph. All subjects were injected with 370 MBq of FDG, and PET/CT scanning commenced 1 h post injection. The CT images were reconstructed and, after appropriate scaling, used for on-line attenuation correction of the PET emission data. We found that respiration artefacts can occur in the majority of cases if no respiration protocol is used. When applying the limited breath-hold technique, the frequency of severe artefacts in the area of the diaphragm was reduced by half, and the spatial extent of respiration-induced artefacts was reduced by at least 40% compared with the acquisition protocols without any breathing instructions. In conclusion, special breathing protocols are effective and should be used for CT scans as part of combined imaging protocols using a dual-modality PET/CT tomograph. The results of this study can also be applied to multi-slice CT to potentially reduce further breathing artefacts in PET/CT imaging and to improve overall image quality. (orig.)

[en] Introduction: Tumor refractoriness to chemotherapy is frequently due to the acquisition of resistance. Resistant cells selected by exposure to chemotherapy agents may exhibit differences in [¹⁸F]fluoro-2-deoxy-D-glucose (FDG) incorporation, as compared with sensitive cells. Methods: FDG incorporation, hexokinase (HK) activity, glucose transport and ATP content were determined in clones of 5-fluorouracil (5FU)-resistant MCF7 cells, established by long-term exposure to increasing 5FU concentrations, and in parental MCF7 cells. Results: FDG incorporation was decreased in MCF7 cells resistant to 5FU; HK activity was similar in the resistant and sensitive cells, while glucose transport was increased, as compared with sensitive cells. Treatment of cells with the glucose efflux inhibitor phloretin increased FDG incorporation to similar levels in the resistant and sensitive cells. Analysis of microarray data demonstrated the expression of GLUT1, 8 and 10 transporters in MCF7 cells. GLUT8 and 10 expression was decreased in the resistant cells, while GLUT1 was only increased in cells resistant to the lowest 5FU concentration. Conclusion: FDG incorporation in 5FU-resistant MCF7 cells is decreased, as compared with sensitive cells. Our findings also suggest that this may be due to high rates of membrane glucose transport in the resistant cells resulting in enhanced efflux of FDG. We believe that this is the first demonstration that facilitative glucose transporters can actually decrease the incorporation of FDG

[en] Conventional chemotherapy of cancer has its limitations, especially in advanced and disseminated disease and suffers from lack of specificity. This results in a poor therapeutic index and considerable toxicity to normal organs. Therefore, many efforts are made to develop novel therapeutic tools against cancer with the aim of selectively targeting the drug to the tumour site. Drug delivery strategies fundamentally rely on the identification of good-quality biomarkers, allowing unequivocal discrimination between cancer and healthy tissue. At present, antibodies or antibody fragments have clearly proven their value as carrier molecules specific for a tumour-associated molecular marker. This present review draws attention to the use of near-infrared fluorescence (NIRF) imaging to investigate binding specificity and kinetics of carrier molecules such as monoclonal antibodies. In addition, flat-panel volume computed tomography (fpVCT) will be presented to monitor anatomical structures in tumour mouse models over time in a non-invasive manner. Each imaging device sheds light on a different aspect; functional imaging is applied to optimise the dose schedule and the concept of selective tumour therapies, whereas anatomical imaging assesses preclinically the efficacy of novel tumour therapies. Both imaging techniques in combination allow the visualisation of functional information obtained by NIRF imaging within an adequate anatomic framework.

[en] Introduction: 5-[¹⁸F]Fluoro-5-deoxyribose ([¹⁸F]FDR) 3 was prepared as a novel monosaccharide radiotracer in a two-step synthesis using the fluorinase, a C-F bond forming enzyme, and a nucleoside hydrolase. The resulting [¹⁸F]FDR 3 was then explored as a radiotracer for imaging tumours (A431 human epithelial carcinoma) by positron emission tomography in a mice model. Methods: 5-[¹⁸F]Fluoro-5-deoxyribose ([¹⁸F]FDR) 3, was prepared by incubating S-adenosyl-L-methionine (SAM) and [¹⁸F]fluoride with the fluorinase enzyme, and then incubating the product of this reaction, [¹⁸F]-5'-fluoro-5'-deoxadenosine ([¹⁸F]FDA) 2, with an adenosine hydrolase to generate [¹⁸F]FDR 3. The enzymes were freeze-dried and were used on demand by dissolution in buffer solution. The resulting [¹⁸F]FDR 3 was then administered to four mice that had tumours induced from the A431 human epithelial carcinoma cell line. Results: The tumour (A431 human epithelial carcinoma) bearing mice were successfully imaged with [¹⁸F]FDR 3. The radiotracer displayed good tumour imaging resolution. A direct comparison of the uptake and efflux of [¹⁸F]FDR 3 with 2-[¹⁸F]fluoro-2-deoxyglucose ([¹⁸F]FDG) was made, revealing comparative tumour uptake and imaging potential over the first 10–20 min. The study revealed however that [¹⁸F]FDR 3 does not accumulate in the tumour as efficiently as [¹⁸F]FDG over longer time periods. Conclusions: [¹⁸F]FDR 3 can be rapidly synthesised in a two enzyme protocol and used to image tumours in small animal models