Internal radiotherapy in prostatic carcinoma; disappointing long-term results of retropubic Iodine-125 implantation

OBJECTIVE: To evaluate the results of retropubic implantation of 1-125 seeds in patients with carcinoma of the prostate. DESIGN: Retrospective study of records. SETTING: Netherlands Cancer Institute/Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands. METHOD: A retrospective study of records provided follow-up data on 75 patients treated in the period 1981-1990 with implantation of 1-125 seeds by a retropubic approach, preceded by pelvic lymph node dissection. Criteria for the treatment were: To, T1 or T2 carcinoma of the prostate, prostatic volume < 40 ml, no contraindications to surgery. RESULTS: The median follow-up was 103 (60-157) months. Four patients died of complications (5%). Major postoperative complications occurred in 23% (17/75) of the cases. Residual carcinoma or distant metastasization was encountered in 43 of the 71 patients (61%). Sixteen patients died from the consequences of the prostatic carcinoma. The 5- and 10-year survival rates amounted to 74% and 42%, respectively, the cancer-specific 5- and 10-year survival rates to 85% and 67%, respectively. At the latest check-up, 18 patients were alive with tumour, 16 of them under hormonal treatment, while 21 patients were alive without indications of active prostatic carcinoma. CONCLUSION: Treatment of carcinoma of the prostate with retropubic implantation of 1-125 seeds resulted in a high incidence of local therapeutic failure and numerous postoperative complications. These results are poorer than those of total prostatectomy and external radiotherapy.     

A mathematical model and experimental study of the electrodeposition of Ni---Cu alloys from complexing electrolytes

A mathematical model, predicting the influence of a citrate complexant in the electrodeposition of copper—nickel alloys, was developed. The model which takes into account the deposition of complexed and uncomplexed species is based on convective-diffusion transport and Butler—Volmer reaction kinetics. Cu---Ni alloys were electrodeposited onto a rotating cylinder electrode at different rotation rates from electrolytes containing different total citrate concentrations. The theoretical model was found to predict correctly the influence of experimental variables, such as citrate concentration and rotation rate on the polarization behavior, alloy composition and current efficiency. Increasing the total citrate concentration in the electrolyte resulted in a reduction of the electrochemical reaction rates, which is explained by the interactions between the complexed and uncomplexed reacting species.     

Combinatorial preparation and characterization of thin-film multilayer electro-optical devices

In this article we present a setup for the combinatorial vapor deposition of thin-film multilayer devices as well as methods for the fast and efficient analytic screening of the libraries obtained. The preparation setup is based on a commercially available evaporation chamber equipped with various evaporation sources for both organic and metallic materials. The combinatorial approach is realized by the combination of a rotation stage for the substrate, a five-mask sampler, and an additional mask whose position can be deliberately varied along one axis during the evaporation process. The latter is used to evaporate linear as well as step gradients by continuous or stepwise movement of a shutter mask. The mask sampler allows to define the sectors of the library and to evaporate more complex structures, e.g., an electrode layout. Finally, the simultaneous evaporation of two or more materials enables us to produce layers of varying composition ratio in general and doped materials, in particular. For the control of the evaporation process we have developed an automation software, which is particularly helpful for complex library designs and which grants excellent repeatability of experiments. Efficient and fast characterization of the obtained libraries is realized by (i) a purely optical setup and (ii) an electro-optical setup. (i) The UV/vis reader FLASHScan 530 permits to map out the UV/vis absorbance or fluorescence of the whole library. The UV/vis absorbance is primarily used to determine layer thicknesses and to confirm thickness uniformity across larger regions. The fluorescence measurements are used to determine the composition of layers containing fluorescent dyes. (ii) For a detailed short- and long-term electro-optical analysis we have developed an automated measurement system, which allows the characterization of 8x8 optoelectronic devices and to study their degradation behavior. Both solar cells and organic light-emitting diodes can be tested. Finally, we have developed a data analysis software to extract characteristic values from the huge amount of data and with this facilitate the finding of systematic dependencies.     

Elasticity of hexagonal liquid crystals

An investigation of the elastic properties of hexagonal phases of typical liquid crystal samples on an ordered hexagonal discotic hexa‐n‐octyloxytriphenylene (C₈HET), a disordered one a triphenylene hexa‐n‐dodecanoate (C₁₁HAT) and a hexacatenar phasmid was carried out. Characterization of their mechanical stability and analysis of light scattering were used; the same results were obtained for the three samples in spite of the differences in their molecular shapes and molecular orders in columns. From the instability of undulating columns submitted to a dilative strain normal to columns, we deduced an anomalously large value of the correlation length m (m ≈ 0.1 µm), compared to that of the smectic liquid crystals (m ≈ 20 Å). Results from depolarized Rayleigh scattering showed that, although consisting of one‐dimensional liquid‐like structures, the studied samples in their hexagonal phases behaved elastically like three‐dimensional solids. Considering the differences in molecular shapes and orders, this elastic behaviour was attributed to regular defects. Therefore, one can probably generalize this elastic behaviour as being due to the columnar hexagonal structure. © 2001 Society of Chemical Industry     

Determination of the Effective Properties of Thermal Spray Coatings Using 2D and 3D Models

Models, which are developed to determine the effective properties of thermal spray coatings, require the material properties of each constituent of the coating as well as the information about the spatial positions and the geometries of these constituents as input parameters. The complex microstructure of thermally sprayed Yttria-stabilized zirconia (YSZ) coatings consists of irregular voids which are distributed non-uniformly in the coating. It is a common practice in the literature to employ two-dimensional (2D) cross-sectional images of the coatings to derive the geometrical model of the microstructure and conduct the simulations in 2D. In the context of this study, contrary to the 2D approach, a new three-dimensional (3D) reconstruction approach has been developed to model the microstructure of thermally sprayed coatings in 3D. The effective properties of an YSZ coating have been calculated by means of asymptotic homogenization and virtual testing methods. The results of the models, which have been conducted in 2D and 3D, are compared with each other. Finally, the capabilities of these methods with respect to the modeling approach (in 3D and in 2D) are analyzed on the basis of reference measurements.     

Self-aligned silicon-on-insulator nano flash memory device

This paper reports on the fabrication of a silicon-on-insulator nano flash memory device based on the differential oxidation rate of silicon resulting from gradients in the arsenic doping concentration. The key processes involved are the formation of the desired arsenic doping profile, electron beam lithography and wet oxidation. The resulting device is a triangular-channel MOSFET with a nanocrystal floating gate embedded in the gate oxide. The length, width and height of the nanocrystal are 10, 10 and 20 nm, respectively. As long as the control gate voltage does not exceed ±2V, the device behaves like a thin and narrow P-channel MOSFET. When a voltage of −5 or +5 V is applied to the control gate at room temperature, holes are injected into the floating gate or removed from it, respectively. This effect induces a persistent shift of the threshold voltage of the device, which acts as a miniature EEPROM.