The incremental stiffness of an assembly of particles

Summary The problem of fairly densily packed particles with rate independent though otherwise arbitrary interaction is investigated in two dimensions. It is shown that slow changes in a statistically uniform medium in the pre-failure deformation state can be described by a stiffness tensor. An approximate expression for this tensor is obtained from first principles. The connection with the perfectly random heterogeneous medium is established. A simple example for round rough particles in an isotropic packing of four contacts is given.With 8 Figure     

Intercomparison of scanning probe microscopes

Comparison measurements on reference standards are reported in which 13 partners with different instruments took part. A set of prototype standards which had been produced and calibrated within a European project were used for the measurements. Here, results of measurements on a 240 nm step height standard and a two-dimensional lateral standard with a nominal pitch of 1 μm are reported.     

Flow equations of particle fluid mixtures

Summary A set of flow equations are derived for the velocity components of the solid and liquid phases of a particle fluid mixture. The equations have a limited validity to the case of uniaxial flow accompanied by radial expansion.The Terzaghi fluidization criterion is used to fix an internal parameter in the equations. Using a stability analysis it is demonstrated that the process of the onset of fluidization is accompanied by a smoothing out of internal heterogeneity in the system.The applications treated are the permeability of a densely packed material and the settlement of a geotechnical filter.     

Transport processes during electrowashing of filter cakes

Applications of electric fields during washing of filter cakes increases the removal rate of ions from the cake mother liquor, and under appropriate conditions the field also increases the wash flow rate by electroosmosis. Experimental data that show the key effects of the fields on the rates of ion mass transfer are presented: with the downstream electrode acting as a cathode, cation removal rates are increased whilst the removal rate of the anions is decreased. The concentration profile of the cations with washing time shows an increase in concentration to a value above that of the mother liquor, before it decreases due to displacement by the fresh wash liquor. A model is formulated that describes the advection, dispersion, ion migration and electroosmosis transport processes in the cake. Numerical solution of the model gives cation concentration profiles at the exit of the cake that are in qualitative agreement with the experimental observations. Experimentally measured wash liquor flow rates tend to be lower than what traditional colloid science principles predict by a factor of 5-10: reasons for this difference, supported by experimental work from other researchers, are discussed.     

Investigation of blind tip estimation

In this work we study functions for maximum likelihood estimation in blind tip estimation. We will implement the expectation maximization (EM), the stochastic EM, and stochastic approximation EM algortithms to estimate the unknown tip geometry. To demonstrate the functionality of the algorithms we applied it to dilated artificial input signal.     

Dosimetric analysis of chimeric monoclonal antibody cMOv18 IgG in ovarian carcinoma patients after intraperitoneal and intravenous administration

In this study the potential of intraperitoneal (i.p.) and intravenous (i.v.) administration of chimeric iodine-131-labelled MOv18 IgG for radioimmunotherapy was determined. The dosimetry associated with both routes of administration of cMOv18 IgG was studied in patients. Eight patients suspected of having ovarian carcinoma received 150 MBq 131I-cMOv18 IgG i.p. Blood and urine were collected and serial gamma camera images were acquired. Another group of four patients received 7.5 MBq 131I-cMOv18 IgG i.v. For all patients, tissue biopsies were obtained at surgery. Activity in the blood after i.p. administration was described by a bi-exponential curve with a mean uptake and elimination half-life of 6.9+/-3.2 h and 160+/-45 h, respectively. For i.v. infusion the mean half-life for the elimination phase was 103+/-12 h. Cumulative excretion in the urine was 17%+/-3% ID and 21%+/-7% ID in 96 h for i.p. and i.v. administration, respectively. Scintigraphic images after i.p. administration showed accumulation in ovarian cancer lesions, while all other tissues showed decreasing activity with time. Tumour uptake determined in the ovarian cancer tissue specimens ranged from 3.4% to 12.3% ID/kg for i.p. administration and from 3.6% to 5.4% ID/kg for i.v. administration. Dosimetric analysis of the data indicated that 1.7-4.3 mGy/MBq and 1.7-2.2 mGy/MBq can be guided to solid or ascites cells after i.p. and i.v. administration, respectively. Assuming that an absorbed dose to the bone marrow of 2 Gy will be dose limiting, a total activity of 4.1 GBq 131I-cMOv18 IgG can be administered safely via the i.p. route and 3.5 GBq via the i.v. route. At this maximal tolerated dose, a maximum absorbed dose to 1-g tumours in the peritoneal cavity of 18 and 8 Gy can be reached after i.p. and i.v. administration, respectively. For the i. p. route of administration, dose estimates for the tumour are even higher when the electron dose of the peritoneal activity is also taken into account: total doses to the tumour of 30 Gy and 22 Gy will be absorbed at the tumour surface and at 0.2 mm depth, respectively. In conclusion, therapeutic tumour doses can be achieved with 131I-cMOv18 IgG in patients with intraperitoneal ovarian cancer lesions with no normal organ toxicity. The i.p. route of administration seems to be preferable to i.v. administration.     

Genome-Wide Investigation of Multifocal and Unifocal Prostate Cancer—Are They Genetically Different?

Prostate cancer is widely observed to be biologically heterogeneous. Its heterogeneity is manifested histologically as multifocal prostate cancer, which is observed more frequently than unifocal prostate cancer. The clinical and prognostic significance of either focal cancer type is not fully established. To investigate prostate cancer heterogeneity, the genetic profiles of multifocal and unifocal prostate cancers were compared. Here, we report observations deduced from tumor-tumor comparison of copy number alteration data of both focal categories. Forty-one fresh frozen prostate cancer foci from 14 multifocal prostate cancers and eight unifocal prostate cancers were subjected to copy number variation analysis with the Affymetrix SNP 6.0 microarray tool. With the investigated cases, tumors obtained from a single prostate exhibited different genetic profiles of variable degrees. Further comparison identified no distinct genetic pattern or signatures specific to multifocal or unifocal prostate cancer. Our findings suggest that samples obtained from multiple sites of a single unifocal prostate cancer show as much genetic heterogeneity and variability as separate tumors obtained from a single multifocal prostate cancer.     

Moisture flow by micro structural contraction

Material properties of building and construction elements are requested to last for an increasingly longer service life. For cementitious materials in particular, the “birth” of these properties emerge at the early stage of the hardening process. It is the development of the microstructure that determines the load bearing capacity as well as the quality in the material in the future. The quality of the microstructure realized at early ages with this affect the performance of a structures current and futures performance. As research areas focus more and more on micro-structural densification and durability related issues, deformational changes become increasingly decisive for a high quality guarantee.When considering the different research levels of concrete, the multi-scale modelling approach can be considered. When considering the paste captured in between two aggregate particles, the ribbon-model can be applied to simulate the hardening behaviour of this piece of paste.The article shows numerical simulations about the effect of capillary water expelled from the microstructure due to syneresis processes on the one hand and contraction of the microstructure due to hardening shrinkage on the other. Simulations of cement pastes, composed of different water/cement ratios, clearly demonstrate a movement of capillary water throughout the microstructures and its influencing on shrinkage. The simulation results show a slight influence of syneresis on water expulsion and on the deformation of the ribbon-paste.     

The effect of lyophilization on steroid receptor behavior, as defined by sucrose density gradient analysis

The effects of lyophilization of both cytosol and tissue powder were examined by sucrose density gradient analysis (SDGA) of uterine estrogen receptor (ER) and progesterone receptor (PgR) from pig and calf. Cytosol prepared from lyophilized material (both cytosol and tissue powder) was compared to that prepared concomitantly from frozen, pulverized powders of the same tissue. It was found that both ER and PgR responses to SDG ionic strength and the ability of ER to demonstrate temperature-dependent 4S leads to 5S transformation were unimpaired by lyophilization. In addition, lyophilized cytosol and lyophilized tissue powder gave equivalent results. A few experiments examining lyophilization effects on steroid receptors from human breast biopsies did note some diminution of the 8S form of both ER and PgR following lyophilization, although this effect was variable in extent. It is nevertheless concluded that much lyophilized material exhibits many of the same responses as frozen, and may be used in lieu of the latter, at least within the confines of the parameters described here.