Ultra fast imaging NMR method for measuring fast transport processes in thin porous media

Measuring moisture distributions during fast transport processes in thin porous media is a challenging task. In this paper, Ultra Fast Imaging (UFI) NMR is proposed as a valuable measurement technique for investigating moisture uptake in porous media by achieving a temporal resolution of 10 ms and spatial resolution between 14.5 and 18 μm. This paper gives a detailed explanation about the methodology and the interpretation of the signal intensity. It is shown that there exist specific T 1- and T 2- relaxation time conditions for performing UFI experiments with signal-to-noise ratios that are sufficiently high. In most cases, a contrast agent is required to optimize these relaxation times and achieve the optimal measurement conditions. In the first part of this paper, both CuSO4 and Clariscan are discussed as possible contrast agents. Furthermore, it is shown that the signal intensity can be linked to the moisture content for water based liquids. The second part of this paper covers penetration experiments on porous PVDF membranes. These measurements show that the technique is able to measure moisture profiles during fast capillary penetration and allows to extract moisture front positions. Those front positions follow a linear time behavior in PVDF membranes. Lastly the NMR-measurements showed similar results when compared to scanning absorptometry (ASA). </p

Phase diagram for diblock copolymer melts under cylindrical confinement

We extensively study the phase diagram of a diblock copolymer melt confined in a cylindrical nanopore using real-space self-consistent mean-field theory. We discover a rich variety of new two-dimensional equilibrium structures that have no analog in the unconfined system. These include non-hexagonally coordinated cylinder phases and structures intermediate between lamellae and cylinders. We map the stability regions and phase boundaries for all the structures we find. As the pore radius is decreased, the pore accommodates fewer cylindrical domains and structural transitions occur as cylinders are eliminated. Our results are consistent with experiments, but we also predict phases yet to be observed.Comment: 12 pages, 3 figures. submitted to Physical Review Letter

Dynamics of cross linking fronts in alkyd coatings

The dynamics of the curing process of alkyd coatings is an important aspect for coating performance. The formation of cross links in an alkyd coating film has been followed in time using a microimaging nuclear magnetic resonance setup, having a spatial resolution of 5 µm perpendicular to the film. During this cross-linking process a front has been observed inside the coating film. The position of this front varied with the square root of time. With the help of a simple reaction model, we have proven that this dynamics results from the fact that the curing rate is limited by the oxygen flux into the coating. This model can also explain, the differences in curing rates observed for various coatings. © 2005 American Institute of Physics

Four cycles of BEP versus an alternating regime of PVB and BEP in patients with poor-prognosis metastatic testicular non-seminoma; a randomised study of the EORTC Genitourinary Tract Cancer Cooperative Group.

We have investigated whether an alternating induction chemotherapy regimen of PVB/BEP is superior to BEP in patients with poor-prognosis testicular non-seminoma. A total of 234 eligible patients were randomised to receive an alternating schedule of PVB/BEP for a total of four cycles or four cycles of BEP. Poor prognosis was defined as any of the following: lymph node metastases larger than 5 cm, lung metastases more than four in number or larger than 2 cm, haematogenic spread outside the lungs, such as in liver and bone, human chorionic gonadotrophin > 10,000 IU l-1 or alphafetoprotein > 1000 IU l-1. The complete response (CR) rates to PVB/BEP and BEP were similar, 76% and 72% respectively (P = 0.58). In addition, there was no significant difference in relapse rate, disease-free and overall survival at an average follow-up of 6 years. The 5-year progression-free and survival rates in both treatment groups were approximately 80%. The PVB/BEP regime was more toxic with regard to bone marrow function; the frequencies of leucocytes below 1000 microliters-1, leucocytopenic fever and platelets below 25,000 microliters-1, throughout four cycles were 28% vs 5% (P < 0.001), 16% vs 5% (P = 0.006), and 10% vs 1% (P = 0.001) respectively. Neuropathy also occurred more often in the PVB/BEP arm: 47% vs 25% (P = 0.001). This study shows that an alternating regimen of PVB/BEP is not superior to BEP and that it is more myelo- and neurotoxic

How ions distribute in a drying porous medium: A simple model

Salt crystallization at surfaces is an important problem for buildings and monuments. We do not consider the formation of salt crystals as such, but focus on transport properties of ions in a drying porous medium. We deal with the first phase of the drying process, where the water is still uniformly distributed throughout the medium. An approximate model is presented, which accounts for both convection and diffusion. It is shown that the key parameter is the Peclet number at the evaporating surface, PehL/D, where h, L, , and D are the drying rate, sample size, porosity, and diffusion constant, respectively. When Pe1 (diffusion dominates over convection) the ions remain uniformly distributed throughout the system. Strong accumulation at the evaporating surface occurs for Pe1 (convection dominates over diffusion). Crossover behavior is found for Pe1. Therefore, it is likely that the first crystals will be formed both in the bulk and at the interfaces of the material when Pe1. For high values of Pe the density peak at the evaporating surface will reach the saturation concentration long before it is reached in the bulk of the material. As a consequence, the salt starts to crystallize at the interfaces

A phase II study of raltitrexed and gemcitabine in patients with advanced pancreatic carcinoma

Advanced adenocarcinoma of the pancreas has a very poor prognosis. The aim of this study was to assess the efficacy and tolerability of a combination of the chemotherapeutic agents gemcitabine and raltitrexed. Chemonaïve patients with advanced adenocarcinoma of the pancreas were treated with a combination of raltitrexed (3.5 mg m−2 on day 1 of a 21-day treatment cycle) and gemcitabine (800 mg m−2 intravenously (i.v.) on days 1 and 8 of a 21-day cycle). Between April 2000 and February 2003, 27 patients were enrolled onto the study. The mean duration of treatment was 11 weeks. Four of 27 patients experienced at least one episode of grade 3 or 4 neutropenia. One patient with grade 4 neutropenia died due to sepsis. Four of 27 patients experienced grade 4 diarrhoea. There was one partial remission (4%) and 12 patients experienced disease stabilisation (44%). The 6-month and 1-year survival rates were 37 and 11%, respectively. Symptomatic benefit occurred in seven (26%) patients. We conclude that a combination of raltitrexed and gemcitabine, using the schedule and doses in this study, cannot be recommended for patients with advanced pancreatic cancer

Serum alpha-fetoprotein surge after the initiation of chemotherapy for non-seminomatous testicular cancer has an adverse prognostic significance.

It has been recognized that the tumour markers alpha-fetoprotein (AFP) and human chorionic gonadotrophin (HCG) may show a transient elevation after the initiation of chemotherapy in non-seminomatous testicular cancer. We investigated the prognostic importance of these so-called marker surges in a cohort of patients treated with cisplatin combination chemotherapy between 1983 and 1991. A total of 669 patients were studied. Of 352 patients who had an elevated AFP at the start of treatment and for whom we had data at both day 1 and day 8, 101 (29%) had a surge. Of 317 patients for whom we had data for HCG, 80 patients (25%) had a surge. It was found that an AFP surge was a strong adverse prognostic factor for progression [hazard ratio (HR) 2.28, P=0.005]. There was no statistically significant difference in survival (HR 1.65, P=0.13). There was no prognostic significance of a HCG surge, either for progression or for survival. To investigate whether a surge was an independent prognostic factor for progression and survival, multivariate Cox regression models were fitted using the independent prognostic factors for progression and survival and the surge/decline variable. An AFP surge was retained in the final model for progression. A HCG surge was of no prognostic importance for progression or survival. We conclude that an AFP surge has an adverse prognostic significance, independent of pretreatment characteristics