Studies on the Kinetics of very Rapid Cooling in Different Quenching Liquids- Application to Some Alloys of Iron, Nickel and Carbon

0NE can set the problem of quenching metals and alloys in the following manner. Let us consider a structural transformation arising in the metal or alloy within a certain interval of temperature 01, 02. Let its suppose that this transformation, without induction period, has an initial speed characterized by finite values at all the temperatures within the interval 01, 02, and by negligible value, at the boundaries 01 and 02 of this interval. This speed of transformation can be measured for all the temperatures within the interval 01, O2 by recording, against time, the variations of a physical property of the sample in direct relation with its structure.With the well-known isothermal thermodilatometer of Prof. Cheve-narci, this physical property is the length of a cylin-drical wire of some millimetres in diameter and 50 millimetres in length

Characterization of the glass transition in vitreous silica by temperature scanning small-angle X-ray scattering

The temperature dependence of the x-ray scattering in the region below the first sharp diffraction peak was measured for silica glasses with low and high OH content (GE-124 and Corning 7980). Data were obtained upon scanning the temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements resolve, for the first time, the hysteresis between heating and cooling through the glass transition for silica glass, and the data have a better signal to noise ratio than previous light scattering and differential thermal analysis data. For the glass with the higher hydroxyl concentration the glass transition is broader and at a lower temperature. Fits of the data to the Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very strong glass. The temperature derivative of the observed X-ray scattering matches that of light scattering to within 14%.Comment: EurophysicsLetters, in pres

Swinging of red blood cells under shear flow

We reveal that under moderate shear stress (of the order of 0.1 Pa) red blood cells present an oscillation of their inclination (swinging) superimposed to the long-observed steady tanktreading (TT) motion. A model based on a fluid ellipsoid surrounded by a visco-elastic membrane initially unstrained (shape memory) predicts all observed features of the motion: an increase of both swinging amplitude and period (1/2 the TT period) upon decreasing the shear stress, a shear stress-triggered transition towards a narrow shear stress-range intermittent regime of successive swinging and tumbling, and a pure tumbling motion at lower shear stress-values.Comment: 4 pages 5 figures submitted to Physical Review Letter

In situ measurements of density fluctuations and compressibility in silica glass as a function of temperature and thermal history

In this paper, small-angle X-ray scattering measurements are used to determine the different compressibility contributions, as well as the isothermal compressibility, in thermal equilibrium in silica glasses having different thermal histories. Using two different methods of analysis, in the supercooled liquid and in the glassy state, we obtain respectively the temperature and fictive temperature dependences of the isotheraml compressibility. The values obtained in the glass and supercooled liquid states are very close to each other. They agree with previous determinations of the literature. The compressibility in the glass state slightly decreases with increasing fictive temperature. The relaxational part of the compressibility is also calculated and compared to previous determinations. We discussed the small differences between the different determinations

Discovery Prospects for a Supernova Signature of Biogenic Origin

Approximately 2.8 Myr before the present our planet was subjected to the debris of a supernova explosion. The terrestrial proxy for this event was the discovery of live atoms of 60Fe in a deep-sea ferromanganese crust. The signature for this supernova event should also reside in magnetite Fe3O4 microfossils produced by magnetotactic bacteria extant at the time of the Earth-supernova interaction, provided the bacteria preferentially uptake iron from fine-grained iron oxides and ferric hydroxides. Using estimates for the terrestrial supernova 60Fe flux, combined with our empirically derived microfossil concentrations in a deep-sea drill core, we deduce a conservative estimate of the ^{60}{Fe} fraction as 60Fe/Fe ~ 3.6 x 10^{-15}. This value sits comfortably within the sensitivity limit of present accelerator mass spectrometry capabilities. The implication is that a biogenic signature of this cosmic event is detectable in the Earth's fossil record.Comment: As it appears in Icaru

Pattern Stability and Trijunction Motion in Eutectic Solidification

We demonstrate by both experiments and phase-field simulations that lamellar eutectic growth can be stable for a wide range of spacings below the point of minimum undercooling at low velocity, contrary to what is predicted by existing stability analyses. This overstabilization can be explained by relaxing Cahn's assumption that lamellae grow locally normal to the eutectic interface.Comment: 4 pages, 5 eps figure

Determination of an optimal response cut-off able to predict progression-free survival in patients with well-differentiated advanced pancreatic neuroendocrine tumours treated with sunitinib: an alternative to the current RECIST-defined response.

BACKGROUND: Sunitinib prolongs progression-free survival (PFS) in patients with advanced pancreatic neuroendocrine tumours (pNET). Response Evaluation Criteria in Solid Tumors (RECIST)-defined partial responses (PR; classically defined as ⩾30% size decrease from baseline) are infrequent. METHODS: Individual data of pNET patients from the phase II [NCT00056693] and pivotal phase III [NCT00428597] trials of sunitinib were analysed in this investigator-initiated, post hoc study. The primary objective was to determine the optimal RECIST (v.1.0) response cut-off value to identify patients who were progression-free at 11 months (median PFS in phase III trial); and the most informative time-point (highest area under the curve (AUC) by receiver operating characteristic (ROC) analysis and logistic regression) for prediction of benefit (PFS) from sunitinib. RESULTS: Data for 237 patients (85 placebo; 152 sunitinib (n=66.50 mg \u274-weeks on/2-weeks off\u27 schedule; n=86 \u2737.5 mg continuous daily dosing (CDD)\u27)) and 788 scans were analysed. The median PFS for sunitinib and placebo were 9.3 months (95% CI 7.6-12.2) and 5.4 months (95% CI 3.5-6.01), respectively (hazard ratio (HR) 0.43 (95% CI 0.29-0.62); P CONCLUSIONS: A 10% reduction within marker lesions identifies pNET patients benefiting from sunitinib treatment with implications for maintenance of dose intensity and future trial design

Targeting cancer cell metabolism in pancreatic adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second leading cause of cancer death by 2030. Current therapeutic options are limited, warranting an urgent need to explore innovative treatment strategies. Due to specific microenvironment constraints including an extensive desmoplastic stroma reaction, PDAC faces major metabolic challenges, principally hypoxia and nutrient deprivation. Their connection with oncogenic alterations such as KRAS mutations has brought metabolic reprogramming to the forefront of PDAC therapeutic research. The Warburg effect, glutamine addiction, and autophagy stand as the most important adaptive metabolic mechanisms of cancer cells themselves, however metabolic reprogramming is also an important feature of the tumor microenvironment, having a major impact on epigenetic reprogramming and tumor cell interactions with its complex stroma. We present a comprehensive overview of the main metabolic adaptations contributing to PDAC development and progression. A review of current and future therapies targeting this range of metabolic pathways is provided

Influence of thermal history on the structure and properties of silicate glasses

We studied a set of float glass samples prepared with different fictive temperature by previous annealing around the glass transition temperature. We compared the results to previous measurements on a series of amorphous silica samples, also prepared with different fictive temperature. We showed that the modifications on the structure at a local scale are very small, the changes of physical properties are moderate but the changes on density fluctuations at a nanometer scale are rather large: 12 and 20% in float glass and silica, for relative changes of fictive temperature equal to 13 and 25% respectively. Local order and mechanical properties of silica vary in the opposite way compared to float glass (anomalous behavior) but the density fluctuations in both glasses increase with temperature and fictive temperature