University of Rennes

About: University of Rennes is a education organization based out in Rennes, France. It is known for research contribution in the topics: Population & Crystal structure. The organization has 18404 authors who have published 40374 publications receiving 995327 citations.

JCPDS--International Centre for Diffraction Data round robin study of silver behenate. A possible low-angle X-ray diffraction calibration standard

Abstract: A task group of the JCPDS—International Center for Diffraction Data (ICDD) was established with the charge of investigating the use of silver behenate, CH 3 (CH 2 ) 20 COO·Ag, as a possible low-angle calibration standard for powder diffraction applications. Utilizing several data collection and analysis techniques, long-period spacing ( d 001 ) values with a range of 58.219–58.480 A were obtained. Using the same collected data and one data analysis refinement calculation method resulted in dm values with a range of 58.303–58.425 A. Data collected using a silicon internal standard and the same singular data analysis calculation method provided d 001 values with a range of 58.363–58.381 A.

Beyond Stereoselectivity, Switchable Catalysis: Some of the Last Frontier Challenges in Ring‐Opening Polymerization of Cyclic Esters

Abstract: Metal-based catalysts and initiators have played a pivotal role in the ring-opening polymerization (ROP) of cyclic esters, thanks to their high activity and remarkable ability to control precisely the architectures of the resulting polyesters in terms of molar mass, dispersity, microstructure, or tacticity. Today, after two decades of extensive research, the field is slowly reaching maturity. However, several challenges remain, while original concepts have emerged around new types or new applications of catalysis. This Review is not intended to comprehensively cover all of these aspects. Rather, it provides a personal overview of the very recent progress achieved in some selected, important aspects of ROP catalysis-stereocontrol and switchable catalysis. Hence, the first part addresses the development of new metal-based catalysts for the isoselective ROP of racemic lactide towards stereoblock copolymers, and the use of syndioselective ROP metal catalysts to control the monomer sequence in copolymers. A second part covers the development of ROP catalysts-primarily metal-based catalysts, but also organocatalysts-that can be externally regulated by the use of chemical or photo stimuli to switch them between two states with different catalytic abilities. Current challenges and opportunities are highlighted.

Comparison of predictive accuracy of four prognostic models for nonmetastatic renal cell carcinoma after nephrectomy: a multicenter European study

Abstract: BACKGROUND The objective of the current study was to compare, in a large multicenter study, the discriminating accuracy of four prognostic models developed to predict the survival of patients undergoing nephrectomy for nonmetastatic renal cell carcinoma (RCC). METHODS A total of 2404 records of patients from 6 European centers were retrospectively reviewed. For each patient, prognostic scores were calculated according to four models: the Kattan model, the University of California at Los Angeles integrated staging system (UISS) model, the Yaycioglu model, and the Cindolo model. Survival curves were estimated by the Kaplan–Meier method and compared by the log-rank test. Discriminating ability was assessed by the Harrell c-index for censored data. The primary end point was overall survival (OS), and the secondary end points were cancer-specific survival (CSS) and disease recurrence-free survival (RFS). RESULTS At last follow-up, 541 subjects had died of any causes, with a 5-year OS rate of 80%. The 5-year CSS and RFS rates were 85% and 78%, respectively. All models discriminated well (P < 0.0001). The c-indexes for OS were 0.706 for the Kattan nomogram, 0.683 for the UISS model, and 0.589 and 0.615 for the Yaycioglu and Cindolo models, respectively. The Kattan nomogram was found to improve discrimination substantially in the UISS intermediate-risk patients. CONCLUSIONS The current study appears to better define the general applicability of prognostic models for predicting survival in patients with nonmetastatic RCC treated with nephrectomy. The results suggest that postoperative models discriminate substantially better than preoperative ones. The Kattan model was consistently found to be the most accurate, although the UISS model was only slightly less well performing. The Kattan model can be useful in the UISS intermediate-risk patients. Cancer 2005. © 2005 American Cancer Society.