17 research outputs found
Reactive Desorption of CO Hydrogenation Products under Cold Pre-stellar Core Conditions
The astronomical gas-phase detection of simple species and small organic
molecules in cold pre-stellar cores, with abundances as high as
n, contradicts the generally accepted idea
that at K, such species should be fully frozen out on grain surfaces. A
physical or chemical mechanism that results in a net transfer from solid-state
species into the gas phase offers a possible explanation. Reactive desorption,
i.e., desorption following the exothermic formation of a species, is one of the
options that has been proposed. In astronomical models, the fraction of
molecules desorbed through this process is handled as a free parameter, as
experimental studies quantifying the impact of exothermicity on desorption
efficiencies are largely lacking. In this work, we present a detailed
laboratory study with the goal of deriving an upper limit for the reactive
desorption efficiency of species involved in the CO-HCO-CHOH
solid-state hydrogenation reaction chain. The limit for the overall reactive
desorption fraction is derived by precisely investigating the solid-state
elemental carbon budget, using reflection absorption infrared spectroscopy and
the calibrated solid-state band-strength values for CO, HCO and CHOH.
We find that for temperatures in the range of to K, an upper limit of
for the overall elemental carbon loss upon CO conversion into
CHOH. This corresponds with an effective reaction desorption fraction of
per hydrogenation step, or per H-atom induced
reaction, assuming that H-atom addition and abstraction reactions equally
contribute to the overall reactive desorption fraction along the hydrogenation
sequence. The astronomical relevance of this finding is discussed.Comment: 9 pages, 7 figure
The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study
AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4âweeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4âweeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, PÂ =Â 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, Pâ<â0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, PÂ =Â 0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, PÂ =Â 0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease
A computed tomography study of the fibula: morphology, morphometry, intramedullary anatomy, application prospects on intramedullary nailing
International audienc
Flexibility of molecular films as determined by deuterium solid state NMR
A new technique is proposed for the measurement of the bilayer bending modulus , in the lamellar phase L of lyotropic systems. It resides in the measurement of quadrupolar splittings by deuterium solid state NMR. By separating the different motional contributions accounting for the reorientation of the C-D bond with respect to the magnetic field, we have calculated within a simple Gaussian theory the effect of thermal fluctuations of the film upon the recorded quadrupolar splitting. This has been applied to the study of the effects of membrane composition on the mean bending modulus in ternary and pseudo ternary systems of water-(salt)-sodium dodecyl sulfate-alcohol. It is found that is sensitive both to the amount of alcohol in the membrane and to the alcohol chain length, with typical values increasing between 1.3 and 13.0 from bexanol to decanol systems. Our results allow to attribute the reduction in obtained by replacing surfactant by alcohol to the thinning of the membrane and to the increase of the area occupied by the surfactant at the interface
Histochemical localization of alkaline pyrophosphate- phosphohydrolase in tooth-forming cells of rat
Formation of Complex Organic Molecules in Cold Interstellar Environments through Nondiffusive Grain-surface and Ice-mantle Chemistry
ONCOGRAM: study protocol for the evaluation of therapeutic response and survival of metastatic colorectal cancer patients treated according to the guidelines of a chemosensitivity assay, the OncogrammeÂź
International audienceAbstract Background Colorectal cancer is a major public concern, being the second deadliest cancer in the world. Whereas survival is high for localized forms, metastatic colorectal cancer has showed poor prognosis, with a 5-year survival barely surpassing 11%. Conventional chemotherapies against this disease proved their efficiency and remain essential in first-line treatment. However, the large number of authorized protocols complexifies treatment decision. In common practice, such decision is made on an empirical basis, by assessing benefits and risks for the patient. In other words, there is currently no efficient means of predicting the efficacy of any chemotherapy protocol for metastatic colorectal cancer. Methods/design The use of a chemosensitivity assay, the OncogrammeÂź, should help clinicians administer the best chemotherapy regimen to their patients. We hypothesize it would ultimately improve their survival. In this multicentred, prospective trial (ONCOGRAM), eligible patients with metastatic colorectal cancer are randomized to determine whether they will receive an OncogrammeÂź. For clinicians whose patients benefited from the assay (arm A), results are used as a decision support tool. Patients not undergoing the OncogrammeÂź procedure are treated according to current practice, without the assistance of the assay (arm B). Primary outcome is 1-year progression-free survival. Secondary outcomes include response rates, as well as 6-month and 1-year survival rates. Discussion This study aims at investigating the clinical utility of the OncogrammeÂź as a decision support tool for the treatment of patients with metastatic colorectal cancer. If the OncogrammeÂź positively influenced patient overall survival and/or progression-free survival, it would be of great value for clinicians to implement this assay within the current landscape of personalized medicine tools, which include genomics and biomarker assays. Trial registration ClinicalTrials.gov identifier NCT03133273 . Registered on April 28, 2017