Conformational analysis of 1,3-difluorinated alkanes

Fluorine substitution can have a profound impact on molecular conformation. Here, we present a detailed conformational analysis of how the 1,3-difluoropropylene motif (-CHF-CH2-CHF-) determines the conformational profiles of 1,3-difluoropropane, anti- and syn-2,4-difluoropentane, and anti- and syn-3,5-difluoroheptane. It is shown that the 1,3-difluoropropylene motif strongly influences alkane chain conformation, with a significant dependence on the polarity of the medium. The conformational effect of 1,3-fluorination is magnified upon chain extension, which contrasts with vicinal difluorination. Experimental evidence was obtained from NMR analysis, where polynomial complexity scaling simulation algorithms were necessary to enable J-coupling extraction from the strong second-order spectra, particularly for the large 16-spin systems of the difluorinated heptanes. These results improve our understanding of the conformational control toolkit for aliphatic chains, yield simple rules for conformation population analysis, and demonstrate quantum mechanical time-domain NMR simulations for liquid state systems with large numbers of strongly coupled spins.</p

Transport properties of iodide in a sandy aquifer: Hydrogeological modelling and field tracer tests

International audienceThe release of radioactive iodine into geological media from nuclear waste disposal is an issue that has tobe considered since iodine is a biophilic element. 129I is, with 99Tc, one of the two long-lived radionuclidesthat have the highest mobility in radioactive waste disposal. Within this context, iodide retardation is stilla matter of debate. A low value of the retardation factor is generally accepted in soils without organicmatter, but the possibility for sorption cannot be completely ruled out. Since isotopic exchange with naturallyoccurring iodine is one of the main potential sorption mechanisms, site-specific retention parametersare needed. In the present paper, we study iodide transport in a sandy aquifer. A hydrogeologicalmodel was built to fit deuterium, bromide and iodide breakthrough data from in situ tracer test experiments.Within the precision range of the fitting, iodide is excluded from 2.5% of the effective porosity byanionic exclusion and presents a field retention factor (Kd) lower than 0.025 L/kg

Intramolecular OH center dot center dot center dot Fluorine Hydrogen Bonding in Saturated, Acyclic Fluorohydrins: The gamma-Fluoropropanol Motif

International audienceFluorination is commonly exercised in compound property optimization. However, the influence of fluorination on hydrogen-bond (HB) properties of adjacent functional groups, as well as the HB-accepting capacity of fluorine itself, is still not completely understood. Although the formation of OH center dot center dot center dot F intramolecular HBs (IMHBs) has been established for conformationally restricted fluorohydrins, such interaction in flexible compounds remained questionable. Herein is demonstrated for the first time-and in contrast to earlier reports-the occurrence of OH center dot center dot center dot F IMHBs in acyclic saturated g-fluorohydrins, even for the parent 3-fluoropropan-1-ol. The relative stereochemistry is shown to have a crucial influence on the corresponding (h1)J(OH center dot center dot center dot F) values, as illustrated by syn- and anti-4-fluoropentan-2-ol (6.6 and 1.9 Hz). The magnitude of OH center dot center dot center dot F IMHBs and their strong dependence on the overall molecular conformational profile, fluorination motif, and alkyl substitution level, is rationalized by quantum chemical calculations. For a given alkyl chain, the ``rule of shielding'' applies to OH center dot center dot center dot F IMHB energies. Surprisingly, the predicted OH center dot center dot center dot F IMHB energies are only moderately weaker than these of the corresponding OH center dot center dot center dot OMe. These results provide new insights of the impact of fluorination of aliphatic alcohols, with attractive perspectives for rational drug design

RF naprašované amorfní chalkogenidové tenké vrstvy pro povrchem zesílenou infračervenou absorpční spektroskopii

The primary objective of this study is the development of transparent thin film materials in the IR enabling strong infrared absorption of organic compounds in the vicinity of metal nanoparticles by the surface plasmon effect. For developing these optical micro-sensors, heterostructures combining gold nanoparticles and chalcogenide planar waveguides are fabricated and adequately characterized. Single As2S3 and Ge25Sb10Se65 amorphous chalcogenide thin films are prepared by radiofrequency magnetron sputtering. For the fabrication of gold nanoparticles on a chalcogenide planar waveguide, direct current sputtering is employed. Fabricated single layers or hetero-structures are characterized using various techniques to investigate the influence of deposition parameters. The nanoparticles of gold are functionalized by a self-assembled monolayer of 4-nitrothiophenol. Finally, the surface enhanced infrared absorption spectra of 4-nitrothiophenol self-assembled on fabricated Au/Ge-Sb-Se thin films hetero-structures are measured and analyzed. This optical component presents a ~24 enhancement factor for the detection of NO2 symmetric stretching vibration band of 4-nitrothiophenol at 1336 cm−1.Pro vývoj optických mikrosenzorů byly připraveny a adekvátně charakterizovány heterostruktury kombinující nanočástice zlata a chalkogenidové planární vlnovody. Amorfní chalkogenidové tenké vrstvy As2S3 a Ge25Sb10Se65 byly připraveny radiofrekvenčním magnetronovým naprašováním. Připravené vrstvy či heterostruktury jsou charakterizovány různými technikami s cílem studovat vliv depozičních podmínek. Nanočástice zlata jsou funkcionalizovány samouspořádanou monovrstvou 4-nitrothiofenolu. Byla změřena a analyzována povrchem zesílená infračervená absorpční spektra 4-nitrothiofenolu na připravených Au/Ge-Sb-Se tenkovrstvých heterostrukturách. Tato optická součást prokázala 24 násobné zesílení pro detekci symetrické valenční vibrace NO2 4-nitrothiofenolu při 1336 cm(-1)

RF sputtered amorphous chalcogenide thin films for surface enhanced infrared absorption spectroscopy

The primary objective of this study is the development of transparent thin film materials in the IR enabling strong infrared absorption of organic compounds in the vicinity of metal nanoparticles by the surface plasmon effect. For developing these optical micro-sensors, hetero-structures combining gold nanoparticles and chalcogenide planar waveguides are fabricated and adequately characterized. Single As2S3 and Ge25Sb10Se65 amorphous chalcogenide thin films are prepared by radio-frequency magnetron sputtering. For the fabrication of gold nanoparticles on a chalcogenide planar waveguide, direct current sputtering is employed. Fabricated single layers or hetero-structures are characterized using various techniques to investigate the influence of deposition parameters. The nanoparticles of gold are functionalized by a self-assembled monolayer of 4-nitrothiophenol. Finally, the surface enhanced infrared absorption spectra of 4-nitrothiophenol self-assembled on fabricated Au/Ge-Sb-Se thin films hetero-structures are measured and analyzed. This optical component presents a similar to 24 enhancement factor for the detection of NO2 symmetric stretching vibration band of 4-nitrothiophenol at 1336 cm(-1)

International survey among hepatologists and pulmonologists on the hepatic hydrothorax: plea for recommendations

Abstract Background The Hepatic hydrothorax is a pleural effusion related to portal hypertension; its diagnosis and therapeutic management may be difficult. The aims of this article are which follows: To gather the practices of hepatogastroenterologists or pulmonologists practitioners regarding the diagnosis and management of the hepatic hydrothorax. Methods Practitioners from 13 French- speaking countries were invited to answer an online questionnaire on the hepatic hydrothorax diagnosis and its management. Results Five hundred twenty-eight practitioners (80% from France) responded to this survey. 75% were hepatogastroenterologists, 20% pulmonologists and the remaining 5% belonged to other specialities. The Hepatic hydrothorax can be located on the left lung for 64% of the responders (66% hepatogastroenterologists vs 57% pulmonologists; p = 0.25); The Hepatic hydrothorax can exist in the absence of clinical ascites for 91% of the responders (93% hepatogastroenterologists vs 88% pulmonologists; p = 0.27). An Ultrasound pleural scanning was systematically performed before a puncture for 43% of the responders (36% hepatogastroenterologists vs 70% pulmonologists; p < 0.001). A chest X-ray was performed before a puncture for 73% of the respondeurs (79% hepatogastroenterologists vs 54% pulmonologists; p < 0.001). In case of a spontaneous bacterial empyema, an albumin infusion was used by 73% hepatogastroenterologists and 20% pulmonologists (p < 0.001). A drain was used by 37% of the responders (37% hepatogastroenterologists vs 31% pulmonologists; p = 0.26).An Indwelling pleural catheter was used by 50% pulmonologists and 22% hepatogastroenterologists (p < 0.01). TIPS was recommended by 78% of the responders (85% hepatogastroenterologists vs 52% pulmonologists; p < 0.001) and a liver transplantation, by 76% of the responders (86% hepatogastroenterologists vs 44% pulmonologists; p < 0.001). Conclusions The results of this large study provide important data on practices of French speaking hepatogastroenterologists and pulmonologists; it appears that recommendations are warranted

Early Hepatocellular Carcinoma Detection Using Magnetic Resonance Imaging Is Cost-Effective in High-Risk Patients with Cirrhosis

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Similar 5-year HCC occurrence in Tenofovir- and Entecavir-treated HBV chronic infection in the French AFEF/ANRS CO22 Hepather cohort.

International audienceBackground: Chronic hepatitis B virus (HBV) infection results in a high risk of cirrhosis and its complications, cirrhosis decompensation (DC), hepatocellular carcinoma (HCC), liver transplantation (LT), death or any of these outcomes (composite endpoint [CE]). Nucleos(t)ide analogues (NUCs) such as tenofovir or entecavir are associated with a reduction in these complications.Aim: To compare the impact of tenofovir and entecavir on these outcomes in patients treated for HBV infection and included in the prospective Hepather cohort.Methods: All patients with HBV infection who had received tenofovir or entecavir for more than 6 months at or after entry in the ANRS CO22 cohort were selected. Patients with HDV and HCV co-infection or prior liver event were excluded. Incidence rates of events were compared using inverse probability of treatment weighting (IPW).Results: The cohort included 1800 patients (986 tenofovir and 814 entecavir). Median follow-up was 4.2 years. The incidences of HCC, DC, LT, ACD, LRD and CE were not different between tenofovir- (1.8 (0.9; 3.2), 0.6 (0.2; 1.6), 0.2 (0.0; 0.8), 1.7 (0.8; 3.0), 0.8 (0.2, 1.8) and 4.1 (3.0; 5.4) per 1000 person-years) and entecavir-treated patients (1.6 (0.7; 3.0), 0.7 (0.2; 1.8), 0.2 (0.0; 1.0), 3.0 (1.7, 4.8), 0.5 (0.1; 1.5) and 5.0 (3.3; 7.2)) per 1000 person-years, respectively.Conclusion: The risk of liver-related events or death was not different between tenofovir- and entecavir-treated patients in this large prospective cohort of predominantly non-cirrhotic French patients.Trial registration number: NCT019553458

Development of the CMS detector for the CERN LHC Run 3

International audienceSince the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger