Spatially and Temporally Resolved Analysis of Bleeding in a Centrifugal Partition Chromatography Rotor

Centrifugal Partition Chromatography (CPC) is a separation technique that utilizes immiscible liquid phases to purify compounds. The selection of solvents in Liquid–Liquid Chromatography offers flexibility and optimization possibilities for specific separation tasks. Understanding the hydrodynamics inside the apparatus is crucial for optimizing a CPC process. The phase retention ratio (Sf) determines the apparatus’s operating point and separation efficiency. However, stationary phase leakage, known as bleeding, complicates the immobilization of this phase. We used a partly transparent single-disc rotor to investigate the time and space dependency of bleeding inside a CPC apparatus, enabling real-time and localized determination of the phase retention ratio. By tracking the retention values over time, we observed the bleeding phenomenon and its progression from the inlet to the rotor outlet. Depending on the phase system used, the CPC was utilizable for a separation task for only 173–500 dimensionless residence times. Systems with a higher stability parameter (as described in the literature) showed a lower bleeding rate and increased stability over time. Accordingly, our results demonstrate the importance of maintaining an optimal ratio of mobile to stationary phase for efficient separation

Navigating Algeria towards a sustainable green hydrogen future to empower North Africa and Europe’s clean hydrogen transition

Algeria, richly-endowed with renewable resources, is well-positioned to become a vital green hydrogen provider to Europe. Aiming to aid policymakers, stakeholders, and energy sector participants, this study embodies the first effort in literature to investigate the viability and cost-effectiveness of implementing green hydrogen production projects destined for exports to Europe via existing pipelines. A land suitability analysis utilizing multi-criteria decision making (MCDM) coupled with geographical information system (GIS) identified that over 43.55% of Algeria is highly-suitable for hydrogen production. Five optimal locations were investigated utilizing Hybrid Optimization of Multiple Electric Renewables (HOMER), with solar-hydrogen proving the most cost-effective option. Wind-based production, offering higher output volumes reaching 968 kg/h, requires turbine cost reductions of 17.50% (Ain Salah) to 54.50% (Djanet) to achieve a competitive levelized cost of hydrogen (LCOH) of $3.85/kg with PV systems. A techno-economic sensitivity analysis was conducted, identifying Djanet as the most promising location for a 100 MW solar-hydrogen plant, with a competitive LCOH ranging from$1.96/kg to $4.85/kg.</p

Kinetics of Anti–SARS-CoV-2 IgG Antibodies in Hemodialysis Patients Six Months after Infection

International audienceBackground: The humoral response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the hemodialysis population, including its dynamics over time, remains poorly understood.Methods: To analyze initial and long-term humoral responses against SARS-CoV-2 in a hemodialysis population, we retrospectively evaluated findings from SARS-CoV-2 IgG serologic assays targeting the nucleocapsid antigen or spike antigen up to 6 months of follow-up in patients on hemodialysis in the Paris, France, region who had recovered from coronavirus disease 2019 (COVID-19).Results: Our analysis included 83 patients (median age 65 years); 59 (71%) were male and 28 (34%) had presented with severe COVID-19. We observed positive initial SARS-CoV-2 IgG antinucleocapsid serology in 74 patients (89%) at a median of 67 days postdiagnosis. By multivariable analysis, immunocompromised status was the only factor significantly associated with lack of an IgG antinucleocapsid antibody response. Follow-up data were available at 6 months postdiagnosis for 60 of 74 patients (81%) with positive initial antinucleocapsid serology, and 15 (25%) of them had negative antinucleocapsid serology at month 6. In total, 14 of 15 sera were tested for antispike antibodies, 3 of 14 (21%) of which were also negative. Overall, 97% of antinucleocapsid-antibody-positive specimens were also antispike-antibody positive. Female sex, age >70 years, and nonsevere clinical presentation were independently associated with faster IgG antinucleocapsid titer decay in multivariable analysis. After adjustment for sex and age >70 years, nonsevere clinical presentation was the only factor associated with faster decay of IgG antispike antibodies.Conclusions: This study characterizes evolution of the SARS-CoV-2 antibody response in patients on hemodialysis and identifies factors that are associated with lack of seroconversion and with IgG titer decay

Heterodyne coherent detection of phase modulation in a mid-infrared unipolar device

International audiencePhase modulation is demonstrated in a quantum Stark effect modulator designed to operate in the mid-infrared at wavelength around 10 µm. Both phase and amplitude modulation are simultaneously resolved through the measurement of the heterodyne signal arising from the beating of a quantum cascade laser with a highly stabilized frequency comb. The highest measured phase shift is more than 5 degrees with an associated intensity modulation of 5 %. The experimental results are in full agreement with our model in which the complex susceptibility is precisely described considering the linear voltage dependent Stark shift of the optical resonance