Determination of mass attenuation coefficient by numerical absorption calibration with Monte-Carlo simulations at 59.54 keV

International audienceThis study presents a numerical method in order to determine the mass attenuation coefficient of a sample with an unknown chemical composition at low energy. It is compared with two experimental methods : a graphic method and a transmission method. The method proposes to realise a numerical absorption calibration curve to process experimental results. Demineralised water with known mass attenuation coefficient (0.2066 cm 2 .g −1 at 59.54 keV) is chosen to confirm the method. 0.1964 ± 0.0350 cm 2 .g −1 is the average value determined by the numerical method, that is to say less than 5% relative deviation compared to more than 47% for the experimental methods

Beam characterization of a lab bench cold cathode ultra-soft X-ray generator

International audienceThe aim of this work is to characterize the Ultra Soft X-ray (USX, 1.5 keV, Al Kα) photon beam of a customized lab bench cold cathode generator. Within this generator, the electron beam is slowed down in a thin aluminium foil (16 μm) supported by an easily exchangeable anode. It is shown that the thickness of the foil and the anode configuration determine the spatial distribution and the fluence rate of the photon beam, whereas accelerating voltage determines both fluence rate and energy spectrum feature. It is shown also that under specific operation parameters (i.e. accelerating voltage), a Gaussian energy distribution of the beam can be generated which is centred on the energy of the Al Kα line (1.5 keV). Dosimetric films of GAFCHROMIC® HD-810 were used to estimate the photon fluence rate distribution of the beam. Its variation, when the generator acts as a monoenergetic source, was characterized with the two different configurations of the anode assembly. Finally, it is verified that the anode assembly consisting in a flat washer, on which the aluminium foil is set, acts as a simple point-source

Dissociative electron attachment to DNA-diamine thin films: Impact of the DNA close environment on the OH(-) and O(-) decay channels.

International audience: We measure the desorption of anions stimulated by the impact of 0-20 eV electrons on highly uniform thin films of plasmid DNA-diaminopropane. The results are accurately correlated with film thickness and composition by AFM and XPS measurements, respectively. Resonant structures in the H(-), O(-), and OH(-) yield functions are attributed to the decay of transient anions into the dissociative electron attachment (DEA) channel. The diamine induces ammonium-phosphate bridges along the DNA backbone, which suppresses the DEA O(-) channel and in counter-part increases considerably the desorption of OH(-). The close environment of the phosphate groups may therefore play an important role in modulating the rate and type of DNA damages induced by low energy electrons

Well GeHP detector calibration for environmental measurements using reference materials

International audienceA well-type detector installed in the Modane underground Laboratory (LSM) can combine both low background and high detection efficiency and it is well suited for the analysis of small amounts of environmental samples. Reference materials such as IAEA-447 (moss-soil), IAEA-RG-Th1 and IAEA-RG-U1 were used for the detector calibration, owing to a chemical composition close to those of the environmental samples. Nevertheless , the matrix effects and the true coincidence summing effects must be corrected from the full energy peak efficiency (FEPE). The FEPE was performed for a wide range of energy by a semi-empirical method using Monte Carlo simulation (MCNP6), intended for environmental measurements such as lake sediments dating. In the well geometry, the true coincidence summing effects could be very important and correction factors have been computed in three different ways

Same data, different conclusions: Radical dispersion in empirical results when independent analysts operationalize and test the same hypothesis

In this crowdsourced initiative, independent analysts used the same dataset to test two hypotheses regarding the effects of scientists’ gender and professional status on verbosity during group meetings. Not only the analytic approach but also the operationalizations of key variables were left unconstrained and up to individual analysts. For instance, analysts could choose to operationalize status as job title, institutional ranking, citation counts, or some combination. To maximize transparency regarding the process by which analytic choices are made, the analysts used a platform we developed called DataExplained to justify both preferred and rejected analytic paths in real time. Analyses lacking sufficient detail, reproducible code, or with statistical errors were excluded, resulting in 29 analyses in the final sample. Researchers reported radically different analyses and dispersed empirical outcomes, in a number of cases obtaining significant effects in opposite directions for the same research question. A Boba multiverse analysis demonstrates that decisions about how to operationalize variables explain variability in outcomes above and beyond statistical choices (e.g., covariates). Subjective researcher decisions play a critical role in driving the reported empirical results, underscoring the need for open data, systematic robustness checks, and transparency regarding both analytic paths taken and not taken. Implications for organizations and leaders, whose decision making relies in part on scientific findings, consulting reports, and internal analyses by data scientists, are discussed

The Impact of the EU Taxonomy on Greenwashing : With a Case on the Swedish Sustainable Finance Sector

Background: The trend in environmental reporting has been continuously increasing. However, there is a lack of accepted uniform standards for accreditation, standardization, and evaluation of green investments, which slows down the process of mobilizing capital to meet sustainability objectives. In response to this, the European Union has created, in summer 2019, a new Taxonomy Regulation in an effort to increase green investing.  Purpose: Skepticism towards green organizations is on the rise and the phenomenon, namely greenwashing, can be argued to be one of the biggest threats to sustainable development. Previous research on greenwashing has so far only looked at the effects it has on consumers. This study identifies this research gap and alternatively investigates the perspective of the investors on greenwashing. Prior to the EU Taxonomy, there were limited regulations in place to ensure a universal measurement of sustainable actions that were mandatory. This raises the question of whether the EU Taxonomy truly has the potential to reduce greenwashing or not. A descriptive investigation of the current literature on problems of greenwashing within the financial sector can seek to identify the critical themes concerning the EU Taxonomy. Construct a framework on which the EU Taxonomy may be most effective in reducing the types of greenwashing.  Research Question: What is the potential of the new EU Taxonomy to increase transparency within the sustainable financial sector that is threatened by greenwashing? Method: Qualitative study; exploratory case study approach; the paradigm of interpretivism as our research philosophy; interviews based on the inductive approach, semi-structured interviews with a mix of open- and close-ended questions; purposive sampling method; triangulation data analysis with findings visualized in a tree diagram. Conclusion: A framework is presented that identifies the high/moderate/low potentials of the EU Taxonomy decreasing greenwashing in the financial sector. Our findings conclude that the EU Taxonomy showed great potential in giving a more comprehensive understanding of the company’s sustainable actions. The development of our findings contributes to a better current understanding of the threats of greenwashing for investors and can help to increase their confidence in sustainable investing

Reductive unfolding of serum albumine uncovered by Raman spectroscopy

International audienceThe reductive unfolding of bovine serum albumin (BSA) and human serum albumin (HSA) induced by dithiothreitol (DTT) is investigated using Raman spectroscopy. The resolution of the S-S Raman band into both protein and oxidized DTT contributions provides a reliable basis for directly monitoring the S-S bridge exchange reaction. The related changes in the protein secondary structure are identified by analyzing the protein amide I Raman band. For the reduction of one S-S bridge of BSA a mean Gibbs free energy of -7 kJ mol-1 is derived by studying the reaction equilibrium. The corresponding value for the HSA S-S bridge reduction is -2 kJ mol-1. The reaction kinetics observed via the S-S or amide I Raman bands are identical giving a reaction rate constant of (1.02 0.11) M-1 s-1 for BSA. The contribution of the conformational Gibbs free energy to the overall Gibbs free energy of reaction is further estimated by combining experimental data with ab initio calculations