Combined macro X-ray fluorescence (MA-XRF) and pulse phase thermography (PPT) imaging for the technical study of panel paintings.

Museum staff usually relies on a proven combination of X-ray radiography (XRR) and infrared reflectography (IRR) to study paintings in a non-destructive manner. In the last decades, however, the research toolbox of heritage scientists has expanded considerably, with a prime example being macro X-ray fluorescence (MA-XRF), producing element-specific images. The goal of this article is to illustrate the added value of augmenting MA-XRF with pulse phase thermography (PPT), a variant of active infrared thermographic imaging (IRT), which is an innovative diagnostic method that is able to reveal variations between or in materials, based on a different response to minor fluctuations in temperature when irradiated with optical radiation. By examining three 16th- and 17th-century panel paintings we assess the extent in which combined MA-XRF and PPT contributes to a better understanding of two commonly encountered interventions to panel paintings: (a) Anstückungen (enlargement of the panel) or (b) substitutions (replacement of part of the panel). Yielding information from different depths of the painting, these two techniques proved highly complementary with IRR and XRR, expanding the understanding of the build-up, genesis, and material history of the paintings. While MA-XRF documented the interventions to the wooden substrate indirectly by revealing variations in painting materials, paint handling and/or layer sequence between the original part and the extended or replaced planks, PPT proved beneficial for the study of the wooden support itself, by providing a clear image of the wood structure quasi-free of distortion by the superimposed paint or cradling. XRR, on the other hand, revealed other features from the wood structure, not visible with PPT, and allowed looking through the wooden panels, revealing e.g. the dowels used for joining the planks. Additionally, IRR visualised dissimilarities in the underdrawings. In this way, the results indicate that PPT has the potential to become an acknowledged add-on to the expanding set of imaging methods for paintings, especially when used in combination with MA-XRF, IRR and XRR.

Inactivation of SARS-CoV-2 and Other Enveloped and Non-Enveloped Viruses with Non-Thermal Plasma for Hospital Disinfection.

As recently highlighted by the SARS-CoV-2 pandemic, viruses have become an increasing burden for health, global economy, and environment. The control of transmission by contact with contaminated materials represents a major challenge, particularly in hospital environments. However, the current disinfection methods in hospital settings suffer from numerous drawbacks. As a result, several medical supplies that cannot be properly disinfected are not reused, leading to severe shortages and increasing amounts of waste, thus prompting the search for alternative solutions. In this work, we report that non-thermal plasma (NTP) can effectively inactivate SARS-CoV-2 from non-porous and porous materials commonly found in healthcare facilities. We demonstrated that 5 min treatment with a dielectric barrier discharge NTP can inactivate 100% of SARS-CoV-2 (Wuhan and Omicron strains) from plastic material. Using porcine respiratory coronavirus (surrogate for SARS-CoV-2) and coxsackievirus B3 (highly resistant non-enveloped virus), we tested the NTP virucidal activity on hospital materials and obtained complete inactivation after 5 and 10 min, respectively. We hypothesize that the produced reactive species and local acidification contribute to the overall virucidal effect of NTP. Our results demonstrate the potential of dielectric barrier discharge NTPs for the rapid, efficient, and low-cost disinfection of healthcare materials.

A Continuous Motion Shape-from-Focus Method for Geometry Measurement during 3D Printing.

In 3D printing, as in other manufacturing processes, there is a push for zero-defect manufacturing, mainly to avoid waste. To evaluate the quality of the printed parts during the printing process, an accurate 3D measurement method is required. By scanning the part during the buildup, potential nonconformities to tolerances can be detected early on and the printing process could be adjusted to avoid scrapping the part. Out of many, shape-from-focus, is an accurate method for recovering 3D shapes from objects. However, the state-of-the-art implementation of the method requires the object to be stationary during a measurement. This does not reconcile with the nature of 3D printing, where continuous motion is required for the manufacturing process. This research presents a novel methodology that allows shape-from-focus to be used in a continuous scanning motion, thus making it possible to apply it to the 3D manufacturing process. By controlling the camera trigger and a tunable lens with synchronous signals, a stack of images can be created while the camera or the object is in motion. These images can be re-aligned and then used to create a 3D depth image. The impact on the quality of the 3D measurement was tested by analytically comparing the quality of a scan using the traditional stationary method and of the proposed method to a known reference. The results demonstrate a 1.22% degradation in the measurement error.

Catalytic Promiscuity of cGAS: A Facile Enzymatic Synthesis of 2'-3'-Linked Cyclic Dinucleotides.

Cyclic GMP-AMP synthase (cGAS) is a cytosolic DNA sensor that catalyzes the synthesis of the cyclic GMP-AMP dinucleotide 2'3'-cGAMP. 2'3'-cGAMP functions as inducer for the production of type I interferons. Derivatives of this important second messenger are highly valuable for pharmaceutical applications. However, the production of these analogues requires complex, multistep syntheses. Herein, human cGAS is shown to react with a series of unnatural nucleotides, thus leading to novel cyclic dinucleotides. Most substrate derivatives with modifications at the nucleobase, ribose, and the α-thio phosphate were accepted. These results demonstrate the catalytic promiscuity of human cGAS and its utility for the biocatalytic synthesis of cyclic dinucleotide derivatives.

Maximizing the stability of metabolic engineering-derived whole-cell biocatalysts.

A systematic and powerful knowledge-based framework exists for improving the activity and stability of chemical catalysts and for empowering the commercialization of respective processes. In contrast, corresponding biotechnological processes are still scarce and characterized by case-by-case development strategies. A systematic understanding of parameters affecting biocatalyst efficiency, that is, biocatalyst activity and stability, is essential for a rational generation of improved biocatalysts. Today, systematic approaches only exist for increasing the activity of whole-cell biocatalysts. They are still largely missing for whole-cell biocatalyst stability. In this review, we structure factors affecting biocatalyst stability and summarize existing, yet not completely exploited strategies to overcome respective limitations. The factors and mechanisms related to biocatalyst destabilization are discussed and demonstrated inter alia based on two case studies. The factors are similar for processes with different objectives regarding target molecule or metabolic pathway complexity and process scale, but are in turn highly interdependent. This review provides a systematic for the stabilization of whole-cell biocatalysts. In combination with our knowledge on strategies to improve biocatalyst activity, this paves the way for the rational design of superior recombinant whole-cell biocatalysts, which can then be employed in economically and ecologically competitive and sustainable bioprocesses.