PFAS: forever chemicals — persistent, bioaccumulative and mobile: reviewing the status and the need for their phase out and remediation of contaminated sites

Background Per- and polyfluorinated alkyl substances (PFAS) have received increasing scientific and political attention in recent years. Several thousand commercially produced compounds are used in numerous products and technical processes. Due to their extreme persistence in the environment, humans and all other life forms are, therefore, increasingly exposed to these substances. In the following review, PFAS will be examined comprehensively. Results The best studied PFAS are carboxylic and sulfonic acids with chain lengths of C4 to C14, particularly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These substances are harmful to aquatic fauna, insects, and amphibians at concentrations of a few µg/L or less, accumulate in organisms, and biomagnify in food webs. Humans, as the final link in numerous food chains, are subjected to PFAS uptake primarily through food and drinking water. Several PFAS have multiple toxic effects, particularly affecting liver, kidney, thyroid, and the immune system. The latter effect is the basis for the establishment of a tolerable weekly dose of only 4.4 ng/kg body weight for the sum of the four representatives PFOA, PFOS, perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) by the European Food Safety Authority (EFSA) in 2020. Exposure estimates and human biomonitoring show that this value is frequently reached, and in many cases exceeded. PFAS are a major challenge for analysis, especially of products and waste: single-substance analyses capture only a fragment of the large, diverse family of PFAS. As a consequence, sum parameters have gained increasing importance. The high mobility of per and polyfluorinated carboxylic and sulfonic acids makes soil and groundwater pollution at contaminated sites a problem. In general, short-chain PFAS are more mobile than long-chain ones. Processes for soil and groundwater purification and drinking water treatment are often ineffective and expensive. Recycling of PFAS-containing products such as paper and food packaging leads to carryover of the contaminants. Incineration requires high temperatures to completely destroy PFAS. After PFOA, PFOS and a few other perfluorinated carboxylic and sulfonic acids were regulated internationally, many manufacturers and users switched to other PFAS: short-chain representatives, per- and polyfluorinated oxo carboxylic acids, telomeric alcohols and acids. Analytical studies show an increase in environmental concentrations of these chemicals. Ultra-short PFAS (chain length C1–C3) have not been well studied. Among others, trifluoroacetic acid (TFA) is present globally in rapidly increasing concentrations. Conclusions The substitution of individual PFAS recognized as hazardous by other possibly equally hazardous PFAS with virtually unknown chronic toxicity can, therefore, not be a solution. The only answer is a switch to fluorine-free alternatives for all applications in which PFAS are not essential

A procedure for segmenting surfaces by symbolic and iconic image fusion, inB.Jähne

Abstract. This paper deals with the derivation of a symbolic surface description exploiting the information of multiple images while using a minimum of domain knowledge. We present a new concept for segmenting surfaces by fusing multiple images both on the iconic and on the symbolic description level. In a rst step a local 3D-reconstruction and interpretation is derived based on the result of a polymorphic feature extraction. It serves as prior information for a second step which re nes the initial segmentation using the radiometric image content. Examples of the proposed procedure are presented for the application of 3D-building reconstruction from aerial images.

EXPERIMENTELLE UNTERSUCHUNG DES DISKON-FLÜGELKONZEPTS ZUR BEEINFLUSSUNG DER WIRBELSCHLEPPE

Das am DLR in Göttingen (AS-EV) entwickelte DISKON-Flügelkonzept zur Beeinflussung der Wirbelschleppe im Nachlauf eines Flügels wird erstmalig experimentell auf seine Wirksamkeit und Effektivität hin untersucht. Die Messungen wurden am Wasserschleppkanal des DLR Göttingen (WSG) durchgeführt. Durch Zacken an der Hinterkante werden Wirbel in der Scherschicht (DISKONtinuitätsfläche) induziert, die gegenläufig zum Randwirbel an der Flügelspitze sind. Veränderungen in der Wirbelstruktur werden über einen Vergleich der Ergebnisse von DISKON-Modell und einem Referenzmodell bestimmt. Die beiden Flügelmodelle haben das gleiche Profil und eine Halbspannweite von s = 0,5 Meter. Die Wirbelschleppe wird über einen Bereich von bis zu 30 Spannweiten hinter dem Flügel mit der Stereo Particle Image Velocimetry (Stereo-PIV) untersucht. Parallel dazu werden die aerodynamischen Kräfte mit einem Dreikomponenten- Dynamometer (Piezo-Waage) erfasst, über welche die aerodynamische Ähnlichkeit der beiden Flügelmodelle nachgewiesen wird. Aus den Strömungsfeldmessungen werden unter anderem die Wirbelposition, die tangentiale Geschwindigkeit und die Zirkulationsverteilung über dem Wirbelradius bestimmt. Der Vergleich dieser Parameter ergibt eine Beeinflussung der Wirbelschleppe durch das DISKON-Flügelkonzept, die sich in einer Positionsveränderung, einer Umverteilung der Wirbelstärke in den äußeren Bereich und in einer Abschwächung der Tangentialgeschwindigkeit innerhalb des Wirbelzentrums verdeutlicht

Photogrammetry and remote sensing: New German standards (DIN) setting quality requirements of products generated by digital cameras, PAN-sharpening and classification

10 years after the first introduction of a digital airborne mapping camera in the ISPRS conference 2000 in Amsterdam, several digital cameras are now available. They are well established in the market and have replaced the analogue camera. A general improvement in image quality accompanied the digital camera development. The signal-to-noise ratio and the dynamic range are significantly better than with the analogue cameras. In addition, digital cameras can be spectrally and radiometrically calibrated. The use of these cameras required a rethinking in many places though. New data products were introduced. In the recent years, some activities took place that should lead to a better understanding of the cameras and the data produced by these cameras. Several projects, like the projects of the German Society for Photogrammetry, Remote Sensing and Geoinformation (DGPF) or EuroSDR (European Spatial Data Research), were conducted to test and compare the performance of the different cameras. In this paper the current DIN (Deutsches Institut fuer Normung - German Institute for Standardization) standards will be presented. These include the standard for digital cameras, the standard for ortho rectification, the standard for classification, and the standard for pan-sharpening. In addition, standards for the derivation of elevation models, the use of Radar / SAR, and image quality are in preparation. The OGC has indicated its interest in participating that development. The OGC has already published specifications in the field of photogrammetry and remote sensing. One goal of joint future work could be to merge these formerly independent developments and the joint development of a suite of implementation specifications for photogrammetry and remote sensing

OTUB1 inhibits CNS autoimmunity by preventing IFN-γ-induced hyperactivation of astrocytes.

Astrocytes are critical regulators of neuroinflammation in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Growing evidence indicates that ubiquitination of signaling molecules is an important cell-intrinsic mechanism governing astrocyte function during MS and EAE Here, we identified an upregulation of the deubiquitinase OTU domain, ubiquitin aldehyde binding 1 (OTUB1) in astrocytes during MS and EAE Mice with astrocyte-specific OTUB1 ablation developed more severe EAE due to increased leukocyte accumulation, proinflammatory gene transcription, and demyelination in the spinal cord as compared to control mice. OTUB1-deficient astrocytes were hyperactivated in response to IFN-γ, a fingerprint cytokine of encephalitogenic T cells, and produced more proinflammatory cytokines and chemokines than control astrocytes. Mechanistically, OTUB1 inhibited IFN-γ-induced Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling by K48 deubiquitination and stabilization of the JAK2 inhibitor suppressor of cytokine signaling 1 (SOCS1). Thus, astrocyte-specific OTUB1 is a critical inhibitor of neuroinflammation in CNS autoimmunity