AC2T Research (Austria)

Organic acids are, besides inorganic constituents, important components of cloud water samples. Typical analytes include monocarboxylic, dicarboxylic, tricarboxylic, and aromatic carboxylic acids. They are either scavenged from the gas and aerosol phase or formed within cloud droplets via chemical reactions in the aqueous phase. Concentrations in cloud water depend on meteorological conditions, air mass origin, and cloud properties, including cloud type and liquid water content. Organic acids influence cloud chemistry, facilitate cloud droplet formation, and increasingly contribute to the acidity of cloud water.We present the results of two cloud water sampling campaigns conducted in August 2024 and May 2025 at Sonnblick Observatory (3106 m a.s.l.) in the Austrian Alps. The sampling campaigns were conducted within the framework of ACTRIS activities. Depending on the season, sampling comprised warm clouds as well as mixed-phase clouds, including periods coinciding with mineral dust events. Chemical analyses of organic acids were performed using ion chromatography with conductivity and mass spectrometry detection. Further analyses included inorganic ions, pH, conductivity, and selected carbohydrates.One part of the evaluations focuses on methodological topics, such as the comparison of different analytical set-ups used for the analysis of organic acids. The advantage of mass spectrometry detection is demonstrated by the analysis of several coeluting substances that cannot be resolved by routine gradient ion chromatography. Additionally, the ion concentrations of organic acids observed during the two sampling campaigns are shown and discussed with respect to the overall chemical composition and meteorological conditions. Finally, the contribution of organic acids to the overall acidity of cloud water is discussed and evaluated in comparison with earlier measurements from the 1990s conducted at Sonnblick Observatory.

Rapid and accurate bacteria identification, particularly Escherichia coli (E. coli), is essential in the monitoring of health, environment, and food safety. E. coli, a prevalent pathogenic bacterium, serves as a key indicator of food and water contamination. Carbon quantum dots (CQDs) have appeared as promising fluorescent probes because of their small size, ease of synthesis, low toxicity, and tunable fluorescence using different carbon-rich precursors. Advances in both bottom-up and top-down synthesis procedures have enabled precise control over CQD properties and surface functionalities, enhancing their capabilities in biosensing. Among the critical factors influencing CQD performance is the strategic selection of precursors, which determines the surface chemistry and recognition potential of the resulting nanodots. The integration with other nanomaterials and the surface modification of CQDs with specific functional groups or recognition elements further improves their sensitivity and selectivity toward E. coli. This review summarizes recent progress in the modification of CQDs for the fluorescent detection of E. coli, highlighting relevant sensing mechanisms and the influence of different precursors, such as antibiotics and sugars, as well as various functionalization and surface modification strategies. The aim is to provide insight into the rational design of efficient, selective, and cost-effective CQD-based biosensors for bacterial detection.

• Hydrocolloidal biofilm imitations achieve viscoelastic behaviour like the biofilm. • Alginate based imitations achieve greatest similarity in tribological measurements. • Testing in the native biofilm environment is key for consistent tribological results. Biofilm removal remains a challenge in the food industry. Strategies often rely on mechanical methods, highlighting the need to understand mechanical properties. However, cultivating consistent biofilms is difficult. Hence, the characterisation and tailoring of imitations is required. Developing imitations for the optimisation of cleaning procedures and the validation of cleaning protocols requires similar mechanical and physicochemical properties. This study aimed to characterise the rheological and tribological behaviour of Microbacterium lacticum biofilms on 2B cold-rolled stainless-steel plates and selected imitations based on gellan or alginate. Given the rarity of tribological measurements for biofilms, testing conditions were evaluated. Microscopic evaluations provided insights into biofilm morphology. Biofilm properties were shown to depend on growth conditions and environmental influences, while imitation properties can be controlled by formulation approaches. In rheological measurements the imitations showed viscoelastic behaviour, typical for biofilms, suggesting a similar cleaning behaviour. Tribological tests revealed that alginate-based samples closely resembled native biofilms, with coefficient of friction values ranging between 0.24 to 0.36. For consistent results of the tribological evaluation, using a test setup within the native biofilm environment is suggested. For this set up aluminium oxide as an inert counterbody resulted in steady state friction values particularly for loads of 500 mN. Overall, by finding a suitable biofilm imitation, this study enhances the understanding of biofilm mechanics and possible test methods, paving the way for improved cleaning strategies. Further refinement of the imitations is suggested and practical cleaning trials are needed to validate the imitations for cleaning tests.

Abstract Diamond-like carbon (DLC) coatings are widely employed to extend the service life of components exposed to severe tribological conditions, particularly where uncoated surfaces would fail under boundary and mixed lubrication. For reliable application, a mechanistic understanding of mild wear processes in such regimes is essential. In this study, in-situ wear rate measurements were performed using a reciprocating tribometer to evaluate DLC-coated specimens against steel counter bodies under low-viscosity lubricants with distinct chemical compositions, namely water and diesel fuels (fresh and aged). A series of hydrogenated and hydrogen-free DLC coatings with varying sp3/sp2 hybridisation ratios and hardness were investigated. The results indicate that under mild wear conditions, lubricant properties — most notably dynamic viscosity (~ 1–3 mPa·s) and oxidation state — dominate the wear response, while the DLC coating’s sp3/sp2 ratio and mechanical properties exert a secondary influence. Hydrogenated, sp2-rich DLCs exhibited superior wear resistance due to their enhanced ability to form passivating hydroxyl layers, which suppress graphitisation-induced degradation. In contrast, water-based lubrication, while promoting hydroxylation, led to increased wear due to steel counter body corrosion and third-body abrasion. Aged diesel lubricants resulted in lower DLC wear rates, attributable to increased oxidation promoting surface passivation. These findings highlight the necessity of jointly considering lubricant chemistry and DLC structural characteristics when designing tribological systems for low-wear applications.

Abstract In recent decades, energy harvesting in rotating tires has been an active field of research as this could avoid the use of toxic batteries, which are currently used to power pressure monitoring systems installed in millions of cars worldwide. However, due to the harsh mechanical conditions in a tire and the economic competition with low-cost and widely spread batteries, self-powered tire pressure monitoring systems have not yet entered the market. In this work we present a fully integrated and self-powered bicycle tube pressure monitoring system using a multilayer piezoelectric energy harvester based on P(VDF-TrFE) fabricated using low-cost and scalable screen-printing. The harvester design was optimised to increase the power output. In addition, the long-term durability of the system up to 5000 km was investigated. The durability tests show that for a real-world application, a compromise must be found between energy output and durability since both factors depend in opposite ways on the mechanical stress in the system.

Thermo-oxidation of biomass is an important process that occurs through a variety of reaction pathways depending on the chemical nature of the molecules and reaction conditions. These processes can be modeled using reactive molecular dynamics to study chemical reactions and the evolution of converted molecules over time. The advantage of this approach is that many molecules can be modeled, but it is challenging to use the large amount of data obtained from such a simulation to determine reaction products and pathways. In this study, we developed a tracking approach to identify the reaction pathways of the dominant reaction products from reactive molecular dynamics simulations. We demonstrated the approach for thermo-oxidation reactions of modified model lignin compounds. For two modified lignin structures, we tracked the evolving chemical species to find the most common reaction products. Subsequently, we monitored specific bonds to determine the individual steps in the reaction process. This combined approach of reactive molecular dynamics and tracking enabled us to identify the most likely thermo-oxidation pathways. The methodology can be used to investigate the thermo-oxidative pathways of a wider range of chemical compounds.

This study investigated two major trends shaping contemporary technological progress: the growing complexity of innovation and the increasing reliance on government support for private research and development (R&D). We analyzed United States patent data from 1981 to 2016 using structural vector autoregressions and uncovered an indirect interplay between these trends. Our findings showed that government incentives and support played a crucial role in spurring private-sector innovation. This government-fueled innovation, in turn, paved the way for advancements in more intricate and sophisticated technological areas.Our study sheds light on the dual role of the United States' innovation policy over the past four decades; the policy has not only accelerated technological advancement but also steered it toward increasingly complex domains. While this trend presents opportunities for economic growth and technological breakthroughs, it also poses challenges, including the potential for further escalating R&D costs. This research has significant implications for policymakers and industry leaders, suggesting a need for a balanced approach to fostering innovation while considering the long-term economic and technological landscape.