FORTH Institute of Chemical Engineering Sciences

NASA and ESA launched the PACE and Earthcare satellites in 2024 to provide unique aerosol and cloud measurements. We use these measurements to constrain model uncertainty on aerosol Effective Radiative Forcing (ERF). Perturbed Parameter Ensembles (PPEs) are extremely powerful tools that offer an effective approach to evaluate and constrain the model uncertainty of aerosol using observations.We create a PPE for July 2024-August 2025 based on 250 simulations by the aerosol -climate model ECHAM-HAM and co-locate the 3-hourly output with aerosol and cloud products from PACE and Earthcare. We define regional monthly mean observations for 19 regions of fine- and coarse Aerosol Optical Depth (AOD), Aerosol Index (AI), Single Scattering Albedo (SSA), cloud droplet number concentration (Nd), Cloud Effective Radius (CER), and fraction of extinction below 2km altitude, resulting in almost 1600 observations. An emulator is used to extend the PPE to simulate these observations to 2 million PPE members and constrain the PPE by applying least-squares minimization. resulting in 0.2% of accepted ensemble members.Both PACE and EarthCARE independently and consistently constrain several model parameters that affect ERFaci and RFari. These observations fundamentally and consistently change where and how ERF uncertainty is controlled and alter the global spatial ERF distribution. The constrained ensemble indicates a stronger negative global aerosol ERF than previous mean estimates, alongside a more positive forcing over Central Africa. The observations suggest a reduction of emission of DMS, Organic, and Black Carbon (anthropogenic and biomass burning), and accumulation mode sea salt. Also, the absorption capability (imaginary refractive index) of different aerosol species is reduced. Cloud observations constrain ‘activation’ and ‘vertical velocity’ parameters, resulting in smaller aerosol-Nd susceptibility. However, some parameter uncertainties, such as biomass burning emission particle size, remain mostly unchanged. These results demonstrate that new satellite observations can robustly and consistently constrain aerosol ERF uncertainty, while also identifying key processes where additional or complementary observations are required.

Motor vehicles remain a significant contributor to urban air pollution, emitting compounds in both the gas and particulate phases. While emissions under hot driving conditions have decreased due to improvements in exhaust after-treatment systems, cold starts continue to contribute disproportionately to total vehicle emissions. Furthermore, gas-phase organic compounds emitted during cold starts can be oxidized in the atmosphere, leading to the formation of secondary organic aerosol (SOA).To enhance our understanding of cold-start emissions and their potential to form SOA, measurements of approximately 21,000 cold starts were carried out inside an underground parking garage from November 29 to December 24, 2024. The garage consists of 250 parking spaces and is located beneath a shopping mall in Patras, Greece. The particle phase was measured by a scanning mobility particle sizer (SMPS) and further characterized using a high-resolution aerosol mass spectrometer (HR-ToF-AMS) and a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) coupled to a CHARON inlet. Black carbon was quantified by an Aethalometer (AE33). Gas-phase composition was measured with the PTR-MS, while inorganic trace gases including NO, NO2, CO, CO2, O3, and SO2 were continuously monitored. Tenax tubes were also collected from the garage ambient air for offline GC-MS analysis. Additionally, the traffic flow was recorded at both the entrance and exit of the garage. The SOA formation from vehicle emissions was investigated using an oxidation flow reactor (OFR) under controlled OH exposures by varying combinations of the reactor’s UV lamps.The measurements of the traffic and the concentrations were combined to derive average emissions of gas and particulate phase pollutants. The estimated cold start emission factors were then compared to those reported in the Dutch Εmission Inventory. Within the OFR, organic aerosol concentrations increased from four to eleven times depending on OH exposure, with the production of highly oxygenated organic compounds. Aromatic compounds were identified as the dominant precursors of SOA.

Abstract. Secondary organic aerosol (SOA) is a major component of particulate matter but is often underpredicted in chemistry climate models. Recent advances in measuring and resolving the chemically complex structure of intermediate volatile organic compounds (IVOC) have shown that IVOCs, despite their high SOA yields, have long been underrepresented in models. These compounds are key precursors of SOA from emissions in the road transport sector and significantly influence SOA formation. Understanding vehicle emissions, their chemistry, and their SOA-forming potential is essential for accurately estimating their contributions to atmospheric SOA and global organic aerosol loads. To improve this understanding, we have updated the organic module ORACLE in the global chemistry climate model EMAC. The existing IVOC representation was based on scaled organic carbon (OC) emissions and a highly parameterized volatility basis set (VBS) which underestimated global IVOC emissions, particularly those from gasoline combustion, and oversimplified their chemistry. Here, we replaced this approach with a lumped species framework, in which experimental data for gasoline and diesel emissions were grouped into seven lumped species based on their chemical properties and hydroxylation potentials. These species were linked to adjusted emission inventories for regional diesel and gasoline consumption. A 10 year simulation with the updated ORACLE-IVOC model resulted in significant changes. The global atmospheric burden of road transport IVOC-derived SOA (SOA-iv) increased by 1 order of magnitude, from 0.014 to 0.13 Tg. The composition of road transport organic aerosol (OA) shifted, with SOA-iv contributing 2.5 to 13 times more than the primary organic aerosol (POA) and SOA derived from semi-volatile organic compounds combined. In the results using the previous model, this ratio was between 0.4 and 1.1. The geographical distribution of OA also changed. Regions rich in gasoline relative to diesel emissions experienced higher concentration increases, and remote areas experienced elevated concentrations due to more efficient long-range transport of the new lumped IVOC species. Overall, these changes led to a significant increase in the contribution of road transport to total anthropogenic SOA-iv from an average value of 3 % to 35 %.

This study evaluated polyhydroxyalkanoates (PHAs) production from a medium corresponding to the condensate derived from food waste drying, using a mixed microbial culture in a 15 L Sequencing Batch Reactor (SBR). The reactor operation comprised two distinct periods to investigate the impact of varying organic loading rates on biomass performance and polymer accumulation. In Period 1, when the soluble Chemical Oxygen Demand (sCOD) was 6.8 ± 1.4 g/L, efficient nitrogen limitation promoted complete urea consumption and stable biomass growth, yielding higher intracellular PHA accumulation (11.74 ± 6.01%). The microbial community exhibited a balanced copolymer production (HB:HV ratio of approximately 54:46). Conversely, Period 2, characterized by higher organic loads (sCOD 12.1 ± 2.9 g/L), displayed incomplete urea utilization, reduced biomass viability, and significantly lower PHA accumulation (5.26 ± 2.53%). A second set of experiments aiming at the assessment of the impact of operation mode (with and without inclusion of a settling phase) demonstrated that removal of settling leads to a stable long-term steady-state operation with enriched PHA-accumulating bacteria and increased polymer storage capacity.

The employment ofthe metal-ion-assisted [1+1] Schiff-base condensationhas led to complexes [Ln­(LN5)­(Ph3SiO)2]­(PF6), where LnIII = DyIII (1-Dy) and HoIII (1-Ho), with close-to-ideal D5h local symmetry. For the Kramers DyIII system, slow magnetization relaxation was observed up to 64 K yieldinga sizable Ueff value of 963 K, whereasthe non-Kramers HoIII compound exhibited no out-of-phasesignals at T > 2 K. Single-crystal magnetic hysteresismeasurements uncovered the magnetization blockage of 1-Dy at T < 4 K with typical butterfly shaped loops,while open rectangular-shaped hysteresis loops were observed for 1-Ho below 0.2 K. Doping of the 1-Ho compoundinto a diamagnetic YIII matrix unveiled the hyperfine-drivenQTM steps reflected by staircase-like hysteresis loops for 1-Ho@Y. Detailed analysis through ab initio calculations has shed lighton the low-lying energy levels of both compounds leading to well-isolatedand pure ground states of mJ = ±15/2 and mJ = ±8 for 1-Dy and 1-Ho, respectively.The magnetization relaxation for 1-Dy advances throughthe third excited state, whereas the significant tunnel splitting(Δtun) of ∼0.15 cm–1 inthe ground state of 1-Ho has fostered the onset of fasttunneling relaxation.

This study investigates the enhancement of damping properties in carbon fiber-reinforced polymer (CFRP) composites by incorporating graphene nanoplatelets (GNPs) into the epoxy matrix. Epoxy and CFRP specimens with varying GNP concentrations, were developed and tested through free vibration experiments to measure damping ratios. Additionally, a computational model based on the finite element method was developed to simulate the damping behavior of these hybrid nanocomposites. Using periodic representative volume elements under sinusoidal axial loads, the model accurately predicted damping performance by calculating the time lag between applied loads and resulting deformations. Comparison of numerical results with experimental data revealed a strong correlation, confirming the model's effectiveness in capturing the influence of GNP mass fraction on damping enhancement.

The biological treatment of second cheese whey (SCW) was investigated using two different marine cultures, the microalgae Picochlorum costavermella and the cyanobacterium Geitlerinema sp. Seawater from the coastal area of Rio, near Patras, was used for dilution of the SCW to achieve an initial concentration of about 2000 mg d-COD/L in both cases without any external additions of the inorganic nutrients N and P. The growth of the mixed biomass, the removal of nutrients and the simultaneous accumulation of bioproducts over time were studied, with d-COD removal reaching 65% and maximum lipid and protein contents, up to 24% and 41.7%, respectively.