Sample Material Research Articles

Hyperspectral Imaging for Detecting Plastic Debris on Shoreline Sands to Support Recycling

Environmental pollution from plastic debris is raising concerns not only for the vulnerability of marine species to ingestion but also for potential human health hazards posed by small particles, known as microplastics. In this context, marine areas suffer from a lack of constant shoreline cleanups to remove accumulated debris, preventing their degradation and fragmentation. To establish optimal strategies for streamlining plastic recovery and recycling operations, it is important to have a system for recognizing plastic debris on the beach and, more specifically, for identifying the type of polymer and mapping (e.g., topologically assessing) the distribution of plastic debris on shoreline sands. This study aims to provide an operative tool finalized to perform an in situ detection, analysis, and characterization of plastic debris present in the coastal environment (i.e., beaches), adopting a near-infrared (NIR)-based hyperspectral imaging (HSI) approach. In more detail, the possibility of identifying and classifying polymers of plastic debris by NIR-HSI in three different areas along the Pontine coastline of the Lazio region (Latina, Italy) was investigated. The study focused on three distinct beaches (i.e., Foce Verde, Capo Portiere, and Sabaudia), each characterized by a different type of sand. For each location, the adopted approach allowed for the systematic classification of the various types of plastic waste found. Three Partial Least Squares Discriminant Analysis (PLS-DA) classification models were developed using a cascade detection strategy. The first model was designed to distinguish plastics from other materials in sand samples, the second to detect plastic particles in the sand, and the third to classify the type of polymer composing each identified plastic particle. Obtained results showed that, on the one hand, plastics were correctly detected from sand and other materials (i.e., sensitivity = 0.892–1.000 and specificity = 0.909–0.996), and on the other, the recognition of polymer type was satisfactory, according to the performance statistical parameters (i.e., sensitivity = 1.000 and specificity = 0.991–1.000). This research highlights the potential of the NIR-HSI approach as a reliable, non-invasive method for plastic debris monitoring and polymer classification. Its scalability and adaptability suggest possible future integration into mobile systems, enabling large-scale monitoring and efficient debris management.

RECEIVING AND ADSORPTION CHARACTERISTICS OF BIOCARBON MATERIALS FROM HOUSEHOLD WASTE

The aim of this research is the development of new carbon materials based on agricultural waste and a detailed study of their physicochemical properties, which allows to evaluate the potential directions of use of these materials in industry and environmental technologies. Within the framework of the work, four types of waste were chosen, in particular, wood sawdust, apple cake, as well as wheat and corn husks, which are widely available and rarely used as raw materials for creating adsorbents. The selected materials were subjected to the process of pyrolysis at a temperature of 500°C for one hour, which effectively preserves the porous structure of the material and improves its adsorption properties. The obtained samples of biocarbon materials were analyzed using nitrogen porosimetry, which made it possible to determine their adsorption potential, porosity, and total surface area. The results of the study showed a significant difference in the adsorption capacity of the samples, depending on the type of raw material. The sample based on corn husk demonstrated the highest adsorption activity, which indicates its potential for water purification from various types of pollution, including organic and inorganic compounds, heavy metals and other toxic substances. In addition, an additional analysis of the samples was carried out in order to assess their potential in other industries. In particular, the revealed porosity and surface area of ​​the materials allow us to consider them as promising components for filtration systems, catalysts in chemical reactions, materials for energy storage, as well as means for environmental protection and environmental restoration. The results of the study confirm that the use of agricultural waste for the creation of functional carbon materials is not only economically beneficial, but also an ecologically appropriate approach, which contributes to reducing the amount of waste and creating new opportunities for sustainable development.

Assessment of mycotoxins in infant flour and their decontamination in raw material during production processes in Ouagadougou.

The infant flours produced in Burkina Faso are essentially a mixture of cereals and legumes. These raw materials are frequently contaminated with mycotoxins which pose a huge food safety and public health threat. The objective of this study was to determine mycotoxin levels in raw materials and infant flours in Ouagadougou and to investigate the impact of decontamination on the raw materials used in infant flour production. A total of 22 cereals and 17 legumes as raw materials and 26 infant flour samples were analysed for aflatoxins, fumonisin B1 (FB1), and ochratoxin A (OTA) by liquid chromatography coupled to tandem mass spectrometry, while saline treatment and hand-sorting of grains in mycotoxin reduction were tested. All the samples of raw materials and infant flours were contaminated with aflatoxins, whereas 20.5% and 38.5% of raw materials and 57.7% and 61.5% of infant flours, respectively, were contaminated by FB1 and OTA. These decontamination assays significantly reduced the levels of mycotoxins. AFB1 was reduced by 48% after soaking of maize for 6h in a 6% NaCl solution. Sorting resulted in a 92% reduction in AFB1 content in peanut. However, soaking in saline solution did not reduce the FB1 and OTA contents. Sorting did not also reduce FB1 contents in peanut. Sorting and soaking in 6% saline solution for 6h are production processes that lead to a reduction in the level of contamination by aflatoxins in maize and peanut used as raw materials for infant flour production.

Cranial morphology and phylogenetic reassessment of Barreirosuchus franciscoi (Crocodylomorpha, Notosuchia), a Peirosauria from the Late Cretaceous of Brazil.

With nearly 30 living species of relatively similar ecological traits, Crocodylomorpha is represented today by only a small fraction of its past diversity. The well-documented crocodylomorph fossil record has revealed more than 500 taxa, with much higher ecological and morphological diversity than their extant counterparts. An example of such astonishing diversity is the Late Cretaceous rocks of the Bauru Group (southeast Brazil), from which numerous taxa are known, belonging to the clade Notosuchia. These were predominantly terrestrial taxa, some of which exhibited traits associated with omnivorous or even herbivorous feeding behaviors, such as Sphagesauridae, whereas others were adapted to a carnivore diet, such as Baurusuchidae and Peirosauridae. Among these is Barreirosuchus franciscoi, originally described as a neosuchian (Trematochampsidae) but later interpreted as a peirosaurid notosuchian. Even though included in recent morphological and phylogenetic analyses, B. franciscoi still lacked a more detailed description. Here, we provide an in-depth description of the cranial elements of B. franciscoi, using data from computed tomography and a broad sample of comparative material, including living and fossil crocodylomorphs. Also, the neuro-cavities, including the endocast, nasopharyngeal duct, and the olfactory region, were digitally reconstructed. Finally, a new phylogenetic analysis recovered B. franciscoi nested within Peirosauria, forming the Itasuchidae clade with other potentially semiaquatic species: Rukwasuchus yajabalajekundu, Pepesuchus deiseae, and Itasuchus jesuinoi. The morphological and phylogenetic reassessment of B. franciscoi indicates a semiaquatic form, highlighting the ecological diversity of notosuchians from the Bauru Group as well as the capacity of notosuchians to explore a myriad of environments.

Luminous Efficiency Determination of Spacecraft Materials in Ground Test Facilities

This paper reports the approach to determine the luminous efficiency of spacecraft materials experimentally. The idea is that knowing the luminous efficiency of spacecraft materials allows for deriving mass estimates from observation data linking meteor science methods to man-made artificial meteors. This way, observation data from airborne missions and known ground-based meteor observation networks become a versatile tool to analyze destructive spacecraft entry. Material samples were scaled to a typical re-entry condition. The authors recently developed a method to determine the radiant flux in the passbands U, B, and V and the corresponding color indices. The measured mass loss during the experiment is used to determine the luminous efficiency τ for the different passbands. These values are reported for three different materials under flow conditions corresponding to two trajectory points at altitudes of 70km and 65km in a typical decaying re-entry orbit. The resulting luminous efficiency values are of the order 10-5, which is about two orders of magnitude lower than meteoroid efficiencies. The found data is applied to fragments observed during the CYGNUS OA-6 observation campaign. The mass loss was extrapolated for the entire duration of the re-entry resulting in a mass of around 68-80% of literature values for the mass at the entry interface.

Gadolinium doped lithium aluminum borate [Li3Al3(BO3)4:Gd] materials synthesized and characterized for its structural, optical and thermoluminescence properties for use in dosimetric application

Lithium aluminum borate materials was made ready for dosimetric uses in radiation processes. In order to enhance the structural and dosimetric qualities, varying mole concentrations of gadolinium were added to samples of lithium aluminum borate materials. High temperature solid-state technique was used in producing the lithium aluminum borate material. The characterization of the material was archived by using Scanning electron microscope, X-ray diffractometer, thermal gravimetric evaluation, UV-vis-NIR spectrophotometer and thermoluminescence reader/irradiator in other to determine for their structural, thermal analysis, optical properties and dosimetric properties respectively. The kinetic analysis of the major glow peak yielded the activation energy. The crystalline sizes of the undoped and gadolinium-doped Li3Al3(BO3)4 materials were reported to be approximately 36.38 nm and 68.84 nm, respectively, which relies on their matching peaks at a 2θ angle of 25.79o. The grain size for the undoped and gadolinium doped lithium aluminum borate were found within a given range of values 140 – 160 nm, and 80 – 100 nm respectively. The optical energy band gap was found within 3.90 eV to 4.35 eV for the gadolinium doped while the undoped is 3.00 eV for lithium aluminum borate respectively. A larger energy band gap of lithium aluminum borate was observed after gadolinium was incorporated as dopant. The phosphor of lithium aluminum borate doped with gadolinium was observed to exhibit prominent TL intensity peaks at 100 oC following irradiation. The irradiated samples of lithium aluminum borate doped with gadolinium showed a dose response that was linear between 20 and 150 Gy. This work demonstrates the potential use of Gd-doped lithium aluminum borate phosphor in radiation dosimetry.

Angle of polarized light (AOP) Property for optical classification of the crosslinked polymer

Light-matter interaction has been profoundly studied for sample material classification. However, the optical classification of the sample through the polarized light-matter interaction remains underexplored. It is limited to the measurement of intensity instead of the angle of polarized light (AOP) for its degree of polarization. Measurement of the degree of polarization within a material or a medium becomes easier with a simple, low-cost and direct measurement without the need of any probing or labelling agent. Thus, this investigation was conducted mainly to determine the angle of polarized light (AOP) property of the crosslinked polymer using our proposed polarization measurement technique as an alternative approach of the material classification. The angle of polarized light (AOP) of each polymer was determined in combination property of polarization by absorption, transmission, and scattering. Our proposed scattered angle (ס=90°, 100°, 110°, and 120°) successfully measured the AOP of each polymer that can be classified into two groups. Group 1 represents the AOP value (aopt1-aopn) for a test sample oft1 = 3.1 %, 3.2, and 3.3 % with comparison to the normal sample (n = 3.0 %) and Group 2 represents the AOP value (aopt2-aopn) for the test sample oft2 = 3.4 %, 3.6 % and 3.7 % with comparison to the normal sample (n = 3.0 %). Our study proved a direct, easy, and simple method of determining the degree of polarization of the polymers without the need of complex formulation and labelling protocol. Therefore, this work may enhance the investigation of the optical properties of the agarose-based tissue-mimicking phantom (AGTMP) for modeling or simulation of the real biological sample in the future. Our polarization measures are worthy of further explored and implemented in current optical imaging techniques or sensing platform for optical classification of the biomaterials.

Effect of cigarette smoking on the optical properties of contemporary dental ceramics: an in-vitro analysis.

Cigarette smoking is the most common form of tobacco use worldwide. With the frequent introduction of new dental materials, the effect of smoking on their optical properties such as long term color stability, should to be thoroughly investigated. This in-vitro study aims to investigate the effect of smoking on the optical properties of contemporary dental ceramics used currently for restoration of teeth. Five different materials in two shades (B1 and C1) were used with 15 samples from each pressable lithium disilicate (Emax), layered lithium disilicate (Lmax), porcelain fused to metal (PFM), monolithic zirconia (MZr) and layered zirconia (LZr) were used (n=75). The samples were exposed to conventional cigarette smoke and color stability was assessed at four different time intervals i.e., baseline, 1 week, 1 month and 6 months. CIELAB color space (CIE L*a*b*) values were used to evaluate the color difference (ΔE). A one-way analysis of variance (Anova) was used for statistical analysis of ΔE. Significant P-value was kept as <0.05, followed by Tukey post-hoc test. All test materials demonstrated significant color differences (ΔE) after exposure to cigarette smoke (p<0.05). For shade B1, the highest change in shade ΔE 17.02 was exhibited by Lmax, whereas the least change in shade was exhibited by Emax followed by PFM at values of ΔE 10.11 and 11.2 respectively. For shade C1, the highest change (11.47) in shade at 6 months was demonstrated by MZr, whereas lowest values of ΔE were exhibited by Emax (7.52). Traditional smoking causes significant change in shade of dental ceramics which can affect the esthetics of the patients. All material samples tested showed the values of ΔE > 3.3 which is higher than the acceptable range. Lowest color change was observed in Emax and PFM.

Disequilibrium in natural decay series in samples from Czech water treatment plants: Uranium, radium and thorium isotopes determination

In the Czech Republic, underground or mixed source water treatment plants are classified as the workplaces with possible increased exposure from a natural source of radiation. When releasing waste materials or residues from these NORM workplaces into the environment, the content of natural radionuclides is measured and compared with the clearance levels established by Czech legislation. The content of natural radionuclides in solid samples is determined primarily by high-resolution gamma-ray spectrometry. Six radionuclides, 238U, 228Th, 226Ra, 228Ra, 210Pb, 40K, are measured directly or by their measurable decay products (assuming equilibrium), the activity concentration of the other four radionuclides, 234U, 230Th, 210Po, 232Th is conservatively estimated. The study is focused on mapping the properties of NORM arising from the treatment of groundwater and, based on the real samples measurement, verification of new proposed assessment approach. It was tested whether the knowledge of the content of natural radionuclides in water can be practically used to estimate the content in NORM. Samples of water, filter material or sludge were taken from 16 different water treatment plants. Combination of gamma-ray spectrometry and radiochemical methods were applied to determine the content of radionuclides 234U, 238U, 226Ra, 228Ra, 228Th, 230Th and 232Th in solid NORM, and radionuclides 234U, 238U, 226Ra, 228Ra in water. Based on the results the proposed modification of the assessment was verified.

Assessment of landscape impact on snow chemical composition in terms of mineral geochemical exploration

In areas with cold climate seasonal snowpack is an attractive sampling material for geochemical exploration of deep mineral accumulations. However, previous studies on assessment of exploration efficiency of snow cover have paid little attention to snow composition variability conditioned by local landscape structure.The layered sampling of snow sections was performed in different landscape settings of the local area. The research area is characterized by the absence of ore mineralization zones and low anthropogenic load. The physical-chemical parameters and concentration of wide range of elements were identified in snowmelt. Multi-component data was integrated by means of factor principal component analysis. Besides, additive and differential geochemical indexes were used. The classification snow models were developed using hierarchical cluster analysis. The variance of chemical elements distribution and factor models of geochemical pattern were compared before and after reduction of background fluctuation. In terms of variation coefficient values of chemical elements the area has background parameters of chemical inhomogeneity. In total variance a lateral component prevails over a vertical one. The highest concentrations of chemical elements were found in snow section of forest landscape. It is necessary to take into account the fact of geochemical background fluctuation when interpreting the data of metal assay snow survey.After the reduction of lateral geochemical background fluctuation, the factor model has better classified the chemical elements in terms of their connection with soluble and insoluble occurrence forms. The values of differential index of liquid and solid phases have a similar satisfactory vertical variability in different landscapes. The analysis of chemical elements concentration reveals snow horizons that were or are affected by thaw and percolating water. The snow bottom layer, which is sampled at geochemical exploration, is not strong influenced by elution.

Scanning Microwave Impedance Microscopy for Characterization of Graphene Systems Encapsulated by Hexagonal Boron Nitride

Scanning microwave impedance microscopy (sMIM) is a near‐field technique that enables the characterization of conductive materials with a resolution down to 1 nm. In hexagonal boron nitride (hBN)‐encapsulated devices, microwaves emitted from the sMIM tip penetrate and reach with the underlying 2D materials, allowing for the mapping of local conductivity variations. Using twisted bilayer graphene, it is demonstrated that this technique can characterize moiré patterns through hBN flakes up to 2.5 nm thick. Additionally, it is showed that sMIM can distinguish between conductive and insulating materials in samples encapsulated by hBN layers exceeding 15 nm. A key finding is that signal decay due to encapsulation is intrinsically linked to the tip's condition. This work overcomes limitations in the application of twistronics, enabling the verification of the periodicity of moiré patterns in high‐quality encapsulated devices between electrical contacts.

Local and Regional, Not Latitudinal, Variation in Microclimate and Bedrock Shapes Moss‐Associated Diatom Communities in Greenland

ABSTRACTAimGreenland is among the most rapidly changing regions on Earth, with climate change having a profound impact on its terrestrial ecosystems. Here, moss‐associated diatoms hold great potential as sensitive biological indicators to monitor responses to climate change, but their diversity, community structure and biogeography remain virtually unexplored. Our study, thus, aims to (1) explore the diversity and community structure of moss‐associated diatoms in Greenland and (2) assess the environmental and spatial variables driving their geographic distribution, establishing a baseline for their use as bio‐indicators of climate change.LocationGreenland, spanning a gradient from high to subarctic regions.TaxonMoss‐associated diatoms (Bacillariophyta).MethodsLM and SEM analysis was conducted on 175 terrestrial moss samples collected from preserved herbarium material and fresh samples (1988–2021) from high, low and subarctic localities in Greenland. Biogeographical distributions, biodiversity patterns and community structure were examined in relation to environmental and spatial factors using Kruskal–Wallis, Spearman's Rank, ordination, SIMPROF and variation partitioning analyses.ResultsA total of 544 diatom taxa (66 genera) were identified, with nearly half potentially new to science. Community structure was predominantly influenced by moisture, pH, conductivity and temperature. Local variation in microclimate and bedrock, thus, explained more variation in the diatom communities than latitude‐related environmental gradients. Surprisingly, temperature had a negative impact on diatom richness, probably due to its adverse effect on moisture, highlighting the vulnerability of Arctic moss diatoms to global warming.Main ConclusionsThis study provides the first comprehensive analysis of Greenland's moss‐associated diatoms, highlighting their high diversity and sensitivity to environmental changes. Our findings underscore their potential as indicators for monitoring climate change in the Arctic, with moisture, pH, conductivity and temperature being critical factors influencing their communities, laying the groundwork for future research and monitoring efforts.

Development and Evaluation of Regolith Mass Estimation Sensor Based on Photoresist Effect

This paper presents the design, implementation, and laboratory validation of an optoelectronic-based mass estimation sensor for regolith sampling devices. The sensor integrates multiple photoresistors into the walls of a shovel of a sampling device, where the sensors detect varying levels of light occlusion caused by the deposited regolith. By analyzing the output signals from these photoresistors, the sensor estimates the mass of the sampled regolith. The device is designed to handle a typical sample mass range of 100–300 g. Laboratory tests demonstrated that the sensor can estimate the regolith mass with a relative error of approximately 23%, which is suitable for early-stage applications where rapid, non-invasive mass estimation is essential. The shown level of accuracy underscores the potential for further refining the calibration process, enhancing sensor sensitivity, and integrating multi-sensor approaches to improve performance. This conceptual study highlights the feasibility of using optoelectronic sensors for regolith mass estimation, paving the way for future innovations in ISRU missions and other granular material sampling applications. Future work will focus on the optimization of photoresistor placements, refining the calibration process, and enhancing sensor sensitivity to improve the accuracy of mass estimation.

Finite element modelling of atomic force microscopy imaging on deformable surfaces.

Atomic force microscopy (AFM) provides a three-dimensional topographic representation of a sample surface, at nanometre resolution. Computational simulations can aid the interpretation of such representations, but have mostly been limited to cases where both the AFM probe and the sample are hard and not compressible. In many applications, however, the sample is soft and therefore deformed due to the force exerted by the AFM tip. Here we use finite element modelling (FEM) to study how the measured AFM topography relates to the surface structures of soft and compressible materials. Consistent with previous analytical studies, the measured elastic modulus in AFM is generally found to deviate from the elastic modulus of the sample material. By the analysis of simple surface geometries, the FEM modelling shows how measured mechanical and topographic features in AFM images depend on a combination of tip-sample geometry and indentation of the tip into the sample. Importantly for the interpretation of AFM data, nanoparticles may appear larger or smaller by a factor of two depending on tip size and indentation force; and a higher spatial resolution in AFM images does not necessarily coincide with a more accurate representation of the sample surface. These observations on simple surface geometries also extend to molecular-resolution AFM, as illustrated by comparing FEM results with experimental data acquired on DNA. Taken together, the FEM results provide a framework that aids the interpretation of surface topography and local mechanics as measured by AFM.

Moving toward automated µFTIR spectra matching for microplastic identification: addressing false identifications and improving accuracy

Infrared spectroscopy is a widely used tool for studying microplastics and identifying microparticles. Researchers rely on spectral libraries to differentiate between synthetic and natural materials. Unfortunately, spectral library matching is not perfect, and best practices require researchers to use time consuming, manual peak matching to assess spectral matches. Moving toward automated matching requires increased confidence in the matching process. Using spectra matching software may increase the efficiency of particle identification, however some matching strategies may confuse natural materials such as cotton, silk, and plant matter with common classes of synthetics such as polyesters and polyamides. In this experiment, we prepared 22 pristine sample materials from natural and synthetic sources and measured micro-Fourier transform infrared (µFTIR) spectra in transmission mode for each sample using a Thermo Nicolet iN10 MX instrument. The collected spectra were then input into two spectral library matching systems (Omnic Picta and Open Specy), using a total of five identification routines. Next, we placed a subset of four pristine microplastic materials in a biologically active river system for two weeks to simulate environmental samples. These simulated environmental samples were processed using 10% hydrogen peroxide for 24 h to remove organic contamination and then identified using the strongest performing library. We found that libraries with fewer sample spectra produced lower correlation matches and that using derivative correction greatly reduced the number of inaccuracies in identifying materials as either natural or synthetic. We also found that environmental fouling reduced the correlation value of library matches when compared to pristine particles, however the effect was not consistent across the four materials tested. Overall, we found that the accuracy of automated library matching in the tested systems and processing routines varied from 64.1 to 98.0% for distinguishing between natural and synthetic materials, and that a high Hit Quality Index (HQI) did not always correlate with accuracy. These results are important for the microplastic field, demonstrating a need to rigorously test spectral libraries and processing routines with known materials to ensure identification accuracy.

Challenges and Performance of Filter Dusts as a Supplementary Cementitious Material.

Global industry relies on a linear approach for economic growth. One step towards transformation is the implementation of a circular economy and the reclamation of anthropogenic deposits. This study examines two filter dusts, one German and one Argentinian, from the production of calcined clays, representing such deposits. Investigations and comparisons of untreated and calcined filter dust and the industrial base product pave the way for using waste product filter dust as supplementary cementitious material (SCM). In the future, some twenty thousand tons of contemporary waste could potentially be used annually as SCM. The results confirm the suitability of one material as a full-fledged SCM without further treatment and a measured pozzolanic reactivity on par with fly ash. Sample materials were classified into two groups: one was found to be a reactive pozzolanic material; the other was characterized as filler material with minor pozzolanic reactivity. Additionally, important insights into the physical properties of oven dust and heat-treated oven dust were obtained. For both material groups, an inversely proportional relationship with rising calcination temperatures was found for the specific surface area and water demand. The impact of the calcination temperature on both the particle size distribution and the potential to optimize the reactivity performance is presented.

Novel dissolved organic 14C analyses method applied in a case study at a LILW waste repository

Abstract A routine chemical procedure was developed at the Ede Hertelendi Laboratory of Environmental Studies (HEKAL), in Debrecen which can measure the dissolved organic radiocarbon content of groundwater as well as the inorganic and total fraction. The typical background of this non-purgeable dissolved organic radiocarbon preparation is 0.73 ± 0.14 percent modern carbon (pMC), using a carbon contamination correction on fossil dissolved material (potassium hydrogen phthalate) samples.

Effect of temperature and capillary number on wettability and contact angle hysteresis of various materials. Modeling taking into account porosity

The effect of surface temperature and laser texturing on the wettability and contact angle hysteresis of Cu, Cu/G, AlMg3, Cu-SiC was considered. Modeling using molecular dynamics qualitatively confirms the experimental results: 1) an increase in the contact angle hysteresis on a textured surface; 2) influence of the surface wettability on contact angle hysteresis; 3) influence of the contact line velocity on contact angle hysteresis. Heating the sample of different composite materials can lead to either an increase in the contact angle or a decrease. It was shown that after laser texturing, a system of nano-micro pores was formed in the surface layer of the material, which leads to an abnormally high contact angle hysteresis on the Cu-SiC composite. A new model is proposed that explains the different qualitative behavior of the contact angle hysteresis in different studies with increasing capillary number (Ca), as well as with increasing sample temperature.

Corporate Tax Aggressiveness and Managerial Capabilities: Insights From Indonesian Firms

This study aims to investigate the effect of management ability, business strategy, and profitability on corporate tax aggressiveness. This study uses mediation analysis with the Smart PLS approach on a sample of basic materials sector companies listed on the IDX from 2020 to 2022. The results show that more capable management tends to adopt a conservative approach in tax management practices. In addition, business strategies such as prospector and defender have a significant impact on tax aggressiveness. More profitable companies tend to implement more aggressive tax strategies. Companies need to improve managerial capabilities to manage taxes more effectively, as well as formulate appropriate business strategies to mitigate tax risks in the future. With a better understanding of tax risks, companies can minimize potential tax disputes and protect their reputation and long-term performance. This study extends the research time scope to 2022 and uses corporate governance mechanisms as moderating variables, both internal and external, which have not been widely studied in previous studies.

Optically accessible, 3D-printed flow chamber with integrated sensors for the monitoring of oral multispecies biofilm growth in vitro.

The formation of pathogenic multispecies biofilms in the human oral cavity can lead to implant-associated infections, which may ultimately result in implant failure. These infections are neither easily detected nor readily treated. Due to high complexity of oral biofilms, detailed mechanisms of the bacterial dysbiotic shift are not yet even fully understood. In order to study oral biofilms in more detail and develop prevention strategies to fight implant-associated infections, in vitro biofilm models are sorely needed. In this study, we adapted an in vitro biofilm flow chamber model to include miniaturized transparent 3D-printed flow chambers with integrated optical pH sensors - thereby enabling the microscopic evaluation of biofilm growth as well as the monitoring of acidification in close proximity. Two different 3D printing materials were initially characterized with respect to their biocompatibility and surface topography. The functionality of the optically accessible miniaturized flow chambers was then tested using five-species biofilms (featuring the species Streptococcus oralis, Veillonella dispar, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis) and compared to biofilm growth on titanium specimens in the established flow chamber model. As confirmed by live/dead staining and fluorescence in situ hybridization via confocal laser scanning microscopy, the flow chamber setup proved to be suitable for growing reproducible oral biofilms under flow conditions while continuously monitoring biofilm pH. Therefore, the system is suitable for future research use with respect to biofilm dysbiosis and also has great potential for further parallelization and adaptation to achieve higher throughput as well as include additional optical sensors or sample materials.