Glass Microfiber Filter Research Articles

First report on the long-term viability of Acanthamoeba species in unpreserved environmental freshwater samples stored at room temperature

ABSTRACT Acanthamoeba is an opportunistic, free-living amoeba ubiquitous in the environment. Despite reports of its wide distribution in the Philippines’ freshwater resources, more information on the long-term viability of the Acanthamoeba species is needed. This study aimed to define the long-term viability of Acanthamoeba species in unpreserved environmental freshwater samples after 3 years of storage at room temperature. Stored water samples from 15 study sites were filtered through a 1.2-μm pore size glass microfiber filter, cultured in non-nutrient agar (NNA) lawned with Escherichia coli, and observed for amoebic growth for 14 days using light microscopy. Isolates from positive NNA culture were subjected to polymerase chain reaction (PCR) using JDP1 and JDP2 Acanthamoeba-specific primers. The study site positivity was 33% (5/15). Acanthamoeba genotype T4 and Acanthamoeba lenticulata were isolated from Luzon; Acanthamoeba divionensis was isolated from Visayas; and Acanthamoeba sp. and genotype T20 were isolated from Mindanao. The long-term viability of Acanthamoeba species is an added risk factor for the sustained contamination of aquatic resources and other sample matrices. This heightens the risk of transmission to humans and animals. This study demonstrated that water samples fated for Acanthamoeba studies can be stored unpreserved at room temperature for several years.

Electrochemical Performance and Characterisation of Chemically Treated Conductive PLA Fused Deposition Modelling (FDM) Current Collectors within Additively Manufactured (3D-Printed) Symmetric Carbon Supercapacitors

Within the fields of materials science, producing reliable, long-lasting, and efficient energy storage devices to meet the world’s energy needs remains a foremost research goal. 3D-printing (also known as Additive Manufacturing) provides many benefits to this research [1-8], allowing for excellent customization and freedom of design, while eliminating waste material in the manufacturing process. Wearable electronics, medical implants, and the Internet of Things will doubtless benefit from the advantages provided by additive manufacturing.Our previous work compared the electrochemical performances of symmetric carbon-based supercapacitor devices made using two 3D-printing techniques, SLA (stereolithography) and FDM (fused deposition modelling). Though possessing excellent cycle life, the conductive polylactic acid (PLA) FDM printed current collectors suffered from relatively high resistance and poor cyclic voltammetry curves (far from the rectangular shape of ideal electronic double-layer capacitors). This study aims to improve the conductivity of the FDM current collectors via chemically induced surface modification [9]. Both dimethylformamide (DMF) and aqueous potassium hydroxide (KOH) treatments are used for this purpose. The untreated, DMF-treated, and KOH-treated FDM current collectors are loaded with 1:1 by mass single-walled carbon nanotubes and graphene nanoplatelets carbon slurry, placed within stereolithography (SLA) 3D-printed casings [10], and assembled as supercapacitor cells (separated by glass microfiber filter separators soaked in 6 M aqueous KOH electrolyte).This works shows how DMF treatment method results in little change in electrochemical performance compared to the untreated FDM current collector cells, but pre-treatment in a solution of KOH identical to the cell electrolyte markedly improves the current collector conductivity. The KOH treatment provides a tenfold decrease in the FDM current collector resistance, which correlates with the improved cyclic voltammetric response. Galvanostatic charge-discharge tests reveal the effect of these treatments on specific capacitance, charge-discharge response, efficiency, and rate capability for these printed cells. The pre-treatment confirms that the cell electrolyte does not limited long term performance by interacting with the PLA current collector in 3D printed supercapacitor cells and tests using other inorganic active materials will also be shown.

Loss of micropollutants on syringe filters during sample filtration: Machine learning approach for selecting appropriate filters

Prefiltration before chromatographic analysis is critical in the monitoring of environmental micropollutants (MPs). However, in an aqueous matrix, such monitoring often leads to out-of-specification results owing to the loss of MPs on syringe filters. Therefore, this study investigated the loss of seventy MPs on eight different syringe filters by employing Random Forest, a machine learning algorithm. The results indicate that the loss of MPs during filtration is filter specific, with glass microfiber and polytetrafluoroethylene filters being the most effective (<20%) compared with nylon (>90%) and others (regenerated-cellulose, polyethersulfone, polyvinylidene difluoride, cellulose acetate, and polypropylene). The Random Forest classifier showed outstanding performance (accuracy range 0.81–0.95) for determining whether the loss of MPs on filters exceeded 20%. Important factors in this classification were analyzed using the SHapley Additive exPlanation value and Kruskal–Wallis test. The results show that the physicochemical properties (LogKow/LogD, pKa, functional groups, and charges) of MPs are more important than the operational parameters (sample volume, filter pore size, diameter, and flow rate) in determining the loss of most MPs on syringe filters. However, other important factors such as the implications of the roles of pH for nylon and pre-rinsing for PTFE syringe filters should not be ignored. Overall, this study provides a systematic framework for understanding the behavior of various MP classes and their potential losses on syringe filters.

Occurrence and Removal Efficiencies of Four Antibiotics in Kisii and Kabarnet Waste Water Treatment Plants, Kenya

Background: Antibiotics are presently considered as emerging contaminants with adverse effects in the environment and the population such as the development of antimicrobial resistant genes (ARG) and antimicrobial resistant bacteria (ARB). This study was guided by objective entailing to determine the seasonal occurrences and removal efficiencies of four antibiotics in Kisii and Kabarnet waste water treatment plants in Kenya. &#x0D; Place and Duration of Study: Waste water samples were picked from Suneka wastewater treatment plant in Kisii county and Kabarnet Level V Hospital in Baringo County Kenya in the months of June and December 2020&#x0D; Methodology: Multiple samples were picked in Kisii and Kabarnet waste water treatment plants in the months of June and December correspond to the dry and wet seasons in Kenya. Collected waste water samples were centrifuged and filtered with glass microfiber filter papers and subsequently passed through a Solid phase extractor cartridge. High Performance Liquid Chromatography was used for quantification of antibiotics as per international commission for harmonization and subsequently applied for analysis.&#x0D; Results: The results revealed that the dry season had higher antibiotic concentrations at 1.29, 0.09, 2.92 and 1.82 µg/l for sulphamethoxazole, trimethoprim, ampicillin and amoxicillin respectively for the Kisii waste water treatment plant and 0.18, 0.05, 1.34 and 0.09 µg/l respectively for Kabarnet waste water treatment plant. During the wet seasons the measured concentrations were 1.11, 0.14, 2.04 and 1.34 µg/l for sulphamethoxazole, trimethoprim, ampicillin and amoxicillin at the Kisii WWTP, and 0.14, 0.06, 1.01 and 0.09 µg/l for Kabarnet WWTP. The removal efficiencies in the WWTPs, ranged from a high of 94 % to a low of 11.11 % depending on the type of antibiotic in both wet and dry seasons.&#x0D; Conclusion: Amoxicillin, ampicillin, trimethoprim and sulphamethaxazole were found in both Kisii WWTPs and Kabarnet WWTPs with nearly all antibiotics having a higher concentration of in the dry season than in the wet season. The highest calculated percentage removal was 94.03 % while the lowest calculated percentage removal was 7.14 %. The results suggest that the two WWTPs are effective for the removal of different types of antibiotics.

Microplastics in the Danube River and Its Main Tributaries—Ingestion by Freshwater Macroinvertebrates

This study was carried out at the Danube River and its tributaries during the Joint Danube Survey 4 (JDS4) expedition. Three freshwater benthic species were used to estimate the quantity of microplastics (MPs): Corbicula spp., Limnodrilus hoffmeisteri (Claparede, 1862), and Polypedilum nubeculosum (Meigen, 1804). Following the kick and sweep technique, individuals were sampled using a hand net or dredge. In order to estimate the number of MP particles/individual particles/g wet body mass, the body mass and total length of all specimens were measured. Alkaline (Corbicula spp. and L. hoffmaisteri) and enzymatic (P. nubeculosum) protocols were performed for tissue degradation. All samples were filtered through glass microfiber filters (mesh size 0.5 µm). The particles were photographed, measured, and counted. A total of 1904, 169, and 204 MPs were isolated from Corbicula spp., L. hoffmaisteri, and P. nubeculosum, respectively. To confirm the chemical composition of isolated MPs, a subsample of 46 particles of the fragmented particles from 14 sampling sites was analysed via µ-ATR-FTIR spectroscopy analysis. The particles were characterised as polycarbonate (PC), polyethylene terephthalate (PET), polypropylene–polyethylene copolymer (PP-PE), nylon (polyamide-PA) and cellophane, with the domination of PET.

Phosphotungstic acid-coated glass fibre with thin Pd-sputtered films enhances fuel cell performance and durability in proton exchange membrane fuel cells (PEMFCs)

This study investigated the potential utilization of glass microfiber filters (GMFs) reinforced with hetero polyacid (12-phosphotungstic acid, H3PW12O40; PWA) in hydrogen fuel cells. Nano-sized PWA powders were confirmed through XRD and Raman spectra. Several analytical techniques confirmed the preservation of the Keggin structure of PWA following the absorption (interfacial contact) procedure using the dip-coating wetness method with water as the solvent. Proton conductivity under wet conditions exhibited a proportional increase with temperature. The research comprehensively explored the impact of the PWA membrane on microstructure, physicochemical properties, proton conductivity, and fuel cell performance. It was observed that the incorporation of Pd-decorated PWA enhances membrane mechanical strength, improves durability, and prevents membrane reduction from water contact, addressing PWA's high water solubility. Hydrogen fuel cells were constructed using both a pristine PWA membrane and a double-layered membrane (PWA/Pd). The PWA/Pd membrane demonstrated superior hydrogen fuel cell performance, achieving a higher maximum power density (MPD) of 16 mW cm−2 at a current density of 50 mA cm−2, compared to pristine PWA (1.03 mW cm−2) under identical conditions at 40 °C.

Detection of azadirachtin from neem kernels using a paper-based sandwich sensor.

In this work, a microfluidic paper-based analytical device (μPAD) was developed to detect the biopesticide azadirachtin (Aza) through a colorimetric assay. High precision estimation of Aza is classically carried out using high performance liquid chromatography (HPLC), which requires highly skilled personnel. Acidified vanillin is a commonly used colorimetric indicator in thin layer chromatography for detection of various phytochemicals. However, the assay involves concentrated acid, which limits the choice of paper substrates for paper-based sensors and raises safety concerns. In this work, we show how the assay can be extended from the liquid phase to a paper substrate. Glass microfiber (GMF) filter paper was found to be suitable paper as it was acid resistant; besides, its hydrophilicity enabled smooth flow of reagents. A microfluidic paper-based sensor (μPAD) was developed by sandwiching 5 mm sized GMF dots between two parafilm sheets. We demonstrate the use of colorimetric assay on the μPAD for on-site detection of Aza in neem kernels. The magenta color developed upon the reaction of acidified vanillin with Aza was captured using a smart-phone and analysed using RGB levels in the image. Calibration was established using neem kernel extract of known concentration. Linearity was seen in the concentration range of 5 to 25 mg L-1 Aza. A limit of detection of 2.3 mg L-1 was obtained using this method. The colorimetric assay showed a relative recovery of >85% when compared with the values obtained from HPLC. The stability of the reagents on the GMF sensor was investigated to understand the storage conditions and shelf life of the reagents and sensor. The present work demonstrates the development of a portable sensor for on-site detection of phytochemicals that can be an integral part of the agricultural supply chain.

Laser Ablation for Nondestructive Sampling of Microplastics in Single-Particle ICP-Mass Spectrometry.

In this work, laser ablation (LA) was characterized as a method for sampling and introducing microplastic particles (MPs) into an inductively coupled plasma (ICP) for subsequent 13C+ monitoring using an ICP-mass spectrometer operated in single-event mode. MPs of different types (PS, PMMA, and PVC) and sizes (2-20 μm) were introduced intactly. The laser energy density did not affect the particle sampling across a wide range (0.25-6.00 J cm-2). Single-shot analysis separated clustered MPs (2-7 MPs per cluster) during the LA and particle transport processes, allowing the temporally resolved analysis of the individual constituting MPs. Line scanning showed superior performance when using a small laser beam diameter combined with a high repetition rate. The 13C+ signal intensity correlated linearly (R2 >0.9945) with the absolute C mass in a 2-10 μm size range, while the use of He in the collision-reaction cell (CRC) allowed extension of the linear range to 20 μm. The LA approach generated narrower 13C+ signal distributions than the traditional solution-based approach (dry versus wet plasma conditions) and proved successful for the analysis of a mixed suspension (containing four sizes of PS MPs in a 2-5 μm size range) and for sampling MPs from PVDF and glass microfiber filters, with the latter offering a lower background.

Microplastic in fishes: the first report from a Himalayan River - Alaknanda.

The present study aimed to understand microplastic (MP) ingestion by five fish species with different feeding habits namely, Schizothorax richardsonii and Crossocheilus latius (herbivore),Cyprinus carpio (omnivore), Tor chelenoid (herbi-omnivore), and Botia horii (carnivore). The fishes were sampled from River Alaknanda (one of the headwaters of River Ganga) patch at Srinagar, Garhwal, Uttarakhand. The fish gut samples were digested with 30% hydrogen peroxide and vacuum filtered through glass microfiber filter. Each filter paper was observed microscopically to count MPs, and then, selected MPs were chemically characterized using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). The results revealed that all the species were contaminated with MPs and the rate of MP ingestion varied with feeding habits. The herbi-omnivore fish, Tor chelenoid, was observed to have the highest MP ingestion. Among the analyzed particles, fibers (66%) were the dominant type of MPs. The MPs were chemically characterized as High-Density Polyethylene (HDPE), Polypropylene (PP), and Polyester. This study contributes as a reference for the forthcoming researches, as it is the pioneer work on the ingestion of MP by fishes of a Himalayan River.

Indoor microplastics: a comprehensive review and bibliometric analysis.

Indoor microplastic (MP) pollution is becoming a worldwide issue because people spend more time inside. Through dust and air, indoor MP pollution may harm human health. This review summarizes recent advancements in indoor MP research, covering pretreatments, quality control, filter membranes, and identification methods. Additionally, it conducts bibliometric analysis to examine the usage of keywords, publication records, and authors' contributions to the field. Comparatively, dust and deposition samples exhibit higher MP concentrations than indoor air samples. Fiber-shaped MPs are commonly detected indoors. The color and types of MPs display variability, with polypropylene, polyethylene, polyethylene terephthalate, and polystyrene identified as the dominant MPs. Indoor environments generally demonstrate higher concentrations of MPs than outdoor environments, and MPs in the lower size range (1-100µm) are typically more abundant. Among the reviewed articles, 45.24% conducted pretreatment on their samples, while 16.67% did not undergo any pretreatment. The predominant filter utilized in most studies was the Whatman Glass microfiber filter (41.67%), and MPs were predominantly characterized using µ-FTIR (19.23%). In the literature, 17 papers used blank samples, and eight did not. Blank findings were not included in most research (23articles). A significant increase in published articles has been observed since 2020, with an annual growth rate exceeding 10%. The keyword microplastics had the highest frequency, followed by fibers. This indoor MP study emphasizes the need for collaborative research, policymaking, and stakeholder involvement to reduce indoor MP pollution. As indoor MP research grows, so are opportunities to identify and minimize environmental and health impacts.

Microextraction of electric fields and analytes by Janus hydrophobic/hydrophilic microfiber filter: Application in Raman detection of persistent organic pollutants in complex liquid environments

As one of the most pressing environmental issues, the prevention and control of persistent organic pollutants (POPs) continue to garner the attention of various fields. However, there is a lack of effective detection methods for trace amounts of POPs in sewage with a complex composition. To address this, a new Janus microextraction surface-enhanced Raman spectroscopy (SERS) strategy was explored in this study. By designing a Janus glass microfiber filter (GF) membrane structure with a superhydrophobic screening surface and a ZIF-8/Ag/GF detection surface, we demonstrated that POPs molecules in mixed sewage can be sensitively detected and specifically adsorbed and enriched. Thus, a concentration of p-aminothiophenol solution as low as 10−12 M was successfully detected with an enhancement factor as high as 5.16 × 109. Additionally, the collected Raman signal remained unimpeded by impurities such as dye molecules or sediment particles in sewage. Most importantly, the Janus GF substrate enabled the separation and detection of other POPs molecules such as PCB-77, perylene, and pyrene, indicating the immense potential of the Janus SERS strategy in the field of POPs detection.

Accelerated Capacity and Cycling Performance via Facile Instantaneous Precipitation Induced Amorphization for Lithium-Ion Batteries.

Conversion-alloying anodes have garnered escalating attention with high theoretical capacity, however, they are seriously hindered by large volume distortion and capacity fading. To counter, structural modification needs more exploration. Herein, advantageous structure and high-performance are realized in new amorphous PbSb2 O6 (PSO-a) nanosphere via facile instantaneous precipitation induced amorphization; conversion-alloying mechanism endows it with prominent lithium-storage capability; nanostructure can shorten ion-transfer distance and accommodate volume change outside the bulk of PSO-a; and loosely-stacked isotropic amorphous structure can enhance kinetics both at electrode/electrolyte interfaces and in the bulk. Volume change is synergistically stabilized from within to outside the bulk, leading to accelerated capacity and cycling. As expected, when employed in half-cells with 1 m LiPF6 in ethylene carbonate/diethyl carbonate/dimethyl carbonate/fluoroethylene carbonate (3:3:3:1 by mass) as electrolyte, glass microfiber filter as separator, and pure lithium foil as counter electrode, it realizes eminent performance with high specific capacity of 1512.6 mA h g-1 at 0.1 A g-1 and 755.1 mA h g-1 after 1000 cycles at 3 A g-1 . To the best of the authors' knowledge, this is the first time PbSb2 O6 is utilized as high-performance anode for lithium-ion batteries. Furthermore, this facile strategy provides a promising direction for high-performance amorphous anode material.

Free-standing conductive nickel metal-organic framework nanowires as bifunctional electrodes for wearable pressure sensors and Ni-Zn batteries

Free-standing metal-organic frameworks (MOFs) with controllable structure and good stability are emerging as promising materials for applications in flexible pressure sensors and energy-storage devices. However, the inherent low electrical conductivity of MOF-based materials requires complex preparation processes that involve high-temperature carbonization. This work presents a simple method to grow conductive nickel MOF nanowire arrays on carbon cloth (Ni-CAT@CC) and use Ni-CAT@CC as the functional electrodes for flexible piezoresistive sensor. The resulting sensor is able to monitor human activity, including elbow bending, knee bending, and wrist bending. Besides, the soft-packaged aqueous Ni-Zn battery is assembled with Ni-CAT@CC, a piece of glass microfiber filters, and Zn foil acting as cathode, separator, and anode, respectively. The Ni-Zn battery can be used as a power source for finger pressure monitoring. This work demonstrates free-standing MOF-based nanowires as bifunctional fabric electrodes for wearable electronics.

Characterization of aerosols from hemp-derived pre-roll joints

Objective Availability and consumer use of hemp products is rapidly increasing, but little work has been done to assess aerosol emissions of hemp pre-rolls. The objective of this research was to characterize the aerosol of pre-rolled joints from hemp material enriched for production of cannabigerol (CBG) that were smoked on a test system mimicking human use patterns. Materials and methods Aerosol emissions were collected and analyzed using glass microfiber filters and charcoal cartridges. The aerosol was screened for nine phytocannabinoids and 19 terpenes. Results Three phytocannabinoids (CBG, cannabichromene (CBC), and delta-9-tetrahydrocannabinol (THC)) were detected and quantified at a mean (SD) concentration of 19.4 (4.7), 0.48 (0.01), and 0.40 (0.04) mg per pre-roll, respectively. Five terpenes ((–)-α-bisabolol, (–)-guaiol, β-caryophyllene, nerolidol, and α-humulene) were detected and quantified at an average concentration of 352.7 (112.0), 194.3 (66.4), 106.0 (50.4), 28.3 (9.3), and 27.7 (11.2) µg per pre-roll, respectively. Particle size distribution testing via aerodynamic particle sizer and inertial impactor showed that average size of emitted aerosols was 0.77 (0.0) and 0.54 (0.1) µm, respectively. Conclusions This study describes methodology for characterization of cannabinoid and terpene dose in emitted aerosols and aerosolization efficiency from hemp pre-rolls. It also presents these data for one of the marketed products.

Outdoor Air Contaminants-Heavy Metals and Associated Health Risks in Duhok-Iraq

Toxic elements in the atmosphere can cause a variety of health and environmental problems. The current work aims to assess the concentrations of heavy metals associated with the air in the Duhok city-Kurdistan Region of Iraq. For the first time a low volume sampling pump with Glass Microfiber Filter paper was used. Forty samples of air filter aerosol particles were collected from several areas in the Duhok city, during the dry and rainy seasons. Samples of air filters were prepared by a microwave digestion system and assessed by inductively coupled plasma Optical-Emission Spectrometry (ICP-OES). The average concentrations of Cr, Zn, Ni, Cd, Fe, and Pb found in 20 sites in the study area for the dry season were 0.004 mg/m3, 0.007 mg/m3, 0.003 mg/m3, 0.002 mg/m3, 0.142 mg/m3, and 0.402 mg/m3 respectively. Also, the average levels of the mentioned elements were 0.003 mg/m3, 0.004 mg/m3, 0.012 mg/m3, 0.003 mg/m3, 0.138 mg/m3, and 0.645 mg/m3 respectively in wet season. Seasonal results confirmed no significant differences in the concentrations of elements measured at all study sites, with the exception of lead, which doubles during the rainy season. Results showed that the levels of metal concentrations in the present study exceeded the standard limits of WHO. The results of the health risk assessment showed that the population in Duhok city had a higher lifetime chance of developing cancer as a result of these air concentrations and their heavy metal content.

Detection of Acanthamoeba spp. in groundwater sources in a rural area in the Philippines.

Research on free-living amoebae (FLA) and its public health implication as an etiologic agent of parasitic infection in humans has recently gained traction in the Philippines. This study aimed to identify potential FLAs in collected groundwater samples from Masinloc, Zambales, Philippines. Fifty-four (54) water samples were collected in 250-mL sterile polyethylene containers by purposive sampling from selected groundwater sources in six (6) barangays of Masinloc. The samples were vacuum filtered through a 1.2-μm pore glass microfiber filter, cultured onto non-nutrient agar (NNA) lawned with Escherichia coli, and observed microscopically for amoebic growth for 14 days using light microscopy. Amoebic growth was observed in 11.1% (6/54) of water samples. DNAs from positive samples were extracted and were made to react with polymerase chain reaction using Acanthamoeba-specific JDP1 (5'-GGCCCAGATCGTTTACCGTGAA-3') and JDP2 (5'-TCTCACAAGCTGCTAGGGAGTCA-3') primers, and universal primer Euk A (5'-AACCTGGTTGATCCTGCCAGT-3') and Euk B (5'-TGATCCTTCTGCAGGTTCACCTAC-3'). The presence of Acanthamoeba genotypes T4, T7, and T11 was confirmed using molecular and phylogenetic analysis. Our results confirmed that groundwater sources from two of six sampling sites (33.3%) in Masinloc, Zambales, were contaminated with potentially pathogenic FLAs. Proper identification of risk factors that may cause contamination consequently leads to the implementation of programs that will prevent future infections.

Filter paper- and smartphone-based point-of-care tests for rapid and reliable detection of artificial food colorants

Herein, a robust instrument-free point-of-care tests (POCTs) strategy was proposed for rapid naked-eye detection of artificial food colorants (AFCs) using filter paper as a sampling and response device. Indicator papers were prepared by one-step polycondensation of silane coupling agents onto glass microfiber filter papers, then colorimetric cards with fine color mappings to AFCs concentration gradients were handily fabricated by AFCs extraction with indicator papers via electrostatic interaction and hydrophobic effect. The lowest concentration for AFCs visual detection was as low as 10−6 M and the whole POCTs process could be finished within 1 min. Furtherly, color information (RGB and gray-scale values) of AFCs-stained indicator papers and colorimetric cards from smartphone APP was used to reconstruct digitized colorimetry and reinforce its validity by mitigating the possible errors from subjective judgement on colors. Finally, such a dual-mode POCTs strategy was experimentally proved to be highly reliable for rapid visual detection of three AFCs (brilliant blue, Allura red, and sunset yellow) in real drinks by contrast with several instrumental methods like spectrophotometry, HPLC and MS. Due to its fine portability, speediness, low cost and user-friendliness, this strategy paves a promising way for AFCs-related food safety control.

Water Turbidity and Suspended Particulate Matter Concentration at Dredged Material Dumping Sites in the Southern Baltic.

Dredged material dumping is an activity that causes some of the greatest changes in coastal waters. It results in the need to regularly monitor the properties of seawater related to water quality. In this study, we present the first wide-ranging attempt to correlate seawater turbidity and suspended particulate matter (SPM) concentrations within dumping sites and adjacent waters on the basis of in situ measurements. In the years 2019–2020, we examined four dumping sites, namely Darłowo, Gdynia, Gdańsk, and DCT, located in Polish coastal waters of the Baltic Sea, in the course of four measurement campaigns conducted in the spring, summer, autumn, and winter. The measurements were conducted using a turbidity sensor to determine the turbidity, in formazin turbidity units (FTU), a spectrophotometer to determine the concentrations of nutrients (total phosphorus (P-tot), phosphate phosphorus (P-PO4−3), total nitrogen (N-tot), ammonium nitrogen (N-NH4+), and nitrate nitrogen (N-NO3−)), as well as glass microfiber filters to determine the concentrations of SPM. The analysis of the relationship between the turbidity and SPM within the dumping sites in comparison to reference points showed that the dumping sites are very complex waters and that the issue must be approached locally. The highest turbidity values were registered in the spring, and they correlated linearly with the SPM concentrations (R2 = 0.69). Moreover, we performed a statistical cluster analysis to illustrate the similarities between sampling points in the four dumpsites based on nutrient concentrations. We conclude that the influence of the dumping sites on the local bio-optical and chemical properties significantly exceeds their borders and spreads to the adjacent waters. Nutrient concentrations in many cases exceeded the legal policy limits.

Transport and evaporation of aqueous co-solvent solutions in thin porous media

We have studied the imbibition and drying of water/co-solvent mixtures in paper and glass microfiber filters. The experiments reveal a rich interplay of solution imbibition, solvent evaporation and solvent-mediated pore-fiber transport. After deposition, liquids occupy the micron-scale inter-fiber pores of a paper sheet. In thermodynamic equilibrium, polar liquids such as water and co-solvents reside in the nm-scale intra-fiber pores of the cellulose fibers. The timescales for attaining equilibrium prove to depend sensitively on the water content, such that co-solvents can be temporarily trapped in a non-equilibrium configuration. The combination of two experimental methods allows the determination of both the overall co-solvent content and an estimation of what fractions reside in the pores and in the fibers of a paper sheet. The results are relevant to understanding the behavior of solutions in paper and provide insight into the dynamics of aqueous inkjet printing inks.

Fluorescent sensor based on pyrroloquinoline quinone (PQQ)-glucose dehydrogenase for glucose detection with smartphone-adapted signal analysis.

A new nano-structured platform for fluorescent analysis using PQQ-dependent glucose dehydrogenase (PQQ-GDH) was developed, particularly using a smartphone for transduction and quantification of optical signals. The PQQ-GDH enzyme was immobilized on SiO2 nanoparticles deposited on glass microfiber filter paper, providing a high load of the biocatalytic enzyme. The platform was tested and optimized for glucose determination using a wild type of the PQQ-GDH enzyme. The analysis was based on the fluorescence generated by the reduced form of phenazine methosulfate produced stoichiometrically to the glucose concentration. The fluorescent signals were generated at separate analytical spots on the paper support under wavelength (365nm) UV excitation. The images of the analytical spots, dependent on the glucose concentration, were obtained using a photo camera of a standard smartphone. Then, the images were processed and quantified using software installed in a smartphone. The developed biocatalytic platform is the first step to assembling a large variety of biosensors using the same platform functionalized with artificial allosteric chimeric PQQ-dependent glucose dehydrogenase activated with different analytes. The future combination of the artificial enzymes, the presently developed analytical platform, and signal processing with a smartphone will lead to novel point-of-care and end-user biosensors applicableto virtually all possible analytes.