Glass Fiber Filters Research Articles

Assessment of the adverse effect of crop residue burning on respiratory health: a case study of Patiala, India

BackgroundCrop residue burning (CRB) is one of the top contributors to ambient air pollution (particulate matter 2·5 [PM2·5]) in north-western India. Despite the magnitude of the problems associated with high particulate amounts, there are few epidemiological data in India on the associated health effects of CRB, focusing on rural populations. The present study was conducted to quantify the effect of PM2·5 from CRB on the respiratory health of agricultural community in the Nabha block in Patiala, India. MethodsParticipants aged 10–60 years who were residents of six villages in the Nabha block in Patiala, India, who had resided in the area for at least 10 years and had self-reported as being in good health and non-pregnant women were enrolled in this cross-sectional study using purposive sampling. The participants were recruited from their residence, and all volunteered to participate in the study. The study population was surveyed for self-reported health symptoms and other exposure confounders. Lung function tests (LFTs) were done to examine forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF), both during CRB and non-CRB periods. 24-h continuous PM2·5 monitoring was done using the modified low-volume Combo Dust Samplers and particles were collected in glass fiber filters. The PM2·5 mass concentrations were analysed using the standard gravimetric method. Multiple regression models were used to quantify the association of PM2·5 from CRB on respiratory health after controlling for other exposure variables; namely, cooking fuel, ventilation, and distance from the road. FindingsA total of 3644 participants were enrolled from Oct 16 to 26, 2018, and March 7 to April 3, 2019 (the non-CRB periods), and from Oct 27 to Nov 20, 2018 and from Nov 3 to 13, 2019 (CRB periods). The present study showed significant associations between PM2·5 exposure and poor respiratory health with an increased prevalence of respiratory symptoms and lung function decrement among the study population. The older group (>40–60 years) reported more respiratory complaints during CRB than the younger groups (10–18 and >18–40 years), including coughs (OR 1·57; 95% CI 1·14–2·16), phlegm (1·69; 1·19–2·16), and itchiness of the eyes (3·44; 2·54–4·66). The study found a decrease in the results of LFTs with increasing PM2·5 across all age groups during CRB compared with the non-CRB period. The youngest group (10–18 years) had the highest reduction in lung capacity based on LFT variables. In men, FEV1 declined 16% in those aged 10–18 years, 9% in those aged older than 18 to 40 years, and 10% in those older than 40 to 60 years; and in women, it declined 26% in those aged 10–18 years, 12% in those older than 18 to 40 years, and 7% in those older than 40 to 60 years, during CRB (with a mean PM2·5 increase of 167 μg/m3). Similar declines were noted for the other (FVC and PEF) lung function variables. InterpretationThis study, which shows the adverse effects on health from CRB (increases in respiratory symptoms and poor lung function), highlights to need to accelerate policy interventions and engage farmers in discussions on CRB elimination. FundingCentral Pollution Control Board of India (B-33014/40/2018/AQM-EPC 9836).

Assessment of welding fume impacts in a confined workplace by two extraction patterns - a case study of small-scale manufacturing industries.

Welding fume exposure at work is recognized as a known concern for public health. This study aims to assess the welding fumes produced during welding using two different extraction patterns and to compare their influences. A thorough assessment of domestic arc welders in the erode district of India was done to assess their exposure to welding gases. The survey results chose the gas metal arc welding (GMAW) process for future investigation. The stainless-steel grade SS 316 L was used in this study. To weld 3-mm, 5-mm, and 6-mm-thick stainless-steel specimens, ER316 L filler wire and four shielding gas compositions were used. Two distinct, cost-effective welding hoods with a square duct section and a conical duct section were constructed to examine welding gases. The produced fume was collected on a 240mm glass fibre filter and re-weighted during welding. Gas flow rates of 5, 10, and 15 LPM were investigated, with current intensities of 150A, 200A, and 275A. A novel attempt has been made to compare fume formation rates (FFR) obtained using two extraction patterns. According to this investigation, weld fume hoods with conical duct sections extract more welding gases than square duct sections. The extraction rate using two extraction patterns was compared. Furthermore, the addition of CO2 to any shielding gas mixture results in a higher fume formation rate. The experimental FFR values were quite close to the American Welding Society (AWS) specifications. This finding also revealed that welders' socio-demographic characteristics, such as age, marital status, level of education, and work experience, influenced their awareness of occupational hazards and personal protection equipment (PPEs). As a result, there should be a strong emphasis on hazard identification education and strict enforcement of proper PPEs use among small-scale welders in and around the erode district to protect welders from a variety of hazards.

Occupational exposure and risk assessment for agricultural workers of thiamethoxam in vineyards

Dermal & inhalation exposure was examined and according to these results, risk assessment of agricultural workers to thiamethoxam was performed during pesticide mixing/loading and hand-held sprayer application (11 replicates, each of about 1000 L of spray suspension) in vineyards. For the whole body dosimetry (WBD), clothing (Outer and inner), gauze, and nitrile gloves were analyzed to determine dermal exposure using whole-body dosimetry exposure protocol. The inhalation exposure was measured using a glass fiber filter with an IOM sampler. Analytical method validation of exposure matrices was evaluated including the field recovery and breakthrough test. The dermal exposure amount during mixing/loading was 0.163 mg (0.0004% of the total mixed/loaded active ingredient [a.i.]), whereas there was no inhalation exposure. The gloves (0.154 mg, 94.5%) were the most exposed body parts followed by the chest and stomach (0.009 mg, 5.5%). During application, the dermal and inhalation exposure amounts were 32.3 mg (0.07% of the total applied a.i.) and 10.8 µg (2.4 × 10−6% of the total applied a.i), respectively. The shin (35.1%) had the highest exposure to pesticides, followed by the chest & stomach (15.6%) and pelvis (12.6%). In case of mixing/loading, the amounts of actual dermal exposure (ADE) and actual inhalation exposure (AIE) were 0.0 and 0.0 μg/day, while those of ADE and AIE were 4707.6 and 15.8 μg/day for application. In risk assessment of the two different scenarios, the risk index was much lower than 1 (mixing/loading:0.000, application:0.014), indicating that vineyard workers are at low risk of thiamethoxam exposure. To determine the validity of the risk assessment using WBD method, the urinary metabolite was analyzed. Comparison of biomonitoring data and WBD exposure data show a reliable correlation (r = 0.885, p = 0.0003), suggesting that these are suitable methods to estimate exposure.

Wood-Inspired Filter with a Lignin-Reinforced Nanocomposite Layer for Enhanced Oil/Water Separation and Selective Dye Removal

Nanocomposite filter membranes have attracted a great deal of attention in water purification. However, the weak interaction between nanomaterials and filter matrices severely reduces the stability and causes secondary pollution. Herein, inspired by the structure and function of natural wood, we report a simple strategy for fabricating a filter that uses alkaline lignin as a multifunctional modifier to tailor graphene oxide (GO) and bridge from GO to the surface of the glass fiber (GF). The obtained lignin-GO-modified GF filter was covered by a thin nanocomposite layer (∼2 μm) and exhibited hydrophilic and underwater oleophobic properties. It performed well in separating different oil-in-water emulsions (>92% for n-hexadecane, n-dodecane, and engine oil) under gravity and in selectively removing cationic dyes due to interception and adsorption via electrostatic effects and π–π interactions. Moreover, the filter had good stability and could be regenerated by washing without a significant loss of removal efficiency of n-dodecane-in-water emulsions during five consecutive cycles (1.86% per cycle). Therefore, this study shows that the wood-inspired filter membrane holds considerable promise for wastewater treatment, especially for oil/water separation and selective dye removal.

Determination of metallic nanoparticles in air filters by means single particle inductively coupled plasma mass spectrometry

Single particle inductively coupled plasma mass spectrometry (spICP-MS) has been explored for the determination of metallic nanoparticles (NPs) in air. Different extraction strategies (i.e., direct immersion, hard cap espresso, ultrasound-assisted and microwave-assisted extraction) and extracting solvents (i.e., citric acid, trisodium citrate, potassium nitrate, sodium nitrate, thiourea, disodium pyrophosphate and ammonium hydroxide) were investigated for platinum and gold NPs recovery from glass and microquartz fiber filters with a nominal size cut-off of 300 nm. Results show that metallic NPs are preserved and quantitatively extracted from the filter in 4 min inside an 800 W microwave oven by using 40 mL of a 2.0% w w−1 NH4OH solution. For the remaining extraction procedures, either incomplete recoveries or NPs degradation occur. As regards the influence of filter material, microquartz fiber affords better NPs capturing performance than glass fiber ones, enabling the quantification of NPs with diameters above 28 nm. This methodology has been successfully applied to determine PtNPs in filters from environmental monitoring stations and to gain insight into NPs transport through ICP-MS sample introduction system. Care should be taken during spICP-MS calibration since biased results might be obtained due to differences on NPs transport efficiency between standards and samples.

Comparative Evaluation of Common Materials as Passive Samplers of Environmental DNA.

Environmental DNA (eDNA) technology has revolutionized biomonitoring in recent years; however, eDNA collection from aquatic environments generally relies on the time-consuming and equipment-dependent process of water filtration. Passive eDNA sampling deploys sorbent materials to capture eDNA from water, circumventing many problems associated with active filtration; yet, very few candidate materials have been systematically evaluated for this purpose. Here, we evaluated the ability of 12 different types of common loose sorbents and filter membranes to capture eDNA in laboratory and field experiments compared with conventional water filtration. Glass fiber filters (GF) outperformed all other materials in laboratory experiments with respect to their quantitative capacity to recover amphibian eDNA, with the eDNA yield increasing linearly with submersion time up to 72 h. Furthermore, GF rapidly (within 0.5 h) captured the eDNA of up to 71% of the total fish species in a lake, in addition to detecting the entire fish community by 8 h, as assessed by metabarcoding analysis. Our results demonstrate that GF could passively capture aqueous eDNA with a similar or greater efficiency than conventional methods, thus paving the way for convenient, effective, and eco-friendly eDNA sampling in aquatic environments.

Solar photocatalytic degradation of carbaryl in water using TiO2-coated filters with different binders and effect of the operating conditions.

This research focused on degradation of carbaryl in water using TiO2-coated glass-fiber filter under sunlight irradiation. The coating substances were 0.3-2% w/v TiO2 mixed with 5 different binders, DURAMAX B1000, PEG molecular weight of 1000, 2000, 4000, and 6000, in a concentration of 0.3-2 wt% of TiO2. Optimum concentration of coating substance was investigated for the best degradation efficiency in terms of reaction kinetic rates. Sorption of carbaryl and zeta potential of coating substance were also studied.The results revealed that carbaryl sorptions on the coated filters were 2% or less. The optimum concentration of coating substance was 1% w/v TiO2 and 1 wt% PEG6000 with the kinetic rate constant of 0.022-0.025min-1. The point of zero charge of 1% w/v TiO2 + 1% wt% PEG6000 occurred at pH 7.5, while the pH of carbaryl solution was 7.3 ± 0.3. Thus, TiO2 was neutral, and repulsive force did not exist in this optimum coating. With the optimum TiO2 loading of 1-2g/L, 100% carbaryl degradation was obtained in 150min.

(Digital Presentation) Fabrication of Conductive Carbon Composite Films for Freestanding Lib Anodes Using Cellulose Nanofiber Binder

Fig.1 Cycle performance and Coulomb efficiency of graphite/CNT/CNF composite electrodes Introduction Currently, lithium-ion batteries (LIBs) have been the primary power source for electric vehicles and portable devices. LIBs consist of anodes (e.g. graphite), cathodes (e.g. LiCoO2: LCO), and electrolytes,[1] and are dis-/ charged as Li+ de-/ intercalate between the electrodes. Since LIBs require expensive fluorinated polymer as binders (e.g. poly (vinylidene fluoride): PVDF) and a volatile and toxic organic solvent such as N-methyl pyrrolidone (NMP), cheaper and easier-to-handle materials are necessary. Furthermore, the metal substrates (Cu, Al foil, etc.) as the current collectors are heavy and reduce the weight energy density of electrodes. Therefore, providing alternatives to the conventional components of LIB electrodes is a key challenge. Developing functional nanocomposites using sustainable natural resources is one of the most importance strategies.[2] Conductive thin films of cellulose nanofibers (CNFs) combined with carbon nanotubes (CNTs) have been reported as novel carbon composites.[3] Environmentally friendly and only carbonaceous electrodes without PVDF and organic solvents, and graphite are normally used for anodes. As an allotrope of graphite, CNTs have been approved to be a suitable anode material due to their unique structure (one-dimensional cylindrical tubule of graphite sheet), high conductivity (106 Sm-1 at 300 K), low density, high rigidity (Young’s modulus 1 TPa), and high tensile strength (up to 60 GPa).[4] In this study, the free-standing carbon composite anodes were successfully fabricated by using ultrasonication of CNF/ CNT or graphite mixture and vacuum filtering. Graphite slurry as the active material layer was dispersed in DI-water as the solvent containing CNF binder. This composite film has a dual-layer structure consisting of graphite/CNF active materials layer and CNT/CNF layer; here, the CNT/CNF layer with a thickness of about 10 μm is utilized as a current collector replacing the conventional metal substrate. These fabricated electrodes were evaluated by structural evaluation and dis-/ charge measurements. Experimental method CNF gel (2 wt%, Rheocrysta, DKS Co. Ltd.) and functionalized (carboxylic acid) multi-walled CNT (f-MWCNT, Sigma-Aldrich) were suspended in DI-water and sonicated for 2 h. Synthetic graphite was dispersed in DI-water with 5 wt% CNF and 10 wt% Carbon Black (CB) as a conductive material and sonicated for 30 min. Nanocomposite dual-layer films were formed by vacuum-filtering the dispersion using PVDF (pore size: 0.1 μm) membrane filters. These films were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), and Raman spectroscopy. The conductivity was measured by four probe method. The electrochemical properties of the free-standing electrode were measured using coin cells at room temperature. The coin cells were assembled in an argon-filled glovebox using Li as a counter electrode, glass fiber filter as a separator, and 1 M LiPF6 in a 1:1 (volume) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) as the electrolyte. Charge-discharge characteristics were recorded from 0.01 to 3 V at charging speeds of 0.1 – 2 C. The electrochemical impedance spectra (EIS) were measured in the frequency range from 100 mHz to 100 kHz with a potential perturbation at 5 mV. Results CNF combined with CNT constructs a robust conductive fibrous network, and CNT linked with graphite builds electronic conductive paths to improve the electronic conductivity. Specific capacities of the electrode were 44 mAhg-1 at 2 C and 272 mAhg-1 at 0.5 C, respectively (Fig.1). The discharge capacity of the first cycle was 363 mAhg-1 at 0.1 C. After 125 cycles, the discharge capacity was 255 mAhg-1 at 0.5 C. The ratio of the charge and discharge capacities (Coulombic efficiency) suggests that the charge-discharge behavior is stable in the cycle measurement, indicating that the irreversible capacity was small. Other information obtained by cyclic voltammetry (CV), and EIS measurement and further results will be shown in the presentation. In summary, we successfully fabricated the graphite/CNT/CNF composite film as environmentally friendly and lightweight anodes for the first time. The present results indicate that graphite/CNT/CNF composite film is a good candidate of flexible free-standing anodes. This research focused on CNFs as a promising alternative to conventional battery materials, and CNFs were successfully used to fabricate electrodes without using expensive PVDF binders and toxic organic solvents. Moreover, the gravimetric energy density was improved by replacing the conventional heavy Cu foil with a lightweight and thin composite film of CNT/CNF.

Light absorptance of algal films for photosynthetic rate determinations

A Reflectance Absorptance Transmittance (RAT) meter, developed for routine measurements of Abtλ nm on leaves, was used to measure absorptance of algal films mounted on glass fibre filter disks for use in PAM (Pulse Amplitude Modulation) fluorometry. Absorptance readings (Abtλ nm) are essential to quantitate the photosynthetic electron transport rate from PAM data and are also helpful if algal disks are used in an IRGA (InfraRed Gas Analyzer). Measurements were made on Synechococcus R-2 (Cyanophyceae), Acaryochloris marina (Chlorobacteria), Chlorella vulgaris (Chlorophyceae), Chaetoceros sp. (Bacillariophyceae) and Isochrysis sp. (Haptophyta) in blue (445 nm), green (525 nm) and red (625 nm) light. Plots of Abtλ vs. Chl a (mg Chl a m-2) or Chl d for Acaryochloris (mg Chl d m-2) of the algae followed exponential saturation curves (Abt%λ = Abt%λ, ∞ (1-e-k×Chl)) usually reaching asymptotes in the blue light used by blue-diode PAM machines. Synechococcus, Chlorella, Chaetoceros and Isochrysis Abt%445nm saturates ≈ 50-100 mg Chl a m-2 (Synechococcus: Abt%445 nm, max = 77.3±0.94, ±95% conf. limits, Chlorella: Abt%445 nm, max = 77.0±2.06, Chaetoceros: Abt%445 nm, max = 80.6±1.87; Isochrysis: 83.2±8.06 mg Chl a m-2); Acaryochloris above about 100 mg Chl d m-2. Asymptotic loading of cells was in general easily achieved in blue light in the case of Synechococcus, Chlorella and Acaryochloris but not in green, red or “white” light. It was difficult to achieve asymptotic loading for Chaetoceros and Isochrysis due to mucilaginous blockage of the filter disks.

Characterization, spatial distribution, and health risk assessment of polycyclic aromatic hydrocarbons and heavy metals bounded PM2.5 in urban air of Tabriz, Iran


 
 
 
 Introduction: Air and its invisible components play an influential part in the existence of living beings. The two factors of urbanization and industrialization of cities increase the concentration of various compounds in the air. This study has been designed to examine seasonal characterization, spatial distribution and health risk assessment of sixteen Polycyclic Aromatic Hydrocarbons (PAHs) and eleven heavy metals bounded PM2.5 at 16 sites in urban air of Tabriz, Iran.
 Materials and methods: Glass-fiber filters, peripheral pumps and PMI holder were used with a total 3 L/min flow rate for 24 h sampling Particulate Matter less than 2.5 μm (PM2.5) every 4 seasons at 16 sites from 20nd February to 20th December. Proper solvents are consumed for extraction purposes of these Materials. Inductively Coupled Plasma-Optical Emission Spectrometry (ICP- OES) and Gas Chromatography–Mass Spectrometry GC/MS devices used for analyzing purposes and the spatial distribution of PAHs and heavy metals bounded PM2.5 investigated by ArcGIS 10.3. Excess Lifetime Cancer Risk (ELCR) values and carcinogenicity risk were also calculated for children and adults in different exposure pathways.
 Results: The annual mean concentrations of PM2.5 were 41.17 μg/m3, ∑16 PAHs bounded-PM2.5 were much higher in autumn and winter (217.47 and 178.32 ng/m3) compared to summer and spring (162.61 and 131.89 ng/m3). The annual mean concentrations of heavy metals bounded-PM2.5 were 138.69 ng/m3. Dermal carcinogenicity risk of exposure with PAHs and ELCR values of heavy metals indicated high risk for adults and children in some stations.
 Conclusion: Considering the topographic location of the region, Industrial areas and the frequent presence of temperature inversion, such comprehensive researches are needed for control policies
 
 
 

Evaluation of fine particulate matter (PM2.5) concentration trends over heavily-industrialized metropolis of Ahvaz: Relationships to emissions and meteorological parameters

Introduction: Today, with the industrialization of societies, the expansion of urbanization and the increasing trend of population growth, sustainable livelihoods are severely polluted and unfortunately around the world, especially in developing countries, urban air quality is declining. This study is designed to determine the concentration of PM2.5 particles and the effect of meteorological parameters in 14 selected points in the metropolis of Ahvaz. Materials and methods: The sampling of Particulate Matter less than 2.5 µm (PM2.5) was in four seasons (winter, spring, summer and autumn). Sampling was performed using the Environmental Protection Agency, method TO-13A (EPA/TO-13A) guideline. Particle samples were collected on a fiberglass filter with a pore size of 1 µm and diameter of 37 mm. Information about meteorological parameters was also recorded by PHB-318. Finally, the obtained data were analyzed by SPSS and R. Results: The results showed that the concentration of PM2.5 particles in the metropolis of Ahvaz during the study period is 14 times higher than the value of the guidelines of the World Health Organization (WHO). Also, temperature had a negative relationship and relative humidity and pressure had a direct and positive relationship with concentration of PM2.5 particle. It was found that Zargan, Padadshahr 1and 2, Saadi and 17 Shahrivar stations are the most polluted points compared to PM2.5 particles. Conclusion: Planning appropriate strategies of air pollution control to reduce is important and necessary.

NeuroTorp, a lateral flow test based on toxin-receptor affinity for in-situ early detection of cyclic imine toxins

The emergent cyclic imine toxins produced by marine dinoflagellates are potent antagonists of nicotinic acetylcholine receptors. Shellfish accumulate cyclic imine toxins following filter-feeding on toxic dinoflagellates vectoring them to humans. Herein is presented a lateral flow test for the detection of cyclic imine toxins based on three new concepts for test strips: i) the immobilization of lipoprotein vesicles in the test-line, ii) the high affinity of neurotoxins for their receptor targets and iii) the use of high porosity glass fiber filter membranes as support for the fabrication of the lateral flow test NeuroTorp (WO2017108115). Purified electrocyte membrane vesicles from Torpedo marmorata were used as a source of receptor and were immobilized in the test-line. Biotin-α-bungarotoxin was used as toxin tracer for the NeuroTorp LFT given its high affinity for nicotinic acetylcholine receptors while neutravidin nanogold particle conjugates enable its visual detection. Herein is reported for the first time the use of GF/C glass fiber membranes as the stationary phase for a lateral flow test. The GF/C filter ensures both: the immobilization of a complex lipoprotein in the test-line and the capillary migration of the mobile phase. Scanning electron microscopy studies shed light into the mechanism by which Torpedo-electrocyte membranes vesicles are immobilized in the GF/C glass microfiber. The electrocyte membrane vesicles anchor in neighboring microfibers randomly disposed in the same plane of the GF/C filter forming stable microfilm structures ensuring the functionality of nicotinic acetylcholine receptors. NeuroTorp is a ready-to-use low-cost early warning device for rapid detection of cyclic imine toxins in shellfish by end-users.

On the historic exposure levels of Elemental Carbon from vehicle diesel exhaust based on “diesel smoke” concentrations

Air pollution by diesel traffic became a concern in the UK in the 1950s. Exposure levels were assessed via probing the light absorption of filter samples, which was translated to a mass concentration of “diesel smoke” (DS), based on the results of a measurements in the exhaust of a test diesel engine. We convert these DS values to concentrations of Elemental Carbon (EC), the current proxy for diesel exhaust. In a recent study in the literature and an earlier own investigation a high similarity (R2 = 0.97) was found of the light absorption by aerosol collected in parallel on glass and quartz fibre filters and probed by smoke-stain reflectometers similar to those used historically. For samples on quartz fibre filters the relation between light absorption and EC was taken from recent studies. The shape of the absorption/EC curve is highly similar to the absorption/DS curve, with an equivalency factor of 1.6 ± 20% between DS and EC concentration (expressed according to the EUSAAR2-TOT method). Converted EC concentrations for workday average 24-hr and morning rush hour samples were around 75 and 150 μg m−3 at the kerbside of the busy London A1 ring-road in 1960. In 1961–1962 the average weekday daytime EC concentration at a traffic island in inner city Fleet Street was 200–250 μg m−3. Only 45 m into a side-street the concentration was an order of magnitude less. At the end of the 1990-ies EC concentrations at the nearby Marylebone Road were around 9 μg m−3, dropping to 3 μg m−3 in recent years. In addition, we found the correct factor to convert light absorption to EC mass concentration of samples obtained in the FH62 beta gauge monitors used in Germany in compliance measurements for the national “soot law” preceeding the EU PM10 regulation of 1997.

Fast screening of saxitoxin, neosaxitoxin, and decarbamoyl analogues in fresh and brackish surface waters by on-line enrichment coupled to HILIC-HRMS.

The proliferation of harmful cyanobacterial algal blooms is of concern due to the associated release of toxins affecting ecosystems and human health. The paralytic shellfish poison saxitoxin (STX) is a small polar alkaloid that can occur in inland and marine aquatic environments. Here, we optimized a fast and sensitive analytical method for the determination of STX, neosaxitoxin (NeoSTX), and their decarbamoyl analogues in surface waters. The method involves a simple filtration, addition of isotope-labelled internal standard (ILIS), and analysis by on-line solid-phase extraction coupled to hydrophilic interaction liquid chromatography high-resolution mass spectrometry (on-line SPE-HILIC-HRMS). Except glass fiber filters, other tested materials (e.g., nylon, nitrocellulose) provided suitable filtration performance. Time-dependent adsorptive losses occurred during the LC-MS batch sequence if glass autosampler vials were used, while no such effect was observed for polypropylene autosampler vials. Matrix effects were evaluated for 4 different quantification scenarios, including external vs. internal curves and neat reagent water vs. matrix-matched curves. Matrix-matched calibration with ILIS correction (NeoSTX-15N7) provided the best performance overall. The analytical method was validated in freshwater lake water and estuarine brackish water (30‰ salinity), with suitable determination coefficients (R2>0.9975), matrix spike accuracy (90-107%), and intraday/interday precision (RSD of 0.61-16%). Method limits of detection (LOD in lake water: 0.72-3.9ng/L) are also improved over most of the recent literature. The method was applied to a set of 302 surface water samples collected in Canada, France, and the United Kingdom, and positive detections were reported for STX (max: 98ng/L), decarbamoyl-STX (max: 15ng/L), and NeoSTX (max: 87ng/L).

Multi-mechanism theory of aerosol capture by fibrous filters, including fiber diameter/orientation dispersity and particle morphology effects. Preliminary tests vs. data for mobility-selected submicron particles

In Paper I (Sep. Purif. Technol. 257 (2021) 117676) we showed that a semi-analytic, multi-mechanism expression for the single-fiber capture fraction, ηcap,SF, (derived using asymptotically valid approximations: Ref<0.4, Pef≫1, R≪1, R⋅Pef1/3 arbitrary and Stkp≤Stkpcrit), facilitates a deterministic-, pseudo-continuum aerosol population-balance (PB-) approach to predicting fibrous filter performance. There we explicitly considered “deep” (Lf/df,g≫1), low solidity idealized fibrous filters (FFs) challenged by polydispersed aerosols—especially single-mode log-normal (LN) ASDs of modest spread captured by a spatially uniform array of fibers of a single diameter in crossflow. However, realistic fibrous filter media often possess a LN distribution of fiber diameters, as well as a near-Gaussian orientation distribution narrowly spread about normal incidence (θ=π/2). Moreover, even if this were not so, there would be meso-scale departures from a uniform average fiber solid fraction. We show here that our tractable aerosol PBE-approach to idealized FF performance (Paper I) can be generalized to incorporate these particular structural features of commercially available fibrous filter media. But, to clarify whether these generalizations are likely to be useful, if not fully sufficient, for practical circumstances, it is also necessary to compare such methods/predictions against selected sets of well-defined experimental results. We initiate this program here, having chosen the recent experiments of Kang et al. (2019) carried out using a commercially available fiberglass filter with Lf/df,g≃300, mean solid fraction of 0.039, and df,g=2.5μm, successively challenged by mobility-selected KCl(s) particles (with diameters between ca. 20 and 600nm) at the carrier gas velocities of 15 and 10 cm/s—capture conditions dominated by the transport mechanism of Brownian diffusion and convection, with “interception” (associated with non-negligible dp/df) becoming important above ca. dp=100nm. We conclude from these data that the effective interception diameter, dp,icpt,eff, of the particles studied is systematically larger than their stated mobility diameters—a situation which will deserve further attention in future studies. Encouraged by these preliminary but instructive comparisons, we expect that, for many current and future design purposes, our present class of semi-analytic/non-stochastic/multi-mechanism methods will provide a welcome complement, if not alternative, to much more computationally-intensive simulation methods for realistic fibrous media that have been described and implemented in the recent aerosol filtration literature. The consequences of including these structural features of fibrous filters in the presence of aerosol size- and shape polydispersity will be the subject of future studies, based on the generalized Population Balance Equation developed/proposed in Section 3.3.

Effect of β-Estradiol on Mono- and Mixed-Species Biofilms of Human Commensal Bacteria Lactobacillus paracasei AK508 and Micrococcus luteus C01 on Different Model Surfaces

The impact of steroid hormones, and particularly estradiol, on human microbiota could be recognized as a substantial part of human-microbiota interactions. However, an area that remains poorly investigated is that of the skin and vaginal microbial communities and biofilms, which contain non-pathogenic bacteria of phyla Firmicutes and Actinobacteria, especially probiotic bacteria of the genus Lactobacillus and the widespread, safe skin genus, Micrococcus. Experiments with Lactobacillus paracasei AK508 and Micrococcus luteus C01 biofilms on PTFE cubes showed dose-dependent effects of estradiol at concentrations of 0.22 nM and 22 nM. The hormone mostly inhibits L. paracasei growth and stimulates M. luteus. The presented studies of colony-forming unit (CFU) amountsand cell aggregation in biofilms on glass fiber filters showed the same general tendencies. Estradiol generally increased the aggregation of cells in monospecies communities and potentially changed the synthesis of antibacterial metabolites in L. paracasei. The balance between two bacteria in mixed-species biofilms depended on the initial adhesion stage, and when this stage was reduced, micrococci were more resistant to the antagonistic action of L. paracasei. Moreover, in mixed-species biofilms, the effect of estradiol on lactobacilli altered from inhibition to stimulation, potentially due to the presence of M. luteus. At the same time, ethanol as a solvent for estradiol at the concentration 0.6% acted mostly as an antagonist of the hormone and had an opposite effect on bacteria; nevertheless, the overlapping of ethanol and estradiol effects was shown to be minimal. The data obtained prove the complexity of microbial interactions and the regulatory effect of estradiol on commensal bacteria biofilms.

Compact Ag nanoparticles anchored on the surface of glass fiber filter paper for SERS applications

Compact Ag nanoparticles anchored on the surface of glass fiber filter paper for SERS applications

Measuring the ambient air pollutants in Garmsar industrial district

Introduction: Nowadays, air pollution is one of the main health and environmental problems in developing cities, which is a result of the increasing use of fossil fuels, heat generators and the activities of industrial districts and industries.&#x0D; Materials and methods: In order to conduct this descriptive cross-sectional study, the sampling site of Garmsar industrial district in Semnan province was selected. For air sampling, a large sample sampling pump, a cyclone holder filter and a fiberglass filter were used. The air sampling operation lasted from June to September, 2021. Sampling was performed in three days a week at a speed of 0.5 m/s. Therefore, 15 samples were taken per month and 60 samples were taken in each study period to measure each group of particles.&#x0D; Results: Based on the results of the evaluation of air pollutants, among the measured pollutants, only the amount of suspended particles and sulfur dioxide in some sampling days is higher than the maximum allowable concentration of the standard ambient air. The Air Quality Index (AQI) for Particulate Matter less than 10 µm (PM10) in August exceeded the allowable level (100), and for Sulfur dioxide (SO2) in September.&#x0D; Conclusion: Since the concentration of particulate matter and sulfur dioxide and consequently the amount of AQI in some sampling days is higher than the maximum allowable concentration of ambient air standard, continuous monitoring of emission sources, determination and control of emission sources, and creating local and industrial guidelines in this area is essential.&#x0D;

Development of a cost-effective laser diode-induced fluorescence detection instrument for cyanide detection.

Cyanide is highly toxic to humans and the environment. It is very important to develop an on-site system for the quantitative analysis of cyanide with high sensitivity and reliability. In this study, we developed a cyanide detection system based on the reaction of vaporized cyanide on a glass-fiber filter soaked in a mixture of naphthalene-2,3-dicarboxaldehyde (NDA)-taurine-borate solution. Although the reaction product was stable for at least 3 days at room temperature, the reaction product on the strip was quickly quenched within a few minutes by direct irradiation with 405nm light. To overcome this problem, we fabricated a simple device designed to detect the fluorescence intensity immediately after inserting a reaction strip into the device. The linearity of the calibration was obtained over a range of 1-100µM of cyanide with good repeatability. The device is cost-effective (~ $300) and powered by batteries; therefore, it is suitable for the on-site determination of cyanide in crude samples.

Field comparison of fugitive tailings dust sampling and monitoring methods

This study compares select dust sampling apparatuses and monitoring methods by investigating fugitive tailings dust transport and deposition at an abandoned Zn-Pb-Cu mine located in eastern, Canada. The sampling apparatuses and monitoring methods are compared in terms of capturing seasonal trends and spatial extent, as well as the ability to evaluate impacts to aquatic ecosystems. Methods evaluated include satellite imagery, lichen tissue analysis, passive dry deposition collectors (Pas-DDs) with two different configurations, dust deposition gauges (DDGs) and a high volume total suspended particulate (Hi-Vol TSP) sampler. All methods utilized demonstrated benefits and challenges in relation to seasonal sampling and determining spatial extent of dust deposition. Results indicate that the polyurethane foam disk configuration of the Pas-DD sampler efficiently accumulates dust in comparison to the glass fiber filter configuration and DDGs which both likely underestimate dust deposition. Lichen and satellite imagery were shown to be effective tools for identifying areas of interest and extent of contamination. At the study site, it was observed that dust deposition was highest in the winter months and lowest in the summer months, likely due to increased erosion in winter weather conditions (higher wind speeds and/or freeze drying effect).