Μm In Size Research Articles

Are native microalgae consortia able to remove microplastics from wastewater effluents?

Wastewater Treatment Plants (WWTPs) are potential sources of microplastics (MPs) in the aquatic environment. This study aimed to investigate the potential of wastewater-native microalgae consortia to remove MPs from the effluent of two different types of WWTPs as a dual-purpose solution for MPs mitigation and biomass production. For that purpose, the occurrence of MPs from two types of WWTP effluents was analysed over one year. MPs were characterized in terms of morphology (microbead, foam, granule, irregular, filament and film), colour and size. The wastewater characterisation was followed by the removal of MP loads, using native microalgae consortia, pre-adapted to the wastewater effluent. Microalgae consortia evolved naturally through four mitigation assays, adapted to seasonal conditions, such as temperature, photoperiod, and wastewater composition. MPs were present in all the effluent samples, ranging from 52 to 233 MP L−1. The characterisation of MPs indicated a predominance of white and transparent particles, with irregular and filament shapes, mainly under 500 μm in size. The μFTIR analysis revealed that 43% of the selected particles were plastic, with a prevalence of polypropylene (PP) (34%) and polyethylene terephthalate (PET) (30 %). In the mitigation experiments, substantial biomass production was achieved (maximum of 2.6 g L−1 (d.w.)), with successful removal of MPs, ranging from 31 ± 25% to 82 ± 13%. These results show that microalgae growth in wastewater effluents efficiently promotes the removal of MPs, reducing this source of contamination in the aquatic environment, while generating valuable biomass. Additionally, the strategy employed, requires minimal control of culture conditions, simplifying the integration of these systems in real-world WWTP facilities for improved wastewater management.

Leaf Spot caused by Alternaria tenuissima on Rhamnella franguloides in China.

The small tree species Rhamnella franguloides, belonging to the genus Rhamnella in the tribe Rhamneae Hook. f. of Rhamnaceae (Hauenschild et al. 2016), is an important medicinal plant commonly used for making tea in China. In August 2023, leaf spot symptoms were observed on R. franguloides in Shangyao county, Yantai, Shandong, China, with a disease incidence of 45-65%. Initially appearing as small dark brown spots on the tip lesions, they later expanded and merged into irregular-shaped brown necrotic lesions with yellowish halos. To isolate pathogen, 20 symptomatic tissue fragments (5 × 5 mm) from ten sampling randomly plants were surface sterilized, placed on potato dextrose agar (PDA) plates, and incubated at 25°C in darkness for 3 days to obtain colonies.10 purified isolates with similar morphological characteristics were obtained by single-spore isolation from the colonies. The representative isolate MR13 was chosen for morphological and molecular analysis. The colonies On PDA medium initially appear as a circular yellow-brown ring with white round margins, ultimately turning into olive green with fluffy aerial hyphae. The conidiophores displayed brown pigmentation, solitary or branched, producing abundant short chains of conidia. The conidia were typically obclavate to obpyriform or ellipsoid in shape, 22.5-64.5 × 12.5-23.6μm in size, with a short conical beak at the apex, zero to three longitudinal septa and one to five transverse septa. Based on cultural and morphological characteristics, the fungus was identified as Alternaria spp (Simmons 2007). Due to morphological traits, five genes (the internal transcribed spacer [ITS], actin [ACT], plasma membrane ATPase [ATP], Alternaria major allergen [Alt a1] and histone 3 [H3]) form MR13 were amplified using primer pairs ITSI / ITS4, ACTDF1/R1, ATPDF1 / ATPDRI, Alt-for / Alt-rev, and H3-1a/1b, respectively (Hong et al. 2005; Lawrence et al. 2013; Lousie and Donaldson 1995). BLASTn analysis failed to confirm the identification of MR13 species based on ITS, ACT, ATP and Alt a1(ITS, OR668512; ACT, OR676918; ATP, OR676917; Alt a1, OR676919). The phylogenetic tree showed that it was closely related to Alternaria alternate, A. tenuissima, and A. destruens. The H3 sequence (OR676920) exhibited 100% similarity to A. tenuissima (OR485421). The phylogenetic tree constructed solely with H3 further confirmed MR13 as A. tenuissima. Pathogenicity tests were conducted by introducing the fungus onto healthy R. franguloides leaves in the field. Fifty leaves (five per plant) were treated with a 20ml suspension containing around 1x10^4 spores/ml, while an equal number of control samples were sprayed with distilled water. Transparent plastic bags were used to cover the treated leaves for 48 hours and maintain humidity. After fourteen days of inoculation, consistent leaf spotting symptoms were observed. In contrast, the control leaves showed no sign of infection. The fungal pathogen was successfully reisolated and identified as A. tenuissima through morphological and sequence analysis, fulfilling Koch's postulates. To our knowledge, this is the first report of A. tenuissima causing leaf spot disease on R. franguloides in China. Identifying the disease's causal agent is crucial for developing effective management strategies.

347 Aerodynamic Size Distribution of SARS-CoV-2 Aerosol Shedding

OBJECTIVES/GOALS: We designed the Biocascade Exhaled Breath Sampler (BEBS) to characterize viral aerosol shedding among individuals with influenza and other respiratory virus infections. We first aimed to test the BEBS on volunteer COVID-19 cases and report the aerodynamic size distribution of exhaled breath aerosol particles carrying SARS-CoV-2 RNA. METHODS/STUDY POPULATION: From June 15 through December 15, 2022, we recruited 27 PCR-confirmed COVID-19 cases from a college campus and the surrounding community to provide 30-minute breath samples into a well-validated Gesundheit-II (G-II) exhaled breath aerosol sampler. Among these individuals, 17 provided an additional exhaled breath sample into the newly designed BEBS. We quantified samples for viral RNA using reverse transcription digital polymerase chain reaction (RT-dPCR) and determined the viral RNA copies collected within two aerosol size fractions (≤5 µm and >5 µm in diameter) from the G-II, and four aerosol size fractions (<1.15 µm, 1.15–3.2 µm, 3.3–8.2 µm, and >8.2 µm) from the BEBS. RESULTS/ANTICIPATED RESULTS: Individuals with a SARS-CoV-2 Omicron BA.4 or BA.5 infection shed virus in aerosols at an average rate of 7.5x103 RNA copies per 30-minute G-II sample, with 78% of the total RNA in aerosols ≤5 µm in diameter. Among the BEBS samples, 10% of the total viral RNA was detected in aerosols <1.15 µm, 43% in 1.15–3.2 µm, 37% in 3.3–8.2 µm, and 10% in the >8.2 µm size fraction. Based on viral RNA loads, our results indicate that exhaled aerosols ≤3.2 µm contribute the majority of SARS-CoV-2 inhalation exposure. DISCUSSION/SIGNIFICANCE: Our data provide additional evidence that respirable aerosols contribute to the spread of SARS-CoV-2. Thus, our data suggest that mitigation measures designed to reduce infectious aerosol inhalation, such as ventilation and the use of air cleaners and respirators, are needed to control the spread.

Unveiling high concentrations of small microplastics (11–500 μm) in surface water samples from the southern Weddell Sea off Antarctica

Recent studies have highlighted the prevalence of microplastic (MP) pollution in the global marine environment and these pollutants have been found to contaminate even remote regions, including the Southern Ocean south of the polar front. Previous studies in this region have mostly focused on MPs larger than 300 μm, potentially underestimating the extent of MP pollution. This study is the first to investigate MPs in marine surface waters south of the polar front, with a focus on small MPs 500–11 μm in size. Seventeen surface water samples were collected in the southern Weddell Sea using an in-house-designed sampling system. The analysis of the entire sample using micro-Fourier transform infrared spectroscopy (μFTIR) with focal plane array (FPA) detection revealed the presence of MPs in all samples, with the vast majority of the MPs detected being smaller than 300 μm (98.3 %). The mean concentration reached 43.5 (± 83.8) MPs m−3, with a wide range from 0.5 to 267.2 MPs m−3. The samples with the highest concentrations differed from the other samples in that they were collected north of the continental slope and the Antarctic Slope Current. Sea ice conditions possibly also influenced these varying concentrations. This study reports high concentrations of MPs compared to other studies in the region. It emphasizes the need to analyze small MPs, down to a size of 11 μm or even smaller, in the Antarctic Treaty Area to gain a more comprehensive understanding of MP pollution and its potential ecological impacts.

First report of Lasiodiplodia pseudotheobromae causing soft rot of plum in China.

Plum (Prunus salicina) is one of the most important fruit tree species worldwide (Valderrama-Soto et al. 2021). In June 2023, the postharvest soft rot symptoms were observed on plum fruits in several fruit markets of Guiyang city, Guizhou province, China. The disease incidence in these markets ranged from 20 to 25% with 70% disease severity. Plum fruits showed rotting, which was characterized by water soaked fruit tissue, softening and presence of whitish mycelia four days post inoculation. In severe conditions, whole fruits become rotted and were covered with white fungal mycelia. Small sections (5 × 3 mm) from 6 diseased plum fruits were surface sterilized by using 75% ethanol for 30 s followed by 0.1% mercuric chloride solution for 5 min, rinsed three times with ddH2O, and then transferred onto potato dextrose agar (PDA) and incubated at 25 ± 2°C for three days. Three pure cultures (GUCC23-0001 to GUCC23-0003) were obtained by transferring a single hyphal tip to new PDA plates. Colonies of these isolates were grayish-white initially, gradually turning to whitish brown with fluffy aerial mycelia and uneven edges and finally turned to a dark gray colony after five days of inoculation. The pseudoparaphyses were hyaline, cylindrical, aseptate, and rounded at apex. Conidia were ellipsoidal, hyaline, unicellular, and 24.2 to 28.6 × 12.3 to 15.5 µm in size (n = 30) (Fig. S1), which were similar to the morphology of Lasiodiplodia pseudotheobromae (Alves et al. 2008). Furthermore, fungal DNA was extracted from fresh mycelia of PDA after seven days by using fungus genomic DNA extraction kit (Biomiga, USA). Partial DNA sequences from four loci including internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1), beta-tubulin (tub2), and polymerase II second largest subunit (rpb2) were amplified with ITS1 and ITS4 (White et al. 1990), EF1-688F and EF1-1251R (Alves et al. 2008), Bt2a and Bt2b (Glass and Donaldson 1995), and RPB2-LasF and RPB2-LasR, respectively (Cruywagen et al. 2017). GenBank accession numbers are OR361680, OR361681, OR361682 for ITS, OR423394, OR423395, OR423396 for tef1, OR423397, OR423398, OR423399 for tub2, and OR423391, OR423392, OR423393 for rpb2, and gene sequencing showed 99.6 to 100% identity with ex-type strain of L. pseudotheobromae (CBS 116459). Phylogenetic analysis also placed our isolates in a highly supported clade with the reference isolate of L. pseudotheobromae (Fig. S2). Another experiment was designed to confirm the pathogenicity test for additional confirmation. Five mm mycelial plugs of L. pseudotheobromae from a three day old culture on PDA were placed on five surface-sterilized and non-wounded plum fruits for 12 hours and incubated at 25°C ± 2°C for four days. Sterilized fungus free PDA plugs were used as a negative control. Mycelial plugs were removed after 12 hours following which whole fruits were incubated in plastic boxes at 25°C ± 2°C. The experiment was repeated twice. The pathogenicity was evaluated under control conditions in laboratory (relative humidity, 70 ± 5% and temperature 25 ± 5˚C). Plum fruits showed rotting, which was characterized by water soaked fruit tissue, softening and presence of whitish mycelia four days post inoculation. These symptoms and signs were similar to the initially observed symptoms on plums in the markets. No disease symptoms were observed on the control fruits. The re-isolated fungus obtained from inoculated plum fruits was very similar to those isolated from diseased samples in morphology, fulfilling Koch's postulates. To the best of our knowledge, this is the first report of L. pseudotheobromae causing postharvest fruit rot of plum in China. In 2022, the total planting area of plum was 1946.5 thousand hectares, which produces approximately 6626300 tons of plum (Food and Agriculture Organization of the United Nations, 2022). Based on the disease incidence and severity reported in the current study, soft rot of plum may be responsible for nearly 35% of yield losses under severe. Therefore, our study laid a theoretical foundation for the prevention and control of this post-harvest disease of plum.

Multi-layer solid-state ultrasonic additive manufacturing of aluminum/copper: local properties and texture

Ultrasonic additive manufacturing (UAM) is an advanced joining technique that utilizes ultrasonic vibrations to bond layers of metal foil together. UAM offers several benefits over traditional manufacturing methods, including enhanced design flexibility and reduced material waste, and its potential applications in various industries such as aerospace, automotive, and biomedical engineering are being actively explored. The study employs a nanoindentation apparatus to investigate the effect of the UAM process on the local mechanical properties of the bonded interface, along with changes in microstructure, which were investigated using scanning electron microscopy and electron back-scattered diffraction. The results revealed a significant correlation between material hardness and local plasticity. EBSD has revealed that the grain size distribution of Al far from the interface contains 57% of the grains less than 3 µm in size, while at the interface this number rises to approximately 78%, indicating that the average grain size decreases as it approaches the interface. This result is consistent with nanoindentation results that demonstrated a gradual change in the hardness of Al foil far from the interface to close to the interface (the maximum penetration depth near the interface was 500 nm less than far from the interface). Both EBSD and nanoindentation disclose the effect of work hardening close to the interface, which is related to dislocation accumulation with a density of 8.6×10-10cm-2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$8.6\ imes {10}^{-10} {{\ ext{cm}}}^{-2}$$\\end{document} beneath the interface. The consistency of hardness and Young’s modulus with the pole figures and microscopic images demonstrated that plasticity flow and fine grain distribution would only occur in the vicinity of the interface in the softer metal region. Although the harder metal did not exhibit plasticity or recrystallization, the hardness, and Young’s modulus map indicated the formation of a layer of small grains close to the interface on the aluminum side owing to strain hardening and dynamic recrystallization.

Microplastic concentrations and risk assessment in water, sediment and invertebrates from Simon's Town, South Africa

Plastic pollution is an ever-increasing threat globally and poor waste management in South Africa has caused an increase in plastic leakage into the environment. Plastic waste in the environment are categorized according to size and plastic particles smaller than 5 mm in size are regarded as microplastics (MPs), and little to no research has been done on MPs pollution within the marine coastal environment and rocky shores in South Africa. Sampling was done in February 2020 at a rocky shore within Simon's Town Marina, Cape Town. MPs were extracted from collected water (n = 5), sediment (n = 5) and biota (n ≤ 30) samples. The extracted MPs were further classified based on shape, colour, size and an attenuated total reflectance Fourier-transform infrared (ATR-FTIR) instrument was utilized for polymer type identification The risks posed by MPs because of concentration at which they occurred and chemical composition were assessed in all the sample types. As expected, MPs were higher in sediment (38 ± 2 MP/kg) than in water (0.37 ± 0.06 MP/L) as the area has low water energy, allowing MP particles to settle within the sediment. Filter-feeding organisms had the lowest average MP particle concentrations (0.28 ± 0.04 MP/g) but displayed the highest variation of MP particle colours due to the non-selective feeding strategy, where other feeding strategies ingested mostly black/grey particles. The dominant MP size was between 100 μm and 500 μm in size for all samples combined, with the most abundant MP polymer type being nylon (27.27 %), polyethylene terephthalate (PET) (18.18 %) and natural MP particles such as cotton (18.18 %). The risk assessment indicated that polymer type poses a greater risk of MP pollution than MP concentrations.

Solubility Enhancement of Poorly Water-Soluble Aceclofenac by Amalgamation Micronization and Solid Dispersion Techniques

Aceclofenac is a poorly aqueous soluble Biopharmaceutical Classification System (BCS) class II drug that has bioavailability problems after oral administration due to low aqueous solubility. There are numerous solubility modification approaches and they also have process limitations. Hence, the present research work aims to use two different solubility enhancement techniques (Micronization with Solid dispersion) simultaneously to counter individual limitations of techniques. The micronization technique increases the solubility of pure aceclofenac through increasing particle surface area, but it produces charged micronized material, leading to segregation and clumping of micronized material. Hence, micronized material handling during dosage form manufacturing is quite difficult. In the present research work, aceclofenac material is micronized by air jet mill to produce materials of below 25 μm size ranges. This micronized aceclofenac material is further encapsulated in a solid dispersion technique to produce amorphous aceclofenac materials. Solid dispersion of micronized aceclofenac was prepared by various techniques like physical kneading, solvent evaporation, melting and a combination thereof using different polymers (Polyox 301, HPMC, cetostearyl alcohol and glyceryl behenate). The prepared solid dispersion formulation (SD-31, SD-22, SD-23 and SD-30) exhibited an increase in the dissolution of aceclofenac as compared to pure aceclofenac. Various characterization techniques (Differential scanning calorimetry (DSC), X-ray Diffraction (XRD) and scanning electron microscope (SEM)) also reveal that aceclofenac crystallinity is significantly minimized in Solid dispersion formulation of SD-31, SD-22, SD-23 and SD-30. This selected solid dispersion (SD-31 and SD-22) also exhibited good stability (Photostability and stability at 40°C/75% RH after 3 months).

Exploring correlations between microplastics, microorganisms, and water quality in an urban drinking water source

The microplastic pollution in freshwater system is gradually becoming more severe, which has led to increasing attention on the distribution and potential harmful effects of microplastics. Moreover, microplastics may have an impact on river ecology and pose risks to ecosystems. Therefore, it is important to reveal this process. This study aimed to explore correlations between microplastics and free-living microorganisms in an urban drinking water source of Xiangjiang River by using multivariate statistical analysis. The results indicated that the abundance of microplastics (size 50 μm to 5 mm) in surface water and sediments ranged from 0.72 to 18.6 (mean ± SD: 7.32 ± 2.36) items L−1 and 26.3–302 (150 ± 75.6) items kg−1 dry weight (dw), respectively, suggesting potential microplastic pollution despite the protected status as a drinking water source. Higher microplastic abundances were observed in urban areas and the downstream of wastewater plants, with mostly granular shape, transparent and black color as well as 50–100 μm in size. The multivariate statistical analysis presented that the abundance of microplastics is not significantly correlated with water indicators, due to the complexity of the abundance data. The water indicators showed an obvious correlation with microplastics in colors of transparent and black, and smaller sizes of 50–100 μm. This is also true for microplastics and microorganisms in water and sediment. Proteobacteria was the main prokaryote in water and sediments, being positively correlated with 50–100 μm microplastics; while Chloroplastida was the dominated eukaryotes, presenting a weak correlation with smaller-size microplastics. Overall, when considering the properties of microplastics such as shape, color and size, the potential correlations with water indicators and microorganisms were more evident than abundance. This study provides new insights into the multivariate statistical analysis, explaining the potential correlations among microplastic properties, microorganisms and environmental factors in a river system.

Abstract 6782: 3D-EXpress - an ex vivo platform using viably cryopreserved tumoroids for rapid assessment of targeted therapeutic outcomes

Abstract Background: it has been a significant challenge to select, combine, and sequence the multiple FDA-approved IO therapies and pharmaceutical agents, highlighting the need to develop a precision oncology platform to explore novel combination treatments. 3D-EXpress is a unique ex vivo therapeutics testing platform using a biorepository of fresh patient tumoroids that were never dissociated, propagated, or reassembled to retain an intact microenvironment. Therefore, these specimens provide an excellent ex vivo platform to investigate the efficacy of therapeutics targeting the tumor microenvironment. Here, we employed the 3D-EXpress platform to compare the efficacy of different therapeutic modalities targeting tumor antigens and immune checkpoint ex vivo. Methods: Tumoroids measuring 150 μm in size retaining tumor cell heterogeneity, tumor-resident immune cells, stromal components, and extracellular matrix interaction were prepared from human endometrial and colorectal tumors. Tumoroids were cryopreserved and were selected based on tumor antigen status. Samples were treated for 72 hours ex vivo with antibody-drug conjugates, chimeric antigen receptor (CAR)T cells, or bispecific antibodies alone and in combinations. Treatment-mediated changes in tumor cell killing and tumor immune microenvironment were investigated. Results: 3D high throughput confocal imaging and Nilogen Oncosystem’s proprietary algorithm were used to detect and analyze treatment-induced tumor cell killing activity in tumoroids. The impact of ex vivo treatment by different modalities in combination with chemotherapeutic agents upon tumor resident immune cell populations was monitored by deep immune phenotyping and multiplex cytokine release assay. Based on the ex vivo responses tumors were assigned to treatment sensitive and resistant groups. Correlative analysis was performed and compared with detailed clinicopathologic data that is readily available for Biorepository tumors. Conclusions: The 3D-EXpress platform using cryopreserved 3D tumoroids with intact tumor microenvironment is an effective tool for the pre-clinical assessment of rational drug combinations for treatment of solid tumors. Furthermore, the 3D-EXpress platform provides unique insight into the microenvironment of both treatment responsive and non-responsive tumors and can aid in the development of patient-centered therapeutic regimens. Citation Format: Vanessa Garrido, Michelle Ataya, Nisha R. Dhanushkodi, Seth Currlin, Alliyah Humphrey, Jared Ehrhart, Rikhia Chakraborty. 3D-EXpress - an ex vivo platform using viably cryopreserved tumoroids for rapid assessment of targeted therapeutic outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6782.

Mckelveyite group minerals – Part 4: Alicewilsonite-(YLa), Na2Sr2YLa(CO3)6 ⋅ 3H2O, a new lanthanum-dominant species from the Paratoo mine, Australia

Abstract. The new mckelveyite group mineral, alicewilsonite-(YLa), Na2Sr2YLa(CO3)6 ⋅ 3H2O, was found together with kamphaugite-(Y), paratooite-(Y), bastnäsite-(La), and decrespignyite-(Y) coating along fractures in dolomite at the Paratoo copper mine, South Australia, Australia. It occurs as pale pink to colourless pseudohexagonal tabular crystals up to 150 µm in size. The streak is white; the lustre is vitreous. The mineral has no cleavage. Dcalc is 3.37 g cm−3. Alicewilsonite-(YLa) is optically biaxial (−), α = 1.556(2), β= 1.582(2), γ= 1.592(2), 2V (meas.) = 60(2)°, 2V (calc.) = 63° (589 nm). The IR spectrum is reported. The composition (wt %, average of seven analyses) is Na2O 7.43, CaO 2.00, SrO 18.43, BaO 1.64, Y2O3 9.59, La2O3 11.74, Pr2O3 1.29, Nd2O3 5.74, Sm2O3 0.44, Eu2O3 0.09, Gd2O3 0.95, Dy2O3 1.15, Ho2O3 0.25, Er2O3 0.89, Yb2O3 0.29, CO2 29.78, H2O 6.18, total 97.88. The empirical formula calculated on the basis of six cations with 3 H2O molecules is as follows: Na2.10Ca0.31Sr1.56Ba0.10Y0.74La0.63Pr0.07 Nd0.30Sm0.03Eu0.01Gd0.04Dy0.05Ho0.01Er0.04 Yb0.01(CO3)5.92(H2O)3. The mineral is triclinic, P1, a= 8.9839(2), b= 8.9728(3), c= 6.7441(2) Å, α= 102.812(2)°, β= 116.424(2)°, γ= 60.128(2)°, and V= 422.17(2) Å3 and Z= 1. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are 6.03(43)(001), 4.355(100)(11‾0, 2‾1‾1, 120), 4.020(30)(1‾11, 210, 1‾2‾1), 3.188(29)(2‾1‾2, 11‾1, 121), 2.819(96)(002, 1‾12, 211, 1‾2‾2), 2.592(40)(3‾01, 030, 3‾3‾1), 2.228(33)(2‾21, 4‾2‾1, 2‾4‾1). 2.011(36)(2‾22, 003, 420, 2‾4‾2), 1.9671(32)(3‾03, 301, 03‾2, 032, 3‾3‾3, 331). The crystal structure was solved and refined from single-crystal X-ray diffraction data (R1= 0.058).

Škáchaite, CaCo(CO3)2, a new member of the dolomite group, from the Brod deposit near Příbram, Czech Republic

Abstract Škáchaite (IMA2022–143) is a new mineral species discovered in samples from the hydrothermal vein B117, shaft No. 6 at the Brod deposit of the uranium and base-metal Příbram ore district, central Bohemia, Czech Republic. Škáchaite is a Co-dominant member of the dolomite group and forms anhedral grains up to 50 μm in size and as 20–100 μm thick growth zones in škáchaite–dolomite crystals as a part of carbonate (dolomite, calcite, siderite, spherocobaltite, ankerite, kutnohorite and minrecordite) gangue, associated with native silver, sulfides and arsenides. Škáchaite is pale to bright pink with vitreous lustre. The Mohs hardness is ca. 3½–4, similar to other members of the dolomite group. The calculated density is 3.140 g.cm–3. Škáchaite is optically uniaxial (–); the indices of refraction are ω = 1.741(3) and ɛ = 1.535(3). On the basis of electron-microprobe analyses, its empirical formula is Ca1.00(Co0.45Mg0.38Ca0.08Fe0.05Mn0.03Zn0.01)Σ1.00(CO3)2. The ideal formula is CaCo(CO3)2, which requires (in wt.%) CaO 25.60, CoO 34.21, CO2 40.19, a total of 100.00. Škáchaite is trigonal, R $\bar{3}$ , with unit-cell parameters a = 4.8177(18), c = 16.093(7) Å, V = 323.5(2) Å3 and Z = 3. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å, (Irel, %) hkl] are: 3.704 (13) 10 $\bar{2}$ ; 2.896 (100) 104; 2.409 (15) 110; 2.019 (17) 202; 1.812 (19) 10 $\bar{8}$ ; and 1.792 (16) 11 $\bar{6}$ . According to the single-crystal X-ray diffraction data (R1 = 0.0304 for 94 reflections with [I > 3σ(I)]), the crystal structure of škáchaite is isotypic with its Mg-analogue, dolomite. The Raman spectrum of škáchaite, as well as the tentative assignment of observed bands, are given in this paper. The mineral is named in honour of Pavel Škácha, a Czech mineralogist and curator of the mineralogical collection of the Mining Museum Příbram, Czech Republic.

Synthesis, XPS and NEXAFS spectroscopy study of Zn, Cr codoped bismuth tantalate pyrochlores

The study investigated the formation of inhomophase ceramics through Zn doping in Bi2СrTa2O9.5–Δ. It was found that all Bi2ZnxCr1–xTa2O9.5–Δ (0.3 ≤ x ≤ 0.7) investigated samples crystallized in the pyrochlore structural type (sp. Gr. Fd-3m) and contained an admixture of triclinic β-BiTaO4 (up to 24 wt %, sp. gr. P-1), with the admixture concentration proportional to the degree of zinc doping. It was shown that impurities in the samples could be eliminated by creating a defective bismuth sublattice proportional to the impurity content, resulting in single-phase Bi2–yZnxCr1–xTa2O9.5–Δ (y ≤ 0.5, 0.3 ≤ x ≤ 0.7) samples with the pyrochlore structure. The unit cell parameter of pyrochlore increased with an increase in zinc ion content in the samples from 10.4493 Å (x = 0.3) to 10.4976 Å (x = 0.7). The microstructure of ceramics was represented by individual slightly melted grains 0.5–2 μm in size, which increased in size and fuse with each other with an increase in zinc content. The near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data showed that zinc doping did not change the oxidation degree of bismuth and tantalum in pyrochlore, with the ions in charge states Bi(+3), Zn(+2) and Ta(+5). The study also observed an energy shift of the absorption band in the Ta 4f spectrum toward lower energies (ΔE = 0.55 eV) characteristic of tantalum ions with an effective charge (+5–δ) and a shift of the Bi 4f7/2 and Bi 4f5/2 bands shift to lower energies with increase in x(Zn), due to the distribution of some Zn(II) ions in the bismuth position. The oxidation degree of chromium ions in the samples was mainly (+3), with some chromium ions oxidized and having an oxidation degree close to (+6) according to NEXAFS data. The studied ceramics showed promise as dielectrics for multilayer ceramic capacitors and devices for microwave applications due to their low sintering temperature and high porosity.

Modelling the effect of shape on atmospheric microplastic transport

Microplastics are particles less than 5 mm in size and are a growing scientific concern, given the potential harm caused across ecosystems as a result of the global use of plastics. Most microplastics are non-spherical in shape, however, most atmospheric modelling studies to date treat microplastics as simple spheres when assessing transport. To further understand the effects of shape and size on atmospheric microplastic transport, the HYSPLIT model was utilized to identify potential differences. It was shown that the extent of microplastic transport and deposition varied significantly by shape for particles larger than 6 μm, but for particles smaller than 6 μm, the differences were not significant. Long fibres deposited over a 32% greater area than spherical particles at the largest equivalent size of 23.5 μm. The maximum deposition area occurred for particles with an equivalent size of 4.5 μm, varying in deposition area by less than 0.25% by the shapes considered. As particles smaller than 10 μm have a large potential to cause adverse health effects and shape affects transport in the 6 μm–10 μm size range, accurately modelling the shape of atmospheric microplastic transport is crucial to determining the range and amount of deposition globally.

Spray-deposition of graphene/polymer thin coatings on polyimide sheets for lunar dust adhesion mitigation

NASA seeks to develop technologies to mitigate dust accumulation from planetary surfaces on robotic and human systems hardware during planned space exploration missions. With a return to the Lunar surface, lunar dust threatens the durability and reusability of components and vehicles due to its fine, jagged morphology and highly abrasive nature. Lunar dust consists of particles less than 60 μm in size that are chemically reactive, electrostatically and sometimes magnetically charged. Unique materials and technologies that reduce or mitigate lunar dust adhesion will be critical to support long duration missions and eventual sustained presence on the lunar surface. The goal of this work was to prepare dust resistant, space durable polymer films to satisfy dust accumulation mitigation needs for future NASA missions. In this regard, several graphene coated polyimide thin films have been developed with surface resistivity properties in the range of 103 Ω/sq to 1011 Ω/sq and evaluated for their dust adhesion performance. Raman spectroscopy was used to characterize and assess the quality of graphene ink coated sheets while surface resistivity measurements were used to assess electrical conductivity. Scratch testing and abrasion resistance measurements were used to evaluate overall abrasion performance. Water contact angle and optical microscopy were used to evaluate changes in surface topography and chemistry. Graphene coated polyimide surfaces with charge dissipative resistivity (106 Ω/sq) demonstrated a minimum in residual particle areal coverage compared to conductive and insulating surfaces.

Mechanical and thermal properties of in situ AlN/Al-12Si composite fabricated by laser powder bed fusion

This work reports on the synthesis, mechanical, and thermal properties of in situ AlN/Al-12Si composite through laser powder bed fusion (LPBF) by blending Al-12Si powder with 5 vol% nano-sized BN particles. Incorporating nano-BN particles results in (i) formation of thermally stable AlN phase, preventing Si diffusion and breakdown of cellular structure, (ii) improvement of compressive yield strength (CYS), and (iii) reduction in coefficients of thermal expansion (CTE) and thermal conductivity. In addition, compared to Al-12Si alloy, the composite exhibits grain refinement from 38.8 to 1.2 μm in size, and the alteration of columnar grains (Al-12Si) to equiaxed grains (AlN/Al-12Si). At annealing temperatures above 573 K, the CYS of the unadulterated Al-12Si alloy had a ∼ 2.1 times greater reduction (from 285 to 200 MPa) compared to that of the composites (from 301 to 260 MPa). The formation of the AlN phase mitigates the significant reduction in CYS. The CTE of Al-12Si and AlN/Al-12Si are 27.3 × 10−6 K−1 and 24.3 × 10−6 K−1 respectively. There is good agreement between the measured CYS results and the calculated strengthening mechanisms. This work offers both theoretical insights and experimental data to support the use of LPBF AlN/Al-12Si composite in low- and moderate-temperature applications.

Occurrence, distribution and sources of microplastics in typical marine recirculating aquaculture system (RAS) in China: The critical role of RAS operating time and microfilter

Industrial mariculture, a vital means of providing high quality protein to humans, is a potential source of microplastics (MPs) which have recently received increasing attention. This study investigated the occurrence and distribution of microplastics in feed, source water and recirculating aquaculture system (RAS) with long & short operating times as well as in fish from typical industrial mariculture farms in China. Results showed that microplastics occurred in all samples with the average concentration of 3.53 ± 1.39 particles/g, 0.70 ± 0.17 particles/L, 1.53 ± 0.21 particles/L and 2.21 ± 0.62 particles/individual for feed, source water, RAS and fish, respectively. Microplastics were mainly fiber in shape, blue in color and 20–500 μm in size. Compared with short operated RAS, long operating time led to higher microplastic concentration in RAS, especially that of microplastic in 20–500 μm, granular and blue. Regardless of short or long operating time, microplastics in RAS mainly gathered in culture tank, tank before microfilter and fixed-bed biological filter, and the microfilter removed efficiently the microplastic with the shape of film, granule, fragment as well as those with size > 1000 μm. As for the polymer types, polyamide (PA, 71.9 %) and polyethylene terephthalate (PET, 65.7 %) dominated in feed and source water, respectively, which may be the reason for the high proportion of PA (38.8 % and 26.4 %) and PET (31.8 % and 30.2 %) in RAS and fish. In addition, polypropylene (PP) was also detected in RAS (18.7 %) and fish (22.6 %), indicating that other plastic facilities such as PP brush carrier also made a contribution. Positive matrix factorization (PMF) model revealed three sources of MP in RAS, namely plastic facilities, industrial sewage and plastic packaging products. Our results provided a theoretical basis for the management of MP in RAS.

Calcination-based direct extraction of hydroxyapatite from bovine bone waste

ABSTRACT The main chemical components of waste cow bones are apatite minerals, especially those containing calcium and phosphorus. This study investigated whether this bone could produce extracted hydroxyapatite through calcining at 900° C for different holding times (1–6 h). An average mass loss of 45% occurred in this experiment during the preparation of bone powders, which involved crushing and further calcining at this temperature. The quantitative XRD analysis showed that 99.97 wt.% hydroxyapatite and over 0.3 wt.% calcite were present in the raw and as-calcined bone powders, with trace amounts of CaFe3O5 (calcium ferrite) phases appearing in the calcined product. Depending on the holding calcining times, SEM images of the calcined bovine powders revealed aggregate sizes ranging from 0.5–3 µm and crystallite (grain) sizes ranging from 70 to 340 nm in all calcium-phosphate powder products. Following EDX analysis of all sample surfaces, possible calcium-deficient hydroxyapatite instead of hydroxyapatite formed, as evidenced by the calcined product's Ca/P ratio exceeding 1.67. Additionally, calcining cow bones for 5–6 h at 900° C yielded a high-purity nano-crystalline hydroxyapatite powder precursor in biomedical applications.

Size Control of Biomimetic Curved-Edge Vaterite with Chiral Toroid Morphology via Sonochemical Synthesis.

The metastable vaterite polymorph of calcium carbonate (CaCO3) holds significant practical importance, particularly in regenerative medicine, drug delivery, and various personal care products. Controlling the size and morphology of vaterite particles is crucial for biomedical applications. This study explored the synergistic effect of ultrasonic (US) irradiation and acidic amino acids on CaCO3 synthesis, specifically the size, dispersity, and crystallographic phase of curved-edge vaterite with chiral toroids (chiral-curved vaterite). We employed 40 kHz US irradiation and introduced L- or D-aspartic acid as an additive for the formation of spheroidal chiral-curved vaterite in an aqueous solution of CaCl2 and Na2CO3 at 20 ± 1 °C. Chiral-curved vaterites precipitated through mechanical stirring (without US irradiation) exhibited a particle size of approximately 15 μm, whereas those formed under US irradiation were approximately 6 μm in size and retained their chiral topoid morphology. When a fluorescent dye was used for the analysis of loading efficiency, the size-reduced vaterites with chiral morphology, produced through US irradiation, exhibited a larger loading efficiency than the vaterites produced without US irradiation. These results hold significant value for the preparation of biomimetic chiral-curved CaCO3, specifically size-reduced vaterites, as versatile biomaterials for material filling, drug delivery, and bone regeneration.

Reductive stress and cytotoxicity in the swollen river mussel (Unio tumidus) exposed to microplastics and salinomycin

Multistress effects lead to unpredicted consequences in aquatic ecotoxicology and are extremely concerning. The goal of this study was to trace how specific effects of the antibiotic salinomycin (Sal) and microplastics (MP) on the bivalve molluscs are manifested in the combined environmentally relevant exposures. Unio tumidus specimens were treated with Sal (0.6 μg L−1), MP (1 mg L−1, 2 μm size), and both at 18 °C (Mix) and 25 °C (MixT) for 14 days. The redox stress and apoptotic enzyme responses and the balance of Zn/Cu in the digestive gland were analyzed. The shared signs of stress included a decrease in NAD+/NADH and Zn/Cu ratios and lysosomal integrity and an increase in Zn-metallothioneins and cholinesterase levels. MP caused a decrease in the glutathione (GSH) concentration and redox state, total antioxidant capacity, and Zn levels. MP and Mix induced coordinated apoptotic/autophagy activities, increasing caspase-3 and cathepsin D (CtD) total and extralysosomal levels. Sal activated caspase-3 only and increased by five times Cu level in the tissue. Due to the discriminant analysis, the cumulative effect was evident in the combined exposure at 18 °C. However, under heating, the levels of NAD+, NADH, GSH, GSH/GSSG and metallothionein-related thiols were decreased, and coordination of the cytosolic and lysosomal death stimuli was distorted, confirming that heating and pollution could exert unexpected synergistic effects on aquatic life.