Ng Cm-2 Research Articles

Surface Heterogeneity at the Polymer-Food Interface Influences Ag Migration from Plastic Packaging Incorporating Ag-Exchanged Zeolites.

Silver-enabled polymers, with their antimicrobial properties, could prolong the shelf life and maintain quality in packaged foods. However, there is limited understanding about how the Ag form in the polymer, food chemistry, and other factors affect the transfer (migration) of Ag from the polymer to the food under the intended conditions of use. In this study, we investigated the release of Ag from polymer composites (PCs) incorporating two different Ag-exchanged zeolites (Ag-Y), which have been explored as potential scaffolds for loading high concentrations of Ag within common polymers. We manufactured two Ag-Y films based on low-density polyethylene (LDPE): one incorporating ionic Ag (Ag+) and one incorporating nanoparticulate Ag (AgNPs), each with similar initial Ag concentrations. Then, we assessed the migration of Ag out of these PCs into food simulants under accelerated room temperature storage conditions. In all simulants investigated, the Ag+-Y/LDPE film exhibited a higher migration of Ag compared to the AgNP-Y/LDPE film, suggesting a lower fraction of readily releasable Ag in the latter material. Total Ag migration from AgNP-Y/LDPE over 10 days at 40 °C was 11.10 ± 2.05 ng cm-2 of packaging surface area in water, 7.63 ± 1.59 ng cm-2 in a 9 wt % aqueous sucrose solution, and 21.29 ± 1.98 ng cm-2 in a commercial sweetened carbonated beverage (Squirt). In contrast, Ag migration from Ag+-Y/LDPE was measured at 49.61 ± 3.46, 57.48 ± 9.65, and 91.54 ± 5.58 ng cm-2 in water, sucrose solution, and Squirt drink, respectively. Surface characterization techniques, including atomic force microscopy (AFM), scanning electron microscopy (SEM), and conductivity measurements, revealed the presence of exposed zeolite particles at the surface of the films, suggesting that direct interactions between Ag-exchanged zeolites and food components at the simulant-polymer interface play an important role in determining Ag migration from Ag-Y/LDPE PCs.

Pneumatic spray delivery-based fixed spray system configuration optimization for efficient agrochemical application in modern vineyards.

The hydraulic spray delivery (HSD)-based solid set canopy delivery system (SSCDS) emitter configuration has been optimized for agrochemical applications in vertical shoot position (VSP) vineyards. It uses cost-prohibitive emitters, and their placement restricts the mechanical pruning activities. Therefore, this study focused on optimizing the spray performance of a pneumatic spray delivery (PSD)-based SSCDS variant that addresses the earlier issues. Three PSD-SSCDS emitter configurations (C1-C3) were designed using modified low-cost emitters (E1: modified flat fan, E2: 90° modular flat fan) for agrochemical applications in VSP vineyards. C1 had an E1 installed on trellis posts at 1.67 m above ground level. C2 had a pair of E2 installed per vine at 0.3 m below the cordon, while C3 combined the emitter placement of C1 and C2. The spray deposition (ng cm-2) and coverage (%) were quantified (mean ± standard error) using mylar cards and water-sensitive paper samplers placed within the canopy, respectively. Spray deposition for C1, C2, and C3 was 301.12 ± 63.30, 347.9 ± 66.29, and 837.6 ± 92.53 ng cm-2, respectively. Whereas spray coverage for corresponding configurations was 18.02 ± 2.63, 8.98 ± 1.84, and 28.84 ± 2.46%, respectively. Overall, configuration C3 provided significantly higher spray deposition and coverage than C1 and C2. Substantially reduced system installation cost and emitter density per hectare with improved spray performance were achieved by C3 compared to earlier optimized HSD-SSCDS configuration in the VSP vineyards. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of disposable protective garments against epoxy resin permeation and penetration from anti-corrosion coatings.

Epoxy-based resin formulations are a frequent cause of allergic and irritant contact dermatitis in the construction and painting industries. Cases of epoxy resin contact dermatitis continue to persist across many sectors and are likely attributable to the growing use of epoxy products, including epoxy-based anti-corrosion coatings and inadequate skin protection. There are no published performance data against epoxy resins for garment materials and gloves to guide proper material selection in the workplace. The objective of this study was to evaluate the resistance of 5 protective garment materials against permeation and penetration by bisphenol A diglycidyl ether and its higher oligomers found commonly in epoxy-based anti-corrosion coatings. Five disposable garment materials were evaluated for resistance to bisphenol A diglycidyl ether monomers and oligomers during contact with epoxy-based anti-corrosion coatings, including latex gloves, nitrile gloves, Tyvek coveralls, polypropylene/polyethylene (PP/PE) coveralls, and a cotton T-shirt. A permeation test cell system was used to evaluate each garment material against an epoxy-based zinc-rich primer and an epoxy-based intermediate coating using a realistic application method. Glass fiber filters were used to collect permeating and penetrating epoxy resin during a 120-min test period. Bisphenol A diglycidyl ether quantification was performed with high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. Paint loading, coating thickness, and homogeneity were assessed on polytetrafluoroethylene filters sprayed in series in permeation test cells. Latex gloves provided the least resistance to permeation by BADGE in coating formulations, with a maximum cumulative permeation over the 2-h test interval of 21.7 ng cm-2 with the primer and 513.8 ng cm-2 with the intermediate coating product. Nitrile gloves were not permeated by either coating formulation. The Tyvek coveralls provided greater protection as compared to the PP/PE coveralls. The cotton T-shirt was penetrated by bisphenol A diglycidyl ether more frequently than any of the tested garment materials and resulted in a maximum cumulative penetration of 128 ng cm-2 with the primer and 28.0 ng cm-2 with the intermediate coating. Although all the garment materials evaluated during this study provided sufficient protection to prevent cumulative permeation in excess of the established acceptable permeation thresholds, the use of nitrile gloves and Tyvek coverall is highly recommended to minimize skin exposure to bisphenol A diglycidyl ether. We recommend cotton T-shirts to be used under Tyvek coveralls as a secondary layer of skin protection and for added comfort, but not as a primary protection layer.

Comparative Spray Performance of a Solid Set Canopy Delivery System and an Airblast Sprayer in Modern Apple Orchards

Highlights Airblast sprayer applications in modern apple orchards can produce high off-target drift. A pneumatic spray delivery based solid set canopy delivery system (PSD-SSCDS) can be an alternative solution. PSD-SSCDS had comparable spray deposition, but lower spray coverage compared to airblast sprayer. Airblast sprayer had significantly higher losses to the ground and aerial drift. PSD-SSCDS confined ground drift within 4.1 m with minimal spray losses to air. Abstract. A pneumatic spray delivery-based solid set canopy delivery system (PSD-SSCDS) has been successfully configured for efficient spray applications in modern apple orchards typical of the state of Washington state. This study investigates the spray performance of optimized PSD-SSCDS against an axial-fan airblast sprayer in terms of spray deposition, coverage, and off-target drift in a tall spindle architecture of a commercial apple orchard. For field evaluation, mylar cards and water sensitive paper samplers were placed in different canopy zones on either side of the leaf surface, and 500 ppm of biodegradable fluorescent tracer solution was sprayed with PSD-SSCDS and an airblast sprayer. Additionally, aerial and downwind samplers were installed to evaluate ground runoff and drift, as well as aerial drift. The spray deposited on the mylar cards was analyzed using fluorometry, and spray coverage on WSPs was evaluated using image processing techniques. PSD-SSCDS (645.0 ± 94.7 ng cm-2, mean ± standard error) and an airblast sprayer treatment (661.6 ± 26.9 ng cm-2) had comparable mean spray deposition with no significant difference in different canopy zones for both treatments. However, the spray coverage was significantly higher for the airblast sprayer (32.7 ± 2.4%) compared to PSD-SSCDS (22.5 ± 3.1%). These differences are likely due to air-assist in airblast spraying, which is absent in PSD-SSCDS. Evidently, the airblast sprayer had significantly higher losses to the ground and aerial drift compared to PSD-SSCDS, as the ground drift for the latter was mostly confined within 4.1 m downwind of the sprayed row and spray losses to air were minimal. Keywords: Crop protection, Fixed spray delivery, Off-target drift, Pneumatic spray delivery, Spray coverage, Spray deposition.

Selective sensing of picric acid using a Zn(II)-metallacycle: experimental and theoretical validation of the sensing mechanism and quantitative analysis of sensitivity in contact mode detection.

A combination of N,N',N''-tris(3-pyridyl)-1,3,5-benzenetricarboxamide (L1) and p-chlorobenzoic acid (HL2) with Zn(NO3)2·6H2O resulted in the formation of a dinuclear metallacycle [ZnL1(L2)2(DMF)2]2 (1(DMF)4). In 1(DMF)4, the Zn(II) centre adopts a square pyramidal geometry, while one of the pyridyl N out of the three pyridyl groups in L1 remained uncoordinated. Solvated DMF molecules are present in 1(DMF)4. The structural and chemical nature of 1(DMF)4 is effective for it to act as a potential fluorescent probe for the detection of nitroaromatic compounds. It is observed that the probe, 1(DMF)4, could selectively detect picric acid (PA) among various aromatic compounds in solution (DMSO), while the solid state (contact mode) detection showed a positive sensing response for the nitrophenols (PA: 87% quenching efficiency, 2,4-dinitrophenol (2,4-DNP): 57% quenching efficiency and 4-nitrophenol (4-NP): 40% quenching efficiency). The limit of detection (LOD) of PA by the probe in DMSO was found to be 6.8 × 10-11 M while the LOD in contact mode detection was estimated to be 0.49 ng cm-2. The mechanism of selective detection of PA by 1(DMF)4 in DMSO was analyzed through photophysical studies, 1H-NMR experiments and also by density functional theory (DFT) calculations. The effective overlap of the absorption spectrum of 1(DMF)4 and emission spectrum of PA in DMSO suggests that the Förster resonance energy transfer (FRET) is responsible for quenching phenomena in DMSO. The DFT calculations and molecular docking studies showed the adduct formation due to the favorable interactions between 1(DMF)4 and PA in DMSO, while negligible interactions were observed between 1(DMF)4 with other aromatic compounds. The experimental and DFT studies showed that the efficient sensing ability of PA by 1(DMF)4 in the solid-state was due to photoelectron transfer (PET) and FRET phenomena described herein.

SERS detection of thiram using a 3D sea cucumber-like composite flexible porous substrate.

Nowadays, trace detection of thiram is in urgent demand due to its widespread application in agriculture and significant harmful effects on public health. In this work, a three-dimensional (3D) sea cucumber-like flexible porous surface-enhanced Raman scattering (SERS) substrate composed of a poly(vinylidene fluoride) (PVDF) membrane, ZnO nanorods, gold films, and Ag nanoparticles (Ag/Au/ZnO/P) has been established for the highly sensitive detection of thiram. The substrate takes advantage of the 3D morphology of the Ag/Au/ZnO system on a flexible porous PVDF membrane to produce abundant plasmonic hot spots. Meanwhile, the employment of an AgNPs/Au shell system combined the benefits of both gold and silver metals, thus guaranteeing stable and sensitive detection. With 4-mercaptobenzoic acid (4-MBA) as a probe molecule, the Ag/Au/ZnO/P substrate exhibited excellent linear detection in the range of 10-11-10-5 M, with a correlation coefficient (R2) of 0.99 and an enhancement cofactor of 7.09 × 107. The substrate exhibited excellent uniformity with a related standard deviation (RSD) value of 3.82% and demonstrated high stability during a 15 d-storage test. In addition, the substrate could detect thiram in an aqueous solution at concentrations as low as 10-10 M with excellent selectivity. Meanwhile, thiram on the surface of apple peel could be easily detected by the Ag/Au/ZnO/P substrate with the "paste-and-peel" method in less than 10 s, and the detection limit could be as low as 0.48 ng cm-2. Overall, the remarkable performance of the Ag/Au/ZnO/P SERS substrate demonstrated its great potential for the environmental monitoring of thiram.

Cloth-Air Partitioning of Neutral Per- and Polyfluoroalkyl Substances (PFAS) in North Carolina Homes during the Indoor PFAS Assessment (IPA) Campaign.

Partitioning of per- and polyfluoroalkyl substances (PFAS) to indoor materials, including clothing, may prolong the residence time of PFAS indoors and contribute to exposure. During the Indoor PFAS Assessment (IPA) Campaign, we measured concentrations of nine neutral PFAS in air and cotton cloth in 11 homes in North Carolina, for up to 9 months. Fluorotelomer alcohols (i.e., 6:2 FTOH, 8:2 FTOH, and 10:2 FTOH) are the dominant target species in indoor air, with concentrations ranging from 1.8 to 49 ng m-3, 1.2 to 53 ng m-3, and 0.21 to 5.7 ng m-3, respectively. In cloth, perfluorooctane sulfonamidoethanols (i.e., MeFOSE and EtFOSE) accumulated most significantly over time, reaching concentrations of up to 0.26 ng cm-2 and 0.24 ng cm-2, respectively. From paired measurements of neutral PFAS in air and suspended cloth, we derived cloth-air partition coefficients (Kca) for 6:2, 8:2, and 10:2 FTOH; ethylperfluorooctane sulfonamide (EtFOSA); MeFOSE; and EtFOSE. Mean log(Kca) values range from 4.7 to 6.6 and are positively correlated with the octanol-air partition coefficient. We investigated the effect of the cloth storage method on PFAS accumulation and the influence of home characteristics on air concentrations. Temperature had the overall greatest effect. This study provides valuable insights into PFAS distribution, fate, and exposure indoors.

Mitigation of pesticide residue levels in the exposed dermal regions of occupationally exposed farmworkers by use of personal protective equipment.

Unsafe pesticide handling practices with the limited use of personal protective equipment (PPE) by the Indian farming groups lead to an increased risk of exposure to pesticides. Therefore, a community-based follow-up study based on dosimeters, wipes, and hand-wash technique was carried out to evaluate the dermal exposure to pesticides and to analyze the impact of the usage of PPE on minimizing the exposure among the farmworkers of Rangareddy district, Telangana, India. Risk in terms of hazard quotient (HQ), hazard index (HI), and safety analysis as margins of safety was assessed. Farmworkers averaged 18 years of farming experience and showed resistance to adopting good agricultural practices. Ten pesticide residues were detected in concentrations ranging from 0.000 to 246 mg ml-1 in hand-wash, 0.000 to 198.33 ng cm-2 in patch dosimeter, and 0.000 to 1,740 ng cm-2 in wipe samples collected from farmworkers not using PPE. The second phase includes the intervention study results that revealed a significant reduction both in the concentrations and the number of pesticide residues detected in the hand-wash, patch, and wipe samples of the farmworkers who have used the PPE provided to them (p < 0.01). Furthermore, the probabilistic health risk assessment in terms of the HQ values ranged from 0.02 to 1029.82, and HI was >1, suggesting the non-carcinogenic risks associated with dermal exposure to pesticides among them. Additionally, the safety risk assessment in terms of the margin of safety suggests that they follow risky handling practices. The study confirms that farmworkers are exposed to pesticides and emphasizes the significance of using PPE in reducing the risk.

Initial assessment of multi-compound antineoplastic drug surface contamination in Argentinean healthcare centers: Insights into occupational exposures in South America.

Antineoplastic drug contamination can result in severe health effects for healthcare workers exposed to them. Despite the worldwide growing concern regarding these drugs and sustained monitoring efforts in developed countries, there is almost no data about surface contamination levels in Argentina, in particular, and South America, in general. Antineoplastic drug contamination was measured in three Argentinean public hospitals (pharmacy and daycare center areas) by surface wiping and liquid chromatography coupled with tandem mass spectrometry. Eleven drugs were detected, in 51 of 58 sampled surfaces, in variable concentrations from 0.00064 to 7.3 ng cm-2, with cyclophosphamide, gemcitabine, and paclitaxel as the most prevalent drugs. This highly variable antineoplastic distribution reflects differences in facility layout, number of patients, antineoplastic drug use, etc., at each hospital. Values exceeding the 1 ng cm-2 threshold were detected in 13 surfaces of the two hospitals handling the largest amounts of antineoplastic drugs. The cyclophosphamide 75th percentile averaged 0.030 ng cm-2 comparable to the high values reported more than 10 years ago for developed countries, emphasizing the potential of reducing antineoplastic contamination by implementing routine monitoring and improved cleaning and handling procedures. This study is the first survey of multi-compound surface antineoplastic contamination in Argentinean (and South American) hospitals, providing a baseline against which future studies can be compared. Widespread antineoplastic contamination has been detected on numerous surfaces, with concentrations surpassing suggested threshold exposure levels (1 ng cm-1) for some surfaces in two of the sampled hospitals.

Modified paper-based substrates fabricated via electrostatic attraction of gold nanospheres for non-destructive detection of pesticides based on surface-enhanced Raman spectroscopy.

Flexible surface-enhanced Raman spectroscopy (SERS) substrates such as paper-based substrates show great potential for rapid detection of residual chemicals on food surfaces. However, controlling the density and distribution of metallic nanoparticles adsorbed on the paper is still challenging. The amount of gold (Au) nanospheres (51 ± 4 nm) attached on the filter paper modified with 3-aminopropyltriethoxysilane (APTES) was tunable, increasing as the level of APTES (2.5-15.0 g kg-1 ) applied for paper modification increased. Moreover, the Au nanospheres were relative evenly distributed on the filter paper modified with 2.5-10.0 g kg-1 of APTES, which resulted in excellent intra- and inter-reproducibility of SERS signals for pesticides including thiram, diquat dibromide, and paraquat dichloride (relative standard deviation = 2.2-10.1%). The modified paper-based substrate could be used to detect as low as 0.05-0.2 mg L-1 of pesticides in standard solutions, and as low as 5-20 ng cm-2 of residual pesticides on apple skins with minimum sample pretreatment. This paper-based substrate with tunable feature for the density and distribution of nanoparticles is applicable for rapid SERS detection of residual pesticides in fruits and vegetables. © 2023 Society of Chemical Industry.

Temporal trends of organophosphate esters in a sediment core from the tidal flat of Liao River estuary, Northeast China

The historical trends and inventory of organophosphate esters (OPEs) were investigated based on depth profiles of OPEs in sediment core collected from the tidal flat of the Liao River estuary in northeastern China. The concentration of ∑13OPEs in sediment core has increased continuously since records began, reaching a peak of 10.8 ng g-1 dry weight (dw) in the 1960s, then began to decline and fall to a low of 3.91 ng g-1 dw in the 1980s, before rising again and increasing to 20.4 ng g-1 dw in the 2000s. After a brief decline, It started to increase again and reached a peak of 27.0 ng g-1 dw in 2018. Tributyl-n-phosphate was found in each layer of the sediment core, accounting for 31.9 - 100% of ∑13OPEs. The fluxes of OPEs ranged from 46.5 to 105 ng cm-2 y-1 in the sediment layers deposited between 2007 and 2018. The inventory of OPEs in the sediment core was estimated to be 1541 ng cm-2. This work reports for the first time the historical contamination trends of OPEs in Chinese sediments, which is important for assessing the environmental risk of OPEs.

Effects of organic carbon burial on biomarker component changes in contamination in northeast Dianchi watershed.

The upper reaches of the Yangtze River have experienced increasing anthropogenic stress. Quantitative tracing of carbon (C) sources and ecological risks through biomarkers i.e., polycyclic aromatic hydrocarbons (PAHs) and n-alkanes is significant for C neutrality and sequestration. Here, source and sink patterns, and factors influencing C burial and biomarker components in a small catchment of Dianchi Lake were explored. The sediment core covered the period 1855-2019. Before 1945, the organic C accumulation rate (OCAR) ranged from 0.71 to 5.12mgcm-2 yr-1, and the PAHs and n-alkanes fluxes were 106.99-616.09ngcm-2 yr-1 and 5.56-31.37μgcm-2 yr-1. During 1945-2005, the OCAR, PAH, and n-alkane burial rapidly increased from 3.19 to 16.17mgcm-2 yr-1, 230.40 to 2538.81ngcm-2 yr-1, and 11.63 to 61.90μgcm-2 yr-1. During 1855-2019, deposition fluxes of PAHs and n-alkanes increased 13.01 and 9.14 times, resulting in increased C burial, driven by environmental changes. A PMF model and the diagnostic ratio indicated that PAHs from coal combustion and traffic emission increased from 22.32% to 65.20% during 1855-2019. The PAH concentrations reflected normal-moderate contamination and potential risks to the aquatic environment. The results facilitate a comprehensive understanding of anthropogenic-driven interactions between increasing OC burial and ecological risks.

Nanotechnology and narasin: a powerful combination against acne.

Acne vulgaris is widely regarded as the most prevalent skin disorder characterized by painful, inflammatory skin lesions that are primarily attributed to the pathogenic actions of Cutibacterium acnes (C. acnes). To improve the clinical management of this disease, there is a pressing clinical demand to develop innovative antibacterial therapies that utilize novel mechanisms. The current research aimed to discover the antibacterial efficacy of narasin (NAR), a polyether ionophore, against drug-resistant acne bacteria. In addition, the study aimed to formulate self-nanomicellizing solid dispersions (SNMSD), utilizing Soluplus® (SOL), as a drug delivery system to incorporate NAR and selectively target the lipophilic C. acnes abundant environments within the skin. Furthermore, the study aimed to investigate the ex vivo deposition and permeation of NAR into the various layers of the skin using full-thickness porcine ear skin as a model skin. By encapsulating NAR within spherical polymeric micelles (dn < 80 nm) aqueous solubility was significantly increased by approximately 100-fold (from <40 μg mL-1 to 4600 μg mL-1). Following optimization, the micelle solution was integrated into a gel formulation (containing 0.2% w/v NAR) and evaluated for stability over 4 weeks at room temperature (drug content >98%). Results from drug deposition and permeation experiments demonstrated that the deposition of NAR from the NAR-micelle solution and its gel formulation into the lipophilic stratum corneum (19 835.60 ± 6237.89 ng cm-2 and 40 601.14 ± 3736.09 ng cm-2) and epidermis (19 347 ± 1912.98 ng cm-2 and 18 763.54 ± 580.77 ng cm-2) was superior to that of NAR in solution, which failed to penetrate any skin layers. In conclusion, the outcomes of this study provide evidence that NAR exhibits promising activity against antimicrobial resistant strains of C. acnes (MIC range ≤0.008-0.062) and that micelle nanocarriers can improve the aqueous solubility of poorly water-soluble drugs. Furthermore, our results highlight the ability of nanomicelles to enable selective and targeted drug delivery to the lipophilic skin layers.

Silver decahedral nanoparticles with uniform and adjustable sizes for surface-enhanced Raman scattering-based thiram residue detection.

Surface-enhanced Raman scattering (SERS) has been widely used as a sensitive molecular spectroscopy technology in food safety detection. Precise morphology control of plasmonic nanoparticles for high sensitivity and high uniformity SERS substrates remains challenging. Herein, silver decahedral nanoparticles (AgDeNPs) with uniform and adjustable sizes were synthesized by a photochemical seed-mediated method and utilized as SERS substrates for pesticide residue detection. The SERS sensitivity was demonstrated by using 4-mercaptobenzoic acid (4-MBA) as a typical model molecule, and the limit of detection (LOD) reached 1.0 × 10-13 M. The pesticide residue detection of thiram in aqueous solution and on fruit peels was successfully realized; the LODs were 1.0 × 10-11 M and 0.96 ng cm-2, respectively, and SERS repeatability was also proved. Overall, size-tunable AgDeNPs show attractive SERS performances and are expected to hold potential application in sensitive food and environmental safety detection.

"Built to Last": Plant-based Eco-friendly Durable Antibacterial Coatings.

The demand for effective and long-term durable antibacterial surfaces has been ever-growing in the past decades. A wide variety of long-lasting antibacterial surfaces developed from release-killing, active-killing, and anti-fouling strategies have demonstrated the desired effectiveness and durability so far. Most of these successful designs were developed from toxic and fossil-based materials, which failed to comply with the green design criteria. Furthermore, the longevity of these surfaces remained an unaddressed challenge. Herein, we present a disruptive paradigm that emphasizes both eco-friendliness and long-lasting antibacterial properties. A bio-based active-killing essential oil, namely carvacrol, and nonfouling carboxybetaine zwitterionic moieties were combined and incorporated into a highly bio-based polyurethane (BPU). The long-lasting active-killing property for this antibacterial BPU coating was enabled through the extended release of the bounded carvacrol via hydrolysis in an aqueous environment and compared to unbound carvacrol by liquid infusion. Also, the release of carvacrol generates zwitterionic moieties to prevent further bacterial attachment at the release site, resulting in a "kill and defend" synergistic antibacterial function in the BPU. The kinetics of the extended-release property were investigated and compared with unbound carvacrol BPU coatings; unbound carvacrol infused into BPU was quickly exhausted after 2 days of immersion in water, while the extended-release surface exhibited a nearly constant release rate of ∼128 ng cm-2 h-1 even after 45 days. The in vitro antibacterial efficiency of the BPUs was quantitatively evaluated using the modified ISO standard for cross-laboratory comparison. As a result, approximately 98.9 and 98.7% of Escherichia coli and Staphylococcus aureus were eliminated from the coating surfaces, and only a negligible variance in the antibacterial efficiency was observed after 5 cycles of test. The feasibility for practical application was also demonstrated by challenging the BPU coatings in everyday settings. This "built-to-last" design theory provided insights for future development of greener antibacterial coatings with long-term performance.

Detection of thiram on fruit surfaces and in juices with minimum sample pretreatment via a bendable and reusable substrate for surface-enhanced Raman scattering.

Surface-enhanced Raman scattering (SERS) substrates based on metallic nanoparticles locked in some flexible materials have great potential for rapid detection of pesticide residues in foods, but these substrates are generally not reusable. A bendable and reusable sponge based on polydimethylsiloxane (PDMS) and Au nanospheres was synthesized and employed as SERS substrate to analyze thiram on the surfaces of apples and grapes (20-1000 ng cm-2 ) and in their juices (0.5-5.0mg L-1 ) with minimum sample pretreatments. The lowest detectible concentrations for thiram in fruit juices and on fruit skins were 0.5mg L-1 and 20 ng cm-2 , respectively. The Au-PDMS substrate had acceptable intra-reproducibility for SERS analysis of thiram in fruit juices and on fruit skins, resulting in 3.6-16.9% relative standard deviation (RSD) for the SERS signal of the primary peak of thiram. Moreover, the Au-PDMS substrate exhibited distinguished reusability and stability, which could provide a reproducible SERS signal of thiram in apple juice even after the substrate being reused ten times (RSDs for the three major characteristic peaks of thiram were 2.7-10.5% during the ten reused cycles). This flexible and reusable Au-PDMS SERS substrate for thiram detection could be readily extended to the analysis of other trace chemicals in a broad range of foods, providing a new possibility for SERS application. © 2022 Society of Chemical Industry.

Assessing the environmental risk and mobility of cobalt in sediment near nonferrous metal mines with risk assessment indexes and the diffusive gradients in thin films (DGT) technique

The Jialing River is the tributary of the Yangtze River with the largest drainage area. In recent years, the Jialing River has suffered a series of environmental problems, such as discharge of industrial effluent and sand mining activities, which have severely threatened the aquatic ecosystem of the river. In the present study, we employed risk assessment indexes, sequential extraction and the diffusive gradients in thin films (DGT) technique to assess environmental risks and study the remobilization of cobalt (Co) in sediments. The potential ecological risk index and risk assessment code results demonstrated that Co may pose a low environmental and ecological risk to the local aquatic environment. However, BCR sequential extraction showed that the sum of the F1, F2 and F3 fractions of Co still accounted for over 50% of the Co in the study areas, indicating that sediments may be a source of Co release. The DGT results showed an increasing trend for DGT-labile Co in deep sediments (−8 cm to −12 cm), and the calculated flux values ranged from 0.08 to 15.54 ng cm2·day−1, indicating that Co tends to transfer across the sediment-water interface at all sampling sites. Correlation analysis showed that F1–Co, F2–Co and F3–Co are the fractions readily captured by DGT and can be used for predicting Co remobilization in sediment. Sand mining activities contribute substantially to the release of Co from the F1 and F3 fractions as a result of strong stirring of sediments and introduction of oxygen into the sediments. The reductive dissolution of iron (Fe) and manganese (Mn) hydroxides or oxides causes the release of Co and Fe/Mn in the sediment, which leads to Co release from the reducible fraction. The above work suggests that sand mining in the Jialing River should be reasonably regulated to prohibit illegal sand mining activities.

Evaluation of Metformin Hydrochloride Tailoring Bilosomes as an Effective Transdermal Nanocarrier.

IntroductionMetformin hydrochloride (metformin HCL), a first-line drug treating diabetes type II, was known to cause severe gastritis, so seeking a non-oral dosage form was the new trend. Bilosomes are bilayer nano-vesicles of non-ionic surfactants embodying bile salts. In our study, bilosomes were investigated as an acceptable novel carrier for active targeting transdermal delivery of metformin HCL, circumventing its side effects.MethodsTwelve bilosome formulations were prepared with solvent evaporation method with slight modification according to a 31.22 full factorial design, and the optimized formulation was determined using Design -Expert 13 software (Stat-Ease, Inc., Minneapolis, Minnesota, USA) studying the effect of surfactant and bile salt types on the entrapment efficiency (EE), vesicle size (VS), polydispersity index (PDI), zeta potential (ZP), percentage of drug released within 24 h (R), and flux of drug permeated within 6 h (Jss) of vesicles. In addition, the optimized formulation was further evaluated to Fourier-transform infrared spectroscopy (FTIR), deformability index (DI), and transmission electron microscope (TEM) to ensure bilosomes formation, elasticity, and spherical shape, respectively.ResultsThe resulting vesicles publicized EE from 56.21% to 94.21%, VS from 183.64 to 701.8 nm, PDI values oscillating between 0.33 and 0.53, ZP (absolute value) from 29 to 44.2 mV, biphasic release profile within 24 h from 60.62 and up to 75.28%, and permeation flux enhancement (198.79–431.91 ng cm −2 h−1) in comparison with the non-formulated drug (154.26 ng cm −2 h−1). Optimized formulation was found to be F8 with EE = 79.49%, VS = 237.68 nm, ZP = 40.9 mV, PDI = 0.325, R = 75.28%, Jss = 333.45 ng cm−2 h−1 and DI = 6.5 with spherical self-closed non-aggregated vesicles and non-superimposed bands of its components in the FTIR.ConclusionOverall results showed that bilosome incorporation of metformin HCL improved permeation and offered a new nano-carrier for active transdermal delivery.

Effect of Stabilizer on Gold Leaching with Thiourea in Alkaline Solutions

The present work investigated the comparison of the effects of Na2SO3 and Na2SiO3 on thiourea stabilization, and a systematic study was undertaken to establish the effects of these stabilizers on the stability of alkaline thiourea, both qualitatively and quantitatively. The effects of these stabilizers on the activation energy of alkaline thiourea gold leaching was also studied. The results showed that sodium silicate was more suitable as a stabilizer in this system than sodium sulfite because the peak current of gold dissolution with sodium sulfite was higher than that with sodium silicate, but the inhibition of thiourea decomposition by the former was less obvious than that of sodium silicate in the cyclic voltammetry curve. The quartz crystal microbalance results showed that the quality decreased to about 100 ng cm2 in the presence of a stabilizer, while it increased to 300 ng cm2 in the absence of the stabilizer. It is inferred that gold can be dissolved by alkaline thiourea in the presence of a stabilizer, while it cannot without a stabilizer because of the decomposition of thiourea. This assumption was confirmed by atomic force microscopy measurements. The surface activation energy of Au dissolution decreased from 183.76 to 98.07 kJ/moL with the addition of sodium silicate, indicating that Au dissolution was promoted with the chemical.

Surface plasmon resonance sensing with thin films of palladium and platinum - quantitative and real-time analysis.

Surface plasmon resonance (SPR) is a highly useful technique in biology and is gradually becoming useful also for materials science. However, measurements to date have been performed almost exclusively on gold, which limits the possibility to probe chemical modifications of other metals. In this work we show that 20 nm Pd and Pt films work "fairly well" for quantitative SPR sensing of organic films despite the high light absorption. In the interval between total reflection and the SPR angle, high intensity changes occur when a film is formed on the surface. Fresnel models accurately describe the full angular spectra and our data analysis provides good resolution of surface coverage in air (a few ng cm-2). Overall, the Pd sensors behave quite similarly to 50 nm gold in terms of sensitivity and field extension, although the noise level in real-time measurements is ∼5 times higher. The Pt sensors exhibit a longer extension of the evanescent field and ∼10 times higher noise compared to gold. Yet, formation of organic layers a few nm in thickness can still be monitored in real-time. As a model system, we use thiolated poly(ethylene glycol) to make Pd and Pt protein repelling. Our findings show how SPR can be used for studying chemical modifications of two metals that are important in several contexts, for instance within heterogeneous catalysis. We emphasize the advantages of simple sample preparation and accurate quantitative analysis in the planar geometry by Fresnel models.