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1.
ACS Nano ; 18(26): 16994-17006, 2024 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-38898819

RESUMEN

The desire to commercialize perovskite solar cells continues to mount, motivating the development of scalable production. Evaluations of the impact of open-air processing have revealed a variety of physical changes in the fabricated devices─with few changes having the capacity to be functionalized. Here, we highlight the beneficial role of ambient oxygen during the open-air thermal processing of metastable γ-CsPbI3-based perovskite thin films and devices. Physiochemical-sensitive probes elucidate oxygen intercalation and the formation of Pb-O bonds in the CsPbI3 crystal, entering via iodine vacancies at the surface, creating superoxide (O2-) through electron transfer reactions with molecular oxygen, which drives the formation of a zero-dimensional Cs4PbI6 capping layer during annealing (>330 °C). The chemical conversion permanently alters the film structure, helping to shield the subsurface perovskite from moisture and introduces lattice anchoring sites, stabilizing otherwise unstable γ-CsPbI3 films. This functional modification is demonstrated in γ-CsPbI2Br perovskite solar cells, boosting the operational stability and photoconversion efficiency of champion devices from 12.7 to 15.4% when annealed in dry air. Such findings prompt a reconsideration of glovebox-based perovskite solar cell research and establish a scenario where device fabrication can in fact greatly benefit from ambient oxygen.

2.
MethodsX ; 12: 102703, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38660039

RESUMEN

It is a fact that materials contract or expand by changing their temperature. In a certain temperature range, the distance between atoms changes linearly in some materials whereas it changes non-linearly in other materials. X-ray diffraction (XRD) is one of the popular techniques used for understanding the crystal structure of these materials. However, XRD is mostly carried in open air at room temperature or require very expensive high vacuum set-ups and expensive temperature controllers for low temperature studies. Here we propose a design of a variable temperature X-ray diffractometer that can operate in dual modes: heating and cooling in open air. The proposed diffractometer has been used for studying structural phase transition in chromium nitride thin films. The results demonstrated not only the effectiveness of our proposed setup but also its applicability in advancing our understanding of complex material behaviors.•A new design of a variable temperature X-ray diffractometer has been introduced in this paper, which can be used for acquiring XRD data while heating or cooling samples in open air.•As a proof of concept, the newly designed variable temperature X-ray diffractometer is used for studying structural phase transition in CrN thin films.

4.
Small ; 20(34): e2311472, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38651243

RESUMEN

Covalent organic frameworks (COFs), which have layered stacking structures, extended π-conjugation, and periodic frameworks have become a promising class of materials for a wide range of applications. However, their synthetic pathways frequently need high temperatures, enclosed systems under high pressures, an inert atmosphere, and extended reaction time, which restrict their practicality in real-world applications. Herein, the use of gamma irradiation is presented to synthesize highly crystalline COFs at room temperature under an open-air condition within a short time. This is demonstrated that there is no significant difference in crystallinity of COFs by gamma irradiation under air, N2 or Ar atmosphere conditions. Moreover, this approach can successfully fabricate COFs in the vessel with different degrees of transparency or even in a plastic container. Importantly, this strategy is applicable not only to imine linkage of COFs but also effective to the imide linkages of COFs. Most importantly, these COFs demonstrate improved crystallinity, surface area, and thermal stability in comparison to the corresponding materials synthesized via the solvothermal method. Finally, a COF synthesized through gamma irradiation exhibits remarkable photocatalytic activity in promoting the sacrificial hydrogen evolution from water, displaying a more catalytic efficiency compared with that of its solvothermal analogue.

5.
Front Plant Sci ; 15: 1340641, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38495367

RESUMEN

The cultivation of summer vegetables in open-air nutrient film technique (NFT) hydroponics is limited due to the elevated nutrient solution temperature (NST). In this regard, non-electric evaporative-cooling techniques were explored to maintain NST in open-air NFT hydroponics. Four cooling setups were employed by wrapping polyvinyl chloride (PVC) grow pipes with one and two layers of either wet or dry jute fabrics and attaching them with coiled aluminum pipe buried inside a) wet sand-filled brick tunnels (Cooling Setup I), b) two inverted and vertically stacked earthen pots (Cooling Setup II), c) two inverted and vertically stacked earthen pots externally wrapped with wet jute fabric (Wrapped Cooling Setup II), and d) an earthen pitcher wrapped with wet jute fabric (Cooling Setup III). Wrapping grow pipes with two layers of wet jute fabric reduced NST by 5°C as compared to exposed (naked) grow pipes. The double-layer jute fabric-wrapped grow pipes produced 182% more reduction in NST in comparison to single layer-wrapped grow pipes. Additionally, the installation of Wrapped Cooling Setup II and Cooling Setup III outperformed Cooling Setup I and Cooling Setup II through NST reduction of approximately 4°C in comparison to control. Interestingly, Cooling Setup III showed its effectiveness through NST reductions of 193%, 88%, and 23% during 11 a.m.-12 p.m. as compared to Cooling Setup I, Cooling Setup II, and Wrapped Cooling Setup II, respectively. In contrast, Wrapped Cooling Setup II caused NST reductions of 168%, 191%, and 18% during 2-3 p.m. in comparison to Cooling Setup I, Cooling Setup II, and Cooling Setup III, respectively. Thus, the double-layer jute fabric-wrapped grow pipes linked with Wrapped Cooling Setup II can ensure summer vegetable cultivation in open-air NFT hydroponics as indicated by the survival of five out of 12 vegetable plants till harvest by maintaining NST between 26°C and 28°C.

6.
ChemSusChem ; 17(10): e202301754, 2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38224525

RESUMEN

Alcohol groups and ß-O-4 (C-C) linkages are widespread in biomass feedstock that are abundant renewable resource for value-added chemicals. The development of sustainable protocols for direct oxidation or oxidative cleavage of feedstock materials in a controlled fashion, using open air as an oxidant is an intellectually stimulating task to produce industrially important value-added carbonyls. Further, the oxidative depolymerization of lignin into fine chemicals has evoked interest in recent times. Herein, we report the first example of a catalyst system that could activate molecular oxygen from atmospheric air for controlled oxidation and oxidative cleavage/depolymerization of feedstock materials such as alcohols, ß-O-4 (C-C) linkages and real lignin in water under open air conditions. The selectivity of carbonyl products is controlled by altering the pH between ~7.0 and ~12.0. The current strategy highlights the non-involvement of any external co-catalyst, oxidant, radical additives, and/or destructive organic solvents. The catalyst shows a wide substrate scope and eminent functional group tolerance. The upscaled multigram synthesis using an inexpensive catalyst and easily available oxidant evidences the practical utility of the developed protocol. A plausible mechanism has been proposed with the help of a few controlled experiments, and kinetic and computational studies.

7.
ACS Nano ; 17(23): 23794-23804, 2023 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-38009679

RESUMEN

Tin oxide (SnO2) is widely used as an inorganic electron transport layer (ETL) for rigid and flexible perovskite solar cells (PSCs). In this work, an extract of snail shell, the sodium salt of polyaspartic acid (S-PASP), a water-soluble polypeptide polymer, has been used to multifunctionally regulate SnO2 nanograins. S-PASP has a strong chelating and dispersing effect; thus, chemically adsorbed SnO2 can inhibit agglomeration. The S-PASP:SnO2 ETL also improved the extraction and transferability of carriers, reducing body defects and interfacial charge. Moreover, the S-PASP:SnO2 ETL promotes the vertical growth of the perovskite crystals due to its bottom-up morphology, wettability, and strain release, which is conducive to improving the photoelectric performance of the device. The optimized rigid device prepared under open-air conditions obtained a PCE of 20.92%. In addition, due to the stress compensation of the S-PASP long chain, which prevented the cracking and displacement of the ETL, the optimal PCE of the flexible device was 17.96%, and the initial efficiency was maintained at 82.8% after 100 bends. This work introduces a molecular doping mechanism for organic-inorganic hybrid electronics.

8.
Toxins (Basel) ; 15(10)2023 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-37888644

RESUMEN

Optimisation of solar drying to reduce fungal growth and Ochratoxin A (OTA) contamination is a crucial concern in raisin and currant production. Stochastic and deterministic analysis has been utilized to investigate environmental indicators and drying characteristics. The analysis was performed using two seedless grape varieties (Crimson-red and Thompson-white) that were artificially inoculated with Aspergillus carbonarius during open-air and tunnel drying. Air temperature (T) and relative humidity (RH) were measured and analysed during the drying experiment, along with grape surface temperature (Ts), and water activity (aw). The grape moisture content, fungal colonization, and OTA contamination were estimated, along with the water diffusivity (Deff) and peel resistance (rpeel) to water transfer. Monitoring the surface temperature of grapes is essential in the early detection of fungal growth and OTA contamination. As surface temperature should be carried out continuously, remote sensing protocols, such as infrared sensors, provide the most efficient means to achieve this. Furthermore, data collection and analysis could be conducted through the Internet of Things (IoT), thereby enabling effortless accessibility. The average Ts of the grapes was 6.5% higher in the tunnel than in the open-air drying. The difference between the RH of air and that in the plastic crates was 16.26-17.22%. In terms of CFU/mL, comparison between white and red grapes in the 2020 and 2021 experiments showed that the red grapes exhibited significantly higher values than the white grapes. Specifically, the values for red grapes were 4.3 in 2021 to 3.4 times in 2020 higher compared to the white grapes. On the basis of the conducted analysis, it was concluded that tunnel drying provided some advantages over open-air drying, provided that hygienic and managerial requirements are met.


Asunto(s)
Internet de las Cosas , Ocratoxinas , Vitis , Vitis/microbiología , Ocratoxinas/análisis , Agua
9.
Materials (Basel) ; 16(19)2023 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-37834582

RESUMEN

In this study, we present a physical method for the fabrication of oriented nanowires composed of mixed metal oxides. Pulsed laser deposition carried out in the air under atmospheric pressure was used for the production of samples. Two sets of experiments were performed by applying nanosecond and picosecond laser ablation, respectively. The depositions were performed using the laser ablation of mixed targets from iron oxide and zinc oxide as the initial materials in different ratios. The experiments were carried out in a magnetic field, which allowed us to control the morphology of nanostructures. The structure, microstructure, morphology, and composition of the structures obtained were studied in relation to the sample composition and laser ablation regime applied. The morphological analysis revealed that the structure of the samples consisted mainly of nanowire-like features reaching tens of micrometers in length. These nanowires were composed of nanoparticles and oriented predominantly in parallel to magnetic field lines. Nanoparticles produced using ps ablation were, on average, smaller than those obtained by ns ablation of the same target. Using ablation with ps laser pulses, we were able to produce new composite materials or materials containing unstable phases.

10.
Bioengineering (Basel) ; 10(8)2023 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-37627823

RESUMEN

This work demonstrated the feasibility of an industrial-scale aerated static pile composting system for treating one of the common biowastes-soybean curd residue. The mixing ratios of the feedstock were optimized to achieve a carbon-nitrogen ratio and a moisture level in the ranges of 25-35 and 60-70%, respectively. This open-air composting system required 6-7 months to obtain a mature compost. Solvita and seed germination tests further confirmed the maturity of the compost, with 25% compost extract concentration yielding the best germination index in the absence of phytotoxicity. The bacterial and fungal compositions of the compost piles were further examined with metagenomic analysis. Thermoactinomyces spp., Oceanobacillus spp., and Kroppenstedtia spp. were among the unique bacteria found, and Diutina rugosa, Thermomyces dupontii, and Candida taylorii were among the unique fungi found in the compost piles, suggesting the presence of good microorganisms for degrading the organic biowastes.

11.
Dialogues Health ; 3: 100148, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38515809

RESUMEN

Salt iodization is a positive exemplar of a sustainable public-private partnership in promoting better nutrition outcomes in many countries. However, the gains in the past decades are gradually being eroded, following laxity in policy implementation, monitoring and regulatory roles resulting in increasing access to non-labelled salt in the Nigerian market. This study was designed to evaluate the awareness, practices and perspectives on salt iodization and regulations among salt marketers and consumers in Ibadan, Oyo state. This mixed-method study was carried out in seven major markets across Ibadan metropolis. A three-stage sampling technique was used to select 77 salt users/clients, 103 salt vendors, 12 salt wholesalers and four regulators/producers. Interviewer-administered questionnaire was used to collect information on types/brands of salt, handling, retail practices, awareness, and salt purchase preference. Structured in-depth interview was used to elicit information on existing regulations, compliance level, and monitoring activities. Descriptive statistics were used to analyse quantitative data. Interviews were tape-recorded, transcribed verbatim and analyzed thematically. Males constituted 66.7%, 1.0% and 14.3% of respondents among wholesalers, retail vendors, and clients, respectively, with 100.0%, 58.3% and 84.4% having at least primary education. All wholesalers and 30.1% of retail vendors used shaded structure. About 67% of the wholesalers and 58.3% of the retailers sold branded salt. Clients' basis for the use of non-branded salt included cheapness and greater quantity (54.5%), higher intensiveness/saltiness and greater quantity (22.1%), and cheaper cost (18.2%). Only 3% of the consumers were aware of mandatory salt iodization, 3.9% were aware of guidelines on salt marketing and only 18.2% handled salt safely. Safe handling practices were found among all wholesalers and 44.7% of the retailers. Qualitative findings revealed the existence of regulation on the production, packing and marketing of salts in Nigeria, however, enforcement and monitoring at the market level is weak. The demand and use of industrial salt in food preparation remain widespread among consumers in Ibadan, Nigeria following limited awareness of salt iodization programme and its benefits. Regulations on salt marketing should be enforced at all levels and nutrition education on salt iodization should be intensified.

12.
Cureus ; 14(6): e26133, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35875284

RESUMEN

Outdoors, the risks of transmission of COVID-19 and many other respiratory infections are low. Several environmental factors are known to reduce the viability of viruses and other infectious pathogens in the air. They include variations in temperature, relative humidity, solar ultraviolet radiation, and dilution effects. But one agent that reduces the viability of both viruses and bacteria outdoors, the germicidal open-air factor (OAF), has not been properly recognized for decades. This is despite robust evidence that the OAF can influence both the survival of airborne pathogens and the course of infections. The germicidal effects of outdoor air were widely exploited during the late 19th and early 20th centuries. Firstly, in the treatment of tuberculosis patients who underwent 'open-air therapy' in sanatoria; and secondly by military surgeons during the First World War. They used the same open-air regimen in specially designed hospital wards to disinfect and heal severe wounds among injured soldiers. It was also used on influenza patients during the 1918-19 pandemic. Later, in the 1950s, open-air disinfection and treatment of burns were proposed in the event of nuclear warfare. During the 1960s, the OAF briefly returned to prominence when biodefence scientists conducted experiments proving that open air has a potent germicidal effect. When this work ended in the 1970s, interest in the OAF again fell away, and it remains largely ignored. The COVID-19 pandemic has revived interest in understanding the transmission dynamics and survival of viruses in the air. The pandemic has also stimulated research in the science and practice of improved ventilation to control respiratory infections. Such work is incomplete without an appreciation of the inactivation of viruses and other pathogens by the OAF, but this needs further investigation as a matter of urgency. Research to better understand the conditions under which the OAF can be preserved indoors is urgently needed. We need to review building design with better regard to infection control and patient recovery. But we need to act without delay, as there is already sufficient evidence to show that public health generally would improve if more emphasis was placed on increased exposure to outdoor air.

13.
Artículo en Inglés | MEDLINE | ID: mdl-35329090

RESUMEN

Dry fruits and nuts are nutritious foods with several health-promoting properties. However, they are prone to contamination with aflatoxins at all stages of production and storage. The present study aimed to determine the natural occurrence of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2), and total aflatoxins (AFT) in dates, pistachios, and walnuts collected from four districts of South Punjab (Pakistan), and to assess the associated health risks as estimated by dietary exposure and the Margin of Exposure (MoE) determinations. The contents of AFB1 and AFT in these food products were monitored during storage under three different conditions (open-air, hermetically closed jars, and refrigeration at 4 °C) to determine the most efficient conditions in preventing aflatoxin accumulation. HPLC-fluorescence analysis of 60 samples of these products for aflatoxin contamination showed that 52 (86.7%) samples were contaminated at different levels, with a maximum of 24.2 ng/g. The overall (all samples) mean concentrations of AFB1, AFB2, AFG1, AFG2, and AFT were 3.39 ± 2.96, 1.39 ± 1.68, 1.63 ± 1.48. 1.12 ± 1.23, and 7.54 ± 6.68, respectively. The Estimated Daily Intake (EDI) and MoE of aflatoxins through the consumption of the products ranged from 0.06 ng/kg bw/day to 2.0 ng/kg bw/day and from 84.84 to 2857.13, respectively, indicating that consumers are at high health risk. Significant differences were recorded between aflatoxin levels in the samples stored under different storage conditions, with storage under refrigeration (4 °C) being the most effective in controlling aflatoxin accumulation, although storage in closed jars was also efficient and offers a more flexible alternative to retailers. The findings of the study urge official authorities of Pakistan to implement appropriate regulatory and control measures and surveillance program to alleviate the potential public health risks associated with the consumption of dry fruits and nuts in the scope of their increased consumption.


Asunto(s)
Aflatoxinas , Frutas , Aflatoxina B1/análisis , Aflatoxinas/análisis , Cromatografía Líquida de Alta Presión , Contaminación de Alimentos/análisis , Frutas/química , Pakistán , Prevalencia
14.
ACS Appl Mater Interfaces ; 14(6): 8527-8536, 2022 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-35108489

RESUMEN

Strontium titanate (STO) is a well-known oxide used in a wide variety of applications due to its excellent stability and optoelectronic properties. However, its integration in photoelectrocatalytic devices is limited by the lack of fast and scalable methods to produce robust films at a low temperature and atmospheric pressure. Herein, we report an atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) approach for the synthesis of STO crystalline films and their applications for photoelectrochemical solar energy conversion. The film crystallinity, which plays a determinant role in the photoelectrochemical performance, was linked to the selected strontium precursor and injection method. Through thermal stability studies of the precursors [Sr(dpm), Sr(ipo), Sr(acac), and Ti(ipo)] and analysis of the solution droplet size, it was demonstrated that the closer thermal decomposition behavior and superior miscibility of the Sr(dpm) and Ti(ipo) precursors led to more homogeneous and crystalline films with the highest photoelectrochemical performance (16.5 µA cm-2 at 1.23 V vs RHE under 100 mW cm-2), which can be further improved by a factor of 3.4 using thermal annealing at 500 °C. Evidence of the impact of a strontium precursor on the properties of STO films is provided through thermogravimetric analysis, X-ray diffraction, energy-dispersive system, UV-vis, X-ray photoelectron spectroscopy, HIM-SIMS, and photoelectrochemical analysis.

15.
Agric Food Secur ; 11(1): 17, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35194514

RESUMEN

BACKGROUND: Household dietary diversity in Rwanda remains low and significantly contributes to the double burden of malnutrition. Rwanda has one of the highest under five stunting rates globally, and malnutrition remains one of the most pressing public health issues; therefore, factors that shape food and nutrition security are of utmost concern. Globally, the variety of foods available in open-air markets has been shown to affect dietary diversity. Furthermore, the consumption of indigenous foods can contribute to a diverse diet and improve nutrition status. At present, there are limited data on foods available for purchase in open-air markets in Africa. Therefore, this study was designed to provide data on food availability in the largest open-air markets of Rwanda's most populated city, Kigali, and to highlight which foods indigenous to Africa can be purchased. METHODS: All consumables were inventoried between October and December of 2020 in three open-air markets of Kigali, the capital city of Rwanda. Consumables were organized by the site of domestication and the nutritional contents of some African indigenous crops were compared to similar non-indigenous items. RESULTS: A variety of raw and processed consumables was available in the open-air markets inventoried; however, only 25.8% of available species are indigenous to Africa. All Rwanda's staples, including sweet potatoes, plantains, beans, maize, banana, and cassava, are endemic to other continents. Indigenous plant species, which are often drought-resistant and more nutritious, for example, Africa's pineapple fruits (Myrianthus holstii), could not be purchased in Kigali's open-air markets. Pineapple fruits are richer in iron, vitamin C, protein, and vitamin A than banana, which is the most consumed fruit in Rwanda. CONCLUSIONS: Given rapid population growth, limited arable land, and erratic climate patterns, policies to conserve and promote indigenous species, especially those already adapted to harsh environmental conditions, should be enacted in Rwanda. The cultivation of native vegetables and fruits in home gardens, and the conservation of edible wild species, can improve dietary diversity and enhance food and nutrition security across the entire country.

16.
Polymers (Basel) ; 13(12)2021 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-34200744

RESUMEN

In biomaterials and biotechnology, coatings loaded with bioactive agents are used to trigger biological responses by acting as drug release platforms and modulating surface properties. In this work, direct deposition of poly(acrylic acid) coatings containing various agents, such as dyes, fluorescent molecules, was achieved by aerosol-assisted open-air plasma. Using an original precursors injection strategy, an acrylic acid aerosol was loaded with an aqueous aerosol and deposited on silicon wafers. Results clearly showed that agents dissolved in the aqueous aerosol were successfully entrapped in the final coating. The effect of aerosols concentration, flow rate, and treatment time, on the coating morphology and the amount of entrapped agents, was also investigated. It was demonstrated that this process has the potential to entrap a tunable amount of any sensible water-soluble agent without altering its activity. To the best of our knowledge, this is the first time that the loading of an aqueous aerosol in coatings deposited by plasma from a liquid aerosol precursor is reported. This innovative approach complements plasma deposition of coatings loaded with bioactive agents from aqueous aerosols with the use of non-volatile liquid precursors.

17.
Toxins (Basel) ; 13(6)2021 06 03.
Artículo en Inglés | MEDLINE | ID: mdl-34205222

RESUMEN

Drying optimization, to mitigate fungal growth and Ochratoxin A (OTA) contamination is a key topic for raisin and currant production. Specific indicators of environmental conditions and drying properties were analyzed using two seedless grape varieties (Crimson-red and Thompson-white), artificially inoculated with Aspergillus carbonarius under open air and tunnel drying. The air temperature (T), relative humidity, grape surface temperature (Ts) and water activity throughout the drying experiment, the grapes' moisture content and the fungal colonization and OTA contamination during the drying process and their interactions were recorded and critically analyzed. Drying properties such as the water diffusivity (Deff) and peel resistance to water transfer were estimated. The grapes Ts was 5-7 °C higher in tunnel vs. open air-drying; the infected grapes had higher maximum Ts vs. the control (around 4-6 °C). OTA contamination was higher in tunnel vs. open air-dried grapes, but fungal colonies showed the opposite trend. The Deff was higher in tunnel than in the open air-drying by 54%; the infected grapes had more than 70% higher Deff than the control, differences explained by factors affecting the water transport. This study highlighted CFU and OTA indicators that affect the water availability between red and white grapes during open air and tunnel drying, estimated by the Deff and peel resistance. This raises new issues for future research.


Asunto(s)
Agricultura/métodos , Desecación/métodos , Contaminación de Alimentos/prevención & control , Frutas/química , Frutas/microbiología , Ocratoxinas/análisis , Vitis/química , Vitis/microbiología , Aspergillus , Contaminación de Alimentos/análisis , Humedad , Enfermedades de las Plantas , Luz Solar , Temperatura
18.
Arch Microbiol ; 203(7): 4041-4049, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34046704

RESUMEN

The SARS-CoV-2 pandemic has revived the debate about the routes of virus transmission and their likelihoods. It is of utmost importance to assess the risks of contamination of susceptible people by infectious individuals and to evaluate the level of SARS-CoV-2 and other respiratory viruses transmission in the community. Most countries have imposed non-pharmaceutical measures to contain SARS-CoV-2 transmission, including physical distancing and mask wearing. Here we evaluated the spreading of viruses in open air using harmless Escherichia coli bacteriophages as a surrogate. Phages were sprayed towards Petri dishes seeded with bacteria at different lengths and angles. Our results showed that the transmission rate decreased exponentially with distance. The highest recorded transmission rate was [Formula: see text] PFU/plate when phages were sprayed from a 1 m distance, suggesting that the probability of transmission of a single virus at a 1 m distance is 1:100,000.


Asunto(s)
Microbiología del Aire , Bacteriófagos , COVID-19 , COVID-19/transmisión , Humanos , Pandemias , SARS-CoV-2
19.
Mikrochim Acta ; 188(5): 172, 2021 04 23.
Artículo en Inglés | MEDLINE | ID: mdl-33893562

RESUMEN

Graphene oxide (GO)-functionalized pencil lead fiber was prepared for the first time by in situ oxidation and exfoliation of graphite contained in pencil lead fiber to porous graphene oxide structure via a one-step solvent-free dielectric barrier discharge (DBD) microplasma treatment. This new fiber was demonstrated as a highly efficient and low-cost solid-phase microextraction (SPME) fiber for the determination of toxic metal ions. The fiber extraction performance was evaluated by using cadmium as a model analyte in a direct immersing SPME mode. Unlike most commercially available and other lab-built fibers, the preparation of the graphene oxidized pencil lead fiber is environmentally friendly, low cost, and non-toxic without using any organic solvents. The fiber is robust due to its coating-free configuration. Furthermore, high extraction efficiency and high sensitivity for cadmium can be obtained due to the abundant oxygen-containing functional groups on the surface of the novel fiber. After extraction, the cadmium adsorbed on the fiber was desorbed to 150-µL solution. Graphite furnace atomic absorption spectrometry (GF-AAS) with low sample consumption was used to determine cadmium. The calibration curve for cadmium ions was linear in a range 0.04-0.26 µg L-1 with a detection limit of 0.005 µg L-1. A relative standard deviation (RSD, n = 5) of 2.1% was obtained at 0.1 µg L-1 of cadmium. The sensitivity enhancement factor (EF) value of the proposed SPME method was 25. The SPME fiber was successfully applied to determine cadmium in tap water, river water, and pond water with spike recoveries ranging from 94 to 105%. Pipe network water samples were also analyzed to evaluate the cadmium release to drinking water due to the corrosion of tubes.

20.
Environ Sci Pollut Res Int ; 28(34): 47182-47195, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33890211

RESUMEN

A large amount of dust particles produced by the wind in an open-air pile is one of the important reasons for air pollution. Studying the law of dust diffusion in local areas is of great significance for the atmospheric particulate control. In this study, a pile of sodium carbonate in a large open-air pile in Weifang, China, is regarded as the research object. The dispersion characteristics of dust particles around the pile under the action of unidirectional wind are studied through wind tunnel test and numerical simulation. The complex atmospheric environment is simplified as unidirectional wind, and the influence of different wind speeds on the dispersion of particles with diverse sizes in the pile is studied. Although a large gap exists between the assumption and the real atmospheric environment, this study provides a reference for the evaluation of the pollution scope of blowing dust and prevention and control of pollution. Results show that a high-concentration range of the dust exists near the pile behind the wind direction and may continue to spread to the height due to the influence of a whirlpool, and the dispersion distance and width can increase with the increase in wind speed. The increase in particle diameter increases the kinetic energy loss of particles for the fluid. Under the same starting speed, the dispersion distance of dust decreases with the increase in particle diameter. With the increase in particle diameter, the dust concentration distribution presents the trend of interior hollowing and high-concentration area fragmenting.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , China , Difusión , Polvo/análisis , Monitoreo del Ambiente , Tamaño de la Partícula
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