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1.
J Environ Manage ; 301: 113878, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34624577

RESUMO

The development of a pre-treatment plant for non-hazardous, solid mixed waste into a smart waste factory for future involves the introduction of real-time characterisation of waste streams by applying sensor technology. First, research has been conducted on the application of near-infrared spectroscopy for quality assurance of solid recovered fuels (SRF) produced by the pre-treatment plant. The method is based on statistical analyses, thereby requiring a comprehensive database of detailed waste data. To ensure high-precision measurements, data must be gathered at the level of individual particles and must cover a broad spectrum of different particle types. In a previous study, the fine-shredded SRF (<30 mm) was investigated. The scope of this study includes coarse-shredded SRF (30-80 mm) and mixed commercial waste (pre-shredded to a maximum of 500 mm), which is used as input for the waste pre-treatment plant. For a total of 2346 particles, the projected particle area, particle mass, and particle height were measured with average values of 11.5 cm2, 1.2 g and 10.4 mm, respectively, for the coarse-shredded SRF. Data results regarding pre-shredded waste input were 115 cm2 area, 16.7 g mass and 33.9 mm height. Combined with previous results, the dataset covers a range of particle areas from 15.7 mm2 to 16.7 dm2 and a range of particle mass from 1.6 mg to 882.5 g. Additionally, selected fuel parameters (heating value, chlorine content, and ash content) were measured using laboratory analysis of composite samples from coarse-shredded SRF and mixed commercial waste. The physico-chemical results of the present study confirmed previous results; however, the variance of values increased, and more outliers were identified. Despite the provision of particle data, the major goal of this study was to determine the correlation between the projected area and particle mass, which was calculated using the Spearman's correlation coefficient (SCC). The calculations resulted in an SCC of 0.58 for coarse-shredded SRF and an SCC of 0.22 for pre-shredded waste input. Although the SCC of SRF was sufficient for establishing a quality assurance system, the SCC of input waste must be substantially improved.


Assuntos
Calefação , Eliminação de Resíduos , Cloro , Resíduos Sólidos/análise
2.
J Pharm Biomed Anal ; 207: 114397, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34626940

RESUMO

A gas chromatography-mass spectrometric (GC-MS) method was developed for the qualitative and quantitative analysis of flavor chemicals in tobacco heating products (THPs), traditional tobacco products (TTPs) and their flavoring capsules. A total of 283 compounds were identified through non-target analysis, and the final 302 compounds were selected to develop an analytical method. The lower limits of detection (LOD) of analytes were 0.00074-12 mg/kg and their LOD range was wide depending on the presence or absence in the reference cigarette. The precision of the 302 compounds was less than 24.5%, and the accuracy ranged from 80.0% to 120%. A total of 190 flavors and 5 contaminants were determined in 21 THP, 10 TTP, 8 THP capsules and 11 TTP capsules. When comparing the total flavor content of flavors per cigarette, it was in the order of THP capsule> TTP capsule ≫ THP ≫ TTP. The correlations between the 53 cigarette products and 190 flavor chemicals were analyzed using PCA. It has been demonstrated that PCA results can be a useful tool in differentiating brands and manufacturers of tobacco products.


Assuntos
Sistemas Eletrônicos de Liberação de Nicotina , Produtos do Tabaco , Cápsulas , Aromatizantes , Calefação , Tabaco
3.
Food Chem ; 374: 131772, 2022 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-34896952

RESUMO

Bioactive substances are very important components of human milk (HM), especially for premature newborns. The effects of convection (CH) and microwave heating (MWH) at 62.5 and 66 °C, on the level of selected bioactive components of HM: lysozyme (LZ), lactoferrin (LF), secretory immunoglobulin A (sIgA), basal lipase (BL), cytokine TGF-2, vitamin C and total antioxidant capacity (TAC) was compared. Regardless of the used heating methods the TAC of HM, determined by TEAC and ORAC-FL assay, proved to be insensitive to temperature pasteurization, in contrary to BL. MWH in the conditions of 62.5 for 5 min and 66 °C for 3 min are ensuring microbiological safety with a higher retention of most of the tested active HM proteins compared to CH. Only in the case of LZ the MWH had a more degradative effect on its concentration. Controlled conditions of MWH preserve the bioactive components of the HM better than CH.


Assuntos
Convecção , Leite Humano , Calefação , Humanos , Recém-Nascido , Micro-Ondas , Pasteurização
4.
Bioresour Technol ; 344(Pt B): 126278, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34752893

RESUMO

Machine learning (ML) approach was applied for the prediction of biocrude yields (BY) and higher heating values (HHV) from hydrothermal liquefaction (HTL) of wet biomass and wastes using 17 input features from feedstock characteristics (biological and elemental properties) and operating conditions. Several novel ML algorithms were evaluated, based on 10-fold cross-validation, with 3 different sets of input features. An extreme gradient boosting (XGB) model proved to give the best prediction accuracy at nearly 0.9 R2 with normal root mean square error (NRMSE) of 0.16 for BY and about 0.87 R2 with NRMSE of about 0.04 for HHV. Temperature was found to be the most influential feature on the predictions for both BY and HHV. Meanwhile, feedstock characteristics contributed to the XGB model for more than 55%. Individual effects and interactions of most important features on the predictions were also exposed, leading to better understanding of the HTL system.


Assuntos
Biocombustíveis , Calefação , Biomassa , Aprendizado de Máquina , Temperatura , Água
5.
Spectrochim Acta A Mol Biomol Spectrosc ; 267(Pt 1): 120495, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34700156

RESUMO

In this work, we investigate the effects induced by the heating of acetonitrile-rich ice from 13 K to 350 K. Before the heating, the sample was irradiated at 13 K by broadband X-rays (6 eV to 2 keV), which trigger the production of new molecules, such as HCN, H2CCNH, CH4 and CH3NC (see Carvalho and Pilling, 2020) and also induced desorption of frozen species to gas-phase. New spectra were collected during heating to investigate whether new species, not present before at lower temperatures, appear due to thermal processing. New infrared bands were identified at temperatures around 120 K and 300 K, from which it was possible to notice the possible presence of HCN/CN radical, ammonia and C2N2. It was also verified that acetonitrile has a thermal desorption peak between 120 K and 200 K, which yields to the vanishing of acetonitrile within the sample for temperatures of 200 K and above. Some infrared features assigned before solely to acetonitrile remain for sample temperatures >200 K, which indicates the presence of blended species with similar infrared features. From analyzing those blended peaks, we also perceived the possible presence of aminoacetonitrile.


Assuntos
Meio Ambiente Extraterreno , Gelo , Acetonitrilas , Calefação , Raios X
6.
Sci Total Environ ; 806(Pt 3): 151287, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34736756

RESUMO

Catalytic fast pyrolysis experiments of low-density polyethylene (LDPE) over HZSM-5 were carried out by using infrared heating technology. The effects of heating rate (1-30 °C/s), pyrolysis temperature (450-650 °C), and mass ratio of catalyst to LDPE (0:100 to 50:100) on product distribution and oil composition in LDPE pyrolysis were investigated, and the fast pyrolysis mechanism was explored. The results indicated that a higher heating rate, namely 20 °C/s, can remarkably enhance the liquid oil yield (93.42%), but the oil is heavy due to about 90% high­carbon n-aliphatics. The addition of HZSM-5 performed an excellent effect on obtaining high-quality liquid oils, among which the total content of monocyclic aromatic hydrocarbons (MAHs) and iso-aliphatics obviously increase from 0.68% to 70.26%. The optimal HZSM-5/LDPE ratio of 10:100 was identified by considering the cost-effective factor. Furthermore, the lower catalytic temperature is favorable to the generation of light oil components, especially MAHs. The feasible generation paths were proposed, which mainly derived from the secondary reaction of the intermediate formed by initial chain cleavage including cyclization, aromatization, Diels-Alder reaction, as well as isomerization.


Assuntos
Polietileno , Pirólise , Biocombustíveis , Catálise , Calefação , Temperatura Alta
7.
Talanta ; 236: 122858, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34635242

RESUMO

Chemiluminescence signal amplification (CLSA) is of huge interest because of its sensitive detection in various applications such as food analysis, biomedical diagnosis and environmental monitoring. Due to this, there is a manifold attention to develop rapidly prototyped and miniaturized devices for CLSA. In this context, herein, a novel CLSA approach is demonstrated on a 3D printed microfluidic paper-based analytical device (µPADs), fabricated using Fused deposition modeling (FDM) printing technology. Influence of working temperature, ranging 30 °C-110 °C, on CL signal generation from well-established Luminol/Co+2 - H2O2 reaction was analyzed using a screen-printed flexible heater onto the 3D printed reaction platform. A smartphone-based capturing/detection system provided the amenability for a point-of-care testing system. For the first time, strong and stable CLSA was found with about 255% ± 5% increase in its signal intensity without using any additional external enhancers. The on-site working temperature was directly in proportional to the intensity of CL signal generated from Luminol/Co+2 - H2O2 reaction under optimum conditions, wherein the device had a wide linear range from 50 nM to 1 µM with a detection limit of 35 nM for H2O2 detection. The reliability of the developed amplification method was tested for practicability to detect the concentration of H2O2 in milk as real sample analysis. Overall, such CLSA mechanism in miniaturized µPADs will have strong potential for multiple CL based detection and monitoring application.


Assuntos
Luminescência , Smartphone , Calefação , Peróxido de Hidrogênio , Medições Luminescentes , Microfluídica , Peróxidos , Reprodutibilidade dos Testes
8.
Food Chem ; 370: 131371, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34656021

RESUMO

This study aimed to reveal the molecular mechanisms associated with off-flavor generation in sturgeon fillets treated by low temperature vacuum heating (LTVH). Label-free quantitative proteomics was used to identify 120 favor-related proteins, 27 proteins were screened as differentially expressed for bioinformatics analysis. 17 of KEGG pathways were identified. Particularly, proteins involved in proteasome and peroxisome were highly correlated with off-flavor formation. They were primarily implicated in the structures of proteins, including binding and proteasome pathways. The results indicated that the LTVH reduced the binding sites by down-regulating protease and superoxide dismutase expression. LTVH increased the myofibrillar protein and sulfhydryl content and decreased the total volatile basic nitrogen and thiobarbituric acid reactive substance, which confirmed that protein oxidation was related to off-flavor. This proteomics study provided new insights into the off-flavor of sturgeon with LTVH, and proposed potential link between biological processes and off-flavor formation.


Assuntos
Calefação , Proteômica , Federação Russa , Temperatura , Vácuo
9.
J Colloid Interface Sci ; 607(Pt 2): 1986-1992, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34695747

RESUMO

Freshwater crisis seriously challenges human survival and development, especially in arid regions. Solar-driven interfacial evaporation has recently received tremendous interest for collecting clean water, yet is only feasible in regions with available surface water. Atmospheric water harvesting is independent of surface water but requires high RH, additional energy input and complex equipment. Here, we demonstrate efficient water harvesting from desert soil in very dry regions (air RH < 10%, soil moisture content < 3%) via interfacial solar heating under natural sunlight. The water harvesting device, composed of merely a thin layer of activated carbon (for interfacial solar heating on soil surface), a commercially available polyethylene film (for vapor condensation and water transport) and a water container, could collect 1.13 kg of clean water per square meter of desert soil per day (8 h), i.e., 0.53 kg of clean water per kilogram of activated carbon per hour, under a solar flux of 0.26-0.55 kW m-2. Besides, the soil water harvesting system is very portable, low-cost and scalable. This work opens up a new sustainable approach for solving the freshwater crisis in arid and impoverished regions.


Assuntos
Luz Solar , Purificação da Água , Calefação , Humanos , Solo , Água
10.
Chemosphere ; 287(Pt 1): 132018, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34454221

RESUMO

Chemical oxidation and high-temperature heating have been widely used for the decontamination of soils polluted by hydrocarbons and the removal of soil organic matter. Chemical oxidation and high-temperature heating decreased the stability of soil colloids, but the difference in colloidal stability and aggregation behaviors of soil after chemical oxidation and high-temperature heating is not clear. In this study, taken black soil as an example, we tested the stability profiles of black soil colloids (BC), hydrogen peroxide (H2O2) treated black soil colloids (BC_H2O2), and 350 °C treated black soil colloids (BC_350 °C) in three salt solutions (NaCl, CaCl2, and Na2SO4) with different salt concentrations. The stability of soil colloids in salt solutions was in the order of BC > BC_350 °C > BC_H2O2. The salt concentrations at which three colloids started to be unstable were much lower for CaCl2 solution than those for NaCl and Na2SO4 solution. Salt concentrations that suspension started to be unstable were similar in NaCl and Na2SO4 solution for all the three colloids, but the colloidal stability profile in NaCl solution decreased faster than that in Na2SO4 solution when the suspension was unstable. The stability profiles of three colloids at the fast aggregation stage could be well fitted with the proposed exponential model, and model parameters (t0 and Smax) could reflect the stability behaviors of soil colloids in various salt solutions.


Assuntos
Peróxido de Hidrogênio , Solo , Coloides , Calefação , Temperatura
11.
Food Chem ; 369: 130958, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34479011

RESUMO

The aim of this study was to determine the influence of the microwave heating method (MWH) on selected determinants of the nutritional value of human milk (HM) and compare to the effect exerted by the standard convection heating (CH) method, including holder pasteurization (HoP). It was showed that using MWH under conditions assumed to ensure microbiological safety, changes in the level of the nutrients were not observed. In these conditions concentration of fatty acids (FAs), lipid peroxides (LP) and α-lactalbumin (α-La) were on a similar level as in raw milk, and furosine was not formed. MWH treatment of HM led to slight increase in the malonaldehyde (MDA) and protein carbonyls (PC) content. However, MDA content in HM as a result of MWH was lower than after application CH.


Assuntos
Calefação , Leite Humano , Convecção , Humanos , Micro-Ondas , Nutrientes , Pasteurização
12.
J Colloid Interface Sci ; 606(Pt 2): 971-982, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34487944

RESUMO

Remediation of crude oil spills is a great challenge owing to the poor mobility and high viscosity of crude oil. Herein, a porous polydimethylsiloxane@wood sponge/MXene (PDMS@WSM) with outstanding compressibility and hydrophobic/lipophilic ability was demonstrated as crude oil absorbent. The surface temperature of PDMS@WSM could quickly rise to 80 °C with a working voltage of 4 V and to 66 °C under simulated sunlight irradiation of 1.5 KW m-2, respectively. Due to the excellent Joule heating and photothermal conversion effect, the PDMS@WSM displayed maximum adsorption capacity of 11.2×105 g m-3 within 6 min. The PDMS@WSM showed preferable reusability and cycle stability because of its brilliant compressibility. Moreover, the oil-collecting device based on PDMS@WSM could continuously collect crude oil spills, achieving an active collection of 25 mL crude oil within 150 s. Therefore, the porous PDMS@WSM absorbent exhibited great potential for crude oil spills remediation, energy regulation, and desalination of hypersaline water.


Assuntos
Poluição por Petróleo , Petróleo , Calefação , Poluição por Petróleo/análise , Titânio , Madeira
13.
Sci Total Environ ; 803: 150083, 2022 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-34525679

RESUMO

Understanding the spatio-temporal heterogeneous effects of socioeconomic and meteorological factors on CO2 emissions from combinations of different district heating systems with "Coal-to-Gas" transition can contribute to the development of future low-carbon energy systems that are efficient and effective. This work downscales city-level CO2 emissions to a 3 × 3 km2 gridded level in northern China during 2012 to 2018. By employing the Geographically and Temporally Weighted Regression (GTWR) model, nighttime light (NTL) data are adopted as a proxy of the level of urbanization, and the Temperature-Humidity-Wind (THW) Index is used as a proxy of meteorological factors in the downscaling model. The results show that, for more than 85% of the cities, urbanization significantly enhances the CO2 emissions of district heating systems, while the THW Index shows negative impacts on CO2 emissions. Significant spatial and temporal heterogeneity exists. The grids with the highest CO2 emissions from coal-fired boilers (grids with annual variation >0.59 Gg CO2/year) are mainly located in nonurban areas of the two megacities Beijing and Tianjin and also in the capital cities of each province. Urbanization has larger effects on the CO2 emissions of natural gas-fired boilers than of coal-fired boilers and combined heat and power (CHP). The average growth rate of CO2 emissions of gas-fired boilers in the urban areas of the study regions was approximately 4.7 times that of nonurban areas. The spatio-temporal heterogeneous impacts of urbanization on CO2 emissions should therefore be considered in future discussions of clean heating policies and climate response strategies.


Assuntos
Dióxido de Carbono , Calefação , Dióxido de Carbono/análise , China , Carvão Mineral , Urbanização
14.
Sensors (Basel) ; 21(24)2021 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-34960257

RESUMO

The malfunctioning of the heating, ventilating, and air conditioning (HVAC) system is considered to be one of the main challenges in modern buildings. Due to the complexity of the building management system (BMS) with operational data input from a large number of sensors used in HVAC system, the faults can be very difficult to detect in the early stage. While numerous fault detection and diagnosis (FDD) methods with the use of statistical modeling and machine learning have revealed prominent results in recent years, early detection remains a challenging task since many current approaches are unfeasible for diagnosing some HVAC faults and have accuracy performance issues. In view of this, this study presents a novel hybrid FDD approach by combining random forest (RF) and support vector machine (SVM) classifiers for the application of FDD for the HVAC system. Experimental results demonstrate that our proposed hybrid random forest-support vector machine (HRF-SVM) outperforms other methods with higher prediction accuracy (98%), despite that the fault symptoms were insignificant. Furthermore, the proposed framework can reduce the significant number of sensors required and work well with the small number of faulty training data samples available in real-world applications.


Assuntos
Ar Condicionado , Máquina de Vetores de Suporte , Calefação , Aprendizado de Máquina , Modelos Estatísticos
15.
Artigo em Inglês | MEDLINE | ID: mdl-34769669

RESUMO

With the growth in China's economic GDP, energy consumption has increased year by year. The energy demand of rural residential buildings is 223 million tons of standard coal equivalent, accounting for 24% of the national energy demand. Therefore, an energy-saving design for rural residences is necessary. This research took the traditional residences in southern Shaanxi as the research object and combined the cooking methods in southern Shaanxi with solar heating, proposing a sunlight heating system with an additional firewall. The system is composed of a firewall system and a sunlight system. The combination of the two systems prolongs the heating time and makes up for the lack of intermittent heating. The firewall principle involves using the heat generated by cooking through the heat storage and heat release capacity of the wall, and using the principle of heat radiation and convection to increase the indoor temperature. Meanwhile, the principle of the additional sunlight room involves using the external facade of the building to establish an additional sunlight room, by absorbing the heat radiation of the sun and using the principle of heat transfer from the wall. The rapid loss of indoor hot air is avoided, the heating time is prolonged, and part of the heat is retained, thereby improving the heating efficiency. A model was established based on the typical residential model in southern Shaanxi, and the presence or absence of solar radiation on the wall was used as the research variable. Using ANSYS software to simulate the analysis, it is concluded that the firewall-sunlight system can extend the heating time and meet the continuous heating demand, and the heating effect is better than that of the firewall heating system alone. When the walls have solar radiation, the annual heat load reduction rate of the buildings under the new system is 20.21%. When the walls do not have solar radiation, the annual heat load reduction rate of the buildings under the new system is 8.56%.


Assuntos
Calefação , Energia Solar , Carvão Mineral , Habitação , Luz Solar
16.
Sensors (Basel) ; 21(21)2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34770334

RESUMO

This research was undertaken to perform and evaluate the temperature measurement in the ground utilized as an energy source with the goal to determine whether significant temperature variations occur in the subsurface during the heating season. The research infrastructure situated on our University campus was used to assess any variations. The observations were made at the so called "Small Research Polygon" that consists of 8 monitoring boreholes (Borehole Heat Exchangers) situated around a borehole used as an energy source. During the heating season, a series of monthly measurements are made in the monitoring boreholes using a distributed temperature system (DTS). Raman back-scattered light is analysed using Optical Frequency Time Domain Reflectometry (OTDR). Our results indicate that no noticeable changes in temperature occur during the heating season. We have observed an influence of long-term variations of the atmospheric conditions up to the depth of a conventional BHE (≈100 m). The resulting uncertainty in related design input parameters (ground thermal conductivity) was evaluated by using a heat production simulation. Production data during one heating season at our research facilities were evaluated against the design of the system. It is possible to construct smaller geothermal installations with appropriate BHE design that will have a minimal impact on the temperature of the surrounding rock mass and the system performance.


Assuntos
Fontes Geradoras de Energia , Calefação , Temperatura Alta , Humanos , Estações do Ano , Temperatura
17.
Sensors (Basel) ; 21(21)2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34770446

RESUMO

The mechanical loading frequency affects the functional properties of shape memory alloys (SMA). Thus, it is crucial to study its effect for the successful use of these materials in dynamic applications. Based on the superelastic cyclic behavior, this work presents an experimental methodology for the determination of the critical frequency of the self-heating of a NiTi Belleville conical spring. For this, cyclic compressive tests were carried out using a universal testing machine with loading frequencies ranging from 0.5 Hz to 10 Hz. The temperature variation during the cyclic tests was monitored using a micro thermocouple glued to the NiTi Belleville spring. Numerical simulations of the spring under quasi-static loadings were performed to assist the analysis. From the experimental methodology applied to the Belleville spring, a self-heating frequency of 1.7 Hz was identified. The self-heating is caused by the latent heat accumulation generated by successive cycles of stress-induced phase transformation in the material. At 2.0 Hz, an increase of 1.2 °C in the average temperature of the SMA device was verified between 1st and 128th superelastic cycles. At 10 Hz, the average temperature increase reached 7.9 °C and caused a 10% increase in the stiffness and 25% decrease in the viscous damping factor. Finally, predicted results of the force as a function of the loading frequency were obtained.


Assuntos
Calefação , Níquel , Ligas , Elasticidade , Teste de Materiais , Temperatura , Titânio
18.
J Acoust Soc Am ; 150(4): 3149, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34717455

RESUMO

Exposure to noise-or unwanted sound-is considered a major public health issue in the United States and internationally. Previous work has shown that even acute noise exposure can influence physiological response in humans and that individuals differ markedly in their susceptibility to noise. Recent research also suggests that specific acoustic properties of noise may have distinct effects on human physiological response. Much of the existing research on physiological response to noise consists of laboratory studies using very simple acoustic stimuli-like white noise or tone bursts-or field studies of longer-term workplace noise exposure that may neglect acoustic properties of the noise entirely. By using laboratory exposure to realistic heating, ventilation, and air conditioning (HVAC) noise, the current study explores the interaction between acoustic properties of annoying noise and individual response to working in occupational noise. This study assessed autonomic response to two acoustically distinct noises while participants performed cognitively demanding work. Results showed that the two HVAC noises affected physiological arousal in different ways. Individual differences in physiological response to noise as a function of noise sensitivity were also observed. Further research is necessary to link specific acoustic characteristics with differential physiological responses in humans.


Assuntos
Ar Condicionado , Ruído Ocupacional , Estimulação Acústica , Calefação , Humanos , Ventilação
19.
Anal Chem ; 93(44): 14701-14707, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34704432

RESUMO

In this paper, the first demonstration of direct ultratrace determination of lead in a single human hair by direct current-atmospheric pressure glow discharge-atomic emission spectrometry (DC-APGD-AES) coupled with electromagnetic heating vaporization (EMV) was described. Only the ultramicro mass of a human hair sample (about 0.15 mg, often a single human hair) was required during the analysis, and fast detection was implemented without tedious pretreatment processes, such as grinding and digestion. A limit of detection (LOD) of 30.8 µg kg-1 (4.8 pg) for Pb was obtained under optimized conditions, which was even equivalent to that of conventional LA-ICP-MS/ETV-ICP-MS/GFAAS. EMV-APGD-AES, meanwhile, can facilitate miniaturization and portability with low power and small size. The accuracy and practicality of the method were verified by the analysis of certified reference materials (CRMs) GBW09101b (human hair) and human hair samples from three volunteers. A simple, efficient, and low-cost method for detecting Pb in human hair has been developed.


Assuntos
Calefação , Chumbo , Pressão Atmosférica , Fenômenos Eletromagnéticos , Humanos , Análise Espectral , Volatilização
20.
Anal Chem ; 93(44): 14859-14868, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34705434

RESUMO

Airborne redox-active compounds (ARC) account for a substantial fraction of atmospheric aerosols and play a vital role in chemical processes that influence global climate and human and ecological health. With the exception of the determination of total organic carbon by the expensive total organic carbon (TOC) analyzer, there is currently no easy-to-use method to quantify ARC. Here, we designed a method to detect the concentration of ARC by using the thermal-induced reduction and colorimetric behaviors of gold nanoparticles (AuNPs), in which the humic substances (HS) was used as a standard model of ARC to calculate the HS-equivalent concentration of ARC. Distinguished from the conventional complex methods, e.g., TOC analysis, the proposed approach measured localized surface plasmon resonance absorption of AuNPs and the target ARC concentration can be either directly quantified by the absorption spectrometer or qualitatively evaluated by the naked eyes. By using the absorption spectrometer, a limit of detection of 0.005 ppm by our AuNP sensor was achieved. To validate this sensing technique, aerosol samples collected from Basel (suburban), Bern (urban), and Rigi mountain (rural and high-altitude) sites in Switzerland were further investigated through the TOC combustion method. The results thereby substantiated that our plasmonic absorption-based AuNP sensor upholds a great promise for fast, cost-efficient total ARC detection and air quality assessment.


Assuntos
Ouro , Nanopartículas Metálicas , Colorimetria , Calefação , Humanos , Oxirredução
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