In this work, we developed a simple, facile, and highly sensitive nanoparticle-based chemiluminescent (CL) sensor array for the discrimination of organophosphate and carbamate pesticides. This CL ...sensor array is based on simultaneous utilization of the triple-channel properties of the luminol-functionalized silver nanoparticle (Lum-AgNP) and H2O2 CL system containing CL intensity, the time for CL emissions to appear, and the time to reach the CL peak value, which are able to be measured via a single experiment. The triple-channel properties can be simultaneously altered after interaction with pesticides, producing distinct CL response patterns as "fingerprints" related to each specific pesticide, which was subjected to principal component analysis (PCA) to generate a clustering map. Using this sensor array, five organophosphate and carbamate pesticides, including dimethoate, dipterex, carbaryl, chlorpyrifos, and carbofuran, have been well-distinguished at a concentration of 24 μg/mL. A total of 20 unknown pesticide samples have been successfully identified with an accuracy of 95%. The simple strategy of this study is expected to promote the development of functionalized nanomaterial-based sensor arrays.
Abstract
Zeolitic imidazolate frameworks (ZIFs) are very useful as high-capacity iodine (I
2
) adsorbents. The adsorption performance is usually probed by measuring a statistical average property ...over an entire sample consisting of a large number of ZIF particles, leaving the interparticle heterogeneity information among individuals. Here we report a dark-field microscopy (DFM) method to visualize gaseous I
2
adsorption on single ZIF-90 particles in situ and in real time. The adsorption of I
2
is found to alter the scattering spectrum of ZIF-90 particles, inducing a distinct color change from bluewhite to yellow. According to correlating the adsorption amount of gaseous I
2
with the change of B value from DFM images, we quantitatively image the adsorption process and estimate the related kinetic parameters at the single particle level. Single particle measurements clarify the large particle-to-particle heterogeneity in adsorption reactivity and significant adsorption activity improvement of ZIF-90 after introduction of linker defects, which provides a microscopic understanding of the structure-activity relationship. We further demonstrate the capacity of this strategy for studying gaseous I
2
adsorption on single ZIF-91 particle as a derivative of ZIF-90 to illustrate the generality.
•A colorimetric sensor array for differentiating five organic antifreezes is successfully developed.•Five organic antifreezes have been successfully discriminated at a low concentration of 50 mM.•A ...high accuracy (100%) examination of 30 unknown samples is achieved.•The sensor array also performs well in real water sample.
We report a colorimetric nanoparticle array for discrimination of five organic antifreezes containing ethylene glycol (EG), formamide (FA), ethanol (EtOH), glycerin (Gly), and polyethylene glycol (PEG). Silver nanopartciles, gold nanoparticles, and Prussian blue nanoparticles are employed to be three sensing elements due to their unique optical absorption properties. The organic antifreezes can alleviate the aggregation of three nanoparticles after a freeze-thawing cycle. Based on the different freezing resistances of various antifreezes, the sensor array shows a unique colorimetric pattern of absorbance variations for each antifreeze, which is further analyzed by principal component analysis (PCA). The present sensor array has the capacity to differentiate antifreezes and their mixtures at a concentration as low as 50 mM. Moreover, the sensor array can also discriminate organic antifreezes in real water sample. Additionally, a high accuracy (100%) examination of 30 unknown samples is achieved.
Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development ...and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO42−) and nitrate (NO3−) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO42− deposition declined from 40.54 to 34.87 kg S ha−1 yr−1 but average NO3− deposition increased from 4.44 to 7.73 kg N ha−1 yr−1. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions.
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•Explore spatial and temporal dynamics of wet acid deposition during three decades in China.•Acid deposition has not deteriorated seriously in China with lower SO42− and higher NO3− deposition.•Area of severe acid deposition in southern China is shrinking with lower SO2 emissions.•Moderate acid deposition area is expanding in northern China because of higher levels of industry and transportation.•China's acid deposition is affected by energy consumption and regulated by rainfall.
This paper assesses the level of atmospheric wet acid deposition in China over three decades. Like most developing countries, China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. However, how and what it changed is still unknown for us. It is therefore vital to quantify its spatiotemporal variations and influencing factors, in order to perform more effective control measures.
•A formic acid-assisted photolysis of UO22+ initiated chromogenic reaction is fabricated for colorimetric detection of UO22+.•This colorimetric assay realizes visualization of UO22+ at a ...concentration of 0.5 μM.•It possesses excellent selectivity over common inorganic ions with even 50-fold higher concentration than UO22+.
Current strategies for visual detection of uranyl ion (UO22+) often require DNAzymes and organophosphorus receptors as well as various nanomaterials that may affect the selectivity, sensitivity, and accuracy in a complicated environment. Here, we circumvent these drawbacks by introducing a formic acid (FA)-assisted photolysis of UO22+ initiated chromogenic reaction for specific recognition element-free colorimetric detection of UO22+. The colorless 2, 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) is oxidized by the superoxide anion from the photolysis of UO22+ to generate green ABTS radical, which enables the determination of UO22+ at a concentration of 0.5 μM with the naked eye. The present colorimetric assay is able to determine concentrations of UO22+ from 0.1 to 100 μM, with a limit of detection as low as 0.01 μM. Impressively, the specific recognition element-free colorimetric assay possesses excellent selectivity over common inoganic ions with even 50-fold higher concentration than UO22+. In addition to good sensitivity and selectivity, this colorimetric assay is also capable of determining UO22+ in natural water samples with satisfactory recoveries.
Sequentially timed all-optical mapping photography is one of the main emerging ultra-fast detection technologies that can be widely applicable to ultra-fast detection at the picosecond level in ...fields such as materials and life sciences. We propose a new optical structure for an all-optical spatial mapping module that can control the optical field of two-dimensional imaging while improving spectral resolution and detector sensor utilization. The model of optical parameters based on geometrical optics theory for the given structure has been established, and the theoretical analysis of the inter-frame energy crosstalk caused by incident beam spot width, chromatic aberration, and main errors of the periscope array has been conducted. The optical design of the two-dimensional (2D) all-optical spatial mapping module was finally completed using ZEMAX OpticStudio 2018 software. The results show that our optical module can realize targets of 16 frames and 1.25 nm spectral resolution.
We demonstrate a selective and sensitive method for determination of creatinine using citrate-stabilized gold nanoparticles (AuNPs) as a colorimetric probe. It is based on a direct cross-linking ...reaction that occurs between creatinine and AuNPs that causes aggregation of AuNPs and results in a color change from wine red to blue. The absorption peak is shifted from 520 to 670 nm. Under the optimized conditions, the shift in the absorption peak is related the logarithm of the creatinine concentration in the 0.1 to 20 mM range, and the instrumental detection limit (LOD) is 80 μM. This LOD is about one order of magnitude better than that that of the Jaffé method (720 μM). The assay displays good selectivity over interfering substances including various inorganic ions, organic small compounds, proteins, and biothiols. It was successfully employed to the determination of creatinine in spiked human urine.
Graphical Abstract
The colorimetric assay for creatinine uses citrate-stabilized gold nanoparticles (AuNPs) and a direct cross-linking reaction that occurs between creatinine and AuNPs that causes aggregation of AuNPs and results in a color change from wine red to blue.
•It is first time to employ MnO2 nanosheets to be colorimetric probes in analysis.•The developed assay for hydrazine did not complex labeling procedure and the related chemical reaction could be ...accomplished within 1min, thereby simplifying the experimental operation.•As opposed to approaches based on the aggregation of gold nanoparticles for the detection of hydrazine, the developed assay utilizes the color change originating from alterations in the composition of nanomaterials in response to the analyte.
A novel, label-free, and low-cost colorimetric assay is developed for the detection of hydrazine with high-selectivity and excellent sensitivity using MnO2 nanosheets as probes. It is first time demonstrated that MnO2 nanosheets can be used as colorimetric probes for environmental analysis. In the absence of hydrazine, MnO2 nanosheets exhibit a strong ultraviolet–visible (UV–vis) absorption peak at 370nm due to the d-d transition. Once hydrazine is introduced, MnO2 nanosheets will be reduced to Mn(OH)2 nanoparticles, and the absorbance at 370nm decreases remarkably. In this case, a distinct color change from yellow to colorless can be observed, which is dependent on the concentration of hydrazine. The signal change can allow colorimetric detection of hydrazine. The assay offers a good linear range from 0.5μM to 20μM and a detection limit of 0.4μM for hydrazine. The lowest detection concentration by the naked eye is as low as 11μM. Additionally, the developed assay was successfully applied for the colorimetric detection of hydrazine in environmental water samples.
Two new species of the genus
,
and
, are described from the southwest China. Photographs of the adults and the genitalia are provided. Keys to the species of the genus based on the male and female ...genitalia are given.
In China, six species of Statherotmantis Diakonoff, 1973 were previously recorded. In the present study, four other species were recognized using morphology and DNA barcording analysis. Among these, ...three of which, S. miniscula sp. n., S. calva sp. n., and S. longiuscula sp. n., are described as new. In addition, one species, S. laetana Kuznetzov, 1988, is a new record for China. Adults and genitalia are illustrated, and keys to identify the Chinese species of Statherotmantis are provided.
In the present study, three new species and one new record are recognized using morphology and DNA barcording analysis.
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