Rapid Release of Halocarbons from Saline Water by Iron-Based Photochemistry.

Methyl halides play important roles in stratospheric ozone depletion, but their formation mechanisms are not well defined. This study demonstrated that iron-based photochemistry significantly enhanced alkyl halide production by promoting the reaction of the representative monomer of lignin with halide ions in saline water under solar light irradiation. The methyl chloride (CH3Cl) emission from the light/Fe(III) process was 2 orders of magnitude higher than dark treatment and in the absence of iron. In addition, bromide and iodide showed better reactivity in the formation of the corresponding methyl bromide (CH3Br) and methyl iodide (CH3I). Alkyl halides identified from seawater, brackish water, and salt pan water under sunlight irradiation were positively correlated with the Fe(III) concentrations, indicating that iron-based photochemistry is ubiquitous. This work suggested that the photoinduced formation of methyl radical and redox cycling of iron triggered by the Fenton-like reaction are responsible for the enhanced release of alkyl halides. This study represents an abiotic formation pathway of alkyl halides, which accounts for a portion of the unidentified sources of halocarbons in the ocean.

A survey of epidemic management data models.

The COVID-19 epidemic has demonstrated the important role that data plays in the response to and management of public health emergencies. It has also heightened awareness of the role that ontologies play in the design of semantically precise data models that improve data interoperability among stakeholders. This paper surveys vocabularies and ontologies relevant to the task of achieving epidemic-related data interoperability. The paper first reviews 16 vocabularies and ontologies with respect to the use cases. Next it identifies patterns of knowledge that are common across multiple vocabularies and ontologies, followed by an analysis of patterns that are missing, based on the use cases. Conclusions show that existing vocabularies and ontologies provide significant coverage of the concepts underlying epidemic use cases, but there remain gaps in the coverage. More work is required to cover missing but significant concepts.

[Pollution Characteristics and Sources of Water-soluble Ions in PM2.5 in Zhengzhou City].

In order to explore the pollution characteristics, seasonal variations, and sources of water-soluble inorganic ions (WSIIs) in PM2.5 in Zhengzhou, PM2.5 samples were seasonally collected from December 2020 to October 2021; then, combining gaseous pollutants (SO2, NO2, and O3) and meteorological parameters (temperature and relative humidity), nine WSIIs (NO3-, NH4+, SO42-, Ca2+, K+, Na+, Mg2+, F-, and Cl-) were analyzed. The results showed that the annual average concentration of the total water-soluble ions (TWSIIs) was (39.34±21.56) µg·m-3for the four seasons, showing obvious seasonal variations with the maximum value in winter and the minimum value in summer. Annual PM2.5 was slightly alkaline in Zhengzhou, and NH4+ most likely existed in the form of NH4NO3 and (NH4)2SO4. The average sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) were 0.35 and 0.19, respectively, indicating that SO42- and NO3- mainly derived from secondary formation. The main potential source regions of WSIIs obtained by the concentration weight trajectory (CWT) model showed temporal and spatial variations. The significant sources of WSIIs based on principal component analysis (PCA) were dust, secondary generation, combustion, and industrial activities, which were obviously influenced by wind direction and speed in Zhengzhou.

Fading-free Φ-OTDR evaluation based on the statistical analysis of phase hopping.

In phase-sensitive optical time domain reflectometry (Φ-OTDR), false phase peaks caused by interference fading have been observed experimentally; however, the statistical law has not yet been disclosed. In this work, after clarifying that the false phase peaks originate from the phase hopping of demodulated phase noise during the unwinding process, we define the phase hopping rate (PHR) to evaluate the degree of fading and study the quantitative relationship between the PHR and signal-to-noise ratio (SNR) of the measured signal through theoretical derivation and experimental verification. In addition, a moving rotated-vector-average (MRVA) method is proposed to suppress the fading and eliminate the false phase peaks. In the experiment, after MRVA processing with a 25 ns sliding window, the lowest SNR is pulled from 0.003 to 14.9, and the corresponding PHR is reduced from 0.237 to less than 0.0001, which is consistent with the theoretical analysis.

Syntheses, Crystal Structures, and Antibacterial Activity of New Tetranuclear Zinc(II) Complexes with Schiff Base Ligands.

Two new tetranuclear zinc(II) complexes, [Zn4(L1)2(µ2-η1:η1-CH3COO)4(µ1,1-N3)2] (1) and [Zn4(L2)4(CH3CH2OH)(H2O)] (2), where L1 and L2 are the deprotonated forms of 4-fluoro-2-((pyridin-2-ylmethylimino)methyl)phenol (HL1) and 4-fluoro-2-((2-(hydroxymethyl)phenylimino)methyl)phenol (H2L2), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy, and single crystal X-ray diffraction. X-ray crystal structural study indicated that the distances between the adjacent Zn atoms are 3.160(1)-3.353(1) Å in 1 and 3.005(1)-3.168(1) Å in 2. All zinc atoms in 1 are pentacoordinated in trigonal bipyramidal geometry, and those in 2 are in square pyramidal and octahedral geometry. The complexes and the Schiff bases were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.

Synthesis, Characterization and Crystal Structures of Zinc(II) and Cobalt(III) Complexes Derived from Tridentate NNO- and NON- Schiff Bases with Antibacterial Activities.

Two new polynuclear zinc complexes [Zn2Br2(L1)2] (1) and [Zn(µ1,5-dca)L2]n (2), and two new mononuclear cobalt(III) complexes [CoL1N3(Brsal)] (3) and [CoL2(HL2)] (4), where L1 = 5-bromo-2-(((2-dimethylamino)ethyl)imino)methyl)phenolate, L2 = 5-bromo-2-(((2-hydroxyethyl)imino)methyl)phenolate, dca = dicyanoamide, Brsal = 5-bromo-2-formylphenolate, have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, UV-Vis spectra, molar conductivity, and single crystal X-ray diffraction. X-ray analysis indicates that the Zn atoms in complex 1 are in distorted square pyramidal coordination, the Zn atoms in complex 2 are in distorted trigonal bipyramidal coordination, and the Co atoms in complexes 3 and 4 are in octahedral coordination. The molecules of the complexes are stacked through π···π interactions and hydrogen bonds. The complexes were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.

Hybrid aperiodic coding for SNR improvement in a BOTDA fiber sensor.

The measurement accuracy of a Brillouin optical time domain analysis (BOTDA) fiber sensor is determined by the signal-to-noise ratio (SNR) of the received sensing signal. Here, a new hybrid aperiodic coding method is proposed to improve the SNR. In the proposed method, two pre-discovered short seed aperiodic codes (SA-codes) are used to construct a new hybrid aperiodic code (HA-code) in a nested way. The HA-code inherits the good denoising capabilities of the two SA-codes and features a high coding gain. In the proof-of-concept experiment, a SNR improvement up to 8 dB is obtained, which improves the measurement certainty to 1.67 MHz over a 117.46 km sensing range under a spatial resolution of 2.6 m.

Frequency splicing code-based Brillouin optical time domain collider for fast dynamic measurement.

We propose a frequency splicing code-based Brillouin optical time domain collider (FSC-BOTDC) for fast dynamic sensing. By delicately designing the frequency splicing code (FSC), multiple collision modes with controllable characteristics are realized for probing multiple target areas with a high sampling rate. Moreover, the sensing system is simpler and more robust than the previous BOTDC. In the experiment, the FSC-BOTDC with 10-time enhanced sampling rate is implemented for single and multiple target areas measurements. Results demonstrate that tailorable measurements can be achieved by the tunable FSC. Furthermore, the FSC-BOTDC is executed to measure periodic mechanical vibrations over 7.9-km sensing range with the sampling rate of 625 Hz.

Distributed dynamic strain sensing in coherent Φ-OTDR with a pulse conversion algorithm.

In this Letter, a chirped-pulse conversion algorithm (CPCA) is proposed to convert a normal probe pulse into an equivalent chirped probe pulse by convolving a chirp factor on the received signal in coherent phase-sensitive optical time-domain reflectometry (Φ-OTDR). With this algorithm, the Rayleigh interference pattern (RIP) demodulation once applied to chirped-pulse Φ-OTDR can be adopted to quantify the dynamic strain in the traditional coherent Φ-OTDR. Since the equivalent chirped pulse is generated by digital processing, complex and costly chirp modulation is not required. The proposed scheme is capable of fully quantifying perturbations with spatial resolution of 4 m, a sensing range of 8 km, frequency response of 5 kHz, and strain resolution of 56pε/√Hz.

Hydrophobic deep eutectic solvents based membrane emulsification-assisted liquid-phase microextraction method for determination of pyrethroids in tea beverages.

Deep eutectic solvents (DESs) were used as an extractant for the determination of pyrethroids in environmental water and tea beverage samples. Three different acids were chosen as hydrogen bond donors for preparation of DESs, and decanoic acid was optimal because of its high recovery. Factors affecting relative recovery were optimized individually, including salt addition, surfactant addition, extraction temperature, DES amount, and sample volume etc. Under the optimized experimental conditions, the relative recovery of pyrethroids was from 89.3% to 97.7%, with relative standard deviation (RSD) values ranging from 1.75% to 2.73%. The linear correlation coefficient ranged from 0.9981 to 0.9992, and the linear range was between 1.9 and 500 µg/L. Based on a signal-to-noise ratio (S/N) of 3:1, the limit of detection (LOD) values were 0.56 to 1.24 µg/L. The enrichment factor ranged from 92 to 105. In conclusion, good extraction efficiency was achieved in tea beverage samples under the optimized conditions.

Enhanced range of the dynamic strain measurement in phase-sensitive OTDR with tunable sensitivity.

Phase-sensitive optical time domain reflectometry (Φ-OTDR) realizes quantitative measurement of the dynamic strain employing phase demodulation. Unfortunately, it is difficult to measure the large dynamic strain with the conventional Φ-OTDR due to the restriction of the unwrapping algorithm. In this work, an approach based on two-wavelength probe is proposed and demonstrated to improve the measurable range of the dynamic strain in Φ-OTDR. By utilizing the difference between the two phases acquiring with two different lasers, the large dynamic strain can be recovered. In experiments, dynamic strains with peak values from 10.32 uɛ to 24.08 uɛ are retrieved accurately, which cannot be recovered with the conventional Φ-OTDR. Moreover, the tunable sensitivity is also demonstrated through adjusting the wavelengths of the probe. With the increment of the wavelength interval from 9.06 nm to 23.06 nm, the normalized sensitivity increases from 0.4 to 1 accordingly. That agrees well with the theoretical prediction. Foreseeably, the proposed method will extend the scope of application fields for Φ-OTDR, which requires large dynamic strain recognition.

Extraction of benzoylurea pesticides from tea and fruit juices using deep eutectic solvents.

In this study, low-density deep eutectic solvent combined with dispersive liquid-liquid microextraction was applied to the extraction of five benzoylurea insecticides (BUs, including diflubenzuron, triflumuron, hexaflumuron, flufenoxuron, and chlorfluazuron) from beverages. Then the extracted and concentrated samples were analyzed and detected using the high-performance liquid chromatography combined with an ultraviolet detector. The DESs were synthesized by [P14,6,6,6]Cl as hydrogen bond acceptor and tetradecyl alcohol as hydrogen bond donor, and then characterized by Fourier transform infrared spectroscopy. In the experiment, the key factors affecting the extraction efficiency were screened by Plackett-Burman design and optimized with the central composite design. The extraction recovery rates were 85.91-95.12%. The limits of detection and correlation coefficients of the method were 0.30-0.60 µg L-1 and 0.9992-0.9997. Finally, the method was applied to determine the BUs in four beverage samples, and satisfactory recoveries, within the range of 76.87-101.19% were achieved. The present method has the potential to be applied to the detection of BUs in aqueous samples.

Study on the adsorption mechanism of benzoylurea insecticides onto modified hyperbranched polysilicon materials.

Several hyperbranched polysilicon (HBPS) materials with different end group modifications were designed and synthesized and the structures were characterized. The modified HBPS polymers were applied to the adsorption of benzoylurea insecticides (BUs). The binding mode and binding energy between the HBPS and BUs were quantified and the results of an adsorption kinetics study and an adsorption thermodynamics experiment were verified by calculation and mutual verification. The adsorption mechanism of BUs onto HBPS was also discussed. The theoretical results show that the most effective way to combine the adsorbent and BUs is via hydrogen bonding when the end group is an amino group. Moreover, the most effective combination when the end group is ß-cyclodextrin is the interaction of the BUs with the interior of the cavity to form a host-guest coating. The theoretical results of other end group-modified HBPS materials were also obtained and verified by adsorption experiments. In this work, an experimental method for obtaining the binding mode by theoretical calculations and then verifying it according to adsorption experiments was established.

Genome survey, high-resolution genetic linkage map construction, growth-related quantitative trait locus (QTL) identification and gene location in Scylla paramamosain.

Scylla paramamosain is one of the most economically important crabs in China. In this study, the first genome survey sequencing of this crab was performed, and the results revealed that the estimated genome size was 1.21 Gb with high heterozygosity (1.3%). Then, RAD technology was used to construct a high-resolution linkage map for this species. A total of 24,444 single nucleotide polymorphism (SNP) makers were grouped into 47 linkage groups. The total length of the linkage groups was 3087.53 cM with a markers interval of 0.92 cM. With the aid of transcriptome and genome scaffold data, 4,271 markers were linked to genes, including several important growth-related genes such as transforming growth factor-beta regulator I, immune related-gene C-type lectin and ecdysone pathway gene broad-complex-like protein. Further, 442 markers, representing 279 QTLs, associated with 24 traits were identified, and of these markers, 78 were linked to genes. Some interesting genes, such as dedicator of cytokinesis protein 3, tenascin-X and DNA helicase MCM8, were believed to have important relationship with specific traits and merit further exploration. The results of this study will accelerate the genetic improvement and genome sequencing analysis of the mud crab.

Magnetic solid-phase extraction of benzoylurea insecticides in tea samples with Fe3 O4 -hyperbranched polyester magnetic composite as sorbent.

In this work, a method for the analysis of benzoylurea insecticides, including hexaflumuron, flufenoxuron, lufenuron and chlorfluazuron, in tea samples by high-performance liquid chromatography with Fe3 O4 -hyperbranched polyester nanocomposite as the adsorbent for magnetic solid-phase extraction was developed. The magnetic nanocomposite was prepared and characterized by infrared spectroscopy, vibrating sample magnetometry, and scanning electron microscopy. The as-prepared nanocomposite was used as a sorbent for the extraction and preconcentration of pesticide residues in tea samples. The extraction and desorption conditions, including mass ratios of raw materials, amount of sorbent, pH value, extraction time, and desorption time, were investigated. Under the final conditions chosen for the analysis, good linearity was obtained for all the tested compounds, with R2 values of at least 0.9979. The limits of detection were determined in the range of 0.15-0.3 µg/L. The recovery obtained from the analysis of tea samples with various spiked concentrations was between 90.7 and 98.4%, with relative standard deviations (n = 4) lower than 4.1%. Furthermore, the present approach was successfully applied to the quantitative determination of residues of benzoylurea insecticides in real samples.

Vortex-assisted deep eutectic solvent reversed-phase liquid-liquid microextraction of triazine herbicides in edible vegetable oils.

In this study, four triazine herbicides-namely, simazine, ametryn, prometryn and terbuthylazine-were separated and determined using high-performance liquid chromatography coupled with ultraviolet detector (HPLC-UVD). The deep eutectic solvent (DES) formed by tetrabutylammonium chloride ([N4444]Cl, TBA) and ethylene glycol (EG) was selected as the extraction solvent of vortex-assisted reversed-phase liquid-liquid microextraction (VA-RPLLME). The application of the hydrophilic DES expands the range of choice for LLME. The experimental parameters affecting the extraction recoveries, including the amount of the DES, the sample volume and the vortex time, were investigated and optimized by the design of experiments (DoE) methodology. A quadratic model, namely central composite face-centered (CCF) design featuring 20 runs was used instead of the conventional trial and error approach. Under optimum conditions, the limits of determination (LODs) of the method were 0.60-1.50 µg L-1. The enrichment factors for the analytes ranged from 27 to 31. The extraction recoveries were in the range of 84.1-104.9%, and the intra-day, inter-day and intermediate relative standard deviations (RSDs) were less than 8.4%. Finally, the method was applied for the determination of triazine herbicides in vegetable oil samples. The obtained recoveries were in the range of 60.1-107.2% and RSDs were lower than 8.1%. In general, VA-RPLLME can be complementary to the present available methods for the determination of triazine herbicides in vegetable oil samples.

Synthesis, Characterization, X-Ray Crystal Structures and Antibacterial Activities of Oxidovanadium(V) Complexes with Hydrazone and Hydroxamate Ligands.

Two new oxidovanadium(V) complexes, [VOL1L] (1) and [VOL2L]·CH3OH (2·CH3OH), where L1 and L2 are the dianionic form of N'-(3-bromo-2-hydroxybenzylidene)picolinohydrazide (H2L1) and 2-chloro-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (H2L2), respectively, and L is the monoanionic form of 2-hydroxybenzohydroxamic acid (HL), were prepared and characterized by elemental analysis, infrared and electronic spectroscopy. Structures of the complexes were further confirmed by single crystal X-ray determination. The V atoms in the complexes are in octahedral coordination. The hydrazone ligands coordinate to the V atoms through the phenolate O, imino N, and enolate O atoms. The hydroxamate ligand coordinates to the V atom through the carbonyl and hydroxy O atoms. The complexes show effective antibacterial activity against B. subtilis, S. aureus and E. coli. The presence of Cl substitute group in the complex may enhance the antibacterial activity.

Determination of four pyrethroid insecticides in water samples through membrane emulsification-assisted liquid-liquid microextraction based on solidification of floating organic droplets.

A novel membrane emulsification-assisted liquid-liquid microextraction method based on the solidification of floating organic drops was used to detect four pyrethroid pesticides (deltamethrin, etofenprox, fenpropathrin, and bifenthrin). In this method, [P44412]Br was used as a surfactant that could be removed from water via the addition of KPF6. The extraction solvent was separated after centrifugation and solidification on the water surface. The parameters affecting the recovery of the target compounds, including the surfactant amount, [P44412]Br-to-KPF6 molar ratio, addition of salt, extraction solvent volume, and temperature, were individually optimized and further analyzed through an orthogonal array design (OAD) experiment. The optimized conditions were based on the results of the OAD experiment and single-factor analysis. Using these experimental conditions, the recovery of the four pyrethroids ranged from 91.3% to 98.1% with relative standard deviation (RSD) values ranging from 1.7 to 2.2%. Good linearity was observed, with values from 0.9982 to 0.9997, and the linear range was between 1 and 500 µg/L (5-500 µg/L for fenpropathrin). The limit of detection (LOD) values based on a signal-to-noise ratio (S/N) of 3:1 were 0.37-0.75 µg/L. The enrichment factor ranged from 90 to 96. Therefore, this method is suitable for the determination of pyrethroid pesticides in environmental water samples.

Novel birefringence interrogation for Sagnac loop interferometer sensor with unlimited linear measurement range.

A novel demodulation method for Sagnac loop interferometer based sensor has been proposed and demonstrated, by unwrapping the phase changes with birefringence interrogation. A temperature sensor based on Sagnac loop interferometer has been used to verify the feasibility of the proposed method. Several tests with 40 °C temperature range have been accomplished with a great linearity of 0.9996 in full range. The proposed scheme is universal for all Sagnac loop interferometer based sensors and it has unlimited linear measurable range which overwhelming the conventional demodulation method with peak/dip tracing. Furthermore, the influence of the wavelength sampling interval and wavelength span on the demodulation error has been discussed in this work. The proposed interrogation method has a great significance for Sagnac loop interferometer sensor and it might greatly enhance the availability of this type of sensors in practical application.

Centrifuge-less dispersive liquid-liquid microextraction base on the solidification of switchable solvent for rapid on-site extraction of four pyrethroid insecticides in water samples.

An on-site dispersive liquid liquid microextraction base on the solidification of switchable solvent has been developed as a simple, rapid and eco-friendly sample extraction method for the fast determination of pyrethroid insecticides in aqueous samples using high-performance liquid chromatography with ultraviolet detection. In this extraction method, medium-chain saturated fatty acids (n≥10), which can rapidly solidify at low temperatures (<20°C), were investigated as switchable hydrophilic solvents. The fatty acids were converted into the hydrophilic form by adding sodium hydroxide. Microdroplets of the fatty acids were generated when injected into an acidic sample that had been pretreated by the addition of sulfuric acid. The formed cloudy solution was cooled to a low temperature to turn the fatty acids into a solid, which was then separated by filtration, thus avoiding the time-consuming step of centrifugation. The microextraction process was performed in a 10mL syringe and the pretreatment process could thus be finished in 5min. No external energy resources were required in this method, which makes it a potential method for on-site extraction. The optimal experimental parameters were as follows: 350µL of decanoic acid (1mol/L) was used as the extraction solvent, 150µL of sulfuric acid (2mol/L) was used to decrease the pH of the samples, no salt was added, and the temperature of the samples was in the range of 20-40°C. Finally, the sample was cooled in an ice bath for three minutes. Under these optimal conditions, good responses for four pyrethroid insecticides were obtained in the concentration ranges of 1-500µg/L, with coefficients of determination greater than 0.9993. The recoveries of the four pyrethroid insecticides ranged from 84.7 to 95.3%, with relative standard deviations ranging from 1.6 to 4.6%. The limits of detection based on a signal-to-noise ratio of 3 were in the range of 0.24-0.68µg/L, and the enrichment factors were in the range of 121-136. The results demonstrate that this method was successfully applied to determine pyrethroid insecticides in real water samples. No centrifugation or any special apparatus are required, make this a promising method for rapid field-sampling procedures.