Laboratory and field evaluation of a low-cost optical particle sizer.

Low-cost sensors are widely used to collect high-spatial-resolution particulate matter data that traditional reference monitoring devices cannot. In addition to the mass concentration, the number concentration and size distribution are also fundamental in determining the origin and hazard level of particulate pollution. Therefore, low-cost optical sensors have been improved to establish optical particle sizers (OPSs). In this study, a low-cost OPS, the Nova SDS029, is introduced, and it is evaluated in comparison to two reference instruments-the GRIMM 11-D and the TSI 3330. We first tested the sizing accuracy using polystyrene latex spheres. Then, we assessed the mass and number size distribution accuracy in three application scenarios: indoor smoking, ambient air quality, and mobile monitoring. The evaluations suggest that the low-cost SDS029 rivals research-grade optical sizers in many aspects. For example, (1) the particle diameters obtained with the SDS029 are close to the reference instruments (usually < 10%) in the 0.3-5 µm range; (2) the number of particles and mass concentration are highly correlated (r ≥ 0.99) with the values obtained with the reference instruments; and (3) the SDS029 slightly underestimates the number concentration, but the derived PM2.5 values are closer to monitoring station than the reference instruments. The successful application of the SDS029 in multiple scenarios suggests that a plausible particle size distribution can be obtained in an easy and cost-efficient way. We believe that low-cost OPSs will increasingly be used to map the sources and risk levels of particles at the city scale.

The engineered CRISPR-Mb2Cas12a variant enables sensitive and fast nucleic acid-based pathogens diagnostics in the field.

Existing CRISPR/Cas12a-based diagnostic platforms offer accurate and vigorous monitoring of nucleic acid targets, but have the potential to be further optimized for more efficient detection. Here, we profiled 16 Cas12a orthologs, focusing on their trans-cleavage activity and their potential as diagnostic enzymes. We observed the Mb2Cas12a has more robust trans-cleavage activity than other orthologs, especially at lower temperatures. An engineered Mb2Cas12a-RRVRR variant presented robust trans-cleavage activity and looser PAM constraints. Moreover, we found the existing one-pot assay, which simultaneously performed Recombinase Polymerase Amplification (RPA) and Cas12a reaction in one system, resulted in the loss of single-base discrimination during diagnosis. Therefore, we designed a reaction vessel that physically separated the RPA and Cas12a steps while maintaining a closed system. This isolated but closed system made diagnostics more sensitive and specific and effectively prevented contamination. This shelved Mb2Cas12a-RRVRR variant-mediated assay detected various targets in less than 15 min and exhibited equal or greater sensitivity than qPCR when detecting bacterial pathogens, plant RNA viruses and genetically modified crops. Overall, our findings further improved the efficiency of the current CRISPR-based diagnostic system and undoubtedly have great potential for highly sensitive and specific detection of multiple sample types.

Implementing a novel capture and ligation probe-PCR method in mass screen and treatment to support malaria elimination efforts in the China-Myanmar border region.

BACKGROUND: Mass screening and treatment (MSAT) for malaria elimination lacks an ideal diagnostic tool to allow sensitive and affordable test of the target population in the field. This study evaluated whether Capture and Ligation Probe-PCR (CLIP-PCR) could be used in a field MSAT in Laiza City, Myanmar. METHODS: On day 0, two dried blood spots were collected from each participant. On day 1, all samples were screened for Plasmodium in a 20 m2 laboratory with workbench, a biosafety cabinet, a refrigerator, a benchtop shaking incubator and a qPCR machine, by four technicians using CLIP-PCR with sample pooling, at a health clinic of the Chinese bordering town of Nabang. On day 2, all positives were followed up and treated. RESULTS: Of 15,038 persons (65% of the total population) screened, 204 (1.36%) were CLIP-PCR positives. Among them, 188, 14, and 2 were infected with Plasmodium vivax, Plasmodium falciparum, and P. vivax/P. falciparum mix, respectively. The testing capacity was 538 persons/day, with a cost of US$0.92 /person. The proportion of submicroscopic infection was 64.7%. All positive individuals received treatment within 72 h after blood collection. CONCLUSION: Using CLIP-PCR in MSAT in low transmission settings can support the malaria elimination efforts in the China-Myanmar border region.

Photocatalytic and oxidation mechanisms of Fe-Ag@AgCl: Effect on co-existing arsenic (III) and Escherichia coli.

To address the drinking safety problems associated with high arsenic(III) (As(III)) and bacteria in underground water, core-shell Fe-Ag@AgCl nanowires were synthesized and exhibited excellent photocatalytic oxidation effects on co-existing As(III) and Escherichia coli (E. coli). With the introduction of Fe, the nanowires that were used 5 times could be easily magnetically collected, and the As(III) oxidation effect of these re-chlorinated nanowires increased from 39% to 60%. E. coli was completely inactivated within 60 min without photoreactivation after 20 min. Extracellular polymeric substances have play a protective role in the disinfection process. Quenching testing results confirmed that, except for the superoxide radical (•O2-), the subdominant active species were different for different objects: hole (hVB+) to As(III) and hydroxyl radical (•OH) to E. coli. Therefore the system with co-existing As(III) and E. coli, the inactivation effect of Fe-Ag@AgCl on E. coli decreased remarkably with an increase in As(III) concentration, while the oxidation process of As(III) was not significantly affected by E. coli until E. coli was increased to 108 cfu/mL. The photocatalytic process of co-existing As(III) and E. coli is displayed in a schematic diagram and was tested using desired results obtained from field groundwater in Xiantao City, Hubei Province. The function of Fe in band structures and density of states was analyzed using plane-wave density functional theory. These magnetic nanowires presented excellent photocatalytic ability on co-existing As(III) and E. coli, and provided new insights into drinking water safety in high-arsenic areas.

Cryogen-free 400 MHz (9.4 T) solid state MAS NMR system with liquid state NMR potential.

We show that the temporal magnetic field distortion generated by the Cold Head operation can be removed and high quality Solid-State Magic Angle Spinning NMR results can be obtained with a cryogen-free magnet. The compact design of the cryogen-free magnets allows for the probe to be inserted either from the bottom (as in most NMR systems) or, more conveniently, from the top. The magnetic field settling time can be made as short as an hour after a field ramp. Therefore, a single cryogen-free magnet can be used at different fixed fields. The magnetic field can be changed every day without compromising the measurement resolution.

Triazine Herbicides Risk Management Strategies on Environmental and Human Health Aspects Using In-Silico Methods.

As an effective herbicide, 1, 3, 5-Triazine herbicides (S-THs) are used widely in the pesticide market. However, due to their chemical properties, S-THs severely threaten the environment and human health (e.g., human lung cytotoxicity). In this study, molecular docking, Analytic Hierarchy Process-Technique for Order Preference by Similarity to the Ideal Solution (AHP-TOPSIS), and a three-dimensional quantitative structure-active relationship (3D-QSAR) model were used to design S-TH substitutes with high herbicidal functionality, high microbial degradability, and low human lung cytotoxicity. We discovered a substitute, Derivative-5, with excellent overall performance. Furthermore, Taguchi orthogonal experiments, full factorial design of experiments, and the molecular dynamics method were used to identify three chemicals (namely, the coexistence of aspartic acid, alanine, and glycine) that could promote the degradation of S-THs in maize cropping fields. Finally, density functional theory (DFT), Estimation Programs Interface (EPI), pharmacokinetic, and toxicokinetic methods were used to further verify the high microbial degradability, favorable aquatic environment, and human health friendliness of Derivative 5. This study provided a new direction for further optimizations of novel pesticide chemicals.

Significant Change of Metal Cations in Geometric Sites by Magnetic-Field Annealing FeCo2 O4 for Enhanced Oxygen Catalytic Activity.

The application of magnetic fields in the oxygen reduction/evolution reaction (ORR/OER) testing for electrocatalysts has attracted increasing interest, but it is difficult to characterize on-site surface reconstruction. Here, a strategy is developed for annealing-treated FeCo2 O4 nanofibers at a magnetic field of 2500 Oe, named FeCo2 O4 -M, showing a right-shifted half-wave potential of 20 mV for the ORR and a left-shifted overpotential of 60 mV at 10 mV cm-2 for the OER as compared with its counterpart. Magnetic characterizations indicate that FeCo2 O4 -M shows the spin-state transition of cations from a low-spin state to an intermediate-spin state compared with FeCo2 O4 . Mössbauer spectra show that the Fe3+ ion in the octahedral site (0.76) of FeCo2 O4 -M is more than that of FeCo2 O4 (0.71), indicating the effective stimulus of metal cations in geometric sites by magnetic-field annealing. Furthermore, theoretical calculations demonstrate that the d-band centers (εd ) of Co 3d and Fe 3d in the tetrahedral and octahedral sites of the FeCo2 O4 -M nanofibers shift close to the Fermi level, revealing the enhanced mechanism of the ORR/OER activity.

Field application of nanoliposomes delivered quercetin by inhibiting specific hsp70 gene expression against plant virus disease.

BACKGROUND: The annual economic loss caused by plant viruses exceeds 10 billion dollars due to the lack of ideal control measures. Quercetin is a flavonol compound that exerts a control effect on plant virus diseases, but its poor solubility and stability limit the control efficiency. Fortunately, the development of nanopesticides has led to new ideas. RESULTS: In this study, 117 nm quercetin nanoliposomes with excellent stability were prepared from biomaterials, and few surfactants and stabilizers were added to optimize the formula. Nbhsp70er-1 and Nbhsp70c-A were found to be the target genes of quercetin, through abiotic and biotic stress, and the nanoliposomes improved the inhibitory effect at the gene and protein levels by 33.6 and 42%, respectively. Finally, the results of field experiment showed that the control efficiency was 38% higher than that of the conventional quercetin formulation and higher than those of other antiviral agents. CONCLUSION: This research innovatively reports the combination of biological antiviral agents and nanotechnology to control plant virus diseases, and it significantly improved the control efficiency and reduced the use of traditional chemical pesticides.

Field detection of multiple RNA viruses/viroids in apple using a CRISPR/Cas12a-based visual assay.

Co-infection of apple trees with several viruses/viroids is common and decreases fruit yield and quality. Accurate and rapid detection of these viral pathogens helps to reduce losses and prevent virus spread. Current molecular detection assays used for apple viruses require specialized and expensive equipment. Here, we optimized a CRISPR/Cas12a-based nucleic acid detection platform for the diagnosis of the most prevalent RNA viruses/viroid in apple, namely Apple necrotic mosaic virus (ApNMV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple chlorotic leaf spot virus (ACLSV) and Apple scar skin viroid (ASSVd). We detected each RNA virus/viroid directly from crude leaf extracts after simultaneous multiplex reverse transcription-recombinase polymerase amplification (RT-RPA) with high specificity. Positive results can be distinguished by the naked eye via oligonucleotide-conjugated gold nanoparticles. The CRISPR/Cas12a-RT-RPA platform exhibited comparable sensitivity to RT-qPCR, with limits of detection reaching 250 viral copies per reaction for ASPV and ASGV and 2500 copies for the others. However, this protocol was faster and simpler, requiring an hour or less from leaf harvest. Field tests showed 100% agreement with RT-PCR detection for 52 samples. This novel Cas12a-based method is ideal for rapid and reliable detection of apple viruses in the orchard without the need to send samples to a specialized laboratory.

Recent Advances in Sulfidated Zerovalent Iron for Contaminant Transformation.

2021 marks 10 years since controlled abiotic synthesis of sulfidated nanoscale zerovalent iron (S-nZVI) for use in site remediation and water treatment emerged as an area of active research. It was then expanded to sulfidated microscale ZVI (S-mZVI) and together with S-nZVI, they are collectively referred to as S-(n)ZVI. Heightened interest in S-(n)ZVI stemmed from its significantly higher reactivity to chlorinated solvents and heavy metals. The extremely promising research outcomes during the initial period (2011-2017) led to renewed interest in (n)ZVI-based technologies for water treatment, with an explosion in new research in the last four years (2018-2021) that is building an understanding of the novel and complex role of iron sulfides in enhancing reactivity of (n)ZVI. Numerous studies have focused on exploring different S-(n)ZVI synthesis approaches, and its colloidal, surface, and reactivity (electrochemistry, contaminant selectivity, and corrosion) properties. This review provides a critical overview of the recent milestones in S-(n)ZVI technology development: (i) clear insights into the role of iron sulfides in contaminant transformation and long-term aging, (ii) impact of sulfidation methods and particle characteristics on reactivity, (iii) broader range of treatable contaminants, (iv) synthesis for complete decontamination, (v) ecotoxicity, and (vi) field implementation. In addition, this review discusses major knowledge gaps and future avenues for research opportunities.

Detection of Ground Contact Times with Inertial Sensors in Elite 100-m Sprints under Competitive Field Conditions.

This study describes a method for extracting the stride parameter ground contact time (GCT) from inertial sensor signals in sprinting. Five elite athletes were equipped with inertial measurement units (IMU) on their ankles and performed 34 maximum 50 and 100-m sprints. The GCT of each step was estimated based on features of the recorded IMU signals. Additionally, a photo-electric measurement system covered a 50-m corridor of the track to generate ground truth data. This corridor was placed interchangeably at the first and the last 50-ms of the track. In total, 863 of 889 steps (97.08%) were detected correctly. On average, ground truth data were underestimated by 3.55 ms. The root mean square error of GCT was 7.97 ms. Error analyses showed that GCT at the beginning and the end of the sprint was classified with smaller errors. For single runs the visualization of step-by-step GCT was demonstrated as a new diagnostic instrument for sprint running. The results show the high potential of IMUs to provide the temporal parameter GCT for elite-level athletes.

A method for fast field settling in cryogen-free superconducting magnets for NMR.

We propose a fast algorithm to energise a cryogen free magnet to a highly persistent state. A decay rate as low as 0.021 â€‹ppm/h can be achieved in less than an hour after reaching the target field. The decay rate drops further to 0.0004 â€‹ppm/h in the following 48 â€‹h. This procedure can be applied at different values of target field, which makes it feasible to use a single magnet for study of various NMR lines at different fields. The mechanism of establishing a highly stable magnetic field can be understood on the basis of the magnetic properties of the superconducting wire, which were studied using a vibrating sample magnetometer. The results confirm the high quality of the superconducting wire and joints.

On the magnetic field stability of cryogen-free magnets for magnetic resonance applications.

The temporal magnetic field variation associated with Cold Head operation in cryogen-free magnets was studied. Three different mechanisms for such variations were tested separately and rated by their importance. It was found that mechanical displacement of the magnet inside the cryostat is the main issue of magnetic field perturbation. In a cryostat with the Gifford- McMahon type of cryocooler, motion of the displacer with magnetic material inside also produces significant field modulation. The temperature variation of the magnet, although noticeable, leads to smaller field distortions compared to the previous two factors. It was shown that the temporal magnetic field variation could be reduced down to below 20 â€‹ppb level that could be acceptable for MRI and MAS NMR applications. It was also shown that a single cryogen-free magnet could be easily used at different fields on a day-to-day basis without compromising the field stability unlike magnets housed in a liquid helium reservoir.

Towards Improved Field Application of Using Distributed Temperature Sensing for Soil Moisture Estimation: A Laboratory Experiment.

The "dual probe heat pulse" (DPHP) method using actively heated fiber optic (AHFO) cables combined with distributed temperate sensing (DTS) technology has been developed for monitoring thermal properties and soil water content at the field scale. Field scale application, however, requires the use of robust and thicker fiber optic cables, corroborating the assumption of an infinite thin heat source in the evaluation process. We therefore included a semi-analytical solution of the heat transport equation into the evaluation procedure in order to consider the finite thermal properties of the heating cable without a calibration procedure to estimate effective thermal properties of the soil. To test this new evaluation procedure, we conducted a laboratory experiment and tested different heating scenarios to infer soil moisture from volumetric heat capacity. Estimates were made by analyzing the shift of the temperature amplitude at the sensing cable and the characteristics of the response heating curve. The results were compared with results from the calibrated infinite line source solution and in situ water content point measurements and showed a good approximation of thermal properties for strong and short heat pulses. Volumetric water content estimates are similarly accurate to the results of the calibrated infinite line source solution. Problems arose with the cable spacing and the resettlement process after burying the cable.

Impact of Saw Dust Application on the Distribution of Potentially Toxic Metals in Contaminated Soil.

The need to develop an approach for the reclamation of contaminated site using locally available agricultural waste has been considered. The present study investigated the application of sawdust as an effective amendment in the immobilization of potentially toxic metals (PTMs) by conducting a greenhouse experiment on soil collected from an automobile dumpsite. The amended and non-amended soil samples were analyzed for their physicochemical parameters and sequential extraction of PTMs. The results revealed that application of amendment had positive impact on the physicochemical parameters as organic matter content and cation exchange capacity increased from 12.1% to 12.8% and 16.4 to 16.8 meq/100 g respectively. However, the mobility and bioavalability of these metals was reduced as they were found to be distributed mostly in the non-exchangeable phase of soil. Therefore, application of sawdust successfully immobilized PTMs and could be applied for future studies in agricultural soil reclamation.

Control effect and field application of four predatory Orius species on Megalurothrips usitatus (Thysanoptera: Thripidae).

Megalurothrips usitatus (Bagrall) is one of the most important pests of cowpea, Vigna unguiculata (Linn.) Walp in South China. Four Orius species, including Orius minutus (L.), Orius nagaii (Yasunaga), Orius sauteri (Poppius), and Orius strigicollis (Poppius), have been commercially produced and widely used as natural enemies of pests in China. In this study, we evaluated the control efficiency of these Orius species on M. usitatus in tropical Hainan Province, China, by recording the survival rates, developmental times, and predation effects in laboratory and semi-field conditions. Laboratory experiments showed that all these 4 Orius species preyed on M. usitatus under the experimental temperatures (25, 30, and 35 °C), and O. strigicollis exhibited the highest survival rate and predation effect. Semi-field cage experiments showed that the control effect of 4 Orius species on M. usitatus was significantly higher than that under normal chemical control, with O. strigicollis having the highest effect. Greenhouse experiments in Hainan Province, China, confirmed that O. strigicollis had a significant control effect on M. usitatus. Our study indicated that O. strigicollis has a significant potential for the control of M. usitatus in cowpea fields in southern China.

Field and postharvest application of microencapsulated Yamadazyma mexicana LPa14: anthracnose control and effect on postharvest quality in avocado (Persea americana Mill. cv. Hass).

BACKGROUND: Anthracnose caused by species of Colletotrichum is the most important disease of avocado fruit. The quiescent infection develops in the field, hence, its control from the preharvest stage is necessary. The field application of microencapsulated Yamadazyma mexicana LPa14 could prevent the establishment of Colletotrichum gloeosporioides and reduce the losses in avocado production. This study aimed to evaluate the effectiveness of microencapsulated Y. mexicana applied in the field and postharvest for the anthracnose control in avocado, to evaluate the population dynamics of Y. mexicana in flowers and fruits and the effect of the yeast on the avocado quality. RESULTS: The concentrations of microencapsulated Y. mexicana after field application ranged from 4.58 to 6.35 log CFU g-1. The population of microencapsulated yeast in flowers and fruits was always higher than treatments with fresh cells. Preharvest application of fresh and microencapsulated Y. mexicana significantly reduced the severity of anthracnose by 71-80% and 84-96%, respectively, in avocado fruits stored at 25 °C. Moreover, at 6 °C and ripening at 25 °C, the fresh yeast reduced the severity by 87-90% and the microencapsulated yeast by 91-93%. However, yeast treatments applied in the field + postharvest under cool conditions were more effective in reducing 100% of anthracnose. Treatments did not negatively affect the quality parameters of the avocado fruits. CONCLUSION: Yamadazyma mexicana microencapsulated by electrospraying is a promising bioformulation for the management of anthracnose in avocados at preharvest and postharvest levels. Yamadazyma mexicana offers a new biological control solution for growers in avocado orchards. © 2024 Society of Chemical Industry.

Optimizing a twin-chamber system for direct ozone production rate measurement.

High Ozone Production Rate (OPR) leads to O3 pollution episodes and adverse human health outcomes. OPR observation (Obs-OPR) and OPR modelling (Mod-OPR) have been obtained from observed and modelled peroxy radicals and nitrogen oxides. However, discrepancies between them remind of an imperfect understanding of O3 photochemistry. Direct measurement of OPR (Mea-OPR) by a twin-chamber system emerges. Herein, we optimized Mea-OPR design, i.e., minimizing the chamber surface area to volume ratio (S/V) to 9.8 m-1 from 18 m-1 and the dark uptake coefficient of O3 to 9.9 × 10-9 from 7.1 × 10-8 in the literature. In addition, control experiments further revealed and quantified a photo-enhanced O3 uptake, and therefore recommended an essential correction of Mea-OPR. We finally characterized a measurement uncertainty of ±38% and a detection limit of 3.2 ppbv h-1 (3SD), which suggested that Mea-OPR would be sensitive enough to measure OPR in urban or suburban environments. Further application of this system in urban Beijing during the Beijing 2022 Olympic Winter Games recorded a noontime OPR of 7.3 (±3.3, 1SD) ppbv h-1. These observational results added up to our confidence in future field application of Mea-OPR, to facilitate pollution control policy evaluation and to shed light on O3 photochemistry puzzle.

Utility of a modified o-DGT passive sampler for measurement of bisphenol analogues in freshwater and coastal waters.

Bisphenol analogues (BPs) are commonly found in riverine and coastal waters. However, the lack of a reliable and robust passive sampling method has hindered our ability to monitor these compounds in aquatic systems. The study developed a novel organic-diffusive gradients in thin film (o-DGT) sampler based on stainless steel mesh membrane, polyacrylamide diffusive gel, and hydrophilic-lipophilic balance (HLB) binding gel. This innovative design tackled issues of filter membrane sorption in traditional o-DGT devices and potential gel damage in membrane-less o-DGT devices, showing promising application prospects. The mass accumulation of 15 target BPs was linear over 10 days in both freshwater (r2 ≥ 0.92) and seawater (r2 ≥ 0.94), with no saturation observed. The diffusion coefficients (D) through polyacrylamide diffusive gels ranged from 4.04 × 10-6 to 5.77 × 10-6 cm2 s-1 in freshwater and from 1.74 × 10-6 to 4.69 × 10-6 cm2 s-1 in seawater for the target BPs (except for bisphenol PH) at 22 °C. The D values of the target BPs in seawater were lower than those in freshwater due to the high salinity in seawater (35 ‰). The o-DGT samplers demonstrated good integrity in field applications. The total concentrations of the eight detected BPs ranged from 9.2 to 323 ng L-1, which was consistent with the measurements obtained by grab sampling. Among all BPs, bisphenol S, bisphenol F, and bisphenol A were consistently detected at all sites using both sampling methods. The concentrations of some novel BPs in coastal water measured by grab sampling were comparable to those measured in rivers, suggesting the need to strengthen pollution control of BPs in coastal areas. These results indicate that the o-DGT passive sampling method developed in the present study can be effectively used for monitoring BPs in freshwater and coastal environments.

Safe and efficient drilling and completion technology for deep shale gas in Sichuan and Chongqing.

The world is rich in coalbed methane (CBM) resources and has broad exploration and development prospects. In this paper, first, the technical difficulties of drilling and completion in deep shale formations in the Sichuan and Chongqing region is systematically summarized. Second, a systematic evaluation was conducted on the optimization of temperature resistance performance and trajectory control technology of the rotary guidance system. Third, evaluation and economic analysis were conducted on the experimental effects of different technologies. Results show that: (a) the optimization technology for temperature resistance performance of integrated high-temperature resistant guide head and surface cooling equipment has been formed, which can effectively reduce the circulation cooling time and improve drilling efficiency. (b) Real time measurement of underground engineering parameters and monitoring and evaluation of wellbore cleanliness can reduce drilling risks, while achieving quantitative evaluation of drilling fluid gas content. (c) Assisted by real-time optimization technology of mechanical drilling speed based on underground surface engineering parameters, the acceleration effect has been significantly improved.