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1.
J Environ Manage ; 365: 121589, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38963969

ABSTRACT

Subsurface dams have been recognized as one of the most effective measures for preventing saltwater intrusion. However, it may result in large amounts of residual saltwater being trapped upstream of the dam and take years to decades to remove, which may limit the utilization of fresh groundwater in coastal areas. In this study, field-scale numerical simulations were used to investigate the mechanisms of residual saltwater removal from a typical stratified aquifer, where an intermediate low-permeability layer (LPL) exists between two high-permeability layers, under the effect of seasonal sea level fluctuations. The study quantifies and compares the time of residual saltwater removal (Tre) for constant sea level (CSL) and seasonally varying sea level (FSL) scenarios. The modelling results indicate that, in most cases, seasonal fluctuations in sea level facilitate the dilution of residual saltwater and thus accelerate residual saltwater removal compared to a static sea level scenario. However, accounting for seasonal sea level variations may increase the required critical dam height (the minimum dam height required to achieve complete residual saltwater removal). Sensitivity analyses show that Tre decreases with increasing height of subsurface dam (Hd) under CSL or weaker sea level fluctuation scenarios; however, when the magnitude of sea level fluctuation is large, Tre changes non-monotonically with Hd. Tre decreases with increasing distance between subsurface dam and ocean for both CSL and FSL scenarios. We also found that stratification model had a significant effect on Tre. The increase in LPL thickness for both CSL and FSL scenarios leads to a decrease in Tre and critical dam height. Tre generally shows a non-monotonically decreasing trend as LPL elevation increases. These quantitative analyses provide valuable insights into the design of subsurface dams in complex situations.

2.
Small ; : e2311299, 2024 Feb 16.
Article in English | MEDLINE | ID: mdl-38366314

ABSTRACT

Silicon (Si) anode has attracted broad attention because of its high theoretical specific capacity and low working potential. However, the severe volumetric changes of Si particles during the lithiation process cause expansion and contraction of the electrodes, which induces a repeatedly repair of solid electrolyte interphase, resulting in an excessive consuming of electrolyte and rapid capacity decay. Clearly known the deformation and stress changing at µÎµ resolution in the Si-based electrode during battery operation provides invaluable information for the battery research and development. Here, an in operando approach is developed to monitor the stress evolution of Si anode electrodes via optical fiber Bragg grating (FBG) sensors. By implanting FBG sensor at specific locations in the pouch cells with different Si anodes, the stress evolution of Si electrodes has been systematically investigated, and Δσ/areal capacity is proposed for stress assessment. The results indicate that the differences in stress evolution are nested in the morphological changes of Si particles and the evolution characteristics of electrode structures. The proposed technique provides a brand-new view for understanding the electrochemical mechanics of Si electrodes during battery operation.

4.
Int J Mol Sci ; 24(21)2023 Nov 02.
Article in English | MEDLINE | ID: mdl-37958874

ABSTRACT

Colletotrichum higginsianum is a major pathogen causing anthracnose in Chinese flowering cabbage (Brassica parachinensis), posing a significant threat to the Chinese flowering cabbage industry. The conidia of C. higginsianum germinate and form melanized infection structures called appressoria, which enable penetration of the host plant's epidermal cells. However, the molecular mechanism underlying melanin biosynthesis in C. higginsianum remains poorly understood. In this study, we identified two enzymes related to DHN-melanin biosynthesis in C. higginsianum: ChPks and ChThr1. Our results demonstrate that the expression levels of genes ChPKS and ChTHR1 were significantly up-regulated during hyphal and appressorial melanization processes. Furthermore, knockout of the gene ChPKS resulted in a blocked DHN-melanin biosynthetic pathway in hyphae and appressoria, leading to increased sensitivity of the ChpksΔ mutant to cell-wall-interfering agents as well as decreased turgor pressure and pathogenicity. It should be noted that although the Chthr1Δ mutant still exhibited melanin accumulation in colonies and appressoria, its sensitivity to cell-wall-interfering agents and turgor pressure decreased compared to wild-type strains; however, complete loss of pathogenicity was not observed. In conclusion, our results indicate that DHN-melanin plays an essential role in both pathogenicity and cell wall integrity in C. higginsianum. Specifically, ChPks is crucial for DHN-melanin biosynthesis while deficiency of ChThr1 does not completely blocked melanin production.


Subject(s)
Colletotrichum , Melanins , Virulence , Melanins/metabolism , Cell Wall/metabolism
5.
Sci Rep ; 13(1): 15910, 2023 09 23.
Article in English | MEDLINE | ID: mdl-37741874

ABSTRACT

This study evaluated the aerosol exposure risks while using common noninvasive oxygenation devices. A simulated mannequin was designed to breathe at a minute ventilation of 20 L/min and used the following oxygen-therapy devices: nasal cannula oxygenation (NCO) at 4 and 15 L/min, nonrebreathing mask (NRM) at 15 L/min, simple mask at 6 L/min, combination of NCO at 15 L/min and NRM at 15 L/min, high-flow nasal cannula (HFNC) at 50 L/min, and flush rate NRM. Two-dimension of the dispersion distance and the aerosol concentrations were measured at head, trunk, and foot around the mannequin for over 10 min. HFNC and flush-rate NRM yielded the longest dispersion distance and highest aerosol concentrations over the three sites of the mannequin than the other oxygenation devices and should use with caution. For flow rates of < 15 L/min, oxygenation devices with mask-like effects, such as NRM or NCO with NRM, decreased aerosol dispersion more effectively than NCO alone or a simple mask. In the upright position, the foot area exhibited the highest aerosol concentration regardless of the oxygenation device than the head-trunk areas of the mannequin. Healthcare workers should be alert even at the foot side of the patient while administering oxygenation therapy.


Subject(s)
Oxygen Inhalation Therapy , Smoke , Humans , Aerosols , Oxygen Inhalation Therapy/methods , Lung , Administration, Inhalation
6.
Front Immunol ; 14: 1232981, 2023.
Article in English | MEDLINE | ID: mdl-37691954

ABSTRACT

Background: The evidence from observational studies on the association between the use of aspirin and the risk of hayfever or allergic rhinitis is conflicting, with a dearth of high-quality randomized controlled trials. Objective: This study aims to investigate the causal relationship between aspirin use and the risk of hayfever or allergic rhinitis. Methods: We conducted a two-sample Mendelian randomization (MR) analysis using the inverse-variance weighted (IVW), weighted median, and MR-Egger regression methods. We utilized publicly available summary statistics datasets from genome-wide association studies (GWAS) meta-analyses on aspirin use in individuals of European descent (n = 337,159) as the exposure variable, and a GWAS on doctor-diagnosed hayfever or allergic rhinitis in individuals from the UK Biobank (n = 83,529) as the outcome variable. Results: We identified 7 single nucleotide polymorphisms (SNPs) at genome-wide significance from the GWASs associated with aspirin use as instrumental variables (P<5×10-8; linkage disequilibrium r2 <0.1). The IVW method provided evidence supporting a causal association between aspirin use and reduced risk of hayfever or allergic rhinitis (ß = -0.349, SE = 0.1356, P = 0.01008). MR-Egger regression indicated no causal association between aspirin use and hayfever or allergic rhinitis (ß = -0.3742, SE = 0.3809, P = 0.371), but the weighted median approach yielded evidence of a causal association (ß = -0.4155, SE = 0.1657, P = 0.01216). Cochran's Q test and the funnel plot indicated no evidence of heterogeneity and asymmetry, indicating no directional pleiotropy. Conclusion: The findings of the MR analysis support a potential causal relationship between aspirin use and the reduced risk of hayfever or allergic rhinitis.


Subject(s)
Rhinitis, Allergic, Seasonal , Rhinitis, Allergic , Humans , Aspirin , Genome-Wide Association Study , Mendelian Randomization Analysis , Rhinitis, Allergic/genetics
7.
Sci Rep ; 13(1): 12552, 2023 08 02.
Article in English | MEDLINE | ID: mdl-37532861

ABSTRACT

To evaluate aerosol exposure risk and prevention strategies during bystander, pre-hospital, and inpatient cardiopulmonary resuscitation (CPR). This study compared hands-only CPR, CPR with a surgical or N95 mask, and CPR with a non-rebreather mask at 15 L/min. 30:2 compression-ventilation ratio CPR was tested with face-mask ventilation (FMV), FMV with a high efficiency particulate air (HEPA) filter; supraglottic airway (SGA), SGA with a surgical mask, SGA with a HEPA filter, or SGA with both. Continuous CPR was tested with an endotracheal tube (ET), ET with a surgical mask, a HEPA filter, or both. Aerosol concentration at the head, trunk, and feet of the mannequin were measured to evaluate exposure to CPR personnel. Hands-only CPR with a surgical or N95 face mask coverings and ET tube ventilation CPR with filters showed the lowest aerosol exposure among all study groups, including CPR with NRM oxygenation, FMV, and SGA ventilation. NRM had a mask effect and reduced aerosol exposure at the head, trunk, and feet of the mannequin. FMV with filters during 30:2 CPR reduced aerosol exposure at the head and trunk, but increased at the feet of the mannequin. A tightly-sealed SGA when used with a HEPA filter, reduced aerosol exposure by 21.00-63.14% compared with a loose-fitting one. Hands-only CPR with a proper fit surgical or N95 face mask coverings is as safe as ET tube ventilation CPR with filters, compared with CPR with NRM, FMV, and SGA. FMV or tight-sealed SGA ventilation with filters prolonged the duration to achieve estimated infective dose of SARS-CoV-2 2.4-2.5 times longer than hands-on CPR only. However, a loose-fitting SGA is not protective at all to chest compressor or health workers standing at the foot side of the victim, so should be used with caution even when using with HEPA filters.


Subject(s)
COVID-19 , Cardiopulmonary Resuscitation , Humans , Manikins , Inpatients , COVID-19/prevention & control , SARS-CoV-2 , Respiratory Aerosols and Droplets , Intubation, Intratracheal , Hospitals
8.
Ann Emerg Med ; 80(1): 22-34, 2022 07.
Article in English | MEDLINE | ID: mdl-35469678

ABSTRACT

STUDY OBJECTIVE: To evaluate aerosol dispersion and exposure risk during oxygenation therapy among health care personnel. METHODS: This study compared the aerosol dispersion effect produced through continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), BiPAP with face coverings, a high-flow nasal cannula (HFNC) with face coverings, nasal cannula oxygenation (NCO) at 15 L/min with face coverings, nonrebreather mask (NRM), and ventilator-assisted preoxygenation (VAPOX) during oxygenation therapy at a minute ventilation of 10 L/min and 20 L/min. The length and width of aerosol dispersion were recorded, and aerosol concentrations were then detected at a mannequin's head, trunk, and feet. RESULTS: The average length dispersion distance of CPAP was 47.12 cm (SD, 12.56 cm), of BiPAP was 100.13 cm (SD, 6.03 cm), of BiPAP with face coverings was 62.20 cm (SD, 8.46 cm), of HFNC with face coverings was 67.09 cm (SD, 12.74 cm); of NCO with face coverings was 85.55 cm (SD, 7.28 cm); and of NRM was 63.08 cm (SD, 15.33 cm); VAPOX showed no visible dispersion. The aerosol concentrations at the feet under CPAP and at the head under BiPAP were significantly higher than those observed without an oxygen device. Compared with no oxygen device, the aerosol concentration with HFNC was higher at the mannequin's head, trunk, and feet; whereas it was lower with VAPOX and NRM. Moreover, when translated to the number of virus particles required to infect medical personnel (Nf), VAPOX took more time to achieve Nf than other devices. CONCLUSION: Strong flow from the oxygenation devices resulted in increased aerosol concentrations. CPAP at the feet side, BiPAP at the head side, HFNC, and NCO with face coverings significantly increase aerosol exposure and should be used with caution. Aerosol concentrations at all positions were lower with NRM and VAPOX.


Subject(s)
Cannula , Noninvasive Ventilation , Aerosols , Continuous Positive Airway Pressure , Humans , Oxygen , Oxygen Inhalation Therapy/methods , Ventilators, Mechanical
9.
Sensors (Basel) ; 22(1)2022 Jan 02.
Article in English | MEDLINE | ID: mdl-35009870

ABSTRACT

Oxyhemoglobin saturation by pulse oximetry (SpO2) has always played an important role in the diagnosis of symptoms. Considering that the traditional SpO2 measurement has a certain error due to the number of wavelengths and the algorithm and the wider application of machine learning and spectrum combination, we propose to use 12-wavelength spectral absorption measurement to improve the accuracy of SpO2 measurement. To investigate the multiple spectral regions for deep learning for SpO2 measurement, three datasets for training and verification were built, which were constructed over the spectra of first region, second region, and full region and their sub-regions, respectively. For each region under the procedures of optimization of our model, a thorough of investigation of hyperparameters is proceeded. Additionally, data augmentation is preformed to expand dataset with added noise randomly, increasing the diversity of data and improving the generalization of the neural network. After that, the established dataset is input to a one dimensional convolution neural network (1D-CNN) to obtain a measurement model of SpO2. In order to enhance the model accuracy, GridSearchCV and Bayesian optimization are applied to optimize the hyperparameters. The optimal accuracies of proposed model optimized by GridSearchCV and Bayesian Optimization is 89.3% and 99.4%, respectively, and trained with the dataset at the spectral region of six wavelengths including 650 nm, 680 nm, 730 nm, 760 nm, 810 nm, 860 nm. The total relative error of the best model is only 0.46%, optimized by Bayesian optimization. Although the spectral measurement with more features can improve the resolution ability of the neural network, the results reveal that the training with the dataset of the shorter six wavelength is redundant. This analysis shows that it is very important to construct an effective 1D-CNN model area for spectral measurement using the appropriate spectral ranges and number of wavelengths. It shows that our proposed 1D-CNN model gives a new and feasible approach to measure SpO2 based on multi-wavelength.


Subject(s)
Deep Learning , Bayes Theorem , Machine Learning , Neural Networks, Computer , Oximetry
10.
Nanomicro Lett ; 14(1): 9, 2021 Dec 03.
Article in English | MEDLINE | ID: mdl-34862572

ABSTRACT

Iron hexacyanoferrate (FeHCF) is a promising cathode material for sodium-ion batteries. However, FeHCF always suffers from a poor cycling stability, which is closely related to the abundant vacancy defects in its framework. Herein, post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of high-quality FeHCF in a highly concentrated Na4Fe(CN)6 solution. Both the post-synthetic and in-situ vacancy repaired FeHCF products (FeHCF-P and FeHCF-I) show the significant decrease in the number of vacancy defects and the reinforced structure, which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF. In particular, FeHCF-P delivers a reversible discharge capacity of 131 mAh g-1 at 1 C and remains 109 mAh g-1 after 500 cycles, with a capacity retention of 83%. FeHCF-I can deliver a high discharge capacity of 158.5 mAh g-1 at 1 C. Even at 10 C, the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g-1 and retains 75% after 800 cycles. This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.

11.
ACS Appl Mater Interfaces ; 13(32): 38194-38201, 2021 Aug 18.
Article in English | MEDLINE | ID: mdl-34342445

ABSTRACT

Lithium loss during the initial charge process inevitably reduces the capacity and energy density of lithium-ion batteries. Cathode additives are favored with respect to their controllable prelithiation degree and scalable application; however, the insulating nature of their delithiation products retards electrode reaction kinetics in subsequent cycles. Herein, we propose a prelithiation separator by modifying a commercial separator with a Li2S/Co nanocomposite to compensate for the initial capacity loss. The Li2S/Co coating layer extracts active lithium ion during the charge process and shows a delithiation capacity of 993 mA h g-1. When paired with a LiFePO4|graphite full cell, the reversible capacity is increased from 112.6 to 150.3 mA h g-1, leading to a 29.5% boost in the energy density. The as-prepared pouch cell also demonstrates a stable cycling performance. The excellent electrochemical performance and the scalable production of the prelithiation separator reveal its great potential in lithium-ion battery industry application.

12.
Materials (Basel) ; 14(16)2021 Aug 08.
Article in English | MEDLINE | ID: mdl-34442969

ABSTRACT

In this study, we submit a complex set of in-situ data collected by optical emission spectroscopy (OES) during the process of aluminum nitride (AlN) thin film. Changing the sputtering power and nitrogen(N2) flow rate, AlN film was deposited on Si substrate using a superior sputtering with a pulsed direct current (DC) method. The correlation between OES data and deposited film residual stress (tensile vs. compressive) associated with crystalline status by X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) measurements were investigated and established throughout the machine learning exercise. An important answer to know is whether the stress of the processing film is compressive or tensile. To answer this question, we can access as many optical spectra data as we need, record the data to generate a library, and exploit principal component analysis (PCA) to reduce complexity from complex data. After preprocessing through PCA, we demonstrated that we could apply standard artificial neural networks (ANNs), and we could obtain a machine learning classification method to distinguish the stress types of the AlN thin films obtained by analyzing XRD results and correlating with TEM microstructures. Combining PCA with ANNs, an accurate method for in-situ stress prediction and classification was created to solve the semiconductor process problems related to film property on deposited films more efficiently. Therefore, methods for machine learning-assisted classification can be further extended and applied to other semiconductors or related research of interest in the future.

13.
Plant Dis ; 105(12): 3858-3868, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34181437

ABSTRACT

Rice blast is a serious threat to global rice production. Large-scale and long-term cultivation of rice varieties with a single blast resistance gene usually leads to breakdown of resistance. To effectively control rice blast in Taiwan, marker-assisted backcrossing was conducted to develop monogenic lines carrying different blast resistance genes in the genetic background of an elite japonica rice cultivar, Kaohsiung 145 (KH145). Eleven International Rice Research Institute (IRRI)-bred blast-resistant lines (IRBLs) showing broad-spectrum resistance to local Pyricularia oryzae isolates were used as resistance donors. Sequencing analysis revealed that the recurrent parent, KH145, does not carry known resistance alleles at the target Pi2/9, Pik, Pita, and Ptr loci. For each IRBL × KH145 cross, we screened 21 to 370 (average of 108) plants per generation from the BC1F1 to BC3F1/BC4F1 generation. A total of 1,499 BC3F2/BC4F2 lines carrying homozygous resistance alleles were selected and self-crossed for four to six successive generations. The derived lines were also evaluated for background genotype using genotyping by sequencing, for blast resistance under artificial inoculation and natural infection conditions, and for agronomic performance in multiple field trials. In Chiayi and Taitung blast nurseries in 2018 to 2020, Pi2, Pi9, and Ptr conferred high resistance, Pi20 and Pik-h moderate resistance, and Pi1, Pi7, Pik-p, and Pik susceptibility to leaf blast; only Pi2, Pi9, and Ptr conferred effective resistance against panicle blast. The monogenic lines showed agronomic traits, yield, and grain quality similar to those of KH145, suggesting the potential of growing a mixture of lines to achieve durable resistance in the field.


Subject(s)
Disease Resistance/genetics , Magnaporthe , Oryza , Plant Diseases , Genotype , Oryza/genetics , Oryza/microbiology , Plant Breeding , Plant Diseases/genetics , Plant Diseases/microbiology
14.
Plants (Basel) ; 10(5)2021 Apr 22.
Article in English | MEDLINE | ID: mdl-33921967

ABSTRACT

Sphagnum peatmosses play an important part in water table management of many peatland ecosystems. Keeping the ecosystem saturated, they slow the breakdown of organic matter and release of greenhouse gases, facilitating peatland's function as a carbon sink rather than a carbon source. Although peatland monitoring and restoration programs have increased recently, there are few tools to quantify traits that Sphagnum species display in their ecosystems. Colony density is often described as an important determinant in the establishment and performance in Sphagnum but detailed evidence for this is limited. In this study, we describe an image analysis pipeline that accurately annotates Sphagnum capitula and estimates plant density using open access computer vision packages. The pipeline was validated using images of different Sphagnum species growing in different habitats, taken on different days and with different smartphones. The developed pipeline achieves high accuracy scores, and we demonstrate its utility by estimating colony densities in the field and detecting intra and inter-specific colony densities and their relationship with habitat. This tool will enable ecologists and conservationists to rapidly acquire accurate estimates of Sphagnum density in the field without the need of specialised equipment.

15.
PLoS One ; 16(4): e0250213, 2021.
Article in English | MEDLINE | ID: mdl-33882091

ABSTRACT

PURPOSE: To investigate the effectiveness of aerosol clearance using an aerosol box, aerosol bag, wall suction, and a high-efficiency particulate air (HEPA) filter evacuator to prevent aerosol transmission. METHODS: The flow field was visualized using three protective device settings (an aerosol box, and an aerosol bag with and without sealed working channels) and four suction settings (no suction, wall suction, and a HEPA filter evacuator at flow rates of 415 liters per minute [LPM] and 530 LPM). All 12 subgroups were compared with a no intervention group. The primary outcome, aerosol concentration, was measured at the head, trunk, and foot of a mannequin. RESULTS: The mean aerosol concentration was reduced at the head (p < 0.001) but increased at the feet (p = 0.005) with an aerosol box compared with no intervention. Non-sealed aerosol bags increased exposure at the head and trunk (both, p < 0.001). Sealed aerosol bags reduced aerosol concentration at the head, trunk, and foot of the mannequin (p < 0.001). A sealed aerosol bag alone, with wall suction, or with a HEPA filter evacuator reduced the aerosol concentration at the head by 7.15%, 36.61%, and 84.70%, respectively (99.9% confidence interval [CI]: -4.51-18.81, 27.48-45.73, and 78.99-90.40); trunk by 70.95%, 73.99%, and 91.59%, respectively (99.9% CI: 59.83-82.07, 52.64-95.33, and 87.51-95.66); and feet by 69.16%, 75.57%, and 92.30%, respectively (99.9% CI: 63.18-75.15, 69.76-81.37, and 88.18-96.42), compared with an aerosol box alone. CONCLUSIONS: As aerosols spread, an airtight container with sealed working channels is effective when combined with suction devices.


Subject(s)
Aerosols/chemistry , Dust/prevention & control , Suction/methods , Air Filters , Ventilators, Negative-Pressure
16.
Article in Chinese | MEDLINE | ID: mdl-32791646

ABSTRACT

Small cell neuroendocrine carcinoma(SCNC) of larynx is very rare. Primary small cell neuroendocrine carcinomas constitute less than 0.5% of all laryngeal cancers. Tumor can occur in any laryngeal subsite, while the supraglottis is the most common. Patients usually complaint with hoarseness and neck mass. The diagnosis of this kind of carcinomas relies strictly on histopathological examination and immunohistochemical testing. The prognosis of laryngeal SCNC is generally poor. Here, we report a case of a 55-year-old-male patient who presented with a poorly differentiated SCNC of the supraglottic larynx and neck mass.


Subject(s)
Carcinoma, Neuroendocrine , Carcinoma, Small Cell , Laryngeal Neoplasms , Larynx , Humans , Male , Middle Aged , Prognosis
17.
Chem Commun (Camb) ; 56(47): 6424-6427, 2020 Jun 11.
Article in English | MEDLINE | ID: mdl-32391823

ABSTRACT

Herein, the coordination-induced increase in the electron density of fused C6 rings in MOFs as high performance anode materials for Li+ ion batteries is described. Zn-PTCA is able to deliver a high specific capacity of 700 mA h g-1 at 50 mA g-1 and exhibits excellent cycle performance over 1100 cycles and good rate capability.

18.
Chemosphere ; 251: 126328, 2020 Jul.
Article in English | MEDLINE | ID: mdl-32169706

ABSTRACT

A total of 60 snow samples from 16 sites across northeastern China were collected from December 2017 to March 2018. The snow samples were analyzed for pH value, major water-soluble ions (Cl-, NO3-, SO42-, Na+, NH4+, K+, Ca2+, and Mg2+), and trace elements (Mn, Cr, Cd, Ni, Cu, Zn, Pb, As, and Fe). The results indicated that snow was slightly alkaline (mean pH value 7.54); Ca2+ and SO42- were the major ions, contributing up to 33.87% and 22.72% of the major ions, respectively; Pb was the dominant element, contributing up to 62.84% of the trace elements. Both the concentration of major ions and trace elements peaked in the middle or later period of the entire snow season. Enrichment factor (EF) analysis indicated that ions (NO3-, NH4+, and Ca2+) and trace elements (Pb, As, Cu, and Zn) were severely enriched by anthropogenic activities. Compared with previous studies, which sampled snow from the high altitude and latitude regions, the concentrations of most of the ions and trace elements in this study were found to be 1-3 and 1-4 orders of magnitude higher, respectively, indicating a threat to human health.


Subject(s)
Environmental Monitoring , Snow/chemistry , Trace Elements/analysis , China , Humans , Ions/analysis , Seasons
20.
Small ; 15(50): e1902377, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31721414

ABSTRACT

Lithium sulfide (Li2 S) is a promising cathode material with high capacity, which can be paired with nonlithium metal anodes such as silicon or tin so that the safety issues caused by the Li anode can be effectively avoided. However, the Li2 S full cell suffers from rapid capacity degradation due to the dissolution of intermediate polysulfides. Herein, a Li2 S/Si full cell is designed with a Li2 S cathode incorporated by titanium nitride (TiN) polysulfide immobilizer within parallel hollow carbon (PHC). This full cell delivers a high initial reversible capacity of 702 mAh gLi2S -1 (1007 mAh gsulfur -1 ) at 0.5 C rate and excellent cyclability with only 0.4% capacity fade per cycle over 200 cycles. The long cycle stability is ascribed to the strong polysulfide anchor effect of TiN and highly efficient electron/ion transport within the interconnected web-like architecture of PHC. Theoretical calculations, self-discharge measurements, and anode stability experiments further confirm the strong adsorption of polysulfides on the TiN surface. The present work demonstrates that the flexible Li2 S cathode and paired Si anode can be used to achieve highly efficient Li-S full cells.

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