Human-to-human contact plays a leading role in the transmission of infectious diseases, and the contact pattern between individuals has an important influence on the intensity and trend of disease ...transmission. In this paper, we define regular contacts and random contacts. Then, taking the COVID-19 outbreak in Yangzhou City, China as an example, we consider age heterogeneity, household structure and two contact patterns to establish discrete dynamic models with switching between daytime and nighttime to depict the transmission mechanism of COVID-19 in population. We studied the changes in the reproduction number with different age groups and household sizes at different stages. The effects of the proportion of two contacts patterns on reproduction number were also studied. Furthermore, taking the final size, the peak value of infected individuals in community and the peak value of quarantine infected individuals and nucleic acid test positive individuals as indicators, we evaluate the impact of the number of random contacts, the duration of the free transmission stage and summer vacation on the spread of the disease. The results show that a series of prevention and control measures taken by the Chinese government in response to the epidemic situation are reasonable and effective, and the young and middle-aged adults (aged 18-59) with household size of 6 have the strongest transmission ability. In addition, the results also indicate that increasing the proportion of random contact is beneficial to the control of the infectious disease in the phase with interventions. This work enriches the content of infectious disease modeling and provides theoretical guidance for the prevention and control of follow-up major infectious diseases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Water ages, SGD, and associated nutrients on different scales of Xiangshan Bay were evaluated using radium-based model.•SGD fluxes in XSB Channel and three inner embayments are at least 1–2 orders ...of magnitude higher than river discharge.•SGD is primarily regulated and modulated by ocean dynamics and anthropogenic activities.•SGD rates and associated nutrient rates in the XSB were comparable to those in other global mariculture regions.
Submarine groundwater discharge (SGD) is a predominant component of chemical fluxes in the solute budgets in coastal ecosystems because of its large flux and the corresponding concentrated constituents. A quantitative study regarding the mass balance model of 226Ra and 228Ra was performed to assess SGD and associated nutrient inputs in Xiangshan Bay (XSB), a typical Chinese aquaculture bay. Based on these mass balance models, the SGD rates in the XSB Channel were 8.9–13.2 cm d−1. The SGD rates in the three corresponding embayments were 3.5–3.7 cm d−1 in Embayment I, 5.6–5.8 cm d−1 in Embayment II, and 4.5–5.8 cm d−1 in Embayment III. Significant spatial variabilities in SGD rates were observed in the different XSB districts, reflecting that ocean dynamics and anthropogenic activities play significant roles at different scales. SGD-derived nutrient fluxes in XSB were the dominant sources of nutrient loading, and their magnitudes were approximately 1–2 orders larger than those of riverine input. SGD rates in the XSB Channel were approximately three times higher than those in the three embayments, but the SGD-derived nutrient rates in the XSB Channel were comparable with those in the three embayments, even significantly lower than that for NO3-N in the inner regions of the embayment. These results imply that aquaculture activities and urbanization jointly influence SGD. When combined with the results of other studies, our observations demonstrate the significant comprehensive effects of multiple factors on SGD, a critical but overlooked nutrient source.
Mangroves are blue carbon systems characterized by high soil carbon storage and sequestration. Soil carbon losses via groundwater or pore water pathways are potentially important yet poorly ...understood components of mangrove carbon budgets. Here we quantified submarine groundwater discharge (SGD) and associated dissolved inorganic carbon (DIC) and organic carbon (DOC) fluxes into a mangrove‐dominated tropical bay (Maowei Sea) using a radon (222Rn) mass balance model. The SGD fluxes in Maowei Sea were estimated to be 4.9 × 107 (0.36 ± 0.33 m/day) and 2.6 × 107 m3/day (0.20 ± 0.18 m/day) for the wet and dry seasons, respectively, implying that SGD may respond to precipitation. The SGD‐derived DIC and DOC fluxes (mol·m−2·day−1) in the wet season (DIC: 0.70 ± 0.82; DOC: 0.31 ± 0.30) were higher than those in the dry season (DIC: 0.25 ± 0.24; DOC: 0.25 ± 0.23). These SGD‐derived carbon fluxes exceed local river inputs and constituted >70% of the total DIC and DOC input into the bay. If scaled up to the global weighted mangrove area in combination with data from other 32 study sites, carbon fluxes via SGD into mangroves may be equivalent to 29–48% of the global riverine input into the ocean. Therefore, we suggest that SGD is a major component of coastal carbon budgets and that accounting for SGD helps to reduce uncertainties in mangrove blue carbon budgets.
Plain Language Summary
Mangrove soils sequester large amounts of carbon, but little is known on the loss of carbon via groundwater pathways. Here we quantified submarine groundwater discharge using radon and related dissolved inorganic and organic carbon fluxes in a mangrove‐dominated tropical bay in China (Maowei Sea). Combining our results with literature data revealed that groundwater fluxes in mangroves are significant and should be considered in blue carbon assessments.
Key Points
SGD‐derived carbon fluxes were estimated for a typical mangrove‐dominated bay
DIC and DOC fluxes via SGD exceeded river inputs into Maowei Sea, China
SGD‐derived carbon fluxes seem to be important in global blue carbon budgets
Display omitted
•Coprecipitation had weaker selective fractionation than adsorption processes.•Ferrihydrite selectively adsorbed a large amount of aliphatics.•Selectivity coprecipitation of ...components of OM depended on the OC/Fe ratios.•Aromatic compounds were prone to be coprecipitated in a high ionic matrix.•Ferrihydrite associated with more N-compounds in mangrove OM than salt marsh OM.
The association of organic matter (OM) with iron (Fe) is a critical mechanism to preserve OM in intertidal coastal ecosystems such as salt marshes and mangroves. The present study aimed to investigate the influence of the organic carbon to Fe molar ratio (OC/Fe), ionic strength, and OM composition on Fe-OM association. Fe-OM was prepared using humic acids extracted from salt marsh and mangrove sediments by the adsorption process in the OC/Fe molar ratios of 0.01–1.0 and by the coprecipitation process in the OC/Fe molar ratios of 0.1–9.9. Sample properties were studied by X-ray diffraction, scanning electron microscopy, ultraviolet–visible spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, three-dimensional fluorescence excitation emission matrix spectroscopy, and pyrolysis–gas chromatography/mass spectrometry. The results showed that selective associations of OM components with ferrihydrite were affected by the association mode (e.g., adsorption and coprecipitation), OC/Fe molar ratio, OM composition and ionic strength. Abundant aliphatic compounds could be adsorbed on ferrihydrite. Moreover, ferrihydrite was prone to preserve humic-like fluorescent components through the adsorption process. The protein-like fluorescent components and aliphatic compounds had high affinity for ferrihydrite during coprecipitation with low OC/Fe molar ratios. An increase in the OC/Fe molar ratio resulted in coprecipitation of aromatic compounds with ferrihydrite. Salinity-induced flocculation caused more amount of aromatic and polycyclic aromatic compounds to associate with ferrihydrite during the coprecipitation process. Compared to the salt marsh OM, more N-compounds and less aliphatic compounds in the mangrove OM were coprecipitated with ferrihydrite. This study provided important insights into the mechanisms of OM preservation with ferrihydrite in tidal wetland ecosystems.
A new type of epileptogenic tumor, the polymorphous low-grade neuroepithelial tumor of the young (PLNTY) was firstly reported by Jason T. Huse et al. at 2016. After that, only 1 case of PLNTY was ...reported by article. The radiological characteristics of PLNTY have not been concluded. The objective of our study was to report 3 cases of PLNTYs in details and to analyze the image characteristics and genetic alterations of PLNTYs by reviewing our cases and articles.
There were 3 cases diagnosed as PLNTY by pathology in our hospital during the last 10 years, with the average age of 15. They were all suffered from different degrees of epilepsy. All of them underwent magnetic resonance (MR) imaging and 2 of them underwent computer tomography (CT) imaging. The PLNTYs are all appearing as a solid or solid-cystic cortical mass with little mass effect and unclear boundary with normal brain tissue. They are all shown as hyperintensity in T2WI and iso-/hypointensity in T1WI with slight or no enhancement after contract enhanced in MR imaging. The "salt and pepper sign" in T2WI and grit calcification in CT images might be specific characteristics of PLNTY. All of them recovered after excision of the tumors. The gene tests revealed fibroblast growth factor receptors 3 (FGFR3)-TACC3 fusion and FGFR3 amplification in one case, and the B-Raf proto-oncogene (BRAF) V600E mutation in another case.
In the image, the partial ill-marginated cortical mass with "salt and pepper sign" in T2WI or grit calcification in CT imaging might be the typical imaging characteristics of PLNTY. We also prove that the BRAF V600E mutation as well as the FGFR2 and FGFR3 have a close relationship with PLNTY.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An amplified electrochemical biosensing scheme is described for lead(II) ions. It is making use of DNAzyme-assisted target recycling and catalytic hairpin assembly (CHA). The hairpin strand ...(substrate probe for the Pb
2+
-based DNAzyme; referred to as SP) is composed of trigger probe (TP) and a capture probe 1 attached to gold nanoparticles (AuNP). In the presence of the enzyme probe that partially hybridizes with SP, the introduction of Pb
2+
triggers target recycling and drives the highly amplified translation of target Pb(II) to TP. The CHA reaction is further initiated by TP. The modified AuNP act as the connecting unit, and this leads to the formation of a 3D DNA-AuNP network on the electrode (which is the third amplification step). It can bind the positively charged redox mediator RuHex via electrostatic interaction for electrochemical detection. This biosensor has a low detection limit (95 pM) and any analytical range that covers the 100 pM to 5 μM Pb(II) concentration range. It is selective over other divalent metal ions. It was applied to the determination of Pb
2+
in spiked real-world samples.
Graphical abstract
Schematic presentation of the electrochemical biosensor. The triply amplified electrochemical assay is based on the use of DNAzyme-assisted target recycling with catalytic hairpin assembly (CHA) reaction for sensitive and selective determination of lead ion (Pb
2+
). AuNP: gold nanoparticles; SP: substrate probe; EP: enzyme probe.
Variability in iron species in marine deposits are excellent geochemical archives for exploring variations in redox conditions during early diagenesis and seepage dynamics over time. Two sediment ...cores (DS07 and DS08) were collected in the Jiulong Methane Reef, a typical cold seep site that is located in the South China Sea (SCS), and analyzed for iron species using Mössbauer spectrometry and magnetic procedures. Excluding the surface layer (0-10 cm) in DS07, Fe2+/Fe3+ ratios indicated that core sediments were under anoxic conditions. The Fe2+/Fe3+ and frequency-dependent susceptibility (χfd) at this site were higher while the total organic matter content (TOC) and magnetic susceptibility (χ) were significantly lower at approximately 170 cm depth. Combined with chromium reducible sulfur (CRS), Fe/Al and sulfur to organic content (S/C) ratios suggested that there was a sulfate-methane transition zone (SMTZ) at approximately 170 cm. Moreover, thermomagnetic analyses indicated that magnetite was the dominant ferrimagnetic mineral at 21–23 cm, 165–185 cm, 213–233 cm and 285–295 cm depths, however, magnetite content was relatively lower between the 165 and 185 cm depth, which suggested that magnetite had been largely transformed to paramagnetic iron minerals during the anaerobic oxidation of methane (AOM) process. The DS08 sediment core was also mostly anoxic , however, no obvious methane seepage activity was observed because the maximum values of Fe2+/Fe3+, Fe/Al, CRS, S/C and the minimum values of TOC and χ did not simultaneously occur at the same depth. The study revealed that the speciation of Fe in sediment cores varied under different redox conditions which was of interest when utilizing iron speciation and magnetic minerals as indicators of historical environmental conditions and seepage activities.
Display omitted
•Fe species were characterized by Mössbauer spectra and magnetic analysis.•DS07 and DS08 were almost in reducing condition except the surface sediment.•Transient methane seepage occurred around 170 cm in DS07.•There was no obvious SMTZ in DS08.•Fe species could be used to trace redox conditions, especially for CH4 seepage.
Seasonal molecular changes in dissolved organic matter (DOM) isolated from Tai Lake (Taihu) both during (June) and following (November) an algal bloom event in 2007 were characterized by nuclear ...magnetic resonance spectroscopy (NMR) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Considerable biosignatures were present in summer DOM, yet with a near absence of algal extract compounds. Extensive molecular alteration resulting from multistep and massively parallel biotic and subordinated abiotic transformations of algal biomass to DOM included loss and synthesis of carbohydrates, fundamental changes of aromatic compounds and progressive formation of carboxyl-rich alicyclic compounds (CRAM). The DOM transformation from summer to fall resulted in smaller molecules, increased abundance of CHNO continuous molecular series and overall molecular diversity. Analysis of MS-derived compositional networks placed summer DOM in-between the algal extract and fall DOM. Metabolic pathway annotation by means of high-resolution mass analysis provided a wide range of pathways associated with secondary metabolites in DOM and more basic ones like carbohydrate metabolism characteristic of algal extract compounds. Overall, the time-dependent molecular signature of Taihu DOM was likely dominated by microbial metabolism rather than abiotic chemical transformations. Results from this study indicate that high-resolution organic structural spectroscopy resolves meaningful structural detail out of complex environmental mixtures and has the potential to contribute significantly to future functional biodiversity studies.
210Po and 210Pb are well-known tracer pairs for some biomass and chemical processes in the marine system. In this study, 210Po and 210Pb were analyzed in surface seawater collected from the East ...China Sea (ECS), in atmospheric deposition, and in riverine input water collected along the ECS coast. The atmospheric fallouts of 210Po and 210Pb were higher in the dry season, due to the arrival of storm dust from the northwestern region of China. In the riverine input water, the particulate 210Po and 210Pb dominated (corresponding to 33–94% and 50–92% of the total, respectively), especially during the flood season. In the surface seawaters, the percentage of particulate 210Po (17–85%) was generally greater than that of 210Pb (10–76%). Additionally, in the Changjiang Estuary, log Kd(Po) and log Kd(Pb) were negatively correlated with log suspended particulate matter (SPM) (R = 0.71, P = 0.013 for Po, R = 0.67, P = 0.019 for Pb). 210Pb showed a stronger “particle effect” than 210Po when SPM <1.00 mg L−1, and vice versa when SPM >1.00 mg L−1. The deficit of 210Po relative to 210Pb gradually decreased from the Changjiang Diluted Water, to the Shelf Merged Water and the Taiwan Warm Current Water. The mass balance of 210Po and 210Pb in the water column of the estuary indicated that the Changjiang River was the dominating input source (providing 91% and 88% of the 210Po and 210Pb, respectively); meanwhile, the shelf export was the dominating output source (accounting for 68% and 78% of the 210Po and 210Pb, respectively).
•Particulate 210Po and 210Pb were dominant in the high-turbidity surface water of ECS.•The deficiency of 210Po relative to 210Pb decreased with offshore water masses.•210Pb showed a stronger “particle effect” than 210Po when SPM < 1.00 mg L−1, and vice versa when SPM > 1.00 mg L−1.•The predominant source and sink of 210Po and 210Pb in the estuary are the river input and shelf report.
To gain a better understanding of the chemical structural composition and reactivity of sedimentary organic matter in coastal environments, the properties of sedimentary humic substances (HSs) ...isolated from contrasting coastal marine environments (i.e., salt marsh estuary, continental shelf, and continental slope) in China were investigated and compared. The complementary analytical approaches employed included elemental analysis, cross polarization magic angle spinning (CP/MAS)-
13
C nuclear magnetic resonance, pyrolysis-gas chromatography–mass spectrometry, and potentiometric titrations. The results indicate that HSs isolated from the salt marsh site in the Changjiang Estuary, which is strongly influenced by terrestrial river inputs, had the highest content of lignin-derived components, such as phenols and alkyl phenols, and acidic functional groups; HSs from the continental slope site in the South China Sea, which mainly originated from the inputs of marine algae and planktons, contained the highest level of aliphatic compounds, carbohydrates, and nitrogen-containing compounds; however, HSs from the continental shelf site in the East China Sea presented a mixture of both land and marine properties due to the influence of the two sources. Humic acids were found to contain comparatively more highly branched, long-chain aliphatic components but fewer oxygen-containing functional groups, such as carboxyl groups, and fewer sulfur-containing compounds than their fulvic acid counterparts. The total concentrations of proton binding sites and the structural characteristics of the studied HSs may provide insights into the migration and fate of HS-bound contaminants, such as heavy metals and organic pollutants, in coastal marine systems.
PDF
