Quantitative identification of nitrate (NO3−-N) sources is critical to the control of nonpoint source nitrogen pollution in an agricultural watershed. Combined with water quality monitoring, we ...adopted the environmental isotope (δD-H2O, δ18O-H2O, δ15N-NO3−, and δ18O-NO3−) analysis and the Markov Chain Monte Carlo (MCMC) mixing model to determine the proportions of riverine NO3−-N inputs from four potential NO3−-N sources, namely, atmospheric deposition (AD), chemical nitrogen fertilizer (NF), soil nitrogen (SN), and manure and sewage (M&S), in the ChangLe River watershed of eastern China. Results showed that NO3−-N was the main form of nitrogen in this watershed, accounting for approximately 74% of the total nitrogen concentration. A strong hydraulic interaction existed between the surface and groundwater for NO3−-N pollution. The variations of the isotopic composition in NO3−-N suggested that microbial nitrification was the dominant nitrogen transformation process in surface water, whereas significant denitrification was observed in groundwater. MCMC mixing model outputs revealed that M&S was the predominant contributor to riverine NO3−-N pollution (contributing 41.8% on average), followed by SN (34.0%), NF (21.9%), and AD (2.3%) sources. Finally, we constructed an uncertainty index, UI90, to quantitatively characterize the uncertainties inherent in NO3−-N source apportionment and discussed the reasons behind the uncertainties.
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•The stable isotope analysis and MCMC model were used to identify the nitrate pollution sources.•Nitrification dominated the nitrogen transformation in the surface water of the watershed.•The denitrification process was observed in groundwater.•Mean 41.8%, 33.9% and 21.9% of the nitrate were contributed from M&S, SN and NF, respectively.•We constructed a new index to characterize the uncertainties of the nitrate sources identification.
The stable isotope analysis and MCMC model were adopted to quantify the nitrate pollution sources in an agricultural watershed, and a new index UI90 was used to characterize their uncertainties.
Microplastics (MPs) in marine and terrestrial environments have been intensively studied, but the dynamics of airborne MPs remains limited. Existing studies on atmospheric MPs are mostly derived from ...collection of atmospheric deposition, whereas direct measurements of airborne MPs are scarce. However, the abundance of airborne MPs is more relevant for evaluating human inhalation exposure risk. Herein, airborne MPs in indoor and outdoor environments from urban and rural areas of a coastal city in eastern China were investigated. MP concentrations (mean±SD) in indoor air (1583 ± 1180 n/m3) were an order of magnitude higher than outdoor air (189 ± 85 n/m3), and airborne MP concentrations in urban areas (224 ± 70 n/m3) were higher than rural areas (101 ± 47 n/m3). MPs smaller than 100 µm dominated airborne MPs, and the predominant shape of airborne MPs was fragments, as opposed to fibers. The larger MP size fractions contained a higher proportion of fibers, whereas the smaller size fractions were nearly exclusively composed of fragments. The health risk caused by ubiquitous airborne MPs should not be discounted as the maximum annual outdoor exposure of airborne MPs can reach 1 million/year, while indoor exposure may be even higher due to higher indoor airborne MP concentrations.
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•High MP abundance was found in indoor (1583 ± 1180 n/m3) and outdoor (189 ± 85 n/m3) air.•MPs smaller than 100 µm were dominant in both indoor and outdoor air samples.•Fragments were dominant compared to fibers in all samples.•Fibers dominate large airborne MPs whereas fragments dominate small airborne MPs.•Maximum annual outdoor inhalation exposure of airborne MPs can reach 1 million/year.
We conducted a meta-analysis on the impact of microRNA-133a (miR-133a) on digestive system cancers, and verified the results through The Cancer Genome Atlas (TCGA). Relevant studies were searched in ...English and Chinese database and meta-analysis was performed using Stata 12.0. The corresponding information of miR-133a and digestive system cancers were obtained from TCGA database and analysis was performed using SPSS. Increased miR-133a expression was linked with favorable overall survival (OS) in digestive system cancers (HR = 0.539, 95% CI: 0.416–0.698,
P
< 0.001), digestive tract cancers (HR =0.558, 95% CI: 0.406–0.767,
P
< 0.001), esophageal squamous cell carcinoma (ESCC) (HR = 0.427, 95% CI: 0.265–0.690,
P
= 0.001) and gastric cancer (HR = 0.541, 95% CI: 0.385–0.761,
P
< 0.001). The expression of miR-133a was significantly lower in cancer tissue compared with adjacent tissue for ESCC (
P
< 0.001), gastric cancer (
P
< 0.001), colorectal cancer (
P
< 0.001) and hepatocellular carcinoma (
P
= 0.002). Meanwhile, the area under the ROC curve (AUC) value for miR-133a was 0.836, 0.888, and 0.99 in ESCC, gastric cancer and colorectal cancer. MiR-133a is a tumor suppressor with prognostic and diagnostic values for digestive system cancers. High miR-133a expression was associated with better prognosis and less adverse clinicopathological parameters. More research should be performed to test these findings.
Herein we have developed a reversible hydrogen–deuterium exchange reaction of nonactivated olefins. By using EtOCS2K as a mediator, the H/D exchange reaction was realized through repeated addition ...and elimination reactions, demonstrating reversible H/D exchange between ordinary olefins and deuterated olefins. Using the lowest cost D2O without precious metal catalysts and ligands, a broad spectrum of compatibility of functional groups was achieved.
Reliable measurements of the kinetics of β → α allotropic transformation in Sn-based solder underlie the design and development of advanced interconnects for low-temperature electronics. In this ...paper, a highly-accessible and buoyancy-based method, but different from common dilatometry, was developed to consistently detect a change of the transformed fraction in bulk βSn plates (10 × 10 × 1mm) with time at −20, −40, and −60 °C. Due to the concurrent effects of undercooling temperature and interfacial atomic diffusion, the β → α transformation in Sn plates at −40 °C proceeded most rapidly up to around 70% αSn fraction after 168 h. The transformed fraction versus time curves yielded excellent fits to the classic Johnson-Mehl-Avrami-Kolmogorov model with a constant nucleation rate during transformation process (Avrami exponent, n of 4). Addition of nucleation agent accelerated the transformation by shortening the incubation period, but the nucleation rate decreased to zero in the following transformation (n = 3). Furthermore, coarsening grain size depressed β → α transformation and led to the saturation of nucleation sites in the vicinity of half transformation (n decreasing from 4 to 2). The simple, convenient, and reliable method proposed showed high sensitivity with detection limits of about 2%, and it could be a promising approach to study and predict solid-state phase transformation kinetics.
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•An accessible approach was designed to determine the kinetics of β→α allotropic transformation of bulk Sn plates.•The method proposed showed high sensitivity towards β→α transition in bulk Sn with detection limits of less than 2%.•The kinetics of β→α transformation were found to follow Johnson-Mehl-Avrami-Kolmogorov model.•The Avrami exponent varied according to a variety of factors.
The effect of the modification treatment on the refinement of primary carbides and wear resistance of 35% Cr-4.0% C hypereutectic high chromium cast iron (HHCCI) was investigated using the ...first-principles calculations, XRD, SEM, TEM, hardness tests, and wear tests. The addition of N elements to HHCCI refined the size of the M7C3 primary carbide from 13.25 ± 0.72 μm to 11.67 ± 0.33 μm under the effect of adsorption refinement. When the compound modification elements (N + Ti + V + RE-Mg) were added, the combination of adsorption refinement and heterogeneous nucleation refinement significantly reduced the carbide size to 5.35 ± 0.15 μm. The refinement of the M7C3 primary carbide can be attributed to two components: 1) the refinement of the heterogeneous nucleation of TiC and VC. 2) the combination of N, Ti, and V with the M7C3 preferred growth surface (0001) resulting in the refinement by adsorption and reduce the size of the primary carbide. The hypereutectic high chromium cast iron after the compound modification exhibited excellent wear resistance. Under dry sliding wear condition, Compared with the unmodified sample, the wear resistance increased by 75%. Under corrosive wear conditions, the wear resistance is increased by 98.1%.
Gravity‐induced drainage is one of the main destabilizing mechanisms for soap bubbles and foams. Here we show that solely through acoustic levitation without introducing any chemical stabilizers, ...liquid drainage in the bubble film can be completely inhibited, therefore leading to a significant enhancement of bubble lifetime by more than two orders of magnitude and enabling the bubble to survive puncturing by a needle. Based on sound simulation and force analysis, it has been found that acoustic radiation force, exerted on both the inner and outer surfaces of the levitated bubble, acts in opposite directions, thus providing a squeezing effect to the bubble film. The hydrostatic pressure that induces drainage has been balanced by the acoustic radiation pressure exerted on both sides of the film, which is at the origin of the sound stabilization mechanism. This study provides new insights into the interplay between sound and soap bubbles or films, thus stimulating a wide range of fundamental research concerning bubble films and expanding their applications in bio/chemical reactors.
In this study, we report that, for the first time, extraordinary stability of liquid bubbles can be obtained from acoustic levitation. The lifetime of bubbles can be prolonged by more than two orders of magnitude owing to the stabilization by the sound field, for instance, a pure water bubble can remain unburst for about 8 min. This suggests the bubble can be stabilized without the presence of any surfactant or solid particles, thus preventing contamination by these materials. The bubbles can be kept both stable and clean, which is highly desired for the applications of these bubbles as bio/chemical reactors.
Abstract
Low temperature nanojoining and high temperature service in the microelectronic packaging technology has received much focused attention. Here, we suggest a facile thermal decomposition ...method for preparation of Cu10Sn3 nanoparticles (NPs) with high bulk melting point (640 °C) by using common organic salts, oleylamine (OLA), and oleic acid (OA). The uniform and dense sintered Cu/Cu10Sn3/Cu joints can obtain at 300 °C, 10 MPa, 20 min, which presents the average shear strength of 25.1 MPa. In addition, the interdiffusion of Sn and Cu atoms at interface between the sintered Cu10Sn3 layer and Cu makes the interface a metallurgical bonding. This sintered Cu/Cu10Sn3/Cu joints can provide a new interconnect material and technology for high-power device package.
•Cu10Sn3 nanoparticles were synthesized by a one-step thermal decomposition method.•The Cu10Sn3 possesses good oxidation resistance under atmospheric environment.•The acquired full-Cu10Sn3 joints have high enough bonding strength (25.1 MPa) with low resistivity (19.31 μΩ cm).
Bubbles in air are ephemeral because of gravity‐induced drainage and liquid evaporation, which severely limits their applications, especially as intriguing bio/chemical reactors. In this work, a new ...approach using acoustic levitation combined with controlled liquid compensation to stabilize bubbles is proposed. Due to the suppression of drainage by sound field and prevention of capillary waves by liquid compensation, the bubbles can remain stable and intact permanently. It has been found that the acoustically levitated bubble shows a significantly enhanced particle adsorption ability because of the oscillation of the bubble and the presence of internal acoustic streaming. The results shed light on the development of novel air‐purification techniques without consuming any solid filters.
This work reports a new approach to stabilize bubbles that by using acoustic levitation combined with controlled liquid compensation the bubbles can remain intact permanently. The acoustically levitated bubble shows a significantly enhanced particle adsorption ability which shed light on the developing of novel air‐purification techniques without consuming of any solid filters.
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