A simple and label-free colorimetric method for cadmium ions (Cd2+) detection using unmodified gold nanoparticles (AuNPs) is reported. The unmodified AuNPs easily aggregate in a high concentration of ...NaCl solution, but the presence of glutathione (GSH) can prevent the salt-induced aggregation of AuNPs. When Cd2+ is added to the stable mixture of AuNPs, GSH, and NaCl, Cd2+ can coordinate with 4× GSH as a spherical shaped complex, which decreases the amount of free GSH on the surface of gold nanoparticles to weaken the stability of AuNPs, and AuNPs will easily aggregate in high-salt conditions. On the basis of the mechanism, we design a simple, label-free colorimetric method using AuNPs accompanied by GSH in a high-salt environment to detect Cd2+ in water and digested rice samples.
Chronic stress is known to promote inflammatory bowel disease (IBD), but the underlying mechanism remains largely unresolved. Here, we found chronic stress to sensitize mice to dextran sulfate sodium ...(DSS)-induced colitis; to increase the infiltration of B cells, neutrophils, and proinflammatory ly6Chi macrophages in colonic lamina propria; and to present with decreased thymus and mesenteric lymph node (MLN) coefficients. Circulating total white blood cells were significantly increased after stress, and the proportion of MLN-associated immune cells were largely changed. Results showed a marked activation of IL-6/STAT3 signaling by stress. The detrimental action of stress was not terminated in IL-6−/− mice. Interestingly, the composition of gut microbiota was dramatically changed after stress, with expansion of inflammation-promoting bacteria. Furthermore, results showed stress-induced deficient expression of mucin-2 and lysozyme, which may contribute to the disorder of gut microbiota. Of note is that, in the case of cohousing, the stress-induced immune reaction and decreased body weight were abrogated, and transferred gut microbiota from stressed mice to control mice was sufficient to facilitate DSS-induced colitis. The important role of gut microbiota was further reinforced by broad-spectrum antibiotic treatment. Taken together, our results reveal that chronic stress disturbs gut microbiota, triggering immune system response and facilitating DSS-induced colitis.
•A VPOSR framework model was proposed.•The water environment carrying capacity of Beijing from 2008 to 2016 were evaluated.•The key factors affecting the water environment carrying capacity were ...identified.•The correlation degree between each indicator and carrying capacity was explored.•The level of coupling coordination between subsystems was explored.
In order to gain an in-depth understanding of the change of urban water environment carrying capacity (WECC), we proposed a framework system of VPOSR (vigor, pressure, organization, state and resilience subsystem), which was used to construct an evaluation index system for urban WECC. The coefficient of variation grey correlation method was employed to analyze the urban WECC of each subsystem of Beijing, China from year 2008 to 2016. The coupling coordination degree of each subsystem were calculated. The results show that: (1) The evaluation index value of WECC in Beijing is on the rise from 0.3560 in 2008 to 0.7877 in 2016, which suggests that the index of WECC of Beijing is improving, and the social and economic development is within an affordable range of the water environment. (2) The rate of ecological water usage, the proportion of energy conservation and environmental protection in local financial expenditure and the per capita water resources are the top three indicators with great impact on WECC. (3) The correlation degree index of vigor subsystem, pressure subsystem, organization subsystem, state subsystem, and resilience subsystem with water environment carrying capacity system are 0.0958, 0.1169, 0.0252, 0.0328 and 0.2962 respectively. The subsystem with strong correlation with water environment is resilience subsystem, followed by pressure subsystem. (4) According to the index distribution of coordination degree, the coordination degree level is between 0.4032 and 0.4458, and the coupling degree of each subsystem is above 0.8, which belong to the high coupling level.
Causality bounds on scalar-tensor EFTs Hong, Dong-Yu; Wang, Zhuo-Hui; Zhou, Shuang-Yong
The journal of high energy physics,
10/2023, Letnik:
2023, Številka:
10
Journal Article
Recenzirano
Odprti dostop
A
bstract
We compute the causality/positivity bounds on the Wilson coefficients of scalar-tensor effective field theories. Two-sided bounds are obtained by extracting IR information from UV physics ...via dispersion relations of scattering amplitudes, making use of the full crossing symmetry. The graviton
t
-channel pole is carefully treated in the numerical optimization, taking into account the constraints with fixed impact parameters. It is shown that the typical sizes of the Wilson coefficients can be estimated by simply inspecting the dispersion relations. We carve out sharp bounds on the leading coefficients, particularly, the scalar-Gauss-Bonnet couplings, and discuss how some bounds vary with the leading (
∂ϕ
)
4
coefficient and as well as phenomenological implications of the causality bounds.
Herein, we show that the combination of the Birch reduction of readily available anisole derivatives and the catalytic asymmetric inverse‐electron‐demand Diels–Alder reaction of 2‐pyrones can serve ...as a powerful platform for the diverse synthesis of synthetically important cis‐decalin scaffolds. Enabled by a well‐modified chiral bis(oxazoline) ligand/CuII complex, a wide range of polysubstituted cis‐decalin scaffolds with up to six contiguous stereocenters were generated efficiently. The synthetic potential of this method is demonstrated by the concise synthesis of the sesquiterpene (+)‐occidentalol and a key intermediate for seven triterpenes. Mechanistic studies suggest the 1,3‐cyclohexadienes formed in situ are the key intermediates, and efficient kinetic resolution occurs when C2‐ and/or C3‐substituted 1,4‐cyclohexadienes are utilized as substrates. DFT calculations elucidated that the Diels–Alder reaction proceeds in a stepwise fashion and revealed the origins of the stereoselectivities.
Asymmetric synthesis of highly functionalized chiral cis‐decalins was realized by merging Birch reduction and a tandem olefin migration/asymmetric IEDDA reaction. Up to six contiguous and two quaternary stereocenters could be formed in one step by efficient kinetic resolution. The synthetic value of the approach is illustrated by the concise total synthesis of (+)‐occidentalol and the synthesis of a key intermediate for seven triterpenes.
•The 8μm nitrided layer was produced on the surface of AISI 316L stainless steel by plasma nitrided at high temperatures (540°C) within 1h.•The nitrided layer consisted of nitrogen expanded austenite ...and possibly a small amount of free-CrN and iron nitrides.•It could critically reduce processing time compared with low temperature nitriding.•High temperature plasma nitriding could improve pitting corrosion resistance of the substrate in 3.5% NaCl solution.
It has generally been believed that the formation of the S phase or expanded austenite γN with enough thickness depends on the temperature (lower than 480°C) and duration of the process. In this work, we attempt to produce nitrogen expanded austenite layer at high temperature in short time. Nitriding of AISI 316L austenitic stainless steel was carried out at high temperatures (>520°C) for times ranging from 5 to 120min. The microstructures, chemical composition, the thickness and the morphology of the nitrided layer, as well as its surface hardness, were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, optical microscopy, scanning electron microscopy, and microhardness tester. The corrosion properties of the untreated and nitrided samples were evaluated using anodic polarization tests in 3.5% NaCl solution. The results confirmed that nitrided layer was shown to consist of γN and a small amount of free-CrN and iron nitrides. High temperature plasma nitriding not only increased the surface hardness but also improved the corrosion resistance of the austenitic stainless steel, and it can critically reduce processing time compared with low temperature nitriding.
The use of extracellular vesicles, specifically exosomes, as carriers of biomarkers in extracellular spaces has been well demonstrated. Despite their promising potential, the use of exosomes in the ...clinical setting is restricted due to the lack of standardization in exosome isolation and analysis methods. The purpose of this review is to not only introduce the different types of extracellular vesicles but also to summarize their differences and similarities, and discuss different methods of exosome isolation and analysis currently used. A thorough understanding of the isolation and analysis methods currently being used could lead to some standardization in the field of exosomal research, allowing the use of exosomes in the clinical setting to become a reality.
A simple, cost-effective and rapid colorimetric method for any or all of Hg
2+, Pb
2+ and Cu
2+ detection using papain-functionalized gold nanoparticles (P-AuNPs) has been developed. Papain is a ...protein with seven cystein residues, which can selectively bind with Hg
2+, Pb
2+ and Cu
2+. We functionalized gold nanoparticles with papain. The P-AuNPs could be used to simultaneously detect Hg
2+, Pb
2+ and Cu
2+, and showed different responses to the three ions in an aqueous solution based on the aggregation-induced color change of gold nanoparticles. The P-AuNPs displayed the most obvious response to mercury ions in water in contrast to lead and copper ions, and the real water sample analysis verified the conclusion. The sensitivity of the detection system was influenced by the pH of the P-AuNPs solution, the concentration of P-AuNPs and the size of gold nanoparticles, and we found that larger gold nanoparticles contributed to more sensitive results. The detection system can detect as low as 200
nM Hg
2+, Pb
2+ or Cu
2+ using 42
nm gold nanoparticles. We expect our approach to have wide-ranging applications in the developing region for monitoring water quality in some areas.
This report presents a highly sensitive, rhodamine B-covered gold nanoparticle (RB-AuNP) -based assay with dual readouts (colorimetric and fluorometric) for detecting organophosphorus and carbamate ...pesticides in complex solutions. The detection mechanism is based on the fact that these pesticides can inhibit the activity of acetylcholinesterase (AChE), thus preventing the generation of thiocholine (which turns the RB-AuNP solutions blue and unquenches the fluorescence of RB simultaneously). The color of the RB-AuNP solution remains red and the fluorescence of RB remains quenched. By use of this dual-readout assay, the lowest detectable concentrations for several kinds of pesticides including carbaryl, diazinon, malathion, and phorate were measured to be 0.1, 0.1, 0.3, and 1 μg/L, respectively, all of which are much lower than the maximum residue limits (MRL) as reported in the European Union pesticides database as well as those from the U.S. Department Agriculture (USDA). This assay allows detection of pesticides in real samples such as agricultural products and river water. The results in detecting pesticide residues collected from food samples via this method agree well with those from high-performance liquid chromatography (HPLC). This simple assay is therefore suitable for sensing pesticides in complex samples, especially in combination with other portable platforms.
A dispersion‐dominated chromogenic strategy for glutathione sensing is developed. Glutathione prevents the aggregation of arginine‐modified gold nanoparticles via mercury–thiol interaction, which ...allows for glutathione sensing at the nanomolar level (10.9 × 10−9
m) with facile operation and naked‐eye readout.
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