•Dissolved black carbon (DBC) was first determined in the western Arctic Ocean and Bering Sea.•Freshwater dominants the spatial pattern of DBC, river water and sea-ice meltwater show contrasting ...effect on DBC content.•The shelves represent the main removal sites of riverine DBC and determine DBC reaching the open oceans.
In the Arctic, large amounts of black carbon (BC) are released into river water and transported to the oceans as dissolved BC (DBC). However, the cycling and fate of DBC in the ocean is poorly understood. Here, DBC, dissolved organic carbon (DOC), absorbance, and δ18O were analyzed to examine the spatial characteristics and removal of DBC in the western Arctic Ocean and the Bering Sea during the boreal summer. DBC concentrations ranged from 0.67 to 4.18 μmol-C L−1. In the sea-ice free regions, high DBC and DOC concentrations and a254 values corresponded to high δ18O-derived meteoric water contents, indicating that river discharge dominated their spatial patterns. By contrast, sea-ice meltwater (SIM) appeared to dilute DBC and DOC in SIM impacted waters (SIM > 3.5%). The departure of DBC from conservative mixing lines suggested that 47–84% of riverine DBC was removed over the shelves with 7–23% transported to the upper Canada Basin. These results suggest that shelf regions are crucial sites for riverine DBC removal that modulate the delivery of DBC to the open Arctic Ocean.
Abstract
Single-atom catalysts (SACs) have been applied in many fields due to their superior catalytic performance. Because of the unique properties of the single-atom-site, using the single atoms as ...catalysts to synthesize SACs is promising. In this work, we have successfully achieved Co
1
SAC using Pt
1
atoms as catalysts. More importantly, this synthesis strategy can be extended to achieve Fe and Ni SACs as well. X-ray absorption spectroscopy (XAS) results demonstrate that the achieved Fe, Co, and Ni SACs are in a M
1
-pyrrolic N
4
(M= Fe, Co, and Ni) structure. Density functional theory (DFT) studies show that the Co(Cp)
2
dissociation is enhanced by Pt
1
atoms, thus leading to the formation of Co
1
atoms instead of nanoparticles. These SACs are also evaluated under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and the nature of active sites under HER are unveiled by the
operando
XAS studies. These new findings extend the application fields of SACs to catalytic fabrication methodology, which is promising for the rational design of advanced SACs.
A hybrid simplex artificial bee colony algorithm (HSABCA) which combines Nelder–Mead simplex method with artificial bee colony algorithm (ABCA) is proposed for inverse analysis problems. The proposed ...algorithm is applied to parameter identification of concrete dam-foundation systems. To verify the performance of HSABCA, it is compared with the basic ABCA and a real coded genetic algorithm (RCGA) on two examples: a gravity dam and an arc dam. Results show that the proposed algorithm is an efficient tool for inverse analysis and it performs much better than ABCA and RCGA on such problems.
Kirigami, with facile and automated fashion of three-dimensional (3D) transformations, offers an unconventional approach for realizing cutting-edge optical nano-electromechanical systems. Here, we ...demonstrate an on-chip and electromechanically reconfigurable nano-kirigami with optical functionalities. The nano-electromechanical system is built on an Au/SiO
/Si substrate and operated via attractive electrostatic forces between the top gold nanostructure and bottom silicon substrate. Large-range nano-kirigami like 3D deformations are clearly observed and reversibly engineered, with scalable pitch size down to 0.975 μm. Broadband nonresonant and narrowband resonant optical reconfigurations are achieved at visible and near-infrared wavelengths, respectively, with a high modulation contrast up to 494%. On-chip modulation of optical helicity is further demonstrated in submicron nano-kirigami at near-infrared wavelengths. Such small-size and high-contrast reconfigurable optical nano-kirigami provides advanced methodologies and platforms for versatile on-chip manipulation of light at nanoscale.
Post-synthetic dealumination treatment is a common tactic adopted to improve the catalytic performance of industrialized zeolitic catalysts through enhancements in acidity and stability. However, ...among the possible extra-framework aluminum (EFAL) species in dealuminated zeolites such as Al3+, Al(OH)2+, Al(OH)2 +, AlO+, AlOOH, and Al(OH)3, the presence of tri-coordinated EFAL-Al3+ species, which exhibit large quadrupolar effect due to the lack of hydrogen-bonding species, was normally undetectable by conventional one- and two-dimensional 1H and/or 27Al solid-state nuclear magnetic resonance (SSNMR) techniques. By combining density functional theory (DFT) calculations with experimental 31P SSNMR using trimethylphosphine (TMP) as the probe molecule, we report herein a comprehensive study to certify the origin, fine structure, and possible location of tri-coordinated EFAL-Al3+ species in dealuminated HY zeolite. The spatial proximities and synergies between the Brønsted and various Lewis acid sites were clearly identified, and the origin for the observed EFAL-Al3+ species with ultra-strong Lewis acidity was deduced to be at the expense of adjacent Brønsted acid sites. The excellent performance of such tri-coordinated EFAL species was furthermore confirmed by glucose isomerization reactions.
Altered lipid metabolism is increasingly recognized as a signature of cancer cells. Enabled by label-free Raman spectromicroscopy, we performed quantitative analysis of lipogenesis at single-cell ...level in human patient cancerous tissues. Our imaging data revealed an unexpected, aberrant accumulation of esterified cholesterol in lipid droplets of high-grade prostate cancer and metastases. Biochemical study showed that such cholesteryl ester accumulation was a consequence of loss of tumor suppressor PTEN and subsequent activation of PI3K/AKT pathway in prostate cancer cells. Furthermore, we found that such accumulation arose from significantly enhanced uptake of exogenous lipoproteins and required cholesterol esterification. Depletion of cholesteryl ester storage significantly reduced cancer proliferation, impaired cancer invasion capability, and suppressed tumor growth in mouse xenograft models with negligible toxicity. These findings open opportunities for diagnosing and treating prostate cancer by targeting the altered cholesterol metabolism.
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•Aberrant cholesteryl ester accumulation is found in advanced human prostate cancer•Cholesteryl ester accumulation is induced by PTEN loss and PI3K/AKT activation•Inhibition of cholesterol esterification impairs cancer aggressiveness
Altered lipid metabolism is a signature of cancer cells. Yue et al. apply label-free Raman spectromicroscopy to reveal an aberrant accumulation of esterified cholesterol, induced by PTEN loss and PI3K/AKT activation, in advanced human prostate cancer. Inhibition of cholesterol esterification impairs cancer aggressiveness.
Intraperitoneal adhesions are common and serious complications after surgery. Deposition of proteins and inflammatory response on an injured cecum are the main factors resulting in the formation of ...adhesion. In this study, purely zwitterionic hydrogels (Z-hydrogels) are developed using thiolated poly(sulfobetaine methacrylate-co-2-((2-hydroxyethyl)disulfanyl)ethyl methacrylate) poly(SBMA-co-HDSMA) as the network backbone and divinyl-functionalized sulfobetaine (BMSAB) as the zwitterionic cross-linker via the thiol–ene click reaction. To improve the anti-inflammatory activity, cefoxitin sodium is loaded into Z-hydrogels (Z/C-hydrogel) to construct the physical barrier/drug system. The gelation time, mechanical behavior, and swelling ratio of the prepared Z-hydrogel can be modulated via adjusting the SBMA/HDSMA ratio in the copolymer. Moreover, they not only exhibit excellent resistance to protein and fibroblast adhesion but also show good biocompatibility and hemocompatibility. To assess its anti-adhesion effects in vivo, the Z-hydrogel is injected on the injured cecum surface using a rat model of sidewall defect-cecum abrasion. The results show that the Z-hydrogel can completely cover the irregular cecum surface and effectively suppress the formation of postoperative adhesion via reducing protein deposition and resisting fibroblast adhesion. Moreover, the introduction of cefoxitin sodium decreases the inflammatory response after surgery, thus further improving the anti-adhesion effect. Overall, we suggest that the Z-hydrogel is a promising candidate for the prevention of a postsurgical peritoneal adhesion.
Computational Fluid Dynamic (CFD) has been widely used for the gas release and dispersion modeling, which however could not support real-time emergency response planning due to its high computation ...overhead. Surrogate models offer a potential alternative to rigorous computational approaches, however, as the point-estimation alternatives, the existing neural network-based surrogate models are not able to quantify the uncertainty of the released gas spatial concentration. This study aims to fill a gap by proposing an advanced hybrid probabilistic Convolutional-Variational Autoencoder-Variational Bayesian neural network (Conv-VAE-VBnn). Experimental study based on a benchmark simulation dataset was conducted. The results demonstrated the additional uncertainty information estimated by the proposed model contributes to reducing the harmful effect of too ‘confidence’ of the point-estimation models. In addition, the proposed model exhibits competitive accuracy with R2 = 0.94 compared and real-time capacity with inference time less than 1s. Latent size Nz = 2, noise σz=0.1 and Monte Carlo sampling number m = 500 to ensure the model’s real-time capacity, were also given. Overall, our proposed model could provide a reliable alternative for constructing a digital twin for emergency management during the exploration and exploitation of marine natural gas hydrate (NHG) in the near future.
•Advanced probabilistic hybrid Conv-VAE-VBnn model is proposed.•Model correlates points with distribution of high dimensional spatial features.•Model quantifies uncertainty of spatial concentration given scenario-related inputs.•Model exhibits competitive accuracy and superior real-time application capability.•Hyper-parameters influencing model real-time application capability are analyzed.
A series of hydrochloric acid-doped polyaniline (PANI) were prepared by chemical oxidative polymerization. And the effects of HCl-doping concentration on the thermoelectric properties in the ...temperature range of 303–423
K were discussed. The results show that an increase in HCl-doping concentration will lead to a trend of first increase and then decrease in both the electrical conductivity and thermoelectric figure-of-merit ZT, accompanied by the opposite trend of the Seebeck coefficient. The maximum ZT can reach 2.67
×
10
−4 at 423
K when HCl-doping concentration is 1.0
M. Moreover, the temperature dependence of the electrical conductivity shows a transition from non-metallic to metallic sign with doping level increasing, while the Seebeck coefficient of all the samples has a metallic character.
•First, the G/AgNFs/PMMA flexible substrate was fabricated by using a facilegraphene templated electroreduction method.•Second, the detection limit for R6G in-situ detectionby covering the ...G/AgNFs/PMMA flexible substrate can reach 10−14M.•Third, the G/AgNFs/PMMA flexible substrate can be used on real-world objects with any arbitrary morphology.
Flexible substrate consisted of PMMA-supported monolayer graphene with sandwiched Ag-nanoflowers (G/AgNFs/PMMA) for ultrasensitive, reproducible, and stable surface-enhanced Raman scattering (SERS) detection is reported. Graphene templated micro-current-assisted chemical reduction method was employed to support AgNFs growth, and uniform-distribution AgNFs with all directions nanotips can generate tremendous enhancement factor and intensive hotspots. The minimum detectable concentration (i.e., detection limit) for rhodamine 6G (R6G) in-situ detection by covering this as-synthesized G/AgNFs/PMMA flexible substrate can be as low as 10−14M. Moreover, graphene can effectively stabilize the SERS signals and protect AgNFs from oxidation, endowing this flexible substrate a long-term stability with maximum intensity deviation lower than 10%, for the quantitative measurements from spot-to-spot or substrate-to-substrate. In order to trial its practical applications with various real-world surfaces, the in-situ SERS detection of phenylalanine@apple, adenosine aqueous solution and methylene-blue@fish was performed by covering this G/AgNFs/PMMA flexible substrate. Clear Raman peaks can be obtained for all the selected samples with concentration of 10−10M and, importantly, good linear relationship between Raman intensity and molecular concentration indicates the potential application of the G/AgNFs/PMMA flexible substrate in quantitative determination. Thus, this high-efficiency and low-cost flexible SERS substrate may provide a new way for the molecular trace-detection in food security and environmental protection.
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