Increased de novo lipogenesis is being increasingly recognized as a hallmark of cancer. Despite recent advances in fluorescence microscopy, autoradiography and mass spectrometry, direct observation ...of de novo lipogenesis in living systems remains to be challenging. Here, by coupling stimulated Raman scattering (SRS) microscopy with isotope labeled glucose, we were able to trace the dynamic metabolism of glucose in single living cells with high spatial-temporal resolution. As the first direct visualization, we observed that glucose was largely utilized for lipid synthesis in pancreatic cancer cells, which occurs at a much lower rate in immortalized normal pancreatic epithelial cells. By inhibition of glycolysis and fatty acid synthase (FAS), the key enzyme for fatty acid synthesis, we confirmed the deuterium labeled lipids in cancer cells were from de novo lipid synthesis. Interestingly, we also found that prostate cancer cells exhibit relatively lower level of de novo lipogenesis, but higher fatty acid uptake compared to pancreatic cancer cells. Together, our results demonstrate a valuable tool to study dynamic lipid metabolism in cancer and other disorders.
Single atom catalysts exhibit particularly high catalytic activities in contrast to regular nanomaterial-based catalysts. Until recently, research has been mostly focused on single atom catalysts, ...and it remains a great challenge to synthesize bimetallic dimer structures. Herein, we successfully prepare high-quality one-to-one A-B bimetallic dimer structures (Pt-Ru dimers) through an atomic layer deposition (ALD) process. The Pt-Ru dimers show much higher hydrogen evolution activity (more than 50 times) and excellent stability compared to commercial Pt/C catalysts. X-ray absorption spectroscopy indicates that the Pt-Ru dimers structure model contains one Pt-Ru bonding configuration. First principle calculations reveal that the Pt-Ru dimer generates a synergy effect by modulating the electronic structure, which results in the enhanced hydrogen evolution activity. This work paves the way for the rational design of bimetallic dimers with good activity and stability, which have a great potential to be applied in various catalytic reactions.
In recent years, all-inorganic lead halide perovskite CsPbX3 (X = Cl, Br, I) nanocrystals as kinds of new luminescent materials have attracted more and more attentions because of their size tunable ...emission wavelength, narrow emission peak, high luminous efficiency and good air stability. Herein we have synthesized all-inorganic halide perovskite nanocrystals by hot-injection method and anion exchange reaction, achieving the whole visible light region from 410 to 700 nm with narrow spectral in the range of 15–40 nm. Moreover, a white light emitting diode (WLED) was constructed by stacking CsPbBr3 QDs-ethyl acetate composite film and CaSrAlN3:Eu2+-poly (methyl methacrylate) composite film on the blue LED chip, displaying the ideal white light with the chromaticity coordination at (0.3379, 0.3432) and the color temperature of 5261 K. Because of the deep traps resulted from partial oxidation at the QDs' surface under large excitation light intensity, the WLED is not stable enough to work at a high operation current, but it can work steadily under a relatively lower operation current.
•All-inorganic perovskite CsPbX3 (X = Cl, Br, I) QDs with high PLQY were synthesized.•EC was demonstrated to protect perovskite QDs more effectively than PMMA.•The luminous decay mechanism attributed to the deep traps resulted from partial oxidation was proposed.•The ideal white light with the chromaticity coordination at (0.3379, 0.3432) and the color temperature of 5261 K was obtained.
•A machine learning model for eutectic high entropy alloys in Al–Co–Cr–Fe–Ni system are established.•The eutectics formation in the high entropy system is uncovered via data mining with machine ...learning.•A novel eutectic high entropy alloy design method with three steps is proposed.
Eutectics in high entropy alloys (HEAs) have shown excellent properties and promising applications. With empirical rules, various of eutectic high entropy alloys (EHEAs) have been proposed. The current design strategies shed light on the formation of eutectics in HEAs, but they are incapable of confirming multiple variables quantitatively in the selection of a specific system. In the present study, the eutectic formation in the multi-principal element systems is uncovered via data mining with machine learning (ML), where the critical elements and strongly associated elements were discovered. Taking the Al–Co–Cr–Fe–Ni system as an example, Al is confirmed to be the critical element for the eutectic formation and Cr is the strongly associated element with Al, Ni, Co, Fe and minor additions with comparably large solid solubility can be considered overall. With these understandings, a three-step approach can be summarized for designing EHEAs in a given system. Within the designed EHEAs, properties can be tested for optimization of application orientated design. The findings can not only accelerate the exploitation of EHEAs with better performance but also provide new ideas for designing compositionally complex alloys.
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Transition metal phosphides (TMPs) have recently emerged as a new class of pre-catalysts that can efficiently catalyze the oxygen evolution reaction (OER). However, how the OER activity of TMPs ...varies with the catalyst composition has not been systematically explored. Here, we report the alkaline OER electrolysis of a series of nanoparticulate phosphides containing different equimolar metal (M = Fe, Co, Ni) components. Notable trends in OER activity are observed, following the order of FeP < NiP < CoP < FeNiP < FeCoP < CoNiP < FeCoNiP, which indicate that the introduction of a secondary metal(s) to a mono-metallic TMP substantially boosts the OER performance. We ascribe the promotional effect to the enhanced oxidizing power of bi- and tri-metallic TMPs that can facilitate the formation of MOH and chemical adsorption of OH
groups, which are the rate-limiting steps for these catalysts according to our Tafel analysis. Remarkably, the tri-metallic FeCoNiP pre-catalyst exhibits exceptionally high apparent and intrinsic OER activities, requiring only 200 mV to deliver 10 mA cm
and showing a high turnover frequency (TOF) of ≥0.94 s
at the overpotential of 350 mV.
Supported metal clusters containing only a few atoms are of great interest. Progress has been made in synthesis of metal single-atom catalysts. However, precise synthesis of metal dimers on ...high-surface area support remains a grand challenge. Here, we show that Pt
dimers can be fabricated with a bottom-up approach on graphene using atomic layer deposition, through proper nucleation sites creation, Pt
single-atom deposition and attaching a secondary Pt atom selectively on the preliminary one. Scanning transmission electron microscopy, x-ray absorption spectroscopy, and theoretical calculations suggest that the Pt
dimers are likely in the oxidized form of Pt
O
. In hydrolytic dehydrogenation of ammonia borane, Pt
dimers exhibit a high specific rate of 2800 mol
mol
min
at room temperature, ~17- and 45-fold higher than graphene supported Pt single atoms and nanoparticles, respectively. These findings open an avenue to bottom-up fabrication of supported atomically precise ultrafine metal clusters for practical applications.
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•A novel self-reducible Cu nanoparticle paste was proposed.•A high Cu-Cu bonding strength of over 50 MPa can be achieved at 250 °C under air condition.•The sintering mechanism was ...studied.
The development of WBG (wide bandgap) semiconductors has put forward higher requirements for packaging and interconnection technology. Cu sintering is widely considered as an advanced interconnection technology which can be used in high temperature and high power density service. In this paper, a new type of self-reducible Cu nanoparticle paste was proposed to solve the problems of easy oxidation and high sintering temperature of normal Cu nanoparticles. The proposed Cu paste was developed by mixing formic acid treated Cu nanoparticles, reducing solvents and MOD (metal organic decomposition) solutions. Based on the new type of self-reducible Cu nanoparticle paste, Cu-Cu bonding experiments were carried out with different bonding temperature and time, and a reliable Cu-Cu joint with a high shear strength of 52.01 MPa can be achieved at 250 °C under ambient condition, without any assistance of reducing or inert atmosphere. In addition, the MOD assisted self-reduction and sintering mechanism was proposed after shear strength testing, element composition analyzing, cross-sectional morphology and fracture structure observation, which can provide an effective theoretical support for the practical application of Cu-Cu bonding.
Lack of sensitive single-cell analysis tools has limited the characterization of metabolic activity in cancer stem cells. By hyperspectral-stimulated Raman scattering imaging of single living cells ...and mass spectrometry analysis of extracted lipids, we report here significantly increased levels of unsaturated lipids in ovarian cancer stem cells (CSCs) as compared to non-CSCs. Higher lipid unsaturation levels were also detected in CSC-enriched spheroids compared to monolayer cultures of ovarian cancer cell lines or primary cells. Inhibition of lipid desaturases effectively eliminated CSCs, suppressed sphere formation in vitro, and blocked tumor initiation capacity in vivo. Mechanistically, we demonstrate that nuclear factor κB (NF-κB) directly regulates the expression levels of lipid desaturases, and inhibition of desaturases blocks NF-κB signaling. Collectively, our findings reveal that increased lipid unsaturation is a metabolic marker for ovarian CSCs and a target for CSC-specific therapy.
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•Ovarian cancer stem cells have high levels of unsaturated lipids•Blocking lipid desaturation impairs cancer stemness and tumor initiation capacity•The NF-κB pathway directly regulates the expression of lipid desaturases•Lipid desaturase inhibitors inactivate the NF-κB pathway
Cheng and colleagues using Raman spectroscopic imaging find that ovarian cancer stem cells contain unusually high levels of unsaturated lipids and show evidence that this metabolic difference could be used as a marker for these cells and as a new target for CSC-specific therapy.
CoCrFeNi alloy is an exemplary stable base for high entropy alloys (HEAs), but its phase stability is still suspicious. Here, the CoCrFeNi HEA was firstly identified to be thermally metastable at ...750°C. Composition decomposition occurred after annealed at 750°C for 800h. The minor addition of Al accelerated the composition decomposition and a second fcc phase with a different lattice constant occurred in the long time annealed CoCrFeNiAl0.1 HEA. The CoCrFeNi HEA cannot be seen as stable alloys anymore and researchers should be very careful when using the current phase selection models to predict stability of HEAs at intermediate temperatures.
Composition decompositon occurred in the CoCrFeNi high entropy alloy after annealed at 750°C for 800h (see (a, b)). The addition of Al accelerated the decomposition and a second fcc phase with different lattice precipitated from the CoCrFeNi base, as shown in (c and d). These results indicated that the CoCrFeNi high entropy alloy is a metastable solid solution. Display omitted
Abstract
Zwitterionic hydrogels exhibit eminent nonfouling and hemocompatibility. Several key challenges hinder their application as coating materials for blood-contacting biomedical devices, ...including weak mechanical strength and low adhesion to the substrate. Here, we report a poly(carboxybetaine) microgel reinforced poly(sulfobetaine) (pCBM/pSB) pure zwitterionic hydrogel with excellent mechanical robustness and anti-swelling properties. The pCBM/pSB hydrogel coating was bonded to the PVC substrate via the entanglement network between the pSB and PVC chain. Moreover, the pCBM/pSB hydrogel coating can maintain favorable stability even after 21 d PBS shearing, 0.5 h strong water flushing, 1000 underwater bends, and 100 sandpaper abrasions. Notably, the pCBM/pSB hydrogel coated PVC tubing can not only mitigate the foreign body response but also prevent thrombus formation ex vivo in rats and rabbits blood circulation without anticoagulants. This work provides new insights to guide the design of pure zwitterionic hydrogel coatings for biomedical devices.
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