Open coordination sites (OCSs) in metal–organic frameworks (MOFs) often function as key factors in the potential applications of MOFs, such as gas separation, gas sorption, and catalysis. For these ...applications, the activation process to remove the solvent molecules coordinated at the OCSs is an essential step that must be performed prior to use of the MOFs. To date, the thermal method performed by applying heat and vacuum has been the only method for such activation. In this report, we demonstrate that methylene chloride (MC) itself can perform the activation role: this process can serve as an alternative “chemical route” for the activation that does not require applying heat. To the best of our knowledge, no previous study has demonstrated this function of MC, although MC has been popularly used in the pretreatment step prior to the thermal activation process. On the basis of a Raman study, we propose a plausible mechanism for the chemical activation, in which the function of MC is possibly due to its coordination with the Cu2+ center and subsequent spontaneous decoordination. Using HKUST-1 film, we further demonstrate that this chemical activation route is highly suitable for activating large-area MOF films.
Although metastable crystal structures have received much attention owing to their utilization in various fields, their phase‐transition to a thermodynamic structure has attracted comparably little ...interest. In the case of nanoscale crystals, such an exothermic phase‐transition releases high energy within a confined surface area and reconstructs surface atomic arrangement in a short time. Thus, this high‐energy nanosurface may create novel crystal structures when some elements are supplied. In this work, the creation of a ruthenium carbide (RuCX, X < 1) phase on the surface of the Ru nanocrystal is discovered during phase‐transition from cubic‐close‐packed to hexagonal‐close‐packed structure. When the electrocatalytic hydrogen evolution reaction (HER) is tested in alkaline media, the RuCX exhibits a much lower overpotential and good stability relative to the counterpart Ru‐based catalysts and the state‐of‐the‐art Pt/C catalyst. Density functional theory calculations predict that the local heterogeneity of the outermost RuCX surface promotes the bifunctional HER mechanism by providing catalytic sites for both H adsorption and facile water dissociation.
Crystal phase‐transition of Ru/C from cubic‐close‐packing to hexagonal‐close‐packing creates a ruthenium carbide (RuCX, X < 1) nanosurface on Ru nanocrystal. The as‐created RuCX nanosurface presents a highly active and stable performance for the hydrogen evolution reaction (HER) in alkaline media. Density functional theory calculations predict the RuCX sites as bifunctional configurations for improving alkaline HER kinetics.
It is well known that, surfactants provide a neutral, positive and/or negative charge on the electrode surface by forming a monolayer, which in turn affects the charge transfer and redox potential ...during the electroanalysis process. However, the molecular level understanding of these surfactant-modified electrodes is worth investigating because the interaction of the analyte with the electrode surface is still unclear. In this report, we used quantum chemical models based on computational density functional theory (DFT) to investigate the polysorbate 80 structure as well as the locations of energy levels and electron transfer sites. Later, the bare carbon paste electrode (bare/CPE) was modified with polysorbate 80 and used to resolve the overlapped oxidation signals of dihydroxy benzene isomers. The m/n values obtained at polysorbate/CPE was approximately equal to 1, signifying the transfer of same number of protons and electrons. Moreover, the analytical applicability of the modified electrode for the determination of catechol (CC) and hydroquinone (HQ) in tap water samples gave an acceptable recovery result. Overall, the application of DFT to understand the molecular level interaction of modifiers for sensing applications laid a new foundation for fabricating electrochemical sensors.
Background and Aims
How Wnt signaling is orchestrated in liver regeneration and tumorigenesis remains elusive. Recently, we identified transmembrane protein 9 (TMEM9) as a Wnt signaling amplifier.
...Approach and Results
TMEM9 facilitates v‐ATPase assembly for vesicular acidification and lysosomal protein degradation. TMEM9 is highly expressed in regenerating liver and hepatocellular carcinoma (HCC) cells. TMEM9 expression is enriched in the hepatocytes around the central vein and acutely induced by injury. In mice, Tmem9 knockout impairs hepatic regeneration with aberrantly increased adenomatosis polyposis coli (Apc) and reduced Wnt signaling. Mechanistically, TMEM9 down‐regulates APC through lysosomal protein degradation through v‐ATPase. In HCC, TMEM9 is overexpressed and necessary to maintain β‐catenin hyperactivation. TMEM9–up‐regulated APC binds to and inhibits nuclear translocation of β‐catenin, independent of HCC‐associated β‐catenin mutations. Pharmacological blockade of TMEM9‐v‐ATPase or lysosomal degradation suppresses Wnt/β‐catenin through APC stabilization and β‐catenin cytosolic retention.
Conclusions
Our results reveal that TMEM9 hyperactivates Wnt signaling for liver regeneration and tumorigenesis through lysosomal degradation of APC.
Ultrafast optical manipulation of magnetic phenomena is an exciting achievement of mankind, expanding one's horizon of knowledge toward the functional nonequilibrium states. The dynamics acting on an ...extremely short timescale push the detection limits that reveal fascinating light–matter interactions for nonthermal creation of effective magnetic fields. While some cases are benchmarked by emergent transient behaviors, otherwise identifying the nonthermal effects remains challenging. Here, a femtosecond time‐resolved resonant magnetic X‐ray diffraction experiment is introduced, which uses an X‐ray free‐electron laser (XFEL) to distinguish between the effective field and the photoinduced thermal effect. It is observed that a multiferroic Y‐type hexaferrite exhibits magnetic Bragg peak intensity oscillations manifesting entangled antiferromagnetic (AFM) and ferromagnetic (FM) Fourier components of a coherent AFM magnon. The magnon trajectory constructed in 3D space and time domains is decisive to evince ultrafast field formation preceding the lattice thermalization. A remarkable impact of photoexcitation across the electronic bandgap is directly unraveled, amplifying the photomagnetic coupling that is one of the highest among AFM dielectrics. Leveraging the above‐bandgap photoexcitation, this energy‐efficient optical process further suggests a novel photomagnetic control of ferroelectricity in multiferroics.
Femtosecond time‐resolved resonant magnetic X‐ray diffraction experiment using an X‐ray free electron laser visualizes a light‐induced coherent magnon in a multiferroic. The magnon trajectory in time and 3D space unveils the photomagnetic coupling largely enhanced by above‐bandgap photoexcitation, distinguished from a laser‐heated magnetic behavior. This energy‐efficient photoexcitation process suggests the potential for a novel photomagnetic control of ferroelectricity in multiferroics.
It has been a major challenge to develop stable and cost-effective porous materials that efficiently recover heavy rare earth elements (HREEs) due to ever-increasing demand, low availability and high ...cost of HREEs. This study presents two novel benzylphosphate-based covalent porous organic polymers (BPOP-1 and BPOP-2) that were prepared by facile one-pot Friedel-Crafts reactions. Various analytical techniques are used to investigate the successful syntheses of BPOP materials and establish their material properties, which include an unusual crystalline nature, large surface area, hierarchical pore structure, and superior chemical stabilities. The BPOPs effectively adsorb, and thus remove HREEs from aqueous media. In particular, BPOP-1 had higher phosphate content and exhibits superior adsorption capacities (Eu3+: 289.5; Gd3+: 292.7; Tb3+: 294.4; Dy3+: 301.9 mg/g) than BPOP-2, while BPOP-2 had higher mesoporosity and correspondingly supports faster adsorption kinetics. Remarkably, both BPOP materials exhibit some of the highest HREE adsorption capacities reported to date, the selective capture of Dy3+ ions, and excellent cyclic adsorption/desorption properties. We provide a potential adsorption mechanism for Dy3+ capture by the BPOP adsorbent. These demonstrate that introducing phosphate functionality into a robust porous polymer backbone with high surface area is a promising strategy for selective HREEs capture from wastewater.
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•Novel benzylphosphate-based porous organic polymers (BPOPs) were synthesized.•BPOPs showed excellent adsorption capacity for heavy rare earth elements.•BPOPs display selective Dy3+ capture over competitive divalent and monovalent ions.•BPOPs exhibit excellent chemical stability and reusability.•A plausible mechanism for trivalent metal binding on phosphate is proposed.
Soft Haptic Actuator Based on Knitted PVC Gel Fabric Park, Won-Hyeong; Shin, Eun-Jae; Yoo, Yongjae ...
IEEE transactions on industrial electronics (1982),
2020-Jan., 2020-1-00, 20200101, Letnik:
67, Številka:
1
Journal Article
Recenzirano
An electroactive and actuator made of knitted polyvinyl chloride (PVC) gel fabric is proposed herein. This haptic actuator consists of an upper layer, a lower layer, and fabric made by twisting long ...and slender PVC gel strings. The PVC gel fabric changes its shape according to the input voltage waveform, and exerts an electrostatic force between the upper and lower layers. When the applied voltage is removed, the PVC gel fabric rapidly restores to its initial configuration. Consequently, these effects generate vibrations that are sufficiently strong for human perception. In this paper, we conducted quantitative experiments to investigate the performance of our soft haptic actuator using an accelerometer and a laser scanning vibrometer. Furthermore, we performed a perceptual evaluation and the results indicate that our proposed actuator can stimulate the human skin with sufficient perceptual strength.
Two go in, one comes out: A series of isostructural M‐MOF‐74 materials (M=Co, Mn, and Mg) with high densities of open metal sites have been examined for the selective adsorption of propene over ...propane. Co‐MOF‐74 exhibits the highest thermodynamic C3H6/C3H8 selectivity (ca. 45) reported for any MOF to date.
The development of nonenzymatic glucose sensors with favorable electrocatalytic activity and chemical stability is crucial in various fields. Therefore, in this study, we systematically investigate a ...series of ZIF-Zn x Co1–x materials (0 ≤ x ≤ 1) and demonstrate that the appropriate combination of Zn2+ and Co2+ within a metal–organic framework (MOF) delivers a promising platform for developing a glucose sensor with good glucose sensitivity and superior chemical stability. Herein, ZIF-Zn0.5Co0.5 was selected as the optimal glucose-sensing material owing to its high Co2+ content and well-preserved crystallinity and porosity after base treatment for 14 days. Remarkably, ZIF-Zn0.5Co0.5 showed superior electrocatalytic glucose-sensing performance compared to ZIF-67(Co) owing to its excellent chemical stability. The observed glucose-sensing performance was comparable to those of benchmark cobalt-based electrocatalysts. Furthermore, ZIF-Zn0.5Co0.5 exhibited excellent selectivity for glucose over possible interfering species, as well as reusability and electrochemical stability, thereby suggesting its potential applicability for nonenzymatic glucose sensing.
Ultrafast lasers are an increasingly important tool to control and stabilize emergent phases in quantum materials. Among a variety of possible excitation protocols, a particularly intriguing route is ...the direct light engineering of microscopic electronic parameters, such as the electron hopping and the local Coulomb repulsion (HubbardU). In this work, we use time-resolved x-ray absorption spectroscopy to demonstrate the light-induced renormalization of the HubbardUin a cuprate superconductor,La1.905Ba0.095CuO4. We show that intense femtosecond laser pulses induce a substantial redshift of the upper Hubbard band while leaving the Zhang-Rice singlet energy unaffected. By comparing the experimental data to time-dependent spectra of single- and three-band Hubbard models, we assign this effect to an approximately 140-meV reduction of the on-site Coulomb repulsion on the copper sites. Our demonstration of a dynamical HubbardUrenormalization in a copper oxide paves the way to a novel strategy for the manipulation of superconductivity and magnetism as well as to the realization of other long-range-ordered phases in light-driven quantum materials.
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