Two‐dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are ...mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal–organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared‐layer framework. When the 3D pillared‐layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal–organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm−2 and a turnover frequency as high as 30 s−1 at an overpotential of 300 mV.
MOF slicing: A pillared‐layer metal–organic framework (MOF), in which the catechol functionalized pillars can be oxidized and removed in an electrochemical process, gives ultrathin nanosheets (2 nm). These are efficient electrocatalysts for water oxidation at pH 13 with a low overpotential and high turnover frequency (TOF).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Efficient adsorptive separation of propylene/propane (C3H6/C3H8) is highly desired and challenging. Known strategies focus on either the thermodynamic or the kinetic mechanism. Here, we report an ...interesting reactivity of a metal–organic framework that improves thermodynamic and kinetic adsorption selectivity simultaneously. When the metal–organic framework is heated under oxygen flow, half of the soft methylene bridges of the organic ligands are selectively oxidized to form the more polar and rigid carbonyl bridges. Mixture breakthrough experiments showed drastic increase of C3H6/C3H8 selectivity from 1.5 to 15. For comparison, the C3H6/C3H8 selectivities of the best‐performing metal–organic frameworks Co‐MOF‐74 and KAUST‐7 were experimentally determined to be 6.5 and 12, respectively. Gas adsorption isotherms/kinetics, single‐crystal X‐ray diffraction, and computational simulations revealed that the oxidation gives additional guest recognition sites, which improve thermodynamic selectivity, and reduces the framework flexibility, which generate kinetic selectivity.
Tailoring with O2: When a flexible metal–organic framework is heated in a flow of oxygen, half of the organic ligands are selectively oxidized, thereby adding guest recognition sites and reducing the flexibility of the pores. As a result, the thermodynamic and kinetic selectivity for propylene/propane separation improve simultaneously.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A facile yet effective surface modification strategy for superhydrophilicity and underwater superoleophobicity was developed by silanization of zwitterionic sulfobetaine silane (SBSi) on oxidized ...surfaces. The coatings exhibit excellent wetting properties, as indicated by static contact angles of <5°, and long-term stability under exposure to heat and UV irradiation. The SBSi-modified surfaces were employed for applications in antifog, self-cleaning, and oil–water separation. The SBSi glasses retained their optical transmittance because of the rapid formation of coalesced water thin films on surfaces in contact with water vapor and moisture. In addition, the underwater–oil contact-angle measurements verified the underwater superoleophobicity of the zwitterionic SBSi coatings. The oil spills on the SBSi coating could be readily removed in contact with water to realize the self-cleaning property. Besides, we modified stainless steel wire meshes with SBSi for oil–water separation. The optimal oil recovery rate for the oil–water mixtures reached >99.5% when using the SBSi-coated meshes with a pore size of 17 μm. More importantly, the water flux with modified meshes achieved 6.5 × 107 L/m2·h·bar, enabling gravity-driven and energy-saving separation. Consequently, we demonstrated the superhydrophilicity and underwater superoleophobicity of SBSi, offering promise in solving technological problems of interfacial fog, oil spills, and oil–water separation and thereby showing great potential in large-scale commercial applications.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
Purpose
To investigate the relationship between the preoperative paraspinal Goutalier grade of fatty infiltration and postoperative cervical sagittal alignment in patients undergoing ...anterior cervical discectomy and fusion (ACDF).
Methods
A total of 101 patients who underwent single-level ACDF with the Zero-profile implant system between March 2011 and April 2020 were included in this study. Cervical sagittal alignment parameters, including the C2-C7 Cobb angle, functional spinal unit (FSU) angle, cervical sagittal vertical axis (SVA), and T1 slope (T1S), were assessed. Preoperative magnetic resonance images were used to classify patients according to Goutalier grade. Clinical outcomes including Neck Disability Index (NDI) scores, Japanese Orthepaedic Association (JOA) scores and Visual Analogue Scale (VAS) scores were collected and analyzed.
Results
According to the Goutalier grade, 33 patients were classified as Goutalier 0–1 (Group A), 44 were classified as Goutalier 1.5–2 (Group B), and 24 were classified as Goutalier 2.5–4.0 (Group C). The mean age among the three groups showed significant differences (
P
= 0.007). At the last follow-up, the C2-C7 Cobb angle, FSU angle, and T1S improved after the surgery among the groups. Although there were varying degrees of loss of curvature among the different groups during the follow-up period, the postoperative cervical sagittal alignment parameters demonstrated no statistical differences among the three groups (
P
> 0.05). In addition, patients in all groups experienced significant relief of their symptoms, and the clinical scores were comparable among the groups (
P
> 0.05).
Conclusion
The complex nature of anterior cervical surgery requires surgical attention both in decompression and sagittal alignment. Our study demonstrates satisfactory postoperative cervical sagittal alignment of patients despite different grades of fatty infiltration of the multifidus muscle following single-level ACDF. Based on our results, the improvement and maintenance of cervical sagittal alignment after ACDF remains a complex problem that spine surgeons should consider before surgery.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Metasurface assisted terahertz (THz) real-time and label-free biosensors have attracted intense attention. However, it is still challenging for specific detection of highly absorptive liquid samples ...with high sensitivity in the THz range. Here, we incorporated graphene with THz metasurface into a microfluidic cell for sensitive biosensing. The proposed THz graphene-metasurface microfluidic platform can effectively reduce the volume of the sample solution and boost the interaction between biomolecules and THz waves, thus enhancing the sensitivity. As a proof of concept, comparative experiments using other three kinds of microfluidic cells (pure microfluidic cell, metasurface-based microfluidic cell and graphene-based microfluidic cell) were conducted to explore and verify the sensing mechanism, which evidences the high sensitivity of delicate sensing based on the hybrid graphene-metasurface THz microfluidic device. Furthermore, to perform biosensing applications on that basis, specific aptamers were modified on the graphene-metasurface, enabling DNA sequences of foodborne pathogen Escherichia coli O157:H7 to be recognized. Based on the THz microfluidic biosensor, 100 nM DNA short sequences can be successfully detected. The sensing results of antibiotics and DNA based on the graphene-metasurface microfluidic biosensor confirm the superiority of the proposed design and considerable promise in THz biosensing. The novel sensing platform provides the merits of enabling highly sensitive, label-free, low-cost, easy to use, reusable, and real-time biosensing, which opens an exciting prospect for nanomaterial-metasurface hybrid structure assisted THz label-free biosensing in liquid environment.
•A novel microfluidic platform integrating graphene with metasurface is reported.•Sensitive terahertz molecular detection in liquid environment is realized.•DNA sequences of foodborne pathogen can be recognized with high selectivity.•The biosensing capability can be restored through a simple regeneration process.•The hybrid metasurface-graphene structure can improve the sensitivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This work presents a salt-responsive interpenetrating network (IPN) hydrogel with effective antimicrobial properties and surface regeneration. The hydrogels were engineered using the double network ...strategy to form loosely cross-linked zwitterionic poly(sulfobetaine vinylimidazole) (pSBVI) networks into the highly cross-linked cationic poly((trimethylamino)ethyl methacrylate chloride) (pTMAEMA) framework via photopolymerization. The pTMAEMA/pSBVI hydrogel has strong mechanical properties, with a fracture stress 120× higher than single network pTMAEMA hydrogel. In addition, there is inverse correlation between elastic modulus and elastic strain of pTMAEMA/pSBVI hydrogels as a function of ionic strength. The cationic pTMAEMA and zwitterionic pSBVI show opposite swelling behaviors in salt solutions due to the polyelectrolyte effect and antipolyelectrolyte effect. Therefore, the pTMAEMA/pSBVI hydrogel elicits a significant interfacial transition in solutions with different ionic strengths. The IPN hydrogels have switchable lubrication and optical transmittance between deionized water and 1.0 M NaCl solution. The protein adsorption tests further confirmed the switchable interface of salt-responsive IPN hydrogels. In addition, bacterial attachment test on pTMAEMA/pSBVI hydrogels with Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli) show bacterial killing rates of the IPN hydrogel over 80% for S. epidermidis and 90% for E. coli after incubating the hydrogels in the bacterial solutions for 24 h. The bacterial release rate from the IPN hydrogel reached 96% after washing with 1.0 M NaCl solution. Furthermore, the excellent reusability of the pTMAEMA/pSBVI hydrogels was demonstrated by the high bacterial killing and bacterial release rates after five kill/release cycles. The work presents a new stimuli-responsive IPN hydrogel with structural modulation, tunable antimicrobial properties, and surface regeneration by ionic strength. Integrating two salt-responsive polymers with mutually independent actions into a single material provides a new direction for smart materials with potential medical and industrial applications.
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IJS, KILJ, NUK, PNG, UL, UM
Earth's biosphere witnessed the first major extinction event in the Phanerozoic during the Cambrian Age 4, with a genera loss up to ∼45%. The traditional view suggested that marine anoxia was the ...main cause of the biotic crisis, yet recent geochemical investigations yielded highly debated opinions on marine redox states during the Cambrian Age 4. Herein, we supplement new geochemical evidence for expanded marine euxinia at the extinction intervals on the Yangtze Platform, South China. Most importantly, modern‐level sedimentary δ98Mo (∼+2.34‰) records were most parsimoniously explained by transitory expansion of continental margin euxinia and concomitant intensification of sedimentary Mo sequestration via Fe‒Mn shuttles in the global ocean. The results clarify global marine redox conditions during the Cambrian Age 4, and lend firm support to a causal link between expanded marine euxinia and the extinction event.
Plain Language Summary
Marine life experienced the first major mass extinction during the Cambrian Age 4 (∼509–514 Ma) right after the Cambrian explosion, with a genera loss up to ∼45%. The mass extinction was traditionally attributed to expanded marine anoxia in the global ocean based on lithological changes, but geochemical evidence for this scenario is still lacking. Molybdenum (Mo) isotopes can be used to track global marine redox states in ancient oceans. Herein, new Mo isotope data revealed transitory expansion of sulfidic waterbodies on in the global ocean at the major mass extinction intervals. Sulfidic waters enriched in H2S are lethal for marine animals. Therefore, expanded sulfidic waterbodies in the global ocean could have served as a major driver for the mass extinction event.
Key Points
Dynamic marine Mo cycling via Fe‒Mn shuttles during the Cambrian Age 4 is revealed
Robust Mo isotope evidence for expanded continental margin euxinia in the global ocean during mass extinction
Firm support to a causal link between expanded marine euxinia and the extinction event
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A rigid hydrogen‐bonded organic framework (HOF) was constructed from a C3‐symmetric hexatopic carboxylic acid with a hydrophilic 18‐crown‐6‐ether (18C6) component. Despite the flexible macrocyclic ...structure with many conformations, the derivative with three 4,4’‐dicarboxy‐o‐terphenyl moieties in the periphery yielded a rigid layered porous framework through directional intermolecular hydrogen bonding. Interestingly, the HOF possesses 1D channels with bottleneck composed of 18C6 rings. The HOF shows proton conductivity (1.12×10−7 S cm−1) through Grotthuss mechanism (Ea=0.27 eV) under 98 %RH. The present unique water channel structure provides an inspiration to create molecular porous materials.
A porous hydrogen‐bonded framework (HOF) was constructed from a 18‐crown‐6‐ether (18C6) derivative. Although a 18C6 macrocycle is flexible and has many possible conformations, directional intermolecular hydrogen bonds of 4,4′‐dicarboxy‐o‐terphenyl modules in the periphery of the 18C6 allowed to form a rigid HOF with 1D channels with a bottleneck composed of 18C6 rings. The wet HOF shows proton conductivity (1.12×10−7 S cm−1) through a Grotthuss mechanism (Ea=0.27 eV) under 98 %RH.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Amid growing interest in using body heat for electricity in wearables, creating stretchable devices poses a major challenge. Herein, a hydrogel composed of two core constituents, namely the ...negatively‐charged 2‐acrylamido‐2‐methylpropanesulfonic acid and the zwitterionic (ZI) sulfobetaine acrylamide, is engineered into a double‐network hydrogel. This results in a significant enhancement in mechanical properties, with tensile stress and strain of up to 470.3 kPa and 106.6%, respectively. Moreover, the ZI nature of the polymer enables the fabrication of a device with polar thermoelectric properties by modulating the pH. Thus, the ionic Seebeck coefficient (Si) of the ZI hydrogel ranges from −32.6 to 31.7 mV K−1 as the pH is varied from 1 to 14, giving substantial figure of merit (ZTi) values of 3.8 and 3.6, respectively. Moreover, a prototype stretchable ionic thermoelectric supercapacitor incorporating the ZI hydrogel exhibits notable power densities of 1.8 and 0.9 mW m−2 at pH 1 and 14, respectively. Thus, the present work paves the way for the utilization of pH‐sensitive, stretchable ZI hydrogels for thermoelectric applications, with a specific focus on harvesting low‐grade waste heat within the temperature range of 25–40 °C.
Combining p‐type and n‐type devices is an approach to enhance ionic thermoelectric properties. Herein, a pH‐sensitive zwitterionic hydrogel achieves bipolar thermoelectric performance, with a Seebeck coefficient of −32.6 to 31.7 mV K−1 at pH 1 and 14. Research into controlled pH values opens avenues for advancing the bipolar Seebeck coefficient in ionic thermoelectric supercapacitors, highlighting promising possibilities in the field.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
