Avoiding the Kinetic Inertness of Chromium Ions Using a Coordination Substitution Strategy for the Rapid Synthesis of Chromium-Based Metal-Organic Frameworks.

Chromium-based metal-organic frameworks (Cr-MOFs) are very attractive in a wide range of applications due to their robustness and high porosity. However, the kinetic inertness of chromium ions results in the synthesis of Cr-MOFs often taking prolonged reaction times, which limit their industrial applications. Herein, we report a novel synthesis strategy based on coordination substitution, which overcomes the kinetic inertness of chromium ions and can synthesize Cr-MOFs in a shorter time. The versatility of this strategy has been demonstrated by producing several known Cr-MOFs, such as TYUT-96Cr, MIL-100Cr, MIL-101Cr, and MIL-53Cr. PXRD, SEM, TEM, 77 K N2 adsorption, and TGA have proved that the Cr-MOFs synthesized using this new strategy have good crystallinity, high porosity, and excellent thermal stability. The synthesis mechanism was investigated using theoretical calculations.

Superconductivity in Freestanding Infinite-Layer Nickelate Membranes.

The observation of superconductivity in infinite-layer nickelates has attracted significant attention due to its potential as a new platform for exploring high-Tc superconductivity. However, thus far, superconductivity has only been observed in epitaxial thin films, which limits the manipulation capabilities and modulation methods compared to two-dimensional exfoliated materials. Given the exceptionally giant strain tunability and stacking capability of freestanding membranes, separating superconducting nickelates from the as-grown substrate is a novel way to engineer the superconductivity and uncover the underlying physics. Herein, this work reports the synthesis of the superconducting freestanding La0.8Sr0.2NiO2 membranes ( T c zero = 10.6 K ${T}_{\mathrm{c}}^{\mathrm{zero}}\ =\ 10.6\ \mathrm{K}$ ), emphasizing the crucial roles of the interface engineering in the precursor phase film growth and the quick transfer process in achieving superconductivity. This work offers a new versatile platform for investigating superconductivity in nickelates, such as the pairing symmetry via constructing Josephson tunneling junctions and higher Tc values via high-pressure experiments.

Effect of the Number of Methyl Groups in DMOF on N2O Adsorption and N2O/N2 Separation.

Nitrous oxide (N2O), as the third largest greenhouse gas in the world, also has great applications in industry, so the purification of N2O from N2 in industrial tail gas is a crucial process for achieving environmental protection and giving full play to its economic value. Based on the polarity difference of N2O and N2, N2O adsorption was researched on DMOF series materials with different polarities and methyl numbers of the ligand. N2O adsorption at 0.1 bar is enhanced, attributed to an increase of the methyl group densities at the benzenedicarboxylate linker. Grand canonical Monte Carlo simulations demonstrate the key role of methyl groups within the pore surface in the preferential N2O affinity. Methyl groups preferentially bind to N2O and thus enhanced low (partial) pressure N2O adsorption and N2O/N2 separation. The result shows that DMOF-TM has the highest N2O adsorption capacity (19.6 cm3/g) and N2O/N2 selectivity (23.2) at 0.1 bar. Breakthrough experiments show that, with an increase of the methyl number, the coadsorption time and retention time also increase, and DMOF-TM has the best N2O/N2 separation performance.

Inverse Adsorption Separation of N2 O/CO2 in AgZK-5 Zeolite.

Nitrous oxide (N2 O), as the third largest greenhouse gas in the world, also has great applications in daily life and industrial production, like anesthetic, foaming agent, combustion supporting agent, N or O atomic donor. The capture of N2 O in adipic acid tail gas is of great significance but remains challenging due to the similarity with CO2 in molecular size and physical properties. Herein, the influence of cation types on CO2 -N2 O separation in zeolite was studied comprehensively. In particular, the inverse adsorption of CO2 -N2 O was achieved by AgZK-5, which preferentially adsorbs N2 O over CO2 , making it capable of trapping N2 O from an N2 O/CO2 mixture. AgZK-5 shows a recorded N2 O/CO2 selectivity of 2.2, and the breakthrough experiment indicates excellent performance for N2 O/CO2 separation. The density functional theory (DFT) calculation shows that Ag+ has stronger adsorption energy with N2 O, and the kinetics of N2 O is slightly faster than that of CO2 on AgZK-5.

Synergistic Nitrogen Binding Sites in a Metal-Organic Framework for Efficient N2 /O2 Separation.

Porous materials with d3 electronic configuration open metal sites have been proved to be effective adsorbents for N2 capture and N2 /O2 separation. However, the reported materials remain challenging to address the trade-off between adsorption capacity and selectivity. Herein, we report a robust MOF, MIL-102Cr, that features two binding sites, can synergistically afford strong interactions for N2 capture. The synergistic adsorption site exhibits a benchmark Qst of 45.0 kJ mol-1 for N2 among the Cr-based MOFs, a record-high volumetric N2 uptake (31.38 cm3 cm-3 ), and highest N2 /O2 selectivity (13.11) at 298 K and 1.0 bar. Breakthrough experiments reveal that MIL-102Cr can efficiently capture N2 from a 79/21 N2 /O2 mixture, providing a record 99.99 % pure O2 productivity of 0.75 mmol g-1 . In situ infrared spectroscopy and computational modelling studies revealed that a synergistic adsorption effect by open Cr(III) and fluorine sites was accountable for the strong interactions between the MOF and N2 .

A Customized Hydrophobic Porous Shell for MOF-5.

The susceptibility to moisture of metal-organic frameworks (MOFs) is a critical bottleneck for their wider practical application. Constructing core-shell composites has been postulated as an effective strategy for enhancing moisture resistance, but for fragile MOFs this has rarely been accomplished. We report herein, for the first time, the construction of a customized hydrophobic porous shell, NTU-COF, on the particularly fragile MOF-5 by a "Plug-Socket Anchoring" strategy. Notably, the pore structure of MOF-5 was well maintained, and it could still achieve complete CO2/N2 separation under humid conditions. The homogeneous interface between MOF-5 and NTU-COF has been inspected at atomic resolution by a combination of cryogenic focused ion beam (cryo-FIB) and ultralow-dose (scanning) transmission electron microscope giving profound insight into the mechanism of assembly of the core-shell structure. This work presents a facile strategy for the fabrication of a hydrophobic porous shell for labile MOFs, and provides a general approach for solving the problem of moisture instability of porous materials for practical applications.

Growth of wafer-scale chromium sulphide and selenide semiconductor films.

Two-dimensional (2D) transition metal chalcogenides have attracted enormous attention due to their stunning properties and great prospects for applications. Most of the reported 2D materials have layered structure, and non-layered transition metal chalcogenides are rare. Particularly, chromium chalcogenides are highly complexed in terms of structural phases. Researches on their representative chalcogenides, Cr2S3and Cr2Se3, are insufficient and most of them focus on individual crystal grains. In this study, large-scale Cr2S3and Cr2Se3films with controllable thickness are successfully grown, and their crystalline qualities are confirmed by multiple characterizations. Moreover, the thickness-dependent Raman vibrations are investigated systematically, presenting slight redshift with increasing thickness. The fundamental physical properties of grown Cr2S3and Cr2Se3films, including optical bandgap, activation energy and electrical properties, are measured with different thicknesses. The 1.9 nm thick Cr2S3and Cr2Se3films show narrow optical bandgap of 0.732 and 0.672 eV, respectively. The electrical properties of Cr2S3films demonstratep-type semiconductor behaviours, while the Cr2Se3films exhibit no gate response. This work can provide a feasible method for growing large-scale Cr2S3and Cr2Se3films, and reveal fundamental information of their physical properties, which is helpful for future applications.

Evidence for Anisotropic Superconductivity Beyond Pauli Limit in Infinite-Layer Lanthanum Nickelates.

After being expected to be a promising analog to cuprates for decades, superconductivity has recently been discovered in infinite-layer nickelates, providing new opportunities to explore mechanisms of high-temperature superconductivity. However, in sharp contrast to the single-band and anisotropic superconductivity in cuprates, nickelates exhibit a multi-band electronic structure and an unexpected isotropic superconductivity as reported recently, which challenges the cuprate-like picture in nickelates. Here, it is shown that strong anisotropic magnetotransport behaviors exist in La-based nickelate films with enhanced crystallinity and superconductivity ( T c onset $T_{\rm{c}}^{{\rm{onset}}}$ = 18.8 K, T c zero $T_{\rm{c}}^{{\rm{zero}}}$ = 16.5 K). The upper critical fields are anisotropic and violate the estimated Bardeen-Cooper-Schrieffer (BCS) Pauli limit ( H Pauli , µ = 1 µ B = 1.86 × T c , H = 0 ${H}_{\mathrm{Pauli},\mu =1{\mu}_{B}}=1.86\ensuremath{\times{}}{T}_{\mathrm{c},H=0}$ ) for in-plane magnetic fields. Moreover, the anisotropic superconductivity is further manifested by the cusp-like peak of the angle-dependent Tc and the vortex motion anisotropy under external magnetic fields.

Prominent Size Effects without a Depolarization Field Observed in Ultrathin Ferroelectric Oxide Membranes.

The increasing miniaturization of electronics requires a better understanding of material properties at the nanoscale. Many studies have shown that there is a ferroelectric size limit in oxides, below which the ferroelectricity will be strongly suppressed due to the depolarization field, and whether such a limit still exists in the absence of the depolarization field remains unclear. Here, by applying uniaxial strain, we obtain pure in-plane polarized ferroelectricity in ultrathin SrTiO_{3} membranes, providing a clean system with high tunability to explore ferroelectric size effects especially the thickness-dependent ferroelectric instability with no depolarization field. Surprisingly, the domain size, ferroelectric transition temperature, and critical strain for room-temperature ferroelectricity all exhibit significant thickness dependence. These results indicate that the stability of ferroelectricity is suppressed (enhanced) by increasing the surface or bulk ratio (strain), which can be explained by considering the thickness-dependent dipole-dipole interactions within the transverse Ising model. Our study provides new insights into ferroelectric size effects and sheds light on the applications of ferroelectric thin films in nanoelectronics.

Tuning Piezoelectricity via Thermal Annealing at a Freestanding Ferroelectric Membrane.

Tuning the ferroelectric domain structure by a combination of elastic and electrostatic engineering provides an effective route for enhanced piezoelectricity. However, for epitaxial thin films, the clamping effect imposed by the substrate does not allow aftergrowth tuning and also limits the electromechanical response. In contrast, freestanding membranes, which are free of substrate constraints, enable the tuning of a subtle balance between elastic and electrostatic energies, giving new platforms for enhanced and tunable functionalities. Here, highly tunable piezoelectricity is demonstrated in freestanding PbTiO3 membranes, by varying the ferroelectric domain structures from c-dominated to c/a and a domains via aftergrowth thermal treatment. Significantly, the piezoelectric coefficient of the c/a domain structure is enhanced by a factor of 2.5 compared with typical c domain PbTiO3. This work presents a new strategy to manipulate the piezoelectricity in ferroelectric membranes, highlighting their great potential for nano actuators, transducers, sensors and other NEMS device applications.

Ultramicroporous Hydrogen-Bonded Organic Framework Material with a Thermoregulatory Gating Effect for Record Propylene Separation.

Propane/propylene separation is one of the most challenging and energy-consuming but most important tasks in the petrochemical industry. Herein, a stable hydrogen-bonded organic framework (HOF-FJU-1) was tailor-made for highly efficient propylene separation from binary C3H6/C3H8 and even seven component CH4/C2H4/C2H6/C3H6/C3H8/CO2/H2 mixtures. The temperature-controllable diffusion channels in HOF-FJU-1 have enabled the porous material to completely exclude propane to reach high-performance propylene purification under energy-efficient operation conditions. Single-crystal structural analysis revealed that the well-matched pore aperture of HOF-FJU-1 can exactly accommodate propylene molecules via multiple intermolecular interactions, exhibiting a very high propylene/propane selectivity of 616 at 333 K. The propylene purity and productivity are over 99.5% and 30.2 L kg-1 from the binary C3H6/C3H8 (50/50) mixture at 333 K. Through a follow-up column separation of C3H6/C2H4 at 353 K, not only high-purity propylene (99.5%) but also ethylene (98.3%) can be readily collected from the seven component CH4/C2H4/C2H6/C3H6/C3H8/CO2/H2 (31/10/25/10/10/1/13) cracking gas mixtures. The great potential of HOF-FJU-1 for the industrial propylene separation process has been further supported by the high stability of this porous material under different environments and straightforward processibility and regeneration feasibility.

CO2 Capture from High-Humidity Flue Gas Using a Stable Metal-Organic Framework.

The flue gas from fossil fuel power plants is a long-term stable and concentrated emission source of CO2, and it is imperative to reduce its emission. Adsorbents have played a pivotal role in reducing CO2 emissions in recent years, but the presence of water vapor in flue gas poses a challenge to the stability of adsorbents. In this study, ZIF-94, one of the ZIF adsorbents, showed good CO2 uptake (53.30 cm3/g), and the calculated CO2/N2 (15:85, v/v) selectivity was 54.12 at 298 K. Because of its excellent structural and performance stability under humid conditions, the CO2/N2 mixture was still well-separated on ZIF-94 with a separation time of 30.4 min when the relative humidity was as high as 99.2%, which was similar to the separation time of the dry gas experiments (33.2 min). These results pointed to the enormous potential applications of ZIF-94 for CO2/N2 separation under high humidity conditions in industrial settings.

Nonvolatile ferroelectric domain wall memory integrated on silicon.

Ferroelectric domain wall memories have been proposed as a promising candidate for nonvolatile memories, given their intriguing advantages including low energy consumption and high-density integration. Perovskite oxides possess superior ferroelectric prosperities but perovskite-based domain wall memory integrated on silicon has rarely been reported due to the technical challenges in the sample preparation. Here, we demonstrate a domain wall memory prototype utilizing freestanding BaTiO3 membranes transferred onto silicon. While as-grown BaTiO3 films on (001) SrTiO3 substrate are purely c-axis polarized, we find they exhibit distinct in-plane multidomain structures after released from the substrate and integrated onto silicon due to the collective effects from depolarizing field and strain relaxation. Based on the strong in-plane ferroelectricity, conductive domain walls with reading currents up to nanoampere are observed and can be both created and erased artificially, highlighting the great potential of the integration of perovskite oxides with silicon for ferroelectric domain wall memories.

Comparison of Five Protocols of Estrous Synchronization on Reproductive Performance of Hu Sheep.

The purpose of this study is to compare five protocols of estrous synchronization for Hu ewes to obtain the most effective and economical protocol, to apply the advantageous scheme in large-scale sheep farming. Healthy multiparous Hu ewes (n = 150) were randomly divided into five groups, and all ewes were administered fluorogestone acetate (FGA, 45 mg) vaginal sponge. The sponges of the first three groups (Groups I, II, and III) were removed on the 11th day, and 0.1 mg of PGF2α was injected intramuscularly on the ninth day. Group I received 6 µg of gonadotropin-releasing hormone (GnRH) by intramuscular injection at 36th h after withdrawal of the sponge. Group II was injected 330 IU of pregnant mare serum gonadotropin (PMSG) on the ninth day. The combination of 6 µg of GnRH and 330 IU of PMSG was treated in Group III at the same time as Group I and Group II. The sponges of the latter two groups (Groups IV and V) were removed on the 13th day, and 330 IU of PMSG was injected intramuscularly simultaneously. PGF2α (0.1 mg) was administered on the 12th day in Group IV. All ewes were detected for estrus at 24, 36, 48, 60, and 72 h after the sponge removal. The loss of sponge and vaginitis was recorded when the sponge was withdrawn. Cervical artificial insemination (AI) was performed with fresh semen of Dorper rams diluted with skimmed milk. After 30 days of insemination, the conception was detected with a veterinary B-ultrasound scanner. The lambing status of all ewes and the cost of drugs for estrous synchronization in each group were recorded. The results showed the following: (1) on the whole, the average percentage of estrous ewes in the period of 24-36 h and 36-48 h after removal was significantly higher than other three periods and that of the period of 60-72 h was significantly lower than the first three periods after removal; (2) there was no significant difference in percentages of estrous ewes in any of the five time periods, sponge loss rate, vaginitis rate, total percentage of estrous ewes, conception rate, single lambing rate, twinning rate, and multiple lambing rate of ewes among five protocols; (3) total percentage of estrous ewes and conception rate were more than or equal to 80% in the Groups II and III, and the twinning lamb rate of the Group II protocol was 70%; (4) there was no difference in lambing rate of ewes among Groups II, III, IV, and V; (5) the Group III had the highest drug cost of 22.5 CNY. In conclusion, considering the lambing rate, twinning lamb rate, and drug cost for estrous synchronization, Group II was the most advisable for application and promotion in large-scale sheep farms among these five protocols of estrus synchronization.

Offline and Online Social Support and Short-Form Video Addiction Among Chinese Adolescents: The Mediating Role of Emotion Suppression and Relatedness Needs.

Short-form video applications have gained worldwide popularity in recent years. Although short-form video applications encourage communication over the Internet, their popularity encourages adolescents to overindulge in them. This study aimed to explore the effects of offline and online social support (SS) for short-form video addiction (SVA), and the mediating role of emotion regulation and basic psychological needs. A total of 490 junior middle school students from China participated in the study. Structural equation modeling using a bootstrap procedure revealed that (a) offline SS and relatedness needs negatively predicted SVA, (b) pursuit of online SS and emotion suppression positively predicted SVA, (c) emotion suppression and relatedness needs were mediators between offline SS and SVA, and (d) emotion suppression was a mediator between the pursuit of online SS and SVA. These findings provide valuable insight into SVA and will help develop effective strategies for the prevention of SVA.

Substituent-Induced Electron-Transfer Strategy for Selective Adsorption of N2 in MIL-101(Cr)-X Metal-Organic Frameworks.

N2 removal is of great significance in high-purity O2 production and natural gas purification. Here, we present a substituent-induced electron-transfer strategy for improving N2 capture performance by controlling the Lewis acidity of Cr(III) metal unsaturated sites in Cr-based metal-organic frameworks. With the enhancement of the electron-withdrawing ability of the modified group on terephthalic acid (-NO2 > -CH3), the N2 adsorption ability of MIL-101(Cr)-X was improved significantly. For MIL-101(Cr)-NO2, the adsorption enthalpy of N2 at zero coverage was 30.01 kJ/mol, which was much larger than that of MIL-101(Cr)-CH3 (14.31 kJ/mol). In situ infrared spectroscopy studies, Bader charges, and density functional theory calculations showed that the presence of -NO2 could enhance the Lewis acidity of Cr(III) metal unsaturated sites, which resulted in a strong interaction affinity for N2. The adsorption isotherms indicated that MIL-101(Cr)-NO2 had an excellent N2/O2 (79/21, v/v) selectivity of up to 10.8 and a good N2/CH4 separation performance (SN2/CH4 = 2.8, 298 K, 1 bar). Breakthrough curves showed that MIL-101(Cr)-NO2 had great potential for the efficient separation of N2/O2 and N2/CH4.

K-Chabazite Zeolite Nanocrystal Aggregates for Highly Efficient Methane Separation.

Methane (CH4 ) enrichment and purification is of great significance for increasing the heating value of unconventional natural gas sources and curtailing its effect on global warming. For a long time, commercial adsorbents for CH4 separation have been hampered by low adsorption capacities, sub-optimal adsorption selectivities, or slow diffusion rates, which have significantly restricted separation productivity. Herein, we report a facile and green seed-passaging method to fabricate donut-like macro-meso-micro hierarchical zeolite K-Chabazite nanocrystal aggregates. This consecutive seed-inducing method requires no organic template. By utilizing this unique nanocrystallization technique, the CH4 adsorption capacity, gas diffusion rate, and separation productivity of the resultant material are dramatically increased compared with those of commercially available adsorbents, thus setting a new benchmark in CH4 /N2 separation. More importantly, production of this adsorbent can be easily scaled-up to the order of 100 kg using readily available raw materials in this environmentally friendly synthetic route, enabling potential industrial implementation.

Construction of a Porous Metal-Organic Framework with a High Density of Open Cr Sites for Record N2 /O2 Separation.

The removal of low concentration N2 is of great significance and challenging in the industrial production of high-purity O2 . Herein, a chromium-based metal-organic framework, namely, TYUT-96Cr, is reported, which has an unprecedented N2 capture capacity of 37.46 cm3 cm-3 and N2 /O2 (5:95, v/v) selectivity up to 26.95 (298 K and 1 bar), thus setting new benchmarks for all reported metal-organic frameworks and commercially used ones (Li-LSX and 13X). Breakthrough experiments reveal that N2 can be directly extracted from various N2 /O2 (79:21, 50:50, 5:95, and 1:99, v/v) mixtures by this material, affording a record-high O2 -production scale with 99.99% purity. Density functional theory calculations and in situ infrared spectroscopy studies demonstrate that the high-density open Cr (III) sites in TYUT-96Cr can behave as effective Lewis acidic sites, thus resulting in a strong affinity toward N2 . The high N2 adsorption selectivity, exceptional separation performance, and ultrahigh structural stability render this porous material with great potential for this important industrial application.

Flavonoid GL-V9 suppresses invasion and migration of human colorectal cancer cells by inhibiting PI3K/Akt and MMP-2/9 signaling.

Tumor distant metastasis is the primary cause of death in colorectal cancer (CRC) patients. GL-V9 is a newly synthesized flavonoid derivative with several beneficial biological functions including anti-tumor and anti-inflammation. However, the anti-metastatic effect of GL-V9 and related mechanisms in CRC remains unknown. In this study, the anti-invasive and anti-migratory activities of GL-V9 were investigated in CRC cells. Using MTT assay, cell wound healing assay, and transwell migration assay, we showed that GL-V9 suppressed CRC cell viability, migration, and invasion in a concentration-dependent manner. In addition, the protein expression levels as well as activities of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) were significantly reduced after GL-V9 treatment. Further analysis of the underlying mechanism revealed that GL-V9 inhibited PI3K/Akt signaling pathway upstream of MMP-2 and MMP-9. In conclusion, our study demonstrated that GL-V9 could suppress CRC cell invasion and migration through PI3K/Ak and MMP-2/9 axis. Therefore, GL-V9 might be a potential novel therapeutic agent against CRC metastasis.

The efficient separation of N2O/CO2 using unsaturated Fe2+ sites in MIL-100Fe.

It is a big challenge to separate N2O from CO2 using adsorption because they have similar physical properties. The Fe3+-F- site in MIL-100Fe transforms to an unsaturated Fe2+ site under high-temperature activation (300 °C), and the target sorbent MIL-100Fe-300 exhibits the biggest difference in CO2 and N2O adsorption capacity, and the selectivity of N2O/CO2 (50%/50%) is up to 3.00 at 298 K. According to DFT calculations, the original Fe3+-F- site has strong interaction with CO2, but the open Fe2+ site has a stronger interaction with N2O. Through a breakthrough experiment, it was confirmed that MIL-100Fe-300 has the best N2O/CO2 separation performance, making it potentially a useful material in industry.