The rational design of artificial solid-state nanopores is of great importance in the discovery of intriguing ion transport phenomena. 2D metal-organic framework (2D MOF) nanosheets with single crystallinity, aligned nanochannels, ultrathin thickness, and diverse functionalities are highly potential solid-state nanopores. An electrophoretic method is developed to successfully fabricate MOF nanopores supported by SiN x substrate, which is confirmed by high-resolution transmission electron microscopy. A giant gap around 4 V together with ionic current rectification is discovered in nonlinear voltage-activated current-voltage curves, revealing the synergy of the hydrophobic effect and charge effect in MOF nanopores. The charge effect embodies the different contribution current which results from the enrichment and depletion of ions in MOF nanopores by COMSOL simulation. Moreover, 2D MOF nanosheets with different surface charges, hydrophobicity, and pore sizes demonstrate the universality of nanopore fabrication and further confirm the synergistic mechanism. The nonlinear ion transport in the ultrathin MOF nanosheets will provide an opportunity to explore further applications in solid-state nanopores.

A series of lanthanide-organic framework coordination polymers, {[La(2)(TDC)(2)(NO(3))(H(2)O)(4)](OH)·5H(2)O}(n) (1) and [Ln(TDC)(NO(3))(H(2)O)](n) (TDC = thiophene- 2, 5- dicarboxylic acid; Ln = Nd(2), Sm(3), Eu(4), Gd(5), Tb(6), Dy(7), Ho(8), Er(9), Yb(10)) have been synthesized by solvothermal reaction and characterized by elemental analysis, FT-IR, TG analysis, single-crystal X-ray diffraction and power X-ray diffraction. The single-crystal X-ray diffraction analysis results show that 1 displays a 3-D porous framework with (3,7)-connected {4(10).6(11)}{4(3)} topology. The compounds 2-10 crystallized in the same P2(1)/c space group and exhibits a (3,6)-connected {4.6(2)}(2){4(2).6(10).8(3)} topology, Right-handed and left-handed helical chains coexist in the 2-D layer structure. The luminescence properties of 2-10 and the magnetic properties of 5,7,8,9 were investigated.

Background This study investigated the effect of melatonin (MT) on cell cycle (G1/S/G2/M) of parthenogenetic zygotes developed from vitrified-warmed mouse metaphase II (MII) oocytes and elucidated the potential mechanism of MT action in the first cleavage of embryos. Results After vitrification and warming, oocytes were parthenogenetically activated (PA) and in vitro cultured (IVC). Then the spindle morphology and chromosome segregation in oocytes, the maternal mRNA levels of genes including Miss, Doc1r, Setd2 and Ythdf2 in activated oocytes, pronuclear formation, the S phase duration in zygotes, mitochondrial function at G1 phase, reactive oxygen species (ROS) level at S phase, DNA damage at G2 phase, early apoptosis in 2-cell embryos, cleavage and blastocyst formation rates were evaluated. The results indicated that the vitrification/warming procedures led to following perturbations 1) spindle abnormalities and chromosome misalignment, alteration of maternal mRNAs and delay in pronucleus formation, 2) decreased mitochondrial membrane potential (MMP) and lower adenosine triphosphate (ATP) levels, increased ROS production and DNA damage, G1/S and S/G2 phase transition delay, and delayed first cleavage, and 3) increased early apoptosis and lower levels of cleavage and blastocyst formation. Our results further revealed that such negative impacts of oocyte cryopreservation could be alleviated by supplementation of warming, recovery, PA and IVC media with 10− 9 mol/L MT before the embryos moved into the 2-cell stage of development. Conclusions MT might promote cell cycle progression via regulation of MMP, ATP, ROS and maternal mRNA levels, potentially increasing the first cleavage of parthenogenetic zygotes developed from vitrified–warmed mouse oocytes and their subsequent development.

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Solid-state nanopore as a versatile alternative to biological nanopore has grown tremendously over the last two decades. It exhibits unique characteristics including mechanical robustness, thermal and chemical stability, easy modifications...