Highly porous metal-organic frameworks (MOFs), which have undergone exciting developments over the past few decades, show promise for a wide range of applications. However, many studies indicate that ...they suffer from significant stability issues, especially with respect to their interactions with water, which severely limits their practical potential. Here we demonstrate how the presence of 'sacrificial' bonds in the coordination environment of its metal centres (referred to as hemilability) endows a dehydrated copper-based MOF with good hydrolytic stability. On exposure to water, in contrast to the indiscriminate breaking of coordination bonds that typically results in structure degradation, it is non-structural weak interactions between the MOF's copper paddlewheel clusters that are broken and the framework recovers its as-synthesized, hydrated structure. This MOF retained its structural integrity even after contact with water for one year, whereas HKUST-1, a compositionally similar material that lacks these sacrificial bonds, loses its crystallinity in less than a day under the same conditions.
The assembly–disassembly–organization–reassembly (ADOR) process has been used to disassemble a parent zeolite with the UOV structure type and then reassemble the resulting layers into a novel ...structure, IPC‐12. The structure of the material has previously been predicted computationally and confirmed in our experiments using X‐ray diffraction and atomic resolution STEM‐HAADF electron microscopy. This is the first successful application of the ADOR process to a material with porous layers.
A germane assembly: The synthesis of a new zeolite IPC‐12 using the assembly–disassembly–organization–reassembly (ADOR) transformation of a germanosilicate zeolite with the UOV topology is reported.
An increasing number of studies are describing potential uses of circulating tumour DNA (ctDNA) in the care of patients with colorectal cancer. Owing to this rapidly developing area of research, the ...Colon and Rectal-Anal Task Forces of the United States National Cancer Institute convened a panel of multidisciplinary experts to summarize current data on the utility of ctDNA in the management of colorectal cancer and to provide guidance in promoting the efficient development and integration of this technology into clinical care. The panel focused on four key areas in which ctDNA has the potential to change clinical practice, including the detection of minimal residual disease, the management of patients with rectal cancer, monitoring responses to therapy, and tracking clonal dynamics in response to targeted therapies and other systemic treatments. The panel also provides general guidelines with relevance for ctDNA-related research efforts, irrespective of indication.
Ferroelectricity features the electrical switching of off-centered ions between the potential double well of the non-centrosymmetric lattice, while ionic conduction requires long-range hopping of ...ions across the lattice periodic potentials. The two seemingly mutually exclusive phenomena become strongly intertwined at the nanoscale in electrochemically active materials. However, the intrinsic coupling between ferroelectric switching and ionic activities in bulk crystalline materials remains largely unexplored. Here, we report anomalous polarization switching characteristics of a van der Waals (vdW) layered ferroelectric ionic conductor, CuInP
2
S
6
. By synergistic polarization switching and dielectric spectroscopy studies in both temperature and frequency domains, we reveal that the polarization switching kinetics of this compound is ionic-conduction-limited, due to the strong electrostatic interaction between ferroelectric and ionic defect dipoles. The crucial role of thermally-activated displacive instability of Cu ions is confirmed by the single-crystal X-ray crystallography results. The findings provide fundamental insight into the ionic kinetics under an electric field in crystals with coexisting dipole order (ferroelectricity) and disorder (ionic defect and conductivity). Last but not least, we demonstrate that the spontaneous ionic defect-polarization interlock can lead to permanent ferroelectric retention, which is essential for information storage.
Ionic conduction in a ferroelectric leads to anomalous polarization switching kinetics but prevents retention failure.
The hydrothermal synthesis of a zeolite with properties suitable for use in the assembly–disassembly–organization–reassembly (ADOR) process was designed, and a zeolite called SAZ-1 was successfully ...prepared. This zeolite was then used as a parent in the ADOR process, and two new daughter zeolites, IPC-15 and IPC-16, were prepared. The X-ray powder diffraction patterns of the new zeolites match well with those predicted using computational methods. The three materials form an isoreticular series with decreasing pores size from 14-ring to 12-ring to 10-ring.
Recent research on piezoelectric materials is predominantly devoted to enhancing the piezoelectric coefficient, but overlooks its sign, largely because almost all of them exhibit positive ...longitudinal piezoelectricity. The only experimentally known exception is ferroelectric polymer poly(vinylidene fluoride) and its copolymers, which condense via weak van der Waals (vdW) interaction and show negative piezoelectricity. Here we report quantitative determination of giant intrinsic negative longitudinal piezoelectricity and electrostriction in another class of vdW solids-two-dimensional (2D) layered ferroelectric CuInP
S
. With the help of single crystal x-ray crystallography and density-functional theory calculations, we unravel the atomistic origin of negative piezoelectricity in this system, which arises from the large displacive instability of Cu ions coupled with its reduced lattice dimensionality. Furthermore, the sizable piezoelectric response and negligible substrate clamping effect of the 2D vdW piezoelectric materials warrant their great potential in nanoscale, flexible electromechanical devices.
To assess the compliance of air quality regulations, the Environmental Protection Agency (EPA) must know if a site exceeds a pre-specified level. In the case of ozone, the level for compliance is ...fixed at 75 parts per billion, which is high, but not extreme at all locations. We present a new space-time model for threshold exceedances based on the skew-t process. Our method incorporates a random partition to permit long-distance asymptotic independence while allowing for sites that are near one another to be asymptotically dependent, and we incorporate thresholding to allow the tails of the data to speak for themselves. We also introduce a transformed AR(1) time-series to allow for temporal dependence. Finally, our model allows for high-dimensional Bayesian inference that is comparable in computation time to traditional geostatistical methods for large data sets. We apply our method to an ozone analysis for July 2005, and find that our model improves over both Gaussian and max-stable methods in terms of predicting exceedances of a high level.
Using NMR to probe transient binding of Aβ1-40 monomers to fibers, we find partially bound conformations with the highest degree of interaction near F19-K28 and a lesser degree of interaction near ...the C-terminus (L34-G37). This represents a shift away from the KLVFFA recognition sequence (residues 16-21) currently used for inhibitor design.
Amine-containing polymers are considered to be promising CO2 capture materials. Considerable research effort has been invested in designing and preparing new materials with high surface area and ...amine content. In this work, a series of nanoporous highly crosslinked polymers (HCPs) with covalently bonded amines were prepared by post-modification of highly crosslinked divinylbenzene-maleic anhydride (DVB-MAH) copolymer with various diamines. The successful incorporation of the diamines was confirmed using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and elemental analysis. The resulting amine-containing HCPs possessed both micropores and mesopores, and they exhibited BET surface area of 183–500 m2/g. The CO2 capture capacity of these polymers varied in relation to their surface areas and amine contents. The chemistry described in this report provides a facile synthetic route to obtain new amine-containing polymer particles as potential solid sorbents for acidic gases such as carbon dioxide.
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•Nanoporous highly crosslinked DVB-MAH was synthesized using suspension polymerization with BET surface area of 667 m2/g.•Multiamines are covalently bonded to nanoporous DVB-MAH by a two-step post-modification.•The amine-containing polymers have surface areas of 183–500 m2/g and with considerable CO2 uptakes.
T cell responses to allogeneic major histocompatibility complex antigens present a formidable barrier to organ transplantation, necessitating long-term immunosuppression to minimize rejection. ...Chronic rejection and drug-induced morbidities are major limitations that could be overcome by allograft tolerance induction. Tolerance was first intentionally induced in humans via combined kidney and bone marrow transplantation (CKBMT), but the mechanisms of tolerance in these patients are incompletely understood. We now establish an assay to identify donor-reactive T cells and test the role of deletion in tolerance after CKBMT. Using high-throughput sequencing of the T cell receptor B chain CDR3 region, we define a fingerprint of the donor-reactive T cell repertoire before transplantation and track those clones after transplant. We observed posttransplant reductions in donor-reactive T cell clones in three tolerant CKBMT patients; such reductions were not observed in a fourth, nontolerant, CKBMT patient or in two conventional kidney transplant recipients on standard immunosuppressive regimens. T cell repertoire turnover due to lymphocyte-depleting conditioning only partially accounted for the observed reductions in tolerant patients; in fact, conventional transplant recipients showed expansion of circulating donor-reactive clones, despite extensive repertoire turnover. Moreover, loss of donor-reactive T cell clones more closely associated with tolerance induction than in vitro functional assays. Our analysis supports clonal deletion as a mechanism of allograft tolerance in CKBMT patients. The results validate the contribution of donor-reactive T cell clones identified before transplant by our method, supporting further exploration as a potential biomarker of transplant outcomes.
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