Abstract
Metal–organic rotaxane compounds (MORCs) with supramolecular (pseudo)rotaxane motifs as main structures have inherent dynamic character, but their potential as responsive molecular machines ...is largely hampered by poor responsiveness to external stimuli. In this study, using a multi‐functionalized pseudorotaxane linker that combines two kinds of functionalities, a novel MORC,
U‐bpybc‐CB8
(U refers to uranyl, bpybc refers to 1, 1’‐bis(4‐carboxybenzyl)‐4, 4’‐bipyridinium, and CB8 is cucurbit8uril), with multi‐responsive capability that can respond to both light and thermal stimuli, is reported. The characterization, combining spectra measurements and single‐crystal X‐ray diffraction, shows that, due to the involvement of viologen‐functionalized flexible organic dicarboxylate guest molecule in the CB8‐ involved pseudorotaxane ligand, the resultant uranyl‐based MORC exhibits photochromic behavior after UV or visible light irradiation. More interestingly, it is revealed that the exceptional thermal response of
U‐bpybc‐CB8
as temperature increases from 170 to 270 K, i.e., volume expansion followed by contraction after the inflection temperature of ≈230 K, can be stemmed from the lattice flexibility of this metal–organic supramolecular network. The dual responsiveness of MORCs reported here demonstrates the potential of such supramolecular assemblies as smart molecular components like sensors and switches that respond to light irradiation or temperature changes.
It is an ongoing goal to achieve the effective regulation of the thermal expansion properties of materials. In this work, we propose a method for incorporating host-guest complexation into a ...framework structure and construct a flexible cucurbit8uril uranyl-organic polythreading framework, U
(bcbpy)
(CB8). U
(bcbpy)
(CB8) can undergo huge negative thermal expansion (NTE) and has a large volumetric coefficient of -962.9 × 10
K
within the temperature range of 260 K to 300 K. Crystallographic snapshots of the polythreading framework at various temperatures reveal that, different from the intrinsic transverse vibrations of the subunits of metal-organic frameworks (MOFs) that experience NTE
a well-known hinging model, the remarkable NTE effect observed here is the result of a newly-proposed thermally induced relaxation process. During this process, an extreme spring-like contraction of the flexible CB8-based pseudorotaxane units, with an onset temperature of ∼260 K, follows a period of cumulative expansion. More interestingly, compared with MOFs that commonly have relatively strong coordination bonds, due to the difference in the structural flexibility and adaptivity of the weakly bonded U
(bcbpy)
(CB8) polythreading framework, U
(bcbpy)
(CB8) shows unique time-dependent structural dynamics related to the relaxation process, the first time this has been reported in NTE materials. This work provides a feasible pathway for exploring new NTE mechanisms by using tailored supramolecular host-guest complexes with high structural flexibility and has promise for the design of new kinds of functional metal-organic materials with controllable thermal responsive behaviour.
: GBM astrocytes may adopt fetal astrocyte transcriptomic signatures involved in brain development and migration programs to facilitate diffuse tumor infiltration. Our previous data show that ETS ...variant 6 (ETV6) is highly expressed in human GBM and fetal astrocytes compared to normal mature astrocytes. We hypothesized that ETV6 played a role in GBM tumor progression.
: Expression of ETV6 was first examined in two American and three Chinese tissue microarrays. The correlation between ETV6 staining intensity and patient survival was calculated, followed by validation using public databases-TCGA and REMBRANDT. The effect of ETV6 knockdown on glioma cell proliferation (EdU), viability (AnnexinV labeling), clonogenic growth (colony formation), and migration/invasion (transwell assays) in GBM cells was tested. RNA sequencing and Western blot were performed to elucidate the underlying molecular mechanisms.
: ETV6 was highly expressed in GBM and associated with an unfavorable prognosis. ETV6 silencing in glioma cells led to increased apoptosis or decreased proliferation, clonogenicity, migration, and invasion. RNA-Seq-based gene expression and pathway analyses revealed that ETV6 knockdown in U251 cells led to the upregulation of genes involved in extracellular matrix organization, NF-κB signaling, TNF-mediated signaling, and the downregulation of genes in the regulation of cell motility, cell proliferation, PI3K-AKT signaling, and the Ras pathway. The downregulation of the PI3K-AKT and Ras-MAPK pathways were further validated by immunoblotting.
: Our findings suggested that ETV6 was highly expressed in GBM and its high expression correlated with poor survival. ETV6 silencing decreased an aggressive in vitro phenotype probably via the PI3K-AKT and Ras-MAPK pathways. The study encourages further investigation of ETV6 as a potential therapeutic target of GBM.
As an aprotic O-donor ligand, 4,4′-bipyridine N,N′-dioxide (DPO) shows good potential for the preparation of uranyl coordination compounds. In this work, by regulating reactant compositions and ...synthesis conditions, diverse coordination assembly between uranyl and DPO under different reaction conditions was achieved in the presence of other coexisting O-donors. A total of ten uranyl-DPO compounds, U-DPO-1 to U-DPO-10, have been synthesized by evaporation or hydro/solvothermal treatment, and the possible competition and cooperation of DPO with other O-donors for the formation of these uranyl-DPO compounds are discussed. Starting with an aqueous solution of uranyl nitrate, it is found that an anionic nitrate or hydroxyl group is involved in the coordination sphere of uranyl in U-DPO-1 ((UO2)(NO3)2(H2O)2·(DPO)), U-DPO-2 ((UO2)(NO3)2(DPO)), and U-DPO-3 ((UO2)(DPO)(μ2-OH)2), where DPO takes three different kinds of coordination modes, i.e. uncoordinated, monodentate, and biconnected. The utilization of UO2(CF3SO3)2 in acetonitrile, instead of an aqueous solution of uranyl nitrate, precludes the participation of nitrate and hydroxyl, and ensures the engagement of DPO ligands (4–5 DPO ligands for each uranyl) in a uranyl coordination sphere of U-DPO-4 ((UO2)(CF3SO3)(DPO)2(CF3SO3)), U-DPO-5 (UO2(H2O)(DPO)2(CF3SO3)2) and U-DPO-6 ((UO2)(DPO)2.5(CF3SO3)2). Moreover, when combined with anionic carboxylate ligands, terephthalic acid (H2TPA), isophthalic acid (H2IPA), and succinic acid (H2SA), DPO works well with them to produce four mixed-ligand uranyl compounds with similar structures of two-dimensional (2D) networks or three-dimensional (3D) frameworks, U-DPO-7 ((UO2)(TPA)(DPO)), U-DPO-8 ((UO2)2(DPO)(IPA)2·0.5H2O), U-DPO-9 ((UO2)(SA)(DPO)·H2O), and U-DPO-10 ((UO2)2(μ2-OH)(SA)1.5(DPO)). Density functional theory (DFT) calculations conducted to probe the bonding features between uranyl ions and different O-donor ligands show that the bonding ability of DPO is better than that of anionic CF3SO3 –, nitrate, and a neutral H2O molecule and comparable to that of an anionic carboxylate group. Characterization of physicochemical properties of U-DPO-7 and U-DPO-10 with high phase purity including infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and luminescence properties is also provided.
Purpose： To investigate the usefulness of three-dimensional （3D） printing in complex spinal surgery. Methods： The study was conducted from October 2014 to March 2015 in Shenzhen Second Peoples＇ ...Hospital and 4 cases of complex severe spinal disorders were selected from our department. Among them one patient combined with congenital scoliosis, one with atlas neoplasm, one with atlantoaxial dislocation, and the rest one with atlantoaxial fracture-dislocation. The data of the diseased region was collected from computerized tomography scans for 3D digital reconstruction and rapid prototyping to prepare photosensitive resin models, which were applied in the treatment of these cases. Results： The use of 3D models reduced operating time and intraoperative blood loss as well as the risk of postoperative complications. Furthermore, no pedicle penetrations or screw misplacement occurred according to the postoperative planar radiographic images. Conclusion： The tactile models from 3D printing allow direct observation and measurement, helping the orthopedists to have accurate morphometric information to provide personalized surgical planning and better communication with the patient and coworkers. Moreover, the photosensitive resin models can also guide the actual surgery with the drilling of pedicle screws and safe resection of tumor.
In this paper, based on gauge transformation of Lax pairs, we construct an
N
-fold Darboux transformation for the discrete Ragnisco–Tu equation which is a typical member in the Ragnisco–Tu hierarchy. ...By using the
N
-fold Darboux transformation, new multi-soliton solutions of the discrete Ragnisco–Tu equation can be directly constructed starting from a seed solution.
It is an ongoing goal to achieve the effective regulation of the thermal expansion properties of materials. In this work, we propose a method for incorporating hostguest complexation into a framework ...structure and construct a flexible cucurbit8uril uranyl-organic polythreading framework, U
3
(bcbpy)
3
(CB8). U
3
(bcbpy)
3
(CB8) can undergo huge negative thermal expansion (NTE) and has a large volumetric coefficient of 962.9 10
6
K
1
within the temperature range of 260 K to 300 K. Crystallographic snapshots of the polythreading framework at various temperatures reveal that, different from the intrinsic transverse vibrations of the subunits of metalorganic frameworks (MOFs) that experience NTE
via
a well-known hinging model, the remarkable NTE effect observed here is the result of a newly-proposed thermally induced relaxation process. During this process, an extreme spring-like contraction of the flexible CB8-based pseudorotaxane units, with an onset temperature of 260 K, follows a period of cumulative expansion. More interestingly, compared with MOFs that commonly have relatively strong coordination bonds, due to the difference in the structural flexibility and adaptivity of the weakly bonded U
3
(bcbpy)
3
(CB8) polythreading framework, U
3
(bcbpy)
3
(CB8) shows unique time-dependent structural dynamics related to the relaxation process, the first time this has been reported in NTE materials. This work provides a feasible pathway for exploring new NTE mechanisms by using tailored supramolecular hostguest complexes with high structural flexibility and has promise for the design of new kinds of functional metalorganic materials with controllable thermal responsive behaviour.
A highly flexible uranyl-organic polythreading framework enabled by cucurbit8uril-based hostguest complexation exhibits remarkable negative thermal expansion behaviour through a relaxation-related mechanism.
Schizophrenia (SCZ) is a severe mental illness that affects several brain domains with relation to cognition and behaviour. SCZ symptoms are typically classified into three categories, namely, ...positive, negative, and cognitive. The etiology of SCZ is thought to be multifactorial and poorly understood. Accumulating evidence has indicated abnormal synaptic plasticity and cognitive impairments in SCZ. Synaptic plasticity is thought to be induced at appropriate synapses during memory formation and has a critical role in the cognitive symptoms of SCZ. Many factors, including synaptic structure changes, aberrant expression of plasticity-related genes, and abnormal synaptic transmission, may influence synaptic plasticity and play vital roles in SCZ. In this article, we briefly summarize the morphology of the synapse, the neurobiology of synaptic plasticity, and the role of synaptic plasticity, and review potential mechanisms underlying abnormal synaptic plasticity in SCZ. These abnormalities involve dendritic spines, postsynaptic density, and long-term potentiation-like plasticity. We also focus on cognitive dysfunction, which reflects impaired connectivity in SCZ. Additionally, the potential targets for the treatment of SCZ are discussed in this article. Therefore, understanding abnormal synaptic plasticity and impaired cognition in SCZ has an essential role in drug therapy.
BACKGROUNDSchizophrenia afflicts 1% of the world population. Clinical studies suggest that schizophrenia patients may have an imbalance of mitochondrial energy metabolism via inhibition of ...mitochondrial complex I activity. Moreover, recent studies have shown that ERVWE1 is also a risk factor for schizophrenia. Nevertheless, there is no available literature concerning the relationship between complex I deficits and ERVWE1 in schizophrenia. Identifying risk factors and blood-based biomarkers for schizophrenia may provide new guidelines for early interventions and prevention programs. AIMTo address novel potential risk factors and the underlying mechanisms of mitochondrial complex I deficiency caused by ERVWE1 in schizophrenia. METHODSQuantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay were used to detect differentially expressed risk factors in blood samples. Clinical statistical analyses were performed by median analyses and Mann-Whitney U analyses. Spearman's rank correlation was applied to examine the correlation between different risk factors in blood samples. qPCR, western blot analysis, and luciferase assay were performed to confirm the relationship among ERVWE1, cytoplasmic polyadenylation element-binding protein 1 (CPEB1), NADH dehydrogenase ubiquinone flavoprotein 2 (NDUFV2), and NDUFV2 pseudogene (NDUFV2P1). The complex I enzyme activity microplate assay was carried out to evaluate the complex I activity induced by ERVWE1. RESULTSHerein, we reported decreasing levels of CPEB1 and NDUFV2 in schizophrenia patients. Further studies showed that ERVWE1 was negatively correlated with CPEB1 and NDUFV2 in schizophrenia. Moreover, NDUFV2P1 was increased and demonstrated a significant positive correlation with ERVWE1 and a negative correlation with NDUFV2 in schizophrenia. In vitro experiments disclosed that ERVWE1 suppressed NDUFV2 expression and promoter activity by increasing NDUFV2P1 level. The luciferase assay revealed that ERVWE1 could enhance the promoter activity of NDUFV2P1. Additionally, ERVWE1 downregulated the expression of CPEB1 by suppressing the promoter activity, and the 400 base pair sequence at the 3' terminus of the promoter was the minimum sequence required. Advanced studies showed that CPEB1 participated in regulating the NDUFV2P1/NDUFV2 axis mediated by ERVWE1. Finally, we found that ERVWE1 inhibited complex I activity in SH-SY5Y cells via the CPEB1/NDUFV2P1/NDUFV2 signaling pathway. CONCLUSIONIn conclusion, CPEB1 and NDUFV2 might be novel potential blood-based biomarkers and pathogenic factors in schizophrenia. Our findings also reveal a novel mechanism of ERVWE1 in the etiology of schizophrenia.
Cu/Al composites are of vital importance in industrial applications because of their numerous advantages. The influence of bond-ing temperature and cooling rate on the microstructure and morphology ...of Cu/Al composites was investigated in this paper. The interfacial morphology and constituent phases at the Cu/Al interface were analyzed by optical microscopy and field-emission scanning electron mi-croscopy equipped with energy-dispersive X-ray spectroscopy. The results indicate that effective Cu-Al bonding requires a higher bonding temperature to facilitate interdiffusion between the two metals. The microstructural characteristics are associated with various bonding tem-peratures, which impact the driving force of interdiffusion. It is observed that cooling rate exerts a significant influence on the morphology and amount of the intermetallic compounds at the interfacial region. Meanwhile, microhardness measurements show that hardness varies with the bonding temperature and rate of cooling.
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