A new technique is developed to directly grow Cu nanowire (CuNW) on Si substrate with electro-chemical deposition to produce height-controlled hydrophilic nanowired surfaces for enhancing pool ...boiling performance. For broader heat transfer applications, CuNW and Si nanowires (SiNW) with various nanowire heights were fabricated and examined under pool boiling with water. The heat transfer performance of the samples with NW arrays is enhanced with increasing NW heights regardless of the NW materials. The surface with the tallest NW structure (35 μm-tall SiNW) yielded a heat flux of 134 W/cm
2 at 23 K wall superheat, about 300% higher than a plain Si surface at the same wall superheat.
► A new technique is developed to directly grow copper nanowire on silicon substrate. ► Increasing nanowire height improves boiling performance. ► Optimal results were obtained in pool boiling with 35 nm long nanowires.
Abstract
Topological superconductors (TSCs) are unconventional superconductors with bulk superconducting gap and in-gap Majorana states on the boundary that may be used as topological qubits for ...quantum computation. Despite their importance in both fundamental research and applications, natural TSCs are very rare. Here, combining state of the art synchrotron and laser-based angle-resolved photoemission spectroscopy, we investigated a stoichiometric transition metal dichalcogenide (TMD), 2M-WS
2
with a superconducting transition temperature of 8.8 K (the highest among all TMDs in the natural form up to date) and observed distinctive topological surface states (TSSs). Furthermore, in the superconducting state, we found that the TSSs acquired a nodeless superconducting gap with similar magnitude as that of the bulk states. These discoveries not only evidence 2M-WS
2
as an intrinsic TSC without the need of sensitive composition tuning or sophisticated heterostructures fabrication, but also provide an ideal platform for device applications thanks to its van der Waals layered structure.
We report on the highest energy photons from the Crab Nebula observed by the Tibet air shower array with the underground water-Cherenkov-type muon detector array. Based on the criterion of a muon ...number measured in an air shower, we successfully suppress 99.92% of the cosmic-ray background events with energies E>100 TeV. As a result, we observed 24 photonlike events with E>100 TeV against 5.5 background events, which corresponds to a 5.6σ statistical significance. This is the first detection of photons with E>100 TeV from an astrophysical source.
The tumor-suppressor protein p53 is tightly controlled in normal cells by its two negative regulators--the E3 ubiquitin ligase MDM2 and its homolog MDMX. Under stressed conditions such as DNA damage, ...p53 escapes MDM2- and MDMX-mediated functional inhibition and degradation, acting to prevent damaged cells from proliferating through induction of cell cycle arrest, DNA repair, senescence or apoptosis. Ample evidence suggests that stress signals induce phosphorylation of MDM2 and MDMX, leading to p53 activation. However, the structural basis of stress-induced p53 activation remains poorly understood because of the paucity of technical means to produce site-specifically phosphorylated MDM2 and MDMX proteins for biochemical and biophysical studies. Herein, we report total chemical synthesis, via native chemical ligation, and functional characterization of (24-108)MDMX and its Tyr99-phosphorylated analog with respect to their ability to interact with a panel of p53-derived peptide ligands and PMI, a p53-mimicking but more potent peptide antagonist of MDMX, using FP and surface plasmon resonance techniques. Phosphorylation of MDMX at Tyr99 weakens peptide binding by approximately two orders of magnitude. Comparative X-ray crystallographic analyses of MDMX and of pTyr99 MDMX in complex with PMI as well as modeling studies reveal that the phosphate group of pTyr99 imposes extensive steric clashes with the C-terminus of PMI or p53 peptide and induces a significant lateral shift of the peptide ligand, contributing to the dramatic decrease in the binding affinity of MDMX for p53. Because DNA damage activates c-Abl tyrosine kinase that phosphorylates MDMX at Tyr99, our findings afford a rare glimpse at the structural level of how stress-induced MDMX phosphorylation dislodges p53 from the inhibitory complex and activates it in response to DNA damage.
Coal and rock mass bear loads together in underground engineering such as coal mining and roadway support, resulting in different mechanical properties from those of pure coal and rock mass. ...Accurately obtaining the mechanical properties of coal in coal-rock combined body can help to properly understand the deformation and failure characteristics of the underground coal mass. First, an experimental method to obtain the stress and strain of coal in coal-rock combined samples using strain gauges was proposed and validated. Then, tests on thirteen types of coal-rock combined samples were conducted. The results show that the rock experienced a strain recovery and played a loading effect on the failure of coal when coal-rock samples failed. The compressive strength of coal in the sample increased with the rock strength, and decreased with the coal-rock height ratio. Furthermore, two damage constitutive models of coal were established by serially connecting one damage body with one or two Newton body(s), to reveal the influences of rock(s) on the mechanical behavior of coal in coal-rock samples. Finally, test results were fitted using the two models. It was showed that the two models can accurately describe the stress-strain curves of coal in coal-rock samples and reflect the influences of rock(s), coal-rock combination form and coal-rock height ratio. The fitting constants of the two models have clear physical meanings and can be easily obtained, which are expected to be widely used in underground engineering.
•A test method to obtain the stress and strain of coal in coal-rock combined samples is proposed and its validation is conducted.•Tests on the mechanical properties of coal in coal-rock combination are conducted.•The properties of coal in coal-rock combination should be used in.•Two damage constitutive models for coal in coal-rock combined samples are developed.•Fitting results verify the validation of the two constitutive models.
Recent evidence indicates that long noncoding RNAs (lncRNAs) have a critical role in the regulation of cellular processes such as differentiation, proliferation, and metastasis. These lncRNAs are ...dysregulated in a variety of cancers and many function as tumor suppressors; however, the regulatory factors involved in silencing lncRNA transcription are poorly understood. In this study, we showed that epigenetic silencing of lncRNA SPRY4 intronic transcript 1 (SPRY4-IT1) occurs in non-small-cell lung cancer (NSCLC) cells through direct transcriptional repression mediated by the Polycomb group protein enhancer of zeste homolog 2 (EZH2). SPRY4-IT1 is derived from an intron within SPRY4, and is upregulated in melanoma cells; knockdown of its expression leads to cell growth arrest, invasion inhibition, and elevated rates of apoptosis. Upon depletion of EZH2 by RNA interference, SPRY4-IT1 expression was restored, and transfection of SPRY4-IT1 into NSCLC cells resulted in a significant antitumoral effect, both in culture and in xenografted nude mice. Moreover, overexpression of SPRY4-IT1 was found to have a key role in the epithelial-mesenchymal transition through the regulation of E-cadherin and vimentin expression. In EZH2-knockdown cells, which characteristically showed impaired cell proliferation and metastasis, the induction of SPRY4-IT1 depletion partially rescued the oncogenic phenotype, suggesting that SPRY4-IT1 repression has an important role in EZH2 oncogenesis. Of most relevance, translation of these findings into human NSCLC tissue samples demonstrated that patients with low levels of SPRY4-IT1 expression had a shorter overall survival time, suggesting that SPRY4-IT1 could be a biomarker for poor prognosis of NSCLC.
Phosphocreatine (PCr) plays a vital role in neuron and myocyte energy homeostasis. Currently, there are no routine diagnostic tests to noninvasively map PCr distribution with clinically relevant ...spatial resolution and scan time. Here, we demonstrate that artificial neural network-based chemical exchange saturation transfer (ANNCEST) can be used to rapidly quantify PCr concentration with robust immunity to commonly seen MRI interferences. High-quality PCr mapping of human skeletal muscle, as well as the information of exchange rate, magnetic field and radio-frequency transmission inhomogeneities, can be obtained within 1.5 min on a 3 T standard MRI scanner using ANNCEST. For further validation, we apply ANNCEST to measure the PCr concentrations in exercised skeletal muscle. The ANNCEST outcomes strongly correlate with those from
P magnetic resonance spectroscopy (R = 0.813, p < 0.001, t test). These results suggest that ANNCEST has potential as a cost-effective and widely available method for measuring PCr and diagnosing related diseases.
Benzene-1,3,5-tricarboxamide (BTA) glyco-monomers containing one, two or three mannose units are synthesized and formulated into differently patterned supramolecular glycopolymers through ...homo-assembly or co-assembly with non-functionalized BTAs. Unfortunately, no cellular activity could be detected. Excitingly, these glyco-BTA monomers could be formulated into hydrogels, paving the way for (immune) cell culture.
Mannose patterning is introduced into benzene-1,3,5-tricarboxamide (BTA)-based supramolecular assemblies through copolymerization of fully mannosylated
M3 BTA
with non-functionalized
nBTA
, and compared to their asymmetric homopolymer counterparts (
M1
and
M2 BTA
).
MicroRNAs (miRNAs) control gene expression through both translational repression and degradation of target messenger RNAs (mRNAs). However, the interplay between these processes and the precise ...molecular mechanisms involved remain unclear. Here, we show that translational inhibition is the primary event required for mRNA degradation. Translational inhibition depends on miRNAs impairing the function of the elF4F initiation complex. We define the RNA helicase elF4A2 as the key factor of elF4F through which miRNAs function. We uncover a correlation between the presence of miRNA target sites in the 3’ untranslated region (3’UTR) of mRNAs and secondary structure in the 5’UTR and show that mRNAs with unstructured 5’UTRs are refractory to miRNA repression. These data support a linear model for miRNA-mediated gene regulation in which translational repression via elF4A2 is required first, followed by mRNA destabilization.
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