Chemical Protein Synthesis Enabled Mechanistic Studies on the Molecular Recognition of K27‐linked Ubiquitin Chains

New synthetic strategies that exploited the strengths of both chemoselective ligation and recombinant protein expression were developed to prepare K27 di‐ubiquitins (diUb), which enabled mechanistic studies on the molecular recognition of K27‐linked Ubs by single‐molecule Förster resonance energy transfer (smFRET) and X‐ray crystallography. The results revealed that free K27 diUb adopted a compact conformation, whereas upon binding to UCHL3, K27 diUb was remodeled to an open conformation. The K27 isopeptide bond remained rigidly buried inside the diUb moiety during binding, an interesting unique structural feature that may explain the distinctive biological function of K27 Ub chains.     

2-IPMA Ameliorates PM2.5-Induced Inflammation by Promoting Primary Ciliogenesis in RPE Cells

Primary cilia mediate the interactions between cells and external stresses. Thus, dysregulation of primary cilia is implicated in various ciliopathies, e.g., degeneration of the retina caused by dysregulation of the photoreceptor primary cilium. Particulate matter (PM) can cause epithelium injury and endothelial dysfunction by increasing oxidative stress and inflammatory responses. Previously, we showed that PM disrupts the formation of primary cilia in retinal pigment epithelium (RPE) cells. In the present study, we identified 2-isopropylmalic acid (2-IPMA) as a novel inducer of primary ciliogenesis from a metabolite library screening. Both ciliated cells and primary cilium length were increased in 2-IPMA-treated RPE cells. Notably, 2-IPMA strongly promoted primary ciliogenesis and restored PM2.5-induced dysgenesis of primary cilia in RPE cells. Both excessive reactive oxygen species (ROS) generation and activation of a stress kinase, JNK, by PM2.5 were reduced by 2-IPMA. Moreover, 2-IPMA inhibited proinflammatory cytokine production, i.e., IL-6 and TNF-α, induced by PM2.5 in RPE cells. Taken together, our data suggest that 2-IPMA ameliorates PM2.5-induced inflammation by promoting primary ciliogenesis in RPE cells.     

Entropy-Energy Inequality for a Qutrit on the Example of a Three-Level Atom

Russian Physics Journal - We consider the entropy-energy inequality for a three-level atom implemented on superconducting circuits with the Josephson junction. It is suggested to use the positivity...     

An off-on fluorescence probe targeting mitochondria based on oxidation-reduction response for tumor cell and tissue imaging

In this study, a tumor-targeting poly(d, l-lactic-co-glycolic acid) (PLGA) loaded “off-on” fluorescent probe nanoparticle (PFN) delivery system was developed to evaluate the region of tumor by off-on fluorescence. The biodegradability of the nanosize PFN delivery system readily released the probe under tumor acidic conditions. The probe with good biocompatibility was used to monitor the intracellular glutathione (GSH) of cancer cells and selectively localize to mitochondria for tumor imaging. The incorporated tumor-targeting probe was based on the molecular photoinduced electron transfer (PET) mechanism preventing fluorescence (“off” state) and could be easily released under tumor acidic conditions. However, the released tumor-targeting fluorescence probe molecule was selective towards GSH with high selectivity and an ultra-sensitivity for the mitochondria of cancer cells and tissues significantly increasing the probe molecule fluorescence signal (“on” state). The tumor-targeting fluorescence probe showed sensitivity to GSH avoiding interference from cysteine and homocysteine. The PFNs could enable fluorescence-guided cancer imaging during cancer therapy. This work may expand the biological applications of PFNs as a diagnostic reagent, which will be beneficial for fundamental research in tumor imaging.

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Graphical abstract The tumor-bearing mice were injected intravenously through the tail with the PFNs; after injection, the PFNs can accumulate to tumor region via the EPR effect. The PFNs can prolong blood circulation time and easily degraded under tumor acidic conditions to release an off-on probe in tumor, and the probe can target glutathione of mitochondria, making probe fluorescence enhanced largely (“on” state).

     

Improving precursor adsorption characteristics in ATR-FTIR spectroscopy with a ZrO2 nanoparticle coating

Journal of Nanoparticle Research - Transparent superhydrophobic coatings, which are highly desired for the protection of material surfaces, have been limited to particular kinds of materials, e.g....     

Phase transition in anisotropic holographic superfluids with arbitrary dynamical critical exponent z and hyperscaling violation factor $$\alpha $$

Einstein-scalar-U(2) gauge field theory is considered in a spacetime characterized by \(\alpha \) and z, which are the hyperscaling violation factor and the dynamical critical exponent, respectively. We consider a dual fluid system of such a gravity theory characterized by temperature T and chemical potential \(\mu \). It turns out that there is a superfluid phase transition where a vector order parameter appears which breaks SO(3) global rotation symmetry of the dual fluid system when the chemical potential becomes a certain critical value. To study this system for arbitrary z and \(\alpha \), we first apply Sturm–Liouville theory and estimate the upper bounds of the critical values of the chemical potential. We also employ a numerical method in the ranges of \(1 \le z \le 4\) and \(0 \le \alpha \le 4\) to check if the Sturm–Liouville method correctly estimates the critical values of the chemical potential. It turns out that the two methods are agreed within 10 percent error ranges. Finally, we compute free energy density of the dual fluid by using its gravity dual and check if the system shows phase transition at the critical values of the chemical potential \(\mu _\mathrm{c}\) for the given parameter region of \(\alpha \) and z. Interestingly, it is observed that the anisotropic phase is more favored than the isotropic phase for relatively small values of z and \(\alpha \). However, for large values of z and \(\alpha \), the anisotropic phase is not favored.     

Characterization of wafer-scale MoS2 and WSe2 2D films by spectroscopic ellipsometry

Here, we present the spectroscopic ellipsometry investigation of synthetically grown wafer-scale two-dimensional (2D) MoS₂ and WSe₂ films to access quality and thickness uniformity. MoS₂ and WSe₂ samples were grown by chemical vapor deposition and atomic layer deposition, respectively. Complex dielectric function ($\epsilon ={\epsilon }_1+i{\epsilon }_2$) and thickness information of these 2D films were extracted from the measured data using multilayer optical calculations. Broad spectral range (1.2–6 eV) and multiple angles of incidence were used to reduce correlations among fitting parameter. Lineshape of ε of MoS₂ and WSe₂ monolayer films are consistent with literature but shows higher values, suggests better quality of our samples. Eight-inch wafer size MoS₂ monolayer sample shows ～ 70% uniformity with an average thickness of 0.65 ± 0.2 nm, and three-layer WSe₂ sample of 8 × 1 cm² area shows ～ 80% uniformity with an average thickness of 2.5 ± 0.4 nm. Our results will be helpful to accelerate commercialization process of 2D devices.     

Separability and Entanglement in the Hilbert Space Reference Frames Related Through the Generic Unitary Transform for Four Level System

Quantum correlations in the state of four-level atom are investigated by using generic unitary transforms of the classical (diagonal) density matrix. Partial cases of pure state, X-state, Werner state are studied in details. The geometrical meaning of unitary Hilbert reference-frame rotations generating entanglement in the initially separable state is discussed. Characteristics of the entanglement in terms of concurrence, entropy and negativity are obtained as functions of the unitary matrix rotating the reference frame.     

Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase

We produced controlled heliconical structures of a twist-bend nematic (N_TB) liquid-crystal (LC) phase in nanoconfinement in a porous anodic aluminium oxide (AAO) film. The structural parameters of the N_TB phase such as conical angle and helical pitch can be modulated by varying the surface energy of the inner surface of the porous AAO film, done by using different self-assembled monolayers (SAMs). The LC molecules tend to be more freely packed, thus forming a larger conical angle, when placed on the tri-deca-fluoro-1,1,2,2-tetrahydrooctyl-trichlorosilane (FOTS)-treated substrate, which has a relatively low surface energy. In contrast, the molecules form a more tightly packed structure, and thus a smaller conical angle, when placed on the 2-(methoxy(polyethyleneoxy)-propyl)trimethoxysilane (PEG 6/9)-treated substrate, which has higher surface energy. This work improves our collective understanding of self-assembled heliconical structures in the N_TB phase.     

Combustion of Inert-Gas-Diluted Volatile Organic Compounds Using a Fuel-Rich Pilot Flame and Rotating Arc Plasma

Plasma Chemistry and Plasma Processing - This report proposes a method that uses plasma in combination with combustion to remove very low concentrations of volatile organic compounds (VOCs) that...