Nonlinear gradient estimates for elliptic equations of general type

We study a very general model of nonvariational elliptic equations of p-Laplacian type. We prove the W ^1,q -estimates for each q > p regarding such a nonlinear elliptic equation in divergence form under the assumption that for each point and for each sufficiently small scale the nonlinearity is suitably close to a vector of the gradient in BMO space. In the same spirit our results can be easily extended to Orlicz spaces as well.     

High-performance polymer electrolyte membranes incorporated with 2D silica nanosheets in high-temperature proton exchange membrane fuel cells

Silica nanosheets(SN)derived from natural vermiculite(Verm)were successfully incorporated into polyethersulfone-polyvinylpyrrolidone(PES-PVP)polymer to fabricate high-temperature proton exchange membranes(HT-PEMs).The content of SN filler was varied(0.1-0.75 wt%)to study its influence on proton conductivity,power density and durability.Benefiting from the hydroxyl groups of SN that enable the formation of additional proton-transferring pathways,the inorganic-organic membrane displayed enhanced proton conductivity of 48.2 mS/cm and power density of 495 mW/cm² at 150℃ without humidification when the content of SN is 0.25 wt%.Furthermore,exfoliated SN(E-SN)and sulfonated SN(S-SN),which were fabricated by a liquid-phase exfoliation method and silane condensation,respectively,were embedded in PES-PVP polymer matrix by a simple blending method.Due to the significant contribution from sulfonic groups in S-SN,the membrane with 0.25 wt%S-SN reached the highest proton conductivity of51.5 mS/cm and peak power density of 546 mW/cm² at150℃,48%higher than the pristine PES-PVP membranes.Compared to unaltered PES-PVP membrane,SN added hybrid composite membrane demonstrated excellent durability for the fuel cell at 150℃.Using a facile method to prepare 2D SN from natural clay minerals,the strategy of exfoliation and functionalization of SN can be potentially used in the production of HT-PEMs.     

Phase behaviour for the (carbon dioxide + 2-phenoxyethyl acrylate) and (carbon dioxide + 2-phenoxyethyl methacrylate) systems at temperatures from (313.2 to 393.2) K and pressures from (5 to 31) MPa

The solubility curves for the (carbon dioxide + 2-phenoxyethyl acrylate) and (carbon dioxide + 2-phenoxyethyl methacrylate) systems were determined by a static view cell apparatus at five temperatures (313.2, 333.2, 353.2, 373.2, and 393.2) K as well as pressures up to 31.43 MPa. Two {carbon dioxide + (meth)acrylate} systems had continuous critical mixture curves with maxima in pressure located between the critical temperatures of carbon dioxide and 2-phenoxyethyl (meth)acrylate. The solubility of 2-phenoxyethyl (meth)acrylate in the {carbon dioxide + 2-phenoxyethyl (meth)acrylate} systems increases as the temperature increases at a fixed pressure. The (carbon dioxide + 2-phenoxyethyl acrylate) and (carbon dioxide + 2-phenoxyethyl methacrylate) systems exhibit type-I phase behaviour. The experimental results for the (carbon dioxide + 2-phenoxyethyl acrylate) and (carbon dioxide + 2-phenoxyethyl methacrylate) systems correlate with the Peng–Robinson equation of state using a van der Waals one-fluid mixing rule including two adjustable parameters. The critical properties of 2-phenoxyethyl acrylate and 2-phenoxyethyl methacrylate were predicted with the Joback and Lee–Kesler method.     

A dynamic surface prepared by electrochemical triggering of substituted methoxyphenol-terminated self-assembled monolayers for multi-functional purposes

We devised a methoxyphenol thiol derivative with an electron-withdrawing (–CHO) and an electron-donating (–CH₂OH) substituent for the preparation of a dynamic surface that can be used for multi-functional purposes. This molecule was electrochemically activated to an o-quinone form by the oxidative triggering through demethoxylation, followed by hydroxylation on para position upon potential cycling whose rate depended on the nature of substituents. An electron-withdrawing substituent facilitated nucleophilic addition of water, forming a 1,2,5-trihydroxy form, and only para-hydroquinone underwent a redox reaction. An electron-donating substituent, however, was not able to activate this process, leaving behind only an ortho form. The o-quinone showed catalytic activity toward ascorbic acid and NADH oxidation.     

Assessment of density functionals with long‐range and/or empirical dispersion corrections for conformational energy calculations of peptides

Density functionals with long‐range and/or empirical dispersion corrections, including LC‐ωPBE, B97‐D, ωB97X‐D, M06‐2X, B2PLYP‐D, and mPW2PLYP‐D functionals, are assessed for their ability to describe the conformational preferences of Ac‐Ala‐NHMe (the alanine dipeptide) and Ac‐Pro‐NHMe (the proline dipeptide) in the gas phase and in water, which have been used as prototypes for amino acid residues of peptides. For both dipeptides, the mean absolute deviation (MAD) is estimated to be 0.22–0.40 kcal/mol in conformational energy and 2.0–3.2° in torsion angles ? and ψ using these functionals with the 6‐311++G(d,p) basis set against the reference values calculated at the MP2/aug‐cc‐pVTZ//MP2/aug‐cc‐pVDZ level of theory in the gas phase. The overall performance is obtained in the order B2PLYP‐D ≈ mPW2PLYP‐D > ωB97X‐D ≈ M06‐2X > MP2 > LC‐ωPBE > B3LYP with the 6–311++G(d,p) basis set. The SMD model at the M06‐2X/6‐31+G(d) level of theory well reproduced experimental hydration free energies of the model compounds for backbone and side chains of peptides with MADs of 0.47 and 4.3 kcal/mol for 20 neutral and 5 charged molecules, respectively. The B2PLYP‐D/6‐311++G(d,p)//SMD M06‐2X/6‐31+G(d) level of theory provides the populations of backbone and/or prolyl peptide bond for the alanine and proline dipeptides in water that are consistent with the observed values. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

Interaction between the mouse homologue of CD99 and its ligand PILR as a mechanism of T cell receptor-independent thymocyte apoptosis

Here, we show that the interaction between two membrane proteins, the mouse homologue of CD99 (designated D4) and its ligand, paired immunoglobulin-like type 2 receptor (PILR), is one of the major mechanisms of thymocyte apoptosis. Using the polymeric fusion protein of PILR and IgG1 (PILR-Ig), we demonstrated that D4 ligation in the absence of T cell receptor (TCR) engagement leads to the induction of apoptosis, mainly at the double-positive stage of thymocytes. This was further confirmed by a blocking study in which blocking the interaction between D4 and PILR by soluble D4 protein led to reduced apoptosis in the fetal thymic organ culture with wild type and TCRα^-/- mice. Furthermore, the dissection of intracellular signaling pathway demonstrated that D4 cross-linking led to caspase activation without any change in mitochondrial membrane potential. Based on these data, we propose a mechanism for thymocyte depletion in which the interaction between D4 and PILR delivers an active signal.     

Output power improvement in an Yb-doped fiber laser with an additional unpumped Yb-doped fiber

Master oscillator power amplifier (MOPA) technology has been widely used in high-power or ultrashort-pulse fiber laser systems because the shape of the laser pulse can be easily adjusted. Usually, the first amplification stage of a 1064 nm fiber laser uses the core-pumped Yb-doped fiber amplifier (YDFA); however, the gain or output power is limited owing to the strong amplifier spontaneous emission (ASE) in the 1030 nm band. This paper presents the improved output power in an YDFA by inserting an additional unpumped Yb-doped fiber, which absorbs the lost backward ASE emitted from the pump end. We achieved an output power increase of more than 10% in a low-power signal, and the increase in output power decreased as the signal power increased. Moreover, the insertion of an additional unpumped Yb-doped fiber restricted the unwanted 1030 nm lasing in a low-power signal.