Pressure-Dependent Kinetics of the Reaction between CH₃OO and OH Focusing on the Product Yield of Methyltrioxide (CH₃OOOH)

The reaction kinetics of methyl peroxy radical (CH3OO) and hydroxyl radical (OH) has attracted an increasing level of interest in the past decade, while the branching yields of various product channels are still under debate. In this work, a comprehensive theoretical effort was made to investigate the branching yield of the stabilized methyltrioxide (CH3OOOH, TRIOX) adduct, which has recently been a research focus. Our computed branching ratio of TRIOX at 298 K and 760 Torr is ∼0.04, in agreement with the result of multiplexed photoionization mass spectrometry. We show that the large branching yield obtained in an early theoretical study mainly originated from the collision-induced strong stabilization presented in their simulation. Our findings clarify the controversial product yield results for this important species in recent studies. The computed rate constants over wide temperature and pressure ranges allow better integration of this reaction into global atmospheric models and low-temperature combustion kinetic models

How Firms Innovate: R&D, Non-R&D, and Technology Adoption

Non-R&D innovation is a common economic phenomenon, though R&D has been the central focus of policy making and scholarly research in the field of innovation. An analysis of the third European Community Innovation Survey (CIS-3) results for 15 countries finds that almost half of innovative European firms did not perform R&D in-house. Firms with weak in-house innovative capabilities and which source information from suppliers and competitors tend to innovate through non-R&D activities. In contrast, firms that engage in product innovation, find clients, universities and research institutions an important information source for innovation, or apply for patents or use other appropriation methods are more likely to perform R&D. However, non-R&D performers do not form a consistent block, with several notable differences between firms that use three different methods of innovating without performing R&D. Many of these determinants also influence the share of total innovation expenditures that are spent on non-R&D innovation activities. Furthermore, an analysis of the determinants of the share of each firm's total innovation expenditures for non-R&D activities shows that the factors that influence how innovation expenditures are distributed is generally consistent across sectors and European countries

Formation of Substituted Alkyls as Precursors of Peroxy Radicals with a Rapid H‑Shift in the Atmosphere

Long straight-chain alkyl peroxy (ROO) radicals substituted with CC and oxo functional groups are expected to undergo a rapid hydrogen shift (H-shift), which is a critical step in the atmospheric autoxidation mechanism. The existence of a weak tertiary C–H bond plays a key role in the rapid H-shift. Here, the reaction kinetics between OH and two typical long straight-chain functionalized volatile organic compounds, 3-methyl-1-hexene (3-MH) and 2-methylpentanal (2-MP), was theoretically investigated to reveal the fate of the weak C–H bond. The results indicate that the most favored reaction pathways are direct consumption (H-abstraction of 2-MP) and indirect destruction (addition of OH to 3-MH) of the “weak” tertiary C–H bond. The yields of abstraction pathways producing precursors of ROO radicals that undergo rapid H-shifts are computed to be less than 10% for both 3-MH + OH and 2-MP + OH reactions

Table_1_The Role of the Two-Component System PhoP/PhoQ in Intrinsic Resistance of Yersinia enterocolitica to Polymyxin.DOCX

Polymyxin is the “last resort” of antibiotics. The self-induced resistance to polymyxin in Gram-negative bacteria could be mediated by lipopolysaccharide (LPS) modification, which is regulated by the two-component system, PhoP/PhoQ. Yersinia enterocolitica is a common foodborne pathogen. However, PhoP/PhoQ has not been thoroughly studied in Y. enterocolitica. In this study, the functions of PhoP/PhoQ in Y. enterocolitica intrinsic resistance were investigated. The resistance of Y. enterocolitica was found to decrease with the deletion of PhoP/PhoQ. Further, PhoP/PhoQ was found to play an important role in maintaining membrane permeability, intercellular metabolism, and reducing membrane depolarization. Based on subsequent studies, the binding ability of polymyxin to Y. enterocolitica was decreased by the modification of LPS with structures, such as L-Ara4N and palmitate. Analysis of the gene transcription levels revealed that the LPS modification genes, pagP and arn operon, were downregulated with the deletion of PhoP/PhoQ in Y. enterocolitica during exposure to polymyxin. In addition, pmrA, pmrB, and eptA were downregulated in the mutants compared with the wild-type strain. Such findings demonstrate that PhoP/PhoQ contributes to the intrinsic resistance of Y. enterocolitica toward polymyxins. LPS modification with L-Ara4N or palmitate is mainly responsible for the resistance of Y. enterocolitica to polymyxins. The transcription of genes related to LPS modification and PmrA/PmrB can be both affected by PhoP/PhoQ in Y. enterocolitica. This study adds to current knowledge regarding the role of PhoP/PhoQ in intrinsic resistance of Y. enterocolitica to polymyxin.</p

High Energy Storage of PLZT/PVDF Nanocomposites with a Trilayered Structure

Designing a multilayer structure is an efficient strategy to synthesize dielectric nanocomposite films with excellent dielectric properties and energy density. In this study, lead lanthanum zirconate titanate (PLZT)/poly­(vinylidene fluoride) (PVDF) films with good dielectric properties and boron nitride nanosheet (BNNS)/PVDF films with high breakdown strength were prepared using the casting method. Then, a trilayer-structured film with a PLZT/PVDF layer sandwiched between two BNNS/PVDF layers was fabricated using the hot-pressing method. The effect of PLZT fillers with different dimensions on the electrical properties of the trilayer nanocomposites has been investigated. The results show that (BNNS/PVDF)–(PLZT/PVDF)–(BNNS/PVDF) nanocomposite films containing PLZT nanowires have excellent dielectric properties and energy density, with a dielectric constant of 10.34, a breakdown strength of 429.03 MV/m, and the maximum energy storage density nearly 5 J/cm3, far more than those of the biaxially oriented polypropylenes

Oriented Organic Nanowires Self-Assembled on a Graphene Surface

Molecular self-assembly of organic molecules on two-dimensional atomic crystals involves molecule–molecule interactions, molecule–surface interactions, or their combination. Most previous studies are focused on self-assembled organic monolayers. Here, for the first time, we report oriented organic nanowires self-assembled on a graphene surface in the atmosphere. Oriented lauroyl peroxide nanowires were formed when cooling down the melting lauroyl peroxide layer on a graphene surface but were not formed on SiO₂ and copper surfaces. Structural analysis and theoretical simulation revealed that the combination of strong molecule–molecule packing interactions, weak molecule–molecule linking interactions, and weak molecule–surface interactions contributed to the formation of nanowires, while the orientation of nanowires depended on the six-fold rotational symmetry of graphene and strong molecule–surface interactions

Table_1_Osmoregulated Periplasmic Glucans Transmit External Signals Through Rcs Phosphorelay Pathway in Yersinia enterocolitica.DOCX

Fast response to environmental changes plays a key role in the transmission and pathogenesis of Yersinia enterocolitica. Osmoregulated periplasmic glucans (OPGs) are known to be involved in environmental perception of several Enterobacteriaceae pathogens; however, the biological function of OPGs in Y. enterocolitica is still unclear. In this study, we investigated the role of OPGs in Y. enterocolitica by deleting the opgGH operon encoding enzymes responsible for OPGs biosynthesis. Complete loss of OPGs in the ΔopgGH mutant resulted in decreased motility, c-di-GMP production, biofilm formation and smaller cell size, whereas the overproduction of OPGs through restoration of opgGH expression promoted c-di-GMP/biofilm production and increased antibiotic resistance of Y. enterocolitica. Gene expression analysis revealed that opgGH deletion reduced transcription of flhDC, ftsAZ, hmsT and hmsHFRS genes regulated by the Rcs phosphorelay system, whereas additional deletion of rcs family genes (rcsF, rcsC, or rcsB) reversed this effect and restored motility and c-di-GMP/biofilm production but further reduced cell size. Furthermore, disruption of the Rcs phosphorelay increased the motility and promoted the induction of biofilm and c-di-GMP production regulated by OPGs through upregulating the expression of flhDC, hmsHFRS, and hmsT. However, deletion of genes encoding the EnvZ/OmpR phosphorelay downregulated the flhDC, hmsHFRS and hmsT expression, leading to the decreased motility and prevented the induction of biofilm and c-di-GMP production regulated by OPGs. These results indicated that Rcs phosphorelay had the effect on OPGs-mediated functional responses in Y. enterocolitica. Our findings disclose part of the biological role of OPGs and the underlying molecular mechanisms associated with Rcs system in the regulation of the pathogenic phenotype in Y. enterocolitica.</p

Influence of Oxygen Atoms and Ring Strain on the Low-Temperature Oxidation Pathways of 1,3-Dioxolane

Biohybrid fuels are a promising solution for making the transportation sector more environmentally friendly. One such interesting fuel candidate is 1,3-dioxolane, which can be produced from inedible biomass. However, very little kinetics data are available for the low-temperature oxidation of this fuel molecule. To remedy this, we present the reaction kinetics of O2 addition to 1,3-dioxolanyl radicals in this work. All energies have been calculated at the DLPNO-CCSD(T)/CBS//B2PLYPD3BJ/6-311+g(d,p) level of theory. Temperature- and pressure-dependent reaction rate constants have been calculated with the RRKM/master equation method. The effects of heterocyclic oxygen atoms and ring strain on the low-temperature oxidation of 1,3-dioxolane are also compared to that of similar fuel molecules containing five heavy atoms: cyclopentane, tetrahydrofuran, and diethyl ether (DEE). The ring-opening β-scission reactions of the dioxolane hydroperoxy species are found to be the most dominant pathways following the oxidation of 1,3-dioxolanyl radicals. The heterocyclic oxygen atoms in 1,3-dioxolane weaken its C–O bonds, which leads to low barrier heights of the ring-opening reactions. Ring strain in 1,3-dioxolane increases the barriers for isomerization reactions of peroxy radicals compared to the similar reactions of DEE, which has a chain structure

Fig 4 -

(A). Overall survival curve by TNM stage. TNM: tumor-node-metastasis. (B). Overall survival curve by recurrence state. RE: recurrence.</p

Flow diagram of the study population.

Flow diagram of the study population.</p