Palladium catalyzed coupling reactions have emerged as a versatile, convenient, selective and mild protocol that can usually be adapted in any synthetic scheme for important target molecules with ...various degrees of structural complexity. While anchored catalysts offer recycling advantages, palladium nanoparticles display an impressive ability to catalyse coupling reactions. Along with their successful applications in organic synthesis, controversy has also arisen concerning the exact nature - heterogeneous or homogeneous - of the reaction catalyzed by palladium nanoparticles.
Palladium catalyzed coupling reactions have emerged as a versatile, convenient, selective and mild protocol that can usually be adapted in any synthetic scheme for important target molecules with various degrees of structural complexity.
Water is the universal solvent and plays a critical role in all known geological and biological processes. Confining water in nano-scale domains, as encountered in sedimentary rocks, in biological, ...and in engineered systems, leads to the deviations in water's physicochemical properties relative to those measured for the non-confined phase. In our comprehensive analysis, we demonstrate that nano-scale confinement leads to the decrease in the melting/freezing point temperature, density, and surface tension of confined water. With increasing degree of spatial confinement the population of networked water, as evidenced by alterations in the O-H stretching modes, increases. These analyses were performed on two groups of mesoporous silica materials, which allows to separate pore size effects from surface chemistry effects. The observed systematic effects of nano-scale confinement on the physical properties of water are driven by alterations to water's hydrogen-bonding network-influenced by water interactions with the silica surface - and has implications for how we understand the chemical and physical properties of liquids confined in porous materials.
Abstract
Van der Waals materials and heterostructures that manifest strongly bound exciton states at room temperature also exhibit emergent physical phenomena and are of great promise for ...optoelectronic applications. Here, we demonstrate that nanostructured, multilayer transition metal dichalcogenides (TMDCs) by themselves provide an ideal platform for excitation and control of excitonic modes, paving the way to exciton-photonics. Hence, we show that by patterning the TMDCs into nanoresonators, strong dispersion and avoided crossing of exciton, cavity photons and plasmon polaritons with effective separation energy exceeding 410 meV can be controlled with great precision. We further observe that inherently strong TMDC exciton absorption resonances may be completely suppressed due to excitation of hybrid light-matter states and their interference. Our work paves the way to the next generation of integrated exciton optoelectronic nano-devices and applications in light generation, computing, and sensing.
Plasmon-resonant nanoparticle complexes show highly promising potential for light-triggered, remote-controlled delivery of oligonucleotides on demand, for research and therapeutic purposes. Here we ...investigate the light-triggered release of DNA from two types of nanoparticle substrates: Au nanoshells and Au nanorods. Both light-triggered and thermally induced release are distinctly observable from nanoshell-based complexes, with light-triggered release occurring at an ambient solution temperature well below the DNA melting temperature. Surprisingly, no analogous measurable release was observable from nanorod-based complexes below the DNA melting temperature. These results suggest that a nonthermal mechanism may play a role in plasmon resonant, light-triggered DNA release.
Plasmonic absorption of light can lead to significant local heating in metallic nanostructures, an effect that defines the subfield of thermoplasmonics and has been leveraged in diverse applications ...from biomedical technology to optoelectronics. Quantitatively characterizing the resulting local temperature increase can be very challenging in isolated nanostructures. By measuring the optically induced change in resistance of metal nanowires with a transverse plasmon mode, we quantitatively determine the temperature increase in single nanostructures with the dependence on incident polarization clearly revealing the plasmonic heating mechanism. Computational modeling explains the resonant and nonresonant contributions to the optical heating and the dominant pathways for thermal transport. These results, obtained by combining electronic and optical measurements, place a bound on the role of optical heating in prior experiments and suggest design guidelines for engineered structures meant to leverage such effects.
Au nanoparticles with plasmon resonances in the near-infrared (NIR) region of the spectrum efficiently convert light into heat, a property useful for the photothermal ablation of cancerous tumors ...subsequent to nanoparticle uptake at the tumor site. A critical aspect of this process is nanoparticle size, which influences both tumor uptake and photothermal efficiency. Here, we report a direct comparative study of ∼90 nm diameter Au nanomatryoshkas (Au/SiO2/Au) and ∼150 nm diameter Au nanoshells for photothermal therapeutic efficacy in highly aggressive triple negative breast cancer (TNBC) tumors in mice. Au nanomatryoshkas are strong light absorbers with 77% absorption efficiency, while the nanoshells are weaker absorbers with only 15% absorption efficiency. After an intravenous injection of Au nanomatryoshkas followed by a single NIR laser dose of 2 W/cm2 for 5 min, 83% of the TNBC tumor-bearing mice appeared healthy and tumor free >60 days later, while only 33% of mice treated with nanoshells survived the same period. The smaller size and larger absorption cross section of Au nanomatryoshkas combine to make this nanoparticle more effective than Au nanoshells for photothermal cancer therapy.
Observed changes in intense precipitation (e.g., the frequency of very heavy precipitation or the upper 0.3% of daily precipitation events) have been analyzed for over half of the land area of the ...globe. These changes have been linked to changes in intense precipitation for three transient climate model simulations, all with greenhouse gas concentrations increasing during the twentieth and twenty-first centuries and doubling in the later part of the twenty-first century. It was found that both the empirical evidence from the period of instrumental observations and model projections of a greenhouse-enriched atmosphere indicate an increasing probability of intense precipitation events for many extratropical regions including the United States. Although there can be ambiguity as to the impact of more frequent heavy precipitation events, the thresholds of the definitions of these events were raised here, such that they are likely to be disruptive. Unfortunately, reliable assertions of very heavy and extreme precipitation changes are possible only for regions with dense networks due to the small radius of correlation for many intense precipitation events.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, and perturbative triples CCSD(T) ...reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green’s function (scGW 0), non-self-consistent G 0 W 0 based on several mean-field starting points, and a “beyond GW” second-order screened exchange (SOSEX) correction to G 0 W 0. We also describe the implementation of the self-consistent Coulomb hole with screened exchange method (COHSEX), which serves as one of the mean-field starting points. The best performers overall are G 0 W 0+SOSEX and G 0 W 0 based on an IP-tuned long-range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments.
This article analyses the nexus between the Caribbean's manifold vulnerabilities and the direct and structural violence evident throughout the region's history. It argues that Caribbean states are ...threatened not only by direct violence but also by the structural violence permeating in impoverished and marginalised sectors of the state-society complex. Both forms of violence are attributable to the historical legacy of colonisation, to US paternalism and hegemonic dominance in the post-colonial era, and to the persistence of the coloniality of power, even after Caribbean states won their independence from European imperial powers. Today, the region is, per capita, one of the most violent areas on the globe. Evidence of concatenated violence is growing across this region, demonstrating the difficulty small underdeveloped states have in addressing threats to their security, independence, economic viability, and continued existence in the intermestic environment within which they operate.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
There is a crisis of global governance at this moment in our history -- a moment being labeled as 'the interregnum -- a moment of transition from one world order to another. The turbulence and ...disequilibrium of this moment in our history have triggered intense and growing interest in the concept and practice of governance at all levels. This is not a reflexive moment; it is a time for serious reflection and contemplation; a time for reconceptualizing ‘global governance’; an auspicious moment for constructing a new global governance paradigm. To assist in this introspective exercise, it may be important to shift from 'problem-solving' theorizing to a 'critical theory' approach that stands outside prevailing understandings of what global governance has come to mean and discard the oversimplified state-centric vision of world order; replacing it with the more nuanced 'summative' global governance - a concept that is more sophisticated and flexible than previous ones and may provide the needed space and time for us to transform the practice of global governance.
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