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Examines the direct electromagnetic enhancement in surface enhanced Raman scattering on random self-affine fractal metal structures. Details on scattered electromagnetic intensity; Electromagnetic mechanism on silver, gold and copper substrates; Assessment of wavelength for the three metals.

Abstract: We study theoretically the surface plasmon electromagnetic field in the plane of the interface along which it propagates. Arbitrary surface plasmon fields are expressed by a linear superposition of elementary surface plasmon modes, thus obtaining an expression for the in-plane components similar to the angular spectrum model, which establishes the formal foundations of a two-dimensional surface plasmon optics. From this representation, we obtain the general description for surface plasmon modes be having as in-plane diffraction free beams. These new modes with their corresponding phase parameters are used to study surface plasmon self-imaging phenomenon and the synthesis of surface plasmon singularity regions (caustics) of surface plasmon fields, proposing experimental means to observe both. [Copyright &y& Elsevier]

A letter to the editor in response to the article "Making psychotherapy for borderline personality disorder accessible," by J. Paris, published in a previous issue is presented.

Museums usually look for new educational tools to enhance their exhibition. The Oteiza's museum in Navarre (Spain) especially gives importance to the dissemination of Jorge Oteiza's work to children at schools. Consequently, a didactics section was created with the objective of developing activities and relationship with schools. Jorge Oteiza represents one of the most important artists in the Spanish modern art and his sculptures stem from his proper philosophical concepts such as negative aesthetics via addition and subtraction, or activation of space and time. Such notions make the learning process at school complex. Thus, this study proposes a framework that aims to enhance the visit to the museum through a series of mini-games that shed light on these abstract concepts. Representative sculptures were selected and the corresponding activities were designed and developed in collaboration with the didactics section of the museum following a Co-Design approach. Then, the framework was tested by pupils from primary and secondary schools and students from educational practice. Therefore this paper provides a guideline to design educational games in collaboration with a museum, shows that mini educational games help students in learning artistic concepts and that motion-based touchless interfaces are not really adapted for classroom use. [ABSTRACT FROM AUTHOR]

Electromagnetic field confinement on sub‐wavelength scales is possible at the expense of increasing optical losses. Examples are surface plasmon polaritons and resonant structures, which suffer from absorption losses and radiative outcoupling, respectively. Here, the first experimental evidence of strong electromagnetic field confinement along the lateral (out‐of‐plane) direction in a near lossless metasurface that supports a symmetry‐protected Bound State in the Continuum is shown, which fully suppresses the radiative losses of resonant scatterers. This experimental demonstration, supported by coupled dipole calculations, is measured by a double near‐field probe technique to locally excite and detect the time evolution and confinement of the electric field onto the surface, achieving an amplitude decay length from the metasurface of λ/38 at 0.39 THz. [ABSTRACT FROM AUTHOR]

• Rare form of laser induced periodic surface structures observed on silicon. • Visualization of ripple formation process based on self-organization of nanoparticles. • Ripple periods as short as 160 nm. • Experimental setup to generate linear polarized laser pulses in the deep UV (193 nm). • Roughness-mediated plasmonic model describes the period evolution with angle of laser incidence. • Border region shows a pronounced photoluminescence emission in the visible. We have investigated the formation of laser-induced periodic surface structures (LIPSS or "ripples") on silicon upon excitation with p-polarized excimer laser pulses in the deep ultraviolet region (λ = 193 nm, 20 ns). Well-pronounced ripples with a period close to the laser wavelength were observed for pulse numbers N ≥ 100, and the ripple period increased with the angle of incidence. While these results seem to be qualitatively consistent with the standard Sipe-theory, we observed a fundamentally different ripple formation mechanism and ripple morphology. At low pulse numbers, isolated nanoparticles with a size of a few tens of nanometers are observed at the silicon surface, which then start to agglomerate in 2D and self-organize to form ripples with a very shallow modulation depth as the pulse number increases. Employing a recently developed plasmonic model based on the propagation of a surface plasmon polariton on a rough surface, we demonstrate excellent quantitative agreement of the evolution of the ripple period with incidence angle. Finally, we show that surface regions exposed to lower laser fluence feature micro- and nanopores, which give rise to pronounced photoluminescence (PL) emission in the visible spectral region, as opposed to the nanoparticle-based ripples not showing PL. [ABSTRACT FROM AUTHOR]

Looking forward includes looking back every now and then. In 2007, David Weller looked back at 30 years of biocontrol of soil-borne pathogens by Pseudomonas and signified that the progress made over decades of research has provided a firm foundation to formulate current and future research questions. It has been recognized for more than a century that soil-borne microbes play a significant role in plant growth and health. The recent application of high-throughput omics technologies has enabled detailed dissection of the microbial players and molecular mechanisms involved in the complex interactions in plant-associated microbiomes. Here, we highlight old and emerging plant microbiome concepts related to plant disease control, and address perspectives that modern and emerging microbiomics technologies can bring to functionally characterize and exploit plant-associated microbiomes for the benefit of plant health in future microbiome-assisted agriculture. It has been recognized for more than 100 years that soil-borne microbes play a significant role in plant growth and health. We highlight long standing and emerging concepts in plant microbe interactions in the rhizosphere in perspective of developing microbiome-assisted agriculture. [ABSTRACT FROM AUTHOR]

In this study, we assessed the psychometric properties of the Spanish Patient-Reported Outcomes Measurement Information System (PROMIS) Depression in an adult population-representative sample from Spain (n = 1,503). We tested unidimensionality and local independence item response theory (IRT) assumptions with confirmatory factor and bifactor models under the exploratory structural equations modeling framework. We evaluated item monotonicity assumption with Mokken scaling analysis. We calibrated the items with an IRT-graded response model and assessed score reliability and test information, and evidence of validity with regard to scores on external measures. To examine differential item functioning by age, sex, education, and country (United States vs. Spain, N = 2,271), we used ordinal logistic regression. Results support compliance with IRT assumptions. We found few signs of differential item functioning: Only one item showed country differential functioning between the United States (n = 768) and Spain, with minimal impact on the overall score. Information values were equivalent to reliabilities over 0.90 from -1 (low depression) to +4 SD (high depression) around the population score mean. Evidence of validity in relation to concurrent measures was supported by the expected correlation pattern with external variables of depression, but higher than expected correlations with anxiety were found. Results indicate that the Spanish version of PROMIS Depression is adequate for assessing and monitoring depression levels in the general population and that PROMIS Depression is especially suitable for cross-national comparisons. (PsycINFO Database Record (c) 2019 APA, all rights reserved). [ABSTRACT FROM AUTHOR]

The plasmonic origin of surface-enhanced Raman scattering (SERS) leads to the concept of hotspots and plasmon coupling that can be realized in the interstitial regions, or on specially engineered, silver and gold nanostructures. It is also possible to achieve spatial locations of high local field or hotspots on silver-island films (SIF) allowing single-molecule detection (SMD). When a single monomolecular layer coating the SIFs contains dye molecules dispersed in it, single-molecule impurities, (with an average of one hundred dye molecules in 1 µm2, which is the field of view of the micro-Raman system), SMD is observed as a rare statistical event. Here, the SMD results for silver-island films are presented, with the same nominal mass thickness, but differing in the localized surface plasmon resonance that is a function of the temperature of substrate during deposition. A blue-shifted plasmon can be seen as a decrease in plasmon coupling for deposition at higher temperature. A simple two-particle model for localized plasmon resonance coupling calculations, including the shape and substrate effects seems to explain the trend of observations. [ABSTRACT FROM AUTHOR]

The controlled tuning of interparticle distance at the nanoscale level is a major challenge for nanofabrication of surface-enhanced Raman scattering (SERS) active clusters and their application to molecular sensing. In fact, the geometrical properties of the narrow gaps between nanoparticles play a key role in determining the local field enhancement (and therefore, the SERS enhancement factor) and the spatial enhancement distribution in the gap region. Besides, very short interparticle distances may block the access of the analyte to the hot zone. In this paper, we report the synthesis of silver colloid NP clusters with interparticle distances fine tuned in the ≤2 nm range, by exploiting the chemical properties of linear α,ω-aliphatic diamines as molecular linkers with varying chain length. The bifunctional diamines also form intermolecular cavities within their self-assembled monolayers, suitable to host molecular analytes for nanosensing applications, as evidenced by SERS detection of organochlorine insecticides at the trace level. In this regard, the extension of the aliphatic chain played a crucial role in determining the SAM conformation and thus the final sensitivity of the functionalized SERS substrate. [ABSTRACT FROM AUTHOR]