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On‐surface synthesis has become a prominent method for growing low‐dimensional carbon‐based nanomaterials on metal surfaces. However, the necessity of decoupling organic nanostructures from metal substrates to exploit their properties requires either transfer methods or new strategies to perform reactions directly on inert surfaces. The use of on‐surface light‐induced reactions directly on semiconductor/insulating surfaces represents an alternative approach to address these challenges. Here, exploring the photochemical activity of different organic molecules on a SnSe semiconductor surface under ultra‐high vacuum, we present a novel on‐surface light‐induced reaction. The selective photodissociation of the anhydride group is observed, releasing CO and CO2. Moreover, we rationalize the relationship between the photochemical activity and the π‐conjugation of the molecular core. The different experimental behaviour of two model anhydrides was elucidated by theoretical calculations, showing how the molecular structure influences the distribution of the excited states. Our findings open new pathways for on‐surface synthesis directly on technologically relevant substrates. [ABSTRACT FROM AUTHOR]

On‐surface synthesis has become a prominent method for growing low‐dimensional carbon‐based nanomaterials on metal surfaces. However, the necessity of decoupling organic nanostructures from metal substrates to exploit their properties requires either transfer methods or new strategies to perform reactions directly on inert surfaces. The use of on‐surface light‐induced reactions directly on semiconductor/insulating surfaces represents an alternative approach to address these challenges. Here, exploring the photochemical activity of different organic molecules on a SnSe semiconductor surface under ultra‐high vacuum, we present a novel on‐surface light‐induced reaction. The selective photodissociation of the anhydride group is observed, releasing CO and CO2. Moreover, we rationalize the relationship between the photochemical activity and the π‐conjugation of the molecular core. The different experimental behaviour of two model anhydrides was elucidated by theoretical calculations, showing how the molecular structure influences the distribution of the excited states. Our findings open new pathways for on‐surface synthesis directly on technologically relevant substrates. [ABSTRACT FROM AUTHOR]

This letter introduces an unconditionally stable finite‐difference time‐domain (FDTD) method, based on the locally one‐dimensional (LOD) technique, for the solution of the two‐dimensional scalar wave equation (WE) in homogeneous media. The second spatial derivatives in the WE are discretized by using a three‐point compact (implicit) finite‐difference formula with a free parameter. This formula has second‐order accuracy and becomes fourth‐order by properly selecting the parameter value. Moreover, the resulting algorithm only involves tridiagonal matrices, as when using standard (explicit) second‐order finite differences. Additionally, a stability analysis is performed and the numerical dispersion relation of the method is derived. The proposed compact LOD‐WE‐FDTD technique has been applied to the calculation of resonant frequencies in a metallic ridge cavity. The accuracy of the results obtained has been studied as a function of the parameter value. [ABSTRACT FROM AUTHOR]

A unified view of direct-integration (DI) and exponential-time-differencing (ETD) methods to incorporate Drude media, such as isotropic plasma and microwave graphene, into finite-difference time-domain (FDTD) simulators is provided. To this end, the Drude constitutive relation is expressed in integral form and the DI integrators are obtained by applying quadrature rules. Analogously, the ETD integrators are obtained by starting from the variation of constants formula and applying the same quadrature rules as in the DI case. This approach allows one to directly compare the two families of methods. In addition, the accuracy of each integrator is discussed and the stability condition of the resulting FDTD schemes is derived in exact closed form by applying the von Neumann method. [ABSTRACT FROM AUTHOR]

On‐surface synthesis has recently emerged as a powerful strategy to design conjugated polymers previously precluded in conventional solution chemistry. Here, an N‐containing pentacene‐based precursor (tetraazapentacene) is ex‐professo synthesized endowed with terminal dibromomethylene (:CBr2) groups to steer homocoupling via dehalogenation on metallic supports. Combined scanning probe microscopy investigations complemented by theoretical calculations reveal how the substrate selection drives different reaction mechanisms. On Ag(111) the dissociation of bromine atoms at room temperature triggers the homocoupling of tetraazapentacene units together with the binding of silver adatoms to the nitrogen atoms of the monomers giving rise to a N‐containing conjugated coordination polymer (P1). Subsequently, P1 undergoes ladderization at 200 °C, affording a pyrrolopyrrole‐bridged conjugated polymer (P2). On Au(111) the formation of the intermediate polymer P1 is not observed and, instead, after annealing at 100 °C, the conjugated ladder polymer P2 is obtained, revealing the crucial role of metal adatoms on Ag(111) as compared to Au(111). Finally, on Ag(100) the loss of :CBr2 groups affords the formation of tetraazapentacene monomers, which coexist with polymer P1. Our results contribute to introduce protocols for the synthesis of N‐containing conjugated polymers, illustrating the selective role of the metallic support in the underlying reaction mechanisms. [ABSTRACT FROM AUTHOR]

We report on the synthesis and characterization of atomically precise one‐dimensional diradical peripentacene polymers on a Au(111) surface. By means of high‐resolution scanning probe microscopy complemented by theoretical simulations, we provide evidence of their magnetic properties, which arise from the presence of two unpaired spins at their termini. Additionally, we probe a transition of their magnetic properties related to the length of the polymer. Peripentacene dimers exhibit an antiferromagnetic (S=0) singlet ground state. They are characterized by singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 2.5 meV, whereas trimers and longer peripentacene polymers reveal a paramagnetic nature and feature Kondo fingerprints at each terminus due to the unpaired spin. Our work provides access to the precise fabrication of polymers featuring diradical character which are potentially useful in carbon‐based optoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

We report on the synthesis and characterization of atomically precise one‐dimensional diradical peripentacene polymers on a Au(111) surface. By means of high‐resolution scanning probe microscopy complemented by theoretical simulations, we provide evidence of their magnetic properties, which arise from the presence of two unpaired spins at their termini. Additionally, we probe a transition of their magnetic properties related to the length of the polymer. Peripentacene dimers exhibit an antiferromagnetic (S=0) singlet ground state. They are characterized by singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 2.5 meV, whereas trimers and longer peripentacene polymers reveal a paramagnetic nature and feature Kondo fingerprints at each terminus due to the unpaired spin. Our work provides access to the precise fabrication of polymers featuring diradical character which are potentially useful in carbon‐based optoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

The calculation of dispersion diagrams and field patterns of metallic rectangular waveguides filled with an inhomogeneous dielectric whose permittivity varies continuously along the broad size of the guide is considered. In general, this problem has no exact solution, thus numerical techniques should be used. In this article, the pseudospectral frequency‐domain (PSFD) method is proposed to address the problem. Starting from the Helmholtz equation, a matrix eigenvalue problem is obtained by applying the collocation technique with Chebyshev polynomials as basis functions. The results obtained are compared with those calculated by the conventional finite‐difference frequency‐domain method showing that the PSFD technique provides an excellent accuracy. [ABSTRACT FROM AUTHOR]

Engineering low‐band‐gap π‐conjugated polymers is a growing area in basic and applied research. The main synthetic challenge lies in the solubility of the starting materials, which precludes advancements in the field. Here, we report an on‐surface synthesis protocol to overcome such difficulties and produce poly(p‐anthracene ethynylene) molecular wires on Au(111). To this aim, a quinoid anthracene precursor with =CBr2 moieties is deposited and annealed to 400 K, resulting in anthracene‐based polymers. High‐resolution nc‐AFM measurements confirm the nature of the ethynylene‐bridge bond between the anthracene moieties. Theoretical simulations illustrate the mechanism of the chemical reaction, highlighting three major steps: dehalogenation, diffusion of surface‐stabilized carbenes, and homocoupling, which enables the formation of an ethynylene bridge. Our results introduce a novel chemical protocol to design π‐conjugated polymers based on oligoacene precursors and pave new avenues for advancing the emerging field of on‐surface synthesis. [ABSTRACT FROM AUTHOR]

Engineering low‐band‐gap π‐conjugated polymers is a growing area in basic and applied research. The main synthetic challenge lies in the solubility of the starting materials, which precludes advancements in the field. Here, we report an on‐surface synthesis protocol to overcome such difficulties and produce poly(p‐anthracene ethynylene) molecular wires on Au(111). To this aim, a quinoid anthracene precursor with =CBr2 moieties is deposited and annealed to 400 K, resulting in anthracene‐based polymers. High‐resolution nc‐AFM measurements confirm the nature of the ethynylene‐bridge bond between the anthracene moieties. Theoretical simulations illustrate the mechanism of the chemical reaction, highlighting three major steps: dehalogenation, diffusion of surface‐stabilized carbenes, and homocoupling, which enables the formation of an ethynylene bridge. Our results introduce a novel chemical protocol to design π‐conjugated polymers based on oligoacene precursors and pave new avenues for advancing the emerging field of on‐surface synthesis. [ABSTRACT FROM AUTHOR]

In recent years, split-step finite-difference time-domain (SS-FDTD) methods have attracted much attention and many implementations have been developed to improve their accuracy and efficiency. In this communication the equivalence between some of these recently reported techniques and conventional schemes is shown. More specifically, we prove that there are four-stage split-step (4SS)-FDTD algorithms that can be reinterpreted as classic two-stage split-step (2SS)-FDTD schemes yielding the same local truncation errors and numerical dispersion relationships. The analytical results are validated by numerical simulations. [ABSTRACT FROM PUBLISHER]

The lumped-network finite-difference time-domain (LN-FDTD) technique is an extension of the conventional FDTD method that enables the incorporation of linear one-port LNs in a single FDTD cell. This paper studies the stability and the numerical dispersion of this technique. To this end, an isotropic medium that is uniformly loaded with LNs in the x-direction is considered as a working model. The stability analysis, based on the von Neumann method, is performed for general Mth-order LNs and closed-form stability conditions are derived for some particular cases. The numerical dispersion relation is obtained for plane-wave propagation in the proposed LN-loaded medium. It is shown that LNs can be interpreted in terms of an effective frequency-dependent permittivity and, as a consequence, the LN-loaded medium can be viewed as a uniaxial medium. The numerical admittance of the LNs is also obtained showing that, as a side-effect of the time discretization, the LN parameters become frequency-dependent, e.g. for the resistor case, the resistance becomes a function of the frequency. [ABSTRACT FROM AUTHOR]

A numerical dispersion analysis of the alternating-direction implicit finite-difference time-domain method for transverse-electric waves in lossy materials is presented. Two different finite-difference approximations for the conduction terms are considered: the double-average and the synchronized schemes. The numerical dispersion relation is derived in a closed form and validated through numerical simulations. This study shows that, despite its popularity, the accuracy of the double-average scheme is sensitive to how well the relaxation-time constant of the material is resolved by the time step. Poor resolutions lead to unacceptably large numerical errors. On the other hand, for good conductors, the synchronized scheme allows stability factors as large as 100 to be used without deteriorating the accuracy significantly. [ABSTRACT FROM AUTHOR]

This paper studies the stability and numerical dispersion of an extension of the original finite-difference time-domain (FDTD) method to incorporate magnetized ferrites. This extension is based on discretizing the ferrite equations by means of central differences and averages. Both partially magnetized and saturated ferrites are considered. With the aim of studying the numerical features of the resulting FDTD algorithms, we have considered the propagation of plane-waves along longitudinally magnetized ferrite materials. This is a simple 1D problem that enables the numerical properties of the algorithms to be studied analytically. A von Neumann stability analysis shows that the stability condition of the original FDTD method is preserved and that the algorithms do not exhibit numerical dissipation. The accuracy of the numerical results is not deteriorated with respect to those obtained in the demagnetized case. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper introduces an extension of the original finite-difference time-domain (FDTD) method for modeling double-negative media characterized by high-order frequency-dependent permittivity and permeability. The approach basically consists of adding electric and magnetic current densities to Maxwell's curl equations and considering Ohm's law as a constitutive relationship. Current densities are discretized by using a weighted average in time and Ohm's law by applying the Mobius transformation technique. The extended FDTD formulation is validated and its numerical features are carefully examined. More specifically, analytical stability conditions are derived for several types of double-negative media and the numerical dissipation issue is discussed. In addition, the numerical dispersion equation for general high-order double-negative media is given and the order of accuracy of the scheme is studied. Finally, the definition of numerical refractive index is addressed and it is shown that, when the discretization parameters of the problem are not properly chosen, a negative refractive index may become a positive one in the discrete world, thus changing the physics of the problem. [ABSTRACT FROM AUTHOR]

A multiresolution in time domain method is used to model the propagation of transient signals through dispersive chiral media. The modeling of these media requires the computation of convolution integrals, whose resolution level may be increased by introducing wavelets in the time dependence of the fields. [ABSTRACT FROM AUTHOR]

A transmission-line matrix model suitable to model the propagation of electromagnetic (EM) waves in hi-isotropic media is presented. The main characteristic of the EM response of such complex media is the cross coupling of the EM field vectors in their constitutive relations. In this study, the angle tilt between electric and magnetic field vectors, the intrinsic impedances, the effective parameters of the medium, and the rotation of the polarization plane are computed. The results are in very good agreement with the theoretical solution. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel finite-difference time-domain model of transient wave propagation in general dispersive bi-isotropic media with losses. The special properties of these materials may lead to new applications in microwave and millimeter-wave technology. While their frequency-domain properties have been well described in the literature, their time-domain behavior has only been modeled thus far for special sub-classes and monochromatic time dependence. We have validated our method by first computing time-harmonic wave propagation through a bi-isotropic medium and comparing it with analytical results. Agreement is typically better than 1%. We have then computed transient field propagation in a general lossy dispersive bi-isotropic medium. [ABSTRACT FROM AUTHOR]

The incorporation of non‐benzenoid motifs in graphene nanostructures significantly impacts their properties, making them attractive for applications in carbon‐based electronics. However, understanding how specific non‐benzenoid structures influence their properties remains limited, and further investigations are needed to fully comprehend their implications. Here, we report an on‐surface synthetic strategy toward fabricating non‐benzenoid nanographenes containing different combinations of pentagonal and heptagonal rings. Their structure and electronic properties were investigated via scanning tunneling microscopy and spectroscopy, complemented by computational investigations. After thermal activation of the precursor P on the Au(111) surface, we detected two major nanographene products. Nanographene Aa−a embeds two azulene units formed through oxidative ring‐closure of methyl substituents, while Aa−s contains one azulene unit and one Stone‐Wales defect, formed by the combination of oxidative ring‐closure and skeletal ring‐rearrangement reactions. Aa−a exhibits an antiferromagnetic ground state with the highest magnetic exchange coupling reported up to date for a non‐benzenoid containing nanographene, coexisting with side‐products with closed shell configurations resulted from the combination of ring‐closure and ring‐rearragement reactions (Ba−a, Ba−s, Bs‐a and Bs−s). Our results provide insights into the single gold atom assisted synthesis of novel NGs containing non‐benzenoid motifs and their tailored electronic/magnetic properties. [ABSTRACT FROM AUTHOR]

The incorporation of non‐benzenoid motifs in graphene nanostructures significantly impacts their properties, making them attractive for applications in carbon‐based electronics. However, understanding how specific non‐benzenoid structures influence their properties remains limited, and further investigations are needed to fully comprehend their implications. Here, we report an on‐surface synthetic strategy toward fabricating non‐benzenoid nanographenes containing different combinations of pentagonal and heptagonal rings. Their structure and electronic properties were investigated via scanning tunneling microscopy and spectroscopy, complemented by computational investigations. After thermal activation of the precursor P on the Au(111) surface, we detected two major nanographene products. Nanographene Aa−a embeds two azulene units formed through oxidative ring‐closure of methyl substituents, while Aa−s contains one azulene unit and one Stone‐Wales defect, formed by the combination of oxidative ring‐closure and skeletal ring‐rearrangement reactions. Aa−a exhibits an antiferromagnetic ground state with the highest magnetic exchange coupling reported up to date for a non‐benzenoid containing nanographene, coexisting with side‐products with closed shell configurations resulted from the combination of ring‐closure and ring‐rearragement reactions (Ba−a, Ba−s, Bs‐a and Bs−s). Our results provide insights into the single gold atom assisted synthesis of novel NGs containing non‐benzenoid motifs and their tailored electronic/magnetic properties. [ABSTRACT FROM AUTHOR]

On-surface synthesis has recently become an essential approach toward the formation of carbon-based nanostructures. Special emphasis is set on the synthesis of π-conjugated polymers taking into consideration their relevance and potential in organic electronics, optoelectronics and spintronics. Here, we report the on-surface synthesis of conjugated ladder polymers consisting of pentacene units doubly-linked via ethynylene-like bonds on the Au(111) surface under ultra-high vacuum conditions. To this aim, we have sublimed pentacene-like precursors equipped with four :CBr2 functional groups to steer the desired reaction upon annealing on the surface. The atomically precise structure of the obtained polymers has been unambiguously characterized via low-temperature scanning tunneling microscopy and non-contact atomic force microscopy. In addition, scanning tunneling spectroscopy complemented with density-functional theory calculations reveal the narrow bandgap of the polymer. Our results provide potential for the synthesis of π-conjugated polymers with prospects in functional carbon-based nanomaterials that exploit multiple connections between molecular backbones. [ABSTRACT FROM AUTHOR]

Nanocars are carbon‐based single‐molecules with a precise design that facilitates their atomic‐scale control on a surface. The rational design of these molecules is important in atomic and molecular‐scale manipulation to advance the development of molecular machines, as well as for a better understanding of self‐assembly, diffusion and desorption processes. Here, we introduce the molecular design and construction of a collection of minimalistic nanocars. They feature an anthracene chassis and four benzene derivatives as wheels. After sublimation and adsorption on an Au(111) surface, we show controlled and fast manipulation of the nanocars along the surface using the tip of a scanning tunneling microscope (STM). The mechanism behind the successful displacement is the induced dipole created over the nanocar by the STM tip. We utilized carbon monoxide functionalized tips both to avoid decomposition and accidentally picking the nanocars up during the manipulation. This strategy allowed thousands of maneuvers to successfully win the Nanocar Race II championship. [ABSTRACT FROM AUTHOR]

Nanocars are carbon‐based single‐molecules with a precise design that facilitates their atomic‐scale control on a surface. The rational design of these molecules is important in atomic and molecular‐scale manipulation to advance the development of molecular machines, as well as for a better understanding of self‐assembly, diffusion and desorption processes. Here, we introduce the molecular design and construction of a collection of minimalistic nanocars. They feature an anthracene chassis and four benzene derivatives as wheels. After sublimation and adsorption on an Au(111) surface, we show controlled and fast manipulation of the nanocars along the surface using the tip of a scanning tunneling microscope (STM). The mechanism behind the successful displacement is the induced dipole created over the nanocar by the STM tip. We utilized carbon monoxide functionalized tips both to avoid decomposition and accidentally picking the nanocars up during the manipulation. This strategy allowed thousands of maneuvers to successfully win the Nanocar Race II championship. [ABSTRACT FROM AUTHOR]

This article presents a novel mathematical model to describe the spread of an infectious disease in the presence of social and health events: it uses 15 compartments, 7 convolution integrals and 4 types of infected individuals, asymptomatic, mild, moderate and severe. A unique feature of this work is that the convolutions and the compartments have been selected to maximize the number of independent input parameters, leading to a 56-parameter model where only one had to evolve over time. The results show that 1) the proposed mathematical model is flexible and robust enough to describe the complex dynamic of the pandemic during the first three waves of the COVID-19 spread in the region of Madrid (Spain) and 2) the proposed model allows us to calculate the number of asymptomatic individuals and the number of persons who presented antibodies during the first waves. The study shows that the following results are compatible with the reported data: close to 28% of the infected individuals were asymptomatic during the three waves, close to 29% of asymptomatic individuals were detected during the subsequent waves and close to 26% of the Madrid population had antibodies at the end of the third wave. This calculated number of persons with antibodies is in great agreement with four direct measurements obtained from an independent sero-epidemiological research. In addition, six calculated curves (total number of confirmed cases, asymptomatic who are confirmed as positive, hospital admissions and discharges and intensive care units admissions) show good agreement with data from an epidemiological surveillance database. [ABSTRACT FROM AUTHOR]

Atomic scale defects significantly affect the mechanical, electronic, and optical properties of π‐conjugated polymers. Here, isolated atomic‐scale defects are deliberately introduced into a prototypical anthracene‐ethynylene π‐conjugated polymer, and its local density of states is carefully examined on the atomic scale to show how individual defects modify the inherent electronic and magnetic properties of this one‐dimensional systems. Scanning tunneling and atomic force microscopy experiments, supplemented with density functional theory calculations, reveal the existence of a sharp electronic resonance at the Fermi energy around certain defects, which is associated with the formation of a local magnetic moment accompanied by substantial mitigation of the mobility of charge carriers. While defects in traditionally synthesized polymers lead to arbitrary conformations, the presented results clearly reflect the preferential formation of low dimensional defects at specific polymer sites, which may introduce the possibility of engineering macroscopic defects in surface‐synthesized conjugated polymers. [ABSTRACT FROM AUTHOR]

The synthesis of long n‐peri‐acenes (n‐PAs) is challenging as a result of their inherent open‐shell radical character, which arises from the presence of parallel zigzag edges beyond a certain n value. They are considered as π‐electron model systems to study magnetism in graphene nanostructures; being potential candidates in the fabrication of optoelectronic and spintronic devices. Here, we report the on‐surface formation of the largest pristine member of the n‐PA family, i.e. peri‐heptacene (n=7, 7‐PA), obtained on an Au(111) substrate under ultra‐high vacuum conditions. Our high‐resolution scanning tunneling microscopy investigations, complemented by theoretical simulations, provide insight into the chemical structure of this previously elusive compound. In addition, scanning tunneling spectroscopy reveals the antiferromagnetic open‐shell singlet ground state of 7‐PA, exhibiting singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 49 meV. [ABSTRACT FROM AUTHOR]

The synthesis of long n‐peri‐acenes (n‐PAs) is challenging as a result of their inherent open‐shell radical character, which arises from the presence of parallel zigzag edges beyond a certain n value. They are considered as π‐electron model systems to study magnetism in graphene nanostructures; being potential candidates in the fabrication of optoelectronic and spintronic devices. Here, we report the on‐surface formation of the largest pristine member of the n‐PA family, i.e. peri‐heptacene (n=7, 7‐PA), obtained on an Au(111) substrate under ultra‐high vacuum conditions. Our high‐resolution scanning tunneling microscopy investigations, complemented by theoretical simulations, provide insight into the chemical structure of this previously elusive compound. In addition, scanning tunneling spectroscopy reveals the antiferromagnetic open‐shell singlet ground state of 7‐PA, exhibiting singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 49 meV. [ABSTRACT FROM AUTHOR]

The atomically precise control over the size, shape and structure of nanographenes (NGs) or the introduction of heteroatom dopants into their sp2‐carbon lattice confer them valuable electronic, optical and magnetic properties. Herein, we report on the design and synthesis of a hexabenzocoronene derivative embedded with graphitic nitrogen in its honeycomb lattice, achieved via on‐surface assisted cyclodehydrogenation on the Au(111) surface. Combined scanning tunnelling microscopy/spectroscopy and non‐contact atomic force microscopy investigations unveil the chemical and electronic structures of the obtained dicationic NG. Kelvin probe force microscopy measurements reveal a considerable variation of the local contact potential difference toward lower values with respect to the gold surface, indicative of its positive net charge. Altogether, we introduce the concept of cationic nitrogen doping of NGs on surfaces, opening new avenues for the design of novel carbon nanostructures. [ABSTRACT FROM AUTHOR]

The atomically precise control over the size, shape and structure of nanographenes (NGs) or the introduction of heteroatom dopants into their sp2‐carbon lattice confer them valuable electronic, optical and magnetic properties. Herein, we report on the design and synthesis of a hexabenzocoronene derivative embedded with graphitic nitrogen in its honeycomb lattice, achieved via on‐surface assisted cyclodehydrogenation on the Au(111) surface. Combined scanning tunnelling microscopy/spectroscopy and non‐contact atomic force microscopy investigations unveil the chemical and electronic structures of the obtained dicationic NG. Kelvin probe force microscopy measurements reveal a considerable variation of the local contact potential difference toward lower values with respect to the gold surface, indicative of its positive net charge. Altogether, we introduce the concept of cationic nitrogen doping of NGs on surfaces, opening new avenues for the design of novel carbon nanostructures. [ABSTRACT FROM AUTHOR]

A TLM model suitable to simulate the propagation of electromagnetic waves in Tellegen media is presented. The angle tilt between electromagnetic field vectors, the intrinsic impedances and the effective parameters of the medium are computed. The results for a monochromatic source are in very good agreement with the analytical solution. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 438–441, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11404 [ABSTRACT FROM AUTHOR]

Background: The use of electronic media is widespread among young people and is a potential tool for the perpetration of intimate-partner violence (IPV) towards women. The aim of this study is to validate two questions focused on harassment and control by electronic tools (HCE-2) as a screening tool for the detection of IPV in young women.Methods: The data source was the third Community of Madrid IPV survey in 2014. The screening tool consisted of two questions with five possible answers prepared by a group of experts. As the gold standard we used the definition of intimate partner violence based on a 26- question survey. The validity indices (with 95% confidence intervals) were compared between two age groups: 18-24 and 25-29 years.Results: Six hundred ninty-four women were sampled. The response rate was 68.7%, and 477 surveys were analyzed. The prevalence of IPV was 10.7% (95% CI: 8.2-13.8). HCE-2 was positive in 5.9% (95% CI: 4.1-8.4). The overall efficiency of the test was 93.5% (95% CI: 91.1-96.7), sensitivity 47.1% (95% CI: 33.7-60.8), specificity 99.1% (95% CI: 97.5-99.6), and positive predictive value 85.7% (95% CI: 67.1-94.6). The best validity indices of the questionnaire were observed in women aged 18 to 24 years: overall efficiency of the test 95.1% (95% CI: 92.6-97.7), sensitivity 62.5% (95% CI: 44.5-77.6), specificity 99.6% (95% CI: 97.0-99.9), and positive predictive value 95.2% (95% CI: 71.7-99.4).Conclusions: The existing need to improve the detection of IPV in young women and the good validity indices observed here justify the recommendation of the HCE-2 questionnaire as a screening tool in young women. [ABSTRACT FROM AUTHOR]

In this paper, a novel TLM algorithm for electromagnetic wave propagation in chiral media is presented. One of the main characteristics of the electromagnetic response of such media is the rotation of the polarization plane. The obtained TLM results for a monochromatic source are compared with the theoretical solution, and very good agreement is achieved. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 180–182, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20937 [ABSTRACT FROM AUTHOR]

Molecular Machinery, Nanocars, Scanning Tunneling Microscopy, [4+2] Cycloaddition Inside Cover: Design and Manipulation of a Minimalistic Hydrocarbon Nanocar on Au(111) (Angew. Keywords: Molecular Machinery; Nanocars; Scanning Tunneling Microscopy; [4+2] Cycloaddition EN Molecular Machinery Nanocars Scanning Tunneling Microscopy [4+2] Cycloaddition 1 1 1 01/31/23 20230201 NES 230201 B A minimalistic hydrocarbon nanocar b was synthesized, deposited on a Au(111) surface, and driven by a STM tip thanks to electrostatic interactions. [Extracted from the article]

Molecular Machinery, Nanocars, Scanning Tunneling Microscopy, [4+2] Cycloaddition This nanomachine was able to win the Nanocar Race II championship, as reported by Jonas Björk, Emilio M. Pérez, David Écija et al. in their Research Article (e202212395). Keywords: Molecular Machinery; Nanocars; Scanning Tunneling Microscopy; [4+2] Cycloaddition EN Molecular Machinery Nanocars Scanning Tunneling Microscopy [4+2] Cycloaddition 1 1 1 01/31/23 20230201 NES 230201 B A minimalistic hydrocarbon nanocar b was synthesized, deposited on a Au(111) surface, and driven by a STM tip thanks to electrostatic interactions. [Extracted from the article]

Details of this research can be found in the Communication by José I. Urgel, Pavel Jelínek, Xinliang Feng, David Écija, and co-workers (e202114983). Keywords: Carbon Magnetism; Open-Shell Character; Periacenes; Scanning Tunneling Microscopy; Surface Chemistry EN Carbon Magnetism Open-Shell Character Periacenes Scanning Tunneling Microscopy Surface Chemistry 1 1 1 06/01/22 20220607 NES 220607 B The precursor b 4,5,9,10-tetrakis(3-methylnaphthalen-2-yl)pyrene is synthesized in solution, sublimed on an Au(111) substrate under ultrahigh vacuum conditions, and converted into the I peri i -heptacene molecule by thermal activation via surface-assisted oxidative ring-closure and cyclodehydrogenation reactions. Carbon Magnetism, Open-Shell Character, Periacenes, Scanning Tunneling Microscopy, Surface Chemistry. [Extracted from the article]

Keywords: Carbon Magnetism; Open-Shell Character; Periacenes; Scanning Tunneling Microscopy; Surface Chemistry EN Carbon Magnetism Open-Shell Character Periacenes Scanning Tunneling Microscopy Surface Chemistry 1 1 1 06/01/22 20220607 NES 220607 B Die Vorstufe b 4,5,9,10-Tetrakis(3-methylnaphthalen-2-yl)pyren wurde in Lösung synthetisiert, unter Ultrahochvakuumbedingungen auf einem Au(111)-Substrat sublimiert und durch thermische Aktivierung mittels oberflächenunterstützter oxidativer Ringschluss- und Cyclodehydrierungsreaktionen in das Periheptacen-Molekül umgewandelt. Carbon Magnetism, Open-Shell Character, Periacenes, Scanning Tunneling Microscopy, Surface Chemistry Einzelheiten zu dieser Forschung finden sich in der Zuschrift von José I. Urgel, Pavel Jelínek, Xinliang Feng, David Écija et al. (e202114983). [Extracted from the article]

The synthesis of long n‐peri‐acenes (n‐PAs) is challenging as a result of their inherent open‐shell radical character, which arises from the presence of parallel zigzag edges beyond a certain n value. They are considered as π‐electron model systems to study magnetism in graphene nanostructures; being potential candidates in the fabrication of optoelectronic and spintronic devices. Here, we report the on‐surface formation of the largest pristine member of the n‐PA family, i.e. peri‐heptacene (n=7, 7‐PA), obtained on an Au(111) substrate under ultra‐high vacuum conditions. Our high‐resolution scanning tunneling microscopy investigations, complemented by theoretical simulations, provide insight into the chemical structure of this previously elusive compound. In addition, scanning tunneling spectroscopy reveals the antiferromagnetic open‐shell singlet ground state of 7‐PA, exhibiting singlet–triplet spin‐flip inelastic excitations with an effective exchange coupling (Jeff) of 49 meV. [ABSTRACT FROM AUTHOR]

The synthesis of nanographenes (NGs) with open-shell ground states have recently attained increasing attention in view of their interesting physicochemical properties and great prospects in manifold applications as suitable materials within the rising field of carbon-based magnetism. A potential route to induce magnetism in NGs is the introduction of structural defects, for instance non-benzenoid rings, in their honeycomb lattice. Here, we report the on-surface synthesis of three open-shell non-benzenoid NGs (A1, A2 and A3) on the Au(111) surface. A1 and A2 contain two five- and one seven-membered rings within their benzenoid backbone, while A3 incorporates one five-membered ring. Their structures and electronic properties have been investigated by means of scanning tunneling microscopy, noncontact atomic force microscopy and scanning tunneling spectroscopy complemented with theoretical calculations. Our results provide access to open-shell NGs with a combination of non-benzenoid topologies previously precluded by conventional synthetic procedures. [ABSTRACT FROM AUTHOR]

Background: The proportion of smokers and the number of cigarettes consumed per person-year in Madrid is above the European average. To evaluate the impact of smoking in public health smoking attributable mortality was estimated for 1998 and for changes since 1992. Methods: The number of smoking attributable deaths and years of potential life lost attributable to cigarette smoking for 1992 and 1998 by gender and age group were estimated, based on the population attributable fraction. The relative risks of the Cancer Prevention Study II were used. To compare the two periods of study, a Poisson regression analysis adjusted by age was applied. Results: In 1998, 15.9% of total mortality in the population older than 34 years was attributable to smoking. Lung cancer and chronic obstructive pulmonary disease are the main causes of death in both genders. In the period studied, 1992-1998, the adjusted rates diminished in men in both age groups, while in women they increased in the age group 35 to 64 years. The mortality from lung cancer remained stable in men, increasing in women by 12%. The years of potential life lost decreased by 14% in men and increased by 42% in women. Conclusions: One in four deaths in men and one in 36 deaths in women are attributed to cigarette smoking. The smoking attributable mortality in males has tended to stabilize, while in women premature mortality is increasing. [ABSTRACT FROM AUTHOR]

The accurate time-domain simulation of the nonlinear dynamics of circuits containing distributed elements is of great interest. Specially at high frequencies, it is essential to consider phenomena, such as crosstalk, packaging effects, and electromagnetic interaction between active and passive elements. These effects are mainly due to the distribute components of the circuit. Therefore, the accuracy in the instability or oscillation analysis of nonlinear circuits is often limited by the models used for such elements. Commercial simulators based on the equivalent-circuit approach hardly take into account the mentioned effects. In this work, the finite-difference time-domain (FDTD) method is applied to the nonlinear simulation of a diode-based microstrip circuit exhibiting a parametric frequency division by two. The FDTD method rigorously solves Maxwell's curl equations in the time domain providing a full-wave characterization of the distributed elements of the circuit. In the example considered, a relatively low operating frequency has been selected to allow a reliable comparison between the results obtained by the proposed technique and those provided by a circuit-based commercial simulator. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1300–1302, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23352 [ABSTRACT FROM AUTHOR]

© 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1132, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23280 [ABSTRACT FROM AUTHOR]