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Historically, traditional laboratory experiments have been given a central and distinctive role in science education. However, virtual laboratories have received considerable attention over the past several years in different areas of knowledge. The main aim of this study is to analyse the impact of the use of both traditional and virtual laboratories in Basic Science Subjects (BSS) in Health Sciences university degrees. For this reason, we have described and analysed different variables such as level of satisfaction, increase in perceived motivation and increase in perceived academic performance. Throughout the academic course the pupils who took part in our study carried out laboratory experiments both traditionally and virtually in different BSS, and they completed a questionnaire to assess their satisfaction and the impact of both approaches at the end of the course. The results point to statistically significant differences in favour of traditional laboratories in all the studied variables, together with some differences between male and female students. In general, students showed more positive attitudes towards traditional experiments. These results emphasize the importance of carrying out hands-on experiments to boost student motivation and perceived performance. XOTRIO1628, 2017, Laureate Education Inc. 1.343 JCR (2021) Q3, 73/94 Biology 0.427 SJR (2021) Q2, 105/322 Agricultural and Biological Sciences (miscellaneous) No data IDR 2021 UEV

Background: The COVID-19 pandemic turned the world towards digitized learning. In the present day, the increased demand for online education produces an even greater request for quality courses and well-established processes for teaching relevant contents. Simultaneously, modern pedagogical trends promote the application of gamification as a tool for improving motivation, developing new skills and strengthening knowledge retention. In this context, Digital Escape Rooms have become an educational tool of great interest, in terms of new approaches to game-based learning. Objective: The general objective is to evaluate the effectiveness of a Digital Escape Room to facilitate the acquisition and the maintenance of students' knowledge applied in Biomedical Sciences. Methods: An educational game, the Genetics Escape Room, will be created with Genially. It will be based on 4 contents: genome, mutations, polymorphism and genetically transmitted diseases. The participants will consist of ca. 240 first year students enrolled in “Cellular Biology and Human genetics” in Dentistry Degree. They will be divided into an experimental group that will play Escape Room, and a control group that will visualize a virtual master class about the same 4 contents of the Escape Room. To evaluate students´ knowledge, all participants will complete a 20-question test (5 questions for each content) performed at three different time points. Firstly, two weeks before the experiment as pre-test, to assess students’ previous knowledge, secondly at the end of the gamification or the virtual class (post-test 1), and finally in two weeks’ time to evaluate knowledge retention when compared the two methods (post-test 2). To evaluate students’ opinion about the experience, a perception survey will be completed. Hypothesis: The following hypotheses are going to be considered: - We expect that the use of the escape room may well be equally as effective as a master class in increasing student knowledge and understanding. - A higher degree of retention of knowledge for lifelong learning is expected among students who play escape room. - We expect a higher motivation and an increase in the appreciation of Human Genetics subject among students who take part in the escape room. 2021/UEM22 No data 2021 UEV

A proposal is made to employ stochastic models, based on diffusion processes, to represent the evolution of the SARS-CoV-2 virus pandemic. Specifically, two diffusion processes are proposed whose mean functions obey multi-sigmoidal Gompertz and Weibull-type patterns. Both are constructed by introducing polynomial functions in the ordinary differential equations that originate the classical Gompertz and Weibull curves. The estimation of the parameters is approached by maximum likelihood. Various associated problems are analyzed, such as the determination of initial solutions for the necessary numerical methods in practical cases, as well as Bayesian methods to determine the degree of the polynomial. Additionally, strategies are suggested to determine the best model to fit specific data. A practical case is developed from data originating from several Spanish regions during the first two waves of the COVID-19 pandemic. The determination of the inflection time instants, which correspond to the peaks of infection and deaths, is given special attention. To deal with this particular issue, point estimation as well as first-passage times have been considered., Ministerio de Economía, Industria y Competitividad, Spain, under Grant MTM2017-85568-P, FEDER, Consejería de Economía y Conocimiento de la Junta de Andalucía, Spain under Grant A-FQM-456-UGR18

We consider a non homogeneous Gompertz diffusion process whose parameters are modified by generally time-dependent exogenous factors included in the infinitesimal moments. The proposed model is able to describe tumor dynamics under the effect of anti-proliferative and/or cell death-induced therapies. We assume that such therapies can modify also the infinitesimal variance of the diffusion process. An estimation procedure, based on a control group and two treated groups, is proposed to infer the model by estimating the constant parameters and the time-dependent terms. Moreover, several concatenated hypothesis tests are considered in order to confirm or reject the need to include time-dependent functions in the infinitesimal moments. Simulations are provided to evaluate the efficiency of the suggested procedures and to validate the testing hypothesis. Finally, an application to real data is considered.

In experimental studies on tumor growth, whenever the time evolution of the relative volume of a tumor in an untreated (control) group can be fitted by a Gompertz diffusion process there is a possibility that an antiproliferative therapy, which modifies the growth rate of the process that fits the treated group, may also affect its variability. The present paper proposes several procedures for the estimation of the time function included in the infinitesimal variance of the new process, as well as the time function affecting the growth rate (which is included in the infinitesimal mean). Also, a hypothesis testing is designed to confirm or refute the need for including such a time-dependent function in the infinitesimal variance. In order to validate and compare the proposed procedures a simulation study has been carried out. In addition, a proposal is made for a strategy aimed at finding the optimal combination of procedures for each case. A real data application concerning the effects of cisplatin on a patient-derived xenograft (PDX) tumor model showcases the advantages of this model over others that have been used in the past.

[EN] Traditional laboratory experiments are critical to the learning process across all areas and levels of study in science subjects. However, along with hands-on experiments, virtual labs have received considerable attention over the past several years due to the popularisation of ICT tools in Education, which may help teachers consider multiple learning styles to pursue meaningful learning. In this regard, studies concerning pupils’ experiences with both approaches are needed. The main aim of this study is to analyse the impact of the use of both virtual and hands-on labs in basic science subjects (BSS) in Health Sciences university degrees. For this reason, we have analysed different variables: general assessment, level of satisfaction, increase in motivation and increase in academic performance concerning BSS, as well as gender differences in the perception of both methodologies. A total of 129 undergraduate students from one Spanish university (degree in Dentistry) participated in the study. The results point out to statistically significant differences in favour of traditional labs in all the considered parameters. In conclusion, the results point out the importance of carrying out hands-on experiments to boost students’ motivation and performance, [ES] Las prácticas de laboratorio tradicionales juegan un papel protagonista en la enseñanza de las ciencias en todas las áreas y niveles. Sin embargo, en los últimos años la popularidad de los laboratorios virtuales ha aumentado significativamente, debido a que la aplicación de las herramientas TIC en educación permite atender adecuadamente a la diversidad del alumnado y fomentar el aprendizaje activo. En este sentido, resulta necesario estudiar las experiencias del alumnado con ambos enfoques. El principal objetivo de este estudio es analizar el impacto de los laboratorios virtuales y tradicionales en asignaturas de Ciencias Básicas (CCBB) en un grado de Ciencias de la Salud en el contexto universitario. Para ello se ha estudiado la valoración del alumnado, su grado de satisfacción general, su motivación y su rendimiento en las asignaturas de CCBB, así como la existencia de posibles diferencias de género. Los participantes del estudio fueron 129 estudiantes del grado en Odontología de una universidad española. Los resultados indican que existen diferencias significativas a favor de las prácticas tradicionales en todas las variables estudiadas. Como conclusión, se resalta la importancia de fomentar las prácticas tradicionales en grados de Salud para potenciar la motivación y el rendimiento del alumnado.

We report the process of singlet exciton fission with high-yield upon photoexcitation of a quinoidal thiophene molecule. Efficient ultrafast triplet photogeneration and its yield are determined by photoinduced triplet-triplet absorption, flash photolysis triplet lifetime measurements, as well as by femtosecond time-resolved transient absorption and fluorescence methods. These experiments show that optically excited quinoidal bithiophene molecule undergoes ultrafast formation of the triplet-like state with the lifetime ∼57 μs. CASPT2 and RAS-SF calculations have been performed to support the experimental findings. To date, high singlet fission rates have been reported for crystalline and polycrystalline materials, whereas for covalently linked dimers and small oligomers it was found to be relatively small. In this contribution, we show an unprecedented quantum yield of intramolecular singlet exciton fission of ∼180% for a quinoidal bithiophene system.

Version 1.2 of the fptdApprox R package implemented a general heuristic strategy for the efficient application of numerical schemes aimed at solving Volterra integral equations whose solutions are first-passage-time (f.p.t.) density functions for a diffusion process. This paper presents a new version of this package, developed with the goal of addressing interesting f.p.t. problems that cannot be solved with the previous version. More specifically, it addresses f.p.t. problems for diffusion processes defined by means of not-closed-form time expressions (which appear in application fields such as tumor growth or the evolution of economic variables), and unconditioned f.p.t. problems for diffusion processes with non-degenerate initial distributions (of great interest in the study of population growth in Biology and Ecology). Here, the functionality of this new version is described, with a focus on its numerical and computational aspects. Moreover, by means of several examples, we show how the package can be used to solve problems such as those mentioned above.

The authors would like to thank the three anonymous reviewers for their suggestions that have improved the content of the paper., The behaviour of many dynamic real phenomena shows different phases, with each one following a sigmoidal type pattern. This requires studying sigmoidal curves with more than one inflection point. In this work, a diffusion process is introduced whose mean function is a curve of this type, concretely a transformation of the well-known Gompertz model after introducing in its expression a polynomial term. The maximum likelihood estimation of the parameters of the model is studied, and various criteria are provided for the selection of the degree of the polynomial when real situations are addressed. Finally, some simulated examples are presented., Ministerio de Economía, Industria y Competitividad, Spain, under Grant MTM2017-85568-P.

Light-emitting electrochemical cells (LECs) based on cyanine molecules were prepared. High photoluminescence quantum yields were obtained for host-guest films using two cyanine dyes, reaching 27%. Sandwiching these films in between two electrodes allows for very stable near-infrared emission with a maximum radiant flux of 1.7 W m(-2) at an external quantum efficiency of 0.44%.

In light-emitting electrochemical cells, the lifetime of the device is intrinsically linked to the stability of the phosphorescent emitter. In this study, we present a series of ionic iridium(III) emitters based on cyclometalating phenylpyridine ligands whose fluorine substituents are varied in terms of position and number. Importantly, despite these structural modifications, the emitters exhibit virtually identical electrochemical and spectroscopic properties, which allows for proper comparison in functional devices. Quantum chemical calculations support the properties measured in solution and suggest great similarities regarding the electronic structures of the emitters. In electroluminescent devices the initial luminance efficiency, and efficacy are also relatively unaffected throughout the series. However, a shorter device lifetime is obtained upon increasing the fluorine content of the emitter, which suggests drawbacks of such electron withdrawing substituents for the design of ionic iridium(III) emitters.

Proton/hydrogen-transfer processes have been broadly studied in the past 50 years to explain the photostability and the spontaneous tautomerism in the DNA base pairs. In the present study, the CASSCF/CASPT2 methodology is used to map the two-dimensional potential energy surfaces along the stretched NH reaction coordinates of the guanine–cytosine (GC) base pair. Concerted and stepwise pathways are explored initially in vacuo, and three mechanisms are studied: the stepwise double proton transfer, the stepwise double hydrogen transfer, and the concerted double proton transfer. The results are consistent with previous findings related to the photostability of the GC base pair, and a new contribution to tautomerism is provided. The C-based imino-oxo and imino-enol GC tautomers, which can be generated during the UV irradiation of the Watson–Crick base pair, have analogous radiationless energy-decay channels to those of the canonical base pair. In addition, the C-based imino-enol GC tautomer is thermally less stable. A study of the GC base pair is carried out subsequently taking into account the DNA surroundings in the biological environment. The most important stationary points are computed using the quantum mechanics/molecular mechanics (QM/MM) approach, suggesting a similar scenario for the proton/hydrogen-transfer phenomena in vacuo and in DNA. Finally, the static model is complemented by ab initio dynamic simulations, which show that vibrations at the hydrogen bonds can indeed originate hydrogen-transfer processes in the GC base pair. The relevance of the present findings for the rationalization of the preservation of the genetic code and mutagenesis is discussed.

The extended S1/S0 conical intersection seam for the photochemical 2s + 2s, 2s + 2a and 2a + 2a cycloadditions of two ethylene molecules has been documented using the methodology described by Sicilia et al. (J. Chem. Theory Comput. 4, 257 (2008)). Two additional critical points on this prototype crossing seam were found as a result, although both lie more than 100 kcal mol−1 above the rhomboidal crossing located previously, and are not minima in the intersection space. Using VB theory, the branching space conditions for the conical intersection can be derived analytically, in fair agreement with calculated CASSCF results. Woodward–Hoffmann symmetry forbidden and allowed reactions are associated with the same extended conical intersection seam in this case.

This article presents an R package that implements a general heuristic strategy for the efficient application of numerical schemes for solving Volterra integral equations which have as solution first-passage-time density functions associated to certain stochastic processes. Such a strategy is based on the information provided by the First-Passage-Time Location (FPTL) function about the location of the first-passage-time variable, and it is valid for general situations that expand on the particular cases considered in Roman et al. (2008) [10] . Numerical applications are shown to illustrate the validity of the strategy as well as its computational advantages.

The UV photoreactivity of different pyrimidine DNA/RNA nucleobases along the singlet manifold leading to the formation of cyclobutane pyrimidine dimers has been studied by using the CASPT2 level of theory. The initially irradiated singlet state promotes the formation of excimers between pairs of properly oriented nucleobases through the overlap between the π structures of two stacked nucleobases. The system evolves then to the formation of cyclobutane pyrimidine dimers via a shearing-type conical intersection activating a [2 + 2] photocycloaddition mechanism. The relative location of stable excimer conformations or alternative decay channels with respect to the reactive degeneracy region explains the differences in the photoproduction efficiency observed in the experiments for different nucleobases sequences. A comparative analysis of the main structural parameters and energetic profiles in the singlet manifold is carried out for thymine, uracil, cytosine, and 5-methylcytosine homodimers. Thymine and uracil dimers display the most favorable paths, in contrast to cytosine. Methylation of the nucleobases seems to increase the probability for dimerization.

Quantum chemical studies using the accurate CASPT2//CASSCF procedure show that π-stacked interactions in biochromophores such as pyrimidine (Pyr) DNA/RNA nucleobases pairs yield excimer-like situations which behave as precursors of processes like charge transfer (CT) or photoreactivity and are the source of the emissive properties in DNA. Examples are the CT between adjacent DNA nucleobases in a strand of oligonucleotides and the photodimerization taking place in cytosine (C) pairs leading to cyclobutanecytosine (CBC) mutants. These processes take place through nonadiabatic photochemical mechanisms whose evolution is determined by the presence and accessibility of conical intersections (CIs) and other surface crossings between different electronic states.

The ability of furocoumarins to participate in the PUVA (Psoralen + UV-A) therapy against skin disorders and some types of cancer, is analyzed on quantum chemical grounds. The efficiency of the process relies on its capability to populate its lowest triplet excited state, and then either form adducts with thymine which interfere DNA replication or transfer its energy, generating singlet molecular oxygen damaging the cell membrane in photoactivated tissues. By determining the spin–orbit couplings, shown to be the key property, in the intersystem crossing yielding the triplet state of the furocoumarin, the electronic couplings in the triplet–triplet energy transfer process producing the singlet oxygen, and the reaction rates and lifetimes, the efficiency in the phototherapeutic action of the furocoumarin family is predicted as: khellin

The mechanism of the [2 + 2] cycloaddition photoreaction of psoralen and a DNA nucleobase, thymine, cornerstone of the furocoumarin-based PUVA (psoralen + UVA radiation) phototherapy, has been studied by the quantum-chemical multiconfigurational CASPT2 method. Triplet- and singlet-mediated mono- and diadduct formations have been determined to take place via singlet-triplet crossings and conical intersections, correlated with the initially promoted triplet or singlet states in different possible reactive orientations. Pyroneside monoadducts are suggested to be formed in the triplet manifold of the system, and to be less prone to yield diadducts because of the properties of the monoadduct lowest triplet state and the minor accessibility of its excited singlet states. Furan-side monoadducts are better produced in the singlet manifold after reaching a conical intersection with the ground state of the system. From there, the absorption of a second photon would in this case trigger the formation of the diadduct. The proposed mechanisms enable rationalizing the phototherapeutic behavior of several furocoumarins.

Furocoumarins are widely used as photosensitizers in photochemical therapies against different skin disorders such as psoriasis and vitiligo. Absorption of near-UV light by the chromophore triggers a set of photoreactions related to the therapeutic properties of the technique: linkage of a furocoumarin to thymine DNA nucleobases preventing proliferation of pathogenic cells, or generation of highly reactive singlet oxygen in damaged tissues. The family of furocoumarins has been studied in depth for many years seeking a drug having the most remarkable set of properties to act as a photosensitizer. For this purpose, understanding the underlying photochemical mechanisms behind the effectiveness of this therapy is required. We have undertaken a quantum-mechanical study on the photophysics and photochemistry of several relevant furocoumarins: psoralen, 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP), 4,5′,8-trimethylpsoralen (TMP), 3-carbethoxypsoralen (3-CPS), and khellin, analyzing the most efficient way in which the lowest excited triplet state, as protagonist of the photosensitizing action, is populated from the initially promoted singlet states. The results point out to khellin, in particular, and 5-MOP, as the most efficient photosensitizers.

The effect of electromagnetic radiation on biological objects extends from heating to complex photochemistry, and includes DNA alteration, that properly modified in damaged cells may entail beneficial effects. In this regard, psoralen + UV-A (PUVA) therapy, in which furocoumarins, psoralen-like chromophores, are used as photosensitizers and photoreactants with DNA bases, is one of the most promising strategies against a plethora of diseases. Understanding the underlying photochemical mechanisms is crucial to design effective drugs without undesired side effects. We have undertaken a quantum-mechanical study on the photophysics and photochemistry of furocoumarins, analyzing firstly the most efficient way in which the lowest excited triplet state, as protagonist of the photosensitizing action, is populated from the initially promoted singlet states, and secondly the basics of the formation of furocoumarin–DNA photoadducts.

The population of the lowest triplet state of thymine after near-UV irradiation has been established, on the basis of CASPT2//CASSCF quantum chemical calculations, to take place via three distinct intersystem crossing mechanisms from the initially populated singlet bright 1pipi* state. Two singlet-triplet crossings have been found along the minimum-energy path for ultrafast decay of the singlet state at 4.8 and 4.0 eV, involving the lowest 3npi* and 3pipi* states, respectively. Large spin-orbit coupling elements predict efficient intersystem crossing processes in both cases. Another mechanism involving energy transfer from the lowest 1npi* state with much larger spin-orbit coupling terms can also be proposed. The wavelength dependence measured for the triplet quantum yield of pyrimidine nucleobases is explained by the location and accessibility of the singlet-triplet crossing regions.

The efficient population of the low-lying triplet ππ * state of psoralen is studied with the quantum chemical CASPT2 method. Minima, singlet–triplet crossings, conical intersections, and reaction paths on the low-lying singlet and triplet states hypersurfaces of the system have been computed together with electronic energy gaps and spin–orbit coupling terms. A mechanism is proposed, favorable in the gas phase, for efficient deactivation of the initially populated singlet excited ππ * state, starting with an intersystem crossing with an n π * triplet state and evolving via a conical intersection toward the final lowest-lying ππ * triplet state, protagonist of the reactivity of psoralen.

Ir(II) cationic complexes with cyclometalating tetrazolate ligands were prepared for the first time, following a two-step strategy based on (i) a silver-assisted cyclometalation reaction of a tetrazole derivative with IrCl3 affording a bis-cyclometalated solvato-complex P ([Ir(ptrz)(2)(CH3CN)(2)](+), Hptrz = 2-methyl-5-phenyl-2H-tetrazole); (ii) a substitution reaction with five neutral ancillary ligands to get [Ir(ptrz)(2)L](+), with L = 2,2'-bypiridine (1), 4,4'-di-tert-butyl-2,2'-bipyridine (2), 1,10-phenanthroline (3), and 2-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridine (4), and [Ir(ptrz)(2)L-2](+), with L = tertbutyl isocyanide (5). X-ray crystal structures of P, 2, and 3 were solved. Electrochemical and photophysical studies, along with density functional theory calculations, allowed a comprehensive rationalization of the electronic properties of 1-5. In acetonitrile at 298 K, complexes equipped with bipyridine or phenanthroline ancillary ligands (1-3) exhibit intense and structureless emission bands centered at around 540 nm, with metal-to-ligand and ligand-to-ligand charge transfer (MLCT/LLCT) character; their photoluminescence quantum yields (PLQYs) are in the range of 55-70%. By contrast, the luminescence band of 5 is weak, structured, and blue-shifted and is attributed to a ligand-centered (LC) triplet state of the tetrazolate cyclometalated ligand. The PLQY of 4 is extremely low (

The synthesis and characterization of four iridium(iii) complexes [Ir(thpy)2(N^N)][PF6] where Hthpy = 2-(2'-thienyl)pyridine and N^N are 6-phenyl-2,2'-bipyridine (1), 4,4'-di-(t)butyl-2,2'-bipyridine (2), 4,4'-di-(t)butyl-6-phenyl-2,2'-bipyridine (3) or 4,4'-dimethylthio-2,2'-bipyridine (4) are described. The single crystal structures of ligand 4 and the complexes containing the [Ir(thpy)2(1)](+) and [Ir(thpy)2(4)](+) cations have been determined. In [Ir(thpy)2(1)](+), the pendant phenyl ring engages in an intra-cation π-stacking interaction with one of the thienyl rings in the solid state, and undergoes hindered rotation on the NMR timescale in [Ir(thpy)2(1)](+) and [Ir(thpy)2(3)](+). The solution spectra of [Ir(thpy)2(1)][PF6] and [Ir(thpy)2(4)][PF6] show emission maxima around 640 nm and are significantly red-shifted compared with [Ir(thpy)2(2)][PF6] and [Ir(thpy)2(3)][PF6] which have structured emission bands with maxima around 550 and 590 nm. In thin films, the emission spectra of the four complexes are similar with emission peaks around 550 and 590 nm and a shoulder around 640 nm that are reminiscent of the features observed in solution. In solution, quantum yields are low, but in thin films, values range from 29% for [Ir(thpy)2(1)][PF6] to 51% for [Ir(thpy)2(4)][PF6]. Density functional theory calculations rationalize the structured emission observed for the four complexes in terms of the (3)LC nature predicted for the lowest-energy triplet states that mainly involve the cyclometallated [thpy](-) ligands. Support for this theoretical result comes from the observed features of the low temperature (in frozen MeCN) photoluminescence spectra of the complexes. Photoluminescence and electroluminescence spectra of the complexes in a light-emitting electrochemical cell (LEC) device configuration have been investigated. The electroluminescence spectra are similar for all [Ir(thpy)2(N^N)][PF6] complexes with emission maxima at ≈600 nm, but device performances are relatively poor probably due to the poor charge-transporting properties of the complexes.

The photocycloaddition reaction of benzene with ethylene has been studied at the CASSCF level, including the characterization of an extended conical intersection seam. We show that the chemical selectivity is, in part, controlled by this extended conical intersection seam and that the shape of the conical intersection seam can be understood in terms of simple VB arguments. Further, the shape and energetics of the asynchronous segment of the conical intersection seam suggest that 1,2 (ortho) and 1,3 (meta) will be the preferred chemical products with similar weight. The 1,4 (para) point on the conical intersection is higher in energy and corresponds to a local maximum on the seam. VB analysis shows that the pairs of VB structures along this asynchronous seam are the same and thus the shape will be determined mainly by steric effects. Synchronous structures on the seam are higher in energy and belong to a different branch of the seam separated by a saddle point on the seam. On S1 we have documented three mechanistic pathways corresponding to transition states (with low barriers) between the reactants and the conical intersection seam: a mixed asynchronous/synchronous [1,2] ortho path, an asynchronous [1,3] meta path, and a synchronous [1,3] meta path.

There are many areas where Wireless Sensor Networks (WSN) can offer innovative solutions for environmental monitoring applications and the meteorological community, but due to their complexity in terms of energy constraints and low performance devices, very few real deployments can be found. In this paper we will explain in detail the design, implementation and performance evaluation of a sparse WSN that has been working maintenance-free for over 12 months. The network has been designed for environmental monitoring purposes, and several motes, attached to lampposts, accurately measure the Temperature and Relative Humidity at various locations in a local street. Our contribution is an enhanced data gathering application for environmental applications. We will present the different arguments and tradeoffs to be taken into account when designing a network of this type, such as the type of sensors and their calibration, choice of mote and operating system, power supply, special housing required for the mote, data sampling frequency, requirements for the data sink, the structure of the database at the central site, and different issues relating to the exploitation of the meteorological results. We show that a reliable, low cost WSN deployment for environmental monitoring that takes into account the main properties of these networks, such multi-hop routing, low maintenance, low cost and long mote lifetimes, is achievable.

The higher formation yields measured in the ultrafast photoinduced formation of cyclobutane thymine dimers (T T) with respect to those of cytosine (C C) are explained, on the basis of ab initio CASPT2 results, by the existence in thymine of more reactive orientations and a less efficient photoreversibility, whereas in cytosine the funnel toward the photolesion becomes competitive with that mediating the internal conversion of the excited-cytosine monomer.

One of the most important advances in biomedical engineering has been the ability to inspect inside the body without opening it. In this sense, rheoencephalography (REG) is an electromedical technique used to assess the cerebral blood flow (CBF) by noninvasive electrical impedance methods, using electrodes attached to the scalp surface. This technique was first proposed by Polzer and Schuhfried (1950), and emerged as an extrapolation of impedance plethysmography applied to the head. An electric current flowing through a biological tissue causes a potential difference between any pair of electrodes that can be measured. This potential difference depends on the amplitude of the injected current, the shape of the conductor, the arrangement of the electrodes, and the electrical characteristics of the tissue. For instance, the electrical conductivity of the lung tissue is much lower than that of the cerebrospinal fluid (CSF), since alveolar sacs are nonconductive. Furthermore, the electrical conductivity depends on the frequency of the electric current, the orientation of the tissue fibers relative to the current flow, and the amount of extracellular fluid that surrounds the cells. For example, electrical conductivity is higher in the blood than in most tissues, since plasma acts as a truehighway for ions (Malmivuo & Plonsey, 1995).

Psoralen photophysics has been studied on quantum chemistry grounds using the multiconfigurational second-order perturbation method CASPT2. Absorption and emission spectra of the system have been rationalized by computing the energies and properties of the low-lying singlet and triplet excited states. The S1 ππ* state has been determined to be responsible of the lowest absorption and fluorescence bands and to initially carry the population in the photophysical processes related to the phototherapeutic properties of psoralen derivatives. The low-lying T1 ππ* state is, on the other hand, protagonist of the phosphorescence, and its prevalent role in the reactivity of psoralen is suggested to be related to the elongation of the pyrone ring C3–C4 bond, where the spin density is distributed on both carbon atoms. Analysis of energy gaps and spin-orbit coupling elements indicates that the efficient photophysical process leading to the population of the lowest triplet state does not take place at the Franck-Condon region but along the S1 relaxation path. Juan.Serrano@uv.es Luis.Serrano@uv.es Manuela.Merchan@uv.es

In the present work we report the synthesis and the electrochemical, photoluminescent and electroluminescent properties of two new Ru(II) complexes described by the general formula [Ru(phen)2X](2+), where phen is 1,10-phenanthroline. The X ligand consists of a 2,2'-bipyridine (bpy) unit substituted with two phenyl rings connected to the bpy core through a saturated (Lhydro = 4,4'-diphenylethyl-2,2'-bipyridine) or a conjugated (LH = 4,4'-bis(α-styrene)-2,2'-bipyridine) carbon-carbon bridge. The photoluminescent spectra indicate that, both in solution and solid state, the complex bearing the aliphatic substitution bridges exhibits a higher quantum yield and a longer excited state lifetime than the fully conjugated complex. The new complexes were used in light-emitting electrochemical cells (LECs) showing red emission for the complex with the Lhydro ligand and no light emission for the complex incorporating the LH ligand. This and the photophysical properties make it plausible that for these complexes the degree of freedom increases with aliphatic substitution. As a consequence, the negative effect of the auto-quenching processes taking place in solid LEC devices due to the close molecular packing is limited. When compared with the archetype [Ru(phen)3](2+) complex, the complex with aliphatic substitution shows better performance in the device supporting the beneficial effect of the bulky substitution.