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Microgels are soft microparticles that often exhibit thermoresponsiveness and feature a transformation at a critical temperature, referred to as the volume phase transition temperature. The question of whether this transformation occurs as a smooth or as a discontinuous one is still a matter of debate. This question can be addressed by studying individual microgels trapped in optical tweezers. For this aim, composite particles were obtained by decorating pNIPAM microgels with iron oxide nanocubes. These composites become self-heating when illuminated by the infrared trapping laser, featuring Hot Brownian Motion within the trap. Above a certain laser power, a single decorated microgel features a volume phase transition that is discontinuous, while the usual continuous sigmoidal-like dependence is recovered after averaging over different microgels. The collective sigmoidal behavior enables the application of a power-to-temperature calibration and provides the effective drag coefficient of the self-heating microgels, thus establishing these composite particles as potential micro-thermometers and micro-heaters. Moreover, the self-heating microgels also exhibit an unexpected and intriguing bistability behavior above the critical temperature, probably due to partial collapses of the microgel. These results set the stage for further studies and the development of applications based on the Hot Brownian Motion of soft particles.

The interaction of organic molecules with oxonium cations within their solvation shell may lead to the emergence of dynamic supramolecular structures with recurrently changing host–guest chemical identity. We illustrate this phenomenon in benchmark proton-bonded complexes of water with polyether macrocyles. Despite the smaller proton affinity of water versus the ether group, water in fact retains the proton in the form of H3O+, with increasing stability as the coordination number increases. Hindrance in many-fold coordination induces dynamic reversible (ether)·H3O+ ⇌ (etherH+)·H2O interconversion. We perform infrared action ion spectroscopy over a broad spectral range to expose the vibrational signatures of the loose proton bonding in these systems. Remarkably, characteristic bands for the two limiting proton bonding configurations are observed in the experimental vibrational spectra, superimposed onto diffuse bands associated with proton delocalization. These features cannot be described by static equilibrium structures but are accurately modeled within the framework of ab initio molecular dynamics., Area of Physical Chemistry

We present a systematic study of the vapor–liquid equilibria of prolate Kihara fluids embedding both dipole and quadrupole moments Monte Carlo simulations and perturbation theory methods. The agreement between both approaches is good and allows to shed light on some general features of molecular models whose distribution of charge can be modeled as a dipole plus a quadrupole moments. The validation of the equation of state does lead as a byproduct to a rapid, uncommon, and powerful instrument able to widen the frontiers of perturbation theory for molecular fluids and their mixtures.

The biological activity of the macrocycle nonactin is intimately related to its ionophore properties and ability to act as a selective cation carrier. While the focus of most investigations on nonactin has been on the binding of metal cations and small molecular ions, this study pursues the characterization of its inclusion complexes with primary amines with bulky structured side groups of different polarity. To this end, the complexes of nonactin with aniline and with the amino acid L-serine, both in protonated form, are considered as case studies and their relevant coordination arrangements are assessed by means of infrared action spectroscopy, quantum chemical density functional theory and Born-Oppenheimer molecular dynamics. The study suggests that the oxygen atoms from the oxolane (tetrahydrofuran) groups of nonactin constitute the preferential docking sites of the ammonium moiety of the guest cation, although conformational constraints promote interactions with the ester carbonyl backbone groups. In the aniline complex, the benzyl side ring is oriented outwards from the cavity, whereas in the case of L-serine, the side carboxylic acid and alcohol groups participate actively in the coordination process. Interestingly, the accommodation of L-serine is favoured when nonactin adopts an enantiomeric-selective folding, that promotes the tripodal coordination of the protonated amine group with oxolane rings from three nonactinic acid blocks with enantiomeric sequence (+)-(-)-(+), which allows for a facile coordination of the serine side groups. This is recognized as a general feature associated with the alternation of chiral domains in globally achiral natural nonactin, yielding mirror-symmetric complexes with the enantiomers of chiral amines.

This article belongs to the Special Issue Recent Advances in Metallic Nanoparticles as Theranostics Platforms., The development of nanoplatforms prepared to perform both multimodal imaging and combined therapies in a single entity is a fast-growing field. These systems are able to improve diagnostic accuracy and therapy success. Multicomponent Nanoparticles (MCNPs), composed of iron oxide and gold, offer new opportunities for Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) diagnosis, as well as combined therapies based on Magnetic Hyperthermia (MH) and Photothermal Therapy (PT). In this work, we describe a new seed-assisted method for the synthesis of Au@Fe Nanoparticles (NPs) with a flower-like structure. For biomedical purposes, Au@Fe NPs were functionalized with a PEGylated ligand, leading to high colloidal stability. Moreover, the as-obtained Au@Fe-PEG NPs exhibited excellent features as both MRI and CT Contrast Agents (CAs), with high r2 relaxivity (60.5 mM−1⋅s−1) and X-ray attenuation properties (8.8 HU mM−1⋅HU). In addition, these nanoflowers presented considerable energy-to-heat conversion under both Alternating Magnetic Fields (AMFs) (∆T ≈ 2.5 °C) and Near-Infrared (NIR) light (∆T ≈ 17 °C). Finally, Au@Fe-PEG NPs exhibited very low cytotoxicity, confirming their potential for theranostics applications, Financial support was provided the Ministerio de Economía, Industria y Competitividad (CTQ2017-86655-R), Ministerio de Ciencia e Innovación (PID2020-118448RB-C21, PID2020-113108RB-I00 (funded by MCIN/AEI/10.13039/50110001103), and PGC2018-096016-B-I00, the Fondo Social de la DGA (grupos DGA)), and by the Regional Ministry of Health of Andalusia (OH-0026-2018 and PAIDI 2020. P20_00727).

We have sequentially picked up two astrochemically relevant Bronsted acids (methanol and formic acid) on the surface of argon nanoparticles acting as a cold support. Photoionization and electron ionization yield (HCOOH)xH+, (CH3OH)xH+, and mixed protonated clusters. Experiments with perdeuterated methanol CD3OD demonstrate notable proton transfer (PT) to formic acid acting as a proton acceptor in addition to the PT from formic acid which is, perhaps, a more intuitive one. We, therefore, for the first time observed reactions between two different complex molecules adsorbed individually on argon nanoparticles. The experimental results are compared with state-of-the-art quantum chemistry calculations, showing that both CH3OH•+ and HCOOH•+ radical cations resulting from ionization can act as efficient proton donors and neutral CH3OH and HCOOH as proton acceptors. According to the theoretical calculations, the C-H bond cleavage in the radical cation should be more favorable than the O-H bond cleavage. Both channels are observed and distinguished in the experiments with CD3OH and CH3OD. Our detailed mechanism of formation of the CH3O• and CH2OH• radicals contributes to understanding of astrochemistry in the protostellar medium.

Since Arthur Ashkin and coworkers found that focused laser beam could displace and levitate microsized particles, optical tweezers has turn out to be a reliable noncontact tool for 3D manipulation of micro-objects, allows sensing by using only a single particle. The further development of nanophotonics toward higher sensitivities and resolutions continues to stimulate optical trapping of smaller and smaller objects. While applied to sub 100 nm-particles, the optical force starts to get insufficient to trap or manipulate, and the trap potential starts to be comparable to the thermal energy. Although there are a lot of methods that have been proposed to enhance the optical force, few research gets insight of the temperature effect on optical trapping. In this work, we summarize our recent experimental results on thermal sensing experiments in which micro/nanoparticles are used as probes with the aim of providing a contemporary state-of-the-art about the temperature effects in the stability of potential trapping processes.

The proton bond is a paradigmatic quantum molecular interaction and a major driving force of supramolecular chemistry. The ring cavities of crown ethers provide an intriguing environment, promoting competitive proton sharing with multiple coordination anchors. This study shows that protons confined in crown ether cavities form dynamic bonds that migrate to varying pairs of coordinating atoms when allowed by the flexibility of the macrocycle backbone. Prototypic native crown ethers (12-crown-4, 15-crown-5 and 18-crown-6) and aza-crown ethers (cyclen, 1-aza-18-crown-6 and hexacyclen) are investigated. For each system, Infrared action spectroscopy experiments and ab initio Molecular Dynamics computations are employed to elucidate the structural effects associated with proton diffusion and its entanglement with the conformational and vibrational dynamics of the protonated host.

In this study, we report the synthesis of gold-coated iron oxide nanoparticles capped with polyvinylpyrrolidone (Fe@Au NPs). The as-synthesized nanoparticles (NPs) exhibited good stability in aqueous media and excellent features as contrast agents (CA) for both magnetic resonance imaging (MRI) and X-ray computed tomography (CT). Additionally, due to the presence of the local surface plasmon resonances of gold, the NPs showed exploitable “light-to-heat” conversion ability in the near-infrared (NIR) region, a key attribute for effective photothermal therapies (PTT). In vitro experiments revealed biocompatibility as well as excellent efficiency in killing glioblastoma cells via PTT. The in vivo nontoxicity of the NPs was demonstrated using zebrafish embryos as an intermediate step between cells and rodent models. To warrant that an effective therapeutic dose was achieved inside the tumor, both intratumoral and intravenous routes were screened in rodent models by MRI and CT. The pharmacokinetics and biodistribution confirmed the multimodal imaging CA capabilities of the Fe@AuNPs and revealed constraints of the intravenous route for tumor targeting, dictating intratumoral administration for therapeutic applications. Finally, Fe@Au NPs were successfully used for an in vivo proof of concept of imaging-guided focused PTT against glioblastoma multiforme in a mouse model., Spanish Ministry of Economy, Industry and Competitiveness (CTQ2017-86655-R and BIO2017-84246-C2-1-R), Fondo Social de la DGA (grupos DGA) and by the Regional Ministry of Health of Andalusia (OH-0026-2018)., Associate Laboratory for Green Chemistry—LAQV, Applied Molecular Biosciences Unit –UCIBIO, Portuguese national funds from FCT/MCTES (UIDB/04378/2020 and UIDB/50006/2020)

E.X. and R.M. contributed equally to this work. Work partially supported by the Ministerio de Ciencia, Innovacion y Universidades (PID2019-106301RB-I00 and PID2019-105195RA-I00), by the Spanish Ministry of Economy and Competitiveness (MAT2017-85617-R, SEV-2016-0686), by the Comunidad de Madrid (RENIM-CM, B2017/BMD-3867, co-financed by the European Structural and Investment Fund; NANOMAGCOST-CM P2018/NMT-4321), by the European COST Actions CA17115 (MyWave) and CA17140 (Nano2Clinic), by the Spanish Scientific Network HiperNano (RED2018-102626-T) and by the European Commission Horizon 2020 project NanoTBTech (Grant Number: 801305). D.G.-C. acknowledges CAM for funding PEJ-2018-AI/IND-11245. A.B. acknowledges funding from Comunidad de Madrid through TALENTO grant ref. 2019-T1/IND-14014. E.X. is grateful for a Juan de la Cierva Formacion scholarship (FJC2018-036734-I). R.M. acknowledges the support of the European Commission through the European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie Grant agreement N 797945 (LANTERNS). A. E. acknowledges the support from Comunidad de Madrid (Talento project 2018-T1/IND-1005) and from AECC (Ideas Semilla 2019 project). P.R.S. is grateful for a Juan de la Cierva Incorporacion scholarship (IJC2019-041915-I). Procedures involving animal experiments were approved by the regional authority for animal experimentation of the Comunidad de Madrid and were conducted in agreement with the Universidad Autonoma de Madrid Ethics Committee, in compliance with the European Union directives 63/2010UE and Spanish regulation RD 53/2013., Deliberate and local increase of the temperature within solid tumors represents an effective therapeutic approach. Thermal therapies embrace this concept leveraging the capability of some species to convert the absorbed energy into heat. To that end, magnetic hyperthermia (MHT) uses magnetic nanoparticles (MNPs) that can effectively dissipate the energy absorbed under alternating magnetic fields. However, MNPs fail to provide real-time thermal feedback with the risk of unwanted overheating and impeding on-the-fly adjustment of the therapeutic parameters. Localization of MNPs within a tissue in an accurate, rapid, and cost-effective way represents another challenge for increasing the efficacy of MHT. In this work, MNPs are combined with state-of-the-art infrared luminescent nanothermometers (LNTh; Ag2S nanoparticles) in a nanocapsule that simultaneously overcomes these limitations. The novel optomagnetic nanocapsule acts as multimodal contrast agents for different imaging techniques (magnetic resonance, photoacoustic and near-infrared fluorescence imaging, optical and X-ray computed tomography). Most crucially, these nanocapsules provide accurate (0.2 degrees C resolution) and real-time subcutaneous thermal feedback during in vivo MHT, also enabling the attainment of thermal maps of the area of interest. These findings are a milestone on the road toward controlled magnetothermal therapies with minimal side effects., Ministerio de Ciencia, Innovacion y Universidades PID2019-106301RB-I00 PID2019-105195RA-I00, Spanish Ministry of Economy and Competitiveness MAT2017-85617-R SEV-2016-0686, Comunidad de Madrid (RENIM-CM - European Structural and Investment Fund) B2017/BMD-3867 NANOMAGCOST-CM P2018/NMT-4321, Spanish Scientific Network HiperNano RED2018-102626-T, European Commission Horizon 2020 project NanoTBTech 801305, CAM PEJ-2018-AI/IND-11245, Comunidad de Madrid 2019-T1/IND-14014, Juan de la Cierva Formacion scholarship FJC2018-036734-I, European Commission through the European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie Grant 797945, Juan de la Cierva Incorporacion scholarship IJC2019-041915-I, Comunidad de Madrid 2018-T1/IND-1005, AECC (Ideas Semilla 2019 project), European COST Action (MyWave) CA17115, European COST Action (Nano2Clinic) CA17140

A selective and inexpensive chemical paper-based sensor for the detection of gaseous H2S is presented. The triggering of the sensing mechanism is based on an arene-derivative dye which undergoes specific reactions in the presence of H2S, allowing for colorimetric analysis. The dye is embedded into a porous cellulose matrix. We passively exposed the paper strips to H2S generated in itu, while the absorbance was monitored via an optic fiber connected to a spectrophotometer. The kinetics of the emerging absorbance at 534 nm constitute the sensor response and maintain a very stable calibration signal in both concentration and time dimensions for quantitative applications. The time and concentration dependence of the calibration function allows the extraction of unusual analytical information that expands the potential comparability with other sensors in the literature, as the limit of detection admissible within a given exposure time. The use of this specific reaction ensures a very high selectivity against saturated vapors of primary interferents and typical volatile compounds, including alkanethiols. The specific performance of the proposed sensor was explicitly compared with other colorimetric alternatives, including standard lead acetate strips. Additionally, the use of a smartphone camera to follow the color change in the sensing reaction was also tested. With this straightforward method, also affordable for miniature photodiode devices, a limit of detection below the ppm scale was reached in both colorimetric approaches., Operative Programme FEDER-Andalucia (2014-2020, objective 1.2.2., A1122062E0) through project AT17-5549 from the Junta de Andalucía (CECEU), State Research Agency of Spain through projects PID2019-110430GB-C22, PID2019-105195RA-I00 and PCI2020-112241

Early onset Marfan syndrome is the most severe form of Marfan syndrome diagnosed during perinatal period. Early onset Marfan syndrome is associated with high mortality rates, usually within the first 2 years of life. First, we present a case of prenatally diagnosed early onset Marfan syndrome in a dichorionic diamniotic twin pregnancy, where suspicion was raised at 35 weeks of gestation. Ultrasound and fetal magnetic resonance imaging were used to assess prenatal findings in the affected fetus. She presented right diaphragmatic eventration, elongation of humerus and femur and subluxation of the crystalline lens. She died 3 months after birth. Secondly, we present a PubMed-based review of the published articles on early onset Marfan syndrome, with pre- or postnatal suspicion or diagnosis. We found 39 articles published between 1981 and 2017, arising information on 55 cases. Including ours, early onset Marfan syndrome was prenatally diagnosed in 34.54% of the cases. In these cases, the most frequent prenatal findings were cardiomegaly, dilatation of the great vessels and mitral or tricuspid regurgitation. Mortality rate during the first 15 months after birth was 73.68%. In the postnatally diagnosed cases, the most frequent findings were arachnodactyly, dilatation of the great vessels and mitral or tricuspid regurgitation. Mortality rate was 61.11%. Overall genetic confirmation was performed in 67.27% of the cases. Prenatal diagnosis of early onset Marfan syndrome is challenging but of utmost importance, since management should take place in a tertiary care center, by a multidisciplinary team. Differential diagnosis is essential in order to perform an adequate genetic counseling.

We investigate ionization of valeric (n-pentanoic) acid clusters both in the gas phase and on argon and water nanoparticles using mass spectrometry. Compared to the ionization of a single valeric acid molecule, new reaction channels are observed in clusters, mostly attributed to proton transfer between two valeric acid molecules and formation of valeric anhydride. These reactions are also observed when valeric acid molecules are deposited and generate clusters on ArN, and are independent of the ionization method, whether electron ionization or photoionization is used. Valeric acid clusters exhibit a high water affinity, both in neutral clusters and after ionization. When valeric acid is adsorbed on (H2O)M ice nanoparticles, no new specific reactions with water are observed. However, in this case, electron ionization yields mostly protonated water clusters while the photoionization spectrum does not differ significantly from free and ArN-deposited valeric acid clusters. Based on quantum chemical calculations, we extrapolate our results to carboxylic acids with 1-8 carbon atoms. The calculations show that the high affinity to water can be expected in the whole investigated size range while the highest probability of anhydride formation is predicted for n = 3-6. The observed reaction patterns in the ionization of valeric acid are thus prototypical for ionization of clusters of short-chain fatty acids.

We have investigated reactivity of double bond in 2-methyl-2-butene (also trimethylethylene or amylene) in the excited and ionized states. In a combined experimental and theoretical study, we focused on both the intermolecular and intramolecular reactions. In a molecular beam experiment, we have sequentially picked up several amylene molecules on the surface of argon nanoparticles Ar

In this work, we have used thin films of the multiporphyrin, 1,3-di[5-(3-hydroxyphenyl)-10,15,20-(triphenyl)porphyrin]-2-(5-(3-hydroxy-phenyl)-10,15,20-(triphenyl)porphyrin)-2-methylpropane (Triad), its monomer 5-(3-hydroxyphenyl)-10,15,20-triphenylporphyrin (TPPOH) and the simple porphyrin 5,10,15,20-tetraphenyl-porphyrin (TPP), to detect explosive vapors through fluorescence spectroscopy. UV–vis spectroscopy has been used to analyze the degree of molecular aggregation and stability of the porphyrins in the films. The comparison between the three macrocycles has shown that even though the porphyrin Triad can reduce the molecular aggregation and gain stability in films prepared by spin coating in comparison with TPP films, TPPOH forms the least aggregated and most stable films over the porphyrins used in this work. Absorbance response of porphyrins films towards explosive vapors has been analyzed through their exposure to 2,4-dinitrotoluene (DNT) as testing vapor, featuring relatively small and slow spectral changes. Moreover, these absorbance responses have made evident the detrimental effect of molecular aggregation over the sensing capabilities of the porphyrins. However, exposure of porphyrins films to DNT, 1,3-dinitrobenzene (DNB) and 2,4,6-trinitrotoluene (TNT) has resulted in a fast, intense, reversible and repetitive quenching of the fluorescence in all cases, with the monomeric TPPOH exhibiting the best sensing performance among the three compounds. Surprisingly, TPP has shown a relatively large and fast fluorescence response that indicates that aggregation may not affect much the sensing capabilities of porphyrins in terms of fluorescence responses, in contrast to the absorbance responses. This fact has been explained by the lack of emission of H and J-aggregates in the porphyrin films. Finally, although the Triad has featured the slowest quenching response compared to the other two porphyrins, its quenching percentage is in some extent dependent on the type of nitroaromatic, which could be interpreted as a possible ability of Triad to respond more selectively towards explosive vapors.

We describe the synthesis and characterization of a new N-methylpyrrolidine-fused meso-tetracarboxyphenylchlorin with highly emissive features. The synthetic approach to obtain the fluorescent chlorin involves the microwave-assisted synthesis of meso-tetrakis (4-methoxycarbonylphenyl)porphyrin, followed by a 1,3-dipolar cycloaddition reaction of this porphyrin with azomethine ylide and, finally, ester hydrolysis under basic conditions. The incorporation and anchoring of the chlorin to a nanostructured porous TiO2 matrix is achieved and optimized for its use as a fluorescent sensor. In particular, we found an efficient detection of the explosive triacetone triperoxide (TATP) in the gas phase. The optical response after analyte exposure is selective and fast, with response time t50 values of less than 10 min under exposure to TATP saturated vapours.

The purpose of this research was to study how intermittent high intensity exercise affects dynamic postural control in soccer players of the 3rd Spanish Division. Through an intermittent effort test (Yo-Yo Intermittent test 1) the players are subjected to a fatigue situation in order to observe the incidence of dynamic postural control, whose alteration is related to the increased risk of sports injuries. Fatigue is an element that brings with it a series of physiological changes and makes our motor response ineffective due to the diversity of stimuli offered by a sport such as football, and can trigger in an injury, the epidemiology of football shows us the importance of the control of Fatigue and its consequences on the actions of players. Objective. To verify the incidence of fatigue in dynamic postural control. Design. Pre experimental, pre and post treatment of a group. Population. Twelve male players (Age = 4 ± 5.3 years, height = 1.81 ± 0.04 m, weight = 76.8 ± 6.35, fat% = 11.9 ± 0.99%) Method. We performed a pre-test Y Balance Test (YBT), we immediately induce fatigue through Yo-Yo Intermittent test 1, when the player completes the test we obtain lactam sample in blood and perform a post test YBT to see the differences After induced fatigue. Heart rate (HR) was monitored throughout the process to obtain maximum heart rate (HRmax) and the subjective perception of exertion of the players was controlled using Borg scale. Results. After performing a Student's T, we compared the pre and post means in order to verify if there were significant differences. All the scopes declined in the post-test, but significantly the right frontal range (p

The amphiphilic and aggregation properties of fractionated asphaltenes have been studied using Langmuir trough experiments and Brewster angle microscopy (BAM). In particular, two fractions from three different crude oils have been extracted by using two n -pentane:crude oil volume ratios (3:1 and 18:1) in a two-step precipitation procedure. The concentration dependence of the surface properties and the variations in their ability to form true monolayers at the air–water and liquid–liquid interfaces are investigated. The shape of the resulting isotherms are decidedly different. The greater amphiphilic character of the second fraction provides more expanded isotherms and well-behaved hysteresis cycles with more homogeneous domains in comparison with the first one. These results inferred from interface experiments corroborated previous experiments carried out with the pendant drop method. Finally, high contrast BAM images revealed a different aggregation state of the two fractions. The first fraction presents lower surface activity as derived from the air–liquid and liquid–liquid interface experiments and forms aggregates separated by empty spaces at low surfaces pressures according to BAM images. The second fraction show a more homogeneous film structure even at higher surface pressures.

Key Clinical Message Bardet–Biedl syndrome (BBS) is a ciliopathy that is responsible for multiple visceral abnormalities. This disorder is defined by a combination of clinical signs, many of which appear after several years of development. BBS may be suspected antenatally based on routine ultrasound findings of enlarged hyperechogenic kidneys and postaxial polydactyly.

The discrete perturbation approach in its version for soft-core continuous potentials is applied to a family of Mie ( α , γ ) potentials. Within this approach, once a discrete version of the potential is given, only the knowledge of the square-well Helmholtz free-energy perturbation terms are required to obtain the Helmholtz free-energy for the discrete version of the original potential. The free-energy so obtained is analytical and expressed as a function of density, temperature and the intermolecular parameters, and from it all thermodynamic properties can be obtained in a straightforward way. By varying the exponents α and γ some illustrative cases of Mie fluids are considered. Single state pressures and the vapor–liquid phase diagram are obtained and compared with simulation data. The best performance of this equation of state is achieved at supercritical states and when the vapor–liquid phase diagram appears at not so low temperatures. Within this approach the corresponding states principle is analyzed. The methodology presented can be useful to study other families of potentials models for simple and complex fluids.

The macrocycle valinomycin displays an outstanding ability in cation binding and carriage across hydrophobic environments (e.g., cell membranes) and constitutes a central landmark for the design of novel ionophores for the regulation of biochemical processes. Most previous investigations have focused on the capture of metal cations (primarily K+). Here, we address the versatility of valinomycin in the encapsulation of molecular ions of small and moderate size, with NH4+ and H4PO4+ as case studies. A combination of infrared action vibrational spectroscopy and quantum chemical computations of molecular structure and dynamics is employed with the two-fold aim of assessing the dominant H-bonding coordination networks in the complexes and of characterizing the positional and rotational freedom of the guest cations inside the cavity of the macrocycle. Valinomycin binds NH4+ with only moderate distortion of the C3 configuration adopted in the complexes with the metal cations. The ammonium cation occupies the center of the cavity and displays two low-energy coordination arrangements that are dynamically connected through a facile rotation of the cation. The inclusion of the bulkier phosphoric acid cation demands significant stretching of the valinomycin backbone. Interestingly, the H4PO4+ cation achieves ample positional and rotational mobility inside valinomycin. The valinomycin backbone is capable of adopting barrel-like configurations when the cation occupies a region close to the center of the cavity, and funnel-like configurations when it diffuses to positions close to the exit face. This can accommodate the cation in varying coordination arrangements, characterized by different H-bonding between the four POH arms and the ester carbonyl groups of the macrocycle.

10 pags., 8 figs., 2 tabs. -- Published as part of The Journal of Physical Chemistry virtual special issue “F. Javier Aoiz Festschrift”, Rotationally inelastic collisions of O2 with He in the 10−34 K thermal range are investigated by means of an experimental procedure based on supersonic gas jets probed by Raman spectroscopy. The procedure employs a kinetic master equation (MEQ) that describes the time evolution of the rotational populations of O2 along supersonic jets of O2 and He mixtures. The MEQ is expressed in terms of experimental quantities (number density and rotational populations) measured here, and state-to-state rate coefficients for the O2:He inelastic collisions calculated here, plus those for O2:O2 collisions from the literature. An agreement with the experiments is accomplished for temperatures between 10 and 34 K. Within this thermal range, the role of the fine structure due to electron spin in the collision dynamics of O2 is discussed., This work has been supported by the Spanish Ministerio de Economıá y Competitividad (MINECO), grants FIS2017- 84391-C2 and CONSOLIDER-ASTROMOL CSD2009-0038. F.G. thanks the Spanish Regional Government of Andalucıá for a postdoctoral grant (project P07-FQM-2600).

We investigate ionization of valeric (n-pentanoic) acid clusters both in the gas phase and on argon and water nanoparticles using mass spectrometry. Compared to the ionization of a single valeric acid molecule, new reaction channels are observed in clusters, mostly attributed to proton transfer between two valeric acid molecules and formation of valeric anhydride. These reactions are also observed when valeric acid molecules are deposited and generate clusters on Ar

We have sequentially picked up two astrochemically relevant Brønsted acids (methanol and formic acid) on the surface of argon nanoparticles acting as a cold support. Photoionization and electron ionization yield (HCOOH)

Rice (Oryza sativa) stands among the world's most important crop species. Rice is salt sensitive, and the undue accumulation of sodium ions (Na(+)) in shoots has the strongest negative correlation with rice productivity under long-term salinity. The plasma membrane Na(+)/H(+) exchanger protein Salt Overly Sensitive 1 (SOS1) is the sole Na(+) efflux transporter that has been genetically characterized to date. Here, the importance of SOS1-facilitated Na(+) flux in the salt tolerance of rice was analyzed in a reverse-genetics approach. A sos1 loss-of-function mutant displayed exceptional salt sensitivity that was correlated with excessive Na(+) intake and impaired Na(+) loading into the xylem, thus indicating that SOS1 controls net root Na(+) uptake and long-distance Na(+) transport to shoots. The acute Na(+) sensitivity of sos1 plants at low NaCl concentrations allowed analysis of the transcriptional response to sodicity stress without effects of the osmotic stress intrinsic to high-salinity treatments. In contrast with that in the wild type, sos1 mutant roots displayed preferential down-regulation of stress-related genes in response to salt treatment, despite the greater intensity of stress experienced by the mutant. These results suggest there is impaired stress detection or an inability to mount a comprehensive response to salinity in sos1. In summary, the plasma membrane Na(+)/H(+) exchanger SOS1 plays a major role in the salt tolerance of rice by controlling Na(+) homeostasis and possibly contributing to the sensing of sodicity stress.

The antibiotic activity of nonactin is sustained by its ability to transport K+ across lipophilic phases, e.g., the cell membranes. Such a feature can be traced back to a specific ionophoric behavior and to a balanced hydrophobicity modulated by the formation of a cation complex. In this study, the dominant conformations and coordination arrangements in the alkali cation complexes (Na+, K+, Cs+) of nonactin are characterized by means of action vibrational spectroscopy and quantum chemical computations. The low energy conformers of the complexes comprise compact inclusion structures, in which the cation interacts with a varying number of oxygen atoms of the carbonyl and oxolane ring groups of the nonactin macrocycle. The spectroscopy experiments indicate that the three alkali complexes explored are formed in a S4 conformation. This is in contrast with previous crystallography studies, which concluded that the symmetry of the most stable conformer of the complex changes qualitatively with the cation size, from C2 for Na+ to S4 for K+ and Cs+. Computations with different hybrid density functionals lead to contradictory predictions that appear to be quite sensitive to the modelling of the long range interactions in the coordination arrangements. The stabilization of the nonactin-Na+ complex in the C2 or S4 forms emerges as a subtle feature that may be tuned with an appropriate control of the environmental conditions, and constitutes a challenging benchmark to confront novel computational methods for supramolecular systems.

In this work, ultraviolet-visible reflection spectroscopy is proposed as a technique that, in combination with classical surface pressure–area isotherms, allows to study in situ the adsorption of DNA to octadecylamine monolayers. The presence of the polynucleotide molecules at the interface, typically demonstrated by an expansion and a change in the profile of the ODA isotherms, has been confirmed here by a reflection peak at 260 nm. Increasing DNA concentrations in the subphase from 2 to 8 μM is accompanied by an increment in the expansion of the isotherm showing in all cases an abrupt phase transitions at high surface pressures that is also observed in lateral compressibility representations. This phase transition has been attributed to a squeezing out of DNA phenomenon as demonstrated by the normalization of the corresponding reflection spectra. In addition, hysteresis and reversibility in the formation of the monolayer has been identified, making possible the realization of successive compression–decompression cycles without reaching the collapse of the monolayer. It can be inferred that the DNA molecules expelled out of the monolayer at high surface pressures can enter again during the decompression process. Reflection spectroscopy has been also found to be a valuable tool to investigate the dependence of the adsorption process with both time and DNA concentration in the subphase.

Monte–Carlo simulations in the isothermal–isobaric ensemble are employed to characterise the boundaries of isotropic, nematic, smectic and hexatic phases of square-well prolate spherocylinders with a continuous line of interaction sites. Our results show clear first-order phase transitions between the different mesogenic phases. This work considers different issues not previously published for this model that largely comprised the features of real substances without explicit energetical anisotropy parameters. Particular emphasis is given to the enhancement of the stability of the nematic phase in comparison with other prolate fluids of ellipsoidal and spherocylindrical geometry.

An innovative gas sensor based on Forster Resonance Energy Transfer (FRET) has been developed. It comprises the optimization of thin blend films composed of a conjugated semiconducting polymer (host) and a conveniently chosen pH indicator dye (guest) as sensing agent for acid vapors. Spectroscopic characterization of the films demonstrates that upon exposure to HCl gas, quenching of the polymer emission due to energy transfer process is enlarged. Hence, the dramatic spectral change experienced by the dye in acid atmospheres even at low concentration constitute the principle to achieve a quantitative and sensitive detector using the Forster mechanism modulation of the polymer fluorescence as transduction signal. At low and moderate acid concentration, the detector shows relatively fast response and repeatability after consecutive exposure-recovery cycles, whilst these features wipe away at higher acid vapor contents. The concentration dependence of the fluorescence can be described by an appropriate model that takes into account resonant and non-resonant contributions to the observed photoluminescence.

The second virial coefficient and Boyle's temperature of three different anisotropic prolate models with orientational dependent potentials has been determined via numerical integration. Namely, the Gay-Berne, the Gay-Berne-Kihara and the Kihara potentials are treated, the latter used as consistence test. A prototype model with a given geometry with different multipolar anisotropies has been considered. In addition, Boyle temperatures are also evaluated with any desire accuracy. These calculations enlarge the compilation data set of molecular models owning values of the second virial coefficient.

We present here a cheap, fast, and highly selective dosimeter for the colorimetric detection of gaseous phosgene with an ultralow detection limit. The disposable device is based on Harrison’s reagent supported into a porous nanocrystalline TiO2 matrix film. We exposed the films to phosgene streams while the absorbance was monitored by an optic fiber in a gas chamber. The pronounced spectral changes were unaffected by humidity and oxygen and permitted us to use the response rate at 464 nm as a very stable calibration signal for quantitative analysis purposes. The use of a specific sensing reaction guaranteed a very high selectivity of the device even against saturated vapors of primary interferences like halide gases and other oxidizing and volatile agents. With this simple method, whose response is compatible with affordable and efficient miniature LED-photodiode devices, we reach an ultralow limit of detection well below the ppm level.

Aortic arch anomalies are present in 1% to 2% of the general population and are commonly associated with congenital heart disease, chromosomal defects, and tracheaesophageal compression in postnatal life. The sonographically based detection of aortic arch anomalies lies in the 3-vessel and trachea view. Although highly sensitive, this view alone does not allow identification of the aortic arch branching pattern, which prevents an accurate diagnosis. The systematic addition of a subclavian artery view as part of a standardized procedure may be useful in the differential diagnosis of these conditions. We describe the sonographic assessment of fetal aortic arch anomalies by combining 2 fetal transverse views: the 3-vessel and trachea view and the subclavian artery view, which are included in the cardiovascular system sonographic evaluation protocol. We also review the sonographic findings and the clinical implications of fetal aortic arch anomalies.

A double aortic arch is a relatively uncommon anomaly occasionally associated with congenital heart disease or the chromosome 22q11 deletion. We report a case of prenatal diagnosis of a double aortic arch in which the sonographic features in the 3-vessel and trachea view are highlighted. A PubMed-based search was made to retrieve all cases of prenatal diagnosis of double aortic arch. A total of 13 articles and 35 cases were found. The average gestational age at diagnosis was 29 weeks. Six cases had associated cardiac anomalies. Only 1 case had the 22q11 deletion, showing extracardiac anomalies without cardiac defect. The postnatal evolution was characterized by symptoms of tracheoesophageal compression in 72.4% of the cases. Detection of a double aortic arch should be followed by a thorough fetal scan and echocardiography, and a chromosomal study should be considered when the sonographic findings are consistent with the 22q11 deletion.

The understanding of supramolecular recognition in room-temperature ionic liquids (RTILs) is key to develop the full potential of these materials. In this work, we provide insights into the selectivity of the binding of alkali metal cations by standard cyclodextrin and calixarene macrocycles in RTILs. A direct laser desorption/ionization mass spectrometry approach is employed to determine the relative abundances of the inclusion complexes formed through competitive binding in RTIL solutions. The results are compared with the binding selectivities measured under solvent-free conditions and in water/methanol solutions. Cyclodextrins and calixarenes in which the peripheral OH groups are substituted by bulkier side groups preferentially bind to Cs(+) . Such specific ionophoric behavior is substantially enhanced by solvation effects in the RTIL. This finding is rationalized with the aid of quantum mechanical calculations, in terms of the conformational features and steric interactions that drive the solvation of the inclusion complexes by the bulky RTIL counterions.

The exact second virial coefficient ( B 2 ) for anisotropic fluids is evaluated in a compact and exact form. Explicitly, the B 2 expressions for spherical D -dimensional square well fluids with an embedded point dipole are given in terms of simple special functions for the whole range of dipole moment strengths and potential ranges. An alternative equation for the B 2 value of three-dimensional Stockmayer model is also reported for comparison purposes. Additionally, some aspects of the second virial coefficient for non-spherical square-well model are discussed in relation with the formation of ordered fluids. In addition, Boyle temperatures are also evaluated with any desire accuracy. These calculations enlarge the set of molecular models owning an analytical expression for the second virial coefficient.

Objectives - To evaluate the reproducibility and feasibility of the new cardiovascular system sonographic evaluation algorithm for studying the extended fetal cardiovascular system, including the portal, thymic, and supra-aortic areas, in the second trimester of pregnancy (19-22 weeks). Methods - We performed a cross-sectional study of pregnant women with healthy fetuses (singleton and twin pregnancies) attending our center from March to August 2011. The extended fetal cardiovascular system was evaluated by following the new algorithm, a sequential acquisition of axial views comprising the following (caudal to cranial): I, portal sinus; II, ductus venosus; III, hepatic veins; IV, 4-chamber view; V, left ventricular outflow tract; VI, right ventricular outflow tract; VII, 3-vessel and trachea view; VIII, thy-box; and IX, subclavian arteries. Interobserver agreement on the feasibility and exploration time was estimated in a subgroup of patients. The feasibility and exploration time were determined for the main cohort. Maternal, fetal, and sonographic factors affecting both features were evaluated. Results - Interobserver agreement was excellent for all views except view VIII; the difference in the mean exploration time between observers was 1.5 minutes (95% confidence interval, 0.7-2.1 minutes; P < .05). In 184 fetuses (mean gestational age ± SD, 20 ± 0.6 weeks), the feasibility of all views was close to 99% except view VIII (88.7%). The complete feasibility of the algorithm was 81.5%. The mean exploration time was 5.6 ± 4.2 minutes. Only the occiput anterior fetal position was associated with a lower frequency of visualization and a longer exploration time (P < .05). Conclusions - The cardiovascular system sonographic evaluation algorithm is a reproducible and feasible approach for exploration of the extended fetal cardiovascular system in a second-trimester scan. It can be used to explore these areas in normal and abnormal conditions and provides an integrated image of extended fetal cardiovascular anatomy.

Objectives - The purpose of this study was to estimate reference ranges for the pulsatility index (PI) of the fetal aortic isthmus in uncomplicated singleton and twin pregnancies during the second half of pregnancy. Methods - We conducted a cross-sectional observational study involving 543 healthy fetuses: 361 singleton pregnancies and 182 twin pregnancies between 19 and 36 weeks' gestation. The aortic isthmus PI was measured in 2 sonographic planes: the longitudinal aortic arch view and the 3-vessel and trachea view. We evaluated the reproducibility of aortic isthmus PI measurements between these planes by calculating intraclass correlation coefficients and limits of agreement. Scans were performed by 2 physicians, and intraobserver agreement was also measured. Regression analysis was used to estimate gestational age reference values for the aortic isthmus PI. Results - The aortic isthmus PI was significantly correlated with gestational age in singletons and twins during the second half of pregnancy (P < .01). We did not find significant differences between reference ranges in singletons and twins or between the sonographic views. Conclusions - This study offers reference ranges for the aortic isthmus PI during the second half of gestation in singleton and twin pregnancies. Mean aortic isthmus PI values were similar in both types of gestations as well as both sonographic views. The aortic isthmus PI may be reliably obtained from either sonographic view.

Congenital double aortic arch (DAA) is an uncommon vascular anomaly; however, its prenatal detection is associated with congenital heart defects and chromosomal abnormalities, including 22q11 deletion. We present a case of DAA diagnosed prenatally. DAA can be diagnosed by prenatal ultrasound in the transverse three vessel-trachea view, which shows a trident image formed by a complete vascular ring and the ductus arteriosus. Postnatal magnetic resonance images in this view correlate well with prenatal ultrasound images and help in confirmation of diagnosis, evaluation of the risk of airway or esophageal compression, and planning of surgery.

We present here a highly sensitive optical device for sensing of acid vapors based on the specific properties of thin films of a light emitting conjugated polymer. In these films, the emission quenching of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] in acid environments can be monitorized by the changes in the fluorescence spectra. Both fluorescence and amplified spontaneous emission (ASE) have been used as transduction signals. Working with fluorescence, the sensor shows relatively fast response and good repeatability after consecutive exposure-recovery cycles to formic acid vapors that was selected as a model analyte. Also, the response is concentration-dependent in the 0–6000 ppm range with adequate fitting to standard models. When the ASE signal is used, a strong quenching is observed for very low acid concentrations, reaching a limit of detection in the sub-ppm range (40 ppb) which is to the best of our knowledge the lowest value found in the literature for formic acid detection by optical sensors.