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Fabry disease (FD) is a rare X-linked lysosomal storage disorder caused by a deficiency in α-galactosidase A leading to the accumulation of globotriaosylceramide (Gb 3 ) and subsequent increase in globotriaosylsphingosine (lyso-Gb 3 ) in different cells and organs, including the gastrointestinal (GI) tract. GI symptoms represent some of the earliest manifestations of FD and significantly impact quality of life. The origin of these symptoms is complex, and the exact mechanisms remain poorly understood. Here, we sought to determine whether lyso-Gb 3 contributes to the pathophysiology of GI symptoms associated with FD by examining its effects on mouse colonic ion transport and motility ex vivo using Ussing chambers and organ baths, respectively. Lyso-Gb 3 significantly increased colonic baseline short-circuit current ( I sc ). This increase in I sc was insensitive to inhibition of the cystic fibrosis transmembrane conductance regulator and Na-K-Cl cotransporter 1, suggesting that the increase in I sc is Cl - ion independent. This response was also insensitive to inhibition by the neurotoxin, tetrodotoxin. In addition, pretreatment with lyso-Gb 3 did not significantly influence subsequent responses to either veratridine or capsaicin implying that the response to lyso-Gb 3 does not involve the enteric nervous system. In terms of colonic motility, lyso-Gb 3 did not significantly influence colonic tone, spontaneous contractility, or cholinergic-induced contractions. These data suggest that lyso-Gb 3 significantly influences ion transport in mouse colon, but that accumulation of Gb 3 may be a prerequisite for the more pronounced disturbances in GI physiology characteristic of FD. NEW & NOTEWORTHY Fabry disease-associated lyso-Gb 3 significantly influences mouse colonic ion transport in a Cl - ion-independent manner.

Germanium is a promising basis for nanomaterials due to its low toxicity and valuable optical and electronic properties. However, germanium nanomaterials have seen little research compared to other group 14 elements due to unpredictable chemical behavior and high costs. Here, we report the dehydrocoupling of o-tolylgermanium trihydride to amorphous nanoparticles. The reaction is facilitated through reflux at 162 °C and can be accelerated with an amine base catalyst. Through cleavage of both H 2 and toluene, new Ge-Ge bonds form. This results in nanoparticles consisting of crosslinked germanium with o-tolyl termination. The particles are 2-6 nm in size and have masses above approximately 3500 Da. The organic substituents are promising for further functionalization. Combined with strong absorption up to 600 nm and moderate solubility and air stability, there are numerous possibilities for future applications., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The structural features of cobalt-based oxygen evolution catalysts are elucidated by combining high-field MAS NMR spectroscopy and DFT calculations. The superior photocatalytic activity of the heterogeneous system over its homogeneous counterpart is rationalised by the structural features. The higher activity is caused by a more favourable electron-withdrawing character of the framework.

Fabry disease (FD) is an X-linked metabolic disease caused by a deficiency in α-galactosidase A (α-Gal A) activity. This causes accumulation of glycosphingolipids, especially globotriaosylceramide (Gb3), in different cells and organs. Neuropathic pain and gastrointestinal (GI) symptoms, such as abdominal pain, nausea, diarrhea, constipation, and early satiety, are the most frequent symptoms reported by FD patients and severely affect their quality of life. It is generally accepted that Gb3 and lyso-Gb3 are involved in the symptoms; nevertheless, the origin of these symptoms is complex and multifactorial, and the exact mechanisms of pathogenesis are still poorly understood. Here, we used a murine model of FD, the male α-Gal A (-/0) mouse, to characterize functionality, behavior, and microbiota in an attempt to elucidate the microbiota-gut-brain axis at three different ages. We provided evidence of a diarrhea-like phenotype and visceral hypersensitivity in our FD model together with reduced locomotor activity and anxiety-like behavior. We also showed for the first time that symptomology was associated with early compositional and functional dysbiosis of the gut microbiota, paralleled by alterations in fecal short-chain fatty acid levels, which partly persisted with advancing age. Interestingly, most of the dysbiotic features suggested a disruption of gut homeostasis, possibly contributing to accelerated intestinal transit, visceral hypersensitivity, and impaired communication along the gut-brain axis.

The physiological consequences of stress often manifest in the gastrointestinal tract. Traumatic or chronic stress is associated with widespread maladaptive changes throughout the gut, although comparatively little is known about the effects of acute stress. Furthermore, these stress-induced changes in the gut may increase susceptibility to gastrointestinal disorders and infection, and impact critical features of the neural and behavioural consequences of the stress response by impairing gut-brain axis communication. Understanding the mechanisms behind changes in enteric nervous system circuitry, visceral sensitivity, gut barrier function, permeability, and the gut microbiota following stress is an important research objective with pathophysiological implications in both neurogastroenterology and psychiatry. Moreover, the gut microbiota has emerged as a key aspect of physiology sensitive to the effects of stress. In this review, we focus on different aspects of the gastrointestinal tract including gut barrier function as well as the immune, humoral and neuronal elements involved in gut-brain communication. Furthermore, we discuss the evidence for a role of stress in gastrointestinal disorders. Existing gaps in the current literature are highlighted, and possible avenues for future research with an integrated physiological perspective have been suggested. A more complete understanding of the spatial and temporal dynamics of the integrated host and microbial response to different kinds of stressors in the gastrointestinal tract will enable full exploitation of the diagnostic and therapeutic potential in the fast-evolving field of host-microbiome interactions., (© 2023 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Oxytocin is a peptide-hormone extensively studied for its multifaceted biological functions and has recently gained attention for its role in eating behavior, through its action as an anorexigenic neuropeptide. Moreover, the gut microbiota is involved in oxytocinergic signaling through the brain-gut axis, specifically in the regulation of social behavior. The gut microbiota is also implicated in appetite regulation and is postulated to play a role in central regulation of hedonic eating. In this review, we provide an overview on oxytocin and its individual links with the microbiome, the homeostatic and non-homeostatic regulation of eating behavior as well as social behavior and stress., (© 2023 The Authors. Journal of Neuroendocrinology published by John Wiley & Sons Ltd on behalf of British Society for Neuroendocrinology.)

Amphiphilic copolymer self-assembly is a straightforward approach to obtain responsive micelles, nanoparticles, and vesicles that are particularly attractive for biomedicine, i.e., for the delivery of functional molecules. Here, amphiphilic copolymers of hydrophobic polysiloxane methacrylate and hydrophilic oligo (ethylene glycol) methyl ether methacrylate with different lengths of oxyethylenic side chains were synthesized via controlled RAFT radical polymerization and characterized both thermally and in solution. In particular, the thermoresponsive and self-assembling behavior of the water-soluble copolymers in water was investigated via complementary techniques such as light transmittance, dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS) measurements. All the copolymers synthesized were thermoresponsive, displaying a cloud point temperature ( T cp ) strongly dependent on macromolecular parameters such as the length of the oligo(ethylene glycol) side chains and the content of the SiMA counits, as well as the concentration of the copolymer in water, which is consistent with a lower critical solution temperature (LCST)-type behavior. SAXS analysis revealed that the copolymers formed nanostructures in water below T cp , whose dimension and shape depended on the content of the hydrophobic components in the copolymer. The hydrodynamic diameter ( D h ) determined by DLS increased with the amount of SiMA and the associated morphology at higher SiMA contents was found to be pearl-necklace-micelle-like, composed of connected hydrophobic cores. These novel amphiphilic copolymers were able to modulate thermoresponsiveness in water in a wide range of temperatures, including the physiological temperature, as well as the dimension and shape of their nanostructured assemblies, simply by varying their chemical composition and the length of the hydrophilic side chains.

The goal of reconciling all packaging requirements, e.g., mechanical resistance, transparency, flexibility, and gas barrier properties, is immensely challenging for packaging materials. Particularly, the combination of flexibility and good gas barrier properties poses a serious problem, especially when barrier requirements can only be met by lamination with a metal foil, metalization, or vapor-deposited ceramic layers, as all of these tend to be nonstretchable. In this work, we produced a stretchable nanocomposite barrier composed of one-dimensional (1D) crystalline (Bragg stack) barrier films composed of alternating layers of poly(ethylene glycol) (PEG) and synthetic sodium fluorohectorite (Hec) nanosheets. By sandwiching the Bragg stack type film between two plasticized poly(vinyl alcohol) (PVOH) layers, a waterborne laminate was obtained that outperforms commercial polymer materials in terms of water vapor permeability (WVP = 2.8 g mm m -2 day -1 bar -1 at 23 °C and 85% relative humidity), which is remarkable for an entirely water-soluble film. Moreover, no deterioration of barrier performance up to 10% elongation was observed, rendering the transparent self-standing laminate promising for thermoformed blister packaging, shrink wrap, or vacuum packaging. Besides the low WVP, the scalable and green processing method makes this technology auspicious for real-world applications.

Chronic psychological stress affects brain regions involved in memory such as the hippocampus and accelerates age-related cognitive decline, including in Alzheimer's disease and vascular dementia. However, little is known about how chronic stress impacts hippocampal vascular function that is critically involved in maintaining neurocognitive health that could contribute to stress-related memory dysfunction. Here, we used a novel experimental rat model that mimics the neuroendocrine and cardiovascular aspects of chronic stress to determine how the neuroendocrine components of the stress response affect hippocampal function. We studied both male and female rats to determine potential sex differences in the susceptibility of the hippocampus and its vasculature to neuroendocrine stress-induced dysfunction. We show that activation of neuroendocrine stress pathways impaired the vasoreactivity of hippocampal arterioles to mediators involved in coupling neuronal activity with local blood flow that was associated with impaired memory function. Interestingly, we found more hippocampal arteriolar dysfunction and scarcer hippocampal microvasculature in male compared to female rats that was associated with greater memory impairment, suggesting the male sex may be at increased risk of neuroendocrine-derived hippocampal dysfunction during chronic stress. Overall, this study revealed the therapeutic potential of targeting hippocampal arterioles to prevent or slow memory decline in the setting of prolonged and/or unavoidable stress., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

The gut microbiome can produce metabolic products that exert diverse activities, including effects on the host. Short chain fatty acids and amino acid derivatives have been the focus of many studies, but given the high microbial density in the gastrointestinal tract, other bacterial products such as those released as part of quorum sensing are likely to play an important role for health and disease. In this review, we provide of an overview on quorum sensing (QS) in the gastrointestinal tract and summarise what is known regarding the role of QS molecules such as auto-inducing peptides (AIP) and acyl-homoserine lactones (AHL) from commensal, probiotic, and pathogenic bacteria in intestinal health and disease. QS regulates the expression of numerous genes including biofilm formation, bacteriocin and toxin secretion, and metabolism. QS has also been shown to play an important role in the bacteria-host interaction. We conclude that the mechanisms of action of QS at the intestinal neuro-immune interface need to be further investigated.

Liquid-phase exfoliation (LPE) is a widely used and promising method for the production of 2D nanomaterials because it can be scaled up relatively easily. Nevertheless, the yields achieved by this process are still low, ranging between 2% and 5%, which makes the large-scale production of these materials difficult. In this report, we investigate the cause of these low yields by examining the sonication-assisted LPE of graphene, boron nitride nanosheets (BNNSs), and molybdenum disulfide nanosheets (MoS 2 NS). Our results show that the low yields are caused by an equilibrium that is formed between the exfoliated nanosheets and the flocculated ones during the sonication process. This study provides an understanding of this behaviour, which prevents further exfoliation of nanosheets. By avoiding this equilibrium, we were able to increase the total yields of graphene, BNNSs, and MoS 2 NS up to 14%, 44%, and 29%, respectively. Here, we demonstrate a modified LPE process that leads to the high-yield production of 2D nanomaterials.

Despite recently established contributions of the intestinal microbiome to human health and disease, our understanding of bacteria-host communication pathways with regard to the gut-brain axis remains limited. Here we provide evidence that intestinal neurons are able to "sense" bacteria independently of the host immune system. Using supernatants from cultures of the opportunistic pathogen Staphylococcus aureus ( S . aureus ) we demonstrate the release of mediators with neuromodulatory properties at high population density. These mediators induced a biphasic response in extrinsic sensory afferent nerves, increased membrane permeability in cultured sensory neurons, and altered intestinal motility and secretion. Genetic manipulation of S . aureus revealed two key quorum sensing-regulated classes of pore forming toxins that mediate excitation and inhibition of extrinsic sensory nerves, respectively. As such, bacterial mediators have the potential to directly modulate gut-brain communication to influence intestinal symptoms and reflex function in vivo , contributing to homeostatic, behavioral, and sensory consequences of infection., Competing Interests: The authors declare no competing interest., (© 2020 The Authors.)

The optimization of the thermal treatment of cationic starch in the paper industry offers the opportunity to reduce the energy consumption of this process . Four different industrially relevant cationic starches, varying in source, cationization method and degree of substitution were treated by a steam-jet cooking procedure, comparable to industrially employed starch cooking processes. The influence of the starch properties and cooking parameters on the adsorption behavior of the starches on cellulosic pulp was investigated. The adsorbed amount was affected by the cooking temperature and the type of starch. For some starch grades, a cooking temperature of 115 °C can be employed to achieve sufficient starch retention on the pulp fibers. The energy consumption could further be reduced by cooking at higher starch concentrations without loss of adsorption efficiency., Competing Interests: The authors declare no conflict of interest.

The rational control of the electronic and optical properties of small functionalized diamond-like molecules, the diamondoids, is the focus of this work. Specifically, we investigate the single- and double- functionalization of the lower diamondoids, adamantane, diamantane, and triamantane with -NH 2 and -SH groups and extend the study to N-heterocyclic carbene (NHC) functionalization. On the basis of electronic structure calculations, we predict a significant change in the optical properties of these functionalized diamondoids. Our computations reveal that -NH 2 functionalized diamondoids show UV photoluminescence similar to ideal diamondoids while -SH substituted diamondoids hinder the UV photoluminescence due to the labile nature of the S-H bond in the first excited state. This study also unveils that the UV photoluminescence nature of -NH 2 diamondoids is quenched upon additional functionalization with the -SH group. The double-functionalized derivative can, thus, serve as a sensitive probe for biomolecule binding and sensing environmental changes. The preserved intrinsic properties of the NHC and the ideal diamondoid in NHC-functionalized-diamondoids suggests its utilization in diamondoid-based self-assembled monolayers (SAM), whose UV-photoluminescent signal would be determined entirely by the functionalized diamondoids. Our study aims to pave the path for tuning the properties of diamondoids through a selective choice of the type and number of functional groups. This will aid the realization of optoelectronic devices involving, for example, large-area SAM layers or diamondoid-functionalized electrodes.

Ionization in the condensed phase and molecular clusters leads to a complicated chain of processes with coupled electron-nuclear dynamics. It is difficult to describe such dynamics with conventional nonadiabatic molecular dynamics schemes since the number of states swiftly increases as the molecular system grows. It is therefore attractive to use a direct electron and nuclear propagation such as the real-time time-dependent density functional theory (RT-TDDFT). Here we report a RT-TDDFT benchmark study on simulations of singly and doubly ionized states of a water monomer and dimer as a prototype for more complex processes in a condensed phase. We employed the RT-TDDFT based Ehrenfest molecular dynamics with a generalized gradient approximate (GGA) functional and compared it with wave-function-based surface hopping (SH) simulations. We found that the initial dynamics of a singly HOMO ionized water dimer is similar for both the RT-TDDFT/GGA and the SH simulations but leads to completely different reaction channels on a longer time scale. This failure is attributed to the self-interaction error in the GGA functionals and it can be avoided by using hybrid functionals with large fraction of exact exchange (represented here by the BHandHLYP functional). The simulations of doubly ionized states are reasonably described already at the GGA level. This suggests that the RT-TDDFT/GGA method could describe processes following the autoionization processes such as Auger emission, while its applicability to more complex processes such as intermolecular Coulombic decay remains limited.

We present an ab initio parametrization scheme for explicitly dipole-polarizable force fields for the simulation of molecular liquids. The scheme allows for, in principle, arbitrarily coarse-grained representations. All parameters in the force field are derived from first-principles, based on simple physical arguments. Only one fit parameter enters the parametrization, a global scaling factor for the size of the particles, which is adjusted to reproduce the experimental mass density. As important examples and for the first time, polarizable coarse-grained force fields are derived for 1-alkyl-3-methylimidazolium cations with varying alkyl-chain lengths (alkyl = ethyl, butyl, hexyl) and hexafluorophosphate and tetrafluoroborate anions. Our findings are in good agreement with experimental results and results of further atomistic simulations. Hence, the force fields can be faithfully used where polarizability is expected to play a significant role, such as simulations of energy storage devices.

We present a coarse-grained polarizable molecular dynamics force field for the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF 6 ]). For the treatment of electronic polarizability, we employ the Drude model. Our results show that the new explicitly polarizable force field reproduces important static and dynamic properties such as mass density, enthalpy of vaporization, diffusion coefficients, or electrical conductivity in the relevant temperature range. In situations where an explicit treatment of electronic polarizability might be crucial, we expect the force field to be an improvement over non-polarizable models, while still profiting from the reduction of computational cost due to the coarse-grained representation.

Using quantum mechanical calculations within density functional theory, we provide a comprehensive analysis of infrared-active excitation of water molecules confined in nanocages of a beryl crystal lattice. We calculate infrared-active modes including the translational, librational, and mixed-type resonances of regular and heavy water molecules. The results are compared to the experimental spectra measured for the two principal polarizations of the electric field: parallel and perpendicular to the crystallographic c-axis. Good agreement is achieved between calculated and measured isotopic shifts of the normal modes. We analyze the vibrational modes in connection with the structural characteristics and arrangements of water molecules within the beryl crystal. Specific atomic displacements are assigned to each experimentally detected vibrational mode resolving the properties of nano-confined water on scales not accessible by experiments. Our results elucidate the applicability and efficiency of a combined experimental and computational approach for describing and an in-depth understanding of nano-confined water, and pave the way for future studies of more complex systems.

Core-level spectra of liquids can be difficult to interpret due to the presence of a range of local environments. We present computational methods for investigating core-level spectra based on the idea that both local structural parameters and the x-ray spectra behave as functions of the local atomic configuration around the absorbing site. We identify correlations between structural parameters and spectral intensities in defined regions of interest, using the oxygen K-edge excitation spectrum of liquid water as a test case. Our results show that this kind of analysis can find the main structure-spectral relationships of ice, liquid water, and supercritical water.

NeuroGUT is a EU-funded initial training network (ITN) of 14 research projects in neurogastroenterology that have employed an equal number of early-stage researchers. Neurogut trainees have-among other activities-attended an international conference on irritable bowel syndrome (IBS) in Bologna in 2016 and were asked to critically review and evaluate the current knowledge on IBS for their respective research activities, and to state what they were missing. Most appreciated were the topics brain imaging of gut activity, the role of the gut microbiota, the pharmacology of gut functions, the IBS-IBD interrelation, the new Rome IV criteria, the role of gas, and the placebo response in functional disorders. Missed were more detailed coverage of high-resolution manometry, functional brain imaging, advanced "systems medicine" approaches and bioinformatics technology, better sub-classification of IBS patients, and the development of disease biomarkers, extended at the molecular (genetic/epigenetic, proteonomic) level. They summarize that despite excellent specialized research, there is a gap open that should be filled with systems medicine. For this, it would be necessary that medical research learns even more from the data sciences and other basic disciplines, for example, information technology and system biology, and also welcomes a change in paradigm that enhances open sharing of data, information, and resources., (© 2016 John Wiley & Sons Ltd.)

The first hybrid crown ether with two adjacent disilane fragments was synthesized through reaction of O(Si 2 Me 4 Cl) 2 (3) with O(C 2 H 4 OH) 2 . By means of DFT calculations, the complexation ability of 1,2,4,5-tetrasila[12]crown-4 (7) towards Li + was determined to be considerably higher compared to [12]crown-4.

Ectoine is an important osmolyte, which allows microorganisms to survive in extreme environmental salinity. The hygroscopic effects of ectoine in pure water can be explained by a strong water binding behavior whereas a study on the effects of ectoine in salty solution is yet missing. We provide Raman spectroscopic evidence that the influence of ectoine and NaCl are opposing and completely independent of each other. The effect can be explained by the formation of strongly hydrogen-bonded water molecules around ectoine which compensate the influence of the salt on the water dynamics. The mechanism is corroborated by first principles calculations and broadens our understanding of zwitterionic osmolytes in aqueous solution. Our findings allow us to provide a possible explanation for the relatively high osmolyte concentrations in halotolerant bacteria.

Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-5-protein (G5P) to a single-stranded DNA (dT25). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonucleotide, which has important consequences for osmotic regulation mechanisms.

Self-assembled phases based on monoglycerides are promising candidates for drug delivery systems. Alterations of these phases need to be performed by addition of substances which are biocompatible. Inverse bicontinuous cubic phases are altered by the addition of five amino acids, namely, glycine, phenylalanine, alanine, glutamine, and tryptophan. These natural molecules have a diversity of side chains which predicts their polarity and subsequently their interaction with the interfacial region. Whereas polar amino acids cause a slight shrinking of the fully hydrated phase, amino acids with a nonpolar side chain expand it. Tryptophan is also able to provoke a growth of inverse hexagonal, micellar cubic, and micellar structures. Amino acid concentrations in the aqueous phase, even above the amino acid's solubility, further affect all aforementioned structures and cause a significant enlargement of up to 26%. Besides the amino acids' impact on the structural sizes, they also affect the phase transition temperatures.

Alkali metals can react explosively with water and it is textbook knowledge that this vigorous behaviour results from heat release, steam formation and ignition of the hydrogen gas that is produced. Here we suggest that the initial process enabling the alkali metal explosion in water is, however, of a completely different nature. High-speed camera imaging of liquid drops of a sodium/potassium alloy in water reveals submillisecond formation of metal spikes that protrude from the surface of the drop. Molecular dynamics simulations demonstrate that on immersion in water there is an almost immediate release of electrons from the metal surface. The system thus quickly reaches the Rayleigh instability limit, which leads to a 'coulomb explosion' of the alkali metal drop. Consequently, a new metal surface in contact with water is formed, which explains why the reaction does not become self-quenched by its products, but can rather lead to explosive behaviour.

The optical spectrum of the hydrated (aqueous) electron, e(aq)(–), is the primary observable by means of which this species is detected, monitored, and studied. In theoretical calculations, this spectrum has most often been simulated using one-electron models. Here, we present ab initio simulations of that spectrum in both bulk water and, for the first time, at the water/vapor interface, using density functional theory and its time-dependent variant. Our results indicate that this approach provides a reliable description, and quantitative agreement with the experimental spectrum for the bulk species is obtained using a “tuned” long-range corrected functional. The spectrum of the interfacial electron is found to be very similar to the bulk spectrum.

It is generally assumed that the hydrated electron occupies a quasi-spherical cavity surrounded by only a few water molecules in its equilibrated state. However, in the very moment of its generation, before water has had time to respond to the extra charge, it is expected to be significantly larger in size. According to a particle-in-a-box picture, the frequency of its absorption spectrum is a sensitive measure of the initial size of the electronic wavefunction. Here, using transient terahertz spectroscopy, we show that the excess electron initially absorbs in the far-infrared at a frequency for which accompanying ab initio molecular dynamics simulations estimate an initial delocalization length of ≈ 40 Å. The electron subsequently shrinks due to solvation and thereby leaves the terahertz observation window very quickly, within ≈ 200 fs.

Introduction: Full-face-masks (FFM) prevent the diver's face from cold and can support nasal breathing underwater. The aim of the study was to evaluate the effect of the use of FFMs on lung function and wellbeing., Methods: Twenty-one, healthy, non-asthmatic divers performed two cold-water dives (4⁰C, 25 min, 10 metres' depth) - one with a FFM and the other with a standard scuba regulator (SSR). Spirometry was performed before and after each dive and well-being and cold sensation were assessed after the dives., Results: Significant decreases in forced vital capacity (FVC), forced expiratory volume in one second (FEV₁) and midexpiratory flow at 75% of FVC (MEF₇₅) occurred after both FFM and SSR dives. Changes in FVC and FEV₁ did not differ significantly between FFM and SSR dives. However, the mid-expiratory flows measured at 50% and 25% of FVC (MEF₅₀ and MEF₂₅) were significantly lower 10 minutes after the FFM dive compared to 10 minutes after the SSR dive. The wellbeing and cold sensation of the divers were significantly improved with FFM dives compared to SSR dives., Conclusions: Cold-water dives during wintertime can be associated with airway narrowing. During cold-water dives, the use of a FFM appears to reduce the cold sensation and enhance the well-being of the divers. However, a FFM does not appear to prevent airway narrowing in healthy, non-asthmatic subjects.

The hydrated electron is a crucial species in radiative processes, and it has been speculated that its behavior at the water surface could lead to specific interfacial chemical properties. Here, we address fundamental questions concerning the structure and energetics of an electron at the surface of water. We use the method of ab initio molecular dynamics, which was shown to provide a faithful description of solvated electrons in large water clusters and in bulk water. The present results clearly demonstrate that the surface electron is mostly buried in the interfacial water layer, with only about 10 % of its density protruding into the vapor phase. Consequently, it has a structure that is very similar to that of an electron solvated in the aqueous bulk. This points to a general feature of charges at the surface of water, namely, that they do not behave as half-dehydrated but rather as almost fully hydrated species.

The structure of the hydrated electron, which is a key species in radiative processes in water, has remained elusive. The traditional cavity model has been questioned recently, but the newly suggested picture of an electron delocalized over a region of enhanced water density is controversial. Here, we present results from ab initio molecular dynamics simulations, where not only the excess electron but also the valence electrons of the surrounding water molecules are described quantum mechanically. Unlike in previous one-electron pseudopotential calculations, many-electron interactions are explicitly accounted for. The present approach allows for partitioning of the electron solvated in liquid water into contributions from an inner cavity, neighboring water molecules, and a diffuse tail. We demonstrate that all three of these contributions are sizable and, consequently, important, which underlines the complex nature of the hydrated electron and warns against oversimplified interpretations based on pseudopotential models.

Understanding the properties of hydrated electrons, which were first observed using pulse radiolysis of water in 1962, is crucial because they are key species in many radiation chemistry processes. Although time-resolved spectroscopic studies and molecular simulations have shown that an electron in water (prepared, for example, by water photoionization) relaxes quickly to a localized, cavity-like structure ∼2.5 Å in radius, this picture has recently been questioned. In another experimental approach, negatively charged water clusters of increasing size were studied with photoelectron and IR spectroscopies. Although small water clusters can bind an excess electron, their character is very different from bulk hydrated species. As data on electron binding in liquid water have become directly accessible experimentally, the cluster-to-bulk extrapolations have become a topic of lively debate. Quantum electronic structure calculations addressing experimental measurables have, until recently, been largely limited to small clusters; extended systems were approached mainly with pseudopotential calculations combining a classical description of water with a quantum mechanical treatment of the excess electron. In this Account, we discuss our investigations of electrons solvated in water by means of ab initio molecular dynamics simulations. This approach, applied to a model system of a negatively charged cluster of 32 water molecules, allows us to characterize structural, dynamical, and reactive aspects of the hydrated electron using all of the system's valence electrons. We show that under ambient conditions, the electron localizes into a cavity close to the surface of the liquid cluster. This cavity is, however, more flexible and accessible to water molecules than an analogous area around negatively charged ions. The dynamical process of electron attachment to a neutral water cluster is strongly temperature dependent. Under ambient conditions, the electron relaxes in the liquid cluster and becomes indistinguishable from an equilibrated, solvated electron on a picosecond time scale. In contrast, for solid, cryogenic systems, the electron only partially localizes outside of the cluster, being trapped in a metastable, weakly bound "cushion-like" state. Strongly bound states under cryogenic conditions could only be prepared by cooling equilibrated, liquid, negatively charged clusters. These calculations allow us to rationalize how different isomers of electrons in cryogenic clusters can be observed experimentally. Our results also bring into question the direct extrapolation of properties of cryogenic, negatively charged water clusters to those of electrons in the bulk liquid. Ab initio molecular dynamics represents a unique computational tool for investigating the reactivity of the solvated electron in water. As a prototype, the electron-proton reaction was followed in the 32-water cluster. In accord with experiment, the molecular mechanism is a proton transfer process that is not diffusion limited, but rather controlled by a proton-induced deformation of the excess electron's solvent shell. We demonstrate the necessary ingredients of a successful density functional methodology for the hydrated electron that avoids potential pitfalls, such as self-interaction error, insufficient basis set, or lack of dispersion interactions. We also benchmark the density functional theory methods and outline the path to faithful ab initio simulations of dynamics and reactivity of electrons solvated in extended aqueous systems.

Room-temperature ionic liquids containing the triply charged tricyanomelaminate (tcmel) ion [C(3)N(6)(CN)(3)](3-) were synthesized. The 1-methyl-3-methylimidazolium (MMIm), 1-ethyl-3-methylimidazolium (EMIm), and 1-butyl-3-methylimidazolium (BMIm) salts of the tricyanomelaminate ion have glass transition temperatures (-6, -20, and -30 °C) similar to those found for the analogous monomeric dicyanoamide salts. They are thermally stable up to over 200 °C and dissolve in polar organic solvents. Addition of B(C(6)F(5))(3) to M(3) [tcmel] (M=Na, MMIm, EMIm, BMIm) yields salts containing the very voluminous adduct ion [C(3)N(6) {CN·B(C(6)F(5))(3)}(3)](3-) (tcmel_3B). The solid-state structure of [MMIm](3-) [tcmel] shows only long cation···anion contacts but in large number, while the solid-state structure of [Na(THF)(3)](3-) [tcmel_3B]·1.76 THF displays strong interactions of the sodium cation with the amido nitrogen atoms of the anion. Hence this adduct anion cannot be regarded as a weakly coordinating anion. A similar situation is found for the MMIm salt, [MMIm](3) [tcmel_3B]·2.66 CH(2)Cl(2), in which weak hydrogen bonds with the acidic proton of the MMIm ion are observed. On the basis of computations the energetics, structural trends, and charge transfer of adduct anion formation were studied., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The impact of microhydration on the electronic structure and reactivity of the H(3)O moiety is investigated by ab initio calculations. In the gas phase, H(3)O is a radical with spin density localized on its hydrogen end, which is only kinetically stable and readily decomposes into a water molecule and a hydrogen atom. When solvated by a single water molecule, H(3)O preserves to a large extent its radical character, however, two water molecules are already capable to shift most of the spin density to the solvent. With three solvating water molecules this shift is practically completed and the system is best described as a solvent-separated pair of a hydronium cation and a hydrated electron. The electronic structure of this system and its proton transfer reactivity leading to formation of a hydrogen atom already resemble those of a proton-electron pair in bulk water.

The process of electron localization on a cluster of 32 water molecules at 20, 50, and 300 K is unraveled using ab initio molecular dynamics simulations. In warm, liquid clusters, the excess electron relaxes from an initial diffuse and weakly bound structure to an equilibrated, strongly bound species within 1.5 ps. In contrast, in cold, glassy clusters the relaxation processes is not completed and the electron becomes trapped in a metastable surface state with an intermediate binding energy. These results question the validity of extrapolations of the properties of solvated electrons from cold clusters of increasing size to the liquid bulk.

The coordination chemistry of the bis(diphenylmethylsilyl)amine ligand, HN(SiMePh(2))(2), with the heavy alkali metals potassium and rubidium has been investigated to study its effect on the structure of the resulting compounds. The compounds exhibit extensive intra- and intermolecular M-pi interactions, creating 1-D coordination polymers, [K{N(SiMePh(2))(2)}](infinity) (1) and [Rb{N(SiMePh(2))(2)}](infinity) (3). This motif is maintained in the presence of tetrahydrofuran (THF), as seen in [K{N(SiMePh(2))(2)}thf](infinity) (2). In contrast, use of the tridentate PMDTA allows isolation of a monomeric species, K(pmdta)N(SiMePh(2))(2) (4), which exhibits both agostic and M-pi interactions. The incorporation of macrocyclic 18-crown-6, results in the formation of a rare non-metal bound amido species, {[K(18-crown-6)N(SiMePh(2))(2)]}(infinity) (5), stabilized by M-pi interactions from adjacent [N(SiMePh(2))(2)](-) ligands propagating 1-D coordination polymers.

Differential production cross sections of K+/- mesons have been measured in p + C and p + Au collisions at 1.6, 2.5, and 3.5 GeV proton beam energy. At beam energies close to the production threshold, the K- multiplicity is strongly enhanced with respect to proton-proton collisions. According to microscopic transport calculations, this enhancement is caused by two effects: the strangeness exchange reaction NY --> K- NN and an attractive in-medium K- N potential at saturation density.

Azimuthal distributions of pi+, K+, and K- mesons have been measured in Au+Au reactions at 1.5A GeV and Ni+Ni reactions at 1.93 A GeV. In semicentral collisions at midrapidity, pi+ and K+ mesons are emitted preferentially perpendicular to the reaction plane in both collision systems. In contrast for K- mesons in Ni+Ni reactions, an in-plane elliptic flow was observed for the first time at these incident energies.

Differential production cross sections of K- and K+ mesons have been measured in Ni+Ni and Au+Au collisions at a beam energy of 1.5 A GeV. The K(-)/K(+) ratio is found to be nearly constant as a function of the collision centrality and system size. The spectral slopes and the polar emission pattern differ for K- and K+ mesons. These observations indicate that K+ mesons decouple earlier from the fireball than K- mesons.

An exclusive measurement of the Coulomb breakup of 8B into 7Be+p at 254A MeV allowed the study of the angular correlations of the breakup particles. These correlations demonstrate clearly that E1 multipolarity dominates and that E2 multipolarity can be neglected. By using a simple single-particle model for 8B and treating the breakup in first-order perturbation theory, we extract a zero-energy S factor of S17(0)=18.6+/-1.2+/-1.0 eV b, where the first error is experimental and the second one reflects the theoretical uncertainty in the extrapolation.

The production of pions and kaons has been measured in 197Au+197Au collisions at beam energies from 0.6 to 1.5A GeV with the kaon spectrometer at SIS/GSI. The K+ meson multiplicity per nucleon is enhanced in Au+Au collisions by factors up to 6 relative to C+C reactions, whereas the corresponding pion ratio is reduced. The ratio of the K+ meson excitation functions for Au+Au and C+C collisions increases with decreasing beam energy. This behavior is expected for a soft nuclear equation-of-state.

A series of highly reactive heavy alkali metal phosphides was prepared by treating trimethylsilyl-substituted phosphines with alkali metal tert-butyl alcoholates. The compounds are formed in excellent yield and purity, and the side product can be easily removed in a vacuum. The high synthetic potential of this reaction route was further shown by utilizing excess alkali metal tert-butyl alcoholates in reaction with silyl substituted phosphines. In all cases, only monometalated products were isolated. In the course of this work the crystal structures of the bis(trimethylsilyl)phosphides [K(thf)P(SiMe(3))(2)](infinity), 1a, [Rb(thf)P(SiMe(3))(2)](infinity), 1b, and [Cs(thf)P(SiMe(3))(2)](infinity), 1c, were obtained. The compounds display polymeric ladder-type structures. Compounds 1a,b are isomorphous, while compound 1c displays a slightly altered local geometry. Despite small differences in local geometry, the coordination spheres for the phosphorus atoms and the alkali metal are fairly similar. The five coordinate phosphorus atoms are connected to three alkali metal centers in addition to two trimethylsilyl groups. The alkali metals are four coordinate with ligations to three phosphorus centers in addition to one thf oxygen donor. Compounds 1a-c were characterized using elemental analysis, NMR spectroscopy, and X-ray crystallography. Crystal data with Mo Kalpha (lambda = 0.710 73 Å) at 150 K are as follows: 1a, a = 6.4261(2) Å, b = 12.4119(2) Å, c = 21.5447(4) Å, V = 1718.41(7) Å(3), Z = 4, orthorhombic, space group P2(1)2(1)2(1), 3427 independent reflections, R1 (all data) = 0.0351; 1b, a = 6.5338(2) Å, b = 12.5664(3) Å, c = 21.5537(5) Å, V = 1769.70(8) Å(3), Z = 4, orthorhombic, space group P2(1)2(1)2(1), 4195 independent reflections, R1 (all data) = 0.0776; 1c, a = 11.3515(1) Å, b = 22.3445(3) Å, c = 7.2501(1) Å, beta = 96.017(1) degrees, V = 1828.81(4) Å(3), Z = 4, monoclinic, space group P2(1)/c, 4343 independent reflections, R1 (all data) = 0.0811.

In the last three years, of a total of 617 patients undergoing surgery for ischemic heart disease, 53 were women (8.6%). With one exception, all were in or shortly before the menopause. As compared with men, the women were found to have a preponderance of risk factors. The most unfavorable combination, that of hypertension and hypercholesterolemia, was present in one-third of the patients. Hospital mortality for isolated revascularization was higher in women at 4.9% than in men at 1.5%. The one-year survival rates, however, of 94.4% and 95%, respectively, did not differ between the two sexes. In women, the number of grafts per patient was 2.1 as compared with 2.9 in men. Complete revascularization was achieved less frequently in women than in men; similarly graft patency rate at one year of 66% in women was less than the 84% observed in men. The more marked coronary sclerosis as well as morphologic characteristics of coronary arteries in women construe a special challenge to the surgeon and prerequisite a high degree of technical skill.

At present international the regional cytostatic chemotherapy for hepatic metastases is used by the intraarterial way. Newest methods are the technically very pretentious intraarterial perfusion with venous hemofiltration and the chemo-embolization of the hepatic artery requiring meanwhile an adjuvant systemic chemotherapy because the chemo-embolization influences only the arterially supplied part of the metastases. By the combination of the transumbilical intraportal chemotherapy formerly developed in the Central Institute for Cancer Research Berlin-Buch with the intraarterial chemo-embolization it is possible to reduce considerably the technical expenditure and to increase the regional concentration of cytostatics simultaneous avoiding the load of the whole organism. The bases of this new method and the technical procedure are discussed.