Can graphynes turn into graphene at room temperature?

The thermal stability of α-, β-, 6,6,12-graphyne and graphdiyne was studied by a statistic model, which was seriously tested by classical molecular dynamics (MD) simulations. By first-principle calculations of related potential energy curves (PEC), the model predicts that all the lifetime of free-standing single layer graphynes is more than 10⁴⁴ years at room temperature. The sheets are predicted to be very stable even if the temperature gets up to 1000 K, but they quickly turn into graphene if the temperature is above 2000 K.     

Sphingolipids in the gut? Which are the important issues?

Glycosphingolipids and sphingomyelin (SM) are important components of the apical brush border and the Golgi and endocytic vesicles of the gut epithelium. In particular, glucosylceramide is abundant in the microvilli. Synthesis and degradation of mucosal sphingolipids and targeting of sphingolipids to distinct cell compartments during cell differentiation are thus important features of intestinal lipid metabolism. Sphingolipids are also present in the ordinary Western diet, and sphingolipid‐rich formulations of dairy, plant or yeast origin are now available for studies of their biological effects in animals and humans. Since sphingolipids account for a large part of the polar lipids in milk, their digestion and effects in the suckling infant is of particular interest. Dietary sphingolipids are slowly digested and the exposure of the whole gut to sphingolipids and their metabolites can be increased by dietary supply. Metabolites from dietary sphingolipids may have anti‐inflammatory and anticarcinogenic effects and undigested sphingolipids may be protective. Dietary sphingolipids inhibit cholesterol absorption and may have beneficial metabolic effects. Some mucosal sphingolipids have blood group A, B and H reactivity and some act as receptors for bacterial toxins and virus. Sphingolipid signaling triggered by mucosal‐bacterial interaction may be important in both the gut and the bronchi.     

How good are the Electrodes we use in PEFC?

Basically, companies and laboratories implement production methods for their electrodes on the basis of experience, technical capabilities and commercial preferences. But how does one know whether they have ended up with the best possible electrode for the components used? What should be the (i) optimal thickness of the catalyst layer? (ii) relative amounts of electronically conducting component (catalyst, with support – if used), electrolyte and pores? (iii) “particle size distributions” in these mesophases? We may be pleased with our MEAs, but could we make them better? The details of excellently working MEA structures are typically not a subject of open discussion, also hardly anyone in the fuel cell business would like to admit that their electrodes could have been made much better. Therefore, we only rarely find (far from systematic) experimental reports on this most important issue. The message of this paper is to illustrate how strongly the MEA morphology could affect the performance and to pave the way for the development of the theory. Full analysis should address the performance at different current densities, which is possible and is partially shown in this paper, but vital trends can be demonstrated on the linear polarization resistance, the signature of electrode performance. The latter is expressed through the minimum number of key parameters characterizing the processes taking place in the MEA. Model expressions of the percolation theory can then be used to approximate the dependence on these parameters. The effects revealed are dramatic. Of course, the corresponding curves will not be reproduced literally in experiments, since these illustrations use crude expressions inspired by the theory of percolation on a regular lattice, whereas the actual mesoscopic architecture of MEA is much more complicated. However, they give us a flavour of reserves that might be released by smart MEA design.     

Stability of rare earth oxides in a moist environment at high temperatures—Experimental and thermodynamic studies. Part I: The way to assess thermodynamic parameters from volatilisation rates

A methodology based on a weight loss measurement was used to quantify the volatility of yttria in high temperature water vapor. This method was first assessed on silica. Sintered materials with a shape of pellets were exposed at temperatures between 1000 and 1400 °C in air with 50 kPa of water at atmospheric pressure, under a flowing gas velocity of 5 cm s^?1. Besides the volatilisation rate, the nature of the volatile gaseous species was determined using a kinetic study. Knowing the nature of flows in the furnace, partial pressures of yttrium (oxy-)hydroxide in equilibrium over Y₂O₃ were calculated, and used to assess the enthalpies of formation of YO(OH) and Y(OH)₃.     

Can We Treat Neuroinflammation in Alzheimer’s Disease?

Alzheimer’s disease (AD), considered the most common type of dementia, is characterized by a progressive loss of memory, visuospatial, language and complex cognitive abilities. In addition, patients often show comorbid depression and aggressiveness. Aging is the major factor contributing to AD; however, the initial cause that triggers the disease is yet unknown. Scientific evidence demonstrates that AD, especially the late onset of AD, is not the result of a single event, but rather it appears because of a combination of risk elements with the lack of protective ones. A major risk factor underlying the disease is neuroinflammation, which can be activated by different situations, including chronic pathogenic infections, prolonged stress and metabolic syndrome. Consequently, many therapeutic strategies against AD have been designed to reduce neuro-inflammation, with very promising results improving cognitive function in preclinical models of the disease. The literature is massive; thus, in this review we will revise the translational evidence of these early strategies focusing in anti-diabetic and anti-inflammatory molecules and discuss their therapeutic application in humans. Furthermore, we review the preclinical and clinical data of nutraceutical application against AD symptoms. Finally, we introduce new players underlying neuroinflammation in AD: the activity of the endocannabinoid system and the intestinal microbiota as neuroprotectors. This review highlights the importance of a broad multimodal approach to treat successfully the neuroinflammation underlying AD.     

What are the Mechanisms Behind a Parasite-Induced Decline in Nestmate Recognition in Ants?

Social insects have developed sophisticated recognition skills to defend their nests against intruders. They do this by aggressively discriminating against non-nestmates with deviant cuticular hydrocarbon (CHC) signatures. Studying nestmate recognition can be challenging as individual insects do not only vary in their discriminatory abilities, but also in their motivation to behave aggressively. To disentangle the influence of signaling and behavioral motivation on nestmate recognition, we investigated the ant Temnothorax nylanderi, where the presence of tapeworm-infected nestmates leads to reduced nestmate recognition among uninfected workers. The parasite-induced decline in nestmate recognition could be caused by higher intra-colonial cue diversity as tapeworm-infected workers are known to exhibit a modified hydrocarbon signature. This in turn may broaden the neuronal template of their nestmates, leading to a higher tolerance towards alien conspecifics. To test this hypothesis, we exchanged infected ants between colonies and analyzed their impact on CHC profiles of uninfected workers. We demonstrate that despite frequent grooming, which should promote the transfer of recognition cues, CHC profiles of uninfected workers neither changed in the presence of tapeworm-infected ants, nor did it increase cue diversity among uninfected nestmates within or between colonies. However, CHC profiles were systematically affected by the removal of nestmates and addition of non-nestmates, independently from the ants’ infection status. For example, when non-nestmates were present workers expressed more dimethyl alkanes and higher overall CHC quantities, possibly to achieve a better distinction from non-nestmates. Workers showed clear task-specific profiles with tapeworm-infected workers resembling more closely young nurses than older foragers. Our results show that the parasite-induced decline in nestmate recognition is not due to increased recognition cue diversity or altered CHC profiles of uninfected workers, but behavioral changes might explain tolerance towards intruders.     

Biometrical modelling in genetics: are complex traits too complex?

The field of traditional biometrical genetics uses mixed-effects models to quantify the influence of genetic and environmental factors on a biological trait, based essentially on estimating within-family trait correlations. Such analyses provide a useful preview of what may be discovered with the emerging full-scale genotyping strategies. However, biometrical analyses require unrealistically large sample sizes to obtain a reasonable precision, particularly for dichotomous traits. In addition, it may be very difficult to separate genetic and environmental effects because environmental correlations are poorly understood. We illustrate these and other difficulties using population-based cousins and nuclear family data for birth weight, collected from the Medical Birth Registry of Norway.     

Can Developments in Tissue Optical Clearing Aid Super-Resolution Microscopy Imaging?

The rapid development of super-resolution microscopy (SRM) techniques opens new avenues to examine cell and tissue details at a nanometer scale. Due to compatibility with specific labelling approaches, in vivo imaging and the relative ease of sample preparation, SRM appears to be a valuable alternative to laborious electron microscopy techniques. SRM, however, is not free from drawbacks, with the rapid quenching of the fluorescence signal, sensitivity to spherical aberrations and light scattering that typically limits imaging depth up to few micrometers being the most pronounced ones. Recently presented and robustly optimized sets of tissue optical clearing (TOC) techniques turn biological specimens transparent, which greatly increases the tissue thickness that is available for imaging without loss of resolution. Hence, SRM and TOC are naturally synergistic techniques, and a proper combination of these might promptly reveal the three-dimensional structure of entire organs with nanometer resolution. As such, an effort to introduce large-scale volumetric SRM has already started; in this review, we discuss TOC approaches that might be favorable during the preparation of SRM samples. Thus, special emphasis is put on TOC methods that enhance the preservation of fluorescence intensity, offer the homogenous distribution of molecular probes, and vastly decrease spherical aberrations. Finally, we review examples of studies in which both SRM and TOC were successfully applied to study biological systems.     

Phase relation studies in the CeO2-Eu2O3 system at 1500 to 600 °C in air

Materials based on CeO₂-Eu₂O₃ system are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. To address this challenge, the subsection of the phase diagram for 600, 1100 and 1500 °C has been elucidated. Samples of different compositions have been prepared from nitrate acid solutions using conventional ceramic techniques; evaporation, drying, and calcinations. The phase relations in the binary CeO₂-Eu₂O₃ system at 600–1500 °C in air were studied from the heat treated samples using X-ray diffraction analysis, polarized light microscopy investigation and scanning electron microscopy in the overall concentration range. It was established that in the binary CeO₂-Eu₂O₃ system there exist fields of solid solutions based on monoclinic (B) modification of Eu₂O₃, cubic (C) modification of Eu₂O₃ and cubic modification of CeO₂ with fluorite-type structure (F). The systematic study that covered whole composition range excluded formation of new phases. The refined lattice parameters of the unit cells and the boundaries of the homogeneity fields for solid solutions were determined.     

Carbon nanotubes: are they dispersed or dissolved in liquids?

Carbon nanotubes (CNTs) constitute a novel class of nanomaterials with remarkable applications in diverse domains. However, the main intrincsic problem of CNTs is their insolubility or very poor solubility in most of the common solvents. The basic key question here is: are carbon nanotubes dissolved or dispersed in liquids, specifically in water? When analyzing the scientific research articles published in various leading journals, we found that many researchers confused between "dispersion" and "solubilization" and use the terms interchangeably, particularly when stating the interaction of CNTs with liquids. In this article, we address this fundamental issue to give basic insight specifically to the researchers who are working with CNTs as well asgenerally to scientists who deal with nano-related research domains.Among the various nanomaterials, CNTs gained widespread attention owing to their exceptional properties, good chemical stability, and large surface area [1,2]. CNTs are extremely thin tubes and feature an extremely enviable combination of mechanical, thermal, electrical, and optical properties. Their size, shape, and properties construct them as prime contenders for exploiting the growth of a potentially revolutionary material for diverse applications.Nevertheless, the main intrinsic drawback of CNTs is their insolubility or extremely poor solubility in most of the common solvents due to their hydrophobicity, thus creating it tricky to explore and understand the chemistry of such material at the molecular level and device applications. Though diverse approaches [3] have been introduced to improve the dispersion of CNTs in different solvents including water, challenges still remain in developing simple, green, facile, and effective strategies for a large-scale production of CNT dispersions. To this end, in many studies a wide range of agents have been used. To give a few examples: solvents [4], biopolymers [5], and surfactants [6]. Meanwhile, when analyzing the scientific research articles published in various leading journals, regarding the dispersion of CNTs, it is really puzzling owing to the usage of different terminologies with respect to the dispersion of CNTs. Most of the studies indicated "dispersion"; however, considerable quantities of articles were published with the term "solubilization", which can be evidently seen from the literature analysis [7]. Hence, many researchers confound "dispersion" and "solubilization" and use the terms interchangeably, especially when describing the interaction of CNTs with solvents. Many scientists have mentioned that CNTs can be "solubilized in water or organic solvents" by means of polymers and/or surfactants, which is ambiguous. It is evident that there is, as a result of that, a lot of confusion regarding this fundamental matter. The basic and fundamental key question here is: are CNTs dissolved or dispersed in a liquid?Basically, "dispersion" and "solubilization" are different phenomena. Dispersion and solubilization can be defined as "a system, in which particles of any nature (e.g., solid, liquid, or gas) are dispersed in a continuous phase of a different composition (or state)" [8] and a "process, by which an agent increases the solubility or the rate of dissolution of a solid or liquid solute" [9], respectively. Hence, in general, the dispersion of solute particles in solvents leads to the formation of colloids or suspensions, and solutions may be obtained as a result of solubilization of solute molecules or ions in the specified solvent. Furthermore, dispersion is mostly related to solute particles, whereas solubility or solubilization is generally connected with solute molecules or ions.The main differences between a colloid and a solution are: A solution is homogenous and remains stable and does not separate after standing for any period of time. Further it cannot be separated by standard separation techniques such as filtration or centrifugation. A solution looks transparent and it can transmit the light. Also, solutions contain the solute in a size at the molecular or ionic level, typically less than 1 nm or maximum a few nm in all dimensions. A colloid is a mixture with particles sizes between 1 and 1000 nm in at least one dimension. It is opaque, non-transparent, and the particles are large enough to scatter light. Colloids are not as stable as solutions and the dispersed particles (comparatively larger-sized particles) may be conveniently separated by standard separation techniques such as (ultra)centrifugation or filtration. Frequently, dispersed particles in colloidal systems may slowly agglomerate owing to inter-particle attractions over prolonged periods of time and, as a result, colloidal dispersions may form flocs or flakes.As far as CNTs are concerned, even though the diameter of the tubes is in the nanometer range (approximately between 0.4 and 3 nm for single-walled carbon nanotubes, and 1.4 and 100 nm for multi-walled carbon nanotubes) [10], their length can be up to several micrometers to millimeters. Further, it is a well-known fact that CNTs are not equal in size with respect to both diameter and length. Hence, the result of dispersion techniques mostly used and adopted to produce well-dispersed CNTs in either aqueous and/or organic media are typically dispersions of differently sized tubes. Consequently, based on the definition [6,7] and the abovementioned points, the mixture of CNTs and water or organic solvents, whether in the presence or non-presence of dispersing agents such as surfactants or polymers, is just a colloidal dispersion and not a solution. Figure ​Figure11 shows the schematic illustration for the formation of dispersed CNTs in a liquid with the aid of a dispersing agent. Simultaneously, the dispersion can result in a debundling or individualization of the bundled CNTs.Open in a separate windowFigure 1Schematic showing the transition of the bundled to the individualized, dispersed state of carbon nanotubes in a liquid with the aid of a dispersing agent.Therefore, "solubilization" is a process to achieve a stable solution, whereas "dispersion" is a form of colloidal system. Here we conclude that the mixture obtained by using CNTs and a liquid medium (water or organic solvents) with or without surfactants or polymers is a dispersion of CNTs in the medium, but not a solution. Further, in our opinion, one cannot solubilize CNTs in water or organic solvents. Hence, we recommend to restrict the use of the term "solubilization" or "solution," instead we should use the term "dispersion" or "colloid," when dealing with CNTs. Further, we think that this should be also applicable for nanoparticles of comparable dimensions such as metal and metal oxide nanoparticles, polymer nanoparticles, etc., if the criteria of the definitions given above are fulfilled.In short, the term "dispersion" should exclusively be used as far as CNTs are concerned, and the use of the term "solution" should be avoided or restricted.     

Can the maximum volume fraction ensure optimum reinforcement in short-fiber composites?

Short sisal fiber composites (SSFCs) based on a pectin matrix were prepared and characterized mechanical and optically. Different concentrations (1–30 wt %) of fibers were used to evaluate the packing effect on the reinforcement of a polymer matrix. Theoretical models were used to obtain the maximum packing or volume fraction (ϕ_max) of randomly oriented short fibers and its relationship with the mechanical parameters. A higher elastic modulus and tensile strength were observed when the fiber content was increased in the composite at a fixed aspect ratio (length/diameter = 2.8). Material selection charts showed that SSFCs with a fiber concentration of 20 wt % had a higher reinforcement effect at ϕ_max, as was predicted through theoretical models. Nevertheless, SSFCs with a fiber concentration of 7 wt % presented optimum reinforcement because it resulted in the strongest and lightest composite material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47821.     

Can Clethra barbinervis Distinguish Nickel and Cobalt in Uptake and Translocation?

Clethra barbinervis Sieb. et Zucc. accumulates Nickel (Ni) and Cobalt (Co) at high concentrations., We hypothesized that C. barbinervis cannot distinguish between Ni and Co because of the similar chemical properties of these two elements. To confirm this hypothesis and understand the role of these elements in C. barbinervis, we conducted a hydroponic split-root experiment using Ni and Co solutions. We found that the bioconcentration factor (BCF; metal concentration of each tissue/metal concentrations of each treatment solution) of Ni and Co did not significantly differ in the roots, but the BCF for Co was higher than that for Ni in the leaves. The leaves of C. barbinervis accumulated Ni or Co at high concentrations. We also found the simultaneous accumulation of Ni and Co by the multiple heavy metal treatments (Ni and Co) at high concentrations similar to those for the single treatments (Ni or Co). Elevated sulfur concentrations occurred in the roots and leaves of Co-treated seedlings but not in Ni. This result indicates that S was related to Co accumulation in the leaves. These results suggest that C. barbinervis distinguishes between Ni and Co during transport and accumulation in the leaves but not during root uptake.     

Can solute segregation in ceramic materials be reduced by lattice strain?

Lattice strain is a relatively unexplored route to modify the degradation effects in functional oxides for high‐temperature electrochemical devices. In this paper, we present results on the segregation of Gd to the surface of strained Gd_0.1Ce_0.9O_2‐δ films using low‐energy ion scattering to assess the surface composition. The potential for strain‐modified segregation is discussed as well as the challenges in studying and implementing it.     

Which Chemical Constituents from Dog Feces are Involved in its Food Repellent Effect in Sheep?

This study is an attempt to identity the active chemicals (signal) of the odor of dog feces that suppress feeding in domestic sheep. The repellent effects of the odors of dog, wolf, pig, and sheep feces (potential predator and nonpredator species) were assessed on sheep, using a food-choice situation. The odors of wolf and dog feces had the highest repellent effect. A total pentane extract of dog feces was split by micropreparative gas chromatography and the fractions obtained were analyzed and presented to sheep in a food-choice situation. The quantitatively major constituents of the pentane extract, identified by gas chromatography–mass spectrometry, are indole and fatty acids. In food repellency tests, indole had no repellent effect. The active odorous signal contained in dog feces appears to consist of fatty acids mixed with neutral compounds acting synergically. These experiments underline the complexity of this biological signal and constitute a first step in the development of a practical repellent for ungulates.     

Can Drying Be an Alternative Tissue Preservation Method in Cancer Research Biobanking?

The currently available methods for conservation of biobank material are mainly based on formalin fixation or the use of different freezing techniques. For molecular biological analysis, it is common to use quick freezing and low-temperature storage of the tissue materiel. This is a very energy-intensive and expensive method that requires advanced infrastructure, including monitoring and control procedures. The purpose of this work has been to study drying as an alternative process to cryogenic storage of undried biobank material, especially for use in cancer research groups.

Fast freezing has been shown to be suitable to preserve the integrity of RNAs, while traditional formalin fixation preserves proteins and thus morphology in a good way. Various fresh-harvested murine tissues, such as lung, heart, skeletal muscle, liver, and kidney, were quickly frozen in liquid nitrogen and then subsequently dried at +5°C and ?10°C, respectively, in a heat pump dryer. After drying, the RNA integrity was measured. The dried material was then stored for five months at +4°C and ?20°C in commercial refrigerators, with subsequent measurement of RNA integrity. Dried materials were also evaluated with light microscopy and by electron microscopy with respect to tissue and cell structure. The same pattern was found for all five murine tissues. We conclude that drying at temperatures below 0°C is most careful to preserve the RNA integrity, with approximately the same RIN score of dried and non-dried samples for all five tissues. What characterized the general pattern of stored samples is that drying leads to a preservation of RNA integrity. Moreover, architecture in tissue resembled normal sections prepared from fresh tissue. In some places in the rim of the tissue sample, the lung tissue revealed alveolar-like morphology. In the electron microscope, few organelles other than the nuclei could be identified. Drying of biological material is a promising and cost-effective method for biobanks that store tissue, compared to cryogenic storage of undried material. Degradation of RNA, measured by the RIN number, is a critical factor in storing biobank tissue. In low-temperature dried material, the RIN factor is at the same level as storage of undried material at cryogenic temperatures, which is the common way of storing biobank material today. In this study, a heat pump dryer was used successfully to establish drying temperatures below and above the freezing point of the material. Further work has to be done in order to study different drying methods, drying conditions, and drying costs.     

Can steady-state momentum equations be used in modelling pressurization of adsorption beds?

Modelling of pressurization and blowdown steps of a pressure swing adsorption (PSA) cycle has been carried out using a steady-state momentum equation (Darcy or Ergun) locally in the bed. There has been some controversy about the validity of such an approach since Darcy's or Ergun's equations are strictly valid only for quasi-stable flow, and during pressurization at short times, the flow is unstable. In order to check the assumptions usually made in modelling isothermal pressurization, three models are developed. Model I includes mass balance and unsteady-state mechanical energy balance for a packed bed with non-porous, inert particles; Model II neglects the kinetic energy change in the mechanical energy balance and Model III considers a steady-state mechanical energy balance. The latter model is the one used in previous work. The numerical tool used to solve all the model equations is the moving finite element method (MFEM) with polynomial approximation of any degree in each element developed by C. Sereno¹. Comparison of simulation results for the various models showed that steady-state momentum equations can be safely used in modelling pressurization of adsorbers.     

How Can Malnutrition Affect Autophagy in Chronic Heart Failure? Focus and Perspectives

Chronic heart failure (CHF) is a disease with important clinical and socio-economic ramifications. Malnutrition and severe alteration of the protein components of the body (protein disarrangements), common conditions in CHF patients, are independent correlates of heart dysfunction, disease progression, and mortality. Autophagy, a prominent occurrence in the heart of patients with advanced CHF, is a self-digestive process that prolongs myocardial cell lifespan by the removal of cytosolic components, such as aging organelles and proteins, and recycles the constituent elements for new protein synthesis. However, in specific conditions, excessive activation of autophagy can lead to the destruction of molecules and organelles essential to cell survival, ultimately leading to organ failure and patient death. In this review, we aim to describe the experimental and clinical evidence supporting a pathophysiological role of nutrition and autophagy in the progression of CHF. The understanding of the mechanisms underlying the interplay between nutrition and autophagy may have important clinical implications by providing molecular targets for innovative therapeutic strategies in CHF patients.     

Biocatalyst replacement by mimetics in bioconversions: Can the time-scale be predicted?

Enzyme mimics (mimetics) include abzymes (catalytic antibodies), RNA molecules (ribozymes), and enzyme analogues synthesized upon a polypeptide backbone structure (synzymes). Also, there is a variety of model systems such as the zeolite-membrane systems containing metal complexes, which mimic cytochrome P-450. Enzymes are being subjected to redesign procedures to introduce desired features such as thermostability that could improve their industrial usefulness: but even such novel enzymes may not be able in the near future to out-perform the enzyme mimics in all circumstances, such as at temperatures above about 120°C or under completely non-aqueous conditions.