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Hypothesis: Saponins are a class of plant derived surfactants which are widely used in food related foams and emulsions, aerated drinks, and in pharmaceuticals and cosmetics. As a ...potential biosourced and renewable ingredient in a wider range of surfactant based formulations their potential is intimately associated with their mixing with synthetic surfactants. As such the nature of the mixed saponin-surfactant self-assembly is an important characteristic to investigate and understand. The unconventional structure of the saponins compared to the conventional synthetic surfactants poses some interesting constraints on the structures of the mixed aggregates.
Experiments: Small angle neutron scattering, SANS, is used to investigate the structure of the saponin, escin, mixed with a range of nonionic surfactants with different ethylene oxide groups, from triethylene glycol monododecyl ether, C12E3, to dodecaethylene glycol monododecyl ether, C12E12.
Findings: The scattering data reveal a complex evolution in the solution self-assembled structure with varying escin / nonionic composition and ethylene oxide chain length. The rich structural development comprises of the evolution from the elongated micelle structure of escin to the micelle structure of the nonionic surfactant. At the intermediate solution compositions the structure is predominantly planar, comprising mostly of planar / micellar mixed phases. The nature of the planar structures depend upon the ethylene oxide chain length and the solution composition, and include lamellar, bilamellar vesicle, multilamellar vesicle, and nanovesicle structures, in common with what is observed in other surfactant mixtures.
A new birefringent Ba sub(2)Mg(B sub(3)O sub(6 )) sub(2) (BMBO) crystal with dimensions of 41 27 9 mm super(3) has been grown from a stoichiometric melt. The structure of BMBO, determined from ...single-crystal X-ray diffraction data, demonstrates that it belongs to the rhombohedral space group R3&cmb.macr; with unit cell parameters of a= 7.094(5) Aa, c= 16.721(15) Aa and Z= 3. BMBO melts congruently with a melting point of 1000 degree C and does not show any phase transitions from room temperature to the melting point. It is found that the BMBO crystal has a wide transmission range (178-3000 nm), large birefringence ( Delta n= n sub(o) - n sub(e) = 0.2045-0.0767 from 190 nm to 3 mu m) and high chemical stability. The BMBO crystal may serve as a unique birefringent crystal for polarizers, beam displacers and beam splitters in the ultraviolet, especially in the deep ultraviolet range.
Chemically modified mRNA is an efficient, biocompatible modality for therapeutic protein expression. We report a first-time-in-human study of this modality, aiming to evaluate safety and potential ...therapeutic effects. Men with type 2 diabetes mellitus (T2DM) received intradermal injections of modified mRNA encoding vascular endothelial growth factor A (VEGF-A) or buffered saline placebo (ethical obligations precluded use of a non-translatable mRNA control) at randomized sites on the forearm. The only causally treatment-related adverse events were mild injection-site reactions. Skin microdialysis revealed elevated VEGF-A protein levels at mRNA-treated sites versus placebo-treated sites from about 4-24 hours post-administration. Enhancements in basal skin blood flow at 4 hours and 7 days post-administration were detected using laser Doppler fluximetry and imaging. Intradermal VEGF-A mRNA was well tolerated and led to local functional VEGF-A protein expression and transient skin blood flow enhancement in men with T2DM. VEGF-A mRNA may have therapeutic potential for regenerative angiogenesis.
While the molecular mechanisms promoting activation of the Nod-like Receptor (NLR) family member NLRP3 inflammasome are beginning to be defined, little is known about the mechanisms that regulate the ...NLRP3 inflammasome. Acute (up to 4 hours) LPS stimulation, followed by ATP is frequently used to activate the NLRP3 inflammasome in macrophages. Interestingly, we observed that the ability of LPS to license NLRP3 is transient, as prolonged (12 to 24 hours) LPS exposure was a relatively ineffective priming stimulus. This suggests that relative to acute LPS, chronic LPS exposure triggers regulatory mechanisms to dampen NLRP3 activation. Transfer of culture supernatants from macrophages stimulated with LPS for 24 hours dramatically reduced ATP- and nigericin-induced NLRP3 inflammasome activation in naïve macrophages. We further identified IL-10 as the secreted inflammasome-tolerizing factor that acts in an autocrine manner to control activation of the NLRP3 inflammasome. Finally, we demonstrated that IL-10 dampens NLRP3 expression to control NLRP3 inflammasome activation and subsequent caspase-8 activation. In conclusion, we have uncovered a mechanism by which chronic, but not acute, LPS exposure induces IL-10 to dampen NLRP3 inflammasome activation to avoid overt inflammation.
Two new noncentrosymmtric fluoroborates, BaZnBO3F and BaMgBO3F, have been synthesized and characterized. It is found that BaZnBO3F possesses a P6̅ space group with cell parameters of a = 5.0657(1) Å, ...c = 4.2800(1) Å, and Z = 1. The structure is built up by five coordinated trigonal bipyramidal ZnO3F2 polyhedra and triangular BO3 groups. The ZnO3F2 bipyramid shares its three equatorial oxygen atoms with three separate BO3 groups to form a ZnO3−BO3 layer, and the layers are linked by the apical fluorine atoms in the third dimension. Owing to its special coordination, ZnO3F2 forces its three neighboring BO3 groups to arrange into a perfect parallel alignment in the plane to give maximum contribution to the nonlinear optical (NLO) effect. Both calculation and powder second harmonic generation tests show that its effective NLO coefficient is on about the same order as that of LiB3O5. In contrast, in BaMgBO3F, which crystallizes in space group Cc with a = 17.614(3) Å, b = 30.546(6) Å, c = 8.060(2) Å, and β = 90.008(2)°, Mg coordinates to four oxygen and two fluorine atoms to form a severely distorted MgO4F2 octahedron. It also uses four equatorial oxygen atoms, sharing with three BO3 groups to form a MgO4−BO3 layer, and again the layers are linked by the apical F atoms. Every Mg atom links with one edge-sharing and two corner-sharing BO3 groups, leaving the BO3 group misaligned and resulting in most of their contributions to NLO effects being canceled.
Collisionless shocks are ubiquitous in the Universe as a consequence of supersonic plasma flows sweeping through interstellar and intergalactic media. These shocks are the cause of many observed ...astrophysical phenomena, but details of shock structure and behavior remain controversial because of the lack of ways to study them experimentally. Laboratory experiments reported here, with astrophysically relevant plasma parameters, demonstrate for the first time the formation of a quasiperpendicular magnetized collisionless shock. In the upstream it is fringed by a filamented turbulent region, a rudiment for a secondary Weibel-driven shock. This turbulent structure is found responsible for electron acceleration to energies exceeding the average energy by two orders of magnitude.
A central characteristic of living beings is the ability to learn from and respond to their environment leading to habit formation and decision making. This behavior, known as habituation, is ...universal among all forms of life with a central nervous system, and is also observed in single-cell organisms that do not possess a brain. Here, we report the discovery of habituation-based plasticity utilizing a perovskite quantum system by dynamical modulation of electron localization. Microscopic mechanisms and pathways that enable this organismic collective charge-lattice interaction are elucidated by first-principles theory, synchrotron investigations, ab initio molecular dynamics simulations, and in situ environmental breathing studies. We implement a learning algorithm inspired by the conductance relaxation behavior of perovskites that naturally incorporates habituation, and demonstrate learning to forget: a key feature of animal and human brains. Incorporating this elementary skill in learning boosts the capability of neural computing in a sequential, dynamic environment.Habituation is a learning mechanism that enables control over forgetting and learning. Zuo, Panda et al., demonstrate adaptive synaptic plasticity in SmNiO
perovskites to address catastrophic forgetting in a dynamic learning environment via hydrogen-induced electron localization.
Two types of fluorene-based organic dyes featuring T-shape/rod-shape molecular configuration with phenothiazine donor and cyanoacrylic acid acceptor have been synthesized and characterized as ...sensitizers for dye-sensitized solar cells. Phenothiazine is functionalized at either nitrogen (N10) or carbon (C3) to obtain T-shape and rod-like organic dyes, respectively. The effect of structural alternation on the optical, electrochemical, and the photovoltaic properties is investigated. The crystal structure determination of the dye containing phenyl linker revealed cofacial slip-stack columnar packing of the molecules. The trends in the optical properties of the dyes are interpreted using time-dependent density functional theory (TDDFT) computations. The rod-shaped dyes exhibited longer wavelength absorption and low oxidation potentials when compared to the corresponding T-shaped dyes attributable to the favorable electronic overlap between the phenothiazine unit and the rest of the molecule in the former dyes. However, the T-shaped dyes showed better photovoltaic properties due to the lowest unoccupied molecular orbital (LUMO) energy level favorable for electron injection into the conduction band of TiO2 and appropriate orientation of the phenothiazine unit rendering effective surface blocking to suppress the recombination of electrons between the electrolyte I3 – and TiO2. The electrochemical impedance spectroscopy investigations provide further support for the variations in the electron injection and transfer kinetics due to the structural modifications.
Recently, support vector machine (SVM) has excellent performance on classification and prediction and is widely used on disease diagnosis or medical assistance. However, SVM only functions well on ...two-group classification problems. This study combines feature selection and SVM recursive feature elimination (SVM-RFE) to investigate the classification accuracy of multiclass problems for Dermatology and Zoo databases. Dermatology dataset contains 33 feature variables, 1 class variable, and 366 testing instances; and the Zoo dataset contains 16 feature variables, 1 class variable, and 101 testing instances. The feature variables in the two datasets were sorted in descending order by explanatory power, and different feature sets were selected by SVM-RFE to explore classification accuracy. Meanwhile, Taguchi method was jointly combined with SVM classifier in order to optimize parameters C and γ to increase classification accuracy for multiclass classification. The experimental results show that the classification accuracy can be more than 95% after SVM-RFE feature selection and Taguchi parameter optimization for Dermatology and Zoo databases.
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Cationic surfactants have a wide range of applications, often associated with their affinity for a range of solid surfaces and their anti-microbial properties. Manipulating their ...adsorption and self-assembly properties is key to most applications, and this is commonly achieved through surfactant mixtures or manipulating their headgroup or alkyl chain structure. Achieving this through adjustments to their headgroup structure is less common in cationic surfactants than in anionic surfactants. Ethoxylation provides the ability to adjust the hydrophilic / hydrophobic balance, as extensively demonstrated in a range of anionic surfactants.
This same approach has been applied here to a range of ethoxylated cationic surfactants in the form of the quaternary ammonium salts, and their tertiary nonionic equivalents before quaternisation. Their adsorption and self-assembly properties are investigated using predominantly the neutron scattering techniques of neutron reflectivity, NR, and small angle neutron scattering, SANS.
The trends in the adsorption at the air–water interface and the self-assembly in aqueous solution demonstrate how the hydrophilic / hydrophobic balance can be adjusted by varying the degree of ethoxylation and the alkyl chain length, and illustrate the degree of interdependence of the different structural changes. The variation in the adsorption and the micelle structure shows how the surfactant conformation / packing changes as the degree of ethoxylation and alkyl chain length increases and how the introduction of charge induces further changes.
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