Stability of siloxane couplers on pure and fluorine doped SnO2 (110) surface: A first principles study

Siloxane is a favorable candidate as an anchor group that can be used to bind organic molecules to SnO₂ surfaces, with a wide range of practical applications. Therefore, adsorption geometries and energies of siloxane coupler on the SnO₂ (110) surface have been investigated in this study using quantum-chemical periodic density functional theory (DFT) calculations. We present a comparative study of different siloxane adsorption arrangements on pristine and fluorine doped SnO₂ surface. According to the calculations, the surface doping with fluorine leads to stabilization of the siloxane network at the stannic oxide surface. The trend is analyzed in terms of additional charge provided by F impurities to the chemisorbed oxygen atoms thus increasing the ionicity of their bonding. Implications of the current findings for the design of organic-metal oxide interface with better thermo-stability and improved electronic properties are discussed.     

Theoretical LSP detection rates for dark-matter detectors

Low-energy structure of the dark-matter detector nuclei ⁷¹Ga, ⁷³Ge and ¹²⁷I has been studied by using the nuclear shell model. The calculations have been done in realistic model spaces by using renormalized microscopic two-body interactions. The resulting ground states have been used to calculate theoretical predictions for detection rates of the lightest supersymmetric particle (LSP) in experiments studying elastic scattering of the LSP’s from atomic nuclei. Presented by T.S. Kosmas at the Workshop on calculation of double-beta-decay matrix elements (MEDEX’05), Corfu, Greece, September 26–29, 2005.     

Development of Counting Skills: Role of Spontaneous Focusing on Numerosity and Subitizing-Based Enumeration

Children differ in how much they spontaneously pay attention to quantitative aspects of their natural environment. We studied how this spontaneous tendency to focus on numerosity (SFON) is related to subitizing-based enumeration and verbal and object counting skills. In this exploratory study, children were tested individually at the age of 4-5 years on these skills. Results showed 2 primary relationships in children's number skills development. Performance in a number sequence production task, which is closely related to ordinal number sequence without reference to cardinality, is directly associated with SFON. Second, the association of SFON and object counting skills, which require relating cardinal and ordinal aspects of number, is mediated by subitizing-based enumeration. This suggests that there are multiple pathways to enumeration skills during development.     

Theoretical LSP detection rates for <Superscript>71</Superscript>Ga, <Superscript>73</Superscript>Ge,and <Superscript>127</Superscript>I dark-matter detectors

The low-energy structure of the dark-matter detector nuclei ⁷¹Ga, ⁷³Ge, and ¹²⁷I has been studied by using the microscopic quasiparticle-phonon model. The resulting ground states have been used to calculate theoretical predictions for detection rates of the lightest supersymmetric particle (LSP) in experiments studying elastic scattering of an LSP from an atomic nucleus. The highest rate, approximately 0.27 yr^?1kg^?1, among all the adopted SUSY parameters and renormalization schemes was provided by ¹²⁷I at the zero limit of the detector energy threshold.     

Practical Method for 2‐Hydroxyphenylketimine Synthesis

A series of hydroxyphenylketimines, of which 15 are new, was synthesized in methanol at high temperature (200°C) using a sealed steel reactor. This reaction setup especially enhances the synthesis of 2‐hydroxyphenylketimines, with yields up to six times higher than those obtained with the conventional acid‐catalyzed method under refluxing conditions. In fact, some imines were achievable only by the autoclave method.     

Properties and Polymerization of Biodegradable Thermoplastic Poly(Ester-urethane)

Abstract

Aliphatic polyesters, such as poly(lactic acids), need high molecular weight for acceptable mechanical properties. This can be achieved through ring-opening polymerization of lactides. The lactide route is, however, relatively complicated, and alternative polymerization routes are of interest. In this paper we report the properties of a polymer made by a two-step process: first a condensation polymerization of lactic acid and then an increase of the molecular weight with diisocyanate. The end product is then a thermoplastic poly(ester-urethane). The hydroxylterminated prepolymer was made with condensation polymerization of L–lactic acid and a small amount of 1,4-butanediol. The polymerization was performed in the melt under nitrogen and reduced pressure. The preparation of poly(ester-urethane) was done in the melt using aliphatic diisocyanates as the chain extenders reacting with the end groups of the prepolymer. The polymer samples were carefully characterized, including preliminary degradation studies. The results indicate that this route to convert lactic acid into thermoplastic biodegradable polymer has high potential. Lactic acid is converted into a mechanically attractive polymer with high yield, which could make the polymer suitable for high volume applications. The mechanical properties of the poly(ester-urethane) are comparable with those of poly(lactides). Capillary rheometer measurements indicate that the polymer is processible both by injection molding and extrusion.     

Crystalline Hybrid Solid Materials of Palladium and Decamethylcucurbit[5]uril as Recoverable Precatalysts for Heck Cross‐Coupling Reactions

A series of M? Pd? Me₁₀CB[5] (M=Li, Na, K, Rb, and Cs; Me₁₀CB[5]=decamethylcucurbit[5]uril) hybrid solid materials have been successfully synthesized for the first time through a simple diffusion method. These as‐prepared hybrid solids have been applied as phosphine‐free precatalysts for Heck cross‐coupling reactions with excellent catalytic performance and good recyclability. In the processes of the catalytic reactions, the activated Pd^II species were released from the crystalline hybrid precatalysts and transformed into catalytically active Pd nanoparticles, which have been demonstrated as key to carry on the catalytic reactions for the recoverable precatalysts M? Pd? Me₁₀CB[5] (M=K, Rb, and Cs). It has also been rationalized that the introduction of different alkali metals afforded crystalline hybrid precatalysts with different crystal structures, which are responsible for their diversified stability and reusability presented in Heck reactions.     

Comparison of self-cleaning properties of three titania coatings on float glass

This work compares the self-cleaning properties of experimental TiO₂ and TiO₂-Ag coatings on float glass with a commercial self-cleaning glass. In the experimental surfaces, TiO₂ coating was applied to float glass via the sol-gel route, while TiO₂-Ag coating was applied by the liquid flame spray method, which deposits TiO₂-Ag composite nanoparticles on the surface. The effect of the coatings on the surface wettability and the activation time for achieving hydrophilicity was studied through water contact angle as a function of exposure time to UV light. The surface morphology was investigated by using scanning electron microscopy (SEM) and confocal optical microscopy. The photocatalytic activity of the coatings was examined with methylene blue and stearic acid degradation tests. Finally, the soil attachment to the surfaces was tested with a sebum-based model soil. The sol-gel TiO₂ coating became superhydrophilic within a few hours, while the activation time needed for the commercial titania coated glass was several days. The surface with the TiO₂-Ag nanoparticles did not show any marked changes in the water contact angle. The commercial titania coated and the sol-gel TiO₂ surfaces showed self-cleaning properties and clearly lower attachment of soil than the uncoated and TiO₂-Ag coated surfaces. The difference in the interaction of the surfaces with the organic contaminants was assumed to depend mainly on differences in the thickness of the coatings.     

The effect of MWCNTs on molar mass in in situ polymerization of styrene and methyl methacrylate

Two different in situ-polymerization techniques were studied, emulsion polymerization and combined emulsion/suspension polymerization, with styrene and methyl methacrylate in the presence of different multiwalled carbon nanotubes (MWCNTs). Molar masses and molar mass distributions were determined by size exclusion chromatography, and particle size of the emulsions by dynamic light scattering and rotation rheometry. The compatibility of the MWCNTs and monomer affected polymerization and therefore the molar masses. The MWCNTs stabilized the emulsions, and molar mass distributions narrowed with higher amounts of MWCNTs. In emulsion polymerization of styrene, MWCNTs increased the molar mass. The increase of molar mass was based on the compatible molecular structures of MWCNTs and styrene, so that individual nanotubes were covered by monomer clouds when initiator arrived. In combined emulsion/suspension polymerization of styrene, MWCNTs reacted with the initiator and there was less initiator to polymerize the monomer. There is probably a critical surface area of MWCNTs, for which more initiator is consumed in the reaction with MWCNTs than in polymerization of the monomer. In emulsion polymerization of MMA, monomer clouds around MWCNTs do not form due to incompatible molecular structures, and nanotubes do not enhance polymerization of MMA. In combined polymerization, the initiator is reacting with the nanotubes and the tube is acting as a carrier for initiator, and molar masses are higher.     

Global intercompany assessment of ICIEF platform comparability for the characterization of therapeutic proteins

An international team spanning 19 sites across 18 biopharmaceutical and in vitro diagnostics companies in the United States, Europe, and China, along with one regulatory agency, was formed to compare the precision and robustness of imaged CIEF (ICIEF) for the charge heterogeneity analysis of the National Institute of Standards and Technology (NIST) mAb and a rhPD-L1-Fc fusion protein on the iCE3 and the Maurice instruments. This information has been requested to help companies better understand how these instruments compare and how to transition ICIEF methods from iCE3 to the Maurice instrument. The different laboratories performed ICIEF on the NIST mAb and rhPD-L1-Fc with both the iCE3 and Maurice using analytical methods specifically developed for each of the molecules. After processing the electropherograms, statistical evaluation of the data was performed to determine consistencies within and between laboratory and outlying information. The apparent isoelectric point (pI) data generated, based on two-point calibration, for the main isoform of the NIST mAb showed high precision between laboratories, with RSD values of less than 0.3% on both instruments. The SDs for the NIST mAb and the rhPD-L1-Fc charged variants percent peak area values for both instruments are less than 1.02% across different laboratories. These results validate the appropriate use of both the iCE3 and Maurice for ICIEF in the biopharmaceutical industry in support of process development and regulatory submissions of biotherapeutic molecules. Further, the data comparability between the iCE3 and Maurice illustrates that the Maurice platform is a next-generation replacement for the iCE3 that provides comparable data.