The Stability of Graded Multiplicity in the Setting of the Kostant-Rallis Theorem

From a combinatorial point of view, we approach the problem of finding a graded generalization of the Kostant-Rallis theorem concerning the K-harmonic polynomials on p. Specifically, for each classical symmetric pair we obtain a stable range where the multiplicity of an irreducible K-representation in the degree d harmonic polynomials can be expressed in terms of Littlewood-Richardson coefficients.     

Unconventional titania photocatalysis: direct deployment of carboxylic acids in alkylations and annulations

Under dry, anaerobic conditions, TiO(2) photocatalysis of carboxylic acid precursors resulted in carbon-carbon bond-forming processes. High yields of dimers were obtained from TiO(2) treatment of carboxylic acids alone. On inclusion of electron-deficient alkenes, efficient alkylations were achieved with methoxymethyl and phenoxymethyl radicals. In reactions with maleic anhydride or maleimides, phenoxyacetic acid produced chromenedione derivatives in addition to adducts. These photocatalytic reactions are simple and cheap to perform, and the TiO(2) is easily removed by filtration. The anaerobic photocatalysis strategy offers a range of synthetic possibilities.     

Quantitative reagent-free detection of fibrinogen levels in human blood plasma using Raman spectroscopy

Fibrinogen assays are commonly used as part of clinical screening tests to investigate haemorrhagic states, for detection of disseminated intravascular coagulation and as a predictor of a variety of cardiovascular events. The Clauss assay, which measures thrombin clotting time, is the most commonly used method for measuring fibrinogen levels. Nevertheless, inconsistencies are present in inter-manufacturer reagent sources, calibration standards and methodologies. Automated coagulation analysers, which measure changes in optical density during the prothrombin time (PT-Fg), have found use in many hospitals. However, the PT-Fg method is found to give falsely elevated values due to varying choices of calibrants, reagents and analysers. As an alternative, Raman spectroscopy has previously been applied to the analysis of blood and its various constituents to determine various analyte concentrations such as glucose, urea, triglycerides and cholesterol. In this study, Raman spectroscopy was investigated for its ability to accurately quantify fibrinogen concentration in blood plasma. Samples collected from 34 patients were analysed by Raman spectroscopy and the resultant spectra were fitted with a Partial Least Squares Regression model using target values obtained through a pre-calibrated Clauss fibrinogen assay. Various spectral pre-processing methods were utilised to prepare data to be entered into a calibration model. A root mean square error of prediction of 0.72 ± 0.05 g/L was achieved with as few as 25 spectra. In this pilot study, Raman spectroscopy has been demonstrated to be a robust technique providing rapid and reagent-free quantification of fibrinogen levels in blood plasma and a potential alternative to the Clauss assay.     

Carbohydrate-derived hydrothermal carbons: a thorough characterization study

Hydrothermal carbonization (HTC) is an aqueous-phase route to produce carbon materials using biomass or biomass-derived precursors. In this paper, a comprehensive physicochemical and textural characterization of HTC materials obtained using four different precursors, namely, xylose, glucose, sucrose, and starch, is presented. The development of porosity in the prepared HTC materials as a function of thermal treatment (under an inert atmosphere) was specifically monitored using N(2) and CO(2) sorption analysis. The events taking place during the thermal treatment process were studied by a combined thermogravimetric/infrared (TGA-IR) measurement. Interestingly, these inexpensive biomass-derived carbon materials show good selectivity for CO(2) adsorption over N(2) (CO(2)/N(2) selectivity of 20 at 273 K, 1 bar and 1:1 gas composition). Furthermore, the elemental composition, morphologies, degree of structural order, surface charge, and functional groups are also investigated.     

Influence of bridging atom on the vertical phase separation of low band gap bulk heterojunction solar cells

Vertical phase separation of the polymer and fullerene molecules in bulk heterojunction organic solar cells influences the exciton dissociation, charge carrier transport and collection. This work compares the vertical phase separation of poly[2,1,3‐benzothiadiazole‐4,7‐diyl[4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl]] (C‐PCPDTBT):[6,6]‐phenyl C71 butyric acid methyl ester (PC₇₁BM) and poly[2,1,3‐benzothiadiazole‐4,7‐diyl[4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b:3,4‐b′]dithiophene‐siloe2,6‐diyl]] (Si‐PCPDTBT):PC₇₁BM blend films, using X‐ray photoemission spectroscopy depth profiles. The difference between the two polymers is the bridging atom, which is carbon for C‐PCPDTBT and silicon for Si‐PCPDTBT. Si‐PCPDTBT exhibits enhanced polymer chain packing and crystallinity. We believe this enhanced chain packing provides a driving force during film drying which alters the vertical morphology. The different nature of vertical phase separation plays a role in determining the increased device performance observed for Si‐PCPDTBT:PC₇₁BM solar cells. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Characterisation of the transparent surface coatings on post-Byzantine icons using microscopic, mass spectrometric and spectroscopic techniques

Icons are frequently covered with superimposed transparent layers of varnish and glaze that often obscure their image and disrupt their study and conservation treatment. Using a combination of microscopic, mass spectrometric and spectroscopic techniques, a micro-analytical methodology was developed for the characterisation of these surface coatings. More specifically, light microscopy (LM), electron ionisation direct temperature resolved mass spectrometry (EI-DTMS), pyrolysis gas chromatography mass spectrometry (Py-GC/MS), imaging Fourier transform infrared spectroscopy (imaging-FTIR) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were used to investigate the coatings present on the surface of five Greek post-Byzantine icons. The results showed that the aged layers of varnish and glaze contain various mixtures of materials, including diterpenoid (DTP) and triterpenoid (TTP) resins, linseed oil, lead-containing dryers, egg, and beeswax. This study also elucidated issues regarding the initial application and the later interventions on those coatings, their interaction with each other, as well as some effects observed on the underlying paint layers.