Evidence for the surface-catalyzed suzuki-miyaura reaction over palladium nanoparticles:an operando XAS study

No need to get away: X-ray absorption spectroscopy of catalytically active palladium nanopartlcles during a SuzukiMlyaura cross-coupling reaction revealed that the nanopartlcles were stable under the reaction conditions, and that cross-coupling Involved the direct participation of surface palladium defect sites In the catalytic cycle (see picture). Selective chemical and structural poisons provided further evidence for a heterogeneous active site. © 2010 Wiley-VCH Verlag GmbH & Co. KCaA.

Operando synchronous DRIFTS/MS/XAS as a powerful tool for guiding the design of Pd catalysts for the selective oxidation of alcohols

The selective aerobic oxidation of crotyl alcohol to crotonaldehyde was investigated by time-resolved synchronous DRIFTS/MS/XAS over silica and alumina supported Pd nanoparticles. Alcohol and oxygen reactant feeds were cycled through the catalyst bed while dynamic measurements of the palladium oxidation state, molecular adsorbates and evolved product distribution were made simultaneously on a sub-second timescale. Highly dispersed palladium nanoparticles remained in a partially oxidised state

Surface catalysed Suzuki-Miyaura cross-coupling by Pd nanoparticles:an operando XAS study

Size-controlled, catalytically active PVP-stabilised Pd nanoparticles have been studied by operando liquid phase XAS during the Suzuki cross-coupling of iodonanisole and phenylboronic acid in MeOH-toluene using KOMe base. XAS reveals nanoparticles are stable to metal leaching throughout the reaction, with surface density Pd defect sites directly implicated in the catalytic cycle. The efficacy of popular selective chemical and structural poisons for distinguishing heterogeneous and homogeneous contributions in Pd catalysed cross-couplings is also explored. © 2010 The Royal Society of Chemistry.

Ambulatory EEG monitoring in the diagnosis and treatment of epilepsy and related disorders

Ambulatory EEG recording enables patients with epilepsy and related disorders to be monitored in an unrestricted environment for prolonged periods. Attacks can therefore be recorded and EEG changes at the time can aid diagnosis. The relevant Iiterature is reviewed and a study made of' 250 clinical investigations. A study was also made of the artefacts,encountered during ambulatory recording. Three quarters of referrals were for distinguishing between epileptic and non-epileptic attacks. Over 60% of patients showed no abnormality during attacks. In comparison with the basic EEG the ambulatory EEG provided about ten times as much information. A preliminary follow-up study showed that results, of ambulatory monitoring agreed with the final diagnosis in 8 of 12 patients studied. Of 10 patients referred, for monitoring the occurrence of absence seizures, 8 showed abnormality during the baslcJ EEG .and 10 during the ambulatory EEG. Other patients. were referred: for sleep recording and to clarify the seizure type. An investigation into once daily (OD) versus twice daily administration of sodium valproate in patients with absence seizures showed that an OD regime was equally as effective as a BD regime. Circadian variations in spike and wave activity in patients on and off treatment were also examined. There was significant agreement between subjects on the time of occurrence of abnormality during sleep only, This pattern was not ,affected with treatment nor was there any difference in the daily pattern of occurrence of abnormality between the two regimes. Overall findings suggested that ambulatory monitoring was a valuable tool in the diagnosis and treatment of epilepsy which with careful planning and patient selection could be used in any EEG department and would benefit a:wide range of patients.

Mechanisms of drying of particulate slurries

The literature on the evaporation of pure liquid drops and the drying of drops of solutions and slurries has been reviewed with particular reference to spray drying. A 0.1-0.2 mm glass filament-thermocouple was constructed and used to study simultaneously, heat and mass transfer from a single suspended drop placed in a humidity and temperature controlled, 28 mm OD vertical wind tunnel. Heat conduction through the filament was minimised eg at 100¦C it accounted for only 9.3% of the total heat transferred to a drop. Evaporation of single water drops was also studied in a 101 mm OD vertical wind tunnel. The Nusselt number was found to be a function of the Reynolds, Prandtl and Transfer number over an air temperature range of 17¦C to 107¦C. The proposed correlation is: Nu = 2+(-12.96B+0.76)Re¦-5Pr0-33 Experimental drying studies were carried out on single suspended 1 to 2.5 mm diameter drops of aqueous sodium sulphate decahydrate, sodium chloride, potassium sulphate, copper sulphate and sodium acetate solutions and slurries at temperatures of 20¦C to 124¦C. Dried crusts were examined by Scanning Electron Microscopy. The drying history of any material depended upon the nature of the crust formed. Sodium acetate formed a non-rigid skin prior to the formation of a rigid crust. A modified receding evaporation interface model was proposed for the drying of solutions and slurries. This covered both the constant rate period prior to crust formation and the subsequent falling rate period. The model was solved numerically for the variation in core temperature, drop weight and crust thickness. Good agreement was obtained between model predictions and experimental results for materials forming rigid crusts i.e. sodium sulphate decahydrate, sodium chloride, potassium sulphate and copper sulphate. However, the drying histories of drops of 10-20% weight initial concentration sodium acetate were unpredictable since formation of a non-rigid skin deviated from the model assumption of a rigid outer surface. At higher initial concentrations (40% weight) where a rigid crust was formed for sodium acetate, good agreement was obtained between experimental results and model predictions. Single suspended drop studies are concluded to provide a valuable insight into the drying mechanisms of specific solutions and slurries.

Optic disc haemorrhage audit

Poster section INTRODUCTION. Retrospective Analysis PURPOSE. To evaluate the morphology and location of optic disc haemorrhages (ODH) identified at diabetic retinopathy (DR) screening to establish whether particular ODH are predictive of ocular disease (e.g. glaucoma). METHODS. Retrospective analysis of 77 patients who presented with ODH at DR screening in the Birmingham and Black Country screening programme between June 2009-March 2010. Mean age was 71 years (range 39-89). Cup/disc ratio (CDR), location and morphology of the haemorrhage were recorded. The outcome of the referral and the status of the ODH were followed up a year later. RESULTS. Of the 77 referred, 34 patients were unassessed for possible glaucoma. Of the 43 patients that were assessed in the hospital eye service for glaucoma, 11 (26%) were diagnosed with glaucoma. These glaucoma patients mostly presented with flame haemorrhages (64%) and blot haemorrhages (36%). Haemorrhages tended to adjoin the margin of the OD (64%), and were more commonly flame shaped (64%). They less commonly occurred in the optic disc itself (36%), and were all blot shaped. The OD Cup/disc ratio (CDR) of the patients with glaucoma (n=11) ranged from 0.33-0.57. It is interesting to note the highest CDR was 0.68 in the 77 patients referred. 32 patients were confirmed as not having glaucoma. 24 (75%) of these patients presented with an ODH adjoining the margin, of which 20 (83%) were flame, and 4 blot (17%) shaped. Only 8 (25%) presented with an ODH in the OD, of which 6 (75%) were blot shaped. One year follow up of the 77 referred cases revealed that the ODH resolved in 45 (57%) patients while 10 (13%) still had an ODH present. 15 (21%) were still under ophthalmology hence digital retinal photos were not available for assessment. Six patients (8%) (age range 71-91 years) died within the year, and one lost to follow up. CONCLUSIONS. The results suggest that a significant number of patients with ODH have glaucoma and that the differing morphology of the haemorrhage is not a major predictor i.e. blot versus flame shaped, adjoining or in the optic disc. The cup/disc ratio did not predict glaucoma either.

Wybór w gospodarce:wprowadzenie do ekonomii

Wybór w gospodarce. Wprowadzenie do ekonomii to nowe, rozszerzone, czwarte wydanie opublikowanego po raz pierwszy na poczatku lat 90. ubieglego wieku i dwukrotnie wznawianego popularnego i cenionego podrecznika akademickiego, którego poprzednie wydania rozeszly sie w nakladzie blisko 5,000 egzemplarzy. Stanowi on zwiezly i przejrzysty wyklad z podstaw ekonomii (mikroekonomii), rozszerzony o analize instytucjonalna. Autor publikacji podjal wysilek powiazania ze soba poszczególnych problemów tak, aby uwypuklic proces myslenia ekonomicznego, skoncentrowany wokól jednej podstawowej idei: spójne preferencje pozwalaja okreslic uzytecznosc poszczególnych dóbr, co w polaczeniu ze zjawiskiem rzadkosci zasobów prowadzi do okreslenia ich kosztu alternatywnego w procesie produkcji i wymiany. Z kolei rola instytucji polega na minimalizowaniu kosztów transakcyjnych procesów ekonomicznych, w szczególnosci przez zapewnienie stabilnych praw wlasnosci. Podrecznik zawiera wiele przykladów ilustrujacych poszczególne zagadnienia, a nacisk jest polozony nie na przekazywanie maksimum oderwanych od siebie informacji, lecz na konstruowanie rozumowan, analize i wyciaganie wniosków. Intencja autora jest skupienie sie na mniejszej liczbie kluczowych zagadnien, przedstawionych jednakze w miare dokladnie i w powiazaniu ze soba. Kazdy rozdzial jest zbudowany wokól kilku podstawowych twierdzen, które sa uzasadniane intuicyjnie, a w pewnych przypadkach równiez formalnie. Podrecznik jest adresowany nie tylko do studentów i wykladowców uczelni ekonomicznych, ale takze sluchaczy innych kierunków studiów, chcacych opanowac w krótkim czasie podstawowe narzedzia analizy ekonomicznej. Podrecznik dzieli sie na dwie czesci. Rozdzialy od pierwszego do trzeciego zawieraja zagadnienia podstawowe (takie, jak rzadkosc, racjonalny wybór, krzywa mozliwosci produkcyjnych, specjalizacja i wymiana), niezbedne do naszkicowania w rozdziale czwartym prostego obrazu mechanizmu cenowo-rynkowego. Rozdzial piaty przedstawia pojecie efektywnosci ekonomicznej, zagadnienia dóbr publicznych i efektów zewnetrznych i na ich tle ujmuje charakterystyke dzialania rzadu, wykorzystujac elementy ekonomicznej teorii wyboru publicznego. Druga czesc ksiazki zawiera systematyczna analize zachowan dwóch podstawowych podmiotów wystepujacych na rynku: konsumenta i przedsiebiorcy. Rozdzialy szósty i siódmy omawiaja zagadnienia zwiazane z maksymalizacja uzytecznosci i wyborem konsumenta, a rozdzial ósmy kwestie wyboru technologii oraz dzialania producenta minimalizujacego koszty. Wykorzystujac charakterystyke kosztów zawartych w rozdziale ósmym, autor przechodzi nastepnie do omówienia modeli dzialania przedsiebiorstwa w róznym otoczeniu rynkowym. Rozdzial dziewiaty przedstawia typowa sytuacje konkurencyjna, a rozdzial dziesiaty przedsiebiorstwo majace wplyw na cene.

Reaction-driven surface restructuring and selectivity control in allylic alcohol catalytic aerobic oxidation over Pd

Synchronous, time-resolved DRIFTS/MS/XAS cycling studies of the vapor-phase selective aerobic oxidation of crotyl alcohol over nanoparticulate Pd have revealed surface oxide as the desired catalytically active phase, with dynamic, reaction-induced Pd redox processes controlling selective versus combustion pathways.

Identifying the active phase in Cs-promoted MgO nanocatalysts for triglyceride transesterification

Background: Biodiesel is a clean-burning, renewable and biodegradable diesel fuel substitute derived from animal fats and plant oils, which may play an important role in replacing diminishing fossil fuel reserves and combating climate change. Conventional biodiesel production uses soluble base catalysts, such as Na or K alkoxides, to convert oils into fuel, and as a result requires energy intensive aqueous quench cycles to isolate the biodiesel product. Results: Cs-doping nanoparticulate MgO, prepared via a novel, supercritical sol-gel method, yields a solid base catalyst with improved activity for the transesterification of pure triacylglycerides (TAGs) and olive oil. Conclusion: Here, X-ray absorption spectroscopy (XAS) is used to probe the local chemical environment of Cs atoms in order to identify the nature of the catalytically active species as CsMg(CO)(HO). © 2013 Society of Chemical Industry.

A fuzzy decision tree-based duration model for Standard Yorùbá text-to-speech synthesis

In this paper, we present syllable-based duration modelling in the context of a prosody model for Standard Yorùbá (SY) text-to-speech (TTS) synthesis applications. Our prosody model is conceptualised around a modular holistic framework. This framework is implemented using the Relational Tree (R-Tree) techniques. An important feature of our R-Tree framework is its flexibility in that it facilitates the independent implementation of the different dimensions of prosody, i.e. duration, intonation, and intensity, using different techniques and their subsequent integration. We applied the Fuzzy Decision Tree (FDT) technique to model the duration dimension. In order to evaluate the effectiveness of FDT in duration modelling, we have also developed a Classification And Regression Tree (CART) based duration model using the same speech data. Each of these models was integrated into our R-Tree based prosody model. We performed both quantitative (i.e. Root Mean Square Error (RMSE) and Correlation (Corr)) and qualitative (i.e. intelligibility and naturalness) evaluations on the two duration models. The results show that CART models the training data more accurately than FDT. The FDT model, however, shows a better ability to extrapolate from the training data since it achieved a better accuracy for the test data set. Our qualitative evaluation results show that our FDT model produces synthesised speech that is perceived to be more natural than our CART model. In addition, we also observed that the expressiveness of FDT is much better than that of CART. That is because the representation in FDT is not restricted to a set of piece-wise or discrete constant approximation. We, therefore, conclude that the FDT approach is a practical approach for duration modelling in SY TTS applications. © 2006 Elsevier Ltd. All rights reserved.

Intonation contour realisation for Standard Yorùbá text-to-speech synthesis:a fuzzy computational approach

This paper presents a novel intonation modelling approach and demonstrates its applicability using the Standard Yorùbá language. Our approach is motivated by the theory that abstract and realised forms of intonation and other dimensions of prosody should be modelled within a modular and unified framework. In our model, this framework is implemented using the Relational Tree (R-Tree) technique. The R-Tree is a sophisticated data structure for representing a multi-dimensional waveform in the form of a tree. Our R-Tree for an utterance is generated in two steps. First, the abstract structure of the waveform, called the Skeletal Tree (S-Tree), is generated using tone phonological rules for the target language. Second, the numerical values of the perceptually significant peaks and valleys on the S-Tree are computed using a fuzzy logic based model. The resulting points are then joined by applying interpolation techniques. The actual intonation contour is synthesised by Pitch Synchronous Overlap Technique (PSOLA) using the Praat software. We performed both quantitative and qualitative evaluations of our model. The preliminary results suggest that, although the model does not predict the numerical speech data as accurately as contemporary data-driven approaches, it produces synthetic speech with comparable intelligibility and naturalness. Furthermore, our model is easy to implement, interpret and adapt to other tone languages.

Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation

Ultrathin alumina monolayers grafted onto an ordered mesoporous SBA-15 silica framework afford a composite catalyst support with unique structural properties and surface chemistry. Palladium nanoparticles deposited onto Al-SBA-15 via wet impregnation exhibit the high dispersion and surface oxidation characteristic of pure aluminas, in conjunction with the high active site densities characteristic of thermally stable, high-area mesoporous silicas. This combination confers significant rate enhancements in the aerobic selective oxidation (selox) of cinnamyl alcohol over Pd/Al-SBA-15 compared to mesoporous alumina or silica supports. Operando, liquid-phase XAS highlights the interplay between dissolved oxygen and the oxidation state of palladium nanoparticles dispersed over Al-SBA-15 towards on-stream reduction: ambient pressures of flowing oxygen are sufficient to hinder palladium oxide reduction to metal, enabling a high selox activity to be maintained, whereas rapid PdO reduction and concomitant catalyst deactivation occurs under static oxygen. Selectivity to the desired cinnamaldehyde product mirrors these trends in activity, with flowing oxygen minimising CO cleavage of the cinnamyl alcohol reactant to trans-β-methylstyrene, and of cinnamaldehyde decarbonylation to styrene. © 2013 Elsevier B.V.

Dynamic restructuring of Pd nanoparticles and single crystals during catalytic selective alcohol oxidation

The aerobic selective oxidation (selox) of alcohols represents an environmentally benign and atom efficient chemical valorisation route to commercially important allylic aldehydes, such as crotonaldehyde and cinnamaldehyde, which find application in pesticides, fragrances and food additives. Palladium nanoparticles are highly active and selective heterogeneous catalysts for such oxidative dehydrogenations, permitting the use of air (or dioxygen) as a green oxidant in place of stoichiometric chromate permanganate saltsor H2O2. Here we discuss how time-resolved, in-situ X-ray spectroscopies (XAS and XPS) reveal dynamic restructuring of dispersed Pd nanoparticles and Pd single-crystals in response to changing reaction environments, and thereby identify surface PdO as the active species responsible for palladium catalysed crotyl alcohol selox (Figure 1); on-stream reduction to palladium metal under oxygen-poor regimes thus appears the primary cause of catalyst deactivation. This insight has guided the subsequent application of surfactant-templating and inorganic nanocrystal methodologies to optimize the density of desired active PdO sites for the selective oxidation of natural products such as sesquiterpenoids.