bluuebunny/crossref_metadata_2025 huggingface dataset:
Power Doppler ultrasound of rheumatoid synovitis: quantification of therapeutic response
Authors: Teh J , Stevens K , Williamson L , Leung J , McNally E G
Published: January 2004

The aim of this study is to quantify power Doppler assessment of therapeutic response in rheumatoid synovitis. 13 patients (6 male, 7 female) with rheumatoid arthritis, who had an acute exacerbation of small joint synovitis in the hands, were examined with quantitative power Doppler, before and after intravenous corticosteroid treatment. All patients were examined by a single radiologist, using an ATL HDI 5000 ultrasound machine (ATL, Boswell). The images were analysed using a specially developed software package (HDI Lab), which quantifies power Doppler signal. All patients improved clinically following treatment, which was reflected in functional disability scores, and in the C-reactive protein levels and erythrocyte sedimentation rate. In all cases, there was a significant decrease in synovial vascularity as measured by the mean amplitude of signal on quantitative power Doppler. Quantitative power Doppler may allow objective assessment of treatment in small joint synovitis.
Lower moiety pelvic-ureteric junction obstruction (PUJO) of the duplex kidney presenting with pyonephrosis in adults
Authors: Wah T M , Weston M J , Irving H C
Published: January 2004

The most common congenital abnormality of the urinary tract is a duplex kidney. Pelvic-ureteric junction obstruction (PUJO) is a rare association that can affect the lower moiety of incomplete duplex kidneys. We report two adult cases of PUJO of the lower moiety in a duplex kidney that both presented with pyonephrosis. This late presentation of lower moiety PUJO with pyonephrosis has not been described previously. We describe the imaging appearances of this rare association and highlight this important diagnostic consideration in lower moiety hydronephrosis of the adult patient.
Evaluation of the Commission of the European Communities quality criteria for the paediatric lateral spine
Authors: Offiah A C , Hall C M
Published: January 2004

The study aimed to evaluate the Commission of the European Communities (CEC) quality criteria for paediatric lateral spine radiographs, and to use these to assess and compare the quality of film–screen and digital images. 286 paediatric lateral spine radiographs (89 film–screen and 197 digital) were independently analysed by two observers according to the CEC criteria. Based on fulfilment of criteria, images were assigned two scores, an image criteria score and a visual grading analysis score. Sensitivity values (S) on digital radiographs were recorded and correlated with image quality. Variability for assignment of scores between observers was lower for the image criteria than the visual grading analysis technique. Analysis of variance for fulfilment of criteria between techniques, and (for digital images) age and sensitivity values was calculated. Film–screen did significantly better (p<0.05) than digital imaging for Criterion 6 (visually sharp reproduction of the cortex and trabecular markings consistent with age), but significantly worse for Criterion 7 (reproduction of the adjacent soft tissues). There was a significant difference in mean S values for each age group when Criterion 6 was or was not met. Results show that although interpretation between two observers was ambiguous, the CEC criteria were able to detect differences in quality of film–screen and digital images. It is also possible to use them when optimizing target S values.
A retrospective study of bladder morbidity in patients receiving intracavitary brachytherapy as all or part of their treatment for cervix cancer
Authors: Wilkinson J M , Harris M A , Davidson S E , Welch R S , Hunter R D , Swindell R
Published: January 2004

A retrospective study has been undertaken in an attempt to identify physical parameters that could confidently be used to predict an enhanced risk of bladder morbidity following intracavitary brachytherapy. 366 women received brachytherapy as all, or part, of their treatment for cervical cancer at the Christie Hospital in 1990 and 1991, and of these, 60 patients developed identifiable bladder morbidity (graded on a scale of 1–4 using the Franco-Italian glossary). These were age and stage matched with 60 asymptomatic women who were also treated for cervical cancer by brachytherapy during the same time period. The sizes of applicators used in the two groups were noted and compared. The two groups were also compared with respect to the heights of the applicator set above the symphysis pubis, the degree of anteversion or retroversion of the applicator sets and where possible, the doses at the International Commission on Radiation Units and Measurements (ICRU) bladder reference point. Where CT scans of the applications were available, these were reviewed to see if any differences in the size, shape or location of the bladder were apparent. No significant difference was found between the two groups of patients for any of the parameters investigated. The physical factors investigated in this study cannot be used to reliably predict bladder complications. There was a significant correlation between bladder morbidity and morbidity in other pelvic sites.
Diffusion-weighted MRI and ADC mapping in FK506 neurotoxicity
Authors: Ahn K J , Lee J W , Hahn S T , Yang D W , Kim P S , Kim H J , Kim C C
Published: January 2004

FK506 is a newly developed potent immunosuppressant for preventing rejection after organ transplantation. However, FK506 can induce central nervous system toxicity. Until now the pathogenic mechanism of FK506 neurotoxicity was unclear. We report the findings of diffusion-weighted MRI and apparent diffusion coefficient (ADC) mapping of a FK506 neurotoxicity patient who showed increased signal intensities in both parieto-occipital lobes on T  2 weighted images, diffusion-weighted images and ADC maps. These findings suggest that a vasogenic oedema rather than a cytotoxic oedema may play a pivotal role in FK506 neurotoxicity pathogenesis.
A generic computer program for checking photon beam dose calculations
Authors: Redpath A T
Published: January 2004

A computer program for checking photon external beam dose calculations is described. It provides a check of the treatment planning calculation by the use of machine data that are independent of that used in the initial calculation. Data required to specify any radiation beam are easily and rapidly set up and the program works for all the major manufacturers' machines. The user interface uses an interactive screen for machine data input and also for dose checking, where dose calculation is performed in real time as data are entered. The dose resulting from the planned field parameters is calculated and compared with the prescribed dose with a warning provided if the agreement is outside a set range (±5%). Its purpose is to act as a final quality assurance check to ensure that no significant errors occur in the monitor unit calculation.
Calcification in coronary arteries as quantified by CT scans correlated with tobacco consumption in patients with inoperable non-small cell lung cancer treated with three-dimensional radiotherapy
Authors: Milker-Zabel S , Zabel A , Manegold C , Zuna I , Wannenmacher M , Debus J
Published: January 2004

It has been shown that radiological manifestations of coronary artery sclerosis are an indirect measure of co-morbidity and predictive of survival. The aim of the present study is to evaluate the outcome and side effects after three-dimensional (3D) radiotherapy in patients with unresectable non-small cell lung cancer (NSCLC) stage I, II and IIIA, depending on coronary artery calcification, Karnofsky performance index (KI) and co-morbidity. Between 1993 and 1999, 89 patients with unresectable NSCLC were treated with 3D-radiotherapy. The median age was 66.6 years and median KI 80%. All patients had 3D-treatment planning, based on CT scans. The median total dose was 60 Gy in 2 Gy fractions five times a week. The mean follow-up period was 13.2 months and mean survival time 12.2 months. Significant prognostic factors for improved survival were KI and tumour stage. Patients with a KI<90% had a median survival of 6.5 months compared with 14 months, in patients with KI≥90% (p<0.001). NSCLC stage I+II showed a significantly longer median survival than patients with NSCLC stage IIIA (16.5 months versus 7 months, p<0.004). A significant correlation was seen between pack-years and coronary artery calcification (p<0.05) and between age and marked coronary artery calcification. The incidence of calcification was 67% in smokers (≥20 pack-years) and 43/58 in patients >60 years (p<0.007). Side effects, e.g. pneumonitis, did not correlate with coronary artery calcification but correlated with chronic obstructive lung disease in 19/89 patients. Conventional CT scans for 3D-treatment planning are able to detect coronary artery calcification. There is a significant correlation between age, KI, tobacco consumption and vascular calcification. Although there was a trend to worse overall survival, coronary artery calcification was not a significant predictor of progression-free and overall survival.
Small “indeterminate” lesions on CT of the liver: a follow-up study of stability
Authors: Robinson P J , Arnold P , Wilson D
Published: January 2004

Distinguishing between small benign malformations in the liver and early metastatic disease remains difficult. We identified a group of 115 patients with known or suspected malignant disease who had “indeterminate” small liver lesions and who underwent 2–16 CT examinations (median 5) over a follow up period of 6–60 months (median 16). The size, shape, edge, homogeneity and attenuation of each of these lesions was assessed. The lesions were classified by their behaviour on follow up CT as either stable (79%) or unstable (21%). The unstable lesions (n=62) included 37 that grew larger and 25 that became smaller or disappeared in patients undergoing anti-tumour therapy. Image features predictive of stable behaviour were small size and sharp edge. Heterogeneity and soft tissue attenuation were significantly associated with unstable behaviour, but these features were seen in only a small minority of cases. Shape had no predictive value. A logistic regression model was constructed based on size and edge to allow an estimate to be made of the likelihood of an individual lesion being unstable. In patients with known or suspected malignant disease, the majority of isolated small liver lesions found on CT are benign. Although size under 5 mm and a sharp margin are favourable features, this appearance does not exclude malignancy.
Valuing Customers
Authors: Gupta Sunil , Lehmann Donald R. , Stuart Jennifer Ames
Published: January 2004

It is increasingly apparent that the financial value of a firm depends on off-balance-sheet intangible assets. In this article, the authors focus on the most critical aspect of a firm: its customers. Specifically, they demonstrate how valuing customers makes it feasible to value firms, including high-growth firms with negative earnings. The authors define the value of a customer as the expected sum of discounted future earnings. They demonstrate their valuation method by using publicly available data for five firms. They find that a 1% improvement in retention, margin, or acquisition cost improves firm value by 5%, 1%, and .1%, respectively. They also find that a 1% improvement in retention has almost five times greater impact on firm value than a 1% change in discount rate or cost of capital. The results show that the linking of marketing concepts to shareholder value is both possible and insightful.
Dynamic Analysis of Learning in Behavioral Experiments
Authors: Smith Anne C. , Frank Loren M. , Wirth Sylvia , Yanike Marianna , Hu Dan , Kubota Yasuo , Graybiel Ann M. , Suzuki Wendy A. , Brown Emery N.
Published: January 2004

Understanding how an animal's ability to learn relates to neural activity or is altered by lesions, different attentional states, pharmacological interventions, or genetic manipulations are central questions in neuroscience. Although learning is a dynamic process, current analyses do not use dynamic estimation methods, require many trials across many animals to establish the occurrence of learning, and provide no consensus as how best to identify when learning has occurred. We develop a state-space model paradigm to characterize learning as the probability of a correct response as a function of trial number (learning curve). We compute the learning curve and its confidence intervals using a state-space smoothing algorithm and define the learning trial as the first trial on which there is reasonable certainty (>0.95) that a subject performs better than chance for the balance of the experiment. For a range of simulated learning experiments, the smoothing algorithm estimated learning curves with smaller mean integrated squared error and identified the learning trials with greater reliability than commonly used methods. The smoothing algorithm tracked easily the rapid learning of a monkey during a single session of an association learning experiment and identified learning 2 to 4 d earlier than accepted criteria for a rat in a 47 d procedural learning experiment. Our state-space paradigm estimates learning curves for single animals, gives a precise definition of learning, and suggests a coherent statistical framework for the design and analysis of learning experiments that could reduce the number of animals and trials per animal that these studies require.
Inactivation of Calcium-Binding Protein Genes Induces 160 Hz Oscillations in the Cerebellar Cortex of Alert Mice
Authors: Cheron Guy , Gall David , Servais Laurent , Dan Bernard , Maex Reinoud , Schiffmann Serge N.
Published: January 2004

Oscillations in neuronal populations may either be imposed by intrinsically oscillating pacemakers neurons or emerge from specific attributes of a distributed network of connected neurons. Calretinin and calbindin are two calcium-binding proteins involved in the shaping of intraneuronal Ca2+fluxes. However, although their physiological function has been studied extensively at the level of a single neuron, little is known about their role at the network level. Here we found that null mutations of genes encoding calretinin or calbindin induce 160 Hz local field potential oscillations in the cerebellar cortex of alert mice. These oscillations reached maximum amplitude just beneath the Purkinje cell bodies and are reinforced in the cerebellum of mice deficient in both calretinin and calbindin. Purkinje cells fired simple spikes phase locked to the oscillations and synchronized along the parallel fiber axis. The oscillations reversibly disappeared when gap junctions or either GABAAor NMDA receptors were blocked. Cutaneous stimulation of the whisker region transiently suppressed the oscillations. However, the intrinsic somatic excitability of Purkinje cells recorded in slice preparation was not significantly altered in mutant mice. Functionally, these results suggest that 160 Hz oscillation emerges from a network mechanism combining synchronization of Purkinje cell assemblies through parallel fiber excitation and the network of coupled interneurons of the molecular layer. These findings demonstrate that subtle genetically induced modifications of Ca2+homeostasis in specific neuron types can alter the observed dynamics of the global network.
Differential Calcium-Dependent Modulation of NMDA Currents in CA1 and CA3 Hippocampal Pyramidal Cells
Authors: Grishin Anton A. , Gee Christine E. , Gerber Urs , Benquet Pascal
Published: January 2004

Neuronal Ca2+influx via NMDA receptors (NMDARs) is essential for the development and plasticity of synapses but also triggers excitotoxic cell death when critical intracellular levels are exceeded. Therefore, finely equilibrated mechanisms are necessary to ensure that NMDAR function is maintained within a homeostatic range. Here we describe a pronounced difference in the modulation of NMDA currents in two closely related hippocampal cell types, the CA1 and the CA3 pyramidal cells (PCs). Manipulations that increase intracellular Ca2+levels strongly depressed NMDA currents in CA3 with only minor effects in CA1 PCs. Furthermore, activation of Gq-coupled metabotropic receptors potentiated NMDA currents in CA1 PCs but depressed them in CA3 PCs. Interestingly, the CA3 type modulation of NMDARs could be converted into CA1-like behavior, and vice versa, by increasing Ca2+buffering in CA3 cells or decreasing Ca2+buffering in CA1 cells, respectively. Our data suggest that a differential Ca2+sensitivity of the regulatory cascades targeting NMDARs plays a key role in determining the direction and magnitude of NMDA responses in various types of neurons. These findings may have important implications for NMDA receptor-dependent synaptic plasticity and the differential sensitivity of CA1 and CA3 PCs to NMDAR-dependent ischemic cell death.
Synthesis of Carbon Nanotubes Using Microwave Radiation
Authors: Hong E.H. , Lee K.‐H. , Oh S.H. , Park C.‐G.
Published: January 2004

We report a method for the synthesis of carbon nanotubes (CNTs) by microwave irradiation. CNTs were successfully synthesized by microwave heating of the catalyst loaded on various supports such as carbon black, silica powder, or organic polymer substrates (Teflon and polycarbonate). Microwave (2.45 GHz, 800 W) irradiation used acetylene as a hydrocarbon source, and 3d transition metals and metal sulfides were used as the catalysts. Different carbon yields and morphologies were obtained depending on the reaction conditions. Fibrous nanocarbons—linear or Y‐branched—were observed as well as carbon nanoparticles and amorphous carbon. High‐resolution transmission electron microscopy (HRTEM) revealed that these fibrous nanocarbons are either multiwalled CNTs or graphitic nanofibers (GNFs). This novel method has the potential to grow CNTs virtually on any substrate provided its absorption of microwave energy is small.
Preparation of Hollow Zeolite Spheres and Three‐Dimensionally Ordered Macroporous Zeolite Monoliths with Functionalized Interiors
Authors: Dong A. , Ren N. , Yang W. , Wang Y. , Zhang Y. , Wang D. , Hu J. , Gao Z. , Tang Y.
Published: January 2004

A novel and flexible strategy involving hydrothermal transformation of guest‐incorporated zeolite‐seeded mesoporous silica spheres was proposed to prepare guest‐encapsulated hollow zeolite spheres and three‐dimensionally (3D) ordered macroporous zeolite monoliths. The guest species that were pre‐incorporated into the mesopores of silica spheres could be spontaneously encapsulated inside the formed hollow zeolite shells by consuming silica nutrition of the original mesoporous silica cores during the hydrothermal process. A wide range of guest materials with a size ranging from nanometers to micrometers, e.g., Ag and PdO nanoparticles, and mesoporous spheres of carbon and polymer of micrometer size were successfully encapsulated into both discrete hollow zeolite spheres and 3D ordered macroporous zeolite monoliths. Such materials are expected to find a variety of applications such as catalysis, adsorption, and novel microreactors for their special structures with active species inside and zeolitic porous shell outside.
Polyaniline–Silica Composite Conductive Capsules and Hollow Spheres
Authors: Niu Z. , Yang Z. , Hu Z. , Lu Y. , Han C.C.
Published: January 2004

In this paper, we report on the preparation of monodisperse polyaniline (PANi)–silica composite capsules and hollow spheres on monodisperse core–gel‐shell template particles. An extension of the previously reported inward growth method was used. The samples were self‐stabilized without external additives. The core–gel‐shell particles were prepared by the inward sulfonation of monodisperse polystyrene particles. The introduced sulfonic acid and sulfone groups are responsible for the gel properties. The gel‐shell thickness and core size were synchronously controlled over the whole particle radius range. After aniline (ANi) monomer was preferentially absorbed in the sulfonated polystyrene shell, PANi was formed by polymerization. PANi was doped in situ with a sulfonic acid group to give the capsules a high conductivity. PANi hollow spheres were derived after the polystyrene cores were dissolved: their cavity size and shell thickness were synchronously controlled by using different core–gel‐shell particles. The PANi–silica composite capsules and hollow spheres were therefore prepared by a sol–gel process using tetraethylorthosilicate in the conducting shell. The PANi shell became more robust while maintaining the same conductivity level. Morphological results indicate that the PANi and silica formed a bicontinuous network. Fourier‐transform infrared (FTIR) spectra revealed that the hydrogen bonding in the PANi–gel shell was enhanced after the silica phase was incorporated, which could explain the high conductivity level after the silica phase was added. In a converse procedure, silica capsules and hollow spheres were prepared by a sol–gel process that incorporated tetraethylorthosilicate into the core–gel‐shell templates, which was followed by the absorption and polymerization of aniline in the silica shell thus forming PANi–silica composite capsules and hollow spheres. The silica capsules and hollow spheres thereby became conductive.
Copper‐Assisted Weak Polyelectrolyte Multilayer Formation on Microspheres and Subsequent Film Crosslinking
Authors: Schuetz P. , Caruso F.
Published: January 2004

The formation of weak polyelectrolyte films on planar and spherical supports has recently evoked major interest, as such coatings allow novel material properties to be tunable by pH and salt adjustment of the polyelectrolyte deposition conditions. We report on the build up of multilayers of the weak polyelectrolytes poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) on submicrometer‐sized polystyrene (PS) and silica colloid spheres (∼ 500 nm) with the aid of copper ion templating. The copper ions complex to the carboxylate groups of PAA, facilitating the formation of PAA/PAH multilayers on the particles. Regular growth of the layers on the colloid spheres with each polyelectrolyte deposition step was confirmed by microelectrophoresis, single‐particle light scattering (SPLS), and transmission electron microscopy (TEM), with an average bilayer thickness of ∼ 3 nm. The polyelectrolyte multilayer‐coated particles formed stable colloidal dispersions, with ζ‐potentials ranging from 30 mV (PAH outer layer) and –50 mV (PAA outer layer). Complementary quartz‐crystal microbalance and UV‐vis spectrophotometry studies on PAA/PAH multilayers formed on planar supports were performed to examine the film formation and the role of copper ion binding to the layers. PAA/PAH multilayers formed on colloid particles were also chemically crosslinked by using the activator 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC). The degree of film crosslinking could be readily controlled by varying the concentration of EDC employed. Following solvent decomposition of the template particles coated with crosslinked PAA/PAH multilayers, intact hollow polymer capsules were obtained. These capsules were found to be impenetrable to polystyrene.
Optical and Electronic Contributions in Double‐Heterojunction Organic Thin‐Film Solar Cells
Authors: Hänsel H. , Zettl H. , Krausch G. , Kisselev R. , Thelakkat M. , Schmidt H.‐W.
Published: January 2004

Combinatorial studies of organic thin‐film photovoltaic cells (see Figure) can identify the separate optical and electronic contributions to the photocurrent. A second charge‐transfer zone is proposed to explain the observed augmentation of the short‐circuit current induced by an additional TiO2 layer. The ratio of the exciton diffusion lengths in copper phthalocyanine (CuPc) and a perylene dye (DMPTI) is estimated to be ≈ 8:5.
A Search for New Red Phosphors Using a Computational Evolutionary Optimization Process
Authors: Sohn K.‐S. , Lee J.M. , Shin N.
Published: January 2004

A computational evolutionary optimization process is adopted to screen a Eu3+‐doped alkali earth borosilicate system in an attempt to search for red phosphors with a high luminescent efficiency when excited by soft ultraviolet irradiation. The evolutionary optimization process involves a genetic algorithm and combinatorial chemistry, which was tailored for the development of light‐emitting diode (LED) phosphors. Vertical simulations and an actual synthesis have been carried out in the present investigation, and promising red phosphors for three‐band white LED applications have been obtained.
A Single Photochromic Molecular Switch with Four Optical Outputs Probing Four Inputs
Authors: Tian H. , Qin B. , Yao R. , Zhao X. , Yang S.
Published: January 2004

The fluorescence, including the intensity and emission peaks, and enhanced photochromism of a simple photochromic compound, bis(5‐pyridyl‐2‐methylthien‐3‐yl)cyclopentene (Py‐BTE) can be reversibly regulated by alternating ultraviolet/visible light irradiation and addition of Zn2+ and protons. A new combinational molecular logic switch with four optical outputs responding to four inputs (see Figure) is proposed.
Photosensitive Pentacene Precursor: Synthesis, Photothermal Patterning, and Application in Thin‐Film Transistors
Authors: Afzali A. , Dimitrakopoulos C.D. , Graham T.O.
Published: January 2004

The Diels–Alder adduct of pentacene and N‐sulfinylmethacrylamide is used as a soluble, photopolymerizable precursor of pentacene for fabrication of patterned thin‐film transitors. The Figure shows the optical micrograph of patterned pentacene derived from the exposure of this adduct to UV radiation, followed by development in methanol and annealing at 200 °C for 90 s.
Surface‐Initiated, Enzymatic Polymerization of Biodegradable Polyesters
Authors: Yoon K.R. , Lee K.‐B. , Chi Y.S. , Yun W.S. , Joo S.‐W. , Choi I.S.
Published: January 2004

Enzyme‐catalyzed, ring‐opening polymerization of biodegradable aliphatic polyesters has successfully been applied to surface‐initiated polymerization (see Figure). Using lipase B as a catalyst, a thin film of poly(ϵ‐caprolactone) (PCL) and poly(p‐dioxanone) (PPDX) on a gold substrate (after a formation of self‐assembled monolayers terminating in hydroxyl groups) is formed.
Scanning Probe Studies of Porphyrin Assemblies and Their Supramolecular Manipulation at a Solid–Liquid Interface
Authors: Elemans J.A.A.W. , Lensen M.C. , Gerritsen J.W. , van Kempen H. , Speller S. , Nolte R.J.M. , Rowan A.E.
Published: January 2004

Dynamic self‐assembly and metal–ligand coordination processes of porphyrin hexamers on a solid–liquid interface have been visualized with scanning tunneling microscopy. The organization of these hexamers into stable and highly organized arrays of “edge‐on” or “face‐on” oriented molecules can be controlled by the addition of different ditopic axial ligands (see Figure).
Molecular‐Scale Interface Engineering of TiO2 Nanocrystals: Improve the Efficiency and Stability of Dye‐Sensitized Solar Cells
Authors: Wang P. , Zakeeruddin S.M. , Humphry‐Baker R. , Moser J.E. , Grätzel M.
Published: January 2004

Co‐grafting an amphiphilic polypyridyl ruthenium sensitizer and 1‐decylphosphonic acid on TiO2 semiconductor nanocrystals has resulted in a long‐term thermally stable dye‐sensitized solar cell (see Figure) with higher than 7 % power conversion efficiency. The extraordinary stability of this high‐efficiency device under both thermal stress and light soaking matches the durability criteria for outdoor applications of solar cells.
The Effect of Ultrasound on the Dissolution of Pyrite Ores in Acidic and Fe2(SO4)3 Solutions
Authors: Dogan H.T. , Kurtbas A. , Tekin T.
Published: January 2004

This paper deals with the investigation of the effect of ultrasonic energy on the dissolution of pyrite ores in acidic and Fe2(SO4)3 solution. In the effect of ultrasound on the dissolution at various temperatures was experimentally investigated, while keeping the particle size and the solution concentration constant. The same experimental runs, without using ultrasound, were performed and the results were compared. According to these results, it was observed that ultrasound increased the conversion fraction by approximately 30 % compared with the experimental results without ultrasound.
Cooperation of Ag/Al2O3 and Sn/Al2O3 Catalysts for the Selective Reduction of NO by Propene
Authors: Hao J. , Liu Z. , Fu L. , Zhu T. , Li J. , Cui X.
Published: January 2004

Compared to the Ag/Al2O3 catalyst, a two‐stage catalyst composed of an Ag/Al2O3 layer followed by a Sn/Al2O3 layer shows higher low‐temperature activity and a wider temperature window. Its activity below 350 °C is enhanced in the presence of SO2. Even in the presence of H2O and SO2, the performance of the same catalytic system is still satisfactory.
Effective Diffusivities and Convective Coefficients for CaO‐CaSO4 and CaO‐CaCl2 Pellets
Authors: Akosman C. , Zirekgür N.
Published: January 2004

Diffusion and convective flow in the pores of pellets formed by compressing mixtures of calcined limestone and CaSO4/CaCl2 powders have been studied experimentally by using the single pellet moment technique. The experiments were conducted in a diffusion cell by flowing nitrogen gas (carrier) through both faces of the pellet. Limestone powder was calcined in an atmosphere of N2 at 800 °C and mixed with CaSO4/CaCl2 for diffusion experiments. Effective diffusivity of helium has been estimated by exposing the upper face of the pellet to a pulse of and matching the response peak on the lower face of the pellet with theoretical expressions. The values of the effective diffusivities increased with temperature, but decreased with increasing CaSO4/CaCl2 content in the pellet. The convective flow contribution to the diffusion flux was found to increase with increasing pressure drop across the pellet.
Utilization of Raw and Activated Date Pits for the Removal of Phenol from Aqueous Solutions
Authors: Banat F. , Al‐Asheh S. , Al‐Makhadmeh L.
Published: January 2004

Activated carbons prepared from date pits, an agricultural waste byproduct, have been examined for the adsorption of phenol from aqueous solutions. The activated carbons were prepared using a fluidized bed reactor in two steps; carbonization at 700 °C for 2 hours in N2 atmosphere and activation at 900 °C in CO2 atmosphere. The kinetic data were fitted to the models of intraparticle diffusion, pseudo‐second order, and Lagergren, and followed more closely the pseudo‐second‐order chemisorption model. The isotherm equilibrium data were well fitted by the Freundlich and Langmuir models. The maximum adsorption capacity of activated date pits per Langmuir model was 16 times higher than that of nonactivated date pits. The thermodynamic properties calculated revealed the endothermic nature of the adsorption process. The uptake of phenol increased with increasing initial phenol concentration from10 to 200 ppm and temperature from 25 to 55 °C, and decreased with increasing the solution pH from 4 to 12. The uptake of phenol was not affected by the presence of NaCl salt.
Silo Discharge: Measurement and Simulation of Dynamic Behavior in Bulk Solids
Authors: Böhrnsen J.U. , Antes H. , Ostendorf M. , Schwedes J.
Published: January 2004

This paper deals with the experimental investigation and the numerical simulation of silo discharge processes, including dynamic interactions between the silo filling and the elastic silo walls. The discharge process is described by a system of nonlinear differential equations. Via the Finite Element Method (FEM) based on an EULERian reference frame, the deformation rate, the velocity field, the porosity, and the stress distribution can be calculated without the need of re‐meshing the FE‐grid. To compare simulation results with measured data, the numerical simulation examples are chosen to be similar to an experimental test‐silo of the Institute of Mechanical Process Engineering at the Technical University of Braunschweig. Optical measurement techniques are applied to investigate the flow profile, and load cells on the silo walls register the stress evolution, e.g., a stress peak (switch) moving from the outlet to the transition from hopper to shaft.
Numerical Simulation of Heat Transfer from an Impinging Jet to a Flat Plate
Authors: Hofmann H. , Martin H. , Kind M.
Published: January 2004

Several CFD calculations have been performed in order to assess the ability of common k‐ϵ turbulence models to predict heat transfer in impinging‐jet flow. One focus is on the influence of the wall on the flow, calculated either by applying a logarithmic wall function or by resolving the flow down to the viscous sublayer (two‐zonal model).
SiSiC Corrosion in Combustion Atmospheres
Authors: Otto S. , Walter G.
Published: January 2004

Many thermal treatment processes require a protection or reaction gas atmosphere. The heating is mostly realized with gas‐fired jet heat pipes made of heat‐proof steel and, recently, of silicon‐infiltrated silicon carbide. However, if fuel oil is used instead of gas, this SiSiC jet pipe material is susceptible to corrosion due to impurities in waste gases of fuel oils. Investigations presented aimed at identifying corrosion‐effecting oil components and their influence on SiSiC at high temperatures.
Scale‐up from Mini Plants
Authors: Zlokarnik M.
Published: January 2004

This contribution continues investigation into whether measurements obtained in mini plants are suitable for scaling up technological processes to the industrial scale or not. In examining this, first the fundamentals of scale‐up are briefly introduced and discussed. It is shown which information is necessary for a reliable scale‐up and to what extent this information can be derived from the conditions existing in mini plants.
Solubility of Carbon Dioxide in Aqueous, Salt‐Containing Solutions of Methanol or Acetone
Authors: Jödecke M. , Xia J. , Pérez‐Salado Kamps Á. , Maurer G.
Published: January 2004

The solubility of carbon dioxide in aqueous solutions of methanol and acetone with as well as without the inorganic salt sodium chloride has been investigated experimentally. The experimental results present a database for the development of thermodynamic models to describe the solubility of carbon dioxide in aqueous solutions of organic components.
Management and Reuse of Mathematical Models in the Industrial Design Process
Authors: Eggersmann M. , von Wedel L. , Marquardt W.
Published: January 2004

The use of model‐based methods to support planning, designing, and operating chemical processes and plants has recently gained an increased importance in the daily work of process engineers. The development of mathematical models through the use of standard flow sheet simulation tools requires the expertise of an experienced designer. Therefore, the value of existing models is not limited to the resources required for their development, but also includes value in the form of knowledge about an enterprise's products and production processes. The reuse of existing models and design experiences in order to lower the costs of model development is therefore economically desirable. This report gives an overview of the systematic long‐term management and use of mathematical models. Some motivating scenarios are used to derive the requirements for a model management system and to evaluate existing methods and tools. The results of these example scenarios are then used to guide the development of a model management system. After presenting a prototypical implementation the article concludes with an outlook on the future importance of model management systems.
Mononuclear Mixed β‐Ketoester‐alkoxide Compound of Titanium as a Promising Precursor for Low‐Temperature MOCVD of TiO2 Thin Films
Authors: Bhakta R. , Hipler F. , Devi A. , Regnery S. , Ehrhart P. , Waser R.
Published: January 2004

A monomeric titanium complex suitable for liquid‐injection MOCVD applications is synthesized and its molecular structure is determined by single‐crystal X‐ray diffraction. [Ti(OiPr)2‐(tbaoac)2] (see Figure), (tbaoac) = tertiarybutylacetoacetonate), is a volatile alkoxide‐(beta)diketonate precursor that has a low melting point and very good solubility in common organic solvents.
Copper Penetration into Porous Ultra‐low‐κ Methyl Silsesquioxane during Selective CVD
Authors: Jezewski C. , Lanford W.A. , Senkevich J.J. , Ye D. , Lu T.‐M. , Jin C.
Published: January 2004

Copper is deposited on nanoporous methyl silsesquioxane (MSQ) from Cu(thd)2. The process, which is carried out at 217 °C, well below the thermal decomposition temperature of Cu(thd)2, and in the presence of H2, results in the penetration and accumulation of copper at the interface between the dielectric layer and the substrate. This is demonstrated by both SEM and RBS, which show that significant selective growth takes place inside the dielectric and there is still no detectable deposition on the surface even after 100 nm growth is achieved.
Atomic Layer Deposition of Hafnium Dioxide Films Using Hafnium Bis(2‐butanolate)bis(1‐methoxy‐2‐methyl‐2‐propanolate) and Water
Authors: Kukli K. , Ritala M. , Leskelä M. , Sajavaara T. , Keinonen J. , Jones A.C. , Roberts J.L.
Published: January 2004

HfO2 films were grown by atomic layer deposition (ALD) from a mononuclear Hf(OtBu)2(OCMe2CH2OMe)2 complex and H2O at temperatures in the range 275–400 °C on borosilicate glass and Si(100) substrates. The growth of the densest films was achieved at temperatures above 300 °C. The growth rate was influenced by the thermal decomposition of the Hf precursor. The as‐deposited films were oxides with an O:Hf ratio of 2.0 ± 0.2, although containing large amounts of impurities. Crystalline monoclinic films were grown at temperatures exceeding 325 °C, whereas at lower temperatures the films mostly remained amorphous. On the whole, the refractive index of the films varied between 1.95 and 2.00. The effective permittivities of the dielectrics in Al/HfO2/p‐Si(100) capacitor structures varied between 12 and 14, slightly increasing with growth temperature.
Growth Per Cycle in Atomic Layer Deposition: Real Application Examplesof a Theoretical Model
Authors: Puurunen R.L.
Published: January 2004

In a previous paper, a theoretical model was derived to describe the growth per cycle in atomic layer deposition (ALD) as a function of the chemistry of the growth when compounds are used as reactants. This paper presents examples of how the model can be applied to investigate the mechanisms of real ALD processes. Three processes that represent different classes of compound reactants were selected for study: the trimethylaluminum/water process to grow aluminum oxide, the yttrium 2,2,6,6‐tetramethyl‐3,5‐heptanedionate (thd)/ozone process to grow yttrium oxide, and the titanium tetrachloride/water process to grow titanium dioxide. The results obtained by applying the model were, in general, consistent with the results obtained through separate investigations of the reaction mechanisms. The model was shown to be a useful tool in investigations of the reaction chemistry of real ALD processes.
Pt Thin Film Collectors Prepared by Liquid‐Delivery Metal–Organic CVD Using Pt(C2H5C5H4)(CH3)3 for LiCoO2 Thin Film Cathodes
Authors: Choi W.‐G. , Choi E.‐S. , Yoon S.‐G.
Published: January 2004

Platinum thin film collectors were deposited onto p‐type Si(100) planar and trench substrates by liquid‐delivery metal–organic (LD‐MO) CVD using Pt(EtCp)Me3, Pt(C2H5C5H4)(CH3)3, for microbatteries. The resistivity and root‐mean‐square (rms) roughness of Pt thin films with (111) preferred orientation increased with the increase of both deposition temperature and system pressure. The deposition of Pt thin films was controlled by a gas‐phase mass‐transfer mechanism and Pt thin films deposited at 350 °C showed the lowest resistivity, rms roughness, and the highest step coverage, 57 %, in trench structure. The LiCoO2 cathode films (step coverage = 51 %) deposited on the trench Pt collector showed an increase in discharge capacity of approximately two and half times that of the planar Pt collector. Platinum thin films deposited by LD‐MOCVD have a possible application as collector materials for LiCoO2 thin film cathodes.
Supplementation of oils with oleanolic acid from the olive leaf (olea europaea)
Authors: Guinda Ángeles , Pérez‐Camino Ma Carmen , Lanzón Augusto
Published: January 2004

A method was studied for utilization of olive leaf, which is a byproduct of olive tree pruning and olive oil production. Our strategy involves two stages. The first is a simple procedure for isolating oleanolic acid, a compound with known biological activity. The second stage involves supplementation of different types of oil with this triterpenic acid. Two protocols were used for incorporating this acid into oils, either as a solid or as a solution, at concentrations from 200 to 1000 ppm. Oleanolic acid in the prepared oils was quantified by gas liquid chromatography. At the concentrations analyzed, the oleanolic acid content measured in all oil samples was equal to the amount added (p <0.05). No significant difference was observed (p <0.05) between the two supplementation procedures in any of the oils.
Lubrication properties of trimethylolpropane esters based on palm oil and palm kernel oils
Authors: Yunus Robiah , Fakhru'l‐Razi Ahmadun , Ooi Tian Lye , Iyuke Sunny E. , Perez Joseph M.
Published: January 2004

Due to the global drive towards biodegradable products, trimethylolpropane [2‐ethyl‐2‐(hydroxymethyl)‐1, 3‐propanediol] (TMP) esters based on palm and palm kernel oils were synthesized, their lubrication properties evaluated, and their potential as base stock for biodegradable lubricants assessed. Two types of TMP esters were considered: palm kernel (PKOTE) and palm oil (PPOTE) TMP esters, derived from palm oil and palm kernel methyl esters, respectively. Lubrication properties such as viscosity, viscosity index (VI) and pour point (PP) were determined according to methods of the American Society for Testing and Materials. Wear and friction properties were evaluated using a four‐ball test machine, while oxidative stability was studied with the Penn State Micro‐oxidation thin‐film test. High VI ranges between 170 to 200 were recorded for these base stocks. PP were relatively high, between 4 to —1 °C, but were improved to at least —33 °C in high oleic palm oil TMP esters. The effects of chemical structure and impurities on wear properties and oxidative stability were also studied. The presence of methyl esters was found to improve wear, but hydroxyl groups in mono‐ and diesters had negative effects at high concentrations. Differences in chemical structures of PKOTE and PPOTE were shown to affect friction and wear results. Both base fluids exhibit oxidative stability comparable to other high oleic base fluids.
One step hydroxybromination of fatty acid derivatives
Authors: Eren Tarık , Küsefoğlu Selim H.
Published: January 2004

Hydroxybromination of methyl oleate, oleic acid and new sunflower oil (high oleic), in an acetone/water mixture by a one step reaction using N‐bromosuccinimide, was studied. The yield of bromohydrin products from oleic acid, methyl oleate and sunflower oil were 90%, 78% and 40%, respectively. Reaction products were analyzed by 1H and 13C nuclear magnetic resonance spectroscopy, infrared spectroscopy, gas chromatography, and mass spectrometry. The hydrobromide derivative of new sunflower oil was acrylated and polymerized to a new polymer.
γ‐ and δ‐tocopherols are more effective than α‐tocopherol on the autoxidation of a 10% rapeseed oil triacylglycerol‐in‐water emulsion with and without a radical initiator
Authors: Wagner Karl‐Heinz , Isnardy Bettina , Elmadfa Ibrahim
Published: January 2004

The antioxidative effects of γ‐ and mainly δ‐tocopherol in a multiphase system were hardly considered up to now. The aim of this study was i) to assess the effects and ii) to follow the degradation of α‐, γ‐ and δ‐tocopherol in concentrations of 0.01%, 0.05%, 0.1% and 0.25% during the oxidation of a 10% purified rapeseed oil triacylglycerol‐in‐water emulsion at 40 °C in the dark for 15 wk in a system containing a low oxygen concentration. Oxidation experiments were performed weekly by assessing the formation of hydroperoxides and hexanal, and the stability of the tocopherols was determined using high‐performance liquid chromatography. Storage tests were conducted with and without the addition of 0.01% α, α′‐azoisobutyronitrile (AIBN), which is a known radical initiator. α‐Tocopherol increased the formation of hydroperoxides in both tests as well as the generation of hexanal when the radical initiator was added; furthermore it was the least stable. γ‐Tocopherol delayed the formation of hexanal and prolonged the stability of the emulsion in a dose‐dependant manner. δ‐Tocopherol was the most stable and also the most effective in delaying lipid oxidation in the emulsions. Each concentration that was tested reduced the rate of hydroperoxide and especially hexanal formation. Hexanal was only formed to a slight extent after 15 wk of oxidation in the test with AIBN and the lowest dose of 0.01% δ‐tocopherol. For all tocopherols, strong correlations were found between tocopherol stability and the extent of oxidation. Results suggest that i) mainly δ‐tocopherol, but also γ‐tocopherol even less pronounced, are very good antioxidants in order to stabilize and prolong the shelf life of oil‐in‐water emulsions, ii) the antioxidative effects were intensified with increasing amounts.
Oxidative stability of black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.) and niger (Guizotia abyssinica Cass.) crude seed oils upon stripping
Authors: Ramadan Mohamed Fawzy , Mörsel Jörg‐Thomas
Published: January 2004

Information on stability of edible oils is important for predicting the quality deterioration of the oil during storage and marketing. Stripping of crude oils removes most of non‐triacylglycerol components, including polar lipids and phenolics. Oxidative stability of black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.) and niger (Guizotia abyssinica Cass.) crude and stripped seed oils was investigated and compared. The factors influencing the oxidative stability of different seed oils were also discussed. Oil samples were stored under accelerated oxidation conditions for 21 d. The progress of oxidation at 60 °C was followed by recording the ultraviolet absorptivity and measuring the formation of oxidative products (peroxide and p‐anisidine values). Inverse relationships were noted between peroxide values and oxidative stabilities and also between secondary oxidation products, measured by p‐anisidine value and stabilities at termination of the storage. Absorptivity at 232 nm and 270 nm increased gradually with the increase in time, due to the formation of conjugated dienes and polyenes. In general, oxidative stabilities of crude oils were stronger than their stripped counterparts and the order of oxidative stability was as follows: coriander > black cumin > niger seed. Levels of polar lipids in crude oils correlated with oxidative stability. Thus, the major factor that may contribute to the better oxidative stability of crude oils was the carry‐over of their polar lipids.
Synthesis of 2,2′‐Bipyridines: Versatile Building Blocks for Sexy Architectures and Functional Nanomaterials
Authors: Newkome George R. , Patri Anil K. , Holder Elisabeth , Schubert Ulrich S.
Published: January 2004

The latest synthetic strategies to prepare 2,2′‐bipyridine and its mono‐substituted, symmetrical and unsymmetrical 3,3′‐, 4,4′‐, 5,5′‐, and 6,6′‐disubstituted derivatives are critically discussed and evaluated. Different coupling procedures to achieve new symmetrical and unsymmetrical functionalized 2,2′‐bipyridines, such as Stille‐type, Negishi‐type, and Suzuki‐type cross‐coupling reactions are discussed in detail. Moreover, condensation procedures that allow further variations are presented. The application of functional group transformations for access to additional groups is examined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)