bluuebunny/crossref_metadata_2025 huggingface dataset:
Erdheim‐chester disease with extensive intraaxial brain stem lesions presenting as a progressive cerebellar syndrome
Authors: Evidente Virgilio Gerald H. , Adler Charles H. , Giannini Caterina , Conley Christopher R. , Parisi Joseph E. , Fletcher Geoffrey P.
Published: May 2005

We report a rare case of Erdheim‐Chester disease (ECD) presenting as a progressive cerebellar syndrome and diabetes insipidus. On magnetic resonance imaging, a 7‐mm extraaxial, enhancing mass was seen enveloping the right vertebral artery and was confirmed at autopsy to represent an adventitial xanthoma with lipid‐laden, foamy histiocytes. The cerebellar syndrome most likely resulted from extensive histiocytic infiltration of the pons, particularly the basis pontis and middle cerebellar peduncles.
Normal frontal perfusion in patients with frozen gait
Authors: Fabre Nelly , Brefel Christine , Sabatini Umberto , Celsis Pierre , Montastruc Jean Louis , Chollet François , Rascol Olivier
Published: May 2005

We have studied the frontal perfusion in the resting condition of two groups of patients with frozen gait: 10 patients with the syndrome of “isolated gait ignition failure” (IGIF) and 8 patients with idiopathic Parkinson's disease (PD) and severe “off” freezing. These patients were compared with two other groups: one including 20 age‐matched volunteers as normal control subjects and the other one including 12 patients with progressive supranuclear palsy (PSP) as a positive control with expected frontal hypoperfusion. Frontal perfusion was assed using single photon emission computed tomography (SPECT) regional cerebral blood flow measurement with intravenous 133Xenon. A significant frontal hypoperfusion was only present in the PSP group but not in the three othrs. These results do not support the hypothesis that start hesitations and freezing when walking are related to a frontal lobe dysfunction. However, it is possible that frontal neuronla dysfunction occurs without measurable cerebral blood flow changes in the resting condition.
Parkinsonism with HIV infection
Authors: Mirsattari Seyed M. , Power Christopher , Nath Avindra
Published: May 2005

We describe six patients with parkinsonism and another 10 patients with parkinsonian features with human immunodeficiency virus (HIV) infection. In 50% of these patients, the symptoms were precipitated by neuroleptics. In the remaining patients, no obvious cause other than HIV infection was identified. Discontinuation of the neuroleptics produced complete recovery in one patient and partial or no response in others. Rapid progression of parkinsonism was noted in two patients, one of whom was treated with high‐dose zidovudine (AZT) and benztropine. We conclude that patients with AIDS are at risk of developing an akinetic parkinsonism which may be precipitated by the use of neuroleptics, response to treatment is variable, and parkinsonism may be another primary HIV‐induced syndrome.
Early‐onset cerebellar ataxia (EOCA) with retained reflexes: Reduced cerebellar benzodiazepine‐receptor binding, progressive metabolic and cognitive impairment
Authors: Mielke RÜDiger , Hilker RÜDiger , Weber‐Luxenburger Gerald , Kessler Josef , Heiss Wolf‐Dieter
Published: May 2005

A family with two members who had early‐onset cerebellar ataxia (EOCA) with retained tendon reflexes had, in addition to their motor deficits, a progressive impairment of cognitive and visuospatial abilities. We used positron emission tomography (PET) with 11C‐flumazenil to study gammaaminobutyric type A/benzodiazepine receptor binding (BZR) and 18F‐2‐fluoro‐2‐deoxy‐D‐glucose to analyze longitudinally regional cerebral glucose metabolism. Flumazenil‐PET demonstrated loss of BZR binding that has not been shown in Friedreich's ataxia and olivopontocerebellar atrophy. These findings may be useful for differentiation of EOCA from other types of cerebellar ataxia. In comparison to age‐matched control subjects, these patients showed a global metabolic decline and predominant hypometabolism in the thalamus and cerebellum. The progressive metabolic derangement may be explainable by a disturbed integrity of cognition‐related networks resulting from secondary degeneration of cerebello‐thalamo‐cortical projections.
Adjuncts to dopamine replacement: A pragmatic approach to reducing the problem of dyskinesia in Parkinson's disease
Authors: Brotchie Jonathan M.
Published: May 2005

Dyskinesias following long‐term dopamine replacement therapy are a major limitation of current treatments for Parkinson's disease. Recently, attention has been focused on the concept of using non‐dopaminergic adjuncts to currently available therapies in an attempt to reduce the problem of dyskinesia. Thus, an enhanced understanding of the neural mechanisms underlying dyskinetic symptoms has led to the realization that it might be possible to manipulate non‐dopaminergic systems and reduce dyskinesia without compromising the antiparkinsonian efficacy of drugs such as L‐dopa. This article discusses how non‐dopaminergic manipulations could reverse the abnormalities in basal ganglia circuitry responsible for generating dyskinesia. It is proposed that potential anti‐dyskinetic drugs might include glutamate (NMDA) receptor antagonists, opioid receptor antagonists, cannabinoid receptor agonists or antagonists, α2 adrenergic receptor antagonists, and 5‐HT‐enhancing agents.
PTK787/ZK222584, a tyrosine kinase inhibitor of vascular endothelial growth factor receptor, reduces uptake of the contrast agent GdDOTA by murine orthotopic B16/BL6 melanoma tumours and inhibits their growth in vivo
Authors: Rudin Markus , McSheehy Paul M. J. , Allegrini Peter R. , Rausch Martin , Baumann Diana , Becquet Mike , Brecht Karin , Brueggen Josef , Ferretti Stephane , Schaeffer Fabienne , Schnell Christian , Wood Jeanette
Published: May 2005

Assessment of tumour vascularity may characterize malignancy as well as predict responsiveness to anti‐angiogenic therapy. Non‐invasive measurement of tumour perfusion and blood vessel permeability assessed as the transfer constant, Ktrans, can be provided by dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI). Using the orthotopic murine tumour model B16/BL6 melanoma, the small contrast agent GdDOTA (DOTAREM®; Guerbet, Paris) was applied to assess the vascular transfer constant, Ktrans, and interstitial leakage space, whereas intravascular iron oxide nanoparticles (Endorem®; Guerbet, Paris) were used to detect relative tumour blood volume (rTBV), and in one experiment blood flow index (BFI). No correlations were observed between these four parameters (r2 always <0.05). The B16/BL6 primary tumour and lymph‐node cervical (neck) metastases produced high levels of the permeability/growth factor, VEGF. To probe the model, the novel VEGF receptor (VEGF‐R) tyrosine kinase inhibitor, PTK787/ZK222584 (PTK/ZK) was tested for anti‐tumour efficacy and its effects on DCE‐MRI measured parameters of tumour vascularity. Data from the non‐invasive measure of tumour vascularity were compared with a histological measurement of vasculature using the DNA‐staining dye H33342. PTK/ZK inhibited growth of the primary and, particularly, cervical tumour metastases following chronic treatment for 2 weeks (50 or 100 mg/kg daily) of 1‐week‐old tumours, or with 1 week of treatment against more established (2‐week‐old) tumours. After chronic treatment with PTK/ZK, DCE‐MRI detected significant decreases in Ktrans and interstitial leakage space, but not rTBV of both primary tumours and cervical metastases. Histological data at this time‐point showed a significant decrease in blood vessel density of the cervical metastases but not the primary tumours. However, in the cervical metastases, the mean blood vessel width was increased by 38%, suggesting overall no marked change in blood volume. After acute (2–4 day) treatment, DCE‐MRI of the cervical metastases demonstrated a significant decrease in Ktrans and interstitial leakage space and also in the initial area under the enhancement curve for GdDOTA (IAUC), but no change in the rTBV or BFI. Thus, significant changes could be detected in the DCE‐MRI measurement of tumour uptake of a small contrast agent prior to changes in tumour size, which suggests that DCE‐MRI could be applied in the clinic as a rapid and sensitive biomarker for the effects of VEGF‐R inhibition on tumour blood vessel permeability and thus may provide an early marker for eventual tumour response. Copyright © 2005 John Wiley & Sons, Ltd.
Vulcanization characteristics and mechanical properties of nitrile rubber filled with short leather fibres
Authors: Natchimuthu N. , Radhakrishnan Ganga , Palanivel K. , Ramamurthy K. , Anand J. S.
Published: May 2005

Leather shavings have been used as filler in short fibre form for nitrile rubber reinforcement. Shavings neutralized with sodium bicarbonate and ammonia showed improved vulcanization characteristics and mechanical properties, whereas sodium hydroxide neutralized shavings exhibited poor properties. Swelling of the vulcanizates in water and 1% NaOH was found to increase with leather loading, whereas in MEK a reversed trend was observed. Thermogravimetric analysis indicates that the thermal stabilities of the vulcanizates fall between those of pure leather and gum nitrile rubber vulcanizate.
On the nature of intermolecular interactions in polymer blends. Use of model compounds as a tool for investigating polymer–polymer miscibility
Authors: Ruggeri Giacomo , Bertani Roberto , Aglietto Mauro , D'Alessio Aldo , Benedetti Enzo
Published: May 2005

An FTIR study has been performed on two low molecular weight model compounds of diethylmaleate functionalized polyethylene, ethyl 3‐carbethoxy‐4‐propylheptanoate (EPH) and ethyl 3‐carbethoxy‐4‐hexyldecanoate (EHD), recording spectra in different solvents (heptane, tetrahydrofuran, carbon tetrachloride, chloroform) and in the presence of a presumable PVC model, 2‐chlorobutane (2CB). These different systems allowed the observation of some correlations between spectroscopic data and chemical composition of solutions and functionalized polyethylene/PVC blends, supporting the hypothesis of specific hydrogen bond type interactions between the carboxylic oxygen of the functionalized polyethylene and the methinic hydrogens of PVC.
Thermodynamic state of reinforced interpenetrating polymer networks
Authors: Lipatov Yuri S. , Karabanova Ludmila V. , Sergeeva Ludmila M.
Published: May 2005

The free energies of mixing of two networks in the interpenetrating polymer network based on crosslinked polyurethane and poly(ester acrylate) have been determined by the vapour sorption method. It was established that the constituent networks in the IPN are not miscible.

The introduction of fillers of different chemical nature increases the compatibility. The thermodynamic affinity of the fillers to the individual networks and IPN was estimated. It was established that when the free energy of interaction of one or both components of the IPN with the filler is negative, reinforcement leads to the formation of a compatible and equilibrium system. For fillers having no affinity to the polymers, compatibilization is observed, which is connected with slowing down of phase separation in the system in the presence of filler.
Synthesis and properties of polydiacetylene‐containing polyesters
Authors: Lovell P. A. , Stanford J. L. , Wang Y‐F. , Young R. J.
Published: May 2005

A series of diacetylene‐containing polyesters with number‐average molar masses (GPC) in the range 900–4200 g mol−1 were prepared from terephthaloyl chloride and hexa‐2,4‐diyne‐1,6‐diol using benzoyl chloride as a monofunctional reactant for control of molar mass. Degrees of crystallinity were estimated from WAXD to be up to 29%. Correlations between molar mass, melting behaviour, degree of crystallinity and thermal cross‐polymerisation of diacetylene‐containing polyesters have been established using hot‐stage microscopy, DSC and resonance Raman spectroscopy. The polyester with M̄n of 1264 g mol−1 gave the best balance between processability and the ability to cross‐polymerise efficiently. Its degree of crystallinity before cross‐polymerisation was estimated from WAXD measurments to be 24%, a value coincident with the percentage conversion of diacetylene units to polydiacetylene chains measured by 13C solid‐state NMR. The optimum conditions for compression moulding the polyester to produce a material with a strong Raman spectrum involved heating under vacuum at 120°C for 6h after an initial 3 h heat‐up period. The material thus produced gave an intense Raman CC stretching band, which upon tensile deformation shifted linearly with strain to lower wavenumber by 12.0 cm−1 %−1. The potential use of the diacetylene‐containing polyesters in the preparation of model blends for use in quantitative micromechanics studies of stress transfer between phases is briefly discussed.
FTIR spectroscopic characterization of hydrogenated polyoctenamer and polynorbornene and DSC study of their thermal properties
Authors: Cataldo Franco
Published: May 2005

Diimide‐hydrogenated polyoctenamer and polynorbornene have been characterized by FT‐infrared spectroscopy and differential scanning calorimetry (DSC). Hydrogenated polyoctenamer has been studied in comparison with hydrogenated polybutadiene and polyethylene. A crystallinity ranging from 71% to 77% was found, while the melting point of hydrogenated polyoctenamer was found to be in the range 127–129°C. Hydrogenated polyoctenamer as well as hydrogenated polybutadiene resemble high density polyethylene (HDPE). Polynorbornene, which is completely amorphous, after hydrogenation shows a certain degree of crystallinity and a melting point of 140.8°C.
Synthesis and transacylating activity of isomeric Co(III)‐cyclodextrin artificial metalloenzymes
Authors: Akkaya Engin U. , Czarnik Anthony W.
Published: May 2005

Although the cyclen – Co(III) complex has exhibited amongst the greatest rate accelerations in acyl and phosphoryl transfer reactions, this catalytic unit has not been used previously in the design of an artificial metalloenzyme. For this study, β‐cyclodextrin derivatives of cyclen – Co(III) with attachments to the primary and secondary sides of the cyclodextrin torus were synthesized. The primary‐side cyclodextrin‐cyclen‐Co(III) conjugate accelerates the hydrolysis of p‐nitrophenylacetate by a factor of 1000 (pH 7.0, 25°C) in comparison with the water‐catalyzed reaction. Maximum reactivity occurs at pH 7, consistent with the known pKa values and hypothesised mechanism of action of Co(III) complexes. The secondary‐side cyclodextrin‐cyclen‐Co(III) conjugate is less reactive towards p‐nitrophenylacetate hydrolysis under saturating conditions. Reactivities towards an azide, a phosphonate and a phosphate triester were in each case less than five times greater than the buffer‐catalyzed rate.
Polymerization and copolymerization of β‐butyrolactone and benzyl‐β‐malolactonate by aluminoxane catalysts
Authors: Benvenuti Manuela , Lenz Robert W.
Published: May 2005

High molecular weight poly‐β‐hydroxybutyrate (PHB) and poly (β‐hydroxybutyrate‐co‐β‐benzyl malate) [P (HBBM)], were prepared by ring‐opening polymerization reactions of racemic β‐butyrolactone (BL) and racemic β‐benzyl malolactonate (BM) using two types of oligomeric aluminoxane catalysts prepared by the reaction of water with either triethyl‐aluminum (EAO) or triisobutylaluminum (IBAO). The stereoregularities, crystallinities, and molecular weights were determined for both the PHB homopolymers and the P (HBBM) copolymers by nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). All homopolymers and copolymers obtained could be separated into acetone‐soluble and acetone‐insoluble fractions. In every case the latter had higher degrees of crystallinity, higher molecular weights and higher degrees of stereoregularity (84–87% isotactic dyads) than the former. Hence all of the polymers obtained from both types of catalysts apparently had stereoblock isotactic structures. Copolymer compositions and monomer dyad sequence distributions were determined by NMR spectroscopy.
The synthesis of soluble, substituted silane high polymers by Wurtz coupling techniques
Authors: Miller R. D. , Thompson D. , Sooriyakumaran R. , Fickes G. N.
Published: May 2005

The Wurtz‐type coupling of a number of representative classes of substituted dichlorosilane monomers was investigated in considerable detail. Low temperature polymerization techniques, including ultrasonic activation, were also studied. Similarly, the effect of dipolar additives on the polymerization process was examined. The conclusions drawn from these studies provide some insight into the selection of useful polymerization conditions for the conversion of various monomer types into linear high polymers.
Dimethyl 1‐hexene‐2,5‐dicarboxylate, methyl methacrylate dimer, as polymerizable acrylic ester bearing bulky α‐substituent
Authors: Otsu Takayuki , Yamada Bunichiro , Fujita Mitsuo , Okuo Masami
Published: May 2005

Dimethyl 1‐hexene‐2,5‐dicarboxylate (MMAD), a methyl methacrylate dimer, which is an acrylic ester bearing a large α‐substituent, was polymerized and copolymerized. During the bulk polymerization at room temperature, an ESR spectrum assigned to the propagating radical was observed. MMAD which polymerized much slower than methyl methacrylate (MMA) was less reactive in copolymerization than MMA. These findings may exemplify that slow propagation concomitant with termination suppressed with steric hindrance could lead to polymer formation of MMAD. Thermogravimetric analysis of poly(MMAD) exhibited that the degadation through depropagation was facilitated by the α‐substituent. A relatively large chain transfer constant of MMAD in MMA polymerization, 9.8 × 10−3, was evaluated consistent with a considerable decrease in the molecular weight of poly (MMA) in the presence of a small amount of MMAD.
Photooxidation of blends of polystyrene and poly (vinyl methyl ether)
Authors: Chien Y. Y. , Pearce Eli M. , Kwei T. K.
Published: May 2005

Photooxidation of blends of polystyrene and poly (vinyl methyl ether) was studied at 30°C. The oxygen uptake by PS was negligible but PVME oxidized readily. The induction period of oxidation of PVME was prolonged by the presence of PS. The steady state rate of oxidation of the blend was strongly influenced by the segmental mobility of the blend which also governed the kinetics and morphology of phase separation. The molecular weight of PVME decreased more slowly in the blend as PS content increased. It was believed that the reaction between PVME radicals and PS resulted in less reactive PS radicals which retarded oxidation. The PS radicals eventually underwent chain scission reactions.
Essential work of fracture and j‐integral measurements for ductile polymers
Authors: Mai Yiu‐Wing , Powell Peter
Published: May 2005

In the ductile tearing of polymers that neck before failure it is shown that the specific essential fracture work (we), consisting of the energies dissipated in forming and tearing the neck, is a material property for a given sheet thickness and is independent of specimen geometry. Work of fracture experiments using both double deep‐edge notched (DENT) and deep‐center notched tension (DCNT) geometries with different ligament lengths yielded almost identical we values for a grade of high‐density polyethylene. These measurements for we are in fairly good agreement with the theoretical values based on the J integral evaluated along a contour surrounding the neck region near the crack tip. Under J‐controlled crack growth conditions, it is shown that Jc obtained by extrapolation of the JR curve to zero crack growth and the slope dJ/da are identical, respectively, to we and 4βwp obtained from the straight line relationship between the specific total work of fracture (wf) and ligament length (l).
Deformation mechanisms in biaxially drawn polyethylene
Authors: Gerrits Nicolé S. J. A. , Young Robert J.
Published: May 2005

The crystal orientation of solid‐state biaxially drawn solution‐crystallized ultra‐high‐molecular weight polyethylene (UHMW‐PE) film has been revealed from flat‐plate wide‐angle x‐ray scattering (WAXS) patterns and interpreted in terms of crystal plasticity. A slightly drawn film (λ ≤ 3 × 3) possesses only a (100) planar orientation, whereas in a highly drawn film (λ ≥ 6 × 6), a mixed (100) and {110} planar orientation is present. Crystal deformation is found to proceed both by slip on (100) and {110} planes, resulting in a (100) texture in a similar way to crystal deformation in uniaxially drawn polyethylene and by {110} 〈110〉 transverse slip and/or {310} twinning which results in a {110} texture. It is postulated that during transverse slip or twinning, the molecules deform without chain extension. As a consequence, neither the molecular draw ratio nor the tensile properties change significantly for macroscopic draw ratios above 10 in contrast to the data obtained for uniaxially drawn polyethylene.
Coupling scheme applied to solvent relaxation modified by dissolved polymer molecules
Authors: Ngai K. L.
Published: May 2005

A coupling scheme which has been successful in explaining relaxation properties of neat solvents can also predict their modifications by dissolved polymer molecules.
A Study of the Physical Significance of Three‐Dimensional signature waveforms
Authors: Kaye Brian H. , Leblanc John E. , Clark Garry G.
Published: May 2005

It has been shown that the projected area of a rotating fineparticle can be used to construct a signature waveform which is descriptive of some aspects of the three‐dimensional morphology of a fineparticle. If the fineparticle is rotated systematically about two mutually independent axes, through two sets of 90 degrees rotations, the signature waveform can be related to the surface area of the convex hull. It could be that the convex hull of a fineparticle is related to its fluid dynamic behaviour and its ability to modify the effective viscosity of a fluid in its suspension. This type of significance of different types of Cauchy signature waveforms are discussed. The concept of three‐dimensional signature waveforms is extended to cover the structural shape waveform and the fractal waveforms which, respectively, describe the spatial structure and the ruggedness of a fineparticle profile. The possible utilization of all three types of waveforms to describe in a complete manner the three‐dimensional structure of a rugged fineparticle is discussed.
Calibration of Optical Particle Counters with Respect to Particle Size
Authors: Fissan Heinz , Helsper Christoph , Kasper Wolfgang
Published: May 2005

In optical particle counters the calibration function describing the relationship between the amplitude of the scattered light pulses and particle size depends on several parameters. In this paper, several calibration methods are discussed. As an example, the calibration of an optical particle counter (HC‐15, Polytec GmbH & Co., Waldbronn, FRG) is demonstrated, using real aerosols with unknown particle shape and refractive index, and a precollector with known collection efficiency. The error analysis, when performed together with the results of an indirect check of the obtained calibration curve, provide evidence that this method yields good calibration curves for the aerosol being measured. The method is then applied to obtain the calibration curves for quartz dust, ash from a fluidized bed combustor and coal dust.
A Special Feeder for Diffraction Pattern Analysis of Dry Powders
Authors: Leschonski Kurt , Rüthele Stephan , Menzel Ulrich
Published: May 2005

Numerous unit operations in particle technology require that dry powders are fed into a system with as little fluctuation as possible in flow rate and velocity and that the powder is dispersed in flowing air. A feeding and dispersing system has been developed which allows mass throughputs between 0.1 and 20 kg/h. It has been used as a feeder unit for dry particle size analysis from diffraction patterns.
Measurement of Particle Size and Shape, some Reflections on the BCR reference material programme
Authors: Scarlett Brian
Published: May 2005

There are three basic philosophies which may be taken towards the problem of calibrating particle size measuring techniques. The first is to assume a model of the process and that the technique is thus absolute. The second is to calibrate an instrument using the particles which are to be measured themselves. In this paper, these three approaches are compared and contrasted. As an example, the programme of certification of the BCR samples is cited and discussed. The paper then advocates the use of the equivalent volume diameter as the basic particle size characterization and its combination with other measurements as shape determinations. The representation of both size and shape in this way is conveniently presented in the form of orthogonal diagrams.
Measurement of Particle Size Distributions in Gas Flows with an Optical particle counter
Authors: Büttner Helmut
Published: May 2005

In order to characterize flow separation and classification processes, particle size distributions must be measured in the airborne state without affecting the state of dispersion or disturbing the flow. Light scattering devices with an optically defined measuring volume are specially designed for this purpose. However the light scattering device must be calibrated using non‐ideal particles which are present within the multiphase flow, preferably on an equivalent diameter based on settling rate. Such a calibration can be achieved by measuring with an optical particle counter before and after an impactor in droplet systems and a sampling cyclone in systems of solid particles. By measuring the calibration curves the size distribution of the investigated particles are also determined. This measuring technique allows the best use of the optical particle counter in industrially relevant cases which may have high particle concentrations, wide distributions, non‐ideal particles and an undefined state of dispersion.
In‐Process Particle Size Distribution Measurements and Control
Authors: Harvill Thomas L. , Hoog Jared H. , Holve Donald J.
Published: May 2005

In‐process measurement of particle size and concentration distributions provides continuous analysis, quality control, and optimization of product yield. As process production rates continue to improve, the delay between laboratory analysis and process correction of the product stream becomes more significant and costly in many commercial applications. Elimination of sample handling and operator manipulation is now possible for most pneumatic flows using optical methods which are properly interfaced with the process stream. Insitec has developed such an instrument based on ensemble laser‐diffraction that has been successfully applied to a wide range of research and industrial process applications.

As part of the adaptation of instrumentation to the specific needs of different process applications, we have developed several different interface arrangements, including a direct inline system and an eductor bypass instrument. A specific window purge design has been developed and shown to operate for extended time periods (exceeding one month and more) without maintenance. To address the wide range of operating concentrations that occur in practice, a variable pathlength interface has been developed along with a deconvolution algorithm that corrects multiple scattering effects for light transmissions down to 20%. Distribution update rates are computed and displayed in less than 5 seconds. This methodology is described along with measurements in a non‐steady pharmaceutical powder processing application. Results show uniform size measurement for ten‐fold concentration variations. Real time measurements allowed diagnosis and correction of non‐steady feed rates to a classifier‐mill.
Morphological Characterization of Flowing Particles by Image Analysis Techniques
Authors: Bonifazi Giuseppe , Francini Franco , Guarnieri Vanni , Longobardi Giuseppe , Massacci Paolo , Recinella Marco
Published: May 2005

The guidelines which are at the base of the definition of a system capable of operating on a slurry containing the solid particulate for its characterization are described. All the considerations have been developed with particular reference to the case of a granular heterogeneous material in particular, the different research problems, making a comparison with the case of static images, acquired under laboratory conditions, are pointed out. Attention was focused on problems of acquisition and digital image processing to obtain information which is clean from noise and errors. The considerations and procedures analysed show general validity and can be applied to a large number of problems linked to the “on‐line” morphological characterization of particulate solids materials. Some results for morphological characteristics of lead sulphide (PbS) samples are reported.
Influence of the Measurement Volume on the Phase Error in Phase Doppler Anemometry. Part 2: Analysis by extension of geometrical optics to the laser beam; Refractive mode operation
Authors: Albrecht Heinz‐E. , Wenzel Marcus , Borys Michael
Published: May 2005

The influence of the measurement volume can be investigated by using extended geometrical optics, which is based on geometrical optics by including the amplitude and phase distribution in the laser beam. The dynamics in phase Doppler anemometry can be analysed, in addition to effects of the particle size‐dependent detection volume. Extended geometrical optics has been developed as a powerful tool to investigate these influences for each order of light scattering separately. Phase errors caused by Gaussian‐beam intensity distribution and the curvature of the wave fronts beyond the beam waist can easily be calculated. According to Part 1 (Reflective Mode Operation), the influence of the particle trajectories on measured phase and mass concentration is simulated for refractive mode operation.
Characterisation of Particle Size for Polydisperse Powders aerosolised and detected by light scattering
Authors: Sato Shintaro , Pui David Y. H. , Vincent James H.
Published: May 2005

This paper describes a study to determine the most appropriate particle size parameter for polydisperse powders dispersed as aerosol and detected by light scattering. It is relevant to many areas of engineering research. By means of calculations of the intensity of light scattered from particles of different sizes, it has been shown that the surface median aerodynamic diameter (SMAD) is an appropriate measure for polydisperse aerosolised powders. The microscope‐based procedure for obtaining the SMAD is described, as well as its implementation for narrowly‐graded polydisperse powders of fused alumina of type which have been widely used in studies of particle transport in wind tunnels. It was shown that for the fused alumina powders examined, SMAD = 1.25 x (PASMAD), where PASMAD is the projected area surface median aerodynamic diameter.
Coal Handleability — A good or a bad coal?
Authors: Brown Gareth J. , Creasey Des S. , Miles Nick J.
Published: May 2005

The avalanching behaviour of two coal types was determined, one of good and the other of poor handleability characteristics. This revealed significant differences in the nature of flow of the coals. Analysis of the strange attractors of the weight series of avalanches enabled quanitification of this difference, and the establishment of practical, relative criteria for the measurement of coal handleability. These criteria will now enable a structured study of the variables that affect handleability, for example proportion of fines and moisture content, and industrial consumers of coal to specify minimum acceptable limits for its transport characteristics.
Stilbene and Azobenzene Diazonium Compounds as dye reagents for crown ethers
Authors: Walkow Fred , Israel Gunther
Published: May 2005

The change of light absorption of six coloured diazonium compounds (1, 2a, 2b, 3, 4, 5) on complexation with five 18‐crown‐6 derivatives (6–10) in 1,2‐dichloroethane was investigated. In the benzene, stilbene and azobenzene series complexation produces only hypsochromic shifts of the intramolecular ct‐band of the diazonium ions up to 140 nm. The extend of the shift is effected by ion pairing. The ct‐transition energy of the complexes diazonium ion is independent on the present anion in contrast to the uncomplexed compounds. The colour changes are not caused by host to guest charge transfer or E/Z‐isomerisation of the stilbene and azobenzene derivatives. A quantitative explanation of the colour changes is given basing on an electrostatic interaction model.
5‐Aminothiazole aus Dithioestern und α‐Aminoacetonitril
Authors: Thiel W.
Published: May 2005

5‐Aminothiazoles from Dithiocarboxylic Esters and α‐Aminoacetonitrile

Carbamoyldithiocarboxylicesters 1 and heteroaryldithiocarboxylic esters 2 react with α‐aminoacetonitriles under mild conditions to form 2‐carbamoyl‐5‐aminothiazoles 5 or 2‐heteroaryl‐5‐aminothiazoles 6. The intermediate N‐cyanomethylthiooxamides 3 can be isolated. The 2‐heteroaryl‐5‐aminothiazoles 6 and their acyl derivatives 7 are highly fluorescent, in contrast to the azomethines 8 derived from 6.
Aromaticity as a Quantitative Concept. 4. Less familiar five‐ and six‐membered monocyclic heterocycles
Authors: Katritzky Alan R. , Barczynski Piotr
Published: May 2005

An additional set of 23 monoheterocycles was subjected to AM1 calculations, and the characteristics thus determined, together with available experimental data, treated by PC analysis. Utilizing characteristic loadings previously determined for other monoheterocycles, scores for the 23 monoheterocycles were deduced. The new scores correlate well with those previously found, and with the chemical nature of the heterocycles. The dominant influence on the t1 is the nature of the hetero atoms present, whereas the dominant influence on t2 is the number of hetero atoms present. It is concluded that pyridine‐like nitrogen atoms have relatively little effect on clasical aromaticity: five‐membered rings are less aromatic than six‐membered, the presence of an oxygen atom has a particularly aromaticity‐reducing effect, whereas the effect of sulfur is much less than oxygen and only a little more than nitrogen. The predictive power for the present compounds is limited by the relative paucity of and some problems with the input data but suceeds well for Ix′, ΔN and ΔHf.
Crystalline Sodium Selenocarboxylates – synthesis and characterization
Authors: Kato Shinzi , Kageyama Hideki , Takagi Kazutaka , Mizoguchi Kazuaki , Murai Toshiaki
Published: May 2005

A series of sodium selenocarboxylates 2 were isolated from the reaction of diacyl selenides with sodium ethanolate and characterized. A convenient preparation of the sodium salts 2 by the direct reaction of acyl chlorides with sodium selenide was also established. The salts are colourless to slightly pale yellow crystals and labile towards moisture. They readily react with alkyl iodides at room temperature to give the corresponding Se‐alkyl esters 3.
Donorsubstituierte 2,4‐Diazacyclopentadienone und indigoide 1,3,5,7‐Tetraazafulvalene
Authors: Glas G. , Gompper Rudolf , Junius M. , Mertz R. , Wagner H.‐U. , Nöth Heinrich , Staudigl M.
Published: May 2005

Donor Substituted 2,4‐Diazacyclopentadienones and Indigoid 1,3,5,7‐Tetraazafulvalenes

Hydrolysis of tris(diethylamino)imidazolylium chloride gives rise to 2,5‐bis‐diethyl‐amino‐4H‐imidazolin‐4‐one; thiolysis leads, depending on conditions, to 2,5‐bis‐diethylamino‐4H‐imidazolin‐4‐thione or potassium 2,6‐bis‐diethylamino‐1,3,5,7‐tetraazafulvalene‐4,8‐dithiolate. The latter can be protonated to form green 2,6‐bis(dimethylamino)‐3,4,7,8‐tetrahydro‐1,3,5,7‐tetraaza‐fulvalen‐4,8‐dithione, a new indigoid compound, and alkylated to give blue 2,6‐bis‐diethylamino‐4,8‐bis‐alkylthio‐1,3,5,7‐tetraazafulvalenes. Treatment of 2,5‐bis‐diethylamino‐4H‐imidazolin‐4‐thione with copper furnishes 2,6,4,8‐tetrakis‐diethylamino‐1,3,5,7‐tetraazafulvalene. – Oxidation of 2,6‐bis‐dimethylamino‐3,4,7,8‐tetrahydro‐1,3,5,7‐tetraazafulvalen‐4,8‐dithione gives rise to (2,2′‐bis‐diethylamino‐4,4′‐bi(4H‐imidazol)‐5,5′‐dithione, corresponding to dehydroindigo, and reduction leads to a colorless compound, corresponding to leucoindigo.
α‐substituierte Phosphonate. 56. Synthese und Reaktionen von 1‐Formylamino‐2,2,2‐trichlorethanphosphonaten
Authors: Scheidecker S. , Köckritz A. , Schnell M.
Published: May 2005

α‐substituted Phosphonates. 56. Synthesis and Reactions of 1‐Formylamino‐2,2,2‐trichloroethanephosphonates

The chemical behaviour of formylamino phosphonates 2, prepared from 1,2,2,2‐tetrachloroethylformamid and trialkylphosphites, was investigated. The phosphonate 2b was cleaved under acidic conditions to aminosubstituted phosphonate 3. The phosphonates 2 and 3 react with bases to 2,2‐dichlorovinylphosphonates 8 and 6, respectively. Oxazoles 9 are formed by treatment of the phosphonate 2 and 8, respectively, with prim. or sec. amines.
Tetrazolverbindungen. 5. Synthese und Umaminierung von Enaminoketonen der Tetrazolreihe
Authors: Fischer G. W.
Published: May 2005

Tetrazole Compounds. 5. Synthesis and Transamination of Enamino Ketones of the Tetrazole Series

Tetrazole‐5‐acetaldehyde enamines 5 react with aliphatic and aromatic carboxylic acid chlorides in the presence of an auxiliary base (e.g. pyridine or triethylamine) to give tetrazolylsubstituted enamino ketones 6. The latter can be modified by acid‐catalyzed transamination with secondary aliphatic amines (e.g. diethylamine, pyrrolidine, piperidine, morpholine, hexamethylene imine) yielding 5‐(1‐acyl‐2‐dialkylamino‐vinyl)‐1‐aryl‐1 H‐tetrazoles 7. The analogue transamination of 6 with primary alkyl, aralkyl, and aryl amines results in corresponding secondary enamino ketones 8, which exist in solution as an equilibrium mixture of the Z and E form. Acylation of secondary tetrazole‐5‐acetaldehyde enamines 9 does not lead to 8, but to the isomeric N‐acyl derivatives 10. – Characteristic 1H‐n.m.r., u.v., and i.r. spectroscopic data of the novel products are reported.
4‐Anilino‐5,7‐dinitrobenzofurazan – Untersuchungen zur Struktur und Reaktivität
Authors: Niclas H.‐J. , Göhrmann B. , Ramm M. , Schulz B.
Published: May 2005

4‐Anilino‐5,7‐dinitrobenzofurazan – Studies on Structure and Reactivity

4‐Anilino‐5,7‐dinitrobenzofurazan3reacts with gaseous ammonia at room temperature under elimination of aniline leading to4. Compound3may also be transformed into the isolable salt6by treatment with aqueous KHCO3, whereas4reacts with KHCO3furnishing potassium 5, 7‐dinitrobenzofurazan‐4‐olat5. As shown by X‐ray analysis and CNDO/2 calculations of3, the case with which the nucleophilic substitutions proceed may be explained by the assumption of an azomethine structure in4and6.
Photoinitiierte Polymerisation mit Dialkoxythiocarbonyldisulfiden – eine Polymerisationsreaktion mit Primärradikalabbruch
Authors: Timpe Hans‐Joachim , Ali Salah , Ulrich Sven , Müller Gerd , Kronfeld Klaus‐Peter , Zubarev V. E.
Published: May 2005

Photoinitiated Polymerization with Dialkoxy Thiocarbonyl Disulfides – a Polymerization Reaction with Primary Radical Termination

The photoinduced free radical polymerization of methyl methacrylate (MMA) and some other vinyl monomers using dialkoxy thiocarbonyl disulfides (1–4) as photoinitiators was studied. The photolysis of these initiators leads to cleavage of the SS bond, which was determined by spin trapping experiments with phenyl tert‐butyl nitrone. No evidence was found for a further thermal decomposition of the primary alkoxy thiocarbonyl sulfide radicals (R·) at room temperature. In the absence of scavengers the primary radicals react back exclusively to the initial compounds, due to a strong cage effect. By means of UV spectroscopic measurements and in the presence of MMA the quantum yields of the initiator decomposition were detected to be 0.8. The polymerization of acrylic and methacrylic derivatives can be initiated by the R·, contrary to the situation with fumarates and maleates. The mechanism of MMA polymerization depends on the light intensity absorbed by the initiators. At high intensities the combination of primary and polymer radicals terminates the chain reaction. This follows from the measured monomer exponent of α = 2, the light intensity exponent of β = 0,2 and the number of thiocarbonyl end groups of 2 in the polymers isolated. Contrary to this, in the low intensity region the experimental data obey the ideal kinetic equation. Kinetic modelling gives evidence for an interaction of the monomer with the cage radicals.
Vergleichende Untersuchungen zur Arylaminierung von Benzofuroxan‐Derivaten
Authors: Göhrmann B. , Niclas H.‐J.
Published: May 2005

Comparative Studies on Arylamination of Benzofuroxan Derivatives

The amination of benzofuroxan 2a and monosubstituted benzofuroxans 2b–e with alkali metal salts of formanilides 1 and sodium acetanilides 6 is described. Thus, the reaction of 2a with 6a–d gives the benzotriazole 1‐oxides 3a–d. The benzofuroxans 2b and 2c react with sodium formanilides to give the isomeric mixtures 3f/3g and 3h/3i. Potassium 4‐nitroformanilide reduces 2a furnishing benzofurazan 7. Nitrobubstituted benzofuroxans such as 2d and 2e undergo a carbocyclic amination leading to the benzofurazans 8 and 9.
Hydrierung von Crotonaldehyd und Acetaldol mit modifizierten Pd‐Trägerkatalysatoren. II. Zum Einfluß einer Chromiummodifizierung auf Pd Al2O3‐Katalysatoren
Authors: Bohm D. , Kripylo P. , Stobbe J.
Published: May 2005

Hydrogenation of Crotonaldehyde and Acetaldol with Modified Pd‐Supported Catalysts. II. On the Influence of a Chromium Modification of Pd/Al2O3 Catalysts

The catalytic properties in hydrogenation reactions on chromium containing Pd/Al2O3 catalysts are influenced by an “esemble effect.” The specific activity in the hydrogenation of crotonaldehyde to n‐butyraldehyde is independent of the chromium content in the Pd/Al2O3 catalysts. But the specific activity for the hydrogenolysis of ethane is decresed with the chromium content of the catalysts. On the other hand, was observed that the specific activity of the conversion of acetaldol to n‐butyraldehyde rises with increasing chromium content. This specific activity is higher than the specific hydrogenation activity.

This fact can be considered as an argument for an asynchron hydrogenolysis of the hydroxyl group in the formation of n‐butyraldehyde from acetaldol on PdCr/Al2O3 catalysts.
Protein fluorescence quenching by small molecules: Protein penetration versus solvent exposure
Authors: Calhoun Dorothy B. , Vanderkooi Jane M. , Holtom Gary R. , Englander S. Walter
Published: May 2005

Experiments were done to test the thesis that acrylamide and similar small molecules can penetrate into proteins on a nanosecond time scale. The approach taken was to measure the pattern of fluorescence quenching exhibited by quenching molecules differing in molecular character (size, polarity, charge) when these are directed against protein tryptophans that cover the whole range of tryptophan accesibility. If quenching involves protein penetration and internal quencher migration, one expects that larger quenchers and more polar quenchers should display lesser quenching. In fact, no significant dependence on quencher character was found. For proteins that display measurable quenching, the disparate quenchers studied display very similar quenching rate constants when directed against any particular protein tryptophan. For several proteins having tryptophans known to be buried, no quenching occurs. These results are not consistent with the view that the kinds of small molecules studied can quite generally penetrate into and diffuse about within proteins at near‐diffusion‐limited rates. Rather the results suggest that when quenching is observed, the pathway involves encounters with tryptophans that are partially exposed at the protein surface. Available crystallographic results support this conclusion.
Translational repression in vitro by the bacteriophage T4 regA protein
Authors: Adari Hedy Y. , Spicer Eleanor K.
Published: May 2005

The bacteriophage T4 translational represor regA protein has been purified from an overproducing strain, and its activity has been studied in simple in vitro protein synthesis reactions. RegA protein was found to inhibit the translation of T4 genes 44, 45, and ORF45‐1 in a concentration‐dependent fashion. Expression of two other T4 genes which are insensitive to regA protein in vivo, genes 32 and 43, was unaffected by the presence of regA protein. Specific inhibition of synthesis of genes 44, 45, and ORF 45‐1 proteins was achieved with 5–20 μM concentrations of regA protein, without the addition of any other T4 encoded proteins or cofactors. When in vitro protein synthesis was performed in two steps, uncoupling translation from transcription, regA protein had an inhibitory effect regardless of whether it was added at the initiation of transcription or only at the translation step. This indicates that regA protein functions during the translation step of protein synthesis in vitro in agreement with previous in vivo studies of regA protein.
Cloning, expression, and nucleotide sequence of livR, the repressor for high‐affinity branched‐chain amino acid transport in Escherichia coli
Authors: Antonucci Tammy K. , Wagner Lois M. , Oxender Dale L.
Published: May 2005

The livR gene encoding the repressor for high‐affinity branched‐chain amino acid transport in Escherichia coli has been cloned from a library prepared from the episome F106. The inserted DNA fragment from the initial cloned plasmid, pANT1, complemented two independent, spontaneously derived, regulatory mutations. Subcloning as well as the creation of deletions with Bal31 exonuclease revealed that the entire regulatory region is contained within a 1.1‐kb RsaI‐SalI fragment. Expression of the pANT plasmids in E. coli minicells showed that the regulatory region encodes one detectable protein with an apparent molecular weight of 21,000. DNA sequencing revealed one open reading frame of 501 bp encoding a protein with a calculated MW of 19,155. The potential secondary structure of the regulatory protein has been predicted and it suggests that the carboxy terminus may fold into three consecutive alpha helices. These results suggests that the livR gene encodes a repressor which plays a role in the regulation of expression of the livJ and the livK transport genes.
Activation of retinal rod cyclic GMP‐phosphodiesterase by transducin: Characterization of the complex formed by phosphodiesterase inhibitor and transducin α‐subunit
Authors: Deterre Philippe , Bigay Joëlle , Robert Mylène , Pfister Claude , Kühn Herman , Chabre Marc
Published: May 2005

The GTP‐binding subunit of transducin (Tα) activates the cGMP phosphodiesterase (PDE) of bovine retinal rods by relieving the constraint imposed by the inhibitory subunit PDEγ. We have isolated and characterized the complex Tα.GTPγS‐PDEγ formed when Tα is activated by the nonhydrolyzable analog GTPγS. Sedimentation and light‐scattering techniques demonstrate that, in contrast to free Tγ.GTPγS, which is soluble, the Tα.GTPγS‐PDEγ complex, as well as Tα.GTP‐PDEγ, is membrane bound at cytosolic ionic strength. It is eluted from the membrane at low ionic strength as a monomeric and 1:1 stoichiometric complex. The relative affinities of PDEγ for PDEαβ and for Tα.GTP are discussed.