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The use of heavier feedstocks, or even the possibility of direct conversion of crude oil into chemicals has created new challenges for the steam cracking process, as severe fouling in the different sections of steam crackers is observed then. In order to obtain a more fundamental understanding about the fouling phenomenon and its relation to feedstock composition and process conditions the "Fouling Assessment SeTup (FAST)" was developed. This experimental unit was used to determine the fouling tendency of a heavy hydrocarbon mixture (HHM) in the different sections of a steam cracker, i.e. convection, radiant, and transfer line heat exchanger (TLE) sections via a post cracking decoking procedure and the continuous weighting of a suspended coupon in TLE with a Magnetic Suspension Balance (MSB). Additionally, a fouling mitigation concept of wetting fluid injection in TLE via an in-house apparatus was tested. The injection of a paraffinic fluid substantially reduced fouling in this section. [ABSTRACT FROM AUTHOR]

The hydrolysis of copper(II) chloride is the water splitting process in the copper-chlorine thermochemical hydrogen production cycle. In this paper, a simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC/TG) technique is used to determine the transitional temperature and kinetics of the thermal decomposition of CuCl. Thermodynamic analysis is performed on the decomposition reaction for a comparison with the thermogravimetric analysis results. The CuCl decomposition temperature obtained from thermogravimetric experiments is found to be higher than that predicted from the thermodynamic analysis. This broadens the available operating temperature range of the CuCl hydrolysis step for the Cu-Cl cycle. It is also found that the decomposition product CuCl may completely evaporate if the temperature is higher than its melting point, so the CuCl hydrolysis reaction should be operated below the melting point of CuCl (430 °C) to avoid the undesirable CuCl and Cl byproducts. A preliminary correlation is proposed in this paper for the decomposition kinetics in terms of the extent of converting CuCl to CuCl and Cl. [ABSTRACT FROM AUTHOR]

Specificity of CH dry reforming mechanism for Me-supported doped ceria-zirconia catalysts with high oxygen mobility was elucidated using a combination of transient kinetic methods (TAP, SSITKA) with pulse microcalorimetry and in situ FTIRS. Steady-state reaction of CH dry reforming is described by a simple redox scheme with independent stages of CH and CO activation. This is provided by easy CO dissociation on reduced sites of oxide supports followed by a fast oxygen transfer along the surface/domain boundaries to metal sites where CH molecules are transformed to CO and H. The rate-limiting stage is irreversible transformation of CH on metal sites, while CO transformation proceeds much faster being reversible for steady-state surface. The oxygen forms responsible for CH selective transformation into syngas correspond to strongly bound bridging oxygen species with heats of desorption ≈600-650 kJ/mol O, most probably bound with pairs of Pr and/or Ce cations able to change their oxidation state. Ni + Ru clusters could be involved in CO activation via facilitating C-O bond breaking in the transition state, thus increasing the rate constant of the surface reoxidation by CO. Strongly bound carbonates are spectators. [ABSTRACT FROM AUTHOR]

The goal of the Grid Application Development Software (GrADS) Project is to provide programming tools and an execution environment to ease program development for the Grid. This paper presents recent extensions to the GrADS software framework: a new approach to scheduling workflow computations, applied to a 3-D image reconstruction application; a simple stop/migrate/restart approach to rescheduling Grid applications, applied to a QR factorization benchmark; and a process-swapping approach to rescheduling, applied to an N-body simulation. Experiments validating these methods were carried out on both the GrADS MacroGrid (a small but functional Grid) and the MicroGrid (a controlled emulation of the Grid). [ABSTRACT FROM AUTHOR]

In order to study the effect of the α,β crystalline structure of polypropylene (PP) on its mechanical properties, it is necessary to prepare samples with variable α/β-phase content but with constant crystallinity and constant spherulite size. With this objective, heat treatment was first defined to be applied to an isotactic PP containing a β nucleating agent in order to achieve these conditions. Then study of the effect of the β-phase content on the tensile properties and fracture behaviour has been done at room temperature. The mechanical properties at fracture were assessed by three-point bending tests and were analysed on the basis of the “Essential Work of Fracture” (EWF). The results show that the elongation at fracture under tensile stress and the “near” Plane-Strain Essential Work of Fracture, wIe, increase substantially with the β-phase content. Besides, Young's modulus and the yield stress in tensile tests decrease slowly with the β-phase content. Finally, these results are analysed taking account the differences in structure of the α and β spherulites. [ABSTRACT FROM AUTHOR]

A new method to grow single crystals with stoichiometry close to 1:1:2 of CuInTe2, an important member of the Cu-III-VI2 family of semiconductors is described. This consists of tellurization in the liquid phase of stoichiometric Cu and In and later solidification under directional freezing. It is found from energy dispersive spectroscopy that the ingots obtained with the evaporation temperature (Tt) of Te at 590 and 635°C were very close to the ideal stoichiometry 1:1:2. Samples of all ingots obtained with Tt between 530 and 690°C, as studied by x-ray and differential thermal analysis, were of single phase having chalcopyrite structure and p-type conductivity. Optical and electrical characterization of different ingots were made. The acceptor ionization energy EA and the density of states effective mass m of the holes are estimated from the temperature dependence of the hole concentration p in samples of different ingots. m = (0.78 ± 0.02) me agrees quite well with the reported value. From a combined analysis of the variation of EA with p1/3 and the knowledge of molecularity and valence stoichiometry of each sample, it is established that the shallow acceptor level observed in different samples with EA (0) ⋍ 30 meV is due to VIn. [ABSTRACT FROM AUTHOR]

Centrifugal projections to several sensory systems modulate the afferent activity during active behaviors. To see whether such modulation occurred in the visual system, we recorded the activity of isthmo-optic neurons in awake chickens during eye movements. We find that the discharge of all isthmo-optic neurons tends to stop during saccades, although every neuron does not pause for every saccade. The pause begins at approximately the same time as the saccade, and pause duration is correlated with saccade duration. Pausing during saccades occurs in both dark and light suggesting that it is motoric rather that visual in origin. In addition, we find that the spontaneous activity of isthmo-optic neurons increases in darkness. We discuss the significance of the saccadic modulation of isthmo-optic activity in terms of possible functions of the centrifugal projection in modulation of ganglion cell activity. [ABSTRACT FROM AUTHOR]

To evaluate CD34+ selection of peripheral blood stem cells (PBSC) as a graft for autologous transplantation. Eight relapsing follicular lymphoma (FL) patients were submitted to CD34+ autologous stem cell transplantation (ASCT). All patients received at least two front line conventional therapies; mean time to treatment failure (TTF) was 4.5 months. Patients had disseminated stage III-IV disease after a median number of 2.1 relapses. Chemotherapy and G-CSF were used as mobilization for leukapheresis. CEPRATE SC concentrator (CellPro, Inc, Bothell, WA) was used to select CD34+ cells from leukapheresis products. With a mean of 1.8 leukaphereses per patient, 8.1 × 108 mononuclear cells (MNCs)/kg were collected. After the selection process, the median number of MNCs was 9.4 × 106/kg; 4.3 × 106/kg CD34+ cells and 17 × 104/kg CFU-GM, with a purity of 83.7% and a viability of 89.2%. Mbr bcl2/IgH PCR analysis of 5 grafts showed that initial buffy-coat, and CD34- fractions were negative in 3 cases and positive in 2 cases (from whom selected CD34+ fraction remained positive in 1 case). After a conditioning regimen including total body irradiation, cyclophosphamide and etoposide, CD34+ selected cells were reinfused. All patients but one had successful engraftment, median time to WBC > 1 × 109/l was 12 days and platelets > 50 × 109/l 17 days. No severe infectious complications were seen. After transplant, with a minimum follow up of 2 years, 5 patients are still in complete remission (CR). Three patients have relapsed after 1 year of transplant with a mean TTF of 15.6 months. We conclude that PBSC CD34+ selection for ASCT was a safe technique, capable of reconstituting hemopoiesis without severe complications for high risk FL patients included in this study. The effects of tumor cell purging need to be evaluated in a larger series. [ABSTRACT FROM AUTHOR]

The dielectric properties of the system water/AOT/dodecane are studied as a function of volume fraction φ of the dispersed phase and molar ratio n (water/surfactant). Data shows that the spherical model is valid only at low n values or low φ values. At high concentrations of dispersed phase, one has to consider micellar aggregation or deformation. [ABSTRACT FROM AUTHOR]

Copyright of Virchows Archiv A Pathological Anatomy & Histology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Variations in the embryo proteins separated by SDS-PAGE have been observed in 43 cultivated varieties of Oryza sativa L. Cluster and discriminant analysis applied to both protein components and morphological characters indicate that knowledge of the differences in embryo proteins can improve our understanding of genetic affinity and make it easier to differentiate between varieties of similar genetic backgrounds. [ABSTRACT FROM AUTHOR]

Triparental crosses were carried out between Chinese hamster and mouse cell lines, by using combinations of recessive and dominant markers. Evidence is provided that triparental somatic hybrids arose at relatively high frequencies in triselective media, after fusing with polyethylene glycol mixtures of three cell types carrying the appropriate resistance markers. The karyotypes of these hybrids were consistent with their triparental origin. Since triparental chromosome complements were observed also in some of the cells selected for two markers only, the possibility is discussed that nuclear multiplicities higher than two in fused cells may favor, rather than hinder, viable hybrid formation. [ABSTRACT FROM AUTHOR]

A number of parameters were measured in a series of 12 hybrid cell clones from Chinese hamster and mouse cells to test the hypothesis that asymmetrical chromosome loss may result from asynchrony in the replication of the two parental sets of chromosomes. All clones tended to lose telocentric (mouse) chromosomes with culture time, irrespective of the starting ratio of parental chromosomes, and in all clones, biarmed (hamster) chromosomes appeared to complete DNA replication slightly earlier than telocentrics. However, no quantitative correlation could be established between the degree of asynchrony in chromosome DNA replication and the extent of chromosome loss. It appeared that telocentric chromosomes were lost more readily from those clones which started with a high hamster-to-mouse chromosome ratio. [ABSTRACT FROM AUTHOR]

An expression of the relaxation function of linear polydisperse polymers is proposed in terms of intermolecular couplings of reptative chains. The relaxation times of each molecular weight are assumed to be shifted according to a tube renewal mechanism accounting for the diffusion of the surrounding chains. The subsequent shift is applied to the relaxation function of each molecular weight obtained from an analytical expression of the complex compliance J(ω). Therefore the complex shear modulus G(ω) is derived from the overall relaxation function using the probability density accounting for the molecular weight distribution and four species-dependent parameters: a front factor A for zero-shear viscosity, plateau modulus G, activation energy E and characteristic temperature T. All the main features of the theology of polydisperse polymers are described by the proposed model. [ABSTRACT FROM AUTHOR]

The elongational properties of a series of six polypropylene and two polystyrene samples have been studied at constant rate of strain. A Wagner-type constitutive equation has been used to fit the experimental data, and the shape of the damping function has been correlated with the polydispersity index of the samples. As the memory function or relaxation function of linear viscoelasticity may be derived from the molecular-weight distribution using either molecular or phenomenological models, it is therefore possible to calculate the stress growth function of a linear polymer in elongation from its molecular-weight distribution. [ABSTRACT FROM AUTHOR]

The uniaxial elongational properties of various polyethylenes have been evaluated using an elongational rheometer and a melt-strength apparatus. It is possible to derive the data obtained in elongation from the distribution of relaxation times obtained from oscillatory shearing measurements (linear viscoelasticity), using a Wagner constitutive equation. The effects of the molecular parameters of the samples have been studied, in particular the effect of polydispersity on the shape of the damping function. [ABSTRACT FROM AUTHOR]

The complex shear modulus G ( ω) of polymer melts is directly related to the molecular structure of these large entangled chains. We describe here a new method called TDMS (Time Domain Mechanical Spectroscopy) that gives the complex shear modulus G ( ω), from measurements in the time domain (stress growth before Newtonian flow, stress relaxation after cessation of flow), performing a Carson-Laplace Transform of either one of these transient functions. We get then G ( ω) in the terminal region of relaxation (low frequencies) with reasonable accuracy in a much shorter time than needed by a sweep in the frequency domain. [ABSTRACT FROM AUTHOR]

Copyright of Rheologica Acta is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rheologica Acta is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rheologica Acta is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rheologica Acta is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Two cases of giant cerebral aneurysms, the diagnosis of which was made by angiography after a dubious CT scan, are reported. [ABSTRACT FROM AUTHOR]

A retrospective appraisal of traditional neuroradiological techniques (such as direct röntgenograms, cerebral angiography RISA-cisternography, and pneumo-cisterno-encephalography, as opposed to the 'new' technique of computer-assisted tomography) was carried out in a series of 82 cases of opto-chiasmatic arachnoiditis, all surgically verified. It is concluded that none of these examinations can provide a reliable diagnosis of opto-chiasmatic arachnoiditis, which preoperatively can only be a tentative diagnosis that becomes final only when confirmed by surgical findings. In the presence of certain progressive neuro-ophthalmological symptoms and signs, a negative neuro-radiological investigation should not deter the neurosurgeon from exploring the chiasmatic region. Computer-assisted tomography, of which the authors have no personal experience in these cases, may hold the future answer to the diagnostic problem. [ABSTRACT FROM AUTHOR]

Copyright of Italian Journal of Neurological Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sputtering or ion impact desorption of adsorbed layers can be directly investigated by low-energy ion scattering. Because of its specific sensitivity to surface atoms, this method provides the possibility of monitoring the decrease of the signal from the adsorbate or the increase of the signal from the substrate. Both signals were studied with He backscattering from the system O on Ni (110). The measured desorption cross-sections and the principal implications for both ways of observation are discussed. The use of the substrate signal for the desorption study can be of major advantage, particularly in the case of light adsorbates. [ABSTRACT FROM AUTHOR]

Background: Forest management aims at obtaining a sustainable production of wood to be harvested to generate products or energy. However, the quantitative influence of forest management and of removals by harvest on biomass stocks has rarely been analysed on a large scale based on measurements. Two hypotheses prevail: management induces a reduction of wood stocks due to cuttings, versus no impact because of increased growth of the remaining trees. Using data collected for 2840 permanent plots across Romania from the National Forest Inventory representing ~ 2.5 Mha, we have tested to what extent different management types and treatments can influence the biomass stock and productivity of beech forests, and attempt to quantify these effects both on the short and long terms. Three main types of beech forest management are implemented in Romania with specific objectives: intensive wood production in production forests, protection of ecosystem services (e.g. watersheds, avalanche protection) in protection forests, and protection of the forest and its biodiversity in protected forests. Production forests encompass two treatments differing according to the stand regeneration method: the age class rotation management and the group shelterwood management. Results: We show that forest management had little influence on the biomass stocks at a given stand age. The highest stocks at stand age 100 were observed in production forests (the most intensively managed forests). Consequences of early cuttings were very short-termed because the increase in tree growth rapidly compensated for tree cuttings. The cumulated biomass of production forests exceeded that of protected and protection forests. Regarding the treatment, the group shelterwood forests had a markedly higher production over a full rotation period. The total amount of deadwood was primarily driven by the amount of standing deadwood, and no management effect was detected. Conclusions: Given the relatively low-intensity management in Romania, forest management had no negative impact on wood stocks in beech forests biomass stocks at large scale. Stand productivity was very similar among management types or treatments. However cumulated biomass in production forests was higher than in protection or protected forests, and differed markedly according to treatments with a higher cumulated biomass in shelterwood forests. [ABSTRACT FROM AUTHOR]