523 research outputs found
4-Lump kinetic model for hydrotreated gas oil catalytic cracking
This study has monitored the influence of one of the hydrodesulphurisation process parameters - H2/CH ratio on the properties of three catalytic cracking products (gas, petrol, light cyclic oil, and heavy cyclic oil ).
The microactivity test (MAT) was applied to all kinetic measurements. A 4-lump, non-isothermal and non-stationary kinetic model for the fixed, plug-flow MAT reactor was developed to model catalytic cracking of hydrotreated gas oil. Kinetic constants were estimated by the Nelder Mead method. The product yields predicted by the model showed good confirmity with experimental data
Coexistence of Superconductivity and Spin Density Wave orderings in the organic superconductor (TMTSF)_2PF_6
The phase diagram of the organic superconductor (TMTSF)_2PF_6 has been
revisited using transport measurements with an improved control of the applied
pressure. We have found a 0.8 kbar wide pressure domain below the critical
point (9.43 kbar, 1.2 K) for the stabilisation of the superconducting ground
state featuring a coexistence regime between spin density wave (SDW) and
superconductivity (SC). The inhomogeneous character of the said pressure domain
is supported by the analysis of the resistivity between T_SDW and T_SC and the
superconducting critical current. The onset temperature T_SC is practically
constant (1.20+-0.01 K) in this region where only the SC/SDW domain proportion
below T_SC is increasing under pressure. An homogeneous superconducting state
is recovered above the critical pressure with T_SC falling at increasing
pressure. We propose a model comparing the free energy of a phase exhibiting a
segregation between SDW and SC domains and the free energy of homogeneous
phases which explains fairly well our experimental findings.Comment: 13 pages, 10 figures, revised v: fig.9 added, section 4.2 rewritten,
accepted v: sections 4&5 improve
Anisotropic charge dynamics in the quantum spin-liquid candidate -(BEDT-TTF)Cu(CN)
We have in detail characterized the anisotropic charge response of the dimer
Mott insulator -(BEDT-TTF)\-Cu(CN) by dc conductivity, Hall
effect and dielectric spectroscopy. At room temperature the Hall coefficient is
positive and close to the value expected from stoichiometry; the temperature
behavior follows the dc resistivity . Within the planes the dc
conductivity is well described by variable-range hopping in two dimensions;
this model, however, fails for the out-of-plane direction. An unusually broad
in-plane dielectric relaxation is detected below about 60 K; it slows down much
faster than the dc conductivity following an Arrhenius law. At around 17 K we
can identify a pronounced dielectric anomaly concomitantly with anomalous
features in the mean relaxation time and spectral broadening. The out-of-plane
relaxation, on the other hand, shows a much weaker dielectric anomaly; it
closely follows the temperature behavior of the respective dc resistivity. At
lower temperatures, the dielectric constant becomes smaller both within and
perpendicular to the planes; also the relaxation levels off. The observed
behavior bears features of relaxor-like ferroelectricity. Because
heterogeneities impede its long-range development, only a weak tunneling-like
dynamics persists at low temperatures. We suggest that the random potential and
domain structure gradually emerge due to the coupling to the anion network.Comment: 14 pages, 13 figure
Cultural relativism and the discourse of intercultural communication: aporias of praxis in the intercultural public sphere
The premise of much intercultural communication pedagogy and research is to educate people from different cultures towards open and transformative positions of mutual understanding and respect. This discourse in the instance of its articulation realises and sustains Intercultural Communication epistemologically ā as an academic field of social enquiry, and judgementally ā as one which locates itself on a moral terrain. By adopting an ethical stance towards difference, the discourse of intercultural communication finds itself caught in a series of aporias, or performative contradictions, where interculturalists are projected simultaneously into positions of cultural relativism on the one hand and ideological totalism on the other. Such aporias arise because the theoretical premises upon which the discourse relies are problematic. We trace these thematics to a politics of presence operating within the discourse of intercultural communication and links this to questions of judgement and truth in the intercultural public sphere. We propose that the politics of presence be set aside in favour of an intercultural praxis which is oriented to responsibility rather than to truth
Magnetic Determination of under Accurate Alignment in (TMTSF)ClO
Cantilever magnetometry has been used to measure the upper critical magnetic
field of the quasi-one dimensional molecular organic superconductor
(TMTSF)ClO. From simultaneous resistivity and torque magnetization
experiments conducted under precise field alignment, at low
temperature is shown to reach 5T, nearly twice the Pauli paramagnetic limit
imposed on spin singlet superconductors. These results constitute the first
thermodynamic evidence for a large in this system and provide support
for spin triplet pairing in this unconventional superconductorComment: Submitted July 1, 2003, Accepted December 9, 2003, Physical Review
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Safety and Pharmacokinetics of a Four Monoclonal Antibody Combination Against Botulinum C and D Neurotoxins.
Botulism is caused by botulinum neurotoxin (BoNT), the most poisonous substance known. BoNTs are also classified as Tier 1 biothreat agents due to their high potency and lethality. The existence of seven BoNT serotypes (A-G), which differ between 35% to 68% in amino acid sequence, necessitates the development of serotype specific countermeasures. We present results of a Phase 1 clinical study of an anti-toxin to BoNT serotypes C and D, NTM-1634, which consists of an equimolar mixture of four fully human IgG1 monoclonal antibodies (mAbs), each binding to non-overlapping epitopes on BoNT serotypes C and D resulting in potent toxin neutralization in rodents. This first-in-human study evaluated the safety and pharmacokinetics of escalating doses of NTM-1634 administered intravenously to healthy adults (NCT03046550). Three cohorts of eight healthy subjects received a single intravenous dose of NTM-1634 or placebo at 0.33 mg/kg, 0.66 mg/kg or 1 mg/kg. Follow-up examinations and pharmacokinetic evaluations were continued up to 121 days post-infusion. Subjects were monitored using physical examinations, hematology and chemistry blood tests, and electrocardiograms. Pharmacokinetic parameters were estimated using noncompartmental methods. The results demonstrated that the materials were safe and well-tolerated with the expected half-lives for human mAbs and with minimal anti-drug antibodies detected over the dose ranges and duration of the study
Determination of the target nucleosides for members of two families of 16S rRNA methyltransferases that confer resistance to partially overlapping groups of aminoglycoside antibiotics
The 16S ribosomal RNA methyltransferase enzymes that modify nucleosides in the drug binding site to provide self-resistance in aminoglycoside-producing micro-organisms have been proposed to comprise two distinct groups of S-adenosyl-l-methionine (SAM)-dependent RNA enzymes, namely the Kgm and Kam families. Here, the nucleoside methylation sites for three Kgm family methyltransferases, Sgm from Micromonospora zionensis, GrmA from Micromonospora echinospora and Krm from Frankia sp. Ccl3, were experimentally determined as G1405 by MALDI-ToF mass spectrometry. These results significantly extend the list of securely characterized G1405 modifying enzymes and experimentally validate their grouping into a single enzyme family. Heterologous expression of the KamB methyltransferase from Streptoalloteichus tenebrarius experimentally confirmed the requirement for an additional 60 amino acids on the deduced KamB N-terminus to produce an active methyltransferase acting at A1408, as previously suggested by an in silico analysis. Finally, the modifications at G1405 and A1408, were shown to confer partially overlapping but distinct resistance profiles in Escherichia coli. Collectively, these data provide a more secure and systematic basis for classification of new aminoglycoside resistance methyltransferases from producers and pathogenic bacteria on the basis of their sequences and resistance profiles
Molecular characterization of old local grapevine varieties from South East European countries
South East European (SEE) viticulture partially relies on native grapevine varieties, previously scarcely described. In order to characterize old local grapevine varieties and assess the level of synonymy and genetic diversity from SEE countries, we described and genotyped 122 accessions from Albania, Federation of Bosnia and Herzegovina (B&H), Croatia, Macedonia, Moldova, Montenegro, Republika Srpska (Bosnia and Herzegovina) and Romania on nine most commonly used microsatellite loci. As a result of the study a total of 86 different genotypes were identified. All loci were very polymorphic and a total of 96 alleles were detected, ranging from 8 to 14 alleles per locus, with an average allele number of 10.67. Overall observed heterozygosity was 0.759 and slightly lower than expected (0.789) while gene diversity per locus varied between 0.600 (VVMD27) and 0.906 (VVMD28). Eleven cases of synonymy and three of homonymy have been recorded for samples harvested from different countries. Cultivars with identical genotypes were mostly detected between neighboring countries. No clear differentiation between countries was detected although several specific alleles were detected. The integration of the obtained genetic data with ampelographic ones is very important for accurate identification of the SEE cultivars and provides a significant tool in cultivar preservation and utilization.
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