The effect of oxygen on the aromatization of methane over the Mo/HZSM-5 catalyst

The aromatization of methane over a Mo/HZSM-5 catalyst was carried out in the presence of oxygen. It is shown that the addition of a small amount of oxygen is beneficial to improve the durability of the catalyst. UV-Raman spectra disclose that the carbonaceous deposits formed on the HZSM-5 are mainly polyolefinic and aromatic, while that on the Mo/HZSM-5 is mainly polyaromatic. The small amount of O-2 added may partly remove the coke deposits on the active sites and keep the catalyst as MoOxCy/HZSM-5, thus resulting in an improvement of the catalytic performance of the Mo/HZSM-5 catalyst.

Electrochromatographic evaluation of a silica monolith capillary column for separation of basic pharmaceuticals

A silica-based monolithic capillary column was prepared via a sol-gel process. The continuous skeleton and large through-pore structure were characterized by scanning electron microscopy (SEM). The native silica monolith has been successfully employed in the electrochromatographic separation of beta-blockers and alkaloids extracted from traditional Chinese medicines (TCMs). Column efficiencies greater than 250000 plates/m for capillary electrochromatography (CEC) separation of basic compounds were obtained. It was observed that retention of basic pharmaceuticals on the silica monolith was mainly contributed by a cation-exchange mechanism. Other retention mechanisms including reversed-phase and normal-phase mechanisms and electrophoresis of basic compounds also played a role in separation. A comparison of the differences between CEC and capillary zone electrophoresis (CZE) separation was also discussed.

Comparative X-ray photoelectron spectroscopic study on the desulfurization of thiophene by Raney Nickel and rapidly quenched skeletal nickel

The desulfurization of thiophene on Raney Ni and rapidly quenched skeletal Ni (RQ Ni) has been studied in ultrahigh vacuum (UHV) by X-ray photoelectron spectroscopy (XPS). The Raney Ni or RQ Ni can be approximated as a hydrogen-preadsorbed polycrystalline Ni-alumina composite. It is found that thiophene molecularly adsorbs on Raney Ni or RQ Ni at 103 K. At 173 K, thiophene on alumina is desorbed, while thiophene in direct contact with the metallic Ni in Raney Ni undergoes C-S bond scission, leading to carbonaceous species most probably in the metallocycle-like configuration and atomic sulfur. On RQ Ni, the temperature for thiophene dissociation is about 100 K higher than that on Raney Ni. The lower reactivity of RQ Ni toward thiophene is tentatively attributed to lattice expansion of Ni crystallites in RQ Ni due to rapid quenching. The existence of alumina and hydrogen may block the further cracking of the metallocycle-like species on Raney Ni and RQ Ni at higher temperatures, which has been the dominant reaction pathway on Ni single crystals. By 473 K, the C Is peak has disappeared, leaving nickel sulfide on the surface.

Volumetric consequences of particle loss by grading entropy.

Chemical and biological processes, such as dissolution in gypsiferous sands and biodegradation in waste refuse, result in mass or particle loss, which in turn lead to changes in solid and void phase volumes and grading. Data on phase volume and grading changes have been obtained from oedometric dissolution tests on sand–salt mixtures. Phase volume changes are defined by a (dissolution-induced) void volume change parameter (Λ). Grading changes are interpreted using grading entropy coordinates, which allow a grading curve to be depicted as a single data point and changes in grading as a vector quantity rather than a family of distribution curves. By combining Λ contours with pre- to post-dissolution grading entropy coordinate paths, an innovative interpretation of the volumetric consequences of particle loss is obtained. Paths associated with small soluble particles, the loss of which triggers relatively little settlement but large increase in void ratio, track parallel to the Λ contours. Paths associated with the loss of larger particles, which can destabilise the sand skeleton, tend to track across the Λ contours.

Analyses of patterns of copper and lead mineralisation in human skeletons excavated from an ancient mining and smelting centre in the Jordanian desert

Grattan, J.P., Al-Saad, Z., Gilbertson, D.D., Karaki, L.O., Pyatt, F.B 2005 Analyses of patterns of copper and lead mineralisation in human skeletons excavated from an ancient mining and smelting centre in the Jordanian desert Mineralogical Magazine. 69(5) 653-666.

Tectonics Inversions & Emerald Deposits

In spite of the great amount of emerald deposits throughout the world, the priorities in quality and volume of extracted rough material are the sites of Colombia (Muzo and Chivor emerald belts). This sites are know even before the Spanish conquistadores. Emeralds were extracted from Somondoco mine (today Chivor) since 1537 and from Muzo in 1567. Contrariwise to the majority of the emerald deposits of the world, which are associated with granitic rocks, the Colombian emerald deposits are associated with hydrofracturing (the main factor controlling emerald mineralization) and hydrothermal fluids, rich in beryl, chrome and vanadium, induced by a tectonic inversion of the deep Mesozoic backarc basin, which is also responsible of the majority of the petroleum systems of the foredeep and foldbelt areas (maturation of the source-rocks andcreation of structural traps). The host rocks of the emeralds are carbonaceous calsiltites (calcareous schists) rich in organic matter of Lower Cretaceous age, which are cut by calcite veins, which, often, contain emeralds, particularly when they are folded. Indeed, since long time (Cheilletz, A. and Giulliani, G., 1996) suggested a two-stage model for the formation of the Colombian emeralds : (i) Stage I is characterized by décollement planes (early compressional tectonic regime) within the carbonaceous calsiltites, hydrothermal fluid infiltration and wall-rock metasomatic alteration ; (ii) Stage II (late tectonic regime) deforms the previous veins by thrust-related folds (development of stratiform and hydraulic breccia), which are synchronous of the emerald mineralization. The resulting tectonic structures are complex fold patterns characterized by propagation anticlines with emerald veins and emerald hydraulic breccia in the apexes, as in Quipama, Tendenquema and Chivor mines. Otherwise stated, since all emerald exploitations are, presently underground, exhaustive geological and particularly structural studies are required to reduce the probability of disappointments. The color of emeralds is from light green to thick green with obvious pleochroism. They appears with different colors when observed at different angles, especially with polarized light. The emeralds from Coscuez deposits have a homogeneous intensive color and bluish tone. At Muzo deposit, the emeralds have middle or dark green color with yellowish tone. At the Chivor deposits, the emeralds have less intensive green color with slight bluish tone. The typical inclusions are albite and pyrite, as well as long bubbles with three phase-inclusions according the zones of growth and along the crystal shapes.

Ryanodine receptor expression in trophoblasts

Trophoblasts of the placenta are the frontline cells involved in communication and exchange of materials between the mother and fetus. Within trophoblasts, calcium signalling proteins are richly expressed. Intracellular free calcium ions are a key second messenger, regulating various cellular activities. Transcellular Ca2+ transport through trophoblasts is essential in fetal skeleton formation. Ryanodine receptors (RyRs) are high conductance cation channels that mediate Ca2+ release from intracellular stores to the cytoplasm. To date, the roles of RyRs in trophoblasts have not been reported. By use of reverse transcription PCR and western blotting, the current study revealed that RyRs are expressed in model trophoblast cell lines (BeWo and JEG-3) and in human first trimester and term placental villi. Immunohistochemistry of human placental sections indicated that both syncytiotrophoblast and cytotrophoblast cell layers were positively stained by antibodies recognising RyRs; likewise, expression of RyR isoforms was also revealed in BeWo and JEG-3 cells by immunofluorescence microscopy. In addition, changes in [Ca2+]i were observed in both BeWo and JEG-3 cells upon application of various RyR agonists and antagonists, using fura-2 fluorescent videomicroscopy. Furthermore, endogenous placental peptide hormones, namely angiotensin II, arginine vasopressin and endothelin 1, were demonstrated to increase [Ca2+]i in BeWo cells, and such increases were suppressed by RyR antagonists and by blockers of the corresponding peptide hormone receptors. These findings indicate that 1) multiple RyR subtypes are expressed in human trophoblasts; 2) functional RyRs in BeWo and JEG-3 cells response to both RyR agonists and antagonists; 3) RyRs in BeWo cells mediate Ca2+ release from intracellular store in response to the indirect stimulation by endogenous peptides. These observations suggest that RyR contributes to trophoblastic cellular Ca2+ homeostasis; trophoblastic RyRs are also involved in the functional regulation of human placenta by coupling to endogenous placental peptide-induced signalling pathways.

Development of low-cost sensing and separation devices based on macro, micro and nano technology for health applications

The work presented in this thesis described the development of low-cost sensing and separation devices with electrochemical detections for health applications. This research employs macro, micro and nano technology. The first sensing device developed was a tonerbased micro-device. The initial development of microfluidic devices was based on glass or quartz devices that are often expensive to fabricate; however, the introduction of new types of materials, such as plastics, offered a new way for fast prototyping and the development of disposable devices. One such microfluidic device is based on the lamination of laser-printed polyester films using a computer, printer and laminator. The resulting toner-based microchips demonstrated a potential viability for chemical assays, coupled with several detection methods, particularly Chip-Electrophoresis-Chemiluminescence (CE-CL) detection which has never been reported in the literature. Following on from the toner-based microchip, a three-electrode micro-configuration was developed on acetate substrate. This is the first time that a micro-electrode configuration made from gold; silver and platinum have been fabricated onto acetate by means of patterning and deposition techniques using the central fabrication facilities in Tyndall National Institute. These electrodes have been designed to facilitate the integration of a 3- electrode configuration as part of the fabrication process. Since the electrodes are on acetate the dicing step can automatically be eliminated. The stability of these sensors has been investigated using electrochemical techniques with excellent outcomes. Following on from the generalised testing of the electrodes these sensors were then coupled with capillary electrophoresis. The final sensing devices were on a macro scale and involved the modifications of screenprinted electrodes. Screen-printed electrodes (SPE) are generally seen to be far less sensitive than the more expensive electrodes including the gold, boron-doped diamond and glassy carbon electrodes. To enhance the sensitivity of these electrodes they were treated with metal nano-particles, gold and palladium. Following on from this, another modification was introduced. The carbonaceous material carbon monolith was drop-cast onto the SPE and then the metal nano-particles were electrodeposited onto the monolith material

Real time analysis of atmospheric single particles in urban environments using aerosol time of flight mass spectrometry

In order to determine the size-resolved chemical composition of single particles in real-time an ATOFMS was deployed at urban background sites in Paris and Barcelona during the MEGAPOLI and SAPUSS monitoring campaigns respectively. The particle types detected during MEGAPOLI included several carbonaceous species, metal-containing types and sea-salt. Elemental carbon particle types were highly abundant, with 86% due to fossil fuel combustion and 14% attributed to biomass burning. Furthermore, 79% of the EC was apportioned to local emissions and 21% to continental transport. The carbonaceous particle types were compared with quantitative measurements from other instruments, and while direct correlations using particle counts were poor, scaling of the ATOFMS counts greatly improved the relationship. During SAPUSS carbonaceous species, sea-salt, dust, vegetative debris and various metal-containing particle types were identified. Throughout the campaign the site was influenced by air masses altering the composition of particles detected. During North African air masses the city was heavily influenced by Saharan dust. A regional stagnation was also observed leading to a large increase in carbonaceous particle counts. While the ATOFMS provides a list of particle types present during the measurement campaigns, the data presented is not directly quantitative. The quantitative response of the ATOFMS to metals was examined by comparing the ion signals within particle mass spectra and to hourly mass concentrations of; Na, K, Ca, Ti, V, Cr, Mn, Fe, Zn and Pb. The ATOFMS was found to have varying correlations with these metals depending on sampling issues such as matrix effects. The strongest correlations were observed for Al, Fe, Zn, Mn and Pb. Overall the results of this work highlight the excellent ability of the ATOFMS in providing composition and mixing state information on atmospheric particles at high time resolution. However they also show its limitations in delivering quantitative information directly.

Anti-AIDS agents 81. Design, synthesis, and structure-activity relationship study of betulinic acid and moronic acid derivatives as potent HIV maturation inhibitors.

In our continuing study of triterpene derivatives as potent anti-HIV agents, different C-3 conformationally restricted betulinic acid (BA, 1) derivatives were designed and synthesized in order to explore the conformational space of the C-3 pharmacophore. 3-O-Monomethylsuccinyl-betulinic acid (MSB) analogues were also designed to better understand the contribution of the C-3' dimethyl group of bevirimat (2), the first-in-class HIV maturation inhibitor, which is currently in phase IIb clinical trials. In addition, another triterpene skeleton, moronic acid (MA, 3), was also employed to study the influence of the backbone and the C-3 modification toward the anti-HIV activity of this compound class. This study enabled us to better understand the structure-activity relationships (SAR) of triterpene-derived anti-HIV agents and led to the design and synthesis of compound 12 (EC(50): 0.0006 microM), which displayed slightly better activity than 2 as a HIV-1 maturation inhibitor.

Effect of peak inert-mode temperature on elemental carbon measured using thermal-optical analysis

Thermal-optical analysis is a conventional method for classifying carbonaceous aerosols as organic carbon (OC) and elemental carbon (EC). This article examines the effects of three different temperature protocols on the measured EC. For analyses of parallel punches from the same ambient sample, the protocol with the highest peak helium-mode temperature (870°C) gives the smallest amount of EC, while the protocol with the lowest peak helium-mode temperature (550°C) gives the largest amount of EC. These differences are observed when either sample transmission or reflectance is used to define the OC/EC split. An important issue is the effect of the peak helium-mode temperature on the relative rate at which different types of carbon with different optical properties evolve from the filter. Analyses of solvent-extracted samples are used to demonstrate that high temperatures (870°C) lead to premature EC evolution in the helium-mode. For samples collected in Pittsburgh, this causes the measured EC to be biased low because the attenuation coefficient of pyrolyzed carbon is consistently higher than that of EC. While this problem can be avoided by lowering the peak helium-mode temperature, analyses of wood smoke dominated ambient samples and levoglucosan-spiked filters indicate that too low helium-mode peak temperatures (550°C) allow non-light absorbing carbon to slip into the oxidizing mode of the analysis. If this carbon evolves after the OC/EC split, it biases the EC measurements high. Given the complexity of ambient aerosols, there is unlikely to be a single peak helium-mode temperature at which both of these biases can be avoided. Copyright © American Association for Aerosol Research.

An approach to monitor the fraction of elemental carbon in the ultrafine aerosol

Attempts were made to measure the fraction of elemental carbon (EC) in ultrafine aerosol by modifying an Ambient Carbonaceous Particulate Monitor (ACPM, R&P 5400). The main modification consisted in placing a quartz filter in one of the sampling lines of this dual-channel instrument. With the filter all aerosol and EC contained in it is collected, while in the other line of the instrument the standard impactor samples only particles larger than 0.14 μm. The fraction of EC in particles smaller than 0.14 μm is derived from the difference in concentration as measured via the two sampling lines. Measurements with the modified instrument were made at a suburban site in Amsterdam, The Netherlands. An apparent adsorption artefact, which could not be eliminated by the use of denuders, precluded meaningful evaluation of the data for total carbon. Blanks in the measurements of EC were negligible and the EC data were hence further evaluated. We found that the concentration of EC obtained via the channel with the impactor was systematically lower than that in the filter-line. The average ratio of the concentrations was close to 0.6, which indicates that approximately 40% of the EC was in particles smaller than 0.14 μm. Alternative explanations for the difference in the concentration in the two sampling lines could be excluded, such as a difference in the extent of oxidation. This should be a function of loading, which is not the case. Another reason for the difference could be that less material is collected by the impactor due to rebound, but such bounce of aerosol is very unlikely in The Netherlands due to co-deposition of abundant deliquesced and thus viscous ammonium compounds. The conclusion is that a further modification to assess the true fraction of ultrafine EC, by installing an impactor with cut-off diameter at 0.1 μm, would be worth pursuing. © 2005 Elsevier Ltd. All rights reserved.

A unified anatomy ontology of the vertebrate skeletal system.

The skeleton is of fundamental importance in research in comparative vertebrate morphology, paleontology, biomechanics, developmental biology, and systematics. Motivated by research questions that require computational access to and comparative reasoning across the diverse skeletal phenotypes of vertebrates, we developed a module of anatomical concepts for the skeletal system, the Vertebrate Skeletal Anatomy Ontology (VSAO), to accommodate and unify the existing skeletal terminologies for the species-specific (mouse, the frog Xenopus, zebrafish) and multispecies (teleost, amphibian) vertebrate anatomy ontologies. Previous differences between these terminologies prevented even simple queries across databases pertaining to vertebrate morphology. This module of upper-level and specific skeletal terms currently includes 223 defined terms and 179 synonyms that integrate skeletal cells, tissues, biological processes, organs (skeletal elements such as bones and cartilages), and subdivisions of the skeletal system. The VSAO is designed to integrate with other ontologies, including the Common Anatomy Reference Ontology (CARO), Gene Ontology (GO), Uberon, and Cell Ontology (CL), and it is freely available to the community to be updated with additional terms required for research. Its structure accommodates anatomical variation among vertebrate species in development, structure, and composition. Annotation of diverse vertebrate phenotypes with this ontology will enable novel inquiries across the full spectrum of phenotypic diversity.

PenPC: A two-step approach to estimate the skeletons of high-dimensional directed acyclic graphs.

Estimation of the skeleton of a directed acyclic graph (DAG) is of great importance for understanding the underlying DAG and causal effects can be assessed from the skeleton when the DAG is not identifiable. We propose a novel method named PenPC to estimate the skeleton of a high-dimensional DAG by a two-step approach. We first estimate the nonzero entries of a concentration matrix using penalized regression, and then fix the difference between the concentration matrix and the skeleton by evaluating a set of conditional independence hypotheses. For high-dimensional problems where the number of vertices p is in polynomial or exponential scale of sample size n, we study the asymptotic property of PenPC on two types of graphs: traditional random graphs where all the vertices have the same expected number of neighbors, and scale-free graphs where a few vertices may have a large number of neighbors. As illustrated by extensive simulations and applications on gene expression data of cancer patients, PenPC has higher sensitivity and specificity than the state-of-the-art method, the PC-stable algorithm.

Metastatic bone disease

The skeleton is the first and most common site of distant relapse in breast and prostate carcinomas. Tumor bone disease is responsible for a considerable morbidity, which also makes major demands on resources for healthcare provision. Increased bone resorption in tumor bone disease appears to be essentially mediated by the ostoclasts, explaining why bisphosphonates have been successfully used for the treatment of malignant ostolysis. Hypercalcemia occurs in 10-20% of the patients with advanced cancer, and the uncoupling between bone resorption and bone formation is easily demonstrated by the measurement of bone markers. The differential diagnosis between tumor-induced hypercalcemia and primary hyperparathyroidism is most often easy when using intact parathyroid hormone (PTH) assays; moreover, parathyroid hormone-related protein (PTHrP) determination can be useful in selected cases. The diagnosis of bone metastases is often easy when the patient is symptomatic. The diagnostic usefulness of bone markers is limited, and the available data indicate that bone markers are so far unsuitable for an early diagnosis of neoplastic skeletal involvement on an individual basis. However, by combining bone-specific alkaline phosphatase (BALP) or modern bone resorption markers with specific tumor markers, such as PSA or CA15.3, the diagnostic sensitivity of bone markers can be improved. Their degree of elevation correlates with the tumor burden and has been shown to be an independent prognostic factor for several tumors. On the other hand, biochemical markers of bone turnover have the unique potential to simplify and improve the monitoring of metastatic bone disease, which remains a continuous challenge for the oncologist. Peptide-bound cross-links could be quite useful to discriminate between patients progressing early on treatment from those with longer disease control. Also, the diagnostic efficiency of a 50% increase in these markers could identify imminent progression. © 2006 Elsevier Inc. All rights reserved.