bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of a rotating shaft—disc under a periodic axial force
Authors: Pei Yong-Chen , Lu H , Chatwin C
Published: October 2009

Under a periodic axial force, a rotating Timoshenko shaft with a rigid unsymmetrical disc was modelled as a parametrically excited system using the finite-element method. Using a harmonic balance method, dynamic stability of the system was checked, steady-state response, undamped resonance condition, and disc centre orbit were solved analytically and discussed numerically. Furthermore, the time history response was calculated to verify the efficiency of the solutions. The discussion shows that the fluctuating part of the axial force results in system dynamic instability, and the parameter regions of dynamic instability are enlarged with increasing amplitude of the fluctuation; the disc centre orbit of the system steady-state response is limited to an annular region, and the orbit width is increased by the axial force fluctuating amplitude; besides the neighbourhood of the system critical speed, the shaft—disc system can undergo some additional resonances due to the fluctuating axial force.
Dynamic analysis of gear pairs with a gross motion effect using the dynamic stiffness matrix method
Authors: Huang K J
Published: October 2009

A continuum approach using the dynamic stiffness matrix (DSM) method (DSMM) is presented for the dynamic analyses of spur gear pairs incorporating the gross motion effect. A continuum dynamic model of spur gears was formulated based on the dynamic stiffness using the non-uniform Timoshenko beam theory. A systematic DSM for a gear pair was assembled including the elemental DSMs of two mating gears and non-linear Hertzian contact stiffness. The DSMs were updated at each computing step to reflect the time-varying property due to the moving mesh points. A bisection procedure was used to calculate the natural frequencies as the systematic DSM of the gear pair became singular. The mass and stiffness matrices were calculated by taking a numerical derivative of the systematic DSM. Finally, the gear dynamic responses caused by the external torque and gross motion excitation resulted. The effect of gross motion is also discussed.
Research on the orientation-singularity and orientation-workspace of a class of Stewart—Gough parallel manipulators
Authors: Cao Y , Zhou H , Zhang Q-J , Ji W-X
Published: October 2009

This article addresses the orientation-singularity analysis and orientation-workspace computation of a class of Stewart—Gough manipulators in which the moving and base platforms are two similar semisymmetrical hexagons. Based on the half-angle transformation, a polynomial expression of 13 degrees that represents the orientation-singularity locus of this class of Stewart—Gough manipulators at a fixed position is derived, and graphical representations of the orientation-singularity locus of this class of Stewart—Gough manipulators are illustrated with examples to demonstrate the result. Using this half-angle transformation, a discretization method is proposed for computing the orientation-workspace of this class of Stewart—Gough manipulators taking limitations of active and passive joints and the link interference into consideration. In addition, this article also presents a new discretization method for the computation of the non-singular orientation-workspace of this class of Stewart—Gough manipulators, where singularities, limitations of active and passive joints, and the link interference are all taken under consideration. The non-singular orientation-workspace can not only satisfy the kinematics demand of this class of Stewart—Gough parallel manipulators, but also can guarantee that the manipulator is non-singular in the whole orientation-workspace. Examples of a 6/6-SPS Stewart—Gough manipulator of this class are given to demonstrate the results.
Terahertz Time-Domain Spectroscopy of Selected Layered Silicates
Authors: Janek Marián , Bugár Ignác , Lorenc Dušan , Szöcs Vojtech , Velič Dušan , Chorvát Dušan
Published: October 2009

Micaceous layer silicate clay minerals are attractive materials for applications involving non-linear optics because of their low cost and ability to form well ordered, platy aggregates, but such applications require precise knowledge of the dielectric behavior of the clay. The purpose of the present study was to use Terahertz time-domain spectroscopy (THz-TDS) to determine the dielectric properties of certain cleavable layered clay minerals, including muscovite, vermiculite, phlogopite, and biotite. The samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy as well as chemical analysis by Energy dispersive X-ray spectroscopy. The THz frequency window investigated was the far-infrared region of 3.3 to ∼40.0 cm−1 corresponding to 0.1 and 1.2 THz, respectively. The samples were selected so that the hydrated form of the interlayer cation, e.g. Mg2+ present in the interlayer gallery of vermiculite, could be compared to species such as phlogopite, biotite, and muscovite with the dehydrated form of interlayer cations such as K+ or Na+. The frequency-dependent complex index of refraction of these natural materials was determined to vary between 2.50 and 2.80. The presence of water in the interlayer space of vermiculite was reflected in the detection of increased values of the absorption index in comparison with the muscovite, phlogopite, and biotite.
The Formation of Layered Double Hydroxides on Alumina Surface in Aqueous Solutions Containing Divalent Metal Cations
Authors: Kovanda František , Mašátová Petra , Novotná Petra , Jirátová Květa
Published: October 2009

Layered double hydroxides (LDHs) are often used as precursors for mixed-oxide catalysts and the deposition of a LDH layer on supporting materials would be advantageous because of better utilization of active components. The purpose of the present study was to investigate the formation of LDHs on Al2O3/Al supports prepared by the anodic oxidation of aluminum foil in dilute aqueous solutions of Co, Mn, and/or Ni nitrates. The LDH deposition was carried out under hydrothermal conditions at 80–180°C for periods ranging from 8 h to 7 days. In the initial stages of the reaction, a surface alumina hydration was observed. The LDH phase was detected after long-term deposition (3–7 days) at 120–160°C and only a small amount of Mn was incorporated in the LDHs deposited. In solutions containing only Co and Mn cations, scanning electron microscopy (SEM) images show a gradual growth of platy crystals resulting in the formation of discrete bulky aggregates with sizes up to several tens of micrometers. The adhesion of aggregates to the support probably decreased with increasing size and oversized aggregates fell away; none was found in SEM images of the samples obtained after prolonged reaction times. When Ni cations were present in the solution, they were incorporated preferentially into the LDH phase; an homogeneous layer was formed, with single platy crystals oriented perpendicular to the support. After calcination at 500°C, the products formed on Al2O3/Al support exhibited a shift of reduction maxima to higher temperatures in comparison with mixed oxides obtained by thermal decomposition of coprecipitated LDHs.
Magnetic Titanium-Pillared Clays (Ti-M-PILC): Magnetic Studies and Mössbauer Spectroscopy
Authors: Bachir Cherifa , Lan Yanhua , Mereacre Valeriu , Powell Annie K. , Koch Christian Bender , Weidler Peter G.
Published: October 2009

Pillared clays (PILCs) with magnetic properties are materials with potential for wide application in industry and the environment, but only a few studies of these types of materials have been carried out. The purpose of this study was to advance knowledge of the preparation and magnetic properties of pillared clays by examining in detail a series of magnetic Ti-pillared clays (Ti-M-PILCs). Samples were synthesized at ambient temperature by sodium borohydride reduction of ferrous ions added by ion-exchange to Ti-pillared montmorillonite (Ti-PILCs). The properties of the Ti-M-PILCs were investigated using a superconducting quantum interference device (SQUID) and Mössbauer spectroscopy. Hysteresis, zero-field-cooled (ZFC), and field-cooled (FC) regimes were measured on different precursor materials prepared by calcination of Ti-PILCs at temperatures between 200 and 600°C. Hysteresis loops, recorded between −7 and 7 T in the temperature range 200–300 K, were observed in most samples depending on the preparation of clays. The ZFC/FC measurements were made after heating from 2 to 300 Kunder an applied magnetic field of 39.8 kA m−1. The influence of the calcination temperature of the starting Ti-PILCs on the structural and magnetic properties of the Ti-M-PILCs was examined. The presence of two different Fe-alloy distributions was found; a dispersed one for the less-calcined Ti-PILCs and clusters for the more-calcined ones.
Natural Rubber Nanocomposites With Organo-Modified Bentonite
Authors: Hrachová Jana , Komadel Peter , Chodák Ivan
Published: October 2009

Enhancement of the physico-chemical properties of elastomers can be achieved by the addition of fillers, such as silica, but the search for less expensive alternative materials continues. The objective of this study was to investigate natural or organically modified clay minerals as such an alternative. Organo-clays modified by quaternary ammonium cations with three methyl groups and longest alkyl chains of different lengths were prepared by ion-exchange reaction of the commercial product JP A030 (Envigeo, Slovakia) based on Jelšový Potok bentonite with organic salts: tetramethylammonium (TMA) chloride, octyltrimethylammonium (OTMA) bromide, and octadecyltrimethylammonium (ODTMA) bromide. Physico-chemical characterizations of the organo-clays used as fillers in rubber nanocomposites and their mechanical properties were measured using Fourier transform infrared (IR) spectroscopy, which provided information on the chemical composition of the mineral and on the amount of organic moieties adsorbed. X-ray diffraction analysis (XRD) was used to monitor the arrangement of organic chains in galleries of montmorillonite and showed that the longest-chain alkylammonium ODTMA+ ions were intercalated between layers, adopting a pseudotrimolecular conformation, while OTMA+ and TMA+ were in monomolecular arrangement. Surface areas were measured by sorption of N2 and ethylene glycol monoethyl ether. Natural rubber-clay nanocomposites were prepared by melt intercalation, in some cases also with addition of silica, a conventional reinforcing filler. The microstructure of montmorillonite in these composites was characterized by XRD analysis. The effect of clay and organo-clays loading from 1 to 10 phr (parts by weight per hundred parts of rubber) on stress at break, strain at break, and Modulus 100 (M100) was investigated by tensile tests. Filler ODTMA-JP A030 appears to be the most effective among the organoclays; surprisingly similar values of composite elongation and strength were obtained with unmodified bentonite JP A030.
The Effect of Structural Order on Nanotubes Derived From Kaolin-Group Minerals
Authors: Matusik Jakub , Gaweł Adam , Bielańska Elżbieta , Osuch Władysław , Bahranowski Krzysztof
Published: October 2009

Kaolin-group clay minerals can be modified to form nanotubular and mesoporous structures with interesting catalytic properties, but knowledge of the best methods for preparing these structures is still incomplete. The objective of this study was to investigate intercalation/deintercalation as a method for the delamination and rolling of kaolinite layers in relation to structural order. To prepare nanotubular material, kaolinites of different crystallinities and halloysite (all from Polish deposits) were chosen. The experimental procedure consisted of four stages: (1) preparation of a dimethyl sulfoxide precursor intercalate; (2) interlayer grafting with 1,3-butanediol; (3) hexylamine intercalation; and (4) deintercalation of amine-intercalated minerals using toluene as the solvent. Structural perturbations and changes in the morphology of the minerals were examined by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy (TEM). The number of rolled kaolinite layers depended heavily on the efficiency of the intercalation steps. An increase in the structural disorder and extensive delamination of the minerals subjected to chemical treatment were recorded. Kaolinite particles which exhibited tubular morphology or showed rolling effects were observed using TEM. The nanotubes formed were ∼30 nm in diameter, with their length depending on the particle sizes of the minerals.
High-Resolution Transmission Electron Microscopy Study of Fe-Mn Oxides in the Hydrothermal Sediments of the Red Sea Deeps System
Authors: Taitel-Goldman Nurit , Ezersky Vladimir , Mogilyanski Dimitry
Published: October 2009

Deep sediments from the Red Sea have been studied extensively and provide a rich resource for understanding mineral transformations under hydrothermal conditions. Interrelationships among various sampling sites, however, are still rather incomplete. The purpose of the present study was to increase understanding of these systems by characterizing and comparing the Fe-Mn oxyhydroxides from the southern Atlantis II, Chain A, Chain B, and Discovery Deeps, using high-resolution transmission electron microscopy. Some of the hydrothermal sediments of Chain A are dominated by Si-associated Fe oxides (ferrihydrite, goethite, lepidocrocite, and short-range ordered, rounded particles) resembling the hydrothermal sediments of the SW basin in the Atlantis II Deep, indicating sub-bottom connections between the Deeps. Although some of the sediments of the Discovery Deep show a similar trend; short-range ordered, rounded particles were not detected in these sediments, implying that crystallization of this short-range ordered phase is sensitive to the Si/Fe ratio in the brine and only at elevated ratios does it crystallize out of the brine. Silicon-associated and Fe-enriched Mn oxyhydroxides such as groutite, manganite, todorokite, and Mn-dominated lathlike layers occasionally contain Ca and Mg impurities. Manganese substitutes for Fe and vice versa, leading to a solid-solution series between goethite and groutite and Mn-enriched ferrihydrite. Hematite is the only Fe oxide in the hydrothermal sediments that is found to be lacking in impurities, which is probably due to its formation by recrystallization from other Fe oxides.
Optimizing the Mechanical Strength of Adobe Bricks
Authors: Schicker A. , Gier S.
Published: October 2009

Ecologic building materials such as adobe bricks have become of greater economic importance in recent years. In the present work, the addition of selected materials to improve the compressive and bending strengths of adobe bricks was tested. The raw material (loam UD) was analyzed for its mineralogical and chemical composition. The loam studied consisted of quartz, feldspar, and the clay minerals chlorite, vermiculite, illite, and kaolinite. Prerequisites for using this loam for brick making were its grain-size distribution and the absence of expandable clay minerals.

To optimize the compressive and bending strengths of the adobe bricks, seven natural and ‘eco-friendly’ synthetic additives were admixed with the raw material and homogenized.

From this material, small adobe bricks and bars were made. One series of bricks and bars was made without additives but instead was coated with a hydrophobic impregnation cream. The bricks were stored for up to 20 days at 100 and 75% relative humidity (RH). After 1, 5, and 20 days, the compressive and bending strengths were measured to identify the critical humidity level for brick strength. The compressive and bending strengths of loam UD at dry conditions without additives showed values of 9 N/mm2 and 4.8 N/mm2, respectively. With some of the additives, the strength improved by up to 30%. The greatest increases in strength were achieved by mixing the loam with Acronal S650. Finely ground trass and diatomite also increased the dry strength. After storage at high levels of RH, these mixtures lost >50% strength. In contrast, the loam mixed with blast-furnace slag has a small initial strength but showed the smallest decreases in strength after exposure to high levels of RH.
Adsorption of a C10E3 Non-Ionic Surfactant on a Ca-Smectite
Authors: Guegan Regis , Gautier Mathieu , Beny Jean-Michel , Muller Fabrice
Published: October 2009

The transformation of clay minerals into organo-clays by surfactant intercalation is of great environmental and industrial importance because it causes the clay to attract hydrophobic contaminants and other non-polar organic compounds, but a better understanding is needed of the mechanisms by which different classes of surfactants are intercalated. The purpose of this study was to synthesize and characterize an organo-clay comprising triethylene glycol monodecyl ether (C10E3) non-ionic surfactant, which has a lamellar phase at room temperature, intercalated into Ca-montmorillonite from Wyoming (SWy-2). The C10E3 non-ionic surfactant differed from previous non-ionic surfactants used in the formation of a lamellar phase in that it consisted of the stacking of molecules by hydrophobic interaction. C10E3-clay composites were characterized by complementary techniques (adsorption isotherms, X-ray diffraction, and infrared spectroscopy) and were compared to benzyldimethyltetradecyl ammonium chloride (BDTAC) cationic surfactant-clay composites for different loadings of the surfactant. For large loadings, the amount of C10E3 adsorbed, which can be described by the Langmuir equation, seemed to reach a steady state close to that of the cationic surfactant. The adsorption processes of the two surfactants were different. For the cationic surfactant, the adsorption, as described in the literature, was due to ion exchange between organic cations and Ca2+ counterions. The adsorption of C10E3 did not depend on electrostatic interaction but rather was due to several interaction mechanisms (H-bonding, ion-dipole, and hydrophobic interaction). For both surfactants, the expansion was limited to two adsorbed monolayers parallel to the clay surface. The expansion of the basal spacing to 17 Å suggested a complete dissociation of the C10E3 lamellar phase when adsorbed on the Ca-smectite. Organo-clays made using the non-ionic surfactant were stable, changing the chemical nature of clay to hydrophobic, and allowing for other cations to be exchanged, which has importance in the manufacture of new nanocomposites or geochemical barriers.
The pituitary–adrenal axis in adult thalassaemic patients
Authors: Scacchi Massimo , Danesi Leila , Cattaneo Agnese , Valassi Elena , Pecori Giraldi Francesca , Radaelli Piero , Ambrogio Alberto , D'Angelo Emanuela , Mirra Nadia , Zanaboni Laura , Cappellini Maria D , Cavagnini Francesco
Published: October 2009

Objective

We previously described in young thalassaemic patients an altered cortisol and ACTH responsiveness suggesting an impaired adrenocortical reserve. Owing to iron overload, a worsening of adrenal function should be expected in adult patients.

Design

In 124 adults with β-thalassaemia, urinary free cortisol (UFC) and plasma ACTH levels were determined and compared with those measured in 150 controls. In 45 patients, cortisol was measured in response to: i) tetracosactide 1 μg as an i.v. bolus (low-dose test, LDT) and ii) tetracosactide 250 μg infused i.v. over 8 h (high-dose test, HDT).

Results

UFC and serum cortisol were within the reference range in all patients. Conversely, basal plasma ACTH values were above the upper limit of the normal range in 19 patients. There were no statistically significant differences in the mean values of UFC, basal serum cortisol and plasma ACTH between patients and controls. A subnormal cortisol response to the LDT was registered in 18 out of 56 patients. Three of these patients also displayed a subnormal response to the HDT, together with elevated baseline plasma ACTH levels. In the LDT, a positive correlation was found between basal and peak cortisol values (P<0.0001). The latter were negatively correlated with basal ACTH values in both LDT (P<0.0001) and HDT (P<0.0001).

Conclusions

Adult thalassaemic patients often present a subtle impairment of adrenocortical function. This may become clinically relevant in case of major stressful events. Thus, we recommend an assessment of adrenocortical function in all adult thalassaemic patients.
The role of real-time three-dimensional echocardiography in the evaluation of hypertrophic cardiomyopathy
Authors: Nemes Attila , Geleijnse Marcel L. , Soliman Osama I. I. , Anwar Ashraf M. , Vletter Wim B. , McGhie Jackie S. , Csanády Miklós , Forster Tamás , Ten Cate Folkert J.
Published: October 2009

A hypertrophiás cardiomyopathia egy relatíve gyakori öröklődő betegség, amely sajátos kardiális morfológiai és funkcionális eltérésekkel jár együtt. Az echokardiográfia a cardiomyopathiás betegek noninvazív vizsgálatának egyszerű, könnyen kivitelezhető és megtanulható módszereként szolgál. Ennek az összefoglaló jellegű közleménynek a célja az egyik legújabb echokardiográfiás fejlesztés, a real-time háromdimenziós echokardiográfia lehetséges diagnosztikus szerepének bemutatása hypertrophiás cardiomyopathiában.
The value of routine second-look endoscopy in the management of the acute gastroduodenal ulcer bleeding
Authors: Szőcs Katalin , Kárász Tibor , Saleh Hussam , Szabó Andrea , Csöndes Mihály , Dancs Nóra , Jánoki Márta , Horváth Zoltán , Rácz István
Published: October 2009

A tervezett ellenőrző endoszkópiák szerepe az akut gastroduodenalis fekélyvérző betegek ellátásában mindmáig ellentmondásos. Endoszkópos és klinikai adatokra alapozott rizikócsoport meghatározására van szükség ahhoz, hogy kiválaszthatóak legyenek azok a betegek, akiknél a tervezett ellenőrző endoszkópia stratégiája hasznosnak bizonyulhat.
Célkitűzés:
A tervezett ellenőrző endoszkópiák klinikai hasznát kívántuk felmérni akut gastroduodenalis fekélyvérző betegeink klinikai és endoszkópos adatainak retrospektív elemzésével.
Módszer:
Összesen 274 fekélyvérző beteg adatait elemeztük. A tervezett ellenőrző endoszkópiák hatékonyságának lemérésére az újbóli endoszkópos vérzéscsillapító beavatkozások szükségességét használtuk fel. A betegeket a sürgősségi endoszkópia során észlelt Forrest szerinti fekélystádium alapján csoportosítottuk.
Eredmények:
Az aktívan vérző fekélybetegek (Forrest Ia, Ib) csoportjában a tervezett endoszkópiák alkalmával 23,8%-ban végeztünk újbóli endoszkópos vérzéscsillapítást. Az ércsonkos fekélyesek (Forrest IIa) csoportjában 13,0%-ban, míg a thrombussal fedett fekélyesek (Forrest IIb) körében 13,3%-ban volt szükség újabb endoszkópos hemosztatikus kezelésre az ellenőrző endoszkópiák kapcsán. Bár a beavatkozások gyakorisága közötti különbségek statisztikailag nem szignifikánsak, mégis klinikailag számottevőnek tartható az, hogy az eredetileg aktívan vérző betegek negyedében hasznos volt a tervezett ellenőrző endoszkópia.
Következtetés:
Az eredmények arra engednek következtetni, hogy a tervezett ellenőrző endoszkópia stratégiája a kezdetben aktívan vérző és nagy újravérzési kockázatú betegek számára kedvezőbb kórlefolyást ígér.
Resection of the Primary Colorectal Cancer Is Not Necessary in Nonobstructed Patients with Metastatic Disease
Authors: Damjanov Nevena , Weiss Jared , Haller Daniel G.
Published: October 2009

Asymptomatic patients with metastatic colorectal cancer do not routinely need to undergo resection of the primary tumor. Although several retrospective analyses suggest that patients who undergo resection of the primary tumor live longer, most of these reviewed data prior to the advent of modern polychemotherapy and are subject to considerable bias, as patients who were considered able to undergo surgery likely had better overall prognoses than those who were not. In addition to significant prolongation of overall survival, current combinations of systemic chemotherapeutic agents and targeted agents have allowed improved local and distant tumor control, decreasing the likelihood of local tumor-related complications requiring colon resection.
Gorlin's Syndrome: Case Report and Management Protocol
Authors: Rosti R , Irem A , Kayserili H , Yalcin S
Published: October 2009

Gorlin's Syndrome: Case Report and Management Protocol

Gorlin's syndrome (GS) is a rare autosomal, dominant syndrome, characterized by multiple basal cell carcinomas, odontogenic keratocysts, a characteristic facial appearance, skeletal anomalies and malignancies of various organs throughout the body. We describe a 14-year-old girl with GS and propose a management protocol.
48, XXXX, A Rare Aneuploidy
Authors: Kaur A , Pandhi M , Singh J
Published: October 2009

48, XXXX, A Rare Aneuploidy

The 48, XXXX chromosome constitution is a rare aneuploidy which shows some peculiar manifestations in affected females. This first report from India of tetrasomy X with bilateral, typical, complete coloboma of iris, shows the importance of chromosomal investigation and fluorescentin situhybridization (FISH) in females with mental retardation and dysmorphic features.
Trends and Causes of Congenital Anomalies in the Pleven Region, Bulgaria
Authors: Kovacheva K , Simeonova M , Velkova A
Published: October 2009

Trends and Causes of Congenital Anomalies in the Pleven Region, Bulgaria

We describe the secular trend, pattern and causes of congenital anomalies (CAs) in the Pleven region, Bulgaria. The source of the data was the regional population-based registry of CAs using criteria according to EUROCAT recommendations. During the period 1988-2006, 47,622 births were surveyed. A total of 1,225 cases of CAs were ascertained, giving a total prevalence of 25.72 [95% confidence interval (95% CI) 24.3 to 27.15 per 1,000 births. There was a significant increase in total prevalence from 17.76 per 1,000 births in 1988 to 29.40 in 2006 (χ2 test for trend = 5.03;p= 0.025). Congenital heart disease (4.3 per 1,000 registered births), nervous system anomalies (3.3 per 1,000 births), limb defects (2.5 per 1,000 births) and neural tube defects (2.0 per 1,000 births) demonstrated the highest prevalence. There was a significant upward trend in the prevalence of some specific anomalies: digestive system, tumors, gastroschisis and non syndromal dysmorphologic conditions. Genetic causes were identified in approximately 62% of all cases with CAs (chromosomal 8%, single gene defects 14%, multifactorial 40%). The secular trend and particular pattern of CAs in the Pleven region require some potential underlying contributing factors to be considered: case ascertainment and diagnostic methods, and some environmental factors. These data draw attention to the need of further regional epidemiological studies. The high proportion of genetic causes emphasize the role of genetic services as an integral part of preventive medical care.
Cytogenetic Study on Workmen Occupationally Exposed to Pesticides
Authors: Yi Omari
Published: October 2009

Cytogenetic Study on Workmen Occupationally Exposed to Pesticides

A cytogenetic study was performed on 40 workmen who were exposed to the pesticides malathion and chlorpyrifos and on 30 healthy males who had not been so exposed. The exposed workers had a consistent increase in chromosome abnormalities including chromatid gap, chromatid break, isochromatid break, dicentric and ring chromosomes, as determined by the standard chromosome aberration assay, when compared to the control group. The incidence was significantly higher in exposed smokers than that for exposed non smokers and than that for the unexposed controls as well. These findings provide further evidence for the intrinsic mutagenic activity of the pesticides studied.
Dumbing down or beefing up the curriculum? Integrating an 'academic skills framework' into a first year sociology programme
Authors: Keating Mike , O'Siochru Cathal , Watt Sal
Published: October 2009

This article describes a C-SAP-funded project evaluating the introduction of a new tutorial programme for first year Sociology students, which sought to integrate a 'skills framework' to enable students to develop a range of academic skills alongside their study of the subject.

The pegagogical and institutional background to the decision to adopt this 'integrated' approach is summarised and the staff and student experiences are then evaluated using both quantitative and qualitative methods. Primarily concerned with evaluating staff and student responses to the new programme, this paper also raises some issues with regard to the methodologies of evaluation.
Physiological integration in an introduced, invasive plant increases its spread into experimental communities and modifies their structure
Authors: Yu Fei‐Hai , Wang Ning , Alpert Peter , He Wei‐Ming , Dong Ming
Published: October 2009

What determines the invasiveness of introduced plants is still poorly known. Many of the most invasive plant species are clonal, and physiological integration between connected individuals (ramets) of clonal plants may contribute to their ability to spread into communities and reduce performance of existing species. This contribution of integration to the invasiveness of clonal plants may be greater in denser communities. A greenhouse study was conducted to test these two hypotheses. High‐ and low‐density communities were created by sowing seeds of eight grassland species. Each community was planted with three ramets of the stoloniferous, introduced plant Alternanthera philoxeroides that were disconnected from or left connected to ramets growing on bare soil. Connection increased the spread of Alternanthera within a community, but did not reduce community biomass. Alternanthera grew less in high‐density communities, but connection did not improve its growth more than in low‐density communities. Low‐density communities had higher evenness when Alternanthera was connected than when it was disconnected because shoot mass was lower in the more abundant species in the community and higher in the less abundant ones. These results partly supported the first hypothesis, but not the second. The effect of integration on community structure could be due to higher resource import by the ramets of Alternanthera closer to the dominant species. Integration therefore can increase the initial spread of new clonal plant species into communities and modify the effects of this spread on community structure.
Morphology and development of the gynoecium in Centrolepidaceae: The most remarkable range of variation in Poales
Authors: Sokoloff Dmitry D. , Remizowa Margarita V. , Linder H. Peter , Rudall Paula J.
Published: October 2009

This paper explores the relative impacts of reduction and polymerization on the evolution of reproductive structures in the small but morphologically diverse family Centrolepidaceae. Centrolepidaceae are closely related to Restionaceae and belong to the large order Poales, which also includes the grasses. In the largest genus of Centrolepidaceae, Centrolepis, the reproductive structures are viewed either as highly unusual aggregations of reduced flowers (the pseudanthial interpretation) or as unique flowers evolved through extreme reduction in the androecium, usually accompanied by a drastic increase in carpel number and elaboration of the entire gynoecium. Comparative data are here presented on gynoecia of all three genera of Centrolepidaceae; these data strongly support the latter (euanthial) interpretation. The combined phenomenon of carpel multiplication and decrease in stamen number is unexpected in a predominantly wind‐pollinated lineage. Applying a pseudanthial interpretation would create a considerable morphological gap with reproductive structures of other Poales, whereas accepting a euanthial concept allows an almost continuous morphological series with related taxa.
Charge Transfer Excitons in Polymer/Fullerene Blends: The Role of Morphology and Polymer Chain Conformation
Authors: Hallermann Markus , Kriegel Ilka , Da Como Enrico , Berger Josef M. , von Hauff Elizabeth , Feldmann Jochen
Published: October 2009

Here, it is shown how carrier recombination through charge transfer excitons between conjugated polymers and fullerene molecules is mainly controlled by the intrachain conformation of the polymer, and to a limited extent by the mesoscopic morphology of the blend. This experimental result is obtained by combining near‐infrared photoluminescence spectroscopy and transmission electron microscopy, which are sensitive to charge transfer exciton emission and morphology, respectively. The photoluminescence intensity of the charge transfer exciton is correlated to the degree of intrachain order of the polymer, highlighting an important aspect for understanding and limiting carrier recombination in organic photovoltaics.
Relapsed or refractory nongastric marginal zone B‐cell lymphoma: Multicenter retrospective analysis of 92 cases
Authors: Oh Sung Yong , Kim Won Seog , Kim Seok Jin , Kim Jin Seok , Kim Sung‐Hyun , Lee Dae Ho , Won Jong‐Ho , Hwang In Gyu , Kim Min Kyoung , Lee Soon Il , Kim Jong Gwang , Yang Deok‐Hwan , Kang Hye Jin , Choi Chul Won , Park Jinny , Choi Young Jin , Kim Hyo Jung , Kwon Jung Hye , Suh Cheolwon , Kim Hyo‐Jin
Published: October 2009

Over its long survival duration, marginal zone B‐cell lymphoma (MZL) routinely involves frequent relapses. In this study, we conducted a retrospective analysis to identify the clinical features and outcomes of relapsed or refractory MZL. From 1995 to 2008, a total of 92 patients with relapsed MZL were retrospectively analyzed. The median age of our subjects was 53.5 years (range: 23–82 years). The most common primary sites of involvement were the orbit and ocular adnexa (28.3%) followed by the lymph node and lymphatic organs (23.9%), and multiple mucosa‐associated lymphoid tissue (MALT) sites (13.0%). The median time to relapse from initial diagnosis was 25.5 months. Of the 53 patients with Stage I or II at diagnosis, 42 patients (79.2%) evidenced locoregional recurrence. Among these locoregional relapsed patients, 27 patients achieved CR (54.1%) or PR (18.9%). In addition to the 39 patients initially in advanced Stage III or IV, a total of 50 patients were in advanced stage at relapse. Among those patients with advanced stage at relapse, 44 patients were treated. The overall response rate was 54.5% (24 patients), with 18 CRs and 6 PRs. The median time to progression (TTP) was 34.1 months (95% CI: 11.3–56.9 months) and the estimated 5‐year overall survival (OS) was 84.3%. The majority of them was controlled well with salvage treatment, and could achieve prolonged survival. However, patients' refractory to initial therapy and advanced relapse evidenced shorter TTP and OS. Thus, we need to consider more aggressive treatment in cases of refractory MZL or advanced relapsed MZL. Am. J. Hematol., 2009. © 2009 Wiley‐Liss, Inc.
A convenient synthesis of nanocrystalline chalcopyrite, CuFeS2 using single‐source precursors
Authors: Disale Sujit D. , Garje Shivram S.
Published: October 2009

Nanocrystalline chalcopyrite (CuFeS2) have been synthesized using single‐source precursors, CuL2 and Cu(LH)2Cl2 (where LH = monoacetylferrocene thiosemicarbazone) by pyrolysis and solvothermal decomposition methods. The nanocrystals were characterized by UV–visible spectroscopy, X‐ray powder diffraction, transmission electron microscopy and energy dispersive X‐ray analysis. The magnetic character was determined by the hysteresis loop. CuFeS2 nanocrystallites prepared by the pyrolysis of CuL2 and Cu(LH)2Cl2 have a cubic phase and rod‐like morphology with diameters of about 18 and 15 nm, respectively, and lengths of about 195–390 and 100–145 nm, respectively. However, CuFeS2 nanoparticles obtained by solvothermal route from CuL2 and Cu(LH)2Cl2, which are capped with ethylene glycol, possess a nearly spherical shape with an average grain size of 16 and 11 nm, respectively. Copyright © 2009 John Wiley & Sons, Ltd.
Risk Factor Adjustment in Marginal Structural Model Estimation of Optimal Treatment Regimes
Authors: Moodie Erica E. M.
Published: October 2009

Marginal structural models (MSMs) are an increasingly popular tool, particularly in epidemiological applications, to handle the problem of time‐varying confounding by intermediate variables when studying the effect of sequences of exposures. Considerable attention has been devoted to the optimal choice of treatment model for propensity score‐based methods and, more recently, to variable selection in the treatment model for inverse weighting in MSMs. However, little attention has been paid to the modeling of the outcome of interest, particularly with respect to the best use of purely predictive, non‐confounding variables in MSMs. Four modeling approaches are investigated in the context of both static treatment sequences and optimal dynamic treatment rules with the goal of estimating a marginal effect with the least error, both in terms of bias and variability.
Mixtures of hemoglobin‐based oxygen carriers and perfluorocarbons exhibit a synergistic effect in oxygenating hepatic hollow fiber bioreactors
Authors: Chen Guo , Palmer Andre F.
Published: October 2009

Hepatic hollow fiber (HF) bioreactors are being developed for use as bioartificial liver assist devices (BLADs). In general, BLADs suffer from O2 limited transport, which reduces their performance. This modeling study seeks to investigate if O2 carrying solutions consisting of mixtures of hemoglobin‐based oxygen carriers (HBOCs) and perfluorocarbons (PFCs) can enhance O2 transport to hepatocytes cultured in the extra capillary space (ECS) of HF bioreactors. We simulated supplementing the circulating cell culture media stream of the HF bioreactor with a mixture containing these two types of oxygen carriers (HBOCs and PFCs). A mathematical model was developed based on the dimensions and physical characteristics of a commercial HF bioreactor. The resulting set of partial differential equations, which describes fluid transport; as well as, mass transport of dissolved O2 in the pseudo‐homogeneous PFC/water phase and oxygenated HBOC, was solved to yield the O2 concentration field in the three HF domains (lumen, membrane and ECS). Our results show that mixtures of HBOC and PFC display a synergistic effect in oxygenating the ECS. Therefore, the presence of both HBOC and PFC in the circulating cell culture media dramatically improves transport of O2 to cultured hepatocytes. Moreover, the in vivo O2 spectrum in a liver sinusoid can be recapitulated by supplementing the HF bioreactor with a mixture of HBOCs and PFCs at an inlet pO2 of 80 mmHg. Therefore, we expect that PFC‐based oxygen carriers will be more efficient at transporting O2 at higher O2 levels (e.g., at an inlet pO2 of 760 mmHg, which corresponds to pure O2 in equilibrium with aqueous cell culture media at 1 atm). Biotechnol. Bioeng. 2010; 105: 534–542. © 2009 Wiley Periodicals, Inc.
Micro determination of cortisol and cortisone in umbilical cord blood by chemiluminescent high‐performance liquid chromatography
Authors: Hasegawa Takeshi , Kubo Hiroaki , Shinozaki Koichi , Nowatari Masahiko , Ishii Masahiro
Published: October 2009

A simple, sensitive and specific chemiluminescent high‐performance liquid chromatography method, based on the luminol reaction, for determination of serum cortisol and cortisone, was established. In infants, placental 11β‐hydroxysteroid dehydrogenase type 2 enzyme (11β‐HSD2) activity may affect adrenal function early after birth. The cortisol–cortisone ratio of serum concentrations in umbilical cord blood is an indicator of placental 11β‐HSD2 activity. The optimum conditions for the luminol reaction were determined to be 1.5 mM luminol, 0.6 M sodium hydroxide, 0.15 mm potassium hexacyanoferrate(III) and 200 mM potassium hexacyanoferrate (II). The calibration curves for cortisol and cortisone exhibited good linearity. The correlation coefficients of the calibration curves were 0.996. The intra‐ and inter‐day precisions were in the ranges: cortisol 7.0–12.2 and 4.4–9.2%, cortisone 5.3–7.0 and 6.2–9.9%. The recoveries of these steroids were in the ranges: cortisol 97–105%, cortisone 94–102%. The limits of detection were as follows: cortisol, 0.17 μg/dl; cortisone 0.15 μg/dl. This assay could be successfully applied to determination of the cortisol–cortiosone ratio of serum concentrations in umbilical cord bloods. Copyright © 2009 John Wiley & Sons, Ltd.
Determination of kynurenic acid levels in rat brain microdialysis samples and changes in kynurenic acid levels induced by N‐acetylaspartic acid
Authors: Tomiya Masayuki , Fukushima Takeshi , Ogaya Tadahiro , Sone Yukiko , Mitsuhashi Shogo , Toyo'oka Toshimasa
Published: October 2009

The levels of kynurenic acid, an endogenous antagonist of α7 nicotinic acetylcholine and N‐methyl‐D‐aspartate receptors, were measured in microdialysis samples obtained from the prefrontal cortices of rats using column‐switching high‐performance liquid chromatography with fluorescence detection. When the perfusate was constantly infused at a rate of 1.0 μ/min, the in vitro recovery of kynurenic acid through the dialysis membrane was approximately 20.4%, and the precision was within 1.31%. Endogenous kynurenic acid in the microdialysis sample was clearly detected using column‐switching high‐performance liquid chromatography. As an application study, N‐acetyl‐L‐aspartic acid, an endogenous metabolite and precursor of N‐acetyl‐L‐aspartyl‐L‐glutamic acid, which is an agonist of metabotropic glutamate receptors, was infused for 120 min through the microdialysis probe. The kynurenic acid level significantly increased during the infusion of N‐acetyl‐L‐aspartic acid, suggesting that kynurenic acid might have some association with N‐acetyl‐L‐aspartic acid in vivo. Copyright © 2009 John Wiley & Sons, Ltd.
Development and validation of RP‐HPLC‐fluorescence method for quantitative determination of quinidine, a probe substrate for P‐glycoprotein inhibition assay using Caco‐2 cell monolayer
Authors: Patil Anand G. , Reddy Dilip , D'Souza Russell , Damre Anagha
Published: October 2009

A simple, sensitive and specific reverse‐phase high‐performance liquid chromatographic (RP‐HPLC) method with fluorescence detection was developed for quantitation of quinidine from HBSS buffer. The method was applicable in the bi‐directional transport assay for evaluation of the inhibitory effect of test compounds on P‐glycoprotein‐mediated quinidine transport; quinidine was used as a probe P‐glycoprotein substrate. The calibration curve was linear (correlation coefficient ≥99) in the range 0.30–100.00 nm. The method was validated and is specific and sensitive with limit of quantitation of 300 pm for quinidine. The method was found to be accurate and precise in the working calibration range. Stability studies were carried out at different storage conditions where the analyte was found to be stable. The applicability and reliability of the analytical method was evaluated by successful demonstration of efflux ratio (PappB → A/PappA → B) in the Caco‐2 cell monolayer efflux assay. The efflux ratio for quinidine (100 nm) alone was 10.8, which reduced to less than 2 in the presence of the classical P‐gp inhibitors verapamil and ketoconazole (100 μm each). Copyright © 2009 John Wiley & Sons, Ltd.
Sensitive LC‐MS‐MS method for the determination of tiopronin in human plasma
Authors: Jiang Bo , Xu Yu , Xu Fang , Sun Junjie , Li Na , Luo Yanan , Guo Qingxiang
Published: October 2009

A highly selective and sensitive LC‐MS‐MS method was developed and validated to quantify tiopronin in human plasma, using fudosteine as the internal standard (IS). L‐Cysteine and 1,4‐dithiothreitol (DTT) were used as the reducer and the stabilizer to release and stabilify tiopronin from a dimmer and mix forms with endogenous thiols in the treatment of plasma samples. After a simple liquid–liquid extraction with ethyl acetate in acidic condition, the post‐treatment samples were analyzed on a C18 column interfaced with a triple‐quadruple tandem mass spectrometer using negative electrospray ionization. Methanol and water (40:60, v/v) were used as the isocratic mobile phase, with 0.2% formic acid and 1.0 mM tris (hydroxymethyl) aminomethane (Tris) in water. The method was validated to demonstrate the specificity, lower limit of quantification, accuracy and precision of measurements. The assay was linear over the concentration range 0.078–10 μg/mL. The correlation coefficients for the calibration curves ranged from 0.9980 to 0.9990. The intra‐ and inter‐day precisions, calculated from quality control samples, were not more than 10.49%. The method was employed in a pharmacokinetic study after oral administration of 200 mg tiopronin tablets to 24 healthy volunteers. Copyright © 2009 John Wiley & Sons, Ltd
The OstialPro positioning system for a renal artery stenosis
Authors: Igbokidi Oyidie , Jovin Ion S.
Published: October 2009

Aorto‐ostial lesions pose complex technical challenges in percutaneous revascularization procedures. The successful use of the ostial positioning system OstialPro has been reported in coronary arteries. This nitinol device has self expanding legs that open just distal to the guide catheter. This allows the stent to be deployed in the ostium of the vessel with the guide catheter positioned in the aorta and allows for accurate anatomic visualization of the plane between the ostium and the aorta. Besides coronary interventions, the OstialPro could be useful in peripheral vascular interventions for ostial renal, mesenteric or vertebral arteries stenoses. We report the case of a patient with a significant ostial renal artery stenosis who underwent a successful percutaneous intervention using the OstialPro device. © 2009 Wiley‐Liss, Inc.
Selected Examples of High‐Pressure Reactions in Glass Microreactors
Authors: Verboom W.
Published: October 2009

Recent examples of high‐pressure organic reactions in (flow) glass microreactors of micrometer dimensions are described. Different types of reactions such as Diels‐Alder and nucleophilic aromatic substitution reactions performed in a capillary microreactor gave rate enhancements of 1.5–2.7 at 600 bar. Specifically designed flow glass microreactors, that withstand pressures of 140–690 bar, were used to study Diels‐Alder and oxidation reactions. The use of supercritical fluids gives rise to considerable rate enhancements, while the use of a transparent microreactor allows to visualize phase transitions.
An Adaptor Domain‐Mediated Autocatalytic Interfacial Kinase Reaction
Authors: Liao Xiaoli , Su Jing , Mrksich Milan
Published: October 2009

This paper describes a model system for studying the autocatalytic phosphorylation of an immobilized substrate by a kinase enzyme. This work uses self‐assembled monolayers (SAMs) of alkanethiolates on gold to present the peptide substrate on a planar surface. Treatment of the monolayer with Abl kinase results in phosphorylation of the substrate. The phosphorylated peptide then serves as a ligand for the SH2 adaptor domain of the kinase and thereby directs the kinase activity to nearby peptide substrates. This directed reaction is intramolecular and proceeds with a faster rate than does the initial, intermolecular reaction, making this an autocatalytic process. The kinetic non‐linearity gives rise to properties that have no counterpart in the corresponding homogeneous phase reaction: in one example, the rate for phosphorylation of a mixture of two peptides is faster than the sum of the rates for phosphorylation of each peptide when presented alone. This work highlights the use of an adaptor domain in modulating the activity of a kinase enzyme for an immobilized substrate and offers a new approach for studying biochemical reactions in spatially inhomogeneous settings.