bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐resolution NMR studies of the zinc‐binding site of the Alzheimer's amyloid β‐peptide
Authors: Danielsson Jens , Pierattelli Roberta , Banci Lucia , Gräslund Astrid
Published: November 2006

Metal binding to the amyloid β‐peptide is suggested to be involved in the pathogenesis of Alzheimer's disease. We used high‐resolution NMR to study zinc binding to amyloid β‐peptide 1–40 at physiologic pH. Metal binding induces a structural change in the peptide, which is in chemical exchange on an intermediate rate, between the apo‐form and the holo‐form, with respect to the NMR timescale. This causes loss of NMR signals in the resonances affected by the binding. Heteronuclear correlation experiments, 15N‐relaxation and amide proton exchange experiments on amyloid β‐peptide 1–40 revealed that zinc binding involves the three histidines (residues 6, 13 and 14) and the N‐terminus, similar to a previously proposed copper‐binding site [Syme CD, Nadal RC, Rigby SE, Viles JH (2004) J Biol Chem279, 18169–18177]. Fluorescence experiments show that zinc shares a common binding site with copper and that the metals have similar affinities for amyloid β‐peptide. The dissociation constant Kd of zinc for the fragment amyloid β‐peptide 1–28 was measured by fluorescence, using competitive binding studies, and that for amyloid β‐peptide 1–40 was measured by NMR. Both methods gave Kd values in the micromolar range at pH 7.2 and 286 K. Zinc also has a second, weaker binding site involving residues between 23 and 28. At high metal ion concentrations, the metal‐induced aggregation should mainly have an electrostatic origin from decreased repulsion between peptides. At low metal ion concentrations, on the other hand, the metal‐induced structure of the peptide counteracts aggregation.
Reducing Engine Idle Speed Deviations Using the Internal Model Principle
Authors: Osburn Andrew W. , Franchek Matthew A.
Published: November 2006

Presented in this paper is a multivariable linear feedback controller design methodology for idle speed control of spark-ignition engines. The engine is modeled as a multi-input, single-output system. The proposed feedback control system employs both throttle and ignition timing to control engine speed and engine roughness. Throttle is used to attenuate low frequency components of the speed error and reject mean speed errors. Spark advance is used to reduce cylinder-to-cylinder differences in torque production by limiting high frequency speed deviations. The algorithm is executed in the crank-angle domain, and the internal model principle serves as the basis for cylinder torque balancing. The nonlinear relationship between ignition timing and torque production is explicitly incorporated into the design process using a sector bound. A loop shaping approach is proposed to design the feedback controller, and absolute stability of the nonlinear closed-loop system is guaranteed through the Tsypkin Criterion. Experimental results from implementation on a Ford 4.6L V-8 engine are provided.
Recoil Experiments Using a Compressed Air Cannon
Authors: Taylor Brett
Published: November 2006

Ping-Pong vacuum cannons, potato guns, and compressed air cannons are popular and dramatic demonstrations for lecture and lab.1–3 Students enjoy them for the spectacle, but they can also be used effectively to teach physics. Recently we have used a student-built compressed air cannon as a laboratory activity to investigate impulse, conservation of momentum, and kinematics. It is possible to use the cannon, along with the output from an electronic force plate, as the basis for many other experiments in the laboratory. In this paper, we will discuss the recoil experiment done by our students in the lab and also mention a few other possibilities that this apparatus could be used for.
A Simple Laser Microphone for Classroom Demonstration
Authors: Moses James M. , Trout K. P.
Published: November 2006

Communication through the modulation of electromagnetic radiation has become a foundational technique in modern technology. In this paper we discuss a modern day method of eavesdropping based upon the modulation of laser light reflected from a window pane. A simple and affordable classroom demonstration of a “laser microphone” is described.
Sensitivity of the Atlantic Thermohaline Circulation and Its Stability to Basin-Scale Variations in Vertical Mixing
Authors: Sijp Willem P. , England Matthew H.
Published: November 2006

This study shows that a reduction in vertical mixing applied inside the Atlantic basin can drastically increase North Atlantic Deep Water (NADW) stability with respect to freshwater perturbations applied to the North Atlantic. This is contrary to the notion that the stability of the ocean’s thermohaline circulation simply scales with vertical mixing rates. An Antarctic Intermediate Water (AAIW) reverse cell, reliant upon upwelling of cold AAIW into the Atlantic thermocline, is found to be associated with stable states where NADW is collapsed. Transitions between NADW “on” and “off” states are characterized by interhemispheric competition between this AAIW cell and the NADW cell. In contrast to the AAIW reverse cell, NADW eventually upwells outside the Atlantic basin and is thus not as sensitive to changes in vertical mixing within the Atlantic. A reduction in vertical mixing in the Atlantic weakens the AAIW reverse cell, resulting in an enhanced stability of NADW formation. The results also suggest that the AAIW reverse cell is responsible for the stability of NADW collapsed states, and thereby plays a key role in maintaining multiple equilibria in the climate system. A global increase of vertical mixing in the model results in significantly enhanced NADW stability, as found in previous studies. However, an enhancement of vertical mixing applied only inside the Atlantic Ocean results in a reduction of NADW stability. It is concluded that the stability of NADW formation to freshwater perturbations depends critically on the basin-scale distribution of vertical mixing in the world’s oceans.
Physical Processes Associated with the Tropical Atlantic SST Meridional Gradient
Authors: Hu Zeng-Zhen , Huang Bohua
Published: November 2006

The major modes of seasonal sea surface temperature (SST) meridional gradient and their connection with some regional mean SST indices in the Atlantic Ocean are examined using reanalysis data. The focus of the work is on the evolution of the dominant mode of the meridional SST gradient in boreal spring and the associated physical processes. The spatial distribution of the dominant mode in boreal spring is a seesaw pattern, reflecting the opposite variation of the meridional SST gradient between the subtropical and tropical North Atlantic, which resulted from a coherent warming or cooling with maxima along 10°–15°N. It is confirmed that this mode is dominated by the wind–evaporation–SST feedback. The feedback persists a longer time in the western Atlantic than in the eastern. The contribution to the SST variation is mainly from latent heat flux. The surface longwave and shortwave cloud radiative forcings are mainly determined by low cloud cover variations. The authors also found that the thermodynamic mode that peaked in boreal spring becomes weak in the following boreal summer. A similar thermodynamic mode appears in a northward position in boreal autumn, and its life cycle is shorter than the one in boreal spring.

In contrast to the leading mode in boreal spring, it is shown that the leading mode in boreal summer is a dynamical air–sea feedback mode, reflecting a coherent warming or cooling pattern extending from the Angolan coast toward the equator in the Gulf of Guinea. The thermodynamic processes act as a negative feedback. The net surface latent heat flux anomalies are the leading damping factor, while the sensible heat flux plays the same role on a smaller scale.
Interannual Variation of the Tropical Cyclone Activity over the Western North Pacific
Authors: Chen Tsing-Chang , Wang Shih-Yu , Yen Ming-Cheng
Published: November 2006

An effort was made to search for relationships between interannual variations of population, lifetime, genesis locations, and intensity of named typhoons and numbered tropical depressions in the western North Pacific during the 1979–2002 period. To support this research task, climatological relationships of tropical cyclone characteristics were also investigated for these cyclones. Major findings of this study are summarized as follows:Climatology: Measured by the intensity scale of the Japan Meteorological Agency, three groups of tropical cyclones were identified in terms of population versus intensity: Group 1 [tropical depression (TD) + typhoon (TY)], Group 2 (strong + very strong TY), and Group 3 (catastrophic TY). This group division coincides with that formed in terms of lifetime of tropical cyclones versus intensity. Weak cyclones (Group 1) have a larger population than strong cyclones (Group 3), while the former group has shorter lifetime than the latter group. For genesis locations, the monsoon trough is established as a favorable region of tropical cyclone genesis because it provides an environment of large vorticity. Therefore, the northward latitudinal displacement of the maximum genesis frequency in the three groups of tropical cyclones follows that of the monsoon trough.Interannual variation: Any mechanism that can modulate the location and intensity of the monsoon trough affects the genesis location and frequency of tropical cyclones. In response to tropical Pacific sea surface temperature anomalies, a short wave train consisting of east–west oriented cells emanates from the Tropics and progresses along the western North Pacific rim. Population of the Group-1 tropical cyclones varies interannually in phase with the oscillation of the anomalous circulation cell northeast of Taiwan and south of Japan in this short wave train, while that of Group 3 fluctuates coherently with the tropical cell of this short wave train. Because these two anomalous circulation cells exhibit opposite polarity, the out-of-phase interannual oscillation between these two cells results in the opposite interannual variation of genesis frequency between tropical cyclones of Groups 1 and 3.
Dry Bias in Satellite-Derived Clear-Sky Water Vapor and Its Contribution to Longwave Cloud Radiative Forcing
Authors: Sohn Byung-Ju , Schmetz Johannes , Stuhlmann Rolf , Lee Joo-Young
Published: November 2006

In this paper, the amount of satellite-derived longwave cloud radiative forcing (CRF) that is due to an increase in upper-tropospheric water vapor associated with the evolution from clear-sky to the observed all-sky conditions is assessed. This is important because the satellite-derived clear-sky outgoing radiative fluxes needed for the CRF determination are from cloud-free areas away from the cloudy regions in order to avoid cloud contamination of the clear-sky fluxes. However, avoidance of cloud contamination implies a sampling problem as the clear-sky fluxes represent an area drier than the hypothetical clear-sky humidity in cloudy regions. While this issue has been recognized in earlier works this study makes an attempt to quantitatively estimate the bias in the clear-sky longwave CRF. Water vapor amounts in the 200–500-mb layer corresponding to all-sky condition are derived from microwave measurements with the Special Sensor Microwave Temperature-2 Profiler and are used in combination with cloud data for determining the clear-sky water vapor distribution of that layer. The obtained water vapor information is then used to constrain the humidity profiles for calculating clear-sky longwave fluxes at the top of the atmosphere. It is shown that the clear-sky moisture bias in the upper troposphere can be up to 40%–50% drier over convectively active regions. Results indicate that up to 12 W m−2 corresponding to about 15% of the satellite-derived longwave CRF in tropical regions can be attributed to the water vapor changes associated with cloud development.
Robust Responses of the Hydrological Cycle to Global Warming
Authors: Held Isaac M. , Soden Brian J.
Published: November 2006

Using the climate change experiments generated for the Fourth Assessment of the Intergovernmental Panel on Climate Change, this study examines some aspects of the changes in the hydrological cycle that are robust across the models. These responses include the decrease in convective mass fluxes, the increase in horizontal moisture transport, the associated enhancement of the pattern of evaporation minus precipitation and its temporal variance, and the decrease in the horizontal sensible heat transport in the extratropics. A surprising finding is that a robust decrease in extratropical sensible heat transport is found only in the equilibrium climate response, as estimated in slab ocean responses to the doubling of CO2, and not in transient climate change scenarios. All of these robust responses are consequences of the increase in lower-tropospheric water vapor.
Effect of saturating cation on tactoid size distribution in bentonite suspensions
Authors: Whalley W. R. , Mullins C. E.
Published: November 2006

Centrifugal photosedimentation was used to determine the size distribution of dilute bentonite suspensions as a function of saturating cation. This method is shown to give a better estimate of the effect of saturating cation on tactoid size than the techniques that are currently used. The results indicate that tactoids may occur in preferred size ranges.
Acrylonitrile-smectite complexes
Authors: Bergaya F. , Kooli F.
Published: November 2006

The adsorption of acrylonitrile (AN) monomer vapour in the interlamellar space of smectites exchanged with different cations (Na or Y or hexylammonium) was monitored and used to yield macromolecular layers. Polymerization in the presence or absence of a free-radical initiator was obtained by heating at 100°C for 72 h. Cyclization can already be obtained at this stage, and is completed by heating the polyacrylonitrile (PAN)-complexes at 220°C for 48 h.
Ordering of illite-smectite in Upper Jurassic Claystones from the North Sea
Authors: Lindgreen H. , Hansen P. L.
Published: November 2006

Upper Jurassic claystones of Kimmeridgian-Volgian(-Ryazanian) age are the main source rocks for oil in the Central Trough, North Sea. Drill cuttings and cores from the depth interval 2368–4548 m, the interval from early-mature to peak oil generation, have been investigated by high-resolution transmission electron microscopy (HRTEM) of ion-milled rock samples, and by HRTEM and powder X-ray diffraction (XRD) of dispersed illite-smectite (I-S) mixed-layers isolated from the <0·2µm fraction. Ordering parameters were determined by XRD profile simulation. TEM on shadowed particles, combined with XRD evidence, showed that dispersed I-S consists of a mixture of 10–70 Å thick particles, whereas HRTEM showed that intact bulk rock was dominated by 50–200 Å thick particles. Disruption, possibly along smectite planes, of the larger particles in the bulk rock formed the thin particles in dispersed I-S. HRTEM showed 20 and 30 Å periodic enhancement in the contrast of lattice fringes in bulk rock samples as well as in dispersed I-S crystals. These features were interpreted as ordered I-S crystals. Indications of disintegration of larger I-S particles during sample dispersion and of the presence of ordered I-S crystals in the intact bulk rock support the layer transformation mechanism for the conversion of smectite to illite.
Origin of clay minerals in the Bonarelli Horizon (Umbrian Apennines, central Italy)
Authors: Brigatti M. F. , Poppi L.
Published: November 2006

Chemical, thermal, X-ray and statistical analyses were carried out on the clay fraction of the Bonarelli Horizon (Umbrian region, Central Italy) in order to investigate its origin. The vertical lithological sequence (organic carbon, siliceous and clay layers of varying colour and thickness) seems to change regularly, allowing the horizon to be subdivided into five sub-horizons (A to E). Sub-horizon B is clearly distinguishable from the others on the basis of the clay fractions. The presence of organic material and authigenic sulphates, constant chemical composition within a single sub-horizon, and regular repetition of the layers, show that the Bonarelli Horizon is the result of an alternation of anoxic events in a continental margin facies. A substantial contribution of volcanoclastic material is suggested for sub-horizon B.
Evidence of Ostwald ripening related recrystallization of diagenetic chlorites from reservoir rocks offshore Norway
Authors: Jahren J. S.
Published: November 2006

Chemical variations in individual chlorite crystals of diagenetic origin delineated by energy dispersive X-ray spectroscopy (EDS) in a transmission electron microscope (TEM) indicate a temperature dependent chemical zonation in each grain. Silicon decreases and Al increases with higher temperature resulting in a decreasing Si/Al ratio away from the crystal core reflecting the time and rate of the crystal growth. Chlorite particle-size distributions obtained by scanning electron microscopy (SEM) give steady state profiles which suggests that the chlorite growth is controlled by a grain coarsening process related to Ostwald ripening.
Illitization and organic maturity in Silurian sediments from the Southern Uplands of Scotland
Authors: Pearce R. B. , Clayton T. , Kemp A. E. S.
Published: November 2006

Discrepancies between clay mineral and organic indicators of very low-grade metamorphism have been observed from the Southern Uplands of Scotland. In the Southern Belt, I-S expandability ranges from 18–5% and chitinozoan reflectance from 0·8–2·1% R0 mean; a clear correlation exists between I-S expandability and organic maturity. At Dob's Linn in the Central Belt, I-S expandabilities range from 18–10%, and chitinozoan reflectance from 3·6–4·8% R0 mean. The results from Dob's Linn show anomalously high I-S expandabilities with respect to maturity, both in comparison with the Southern Belt and with previous work from other regions. K-feldspar is present in variable amounts in the Southern Belt, but is not detectable by XRD at Dob's Linn. Low K+ activity is believed to have resulted in a slower reaction rate at Dob's Linn, and a consequent “lag” in I-S expandability with respect to the Southern Belt.
A potassium-rich beidellite from a laterite pallid zone in Western Australia
Authors: Singh Balwant , Gilkes R. J.
Published: November 2006

A smectite formed by weathering of mica in a laterite pallid zone at Boddington, Western Australia has been investigated by analytical electron microscopy. The evidence suggests that this mineral has the chemical composition and swelling properties of ideal beidellite but is anomalous in containing abundant non-exchangeable K. This K balances half of the layer charge that arises mostly from tetrahedral substitution of Al3+for Si4+, with the K+occupying one sixth of the sites occupied by K in mica.
Mechanisms of interaction between montmorillonite and 3-aminotriazole
Authors: Morillo E. , Pérez-Rodríguez J. L. , Maqueda C.
Published: November 2006

The adsorption of aminotriazole, at its solution pH, with montmorillonite saturated with different cations has been studied. A pesticide-montmorillonite complex is formed through interlamellar cations which are not displaced. Aminotriazole is situated mostly as a polarized molecule around Mg2+ and Zn2+ cations, removing a great amount of water. In Na+- and Li+-montmorillonite, the pesticide remains as a non-polarized molecule, hydration water being retained in the interlamellar space; the pesticide is coordinated to interlamellar cations through water bridges. For all samples a proportion of cationic aminotriazole is also adsorbed, the amount being greater with increasing polarizing power of the interlamellar cation; consequently, in Fe3+-montmorillonite all the aminotriazole adsorbed is in the cationic form.
On the genesis and composition of natural pyroaurite
Authors: Taylor R. M. , Hansen H. C. B. , Stanger G. , Bender Koch C.
Published: November 2006

Samples of the mineral pyroaurite, formed from the weathering of partially serpentinised harzburgite (olivine + pyroxene) were found in an arid region of the Sultanate of Oman. These were either golden or silver in colour depending on the horizon from which they were derived. Chemical analysis showed that the colour variation was primarily due to the differing conditions in the hydrological environment. The golden colour was attributed to small Fe(III) oxide particles detected by Mössbauer spectroscopy. In addition, the samples were examined by X-ray diffraction, scanning electron microscopy, and glycerol intercalation. These results were compared with a synthetic pyroaurite sample prepared under conditions (previously reported) similar to those in nature. These conditions are shown to approximate to those found in the hydrological environment in the zones of the natural pyroaurite formation.
The use of glycerol intercalates in the exchange of CO32−with SO42−, NO3−or Cl−in pyroaurite-type compounds
Authors: Hansen H. C. B. , Taylor R. M.
Published: November 2006

Strongly held carbonates anions in the interlayer region of pyroaurite-type compounds, [MlII1−xM2IIIx(OH)2]x+[(CO3)x/2yH2O]x−(x= 0·15−0·44), can be relatively easily exchanged by other anions such as NO3−, Cl−or SO42−dissolved in heated glycerol. Some Fe(III) of pyroaurite is reduced to Fe(II) by the glycerol treatment. If pyroaurite is treated with glycerol in the absence of dissolved anions or with glycerol vapour at 120°C, glycerol becomes intercalated in the interlayers. In all examples the interlayer CO32−is partially or completely lost as CO2. In aqueous salt solutions a glycerol intercalated form allows other anions to substitute in the interlayer. Expansion in thec-axis direction following glycerol treatment depends on (1) the method of glycerol treatment, (2) the trivalent metal in the octahedral sheet, and (3) the interlayer anions. Heated glycerol causes a different expansion to that produced by its vapour phase at 120°C. The variation ind(003) follows the series: hydrotalcitevap. > pyroauritevap.> hydrotalciteliquid> pyroauriteliquid> SO42−-pyroauritevap. > SO42−-hydrotalcitevap., where liquid refers to glycerol used at 160–180°C and vap. refers to glycerol vapour at 120°C Carbonate-free, glycerol-intercalated pyroaurite compounds may serve as re-usable anion absorbers. Glycerol intercalates of pyroaurite-type compounds may also be useful to study and identify stacking sequences and interlayer compositions in these minerals.
A mineralogical and geochemical approach to establishing a sedimentary model in a passive continental margin (Subbetic Zone, Betic Cordilleras, SE Spain)
Authors: Ortega-Huertas M. , Palomo I. , Moresi M. , Oddone M.
Published: November 2006

The spatial and vertical distributions of six clay mineral assemblages were identified in the pelagic marls and marly limestones and in the Ammonitico Rosso of the Lower Jurassic in the Betic Cordilleras (SE Spain). The six assemblages contain varying proportions of illite, kaolinite, chlorite, smectite and mixed-layer illite-smectite. The clay mineralogy and the geochemical data, particularly for the rare earth elements, indicate that the sediments were deposited in a pelagic environment influenced by a nearby continent. The source areas were many and lithologically varied. Clay mineralogy and geochemistry are shown to be most useful in the reconstruction of the palaeogeography of a basin in a passive continental margin.
Crystallochemistry, properties and organization of soil clays derived from major sedimentary rocks in France
Authors: Robert M. , Hardy M. , Elsass F.
Published: November 2006

The nature, crystallochemistry, organization and surface properties of soil clays derived from the most representative sedimentary formations of France are described, using qualitative and quantitative mineralogical methods and high resolution transmission microscopy (HRTEM). The main results show that soil clays differ significantly from reference clays. Even when 2:1 phyllosilicates are dominant, the clays always contain multimineral phases. The smectitic component is dioctahedral and of beidellite type. Soil clay organization is specific: all the clay particles have a short lateral extension and few layers (mean 5 layers, and even mono-layers occur). The superposition of such small particles leads to the formation of what are called “texturally interstratified minerals” which are dominant in soil clays. Exchange and surface properties (high ratio of external surface to total surface area), are related to clay organization.
Concentration of iron oxides from soil clays by 5 m NaOH treatment: the complete removal of sodalite and kaolin
Authors: Singh Balwant , Gilkes R. J.
Published: November 2006

The Kämpf & Schwertmann (1982) procedure for concentrating iron oxides in soil clays by dissolution of kaolin and gibbsite by boiling for 1 h in 5 m NaOH may not dissolve all kaolin, and also results in the precipitation of sodalite. For the complete dissolution of kaolin in kaolin-rich soil clays a boiling time of 2 h in 5 m NaOH was required. The large amounts of sodalite produced were not removed by the prescribed single wash in 0·5 m HCl. Oxalate soluble Al contents of iron oxide concentrates were sometimes very high and dithionite Fe contents were very low both in concentrates containing sodalite, and in those for which sodalite was not detected by XRD, but where a previously unsuspected amorphous sodalite-like phase may have been present. Complete removal of precipitated sodalite was achieved by two extractions with 0·5 m HCl at 25°C for 20 min. This modified procedure does not alter the Al-substitution and crystal size of goethite, hematite and maghemite as determined by XRD measurements.
Thermogravimetric study of the desorption of cyclohexylamine and pyridine from an acid-treated Wyoming bentonite
Authors: Breen C.
Published: November 2006

Four 15 g samples of an unsedimented Wyoming bentonite were treated with 200 cm3 of 0·025, 0·050, 0·100 and 0·250 mol dm−3 H2SO4 for 1 h at room temperature (samples I–IV, respectively). Three further 15 g samples were treated with 200 cm3 of 50% (v/v) H2SO4 for 1 h at 20°C (sample V), and 1 and 2 h under reflux (samples VI and VII, respectively). X-ray fluorescence and diffraction studies revealed that only samples VI and VII suffered any substantial structural attack. The resulting acidity of the clays, determined by cyclohexylamine desorption, indicated that sample V contained the largest number of protons at 0·59 mmol H+ (g clay)−1. Sample V was also the most efficient catalyst for the dehydration and etherification of hexan-1-ol, giving a combined product yield of 17·0% after 2 h reflux in neat reactant. The parent bentonite and samples I and II showed no discernible catalytic activity despite measured acidities of 0·1, 0·24 and 0·34 mmol H+ (g clay)−1. In contrast samples III and IV gave combined product yields of 4·5 and 11·0%, respectively, which correlated well with the measured acidities of 0·38 and 0·48 mmol H+ (g clay)−1. Samples VI and VII, prepared by reflux in acid, contained 0·3 and 0·1 mmol H+ (g clay)−1, respectively, and gave combined product yields of 13·0 and 6·0%.
Thermogravimetric and infrared study of the desorption of butylamine, cyclohexylamine and pyridine from Ni- and Co-exchanged montmorillonite
Authors: Breen C.
Published: November 2006

The acidity of Ni2+- and Co2+-exchanged montmorillonite has been probed using the diagnostic bases n-butylamine, cyclohexylamine and pyridine. Derivative thermograms for the desorption of pyridine from Ni2+- and Co2+-exchanged montmorillonite exhibited strong maxima at 40°, 90° and 360°C together with a weak maximum near 170°C The desorption maximum at 360°C is usually attributed to desorption of base from Bronsted acid sites. However, IR spectra of pyridine adsorbed on Ni2+- and Co2+-exchanged montmorillonite, at 250°C were dominated by intense bands near 1450 and 1607 cm−1 which are diagnostic of Lewis-bound pyridine. Consequently, the desorption maximum at 360°C must, in this instance, be attributed to desorption of pyridine from Lewis acid centres. Other bases, including cyclohexylamine and butylamine, also desorb at temperatures which have previously been attributed to the desorption of protonated base. Ni2+- and Co2+-exchanged clay contained predominatly Lewis acid or electron accepting sites, which is in marked contrast to the behaviour of trivalent cation exchanged clays.
Non-crystalline hydrous feldspathoids in Late Permian carbonate rock
Authors: Bender Koch C.
Published: November 2006

The EDTA-insoluble residues from five samples (two from the oolitic shoal facies and three from the lagoonal facies) of the Late Permian Ca-2 unit (Zechstein) have been investigated by X-ray diffraction, infrared spectroscopy, and scanning and transmission electron microscopy with energy dispersive X-ray analysis (EDXA). The results show that spheres of non-crystalline hydrous feldspathoids (with Al/Si molar ratio between 1·5 and 2·2) dominate the residues of samples from the oolitic shoal facies. Samples from the lagoonal facies are dominated by crystalline material (muscovite and quartz), but two of the samples contain a small number of spheres. Analyses of these samples by selective area diffraction and EDXA revealed the presence of small amounts of non-crystalline hydrous feldspathoids with Al/Si molar ratio between 0·1 and 1·9.
Effects of dry grinding on two kaolins of different degrees of crystallinity
Authors: Gonzalez Garcia F. , Ruiz Abrio M. T. , Gonzalez Rodriguez M.
Published: November 2006

Grain-size distribution, specific surface, thermal analysis, electron microscopy and X-ray diffraction were used to study the effect of dry grinding on the structure and properties of two kaolins of different degree of crystallinity. Grinding caused particles to fragment and resulted in the formation of stable large spheroidal aggregates of fine particles. These two processes were not clearly separated by a specific grinding time, but occurred in parallel shortly after grinding was started, although aggregate formation persisted at longer grinding times. The variation in the specific surface area during grinding was found to be dependent on these two processes and on the particle size and crystallinity of the initial kaolin. DTA and XRD data and the amount of water released at different temperatures revealed grinding to gradually destroy the kaolinite structure and cause the loss of hydroxyl ions and the formation of others that were subsequently removed at low and medium temperatures. An explanation for the process whereby the new hydroxyl ions are formed is provided.
Additive-free Hydrothermal Synthesis of High Aspect Ratio ZnO Particles from Aqueous Solution
Authors: Elen Ken , Van Bael Marlies K , Van den Rul Heidi , D’Haen Jan , Mullens Jules
Published: November 2006

In this work, a new hydrothermal process is described, in which, for the first time, an aquatic Zn2+ precursor is used for the synthesis of high aspect ratio ZnO particles, without the presence of any organic additive. Characterization of the particles is carried out by XRD, TEM, and SAED. Also the influence of different reaction times and of another reaction medium on the morphology and the dimensions of the rods is investigated.
Improving MEA Durability by Using a Catalyst with a Small Number of Functional Groups on Its Surface
Authors: Tanuma Toshihiro , Terazono Shinji
Published: November 2006

In order to improve the durability of MEAs, surface functional groups on catalysts were focused. It was found that functional groups such as hydroxy and carboxyl groups are responsible for the OCV degradation of MEAs. By applying a heat-treated catalyst, which has a small number of functional groups on its surface, to both cathode and anode of an MEA, the OCV durability was drastically improved.
Synthesis of 1,1′-Binaphthyl-2,2′-diyl Phosphoroselenoic Amides and Their Conversion to Optically Pure Phosphoramidites
Authors: Murai Toshiaki , Inaji Shinsuke , Morishita Ken , Shibahara Fumitoshi , Tokunaga Makoto , Obora Yasushi , Tsuji Yasushi
Published: November 2006

Optically pure phosphoroselenoyl chloride was reacted with racemic amines to give phosphoroselenoic amides as two diastereomeric mixtures in high yields. The diastereomeric mixtures were separated by fractional recrystallization or by chromatography. Extrusion of the selenium atom from the separated amides led to diastereomerically pure phosphoramidites. The ability of the obtained amidites to act as optically active ligands was tested in the hydrogenation of an imine.
Hydrophobic Functionalization of Mesoporous SBA-15 with Polyisoprene as a New Drug Delivery System
Authors: Zhou Zhengyang , Zhu Shenmin , Zhang Di , Zhou Zhiping
Published: November 2006

A novel delivery carrier system has been successfully conducted based on the ordered mesoporous silica SBA-15 with hydrophobic polyisoprene polymerized in the pores network. It is interesting to find that the result system still holds a relatively large pore size (6.5 nm) and pore volume (0.72 cm3 g−1), which will benefit for the storage of drugs with relatively large molecules.
Indigenous Assimilation and Absorption in the United States and Australia
Authors: ELLINGHAUS KATHERINE
Published: November 2006

Using a comparative mode of analysis, this article offers a new perspective on Indian assimilation policy in the United States. It focuses on one aspect of assimilation policy common to the United States and Australia in the late nineteenth and early twentieth centuries-the practice of removing indigenous children from their families and communities and placing them in institutions. The article argues that there is a subtle difference in the way that Americans and Australians described "assimilation"taking place-namely, the extent to which white Americans and white Australians openly planned to "whitewash" indigenous identity through interracial relationships. Nevertheless, while children of mixed descent played a very different role in the grandiloquent words used by reformers and politicians to describe their nation's policies,similar ideas about their role in the absorption and eventual disappearance of the indigenous population into the white one can be discerned in both contexts.
Fouling Mechanisms in a Laboratory‐Scale UV Disinfection System
Authors: Nessim Yoel , Gehr Ronald
Published: November 2006

The fouling of quartz sleeves surrounding UV disinfection lamps is a perennial problem affecting both drinking water and wastewater applications. The mechanisms of fouling are not fully understood, but factors promoting fouling are believed to include heat, high hardness and/or high iron concentrations, and hydrodynamic forces. The role of UV radiation itself is unclear. The goal of this paper is to attempt to isolate the fouling mechanisms and to provide key information about those induced by UV radiation, using a unique laboratory‐scale continuous‐flow UV reactor. Its design allowed for irradiated and nonirradiated zones and control of both temperature and UV intensity at the fouling surface. Synthetic wastewater samples were tested with two levels of calcium, iron, phosphorus, and biochemical oxygen demand (as beef broth), and constant levels of magnesium and nitrogen to assess the effects of the four key variables. Average UV fluence before fouling exceeded 35 mJ/cm2, based on collimated beam tests. Foulant accumulation was monitored by UV intensity measurements and by mass and composition of foulant collected after an average of 56 hours of continuous operation. Tests showed that relative UV intensity dropped by as much as 100% when iron was present. Detailed results were assessed and yielded support for the following three UV‐induced fouling mechanisms: (a) precipitation of ferric hydroxide [Fe(OH)3], (b) release of calcium from calcium‐organics complexes followed by precipitation of iron‐organics complexes, and (c) calcium carbonate precipitation. Other fouling mechanisms, such as sedimentation of preformed particles and sorption of calcium onto preformed colloids of Fe(OH)3, occurred outside the zone of UV radiation. Hence, these could be confused with concurrent UV‐induced mechanisms in full‐scale reactors. Iron and/or calcium undoubtedly created the most favorable conditions for fouling to occur; in the absence of both, fouling would be unlikely. The rates of fouling were enhanced when organics were also present; however, when phosphorus was present, fouling in the UV section was reduced. Indeed, UV may be viewed as inhibiting the fouling caused by phosphate complexes.
Protecting Human Subjects of Research: An Analysis on Proposed Amendments to HEW Policy
Authors: de Sola Pool Ithiel
Published: November 2006

Editor's Note: The Department of Health, Education and Welfare has prepared amendments to regulations governing research on human subjects. The regulations were established in response to recommendations from the National Commission for the Protection of Human Subjects of Biomedicai and Behavioral Research. These regulations are implemented by the institutional review boards established by colleges, universities and research institutes. The intent of the proposed amendments is admirable: to reduce the categories of research coming under federal control and review. But specific amendments could impose restrictions and difficulties upon political scientists conducting research projects or teaching their students to conduct research.

The Association's Council's concerns about the proposed regulations was expressed in this resolution passed on August 30:

While endorsing the important goal of protecting human subjects of research from abuse or injury, the APSA opposes any existing or proposed regulations or procedures relating to institutional review boards that would represent a threat to academic freedom or research or freedom of speech. The Council asks the Executive Director, in cooperation with other social science associations and higher education associations to prepare and present analysts of the implications of existing and proposed research regulations for political scientists and other social scientists.

Ithiel de Sola Pool has prepared the following analysis of the proposed regulations in order to inform colleagues of their possible impact. Political scientists who share his concerns are invited to write to the Executive Director of the APSA and join in forming a Committee of Concern about Institutional Review Board Practices by writing to: Ithiel de Sola Pool, 105 Irving Street, Cambridge, Massachusetts 02138.

The “Proposed Regulations Amending Basic HEW Policy for Protection of Human Research Subjects” which were published in the Federal Register of Tuesday, August 14, 1979, represent a substantial improvement over previous rules and draft rules, but are still grossly improper and unconstitutional.
Scattering properties for a pair of Schrödinger type operators on cylindrical domains
Authors: Melgaard Michael
Published: November 2006

Strong asymptotic completeness is shown for a pair of Schrödinger type operators on a cylindrical Lipschitz domain. A key ingredient is a limiting absorption principle valid in a scale of weighted (local) Sobolev spaces with respect to the uniform topology. The results are based on a refined version of Mourre’s method within the context of pseudo-selfadjoint operators.
SIRE-1, A putative plant retrovirus is closely related to a legume TY1-copia retrotransposon family
Authors: Pearce Stephen
Published: November 2006

SIRE-1 is a potential soybean retrovirus which has a gene order similar to Ty1-copia retrotransposons but also contains an envelope-like open reading frame (ORF), which is characteristic of retroviruses. PCR and Southern analysis reveals that SIRE-1 is closely related to a legume-wide family of envelope-lacking Ty1-copia group retrotransposons which suggests that SIRE-1 was formed by the recent acquisition of an envelope gene by a Ty1-copia retrotransposon.
Ischemic heart failure enhances endogenous myocardial apelin and APJ receptor expression
Authors: Atluri Pavan , Morine Kevin , Liao George , Panlilio Corinna , Berry Mark , Hsu Vivian , Hiesinger William , Cohen Jeffrey , Joseph Woo Y.
Published: November 2006

Apelin interacts with the APJ receptor to enhance inotropy. In heart failure, apelin-APJ coupling may provide a means of enhancing myocardial function. The alterations in apelin and APJ receptor concentrations with ischemic cardiomyopathy are poorly understood. We investigated the compensatory changes in endogenous apelin and APJ levels in the setting of ischemic cardiomyopathy.

Male, Lewis rats underwent LAD ligation and progressed into heart failure over 6 weeks. Corresponding animals underwent sham thoracotomy as control. Six weeks after initial surgery, the animals underwent hemodynamic functional analysis in the presence of exogenous apelin-13 infusion and the hearts were explanted for western blot and enzyme immunoassay analysis.

Western blot analysis of myocardial APJ concentration demonstrated increased APJ receptor protein levels with heart failure (1890750±133500 vs. 901600±143120 intensity units, n=8, p=0.00001). Total apelin protein levels increased with ischemic heart failure as demonstrated by enzyme immunoassay (12.0±4.6 vs. 1.0±1.2 ng/ml, n=5, p=0.006) and western blot (1579400±477733 vs. 943000±157600 intensity units, n=10, p=0.008). Infusion of apelin-13 significantly enhanced myocardial function in sham and failing hearts. We conclude that total myocardial apelin and APJ receptor levels increase in compensation for ischemic cardiomyopathy.
Mesocestoides litteratus (Batsch, 1786) (Cestoda: Cyclophyllidea: Mesocestoididae) from the red fox: Morphological and 18S rDNA characterization of European isolates
Authors: Literák I. , Tenora F. , Letková V. , Goldová M. , Torres J. , Olson P.
Published: November 2006

Mesocestoides litteratus (Batsch, 1786) (Cestoda: Cyclophyllidea: Mesocestoidae) is a common parasite of the red fox (Vulpes vulpes) and other carnivores across Europe. There has been considerable debate as to the validity of M. litteratus and other closely related, often sympatric species of Mesocestoides. We examine isolates of M. litteratus from red foxes in the Czech Republic, Slovakia and Spain both morphometrically and by characterization of 18S rDNA. Morphometric ranges of all isolates confirmed their identity as M. litteratus and were usually within the range published formerly. The sequences of 18S rDNA of one or two isolates from each country were analysed. The sequences were the same and distinct from all published Mesocestoides 18S sequences with the exception of tetrathyridia from a lizard in the Czech Republic, which was identical to those of M. litteratus.
Genetic structuring and differentiation of Echinococcus multilocularis in Slovakia assessed by sequencing and isoenzyme studies
Authors: Šnábel V. , Miterpáková M. , D’Amelio S. , Busi M. , Bartková D. , Turčeková L’. , Maddox-Hyttel C. , Skuce P. , Dubinský P.
Published: November 2006

Nucleotide sequencing of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene and isoenzyme analysis were used to survey the genetic variability in Echinococcus multilocularis populations from Slovakia. A sample of 12 isolates acquired from 10 different districts from red foxes exhibited identical sequences. Compared with the previously described E. multilocularis variants, one base substitution was consistently observed relative to the M1 variant (detected in China, Alaska, North America, Japan) and three base substitutions were recorded relative to the M2 variant (detected in Germany) in the CO1 fragment. These data, along with the recently gathered data from French isolates, are indicative of a genetically unique population occurring in Central and Western Europe. Electrophoretic examination of enzymes produced by 14 gene loci revealed intraspecific polymorphism only with the glucose-phosphate isomerase (two distinct patterns) and the mannosephosphate isomerase (four genotypes composed of three alleles) enzyme systems. To allow a fast species differentiation of E. multilocularis and E. granulosus (specifically, the G7 genotype occurring in Slovakia), discriminative electrophoretic characters between the species were obtained by isoenzyme analysis. Fixed genetic differences between the species were detected in the glucose-phosphate isomerase, esterase and aldolase systems, and partial differences were detected in four additional systems.
The presence of Syphacia obvelata in laboratory mice (BALB/c) — parasite antigens in immune response
Authors: Perec A. , Okulewicz A.
Published: November 2006

In conventional mice colonies, mouse pinworm, Syphacia obvelata is found very often. Several studies indicate that infection with this parasite can modulate the immune system of the host and can affect experimental final results. The aim of our study was to investigate the most immunogenic proteins of S. obvelata inducing both local and systemic immune response in naturally infected laboratory mice. Protein extracts of S. obvelata were analysed by Western blotting to examine their antigenic character. The antigens were probed with serum and mucosa of S. obvelata naturally infected mice. Surface and somatic antigens were recognized by serum and mucosal IgG, IgA and IgM antibodies. The most immunogenic and dominant proteins were observed. Proteins of Mw ∼ 70, 65 and 48 kDa showed the most evident reaction with serum and mucosa antibodies of infected animals. Surface and somatic antigens of nematode S. obvelata eliciting immune response in laboratory mice may be useful in development of a diagnostic test which could be applied for the infection control prior the experiments.
The fine structures of Cystocaulus ocreatus (Nematoda: Protostrongylidae) and the related lung pathology
Authors: Yildiz K. , Karahan S. , Cavusoglu K.
Published: November 2006

In the present study, the fine surface structures of Cystocaulus ocreatus and its worm as well as brood nodules obtained from the lung of Akkaraman sheep are demonstrated by scanning electron and light microscopy. The mouth of the parasite obtained from the worm nodules is located at the anterior tip and encircled by a collar of tissue. The mouth opening appears as three slits conjoined in the shape of a capital case letter Y, creating three lips. The mouth is surrounded by six papillae just behind the collar. The anterior end was similar in both sexes and covered by numerous wrinkles. Female parasite has a bell-shaped pro-vagina. The posterior end of the female parasite was sharply pointed. The male parasite has a bursa. In the worm nodule, curled parasites were enclosed by a capsula and no eggs and larvae of the parasite were observed. In the brood nodule, heavily affected alveoli and bronchioles contained excessive amounts of larvae and eggs.
Long-term variation in an occurrence of Rhabditis orbitalis parasitic larvae (Nematoda, Rhabditidae) in the eyes of montane rodents
Authors: Kocianová-Adamcová M. , Špakulová M. , Kocianová E.
Published: November 2006

During a long-term survey (1999–2005) of parasitic larvae of nidicolous nematode Rhabditis orbitalis Sudhaus et Schulte, 1986 in the West Tatra Mts, the nematodes were detected in the eye orbits of snow voles Chionomys nivalis in 1999, 2004 and 2005. In the last year, R. orbitalis was detected also in another vole species Clethrionomys glareolus and Microtus tatricus both in previously studied site and in the Low Tatra Mts, however, it has never appeared at other rodent species. For the first time, an irregular occurrence of the R. orbitalis parasitic larvae has been ascertained in natural conditions of the Slovak mountains. The eye nematodes occurred only during autumn or cold and rather wet summer months, when density of the preferred host Ch. nivalis was relatively low. A hypothesis has been put forward that an occasional appearance of parasitic eye larvae in the life cycle of bacteriophagous R. orbitalis represents a strategy for surviving periods of a scarcity of bacterial food, which could be influenced by a combination of weather conditions, density of host rodents and seasonal abundance of R. orbitalis in rodent nests.