bluuebunny/crossref_metadata_2025 huggingface dataset:
Direction of the cosmic ray anisotropy
Authors: Sandström Arne Eld , Dyring Eric , Lindgren Stig
Published: January 2012

Inclined meson telescopes at Uppsala, Kiruna, and Murchison Bay have been employed to determine the direction of the C.R. diurnal anisotropy. The six mean asymptotic directions are distributed between approximately 15° N and 80° N. It is being shown that the flow of excess particles responsible for the anisotropy is parallel to the orbital plane of the earth. All atmospheric effects have been considered as well as the partial smoothing out of the diurnal variation through the longitudinal distribution of the asymptotic directions. Inside the limits of error the yearly mean amplitudes fit a linear function of the cosine of the angle between the equatorial plane and the mean asymptotic direction. The direction of the anisotropy makes an angle of approximately 90° with the earth-sun line, the flow of excess particles overtaking the earth.
The influence of exchange of sensible heat with the earth’s surface on the planetary flow
Authors: Döös Bo R.
Published: January 2012

The exchange of sensible heat with the earth’s surface is one of the most important external forces which influence the motion of the atmosphere. This is studied with the aid of a linearized model, where the heating is assumed to be proportional to the difference between the temperature of the air at the bottom of the atmosphere and the temperature of the underlying surface. Since the temperature of the air is one of the dependent variables. the heating is dependent on the motion. The vertical decrease of the heating is given by a power function. Stationary disturbances on the zonal flow are evaluated for a simple temperature distribution of the ground which corresponds to conditions in middle latitudes in winter, which result from the effects of two continents and two oceans. The resulting horizontal distribution of the heat sources and sinks is evaluated. It is found that the positions of the heat sources are about 30° to the west of the temperature maximum of the underlying surface. The influence of friction, the vertical variation of the heating and the zonal wind profile are studied separately. The longitudinal variation of the heating along 45° N is compared with the normal sensible heat transfer in winter estimated from observations. Good agreement is obtained both regarding the magnitude of the heating and the phase difference between the heating and the ground temperature fields.
Early radioactive fallout in Israel following the 1961 nuclear weapon tests
Authors: Gat J. R. , Feige Y. , Pazy N. , Rosintal N.
Published: January 2012

Daily samples of airborne and deposited radioactivity were collected in Israel during the months following the 1961 nuclear weapon tests. The age and composition of the fallout was determined by radiochemical end decay analysis. Meteorological analysis of the data shows that except for one cam of direct cross-European transport, the favoured path of arrival of the early redioactive fallout into the Levant was by a circumpolar route in the upper troposphere. From December 1961 onwards there is evidenoe for increasing stratospheric contribution to the collected radioactivity.
A numerical forecast of fluid motion in a rotating tank and a study of how finite-difference approximations affect non-linear interactions
Authors: Sundqvist Hilding
Published: January 2012

Using observational data of the fluid motion in a laboratory experiment with a rotating tank numerical forecasts with three different models were made. The Ekman friction waa taken into account. The forecaats were verified statistically and the results for the different models were compared. An investigation of the effect of observational errors was made and it was found that errors in the initial field do not affect the prediction severely. The spectral distribution of kinetic energy in the forecast data and the verification data were compared. Systematic differences between observed and forecast distributions stimulated a study of the effect of finite differences on non-linear interactions. A theoretical discussion shows that when finite differences are applied to the nonlinear vorticity equation a leakage of energy from the long waves to the shortest ones occurs. To test this conclusion a numerical forecast was made with three different grid intervals, as well as a forecast of the Fourier components of the field of motion. Finally, it is discussed how the fictitious flow of energy may give rise to the special kind of computational instability that Phillips has investigated.
The exact solution of the Rossby adjustment problem
Authors: Mihaljan John M.
Published: January 2012

The exact solution of the ROSSBY (1938) adjustment problem is obtained. If a is the half-width of the initial current and λ is the radius of deformation, it is shown that Rossby’s solution is asymptotically valid for a/λ ⪡ 1. We examine the asymptotic solution for a/λ ⪢ 1. The exact energetic relations are obtained. The numerical examples of Rossby are recalculated with the exact solution.
Atmospheric tritium as a tool for the study of certain hydrologic aspects of river basins
Authors: Eriksson Erik
Published: January 2012

In thie paper a method is demonstrated by which the hydrological characteristics of a river baain are computed from a knowledge of added bomb-produced tritium in precipitation and tritium in run-off. It is also demonstrated that the hydrological characteristics thus computed agree well with the physiography and geology of the basin.
Comparative numerical integration of simple atmospheric models on a spherical grid
Authors: Gates W. Lawrence , Riegel Christopher A.
Published: January 2012

The non-divergent barotropic model, the two-layer quasi-geostrophic baroclinic model, and the two-layer balanced baroclinic model of variable static stability are integrated in parallel on a spherical grid with comparable boundary and initial conditions for the case of 00 GCT,3 7 December 1957. The integrations of the barotropic and quasi-geostrophic models show the expected accuracy decay to 72 hr, characterized by excessive momentum transport into the jet and an overall failure to predict significant baroclinic development. The balanced model displays an initially similar behavior, although the vertical motions are about twice those of the quasi-geostrophic case. Beyond 12 hr the balanced model’s vertical motions become excessively cellular and of increased magnitude, and a progressively serious distortion of the solutions takes place by 24 hr. The energy transformations of the variable-stability model indicate a disturbance evolution significantly different from that of the quasi-geostrophic model, although beyond 12 hr these transformations are themselves seriously influenced by the computed vertical motions. A number of recommendations for further tests are made, of which the improvement of the finite-difference schemes is probably the most important.
Finite amplitude convection in a conditionally unstable stagnant air mass
Authors: Haque S. M. A.
Published: January 2012

The steady-state non-linear equations of motion and heat transport for a conditionally unstable stagnant air mass between two plane horizontal boundaries are solved as a power series of a parameter of instability for the region of vertically upward motion of a disturbance symmetric about a vertical axis. For such a disturbance, which is known from previous studies to have the dimension of a typical cumulus cloud, it is shown that the magnitudes of the different velocity components in the state of maximum development will depend on the assumed values of the kinematic coefficient of eddy viscosity and the Prandtl number. Examples are given with some assumed values of these parameters in which the first term of the power series is calculated. The calculated values of the maximum vertical velocity seem to be of the same order of magnitude as in a typical cumulus cloud of moderate intensity. It is also seen that the disturbance will develop a component of the tangential velocity independent of height, which will be of the second order.
On the Role of the Tropics in the General Circulation of the Atmosphere
Authors: Riehl Herbert
Published: January 2012

Contrary to older descriptions, the air currents in the middle and upper
troposphere over the low latitudes are not steady but highly variable. There are trains
of well-developed waves or vortices. When these disturbances combine with troughs in the
polar westerlies, the resulting extended troughs often reach from pole to equator.
Poleward flow of heat must take place mainly along these troughs. Energy from low
latitudes is injected into the temperate zone in narrow and variable areas only.
A
description of the tropical atmosphere in the layers below and above the bases of the
cumuli leads to an attempt to explain the steadiness of the low-level wind field which
contrasts with the high variability of the upper layers. Then the strength of the mean
meridional circulation and the fields of divergence and convergence at the surface are
calculated, followed by a summary of available information on the high-level
circulation. The field of motion aloft varies greatly with longitude, so that inferences
concerning the tropics as a whole can only be made from maps covering most longitudes.
Such maps (300-mb charts) are available for a limited period down to latitude 10° N.
They indicate that regions where the easterlies decrease upward alternate with regions
of increasing easterlies.
The Variation of Gravity within the Earth
Authors: Saxov Svend
Published: January 2012

The different methods to determine the values of gravity within the Earth are reviewed. By using the equation g = g0 (r0/r)2 – 4/3 πGϱ r03–r3/r2 and substituting the density values tabulated by Ramsay the variation of gravity has been computed (table 1 and fig. 1). The g value of 982 gal at the surface of the Earth is attained without any correction to the density distribution.
Studies of the Equatorial Currents in the Pacific
Authors: Jerlov N. G.
Published: January 2012

Some dynamic results have been derived from oceanographic data collected in the equatorial currents in the Pacific Ocean during the Swedish Deep Sea Expedition. Horizontal current velocities geostrophically computed for three meridional sections bring out some characteristic features in the flow distribution within the Countercurrent. A survey of the mass transport of water from surface to 500 m depth reveals a slow eastward flow at 12°–15° N. The reality of this weak additional countercurrent is, however, not clearly established.
On the Relation between Vorticity, Deformation and Divergence and the Configuration of the Pressure Field
Authors: Petterssen Sverre
Published: January 2012

Theorems for the vorticity, deformation and divergence are developed for quasi-horizontal frictionless motion. The divergence theorem is used to investigate the validity of the geostrophic approximation, and it is found that the balance between the Laplacian of the pressure field and the vorticity is appreciably influenced by the deformation, while the divergence is relatively unimportant. The vorticity theorem and the deformation theorem are combined to obtain a prediction quantity which is related to the absolute vorticity and permits treatment of the fields which are more general than the geostrophic field. Some charts are produced to show the magnitudes of the various quantities in a mature storm.
A Remark on the Energy Transport from a Warm River Surface into Cold Air
Authors: Nyberg A. , Raab L.
Published: January 2012

Temperature measurements in very cold air above an open river surface indicate that in spite of very high temperature lapse rate (temperature of river, in the 2 cm, 10 cm, and 12 m levels are + 0.5, –14.0, –15.3, and –18.0° C respectively), the eddy conductivity is of the same order of magnitude as in extremely stable conditions (e. g. above a snow surface during nocturnal cooling).
The Use of the Primitive Equations of Motion in Numerical Prediction
Authors: Charney J.
Published: January 2012

An obstacle to the use of the primitive hydrodynamical equations for numerical prediction is that the initial wind and pressure fields determined by conventional means give rise to spurious large-amplitude inertio-gravitational oscillations which obscure the meteorologically significant large-scale motions. It is shown how this difficulty may be overcome by the use of a relationship between wind and pressure which enables one to determine these fields in such a manner that the noise motions do not arise. The method is illustrated by a numerically computed example.

The wind-pressure relationship is in a sense a generalization of the geostrophic approximation and may be used where the latter approximation is inapplicable, either to determine initial conditions or to derive a set of filtering equations for numerical prediction analogous to the quasi-geostrophic equations.
Experimental Evidence of the Directional Components of Cosmic Rays
Authors: Sandström Arne Eld
Published: January 2012

It is possible to resolve the diurnal variation into two components. The first of these has its maximum at 18h and corresponds to the particle wind predicted in the theory by ALFVÉN (1954). The amplitude ought to be constant both as a function of geomagnetic activity and as a function of time. The second component has its maximum at 12h. It represents the sum of the various kinds of radial particle flow, and it ought to display variations indirectly related to geomagnetic activity. A search for experimental evidence of these components is made possible through the determination of the incidental directions of the primary particles by BRUNBERG (1953) and BRUNBERG and DATTNER (1953). An analysis of C.R. measurements from Stockholm, Nagoya, and Huancayo seems to confirm the two components and their expected properties. A very doubtful amplitude change of the 18h-component during major magnetic storms is not at variance with theory. The Stockholm measurements were treated by SANDSTRÖM (1955) as to geomagnetic effects, those from Nagoya and Huancayo by SEKIDO and KODAMA (1952). A seasonal phase shift reported by the latter for geomagnetically quiet days is compared to measurements in Stockholm. If it exists at all the reported phase shift is evidently due to local effects. Other secular or seasonal phase shifts (ELLIOT and THAMBYAPHILLAI 1953) have not been treated in the present study, as the data did not provide any example of these effects. Several points are open to discussion because of the data’s being collected with instruments of widely different properties. Directional counter telescopes offer the most valuable results, if they are designed for a comparatively small aperture and measure in at least two directions.
Focusing of Paraxial Rays in a Magnetic Dipole Field
Authors: Åström Ernst
Published: January 2012

It is well known that a magnetic field of axial symmetry has a focusing effect for paraxial orbits. The field of the earth is of this type and it is shown that, if the cosmic rays consist of protons, a bundle of orbits parallel at infinite distance is focused on the surface of the earth if the energy is about to GeV. The co-latitude of the bundle at infinite distance is about 2.2 times the co-latitude of the focal point. The asymptote to the orbits is about 22° further to the east than the focal point. There is also an infinite series of lower energies exhibiting focusing properties. The calculations refer to paraxial orbits, but a comparison with terrella measurements shows that the focal energy and the above relation between the co-latitudes is appropriate down to about 50° latitude.
Carbon Dioxide Exchange Between Atmosphere and Ocean and the Question of an Increase of Atmospheric CO2 during the Past Decades
Authors: Revelle Roger , Suess Hans E.
Published: January 2012

From a comparison of C14/C12 and C13/C12 ratios in wood and in marine material and from a slight decrease of the C14 concentration in terrestrial plants over the past 50 years it can be concluded that the average lifetime of a CO2 molecule in the atmosphere before it is dissolved into the sea is of the order of 10 years. This means that most of the CO2 released by artificial fuel combustion since the beginning of the industrial revolution must have been absorbed by the oceans. The increase of atmospheric CO2 from this cause is at present small but may become significant during future decades if industrial fuel combustion continues to rise exponentially. Present data on the total amount of CO2 in the atmosphere, on the rates and mechanisms of exchange, and on possible fluctuations in terrestrial and marine organic carbon, are inadequate for accurate measurement of future changes in atmospheric CO2. An opportunity exists during the International Geophysical Year to obtain much of the necessary information.
Atmospheric Sea-Salt Nuclei Data for Project Shower
Authors: Woodcock A. H.
Published: January 2012

This report presents, without discussion, extensive data on the distribution of sea-salt nuclei in Hawaii during the field activities of Project Shower. References to studies and digests of similar data from this region are given. It is pointed out that one of the major purposes of obtaining these data, simultaneously with the other data presented in this volume, was to test an hypothesis of raindrop formation by tracing the salts in the nuclei to the salts in solution in the raindrops. The reader is invited to use these data for this or other purposes.
Airway Activation of Formyl Peptide Receptors Inhibits Th1 and Th17 Cell Responses via Inhibition of Mediator Release from Immune and Inflammatory Cells and Maturation of Dendritic Cells
Authors: Tae You-Me , Park Hyun Taek , Moon Hyung-Geun , Kim You-Sun , Jeon Seong Gyu , Roh Tae-Young , Bae Yoe-Sik , Gho Yong Song , Ryu Sung Ho , Kwon Hyouk-Soo , Kim Yoon-Keun
Published: January 2012

Formyl peptide receptors (FPRs) are chemoattractant receptors that mediate inflammatory cell responses to infection. Recent evidence indicates that noneosinophilic asthma phenotypes can be developed by both Th1 and Th17 cell responses when exposed to LPS-containing allergens. In this study, we evaluated the effects of airway activation of FPRs by their synthetic agonist, Trp-Lys-Tyr-Met-Val-D-Met (W-peptide), on the development of Th1 and Th17 cell responses in a noneosinophilic asthma mouse model. A noneosinophilic asthma mouse model was generated by intranasal sensitization with 10 μg of LPS plus 75 μg of OVA on days 0, 1, 2, and 7. Mice were then challenged with 50 μg of OVA alone on days 14, 15, 21, and 22. W-peptide was administered during the sensitization period, and immune and inflammatory responses were evaluated after OVA challenge. Lung inflammation after OVA challenge was partly abolished by airway activation of FPRs during sensitization. Maturation of dendritic cells (DCs) and migration of DCs from the lung to lung-draining lymph nodes were inhibited by FPR activation. In addition, airway activation of FPRs inhibited allergen-specific T cell proliferation in the lymph nodes. Production of IL-12 and IL-6 (Th1- and Th17-polarizing cytokines) from lung DCs was decreased by airway activation of FPRs. This effect resulted in the inhibition of allergen-specific Th1 and Th17 cell responses. Airway activation of FPRs during sensitization effectively prevents the development of Th1 and Th17 cell responses induced by LPS-containing allergens via multiple mechanisms, such as inhibition of DC maturation and migration and the production of Th1- and Th7-polarizing cytokines.
The IL-7Rα Pathway Is Quantitatively and Functionally Altered in CD8 T Cells in Multiple Sclerosis
Authors: Kreft Karim L. , Verbraak Evert , Wierenga-Wolf Annet F. , van Meurs Marjan , Oostra Ben A. , Laman Jon D. , Hintzen Rogier Q.
Published: January 2012

The IL-7Rα single nucleotide polymorphism rs6897932 is associated with an increased risk for multiple sclerosis (MS). IL-7Rα is a promising candidate to be involved in autoimmunity, because it regulates T cell homeostasis, proliferation, and antiapoptotic signaling. However, the exact underlying mechanisms in the pathogenesis of MS are poorly understood. We investigated whether CD4 and CD8 lymphocyte subsets differed in IL-7Rα expression and functionality in 78 MS patients compared with 59 healthy controls (HC). A significantly higher frequency of IL-7Rα+ CD8 effector memory (CD8EM) was found in MS. Moreover, IL-7Rα membrane expression was significantly increased in MS in naive and memory CD8 (all p < 0.05) with a similar trend in CD8EM (p = 0.055). No correlation was found between the expression level or frequency of IL-7Rα+CD8+ and rs6897932 risk allele carriership. Upon IL-7 stimulation, MS patients had stronger STAT5 activation in CD8EM compared with HC. IL-7 stimulation had a differential effect on both mRNA and protein expression of granzyme A and granzyme B between MS and HC. Stainings of different lesions in postmortem MS brain material showed expression of IL-7 and CD8+IL-7Rα+ in preactive, but not in active, demyelinating MS lesions, indicating involvement of IL-7Rα+ lymphocytes in lesion development. The intralesional production of IL-7 in combination with the lower threshold for IL-7–induced cytotoxicity in MS may enhance the pathogenicity of these CD8 T cells. This is of special interest in light of the established demyelinating and cytotoxic actions of granzyme A.
Physically-based modelling of granular flows with Open Source GIS
Authors: Mergili M. , Schratz K. , Ostermann A. , Fellin W.
Published: January 2012

Abstract. Computer models, in combination with Geographic Information Sciences (GIS), play an important role in up-to-date studies of travel distance, impact area, velocity or energy of granular flows (e.g. snow or rock avalanches, flows of debris or mud). Simple empirical-statistical relationships or mass point models are frequently applied in GIS-based modelling environments. However, they are only appropriate for rough overviews at the regional scale. In detail, granular flows are highly complex processes and physically-based, distributed models are required for detailed studies of travel distance, velocity, and energy of such phenomena. One of the most advanced theories for understanding and modelling granular flows is the Savage-Hutter type model, a system of differential equations based on the conservation of mass and momentum. The equations have been solved for a number of idealized topographies, but only few attempts to find a solution for arbitrary topography or to integrate the model with GIS are known up to now. The work presented is understood as an initiative to integrate a fully physically-based model for the motion of granular flows, based on the extended Savage-Hutter theory, with GRASS, an Open Source GIS software package. The potentials of the model are highlighted, employing the Val Pola Rock Avalanche (Northern Italy, 1987) as the test event, and the limitations as well as the most urging needs for further research are discussed.
Molecular weight effect of PMMA on its miscibility with PS‐b‐PEO at the air/water interface
Authors: Jheng Kai‐Teng , Hsu Wen‐Ping
Published: January 2012

The mixed monolayer behavior of poly(methyl methacrylate) (PMMA) with different molecular weights and polystyrene‐block‐polyethylene oxide (PS‐b‐PEO) was investigated from the measurements of surface pressure–area per molecule (π‐A) isotherms at three different temperatures (10°C, 25°C, and 40°C). The miscibility and nonideality of the mixed monolayers were examined by calculating the excess surface area as a function of composition. The molecular weight of PMMA was demonstrated to have a major effect on its miscibility with PS‐b‐PEO. Negative or close to zero deviations from ideality of surface areas were observed for PMMA with the lowest molecular weight (12,000 g/mole). Mostly positive deviations were detected in mixed PMMA/PS‐b‐PEO monolayers with higher molecular weights of PMMA. Because of probable mushroom‐to‐brush transition effect, the miscibility between PMMA and PS‐b‐PEO was found to be the best at 25°C among the experimental temperatures. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Polymer‐based metal adsorbents via graft copolymerization of polyvinyl alcohol with diaminomaleonitrile: A green chemistry approach
Authors: Abdel‐Razik H. H. , Abbo M. , Almahy H. A.
Published: January 2012

Synthesis, characterization, and amidoximation of diaminomaleonitrile‐functionalized polyvinyl alcohol (PVA) grafts were studied. Ceric ammonium nitrate (CAN) was used as an initiator in an aqueous nitric acid medium under N2 atmosphere. Optimum conditions for grafting were as follows: monomer concentration [DAMN] = 1.4M, [CAN] = 16 × 10−2 mol/L, T = 50°C, and t = 2 h. Water uptake of the PVA graft films increased with the increase of grafting yield. The imparted cyano group of the grafted PVA polymer chains (with degree of grafting up to 136%) was converted into amidoxime group by the reaction with hydroxylamine hydrochloride. The grafted polymers were characterized by FTIR spectroscopy, differential scanning calorimetry, and thermal gravimetric analysis. The grafted PVA films are more thermally stable than the ungrafted PVA membrane, because the grafted membrane showed a single degradation pattern despite having two components. A decrease in Tg values is observed as the grafting yield of copolymers increases indicating the incorporation of polydiaminomaleonitrile chains in amorphous copolymers with higher thermal stability. The prepared amidoximated DAMN136‐g‐PVA was investigated for its properties in removing heavy toxic metals, such as Pb2+, Cd2+, Zn2+, Fe3+, Cu2+, Ni2+, and Co2+ from water. The amidoximated film is characterized by a considerably greater binding ability with respect to heavy metals. The nature of the metal ion also has great importance in the amount binding to the polymeric material. The kinetics of the sorption/desorption process for Co2+, Ni2+, and Zn2+ were investigated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Empirical modeling development for integrated process optimization of poly(3‐hydrxybutyrate‐co‐3‐hydroxyvalerate) production
Authors: Shantini K. , Yahya Ahmad R. M. , Amirul A. A.
Published: January 2012

The optimization of P(3HB‐co‐3HV) synthesis was investigated using response surface methodology (RSM). Primary experiments showed different concentrations of 1‐pentanol, agitation rates, and incubation times were the main factors influencing the production of this copolymer. To test the influence of the process parameters, two statistical experimental designs were performed. The first step of optimization used two‐level factorial designs to determine the significant variables affecting the growth and production. The RSM model was experimentally validated yielding a maximum of 65 wt % PHA content and 10.2 g/L cell dry weight, which represent 12.1% increase in PHA content in comparison to the non‐optimized condition using oleic acid and 1‐pentanol as the carbon source and carbon precursor, respectively. The experimental results showed that the RSM was a useful tool as the utilization of 1‐pentanol by Cupriavidus sp. USMAA2‐4 was reduced by 33%. A second‐order polynomial equation was obtained by multiple regression analysis to explain the combined effect of the three parameters with the coefficient of determination, R2, greater than 0.9. The optimum process conditions and interactions were determined by analyzing three‐dimensional surfaces. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Silk I structure formation through silk fibroin self‐assembly
Authors: Ming Jinfa , Zuo Baoqi
Published: January 2012

Regenerated silk fibroin films are normally produced by increasing the Silk II structure (β‐sheet content). In the present study, silk fibroin films were prepared by controlling the environmental temperature and humidity, resulting in the formation of silk films with a predominant Silk I structure instead of Silk II structure. Wide angle X‐ray diffraction indicated that when the relative humidity was 55%, the silk films prepared were mainly composed of Silk I structure, whereas silk films formed on other relative humidity had a higher Silk II structure. Fourier transform infrared analysis (FTIR) results also conformed that the secondary structure of silk fibroin can be controlled by changing the humidity of the films formed process. Thermal analysis results revealed Silk I structure was a stable crystal, and the degradation peak increased to 320°C, indicating a greater thermal stability of these films formed under the 55% relative humidity conditions. Atomic force microscopy (AFM) results depicted silk fibroin in the fresh solution had many nanospheres existing with 20–50 nm diameters and mainly maintained a random coil structure without specific nanostructures. At the same time, it also illustrated the self‐assembly process of silk fibroin in the aqueous solution without any human intervention. In addition, this present study also provided additional support for self‐assembly mechanism of silk fibroin films formation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Diazotization–cyanation of aromatic amines with crosslinked poly(4‐vinylpyridine)‐supported cyanide ions
Authors: Karimi Zarchi Mohammad Ali , Ebrahimi Nahid
Published: January 2012

A simple, mild, and efficient method for the cyanation of stable arenediazonium salts was developed with polymer‐supported cyanide. Arenediazonium hydrogen sulfate (ArN2+HSO4−) was obtained by the reaction between a primary aryl amine and sodium nitrite in the presence of concentrated sulfuric acid (H2SO4) at low temperature (0–5°C). By an ion‐exchange reaction between ArN2+HSO4− and NaBF4, the stable arenediazonium tetrafluoroborate, ArN2+BF4−, was prepared. ArN2+BF4− was then converted to aryl nitrile with crosslinked poly(4‐vinylpyridine) supported cyanide ion in acetonitrile at room temperature. The spent polymeric reagent was regenerated and reused several times without any loss in its activity. This procedure offered advantages, including a higher isolated yield, shorter reaction time, and simple reaction workup. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Bimetallic Catalysis using Transition and Group 11 Metals: An Emerging Tool for CC Coupling and Other Reactions
Authors: Pérez‐Temprano Mónica H. , Casares Juan A. , Espinet Pablo
Published: January 2012

Bimetallic catalysis refers to homogeneous processes in which either two transition metals (TM), or one TM and one Group 11 (G11) element (occasionally Hg also), cooperate in a synthetic process (often a CC coupling) and their actions are connected by a transmetalation step. This is an emerging research area that differs from the isolated or tandem applications of the now classic processes (Stille, Negishi, Suzuki, Hiyama, Heck). Most of the reactions used so far combine Pd with a second metal, often Cu or Au, but syntheses involving very different TM couples (e.g., Cr/Ni in the catalyzed vinylation of aldehydes) have also been developed. Further development of the topic will soon demand a good knowledge of the mechanisms involved in bimetallic catalysis, but this knowledge is very limited for catalytic processes. However, there is much information available, dispersed in the literature, coming from basic research on exchange reactions occurring out of any catalytic cycle, in polynuclear complexes. These are essentially the same processes expected to operate in the heart of the catalytic process. This Review gathers together these two usually isolated topics in order to stimulate synergy between the bimetallic research coming from more basic organometallic studies and the more synthetic organic approaches to this chemistry.
Ligand‐Modification Effects on the Reactivity, Solubility, and Stability of Organometallic Tantalum Complexes in Water
Authors: Conde Ana , Fandos Rosa , Hernández Carolina , Otero Antonio , Rodríguez Ana , Ruiz María José
Published: January 2012

Tantalum complexes [TaCp*Me{κ4‐C,N,O,O‐(OCH2)(OCHC(CH2NMe2)CH)py}] (4) and [TaCp*Me{κ4‐C,N,O,O‐(OCH2)(OCHC(CH2NH2)CH)py}] (5), which contain modified alkoxide pincer ligands, were synthesized from the reactions of [TaCp*Me{κ3‐N,O,O‐(OCH2)(OCH)py}] (Cp*=η5‐C5Me5) with HCCCH2NMe2 and HCCCH2NH2, respectively. The reactions of [TaCp*Me{κ4‐C,N,O,O‐(OCH2)(OCHC(Ph)CH)py}] (2) and [TaCp*Me{κ4‐C,N,O,O‐(OCH2)(OCHC(SiMe3)CH)py}] (3) with triflic acid (1:2 molar ratio) rendered the corresponding bis‐triflate derivatives [TaCp*(OTf)2{κ3‐N,O,O‐(OCH2)(OCHC(Ph)CH2)py}] (6) and [TaCp*(OTf)2{κ3‐N,O,O‐(OCH2)(OCHC(SiMe3)CH2)py}] (7), respectively. Complex 4 reacted with triflic acid in a 1:2 molar ratio to selectively yield the water‐soluble cationic complex [TaCp*(OTf){κ4‐C,N,O,O‐(OCH2)(OCHC(CH2NHMe2)CH)py}]OTf (8). Compound 8 reacted with water to afford the hydrolyzed complex [TaCp*(OH)(H2O){κ3‐N,O,O‐(OCH2)(OCHC(CH2NHMe2)CH2)py}](OTf)2 (9). Protonation of compound 8 with triflic acid gave the new tantalum compound [TaCp*(OTf){κ4‐C,N,O,O‐(OCH2)(HOCHC(CH2NHMe2)CH)py}](OTf)2 (10), which afforded the corresponding protonolysis derivative [TaCp*(OTf)2{κ3‐N,O,O‐(OCH2)(HOCHC(CH2NHMe2)CH2)py}](OTf) (11) in solution. Complex 8 reacted with CNtBu and potassium 2‐isocyanoacetate to give the corresponding iminoacyl derivatives 12 and 13, respectively. The molecular structures of complexes 5, 7, and 10 were established by single‐crystal X‐ray diffraction studies.
Virtual special issue on theory and research on collective action in the European Journal of Social Psychology
Authors: Becker Julia C.
Published: January 2012

This virtual special issue presents a collection of 23 articles that present theory and research on collective action in the European Journal of Social Psychology. The articles are organized according to four major themes that emerged. In the first section, articles on identification with the disadvantaged group, identification with the superordinate group, and identity content as predictors of collective action are summarized. The second section combines articles examining the role of sociostructural variables (permeability, legitimacy, and stability) for collective action. The third section comprises articles on the psychological implications of sociostructural variables (emotions, efficacy beliefs, threat perceptions) as predictors of collective action. In the final section, articles that highlight the dynamic perspective on collective action are presented. This issue contains articles on collective action conducted by disadvantaged groups, advantaged groups, and opinion‐based groups. After the conceptual overview, commonalities and distinctions between the articles are highlighted, and some directions for future research are outlined. Copyright © 2012 John Wiley & Sons, Ltd.
Constitutive expression of hydrophobin HFB1 from Trichoderma reesei in Pichia pastoris and its pre‐purification by foam separation during cultivation
Authors: Kottmeier Kirsten , Günther Tobias Jan , Weber Jost , Kurtz Susann , Ostermann Kai , Rödel Gerhard , Bley Thomas
Published: January 2012

Hydrophobins are small surface‐active proteins that have considerable potential for use in applications ranging from medical and technical coatings, separation technologies, biosensors, and personal care. Their wider use would be facilitated by the availability of recombinant tailor‐made hydrophobins. We successfully expressed the class II hydrophobin HFB1 from Trichoderma reesei in Pichia pastoris under the control of the constitutive GAP (glyceraldehyde 3‐phosphate dehydrogenase) promoter. Avoiding the use of the AOX1 (alcohol oxidase 1) promoter prevents the costs and risks associated with the storage and delivery of methanol used as an inducer. Efficient secretion of hydrophobin was achieved using either the alpha‐factor prepro‐peptide or the native secretion signal of HFB1. The secreted hydrophobins have been isolated with a purity of up to 70% using in situ foam separation during the cultivation process. Coating experiments and surface pressure measurements demonstrated the activity of the hydrophobins. An immunodot assay showed the accessibility of carboxyterminally fused tags of the hydrophobin, which is necessary for potential applications using functionalized hydrophobins. The presented data show that Pichia pastoris is a suitable system for production of constitutively expressed and secreted active hydrophobin, allowing for in situ pre‐purification using foam separation.
Design flood estimation in ungauged catchments and statistical characterization using principal components analysis: application of Gradex method in Upper Moulouya
Authors: Zemzami Mahmoud , Benaabidate Lahcen , Layan Badr , Dridri Abdallah
Published: January 2012

Design flood estimation in ungauged catchments is of great importance in hydrologic practice especially where there is no available data about streamflow. Except the watershed of Anseghmir who is equipped with a gauge station, all the other watersheds are ungauged catchments. The use of frequency analysis of series of rainfall and streamflow is very important for the characterization of the hydrologic resources of the Upper Moulouya. The region has a semiarid climate that requires a good knowledge of the watershed's potential water to assist policy makers in forecasting extreme events, managing water resources and decision making. The frequency analysis was used to determine the design flood of different return periods. The results obtained are used in Gradex method to estimate the hydrologic variables of each subcatchment of the Upper Moulouya. Once the hydrologic study is completed, a principal components analysis was made to highlight the affinities between the different subcatchments and to deduce the hydrologic and hydrographic parameters that better characterize them. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of cementing technique and cement type on thermal necrosis in hip resurfacing arthroplasty—a numerical study
Authors: Janssen Dennis , Srinivasan Priyanka , Scheerlinck Thierry , Verdonschot Nico
Published: January 2012

Femoral fractures within resurfacing implants have been associated with bone necrosis, possibly resulting from heat generated by cement polymerization. The amount of heat generated depends on cement mantle volume and type of cement. Using finite element analysis, the effect of cement type and volume on thermal necrosis was analyzed. Based on CT‐data of earlier implantations, two different models were created: a thick mantle model, representing a low‐viscosity “cement filling” technique, and a thin mantle model, representing a high viscosity “cement packing” technique. Six cement types were analyzed. The polymerization heat generation and its effect on bone necrosis were predicted. In the thin cement mantle models, no thermal necrosis was predicted. Thick cement mantle models produced thermal necrosis at the cement–bone interface depending on cement type. In the worst case, 6% of the bone at the cement–bone interface became necrotic, covering almost the entire cross‐sectional area. The current findings suggest a potential thermal drawback of thick cement mantles, although it is unclear whether thermal bone necrosis significantly affects implant fixation or increases the fracture risk. Furthermore, our study showed distinct differences between the heat generated and resulting thermal damage caused by the various cement types. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:364–370, 2012
Outcome models in peripheral nerve repair: Time for a reappraisal or for a novel?
Authors: Galanakos Spyridon P. , Zoubos Aristides B. , Johnson Elizabeth O. , Kanellopoulos Anastasios D. , Soucacos Panayotis N.
Published: January 2012

Peripheral nerve injuries are still underestimated. The complexity of assessment of outcome after nerve injury and repair has been described by many authors. Furthermore, the outcome is influenced by several factors that depend on mechanisms in the peripheral as well as the central nervous system. Appropriate formulation of a global accepted postoperative clinical protocol for peripheral nerve repair in the upper extremity remains a subject of debate. The purpose of this review is to detail the current concepts of methods of evaluation after peripheral nerves repair. Finally, we discuss the most crucial factors that determine the final hand function and we consider the challenges that need to be addressed to create a realistic clinical protocol that reflects a prognostic importance. © 2012 Wiley Periodicals, Inc. Microsurgery, 2012.
A multiband antenna array for WLAN/WiMAX applications
Authors: Lou Xi‐Zhong , Li Jiu‐Sheng
Published: January 2012

In this article, we proposed an antenna array with multiband for wireless local area network (WLAN)/WiMAX applications. The operating frequency band of the antenna covers the 2.4/5.2/5.8 GHz WLAN (2400–2484/5150–5350/5725–5875 MHz), and the 2.5/3.5/4.3/5.5 GHz/7.5 GHz WiMAX (2500–2690/3300–3800/4300–4990/5250–5850/6720–7790 MHz). This antenna has advantage of its simple configuration, low profile, compactness, and low fabrication cost. Microwave experiments and numerical simulations are performed to demonstrate its functionalities. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:664–667, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26598
Low cost and compact directional coupler for ultrawideband applications
Authors: Zaidel Dyg N. A. , Rahim Sharul K. A. , Seman Norhudah , Rahman Tharek A. , Abdulrahman A.
Published: January 2012

A design of a compact size (35 × 15 mm2) 3‐dB coupler with ultrawideband (UWB) characteristic is demonstrated in this article. The proposed design is accomplished by forming two diamond‐shaped microstrip lines that are broadside coupled by a slot at the middle ground plane. The dimension of the design was initialized using a simple mathematical formula and optimized using the CST microwave studio simulator. The design coupler is fabricated and measured. It shows comparable results of the simulation and measurement for the phase difference between two output ports, return loss, isolation, and 3‐dB coupling over an UWB frequency range between 4 and 8.34 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:670–674, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26616
A compact broadband ridged‐square‐waveguide radiating element for phased array antennas in synthetic aperture radar applications
Authors: Gao Wen‐Jun , Jiao Jun‐Jun , Han Yun‐Zhong , Deng Yun‐Kai , Xiong Yong‐Hu , Liu Xiao‐Meng
Published: January 2012

For broadband synthetic aperture radar applications, a compact broadband horn array antenna is investigated.Ridged waveguide and square horn are used for broadband operating, and the size of the array element is much smaller than the traditional horn. The measured operating frequencies covered all X‐band, more than 40% at centered frequency about 10 GHz. A 4 × 8 array was tested, and the measured results showed that the scan angle can be more than 15°, and the side lobe levels are −12 dB. Details of the antenna design and experimental results are presented. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:829–833, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26634
Defining achievable standards in urodynamics—a prospective study of initial resting pressures
Authors: Sullivan Jonathan G. , Swithinbank Lucy , Abrams Paul
Published: January 2012

Aims

Establishing accurate initial resting pressures is an important step in quality control at the start of a urodynamics test. We therefore carried out a prospective study to establish the initial resting pressures achievable with careful quality control.

Methods

Consecutive patients undergoing urodynamics were recruited. Initial resting pressures were recorded in lying, sitting, and standing positions for each patient. The detrusor pressure values obtained before filling were then compared with the pressures obtained during filling.

Results

Initial resting abdominal and intravesical pressures were similar and at least 95% lay in the following ranges: lying 0–18 cmH2O, sitting 15–40 cmH2O, standing 20–50 cmH2O: these data gave initial resting detrusor pressure readings between −5 and +5 cmH2O in 97%, 97%, and 96%, respectively. Comparison of initial resting pressure readings with those obtained during filling showed that the narrow range of pressures was maintained during the urodynamic test.

Conclusions

This study provides detailed prospective data on achievable initial resting pressures in urodynamics. In this study, pdet was normally at or close to zero, and distributed more or less evenly either side. This suggests a range that differs from existing ICS GUP guidelines, and could be incorporated in future ICS guidelines. Neurourol. Urodynam. 31:535–540, 2012. © 2012 Wiley Periodicals, Inc.
Molecular beam epitaxy of GaN1–xBix alloys with high bismuth content
Authors: Novikov S. V. , Yu K. M. , Levander A. X. , Liliental‐Weber Z. , dos Reis R. , Kent A. J. , Tseng A. , Dubon O. D. , Wu J. , Denlinger J. , Walukiewicz W. , Luckert F. , Edwards P. R. , Martin R. W. , Foxon C. T.
Published: January 2012

We have analysed bismuth incorporation into GaN layers using plasma‐assisted molecular beam epitaxy (PA‐MBE) at extremely low growth temperatures of less than ∼100 °C under both Ga‐rich and N‐rich growth conditions. The formation of amorphous GaN1−xBix alloys is promoted by growth under Ga‐rich conditions. The amorphous matrix has a short‐range order resembling random crystalline GaN1−xBix alloys. We have observed the formation of small crystalline clusters embedded into amorphous GaN1−xBix alloys. Despite the fact that the films are pseudo‐amorphous we observe a well defined optical absorption edges that rapidly shift to very low energy of ∼1 eV.
Electron transport properties in Al0.25Ga0.75N/AlN/GaN heterostructures with different InGaN back barrier layers and GaN channel thicknesses grown by MOCVD
Authors: Kelekçi Özgür , Taşlı Pınar T. , Yu HongBo , Kasap Mehmet , Özçelik Süleyman , Özbay Ekmel
Published: January 2012

The electron transport properties in Al0.25Ga0.75N/AlN/GaN/InxGa1−xN/GaN double heterostructures with various indium compositions and GaN channel thicknesses were investigated. Samples were grown on c‐plane sapphire substrates by MOCVD and evaluated using variable temperature Hall effect measurements. In order to understand the observed transport properties, various scattering mechanisms, such as acoustic phonon, optical phonon, interface roughness, background impurity, and alloy disorder, were included in the theoretical model that was applied to the temperature‐dependent mobility data. It was found that low temperature (T < 160 K) mobility is limited only by the interface roughness scattering mechanism, while at high temperatures (T > 160 K), optical phonon scattering is the dominant scattering mechanism for AlGaN/AlN/GaN/InGaN/GaN heterostructures. The higher mobility of the structures with InGaN back barriers was attributed to the large conduction band discontinuity obtained at the channel/buffer interface, which leads to better electron confinement.
Effect of coalescence layer thickness on the properties of thin‐chip InGaN/GaN light emitting diodes with embedded photonic quasi‐crystal structures
Authors: Shields Philip A. , Charlton Martin D. B. , Lewins Christopher J. , Gao Xiang , Allsopp Duncan W. E. , Wang Wang N. , Humphreys Bedwyr
Published: January 2012

The simulation, fabrication and optical characterization of InGaN/GaN MQW‐LEDs grown by MOVPE over embedded photonic quasi‐crystals (PQCs) are reported. Fully coalesced GaN layers as thin as 140 nm were grown over 1200 nm high air‐gap PQCs using an intermittent pulsed/normal growth method. Simulations and angle‐resolved photoluminescence measurements reveal there are strong interactions between the embedded PQC and a wide range of trapped modes as well as the dominant low order mode. The interaction with a dominant low order mode is most pronounced when the LED cavity above the embedded PQC has fewer guided modes.

magnified image

1200 nm high embedded air‐gap PQC overgrown with a 280 nm thick coalesced GaN epitaxial layer by MOVPE.