bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Endosomolytic Properties of Poly(amidoamine) Block Copolymers
Authors: Lavignac Nathalie , Lazenby Michelle , Foka Peli , Malgesini Beatrice , Verpilio Ilario , Ferruti Paolo , Duncan Ruth
Published: October 2004

Summary: The poly(amidoamine)s (PAAs) ISA 1 and ISA 23 display pH‐dependent conformational change and pH‐dependent membrane perturbation. These properties confer potential for use as endosomolytic polymers for intracytoplasmic delivery of toxins and genes. Both polymers are relatively non‐toxic, and moreover ISA 23 has the beneficial property in vivo, of being non hepatotropic when administered intravenously. Although ISA 23 and ISA 1 demonstrate ability to transfect cells, ISA 1 is also able to promote intracellular delivery of non‐permeant toxins. The aim of this study was to synthesise random and block copolymers of ISA 1 and ISA 23 and investigate whether these second generation hybrids would allow optimisation of PAA biological characteristics. Random and block copolymers of ISA 1 and ISA 23 were synthesised by hydrogen transfer polyaddition to generate a library of PAAs with an ISA 23:ISA 1 molar ratios of 2:1 to 4:1. The resultant polymers have a pI slightly below 7.4 and a $\overline M _{\rm w}$ of 19 900–49 000 g/mol and a $\overline M _{\rm n}$ of 13 100–24 100 g/mol. Whereas none of the random or block copolymers were haemolytic at pH 7.4 all demonstrated pH‐dependent membrane activity. At pH 5.5 they caused 50–60% haemoglobin (Hb) release over 1 h. This was slightly less than that seen for ISA 23 (80% Hb release). None of the copolymers were cytotoxic against B16F10 cells during a 72 h incubation (IC50 > 2 mg/ml; MTT assay). The ability of the random and block copolymer PAAs to deliver the toxin gelonin was also examined, but only ISA 1 and the block copolymer B2 (ISA 23:ISA 1 at a 2:1 molar ratio) were able to promote intracellular delivery, as measured by cytotoxic activity. It would be interesting to study the body distribution of B2 and determine whether this toxin‐delivering PAA is able to escape liver capture.

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Opal Gels Templated Synthesis of Structured Titania Materials
Authors: Rong Jianhua , Ma Jin , Yang Zhenzhong
Published: October 2004

Summary: Core/shell opal gels of sulfonated polystyrene were used as templates to synthesize structured crystalline titania materials. Under acidic conditions, opal materials with hollow spheres of controllable shell thickness and cavity size were prepared. Under neutral conditions, inverse opal inorganic materials with a tunable pore size were prepared. It is crucial that proton ions induce a preferential sol/gel process, forming titania in the gel.

Scanning electron micrograph of the interior region of a structured titania material derived from the G1 template used here. The inset shows broken spheres in which the internal cavity can be observed.

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Scanning electron micrograph of the interior region of a structured titania material derived from the G1 template used here. The inset shows broken spheres in which the internal cavity can be observed.
Silk Sericin Retards the Crystallization of Silk Fibroin
Authors: Lee Ki Hoon
Published: October 2004

Summary: The thermal and structural analysis of silk fibroin (SF) and silk sericin (SS) blend films reveals that the crystallization of SF is retarded in the presence of SS. Although a phase separation was observed, there might be a strong interaction at the boundary of the SF and SS through intermolecular hydrogen bonding, which restricts the conformational transition of SF.

TEM image of the cross‐section of the SF/SS blend (75:25) film (magnification: ×15 000).

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TEM image of the cross‐section of the SF/SS blend (75:25) film (magnification: ×15 000).
Mass spectrometry in aging research
Authors: Schöneich Christian
Published: October 2004

This review covers the application of mass spectrometric techniques to aging research. Modern proteomic strategies will be discussed as well as the targeted analysis of specific proteins for the correlation of post‐translational modifications with protein function. Selected examples will show both the power and also current limitations of the respective techniques. Experimental results and strategies are discussed in view of current theories of the aging process. © 2004 Wiley Periodicals, Inc., Mass Spec Rev 24:701–718, 2005
Das β‐adrenerge System: Pharmakologische Aspekte
Authors: Hein Lutz
Published: October 2004

Das adrenerge System steuert eine Vielzahl von wichtigen physiologischen Funktionen im zentralen und im peripheren, sympathischen Nervensystem. Die beiden endoge‐nen Effektoren Noradrenalin und Adrenalin sind die Liganden für die Familie der adrenergen Rezeptoren mit insgesamt neun Mitgliedern. Dazu zählen drei Rezeptorsubtypen der α1‐Gruppe, drei α2‐Rezeptoren sowie die drei β‐Rezeptoren.
Die räumliche Betrachtung und Beschreibung von Nebivolol: Stereochemie der Beta‐Blocker
Authors: Siebert Carsten D.
Published: October 2004

Nebivolol ist ein in vieler Hinsicht interessantes Molekül. Sowohl der synergistische pharmakologische Effekt seiner beiden Enantiomere als auch die stereochemische Analyse zeigen sehr schön den Konnex zwischen Chemie und Pharmazie. Die im Lehrbetrieb sehr oft getrennt vermittelten Kenntnisse über die Synthese organisch‐chemischer Verbindungen, Analytik von Wirkstoffen, Stereochemie, Molekularpharmakologie und medizinischem Nutzen in der Pharmakotherapie kristallisieren sich beispielhaft an dem β1‐Adrenozeptor‐Antagonisten Nebivolol. Dabei stellt Nebivolol keineswegs einen besonderen Fall dar, analoge stereochemische Betrachtungen lassen sich z.B. auch an dem Muskelrelaxans Mivacuriumchlorid [1] anstellen.

In den letzten Jahren konnte an vielen Arzneistoffen anhand der dreidimensionalen Stuktur gezeigt werden, dass Enantiomeren oder Diastereomeren häufig eine unterschiedliche pharmakodynamische und pharmakokinetische Wirkung zukommt. Dies hat dazu geführt, dass der Anteil neu zugelassener Stereoisomeren‐reiner Pharmaka in den letzten fünf Jahren bei 60 % lag [5]. Dies zeigt deutlich, dass die exakte räumliche Beschreibung eines chemischen Moleküls zum grundlegenden Verständnis von Wirkaktivität gehört. In diesem Sinne ist Nebivolol ein Paradebeispiel für eine stereochemische Übung.
Verbesserte Therapie durch optimierte Arzneiformen?: Schnelle Freisetzung oder Retardformulierung?
Authors: Warnke André , Blume Henning
Published: October 2004

Als im Jahr 1964 Propranolol als erster β‐Rezeptorenblocker in die Therapie eingeführt wurde, war keineswegs vorauszusehen, dass dies den Ausgangspunkt für eine fulminante Entwicklung in der Arzneimittelforschung darstellen würde. Diese betraf in erster Linie die Synthese neuer Derivate mit grundsätzlich analoger Struktur, die alle über eine kompetitive Hemmung der durch β‐Rezeptoren vermittelten Effekte der Katecholamine prinzipiell ähnliche Wirkungen entfalten. Dennoch unterscheiden sich die einzelnen Substanzen mehr oder weniger stark in ihren pharmakodynamischen bzw. pharmakokinetischen Eigenschaften.
Die Pharmazeutische Betreuung von Patienten mit Hypertonie: Was ist beim Einsatz von Beta‐Adrenozeptorenblockern zu beachten?
Authors: Diers Karsten
Published: October 2004

Patienten mit hohem Blutdruck, die häufig mit β‐Blockern behandelt werden, sind trotz guter medikamentöser Therapiemöglichkeiten in einer Vielzahl von Fällen inadäquat eingestellt und erreichen die geforderten Blutdruckzielwerte von 140/90 mm Hg nicht. Als Grund hierfür kann neben dem fehlenden Leidensdruck der Patienten, der eine Krankheits‐ und Therapieeinsicht nachhaltig erschwert, die Angst vor Neben‐ und Wechselwirkungen bzw. deren reales Auftreten festgehalten werden. Dabei haben neuere Studien zeigen können, dass kardioselektive β‐Blocker oder solche mit vasodilatierenden Zusatzeigenschaften die für unselektive Pharmaka üblichen unerwünschten Wirkungen in weitaus geringerem Maße zeigen und bei entsprechenden Kontrollen auch bei obstruktiven Atemwegserkrankungen und bei Diabetikern eingesetzt werden können. Häufige Peak‐Flow‐ bzw. Blutzuckermessungen sowie die Dokumentation der Gesamtmedikation kann im Rahmen einen sinnvollen Beitrag zum Abbau der genannten Ängste und zur Verbesserung der Therapietreue der Betreuung solcher Patienten leisten und helfen unerwünschte Ereignisse so gering wie möglich zu halten.
Vioxx® und die anderen Coxibe
Authors: Steinbilber Dieter , Laufer Stefan
Published: October 2004

Am 30. September 2004 wurde der selektive Cyclooxygenase (COX)‐2‐Hemmer Rofecoxib (Vioxx®) vom Markt genommen. Das Präparat wurde in Deutschland von MSD vermarktet und erzielte weltweit einen jährlichen Umsatz von 2 Milliarden EURO.
Melt rheological behavior of starch‐based matrix composites reinforced with short sisal fibers
Authors: Alvarez V. A. , Terenzi A. , Kenny J. M. , Vázquez A.
Published: October 2004

A systematic analysis of the melt rheological behavior of a commercial starch‐based (MaterBi®) matrix composite reinforced with short sisal fibers is presented. The effects of shear rate, temperature, fiber content and treatment were analyzed by parallel‐plate rheometry, and classical non‐Newtonian models were applied to analyze the pseudoplasticity behavior of the molten composite systems. It is reported that shear rate is the most influential processing condition, while, from the point of view of the material structure, the intercalation effectiveness of the matrix in the fibers is directly linked to the rheological behavior. In fact, processing techniques with high stresses and more efficient mechanical mixing promote the opening of fiber bundles, increasing the aspect ratio of the fibers and the average viscosity of the molten composite. A similar effect on the increase of the aspect ratio and composite viscosity is observed when treated fibers are used. Polym. Eng. Sci. 44:1907–1914, 2004. © 2004 Society of Plastics Engineers.
Measurement and prediction of diffusion coefficients of supercritical CO2in molten polymers
Authors: Areerat Surat , Funami Eita , Hayata Yusuke , Nakagawa Dai , Ohshima Masahiro
Published: October 2004

The solubility and diffusivity of supercritical carbon dioxide (sc‐CO2) in low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polypropylene (PP), ethylene‐ethylacrylate copolymer (EEA) and polystyrene (PS) were measured at temperatures from 150°C to 200°C and pressures up to 12 MPa by using the Magnetic Suspension Balance (MSB), a gravimetric technique for gas sorption measurements. The solubility of CO2in each polymer was expressed by Henry's constant. The interaction parameter between CO2and polymer could be obtained from the solubility data, and it was used to estimate the Pressure‐Volume‐Temperature relationship and the specific free volume of polymer/CO2mixtures. The diffusion coefficients were also measured by the MSB for each polymer. The resulting diffusion coefficients were correlated with the estimated free volume of polymer/CO2mixture. Combining Fujita's and Maeda and Paul's diffusion models, a model was newly developed in order to predict diffusion coefficients for the polymers studied. Polym. Eng. Sci. 44:1915–1924, 2004. © 2004 Society of Plastics Engineers.
A temperature‐dependent adaptive controller. Part II: Design and implementation
Authors: Dubay Rickey , Lakhram Rodney
Published: October 2004

A generic online temperature‐dependent adaptive control procedure to redefine the controller parameters was developed from dynamic models to achieve good tracking of injection‐velocity setpoint profiles during filling of a mold cavity. This adaptive control procedure (ACP) incorporates algorithms for process open‐loop testing and modeling, control simulations, and online controller updating. These functionalities are embedded into a main program that provides overall control of mold‐filling velocity. The controller's dynamic matrix is updated as changes in the setpoint melt temperature occur. It was shown that the ACP can provide an effective and systematic approach for controlling injection mold‐filling velocity for any plastic material over its operating melt temperature range. Polym. Eng. Sci. 44:1934–1940, 2004. © 2004 Society of Plastics Engineers.
Rheology and processing of BaSO4‐filled medical‐grade thermoplastic polyurethane
Authors: Lu Guangyu , Kalyon Dilhan M. , Yilgör Iskender , Yilgör Emel
Published: October 2004

The rheological and processing behavior of BaSO4‐fllled medical‐grade (additive‐free) thermoplastic polyurethanes (TPUs) was investigated. The rheology and the single‐screw and twin‐screw extrusion processing of filled TPU were found to be complicated by the moisture and the air entrained into the suspension upon the incorporation of the filler BaSO4. It was observed that the 20 vol% BaSO4‐filled TPU exhibits decreased, rather than increased, shear viscosity and elasticity (as manifested through smaller storage modulus values in small‐amplitude oscillatory shear flow) in comparison to unfilled TPU in the temperature range of 190°C to 200°C at which these materials are usually processed. The moisture remaining in the BaSO4 will hydrolyze the polymer, leading to a decrease in the molecular weight of the TPU. However, the moisture contained in the filler itself is not sufficient to explain the significant reductions in viscosity and elasticity of the suspension upon the compounding of the BaSO4. It is shown that the major factor giving rise to the reductions in elasticity and the viscosity of the suspension of TPU and BaSO4 is the air (and the moisture air contains) entrained into the extruder during the feeding of the BaSO4. Air, carried with the filler into the extruder, is entrained into the suspension to hydrolyze the TPU and to further impart a foamy structure under typical processing conditions to significantly reduce the shear viscosity and the elasticity of the suspension in comparison to unfilled TPU. Polym. Eng. Sci. 44:1941–1948, 2004. © 2004 Society of Plastics Engineers.
Runner balancing by a direct genetic optimization of shrinkage
Authors: Alam Kevin , Kamal Musa R.
Published: October 2004

The proposed approach to the runner‐balancing problem evaluates differences in shrinkage among the cavities and uses this direct measure of product quality to balance runner systems instead of the indirect methods traditionally used. The runner‐balancing problem was characterized by multiple objectives, which consider both cost and product quality. The resulting multi‐objective optimization problem was solved with a multi‐objective genetic algorithm. Runner‐balancing optimizations varied the diameters and lengths of the runners and the processing conditions. The results suggest that balanced runner systems, which exhibit large differences in cavity pressure profiles, can have lower product costs than systems characterized by similar fill times and cavity pressure profiles. The optimization of the secondary runner lengths and processing conditions also reduced costs significantly. Polym. Eng. Sci. 44:1949–1959, 2004. © 2004 Society of Plastics Engineers.
The effects of polymer additives on the operating windows of slot coating
Authors: Yang C. K. , Wong D. S. H. , Liu T. J.
Published: October 2004

An experimental study was carried out to investigate the effects of polymer additives on the operating windows of slot coating. Two polymer additives—carboxylmethylcellolose (CMC) and polyacrylamide (PAA)—were added to Newtonian glycerin solutions as test fluids. The flow experiment was performed on a lab coater. A flow visualization technique was employed to observe the shapes of coating beads. It was found that three types of defects appear at the lower bound of the operating window, i.e., ribbing, air entrainment, and break lines coupled with dripping. Adding a small amount of polymer additives has little effect on the operating window if the defect is ribbing, but it will expand the air entrainment region. The coating speed can be increased significantly if the defect is break lines coupled with dripping. Polym. Eng. Sci. 44:1970–1976, 2004. © 2004 Society of Plastics Engineers.
Nernst–Ettingshausen and magnetoresistance effects in Hg1–xCdxSe single crystals in vicinity of phase transitions under hydrostatic pressure
Authors: Shchennikov Vladimir V. , Ovsyannikov Sergey V.
Published: October 2004

In the present paper the thermomagnetic longitudinal and transverse Nernst–Ettingshausen (N–E) effects were investigated in Hg1–xCdxSe (x = 0.03, 0.07) single crystals at hydrostatic pressure up to ∼2 GPa. Substitution of Cd atoms into cation sublattice increases strongly the stability of initial zinc blende lattice and shifts the phase transformation into cinnabar structure to higher pressures P ≥ 1.4 GPa. For ternary Hg1–xCdxSe compounds the values of mobility and scattering parameters of charge carriers have been obtained from the N–E and magnetoresistance (MR) effects up to phase transition points 1.4–1.7 GPa. The decreasing of mobility under pressure is consistent with opening of direct semiconductor gap. In vicinity of the structural phase transformations into cinnabar structure an anomaly of transverse N–E effect was observed connected probably with peculiarity of electronic band structure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Observation of localization effects in InGaN/GaN quantum structures by means of the application of hydrostatic pressure
Authors: Franssen G. , Kamińska A. , Suski T. , Suchocki A. , Kazlauskas K. , Tamulaitis G. , Žukauskas A. , Czernecki R. , Teisseyre H. , Perlin P. , Leszczyński M. , Boćkowski M. , Grzegory I. , Grandjean N.
Published: October 2004

Localization phenomena related to the fluctuating band potential profile of the InGaN alloy were investigated via hydrostatic pressure dependent measurements of luminescence of an InGaN quantum structure. We examine the suitability of the hydrostatic pressure coefficient as a tool for evaluation of the degree of localization of recombining carriers in the InGaN alloy. This is done by experimental investigation of the correlation between the pressure coefficient of the luminescence peak and the Stokes shift between luminescence and the absorption edge, which constitutes a measure of the degree of localization of recombining carriers in the InGaN alloy. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Semiconductor–metal transitions in low‐Z and alkali fluids
Authors: Nellis W. J.
Published: October 2004

Experiments are described which observed semiconductor‐metal Mott transitions in fluid H, N, O, Rb, and Cs at ∼2000 K. The pressures required to observe this transition in low‐Z and in alkali fluids differ by a factor of 104. This difference in pressure is caused by differences in radial extents of charge density distributions of the respective atoms. Dynamic pressures and temperatures can now be tuned to probe states not accessible previously to scientific investigation. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure dependence of phonon modes in CdGeP2
Authors: Choi In‐Hwan , Yu Peter Y.
Published: October 2004

The Raman spectra of a single crystal of CdGeP2 have been measured as a function of pressure using a tunable infrared Ti:sapphire laser and a diamond anvil high pressure cell. The pressure coefficients of the zone‐center optical phonons have been determined. The results are compared with those of the corresponding zincblende‐type (GaP and InP) and I–III–VI2 chalcopyrite (AgGaS2) compounds. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recombination dynamics in self‐assembled InP/GaP quantum dots under high pressure
Authors: Kristukat C. , Dworzak M. , Gonñi A. R. , Zimmer P. , Hatami F. , Dreßler S. , Hoffmann A. , Masselink W. T. , Thomsen C.
Published: October 2004

We have investigated the recombination dynamics in self‐assembled InP/GaP quantum dots by means of time‐resolved photoluminescence measured at low temperatures between 2 and 100 K and high hydrostatic pressure up to 2 GPa. Due to the high‐power levels for pulsed excitation, the quantum dot emission exhibits two components with typical decay times of 5 and 30 ns, corresponding to direct Γ– Γ and X– Γ interband recombination processes, respectively. These decay times appear to be independent of pressure. At a very low pressure of about 0.1 GPa the intensity of the dot emission drops abruptly relative to that of the wetting layer indicating a switching off of a carrier relaxation channel. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐pressure properties of icosahedron‐based solid borons
Authors: Shirai Koun , Masago Akira , Katayama‐Yoshida Hiroshi
Published: October 2004

High‐pressure experiments have led to significant contributions to understanding of physical properties of icosahedron‐based solid boron. In this paper, we critically review recent results on properties of boron polytypes. The topics discussed are stability of α‐ and β‐boron, elastic properties, phonon properties. In interpreting high‐pressure experiments, special care is needed. In many cases, confusion is emerged from difference between the macroscopic applied deformation and the resulting microscopic displacement of atoms. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure‐Raman study of resonant TO(Γ)–two‐phonon decay processes in ZnS: Comparison of three isotope compositions
Authors: Tallman R. E. , Serrano J. , Cantarero A. , Garro N. , Lauck R. , Ritter T. M. , Weinstein B. A. , Cardona M.
Published: October 2004

Pressure‐Raman studies (to 15 GPa, at 300 K and 16 K) are reported on 64Zn34S, 68Zn32S, and natural ZnS to compare the effects of resonant 3‐phonon mixing on the TO(Γ) phonons for the different isotope compositions. Under pressure the TO(Γ) Raman profiles exhibit several distinct features, and a sharp Lorentzian TO(Γ) peak eventually emerges at a threshold pressure PTh that differs for each isotope composition. These effects are due to resonant mixing of the TO(Γ) phonon with TA + LA combination modes. Calculations based on a bond‐charge model and perturbation theory reproduce the observed pressure variations in the shape and the width of the TO(Γ) peaks. It is shown that these changes relate to singularities in the TA + LA density of states. Mass scaling of the TO(Γ) and TA + LA modes explains the isotope effect on PTh, and leads to the estimate γLA(W) ∼1.2. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Femtosecond pump and probe spectroscopy in Bi under high pressure
Authors: Kasami M. , Mishina T. , Nakahara J.
Published: October 2004

We have observed coherent phonons and electronic response in bismuth single crystals under hydrostatic pressure up to 3 GPa at room temperature. Both signals show drastic changes at 2.5 GPa where phase transition occurs. The phonon frequency decreases from 2.9 THz to 2.5 THz and the initial phase of the phonon shifts about 180 degrees at this pressure. The electronic response shows anomalous behaviour above phase transition pressure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure‐dependent photoluminescence study of CuGaSe2
Authors: Shan W. , Walukiewicz W. , Wu J. , Yu K. M. , Ager J. W. , Siebentritt S. , Rega N.
Published: October 2004

We present the results of a pressure‐dependent photoluminescence (PL) study on CuGaSe2 films grown on GaAs substrate by metalorganic vapor phase epitaxy. The low‐temperature PL spectra of the CuGaSe2 samples measured at atmospheric pressure are dominated by one near band edge exciton luminescence line and two strong and relatively broad emissions associated with donor acceptor pairs (DAP) transitions. All the observed luminescence emission lines shift toward higher energy with increasing pressure at the same rate. The nearly identical pressure coefficients of the two DAP emissions as compared to that of the exciton emission confirm the suggestion that the recombination processes associated with the DAPs involve one shallow effective‐mass donor and two different acceptor species with different binding energies and related to two different native defects. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symmetric and asymmetric GaAs/Al0.3Ga0.7As double quantum well subjected to hydrostatic pressure and applied electric field
Authors: Morales A. L. , Raigoza N. , Montes A. , Porras‐Montenegro N. , Duque C. A.
Published: October 2004

The combined electric field and hydrostatic pressure effects on the binding energy of a shallow‐donor impurity in symmetrical and asymmetrical GaAs/Al0.3Ga0.7As double quantum wells are calculated using a variational procedure within the effective‐mass approximation. Double quantum wells are examinated considering impurities situated at the well centers. Due to the applied electric field both structures become asymmetric from the impurity potential point of view. According to the dimensions the structures are symmetric (equal well lengths) and asymmetrical (different well lengths). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High pressure Raman study of Y3Al5O12
Authors: Arvanitidis J. , Papagelis K. , Christofilos D. , Kimura H. , Kourouklis G. A. , Ves S.
Published: October 2004

The effect of high hydrostatic pressure on Y3Al5O12 (YAG) single crystals has been studied up to 15 GPa by Raman spectroscopy at room temperature. The pressure dependence of 23 Raman‐active modes, out of 25 predicted by group theory, has been followed. The determined mode Grüneisen parameters (γi) extend over a relatively narrow range (0.6–2.4) indicating binding forces of the same nature and order of magnitude. However, the modes in the high (650–900 cm–1) and middle (500–600 cm–1) regions of the Raman spectrum exhibit γi parameter values ranging between 0.9–1.4 and 0.7–0.8, respectively; reflecting that different type of AlO4 molecular vibrations and consequently different kind of restoring forces being involved in these modes, in accordance with theoretical predictions. The strength of interactions in YAG along with the high compactness of the garnet structure explains, somehow, their high stability upon pressure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High pressure as a tool to tune electronic coupling in self‐assembled quantum dot nanostructures
Authors: Rybchenko S. I. , Itskevich I. E. , Andreev A. D. , Cahill J. , Tartakovskii A. I. , Skolnick M. S. , Hill G. , Hopkinson M.
Published: October 2004

High pressure provides an efficient way of controlling the electronic properties of semiconductor nanostructures. We use pressure to tune electronic coupling in stacks of self‐assembled quantum dots (SAQDs). The coupling occurs as soon as the distance and the height of the barriers between the dots are sufficiently small to permit interaction between the wavefunctions of electrons in adjacent dots. We demonstrate experimental evidence that application of pressure reduces and may quench the coupling. This happens because, under pressure, the inter‐dot barriers become higher and hence less transparent for electron wavefunctions. The effect was revealed by means of photoluminescence spectroscopy and confirmed by theoretical modelling. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural phase transition in lanthanum monochalcogenides induced by hydrostatic pressure
Authors: Varshney Dinesh , Kaurav N. , Sharma P. , Shah S. , Singh R. K.
Published: October 2004

An effective interionic interaction potential (EIOP) is developed to investigate the pressure induced phase transitions from NaCl‐type (B1) to CsCl‐type (B2) structure in lanthanum monochalcogenides LaX [X = S, Se, Te] compounds. The long range Coulomb, van der Waals (vdW) interaction and the short‐range repulsive interaction up to second‐neighbor ions within the Hafemeister and Flygare approach with modified ionic charge are properly incorporated in EIOP. The vdW coefficients are computed following the Slater–Kirkwood variational method, as both the ions are polarizable. The estimated value of the phase transition pressure (Pt) and the magnitude of the discontinuity in volume at the transition pressure are consistent with the reported data. A large volume discontinuity in the pressure‐volume phase diagram identifies the structural phase transition from B1 to B2 structure. We also study the second order elastic constants for these La compounds. It appears that the vdW interaction is effective in determining the elastic and structural properties of these test compounds. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐pressure thermopower of PbTe‐based compounds
Authors: Ovsyannikov Sergey V. , Shchennikov Vladimir V.
Published: October 2004

In the present paper the thermoelectric properties of p‐type PbTe‐based compounds (Pb1–xGaxTe, Pb1–xSnxTe, Pb1–xSixTe, Pb1–xMnxTe, PbTe1–y, Pb1–yTe) have been investigated at high pressure up to ∼12 GPa. Structural phase transitions from cubic NaCl into orthorhombic GeS structure have been observed with thermoelectric measurements. A low sensitivity of thermoelectric properties to high‐pressure treatment has been found for PbSnTe compounds (x ≈ 0.29). For the rest of the samples with a small content of doping atoms a sign inversion and a following maximum of thermoelectric power S have been established at pressures ∼1–3 GPa. The results obtained show the possibility of improving the thermoelectric figure of merit and effectiveness at moderate pressures for PbTe‐based compounds. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations of multiphase states in vicinity of pressure‐induced phase transitions
Authors: Shchennikov Vladimir V. , Ovsyannikov Sergey V. , Vorontsov Grigoriy V. , Shchennikov Vsevolod V.
Published: October 2004

In the present work equations have been derived for thermomagnetic and galvanomagnetic effects of multiphase systems. The equations allow us to analyse complex thermal–electrical–magnetic properties of semiconductors under variation of concentration and configuration of inclusions. The results obtained make it possible, for example, to explain discrepancies between values of phase‐transition pressure determined from thermal, electrical, volumetric and other effects. A model developed has been applied for analysis of semiconductor–metal phase transitions. The approach offered allows us also to search for ways for improvement of thermoelectric and thermomagnetic effectiveness and figure of merit of complex semiconductor systems. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bronchoplastic procedures for lung cancer: Clinical study in 136 patients
Authors: Kawahara Katsunobu , Akamine Shinji , Tsuji Hiroharu , Nakamura Akihiro , Takahashi Takao , Tagawa Yutaka , Ayabe Hiroyoshi , Tomita Masao
Published: October 2004

Between 1969 and 1991 a total of 136 patients (119 men, 17 women) underwent bronchoplastic procedures for lung cancer. A bronchoplastic procedure with angioplasty was performed in 37 patients. Ages ranged from 30 to 79 years (mean 62 years). The histologic type of cancer was squamous cell carcinoma in 97 patients (70.0%). The 30‐day mortality was 5.1% (7 patients), and morbidity was 30.1% (41 patients). The most common complications were bronchopleural fistula in nine (6.6%), stricture or stenosis in eight (5.9%) and atelectasis in eight patients. Local recurrence occurred in nine (6.6%) patients. The overall 5‐year survival for patients undergoing bronchoplastic procedures was 37.1%: 60.1% for patients with stage I disease (n=41), 31.7% for stage II (n=17), and 29.7% for stage IIIA (n=66). We conclude that bronchoplastic procedures are effective therapy for selected patients with lung cancer.
Association of immunohistochemical p53 tumor suppressor gene protein overexpression with prognosis in highly proliferative human mammary adenocarcinomas
Authors: Schimmelpenning Hendrik , Eriksson Elina T. , Zetterberg Anders , Auer Gert U.
Published: October 2004

An increasing body of evidence suggests that in addition to conventional histopathologic tumor characteristics, DNA content measurements, cell kinetic data, and investigatios of tumor suppressor gene expressions might be of valuable information in breast cancer patients. Against this background we investigated immunohistochemically overexpression of the interphase associated protein proliferating cell nuclear antigen (PCNA) and the mutant p53 protein in routinely paraffin‐embedded surgical specimens from 180 breast cancer patients with known nuclear DNA profiles. The mean clinical follow‐up was 16 years (range 13–20 years). The percentage of PCNA immunoreactive tumor cell nuclei ranged between <5% and 60% (mean 13.59±10.85%). There was a direct association between high levels of PCNA expression (>20%) and p53 protein overexpression (p=0.019). Mutant p53 protein overexpression was found in 44 of 180 (24%) cases and was significantly related to high histologic tumor grade (p=0.004), DNA aneuploidy (p=0.001), and high levels of PCNA expression (p=0.001). Patients with highly proliferative carcinomas (>20% PCNA expression) had a shortened distant metastases‐free survival when their neoplasms overexpressed p53. In contrast, the distant metastases‐free survival of patients with highly proliferative, p53‐negative tumors was significantly longer (p=0.03). Immunohistochemical p53 protein overexpression thus appears to be indicative of an increased malignant potential in breast cancer patients. Highly proliferative tumors composed of p53 immunoreactive neoplastic cells clinically seem to behave more aggressively than the highly proliferative p53‐negative tumors.
Curative surgery for gastric cancer: Study of 166 consecutive patients
Authors: Mendes de Almeida J. C. , Bettencourt A. , Santos Costa C. , Mendes de Almeida J. M.
Published: October 2004

From January 1980 to December 1991 we operated on 295 patients with a gastric carcinoma. In 166 cases (56.3%) surgery was performed with curative intent. In 93 patients (56%) a subtotal gastrectomy was performed, and in 73 cases (44%) a total gastrectomy. In all the cases a D‐2 type lymphadenectomy was used. The global morbidity rate was 23%, and in‐hospital mortality was 3.6%. The morbidity and mortality rates of these two operations were statistically different. Global 5‐year survival estimate for the whole series is 61.3%. Univariate and multivariate analysis according to T and N (TNM classification), the number of positive nodes resected, and the relation of positive per resected nodes, revealed statistically different outcomes. This kind of quantitative classification allowed identification of high risk groups irrespective of site of nodal involvement. Tumors classified as intestinal or diffuse type by the Lauren classification had similar survival curves and 5‐year survival estimates (p=0.834). By univariate and multivariate analysis this classification did not reveal a prognostic value in this group of patients. In our opinion, tumor penetration and lymph node involvement are at present the most reliable prognostic factors available.
Selective decontamination of the colon before elective colorectal surgery
Authors: Taylor T. W. , Lindsay G. ,   West of Scotland Surgical Infection Study Group
Published: October 2004

The controversy over the route of administration of antibiotic prophylaxis in patients undergoing elective colorectal operations persists for oral, parenteral, and a combination of the two routes. The oral antibiotics commonly administered for colorectal prophylaxis, neomycin and eythromycin base, are not absorbed in the gastrointestinal tract (GIT). However, the 4‐fluoroquinolones are absorbed in the upper GIT and are excreted in part by the colonic mucosa. Their action is then to remove, or severely depress, the gram‐negative aerobic bacilli leaving the anaerobic flora unaffected. This action is the principle of selective decontamination. We have assessed the efficacy of oral ciprofloxacin in a prospective randomized clinical trial in which all patients received piperacillin 4 g IV as single‐dose parenteral prophylaxis. A group of 327 evaluable patients were randomized to receive ciprofloxacin 500 mg b.i.d. with the preoperative cathartic (group OA,n=159) or no oral antibiotic (11.3%) patients in group OA and 39 (23.2%) patients in group NOA (χ2= 7.2,p=0.007). Operation‐related infection of any type occurred in 23 (14.5%) patients in group OA compared with 55 (32.7%) in group NOA (χ2= 14.0,p=0.0002). The median postoperative hospital stay was 11 days (interquartile range 4.5 days) for group OA and 12 days (interquartile range 8 days) for group NOA (Mann Whitney U test,p=0.005). Ignoring the treatment group, the median postoperative hospital stay was 17 days (interquartile range 10 days) for infected patients and 11 days (interquartile range 4 days) for those not infected. We conclude that the administration of ciprofloxacin 500 mg b.i.d. with the preoperative cathartic significantly reduces the incidence of infection after elective colorectal operations and should form part of the preoperative preparation for such operations.
Adjunctive antimicrobial therapy for complicated appendicitis: Bacterial overkill by combination therapy
Authors: Hopkins Judith A. , Wilson Samuel E. , Bobey David G.
Published: October 2004

Although single antimicrobials with broad‐spectrum aerobic and anaerobic coverage are effective in patients with appendicitis, many general surgeons continue to use multiple agents. A prospective, doubleblind, randomized trial was designed to detect any clinical correlate of in vitro susceptibility advantage of multiple antimicrobials as adjunctive therapy for 114 patients undergoing operation for complicated appendicitis. There was clinical resolution of intraabdominal infections with no occurrence of postoperative infectious complications in 90% (36 of 40) of the cefotetan group and 86% (31 of 36) of the clindamycin/amikacin group (p=0.11). The number of patients who had changes in antibiotic therapy due to postoperative complications was higher in the clindamycin/amikacin group: five (12.5%), compared to one (2.8%) in the cefotetan group (p=0.07). Although Bacteroides fragilis group organisms resistant to cefotetan were identified, none was responsible for the postoperative infections. Adverse drug events in 28% of the cefotetan group and 26% of the clindamycin/amikacin group consisted primarily of transient elevations of liver function tests. Monotherapy with a second‐generation, broad‐spectrum cephalosporin, such as cefotetan, given twice a day is an economical and effective adjunctive regimen in patients with complicated appendicitis for which operation is the definitive treatment. Aminoglycosides and other, more potent antimicrobials should be reserved for resistant organisms or nosocomial infections.
Badger culling does not control cattle TB
Authors: HANCOX M.
Published: October 2004

A somewhat unpredicted effect of the 2001 Foot and Mouth crisis, has been to ‘derail the TB control programme both as regards cattle measures and the badger culling trial’ (EFRA 2003). Sadly, cattle TB is now out of control, rising by c. 20% a year, and back to 1960s levels. Unfortunately attention has focused to such an extent on badgers that many now seemingly do not understand how TB works in cattle and why annual testing and movement bans are the answer: they brought cattle TB down to tiny southwest hot-spots by the mid-1970s without any badger culling (Hancox 2000, 2002, 2003).
Nitrate leaching and N2-fixation in grasslands of different composition, age and management
Authors: ERIKSEN J. , VINTHER F. P. , SØEGAARD K.
Published: October 2004

Grass-legume associations may offer a way of improving the N efficiency of dairy farming, but may also have an adverse impact on the environment by increasing leaching losses. Nitrate leaching from four cropping sequences with different grassland frequency and management (long-term grazed, long-term cut, cereals followed by 1 and 2-year grazed leys) were investigated on a loamy sand in central Jutland for both unfertilized grass-clover (perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.)) and fertilized perennial ryegrass (300 kg N/ha) swards during 1997–2002. Furthermore, 1 year (2001) of N2 fixation in 1-, 2- and 8-year-old grass-clover pastures was determined. Nitrate leaching from grazed unfertilized grass-clover was always considerably lower than from grazed fertilized ryegrass. The effect of grassland age on nitrate leaching was insignificant in grass-clover but clear in grazed ryegrass, where levels increased dramatically with sward age. In production years 6–8, leaching from grass-clover was only 9–13% of the comparable losses from ryegrass. Under the cutting regime grass-clover showed a significant reduction in both yield and N-removal with increasing sward age, whereas for ryegrass these figures did not show any decreasing trend. N2 fixation was lower in 8-year-old swards compared with fully established 2-year-old swards as a consequence of lower dry matter production, lower clover content and a lower proportion of clover-N derived from the atmosphere. The results from the present study indicate that the higher leaching losses observed in fertilized grass compared with unfertilized grass-clover systems were caused by (1) a reduction in N2-fixation in grass-clover over time and (2) a reduction in dry matter production in grass-clover over time, lowering the grazing intensity and the recycling of grassland N via animal excreta.
Effect of variable intake of alfalfa and wheat on faecal alkane recoveries and estimates of roughage intake in sheep
Authors: ELWERT C. , KLUTH H. , RODEHUTSCORD M.
Published: October 2004

The alkane technique allows estimates of intake and diet composition. For the latter a correction for incomplete recovery of faecal alkane concentrations has to be made. Feeding level and diet proportions have been discussed as factors possibly influencing recovery. A balance trial was conducted to study these effects on faecal alkane recovery rates and their consequences on estimates of roughage intake in sheep. The diets consisted of force-dried pelleted alfalfa meal (A) and wheat whole meal (W) in three levels each (360, 480, 600 and 270, 360, 450 g/day, respectively); the wheat was partly labelled with beeswax to provide a distinctive alkane pattern. Each diet was fed to four wethers. Despite significant effects (P<0·05) of A and W on organic matter digestibility, no such effects were observed for alkane recovery rates. Estimates of alfalfa intake were better if alkanes with a higher coefficient of variation of recovery were not included in diet composition estimates. Furthermore, in spite of the lack of significance of the dietary factors A, W and A×W, faecal alkane concentration correction based upon diet-specific faecal recoveries gave better estimates of alfalfa intake than based on overall recoveries. The estimate of alfalfa intake differed from known intake by −1·7 to −2·6%, depending on the method of estimation. The relative mean discrepancy was regarded as a tool to assess estimated intakes of individual animals. It ranged from 4·4 to 14·2% for dietary treatments and was 7·6% for all animals. The poor quality of estimates for individual animals may result from the variation of faecal recovery rates and needs further investigation.
Some changes in grass crops during periods of uninterrupted growth
Authors: WILMAN D.
Published: October 2004

In order to make informed decisions about the timing of harvests of grass crops, it is helpful to be aware of the changes that are taking place in the crops as they grow. Most people growing grass commercially or experimentally have a general awareness of the more obvious changes. However, greater awareness and understanding should lead to greater precision and greater success in the relevant enterprises. The present review considers some of the more important changes that are of interest from an agricultural point of view and for which sufficient information is available in the scientific literature. It is intended for relevant students, lecturers, research workers, advisers and producers.
Use of covariance structures for temporal errors in the analysis of a three-course wheat rotation and tillage trial
Authors: SINGH M. , PALA M.
Published: October 2004

Crop rotation serves as a mechanism for developing sustainable crop production systems. Crop-rotation trials are used to identify agronomic input factors suitable for use in a cropping system. In crop-rotation trials, experimental errors within the same plot over time are correlated. The form of the covariance structure of the plot errors may be specific to the data from a rotation trial, but is unknown and is generally assumed. Statistical analyses are usually based on the assumption that plot errors are independent, or have constant covariance. An experiment was conducted using wheat-based, three-course rotations containing tillage treatment subplots over 12 years at ICARDA's experimental station at Tel Hadya, a moderately dry area in northern Syria. This study examined several covariance structures for temporal errors arising over the rotation plots and tillage subplots, in order to model wheat yield data. Eighteen covariance structures were examined, and the best pair was selected using the Akaike Information Criterion. The best pair comprised first-order autocorrelation and homogeneous variance for temporal errors in rotation plots, and uniform correlation with heterogeneous variances for temporal errors in tillage subplots. Using the 12 years of data obtained for wheat yield and the best pair of covariance structures, the tillage and rotation effects were found to be statistically significant and to have significant interactions with the cycle of rotation. The precision of the means calculated differed from those calculated using a control structure based on homogeneous error variances and constant correlation. The cumulative yield build-up over time differed significantly over the rotations and the tillage methods. An increasing yield trend was observed for the bread wheat rotation, while a yield decline was observed in durum wheat when the rotation was repeated. When evaluating the effects of input factors in crop rotations, we therefore recommend that the covariance structures be examined and that a suitably chosen structure be used.