bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission Fluctuation Spectrometry with Spatial Correlation
Authors: Shen Jianqi , Riebel Ulrich , Guo Xiaoai
Published: June 2005

Transmission fluctuation spectrometry (TFS) is being developed as a new method of particle size analysis. In the early approaches, the particle suspension was illuminated by one beam with finite beam diameter and the transmission signals underwent a process with variable spatial and/or temporal averaging and a subsequent nonlinear operation. The transmission fluctuations were obtained as a spectrum which included the information on particle size distribution and particle concentration.

A new approach presented here employs two narrow parallel beams. While changing the beam separation, the transmission fluctuations of these two beams are expressed in terms of the expectancy of the transmission product (ETP). The analytical expression of the ETP through a monolayer is derived and the ETP of a 3‐dimensional suspension is formulated based on the layer model. The deviation between the transition functions of 3‐dimensional suspensions and monolayers is found to be affected by effects from particle overlapping and monolayer structure.
Statistical Analysis of Pellet Size Variation in Commercial Catalysts
Authors: Wu Dongfang , Zhou Jiancheng , Li Yongdan
Published: June 2005

The size of commercial catalyst pellets is distributed over a range of values. The suitability of the normal, lognormal and Weibull distributions to model pellet size variation was judged by three quality‐of‐fit criteria: the coefficient of determination, Akaike information criterion and Kolmogorov‐Smirnov test, respectively. It is concluded that the normal distribution is most appropriate to represent the diameter distribution of the spherical pellets, though the lognormal distribution also gives a satisfactory fit. The Weibull distribution is the best one to represent the length distribution of the catalyst tablets. It is elucidated that a downward tail of the tablet length distribution results from the fluctuating characteristics of feeding for the individual tablets. It is also pointed out that pellet size distributed in a narrow window is beneficial to the industrial application of solid catalysts.
Various strategies of using residual dipolar couplings in NMR‐driven protein docking: Application to Lys48‐linked di‐ubiquitin and validation against 15N‐relaxation data
Authors: van Dijk Aalt D.J. , Fushman David , Bonvin Alexandre M.J.J.
Published: June 2005

When classical, Nuclear Overhauser Effect (NOE)‐based approaches fail, it is possible, given high‐resolution structures of the free molecules, to model the structure of a complex in solution based solely on chemical shift perturbation (CSP) data in combination with orientational restraints from residual dipolar couplings (RDCs) when available. RDCs can be incorporated into the docking following various strategies: as direct restraints and/or as intermolecular intervector projection angle restraints (Meiler et al., J Biomol NMR 2000;16:245–252). The advantage of the latter for docking is that they directly define the relative orientation of the molecules. A combined protocol in which RDCs are first introduced as intervector projection angle restraints and at a later stage as direct restraints is shown here to give the best performance. This approach, implemented in our information‐driven docking approach HADDOCK (Dominguez et al., J Am Chem Soc 2003;125:1731–1737), is used to determine the solution structure of the Lys48‐linked di‐ubiquitin, for which chemical shift mapping, RDCs, and 15N‐relaxation data have been previously obtained (Varadan et al., J Mol Biol 2002;324:637–647). The resulting structures, derived from CSP and RDC data, are cross‐validated using 15N‐relaxation data. The solution structure differs from the crystal structure by a 20° rotation of the two ubiquitin units relative to each other. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Comparing protein–ligand docking programs is difficult
Authors: Cole Jason C. , Murray Christopher W. , Nissink J. Willem M. , Taylor Richard D. , Taylor Robin
Published: June 2005

There is currently great interest in comparing protein–ligand docking programs. A review of recent comparisons shows that it is difficult to draw conclusions of general applicability. Statistical hypothesis testing is required to ensure that differences in pose‐prediction success rates and enrichment rates are significant. Numerical measures such as root‐mean‐square deviation need careful interpretation and may profitably be supplemented by interaction‐based measures and visual inspection of dockings. Test sets must be of appropriate diversity and of good experimental reliability. The effects of crystal‐packing interactions may be important. The method used for generating starting ligand geometries and positions may have an appreciable effect on docking results. For fair comparison, programs must be given search problems of equal complexity (e.g. binding‐site regions of the same size) and approximately equal time in which to solve them. Comparisons based on rescoring require local optimization of the ligand in the space of the new objective function. Re‐implementations of published scoring functions may give significantly different results from the originals. Ostensibly minor details in methodology may have a profound influence on headline success rates. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Structural and immunological reactivity of the principal neutralizing determinant V3 of glycoprotein gp 120 of HIV‐1
Authors: Borbe Harald C. , Stuber György , Wagner Ralf , Wolf Hans , Modrow Susanne
Published: May 2005

The variable domain V3 in the outer glycoprotein gp 120 of HIV‐1 is a highly important region with respect to immune response during the course of viral infection. Neutralizing antibodies are produced against this domain; in addition, it has been shown to be a functionally active epitope for T helper and cytotoxic T cells. The high degree of amino acid variability in individual HIV‐isolates, however, limits the use of the V3‐domain in approaches to vaccine development. In order to characterize the residues important for antibody interaction and binding to MHC class I proteins, we constructed a consensus sequence of the V3‐domain with broad reactivity [1] and used synthetic peptides derived from this consensus with individual residues altered to alanine. These peptides were used as antigens in ELISA tests to define the amino acids which are important for binding to human and rabbit/anti‐peptide immunoglobulins. In addition, we used these alanine‐derived peptides in interaction studies with human HLA‐A2.1 and mouse H‐2Dd by testing their capacity to stabilize the respective MHC class I protein complexes on the surface of mutant cell lines T2 and RMA‐S transfected with Dd gene. The experimental tests allowed us to define individual residues involved in antibody and MHC‐protein interaction, respectively. In a further approach, we used those results to design interaction models with HLA‐A2.1 and H‐2Dd. Therefore, a structural model for H‐2Dd was built that exhibits an overall similar conformation to the parental crystal structure of HLA‐A2.1. The resulting interaction models show V3‐peptide bound in an extended β‐conformation with a bulge in its centre for both H‐2Dd and HLA‐A2.1 complexes. The N‐ and C‐termini of V3 peptide reside in conserved pockets within both MHC‐proteins. Anchoring residues could be determined that are crucial for the binding of the respective MHC class I haplotype. The cross‐reactivity of V3‐peptide in enhancing the expression of two different MHC class I molecules (H‐2Dd and HLA‐A2.1) is shown to be based on similar peptide binding that induces an almost identical peptide conformation.
The use of N‐urethane‐protected N‐carboxyanhydrides (UNCAs) in amino acid and peptide synthesis
Authors: Fehrentz Jean‐Alain , Genu‐Dellac Corine , Amblard Muriel , Winternitz Franclois , Loffet Albert , Martinez Jean
Published: May 2005

N‐Urethane‐protected N‐carboxyanhydrides (UNCAs) are very reactives. They have been successfully used in peptide synthesis, in both solution and solid phase. We have demonstrated that UNCAs are interesting starting materials for the synthesis of various amino acid derivatives. Chemoselective reduction of UNCAs with sodium borohydride led the corresponding N‐protected β amino alcohols. Reaction of UNCAs with Meldrum's acid, followed by cyclisation, yielded enantiomerially pure tetramic acid derivatives. Diastereoselective reduction of tetramic acid derivatives produced (4S,5S)‐N‐alkoxycarbonyl‐4‐hydroxy‐5‐alkylpyrrolidin‐2‐ones derived from amino acids, which after hydrolysis yielded statine and statine analogues. Tetramic acid derivatives could also be obtained by reaction of UNCAs with benzyl ethyl followed by hydrogenolytic deprotection and decarboxylation. UNCAs also reacted with phosphoranes to produce the ketophosphorane in excellent yields. Subsequent oxidation with oxone or with [bis(acetoxy)‐iodol]‐benzene produced vicinal tricarbonyl derivatives. These reactions usually proceeded smoothly and with high yields.
Proteinogenic amino acids labelled with 15N and/or 13C for application in peptide synthesis: A short review with a comprehensive list of published derivatives
Authors: Ragnarsson Ulf
Published: May 2005

A review is given of the literature dealing with the most common protected derivatives of 15N‐ and/or 13C‐labelled amino acids of interest in peptide synthesis. The list contains all such Boc‐, Z‐ and Fmoc‐amino acids as well as published methyl, ethyl, t‐butyl and benzyl esters.
Synthesis and properties of the first all‐aza analogue of a biologically active peptide
Authors: Gante Joachim , Krug Michael , Lauterbach Günter , Weitzel Reinhard , Hiller W.
Published: May 2005

The synthesis of the first all‐aza‐amino acid analogue (2) of a peptidic renin inhibitor is described. The X‐ray structural analysis and molecular modelling investigations of this novel compound reveal interesting conformational features which have a significant impact on its biological activity. In addition, insight into conformational features of azapeptides in general in comparison with the corresponding purely peptidic compounds is given.
Solid‐phase Synthesis of ω‐Agatoxin IVA, a P‐type Calcium Channel Blocker
Authors: Najib Jamila , Letailleur Thierry , Gesquière Jean‐Claude , Tartar André
Published: May 2005

ω‐Agatoxin IVA, isolated from the venom of funnel web spider Agelenopsis aperta, blocks potently and selectively P‐type calcium channels. This toxin, composed of 48 amino acids and containing 8 cysteine residues, was synthesized by the solid‐phase procedure. The Cys residues were protected by acetamidomethyl (Acm) groups which were removed by mercuric acetate. During treatment with mercuric acetate, a by‐product was detected, involving modification of tryptophan residues by the Acm groups. This side reaction can be completely prevented by addition of an excess of tryptophan in the reaction medium during Acm deprotection.

The resulting peptide was submitted to an oxidative refolding, in different conditions, in order to determine the most favourable protocol. After formation of the four disulphide bonds, the toxin was purified by successive preparative HPLC, on two different supports, and fully characterized by analytical HPLC, capillary electrophoresis, amino acid analysis, mass spectrometry and Edman degradation. It was found to block the P‐type calcium channel with a similar biological potency as described for the natural product.
The Use of Proton Chemical Shifts to Define the Solution Structure of a Dimeric Peptide
Authors: Busetta Bernard , Picard Philippe
Published: May 2005

For flexible peptides, nuclear Overhauser Effects (NOE) experiments do not provide enough information to ensure a correct definition of their solution structure. The use of distance constraints, derived from the knowledge of proton chemical shifts, is developed to restrict the number of possible conformations. In the case of flexible molecules, randomization appears as an important factor of the correct estimation of the chemical shifts from the 3D structure. The refinement of the solution structure of the highly flexible AVP‐like parallel dimer is described to illustrate this process.
The Use of Crown Ethers in Peptide Chemistry – V. Solid‐phase Synthesis of Peptides by the Fragment Condensation Approach using Crown Ethers as Non‐covalent Protecting Groups
Authors: Botti Paolo , Ball Haydn L. , Lucietto Pierluigi , Pinori Massimo , Rizzi Emanuele , Mascagni Paolo
Published: May 2005

We have previously described the conditions by which peptide synthesis by the solid‐phase fragment condensation approach can be carried out using crown ethers as non‐covalent protection for the Nα ‐amino group. Here we demonstrate that the procedure can be extended to large, partially protected peptide fragments possessing free Lys and/or Arg residues. The first step was to ensure that complex formation on the side chain of amino acids was not detrimental to the methodology and exhibited the same solubility and coupling properties as Nα ‐complexed peptides. Thus, a model hexapeptide was synthesized using Fmoc chemistry containing Lys and Arg residues, which, when complexed with 18‐Crown‐6, was readily soluble in DCM and coupled quantitatively to a resin‐bound tetrapeptide. Two tripeptides were then prepared, one containing a free Ser residue, the other free Tyr, to examine the possible occurrence of side reactions. After coupling using standard conditions only the former tripeptide exhibited the formation of the O‐acylation by‐product (5%). Another model hexapeptide containing Lys, Tyr, Ser and Asp protected with a TFA‐stable adamantyl group was complexed with 18‐Crown‐6 and coupled to the resin‐bound tetrapeptide with near quantative yield. Extending the length of the peptide to 21 and 40 residues, which represent sequences Gly52 to Leu72 (21‐mer) and Pro33 to Leu72 (40‐mer) from Rattus norvegicus chaperonin 10 protein, respectively, resulted in partially protected fragments that were readily soluble in water, thus enabling purification by RP‐HPLC. Complexation with 18‐Crown‐6 gave two highly soluble products that coupled to resin‐board tetramer with 68% and 50% coupling efficiencies for the 21‐mer and 40‐mer, respectively. Treatment with 1% DIEA solutions followed by acidolytic cleavage and purification of the major product confirmed that the correct product had been formed, when analysed by amino acid analysis and ESI‐MS. These results served to extend the methodology of non‐covalent protection of large partially protected peptide fragments for the stepwise fragment condensation of polypeptides.
Application of entropy calculations to the determination of transition temperature in zirconium
Authors: Srepusharawoot Pornjuk , Pinsook Udomsilp
Published: June 2005

The Helmholtz free energy is determined in order to calculate the bcc–hcp phase transition temperature in zirconium. The molecular dynamics method is employed to calculate the vibrational entropy which comprises both the harmonic and anharmonic vibrational entropy. Electronic effects are estimated and taken into account. The anharmonic vibrational entropy is determined from the anharmonic free energy and the electronic entropy is calculated via the electronic density of states. By considering the Helmholtz free energy, the bcc–hcp transition temperature from our simulations is 1047 ± 210 K compared to 1135 K from experimental results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐dependent current through a ferromagnetic resonant tunnelling quantum well
Authors: Lebedeva N. , Kuivalainen P.
Published: June 2005

We study the nonequilibrium quantum transport through a ferromagnetic quantum well (FQW) coupled to two nonmagnetic leads. A formal expression for the spin‐polarized current is derived with the Keldysh nonequilibrium‐Green‐function technique. Then the retarded Green function for the FQW, which is needed in the general expression for the transmission coefficient T(E), is calculated by using Zubarev's double‐time‐Green‐function technique. The derived expression for T(E) includes, e.g., the shift and the life‐time broadening of the electronic states inside the FQW due to the tunnelling processes and the strong exchange interaction between the charge carrier spins and the localized spins of the magnetic electrons. Numerical results are presented for a simple FQW model structure consisting of a diluted III–V ferromagnetic semiconductor between the insulating barriers. A single resonant level inside the FQW is coupled to the nonmagnetic leads by tunnelling and to the ferromagnetic subsystem by the exchange interaction. Novel effects predicted by the model are discussed, such as the broadening of the resonant level due to the spin‐disorder scattering in a 2D‐hole gas and the large spontaneous spin‐splitting of the resonant level in a ferromagnetic phase transition. These effects are seen in the calculated T(E) and the spin current through the FQW, which show strong temperature and magnetic field dependences at temperatures close to the Curie temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport through a four‐quantum‐dot ring
Authors: Li Hua , Lü Tianquan , Sun Punan
Published: June 2005

The nonequilibrium Keldysh Green's function technique is used to study the electronic transport property of a four‐quantum‐dot ring under dc bias. The formula for the dc current through the system is obtained. The transmission probability T(ω) as a function of electron energy ω and the differential conductance as a function of the chemical potential of the left reservoir are calculated. Both of them display oscillation structures. When the tunnel coupling amplitude between neighboring dots is sufficiently large, the resonant states of the system depend on the arrangement of single‐dot Fermi levels. In addition, the coupling amplitude to the two reservoirs can also influence the transport property of the system. When the single‐dot Fermi levels of the four dots are all aligned, the electronic spectrum of the system is found to fall within an interval centered at the single‐dot Fermi level with a width of twice the tunnel coupling amplitude between two neighboring dots. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atomistic study of structural simulation and Curie temperature of R2Fe17–xTx (R = Tb, Ho, Er; T = Ti, V, Cr, Mn)
Authors: Qian Ping , Wang Qing‐Lin , Chen Nan‐Xian , Shen Jiang
Published: June 2005

In order to study the effect of ternary element T substitution on the structural properties of R2Fe17–xTx (R = Tb, Ho, Er; T = Ti, V, Cr, Mn), the phase stability and site preference are performed by using pair potentials based on lattice inversion technique. Our results indicate that the Ti, V, Cr and Mn atoms can stabilize R2Fe17–xTx with the hexagonal Th2Ni17‐type structure. Calculated site preference of these stabilizing elements T is found to be the 4f site, which is in agreement with the experiment. Moreover, the decrease of the Curie temperature TC with increasing Mn concentration is explained qualitatively by the exchange‐interaction model. The method utilized in the present investigation offers a rather easy and direct way to study the structural properties of intermetallics. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interfacial steps, dislocations, and inversion domain boundaries in the GaN/AlN/Si (0001)/(111) epitaxial system
Authors: Dimitrakopulos G. P. , Sanchez A. M. , Komninou Ph. , Kehagias Th. , Karakostas Th. , Nouet G. , Ruterana P.
Published: June 2005

The role of substrate steps in the introduction of transformations of interfacial structure and inversion domain boundaries is studied for the GaN/AlN/Si (0001)/(111) epitaxial system using topological analysis and high resolution transmission electron microscopy. This epitaxial system can exhibit distinct interfacial structures at the AlN/Si interface, and transformations from one to the other can be introduced by the steps on the substrate surface. The interfacial steps can exhibit dislocation character and they may accommodate the coexistence of energetically degenerate as well as distinct interfacial structures. A substrate step is identified as a potential cause for pinhole formation. Inversion domain boundaries accommodate interfacial transformations when they emanate from the epitaxial interface and can reduce the coherency dislocation character of interfacial steps. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastic and thermal properties of δ‐plutonium
Authors: Siethoff Hans
Published: June 2005

It has been demonstrated in recent experimental and theoretical studies, that δ‐Pu exhibits highly anisotropic phonon properties. The present paper indicates, that properties related to low‐energy phonons such as Debye temperature and activation energy of self‐diffusion do not reflect these anisotropies, and obey the same laws as other face‐centred cubic metals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin dynamics of exciton polaritons in microcavities
Authors: Shelykh I. A. , Kavokin A. V. , Malpuech G.
Published: June 2005

In this chapter we address a complex set of optical phenomena linked to the spin dynamics of exciton polaritons in semiconductor microcavities. When optically created, polaritons inherit the spin and dipole moment from the exciting light. Their state can be fully characterized by a so‐called “pseudospin” accounting for both spin and dipole moment orientation. However, from the very beginning of their life in a microcavity, polaritons start changing their pseudospin state under effect of effective magnetic fields of different nature and due to scattering with acoustic phonons, defects, and other polaritons. This makes pseudospin dynamics of exciton polaritons rich and complex. It manifests itself in non‐trivial changes in polarization of light emitted by the cavity versus time, pumping energy, pumping intensity and polarization. During the first years of theoretical research on exciton‐polariton relaxation the polarization has been simply neglected. Later it has been understood that the energy and momentum‐relaxation of exciton polaritons are spin‐dependent. It is typically the case in the regime of stimulated scattering when the spin polarizations of initial and final polariton state have a huge effect on the scattering rate between these states. It appeared that critical conditions for polariton Bose‐condensation are also polarization‐dependent. In particular, the stimulation threshold (i.e. the pumping power needed to have a population exceeding 1 at the ground state of the lower polariton branch) has been experimentally shown to be lower under linear than under circular pumping. These experimental observations have stimulated the theoretical research toward understanding of mutually dependent polarization‐ and energy‐relaxation mechanisms in microcavities. The authors of this chapter have been working on theoretical description of different specific effects of polariton spin‐dynamics in microcavities for years. Here we attempted to put together all fragments and to formulate a general approach to the problem that would allow then to consider a variety of particular cases. We start from reminding the main spin‐relaxation mechanisms known for free carriers and excitons. We then overview the most essential experimental results in this field before to present our original formalism which allowed us to interpret the key experimental findings. We are going to discuss only the strong coupling regime leaving aside all polarization effects in VCSELs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recursive generation of natural orbitals in a truncated orbital space
Authors: Li Xiangzhu , Paldus Josef
Published: May 2005

We describe a procedure that generates a subset of low‐lying natural orbitals. It employs a small truncated orbital space, whose dimension is essentially given by the number of natural orbitals we wish to generate. The method is somewhat related to the numerical renormalization group technique. The resulting low‐lying, optimal natural orbitals can then be used in the computation of one‐electron properties, as well as of the energy via a small‐scale configuration interaction (CI), yielding improved potential energy and property surfaces over those obtained with the same method using Hartree–Fock orbitals. The procedure is illustrated on a DZP model of water, considering both the dipole moment and the total energy at the equilibrium and symmetrically stretched geometries. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Theoretical study of the mechanism for spin‐forbidden quenching process O(1D) + CO2(1Σ) → O(3P) + CO2(1Σ)
Authors: Yang Guanghui , Yao Li , Zhang Xin , Meng Qingtian , Han Ke‐Li
Published: May 2005

The mechanism of the spin‐forbidden quenching process O(1D) + CO2(1Σ) → O(3P) + CO2(1Σ) was investigated by ab initio quantum chemistry methods. The calculations showed the singlet potential surface [O(1D)+CO2] is attractive where a strongly bound intermediate complex CO3 is formed in the potential basin without a transition state, whereas the complex CO3 that is formed on the triplet surface [O(3P)+CO3] must overcome a barrier. The complex channel was documented by searching minimum energy intersection points in the region of the bound complex CO3 and calculating spin‐orbit coupling at the point. A direct channel was proposed by a study of cross point of singlet and triplet PESs with different collision angles and calculations of spin‐orbit coupling at those cross points in a nonbound region of the [O(1D)+CO3] system. The mechanism of the energy transfer is discussed on the basis of the theoretical results. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Die Kalibrierung von Wärmeleitungsvakuummetern. The Calibration of Thermal Conductivity Vacuum Gauges
Authors: Breitenbach Jürgen
Published: May 2005

Wärmeleitungsvakuummeter werden in zahlreichen Anwendungen zur Überwachung von Grob‐ und Feinvakuum eingesetzt. Zur Feststellung der Richtigkeit der Messwerte fordern moderne Quälitätsmanagementsysteme eine regelmäßige Kalibrierung. Das Kalibrierlabor des Deutschen Kalibrierdienstes (DKD) der Firma VACUUBRAND verfügt über die Messaufbauten bzw. Messverfahren zum Kalibrieren von Vakuummessgeräten im Messbereich 10‐3 bis 1000 mbar. Die Messtechnik und das Kalibrierverfahren werden anhand von Wärmeleitungsvakuummetern mit digitaler Anzeige erläutert. Neben allgemeinen Angaben zur Kalibrierung werden die Besonderheiten von Wärmeleitungsvakuummetern und deren Auswirkungen auf das Kalibrierverfahren hervorgehoben. Die Bedeutung der Messabweichung und der Messunsicherheit sowie die Interpretation des Kalibrierscheins werden für den Benutzer diskutiert.
Plasmagestützte Oberflächenfunktionalisierung komplex strukturierter, miniaturisierter Kunststoff‐Formteile. Plasma assisted surface functionalization of miniaturized plastic devices
Authors: Besch Wilfried , Schröder Karsten , Ohl Andreas
Published: May 2005

Für die Vorbereitung von Kunststoffbauteilen für Beschichtungen, Fügeprozesse und ähnliche Zwecke mittels Oberflächenfunktionalisierung kommen unterschiedliche Verfahren in Betracht. Die Verfahren unterscheiden sich in ihren Leistungsmerkmalen deutlich, sowohl in Bezug auf die erzielbaren Oberflächeneffekte als auch hinsichtlich verfahrenstechnischer Gegebenheiten. Für die Funktionalisierung komplex strukturierter Kunststoff‐Formteile kann gezeigt werden, dass hier auf Niederdruckplasmen basierende Verfahren sowohl hinsichtlich der Qualität der Funktionalisierung als auch der Prozessführung Vorteile aufweisen. Für sehr kleine, filigrane und komplexe Bauteile wird die besondere Spaltgängigkeit von Plasmen zum entscheidenden Kriterium. Dazu angestellte Untersuchungen mit Hilfe von Gasphasen‐Pfropfreaktionen zeigen, dass auch in Spalten, deren Abmessungen weit unter dem für andere, alternative Prozesse zugänglichen Bereich liegen, gleichmäßige Behandlungen erreicht werden können.
Transcription factor XBP‐1 is expressed during osteoblast differentiation and is transcriptionally regulated by parathyroid hormone (PTH)
Authors: Zambelli A. , Mongiardini E. , Villegas S.N. , Carri N.G. , Boot‐Handford R.P. , Wallis G.A.
Published: June 2005

X‐box‐binding protein 1 (XBP‐1) is a basic‐region leucine zipper protein in the cyclic AMP response element binding protein/activating transcription factor (CREB/ATF) family of transcription factors involved in different cell‐differentiation processes. We have investigated the expression of XBP‐1 in differentiating MC3T3‐E1 osteoblastic cells. Cultures were treated with ascorbic acid (AA) and β‐glycerophosphate (BGP) to induce differentiation. Under these conditions, the basal transcription of xbp‐1 increases at day 2 following induction, peaks at day 5 and decreases thereafter. This result showed that xbp‐1 gene is differentially expressed during MC3T3‐E1 cell differentiation. Detection of XBP‐1 by immunofluorescence at days 0 (control culture without AA and BGP), 8 and 21 showed that the protein has a major cytoplasmic perinuclear location. In addition, xbp‐1 is transcriptionally upregulated by parathyroid hormone within 2.5 h of treatment and decreases thereafter.
Human glutamylcysteine synthetase protects HEK293 cells against UV‐induced cell death through inhibition of c‐Jun NH2‐terminal kinase
Authors: Fan Yumei , Wu Dongmei , Jin Lina , Yin Zhimin
Published: June 2005

Human glutamylcysteine ligase catalytic subunit (GCLC) is the rate‐limiting enzyme for glutathione synthesis. The heavy subunit possesses all the catalytic activities. UV irradiation (UV‐C, 30 J/m2) induced apoptosis in HEK293 cells, but the morphological changes were inhibited significantly by expression of GCLC. MTS assay and flow cytometry results also indicated that GCLC and JNK1APF expression enhanced cellular resistance to UV irradiation. Western blotting showed that irradiation strongly activated the c‐Jun NH2‐terminal kinases (JNKs) and caspase‐3 as well as p38 in HEK293 cells. Interestingly, existing data show that GCLC blocks JNK1 phosphorylation but does not affect p38 phosphorylation. Therefore, overexpression of GCLC protected HEK293 cells against UV irradiation‐induced cell death by inhibiting the phosphorylation and activation of JNK1, concomitantly with the inhibition of caspase‐3 activation and p21WAF1‐luciferase activity downstream of JNK.
Human Orf (Ecthyma Contagiosum)
Authors: GEORGIADES G. , KATSAROU A. , DIMITROGLOU K.
Published: June 2005

Orf is a viral cutaneous infection typically seen on the hands of people involved in sheep and goat farming. We report 31 cases of orf and consider its pathology, characteristic appearance, diagnosis, treatment and complications.
Juxtacortical Chondroma of the Hand: Treatment by Resection of the Tumour and the Adjacent Bone Cortex
Authors: TAKADA A. , NISHIDA J. , AKASAKA T. , SHIRAISHI H. , FURUMACHI K. , TAJIMA K. , OKADA K. , SHIMAMURA T.
Published: June 2005

A recurrence of a juxtacortical chondroma of the finger after marginal excision prompted us to review the treatment of this condition. Although the recommended treatment is simple curettage or marginal excision, the reported recurrence rate is significantly higher for lesions in the hand than those in other locations and recurrences only occurred in patients who had local treatments which did not include excision of the adjacent bone cortex.

We report five patients with juxtacortical chondroma of the fingers. The first patient underwent marginal excision without resection of the underlying bone cortex. The other four patients underwent intralesional, marginal or wide excisions of tumour with resection of the bone cortex underlying the lesion. Recurrence was only seen in the patient who did not undergo resection of the bone cortex. Resection of the underlying bone cortex after excision of this tumour may be advisable for the treatment of this tumour in the hand to reduce the rate of recurrence.
A history of organized persecution and conservation of wildlife: species categorizations in Finnish legislation from medieval times to 1923
Authors: Mykrä Sakari , Vuorisalo Timo , Pohja-Mykrä Mari
Published: June 2005

Attitudes towards wild animals are reflected through history in various categorizations of species. For example, changes in the useful-harmful dichotomy of species have affected policy decisions during the long history of organized pest persecution as well as during the much more recent rise of nature conservation. The first hunting legislation in Finland dates back more than 650 years, to times when the country belonged to the Kingdom of Sweden. From those times to the early 20th century various acts of law exhibited a marked variation in placing species into useful and harmful categories. The dichotomy seems to be based upon fundamental ecological interactions between humans and other species. We show that the varying interest in pest persecution as well as important conservation milestones have been associated with contemporary human-animal relations such as the attitudes of decision makers and laymen towards wild animals, and the public awareness of species conservation issues.
Super-shedding cattle and the transmission dynamics ofEscherichia coliO157
Authors: MATTHEWS L. , McKENDRICK I. J. , TERNENT H. , GUNN G. J. , SYNGE B. , WOOLHOUSE M. E. J.
Published: June 2005

The prevalence ofEscherichia coliO157 displays striking variability across the Scottish cattle population. On 78% of farms, in a cross-sectional survey of 952, no shedding ofE. coliO157 was detected, but on a small proportion, ∼2%, very high prevalences of infection were found (with 90–100% of pats sampled being positive). We ask whether this variation arises from the inherent stochasticity in transmission dynamics or whether it is a signature of underlying heterogeneities in the cattle population. A novel approach is taken whereby the cross-sectional data are viewed as providing independent snapshots of a dynamic process. Using maximum-likelihood methods to fit time-dependent epidemiological models to the data we obtain estimates for the rates of immigration and transmission ofE. coliO157 infection – parameters which have not been previously quantified in the literature. A comparison of alternative model fits reveals that the variation in the prevalence data is best explained when a proportion of the cattle are assumed to transmit infection at much higher levels than the rest – the so-called super-shedders. Analysis of a second dataset, comprising samples taken from 32 farms at monthly intervals over a period of 1 year, additionally yields an estimate for the rate of recovery from infection. The pattern of prevalence displayed in the second dataset also strongly supports the super-shedder hypothesis.
Diurnal rhythm of cone opsin expression in the teleost fish
Haplochromis burtoni
Authors: HALSTENBERG SVEN , LINDGREN KRISTIN M. , SAMAGH SANJUM P. S. , NADAL-VICENS MIREYA , BALT, STEVE , FERNALD RUSSELL D.
Published: June 2005

The biochemical and morphological specializations of rod and cone
photoreceptors reflect their roles in sight. The apoprotein opsin, which
converts photons into chemical signals, functions at one end of these
highly polarized cells, in the outer segment. Previous work has shown that
the mRNA of rod opsin, the opsin specific to rods, is renewed in the outer
segment with a diurnal rhythm in the retina of the teleost fish
Haplochromis burtoni. Here we show that in the same species, all
three cone opsin mRNAs (blue, green, and red) also have a diurnal rhythm
of expression. Quantitative real-time polymerase chain reaction (PCR) with
primer pairs specific for the cone photoreceptor opsin subtypes was used
to detect opsin mRNA abundance in animals sacrificed at 3-h intervals
around the clock. All three cone opsins were expressed with diurnal
rhythms similar to each other but out of phase with the rod opsin rhythm.
Specifically, cone opsin expression occurs at a higher level near the
onset of the dark period, when cones are not used for vision. Finally, we
found that the rhythm of cone opsin expression in fish appears to be light
dependent, as prolonged darkness changes normal diurnal expression
patterns.
Contrast response of temporally sparse dichoptic multifocal visual
evoked potentials
Authors: MADDESS TED , JAMES ANDREW CHARLES , BOWMAN ELIZABETH ANNE
Published: June 2005

Temporally sparse stimuli have been found to produce larger multifocal
visual evoked potentials than rapid contrast-reversal stimuli. We compared
the contrast-response functions of conventional contrast-reversing (CR)
stimuli and three grades of temporally sparse stimuli, examining both the
changes in response amplitude and signal-to-noise ratio (SNR). All stimuli
were presented dichoptically to normal adult human subjects. One stimulus
variant, the slowest pattern pulse, had interleaved monocular and
binocular stimuli. Response amplitudes and SNRs were similar for all
stimuli at contrast 0.4 but grew faster with increasing contrast for the
sparser stimuli. The best sparse stimulus provided an SNR improvement that
corresponded to a recording time improvement of 2.6 times relative to that
required for contrast reversing stimuli. Multiple regression of
log-transformed response metrics characterized the contrast-response
functions by fitting power-law relationships. The exponents for the two
sparsest stimuli were significantly larger (P < 0.001) than
for the CR stimuli, as were the mean response amplitudes and
signal-to-noise ratios for these stimuli. The contrast-dependent response
enhancement is discussed with respect to the possible influences of rapid
retinal contrast gain control, or intracortical and cortico-geniculate
feedback.
Plasma membrane localization and function of TRPC1 is dependent on its interaction with β-tubulin in retinal epithelium cells
Authors: BOLLIMUNTHA SUNITHA , CORNATZER ERIC , SINGH BRIJ B
Published: June 2005

Mammalian homologues of theDrosophilacanonical Transient Receptor Potential (TRPC) protein have been proposed to encode the store-operated Ca2+influx (SOC) channel(s). This study examines the role of TRPC1 in the SOC mechanism of retinal cells.htrpc1transcript was detected in bovine retinal and in human adult retinal pigment epithelial (ARPE) cells. Western blot analysis also confirmed the expression of TRPC1 protein in neuronal cells including retina and ARPE cells. To determine the role of TRPC1 protein in retinal cells, TRPC1 was recombinantly expressed in ARPE cells and changes in intracellular Ca2+were analyzed. ARPE cells stably transfected withhtrp1cDNA displayed 2-fold higher Ca2+influx with no significant increase in the basal influx. Consistent with this the overexpressed TRPC1 protein was localized in the plasma membrane region of ARPE cells. Interestingly, both bovine retinal tissues and ARPE cells showed that TRPC1 protein co-localizes and could be co-immunoprecipitated with β-tubulin. Disruption of tubulin by colchicine significantly decreased both plasma membrane staining of the TRPC1 protein and Ca2+influx in ARPE cells. These results suggest that TRPC1 channel protein is expressed in retinal cells, further, targeting/retention of the TRPC1 protein to the plasma membrane in retinal cells is mediatedviaits interaction with β-tubulin.
Diurnal and circadian retinomotor movements in zebrafish
Authors: MENGER GUS J. , KOKE JOSEPH R. , CAHILL GREGORY M.
Published: June 2005

Key indicators of circadian regulation include the persistence of physiological rhythmicity in the absence of environmental time cues and entrainment of this rhythmicity by the ambient light cycle. In some teleosts, the inner segments of rod and cone photoreceptors contract and elongate according to changes in ambient lighting and the circadian cycle. Pigment granules in the retinal pigment epithelium (RPE) disperse and aggregate in a similar manner. Collectively, these movements are known as retinomotor movements. We report the histological characterization of diurnal and circadian retinomotor movements in zebrafish,Danio rerio. Adult fish subjected to a 14:10 light:dark (LD) cycle, constant darkness (DD), or constant light (LL) were sacrificed at 1–13 h intervals and processed for semithin sectioning of the retina. Using bright-field microscopy, 15 measurements of pigment granule position and the inner segment lengths of 30 rods and 30–45 cones were collected from the central third of the dorso-optic retina per time point. In LD, rods and cones followed a clear diurnal rhythm in their inner segment movements. Short-single, UV-sensitive cones were found to contract significantly 1 h before light onset in LD conditions. In DD conditions, the inner segments movements of short-single and double cones displayed statistically significant rhythms. RPE pigment granule movements are rhythmically regulated in both LD and DD although fluctuations are damped in the absence of photic cues. No significant retinomotor movements were observed in LL. These findings indicate retinomotor movements in zebrafish are differentially regulated by an endogenous oscillator and by light-dependent mechanisms.
Visual pigment composition in zebrafish: Evidence for a
rhodopsin–porphyropsin interchange system
Authors: ALLISON W. TED , HAIMBERGER THEODORE J. , HAWRYSHYN CRAIG W. , TEMPLE SHELBY E.
Published: June 2005

(article appeared in Visual Neuroscience (2004), 21,
945–952)

As a result of a production error, the footnote to this article was
incorrect. It should have stated that “the authors are in
alphabetical order” instead of stating that “all authors
contributed equally to this paper.” Because of the nature of this
error, the online version has been corrected.
Optimal interpolation analysis of high‐latitude ionospheric electrodynamics using empirical orthogonal functions: Estimation of dominant modes of variability and temporal scales of large‐scale electric fields
Authors: Matsuo Tomoko , Richmond Arthur D. , Lu Gang
Published: June 2005

In this paper the optimal interpolation method, in conjunction with empirical orthogonal function (EOF) bases and the maximum likelihood method for online error covariance parameter estimation, is successfully implemented for the objective analysis of large‐scale high‐latitude ionospheric electrodynamic variables. This study demonstrates how this methodology can be used to extract information about the temporal and spatial coherence of the large‐scale electric field for a magnetic cloud event on 10–11 January 1997. Compared with the temporal persistence of the interplanetary magnetic field (IMF) and solar wind parameters, the timescale of the spatially coherent part of the electric field, on the spatial scale of the EOFs, is shorter. The principal components of the high‐latitude electric field are analyzed during two periods when either the IMF BY or BZ component was relatively steady while the other component varied. The first principal component, not surprisingly, generally reflects the change in the ionospheric convection pattern predicted by IMF‐dependent empirical models and thus tends to represent changes in the convection that are directly driven by solar wind–magnetosphere interactions. However, it is the second principal component that is more strongly correlated with the westward auroral electrojet, suggestive of a link to substorm phenomena.
Computer experiments of amplitude‐modulated Langmuir waves: Application to the Geotail observation
Authors: Usui H. , Furuya H. , Kojima H. , Matsumoto H. , Omura Y.
Published: June 2005

We studied the amplitude modulation of Langmuir waves in the process of electron‐beam interaction by performing particle‐in‐cell computer experiments. Without applying the conventional nonlinear theories such as the decay instability and the modulation instability, we confirmed that the amplitude modulation observed in the computer experiments can be accounted for by “nonlinear trapping theory” which explains the spatial scales of the modulation with nonlinear electron trapping in electrostatic wells. In order to apply the nonlinear trapping theory to observational data, we modified the theory to be applicable to temporal data. We basically confirmed the agreement between the theoretical estimate and the temporal scale of wave packets observed in the computer experiments. We found that temporal waveforms obtained in the computer experiments are quite similar to those observed by the Geotail spacecraft. By applying the theoretical estimate of temporal scales of wave packets to the Geotail wave data, we found that the phase velocity of the excited Langmuir waves, which is close to the electron beam velocity, can be roughly estimated with time resolution much higher than the particle observation.
Influence of the Madden‐Julian Oscillation on wintertime surface air temperature and cold surges in east Asia
Authors: Jeong Jee‐Hoon , Ho Chang‐Hoi , Kim Baek‐Min , Kwon Won‐Tae
Published: June 2005

The variations of wintertime surface air temperature (SAT) and the occurrences of cold surges over east Asia in association with the Madden and Julian Oscillation (MJO) are examined. The MJO is defined as a combination of the two leading empirical orthogonal function modes of 850 and 200 hPa zonal winds and outgoing longwave radiation in the tropics. The spatial pattern and magnitude of SAT anomalies over east Asia significantly change with respect to MJO phases. Composite analysis reveals that the MJO‐SAT relationship is mainly affected by strong temperature advection in the lower troposphere. In addition, occurrences of cold surges are identified using objectively determined synoptic criteria, and their relation to the MJO is analyzed. Most extreme cold surges occur when the MJO convection center is located over the Indian Ocean, and it is suggested that MJO‐induced circulation anomalies may reinforce the amplification of normal cold surges to extreme cold surges.
Organization of mesoscale convective systems: 1. Numerical experiments
Authors: Cheng Anning
Published: June 2005

The shear‐parallel and shear‐perpendicular linear mesoscale convective systems (MCSs) are studied by a three‐dimensional nonhydrostatic cloud resolving model. On the basis of previous observational studies, a unique “reference layer” can be defined for both MCSs. A shear‐parallel MCS can be distinguished from a shear‐perpendicular MCS by the shear and moist instability in the reference layer only regardless of the shear at the other levels. This drastically simplifies the problem at hand. The reference layer is located below 400 mbar. It must be thicker than 200 mbar, and the mean shear of the layer must be larger than 2 m s−1 per 100 mbar. Its stratification is unstable or near neutral. The shear‐parallel MCS is produced when the reference layer is near neutral or less unstable. In its first phase the new cells are produced by the basic wave propagation mechanism, modified by the shear. The growth rate is relatively small, and there is no cold pool in this phase. In the second phase the updrafts become strong and expand. A cold pool is formed along the shear‐parallel direction, and the new cells are formed along the edge of the cold pool. The interaction between the shear and the updraft plays a major role in the formation of the shear‐parallel MCSs. The cold pool outflow convergence and the interaction between the cold pool and the shear are also important in the second phase. On the other hand, the shear‐perpendicular MCS is produced when the reference layer is highly unstable. The cold pool is always strong, and the interaction between the shear and cold pool plays a major role in the formation of the linear structure in agreement with the theory proposed by Rotunno et al. (1988). Sensitivity experiments indicate that both types of MCS organization can exist without precipitation or a cold pool and in the dry system. This finally provides a foundation for the theoretical analysis presented in the companion paper.