bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Structural Characterization of a Halide‐Free Rhombohedral Silver‐Alkynyl Cage Complex [Ag14(C2tBu)12][BF4]2
Authors: Abu‐Salah Omar M. , Ja’far Mohammed H. , Al‐Ohaly Abdel Razzak , Al‐Farhan Khalid A. , Al‐Enzi Hamda S. , Dolomanov Oleg V. , Howard Judith A. K.
Published: May 2006

The novel cationic complex [Ag14(C2tBu)12]2+ has been synthesized by four reactions: reaction of [Ag(C2tBu)]n and AgBF4 in acetone in a 6:1 mole ratio, that of HC≡CtBu and AgBF4 in water in the absence of a base, treatment of [AgC2tBu]n with HBF4 in acetone or that of {[Ag3(C2tBu)2][BF4]}n with [Ag(C2tBu)]n in a 1:4 mole ratio. Single‐crystal X‐ray studies showed it to be a hexacapped cube of silver(I) atoms, with twelve η1, μ3‐C2tBu ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Solvothermal Synthesis, Crystal Structures, and Properties of New Selenidoantimonates [Ln(en)4(SbSe4)] (Ln = La, Nd) and [Sm(en)4]SbSe4·0.5en: The First Example of an SbSe43– Anion Acting as a Ligand to a Lanthanide Complex
Authors: Jia Ding‐Xian , Zhao Qian‐Xin , Zhang Yong , Dai Jie , Zhou Jian
Published: May 2006

Three new lanthanide selenidoantimonates [Ln(en)4(SbSe4)] [Ln = La (1), Nd (2)] and [Sm(en)4]SbSe4·0.5en (3) (en = ethylenediamine) were first synthesized by treating LnCl3, Sb, and Se in a stoichiometric ratio with en under mild solvothermal conditions. Compounds 1 and 2 are isostructural. The Ln3+ ion has a nine‐coordinate environment involving eight N atoms from four en ligands and one Se atom from the SbSe43– anion forming a distorted bicapped pentagonal bipyramid. [La(en)4(SbSe4)] and [Nd(en)4(SbSe4)] are the first examples of solvothermally synthesized selenidoantimonates with an SbSe43– anion acting as a ligand in a lanthanide complex. The crystal structure of 3 contains an isolated bicapped trigonal‐prismatic coordinated [Sm(en)4]3+ cation, a tetrahedral SbSe43– anion, and half a free en molecule in its asymmetric unit. The bandgaps of 2.22 eV for 1, 2.33 eV for 2, and 2.54 eV for 3 have been derived from optical absorption spectra. Compound 1 loses the en ligands in one step, whereas compound 2 loses them in two steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Continuous removal of ammonium ion by ion exchange in the presence of organic compounds in packed columns
Authors: Jorgensen Tony C , Weatherley Laurence R
Published: May 2006

The removal of ammonia from wastewaters after secondary biological treatment can successfully be achieved by ion exchange. However, the presence of residual organic compounds can impart significant influence on the uptake and their presence may need to be considered during the design of a treatment system. The aim of this work was to determine the effect of the presence of certain organic compounds upon the uptake of ammonium ion and column breakthrough. Two organic contaminants were considered, including citric acid and protein (as whey protein isolate). Three cationic exchangers were used and included the natural zeolite clinoptilolite, the gel resin Dowex 50w‐x8, and a macronet resin, Purolite MN‐500. The influence of regeneration upon column breakthrough behaviour was also determined. The results showed that the presence of organic compounds had variable effects on ammonium ion uptake. In the case of clinoptilolite the presence of protein appeared to have very little effect upon breakthrough capacity. In the case of the clinoptilolite and the MN500 a substantial reduction of breakthrough capacity was observed in the presence of citric acid. In the case of clinoptilolite a very significant increase in column breakthrough performance was observed after cycles of exhaustion and regeneration. This was not observed in the case of the synthetic resins, which showed a more consistent performance from run to run. Overall the Dowex50w‐x8 gave the highest breakthrough capacity for ammonium ion removal of 700 bed volumes. Regenerated clinoptilolite showed a maximum breakthrough capacity of 450 bed volumes, and MN‐500 a consistent breakthrough capacity of 300 bed volumes. Copyright © 2006 Society of Chemical Industry
Laccase‐catalysed oxidation of aqueous triclosan
Authors: Kim Young‐Jin , Nicell James A
Published: May 2006

A study was conducted on the ability of laccase from Trametes versicolor to catalyse the oxidation of triclosan, an antibacterial agent of significant commercial importance and environmental concern. Laccase was able to catalyse the transformation of triclosan under a variety of conditions and achieve a substantial decrease in toxicity of the reaction mixture. The optimal pH for triclosan transformation was approximately 5, with a broad optimum in the range 4–6. Treatment could be achieved at elevated temperatures, but at the expense of higher rates of inactivation. Treatment efficiency and reaction rates were substantially improved through the use of a protective additive, poly(ethylene glycol) (PEG‐35 000), and a mediator, 2,2′‐azino‐bis(3‐ethylbenzthiazoline)‐6‐sulfonic acid (ABTS). However, both compounds negatively affected the toxicities of treated solutions. The presence of ions including sulfite, sulfide, cyanide, chloride, iron(III) and copper(II) resulted in reduced treatment efficiency. Copyright © 2006 Society of Chemical Industry
Metabolic GHB precursor succinate binds to γ‐hydroxybutyrate receptors: Characterization of human basal ganglia areasnucleus accumbensandglobus pallidus
Authors: Molnár Tünde , Fekete Erzsébet Kútiné , Kardos Julianna , Simon‐Trompler Edit , Palkovits Miklós , Emri Zsuzsa
Published: May 2006

Binding of the metabolic γ‐hydroxybutyrate (GHB) precursor succinate to NCS‐382‐sensitive [3H]GHB‐labeled sites in crude synaptosomal or purified synaptic membrane fractions prepared from the humannucleus accumbens(NA),globus pallidus(GP) and rat forebrain has been shown. This site can be characterized by binding of ethyl hemisuccinate and gap‐junction blockers, including carbenoxolone hemisuccinate and β‐GRA. There was no significant binding interaction between GABABreceptor ligands (CGP 55845, (R)‐baclofen) and these [3H]GHB‐labeled sites. GHB, NCS‐382 and succinate binding profile of [3H]GHB‐labeled sites in rat forebrain, human NA or GP synaptic membranes were similar. The synaptic fraction isolated from the rat forebrain was characterized by GHB binding inhibition constants:Ki,NCS‐382= 1.2 ± 0.2 μM,Ki,GHB= 1.6 ± 0.3 μM andKi,SUCCINATE= 212 ± 66 μM. In crude membranes containing mainly extrasynaptic membranes, distinct GHB and GABABreceptor sites were found in the NA. By contrast, extrasynaptic GABABreceptor sites of rat forebrain and GP were GHB‐ and succinate‐sensitive, respectively. The heterogeneity of GABABsites found in native membranes indicates GABABreceptor‐dependent differences in GHB action. Based on these findings, we suggest that succinate (and possibly drugs available as succinate salt derivatives) can mimic some of the actions of GHB. © 2006 Wiley‐Liss, Inc.
Design and Control of Copolymer Composition Distribution in Living Radical Polymerization Using Semi‐Batch Feeding Policies: A Model Simulation
Authors: Wang Rui , Luo Yingwu , Li Bogeng , Sun Xiaoying , Zhu Shiping
Published: May 2006

Summary: Although controlled/living radical copolymerization has been extensively studied, the control of copolymer composition distribution receives little attention. In this paper, taking RAFT copolymerization as an example, we develop a mathematical model and simulate copolymerization systems with various reactivity ratios. It is demonstrated that through semi‐batch operations with programmed profiles of slow monomer feeding rate, precise control over copolymer composition distribution (uniform and designed gradient distributions) along polymer chain can be achieved. It is also found that the semi‐batch operations have lower rates of polymerization than their batch counterparts. The reason for this difference is analyzed, and the magnitude depends on the reactivity ratios and targeted copolymer composition. The improvement of the semi‐batch rate by distributing a part of the initiator amount to the monomer feeding tank is found to be minor.

Model‐based design and control over composition distribution of gradient copolymers implemented by semi‐batch operations.

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Model‐based design and control over composition distribution of gradient copolymers implemented by semi‐batch operations.
NF‐κB and cancer: Mechanisms and targets
Authors: Karin Michael
Published: May 2006

In addition to being a central coordinator of immune responses, NF‐κB signaling also plays a critical role in cancer development and progression and it may determine the response to therapy. NF‐κB activation was shown to provide a critical mechanistic link between inflammation and cancer and is a major factor that controls the ability of both preneoplastic and malignant cells to resist apoptosis‐based tumor surveillance mechanisms. NF‐κB may also be involved in regulation of tumor angiogenesis and invasiveness. Importantly, NF‐κB and the signaling pathways that mediate its activation have become attractive targets for development of new chemopreventive and chemotherapeutic approaches. © 2006 Wiley‐Liss, Inc.
Transcriptional regulation via cysteine thiol modification: A novel molecular strategy for chemoprevention and cytoprotection
Authors: Na Hye‐Kyung , Surh Young‐Joon
Published: May 2006

Chemoprevention refers to the use of defined nontoxic chemical regimens to inhibit, reverse, or retard the process of multistage carcinogenesis that involves multiple signal transduction events. Identification of signaling molecules associated with carcinogenesis as prime targets of chemopreventive agents has become an area of great interest. Recent studies have implicated cysteine thiols present in various transcription factors, such as NF‐κB, AP‐1, and p53 as redox sensors in transcriptional regulation of many genes essential for maintaining cellular homeostasis. Some chemopreventive and cytoprotective agents have been found to target cysteine thiols present in key transcription factors or their regulators, thereby suppressing aberrant over‐activation of carcinogenic signal transduction or restoring/normalizing or even potentiating cellular defense signaling. The focus of this review is the oxidation or covalent modification of thiol groups present in key representative redox‐sensitive transcription factors and their regulating molecules as a unique strategy for molecular target‐based chemoprevention and cytoprotection. © 2006 Wiley‐Liss, Inc.
In vivo estimation of the flow‐driven adiabatic inversion efficiency for continuous arterial spin labeling: A method using phase contrast magnetic resonance angiography
Authors: O'Gorman Ruth L. , Summers Paul E. , Zelaya Fernando O. , Williams Steven C. R. , Alsop David C. , Lythgoe David J.
Published: May 2006

The accurate quantification of perfusion with arterial spin labeling (ASL) requires consideration of a number of factors, including the efficiency of the inversion and control pulses used for spin labeling. In this study the effects of spin velocity on continuous ASL efficiency when using the amplitude modulated control strategy were investigated using simulations of the Bloch equations. The inversion efficiency was determined in vivo by combining the simulations with phase‐contrast velocity mapping data acquired at the level of the tagging plane. Using this novel method, an average inversion efficiency of 69% was calculated for a group of 28 subjects, in good agreement with experimental data reported previously. There was, however, a large range in inversion efficiency measured across the subject group (50–76%), indicating that the velocity dependence of the amplitude modulated control efficiency may introduce additional variability into the perfusion calculations if not properly taken into account. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Effect of partial bladder outlet obstruction on nitrotyrosine levels and their correlation with contractile function
Authors: Mannikarottu Anita , Lin Alpha Dian‐Yu , Whitebeck Catherine , Leggett Robert , Kogan Barry , Levin Robert
Published: May 2006

Aims

It has been demonstrated that partial bladder outlet obstruction (PBOO) causes free radical generation that, in turn, results in cellular and subcellular damage. We tested the hypothesis that nitration of proteins is associated with contractile dysfunctions in obstructive bladder disease.

Methods

Thirty rabbits were subjected to 1–28 days of partial outlet obstruction. Sham operated rabbits served as controls. Western blotting was used to determine the amount of nitrotyrosine level at the protein level. At each time point, isolated strips of bladder body were mounted in individual baths and the contractile response to field stimulation (FS), carbachol, and KCl determined.

Results

Bladder weight increased rapidly during the first 7 days and then increased slowly thereafter. There was a fourfold increase in the amount of nitrotyrosine in the 7 day obstructed groups when compared to sham controls and the levels remain elevated at 14 and 28 days of obstruction. Contractile dysfunction in response to FS (8 and 32 Hz) was noted as early as 1 day after obstruction and increased progressively over the study period. The decrease in response to carbachol and KCl was significant only after 3 days of obstruction and the progressive increase in dysfunction was slower than with FS.

Conclusions

PBOO is accompanied by an increase in nitrotyrosine, a marker of free radical damage. Simultaneously there was a progressive decrease in contractility of detrusor smooth muscles (DSMs). Nitrotyrosine may be usable as a marker of free radical damage and reperfusion injury. Neurourol. Urodynam. © 2006 Wiley‐Liss, Inc.
A heuristic for maximizing the number of on‐time jobs on two uniform parallel machines
Authors: Koulamas Christos , Kyparisis George J.
Published: May 2006

We consider the problem of maximizing the number of on‐time jobs on two uniform parallel machines. We show that a straightforward extension of an algorithm developed for the simpler two identical parallel machines problem yields a heuristic with a worst‐case ratio bound of at least
$5\over 3$. We then show that the infusion of a “look ahead” feature into the aforementioned algorithm results in a heuristic with the tight worst‐case ratio bound of $3\over 2$, which, to our knowledge, is the tightest worst‐case ratio bound available for the problem. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006
Effects of comonomer sequential structure on thermal and crystallization behaviors of biodegradable poly(butylene succinate‐co‐butylene terephthalate)s
Authors: Li Faxue , Xu Xinjian , Hao Qinghui , Li Qiaobo , Yu Jianyong , Cao Amin
Published: May 2006

In this work, new investigations on the effect of comonomer sequential structure on the thermal and crystallization behaviors and biodegradability have been implemented for the biodegradable poly(butylene succinate‐co‐butylene terephthalate) (PBST) as well as aliphatic poly(butylene succinate) (PBS). At first, these copolyesters were efficiently synthesized from dimethyl succinate and/or dimethyl terephthalate and 1,4‐butanediol via condensation polymerization in bulk. Subsequently, their molecular weights and macromolecular chain structures were analyzed by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. By means of differential scanning calorimeter (DSC) and wide‐angle X‐ray diffractometer (WAXD), thermal and crystallization behaviors of these synthesized aromatic–aliphatic copolyesters were further explored. It was demonstrated that the synthesized copolyesters were revealed to have random comonomer sequential structures with thermal and crystallization properties strongly depending on their comonomer molar compositions, and that crystal lattice structures of the new crystallizable copolyesters shifted from the monoclinic crystal of semicrystalline PBS to triclinic lattice of the poly(butylene terephthalate) (PBT) with increasing the terephthalate comonomer composition, and the minor comonomer components were suggested to be trapped in the crystallizable component domains as defects. In addition, the enzymatic degradability was also characterized for the copolyesters film samples. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1635–1644, 2006
Fabrication of suspended GaN microstructures using GaN‐on‐patterned‐silicon (GPS) technique
Authors: Yang Z. , Wang R. N. , Jia S. , Wang D. , Zhang B. S. , Lau K. M. , Chen K. J.
Published: May 2006

We demonstrate a technique for fabricating suspended gallium nitride (GaN) microstructures without direct etching of GaN. The process combines a selective area growth of GaN‐on‐patterned‐silicon substrate (GPS) and a subsequent sacrificial wet etching of the silicon under the GaN structures. Both anisotropic and isotropic wet etching techniques are used to carry out the sacrificial etching. The pattern‐dependent lateral growth property of GaN growth is also discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystallization of GaN by HVPE on pressure grown seeds
Authors: Grzegory I. , Lucznik B. , Bockowski M. , Pastuszka B. , Kamler G. , Nowak G. , Krysko M. , Krukowski S. , Porowski S.
Published: May 2006

Growth of GaN under pressure from solution in gallium results in almost dislocation free plate‐like crystals but with size limited to approx. 1 cm (lateral) and 100 µm (thickness). On the other hand, deposition of GaN by HVPE on the pressure grown substrates allows stable crystallization with rates of a few hundreds µm/h. The crystals with a thickness exceeding 2 mm are grown in this way. However, in these thick GaN crystals grown directly on almost dislocation free substrates quite high number of dislocations appears if the crystal thickness exceeds certain critical value probably due to a small lattice mismatch between GaN grown by HVPE and the heavily doped pressure grown substrates Since the critical thickness for defect generation is of the order of 100 µm, almost dislocation free layers (density below 104 cm–2) thinner than 100 µm were grown. The pressure grown substrates were then removed by mechanical polishing, or conductivity sensitive electrochemical etching (for strongly n‐type substrates). Then the HVPE low dislocation density GaN platelets were used as substrates for the growth of a few mm thick bulk GaN crystals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐quality InN grown on KOH wet etched N‐polar InN template by RF‐MBE
Authors: Muto D. , Naoi H. , Araki T. , Kitagawa S. , Kurouchi M. , Na H. , Nanishi Y.
Published: May 2006

We have succeeded in dramatically decreasing the density of dislocations in InN by regrowing InN films on micro‐facetted N‐polar InN templates. The micro‐facetted N‐polar InN templates were formed by wet etching in a 10 mol/l KOH solution. InN films were regrown on the micro‐facetted N‐polar InN templates and on flat surface N‐polar InN templates for comparison by radio‐frequency plasma‐assisted molecular beam epitaxy. InN regrown on micro‐facetted InN had considerably smaller twist distribution than that grown on the flat InN templates. From transmission electron microscopy observation, it was confirmed that the InN grown on the micro‐facetted InN template had much lower density of dislocations than that grown on the flat InN template, and moreover the propagation of edge dislocations was almost completely terminated at the interface between the regrown InN and the micro‐facetted InN template. Based on the results, we propose that regrowth of InN on micro‐facetted InN templates is an effective way to obtain high‐quality InN films. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
1.5 µm luminescence of silicon nanowires fabricated by thermal evaporation of SiO
Authors: Jia G. , Kittler M. , Su Z. , Yang D. , Sha J.
Published: May 2006

Silicon nanowires (NWs) fabricated by thermal evaporation of SiO were studied by cathodoluminescence. A band around 1550 nm (0.8 eV) was observed. It appears above 225 K and its intensity increases with increasing temperature. The broad band consists of the defect‐related D1 and D2 lines and is supposed to be formed by extended defects within the NWs that are decorated with oxygen. Moreover, luminescence bands are found that are related to Si oxide and/or the interface between Si and Si oxide. In addition, the Si band‐to‐band line and the G center are observed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Promoting student engagement in science: Interaction rituals and the pursuit of a community of practice
Authors: Olitsky Stacy
Published: May 2006

This study explores the relationship between interaction rituals, student engagement with science, and learning environments modeled on communities of practice based on an ethnographic study of an eighth grade urban magnet school classroom. It compares three interactional events in order to examine the classroom conditions and teacher practices that can foster successful interaction rituals (IRs), which are characterized by high levels of emotional energy, feelings of group membership, and sustained interest in the subject. Classroom conditions surrounding the emergence of successful IRs included mutual focus, familiar symbols and activity structures, the permissibility of some side‐talk, and opportunities for physical and emotional entrainment. Sustained interest in the topic beyond the duration of the IR and an increase in students' helping each other learn occurred more frequently when the mutual focus consisted of science‐related symbols, when there were low levels of risk for participants, when activities involved sufficient challenge and time, and when students were positioned as knowledgeable and competent in science. The results suggest that successful interaction rituals can foster student engagement with topics that may not have previously held interest and can contribute to students' support of peers' learning, thereby moving the classroom toward a community‐of‐practice model. © 2006 Wiley Periodicals, Inc. J Res Sci Teach
Debaryomyces hansenii — an extremophilic yeast with biotechnological potential
Authors: Breuer Uta , Harms Hauke
Published: May 2006

We illuminate the ecological, physiological and genetic characteristics of the yeast Debaryomyces hansenii in the view of our belief that this metabolically versatile, non‐pathogenic, osmotolerant and oleaginous microorganism represents an attractive target for fundamental and applied biotechnological research. To this end, we give a broad overview of extant biotechnological procedures using D. hansenii, e.g. in the manufacture of various foods, and propose research into the heterologous synthesis of a range of fine chemicals. Copyright © 2006 John Wiley & Sons, Ltd.
M[B(CN)4]2: Zwei neue Tetracyanoborate mit zweiwertigen Kationen (M = Zn, Cu)
Authors: Neukirch Michael , Tragl Sonja , Meyer H.‐Jürgen , Küppers Torsten , Willner Helge
Published: May 2006

M[B(CN)4]2: Two new Tetracyanoborate Compounds with divalent Cations (M = Zn, Cu)

The reaction of ZnO or CuO with [H3O][B(CN)4] in aqueous solution yielded single crystals of Zn[B(CN)4]2 and Cu[B(CN)4]2, respectively. The compounds were characterized by single‐crystal X‐ray diffraction. Zn[B(CN)4]2 ($P{\bar 3}m{\rm 1}$ (no. 164), a = b = 7.5092(9) Å, c = 6.0159(6) Å, Z = 1) crystallizes isotypic with Hg[B(CN)4]2. The structure of Cu[B(CN)4]2 (C2/m (no. 12), a = 13.185(3) Å, b = 7.2919(9) Å, c = 6.029(1) Å, β = 93.02(2)°, Z = 2) can be considered as a super‐structure, resulting from Jahn‐Teller distortion of the Cu2+ ions. Magnetic measurements were performed for the copper compound. Vibrational spectra and thermal stabilities were compared with the known mercury(II) tetracyanoborate.
Synthese und Kristallstruktur des Azidoberyllats (Ph4P)2[Be(μ‐OSiMe3)(N3)2]2
Authors: Neumüller Bernhard , Dehnicke Kurt
Published: May 2006

Synthesis and Crystal Structure of the Azido Beryllate (Ph4P)2[Be(μ‐OSiMe3)(N3)2]2

(Ph4P)2[Be2F6] reacts with excess trimethylsilylazide in acetonitrile solution, accompanied by a hydrolytic side‐reaction to give the azido beryllate (Ph4P)2[Be(μ‐OSiMe3)(N3)2]2 (1) as colourless, non‐explosive crystals. 1 was characterized by IR spectroscopy and by single crystal X‐ray determination.

1: Space group ${\rm P}{\bar 1}$, Z = 1, lattice dimensions at 193 K: a = 1026.9(1), b = 1184.0(1), c = 1352.1(1) pm, α = 73.50(1)°, β = 74.35(1)°, γ = 64.66(1)°, R1 = 0.0543. The complex anion of 1 forms centrosymmetric units with symmetry Ci via Be2O2 four‐membered rings with Be–O distances of 159.2(7) and 168.7(7) pm, and terminally bonded azide groups.
Die neuen Schichtsilicate Ba3Si6O9N4 und Eu3Si6O9N4
Authors: Stadler Florian , Schnick Wolfgang
Published: May 2006

The New Layer‐Silicates Ba3Si6O9N4 and Eu3Si6O9N4

The new oxonitridosilicate Ba3Si6O9N4 has been synthesized in a radiofrequency furnace starting from BaCO3, amorphous SiO2 and Si3N4. The reaction temperature was at about 1370 °C. The structure of the colorless compound has been determined by single‐crystal X‐ray diffraction analysis (Ba3Si6O9N4, space group P3 (no. 143), a = 724.9(1) pm, c = 678.4(2) pm, V = 308.69(9)· 106 pm3, Z = 1, R1 = 0.0309, 1312 independent reflections, 68 refined parameters). The compound is built up of corner sharing SiO2N2 tetrahedra forming corrugated layers between which the Ba2+ ions are located. Substitution of barium by europium leads to the isotypic compound Eu3Si6O9N4. Because no single‐crystals could be obtained, a Rietveld refinement of the powder diffractogram was conducted for the structure refinement (Eu3Si6O9N4, space group P3 (no. 143), a = 711.49(1) pm, c = 656.64(2) pm, V = 287.866(8) ·106 pm3, Rp = 0.0379, RF2 = 0.0638). The 29Si MAS‐NMR spectrum of Ba3Si6O9N4 shows two resonances at −64.1 and −66.0 ppm confirming two different crystallographic Si sites.
Die Reaktion von AlCl mit H2O in festem Argon: IR‐matrixspektroskopischer Nachweis von HAl(Cl)OH
Authors: Köppe R.
Published: May 2006

The Reaction of AlCl with H2O in Solid Argon: IR Matrixspectroscopic Detection of HAl(Cl)OH

After photolytical activation of AlCl and H2O in solid argon the molecule HAl(Cl)OH is formed. Structure and bonding is characterized by means of normal coordinate analysis and quantum chemical calculations. The complex AlCl···H2O formed directly after condensation serves as a model system for the stabilisation of aluminium monohalide in a mixture of toluene and ether.
Chemischer Transport fester Lösungen. 27. Mischphasenbildung und chemischer Transport im System ZnSe/GaAs
Authors: Brünig C. , Locmelis S. , Milke E. , Binnewies M.
Published: May 2006

Chemical Vapor Transport of Solid Solutions. 27. Formation of Solid Solutions and Chemical Vapor Transport in the System GaAs/ZnSe

The miscibility of ZnSe and GaAs as a function of temperature has been investigated. At temperatures above 1100 °C GaAs and ZnSe form out a continous crystalline solid solution. The phase diagram of this system is presented. Mixed crystals in the system GaAs/ZnSe can be prepared by means of chemical vapor transport using iodine as transport agent. Mass spectrometric investigations have shown the formation of AsSeI(g), an up to now unknown triatomic molecule. First approximate thermodynamic Data for AsSeI(g) are given. The knowledge of AsSeI and its thermodynamic stability is necessary to understand the transport phenomena.
Synthesis and Structure of Dicyclohexylammonium Tri‐tert‐pentoxysilanethiolate and 5‐Aminopentylammonium Tri‐tert‐pentoxysilanethiolate
Authors: Baranowska K. , Chojnacki J. , Gosiewska M. , Wojnowski W.
Published: May 2006

Tri–tert–pentoxysilanethiol, (EtMe2CO)3SiSH, reacts with dicyclohexylamine and 1,5–diaminopentane yielding ion‐quadruples connected by hydrogen bonds: [{(C6H11)2NH2}+{(EtMe2CO)3SiS}−]2 (1) and [{H2N–C5H10–NH3}+{(EtMe2CO)3SiS}−]2 (2). The compounds were characterized by X–ray diffraction, elemental analysis, IR and NMR. Both compounds form dimers, composed of two thiolate anions and two ammonium cations. The dimers have a central core of eight–membered rings built due to the formation of four charge–assisted N+–H···−S–hydrogen bonds. Additional N+–H···N hydrogen bonds are found in the case of 2, linking the dimers into infinite two–dimensional sheets.
Synthese eines funktionalen Aluminiumalkinids, Me3C‐C≡C‐AlBr2, und dessen Reaktionen mit der sperrigen Lithiumverbindung LiCH(SiMe3)2
Authors: Uhl Werner , Er Elif , Matar Madhat
Published: May 2006

Synthesis of a Functional Aluminium Alkynide, Me3C‐C≡C‐AlBr2, and its Reactions with the Bulky Lithium Compound LiCH(SiMe3)2

Treatment of aluminium tribromide with the lithium alkynide (Li)C≡C‐CMe3 afforded the aluminium alkynide Me3C‐C≡C‐AlBr2 (1) in an almost quantitative yield. 1 crystallizes with trimeric formula units possessing Al3C3 heterocycles and the anionic carbon atoms of the alkynido groups in the bridging positions. A dynamic equilibrium was determined in solution which probably comprises trimeric and dimeric formula units. Reaction of 1 with one equivalent of LiCH(SiMe3)2 yielded the compound [Me3C‐C≡C‐Al(Br)‐CH(SiMe3)2]2 (2), which is a dimer via Al‐C‐Al bridges. Two equivalents of the lithium compound gave a mixture of four main‐products, which could be identified as 2, Li[Me3C‐C≡C‐Al{CH(SiMe3)2}3] (3), Me3C‐C≡C‐Al[CH(SiMe3)2]2 (4), and Al[CH(SiMe3)2]3. The lithium atom of 3 is coordinated by the C≡C triple bond and an inner carbon atom of one bis(trimethylsilyl)methyl group. Further interactions were observed to C‐H bonds of methyl groups.
Altering the Activity of Catechol Oxidase Model Compounds by Electronic Influence on the Copper Core
Authors: Anekwe Johnson , Hammerschmidt Adrienne , Rompel Annette , Krebs Bernt
Published: May 2006

The catecholase activity of the dicopper(II) complexes [Cu2(L1)(μ‐OCH3)(NCCH3)2](PF6)2·H2O·CH3CN (1), [Cu2(L2)(μ‐OH)(MeOH)(NCCH3)](BF4)2 (2), [Cu2(L3)(μ‐OMe)(NCCH3)2](BF4)2·2CH3CN·H2O (3), [Cu2(L2)(μ‐OAc)2]BF4·H2O (4), [Cu2(L4)(μ‐OAc)2]ClO4 (5) and [Cu2(L5)(μ‐OMe)(NCCH3)3(OH2)](ClO4)2·2CH3OH·CH3CN (6) consisting of varying para‐substituted phenol ligands HL1 = 4‐trifluoromethyl‐2,6‐bis((4‐methylpiperazin‐1‐yl)methyl)phenol, HL2 = 4‐bromo‐2,6‐bis((4‐methyl‐1,4‐diazepan‐1‐yl)methyl)phenol, HL3 = 4‐bromo‐2‐((4‐methyl‐1,4‐diazepan‐1‐yl)methyl)‐6‐((4‐methylpiperazin‐1‐yl)methyl)phenol, HL4 = 2,6‐bis((4‐methylpiperazin‐1‐yl)methyl)‐4‐nitrophenol and HL5 = 4‐tert‐butyl‐2,6‐bis((4‐methylpiperazin‐1‐yl)methyl)phenol was studied. The main difference within the six complexes lies in the individual copper–copper separation that is enforced by the chelating side arms of the phenolate ligand entity and more importantly in the exogenous bridging solvent, hydroxide, methanolate or acetate ions. The distance between the copper cores varies from 2.94Å in 1 to 3.29Å in 5. The catalytic activity of the complexes 1–6 towards the oxidation of 3,5‐di‐tert‐butylcatechol was determined spectrophotometrically by monitoring the increase of the 3,5–di‐tert‐butylquinone characteristic absorption band at about 400 nm over time saturated with O2. The complexes are able to oxidize the substrate 3,5‐di‐tert‐butylcatechol to the corresponding o‐quinone with distinct catalytic activity (kcat between 92 h−1 and 189 h−1), with an order of decreasing activity 6 > 5 > 1, 2, 4 ≥ 3. A kinetic treatment of the data based on the Michaelis‐Menten approach was applied. A correlation of the catecholase activities with the variation of the para‐ substituents as well as other effects resulting from the copper core distances is discussed. [Cu2(L5)(μ‐OMe)(NCCH3)3(OH)2](ClO4)2·2CH3OH·CH3CN (6) exhibited the highest activity of the six complexes as a result of its high turnover rate.
The structure of PknB in complex with mitoxantrone, an ATP‐competitive inhibitor, suggests a mode of protein kinase regulation in mycobacteria
Authors: Wehenkel Annemarie , Fernandez Pablo , Bellinzoni Marco , Catherinot Vincent , Barilone Nathalie , Labesse Gilles , Jackson Mary , Alzari Pedro M.
Published: May 2006

Mycobacterium tuberculosis PknB is an essential receptor‐like protein kinase involved in cell growth control. Here, we demonstrate that mitoxantrone, an anthraquinone derivative used in cancer therapy, is a PknB inhibitor capable of preventing mycobacterial growth. The structure of the complex reveals that mitoxantrone partially occupies the adenine‐binding pocket in PknB, providing a framework for the design of compounds with potential therapeutic applications. PknB crystallizes as a ‘back‐to‐back’ homodimer identical to those observed in other structures of PknB in complex with ATP analogs. This organization resembles that of the RNA‐dependent protein kinase PKR, suggesting a mechanism for kinase activation in mycobacteria.
A novel retinoid binding property of human annexin A6
Authors: Balcerzak Marcin , Bandorowicz-Pikula Joanna , Buchet Rene , Pikula Slawomir
Published: May 2006

Vitamin A (all‐trans retinol) and all‐trans retinoid acid (ATRA) interacted with human annexin A6 (AnxA6) as evidenced by AnxA6‐induced blue shift of retinoid absorption maxima, by AnxA6‐Trp fluorescence quenching and by a fluorescence resonance energy transfer from a Trp residue of AnxA6 to retinol. In addition, both retinoids stimulated the calcium‐dependent binding of AnxA6 to liposomes, accompanied by oligomerization of AnxA6. Up to our knowledge, it is a first report supporting the hypothesis of a direct implication of AnxA6 in vitamin A‐dependent tissue mineralization.
Identification and characterization of human cardiolipin synthase
Authors: Houtkooper Riekelt H. , Akbari Hana , van Lenthe Henk , Kulik Willem , Wanders Ronald J.A. , Frentzen Margrit , Vaz Frédéric M.
Published: May 2006

The mitochondrial phospholipid cardiolipin is synthesized from cytidinediphosphate‐diacylglycerol and phosphatidylglycerol, a process catalyzed by the enzyme cardiolipin synthase. In this study, we identified a human candidate gene/cDNA for cardiolipin synthase, C20orf155. Expression of this candidate cDNA in the (cardiolipin synthase‐deficient) crd1Δ yeast confirmed that it indeed encodes human cardiolipin synthase. Purified mitochondria of the crd1Δ expressing human cardiolipin synthase were used to characterize the enzyme. It has an alkaline pH optimum, requires divalent cations for activity and appears to have a different substrate preference for cytidinediphosphate‐diacylglycerol species when compared to phosphatidylglycerol species. The possible implications for CL synthesis and remodeling are discussed.
Heat shock proteins reduce α‐synuclein aggregation induced by MPP+ in SK‐N‐SH cells
Authors: Fan Guo-Hua , Zhou Hai-Yan , Yang Hui , Chen Sheng-Di
Published: May 2006

α‐Synuclein has been implicated in the pathogenesis of Parkinson's disease (PD). Heat shock proteins (HSPs) can reduce protein misfolding and accelerate the degradation of misfolded proteins. 1‐methyl‐4‐phenylpyridinium ion (MPP+) is the compound responsible for the PD‐like neurodegeneration caused by MPTP. In this study, we found that MPP+ could increase the expression of α‐synuclein mRNA but could not elevate proteasome activity sufficiently, leading to α‐synuclein protein accumulation followed by aggregation. Both HSPs and HDJ‐1, a homologue of human Hsp40, can inhibit MPP+‐induced α‐synuclein mRNA expression, promote ubiquitination and elevate proteasome activity. These findings suggest that HSPs may inhibit the MPP+‐induced α‐synuclein expression, accelerate α‐synuclein degradation, thereby reducing the amount of α‐synuclein protein and accordingly preventing its aggregation.
The transmembrane domain provides nucleotide binding specificity to the bacterial conjugation protein TrwB
Authors: Hormaeche Itsaso , Segura Rosa L. , Vecino Ana J. , Goñi Félix M. , de la Cruz Fernando , Alkorta Itziar
Published: May 2006

In order to understand the functional significance of the transmembrane domain of TrwB, an integral membrane protein involved in bacterial conjugation, the protein was purified in the native, and also as a truncated soluble form (TrwBΔN70). The intact protein (TrwB) binds preferentially purine over pyrimidine nucleotides, NTPs over NDPs, and ribo‐ over deoxyribonucleotides. In contrast, TrwBΔN70 binds uniformly all tested nucleotides. The transmembrane domain has the general effect of making the nucleotide binding site(s) less accessible, but more selective. This is in contrast to other membrane proteins in which most of the protein mass, including the catalytic domain, is outside the membrane, but whose activity is not modified by the presence or absence of the transmembrane segment.
Intimate Partner Violence Screening Practices of Certified Nurse‐Midwives
Authors: Hindin Patricia K.
Published: May 2006

It is estimated that 324,000 pregnant women are abused by their partners in the United States each year. The purpose of this qualitative study was to explore the intimate partner violence‐screening practices of certified nurse‐midwives (CNMs). In‐depth interviews were conducted with a sample (n = 8) of CNMs, and the data were analyzed by using with‐case and across‐case methods. The findings demonstrate that the midwives were inconsistent in their intimate partner violence‐screening practice during pregnancy and increase or decrease screening in response to a woman's cultural background. Screening in a culturally competent manner is expected of all clinicians, but the demands of an increasingly complex, culturally diverse practice environment make it difficult. Consistent intimate partner abuse screening in a culturally competent manner is a challenge for all primary care providers.
Assessing and Managing Women With Depression: A Midwifery Perspective
Authors: Sanders Lorraine B.
Published: May 2006

Women are at disproportionate risk for depression. Depression often goes untreated because of lack of recognition by providers. The Institute of Medicine maintains that primary care providers are essential in the management of mental health disorders. The assessment and management of depression in women are sensitive topics and may require advanced training and skills.
Perceptions and Use of Smoking Cessation in Nurse‐Midwives' Practice
Authors: Price James H. , Jordan Timothy R. , Dake Joseph A.
Published: May 2006

The objective of this study was to examine Ohio nurse‐midwives' perceptions and use of a smoking cessation protocol in assisting pregnant smokers. The total population of licensed Ohio nurse‐midwives (n = 300) was surveyed by using a cross‐sectional survey design. Only 4 of 10 items that assessed a nationally recommended method of promoting smoking cessation were done by 50% or more of respondents. Few nurse‐midwives identified barriers to counseling pregnant patients who smoked, but the most common were lack of time (14%) and not knowing where to send pregnant smokers for treatment (14%). Most respondents believed that nicotine replacement therapy (NRT) would be most likely to reduce the number of pregnant smokers (74%), yet few (26%) were confident in their ability to prescribe/recommend nicotine replacement therapy. Respondents more likely to use 5A's can be characterized as the following: had higher efficacy expectations in their ability to communicate issues about the 5A's and had higher outcome expectations regarding the effects of using the 5A's. Nurse‐midwife training programs and continuing education needs to include current research in nicotine replacement therapy use in pregnant patients and 5A's techniques to assist pregnant smokers in quitting.
Management of Migraine Headaches
Authors: Graves Barbara W.
Published: May 2006

With 17% to 18% of women suffering from migraine headaches, clinicians will often be asked by their patients to prescribe medication. Migraine is an episodic chronic disease that is best managed with an overall treatment plan, rather than treated as an acute illness that is managed with sporadic medications. Realistic goals for the long‐term management of migraine are based on patient education and an ongoing discussion between patient and provider. This article reviews the clinical presentation of migraine and recommendations for both acute and preventive treatment, including complementary therapies. “Red flags” that could be signs of more serious neurologic illness are presented. The management of migraine in pregnancy is also reviewed.
Selling Sickness: How the World's Biggest Pharmaceutical Companies Are Turning Us All Into Patients
Authors: Walsh Linda V.
Published: May 2006

By Ray Moynihan and Alan Cassels. New York: Nation Books, 2005. 245 pages. $25.00, hardcover.
Primary Health Care by Midwives: Comprehensive and Competent Health Services for Women
Authors: Shah Mary Ann , King Tekoa L.
Published: May 2006

The concept of primary care … cuts across all disciplines within the medical profession and across other professions, such as nursing, midwifery, and social work. Health care providers must articulate what the shared content of primary care is so that they can meet their obligation to society: improving the health of all persons.1
Stapedectomy in Congenital Stapes Fixation: Are Hearing Outcomes Poorer?
Authors: Massey Becky L. , Hillman Todd A. , Shelton Clough
Published: May 2006

OBJECTIVE

To evaluate outcomes of stapedectomy surgery for congenital stapes fixation.

STUDY DESIGN

Retrospective chart review.

METHODS

The charts of 463 stapedectomies performed by 1 surgeon from 1996 to 2003 were reviewed. Patients with a history of childhood hearing loss and operative findings consistent with congenital fixation of the stapes were included. Patients with a history of trauma or chronic otitis media and those with otosclerosis were excluded. Thirty‐six patients underwent stapedectomy for congenital fixation. Revision cases and those with inadequate postoperative bone or air conduction data were excluded. Inclusion criteria were met for 25 patients. Operative findings and hearing outcomes were evaluated.

RESULTS

The study group was comprised of 25 stapedectomies. Closure of the air‐bone gap to less than 10 dB was achieved in 48% of cases, and 80% had closure within 20 dB. A gap of more than 30 dB remained in 3 cases. There were 2 cases of sensorineural hearing loss with worsening of the bone conduction thresholds by 15 dB and 30 dB. There were no instances of perilymph gusher. In addition to an excluded case that was not reconstructed because of facial nerve position, 3 of the included patients were found to have a dehiscent facial nerve at surgery. There were no facial nerve injuries, and fixation of the malleus or incus was not found in any of the included patients. When hearing outcomes were compared with our results for otosclerosis over the same time period, rates of closure to within 10 dB and 20 dB were significantly worse in the congenital group.

CONCLUSION

Closure of the air‐bone gap in this population differs from our results in stapedectomy done for otosclerosis. This difference likely reflects subtle anatomic variations in the congenital group that affect the effectiveness of the prosthesis. Despite the difference in results, stapedectomy for congenital fixation remains an effective method to achieve significant hearing improvement in the majority of patients.

EBM rating: B‐3b
CT‐MR Image Fusion for the Management of Skull Base Lesions
Authors: Leong Jern‐Lin , Batra Pete S. , Citardi Martin J.
Published: May 2006

OBJECTIVE

Image fusion software creates composite images from computed tomography (CT) and magnetic resonance (MR) images.

STUDY DESIGN AND SETTING

CT‐MR fusion studies between August 2004 to July 2005 were reviewed. CT scan images (1‐mm axial) were obtained on a multi‐detector CT scanner. MR images (1‐mm axial) were obtained with a T1‐weighted, volume acquisition technique. CT‐MR fusion images were created on the Instatrak 3500 Plus or CBYON Suite.

RESULTS

A total of 25 patients had 27 CT‐MR image fusion studies. CT‐MR fusion accuracy was 2 mm or better. During preoperative planning and intraoperative navigation, CT‐MR fusion facilitated the delineation of the anatomic relationships between the lesion and the skull base.

CONCLUSIONS

CT‐MR image fusion yields composite images that combine features of each component imaging modality. Image fusion, when combined with surgical navigation, further enhances potential skull base applications for minimally invasive endoscopic surgery.
Intraoperative Cone‐beam CT for Guidance of Temporal Bone Surgery
Authors: Rafferty Mark A. , Siewerdsen Jeffrey H. , Chan Yvonne , Daly Michael J. , Moseley Douglas J. , Jaffray David A. , Irish Jonathan C.
Published: May 2006

OBJECTIVES

To describe our preclinical experience with Cone Beam CT (CBCT) in image‐guided surgery of the temporal bone.

STUDY DESIGN AND SETTINGS

A mobile isocentric C‐arm (PowerMobil, Siemens Medical Systems, Erlangen, Germany) modified to include a flat‐panel detector (Varian Imaging Products, Palo Alto, CA) and a motorized orbit was developed to acquire multiple projections in rotation about a subject. Initial experiments imaging steel wire in air were used to investigate the system's spatial resolution in 3D image reconstruction. Subsequently temporal bone dissection was performed on five cadaver heads using the modified C‐arm as an image guidance system.

RESULTS

We obtained a spatial resolution of 0.85 mm. The image acquisition time was 120 seconds and the radiation dose approximately one‐tenth of a conventional CT scan.

CONCLUSION

CBCT provided submillimeter accuracy at high speed with low radiation dosage to offer utility as an intraoperative imaging system.

SIGNIFICANCE

CBCT offers technology that approximates “near‐real‐time” image guidance.

EBM rating: C‐4
Gerbilline Cholesteatoma Development Part I: Epithelial Migration Pattern and Rate on the Gerbil Tympanic Membrane: Comparisons with Human and Guinea Pig
Authors: Tinling Steven P. , Chole Richard A.
Published: May 2006

OBJECTIVE

To determine the migration rate and pattern for keratin on the tympanic membrane (TM) of the gerbil and guinea pig in comparison to human data and determine which species is an appropriate model for investigating the relationship of epithelial clearance to cholesteatoma formation.

STUDY DESIGN AND SETTING

Ink drops were placed on the TM and their locations plotted daily.

RESULTS

Gerbils demonstrated a radial migration pattern away from the umbo, identical to that reported for humans, although the rate was 0.32 mm/day—3 times the human rate of 0.1 mm/day. Guinea pigs were significantly different from gerbils and humans, with a rate of 0.79 mm/day and a pattern of superior/inferior migration without anterior‐posterior movement.

CONCLUSION

Gerbils more closely resemble humans in rate and pattern of epithelial migration.

SIGNIFICANCE

Gerbils represent the most appropriate model for determining the relationship between keratin migration and cholesteatoma formation.