bluuebunny/crossref_metadata_2025 huggingface dataset:
Pentacoordination at Germanium by Transannular Bonding of Sulfur or Oxygen in an Eight‐Membered Ring: An Experimental and Theoretical Study
Authors: González‐Montiel Simplicio , Andrade‐López Noemí , García‐Montalvo Verónica , Cogordan Juan Antonio , Alvarado‐Rodríguez José G.
Published: October 2006

Treatment of LnGeCl4–n with D(C6H4SH)2 in the presence of nBuLi leads to the formation of the stable compounds D(C6H4S)2GeL1L2 (for D = S, L1 = Cl, L2 = Ph, 1 and L1 = L2 = Ph, 3; for D = O, L1 = Cl, L2 = Et, 4 and L1 = L2 = Ph, 5). The S(C6H4S)2Ge(Ph)Br compound (2) has been synthesised by halogen exchange from 1 and potassium bromide. X‐ray structure determinations of complexes 1–5 reveal that the germanium atom acts as an acceptor atom displaying an intramolecular transannular interaction with the chalcogen D atom. The geometry of the pentacoordinate Ge atom in the title compounds is described as distorted trigonal bipyramidal with a 64–31 % distortion displacement. The D→Ge (D = S, O) hypercoordinate interaction was studied by DFT methods using correlation consistent basis sets and relativistic ECP for Ge. NBO analysis showed that this interaction can be explained in terms of the interplay of covalent and Coulombic interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A Facile Hydrothermal Route to Flower‐Like Cobalt Hydroxide and Oxide
Authors: Yang Li‐Xia , Zhu Ying‐Jie , Li Liang , Zhang Ling , Tong Hua , Wang Wei‐Wei , Cheng Guo‐Feng , Zhu Jie‐Fang
Published: October 2006

Flower‐like cobalt hydroxide [β‐Co(OH)2] consisting of nanosheet networks has been synthesized by a hydrothermal method from Co(CH3COO)2·4H2O in mixtures of water and glycerol/ethylene glycol at 200 °C. The morphology and phase of the cobalt hydroxide can be controlled by adjusting the experimental parameters that include cobalt acetate concentration and the volume ratio of water to glycerol/ethylene glycol. The possible formation mechanism of flower‐like cobalt hydroxide is discussed on the basis of experimental results. Cobalt oxide (Co3O4) flowers have also been obtained by thermal decomposition of cobalt hydroxide flowers in air at 400 °C. The products were characterized by powder XRD, TEM, selected‐area electron diffraction (SAED), high resolution TEM (HRTEM), and field‐emission SEM (FESEM). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Nickel Thiolate Complexes as Ligands for Copper and Zinc: Novel Additions to a Library of Binding Modes
Authors: Verhagen Johanna A. W. , Tock Christian , Lutz Martin , Spek Anthony L. , Bouwman Elisabeth
Published: October 2006

The reactivity of the two nickel complexes [Ni(xbsms)] and [Ni(bsms)2] [H2xbsms = α,α′‐bis(4‐mercapto‐3,3‐dimethyl‐2‐thiabutyl)‐o‐xylene; Hbsms = 4‐mercapto‐3,3‐dimethyl‐1‐phenyl‐2‐thiabutane] towards copper iodide and zinc bromide has been investigated. The reactions yield novel aggregates of higher nuclearity with topologies that are different from previous reports; the nickel complexes in all cases can be considered as didentate S ligands. The X‐ray structure of the novel octanuclear cluster [{Ni(bsms)2}3(CuI)5] shows a unique arrangement in which the cis‐NiS2S′2 units act as didentate ligands to a trigonal‐bipyramidal array of five CuI ions. The tetranuclear structure of [{Ni(xbsms)CuI}2] shows unprecedented asymmetric bridging of the thiolate sulfur atoms, with one of the thiolate groups binding to one copper ion and the other one μ3‐bridging to two copper ions. The complex is located on a crystallographic twofold axis and the complex in a single crystal is enantiomerically pure. The trinuclear complex [Ni2(bsms)3ZnBr3] is formed as a result of dissociation of the didentate bsms ligand from part of the mononuclear complex and reassembly to form a dinuclear core to which the ZnBr3– unit is coordinated to a single thiolate sulfur atom. A complex of stoichiometry [Ni3(xbsms)2(ZnBr3)2] has also been isolated and a structure proposal based on spectroscopic properties is given. All complexes have been characterised by analytical and spectroscopic methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Highly Diastereoselective [3+2] Cyclopenta[b]annulation of Indoles with2‐Arylcyclopropyl Ketones and Diesters
Authors: Venkatesh Chelvam , Singh Prabal P. , Ila Hiriyakkanavar , Junjappa Hiriyakkanavar
Published: October 2006

A highly diastereoselective Lewis acid (BF3·Et2O or TiCl4) induced [3+2] cycloaddition of substituted and unsubstituted indoles with 2‐arylcyclopropyl ketones/diesters yielding cyclopenta[b]indoles in high yields is reported. This methodology has also been extended to tetrahydrocarbazole, cyclopenta[b]‐ and cyclohepta[b]indoles affording tetracyclic propellane type frameworks in modest yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Reactions of Alkenyl Fischer Carbene Complexes with Ketene Acetals: Formation of Alkynes
Authors: Wang Siu Ling B. , Liu Xuejun , Ruiz Miriam C. , Gopalsamuthiram Vijay , Wulff William D.
Published: October 2006

Alkenyl Fischer carbene complexes with an isopropoxy group on the carbene carbon will react with ketene acetals by 1,4‐addition to give a zwitterionic intermediate, which undergoes subsequent internal isopropoxide transfer to generate a vinylidene complex. Either a hydrogen or phenyl group on the vinylidene carbon will undergo a formal 1,2‐migration to give 4‐pentynoate esters after hydrolysis of the intermediate orthoester. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A fourth‐order compact finite volume scheme for fully nonlinear and weakly dispersive Boussinesq‐type equations. Part II: boundary conditions and validation
Authors: Cienfuegos R. , Barthélemy E. , Bonneton P.
Published: October 2006

This paper supplements the validation of the fourth‐order compact finite volume Boussinesq‐type model presented by Cienfuegos et al. (Int. J. Numer. Meth. Fluids 2006, in press). We discuss several issues related to the application of the model for realistic wave propagation problems where boundary conditions and uneven bathymetries must be considered. We implement a moving shoreline boundary condition following the lines given by Lynett et al. (Coastal Eng. 2002; 46:89–107), while an absorbing‐generating seaward boundary and an impermeable vertical wall boundary are approximated using a characteristic decomposition of the Serre equations. Using several benchmark tests, both numerical and experimental, we show that the new finite volume model is able to correctly describe nonlinear wave processes from shallow waters and up to wavelengths which correspond to the theoretical deep water limit. The results compare favourably with those reported using former fully nonlinear and weakly dispersive Boussinesq‐type solvers even when time integration is conducted with Courant numbers greater than 1.0. Furthermore, excellent nonlinear performance is observed when numerical computations are compared with several experimental tests on solitary waves shoaling over planar beaches up to breaking. A preliminary test including the wave‐breaking parameterization described by Cienfuegos (Fifth International Symposium on Ocean Wave Measurement Analysis, Madrid, Spain, 2005) shows that the Boussinesq model can be extended to deal with surf zone waves. Finally, practical aspects related to the application of a high‐order implicit filter as given by Gaitonde et al. (Int. J. Numer. Methods Engng 1999; 45:1849–1869) to damp out unphysical wavelengths, and the numerical robustness of the finite volume scheme are also discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Comparison of adjoint‐based and feature‐based grid adaptation for functional outputs
Authors: Balasubramanian R. , Newman J. C.
Published: October 2006

Adjoint‐based and feature‐based grid adaptive strategies are compared for their robustness and effectiveness in improving the accuracy of functional outputs such as lift and drag coefficients. The output‐based adjoint approach strives to improve the adjoint error estimates that relate the local residual errors to the global error in an output function via adjoint variables as weight functions. A conservative adaptive indicator that takes into account the residual errors in both the primal (flow) and dual (adjoint) solutions is implemented for the adjoint approach. The physics‐based feature approach strives to identify and resolve significant features of the flow to improve functional accuracy. Adaptive indicators that represent expansions and compressions in the flow direction and gradients normal to the flow direction are implemented for the feature approach. The adaptive approaches are compared for functional outputs of three‐dimensional arbitrary Mach number flow simulations on mixed‐element unstructured meshes. Grid adaptation is performed with h‐refinement and results are presented for inviscid, laminar and turbulent flows. Copyright © 2006 John Wiley & Sons, Ltd.
A reduced‐order approach to four‐dimensional variational data assimilation using proper orthogonal decomposition
Authors: Cao Yanhua , Zhu Jiang , Navon I. M. , Luo Zhendong
Published: October 2006

Four‐dimensional variational data assimilation (4DVAR) is a powerful tool for data assimilation in meteorology and oceanography. However, a major hurdle in use of 4DVAR for realistic general circulation models is the dimension of the control space (generally equal to the size of the model state variable and typically of order 107–108) and the high computational cost in computing the cost function and its gradient that require integration model and its adjoint model.

In this paper, we propose a 4DVAR approach based on proper orthogonal decomposition (POD). POD is an efficient way to carry out reduced order modelling by identifying the few most energetic modes in a sequence of snapshots from a time‐dependent system, and providing a means of obtaining a low‐dimensional description of the system's dynamics. The POD‐based 4DVAR not only reduces the dimension of control space, but also reduces the size of dynamical model, both in dramatic ways. The novelty of our approach also consists in the inclusion of adaptability, applied when in the process of iterative control the new control variables depart significantly from the ones on which the POD model was based upon. In addition, these approaches also allow to conveniently constructing the adjoint model.

The proposed POD‐based 4DVAR methods are tested and demonstrated using a reduced gravity wave ocean model in Pacific domain in the context of identical twin data assimilation experiments. A comparison with data assimilation experiments in the full model space shows that with an appropriate selection of the basis functions the optimization in the POD space is able to provide accurate results at a reduced computational cost. The POD‐based 4DVAR methods have the potential to approximate the performance of full order 4DVAR with less than 1/100 computer time of the full order 4DVAR. The HFTN (Hessian‐free truncated‐Newton)algorithm benefits most from the order reduction (see (Int. J. Numer. Meth. Fluids, in press)) since computational savings are achieved both in the outer and inner iterations of this method. Copyright © 2006 John Wiley & Sons, Ltd.
A numerical strategy for modelling rotating stall in core compressors
Authors: Vahdati M.
Published: October 2006

The paper will focus on one specific core‐compressor instability, rotating stall, because of the pressing industrial need to improve current design methods. The determination of the blade response during rotating stall is a difficult problem for which there is no reliable procedure. During rotating stall, the blades encounter the stall cells and the excitation depends on the number, size, exact shape and rotational speed of these cells. The long‐term aim is to minimize the forced response due to rotating stall excitation by avoiding potential matches between the vibration modes and the rotating stall pattern characteristics. Accurate numerical simulations of core‐compressor rotating stall phenomena require the modelling of a large number of bladerows using grids containing several tens of millions of points. The time‐accurate unsteady‐flow computations may need to be run for several engine revolutions for rotating stall to get initiated and many more before it is fully developed. The difficulty in rotating stall initiation arises from a lack of representation of the triggering disturbances which are inherently present in aeroengines. Since the numerical model represents a symmetric assembly, the only random mechanism for rotating stall initiation is provided by numerical round‐off errors. In this work, rotating stall is initiated by introducing a small amount of geometric mistuning to the rotor blades. Another major obstacle in modelling flows near stall is the specification of appropriate upstream and downstream boundary conditions. Obtaining reliable boundary conditions for such flows can be very difficult. In the present study, the low‐pressure compression (LPC) domain is placed upstream of the core compressor. With such an approach, only far field atmospheric boundary conditions are specified which are obtained from aircraft speed and altitude. A chocked variable‐area nozzle, placed after the last compressor bladerow in the model, is used to impose boundary conditions downstream. Such an approach is representative of modelling an engine.

Using a 3D viscous time‐accurate flow representation, the front bladerows of a core compressor were modelled in a whole‐annulus fashion whereas the rest of bladerows are modelled in a single‐passage fashion. The rotating stall behaviour at two different compressor operating points was studied by considering two different variable‐vane scheduling conditions for which experimental data were available. Using a model with nine whole‐assembly models, the unsteady‐flow calculations were conducted on 32‐CPUs of a parallel cluster, typical run times being around 3–4 weeks for a grid with about 60 million points. The simulations were conducted over several engine rotations. As observed on the actual development engine, there was no rotating stall for the first scheduling condition while mal‐scheduling of the stator vanes created a 12‐band rotating stall which excited the 1st flap mode. Copyright © 2006 John Wiley & Sons, Ltd.
Hybrid lattice Boltzmann finite‐difference simulation of axisymmetric swirling and rotating flows
Authors: Huang Haibo , Lee T. S. , Shu C.
Published: October 2006

The axisymmetric flows with swirl or rotation were solved by a hybrid scheme with lattice Boltzmann method for the axial and radial velocities and finite‐difference method for the azimuthal (or swirl) velocity and the temperature. An incompressible axisymmetric lattice Boltzmann D2Q9 model was proposed to solve the axial and radial velocities through inserting source terms into the two‐dimensional lattice Boltzmann equation. Present hybrid scheme was firstly validated by simulations of Taylor–Couette flows between two concentric cylinders. Then the benchmark problems of melt flow in Czochralski crystal growth were studied and accurate results were obtained. Numerical experiment demonstrated that present axisymmetric D2Q9 model is more stable than the previous axisymmetric D2Q9 model (J. Comp. Phys. 2003; 186(1):295–307). Hence, compared with the previous model, present numerical method provides a significant advantage in simulation melt flow cases with high Reynolds number and high Grashof number. Copyright © 2006 John Wiley & Sons, Ltd.
Accelerating aging of zirconia femoral head implants: Change of surface structure and mechanical properties
Authors: Chowdhury S. , Vohra Yogesh K. , Lemons Jack E. , Ueno Masaru , Ikeda Junji
Published: October 2006

Recently, alternations of zirconia ceramic femoral heads of total hip prostheses during in vivo conditions have caused concern in the medical disciplines regarding phase transformation of zirconia prosthetic components. In this paper, we have investigated the mechanical and structural properties of different laboratory aged zirconia femoral heads and correlated changes in mechanical properties with the phase compositions of the sample. From laser microscope observation, cross‐sectional Scanning electron microscopy imaging, and X‐ray diffraction analysis on the surface of the zirconia femoral heads, we found monoclinic to tetragonal phase transformation in zirconia prostheses over time during the aging process in the laboratory. Mechanical properties, mainly hardness (H) and Young's modulus (E) values, were measured by nanoindentation technique on the surface of these implants. The results showed that both H and E values decreased with increased monoclinic phase in zirconia, thus confirming a phase transformation over time during aging. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Evaluation of bone regeneration at critical‐sized calvarial defect by DBM/AM composite
Authors: Qiu Qing‐Qing , Mendenhall H. Vince , Garlick David S. , Connor Jerome
Published: October 2006

This study investigated the bone‐regenerative potential of a demineralized bone and acellular matrix (DBM/AM) composite (AlloCraft™ DBM) in comparison with autologous bone using an in vivo model. Critical‐sized calvarial defects (5 mm) were created in athymic rats. The defects were grafted with either the DBM/AM composite or the acellular human dermal matrix (AM), and compared with the defects filled with autologous bone (positive control) and the empty defect (negative control). Histological and radiographic assessments were carried out at 4 and 8 weeks after surgery to determine the biological healing, the amount and type of new bone formation and the percentage of new bone filled in the critical defects. At 4 weeks, DBM/AM composite group had the highest percentage of the defect filled with new bone (84%), which was significantly greater than autologous bone (62%), AM (41%), and untreated control (32%) groups. At 8 weeks, the DBM/AM continued to have the highest percentage of the defect filled with new bone (91%). The autologous bone group increased the percentage of bone fill to 83%. The defects either filled with AM or left untreated still had less of the defect filled with new bone, 57% and 33%, respectively. The total healing of defects grafted with DBM/AM was comparable with autologous bone group at 8 weeks. The results demonstrated that the DBM/AM composite promoted new bone formation more rapidly than autologous bone at calvarial defect in athymic rats. The study supports that DBM/AM is a potential substitute of autologous bone for bone repair. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Influence of changes in the composition of an acrylic bone cement on its polymerization kinetics
Authors: Lewis Gladius , Mishra Sanjay R.
Published: October 2006

It has been suggested in the literature that a lower polymerization rate of an acrylic bone cement is favorable for the in vivo longevity of a cemented arthroplasty. The present work was a study of the influence of three changes in the composition of an acrylic bone cement (when taken separately) on the cement polymerization rate at 37°C (assumed to be the temperature in the bone bed during a cemented arthroplasty) [k′]. The changes were the amount of copolymer as a proportion of the total powder weight (in cements in which there is a copolymer in the powder), the amount of DMPT as a proportion of the total volume of the liquid monomer, and the accelerator. k′ was calculated using values of the activation energy and the frequency factor (assuming the polymerization reaction is Arrhenius in nature) that were computed from measurements made using the nonisothermal mode of differential scanning calorimetry. Statistical analysis (one‐way ANOVA, with Bonferroni correction, and factorial ANOVA) of the k′ values showed that the change in accelerator had a significant influence on k′. The importance of this finding, together with results from two relevant literature reports, is discussed within the context of the use of modified bone cements in cemented arthroplasties. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Diatropicity of tetraazanaphthalenes
Authors: Cuesta I. García , de Merás A. Sánchez , Lazzeretti P.
Published: October 2006

Tetraazanaphthalenes are diatropic molecules, whose magnetic response to a magnetic field perpendicular to the molecular plane closely resembles that of naphthalene. The out‐of‐plane component of the magnetic susceptibility tensor and its strong anisotropy can be used as quantifiers of magnetic aromaticity. Maps showing streamlines and modulus of the current density field provide clear evidence for diatropicity of these systems. They also explain the strong anisotropy of carbon and nitrogen magnetic shielding, which is determined by the big out‐of‐plane component of the nuclear shielding tensor. The electronic ring currents observed in the map deshield the nuclei of ring hydrogens by enforcing the local magnetic field and diminishing the out‐of‐plane component of proton shielding. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006
Indian summer monsoon rainfall and its link with ENSO and Indian Ocean climate indices
Authors: Ihara Chie , Kushnir Yochanan , Cane Mark A. , De La Peña Victor H.
Published: October 2006

We examine the relationship between the state of the equatorial Indian Ocean, ENSO, and the Indian summer monsoon rainfall using data from 1881 to 1998. The zonal wind anomalies and SST anomaly gradient over the equatorial Indian Ocean are used as indices that represent the condition of the Indian Ocean. Although the index defined by the zonal wind anomalies correlates poorly with Indian summer monsoon rainfall, the linear reconstruction of Indian summer monsoon rainfall on the basis of a multiple regression from the NINO3 and this wind index better specifies the Indian summer monsoon rainfall than the regression with only NINO3. Using contingency tables, we find that the negative association between the categories of Indian summer monsoon rainfall and the wind index is significant during warm years (El Niño) but not during cold years (La Niña). Composite maps of land precipitation also indicate that this relationship is significant during El Niño events. We conclude that there is a significant negative association between Indian summer monsoon rainfall and the zonal wind anomalies over the equatorial Indian Ocean during El Niño events. A similar investigation of the relationship between the SST index and Indian summer monsoon rainfall does not reveal a significant association. Copyright © 2006 Royal Meteorological Society.
Electrical stimulation based on chronaxie reduces atrogin‐1 and myoD gene expressions in denervated rat muscle
Authors: Russo Thiago Luiz , Peviani Sabrina Messa , Freria Camila Marques , Gigo‐Benato Davilene , Geuna Stefano , Salvini Tania Fátima
Published: October 2006

Denervation induces muscle fiber atrophy and changes in the gene expression rates of skeletal muscle. Electrical stimulation (ES) is a procedure generally used to treat denervated muscles in humans. This study evaluated the effect of ES based on chronaxie and rheobase on the expression of the myoD and atrogin‐1 genes in denervated tibialis anterior (TA) muscle of Wistar rats. Five groups were examined: (1) denervated (D); (2) D+ES; (3) sham denervation; (4) normal (N); and (5) N+ES. Twenty muscle contractions were stimulated every 48 h using surface electrodes. After 28 days, ES significantly decreased the expression of myoD and atrogin‐1 in D+ES compared to the D group. However, ES did not prevent muscle‐fiber atrophy after denervation. Thus, ES based on chronaxie values and applied to denervated muscles using surface electrodes, as normally used in human rehabilitation, was able to reduce the myoD and atrogin‐1 gene expressions, which are related to muscular growth and atrophy, respectively. The results of this study provide new information for the treatment of denervated skeletal muscle using surface ES. Muscle Nerve, 2006
Stress urinary incontinence as the presenting symptom of primary male urethral diverticulum—A case report and literature review
Authors: Wang Shao‐Chuan , Lin Alex T.L. , Chen Kuang‐Kuo
Published: October 2006

Primary male urethral diverticulum is quite uncommon. It is even more unusual for urinary incontinence to be a presenting symptom of primary male urethral diverticulum. Herein, we report on a 32‐year‐old male presenting with urine leakage on coughing or abdominal strain beginning from his early twenties. A congenital type bulbar urethral diverticulum is diagnosed by voiding cystourethrography and cystourethroscopy. Endoscopic unroofing of the diverticulum freed the patient from stress urinary incontinence after the surgery. Neurourol. Urodynam. 26:271–273, 2007. © 2006 Wiley‐Liss, Inc.
Complexity of free energy landscapes of peptides revealed by nonlinear principal component analysis
Authors: Nguyen Phuong H.
Published: October 2006

Employing the recently developed hierarchical nonlinear principal component analysis (NLPCA) method of Saegusa et al. (Neurocomputing 2004;61:57–70 and IEICE Trans Inf Syst 2005;E88‐D:2242–2248), the complexities of the free energy landscapes of several peptides, including triglycine, hexaalanine, and the C‐terminal β‐hairpin of protein G, were studied. First, the performance of this NLPCA method was compared with the standard linear principal component analysis (PCA). In particular, we compared two methods according to (1) the ability of the dimensionality reduction and (2) the efficient representation of peptide conformations in low‐dimensional spaces spanned by the first few principal components. The study revealed that NLPCA reduces the dimensionality of the considered systems much better, than did PCA. For example, in order to get the similar error, which is due to representation of the original data of β‐hairpin in low dimensional space, one needs 4 and 21 principal components of NLPCA and PCA, respectively. Second, by representing the free energy landscapes of the considered systems as a function of the first two principal components obtained from PCA, we obtained the relatively well‐structured free energy landscapes. In contrast, the free energy landscapes of NLPCA are much more complicated, exhibiting many states which are hidden in the PCA maps, especially in the unfolded regions. Furthermore, the study also showed that many states in the PCA maps are mixed up by several peptide conformations, while those of the NLPCA maps are more pure. This finding suggests that the NLPCA should be used to capture the essential features of the systems. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Optimization of the hydrochloric acid concentration used for trifluoroacetate removal from synthetic peptides
Authors: Andrushchenko Valery V. , Vogel Hans J. , Prenner Elmar J.
Published: October 2006

Trifluoroacetate (CF3COO−, or TFA) is almost always present in commercially synthesized peptides. Unfortunately, it has a strong infrared (IR) absorption band at 1673 cm−1, significantly overlapping or even completely obscuring the amide I band of a peptide. In such cases TFA must be removed from the solution in order to be able to use IR absorption spectroscopy for peptide secondary structure determination. The most convenient and widely used procedure involves peptide lyophilization from a 0.1 M HCl solution. In our studies of the tryptophan‐rich antimicrobial peptide indolicidin, we have found that caution should be taken when using this HCl concentration. High HCl concentrations (>10 mM in unbuffered solutions and > 50 mM in buffered solutions) may modify the peptide structure and reduce its thermal stability, thereby interfering with subsequent structural investigations of the peptide. Our results indicate that HCl concentrations between 2 and 10 mM are adequate to remove essentially all TFA impurities without any modification of the peptide secondary structure. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Studies on deprotection of cysteine and selenocysteine side‐chain protecting groups
Authors: Harris Katharine M. , Flemer Stevenson , Hondal Robert J.
Published: October 2006

We present here a simple method for deprotecting p‐methoxybenzyl groups and acetamidomethyl groups from the side‐chains of cysteine and selenocysteine. This method uses the highly elecrophilic, aromatic disulfides 2,2′‐dithiobis(5‐nitropyridine) (DTNP) and 2,2′‐dithiodipyridine (DTP) dissolved in TFA to effect removal of these heretofore difficult‐to‐remove protecting groups. The dissolution of these reagents in TFA, in fact, serves to ‘activate’ them for the deprotection reaction because protonation of the nitrogen atom of the pyridine ring makes the disulfide bond more electrophilic. Thus, these reagents can be added to any standard cleavage cocktail used in peptide synthesis.

The p‐methoxybenzyl group of selenocysteine is easily removed by DTNP. Only sub‐stoichiometric amounts of DTNP are required to cause full removal of the p‐methoxybenzyl group, with as little as 0.2 equivalents necessary to effect 70% removal of the protecting group. In order to remove the p‐methoxybenzyl group from cysteine, 2 equivalents of DTNP and the addition of thioanisole was required to effect removal. Thioanisole was absolutely required for the reaction in the case of the sulfur‐containing amino acids, while it was not required for selenocysteine. The results were consistent with thioanisole acting as a catalyst. The acetamidomethyl group of cysteine could also be removed using DTNP, but required the addition of > 15 equivalents to be effective. DTP was less robust as a deprotection reagent. We also demonstrate that this chemistry can be used in a simultaneous cyclization/deprotection reaction between selenocysteine and cysteine residues protected by p‐methoxybenzyl groups to form a selenylsulfide bond, demonstrating future high utility of the deprotection method. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Process improvement evaluation approach using flow diagrams
Authors: Constant Paul C.
Published: October 2006

Maintaining company processes will afford optimum operation and enhance the company's quality management system. A vital part of maintaining processes is their periodic evaluation. An important part of the monitoring and evaluation process is the flow diagram. A detailed flow diagram is an important tool that affords ease in visualizing the total process and is an aid in locating problem areas. The evaluation of a process is broken down into 15 steps. These steps cover gathering pertinent information, such as problem symptoms from knowledgeable sources and carrying these through their route to potential problem areas to the problems, potential causes, and the root cause of the problem. Knowing the problems brings about the need to assess their impact on the process operation as well as what changes to the process are needed and what impact these changes will have on the product – its improved quality and cost – and other vital information, such as, production rate increase, competition status, and company image. With this information, the appropriate changes are made according to a process change action plan. The plan is executed, and the process is continuously monitored according to a monitoring and evaluation plan. The paper ends with conclusions. Copyright © 2006 John Wiley & Sons, Ltd.
GLP SOPs for equipment calibration and maintenance. Part 2: an organized approach to streamlining procedural documentation
Authors: Rosa Michelle , Colligon Irina
Published: October 2006

As anyone who has had to deal with a Standard Operating Procedure (SOP) system can testify, managing these documents is a Herculean task, requiring full–time commitment. This article proposes an alternative and more efficient approach to building a manageable set of procedural/instructional documents that will help an organization meet its scientific and regulatory needs while alleviating the strain that a gargantuan SOP system can put on its personnel.

Among the benefits of this approach are: (1) Documents are organized to follow the logical and chronological flow of the activities they describe. (2) Documents can be located quickly. (3) Users will find what they need to know, presented in a concise manner, without superfluous information. (4) Increased usability of the documents since there is a logical structure to delivered information; thus, users can control the level of detail based on their need. (5) Reduced effort for upkeep of individual documents. Copyright © 2006 John Wiley & Sons, Ltd.
The role of the study director in GLP
Authors: Garvin Deborah Eyer
Published: October 2006

With the complexity of today's studies, it has become increasingly critical that Study Directors understand all disciplines involved in studies under their responsibility. Every phase of a study directly impacts the outcome. If the Study Director does not have sufficient expertise to evaluate problems and issues in all areas as they occur, then study integrity is compromised. The physical location of the Study Director in a multi‐site study is of less importance than the education, experience and expertise of that individual. The Study Director must be the single point of control and truly qualified to evaluate all the phases of the study, troubleshoot problems, draw appropriate conclusions, tie all aspects together and write the final report. Copyright © 2006 John Wiley & Sons, Ltd.
Comparison Between 2D and 3D‐QSAR Approaches to Correlate Inhibitor Activity for a Series of Indole Amide Hydroxamic Acids
Authors: Katritzky Alan R. , Slavov Svetoslav H. , Dobchev Dimitar A. , Karelson Mati
Published: October 2006

The well‐expressed inhibitor activity of 36 indole amide hydroxamic acids to Histone Deacetylases (HDACs) was analyzed by CODESSA PRO software and the Best Multiple Linear Regression (BLMR) algorithm, to provide a reliable 2D‐QSAR model from a set of more than 800 descriptors. Concurrently, Chem‐X (version 1994) software was used to develop a corresponding 3D‐QSAR model; the steric and electrostatic interactions between a fictitious probe atom “H+” and a set of aligned molecules were evaluated using the CoMFA approach as implemented in Chem‐X. A Partial Least Squares (PLS) procedure generated the principal components needed to build a 3D‐QSAR model. The Weighted Least Squares (WLS) method generated an R2 map of the regions around the molecules important for steric and electrostatic interactions. Enzyme–inhibitor docking calculations were carried out to combine and compare with the results obtained by CoMFA. New potentially active structures were proposed.
Convergence of an s‐Wave calculation of the He ground state
Authors: Mitroy J. , Bromley M. W. J. , Ratnavelu K.
Published: October 2006

The configuration interaction (CI) method using a large Laguerre basis restricted to ℓ = 0 orbitals is applied to the calculation of the He ground state. The maximum number of orbitals included was 60. The numerical evidence suggests that the energy converges as ΔEN ≈ A/N7/2 + B/N8/2 + …, where N is the number of Laguerre basis functions. The electron–electron δ‐function expectation converges as ΔδN ≈ A/N5/2 + B/N6/2 + …, and the variational limit for the ℓ = 0 basis is estimated as 0.1557637174(2) a. It was seen that extrapolation of the energy to the variational limit is dependent on the basis dimension at which the exponent in the Laguerre basis was optimized. In effect, it may be best to choose a nonoptimal exponent if one wishes to extrapolate to the variational limit. An investigation of the natural orbital asymptotics revealed the energy converged as ΔEN ≈ A/N6 + B/N7 + …, while the electron–electron δ‐function expectation converged as ΔδN ≈ A/N4 + B/N5 + …. The asymptotics of expectation values other than the energy showed fluctuations that depended on whether N was even or odd. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Electron affinity of exotic systems under Debye plasma
Authors: Bhattacharyya S. , Sil A. N. , Mukherjee T. K. , Mukherjee P. K. , Vasu P.
Published: October 2006

Electron affinity of plasma embedded muonium (μ+e−) and pionium (π+e−) has been estimated using a general three‐body formalism within variational framework. Electron correlation is taken care of using extended Hylleraas basis sets. The stability of the three‐body systems have been studied under the Debye screening model of the plasma, which changes the Coulombic potential to the screened Coulomb one. The electron affinity of the muonium and pionium is maximum for free systems, and it decreases gradually toward zero with increase of the plasma strength, which tends to push the three‐body system toward gradual instability. The electron correlation contribution to the affinity has been analyzed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Deterministic global optimization for nonlinear model predictive control of hybrid dynamic systems
Authors: Long Christopher E. , Polisetty Pradeep K. , Gatzke Edward P.
Published: October 2006

This paper applies a deterministic non‐convex optimization method for nonlinear model predictive control (NMPC) of systems exhibiting nonlinear hybrid dynamics. The process is represented by a model that incorporates nonlinearity using both continuous state variables and binary variables that define the multiple regimes of operation. The resulting optimization problem is a mixed‐integer nonlinear program (MINLP). A deterministic method is employed to provide rigorous bounds on the solution. In some cases, this method can guarantee global optimality of the non‐convex MINLP. Novel algorithm modifications are presented to improve convergence rates for the deterministic algorithm. The control algorithm is demonstrated using a simulated system of pressure tanks in which the volumetric flow through the process valves switches between distinct flow regimes. Terminal constraints and regime boundary constraints are imposed to promote stability and improve robustness. Formulation limitations and alternatives are discussed to address instances in which the resulting MINLP cannot be solved rapidly enough for real‐time implementation. This work shows that deterministic methods can be applied to NMPC applications while taking stability and uncertainty into account. Copyright © 2006 John Wiley & Sons, Ltd.
The sustainable development area: satisfying basic needs and safeguarding ecological sustainability
Authors: Holden Erling , Linnerud Kristin
Published: October 2006

The aim of this article is to provide a simple and coherent framework for assessing the sustainability of present and future development policies. First, we present the major characteristics of the sustainability concept along three dimensions and suggest how these dimensions can be measured. Second, we construct a diagram, the sustainable development area, and employ data from 118 countries to evaluate the global situation with regard to sustainable development. Third, we outline three different approaches for reaching the sustainable development area and reflect on their possible implications. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Serum biochemistry correlates with the size of tubal ectopic pregnancy on sonography
Authors: Guvendag Guven E. S. , Dilbaz S. , Dilbaz B. , Guven S. , Sahin Ozdemir D. , Haberal A.
Published: October 2006

Objective

To investigate whether there is a correlation between serum biochemistry (human chorionic gonadotropin (hCG), CA 125, progesterone and estradiol) and the common sonographic findings (blob sign, bagel sign or extrauterine gestational sac with cardiac activity) or size of a tubal ectopic pregnancy, and whether there is a difference in serum biochemistry between women with a tubal ectopic pregnancy who are hemodynamically unstable (tachycardia, hypotension, falling hemoglobin levels and/or acute severe abdominal pain) and those who are hemodynamically stable.

Methods

This was a prospective cohort study of 106 women with a tubal ectopic pregnancy. We noted transvaginal ultrasound examination findings including adnexal mass size, and the serum levels of hCG, CA 125, progesterone and estradiol. The data were analyzed retrospectively.

Results

The mean maternal and gestational ages were 30.7 ± 5.7 years and 44 ± 4.2 days, respectively. There was no correlation between serum markers and common sonographic findings. However, in the presence of the bagel sign on ultrasound, hemodynamic stability was more common (P = 0.03). The mean serum hCG concentrations in tubal ectopic pregnancies < 20 mm, 20–40 mm and > 40 mm in size were 2225.3 ± 3166.9, 4124.8 ± 6121.4, and 11 011.8 ± 12 670.1 IU/mL, respectively (P < 0.001). Serum hCG, CA 125 and estradiol values were well correlated with adnexal mass size; for CA 125 this correlation was linear. There was no difference in serum biochemistry between hemodynamically stable and hemodynamically unstable women.

Conclusion

Common sonographic findings of tubal ectopic pregnancy do not correlate with serum biochemistry. High levels of CA 125, hCG or estradiol may suggest a larger adnexal mass in women with uncomplicated tubal pregnancies. Hemodynamically stable and hemodynamically unstable women do not differ in their serum biochemistry. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal screening for congenital heart disease with four‐chamber and outflow‐tract views: a multicenter study
Authors: Oggè G. , Gaglioti P. , Maccanti S. , Faggiano F. , Todros T.
Published: October 2006

Objective

Congenital heart diseases (CHD) are the most common congenital anomalies, and most cases occur in the low‐risk population. Prenatal ultrasound screening based on visualization of the four‐chamber view has had disappointing results in detecting these anomalies thus far. The aim of this study was to evaluate the diagnostic accuracy of ultrasound screening based on the combination of the four‐chamber and outflow‐tract views.

Methods

We conducted a multicenter prospective observational study in 15 obstetric units in the Piedmont Region, Italy. All operators received specific training. Data were recorded regarding visualization of the four‐chamber view and the outflow tracts at each routine scan in pregnancies without any risk factor. When an anomaly was suspected, the patient was sent to the referral center. We obtained the follow‐up data of the newborns until discharge from hospital and calculated the diagnostic accuracy of the test.

Results

9074 ultrasound scans were performed on 7041 women and complete follow‐up information was available for 6368 of them. Fifty‐eight cases of CHD were observed at birth or postmortem (prevalence 9.1‰); 38 of them were diagnosed in utero. The sensitivity of the test was 65.5%, the specificity 99.7%, the positive predictive value 70.4% and the negative predictive value 99.7%. The sensitivity of the four‐chamber view alone was 60.3%.

Conclusions

The sensitivity was significantly higher than that in a similar study performed in 1997 in the same setting. This improvement can be attributed in part to extension of the examination to the outflow‐tract view, but also to technological developments and better training of the operators. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Descriptive models for the system of the natural spread of infection of rice dwarf virus (RDV) by the green rice leafhopper, Nephotettix cincticeps Uhler (Hemiptera: Deltocephalidae)
Authors: Nakasuji Fusao , Kiritani Keizi
Published: October 2006

Seasonal changes in the densities of eggs and of 1st instar nymphs of N. cincticeps, a vector of the rice dwarf virus (RDV) and those in the proportion of virus‐infected rice hills were examined by regular field censuses during the period of 1964–69 at two localities in Kochi, Nangoku and Ino. The proportion of virus‐infected insects in the vector population was measured by the serological test. Mean fecundity of adult females of N. cincticeps in different generations was assessed by the method proposed byHokyo andKiritani (1968) in 1966 and 1967.

Using observed variables as mentioned above, two mathematical models were built up for the system of the natural spread of infection of RDV. Submodels describing generation‐to‐generation changes in densities of eggs, 1st instar nymphs and leafhopper adults were involved in both Models 1 and 2. In Model 1, the proportion (P) of infected insects in the vector population was assumed to be determined directly by the amount (Iv) of infected rice plants in the field. In Model 2, instead of relating P directly to Iv,P was related to the acquisition rate (W) of RDV by the insects and to the effect of RDV (αr) on fecundity and survival of infected insects. Then, W was related to Iv.

The estimates of P by these models fitted well to the observed values for 1st to 3rd generations but a great deviation was noted in 4th and 5th generations. For the percentage of infected rice hills, both models gave relatively good estimates in the early planted rice, though they gave overestimated values in the late planted rice.
Application of the method to the analysis of spatial patterns by changing the quadrat sizemethod to the analysis of spatial patterns by changing the quadrat size
Authors: Iwao Syun'iti
Published: October 2006

A method for the analysis of spatial pattern using quadrats of different sizes is developed on the basis of the relationship of mean crowding () to mean density (m). The ‐on‐m regression obtained by successive changes in quadrat size in a single population (unit‐size relation) shows a characteristic pattern according to the type of distribution. By aid of the ρ‐index proposed here, we can distinguish the random, aggregated and uniform distributions of the basic components (individual or group of individuals). The ρ serves as an index of spatial correlation between neighbouring quadrats, and it also provides information on the approximate area occupied by clump (colony), distribution pattern of individuals within clumps, and possibly the distribution pattern of clumps themselves.

Even in a specified type of distribution, the unit‐size relation is not necessarily identical with the relation for a series of populations at a particular quadrat size (series relation). The changes in the series relationship with successive changes of quadrat sizes are also considered for some basic patterns of distributions. The combined use of the unit‐size and the series relations for a set of populations of the species under study may provide a satisfactory picture of the spatial pattern characteristic of the species.

Application of the method is illustrated by using distribution data of several species of animals and plants. The advantage of the present method over other methods are discussed, and the formulae for determining the optimum quadrat unit in sampling surveys are given.
The spatial pattern in a natural population of goldenrod (Solidago altissima L.), with particular reference to its change during the shoot growth
Authors: Kitamoto Toshio
Published: October 2006

In a natural population of Solidago altissima L., the changes in the spatial pattern of shoots in the course of growth were studied. The results obtained were summarized as follows:

The spatial pattern changed from clumped to random distribution as plants grew. The change seemed to be resulted from some density‐dependent process acting at a small spatial scale, probably the competition for space.

Large plants tended to distribute themselves more uniformly over the space than the small ones but at the mature stage of growth such a difference was not obviously recognized. The process of appearance of the small‐sized plants during successive periods also seemed to be dependent on local density.

Large plants at the early stage of growth tended to survive better, and there was a positive correlation between initial size and the size at maturity.

From these results, it is inferred that the change of spatial pattern from clumped to random distribution is largely due to the elimination of small shoots as the result of competition for space among individual shoots.