bluuebunny/crossref_metadata_2025 huggingface dataset:
29Si–13C spin–spin couplings over Si–O–Carom link
Authors: Sýkora Jan , Blechta Vratislav , Sychrovský Vladimír , Hetflejš Jiří , Šabata Stanislav , Soukupová Ludmila , Schraml Jan
Published: April 2006

29Si–13C couplings were measured in para substituted silylated phenols, XC6H4OSiR1R2R3(X 2, CF3, Cl, F, H, CH3, CH3O). The SiR1R2R3 silyl groups included trimethylsilyl (Si(CH3)3, TMS), tert‐butyldimethylsilyl (Si(CH3)2C(CH3)3, TBDMS), dimethylsilyl (SiH(CH3)2, DMS), and tert‐ butyldiphenylsilyl (Si(C6H5)2C(CH3)3, TBDPS). Previously developed (Si,C,Si)gHMQC methods and narrow 29Si lines allowed the determination of coupling constants over up to five bonds. Besides the number of intervening bonds between the silicon and carbon atoms, all the measurable couplings depend also on the nature of the substituents on the silicon. The two‐ and three‐bond couplings are not affected by ring substitution in the para position. These properties render the 29Si–13C couplings suitable for line assignment in the spectra of silylated polyphenols. The experimental results are in reasonable agreement with theoretical calculations. The calculations show, in agreement with the data reported in the literature for couplings between other nuclei, that the two‐bond and three‐bond couplings, which are of similar magnitudes, are of opposite signs. If the signs of these geminal and vicinal couplings could be determined experimentally, they would greatly facilitate the line assignment. The four‐ and five‐bond couplings are affected by the substituent X in a nontrivial manner. Copyright © 2006 John Wiley & Sons, Ltd.
Inversion recovery radial MRI with interleaved projection sets
Authors: Peters Dana C. , Botnar René M. , Kissinger Kraig V. , Yeon Susan B. , Appelbaum Evan A. , Manning Warren J.
Published: April 2006

The radial trajectory has found applications in cardiac imaging because of its resilience to undersampling and motion artifacts. Recent work has shown that interleaved and weighted radial imaging can produce images with multiple contrasts from a single data set. This feature was investigated for inversion recovery imaging of scar using a radial technique. The 2D radial imaging method was modified to acquire quadruply interleaved projection sets within each acquisition window of the cardiac cycle. These data were reconstructed using k‐space weightings that used a smaller segment of the acquisition window for the central k‐space data, the determinant of image contrast. This method generates four images with different T1 weightings. The novel approach was compared with noninterleaved radial imaging, interleaved radial without weightings, and Cartesian imaging in simulations, phantoms, and seven subjects with clinical myocardial infarction. The results show that during a typical acquisition window after an inversion pulse, magnetization changes rapidly. The interleaved acquisition provided better image quality than the noninterleaved radial acquisition. Interleaving with weighting provided better quality when the inversion time (TI) was shorter than optimal; otherwise, interleaving without weighting was superior. These methods enable a radial trajectory to be employed in conjunction with preparation pulses for viability imaging. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Methionine‐dependence phenotype of tumors: Metabolite profiling in a melanoma model usingL‐[methyl‐13C]methionine and high‐resolution magic angle spinning1H–13C nuclear magnetic resonance spectroscopy
Authors: Morvan Daniel , Demidem Aicha , Guenin Samuel , Madelmont Jean Claude
Published: April 2006

Tumors frequently have abnormalL‐methionine (Met) metabolism, the so‐called Met‐dependence phenotype that refers to the inability to proliferate in the absence of Met. However, the origin of this phenotype is still unknown and may arise from one of several pathways of Met metabolism. To help characterize the metabolic features of Met‐dependent/independent phenotypes, the fate of the methyl carbon ofL‐[methyl‐13C]Met was chased in a murine model of malignant melanoma (B16‐F1) in vitro and in vivo. Growth curves under Met restriction showed that melanoma cells in vitro were Met‐independent, whereas implanted melanoma tumors in vivo were Met‐dependent. Label‐assisted high‐resolution magic angle spinning1H‐13C NMR spectroscopy metabolite profiling showed that, in vitro, creatine and phosphatidylcholine13C‐enrichments were poor, butS‐adenosyl‐Met and posttranslationally N‐methylated protein signals were strong. In contrast, in vivo, creatine and phosphatidylcholine enrichments were strong butS‐adenosyl‐Met and N‐methylated protein signals were poor. In addition, in vivo, transsulfuration was very efficient, consumed one‐carbon units originating from the methyl carbon of Met, and yielded taurine labeling. From these data, the Met‐dependent/independent phenotypes appear closely related to the source of one‐carbon units. Thus,L‐[methyl‐13C]Met‐assisted NMR spectroscopy metabolite profiling allowed the discrimination between Met‐dependence and Met‐independence and provided novel mechanistic information on their origin. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Bolus delay and dispersion in perfusion MRI: Implications for tissue predictor models in stroke
Authors: Calamante Fernando , Willats Lisa , Gadian David G. , Connelly Alan
Published: April 2006

Perfusion maps, which are calculated from dynamic‐susceptibility contrast (DSC)‐MRI data by deconvolution of the arterial input function (AIF), are commonly used to predict tissue infarction in acute stroke. However, since the AIF is commonly measured in a major artery, there can be perfusion measurement errors associated with bolus delay/dispersion. Although methods to account for delay‐related errors have been proposed, the effect of dispersion is more difficult to deal with and is usually left uncorrected. This study presents an assessment of the delay–dispersion relationship in a group of patients. Although a significant correlation was observed with one of the bolus delay definitions used, the estimation of the dispersion from the degree of delay was unreliable. Importantly, the dispersion observed in many patients was sufficient to result in substantial perfusion errors. The results are compared with previous numerical simulations, and their implications for the assessment and management of acute stroke are discussed. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
MRI analysis of angiogenesis during mouse embryo implantation
Authors: Plaks Vicki , Kalchenko Vyacheslav , Dekel Nava , Neeman Michal
Published: April 2006

Uterine receptivity and embryo implantation depend on local induction of angiogenesis and vascular permeability. Poor uterine receptivity has been implicated in implantation failure; however, relatively little is known about the mechanism that underlies endometrial vascular hyperpermeability in implantation sites. Here we show that contrast‐enhanced (CE)‐MRI and fluorescence microscopy using biotin‐BSA‐GdDTPA allowed high‐resolution detection and quantitative assessment of mouse embryo implantation sites as early as embryonic day 4.5 (E4.5), and subsequent vascular expansion at E5.5. Vessel permeability, but not blood volume, was significantly elevated in E4.5 implantation sites relative to nonimplanted uterus, showing that elevation of vascular permeability is a very early response preceding E4.5. A significantly increased blood volume was detected by MRI and fluorescence microscopy in implantation sites between E4.5 and E5.5. On the other hand, despite the increase in blood volume, implantation sites showed only a small nonsignificant further increase in vascular permeability during these 2 days, demonstrating the rapid dynamics of vascular remodeling during the early days of pregnancy. Functional imaging by MRI, as reported here, allows multiparametric measurement of angiogenesis during normal mouse implantation and would facilitate the application of MRI to evaluate involvement of the vasculature in mouse models of impaired implantation. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
MR susceptometry for measuring global brain oxygen extraction
Authors: Fernández‐Seara María A. , Techawiboonwong Aranee , Detre John A. , Wehrli Felix W.
Published: April 2006

Monitoring of oxygen saturation in jugular venous blood gives an estimate of the balance of global oxygen delivery and cerebral oxygen consumption. We present a noninvasive approach to measure oxygen saturation in vivo in the internal jugular vein using MR susceptometry by exploiting the characteristic susceptibility of deoxyhemoglobin, and demonstrate the feasibility of performing such measurements in a group of subjects. We assessed the sensitivity of the method for detecting small changes in oxygen saturation by monitoring the variations observed during breath‐holding and hypoventilation experiments. Unlike alternative methods, the susceptometric technique does not require calibration. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Utrophin is a calpain substrate in muscle cells
Authors: Courdier‐Fruh Isabelle , Briguet Alexandre
Published: April 2006

Calpains are Ca2+‐dependent cytosolic cysteine proteases that participate in the pathology of Duchenne muscular dystrophy (DMD). Utrophin is a functional homolog of dystrophin that partially compensates for dystrophin deficiency in myofibers of mdx mice. In this study, we investigated the susceptibility of utrophin to cleavage by calpain in vitro and in muscle cells. We found that utrophin is a direct in vitro substrate of purified calpain I and II. Cleavage of utrophin by calpain I or II generates specific degradation products that are also found in cultured control and DMD myotubes under conditions with elevated intracellular Ca2+ levels. In addition, we showed that activation of cellular calpains by Ca2+ ionophore treatment reduces utrophin protein levels in muscle cells and that calpain inhibition prevents this Ca2+‐induced reduction in utrophin levels. These observations suggest that, beside its known effect on general muscle protein degradation, calpain contributes to DMD pathology by specifically degrading the compensatory protein utrophin. Muscle Nerve, 2006
SNMP GetRows: an effective scheme for retrieving management information from MIB tables
Authors: Chen Yen‐Cheng , Chan Io‐Kuan
Published: April 2006

Management information accessible via SNMP is organized in the Management Information Base (MIB). Many management applications are based on management information within an MIB table. The management information useful for management applications may be located in some rows of an MIB table. Owing to the limitation of current SNMP GetNext and GetBulk services, it is usually inevitable to retrieve all the rows of an MIB table even if some of them are needed. As the size of the MIB table grows, the object retrieval will incur considerable bandwidth and latency. Without loss of the simplicity of SNMP, we propose a novel SNMP service, called GetRows, to provide the capability of object selection via SNMP. Using GetRows, a management application can specify criteria for evaluating rows of an MIB table. Only the object instances in the rows selected by the criteria will be retrieved. Thus, less bandwidth and latency can be achieved by using the proposed GetRows service. Copyright © 2006 John Wiley & Sons, Ltd.
Improved outcome in childhood acute myeloid leukemia in Singapore with the MRC AML 10 protocol
Authors: Tan Ronald M. , Quah Thuan Chong , Aung LeLe , Liang Shen , Kirk Richard C. , Yeoh Allen E.J.
Published: April 2006

Background

The introduction of the United Kingdom Medical Research Council's 10th AML trial (MRC AML 10) protocol incorporating high‐dose anthracycline therapy has improved outcome of children with acute myeloid leukemia (AML). In this study, we review the results of childhood AML therapy in a Singapore university hospital over the last 17 years emphasizing toxicity and outcome.

Procedure

Retrospective analysis revealed 34 children with AML between 1988 and 2003. Prior to September 1996, therapy consisted of: POG‐8498 (n = 10), others (n = 9). From September 1996, all but one of 15 children received MRC AML 10 treatment.

Results

At the time of analysis, 17 had died from disease, and 17 patients were alive among whom 2 had relapsed. MRC AML 10‐treated patients (n = 14) had significantly better 3‐year overall, event‐free, and disease‐free survival (74% vs. 35%, 77% vs. 20%, 83% vs. 31%; P = 0.019, P = 0.002, and P = 0.010, respectively) and were likelier to achieve complete remission (CR) than non‐MRC AML 10 patients (P = 0.102). Among patients who achieved CR, MRC AML 10‐treated patients were significantly more likely to achieve CR after only one cycle of chemotherapy (P = 0.016). Hematologic toxicity was similar among the different regimens (P = 0.9).

Conclusions

These findings suggest that MRC AML 10 treatment results in significantly superior survival, without excess toxicity. Future studies should attempt to elucidate the relative importance of individual MRC AML 10 components and reduce the high cumulative anthracycline dose without compromising outcome. Pediatr Blood Cancer 2007;48:262–267. © 2006 Wiley‐Liss, Inc.
Overview of the preparation of pure polyaniline and conductive composites in dispersed media and by thermal processes: from laboratory to semi‐industrial scale
Authors: Kohut‐Svelko Nicolas , Dinant Frédéric , Magana Sylvain , Clisson Gérald , François Jeanne , Dagron‐Lartigau Christine , Reynaud Stéphanie
Published: April 2006

Intrinsically conductive polymers (ICPs) and conductive composites offer many potential industrial applications due to their conductive properties, processability and mechanical properties. Much work has been carried out to develop the synthesis and formulation of various conductive polymers. Nevertheless, polyaniline (PANI) seems to be one of the most interesting conductive polymer based on the low cost of its synthesis, its conductive properties and its thermal and environmental stability. In this paper, we describe the synthesis and formulation of conductive composites containing PANI by considering two synthetic approaches. The first one is based on the oxidative polymerization of aniline. This synthesis has been optimized from laboratory‐scale to a 50 L pilot‐plant reactor. After a post‐doping procedure, the composite is obtained using a twin‐screw extruder. The second approach concerns a core/shell synthesis (polymer matrix/PANI) procedure which allows synthesis and formulation at the same time. Conductive composites of various compositions (polymer matrix/PANI content and additives) were synthesized by both of these methods and the advantages and drawbacks of each of them are discussed. Copyright © 2006 Society of Chemical Industry
Reactivity control in anionic polymerization of ethylenic and heterocyclic monomers through formation of ‘ate’ complexes
Authors: Carlotti Stéphane , Desbois Philippe , Billouard Cyrille , Deffieux Alain
Published: April 2006

The reactivity and selectivity of active species are the key parameters in the design of living/controlled polymerizations. We have shown that alkyl metal derivatives, such as dialkylmagnesium or trialkylaluminum derivatives, when used as additives to conventional anionic polymerization systems, are very effective mediators for the polymerization control of both ethylenic and heterocyclic monomers. When added to alkali metal alkyl initiators, typically alkyl lithium, for styrene and dienes anionic polymerization they strongly retard the reactivity of the polystyryl and polybutadienyl propagating species and allow control of the polymerization of styrene under very unusual conditions (bulk, very high temperatures). On the contrary, when used in combination with quite similar alkali‐metal‐based initiators in the anionic polymerization of ethylene oxide or propylene oxide, these additives drastically enhance the reactivity and the selectivity of the involved propagating species, thus allowing a fast ‘living‐like’ polymerization to proceed at low temperatures in hydrocarbon media. Copyright © 2006 Society of Chemical Industry
A novel approach to the preparation of thermoplastic polyurethane elastomer and polyamide 6 blends by in situ anionic ring‐opening polymerization of ε‐caprolactam
Authors: Hou Lian‐Long , Liu Hong‐Zhi , Yang Gui‐Sheng
Published: April 2006

Blends of thermoplastic polyether‐based urethane elastomer (TPEU) and monomer casting polyamide 6 (MCPA6) were prepared using ε‐caprolactam as reactive solvent, with caprolactam sodium as a catalyst in the presence of TPEU, with TPEU content varying from 2.5% to 10% by weight. In situ anionic ring‐opening polymerization and in situ compatibilization to prepare TPEU/MCPA6 blends were carried out in one step. The TPEU chains, which underwent thermal dissociation in amine solvents to bear isocyanate groups, acted as macroactivator to initiate MCPA6 chain growth from the TPEU chains and form graft copolymers of TPEU‐co‐MCPA6 to improve compatibility between TPEU and MCPA6. The structure and thermal properties were characterized by means of Fourier transform infrared spectroscopy, 1H‐NMR spectroscopy, differential scanning calorimetry and scanning electron microscopy. Copyright © 2006 Society of Chemical Industry
Stereocomplexed polylactides (Neo‐PLA) as high‐performance bio‐based polymers: their formation, properties, and application
Authors: Fukushima Kazuki , Kimura Yoshiharu
Published: April 2006

Polymeric materials prepared from renewable natural resources are now being accepted as “bio‐based polymers”, because they are superior to the conventional petroleum‐based polymers in reducing the emission of carbon dioxide. Among them, poly(L‐lactide) (PLLA) prepared by fermentation and polymerization is paid an immediate attention. Although PLLA exhibits a broad range of physico‐chemical properties, its thermal and mechanical properties are somewhat poorer for use as ordinary structural materials. For improving these inferior properties, a stereocomplex form consisting of PLLA and its enantiomer poly(D‐lactide) (PDLA) has high potential because of showing high melting nature (230 °C). It can be formed by simple polymer blend of PLLA and PDLA or more easily with stereoblock polylactides (sb‐PLA) which are PLLA/PDLA block copolymers. These novel PLA polymers, named “Neo‐PLA”, can provide a wide range of properties that have never be attained with single PLLA. Neo‐PLA retains sustainability or bio‐based nature, because both monomers L‐ and D‐lactic acids are manufactured from starch by fermentation. Copyright © 2006 Society of Chemical Industry
Solid‐state linear viscoelastic properties of intercalated poly(L‐lactide)/organo‐modified montmorillonite hybrids
Authors: Nam Pham Hoai , Kaneko Masahiro , Ninomiya Naoya , Fujimori Atsuhiro , Masuko Toru
Published: April 2006

Hybrids of poly(L‐lactide)/organophilic clay (PLACHs) have been prepared by a melt‐compounding process using poly(L‐lactide) (PLLA) and different contents of surface‐treated montmorillonite modified with a dimethyl dioctadecyl ammonium salt. The dispersion structures of clay particles in PLACHs were investigated using wide‐angle X‐ray diffraction and transmission electron microscopy. The solid‐state linear viscoelastic properties for these PLACHs were examined as functions of temperature and frequency. The incorporation of organo‐modified silicate into PLLA matrix enhanced significantly both storage moduli (E′) and loss moduli (E″). The strong enhancement observed in dynamic moduli of PLACHs could be attributed to uniformly dispersed state of the clay particles with high aspect ratio (= length/thickness of clay) and the intercalation of the PLLA chains between silicate layers. Copyright © 2006 Society of Chemical Industry
Melt rheological properties of polypropylene–polyamide6 blends compatibilized with maleic anhydride‐grafted polypropylene
Authors: Shi Dean , Jiang Fengdan , Ke Zhou , Yin Jinghua , Li Robert Kwok‐Yiu
Published: April 2006

The melt rheological properties of binary uncompatibilized polypropylene–polyamide6 (PP–PA6) blends and ternary blends compatibilized with maleic anhydride‐grafted PP (PP–PP‐g‐MAH–PA6) were studied using a capillary rheometer. The experimental shear viscosities of blends were compared with those calculated from Utracki's relation. The deviation value δ between these two series of data was obtained. In binary PP–PA6 blends, when the compatibility between PP and PA6 was poor, the deformation recovery of dispersed PA6 particles played the dominant role during the capillary flow, the experimental values were smaller than those calculated, and δ was negative. The higher the dispersed phase content, the more deformed the droplets were and the lower the apparent shear viscosity. Also, the absolute value of δ increased with the dispersed phase composition. In ternary PP–PP‐g‐MAH–PA6 systems, when the compatibility between PP and PA6 was enhanced by PP‐g‐MAH, the elongation and break‐up of the dispersed particles played the dominant role, and the experimental values were higher than calculated. It was observed that the higher the dispersion of the PA6 phase, the higher the δ values of the ternary blends and the larger the positive deviation. Unlike uncompatibilized blends, under high shear stress with higher dispersed phase content, the PP‐g‐PA6 copolymer in compatibilized blends was pulled out from the interface and formed independent micelles in the matrix, which resulted in reduced total apparent shear viscosity. The δ value decreased with increasing shear stress. Copyright © 2006 Society of Chemical Industry
Plasma Hydrophilization Effect on Different Textile Structures
Authors: Hossain Mokbul M. , Herrmann Axel S. , Hegemann Dirk
Published: April 2006

Summary: The degree of plasma‐induced hydrophilization and the stability of the treatment are closely linked to the textile structure and the weave construction. This study investigates the plasma activation of polyester (PES) fabric structures to improve their wettability, as well as the aging effects. The hydrophilic modification is carried out by low pressure plasma treatments using oxygen containing gaseous mixtures (Ar/O2 and He/O2), and it is characterized by calculating contact angles (static and advancing) from capillary rise tests with water. In all cases, the wettability of plasma‐treated PES fabrics is improved significantly due to the formation of polar groups on the surface. In particular, the hydrophilicity of looser structured fabrics is improved remarkably as compared to tightly woven fabrics. Furthermore, the capillary phenomenon in fibrous assemblies is also described in this study.

SEM image of a tightly woven fabric and the schematic representation of the liquid flow within a plasma‐hydrophilized fabric by capillary forces.

magnified image

SEM image of a tightly woven fabric and the schematic representation of the liquid flow within a plasma‐hydrophilized fabric by capillary forces.
Non‐Thermal Plasma and TiO2‐Assisted n‐Heptane Decomposition
Authors: Pekárek Stanislav , Pospíšil Milan , Krýsa Josef
Published: April 2006

Summary: We studied the decomposition of n‐heptane by DC hollow‐needle‐to‐mesh electrical discharge with or without a TiO2 photocatalyst. The discharge was enhanced by flowing air or a mixture of air with n‐heptane through the needle. The experiments with photocatalyst were performed with a TiO2‐coated stainless steel mesh and with a mesh covered with TiO2 globules. In each of these cases, the efficiency of n‐heptane decomposition increases with increasing energy density. A maximum decomposition efficiency of 50.4% was obtained for the discharge with a mesh covered with TiO2 globules for an energy density of 350 kJ · m−3 at a relative humidity of the mixture of 27%. For a given energy density, the decomposition efficiency is largest for the mesh covered with TiO2 globules. In this case, the humidity improves the decomposition efficiency.

Effect of humidity on the efficiency of n‐heptane decomposition for the DC discharge using a mesh covered with TiO2 globules.

magnified image

Effect of humidity on the efficiency of n‐heptane decomposition for the DC discharge using a mesh covered with TiO2 globules.
Acaricidal activities of paeonol and benzoic acid from Paeonia suffruticosa root bark and monoterpenoids against Tyrophagus putrescentiae (Acari: Acaridae)
Authors: Tak Jun‐Hyung , Kim Hyun‐Kyung , Lee Seung‐Hwan , Ahn Young‐Joon
Published: April 2006

The acaricidal activities of paeonol (2′‐hydroxy‐4′‐methoxyacetophenone) and benzoic acid identified in the root bark of tree peony, Paeonia suffruticosa Andrews, against copra mite, Tyrophagus putrescentiae (Schrank), adults were examined using direct contact and vapour phase toxicity bioassays and compared with those of cinnamyl acetate, cinnamyl alcohol and 37 monoterpenoids as well as the acaricides benzyl benzoate, dibutyl phthalate and N,N‐diethyl‐m‐toluamide (DEET). Based on LD50 values in fabric piece contact toxicity bioassays, the acaricidal activities of benzoic acid (4.80 µg cm−2) and paeonol (5.29 µg cm−2) were comparable to that of benzyl benzoate (4.46 µg cm−2) but more pronounced than those of DEET (30.03 µg cm−2) and dibutyl phthalate (25.23 µg cm−2). In vapour phase toxicity bioassays, paeonol and benzoic acid were much more effective in closed containers than in open ones, indicating that the effects of these compounds were largely due to action in the vapour phase. As judged by 24 h LD50 values, (1S)‐(−)‐verbenone (7.42 mg per disc) was the most toxic fumigant, followed by (1S)‐(−)‐camphor, (S)‐(+)‐carvone, (R)‐(−)‐linalool and (±)‐camphor (10.45–18.18 mg). Potent fumigant toxicity was also observed with paeonol, (2S,5R)‐(−)‐menthone, (±)‐citronellal, benzoic acid, (1S,4R)‐(−)‐α‐thujone and (R)‐(+)‐pulegone (25.10–34.63 mg). Neither benzyl benzoate, DEET nor dibutyl phthalate caused fumigant toxicity. Paeonia root bark‐derived materials, particularly paeonol and benzoic acid, as well as the monoterpenoids described, merit further study as potential acaricides or as leads for the control of T. putrescentiae. Copyright © 2006 Society of Chemical Industry
Cathodoluminescence of SiOx under‐stoichiometric silica layers
Authors: Salh Roushdey , von Czarnowski A. , Zamoryanskaya M. V. , Kolesnikova E. V. , Fitting H.‐J.
Published: April 2006

Under‐stoichiometric thin silica layers SiOx with different stoichiometric degree 1 ≤ x ≤ 2, were prepared by thermal evaporation of silicon monoxide in vacuum and in ambient oxygen atmosphere of various pressure onto crystalline silicon substrates. The chemical composition has been determined by Fourier transform infrared spectroscopy (FTIR). A special formula is derived to correlate the stoichiometric degree x with the wavenumber of the main TO stretching mode (Si–O–Si) in silica, finally to determine the actual composition values x of the layers. Cathodoluminescence (CL) of these layers shows the development of typical amorphous SiO2 luminescence bands at the composition threshold x > 1.5 and then onwards to x = 2. These luminescence bands were observed at 4.3, 2.7, 2.15, and 1.9 eV. The green–yellow luminescence (2.15 eV) is strongly increasing with the annealing temperature up to 1300 °C and is assigned to phase separation of SiOx into Si and SiO2 and formation of hexamer silicon rings in the understoichiometric silica network. Finally we observe Si nanoclusters by means of transmission elec‐ tron microscopy (TEM) micrographs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
EPR study of the structural phase transitions in Fe3+ doped TlInS2
Authors: Mikailov F. A. , Kazan S. , Rameev B. Z. , Acikgoz M. , Aktaş B.
Published: April 2006

The results of low temperature EPR investigations of Fe doped TlInS2 single crystals in the temperature range 5–300 K are presented. The EPR signal due to Fe3+ centers located at the centers of InS4 tetrahedrons has been observed. It has been established that the resonance lines exhibit a slight shift and remarkable splitting at the temperatures lower than 200 K, which is attributed to the effect of the ferroelectric phase transition. The rotational patterns of the resonance fields reveal a doubling of the number of centers at low temperatures. The preliminary simulation indicates that the doubling is related to the rotation of the principal axis system of the centers, while the magnitude of fine structure splitting is nearly the same. ( © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Six Sigma Literature: A Review and Agenda for Future Research
Authors: Brady James E. , Allen Theodore T.
Published: April 2006

Like quality management in general, Six Sigma has penetrated into most sectors of today's business world. Although Six Sigma originated in industry, it has inspired a considerable amount of academic literature. This paper reviews this literature describing the trends, sources, and findings. The paper also seeks to synthesize the literature, with an emphasis on establishing its relationship to quality management theory and topics for future research. In doing so, there is an attempt to answer the following fundamental questions. (i) What is Six Sigma? (ii) What are its impacts on operational performance? (iii) What roles can academics usefully play in relation to Six Sigma? Copyright © 2006 John Wiley & Sons, Ltd.
Fraction of Design Space Plots for Split‐plot Designs
Authors: Liang Li , Anderson‐Cook Christine M. , Robinson Timothy J.
Published: April 2006

In industrial experiments, restrictions on the execution of the experimental runs or the existence of one or more hard‐to‐change factors often leads to split‐plot experiments, where there are two types of experimental units and two independent randomizations. The resulting compound symmetric error structure, as well as the settings of whole‐plot and subplot factors, play important roles in the performance of split‐plot experiments. When the practitioner is interested in predicting the response, a response surface design for a second‐order model such as a central composite design (CCD) is often used. The prediction variance of second‐order designs under a split‐plot error structure is often of interest. In this paper, fraction of design space (FDS) plots are adapted to split‐plot designs. In addition to the global curve exploring the entire design space, sliced curves at various whole‐plot levels are presented to study prediction performance for subregions in the design space. The different sizes of the constrained subregions are accounted for by the proportional size of the sliced curves. The construction and use of the FDS plots are demonstrated through two examples of the restricted CCD in split‐plot schemes. We also consider the impact of the variance ratio on design performance. Copyright © 2006 John Wiley & Sons, Ltd.
Classes of Split‐plot Response Surface Designs for Equivalent Estimation
Authors: Parker Peter A. , Kowalski Scott M. , Vining G. Geoffrey
Published: April 2006

When planning an experimental investigation, we are frequently faced with factors that are difficult or time consuming to manipulate, thereby making complete randomization impractical. A split‐plot structure differentiates between the experimental units associated with these hard‐to‐change factors and those that are relatively easy‐to‐change. Furthermore, it provides an efficient strategy that integrates the restrictions imposed by the experimental apparatus into the design structure. In this paper, several industrial and scientific examples are presented to highlight design considerations when a restriction on randomization is encountered. We propose classes of split‐plot response designs that provide an intuitive and natural extension from the completely randomized context. For these designs, the ordinary least‐squares estimates of the model are equivalent to the generalized least‐squares estimates. This property provides best linear unbiased estimators and simplifies model estimation. The design conditions that provide equivalent estimation are presented and lead to design construction strategies to transform completely randomized Box–Behnken, equiradial and small composite designs into a split‐plot structure. Published in 2006 by John Wiley & Sons, Ltd.
New approach using the relativistic Hamilton–Jacobi equation to evaluate the correct energy levels for the hydrogen atom
Authors: Nascimento D. L. , Fonseca A. L. A.
Published: April 2006

The aim of the present study is to propose a model based on classical field theory to study atomic and molecular systems. Starting from the basic principles of the special relativity theory (SRT), the model is described by taking the interaction between two moving particles with the standing wave radiated from the particles in the four‐dimensional space–time. According to the classical theory of fields, the geometrical properties of the solutions are governed by a classical‐like equation of motion. An eigenvalue equation is derived from an improvement of the relativistic variational method introduced by Schrödinger in 1926 1. This formalism is applied to the standard hydrogen atom problem, yielding solutions of the equation of motion by integrals of action and by solving the associated differential eigenvalue equation. Both sets of solutions reproduce the correct fine structure of the energy levels. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
First hyperpolarizabilities of vinylogue organometallic sesquifulvalene chromophores: A DFT study
Authors: Mang Chaoyong , Wu Kechen
Published: April 2006

Static first hyperpolarizabilities of vinylogue mono‐ and bimetallic sesquifulvalene chromophores, [(η5‐C5H5)M{μ−(η5‐C5H4)CHCH(η6‐C7H7)}]+ (M = Fe, Ru, and Os) and [(η5−C5H5)M{μ−(η5‐C5H4)CHCH(η6‐C7H7)}Cr(CO)3]+ (M = Fe, Ru, and Os) have been calculated within DFT theoretical approach. The results agree well with the recent Hyper‐Rayleigh scattering (HRS) measurements. The coordinated transition metals reduced the magnitude of dipole moment and first hyperpolarizability. The metal‐to‐ligand charge‐transfer contributes to the first hyperpolarizability and, as a result, the rational substitution of coordinated metal could modulate the first hyperpolarizability of the organometallic chromophores. The study would be helpful to understand optical nonlinearities in organometallic complexes. © 2006 Wlley Periodicals, Inc. Int J Quantum Chem, 2006
An analysis of complex multiple‐choice science–technology–society items: Methodological development and preliminary results
Authors: Vázquez‐Alonso Ángel , Manassero‐Mas María‐Antonia , Acevedo‐Díaz José‐Antonio
Published: April 2006

The scarce attention to the assessment and evaluation in science education research has been especially harmful for teaching science–technology–society (STS) issues, due to the dialectical, tentative, value‐laden, and polemic nature of most STS topics. This paper tackles the methodological difficulties of the instruments that monitor views related to STS topics and rationalizes a quantitative methodology and an analysis technique to improve the utility of an empirically developed multiple‐choice item pool, the Questionnaire of Opinions on STS. This methodology embraces an item‐scaling psychometrics based on the judgments by a panel of experts, a multiple response model, a scoring system, and the data analysis. The methodology finally produces normalized attitudinal indices that represent the respondent's reasoned beliefs toward STS statements, the respondent's position on an item that comprises several statements, or the respondent's position on an entire STS topic that encompasses a set of items. Some preliminary results show the methodology's ability to evaluate the STS attitudes in a qualitative and quantitative way and for statistical hypothesis testing. Lastly, some applications for teacher training and STS curriculum development in science classrooms are discussed. © 2006 Wiley Periodicals, Inc. Sci Ed 90:681–706, 2006
A natural history model of stage progression applied to breast cancer
Authors: Plevritis Sylvia K. , Salzman Peter , Sigal Bronislava M. , Glynn Peter W.
Published: April 2006

Invasive breast cancer is commonly staged as local, regional or distant disease. We present a stochastic model of the natural history of invasive breast cancer that quantifies (1) the relative rate that the disease transitions from the local, regional to distant stages, (2) the tumour volume at the stage transitions and (3) the impact of symptom‐prompted detection on the tumour size and stage of invasive breast cancer in a population not screened by mammography. By symptom‐prompted detection, we refer to tumour detection that results when symptoms appear that prompt the patient to seek clinical care. The model assumes exponential tumour growth and volume‐dependent hazard functions for the times to symptomatic detection and stage transitions. Maximum likelihood parameter estimates are obtained based on SEER data on the tumour size and stage of invasive breast cancer from patients who were symptomatically detected in the absence of screening mammography. Our results indicate that the rate of symptom‐prompted detection is similar to the rate of transition from the local to regional stage and an order of magnitude larger than the rate of transition from the regional to distant stage. We demonstrate that, in the even absence of screening mammography, symptom‐prompted detection has a large effect on reducing the occurrence of distant staged disease at initial diagnosis. Copyright © 2006 John Wiley & Sons, Ltd.
A unimodal curve for primate group size along a gradient of population density
Authors: Horiuchi Shiro
Published: April 2006

When plotted along a gradient of population density, the mean group size in populations of several primate species has a unimodal distribution, i.e., mean group size is greater at intermediate population densities than at higher or lower population densities. In this study I present a mathematical model to clarify the cause of this relationship. Population density is assumed to affect group size by enhancing between‐ or within‐group competition and by changing the number of neighboring groups around each group. The mean group size is predicted to decline as population density increases above a critical value, owing to the increasing number of neighboring groups.
Vitamin B12 and vitamin B6 supplementation is needed among adults with phenylketonuria (PKU)
Authors: Hvas A. M. , Nexo E. , Nielsen J. B.
Published: April 2006

Phenylketonuria (PKU) is caused by an autosomal recessive deficiency of the enzyme phelnylalanine hydroxylase leading to a failure to convert phenylalanine to tyrosine. To avoid irreversible neurological damage because of increased phenylalanine, treatment is instituted rapidly after birth. We examined 31 adult PKU patients living on a less protein‐restricted diet. Theoretically, these PKU patients had an increased risk of developing vitamin B12 and B6 deficiency because of a limited intake of animal products. Besides laboratory tests (n = 31) we obtained clinical information (n = 30) and detailed information on food consumption (n = 28). Three‐quarters of the patients had early biochemical signs of vitamin B12 deficiency. In spite of a normal folate status, 9 (29%) had a plasma homocysteine above 12 μmol/L. In accord with these findings, the food questionnaires indicated that 11 (39%) patients received less than the recommended daily vitamin B12, and 20 (71%) received less vitamin B6 than recommended. A significant association was found between reduced vitamin B12 intake and both reduced serum cobalamins (p = 0.04) and reduced serum transcobalamin saturation (p = 0.03). Eleven patients took a vitamin pill daily, and these patients had a significantly lower plasma homocysteine compared to the rest. The present study suggests that adult PKU patients were at increased risk of developing vitamin B12 deficiency, and their intake of vitamin B6 was below the recommended daily intake. In conclusion PKU patients need continuing dietary guidance throughout adult life, and considering the risks, costs and potential benefits, daily vitamin supplementation seems justified in these patients.
A study on the nature of genetic metabolic practice at a major paediatric referral centre
Authors: Glass H. C. , Feigenbaum A. , Clarke J. T. R.
Published: April 2006

A retrospective chart review of new paediatric patients seen during the calendar year 1998 by specialists of the Division of Clinical and Metabolic Genetics of the Hospital for Sick Children in Toronto, the largest such referral centre in the country, showed that 81% of specific genetic metabolic diagnoses were made within one month of being seen in consultation by one of the consultants of the programme. In 5% of cases, a specific diagnosis was not reached 4 years after initial consultation. We concluded from this study that the specific diagnosis of inborn errors of metabolism at a major medical genetic referral centre tended to be made quickly, or never. Some of the causes of delays in diagnosis include (1) the lack of ready access to existing diagnostic laboratory testing; (2) technical barriers to the identification of specific metabolic or genetic defects; and (3) incomplete knowledge of genetic defects causing inherited metabolic diseases.
Enzyme replacement therapy and bony changes in Egyptian paediatric Gaucher disease patients
Authors: El‐Beshlawy A. , Ragab L. , Youssry I. , Yakout K. , El‐Kiki H. , Eid K. , Mansour I. M. , El‐Hamid S. Abd , Yang M. , Mistry P. K.
Published: April 2006

Background. In Gaucher disease, the infiltration of the bone marrow by glucocerebroside‐laden macrophages (Gaucher cells) triggers a diverse pattern of skeletal disease that results in crippling complications. Reliable ascertainment of the severity and pattern of skeletal disease is essential to determine disease status and the response to enzyme replacement therapy (ERT). Although there is ample documentation of reversal of haematological and visceral disease by ERT, there is a paucity of data on skeletal response to ERT in children.

Aim. To delineate the pattern of bone disease in children with Gaucher disease in Egypt and to evaluate its response to ERT.

Method. Twenty‐two children with Gaucher disease were treated with ERT. Phenotyping by clinical, laboratory and radiological criteria was performed at baseline and following 11.2 ± 4 months of ERT. Genotyping for glucocerebrosidase (GBA) mutations was performed by gene sequencing, and genotype–phenotype correlations were performed.

Results. Two‐thirds of the patients were from consanguineous pedigrees and 14/22 patients were homozygous or compound heterozygous for L444P and D409H mutations. Bone involvement was detected by plain radiology in 11 children (50%) and in 16 (73%) by magnetic resonance imaging (MRI). There was no correlation of severity of bone involvement and GBA genotype. ERT ameliorated bone disease: 10 of the 11 children with abnormal radiographic findings at baseline showed improvement in skeletal lesions; while 9/16 showed improvement of marrow disease by MRI. Radiographic sensitivity and specificity were 62% and 82% compared to MRI for detection of bone involvement in this patient population. At baseline, bone pain was present in 5 patients and ERT resulted in complete symptomatic remission in all of them. ERT was associated with significant improvement in growth parameters and amelioration of haematological and visceral involvement.

Conclusion. Symptomatic and radiological skeletal disease is common in children with Gaucher disease in Egypt. MRI is the most accurate technique for detecting early skeletal involvement. There was no correlation between severity of skeletal involvement and GBA genotype. ERT was effective in ameliorating radiological manifestations of skeletal disease and achieving complete remission of bone pain.
X‐linked creatine transporter defect: A report on two unrelated boys with a severe clinical phenotype
Authors: Anselm I. M. , Alkuraya F. S. , Salomons G. S. , Jakobs C. , Fulton A. B. , Mazumdar M. , Rivkin M. , Frye R. , Poussaint T. Young , Marsden D.
Published: April 2006

We report two unrelated boys with the X‐linked creatine transporter defect (CRTR) and clinical features more severe than those previously described with this disorder. These two boys presented at ages 12 and 30 months with severe mental retardation, absent speech development, hypotonia, myopathy and extra‐pyramidal movement disorder. One boy has seizures and some dysmorphic features; he also has evidence of an oxidative phosphorylation defect. They both had classical absence of creatine peak on brain magnetic resonance spectroscopy (MRS). In one, however, this critical finding was overlooked in the initial interpretation and was discovered upon subsequent review of the MRS. Molecular studies showed large genomic deletions of a large part of the 3′ end of the complete open reading frame of the SLC6A8 gene. This report emphasizes the importance of MRS in evaluating neurological symptoms, broadens the phenotypic spectrum of CRTR and adds knowledge about the pathogenesis of creatine depletion in the brain and retina.
A single‐residue mutation, G203E, causes 3‐hydroxy‐3‐methylglutaric aciduria by occluding the substrate channel in the 3D structural model of HMG‐CoA lyase
Authors: Mir C. , Lopez‐Viñas E. , Aledo R. , Puisac B. , Rizzo C. , Dionisi‐Vici C. , Deodato F. , Pié J. , Gomez‐Puertas P. , Hegardt F. G. , Casals N.
Published: April 2006

3‐Hydroxy‐3‐methylglutaric aciduria is a rare autosomal recessive genetic disorder that affects ketogenesis and leucine metabolism. The disease is caused by mutations in the gene coding for 3‐hydroxy‐3‐methylglutaryl‐coenzyme A lyase (HL). To date 26 different mutations have been described. A (βα)8 TIM barrel structure has been proposed for the protein, and almost all missense mutations identified so far localize in the beta sheets that define the inside cavity. We report an Italian patient who bears homozygously a novel HL mutation, c.608G > A (p. G203E) in beta sheet six. A structural model of the mutated protein suggests that glutamic acid 203 impedes catalysis by blocking the entrance to the inner cavity of the enzyme. Loss of functionality has been confirmed in expression studies in E. coli, which demonstrate that the G203E mutation completely abolishes enzyme activity. Beta sheet six and beta sheet two are the two protein regions that accumulate most missense mutations, indicating their importance in enzyme functionality. A model for the mechanism of enzyme function is proposed.
Biochemical compared to molecular diagnosis in acute intermittent porphyria
Authors: Groß U. , Puy H. , Jacob K. , Deybach J. C. , Kremer J. , Doss M. O.
Published: April 2006

The biochemical and the molecular diagnoses of an inherited porphyria require experience. False positive or negative screening tests and the low penetrance of the disease make a correct diagnosis difficult.The biochemical and the molecular procedures for the diagnosis of acute intermittent porphyria were applied to five unrelated patients suffering from acute intermittent porphyria. All patients were shown to be gene carriers of acute intermittent porphyria by both methods. The two different possibilities of the diagnosis corresponded well. In a family definitively identified by molecular diagnosis of one of the patients and his relatives, the patient's two children were asymptomatic. His son was shown to be a gene carrier of the father's deficiency by biochemical as well as molecular analysis, whereas his daughter was not affected by acute intermittent porphyria.
Biochemical and molecular diagnosis of lipoamide dehydrogenase deficiency in a North American Ashkenazi Jewish family
Authors: Sansaricq C. , Pardo S. , Balwani M. , Grace M. , Raymond K.
Published: April 2006

A late‐onset presentation of lipoamide dehydrogenase (E3) deficiency is described in a North American Ashkenazi Jewish (AJ) family. Diagnosis was made by urine organic acid and molecular analyses.