bluuebunny/crossref_metadata_2025 huggingface dataset:
Porous Polymers: Enabling Solutions for Energy Applications
Authors: Thomas Arne , Kuhn Pierre , Weber Jens , Titirici Maria‐Magdalena , Antonietti Markus
Published: February 2009

A new generation of porous polymers was made for various energy‐related applications, e.g., as fuel cell membranes, as electrode materials for batteries, for gas storage, partly from renewable resources. This review intends to catch this emerging field by reporting on a variety of different approaches to make high performing polymers porous. This includes template techniques, polymers with inherent microporosity, polymer frameworks by ionothermal polymerization, and the polymerization of carbon from appropriate precursors and by hydrothermal polymerization. In this process, we try to not only identify the current status of the field, but also point to open question and tasks to identify the potentially relevant progress.

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R&D investment as a signal in corporate takeovers
Authors: Socorro M. Pilar
Published: February 2009

The purpose of this paper is to analyze the effects that takeover threats have on firms' preacquisition R&D intensity. Critics of takeovers usually argue that takeover threats may reduce target firms' R&D investments. However, I find that target firms may increase R&D investment in order to signal their compatibility with the acquiring firm. The identity of the acquired firm depends on the market size and target firms' efficiency and compatibility. Through R&D investments, target firms may affect this result, signaling potential outsiders the kind of competition they may face, and forcing them to accept lower takeover offers. Copyright © 2009 John Wiley & Sons, Ltd.
Macromol. React. Eng. 1/2009
Authors: Chatzidoukas Christos , Pistikopoulos Stratos , Kiparissides Costas
Published: February 2009

Cover: Current market demand for tailor‐made polyolefins combined with the need for a more flexible production scheme comprising a large number of polymer grades (e.g., 30–40) force the polyolefin industry to follow an optimal multiproduct plant dynamic operation and grade production sequence. Further details can be found in the article by C. Chatzidoukas, S. Pistikopoulos, C. Kiparissides* on page 36.
Flow‐induced disturbances in balanced steady‐state free precession images: Means to reduce or exploit them
Authors: Lagerstrand K.M. , Plewes D.B. , Vikhoff‐Baaz B. , Forssell‐Aronsson E.
Published: February 2009

In this work computer simulations and phantom measurements are presented that show the effect of flow on in‐plane balanced steady‐state free precession images. The images were studied for various flow velocities, excitation regions, relaxation times, RF‐pulse angles, and off‐resonance frequencies. The work shows that flow‐induced disturbances are present in the images, but can be reduced by the application of inhomogeneous excitation regions. Also, a velocity quantification method that utilizes the disturbances was developed and proved to quantify flow velocities accurately. The work concluded that the flow‐induced disturbances can be reduced to improve image quality, but can also be exploited to quantify the flow velocity. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Ultrashort T relaxometry for quantitation of highly concentrated superparamagnetic iron oxide (SPIO) nanoparticle labeled cells
Authors: Liu Wei , Dahnke Hannes , Rahmer Juergen , Jordan E. Kay , Frank Joseph A.
Published: February 2009

A new method was developed to measure ultrashort T relaxation in tissues containing a focal area of superparamagnetic iron oxide (SPIO) nanoparticle‐labeled cells in which the T decay is too short to be accurately measured using regular gradient echo T mapping. The proposed method utilizes the relatively long T2 relaxation of SPIO‐labeled cells and acquires a series of spin echo images with the readout echo shifted to sample the T decay curve. MRI experiments in phantoms and rats with SPIO‐labeled tumors demonstrated that it can detect ultrashort T down to 1 ms or less. The measured T values were about 10% higher than those from the ultrashort TE (UTE) technique. The shorter the TE, the less the measurements deviated from the UTE T mapping. Combined with the regular T mapping, this technique is expected to provide quantitation of highly concentrated iron‐labeled cells from direct cell transplantation. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Reliability, validity and responsiveness of a new leisure index: The Patient‐Specific Leisure Scale (PSLS)
Authors: Wikström Ingegerd , Arvidsson Barbro , Nilsson Käth , Roos Ewa , Jacobsson Lennart T.H.
Published: February 2009

Objectives: To investigate the reliability, validity and responsiveness of a new Patient‐Specific Leisure Scale (PSLS), constructed to identify goals and outcomes for individual patients with rheumatoid arthritis (RA).

Methods: Forty‐nine patients with RA were used to evaluate test–retest reliability, and 100 consecutive RA patients were used for construct validity. Twenty‐five RA patients, commencing with treatment on tumour necrosis factor (TNF) inhibitors, were evaluated before the start and after three months of therapy, to test responsiveness. The most important leisure activity (as judged by the patients) was used when evaluating reliability and validity. The perceived difficulty with each activity was scored from 0 to 10 (0 = able to perform activity without difficulty, 10 = unable to perform activity).

Results: Test–retest reliability indicated a good agreement (0.62–0.87) using weighted kappa. Construct validity was demonstrated by modest positive correlation between leisure activity and Health Assessment Questionnaire (HAQ) (rs = 0.27, p = 0.005) visual analogue scale (VAS) pain (rs = 0.28, p = 0.004) VAS global (rs = 0.22, p = 0.027), VAS fatigue (rs = 0.24, p = 0.013), joint index of 28 swollen joints (rs = 0.22, p = 0.027) and negative correlations with short‐form‐36 (SF‐36) physical functioning (rs = −0.18, p = 0.008), bodily pain (rs = −0.31, p < 0.001), general health (rs = −0.23, p = 0.019), vitality (rs = −0.31, p < 0.001), social function (rs = −0.24, p = 0.016) and role‐emotional (rs = −0.28, p = 0.005). Mean improvement for the most important leisure activity was 1.36, (p = 0.036, 95% confidence interval 0.10–2.62). Standardized response mean and effect size for the most important activity in PSLS was 1.05 and 0.72, respectively, and for HAQ 0.34 and 0.28, respectively.

Conclusions: PSLS appears to be feasible, reliable, valid and responsive for measuring leisure activities in RA. It provides both an individual result which is useful in clinical work, and results at a group level. Copyright © 2009 John Wiley & Sons, Ltd.
Application of parameter differentiation for flow of a third grade fluid past an infinite porous plate
Authors: Sajid M.
Published: February 2009

This article investigates the analytic solution for the flow of a third grade fluid past an infinite porous plate. The method of parameter differentiation is used to linearized the governing flow equation. The solution of the obtained linear equation is developed by differential transform method in combination with the method of superposition. The obtained results are compared with existing results in the literature and an excellent agreement is found. This shows that the parameter differentiation is a powerful technique for solving nonlinear problems. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010
Isothermal crystallization of pure and glass fiber reinforced poly(phenylene sulfide) composites
Authors: Zhang Richao , Huang Yigang , Min Min , Gao Yong , Yu Xuejiang , Lu Ai , Lu Zhongyuan
Published: February 2009

The isothermal crystallization of poly(phenylene sulfide) (PPS) and its glass fiber (GF) reinforced composite has been investigated by differential scanning calorimetry (DSC) and polarized optical microscope (POM) equipped with a hot stage. During the isothermal crystallization process of PPS the Avrami exponent value decreases with time, indicating the change of crystallization mechanism and presence of mixed growth mechanism (bidimensional and three‐dimensional growth of crystals). The presence of GF greatly accelerates the bulk crystallization rate of PPS and changes the crystalline morphology of PPS from the spherulites to transcrystallization. And the reason for development of transcrystallization is considered to be relevant with the compatibility of the interface between GF and PPS. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Effect of 3‐propionylthio‐1‐propyltrimethoxylsilane on structure, mechanical, and dynamic mechanical properties of NR/silica composites
Authors: Peng Hualong , Liu Lan , Luo Yuanfang , Wang Xiaoping , Jia Demin
Published: February 2009

Blocked mercaptosilane possessing two functionally active end groups can chemically react with both silica and rubber leading to significant improvement in silica‐filled vulcanizate products. The effect of the novel blocked mercaptosilane (3‐propionylthio‐1‐propyltrimethoxylsilane) (called hereafter PXT) on the structure, mechanical, and dynamic mechanical properties of NR/silica composite were studied. Equilibrium swelling test and scanning electron microscope (SEM) indicate that PXT is able to enhance the crosslinking density of natural rubber (NR)/silica composites and the dispersion of silica in matrix. Mechanical measurement of properties show that PXT can strengthen the reinforcement of silica for NR vulcanizate. In the presence of PXT, the resistance to flex cracking, abrasion and dynamic compression fatigue, and heat build‐up of NR/silica composites can be improved substantially. For the application of automotive tire, it also obtains high‐skid resistance and low‐rolling resistance simultaneously at 2 phr of the PXT concentration. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Anomalies, influencing factors, and guidelines for DMA testing of fiber reinforced composites
Authors: Swaminathan Gowthaman , Shivakumar Kunigal N. , Russell Larry C.
Published: February 2009

This study systematically assessed the measurement of dynamic properties of a range of fiber reinforced composite materials using dynamic mechanical analysis (DMA) instrument. The discrepancy in the moduli from DMA to ASTM tests was investigated. The study showed that proper specimen preparation, maintaining appropriate aspect ratio (span to thickness ratio) to reduce the transverse shear deformation, and sufficient loading are critical to measure correct properties from DMA test. The guidelines on aspect ratio and loading for plastics to high‐modulus carbon fiber composites are presented as a design chart and equations, respectively. The study also found that the glass transition temperature (Tg) was independent of specimen aspect ratio and Tg is lower for multidirectional composites when compared with its unidirectional composites. The particle interleaved T800H/3900‐2 composite showed two glass transition temperatures (140 and 198°C), the lower value is due to the effect of interleaving by thermoplastic particles, and the higher value is the Tg of its base matrix. This lowering of Tg would have significant effect on the application temperature of the material. This phenomenon was not observed here to fore in the literature. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Experimental failure analysis of bolted joints in moisture‐ and temperature‐induced composite laminates under preload
Authors: Gören Aytaç , Sayman Onur
Published: February 2009

In this study, an experimental investigation was carried out in a bolted glass fiber‐reinforced laminate under preload moments. The stacking sequence at the composite laminate was chosen as [90°/0°/45°/−30°]s. The preload moments were selected as 2, 4, and 6 Nm, in order to compare the influence of preload moments on failure modes and strengths. Some specimens were subjected to hot pure water at 70°C for 7 days. The bearing strength in this case was measured again under the same preload moments of 2, 4, and 6 Nm. It is found that the bearing strength of the specimen waited in hot water was 5.4% smaller than that of the specimen in dry condition. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Preparation, characterization, and thermal stability of novel PMMA/expandable graphite halogen‐free flame retardant composites
Authors: Chen Chia‐Hsun , Yen Wei‐Hsin , Kuan Hsu‐Chiang , Kuan Chen‐Feng , Chiang Chin‐Lung
Published: February 2009

In this investigation, expandable graphite was functionalized using a coupling agent to produce covalent bonds between the organic and inorganic phases, enhancing the thermal stability of the composites. The modified expandable graphite had an OEt function group that reacted with methyl methacrylate‐co‐3‐(trimethoxysilyl)propyl methacrylate. Fourier transform‐infrared spectrometry and X‐ray photoelectron spectra were adopted to characterize the grafting reaction between vinyltriethoxysilane and expandable graphite. It is affirmed that VTES has reacted with expandable graphite. The results of thermogravimetric analysis and thermogravimetric difference (TGΔ) reveal that functionalized expandable graphite can improve the thermal stability of composites. Scanning electron microscope was utilized to observe the morphology of the composites, and the behavior of expansion was discussed after the materials were burned. These results of X‐ray photoelectron spectra for char confirm that expandable graphite improves the degree of accumulation of char and that of the antioxidation of the composites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Influence of carbon‐based nanofillers on the electrical and dielectric properties of ethylene vinyl acetate nanocomposites
Authors: George Jinu Jacob , Bhadra Sambhu , Bhowmick Anil K.
Published: February 2009

A comparative study of ethylene vinyl acetate nanocomposites based on expanded graphite, multiwalled carbon nanotubes, and carbon nanofibers has been carried out to investigate the effect of different carbon nanofillers on the electrical properties of the corresponding composites. The composites were prepared by ultrasonic dispersion of fillers in ethylene vinyl acetate solution, followed by casting and compression molding. The dependence of AC conductivity and dielectric constant on the frequency and filler concentration was investigated. Carbon nanofibers provided maximum conductivity as well as lowest percolation threshold (8.2 vol%) compared to expanded graphite and multiwalled carbon nanotubes filled composites. The improvement in both electrical conductivity and dielectric constant was attributed to the high filler aspect ratio and the formation of conducting networks. The relationship of dielectric constant with filler volume fraction for all the composite systems is estimated using a power law. The pressure sensing capability of the composites at respective percolation thresholds was also compared. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Study on dispersion and intercalation of organoclay in PP and PP‐g‐MA matrices
Authors: Hedayati A. , Arefazar A.
Published: February 2009

Understanding the complex mechanism of dispersion and intercalation of the clay tactoids can allow us to control the final morphology, homogeneity, and the macroscopic properties of clay nanocomposites. The objective of this work is a multiscale study of the dispersion state of PP/organoclay and PP‐g‐MA/organoclay composite. The microscopic investigation, WAXS diffractograms, rheological analysis, and mechanical properties were used to characterize the dispersion of organoclay in PP and PP‐g‐MA matrices during melt blending in two different shear rates. The morphological results show a system of aggregating intercalated clay particles which disperse by increasing mixing time with a strain‐controlled process and a very quick intercalation process in early mixing times for PP‐g‐MA/organoclay nanocomposite, while PP/organoclay samples only form microcomposites. The relative network modulus of these intercalated particles as a function of mixing time was obtained; and the tensile modulus of nanocomposite samples were compared with Halpin‐Tsai model prediction. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Flame resistance and foaming properties of NBR compounds with halogen‐free flame retardants
Authors: Moon SungCheal , Jo ByungWook , Farris Richard J.
Published: February 2009

Acrylonitrile butadiene rubber (NBR) foams compounded with various halogen‐free flame retardants were prepared. The influence of nonhalogen flame retardants on the flame resistance and foaming properties of the NBR compounds were investigated. The foaming properties (expandability 980%–1050%, closed‐cell structure) of NBR compounds with expandable graphite (EG) and ammonium polyphosphate (APP) flame retardants were similar to the NBR base compounds which contained primarily aluminum hydroxide (ATH). The heat release capacity (HRC) ranged from 10 to 74 J/g‐K, the average heat release rate (A‐HRR) ranged from 8 to 60 kW/m2, and the total heat release (THR) ranged from 2.6 to 7.3 MJ/m2 for the nonhalogenated NBR foams with closed‐cell structure and were significantly decreased upon increasing the amounts of flame retardants. This reduction is attributed to the hard char formation and production of water from the interaction with ATH. The limiting oxygen index (LOI) and time to ignition (TTI) show opposite results. The smoke density (0.050–0.037) of the NBR foams with EG flame retardant was decreased when compared to the NBR foam (0.107). The EG flame retardant was more effective than the phosphorus/nitrogen flame retardants in reducing the HRR and smoke density. The use of both ATH and EG is very effective in improving flame resistance. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Strength improvement of iPP/MWCNT nanocomposites
Authors: Ritter U. , Scharff P. , Dmytrenko O.P. , Kulish N.P. , Prylutskyy Yu. I. , Grabovskiy Yu. E. , Belyi N.M. , Pinchuk T.N. , Alekseev A.N. , Sementsov Yu. I. , Gavrylyuk N.A. , Shlapatskaya V.V.
Published: February 2009

The mechanisms of microhardness increase in thermoplastic polypropylene/multi‐walled carbon nanotubes (MWCNT) nanocomposites during electron irradiation (Ee = 1.8 MeV) with different absorption doses are investigated. The crystal structure of the nanocomposites, Raman scattering, and microhardness in a MWCNT concentration range between 0.1 and 5.0 wt% is studied in detail. During irradiation, changes in the degree of crystallinity of the polymer matrix, lattice parameters of the topologically ordered phase, Raman scattering, and microhardness show a complex conjugation process between the composite components. Their interaction is accomplished as the result of the formation of new bonds, which appeared with the radiation damages. Furthermore, the crosslinking of the internal MWCNT layers also contributes to an increase in the strength properties of the polymer nanocomposites. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
The composition, morphology, and mechanical properties of ethylene propylene diene monomer‐encapsulated coal gangue powder/polypropylene composites
Authors: Liu Ying , Xie Bang‐Hu , Yang Wei , Yang Ming‐Bo
Published: February 2009

The ternary composites of coal gangue powder encapsulated by ethylene propylene diene monomer (EPDM) filled polypropylene (PP) were prepared to reduce the cost and control the microstructure aiming at high performance cost ratio materials. The result showed that EPDM can not only enhance the interaction between coal gangue powder and the matrix but also promote the dispersion of coal gangue powder. With the addition of coal gangue encapsulated by EPDM, the impact strength of composition dropped greatly, but it still kept about 11 kJ/m2 when the content of encapsulated coal gangue powder is more than 18 wt%. The tensile strength and fracture toughness (we) also dropped with the addition of encapsulated coal gangue powder, but only a small drop occurred when the content of encapsulated coal gangue powder is less than 18 wt% and great drop emerged when the content is larger than 18 wt%. Compared with coal gangue powder/PP binary composition, the ternary compositions involve higher content of coal gangue powder but present better properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Synthesis, thermal properties, and flame retardance of phosphorus‐containing epoxy‐silica hybrid resins
Authors: Yu Dan , Liu Weiqu , Liu Yunfeng
Published: February 2009

A novel epoxy resin modifier, phosphorus‐containing epoxide siloxane (DPS) with cyclic phosphorus groups in the SiO network, was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) with polyhedral‐oligomeric siloxanes, which was synthesized by the sol–gel reaction of 3‐glycidoxypropyltrimethoxysilane. DPS was confirmed by Fourier transform infrared and 29Si NMR measurement, and then was employed to modify epoxy resin at various ratios, with 4,4‐diaminodiphenyl‐methane as a curing agent. In order to make a comparison, DOPO‐containing epoxy resins were also cured under the same conditions. The resulting organic–inorganic hybrid epoxy resins modified with DPS exhibited a high glass transition temperature (Tg), a good thermal stability, and a high limited oxygen index. In addition, the tensile strength of cured products was also rather desirable. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Effect of external electric field on the microstructures and properties of carbon nanotubes/thermosets nanocomposites
Authors: Duan Jingkuan , Kim Chonung , Jiang Pingkai
Published: February 2009

The alignment of multiwalled carbon nanotubes (MWCNTs) and thermosetting resins in nanocomposites based on field‐aided micro‐tailoring (FAiMTa) technology was studied by means of scanning electric microscopy (SEM), Raman spectroscopy, and atomic force microscopy (AFM), and the effect of the different values of electric field intensity on the changes of the microstructures and properties of nanocomposites were presented. The experimental results implied that the electric field encouraged the molecular alignment of polymers and MWCNTs orientation within the polymeric matrices along the field direction during their curing stages. It was found that the extents of their orientation and alignment were closely dependent on the external electric field intensity by means of Raman spectroscopy and AFM measurements. The thermal and dielectric properties of nanocomposites were examined by thermogravimetric analysis (TGA) and dielectric analysis (DEA), respectively. The TGA and DEA measurements revealed substantial differences in the thermal and dielectric behaviors for the thermoelectrically processed nanocomposites. These differences could be ascribed to the microstructural changes of matrix at the molecular level and the alignment of nanofillers. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Dynamic and capillary rheology of LDPE‐EVA–based thermoplastic elastomer: Effect of silica nanofiller
Authors: Hui Shalmali , Chaki Tapan K. , Chattopadhyay Santanu
Published: February 2009

The effect of pristine silica nanoparticles on the dynamic and capillary rheology of a model LDPE‐EVA thermoplastic elastomeric system is explored in this paper. The pristine silica nanoparticles were melt‐blended with the LDPE‐EVA system at 1.5, 3, and 5 wt% loadings, respectively, by varying the sequence of addition. In one of the compositions, coupling agent bis‐[3‐(triethoxysilyl)propyl] tetrasulphide (Si‐69) was used to improve the interaction of hydrophilic silica particles with polymer matrix. Results obtained reveal that the viscoelastic behavior of such composites is influenced remarkably by loadings of silica, variation of sequence, and addition of Si‐69. Upon addition of coupling agent, G′ value increases especially at higher strain levels due to increased polymer‐filler interactions. All systems with various loading of nanosilica represent an increase in elastic response with increasing frequency. Both the unfilled and filled blends exhibit rheological behavior of non‐Newtonian fluids. But interestingly, the viscoelastic response varies markedly with the temperature. The dynamic and steady shear rheological properties register a good correlation in regard to the viscous vs. elastic response of such systems. Finally, the rheological behavior is correlated with morphology of the present system processed at various shear rates. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Environmental effects on glass fiber reinforced polypropylene thermoplastic composite laminate for structural applications
Authors: Robert Mathieu , Roy René , Benmokrane Brahim
Published: February 2009

This article presents the mechanical and microstructural characterization of glass fiber reinforced polypropylene thermoplastic composite laminates (PP/Glass) exposed to tap water, salt solution, and freeze/thaw cycles. PP/Glass specimens were immersed at 23, 50, and 70°C in tap water to simulate the relative humidity of the direct environment and in a salt solution of 3% NaCl to simulate the effect of de‐icing salt. The measured flexural strengths of the specimens before and after exposure were considered as a measure of the durability performance of the specimens and were used for long‐term properties prediction based on the Arrhenius theory. In addition, the durability of PP/Glass to freeze/thaw cycles was studied for as received specimens and specimens saturated with tap water. Scanning electron microscopy was also used to characterize the effect of aging on the PP/Glass specimens. The results showed that the durability of PP/Glass composite is related to the quality of their consolidation. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Analysis of fire calls to an industrial complex over a 12‐year period
Authors: Cadwallader L.C.
Published: February 2009

This article gives an analysis of fire calls from over a decade of operations at a process facility complex operated by the Idaho National Laboratory. These data include valid alarms, unwanted or false alarms, ambulance calls, and hazardous material cleanup calls. Of special interest are false alarms, which are not only a nuisance to facility productivity but also are detrimental to public and facility safety. Of the fire calls listed here, over half were from false alarms. The results given are compared with National Fire Protection Association data. The data presented can serve as exemplar data for future facilities and can be compared with other operating facilities' experiences. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009
Modeling longitudinal count data with dropouts
Authors: Alosh Mohamed
Published: February 2009

This paper explores the utility of different approaches for modeling longitudinal count data with dropouts arising from a clinical study for the treatment of actinic keratosis lesions on the face and balding scalp. A feature of these data is that as the disease for subjects on the active arm improves their data show larger dispersion compared with those on the vehicle, exhibiting an over‐dispersion relative to the Poisson distribution. After fitting the marginal (or population averaged) model using the generalized estimating equation (GEE), we note that inferences from such a model might be biased as dropouts are treatment related. Then, we consider using a weighted GEE (WGEE) where each subject's contribution to the analysis is weighted inversely by the subject's probability of dropout. Based on the model findings, we argue that the WGEE might not address the concerns about the impact of dropouts on the efficacy findings when dropouts are treatment related. As an alternative, we consider likelihood‐based inference where random effects are added to the model to allow for heterogeneity across subjects. Finally, we consider a transition model where, unlike the previous approaches that model the log‐link function of the mean response, we model the subject's actual lesion counts. This model is an extension of the Poisson autoregressive model of order 1, where the autoregressive parameter is taken to be a function of treatment as well as other covariates to induce different dispersions and correlations for the two treatment arms. We conclude with a discussion about model selection. Published in 2009 by John Wiley & Sons, Ltd.
Gloss phenomena and image analysis of atomic force microscopy in molecular and cell biology
Authors: Zhu Jie , Sabharwal Tanya , Guo Lianhong , Kalyanasundaram Aruna , Wang Guodong
Published: February 2009

Proper sample preparation, scan setup, data collection and image analysis are key factors in successful atomic force microscopy (AFM), which can avoid gloss phenomena effectively from unreasonable manipulations or instrumental defaults. Fresh cleaved mica and newly treated glass cover were checked first as the substrates for all of the sample preparation for AFM. Then, crystals contamination from buffer was studied separately or combined with several biologic samples, and the influence of scanner, scan mode and cantilever to data collection was also discussed intensively using molecular and cellular samples. At last, images treatment and analysis with off‐line software had been focused on standard and biologic samples, and artificial glosses were highly considered for their high probability. SCANNING 31: 49–58, 2009. © 2009 Wiley Periodicals, Inc.
Confocal scanning optical microscopy of a 3‐million‐year‐old Australopithecus afarensis femur
Authors: Bromage T. G. , Goldman H. M. , McFarlin S. C. , Perez Ochoa A. , Boyde A.
Published: February 2009

Portable confocal scanning optical microscopy (PCSOM) has been specifically developed for the noncontact and nondestructive imaging of early human fossil hard tissues, which here we describe and apply to a 3‐million‐year‐old femur from the celebrated Ethiopian skeleton, “Lucy,” referred to Australopithecus afarensis. We examine two bone tissue parameters that demonstrate the potential of this technology. First, subsurface reflection images from intact bone reveal bone cell spaces, the osteocyte lacunae, whose density is demonstrated to scale negatively with body size, reflecting aspects of metabolism and organismal life history. Second, images of a naturally fractured cross section near to Lucy's femoral mid‐shaft, which match in sign those of transmitted circularly polarized light, reveal relative collagen fiber orientation patterns that are an important indicator of femoral biomechanical efficacy. Preliminary results indicate that Lucy was characterized by metabolic constraints typical for a primate her body size and that in her femur she was adapted to habitual bipedalism. Limitations imposed by the transport and invasive histology of unique or rare fossils motivated development of the PCSOM so that specimens may be examined wherever and whenever nondestructive imaging is required. SCANNING 31: 1–10, 2009. © 2009 Wiley Periodicals, Inc.
Effect of fabrication process parameters on the apex‐radius of STM tungsten nanotip
Authors: Tahmasebipour Gh. , Hojjat Y. , Ahmadi V. , Abdullah A.
Published: February 2009

Scanning tunneling microscope (STM) has found a wide application in nanoscience and nanotechnology. This microscope uses an ultra‐sharp metallic tip for image acquisition. Resolution of STM images depends largely on the radius of the tip apex; the smaller the radius the higher the resolution. In the present research, an experimental set‐up was designed and implemented for fabrication of STM tungsten nanotip using electrochemical‐etching method with the aim of optimization of nanotip fabrication process parameters by using Taguchi method. These parameters are electrolyte concentration, immersion length of the tungsten wire, inner diameter of the cathode tube, and the process voltage. It was found that the optimum level of the process parameters for gaining minimum radius of the nanotip apex is electrolyte concentration of 2 M/lit, wire immersion length of 4 mm, cathode tube inner diameter of 55 mm, and voltage of 3.5 V within the range of experiments. By setting the process parameters on the optimum level, the radius of the nanotip apex was decreased by five times in comparison to the mean value of the experimental results. The radius of the nanotip apex was improved down to about 10 nm under the optimum conditions. SCANNING 31: 65–74, 2009. © 2009 Wiley Periodicals, Inc.
Cerebral biometry in fetal magnetic resonance imaging: new reference data
Authors: Tilea B. , Alberti C. , Adamsbaum C. , Armoogum P. , Oury J. F. , Cabrol D. , Sebag G. , Kalifa G. , Garel C.
Published: February 2009

Objectives

To provide normal magnetic resonance imaging (MRI) reference biometric data of the fetal brain, to evaluate reproducibility and gender effect, to compare the two cerebral hemispheres and to compare MRI with ultrasonographic biometry, in a large cohort.

Methods

Normal cerebral fetal MRI examinations were collected prospectively and several parameters were measured: the supratentorial space (bone and cerebral fronto‐occipital and biparietal (BPD) diameters), the length of the corpus callosum (LCC), the surface area, height and anteroposterior diameter of the vermis, the transverse cerebellar diameter (TCD) and the anteroposterior diameter of the pons. We evaluated the interobserver reproducibility of measurements and the possible gender effect on measurements of bone BPD, TCD and LCC. We compared right and left hemispheres, right and left atria and ultrasound and MRI measurements.

Results

The study included 589 fetuses, ranging from 26 to 40 weeks. Normal values (from 3rd to 97th percentile) are provided for each parameter. Interobserver agreement was excellent, with an intraclass correlation coefficient (ICC) > 0.75 for many parameters. The gender effect was evaluated in 372 cases and did not reveal any clinically meaningful difference. Comparison between the right and left cerebral hemispheres and between the right and left atria did not reveal any meaningful differences. Ultrasound and MRI measurements of BPD and TCD were compared in 94 cases and 48 cases, respectively, and the agreement was excellent (ICC = 0.85).

Conclusions

We present new reproducible reference charts for cerebral MRI biometry at 26–40 weeks' gestation, from a large cohort of fetuses. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Anatomic Significance of a Positive Barium Enema in Deep Infiltrating Endometriosis of the Large Bowel
Authors: Anaf Vincent , Nakadi Issam El , De Moor Veronique , Coppens Emmanuel , Zalcman Marc , Noel Jean‐Christophe
Published: February 2009

Purpose

The anatomopathological significance of a positive double‐contrast barium enema (DCBE) for suspicion of deep infiltrating endometriosis of the large bowel was studied. This is a retrospective study of a prospective database.

Methods

A large‐bowel resection was proposed for patients who were suspicious for large‐bowel endometriosis and had a positive DCBE. In a series of 73 patients, 71 large‐bowel resections were performed. Histology and immunohistochemistry with the monoclonal antibody CD‐10 were performed on the resection specimen. Outcome measures were the length of the resected specimen, the largest diameter of the lesion, the positivity of the resection margins, and the degree of infiltration of the large bowel. We also compared the mean largest diameters of the lesions with the degree of infiltration of the large bowel.

Results

Between December 1997 and October 2005, 80 patients were suspicious for large‐bowel endometriosis: 73 (91%) had positive DCBEs, and 7 (9%) had negative DCBEs. Of the 73 with positive DCBEs, 4 (5%) refused digestive resection and 1 (1.4%) was excluded. Three patients underwent two large‐bowel resections because of the presence of bifocal lesions (left and right colon). A total of 71 resections were performed. In case of positive DCBE, the perivisceral fat and the whole muscularis were infiltrated in 100% of cases. The infiltration reached the submucosa and the mucosa respectively in 82% and 18% of cases. A total of 9.9% of resection margins were positive at histology but only focally. The mean largest diameter of the lesions infiltrating the whole thickness of the large bowel was not statistically different from the mean largest diameter of more superficial lesions.

Conclusions

Findings of mass effect with indentations and ridging of the mucosa on DCBE in a setting suspicious for large‐bowel endometriosis correspond well with pathologic findings of deep infiltration of the large‐bowel wall. Clinicians dealing with deep infiltrating endometriosis should be aware of these findings, which could influence their choice of surgical treatment.
Does habitat structure matter? Spatially explicit population modelling of an Iberian gypsum endemic
Authors: Quintana‐Ascencio Pedro Francisco , Caballero Idoia , Olano José Miguel , Escudero Adrián , Albert Maria José
Published: February 2009

Habitat heterogeneity may influence plant demography because conditions for survival, growth, and reproduction vary within a species’ range. We assessed the role of microhabitat spatial structure on the demography of Helianthemum squamatum, a shrubby gypsum specialist endemic to the Iberian Peninsula. We evaluated the demographic effect of microhabitat spatial variation using an approach that combined cellular automata with matrix population models, and included environmental and demographic stochasticty. We collected data on seed bank (2003–2005), seedling emergence (2003–2006), and adult survivorship (2004–2007) for H. squamatum in two independent blocks with different grazing intensity in Belinchón (Cuenca, Spain). We built spatial scenarios for each block based on field data of cover and spatial pattern of four microhabitats: lichenic crust, litter, H. squamatum, and shrub. Seedling survivorship was affected by year, block, and microhabitat, with individuals emerging under conspecifics having the highest survival rate and on litter the lowest in both blocks, whereas the effect of crust and other shrubs differed across blocks. Our models indicated population increase in the block with low grazing, but population decline in the block with intense grazing. We hypothesize that higher pressure of livestock grazing and trampling leads to a shift in relative microhabitat suitability for crust and shrub. This potential effect of grazing on spatial demographic variation opens interesting questions for future research. We emphasize the importance of considering microhabitat spatial structure when evaluating management and conservation strategies.
Brain dysfunction in phenylketonuria: Is phenylalanine toxicity the only possible cause?
Authors: van Spronsen F. J. , Hoeksma Marieke , Reijngoud Dirk‐Jan
Published: February 2009

In phenylketonuria, mental retardation is prevented by a diet that severely restricts natural protein and is supplemented with a phenylalanine‐free amino acid mixture. The result is an almost normal outcome, although some neuropsychological disturbances remain. The pathology underlying cognitive dysfunction in phenylketonuria is unknown, although it is clear that the high plasma concentrations of phenylalanine influence the blood–brain barrier transport of large neutral amino acids. The high plasma phenylalanine concentrations increase phenylalanine entry into brain and restrict the entry of other large neutral amino acids. In the literature, emphasis has been on high brain phenylalanine as the pathological substrate that causes mental retardation. Phenylalanine was found to interfere with different cerebral enzyme systems. However, apart from the neurotoxicity of phenylalanine, a deficiency of the other large neutral amino acids in brain may also be an important factor affecting cognitive function in phenylketonuria. Cerebral protein synthesis was found to be disturbed in a mouse model of phenylketonuria and could be caused by shortage of large neutral amino acids instead of high levels of phenylalanine. Therefore, in this review we emphasize the possibility of a different idea about the pathogenesis of mental dysfunction in phenylketonuria patients and the aim of treatment strategies. The aim of treatment in phenylketonuria might be to normalize cerebral concentrations of all large neutral amino acids rather than prevent high cerebral phenylalanine concentrations alone. In‐depth studies are necessary to investigate the role of large neutral amino acid deficiencies in brain.
PKU—What is daily practice in various centres in Europe?
Authors: van Spronsen F. J. , Ahring K. Kiær , Gizewska M.
Published: February 2009

Background:

Since the start of the European Society of Phenylketonuria and Allied Disorders Treated as Phenylketonuria (ESPKU) in 1987, an increasing number of parental organizations of member countries have joined. Treatment varies widely within Europe. A survey among professionals was done to determine goals and practice.

Method:

In 2005, a questionnaire was sent to professionals of member countries, addressing diagnostic and treatment procedures, numbers of patients necessary for a PKU centre, guidelines followed, numbers of patients treated and professionals involved in care, target phenylalanine concentrations, amount of protein prescribed, frequency of monitoring and clinical visits, need for follow‐up of various clinical and biochemical data, the importance of various abnormalities, and definition of (non)compliance.

Results:

Seventeen centres of 12 countries answered. Professionals of 13 countries could not be reached or did not respond. Differences in care were observed in many issues of care including target phenylalanine concentrations. Only few issues had general consensus.

Conclusion:

Not all countries were really active at ESPKU level. In the active countries, a professional could not always be contacted. Responses show that PKU care varies largely between European countries. Notwithstanding the large diversity on many issues of day‐to‐day care and therapeutic targets, results showed increasing consensus on some issues. The most important outcome of this questionnaire might be that the Scientific Advisory Committee of the ESPKU initiated meetings for professionals of different backgrounds taking care of PKU patients besides the already existing programme for parents, patients and delegates. Discussion among these professionals may improve quality of care.
Chemical Composition and Nutritional Characteristics of the Seed Oil of Wild Lathyrus, Lens and Pisum Species from Southern Spain
Authors: Pastor‐Cavada Elena , Juan Rocio , Pastor Julio E. , Alaiz Manuel , Vioque Javier
Published: February 2009

The fatty acid composition of the seed oil of 19 wild legume species from southern Spain was analyzed by gas chromatography. The main seed oil fatty acids ranged from C14:0 to C20:0. Among unsaturated fatty acids, the most abundant were linoleic, oleic and linolenic acids, except for Lathyrus angulatus, L. aphaca, L. clymenum, L. sphaericus and L. nigricans where C18:3 contents were higher than C18:1 contents. Palmitic acid was the most abundant saturated acid in studied species, ranging from 11.6% in Lathyrus sativus to 19.3% in Lens nigricans. All studied species showed higher amounts of total unsaturated fatty acids than saturated ones. Among studied species, the ω6/ω3 ratio was variable, ranging from 2.0% in L. nigricans to 13.8% in L. sativus, there being eight species in which the ω6/ω3 ratio was below 5. The fatty acids observed in these plants supports the use of these plants as a source of important dietary lipids.
A rare pentad of foot and ankle deformities in hyperlax children
Authors: Ilyas I. , Wade W. J. , Al Barrag M. , Al Hussainan T. S. , lotaibi L. A. , Alssayad M.
Published: February 2009

Objective

The aim of this paper is to describe the clinical features and radiological appearance of a rare and complex lower leg and foot deformity in hyperlax children.

Methods

Four children were included in the study; of these, two had bilateral feet involvement. All deformities were present since birth, comprising a pentad of conditions: (1) pathologic external tibia and fibula torsion, (2) ball and socket ankle joint with medial subluxation and talus medial subluxation, (3) excessive hindfoot valgus, (4) peroneal and Achilles tendon displacement anterior to the lateral malleolus and (5) generalized ligament laxity. All children had failed cast manipulation. Only two had undergone a minimal soft tissue procedure, but there had been no improvement.

Results

All patients were ambulatory and pain free at the mean age of 6.5 years.

Conclusion

Conservative or minimal soft tissue procedures are not effective in restoring the anatomy of such feet.
Conformational changes in p47phox upon activation highlighted by mass spectrometry coupled to hydrogen/deuterium exchange and limited proteolysis
Authors: Marcoux Julien , Man Petr , Castellan Mathieu , Vivès Corinne , Forest Eric , Fieschi Franck
Published: February 2009

The neutrophil NADPH oxidase is an enzymatic complex involved in innate immunity. Phosphorylation of p47phox promotes its translocation with p67phox and p40phox, followed by membrane interaction and assembly with flavocytochrome b
558 into a functional complex. To characterise p47phox conformational changes during activation, we used wild‐type and the S303/304/328E triple mutant mimicking the phosphorylated state. Hydrogen/deuterium exchange and limited proteolysis coupled to mass spectrometry were used to discriminate between the various structural models. An increase in deuteration confirmed that p47phox adopts an open and more flexible conformation after activation. Limited proteolysis correlated this change with increased auto‐inhibitory region (AIR) accessibility. These results establish a structural link between the AIR release and the exposure of the Phox homology (PX) domain.
Silicate bioweathering and biomineralization in lacustrine microbialites: ancient analogues from the Miocene Duero Basin, Spain
Authors: SANZ-MONTERO M. ESTHER , RODRÍGUEZ-ARANDA J. PABLO
Published: February 2009

The Miocene dolomite-chert microbialites studied here offer a complete record of the geochemical cycles of silicate weathering and the subsequent formation of secondary products. The microbialites were formed in lacustrine systems during the Miocene of the Duero Basin, central Spain. Mineralogical, chemical and petrographic results provide evidence of the mediation of microbes in early weathering and by-product formation processes. Irrespective of the composition, the surfaces of the grains were subject to microbial attachment and concomitant weathering. Palaeo-weathering textures range from surface etching and pitting to extensive physical disaggregation of the minerals. Extreme silicate weathering led to the complete destruction of the silicate grains, whose prior existence is inferred from pseudomorphs exhibiting colonial textures like those recognized in the embedding matrix. Detailed petrographic and microanalytical examinations of the weathering effects in K-feldspars show that various secondary products with diverse crystallinity and chemical composition can coexist in the interior of a mineral. The coexistence of by-products is indicative of different microenvironmental conditions, likely created by microbial reactions. Thus, the presence of varied secondary products can be used as a criterion of biogenicity. Intensive alteration of P-bearing feldspars suggests that mineral weathering may have been driven by the nutrient requirements of the microbial consortium involved in the precipitation of dolomite. The rock record provides useful information on mineral weathering mediated by microbes.