bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of nanomaterials for bone repair and regeneration
Authors: McMahon Rebecca E. , Wang Lina , Skoracki Roman , Mathur Anshu B.
Published: December 2012

Bone is a nanocomposite composed of organic (mainly collagen) and inorganic (nanocrystalline hydroxyapatite) components, with a hierarchical structure ranging from nano‐ to macroscale. Its functions include providing mechanical support and transmitting physio‐chemical and mechano‐chemical cues. Clinical repair and reconstruction of bone defects has been conducted using autologous and allogeneic tissues and alloplastic materials, with functional limitations. The design and development of biomaterial scaffolds that will replace the form and function of native tissue while promoting regeneration without necrosis or scar formation is a challenging area of research. Nanomaterials and nanocomposites are promising platforms to recapitulate the organization of natural extracellular matrix for the fabrication of functional bone tissues because nanostructure provides a closer approximation to native bone architecture. Nanostructured scaffolds provide structural support for the cells and regulate cell proliferation, differentiation, and migration, which results in the formation of functional tissues. Unique properties of nanomaterials, such as increased wettability and surface area, lead to increased protein adsorption when compared with conventional biomaterials. Cell–scaffold interactions at the cell–material nanointerface may be mediated by integrin‐triggered signaling pathways that affect cell behavior. The materials selection and processing techniques can affect the chemical, physical, mechanical, and cellular recognition properties of biomaterials. In this article, we focused on reviewing current fabrication techniques for nanomaterials and nanocomposites, their cell interaction properties and their application in bone tissue engineering and regeneration. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
In vitro bioactivity and cytocompatibility properties of spark plasma sintered HA‐Ti composites
Authors: Kumar Alok , Dhara Sharmistha , Biswas Krishanu , Basu Bikramjit
Published: December 2012

The present study reports the results of the detailed in vitro bioactivity and cytocompatibility properties of the hydroxyapatite (HA) and the HA‐titanium (HA‐Ti) composite with varying amount of Ti (5, 10, and 20 wt %), densified using spark plasma sintering process (SPS). Using this technique and tailoring suitable processing parameters, it has been possible to retain both HA and Ti in the sintered ceramics. Importantly, the uniquely designed SPS processing with suitably chosen parameters enables in achieving better mechanical properties, such as higher indentation fracture toughness (∼1.5 MPa m1/2) in HA‐Ti composites compared with HA. X‐ray diffraction and scanning electron microscopic (SEM) observations reveal good bioactivity of the HA‐Ti composites with the formation of thick, flaky, and porous apatite layer when immersed in simulated body fluid at 37°C and pH of 7.4. Atomic absorption spectroscopic analysis of the simulated body fluid solution reveals dynamic changes in Ca+2 ion concentration with more dissolution of Ca+2 ion from the HA‐20Ti composite. However, the measurements with inductively coupled plasma spectrometer do not record dissolution of Ti+4 ions. Transmission electron microscopic analysis indicates weak crystalline nature of the apatite and confirms the formation of fine‐scale apatite crystals. MTT assay, fluorescence, and SEM study demonstrate good cell viability and cell adhesion/proliferation of the Saos ‐2 cells, cultured on the developed composites under standard culture condition, and the difference in cell viability has been discussed in reference to substrate composition and roughness. Overall, HA‐Ti composites exhibit comparable and even better in vitro bioactivity and cytocompatibility properties than HA. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Biological activity of a nanofibrous barrier membrane containing bone morphogenetic protein formed by core‐shell electrospinning as a sustained delivery vehicle
Authors: Zhu Huiyong , Yu Dan , Zhou Ying , Wang Chi , Gao Mengfei , Jiang Hongliang , Wang Huiming
Published: December 2012

This study reports the in vitro and in vivo biological activities of recombinant human bone morphogenetic protein 2 (rhBMP‐2) released from the core‐shell structure of a nanofibrous barrier membrane as a sustained delivery model for bone regeneration. RhBMP‐2 incorporating poly(ethylene glycol) was used as the core, and poly(caprolactone) was used as the shell surrounding the core. To determine its release profiles, the release solution was collected and the amount of rhBMP‐2 was measured by ELlSA at different time points. In vitro rhBMP‐2, released from the delivery system over at least 24 days, reached a stable rate of 500 pg per day and guided bone marrow mesenchymal stem cells (BMMSCs) to express osteogenic genes. The distribution and proliferation of BMMSCs in the nanofibrous barrier membrane was measured by laser confocal scanning microscopy (LCSM) and scanning electron microscopy (SEM). The biological activity of rhBMP‐2 was tested in BMMSC/membrane culture in vitro and in a rabbit calvarium defect model in vivo. Osteogenic genes osteonectin (ON) and core binding factor‐α1 (Cbf‐α1) expression of the BMMSCs cultured on the BMP‐2‐PEG/PCL membrane were significantly higher than those of cells on the PEG/PCL membrane at the late time points using real‐time PCR (p < 0.05). The membranes containing the rhBMP‐2 group exhibited the fastest and most bone formation compared to others in rabbit cranial defect models (p < 0.05). This study revealed that rhBMP‐2 could be incorporated into a core‐shell electrospun membrane, and preserve sustained release capability and biological activity. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Physicochemical and cell biological characterization of PMMA bone cements modified with additives to increase bioactivity
Authors: Wolf‐Brandstetter Cornelia , Roessler Sophie , Storch Sandra , Hempel Ute , Gbureck Uwe , Nies Berthold , Bierbaum Susanne , Scharnweber Dieter
Published: December 2012

Polymethylmethacrylate (PMMA) bone cement is the most widely used material in surgery to fix joint replacements in the bone. In this study, we propose a new approach to generate bioactive PMMA surfaces directly at the site of implantation by adding the amphiphilic molecule phosphorylated 2‐hydroxyethylmethacrylate (HEMA‐P) to commercial PMMA bone cement, both with or without addition of 1–5% soluble calcium and carbonate salts. The setting behavior as well as the mechanical properties, the bonding quality at the metal/cement interface, mineral deposition, and cellular response for different cement modifications were investigated in vitro. The addition of HEMA‐P resulted in entirely positive effects with respect to proliferation and differentiation of osteoblast‐like cells (SaOs‐2) and a very tight contact at the metal/cement interface. No detrimental changes of other properties were detected. The additional incorporation of salts provoked an increased deposition of calcium phosphate minerals but no further improvement in SaOs‐2 cell differentiation. A significant decrease in polarization resistance for cements with high salt content (5%) was attributed to debonding between metal and cement. The results suggest an improved clinical performance of PMMA/HEMA‐P composites, which might be further enhanced by small amounts of the soluble salts. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Longitudinal study of vitamin D metabolites after long bone fracture
Authors: Briggs Adam DM , Kuan Valerie , Greiller Claire L , MacLaughlin Beverley D , Ramachandran Manoj , Harris Timothy , Timms Peter M , Venton Timothy R , Vieth Reinhold , Norman Anthony W , Griffiths Christopher J , Martineau Adrian R
Published: December 2012

Animal models suggest a key role for dihydroxylated vitamin D metabolites in fracture healing, as evidenced by increases in serum concentration of 24R,25-dihydroxyvitamin D (24R,25[OH]2D) after long bone fracture. Human studies investigating the kinetics of serum concentrations of 24R,25[OH]2D, 1,25-dihydroxyvitamin D (1,25[OH]2D) and their parent metabolite 25-hydroxyvitamin D (25[OH]D) are lacking. We, therefore, conducted a longitudinal study to determine whether total, free, or bioavailable concentrations of these vitamin D metabolites fluctuate in humans after long bone fracture. Twenty-eight patients with cross-shaft (diaphyseal) long bone fracture presenting to an emergency department in London, UK, were studied. Serum concentrations of 25(OH)D, 24R,25(OH)2D, 1,25(OH)2D, vitamin D binding protein, albumin, and calcium were determined within 48 hours of fracture and again at 1 and 6 weeks postfracture. Concentrations of free and bioavailable vitamin D metabolites were calculated using standard equations. No changes in mean serum concentrations of 25(OH)D or 24R,25(OH)2D were seen at either follow-up time point versus baseline. In contrast, mean serum 1,25(OH)2D concentration declined by 21% over the course of the study, from 68.5 pmol/L at baseline to 54.1 pmol/L at 6 weeks (p < 0.05). This decline was associated with an increase in mean serum corrected calcium concentration, from 2.32 mmol/L at baseline to 2.40 mmol/L at 1 week (p < 0.001) that was maintained at 6 weeks. No changes in free or bioavailable concentrations of any vitamin D metabolite investigated were seen over the course of the study. We conclude that serum 1,25(OH)2D concentration declines after long bone fracture in humans but that the serum 24R,25(OH)2D concentration does not fluctuate. The latter finding contrasts with those of animal models reporting increases in serum 24R,25(OH)2D concentration after long bone fracture.
Encouraging microbial activity in cementitious systems: an emerging frontier in contaminated soil treatment
Authors: Kogbara Reginald B.
Published: December 2012

Bioremediation is widely accepted as the most effective remediation technology for organic contamination. Nevertheless, it is ineffective for heavy metals, which cannot be degraded, and their immobilisation through pH control achieved with high‐pH cementitious materials is one of very few feasible means of treatment available. However, progress is being made in encouraging microbial activity in cementitious systems, which could provide a single technology that is effective and can be used for simultaneous treatment of organic and metallic contaminants in contaminated soils. This work considers efforts in this direction; the successes achieved and the challenges encountered are described. The utility of relatively low‐pH magnesium phosphate cement(s) and compost in providing a favourable environment for microbes, as well as the capacity of microbes like Saccharomyces cerevisiae and Rhodococcus ruber immobilised in the cement in degrading organics is highlighted. Overall, the findings are promising and are likely to expand the frontiers of bioremediation and stabilisation/solidification technologies for sustainable treatment of contaminated soils and may be extended to other applicable hazardous waste streams. © 2012 Society of Chemical Industry
Rapid start‐up of a sulfidogenic biofilm reactor: overcoming low acetate consumption
Authors: Celis Lourdes B. , Gallegos‐Garcia Marisol , Vidriales Guillermo , Razo‐Flores Elías
Published: December 2012

BACKGROUND

Sulfate‐reducing fluidized bed reactors represent an alternative for the treatment of wastewaters that contain dissolved metals. However, the low acetate consumption achieved through sulfate reduction affects the organic matter removal efficiency. The aim of this present work was to develop a sulfidogenic biofilm able to consume acetate via sulfate reduction within a short start‐up period (21 days). Three experiments were conducted in a down‐flow fluidized bed reactor with different acetate/lactate proportions in the feed (50/50, 80/20 and 90/10). Reduction of the influent pH from 6.0 to 4.0 was also studied at the higher acetate content.

RESULTS

Organic matter oxidation efficiency was similar in the three experiments (∼67%), nonetheless the sulfate reduction rate was higher in the experiments with 80 and 90% acetate in the feed (744 and 730 mg L−1 d−1). Acetate oxidation via sulfate reduction was highest (39% of inlet) at the ratio 90/10, at which the biofilm specific sulfate reducing activity with acetate was 4.3 times higher than that developed at 50/50. Influent pH reduction to 4.0 was not detrimental to acetate consumption via sulfate reduction, which was 56%. Analysis of the biofilm through DGGE found a similar community in the three experiments and the presence of acetotrophic microorganisms affiliated to Desulfobacca acetoxidans.

CONCLUSIONS

Limiting the substrate (lactate) was an appropriate strategy to enrich acetate‐consuming sulfate reducers and improve the low acetate removal efficiency that sulfate‐reducing reactors face. © 2012 Society of Chemical Industry
Combined linear array high‐ and convex array low‐frequency duplex ultrasonography with or without examination of the ophthalmic artery in the differential diagnosis of occlusion from severe stenosis of internal carotid artery
Authors: Xiong Jian‐Qun , Wang Li , Yu Chen , Shi Yu‐Wen , Li Ying‐Hua
Published: December 2012

Purpose

To assess the benefits of using a low‐frequency convex probe and detecting ophthalmic artery blood flow for the differential diagnosis of occlusion from severe stenosis of the internal carotid artery (ICA).

Methods

A total of 103 patients were enrolled and had three sequential examinations by an experienced sonographer. First, the proximal ICA was examined with a 5.0–7.5‐MHz linear probe. Second, the distal ICA was examined with a 3.5–5.0‐MHz convex probe. Third, the ophthalmic artery (OA) was examined with a 5.0–7.5‐MHz linear probe. Three parallel sets of diagnoses were made based on results from (1) high‐frequency ultrasonography; (2) combined use of high‐ and low‐frequency ultrasonography; and (3) combined use of high‐ and low‐frequency ultrasonography along with OAs examination findings. Efficiencies of the three diagnoses were compared by receiver operating characteristic curves with digital subtraction angiography as the gold standard.

Results

The second diagnostic approach yielded the highest sensitivity (96.6%) and specificity (94.5%). OA blood flow was reversed in most, but not all, cases of ICA occlusion (27/29). Areas under the receiver operating characteristic curves of the three diagnoses were significantly different (p < 0.05).

Conclusions

The diagnostic performance of combined high‐ and low‐frequency ultrasonography is greater than that of high‐frequency ultrasonography alone. Although OA examination does not increase the diagnostic performance, it provides helpful data for the assessment of hemodynamics and collateral circulation. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound 41:408–414, 2013
Myoanatomy of Myzostoma cirriferum (Annelida, Myzostomida): Implications for the evolution of the myzostomid body plan
Authors: Helm Conrad , Weigert Anne , Mayer Georg , Bleidorn Christoph
Published: December 2012

Studies of rare genomic marker systems suggest that Myzostomida are a subgroup of Annelida and phylogenomic analyses indicate an early divergence of this taxon within annelids. However, adult myzostomids show a highly specialized body plan, which lacks typical annelid features, such as external body annulation, coelomic cavities with metanephridia, and segmental ganglia of the nervous system. The putative loss of these features might be due to the parasitic/symbiotic lifestyle of myzostomids associated with echinoderms. In contrast, the larval anatomy and adult locomotory system resemble those of annelids. To clarify whether the myoanatomy of myzostomids reflects their relationship to annelids, we analyzed the distribution of f‐actin, a common component of muscle fibers, in specimens of Myzostoma cirriferum using phalloidin‐rhodamine labeling in conjunction with confocal laser‐scanning microscopy. Our data reveal that the musculature of the myzostomid body comprises an outer circular layer, an inner longitudinal layer, numerous dorsoventral muscles, and prominent muscles of the parapodial complex. These features correspond well with the common organization of the muscular system in Annelida. In contrast to other annelids, however, several elements of the muscular system in M. cirriferum, including the musculature of the body wall, and the parapodial flexor muscles, exhibit radial symmetry overlaying a bilateral body plan. These findings are in line with the annelid affinity of myzostomids and suggest that the apparent partial radial symmetry of M. cirriferum arose secondarily in this species. Based on our data, we provide a scenario on the rearrangements of muscle fibers that might have taken place in the lineage leading to this species. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.
Automated liver stiffness measurements with magnetic resonance elastography
Authors: Dzyubak Bogdan , Glaser Kevin , Yin Meng , Talwalkar Jayant , Chen Jun , Manduca Armando , Ehman Richard L.
Published: December 2012

Purpose

To provide a fully automated algorithm for obtaining stiffness measurements from hepatic magnetic resonance elastography (MRE) images that are consistent with measurements performed by expert readers.

Materials and Methods

An initial liver contour was found using an adaptive threshold and expanded using an active contour to select a homogeneous area of the liver. The confidence map generated during the stiffness calculation was used to select a region of reliable wave propagation. The average stiffness within the automatically generated region of interest (ROI) was compared to measurements by two trained readers in a set of 88 clinical test cases ranging from healthy to severely fibrotic.

Results

The stiffness measurements reported by the readers differed by −6.76% ± 22.8% (95% confidence) and had an intraclass correlation coefficient (ICC) of 0.972 (P < 0.05). The algorithm and the more experienced reader differed by 4.32% ± 14.9 with an ICC of 0.987.

Conclusion

The automated algorithm performed reliably, even though MRE acquisitions often have motion artifacts present. The correlation between the automated measurements and those from the trained readers was superior to the correlation between the readers. J. Magn. Reson. Imaging 2013;38:371–379. © 2013 Wiley Periodicals, Inc.
Detection of enterovirus in the thyroid tissue of patients with graves' disease
Authors: Hammerstad Sara Salehi , Tauriainen Sisko , Hyöty Heikki , Paulsen Trond , Norheim Ingrid , Dahl‐Jørgensen Knut
Published: December 2012

The etiology and pathogenesis of Graves' disease (GD) are still unknown, although it is thought that both genetic and environmental factors are important. Some indirect evidence implies that a viral infection may be a possible etiologic factor in autoimmunity. The main objective of this study was to examine direct evidence of the presence of enteroviruses (EVs) in the thyroid tissue of patients with GD. Thyroid tissue from 22 patients with newly diagnosed GD was obtained by core needle biopsy, while tissue from 24 patients with chronic GD and 24 control subjects without any autoimmune thyroid diseases was collected during neck surgery. Formalin‐fixed, paraffin‐embedded thyroid tissue samples were examined for the presence of enterovirus capsid protein using immunohistochemistry and for enterovirus RNA using in situ hybridization. Enterovirus capsid protein was detected in 17 (37%) patients and in 4 (17%) control subjects (P = 0.103). Enterovirus RNA was identified in thyroid tissue from nine (20%) patients, but in none of the control subjects (P = 0.016). Eight (90%) of the nine virus RNA positive patients were also positive for enterovirus protein. This is the first study to analyze thyroid tissue for EVs, including patients with untreated, newly diagnosed GD. The results suggest that EVs are more frequently present in thyroid tissue of patients than controls. Further studies are indicated to explore this association to find out if a low‐grade chronic enteroviral infection might be involved in the pathogenesis of GD and if this could offer new therapeutic and preventive opportunities. J. Med. Virol. 85:512–518, 2013. © 2012 Wiley Periodicals, Inc.
Innovation: Misconceptions, trends, and directions
Authors: Bel Roland
Published: December 2012

Close observation of innovative organizations ranging from 3M to Cirque du Soleil sheds light on common principles and philosophies that have spurred their groundbreaking development. To maintain a leading edge, companies must first dispense with a series of myths that have arisen around the topic of innovation. Contrary to popular belief, innovation is taking place in developing countries, and the most successful companies are followers rather than pioneers. Innovative companies know when to kill projects and learn how to exploit the sources of innovation more comprehensively and more efficiently, leveraging technology and ideas coming from universities, suppliers, competitors, users, other industries or customer segments, and employees. The most successful companies foster an innovation‐oriented culture, are customer‐oriented, and become masters of execution. In sum, innovation is a complex process that requires discipline and methodology. © 2013 Wiley Periodicals, Inc.
Moisture Permeation in Liquid Crystalline Epoxy Thermosets
Authors: Nie Lei , Burgess Andrew , Ryan Anthony
Published: December 2012

A liquid crystalline thermoset (LCT), 4,4′‐diglycidyloxy‐α‐methylstilbene/sulfanilamide, is studied by dynamic mechanical and vapor sorption measurements. Sub‐Tg transitions are assigned to the specific segmental motions through molecular modeling and used to define the environmental temperatures for the study of water transport properties in LCT. The variation of moisture transport with amine‐epoxy ratio reveals that the crosslink density and local concentration of polar groups play the key role in determining both the diffusivity and solubility. The LCT exhibits much lower water diffusion than analogous isotropic networks while the solubility is essentially the same. Segmental flexibility and an ordered smectic layered structure are responsible for the lower permeability.
Investigation of flax fibre reinforced epoxy friction composites
Authors: Taha I.
Published: December 2012

The use of eco‐materials on the basis of natural fibre reinforced polymer composites has found its way to many applications. In the automobile sector, the use of such composites has long been established for applications in the car interior. The use of natural fibre reinforced composites for braking applications has however not been confirmed yet. In this study the use of flax fibres as a candidate reinforcement substitution for glass or even the carcinogenic asbestos fibres has been investigated. Typical frictional materials such as alumina, iron and brass particulates have been used together with graphite as a lubricant. Epoxy resin was used as the binding matrix. Results show frictional behaviours comparable with commercially available brake linings at acceptable wear rates.
Environmental fatigue behavior of non‐crimp, E‐glass fiber reinforced polyester composites for marine applications
Authors: Altunsaray E. , Neser G. , Erbil C. , Gürsel K. T. , Ünsalan D.
Published: December 2012

This study is aimed to find the fatigue behavior of Glass Reinforced Plastics, a material which is a widely preferred material for small marine crafts, as well as several other applications. The type of composite tested is hand‐laid E‐glass non‐crimp reinforcements with an polyester resin matrix. The specimens were produced in two standard thicknesses and with these material directions and were tested both under atmospheric and simulated seawater environments for fatigue. It was seen that the results of fatigue lifetime obtained by testing the material in seawater is much lower than the results obtained from testing similar specimens under atmospheric conditions. However, the stress curves indicate the same slope, suggesting that the fatigue failure mechanism of both testing conditions is the same and the fiber‐related factors dominate. It was found that the thickness and material direction did not have a significant effect on the fatigue behavior of the material.
Slip‐rolling resistance of ta‐C and a‐C coatings up to 3,000 MPa of maximum Hertzian contact pressure
Authors: Woydt M. , Scholz C. , Manier C.‐A. , Brückner A. , Weihnacht V.
Published: December 2012

The slip‐rolling resistances of hard and stiff thin films under high Hertzian contact pressures can be improved by optimizing the “coating/substrate systems”. It is known from former investigations that the so‐called “egg‐shell” effect is no general hindrance for high slip‐rolling resistance of thin hard coatings. The coating stability depends more on specific deposition process and coating/substrate interface design. In this article it is experimentally shown, that pure amorphous carbon thin films with hardness between 15 and 63 GPa can be slip‐rolling resistant several million load cycles under a maximum Hertzian contact pressures of up to 3.0 GPa. Whereas all coatings were stable up to 10 million load cycles in paraffin oil at room temperature, reduced coating lifetime was found in SAE 0W‐30 engine oil at 120°C. It was shown how the coating hardness and the initial coating surface roughness influence the running‐in process and coating lifetime. No clear correlation between coating hardness and coating lifetime could be observed, but friction coefficients seem to be reduced with higher coating hardness. Very low friction down to ˜0.03 in unmodified engine oils was found for the hardest ta‐C film.
Plural Forms of Organization: Where Do We Stand?
Authors: Ménard Claude
Published: December 2012

This paper addresses a puzzling problem: why do parties often choose to combine alternative modes of organizations simultaneously while dealing with identical or almost identical transactions? I propose a model to capture these so‐called ‘plural forms’ and to explain the choice of such non‐standard arrangements. Three determinants are identified as playing the major role: ambiguity surrounding the fitness of a mode of organization to the transaction at stake; complexity of a transaction or a set of transactions; and strategic behavior. Propositions are derived that are confronted to empirical data coming out of the agro‐food industry. Copyright © 2012 John Wiley & Sons, Ltd.
Network Integration Through Franchised and Company‐Owned Chains: Evidence from French Distribution Networks
Authors: Chaudey Magali , Fadairo Muriel , Solard Gwennaël
Published: December 2012

To the best of our knowledge, no previous studies have examined the degree of vertical integration by comparing franchised and company‐owned chains. On the basis of recent data from the French distribution networks in retail and services, this paper investigates the determinants of network integration in the French distribution systems. The level of network integration increases from franchised chains to company‐owned chains. This paper provides evidence that the level of network integration is positively related to the brand name value and negatively related to the resource constraints and monitoring costs of the upstream firm. Copyright © 2012 John Wiley & Sons, Ltd.
A Two‐Stage Double Bootstrap DEA: The Case of the Top 25 European Football Clubs' Efficiency Levels
Authors: Halkos George E. , Tzeremes Nickolaos G.
Published: December 2012

This paper analyzes how European football clubs' current value and debt levels influence their performance. The Simar and Wilson (J Econometrics, 136: 31–64, 2007) procedure is used to bootstrap the data envelopment analysis scores in order to establish the effect of football clubs' current value and debt levels on their obtained efficiency scores. The results reveal that football clubs' current value levels have a negative influence on their performances, indicating that football clubs' high value does not ensure higher performance. At the same time, the empirical evidence suggests that football clubs' debt levels do not influence their efficiency levels. Copyright © 2012 John Wiley & Sons, Ltd.
Use of volterra‐series in optimizing harmonic load impedance for suppressing IM3 in LTE InGaP HBT power amplifiers
Authors: Zhang Xiaodong , Gao Huai , Li G.P.
Published: December 2012

The nonlinear distortion in InGaP/GaAs HBT power amplifiers for long‐term evolution applications is analyzed using Volterra series. The interdependence between third‐order intermodulation (IM3) and harmonic load impedance suggests an alternative technique to improve PAs' linearity. The measurement results show that IM3 is suppressed by more than 6 dB, whereas other performances are not affected. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:341–344, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27286
Planar UWB monopole antenna with dual band‐notched characteristics for UWB applications
Authors: Yazdi Mohammad , Komjani Nader
Published: December 2012

A simple and compact circular ultra‐wideband (UWB) planar monopole antenna with dual band‐notched characteristics is presented. By inserting a pair of two slots in the ground plane as well as adding a pair of arc‐shaped parasitic strips around the radiating element, two notched frequency bands in the WiMAX/WLAN are achieved. Experimental results show a VSWR<2 bandwidth of 7.6 GHz for nondefected antenna and two highly rejected bands in the frequency region of 3.3–3.7GHz and 5–6GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:241–245, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27301
High linearity microstrip bandpass filter with electronically tunable notch
Authors: Rabbi K. , Athukorala L. , Budimir D.
Published: December 2012

A high linearity reconfigurable bandpass filter embedded with a tunable notch structure has been presented for future wideband wireless communication applications. A single varactor diode (BB135‐NXP) is used for the purpose of tuning the notch. The linearity of the varactor‐tuned bandpass filter is also evaluated. The proposed filter is able to achieve a good linearity with IIP3 of 37, 46, and 45 dB at 2.3, 2.4, and 2.5 GHz, respectively, and with no significant loss. Simulations have been verified by the measurements of a fabricated prototype. A good agreement has been achieved simulated and measured results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:418–421, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27312
A compact tapered slot antenna for ultrawideband applications
Authors: Yan Zhong‐Min , Xu Yun‐Sheng , Wang Wei‐Dong
Published: December 2012

An elliptically tapered slot antenna fed by a tapered microstrip line ended with a sector‐shaped tuning stub for ultrawideband operations is presented. The antenna is printed on a circuit board with a low relative dielectric constant of 2.65. A T‐shaped shorting strip is used to improve directional radiation performance. The antenna achieves a measured impedance bandwidth from 3.25 to 12 GHz with the gain in the end‐fire direction up to 5.5 dB and a compact size of 27 × 40 × 0.5 mm3. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:295–299, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27319
Breath sensor based on reflective optical lensed fiber
Authors: Lin Yu‐Cheng
Published: December 2012

An optical lensed fiber for detecting respiration condition in the vicinity of nose has been proposed and been demonstrated to work as a breath sensor. For simple preparation and larger sensing area, a piece of about quarter‐pitch of an optical gradient index fiber (GIF) tip was spliced to the end of a single mode fiber. The sensing principle is based on the change of back reflection intensity caused by attachment of water molecules on the GIF tip during respiration. The experimental results showed that this breath sensor operated with a good sensitivity and a real‐time respiration monitor was presented. In terms of the tiny size and light weight, the optical lensed fiber breath sensor is potential for the application of monitoring breathing condition in hospital and in home care. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:450–454, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27322
Analytical contribution of NAD 2D‐NMR spectroscopy in polypeptide mesophases to the investigation of triglycerides
Authors: Lesot Philippe , Serhan Zeinab , Aroulanda Christie , Billault Isabelle
Published: December 2012

In this work, we report and discuss on the use and limitations of the natural abundance deuterium two‐dimensional NMR spectroscopy in polypeptide chiral and achiral aligning media in the studies of homogenous triglycerides at 14.1 T. As illustrative examples, two triglycerides with short and long alkyl chains were investigated: the 1,3‐di(butanoyloxy)propan‐2‐yl butanoate or tributyrin (TB) and the 1,3‐di(tetradecanoyloxy)propan‐2‐yl tetradecanoate or trimyristin (TM). If both flexible compounds are theoretically of Cs symmetry on average, according to the Altmann's definition (Proc. Roy. Soc., 1967, A298, 184.), the analysis of spectral data in terms of enantiotopic and diastereotopic discriminations shows noticeable differences related to their orientational ordering behavior inside the mesophases. Although from NMR analysis viewpoint, TB behaves as a Cs symmetry molecule as expected, the NMR results obtained for TM suggest a behavior that could be formally predicted for a C3v symmetry molecule on average. This conclusion was nicely supported by the comparison with the tri‐n‐propylorthoformate, a real C3v symmetry solute on average on the NMR timescale. This difference of effective orientational behavior could originate from the difference of size and shape between lateral and central alkyl chains of the solute molecule. Copyright © 2012 John Wiley & Sons, Ltd.
Total and selective reuse of Krylov subspaces for the resolution of sequences of nonlinear structural problems
Authors: Gosselet P. , Rey C. , Pebrel J.
Published: December 2012

This paper deals with the definition and optimization of augmentation spaces for faster convergence of the conjugate gradient method in the resolution of sequences of linear systems. Using advanced convergence results from the literature, we present a procedure on the basis of a selection of relevant approximations of the eigenspaces for extracting, selecting and reusing information from the Krylov subspaces generated by previous solutions in order to accelerate the current iteration. Assessments of the method are proposed in the cases of both linear and nonlinear structural problems. Copyright © 2012 John Wiley & Sons, Ltd.
Cause‐related marketing and customer donations in an online marketplace
Authors: Aldridge Nick , Fowles Joe
Published: December 2012

eBay for Charity provides mechanisms for embedding charitable fundraising and donations into the UK's largest online marketplace, with 18 million unique visitors each month. This paper explores some of our findings concerning the impact of charitable activity on the behaviour of those who participate, including buyers, sellers, and the charities themselves, and suggests ways these findings could be applied to other forms of online fundraising in the future.

Copyright © 2012 John Wiley & Sons, Ltd.
Clinical application of midtrimester non‐invasive fetal RHD genotyping and identification of RHD variants in a mixed‐ethnic population
Authors: Grande M. , Ordoñez E. , Cirigliano V. , Cid J. , Grau E. , Pericot A. , Teixido I. , Marin J. L. , Borrell A.
Published: December 2012

Objective

This study aims to assess the suitability of non‐invasive prenatal RHD genotyping in non‐immunized midtrimester pregnant women from a mixed ethnic population, to prevent unnecessary anti‐D immunoglobulin prophylaxis and to identify RHD variants

Methods

Rhesus D‐negative pregnant women were offered fetal RHD genotyping at 24 gestational weeks. A total of 284 samples were tested for RHD status using multiplex rt‐PCR amplification of exons 5 and 7 of the RHD gene and exons 6 and 10 in selected cases. Women carrying RHD‐negative fetuses were counseled about their option to avoid routine antenatal anti‐D immunoglobulin administration. Diagnostic accuracy of RHD genotyping was compared with postnatal Rhesus D serotyping.

Results

A total of 184 positives (65%), 91 negatives (32%) and 7 cases (2.5%) compatibles with RHD variants were detected by RHD genotyping. No false negative results were found, and a single false positive was observed in a twin pregnancy. Genotyping was accepted when offered by 94% of women (284/302), and anti‐D immunoglobulin was avoided in 95% (90/95) of RHD‐negative fetuses.

Conclusions

Non‐invasive routine antenatal RHD genotyping at 24 weeks of pregnancy is a highly accurate method, resulting in the avoidance of 95% of unnecessary administrations of anti‐D immunoglobulin, with no false negative results. © 2012 John Wiley & Sons, Ltd.
Injection molding electroluminescent components
Authors: Middleton B. , Goodship V.
Published: December 2012

This article explores the feasibility of using mass manufacture, namely injection molding, as a route to produce cost effective electroluminescent (EL) components straight from the mold tool. EL screen printing pastes were adapted and introduced into the injection molding environment as a multilayer structure. Four‐layer systems were investigated using a spray deposition method to apply individual layer components directly in‐mold. Finally, the substrate was back injected to produce a three‐dimensional illuminating device straight from the mold tool. Materials, methods, and outcomes are described, the implication being that electronic manufacture could be moved upstream and performed in‐mold with resultant cost and energy savings. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Fatigue crack growth behavior and mechanism of closed‐cell PVC foam
Authors: Poapongsakorn P. , Kanchanomai C.
Published: December 2012

The applicability of linear‐elastic fracture mechanics parameters (ΔK and Kmax), elastic–plastic fracture mechanics parameter (ΔJ), and time‐dependent fracture mechanics parameter (C*) to characterize fatigue crack growth (FCG) rate of closed‐cell polyvinyl chloride foam was investigated in the present work. The effect of stress ratios (R = 0.1 and 0.4) on FCGs was observed when the ΔK, Kmax and ΔJ were used as fracture mechanics parameters. As a fracture mechanics parameter that combines ΔK and Kmax, the K* successfully characterized FCGs (da/dN) at R = 0.1 and 0.4. While, a time‐dependent fracture mechanics parameter (C*) successfully correlated da/dt of creep crack growth (CCG) test, but it failed to correlate da/dt of FCG tests. The FCGs at both R = 0.1 and 0.4 were cyclic dependent, while the CCG was time dependent. For cyclic‐dependent crack growth, the interaction between polymer‐chain scission and small scale crack‐tip blunting was the main mechanism, whereas the interaction between polymer‐chain pullout and large scale crack‐tip blunting dominated fracture process for time‐dependent crack growth. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Dielectric analysis of α‐relaxation process of chlorinated poly(vinyl chloride) stabilized with nitro‐phenyl maleimide
Authors: Hanafy Taha Abdel‐Maguid , Mahrous Salah
Published: December 2012

Nitro‐phenyl maleimide (NPM), is the organic stabilizer for poly (vinyl chloride) (PVC), has been investigated as thermal plasticization for rigid chlorinated poly (vinyl chloride) (CPVC). Dielectric relaxation of CPVC stabilized with 10 wt% of NPM has been studied in temperature and frequency ranges of 300–450 K and 10 kHz–1 MHz, respectively. An analysis of the dielectric constant, ε′ and dielectric loss index, ε″, was performed assuming a plasticization effect of NPM molecules. The plasticization effect of NPM molecules was confirmed by the behavior of the dielectric modulus M′ and M″ spectra. A clear dielectric α‐relaxation process has been obtained in the studied temperature range. The results showed that NPM reduce the glass transition temperature, Tg, of CPVC by about 20 K. This effect has been assigned to the plasticization effect of NPM. At lower temperatures, dielectric modulus spectra reveal that there is a role of the effect of the electrode polarization in the relaxation process. The behavior AC conductivity, σac, indicated that the conduction mechanism in all CPVC samples is hopping type conduction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Surface photovoltage spectroscopy on Cu(In,Ga)(S,Se)2/ZnS‐nanodot/In2S3 systems
Authors: Fu Yanpeng , Rada Tomàs , Fischer Christian‐Herbert , Lux‐Steiner Martha Ch. , Dittrich Thomas
Published: December 2012

Single layers and combined layer systems with Cu(In,Ga)(S,Se)2, ZnS‐nanodot (nd) and In2S3 layers were investigated by surface photovoltage spectroscopy in the Kelvin‐probe arrangement and compared with the open‐circuit voltage (VOC) of solar cells. The In2S3 and ZnS‐nd layers were prepared by the spray ion layer gas reaction (ILGAR) technique from Indium chloride (InCl3), Indium acetylacetonate (In(acac)3) and Zinc acetylacetonate, respectively. The surface photovoltage signals of Cu(In,Ga)(S,Se)2 were larger for the Cu(In,Ga)(S,Se)2/ZnS‐nd/In2S3 than for the Cu(In,Ga)(S,Se)2/In2S3 layer system showing that a ZnS‐nd layer additionally passivated the Cu(In,Ga)(S,Se)2 surface. ILGAR In2S3 deposition from InCl3 precursor solution led to a modification of surface defects of ZnS‐nd and to generation of defect states below the band gap of Cu(In,Ga)(S,Se)2, which has not been observed for deposition from Indium acetylacetonate precursor. Defect generation during ILGAR In2S3 deposition with InCl3 precursor resulted in a lower VOC of Cu(In,Ga)(S,Se)2/ZnS‐nd/In2S3/ZnO : Al solar cells. Copyright © 2012 John Wiley & Sons, Ltd.
Effective surface passivation of Si surfaces by chemical deposition of (Al2O3)x(B2O3)1 − x thin layers
Authors: Vitanov Petko , Harizanova Antoaneta , Ivanova Tatyana , Perego Michele , Stokkan Gaute , Ulyashin Alexander
Published: December 2012

In this work chemical liquid deposition from sol–gel solutions has been used to obtain thin (Al2O3)x(B2O3)1 − x dielectric films. Passivation of Si surfaces using these films has been studied. Morphological properties of thin films deposited on polished Si surfaces have been investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) technique. Their chemical composition, structural and optical features have been analysed by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and ultraviolet‐visible (UV–VIS) spectroscopy. Results, obtained in this work, show that silicon surfaces can be effectively passivated by thin dielectric layers deposited from chemical solutions. The thin dielectric layers developed in his work, can be recommended as back side passivation coating for Si‐based solar cells.
Continuous wave OSL in bulk AlN single crystals
Authors: Vokhmintsev Alexander , Weinstein Ilya , Spiridonov Dmitriy
Published: December 2012

The kinetics of recombination luminescence of β‐irradiated AlN single crystals has been studied with continuous wave optically stimulated luminescence (CW‐OSL) method. It is shown that the OSL process is characterized by two exponential components with a decay time τ = 32 and 212 s. Photoionization cross‐sections σ = 4.8·10‐19 and 7.3·10‐20 cm2 have been evaluated, assuming each component is related to electron traps based on VN‐ and/or ON‐centers at various charged states. It is established that dose dependences of the OSL response of the bulk crystals under study are linear with taking into correct accounting for the radiation induced afterglow and hence can be used for quantitative estimates in solid state dosimetry. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stress distribution of 12 μm thick crack free continuous GaN on patterned Si(110) substrate
Authors: Hossain T. , Wang J. , Frayssinet E. , Chenot S. , Leroux M. , Damilano B. , Demangeot F. , Durand L. , Ponchet A. , Rashid M. J. , Semond F. , Cordier Y.
Published: December 2012

The stress distribution on crack free thick continuous GaN film (12 µm) grown by Metal organic chemical vapour deposition (MOCVD) on the arrays of different sizes of the patterned silicon substrate is investigated by micro‐Raman (µRaman) spectroscopy. On the largest crack free mesa (400 μm) both µ‐photoluminescence (µPL) at low temperature and µRaman measurements are performed. The µRaman shift of the GaN E2 mode shows the U‐shape in‐plane stress distribution across the mesa. The center of the mesa is under tensile stress and it relaxes near the corner and edges. A similar trend is observed also from the µPL spectra. The size of the mesa, the trench height and the trench width of the patterned silicon are varied to study the stress of the thick epitaxial crack free GaN layer. The size and trench height of the mesa have a large influence on the GaN film stress but the trench width does not show any significant effect. The maximum stress is saturated for the large sizes of mesas. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterisation of III‐nitride materials by synchrotron X‐ray microdiffraction reciprocal space mapping
Authors: Kachkanov Vyacheslav , Dolbnya Igor , O'Donnell Kevin , Lorenz Katharina , Pereira Sergio , Watson Ian , Sadler Thomas , Li Haoning , Zubialevich Vitaly , Parbrook Peter
Published: December 2012

X‐ray Reciprocal Space Mapping (RSM) is a powerful tool to explore the structure of semiconductor materials. However, conventional lab‐based RSMs are usually measured in two dimensions (2D) ignoring the third dimension of diffraction‐space volume. We report the use of a combination of X‐ray microfocusing and state‐of‐the‐art 2D area detectors to study the full volume of diffraction–space while probing III‐nitride materials on the microscale. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
EPR and ODMR defect control in AlN bulk crystals
Authors: Soltamov V. A. , Ilyin I. V. , Gurin A. S. , Tolmachev D. O. , Romanov N. G. , Mokhov E. N. , Mamin G. V. , Orlinskii S. B. , Baranov P. G.
Published: December 2012

The results of pulse electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR) and optically detected magnetic resonance (ODMR) are presented to show the electron structure of deep level defect color center in AlN single crystals such as a nitrogen vacancy in neutral charge state (VN0) as well as a new type of point defect such as exchange–coupled pair of the nitrogen vacancies (VN‐VN). Analyzing spin density distribution of an unpaired VN0 electron on different ions of AlN crystalline lattice by means of high frequency ENDOR technique (94 GHz) give us a possibility to calculate hyperfine and quadrupole interactions (QI) with 27Al nuclei spins up to fourth coordinate sphere. Particularly data about quadrupole interactions allowed to estimate the fundamental parameter of AlN crystalline lattice in itself namely so called «crystalline field gradient» to be 4.9×1020V/m2 (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)