bluuebunny/crossref_metadata_2025 huggingface dataset:
Petrology‐based modeling of mantle melt electrical conductivity and joint interpretation of electromagnetic and seismic results
Authors: Pommier A. , Garnero E. J.
Published: April 2014

The presence of melt in the Earth's interior depends on the thermal state, bulk chemistry, and dynamics. Therefore, the investigation of the physical and chemical properties of melt is a probe of the planet's structure, dynamics, and potentially evolution. Here we explore melt properties by interpreting geophysical data sets sensitive to the presence of melt (electromagnetic and seismic) with considerations of petrology and, in particular, peridotite partial melting. We present a petrology‐based model of the electrical conductivity of fertile and depleted peridotites during partial melting. Seismic and magnetotelluric (MT) studies do not necessarily agree on melt fraction estimates, a possible explanation being the assumptions made about melt chemistry as part of MT data interpretation. Melt fraction estimates from electrical anomalies usually assume a basaltic melt phase, whereas petrological knowledge suggests that the first liquids produced have a different chemistry, and thus a different conductivity. Our results show that melts produced by low‐degree peridotite melting (< 15 vol %) are up to 5 times more conductive than basaltic liquids. Such conductive melts significantly affect bulk rock conductivity. Application of our electrical model to magnetotelluric results suggests melt fractions that are in good agreement with seismic estimates. With the aim of a simultaneous interpretation of electrical and seismic data, we combine our electrical results with seismic velocity considerations in a joint model of partial melting. Field electrical and seismic anomalies can be explained by ~1 vol % melt beneath Hawaii and ~1–8 vol % melt beneath the Afar Ridge.
On the distribution of CO2 and CO in the mesosphere and lower thermosphere
Authors: Garcia Rolando R. , López‐Puertas Manuel , Funke Bernd , Marsh Daniel R. , Kinnison Douglas E. , Smith Anne K. , González‐Galindo Francisco
Published: April 2014

We have used the Whole Atmosphere Community Climate Model (WACCM) to calculate the distribution of CO2 and CO in the mesosphere and lower thermosphere (MLT), and we have compared the results with observations, mainly from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer and Michelson Interferometer for Passive Atmospheric Sounding satellite‐borne instruments. We find that WACCM can reproduce the observed distribution of CO2 in the MLT and the rapid falloff of CO2 above about 80 km. Analysis of the principal terms in the calculated budget of CO2 shows that its global‐mean vertical profile is determined mainly by the competition between molecular diffusive separation and eddy mixing by gravity waves. The model underestimates somewhat the mixing ratio of CO2 in the thermosphere compared to that in the observations, but we show that the discrepancy may be eliminated by a reasonable adjustment of the Prandtl number used to calculate the diffusivity due to gravity waves. Simulated CO is also consistent with observations, except that in the standard version of the model, its mixing ratio is uniformly lower than observed above about 100 km. We conclude that WACCM likely underestimates the rate of production of CO in the lower thermosphere from photolysis of CO2 at wavelengths < 121 nm, and we show that this stems from the use of a very large absorption cross section for O2 in the wavelength range 105–121 nm. When a smaller cross section is used, photolysis of CO2 increases by a factor of 2–3 at ~ 95–115 km and, as a result, CO mixing ratios become larger and agree much more closely with observations. We emphasize that the increase in CO2 photolysis implies only minor changes in the vertical profile of CO2 because photolytic loss is a minor term in the budget of CO2 in the MLT.
Effects of crop residue burning on aerosol properties, plume characteristics, and long‐range transport over northern India
Authors: Kaskaoutis D. G. , Kumar S. , Sharma D. , Singh R. P. , Kharol S. K. , Sharma M. , Singh A. K. , Singh S. , Singh Atinderpal , Singh D.
Published: April 2014

Aerosol emissions from biomass burning are of specific interest over the globe due to their strong radiative impacts and climate implications. The present study examines the impact of paddy crop residue burning over northern India during the postmonsoon (October–November) season of 2012 on modification of aerosol properties, as well as the long‐range transport of smoke plumes, altitude characteristics, and affected areas via the synergy of ground‐based measurements and satellite observations. During this period, Moderate Resolution Imaging Spectroradiometer (MODIS) images show a thick smoke/hazy aerosol layer below 2–2.5 km in the atmosphere covering nearly the whole Indo‐Gangetic Plains (IGP). The air mass trajectories originating from the biomass‐burning source region over Punjab at 500 m reveal a potential aerosol transport pathway along the Ganges valley from west to east, resulting in a strong aerosol optical depth (AOD) gradient. Sometimes, depending upon the wind direction and meteorological conditions, the plumes also influence central India, the Arabian Sea, and the Bay of Bengal, thus contributing to Asian pollution outflow. The increased number of fire counts (Terra and Aqua MODIS data) is associated with severe aerosol‐laden atmospheres (AOD500 nm > 1.0) over six IGP locations, high values of Ångström exponent (>1.2), high particulate mass 2.5 (PM2.5) concentrations (>100–150 µgm−3), and enhanced Ozone Monitoring Instrument Aerosol Index gradient (~2.5) and NO2 concentrations (~6 × 1015 mol/cm2), indicating the dominance of smoke aerosols from agricultural crop residue burning. The aerosol size distribution is shifted toward the fine‐mode fraction, also exhibiting an increase in the radius of fine aerosols due to coagulation processes in a highly turbid environment. The spectral variation of the single‐scattering albedo reveals enhanced dominance of moderately absorbing aerosols, while the aerosol properties, modification, and mixing atmospheric processes differentiate along the IGP sites depending on the distance from the aerosol source, urban influence, and local characteristics.
Low‐altitude summer/winter microphysics, dynamics, and CCN spectra of northeastern Caribbean small cumuli, and comparisons with stratus
Authors: Hudson James G. , Noble Stephen
Published: April 2014

Low‐altitude cloud microphysics and cloud condensation nuclei (CCN) spectra are presented and analyzed from two cumulus cloud aircraft field campaigns, Ice in Clouds Experiment‐Tropical (ICE‐T) and Rain in Cumulus over the Ocean (RICO), in the same eastern Caribbean location at opposite seasons. These are further compared with two previously analyzed stratus cloud aircraft campaigns off the central California coast, Physics of Stratocumulus Tops (POST) and Marine Stratus/Stratocumulus Experiment (MASE). Multiple regression analysis predictions of cloud droplet concentrations (Nc) based on CCN spectra, NCCN(S) where S is supersaturation, compared much better with measured Nc than single NCCN‐Nc regressions in both cumulus projects. The addition of vertical velocity (W) to the single and multiple regressions showed small improvements. For RICO the multiple regression correlations were also superior to previous adiabatic model predictions of Nc also based on NCCN(S) and mean W. More adiabatic cloud parcels with considerably higher Nc, liquid water contents, and W showed only slightly better correlations than flight‐averaged Nc of all low clouds. Results show the value of more extensive CCN spectra and the relative unimportance of W variations for determining Nc, in these Caribbean cumuli. The fact that flight‐averaged Nc of all low cloud data was almost as well correlated with NCCN(S) as were Nc of more adiabatic cloud parcels indicates that entrainment did not significantly perturb CCN‐Nc relationships. As should be expected higher cloud S were determined for the cumulus clouds than for the stratus clouds. Suppression of cloud S by higher NCCN that had previously been observed in stratus was observed in ICE‐T but not in RICO where the NCCN range may have been too low for cloud S suppression. But ICE‐T and POST even showed this S suppression over the same limited NCCN range as RICO (< 200 cm−3).
On the possible interaction between internal climate variability and forced climate change
Authors: Lu Jianhua , Hu Aixue , Zeng Zhen
Published: April 2014

The global warming hiatus does not necessarily mean a hiatus in anthropogenic greenhouse gas forcing and forced climate change (FCC). Here we show that both Atlantic Multidecadal Variability (AMV) and Pacific Decadal Oscillation (PDO) may cause fluctuations of the global mean surface air temperature (SAT) and hence alternately positive and negative trends on (inter)decadal time scales. However, the forced SAT change under a mean state due to greenhouse gas forcing does not depend on different phases of AMV and PDO, implying the effect of the FCC and internally generated climate variability can be linearly added up to the observed transient global mean SAT. On the other hand, the regional patterns of transient FCC do depend on the phases of the internal variability since the atmospheric and oceanic circulations can be affected by the different phases of the internal variability. Our results suggest a two‐way interaction between internal variability and spatial patterns of FCC.
Piezoresistive Properties of Ag/Silica Nano‐Composite Thin Films Close to the Percolation Threshold
Authors: Gupta T. Das , Gacoin T. , Rowe A. C. H.
Published: April 2014

The effect of mechanical stress on the electrical properties of Ag/silica nano‐composite sol–gel films, fabricated using an ultra‐violet (UV) photo‐reduction process, is studied over a large range of Ag volume fractions, φ. The ability to finely tune φ in situ by varying the UV exposure time enables the direct identification of the critical volume fraction, φ* ≈ 13.1%, around which the resistance changes by 6 orders of magnitude and the average piezoresistive gage factor, , peaks at 4330.  is orders of magnitude larger than that of bulk silicon and φ* is close to the value expected for percolation in 3 dimensions. It is shown experimentally that this giant piezoresistance is the result of a stress‐induced change in the average Ag cluster size that significantly modifies the sample resistance when φ ∼ φ*. In terms of the potential use of any composite material as a sensitive strain sensor, a sensor figure‐of‐merit (F) that accounts for both  and for the measured, expected divergence in resistance fluctuations close to φ* is defined. It is shown that maximum F is achieved in composites slightly to the metallic side of the percolation transition. In the case studied here, the maximum value of F, which is 5–10 times larger than that measured on commercial strain gages under the same conditions, is obtained for φ ≈ 13.4%. The ability to finely tune φ in‐situ therefore suggests that Ag/silica nano‐composites could be the basis for a highly sensitive, low power, strain sensing technology.
Wearable and Highly Sensitive Graphene Strain Sensors for Human Motion Monitoring
Authors: Wang Yan , Wang Li , Yang Tingting , Li Xiao , Zang Xiaobei , Zhu Miao , Wang Kunlin , Wu Dehai , Zhu Hongwei
Published: April 2014

Sensing strain of soft materials in small scale has attracted increasing attention. In this work, graphene woven fabrics (GWFs) are explored for highly sensitive sensing. A flexible and wearable strain sensor is assembled by adhering the GWFs on polymer and medical tape composite film. The sensor exhibits the following features: ultra‐light, relatively good sensitivity, high reversibility, superior physical robustness, easy fabrication, ease to follow human skin deformation, and so on. Some weak human motions are chosen to test the notable resistance change, including hand clenching, phonation, expression change, blink, breath, and pulse. Because of the distinctive features of high sensitivity and reversible extensibility, the GWFs based piezoresistive sensors have wide potential applications in fields of the displays, robotics, fatigue detection, body monitoring, and so forth.
Photoinduced Anisotropic Supramolecular Assembly and Enhanced Charge Transport of Poly(3‐hexylthiophene) Thin Films
Authors: Chang Mincheol , Lee Jiho , Kleinhenz Nabil , Fu Boyi , Reichmanis Elsa
Published: April 2014

The self‐organization of organic polymer semiconductors into ordered supramolecular assemblies commensurate with efficient charge transport is achieved by tuning a range of process parameters (e.g., film deposition method (spin vs drop cast), solvent boiling point (low vs high boiling point), polymer‐dielectric interface treatment, and post‐deposition processing (solvent vapor or thermal annealing)). However, these strategies present limitations for large‐scale high‐throughput processing due to associated pre‐ and/or post semiconductor deposition steps. Here, photoinduced anisotropic supramolecular assembly of P3HT chains in solution is demonstrated. UV irradiation provides for enhanced intramolecular ordering of solubilized polymer chains, and thereby effects formation of anisotropic supramolecular polymer assemblies via favorable π–π stacking (intermolecular interaction). Molecular ordering is thus dramatically enhanced with concomitant, enhanced charge transport characteristics of corresponding films. Additional pre‐ and/or post treatments are avoided.
Cryogel Micromechanics Unraveled by Atomic Force Microscopy‐Based Nanoindentation
Authors: Welzel Petra B. , Friedrichs Jens , Grimmer Milauscha , Vogler Steffen , Freudenberg Uwe , Werner Carsten
Published: April 2014

Cell‐instructive physical characteristics of macroporous scaffolds, developed for tissue engineering applications, often remain difficult to assess. Here, an atomic force microscopy‐based nanoindentation approach is adapted to quantify the local mechanical properties of biohybrid glycosaminoglycan–poly(ethylene glycol) cryogels. Resulting from cryoconcentration effects upon gel formation, cryogel struts are observed to feature a higher stiffness compared to the corresponding bulk hydrogel materials. Local Young's moduli, porosity, and integral moduli of the cryogel scaffolds are compared in dependence on gel formation parameters. The results provide valuable insights into the cryogelation process and a base for adjusting physical characteristics of the obtained cryogel scaffolds, which can critically influence the cellular response.
Lessons Learned: From Dye‐Sensitized Solar Cells to All‐Solid‐State Hybrid Devices
Authors: Docampo Pablo , Guldin Stefan , Leijtens Tomas , Noel Nakita K. , Steiner Ullrich , Snaith Henry J.
Published: April 2014

The field of solution‐processed photovoltaic cells is currently in its second spring. The dye‐sensitized solar cell is a widely studied and longstanding candidate for future energy generation. Recently, inorganic absorber‐based devices have reached new record efficiencies, with the benefits of all‐solid‐state devices. In this rapidly changing environment, this review sheds light on recent developments in all‐solid‐state solar cells in terms of electrode architecture, alternative sensitizers, and hole‐transporting materials. These concepts are of general applicability to many next‐generation device platforms.
Microscale Motion Control through Ferromagnetic Films
Authors: Benassi Andrea , Schwenk Johannes , Marioni Miguel A. , Hug Hans J. , Passerone Daniele
Published: April 2014

Actuation and control of motion in micromechanical systems are technological challenges, since they are accompanied by mechanical friction and wear, principal and well‐known sources of device lifetime reduction. In this theoretical work we propose a non‐contact motion control technique based on the introduction of a tunable magnetic interaction. The latter is realized by coating two non‐touching sliding bodies with ferromagnetic films. The resulting dynamics is determined by shape, size and ordering of magnetic domains arising in the films below the Curie temperature. We demonstrate that the domain behavior can be tailored by acting on handles like ferromagnetic coating preparation, external magnetic fields and the finite distance between the plates. In this way, motion control can be achieved without mechanical contact. Moreover, we discuss how such handles can disclose a variety of sliding regimes. Finally, we propose how to practically implement the proposed model sliding system.
Surface Modification of Diamond‐Like Carbon Film with Polymer Brushes Using a Bio‐Inspired Catechol Anchor for Excellent Biological Lubrication
Authors: Wei Qiangbing , Pei Xiaowei , Hao Junying , Cai Meirong , Zhou Feng , Liu Weimin
Published: April 2014

Diamond‐like carbon (DLC) film has emerged as a promising material for biomedical applications, but its low tribological properties in air could not be adapted in water and biological fluids. Herein, mussel‐inspired catechol adhesive is presented to functionalize DLC film and then polymer brushes are grafted by surface initiated atom transfer radical polymerization (SI‐ATRP) to mimic excellent biological lubrication of articular cartilage. Macroscopic tribological evaluation demonstrates low and stable friction coefficient of polymer brushe modified DLC film in water and biological fluids when sliding with a soft polydimethylsiloxane (PDMS) hemisphere, owing to viscous fluid‐like boundary lubricant film being formed by high hydration of polymer chains. The strong adhesive capability of catechol anchors also prevents polymer chains being sheared off from the substrate during friction tests. The friction responsiveness of PSPMA brushes is observed in electrolyte solution due to the conformation change of polymer chains. The successful functionalization of DLC with polymer brushes affords DLC film excellent biological lubrication and thus will broaden the scope of its applications in biomedical field.
Plasmonic Nanopores in Metal‐Insulator‐Metal Films
Authors: Dahlin Andreas B. , Mapar Mokhtar , Xiong Kunli , Mazzotta Francesco , Höök Fredrik , Sannomiya Takumi
Published: April 2014

A novel type of plasmonic nanopore array in a metal–insulator–metal thin film is presented. The optical properties of this structure are described using a generic theoretical framework for surface waves in a coupled multilayer system. The characteristic spacing (short‐range order) of the pores enables grating‐type coupling to hybridized surface plasmons, with stronger coupling to some modes than others. The nature of the optical resonances and their excitation mechanisms can be conceptually understood from a charge distribution argument. The experimental results are further verified by numerical simulations, which also enable visualization of the near field. This study illustrates the surface plasmon characteristics (sensitive to periodicity) of the extinction maximum in the asymmetric spectral resonance induced by aperture arrays, while the transmission maximum corresponds to a resonance of localized character (sensitive to pore shape). Finally, the use of these nanopores for sensing applications through changes in the refractive index is evaluated.
Tunable Plasmon Enhancement of Gold/Semiconductor Core/Shell Hetero‐Nanorods with Site‐Selectively Grown Shell
Authors: Nan Fan , Liang Shan , Wang Jia‐Hong , Liu Xiao‐Li , Yang Da‐Jie , Yu Xue‐Feng , Zhou Li , Hao Zhong‐Hua , Wang Qu‐Quan
Published: April 2014

Metal/semiconductor Au/Ag2S core/shell hetero‐nanorods with controlled morphology are synthesized and their tunable plasmon enhancements (involving linear and nonlinear optical processes) are demonstrated. The synthesis involves site‐selective deposition of Ag layer onto Au nanorod seeds, followed by site‐selective sulfuration of the Ag layer, resulting in three types of Au/Ag2S core/shell nanorods with complete, corner‐opened, or end‐opened shells. The plasmon resonance and local field confinements varing with shell morphology are analyzed using FDTD calculations. Nonlinear measurements reveal that the Ag2S shell with appropriate morphology leads to the nonlinear refraction and saturable intensity of the Au nanorods increasing 7.6 and 4.1 times, respectively, which indicates strong plasmon enhancements and energy relaxation in the Au/Ag2S core/shell nanorods. This site‐selective shell growth strategy offers a constructive bottom‐up approach to maneuver the optical properties of plasmonic nanocrystals for various applications.
Assessing the Validity of the LOP in the EU Broiler Markets
Authors: Emmanouilides Christos J. , Fousekis Panos
Published: April 2014

The objective of this article is to assess the validity of the Law of One Price (LOP) in five major EU broiler markets. This has been pursued using weekly price data from 1991 to 2012 and recent developments in econometric methodology that account simultaneously for nonstationarity, nonlinearity, and structural breaks. The empirical results provide strong evidence that the LOP holds, predominantly in its weak version. This implies that shocks are fully transmitted from one spatial market to the others, but price differences among them are likely to persist even in the long‐run.
Nasopharyngeal squamous cell carcinoma: a comparative analysis of keratinizing and nonkeratinizing subtypes
Authors: Vazquez Alejandro , Khan Mohemmed N. , Govindaraj Satish , Baredes Soly , Eloy Jean Anderson
Published: April 2014

Background

Nasopharyngeal squamous cell carcinoma (NPSCC) is uncommon in non‐endemic regions. Two major histologic subtypes are recognized: keratinizing (K‐NPSCC) and nonkeratinizing (NK‐NPSCC). We hypothesize that significant differences exist between the 2 in terms of demographic, clinicopathologic, survival, and prognostic features. We aim to show that differentiating between the 2 subtypes is perhaps the most important first step at the time of diagnosis.

Methods

Using a retrospective cohort design, the U.S. National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry was used to extract data on the 2 major subtypes of NPSCC. Frequency, incidence, and relative survival (RS) were analyzed comparatively. Regression analysis was conducted and hazard ratios (HRs) calculated.

Results

A total of 1624 cases were identified: 1234 (76.0%) cases of NK‐NPSCC and 390 (24.0%) cases of K‐NPSCC. Five‐year RS was 60.6% for NK‐NPSCC and 40.5% for K‐NPSCC. Regression analysis revealed K‐NPSCC to be a poor prognostic factor (HR 2.1; 95% confidence interval, 1.8–2.6; p < 0.0001). Other factors associated with a poor prognosis included female gender in K‐NPSCC, age greater than 44 years in both groups, and advanced‐stage disease at diagnosis. Favorable prognostic factors included Asian/Pacific Islander race, and treatment with radiation therapy. Higher histologic grade did not portend a worse prognosis for either group.

Conclusion

NPSCC remains an uncommon malignancy in the United States. K‐NPSCC and NK‐NPSCC represent 2 different histologic entities with important clinical differences. K‐NPSCC carries a worse overall prognosis when compared to NK‐NPSCC.
Modeling of bubble‐size distribution in water and freon co‐blown free rise polyurethane foams
Authors: Niyogi Debdarsan , Kumar Rajinder , Gandhi Kandukuri S.
Published: April 2014

A model has been developed to simulate the foam characteristics obtained, when chemical (water) and physical (Freon) blowing agents are used together for the formation of polyurethane foams. The model considers the rate of reaction, the consequent rise in temperature of the reaction mixture, nucleation of bubbles, and mass transfer of CO2 and Freon to them till the time of gelation. The model is able to explain the experimental results available in literature. It further predicts that the nucleation period gets reduced with increase in water (at constant Freon content), whereas with increase in Freon (at constant water) concentration nucleation period decreases marginally leading to narrower bubble‐size distribution. By the use of uniform sized nuclei added initially, the model predicts that the bubble‐size distribution can be made independent of the rate of homogeneous nucleation and can, thus, offer an extra parameter for its control. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40745.
MgCl2‐supported TiCl4catalysts containing diethyl norbornene‐2,3‐dicarboxylate internal electron donor for 1‐butene polymerization: Effects of internal electron donor configuration
Authors: Dong Xiaofang , Zhang Li , Liu Zhibo , Yang Min , Duan Zhongyu , Hou Kaihu , Liu Binyuan , Kim IL
Published: April 2014

Three isomeric 5‐norbornene‐2,3‐dicarboxylic acid diethyl ester (NDDE) withendo‐,exo‐, andtrans‐configuration have been synthesized and employed as internal electron donors (IED) in 1‐butene polymerization over magnesium chloride supported Ziegler–Natta catalysts. It was found that the configuration of NDDE plays a key role in tuning the catalyst activity, stereospecificity, molecular weight (MW), and polydispersity index (PDI) of resulting poly(1‐butene). The type of catalyst withcis‐5‐norbornene‐endo‐2,3‐dicarboxylic acid diethyl ester as IED shows the highest catalyst activity, while catalyst withtrans‐NDDE as IED yields the poly(1‐butene) with the highest MW and the most broad PDI. IR results showed that the NDDE withendo‐,exo‐, andtrans‐configuration have different coordination way to MgCl2, subsequently affecting the catalysts performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 40758.
Improved hemocompatibility of silk fibroin fabric using layer‐by‐layer polyelectrolyte deposition and heparin immobilization
Authors: Elahi M. Fazley , Guan Guoping , Wang Lu , King Martin W.
Published: April 2014

Silk fibroin has long been used as implantable surgical sutures and it has acceptable mechanical properties and patency rates in animal models and in clinical end‐uses. However, fibroin has been shown to be hemolytic and can cause damage to red blood cells. So to be used as an implantable vascular prosthesis its hemocompatibility needs to be improved. This study has taken two sequential steps to address this problem. First, to create a positively charged layer on the fibroin fibers' surface, a 1.5 and 2.5 bilayers polyelectrolyte surface deposition layer‐by‐layer technique was used with the positive counterion poly(allylamine hydrochloride) and the negative counterion poly(acrylic acid). Second, negatively charged low molecular weight heparin was then immobilized on these positively charged self‐assembled surfaces. The presence of the heparin was confirmed with Alcian Blue staining and a toluidine blue assay, and the increased roughness and hydrophilicity of the modified surfaces were characterized by scanning electron microscopy, contact angle measurements, and atomic force microscopy. In addition, a negligible hemolytic effect, reduced protein adsorption, and a higher concentration of free hemoglobin measured by a kinetic clotting time test were found to be enhanced with the use of 2.5 bilayers compared to the 1.5 bilayers self‐assembly technique. Given the success of these preliminary results, it is anticipated that this novel approach of surface modification and heparin immobilization will demonstrate long‐term patency during future animal trials of small caliber silk fibroin vascular grafts. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40772.
Crystallization and thermal properties of biodegradable polyurethanes based on poly[(R)‐3‐hydroxybutyrate] and their composites with chitin whiskers
Authors: Saad Gamal R. , Salama Hend E. , Mohamed Nadia A. , Sabaa Magdy W.
Published: April 2014

A series of biodegradable polyurethanes (PUs) were synthesized from hydroxylated bacterial poly[(R)‐3‐hydroxybutyrate], P[(R)‐HB]‐diol, as crystallizable hard segment and hydroxyl‐terminated synthetic poly[(R,S)‐3‐hydroxybutyrate), P[(R,S)‐HB]‐diol, as an amorphous soft segment, using 1,6‐hexamethylene diisocyanate, as non‐toxic connecting agent. The P[(R)‐HB] content was varied from 30 to 70 wt %. The resulting copolymers were characterized by FT‐IR, 1H‐NMR, DSC, and TGA. The DSC data revealed that the melting of P[(R)‐HB] segment increases with increasing its own content in the PUs. The cold and melt crystallization are enhanced with increasing P[(R)‐HB] content. The TGA data revealed that the thermal decomposition mainly occurred via a single degradation step and the thermal stability slightly increased with increasing P[(R)‐HB] content. The non‐isothermal crystallization behavior of PU sample containing 40 wt % PHB with and without α‐Chitin whiskers was studied using DSC, and their kinetics data were investigated via the Avrami, Ozawa, and Z.S. Mo methods, respectively. Crystallization activation energy was estimated using Kissinger's method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40784.
Positive impact of a master of science in applied anatomy program on USMLE Step 1 performance
Authors: Fredieu John R. , Snyder Clint W.
Published: April 2014

In this retrospective study of medical student data from Case Western Reserve University School of Medicine, we examined the impact of the Master of Science in Applied Anatomy (MS) program on medical student performance on the United States Medical Licensing Examination® (USMLE®) Step 1 and Step 2. From 2002 to 2010, 1,142 students matriculated as either students in the medical curriculum (MD group; 1,087 students) or MD students who also participated in the MS program (MD/MS group; 55 students). In addition, students were grouped as in either the Western Reserve Curriculum (2002–2005; WR1) or the Western Reserve 2 Curriculum (2006–2010; WR2). Data were analyzed using SPSS statistical package. The mean Medical College Admission Test® (MCAT®) score of all students increased significantly between the WR1 and WR2 curricula [from 32.48 ± 3.73 to 34.00 ± 2.92 (P < 0.00)], but MD and MD/MS students showed similar mean MCAT scores in each curriculum. In contrast, the mean USMLE Step 1 score for the MD/MS group (241.45 ± 18.90) was significantly higher than that of the MD group (229.93 ± 20.65; P < 0.00). The MD/MS group in the WR2 curriculum showed significantly higher USMLE Step 1 scores than the MD group. No significant difference was observed in the USMLE Step 2 Clinical Knowledge scores between the groups. The results show that MD/MS students performed better on the USMLE Step 1 than MD students in the WR2 curriculum, although MCAT scores were similar between the two groups. Together, these results suggest that medical student participation in the Masters in Applied Anatomy program enhances student performance on the USMLE Step 1. Anat Sci Educ 8: 31–36. © 2014 American Association of Anatomists.
Digraphs with Distinguishable Dynamics Under the Multi‐Agent Agreement Protocol
Authors: Rahimian Mohammad Amin , Ajorlou Amir , Aghdam Amir G.
Published: April 2014

This work studies the ability to distinguish digraphs from the output response of some observing agents in a multi‐agent network under the agreement protocol. Given a fixed observation point, it is desired to find sufficient graphical conditions under which the failure of a set of edges in the network information flow digraph is distinguishable from another set. When the latter is empty, this corresponds to the detectability of the former link set given the response of the observing agent. In developing the results, a powerful extension of the all‐minors matrix tree theorem in algebraic graph theory is proved which relates the minors of the transformed Laplacian of a directed graph to the number and length of the shortest paths between its vertices. The results reveal an intricate relationship between the ability to distinguish the responses of a healthy and a faulty multi‐agent network and the inter‐nodal paths in their information flow digraphs. The results have direct implications for the operation and design of multi‐agent systems subject to multiple link losses. Simulations and examples are presented to illustrate the analytic findings.
Robust Partially Mode Delay‐Dependent ℋ∞ Output Feedback Control of Discrete‐Time Networked Control Systems
Authors: Chae Seunghwan , Huang Dan , Nguang Sing Kiong
Published: April 2014

In this paper, a methodology for designing an output feedback controller for discrete‐time networked control systems has been considered. More precisely, network‐induced delays between the sensor and the controller is modelled by a Markov chain with transition probabilities which are not assumed to be fully known. The systems parameter uncertainties are assumed to be norm‐bounded and possibly time‐varying. To the best of the authors knowledge, the problem of designing a partially mode delay‐dependent output feedback controller for NCSs with partially known transition probability matrix has not been investigated in the literature. Based on the Lyapunov‐Krasovskii functional approach, sufficient conditions for the existence of a robust partially mode delay‐dependent output feedback controller are given in terms of bilinear matrix inequalities which can be solved using a cone complementarity linearization algorithm. The proposed design methodology differs from the existing design methodologies in that dynamic output feedback controllers are parameterized by both modes and transition probabilities, as opposed to the existing design approaches which parameterize controllers by modes only. The results obtained reduce to the existing results on fully known transition matrices when transition probabilities are fully known. It is shown that the proposed methodology can be applied to real world systems. The proposed design methodology is verified by using a DC servo motor system where the plant and the controller are connected via a cellular network with partially known transition probability matrix.
Intelligent Adaptive Trajectory Tracking Control for an Autonomous Small‐Scale Helicopter Using Fuzzy Basis Function Networks
Authors: Tsai Ching‐Chih , Wang Zen‐Chung , Lee Chi‐Tai , Li Yi‐Yu
Published: April 2014

This paper presents an intelligent adaptive trajectory tracking controller using fuzzy basis function networks (FBFN) for an autonomous small‐scale helicopter. The FNFN is used online to learn the vehicle mass and the coupling effect between the force and the moments, and the intelligent adaptive controller then is synthesized systematically using a backstepping technique. This controller is designed to accomplish the ultimate boundedness of the closed‐loop helicopter dynamics and accommodate agile flight maneuvers. Two nonlinear simulations on hovering and trajectory tracking are conducted to show the effectiveness and merit of the proposed controller, which is also shown to be superior by performance comparison with a well‐known neural‐network controller.
Nature‐inspired nanoformulations for contrast‐enhanced in vivo MR imaging of macrophages
Authors: Sigalov Alexander B.
Published: April 2014

Magnetic resonance imaging (MRI) of macrophages in atherosclerosis requires the use of contrast‐enhancing agents. Reconstituted lipoprotein particles that mimic native high‐density lipoproteins (HDL) are a versatile delivery platform for Gd‐based contrast agents (GBCA) but require targeting moieties to direct the particles to macrophages. In this study, a naturally occurring methionine oxidation in the major HDL protein, apolipoprotein (apo) A‐I, was exploited as a novel way to target HDL to macrophages. We also tested if fully functional GBCA–HDL can be generated using synthetic apo A‐I peptides. The fluorescence and MRI studies reveal that specific oxidation of apo A‐I or its peptides increases the in vitro macrophage uptake of GBCA–HDL by 2–3 times. The in vivo imaging studies using an apo E‐deficient mouse model of atherosclerosis and a 3.0 T MRI system demonstrate that this modification significantly improves atherosclerotic plaque detection using GBCA–HDL. At 24 h post‐injection of 0.05 mmol Gd kg−1 GBCA–HDL containing oxidized apo A‐I or its peptides, the atherosclerotic wall/muscle normalized enhancement ratios were 90 and 120%, respectively, while those of GBCA–HDL containing their unmodified counterparts were 35 and 45%, respectively. Confocal fluorescence microscopy confirms the accumulation of GBCA–HDL containing oxidized apo A‐I or its peptides in intraplaque macrophages. Together, the results of this study confirm the hypothesis that specific oxidation of apo A‐I targets GBCA–HDL to macrophages in vitro and in vivo. Furthermore, our observation that synthetic peptides can functionally replace the native apo A‐I protein in HDL further encourages the development of these contrast agents for macrophage imaging. Copyright © 2014 John Wiley & Sons, Ltd.
A smartphone‐centric platform for remote health monitoring of heart failure
Authors: Bisio Igor , Lavagetto Fabio , Marchese Mario , Sciarrone Andrea
Published: April 2014

Heart failure is a chronic disease that alternates intense and weak phases and requires repeated and frequent hospital treatments. The use of automatic instruments for a remote and ubiquitous monitoring of biological parameters relevant to heart failure pathophysiology offers new perspectives to improve the patients' quality of life and the efficacy of the treatment.

The platform described in this paper represents an implementation of an automatic remote monitoring tool where smartphones play a crucial role. They are not employed just to communicate through traditional client‐server applications and they are not only the hub of information sent by sensors, but they also act as intelligent processors and autonomous sensors of the patients' motion through a high‐accuracy activity recognition algorithm. The proposed platform combines the evolution of health systems and the consequent needs of modern telemedicine with the current context‐aware capability of recent smartphones, obtained by implementing specific algorithmic solutions, and with the anything, anytime, and anywhere communication capability of the pervasive communications paradigm. Performance evaluation focuses on the accuracy of the activity recognition estimation, on its applicability to real life, and on the data exchange between smartphones and medical server, allowing to envisage the potential of the designed platform. Copyright © 2014 John Wiley & Sons, Ltd.
An efficient distributed routing protocol for wireless sensor networks with mobile sinks
Authors: Shi Lei , Yao Zheng , Zhang Baoxian , Li Cheng , Ma Jian
Published: April 2014

Introducing mobile sinks into a wireless sensor network can effectively improve the network performance. However, sink mobility can bring excessive protocol overhead for route maintenance and may offset the benefit from using mobile sinks. In this paper, we propose a dynamic layered routing protocol to address this problem. The proposed protocol integrates dynamic layered Voronoi scoping and dynamic anchor selection to effectively reduce the dissemination scopes and frequencies of routing updates as the sinks move in the network. Simulation results show that the proposed protocol can effectively reduce the protocol overhead while ensuring high packet delivery ratio as compared with existing work. Copyright © 2014 John Wiley & Sons, Ltd.
Connection‐Strength Estimation of Neuronal Networks by Fitting for Izhikevich Model
Authors: Isomura Takuya , Takeuchi Akimasa , Shimba Kenta , Kotani Kiyoshi , Jimbo Yasuhiko
Published: April 2014

Recently, there has been abundant research using multineuron recording, but there are many problems with extracting the features from the obtained spike time series, which are huge in volume and complex. Here we introduce a new method of estimating synaptic connection strengths between neurons by fitting to the Izhikevich model by maximum likelihood estimation. We demonstrate that our method can estimate connection strengths from spike time series given by a simulated neural ensemble and can estimate nonconnectivity between two independent cultured neuronal networks. These results suggest that our method is applicable to network and plasticity analysis of neuronal networks.
Overvoltages on DC Side of Power Conditioning System Caused by Lightning Stroke to Structure Anchoring Photovoltaic Panels
Authors: Yamamoto Kazuo , Takami Jun , Okabe Narimitsu
Published: April 2014

Photovoltaic (PV) power plants and wind turbines are eco‐friendly power generators that utilize solar energy and wind energy, respectively. Many large‐scale PV power plants have been constructed using government subsidies. Large‐scale PV power plants are usually constructed in large open spaces that contain some tall structures. Therefore, such large‐scale PV power plants are likely to attract lightning, which may result in the malfunction or breakdown of electrical and electronic equipment. In this investigation, overvoltages generated when a lightning strikes a structure anchoring PV panels were measured using a 1:10 scale model. The measurements were also verified using the finite‐difference time‐domain method. The mechanisms of overvoltage generation on an actual‐scale PV power plant were also clarified.
Enantiopure Conducting Salts of Dimethylbis(ethylenedithio)tetrathiafulvalene (DM‐BEDT‐TTF) with the Hexachlororhenate(IV) Anion
Authors: Pop Flavia , Allain Magali , Auban‐Senzier Pascale , Martínez‐Lillo José , Lloret Francesc , Julve Miguel , Canadell Enric , Avarvari Narcis
Published: April 2014

The enantiopure radical cation salts [(S,S)‐DM‐BEDT‐TTF]4[ReCl6] ([(S,S)‐1]4[ReCl6]) and [(R,R)‐DM‐BEDT‐TTF]4[ReCl6] ([(R,R)‐1]4[ReCl6]) [DM‐BEDT‐TTF = dimethylbis(ethylenedithio)tetrathiafulvalene] have been prepared by electrocrystallization of the chiral precursor DM‐BEDT‐TTF in the presence of NBu4[ReCl5(pyrazine)] (NBu4 = tetra‐n‐butylammonium cation; pyz = pyrazine) as supporting electrolyte. The single‐crystal X‐ray analysis shows that the compounds crystallize in the triclinic system, non‐centrosymmetric space group P1, and that the donors arrange in parallel columns. The four independent donor molecules possess approximate charges of +1, +1/2, +1/2 and 0, according to the structural parameter analysis and band‐structure calculations, which also support the semiconducting behaviour of the materials. The rhenium(IV) ion in both compounds is six‐coordinate with six chloro atoms that describe a slightly distorted octahedral environment with Re–Cl distances that cover the short range 2.348–2.374 Å. Magnetic measurements on polycrystalline samples of [(S,S)‐1]4[ReCl6] and [(R,R)‐1]4[ReCl6] have been investigated in the temperature range 2–295 K. They are practically identical and confirm the presence of high‐spin S = 3/2 [ReCl6]2– isolated monomers together with a Pauli paramagnetism, typical of this kind of system. The magnetic susceptibility data are thoroughly reproduced over the whole temperature range with a simple model of isolated S = 3/2 ions with a zero‐field splitting plus a temperature‐independent paramagnetism (TIP), and the best‐fit parameters being gRe = 1.875(2), |D| = 4.50(3) cm–1 and TIP = 3630(20)×10–6 cm3 mol–1 (2D is the energy gap between the MS = ±3/2 and MS = ±1/2 Kramers doublets).
Synthesis and characterization of novel vinylester prepolymers from cardanol
Authors: Jaillet Fanny , Nouailhas Hélène , Auvergne Rémi , Ratsimihety Amédée , Boutevin Bernard , Caillol Sylvain
Published: April 2014

A novel thermosetting vinylester (VE) resin was prepared form cardanol, coming from cashew nut shell liquid (CNSL), a renewable resource and waste of the cashew industry. A VE cardanol‐based prepolymer was synthesized by reacting commercial cardanol diepoxy and methacrylic acid. The VE cardanol‐based prepolymer was polymerized by free radical polymerization to yield a thermoset resin with different monomers used as reactive diluents such as styrene (ST), isobornyl methacrylate (IBOMA), dibutyl itaconate (DBI), butanediol dimethacrylate (BDDMA), and hexanediol dimethacrylate (HDDMA). The resulting VE resin was characterized by TGA, DSC, and DMA analyses and compared to diglycidyl ether of bisphenol A (DGEBA)‐based VE resin. Cardanol‐based VE resins exhibit interesting mechanical and thermal properties for composite materials. The Tg value is 86°C with 40% by mass of ST and 116°C with 40% by mass of IBOMA. Around 70°C of Tg are lost compared to DGEBA‐based VE resin, whereas with an oil‐based VE resin the loss of Tg value is around 150°C.

Practical application: The acrylated cardanol‐based monomer described in this contribution, that is, acrylated cardanol from CNSL, provided new biobased aromatic building blocks for further free radical polymerizations with various reactive diluents. The obtained VE materials are partially biobased and may be used as binders in composite applications.

Biobased vinylester prepolymer (VE) was synthesized by acrylation of commercial di‐epoxy cardanol (Cardolite NC514), coming from CNSL. Vinylester materials were synthesized by free radical polymerization of VE with various monomers. Mechanical and thermal properties of obtained materials showed that synthesized vinylester material could lead to binders for composite application.
Sulfoximine‐Based Modular Enantioselective Synthesis of Azaspirocycles Featuring Sulfoximine Displacement, Dianion Cycloalkylation, RCM and N‐Acyliminium Ion Formation
Authors: Köhler (née Adrien) Adeline , Raabe Gerhard , Runsink Jan , Köhler Franz , Gais Hans‐Joachim
Published: April 2014

We describe a modular, enantioselective synthesis of functionalised azaspirocycles with a range of ring sizes. The synthesis exploits the special features of sulfoximines, including chirality, carbanion‐stabilisation, nucleophilicity, and nucleofugacity. Diastereoselective intramolecular amination of hydroxyalkyl‐substituted cycloalkenylsulfoximines by the carbamate method gave bicyclic oxazinanones containing an amino‐substituted tertiary C atom. Cycloalkylation of the corresponding C,N‐dianions with biselectrophiles afforded sulfoximine‐substituted spirocycles. Monoalkylation of the C,N‐dianions with functionalised electrophiles, having a double bond and acetal group, furnished the corresponding C‐alkylated bicyclic sulfoximines. Displacement of the sulfoximine group of bicyclic and spirocyclic sulfoximines by haloformate reactions gave the corresponding halides (Cl, I). Alkylation of the bicyclic halides with functionalised cuprates and reduction of the sulfoximine‐substituted bicycles, carrying an alkyl group at the Cα atom, gave starting materials for a step‐wise construction of the heterocyclic ring. Ring‐closing metathesis of a bicyclic C,N‐dienyl derivative furnished the corresponding spirocycle with an unsaturated piperidine ring. Cyclisation of an acetal group containing bicyclic oxazinanone gave spirocycles containing O,N‐acetal and enamide groups. The diastereoselective reaction of a spirocyclic O,N‐acetal with an allylsilane furnished the corresponding spirocycle, carrying an allyl group at the C atom adjacent to the N atom. Attempts to lithiate a bicyclic carbamate at the CH2 group adjacent to the N atom were not successful.
Gold‐Catalyzed 5‐endo‐dig Cyclization of 2‐[(2‐Aminophenyl)ethynyl]phenylamine with Ketones for the Synthesis of Spiroindolone and Indolo[3,2‐c]quinolone Scaffolds
Authors: Reddy Basi. V. Subba , Swain Manisha , Reddy S. Madhusudana , Yadav J. S. , Sridhar B.
Published: April 2014

A tandem gold‐catalyzed 5‐endo‐dig/spirocyclization of 2‐[(2‐aminophenyl)ethynyl]phenylamines with isatins was achieved to produce the corresponding 5′,11′‐dihydrospiro[indoline‐3,6′‐indolo[3,2‐c]quinolin]‐2‐one derivatives in good yields with high regioselectivity. This reaction proceeded well at ambient temperature under mild conditions. Ketones also participated smoothly under similar conditions to produce 6,6‐disubstituted‐6,11‐dihydro‐5H‐indolo[3,2‐c]quinolones.