bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging short‐lived reactive oxygen species (ROS) with endogenous contrast MRI
Authors: Tain Rong‐Wen , Scotti Alessandro M. , Li Weiguo , Zhou Xiaohong Joe , Cai Kejia
Published: May 2017

Purpose

To characterize the relaxation properties of reactive oxygen species (ROS) for the development of endogenous ROS contrast magnetic resonance imaging (MRI).

Materials and Methods

ROS‐producing phantoms and animal models were imaged at 9.4T MRI to obtain T1 and T2 maps. Egg white samples treated with varied concentrations of hydrogen peroxide (H2O2) were used to evaluate the effect of produced ROS in T1 and T2 for up to 4 hours. pH and temperature changes due to H2O2 treatment in egg white were also monitored. The influences from H2O2 itself and oxygen were evaluated in bovine serum albumin (BSA) solution producing no ROS. In addition, dynamic temporal changes of T1 in H2O2‐treated egg white samples were used to estimate ROS concentration over time and hence the detection sensitivity of relaxation‐based endogenous ROS MRI. The relaxivity of ROS was compared with that of Gd‐DTPA as a reference. Finally, the feasibility of in vivo ROS MRI with T1 mapping acquired using an inversion recovery sequence was demonstrated with a well‐established rotenone‐treated mouse model (n = 6).

Results

pH and temperature changes in treated egg white samples were insignificant (<0.1 unit and <1°C, respectively). T1 relaxation time in the H2O2‐treated egg white was reduced significantly (P < 0.05), while there was only small reduction in T2 (<10%). In the H2O2‐treated BSA solution that produce no ROS, there was a small change in T1 due to H2O2 itself (±1%), although a significant T2‐shortening effect was observed (>10%, P < 0.05). Also, there was a small reduction in T1 (13 ± 1%) and T2 (1 ± 2%) from molecular oxygen. The detection sensitivity of ROS MRI was estimated around 10 pM. The T1 relaxivity of ROS was found to be much higher than that of Gd‐DTPA (3.4 × 107 vs. 0.9 s−1·mM−1). Finally, significantly reduced T1 was observed in rotenone‐treated mouse brain (5.1 ± 2.5%, P < 0.05).

Conclusion

We demonstrated in the study that endogenous ROS MRI based on the paramagnetic effect has sensitivity for in vitro and in vivo applications.

Level of Evidence: 2

Technical Efficacy Stage: 2

J. Magn. Reson. Imaging 2018;47:222–229.
Characterization and circulation of seasonal influenza viruses in Madrid, 2010‐2016
Authors: Chiarella Flavia C. , Daoud Zarife , Fuentes‐Ferrer Manuel E. , Ramos Amador José T. , Picazo Juan J. , Culebras Esther
Published: May 2017

Influenza virus infection is a major health care burden and is associated with significant morbidity and mortality. The 2009 influenza pandemic highlighted the importance of influenza surveillance. The objective of this study was to assess the epidemiology and activity of influenza A and B viruses in adults and children in the post‐pandemic period with a special focus on the pediatric population. We performed a retrospective descriptive study involving adults and children with influenza‐like illness at the Clinico San Carlos Hospital (Madrid, Spain) over six influenza seasons, between August 2010 and April 2016. Respiratory specimens were collected from 3131 patients and routinely processed for influenza diagnosis. Epidemiological analysis was performed in terms of gender, age, and seasonal distribution. Globally, Influenza A and B viruses were detected in the respiratory specimens of 696 (22.2%) of the 3131 studied population. Among all influenza positive specimens, 142 (20.4%) were influenza A(H1N1)pdm09, 61 (8.8%) were influenza A(H3N2), 321 (46.1%) were untypeable influenza A viruses and 166 (23.9%) were influenza B. Co‐infection by both influenza A and B viruses was detected in six patients (0.9%). Meanwhile, co‐infection with other non‐influenza respiratory viruses was identified in 5 children and 20 adults. Influenza A(H1N1)pdm09 virus activity has been significantly high since the 2009 pandemic and has gradually replaced the previously circulating seasonal influenza A(H1N1) virus. Moreover, influenza A(H3N2) virus activity remained at low levels during the last winter season while influenza B virus isolates increased significantly over the past 2 years.
Neutral and alkaline cellulases: Production, engineering, and applications
Authors: Ben Hmad Ines , Gargouri Ali
Published: May 2017

Neutral and alkaline cellulases from microorganisms constitute a major group of the industrial enzymes and find applications in various industries. Screening is the important ways to get novel cellulases. Most fungal cellulases have acidic pH optima, except some fungi like Humicola insolens species. However, new applications require the use of neutral and alkaline cellulases in food, brewery and wine, animal feed, textile and laundry, pulp and paper industries, agriculture as well in scientific research purposes. Indeed, the demand for these enzymes is growing more rapidly than ever before, and becomes the driving force for research on engineering the cellulolytic enzymes. Here, we present an overview of the biotechnological research for neutral and alkaline cellulases.
Pioppino mushroom in southern Italy: an undervalued source of nutrients and bioactive compounds
Authors: Landi Nicola , Pacifico Severina , Ragucci Sara , Di Giuseppe Antonella MA , Iannuzzi Federica , Zarrelli Armando , Piccolella Simona , Di Maro Antimo
Published: May 2017

BACKGROUND

Agrocybe aegerita (V. Brig.) Singer, commonly known as Pioppino, is a popular edible mushroom, known in the Campania Region (Italy). Despite its habitual consumption, little nutritional and biochemical information is available. Thus, nutritional values, anti‐radical properties and chemical composition of the wild Pioppino were compared to those of the cultivated Agaricus bisporus (J.E. Lange) Imbach (known as Champignon), equally analysed.

RESULTS

Macronutrient components (proteins, carbohydrates and lipids), free and protein amino acids and fatty acid content of poplar mushroom were achieved. Total phenol content of a defatted Pioppino alcoholic extract (PM) was determined, whereas DPPH and ABTS methods were applied to determine the radical scavenging capabilities of the extract. Ferricyanide and ORAC‐fluorescein methods were also performed. Finally, LC‐HRMS was used to identify and quantify the main metabolites in the extract. PM was mainly constituted of disaccharides, hexitol derivatives and malic acid. Coumaric acid isomers and C6C1 compounds were also detected.

CONCLUSION

All data revealed that wild Pioppino is an excellent functional food, by far exceeding that of the Champignon. Therefore, these data are useful to promote the consumption of this mushroom encouraging thus its biological cultivation, due to wild availability is strongly compromised by the extensive use of fungicides. © 2017 Society of Chemical Industry
Weed interference with peppermint (Mentha x piperita L.) and spearmint (Mentha spicata L.) crops under different herbicide treatments: effects on biomass and essential oil yield
Authors: Karkanis Anestis , Lykas Christos , Liava Vasiliki , Bezou Anna , Petropoulos Spyridon , Tsiropoulos Nikolaos
Published: May 2017

BACKGROUND

‘Minor crops’ such as spearmint and peppermint are high added value crops, despite the fact that their production area is comparably small worldwide. The main limiting factor in mint commercial cultivation is weed competition. Thus, field experiments were carried out to evaluate the effects of weed interference on growth, biomass and essential oil yield in peppermint and spearmint under different herbicide treatments.

RESULTS

The application of pendimethalin and oxyfluorfen provided better control of annual weeds resulting in higher crop yield. Additionally, when treated with herbicides both crops were more competitive against annual weeds in the second year than in the first year. All pre‐emergence herbicides increased biomass yield, since pendimethalin, linuron and oxyfluorfen reduced the density of annual weeds by 71–92%, 63–74% and 86–95%, respectively. Weed interference and herbicide application had no effect on essential oil content; however, a relatively strong impact on essential oil production per cultivated area unit was observed, mainly due to the adverse effect of weed interference on plant growth.

CONCLUSION

Considering that pendimethalin and oxyfluorfen were effective against annual weeds in both spearmint and peppermint crops, these herbicides should be included in integrated weed management systems for better weed management in mint crops. © 2017 Society of Chemical Industry
Body Mass Normalization for Lateral Abdominal Muscle Thickness Measurements in Adolescent Athletes
Authors: Linek Pawel
Published: May 2017

Objectives

To determine the value of allometric parameters for ultrasound measurements of the oblique external (OE), oblique internal (OI), and transversus abdominis (TrA) muscles in adolescent athletes. The allometric parameter is the slope of the linear regression line between the log‐transformed body mass and log‐transformed muscle size measurement.

Methods

The study included 114 male adolescent football players between the ages of 10 and 19 years. All individuals with no surgical procedures performed on the trunk area and who had played a sport for at least 2 years were included. A real‐time B‐mode ultrasound scanner with a linear array transducer was used to obtain images of the lateral abdominal muscles from both sides of the body. A stabilometric platform was used to assess the body mass value.

Results

The correlations between body mass and the OE, OI, and TrA muscle thicknesses were r = 0.73, r = 0.79, and r = 0.64, respectively (in all cases, P < .0001). The allometric parameters were 0.77 for the OE, 0.67 for the OI, and 0.61 for the TrA. Using these parameters, no significant correlations were found between body mass and the allometric‐scaled thickness of the lateral abdominal muscles.

Conclusions

Significant positive correlations exist between body mass and lateral abdominal muscle thickness in adolescent athletes. Therefore, it is reasonable to advise that the values of the allometric parameters for the OE, OI, and TrA muscles obtained in this study should be used, and the allometric‐scaled thicknesses of those muscles should be analyzed in future research on adolescent athletes.
A Prospective Evaluation of Transverse Tracheal Sonography During Emergent Intubation by Emergency Medicine Resident Physicians
Authors: Lahham Shadi , Baydoun Jamie , Bailey James , Sandoval Sandra , Wilson Sean P. , Fox John C. , Slattery David E.
Published: May 2017

Objectives

Establishing a definitive airway is often the first step in emergency department treatment of critically ill patients. Currently, there is no agreed upon consensus as to the most efficacious method of airway confirmation. Our objective was to determine the diagnostic accuracy of real‐time sonography performed by resident physicians to confirm placement of the endotracheal tube during emergent intubation.

Methods

We performed a prospective cohort study of adult patients in the emergency department undergoing emergent endotracheal intubation. Thirty emergency medicine residents, who were blinded to end‐tidal carbon dioxide detection results, performed real‐time transverse tracheal sonography during intubation to evaluate correct endotracheal tube placement.

Results

Seventy‐two patients were enrolled in the study. Sixty‐eight instances (94.4%) were interpreted as correct placement in the trachea; 4 (5.6%) were interpreted as esophageal, of which 1 was a false‐negative finding, therefore conferring sensitivity of 98.5% (95% confidence interval, 92.1%–99.9%) and specificity of 75.0% (95% confidence interval, 19.4%–99.4%) for correct placement. There was no significant difference in accuracy among resident sonographers with different levels of residency training.

Conclusions

A simple transverse tracheal sonographic examination performed by emergency medicine resident physicians can be used as an adjunct to help confirm correct endotracheal tube placement during intubation. In our cohort, the level of training did not appear to affect the ability of residents to correctly identify the endotracheal tube position.
Point‐of‐Care Diagnosis of Cardiac Tamponade Identified by the Flow Velocity Paradoxus
Authors: Shyy William , Knight Roneesha S. , Kornblith Aaron , Teismann Nathan A.
Published: May 2017

The presentation of cardiac tamponade is a spectrum from occult to extreme. The clinical history, physical exam, electrocardiogram, and radiographic findings of tamponade have poor sensitivities and even worse specificities. We use a clinical scenario to demonstrate how point‐of‐care cardiac ultrasound can diagnose impending cardiac tamponade in a clinically stable patient. The ultrasound finding we recommend is the flow velocity paradoxus, in which respiratory variation causes significant changes in transvalvular inflow velocities, which are exaggerated when tamponade is present. The management of a pericardial effusion depends on its physiologic effect, and point‐of‐care ultrasound directly measures that effect and expedites patient care.
Elevated alkaline phosphatase activity in a phosphate‐replete environment: Influence of sinking particles
Authors: Davis Clare E. , Mahaffey Claire
Published: May 2017

Alkaline phosphatase activity (APA) is traditionally a proxy for phosphate (DIP)‐limitation because it is induced by DIP‐limited microbes to access the labile ester fraction of the organic phosphorus (OP) pool. Here, we present multi‐year summertime depth distributions of APA and enzyme kinetics in the DIP‐replete Celtic Sea. Our findings support the cumulating body of evidence that APA has a potentially widespread role in OP remineralization through the water column. APA and Vmax were positively correlated with depth and DIP, with total APA being threefold higher below (0.93 ± 0.32 nM P h−1) compared to above the thermocline (0.30 ± 0.24 nM P h−1, p < 0.001). Separation of particles by sinking speed demonstrated that APA was eightfold higher on fast sinking (Ffast) particles compared to slow sinking particles (Fslow; p < 0.05). When normalized to particulate organic carbon (POC) and bacterial production (BP), APAPOC and APABP associated with Ffast (0.76 ± 0.10 nmol P μmol C−1 h−1, 21.13 ± 2.2 nmol P nmol C−1, respectively) were fourfold and 25‐fold higher compared to the combined APA associated with dissolved plus suspended (Fsusp) and Fslow fractions (0.19 ± 0.06 nmol P μmol C−1 h−1 and 0.84 ± 0.23 nmol P nmol C−1, respectively). We postulate that this may reflect enhanced ectoenzyme activity associated with bacteria colonizing particle surfaces and/or release by zooplankton via faecal pellet excretion. Knowledge of the disparity between APA and BP associated with particle and dissolved phases is required to accurately define the O2 : P ratio of regenerated P derived from sinking particles as a result of AP‐facilitated remineralization.
Phosgene‐Free Syntheses and Hydrolytic Properties of Water‐Soluble Polyhydroxyurethanes with Ester–Carbonate–Ether Structures in Their Main Chains
Authors: Matsukizono Hiroyuki , Endo Takeshi
Published: May 2017

Three types of bifunctional 6‐membered cyclic carbonates bearing ester, acyclic carbonate or ether moieties have been derived from nonexpensive trimethylolpropane or di(trimethylolpropane) through phosgene‐free routes and used for the polyaddition reaction with 1,3‐diaminopropane to design polyhydroxyurethanes (PHUs) containing the corresponding linkages in their main chains. Furthermore, these PHUs have been chemically modified via their OH groups to afford water‐soluble PHUs (WSPHUs) and characterized for their hydrolytic properties at different pH conditions. Carbonate and ester bonds in these WSPHUs are easily hydrolyzed under basic conditions and their hydrolytic rates depend on their main chain structures; WSPHUs bearing carbonate structures are degraded faster than WSPHUs with ester linkages, while WSPHUs having ether bonds are slowest hydrolyzed. Moreover, the hydrolytic rates of these WSPHUs can be modulated by the copolymerization of these monomers at different feed ratios.

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Characterizing bacterial communities in paper production—troublemakers revealed
Authors: Zumsteg Anita , Urwyler Simon K. , Glaubitz Joachim
Published: May 2017

Biofilm formation is a major cause of reduced paper quality and increased down time during paper manufacturing. This study uses Illumina next‐generation sequencing to identify the microbial populations causing quality issues due to their presence in biofilms and slimes. The paper defects investigated contained traces of the films and/or slime of mainly two genera, Tepidimonas and Chryseobacterium. The Tepidimonas spp. found contributed on average 68% to the total bacterial population. Both genera have been described previously to be associated with biofilms in paper mills. There was indication that Tepidimonas spp. were present as compact biofilm in the head box of one paper machine and was filtered out by the paper web during production. On the other hand Tepidimonas spp. were also present to a large extent in the press and white waters of two nonproblematic paper machines. Therefore, the mere presence of a known biofilm producer alone is not sufficient to cause slimes and therefore paper defects and other critical factors are additionally at play. For instance, we identified Acidovorax sp., which is an early colonizer of paper machines, exhibiting the ability to form extracellular DNA matrices for attachment and biofilm formation.
Matrix method based on the shifted Chebyshev polynomials for solving fractional‐order PDEs with initial‐boundary conditions
Authors: Zhao Fuqiang , Huang Qingxue , Xie Jiaquan , Ma Lifeng
Published: May 2017

In the current study, we consider the approximate solutions of fractional‐order PDEs with initial‐boundary conditions based on the shifted Chebyshev polynomials. The proposed method is combined with the operational matrix of fractional‐order differentiation described in the Caputo's sense. The main characteristic behind this approach is to reduce such problems to those of solving systems of algebraic equations with constant coefficients by dispersing unknown variables. The validity and effectiveness of the approach are demonstrated via some numerical examples. Lastly, the error analysis of the proposed method has been investigated. Copyright © 2017 John Wiley & Sons, Ltd.
Fully integrated 3D high‐resolution multicontrast abdominal PET‐MR with high scan efficiency
Authors: Kolbitsch Christoph , Neji Radhouene , Fenchel Matthias , Mallia Andrew , Marsden Paul , Schaeffter Tobias
Published: May 2017

Purpose

To provide 3D multicontrast anatomical MR with high isotropic resolution and metabolic positron emission tomography (PET) images using a respiratory motion‐compensated simultaneous PET‐MR examination with high scan efficiency.

Theory and Methods

Standard abdominal PET‐MR examinations combine MR data obtained during multiple breath‐holds with free‐breathing PET acquisitions, limiting the achievable image resolution and potentially causing misalignment errors between breath‐hold and free‐breathing data. Here, a 3D free‐breathing PET‐MR acquisition is presented, yielding T1 and T2‐weighted MR images with an isotropic resolution of 1.5 mm3. In addition, nonrigid respiratory motion information and respiratory‐resolved attenuation‐correction maps are obtained without an increase in scan time. Motion information is used in motion‐compensated image reconstructions to improve MR and PET image quality while shortening scan times.

Results

The proposed approach was evaluated in 11 oncology patients and provided respiratory motion information with an accuracy of 1.3 ± 0.1 mm. Sharpness of anatomical features was increased by 19 ± 13% compared with the uncorrected MR images in a 54 ± 26% shorter scan time than a gated MR acquisition. The MR‐based motion information improved uptake values (75 ± 94%) and resolution (16 ± 27%) of simultaneously acquired PET images.

Conclusions

The proposed method provides motion‐compensated 3D high‐quality MR and PET images in a comprehensive and highly efficient examination. Magn Reson Med 79:900–911, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
Phase‐field material point method for brittle fracture
Authors: Kakouris E. G. , Triantafyllou S. P.
Published: May 2017

The material point method for the analysis of deformable bodies is revisited and originally upgraded to simulate crack propagation in brittle media. In this setting, phase‐field modelling is introduced to resolve the crack path geometry. Following a particle in cell approach, the coupled continuum/phase‐field governing equations are defined at a set of material points and interpolated at the nodal points of an Eulerian, ie, non‐evolving, mesh. The accuracy of the simulated crack path is thus decoupled from the quality of the underlying finite element mesh and relieved from corresponding mesh‐distortion errors. A staggered incremental procedure is implemented for the solution of the discrete coupled governing equations of the phase‐field brittle fracture problem. The proposed method is verified through a series of benchmark tests while comparisons are made between the proposed scheme, the corresponding finite element implementation, and experimental results.
Level set shape and topology optimization of finite strain bilateral contact problems
Authors: Lawry Matthew , Maute Kurt
Published: May 2017

This paper presents a method for the optimization of multicomponent structures comprised of 2 and 3 materials considering large motion sliding contact and separation along interfaces. The structural geometry is defined by an explicit level set method, which allows for both shape and topology changes. The mechanical model assumes finite strains, a nonlinear elastic material behavior, and a quasi‐static response. Identification of overlapping surface position is handled by a coupled parametric representation of contact surfaces. A stabilized Lagrange method and an active set strategy are used to model frictionless contact and separation. The mechanical model is discretized by the extended FEM, which maintains a clear definition of geometry. Face‐oriented ghost penalization and dynamic relaxation are implemented to improve the stability of the physical response prediction. A nonlinear programming scheme is used to solve the optimization problem, which is regularized by introducing a perimeter penalty into the objective function. Design sensitivities are determined by the adjoint method. The main characteristics of the proposed method are studied by numerical examples in 2 dimensions. The numerical results demonstrate improved design performance when compared to models optimized with a small strain assumption. Additionally, examples with load path dependent objectives display nonintuitive designs.
Episodic Volunteering at a Religious Megaevent
Authors: Cnaan Ram A. , Daniel Heist H. , Storti Melissa Heinlein
Published: May 2017

In preparation for Pope Francis's visit to Philadelphia and the 2015 World Meeting of Families, organizers looked for thousands of volunteers to help carry out these events. This is common for many one‐time and episodic events, such as large sporting events (from marathons to Special Olympics), arts and cultural events (such as festivals and concerts), and fundraising events. After the pope's visit, volunteers were asked to respond to a questionnaire about their experiences and the volunteer management of the event; 2,408 responded (34.4 percent). Data on motivation, who volunteered, recruitment, training, assignment, supervision, communication, satisfaction, and suggestions for improvement were elicited. We focused on episodic volunteering at a religious event and on a broad spectrum of issues pertaining to management of episodic volunteers. Our findings add to the knowledge regarding volunteer management and also add to conceptual understanding of the distinction between ongoing and episodic volunteers.
Indonesian healthy living intentions: Segmentation study insights
Authors: Arli Denni , Dietrich Timo , Tkaczynski Aaron , Rundle‐Thiele Sharyn
Published: May 2017

Obesity is a global epidemic. The very rapid growth rates of obesity prevalence observed in developing countries is alarming. Segmentation is under applied in social marketing and, when it is applied, it is based primarily on demographic data in samples drawn from developed nations. The current study adopts psychographic segmentation to understand lifestyle attitudes and intentions towards exercise and weight loss among an Indonesian sample. TwoStep cluster analysis (n = 499) identified 4 distinct segments (At risk, Conscious healthy, Overweight, and Tryers). The results of this study demonstrate that different groups exist in the larger population and that consideration of these groups may assist social marketers in creating service/intervention offerings that meet the needs of a broader range of people in the market, thus extending penetration of campaigns that address obesity.
Do consumers consider Word of Mouth for crucial life decisions?
Authors: Bhayani Ali
Published: May 2017

This study reexamines the Theory of Reasoned Action in a culture with higher uncertainty avoidance and power distance and analyzes how homophily and the ability (expertise) of word of mouth (WOM) sources impacts on the consumer attitudes and purchase decisions with respect to such high‐risk credence products as college selection. By using an interpretivist approach to model building, the study comprises 41 interviews, finding that WOM made a significant impact on attitudes but not on purchase behaviors. Homophily with friends was regarded as an important factor at the search stage, but strong ties were more important in the purchasing of the product. Expertise and the credibility of the WOM played a significant role in generating trust in WOM, resulting in attitude change, although with a minimal impact on purchase behavior. The article concludes with implications for practice.
Reinventing the rattling tin: How UK charities use Facebook in fundraising
Authors: Lucas Evie
Published: May 2017

Using a multicase study approach, this paper explores how the three biggest UK cancer charities by donations use Facebook in their fundraising campaigns, in order to facilitate understanding of the dynamics of philanthropic asking in a social networking site‐mediated environment. The analysis reveals that Facebook is primarily used to strengthen relationships with supporters, mainly via humanising the brand, fostering obligations, and encouraging social interaction. The mobilization of these relationships in fundraising is facilitated by persuasive strategies, including public recognition, authority, and the fostering of a sense of efficacy among fans, and the most common outcome of this mobilization is public endorsement of charities' fundraising campaigns via sharing. At a time when harsh public spending cuts have left gaps in charity funding that need to be filled by philanthropy, this study aims to make a practical contribution to knowledge by examining what works and how in Facebook fundraising.
The Hidden Face of Wine Polyphenol Polymerization Highlighted by High‐Resolution Mass Spectrometry
Authors: Vallverdú‐Queralt Anna , Meudec Emmanuelle , Eder Matthias , Lamuela‐Raventos Rosa M. , Sommerer Nicolas , Cheynier Véronique
Published: May 2017

Polyphenols, including tannins and red anthocyanin pigments, are responsible for the color, taste, and beneficial health properties of plant‐derived foods and beverages, especially in red wines. Known compounds represent only the emerged part of the “wine polyphenol iceberg”. It is believed that the immersed part results from complex cascades of reactions involving grape polyphenols and yeast metabolites. We used a non‐targeted strategy based on high‐resolution mass spectrometry and Kendrick mass defect plots to explore this hypothesis. Reactions of acetaldehyde, epicatechin, and malvidin‐3‐O‐glucoside, representing yeast metabolites, tannins, and anthocyanins, respectively, were selected for a proof‐of‐concept experiment. A series of compounds including expected and so‐far‐unknown structures were detected. Random polymerization involving both the original substrates and intermediate products resulting from cascade reactions was demonstrated.
Aging of polyamide 12 in oil at different temperatures and pressures
Authors: Hernández José Leonardo Monroy , d'Almeida José Roberto Moraes
Published: May 2017

Polyamide 12 (PA 12) is an alternative to steel in the manufacture of pipes for transporting oil and gas. However, polyamide pipes suffer degradation, triggered by factors such as temperature and exposure to chemicals. In this research, the authors studied the variation of mechanical and thermal properties and of structural characteristics of a PA 12 grade after aging in oil. The aging process lasted 3360 h. It was made at ambient temperature and at 70 °C, under pressures of 1 and 17 atm. At ambient temperature and atmospheric pressure, PA 12 increased in volume, weight and rigidity, and decreased in damping. At 70 °C and atmospheric pressure, there was a smaller increase in volume and weight. PA 12 samples also darkened, showed an increase in crystallinity and damping, and a decrease in rigidity. At 70 °C and 17 atm, a decrease in volume and weight was observed; the samples also darkened, increased in crystallinity and rigidity, and decreased in damping. In all aging conditions, the results of the thermal analysis and the analysis of functional groups showed that the chemical structure of the material was not significantly changed. According to the results, PA 12 has a good resistance to aging under these conditions. Copyright © 2017 John Wiley & Sons, Ltd.
Synergistic effect of hybrid graphene and boron nitride on the cure kinetics and thermal conductivity of epoxy adhesives
Authors: Singh Amit Kumar , Panda Bishnu Prasad , Mohanty Smita , Nayak Sanjay Kumar , Gupta Manoj Kumar
Published: May 2017

In the present study, the synergistic effect of hybrid boron nitride (BN) with graphene on the thermal conductivity of epoxy adhesives has been reported. Graphene was prepared by chemical reduction of graphite oxide (GO) in a mixture of concentrated H2SO4/H3PO4 acid. The particle size distribution of GO was found to be ~10 μm and a low contact angle of 54° with water indicated a hydrophilic surface. The structure of prepared graphene was characterized by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM). The thermal conductivity of adhesives was measured using guarded hot plate technique. Test results indicated an improvement in the thermal conductivity up to 1.65 W/mK, which was about ninefold increase over pristine epoxy. Mechanical properties of different epoxy formulations were also measured employing lap shear test. The surface characterization of different epoxy adhesive systems was characterized through XRD, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. Fourier transform infrared also served to determine the nature of interactions between filler particles and epoxy resin. Non‐isothermal differential scanning calorimetric (DSC) technique was used to investigate the effects of graphene and BN particles on the cure kinetics and cross‐linking reaction of epoxy cured with amine curing agent. The Kissinger equation, the model‐free isoconversional Flynn–Wall–Ozawa method and the Ozawa model were used to analyze the kinetic parameter. Copyright © 2017 John Wiley & Sons, Ltd.
Room temperature deformable shape memory composite with fine‐tuned crystallization induced via nanoclay particles
Authors: Sun Yu‐Chen , Cai Shenyang , Ren Jie , E. Naguib Hani
Published: May 2017

It is known that particular types of semi‐crystalline/elastomer polymer blends exhibit shape memory effects (SME) due to the dispersion of two immiscible phases. In this study, the crystal structure of polylactic acid (PLA)/ thermoplastic polyurethane (TPU) based shape memory polymer (SMP) is altered by incorporating small amounts of montmorillonite (MMT) nanoclay. The results indicate the incorporation of MMT can improve the compatibility of the two different polymers. Moreover, the presence of MMT affects the total crystallinity of the SMP and improves mechanical properties. Lastly, uniaxial stretching deformation can be applied to the SMP at room temperature conditions while maintaining its shape memory properties. With 1 wt % MMT particles, the recovery ratio (Rr) was nearly 95%, which indicated a strong recovery effect. The shape‐fixing ratio (Rf) remained above 95% for all composites due to plastic deformation applied at room temperature. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1197–1206
A multiband Eliashberg‐approach to iron‐based superconductors
Authors: Efremov Dmitry V. , Drechsler Stefan‐Ludwig , Rosner Helge , Grinenko Vadim , Dolgov Oleg V.
Published: May 2017

Since the discovery of the Fe‐based superconductors (FeSC) a lot of efforts has been applied to elucidate the microscopic mechanism behind cooper pairing and the symmetry of the order parameter. Examination of effective interactions of electrons with spin‐fluctuations in these systems yield that couplings are not weak and the materials have to be considered in a strong coupling scheme. In the present article, we review some aspects of the description of iron‐based superconductors in the frame of the Eliashberg approach for multiband systems. The application of the Eliashberg scheme is demonstrated with two compounds Ba0.6K0.4Fe2As2 and Ca0.32Na0.68Fe2As2. In both cases, it was found that these materials are in the intermediate coupling regime. Further, we consider effects of impurities on physical properties of multiband superconductors. It is demonstrated that the impurities affect nontrivially the superconducting properties. In particular, they may trigger a symmetry change of superconducting order parameters. This effect can be used for determination of the superconducting order parameter. Finally, we consider KFe2As2 and show that its thermodynamic properties are consistent with a nodal superconducting order parameter.
Elastic, electronic, and dielectric properties of bulk and monolayer ZrS2, ZrSe2, HfS2, HfSe2 from van der Waals density‐functional theory
Authors: Zhao Qiyi , Guo Yaohui , Si Keyu , Ren Zhaoyu , Bai Jintao , Xu Xinlong
Published: May 2017

The elastic, electronic, and dielectric properties of layered transition metal dichalcogenides MX2 (M = Zr and Hf; X = S, Se) have been investigated using density functional theory (DFT) with van der Waals correction. The elastic modulus indicate that the structures belong to brittle materials. The band gaps of these materials through Heyd–Scuseria–Ernzerhof hybrid functional are in reasonable agreement with the experimental data. Partial density of state analysis suggests that the metallic atoms play a dominant role in the conduction band and the chalcogenide atoms have the main effect on the valence band. The presence of peaks in the dielectric constant spectra mainly result from the transition between first, second, third valence bands and the first conduction bands and the direction is from Γ to M, M to K, and K to Γ of the high symmetry k‐points for bulk and monolayer structures, respectively. What is more, parallel band effect has been observed in monolayer structures, which suggests strong light‐matter interactions in these materials. This work promotes the property understanding of these materials and holds potential for the development of optoelectronic devices based on these layered materials.
Magnetic order and phase diagram of magnetic alloy system: MgxNi1–xO alloy
Authors: Li Mingkai , Long Debing , Ahuja Rajeev , He Yunbin
Published: May 2017

The antiferromagnetic phase diagram of MgxNi1−xO alloy was reexamined theoretically by multicomponent cluster expansion method. It predicts antiferromagnetic state in the alloy with high Mg content, instead of a mixture of antiferromagnetic and paramagnetic states, which was deduced previously from neutron diffraction results. The theoretically found intermediate antiferromagnetic ground states at Mg contents of xMg = 0.25 and 0.75 exhibit very low neutron diffraction intensities, which leads to confusion with paramagnetic state. Our approach here reduced remarkably the computation time in searching the intermediate ground states as well as calculating the magnetic phase diagram.
The effect of the fluorine loading on the optoelectronic and photovoltaic properties of (X‐DADAD‐)n‐type donor–acceptor copolymers with the benzothiadiazole A units
Authors: Akkuratov Alexander V. , Susarova Diana K. , Inasaridze Liana N. , Troshin Pavel A.
Published: May 2017

We synthesized and investigated novel low bandgap (X‐DADAD‐)n‐type donor–acceptor copolymers comprising non‐fluorinated 2,1,3‐benzothiadiazole (BT) and the fluorine‐containing 5,6‐difluoro‐2,1,3‐benzothiadiazole (ffBT) as the electron acceptor blocks (A). The introduction of fluorine substituents was shown to influence optical, electrochemical, and morphological properties of the polymers, as well as their photovoltaic performance. Optimized bulk heterojunction solar cells based on the fluorine‐loaded polymer P2 showed improved characteristics (efficiency of 5.2%) as compared to the reference cells based on the non‐fluorinated polymer P1 (efficiency of 4.4%).
Estimates of subgroup treatment effects in overall nonsignificant trials: To what extent should we believe in them?
Authors: Tanniou Julien , van der Tweel Ingeborg , Teerenstra Steven , Roes Kit C.B.
Published: May 2017

In drug development, it sometimes occurs that a new drug does not demonstrate effectiveness for the full study population but appears to be beneficial in a relevant subgroup. In case the subgroup of interest was not part of a confirmatory testing strategy, the inflation of the overall type I error is substantial and therefore such a subgroup analysis finding can only be seen as exploratory at best. To support such exploratory findings, an appropriate replication of the subgroup finding should be undertaken in a new trial. We should, however, be reasonably confident in the observed treatment effect size to be able to use this estimate in a replication trial in the subpopulation of interest. We were therefore interested in evaluating the bias of the estimate of the subgroup treatment effect, after selection based on significance for the subgroup in an overall “failed” trial. Different scenarios, involving continuous as well as dichotomous outcomes, were investigated via simulation studies. It is shown that the bias associated with subgroup findings in overall nonsignificant clinical trials is on average large and varies substantially across plausible scenarios. This renders the subgroup treatment estimate from the original trial of limited value to design the replication trial. An empirical Bayesian shrinkage method is suggested to minimize this overestimation. The proposed estimator appears to offer either a good or a conservative correction to the observed subgroup treatment effect hence provides a more reliable subgroup treatment effect estimate for adequate planning of future studies.
Nepetoidin B, a Natural Product, Inhibits LPS‐stimulated Nitric Oxide Production via Modulation of iNOS Mediated by NF‐κB/MKP‐5 Pathways
Authors: Wu Xiaxia , Gao Hongwei , Sun Wen , Yu Jie , Hu Hao , Xu Qiongming , Chen Xiuping
Published: May 2017

Previous reports showed that nepetoidin B (NTB), a natural product isolated from many herbs, has anti‐fungal and anti‐bacterial effects. In this study, the antiinflammatory effect of NTB was investigated in lipopolysaccharide (LPS)‐stimulated RAW 264.7 macrophages. The cytotoxic effect of NTB and LPS was determined by MTT assay. The nitric oxide (NO) production was detected by Griess assay. The TNF‐α and IL‐6 levels were determined by enzyme‐linked immunosorbent assay kits. Protein expressions were tested by western blotting. The transcription activity of inducible nitric oxide synthase (iNOS) was detected by luciferase assay. Immunofluorescence assay was used to observe the visualization of NF‐κB/p65 nuclear translocation. NTB and LPS showed no obvious cytotoxic effect on RAW 264.7 cells. NTB remarkably inhibited LPS‐induced NO and TNF‐α secretion in a concentration‐dependent manner while showed no significant effect on IL‐6 secretion. NTB inhibited LPS‐induced iNOS protein expression and transcription activity without affecting cyclooxygenase‐2. Furthermore, NTB suppressed LPS‐stimulated NF‐κB/p65 phosphorylation and nuclear translocation. In addition, NTB significantly inhibited LPS‐induced phosphorylation of JNK1/2 and p38MAPK without affecting ERK1/2. LPS‐induced inhibition of mitogen‐activated protein kinase phosphatase‐5 (MKP‐5) was completely reversed by NTB. In conclusion, these results suggested that NTB inhibited LPS‐stimulated NO production possibly via modulation of iNOS mediated by MKP‐5/NF‐κB pathways in RAW 264.7 cells. Copyright © 2017 John Wiley & Sons, Ltd.
Effect of raindrop size distribution and rain rate inhomogeneity on the relationship between attenuation and depolarization
Authors: Chodkaveekityada Peeramed , Fukuchi Hajime
Published: May 2017

In addition to attenuation, depolarization due to rain is another factor that degrades satellite propagation signals, especially in the higher frequency bands and in places that have high rates of rainfall. A formula to predict cross‐polarization as a function of attenuation has been proposed, and it is derived by a theoretical calculation using frequency, the forward scattering amplitude of raindrops, rainfall rates, the raindrop size distribution (DSD), and various other propagation parameters. In this paper, a formula for predicting cross‐polarization is derived on the basis of the assumption of a gamma‐type DSD up to 100 GHz. These results are compared with conventional exponential‐type DSDs, such as the Marshall‐and‐Palmer DSD. Moreover, for a more realistic propagation situation, we consider the effect on the aforementioned relationship of rainfall rate inhomogeneity along the propagation path. It is shown that, for practical purposes, this inhomogeneity does not have a significant effect on satellite propagation. Copyright © 2017 John Wiley & Sons, Ltd.
Allogeneic Bone Marrow-Derived Mesenchymal Stromal Cells Expanded In Vitro for Treatment of Aplastic Anemia: A Multicenter Phase II Trial
Authors: Pang Yan , Xiao Hao-Wen , Zhang Hang , Liu Zeng-Hui , Li Li , Gao Yang , Li Hong-Bo , Jiang Zu-Jun , Tan Huo , Lin Jing-Ren , Du Xin , Weng Jian-Yu , Nie Da-Nian , Lin Dong-Jun , Zhang Xiang-Zhong , Liu Qi-Fa , Xu Duo-Rong , Chen Hai-Jia , Ge Xiao-Hu , Wang Xiao-Yan , Xiao Yang
Published: May 2017

We conducted a phase II, noncomparative, multicenter study to assess the efficacy and safety of allogeneic bone marrow-derived mesenchymal stromal cells (BM-MSCs) expanded in vitro for patients with aplastic anemia (AA) refractory to immunosuppressive therapy. Seventy-four patients from seven centers received allogeneic BM-MSCs at a dose of 1–2 × 106 cells/kg per week for 4 weeks. Responses were assessed at 0.5, 1, 2, 3, 6, 9, and 12 months after the first cells infusion. Patients with response at 1 month continued to receive four infusions. All patients were evaluable. The overall response rate was 28.4% (95% confidence interval, 19%–40%), with 6.8% complete response and 21.6% partial response. The median times to response of leukocytic, erythrocytic, and megakaryocytic linages were 19 (range, 11–29), 17 (range, 12–25), and 31 (range, 26–84) days, respectively. After median follow-up of 17 months, overall survival was 87.8%. Seven patients developed transitory and mild headache and fever, but no other adverse events were observed. Antithymocyte globulin used in previous treatment and no activated infection throughout treatment were predictors for response. Allogeneic BM-MSCs infusion is a feasible and effective treatment option for refractory AA. The trial was registered at www.clinicaltrials.gov as NCT00195624.
Modeling Static and Dynamic Kinetics of Microstructural Evolution in Hot Deformation of Fe–0.15C–0.2Si–1.4Mn–0.03Nb Alloy
Authors: Meng Yi , Lin Jin‐Yu , Yanagida Akira , Yanagimoto Jun
Published: May 2017

To achieve microstructural refinement of ferrous alloys by using severe plastic deformation (SPD) methods, investigation of the microstructural evolution during hot deformation near the austenite–ferrite transformation temperature of ferrous alloys is necessary. In this study, a series of single and double‐compression tests of cylindrical Fe–0.15C–0.2Si–1.4Mn–0.03Nb specimens are conducted in the temperature range from 750 to 900 °C. On the basis of experimental results, inverse analysis, micrographic investigation, finite element method (FEM) analysis, and regression analysis are carried out to obtain the material genome for Fe–0.15C–0.2Si–1.4Mn–0.03Nb alloy, which describes the static and dynamic kinetics of microstructural evolution of this alloy. The validity and feasibility of the proposed material genome are verified by compression tests of hourglass‐shaped specimens and subsequent micrographic investigation.
Analytical study of the response of reinforced concrete walls with discontinuities of flag wall type
Authors: Massone Leonardo M. , Rojas Fabian R. , Ahumada Matias G.
Published: May 2017

Slender walls with discontinuities at their bases, such as flag walls or walls with door openings or access, are common in Chilean practice because of the architectural requirements at facades, first floors, and underground levels. However, there is limited information about the behavior of such elements, and no designs or guidelines in the current codes consider the effects of discontinuities at the base. In this work, two analytical models are presented that estimate the yield displacement, yield curvature, and ultimate curvature of walls with openings, such as flag walls (setback), based on the dimensions of the opening and the longitudinal boundary steel ratio calibrated from a parametric analysis of a nonlinear finite element model. The results indicate that these discontinuities can have a major impact on the elastic displacement, reducing it because of the presence of a more rigid section above the opening, and also on the inelastic component, by increasing the curvature (and the strain) at the wall base because the opening tends to confine the plastic hinge within that area.
Large‐eddy simulations with extremum‐seeking control for individual wind turbine power optimization
Authors: Ciri Umberto , Rotea Mario , Santoni Christian , Leonardi Stefano
Published: May 2017

Large‐eddy simulations of the flow past an array of three aligned turbines have been performed. The study is focused on below rated (Region 2) wind speeds. The turbines are controlled through the generator torque gain, as usually done in Region 2. Two operating strategies are considered: (i) preset individual optimum torque gain based on a model for the power coefficient (baseline case) and (ii) real‐time optimization of torque gain for maximizing each individual turbine power capture during operation. The real‐time optimization is carried out through a model‐free approach, namely, extremum‐seeking control. It is shown that ESC is capable of increasing the power production of the array by 6.5% relative to the baseline case. The extremum‐seeking control reduces the torque gain of the downstream turbines, thus increasing the angular speed of the blades. This results in improved aerodynamics near the tip of the blade that is the portion contributing mostly to the torque and power. In addition, an increase in angular speed leads to a larger entrainment in the wake, which also contributes to provide additional available power downstream. It is also shown that the tip speed ratio may not be a reliable performance indicator when the turbines are in waked conditions. This may be a concern when using optimal parameter settings, determined from isolated turbine models, in applications with waked turbines. Copyright © 2017 John Wiley & Sons, Ltd.