bluuebunny/crossref_metadata_2025 huggingface dataset:
Burst Pressures for Toriconical Shells: Experimental and Numerical Approach
Authors: Błachut J. , Ifayefunmi O.
Published: June 2017

The paper describes burst pressures of eight mild steel toriconical shells and proposes a criterion for their ultimate loss of structural integrity based on true stress–strain material relationship. All test models were initially loaded by quasi-static external pressure until they buckled/collapsed. They were subsequently internally pressurized until burst. The details about the numerical process, which simulates the two-stage loading process, i.e., starting with buckling by external pressure being followed by reloading using internal pressure for up to the burst, are given. The paper concentrates on numerical procedure, which allows computation of the burst pressure using extensive plastic straining. It is shown that burst pressures based on the excessive plastic straining are closer to reality (and experiments) than those based on plastic instability.
Measurements of the Effects of Streamwise Riblets on Boundary Layer Turbulence
Authors: Ancrum Derek B. , Yaras Metin I.
Published: June 2017

This study presents experimental results on the effects of riblets on the coherent structures of turbulence within a turbulent spot. The riblet spacings of the study correspond to 0.5 and 1.5 times the natural spacing of the low-speed streak. The cross-sectional dimensions of the riblets were chosen to control the spatial distribution of wave packets consisting of streamwise-aligned hairpin vortices. Both riblet spacings demonstrated effective control on the spanwise positioning of the wave packets. The wider-spaced riblets reduced spanwise mutual interaction between wave packets. The closer-spaced riblets promoted this interaction via spanwise-oriented vortical structures which produced stronger turbulent fluctuations.
Effects of Sterilization on Shape Memory Polyurethane Embolic Foam Devices
Authors: Muschalek Rachael , Nash Landon , Jones Ryan , Hasan Sayyeda M. , Keller Brandis K. , Monroe Mary Beth B. , Maitland Duncan J.
Published: June 2017

Polyurethane shape memory polymer (SMP) foams have been developed for various embolic medical devices due to their unique properties in minimally invasive biomedical applications. These polyurethane materials can be stored in a secondary shape, from which they can recover their primary shape after exposure to an external stimulus, such as heat and water exposure. Tailored actuation temperatures of SMPs provide benefits for minimally invasive biomedical applications, but incur significant challenges for SMP-based medical device sterilization. Most sterilization methods require high temperatures or high humidity to effectively reduce the bioburden of the device, but the environment must be tightly controlled after device fabrication. Here, two probable sterilization methods (nontraditional ethylene oxide (ntEtO) gas sterilization and electron beam irradiation) are investigated for SMP medical devices. Thermal characterization of the sterilized foams indicated that ntEtO gas sterilization significantly decreased the glass transition temperature. Further material characterization was undertaken on the electron beam (ebeam) sterilized samples, which indicated minimal changes to the thermomechanical integrity of the bulk foam and to the device functionality.
Analysis and Prediction of Fluid Flow Behavior in Progressing Cavity Pumps
Authors: Al-Safran Eissa , Aql Ahmed , Nguyen Tan
Published: June 2017

A progressing cavity pump (PCP) is a positive displacement pump with an eccentric screw movement, which is used as an artificial lift method in oil wells. Downhole PCP systems provide an efficient lifting method for heavy oil wells producing under cold production, with or without sand. Newer PCP designs are also being used to produce wells operating under thermal recovery. The objective of this study is to develop a set of theoretical operational, fluid property, and pump geometry dimensionless groups that govern fluid flow behavior in a PCP. A further objective is to correlate these dimensionless groups to develop a simple model to predict flow rate (or pressure drop) along a PCP. Four PCP dimensionless groups, namely, Euler number, inverse Reynolds number, specific capacity number, and Knudsen number were derived from continuity, Navier–Stokes equations, and appropriate boundary conditions. For simplification, the specific capacity and Knudsen dimensionless groups were combined in a new dimensionless group named the PCP number. Using the developed dimensionless groups, nonlinear regression modeling was carried out using large PCP experimental database to develop dimensionless empirical models of both single- and two-phase flow in a PCP. The developed single-phase model was validated against an independent single-phase experimental database. The validation study results show that the developed model is capable of predicting pressure drop across a PCP for different pump speeds with 85% accuracy.
Theoretical Investigation on Inflow Between Two Rotating Disks
Authors: Singh Achhaibar
Published: June 2017

Mathematical relations are obtained for velocities and pressure distribution for a fluid entering the peripheral clearance of a pair of rotating concentric disks that converges and discharges through an opening at the center. Both, the flows in the gap of corotating disks and in the gap of contrarotating disks can be predicted using the present analytical solutions. The prediction of instability of radial velocity for corotating disks at the speed ratio of unity is very important for practical applications. The radial velocity profile is similar to a parabolic profile exactly at speed ratio of unity. The profile drastically changes with the small difference of ±1% in the disks’ rotation. The radial convection was observed in the tangential velocity at a low radius. Centrifugal force caused by disk rotation highly influences the flow resulting in backflow on the disks. The pressure consists of friction losses and convective inertia. Therefore, the pressure decrease is high for increased speed ratio, throughflow Reynolds number, and rotational Reynolds number. The pressure decrease for the flow between contrarotating disks is lesser than that for the flow between corotating disks due to decreased viscous losses in the tangential direction. This study provides valuable guidance for the design of devices where disks are rotated independently by highlighting the instabilities in the radial velocity at the speed ratio of unity.
An Assessment of the Two-Layer Quasi-Laminar Theory of Relaminarization Through Recent High-Re Accelerated Turbulent Boundary Layer Experiments
Authors: Ranjan Rajesh , Narasimha Roddam
Published: June 2017

The phenomenon of relaminarization is observed in many flow situations, including that of an initially turbulent boundary layer (TBL) subjected to strong favorable pressure gradients (FPG). As several experiments on relaminarizing flows have indicated, TBLs subjected to high pressure gradients do not follow the universal log-law, and (for this and other reasons) the prediction of boundary layer (BL) parameters using current turbulence models has not been successful. However, a quasi-laminar theory (QLT; proposed in 1973), based on a two-layer model to explain the later stages of relaminarization, showed good agreement with the experimental data available at that time. These data were mostly at relatively low Re and hence left the precise role of viscosity undefined. QLT, therefore, could not be assessed at high-Re. Recent experiments, however, have provided more comprehensive data and extended the Reynolds number range to nearly 5 × 103 in momentum thickness. These data provide a basis for a reassessment of QLT, which is revisited here with an improved predictive code. It is demonstrated that even for these high-Re flows subjected to high acceleration, QLT provides good agreement with experimental results, and therefore, has the potential to substitute for Reynolds-averaged Navier–Stokes (RANS) simulations in high FPG regions.
A Computational Study on the Effects of Surface Tension and Prandtl Number on Laminar-Wavy Falling-Film Condensation
Authors: Nabil Mahdi , Rattner Alexander S.
Published: June 2017

Characterization of wavy film heat and mass transfer is essential for numerous energy-intensive chemical and industrial applications. While surface tension is the underlying cause of film waviness, widely used correlations for falling-film heat transfer do not account for surface tension magnitude as a governing parameter. Furthermore, although the effect of Prandtl number on wavy falling-film heat transfer has been highlighted in some studies, it is not included in most published Nusselt number correlations. Contradictory trends for Nusselt number variation with Prandtl number are found in correlations that do account for such effects. A systematic simulation-based parametric study is performed here to determine the individual effects of Reynolds, Prandtl, capillary, and Jakob numbers on heat transfer in laminar-wavy falling-films. First-principles based volume-of-fluid (VOF) simulations are performed for wavy falling condensation with varying fluid properties and flow rates. A sharp surface tension volumetric force model is employed to predict wavy interface behavior. The numerical model is first validated for smooth falling-film condensation heat transfer and wavy falling-film thickness. The simulation approach is applied to identify Nusselt number trends with Reynolds, Prandtl, capillary, and Jakob numbers. Finally, based on the collected simulation data, a new Nusselt number correlation for laminar-wavy falling-film condensation is proposed.
Low temperature SiOx thin film deposited by plasma enhanced atomic layer deposition for thin film encapsulation applications
Authors: Lee Young-Soo , Han Ju-Hwan , Park Jin-Seong , Park Jozeph
Published: June 2017

Silicon oxide (SiOx) films were synthesized by plasma enhanced atomic layer deposition (PEALD) using di-isopropylaminosilane [SiH3N(C3H7)2] as the precursor and an oxygen plasma as the reactant. The layers were characterized with respect to different growth temperatures between 60 and 150 °C. The film density and surface roughness values measured by x-ray reflectometry and atomic force microscopy all approached those of thermally grown SiOx. Also, reasonably high breakdown voltages were observed at all deposition temperatures. An interesting phenomenon involves the fact that the SiOx layer deposited at 60 °C is most effective as a moisture barrier, as it exhibits the lowest water vapor transmission rate. X-ray photoelectron spectroscopy analyses indicate that the silicon monoxide bonding characteristic becomes more pronounced as the growth temperature decreases. It is conjectured that such a difference in the bonding state renders the surface of the low temperature SiOx films rather hydrophobic, which suppresses the penetration of moisture. The results indicate that low temperature PEALD SiOx films may be suitable for thin film encapsulation applications in mechanical flexible platforms.
Grafting of architecture controlled poly(styrene sodium sulfonate) onto titanium surfaces using bio-adhesive molecules: Surface characterization and biological properties
Authors: Chouirfa Hamza , Evans Margaret D. M. , Castner David G. , Bean Penny , Mercier Dimitri , Galtayries Anouk , Falentin-Daudré Céline , Migonney Véronique
Published: June 2017

This contribution reports on grafting of bioactive polymers such as poly(sodium styrene sulfonate) (polyNaSS) onto titanium (Ti) surfaces. This grafting process uses a modified dopamine as an anchor molecule to link polyNaSS to the Ti surface. The grafting process combines reversible addition-fragmentation chain transfer polymerization, postpolymerization modification, and thiol-ene chemistry. The first step in the process is to synthetize architecture controlled polyNaSS with a thiol end group. The second step is the adhesion of the dopamine acrylamide (DA) anchor onto the Ti surfaces. The last step is grafting polyNaSS to the DA-modified Ti surfaces. The modified dopamine anchor group with its bioadhesive properties is essential to link bioactive polymers to the Ti surface. The polymers are characterized by conventional methods (nuclear magnetic resonance, size exclusion chromatography, and attenuated total reflection-Fourier-transformed infrared), and the grafting is characterized by x-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and quartz crystal microbalance with dissipation monitoring. To illustrate the biocompatibility of the grafted Ti-DA-polyNaSS surfaces, their interactions with proteins (albumin and fibronectin) and cells are investigated. Both albumin and fibronectin are readily adsorbed onto Ti-DA-polyNaSS surfaces. The biocompatibility of modified Ti-DA-polyNaSS and control ungrafted Ti surfaces is tested using human bone cells (Saos-2) in cell culture for cell adhesion, proliferation, differentiation, and mineralization. This study presents a new, simple way to graft bioactive polymers onto Ti surfaces using a catechol intermediary with the aim of demonstrating the biocompatibility of these size controlled polyNaSS grafted surfaces.
Comparison of metrological techniques for evaluation of the impact of a cosmetic product containing hyaluronic acid on the properties of skin surface
Authors: Janiš Rahula , Pata Vladimír , Egner Pavlína , Pavlačková Jana , Zapletalová Andrea , Kejlová Kristina
Published: June 2017

The aim of this research was to evaluate mutual interchangeability of four principally different biometric instrumental techniques designed for objective measurement of changes in the physical, mechanical, and topographical properties of the skin surface treated with commercial antiaging cosmetic products with hyaluronic acid. The following instrumental devices were used: Visioscope PC 35, Corneometer Multiprobe Adapter MPA 6, Reviscometer RVM 600, and 3D scanner Talysurf CLI 500. The comparison of the individual methods was performed using cluster analysis. The study involved 25 female volunteers aged 40–65. Measurements were taken before and after 30 daily in vivo applications of an antiaging preparation to the skin surface in the periorbital area. A slight reduction in skin surface roughness was recorded in 55% of the volunteers. On the contrary, a worsening from their initial states was detected in 25% of the subjects, while for 20%, no significant change was reported. Cluster analysis confirmed that the mentioned methodologies can be divided into two basic clusters, namely, a cluster of methods recording the changes in skin relief by means of optical techniques, and a cluster of methods investigating changes in hydration and anisotropy. In practice, the techniques in different clusters are not interchangeable and should be assessed separately.
Effect of inhomogeneous temperature fields on acoustic streaming structures in resonators
Authors: Červenka Milan , Bednařík Michal
Published: June 2017

Acoustic streaming in 2D rectangular resonant channels filled with a fluid with a spatial temperature distribution is studied within this work. An inertial force is assumed for driving the acoustic field; the temperature inhomogeneity is introduced by resonator walls with prescribed temperature distribution. The method of successive approximations is employed to derive linear equations for calculation of primary acoustic and time-averaged secondary fields including the streaming velocity. The model equations have a standard form which allows their numerical integration using a universal solver; in this case, COMSOL Multiphysics was employed. The numerical results show that fluid temperature variations in the direction perpendicular to the resonator axis influence strongly the streaming field if the ratio of the channel width and the viscous boundary layer thickness is big enough; the streaming in the Rayleigh vortices can be supported as well as opposed, which can ultimately lead to the appearance of additional vortices.
The Malaria Parasite Cyclin H Homolog PfCyc1 Is Required for Efficient Cytokinesis in Blood-Stage
Plasmodium falciparum
Authors: Robbins Jonathan A. , Absalon Sabrina , Streva Vincent A. , Dvorin Jeffrey D.
Published: June 2017

All well-studied eukaryotic cell cycles are driven by cyclins, which activate cyclin-dependent kinases (CDKs), and these protein kinase complexes are viable drug targets. The regulatory control of the
Plasmodium falciparum
cell division cycle remains poorly understood, and the roles of the various CDKs and cyclins remain unclear. The
P. falciparum
genome contains multiple CDKs, but surprisingly, it does not contain any sequence-identifiable G
1
-, S-, or M-phase cyclins. We demonstrate that
P. falciparum
Cyc1 (PfCyc1) complements a G
1
cyclin-depleted
Saccharomyces cerevisiae
strain and confirm that other identified malaria parasite cyclins do not complement this strain. PfCyc1, which has the highest sequence similarity to the conserved cyclin H, cannot complement a temperature-sensitive yeast cyclin H mutant. Coimmunoprecipitation of PfCyc1 from
P. falciparum
parasites identifies PfMAT1 and PfMRK as specific interaction partners and does not identify PfPK5 or other CDKs. We then generate an endogenous conditional allele of PfCyc1 in blood-stage
P. falciparum
using a destabilization domain (DD) approach and find that PfCyc1 is essential for blood-stage proliferation. PfCyc1 knockdown does not impede nuclear division, but it prevents proper cytokinesis. Thus, we demonstrate that PfCyc1 has a functional divergence from bioinformatic predictions, suggesting that the malaria parasite cell division cycle has evolved to use evolutionarily conserved proteins in functionally novel ways.

IMPORTANCE
Human infection by the eukaryotic parasite
Plasmodium falciparum
causes malaria. Most well-studied eukaryotic cell cycles are driven by cyclins, which activate cyclin-dependent kinases (CDKs) to promote essential cell division processes. Remarkably, there are no identifiable cyclins that are predicted to control the cell cycle in the malaria parasite genome. Thus, our knowledge regarding the basic mechanisms of the malaria parasite cell cycle remains unsatisfactory. We demonstrate that
P. falciparum
Cyc1 (PfCyc1), a transcriptional cyclin homolog, complements a cell cycle cyclin-deficient yeast strain but not a transcriptional cyclin-deficient strain. We show that PfCyc1 forms a complex in the parasite with PfMRK and the
P. falciparum
MAT1 homolog. PfCyc1 is essential and nonredundant in blood-stage
P. falciparum
. PfCyc1 knockdown causes a stage-specific arrest after nuclear division, demonstrating morphologically aberrant cytokinesis. This work demonstrates a conserved PfCyc1/PfMAT1/PfMRK complex in malaria and suggests that it functions as a schizont stage-specific regulator of the
P. falciparum
life cycle.
A Herpesviral Immediate Early Protein Promotes Transcription Elongation of Viral Transcripts
Authors: Fox Hannah L. , Dembowski Jill A. , DeLuca Neal A.
Published: June 2017

Herpes simplex virus 1 (HSV-1) genes are transcribed by cellular RNA polymerase II (RNA Pol II). While four viral immediate early proteins (ICP4, ICP0, ICP27, and ICP22) function in some capacity in viral transcription, the mechanism by which ICP22 functions remains unclear. We observed that the FACT complex (comprised of SSRP1 and Spt16) was relocalized in infected cells as a function of ICP22. ICP22 was also required for the association of FACT and the transcription elongation factors SPT5 and SPT6 with viral genomes. We further demonstrated that the FACT complex interacts with ICP22 throughout infection. We therefore hypothesized that ICP22 recruits cellular transcription elongation factors to viral genomes for efficient transcription elongation of viral genes. We reevaluated the phenotype of an ICP22 mutant virus by determining the abundance of all viral mRNAs throughout infection by transcriptome sequencing (RNA-seq). The accumulation of almost all viral mRNAs late in infection was reduced compared to the wild type, regardless of kinetic class. Using chromatin immunoprecipitation sequencing (ChIP-seq), we mapped the location of RNA Pol II on viral genes and found that RNA Pol II levels on the bodies of viral genes were reduced in the ICP22 mutant compared to wild-type virus. In contrast, the association of RNA Pol II with transcription start sites in the mutant was not reduced. Taken together, our results indicate that ICP22 plays a role in recruiting elongation factors like the FACT complex to the HSV-1 genome to allow for efficient viral transcription elongation late in viral infection and ultimately infectious virion production.

IMPORTANCE
HSV-1 interacts with many cellular proteins throughout productive infection. Here, we demonstrate the interaction of a viral protein, ICP22, with a subset of cellular proteins known to be involved in transcription elongation. We determined that ICP22 is required to recruit the FACT complex and other transcription elongation factors to viral genomes and that in the absence of ICP22 viral transcription is globally reduced late in productive infection, due to an elongation defect. This insight defines a fundamental role of ICP22 in HSV-1 infection and elucidates the involvement of cellular factors in HSV-1 transcription.
The Primary Enveloped Virion of Herpes Simplex Virus 1: Its Role in Nuclear Egress
Authors: Newcomb William W. , Fontana Juan , Winkler Dennis C. , Cheng Naiqian , Heymann J. Bernard , Steven Alasdair C.
Published: June 2017

Many viruses migrate between different cellular compartments for successive stages of assembly. The HSV-1 capsid assembles in the nucleus and then transfers into the cytoplasm. First, the capsid buds through the inner nuclear membrane, becoming coated with nuclear egress complex (NEC) protein. This yields a primary enveloped virion (PEV) whose envelope fuses with the outer nuclear membrane, releasing the capsid into the cytoplasm. We investigated the associated molecular mechanisms by isolating PEVs from US3-null-infected cells and imaging them by cryo-electron microscopy and tomography. (pUS3 is a viral protein kinase in whose absence PEVs accumulate in the perinuclear space.) Unlike mature extracellular virions, PEVs have very few glycoprotein spikes. PEVs are ~20% smaller than mature virions, and the little space available between the capsid and the NEC layer suggests that most tegument proteins are acquired later in the egress pathway. Previous studies have proposed that NEC is organized as hexamers in honeycomb arrays in PEVs, but we find arrays of heptameric rings in extracts from US3-null-infected cells. In a PEV, NEC contacts the capsid predominantly via the pUL17/pUL25 complexes which are located close to the capsid vertices. Finally, the NEC layer dissociates from the capsid as it leaves the nucleus, possibly in response to pUS3-mediated phosphorylation. Overall, nuclear egress emerges as a process driven by a program of multiple weak interactions.

IMPORTANCE
On its maturation pathway, the newly formed HSV-1 nucleocapsid must traverse the nuclear envelope, while respecting the integrity of that barrier. Nucleocapsids (125 nm in diameter) are too large to pass through the nuclear pore complexes that conduct most nucleocytoplasmic traffic. It is now widely accepted that the process involves envelopment/de-envelopment of a key intermediate—the primary enveloped virion. In wild-type infections, PEVs are short-lived, which has impeded study. Using a mutant that accumulates PEVs in the perinuclear space, we were able to isolate PEVs in sufficient quantity for structural analysis by cryo-electron microscopy and tomography. The findings not only elucidate the maturation pathway of an important human pathogen but also have implications for cellular processes that involve the trafficking of large macromolecular complexes.
The addition of a tension night splint to a structured home rehabilitation programme in patients with chronic plantar fasciitis does not lead to significant additional benefits in either pain, function or flexibility: a single-blinded randomised controlled trial
Authors: Wheeler Patrick C
Published: June 2017

Objective

To identify any improvements in pain or function in patients with chronic plantar fasciitis following the use of a tension night splint (TNS).

Methods

Single-blinded randomised controlled trial, with participants split evenly between intervention group (TNS + home exercise programme/HEP) and control group (HEP only). Follow-up at 3 months, with interim data at 6 weeks.

Results

40 patients recruited. Mean age 52.1 years, 33% male, mean body mass index 30.8 kg/m2, mean duration of symptoms of 25 months. Improvement in self-reported ‘average pain' in the intervention group from 6.8/10 at baseline to 5.6/10 at 6 weeks, and 5.3/10 at 3 months (both clinically and statistically significant at both time points), compared with control group of 7.1/10 at baseline to 6.2/10 at 6 weeks and 5.6/10 at 3 months (significant only at 3 months). Improvements in self-reported ‘worst pain', ‘pain walking' and ‘pain first thing in the morning' in both groups at all time periods. Improvements were seen in revised Foot Function Index at all time points in both groups, but limited changes seen in flexibility and no significant changes in anxiety or depression Hospital Anxiety and Depression Scale domains or sleep quality in either group. However, no differences were seen between the outcomes seen in the two groups for the majority of the measures studied.

Conclusions

Improvements in pain and some functional measures seen in both groups, with few, if any, differences seen in outcomes between the intervention group compared with the control group. However, ongoing pain symptoms were reported in both groups, suggesting that ‘help' rather than ‘cure' was obtained for the majority. There is a possibility of earlier benefit seen in the intervention group compared with the control group, but data are unclear and further work may be needed.

Trial registration number

ClinicalTrials.gov:NCT02546115; results.
Arts in science education
Authors: Izadi Dina
Published: June 2017

Combining the arts and standard curricula together can create a richer and more lasting learning experience for students who believe that learning science is boring in classes. It is suggested that study of the arts should be accepted as an essential part of achieving success in work. To this end, the most important action will be coordinating efforts of scholars from various areas to allow arts education for science students to become an evidence-based field. It is our contention that while the sciences seek to find answers to the most fundamental questions about our physical world, we need to find a place for the arts within the curriculum and within the process of scientific investigation. The arts should be applied in science education in a manner that considers the culture of each community. Those who are actively engaged in arts should be able to better manage their scientific projects and be able to better communicate and think. The main goal of arts in science education is to give students the opportunity to express their thoughts and feelings in the context of their different cultures and also to understand science through the lens of their creative activity in arts.
Non-equilibrium modeling of the Fe XVII 3C/3D ratio for an intense X-ray free electron laser
Authors: Li Y. , Fogle M. , Loch S.D. , Ballance C.P. , Fontes C.J.
Published: June 2017

We present a review of two methods used to model recent LCLS experimental results for the 3C/3D line intensity ratio of Fe XVII (S. Bernitt, et al. Nature, 492, 225 (2012)), the time-dependent collisional-radiative method and the density matrix approach. These are described and applied to a two-level atomic system excited by an X-ray free electron laser. A range of pulse parameters is explored and the effects on the predicted Fe XVII 3C and 3D line intensity ratio are calculated. To investigate the behavior of the predicted line intensity ratio, a particular pair of A-values for the 3C and 3D transitions was chosen (2.22 × 1013 s−1 and 6.02 × 1012 s−1 for 3C and 3D, respectively), but our conclusions are independent of the precise values. We also reaffirm the conclusions from Oreshkina et al. (N.S. Oreshkina, et al. Phys. Rev. Lett. 113, 143001 (2014); Ibid. J. Phys. B, 49, 094003 (2015)): the nonlinear effects in the density matrix are important and the reduction in the Fe XVII 3C/3D line intensity ratio is sensitive to the laser pulse parameters, namely, pulse duration, pulse intensity, and laser bandwidth. It is also shown that for both models the lowering of the 3C/3D line intensity ratio below the expected time-independent oscillator strength ratio has a significant contribution due to its emission from the plasma after the laser pulse has left the plasma volume. Laser intensities above ∼1 × 1012 W/cm2 are required for a reduction in the 3C/3D line intensity ratio below the expected time-independent oscillator strength ratio.
Black hole shadows in fourth-order conformal Weyl gravity
Authors: Mureika Jonas R. , Varieschi Gabriele U.
Published: June 2017

We calculate the characteristics of the “black hole shadow” for a rotating, neutral black hole in fourth-order conformal Weyl gravity. It is shown that the morphology is not significantly affected by the underlying framework, except for very large masses. Conformal gravity black hole shadows would also significantly differ from their general relativistic counterparts if the values of the main conformal gravity parameters, γ and κ, were increased by several orders of magnitude. Such increased values for γ and κ are currently ruled out by gravitational phenomenology. Therefore, it is unlikely that these differences in black hole shadows will be detected in future observations, carried out by the Event Horizon Telescope or other such experiments.
The influence of excitation number of photon-added coherent state field on the entanglement swapping process
Authors: Soltani M. , Tavassoly M. K. , Pakniat R.
Published: June 2017

In this paper, we outline a scheme for the entanglement swapping procedure based on cavity quantum electrodynamics using the Jaynes–Cummings model consisting of the coherent and photon-added coherent states. In particular, utilizing the photon-added coherent states ([Formula: see text][Formula: see text][Formula: see text][Formula: see text], where [Formula: see text] is the Glauber coherent state) in the scheme, enables us to investigate the effect of [Formula: see text], i.e., the number of excitations corresponding to the photon-added coherent field on the entanglement swapping process. In the scheme, two two-level atoms [Formula: see text] and [Formula: see text] are initially entangled together, and distinctly two exploited cavity fields [Formula: see text] and [Formula: see text] are prepared in an entangled state (a combination of coherent and photon-added coherent states). Interacting the atom [Formula: see text] with field [Formula: see text] (via the Jaynes–Cummings model) and then making detection on them, transfers the entanglement from the two atoms [Formula: see text], [Formula: see text] and the two fields [Formula: see text], [Formula: see text] to the atom-field “[Formula: see text]-[Formula: see text]”, i.e., entanglement swapping occurs. In the continuation, we pay our attention to the evaluation of the fidelity of the swapped entangled state relative to a suitable maximally entangled state, success probability of the performed detections and linear entropy as the degree of entanglement of the swapped entangled state. It is demonstrated that, an increase in the number of excitations, [Formula: see text], leads to the increment of fidelity as well as the amount of entanglement. According to our numerical results, the maximum values of fidelity (linear entropy) 0.98 (0.46) is obtained for [Formula: see text], however, the maximum value of success probability does not significantly change by increasing [Formula: see text].
Effect of current density on the deposit stress in gold electroplating
Authors: Hou Shuangyue , Xiong Ying , Chen Shan , Chen Xiangyu , Xiong Penghui , Tian Yangchao , Liu Gang
Published: June 2017

As the key components of grating-based X-ray phase contrast imaging, absorption gratings are essential to be fabricated. In fact, the internal stress is one of the critical issues for the application of the electroplated gold deposit as the absorption metal for absorption gratings. It is common that high internal stress levels can cause the deposit cracking, blistering and peeling away from the substrate material. This study investigates the effect of current density on the internal stress by the bent strip method. The surface morphologies of gold deposits are examined using scanning electron microscopy (SEM) and the crystal structure of the electroplated deposit is analyzed by X-ray diffraction (XRD). The change of current density reverses the internal stress of the deposits from compressive to tensile. The value of deposit stress can be near zero by optimizing the current density.
Bäcklund transformations of Zn-sine-Gordon systems
Authors: Yang Xueping , Li Chuanzhong
Published: June 2017

In this paper, from the algebraic reductions from the Lie algebra [Formula: see text] to its commutative subalgebra [Formula: see text], we construct the general [Formula: see text]-sine-Gordon and [Formula: see text]-sinh-Gordon systems which contain many multi-component sine-Gordon type and sinh-Gordon type equations. Meanwhile, we give the Bäcklund transformations of the [Formula: see text]-sine-Gordon and [Formula: see text]-sinh-Gordon equations which can generate new solutions from seed solutions. To see the [Formula: see text]-systems clearly, we consider the [Formula: see text]-sine-Gordon and [Formula: see text]-sine-Gordon equations explicitly including their Bäcklund transformations, the nonlinear superposition formula and Lax pairs.
Phase stability, mechanical and optoelectronic properties of two novel phases of AlN
Authors: Yang Ruike , Zhu Chuanshuai , Wei Qun , Du Zheng
Published: June 2017

Two novel aluminum nitride (which is bct-AlN at ambient pressure, and h-AlN at higher pressure) were predicted using first-principles calculations. The mechanical and phonon dispersion results indicate that bct-AlN is mechanically and dynamically stable at zero pressure, h-AlN phase can be stabilized by increasing pressure and it is mechanically and dynamically stable at 10 GPa. bct-AlN is more favorable than rs-AlN in thermodynamics at ambient pressure. Our calculated band gap of bct-AlN is 5.85 eV. It can be used as semiconductor device and optoelectronic device due to its inherent wide direct band gap. For bct-AlN, the shortest Al–N bond length is 1.8476 Å and its bond order index is 1.28, which shows that strong covalent bonds are formed between Al atoms and N atoms. Moreover, the anisotropy of Young’s modulus and optical properties can be noticed obviously for bct-AlN.
Recaptured Image Forensics Algorithm Based on Multi-Resolution Wavelet Transformation and Noise Analysis
Authors: Sun Yanjun , Shen Xuanjing , Lv Yingda , Liu Changming
Published: June 2017

With the rapid development of digital cameras and smart phones, the image identification system in current times will be of a great impact. This will cause the form of image information to increase serious security issues. Especially, the emergence of the recaptured image makes conventional digital image forensics algorithm invalid. Therefore, a new image forensics algorithm is urgently needed to identify the recaptured image. In this paper, a new recaptured image identifying algorithm is put forward based on wavelet transformation and noise analysis by analyzing the differences between the real and recaptured images generated in the imaging process. First, the proposed algorithm extracts mean value, variance and skewness as wavelet characteristic from the high-frequency images and low-frequency images by wavelet transformation. Meanwhile, the proposed algorithm analyzes the noise image by means of local binary pattern to extract noise characteristic. Finally, the support vector machine is applied to classify the recaptured image with wavelet characteristics and noise characteristics. The results show the presented method can not only identify the recaptured image obtained from different media but also have better identification rate, and the dimension of the characteristic vector is also lower than those obtained by other algorithms.
Nonlinear Structural Damage Detection Based on Adaptive Volterra Filter Model
Authors: Prawin J. , Rao A. Rama Mohan
Published: June 2017

The majority of the existing damage diagnostic techniques are based on linear models. Changes in the state of the dynamics of these models, before and after damage in the structure based on the vibration measurements, are popularly used as damage indicators. However, the system may initially behave linearly and subsequently exhibit nonlinearity due to the incipience of damage. Breathing cracks that exhibit bilinear behavior are one such example of the damage induced due to nonlinearity. Further many real world structures even in their undamaged state are nonlinear. Hence, in this paper, we present a nonlinear damage detection technique based on the adaptive Volterra filter using the nonlinear time history response. Three damage indices based on the adaptive Volterra filter are proposed and their sensitiveness to damage and noise is assessed through two numerically simulated examples. Numerical investigations demonstrate the effectiveness of the adaptive Volterra filter model to detect damage in nonlinear structures even with measurement noise.
A Meshfree Approach for Transient Heat Conduction Analysis of Nonlinear Functionally Graded Materials
Authors: Hidayat Mas Irfan P. , Ariwahjoedi Bambang , Parman Setyamartana , Irawan Sonny
Published: June 2017

In this paper, an alternative meshfree approach is presented for transient heat conduction analysis of nonlinear functionally graded materials (FGMs). The main idea behind the introduced approach is to use collocation in local domains containing of sets of regular or scattered nodes and approximating the solution by B-spline basis functions. It combines the favorable properties of B-spline basis functions in having arbitrary degree for better resolution of solution, partition of unity and the Kronecker delta properties with low computational effort of collocation. The method is called as local B-spline collocation method. It is mathematically simple, efficient to program and truly meshless. The method is applied for analyzing transient heat conduction in a wide range of FGMs with various material gradation models, in both 2D and 3D domains. The results obtained agree well with those computed by analytical solution and other well-known methods, confirming the suitability and efficacy of the presented scheme.
Torsion-free G2-structures with identical Riemannian metric
Authors: Lin Christopher
Published: June 2017

Based on a general formula due to Bryant, we work out the topological structure of the space of torsion-free [Formula: see text]-structures generating the same associated Riemannian metric on a compact [Formula: see text]-manifold. We also identify a corresponding Lie group-theoretic structure of the space. These observations are then used to describe the moduli space of torsion-free [Formula: see text]-structures in certain cases — by way of covering spaces.
Synthesis of graphene nanoflakes by grinding natural graphite together with NaCl in a planetary ball mill
Authors: Alinejad Babak , Mahmoodi Korosh
Published: June 2017

Natural graphite is a soft material that conventional milling methods fail to grind into nanoparticles. We found that adding NaCl into graphite during milling allows obtaining graphene nanoflakes of about 50[Formula: see text][Formula: see text][Formula: see text]200[Formula: see text]nm2 as evidenced by Transmission Electron Microscope (TEM). NaCl particles are substantially brittle and harder than graphite, serving as milling agents by both helping to chop graphite into smaller pieces and preventing graphite particles from agglomeration. After milling, NaCl can be easily washed away by water. Probable mechanism for exfoliation of graphene during the modified ball milling may be explained by NaCl and graphene slipping or sliding against and over each other, exfoliating the graphene particles into thin layers.
4D Visual Delivery of Big Climate Data: A Fast Web Database Application System
Authors: Pierret Julien , Shen Samuel S. P.
Published: June 2017

This paper develops a web database application to make space-time 4D visual delivery (4DVD) of big climate data. The delivery system shows climate data in a 4D space-time box and allows users to visualize the data. Users can zoom in or out to help identify desired information for particular locations. Data can then be downloaded for the spatial maps and historical climate time series of a given location after the maps and time series are identified to be useful. These functions enable a user to quickly reach the core interested features without downloading the entire dataset in advance, which saves both time and storage space. The 4DVD system has many graphical display options such as displaying data on a round globe or on a 2D map with detailed background topographic images. It can animate maps and show time series. The combination of these features makes the system a convenient and attractive multimedia tool for classrooms, museums, and households, in addition to climate research scientists, industrial applicants, and policy makers. To demonstrate the 4DVD’s usage, several application examples are included in this paper, such as the La Nina’s influence on land temperature.
New insights into the unexploited reservoir potential of the Mid North Sea High (UKCS quadrants 35–38 and 41–43): a newly described intra-Zechstein sulphate–carbonate platform complex
Authors: Patruno Stefano , Reid William , Jackson Christopher A-L. , Davies Chris
Published: June 2017

The Mid North Sea High (MNSH) is located on the UKCS in quadrants 35–38 and 41–43. It is a large structural high that is flanked by the mature hydrocarbon provinces of the Central North Sea (CNS) to the NE and the Southern North Sea (SNS) to the SE. In the MNSH region, the source and reservoir intervals that characterize the SNS (Westphalian, Lower Permian) are absent and therefore the area is relatively underexplored compared to the SNS Basin (
c
. one well per 1000 km
2
). Nevertheless, two discoveries in Dinantian reservoirs (Breagh and Crosgan) prove that a working petroleum system is present, potentially charged either via lateral migration from the SNS or from within the lower Carboniferous itself. Additionally, gas was found in the Z2 carbonate (lower Zechstein Group) in Crosgan, with numerous other wells in the area reporting hydrocarbon shows in this unit. The results of the interpretation of recently acquired 2D and 3D seismic reflection datasets over parts of UKCS quadrants 36, 37 and 42 are presented and provide insight into both the geology and prospectivity of this frontier area.

This study suggests that intra-Zechstein clinoform foresets represent an attractive, hitherto overlooked, exploration target. The Zechstein Group sits on a major unconformity, probably reflecting Variscan-related inversion and structural uplift. Below it, fault blocks and faulted folds occur, containing pre-Westphalian Carboniferous and Devonian sediments, both of which contain potential reservoirs. In the lower Zechstein, a large build-up is observed, covering a total area of 2284 km
2
. This is bounded on its margins by seismically defined clinoforms, with maximum thicknesses of 0.12 s two-way time (
c.
240–330 m). This rigid, near-tabular unit is clearly distinguished from the overlying deformed upper Zechstein evaporites. In map-view, a series of embayments and promontories are observed at the build-up margins. Borehole data and comparisons with nearby discoveries (e.g. Crosgan) suggest this build-up to represent a Z1–Z2 sulphate–carbonate platform, capped by a minor Z3 carbonate platform. Interpreted smaller pinnacle build-ups are observed away from the main bank. The seismic character, geometry, size and inferred composition of this newly described Zechstein platform are similar to those of platforms hosting notable hydrocarbon discoveries in other parts of the Southern Permian Basin. The closest of these discoveries to the study area is Crosgan, which is characterized by the Z2 carbonate clinothem (Hauptdolomit Formation) as a proven reservoir.
Comparative numerical modelling of a debris-flow fan in the Eastern Italian Alps
Authors: Deganutti Andrea M. , Tecca Pia R. , Nigro Giuseppe
Published: June 2017

Knowledge of rheology can reduce damage caused by debris flows, providing a means to delineate hazard-prone areas and to estimate the dangerous effects of these phenomena. The application of numerical models of debris-flow propagation and deposition for hazard prediction requires detailed topographical, hydrological and rheological data, which are not always available. The large Rivoli Bianchi Fan on the Eastern Italian Alps is mainly built from sediment transported by debris flows along the Citate Torrent and its tributaries. We compared the results of numerical simulations performed with two different single-phase, non-Newtonian, two-dimensional models, FLO-2D and IDRA2D-DF, to test their reliability in simulating the behaviour of debris flows on alluvial fans. Data from field topographic surveys and from rain gauges were used as input for the boundary conditions, referring to the Rivoli Bianchi Fan as an example location. The commercial FLO-2D model creates a more accurate representation of the hazard-prone zone in terms of flooded area, but the results in terms of runout distances and deposit thickness are similar to those obtained through the open-source IDRA2D-DF. Parameters obtained through back analysis with both models can be cautiously applied to predict hazard in areas of similar geology, morphology and climate.
A deep subglacial embayment adjacent to the grounding line of Institute Ice Stream, West Antarctica
Authors: Jeofry Hafeez , Ross Neil , Corr Hugh F. J. , Li Jilu , Gogineni Prasad , Siegert Martin J.
Published: June 2017

The Institute Ice Stream (IIS) in West Antarctica may be increasingly vulnerable to melting at the grounding line through modifications in ocean circulation. Understanding such change requires knowledge of grounding-line boundary conditions, including the topography on which it rests. Here, we discuss evidence from new radio-echo sounding (RES) data on the subglacial topography adjacent to the grounding line of the IIS. In doing so, we reveal a previously unknown subglacial embayment immediately inland of the IIS grounding zone which is not represented in the Bedmap2 compilation. We discuss whether there is an open-water connection between the embayment and the ice-shelf cavity. The exact location of the grounding line over the embayment has been the subject of considerable uncertainty, with several positions being proposed recently. From our compilation of data, we are able to explain which of these grounding lines is most likely and, in doing so, highlight the need for accurate bed topography in conjunction with satellite observations to fully comprehend ice-sheet processes in this region and other vulnerable locations at the grounded margin of Antarctica.
Identity: the killer app of crowdfunded open hardware
Authors: Lifton Joshua
Published: June 2017

In the next 20 years, the notion of a secure, verifiable identity will drive the adoption of crowdfunded open hardware.