bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and performance of high-temperature furnace and cell holder for in situ spectroscopic, electrochemical, and radiolytic investigations of molten salts
Authors: Phillips William C. , Gakhar Ruchi , Horne Gregory P. , Layne Bobby , Iwamatsu Kazuhiro , Ramos-Ballesteros Alejandro , Shaltry Michael R. , LaVerne Jay A. , Pimblott Simon M. , Wishart James F.
Published: August 2020

To facilitate the development of molten salt reactor technologies, a fundamental understanding of the physical and chemical properties of molten salts under the combined conditions of high temperature and intense radiation fields is necessary. Optical spectroscopic (UV–Vis–near IR) and electrochemical techniques are powerful analytical tools to probe molecular structure, speciation, thermodynamics, and kinetics of solution dynamics. Here, we report the design and fabrication of three custom-made apparatus: (i) a multi-port spectroelectrochemical furnace equipped with optical spectroscopic and electrochemical instrumentation, (ii) a high-temperature cell holder for time-resolved optical detection of radiolytic transients in molten salts, and (iii) a miniaturized spectroscopy furnace for the investigation of steady-state electron beam effects on molten salt speciation and composition by optical spectroscopy. Initial results obtained with the spectroelectrochemical furnace (i) and high-temperature cell holder (ii) are reported.
Model of neuroendocrine hormone release might lead to improved hormone delivery systems
Authors: Mandel Savannah
Published: August 2020

A mathematical model to understand the pulsatility of neuroendocrine hormone release may help the development of pulsatile drug delivery systems.
The discrete fractional duffing system: Chaos, 0–1 test, C complexity, entropy, and control
Authors: Ouannas Adel , Khennaoui Amina-Aicha , Momani Shaher , Pham Viet-Thanh
Published: August 2020

In this paper, we study the dynamics and control of a Caputo fractional difference form of the Duffing map. We use phase plots, bifurcation diagrams, and Lyapunov exponents to establish the existence of chaos over a wide range of fractional orders and examine the nature of the dynamics. Also, we present the 0–1 test to detect chaos and C0 complexity, which is an alternative nonlinear statistical measure that can quantify the regularity of a time series. In addition, we measure the approximate entropy to see the performance of our numerical results. Through phase plots and bifurcation diagrams, it is shown that the proposed fractional map exhibits a range of different dynamical behaviors including chaos and coexisting attractors. A one-dimensional feedback stabilization controller is proposed. The asymptotic convergence of the proposed controller is established by means of the stability theory of linear fractional order discrete-time systems. Simulation results have been carried out to illustrate the findings of the study.
An integrate-and-fire model for pulsatility in the neuroendocrine system
Authors: Churilov Alexander N. , Milton John , Salakhova Elvira R.
Published: August 2020

A model for pulsatility in neuroendocrine regulation is proposed which combines Goodwin-type feedback control with impulsive input from neurons located in the hypothalamus. The impulsive neural input is modeled using an integrate-and-fire mechanism; namely, inputs are generated only when the membrane potential crosses a threshold, after which it is reset to baseline. The resultant model takes the form of a functional-differential equation with continuous and impulsive components. Despite the impulsive nature of the inputs, realistic hormone profiles are generated, including ultradian and circadian rhythms, pulsatile secretory patterns, and even chaotic dynamics.
Influence of stacking disorder on cross-plane thermal transport properties in TMPS3 (TM = Mn, Ni, Fe)
Authors: Ju Hwiin , Jeong Do-Gyeom , Choi Young-Gwan , Son Suhan , Jung Wan-Gil , Jung Myung-Chul , Kang Soonmin , Han Myung Joon , Kim Bong-Joong , Park Je-Geun , Lee Jong Seok
Published: August 2020

We investigated the thermal transport properties of magnetic van der Waals materials, TMPS3 (TM = Mn, Ni, and Fe), using the time-domain thermoreflectance technique. We determined the cross-plane thermal conductivity, which turns out to be relatively low, i.e., about 1 W m−1 K−1 for all TMPS3 investigated. When compared with previous results of graphite and transition metal dichalcogenides (TMDs), thermal conductivity becomes smaller as it goes from graphite to TMDs to TMPS3, and the difference is larger at low temperature, e.g., around 50 K. From the Callaway model analysis, we could attribute the large thermal conductivity reduction for TMPS3, particularly at low temperature, to the phonon scattering from the boundary. We actually confirmed the existence of the large population of the stacking faults with the cross-sectional transmission electron microscopy image of MnPS3. This suggests that intrinsic or extrinsic stacking faults formed in van der Waals materials and their heterostructures can play an important role in reducing the cross-plane thermal conductivity as a source of the boundary scattering.
Local bifurcation structure of a bouncing ball system with a piecewise polynomial function for table displacement
Authors: Okishio Yudai , Ito Hiroaki , Kitahata Hiroyuki
Published: August 2020

The system in which a small rigid ball is bouncing repeatedly on a heavy flat table vibrating vertically, so-called the bouncing ball system, has been widely studied. Under the assumption that the table is vibrating with a piecewise polynomial function of time, the bifurcation diagram changes qualitatively depending on the order of the polynomial function. We elucidate the mechanism of the difference in the bifurcation diagrams by focusing on the two-period solution. In addition, we derive the approximate curve of the branch close to the period-doubling bifurcation point in the case of the piecewise cubic function of time for the table vibration. We also performed numerical calculation, and we demonstrate that the approximations well reproduce the numerical results.
Investigation of cavitation and vapor shedding mechanisms in a Venturi nozzle
Authors: Brunhart Maxwell , Soteriou Celia , Gavaises Manolis , Karathanassis Ioannis , Koukouvinis Phoevos , Jahangir Saad , Poelma Christian
Published: August 2020

Cavitating flow dynamics are investigated in an axisymmetric converging–diverging Venturi nozzle. Computational Fluid Dynamics (CFD) results are compared with those from previous experiments. New analysis performed on the quantitative results from both datasets reveals a coherent trend and shows that the simulations and experiments agree well. The CFD results have confirmed the interpretation of the high-speed images of the Venturi flow, which indicated that there are two vapor shedding mechanisms that exist under different running conditions: re-entrant jet and condensation shock. Moreover, they provide further details of the flow mechanisms that cannot be extracted from the experiments. For the first time with this cavitating Venturi nozzle, the re-entrant jet shedding mechanism is reliably achieved in CFD simulations. The condensation shock shedding mechanism is also confirmed, and details of the process are presented. These CFD results compare well with the experimental shadowgraphs, space–time plots, and time-averaged reconstructed computed tomography slices of vapor fraction.
Uniform asymptotic expansion of Legendre functions
Authors: Bakaleinikov Leonid , Silbergleit Alexander
Published: August 2020

We find the large number asymptotics of the Legendre functions Pn(cos θ) and Qn(cos θ) uniform in 0 ≤ θ ≤ π by reducing the procedure to regular perturbations. The corresponding results for the associated functions Pnm(cos⁡θ) and Qnm(cos⁡θ) are also discussed.
Magnetocaloric effect manipulated through interchain exchange coupling in nanochain arrays
Authors: Hao Fei , Hu Yong
Published: August 2020

Magnetocaloric effect in nanochain arrays is numerically studied when interchain exchange couplings (Jinter) are taken into account. With increasing Jinter, moment-reorientation phase transition temperature driven by anisotropy is enhanced and magnetic ordering phase transitions governed by Jinter may happen independently at higher temperatures, resulting in temperature induced multiple phase transitions that separate distinct dynamic properties of magnetization. As a result, maximum values of positive and negative magnetic entropy change (ΔSM) are both close to 0.4 J kg−1 K−1, with their peak temperature 100–300 K and 250–550 K, depending on Jinter, and a large refrigeration capacity is obtained due to a wide working temperature range of ΔSM. In nanostructures, the proper magnetic viscosity arising from Jinter makes materials become semi-bulk, i.e., in which ΔSM maximum value and peak temperature are highly enhanced, associated with a considerably wide working temperature range.
Systematics of the Peripatopsis clavigera species complex (Onychophora : Peripatopsidae) reveals cryptic cladogenic patterning, with the description of five new species
Authors: Barnes Aaron , Reiss Till , Daniels Savel R.
Published: August 2020

During the present study, DNA sequence data, gross morphology and scanning electron microscopy (SEM) were used to examine cryptic species boundaries in the velvet worm, Peripatopsis clavigera species complex, from the southern Cape Afrotemperate forest belt in South Africa. Sequence data were generated for the mitochondrial COI and the nuclear 18S rRNA loci and phylogenetically analysed using both a Bayesian inference and a maximum-likelihood approach. Both the COI data and the combined DNA sequence topology (COI+18S) revealed the presence of five clades within the Peripatopsis clavigera species complex, and revealed that specimens from Tulbagh were distantly related and represented a sixth clade. The evolutionary distinction of the five clades was corroborated to varying degrees by the four species-delimitation methods (ABGD, PTP, GMYC and STACEY); however, both the gross morphological data and the SEM provided limited diagnostic differences between the five clades. Furthermore, the COI haplotype network and phylogeographic analyses provided evidence of genetic isolation between lineages that are currently syntopic. The distribution of genealogically exclusive and widespread maternal lineages was atypical among velvet worms and did not reflect the general trend of genetic and geographical isolation. Instead, lineages exhibited admixture among localities, a result most likely due to fluctuations in climatic conditions affecting the southern Cape Afrotemperate forest during the Pliocene–Pleistocene period as evident from our divergence time estimations. Four novel, narrow-range endemic species – P. ferox, sp. nov., P. mellaria, sp. nov., P. edenensis, sp. nov. and P. mira, sp. nov. – are described within the P. clavigera species complex, whereas the Tulbagh specimens are described as P. tulbaghensis, sp. nov. Collectively, these results demonstrate that Peripatopsis likely contains several undescribed species.
Modelling the abundance and productivity distribution to understand the habitat–species relationship: the guanaco (Lama guanicoe) case study
Authors: Flores Celina E. , Bellis Laura M. , Adrián Schiavini
Published: August 2020

Abstract
ContextThe conservation of large wild herbivores presents a challenge posed by the fact that their broad habitat requirements overlap with various human activities. Elucidating the factors that explain their distribution patterns provides us with a better understanding of habitat–species relationships and facilitates the design of effective management policies.
AimsIdentify the natural (forage availability, weather) and anthropogenic (hunting, interspecific competition) factors that explain the abundance and productivity distribution of the guanaco. Estimate guanaco abundance and productivity and describe their distribution.
MethodsWe estimated the abundance and productivity of guanaco by using aerial surveys during the breeding and non-breeding season of two consecutive years, following the strip-transect methodology; we then modelled these as a function of environmental factors by means of density surface models.
Key resultsThe highest abundance and productivity of guanaco occurred mostly where mesic grassland was dominant. Guanaco abundance presented three hotspots on the basis of geographic location, and family groups were more productive at low to intermediate livestock level. Abundance was significantly higher in the breeding season for both years (5614 and 14092 individuals) than in the non-breeding season (2922 and 6926 individuals), and it was higher in 2015 than in 2014. Productivity was higher in 2015 than in 2014 (0.54 and 0.46 calves per adult respectively).
ConclusionsGuanaco responded to forage availability, occupying zones with low to intermediate food availability in the breeding season, and those with the highest availability in the non-breeding season. This could be due to interspecific competition between livestock and guanaco family groups. We propose that the overall guanaco response could also be explained by social structure or by unassessed factors such as predation risk by feral dogs.
ImplicationsThe guanaco could compensate for the use of habitats with a lower food availability during the breeding season by using better-quality habitats during the non-breeding season.
TheαβTCR mechanosensor exploits dynamic ectodomain allostery to optimize its ligand recognition site
Authors: Hwang Wonmuk , Mallis Robert J. , Lang Matthew J. , Reinherz Ellis L.
Published: August 2020

Significance

αβT cell receptors (TCRs) recognize antigenic peptide bound to major histocompatibility complex (pMHC) molecules with exquisite sensitivity. An emerging concept is thatαβTCR functions as a mechanosensor whereby the complex between its ligand-binding TCRαβheterodimer and pMHC increases the bond lifetime under physiological-level force, the so-called catch bond. This study reveals the physical mechanism for catch bond behavior. Multiple layers of control are identified, including the dynamics of interfacial contacts, and the motion and geometry of the four subdomains of TCRαβ, all of which are influenced by the load applied to the TCRαβ-pMHC complex. These findings shall contribute to understanding the TCR mechanobiology and shall assist with design of future TCR-based immunotherapies.
The roles of long-range proton-coupled electron transfer in the directionality and efficiency of [FeFe]-hydrogenases
Authors: Lampret Oliver , Duan Jifu , Hofmann Eckhard , Winkler Martin , Armstrong Fraser A. , Happe Thomas
Published: August 2020

Significance

Activation of hydrogen in biology is achieved by enzymes rivalling the platinum metals in catalytic activity. Attached to an electrode, hydrogenases display electrocatalytic reversibility—just the tiniest potential bias from the equilibrium value drives oxidation or production of H
2
at significant rates. Hydrogenases activate H
2
heterolytically; hence, reversibility, an extreme marker for evolved efficiency, is expected to depend on electron and proton transfer processes occurring in concert. Experiments in which the long-range proton-transfer pathway in two [FeFe]-hydrogenases has been mildly disrupted without affecting the electron transfer pathway show that electrocatalytic reversibility fades as electron and proton transfers become temporally decoupled. These subtlest of observations demonstrate how evolution responded to the need for concerted electron–proton transfer in optimizing catalytic efficiency.
The use of machine learning in digital processing of satellite images applied to coffee crop
Authors: da Jonathan , de Marcelo
Published: August 2020

Remote sensing can be used to monitor and estimate, with reasonable correct answers, the yield, plant health, and coffee nutrition. Satellite-coupled sensors can obtain information about the spectral signature of the crop, on a time scale, in order to monitor and detect phenological changes. However, the accumulation of data obtained by orbital sensors makes it difficult to understand the relationship between the aspects of coffee. Thus, machine learning can perform data mining and meet the spectral signature patterns that constitute coffee behavior. This literature review sought the survey of research that used machine learning tools applied in digital image processing from satellites for coffee crop monitoring.
Organisers’ knowledge and opinion towards the flemish legislation of noise exposure at music festivals
Authors: Keppler Hannah , Heyse Julie , Degeest Sofie , Vinck Bart
Published: August 2020

Purpose

During leisure-time activities, young people expose themselves regularly to sound levels that may hamper the auditory system. In Flanders (Belgium), there is a noise legislation for indoor and outdoor music venues whereby a distinction is made into three categories of maximum allowable sound levels and accompanying measures. The aim of the current study was to investigate the knowledge and personal opinion of organisers of music festivals regarding this noise legislation.

Methods

An online questionnaire was answered by 36 music festival organisers.

Results

In general, the categories of (non-)classified facilities with maximum allowable sound levels and accompanying measures were not well known by the respondents. Most respondents were moderately prepared to apply the noise legislation at music festivals and most of them indicated the noise legislation is moderately financially feasible and very logistically feasible. The correctness of the answers to some knowledge questions was significantly different between the degree of being informed, the perception of intelligibility of the received information, and the financial and logistical feasibility of the noise legislation.

Conclusions

Compliance with the noise legislation at music venues should be further investigated, along with a refreshing of the information that was made available to increase knowledge and awareness of the risks of noise exposure among organisers of music events.
Lack of association between contralateral inhibition of otoacoustic emissions and vowel formant discrimination in noise
Authors: Mertes Ian B. , Johnson Kristin M.
Published: August 2020

Purpose

The medial olivocochlear (MOC) reflex enhances neural encoding of signals in noise, and measurement of its function may hold clinical utility. Previous research on how the reflex aids speech-in-noise perception has been equivocal. Motivated by animal work, we examined associations between MOC reflex activity and formant discrimination in noise in humans to better understand how the MOC reflex contributes to audition. We hypothesised that participants with stronger MOC reflex activity would have better formant discrimination in noise abilities.

Method

Twenty-six normal-hearing listeners met all inclusion and exclusion criteria (mean age = 21.5 years), with data from 25 participants included in the final analysis. Transient-evoked otoacoustic emissions (TEOAEs) were measured in right ears. MOC reflex activity was assessed using a contralateral inhibition paradigm in which the change in TEOAE amplitude without versus with a contralateral MOC reflex elicitor was computed. Formant discrimination thresholds for a synthetic vowel /[Latin Small Letter Open E]/ were obtained in right ears using a two-alternative forced-choice procedure that adaptively varied the second formant frequency. Discrimination thresholds were obtained at three signal-to-noise ratios (SNRs).

Results

TEOAE amplitudes were significantly reduced in the presence of the reflex elicitor (p < .05). Discrimination thresholds decreased significantly with increasing SNR (p < .05 in all cases). No significant correlations were found between contralateral inhibition measures and discrimination thresholds at any SNR (p > .05 in all cases).

Conclusion

Contrary to hypothesis, no significant associations were found between contralateral inhibition and formant discrimination in noise performance. It is possible that the MOC reflex contributes to formant discrimination but not in a monotonic fashion. Future work should consider investigating how the MOC reflex contributes to other perceptual properties to better characterise the functional relevance of the MOC reflex.
RSSs set the odds for exclusion
Authors: Krangel Michael S.
Published: August 2020

In this issue of JEM, Wu et al. (https://doi.org/10.1084/jem.20200412) provide new insights into allelic exclusion. They demonstrate that Vβ-to-DβJβ rearrangement occurs stochastically on two competing Tcrb alleles, with suboptimal Vβ recombination signal sequences limiting synchronous rearrangements and essential for allelic exclusion.
Neutralizing hepatitis B
Authors: Robbiani Davide F.
Published: August 2020

Despite an effective vaccine, hepatitis B virus (HBV) remains a major public health threat since chronic infection leads to liver disease and cancer. Hehle et al. (https://doi.org/10.1084/jem.20200840) discovered human-derived antibodies that potently neutralize the virus. Will this help a cure?
Hyper-differential sensitivity analysis for inverse problems constrained by partial differential equations
Authors: Sunseri Isaac , Hart Joseph , van Bloemen Waanders Bart , Alexanderian Alen
Published: August 2020

High fidelity models used in many science and engineering applications couple multiple physical states and parameters. Inverse problems arise when a model parameter cannot be determined directly, but rather is estimated using (typically sparse and noisy) measurements of the states. The data is usually not sufficient to simultaneously inform all of the parameters. Consequently, the governing model typically contains parameters which are uncertain but must be specified for a complete model characterization necessary to invert for the parameters of interest. We refer to the combination of the additional model parameters (those which are not inverted for) and the measured data states as the ‘complementary parameters’. We seek to quantify the relative importance of these complementary parameters to the solution of the inverse problem. To address this, we present a framework based on hyper-differential sensitivity analysis (HDSA). HDSA computes the derivative of the solution of an inverse problem with respect to complementary parameters. We present a mathematical framework for HDSA in large-scale PDE-constrained inverse problems and show how HDSA can be interpreted to give insight about the inverse problem. We demonstrate the effectiveness of the method on an inverse problem by estimating a permeability field, using pressure and concentration measurements, in a porous medium flow application with uncertainty in the boundary conditions, source injection, and diffusion coefficient.
Control of phase formation of (AlxGa1 − x)2O3 thin films on c-plane Al2O3
Authors: Hassa Anna , Wouters Charlotte , Kneiß Max , Splith Daniel , Sturm Chris , von Wenckstern Holger , Albrecht Martin , Lorenz Michael , Grundmann Marius
Published: August 2020

In this paper, the growth of orthorhombic and monoclinic (Al
x
Ga1 − x
)2O3 thin films on (00.1) Al2O3 by tin-assisted pulsed laser deposition is investigated as a function of oxygen pressure p(O2) and substrate temperature

T

g

. For certain growth conditions, defined by

T

g

 ≥ 580°C and p(O2) ≤ 0.016 mbar, the orthorhombic κ-polymorph is stabilized. For

T

g

  =  540°C and p(O2) ≤ 0.016 mbar, the κ-, and the β-, as well as the spinel γ-polymorph coexist, as illustrated by XRD 2θ-ω-scans. Further employed growth parameters result in thin films with a monoclinic β-gallia structure. For all polymorphs, p(O2) and

T

g

affect the formation and desorption of volatile suboxides, and thereby the growth rate and the cation composition. For example, low oxygen pressures lead to low growth rates and enhanced Al incorporation. This facilitates the structural engineering of polymorphic, ternary (Al,Ga)2O3 via selection of the relevant process parameters. Transmission electron microscopy (TEM) studies of a κ - (Al0.13Ga0.87)2O3 thin film reveal a more complex picture compared to that derived from x-ray diffraction measurements. Furthermore, this study presents the possibility of controlling the phase formation, as well as the Al-content, of thin films based on the choice of their growth conditions.
Field-matter interactions of triangular apertures and lattices: symmetry breaking with frequency selection and polarization filtering
Authors: Kuan Wen-Hsuan
Published: August 2020

Interaction of electromagnetic (EM) waves with asymmetric triangular apertures and lattices are studied theoretically with analytical solutions and numerical simulations, where the physical symmetry and degeneracy are removed and the diffraction show distinct angular and spatial dependence on the incident EM-wave frequency. The center of the 0th-order diffraction spot for an asymmetric triangular aperture is off-axial and frequency-dependent, which is contrary to conventional symmetric apertures. For asymmetric triangular lattices, an incident wave of a given polarization state can be diffracted into several reflection and transmission modes determined by the EM frequency and lattice structures, and it is available to manipulate the number of diffraction orders as well as the EM-wave polarization and handedness. The theoretical simulations suggest that the asymmetric triangle apertures and lattices have the potential applications in angle-resolved wave scattering detectors, economic spectrum analyzers, tunable frequency filters, polarization beam splitters, and polarization controllers.
Skyrmion ground states of rapidly rotating few-fermion systems
Authors: Palm L , Grusdt F , Preiss P M
Published: August 2020

We show that ultracold fermions in an artificial magnetic field open up a new window to the physics of the spinful fractional quantum Hall (FQH) effect. We numerically study the lowest energy states of strongly interacting few-fermion systems in rapidly rotating optical microtraps. We find that skyrmion-like ground states with locally ferromagnetic, long-range spin textures emerge. To realize such states experimentally, rotating microtraps with higher-order angular momentum components may be used to prepare fermionic particles in a lowest Landau level. We find parameter regimes in which skyrmion-like ground states should be accessible in current experiments and demonstrate an adiabatic pathway for their preparation in a rapidly rotating harmonic trap. The addition of long range interactions will lead to an even richer interplay between spin textures and FQH physics.
Abrupt transition due to non-local cascade propagation in multiplex systems
Authors: Artime Oriol , De Domenico Manlio
Published: August 2020

Multilayer systems are coupled networks characterized by different contexts (layers) of interaction and have gained much attention recently due to their suitability to describe a broad spectrum of empirical complex systems. They are very fragile to percolation and first-neighbor failure propagation, but little is known about how they respond to non-local disruptions, as it occurs in failures induced by flow redistribution, for example. Acknowledging that many socio-technical and biological systems sustain a flow of some physical quantity, such as energy or information, across the their components, it becomes crucial to understand when the flow redistribution can cause global cascades of failures in order to design robust systems, to increase their resilience or to learn how to efficiently dismantle them. In this paper we study the impact that different multiplex topological features have on the robustness of the system when subjected to non-local cascade propagation. We first numerically demonstrate that this dynamics has a critical value at which a small initial perturbation effectively dismantles the entire network, and that the transition appears abruptly. Then we identify that the excess of flow caused by a failure is, in general, more homogeneously distributed the networks in which the average distance between nodes is small. Using this information we find that aggregated versions of multiplex networks tend to overestimate robustness, even though to make the system more robust can be achieved by increasing the number of layers. Our predictions are confirmed by simulated cascading failures in a real multilayer system.
Controlled growth of Mo2C pyramids on liquid Cu surface
Authors: Fan Yixuan , Huang Le , Geng Dechao , Hu Wenping
Published: August 2020

Precise spatial control of 2D materials is the key capability of engineering their optical, electronic, and mechanical properties. However, growth of novel 2D Mo2C on Cu surface by chemical vapor deposition method was revealed to be seed-induced 2D growth, limiting further synthesis of complex Mo2C spatial structures. In this research, we demonstrate the controlled growth of Mo2C pyramids with numerous morphologies, which are characterized with clear terraces within the structures. The whole evolution for Mo2C pyramids in the coursed of CVD process has been detected, posing significant potential in probing growth mechanism. The formation of the Mo2C pyramids arises from the supersaturation-induced nucleation and concentration-gradient driven diffused growth of a new Mo2C layer on the edged areas of intrinsic ones, as supported by STEM imaging. This work provides a novel Mo2C-based pyramid structure and further reveals a sliding growth mechanism, which could offer impetus for the design of new 3D spatial structures of Mo2C and other 2D materials.
Photo-induced doping effect and dynamic process in monolayer MoSe2
Authors: Yang Qian , Xue Yongzhou , Chen Hao , Dou Xiuming , Sun Baoquan
Published: August 2020

Dynamic processes of electron transfer by optical doping in monolayer MoSe2 at 6 K are investigated via measuring time resolved photoluminescence (PL) traces under different excitation powers. Time-dependent electron transfer process can be analyzed by a power-law distribution of t
−α
with α = 0.1–0.24, depending on the laser excitation power. The average electron transfer time of approximately 27.65 s is obtained in the excitation power range of 0.5 to 100 μW. As the temperature increases from 20 to 44 K, the energy difference between the neutral and charged excitons is observed to decrease.
Numerical Investigation of Mixing Performance for a Vertical Turbulence Mixer
Authors: Ya MAO , Zhang Di , Xiong FAN , Lv Yinlei , Chen Zuobing
Published: August 2020

In this work, discrete element method (DEM) was employed to analyze mixing performance of a vertical turbulence mixer. The lacey mixing index was used to quantify mixing degree while a mixing rate was proposed to evaluate mixing speed. Several typical structural and operating parameters affecting mixing performance was investigated including initial loading pattern, rotational speed of stirring shaft and filling level. Results showed that mixing of top-bottom loading is faster than that of side-side loading. Comparing with another factor, stirring shaft rotating speed and filling level had more significant influence. A nearly linear growth and an almost linear decline relationships with mixing rate was found for the rotary speed and filling level respectively. A higher rotational speed or a lower filling level could help form a more intensive granular turbulent flow, resulting in faster mixing. Application of this work provides instruction to optimization of geometry and parameters of mixing systems to improve the quality of the mixing process.
Error Analysis of Distribution Curve
Authors: Zhang Xue-mei , Li Dong , Ma Qing-hua , Jing-yuan HAO
Published: August 2020

11 sets of microscopical data from one same briquette samples have been converted into the Pseudo Strength Index PSI curves, each curve is consisted of 37 points. PSI curves have been used to illustrate the procedures of analyzing and calculating the error. This study shown that even in each PSI curve, there always are same points with the point error greater than 3s, that it is, however, impossible to determine which curve is an “abnormal curve” based on the characteristic (number, size and location) of abnormal points. Because Euclid distance converts the error of a curve into the error of a point, it must first calculate the Euclid distance for the series sets of PSI curves. All 11 Euclid distances is less than the distance limit error of 3s. Therefore, there are no abnormal curves in 11 PSI curves evaluated.
Methane Hydrate Formation Behavior in the Presence of Selected Amino Acids
Authors: Shanker Pandey Jyoti , Jouljamal Daas Yousef , Paul Karcz Adam , Solms Nicolas von
Published: August 2020

Industrial-scale capture, storage, and transport of gases and gas mixtures, such as natural gas, CH4, and CO2 in the form of gas hydrate, is an attractive and feasible solution. However, low formation rate and low water-to-hydrate conversion make it challenging to adopt at commercial scale. Selection of an appropriate chemical as hydrate promoter is crucial to the success of such technologies. Amino acids are seen as potential chemicals to use in such applications due to their environmentally benign nature. However, there are uncertainties around their behavior and classification, since their thermodynamic and kinetic effects on gas hydrates are not well established. In this study, we have identified the kinetics of select amino acids (L-valine, L-methionine, L-histidine, and L-arginine) in methane hydrate formation. Results indicate that hydrophobicity of amino acids plays an important role in methane hydrate kinetics. L-methionine and L-valine show maximum normalized gas uptake and lowest induction time compared to L-histidine and L-arginine.
Preparation and characterization of hydroxyapatite powder and study of hydroxyapatite - alumina Composite
Authors: Saeed Ghazi K. , Essa Abbas F. , Said Saja Abdul-Ammer
Published: August 2020

Hydroxyapatite powder Ca10(PO4)6(OH)2was prepared locally from Iraqi beef bones, and characterization the powder as well as studied purity. A composite of hydroxyapatite-alumina was also prepared with a ratio of alumina 0,5,10,15,20,25% wt. Use polyethylene glycol as a binder with 1% wt by dissolving polyethylene glycol with ethanol (1g: 100ml) at 40 °C and using a magnetic stirrer to obtain a homogeneous solution for the material. Then drying the powder and pressing to prepare compound samples, after that heat treatment at 1350°C for three hours. The physical and mechanical properties studied such as density, porosity, water absorption ratio, hardness and compression resistance, as well as X-ray diffraction and X-ray florescence. X-ray diffraction analysis showed that the hydroxyapatite phase was stabilized for all prepared samples before and after heat treatment with chemical form Ca10(PO4)6(OH)2, the hydroxyapatite showed a stabilization in phase before and after heat treatment without decomposition into different components.
Synthesis and characterization of PVA-Graphene-Ag nanocomposite by using laser ablation technique
Authors: Mohammed Musaab Khudhur , Al-Dahash Ghaleb , Al-Nafiey Amer
Published: August 2020

The PVA-G-Ag nanocomposite have been synthesized effectively by pulsed laser ablation liquid (PLAL) as a considered to be environmentally friendly and free of residues from chemical reactions. The high excellence silver plate (99.99%) and graphite plate (99.99%) was immersed in the polyvinyl alcohol (PVA) solution and irradiated with the Nd-YAG laser at wavelength 1064 nm, power 160 mJ for the silver plate and 80mJ for graphite plate, reiteration rate 6 Hz, 10 ns pulse width and 300 pules for graphite plate and 700 pulse for silver plate. The pure of PVA, PVA-Graphene and PVA-Graphene-Ag nanocomposite were investigated using UV-VIS spectroscopy, FTIR and SEM. The absorption spectra of PVA-Graphene-Ag nanocomposite show the presence of two peaks one 0.4 at 272 and second 0.47 at 403 nm. The optical energy gap (Eg) decreased from 5eV of a pure PVA to 4.6eV of a PVA-G-Ag for indirect allowed transition and therefore, decreased from 4.4eV of a pure PVA to 4.1eV of a PVA-G-Ag for indirect forbidden transition. The transmittance and absorption coefficient have been determined. The SEM images confirmed that homogenous composite without aggregation of the components. The average size of nanoparticles of GNPs and AgNPs for PVA-G and PVA-G-Ag nanocomposite was 130 and 115 nm respectively. The FTIR has demonstrated that the connection between the graphene, silver and polymer network was enough to have stable nanocomposite. This investigation demonstrates that the pulse laser ablation decent instrument to decorated metals on the graphene with the presence of the polymer.
Study the Structural and Optical Properties Pure Copper Sulfide (CuS) Films Prepared by Pulsed Laser Deposition (PLD)
Authors: Chloob Meriam K , Hussain Saleem A
Published: August 2020

In this research, thin film copper sulfide (CuS) were prepared by the pulse laser deposition (PLD) on glass substrate with different thicknesses. The structural and optical properties of copper sulfide thin films were studied and the results of X-ray diffraction (XRD) were analysis. It was found that CuS films have a polycrystalline structure with hexagonal system. The optical properties of the CuS films were studied by measuring and calculating Transmittance and absorbance spectrum respectively within the wavelength range (300-1100) nm. The results of the absorbance spectrum showed that absorbance of the films increase with an increase in the number of pulses (increasing thickness) and that the type of the electronic transition are allowed direct type. The energy gap values between (2.2-2.9) eV, and the it decrease with an increasing of thickness.
Preparation and characterization of (WO3:Co3O4) nano catalyst for fuel cell application
Authors: Mohammed Haleemah J.
Published: August 2020

This research focused on preparing the (WO3: Co3O4) nano catalyst by an electrochemical deposition technique, the electrochemical deposition cell consists of (WO3: Co3O4) electrode as an anode, mesh stainless steel electrode as a cathode and an aqueous solution as an electrolyte. (WO3: Co3O4) were grown on mesh stainless steel electrode, and XRD was used for characterization of nano catalyst, the topography properties were studied by atomic force microscopy (AFM), study the characterization of the electrochemical parameters. For this cell in terms of the impact of hydrogen volume on current, voltage, As well as the study of the effective results of the different concentration electrolyte arrangements extending from 0.14 M to 0.28 M KOH.
Encryption and Steganography a secret data using circle shapes in colored images
Authors: Al-Kateeb Zeena N. , Al-Shamdeen Muna Jaffer , Al-Mukhtar Farah Saad
Published: August 2020

Since the earliest times, people have used the encryption and hiding data to achieve a safe and reliable transfer of important data. This paper propesed a new method for encrypting important data based on the circular shapes information that extracted from the cover image, The encryption process is done using an update of a well known traditional method with simple calculations taking advantage of the coordinates of the center of the main circle as keys extracted from the cover image to reduce the number of keys exchanged between the sender and the recipient and to increase the level of security and confidentiality. The hiding process of the encrypted data is done in pixels that located in the circular areas of the cover image and in three forms of concealment, which providing second encryption, choosing the hiding form depending on the appearing sequence of the character in the text, which makes decode the secure data will be so difficult, the experiments showed that the proposed method was achieved excellent encryption and hiding depending on the coefficients Peak Signal to Noise Ratio analyses (PNSR), Mean Square Error (MSE), and other measurements. The proposed method achieves a complete data recovery ratio where it was Bit Error Rate BER=0.
Review of Different Combinations of Facial Expression Recognition System
Authors: Abd_Almuhsen F. Almudhafer , Khalaf Zainab A.
Published: August 2020

The facial expression recognition (FER) system is a classifier system that attempts to recognize facial expressions based on the analysis of emotion behaviour on the face. The FER system can be implemented by using one classifier or combining multi feature extraction and/or multi classifiers. In general, FER is used with one classifier system to find the best label. Although a classification system is commonly used to find the most likely facial expression, it still produces substantial numbers of errors due to several factors that influence the FER result, such as data quantity, and environmental conditions (i.e. illumination and noise). Therefore, combined multi feature extraction methods and/or multi classifier systems are useful to avoid the single classifier errors. Multi feature extraction or a multi classifier system combination are used to take advantage of different system hypotheses to find an accurate result. This paper is a survey of the latest system combination techniques being used to enhance the classification performance in the FER system; the most recent studies are presented.
Image Classification based on CBIR
Authors: Ali Shaker K. , Sadoon Salah A.
Published: August 2020

In this paper, we present a new way to classify four types of images (Car accidents, Fire, Abnormal objects in street and Digs) which will be sent to four government places; Civil Defence, police station and Municipal. The classification method depends on the Content-Based Image Retrieval (CBIR), where we use a new method. In this method, we use a combination of three methods to extract features from an image; Single Value Decomposition (SVD), Edge Histogram Descriptor (EHD) and Color Auto-Correlogram for Extraction Features. You will use these features to find the closest similarities to the query image from the database images by selecting the closest 3 images, then choosing the class to which the closest two images belong to the retrieved. The combined method showed 100% accuracy in training phase and 100% test phase accuracy.
Performance analysis of Google’s Quick UDP Internet Connection Protocol under Software Simulator
Authors: Albasrawi Saif Talib
Published: August 2020

The QUIC protocol (Quick UDP Internet Connection) is a transport based over UDP Protocol (User Datagram Protocol) that provides safe, reliable and fast service on the Internet. Google proposed it to solve the problem of network delay. It is efficient, fast, and takes up fewer resources. The QUIC gathers the advantages of both TCP and UDP. QUIC is a user-level protocol running on top of UDP, which considered by IETF (Internet Engineering Task Force). Google assumes the response time of page load was short so that end-user performance was better. In this paper, the results presented on a local test using NS-3 (network simulator version 3) that allows QUIC output to test and design choices and possible limitations present the description of the functionalities and the main assumptions of the internet QUIC.
A Prediction of Grain Yield Based on Hybrid Intelligent Algorithm
Authors: Saleh Ibrahim Ahmed , Alawsi Wasan Abdallah , Alsaif Omar Ibrahim , Alsaif Khalil
Published: August 2020

The prediction is most important goals in economic quantitative studies, it basis in design and plan future economic policies properly process over forecasting accuracy. This paper is aiming at the problem salp swarm algorithm (SSA) for predicting grain yield is prone to fall into the local optimal problem. An improved SSA is proposed with combine with back propagation neural network. Using the different advantages of SSA algorithm in global search capabilities, combining the two for further optimize the weight, improve the accuracy and robustness of the grain yield prediction model. The specific implementation is selected from 1963 to 2013.

These methods are used to define agricultural datasets that supports crop growth decision for grain product and its influencing factors were tested as a data set.

The results show that, the improved salp swarm optimization can be classified as a good predict tool for the domestic food production trend in recent years compared with the SSA. This paper briefly introduces three artificial methods BP neural networks, SSA and improved SSA optimization algorithm. The natural behavior of salp, barrel-shaped plankton that are mostly water by weight optimization and combined with mixed-group of intelligent algorithm are simulated. The simulation results of grain production prediction illustrate that the predict precision of the improved SSA is much higher than of both conventional BPNN and SSA techniques and it’s very efficient and practicable.
Feature Extraction Methods: A Review
Authors: Mutlag Wamidh K. , Ali Shaker K. , Aydam Zahoor M. , Taher Bahaa H.
Published: August 2020

Feature extraction is the main core in diagnosis, classification, clustering, recognition, and detection. Many researchers may by interesting in choosing suitable features that used in the applications. In this paper, the most important features methods are collected, and explained each one. The features in this paper are divided into four groups; Geometric features, Statistical features, Texture features, and Color features. It explains the methodology of each method, its equations, and application. In this paper, we made acomparison among them by using two types of image, one type for face images (163 images divided into 113 for training and 50 for testing) and the other for plant images(130 images divided into 100 for training and 30 for testing) to test the features in geometric and textures. Each type of image group shows that each type of images may be used suitable features may differ from other types.
Three terms of derivative free projection technique for solving nonlinear monotone equations
Authors: Mahdi M M , Shiker M A K
Published: August 2020

The derivative-free projection technique is one of the efficient methods for solving nonlinear monotone equations. In this study, three terms of the derivative-free projection method with a monotone line search technique is presented. This method based on extension of a conjugate gradient descent and a developed gradient projection method to solve the nonlinear system of monotone equations. The proposed method can be used for large scale equations due to limited memory requirement. We investigated the global convergence of the suggested approach without requiring differentiability and also the equation is Lipschitz continuous. The numerical results showed that the new algorithm is efficient and promised.
Rényi Entropy for Mixture Model of Multivariate Skew Laplace distributions
Authors: Abid Salah H. , Quaez Uday J.
Published: August 2020

Rényi entropy is an important concept developed by Rényi in information theory. In this paper, we study in detail this measure of information in cases multivariate skew Laplace distributions then we extend this study to the class of mixture model of multivariate skew Laplace distributions. The upper and lower bounds of Rényi entropy of mixture model are determined. In addition, an asymptotic expression for Rényi entropy is given by the approximation. Finally, we give a real data example to illustrate the behavior of entropy of the mixture model under consideration.
Laguerre and Touchard Polynomials for Linear Volterra Integral and Integro Differential Equations
Authors: Abdullah Jalil T. , Ali Haleema S.
Published: August 2020

In this paper, efficient numerical methods are given to solve linear Volterra integral (VI) equations and Volterra Integro differential (VID) equations of the first and second types with exponential, singular, regular and convolution kernels. These methods based on Laguerre polynomials (LPs) and Touchard polynomials (TPs) that convert these equations into a system of linear algebraic equations. The results are compared with one another method and with each other. The results show that these methods are applicable and efficient. In addition, the accuracy of solution is presented and also the calculations and Graphs are done by using matlab2018 program.