bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the Schottky Conjecture for compound structures modeled with line charges
Authors: Harris J. R. , Shiffler D. A. , Jensen K. L. , Lewellen J. W.
Published: June 2019

Schottky's Conjecture (SC) posits that when a compound conductive structure is formed by placing a protrusion on top of an underlying base, the total field enhancement factor is the product of the field enhancement factors that would be produced by the base and protrusion in isolation. This is a powerful concept, which, in principle, allows separate treatment of the electrostatic effects of geometric features occurring at differing length scales. Recent work suggests that the degree to which the SC holds depends on the shape of the protrusion and base, and, in particular, on their relative sizes and their degree of self-similarity. Here, we use a Line Charge Model (LCM) to study the applicability of the SC to compound, quasiellipsoidal structures. The general features of compound structures produced by the LCM are discussed. The SC consistently overpredicted the computed field enhancement factor but was seen to provide reasonable estimates, correct to within a factor of 2 or better, when the protrusion was sufficiently small compared to the base; a dependence of the threshold protrusion height on the base radius was identified. This range of applicability of the SC is more restrictive than that previously reported in the literature, and potential causes of this are discussed.
Response to “Comment on ‘Symmetry in electron and ion dispersion in 1D Vlasov-Poisson plasma’” [Phys. Plasmas 26, 064701 (2019)]
Authors: Trivedi Pallavi , Ganesh Rajaraman
Published: June 2019

Treating electron and ion kinetics on the same physics footing or in a symmetric framework, dispersion relations (ωr, k) for ion and electron modes in a 1D Vlasov-Poisson (VP) plasma were obtained in the limit of weak flattening of the electron and ion distributions. Using this information of (ωr, k), a nonlinear VP solver with a low amplitude, harmonic external forcing has been solved. A possibility of simultaneous excitation of all the electrostatic normal modes was demonstrated in Trivedi et al. [Phys. Plasmas 25, 112102 (2018)]. The main focus of the paper is on the excitation of normal modes by applying a small amplitude external, monochromatic, electric field drive. In order to drive as well as to identify Phase Space Vortices (i.e., Bernstein-Greene-Kruskal/Cnoidal modes, etc.) formed out of the driven nonlinear VP system, assuming local flattening of electron and ion distributions, the real part of the plasma dispersion function for arbitrary ratios of ion to electron masses and temperatures is solved, which is known to be accurate in the low amplitude, harmonic limit, as pointed out by Schamel [Phys. Plasmas 19, 020501 (2012)].
Theoretical studies of the vibrational properties of octahedrane (C12H12): A polyhedral caged hydrocarbon molecule
Authors: Finkenstadt Daniel , Mehl Michael J. , Pederson Mark R. , Richardson Steven L.
Published: June 2019

The vibrational properties of octahedrane (C12H12) are calculated using density-functional theory employing two different computational methods: an all-electron Gaussian orbital approach and a Naval Research Laboratory-tight-binding scheme (NRL-TB) coupled with molecular dynamics (NRL-TBMD). Both approaches yield vibrational densities of states for octahedrane that are in good general agreement with each other. NRL Molecular Orbital Library can also provide accurate infrared and Raman spectra which can be analyzed and compared with experimental results, while NRL-TBMD can be conveniently scaled up for larger finite-temperature simulations. This latter approach is used in our paper to produce a theoretical prediction for a stable room temperature structure of octahedrane.
Lattice location study of low-fluence ion-implanted 124In in 3C-SiC
Authors: Costa A. R. G. , Wahl U. , Correia J. G. , David-Bosne E. , Augustyns V. , Lima T. A. L. , Silva D. J. , da Silva M. R. , Bharuth-Ram K. , Pereira L. M. C.
Published: June 2019

We report on the lattice location of low-fluence ion implanted 124In in single-crystalline 3C-SiC by means of the emission channeling technique using radioactive isotopes produced at the ISOLDE/CERN facility. In the sample implanted at room temperature to a fluence of 4 × 1012 cm−2, 60(9)% of the In atoms were found slightly displaced (0.12–0.20 Å) from substitutional Si sites, with the remainder occupying sites of low crystallographic symmetry, the so-called random sites. For 800 °C implantation, the substitutional In fraction increased to 72(8)% and the displacements from ideal substitutional Si sites were reduced to those expected for the lattice vibrations. These results, in terms of lattice location and disorder, are compared to those on In implanted group IV semiconductors silicon and diamond.
The homogeneity condition: A simple way to derive isotropic periodic sum potentials for efficient calculation of long-range interactions in molecular simulation
Authors: Wu Xiongwu , Brooks Bernard R.
Published: June 2019

Isotropic periodic sum (IPS) is a method to calculate long-range interactions based on the homogeneity of simulation systems. By using the isotropic periodic images of a local region to represent remote structures, long-range interactions become a function of the local conformation. This function is called the IPS potential, which folds long-ranged interactions into a short-ranged potential and can be calculated as efficiently as a cutoff method. Analytic solutions of IPS potentials have been solved for many interaction types. To further simplify the application of the IPS method, this work presents the homogeneity condition, which requires the sum of interaction energies for any particle to be independent of cutoff distances for a truly homogeneous system. Using the homogeneity condition, one can avoid the complicated mathematic work to solve analytic solutions and can instead use simple functions as IPS potentials. Example simulations are performed for model systems of a series of interaction types. Energies, volumes, and their fluctuations from these simulations demonstrate that simple IPS potentials obtained through the homogeneity condition can satisfactorily describe long-range interactions. The homogeneity condition makes the IPS method a convenient way to handle long-range interactions of any type.
Crystallization growth rates and front propagation in amorphous solid water films
Authors: Smith R. Scott , Yuan Chunqing , Petrik Nikolay G. , Kimmel Greg A. , Kay Bruce D.
Published: June 2019

The growth rate of crystalline ice (CI) in amorphous solid water (ASW) films was investigated using reflection absorption infrared spectroscopy. Two different experiments were set up to measure rates of the crystallization front propagation from the underlying crystalline template upward and from the vacuum interface downward. In one set of experiments, layers of ASW (5% D2O in H2O) were grown on a CI template and capped with a decane layer. In isothermal experiments from 140 to 150 K, crystallization was observed from the onset (no induction time) and the extent of crystallization increased linearly with time. In a second set of experiments, uncapped ASW films without a CI template were studied. The films were created by placing a 100 ML isotopic layer (5% D2O in H2O) at various positions in a 1000 ML ASW (H2O) film. The CI growth rates obtained from the two configurations (capped films with a CI template and uncapped films without a CI template) are in quantitative agreement. The results support the idea that for ASW films in a vacuum, a crystalline layer forms at the surface that then acts as a CI template for a growth front that moves downward into the film.
Stochastic model of dispersive multi-step polarization switching in ferroelectrics due to spatial electric field distribution
Authors: Khachaturyan R. , Schultheiß J. , Koruza J. , Genenko Y. A.
Published: June 2019

A stochastic model for polarization switching in tetragonal ferroelectric ceramics is introduced, which includes sequential 90°- and parallel 180°-switching processes and accounts for the dispersion of characteristic switching times due to a nonuniform spatial distribution of the applied field. It presents merging of the recent multistep stochastic mechanism with the earlier nucleation limited switching and inhomogeneous field mechanism models. The model provides a much better description of simultaneous polarization and strain responses over a wide time window and a deeper insight into the microscopic switching mechanisms, as is exemplarily shown by comparison with measurements on lead zirconate titanate.
Ion radiation in icy space environments: Synthesis and radioresistance of complex organic molecules
Authors: Ada Bibang Prudence C. J. , Agnihotri Aditya N. , Augé Basile , Boduch Philippe , Desfrançois Charles , Domaracka Alicja , Lecomte Frédéric , Manil Bruno , Martinez Rafael , Muniz Gabriel S. V. , Nieuwjaer Nicolas , Rothard Hermann
Published: June 2019

Ices are omnipresent in cold regions in space on, e.g., comets, dust grains, transneptunian objects, surfaces of planets and their satellites. The dominant molecule in such ices is water, but also other small molecules or even complex organic molecules (COMs) may be present. Ionizing radiation (UV photons, electrons, ions from cosmic rays or solar wind) induces several physico-chemical processes such as radiolysis. The fragmentation of initial molecules followed by chemical reactions between radicals may lead to formation of new molecules. Furthermore, also implanted projectiles can contribute to chemistry by forming new molecular species. Other observed effects include structural changes (compaction, amorphization) and desorption (sputtering) of particles from the surface. At CIMAP (Caen, France), using the different beam lines of the GANIL facility, and at GSI (Darmstadt, Germany), the interaction of swift highly charged heavy ions with astrophysical ices has been studied in a wide projectile energy range from keV to GeV. Here, two examples of our studies on astrophysical and astrochemical applications will be discussed in detail: 1) the synthesis of COMs under irradiation of ices made of small molecules, and 2) radiosensitivity of COMs such as pyridine, glycine and adenine, both for isolated molecules in the gas phase and in condensed phase. Special emphasis is given on pyridine and pyridine in water matrix.
New possible route of HC3N formation in Titan’s atmosphere
Authors: Mouzay J. , Assadourian C. , Piétri N. , Chiavassa T. , Couturier-Tamburelli I.
Published: June 2019

The structures of the C2N2/C2H2 complex in solid argon matrices have been investigated using FTIR spectroscopy and ab initio calculations, at the aug-cc-pVTZ level of theory. Predicted frequency shifts for the linear structure, characterized by a strong hydrogen bond between the nitrogen of C2N2 and the acetylenic proton were found in good agreement with the ones from the experiment. The photodissociation of C2N2–C2H2 complex trapped in argon matrix at 10 K has been performed at 120 nm. The FTIR measurement and ab initio calculations pointed to the formation of HC3N, HCN and probably HC2NC and HNC as final reactional products. This mechanism route is potentially important for chemical models of the Titan’s atmosphere.
Propyne-water complexes hosted in helium droplets
Authors: Gutiérrez-Quintanilla A. , Briant M. , Mengesha E. , Gaveau Marc-André , Mestdagh J.-M. , Soep B. , Poisson L.
Published: June 2019

A HElium Nanodroplet Isolation (HENDI) experiment was performed to explore the absorption spectrum of the propyne-water complex (CH3CCH⋯H2O). Two spectral regions were investigated, near the CH stretch v1 of the propyne moiety and near the asymmetric stretch v3 of the water moiety. Ab-initio calculations were performed at the MP2/aug-cc-pVTZ level to estimate the spectroscopic constants of the free complex. This provided the necessary parameters to simulate the absorption spectrum of the complex and thus facilitate the interpretation of the experiment. The observed spectrum is consistent with a structure of the complex where two H-bonds between water and propyne form a five member ring. The later was predicted by Lopes et al. [J. Mol. Struct. 834, 258 (2007)].
Valine infrared absorbance at cryogenic temperatures
Authors: da Costa C. A. P. , da Silveira E. F.
Published: June 2019

The amino acid L-valine is analyzed by Fourier Transform InfraRed Spectroscopy (FTIR) in the 40–300 K temperature range. A valine sample was deposited onto a ZnSe substrate, cooled down to 40 K and warmed up back to 300 K, annealed at 120°C for 12 h, cooled down to 40 K and warmed up again to 300 K. FTIR spectra were acquired in transmission mode during this thermal excursion. It was observed that: (i) no phase transition has occurred; (ii) as temperature decreases, the band absorbances increase linearly and the band widths become narrower; (iii) compared to 300 K values, the integrate absorbances (peak areas) at 40 K are 40–100% higher and bandwidths are about half; (iv) the FTIR spectrum behaviors of the annealed and non-annealed samples are similar. The sample is considered to be constituted only by valine zwitterions; bandwidth decrease is explained partially by Doppler effect; absorbance enhancement at low temperatures is caused by stronger Van der Walls forces. These general conclusions are expected to be similar for other amino acids.
Calculations reveal new insights into heat diffusion in silicon
Authors: Larter Raima
Published: June 2019

Monte Carlo calculations based on empirical and ab initio methods show that acoustic phonons, not optical phonons as assumed, receive the majority of energy transferred from hot electrons in silicon.
Performance investigation of optical wavelength conversion using a newly designed highly nonlinear ultra-flattened dispersion fibre
Authors: Selvendran S. , Sivanantharaja A.
Published: June 2019

We report an analysis of the wavelength conversion using a newly designed highly nonlinear ultra-flattened dispersion fibre (HN-UFF) for different signal modulation formats. A new technical solution is presented for high bit rate wideband wavelength conversion without any additional pump signals. Two-channel 80 Gb s−1 modulated signals with differential quadrature phase shift keying (DQPSK) are considered for wavelength conversion using four wave mixing (FWM) technique in a newly designed HN-UFF without additional pump signals. It is found that even when the input signal frequency spacing is increased beyond 2 THz, DQPSK modulation with carrier-suppressed return-to zero (CSRZ), or CSRZ-DQPSK, gives a better value of flattened conversion efficiency and Q factor. The impact of input power on conversion efficiency and effective flatness is also investigated. The performance parameters, such as conversion efficiency, Q factor, log of bit error rate (BER), received signal power and power penalty, are analysed.
Precision loss measurements in short lengths of optical fibre by reflectometry without using Rayleigh scattering
Authors: Gorshkov B.G. , Gorshkov G.B. , Zhukov K.M.
Published: June 2019

To improve accuracy of light attenuation measurements in optical fibres, especially in short ones, tens and hundreds of metres in length, we propose rejecting a conventional reflectometric approach based on Rayleigh scattering intensity measurements. To this end, we propose for the first time the use of boson peaks in Raman scattering, which, on the one hand, produce no interference effects and no related noise in reflectograms, and, on the other, lie within the C-band. Even at a fibre length as short as 50 m, the attenuation measurement error does not exceed 0.002 dB km−1. We demonstrate the possibility of compensating for the temperature variation of boson peak intensity by concurrently obtaining a reflectogram for the anti-Stokes line of the fundamental Raman band.
Control of the spectral parameters of neodymium ions in anisotropic crystals with a scheelite structure
Authors: Shilova G.V. , Sirotkin A.A. , Zverev P.G.
Published: June 2019

The spectral parameters of neodymium ions in anisotropic YLiF4, SrMoO4, PbMoO4, CaMoO4, SrWO4, and BaWO4 crystals with a scheelite structure are experimentally studied in the region of 1 μm. The luminescence spectra of neodymium ions at the 4F3/2 → 4I11/2 transition in these crystals exhibit pronounced polarisation dependences. It is shown that, using different orientations of the active laser element and separating a particular radiation polarisation, one can control the spectral dependence of the active medium gain, switch the laser wavelength, and create dual-wavelength lasers. A dual-wavelength Nd3+ : YLiF4 laser emitting at λ = 1047 and 1053 nm with identical linear polarisations and good temporal and spatial matching is demonstrated.
Stimulated emission of AlGaN layers grown on sapphire substrates using ammonia molecular beam epitaxy
Authors: Lutsenko E.V. , Rzheutski M.V. , Vainilovich A.G. , Svitsiankou I.E. , Nagorny A.V. , Shulenkova V.A. , Yablonskii G.P. , Alekseev A.N. , Petrov S.I. , Solov’ev Ya.A. , Pyatlitski A.N. , Zhigulin D.V. , Solodukha V.A.
Published: June 2019

By optimising the growth temperature of the AlGaN layers and using high-temperature AlN buffer layers, high-quality Al
x
Ga1 – x
N layers (x = 0.15, 0.21, 0.26, and 0.3) were obtained, in which stimulated emission in the UV spectral range 330 – 297 nm was implemented with the threshold intensity of excitation I
th ≈ 0.7 – 1.4 MW cm−2, respectively. It is found that the threshold value of the stimulated emission of AlGaN layers grown by molecular beam epitaxy is largely determined by the intensity of the process of thermal decomposition of GaN, which affects the surface morphology and, consequently, the amount of optical scattering loss. It is shown that no pronounced localisation of nonequilibrium charge carriers occurs in the AlGaN layers, which is manifested in the absence of a large Stokes shift and in the realisation of optical amplification at transitions in an electron-hole plasma, and also indicates a relatively homogeneous material composition.
Active region of a functionally integrated laser – modulator
Authors: Ryndin E.A. , Konoplev B.G.
Published: June 2019

A method for the functional integration of injection lasers and modulators of generated light in a single heterostructure with spatially displaced quantum wells in the conduction and valence bands, formed by the second-type heterojunctions, is proposed. The structures and energy band diagrams of the active regions of functionally integrated lasers – modulators with amplitude and frequency modulation are considered. A physical – topological model and a technique for numerical simulation of lasers – modulators is proposed. It is shown that the maximum modulation frequencies for the proposed heterostructures, in contrast to the same frequencies implemented under pump current modulation, are not limited by the duration of transients in the laser power supply circuit and the carrier lifetime in the laser active region but are determined by the photon lifetime in the cavity.
Widening participation of Māori and Pasifika students in health careers: evaluation of two health science academies
Authors: Middleton Lesley , Tanuvasa Ausaga Faasalele , Pledger Megan , Grace Nicola , Smiler Kirsten , Loto-Su'a Tua Taueetia , Cumming Jacqueline
Published: June 2019

Objective
The aim of the present study was to evaluate the short-term outcomes of two health science academies established by a district health board in South Auckland, New Zealand, to create a health workforce pipeline for local Māori and Pasifika students.

Methods
A mixed-methods approach was used, involving background discussions with key informants to generate an initial logic model of how the academies work, followed by secondary analysis of students’ records relating to retention and academic achievement, a survey of senior academy students’ interest in particular health careers and face-to-face interviews and focus groups with students, families and teachers.

Results
Academy students are collectively achieving better academic results than their contemporaries, although selection decisions are likely to contribute to these results. Academies are retaining students, with over 70% of students transitioning from Year 11 to Years 12 and 13. Senior students are expressing long-term ambitions to work in the health sector.

Conclusions
Health science academies show promise as an innovative approach to supporting Māori and Pasifika students prepare for a career in the health professions. Evaluating the long-term outcomes of the academies is required to determine their contribution to addressing inequities in the local health workforce.

What is known about the topic?
Despite progress in health workforce participation for underrepresented indigenous and ethnic minority groups in New Zealand, significant disparities persist. Within this context, a workforce development pipeline that targets preparation of secondary school students is recommended to address identified barriers in the pursuit of health careers.

What does this paper add?
We provide an evaluation of an innovative district health board initiative supporting high school students that is designed to ensure their future workforce is responsive to the needs of the local community.

What are the implications for practitioners?
The findings have implications for decision makers in health workforce planning regarding the benefits of investing at an early stage of the workforce development pipeline in order to build an equitable and diverse health professions workforce.
Unusual new species of Styphelia (Ericaceae, Epacridoideae, Styphelieae) from north-eastern Australia
Authors: Crayn Darren M. , Puente-Lelièvre Caroline , Jensen Rigel
Published: June 2019

Styphelia geniculata Crayn and S. piliflora Crayn are described, phylogenetically placed and compared with related species. Their relationships within Ericaceae tribe Styphelieae, resolved by phylogenetic analysis of plastid and nuclear DNA sequences, support their description in the expanded genus Styphelia. Illustrations, pollen scanning electron micrographs, distribution maps and a key to the species and related northern Queensland taxa are provided, along with notes on the ecology and conservation status.
Unfolded states under folding conditions accommodate sequence-specific conformational preferences with random coil-like dimensions
Authors: Peran Ivan , Holehouse Alex S. , Carrico Isaac S. , Pappu Rohit V. , Bilsel Osman , Raleigh Daniel P.
Published: June 2019

Significance

The tools of structural biology afford high-resolution descriptions of folded states of proteins. However, an atomic-level description of unfolded states under folding conditions has remained elusive. Challenges arise from the pronounced conformational heterogeneity and the very low population of unfolded states under folding conditions. We have combined a series of time-resolved biophysical experiments with all-atom simulations and polymer theory to obtain a high-resolution description of unfolded ensembles under folding conditions. These unfolded states are characterized by discernible sequence-specific conformational preferences. These preferences are averaged over by conformational fluctuations, giving rise to ensemble-averaged properties that are consistent with those of canonical random coils. Our findings are relevant to understanding functional and pathological interactions involving unfolded forms of proteins.
On the occurrence of cytochrome P450 in viruses
Authors: Lamb David C. , Follmer Alec H. , Goldstone Jared V. , Nelson David R. , Warrilow Andrew G. , Price Claire L. , True Marie Y. , Kelly Steven L. , Poulos Thomas L. , Stegeman John J.
Published: June 2019

Genes encoding cytochrome P450 (CYP; P450) enzymes occur widely in the Archaea, Bacteria, and Eukarya, where they play important roles in metabolism of endogenous regulatory molecules and exogenous chemicals. We now report that genes for multiple and unique P450s occur commonly in giant viruses in the
Mimiviridae
,
Pandoraviridae
, and other families in the proposed order Megavirales. P450 genes were also identified in a herpesvirus (
Ranid herpesvirus 3
) and a phage (
Mycobacterium
phage Adler). The Adler phage P450 was classified as CYP102L1, and the crystal structure of the open form was solved at 2.5 Å. Genes encoding known redox partners for P450s (cytochrome P450 reductase, ferredoxin and ferredoxin reductase, and flavodoxin and flavodoxin reductase) were not found in any viral genome so far described, implying that host redox partners may drive viral P450 activities. Giant virus P450 proteins share no more than 25% identity with the P450 gene products we identified in
Acanthamoeba castellanii
, an amoeba host for many giant viruses. Thus, the origin of the unique P450 genes in giant viruses remains unknown. If giant virus P450 genes were acquired from a host, we suggest it could have been from an as yet unknown and possibly ancient host. These studies expand the horizon in the evolution and diversity of the enormously important P450 superfamily. Determining the origin and function of P450s in giant viruses may help to discern the origin of the giant viruses themselves.
Who stole what from whom?
Authors: Fernández-Martínez Nicolás José , Faber Pamela
Published: June 2019

Drawing on the Lexical Grammar Model, Frame Semantics and Corpus Pattern Analysis, we analyze and contrast verbs of stealing in English and Spanish from a lexico-semantic perspective. This involves looking at the lexical collocates and their corresponding semantic categories that fill the argument slots of verbs of stealing. Our corpus search is performed with the Word Sketch tool on Sketch Engine. To the best of our knowledge, no study has yet taken advantage of the Word Sketch tool in the study of the selection preferences of verbs of stealing, let alone a semantic, cross-linguistic study of those verbs. Our findings reveal that English and Spanish verbs of stealing map out the same underlying semantic space. This shared conceptual layer can thus be incorporated into an ontology based on deep semantics, which could in turn enhance NLP tasks such as word sense disambiguation, machine translation, semantic tagging, and semantic parsing.
Is children’s wellbeing different from adults’ wellbeing?
Authors: Cormier Andrée-Anne , Rossi Mauro
Published: June 2019

Callgeneralismabout children’s and adults’ wellbeing the thesis that the same theory of wellbeing applies to both children and adults. Our goal is to examine whether generalism is true. While this question has not received much attention in the past, it has recently been suggested that generalism is likely to be false and that we need to elaborate different theories of children’s and adults’ wellbeing. In this paper, we defend generalism against the main objections it faces and make a positive case for it.
Stochastic thermodynamics of self-oscillations: the electron shuttle
Authors: Wächtler Christopher W , Strasberg Philipp , Klapp Sabine H L , Schaller Gernot , Jarzynski Christopher
Published: June 2019

Self-oscillation is a phenomenon studied across many scientific disciplines, including the engineering of efficient heat engines and electric generators. We investigate the single electron shuttle, a model nano-scale system that exhibits a spontaneous transition towards self-oscillation, from a thermodynamic perspective. We analyse the model at three different levels of description: The fully stochastic level based on Fokker–Planck and Langevin equations, the mean-field (MF) level, and a perturbative solution to the Fokker–Planck equation that works particularly well for small oscillation amplitudes. We provide consistent derivations of the laws of thermodynamics for this model system at each of these levels. At the MF level, an abrupt transition to self-oscillation arises from a Hopf bifurcation of the deterministic equations of motion. At the stochastic level, this transition is smeared out by noise, but vestiges of the bifurcation remain visible in the stationary probability density. At all levels of description, the transition towards self-oscillation is reflected in thermodynamic quantities such as heat flow, work and entropy production rate. Our analysis provides a comprehensive picture of a nano-scale self-oscillating system, with stochastic and deterministic models linked by a unifying thermodynamic perspective.
Optical and electrical properties of two-dimensional anisotropic materials
Authors: Zhou Ziqi , Cui Yu , Tan Ping-Heng , Liu Xuelu , Wei Zhongming
Published: June 2019

Two-dimensional (2D) anisotropic materials, such as B-P, B-As, GeSe, GeAs, ReSe2, KP15 and their hybrid systems, exhibit unique crystal structures and extraordinary anisotropy. This review presents a comprehensive comparison of various 2D anisotropic crystals as well as relevant FETs and photodetectors, especially on their particular anisotropy in optical and electrical properties. First, the structure of typical 2D anisotropic crystal as well as the analysis of structural anisotropy is provided. Then, recent researches on anisotropic Raman spectra are reviewed. Particularly, a brief measurement principle of Raman spectra under three typical polarized measurement configurations is introduced. Finally, recent progress on the electrical and photoelectrical properties of FETs and polarization-sensitive photodetectors based on 2D anisotropic materials is summarized for the comparison between different 2D anisotropic materials. Beyond the high response speed, sensitivity and on/off ratio, these 2D anisotropic crystals exhibit highly conduction ratio and dichroic ratio which can be applied in terms of polarization sensors, polarization spectroscopy imaging, optical radar and remote sensing.
Comparison of tunneling currents in graphene nanoribbon tunnel field effect transistors calculated using Dirac-like equation and Schrödinger's equation
Authors: Suhendi Endi , Hasanah Lilik , Rusdiana Dadi , Noor Fatimah A. , Kurniasih Neny , Khairurrijal
Published: June 2019

The tunneling current in a graphene nanoribbon tunnel field effect transistor (GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrödinger's equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method (TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrödinger's equation.
Electronic band structures and optical properties of atomically thin AuSe: first-principle calculations
Authors: Bai Pengxiang , Guo Shiying , Zhang Shengli , Qu Hengze , Zhou Wenhan , Zeng Haibo
Published: June 2019

As a large family of 2D materials, transition metal dichalcogenides (TMDs) have stimulated numerous works owing to their attractive properties. The replacement of constituent elements could promote the discovery and fabrication of new nano-film in this family. Using precious metals, such as platinum and palladium, to serve as transition metals combined with chalcogen is a new approach to explore novel TMDs. Also, the proportion between transition metal and chalcogen atoms is found not only to exist in conventional form of 1 : 2. Herein, we reported a comprehensive study of a new 2D precious metal selenide, namely AuSe monolayer. Based on density functional theory, our result indicated that AuSe monolayer is a semiconductor with indirect band-gap of 2.0 eV, which possesses superior dynamic stability and thermodynamic stability with cohesive energy up to –7.87 eV/atom. Moreover, it has been confirmed that ionic bonding predominates in Au–Se bonds and absorption peaks in all directions distribute in the deep ultraviolet region. In addition, both vibration modes dominating marked Raman peaks are parallel to the 2D plane.
The Role of the information technique in Sustainable Strategic Planning _ Nejaf Provenance as case study
Authors: Sabree Ali Amna Hussain
Published: June 2019

The Spatial Analysis of the Potential Development in Al Najaf province by using modern techniques as one of the planning methods that helps taking the planning decision by depending on the Planning indicators that reclaimed from the Strategic analysis and the digital Spatial interaction as real indicators for the current and subsequent stage to nominate the development substitute which achieve the strategic capacity of the development elements and its capability to exploit it better towards achieving the set goals by choosing a model of Strategic Spatial based on the development planning decisions and future forecast in maximize and exploit the opportunities also reducing the weakness points as well as using the strength points to reach the Balance, Efficiency and Justice achievement in distributing the fruits of development which contribute in achieving Sustainable development depending on the indicators of the Sustainable Strategic Planning and sustainable indicators.
Effect of sustainable palm fiber on high strength concrete properties
Authors: Aljalawi Nada M. F.
Published: June 2019

Date palm fiber is one of the common wastes available in the M. E. countries essentially Iraq. The aim of search to investigate the performance and effects of fiber date palm on the mechanical properties of high strength concrete, this fiber was used in three ratio 2, 4 and 6 % by vol. of concrete at ages of (7, 28, 90) days. Results demonstrated improvement in the compressive strength increased 19.2 %, 23.6%, 24.9 % for 2%, 4%, 6% of fiber respectively at age 28 days. Flexural strength increases 47.6%, 66.2%, 93.8% form (2,4,6) % of fiber respectively at age 28 days. Density increase about 0.41%, 0, 61 % 0.69 % for (2,4,6) % of fiber respectively at age 28. Absorption water decrease 7.4 %, 14.8%, 7.4% for (2,4,6) % of fiber respectively at age 28. The ideal of sustainability has stabilized the exploitation of manufacturing and agrarian trash in the unit to replace traditional item. In order to build low cost green building, requires produce new units or sustainability unit.
Value as a Criticism Strategy for Contemporary Architecture Products
Authors: Hashim Basim Hassan , Hamza Shaimaa M.
Published: June 2019

Value is one of the most important strategies for criticism and evaluation of architectural projects, by providing the criteria by which to select and evaluate architectural projects. Value concept of the projects varies according to the designer’s estimate of the project, and their different types of value, aesthetic, expressive, functional, technological, and sustainable based on which the project is designed. Therefore, the research aims to know the importance of value, its types, and apply them to a set of international and local architectural projects, to demonstrate the type of value used in each project, because of the lack of clarity of knowledge about the concept of value as a strategy of criticism and evaluation of projects in architectural competitions. The hypothesis of the research is the reciprocity of the choice of aesthetic, expressive, functional, technological and sustainable values in the criticism and evaluation of architectural projects. The research found that value is important in the process of selecting and evaluating architectural products and practice, through cognitive components as a criterion for choice, emotional components as a criterion for assessment, and behavioral components as a criterion for practice. The research recommended the preparation of criticism and evaluation criteria that include aesthetic, expressive, functional, technological and sustainable value indicators for evaluating projects in all departments of architecture.
Indicators for Sustainable housing
Authors: Shama Zaineb Salman , Motlak Jamal Baqir
Published: June 2019

With the beginning of the twenty-first century, the world is undergoing rapid changes, but adequate and affordable housing remains a concern for all countries. This requires a new understanding of housing to address pressing issues such as slum reduction, economic and social development and climate change. Housing is no longer just a roof but is now playing an important role in achieving sustainable development - as envisioned in the idea of sustainable housing. Sustainable housing provides a comprehensive framework for the form of sustainable housing policies and practical actions. Although sustainable housing is often viewed from a resource-based perspective, it is a more comprehensive approach that recognizes the multiple functions of housing as a physical and social system. Sustainable housing policies must deal with affordability, social and cultural equity and the economic impact of housing and contribute to making neighborhoods healthier and more sustainable. The study deals with a number of issues related to sustainable housing, focusing on the relationship between the concept of sustainable development and housing and the most important concepts in the recent trends in urban planning related to sustainable housing for the purpose of developing a system of indicators for evaluating housing sustainability based on the views of experts in housing and urban planning. The research assumes that housing indicators provide an important step towards sustainable housing, and indicators must be evaluated in a broad context because they are influenced by a wide range of indicators that affect the quality of life of society. The research aims to develop indicators that represent sustainable housing through local privacy, helping to bring together the linkages between housing and sustainability issues together.
The Concept of Socio Hydrology and Spatial Organization of Human Settlements (An Analytical Study of Rural Wasit District at Wasit Governorate)
Authors: Al Bashagha Harth Hazim Aziz , Jalil Mustafa Abdul
Published: June 2019

The rural stabilizers in Iraq have a basic identity, which is the agricultural identity. Therefore, they depend on the hydrologic factor (directly or indirectly) in their formation and realization of the pattern. With the formation of the patterns and stability of the rural stabilizers, the interaction and mutual influence begins between society and hydrology with time, and given the emergence of the concept of global hydrology collectively as a new concept dealing with the study of the interrelationship between society and water with time. This concept was introduced in this study for the purpose of analyzing the rural situation of Wasit, and model of their design in 1976 where the agricultural Dujailah industrial project carried out. The project includes network reclamation and stations of dairy cows and plants. This leads to the main spatial indicators (population, cultivated areas, livestock, water resources, educational services, and health services), in this study we try to determine what is the most interactive and influential indicator on the society and thus on the formation of the patterns of rural stabilizers in Wasit region. It also discusses the impact and interaction of the rural society with the project of reclamation and analysis of the results and their discussion based on a spatial statistical method. The first model represents the social side and the second model represents the economic side. The results are analyzed to determine the importance of the concept of social hydrology in the process of rural development, it is important to introduce this concept in the spatial organization of the rural stability along with the service sectors to achieve a state of functional integration between the economic structure and service sectors of the study area.
Sustainable Used of Natural Coagulants Aid for Enhancing the Performance of Alum to Treat Turbid Water
Authors: Ali Ahmed Hassoon , Tlaiaa Younis Swadi , Razak Nasir Zainab Abdul
Published: June 2019

Within the last ten years, many worried about the connection between Alzheimer disease and the residuals of aluminum in the water treatment. Therefore, there has been an increasing interest in developing substances that cause natural coagulation. In this study the effect of using natural coagulants, peeled nut extract and apricot tree gum with alum Al2(SO4)3 and compared to alum alone was investigated. The study was carried out by a series of jar tests with initial turbidity of 22 and 100 NTU. These values were taken to represent the minimum and maximum water turbidity of Tigris River in Baghdad. Different doses of natural coagulation and alum were used (ranged from 2-12 mg / L). After treatment, the turbidity has been measured and the results reflected that, the use of apricot gum and peels nut as coagulant aids with alum were better compared to the use of alum alone and that using of 50% alum + 50% peels nut gave maximum removal efficiency of 95 and 88% for initial turbidity of 22 and 100 NTU respectively and that using of 50% alum + 50% apricot gum gave maximum removal efficiency of 90 and 85% for initial turbidity of 22 and 100 NTU respectively. At the same time, this reduced the alum dose from 12 mg/L to 6 mg/L. This process will reflect on saving cost and reduce health risk associated with using of alum.
New Attempted Moving Towards Understanding Urban System Behavior
Authors: Khalil Safiya M. , Ebrahim Mustafa A.
Published: June 2019

System is considering useful concept to describe the spatial forms (city, region, etc.). Additionally, diverse fields that undertaking finds it sharpen their understanding and improve their practice.by exploring the literatures in this field; here we argue that there are two forces that effect in urban system behavior: 1stone vertical force the value which changing according to urban rent and another social factor related to place. The 2ndone horizontal force the flow changing according to movement of matter, energy, and information. That may lead to new perspective to see the city as a system and highlight the way for planners to sustain their cities.
Dynamic Preemption Algorithm to Assign Priority for Emergency Vehicle in Crossing Signalised Intersection
Authors: Salih Amenah A. , Lewis Andrew , Chung Edward
Published: June 2019

Emergency vehicle (EV) services save lives around the world. The necessary fast response of EVs requires minimising travel time. Preempting traffic signals can enable EVs to reach the desired location quickly. Most of the current research tries to decrease EV delays but neglects the resulting negative impacts of the preemption on other vehicles in the side roads. This paper proposes a dynamic preemption algorithm to control the traffic signal by adjusting some cycles to balance between the two critical goals: minimal delay for EVs with no stop, and a small additional delay to the vehicles on the side roads. This method is applicable to preempt traffic lights for EVs through an Intelligent Transportation System. A Matlab-Vissim Interface was implemented to simulate the intersection and apply the proposed algorithm. The results show a significant decrease in delays for both EVs and other traffic.
Application of Variable Pulsed Irrigation Algorithm (VPIA) for Runoff Losses Reduction: Case Study of Different Soil Types
Authors: Al Al-Baaj Aymen A. , Lewis Andrew , Alfatlawi Thair J. M. , Kaparaju Prasad
Published: June 2019

The low-pressure sprinklers have been widely used to replace the high-pressure impact sprinklers in the lateral move sprinkler irrigation system due to its low operating cost and high efficiency. However, runoff losses under the low-pressure sprinkler irrigation machine can be significant. This study aims to evaluate the performance of the variable pulsed irrigation algorithm (VPIA) in reducing the runoff losses under low-pressure lateral move sprinkler irrigation machine for three different soil types. The VPIA uses the ON-OFF pulsing technique to reduce the runoff losses by controlling the number and width of the pulses considering the soil and the irrigation machine properties. Also, the VPIA aims to achieve a balance between four critical goals: reduce the runoff losses, deliver the highest possible irrigation depth, ensure a high level of water distribution uniformity in the direction movement, and with the lowest number of pulses. From a wide range of pulses numbers and widths tested applying a certain water depth to three soil types (Loamy Sand, Sandy Loam, Loam), the best solution that satisfies the algorithm goals was selected. A MATLAB code was written to simulate the soil infiltration rate, the sprinkler application rate, and to apply the proposed algorithm. The simulation results show a runoff reduction of at least 91.76% for Loamy sand, 90.7% for Sandy Loam, and 97.79% for Loam soils with a high level of distribution uniformity while delivering the highest possible irrigation depth using the lowest number of pulses.
Development of Vehicle Queue Model for Selected Signalized Intersections at CBD in Sulaymaniyah City
Authors: Khaleel Saad M , Sofia Gandhi G , Kadhim Ali J
Published: June 2019

The objective of this paper is to develop an empirical model for queue length prediction at Signalized Intersections as a function of influence traffic and geometric features. Two Signalized Intersections with different characteristics are selected in Sulaymaniyah city. Geometric design elements were measured through a field survey and satellite image. Field traffic volumes, signal timings and phasing, control delay and queue length were measured during peak and off-peak periods using video recording technique. A statistical approach (SPSS) is used to develop a queue length model. The statistical analysis indicates that both geometric and traffic variables have a significant effect on queue length. The regression model, developed to estimate queue length, shows good correlation with field values. The model has been compared with the SYNCHRO software model. It is found that although SYNCHRO queue overestimates at high v/c (range, but it does not have a significant difference with the field queue a 95% confidence level.
Evaluation of the Effect of Mixing Conditions of Micro-Silica Modified Asphalt Binder
Authors: Zghair Hussein H , Joni Hasan H , Hassan Maan S
Published: June 2019

The aim of this study was to improve an effective approach to the processing of asphalt binder modified with micro-silica particles. Various mixer type (mechanical and high shear), revaluation rates (2000, 4000 and 6000 rpm), and two mixing time (30 and 60 minutes), were adopted. Three micro-silica contents 2%, 4%, and 6% by weight of asphalt cement were added. The asphalt binder was prepared at temperature of 140 °C. Comparisons were made to evaluate the properties of the modified asphalt binder such as penetration grade, softening point temperature, temperature sensitivity, rotational viscosity and ductility. Results of this study showed that the use of micro silica as a modifier was helpful in enhancing the physicals properties of the asphalt binder. In general, it was found that the penetration value decreased and softening point temperature, as well as the viscosity value, increased and the temperature sensitivity was improved. Furthermore, high shear mixing was more practical particularly to achieve a good dispersion of micro silica particles into asphalt binder and obtained a homogenous composite binder. Finally, the tested specimens showed 6% of micro silica was adequate to improve the physical properties of asphalt and become more suitable for constructing the highway pavements in hot weather conditions.