Physical Sciences and Mathematics Commons^™

Introduction To Wood Structure And Characteristics, Terry Conners

Agriculture and Natural Resources Publications

Wood is identified using the features and tools that are appropriate to the size of the sample. Large timbers are identified by looking at the color, the appearance of the end and side grain, whether a saw cuts cleanly or leaves lots of splinters behind, whether the wood has straight or curly drying cracks, and so forth. The hardness and density provide valuable information as well. For smaller pieces of wood, it’s more practical to look directly at the wood cells with a 10X hand lens (also called a loupe). Different species have different characteristics and combinations of these features …

First Steps In Identifying Wood, Terry Conners

Agriculture and Natural Resources Publications

Wood samples need to be identified for all sorts of reasons, and they come in all shapes, sizes and conditions. I’ve received samples that were sound, samples that were waterlogged, samples that were rotted or otherwise degraded, painted samples, furniture samples, even samples containing wood preservatives. Most of the samples I receive have a North American origin, but I also receive pieces from art museums and antique dealers that can originate from just about anywhere. This sometimes means that identifying the sample by a common name alone doesn’t provide enough information.

Structure Symmetry Determination And Magnetic Evolution In Sr2Ir1−XRhXO4, Feng Ye, Xiaoping Wang, Christina Hoffmann, Jinchen Wang, Songxue Chi, Masaaki Matsuda, Bryan C. Chakoumakos, Jaime A. Fernandez-Baca, Gang Cao

Physics and Astronomy Faculty Publications

We use single-crystal neutron diffraction to determine the crystal structure symmetry and the magnetic evolution in the rhodium-doped iridates Sr₂Ir_1−xRh_xO₄ (0≤ x ≤ 0.16). Throughout this doping range, the crystal structure retains a tetragonal symmetry (space group I4₁/a) with two distinct magnetic Ir sites in the unit cell forming staggered IrO₆ rotation. Upon Rh doping, the magnetic order is suppressed and the magnetic moment of Ir⁴⁺ is reduced from 0.21μ_B/Ir for x=0 to 0.18μ_B/Ir for x=0.12. The magnetic structure …

Guidelines For Good Mathematical Writing, Francis Su

All HMC Faculty Publications and Research

Communicating mathematics well is an important part of doing mathematics. Many of us know from writing papers or giving talks that communicating effectively not only serves our audience but also clarifies and structures our own thinking. There is an art and elegance to good writing that every writer should strive for. And writing, as a work of art, can bring a person great personal satisfaction.

Within the MAA, we value exposition and mathematical communication. In this column, I’m sharing the advice I give my students to help them write well. There are more extensive treatments (e.g., see Paul Halmos’s How …

Moments Of The Neutron G2 Structure Function At Intermediate Q2, Wolfgang Korsch, P. Solvignon, N. Liyanage, J.-P. Chen, Seonho Choi, K. Slifer, K. Aniol, T. Averett, W. Boeglin, A. Camsonne, G. D. Cates

Physics and Astronomy Faculty Publications

We present new experimental results for the ³He spin structure function g₂ in the resonance region at Q² values between 1.2 and 3.0(GeV/c)². Spin dependent moments of the neutron were extracted. Our main result, the inelastic contribution to the neutron d₂ matrix element, was found to be small at ⟨Q²⟩=2.4(GeV/c)² and in agreement with the lattice QCD calculation. The Burkhardt-Cottingham sum rule for ³He and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region.

Star Formation And Quenching Among The Most Massive Galaxies At Z ∼ 1.7, C. Mancini, A. Renzini, E. Daddi, G. Rodighiero, S. Berta, N. Grogin, Dale D. Kocevski, A. Koekemoer

Physics and Astronomy Faculty Publications

We have conducted a detailed object-by-object study of a mass-complete (M_* ≥ 10¹¹ M_⊙) sample of 56 galaxies at 1.4 ≤ z ≤ 2 in the Great Observatories Origins Deep Survey-South field, showing that an accurate deblending in 24 μm images is essential to properly assign to each galaxy its own star formation rate (SFR), whereas an automatic procedure often fails. This applies especially to galaxies with SFRs below the main sequence (MS) value, which may be in their quenching phase. After that, the sample splits evenly between galaxies forming stars within a factor of …

P-Manga: Full Spectral Fitting And Stellar Population Maps From Prototype Observations, David M. Wilkinson, Claudia Maraston, Daniel Thomas, Lodovico Coccato, Rita Tojeiro, Michele Cappellari, Francesco Belfiore, Matthew Bershady, Mike Blanton, Kevin Bundy, Sabrina Cales, Brian Cherinka, Niv Drory, Eric Emsellem, Hai Fu, David Law, Cheng Li, Roberto Maiolino, Karen Masters, Christy Tremonti, David Wake, Enci Wang, Anne-Marie Weijmans, Ting Xiao, Renbin Yan, Kai Zhang, Dmitry Bizyaev, Jonathan Brinkmann, Karen Kinemuchi, Daniel Oravetz, Kaike Pan, Audrey Simmons

Physics and Astronomy Faculty Publications

MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yr SDSS-IV (Sloan Digital Sky Survey IV) survey that will obtain resolved spectroscopy from 3600 to 10 300 Å for a representative sample of over 10 000 nearby galaxies. In this paper, we derive spatially resolved stellar population properties and radial gradients by performing full spectral fitting of observed galaxy spectra from P-MaNGA, a prototype of the MaNGA instrument. These data include spectra for 18 galaxies, covering a large range of morphological type. We derive age, metallicity, dust, and stellar mass maps, and their radial gradients, using high spectral-resolution stellar …

Long-Term Midlatitude Mesopause Region Temperature Trend Deduced From Quarter Century (1990-2014) Na Lidar Observations, Chiao Y. She, D. A. Krueger, Tao Yuan

All Physics Faculty Publications

The long-term midlatitude temperature trend between 85 and 105 km is deduced from 25 years (March 1990-December 2014) of Na Lidar observations. With a strong warming episode in the 1990s, the time series was least-square fitted to an 11-parameter nonlinear function. This yields a cooling trend starting from an insignificant value of 0.64 ± 0.99 K decade^-1 at 85 km, increasing to a maximum of 2.8 ± 0.58K decade^-1 between 91 and 93 km, and then decreasing to a warming trend above 103 km. The geographic altitude dependence of the trend is in general agreement with model predictions. …

Galaxy Zoo: Are Bars Responsible For The Feeding Of Active Galactic Nuclei At 0.2 < Z < 1.0?, Edmond Cheung, Jonathan R. Trump, E. Athanassoula, Steven P. Bamford, Eric F. Bell, A. Bosma, Carolin N. Cardamone, Kevin R. V. Casteels, S. M. Faber, Jerome J. Fang, Lucy F. Fortson, Dale D. Kocevski, David C. Koo, Seppo Laine, Chris Lintott, Karen L. Masters, Thomas Melvin, Robert C. Nichol, Kevin Schawinski, Brooke Simmons, Rebecca Smethurst, Kyle W. Willett

Physics and Astronomy Faculty Publications

We present a new study investigating whether active galactic nuclei (AGN) beyond the local universe are preferentially fed via large-scale bars. Our investigation combines data from Chandra and Galaxy Zoo: Hubble (GZH) in the AEGIS (All-wavelength Extended Groth strip International Survey), COSMOS (Cosmological Evolution Survey), and (Great Observatories Origins Deep Survey-South) GOODS-S surveys to create samples of face-on, disc galaxies at 0.2 < z < 1.0. We use a novel method to robustly compare a sample of 120 AGN host galaxies, defined to have 10⁴² erg s⁻¹ < L_X < 10⁴⁴ erg s⁻¹, with inactive control galaxies matched in stellar mass, rest-frame colour, size, Sérsic index, and redshift. Using the GZH bar classifications of each sample, we demonstrate that …

Deconstructing The Galaxy Stellar Mass Function With Ukidss And Candels: The Impact Of Colour, Structure And Environment, Alice Mortlock, Christopher J. Conselice, William G. Hartley, Ken Duncan, Caterina Lani, Jamie R. Owensworth, Omar Almaini, Arjen Van Der Wel, Kuang-Han Huang, Matthew L.N. Ashby, S. P. Willner, Adriano Fontana, Avishai Dekel, Anton M. Koekemoer, Harry C. Ferguson, Sandra M. Faber, Norman A. Grogin, Dale D. Kocevski

Physics and Astronomy Faculty Publications

We combine photometry from the Ultra Deep Survey (UDS), Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) UDS and CANDELS the Great Observatories Origins Deep Survey-South (GOODS-S) surveys to construct the galaxy stellar mass function probing both the low- and high-mass end accurately in the redshift range 0.3 < z < 3. The advantages of using a homogeneous concatenation of these data sets include meaningful measures of environment in the UDS, due to its large area (0.88 deg²), and the high-resolution deep imaging in CANDELS (H₁₆₀ > 26.0), affording us robust measures of structural parameters. We construct stellar mass functions for the entire sample as parametrized by the Schechter function, and find that there is a decline in the values of ϕ and of α with …

A Custom Battery For Operando Neutron Powder Diffraction Studies Of Electrode Structure, Wei Kong Pang, Vanessa Peterson

Australian Institute for Innovative Materials - Papers

Structure-property relations are central to understanding functional materials, and for battery research the use of neutron powder diffraction to reveal the atomistic and molecular-scale origin of battery performance characteristics is often essential. Although operando experiments of this kind are increasingly common as neutron sources and instrumentation advance, these experiments are hindered by the often large barrier presented by the preparation of whole batteries that yield a neutron diffraction signal from the electrode of interest that is sufficient to extract detailed structural information. This article presents a custom battery that is specifically designed for operando neutron powder diffraction. The battery is …

Flexible Free-Standing Graphene Paper With Interconnected Porous Structure For Energy Storage, Kewei Shu, Caiyun Wang, Sha Li, Chen Zhao, Yang Yang, Hua-Kun Liu, Gordon G. Wallace

Australian Institute for Innovative Materials - Papers

A novel porous graphene paper is prepared via freeze drying a wet graphene oxide gel, followed by thermal and chemical reduction. The macroscopic structure of the formed graphene paper can be tuned by the water content in the gel precursor. With 92% water content, an interconnected macroporous network can be formed. This porous graphene (PG) paper exhibits excellent electrochemical properties. It can deliver a high discharge capacity of 420 mA h g⁻¹ at a current density of 2000 mA g⁻¹ when used as binder-free lithium ion battery anode. PG paper exhibits a specific capacitance of 137 F g …

The Host Galaxies Of X-Ray Selected Active Galactic Nuclei To Z = 2.5: Structure, Star Formation, And Their Relationships From Candels And Herschel/Pacs, Dale D. Kocevski, D. J. Rosario, D. H. Mcintosh, A. Van Der Wel, J. Kartaltepe, P. Lang, P. Santini, S. Wuyts, D. Lutz, M. Rafelski, C. Villforth

Physics and Astronomy Faculty Publications

We study the relationship between the structure and star formation rate (SFR) of X-ray selected low and moderate luminosity active galactic nuclei (AGNs) in the two Chandra Deep Fields, using Hubble Space Telescope imaging from the Cosmic Assembly Near Infrared Extragalactic Legacy Survey (CANDELS) and deep far-infrared maps from the PEP+GOODS-Herschel survey. We derive detailed distributions of structural parameters and FIR luminosities from carefully constructed control samples of galaxies, which we then compare to those of the AGNs. At z ~ 1, AGNs show slightly diskier light profiles than massive inactive (non-AGN) galaxies, as well as modestly higher levels …

Enhanced Electron Lifetime Of Cdse/Cds Quantum Dot (Qd) Sensitized Solar Cells Using Znse Core-Shell Structure With Efficient Regeneration Of Quantum Dots, Rasin K. Ahmed, Long Zhao, Attila J. Mozer, Geoffrey D. Will, John M. Bell, Hongxia Wang

Australian Institute for Innovative Materials - Papers

Research on development of efficient passivation materials for high performance and stable quantum dot sensitized solar cells (QDSCs) is highly important. While ZnS is one of the most widely used passivation material in QDSCs, an alternative material based on ZnSe which was deposited on CdS/CdSe/TiO₂ photoanode to form a semi-core/shell structure has been found to be more efficient in terms of reducing electron recombination in QDSCs in this work. It has been found that the solar cell efficiency was improved from 1.86% for ZnSe0 (without coating) to 3.99% using 2 layers of ZnSe coating (ZnSe2) deposited by successive ionic …

The Effect Of Surface Passivation On The Structure Of Sulphur-Rich Pbs Colloidal Quantum Dots For Photovoltaic Application, Victor Malgras, Andrew Nattestad, Yusuke Yamauchi, S X. Dou, Jung Ho Kim

Australian Institute for Innovative Materials - Papers

The use of PbS colloidal quantum dots in photovoltaic devices is very promising because of their simple and low cost production processes and their unique properties, such as bandgap tunability and potential multiple exciton generation. Here we report the synthesis of PbS nanocrystals used for application in solar cells. The sulphur-rich nature of their surface appears to be caused by the exposure to ambient conditions. The use of methanol as medium during the ligand exchange process has a crucial role in the removal of native oleate ligands. Without proper ligand exchange, the unpassivated surface is subject to ambient hydroxylation leading …

Dual Yolk-Shell Structure Of Carbon And Silica-Coated Silicon For High-Performance Lithium-Ion Batteries, L Y. Yang, H Z. Li, Jun Liu, Ziqi Sun, S S. Tang, M Lei

Australian Institute for Innovative Materials - Papers

Silicon batteries have attracted much attention in recent years due to their high theoretical capacity, although a rapid capacity fade is normally observed, attributed mainly to volume expansion during lithiation. Here, we report for the first time successful synthesis of Si/void/SiO₂/void/C nanostructures. The synthesis strategy only involves selective etching of SiO₂ in Si/SiO₂/C structures with hydrofluoric acid solution. Compared with reported results, such novel structures include a hard SiO₂-coated layer, a conductive carbon-coated layer, and two internal void spaces. In the structures, the carbon can enhance conductivity, the SiO₂ layer has mechanically …

Improvement In Structure And Superconductivity Of Bulk Fese0.5te0.5 Superconductors By Optimizing Sintering Temperature, Ning Chen, Yongchang Liu, Zongqing Ma, Liming Yu, Huijun Li

Australian Institute for Innovative Materials - Papers

Sintering temperature plays a vital role in the evolution of phase structure and microstructure in polycrystalline FeSe0.5Te0.5 bulks fabricated by the two-step sintering method, and thus significantly influences their superconducting properties. Elevated sintering temperature (600-700°C) at second step facilitates the substitution of Te into the superconducting phase, which leads to the increased lattice distortion and thus contributes to the enhancement of superconductivity (the value of Tc reaches 15.6K). At the same time, the accelerated growth of the superconducting grains and the improved homogeneity motivated by elevated sintering temperature serve as the main reason for the sharp superconducting transition.

Role Of Anions On Structure And Pseudocapacitive Performance Of Metal Double Hydroxides Decorated With Nitrogen-Doped Graphene, Nasir Mahmood, Muhammad Nawaz Tahir, Asif Mahmood, Wenlong Yang, Xingxing Gu, Chuanbao Cao, Yawen Zhang, Yanglong Hou

Australian Institute for Innovative Materials - Papers

Electrochemical capacitors (EC) bear faster charge-discharge; however, their real applications are still on a long away due to lower capacitance and energy densities which mainly arise from simple surface charge accumulation or/and reaction. Here, a novel synthesis strategy was designed to obtain the purposeful hybrids of nickel cobalt double hydroxide (NiCoDH) with genetic morphology to improve their electrochemical performance as electrode of EC. Nanostructures of metal hydroxides were grown on t he nitrogen-doped graphene (NG) sheets by utilizing defects as nucleation sites and their composition was optimized both by tuning the ratio of Ni:Co as well as the counter halogen …

Split-Half-Tubular Polypyrrole@Sulfur@Polypyrrole Composite With A Novel Three-Layer-3d Structure As Cathode For Lithium/Sulfur Batteries, Xin Liang, Mingang Zhang, Mohammad Kaiser, Xuanwen Gao, Konstantin Konstantinov, Richard Tandiono, Zhaoxiang Wang, Hua-Kun Liu, S X. Dou, Jiazhao Wang

Australian Institute for Innovative Materials - Papers

Polypyrrole@Sulfur@Polypyrrole composite with a novel three-layer-3D-structure, which consists of an external polypyrrole coating layer, an intermediate sulfur filling layer, and an internal polypyrrole split-half-tube conducting matrix layer, has been synthesized by the oxidative chemical polymerization method and chemical precipitation method in this article. Due to this unique three-layer-structure, the discharge specific capacity of Polypyrrole@Sulfur@Polypyrrole composite cathode retained at 554mAh g-1 after 50 cycles, which represents 68.8% retention of the initial discharge specific capacity. In comparison, the Sulfur@Polypyrrole composite cathode, with the same components as Polypyrrole@Sulfur@Polypyrrole composite, but without the three-layer-structure, has the discharge specific capacity of 370mAh g-1 after 50 …

Electronic Structure And Photocatalytic Water Oxidation Activity Of Rtino2 (R = Ce, Pr And Nd) Perovskite Nitride Oxides, Spencer H. Porter, Zhenguo Huang, S X. Dou, Samantha Brown-Xu, Md. Golam Mahabub Sarwar, Roberto C. Myers, Patrick M. Woodward

Australian Institute for Innovative Materials - Papers

Three perovskite nitride oxides CeTiNO₂, PrTiNO₂, and NdTiNO₂ have been synthesized and their electronic structures and photocatalytic activities characterized and compared to LaTiNO₂. All three compounds have band gaps that fall in the range 2.0 − 2.1 eV, very similar to LaTiNO₂, which enables them to absorb a significant fraction of the visible spectrum. Photocatalytic oxygen evolution studies under visible light irradiation in the presence of a sacrificial electron acceptor (Ag⁺) show that the activity of NdTiNO₂ (16 μmol/g/hr) is comparable to that of LaTiNO₂ (17 μmol/g/hr), …