Materials Science and Engineering Commons^™

Determination Of Zirconium Oxide Chemistry Through Complementary Characterization Techniques, Corey M. Efaw, Reynolds Michael, Jordan L. Vandegrift, Kassiopeia Smith, Yaqiao Wu, Brian J. Jaques, Hongqiang Hu, Claire Xiong, Michael F. Hurley

Materials Science and Engineering Faculty Publications and Presentations

Nuclear energy has been increasingly recognized as an effective and low carbon-emission energy source. Nuclear reactors are susceptible to adverse effects, which can lead to potentially severe consequences, though they are low in probability. To ensure safety and improved monitoring of reactors, there have been increasing interests in developing sensors to monitor key parameters relating to the status within a reactor. In order to improve sensor accuracy, high-resolution characterization of cladding materials can be utilized to correlate with sensor output. A common issue with zirconium cladding is the so-called "breakaway phenomenon", a critical factor seen as the transition from an …

Anomalous Stranski-Krastanov Growth Of (111)-Oriented Quantum Dots With Tunable Wetting Layer Thickness, Christopher F. Schuck, Simon K. Roy, Trent Garrett, Paul J. Simmonds

Materials Science and Engineering Faculty Publications and Presentations

Driven by tensile strain, GaAs quantum dots (QDs) self-assemble on In_0.52Al_0.48As(111)A surfaces lattice-matched to InP substrates. In this study, we show that the tensile-strained self-assembly process for these GaAs(111)A QDs unexpectedly deviates from the well-known Stranski-Krastanov (SK) growth mode. Traditionally, QDs formed via the SK growth mode form on top of a flat wetting layer (WL) whose thickness is fixed. The inability to tune WL thickness has inhibited researchers’ attempts to fully control QD-WL interactions in these hybrid 0D-2D quantum systems. In contrast, using microscopy, spectroscopy, and computational modeling, we demonstrate that for GaAs(111)A QDs, we …

Characterization Of Zirconium Oxides Part I: Raman Mapping And Spectral Feature Analysis, Corey M. Efaw, Jordan L. Vandegrift, Michael Reynolds, Samuel Mcmurdie, Brian J. Jaques, Hui Xiong, Michael F. Hurley

Materials Science and Engineering Faculty Publications and Presentations

Raman mapping of sectioned zirconium cladding oxides was performed to analyze different spectral features before and after breakaway, as well as between zirconium and its alloys Zr-2.65Nb, Zry-3, and Zry-4. Oxide phase composition, or percent tetragonality, was defined to compare tetragonal to monoclinic zirconia. Percent tetragonality was spatially mapped to support distinction of zirconia phase distribution. A tetragonal-rich layer was seen at the metal/oxide interface, while post-breakaway samples exhibited increased amount of tetragonal phase in the bulk of their oxides. Spatial mapping of spectral peak location and half-width at half-maximum was accomplished to distinguish differences in stability mechanisms of tetragonal-rich …

Machine Learning Predictions Electronic Couplings For Charge Transport Calculations Of P3ht, Evan D. Miller, Matthew L. Jones, Mike M. Henry, Bryan Stanfill, Eric Jankowski

Materials Science and Engineering Faculty Publications and Presentations

The purpose of this work is to lower the computational cost of predicting charge mobilities in organic semiconductors, which will benefit the screening of candidates for inexpensive solar power generation. We characterize efforts to minimize the number of expensive quantum chemical calculations we perform by training machines to predict electronic couplings between monomers of poly-(3-hexylthiophene). We test five machine learning techniques and identify random forests as the most accurate, information-dense, and easy-to-implement approach for this problem, achieving mean-absolute-error of 0.02 [× 1.6 × 10⁻¹⁹ J], R² = 0.986, predicting electronic couplings 390 times faster than quantum chemical calculations, …

Oxidation Behavior Of Welded Zry-3, Zry-4, And Zr–1nb Tubes, Jordan Vandegrift, Clemente J. Parga, Ben Coryell, Darryl P. Butt, Brian J. Jaques

Materials Science and Engineering Faculty Publications and Presentations

The Transient Reactor Test (TREAT) facility is a research reactor designed to simulate rapid transients to test new fuel designs. TREAT's cladding is exposed to unique conditions compared to normal water reactors. These conditions include: exposure to air at high temperatures (≥600 °C), rapid heating (≈700 °^C/_s), and cladding geometry that includes chamfers and welds. This work investigates the effects of chamfering and welding on the oxidation behavior of zirconium alloys (Zircaloy-3, Zircaloy-4, and Zr–1Nb). Tube specimens were examined under isothermal and transient conditions in dry and humid air. The effect of weld type (tungsten inert …

A Parametric Study For In-Pile Use Of The Thermal Conductivity Needle Probe Using A Transient, Multilayered Analytical Model, Courtney Hollar, Austin Fleming, Kurt Davis, Ralph Budwig, Colby Jensen, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

By utilizing an in-pile measurement, thermal conductivity can be determined under prototypic conditions over a range of burnup. In this work we develop a multilayer quadrupoles analytical model to describe the transient thermal interactions between a line heat source (i.e. needle probe) and cylindrical nuclear fuel geometry for inpile thermal conductivity measurements. A finite element analysis of the detailed needle probe geometry was compared to results from the analytical model to verify the assumptions made in the analytical model. Experimentally, the needle probe was used to measure the thermal properties of polytetrafluoroethylene (PTFE) and stainless steel 304 with three different …

Utilizing A Single Silica Nanospring As An Insulating Support To Characterize The Electrical Transport And Morphology Of Nanocrystalline Graphite, David Estrada, Paul H. Davis, Twinkle Pandhi

Materials Science and Engineering Faculty Publications and Presentations

A graphitic carbon, referred to as graphite from the University of Idaho thermolyzed asphalt reaction (GUITAR), was coated in silica nanosprings and silicon substrates via the pyrolysis of commercial roofing tar at 800 °C in an inert atmosphere. Scanning electron microscopy and transmission electron microscopy images indicate that GUITAR is an agglomeration of carbon nanospheres formed by the accretion of graphitic flakes into a ~100 nm layer. Raman spectroscopic analyses, in conjunction with scanning electron microscopy and transmission electron microscopy, indicate that GUITAR has a nanocrystalline structure consisting of ~1–5 nm graphitic flakes interconnected by amorphous sp³ bonded carbon. …

Inas(111)A Homoepitaxy With Molecular Beam Epitaxy, Kevin D. Vallejo, Trent A. Garrett, Kathryn E. Sautter, Kevin Saythavy, Baolai Liang, Paul J. Simmonds

Materials Science and Engineering Faculty Publications and Presentations

The authors have established a robust set of growth conditions for homoepitaxy of high-quality InAs with a (111)A crystallographic orientation by molecular beam epitaxy (MBE). By tuning the substrate temperature, the authors obtain a transition from a 2D island growth mode to step-flow growth. Optimized MBE parameters (substrate temperature = 500 °C, growth rate = 0.12ML/s, and V/III ratio ≥ 40) lead to the growth of extremely smooth InAs(111)A films, free from hillocks and other 3D surface imperfections. The authors see a correlation between InAs surface smoothness and optical quality, as measured by photoluminescence spectroscopy. This work establishes InAs(111)A as …

A Simple Method To Characterize High Rate Twin Boundary Kinetics In Ni-Mn-Ga, Bibek Karki, Peter Müllner

Materials Science and Engineering Faculty Publications and Presentations

Experimental characterization of twin boundary kinetics is essential to systematically test and reproduce the actuation properties of Magnetic Shape Memory (MSM) elements at high rates. Here, we present a simple, nondestructive, experimental method to quantify the dynamic response of an MSM crystal and extract the major material properties that govern its kinetics. The tested sample is subjected to a mechanical pulse that is produced by a simple off-the-shelf solenoid. The mechanical pulse leads to actuation of the tested MSM Ni–Mn–Ga single crystal within 10 ms, during which the twin boundary velocity varies between zero and 2 m/s. The displacement and …

Implementing Population-Based Mass Drug Administration For Malaria: Experience From A High Transmission Setting In North Eastern Uganda, Richard Elliott

Materials Science and Engineering Faculty Publications and Presentations

Background: Mass drug administration (MDA) is a suggested mean to accelerate efforts towards elimination and attainment of malaria-free status. There is limited evidence of suitable methods of implementing MDA programme to achieve a high coverage and compliance in low-income countries. The objective of this paper is to assess the impact of this MDA delivery strategy while using coverage measured as effective population in the community and population available.

Methods: Population-based MDA was implemented as a part of a larger program in a high transmission setting in Uganda. Four rounds of interventions were implemented over a period of 2 years at …

Oxidation Behavior Of Zirconium, Zircaloy-3, Zircaloy-4, Zr-1nb, And Zr- 2.5nb In Air And Oxygen, Jordan L. Vandegrift, Patrick M. Price, John-Paul Stroud, Clemente J. Parga, Isabella J. Van Rooyen, Brian J. Jaques, Darryl P. Butt

Materials Science and Engineering Faculty Publications and Presentations

The Transient Reactor Test (TREAT) facility at the Idaho National Laboratory currently utilizes a legacy Zircaloy- 3 cladding, which is no longer commercially available. TREAT is air cooled and routinely operates at temperatures well above that of traditional reactor designs. This study investigates the oxidation behavior of pure zirconium and its alloys (Zircaloy-3, Zircaloy-4, Zr-1Nb, Zr-2.5Nb) in Ar+20%O₂ and N₂+20%O₂ atmospheres at temperatures ranging from 400–800 °C to determine which alloy should be implemented as TREAT's cladding. While the oxidation behavior of zirconium based cladding materials has been extensively documented, this study focuses on direct comparison …

Lessons Learned About Building An Assertive Community, Donna C. Llewellyn, William L. Hughes, Megan F. Gambs

Materials Science and Engineering Faculty Publications and Presentations

One of our observations in this lessons learned paper is that there is underwhelming faculty development related to scholarship other than on how to submit and sometimes how to write proposals. This de facto service model misses everything outside of the proposal-writing process; which is the least important, but is often the most celebrated, rewarded, and supported phase. Inspired by national Centers for Teaching & Learning, and modeled after the emerging Communities of Transformation literature, we are piloting a Center for Transformative Research at Boise State University. The vision of our Center is to build and sustain an ASSERTive community …

Voices Of Our Students: Using Evidence-Based Methods To Inform A Multidisciplinary Engineering Program Design, Vicki Stieha, Noah Salzman, Amy J. Moll

Materials Science and Engineering Faculty Publications and Presentations

Listening carefully to our students and integrating the variables that matter to them is a step that we can take to increase the number of women and underrepresented minority graduates in engineering. This paper shares an evaluative case study as we report findings from data gathering tools guiding our continuous improvement process. The findings illuminate students’ perceptions of their engineering design course and curriculum. We conclude by discussing the pedagogical decisions the teaching team is making as a result of listening to our students’ voices.

Synergy And Timing: A Concurrent Mass Medical Campaign Predicted To Augment Indoor Residual Spraying For Malaria, Richard C. Elliott, David L. Smith, Dorothy C. Echodu

Materials Science and Engineering Faculty Publications and Presentations

Background: Control programmes for high burden countries are tasked with charting effective multi-year strategies for malaria control within significant resource constraints. Synergies between different control tools, in which more than additive benefit accrues from interventions used together, are of interest because they may be used to obtain savings or to maximize health impact per expenditure. One commonly used intervention in sub-Saharan Africa is indoor residual spraying (IRS), typically deployed through a mass campaign. While possible synergies between IRS and long-lasting insecticide-treated nets (LLINs) have been investigated in multiple transmission settings, coordinated synergy between IRS and other mass medical distribution campaigns …

Thermal Transport In Layer-By-Layer Assembled Polycrystalline Graphene Films, David Estrada, Alondra Perez

Materials Science and Engineering Faculty Publications and Presentations

New technologies are emerging which allow us to manipulate and assemble 2-dimensional (2D) building blocks, such as graphene, into synthetic van der Waals (vdW) solids. Assembly of such vdW solids has enabled novel electronic devices and could lead to control over anisotropic thermal properties through tuning of inter-layer coupling and phonon scattering. Here we report the systematic control of heat flow in graphene-based vdW solids assembled in a layer-by-layer (LBL) fashion. In-plane thermal measurements (between 100 K and 400 K) reveal substrate and grain boundary scattering limit thermal transport in vdW solids composed of one to four transferred layers of …

Roadmap On Biological Pathways For Electronic Nanofabrication And Materials, Reza M. Zadegan

Materials Science and Engineering Faculty Publications and Presentations

Conventional microchip fabrication is energy and resource intensive. Thus, the discovery of new manufacturing approaches that reduce these expenditures would be highly beneficial to the semiconductor industry. In comparison, living systems construct complex nanometer-scale structures with high yields and low energy utilization. Combining the capabilities of living systems with synthetic DNA-/protein-based self-assembly may offer intriguing potential for revolutionizing the synthesis of complex sub-10 nm information processing architectures. The successful discovery of new biologically based paradigms would not only help extend the current semiconductor technology roadmap, but also offer additional potential growth areas in biology, medicine, agriculture and sustainability for the …

Corrosion Initiation And Propagation On Carburized Martensitic Stainless Steel Surfaces Studied Via Advanced Scanning Probe Microscopy, Armen Kvryan, Corey M. Efaw, Kari A. Higginbotham, Olivia O. Maryon, Paul H. Davis, Elton Graugnard, Michael F. Hurley

Materials Science and Engineering Faculty Publications and Presentations

Historically, high carbon steels have been used in mechanical applications because their high surface hardness contributes to excellent wear performance. However, in aggressive environments, current bearing steels exhibit insufficient corrosion resistance. Martensitic stainless steels are attractive for bearing applications due to their high corrosion resistance and ability to be surface hardened via carburizing heat treatments. Here three different carburizing heat treatments were applied to UNS S42670: a high-temperature temper (HTT), a low-temperature temper (LTT), and carbo-nitriding (CN). Magnetic force microscopy showed differences in magnetic domains between the matrix and carbides, while scanning Kelvin probe force microscopy (SKPFM) revealed a 90–200 …

Open-Source Automated Chemical Vapor Deposition System For The Production Of Two-Dimensional Nanomaterials, Lizandra Williams-Godwin, Dale Brown, Richard Livingston, Tyler Webb, Lynn Karriem, Elton Graugnard, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

The study of two- dimensional (2D) materials is a rapidly growing area within nanomaterials research. However, the high equipment costs, which include the processing systems necessary for creating these materials, can be a barrier to entry for some researchers interested in studying these novel materials. Such process systems include those used for chemical vapor deposition, a preferred method for making these materials. To address this challenge, this article presents the first open-source design for an automated chemical vapor deposition system that can be built for less than a third of the cost for a comparable commercial system. The materials and …

Fabrication Of Stoichiometric U3Si2 Fuel Pellets, Adrian R. Wagner, Jason M. Harp, Kip E. Archibald, Seth C. Ashby, Jennifer K. Watkins, Kevin R. Tolman

Materials Science and Engineering Faculty Publications and Presentations

Uranium silicide, U₃Si₂, is an accident tolerant fuel type which is gaining momentum as a replacement fuel for uranium dioxide (UO₂). Idaho National Laboratories has been fabricating phase pure U₃Si₂ fuel pellets for use in various irradiation and material characterization experiments. Stoichiometric U₃Si₂ fuel pellets were fabricated using a powder metallurgy and arcmelting technique. The use of the stoichiometric ratio to alloy uranium and silicon, and sintering in a vacuum environment allowed for the fabrication of high density (>94% theoretical density), phase pure pellets, greater than 94% …

Toward Improving Ambient Volta Potential Measurements With Skpfm For Corrosion Studies, Corey M. Efaw, Thiago Da Silva, Paul H. Davis, Lan Li, Elton Graugnard, Michael F. Hurley

Materials Science and Engineering Faculty Publications and Presentations

Scanning Kelvin probe force microscopy (SKPFM) is used in corrosion studies to quantify the relative nobility of different microstructural features present within complex metallic systems and thereby elucidate possible corrosion initiation sites. However, Volta potential differences (VPDs) measured via SKPFM in the literature for metal alloys exhibit large variability, making interpretation and application for corrosion studies difficult. We have developed an improved method for referencing SKPFM VPDs by quantifying the closely related work function of the probe relative to an inert gold standard whose modified work function is calculated via density functional theory (DFT). By measuring and tracking changes in …

Optimization And Validation Of Efficient Models For Predicting Polythiophene Self-Assembly, Evan D. Miller, Matthew L. Jones, Michael M. Henry, Paul Chery, Kyle Miller, Eric Jankowski

Materials Science and Engineering Faculty Publications and Presentations

We develop an optimized force-field for poly(3-hexylthiophene) (P3HT) and demonstrate its utility for predicting thermodynamic self-assembly. In particular, we consider short oligomer chains, model electrostatics and solvent implicitly, and coarsely model solvent evaporation. We quantify the performance of our model to determine what the optimal system sizes are for exploring self-assembly at combinations of state variables. We perform molecular dynamics simulations to predict the self-assembly of P3HT at ~350 combinations of temperature and solvent quality. Our structural calculations predict that the highest degrees of order are obtained with good solvents just below the melting temperature. We find our model produces …

Tying Together Multiscale Calculations For Charge Transport In P3ht: Structural Descriptors, Morphology, And Tie-Chains, Evan D. Miller, Matthew L. Jones, Eric Jankowski

Materials Science and Engineering Faculty Publications and Presentations

Evaluating new, promising organic molecules to make next-generation organic optoelectronic devices necessitates the evaluation of charge carrier transport performance through the semi-conducting medium. In this work, we utilize quantum chemical calculations (QCC) and kinetic Monte Carlo (KMC) simulations to predict the zero-field hole mobilities of ~100 morphologies of the benchmark polymer poly(3-hexylthiophene), with varying simulation volume, structural order, and chain-length polydispersity. Morphologies with monodisperse chains were generated previously using an optimized molecular dynamics force-field and represent a spectrum of nanostructured order. We discover that a combined consideration of backbone clustering and system-wide disorder arising from side-chain conformations are correlated with …

Magnetic And Electrocatalytic Properties Of Transition Metal Doped Mos2 Nanocrystals, Karthik Chinnathambi

Materials Science and Engineering Faculty Publications and Presentations

In this paper, the magnetic and electrocatalytic properties of hydrothermally grown transition metal doped (10% of Co, Ni, Fe, and Mn) 2H-MoS₂ nanocrystals (NCs) with a particle size 25–30 nm are reported. The pristine 2H-MoS₂ NCs showed a mixture of canted anti-ferromagnetic and ferromagnetic behavior. While Co, Ni, and Fe doped MoS₂ NCs revealed room temperature ferromagnetism, Mn doped MoS₂ NCs showed room temperature paramagnetism, predominantly. The ground state of all the materials is found to be canted-antiferromagnetic phase. To study electrocatalytic performance for hydrogen evolution reaction, polarization curves were measured for undoped and the doped …

Carbon-Coated Fep Nanoparticles Anchored On Carbon Nanotube Networks As Anode For Long-Life Sodium-Ion Storage, Chunrong Ma, Zhengguang Fu, Changjian Deng, Xiaozhen Liao, Yushi He, Zifeng Ma, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

A novel electrode design strategy of carbon-coated FeP particles anchored on a conducting carbon nanotube network (CNT@FePC) is designed to achieve a superior sodium ion storage. Such a unique structure demonstrated excellent long-life cycling stability (a 95% capacity retention for more than 1200 cycles at 3 A g^-1) and rate capability (delivered 272 mAh g^-1 at 8 A g^-1).

Using Graphs To Quantify Energetic And Structural Order In Semicrystalline Oligothiophene Thin Films, Ellen Van, Matthew Jones, Eric Jankowski, Olga Wodo

Materials Science and Engineering Faculty Publications and Presentations

In semicrystalline conjugated polymer thin films, the mobility of charges depends on the arrangement of the individual polymer chains. In particular, the ordering of the polymer backbones affects the charge transport within the film, as electron transfer generally occurs along the backbones with alternating single and double bonds. In this paper, we demonstrate that polymer ordering should be discussed not only in terms of structural but also energetic ordering of polymer chains. We couple data from molecular dynamics simulations and quantum chemical calculations to quantify both structural and energetic ordering of polymer chains. We leverage a graph-based representation of the …

Boron-Implanted Silicon Substrates For Physical Adsorption Of Dna Origami, Sadao Takabayashi, Shohei Kotani, Juan Flores-Estrada, Elijah Spears, Jennifer E. Padilla, Lizandra C. Godwin, Elton Graugnard, Wan Kuang, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

DNA nanostructures routinely self-assemble with sub-10 nm feature sizes. This capability has created industry interest in using DNA as a lithographic mask, yet with few exceptions, solution-based deposition of DNA nanostructures has remained primarily academic to date. En route to controlled adsorption of DNA patterns onto manufactured substrates, deposition and placement of DNA origami has been demonstrated on chemically functionalized silicon substrates. While compelling, chemical functionalization adds fabrication complexity that limits mask efficiency and hence industry adoption. As an alternative, we developed an ion implantation process that tailors the surface potential of silicon substrates to facilitate adsorption of DNA nanostructures …

Structural Evolution Of Molybdenum Disulfide Prepared By Atomic Layer Deposition For Realization Of Large Scale Films In Microelectronic Applications, Steven Letourneau, Elton Graugnard

Materials Science and Engineering Faculty Publications and Presentations

Molybdenum disulfide (MoS₂) films are attractive materials for electronic and optoelectronic devices, but the temperatures used in the chemical vapor deposition (CVD) of these materials are too high for device integration. Recently, a low-temperature atomic layer deposition (ALD) process was demonstrated for growth of MoS₂ films at 200 °C using MoF₆ and H₂S. However, the as-deposited films were amorphous and required annealing to obtain the desired layered structure. The MoS₂ films were sulfur-deficient; however, after annealing the crystallinity improved. To study the structure of these films and the process by which they crystallize, …

Electropolishing Valve Metals With A Sulfuric Acid-Methanol Electrolyte At Low Temperature, Pete Barnes, Andreas Savva, Kiev Dixon, Hailey Bull, Laura Rill, Devan Karsann, Sterling Croft, Jesse Schimpf, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

This study reports the electropolishing Ti and Nb metals using a fluoride-free electrolyte of sulfuric acid and methanol at low temperature (-70°C) without prior treatment. A fluoride-free electrolyte provides a less hazardous and more environmentally friendly option for electropolishing procedure. Experimental studies are presented on electropolishing with sulfuric acid electrolyte, which provides high quality macro- and micro-smoothing of the metal surfaces. Optimal conditions yielded leveling and brightening of the surface of Ti and Nb metals beyond that of the currently utilized electropolishing procedures with fluoride-containing electrolytes. The root mean squared roughness (R_q) from atomic force microscopy (AFM) …

Electronic Structure, Pore Size Distribution, And Sorption Characterization Of An Unusual Mof, {[Ni(Dpbz)][Ni(Cn)4]}N, Dpbz = 1,4-Bis(4-Pyridyl)Benzene, Winnie Wong-Ng, Izaak Williamson, Matthew Lawson, Daniel W. Siderus, Jeffrey T. Culp, Yu-S. Chen, Lan Li

Materials Science and Engineering Faculty Publications and Presentations

The monoclinic (Ni(L)[Ni(CN)₄] (L= 1,4-Bis(4-pyridyl) benzene) compound (defined as Ni-dpbz) is a flexible metal organic framework which assumes a pillared structure with layers defined by 2D Ni[Ni(CN)₄]_n nets and dpbz ligands as pillars. The structure features an entrapped dpbz ligand that links between the open ends of four-fold Ni sites from two neighboring chains. This arrangement results in an unusual 5-fold pseudo square-pyramid environment for Ni and a significantly long Ni-N distance of 2.369(4) Å. Using Density Functional Theory calculations, the different bonding characteristics between the 5-fold and 6-fold Ni's were determined. We found that …

The Redshirt In Engineering Consortium: Progress And Early Insights, Janet Callahan, Donna C. Llewellyn, Ann E. Delaney

Materials Science and Engineering Faculty Publications and Presentations

The NSF-funded Redshirt in Engineering Consortium was formed in 2016 with the goal of enhancing the ability of academically talented but underprepared students coming from lowincome backgrounds to successfully graduate with engineering degrees. The Consortium takes its name from the practice of redshirting in college athletics, with the idea of providing an extra year and support to help promising engineering students complete a bachelor’s degree. The Consortium builds on the success of three existing “academic redshirt” programs and expands the model to three new schools. The Existing Redshirt Institutions (ERIs) help mentor and train the new Student Success Partners (SSPs), …