Publications

Defective Ribonucleoproteins, Mistakes in RNA Processing, and Diseases

by Mihailovic, MK; Chen, A; Gonzalez-Rivera, JC; Contreras, LM

BIOCHEMISTRY; Volume: 56; Issue: 10; Pages: 1367-1382; DOI: 10.1021/acs.biochem.6b01134; Published: MAR 14 2017

Ribonucleoproteins (RNPs) are vital to many cellular events. To this end, many neurodegenerative diseases and cancers have been linked to RNP malfunction, particularly as this relates to defective processing of cellular RNA. The connection of RNPs and diseases has also propagated a shift of focus onto RNA targeting from traditional protein targeting treatments. However, therapeutic development in this area has been limited by incomplete molecular insight into the specific contributions of RNPs to disease. This review outlines the role of several RNPs in diseases, focusing on molecular defects in processes that affect proper RNA handling in the cell. This work also evaluates the contributions of recently developed methods to understanding RNP association and function. We review progress in this area by focusing on molecular malfunctions of RNPs associated with the onset and progression of several neurodegenerative diseases and cancer and conclude with a brief discussion of RNA-based therapeutic efforts.

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Flexible CuInSe2 Nanocrystal Solar Cells on Paper

by Voggu, VR; Sham, J; Pfeffer, S; Pate, J; Fillip, L; Harvey, TB; Brown, RM; Korgel, BA

ACS ENERGY LETTERS; Volume: 2; Issue: 3; Pages: 574-581; DOI: 10.1021/acsenergylett.7b00001; Published: MAR 2017

Solar cells on paper have the potential to be inexpensive and portable due to several unique features of the substrate: paper is cheap, flexible, lightweight, biodegradable, and manufactured by roll-to-roll processing. Here, we report the first nanocrystal photovoltaic devices (PVs) made on 2 paper. Using spray-deposited CuInSe2 nanocrystals as the absorber material on substrates composed of bacterial CL) hansenii, these devices demonstrate excep-d cellulose nanofibers synthesized by the microorganism exceptional electrical and mechanical integrity. There is no significant loss in PV device performance after more than 100 flexes to 5 mm radius, and the devices continue to perform when folded into a crease. The practical use of these paper PVs is demonstrated with a prototype device powering liquid crystal displays (LCDs) mounted to various kinds of

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A review on wall slip in high solid dispersions

by Cloitre, M; Bonnecaze, RT

RHEOLOGICA ACTA; Volume: 56; Issue: 3; Pages: 283-305; DOI: 10.1007/s00397-017-1002-7; Published: MAR 2017

High solid dispersions are soft materials made of colloidal or non-colloidal particles dispersed at high volume fractions in a liquid matrix. They include hard sphere glasses, colloidal pastes, concentrated emulsions, foams, and vesicles. These materials are prone to exhibit different kinds of flow heterogeneities: shear banding, wall slip, and fracture. While wall slip is often considered as a nuisance by experimentalists, it appears to be a fundamental component to the way that high solid dispersions respond to mechanical deformation. Moreover, the ability of soft materials to slip onto surfaces allows them to move readily and efficiently in many natural phenomena and industrial processes. This review surveys recent developments and current research in the field. Topics like wall slip detection and control, microscopic modeling for rigid and soft particles materials, and the relation between wall slip and other flow heterogeneities are discussed. We also identify important open issues for future research.

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Development and analysis of residential change-point models from smart meter data

by Perez, KX; Cetin, K; Baldea, M; Edgar, TF

ENERGY AND BUILDINGS; Volume: 139; Pages: 351-359; DOI: 10.1016/j.enbuild.2016.12.084; Published: MAR 15 2017

As access to residential energy use data becomes more widely available, it is possible to identify significant energy consumers and provide guidance on mitigating such large loads. In hotter climates, such as Texas, air-conditioning (AC) systems are important contributors to overall residential electricity demand. Providing a quick, simple and effective framework to describe and compare electricity demand patterns between different hotises is valuable to identify potential candidates fot peak load reduction and overall energy use mitigation. In this study, we evaluate the application of daily change-point models to describe the demand patterns of residential AC systems for 45 actual houses in Austin, TX during 2013. While previous research regarding change -point models has been focused on monthly data for commercial buildings, this study extends its application to daily residential energy use. The resulting models describe a behavior where energy consumption with relation to outdoor dry-bulb temperature is negligible up until a change -point, after which AC energy use increases linearly and results in an “energy slope.” An analysis of the neighborhood shows the distribution of the AC “energy slopes” is left-skewed and centered on 0.08 kW per degrees C dry bulb temperature. Energy audit information found eight house characteristics to be correlated with a higher energy slope. A subsequent parametric analysis using data from the energy simulation software BEopt confirmed the direction of the correlation. This work provides a screening tool to compare energy demand patterns of houses and target houses with the largest magnitude of energy slopes for future energy audits. (C)2016 Published by Elsevier B.V.

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In Situ Growth of Fe(Ni) OOH Catalyst on Stainless Steel for Water Oxidation

by Tang, D; Mabayoje, O; Lai, YQ; Liu, YX; Mullins, CB

CHEMISTRYSELECT; Volume: 2; Issue: 7; Pages: 2230-2234; DOI: 10.1002/slct.201700081; Published: MAR 2017

Stainless steel contains the elements Fe, Ni, Cr and Mn, which are known as active centers of oxygen evolution reaction (OER) catalysts. The high conductivity of stainless steel also makes it an ideal substrate for OER. These facts imply that stainless steel should be a suitable candidate as an OER electrode. Here, we report a simple solution treatment approach that enables stainless steel to be an efficient and stable OER electrode. It was found that a uniform brown film with highly rippled sheet structure could be in situ grown on stainless steel at room temperature by immersing it in an alkaline oxidant solution containing NaOH and (NH4) 2S2O8. The composition of the brown film was found to include Fe(Ni) OOH by Raman and Xray photoelectron spectroscopy (XPS) analyses. In 1 M KOH electrolyte, the prepared OER electrode exhibited good electrocatalytic performance with a relatively low overpotential of 300 mV at a benchmark current density of 10 mA/cm(2) and a small Tafel slope of 34 mV/decade. Moreover, this OER electrode showed excellent long-term stability. This work highlights the possibility of potentially converting accessible materials into useful catalysts through simple chemical treatments.

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Inkjet-Printed Lithium-Sulfur Microcathodes for All-Printed, Integrated Nanomanufacturing

by Milroy, CA; Jang, S; Fujimori, T; Dodabalapur, A; Manthiram, A

SMALL, Volume: 13, Issue: 11, Article Number: UNSP 1603786, DOI: 10.1002/smll.201603786, Published: MAR 21 2017

Improved thin-film microbatteries are needed to provide appropriate energy-storage options to power the multitude of devices that will bring the proposed “Internet of Things” network to fruition (e.g., active radio-frequency identification tags and microcontrollers for wearable and implantable devices). Although impressive efforts have been made to improve the energy density of 3D microbatteries, they have all used low energy-density lithium-ion chemistries, which present a fundamental barrier to miniaturization. In addition, they require complicated microfabrication processes that hinder cost-competitiveness. Here, inkjet-printed lithium-sulfur (Li-S) cathodes for integrated nanomanufacturing are reported. Single-wall carbon nanotubes infused with electronically conductive straight-chain sulfur (S@SWNT) are adopted as an integrated current-collector/active-material composite, and inkjet printing as a top-down approach to achieve thin-film shape control over printed electrode dimensions is used. The novel Li-S cathodes may be directly printed on traditional microelectronic semicoductor substrates (e.g., SiO2) or on flexible aluminum foil. Profilometry indicates that these microelectrodes are less than 10 mu m thick, while cyclic voltammetry analyses show that the S@SWNT possesses pseudocapacitive characteristics and corroborates a previous study suggesting the S@SWNT discharge via a purely solid-state mechanism. The printed electrodes produce approximate to 800 mAh g(-1) S initially and approximate to 700 mAh g(-1) after 100 charge/discharge cycles at C/2 rate.

Keywords

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Colloidal Monolayer beta-In2Se3 Nanosheets with High Photoresponsivity

by Almeida, G; Dogan, S; Bertoni, G; Giannini, C; Gaspari, R; Perissinotto, S; Krahne, R; Ghosh, S; Manna, L

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Volume: 139, Issue: 8, Pages: 3005-3011, DOI: 10.1021/jacs.6b11255, Published: MAR 1 2017

We report a low-temperature colloidal synthesis of single-layer, five-atom-thick, beta-In2Se3 nanosheets with lateral sizes tunable from similar to 300 to similar to 900 nm, using short aminonitriles (dicyandiamide or cyanamide) as shape controlling agents. The phase and the monolayer nature of the nanosheets were ascertained by analyzing the intensity ratio between two diffraction peaks from two-dimensional slabs of the various phases, determined by diffraction simulations. These findings were further backed-up by comparing and fitting the experimental X-ray diffraction pattern with Debye formula simulated patterns and with side-view high-resolution transmission electron microscopy imaging and simulation. The beta-In2Se3 nanosheets were found to be indirect band gap semiconductors (E-g = 1.55 eV), and single nanosheet photodetectors demonstrated high photoresponsivity and fast response times.

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Large area fabrication of graphene nanoribbons by wetting transparency-assisted block copolymer lithography

by Katsumata, R; Yogeesh, MN ; Wong, HL; Zhou, SX ; Sirard, SM; Huang, T; Piner, RD; Li, W; Lee, AL; Carlson, MC; Maher, MJ; Akinwande, D; Ellison, CJ

POLYMER, Volume: 110, Pages: 131-138, DOI: 10.1016/j.polymer.2016.12.034, Published: FEB 10 2017

Patterning graphene into nanoribbons (graphene nanoribbons, GNR) allows for tunability in the emerging fields of plasmonic devices in the mid-infrared and terahertz regime. However, the fabrication processes of GNR arrays for plasmonic devices often include a low-throughput electron beam lithography step that cannot be easily scaled to large areas. In this study, we developed a GNR fabrication method using block copolymer (BCP) lithography that takes advantage of the wetting transparency of graphene. One major advantage of this method is that the self-assembled domains of the polystyrene-block-poly(methyl methacrylate) BCP are oriented perpendicularly directly on top of the graphene where they can later serve as an etch mask. Large area (cm(2) scale, 3 mu m x 3 gm defect-free area) 13-51 nm wide GNR arrays were successfully fabricated using this scalable protocol. This wetting transparency-assisted GNR fabrication method could be useful for high-throughput production of various plasmonic devices, including biosensors, and photodetectors. (C) 2016 Elsevier Ltd. All rights reserved.

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Sacrificial crystal templating of hyaluronic acid-based hydrogels

by Thomas, RC; Chung, PE; Modi, SP; Hardy, JG ; Schmidt, CE

EUROPEAN POLYMER JOURNAL; Volume: 87; Pages: 487-496; DOI: 10.1016/j.eurpolymj.2016.10.022; Published: FEB 2017

Natural tissues have intricate structures organized in a hierarchical fashion over multiple length scales (A to cm). These tissues commonly incorporate pores as a key feature that may regulate cell behavior. To enable the development of tissues scaffolds with biomimetic pore structures, it is important to investigate methods to impart pores to biomaterials, such as the use of novel sacrificial porogens. Here we report the use of sacrificial crystals to impart pores to biopolymer hydrogels (based on a methacrylated hyaluronic acid derivative) with macroscopic crystal templated pores embedded within them. The pore structure was investigated using microscopy (cryoSEM and confocal), and the specific sacrificial porogen used was found not only to impact the pore structure, but also swelling and mechanical properties. Such templated hydrogels have prospects for application as instructive tissue scaffolds (where the pore structure controls cell alignment, migration, etc.). (C) 2016 Elsevier Ltd. All rights reserved.

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