A New Materials and Design Approach for Roads, Bridges, Pavement, and Concrete

Increased understanding of demand for transport energy and how to improve road pavement materials would enable decision makers to make environmental, financial, and other positive changes in future planning and design of roads, bridges, and other important transportation structures. This research comprises three studies focused on pavement materials and a fourth study that examines energy demand within the road transportation sector. These studies are as follows: 1. A techno-economic study of ground tire rubber as an asphalt modifier; 2. A computational fluid dynamics analysis comparing the urban heat island effect of two different pavement materials – asphalt and Portland Cement Concrete; 3. A new approach that modifies the surface of ground tire rubber using low-cost chemicals and treatment methods to be used in asphalt applications; and 4. Analysis of road transport energy demand in California and the United States. The findings of these studies include that 1. GTR is an effective and economically suitable additive for modified asphalt, 2. the suitability of PCC pavements in urban settings should be reexamined, 3. Surface modification of GTR materials can improve compatibilization of particles for the manufacture of asphalt materials, and 4. gasoline sales are generally price inelastic in both the U.S. and California. Ultimately, these four studies improve understanding of road pavement materials and transport energy demand. They lay out important information about the future of the relationship between materials and design in the transportation industry. These findings may be used by engineers, policymakers, and others in the industry to better consider implications of decisions involved in design, creation, and modification of structures using pavement and concrete, including roads, bridges, etc

On-Surface Synthesis and Characterization of Triply Fused Porphyrin–Graphene Nanoribbon Hybrids

This is the peer reviewed version of the following article: Angewandte Chemie - International Edition 59. 3 (2020): 1334-1339, which has been published in final form at https://doi.org/10.1002/anie.201913024. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsOn-surface synthesis offers a versatile approach to prepare novel carbon-based nanostructures that cannot be obtained by conventional solution chemistry. Graphene nanoribbons (GNRs) have potential for a variety of applications. A key issue for their application in molecular electronics is in the fine-tuning of their electronic properties through structural modifications, such as heteroatom doping or the incorporation of non-benzenoid rings. In this context, the covalent fusion of GNRs and porphyrins (Pors) is a highly appealing strategy. Herein we present the selective on-surface synthesis of a Por–GNR hybrid, which consists of two Pors connected by a short GNR segment. The atomically precise structure of the Por–GNR hybrid has been characterized by bond-resolved scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc-AFM). The electronic properties have been investigated by scanning tunneling spectroscopy (STS), in combination with DFT calculations, which reveals a low electronic gap of 0.4 eVFinancial support from Spanish MICINN (CTQ2017‐85393‐P) is acknowledged. IMDEA Nanociencia acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, Grant SEV2016‐0686). This work was supported by the Swiss National Science Foundation (200020_182015, IZLCZ2_170184) and the NCCR MARVEL funded by the Swiss National Science Foundation (51NF40‐182892). Computational support from the Swiss Supercomputing Center (CSCS) under project ID s904 is gratefully acknowledged. Q.S. acknowledges the EMPAPOSTDOCS‐II programme under the Marie Sklodowska‐Curie grant agreement No 75436

On-surface Synthesis and Characterization of Triply-fused Porphyrin-Graphene Nanoribbon Hybrids

On‐surface synthesis offers a versatile approach to fabricate novel carbon‐based nanostructures that cannot be obtained via conventional solution chemistry. Within the family of such nanomaterials, graphene nanoribbons (GNRs) hold a privileged position due to their high potential for a variety of applications. One of the key issues for their application in molecular electronics lies in the fine‐tuning of their electronic properties through structural modifications, such as heteroatom doping or the incorporation of non‐benzenoid rings. In this context, the covalent fusion of GNRs and porphyrins (Pors) represents a highly appealing strategy. In this work, we present the selective on‐surface synthesis of a Por‐GNR hybrid, which consists of two Pors connected by a short GNR segment. The atomically precise structure of the obtained dimer has been unambiguously characterized by bond‐resolved scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc‐AFM). The electronic properties of the dimer have been investigated by STS in combination with DFT calculations, which reveals a low electronic gap of 0.4 eV

Green Catalysts: Applied and Synthetic Photosynthesis

The biological process of photosynthesis was critical in catalyzing the oxygenation of Earth’s atmosphere 2.5 billion years ago, changing the course of development of life on Earth. Recently, the fields of applied and synthetic photosynthesis have utilized the light-driven protein–pigment supercomplexes central to photosynthesis for the photocatalytic production of fuel and other various valuable products. The reaction center Photosystem I is of particular interest in applied photosynthesis due to its high stability post-purification, non-geopolitical limitation, and its ability to generate the greatest reducing power found in nature. These remarkable properties have been harnessed for the photocatalytic production of a number of valuable products in the applied photosynthesis research field. These primarily include photocurrents and molecular hydrogen as fuels. The use of artificial reaction centers to generate substrates and reducing equivalents to drive non-photoactive enzymes for valuable product generation has been a long-standing area of interest in the synthetic photosynthesis research field. In this review, we cover advances in these areas and further speculate synthetic and applied photosynthesis as photocatalysts for the generation of valuable products

Excited state interactions between the chiral Au 38 L 24 cluster and covalently attached porphyrin

A protected S-acetylthio porphyrin was synthesized and attached to the Au38(2-phenylethanethiolate)24 cluster in a ligand exchange reaction. Chiral high performance liquid chromatography of the functionalized cluster yielded enantiomeric pairs of clusters probably differing in the binding site of the porphyrin. As proven by circular dichroism, the chirality was maintained. Exciton coupling between the cluster and the chromophore is observed. Zinc can be incorporated into the porphyrin attached to the cluster, as evidenced by absorption and fluorescence spectroscopy, however, the reaction is slow. Quenching of the chromophore fluorescence is observed, which can be explained by energy transfer from the porphyrin to the cluster. Transient absorption spectra of Au38(2-phenylethanethiolate)24 and the functionalized cluster probe the bleach of the gold cluster due to ground state absorption and the characteristic excited state absorption signals. Zinc incorporation does not have a pronounced effect on the photophysical behaviour. Decay times are typical for the molecular behaviour of small monolayer protected gold clusters

Synthesis and characterization of silicon phthalocyanines bearing axial phenoxyl groups for attachment to semiconducting metal oxides

A series of axial phenoxy substituted octabutoxy silicon phthalocyanines bearing ethyl carboxylic ester and diethyl phosphonate groups have been prepared from the corresponding phenols in pyridine. Axial bis-hydroxy silicon phthalocyanine was prepared using an adaptation of a reported protocol [1, 2] from the octabutoxy free-base phthalocyanine. The phenols bear either carboxylic ester or phosphonate groups, which upon deprotection can serve as anchoring groups for attaching the phthalocyanines to semiconducting metal oxides used in dye sensitized solar cells (DSSCs). All the phthalocyanines of the series absorb in the near infra-red region: 758-776 nm. The first oxidation potential for each phenoxy derivative occurs near 0.55 V vs. SCE as measured by cyclic voltammetry, with all falling within a 10 mV range. This indicates that these dyes will have sufficient energy in the photo-excited state to drive the reduction of protons to hydrogen. Taking into account the absorption and electrochemical potentials, these dyes are promising candidates for use in dual-threshold photo-electrochemical cells. © 2011 World Scientific Publishing Company.Fil: Bergkamp, Jesse J.. Center For Bio-inspired Solar Fuel Production; Estados Unidos. Arizona State University; Estados UnidosFil: Sherman, Benjamin D.. Center For Bio-inspired Solar Fuel Production; Estados Unidos. Arizona State University; Estados UnidosFil: Mariño Ochoa, Ernesto. Instituto Tecnológico de Monterrey; MéxicoFil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados; ArgentinaFil: Cosa, Gonzlao. McGill University. Department of Chemistry; CanadáFil: Moore, Thomas A.. Center For Bio-inspired Solar Fuel Production; Estados Unidos. Arizona State University; Estados UnidosFil: Gust, Devens. Center For Bio-inspired Solar Fuel Production; Estados Unidos. Arizona State University; Estados UnidosFil: Moore, Ana L.. Center For Bio-inspired Solar Fuel Production; Estados Unidos. Arizona State University; Estados Unido

Photoinduced Electron Transfer in Perylene-TiO2 Nanoassemblies

The photosensitization effect of three perylene dye derivatives on titanium dioxide nanoparticles (TiO2 NPs) has been investigated. The dyes used, 1,7-dibromoperylene-3,4,9,10-tetracarboxy dianhydride (1), 1,7-dipyrrolidinylperylene-3,4,9,10-tetracarboxy dianhydride (2) and 1,7-bis(4-tert-butylphenyloxy)perylene-3,4,9,10-tetracarboxy dianhydride (3) have in common bisanhydride groups that convert into TiO2 binding groups upon hydrolysis. The different substituents on the bay position of the dyes enable tuning of their redox properties to yield significantly different driving forces for photoinduced electron transfer (PeT). Recently developed TiO2 NPs having a small average size and a narrow distribution (4 ± 1 nm) are used in this work to prepare the dye-TiO2 systems under study. Whereas successful sensitization was obtained with 1 and 2 as evidenced by steady-state spectral shifts and transient absorption results, no evidence for the attachment of 3 to TiO2 was observed. The comparison of the rates of PeT (kPeT) for 1- and 2-TiO2 systems studied in this work with those obtained for previously reported analogous systems, having TiO2 NPs covered by a surfactant layer (Hernandez et al. [2012] J. Phys. Chem. B., 117, 4568–4581), indicates that kPeT for the former systems is slower than that for the later. These results are interpreted in terms of the different energy values of the conduction band edge in each system.Fil: Llansola Portolés, Manuel Jose. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bergkamp, Jesse J.. Arizona State University; Estados UnidosFil: Tomlin, John. Arizona State University; Estados UnidosFil: Moore, Thomas A.. Arizona State University; Estados UnidosFil: Kodis, Gerdenis. Arizona State University; Estados UnidosFil: Moore, Ana L.. Arizona State University; Estados UnidosFil: Cosa, Gonzalo. McGill University; CanadáFil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin