Effects of Urban Sprawl and Vehicle Miles Traveled on Traffic Fatalities

<div><p><b>Objective</b>: Previous research suggests that urban sprawl increases auto-dependency and that excessive auto use increases the risk of traffic fatalities. This indirect effect of urban sprawl on traffic fatalities is compared to non–vehicle miles traveled (VMT)-related direct effect of sprawl on fatalities.</p><p><b>Methods</b>: We conducted a path analysis to examine the causal linkages among urban sprawl, VMT, traffic fatalities, income, and fuel cost. The path diagram includes 2 major linkages: the direct relationship between urban sprawl and traffic fatalities and the indirect effect on fatalities through increased VMT in sprawling urban areas. To measure the relative strength of these causal linkages, path coefficients are estimated using data collected nationally from 147 urbanized areas in the United States.</p><p><b>Results</b>: Through both direct and indirect paths, urban sprawl is associated with greater numbers of traffic fatalities, but the direct effect of sprawl on fatalities is more influential than the indirect effect.</p><p><b>Conclusions</b>: Enhancing traffic safety can be achieved by impeding urban sprawl and encouraging compact development. On the other hand, policy tools reducing VMT may be less effective than anticipated for traffic safety.</p></div

Synthesis of ¹³C‑,¹⁵N‑Labeled Graphitic Carbon Nitrides and NMR-Based Evidence of Hydrogen-Bonding Assisted Two-Dimensional Assembly

Graphitic carbon nitride (g-C₃N₄) has gained great attention as a material of promise for artificial photosynthesis. In place of synthesis of traditional three-dimensional g-C₃N₄ via polymerization of melamine or melem, recent studies seek to establish an alternative synthetic approach for two-dimensional g-C₃N₄ using a smaller precursor such as urea. However, the effectiveness of such a synthetic approach and resultant polymeric forms of g-C₃N₄ in this approach are still largely unknown. In this study, we present that solid-state NMR (SSNMR) analysis for ¹³C- and ¹⁵N-labeled g-C₃N₄ prepared from urea offers an unparalleled structural view for the heterogeneous in-plane structure of g-C₃N₄ and most likely for its moieties. We revealed that urea was successfully assembled in melem oligomers, which include extended oligomers involving six or more melem subunits. SSNMR, transmission electron micrograph, and <i>ab initio</i> calculation data suggested that the melem oligomer units were further extended into graphene-like layered materials via widespread NH–N hydrogen bonds between oligomers

In Situ Modulation of Cell Behavior via Smart Dual-Ligand Surfaces

Due to the highly complex nature of the extracellular matrix (ECM), the design and implementation of dynamic, stimuli-responsive surfaces that present well-defined ligands and serve as model ECM substrates have been of tremendous interest to biomaterials, biosensor, and cell biology communities. Such tools provide strategies for identifying specific ligand–receptor interactions that induce vital biological consequences. Herein, we report a novel dual-ligand-presenting surface methodology that modulates dynamic ECM properties to investigate various cell behaviors. Peptides PHSRN, cRGD, and KKKTTK, which mimic the cell- and heparan sulfate-binding domains of fibronectin, and carbohydrates Gal and Man were combined with cell adhesive RGD to survey possible synergistic or antagonist ligand effects on cell adhesion, spreading, growth, and migration. Soluble molecule and enzymatic inhibition assays were also performed, and the levels of focal adhesion kinase in cells subjected to different ligand combinations were quantified. A redox-responsive trigger was incorporated into this surface strategy to spontaneously release ligands in the presence of adhered cells, and cell spreading, growth, and migration responses were measured and compared. The identity and nature of the dual-ligand combination directly influenced cell behavior

General Chemoselective and Redox-Responsive Ligation and Release Strategy

We report a switchable redox click and cleave reaction strategy for conjugating and releasing a range of molecules on demand. This chemoselective redox-responsive ligation (CRRL) and release strategy is based on a redox switchable oxime linkage that is controlled by mild chemical or electrochemical redox signals and can be performed at physiological conditions without the use of a catalyst. Both conjugation and release reactions are kinetically well behaved and quantitative. The CRRL strategy is synthetically modular and easily monitored and characterized by routine analytical techniques. We demonstrate how the CRRL strategy can be used for the dynamic generation of cyclic peptides and the ligation of two different peptides that are stable but can be selectively cleaved upon changes in the redox environment. We also demonstrate a new redox based delivery of cargoes to live cells strategy via the CRRL methodology by synthesizing a FRET redox-responsive probe that is selectively activated within a cellular environment. We believe the ease of the CRRL strategy should find wide use in a range of applications in biology, tissue engineering, nanoscience, synthetic chemistry, and material science and will expand the suite of current conjugation and release strategies

Defect-Engineered Three-Dimensional Graphene–Nanotube–Palladium Nanostructures with Ultrahigh Capacitance

The development of three-dimensional carbon-based nanostructures is the next step forward for boosting industrial applications of carbon nanomaterials such as graphenes and carbon nanotubes. Some defects, which have been considered as detrimental factors for maintaining exceptional materials properties of two-dimensional graphene, can be actively used to synthesize three-dimensional graphene-based carbon nanostructures. Here we describe a fast and heretofore unreported defect-engineered method to synthesize three-dimensional carbon nanohybrid structures with strong bonding between graphene nanoplatelets and carbon nanotubes using simple microwave irradiation and an ionic liquid. Our one-pot method utilizes defect-engineered sequential processes: microwave-based defect generation on graphene nanoplatelets, anchoring of palladium nanoparticles on these defects, and subsequent growth of carbon nanotubes by use of an ionic liquid. The unique three-dimensional nanostructures showed an ultrahigh redox capacitance due to high porosity, a high surface-to-volume ratio from the spacer role of vertically standing one-dimensional carbon nanotubes on graphene sheets, and capacitance-like redox response of the palladium nanoparticles. The proposed defect-engineered method could lead to novel routes to synthesizing three-dimensional graphene-based nanostructures with exceptionally high performance in energy storage systems

Probing Cell-Surface Carbohydrate Binding Proteins with Dual-Modal Glycan-Conjugated Nanoparticles

Dual-modal fluorescent magnetic glyconanoparticles have been prepared and shown to be powerful in probing lectins displayed on pathogenic and mammalian cell surfaces. Blood group H1- and Le^b-conjugated nanoparticles were found to bind to BabA displaying <i>Helicobacter pylori</i>, and Le^a- and Le^b-modified nanoparticles are both recognized by and internalized into DC-SIGN and SIGN-R1 expressing mammalian cells via lectin-mediated endocytosis. In addition, glyconanoparticles block adhesion of <i>H. pylori</i> to mammalian cells, suggesting that they can serve as inhibitors of infection of host cells by this pathogen. It has been also shown that owing to their magnetic properties, glyconanoparticles are useful tools to enrich lectin expressing cells. The combined results indicate that dual-modal glyconanoparticles are biocompatible and that they can be employed in lectin-associated biological studies and biomedical applications

Defect-Engineered Three-Dimensional Graphene–Nanotube–Palladium Nanostructures with Ultrahigh Capacitance

The development of three-dimensional carbon-based nanostructures is the next step forward for boosting industrial applications of carbon nanomaterials such as graphenes and carbon nanotubes. Some defects, which have been considered as detrimental factors for maintaining exceptional materials properties of two-dimensional graphene, can be actively used to synthesize three-dimensional graphene-based carbon nanostructures. Here we describe a fast and heretofore unreported defect-engineered method to synthesize three-dimensional carbon nanohybrid structures with strong bonding between graphene nanoplatelets and carbon nanotubes using simple microwave irradiation and an ionic liquid. Our one-pot method utilizes defect-engineered sequential processes: microwave-based defect generation on graphene nanoplatelets, anchoring of palladium nanoparticles on these defects, and subsequent growth of carbon nanotubes by use of an ionic liquid. The unique three-dimensional nanostructures showed an ultrahigh redox capacitance due to high porosity, a high surface-to-volume ratio from the spacer role of vertically standing one-dimensional carbon nanotubes on graphene sheets, and capacitance-like redox response of the palladium nanoparticles. The proposed defect-engineered method could lead to novel routes to synthesizing three-dimensional graphene-based nanostructures with exceptionally high performance in energy storage systems

Additional file 1: Figure S1. of GDE2 is essential for neuronal survival in the postnatal mammalian spinal cord

Sensory neurons exhibit neurodegenerative pathology without impaired nerve conduction in the absence of Gde2. This figure illustrates the presence of neuropathology in the primary sensory neurons of the Gde2 KO, including vacuolization, lipid accrual, and cytoskeletal accumulation; and the maintenance of peripheral sensory nerve conduction. Figure S2-related to Fig. 9. Conditional ablation of Gde2 in the postnatal spinal cord prevents the developmental loss of motor neurons. This figure confirms the effective conditional ablation of Gde2 following neurogenesis. In the constitutive KO, GDE2’s absence during embryonic neurogenesis causes a reduction of alpha motor neurons in the lateral motor column; however, in the Gde2lox/-; ROSA:CreER animals, this loss is avoided by injecting 4-OHT at E17.5. Further, competitive PCR analysis shows a near complete deletion of the conditional Gde2 allele following 4-OHT delivery. Figure S3. Gde2 deletion does not perturb neuromuscular junction morphology. This figure uses wholemount immunohistochemistry to assess the integrity of the neuromuscular junction (NMJ) in aged Gde2 KO hindlimb muscle. At 19 months, no discernible pathology is present in the Gde2 KO NMJ. (DOCX 6586 kb

NMR-Based Structural Modeling of Graphite Oxide Using Multidimensional ¹³C Solid-State NMR and ab Initio Chemical Shift Calculations

Chemically modified graphenes and other graphite-based materials have attracted growing interest for their unique potential as lightweight electronic and structural nanomaterials. It is an important challenge to construct structural models of noncrystalline graphite-based materials on the basis of NMR or other spectroscopic data. To address this challenge, a solid-state NMR (SSNMR)-based structural modeling approach is presented on graphite oxide (GO), which is a prominent precursor and interesting benchmark system of modified graphene. An experimental 2D ¹³C double-quantum/single-quantum correlation SSNMR spectrum of ¹³C-labeled GO was compared with spectra simulated for different structural models using ab initio geometry optimization and chemical shift calculations. The results show that the spectral features of the GO sample are best reproduced by a geometry-optimized structural model that is based on the Lerf−Klinowski model (Lerf, A. et al. <i>Phys. Chem. B</i> <b>1998</b>, <i>102</i>, 4477); this model is composed of interconnected sp², 1,2-epoxide, and COH carbons. This study also convincingly excludes the possibility of other previously proposed models, including the highly oxidized structures involving 1,3-epoxide carbons (Szabo, I. et al. <i>Chem. Mater.</i> <b>2006</b>, <i>18</i>, 2740). ¹³C chemical shift anisotropy (CSA) patterns measured by a 2D ¹³C CSA/isotropic shift correlation SSNMR were well reproduced by the chemical shift tensor obtained by the ab initio calculation for the former model. The approach presented here is likely to be applicable to other chemically modified graphenes and graphite-based systems

Companion modelling for integrated renewable resource management: A new collaborative research approach to create common values for sustainable development

Additional file 2: Video S1. AFM (Height) of TrAA9A molecules moved and diffused across on BMCC cellulose ribbons for approximately 10 min. The images were recorded at 128 x 64 pixels, and 17-Hz scan rate. The height scale was fixed at 100 nm. The movie is played back at ~650 times of actual speed