The Influence of Bicycle Oriented Facilities on Bicycle Crashes within Crash Concentrated Areas

<div><p><b>Objective:</b> This study analyzes environmental features that influence bicycle crashes within crash concentrated areas. This study particularly provides a systemic approach to analyzing major bicycle oriented facilities contributing to bicycle crashes within crash concentrated areas.</p><p><b>Methods:</b> This study applies geographic information systems (GIS) to the identification of crash concentrated areas in Riverside County, California using five years of crash data as well as the development of environment feature data inventory. Based on the data inventory, a regression method was applied to discover whether there was a correlation between the presence of bicycle facilities and the occurrence of bicycle crashes.</p><p><b>Results:</b> This study identifies that longer distance between crosswalks and bus stops are positively associated with bicyclist crashes, while structured medians contribute to the reduction of bicycle crashes. This study also suggests that parking lot entrance ways and parking lots with no physical barrier from sidewalks cause bicycle crashes on sidewalks.</p><p><b>Conclusions:</b> This study presents guidelines for local transportation planners to analyze the patterns of bicyclist crashes in order to improve roadway safety. This research also assists planners in effectively allocating scarce resources as they address issues of bicyclist safety.</p></div

Room-Temperature Dynamics of Vanishing Copper Nanoparticles Supported on Silica

In heterogeneous catalysis, a nanoparticle (NP) system has immediate chemical surroundings with which its interaction needs to be considered, as nanoparticles are typically loaded onto certain supports. Beyond what is known about these interactions, dynamic atomic interactions between the nanoparticle and support could result from the increased energetics at the nanoscale. Here, we show that the dynamic response of atoms in copper nanoparticles to the underlying silica support at room temperature and ambient atmosphere results in the complete disappearance of supported nanoparticles over the course of only a few weeks. A quantitative study of copper nanoparticles at various size regimes (6–17 nm) revealed the significance of size-dependent nanoparticle energetics to the interaction with the support. Extended X-ray absorption fine structure is used to show that copper atoms could readily diffuse into the support to be locally surrounded by oxygen and silicon with structurally disordered outer coordination shells. Increased energetic states at the nanoscale and the energetically favorable configuration of individual copper atoms within silica, identified through EXAFS, are suggested as the cause of nanoparticle disappearance. This unexpected observation opens up new questions as to how nanoparticles interact with surrounding environments that could fundamentally change our conventional view of supported nanoparticle systems

Additional file 2: Table S1. of Extracorporeal membrane oxygenation for life-threatening asthma refractory to mechanical ventilation: analysis of the Extracorporeal Life Support Organization registry

Complications. Table S2. Reason for extracorporeal membrane oxygenation discontinuation and mortality. (DOC 80 kb

Age and income-adjusted odds ratio for abortion and obstetric complications by industry (vs. non-working women).

<p>Age and income-adjusted odds ratio for abortion and obstetric complications by industry (vs. non-working women).</p

Structure-Sensitive CO₂ Electroreduction to Hydrocarbons on Ultrathin 5‑fold Twinned Copper Nanowires

Copper is uniquely active for the electrocatalytic reduction of carbon dioxide (CO₂) to products beyond carbon monoxide, such as methane (CH₄) and ethylene (C₂H₄). Therefore, understanding selectivity trends for CO₂ electrocatalysis on copper surfaces is critical for developing more efficient catalysts for CO₂ conversion to higher order products. Herein, we investigate the electrocatalytic activity of ultrathin (diameter ∼20 nm) 5-fold twinned copper nanowires (Cu NWs) for CO₂ reduction. These Cu NW catalysts were found to exhibit high CH₄ selectivity over other carbon products, reaching 55% Faradaic efficiency (FE) at −1.25 V versus reversible hydrogen electrode while other products were produced with less than 5% FE. This selectivity was found to be sensitive to morphological changes in the nanowire catalyst observed over the course of electrolysis. Wrapping the wires with graphene oxide was found to be a successful strategy for preserving both the morphology and reaction selectivity of the Cu NWs. These results suggest that product selectivity on Cu NWs is highly dependent on morphological features and that hydrocarbon selectivity can be manipulated by structural evolution or the prevention thereof

Directed Assembly of Nanoparticle Catalysts on Nanowire Photoelectrodes for Photoelectrochemical CO₂ Reduction

Reducing carbon dioxide with a multicomponent artificial photosynthetic system, closely mimicking nature, represents a promising approach for energy storage. Previous works have focused on exploiting light-harvesting semiconductor nanowires (NW) for photoelectrochemical water splitting. With the newly developed CO₂ reduction nanoparticle (NP) catalysts, direct interfacing of these nanocatalysts with NW light absorbers for photoelectrochemical reduction of CO₂ becomes feasible. Here, we demonstrate a directed assembly of NP catalysts on vertical NW substrates for CO₂-to-CO conversion under illumination. Guided by the one-dimensional geometry, well-dispersed assembly of Au₃Cu NPs on the surface of Si NW arrays was achieved with facile coverage tunability. Such Au₃Cu NP decorated Si NW arrays can readily serve as effective CO₂ reduction photoelectrodes, exhibiting high CO₂-to-CO selectivity close to 80% at −0.20 V vs RHE with suppressed hydrogen evolution. A reduction of 120 mV overpotential compared to the planar (PL) counterpart was observed resulting from the optimized spatial arrangement of NP catalysts on the high surface area NW arrays. In addition, this system showed consistent photoelectrochemical CO₂ reduction capability up to 18 h. This simple photoelectrode assembly process will lead to further progress in artificial photosynthesis, by allowing the combination of developments in each subfield to create an efficient light-driven system generating carbon-based fuels

Tunable Cu Enrichment Enables Designer Syngas Electrosynthesis from CO₂

Using renewable energy to recycle CO₂ provides an opportunity to both reduce net CO₂ emissions and synthesize fuels and chemical feedstocks. It is of central importance to design electrocatalysts that both are efficient and can access a tunable spectrum of products. Syngas, a mixture of carbon monoxide (CO) and hydrogen (H₂), is an important chemical precursor that can be converted downstream into small molecules or larger hydrocarbons by fermentation or thermochemistry. Many processes that utilize syngas require different syngas compositions: we therefore pursued the rational design of a family of electrocatalysts that can be programmed to synthesize different designer syngas ratios. We utilize <i>in situ</i> surface-enhanced Raman spectroscopy and first-principles density functional theory calculations to develop a systematic picture of CO* binding on Cu-enriched Au surface model systems. Insights from these model systems are then translated to nanostructured electrocatalysts, whereby controlled Cu enrichment enables tunable syngas production while maintaining current densities greater than 20 mA/cm²

Comparison of Hygroscopicity, Volatility, and Mixing State of Submicrometer Particles between Cruises over the Arctic Ocean and the Pacific Ocean

Ship-borne measurements of ambient aerosols were conducted during an 11 937 km cruise over the Arctic Ocean (cruise 1) and the Pacific Ocean (cruise 2). A frequent nucleation event was observed during cruise 1 under marine influence, and the abundant organic matter resulting from the strong biological activity in the ocean could contribute to the formation of new particles and their growth to a detectable size. Concentrations of particle mass and black carbon increased with increasing continental influence from polluted areas. During cruise 1, multiple peaks of hygroscopic growth factor (HGF) of 1.1–1.2, 1.4, and 1.6 were found, and higher amounts of volatile organic species existed in the particles compared to that during cruise 2, which is consistent with the greater availability of volatile organic species caused by the strong oceanic biological activity (cruise 1). Internal mixtures of volatile and nonhygroscopic organic species, nonvolatile and less-hygroscopic organic species, and nonvolatile and hygroscopic nss-sulfate with varying fractions can be assumed to constitute the submicrometer particles. On the basis of elemental composition and morphology, the submicrometer particles were classified into C-rich mixture, S-rich mixture, C/S-rich mixture, Na-rich mixture, C/P-rich mixture, and mineral-rich mixture. Consistently, the fraction of biological particles (i.e., P-containing particles) increased when the ship traveled along a strongly biologically active area

Electrochemical Activation of CO₂ through Atomic Ordering Transformations of AuCu Nanoparticles

Precise control of elemental configurations within multimetallic nanoparticles (NPs) could enable access to functional nanomaterials with significant performance benefits. This can be achieved down to the atomic level by the disorder-to-order transformation of individual NPs. Here, by systematically controlling the ordering degree, we show that the atomic ordering transformation, applied to AuCu NPs, activates them to perform as selective electrocatalysts for CO₂ reduction. In contrast to the disordered alloy NP, which is catalytically active for hydrogen evolution, ordered AuCu NPs selectively converted CO₂ to CO at faradaic efficiency reaching 80%. CO formation could be achieved with a reduction in overpotential of ∼200 mV, and catalytic turnover was enhanced by 3.2-fold. In comparison to those obtained with a pure gold catalyst, mass activities could be improved as well. Atomic-level structural investigations revealed three atomic gold layers over the intermetallic core to be sufficient for enhanced catalytic behavior, which is further supported by DFT analysis

Metal–Organic Frameworks for Electrocatalytic Reduction of Carbon Dioxide

A key challenge in the field of electrochemical carbon dioxide reduction is the design of catalytic materials featuring high product selectivity, stability, and a composition of earth-abundant elements. In this work, we introduce thin films of nanosized metal–organic frameworks (MOFs) as atomically defined and nanoscopic materials that function as catalysts for the efficient and selective reduction of carbon dioxide to carbon monoxide in aqueous electrolytes. Detailed examination of a cobalt–porphyrin MOF, Al₂(OH)₂TCPP-Co (TCPP-H₂ = 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayl)­tetrabenzoate) revealed a selectivity for CO production in excess of 76% and stability over 7 h with a per-site turnover number (TON) of 1400. In situ spectroelectrochemical measurements provided insights into the cobalt oxidation state during the course of reaction and showed that the majority of catalytic centers in this MOF are redox-accessible where Co­(II) is reduced to Co­(I) during catalysis