A Study of the Methods of Interpretation of Electron-Diffraction Photographs of Gas Molecules, with Results for Benzene and Carbon Tetrachloride

The reliability and accuracy of the visual method of interpreting electron-diffraction photographs, consisting in the correlation of values of (4π sin ν/2) / λ obtained by visual measurement of rings of apparent maximum and minimum intensity with x values from a simplified theoretical curve (Eq. (7) or (8)), have been tested in the following ways: (a) The measurement and interpretation of "artificial electron-diffraction photographs" of bromine; (b) the comparison of electron-diffraction and bandspectral values of interatomic distances for bromine, chlorine and iodine chloride; (c) the study of microphotometer records for benzene, and comparison of results with those of the visual method; (d) the study of micro photometer records for carbon tetrachloride, and comparison with the visual method. It is concluded that the visual method when carefully applied leads to values of interatomic distances accurate to about 1 percent (probable error), or to ½ percent in favorable cases. The regular plane hexagon model of the benzene molecule is verified, the carbon-carbon distance in the ring being determined as 1.390±0.005A. The carbon-chlorine distance in the carbon tetrachloride molecule is determined as 1.760±0.005A. A brief discussion of the methods and results of other investigators is given

Introduction of Florida Bass Alleles into Largemouth Bass Inhabiting NortheastArkansas Stream Systems

Florida bass (Micropterus floridanus) have been introduced throughout much of the southern U.S. over the past 50 years. This species readily hybridizes with the extant largemouth bass (M. salmoides). Within Arkansas, the Florida bass is currently stocked in the southern half of the state. Previous studies of a northern Arkansas hatchery and a reservoir revealed the existence of Florida bass alleles in each. Other studies in Oklahoma and Texas have revealed the presence of Florida bass alleles in stream systems proximal to lakes stocked. Our goal was to investigate, using microsatellite analysis of 7 diagnostic loci, the presence of Florida bass alleles in 8 northeastern Arkansas streams to determine if Florida bass or hybrids had escaped from private farm ponds as compared to stocked reservoirs. We found rare instances of Florida bass alleles in most drainages, consistent with previous studies demonstrating a lack of containment of Florida bass once stocked. In Cane Creek, which flows adjacent to privately stocked farm ponds, one-third of the individuals had Florida bass alleles

Variable Phase and Electrochemical Capacitance of Electrospun MnOx Fibers

• Supercapacitors are a next-generation energy storage technology with high power and energy densities. • Nanostructured electrodes maximize surface area and theoretical capacity; manganese oxides are low-cost, low-toxicity electrode materials. • Electrospinning and thermal treatments are used to prepare nanofiber-based electrodes. • Calcination conditions affect structure and composition of the ceramic fibers. • The effects of calcination pressure and time on fiber properties are studied herein

The investigation of vertebral injury sustained during aircrew ejection. Phase 2a - Basic science experimental design and investigation of dynamic characteristics of vertebral columns considered as an engineering structure Annual report, 1 Nov. 1966 - 31 Oct. 1967

Dynamic strength studies on human vertebrae for correlation with data on effects of forcible ejection from disabled aircraf

Estimation of global final-stage energy-return-on-investment for fossil fuels with comparison to renewable energy sources

Under many scenarios, fossil fuels are projected to remain the dominant energy source until at least 2050. However, harder-to-reach fossil fuels require more energy to extract and, hence, are coming at an increasing ‘energy cost’. Associated declines in fossil fuel energy-return-on-investment ratios at first appear of little concern, given that published estimates for oil, coal and gas are typically above 25:1. However, such ratios are measured at the primary energy stage and should instead be estimated at the final stage where energy enters the economy (for example, electricity and petrol). Here, we calculate global time series (1995–2011) energy-return-on-investment ratios for fossil fuels at both primary and final energy stages. We concur with common primary-stage estimates (~30:1), but find very low ratios at the final stage: around 6:1 and declining. This implies that fossil fuel energy-return-on-investment ratios may be much closer to those of renewables than previously expected and that they could decline precipitously in the near future

Improving Ecological Restoration to Curb Biotic Invasion—A Practical Guide

Common practices for invasive species control and management include physical, chemical, and biological approaches. The first two approaches have clear limitations and may lead to unintended (negative) consequences, unless carefully planned and implemented. For example, physical removal rarely completely eradicates the targeted invasive species and can cause disturbances that facilitate new invasions by nonnative species from nearby habitats. Chemical treatments can harm native, and especially rare, species through unanticipated side effects. Biological methods may be classified as biocontrol and the ecological approach. Similar to physical and chemical methods, biocontrol also has limitations and sometimes leads to unintended consequences. Therefore, a relatively safer and more practical choice may be the ecological approach, which has two major components: (1) restoration of native species and (2) biomass manipulation of the restored community, such as selective grazing or prescribed burning (to achieve and maintain viable population sizes). Restoration requires well-planned and implemented planting designs that consider alpha-, beta-, and gamma-diversity and the abundance of native and invasive component species at local, landscape, and regional levels. Given the extensive destruction or degradation of natural habitats around the world, restoration could be most effective for enhancing ecosystem resilience and resistance to biotic invasions. At the same time, ecosystems in human-dominated landscapes, especially those newly restored, require close monitoring and careful intervention (e.g., through biomass manipulation), especially when successional trajectories are not moving as intended. Biomass management frequently uses prescribed burning, grazing, harvesting, and thinning to maintain overall ecosystem health and sustainability. Thus, the resulting optimal, balanced, and relatively stable ecological conditions could more effectively limit the spread and establishment of invasive species. Here we review the literature (especially within the last decade) on ecological approaches that involve biodiversity, biomass, and productivity, three key community/ecosystem variables that reciprocally influence one another. We focus on the common and most feasible ecological practices that can aid in resisting new invasions and/or suppressing the dominance of existing invasive species. We contend that, because of the strong influences from neighboring areas (i.e., as exotic species pools), local restoration and management efforts in the future need to consider the regional context and projected climate changes

Outsourcing or efficiency? Investigating the decline in final energy consumption in the UK productive sectors

Over the past two decades reductions in the final energy consumption of the productive sectors (industry, public administration, commercial services and agriculture), have made important contributions to overall reductions in UK final energy consumption. This study investigates the drivers of the reductions in final energy consumption in the UK productive sectors between 1997 and 2013 using a decomposition analysis that incorporates two novel approaches. Firstly, it uses results from a multi-regional input-output model to investigate how much of the structural change in the economy has been driven by outsourcing production overseas. Secondly, it utilises energy conversion chain analysis to determine how much increases in the conversion efficiency from final energy to useful exergy have contributed to improvements in final energy intensity. In aggregate all energy savings from structural change are attributed to outsourcing. Improvements in the conversion efficiency produced savings of a similar size. However energy savings from both factors have stalled since 2009. Improvements in useful exergy intensity, the useful exergy used per unit of monetary output, provided the biggest share of energy savings, but these savings are concentrated in a few sectors and rarely lead to absolute reductions in final energy use. All of this suggests that a return to the rates of energy reduction seen between 2001 and 2009 should not be taken for granted and that active policy interventions might be required to achieve further reductions

A nanoporous, ultrahydrophobic aluminum-coating process with exceptional dropwise condensation and shedding properties

Many studies have shown that dropwise condensation can enhance air-side heat transfer coefficients by at least an order of magnitude relative to filmwise condensation. However, among the hundreds of superhydrophobic surface-modification processes previously reported, there remains a lack of coating methods that enable stable dropwise condensation and can be applied to aluminum—by far the most common material for the air side of heat exchangers, e.g. in air conditioning. Here we present a bottom-up synthesis technique to grow zinc oxide-based films on to aluminum with tunable nanoporosity and strongly re-entrant surface features. These surfaces exhibit exceptional static water contact angles of up to 178° with a hysteresis less than 3° and a slide angle of 1°. We have further characterized the surfaces in the presence of six different liquids, and show that our optimal surface can repel even dipropylene glycol with a contact angle of 124°, even though its surface tension is less than half that of water. Crucially, we have also tested our films under water-condensing conditions in flowing air, characterizing the droplet-shedding behavior, and we have understood how to tune the growth process to deliver stable droplet-shedding instead of flooding. The process uses inexpensive reagents, can operate below 100 °C via immersion in an aqueous bath, and takes 1–3 h to complete, making it readily scalable to areas of many square meters and complex geometries