The stress and displacement fields at the tip of crazes in glassy polymers

This analysis models a craze region in glassy polymers as an elastic transversely isotropic homogeneous inclusion of thin elliptical shape with different elastic properties from the bulk polymer. The plane elasticity problem for an applied uniform stress field is solved and the results dimensionalized with respect to the craze tip radius. Stress and strain enhancements of several times far field values are found to occur at the craze tip and are independent of craze tip radius. These results are consistent with experimentally observed characteristics of craze growth and should be important in assessing the relative merits of different criteria that have been proposed for craze growth in glassy polymers.     

Mobil Zeolite Catalysts for Monomers

It has been about 20 years since Plank, Rosinski, and Hawthorne reported their spectacular results with metal-modified zeolite cracking catalysts for more efficient production of gasoline [1]. This discovery has saved an estimated 200 million barrels of crude oil each year in the United States alone [2]. In 1972, a patent by Argauer and Landolt described the preparation of a member of a generation of new synthetic zeolites, called ZSM- 5. It was unique because of its high silica/alumina ratio and greatly reduced coking rates for reactions with hydrocarbons by comparison with known low silica zeolites [3]. This material was an early member of a series of over 50 synthetic zeolitic substances prepared in Mobil laboratories.     

Forest bioenergy or forest carbon? Assessing trade-offs in greenhouse gas mitigation with wood-based fuels

The potential of forest-based bioenergy to reduce greenhouse gas (GHG) emissions when displacing fossil-based energy must be balanced with forest carbon implications related to biomass harvest. We integrate life cycle assessment (LCA) and forest carbon analysis to assess total GHG emissions of forest bioenergy over time. Application of the method to case studies of wood pellet and ethanol production from forest biomass reveals a substantial reduction in forest carbon due to bioenergy production. For all cases, harvest-related forest carbon reductions and associated GHG emissions initially exceed avoided fossil fuel-related emissions, temporarily increasing overall emissions. In the long term, electricity generation from pellets reduces overall emissions relative to coal, although forest carbon losses delay net GHG mitigation by 16-38 years, depending on biomass source (harvest residues/standing trees). Ethanol produced from standing trees increases overall emissions throughout 100 years of continuous production: ethanol from residues achieves reductions after a 74 year delay. Forest carbon more significantly affects bioenergy emissions when biomass is sourced from standing trees compared to residues and when less GHG-intensive fuels are displaced. In all cases, forest carbon dynamics are significant. Although study results are not generalizable to all forests, we suggest the integrated LCA/forest carbon approach be undertaken for bioenergy studies.     

Issues in the Reconstruction of Gene Order Evolution

As genomes evolve over hundreds of millions years, the chromosomes become rearranged, with segments of some chromosomes inverted, while other chromosomes reciprocally exchange chunks from their ends. These rearrangements lead to the scrambling of the elements of one genome with respect to another descended from a common ancestor. Multidisciplinary work undertakes to mathematically model these processes and to develop statistical analyses and mathematical algorithms to understand the scrambling in the chromo...     

GLUCOSE OXIDASE REACTION FOR ESTIMATION OF GLUCOSE WITHOUT HORSERADISH PEROXIDASE. SOME MICROBIOLOGICAL AND FERMENTATION APPLICATIONS

An enzymic method has been developed for analysis of glucose. Glucose oxidase acts on glucose to produce hydrogen peroxide which acts to directly reduce the green Cu(II) 2–2′-bicinchoninate complex to a violet complex without horseradish peroxidase. A concentration range of 20–200 μM glucose was used but the reaction shows a linear range of 20–800 μM glucose. Interference is controlled by using a blank determination which has not been treated with glucose oxidase. The reaction has been used to estimate glucose levels in Saccharomyces cerevisiae fermentation and α-amylase, invertase and β-galactosidase reactions and coloured corn-steep fermentation media.     

Fermentation characteristics,aerobic stability and ruminal degradation of ensiled pea/wheat bi‐crop forages treated with two microbial inoculants,formic acid or quebracho tannins

This study evaluated the effects of two commonly used microbial inoculants (Lactobacillus buchneri (LB) and Lactobacillus plantarum (LP)), formic acid (FA) and quebracho tannins (QT) on the fermentation quality, aerobic stability and in situ rumen degradation of pea/wheat bi‐crop forages. Precision‐chopped spring pea (Pisum sativum, var Magnus) and wheat (Triticum aestivum, var Axona) bi‐crops (3:1 pea/wheat ratio) harvested at a combined dry matter (DM) content of 301 g kg^?1 were used for the study. The bi‐crops were conserved without (Control) or with inoculants based on lactic acid bacteria (LB (10⁵ CFU g^?1 fresh weight (FW)) or LP (10⁶ CFU g^?1 FW)), QT (16 g kg^?1 FW) or FA (2.5 g kg^?1 FW) in laboratory silos of 1.5 kg capacity, with each treatment being replicated six times. The pH, chemical composition, aerobic stability and in situ rumen degradation of DM, nitrogen (N) and neutral detergent fibre (NDF) after 112 days of ensilage were measured. The average pH at silo opening was 4.0, suggesting that the silages were well fermented. There were no significant effects of additive treatment on water‐soluble carbohydrate, total N, soluble N, ammonia N and NDF. Lactic acid and acetic acid were the main fermentation products. High concentrations of acetic acid were found in all the treatments, indicating a heterofermentative pathway. Although FA treatment gave the most aerobically stable silage, the Control and QT‐treated silages did not heat up by more than 1 °C until after 6 days of exposure to air. There were no effects of additives on DM degradation characteristics. However, the inoculants increased the rate of N and NDF degradation in the rumen, and both FA and QT reduced the effective and potential degradation of N. © 2001 Society of Chemical Industry     

Developing English domestic occupancy profiles

ABSTRACT

Occupancy patterns are necessary to estimate energy demand and evaluate thermal comfort in households. Because of this, many European countries are developing representative domestic schedules to replace outdated criteria. This paper evaluates the state of knowledge of UK domestic occupancy patterns and develops new domestic occupancy profiles for England. The presented research (1) characterizes methods for collecting occupancy data and inferring patterns; (2) identifies and assesses the quality of categories of occupancy patterns used in building simulation; and (3) develops updated occupancy profiles. A systematic scoping review identified social and monitoring surveys as the most deployed data-collection methods. A systematic literature review also established that the occupancy categories most frequently used in UK building simulation are (a) a family with dependent children where the parents work full time; and (b) a retired elderly couple who spend most of their time indoors. The interview sample from the English Housing Survey 2014–15 was used to map household typologies. Results show that categories (a) and (b) combined amount to only 19% of England’s households, which suggest models are over-reliant on these groups. Considering this result, the paper develops occupancy patterns for England derived from 2015 UK Time Use Survey diaries for each household typology previously identified.     

包容性工程—借助工程技术发明为身体或精神障碍人士赋能

1. Background The use of engineering tools, design, research, and thinking to create environments and capabilities whereby individuals who are currently under-e...     

Increased globotriaosylceramide in familial dysautonomia

Familial Dysautonomia (FD) is an autosomal recessive disease of unknown etiology, occurring primarily in Ashkenazi Jews. Patients are neurologically impaired, with deficits primarily in autonomic and sensory functions. The biochemical and genetic defects have remained elusive, precluding carrier detection and prenatal diagnosis. High-performance liquid chromatography data indicated up to a threefold increase in the neutral glycosphingolipid globotriaosylceramide in Dysautonomic fibroblasts and lymphoblasts. Total ganglioside values, measured by colorimetric, fluorometric or specific sodium borohydride incorporation, were decreased. Affected fibroblasts exhibited a range of pleomorphic phenotypes, such that the usual swirl-like confluent growth pattern of normal fibroblasts was distorted to varying degrees, suggesting abnormalities in the FD plasma membrane, possibly affecting cell-cell contacts. The glycosphingolipid increase could not be accounted for on the basis of markedly decreased α-galactosidase activity, as in Fabry's disease, where patients also display decreased autonomic function.