A Comparative Study of Methods of Proportioning Concrete

A continual increase in the use of concrete as a building material has greatly increased the demand for more definite knowledge of the factors that are conductive to strength and economy of construction. It has been found necessary to acquire this knowledge largely through definite and extensive experimental work under conditions that can be carefully controlled and regulated. Although a considerable amount of experimental work upon the properties and proportioning of concrete has been performed in the last decade, the conflicting statements that have been made clearly indicate that this field of research and investigation is by no means complete. This condition is particularly true of the present methods of proportioning and placing concrete in the large structures that are now being built of reinforced-concrete instead of wood or steel. Many results have been obtained, however, that are worthy of more investigation and that deserve more careful study. It is these general and sometimes indefinite conclusions that have been taken as a basis for further study. The investigation has been conducted in two main parts: A. Study of Aggregates. 1. Volume of Combined Aggregate 2. Use of Colorimetric Test 3. Sieve Analysis and Calculation of Surface Area 4. Determination of the amount of voids and variation in the amount of sand in bank run gravel. 5. Fineness Modulus B. Methods of Proportioning 1. Void Measurement 2. Maximum Density or Ideal Curve 3. Surface Area 4. Fineness Modulus 5. Iowa State Highway Commission C. Discussion of the Various Methods D. Conclusio

Model Study of an Offshore Drilling Structure

Technical Report No. 6Bethlehem Steel Company, Shipbuilding Divisionhttp://deepblue.lib.umich.edu/bitstream/2027.42/133669/1/39015095796374.pd

Real-time performance monitoring of tuned mass damper system for a 183 m reinforced concrete chimney

A 183 m reinforced concrete chimney for a coal-fired power station was instrumented in the latter part of its life during the construction of a replacement chimney. Because of concerns about large-amplitude response induced by interference effects from the new chimney in the prevailing upwind direction, a response monitoring system was installed, quickly followed by a tuned mass damper (TMD) system. As well as providing live display of the chimney response, the monitoring system was also used to check the functioning of the TMD. The monitoring system featured a direct implementation of the stochastic subspace identification procedure in the 'virtual instrument' controlling the system, so that modal damping values for the system were displayed automatically, in real-time. The system thus provided an immediate visual indication of increased damping levels during strong winds, showing the correct functioning of the TMD. The paper describes the chimney, the monitoring system and its installation, the data processing and system identification procedure, together with performance data before, during and after installation of the TMD. (C) 2009 Elsevier Ltd. All rights reserved

Post-Transcriptional Regulation of Interleukin-6 Gene Expression in Human Keratinocytes by Ultraviolet B Radiation

Exposure to increasing doses (290-315 nm) of ultraviolet (UV) B radiation is thought to profoundly affect human health. Studies on the biologic and molecular effects of UVB radiation on human skin are therefore of particular interest. There is experimental and clinical evidence to assume that UVB radiation-induced local and systemic inflammatory reactions might be mediated at least in part by UVB-induced keratinocyte-derived interleukin (IL)-6. Previously, a UVB-induced increase of steady-state levels of IL-6 mRNA was found to be a prerequisite for keratinocyte IL-6 production after UVB irradiation. The present study was aimed at addressing the question of whether in vitro UVB irradiation would increase IL-6 mRNA expression in long-term cultured, normal human keratinocytes via transcriptional or post-transcriptional mechanisms. UVB exposure (0-100 J/m2) of keratinocytes increased low baseline expression levels of lL-6 mRNA in a time- and dose-dependent manner. Using nuclear run-on assays, transcription rates of the II,-6 gene in nuclei isolated from UVB-irradiated cells were found to be essentially identical to those seen in unirradiated cells, indicating that UVB light did not lead to increased transcription of the IL-6 gene. To determine a possible post-transcriptional mechanism in UVB-induced IL-6 mRNA expression, the effects of UVB irradiation on IL-6 mRNA stability were examined. To this end irradiated and unirradiated keratinocytes were treated with actinomycin D and subjected to Northern blot analysis to calculate IL-6 mRNA half-life. As compared with unirradiated cells, IL-6 mRNA stability was increased significantly (three- to four-fold) in UVB-irradiated cells, suggesting that UVB radiation upregulates IL-6 mRNA levels in human keratinocytes by increasing the stability of IL-6 transcripts. This is the first report indicating that UVB radiation at a physiologically relevant dose may affect gene expression in human cells at a post-transcriptional level

Evaluation of Microorganisms Cultured from Injured and Repressed Tissue Regeneration Sites in Endangered Giant Aquatic Ozark Hellbender Salamanders

Investigation into the causes underlying the rapid, global amphibian decline provides critical insight into the effects of changing ecosystems. Hypothesized and confirmed links between amphibian declines, disease, and environmental changes are increasingly represented in published literature. However, there are few long-term amphibian studies that include data on population size, abnormality/injury rates, disease, and habitat variables to adequately assess changes through time. We cultured and identified microorganisms isolated from abnormal/injured and repressed tissue regeneration sites of the endangered Ozark Hellbender, Cryptobranchus alleganiensis bishopi, to discover potential causative agents responsible for their significant decline in health and population. This organism and our study site were chosen because the population and habitat of C. a. bishopi have been intensively studied from 1969–2009, and the abnormality/injury rate and apparent lack of regeneration were established. Although many bacterial and fungal isolates recovered were common environmental organisms, several opportunistic pathogens were identified in association with only the injured tissues of C.a. bishopi. Bacterial isolates included Aeromonas hydrophila, a known amphibian pathogen, Granulicetella adiacens, Gordonai terrae, Stenotrophomonas maltophilia, Aerococcus viridans, Streptococcus pneumoniae and a variety of Pseudomonads, including Pseudomonas aeruginosa, P. stutzeri, and P. alcaligenes. Fungal isolates included species in the genera Penicillium, Acremonium, Cladosporium, Curvularia, Fusarium, Streptomycetes, and the Class Hyphomycetes. Many of the opportunistic pathogens identified are known to form biofilms. Lack of isolation of the same organism from all wounds suggests that the etiological agent responsible for the damage to C. a. bishopi may not be a single organism. To our knowledge, this is the first study to profile the external microbial consortia cultured from a Cryptobranchid salamander. The incidence of abnormalities/injury and retarded regeneration in C. a. bishopi may have many contributing factors including disease and habitat degradation. Results from this study may provide insight into other amphibian population declines

Rapid toxicity testing based on mitochondrial respiratory activity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47992/1/128_2005_Article_BF01701787.pd