Three-bolt in-line connections with low ductility light-gage steel

INTRODUCTION In order to investigate the influence of ductility on the strength and behavior of bolted connections, Dhallal (1) conducted tests on single bolt lap joints using low ductility steels. As part of a separate investigation, Popowich (2) conducted tests on single, double, and triple bolt in-line lap joints using high ductility steels. The investigation reported herein was performed in order to compare the performance of 3 bolt in-line connections of high ductility steels (21 to 53% elongation in a 2 inch gage length) with that of similar 3 bolt in-line connections of low ductility steels (nominally 5 and 10% elongation in a 2 inch gage length)

Strength of bolted and welded connections in stainless steel

INTRODUCTION In 1968 the American Iron and Steel Institute published the first edition of the Specification for the Design of Light Gage Cold-Formed Stainless Steel Structural Members (1)8, , based largely on research sponsored by AISI at Cornell University. (2) That Specification covers the design of members cold-formed from six common types of austenitic stainless steel in the annealed and strain flattened condition. Additional research has been underway at Cornell on austenitic Type 301 stainless steel in the 1/4 and 1/2 hard tempers, to determine the structural behavior of these higher strength materials(3), including the behavior of structural connections. The properties of cold-rolled austenitic stainless steel are attractive for potential use in cold-formed construction. These properties include excellent corrosion resistance, exceptionally high strength, and good ductility associated with this high strength. Furthermore, all types of austenitic stainless steel, except the free machining grades, exhibit excellent weldability which greatly enhances their usefulness. This report will discuss the behavior of structural connections in Type 301 quarter and half hard stainless steel. An earlier report(3) summarizes all other phases of the Cornell investigation. A survey of industry practice in joining methods for stainless steel was conducted by AISI. The percentages of production using a particular joining method as estimated by each of the sixteen companies responding to the survey are given in Table 1. The table indicates that fusion welds are the most popular joining method, followed by resistance welds, bolted connections, and other techniques. According to the survey, fusion arc welding, resistance spot welding and bolted connections account for 90% or more of the connections currently used in stainless steel fabrication. The minimum shear strength for spot welds in 1/4 and 1/2 hard Type 301 Stainless steel has been tabulated by the American Welding Society(4). The AWS recommendations will be discussed briefly later in this report; there seems to be no need for further investigation of spot welds at this time. Therefore, the investigation described herein was limited primarily to bolted connections and to fusion welded connections using butt welds, longitudinal fillet welds and transverse fillet welds. Information on these joining methods, together with the existing AWS data, can provide the basis for design of a large majority of the structural connections in Type 301 1/4 and 1/2 hard stainless steel. * Superscripts in parentheses refer to corresponding items in References

Optical microscope and tapered fiber coupling apparatus for a dilution refrigerator

We have developed a system for tapered fiber measurements of optomechanical resonators inside a dilution refrigerator, which is compatible with both on- and off-chip devices. Our apparatus features full three-dimensional control of the taper-resonator coupling conditions enabling critical coupling, with an overall fiber transmission efficiency of up to 70%. Notably, our design incorporates an optical microscope system consisting of a coherent bundle of 37,000 optical fibers for real-time imaging of the experiment at a resolution of $\sim$1 $\mu$m. We present cryogenic optical and optomechanical measurements of resonators coupled to tapered fibers at temperatures as low as 9 mK.Comment: 7 pages, 7 figure

Optomechanics and thermometry of cryogenic silica microresonators

We present measurements of silica optomechanical resonators, known as bottle resonators, passively cooled in a cryogenic environment. These devices possess a suite of properties that make them advantageous for preparation and measurement in the mechanical ground state, including high mechanical frequency, high optical and mechanical quality factors, and optomechanical sideband resolution. Performing thermometry of the mechanical motion, we find that the optical and mechanical modes demonstrate quantitatively similar laser-induced heating, limiting the lowest average phonon occupation observed to just ~1500. Thermalization to the 9 mK thermal bath would facilitate quantum measurements on these promising nanogram-scale mechanical resonators.Comment: 10 pages, 8 figues, submission versio

Cardiomyocyte Specific Ablation of p53 Is Not Sufficient to Block Doxorubicin Induced Cardiac Fibrosis and Associated Cytoskeletal Changes

Doxorubicin (Dox) is an anthracycline used to effectively treat several forms of cancer. Unfortunately, the use of Dox is limited due to its association with cardiovascular complications which are manifested as acute and chronic cardiotoxicity. The pathophysiological mechanism of Dox induced cardiotoxicity appears to involve increased expression of the tumor suppressor protein p53 in cardiomyocytes, followed by cellular apoptosis. It is not known whether downregulation of p53 expression in cardiomyocytes would result in decreased rates of myocardial fibrosis which occurs in response to cardiomyocyte loss. Further, it is not known whether Dox can induce perivascular necrosis and associated fibrosis in the heart. In this study we measured the effects of acute Dox treatment on myocardial and perivascular apoptosis and fibrosis in a conditional knockout (CKO) mouse model system which harbours inactive p53 alleles specifically in cardiomyocytes. CKO mice treated with a single dose of Dox (20 mg/kg), did not display lower levels of myocardial apoptosis or reactive oxygen and nitrogen species (ROS/RNS) compared to control mice with intact p53 alleles. Interestingly, CKO mice also displayed higher levels of interstitial and perivascular fibrosis compared to controls 3 or 7 days after Dox treatment. Additionally, the decrease in levels of the microtubule protein α-tubulin, which occurs in response to Dox treatment, was not prevented in CKO mice. Overall, these results indicate that selective loss of p53 in cardiomyocytes is not sufficient to prevent Dox induced myocardial ROS/RNS generation, apoptosis, interstitial fibrosis and perivascular fibrosis. Further, these results support a role for p53 independent apoptotic pathways leading to Dox induced myocardial damage and highlight the importance of vascular lesions in Dox induced cardiotoxicity

Spoil dump resloping at Fording River operations

Much research work has been done on the suitability of materials and the selection of plant species for revegetation purposes. This work is well documented and research is continuing. Limited work, however, has been done on the actual physical preparation of reclamation sites. Fording Coal Limited has undertaken research on optimum resloping techniques. The first phase of this work, completed in 1977, covered the physical resloping of waste dumps from the natural angle of repose (37°) to a range of slope angles from 26° to 34°. Associated costs were closely monitored to determine the effect of resloping requirements on the economics of spoil construction (formed versus free dump spoils). This paper discusses preliminary results of the resloping test work, specifically equipment limitations, economics of dump construction and planned follow-up work. Also discussed is the integration of these results with mine planning.Non UBCUnreviewedOthe

Follow-up slope experiments at Fording Coal Limited

Non UBCUnreviewedOthe