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Silk and cotton : textiles from the Central Asia that was
The traditional textiles of Central Asia are an unknown treasure, now revealed in this book. Straddling the legendary Silk Road, this vast region stretches from the Caspian Sea in the west to the Gobi Desert in the east and is home to hundreds of tribes. Whether nomadic or sedentary, its peoples created textiles that related to every aspect of their way of life, from ceremonial objects marking rites of passage to everyday garments to practical items for the home. There were suzanis for the marriage bed; niche covers; prayer mats; patchwork bedding quilts; camel trappings for Turkmen bridal processions; bags for tea, scissors and mirrors; lovingly embroidered children's hats and bibs and robes of every colour and pattern. Author Susan Meller has spent years assembling the extraordinary collection of 590 textiles illustrated in this book. She documents their history, use and meaning.
Book
Comparative transcriptomics as a guide to natural product discovery and biosynthetic gene cluster functionality
Bacterial natural products remain an important source of new medicines. DNA sequencing has revealed that a majority of natural product biosynthetic gene clusters (BGCs) maintained in bacterial genomes have yet to be linked to the small molecules whose biosynthesis they encode. Efforts to discover the products of these orphan BGCs are driving the development of genome mining techniques based on the premise that many are transcriptionally silent during normal laboratory cultivation. Here, we employ comparative transcriptomics to assess BGC expression among four closely related strains of marine bacteria belonging to the genus Salinispora. The results reveal that slightly more than half of the BGCs are expressed at levels that should facilitate product detection. By comparing the expression profiles of similar gene clusters in different strains, we identified regulatory genes whose inactivation appears linked to cluster silencing. The significance of these subtle differences between expressed and silent BGCs could not have been predicted a priori and was only revealed by comparative transcriptomics. Evidence for the conservation of silent clusters among a larger number of strains for which genome sequences are available suggests they may be under different regulatory control from the expressed forms or that silencing may represent an underappreciated mechanism of gene cluster evolution. Coupling gene expression and metabolomics data established a bioinformatic link between the salinipostins and their associated BGC, while genetic manipulation established the genetic basis for this series of compounds, which were previously unknown from Salinispora pacifica.
Journal Article
Comparison of Rare Earth Refinement in 4130 and HY100
Solidification based grain refinement has gained wide interest by both researchers and industry. This method provides a route for refinement in processes where thermomechanical approaches are ineffective. Prior research into 4130 and HY100 found very different responses when rare earth additions were made. The 4130 was effectively refined while HY100 showed no response. The cause of this difference was not determined. The research presented in this paper examined heats of 4130 and HY100 with rare earth silicide or EGR additions. Characterization included macrostructure examination, mechanical testing, thermal analysis, and electron microscopy. Refinement was observed only in the treated 4130 heats and corresponded to an increase in the peritectic temperature. The HY100 heats had no changes in macrostructure or solidification reactions. Rare earth containing inclusions of similar compositions were observed in the treated 4130 and HY100 heats. These inclusions appear to be a good fit for austenite based on the 4130 data. It was proposed that the unresponsiveness of HY100 was due to the strong segregation of nickel before the peritectic in that alloy. Nickel promotes austenite, and its segregation may provide a stronger driving force for its formation than the energy barrier reduction caused by the presence of rare earth inclusions.
Journal Article
Alloy Steels
Since their invention in 1865, alloy steels have found broad application in multiple industries; the automotive, aerospace, heavy equipment, and pipeline industries to name a few[...]
Journal Article
Thermal Analysis Experiments in Titanium and Magnesium Additions to 4130 Steel
Titanium and magnesium additions singly and together were examined in 4130. A thermal analysis system measured the cooling rate of molten steel samples. These curves were analyzed for changes in phases evolved and phase reactions. The samples were also sectioned to determine the solidification structure. All additions refined the structure; however, magnesium and titanium additions together resulted in the finest structure. The peritectic reaction temperature was found to decrease with the additions. This decline may indicate an increase in the δ-ferrite stability due to favorable nucleation of that phase. The solidus temperature also appeared to decline. Inclusion analysis found TiN particles in the magnesium/titanium-containing sample. Only titanium-containing oxides were observed in the titanium-only samples. It appeared that the addition of magnesium made the formation of TiN more favorable.
Journal Article
Effect of Rare Earth Master Alloys on 4130
This paper documents a series of experimental 4130 heats that had additions of rare earth master alloys with different rare earth oxide inclusions. Once melted, the heats were poured into keel block castings for mechanical testing and metallographic examination. Additionally, a single-thermocouple thermal analysis system was employed to examine the solidification reactions of each heat. Several interesting observations were made. First, the mechanical properties and solidification structure of the heats were similar, contrary to earlier work in 4130. Thermal analysis noted that the liquidus and peritectic did not shift with the master alloy additions. Inclusion characterization found that the inclusions in the final castings were significantly different from the ones in the master alloys. These inclusions contained low or no sulfur in them. Based on this, the author concludes that sulfur-containing rare earth inclusions are the likely nuclei in steels. This work identifies several important factors in the grain refinement of 4130. Not all rare earth inclusions cause refinement, supporting the conclusion by many that specific rare earth inclusions refine a steel’s structure by acting as heterogeneous nuclei. Sulfur-containing inclusions may be the compounds that are acting in this role. Additionally, shifts in the peritectic temperature appear related to the occurrence of refinement. No refinement in this work occurred, and no peritectic shift happened either. Other work in the literature observed an increase in the peritectic temperature and the onset of refinement. The peritectic reaction appears to play a role in steel solidification refinement.
Journal Article
Experimental Grain Refiners for Carbon Steels
A series of master alloys designed to make rare earth oxide, rare earth aluminum oxide, or rare earth sulfide inclusions were created to determine which inclusions acted as heterogeneous nuclei. Plate test castings having additions of the various master alloys were produced to understand the refinement produced and the mechanical properties. The plates underwent tensile testing and metallographic analysis. For comparison, no addition and rare earth silicide addition heats were also poured. The rare earth oxide and sulfide master alloys formed the intended inclusions. The rare earth aluminum oxide master alloy had very poor homogeneity and contained inclusions with far lower aluminum contents than intended. Only the rare earth silicide reduced the grain size, resulting in improved mechanical properties. This would indicate that simple oxides or sulfides do not play a significant role in the nucleation in steel, but the more complex oxides and probably oxysulfides play the dominate roles.
Journal Article
Casting Simulation of Calcium Titanate and Calcium Zirconate Nozzles for Continuous Casting of Aluminum-Killed Steels
The clogging of submerged entry nozzles (SENs) and tundish well nozzles is a common problem in the continuous casting of aluminum-killed steels. Clogging occurs when alumina attaches to the inside of the nozzle restricting the flow. This article explores the use of new nozzle materials that could prevent accretion growth through the formation of liquid phases at the inclusion-refractory interface. Casting simulation experiments were conducted using three nozzle refractory formulations: calcium titanate, calcium zirconate, and a 2:1 calcium titanate to calcium zirconate molar mixture. Nozzles fabricated from these materials cast more aluminum-killed steel without clogging than typical industrial alumina graphite nozzles. However, the nozzles constructed of calcium titanate dramatically outperformed alumina graphite, calcium zirconate, and the mixed nozzles. Microscopy investigation of spent nozzles found no accretion formation in the calcium titanate nozzles. The performance difference was due to the formation of a liquid calcium aluminum titanate phase, which prevented alumina accretions.
Journal Article
Self-Employment, Work–Family Fit and Mental Health Among Female Workers
We used the 2002 National Study of the Changing Workforce to investigate the effects of work type on women’s lives. Specifically, we hypothesized that self-employed women have better work–family fit than organizationally employed women. We also hypothesized that as a result of better work–family fit, self-employed women would report better mental health than organizationally employed women. The analysis shows limited support for the hypotheses. Of the different dimensions of work–family fit, self-employment directly influenced only job to home facilitation. Work type had no direct influence on mental health. It appears that work type may indirectly influence work–family fit and mental health through higher job satisfaction and increased autonomy.
Journal Article
Study of Electrolytic Dissolution in Steels and Rare Earth Oxide Stability
Improving the mechanical properties of steels requires an accurate knowledge of inclusions’ shape and size. This work examined the dissolution rate of 1030 steel for two electrolytic solutions and the stability of several oxides. The dissolution rate was compared between two electrolytes (2 % TEA and 10 % AA) for up to 16 h. Also, the study of oxide stability in 2 % TEA was performed. Standard pure oxide powders such as Al2O3, NbO, NbO2, La2O3, and CeO2 were tested by adding 1 g each in 2 % TEA, while it was dissolving a test steel sample for 24 h. In this study, the actual weight of oxides was analyzed by the difference in weight before and after the electrolytic test run. It was observed that NbO and Al2O3 weighed 0.95 and 0.97 g after the electrolytic test, whereas other oxides were more stable during the electrolytic extraction. The stability test indicates that rare earth oxides are stable enough without dissolving and this helps in studying the rare earth inclusions morphology after extracting steel samples.
Journal Article