Experience in feeding coal into a liquefaction process development unit

A system for preparing coal slurry and feeding it into a high pressure liquefaction plant is described. The system was developed to provide supporting research and development for the Bureau of Mines coal liquefaction pilot plant. Operating experiences are included

Shangri La : architecture as collection

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2007.Includes bibliographical references (leaves 40-42).As a young heiress of the Duke fortunes, Doris Duke's interest and investment in art was not highly unusual given her social background. However, her method of acquiring these objects was more unconventional than other collectors of her time. When the term "Islamic" is tacked onto these art objects it further complicates her collection, with issues of matronage and Orientalism at the forefront. Prominent American collectors, such as Isabella Stewart Gardner, exhibited an interest in Eastern art long before Doris Duke planned her honeymoon trip to the Muslim world in 1935. Still, there is very little hard evidence of the Duke's interacting with such people during Doris' childhood. This begs the question, how did Doris Duke develop an interest in Islamic art and culture? Since she was a very private person and collector, it is hard to speculate what inspired her curiosity for Islamic art. What might be a more informative and interesting avenue to follow is the impressive network of connections that allowed her the means to acquire such a substantial collection. Her self-created residence in Hawai'i, Shangri La, is now a visible culmination of the relationships she forged in her fascination with Islamic art and architecture, which she continually developed from its inception in 1937 until her death in 1993.(cont.) Although Duke was highly dependent upon her advisors during the construction of Shangri La, she was purposeful in the procurement and placement of the objects she commissioned, which showed an independent will that varied from other wealthy American patrons of Eastern art at this time. An examination of these art-oriented relationships will help to trace the refinement of Duke's palette for Islamic art, whose chief architectural accomplishment was one that she truly thought of as Islamic and uniquely her own.by Saima J. Akhtar.S.M

Genetic bottlenecks during systemic movement of Cucumber mosaic virus vary in different host plants

AbstractGenetic bottlenecks are stochastic events that narrow variation in a population. We compared bottlenecks during the systemic infection of Cucumber mosaic virus (CMV) in four host plants. We mechanically inoculated an artificial population of twelve CMV mutants to young leaves of tomato, pepper, Nicotiana benthamiana, and squash. The inoculated leaves and primary and secondary systemically infected leaves were sampled at 2, 10, and 15 days post-inoculation. All twelve mutants were detected in all of the inoculated leaves. The number of mutants recovered from the systemically infected leaves of all host species was reduced significantly, indicating bottlenecks in systemic movement. The recovery frequencies of a few of the mutants were significantly different in each host probably due to host-specific selective forces. These results have implications for the differences in virus population variation that is seen in different host plants

Authoritarian leadership and cyberloafing: A moderated mediation model of emotional exhaustion and power distance orientation

Drawing upon the conservation of resource theory (COR), this study proposes a moderated mediation model of authoritarian leadership on subordinates’ cyberloafing. Paired samples of 360 employees working in 103 teams from Chinese companies were collected at 2 points in time. The results show that authoritarian leadership positively affects subordinates’ cyberloafing and this relationship is mediated by emotional exhaustion. Furthermore, power distance orientation negatively moderates the relationship between authoritarian leadership and emotional exhaustion and also negatively moderates the indirect effect of authoritarian leadership on subordinates’ cyberloafing through subordinates’ emotional exhaustion. Our findings expand and enrich the literature on authoritarian leadership and cyberloafing and have significant practical implications for managing employees in this digital era

Skyrmion morphology in ultrathin magnetic films

Nitrogen-vacancy magnetic microscopy is employed in quenching mode as a non-invasive, high resolution tool to investigate the morphology of isolated skyrmions in ultrathin magnetic films. The skyrmion size and shape are found to be strongly affected by local pinning effects and magnetic field history. Micromagnetic simulations including static disorder, based on a physical model of grain-to-grain thickness variations, reproduce all experimental observations and reveal the key role of disorder and magnetic history in the stabilization of skyrmions in ultrathin magnetic films. This work opens the way to an in-depth understanding of skyrmion dynamics in real, disordered media.Comment: 9 pages, 8 figures, including supplementary information

Impact of dissolution of cast tungsten carbide on the wear behavior of CTC/Ni metal matrix composites

Cast tungsten carbide (CTC) consists in a biphasic structure of WC lamellae in a W2C matrix resulting from the eutectoid decomposition of W-3.9 wt.% C. Hardfacing of steel tools is the main industrial application of CTC powders, where metal matrix composite (MMC) wear-resistant overlays are deposited by means of conventional welding techniques. Self-fluxing nickel alloys are the most commonly used matrix materials for dispersed CTC particulate reinforcing phase. Overall performance and mechanical integrity of these overlays is affected by dissolution of CTC particles into the matrix phase due to high processing temperature. In this study, a powder blend containing 60 wt. % spherical CTC (71-150 μm) + 40 wt. % Ni-based matrix was used to deposit hardfacing overlays onto tool steel substrate by means of laser cladding. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) revealed significant dissolution of WC into the surrounding matrix for all specimens. Reprecipitated W-rich carbide crystals ranged from fine and rather equiaxed for low energy input, to coarse and highly dendritic for high energy input. In a quest for completely avoiding dissolution of CTC particles, spark plasma sintering (SPS) was used to consolidate substrate-free CTC/Ni MMCs with significantly lower energy input and reasonably high cooling rate. SEM and EDS investigation of SPS-sintered MMCs revealed no WC dissolution followed by reprecipitation of W-rich carbides. Fracture toughness was estimated by means of microindentation fracture, and tribological testing was used to evaluate the impact of reprecipitated crystals on the wear behavior of CTC/Ni MMC’s

Influence of Natural Zeolite and Mineral additive on Bacterial Self-healing Concrete: A Review

With time, the development of micro-cracks in concrete is a frequently reported problem in the structures due to the ingress of harmful substances, leading to the degradation of its quality and strength, which ultimately declines the construction. The present work is a review paper based on enhancing the self-healing property of concrete by inducing different bacteria alone or incorporating different mineral additives. It has been seen that various rehabilitated methodologies are in queue to surmount concrete’s weaknesses and to increase its strength and durability. The latest methodology includes using non-pathogenic microbes in concrete as Microbial induced Calcium Carbonate Precipitation (MICCP). The property of precipitating calcium carbonate (CaCO3) crystals by their metabolic activities helps repair the cracks in harsh conditions and improve their strength. Ureolytic bacteria like Bacillus pasteurii/Sporosarcina pasteurii, Bacillus subtilis, Bacillus megaterium, etc., have a specific property by which they can excite urea when integrated with a calcium source and help in sealing the cracks by CaCO3 precipitation. Different studies have observed that specimens having a bacterial concentration of 105-107 cells/ml with Natural Zeolite (NZ) replacement (10%) represents better interaction of the microstructure of concrete because of the formation of calcium silicate hydrate (CSH) gel. Further, the reduction in CH bond with reduced pore space has also been observed. NZ alone enhances micro-structural property, but it shows CaCo3 precipitation and more densification of microstructure under bacterial combination. XRD also confirms an increase in the calcite composition when the bacterial concentration of 105-107 cells/ml is used. The overall properties of standard and high-strength bacterial concrete (105-107 cells/ml) with 10% Natural Zeolite replacement can provide a better option for the future of sustained and strong concrete. Doi: 10.28991/CEJ-2022-08-05-015 Full Text: PD