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Effects of long-range transport of air pollutants on Arctic cloud-active aerosol, The

May 1983.Includes bibliographical references.Sponsored by Dept. of Atmospheric Science, Colorado State University.Sponsored by Graduate School of Oceanography, University of Rhode Island.Sponsored by National Science Foundation ATM-7819261.Sponsored by National Science Foundation ATM-8109490.Sponsored by Office of Naval Research N00014-76-C-0435

Ensemble Concerts: The Renaissance Ensemble, November 21, 1974

Centennial East Recital HallThursday EveningNovember 21, 19747:00 p.m

Evaluating inventory segmentation strategies for aftermarket service parts in heavy industry using linked discrete-event and Monte Carlo simulations

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Vita. Cataloged from PDF version of thesis.Includes bibliographical references (p. 104-106).Heavy industries operate equipment having a long life to generate revenue or perform a mission. These industries must invest in the specialized service parts needed to maintain their equipment, because unlike in other industries such as automotive, there is often no aftermarket supplier. If parts are not on the shelf when needed, equipment sits idle while replacements are manufactured. Stock levels are often set to achieve an off-the-shelf fill rate goal using commercial inventory optimization tools, while supply chain performance is instead measured against a speed of service metric such as order fulfillment lead time, the time from order placement to customer receipt. When some parts are more important than others, and shipping delays are accounted for, there is ostensibly little correlation between these two metrics and setting stock levels devolves into an inefficient and expensive guessing game. This thesis resolves the disconnect between stock levels and service metrics performance by linking an existing discrete-event simulation of warehouse operations to a new Monte Carlo demand categorization and metrics simulation, predicting tomorrow's supply chain performance from today's logistics data. The insights gained here through evaluating an industry representative dataset apply generally to supply chains for aftermarket service parts. The simulation predicts that the stocking policy recommended by a simple strategy for inventory segmentation for consumable parts will not achieve the desired service metrics. An internal review board that meets monthly, and a quarterly customer acquisition policy, each degrade performance by imposing a periodic review policy on stock levels developed assuming a continuous review policy. This thesis compares the simple strategy to a sophisticated strategy for inventory segmentation, using simulation to demonstrate that with the latter, metrics can be achieved in one year, inventory investment lowered 20%, and buys for parts in low annual usage categories automated.by Randolph L. Bradley.M.Eng.in Logistic

An Environmentally Friendly Conductive Ink Made Using Transgenic Spider Silk Protein and Silver Salts

The goal of this study was to demonstrate that it is possible to formulate an electrically conductive, stretchable and environmentally friendly ink or coating. This is made possible by harnessing the properties of biomimetic spider silk obtained from transgenic goats. In this experiment we formulated four inks using spider silk, silver trifluoroacetate and carbon nanotubes (CNT). We utilized Polyethylene terephthalate (PET), spider silk, natural rubber (Latex) and polystyrene-block-isobutylene-block-styrene(SIS) as substrates to demonstrate the flexible nature of the ink/coating. We then conducted surface characterization using FTIR and SEM to verify the presence of our coating and quantified the thickness of our coatings. We measured the conductivity of the ink using an Ohm meter. Our preliminary results indicate successful formulation of an ink that meets the parameters described above. Inks formulated using spider silk and AgTFA are in fact more stable and conductive than other inks tested in this experiment. We also found little or no success with the other three inks described in the experiment. This study serves as a proof of concept and starting point for optimization of such inks for use in the bio medical and technology sectors

Improving the PCR protocol to amplify a repetitive DNA sequence

Although PCR-based techniques have become an essential tool in the field of molecular and genetic research, the amplification of repetitive DNA sequences is limited. This is due to the truncated nature of the amplified sequences, which are also prone to errors during DNA polymerase-based amplification. The complex structure of repetitive DNA can form hairpin loops, which promote dissociation of the polymerase from the template, impairing complete amplification, and leading to the formation of incomplete fragments that serve as megaprimers. These megaprimers anneal with other sequences, generating unexpected fragments in each PCR cycle. Our gene model, MaSp1, is 1037-bp long, with 68% GC content, and its amino acid sequence is characterized by poly-alanine-glycine motifs, which represent the repetitive codon consensus. We describe the amplification of the MaSp1 gene through minor changes in the PCR program. The results show that a denaturation temperature of 98°C is the key determinant in the amplification of the MaSp1 partial gene sequence

Making Electrospun Spider Silk Fibers Stronger

Spider silk is one of the most robust and versatile fibers making it a topic of interest in the scientific community. Possessing strength and elasticity many have sought to create fibers comparable to natural spider silk. Up until recently many scientists have fallen short of creating said fibers. With the use of a technique called electrospinning, comparable spider silk fibers have been created. Electrospinning is the process of creating fibers from a polymer solution using an electrical field. This method leads to the formation of nanofibers. These Fibers can then be further modified by crosslinking, a technique traditionally used to analyze protein-protein interactions

Relative age of interior layered deposits in southwest Candor Chasma based on high-resolution structural mapping

High-resolution topography generated from stereo HiRISE (High-Resolution Imaging Science Experiment) imagery reveals the meter-scale structure of interior layered deposits (ILD) in southwest Candor Chasma. This study seeks to determine the age of the local ILD relative to any normal faults that can be attributed to chasma formation. The study area is located near the contact of these ILD and the wall rock and is in an area where chasma-forming normal faults have been proposed. We find that while normal faults are found in the study area, these faults are not sufficiently large nor appropriately located or oriented to accommodate the roughly northeast-southwest extension that is required for normal faults that can be attributed to chasma formation. Additionally, bedding exposed in the local ILD generally dips toward the center of Candor Chasma, consistent with sediment deposition in a preexisting basin. Further, pit craters of Tithonia Catena, presumed to predate or be contemporaneous with the formation of west Candor Chasma, do not cut into the ILD within the study area. These independent lines of evidence support a postchasma age for the ILD exposed within the study area. Chasma-related normal faults may exist within these ILD at depth but are not exposed at the surface. Approximately 2 km of conformable stratigraphy is exposed in the study area, and therefore at least several kilometers of the local ILD were deposited subsequent to any chasma-related normal faulting that may have occurred in this part of Candor Chasma

Large Scale Production of Spider Silk Protein in E. coli

Spider silks have long been a focus of research due to their remarkable mechanical properties including strength, toughness and elasticity. Moreover, biodegradability and biocompatibility of spider silks make them beneficial to use in biomedical applications. Spiders cannot be farmed because of their territorial and cannibalistic nature. Hence, production of recombinant spider silks is the only feasible solution for large scale production Large scale production is still challenging due to the small recombinant protein size, low yield and low water solubility of bio-synthetic spider silk. The current study reports our progress as well as evolution of effective protocol for large scale bio-synthetic production of spider silk protein in E. coli. Our main spidersilk protein we seek to produce and purify in a large scale is MaSp2. Spider dragline silk is primarily composed of proteins called major ampullate spidroins (MaSps) that consist of a large repeat array flanked by nonrepetitive N- and C- terminal domains. All MaSp genes are co-expressed in the major ampullate gland of Nephila Clavipes