731 research outputs found
Validation of the use of LEU uranium as a replacement for HEU in United States submarine reactors
No full textThesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 153-160).The US Navy has long used highly enriched uranium (HEU) in naval reactors for a variety of technical reasons. In a series of studies, the Department of Naval Reactors determined that switching to low enriched uranium (LEU) was impossible using current fuel designs, but may be possible with a dedicated program to investigate new fuel materials. This thesis simulated an HEU fueled submarine reactor using a uranium oxide-zirconium dispersion fuel, and compared it to an LEU reactor using a uranium-molybdenum alloy fuel. The required energy output of an attack submarine was used to set the burnup requirement of the HEU (333 MWd/kg) and LEU (93.5 MWd/kg) fueled reactors, and each reactor was depleted to the end of life. The results showed that naval reactors could be switched to LEU without sacrificing the lifetime submarine core or increasing reactor volume. Even if unstudied technological details render this impossible, an LEU core would require only a single refueling over the life of an attack submarine. This would necessitate a 3.25% increase in submarine fleet size, which is small compared to the average Department of Defense project cost overrun.by Brendan Patrick Hanlon.S.M
History of Leu Tribe
No full textDescribes the social makeup of the Leu Tribe and how it is divided into twelve smaller groupsDate unknown
Leu-Enkephalin Lipid Prodrug Nanoparticles: Relationship between Nanoparticles’ Structure, Interaction with Bovine Serum Albumin, and Analgesic Activity
No full textRecently,
we proposed in a paper a novel nanomedicine approach
based on a versatile bioconjugation linkage (amide, diglycolate, or
acylal) between the Leu-enkephalin (LENK), an endogenous neuropeptide,
and the squalene (SQ), a natural and biocompatible lipid. The nanoformulation
of the resulting bioconjugates allowed the specific delivery of LENK
into inflamed tissues for efficient pain control after their intravenous
administration. However, the variability of the analgesic profiles
exhibited by the three types of LENK-SQ nanoparticles (NPs) remains
not well understood. This study investigates the influence of the
LENK-SQ NP composition on their supramolecular organization and their
interaction with blood proteins. To achieve this objective, a physicochemical
study was carried out using complementary techniques such as dynamic
light scattering (DLS), small/wide-angle X-ray and neutron scattering
(SAXS-WAXS and SANS), and circular dichroism (CD). This study brought
together some important information, allowing us to shed light on
the crucial link between nanoparticles’ structure, stability,
and analgesic activity
Notes on the Thai Leu of the Ta Fa, Bokeo
No full textHandwritten notes describing the Thai Leu of Ta Fa, Bokeo and an English description of the blessings requires for the rice Baci Ceremony
Structural Basis for Differences in Dynamics Induced by Leu Versus Ile Residues in the CD Loop of Kir Channels
No full text
The effect of the conserved Leu/Ile site in the CD loop on the gating dynamics of Kir channels and corresponding micro-structural mechanism remains unclear. Molecular dynamics simulations were performed to investigate the structural mechanism of chicken Kir2.2. Compared to WT, the I223L mutant channel bound to PIP2 more strongly, was activated more rapidly, and maintained the activation state more stably after PIP2 dissociation. Cellular electrophysiology assays of mouse Kir2.1 and human Kir2.2 indicated that, consistent with simulations, the Leu residue increased the channel responses to PIP2 through increased binding affinity and faster activation kinetics, and the deactivation kinetics decreased upon PIP2 inhibition. The Ile residue induced the opposite responses. This difference was attributed to the distinct hydrophobic side chain symmetries of Leu and Ile; switching between these residues caused the interaction network to redistribute and offered effective conformation transduction in the Leu systems, which had more rigid and independent subunits.</p
Die Zwiesprach der Tiere
No full textHere is a lovely book with bent covers presenting many vignettes of animals. The book is a nostalgic reproduction of 38 fables from a Dialogus Creaturarum of 1480. The woodcuts are charming as they present a variety of creatures in dialogue with each other. To my surprise, only one of the fables is one of those we know well: "The Angler and Small Fish" (27). The typeface is also a throwback to earlier German publishing. I will include Peter Everaers' comments: "Die Zwiesprach der Tiere. München, Verlag der Münchner Drucke, 1923. Original decorated board, 77+1p. Ca. 23 x 15,5 cm. "Von einem Unbekannten im späten Mittelalter in Holland geschrieben, wurden viele Fabeln zuerst im Jahr 1480 von Peter van Leu in Gouda gedruckt. Nach diesem Dialogus Creaturarum liesz der Verlag der Münchener Drucke in München im Jahr 1923 die schönsten Fabeln aus dem Lateinischen übersetzen und in den alten Huttlerschen Typen der Offizin G.J. Manz A.-G. in München drucken. Dem holländischen Frühdruck sind auch die achtunddreiszig Holzschnitte entnommen. Nr. 262/550." Some staining in the last pages; boards somewhat discoloured; otherwise a good copy."Language note: German#262 of 550No Autho
Investigation of multi-device location spoofing attacks on air traffic control and possible countermeasures
No full textMultilateration techniques have been proposed to verify the integrity of unprotected location claims in wireless localization systems. A common assumption is that the adversary is equipped with only a single device from which it transmits location spoofing signals. In this paper, we consider a more advanced model where the attacker is equipped with multiple devices and performs a geographically distributed coordinated attack on the multilateration system. The feasibility of a distributed multi-device attack is demonstrated experimentally with a self-developed attack implementation based on multiple COTS software-defined radio (SDR) devices. We launch an attack against the OpenSky Network, an air traffic surveillance system that implements a time-difference-of-arrival (TDoA) multi-lateration method for aircraft localization based on ADS-B signals. Our experiments show that the timing errors for distributed spoofed signals are indistinguishable from the multilateration errors of legitimate aircraft signals, indicating that the threat of multi-device spoofing attacks is real in this and other similar systems. In the second part of this work, we investigate physical-layer features that could be used to detect multi-device attacks. We show that the frequency offset and transient phase noise of the attacker's radio devices can be exploited to discriminate between a received signal that has been transmitted by a single (legitimate) transponder or by multiple (malicious) spoofing sources. Based on that, we devise a multi-device spoofing detection system that achieves zero false positives and a false negative rate below 1%
Enzymatic peptide synthesis in low water content systems : Preparative enzymatic synthesis of [Leu]- and [Met]-enkephalin derivatives
No full textA novel total enzymatic synthesis of [Leu]- and [Met]-enkephalin derivatives was accomplished in low-water content systems at a preparative scale. α-Chymotrypsin, papain, thermolysin and bromelain adsorbed on Celite were used as catalysts. Organic solvents such as acetonitrile and ethyl acetate with small amounts of buffer added or at specific water activity were used as reaction media. Simple readily available amino acid ester derivatives were used as starting building blocks. This feature allowed the possibility of using the products in one step directly as acyl-donor ester, without any chemical or enzymatic modification, in the next enzymatic coupling. The optimal strategy for the synthesis of the enkephalin derivatives was different depending on the carboxy terminal group. The preparation of the carboxy-terminal amide derivatives (R-Tyr-Gly-Gly-Phe-Leu[Met]-NH2) was achieved via 4 + 1 fragment condensation catalyzed by α-chymotrypsin. The carboxy-terminal ethyl ester derivatives (R-Tyr-Gly-Gly-Phe-Leu[Met]-OEt) were obtained via 2 + 3 condensation catalyzed by bromelain, a quite unusual protease for peptide synthesis but more effective than papain in this coupling. Both syntheses were carried out in four enzymatic steps and one or two chemical deprotection steps routinely used in peptide synthesis. The overall yields of pentapeptide derivatives were between 40-54% of pure product
Isoantigens ABH in bladder tumors as an indicator of malignant potential: a combined study with CEA, BMG, Leu-M1 and H-Ag
No full text初発表在性膀胱腫瘍43例を対象に, 免疫組織化学的手法にてBGA, CEA, BMG, Leu-M1, H-Agを検索した.1)同一組織におけるBGA, CEA, BMG, Leu-M1, H-Agの染色性に関しては, 相互に明らかな関連性は認められなかった.2) BGA, CEA, Leu-M1は, それぞれ単独でmalignant potentialの指標となるうるが, その中では特にBGAの有用性が最も高かった.3) BGAを基本とするBGAとLeu-M1の併用は, BGA単独に比して, より客観的な予後予測法と考えられ, 新しい判定法を提唱したThe author performed immunohistochemical staining of blood group antigen (BGA), CEA, BMG, Leu-M1 and H-Ag on 43 patients with primary superficial bladder tumor to evaluate the malignant potential of bladder tumor. There were no obvious relationships among reactivities to BGA, CEA, BMG, Leu-M1 and H-Ag in identical tissue. Although BGA, CEA and Leu-M1 could be used individually as indicators of malignant potential, of the three, BGA was found to be most useful. Concomitant use of Leu-M1 with BGA might compensate for the disadvantages of BGA alone and make prediction of prognosis more objective. Then, a new evaluation criteria for detecting malignant potential of bladder tumor was proposed
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