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At least 19 records

A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

This article describes the use of evaporation control lids that are fitted to crystallization plates to improve the reproducibility of trials using as little as 5 nl. The plate lids contain apertures which are large enough for the transfer of protein containing droplets, but small enough to greatly reduce the rate of evaporation during the time needed to prepare the plate. A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. The results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

MEMS packaging with etching and thinning of lid wafer to form lids and expose device wafer bond pads

In wafer-level packaging of microelectromechanical (MEMS) devices a lid wafer is bonded to a MEMS wafer in a predermined aligned relationship. Portions of the lid wafer are removed to separate the lid wafer into lid portions that respectively correspond in alignment with MEMS devices on the MEMS wafer, and to expose areas of the MEMS wafer that respectively contain sets of bond pads respectively coupled to the MEMS devices.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Instrumented Lid Detailed Design

This report describes the design of an instrumented lid assembly for remote sampling, monitoring, and radiation testing (SMART) for demonstration and surveillance of the dry storage environment and fuel conditions of aluminum clad spent nuclear fuel (ASNF) in a Department of Energy (DOE) standardized canister. The lid assembly consists of a custom-designed lid and hat, together with a custom fuel basket. The functions and designs of each component of the lid assembly and the general arrangement of the lid assembly are provided in this report. The Piping and Instrumentation Diagram for the corresponding instruments which will be connected to the lid assembly is shown in the appendix. Details of the system to provide characterization are provided in SRNL-L2240-2019-00002, "Instrumented Lid - System Final Design". The detailed drawings of the lid assembly will be prepared following the specification of the demonstration and surveillance system, including canister, design, to which the lid will be matched. Individual testing of the lid assembly sensor components will be performed in cold testing. The lid assembly including connection ports for gas sampling and thermowells will be fabricated. The tubing of the lid assembly to which the sensor components will be connected will not be assembled. The final design of the lid assembly connections to instrumentation is dependent on the staging of the demonstration and surveillance canister.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Molecular basis for dual functions in pilus assembly modulated by the lid of a pilus-specific sortase

The biphasic assembly of Gram-positive pili begins with the covalent polymerization of distinct pilins catalyzed by a pilus-specific sortase, followed by the cell wall anchoring of the resulting polymers mediated by the housekeeping sortase. In Actinomyces oris, the pilus-specific sortase SrtC2 not only polymerizes FimA pilins to assemble type 2 fimbriae with CafA at the tip, but it can also act as the anchoring sortase, linking both FimA polymers and SrtC1-catalyzed FimP polymers (type 1 fimbriae) to peptidoglycan when the housekeeping sortase SrtA is inactive. To date, the structure-function determinants governing the unique substrate specificity and dual enzymatic activity of SrtC2 have not been illuminated. Here, we present the crystal structure of SrtC2 solved to 2.10-Å resolution. SrtC2 harbors a canonical sortase fold and a lid typical for class C sortases and additional features specific to SrtC2. Structural, biochemical, and mutational analyses of SrtC2 reveal that the extended lid of SrtC2 modulates its dual activity. Specifically, we demonstrate that the polymerizing activity of SrtC2 is still maintained by alanine-substitution, partial deletion, and replacement of the SrtC2 lid with the SrtC1 lid. Strikingly, pilus incorporation of CafA is significantly reduced by these mutations, leading to compromised polymicrobial interactions mediated by CafA. In a srtA mutant, the partial deletion of the SrtC2 lid reduces surface anchoring of FimP polymers, and the lid-swapping mutation enhances this process, while both mutations diminish surface anchoring of FimA pili. Evidently, the extended lid of SrtC2 enables the enzyme the cell wall-anchoring activity in a substrate-selective fashion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

A retractable lid in lecithin:cholesterol acyltransferase provides a structural mechanism for activation by apolipoprotein A-I

Lecithin:cholesterol acyltransferase (LCAT) plays a key role in reverse cholesterol transport by transferring an acyl group from phosphatidylcholine to cholesterol, promoting the maturation of high-density lipoproteins (HDL) from discoidal to spherical particles. LCAT is activated through an unknown mechanism by apolipoprotein A-I (apoA-I) and other mimetic peptides that form a belt around HDL. Here, we report the crystal structure of LCAT with an extended lid that blocks access to the active site, consistent with an inactive conformation. Residues Thr-123 and Phe-382 in the catalytic domain form a latch-like interaction with hydrophobic residues in the lid. Because these residues are mutated in genetic disease, lid displacement was hypothesized to be an important feature of apoA-I activation. Functional studies of site-directed mutants revealed that loss of latch interactions or the entire lid enhanced activity against soluble ester substrates, and hydrogen–deuterium exchange (HDX) mass spectrometry revealed that the LCAT lid is extremely dynamic in solution. Upon addition of a covalent inhibitor that mimics one of the reaction intermediates, there is an overall decrease in HDX in the lid and adjacent regions of the protein, consistent with ordering. As a result, these data suggest a model wherein the active site of LCAT is shielded from soluble substrates by a dynamic lid until it interacts with HDL to allow transesterification to proceed.

59 BASIC BIOLOGICAL SCIENCES↗

The Crystal Structure Analysis of Group B Streptococcus Sortase C1: A Model for the ;Lid; Movement upon Substrate Binding

A unique feature of the class-C-type sortases, enzymes essential for Gram-positive pilus biogenesis, is the presence of a flexible 'lid' anchored in the active site. However, the mechanistic details of the 'lid' displacement, suggested to be a critical prelude for enzyme catalysis, are not yet known. This is partly due to the absence of enzyme-substrate and enzyme-inhibitor complex crystal structures. We have recently described the crystal structures of the Streptococcus agalactiae SAG2603 V/R sortase SrtC1 in two space groups (type II and type III) and that of its 'lid' mutant and proposed a role of the 'lid' as a protector of the active-site hydrophobic environment. Here, we report the crystal structures of SAG2603 V/R sortase C1 in a different space group (type I) and that of its complex with a small-molecule cysteine protease inhibitor. We observe that the catalytic Cys residue is covalently linked to the small-molecule inhibitor without lid displacement. However, the type I structure provides a view of the sortase SrtC1 lid displacement while having structural elements similar to a substrate sorting motif suitably positioned in the active site. We propose that these major conformational changes seen in the presence of a substrate mimic in the active site may represent universal features of class C sortase substrate recognition and enzyme activation.

59 BASIC BIOLOGICAL SCIENCES↗

Mass Transport Properties of LiD-U Mixtures from Orbital Free Molecular Dynamics Simulations and a Pressure-Matching Mixing Rule

Mass transport properties for LiD-U mixtures were calculated using a pressure matching mixture rule for the mixing of LiD and of U properties simulated with Orbital Free Molecular Dynamics (OFMD). The mixing rule was checked against benchmark OFMD simulations for the fully interacting three-component (Li, D, U) system. To obtain transport coefficients for LiD-U mixtures of different (LiD) x U (1-x) compositions as functions of temperature and mixture density is a tedious task. Quantum molecular dynamics (MD) simulations can be employed, as in the case LiD or U. However, due to the presence of the heavy constituent U, such simulations proceed so slowly that only a limited number of numerical data points in the (x, ρ, T) phase space can be obtained. To finesse this difficulty, transport coefficients for a mixture can be obtained using a pressure-matching mixing rule discussed. For both LiD and U, the corresponding transport coefficients were obtained earlier from quantum molecular dynamics simulations. In these simulations, the quantum behavior of the electrons was represented using an orbital free (OF) version of density functional theory, and ions were advanced in time using classical molecular dynamics. The total pressure of the system, P = nk β T/V + P e , is the sum of the ideal gas pressure of the ions plus the electron pressure. The mass self-diffusion coefficient for species α, D α , the mutual diffusion coefficient for species α and β, D αβ , and the shear viscosity, η, are computed from the appropriate autocorrelation function. The details of similar QMD calculations on LiH are described in Ref. [1] for 0.5 eV < T < 3 eV, and in Ref. [2] for 2 eV < T < 6 eV.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Monolithic LTCC seal frame and lid

A method for forming a monolithic seal frame and lid for use with a substrate and electronic circuitry comprises the steps of forming a mandrel from a ceramic and glass based material, forming a seal frame and lid block from a ceramic and glass based material, creating a seal frame and lid by forming a compartment and a plurality of sidewalls in the seal frame and lid block, placing the seal frame and lid on the mandrel such that the mandrel fits within the compartment, and cofiring the seal frame and lid block.

36 MATERIALS SCIENCE↗

Characterization of the lid-driven cavity magnetohydrodynamic flow at finite magnetic Reynolds numbers using far-field magnetic boundary conditions

The lid-driven cavity (LDC) flow is a canonic hydrodynamic problem. In this work, a 3D LDC flow of electrically conducting, incompressible fluid is studied numerically in the presence of a strong magnetic field, which is applied parallel to the lid plane and perpendicular to the direction of the lid motion. The cavity has electrically conducting walls of finite thickness and an infinitely thin moving lid. The problem is characterized by three dimensionless parameters: the Reynolds number ( Re ), the Hartmann number ( Ha ), and the magnetic Reynolds number ( Re m ). The primary research focus is on the effect of Re m , which was changed in the study from Re m $\ll$ 1 to the maximal Re m = 2000 at which dynamo action may be expected, while Ha = 100 and Re = 2000. The computational approach is based on the utilization of far-field magnetic boundary conditions by solving the full magnetohydrodynamic (MHD) flow problem at finite Re m for a multi-material domain composed of the inner conducting liquid, conducting walls, and sufficiently large insulating outer domain called “vacuum” (the induced magnetic field vanishes at the vacuum boundaries) using a fractional-step method. Lastly, the computed results show many interesting features with regard to the effect of Re m on the MHD boundary layer and the bulk flow, generation of a magnetic field and its penetration into vacuum, energy balance, tendency of the magnetic field to become frozen in the fluid and associated magnetic flux expulsion, transition to unsteady flows, and self-excitation of the magnetic field and the associated dynamo-type action at high Re m

42 ENGINEERING↗

Gold-Tin Solder Wetting Behavior for Package Lid Seals

This study examined the cause of nonwetted regions of the gold (Au) finish on iron-nickel (Fe–Ni) alloy lids that seal ceramic packages using the 80Au-20Sn solder (wt %, abbreviated Au–Sn) and their impact on the final lid-to-ceramic frame solder joint. The Auger electron spectroscopy (AES) surface and depth profile techniques identified surface and through-thickness contaminants in the Au metallization layer. In one case, the AES analysis identified background levels of carbon (C) contamination on the surface; however, the depth profile detected Fe and Ni contaminants that originated from the plating process. The Fe and Ni could impede the completion of wetting and spreading to the edge of the Au metallization. The Au layer of lids not exposed to a Au–Sn solder reflow step had significant surface and through-thickness C contamination. Inorganic contaminants were absent. Subsequent simulated reflow processes removed the C contamination from the Au layer without driving Ni diffusion from the underlying solderable layer. Finally, an Au metallization having negligible C contamination developed elevated C levels after exposure to a simulated reflow process due to C contamination diffusing into it from the underlying Ni layer. However, the second reflow step removed that contamination from the Au layer, thereby allowing the metallization to support the formation of lid-to-ceramic frame Au–Sn joints without risk to their mechanical strength or hermeticity.

36 MATERIALS SCIENCE↗

3013 Inner Can Lid Leak Test System Development

Contained in this report is a description of the 3013 inner container lid leak detection system, a listing of the data collected to validate the system and a statistical analysis of collected data. The 3013 Container Surveillance Program provides assessment criteria and evaluates 3013 containers selected from the storage inventory for potential degradation mechanisms. The 3013 outer container is the boundary credited to prevent release of material to the environment. The integrity of the outer container is only at risk if the inner container loses its seal and allows corrosive gases to diffuse into the outer container. To date, the determination of potential outer container exposure to corrosive gases has been through comparison of the gas analysis of the annular space and the inner container. If the two volumes have the same gas composition and pressure, then the inner container may have leaked. The leak detection system described in this report will provide a direct measurement of the integrity of the inner container, and if approved, will provide for the elimination of gas analysis. The inner container lid leak testing system consists of two basic parts: the Agilent leak testing instrument and the leak test fixture. The test fixture base provides the connection between the leak test instrument and the test sample. This connection allows helium to flow into the leak detector when a leak path exists in the test sample allowing leak measurement to be performed. The tests reported here were conducted in a cold lab using a configuration very similar, but not identical to, the configuration anticipated when installed in a glove box. A total of sixty-five leak rate measurements were made on 10 containers and the data is included in the report. The data analysis shows that the leak detection system can identify leaks in the lid, including the weld and heat affected zone of 3013 inner containers, during destructive examination. The measurements taken support that a 3013 IC lid with a leak rate value greater than 2.0 x 10 -7 atm cc/sec will be identified using the leak test system prior to introduction into a glove box. These results from the baseline for future tests of the leak test system after it is installed in the glove box for use as part of surveillance DE.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Stress and Strain Modeling of Low Temperature Cofired Ceramic (LTCC) Seal Frame and Lid

Low temperature cofired ceramic (LTCC) is established as an excellent packaging technology for high reliability, high density microelectronics. LTCC multichip modules (MCMs) comprising both ‘surface mount’ and ‘chip and wire’ technologies provide additional customization for performance. Long term robustness of the packages is impacted by the selection of seal frame and lid materials used to enclose the components inside distinct rooms in LTCC MCMs. An LTCC seal frame and lid combination has been developed that is capable of meeting the sealing and electromagnetic shielding requirements of MCMs. Here, we analyze the stress and strain performance of various seal frame and lid materials, sealing materials, and configurations. The application for the MCM will affect selection of the seal frame, lid, and sealing materials based on this analysis.

36 MATERIALS SCIENCE↗

Drum lid removal tool

A tool for removing the lid of a metal drum wherein the lid is clamped over the drum rim without protruding edges, the tool having an elongated handle with a blade carried by an angularly positioned holder affixed to the midsection of the handle, the blade being of selected width to slice between lid lip and the drum rim and, when the blade is so positioned, upward motion of the blade handle will cause the blade to pry the lip from the rim and allow the lid to be removed.

Pella, Bernard M↗

Fluor Idaho Technical Investigation-ARP V Lid Ejection Reactants and Mechanism - 19521

In April 2018, four 208.2-L (55-gal) drums containing transuranic waste at the Idaho National Laboratory Site became over-pressurized, resulting in lid ejection and expulsion approximately 50% of the contents. The parent drums were part of a retrieval effort and were exhumed from a portion of Subsurface Disposal Area Pits 11 and 12 beginning in 1974 and ending in 1978. Drums were later retrieved from the cargo containers, characterized using real-time radiography and nondestructive assay, and opened. The contents were visually inspected and repackaged into new 'daughter' drums within the Accelerated Retrieval Project V facility. Lid ejection occurred 7-12 hours after repackaging. The lid ejections were accompanied by significant heat generation. Empirical evidence of heat generation was observed in each reacted drum. The heat generated was sufficient to warp the high-density polyethylene liner (< 122 to 137 deg. C) in three of the drums and char the drum paint (∼400 deg. C) on one drum. To determine the potential reactant(s), a comprehensive chemical analysis was performed by two independent laboratories, Southwest Research Institute and Savannah River National Laboratory, on the reacted drum contents, ejected drum material, and related drums. A comprehensive chemical compatibility analysis was performed, and the most likely reactant(s) were identified. The oxidation of depleted uranium was the source of the heat generation. The presence of depleted uranium in the daughter drums and its chemical behavior (reactive properties and lack of visual indicators during packaging) are consistent with the event. The heat generated was sufficient to accelerate secondary chemical reactions leading to significant gas formation sufficient to generate pressures well in excess of the pressures needed to eject the lid and contents. These reactions fall into two categories: (1) simple volatilization of organics and water present in the drum and (2) hydrolysis of beryllium carbide, which generated significant quantities of methane gas. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Standard Waste Box Lid Screw Removal Option Testing

This report provides results from test work conducted to resolve the removal of screws securing the standard waste box (SWB) lids that hold the remediated nitrate salt (RNS) drums. The test work evaluated equipment and process alternatives for removing the 42 screws that hold the SWB lid in place. The screws were secured with a red Loctite thread locker that makes removal very difficult because the rivets that the screw threads into would slip before the screw could be freed from the rivet, making it impossible to remove the screw and therefore the SWB lid.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Instrumented Lid: Full Instrumentation System Testing

This report describes full system testing of an instrumentation system for the monitoring of aluminum clad spent nuclear fuel (ASNF). The requirements for this system were laid out in a previous document, with respect to former studies, and the details of project actualization were reported. The reader is directed to these references for more background information. In short, a team composed of personnel from Savannah River National Laboratory (SRNL) and Idaho National Laboratory have been tasked with the design and fabrication of an instrumented assembly for remote sampling, monitoring, and radiation testing (SMART) for demonstration and surveillance of the dry storage environment and conditions of ASNF in a DOE standardized canister. SRNL proposed the fabrication of two systems to accomplish this goal: 1) an instrumentation system consisting of gas and particle collection, temperature, humidity, pressure, and radiation monitoring; and 2) a lid assembly consisting of a custom-designed lid and hat, together with a custom fuel basket. The corresponding instrumentation system is shown in the piping and instrumentation diagram. The individual functionality tests of the instrument system sensor components were performed, and the results were reported in the report “Instrumented Lid- System Functionality Testing.” Savannah River National Laboratory, September 1, 2019.7 The sensor components of instrumentation system have been mounted and tested in-line with a 6” diameter test canister, and the results are reported in this document.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

LID and LeTID Impacts to PV Module Performance and System Economics: Draft Analysis

This webinar is a technical review of the measurements and causes of BO LID, UV LID and LeTID, as well as modeling their impacts to PV project financial metrics. We will first review how Boron-Oxygen complexes form and detail the range of impacts to PV module power ratings over time and across climates. Similarly, we will also discuss the measurements and extent of UV LID over time and across climates. Then, we will demonstrate a methodology for translating these effects to pro forma cash flow models and their impacts to PV project financial returns and levelized cost of electricity (LCOE). We will conclude with estimates of the value of solutions to these degradation mechanisms.

41 EE - Solar Energy Technologies Office (EE-4S)↗

An Open-Source Python Library for Modeling LETID and LID in Silicon Solar Cells and Wafers

This poster demonstrates an (in development) open-source software library, written in python, to aid in modeling and understanding light- and elevated temperature-induced degradation (LETID) and boron-oxygen light-induced degradation (B-O LID) in silicon solar cells and wafers. We discuss the underlying equations and necessary input parameters for constructing realistic models. We demonstrate several use cases for the library, including modeling LETID progression in scenarios like indoor, accelerated tests and outdoor field deployment. We also demonstrate using the library to model B-O LID, and we demonstrate using the library to model degradation in passivated wafers, rather than solar cells.

LETID↗