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At least 631 records · Page 35

Assessment and Improvement Proposals for High-Pressure Rinsing Processes during Cleanroom Preparation of Superconducting Radio-Frequency Cavities for Particle Accelerators

The goal of this internship is to develop a fluid dynamics characterization of the high-pressure flow used for cleaning the internal surface of the SRF cavities. Initially, the High Pressure Rinsing (HPR) process is introduced, focusing on the problems of the SRF cavities and how this method can be used to increase their acceleration efficiency and performance. The characterization of the problem is then presented, including an introduction to the multiphase flow modeling and the analysis of the Fermilab facility for the HPR. To accomplish the goal, a preliminary estimation of the variables was performed using MATLAB. Then, multiple 2D simulations were developed with Ansys Fluent, and the influence of the main parameter was investigated. The simulation results are then presented and analysed, with a focus on the possible future developments of the HPR process fluid dynamic characterization.

43 PARTICLE ACCELERATORS↗

Preparing California’s Cap-and-Trade Program for 2045: Integrating Carbon Dioxide Removal

To meet California’s legislatively mandated 2045 carbon neutrality target (AB 1279, Muratsuchi), analyses from the California Air Resources Board (CARB) and Lawrence Livermore National Laboratory (LLNL) have shown that carbon dioxide removal—activities that permanently remove carbon dioxide (CO 2 ) from the atmosphere—will be necessary to remove greenhouse gas emissions that are otherwise too costly or difficult to reduce. This policy brief explores the policy, legal, and technical considerations for integrating carbon dioxide removal into the Cap-and-Trade Program.

54 ENVIRONMENTAL SCIENCES↗

Cavity Preparation and Assembly: Challenges and Future R&D Directions

This presentation described the state of the art in cavity string assembly for the LCLS-II, HE, and PIP-II projects, as well as cavity performance statistics. The presentation also described the knowledge gap, opportunities for improvement, and future R&D recommendations.

Wu, Genfa [Fermilab]↗

Cavity Preparation and Assembly: Challenges and Future R&D Directions

This presentation described the state of the art in cavity string assembly for the LCLS-II, HE, and PIP-II projects, as well as cavity performance statistics. The presentation also described the knowledge gap, opportunities for improvement, and future R&D recommendations.

Wu, Genfa [Fermilab]↗

Capsule Design and Preparation for YH x Specimen Irradiation in the High Flux Isotope Reactor

Advanced nuclear systems for terrestrial microreactors and space applications require moderator materials with high thermal stability, hydrogen retention, and efficient neutron moderation. Yttrium hydride (YH x ) is a promising candidate, but its irradiation performance and hydrogen stability remain insufficiently understood. To address this, Oak Ridge National Laboratory (ORNL) and Los Alamos National Laboratory, supported by the US Department of Energy’s Nuclear Science User Facilities program, have initiated an irradiation campaign in ORNL’s High Flux Isotope Reactor. The experiment employs six irradiation capsules containing YH x specimens (H/Y ≈ 1.9) designed for three target temperatures (300°C, 400°C, and 500°C) and two distinct neutron fast fluence levels. This report documents the irradiation test matrix, capsule design, specimen precharacterization, and experiment readiness for insertion. Planned postirradiation examinations will provide new insights into hydrogen retention and microstructural stability, advancing the understanding of YH x as a moderator for compact reactor applications.

36 MATERIALS SCIENCE↗

Capsule Design and Preparation for YH x Specimen Irradiation in the High Flux Isotope Reactor

Advanced nuclear systems for terrestrial microreactors and space applications require moderator materials with high thermal stability, hydrogen retention, and efficient neutron moderation. Yttrium hydride (YH x ) is a promising candidate, but its irradiation performance and hydrogen stability remain insufficiently understood. To address this, Oak Ridge National Laboratory (ORNL) and Los Alamos National Laboratory, supported by the US Department of Energy’s Nuclear Science User Facilities program, have initiated an irradiation campaign in ORNL’s High Flux Isotope Reactor. The experiment employs six irradiation capsules containing YH x specimens (H/Y ≈ 1.9) designed for three target temperatures (300°C, 400°C, and 500°C) and two distinct neutron fast fluence levels. This report documents the irradiation test matrix, capsule design, specimen precharacterization, and experiment readiness for insertion. Planned postirradiation examinations will provide new insights into hydrogen retention and microstructural stability, advancing the understanding of YHx as a moderator for compact reactor applications.

36 MATERIALS SCIENCE↗

Preparing large area of thermochromic nanocomposite films for smart window application

The challenges posed by high building energy bill necessitate proactive implementation of energy-efficient strategies to minimize the uses of both electricity and heating gas and promote the use of free solar energy sources. "Smart" window films/glass, leveraging thermochromic vanadium dioxide (VO 2 ), offer an adaptive approach to harness solar energy, significantly reducing the thermal load of buildings. This is achieved by reflecting the infrared portion of the solar spectrum through a phase transition in the monoclinic M-phase (M) of VO 2 induced by heating. In this study, a scalable continuous flow synthesis process invented by Argonne was employed to explore a wide parameter space, targeting the controlled synthesis of monoclinic VO 2 (M) nanoparticles with well-controlled sizes and morphologies. Additionally, a doping strategy and surface modifications were utilized for high-throughput tuning of the metal-to-insulator transition temperature. Strategies to enhance the solar modulation properties of VO 2 nanoparticles in polymer films were investigated through (i) morphological transformation from spherical to nanorod structures, (ii) surface modification with low refractive index ligands, and (iii) incorporation of additional thermochromic materials for improved solar energy modulation and aesthetically appealing colors in smart films. Furthermore, the study outlines scaling-up synthesis methods for VO 2 nanoparticles in a continuous flow reactor using hydrazine monohydrate. This comprehensive investigation provides valuable insights into the upscaling synthesis and design of advanced VO 2 /polymer composite smart window films with enhanced functionality, solar energy modulation and visible light transmittance, driving the technology a step close for industrial application.

14 SOLAR ENERGY↗

Shape-Selective Mesoscale Nanoarchitectures: Preparation and Photocatalytic Performance

We create ordered arrays of shape-selective gold-titania composite nanomaterials at the mesoscale (100 µm to 5 mm) by a combination of both bottom-up and top-down approaches for exquisite control of the size, shape, and arrangement of nanomaterials. Lithographic techniques along with wet chemical synthetic methods were combined to create these composite nanomaterials. The photocatalytic activity of these TiO 2, TiO 2 -Au and SiO 2 -TiO 2 -Au nano-composite mesoscale materials was monitored by the photodegradation of a model analyte, methyl orange, under UV and visible (Vis) illumination. Bare TiO 2 - and SiO 2 -TiO 2 -coated pillar arrays showed significant activity toward methyl orange in UV light with degradation rates on the order of 10 −4 –10 −3 min −1 . The photocatalytic activity of these arrays was also found to depend on the nanoparticle shape, in which particles with more edges and corners were found to be more reactive than spherical particles (i.e., the photocatalytic activity decreased as follows: diamonds > squares > triangles > spheres). SiO 2 -TiO 2 -Au nano-composite pillar arrays were tested in both UV and Vis light and showed increased activity in Vis light but decreased activity in UV light as compared to the bare semiconductor arrays. Additionally, the Au nanorod-functionalized nanoarrays exhibit a strong shape-dependence in their photocatalytic activity toward methyl orange degradation in Vis light.

36 MATERIALS SCIENCE↗

A Molten Salt Electrochemical Process for the Preparation of Cost-Effective p-Block (Coating) Materials

Solar energy applications rely heavily on p-block elements and transition metals. Silicon is, by far, the most commonly used material in photovoltaic cells and accounts for about 85% of modules sold presently. Of late, thin film photovoltaic cells have gained momentum because of their higher efficiencies. Most of these thin film devices are made out of just five elements, namely, cadmium, tellurium, selenium, indium, gallium and copper. The present manuscript describes an elegant and inexpensive molten salt-based electrolytic process for fabricating a tellurium-coated metallic substrate. A three-electrode set up was employed to coat iridium with tellurium from a molten bath containing lithium chloride, lithium oxide and tellurium tetrachloride (LiCl-Li 2 O-TeCl 4 ) at 650 °C for a duration ranging from 30 to 120 min under a galvanostatic mode. The tellurium coating was observed to be thick, uniform, smooth and homogeneous. Additionally, the deposited tellurium did not chemically react with the iridium substrate to form intermetallic compounds, which is a good feature from the standpoint of the device’s performance characteristics. The present process, being generic in nature, shows the potential for the manufacture of both the coated substates and high-purity elements not just for tellurium but also for other p-block elements.

36 MATERIALS SCIENCE↗

Preparation of Highly Crystalline Silk Nanofibrils and Their Use in the Improvement of the Mechanical Properties of Silk Films

Due to their commendable biocompatibility, regenerated silk fibroin (RSF) films have attracted considerable research interest. However, the poor mechanical properties of RSF films have limited their use in various biomedical applications. In this study, a novel, highly crystalline silk fibril was successfully extracted from silk by combining degumming with ultrasonication. Ultrasonication accelerated the development of silk nanofibrils measuring 130–200 nm on the surface of the over-degummed silk fibers, which was confirmed via scanning electron microscopy. Additionally, the crystallinity index of silk fibril was found to be significantly higher (~68%) than that of conventionally degummed silk (~54%), as confirmed by the Fourier-transform infrared (FTIR) spectroscopy results. Furthermore, the breaking strength and elongation of the RSF film were increased 1.6 fold and 3.4 fold, respectively, following the addition of 15% silk nanofibrils. Thus, the mechanical properties of the RSF film were remarkably improved by the addition of the silk nanofibrils, implying that it can be used as an excellent reinforcing material for RSF films.

36 MATERIALS SCIENCE↗

Preparation of SBA-15-Supported Metals by Vapor-Phase Infiltration

A simple method is presented for incorporating various catalytic metals into the pores of SBA-15 using vapor-phase infiltration. The precursors used in Atomic Layer Deposition (ALD) for Pt, Pd, Rh, Ru, and Ni were exposed to an evacuated SBA-15, resulting in monolayer films of the adsorbed precursors inside the mesopores. The metal particles that formed after removal of the precursor ligands remained in the pores and had particle sizes ranging from 3.8 nm for Pt to 5.2 nm for Ni, as determined by Transmission Electron Microscopy (TEM), XRD, and CO chemisorption. Metal loadings for saturation exposures ranged from 5.1-wt% for Ni to 9.1-wt% for Pt; however, uniform deposition was demonstrated for lower loadings of Pd by decreasing the amount of precursor. To determine the effect of the surface composition of the mesopores, Pd particles were also added to SBA-15 that was coated with a 0.2-nm film of ZrO2.

Rh↗

Preparation of Smart Materials by Additive Manufacturing Technologies: A Review

Over the last few decades, advanced manufacturing and additive printing technologies have made incredible inroads into the fields of engineering, transportation, and healthcare. Among additive manufacturing technologies, 3D printing is gradually emerging as a powerful technique owing to a combination of attractive features, such as fast prototyping, fabrication of complex designs/structures, minimization of waste generation, and easy mass customization. Of late, 4D printing has also been initiated, which is the sophisticated version of the 3D printing. It has an extra advantageous feature: retaining shape memory and being able to provide instructions to the printed parts on how to move or adapt under some environmental conditions, such as, water, wind, light, temperature, or other environmental stimuli. This advanced printing utilizes the response of smart manufactured materials, which offer the capability of changing shapes postproduction over application of any forms of energy. The potential application of 4D printing in the biomedical field is huge. Here, the technology could be applied to tissue engineering, medicine, and configuration of smart biomedical devices. Various characteristics of next generation additive printings, namely 3D and 4D printings, and their use in enhancing the manufacturing domain, their development, and some of the applications have been discussed. Special materials with piezoelectric properties and shape-changing characteristics have also been discussed in comparison with conventional material options for additive printing.

36 MATERIALS SCIENCE↗