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At least 181 records · Page 10

Construct design for CRISPR/Cas-based genome editing in plants

CRISPR construct design is a key step in the practice of genome editing, which includes identification of appropriate Cas proteins, design and selection of guide RNAs (gRNAs), and selection of regulatory elements to express gRNAs and Cas proteins. Here, we review the choices of CRISPR-based genome editors suited for different needs in plant genome editing applications. We consider the technical aspects of gRNA design and the associated computational tools. We also discuss strategies for the design of multiplex CRISPR constructs for high-throughput manipulation of complex biological processes or polygenic traits. We provide recommendations for different elements of CRISPR constructs and discuss the remaining challenges of CRISPR construct optimization in plant genome editing.

59 BASIC BIOLOGICAL SCIENCES↗

Constructing nested coordinates inside strongly shaped toroids using an action principle

A new approach for constructing polar-like boundary-conforming coordinates inside a toroid with strongly shaped cross-sections is presented. A coordinate mapping is obtained through a variational approach, which involves identifying extremal points of a proposed action in the mapping space from [0,2π] 2 ×[0,1] to a toroidal domain in $\mathbb{R}$ 3 . This approach employs an action built on the squared Jacobian and radial length. Extensive testing is conducted on general toroidal boundaries using a global Fourier–Zernike basis via action minimisation. The results demonstrate successful coordinate construction capable of accurately describing strongly shaped toroidal domains. The coordinate construction is successfully applied to the computation of three-dimensional magnetohydrodynamic equilibria in the GVEC code where the use of traditional coordinate construction by interpolation from the boundary failed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Lung cancer mortality among construction workers: implications for early detection

Objectives This study examined predictors of lung cancer mortality, beyond age and smoking, among construction workers employed at US Department of Energy (DOE) sites to better define eligibility for low-dose CT (LDCT) lung cancer screening. Methods Predictive models were based on 17 069 workers and 352 lung cancer deaths. Risk factors included age, gender, race/ethnicity, cigarette smoking, years of trade or DOE work, body mass index (BMI), chest X-ray results, spirometry results, respiratory symptoms, beryllium sensitisation and personal history of cancer. Competing risk Cox models were used to obtain HRs and to predict 5-year risks. Results Factors beyond age and smoking included in the final predictive model were chest X-ray changes, abnormal lung function, chronic obstructive pulmonary disease (COPD), respiratory symptoms, BMI, personal history of cancer and having worked 5 or more years at a DOE site or in construction. Risk-based LDCT eligibility demonstrated improved sensitivity, specificity and positive predictive value compared with current US Preventive Services Task Force guidelines. The risk of lung cancer death from 5 years of work in the construction industry or at a DOE site was comparable with the risk from a personal cancer history, a family history of cancer or a diagnosis of COPD. LDCT eligibility criteria used for DOE construction workers, which includes factors beyond age and smoking, identified 86% of participants who eventually would die from lung cancer compared with 51% based on age and smoking alone. Conclusions Results support inclusion of risk from occupational exposures and non-malignant respiratory clinical findings in LDCT clinical guidelines.

Public, Environmental & Occupational Health↗

Appendix F New Construction and Replacement of Existing Facilities at Sandia National Laboratories New Mexico

A number of construction and demolition projects are planned for the 10-year period evaluated in this Sandia National Laboratories, New Mexico (SNL/NM) site-wide environmental impact statement (SWEIS). Construction and decommissioning and demolition (D&D) activities are continually being accomplished at SNL/NM as new facilities are brought on line to replace older, less efficient facilities. The construction and D&D projects presented in this appendix are projected to take place, assuming funding and administrative/regulatory approvals are obtained, under both the No Action Alternative and the Expanded Operations Alternative. Under the Reduced Operations Alternative, no new construction projects were assumed to take place, and D&D activities were assumed to be limited to those needed to maintain a safe operating environment on the site.

42 ENGINEERING↗

LLNS Request for Variance From 10 CFR 851 for Construction of LLNL Emergency Operations Center

Lawrence Livermore National Security, LLC (LLNS) is submitting the following variance application requesting the use of the State of California’s Occupational Safety and Health Administration (Cal/OSHA) Regulations in lieu of Title 10 Code of Federal Regulations Part 851 (10 CFR 851, the Rule), Worker Safety and Health Program, Subpart B (Program Requirements), Subpart C (Specific Program Requirements), and Appendix A (Worker Safety and Health Functional Areas), solely with respect to the construction of the new Lawrence Livermore National Laboratory (LLNL) Emergency Operations Center (EOC) facility. The request is in support of the National Nuclear Security Administration (NNSA) “pilot” to streamline the delivery of commercial-like line item construction projects under $50 million. This pilot is aligned with the approved NA-50 safety approach for the projects in the pilot. This pilot is to test and demonstrate innovation leading to a reduced cost of construction for building commercial type structures at Department of Energy (DOE)/NNSA facilities. The variance proposes to permit local/regional construction businesses contracted to Management & Operation contractor operated facilities to bid, operate, execute, and comply with safety and health standards they utilize in their business outside of the DOE Complex. This will permit compliance to standards that are as safe and healthful as those in 10 CFR 851 without confusion, additional cost, and inefficiencies associated with the burden of compliance to an unfamiliar regulatory spectrum.

99 GENERAL AND MISCELLANEOUS↗

Data Quality Objectives Supporting Radiological Air Emissions Monitoring for the PNNL-Richland Campus: North Campus Construction (Rev. 3)

Starting in fiscal year 2023, the north area of the PNNL-Richland Campus will undergo development. Initially, infrastructure (water, electrical) improvements will be installed. Later development includes the construction of several new office buildings. The area to be developed currently contains no buildings but does have two existing solar-powered ambient air sampling stations. Under the requirements of Washington State Department of Health Radioactive Air Emissions License -005, the PNNL-Richland Campus must operate and maintain a radiological air monitoring program. This revision documents and evaluates how the new North Campus construction impacts ambient air surveillance stations within the development region. This revision also considers current stack configurations and uses an updated environmental dispersion model and updated meteorological data. The DQO team concluded that one sampling station in the construction area will be relocated and the other remain in place. The evaluations conducted for this DQO also identified a third sampling station outside the development area that is recommended for relocation as a result of updated dispersion modeling. Recommended sites for the relocations are presented. Considerations for sampling in and around a construction zone are also addressed. Additionally, programmatic improvements to the ambient air sampling program were identified in the DQO process.

54 ENVIRONMENTAL SCIENCES↗

Improved digital construction binder solution utilizing calcium aluminate additive for Infrastructure Scale Additive Manufacturing

Oak Ridge National Laboratory (ORNL) worked with Kerneos Inc., a Division of Imerys USA, Inc. to develop an improved digital construction binder using calcium aluminate additives produced by Kerneos along with locally available concrete materials. When the two-stage (2K) binder formulation was added to commercially available Portland Limestone Cement and sand to form a digital construction mortar, its strength exceeded a number of commercially available digital construction binders both at early and later ages. At the same time, the developed formulation showed precise control of setting time after addition and showed very low shrinkage making it a strong, reliable, and easily customizable alternative to fixed proprietary digital construction binders.

36 MATERIALS SCIENCE↗

Light, High Performance and Scalable Coal-Derived Composites for Construction: Precast and Cast-in-Place Applications

The overall objective of this project was to produce a coal-based construction material that has up to ~95 weight percent (wt. %) coal with physical, chemical, and thermal properties exceeding those of ordinary Portland cement (OPC)-based construction materials. Additionally, the project aimed to minimize external binders by implementing novel mixing techniques, while exceeding the performance/cost ratio of OPC. Finally, the project was to demonstrate production of precast products via the design and fabrication of products via a bench scale process. Consistent with some of these objectives, the project successfully fabricated samples of coal-based composite materials with >80 wt% coal with physical, chemical and thermal properties on par with cement-based concrete. Select samples demonstrated compressive strengths with >7,000 psi and flexural strength of >420 psi. The composite materials minimized external binders and also demonstrated durability, as evidenced by resistance to acidic and basic solutions. Finally, larger slab and beam type samples were produced using a process developed by the Recipient, although, the process was not semicontinuous in nature. Taken together, the results of this project suggest that domestic coal has potential to serve as a replacement for cementitious materials utilized in incumbent construction technologies, which could significantly reduce the energy and emissions of the construction industry

01 COAL, LIGNITE, AND PEAT↗

Orbital construction demonstration study. Volume 1: Executive summary

A conceptual design and program plan for an Orbital Construction Demonstration Article (OCDA), that can be used for technology growth and verification, and as the construction facility for a variety of large structures is presented. The OCDA design includes a large work platform, a rotating manipulator boom, a 250 kw solar array, and a core module of subsystems with a total mass of 37,093 kg, that can be assembled in three shuttle flights. An analysis of OCDA continued utility potential indicates that a shuttle tended platform with 250 kW of power can effectively be used to construct highly beneficial antenna systems and large demonstration articles that advance solar power satellite technologies. The construction of 100 m parabolic reflectors for use as a radiometer for measuring soil moisture and water salinity was found to be within the capabilities of OCDA concept. With 252 fixed beams for high population centers, and 16 scanning beams for rural areas, the antenna has the potential to significantly improve U.S. space based communications systems. The OCDA, that is slightly increased in size, was found adequate to build a large 2 MW solar array which, when coupled to a transmit antenna, demonstrate power transfer from space to ground.

Source record↗

Space construction base support requirements for environmental control and life support systems

A Space Station analysis study is being performed for NASA which identifies cost-effective Space Station options that can provide a space facility capable of performing space construction, space manufacturing, cosmological research, earth services, and other functions. A space construction base concept for the construction of large structures, such as those needed to implement satellite solar power for earth usage, will be used as a basis for discussing requirements that impact the design selection, level of integration, and operation of environmental control and life support systems (ECLSS). The space construction base configuration also provides a basic Space Station facility that can accommodate biological manufacturing modules, ultrapure glasses manufacturing modules, and modules for other services in a building-block fashion. Examples of special problems that could dictate hardware required to augment the basic ECLSS for autonomous modules will be highlighted. Additionally, overall intravehicular (IVA) and extravehicular (EVA) activities and requirements that could impact the basic station ECLSS degree of closure are discussed.

Thiele, R. J.↗

Space power stations - Space construction, transportation, and pre-development, space project requirements

Several features of solar energy space power stations are discussed. An end-to-end analysis of a system using silicon solar cells is reviewed, and the merits of construction in low earth orbit and in geosynchronous orbit are compared. A suggested space construction procedure, described in detail, would use a 'beam builder', an automated machine, to fabricate the first sublevel truss structural members from strip stock material that is stored on reels. An assembly jig would then be used to position a number of beam builders in the proper location and to support the beams as they are produced to facilitate joining them to form the final space power station structure. Space projects for evaluating the construction concept are proposed, and a possible space construction sequence is considered. Space transportation that would be required in conjunction with the space power station is described.

Piland, R.↗

Space construction system analysis. Part 2: Platform definition

The top level system requirements are summarized and the accompanying conceptual design for an engineering and technology verification platform (ETVP) system is presented. An encompassing statement of the system objectives which drive the system requirements is presented and the major mission and subsystem requirements are described with emphasis on the advanced communications technology mission payload. The platform design is defined and used as a reference configuration for an end to space construction analyses. The preferred construction methods and processes, the important interactions between the platform design and the construction system design and operation, and the technology development efforts required to support the design and space construction of the ETVP are outlined.

Hart, R. J.↗

Space construction technology needs

Space construction systems made feasible by an operational Space Shuttle are discussed with a view toward assembly, installation and construction support equipment. The level of construction capability will be reflected in the number of launches to accomplish a certain mission, either in terms of the mission time line or on the density of packaging in the Orbiter payload bay. It is noted that the development of construction support equipment in zero-gravity simulations should be the most productive initial activity. Crew EVAs, as well as the beam builder, cherrypicker and power distribution buses are covered in detail.

Jenkins, L. M.↗

SPS construction perspective. Summary

Projections concerning the general construction requirements for a solar power satellite (SPS) are summarized. It is recognized that the ability to construct an SPS must be developed through an evolutionary process. This process would begin with shuttle operations and when construction timelines exceed the shuttle capability, small manned bases in low Earth orbit (LEO) would be used. The influence of construction methods on design, assembly bases, and crew considerations are addressed.

Benson, H.↗

Cost containment and KSC Shuttle facilities or cost containment and aerospace construction

This presentation has the objective to show examples of Cost Containment of Aerospace Construction at Kennedy Space Center (KSC), taking into account four major levels of Project Development of the Space Shuttle Facilities. The levels are related to conceptual criteria and site selection, the design of construction and ground support equipment, the construction of facilities and ground support equipment (GSE), and operation and maintenance. Examples of cost containment are discussed. The continued reduction of processing time from landing to launching represents a demonstration of the success of the cost containment methods. Attention is given to the factors which led to the selection of KSC, the use of Cost Engineering, the employment of the Construction Management Concept, and the use of Computer Aided Design/Drafting.

Brown, J. A.↗

On the construction of the Voronoi mesh on a sphere

The primary feature of the novel construction of the Voronoi (1908) mesh presented is the algorithm's adding of points one-at-a-time, until the final mesh is achieved. The addition of one point to an existing Voronoi mesh of K points means that only local changes are needed to construct a mesh of K + 1 points; this construction is especially suited to time-dependent problems in virtue of the ability to reduce the construction to O(N) operations when configurations are close, while the algorithm does not break down in cases of configurations that are far apart. Illustrative numerical experiments substantiate the O(N) operation count for a typical case.

Augenbaum, J. M.↗

Processes in construction of failure management expert systems from device design information

This paper analyzes the tasks and problem solving methods used by an engineer in constructing a failure management expert system from design information about the device to te diagnosed. An expert test engineer developed a trouble-shooting expert system based on device design information and experience with similar devices, rather than on specific expert knowledge gained from operating the device or troubleshooting its failures. The construction of the expert system was intensively observed and analyzed. This paper characterizes the knowledge, tasks, methods, and design decisions involved in constructing this type of expert system, and makes recommendations concerning tools for aiding and automating construction of such systems.

Malin, Jane T.↗

EVA space construction - Experience and fundamental issues

Results are presented from EVA space construction studies performed in 1 g, simulated 0 g, and on-orbit. The studies include tests of astronaut participation on the Mobile Work Station concept and the Swing-Arm Beam Erector. Also, results from the Experimental Assembly of Structures in EVA and the Assembly Concept for Construction of Erectable Space Structure programs are summarized. EVA construction applications for the Space Station are discussed and construction scenarios are developed.

Heard, Walter L., Jr.↗