Grid Meridian
Grid Meridian - Related Videos
01:28
Meridians
0 Views •
2025
In surveying, meridians are vital reference lines to measure directions and establish accurate land orientations. Meridians run from the north to the south poles, providing a stable framework for angular measurements and mapping. Meridians are fundamental in survey design, with the primary types being astronomic, magnetic, and assumed meridians. Each type offers distinct benefits and limitations, selected based on the project's scale and precision needs.The astronomic meridian is aligned with...
08:01
Visualizing Proteins and Macromolecular Complexes by Negative Stain EM: from Grid Preparation to Image Acquisition
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Cited by 137 •
2011
Visualizing protein samples by negative stain electron microscopy (EM) has become a popular structural analysis method. It is useful for quantitative structural analysis, such as calculating a 3D reconstruction of the molecules being studied, and also for qualitative examination of the quality of protein preparations. In this article we present detailed protocols for preparing the EM grids, staining the sample and visualizing the sample in an electron microscope. Novice users can follow these...
05:05
Preparation of High-Temperature Sample Grids for Cryo-EM
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Cited by 5 •
2021
This paper provides a detailed protocol for preparing sample grids at temperatures as high as 70 °C, prior to plunge freezing for cryo-EM experiments.
06:53
Fabrication of Monolayer Graphene-Coated Grids for Cryoelectron Microscopy
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Cited by 7 •
2023
Here, we describe a protocol for applying a single monolayer of graphene to electron microscopy grids and how to prepare them for use in cryoEM structure determination.
03:50
Capsule-Based Negative Staining of Virus Samples on TEM Grids: A Heavy Metal Staining Technique to Visualize the Ultrastructure of Enveloped Viruses
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2025
In this video, we demonstrate the negative staining of enveloped virus samples using a processing capsule within the biocontainment environment. The negatively stained viruses can be visualized using transmission electron microscopy to investigate viral structure and morphology with nanometer resolution.
FAQs
Meridian convergence makes the angle between grid north and true north change from one location to another within a projected area. Consequently, a bearing measured relative to the grid meridian may not equal a bearing referenced to true north. Engineers account for this local angular difference when converting directions or comparing survey observations with map-based bearings.
The central meridian supplies the principal north-south reference for many projected coordinate systems. Grid north follows the projection’s northing direction, commonly aligned with this meridian, so bearings and angles can be expressed consistently within the coordinate framework. Because the relationship to true north changes away from the reference, the chosen projection and location remain important.
Grid-based and geographic direction references serve different calculation contexts. Grid bearings use the northing direction of the projected coordinate system, whereas true-north bearings use the geographic meridian at a location. Their difference is not necessarily constant across a map, since meridian convergence varies spatially. Mixing the two without conversion can compromise directional consistency.
A practical workflow begins by identifying the projected coordinate system used for the engineering map. The engineer then uses its grid north or central-meridian relationship to establish the working direction, converts geographic and grid coordinates as needed, and computes bearings or angles in one consistent reference. This sequence supports reproducible survey and layout calculations.
For route alignment, the grid meridian provides a common directional reference for relating field measurements to mapped positions. In construction layout, the same reference helps transfer bearings and coordinate-based locations from project plans to the work area. Its value is greatest when multiple measurements, drawings, or layout operations must remain spatially consistent.
Engineers should check where a direction was referenced before using it in a calculation or comparing it with another plan. A grid bearing, a true-north bearing, and a direction derived from geographic coordinates may require transformation into a common reference. Recording the projection and accounting for local convergence helps preserve reliable angles, bearings, and positions.