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Home > Electron Microscopes News > Scripps Research Scientists Shed Light on How DNA Is Unwound So That Its Code Can Be Read

Scripps Research Scientists Shed Light on How DNA Is Unwound So That Its Code Can Be Read




Researchers at The Scripps Research Institute have figured out how a macromolecular machine is able to unwind the long and twisted tangles of DNA within a cell's nucleus so that genetic information can be "read" and used to direct the synthesis of proteins, which have many specific functions in the body. (2008-11-25)


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Materials science: Deformation of the ultra-strong - Nature.com (subscription)

Materials science: Deformation of the ultra-strong
Nature.com (subscription), UK - 15 hours ago
In situ electron microscopy observations of the extrusion of single nanocrystals from graphitic cages show that these crystals deform near their theoretical ...
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Quantum Size Effects on Dielectric Constants and Optical Absorption of Ultrathin Silicon Films
The size dependence of the dielectric constants and optical absorption for silicon nanostructured films are investigated using density-functional theory. A critical thickness of 4.3 nm is observed for Si (100)-oriented thin films. Within this critical thickness, the dielectric function and optical absorption show remarkable size dependence, and a large reduction of static dielectric constant (from 10.8 to 4.4) is observed. This is in contrast to the weak dependence of dielectric constant on film thickness in silicon dioxide thin films. The pronounced dependence and large critical thickness demonstrate a quantum-confinement effect on optical properties, which is of great importance to nanophotonics.
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Falls Church can be a hip place

Even though it's always dangerous for me to go out alone under any circumstance, I sometimes am able to leave my electronic cloister and take a walk downtown on a particularly beautiful sunny Saturday afternoon, as I did yesterday. I need to do more physical activity for my health, so I took the risk. I was able to walk about a half a mile, which is at least something. One of my destinations was, naturally, a coffee house.

Stacy's Coffee Parlor has been around for a few years now. It's in a somewhat rundown shopping area which has not yet experienced the axe of "renewal," though new construction is going on all around it. Unlike the big corporate coffee giant, Stacy's is unique and independent, and it is like a bit of college town atmosphere in this otherwise businesslike suburb. This Saturday it was mostly empty, except for a group of science fiction and fantasy fans who were meeting there for entertaining conversation about weird science.

As a sketch artist, I need to keep up my sophisticated status. And sketch artists who are in the cool zone have Moleskine sketchbooks. They are prohibitively expensive, which is why I hadn't gotten one before now. But I was able to get one on sale so it was now in my backpack. But it was also sketch-free and unused. I was too nervous to draw in it. What if I did a wretched drawing on one of these precious pages? Especially the first drawing! My Moleskine drawings have to be super-good to justify my use of such a status symbol.

Since coffee houses are familiar territory, I decided to do a coffee house drawing on the first page of the Moleskine. This took me about an hour, while I sipped coffee or water and heard bits and pieces of the conversation. The drawing, thank goodness, looked all right, and my perspective was pretty good. And then after a while the science fiction fans discovered me and my drawing. They were impressed by it and even more, they wanted copies, which they were willing to pay for! I made a deal and they will get 15 copies for them to give each other as presents. So my Moleskine has an auspicious beginning.

Pen and marker drawing on Moleskine. The yellow color is the "natural" color of the sketchbook page.

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Differential Near-Field Scanning Optical Microscopy Using Sensor Arrays
In this paper, we introduce a new aperture-type near-field scanning optical microscopy (NSOM) imaging concept that relies on specially designed large-area (e.g., $≫200$ nm $,times,$200 nm) aperture geometries having sharp corners. Unlike in conventional NSOM, the spatial resolution of this near-field imaging modality is not determined by the size of the aperture, but rather by the sharpness of the corners of the large aperture. This approach significantly improves the light throughput of the near-field probe and, hence, increases the SNR. Here, we discuss the basic concepts of this near-field microscopy approach and illustrate both theoretically and experimentally how an array of detectors can be utilized to further improve the SNR of the near-field image. The results of this work are particularly relevant for imaging of biological samples at a spatial resolution of $≪ 50$ nm with significantly improved image quality.
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Electron-microscopic observation of mouse spleen tissue infected with Orientia tsutsugamushi isolated from Shandong, China

Low-virulent Orientia tsutsugamushi (Ot) were successfully isolated from scrub typhus patients in Shandong, China, and the isolates were similar to the Kawasaki type identified by nested polymerase chain reaction (PCR). To identify the morphological characterization of the low-virulent Ot, and elucidate the pathological changes on host cells, mouse spleen tissue infected with the Ot isolated from Shandong was used for the ultrastructural study. Transmission electron microscopy showed that the Ot parasitized in the spleen were different in size, shape and electron density and many significant changes occurred in cytoplasmic organelles of the inoculated mouse spleen cells. Swollen perinuclear cisterna was observed in the nuclear membranes of mononuclear cells and a multivesicular body was found in the intracytoplasm of the macrophage. In the phagosome of the macrophage, many Ot enveloped with an additional membrane were found to push the phagosomal membrane outward from inside. The results indicated that the low-virulent Ot and the spleen cells suffered various damages.

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