Scanning electron micrograph of a cross section of the finished device. An array of densely spaced nanopillars constitutes the entropically unfavorable region. The pillar spacing was 135 nm and their width approximately 80 nm. Copyright © Cornell
Fluorescing DNA molecules show the separation of two different lengths of DNA. In the first image, DNA molecules pulled by a weak electric field gather at the edge of a sieve made of tiny pillars. After a stronger field pulse of two seconds, the shorter molecules were fully inserted, while the longer molecules remained partially in the open, entropically favorable region. When the field was removed, the longer molecules extracted themselves from the pillar region, as shown at right. Copyright © Cornell University
Cornell University researchers have demonstrated a novel method of separating DNA molecules by length. The technique might eventually be used to create chips or other microscopic devices to automate and speed up gene sequencing and DNA fingerprinting.
The method, which uses a previously discovered entropic recoil force, has better resolution -- that is, better ability to distinguish different lengths -- than others tried so far, the researchers say. They separated DNA strands of two different lengths, using their own nanofabricated device, and demonstrated that modifications would make it possible to separate strands of many different lengths.
A description of the experiment is scheduled to be published in the Oct. 1, 2002, issue of the journal Analytical Chemistry by graduate student Mario Cabodi, postdoctoral researcher Stephen Turner and Harold Craighead, the C.W. Lake Jr. Professor of Productivity.
Bill Steele | Cornell News
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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