Techniques

• Photolithography - Using light to produce patterns in chemicals, and then etching to expose the surface.
• Electron beam lithography - Similar to photolithography, but using electron beams instead of light.
• Scanning tunneling microscope (STM) - Can be used to both image, and to manipulate structures as small as a single atom.
• Molecular self-assembly - Arbitrary sequences of DNA can now be synthesized cheaply in bulk, and used to create custom proteins or regular patterns of amino acids. Similarly, DNA strands can bind to other DNA strands, allowing simple structures to be created.

Predicting Z-DNA structure

It is possible to predict the likelihood of a DNA sequence forming a Z-DNA structure. An algorithm for predicting the propensity of DNA to flip from the B-form to the Z-form, ZHunt, was written by Dr. P. Shing Ho in 1984 (at MIT). This algorithm was later developed by Tracy Camp, P. Christoph Champ, Sandor Maurice, and Jeffrey M. Vargason for genome-wide mapping of Z-DNA (with P. Shing Ho as the principal investigator).^[3] Z-Hunt is available at Z-Hunt online.

History

Z-DNA was the first crystal structure of a DNA molecule to be solved (see: x-ray crystallography). It was solved by Alexander Rich and co-workers in 1979 at MIT.^[1] The crystallisation of a B- to Z-DNA junction in 2005^[2] provided a better understanding of the potential role Z-DNA plays in cells. Whenever a segment of Z-DNA forms, there must be B-Z junctions at its two ends, interfacing it to the B-form of DNA found in the rest of the genome.

:)) some funny pictures with women ...

wow this girl is nice

References

GREEK IONIAN BLUEGREEN WATER part2. the amazing beach from more close look we approching it! creative commons non commecrial-share alike

Health and environmental issues

There is a growing body of scientific evidence which demonstrates the potential for some nanomaterials to be toxic to humans or the environment [3], [4], [5]. The smaller a particle, the greater its surface area to volume ratio and the higher its chemical reactivity and biological activity. The greater chemical reactivity of nanomaterials results in increased production of reactive oxygen species (ROS), including free radicals [6]. ROS production has been found in a diverse range of nanomaterials including carbon fullerenes, carbon nanotubes and nanoparticle metal oxides. ROS and free radical production is one of the primary mechanisms of nanoparticle toxicity; it may result in oxidative stress, inflammation, and consequent damage to proteins, membranes and DNA [7].

The extremely small size of nanomaterials also means that they are much more readily taken up by the human body than larger sized particles. Nanomaterials are able to cross biological membranes and access cells, tissues and organs that larger-sized particles normally cannot [8]. Nanomaterials can gain access to the blood stream following inhalation [9] or ingestion [10]. At least some nanomaterials can penetrate the skin [11]; even larger microparticles may penetrate skin when it is flexed [12]. Broken skin is an ineffective particle barrier [13], suggesting that acne, eczema, shaving wounds or severe sunburn may enable skin uptake of nanomaterials more readily. Once in the blood stream, nanomaterials can be transported around the body and are taken up by organs and tissues including the brain, heart, liver, kidneys, spleen, bone marrow and nervous system [14]. Nanomaterials have proved toxic to human tissue and cell cultures, resulting in increased oxidative stress, inflammatory cytokine production and cell death [15]. Unlike larger particles, nanomaterials may be taken up by cell mitochondria [16] and the cell nucleus [17], [18]. Studies demonstrate the potential for nanomaterials to cause DNA mutation [19] and induce major structural damage to mitochondria, even resulting in cell death [20], [21].

Size is therefore a key factor in determining the potential toxicity of a particle. However it is not the only important factor. Other properties of nanomaterials that influence toxicity include: chemical composition, shape, surface structure, surface charge, aggregation and solubility [22], and the presence or absence of functional groups of other chemicals [23]. The large number of variables influencing toxicity means that it is difficult to generalise about health risks associated with exposure to nanomaterials – each new nanomaterial must be assessed individually and all material properties must be taken into account.

In its seminal 2004 report Nanoscience and Nanotechnologies: Opportunities and Uncertainties, the United Kingdom's Royal Society recommended that nanomaterials be regulated as new chemicals, that research laboratories and factories treat nanomaterials "as if they were hazardous", that release of nanomaterials into the environment be avoided as far as possible, and that products containing nanomaterials be subject to new safety testing requirements prior to their commercial release. Yet regulations world-wide still fail to distinguish between materials in their nanoscale and bulk form. This means that nanomaterials remain effectively unregulated; there is no regulatory requirement for nanomaterials to face new health and safety testing or environmental impact assessment prior to their use in commercial products, if these materials have already been approved in bulk form.

The health risks of nanomaterials are of particular concern for workers who may face occupational exposure to nanomaterials at higher levels, and on a more routine basis, than the general public.

bubble cave in bodrum

This is a time lapsed vid from my 21st floor window of the morning traffic. 2 and 1/2 hours in 2 and 1/2 minutes.

Specifically, it was a race between two teams of young scientists working in Britain, as well as the esteemed chemist Linus Pauling, based in California. Already a Nobel laureate, Pauling may have been the favorite, but the discovery would ultimately be made by his British counterparts. Rosalind Franklin and Maurice Wilkins were trying to identify the structure by studying X-ray diffractions of the DNA molecule. But Jim Watson and Francis Crick studied a little bit of everything -- including, to the consternation of some, the work of their competitors. A few have gone so far as to accuse Watson of stealing Franklin's X-ray work. In any case, Waston and Crick's inquisitive working style ultimately allowed them to determine the DNA structure first, in 1953 -- an achievement that led to their Nobel Prize in 1962. Meanwhile, Franklin passed away in 1958 from cancer. Produced/directed by David Glover and edited by Joe Bini. Learn More the science that led to DNA in the Special Report. Photos: Maurice Wilkins (top), who worked with Rosalind Franklin, searching for the DNA structure by means of X-ray crystallography. Examples of Rosalind Franklin's X-rays (bottom left). Linus Pauling (bottom right), who was also searching for the DNA structure.

Make ice cream quick and easy using a zip-top bag

Taken in the national museum in Rome, Itay. The sphere appears to provide a reflection of the surrounding court yard and the sky. But when you take a closer look... it seems otherwise....