Why are blue light-emitting diodes so bright?

Nature Research Journals Press Release. Other newsworthy papers include Molecules as ID tags - Nature Materials; Excess Wnt kills - Nature Immunology


For papers that will be published online on 03 September 2006

This press release is copyrighted to the Nature journals mentioned below.

This press release contains:

· Summaries of newsworthy papers:

- Why are blue light-emitting diodes so bright? - Nature Materials

- Molecules as ID tags - Nature Materials

- Excess Wnt kills - Nature Immunology

· Mention of papers to be published at the same time with the same embargo

· Geographical listing of authors

PDFs of all the papers mentioned on this release can be found in the relevant journal's section of http://press.nature.com. Press contacts for the Nature journals are listed at the end of this release.

Warning: This document, and the Nature journal papers to which it refers, may contain information that is price sensitive (as legally defined, for example, in the UK Criminal Justice Act 1993 Part V) with respect to publicly quoted companies. Anyone dealing in securities using information contained in this document, or in advance copies of a Nature journal's content, may be guilty of insider trading under the US Securities Exchange Act of 1934.

PICTURES: To obtain artwork from any of the journals, you must first obtain permission from the copyright holder (if named) or author of the research paper in question (if not).

HYPE: We take great care not to hype the papers mentioned on our press releases, but are sometimes accused of doing so. If you ever consider that a story has been hyped, please do not hesitate to contact us at [email protected], citing the specific example.

NOTE: Once a paper is published, the digital object identifier (DOI) number can be used to retrieve the abstract and full text from the journal web site (abstracts are available to everyone, full text is available only to subscribers). To do this, add the DOI to the following URL: http://dx.doi.org/ (For example, http://dx.doi.org/10.1038/ng730). For more information about DOIs and Advance Online Publication, see http://www.nature.com/ng/aop/.


************************************ NATURE MATERIALS *****************************

[1] Why are blue light-emitting diodes so bright?

DOI: 10.1038/nmat1726

In the October issue of Nature Materials, a team of researchers propose a solution to the puzzle of why blue light-emitting diodes (LEDs) are so bright. Despite their huge commercial success, until now the reason for this unusual brightness has not been known. The material they are made from, indium gallium nitride, can only be fabricated to such a poor quality that it would not normally be expected to emit much light.

Shigefusa Chichibu and colleagues have ingeniously used positron annihilation spectroscopy to show that the blue light emission originates from structures that consist of only a few atoms, which is what made them so difficult to observe in experiments. The authors propose that their results agree with an older model of structures formed from just three indium atoms in a chain, alternating with nitrogen, that is, In-N-In-N-In. In future, such tiny atomic arrangements might be created on purpose to achieve highly efficient light emission in other materials as well. Shuji Nakamura, one of the authors of this paper, first developed blue LEDs from nitride materials in 1993. For this achievement, he will receive Finland's Millennium Technology Prize on 8 September.

Author contact:
Shigefusa Chichibu (University of Tsukuba, Japan)
Tel: +81 29 853 5022; E-mail: [email protected]

[2] Molecules as ID tags
DOI: 10.1038/nmat1733

The molecular equivalent of radiofrequency identification (RFID) tags, which are often used as anti-theft devices in shops, is introduced in a study in the October issue of Nature Materials, under the name molecular computational identification (MCID).

The technique, developed by A P De Silva and colleagues, is suitable for encoding large populations of micro- and nanoscopic objects that could not be tagged with RFID devices, such as microbeads for combinatorial chemistry or cells in diagnostics. Specifically, the paper reports the encoding of microbeads by attaching them to mixtures of pH-sensitive fluorescent dyes and watching how the fluorescence changes when these molecular devices are contacted with solutions of different compositions. The fluorescence signal is easily and cheaply detected, and the authors estimate that it will be possible to produce tens of millions of distinct identification tags with this technique.

This work shows that molecular computation can be useful to deal with practical problems at a smaller length scale than is reachable with current technologies.

Author contact:

A Prasanna de Silva (Queen's University, Belfast, UK)
Tel: +44 28 9027 4422; E-mail: [email protected]

Other papers from Nature Materials to be published online at the same time and with the same embargo:

[3] Observation and tuning of hypersonic bandgaps in colloidal crystals
DOI: 10.1038/nmat1727

[4] Electrical control of antiferromagnetic domains in multiferroic BiFeO3 films at room temperature
DOI: 10.1038/nmat1731

[5] Ambient pressure colossal magnetocaloric effect tuned by composition in Mn1−xFexAs
DOI: 10.1038/nmat1732

************************************NATURE IMMUNOLOGY *************************

[6] & [7] Excess Wnt kills

DOI: 10.1038/ni1381
DOI: 10.1038/ni1387

Excessive stimulation of bone marrow stem cells in mice leads to severe anemia and ultimately death, according to research to be published in the October issue of Nature Immunology.

Hematopoietic stem cells residing in the bone marrow give rise to all blood cells circulating in the body. To ensure a lifelong supply of blood cells, these stem cells must continuously self-renew. Previous work revealed stem cells require a signaling molecule called Wnt to activate beta-catenin, a protein involved in self-renewal. Research from two groups shows that excessive beta-catenin signals lead instead to a loss of stem cells and problems in blood cell development. Mice expressing a mutant form of beta-catenin, engineered to be permanently switched on, died at a very young age due to defects in blood cell production. These findings suggest therapeutic manipulation of bone marrow stem cells via Wnt signals to achieve increased blood cell production needs to be finely balanced to avoid too much of a good thing.

Author contacts:

Claus Nerlov (EMBL Mouse Biology Unit, Monterotondo, Italy) Author paper [6]
Tel: +39 06 9009 1218; E-mail: [email protected]

Achim Leutz (Max-Delbrueck-Center for Molecular Medicine Tumorigenesis and Differentiation, Berlin, Germany) Author paper [7]
Tel: +49 30 94063735; E-mail: [email protected]

Other papers from Nature Immunology to be published online at the same time and with the same embargo:

[8] Smad6 negatively regulates interleukin 1-receptor-Toll-like receptor signaling through direct interaction with the adaptor Pellino-1

DOI: 10.1038/ni1383

[9] Clonal deletion of thymocytes by circulating dendritic cells homing to the thymus

DOI: 10.1038/ni1385

Items from other Nature journals to be published online at the same time and with the same embargo:

Nature MEDICINE (http://www.nature.com/naturemedicine)

[10] Cyclin-dependent kinase inhibitors enhance the resolution of inflammation by promoting inflammatory cell apoptosis
DOI: 10.1038/nm1468

[11] Cholesterol glucosylation promotes immune evasion by Helicobacter pylori
DOI: 10.1038/nm1480

NATURE GENETICS (http://www.nature.com/naturegenetics)

[12] Lamin B1 duplications cause autosomal dominant leukodystrophy
DOI: 10.1038/ng1872

[13] Deficiency of hyccin, a newly identified membrane protein, causes hypomyelination and congenital cataract
DOI: 10.1038/ng1870

[14] Biological function of unannotated transcription during the early development of Drosophila melanogaster
DOI: 10.1038/ng1875

[15] Indian hedgehog is a major mediator of progesterone signaling in the mouse uterus
DOI: 10.1038/ng1874

[16] Heritable germline epimutation of MSH2 in a family with hereditary nonpolyposis colorectal cancer
DOI: 10.1038/ng1866

Nature NEUROSCIENCE (http://www.nature.com/natureneuroscience)

[17] Focal adhesion kinase signaling at sites of integrin-mediated adhesion controls axon pathfinding
DOI: 10.1038/nn1762



The following list of places refers to the whereabouts of authors on the papers numbered in this release. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details.


Rio de Janeiro: 5

Sao Paulo: 5


Hong Kong: 16

Copenhagen: 6

Bayreuth: 11
Berlin: 7, 11
Borstel: 11

Hamburg: 11

Magdeburg: 11

Mainz: 3

Martinsried: 15

Munich: 15


Athens: 3

Heraklion: 3


Genoa: 13

Milan: 13

Monterotondo: 6


Iizuka City: 12

Kawaguchi: 1

Kyoto: 7

Kyushu: 12

Nagoya: 1

Osaka: 12

Shinjuku: 1

Tsukuba: 1

Yokohama: 1


Gyeonggi: 8

Incheon: 8


Ensenada: 4


Huddinge: 15

Lund: 6


Epalinges: 7


Amsterdam: 13


Belfast: 2

Edinburgh: 10

London: 10

Manchester: 2


Berkeley: 4, 14

San Francisco: 12

Santa Barbara: 1, 4

Santa Clara: 14

New Haven: 1

Bethesda: 8, 11, 12

Boston: 7, 9, 15
New York

Albany: 12

Pittsburgh: 4

Philadelphia: 13

Houston: 15


Madison: 4, 12, 17


For media inquiries relating to embargo policy for all the Nature Research Journals:

Helen Jamison (Nature London)
Tel: +44 20 7843 4658; E-mail: [email protected]

Ruth Francis (Senior Press Officer, Nature, London)
Tel: +44 20 7843 4562; E-mail: [email protected]

For media inquiries relating to editorial content/policy for the Nature Research Journals, please contact the journals individually:

Nature Genetics (New York)

Orli Bahcall
Tel: +1 212 726 9311; E-mail: [email protected]

Nature Immunology (New York)

Laurie Dempsey
Tel: +1 212 726 9372; E-mail: [email protected]

Nature Materials (London)

Maria Bellantone
Tel: +44 20 7843 4556; E-mail: [email protected]

Nature Medicine (New York)

Juan Carlos Lopez
Tel: +1 212 726 9325; E-mail: [email protected]

Nature Neuroscience (New York)

Sandra Aamodt (based in California)
Tel: +1 530 795 3256; E-mail: [email protected]

About Nature Publishing Group

Nature Publishing Group (NPG) is a division of Macmillan Publishers Ltd, dedicated to serving the academic, professional scientific and medical communities. NPG's flagship title, Nature, was first published in 1869. Other publications include Nature research journals, Nature Reviews, Nature Clinical Practice and a range of prestigious academic journals including society-owned publications. NPG also provides news content through [email protected] and scientific career information through Naturejobs.

NPG is a global company with headquarters in London and offices in New York, San Francisco, Washington DC, Boston, Tokyo, Paris, Munich, Hong Kong, Melbourne, Delhi, Mexico City and Basingstoke. For more information, please go to <www.nature.com>.

Published: 03 Sep 2006

Contact details:

The Macmillan Building, 4 Crinan Street
N1 9XW
United Kingdom

+44 20 7833 4000
News topics: 
Content type: 

Nature Research Journals