O primeiro LED

Em Outubro de 1962, o então jovem doutor Nick Holonyak apresentava ao mundo o primeiro LED (Light-Emitting Diode), um diodo emissor de luz.

Já se sabia que os diodos podiam emitir radiação na faixa do infravermelho, mas ninguém havia ainda conseguido fazê-los brilhar na faixa visível pelo olho humano.

Na época, a pesquisa com semicondutores ainda era emergente e quase uma curiosidade científica, em um mundo dominado pelas válvulas termoiônicas.

O primeiro transístor era um adolescente, e não tinha ainda completado 15 anos de idade.

O primeiro circuito integrado vinha na turma seguinte, com apenas 14 anos.

Mas os trabalhos com os masers, que levariam à descoberta do laser, fervilhavam, com vários grupos tentando criar dispositivos de estado sólido para a emissão de diversos comprimentos de onda. Devido à sua ligação com a GE, Holonyak queria fabricar um componente semicondutor que emitisse luz visível - em outras palavras, uma lâmpada.

"O Mágico"

Enquanto seu colega Robert Hall tentava construir um laser semicondutor no infravermelho usando GaAs (arseneto de gálio), Holonyak voltou-se para o espectro visível usando GaAsP (fosforeto arsenieto de gálio).

Em 9 de outubro de 1962, com toda a equipe assistindo, Holonyak tornou-se a primeira pessoa a operar um laser de liga semicondutora na faixa visível - o componente que iluminou o primeiro LED visível.

A equipe passou a chamar o primeiro LED visível de "o mágico", porque, ao contrário dos outros componentes, não era preciso olhar para os aparelhos para ver se ele estava funcionando.

Cinquenta anos depois, os LEDs estão em todos os aparelhos eletrônicos, TVs, monitores de computador, lanternas, semáforos, faróis de carros e uma infinidade de outras aplicações.

Lâmpada definitiva

O que ainda se espera é que os LEDs realizem a promessa de substituir de vez as lâmpadas incandescentes, que consomem energia demais, e as fluorescentes, que usam o perigoso mercúrio.

Apesar disso, o Dr. Holonyak chama seu pequeno "mágico" de "a lâmpada definitiva": "Porque a própria corrente elétrica é a luz," justifica ele.

Isso significa que um LED opera de forma energeticamente muito eficiente, com pouca perda de energia e uma dissipação de calor desprezível.

O grande entrave à sua utilização na iluminação residencial é que seu espectro de emissão não é contínuo, o que torna sua luz menos agradável aos olhos humanos.

Aos 83 anos, o cientista continua trabalhando na Universidade de Illinois, nos Estados Unidos, sempre em parceria com a empresa GE.

O Dr. Holonyak é responsável também por vários avanços mais recentes na área:

ACS Publications congratulates long time authors Robert J. Lefkowitz and Brian K. Kobilka on winning the 2012 Nobel Prize in Chemistry for their studies of G-protein-coupled receptors (GPCRs).  These receptors allow cells in the body to sense and respond to outside signals and are the target for several commonly prescribed prescription drugs including beta blockers, antihistamines and antidepressants.

ACS Publications also congratulates Accounts of Chemical Research author David Wineland, on the 2012 Nobel Prize in Physics.

1975-1980 / 1981-1985 / 1986-1990 / 1991-1995 / 1996-1999 / 2002-Current 

Conformational Dynamics of Single G Protein-Coupled Receptors in Solution
Samuel Bockenhauer, Alexandre Fürstenberg, Xiao Jie Yao, Brian K. Kobilka, and W. E. Moerner
The Journal of Physical Chemistry B 2011
View article -  DOI: 10.1021/jp204843r 

Tandem Facial Amphiphiles for Membrane Protein Stabilization Pil Seok Chae, Kamil Gotfryd, Jennifer Pacyna, Larry J. W. Miercke, Søren G. F. Rasmussen, Rebecca A. Robbins, Rohini R. Rana, Claus J. Loland, Brian Kobilka, Robert Stroud, Bernadette Byrne, Ulrik Gether, and Samuel H. Gellman
Journal of the American Chemical Society 2010
View article -  DOI: 10.1021/ja1072959 

Mass Spectrometric Analysis of Agonist Effects on Posttranslational Modifications of the β2-Adrenoceptor in Mammalian Cells Michelle Trester-Zedlitz, Al Burlingame, Brian Kobilka, and Mark von Zastrow
Biochemistry 2005
View article - DOI: 10.1021/bi0475469 

Plasmon-Waveguide Resonance Studies of Ligand Binding to the Human β2-Adrenergic Receptor Savitha Devanathan, Zhiping Yao , Zdzislaw Salamon, Brian Kobilka, and Gordon Tollin
Biochemistry 2004
View article - DOI: 10.1021/bi035825a 

β2-Adrenergic Receptor Stimulated, G Protein-Coupled Receptor Kinase 2 Mediated, Phosphorylation of Ribosomal Protein P2 Jennifer L. R. Freeman, Philippe Gonzalo, Julie A. Pitcher, Audrey Claing, Jean-Pierre Lavergne, Jean-Paul Reboud, and Robert J. Lefkowitz
Biochemistry 2002
View article - DOI: 10.1021/bi020145d 

Phosphorylation of β-Arrestin2 Regulates Its Function in Internalization of β2-Adrenergic Receptors Fang-Tsyr Lin, Wei Chen, Sudha Shenoy, Mei Cong, Sabrina T. Exum, and Robert J. Lefkowitz
Biochemistry 2002
View article - DOI: 10.1021/bi025705n 

Analysis of Biomolecular Interactions Using a Miniaturized Surface Plasmon Resonance Sensor Rebecca J. Whelan, Thorsten Wohland, Lars Neumann, Bo Huang, Brian K. Kobilka and Richard N. Zare
Analytical Chemistry 2002
View article - DOI: 10.1021/ac025669y 

Restricting the Mobility of Gsα: Impact on Receptor and Effector Coupling
Tae Weon Lee, Roland Seifert, Xiaoming Guan, and Brian K. Kobilka
Biochemistry 1999
View article - DOI: 10.1021/bi9908282 

Palmitoylation Increases the Kinase Activity of the G Protein-Coupled Receptor Kinase, GRK6 Robert H. Stoffel, James Inglese, Alexander D. Macrae, Robert J. Lefkowitz and Richard T. Premont
Biochemistry 1998
View article - DOI: 10.1021/bi981432d 

Ligand Stabilization of the β2 Adrenergic Receptor:  Effect of DTT on Receptor Conformation Monitored by Circular Dichroism and Fluorescence Spectroscopy Sansan Lin, Ulrik Gether, and Brian K. Kobilka
Biochemistry 1996
View article - DOI: 10.1021/bi961619+ 

Ras-Dependent Activation of Fibroblast Mitogen-Activated Protein Kinase by 5-HT1A Receptor via a G Protein βγ-Subunit-Initiated Pathway Maria N. Garnovskaya, Tim van Biesen, Brian Hawes, Shirley Casañas Ramos, Robert J. Lefkowitz and John R. Raymond
Biochemistry 1996
View article - DOI: 10.1021/bi961764n 

Members of the G Protein-Coupled Receptor Kinase Family That Phosphorylate the β2-Adrenergic Receptor Facilitate Sequestration Luc Ménard, Stephen S. G. Ferguson, Larry S. Barak, Lucie Bertrand, Richard T. Premont, Anne-Marie Colapietro, Robert J. Lefkowitz and Marc G. Caron
Biochemistry 1996
View article - DOI: 10.1021/bi952961+ 

Desensitization of the Isolated β2-Adrenergic Receptor by β-Adrenergic Receptor Kinase,cAMP-Dependent Protein Kinase, and Protein Kinase C Occurs viaDistinct Molecular Mechanisms Julie Pitcher, Martin J. Lohse, Juan Codina,Marc G. Caron, and Robert J. Lefkowitz
Biochemistry 1992
View article - DOI: 10.1021/bi00127a021 

Role of Acidic Amino Acids in Peptide Substrates of the β-Adrenergic Receptor Kinase and Rhodopsin Kinase
James J. Onorato, Krzysztof Palczewski, John W. Regan, Marc G. Caron, Robert J. Lefkowitz, and Jeffrey L. Benovic
Biochemistry 1991
View article - DOI: 10.1021/bi00235a002 

Functional Interactions of Recombinant α2 Adrenergic Receptor Subtypes and G Proteins in Reconstituted Phospholipid Vesicles
Hitoshi Kurose, John W. Regan, Marc G. Caron,and Robert J. Lefkowitz
Biochemistry 1991
View article - DOI: 10.1021/bi00227a024 

Role of Extracellular Disulfide-Bonded Cysteines in the Ligand Binding Function of the β2-Adrenergic Receptor
Henrik G. Dohlman, Marc G. Caron, Antonio DeBlasi, Thomas Frielle, and Robert J. Lefkowitz
Biochemistry 1990
View article - DOI: 10.1021/bi00461a018 

Localization of the Fourth Membrane spanning Domain as a Ligand Binding Site in the Human Platelet α2-Adrenergic Receptor Hiroaki Matsui, Robert J. Lefkowitz, Marc G. Caron, and John W. Regan
Biochemistry 1989
View article - DOI: 10.1021/bi00435a075 

Phosphorylation of Chick Heart Muscarinic Cholinergic Receptors by the β-Adrenergic Receptor Kinase Madan M. Kwatra, Jeffrey L. Benovic, Marc G. Caron, Robert J. Lefkowitz, and M. Marlene Hosey
Biochemistry 1989
View article - DOI: 10.1021/bi00437a005 

Identification and Sequence of a Binding Site Peptide of the β2-Adrenergic Receptor Henrik G. Dohlman, Marc G. Caron, Catherine D. Strader, Nourdine Amlaiky, and Robert J. Lefkowitz
Biochemistry 1988
View article - DOI: 10.1021/bi00406a002 

A Family of Receptors Coupled to Guanine Nucleotide Regulatory Proteins Henrik G. Dohlman, Marc G. Caron, and Robert J. Lefkowitz
Biochemistry 1987
View article - DOI: 10.1021/bi00384a001 

Functional Differences in the βγ Complexes of Transducin and the Inhibitory Guanine Nucleotide Regulatory Protein Richard A. Cerione, Peter Gierschik, Claudia Stanizsewski, Jeffrey L. Benovic, Juan Codina, Robert Somers, Lutz Birnbaumer, Allen M. Spiegel, Robert J. Lefkowitz, and Marc G. Caron
Biochemistry 1987
View article - DOI: 10.1021/bi00379a041 

A Novel Catecholamine-Activated Adenosine Cyclic 3',5'-Phosphate Independent Pathway for β-Adrenergic Receptor Phosphorylation in Wild-Type and Mutant S49 Lymphoma Cells: Mechanism of Homologous Desensitization of Adenylate Cyclase Ruth H. Strasser, David R. Sibley, and Robert J. Lefkowitz
Biochemistry 1986
View article - DOI: 10.1021/bi00354a027 

Transducin and the Inhibitory Nucleotide Regulatory Protein Inhibit the Stimulatory Nucleotide Regulatory Protein Mediated Stimulation of Adenylate Cyclase in Pospholipid Vesicle Systems Richard A. Cerione, Juan Codina, Brian F. Kilpatrick, Claudia Staniszewski, Peter Gierschik, Robert L. Somers, Allen M. Spiegel, Lutz Birnbaumer, Marc G. Caron, and Robert J. Lefkowitz
Biochemistry 1985
View article - DOI: 10.1021/bi00338a00 

The Mammalian β2-Adrenergic Receptor: Reconstitution of Functional Interactions Between Pure Receptor and Pure Stimulatory Nucleotide Binding Protein of the Adenylate Cyclase System Richard A. Cerione, Juan Codina, Jeffrey L. Benovic, Robert J. Lefkowitz, Lutz Birnbaumer, and Marc G. Caron
Biochemistry 1984
View article - DOI: 10.1021/bi00315a003 

The Mammalian β2-Adrenergic Receptor: Purification and Characterization Jeffrey L. Benovic, Robert G. L. Shorr, Marc G. Caron, and Robert J. Lefkowitz
Biochemistry 1984
View article - DOI: 10.1021/bi00315a002 

Determination of the Molecular Size of Frog and Turkey Erythrocyte β-Adrenergic Receptors by Radiation Inactivation Robert G. L. Shorr, Ellis S. Kempner, Mark W. Strohsacker, Ponnal Nambi, Robert J. Lefkowitz, and Marc G. Caron
Biochemistry 1984
View article - DOI: 10.1021/bi00299a025 

Synthesis of Iodine-125 labeled (+-)-15-[4-Azidobenzyl]carazolol: A Potent β-Adrenergic Photoaffinity Probe Sarah L. Heald, Peter W. Jeffs, Thomas N. Lavin, Ponnal Nambi, Robert J. Lefkowitz, and Marc G. Caron
Journal of Medicinal Chemistry 1983
View article - DOI: 10.1021/jm00360a009 

Parallel Modulation of Catecholamineactivation of Adenylate Cyclase and Formation of the High-Affinity Agonist Receptor Complex in Turkey Erythrocyte Membranes by Temperature and cis-Vaccenic Acid
Margaret M. Briggs and Robert J. Lefkowitz
Biochemistry 1980
View article - DOI: 10.1021/bi00560a012 

Structure and Biological Activity of(-)-[3H]-Dihydroalprenolol, a Radioligand for Studies of β-Adrenergic Receptors
Malcolm H. Randall, Lawrence J. Altman, and Robert J. Lefkowitz
Journal of Medicinal Chemistry 1977
View article - DOI: 10.1021/jm00218a020 

Pharmacological Activity of Nitroxide Analogs of Dichloroisoproterenol and Propranolol
Elmer J. Rauckman, Gerald M. Rosen, and Robert J. Lefkowitz
Journal of Medicinal Chemistry 1976
View article - DOI: 10.1021/jm00232a018 

Uma apresentação em flash interessante sugerida pelo doutorando do Grupo de Materiais Fotônicos do IQ - UNESP, Araraquara: Robson Rosa da Silva.

This is the first laser spectrum from the Chemistry and Camera (ChemCam) instrument on NASA's Curiosity rover, sent back from Mars on August 19, 2012. The plot shows emission lines from different elements present in the target, a rock near the rover's landing site dubbed "Coronation" .

The plot is a composite of spectra taken over 30 laser shots at a single 0.016-inch (0.4-millimeter) diameter spot on the target. An inset on the left shows detail for the minor elements titanium and manganese in the 398-to-404-nanometer range. An inset at the right shows the hydrogen and carbon peaks. The carbon peak was from the carbon dioxide in Mars' air. The hydrogen peak was only present on the first laser shot, indicating that the element was only on the very surface of the rock. Magnesium was also slightly enriched on the surface. The heights of the peaks do not directly indicate the relative abundances of the elements in the rock, as some emission lines are more easily excited than others. 

A preliminarily analysis indicates the spectrum is consistent with basalt, a type of volcanic rock, which is known from previous missions to be abundant on Mars. Coronation is about three inches (7.6 centimeters) across, and located about 5 feet (1.5 meters) from the rover and about nine feet (2.7 meters) from ChemCam on the mast. 

Image credit: NASA/JPL-Caltech/LANL/CNES/IRAP

http://www.nasa.gov/mission_pages/msl/multimedia/pia16089.html

Natural structural color materials, especially those that can undergo reversible changes, are attracting increasing interest in a wide variety of research fields. Inspired by the natural creatures, many elaborately nanostructured photonic materials with variable structural colors were developed. These materials have found important applications in switches, display devices, sensors, and so on. In this critical review, we will provide up-to-date research concerning the natural and bio-inspired photonic materials with variable structural colors. After introducing the variable structural colors in natural creatures, we will focus on the studies of artificial variable structural color photonic materials, including their bio-inspired designs, fabrications and applications. The prospects for the future development of these fantastic variable structural color materials will also be presented. We believe this review will promote the communications among biology, bionics, chemistry, optical physics, and material science.

NASA's Mars rover Curiosity has fired its laser for the first time on Mars. On Aug. 19th the mission's ChemCam instrument hit a fist-sized rock named "Coronation" with 30 pulses of its laser during a 10-second period. Each pulse delivers more than a million watts of power for about five one-billionths of a second.

The energy from the laser creates a puff of ionized, glowing plasma. ChemCam catches the light with a telescope and analyzes it with three spectrometers for information about what elements are in the rock. The spectrometers record 6,144 different wavelengths of ultraviolet, visible and infrared light.

"We got a great spectrum of Coronation -- lots of signal," said ChemCam Principal Investigator Roger Wiens of Los Alamos National Laboratory, N.M. "Our team is both thrilled and working hard, looking at the results. After eight years building the instrument, it's payoff time!"

ChemCam recorded spectra from each of the 30 pulses. The goal of this initial use of the laser on Mars was to serve as target practice for characterizing the instrument, but the activity may provide additional value. Researchers will check whether the composition changed as the pulses progressed. If it did change, that could indicate dust or other surface material being penetrated to reveal different composition beneath the surface.

"It's surprising that the data are even better than we ever had during tests on Earth, in signal-to-noise ratio," said ChemCam Deputy Project Scientist Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planetologie (IRAP) in Toulouse, France. "It's so rich, we can expect great science from investigating what might be thousands of targets with ChemCam in the next two years."

The technique used by ChemCam, called laser-induced breakdown spectroscopy, has been used to determine composition of targets in other extreme environments, such as inside nuclear reactors and on the sea floor, and has had experimental applications in environmental monitoring and cancer detection. Today's investigation of Coronation is the first use of the technique in interplanetary exploration.

More information about ChemCam is available at www.msl-chemcam.com .

fonte: http://science.nasa.gov/science-news/

If you watched the Olympics over the past few weeks, one of the recurring advertisements was for a luxury car (Cadillac or Lexus, I believe) that featured the car’s heads-up night vision system. I’ve always thought that night vision/thermal camera systems were a nifty idea—especially after experiencing some frighteningly foggy days—but, the truth is that such an option would not be extremely high on my list of desired accessories if I were in the market for a new car.

One factor is that, because these systems have solely been offered on high-priced vehicles, I have tended to assume, I think correctly, that these systems are very pricey. Although the systems have been offered on some vehicles since 2000, carmakers have been ambivalent about whether consumers wanted to pay for these systems and have acknowledged in years past that price has been a factor.

In 2005, discussion began about forming a European consortium project to develop a low-cost effective automotive far infrared camera for driver-vision applications. According to a story from that year on theOptics.org website, one project’s target was going to be the creation of an FIR microbolometer detector. At that point, one of the consortium members, Umicore, said it had developed a process for a chalcogenide glass that could be directly molded into a final lens shape as an alternative to grinding, polishing or diamond turning lenses for the microbolometer. (Previously, the materials of choice were crystalline materials, such as germanium, zinc selenide or zinc sulfide.)

However, it looks as though the project and funding (three years) didn’t come together until 2008 when the Infrared Imaging Components for Use in Automotive Safety Applications (ICU) was formed (pdf). It’s not clear to me what the status of the ICU is now, and the most recent information on the project’s website is dated 2010 (when the funding would have run out). They did, however, produce this video about the technology:

None of Germany’s Fraunhofer institutes were a part of the ICU group, however the Fraunhofer Institute for Mechanics of Materials stuck to the goal of developing low-cost chalcogenide glass-based IR lenses and now the institute says it has pretty much perfected the technology and cut costs 70 percent.

In a new press release from Fraunhofer IWM, one of the scientists working on lenses, Helen Müller, says, ”Instead of crystalline materials, we use the amorphous chalcogenide glass. Its softening temperature—that is, the temperature at which it can be formed—is low. Therefore, we can form it using non-isothermic hot stamping.” The institute already has a reputation for developing processes to mold high-quality glass surfaces.

Müller likens the new process of making the lenses to making waffles, with the chalcogenide glass being placed between two pressing tools. These tools are heated and, after a few minutes, cooled to below the softening temperature. The shape of the press surfaces determines the final lens configuration. The researchers assert that no additional processing is needed to get an optical imaging quality equal to polished crystal.

Fraunhofer IWM says the next steps involve tweaking the process so that it can be adapted to cost-effective mass production.

The institute also has in mind markets beyond the auto industry. If the production can be scaled up and the total price driven down, Fraunhofer IWM projects that the technology could be used for such things as monitoring the movements of health-fragile populations (e.g., older people in danger of falling or being too sedentary), monitoring industrial production (by tracking manufacturing temperatures and employee heat exposure) and continuous energy auditing of buildings.

fonte: http://ceramics.org/ceramictechtoday/2012/08/14/