Terahertz wave activates filamentation of actin: A novel possibility of manipulating cellular functions Read more at: https://phys.org/news/2018-08-terahertz-filamentation-actin-possibility-cellular.html#jCp

Credit: Tohoku University

https://phys.org/news/2018-08-terahertz-filamentation-actin-possibility-cellular.html

A team of researchers has discovered that terahertz (THz) wave irradiation activates the filamentation of actin protein. Drs. Shota Yamazaki and Masahiko Harata (Graduate School of Agricultural Science, Tohoku University); Dr. Yuichi Ogawa (Graduate School of Agriculture, Kyoto University); Dr. Hiromichi Hoshina (THz imaging and the sensing team at RIKEN); and Dr. Toshitaka Idehara (FIR-UF at University of Fukui) have made this important discovery, which offers a new possibility for the manipulation of cellular functions.

Actin forms filaments through its polymerization in cells, and functions as a major component of cellular architecture. Actin plays a central role in various cellular functions, including wound healing and the metastasis of cancer cells. In addition, a portion of actin exists in the cell nucleus and regulates gene regulation. For example, actin is required for gene reprograming, which is required for establishing iPS (induced pluripotent) cells. In this research, the polymerization reaction of purified actin protein was monitored under irradiation of THz wave, and it was found that the THz wave activates the filamentation of actin.Due to the recent development of high power THz (1012 Hz) wave sources, many researchers have begun to explore its application for material manipulation. One of the advantages of THz wave irradiation is its lower photon energy as compared to visible light. Therefore, THz wave prevents the ionization of molecules. THz wave enables "soft" manipulation of macromolecules such as proteins, enabling changes to their higher-order structure without damaging the samples.

Actin governs various functions of cells. Therefore, a variety of drugs have been developed for controlling actin filamentation, and applications of these drugs for medical purposes have been explored. However, these drugs are inefficient in their delivery into, and clearance from, cells. THz irradiation is a non-invasive method and could overcome these identified problems in drugs. THz wave is expected to become a novel tool for the manipulation of cellular functions through modifying actin filamentation. This research team is now trying to understand the basic mechanism of the THz assisting filamentation to extend this technology to various proteins so that THz irradiation can be widely applied to various biological technologies.

Using terahertz laser, scientists change the macromolecular conformation of a polymer

Scientists from the RIKEN Center for Advanced Photonics (RAP) have, for the first time, successfully used a terahertz laser to induce permanent changes in the conformation of a polymer, giving it an increased pattern of crystallization. Conformational changes are very important for macromolecular science because they can change the characteristics of a material and, in the case of proteins, can make it either possible or impossible for them to perform a certain biological function. The work, done in collaboration with Osaka University, was published in Scientific Reports.
https://www.sciencedaily.com/releases/2016/06/160607080350.htm

According to Hiromichi Hoshina of RAP, "Terahertz lasers offer promise as a way to modify materials, because they resonate at a frequency close to the oscillations of the hydrogen bonds that bind polymers into certain conformations, but are much lower in energy than the covalent bonds that make up the molecular structure of the polymers. As a result, they could offer a 'soft' way to change the conformation without inducing chemical changes."

One of the difficulties, however, of using terahertz wave irradiation to induce changes is that the materials tend to revert very quickly to the state of thermal equilibrium states. To overcome this challenge, the group decided to perform experiments on a polymer undergoing solvent casting crystallization -- a process through which the conformation is fixed. This allowed them to effectively "fix" the results of the work and detect any changes.

The experiment was successful. When the group irradiated a polymer -- a poly(3-hydroxybutylate)/chloroform solution -- with terahertz radiation with a peak power of 40 megawatt/cm2, using a terahertz free electron laser FEL -- developed by the Institute of Scientific and Industrial Research at Osaka University, they found that the crystallization of the material was increased by 20%.

"We were happy with these results, but we were also surprised by what we saw," continues Hoshina."The researchers were intrigued, however, by the fact that the peak power used in this study was quite lower than previous reports using NIR and visible lasers. They considered that the crystallization might have been caused by changes in temperature, but measured it and found that the difference between regions was less than 1 degree Celsius, much too small a difference to account for the difference. They also considered that the terahertz waves might have directed caused increased vibrations between the molecules but did not find any significant correlations with the wavelength -- something that should have happened if the effect was due to differences in resonance.

According to Hoshina, "We have, for the first time, shown that terahertz waves can effectively induce a rearrangement of the molecules in polymer macromolecules. The exact mechanism through which this happens remains a mystery, though we speculate that it might be related to the generation of shockwaves in the material, and we plan future work to find out exactly what is special about these terahertz waves, which have often been called the 'unexplored frontier of the electromagnetic spectrum'."

"We are excited by this work," he continues, "as this could give us a new tool for controlling the structure of 'fragile' molecules and allowing us to discover new functional materials."

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Story Source:

The above post is reprinted from materials provided by RIKEN. Note: Materials may be edited for content and length.

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Journal Reference:

1. Hiromichi Hoshina, Hal Suzuki, Chiko Otani, Masaya Nagai, Keigo Kawase, Akinori Irizawa, Goro Isoyama. Polymer Morphological Change Induced by Terahertz Irradiation. Scientific Reports, 2016; 6: 27180 DOI: 10.1038/srep27180

Tuning in to soft vibrations

http://www.nanowerk.com/nanotechnology-news/newsid=42837.php

(Nanowerk News) Useful structural information can be teased from metal cluster complexes by tickling them with terahertz radiation, RIKEN researchers have shown. By applying the recently developed technique of terahertz absorption spectroscopy to analyze a copper-rich metal cluster complex, they showed that the technique can deepen our understanding of the structure and behavior of metal cluster complexes ("A terahertz absorption spectroscopy study of structural changes in D-penicillaminato CuI8CuII6 clusters induced by water desorption").

Metal cluster complexes are important molecules in nature and industry alike: they help plant leaves capture energy from sunlight as a key cog in the machinery of photosynthesis and are used as powerful catalysts in industry.

But to fully understand each cluster’s mode of action, better information is needed about the structure of these clusters and their aggregates, says Hal Suzuki of the RIKEN Center for Advanced Photonics. “Most structural studies of these substances have used x-ray diffraction, but it has a weak point—the target material must be a crystal,” he says. Since terahertz spectroscopy does not require crystals, it is expected to become a powerful analytical tool.

As its name suggests, terahertz spectroscopy probes compounds using terahertz radiation, which has shorter wavelengths than microwaves but longer wavelengths than infrared. It is similar to infrared spectroscopy in that it extracts structural information by picking up characteristic vibrations in the molecule being analyzed. But whereas infrared spectroscopy detects high-frequency vibrations between individual atoms in a structure, terahertz spectroscopy listens for low-frequency ‘soft’ vibrations, such as those of metal clusters in an aggregate.

Figure 1: Copper-rich metal clusters can form several different aggregates, including this cubic structure, which was analyzed using the technique of terahertz absorption spectroscopy.

To demonstrate the technique’s potential for studying these structures, Suzuki and another RIKEN researcher, Chiko Otani, collaborated with two researchers from Osaka University to analyze a recently discovered metal cluster complex that contains 14 copper ions (Fig. 1). These complexes form large, porous aggregates whose voids are filled with water molecules.

“By slightly tweaking its synthesis conditions, this cluster complex can be aggregated into different crystal structures,” Suzuki explains. “It can thus be used as a model substance to reveal the general rules behind aggregation of cluster complexes.”

Using terahertz spectroscopy, the researchers were able to track structural changes in each aggregate as it was heated to drive out the water molecules. The technique revealed that the aggregates became disordered as the component clusters became distorted by the loss of water molecules.

“There is still more that terahertz spectroscopy, in combination with other techniques, can tell us about these complexes,” Suzuki says. “The next step is to reveal the role of water molecules in building up the cluster complexes as well as the crystalline forms.”

Source: RIKEN

Read more: Tuning in to soft vibrations 

A*STAR AND RIKEN CELEBRATE 10 YEARS OF RESEARCH COLLABORATION

http://www.news.gov.sg/public/sgpc/en/media_releases/agencies/astar/press_release/P-20150803-1

Singapore—The Agency for Science, Technology and Research (A*STAR) and RIKEN, Japan's largest comprehensive research institute in the natural sciences, have marked a 10-year milestone of research partnership.

A*STAR and RIKEN inked their first MOU September 2005 to encourage more opportunities for scientific exchange between Singapore and Japan. The MOU has since been renewed three times. For a timeline of milestones, refer to Annex A.

RIKEN established its first overseas international liaison office in 2006, attesting to its long-term commitment to the partnership with Singapore. The partnership has catalysed joint projects in fields ranging from the biomedical sciences to the physical sciences and engineering domains (enclosed within and in Annex B). This partnership has also offered opportunities to broaden scientific exchange through RIKEN’s prestigious summer programmes in brain science and immunology.

The most recent renewal of the MOU will further build on the existing partnership to include mutual areas of interest in material science. This will continue to encourage sharing of ideas, co-advancing scientific capabilities, broadening research networks, and developing research talent.

Collaborative projects between A*STAR and RIKEN

·         Biomaterials and hydrogels: Dr Loh Xian Jun from A*STAR’s Institute of Materials Research and Engineering (IMRE) and Prof Yoshihiro Ito from RIKEN have successfully pioneered a new method of cell detachment using a novel temperature-sensitive biomaterial. This method has many applications in basic research, allowing scientists to better study adult human stem cells more efficiently. Currently, the process requires complicated chemical synthesis techniques whereas the new approach uses a “Drop-and-Dry” coating method. This method allows non-chemists to prepare their own temperature responsive cell culture surface for non-enzymatic detachment. This method will simplify experiments and facilitate the understanding of the cell differentiation process..

·         Identification of novel immune cell subset: Dr Florent Ginhoux from A*STAR’s Singapore Immunology Network (SIgN) is collaborating with Dr Ichiro Taniuchi from the RIKEN Center for Integrative Medical Sciences, to characterize novel lymphoid populations in the epidermis. Tapping on IMS’s strength in generating gene-manipulated mice and on SIgN’s flow cytometry and bioinformatics analyses of small cell populations, the collaboration identified a novel lymphoid cell subset in the epidermis in mice and humans. This finding, which will soon be published in Nature Scientific Reports, has provided new insights into the skin’s immune system and will deepen our understanding of the physiological and pathological roles of these new cell types during immune responses at the interface between our body and the environment.

Mr Lim Chuan Poh, Chairman A*STAR, said: “I am pleased that A*STAR’s and RIKEN’s longstanding partnership has catalysed many opportunities for collaboration in R&D between Singapore and Japan. We will continue to build on the complementary research capabilities of both countries through joint projects and scientific exchange. I look forward to many more fruitful years of collaboration.”

Dr Hiroshi Matsumoto, President of RIKEN, said: “RIKEN’s collaborations with Singapore through A*STAR have been extremely meaningful to us. A major mission of science today is to ensure the continued survival of humanity, and this mission cannot be accomplished without international cooperation. I strongly hope that our partnership will continue to develop, leading to important research breakthroughs that will benefit all of humanity.”

__________________________________________________________

.....

ii)            Safer X-Rays – Improving T-Rays for Potential Applications in Diagnostics and Security

 

A*STAR	RIKEN
Dr Gong Yandong Scientist, Institute for Infocomm Research (I2R)	Dr Hiroaki Minamide Team Leader, Tera-Photonics Research Team, RIKEN Center for Advanced Photonics
Expertise in Terahertz polarization, focus of collaboration is on the polarization sub-system and algorithms	Strength lies in basic terahertz frequency domain spectroscopy (THz-FDS) system

Terahertz (THz) is an underexplored band of light located between microwave and infrared frequency in the electromagnetic (EM) spectrum. THz radiation, also known as T-rays, produces images faster than X-rays and has a lower photon energy, making it safer and more efficient for use in various applications, such as in the detection of cancerous tumours for non-invasive, high-sensitivity medical diagnostics, or the detection of concealed objects during security screening.

However, most conventional THz systems can only provide basic parameters for the user. In this project with RIKEN, the researchers demonstrated the world-first polarimetric THz-FDS system. The ability to provide polarization information makes the THz system more powerful in detection and sensing. Out of this collaboration, the team also developed a new device on the market – the achromatic Terahertz waveplate. This device can be adapted for use in conventional THz systems, allowing THz polarization to be manipulated for greater control and more precise results. The THz polarization technology has been licensed to two local SMEs in the imaging and photonics industry.

Quantization of 'surface Dirac states' could lead to exotic applications

http://phys.org/news/2015-04-quantization-surface-dirac-states-exotic.html

Researchers from the RIKEN Center for Emergent Matter Science in Japan have uncovered the first evidence of an unusual quantum phenomenon—the integer quantum Hall effect—in a new type of film, called a 3D topological insulator. In doing this, they demonstrated that "surface Dirac states"—a particular form of massless electrons—are quantized in these materials, meaning that they only take on certain discrete values. These discoveries could help move science forward toward the goal of dissipationless electronics—electronic devices that can operate without producing the vast amounts of heat generated by current silicon-based semiconductors.

Topological insulators are an unusual type of material, which do not conduct electricity in the inside but only on the surfaces. Their surfaces are populated by massless electrons and electron holes—known as Dirac fermions—which can conduct electricity in a nearly dissipationless fashion, like a superconductor. As a result, their properties are being studied in an intense way with the hope of creating low-power consumption electronic devices. However, impurities in the crystal structures of these topological conductors have, up to now, made it difficult to realize this potential.

In the current research, published in Nature Communications, the group was able to overcome these limitations through careful engineering of the material. The group fabricated a 3D topological conductor made from bismuth, antimony, and tellurium, successfully eliminating the impurities that have plagued previous efforts. By fixing the material on an indium phosphide semiconductor substrate and then placing an insulating oxide film and electrodes on top, they transformed the films into electric gating devices known as "field effect transistors," and measured the Hall resistance, a type of electric resistance, while tuning the strength of the electric field, using a constant magnetic field. By doing this, they were able to show that the resistance became constant at certain plateaus, demonstrating the presence of the quantum Hall effect in the material.

In addition, by tuning the external voltage placed on the films, they were able to show that the Dirac states could be switched between the integer quantum Hall state and insulating state by changing the electrical current.

According to Ryutaro Yoshimi of the Strong Correlation Physics Research Group, who led the research, "It was very exciting to see this exotic effect in a 3D topological insulator, and we plan to continue our work to show how materials can be finely tuned to have various electronic properties. In the future, these results could I hope be used for the creation of high-speed and low-power-consumption electronic elements."

 Explore further: Scanning tunneling microscopy reveals the exotic properties of an unusual type of electron

Multiferroic material displays a novel spin structure that allows light to travel in only one direction

Figure 1: Multiferroics have a screw spin structure (arrows) with clockwise (lower) and anticlockwise (upper) orientations that can control the propogation of light at terahertz and gigahertz frequencies. Credit: Youtarou Takahashi, RIKEN Center for Emergent Matter Science

http://phys.org/news/2014-10-multiferroic-material.html#jCp

A research team led by Youtarou Takahashi from the RIKEN Center for Emergent Matter Science has demonstrated a novel phenomenon called magnetochiral dichroism, which prevents light from propagating parallel or antiparallel to the direction of magnetization. The discovery, which was made in the multiferroic 'helimagnet' gallium-doped copper iron oxide, could lead to new possibilities in the control of light at gigahertz and terahertz frequencies.

Multiferroic materials exhibit both magnetic order and an electric polarization property called ferroelectricity. These properties are determined by the polarization of electron 'spin' in the multiferroic lattice. Scientists have recently taken a particular interest in multiferroics with spiral or helical spin structures, known as helimagnets. Theory predicts that the combination of spin helicity and magnetization in these materials could result in a novel form of magnetoelectric coupling called magnetochiral dichroism, in which helical or chiral electric and magnetic polarizations combine to form a dynamic electromagnetic field that can interact with light passing through the material.

The multiferroic mixed oxide has a longitudinal helical or 'conical screw' spin structure due to competition between exchange interactions and geometric frustration among iron ions (Fig. 1). The conical screw spin structure provides the electronic chirality and magnetization that are required for magnetochiral dichroism. The inclusion of gallium in the material, a non-magnetic element, helps to stabilize the spin structure, which is needed to drive the novel optical phenomenon.

The researchers examined the multiferroic material using terahertz spectroscopy and discovered that a reversal of electronic chirality or magnetization reversed the direction of magnetochiral dichroism. They also found that the propagation of light against the direction of the magnetochiral dichroism was severely inhibited, with a high absorbance or extinction coefficient at gigahertz and terahertz frequencies.

The results suggest that multiferroic materials such as gallium-doped copper iron oxide could be used to control the propagation of electromagnetic waves in new ways, with implications for the development of isolators and optical devices that only permit the transmission of light in one direction.

Takahashi believes that magnetochiral dichroism, which differs from other forms of directional dichroism such as magnetic circular dichroism, is likely to be a common property of multiferroic materials with conical screw spin structures and arises through collective optically active spin wave excitations known as electromagnon resonance.

"This multiferroic material has an extinction coefficient of up to 400 per cent," says Takahashi. "Our achievement opens a new door for applications in gigahertz and terahertz optics, such as isolator and controllable filter devices."

 Explore further: Structured light make circular holes distinguish between left and right

More information: Kibayashi, S., Takahashi, Y., Seki, S. & Tokura, Y. "Magnetochiral dichroism resonant with electromagnons in a helimagnet." Nature Communications 5, 4583 (2014). DOI: 10.1038/ncomms5583

Read more at: http://phys.org/news/2014-10-multiferroic-material.html#jCp

New Crystal Research Study Results Reported from RIKEN

New Crystal Research Study Results Reported from RIKEN (Kinetics of Polymorphic Transitions of Cyclohexanol Investigated by Terahertz Absorption Spectroscopy)

http://www.4-traders.com/news/New-Crystal-Research-Study-Results-Reported-from-RIKEN-Kinetics-of-Polymorphic-Transitions-of-Cyclo--19001092/

By a News Reporter-Staff News Editor at Journal of Technology -- A new study on Crystal Research is now available. According to news reporting from Miyagi, Japan, by VerticalNews journalists, research stated, "The phase behaviors and kinetics of the polymorphic transitions of cyclohexanol, C6H11OH, were investigated by terahertz absorption spectroscopy over the temperature range of 150-330 K. A new phase was found, labeled phase I', which is more stable than the previously observed phase I but less stable than phase III'. The kinetics of the irreversible transitions from phase I to I', phase I to III', and phase III' to III were analyzed using Avrami's theory."

The news correspondents obtained a quote from the research from RIKEN, "The transition geometries of the first two transitions were found to be one-dimensional, while the latter was two-dimensional. The transitions from phase I to III and phase III to II were revealed to occur through two-step processes."

According to the news reporters, the research concluded: "The mechanism of these irreversible transitions is discussed in relation to the formation and dissociation of hydrogen bonds between the hydroxyl groups as well as the steric restriction effects of the cyclohexyl ring."

For more information on this research see: Kinetics of Polymorphic Transitions of Cyclohexanol Investigated by Terahertz Absorption Spectroscopy. Crystal Growth & Design, 2014;14(8):4087-4093. Crystal Growth & Design can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Crystal Growth & Design - www.pubs.acs.org/journal/cgdefu)

Our news journalists report that additional information may be obtained by contacting H. Suzuki, RIKEN, Aoba Ku, Sendai, Miyagi 9800845, Japan. Additional authors for this research include H. Hoshina and C. Otani.

Keywords for this news article include: Miyagi, Japan, Asia, Crystal Research

Colossal optical isolator effect driven by spin helix

Demonstration of gigahertz and terahertz optical devices

http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/colossal-optical-isolator-effect-driven-by-spin-helix/

A research group at the University of Tokyo Graduate School of Engineering, consisting of Project Associate Professor Y. Takahashi, graduate student S. Kibayashi and Professor Y. Tokura (concurrently Director, CEMS RIKEN) and CEMS Riken unit leader S. Seki, have discovered a new optical functionality of helical electron spin structures that emerge in matter and by which the optical absorption of counter-propagating light beams is greatly differentiated.

© 2014 Youtarou Takahashi.
When a helical spin structure shows up in matter, the light coming from the left side transmits, but the light coming from the right side is absorbed on the resonance of the electromagnon.

The research group found that the electromagnon, a kind of collective spin motion, emerges in the gigahertz to terahertz frequency range when the helical electron spin structure is present. Due to the helical electron spin structure possessing both “magnetism” and “chirality,” it was further discovered that the electromagnon exhibits a colossal magnetochiral effect. Using this magnetochiral effect, the research group succeeded in altering the extinction coefficient by up to 400 % depending on the propagation direction of light beams.

Research and development of optical devices for control of light (electromagnetic waves) in the frequency region including the higher gigahertz and terahertz, which is expected to be used for applications including future high capacity communications. The current result may be used for the development of optical devices such as isolators that only permit light to pass in one direction and optical devices for the control of light via external electrical and magnetic signals.

Press release

Paper

S. Kibayashi, Y. Takahashi, S. Seki and Y. Tokura,
“Magnetochiral dichroism resonant with electromagnons in a helimagnet”,
Nature Communications 5: 4583 Online Edition: 2014/8/1 (Japan time), doi: 10.1038/ncomms5583.
Article link

Links

Graduate School of Engineering

Quantum-Phase Electronics Center, Graduate School of Engineering

Department of Applied Physics, Graduate School of Engineering

Takahashi Laboratory, Quantum-Phase Electronics Center, Graduate School of Engineering (Japanese)

Colossal optical isolator effect driven by spin helix -Demonstration of the new gigahertz and terahertz optical devices

Colossal optical isolator effect driven by spin helix -Demonstration of the new gigahertz and terahertz optical devices- ： Project Associate Professor Youtaro Takahashi,　Quantum-Phase Electronics Center

http://www.t.u-tokyo.ac.jp/etpage/release/2014/2014080401.html

  Y. Takahashi (associate professor, University of Tokyo), S. Kibayashi (graduated student, University of Tokyo), S. Seki (unit leader, CEMS Riken) and Y. Tokura (professor, University of Tokyo, director, CEMS Riken) discovered new optical functionality of the helical spin structure, which differentiates the optical absorption between the counter-propagating light beams.

   They found that the emergence of the electromagnon, which is a kind of collective spin motion, in the frequency range of gigahertz to terahertz, when the helical spin structure shows up.  Due to the presence of the both “magnetism” and “chirality” by the helical spin structure, the electromagnon exhibits the colossal magnetochiral effect, leading to the changes of the extinction coefficient up to 400 % depending on the propagation direction of light beams.

   In the frequency region including the higher gigahertz and terahertz, which is expected for future high capacity communication etc., the optical device is developing.  The current results will be used for the possible optical devices, such as an isolator, and the electrically and magnetically controllable optical elements.

New Findings on Molecular Structures from RIKEN Summarized (Separation of overlapping vibrational peaks in terahertz spectra using two-dimensional correlation spectroscopy)

http://www.4-traders.com/news/New-Findings-on-Molecular-Structures-from-RIKEN-Summarized-Separation-of-overlapping-vibrational-pe--18792167/

By a News Reporter-Staff News Editor at Science Letter -- Investigators publish new report on Molecular Structures. According to news reporting out of Miyagi, Japan, by NewsRx editors, research stated, "In this study, the terahertz (THz) absorption spectra of poly(3-hydroxybutyrate) (PHB) were measured during isothermal crystallization at 90-120 degrees C. The temporal changes in the absorption spectra were analyzed using two-dimensional correlation spectroscopy (2DCOS). In the asynchronous plot, cross peaks were observed around 2.4 THz, suggesting that two vibrational modes overlap in the raw spectrum."
Our news journalists obtained a quote from the research from RIKEN, "By comparing this to the peak at 2.9 THz corresponding to the stretching mode of the helical structure of PHB and the assignment obtained using polarization spectroscopy, we concluded that the high-frequency band could be attributed to the vibration of the helical structure and the low-frequency band to the vibration between the helical structures. The exact frequencies of the overlapping vibrational bands and their assignments provide a new means to inspect the thermal behavior of the intermolecular vibrational modes."
According to the news editors, the research concluded: "The large red-shift of the interhelix vibrational mode suggests a large anharmonicity in the vibrational potential."
For more information on this research see: Separation of overlapping vibrational peaks in terahertz spectra using two-dimensional correlation spectroscopy. Journal of Molecular Structure, 2014;1069():152-156.Journal of Molecular Structure can be contacted at: Elsevier Science Bv, PO Box 211, 1000 Ae Amsterdam, Netherlands. (Elsevier - www.elsevier.com; Journal of Molecular Structure - www.elsevier.com/wps/product/cws_home/500850)
Our news journalists report that additional information may be obtained by contacting H. Hoshina, RIKEN, Aoba Ku, Sendai, Miyagi 9800845, Japan. Additional authors for this research include S. Ishii and C. Otani (see also Molecular Structures).
Keywords for this news article include: Miyagi, Japan, Asia, Molecular Structures
Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC

(c) 2014 NewsRx LLC

Abstract & presentation-Nonlinear Optical Wavelength-conversion Between Wave and Light for Terahertz-Wave Generation and Detection

 Hiroaki Minamide

Tera-photonics Team, RIKEN

what	Visitor Seminars
when	Jun 06, 2014 from 03:00 PM to 04:00 PM
where	Engr. IV Bldg., Maxwell Room 57-124
contact name	Prof. Mona Jarrahi

http://ee.ucla.edu/events/events-archive/2014/nonlinear-optical-wavelength-conversion-between-wave-and-light-for-terahertz-wave-generation-and-detection

Abstract

The development of nonlinear optical techniques has been extended into the terahertz (THz)-wave region, while THz waves have proved to be very attractive to both fundamental science and advanced industrial applications in recent years. In the early stage of THz research, we proposed a tunable THz-wave source is essential to exploit the underdeveloped THz region because no one knows which frequency is significant. We have developed coherent tunable THz-wave sources covering an ultra-wide spectral range [1-3] and the output power of our sources has been increasing. The developed THz-wave sources were based on both inorganic LiNbO₃ (LN) and organic (DAST and BNA) crystals. Organic ones cover ultra-wide range from 0.5 to 50 THz, while LN 1 to 3 THz range. As for the output power, the peak-power reached kW-level for injection-seeded LN THz-wave parametric generator [4].

And also, the highly sensitive THz detection [5-7] in room temperature has been developed. By using reverse nonlinear process, THz-wave is up-converted to infrared optical wave, which enables to extract the information of THz wave including both amplitude and phase information. The high-sensitivity, rapid-response THz-wave detection at room temperature was carried out. By using DAST crystal, it is possible to realize ultra-wide frequency range with NEP of the pW/Hz^1/2 at the room-temperature. Higher sensitivity using LN crystal was confirmed (~20pW/Hz^1/2) compared to a typical liquid-He-cooled Si bolometer. The minimum detectable input power of terahertz-wave was less than 1 μW, corresponding dynamic range of more than 100 dB.

In this seminar, we report on widely tunable THz-wave sources and sensitive THz detection using nonlinear optical up-conversion.

Focus on RIken and NICT Terahertz Database

My Note: Thanks to Piero TeHdeschi,  for posting a link to this THz, database.
http://thzdb.org/
The website provides:
In 2007, two publicly viewable online databases have been developed in Japan; RIKEN THz Database and Terahertz Spectral Database from NICT. The former contains around 200 spectra of pure reagent-grade materials, obtained with specified procedures. Text data are also provided with precise information about the measurement conditions. The later contains also around 200 spectra of materials used in art and art conservation, designed to demonstrate the applicability of terahertz spectroscopy in a certain field. We believe that the establishment of the spectral database is essential for THz spectroscopy or THz technology to be a common tool in industries and academics in various research fields, as we have commercial spectral library in mid-infrared spectroscopy.

The two organisations agreed to merge all data even though the applicable fields and quantitativeness are different. The aim of this project is to collect spectra which are useful in any fields, obtained by any system at any conditions by inviting contribution from organisations. This 'platform' should trigger the activity of accumulating spectral database, and encourage the practical use in various research fields around the globe.

This new keyword searchable database contains approximately 500 spectra, including contributions from Laboratory of Terahertz Bio-engineering of Tohoku University.

Keyword can be a part of material common name (casein, etc.), system (TDS, FTIR), mode (Transmission, Reflection), or organisation which carried out the measurement (NICT, RIKEN etc. )

We request that when you use the data of our Terahertz Database in your publication or presentation, a proper acknowledgement or reference is given as follows: Terahertz Database : http://www.thzdb.org

We are preparing a guideline for participation, including the data format of submission, and will organise a committee for database maintenance. Contributors retain the copyright on their own submitted data. If you are planning to participate to this database project, please do not hesitate to contact us.

Terahertz performs noninvasive mail inspection

 My note: I just saw this somewhat dated story on the Yahoo MB. It's notable, as it provides concrete evidence of another THz  application we will see in the near future.

Hiromichi Hoshina, Yoshiakim Sasaki, Aya Hayashi, Chiko Otani, and Koko Kawase

Telltale spectra can identify illicit drugs hidden in packages.

24 February 2009, SPIE Newsroom. DOI: 10.1117/2.1200902.1505

 Detecting hazardous materials and illicit drugs inside posted mail is necessary because of security concerns and to deter drug trafficking. In Japan, confidentiality of private mail is guaranteed by law, and only noninvasive inspection methods are permitted. Detection (sniffer) dogs and x-ray imaging have been used, but x-rays cannot identify suspect materials and dogs are only useful if drug vapors leak from a package.

Systems using terahertz (THz) radiation have recently been demonstrated as quick and reliable mail-inspection devices.^1–4 Like radio waves, THz radiation is not significantly scattered by soft materials such as paper, wood, and plastics, and creates clear images of hidden objects. In addition, many materials exhibit unique THz-absorption spectra—fingerprint spectra—which can be used to identify the contents of suspicious packages.
A prototype apparatus has been built to inspect all mail handled in Japanese international post offices (around 100,000 items per day). However, the THz spectrometer takes too long to examine every package. Therefore, to achieve complete inspection, the process has been divided into two stages. The first involves rapid screening using x-rays and THz waves, and the second identifies the suspicious substances selected in the first stage. The initial screening stage uses x-rays to exclude envelopes containing only paper. Images revealing shadows are then scanned and measured at 0.54THz. A diagram of the THz system is shown in Figure 1.

Figure 1. (top) THz rapid-screening system. A Schottky diode is characterized by a very low forward-voltage drop. (bottom) THz-scattering signal intensity of sucrose powder of different particle sizes. The Mie-scattering extinction curves are for nonabsorbing (solid line) and partially absorbing spheres (dashed line). The data point labeled ‘envelope’ illustrates the extinction for a paper-only envelope.

According to Mie scattering theory,⁵ which describes electromagnetic-radiation scattering by spherical particles, THz waves are intensely scattered when the particle size is comparable to the wavelength. Our experiment confirms that powders with particle sizes greater than 100μm result in a significantly stronger scattering signal than empty envelopes. Therefore, the rapid-screening system flags envelopes showing strong THz-wave scattering as suspicious mail.
Substance identification is achieved with a THz time-domain spectrometer (based on time-resolved Fourier-transform spectroscopy) using femtosecond laser pulses. The absorption spectra are obtained from 0.1 to 3THz with a frequency resolution of 0.03THz and a measurement time of two minutes. Figure 2 shows typical spectra of (a) empty envelopes and (b) folders containing methamphetamine hydrochloride powder. The empty envelopes show weak absorption and almost no spectral features, while those containing methamphetamine hydrochloride show strong absorption and fingerprint peaks at 1.2, 1.6, and 1.8THz. The spectral baselines in Figure 2(b) increase gradually with frequency due to the powder's scattering properties, and reach the detection limit at 2.4THz.

Figure 2. (a) THz absorption spectra of different kinds of empty envelopes. (b) THz absorption spectra of methamphetamine hydrochloride (HCl) with a particle size of 170μm and (c) first derivative. (d) First derivative of the database spectrum of methamphetamine HCl. Dashed lines show the frequency range used for calculating the correlation coefficients.

To identify controlled substances, we assembled a THz-spectrum database of widely used chemicals and drugs. Most of these show clear fingerprint spectra at 0.5–3THz, with different peaks, positions, and line shapes for each chemical. Any match between the spectra of suspicious envelopes and the database is evaluated using the correlation between their first derivatives, which removes the baseline slope and clarifies the spectral features: see Figures 2(c) and (d). The appropriate frequency range over which to calculate the correlation coefficients depends on the powder's particle size and the condition of the package. The range is determined on the basis of the spectrum's absorption intensity. A list of possible materials is displayed based on the correlation coefficient.
Procedures for spectral analysis and database retrieval are executed automatically and no special knowledge is necessary to operate the system. The prototype is now installed in Japanese post offices, and our current research focuses on evaluating the system's performance and its limits.

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Hiromichi Hoshina, Yoshiakim Sasaki, Aya Hayashi, Chiko Otani

Terahertz Sensing and Imaging Laboratory

RIKEN

Sendai, Japan

http://www.riken.jp/lab-www/THz-img/English/index.htm  

Hiromichi Hoshina received his PhD from Kyoto University in 2003. His current research focuses on developing spectroscopic applications using THz waves.
Yoshiaki Sasaki received his PhD from Yamagata University in 2004. His current research interests include the detection of scattered THz waves from powders, THz imaging, and THz heterodyne detection.
Aya Hayashi received her MSc from Meiji University in 2002. Her research is in bioimaging of cancer and DNA using THz waves.
Chiko Otani received his PhD in astronomy from the University of Tokyo in 1995 and is now head of the Terahertz Sensing and Imaging Laboratory. His research interests include superconducting THz detectors and their applications.

Koko Kawase

Optical Quantum Engineering Group

Nagoya University

Nagoya, Japan

http://www.nuee.nagoya-u.ac.jp/labs/optlab/kawase/

Kodo Kawase received his PhD in electronic engineering from Tohoku University in 1996. A professor in the Graduate School of Engineering (since 2005), he has been involved in research on THz-wave generation using nonlinear optics since 1992.

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References:

1. K. Kawase, Y. Ogawa, Y. Watanabe, Non-destructive terahertz imaging of illicit drugs using spectral fingerprints, Opt. Express 11, pp. 2549-2554, 2003.

2. T. Ikeda, A. Matsushita, M. Tatsuno, Y. Minami, M. Yamaguchi, K. Yamamoto, M. Tani, M. Hangyo, Investigation of inflammable liquids by terahertz spectroscopy, Appl. Phys. Lett. 87, pp. 034105, 2005.  doi:10.1063/1.199847

3. J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, D. Zimdars, THz imaging and sensing for security applications-explosives, weapons and drugs, Semicond. Sci. Technol. 20, pp. S266-S280, 2005.  doi:10.1088/0268-1242/20/7/018

4. H.-B. Liu, H. Zhong, N. Karpowicz, Y. Chen, X.-C. Zhang, Terahertz spectroscopy and imaging for defence and security applications, Proc. IEEE 95, pp. 1514-1527, 2007.

5. H. C. van de Hulst, Light Scattering by Small Particles, Dover Publications Inc., New York, 1981. 

http://spie.org/x33690.xml?ArticleID=x33690

Scientists in Singapore and Japan team up to push frontiers in materials design and nano-optical techniques

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FOR SOME REASON, I NEVER POSTED THIS STORY WHEN IT CAME OVER THE WEB, LAST MARCH. PERHAPS ONE REASON, IS MY INTRODUCTORY QUESTION. OBVIOUSLY, I HAVE NO REAL EXPERTISE IN THIS AREA, SO PLEASE EXCUSE THE QUESTION, OR BETTER YET PLEASE HELP ME OUT HERE BY POSTING A COMMENT. SOME OF YOU WILL NOTICE THAT I HAVE ADDED A WORLD MAP WHICH SHOWS WHERE WE ARE GETTING VISITORS TO THIS BLOG FROM. SINCE JUNE OF THIS YEAR, GOOGLE HAS KEPT A STATS PAGE, WHICH IS VERY INTERESTING. SINCE JUNE, THE BLOG HAS HAD 699 US VISITORS, 167 CANADIAN, 117 UK, 56 GERMANY, 49 INDIA, 41 RUSSIA, 31 JAPAN, 24 TAIWAN, 20 ITALY, 13 FRANCE. THE COMPANION GROUP PAGE IS GETTING THOUSANDS OF VISITS EACH WEEK. 3050 LAST WEEK ALONE.
SO SOMEBODY BESIDES ME IS INTERESTED IN TERAHERTZ TECHNOLOGY. WHY ISN'T ANYONE POSTING? PLEASE EMAIL ME AND LET ME KNOW IF THERE IS A PROBLEM PLACING A COMMENT HERE.
ONE OTHER CHANGE, IS THAT I HAVE TAKEN THE "PLUNGE", AND WILL ALLOW AD-SENSE TO POST RELEVANT ADS. IT'S JUST A TEST RUN, TO SEE HOW IT WORKS OUT. SOME OF YOU WHO HAVE TECHNICAL KNOWLEDGE PLEASE HELP ME OUT HERE, BY POSTING!




(My note: Research is moving along throughout the world on the development of terahertz. This article points out an apparent weakness in existing systems that I was unaware of. The authors write: "...current THz frequency-domain spectroscopy (THz-FDS) techniques are suitable only for isotropic samples. Yet, most test materials are birefringent and can result in polarization-dependent loss (PDL). Therefore, current THz-FDS systems may not explain fully the test results." An obvious question, is whether frequency-domain THz is the same as time-domain Thz.)




(Nanowerk News) Three teams of researchers, each jointly led by a Singaporean and a Japanese, have been awarded a total of $2m in research grants by Singapore’s Agency for Science, Technology and Research (A*STAR) and the Japan Science and Technology Agency (JST) under the Strategic International Cooperative Programme (SICP). These projects are in the fields of “Physical Materials and Devices” and “Photonics and Nano-Optics” – research areas previously identified as strategic areas of co-operation.
The three collaborative research projects, which have been selected from 11 high quality applications after a thorough process of independent external reviews conducted by A*STAR and JST, are as follows:
1024x1024 Optical Crossconnect for terabit/s routers and supercomputers. This project is jointly led by Dr Yeo Yong-Kee from A*STAR’s Institute for Infocomm Research (I2R) and Dr Tetsuya Kawanishi from the New Generation Network Research Center, National Institute of Information and Communications Technology, Japan.
With the rapid expansion of the Internet, the demand for high-capacity electronic network routers is expected to grow exponentially. However, higher capacity corresponds with with higher heat dissipation and power consumption. A high-end terabit/s router today consumes up to 10kW of power, and this is expected to grow to 50kW within the decade if routers do not evolve.
By replacing electronic switches in these routers with an optical version, the team aims to revolutionalise the routers’ architectural design. Utilizing advanced switching components, such as those based on quantum-dot optical devices, they aim to develop a router switch with at least forty times the capacity of what is currently available while consuming the same amount of power or less.
Investigation on a polarimetric terahertz (THz) frequency domain spectroscopy system. This is led jointly by Dr Gong Yandong from A*STAR’s Institute for Infocomm research (I2R) and Dr Hiroaki Minamide from Advanced Science Institute (Sendai), RIKEN.
The electromagnetic wave in the THz band (100GHz –10THz) has become increasingly important in applied and basic research, with its ability to image and measure samples which are opaque in the visible and near-infrared regions of the spectrum.
However, current THz frequency-domain spectroscopy (THz-FDS) techniques are suitable only for isotropic samples. Yet, most test materials are birefringent and can result in polarization-dependent loss (PDL). Therefore, current THz-FDS systems may not explain fully the test results.
By tackling these polarization topics, the team aims to improve the accuracy of imaging and measurements in such polarimetric THz-FDS systems by incorporating various polarization information.
Ultrafast transient absorption techniques to study charge generation dynamics for holistic OPV materials and devices characterization from charge generation to collection. This is led by Dr Gorelik Sergey from A*STAR’s Institute of Materials Research and Engineering (IMRE) and Dr Ryuzi Katoh from the National Institute of Advanced Industrial Science and Technology (AIST).
Organic photovoltaic (OPV) devices are the key to the harvesting of solar energy, as they can be manufactured via solution-based methods, which drive down costs greatly. Photocurrent generation in OPV devices involves three basic stages: exciton formation; charge separation; and charge transport and collection. To develop new OPV materials for more efficient devices, it is essential to understand the physics involved in each stage.
The team aims to develop an overall characterisation of new OPV materials, currently being designed in-house in IMRE. By combining infrastructure and expertise from both IMRE and AIST to independently assess each of the processes, and correlating the findings with overall device performance, this project will reveal answers to the design of more efficient OPV systems.
Said Professor Low Teck Seng, Deputy Managing Director (Research), A*STAR and Executive Director, Science and Engineering Research Council, A*STAR, “The projects are of an exceptional standard. Each project team has demonstrated a high ability to innovate and challenge paradigms, as well as a high level of scientific pursuit. I am confident that collaborations such as these will not only push the frontiers of science, but will also go a long way in building closer ties between researchers from the two countries and in facilitating greater interactions which will spawn new and fascinating ideas and innovations to contribute to society and the world.”
SICP aims to promote research collaborations and exchanges between Singaporean and Japanese researchers by providing funding for joint research projects and workshops in the two countries. A*STAR and JST have mutually agreed to support research within the field of “Functional Applications in Physical Sciences”, which encompasses strategic research areas such as Nanotechnology, Materials including applications for photonics and terahertz, and Chemistry including nanobiotechnology and bioelectronics.
SICP, which was started in 2003, has been promoted by JST to foster active research exchange through supporting researchers from Japan and 22 countries and areas in Europe, America, Pacific, Asia, Middle East and Africa under this framework.