The Earth-Life Science Institute (ELSI) was launched on

December 7, 2012 after being selected by the Ministry of

Education, Culture, Sports, Science and Technology (MEXT) to

participate in its World Premier International Research Center

Initiative (WPI). This initiative re�ects the Japanese government’s

e�ort to build globally outstanding science research centers in

Japan.

To celebrate the launch, an opening ceremony was held

on March 27, 2013 in Kuramae Hall at Tokyo Institute of

Technology’s Ookayama campus, followed by ELSI’s 1st

International Symposium.

Tokyo Tech’s president Yoshinao Mishima opened the three-

day event with his speech con�rming the university’s strong

commitment to support ELSI’s director Kei Hirose in building

a �rst-rate international and dynamic institute. Following his

talk were congratulatory speeches by honorable guests and

collaborators from organizations involved in ELSI’s support

and success, such as MEXT; Japan Society for the Promotion

of Sciences (JSPS); Masuo Aizawa, the former president of

Tokyo Tech; Ehime University, Japan Aerospace Exploration

Agency (JAXA) and Japan Agency for Marine-Earth Science and

Technology (JAMSTEC), all of whom are satellite institutes to

ELSI.

The ceremony closed with two talks, one by Piet Hut, associate

director of ELSI overseeing its international and interdisciplinary

research a�airs, and the grand �nale speech by director Kei

Hirose who outlined ELSI’s dual mission of studying the “origin

and evolution of life” and the “origin and evolution of the Earth”

through the interdisciplinary collaboration between the �elds

of Earth, planetary, and life sciences.

ELSI’s 1st International Symposium began with a venue change

to Digital Hall. Topics from Solid-Earth Science, Planetary

Science, Geology, Environmental Biology, Microbial Genome

Science, and other related �elds to ELSI’s research scope were

presented, debated and discussed by its Principal Investigators

and invited researchers from various institutions from abroad

and Japan.

As ELSI’s �rst symposium, the lectures were left to be of a broad

focus, to gain insight into the status and trends of research

in the various disciplines. The symposium was a success in

bringing forth an active and meaningful interdisciplinary

exchange by top-notch researchers linked by ELSI’s objective, of

approaching the origin and evolution of life question by �rmly

situating the research in the early Earth context that allowed for

the rise of initial life and its subsequent evolution to complexity.

Earth-Life Science Institute’s OpeningCeremony & 1st International Symposium

InternationalWINTER 2013VOL.18

Tokyo Institute of Technology Newsletter

Tokyo Tech

01 NewsEarth-Life Science Institute’s Opening Ceremony & 1st International Symposium

ASCENT 2013 - Indonesian, Thai and Japanese students study Robot-related Technology

"Science and Engineering Communication Project" launched this summer

02 Innovators and InnovationsRemoving radioactive cesium following Fukushima

03 Recent ResearchBiopolymers: Long polyester synthesized by E. coli

Advances in mathematics: Solution to a problem in the nineteenth century theory of meromorphic functions

Evacuation procedures in big cities after massive earthquakes: Models based on the behavior of people in Tokyo after the Tohoku-Paci�c Ocean Earthquake on 11 March 2011

04 FeatureLow temperature physics on a jet-plane

05 Partner Universities Letter from Republika Slovenija

06 Through Student Eyes"Uniting in Norway: What I learnt and my future plans

07 TopicsComing round to stable self-assembly

C O N T E N T S

News01

ELSI’s 1st International Symposium heldat the Digital Hall in Ookayama Campus

Director of ELSI, Professor Kei Hirose The Opening ceremony of the Earth-Life Science Institute (ELSI)

This summer Tokyo Tech launched a new, trial TIER Summer Program

class, the Science and Engineering Communication Project (SECP), for TiROP

and CAMPUS Asia summer program participants. The goal of the class

was twofold: simulate international collaboration that might be found

in a laboratory at a leading global university or research institution

and allow students to develop team and leadership skills necessary for

working in the global environment.

SECP is grounded in the learner-centered style of teaching where the

instructor facilitates and students take an active role in their knowledge

acquisition. When a student or scholar goes abroad to study or

conduct research, he or she steps into a di�erent culture and has to

communicate and work with people with di�erent ideas and di�erent

cultural assumptions to achieve common goals. Communication

skills, negotiation skills and leadership skills are important in such

circumstances and these are very di�cult to teach in a typical teacher-

SAGE (Student Association for Global Exchange) organized ASCENT

2013 in March, 2013. ASCENT (Asian Students Collaboration

Encouragement Program in Technology) started in 2010, and is a

study program held in Japan that contains special lectures from

professors, company visits, and laboratory visits at Tokyo Tech. It o�ers

opportunities for students from Thailand, Indonesia and Japan to learn

about di�erent aspects of Japanese technology and to make friends

with those from other Asian countries.

The theme of ASCENT 2013 was “Robot-related Technology”. This

year there were two participants from Japan, two from Thailand

(Chulalongkorn University) and �ve from Indonesia (Institute of

Technology Bandung). All contents of this program are planned and

coordinated by the student members of SAGE.

In order to get introductory knowledge about robot technology, two

professors from Tokyo Tech provided lectures to the students. The

group also had opportunities to see advanced robots and receive

lectures from specialists at Hitachi, Ltd., in Hitachi, Ibaraki prefecture,

and The National Institute for Advanced Industrial Science and

Technology (AIST), located in

Tsukuba.

In the middle of the program,

Professor Tom Hope of the

University Management Center

at Tokyo Tech provided a lecture

on improving presentation skills.

The participants then created a mid-term presentation containing

information they had learned from the company and research institute

visit.

During the subsequent visits of laboratories in Tokyo Tech, members

of each laboratory gave information related to new robot technology

through videos and demonstrations.

After visiting the company, institute and laboratories the participants

were divided into three groups and made a �nal presentation to

summarize ASCENT 2013. They decided the topics to focus on

associated with original theme of this year’s program. Participants

eagerly discussed their own topic. The presentations were successfully

given, receiving comments by Professor Akinori Nishihara from Tokyo

Tech’s Department of Human System Science.

ASCENT2013 ended with students receiving a certi�cation of

participation, and a gift from Indonesia and Thailand. SAGE member

Soichiro Endo had the following to add: “Our student organization is

still small but we are trying to make this program bigger. We hope that

ASCENT will successfully continue in the future.”

ASCENT 2013 - Indonesian, Thai and Japanese students study Robot-related Technology

�Science and Engineering Communication Project” launched this summer

News01

Explanation about EMIEW 2 at Hitachi Ltd.

Explanation about M-TRAN at AIST An opportunity for a picture in front of AIST with other Tokyo Tech members

Group work on July 3 The durability test on July 24

Explanation about research in Kurabayashi Lab., Tokyo Tech

2 Tokyo Tech International WINTER 2013 VOL.18

centered or top-down learning environment.

SECP was designed to meet these needs in our increasingly

interconnected and collaborative world. As this year’s theme, “Making

a Straw Bridge” was selected for the group project around which the

students would develop their ideas and strategies for both construction

of the bridge and communication. Not only would the groups of

international students from 8 countries have to communicate with

each other to design a bridge, but they would have to communicate

how to build it to visiting Japanese high school students who would

then construct it. Three “Bridge Policies” were set and the six groups

of international and Tokyo Tech students welcomed 4-5 high school

students into their groups and taught them in English how to construct

the bridge they designed. All of the students enjoyed themselves

immensely as they competed for points in the areas of “Our Cost E�ective

Bridge”, “Most Aesthetically Pleasing Bridge” and “Most Durable Bridge.”

The course had four formal weekly meetings starting on July 3 and

�nishing on July 24 with the competition and outreach in English to 26

local high school students. The high school students enjoyed a campus

tour of Tokyo Tech in the morning and then joined one of the six groups

as described above for an afternoon of fun and hands-on activities.

Feedback from the international students has been very positive,

represented by this comment: “I had a great time communicating with

the International as well as Japanese students.”

Removing radioactive cesium following Fukushima

A new decontamination process developed at Tokyo Tech may prove vital

in the removal of radioactive cesium from the land around Fukushima

Current decontamination methods for removing radioactive nuclides

from the environment are not e�ective enough to cope with the scale

of the Fukushima Daiichi nuclear disaster. Following calls for new

research, Kenji Takeshita and Hideharu Takahashi at Tokyo Institute of

Technology, together with scientists and engineers at CDM Consulting

and the Radwaste and Decommissioning Center (RANDEC), have

developed a novel methodology for the e�ective and e�cient removal

of radioactive cesium from soils and sewage sludge.1,2

Takeshita’s team combined two techniques – a hydrothermal process

followed by so-called coagulation settling (Fig.1). Firstly, they added

water to contaminated solids and heated the solution to 200°C-260°C

whilst stirring in a closed container. The organic materials in the solids

began to decompose under hydrothermal conditions attained by the

rising heat and pressure. Next, the remained solid material was washed,

small amounts of inorganic coagulant and adsorbant powders (Ferric

Ferrocyanide) added and the cesium removed as a precipitate. In this

way, the researchers successfully removed 96% of cesium from sewage

sludge sampled in Fukushima city.

Removing contaminants from soils proved more di�cult. The team

extended the process to include ‘blasting’ - releasing the pressure

in the hydrothermic solution suddenly by opening a valve, further

fragmenting the decomposing solids. By blasting the solution twice,

followed by coagulation settling, over 90% of cesium was removed

from the soils.

The new process is highly e�ective and leaves little secondary waste,

and the team are hopeful it will help in the decontamination of

Fukushima.

Reference:1. K. Takeshita, H. Takahashi, Y. Jinbo & A. Ishido. Restoration of water environment contaminated by radioactive cesium released from Fukushima Daiichi NPP. Proceedings of GLOBAL 2013, Salt Lake City, 2013.2. News Focus, ‘Cooling a Hot Zone’, Science 339, 1028-1029DOI: 10.1126/science.339.6123.1028http://www.sciencemag.org/content/339/6123/1028.full

Fig. 1: Tokyo Tech scientists and co-workers have developed a new combined methodology for removing radioactive cesium from soil and sewage sludge using hydrothermal and coagulant settling processes.

Innovators andInnovations02

High school students constructing a bridge according to SECP blueprints

3Tokyo Tech International WINTER 2013 VOL.18

Ultrahigh-molecular-weight polyhydroxybutyrate (UHMW-PHB,

Mw>3,000,000) synthesized by genetically engineered Escherichia

coli is an environmentally friendly bioplastic material which can be

processed into strong �lms or �bers.

However, the e�cient production of UHMW-PHB is proving to be

technologically challenging.

Here, Takeharu Tsuge and colleagues at Tokyo Institute of

Technology, Keio University, and State University of New York have

shown that rearrangement of gene order in the PHB biosynthesis

operon (phaCAB) is an e�ective method for producing UHMW-PHB

in E. coli.

The three genes of the phaCAB operon are phaC, which encodes

PHB synthase, phaA and phaB, which encode monomer-supplying

enzymes. The researchers examined the e�ect of gene order of

the phaCAB operon (phaABC, phaACB, phaBAC, phaBCA, phaCAB,

and phaCBA) in order to determine the best organization for the

production of UHMW-PHB.

Experimental results showed that the molecular weights and

production levels of PHB were both dependent on the order of

the relatives of the pha genes to the promoter. The most balanced

production result was achieved using the phaBCA order.

This �nding is an important contribution for the construction

a highly e�cient UHMW-PHB system for producing for this

commercially important polymer.

Biopolymers: Long polyester synthesized by E. coli

Reference: · Authors: Ayaka Hiroe, Kenji Tsuge, Christopher T. Nomura, Mitsuhiro Itaya, and Takeharu Tsuge.· Title of original paper: Rearrangement of gene order in the phaCAB operon leads to effective production of ultrahigh-molecular-weight poly[(R)-3-hydroxybutyrate] in genetically engineered Escherichia coli. · Journal, volume, pages and year: Applied and Environmental Microbiology 78, 3177 (2012). · Digital Object Identifier (DOI): 10.1128/AEM.07715-11· Affiliations: Department of Innovative and Engineered Materials, Tokyo Institute of Technology; Institute for Advanced Biosciences, Keio University; and Department of Chemistry, State University of New York College of Environmental Science and Forestry. · Department website:http://www.iem.titech.ac.jp/tsuge/english.html

Increase in PHB molecular weight due to gene rearrangement.

Recent Research03

Gene rearrangement of PHB biosynthesis genes.

Production and application of PHB.

4 Tokyo Tech International WINTER 2013 VOL.18

The Tohoku-Paci�c Ocean Earthquake occurred on 11 May 2011. On

this day all rail services in the Tokyo Metropolitan area were paralyzed

amid the unprecedented confusion that followed the tremor.

Thousands people were unable to contact families and friends, and

in a state of uneasiness, many decided to return home on foot. Main

roads were heavily congested with both cars and people, a state which

severely obstructed the movement of emergency vehicles.

Here, Toshihiro Osaragi at Tokyo Institute of Technology describes the

construction of several models that describe decision-making and

behavior of individuals attempting to reach home on foot in the wake

of a devastating earthquake.

He has simulated the movement of individuals who have decided

to return home on foot, and demonstrates the spatiotemporal

distribution of those who might be exposed to hazardous city �res on

their way home in the aftermath of a massive earthquake, which has

been predicted to occur in the Tokyo Metropolitan area in near future.

Osaragi research underscores the importance of considering

pedestrian �ow under such extreme scenarios in order to establish

emergency evacuation procedures. “Using the model proposed, we

can assess not only the potential number of stranded individuals, but

also their detailed attributes,” says Osaragi. “Such information would

undoubtedly prove helpful in actual planning for immediate post-

disaster mitigation.”

Reference:· Authors: Toshihiro Osaragi. · Title of original paper: Modeling a spatiotemporal distribution of stranded people returning home on foot in the aftermath of a large-scale earthquake. · Journal, volume, pages and year: Natural Hazards, Springer, (2012). · Digital Object Identifier (DOI): 10.1007/s11069-012-0175-8 · Affiliations: Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology.· Department website: osaragi@mei.titech.ac.jp

Evacuation procedures in big cities after massive earthquakes: Models based on the behavior of people in Tokyo after the Tohoku-Paci�c Ocean Earthquake on 11 March 2011

General theory of meromorphic functions in the complex plane began

in the nineteenth century, when E. Picard proved his famous ‘Picard’s

little theorem’. Then, in the 1920s, R. Nevanlinna created the modern

theory of meromorphic functions, where his ‘second main theorem

(SMT)’ provides a far-reaching generalization of Picard’s theorem.

Nowadays, the theory is well-established as a result of many excellent

research studies. Nevertheless, the theory still has several unresolved

problems, including the following one:

Conjecture of Gol’dberg, middle 1980-s: For every transcendental

meromorphic function in the plane, the frequency of distinct poles is

governed by the frequency of zeros of the second derivative.

Now, Tokyo Tech mathematician Katsutoshi Yamanoi has solved this

conjecture.

The solution is based on two important developments in Nevanlinna

theory, which are interesting for their own sake. The �rst one is a

generalization of SMT for small moving targets. The other is a reversion

of SMT.

The proof shows that Gol’dberg’s conjecture is true in more general

form. The results described by Yamanoi in this paper are an important

breakthrough in the theory of meromorphic functions.

Reference:Author: Katsutoshi YamanoiTitle of original paper: Zeros of higher derivatives of meromorphic functions in the complex planeJournal, volume, pages and year: Proc. London Math. Soc. (2012), 78 pages.Digital Object Identifier (DOI): 10.1112/plms/pds051Affiliations: Department of Mathematics, Tokyo Institute of TechnologyDepartment website: http://www.math.titech.ac.jp

Fig. 1. The statement of Gol’dberg conjecture from the original paper.

Advances in mathematics: Solution to a problem in the nineteenth century theory of meromorphic functions

Risk of �re and spatiotemporal distribution of stranded people after the earthquake.

5Tokyo Tech International WINTER 2013 VOL.18

Feature04

Yuichi Okuda describes his group’s research on microgravity

experiments in aircraft �ying parabolic trajectories to shed light on the

true nature of the crystallization of helium at ultra-low temperatures

“My group is investigating the crystal growth of helium-4 (He-

4) and helium-3 at ultra-low temperatures,” says Yuichi Okuda.

“Observing the crystallization behavior of helium at milli-Kelvin

gives tremendous insight into the physics of so-called quantum

solids and resulting phenomena including super�uidity.”

However, in spite of the major advances in research on the

low temperature crystalline properties of helium there are still

fundamental unaddressed questions. “All our experiments to date

have been conducted under the in�uence gravity,” explains Okuda.

“One of the important unexplored areas in the research is the

e�ect of gravity on the crystallization dynamics of helium. That is,

we want to know the true nature of helium-4 crystallization at low

temperatures and under zero gravity.”

Designing experiments to optically monitor crystallization

dynamics of He-4 under zero gravity is challenging. Meeting this

challenge, Okuda and colleagues constructed a unique experiment

system consisting of a cryostat for cooling the He-4 to sub-Kelvin

temperatures and peripheral video monitoring equipment,

for installation in a small jet plane. “The plane containing the

experimental equipment and researchers, took o� and went

through a series of parabolic dives, which produced an environment

of less than 0.01 G for about 20 seconds,” says Okuda. “We regard

this as being almost zero gravity for these experiments.”

The aircraft produced about 8 parabolic maneuvers per �ight,

during which time the crystallization dynamics of He-4 were

observed using video cameras. Needless to say, compared with low

temperature experiments conducted on the ground, the limited

space and movement of the ‘MU300’ jet plane lead to restrictions

in the design of the apparatus: Total weight of equipment ~300 kg;

power lines of ac 100 V (1 kVA and 1.5 kVA) and two dc of 28 V (0.7

kVA); equipment was housed inside three racks measuring 900 (h)

mm x 700 (l) mm x 450 (w) mm. The system enabled the realization

of a temperature of 0.62 K for a period of approximately 7 hours.

The main �ndings of the experiments during the parabolic �ights

were (1) The ‘bcc’ structure of He-4 did not change over a period of

20 seconds at the relatively high temperature of 1.6 K due to its low

crystallization rate. (2) At 0.63K the ‘hcp’ phease of He-4 changed to

where the “c-facet became larger and the a-facet emerged on the

surface”, notes Okuda.

Notably, the crystals remained attached to the wall of the sample

holder due to adhesive forces resulting from interaction with the

walls. “In more recent experiments we used acoustic vibrations to

dislodge the He-4 crystals from the walls,” says Okuda. “Intriguingly,

we discovered so-called Ostwald ripening of these crystals after

exposure to acoustic waves, where smaller crystals melt and larger

ones grow to minimize the surface energy.”

These unique set of experiments not only shed light on the

fascinating �eld of quantum solids but also open the door to a new

�eld of low temperature physics at zero gravity.

Further information-Okuda Group: http://www.ltp.ap.titech.ac.jp/eng/member.html-Development of a 3He Refrigerator for Possible Experiments of Solid He-4 on a Small Jet Plane, J Low Temp Phys (2011) 162: 733–739-He-4 crystals in superfluid under zero gravity, Physical Review E 85, 030601(R) (2012)-Ripening of splashed 4He crystals by acoustic waves with and without gravity, New Journal of Physics 14 (2012) 123023

Shape of a relatively large 4He crystal in the hcp phase at T = 0.63 K. Gravity values are speci�ed in each frame. The horizontal line in the right picture is the rough surface under 1 G, and the inclined line is c facet. The crystal responded to the gravity change and c facet expandedunder reduced gravity (in the left picture).A facet is also apparent on the sides of the crystal. The diameter of the �eld of view (circular visible region) was 24 mm.

Time evolution of 4He crystals which splashed into super�uid at zero gravity initially at 0.67 K. Ostwald ripening continued to the end and only the largest crystal survived at the cost of smaller ones.The photograph on the extreme right shows crystals after only 3 seconds has elapsed from the splashing.

Ready for takeo� for parabolic �ight based experiments. The equipment on the right hand side is the compressor and controller for producing sub-kelvin temperatures.

Ready for boarding. Professor Yuichi Okuda is second from right.

The experimental conditions on board the airplane.

Low temperature physics on a jet-plane

Tokyo Tech International WINTER 2013 VOL.186

"Uniting in Norway: What I learnt and my future plansTakumi Ninomiya, a master’s student studying Industrial Engineering and

Management, recently returned from his study abroad in Norway. Here he

explains about his experiences in Norway and the effect it has made on his

plans for the future after Tokyo Tech.

I have never lived abroad before. I thought that there will still be many

things that I do not know in the world if I just stay in Japan. I was curious

about that and I wanted to see with my own eyes. This is why I decided to

study in Norway. Additionally, the university I studied at is really famous

as an international university, so I could interact with a lot of people from

various kinds of countries. As a result, I could experience a lot of new

things: cultural di�erences, living alone in a foreign country and so on.

Actually, Some Japanese people do not have a good image of Korean

and Chinese people primarily because of information on the internet.

However, after I got many friends from those countries, I found that those

images are wrong. All of my friends from those countries were really nice

to me. Of course, I found some cultural di�erences, but they were almost

the same as we Japanese. I could know the “truth” about them. I think

“studying (for example Mathematics)” itself is an important thing but

studying these kind of things are also important.

Norway is very famous country for its nature like �ords. In addition to

studying, I could enjoy really beautiful scenery which cannot be seen in

Japan. And I could watch Northern light also. It can be seen only in some

parts of the earth so I was very lucky.

My dream so far is to work for a Japanese company because I think they

need Japanese people who have an international perspective. I want to

make the best use of my experience for improving Japanese society. But

still, I want to be sure to use English after I start work, so I am also applying

for some foreign funds in Japan for internship opportunities.

ThroughStudent Eyes

I was the �rst PhD student at

Tokyo Institute of Technology

coming from the Faculty of

Arts, University of Ljubljana,

the major university in

Slovenia. I studied at the

Department of Human

System Science, Graduate

School of Decision Sciences

and Technology, under the

supervision of Prof. Kikuko

Nishina. During that period I greatly appreciated the opportunity to

join various large-scale research projects, experience science-café

meetings and cooperate with people of various research �elds.

Thanks to a fruitful collaboration between Prof. Andrej Bekes

from the University of Ljubljana and Prof. Nishina Kikuko, the �rst

agreement for cooperation between our universities, Tokyo Tech's

International Student Center and the University of Ljubljana's

Faculty of Arts, was created in 2007.

Since that time a number of short and long-term visits of professors

from both universities have taken place, which contributed to

sharing and widening research expertise especially in relation to

Japanese language didactics and successful implementation of

theoretical linguistic frameworks into practical computer-assisted

language education.

We have just extended the cooperation agreement between the

universities, coordinated on the Japanese side by Prof. Naoki Takei

from Tokyo Tech's International Student Center. Within a bilateral

project of cooperation between Slovenia and Japan, lead by Prof.

Chikako Shigemori Bucar from the University of Ljubljana, a number

of teachers from our university visited Tokyo Tech to discuss

broadening further cooperation.

The University of Ljubljana has mutual agreements with various

universities in Europe, Japan and beyond. The study programs,

including Japanese studies and programs at various technical and

natural sciences faculties, have double majors and joint degrees,

which allows for extensive interdisciplinary integration. Therefore

we intend to widen and foster our relations with Tokyo Tech to

further increase the mobility of students and teachers at both

universities including various faculties and disciplines.

The 14th International Conference of EAJS (European Association

for Japanese Studies) will be held at the University of Ljubljana on

August 27-30th 2014, and we look forward to hosting researchers

from Tokyo Tech, Japan, and all over the world.

Related informationFaculty of Arts, University of Ljubljanahttp://www.ff.uni-lj.si/National Institute for Japanese Languagehttp://www.ninjal.ac.jp/english/14th International Conference of EAJS: http://www.eajs.eu/?id=305

Letter from Republika Slovenija

Dr. I rena Srdanovic

Assistant Professor of Japanese Studies at the Faculty of Arts, University of Ljubljana (Slovenia) / Visiting Researcher at the National Institute for Japanese Language (Oct 2012 - Oct 2013)

Luckily, I could see the northern lights with my Korean friends!

Climb up to the “Preikestolen” in the Lyse�orden (the guy who is raising his arms is me.)

Doing “v sign” which is common for Asian people but not for people from many other countries

Green surroundings of the Faculty of Arts

City of Ljubljana, where the majority of the University of Ljubljana’s faculties are located

Japanese and Slovene students in one of the exchange programs - traditional music moments

05

06

Partner Universities

Research cooperation & cherry blossoms at Tokyo Tech (from right: Prof. Bekes, Prof. Nishina, Dr. Srdanovic, PhD candidate Hodoscek)

7Tokyo Tech International WINTER 2013 VOL.18

Scientists at Tokyo Tech have

developed a new self-assembled

nanostructure that can survive

very hot or saline environments

Nanostructures that assemble

themselves from polymer

molecules could prove to be

useful tools in chemistry and industry. However, it is di�cult to

develop structurally robust self-assembling materials because they

are often adversely a�ected by their surroundings.

Many natural organisms have evolved to protect themselves in

hostile environments. For example, types of archaea - single-cell

microorganisms living in hot springs - have cyclic molecules in

their cell membranes that form shields to preserve the cell under

extreme heat.

Inspired by nature’s use of cyclic structures, Takuya Yamamoto and co-

workers at the Department of Organic and Polymeric Materials, Tokyo

Institute of Technology, have dramatically enhanced both the thermal

and salt stability of self-assembling polymeric structures, simply by

changing the shape of the founding polymers from linear to cyclic.

The team designed new block copolymers - structures comprising

several polymers connected by covalent bonding - which self-

assembled into shapes called micelles (Fig.1). Micelles have a

hydrophilic (water-attracting) outer membrane, and a hydrophobic

(water-repelling) core.

“We designed a cyclic amphiphilic block copolymer by mimicking

fat molecules in the cell membrane of archaea,” explains Yamamoto.

“Both linear and cyclic copolymers were then used to create

identical self-assembling �ower-shaped micelles.” The team

discovered that although the chemical composition, concentration

and dimensions of micelles built from the two di�erently shaped

block copolymers remained the same, the cyclic-based micelles

were able to withstand higher temperatures.

“The micelle from cyclic block copolymers withstood temperatures

up to 40°C higher than the linear-based micelles,” explains

Yamamoto. The researchers found that the tail ends of the linear

copolymers were more likely to break loose from the �ower-shaped

structure during heating, allowing for bridging between micelles to

occur. This meant that the micelles join together in an agglomerate

blob at a relatively low temperature. The micelles created by the

cyclical copolymers, on the other hand, had no ‘loose ends’ to form

bridges, meaning the structures remained stable up to far higher

temperatures.

The same structural di�erences allow for a greater tolerance of salt

concentrations in the cyclic-based micelles. The loose tails in linear-

based micelles allowed rapid dehydration to occur in highly saline

environments, whereas the closed cyclic structures are structurally

stronger, making them more resilient to salt.

“The combination of higher salting-out concentrations and

thermal resistance means these micelles have numerous potential

applications,” explains Yamamoto. “Possibilities include drug

delivery systems, where heating is not possible and salt provides

an alternative method for controlling how a micelle responds in

order to release a drug.” The team also hope that their micelles

could provide the basis for many new materials in the �eld of green

chemistry, because their structural robustness is based purely on

their shape rather than on complex chemical reactions.

Reference: 1 S. Honda et al. Topology-directed control on thermal stability: micelles formed from linear and cyclized amphiphilic block copolymers. JACS Communications, published online July 2010. 2 S. Honda et al. Tuneable enhancement of the salt and thermal stability of polymeric micelles by cyclized amphiphiles. Nature Communications 4, Mar 2013.

Coming round to stable self-assembly

Inquiries about this publicationCenter for Public InformationE-mail: pr@jim.titech.ac.jp

Admissions informationhttp://www.titech.ac.jp/english/graduate_school/international/index.html

Tokyo Tech o�cial facebook pagehttp://www.facebook.com/tokyotech.en

PublisherKiyoshi Otani, Director, Center for Public Information

Editorial committeeChairman: Tom Hope, University Management CenterKayoko Nohara, International Student Center

Technical supportTakashi Yatomi, Miwako Kato, Sayuri Sato, Satoshi Nishida, Yuya Takao, Yukiko TokidaCenter for Public Information

Topics07

"Tokyo Tech International" is an o�cial publication of Tokyo Institute of Technology published by the university’s Center for Public Information.2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan. Tel: +81-3-5734-2975 Fax: +81-3-5734-3661

©2013 Tokyo Institute of Technology

Takuya Yamamoto

Fig. 1 The team used linear and cyclic block copolymers to create �ower-shapedmicelles. The cyclic-based micelles withstood considerably higher temperaturesand salinity levels, and could have numerous applications in industry and green chemistry.