Entity

Time filter

Source Type


Sugiyama T.,Instrument Technology Research Center | Yuyama K.-I.,National Chiao Tung University | Masuhara H.,National Chiao Tung University
Accounts of Chemical Research | Year: 2012

Laser trapping has served as a useful tool in physics and biology, but, before our work, chemists had not paid much attention to this technique because molecules are too small to be trapped in solution at room temperature. In late 1980s, we demonstrated laser trapping of micrometer-sized particles, developed various methodologies for their manipulation, ablation, and patterning in solution, and elucidated their dynamics and mechanism. In the 1990s, we started laser trapping studies on polymers, micelles, dendrimers, and gold, as well as polymer nanoparticles. Many groups also reported laser trapping studies of nanoclusters, DNA, colloidal suspensions, etc. Following these research streams, we have explored new molecular phenomena induced by laser trapping. Gradient force leading to trapping, mass transfer by local heating, and molecular reorientation following laser polarization are intimately coupled with molecular cluster and aggregate formation due to their intermolecular interactions, which depend on whether the trapping position is at the interface/surface or in solution.In this Account, we summarize our systematic studies on laser trapping chemistry and present some new advances and our future perspectives. We describe the laser trapping of nanoparticles, polymers, and amino acid clusters in solution by focusing a continuous wave 1064 nm laser beam on the molecules of interest and consider their dynamics and mechanism. In dilute solution, nanoparticles with weak mutual interactions are individually trapped at the focal point, while laser trapping of nanoparticles in concentrated solution assembles and confines numerous particles at the focal spot. The assembly of polymers during their laser trapping extends out from the focal point because of the interpolymer interactions, heat transfer, and solvent flow. When the trapping laser is focused at an interface between a thin heavy water solution film of glycine and a glass substrate, the assembled molecules nucleate and evolve to a liquid-liquid phase separation, or they will crystallize if the trapping laser is focused on the solution surface. Laser trapping can induce spatiotemporally the liquid and solid nucleation of glycine, and the dense liquid droplet or crystal formed can grow to a bulk scale. We can control the polymorph of the formed glycine crystal selectively by tuning trapping laser polarization and power. These results provide a new approach to elucidate dynamics and mechanism of crystallization and are the fundamental basis for studying not only enantioselective crystallization but also confined polymerization, trapping dynamics by ultrashort laser pulses, and resonance effect in laser trapping. © 2012 American Chemical Society. Source


Tsai C.-L.,Chang Jung Christian University | Chang H.-C.,Instrument Technology Research Center
Kybernetes | Year: 2016

Purpose – The purpose of this paper is to collate relevant literature on the theoretical background of regional innovation systems and factors that impact the operational effectiveness of regional innovation systems. Design/methodology/approach – The collated information is then used to determine the opinions of experts from industries within science-based parks, and the scholars on the researches of regional innovation systems in Taiwan. The analytic hierarchy process (AHP) is used to evaluate the critical factors of regional innovation systems. Findings – This study finds that industry cluster effects constitute the most significant operating factor for regional innovation systems within the Taiwanese science-based parks. In addition, this study not only confirms that partners or parent firm location which were advocated by Tödtling et al. are also critical to Taiwanese regional innovation systems, but also verifies how well the relationships to partners or parent firm are equally important for expansion the regional innovation systems. Research limitations/implications – The concepts of regional innovation system have been established since 1990, and related articles have been published from European and Asian scholars, however, seldom does literature offer questionnaires or research items to measure the operational effectiveness of a regional innovation system. Therefore this study has developed a questionnaire, by reviewing literature and verifying it by the AHP method, with Taiwan’s HsinChu Science Park as the subject case. For the contribution on theories, this study inducted the construction of new innovation environments, new interactional behavior in regional organization innovation, and injection of new resources into regional innovation as the three main constructs to influence the operational effectiveness of regional innovation systems. In addition, this study has used experts’ questionnaire answers and the AHP method to clarify the priority of factors to operate the regional innovation system. Practical implications – Industry cluster effect, construction of knowledge infrastructure and how close partners or parent firm are (distance and relationship) are the top three factors in HsinChu Science Park. The duties of the government are not merely picking good firms for the regional innovation system, but also making policies and defining regimes, providing a good business environment for campus firms, universities, and research institutions, as well as offering plenty of R&D funding to encourage industry-academia cooperation. Governments must invest in infrastructures, such as: establishing databases, libraries, information networks, the national technical standards for certification, and other public services, to facilitate industry-academia cooperation. Social implications – These research results indicate the operating essentials of regional innovation systems are not limited to interactions among regional organizations. This study suggests that the success or failure of a new regional innovation system would instead, be dependent on the regional environment, as in software planning and support, as well as the relationship of innovation with policy implementation and administration. Originality/value – Results showed that the top-five factors influencing the operational effectiveness of regional innovation systems are the industry cluster effect, the construction of knowledge infrastructure, how close to partner’s or parent’s firm (distance and relationship), import of foreign capital and technology, and the implementation of regional innovation policy. © 2016, © Emerald Group Publishing Limited. Source


Chang W.-T.,National Tsing Hua University | Hsueh Y.-C.,National Tsing Hua University | Huang S.-H.,National Tsing Hua University | Liu K.-I.,National Tsing Hua University | And 3 more authors.
Journal of Materials Chemistry A | Year: 2013

TiO2 multi-walled nanotube arrays (MWNTAs) were synthesized by atomic layer deposition (ALD) using anodic aluminum oxide (AAO) as the template. TiO2 and Al2O3 layers were alternately deposited into the AAO pores by ALD. The tube thickness and the gap span were controlled by the ALD cycle numbers of TiO2 and Al2O 3, respectively. A MWNT composed of two or three concentric tubes with different diameters was formed after removal of Al2O 3. Silver nanoparticles were then deposited on both inner and outer surfaces of the tubes by photochemical reduction. Degradation of methylene blue was carried out to evaluate the photocatalytic activity of bare and silver-loaded TiO2 MWNTAs. It was found that the amount of TiO 2, the reaction surface area, the crystalline phase, and silver modification were the factors to determine the photocatalytic activity. The triple-walled MWNTAs showed the best performance, and Ag loading further enhanced the activity. This journal is © The Royal Society of Chemistry 2013. Source


Yuyama K.-I.,National Chiao Tung University | Sugiyama T.,Instrument Technology Research Center | Masuhara H.,National Chiao Tung University
Journal of Physical Chemistry Letters | Year: 2013

We present laser trapping behavior of l-phenylalanine (l-Phe) at a surface of its unsaturated aqueous solution by a focused continuous-wave (CW) near-infrared (NIR) laser beam. Upon the irradiation into the solution surface, laser trapping of the liquid-like clusters is induced concurrently with local laser heating, forming an anhydrous plate-like crystal at the focal spot. The following laser irradiation into a central part of the plate-like crystal leads to laser trapping at the crystal surface not only for l-Phe molecules/clusters but also for polystyrene (PS) particles. The particles are closely packed at crystal edges despite that the crystal surface is not illuminated by the laser directly. The molecules/clusters are also gathered and adsorbed to the crystal surface, leading to crystal growth. The trapping dynamics and mechanism are discussed in view of optical potential formed at the crystal surface by light propagation inside the crystal. © 2013 American Chemical Society. Source


Huang K.-S.,I - Shou University | Lin Y.-S.,Hungkuang University | Yang C.-H.,I - Shou University | Tsai C.-W.,Ming Chuan University | Hsu M.-Y.,Instrument Technology Research Center
Soft Matter | Year: 2011

By applying the microfluidic emulsification and sorting processes, the formation of twin monodispersed droplets can be achieved in one step. The purpose of this study was to accurately separate the smaller of the twin droplets from the larger one to obtain two monodispersed microparticles. A bi-T-junction hybrid microchannel design was employed to control both emulsification and separation. The results show that the droplet sizes are comparable to the channel diameter and can be tuned by varying the shear rate of the oil phase relative to the aqueous phase. Due to the fact that the separation efficiency is close to 100% in this system, both of the collected larger and smaller droplets are highly monodispersed (RSD < 2% and 6%, respectively), and have high reproducibility. In addition, the proposed microfluidic device was employed to present a facile one-step synthetic approach for the preparation of twin monodispersed alginate microparticles entrapping quantum dots and Fe 3O 4 nanoparticles. The proposed microfluidic chip is capable of generating relatively uniform twin microparticles with sizes that can be well controlled. It is a simple, low cost, and high throughput process. In the future this apparatus could be applied to manufacture various twin monodispersed composite microvehicles to act as a smart drug delivery system. © 2011 The Royal Society of Chemistry. Source

Discover hidden collaborations