Single-cell Trapping Using Microwell Arrays Fabricated from Self-assembled Particle Monolayers

This paper proposes a self-assembly fabrication method of microwells and investigates the effect of surface treatment for the cell trapping. The target cell is unicellular cyanobacterium Synechocystis sp. strain PCC 6803, which has been widely investigated as a model organism for photosynthesis. The self-assembly monolayer of polystyrene particles (3.0 μm diameter) etched by reactive-ion etching was used as a template of polydimethylsiloxane molds. The well diameter in the mold could be controlled by the etching time. The cell-trapping efficiency was discussed with the viewpoint of hydrophilically treatment and poly-L-lysine treatment on the well arrays.     

Explanation of Human Skin Color by Multiple Linear Regression Analysis Based on the Modified Lambert-Beer Law

Quantitative analysis of human skin color is needed in the medical and cosmetic fields. Because of the strong light scattering by biological tissues, however, analysis of skin color has not yet been fully successful. Human skin color is dominated by the colors of blood and melanin which are modified by scattering. Exposure of human skin to hot water or UV-ray changes its color because the absorbance spectrum of reflection from the human skin, and the changes in the absorbance spectra of reflection reflect the absorbance spectra of blood and melanin which are the absorption spectrum distorted by scattering. By applying the modified Lambert-Beer law, the absorbance spectrum of reflection from human skin can be expressed proportional to those distorted absorbance spectra of blood and melanin. Multiple linear regression analysis is successfully used to reproduce the absorbance spectrum of reflection from human skin from the distorted absorbance spectra of blood and melanin.     

Quantitative analysis of near surfaces three‐dimensional orientation of polymer chains in PET and PEN films using polarized ATR FTIR spectroscopy

Polarized attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy was utilized to characterize the three‐dimensional orientation of polymer chains near highly anisotropic surfaces generated by uniaxial drawing. A versatile method was proposed to analyze the molecular orientation of the polymers by combining the experimental refractive indices and optimized contact pressure by an anvil for solving the optical contact problem. This method is effective even when changes in the molecular orientation along the thickness direction caused by drawing are remarkable. In addition, this method enables quantitative comparison of the molecular orientation among different polymers in the same coordinate system. From the molecular orientation analysis of poly (ethylene terephthalate) (PET) and poly (ethylene naphthalate) (PEN), it was revealed that this method has a broader range of applications with high accuracy in estimating the molecular orientation of polymers compared with the conventional methods. The significant changes in the molecular orientation caused by uniaxial and biaxial drawing of PET and PEN films were quantitatively analyzed, and the reasons for the significant in‐plane orientation of PEN chains on the film plane are discussed. In addition, the difference in the molecular orientation between both sides of the films was also demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 870–879, 2010     

Cleavage of a P=P Double Bond Mediated by N-Heterocyclic Carbenes

The reaction of the bulky diphosphenes (Rind)P=P(Rind) ( 1 ; Rind=1,1,3,3,5,5,7,7-octa-R-substituted s-hydrindacen-4-yl) with two molecules of N-heterocyclic carbene (NHC; 1,3,4,5-tetramethylimidazol-2-ylidene) resulted in the quantitative formation of the NHC-bound phosphinidenes NHC→P(Rind) ( 2 ), along with the cleavage of the P=P double bond. The reaction times are dependent on the steric size of the Rind groups (11 days for 2 a (R=Et) and 2 h for 2 b (R=Et, Me) at room temperature). The mechanism for the double bond-breaking is proposed to proceed via the formation of the NHC-coordinated, highly polarized diphospehenes 3 as an intermediate. Approach of a second NHC to 3 induces P−P bond cleavage and P−C bond formation, which proceeds through a transition state with a large negative Gibbs energy change to afford the two molecules of 2 , thus being the rate-determining step of the overall reaction with the activation barriers of 80.4 for 2 a and 29.1 kJ mol⁻¹ for 2 b .     

Mutual conversion between stretched and contracted helices accompanied by a drastic change in color and spatial structure of poly(phenylacetylene) prepared with a [Rh(nbd)Cl]2‐amine catalyst

The yellow‐colored poly(phenylacetylene), Poly( Y ), is obtained from phenylacetylene using a [Rh(nbd)Cl]₂‐NEt₃ catalyst in ethanol at 25 °C. The color of Poly( Y ) drastically changes into red Poly( R ) or reddish‐black Poly( B ) by immersion in acetylacetone or exposure to chloroform vapor, respectively. Poly( R ) is also created from Poly( B ) by contact with acetylacetone. Poly( Y ) is regenerated from both Poly( R ) and Poly( B ) by reprecipitation from their chloroform solution into methanol. Wide‐angle X‐ray scattering (WAXS) patterns of Poly( Y ) and Poly( R ) correspond to a pseudohexagonal crystal called a columnar as stretched cis‐transoid and contracted cis‐cisoid helices, respectively. These helical diameters and pitch widths obtained from the WAXS measurements are agreed with those of MMFF94 calculation models. The smallest helical pitch width is 3.3 Å for Poly( R ) and Poly( B ). Moreover, information regarding the size and ordering of the vacant space within each polymer is estimated by using ¹²⁹Xe NMR technique. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 752–759     

Performance assessment of a new laser system for efficient spin exchange optical pumping in a spin maser measurement of <Superscript>129</Superscript>Xe EDM

We demonstrate spin-exchange optical pumping of ¹²⁹Xe atoms with our newly made laser system. The new laser system was prepared to provide higher laser power required for the stable operation of spin maser oscillations in the ¹²⁹Xe EDM experiment. We studied the optimum cell temperature and pumping laser power to improve the degree of ¹²⁹Xe spin polarization. The best performance was achieved at the cell temperature of 100 ^°C with the presently available laser power of 1 W. The results show that a more intense laser is required for further improvement of the spin polarization at higher cell temperatures in our experiment.     

Flow Synthesis of Plasmonic Gold Nanoshells via a Microreactor

Gold nanoshells with tunable surface plasmon resonances are a promising material for optical and biomedical applications. They are produced through seed‐mediated growth, in which gold nanoparticles (AuNPs) are seeded on the core particle surface followed by growth of the gold seeds into a shell. However, synthetic gold nanoshell production is typically a multistep, time‐consuming batch‐type process, and a simple and scalable process remains a challenge. In the present study, a continuous flow process for the seed‐mediated growth of silica–gold nanoshells is established by exploiting the excellent mixing performance of a microreactor. In the AuNP‐seeding step, the reduction of gold ions in the presence of core particles in the microreactor enables the one‐step flow synthesis of gold‐decorated silica particles through heterogeneous nucleation. Flow shell growth is also realized using the microreactor by selecting an appropriate reducing agent. Because self‐nucleation in the bulk solution phase is suppressed in the microreactor system, no washing is needed after each step, thus enabling the connection of the microreactors for the seeding and shell growth steps into a sequential flow process to synthesize gold nanoshells. The established system is simple and robust, thus making it a promising technology for producing gold nanoshells in an industrial setting.     

Transition-metal-free controlled polymerization for poly(p-aryleneethynylene)s

A transition-metal-free controlled polymerization for the attainment of poly(p-aryleneethynylene)s is developed. The polymerization of 1-pentafluorophenyl-4-[(trimethylsilyl)ethynyl]benzene with a catalytic amount of fluoride anions proceeds in a chain-growth-like manner to afford polymers with controlled molecular weights and low polydispersity indexes. The mechanism involves a pentacoordinated fluorosilicate as a key intermediate. The anionic “living” nature of this process is applied to block copolymerization and also surface-terminated polymerization.     

Improvement of magnetic intergranular isolation and evaluation of read/write characteristics on SmCo5 perpendicular magnetic thin films

SmCo₅ alloy is a promising candidate for ultra-high-density perpendicular magnetic recording (PMR) media because of its high uniaxial magnetocrystalline anisotropy K_u of more than 1.1×10⁸ erg/cm³. Previously, we successfully achieved high K_u in a sputter-deposited SmCo₅ thin film by introducing a Cu/Ti dual underlayer. However, in order to apply the SmCo₅ films to practical PMR media, it is necessary to decrease medium noise. A granulated magnetic film comprising of small and magnetically decoupled grains is effective in reducing the medium noise. In this paper, we have proposed a new granular film that is fabricated by partial thermodiffusion of Cu between the Sm-Co continuous layer and the Cu underlayer, which is granulated using compositional segregation caused by the addition of Ta₂O₅. We have analyzed the magnetic properties, magnetic domain size, and magnetization reversal process of the proposed SmCo₅ film. The magnetic domain size decreased and the magnetization reversal process changed from the magnetic-wall-motion mode to a coherent rotation mode to some extent on isolation of magnetic grains. The read/write characteristics of granulated SmCo₅ double-layered media were also evaluated. The medium noise decreased and the signal-to-noise ratio increased for the granulated double-layered (PMR) medium.     

Characterization of aluminum species with nitrate, perchlorate and sulfate ions in the positive and negative ion mode by electrospray ionization mass spectrometry

The application of electrospray ionization mass spectrometry (ESI-MS) for aluminum speciation in the positive and negative ion modes was discussed. Aluminum nitrate, perchlorate and sulfate solutions were measured by ESI-MS. In the positive ion mode, aluminum species containing anions (Al-L; L=NO3, ClO4 and SO4) were identified, while [Al(OH)2(H2O)n]+ (n=2-4) were the main species. The affinity of the anions with Al3+ estimated by ESI-MS was consistent with the hardness of the anions (hard and soft acids and bases principle) and the results from 27Al nuclear magnetic resonance studies. This indicates that the results observed from the positive ion mode preserved the chemical state of aluminum in the solution. In the negative ion mode, [Al(OH)4-nLn]- (n=0-2, L=NO3, ClO4) were the main species, which were considered to be converted from positive aluminum species, [Al(OH)(H2O)n]+ (n=2-4), by the successive addition of anions. Anions did not only attach to one aluminum ion but also bridged two aluminum ions. In Al2(SO4)3 solution, the behavior of SO4(2-) in the negative ion mode differed from that of NO3- and ClO4-. This may reflect the affinity of SO4(2-) with Al3+ in the solution or in the mass spectrometer or in both. Finally, detection mechanisms for the aluminum species in the solution are proposed for both the positive and negative ion modes. It is shown that ESI-MS can be used to observe the interaction between Al3+ and anions. We show the importance of the interpretation of the results by ESI-MS for obtaining new information of the metal species in the solution.