Femtosecond laser-induced stimulation of a single neuron in a neuronal network

We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca²⁺ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca²⁺ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution.     

Synthesis of poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate) with 5,10,15,20‐tetraphenylporphinato platinum(II) moiety as an oxygen‐sensing dye for pressure‐sensitive paint

Pressure‐sensitive paint (PSP), which consists of luminescent molecules embedded in an oxygen‐permeable polymer, has been developed for use in wind‐tunnel experiments. To improve the PSP technique, a novel luminescent methacrylate monomer, 5‐[4‐(2‐methacryloyloxyethoxycarbonyl)phenyl]‐10,15,20‐triphenylporphinato platinum(II), was synthesized and copolymerized with isobutyl methacrylate and 2,2,2‐trifluoroethyl methacrylate to produce a dye‐pendant copolymer ( 2 ). The introduction of 5,10,15,20‐tetraphenylporphinato platinum(II) (PtTPP) dye into 2 was confirmed by ultraviolet–visible spectroscopy and extended X‐ray absorption fine structure measurements. The extent of PtTPP dye incorporation in 2 was proportional to the molar fraction of the PtTPP‐pendant methacrylate monomer in the feed. The oxygen‐sensing property of 2 was compared with that of a PSP consisting of PtTPP dye embedded in poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate). Although the simple mixture of PtTPP and poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate) showed a marked deviation from a single Stern–Volmer relation, novel copolymer 2 gave a highly linear Stern–Volmer plot. This was unequivocal evidence of dye conjugation on the oxygen‐sensing polymer film. © 2005Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2997–3006, 2005     

Crystal structure of 7,8-dihydroxy-4-methylcoumarin.

The structure of 7,8-dihydroxy-4-methylcoumarin was determined by an X-ray diffraction method. The compound crystallized in the triclinic space group P1, Z = 2, with a = 7.631(2), b = 9.456(5), c = 7.075(3)A, alpha = 103.13(3), beta = 91.84(3), gamma= 68.21(3) degrees, and V= 460.9(3)A3. The X-ray crystal structure was also compared with those of 5,7-dihydroxy-4-methylcoumarin and 7-hydroxy-4-methylcoumarin.     

Depth profiling of ultra trace metal impurities in polytetrafluoroethylene wares by surface scraping and acid-vapor extraction followed by ICP-MS analysis.

This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities.     

Synthesis of macrocycles having tröger base skeletons “[2.2]cyclic tröger base”

[2.2]Cyclic Tröger base2 was synthesized by the condensation of 1,2-bis (4-aminopheyl) ethane with paraformaldehyde under acidic condition in 43.8% yield. [2.2]Cyclic Tröger base2 was separated into meso form and racemate by fractional crystallization or using HPLC. Resolution of the racemate into its optical antipodes by passing the racemate through an activated D-(+)-lactose column was partially succeeded.Presented at the 15th Symposium on Structural Organic Chemistry, Kyoto, October, 1982.The trivial name [2.2]cyclic Tröger base is used because of the cumbersome nomenclature.10,12,25,32-Tetraazanonacyclo[19.7.7.1^4,8.1^14,18.1^25,32.0^7,12.0^7,12.0^10,15.-0^24,34.0^27,31] octatriaconta-1(29),4,6,8(36),14,16,18(37),21,23,27,-30,34-dodecaene.     

Third order efficiency implies fourth order efficiency: A resolution of the conjecture of J. K. Ghosh

Under suitable regularity conditions, it is shown that a third order asymptotically efficient estimator is fourth order asymptotically efficient in some class of estimators in the sense that the estimator has the most concentration probability in any symmetric interval around the true parameter up to the fourth order in the class. This is a resolution of the conjecture by Ghosh (1994, Higher Order Asymptotics, Institute of Mathematical Statistics, Hayward, California). It is also shown that the bias-adjusted maximum likelihood estimator is fourth order asymptotically efficient in the class.     

Broadly tunable UV-blue picosecond pulsed laser and its application for biological imaging

We have achieved a rapid and random wavelength tuned picosecond pulsed laser and a widely tunable UV-blue picosecond pulsed laser by using the intracavity second harmonic generation of the laser. The tuning range was from 384 to 434 nm with picosecond pulse oscillation. In addition, we demonstrated biological imaging using a fluorescent protein excited by the widely tunable UV-blue picosecond pulsed laser. We found that the laser is suitable for biological imaging using the fluorescent protein as an excitation light source without damages.