A novel potassium sensing oligonucleotide (PSO) was constructed by attaching fluorophores 6-FAM and 6-TAMRA to the 5'- and 3'-termini of d(GGG TTA GGG TTA GGG TTA GGG), respectively. The affinity of PSO for K+ was 43 000 times greater than that for Na+, high enough selectivity enabling quantitation of K+ specifically in the presence of excess Na+. Fluorescence resonance energy transfer (FRET) to 6-TAMRA from 6-FAM of PSO was observed only in the presence of K+. This phenomenon is based on the approximation of the two fluorophores upon formation of a guanine quartet mediated by K+. Furthermore, the fluorescent color of PSO changes from yellow to red upon formation of the complex, thereby enabling visualization of K+ in aqueous media.
A novel microwave discharge utilizing a spokewise antenna was
applied for the fast deposition of hydrogenated microcrystalline
silicon (µc-Si:H) film from SiH4 and Ar without the
H2 dilution method. Systematic deposition studies were employed
with total pressure, H2 dilution ratio and flow rate of
SiH4, Fr[SiH4], as variables, combined with optical
emission spectroscopy (OES) and Langmuir probe characterizations. It
was found that the deposition rate exhibits a maximum at 40–50 mTorr
at the axial distance of 10 cm from the quartz glass plate and the
film crystallinity strongly depend on the total pressure. Correlation
among OES signal intensity, SiH, the intensity ratio,
I
Hα
/I
Si*
, deposition rate and film
crystallinity were demonstrated. By combining the SiH4 depletion
and lower pressure conditions, a high deposition rate of 40 Å/s
was achieved in µc-Si:H growth with high crystallinity and
photosensitivity from SiH4 and Ar plasma.
Human [G(3)(TTAG(3))(3)] and Oxytricha [G(4)(T(4)G(4))(3)] telomere model oligonucleotides, PSO-1 and PSO-2, bearing two fluorophores, 6-carboxyfluorescein (6-FAM) and 6-carboxytetramethylrhodamine (6-TAMRA) at their 5'- and 3'-termini, respectively, were synthesized. Both of them can form an intramolecular antiparallel tetraplex upon addition of K(+), and an enhanced fluorescence resonance energy transfer (FRET) was observed. PSO-1 showed a 43,000 times higher selectivity for K(+) against Na(+). Fluorometric and circular dichroism spectrophotometric studies revealed that this system is useful for the evaluation of the interaction of different telomeric repeat oligonucleotide sequences with metal ions.
A low temperature, uniform, high-density plasma is produced by an ultra-high-frequency (UHF) discharge using a new spokewise antenna. The plasma is uniform within ±5% over a diameter of 30 cm. The plasma density, 1×1011 cm-3, for low electron temperatures of 1.5-2.0 eV, is almost proportional to the UHF power even at a low UHF power. No magnetic field is needed to maintain a high-density plasma. Consequently, the plasma source is fairly simple and lightweight. The plasma source can accomplish a notch-free poly-Si etching profile with a high etching rate at a narrow space pattern of less than 0.3 µ m.
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