The Effect of γ Phosphate Modified Deoxynucleotide Substrates on PCR Activity and Fidelity

Controlling PCR fidelity is an important issue for molecular biology and high-fidelity PCR is essential for gene cloning. In general, fidelity control is achieved by protein engineering of polymerases. In contrast, only a few studies have reported controlling fidelity using chemically modified nucleotide substrates. In this report, we synthesized nucleotide substrates possessing a modification on P_γ and evaluated the effect of this modification on PCR fidelity. One of the substrates, nucleotide tetraphosphate, caused a modest decrease in Taq DNA polymerase activity and the effect on PCR fidelity was dependent on the type of mutation. The use of deoxyadenosine tetraphosphate enhanced the A : T→G : C mutation dramatically, which is common when using Taq polymerase. Conversely, deoxyguanosine tetraphosphate (dG4P) suppressed this mutation but increased the G : C→A : T mutation during PCR. Using an excess amount of dG4P suppressed both mutations successfully and total fidelity was improved.     

An improved control strategy for hybrid series active filter dealing with unbalanced load

This article presents an improved control strategy for hybrid series active power filters (HSAFs) working with nonlinear and unbalanced three‐phase three‐wire loads. An algorithm based on the instantaneous power theory is introduced to precisely extract only harmonic components from supply current, even this current is contaminated with negative sequence components due to the imbalance of the load. An improved control strategy based on that sequence extraction algorithm is proposed and investigated in detail by numerical simulations. The proposed control method has shown a better performance in mitigating harmonics, especially for the nonlinear and unbalanced loads. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Selective observation of starch in a water plant using optical sum-frequency microscopy

The photosynthesis, transfer, and storage of starch are the most important biogenic processes occurring in plants. In order to observe the colorless and transparent starch granules in a plant, a chemical pretreatment such as staining of the starch is currently required, which seriously damages the tissue cells in the plant. We demonstrate that nondestructive chemical analysis of starch granules in a plant can be performed by using optical second-harmonic and sum-frequency microscopy. These techniques for in vivo analysis will provide extremely useful information about saccharides in a plant and can be extended to the analysis of many other materials, from living tissue to semiconductors.     

Hollow fibers for delivery of harmonic pulses of Q-switched Nd:YAG lasers

Flexible hollow fibers for delivery of the second, third, and fourth harmonic pulses of Q-switched Nd:YAG lasers are introduced. For the doubled (532-nm) wavelength, we fabricated a hollow fiber with an internal metal and polymer film by using a silver-mirror plating and a liquid-phase-coating method. For tripled (355-nm) and quadrupled (266-nm) Nd:YAG in the ultraviolet region, we fabricated aluminum hollow fibers with or without an internal polymer layer by using the metal-organic chemical-vapor deposition method. Both types of fiber show high stability for the transmission of high-peak power laser pulses with low transmission losses.     

A method of direct particle deposition on a carbon planchet to study mineral dust in human lung by scanning electron microscopy

Following Na-hypochlorite digestion of lung tissue, mineral particles extracted in the chloroform layer were deposited directly on a pre-smoothed carbon planchet for combined scanning electron microscopy and X-ray energy dispersive spectrometry (SEM and XEDS). Total mineral particle counts were obtained, and detailed physical characteristics of the fibrous particles were documented at 600, 1,500, 4,500 and 9,000 x in three lungs without, and one lung with, histories of occupational exposure. This preparation method was simple, collected more than 99% of identifiable mineral particles in the chloroform layer, gave excellent object to background contrast without heavy metal coatings, and was suitable for XEDS. Comparable fibrous particles from the chloroform layer could also be studied by selected-area electron diffraction to complement the results of XEDS. By this method, we found particles or fibers larger than 0.1 μm were readily counted and measured at 4,500 x. At 600 x, ferruginous bodies were found to be more than twice in number than when sought for by light microscopy. It was determined that 4,500 x is the most efficient magnification to examine and diagnose this type of specimen. The present study illustrates the importance of determining the most efficient magnification to be utilized in particle counts.