Fluorescent modification for peptide sequencing by postsource decay-matrix assisted laser desorption/ionization-mass spectrometry

The sequential analysis of a peptide of CDYEGRLI, relating to the nucleic proteins in influenza virus, was performed by the postsource decay (PSD) fragmentation method using matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). The sequence of the peptide was difficult to analyze by MALDI-MS since the PSD fragment ions of the peptide were almost never observed and were not amenable to complete sequence interpretation. The peptide was modified by 4(5)-(iodoacetamide) fluorescent reagent to improve the sensitivity of the MALDI-PSD fragment spectrum. In the spectrum of the fluorescent modified peptide, almost all sequential b-series fragment ions were observed clearly, which was sufficient for complete sequence interpretation. The results indicate the advantage of fluorescent modification for the total sequencing of the peptides by MALDI-MS.     

Pseudogap formation in the intermetallic compounds (Fe1-xVx)3Al

Optical conductivity data of the intermetallic compounds (Fe1-xVx)3Al ( 0相似文献   

Measurement of D(d,p) T Reaction Cross Sections in Sm Metal in Low Energy Region (10≤Ed≤20keV)

To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D(d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2K for beam energies ranging from 10 to 20keV. The thick target yields of protons emitted in the D(d,p) T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2K is deduced tobe 520±56eV. As compared with the value achieved in the gas target, thecalculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section σ(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2K are obtained, respectively.     

磁场构型的影响及用于RIKEN的RIBF项目的新型ECR离子源

We measured the main plasma parameters(density of electron,temperature of electron and ion confinement time)and beam intensity of various heavy ions as a function of B_(min).The B_(min) strongly affects the field gradient at the resonance zone,consequently the plasma parameters and beam intensity are changed. Based on these experimental results,we started to construct new 18GHz ECRIS and make a detailed design of the 28GHz SC-ECRIS for RIKEN RI beam factory project.     

ECR离子源引出束流周期性波动研究

Earlier we reported an ion current jump which was observed at a fixed negative biased disc potential in the 6.4GHz ECR ion source at VECC,Kolkata.In a recent experiment with neon ions,we measured the time spectra of the ion current and observed the presence of a burst frequency in the kilohertz range.This frequency shows a correlated jump with the ion current jump described above.Another interesting feature is that the observed burst frequency shows a good linear correlation with the extracted ion current.The higher the ion current,the higher is the burst frequency.This means that current per burst is a constant factor;when there are more number of bursts,the current also increases.     

Practical optical frequency measurement system around 1.5 μm based on an acetylene-stabilized laser-locked optical frequency comb

We have developed a practical and precise frequency measurement system at 1.5 μm telecommunication band. An electro-optic-modulator based optical frequency comb is phase-locked to a dither-free acetylene-stabilized laser to realize an optical frequency comb with frequency uncertainty of 10 kHz (5 × 10⁻¹¹) and the linewidth of 15 kHz. The present frequency comb can be also used as an optical frequency reference grid defined by ITU-T (International Telecommunication Union, Telecommunication Standardization Sector). Using the present frequency measurement system, we have demonstrated the first optical frequency measurement of ¹²C¹⁶O overtone absorption lines around 1.56 μm with the uncertainty of lower than 900 kHz.     

Synthesis of diblock methylcellulose derivatives with regioselective functionalization patterns

This article describes a new synthesis strategy to prepare diblock copolymers as model compounds for industrially produced cellulose ethers exemplified with methylcellulose (MC). To elucidate a key structure for thermoreversible gelation of MC, five regioselectively methylated celluloses 1 – 5 (236, 23, 26, 3, and 6 MC), five corresponding methyl‐β‐D‐glucopyranosyl‐(1→4)‐cellulosides 6 – 10 , and five equiv methyl‐β‐D‐glucopyranosyl‐(1→4)‐β‐D‐glucopyranosyl‐(1→4)‐cellulosides 11 – 15 were synthesized for the first time via combination of the glycosyl trichloroacetimidate method and the acid‐catalyzed methanolysis method. The structure of compounds 1 – 15 was confirmed by means of NMR spectroscopy and MALDI‐TOF MS. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Heavy-Ion-Induced Sucrose and L-α-Alanine Radicals Investigated by EPR

We investigated the details of sucrose and L-α-alanine radicals produced by heavy-ion irradiation with various linear energy transfer (LET) values. The impact of the heavy ions on samples produced stable free radicals, which were analyzed by electron paramagnetic resonance (EPR). The spectral patterns obtained were similar among those for the irradiation of carbon (C), neon (Ne), silicon (Si), and argon (Ar) ions. The radical production of irradiated sucrose and alanine samples showed a linear relation with the absorbed dose. The total spin concentration obtained by heavy-ion irradiation decreases as logarithmic function of the LET. Quantitative EPR analysis showed that the production of sucrose and alanine radicals depended on both the ion species and the LET values under the same dose. Moreover, the radical-production cross sections for sucrose and alanine irradiated with C ions (290 MeV/u) were about 1.3 · 10⁻⁸ and about 3.0 · 10⁻⁹ μm², respectively. The results of the cross section suggest that each molecule becomes a stable radical with the interaction of several particles. Authors' address: Kouichi Nakagawa, Radioisotope Research Center, Fukushima Medical University, 1 Hikari-gaoka, Fukushima 960-1295, Japan