Nanomaterial-based surface-assisted laser desorption/ionization mass spectrometry of peptides and proteins

We have investigated six nanomaterials for their applicability as surfaces for the analyses of peptides and proteins using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Gold nanoparticles (NPs) were useful nanomateriais for small analytes (e.g., glutathione); Pt nanosponges and Fe₃O₄ NPs were efficient nanomaterials for proteins, with an upper detectable mass limit of ca. 25 kDa. Nanomateriais have several advantages over organic matrices, including lower limits of detection for small analytes and lower batch-to-batch variations (fewer problems associated with “sweet spois”), when used in laser desorption/ionization mass spectrometry.     

Synthesis,Antiproliferative, and Antiplatelet Activities of Oxime‐Containing 3,4‐Dihydroquinolin‐2(1H)‐One Derivatives

Some oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were synthesized and evaluated for their antiplatelet and antiproliferative activities. These compounds were synthesized via alkylation of hydroxyl precursors followed by the reaction with NH₂OH. The preliminary assays indicated that (Z)‐7‐[2‐(4‐fluorophenyl)‐2‐(hydroxyimino)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13c) is the most active against U46619 induced platelet aggregation with an IC₅₀ value of 3.51 μM. For the inhibition of AA‐induced aggregation, (E)‐6‐[2‐(hydroxyimino)propoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (15 ) is the most potent with an IC₅₀ value of 1.85 μM. These oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive against thrombin induced platelet aggregation with an IC₅₀ value of greater than 26.78 μM. For the antiproliferative activity, most of these oxime‐containing 3,4‐dihydroquinolin‐2(1H)‐one derivatives were inactive while (Z)‐7‐[2‐(hydroxyimino)‐2‐(naphthalen‐2‐yl)ethoxy]‐3,4‐dihydroquinolin‐2(1H)‐one (13a) exhibited only marginal activities with GI₅₀ value of 7.63, 7.34 and 6.36 μM against the growth of NPC‐TW01, NCI‐H661, and Jurkat respectively.     

Simultaneous self-mode-locking of TEM<Subscript>0,0</Subscript> and TEM<Subscript>1,0</Subscript> modes in a Nd:YVO<Subscript>4</Subscript> laser: Application for measuring the thermal focal length

We demonstrate that the simultaneous self-mode-locking of TEM_0,0 and TEM_1,0 modes can be achieved in a standard end-pumped Nd:YVO₄ laser. With this simultaneous self-mode-locking, the transverse beat frequency can be accurately measured as a function of the absorbed power. We employ the measured beat frequency and the cavity theory to precisely determine the effective focal length of the thermal lens in the gain medium.     

Comparison of CALIPSO and ground-based lidar profiles over Chung-Li, Taiwan

We report the first inter-comparison of vertical profiles of aerosols and clouds derived from space (CALIPSO) and ground based lidar over Chung-Li, Taiwan. Results show that inter-comparison is closer in case of aerosols than clouds. The strength/shortcoming of the comparison has been also discussed. An iterative calculation to retrieve extinction-to-backscatter ratio (lidar ratio) by using sun-photometer and CALIPSO data is also documented. By using the mentioned method, a mean lidar ratio of 23.5±8.2 sr was found. The derived lidar ratios are lower than former studies. The possible reasons for the difference have been discussed in this paper. The discussed methodology will be helpful to reduce the uncertainty of optical parameters derived from lidar data especially near the surface where the atmosphere is inhomogeneous.     

Visualizing electronic chirality and Berry phases in graphene systems using photoemission with circularly polarized light

Electronic chirality near the Dirac point is a key property of graphene systems, which is revealed by the spectral intensity patterns as measured by angle-resolved photoemission spectroscopy under various polarization conditions. Specifically, the strongly modulated circular patterns for monolayer (bilayer) graphene rotate by ±90° (±45°) in changing from linearly to circularly polarized light; these angles are directly related to the phases of the wave functions and thus visually confirm the Berry's phase of π (2π) around the Dirac point. The details are verified by calculations.     

无氧铜环颈缩区孔洞长大与局域化温升效应研究

 利用金相显微镜,对电磁加载下无氧铜（M态TU1）环碎片的颈缩部位进行了金相分析,观察到了颈缩区孔洞长大、汇通及孔洞壁熔化现象。利用球形孔洞模型,分析了颈缩区孔洞长大条件,发现周向偏应力更适合于描述膨胀环颈缩区的孔洞长大。据此,讨论了颈缩区的局域化温升效应。研究结果为延性金属环膨胀颈缩失稳的细观机理研究提供参考。     

Controlling number of lasing modes for designing short-cavity self-mode-locked Nd-doped vanadate lasers

A short-cavity Nd:YVO₄ laser is employed to confirm that a spontaneous mode locking (SML) typically occurs without employing an extra nonlinearity. We further experimentally demonstrate that reducing the number of longitudinal lasing modes can diminish the phase fluctuation and effectively improve the SML pulse stability. Considering the spatial hole-burning (SHB) effect, an analytical expression is derived to accurately estimate the number of longitudinal lasing modes for a practical design guideline.     

Method for suppressing the mirror image in Fourier-domain optical coherence tomography

A method, novel to our knowledge, for effective mirror image suppression in Fourier-domain optical coherence tomography based on a phase shift between neighboring A-mode scans is demonstrated. By realizing that the phase shifts of the real and mirror images are mutually reversed and assuming that the real image intensities of the two successive A-mode scans are the same, we can solve a set of two coupled equations to obtain the real image signals. The images based on the scanning of a high-resolution spectral-domain optical coherence tomography system are processed to show effective mirror image suppression results. Compared with a similar method of broad application, our approach has the advantages of shorter process time and higher flexibility in selecting the concerned image portions for processing.     

Linear maps leaving the alternating group invariant

Let A_n be the group of n×n even permutation matrices, and let V_n be the real linear space spanned by A_n. The purpose of this note is to characterize those linear operators φ on V_n satisfying φ(A_n)=A_n. This answers a question raised by C.K. Li, B.S. Tam, N.K. Tsing [Linear Algebra Appl., to appear].     

Method for modulating the wafer bow of free-standing GaN substrates via inductively coupled plasma etching

The bowing curvature of the free-standing GaN substrate significantly decreased almost linearly from 0.67 to 0.056 m⁻¹ (i.e. the bowing radius increased from 1.5 to 17.8 m) with increase in inductively coupled plasma (ICP) etching time at the N-polar face, and eventually changed the bowing direction from convex to concave. Furthermore, the influences of the bowing curvature on the measured full width at half maximum (FWHM) of high-resolution X-ray diffraction (HRXRD) in (0 0 2) reflection were also deduced, which reduced from 176.8 to 88.8 arcsec with increase in ICP etching time. Decrease in the nonhomogeneous distribution of threading dislocations and point defects as well as V_Ga–O_N complex defects on removing the GaN layer from N-polar face, which removed large amount of defects, was one of the reasons that improved the bowing of the free-standing GaN substrate. Another reason was the high aspect ratio of needle-like GaN that appeared at the N-polar face after ICP etching, which released the compressive strain of the free-standing GaN substrate. By doing so, crack-free and extremely flat free-standing GaN substrates with a bowing radius of 17.8 m could be obtained.