Continuous Flow Atmospheric Pressure Laser Desorption/Ionization Using a 6–7-μm-Band Mid-Infrared Tunable Laser for Biomolecular Mass Spectrometry

A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6–7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6–7-µm wavelength region corresponds to the characteristic absorption bands of various molecular vibration modes, including O–H, C=O, CH₃ and C–N bonds. Consequently, many organic compounds and solvents, including water, have characteristic absorption peaks in this region. This ion source requires no additional matrix, and utilizes water or acetonitrile as the solvent matrix at several absorption peak wavelengths (6.05 and 7.27 µm, respectively). The distribution of multiply-charged peptide ions is extremely sensitive to the temperature of the heated capillary, which is the inlet of the mass spectrometer. This ionization technique has potential for the interface of liquid chromatography/mass spectrometry (LC/MS).     

Angled long tip to tuning fork probes for atomic force microscopy in various environments

We expand the range of applications of a tuning fork probe (TFP) in frequency-modulation atomic force microscopy (FM-AFM) by attaching a long metal tip at a certain angle. By the combined flexure of the metal tip and the tuning fork prong, this TFP can change the direction of the detectable force by switching the resonance frequency, which has not been realized with conventional TFPs with short tips. The oscillatory behavior of the tip apex of the TFP is predicted by computer simulations and is experimentally confirmed with scanning electron microscope. FM-AFM operations using this TFP are performed in various environments, i.e., in ultrahigh vacuum, air, and water. FM-AFM images obtained at an atomic step of highly oriented pyrolytic graphite in air show a clear difference depending on the excitation frequency. It is also revealed that the higher order flexural modes of this TFP are advantageous for FM-AFM in water due to the reduction in the degree of hydrodynamic damping.     

Association of the Rho family small GTP-binding proteins with Rho GDP dissociation inhibitor (Rho GDI) in Saccharomyces cerevisiae

Previous attempts to use inverse dynamics solutions in direct dynamics simulations have failed to replicate the input data of the inverse dynamics problem. Measurement and derivative estimation error, different inverse dynamics and direct dynamics models, and numerical integration error have all been suggested as possible causes of inverse dynamics simulation failure. However, using a biomechanical model of the type typically used in gait analysis applications for inverse dynamics calculations of joint moments, we produce a direct dynamics simulation that exactly matches the measured movement pattern used as input to the inverse dynamic problem. This example of successful inverse dynamics simulation demonstrates that although different inverse dynamics and direct dynamics models may lead to inverse dynamics simulation failure, measurement and derivative estimation error do not. In addition, inverse dynamics simulation failure due to numerical integration errors can be avoided. Further, we demonstrate that insufficient control signal dimensionality (i.e., freedom of the control signals to take on different "shapes"), a previously unrecognized cause of inverse dynamics simulation failure, will cause inverse dynamics simulation failure even with a perfect model and perfect data, regardless of sampling frequency.     

正交异性板弯曲刚度系数的反分析方法

提出了通过测量位移来计算正交各向异性板弯曲刚度系数的迭代方法。此方法以有限元的反分析原理和系统辨识技术为基础，以正交各向异性板的弯曲刚度系数为位移的函数，当给出弯曲刚度系数的初值和位移测量值时，通过迭代计算可以得到弯曲刚度系数。给出了差分形式的迭代计算公式，讨论了位移测量模型、实验条件以及迭代计算中的收敛性等问题。实际算例表明，本文提出的方法对直接测试正交各向异性板的整体弯曲刚度系数是实用的。     

Decomposition of fluorocarbon gaseous contaminants by surfacedischarge-induced plasma chemical processing

The decomposition performance of surface discharge induced plasma chemical processing (SPCP) with a cylindrical ceramic-based reactor for chlorofluorocarbon gases was measured in atmospheric air, pure oxygen gas, or pure nitrogen gas. In the case of decomposition test for 1000 p.p.m. CFC-22 in air, a maximum decomposition rate of about 90% was recorded. In the case of the decomposition test for 100 p.p.m. CFC-113, more than 99% fluorocarbon could be removed. The decomposition mechanism of fluorocarbon is not yet known exactly but is assumed to be due to the effect of the surface discharge plasma near the discharge electrode. The decomposition rate for fluorocarbon in nitrogen gas was the largest among three gases (air, nitrogen, and oxygen), indicating the strong activity of the nitrogen radicals. A large ceramic reactor was also tested, and the decomposition performance was found to be proportional to the real electric power consumption under best conditions. The reaction products after the SPCP are not yet identified, but phosgene and its derivatives have not yet been found     

Room temperature scanning Hall probe microscopy using GaAs/AlGaAs and Bi micro-hall probes

A room temperature scanning Hall probe microscope system utilizing GaAs/AlGaAs and bismuth micro-Hall probes was used for magnetic imaging of ferromagnetic domain structures on the surfaces of crystalline thin film garnets and permanent magnets. The Bi micro-Hall probes had dimensions ranging between 0.25 and 2.8 microm2 and were fabricated using a combination of optical lithography and focused ion beam milling. The use of bismuth was found to overcome surface depletion effects associated with semiconducting micro-Hall probes. Our experiments demonstrated that Bi is a practical choice of material for fabricating sub-micron sized Hall sensors.     

Cyclic Peptides for Efficient Detection of Collagen

We report here a new class of collagen‐binding peptides, cyclic collagen‐mimetic peptides (cCMPs), that efficiently hybridize with the triple‐helix‐forming portions of collagen. cCMPs are composed of two parallel collagen‐like (Xaa‐Yaa‐Gly)_n strands with both termini tethered by covalent linkages. Enzyme‐linked immunosorbent assays and western blotting analysis showed that cCMPs exhibit more potent affinity toward collagen than reported collagen‐binding peptides and can specifically detect different collagen polypeptides in a mixture of proteins. Collagen secreted from cultured cells was detected by confocal microscopy with fluorescein‐labeled cCMP. The cCMP is also shown to detect sensitively folding intermediates in the endoplasmic reticulum, something that was difficult to visualize with conventional collagen detectors. Molecular‐dynamics simulations suggested that a cCMP forms a more stably hybridized product than its single‐chain counterpart; this could explain why cCMP has higher affinity toward denatured collagen. These results indicate the usefulness of cCMPs as tools for detecting denatured collagen.     

The tribological role of surface atoms: ultra-thin carbon and silver layers on the Si(111)

A few monolayers of a carbon film on an Si(111) substrate have been studied for tribological characteristics, focusing on the tribological role of the surface atoms.A monolayer of H and Ag on Si were also tested with a macroscopic diamond slider to examine the effect of the surface atoms on the friction, and it was observed that the sliding systems show an extraordinarily low friction in ultra-high vacuum. We could draw a conclusion: the chemical characteristics of the surface layer strongly affect the friction and nano-scale structures on the surface drastically change the macroscopic slider friction in these systems.     

Formation of Functionalized Nanowires by Control of Self‐Assembly Using Multiple Modified Amyloid Peptides

Amyloid peptides have great potential as building blocks in the creation of functional nanowires due to their natural ability to self‐assemble into nanofibrillar structures and because they can be easily modified with various functional groups. However, significant modifications of an amyloid peptide generally alter its self‐assembly property, making it difficult to construct functionalized fibrils with a desired structure and function. In this study, a very effective method to overcome this problem is demonstrated by using our structure‐controllable amyloid peptides (SCAPs) terminated with a three‐amino‐acid‐residue cap. The method consists on mixing two or more structurally related amyloid peptides with a fraction of modified SCAPs which co‐assemble into a fibril. This SCAP‐mixing method provides remarkable control over the self‐assembly process both on the small oligomers level and the macroscopic fibrils level. Furthermore, it is shown that the modified peptides imbedded in the resulting fibril can subsequently be functionalized to generate nanowires with the desired properties, highlighting the importance of this SCAP method for nanotechnology applications.     

Crosstalk delay analysis of a 0.13-/spl mu/m node test chip and precise gate-level simulation technology

The impact of crosstalk on delay was examined by measuring a test chip manufactured with a 0.13-/spl mu/m node technology. This examination revealed three requirements for precise and fast gate-level simulation technology: 1) consideration of degradation change dependent on relative signal arrival time over a wide range; 2) static timing analysis-based operation; and 3) quantitative estimation of the degradation accumulation caused by multiple aggressors. A candidate for such simulation technology is provided, and its highly precise characteristics are demonstrated through comparisons between measurement and simulation. In a test structure with two aggressors, the maximum error between the measured and simulated degradation was reduced to less than one-sixth of that with a conventional method.