Orientation of nanowires consisting of poly(3-hexylthiophene) using strong magnetic field

Nanowires consisting of regioregular poly(3-hexylthiophene) (P3HT) as a conducting polymer were prepared using p-xylene. Magnetic processing of the nanowires was carried out using two superconducting magnets with horizontal (B_max = 8 T) and vertical (B_max = 10 T) directions. The formation of the nanowires was confirmed by atomic force microscopy (AFM) measurement. The results from the AFM images and the polarized absorption spectra on glass plates indicated that the nanowires partly oriented themselves with their long axes, which are parallel to the π–π stacking direction, being perpendicular to the magnetic field. The magnetic orientation is most likely ascribed to anisotropy in the magnetic susceptibilities of the ordered P3HT in the nanowires.     

Preparation of an activated carbon artifact: oxidative modification of coconut shell-based carbon to improve the strength

Coconut shell-based activated carbon was oxidized in aq. H₂SO₄, HNO₃ and H₂O₂ to induce surface oxygen functional groups on its surface and to increase the mechanical strength of the resultant activated carbon artifact with PVB as a binder. Although all oxidation was confirmed to significantly increase the strength, aq. H₂O₂ was found to be most effective, giving strength as high as 6000 kPa, which is believed to be sufficient for the electrode of an electric double layer capacitor (EDLC). The increase of CO₂ evolving groups induced on the surface of activated carbon appears to be responsible for the strength increase. There was an optimum extent of oxidation for the strength as well as the performance of the electrode. Too much oxidation reduces the electrical conductivity of the activated carbon. Facile oxidation by aq. H₂O₂ can be recommended as a practical modification of the surface since it takes place safely below 100°C without releasing any harmful gas.     

Influence of ion assistance on LaF3 films deposited by molybdenum boat evaporation

LaF3 thin films at 193 nm were deposited by the molybdenum boat evaporation with ion-assisted deposition (IAD). Various optical characteristics, stress, and microstructures that formed under different ion-beam voltages of IAD deposition were investigated. The relation between these properties is also discussed. LaF3 films deposited with IAD exhibited small rough surfaces and large optical loss at 193 nm. The largest value of optical loss for films at 193 nm, which were prepared at an ion-beam voltage of 400 V, was 1.55% and the extinction coefficient was smaller than 0.0015. Microstructures and crystalline structures of films were influenced and changed by the ion-assisted deposition process. Tensile stress value of films increased as the ion-beam voltage rose. Refractive index, related to the packing density and microstructures, also increased as the ion-beam voltage rose.     

Force measurement enabling precise analysis by dynamic force spectroscopy

Dynamic force spectroscopy (DFS) makes it possible to investigate specific interactions between two molecules such as ligand-receptor pairs at the single-molecule level. In the DFS method based on the Bell-Evans model, the unbinding force applied to a molecular bond is increased at a constant rate, and the force required to rupture the molecular bond is measured. By analyzing the relationship between the modal rupture force and the logarithm of the loading rate, microscopic potential barrier landscapes and the lifetimes of bonds can be obtained. However, the results obtained, for example, in the case of streptavidin/biotin complexes, have differed among previous studies and some results have been inconsistent with theoretical predictions. In this study, using an atomic force microscopy technique that enables the precise analysis of molecular interactions on the basis of DFS, we investigated the effect of the sampling rate on DFS analysis. The shape of rupture force histograms, for example, was significantly deformed at a sampling rate of 1 kHz in comparison with that of histograms obtained at 100 kHz, indicating the fundamental importance of ensuring suitable experimental conditions for further advances in the DFS method.     

n-Hexyl Laurate and Fourteen Related Fatty Acid Esters: New Secretory Compounds from the Julid Millipede, Anaulaciulus sp.

A total of fifteen saturated fatty acid esters were newly identified from the secretions of an unidentified Anaulaciulus sp. (Julida: Julidae). The fatty acid components of the esters were composed of normal chain acids (from C₁₀ to C₁₄) and of branched chain acids (from iso-C₁₂ to iso-C₁₅ and anteiso-C₁₅). The alcohol moieties were all composed of normal chain alcohols varying from n-butanol to n-octanol. The most abundant component found in the total esters was n-hexyl laurate (64.7%). Novel compounds identified from the millipede secretion extracts include six branched iso- and anteiso-fatty esters, an odd-numbered C₁₁-fatty acid ester, a C₁₃-fatty acid ester, and a C₇-alcohol ester, all of which were previously undescribed natural products. In addition, a characteristic mixture of benzoquinones, such as 2-methyl-1,4-benzoquinone, 2-methoxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, 2-methoxy-6-methyl-1,4-benzoquinone, and 2,3-dimethoxy-5-methyl-1,4-benzoquinone were identified from the secretions, together with trace amounts of 1,4-benzoquinone.     

Introduction of local tensile strain on Ge substrates by SiGe stressors selectively grown on wet chemically recessed regions for strained Ge-nMOSFETs

Introduction of tensile strain into Ge substrates was demonstrated by forming embedded SiGe stressors on the recessed regions formed by an anisotropic wet chemical etching process for strained Ge-nMOSFETs having high electron mobility. A damage-free and well controlled anisotropic wet chemical etching process is developed in order to avoid plasma-induced damages in a conventional RIE process. The uni-axial tensile strain over 1% near the Ge recess-edge regions, which is induced by the embedded SiGe stressors, is also demonstrated for the first time. These results suggest that higher electron mobility than the upper-limit for a Si-MOSFET is obtainable in short channel strained Ge-nMOSFETs with the embedded SiGe stressors.     

活性炭及工艺参数对所制固体活性炭性能的影响

以煤焦油基活性炭(TAC)和椰子壳活性炭(CAC)为原料,以聚乙烯醇缩丁醛(PVB)为粘接剂,以邻苯二甲酸二丁酯(DBP)为增塑剂,通过混合、成型、硬化及炭化处理,最终制得固体活性炭。详细地考查了工艺条件(如强度、收率、收缩率、比表面积等)的影响。研究结果表明对于椰子壳活性炭来说,制备高强度(>5000kPa)的固体活性炭是困难的,其主要原因在于椰子壳活性炭比煤焦油基活性炭含有更少的表面官能团(-COOH,-OH等),而这些官能团可能增强PVB在活性炭表面的粘接,并且参与粘接剂的氧化硬化,硬化的粘接剂在炭化过程中在活性炭颗粒间形成炭桥或者枝状结构而粘接这些颗粒。因此,为了制备高强度的固体活性炭,椰子壳活性炭的表面改性是必要的。     

A study of the electromagnetic vibration of a capacitor induction motor caused by time-harmonic voltages

In recent years, power source voltage waveform distortion has become noticeable, as electrical appliances with rectifier circuits have become widely used. Connecting capacitor inductor motor (CRM) to such distorted supply, or controlling CRM by simple controller with a switching device (such as triacs), harmonic voltage is supplied to CRM. In that case, CRM produces electromagnetic vibrations caused by not only the fundamental voltage but also time-harmonic voltages in the distorted voltage. In addition, CRM produces electromagnetic vibration due to backward magnetic fields. Thus, it is difficult to clarify a relationship between electromagnetic vibration of CRM and harmonic voltages. In this paper, the causes of the electromagnetic vibration of CRM operating under distorted wave supply voltage are discussed. First, a general equation of dominant electromagnetic force waves is shown considering not only forward magnetic fields but also backward magnetic fields. Using a general equation, causes of dominant electromagnetic vibration can be clarified. Next, by discussing in detail some examples of the dominant vibration, the relationship between the vibration and harmonic voltages becomes evident. Furthermore, the relationship between the vibration and backward magnetic field is clarified.     

Investigation of a new extinguishing principle for a gas circuit breaker

A self-extinguishing principle of a gas circuit breaker (GCB) without puffer action (autopuffer GCB) using an external magnetic field was investigated to improve the interrupting capability in the small current region (several kA). Properties of the rotating speed of an arc, the arc voltage, and the gas pressure rise in an expansion space under the external magnetic field were studied experimentally. The relation between the interrupting capability and the radial magnetic flux density in the autopuffer GCB with a permanent magnet (magnet-assisted autopuffer GCB) was obtained experimentally and also analyzed numerically. The results are summarized as follows.

• 1 The arc column is driven in the azimuthal direction by the radial component of the external magnetic field.
• 2 The rotating speed of the arc driven by the radial magnetic field of a permanent magnet remains constant in the arc current range below several kA, and it decreases with an increasing current in the current above several kA.
• 3 Since the arc rotation raises the arc voltage and gas pressure in the expansion space, the gas flow from the expansion space to the arc increases in the vicinity of current zero. The interrupting capability is then improved in the small current region.
• 4 It is confirmed that the magnet-assisted auto-puffer GCB has a good interrupting capability not only for the large current region but also for the small current region.

     

Effects of calcium stearate addition of ultrahigh molecular weight polyethylene in direct compression molding

The effects of calcium stearate addition in molding of ultrahigh molecular weight polyethylene (UHMWPE) were investigated by tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FT‐IR) spectroscopy, and elemental analysis. Four types of UHMWPE specimens with varying contents of calcium stearate (<5, 50, 100, and 1000 ppm) were used in this study. SEM observation revealed that calcium stearate added specimens have smoother and more homogeneous microstructures. After accelerated aging, subsurface oxidative degeneration was observed in all specimens; however, calcium stearate added specimens had less oxidative degeneration in comparison with specimens without additives. Specimens showed better mechanical properties with increasing content of calcium stearate. Though all specimens aggravated their mechanical properties due to oxidation after accelerated aging, the specimens of 100 ppm of calcium stearate showed better properties at 3.7 MPa larger yield strength and four times larger value of elongation at fracture than the specimens without additives. These results indicate that calcium stearate addition produces dense packing of UHMWPE particles, which brings about stronger fusion among the particles and fewer structural defects, and results in better mechanical properties and better resistance to oxidative degeneration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1602–1609, 2003