Use of dynamic electronic speckle pattern interferometry with the Hilbert transform method to investigate thermal expansion of a joint material

A dynamic electronic speckle pattern interferometry method is applied to investigate thermal expansion of a joint material (ceramic-stainless steel) as a practical industrial object. The speckle interference signal is considered in the temporal domain and the phase is analyzed by the Hilbert transform method. Errors caused by the bias and modulation variations over the phase values are first examined by numerical simulation. Two experiments are performed with in-plane and out-of-plane sensitive systems to study the 3D deformation field thoroughly. The deformation field showed clearly the difference between the thermal expansions of the stainless steel and ceramic. It was also revealed that the boundary of materials and its vicinity suffer very large thermal strain due to the significantly large difference in the linear coefficient of thermal expansions.     

Handling of fine-particles by time-averaged particle driving method in plasmas

We developed a noble technique for the fine-particle handling in plasmas. In this method a pair of point electrodes are introduced in the plasma, to which positive pulses are applied alternatively. When the pulse repetition period is shorter than the particle response time, the particles feel only time-averaged force because of their large mass. Spatial profile of the equivalent potential of the time-averaged force varies from a circle to an ellipse with an increase in the local discharge at the electrodes. The particles are eventually transported toward a middle point between two point-electrodes, being almost independent of their initial positions. This method is quite effective for converging fine particles in the plasma.     

Hydrodynamics of Superfluid Bose Gases in an Optical Lattice at Finite Temperatures

Starting from an effective action for the order parameter field, we derive a coupled set of generalized hydrodynamic equations for a Bose condensate in an optical lattice at finite temperatures. Using the linearized hydrodynamic equations, we study the microscopic mechanism of the Landau instability due to the collisional damping process between the condensate and noncondensate atoms. It is shown that the Landau criterion for the stability of a superfluid in a uniform system is modified due to the presence of the periodic optical lattice potential.     

Visualizing vitreous using quantum dots as imaging agents

Vitreous is transparent tissue located between the lens and the retina of the eye, thus, difficult to look at by even ophthalmological microscope. But vitreous is connected with some sight-threatening eye diseases, for example, retinal detachment, macular hole, epi-retinal membrane, and so forth. Quantum dots (QDs) have been applied to a wide range of biological studies by taking advantage of their fluorescence properties. We established a novel technique of aqueous colloidal QD (ACQD) as a vitreous lesion detector. When compared with some conventional dyes used for clinical situation, i.e. fluorescein, indocyanine green, and triamcinolone acetonide, ACQD exerted a higher performance to detect a Weiss Ring. Furthermore ACQD is also effective to perform vitrectomy, an eye surgery to cut and eliminate vitreous. Some functional structures in vitreous are detected clearly when ACQD was injected into an enucleated porcine eye. We demonstrated that ACQD enabled any ophthalmic surgeon to perform vitrectomy reliably, easily, and more safely. Taken together, the ACQD-oriented vitreous staining system will promote ophthalmological science, and it will raise the cure rate of eye diseases     

Carbon nanotube growth from semiconductor nanoparticles

Nanoscale metal catalysts have been indispensable for carbon nanotube (CNT) synthesis by chemical vapor deposition (CVD). We show that even semiconductor nanoparicles of SiC, Ge, and Si produce single-walled and double-walled CNTs in CVD with ethanol. This implies that nanosize structures might act as a template for the formation of CNT caps composed of five- and six-membered rings. Providing a template for cap formation is the essential role of the catalysts.     

Synthesis and Electrochemical Behavior of Regioisomeric Bismethanofullerene Derivatives

A series of regioisomeric bis-methanofullerenes (diethyl [60]fullerenobisacetate) were prepared by reaction of the sulfonium ylide with C₆₀. Seven stable resultant regioisomers were completely isolated on a preparative HPLC and identified by FT-IR, UV-vis, TOF-MS, and ¹H and ¹³C NMR measurements. The structures of these bisadducts were assigned based on 1) the relationship of the polarities of the regioisomers with the elution order from HPLC; 2) a comparison of their UV-vis spectra with those of corresponding Bingel-Hirsch bisadducts; and 3) the identification of their molecular symmetries by their ¹H and ¹³C NMR spectra. The electrochemical properties of the resultant regioisomeric bismethanofullerene, derivatives were investigated through cyclic voltammetry (CV). The bisadducts exhibited more negative reduction potential than the pristine C₆₀. Trans-2- and cis-3- bisadducts had the least negative potential E¹_1/2 of all the other bisadducts.     

Atomic Layer Epitaxy of Silicon

Two methods are proposed and demonstrated successfully for low temperature atomic layer epitaxy (ALE) of Si, where H atoms play essential roles. The first method is the use of H as a self-limiting factor. Trisilane (Si₃H₈) was used as source gas and the substrate temperature was modulated in order to alternate steps in an ALE cycle. When the temperature was less than 380°C in the adsorption step and more than 520°C in the desorption step, respectively, the grown layer thickness per cycle was 0.8 ML/cycle. The second method is the use of atomic H as an active reducer of a self-limiting factor. A clean surface was exposed to dichlorosilane (SiH₂Cl₂) as source gas to grow an Si monolayer covered with CI. Next, atomic H was injected to reduce CI from the surface. An ideal monolayer growth was obtained with the substrate temperature over 540°C.     

Near-infrared spectroscopic monitoring of the diffusion process of deuterium-labeled molecules in wood. Part I: softwood

The diffusion process of several molecules (D2O, n-butanol (OD) and t-butanol (OD)) in softwood (Sitka spruce) was investigated by means of a deuterium exchange method and Fourier transform near-infrared (FT-NIR) polarization spectroscopy. The location of OH groups in different states of order of cellulose in wood was clarified by analyzing the FT-NIR transmission spectra ranging from 7200 to 6000 cm(-1). Four absorption bands were assigned to 2 x v(OH) absorptions of the amorphous regions, OH groups in semi-crystalline regions, and two types of intramolecular hydrogen-bonded OH groups in the crystalline regions, respectively. The saturation level of accessibility was very different for these absorption bands (i.e., 70-80, 60, and 40-50% for the amorphous, semi-crystalline, and crystalline regions, respectively). However, the saturation accessibilities for each absorption band varied little with molecular structure and geometry of the diffusants. The diffusion rate of D2O was much faster than that of n-butanol (OD) and t-butanol (OD) for all states of orders. The size effect of the butanols led to slight differences in the diffusive transport in the crystalline regions.     

Structural change of water with solutes and temperature up to 100 degrees C in aqueous solutions as revealed by attenuated total reflectance infrared spectroscopy

The attenuated total reflectance infrared (ATR-IR) spectra of several aqueous solutions have been measured by using a newly developed heatable rod-type ATR cell. The OH stretching bands showed systematic change with increasing solute concentrations and these changes can be explained by four different OH components based on curve-fitting results. NaCl solutions show longer H-bond distance character, while carbonate solutions present shorter ones. The Na2CO3 1 M solution conserves this shorter H-bond nature up to 100 degrees C. On the other hand, the loose nature of NaCl solutions becomes less pronounced at higher temperatures because of the dissociation of pure water clusters. These in situ observations of water structures are generally in agreement with the expected nature of fluids within the earth.     

A discussion on major factors affecting crack path of concrete-to-concrete interfacial surfaces

This paper elaborates major factors affecting the crack path of concrete-to-concrete interfacial surfaces produced with placing joint. Eleven types of specimens were employed for the evaluation of tension softening diagram followed by surface observation of the ligament after fracture test. The surface analysis revealed that the layer of Ca(OH)₂ plays a primary role on the crack path. The authors discuss the relationship between fracture mechanics parameters and the ratio of fractured part which excludes detached part in the ligament. The mechanism for determining crack path near concrete-to-concrete interface is proposed using ‘scattered hole model’.