The potential of local impedance spectroscopy (IS) to access changes in emulsions and foams has been investigated.As test systems we used the separation of a simple oil/vinegar mixture as well as the whipping process of dairy cream.For the latter, IS data were compared to particle size distribution (PSD) measurements.Our measurements show that local IS is indeed a valuable tool to locally study processes in emulsion.On one hand, it seems to be very sensitive to small water quantities in oil thus being a suitable method for process control in water removing processes.On the other hand, concerning fat foams, it seems to be able to detect the evolution of foam structures.Both examples show that local IS could be a helpful tool for process control.

Glass-ceramic materials are increasingly becoming the material of choice in the field of dental prosthetics, as they can feature both high strength and very good aesthetics. It is believed that their color, microstructure and mechanical properties can be tuned such as to achieve an optimal lifelike performance. In order to reach that ultimate perfection a controlled arrangement of amorphous and crystalline phases in the material is required. A phase transformation from amorphous to crystalline is achieved by a heat treatment at defined temperature levels. The traditional approach is to perform the heat treatment in a furnace. This, however, only allows a homogeneous degree of crystallization over the whole volume of the parent glass material.Here a novel approach using a local heat treatment by laser irradiation is presented. To investigate the potential of this approach the crystallization process of SiO2-Li2O-Al2O3-based glass has been studied with laser systems (pulsed and continuous wave) operating at different wavelengths.Our results show the feasibility of gradual and partial crystallization of the base material using continuous laser irradiation. A dental prosthesis machined from an amorphous glassy state can be effectively treated with laser irradiation and crystallized within a confined region of a few millimeters starting from the body surface. Very good aesthetics have been achieved.Preliminary investigation with pulsed nanosecond lasers of a few hundreds nanoseconds pulse width has enabled more refinement of crystallization and possibility to place start of phase change within the material bulk.

In this chapter, the peculiarities of integrating micro-/nano-materials testing within a scanning electron microscope are addressed. The mostly popular techniques are described, including miniaturized tensile tests, compression tests, and nano-indentation tests. Then the subject of image analysis is addressed and, finally a case study combining the use of compressive and tensile testing methods is presented.

Micro-structured dielectric surfaces in combination with electrode structures are promising in the field of rapid prototyping of micro-sensors. In this work laser-induced back side etching and back side deposition using aqueous copper sulfate in form of a tartrate complex with formaldehyde as absorber liquid has been investigated regarding this aim. Results obtained with different laser systems ranging from UV to Near-IR and with pulse lengths from femtoseconds to nanoseconds will be presented, in order to give a wide-spread overview of the different observable effects. Depending on the specific setup and laser parameters, either well-defined compact Cu deposits, micro-or nano-scaled Cu droplets or ablation of the dielectric substrate was observed. Best quality crystalline and conducting Cu structures were achieved using ns pulses at 532 nm wavelength. Droplet formation with UV excimer laser was observed. Parameters influencing each configuration will be discussed.

Cost-efficient machining of dielectric surfaces with high-precision and low-roughness for industrial applications is still challenging if using laser-patterning processes. Laser induced back side wet etching (LIBWE) using UV laser pulses with liquid heavy metals or aromatic hydrocarbons as absorber allows the fabrication of well-defined, nm precise, free-form surfaces with low surface roughness, e. g., needed for optical applications. The copper-sulphate-based absorber CuSO4/K-Na-Tartrate/NaOH/formaldehyde in water is used for laser-induced deposition of copper. If this absorber can also be used as precursor for laser-induced ablation, promising industrial applications combining surface structuring and deposition within the same setup could be possible. The etching results applying a KrF excimer (248 nm, 25 ns) and a Nd:YAG (1064 nm, 20 ns) laser are compared. The topography of the etched surfaces were analyzed by scanning electron microscopy (SEM), white light interferometry (WLI) as well as laser scanning microscopy (LSM). The chemical composition of the irradiated surface was studied by energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). For the discussion of the etching mechanism the laser-induced heating was simulated with finite element method (FEM). The results indicate that the UV and IR radiation allows micro structuring of fused silica with the copper-based absorber where the etching process can be explained by the laser-induced formation of a copper-based absorber layer.

Knowing the optical properties of metals in solid and liquid phase is important for understanding and optimizing material processing. But it is difficult to find reliable data, especially for the wavelength range in the near-infrared. Further there are several approaches of extending the Drude-model for optical properties of metals including temperature dependency and intra-band absorption, which can describe the qualitatively behavior of optical properties as a function of temperature and wavelength. Although these extended models can predict accurately the optical properties for some specific metals and wavelengths, in general they fail to predict accurate values. Comparing our own experimental results of gold and silver in the solid and liquid phase at near-infrared with extended Drude-models has revealed that even a combined extended Drude-model taking temperature dependency, anomalous skin effect and intra-band absorption into account, cannot predict the optical properties accurately. In general the temperature dependency of the optical properties of metals is much weaker than predicted by the various models. Additionally analyzing the refractive index and absorption coefficient of metals at 1.06μm and 10.6μm has shown a difference of approximately a factor of 10 between 1.06μm and 10.6μm causing a sharp absorption peak at 10.6μm compared to a broaden peak at 1.06μm. This factor of 10 is much larger than the difference of the optical properties between the solid and the liquid phase and has a great influence on the laser energy distribution absorbed in the metal during laser processing.

Fibre deformations such as kinks and micro-compressions are significant parameters in determining the quality of industrial pulps. Undoubtedly, very little information has been obtained so far on fibre deformation because it is very tedious to handle the specimens. In this study, a novel in situ scanning electron microscope (SEM) micro-indentation technique was adopted for the first time to study the deformation of single industrial pulp fibres in the transverse direction. A one-to-one correspondence between load drops in load-displacement curve and cell wall deformation was obtained by using the SEM video sequence recorded during micro-indentation. The cell wall deformation occurred by 'elastic' sinking-in and lateral bulging of the microfibrils. Finally, the critical load (stress) required to initiate a crack in the cell wall was measured for different unbleached pulp fibres.

Unrefined chemical pulps of bleached and unbleached softwood (Scots pine, Pinus sylvestris) and hardwood (Eucalyptus, Eucalyptus globulus) were subjected to indentation tests using a nanoindenter equipped with an AFM scanner. Tests on unbleached pulps revealed no difference in hardness values between softwood and hardwood, but bleaching treatment decreased the hardness values of both pulps. Indentation modulus of 12 GPa was observed for unbleached softwood pulps, which is 25% higher than unbleached hardwood pulps. Bleaching treatment again decreased the indentation modulus of the softwood pulps, whereas it slightly increased the indentation modulus of the hardwood pulps. After bleaching and drying processes, only negligible difference was observed in cell wall mechanical properties (hardness and indentation modulus) between hardwood and softwood pulps. This study is based on latewood pulp fibres.

weaker than in the case of healthy ears. In the present analysis of measured emissions documented in the literature, it is shown that the time-dependence of the instantaneous frequency of the emissions is consistent with a cochlear model (1) involving two resonators, namely the IOCR (internal organ-of-Corti resonator; spring = OHCs and surrounding structures) and the BMR (basilar-membrane resonator; spring = fibres of the BM). At a given distance-from-base in the basal half of the BM, the resonance frequency of the IOCR is lower than that of the BMR by about one octave. The IOCR is thought to enable, during a sine-tone, the OHCs to feed mechanical energy into the cochlear travelling wave and thus to give rise to the "active" response peak. That OHC-generated mechanical energy is conjectured to cause the oto-acoustic emissions.

The purpose of this article is to present the design and capabilities of two in situ scanning electron. microscope (SEM) indentation instruments covering a large load range from mu N to N. The capabilities and advantages of in situ SEM indentation are illustrated by two applications: indentation of a thin film and a nanowire. All the experiments were performed on electrodeposited cobalt, whose outstanding magnetic properties make it a candidate material for MEMS and NEMS devices. Microsc. Res. Tech. 72:242-249, 2009. (C) 2009 Wiley-Liss, Inc.

Cellulose fibril aggregates embedded in a lignin matrix in the cell wall are a predominant reason for the outstanding specific tensile strength of wood. In order to convert these mechanical properties to practical use for polymer composites, the fibrils can be isolated out of sulphite pulp. The obtained fibrils have diameters below 100 nanometer and lengths in the micrometer range. Homogeneous, translucent fibril films and polymer composites with hydroxypropyl cellulose can be prepared. For mechanical characterization tensile tests and nanoindentation experiments were carried out. The addition of fibrils led to an up to three times higher modulus of elasticity and an up to five times higher tensile strength of the polymers. Network formation was identified by Transmission Electron and Atomic Force Microscopy in films with a filling ratio of at least 10 %. The perspectives of producing new bio-based nanomaterials are promising. (c) 2006 American Chemical Society.