Laser triangulation measurements of Er:YAG and Er,Cr:YSGG laser-ablated volumes in hard dental tissues are made, in order to verify the possible existence of a "hydrokinetic" effect that has been proposed as an alternative to the "subsurface water expansion" mechanism for hard-tissue laser ablation. No evidence of the hydrokinetic effect could be observed under a broad range of tested laser parameters and water cooling conditions. On the contrary, the application of water spray during laser exposure of hard dental material is observed to diminish the laser-ablation efficiency (AE) in comparison with laser exposure under the absence of water spray. Our findings are in agreement with the generally accepted principle of action for erbium laser ablation, which is based on fast subsurface expansion of laser-heated water trapped within the interstitial structure of hard dental tissues. Our measurements also show that the well-known phenomenon of ablation stalling, during a series of consecutive laser pulses, can primarily be attributed to the blocking of laser light by the loosely bound and recondensed desiccated minerals that collect on the tooth surface during and following laser ablation. In addition to the prevention of tooth bulk temperature buildup, a positive function of the water spray that is typically used with erbium dental lasers is to rehydrate these minerals, and thus sustaining the subsurface expansion ablation process. A negative side effect of using a continuous water spray is that the AE gets reduced due to the laser light being partially absorbed in the water-spray particles above the tooth and in the collected water pool on the tooth surface. Finally, no evidence of the influence of the water absorption shift on the hypothesized increase in the AE of the Er,Cr:YSGG wavelength is observed.

A new method for measuring the time-dependent displacement and deformation of electrodes during resistance spot welding (RSW) is described. The method allows assessment of the non-stationary thermal expansion of the electrodes. By measuring the electrode indentation close to the weld-piece surface, the method enables a better estimation of indentation than the present methods that rely on measurement of the displacement of the outside part of the electrodes or their holders. The method is based on using a digital video camera to acquire image sequences of electrode caps in the RSW process. A regular pattern of shallow bores is drilled into the caps to enhance the contrast of the acquired images and facilitate image processing. The distances between the bores are analyzed from the image sequences to determine the temporally and spatially resolved displacement and deformation of the caps. The analysis revealed that the cap deformations in some welding regimes can reach up to 20% of the maximum cap displacements, which are approximately 200 µm. The employed image processing algorithms are presented as well as examples of results that demonstrate the applicability of the method.

This paper presents a newly developed innovative dissolution apparatus with the ability to combine a special pattern of movement, closely mimicking the peristaltic contractions of the human stomach, and the gastric emptying process. The main benefits of the advanced gastric simulator (AGS) are the close physical similarities (shape, volume, and inner wall structure) to the human stomach. The fluid volume, gastric flow, and medium composition can be closely matched to actual in vivo conditions. Moreover, the soft AGS wall is surrounded by a series of constriction mechanisms, which produce the mechanical forces necessary to create the hydrodynamic conditions and physical pressure on its contents aimed at replicating the in vivo conditions. The gastric emptying is enabled by a unique feature, a custom pylorus, which controls the flow of fluids out of the container. Tablets containing a biopharmaceutics classification system (BCS) class III drug were tested to show the applicability of this model. Experiments were performed with the AGS utilizing a United States Pharmacopoeia (USP) apparatus 2. Results demonstrated that mechanical influences on the dosage form in the AGS could be varied by changing the programs of the constriction mechanisms and the settings of the simulated pylorus. The model parameters can be successfully controlled to influence the drug release kinetics.

Remote object geolocation is a process of determining the geographic location of distant objects, which is often required in geology, military applications, surveying and elsewhere. Unlike in the case of widely used satellite localization and navigation solutions, there are very few studies of the measurement uncertainties and their propagation in the case of geolocating distant, non-cooperative objects. To investigate this specific segment of navigation we developed an experimental system built entirely of COTS (Commercial Of-The-Shelf) components. The aim of this work is to study the possibility for assessing the measurement characteristics of such integrated systems, based on the specified uncertainties of the individual measuring devices.

The selection of the material regarding specific design of the stern tube journal bearings in vessels is critical taking into account the lubrication system, whether oil or water based, and the consequent lubricant leakage. Therefore, the present study examines the feasibility and the advantages of implementing water lubricated polymer shaft bearings instead of conventional white metal bearings lubricated by oil. The investigation method is related to the numerical model and the software application based on finite difference method and isoviscous model. Results, based upon data collected from three different types of actual vessels in service, have shown that power loss in polymer bearings is at least 6 times less than in conventional white metal ones indicating that polymer journal bearings are significantly more energy efficient and environmentally friendly.