Substrate Integrated Waveguide Cavity Resonators for Complex Permittivity Characterization of Materials

A novel planar substrate integrated waveguide cavity resonator technique for measurement of complex permittivity is described, which has applications for dielectric measurement systems in the pharmaceutical industry. The high-Q resonant structure is a modernization of well-known measurement cells where the dielectric constant is deduced by cavity perturbation from the shift in resonant frequency and the change in the Q factor. The method uses extremely small amounts of a broad range of materials for accurate characterization. The ease of fabrication, low cost, and potential for integration with many other components on the same substrate allows it to be used in a disposable manner.     

Evaluation of colloidal silica suspension as efficient additive for improving physicochemical and in vitro biological properties of calcium sulfate-based nanocomposite bone cement

In the present study new calcium sulfate-based nanocomposite bone cement with improved physicochemical and biological properties was developed. The powder component of the cement consists of 60 wt% α-calcium sulfate hemihydrate and 40 wt% biomimetically synthesized apatite, while the liquid component consists of an aqueous colloidal silica suspension (20 wt%). In this study, the above mentioned powder phase was mixed with distilled water to prepare a calcium sulfate/nanoapatite composite without any additive. Structural properties, setting time, compressive strength, in vitro bioactivity and cellular properties of the cements were investigated by appropriate techniques. From X-ray diffractometer analysis, except gypsum and apatite, no further phases were found in both silica-containing and silica-free cements. The results showed that both setting time and compressive strength of the calcium sulfate/nanoapatite cement improved by using colloidal silica suspension as cement liquid. Meanwhile, the condensed phase produced from the polymerization process of colloidal silica filled the micropores of the microstructure and covered rodlike gypsum crystals and thus controlled cement disintegration in simulated body fluid. Additionally, formation of apatite layer was favored on the surfaces of the new cement while no apatite precipitation was observed for the cement prepared by distilled water. In this study, it was also revealed that the number of viable osteosarcoma cells cultured with extracts of both cements were comparable, while silica-containing cement increased alkaline phosphatase activity of the cells. These results suggest that the developed cement may be a suitable bone filling material after well passing of the corresponding in vivo tests.     

Physico-chemical and in vitro biological evaluation of strontium/calcium silicophosphate glass

Strontium is known to reduce bone resorption and stimulate bone formation. Incorporation of strontium into calcium phosphate bioceramics has been widely reported. In this work, calcium and calcium/strontium silicophosphate glasses were synthesized from the sol–gel process and their rheological, thermal, and in vitro biological properties were studied and compared to each other. The results showed that the gel viscosity and thus the rate of gel formation increased by using strontium in glass composition and by increasing aging temperature. In strontium-containing glass, the crystallization temperature increased and the type of the crystallized phase was different to that of strontium-free glass. Both glasses favored precipitation of calcium phosphate layer when they were soaked in simulated body fluid; however strontium seemed to retard the rate of precipitation slightly. The in vitro biodegradation rate of the strontium/calcium silicophosphate glass was higher than that of strontium-free one. The cell culture experiments carried out using rat calvaria osteoblasts showed that the incorporation of strontium into the glass composition stimulated proliferation of the cells and enhanced their alkaline phosphatase activity, depending on cell culture period.     

On the Relationship of Sample Size and Moments of Estimators in Simple Linear Regression

Methods are developed for determining minimum sample size in simple linear regression (when residuals are nonnormal) that permit use of the classical normality-based analyses. The methods are based on behavior of standardized third and fourth moments of regression estimators. The case of symmetric independent variable values with one observation at each is considered. All other regression assumptions are assumed to be true.     

Expression profile of T cell associated molecules in the interfacial tissue of aseptically loosened prosthetic joints

The involvement of T cells in the progression of inflammation in response to wear debris at the interface of aseptically loosened joints is currently undefined. This cell type has repeatedly been demonstrated to be a common component of the cellular membrane, the interface, which forms between the bone and implant of total joint replacements (TJRs) [1, 2]. Three further insights into the role of this cell type in the interface were investigated here. Immunostaining demonstrated CD4 expression in 80% of the 15 cases tested while CD8 expression was present in 60% of the cases. Polymerase chain reaction (PCR) detected IFN- mRNA expression in 75% of eight cases tested; in contrast IL-10 mRNA was only demonstrated in 50% of these same cases. Proteins extracted from another eight cases of revision tissue were analyzed using Western blotting for IL-17, fractalkine (Fkn) and CD40. IL-17 and Fkn were a consistent feature of all cases tested (8/8), while CD40 was undetectable in one case (7/8). These results show that T cells present in the interface are more commonly of the helper T cell phenotype, although cytotoxic T cells are also present. Helper T cells (Th) are responsible for the polarization of the immune response through their production of key mediators. The PCR results obtained in this study suggest that a Th1 response characterized by the production of IFN- predominates over the Th2, IL-10 mediated response. Furthermore the demonstration of the expression of IL-17, Fkn and CD40, all of which are Th1 associated molecules, supports this conclusion.     

Multi-Modal Interaction of Human and Home Robot in the Context of Room Map Generation

In robotics, the idea of human and robot interaction is receiving a lot of attention lately. In this paper, we describe a multi-modal system for generating a map of the environment through interaction of a human and home robot. This system enables people to teach a newcomer robot different attributes of objects and places in the room through speech commands and hand gestures. The robot learns about size, position, and topological relations between objects, and produces a map of the room based on knowledge learned through communication with the human. The developed system consists of several sections including: natural language processing, posture recognition, object localization and map generation. This system combines multiple sources of information and model matching to detect and track a human hand so that the user can point toward an object of interest and guide the robot to either go near it or to locate that object's position in the room. The positions of objects in the room are located by monocular camera vision and depth from focus method.     

Influence of the valve lubricant on the aerodynamic particle size of a metered dose inhaler

Presented in this work are the results of a study designed to investigate the impact of valve lubricant (i.e., silicone oil) on the aerodynamic particle size distribution (PSD) of a steroid suspension metered dose inhaler (MDI) containing propellant HFA-227. The objective of this study was to explore whether the valve lubricant, which is often used in MDI products to prevent valve sticking, can enter an MDI product and potentially impact the aerosol spray dynamics. The results of this work have shown that samples containing valves with high silicone levels produced a larger aerodynamic particle size (by cascade impaction) than samples with low-silicone or silicone-free valves. It is postulated that the presence of silicone in the product may increase the propensity for drug aggregation, thereby leading to an increase in the aerodynamic particle size of the emitted aerosol. These findings stress the importance of evaluating the effects of valve lubricant on the aerodynamic PSD in the early formulation development stage of an MDI.     

Entry port selection for detecting particle size differences in metered dose inhaler formulations using cascade impaction

Different sized glass entry ports were evaluated for their drug collection efficiency during aerodynamic particle sizing of metered dose inhalers (MDIs) using cascade impaction. A comparison was made between collection efficiency in the entry port, impactor plates, and filter using the 1 L, 2 L, and 20 L glass entry ports and the USP and twin impinger entry ports. Entry port losses were dependent on the size of entry port selected, with 1-2 L ports showing optimal recovery on impactor plates, compared to the USP entry port. The 1 L entry port was further compared with the USP entry port in its ability to discriminate between subtle changes in particle size distribution (PSD) in an investigational hydrofluoroalkane (HFA)-based MDI formulation. Deliberately induced differences during product manufacture were easily detected using the 1 L entry port with the Andersen cascade impactor. The USP port was unable to distinguish among products with small particle size differences. An alternative entry port such as the 1 L glass entry port used in this study may provide better means of characterizing the PSD during formulation development and stability testing of MDIs.     

Influence of the size of micronized active pharmaceutical ingredient on the aerodynamic particle size and stability of a metered dose inhaler

Pharmaceutical inhalers are often used to treat pulmonary diseases. Only active pharmaceutical ingredient (API) particles from these inhalers that are less than approximately 5 microm are likely to reach the lung and be efficacious. This study was designed to investigate the impact of micronized API particle size on the aerodynamic particle size distribution (PSD) profile and the particle size stability of a suspension metered dose inhaler (MDI) containing propellant HFA-227 (1,1,1,2,3,3,3 heptafluoropropane) and a corticosteroid. The median API particle size ranged from 1.1 microm to 1.8 microm (97% to 70% of particles <3 microm, respectively). This study showed that increasing the particle size of the API used to manufacture a suspension MDI product increased the aerodynamic PSD of the MDI product. Furthermore, upon storage of the MDI product under temperature cycling conditions, samples containing larger-size API particles were less stable with respect to their aerodynamic PSD than those with smaller-size API particles. It was found that size-dependent particle growth and/or aggregation of the suspended API may be occurring as a result of temperature cycling. In conclusion, this study has shown that the particle size of the raw API impacts the properties and stability of the emitted aerosol spray. Based on the findings from this study, it is recommended that the API particle size be carefully controlled in order to meet specifications set for the finished MDI product.     

DFB Lasers With Deeply Etched Vertical Grating Based on InAs–InP Quantum-Dash Structures

Distributed feedback lasers with first-order vertical grating based on AlInGaAs-InAs-InP quantum-dash lasers were fabricated by electron beam lithography and Cl₂-Ar reactive ion etching with an electron cyclotron resonance source. Low threshold currents and single-mode operation with sidemode suppression ratios of 48 dB and a direct modulation bandwidth of 5.5 GHz were demonstrated