Design, Synthesis and Preliminary Evaluation of the Cytotoxicity and Antibacterial Activity of Novel Triphenylphosphonium Derivatives of Betulin.

For several decades, natural products have been widely researched and their native scaffolds are the basis for the design and synthesis of new potential therapeutic agents. Betulin is an interesting biologically attractive natural parent molecule with a high safety profile and can easily undergo a variety of structural modifications. Herein, we describe the synthesis of new molecular hybrids of betulin via covalent linkage with an alkyltriphenylphosphonium moiety.

Assessment of Local Dynamic Stability in Gait Based on Univariate and Multivariate Time Series.

The ability of the locomotor system to maintain continuous walking despite very small external or internal disturbances is called local dynamic stability (LDS). The importance of the LDS requires constantly working on different aspects of its assessment method which is based on the short-term largest Lyapunov exponent (LLE). A state space structure is a vital aspect of the LDS assessment because the algorithm of the LLE computation for experimental data requires a reconstruction of a state space trajectory.

Contact atomic force microscopy using piezoresistive cantilevers in load force modulation mode.

Scanning probe microscopy (SPM) encompasses several techniques for imaging of the physical and chemical material properties at nanoscale. The scanning process is based on the detection of the deflection of the cantilever, which is caused by near field interactions, while the tip runs over the sample's surface. The variety of deflection detection methods including optical, piezoresistive, piezoelectric technologies has been developed and applied depending on the measurement mode and measurement environment.

Metrology of electromagnetic static actuation of MEMS microbridge using atomic force microscopy.

The objective of this paper is to describe application of atomic force microscopy (AFM) for characterization and calibration of static deflection of electromagnetically and/or thermally actuated micro-electromechanical (MEMS) bridge. The investigated MEMS structure is formed by a silicon nitride bridge and a thin film metal path enabling electromagnetic and/or thermal deflection actuation. We present how static microbridge deflection can be measured using contact mode AFM technology with resolution of 0.

Carrier density distribution in silicon nanowires investigated by scanning thermal microscopy and Kelvin probe force microscopy.

The use of scanning thermal microscopy (SThM) and Kelvin probe force microscopy (KPFM) to investigate silicon nanowires (SiNWs) is presented. SThM allows imaging of temperature distribution at the nanoscale, while KPFM images the potential distribution with AFM-related ultra-high spatial resolution. Both techniques are therefore suitable for imaging the resistance distribution.

Substance P and intensity of pruritus in hemodialysis and peritoneal dialysis patients.

Background: Uremic pruritus is a common complication in patients undergoing dialysis. The pathophysiological mechanisms of pruritus in patients with end-stage renal disease remain unknown. Neuropeptides, including substance P, are postulated to play an important role in the pathogenesis of pruritus.

Expanded beam deflection method for simultaneous measurement of displacement and vibrations of multiple microcantilevers.

Here we present an extension of optical beam deflection (OBD) method for measuring displacement and vibrations of an array of microcantilevers. Instead of focusing on the cantilever, the optical beam is either focused above or below the cantilever array, or focused only in the axis parallel to the cantilevers length, allowing a wide optical line to span multiple cantilevers in the array. Each cantilever reflects a part of the incident beam, which is then directed onto a photodiode array detector in a manner allowing distinguishing between individual beams.

Buried amorphous-layer impact on dislocation densities in silicon.

The impact of amorphous layers on dislocation densities in silicon piezo-resistors was investigated by means of transmission electron microscopy and chemical etching. Mechanical bevel polishing at a shallow angle and selective etching were applied to assess the dislocation depth distributions. It was found that, despite the presence of additional defects after recrystallization, the initial presence of a buried amorphous layer reduced, after annealing, the dislocation density in the depletion region of a p-n junction, compared with the case of a shallower, surface amorphous layer.

Microsystem technology as a road from macro to nanoworld.

Tremendous progress of microelectronic technology observed within last 40 years is closely related to even more remarkable progress of technological tools. It is important to note however, that these new tools may be used for fabrication of diverse multifunctional structures as well. Such devices, called MEMS (Micro-Electro-Mechanical-System) and MOEMS (Micro-Electro-Opto-Mechanical-System) integrate microelectronic and micromechanical structures in one system enabling interdisciplinary application, with most interesting and prospective being bio-medical investigations.

Calibration and examination of piezoresistive Wheatstone bridge cantilevers for scanning probe microscopy.

This paper describes the method of determining the force constant and displacement sensitivity of piezoresistive Wheatstone bridge cantilevers applied in scanning probe microscopy (SPM). In the procedure presented here, the force constant for beams with various geometry is determined based on resonance frequency measurement. The displacement sensitivity is measured by the deflection of the cantilever with the calibrated piezoactuator stage.

Piezoresistive sensors for scanning probe microscopy.

In this article we summarize the efforts devoted to the realization of our ideas of the development of piezoresistive sensor family used in scanning probe microscopy. All the sensors described here are fabricated based on advanced silicon micromachining and standard CMOS processing. The fabrication scenario presented in this article allows for the production of different sensors with the same tip deflection piezoresistive detection scheme.