42 research outputs found
Microbial inactivation properties of a new antimicrobial/antithrombotic catheter lock solution (citrate/methylene blue/parabens)
Background. Microbial infections are the most serious complications associated with indwelling central venous catheters. A catheter lock solution that is both antibacterial and antithrombotic is needed. The goal of this study was to determine whether a new catheter lock solution containing citrate, methylene blue and parabens has antimicrobial properties against planktonic bacteria and against sessile bacteria within a biofilm. These effects were compared to the antimicrobial properties of heparin at 2500 units/ml
Expression of a fungal manganese peroxidase in Escherichia coli: a comparison between the soluble and refolded enzymes
Determination of Parameters of Surface Acoustic Wave Vibration Sensors with the Help of Gravitational Field
This work presents results of experimental tests of surface acoustic wave vibration sensor. Measurements of the static sensitivity, resonance frequency, frequency amplitude characteristics and linearity were carried out. Measurements were carried out with the help of the acceleration of gravity and a digital oscilloscope
Surface Acoustic Wave Vibration Sensors for Linear Electronic Warning Systems
The topic of the paper is analysis of feasibility of surface acoustic wave vibration sensors for linear electronic warning systems. In linear warning systems localisation of the object is realised by pointing out the sensors which detect vibrations caused by the object. The information sent out by the detector enables identification of the sensor and its state. The sensor contains surface acoustic wave delay line in four-terminal network. The delay line is formed at the surface of piezoelectric plate. The vibrations of the plate are caused by vibrations of the medium surrounding the sensor. The frequency of the input signal is equal to the working frequency of delay line. The phase of the output signal is shifted in comparison with the input signal. The frequency of the phase shift would be equal to the resonance frequency of the sensor plate. The change of the output signal amplitude would be proportional to the amplitude of plate vibrations. The measured amplitude and frequency of the output signal would be registered by simple electronic devices. The measurements give us knowledge which sensor vibrates and the intensity of these vibrations. Such sensors enable construction of the electronic warning system
Electronic Warning System Based on Surface Acoustic Wave Vibration Sensors
In the paper feasibility analysis of the surface acoustic wave based electronic warning system was presented. As a transducer in the system the surface acoustic wave delay line was proposed. It is fabricated in standard single mask process as a pair of interdigital transducers placed on the top of piezoelectric crystal substrate. Transducer is a plate with rectangular cross-section and it converts all environmental vibration to electric signal. From electronic point of view it was considered as a two-port network. Necessary condition for proper sensor operation is that the input signal frequency from external generator should be close to central frequency of delay line. Principle of operation of the sensor is that the measured phase shift of high frequency signal has frequency equal resonant frequency of vibrating plate and its amplitude is proportional to vibration amplitude of transducer. The environmental vibrations are defined by amplitude of the output signal and the threat location is pointed by resonant frequency of excited transducer. The described above principles of sensor operation allow us designing electronic warning system consisting of many sensors with different resonant frequencies of transducers. Output signals from precisely located sensors contain all necessary information about the whole warning system. This information is easy to transmit and detect by simple electronic circuits based on phase detector and proper data acquisition system, for which necessary conditions are presented
Electroglottographic assessment of the results of medical treatment of patients with vocal cords polyps
The subject matter of this paper is a multileyered objective analysis of extipartion phonomicrosurgery in treatment of benign vocal cords lesions, assessed in electroglottographic examinations. A group of 26 patients with benign larynx lesions were included in a prospective clinical trial. All phonomicrosurgery procedures were conducted at the Department of Otolaryngology at the CM UJ in Kraków. For electroglottographic analysis the following were used: mean irregularity factor for the word "ola", and the voice profile for the vowel "a" using the mean parameter of glottis closure Qx - mean, mean frequency of glottis tone - Fx mean, Jitter factor first mean and Schimmer factor plus mean. In electroglottographic assessment after the phonomicrosurgical procedures stable improvement of the phonation function of larynx. This trial proved the usefulness of the electroglottographic examinations for the multi-layered analysis of the phonation function of glottis in diagnosis and treatment of patients suffering from vocal cords polyps
Analysis of Experimental Stand for Surface Acoustic Wave Vibrations Sensors
The analysis of vibrations excitation in surface acoustic wave vibrations sensors is the aim of our work. The sensors are parts of electronic warning system which is intended to be mounted at fences of guarded object. The vibration excitation with expected acceleration is needed during experiments. Elements of fences are replaced by tense strings for experimental purposes and the surface acoustic wave vibration sensors are fastened to these strings. Analysis of the assembly string-sensor takes into account not only the mass of sensor but its moment of inertia, too. Free vibrations of string-sensor assembly are considered. The standard excitation by pulling off string in chosen point causes vibrations. The normal vibrations of assembly (frequencies, orthogonal set of normal functions) are calculated and used for calculations of free vibrations. The spectrum of the standard free vibrations is calculated. The results will be used in the experimental stand. The calculations enable excitation of vibrations with expected spectrum. The stand enables tests of the whole warning system. The thresholds of detection and reaction at concurrent intruder alarm will be investigated at this laboratory stand
SAW Delay Line for Vibration Sensors
The paper presents an analysis of surface acoustic wave delay line. The line consists of two simple interdigital transducers placed on a ST-cut quartz plate. Mid-band operation frequency of the line is 74 MHz. The line will be applied for surface acoustic wave vibration sensor. At the immovable end of the plate there are electric signal feeds to both transducers. This is the cause of increase in signal value going directly between the transducers and the cause of line losses. By means of equivalent electric model of interdigital transducer a loss analysis of the line has been made at 50 Ω load. The analysis allows to minimize line losses by matching the transducers to 50 Ω impedance. This has been practically achieved by a design of transducer geometry and configuration matching 50 Ω impedance, by means of inductance. An analysis of repeated operation characteristics of two interdigital transducers has been made. A signal going directly through capacitance between transducers and signals reflected from the edge of piezoelectric substrate have been presented. Results of theoretical analysis have been compared with experimental examinations
Surface Acoustic Wave Vibration Sensor Electronic System
The paper presents surface acoustic wave vibration sensor electronic system. The system cooperates with surface acoustic wave delay line. The sensor has been designed for electronic warning systems. The sensor is a four-terminal network. In the system, there is a cascade connection of sensors by means of coaxial cable. Test signal and constant supply voltage are jointly sent between sensors. Separating the signals, their summation and amplification of test signal as well as matching the line to impedance 50 Ω are performed by surface acoustic wave vibration sensor electronic system. The electronic system devices and the making of them are discussed. System development of such a sensor is presented and its design is analysed. Experimental examination results of surface acoustic wave vibration sensor are presented. Parasitic effects occurring in vibration sensor electronic system operation connected with electromagnetic coupling and ground current coupling are discussed
SAW Delay Line for Vibration Sensors
The paper presents an analysis of surface acoustic wave delay line. The line consists of two simple interdigital transducers placed on a ST-cut quartz plate. Mid-band operation frequency of the line is 74 MHz. The line will be applied for surface acoustic wave vibration sensor. At the immovable end of the plate there are electric signal feeds to both transducers. This is the cause of increase in signal value going directly between the transducers and the cause of line losses. By means of equivalent electric model of interdigital transducer a loss analysis of the line has been made at 50 Ω load. The analysis allows to minimize line losses by matching the transducers to 50 Ω impedance. This has been practically achieved by a design of transducer geometry and configuration matching 50 Ω impedance, by means of inductance. An analysis of repeated operation characteristics of two interdigital transducers has been made. A signal going directly through capacitance between transducers and signals reflected from the edge of piezoelectric substrate have been presented. Results of theoretical analysis have been compared with experimental examinations