Marek Portalski

Evaluation of Five Phase Digitally Controlled Rotating Field Plasma Source for Photochemical Mercury Vapor Generation Optical Emission Spectrometry

A new sensitive method for total mercury determination in reference materials using a 5-phase digitally controlled rotating field plasma source (RFP) for optical emission spectrometry (OES) was developed. A novel synergic effect of ultrasonic nebulization (USN) and ultraviolet-visible light (UV-Vis) irradiation when used in combination was exploited for efficient Hg vapor generation. UV- and Vis-based irradiation systems were studied. It was found that the most advantageous design was an ultrasonic nebulizer fitted with a 6 W mercury lamp supplying a microliter sample to a quartz oscillator, converting liquid into aerosol at the entrance of the UV spray chamber. Optimal conditions involved using a 20% v/v solution of acetic acid as the generation medium. The mercury cold vapor, favorably generated from Hg(2+) solutions by UV irradiation, was rapidly transported into a plasma source with rotating field generated within the five electrodes and detected by digitally controlled rotating field plasma optical emission spectrometry (RFP-OES). Under optimal conditions, the experimental concentration detection limit for the determination, calculated as the concentration giving a signal equal to three times the standard deviation of the blank (LOD, 3σblank criterion, peak height), was 4.1 ng mL(-1). The relative standard deviation for samples was equal to or better than 5% for liquid analysis and microsampling capability. The methodology was validated through determination of mercury in three certified reference materials (corresponding to biological and environmental samples) (NRCC DOLT-2, NRCC PACS-1, NIST 2710) using the external aqueous standard calibration techniques in acetic acid media, with satisfactory recoveries. Mercury serves as an example element to validate the capability of this approach. This is a simple, reagent-saving, cost-effective and green analytical method for mercury determination.

The method of the measurement of the time between centre of chosen sounds

In this paper the method and the program to measurement of time distances between middle points of speaking or playing sounds was presented. The proposed algorithm can be used to the score of the human state for persons with dysfunction of the central nervous system. The differences between results obtained for healthy persons an impaired persons was shown.

Chosen Techniques for Processing of Pseudowhisper of the Laryngectomized

In this paper we present novel signal processing techniques for improvement of intelligibility of the so-called pseudowhisper, which is a kind of the residual speech, typical for the rest speaking abilities of a major part of the laryngectomized patients, i.e., of those, who went through the larynx (vocal cords) removal surgery. First of all we show how it is possible to suppress annoying vocal artifacts and other unusual disturbances, which are present in a typical pseudowhisper, such as tongue clicks, plosive sounds (consonants) and the tracheal outlet breath sounds, which typically occur in a pseudowhisper of the laryngectomized. Furthermore, this paper deals with an additional and very effective pseudowhisper postprocessing technique consisting in inserting vowels and other related voiced speech segments into the previously cleaned and denoised pseudowhisper (by means of the presented techniques) in order to make it drastically more comprehensible. Illustrative results of the intelligibility tests carried out by the authors before and after applying the suggested signal processing techniques are presented.