Kacper Nowak

Fourier transform in THz measurements of refractive index

A Fourier Transform is applied to the coherent detection signal in the THz photomixer arrangement. The method is used in measurements of a refractive index of plastic materials.

Limitations of the terahertz photomixer

In the paper, Fourier transform has been used for calculations of a refractive index of dielectric samples measured in the terahertz photomixer arrangement. We considered measurement limitations caused by a sampling frequency and a photomixer bandwidth.

Piroxicam derivatives THz classification

In this paper we report a new approach to linking the terahertz spectral shapes of drug candidates having a similar molecular structure to their chemical and physical parameters. We examined 27 newly-synthesized derivatives of a well-known nonsteroidal anti-inflammatory drug Piroxicam used for treatment of inflammatory arthritis and chemoprevention of colon cancer. The testing was carried out by means of terahertz pulsed spectroscopy (TPS). Using chemometric techniques we evaluated their spectral similarity in the terahertz range and attempted to link the position on the principal component analysis (PCA) score map to the similarity of molecular descriptors. A simplified spectral model preserved 75% and 85.1% of the variance in 2 and 3 dimensions respectively, compared to the input 1137. We have found that in 85% of the investigated samples a similarity of the physical and chemical parameters corresponds to a similarity in the terahertz spectra. The effects of data preprocessing on the generated maps are also discussed. The technique presented can support the choice of the most promising drug candidates for clinical trials in pharmacological research.

Selected polymers on CW and pulsed THz investigations

The paper gives the results of refractive indexes for three plastic materials: polyethylene, polymethyl methacrylate and polyvinyl chloride, which are measured and compared in two arrangements - a CW THz photomixer and a pulsed THz spectrometer.

Interference aspects of terahertz transmission

In this paper, interference aspects of terahertz transmission are considered. Possible interference effects in indoor THz communication are experimentally proved using a THz photomixer setup. The method of coherent homodyne detection is applied to explain the problem. Fourier Transform is used for precise analysis of the interference effects and calculations of the optical path changes. The paper explains the problem of multipath communications in the terahertz range.

Chemometric Evaluation of THz Spectral Similarity for the Selection of Early Drug Candidates

In this paper we discuss the link between the domain of physical parameters – molecular descriptors of a drug, and terahertz (THz) spectra. We measured the derivatives of the well-known anti-inflammatory drug Piroxicam using THz spectroscopy and employed Principal Component Analysis to build similarity maps in the molecular descriptor and spectral domains. We observed, that the spatial neighborhood on the molecular descriptors map is highly correlated with the spectral neighbourhood within a group of structurally-similar molecules. We built a Partial Least Squares (PLS) predictive model to quantify the relationship between the spectra and the melting point, which can guide the selection of early drug candidates.

Terahertz investigations on some bi-heterocyclic compounds

Terahertz spectral investigations on drug candidates with similar molecular structures to their chemical and physical parameters are described and newly-synthesized derivatives of some bi-heterocyclic compounds are examined. Using chemometric techniques we evaluate their spectral similarity in the THz range. Principal Component Analysis (PCA) is used to solve the problem.

The gyrotron source for the EPR spectroscopy

A dynamic development of the spectroscopic tech- niques at different wavelengths and the development of promising sources of the microwave radiation create many new opportunities for utilizing these techniques in this field. One of sources of the high frequency electromagnetic radiation is gyrotron. In this paper its main advantages, such as stability and an increased spectral resolution in application to the EPR spectroscopy is discussed.

The role of Ir4 cluster in enhancing the adsorption of CO2 on selected zeolites - GCMC simulations

We have investigated the adsorption of CO2 molecules inside the EMT, SAO, SBS, SBT and IWS zeolites with respect to the influence of the Ir4 clusters on the adsorption capabilities of these materials. We have determined that the capabilities of CO2 adsorption depend on the combined effect of the framework topology and the position of the Ir4 cluster. Adsorption intensifies despite the fact that a fraction of the pore volume is occupied by the Ir4 cluster, and thus, the adsorption is more intense than that on empty zeolite. The pore topology however is also playing a crucial role in the effect, as in certain cases it allows the CO2 molecules to order in such a way they fill the most pore space.