X-ray absorption near edge structure and Mössbauer spectroscopy in study of iron valence states in tissues

X-ray absorption near edge structure Fe K-edge spectra and $\text{}^{57}$Fe Mössbauer spectra of selected standard compounds were recorded at room temperature. Valence and spin states of Fe in these samples known from Mössbauer spectroscopy were correlated with the shapes of X-ray absorption near edge structure spectra in search of possible application of X-ray absorption near edge structure spectroscopy as analytical tool determining local electronic states of iron in tissues. As an example, the X-ray absorption near edge structure spectra of healthy and cancerous tissues of prostate are shown, suggesting Fe$\text{}^{3+}$ in cancerous tissues

Applications of the Cracow X-ray microprobe in tomography

A nuclear microprobe at the IFJ PAN in Cracow has found numerous applications in different fields of research, mostly in biophysics, medical sciences, geology, and material research. In order to extend the research possibilities, a new X-ray microprobe was constructed. This new microprobe consists of three experimental lines dedicated to: (i) X-ray irradiation of biological specimens, (ii) elemental analysis of samples by micro X-ray fluorescence or total reflection X-ray fluorescence methods and (iii) computer microtomography. In this paper the computer microtomography line was described. The line consists of an open type Hamamatsu L9191 X-ray tube with microfocusing to about 2 μm, a high resolution X-ray sensitive CCD camera, and a precise goniometer composed of six piezoelectric motors. Depending on the required X-ray energy, the Hamamatsu tube is used with Ti, Mo, Ag, or W targets. A small focus size and short focus-to-object distance enable to obtain images of samples with a magnification of more than 1000× and resolution of the order of 2 μm. The computer microtomography measurements are carried out using home developed codes combined with commercial software. Details of the microprobe construction and preliminary results of the computer microtomography experiments are presented

Stress drop-magnitude dependence of acoustic emissions during laboratory stick-slip

Earthquake source parameters such as seismic stress drop and corner frequency are observed to vary widely, leading to persistent discussion on potential scaling of stress drop and event size. Physical mechanisms that govern stress drop variations arc difficult to evaluate in nature and are more readily studied in controlled laboratory experiments. We perform two stick-slip experiments on fractured (rough) and cut (smooth) Westerly granite samples to explore fault roughness effects on acoustic emission (AE) source parameters. We separate large stick-slip events that generally saturate the seismic recording system from populations of smaller AE events which are sensitive to fault stresses prior to slip. AE event populations show many similarities to natural seismicity and may be interpreted as laboratory equivalent of natural microseismic events. We then compare the temporal evolution of mechanical data such as measured stress release during slip to temporal changes in stress drops derived from Alis using the spectral ratio technique. We report on two primary observations: (1) In contrast to most case studies for natural earthquakes, we observe a strong increase in seismic stress drop with AE size. (2) The scaling of stress drop with magnitude is governed by fault roughness, whereby the rough fault shows a more rapid increase of the stress drop magnitude relation with progressing large stick-slip events than the smooth fault. The overall range of AE sizes on the rough surface is influenced by both the average grain size and the width of the fault core. The magnitudes of the smallest AE events on smooth faults may also be governed by grain size. However, AEs significantly grow beyond peak roughness and the width of the fault core. Our laboratory tests highlight that source parameters vary substantially in the presence of fault zone heterogeneity (i.e. roughness and narrow grain size distribution), which may affect seismic energy partitioning and static stress drops of small and large AE events

EXAFS studies of prostate cancer cell lines

Sulphur plays a vital role in every human organism. It is known, that sulphur-bearing compounds, such as for example cysteine and glutathione, play critical roles in development and progression of many diseases. Any alteration in sulphur's biochemistry could become a precursor of serious pathological conditions. One of such condition is prostate cancer, the most frequently diagnosed malignancy in the western world and the second leading cause of cancer related death in men. The purpose of presented studies was to examine what changes occur in the nearest chemical environment of sulphur in prostate cancer cell lines in comparison to healthy cells. The Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy was used, followed by theoretical calculations. The results of preliminary analysis is presented

Seismic moment tensor and b value variations over successive seismic cycles in laboratory stick-slip experiments

The formation of fault damage due to slip under high normal stresses can rarely be monitored under in situ conditions. To advance our understanding of microfracture processes, we investigated stick-slip events on Westerly granite samples containing the following: (1) a planar saw cut fault and (2) a fault developed from a fresh fracture surface. We examined temporal changes of seismic moment tensors and b values of acoustic emission (AE) events. During experiment on the saw cut surface, small AEs exhibiting non-double-couple components were observed continuously and strong AEs displaying double-couple components were visible only when approaching the slip onsets. Sliding on naturally fractured surfaces showed, in addition to double-couple components, significant volumetric contributions, especially during the interslip periods and immediately after stick-slip events indicating substantial shear-enhanced compaction within a relatively broad damage zone. The obtained results shed light on how differences in fault structure control the kinematics of microseismicity during different periods of the seismic cycle

Chemical composition of atherosclerotic plaques of apoE/LDLR-double knockout mice by synchrotron radiation FTIR microspectroscopy

Atherosclerosis is a multietiological inflammatory disease of large and medium-sized arteries of increasing incidence in westernized countries. The aim of this study was to identify the biochemical changes during the progression of atherosclerosis by synchrotron radiation Fourier transform infrared microspectroscopy in atheromas of apoE/$LDLR^{-//-}$ mice fed egg-rich diet supplemented or not with angiotensin converting enzyme inhibitor perindopril. Synchrotron radiation Fourier transform infrared microspectroscopy technique was used to obtain information at high spatial resolution about the distribution of proteins (C-N, N-H, CO for amide I and amide II bands), lipids ($CH_2$, $CH_3$ bands) as well as mineral deposits (calcium carbonates and phosphates). Total contents of lipids and proteins were found to be significantly lower in animals treated with the diet and perindopril. An increase in saturation level of lipids was observed in animals fed with egg-rich diet when compared to the normal diet and perindopril treatment, which did not inhibit this effect. Moreover, a significant change in the secondary structure of proteins (ratio between absorption bands 1634 $cm^{-1}$/1656 $cm^{-1}$ attributed to β-type and α-type, respectively) was observed in both experimental groups in comparison with the control. Principal component analysis was used to analyse the recorded spectra. It has revealed that higher content of phosphates (wavenumber range 950-1020 $cm^{-1}$) was observed between egg-rich diet fed animals and the control group

Preliminary studies of sediments from the Dobczyce drinking water reservoir

The analysis of river and lake sediments indicates that the physical, chemical, biochemical and geochemical processes that influence the fate of toxic compounds and elements in sediments are numerous and complex (for example: sorption - desorption, oxidation - reduction, ion-exchange, biological activity). Due to the above-mentioned general statement, only a long term and complex research programme can lead to satisfactory answers to the questions relating to possible changes of water and environmental quality in the future. The aim of our study consisted in physical and chemical characterisation of sediments in in-depth profiles taken from the Dobczyce reservoir in southern Poland that is a main source of drinking water for the city of Kraków. Due to morphological reasons, 7 layers of sediment samples were distinguished from the ground level to about 90 cm below (total thickness of the sediments in the sampling site). Analysis of grain size distribution and application of x-ray diffraction method, enabled mineralogical description of sediments. The use of proton-induced x-ray emission (PIXE) and atomic absorption spectrometry (AAS) revealed elemental composition of the samples (Al, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn). Concentrations of natural 40K and artificial 137Cs radionuclides were determined by the use of gamma spectrometry. The following facts were established: 1) the oldest (deepest) and newest, recently deposited layers of sediments are similar in their physical and chemical properties. It means that the inflow of contaminants and biogenic compounds to the reservoir has changed little since it was constructed and filled with water; 2) the severe flood in 1997 changed significantly sediment composition and, in fact, led to purification of sediments in the Dobczyce reservoir

Preliminary investigations of elemental content, microporosity, and specific surface area of porous rocks using PIXE and X-ray microtomography techniques

Determination of physical properties of porous geological materials is of great importance for oil industry. The knowledge of rocks properties is usually obtained from porosity studies such as pore size distribution, specific surface area determination, and hydrodynamic permeability calculations. This study describes determination of elemental composition and measurements of the particular physical properties of geological samples (porous sandstone rocks) by means of the nuclear and X-ray microprobes at the Institute of Nuclear Physics, Polish Academy of Sciences in Kraków, Poland. The special emphasis has been put on the computed microtomography method. Measurements have been carried out in close cooperation with Department of Geophysics, FGGEP AGH in Kraków, Poland. Chemical composition of the Rotliegend sandstone rock samples (few millimeters diameter), extracted from a borehole at 2679.6 m, 2741.4 m and 2742.4 m depth have been investigated using the 2.2 MeV proton beam (proton induced X-ray emission technique). Next, measurements of the porosity and the specific surface area of the pore space have been carried out using the X-ray microtomography technique. Basing on microtomographic data obtained with the high spatial resolution, simulations of the fluid dynamic in the void space of porous media have been carried out. Lattice Boltzmann method in the 3DQ19 geometrical model has been used in order to predict the hydraulic permeability of the media. In order to avoid viscosity-permeability dependence the multiple-relaxation-time model with half-way bounce back boundary conditions has been used. Computing power-consuming processing has been performed with the use of modern grid infrastructure

Secondary Transition Predictors of Postschool Success: An Update to the Research Base

Research suggests youth with disabilities are less likely to experience positive outcomes compared to peers without disabilities. Identification of in-school predictors of postschool success can provide teachers (e.g., special education, general education, career technical education), administrators, district-level personnel, and vocational rehabilitation counselors with information to design, evaluate, and improve transition programs. The purpose of this systematic literature review was to examine secondary transition correlational literature to identify additional evidence to support existing predictors and identify new predictors of postschool success. Results provided additional evidence for 14 existing predictors and identified three new predictors. Limitations and implications for research, policy, and practice are discussed

Updating the Secondary Transition Research Base: Evidence- and Research-Based Practices in Functional Skills

Transition education should be grounded in quality research. To do so, educators need information on which practices are effective for teaching students with disabilities transition-related skills. The purpose of this systematic literature review was to identify evidence-based and research-based practices in secondary special education and transition for students with disabilities. This systematic review resulted in the identification of nine secondary transition evidence-based practices and 22 research-based practices across more than 45 different transition-related skills. The range of effects for each of the secondary transition evidence-based and research-based practices identified are also included. Limitations and implications for future research, policy, and practice are discussed