Spin Polarization of Polyalanine Molecules in 2D and Dimer-Row Assemblies Adsorbed on Magnetic Substrates: The Role of Coupling, Chirality, and Coordination.

Propagation of electrons along helical molecules adsorbed on surfaces comes along with a robust spin polarization effect called chirality induced spin selectivity CISS. However, experiments on the molecular scale that allow a true correlation of spin effects with the molecular structure are quite rare. Here we have studied the structure of self-assembled chiral molecules and the electronic transmission and spin polarization of the current through the system by means of ambient scanning tunneling microscopy and spectroscopy in heterostructures of various α-helix polyalanine-based molecules (PA) adsorbed on Al2O3/Pt/Au/Co/Au substrates with perpendicular magnetic anisotropy. We have found a phase separation of the molecules into well-ordered enantiopure 2D hexagonal phases and quasi-1D heterochiral-dimer structures, which allows for the analysis of the spin polarization with almost atomic precision of PA in different phases. The spin polarization reaches up to 75% for chemisorbed molecules arranged in a hexagonal phase. On the contrary, for weakly coupled PA molecules without cysteine anchoring groups in a quasi-1D phase, a spin polarization of around 50% was found. Our results show that both the intermolecular interaction as well as the coupling to the substrate are important and point out that collective effects within the molecules and at the interfaces are required to achieve a high chiral induced spin selectivity.

Cooperative Effect of Electron Spin Polarization in Chiral Molecules Studied with Non-Spin-Polarized Scanning Tunneling Microscopy.

Polyalanine molecules (PA) with an α-helix conformation have recently attracted a great deal of interest, as the propagation of electrons through the chiral backbone structure comes along with spin polarization of the transmitted electrons. By means of scanning tunneling microscopy and spectroscopy under ambient conditions, PA molecules adsorbed on surfaces of epitaxial magnetic Al2O3/Pt/Au/Co/Au nanostructures with perpendicular anisotropy were studied. Thereby, a correlation between the PA molecules ordering at the surface with the electron tunneling across this hybrid system as a function of the substrate magnetization orientation as well as the coverage density and helicity of the PA molecules was observed. The highest spin polarization values, P, were found for well-ordered self-assembled monolayers and with a defined chemical coupling of the molecules to the magnetic substrate surface, showing that the current-induced spin selectivity is a cooperative effect. Thereby, P deduced from the electron transmission along unoccupied molecular orbitals of the chiral molecules is larger as compared to values derived from the occupied molecular orbitals. Apparently, the larger orbital overlap results in a higher electron mobility, yielding a higher P value. By switching the magnetization direction of the Co layer, it was demonstrated that the non-spin-polarized STM can be used to study chiral molecules with a submolecular resolution, to detect properties of buried magnetic layers and to detect the spin polarization of the molecules from the change in the magnetoresistance of such hybrid structures.

Near-infrared emission from spatially indirect excitons in type II ZnTe/CdSe/(Zn,Mg)Te core/double-shell nanowires.

ZnTe/CdSe/(Zn, Mg)Te core/double-shell nanowires are grown by molecular beam epitaxy by employing the vapor-liquid-solid growth mechanism assisted with gold catalysts. A photoluminescence study of these structures reveals the presence of an optical emission in the near infrared. We assign this emission to the spatially indirect exciton recombination at the ZnTe/CdSe type II interface. This conclusion is confirmed by the observation of a significant blue-shift of the emission energy with an increasing excitation fluence induced by the electron-hole separation at the interface. Cathodoluminescence measurements reveal that the optical emission in the near infrared originates from nanowires and not from two-dimensional residual deposits between them. Moreover, it is demonstrated that the emission energy in the near infrared depends on the average CdSe shell thickness and the average Mg concentration within the (Zn, Mg)Te shell. The main mechanism responsible for these changes is associated with the strain induced by the (Zn, Mg)Te shell in the entire core/shell nanowire heterostructure.

Magnetic field induced mixing of light hole excitonic states in (Cd, Mn)Te/(Cd, Mg)Te core/shell nanowires.

A detailed magneto-photoluminescence study of individual (Cd, Mn)Te/(Cd, Mg)Te core/shell nanowires grown by molecular beam epitaxy is performed. First of all, an enhancement of the Zeeman splitting due to sp-d exchange interaction between band carriers and Mn-spins is evidenced in these nanostructures. Then, it is found that the value of this splitting depends strongly on the magnetic field direction with respect to the nanowire axis. The largest splitting is observed when the magnetic field is applied perpendicular and the smallest when it is applied parallel to the nanowire axis. This effect is explained in terms of magnetic field induced valence band mixing and evidences the light hole character of the excitonic emission. The values of the light and heavy hole splitting are determined for several individual nanowires based on the comparison of experimental results to theoretical calculations.

Ancient DNA in historical parchments - identifying a procedure for extraction and amplification of genetic material.

Historical parchments in the form of documents, manuscripts, books, or letters, make up a large portion of cultural heritage collections. Their priceless historical value is associated with not only their content, but also the information hidden in the DNA deposited on them. Analyses of ancient DNA (aDNA) retrieved from parchments can be used in various investigations, including, but not limited to, studying their authentication, tracing the development of the culture, diplomacy, and technology, as well as obtaining information on the usage and domestication of animals. This article proposes and verifies a procedure for aDNA recovery from historical parchments and its appropriate preparation for further analyses. This study involved experimental selection of an aDNA extraction method with the highest efficiency and quality of extracted genetic material, from among the multi-stage phenol-chloroform extraction methods, and the modern, column-based techniques that use selective DNA-binding membranes. Moreover, current techniques to amplify entire genetic material were questioned, and the possibility of using mitochondrial DNA for species identification was analyzed. The usefulness of the proposed procedure was successfully confirmed in identification tests of historical parchments dating back to the 13-16th century AD.

Evaluation of a modified sampling method for molecular analysis of air microflora.

A serious issue concerning the durability of economically important materials for humans related to cultural heritage is the process of biodeterioration. As a result of this phenomenon, priceless works of art, documents, and old prints have undergone a process of decomposition caused by microorganisms. Therefore, it is important to constantly monitor the presence and diversity of microorganisms in exposition rooms and storage areas of historical objects. In addition, the use of molecular biology tools for conservation studies will enable detailed research as well as reduce the time needed to perform the analyses compared with using conventional methods related to microbiology and conservation. The aim of this study was to adapt the sampling indoor air method for direct DNA extraction from microorganisms, including evaluating the extracted DNA quality and concentration. The obtained DNA was used to study the diversity of mold fungi in indoor air using polymerase chain reaction-denaturing gradient gel electrophoresis in specific archives and museum environments. The research was conducted in 2 storage rooms of the National Archives in Krakow and in 1 exposition room of the Archaeological Museum in Krakow (Poland).

An economical and combined method for rapid and efficient isolation of fungal DNA.

DNA isolation is a crucial step of conducting genetic studies in any organism. However, this process is quite difficult when studying fungi because of the need to damage the fungal cell walls of specific structures. In this study, we developed a method for the rapid and efficient isolation of fungal DNA based on simultaneous mechanical and enzymatic cell wall degradation. There are several typical modifications of the standard phenol-chloroform DNA extraction method. This method can be modified to degrade the fungal cell wall. The first step of the presented DNA extraction included manual homogenization in modified lysis buffer. Next, enzymatic digestion using 2 enzymes was conducted, including lyticase and proteinase K. To carefully select the most favorable conditions, we developed an economical, rapid, and reliable method for fungal DNA extraction that ensures both high efficiency and proper purity, which are essential for further analyses.

Giant spin splitting in optically active ZnMnTe/ZnMgTe core/shell nanowires.

An enhancement of the Zeeman splitting as a result of the incorporation of paramagnetic Mn ions in ZnMnTe/ZnMgTe core/shell nanowires is reported. The studied structures are grown by gold-catalyst assisted molecular beam epitaxy. The near band edge emission of these structures, conspicuously absent in the case of uncoated ZnMnTe nanowires, is activated by the presence of ZnMgTe coating. Giant Zeeman splitting of this emission is studied in ensembles of nanowires with various average Mn concentrations of the order of a few percent, as well as in individual nanowires. Thus, we show convincingly that a strong spin sp-d coupling is indeed present in these structures.

Zn(1-x)MnxTe diluted magnetic semiconductor nanowires grown by molecular beam epitaxy.

It is shown that the growth of II-VI diluted magnetic semiconductor nanowires is possible by the catalytically enhanced molecular beam epitaxy (MBE). Zn(1-x)MnxTe NWs with manganese content up to x=0.60 were produced by this method. X-ray diffraction, Raman spectroscopy, and temperature dependent photoluminescence measurements confirm the incorporation of Mn(2+) ions in the cation substitutional sites of the ZnTe matrix of the NWs.

Copper concentration in body tissues and fluids in normal subjects of southern Poland.

Data on the concentration of the elements in the human body are important, for example, to estimate the amounts required to maintain a good healthy state or find their connections with morbidity and mortality. In this paper, the concentration of copper (by flame atomic absorption spectrometry) in material obtained from autopsy cases of nonpoisoned people (n = 130), aged from 14 to 80 years, between 1990-2006, is presented. The following values were found (mean +/- SD in micrograms of copper per gram or per milliliter): brain 3.32 +/- 1.50 (n = 43), liver 3.47 +/- 1.51 (n = 79), kidney 2.15 +/- 0.90 (n = 76), stomach 1.10 +/- 0.76 (n = 65), intestines 1.54 +/- 1.19 (n = 25), lung 1.91 +/- 1.30 (n = 27), spleen 1.23 +/- 0.28 (n = 3), heart 3.26 +/- 0.59 (n = 5), bile 3.60 +/- 1.67 (n = 13), and blood 0.85 +/- 0.19 (n = 73).

Contribution to the data on copper concentration in blood and urine in patients with Wilson's disease and in normal subjects.

Determination of copper in human tissues and body fluids may be crucial in the diagnosis of Wilson's disease. In this study we evaluated urinary copper excretion and urine and blood concentration in 14 patients in whom Wilson's disease was confirmed (group A) and in 21 subjects in whom the disease was only suspected (group B). The following values (mean +/- SD) were found: 24-h urine (microg Cu/24 h), 152 +/- 135 (A) and 31.8 +/- 10.9 (B); urine (microg Cu/ml), 0.091 +/- 0.087 (A) and 0.028 +/- 0.011 (B); and blood (microg Cu/ml), 0.62 +/- 0.25 (A) and 0.72 +/- 0.09 (B). By comparison, urine copper concentration in the group of apparently healthy subjects was 0.035 +/- 0.010 (n = 50), and blood copper concentration in autopsy cases of nonpoisoned people was 0.85 +/- 0.19 (n = 73).

[Efficiency assessment of investment in workers' health--economic issues]. / Ekonomiczne problemy oceny efektywnosci inwestowania w zdrowie pracujacych.

The economic analysis of efficiency of investment in health care and health at large by means of cost-benefit or cost-effectiveness techniques is the subject of implementation work in a number of countries. Poland's integration with the countries of the European Union justifies the need to understand and to use economic analyses. Unfortunately, these activities encounter many methodological and executive barriers. The investments in workers' health are not only investments in health care and the improvement of working conditions, but also in compensations, including financial ones, resulting from adverse effects of factors influencing the health of working population. The financial reporting system that exists in Poland does not ensure the possibility of full presentation of the aggregated data on the financing of activities for workers' health and diminishing of the adverse effects of factors present in the work environment. The information on the outcome of the investments in workers' health come from different sources, which means that it applies to different groups subjected to the analysis. The problem lies not only in the assessment of profitability of health investments but also in the social problem of the division of the resultant costs and benefits among various branches of the national economy. Therefore, the analyses involving mutual relations between individual sectors that invest in workers' health and those that bear consequences is essential in the terms of economic analyses. The authors present the determinants of economic evaluation in regard to health of working population in Poland.

[Efficiency of artificial neural networks for prediction of regional lymph node metastasis]. / Skutecznosc sztucznych sieci neuronowych w przewidywaniu przerzutów do regionalnych wezlów chlonnych.

A retrospective study of 90 patients suffering from laryngeal carcinoma who were surgically treated in the Department of Otolaryngology, Collegium Medicum, Jagiellonian University, Cracow, Poland, has been performed. In 26 patients metastases in regional lymph nodes has been found. Various clinical, histopathological and kariometric factors have been subject to analysis. The artificial neural networks techniques have been used for prediction of presence of metastases in lymph nodes. The artificial neural networks exhibit an ability to generalize, i.e. they can learn from exemplary sets of data. Therefore the patients data have been divided at random into two sets forming a learning set (70 patients) and a test set (20 patients). A series of simulations have been carried out, using networks of various architectures and experimentally selected learning parameters, giving the prediction results between 71% and 96% of correct recognitions. The best prediction results have been achieved for the network of triple layer perceptron type including 6 neurons in the hidden layer. The evaluation of factors related to the presence of metastases in lymph nodes has been also carried out using logistic regression method for several groups of patients including various numbers of cases. The data sets of the remaining patients have been used for testing the reliability of that statistical method, giving between 56% and 64% of correct recognitions. Therefore the possibilities of prediction of metastases presence in lymph nodes are better for the artificial neural networks method (up to 96% of correct classifications) i.m. comparison to the logistic regression method (only up to 64% of correct classifications for the same data sets).

[Value of magnesium and calcium in serum and hair of children and adolescents with neurologic diseases]. / Zawartosc magnezu i wapnia w surowicy i wlosach dzieci i mlodziezy ze schorzeniami ukladu nerwowego.

A group of children with neurological diseases was examined, in which in 70-95% (according to age) of children the contents of magnesium in hair and in 39-44% in serum were lowered. The most frequent neurological signs in the relevant group of children were described. A case of a child with hypomagnesemia in whom had been falsely diagnosed and positive therapeutic effects epilepsy were obtained after supplementation with magnesium preparations (Asmag, Magne B6) were presented.

A chemical and physicochemical study of an Egyptian mummy 'Iset Iri Hetes' from the Ptolemaic period III-I B.C.

Chemical and physicochemical examinations of the fragments of an Egyptian mummy dated between the 3rd and 1st century B.C. were performed. The chemical examinations indicated the presence of resin in the skull and in the fragments of bandages wrapped around the mummy. An analysis of the infrared spectra of the fragments indicated a type of resin originating from the Copal group. Physicochemical investigations showed that main chemical elements such as Ca, Mg, Na, K, P and trace chemical elements such as Fe, Zn, Cu, and Pb occurred in bone fragments in proportions typical for people living today. In tooth fragments, values were similar to normal except for K, P, and Zn, which were lower, and Pb, which was absent. In the fingernails, most elements were found in much higher concentrations except for Cu and Pb, which were lower. The results of the study in terms of their implications on mummification are discussed.

Analytical findings in a fatal poisoning with silver compound.

A 69-year-old male radio technician drank an unknown amount of a liquid and died within 5 h at a hospital. Mainly silver, potassium, and calcium, among other substances, were found in the residue of the liquid from the empty bottle by means of the spectrographic method (30.7% silver and 25.5% potassium using atomic absorption spectometry [AAS] method). The toxicological analysis of the postmortem material for silver performed by the flame AAS method (stomach, 2.43 micrograms/g; intestines, 1.12 micrograms/g; liver, 6.29 micrograms/g; kidney, 4.85 micrograms/g; spleen, 30.1 micrograms/g; heart, 10.8 micrograms/g; lung, 14.8 micrograms/g; and brain, 0.61 microgram/g) confirmed fatal silver compound poisoning. The results were verified by the standard additions technique and recovery examination. However, no increase in the potassium concentrations was observed in the postmortem material. There have been no data in available literature on the distribution of silver in tissues in people after oral administration of silver salts.

[Intravenous injection of metallic mercury--case report]. / Dozylne wstrzykniecie rteci Metalicznej--opis przypadku.

A case of a 16 year old male who injected intravenously metallic mercury is presented. The patient was admitted to the hospital due to slightly elevated fever and hemoptysis. Both symptoms presented themselves 18 months following intravenous injection of metallic mercury. Radiological examination disclosed fine metallic interstitial shadowing in the lung parenchyma. Metallic shadows were also present in the subcutaneous region of the cubital fossa. CT scans and USG examination disclosed similar deposition of metal in the liver, kidneys, lymph nodes and heart. The mercury serum and urine levels exceeded the normal values by hundreds. Encountered diagnostic problems are presented, also prognosis basing on data from literature is discussed.