Dynamics of nanoscale polarization fluctuations in a uniaxial relaxor.

We have studied neutron diffuse scattering in a Sr(0.61)Ba(0.39)Nb(2)O(6) single crystal by neutron backscattering at sub-µeV energy resolution. We can identify two response components with transverse polarization: an elastic (resolution limited) central peak, which monotonically increases with decreasing temperature, and a quasielastic central peak, having a maximum intensity around the ferroelectric phase transition close to 350 K. In contrast to previous neutron experiments on this and other relaxor materials, we were able to observe a temperature dependence of the characteristic frequency of these fluctuations, obeying the same Vogel-Fulcher law as the dynamic part of the dielectric permittivity of this material. In this way our findings provide a first direct link between the Vogel-Fulcher-type frequency dependence of dielectric permittivity and dynamic nanoscale lattice modulations with a transverse correlation length of about 5-10 unit cells.

Broad-band conductivity and dielectric spectroscopy of composites of multiwalled carbon nanotubes and poly(ethylene terephthalate) around their low percolation threshold.

Composites of multiwalled carbon nanotubes with poly(ethylene terephthalate) (PET-MWCNT) with up to 3 vol% MWCNTs were prepared and characterized by broad-band AC conductivity and dielectric spectroscopy up to the infrared range using several techniques. A very low electrical percolation threshold of 0.07 vol% MWCNTs was revealed from the low-frequency conductivity plateau as well as from DC conductivity, whose values show the same critical power dependence on MWCNT concentration with the exponent t = 4.3. Above the plateau, the AC conductivity increases with frequency up to the THz range, where it becomes overlapped with the absorption of vibrational modes. The temperature dependence down to ~5 K has shown semiconductor behaviour with a concentration-independent but weakly temperature-dependent small activation energy of ~3 meV. The behaviour is compatible with the previously suggested fluctuation-induced tunnelling conductivity model through a thin (~1 nm) polymer contact layer among the adjacent MWCNTs within percolated clusters. At higher frequencies, deviations from the simple universal conductivity behaviour are observed, indicating some distribution of energy barriers for an electron hopping mechanism.

Dielectric, magnetic and structural properties of novel multiferroic Eu(0.5)Ba(0.5)TiO(3) ceramics.

Dielectric properties of Eu(0.5)Ba(0.5)TiO(3) ceramics were investigated between 10 and 300 K in the frequency range of 1 MHz-100 THz. Permittivity exhibits a strong peak near the ferroelectric phase transition at 215 K. This is mainly due to softening of the lowest frequency polar phonon revealed in THz and infrared spectra. Dielectric relaxation was observed also below the ferroelectric soft mode frequency in the whole investigated temperature region, but it is probably caused by some defects such as Eu(3 + ) cations or oxygen vacancies. This implies that the ferroelectric phase transition has predominantly a displacive character. Raman scattering spectra revealed a lowering of crystal symmetry in the ferroelectric phase and XRD analysis indicated orthorhombic A2mm symmetry below 215 K. The magnetic measurements performed at various frequencies in the field cooled and field heating regime after cooling in zero magnetic fields excluded spin glass behavior and proved an antiferromagnetic order below 1.9 K in Eu(0.5)Ba(0.5)TiO(3).

Fast polarization mechanisms in the uniaxial tungsten-bronze relaxor strontium barium niobate SBN-81.

The high-frequency dielectric response of the uniaxial strontium barium niobate crystals with 81% of Sr has been studied from 1 kHz to 30 THz along the polar c axis by means of several techniques (far infrared, time domain terahertz, high-frequency and low-frequency dielectric spectroscopies) in a wide temperature interval 20-600 K. Relaxor properties were observed in the complex dielectric response and four main excitations were ascertained below the phonon frequencies. These fast polarization mechanisms take place at THz, GHz and MHz ranges and show different temperature evolution. The central mode excitation in the THz range, related to anharmonic dynamics of cations, slightly softens from high temperatures and then hardens below T ~ 400 K. Below the phase transition (at T ~ 330 K) an additional microwave excitation appears near 10 GHz related to micro domain wall oscillations. The strongest relaxation appears in the GHz range and slows down on cooling according to the Arrhenius law. Finally, another relaxation, present in the MHz range at high temperatures, also slows down on cooling at least to the kHz range. These two relaxations are due to polar fluctuations and nanodomains dynamics. Altogether, the four excitations explain the dielectric permittivity maximum in the kHz range.

Spectroscopic studies of the ferroelectric and magnetic phase transitions in multiferroic Sr1-xBaxMnO3.

Dielectric response of perovskite Sr1-xBaxMnO3 (x = 0.43 and 0.45) ceramics was investigated using microwave, THz and infrared spectroscopic techniques in order to study the ferroelectric and antiferromagnetic phase transitions with critical temperatures TC ≈ 350 K and TN ≈ 200 K, respectively. The two lowest-frequency polar phonons are overdamped above TN and they exhibit pronounced softening on heating towards TC. Nevertheless, permittivity ε' in the THz range shows only a small anomaly at TC because the phonon contribution to ε' is rather small. The phonons are coupled with a central mode which provides the main contribution to the dielectric anomaly at TC. Thus, the ferroelectric phase transition has characteristics of a crossover from displacive to order-disorder type. At the same time, the intrinsic THz central peak is partially screened by conductivity and related Maxwell-Wagner relaxation, which dominates the microwave and lower-frequency spectra. Below TN, the ferroelectric distortion markedly decreases, which has an influence on the frequencies of both the central and soft modes. Therefore, ε' in the THz range increases at TN on cooling. In spite of the strong spin-phonon coupling near TN, surprisingly no magnetodielectric effect was observed in the THz spectra upon applying magnetic field of up to 7 T, which is in contradiction with the theoretically expected huge magnetoelectric coupling. We explain this fact as due to the insensitivity of TN to magnetic field.

Soft and central mode behaviour in PbMg(1/3)Nb(2/3)O(3) relaxor ferroelectric.

The relaxor ferroelectric PbMg(1/3)Nb(2/3)O(3) (PMN) is investigated by means of dielectric and Fourier transform far infrared transmission spectroscopy in the frequency range from 10 kHz to 15 THz at temperatures between 20 and 900 K using mostly thin films on infrared transparent sapphire substrates. While the thin film relaxors display reduced dielectric permittivity at low frequencies, their high frequency lattice response is shown to be the same as for single-crystal/ceramic specimens. In contrast to the results of inelastic neutron scattering, the optic soft mode is found to be underdamped at all temperatures. On heating, the TO1 soft phonon follows the Cochran law with an extrapolated critical temperature of 670 K near to the Burns temperature. Above 450 K the soft mode frequency levels off near 50 cm(-1) and above the Burns temperature it slightly hardens. Central-mode-type dispersion assigned to the dynamics of polar nanoclusters appears below the Burns temperature at frequencies near to but below the soft mode and slows down and broadens dramatically on cooling, finally, below the freezing temperature of 200 K, giving rise to frequency independent losses from the microwave range down. A new explanation of the phonon 'waterfall' effect in inelastic neutron scattering spectra is proposed.

Trabecular bone pattern factor--a new parameter for simple quantification of bone microarchitecture.

The stability of trabecular bone depends not only on the amount of bone tissue, but also on the three-dimensional orientation and connectedness of trabeculae, which is summarized as trabecular microarchitecture. In previous studies we could demonstrate that in three-dimensional bone tissue the relation of trabecular plates to rods is reflected in the ratio of concave to convex surfaces of the bone pattern in two-dimensional bone sections. For the quantification of the connectedness of these bone patterns we developed a new histomorphometric parameter called Trabecular Bone Pattern factor (TBPf). The basic idea is that the connectedness of structures can be described by the relation of convex to concave surfaces. A lot of concave surfaces represent a well connected spongy lattice, whereas a lot of convex surfaces indicate a badly connected trabecular lattice in two-dimensional sections. By means of an automatic image analysis system we measure trabecular bone area (A1) and perimeter (P1). A second measurement of these two parameters (now A2 and P2) is done after a simulated dilatation of trabeculae on the screen. This dilatation results in a characteristic change of bone area and perimeter depending on the relation of convex to concave surfaces. TBPf is defined as a quotient of the difference of the first and the second measurement: TBPf = (P1 - P2)/(A1 - A2). First measurements of TBPf in 192 iliac crest bone biopsies of autopsy cases show that there is not only age-related loss of bone volume, but also a decrease of trabecular connectedness. By means of TBPf we can demonstrate a significant difference in the age-related loss of trabecular connectivity between male and female individuals.

The influence of short-term treatment with simvastatin on the inflammatory profile of patients with hypercholesterolaemia.

BACKGROUND: Treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors can reduce cardiovascular mortality of patients with atherosclerosis. This effect is probably due not only to a decrease in concentration of cholesterol, but also to non-lipid-involving mechanisms elicited by the action of statin drugs. OBJECTIVE: To investigate the influence of short-term therapy with simvastatin on markers of inflammation and oxidation processes in patients with hypercholesterolaemia. DESIGN: We administered 20mg simvastatin daily for 12 weeks to 19 patients with hypercholesterolaemia (250-400 mg/dl). Peripheral blood samples for evaluation of plasma concentrations of thiobarbituric acid reactive substances (malonaldehyde), stable metabolites of nitric oxide (NOx) and interleukin 6 (11-6) were taken before and after the therapy. RESULTS: Plasma levels of malonaldehyde decreased significantly (from 4.533+/-0.428 versus 3.690+/-0.310 micromol/l, P = 0.04) during the study period. Similarly, there was a significant decrease in the plasma concentrations of NOx (from 33.477+/-4.352 micromol/l versus 25.919+/-2.561 micromol/l, P = 0.02). There were significant positive correlations between concentrations of total cholesterol and NOx in plasma (r = 0.4397, P = 0.008) and of low-density lipoprotein and NOx (r = 0.3987, P = 0.02). The plasma level of interleukin 6 remained unchanged by the intervention (1.837+/-0.200 versus 1.820+/-0.169 pg/ml, P = 0.54). CONCLUSIONS: Short-term therapy with simvastatin decreases the plasma concentrations of markers of peroxidation of lipids and of stable metabolites of nitric oxide in hypercholesterolaemic patients, but leaves levels of interleukin 6 unaffected.

[Cost of the peritoneovenous shunt in patients with cirrhosis]. / Coût de la dérivation péritonéo-veineuse chez le cirrhotique.

The cost of peritoneovenous shunting was evaluated in 15 cirrhotic patients with intractable ascites. With the assessment presently used in French Public Hospitals which is based on a contractual reimbursement by the Social Security per day of hospitalization, the cost of peritoneovenous shunting was F 37,227.40. Using the more refined method of cost analysis, the cost of the operative procedure was F 9,564 and that of postoperative hospitalization was F 8,067. Total expenses calculated by the cost analysis method (F 17,631) were much less that the reimbursement paid by Social Security. This study allowed to determine the actual cost of Surgical treatment of ascites, where expenses were greatest, and how to reduce them. Results of this report should be used when comparing cost and efficacy of medical and surgical treatments.

[Bone structure changes in hip joint endoprosthesis implantation over the course of many years. A quantitative study]. / Knochenstrukturveränderungen nach mehrjähriger Hüftgelenksendoprothesen-Implantation. Eine quantitative Studie.

The stability of implanted artificial joints is limited. One main factor for this is the change of the bone tissue near the implant. Therefore we studied femura with stem endoprostheses derived from autopsy. All specimens were cut in horizontal and longitudinal sections. X-rays were made of all sections. Then the specimens were embedded undecalcified and ground to 10 microns. The wellknown phenomenons at the bone cement border were found too. Direct bone cement contact is about 5%. The 4 studied femura show a higher porosity of cortical bone as controls. The loss of cortical bone is up to 40% after 55 months. There is a correlation between new load situation and the localisation of bone loss.

[Christiaan Neethling Barnard--pioneer in human heart transplantation (on the 30th anniversary of the first heart transplantation]. / Christiaan Neethling Barnard--pionier transplantacji serca u czlowieka. (W 30 rocznice pierwszego w swiecie przeszczepu serca).

Christian Neethling Bernard--a South African cardiac surgeon--until 1983 a cardiothoracic surgeon at Groote Schuur Hospital, Cape Town; 1968-1983, Head of Cardiac Research and Surgery, University of Cape Town; developed new design artificial valves. He gained experience in heart transplant techniques in USA in Minneapolis (prof. C. Walton Lilehei), Richmond (Richard Lower) and Palo Alto (Norman E. Shumway). On December 3, 1967 in Cape Town he carried out first in the world transplant operation, which started the era of transplantology.

[Outstanding contribution of prof. Henryk M. Wisniewski (1931-1999) to the world neuropathology in 20th century]. / Wklad profesora dr. hab. Henryka M. Wisniewskiego (1931-1999) do swiatowej neurologii XX wieku.

Born in Poland in 1931, Henryk Miroslaw Wisniewski, obtained MD at the Medical School in Gdansk (1955), where he continued his neuropathological research awarded with Ph. D. in 1960. During 1961-1962 a worked as a Visiting Scientist at NIH (Institute of Neurology and Communicative Diseases and Stroke). In Medical School in Warsaw he was promoted to Docent degree (an associate professor). In 1966 he emigrated with his family to New York, where he was a Research Associate and Professor at Albert Einstein College of Medicine (1966-1975) Subsequently he became a Director of the State Institute for Basic Research in Developmental Disabilities Staten Island. In New York he remained till his early death at the age of 68. Prof. Wisniewski advanced pathological research concerning the development of dementia, including Alzheimer disease. His investigations proved that presentile dementia (Alzheimer disease) is almost identical with senile dementia. That is why he is called the pioneer of modern Alzheimers research. The comments about his scientific contribution were generously published in scientific journals and daily press. The New York Times cited Dr Mony de Leon Prof. of Psychiatry statement reflecting so well Prof. Wisniewski's achievements "He taught us what the lesions for Alzheimers looked like, what they were made of and how they worked".

[Henryk Jordan (1842-1907)--a dedicated Krakow physician, health promotor and welfare worker]. / Henryk Jordan (1842-1907)--zasluzony krakowski lekarz, promotor zdrowia i spolecznik.

The article presents Dr Jordan's life and professional career. His pioneering has been realized not only in Poland but in other European countries as well.

[Andrew Victor Schally: neuroendocrinologist of Polish origin]. / Andrew Victor Schally--zasluzony neuroendokrynolog Polskiego pochodzenia.

American scientist of Polish origin, won the Nobel Prize in the field of physiology and medicine. In this way he became one of three Polish Nobel Prize winners in the scientific field (among M. Sklodowska-Curie and Tadeusz Reichstein). On the 20th anniversary of this historic moment I describe his life, scientific activity and achievements.

[The application of lead in pharmacotherapy in time past and today]. / Wykorzystanie olowiu w farmakoterapii dawniej i dzis.

The review of literature shows that lead and its compounds accompany man from the beginning of mankind to present days. In the evolution of the therapeutic use of lead we can discern the periods of a fascination for its compounds, e.g. the antique, especially in Rome, and the galenic period up to the XVIII century. The development of chemistry, toxicology and pharmacology at the breach of XVIII and XIX century led to a limitation of lead use in the therapy. It must be emphasized that it never came to a resignation. It remains still an element of the traditional pharmacotherapy in many cultures, e.g. of Hindus, Westafricans and Mexicans.

[The state of hygiene and health care in Wilno at the end of the XIXth and at the beginning of the XXth century as described in the letters of doctor Wladyslaw Zahorski]. / Stan Higieny I lecznictwa w Wilnie na przelomie XIX I XX wieku w swietle listow doktora Wladyslawa Zahorskiego.

The letters of dr Wladyslaw Zahorski from Wilno published in "Nowiny Lekarskie" in the years 1899-1914 are a source of information on the condition of health and the level of health care of the Wilno population at the end of the XIXth and at the beginning of the XXth century. The sanitary condition of the city was very bad. Infectious diseases killed people in the thousands. Many superstitions and prejudices were being spread especially during an epidemic. Wilno did not have well equipped and organized hospitals. Apart from state hospitals, there were private small hospitals which had better conditions for treating people. Poor people were given some medical aid free. A fight against social ignorance, infectious diseases and to improve sanitary condition of the city was conducted by Wilno Medical Society.

An x-ray scattering study of Sn2P2S6: absence of incommensurate phase up to 1 GPa.

The ferroelectric phase transition in a semiconductor Sn(2)P(2)S(6) single crystal has been studied by means of high-resolution synchrotron x-ray diffraction in the pressure-temperature range where an incommensurate modulated phase has been anticipated for many years. In contrast with the predictions, the present measurements reveal only a direct ferroelectric-paraelectric phase transition close to T = 100 K, p = 1.1 GPa. In the vicinity of this phase transition, a characteristic critical diffuse scattering was observed, but no satellite peaks could be resolved there. It is concluded that the earlier hypothesis about the presence of an incommensurate phase and associated Lifshitz point in the temperature-pressure phase diagram of Sn(2)P(2)S(6) is incorrect.

The temperature dependence of the phononic band gap of NaI.

The position and size of the energy gap in the phonon density of states of NaI single crystal have been investigated by inelastic neutron scattering in a wide range of temperatures from 10 to 700 K. The results reveal a pronounced temperature effect which effectively leads to closure of the phonon gap at temperatures in the range of 700-800 K. The results are discussed in the context of studies of possible intrinsic localized modes in the phonon gap of alkali halides.

Bulk dielectric and magnetic properties of PFW-PZT ceramics: absence of magnetically switched-off polarization.

We investigated ceramics samples of solid solutions of [PbFe(2/3)W(1/3)O(3)](x)-[PbZr(0.53)Ti(0.47)O(3)](1 - x) (PFW(x)-PZT(1 - x), x = 0.2 and 0.3) by means of broad-band dielectric spectroscopy, differential scanning calorimetry and SQUID magnetometry. We did not confirm the observations of Kumar et al (2009 J. Phys.: Condens. Matter 21 382204), who reported on reversible suppression of ferroelectric polarization in polycrystalline PFW(x)-PZT(1 - x) thin films for magnetic fields above 0.5 T. We did not observe any change of ferroelectric polarization with external magnetic fields up to 3.2 T. Pirc et al (2009 Phys. Rev. B 79 214114) developed a theory explaining the reported large magnetoelectric effect in PFW(x)-PZT(1 - x), taking into account relaxor magnetic and relaxor ferroelectric properties of the system. Our data revealed classical ferroelectric properties below 525 K and 485 K in samples with x = 0.2 and 0.3, respectively. Moreover, paramagnetic behavior was observed down to 4.5 K instead of previously reported relaxor magnetic behavior. It seems that the reported switching-off of ferroelectric polarization in PFW(x)-PZT(1 - x) thin films is not an intrinsic property, but probably an effect of electrodes, interlayers, grain boundaries or second phases presented in polycrystalline thin films.