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Актуальність. На сьогодні вентральний цервікоспондилодез є найбільш поширеним методом хірургічної корекції більшості травматичних ушкоджень субаксіального відділу хребта. Незважаючи на широкий асортимент тілозамінних систем, у сучасній літературі відсутні дані про переваги застосування певного типу конструкцій при різних варіантах пошкодження остеолігаментозного апарата. Мета — рентгенологічна оцінка ефективності використання тілозамінностабілізуючих систем при різних варіантах травматичних ушкоджень шийного відділу хребта. Матеріали та методи. Проведено аналіз даних рентгенограм 70 пацієнтів, які перенесли вентральний субаксіальний цервікоспондилодез у зв’язку з травматичним пошкодженням шийного відділу хребта. Проведено дослідження ефективності відновлення сегментарного кіфозу оперованого сегмента і стабільності досягнутої корекції в післяопераційному періоді. Терміни спостереження: інтраопераційно, через 3–5 днів, 3, 6 і 12–18 місяців після оперативного втручання. Як система стабілізації використані комбінація «Mesh + вентральна пластина» і телескопічний тілозамінний імплант. Переломи класифіковані згідно з основними класами AOSpine subaxial cervical spine injury classification system. Результати. Інтраопераційні рентгенограми свідчать про більш дозовану корекцію сегментарного кіфозу оперованого сегмента при застосуванні тілозамінного імпланту. При цьому 87,5 % аналізованих випадків містяться в необхідному діапазоні значень. При застосуванні комбінації Mesh із вентральною пластиною цей показник становив 50 %. Аналіз динаміки втрати корекції свідчить про більшу стабільність досягнутого спондилодезу при застосуванні тілозамінного імпланту. На 3-тю — 5-ту добу післяопераційного періоду максимальне наростання сегментарного кіфозу зареєстроване при С-типі ушкодження і застосуванні комбінації Mesh із вентральною пластиною. Мінімальна деформація відзначена при використанні тілозамінного імпланту та при А-типі ушкодження. Аналогічна залежність спостерігається на всіх подальших термінах спостереження. Висновки. При виконанні вентрального субаксіального цервікоспондилодезу пошкодження типу А є найбільш стабільними, а пошкодження типу С проявляють максимальну схильність до втрати досягнутої інтраопераційної корекції. Застосування тілозамінного імпланту порівняно з комбінацією Mesh із вентральною пластиною забезпечує більше збереження сагітального контуру оперованого сегмента на всіх термінах спостереження.

Актуальність. Механічна компресія вмісту хребетного каналу, що виникає при травматичному пошкодженні хребта, має основоположне значення при визначенні тактики терапії і прогнозів регресу неврологічних розладів у постраждалих. Аналіз даних літератури демонструє відсутність критерію, який дозволяє характеризувати морфологічно гетерогенний субстрат, що викликає компресію спинного мозку. Мета: сформулювати визначення, розробити і виконати перевірку вірогідності рентгенограмметричного методу оцінки сагітального розміру різних за морфологічним типом вентрально-інтраканально розташованих травматичних субстратів. Матеріали та методи. Інформаційний пошук дозволив виявити існуючі індекси і методи вимірювання ступеня компресії хребетного каналу, а також клінічну значимість характеру і ступеня компресії спинного мозку травматичним субстратом. Для первинної перевірки вірогідності методу оцінювання вентрально розташованого травматичного субстрату був проведений ретроспективний аналіз даних нейровізуалізації 150 пацієнтів із травматичними змінами шийного відділу хребта. Були проаналізовані дані спондилограм, комп’ютерних та магнітно-резонансних томограм. Вимірювання проводились трьома незалежними експертами. Результати. Розроблений термін «компримуючий фактор», що становить собою збірне поняття і відображає загальну характеристику патологічних анатомічних субстратів, які виникають при ушкодженнях хребетного рухового сегмента, що призводять до деформації стінок хребетного каналу і, як наслідок, викликають здавлення структур хребетного каналу. Для кількісної характеристики виконувалось вимірювання сагітального розміру компримуючого фактора, що має абсолютну метричну величину і характеризує відносний ступінь зміщення субстрату в просвіт хребетного каналу. Отримані при статистичній обробці результати виявляють високу відтворюваність результатів вимірювань. Коефіцієнт конкордації становив 0,85 при р = 0,00025. Висновки. Наведену радіологічну ознаку доцільно використовувати для загальної характеристики клінічного випадку, а також при статистичній обробці даних із метою уніфікації уявлення про ступінь компресії вмісту хребетного каналу.

We present studies of the influence of the chemical composition changes on the type of magnetic order present in bulk nanocomposite Ge 1− x−y Pb x Cr y Te crystals with the average Pb-content close to x ≈ 0.20 and Cr-content, y , varying from y = 0.017 up to 0.043. Detailed magnetometric studies revealed the existence of two ordered magnetic states present in all our samples. All our crystals show a paramagnet to spin-glass-like state transition at temperatures from 135 K to 145 K, related to the presence of Cr 5 Te 8 clusters in the host lattice. The second transition type depends on the Cr-content, y . In the case of samples with y equal to 0.038 and 0.043 the ferromagnetic phase is observed with T C slightly below 70 K, while in samples with lower chromium concentration the presence of spin-glass-like state slightly below 50 K is observed. The presence of clusters in our samples has significant impact on the carrier transport and magnetotransport in our samples. The presence of critical scattering on the magnetic impurities is observed in resistivity and magnetoresistance data. Nearly-linear magnetoresistance is also observed in our samples indicating a presence of strong scattering on the grain boundaries in our samples.

We present studies of magnetotransport properties of Ge 1− x − y Pb x Mn y Te bulk crystals with chemical composition changing from 0.180 x y T SG around 90 K. The presence of strong anomalous Hall effect (AHE) with hysteresis is observed at T T SG . The data analysis allowed calculation of a correction to the Hall constant R H for T T SG and the AHE constant, R S . R S is around 10 −6 m 3 /C. R S and R H do not change strongly with temperature. The scaling law analysis has proved that the AHE in this system is due to the extrinsic mechanisms dominated by the skew scattering with relatively small contribution of the side jump process. Strong localization occurs in our system at T T SG and causes a presence of a minimum in the resistivity vs. temperature dependence. The magnetoresistance of our samples shows complex behavior at T T SG . The negative magnetoresistance is observed at T T nearly linear positive magnetoresistance is observed at temperatures from 20 K up to T ≈ T SG , where it reaches maximum. Positive linear magnetoresistance is related to the granular nature of our samples while the maximum near T SG is related to the giant spin-splitting of the valence band.

We present the studies of structural, electrical, and magnetic properties of bulk Sn 1 − x − y Cr x Eu y Te crystals with different chemical compositions varying in the range of 0.004 ≤ x ≤ 0.089 and 0.007 ≤ y ≤ 0.020. The structural characterization of our samples indicated the clustering of the Cr-ions into Cr–Te related clusters. Eu ions do not form clusters and are randomly distributed in the SnTe lattice. The magnetotransport studies show the presence of positive linear magnetoresistance with maximum amplitude of about 80% for all our samples. Positive magnetoresistance is a geometrical effect related to the presence of clusters in the SnTe lattice. The cluster-glass-like state at the temperature of about 130 K is observed for x ≤ 0.025. The cluster-glass-like state is due to the presence of Cr-rich clusters in the SnTe lattice. The ferromagnetic behavior with the Curie temperature of about 275 K is observed for the samples with x > 0.077 indicating the presence of Cr 5 Te 8 clusters in the host material. Eu ions presence in our samples shows paramagnetic behavior.

We present the studies of structural, magnetotransport, and magnetic properties of Ge1−x Eu x Te bulk crystals with the chemical composition, x, changing from 0.008 to 0.025. For the samples with x > 0.015 the sample synthesis leads to formation of Ge1−x Eu x Te spinodal decompositions with a broad range of chemical contents. The presence of Ge1−x Eu x Te spinodal decompositions is responsible for the antiferromagnetic order in our samples with x > 0.015. For the samples with x

We present studies of magnetic properties of Ge 1− x − y Pb x Mn y Te bulk crystals with chemical composition varying in the range of 0.180 x y J pd , having values from 0.47 eV to 0.80 eV gives spin-glass transition temperature, T SG , values close to the experimental values for the Ge-rich phase. The magnetic order observed for the Pb-rich phase is also due to the carrier mediated magnetic interaction. The experimental transition temperatures are fitted with J pd value ranging from 0.22 eV to 0.28 eV.

L. Kilanski, M. Szyma«ski, B. Brodowska, M. Gorska, R. Szymczak, A. Podgorni, A. Avdonin, A. Reszka, B.J. Kowalski, V. Domukhovski , M. Arciszewska, W. Dobrowolski, V.E. Slynko and E.I. Slynko Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warszawa, Poland Faculty of Materials Engineering, Warsaw University of Technology, Woaoska 141, 02-507 Warszawa, Poland Institute of Materials Science Problems, Ukrainian Academy of Sciences, 5 Wilde Str., 274001 Chernovtsy, Ukraine

We present the studies of Sn/1-x/Cr/x/Te semimagnetic semiconductors with chemical composition x ranging from 0.004 to 0.012. The structural characterization indicates that even at low average Cr-content x < ?0.012, the aggregation into micrometer size clusters appears in our samples. The magnetic properties are affected by the presence of clusters. In all our samples we observe the transition into the ordered state at temperatures between 130 and 140 K. The analysis of both static and dynamic magnetic susceptibility data indicates that the spin-glass-like state is observed in our samples. The addition of Cr to the alloy seems to shift the spin-glass-like transition from 130 K for x = 0.004 to 140 K for x = 0.012., 4 pages, 4 figures

Sputtering of PbTe crystals by Ar+ plasma with ion energies 50–550 eV is investigated. A dependence of sputter yields of the Te and Pb on the sputtering ion energy and sputtering time is measured. New phenomena: aperiodical oscillations of Pb and Te sputtering; a huge preference of Te sputtering reaching more than two orders of magnitude at the beginning of sputtering process; and a significant excess of Te integrated sputter yield over that of Pb for prolonged sputtering by low energy plasma at 50–160 eV, are observed. It is substantiated that these phenomena can be caused by the peculiarities of the charge states of the interstitial Pb and Te in PbTe crystal matrix and the processes of re-deposition of sputtered atoms on the sputtered surface.

We present the study of magnetic and transport properties of Pb(1-x-y-z)Mn(x)Sn(y)Eu(z)Te. AC magnetic susceptibility measurements as well as transport characterization were performed. The obtained results indicate that the presence of two types of magnetic ions influences magnetic properties of investigated IV-VI semimagnetic semiconductor. A qualitative analysis and possible mechanisms of the substantial dependence of the Curie temperature on the Eu content are presented. The most likely reason of the observed Curie temperature behaviour is a strong dependence of the location of a heavy mass Sigma band upon the alloy composition. The theoretical calculations in frame of simple models confirm this point.

The purpose of this study was to investigate the magnetotransport properties of the Ge(0.743)Pb(0.183)Mn(0.074)Te mixed crystal. The results of magnetization measurements indicated that the compound is a spin-glass-like diluted magnetic semiconductor with critical temperature TSG = 97.5 K. Nanoclusters in the sample are observed. Both, matrix and clusters are magnetically active. Resistivity as a function of temperature has a minimum at 30 K. Below the minimum a variable-range hopping is observed, while above the minimum a metallic-like behavior occurs. The crystal has high hole concentration, p = 6.6E20 cm-3, temperature-independent. Magnetoresistance amplitude changes from -0.78 to 1.18% with increase of temperature. In the magnetotransport measurements we observed the anomalous Hall effect (AHE) with hysteresis loops. Calculated AHE coefficient, RS = 2.0E6 m3/C, is temperature independent. The analysis indicates the extrinsic skew scattering mechanism to be the main physical mechanism responsible for AHE in Ge(0.743)Pb(0.183)Mn(0.074)Te alloy., Comment: 4 pages, 3 figures

The study of transport and of magnetic properties of Pb1-xGexTe:Yb mixed crystals (0 = x = 0.04) is reported. It is shown that Yb forms a donor state resonant with the PbTe valence band. The donor state position may be tuned (shifted relative to the energy gap) by admixture of Ge. The properties of the Yb ion in the Pb1-xGexTe matrix makes the system unique from the point of view of magnetic properties. It is demonstrated that the change of the conductivity type from p to n induces transitions from the paramagnetic state to the diamagnetic one.

We present the experimental evidence for the presence of spinodal decomposition of the magnetic ions in the Ge/1-x-y/Cr/x/Eu/y/Te samples with chemical composition varying in the range of 0.015 < x < 0.057 and 0.003 < y < 0.042. The ferromagnetic transition at temperatures 50 < T < 57 K was observed, independent of the chemical composition. The long-range carrier mediated itinerant magnetic interactions seem to be responsible for the observed ferromagnetic order. The magnetic irreversibility with coercive field H/C/ = 5?63 mT and the saturation magnetization M/S/ 2?6 emu/g are found to strongly depend on the chemical composition of the alloy., 4 pages, 4 figures

We present the studies of magnetic properties of Ge/1-x/Cr/x/Te diluted magnetic semiconductor with changeable chemical composition 0.016 \leq x \leq 0.061. A spin-glass state (at T \leq 35 K) for x = 0.016 and 0.025 and a ferromagnetic phase (at T < 60 K) for x \geq 0.030 are observed. The long range carrier-mediated magnetic interactions are found to be responsible for the observed magnetic ordering for x < 0.045, while for x \geq 0.045 the spinodal decomposition of Cr ions leads to a maximum and decrease of the Curie temperature, TC, with increasing x. The calculations based on spin waves model are able to reproduce the observed magnetic properties at a homogeneous limit of Cr alloying, e.g. x < 0.04, and prove that carrier mediated Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction is responsible for the observed magnetic states. The value of the Cr-hole exchange integral, Jpd, estimated via fitting of the experimental results with the theoretical model, is in the limits 0.77...0.88 eV., 8 pages, 7 figures

Magnetotransport properties of spin-glass-like Ge/1-x-y/Sn/x/Mn/y/Te mixed crystals with chemical composition changing in the range of 0.083 < x < 0.142 and 0.012 < y < 0.119 are presented. The observed negative magnetoresistance we attribute to two mechanisms i.e. weak localization occurring at low fields and spin disorder scattering giving contribution mainly at higher magnetic fields. A pronounced hysteretic anomalous Hall effect (AHE) was observed. The estimated AHE coefficient shows a small temperature dependence and is dependent on Mn-content, with changes in the range of 10E-7 < R_S < 10E-6 m^3/C. The scaling law analysis has proven that the AHE in this system is due to the extrinsic mechanisms, mainly due to the skew scattering accompanied with the side jump processes., 7 pages, 4 figures

We investigated the nature of the magnetic phase transition in ${\text{Ge}}_{1\ensuremath{-}x\ensuremath{-}y}{\text{Sn}}_{x}{\text{Mn}}_{y}\text{Te}$ mixed crystals with chemical composition changing in the range of $0.083\ensuremath{\le}x\ensuremath{\le}0.142$ and $0.012\ensuremath{\le}y\ensuremath{\le}0.119$. The dc magnetization measurements performed in magnetic fields up to 90 kOe and temperature range 2--200 K showed that the magnetic ordering at temperatures below $T=50\text{ }\text{K}$ exhibits features characteristic for both spin-glass and ferromagnetic phases. The modified Sherrington-Southern model was applied to explain the observed transition temperatures. The calculations showed that the spin-glass state is preferred in the range of the experimental carrier concentrations and Mn contents. The value of the Mn hole exchange integral was estimated to be ${J}_{pd}=0.45\ifmmode\pm\else\textpm\fi{}0.05\text{ }\text{eV}$. The experimental magnetization vs temperature curves were reproduced satisfactorily using the noninteracting spin-wave theory with the exchange constant ${J}_{pd}$ values consistent with those calculated using modified Sherrington-Southern model. The magnetization vs magnetic field curves showed nonsaturating behavior at magnetic fields $Bl90\text{ }\text{kOe}$ indicating the presence of strong magnetic frustration in the system. The experimental results were reproduced theoretically with good accuracy using the molecular-field-approximation-based model of a disordered ferromagnet with long-range Ruderman-Kittel-Kasuya-Yosida interaction.

In this work we present a comparison of the experimental results, which have been obtained in the resonant photoemission study of electronic structure of epitaxial layers and bulk crystals of GeTe doped with Mn and/or Eu. Narrow-gap IV–VI semiconductors are known to form solid solutions not only with magnetic ions with partially filled 3d shell (e.g. Mn, Fe), but also with the elements with partially filled 4f shell (e.g. Eu, Gd). Such diluted magnetic semiconductors (DMS) exhibit transport, optical and magnetic properties attracting large interest from the point of view of basic research as well as of applications in infrared radiation sources, detectors, thermoelectric generators and, recently, spintronic devices. The ferromagnetic ordering in IV-VI –based diluted magnetic semiconductors (DMS) is governed by the Ruderman–Kittel–Yoshida–Kasuya interaction mediated by free holes related to native defects. Ge

Magnetic and transport properties of Ge1−x−yMnxEuyTe crystals with chemical compositions 0.041 ≤ x ≤ 0.092 and 0.010 ≤ y ≤ 0.043 are studied. Ferromagnetic order is observed at 150

The galvanomagnetic properties in weak magnetic fields (4.2≤T≤300 K, B≤0.07 T) and the Shubnikov-de Haas effect (T = 4.2 K, B≤7 T) in the single crystal Pb1-x-ySnxVyTe (x = 0.05-0.20, y≤0.01) alloys at atmospheric pressure and under hydrostatic compression up to 15 kbar have been investigated. We found that the increase of the vanadium impurity content leads to the p-n-conversion, transition to the insulating phase and to the pinning of Fermi level by the deep impurity level, lying under the bottom of the conduction band. Under pressure a decrease of the activation energy of the vanadium level, the n-p-inversion of the conductivity type at low temperatures and an insulator-metal transition occur. The pressure and the temperature coefficients of vanadium deep level energy are determined and the diagram of the electronic structure rearrangement for Pb1-x-ySnxVyTe under pressure is proposed.

We investigate galvanomagnetic effects near the insulator-metal transition induced by pressure in Pb1−xGexTe (x=0.10, 0.13) alloys doped with chromium (4.2≤T≤300 K, B≤8 T). We observe nonlinearity in the magnetic field dependencies of Hall voltage and peaks of anomalous scattering in the temperature dependencies of resistivity. These are due to the conductivity via chromium impurity band and to the structural phase transition from the cubic NaCl phase to the rhombohedral GeTe phase. Magnetic field dependencies of the Hall coefficient RH(B) are calculated in the framework of two-band conduction model. The main parameters of charge carriers are determined. Pressure dependencies of the critical phase transition temperature are obtained.

The temperature and magnetic field dependencies of magnetization (T=5-340 K, B≤0.5 T) as well as electron paramagnetic resonance (EPR) (T=80-400 K) in Pb1−xCrxTe (x≤0.045) have been studied. It was shown that all samples are ferromagnetic with a clear hysteresis loop up to the room temperature and magnetic saturation moment rises with increasing of the chromium content. Using temperature dependencies of magnetization M(T) ferromagnetic Curie temperatures up to 330 K were revealed. EPR spectra in the paramagnetic phase were satisfactory approximated by a single Dysonian line. Temperature dependence of magnetic susceptibility was estimated and paramagnetic Curie temperature was determined. In ferromagnetic phase pronounced distortion and splitting of the EPR spectra on two Dysonian lines were revealed. Using approximation by the Lorenz-type curves with Dysonian terms, temperature dependencies of the main parameters for each absorption line were obtained.

We report on magnetic measurements and X-band electron paramagnetic resonance for Ge1-x-yMnxGdyTe (x=0.15-0.40, y=0, 0.02) single crystals. Ferromagnetic behavior was observed with the Curie temperature TC=70-90 K depending on the alloy composition. Effective magnetic moment peff per Mn ion estimated from the Curie constant increases with increasing x from 2.8 up to 4.3 μB, while saturation magnetization per magnetic ion at 4.2 K gives 1.7-3.4 μB. EPR spectra at low temperatures are described by Dysonian type line, which splits into two lines at T ≈ 150 K. At temperature lower this value we observe distinct anomalies on temperature dependencies of the linewidths and g-factors. In paramagnetic region anomalous broadening of the linewidth with decreasing the temperature is revealed, while the g-factor is practically independent both on temperature and alloy composition.