Effect of a plasmaelectrolytic coating on the strength retention of in vivo and in vitro degraded magnesium implants

The strength decrease in magnesium implants was studied in vitro and in vivo, with and without a protective plasmaelectrolytic coating. In vivo, degradation was examined by implanting rectangular plates on top of the nasal bone of miniature pigs. The presence of gas pockets in the soft tissue surrounding the implants was evaluated with intermediate X-rays and computed X-ray tomography scans before euthanasia. After 12 and 24weeks of in vivo degradation, the large rectangular plates were removed and mechanically tested in three-point bending. In vitro, identical plates were immersed in simulated body fluid for 4, 8 and 12weeks. In vitro and in vivo results showed that onset of gas release can be delayed by the plasmaelectrolytic coating. Mass loss and strength retention during in vivo degradation is about four times slower than during in vitro degradation for the chosen test conditions. Despite the slow degradation of the investigated WE43 alloy, the occurrence of gas pockets could not be completely avoided. Nevertheless, uniformity of degradation and reliable strength retention make this alloy a prime candidate for the use of magnesium in cranio-maxillofacial surgery.

X-ray phase contrast imaging of metallized and non-metallized biological samples

Imaging of biological samples has been performed with a variety of techniques for example electromagnetic waves, electrons, neutrons, ultrasound and X-rays. Also conventional X-ray imaging represents the basis of medical diagnostic imaging, it remains of limited use in this application because it is based solely on the differential absorption of X-rays by tissues. Coherent and bright photon beams, such as those produced by third-generation synchrotron X-ray sources, provide further information on subtle X-ray phase changes at matter interfaces. This complements conventional X-ray absorption by edge enhancement phenomena. Thus, phase contrast imaging has the potential to improve the detection of structures on images by detecting those structures that are invisible with X-ray absorption imaging. Images of a weakly absorbing nylon fibre were recorded in in-line holography geometry using a high resolution low-noise CCD camera at the ESRF in Grenoble. The method was also applied to improve image contrast for images of biological tissues. This paper presents phase contrast microradiographs of vascular tree casts and images of a housefly. These reveal very fine structures, that remain invisible with conventional absorption contrast only.

Total-body digital X-ray in trauma. An experience report on the first operational full body scanner in Europe and its possible role in ATLS

When patients enter our emergency room with suspected multiple injuries, Statscan provides a full body anterior and lateral image for initial diagnosis, and then zooms in on specific smaller areas for a more detailed evaluation. In order to examine the possible role of Statscan in the management of multiply injured patients we implemented a modified ATLS((R)) algorithm, where X-ray of C-spine, chest and pelvis have been replaced by single-total a.p./lat. body radiograph. Between 15 October 2006 and 1 February 2007 143 trauma patients (mean ISS 15+/-14 (3-75)) were included. We compared the time in resuscitation room to 650 patients (mean ISS 14+/-14 (3-75)) which were treated between 1 January 2002 and 1 January 2004 according to conventional ATLS protocol. The total-body scanning time was 3.5 min (3-6 min) compared to 25.7 (8-48 min) for conventional X-rays, The total ER time was unchanged 28.7 min (13-58 min) compared to 29.1 min (15-65 min) using conventional plain radiography. In 116/143 patients additional CT scans were necessary. In 98/116 full body trauma CT scans were performed. In 18/116 patients selective CT scans were ordered based on Statscan findings. In 43/143 additional conventional X-rays had to be performed, mainly due to inadequate a.p. views of fractured bones. All radiographs were transmitted over the hospital network (Picture Archiving and Communication System, PACS) for immediate simultaneous viewing at different places. The rapid availability of images for interpretation because of their digital nature and the reduced need for repeat exposures because of faulty radiography are also felt to be strengths.

Reconstruction of femoro-acetabular offsets using a short-stem

PURPOSE Despite the fact that new and modern short-stems allow bone sparing and saving of soft-tissue and muscles, we still face the challenge of anatomically reconstructing the femoro-acetabular offset and leg length. Therefore a radiological and clinical analysis of a short-stem reconstruction of the femoro-acetabular offset and leg length was performed. METHODS Using an antero-lateral approach, the optimys short-stem (Mathys Ltd, Bettlach, Switzerland) was implanted in 114 consecutive patients in combination with a cementless cup (Fitmore, Zimmer, Indiana, USA; vitamys RM Pressfit, Mathys Ltd, Bettlach, Switzerland). Pre- and postoperative X-rays were done in a standardized technique. In order to better analyse and compare X-ray data a special double coordinate system was developed for measuring femoral- and acetabular offset. Harris hip score was assessed before and six weeks after surgery. Visual analogue scale (VAS) satisfaction, leg length difference and the existence of gluteal muscle insufficiency were also examined. RESULTS Postoperative femoral offset was significantly increased by a mean of 5.8 mm. At the same time cup implantation significantly decreased the acetabular offset by a mean of 3.7 mm, which resulted in an increased combined femoro-acetabular offset of 2.1 mm. Postoperatively, 81.7 % of patients presented with equal leg length. The maximum discrepancy was 10 mm. Clinically, there were no signs of gluteal insufficiency. No luxation occurred during hospitalization. The Harris hip score improved from 47.3 before to 90.1 points already at six weeks after surgery while the mean VAS satisfaction was 9.1. CONCLUSION The analysis showed that loss of femoro-acetabular offset can be reduced with an appropriate stem design. Consequently, a good reconstruction of anatomy and leg length can be achieved. In the early postoperative stage the clinical results are excellent.

Synchrotron X-ray photoabsorption spectroscopy of plasmas

Theoretical X-ray opacities are used in numerous radiative transfer simulations of plasmas at different temperatures and densities, for example astrophysics, fusion, metrology and EUV and X-rays radiation sources. However, there are only a reduced number of laboratories working on the validation of those theoretical results empirically, in particular for high temperature plasmas (mayor que 1eV). One of those limitations comes from the use of broad band EUV- X ray sources to illuminate the plasma which, among other issues, present low reproducibility and repetition rate [1]. Synchrotron radiation facilities are a more appropriate radiation source in that sense, since they provide tunable, reproducible and high resolution photons. Only their ?low? photon intensity for these experiments has prevented researchers to use it for this purpose. However, as new synchrotron facilities improve their photon fluxes, this limitation not longer holds [2]. This work evaluates the experimental requirements to use third generation synchrotron radiation sources for the empirical measurement of opacities of plasmas, proposing a pausible experimental set-up to carry them out. Properties of the laser or discharge generated plasmas to be studied with synchrotron radiation will be discussed in terms of their maximum temperatures, densities and temporal evolution. It will be concluded that there are encouraging reasons to pursue these kind of experiments which will provide with an appropriate benchmark for theoretical opacities

DETERMINAÇÃO DA POSIÇÃO DE REPOUSO DA LÍNGUA EM INDIVÍDUOS COM OCLUSÃO DENTÁRIA NORMAL

O propósito neste estudo foi determinar a posição de repouso da língua em indivíduos com oclusão dentária normal e respiração nasal, por meio de telerradiografias em norma lateral realizadas após a ingestão de bário. A amostra foi composta por 66 radiografias de indivíduos brancos com oclusão dentária normal, sendo 26 do sexo masculino e 40 do sexo feminino, na faixa etária de 12 a 21 anos de idade, procedentes de escolas da região do Grande ABC Paulista. O critério utilizado para diagnóstico da oclusão normal foi As Seis Chaves para a Oclusão Normal preconizadas por Andrews (1972), devendo estar presentes no mínimo quatro das seis chaves, sendo obrigatória a presença da primeira chave de oclusão que é a da relação interarcos. As radiografias foram obtidas com o indivíduo em posição natural da cabeça após a ingestão de contraste de sulfato de bário para evidenciar o controle da língua. Posteriormente foi feito o desenho anatômico das estruturas pesquisadas, marcados os pontos cefalométricos, traçadas as linhas e os planos, e por último obtidas as seguintes medidas lineares: comprimento e altura da língua, distância do dorso da língua na sua porção média até o palato duro e a distância entre a ponta da língua e a incisal do incisivo inferior. Por meio dos resultados encontrados verificou-se que não existe um padrão único de posicionamento de repouso da língua dentro da cavidade oral, em pacientes respiradores nasais, variando muito sua distância até a incisal dos incisivos inferiores, bem como até o palato duro, havendo uniformidade apenas no fato da língua tocar o palato mole em todos os indivíduos da amostra. Não houve relação estatisticamente significante entre a posição de repouso da língua e os biotipos faciais e nem dimorfismo sexual.

DETERMINAÇÃO DA POSIÇÃO DE REPOUSO DA LÍNGUA EM INDIVÍDUOS COM OCLUSÃO DENTÁRIA NORMAL

O propósito neste estudo foi determinar a posição de repouso da língua em indivíduos com oclusão dentária normal e respiração nasal, por meio de telerradiografias em norma lateral realizadas após a ingestão de bário. A amostra foi composta por 66 radiografias de indivíduos brancos com oclusão dentária normal, sendo 26 do sexo masculino e 40 do sexo feminino, na faixa etária de 12 a 21 anos de idade, procedentes de escolas da região do Grande ABC Paulista. O critério utilizado para diagnóstico da oclusão normal foi As Seis Chaves para a Oclusão Normal preconizadas por Andrews (1972), devendo estar presentes no mínimo quatro das seis chaves, sendo obrigatória a presença da primeira chave de oclusão que é a da relação interarcos. As radiografias foram obtidas com o indivíduo em posição natural da cabeça após a ingestão de contraste de sulfato de bário para evidenciar o controle da língua. Posteriormente foi feito o desenho anatômico das estruturas pesquisadas, marcados os pontos cefalométricos, traçadas as linhas e os planos, e por último obtidas as seguintes medidas lineares: comprimento e altura da língua, distância do dorso da língua na sua porção média até o palato duro e a distância entre a ponta da língua e a incisal do incisivo inferior. Por meio dos resultados encontrados verificou-se que não existe um padrão único de posicionamento de repouso da língua dentro da cavidade oral, em pacientes respiradores nasais, variando muito sua distância até a incisal dos incisivos inferiores, bem como até o palato duro, havendo uniformidade apenas no fato da língua tocar o palato mole em todos os indivíduos da amostra. Não houve relação estatisticamente significante entre a posição de repouso da língua e os biotipos faciais e nem dimorfismo sexual.

Caracterização da farinha e do amido isolado da semente de jaca e comportamento reológico de dispersões de amido

O amido é um ingrediente com grande versatilidade de aplicação, e as sementes de jaca, fruto bem difundido, porém pouco aproveitado no Brasil, contêm uma quantidade considerável de amido, sendo ainda fonte de ferro e proteínas. Dessa maneira, os objetivos desse projeto foram a obtenção da farinha de sementes de jaca das variedades mole e dura, a extração do amido utilizando diferentes solventes, e a caracterização de suas propriedades físico-químicas, estruturais e funcionais, bem como a caracterização reológica de dispersões/géis de amido em cisalhamento estacionário e oscilatório. A extração alcalina do amido, além de reduzir significativamente o conteúdo de lipídeos e proteínas, deixando o amido mais puro, promoveu um aumento no teor de amilose e influenciou diretamente as características de inchamento e solubilidade, que apresentaram aumento significativo a partir da temperatura de 70 °C. O aumento da temperatura ocasionou aumento no poder de inchamento e solubilidade, que foi mais pronunciado para a variedade dura, porém esses valores ainda foram considerados baixos (< 17%). Os amidos de sementes de jaca apresentaram grânulos lisos, arredondados e em forma de sino, com formato mais truncado para o amido extraído com hidróxido de sódio. O diâmetro médio dos grânulos de amido foi menor para a extração alcalina, mas sempre com comportamento monomodal. Foi observado um padrão de difração de Raios-X do tipo A para todas as amostras estudadas, e o índice de cristalinidade foi maior para os amidos de sementes de jaca dura, com uma redução estimada em 70% para os amidos obtidos por extração alcalina. A temperatura de gelatinização dos amidos de semente de jaca foi considerada alta (70-100 °C). Os amidos de sementes de jaca dura obtidos na extração com água apresentaram maiores valores de viscosidade de pico e de Breakdown, que representa menor resistência mecânica. A extração com solução de NaOH 0,1 M aumentou a tendência a retrogradação de ~36% (extração aquosa) para 64% e 45% dos amidos de sementes de jaca das variedades mole e dura, respectivamente. Todas as amostras apresentaram comportamento pseudoplástico (n < 1) nas concentrações e temperaturas estudadas, e as dispersões e/ou géis de amido obtidos pela extração alcalina com NaOH apresentaram menor tixotropia e maiores valores de viscosidade. Os modelos Lei da Potência e Herschel Bulkley apresentaram ótimos ajustes aos pontos experimentais (R² ~0,998) para as amostras com 2 e 6 % de amido, respectivamente, porém para a concentração de 5%, o melhor modelo foi função da variedade do fruto usado na obtenção do amido. A dependência das propriedades reológicas com a temperatura foi analisada pela equação de Arrhenius e a energia de ativação foi baixa (15-25 kJ/mol). Quanto ao comportamento viscoelástico, as amostras com 5 e 6% de amido apresentaram comportamento de gel fraco e o aumento da concentração desse polissacarídeo produziu um aumento na elasticidade do material. Os módulos de armazenamento (G\') associados à elasticidade do gel de amido aumentaram durante o seu resfriamento nos ensaios de varredura de temperatura, o que pode ser relacionado à recristalização da amilose durante esse processo e mantiveram-se praticamente constantes no aquecimento isotérmico a 80 °C, sugerindo boa estabilidade térmica do gel. A farinha isolada da semente de jaca pode ser considerada fonte de fibras e apresentou elevados teores de proteínas (~14-16%) e ferro (~85-150 mg/kg). A distribuição do tamanho de partículas da farinha apresentou comportamento bimodal, com grânulos arredondados, presença de fibras e uma matriz proteica envolvendo os grânulos de amido. As propriedades de pasta revelaram maior pico de viscosidade para a farinha de semente de jaca mole. As características encontradas sugerem que os amidos de semente de jaca poderiam ser aplicados na produção de filmes biodegradáveis, e a farinha da semente de jaca poderia ser utilizada em substituição parcial à farinha convencional na fabricação de bolos e biscoitos.

The XMM deep survey in the CDF-S. VI. Obscured AGN selected as infrared power-law galaxies

Context. Accretion onto supermassive black holes is believed to occur mostly in obscured active galactic nuclei (AGN). Such objects are proving rather elusive in surveys of distant galaxies, including those at X-ray energies. Aims. Our main goal is to determine whether the revised IRAC criteria of Donley et al. (2012, ApJ, 748, 142; objects with an infrared (IR) power-law spectral shape), are effective at selecting X-ray type-2 AGN (i.e., absorbed N_H > 10^22 cm^-2). Methods. We present the results from the X-ray spectral analysis of 147 AGN selected by cross-correlating the highest spectral quality ultra-deep XMM-Newton and the Spitzer/IRAC catalogues in the Chandra Deep Field South. Consequently it is biased towards sources with high S/N X-ray spectra. In order to measure the amount of intrinsic absorption in these sources, we adopt a simple X-ray spectral model that includes a power-law modified by intrinsic absorption at the redshift of each source and a possible soft X-ray component. Results. We find 21/147 sources to be heavily absorbed but the uncertainties in their obscuring column densities do not allow us to confirm their Compton-Thick nature without resorting to additional criteria. Although IR power-law galaxies are less numerous in our sample than IR non-power-law galaxies (60 versus 87 respectively), we find that the fraction of absorbed (N_H^intr > 10^22 cm^-2) AGN is significantly higher (at about 3 sigma level) for IR-power-law sources (similar to 2/3) than for those sources that do not meet this IR selection criteria (~1/2). This behaviour is particularly notable at low luminosities, but it appears to be present, although with a marginal significance, at all luminosities. Conclusions. We therefore conclude that the IR power-law method is efficient in finding X-ray-absorbed sources. We would then expect that the long-sought dominant population of absorbed AGN is abundant among IR power-law spectral shape sources not detected in X-rays.

The masses of the neutron and donor star in the high-mass X-ray binary IGR J18027-2016

Aims. We report near-infrared observations of the supergiant donor to the eclipsing high mass X-ray binary pulsar IGR J18027-2016. We aim to determine its spectral type and measure its radial velocity curve and hence determine the stellar masses of the components. Methods. ESO/VLT observations of the donor utilising the NIR spectrograph ISAAC were obtained in the H and K bands. The multi-epoch H band spectra were cross-correlated with RV templates in order to determine a radial solution for the system. Results. The spectral type of the donor was confirmed as B0-1 I. The radial velocity curve constructed has a semi-amplitude of 23.8 ± 3.1 km s-1. Combined with other measured system parameters, a dynamically determined neutron star mass of 1.4  ±  0.2–1.6  ±  0.3 M⊙ is found. The mass range of the B0-B1 I donor was 18.6  ±  0.8–21.8  ±  2.4 M⊙. These lower and upper limits were obtained under the assumption that the system is viewed edge-on (i = 90° with β = 0.89) for the lower limit and the donor fills its Roche lobe (β = 1 with i = 73.1°) for the upper limit respectively.

Circumstellar emission in Be/X-ray binaries of the Magellanic Clouds and the Milky Way

Aims. We study the optical and near-infrared colour excesses produced by circumstellar emission in a sample of Be/X-ray binaries. Our main goals are exploring whether previously published relations, valid for isolated Be stars, are applicable to Be/X-ray binaries and computing the distance to these systems after correcting for the effects of the circumstellar contamination. Methods. Simultaneous UBVRI photometry and spectra in the 3500−7000 Å spectral range were obtained for 11 optical counterparts to Be/X-ray binaries in the LMC, 5 in the SMC and 12 in the Milky Way. As a measure of the amount of circumstellar emission we used the Hα equivalent width corrected for photospheric absorption. Results. We find a linear relationship between the strength of the Hα emission line and the component of E(B − V) originating from the circumstellar disk. This relationship is valid for stars with emission lines weaker than EW ≈ −15   Å. Beyond this point, the circumstellar contribution to E(B − V) saturates at a value ≈0.17   mag. A similar relationship is found for the (V − I) near infrared colour excess, albeit with a steeper slope and saturation level. The circumstellar excess in (B − V) is found to be about five times higher for Be/X-ray binaries than for isolated Be stars with the same equivalent width EW(Hα), implying significant differences in the physical properties of their circumstellar envelopes. The distance to Be/X-ray binaries (with non-shell Be star companions) can only be correctly estimated by taking into account the excess emission in the V band produced by free-free and free-bound transitions in the circumstellar envelope. We provide a simple method to determine the distances that includes this effect.

No anticorrelation between cyclotron line energy and X-ray flux in 4U 0115+634

We report on an outburst of the high mass X-ray binary 4U 0115+634 with a pulse period of 3.6 s in 2008 March/April as observed with RXTE and INTEGRAL. During the outburst the neutron star’s luminosity varied by a factor of 10 in the 3–50 keV band. In agreement with earlier work we find evidence of five cyclotron resonance scattering features at ~10.7, 21.8, 35.5, 46.7, and 59.7 keV. Previous work had found an anticorrelation between the fundamental cyclotron line energy and the X-ray flux. We show that this apparent anticorrelation is probably due to the unphysical interplay of parameters of the cyclotron line with the continuum models used previously, e.g., the negative and positive exponent power law (NPEX). For this model, we show that cyclotron line modeling erroneously leads to describing part of the exponential cutoff and the continuum variability, and not the cyclotron lines. When the X-ray continuum is modeled with a simple exponentially cutoff power law modified by a Gaussian emission feature around 10 keV, the correlation between the line energy and the flux vanishes, and the line parameters remain virtually constant over the outburst. We therefore conclude that the previously reported anticorrelation is an artifact of the assumptions adopted in the modeling of the continuum.

Hot thermal X-ray emission from the Be star HD 119682

We present an analysis of a series of four consecutive Chandra high-resolution transmission gratings observations, amounting to a total of 150 ks, of the Be X-ray source HD 119682 (=1WGA J1346.5–6255), a member of the new class of γ Cas analogs. The Chandra light curve shows significant brightness variations on timescales of hours. However, the spectral distribution appears rather stable within each observation and during the whole campaign. A detailed analysis is not able to detect any coherent pulsation up to a frequency of 0.05 Hz. The Chandra High Energy Transmission Gratings spectrum seems to be devoid of any strong emission line, including Fe Kα fluorescence. The continuum is well described with the addition of two collisionally ionized plasmas of temperatures kT ≈ 15 keV and 0.2 keV, respectively, by the apec model. Models using photoionized plasma components (mekal) or non-thermal components (powerlaw) give poorer fits, providing support for the pure thermal scenario. These two components are absorbed by a single column with N H = (0.20+0.15 –0.03) × 1022 cm–2 compatible with the interstellar value. We conclude that HD 119682 can be regarded as a pole-on γ Cas analog.