Correlated Three-Dimensional Imaging of Dislocations: Insights into the Onset of Thermal Slip in Semiconductor Wafers.

Correlated x-ray diffraction imaging and light microscopy provide a conclusive picture of three-dimensional dislocation arrangements on the micrometer scale. The characterization includes bulk crystallographic properties like Burgers vectors and determines links to structural features at the surface. Based on this approach, we study here the thermally induced slip-band formation at prior mechanical damage in Si wafers. Mobilization and multiplication of preexisting dislocations are identified as dominating mechanisms, and undisturbed long-range emission from regenerative sources is discovered.

Optimizing structural and mechanical properties of cryogel scaffolds for use in prostate cancer cell culturing.

Prostate cancer (PCa) currently is the second most diagnosed cancer in men and the second most cause of cancer death after lung cancer in Western societies. This sets the necessity of modelling prostatic disorders to optimize a therapy against them. The conventional approach to investigating prostatic diseases is based on two-dimensional (2D) cell culturing. This method, however, does not provide a three-dimensional (3D) environment, therefore impeding a satisfying simulation of the prostate gland in which the PCa cells proliferate. Cryogel scaffolds represent a valid alternative to 2D culturing systems for studying the normal and pathological behavior of the prostate cells thanks to their 3D pore architecture that reflects more closely the physiological environment in which PCa cells develop. In this work the 3D morphology of three potential scaffolds for PCa cell culturing was investigated by means of synchrotron X-ray computed micro tomography (SXCµT) fitting the according requirements of high spatial resolution, 3D imaging capability and low dose requirements very well. In combination with mechanical tests, the results allowed identifying an optimal cryogel architecture, meeting the needs for a well-suited scaffold to be used for 3D PCa cell culture applications. The selected cryogel was then used for culturing prostatic lymph node metastasis (LNCaP) cells and subsequently, the presence of multi-cellular tumor spheroids inside the matrix was demonstrated again by using SXCµT.

Laboratory-based multi-modal X-ray microscopy and micro-CT with Bragg magnifiers.

We report on the successful demonstration of X-ray phase contrast microscopy and micro computed tomography (CT) with a Bragg magnifier microscope (BMM) in a laboratory setup. The Bragg magnifiers, constituted by two channel-cut crystals in asymmetric diffraction, produced a 15X magnification of the X-ray beam, thus enabling high resolution imaging to be attained. The angular sensitivity of the crystals was used to implement analyzer-based phase contrast imaging: acquiring images at different angular positions and the three parametric images (apparent absorption, differential phase and scattering) have been obtained. Micro-CT, with resolution of about 5 µm is demonstrated with the same system. The main limitations, as well as the ways to mitigate them, are discussed with the aid of the experimental data. The technique demonstrated herein extends high-resolution, multi-modal, x-ray imaging and micro-CT to compact laboratory setups, with the potential of broadening the reach of these techniques outside the community of synchrotron users.

X-ray Bragg magnifier microscope as a linear shift invariant imaging system: image formation and phase retrieval.

We present the theoretical description of the image formation with the in-line germanium Bragg Magnifier Microscope (BMM) and the first successful phase retrieval of X-ray holograms recorded with this imaging system. The conditions under which the BMM acts as a linear shift invariant system are theoretically explained and supported by the experiment. Such an approach simplifies the mathematical treatment of the image formation and reconstruction as complicated propagation of the wavefront onto inclined planes can be avoided. Quantitative phase retrieval is demonstrated using a test sample and a proof of concept phase imaging of a spider leg is also presented.

Potential use of V-channel Ge(220) monochromators in X-ray metrology and imaging.

While channel-cut crystals, in which the diffracting surfaces in an asymmetric cut are kept parallel, can provide beam collimation and spectral beam shaping, they can in addition provide beam compression or expansion if the cut is V-shaped. The compression/expansion ratio depends in this case on the total asymmetry factor. If the Ge(220) diffraction planes and a total asymmetry factor in excess of 10 are used, the rocking curves of two diffractors will have a sufficient overlap only if the second diffractor is tuned slightly with respect to the first one. This study compares and analyses several ways of overcoming this mismatch, which is due to refraction, when the Cu Kα1 beam is compressed 21-fold in a V21 monochromator. A more than sixfold intensity increase was obtained if the matching was improved either by a compositional variation or by a thermal deformation. This provided an intensity gain compared with the use of a simple slit in a symmetrical channel-cut monochromator. The first attempt to overcome the mismatch by introducing different types of X-ray prisms for the required beam deflection is described as well. The performance of the V-shaped monochromators is demonstrated in two applications. A narrow collimated monochromatic beam obtained in the beam compressing mode was used for high-resolution grazing-incidence small-angle X-ray scattering measurements of a silicon sample with corrupted surface. In addition, a two-dimensional Bragg magnifier, based on two crossed V15 channel monochromators in beam expansion mode and tuned by means of unequal asymmetries, was successfully applied to high-resolution imaging of test structures in combination with a Medipix detector.

[Comparative study between sodium stibogluconate BP 88 and meglumine antimoniate in cutaneous leishmaniasis treatment. II. Biochemical and cardiac toxicity]. / Estudo comparativo entre estibogluconato de sódio BP 88 e antimoniato de meglumina no tratamento da leishmaniose cutânea. II. Toxicidade bioquímica e cardíaca.

Toxicity of two antimonial pentavalents were evaluated in 111 patients with cutaneous leishmaniasis. Forty-seven patients received meglumine antimoniate (Group I) and 64 patients, sodium stibogluconate BP 88 (Group II), 20 mg Sbv/kg/day for 20 days. Evaluation of aminotransferases, alkaline phosphatase, amilase, creatinine, urea, urine analysis and electrocardiogram were performed at baseline, on the tenth and twentieth day of treatment. Greater frequency of aminotransferase abnormal levels were observed on the tenth and twentieth days in group II (p < 0.001) and a greater proportion of amilase abnormal levels at the tenth day in the same group (p < 0.001). There was a greater variation of aminotransferases, alkaline phosphatase and amilase in the first ten days of treatment in group II (p < 0.01). On the twentieth day there was a greater variation of aminotransferase levels in group II (p = 0.02 and p = 0.03, respectively). Forty-three percent of group I and 54% of group II showed electrocardiographic abnormalities (p = 0.30).

[A comparative study between sodium stibogluconate BP 88R and meglumine antimoniate in the treatment of cutaneous leishmaniasis. I. The efficacy and safety]. / Estudo comparativo entre estibogluconato de sódio BP 88R e antimoniato de meglumina no tratamento da leishmaniose cutânea: I. Eficácia e segurança.

Efficacy and safety of meglumine antimoniate and sodium stibogluconate BP 88R were compared in cutaneous leishmaniasis treatment in Corte de Pedra, Bahia, an endemic area of leishmaniasis due to Leishmania (Viannia) braziliensis. An open trial was developed with one hundred twenty seven patients who were diagnosed based on clinical criteria and Montenegro's skin test. Fifty eight patients were treated with meglumine antimoniate and 69 received sodium stibogluconate. Both groups received 20 mg/Sbv/kg/day for 20 days. Patients were followed every ten days during treatment and every month thereafter for three months. Sixty two percent patients cured with meglumine antimoniate and 55% cured with sodium stibogluconate (p = 0.42). Headache was more frequent during the first half of treatment in patients receiving sodium stibogluconate (p = 0.026). During the second half, patients treated with sodium stibogluconate showed a greater frequency of myalgia/arthralgia (p = 0.004) and abdominal pain/anorexia (p = 0.004). Three patients treated with sodium stibogluconate had severe side effects.

[Information, attitudes, perceptions, and symbolic representations of AIDS risk and prevention among poor adolescents in Rio de Janeiro, Brazil]. / Grau de informação, atitudes e representações sobre o risco e a prevenção de AIDS em adolescentes pobres do Rio de Janeiro, Brasil.

Four hundred and sixteen poor adolescents of both sexes in Rio de Janeiro were interviewed to study both their level of information and symbolic representations concerning AIDS risk and prevention. The most common source of information on HIV/AIDS was the mass media, particularly television broadcasts. There were doubts and lack of trust regarding official government information on HIV/AIDS. Nearly 70% of the adolescents interviewed believe in HIV transmission through mosquito bites and some 40% through casual contact with wounds or scars or sharing of bathroom utensils. Men seemed to show a greater awareness and autonomy vis- -vis taking initiatives in sex encounters. Attitudes of segregation and exclusion of people with AIDS persist. Lack of prevention was attributed to the impossibility of predicting sexual encounters. The study of symbolic aspects concerning causes of HIV/AIDS displayed broad variability: 80% of the interviewees associated AIDS with excesses in sexual behavior and 40% with homosexual practices. Causal images vary from the predominant view of AIDS as unfair punishment to the less frequent stance considering AIDS as fair punishment (due to sinful behavior). An ambiguous attitude towards transgression (taking as its sterotype the figure of Rio's "malandro", or "streetwise dude") may influence perception of risk and prevention. The paper calls attention to the need for implementing clearer and more direct educational programs. This could be useful for the implementation of culturally sensitive control measures through a reshaping of AIDS symbols. The author recommends a better understanding of the social and economic determinants of disease and reinforcement of the kinds of discourse which empower and raise the self-esteem of poor adolescents by endorsing their civil rights.

Retention of antimony in skin biopsies of leishmaniasis patients after treatment with N-methylglucamine antimoniate.

Leishmaniasis patients were treated with N-methylglucamine antimoniate by intravenous injections of 10 or 20 mg of Sb per kilogram of body weight per day for 10 or 20 days. Digests of skin biopsies taken from the site of lesion before and after treatment were analyzed for antimony by instrumental neutron activation (INAA). The detection limit of the assay was 20 ng, and no Sb could be measured in digests of samples (less than 2.45 mg) taken before treatment. Biopsies taken after injections of Sb showed concentrations in the range of 8.32 to 70.68 ng/g skin. We discuss the usefulness of INAA in the study of Sb in small samples of tissues.