Expression and Characterization of a GH39 β-Xylosidase II from Caulobacter crescentus

In the present work, the gene xynB2, encoding a ??-xylosidase II of the Glycoside Hydrolase 39 (GH39) family, of Caulobacter crescentus was cloned and successfully overexpressed in Escherichia coli DH10B. The recombinant protein (CcXynB2) was purified using nickel-Sepharose affinity chromatography, with a recovery yield of 75.5?%. CcXynB2 appeared as a single band of 60?kDa on a sodium dodecyl sulfate polyacrylamide gel and was recognized by a specific polyclonal antiserum. The predicted CcXynB2 protein showed a high homology with GH39 ??-xylosidases of the genus Xanthomonas. CcXynB2 exhibited an optimal activity at 55?°C and a pH of 6. CcXynB2 displayed stability at pH values of 4.5?C7.5 for 24?h and thermotolerance up to 50?°C. The K _M and V _Max values were 9.3?±?0.45?mM and 402?±?19???mol?min^?1 for ??-nitrophenyl-??-d-xylopyranoside, respectively. The purified recombinant enzyme efficiently produced reducing sugars from birchwood xylan and sugarcane bagasse fibers pre-treated with a purified xylanase. As few bacterial GH39 family ??-xylosidases have been characterized, this work provides a good contribution to this group of enzymes.     

Growth of c‐axis‐oriented aluminum nitride thin films onto different substrates and buffer layers

The growth of aluminum nitride thin films onto various substrates (glass, flexible polyimide, or silicon) and onto different buffer layers (Au, Nb, Cu, Ag, Co, Fe, NiFe, or IrMn) is reported. Samples grown on IrMn, Co, NiFe, Nb, or Au show smooth surfaces. This same smooth quality is observed in samples grown at a lower 200 °C temperature directly on glass, Si, or flexible polyimide. In applications where thin and smooth piezoelectric films are necessary, c‐axis‐oriented AlN can be grown onto a wide range of different surfaces: conducting, insulating, ferromagnetic, antiferromagnetic, or flexible. Copyright © 2014 John Wiley & Sons, Ltd.     

Pneumococcal Predictive Proteins Selected by Microbial Genomic Approach Are Serotype Cross-Reactive and Bind to Host Extracellular Matrix Proteins

Streptococcus pneumoniae is a colonizer of the human nasopharynx, which accounts for most of the community-acquired pneumonia cases and can cause non-invasive and invasive diseases. Current available vaccines are serotype-specific and the use of recombinant proteins associated with virulence is an alternative to compose vaccines and to overcome these problems. In a previous work, we describe the identification of proteins in S. pneumoniae by reverse vaccinology and the genetic diversity of these proteins in clinical isolates. It was possible to purify a half of 20 selected proteins in soluble form. The expression of these proteins on the pneumococcal cells surface was confirmed by flow cytometry. We demonstrated that some of these proteins were able to bind to extracellular matrix proteins and were recognized by sera from patients with pneumococcal meningitis infection caused by several pneumococcal serotypes. In this context, our results suggest that these proteins may play a role in pneumococcal pathogenesis and might be considered as potential vaccine candidates.     

99mTc-labeled bombesin analog for breast cancer identification

Bombesin is a tetradecapeptide that binds specifically to gastrin releasing peptide receptors in humans. Several forms of cancer, including lung, prostate, breast, and colon express receptors for bombesin-like peptides. Radiolabeled bombesin analogs with a high affinity for these receptors might therefore be used for scintigraphic imaging of these tumor types. A truncated bombesin derivative (HYNIC-βAla-Bombesin_(7–14)) was radiolabeled with technetium-99m using EDDA and tricine as coligands. In vitro stability was evaluated in presence of plasma and excess of cysteine. The receptor-binding affinity assays was evaluated in MDA-MB-231 cancer cell line. In addition, in vivo biodistribution was performed in nude mice bearing breast tumor. In vitro assay showed a good affinity for the MDA-MB-231 cell line, showing 20.0 % of internalization at 4 h post-administration. ^99mTc-HYNIC-βAla-Bombesin_(7–14) biodistribution revealed a rapid clearance and a significant renal excretion. In addition, tumor uptake was higher than non-excretory organs, such as the spleen, the liver, and muscles. Tumor-to-muscle and tumor-to-blood ratios for ^99mTc-HYNIC-βAla-Bombesin_(7–14) showed high values at 4 h post-injection (5.34 and 4.55, respectively). Furthermore, blocked studies using cold bombesin peptide were performed, which demonstrated an important decrease in tumor uptake, indicating a tumor specificity for ^99mTc-HYNIC-βAla-Bombesin_(7–14). The ^99mTc-HYNIC-βAla-Bombesin_(7–14) displayed suitable radiochemical characteristics, and adequate affinity to breast tumor cells (MDA-MB-231). Therefore, this analog can be considered as a candidate for the identification of bombesin-positive tumors.     

Certification of a low value electrolytic conductivity solution using traceable measurements

Reliable measurement results of electrolytic conductivity (EC), in particular for low values, must be metrologically traceable and be based on a realistic measurement uncertainty budget. The use of certified reference materials (CRMs) can help to achieve this goal. This paper presents results from all stages of the certification of an EC CRM with a conductivity of 1.5 μS cm^?1, including the preparation of the batch solution and the evaluation of the homogeneity and stability of the bottled CRM. An uncertainty budget is presented for the CRM, including the main contributions from each of these sources. The CRM batch remained stable within its certified uncertainty for more than 1 year.     

Boundary layer solutions to functional elliptic equations

The goal of this paper is to study a class of nonlinear functional elliptic equations using very simple comparison principles. We first construct a nontrivial solution and then study its asymptotic behaviour when the diffusion coefficient goes to 0.     

Target detection beneath foliage using polarimetric synthetic aperture radar interferometry

In this paper, we demonstrate how the new technology of polarimetric synthetic aperture radar (SAR) interferometry can be used to enhance the detection of targets hidden beneath foliage. The key idea is to note that for random volume scattering, the interferometric coherence is invariant to changes in wave polarization. On the other hand, in the presence of a target the coherence changes with polarization. We show that under general symmetry constraints this change is linear in the complex coherence plane. These observations can be used to devise a filter to suppress the returns from foliage clutter while maintaining the signal from hidden targets. We illustrate the algorithm by applying it to coherent L-band SAR simulations of corner reflectors hidden in a forest. The simulations are performed using a voxel-based vector wave propagation and scattering code coupled to detailed structural models of tree architecture. In this way, the spatial statistics and radar signal fluctuations closely match those observed for natural terrain. We demonstrate significant improvements in the detection of hidden targets, which suggests that this technology has great potential for future foliage penetration (FOPEN) applications.