Macrodeformation Twins in Single-Crystal Aluminum.

Deformation twinning in pure aluminum has been considered to be a unique property of nanostructured aluminum. A lingering mystery is whether deformation twinning occurs in coarse-grained or single-crystal aluminum at scales beyond nanotwins. Here, we present the first experimental demonstration of macrodeformation twins in single-crystal aluminum formed under an ultrahigh strain rate (∼10^{6} s^{-1}) and large shear strain (200%) via dynamic equal channel angular pressing. Large-scale molecular dynamics simulations suggest that the frustration of subsonic dislocation motion leads to transonic deformation twinning. Deformation twinning is rooted in the rate dependences of dislocation motion and twinning, which are coupled, complementary processes during severe plastic deformation under ultrahigh strain rates.

Optimization of candidate proteins for serological screening of Chlamydia trachomatis infection.

The aim of this study was to optimize candidate antigen proteins for serological screening of Chlamydia trachomatis infection. C. trachomatis positive serum and swabs of genital secretions were collected from 50 patients in the Tianjin Medical University General Hospital, as well as from 30 patients negative for C. trachomatis. Samples were assessed by colloidal gold assay in a sexually transmitted disease clinic as follows: serum antibodies for eight kinds of C. trachomatis immunodominant proteins (Pgp3, CPAF, CT143, CT101, CT694, CT875, CT813, and IncA) were detected, and two traditional gold standards, immunofluorescence and C. trachomatis cell culture of genital secretions, were used for comparison in order to determine the antigen protein combinations with the highest sensitivity and specificity. Of the 50 samples that tested positive for C. trachomatis infection by colloidal gold assay, 44 tested positive by micro-immunofluorescence, whereas 6 tested negative. In contrast, 14 samples tested positive by cell culture, whereas 36 tested negative. Serological results of the immunodominant protein combination of Pgp3, CT694, and CT875 shared positive coincidence rates of 97.73 and 92.86% with C. trachomatis micro-immunofluorescence and cell culture, respectively. No antibodies of the three proteins were detected in the 30 C. trachomatis samples that tested negative by colloidal gold assay; these samples also tested negative in C. trachomatis genital secretion culture. Overall, the combination of the three immunodominant proteins Pgp3, CT694, and CT875 had good sensitivity and specificity for serological screening of C. trachomatis infection, and the process was simple and easy to apply.

Transient x-ray diffraction with simultaneous imaging under high strain-rate loading.

Real time, in situ, multiframe, diffraction, and imaging measurements on bulk samples under high and ultrahigh strain-rate loading are highly desirable for micro- and mesoscale sciences. We present an experimental demonstration of multiframe transient x-ray diffraction (TXD) along with simultaneous imaging under high strain-rate loading at the Advanced Photon Source beamline 32ID. The feasibility study utilizes high strain-rate Hopkinson bar loading on a Mg alloy. The exposure time in TXD is 2-3 µs, and the frame interval is 26.7-62.5 µs. Various dynamic deformation mechanisms are revealed by TXD, including lattice expansion or compression, crystal plasticity, grain or lattice rotation, and likely grain refinement, as well as considerable anisotropy in deformation. Dynamic strain fields are mapped via x-ray digital image correlation, and are consistent with the diffraction measurements and loading histories.

Note: Dynamic strain field mapping with synchrotron X-ray digital image correlation.

We present a dynamic strain field mapping method based on synchrotron X-ray digital image correlation (XDIC). Synchrotron X-ray sources are advantageous for imaging with exceptional spatial and temporal resolutions, and X-ray speckles can be produced either from surface roughness or internal inhomogeneities. Combining speckled X-ray imaging with DIC allows one to map strain fields with high resolutions. Based on experiments on void growth in Al and deformation of a granular material during Kolsky bar/gas gun loading at the Advanced Photon Source beamline 32ID, we demonstrate the feasibility of dynamic XDIC. XDIC is particularly useful for dynamic, in-volume, measurements on opaque materials under high strain-rate, large, deformation.

High speed synchrotron x-ray phase contrast imaging of dynamic material response to split Hopkinson bar loading.

The successful process of amalgamating both the time-resolved imaging capabilities present at the Advanced Photon Source beamline 32ID-B and the proficiency of high-rate loading offered by the split Hopkinson or Kolsky compression/tension bar apparatus is discussed and verification of system effectiveness is expressed via dynamic experiments on various material systems. Single particle sand interaction along with glass cracking during dynamic compression, and fiber-epoxy interfacial failure, ligament-bone debonding, and single-crystal silicon fragmentation due to dynamic tension, were imaged with 0.5 µs temporal resolution and µm-level spatial resolution. Synchrotron x-ray phase contrast imaging of said material systems being loaded with the Kolsky bar apparatus demonstratively depicts the effectiveness of the novel union between these two powerful techniques, thereby allowing for in situ analysis of the interior of the material system during high-rate loading for a variety of applications.

LC method for the determination of oxcarbazepine in pharmaceutical preparations.

A simple and accurate HPLC method for determination of oxcarbazepine (OXC) in a new tablet formulation is described. Chromatographic separation was achieved on a Diamonsil C18 column using a mobile phase consisting of acetonitrile, potassium phosphate monobasic buffer (pH 6.8) and water (36:8:56, v/v) at a flow rate of 1.0 ml/min. Absorbance was monitored at 255 nm where OXC has maximum absorption. The linear range of detection for OXC was from 9.96 to 99.6 microg/ml. The proposed method was validated for selectivity, precision, accuracy and limits of detection and quantitation, etc.