Determination of lower-bound ductility for AZ31 magnesium alloy by use of the bulge specimens

Despite the high demand for industrial applications of magnesium, the forming technology for wrought magnesium alloys is not fully developed due to the limited ductility and high sensitivity to the processing parameters. The processing window for magnesium alloys could be significantly widened if the lower-bound ductility (LBD) for a range of stresses, temperature, and strain rates was known. LBD is the critical strain at the moment of fracture as a function of stress state and temperature. Measurements of LBD are normally performed by testing in a hyperbaric chamber, which is highly specialized, complex, and rare equipment. In this paper an alternative approach to determine LBD is demonstrated using wrought magnesium alloy AZ31 as an example. A series of compression tests of bulge specimens combined with finite element simulation of the tests were performed. The LBD diagram was then deduced by backward calculation.

A systematic review of the quality of liver biopsy specimens

Characteristics for an optimal liver biopsy specimen were recently defined as 20 to 25 mm long and/or containing more than 11 complete portal tracts (CPTs). A systematic review of percutaneous liver biopsy (PLB) and transjugular liver biopsy (TJLB) series yielded only 32 PLB studies in which these characteristics were evaluated: mean ± SD length, 17.7 ± 5.8 mm and number of CPTs, 7.5 ± 3.4; and 15 TJLB studies: mean ± SD length, 13.5 ± 4.5 mm and number of CPTs, 6.8 ± 2.3. Studies of sampling heterogeneity and intraobserver and interobserver variability also used inadequate specimens by present standards. Only 11 (5.3%) of 207 therapeutic studies for chronic hepatitis B and C documented length and/or number of CPTs. Of the current 12 studies evaluating noninvasive fibrosis tests, only 8 documented length or number of CPTs, and only 1 documented length and number of CPTs. New studies are needed based on adequate liver biopsy samples to provide reliable estimation of grading and staging in chronic liver disease.

New and improved molecular sexing methods for museum bird specimens

We present two new avian molecular sexing techniques for nonpasserine and passerine birds (Neognathae), which are more suitable for use with museum specimens than earlier methods. The technique for nonpasserines is based on a new primer (M5) which, in combination with the existing P8 primer, targets a smaller amplicon in the CHD1 sex-linked gene than previously. Primers targeting ATP5A1, an avian sex-linked gene not previously used for sex identification, were developed for passerines. Comprehensive testing across species demonstrated that both primer pairs sex a range of different species within their respective taxonomic groups. Rigorous evaluation of each method within species showed that these permitted sexing of specimens dating from the 1850s. For corn bunting museum specimens, the ATP5A1 method sexed 98% of 63 samples (1857–1966). The M5/P8 CHD1 method was similarly successful, sexing 90% of 384 moorhen specimens from six different museum collections (1855–2001). In contrast, the original P2/P8 CHD1 sexing method only identified the sex of less than half of 111 museum moorhen samples. In addition to dried skin samples, these methods may be useful for other types of material that yield degraded or damaged DNA, and are hence potential new sexing tools for avian conservation genetics, population management and wildlife forensics.