Graphene-like two-dimensional ionic boron with double dirac cones at ambient condition

Recently, partially ionic boron (γ-B28) has been predicted and observed in pure boron, in bulk phase and controlled by pressure [Nature, 457 (2009) 863]. By using ab initio evolutionary structure search, we report the prediction of ionic boron at a reduced dimension and ambient pressure, namely, the two-dimensional (2D) ionic boron. This 2D boron structure consists of graphene-like plane and B2 atom pairs, with the P6/mmm space group and 6 atoms in the unit cell, and has lower energy than the previously reported α-sheet structure and its analogues. Its dynamical and thermal stability are confirmed by the phonon-spectrum and ab initio molecular dynamics simulation. In addition, this phase exhibits double Dirac cones with massless Dirac fermions due to the significant charge transfer between the graphene-like plane and B2 pair that enhances the energetic stability of the P6/mmm boron. A Fermi velocity (vf) as high as 2.3 x 106 m/s, which is even higher than that of graphene (0.82 x 106 m/s), is predicted for the P6/mmm boron. The present work is the first report of the 2D ionic boron at atmospheric pressure. The unique electronic structure renders the 2D ionic boron a promising 2D material for applications in nanoelectronics.

The grumpy stump - ultrasound and stump appendicitis

BACKGROUND: Stump appendicitis, the inflammation of an incompletely removed appendix, is a rare clinical presentation. Sonography can be useful in the diagnosis of the condition; by either directly visualising the inflamed stump, or by identifying signs of peri-caecal inflammation that can raise suspicion of the condition. SUMMARY OF WORK: A potential case of stump appendicitis was identified. This prompted a review of literature focused on the incidence of stump appendicitis, utility of ultrasound to identify an inflamed appendiceal stump, and surgical techniques used in appendectomy. SUMMARY OF RESULTS: Stump appendicitis is rare, with as few as 61 cases identified in literature during the last 60 years1. Of the two common techniques of appendectomy, which are ligation and invagination, the former can sometimes leave a residual stump that acts as a potential lumen for the pathophysiological process of appendicitis to recur. Established sonographic criteria for appendicitis also apply to the residual stump. Sonographic secondary signs that suggest the presence of acute appendicitis2 have also been demonstrated in cases of stump appendicitis3, even in the absence of an identifiable stump. DISCUSSION AND CONCLUSIONS: Appendicitis is usually dismissed in patients with a history of appendectomy. Though uncommon, sonographers should be aware of stump appendicitis in post-appendectomy patients that present with right iliac fossa pain from months to decades later. REFERENCE(S) 1. Subramanian A, Liang MK. A 60-year literature review of stump appendicitis: The need for a critical view. Am J Surg; 2012;203(4):503–7. 2. Reddan T, Corness J, Mengersen K, Harden F. Ultrasound of paediatric appendicitis and its secondary sonographic signs: providing a more meaningful finding. J Med Radiat Sci. 2015;DOI: 10.1002/jmrs.154 3. Martínez Chamorro E, Merina Castilla A, Muñoz Fraile B, Koren Fernández L, Borruel Nacenta S. Stump appendicitis: Preoperative imaging findings in four cases. Abdom Imaging. 2013;38(6):1214–9.

Proteomic identification of putative microRNA394 target genes in Arabidopsis thaliana identifies MLP family members critical for normal development

Expression of the F-Box protein Leaf Curling Responsiveness (LCR) is regulated by microRNA, miR394, and alterations to this interplay in Arabidopsis thaliana produce defects in leaf polarity and shoot apical meristem (SAM) organisation. Although the miR394-LCR node has been documented in Arabidopsis, the identification of proteins targeted by LCR F-box itself has proven problematic. Here, a proteomic analysis of shoot apices from plants with altered LCR levels identified a member of the Major Latex Protein (MLP) family gene as a potential LCR F-box target. Bioinformatic and molecular analyses also suggested that other MLP family members are likely to be targets for this post-translational regulation. Direct interaction between LCR F-Box and MLP423 was validated. Additional MLP members had reduction in protein accumulation, in varying degrees, mediated by LCR F-Box. Transgenic Arabidopsis lines, in which MLP28 expression was reduced through an artificial miRNA technology, displayed severe developmental defects, including changes in leaf patterning and morphology, shoot apex defects, and eventual premature death. These phenotypic characteristics resemble those of Arabidopsis plants modified to over-express LCR. Taken together, the results demonstrate that MLPs are driven to degradation by LCR, and indicate that MLP gene family is target of miR394-LCR regulatory node, representing potential targets for directly post-translational regulation mediated by LCR F-Box. In addition, MLP28 family member is associated with the LCR regulation that is critical for normal Arabidopsis development.

Asking the critical questions: An evaluation of social work students' experiences in an international placement

Preparing social work students for the demands of changing social environments and to promote student mobility and interest in overseas employment opportunities have resulted in an increasing demand for international social work placements. The literature describes numerous examples of social work programmes that offer a wide variety of international placements. However, research about the actual benefit of undertaking an overseas placement is scant with limited empirical evidence on the profile of students participating, their experience of the tasks offered, the supervisory practice and the outcomes for students' professional learning and career. This study contributes to the existing body of literature by exploring the relevance of international field placements for students and is unique in that it draws its sample from students who have graduated so provides a distinctive perspective in which to compare their international placement with their other placement/s as well as evaluating what were the benefits and drawbacks for them in terms of their careers, employment opportunities and current professional practice.