An investigation into the effect of particle platyness on the strength of granular materials using the discrete element method

It has long been recognised that the macroscopic mechanical behaviour of a granular material depends, to differing extents, on micro-mechanical properties such as the particle size distribution, the particle shape, the inter-particle friction angle and the particle strength. However, a systematic investigation of some of these effects is still lacking. In this paper we focus on particle shape, which is one of the fundamental characteristics of a granular material. We build on previous work that used the axes of an equivalent scalene ellipsoid to characterise particle form, one of the three aspects that define particle shape. (The other two being angularity and roughness.) We use DEM simulations to investigate the effect of particle form, and in particular of particle platyness, on the friction angle of a granular material at critical state. It is found that a deviation of particle shape from that of a sphere leads to higher angles of friction; quantities such as fabric, average rates of particle rotation and interparticle sliding are used to provide insights into the underlying micromechanics

Hypertrophic olivary degeneration and palatal myoclonus from a Streptococcus intermedius infection of the brain: illustrative case

BACKGROUND: Hypertrophic olivary degeneration (HOD) is a rare condition that can occur after disruption of the Guillain-Mollaret triangle. Clinically, HOD can present with palatal myoclonus with or without oculopalatal tremor, which sometimes results in symptomatic dysphagia and/or speech abnormalities. This condition is commonly associated with vascular lesions, with only three prior reported cases of HOD resulting from intracranial abscess. OBSERVATIONS: An otherwise healthy patient developed multiple intracranial abscesses. Biopsy showed gram-positive cocci; however, culture findings were negative. Polymerase chain reaction (PCR) identified Streptococcus intermedius. The patient demonstrated palatal myoclonus and vertical nystagmus, which resulted in persistent mild dysphagia and altered speech intonation. After appropriate antimicrobial therapy with resolution of the enhancing lesions, symptoms persisted. Follow-up imaging demonstrated progressive hypertrophy of the right olive with persistent disruption of the right-sided rubro-olivo fiber pathways. LESSONS: Although HOD classically occurs after vascular insult, it can also be seen as a postinfectious sequela. Despite eradication of the infection, palatal myoclonus and oculopalatal tremor may have a persistent impact on quality of life due to impaired speech and swallowing. This case emphasizes the utility of universal PCR in detecting fastidious organisms as well as diffusion tensor imaging for characterization of disrupted fiber pathways

The epidemiology of pseudallescheriasis complicating transplantation: Nosocomial and community‐acquired infection

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141586/1/myc1990336296.pd

The nitridation of ZnO nanowires

ZnO nanowires (NWs) with diameters of 50 to 250 nm and lengths of several micrometres have been grown by reactive vapour transport via the reaction of Zn with oxygen on 1 nm Au/Si(001) at 550°C under an inert flow of Ar. These exhibited clear peaks in the X-ray diffraction corresponding to the hexagonal wurtzite crystal structure of ZnO and a photoluminescence spectrum with a peak at 3.3 eV corresponding to band edge emission close to 3.2 eV determined from the abrupt onset in the absorption-transmission through ZnO NWs grown on 0.5 nm Au/quartz. We find that the post growth nitridation of ZnO NWs under a steady flow of NH3 at temperatures ≤600°C promotes the formation of a ZnO/Zn3N2 core-shell structure as suggested by the suppression of the peaks related to ZnO and the emergence of new ones corresponding to the cubic crystal structure of Zn3N2 while maintaining their integrity. Higher temperatures lead to the complete elimination of the ZnO NWs. We discuss the effect of nitridation time, flow of NH3, ramp rate and hydrogen on the conversion and propose a mechanism for the nitridation

Reduced production of bacterial membrane vesicles predicts mortality in ST45/USA600 methicillin-resistant Staphylococcus aureus bacteremia

Immune biomarkers can stratify mortality risk in staphylococcal bacteremia. Microbial biomarkers may provide more consistent signals during early infection. We demonstrate that in ST45/USA600 bacteremia, bacterial membrane vesicle production in vitro predicts clinical mortality (773 vs. 116 RFU, survivors vs. decedents, p \u3c 0.0001). Using a threshold of 301 relative fluorescence units (RFU), the sensitivity and specificity of the membrane vesicles to predict mortality are 78% and 90%, respectively. This platform is facile, scalable and can be integrated into clinical microbiology lab workflows