Quantitative Evaluation of Particle Morphology

In geomechanics research shape is most often qualitatively assessed. Various definitions on how to quantify shape have been applied in the literature. This paper assesses the feasibility of applying these definitions to digital images of sand grains. Firstly the way in which size can be calculated from these digital images is discussed, then the sphericity and convexity definitions proposed by Sympatec (2008) are considered. These definitions of sphericity and convexity (SQP, Cx) are relatively easy to apply. By relating SQP and Cx to the qualitative measures of particle shape that are most often used in geotechnical sample description, we argue that there is significant scope to introduce these measures to engineering practice (Altuhafi et al., 2012). We show that distributions of convexity and sphericity obtained in 2D and 3D analyses differ

The relevance of roundness to the crushing strength of granular materials

The prediction of the crushing strength of sands is still an unresolved problem in soil mechanics. For natural sand grains with a regular geometry, Weibull theory has long been adopted to explain the decay of a nominal crushing strength with increasing particle size. The Weibull parameters for a given soil relate strength to size, and, although useful, this is an empirical framework that does not consider the mechanics of crushing. This study aims to provide a more fundamental assessment of the relationship between size, roundness, the stresses induced within the particles, and their crushing strength. A new grain-scale failure criterion is proposed, based on physical experiments on artificial and natural particles, Hertzian analysis and numerical simulations. It considers the physical properties of the particles, including the shape of the grain, as described by the roundness, and both its elastic and plastic features in terms of Young's modulus, Poisson ratio and hardness. The new criterion is suitable for implementation in particle-scale crushing simulations of granular masses, using, for example, the discrete-element method, as well as in improved probabilistic frameworks

Neuroactive steroids influence peripheral myelination: A promising opportunity for preventing or treating age-dependent dysfunctions of peripheral nerves

The process of aging deeply influences morphological and functional parameters of peripheral nerves. The observations summarized here indicate that the deterioration of myelin occurring in the peripheral nerves during aging may be explained by the fall of the levels of the major peripheral myelin proteins [e.g., glycoprotein Po (Po) and peripheral myelin protein 22 (PMP22)]. Neuroactive steroids, such as progesterone (PROG), dihydroprogesterone (5α-DH PROG), and tetrahydroprogesterone (3α,5α-TH PROG), are able to stimulate the low expression of these two myelin proteins present in the sciatic nerve of aged male rats. Since Po and PMP22 play an important physiological role in the maintenance of the multilamellar structure of PNS myelin, we have evaluated the effect of PROG and its neuroactive derivatives, 5α-DH PROG and 3α,5α-TH PROG, on the morphological alterations of myelinated fibers in the sciatic nerve of 22-24-month-old male rats. Data obtained clearly indicate that neuroactive steroids are able to reduce aging-associated morphological abnormalities of myelin and aging-associated myelin fiber loss in the sciatic nerve. © 2003 Elsevier Ltd. All rights reserved.Peer Reviewe

Circulating miR-184 is a potential predictive biomarker of cardiac damage in Anderson–Fabry disease

open21noFunding: This work was supported by the Italian Ministry of Health (PE-2013-02356818) to GCEnzyme replacement therapy (ERT) is a mainstay of treatment for Anderson–Fabry disease (AFD), a pathology with negative effects on the heart and kidneys. However, no reliable biomarkers are available to monitor its efficacy. Therefore, we tested a panel of four microRNAs linked with cardiac and renal damage in order to identify a novel biomarker associated with AFD and modulated by ERT. To this end, 60 patients with a definite diagnosis of AFD and on chronic ERT, and 29 age- and sex-matched healthy individuals, were enrolled by two Italian university hospitals. Only miR-184 met both conditions: its level discriminated untreated AFD patients from healthy individuals (c-statistic = 0.7522), and it was upregulated upon ERT (P < 0.001). On multivariable analysis, miR-184 was independently and inversely associated with a higher risk of cardiac damage (odds ratio = 0.86; 95% confidence interval [CI] = 0.76–0.98; P = 0.026). Adding miR-184 to a comprehensive clinical model improved the prediction of cardiac damage in terms of global model fit, calibration, discrimination, and classification accuracy (continuous net reclassification improvement = 0.917, P < 0.001; integrated discrimination improvement [IDI] = 0.105, P = 0.017; relative IDI = 0.221, 95% CI = 0.002–0.356). Thus, miR-184 is a circulating biomarker of AFD that changes after ERT. Assessment of its level in plasma could be clinically valuable in improving the prediction of cardiac damage in AFD patients.openSalamon I.; Biagini E.; Kunderfranco P.; Roncarati R.; Ferracin M.; Taglieri N.; Nardi E.; Laprovitera N.; Tomasi L.; Santostefano M.; Ditaranto R.; Vitale G.; Cavarretta E.; Pisani A.; Riccio E.; Aiello V.; Capelli I.; La Manna G.; Galie N.; Spinelli L.; Condorelli G.Salamon I.; Biagini E.; Kunderfranco P.; Roncarati R.; Ferracin M.; Taglieri N.; Nardi E.; Laprovitera N.; Tomasi L.; Santostefano M.; Ditaranto R.; Vitale G.; Cavarretta E.; Pisani A.; Riccio E.; Aiello V.; Capelli I.; La Manna G.; Galie N.; Spinelli L.; Condorelli G

RNAi technology and its use in studying the function of nuclear receptors and coregulators

Until just a few years ago, RNA interference (RNAi) technology was restricted to the research fields of plants, C. elegans or Drosophila. The discovery of gene silencing by in vitro synthesized double-stranded RNA (dsRNA) in mammalian cells has made the use of RNAi possible in nearly the entire life science kingdom. DNA vectors delivering small interfering RNA (siRNA) directed by polymerase III or polymerase II promoters to persistently inhibit target genes expression have extended this technology to study in vivo function of these genes. Recently, RNAi has been used as a powerful tool in the functional analysis of nuclear receptors and their coregulators. This short review will cover studies in this area

The influence of fines content and size-ratio on the micro-scale properties of dense bimodal materials

This paper considers factors influencing the fabric of bimodal or gap-graded soils. Discrete element method simulations were carried out in which the volumetric fines content and the size ratio between coarse and fine particles were systematically varied. Frictionless particles were used during isotropic compression to create dense samples; the coefficient of friction was then set to match that of spherical glass beads. The particle-scale data generated in the simulations revealed key size ratios and fines contents at which transitions in soil fabric occur. These transitions are identified from changes in the contact distributions and stress-transfer characteristics of the soils and by changes in the size of the void space between the coarse particles. The results are broadly in agreement with available experimental data on minimum void ratio and contact distributions. The results have implications for engineering applications including assessment of the internal stability of gap-graded soils in embankment dams and flood embankments

Up-Cycling Waste Glass to Minimal Water Adsorption/Absorption Lightweight Aggregate by Rapid Low Temperature Sintering: Optimization by Dual Process-Mixture Response Surface Methodology

Mixed color waste glass extracted from municipal solid waste is either not recycled, in which case it is an environmental and financial liability, or it is used in relatively low value applications such as normal weight aggregate. Here, we report on converting it into a novel glass-ceramic lightweight aggregate (LWA), potentially suitable for high added value applications in structural concrete (upcycling). The artificial LWA particles were formed by rapidly sintering (<10 min) waste glass powder with clay mixes using sodium silicate as binder and borate salt as flux. Composition and processing were optimized using response surface methodology (RSM) modeling, and specifically (i) a combined process-mixture dual RSM, and (ii) multiobjective optimization functions. The optimization considered raw materials and energy costs. Mineralogical and physical transformations occur during sintering and a cellular vesicular glass-ceramic composite microstructure is formed, with strong correlations existing between bloating/shrinkage during sintering, density and water adsorption/absorption. The diametrical expansion could be effectively modeled via the RSM and controlled to meet a wide range of specifications; here we optimized for LWA structural concrete. The optimally designed LWA is sintered in comparatively low temperatures (825-835 °C), thus potentially saving costs and lowering emissions; it had exceptionally low water adsorption/absorption (6.1-7.2% w/wd; optimization target: 1.5-7.5% w/wd); while remaining substantially lightweight (density: 1.24-1.28 g.cm-3; target: 0.9-1.3 g.cm-3). This is a considerable advancement for designing effective environmentally friendly lightweight concrete constructions, and boosting resource efficiency of waste glass flows

Identification of low oxygen-tolerating bacteria in prostate secretions of cancer patients and discussion of possible aetiological significance

MW was in receipt of Barts and The London Charity Equipment Grant for provision of MOLDI-TOF (Grant reference number 486/1193)