757 research outputs found
Impact behavior of energy absorbing helmet liners with PA12 lattice structures: A computational study
No full textExisting helmets have a significant but limited ability to reduce the severity of brain injury and the fatality rate during motorcycle accidents. Helmet designs with a special focus on reducing head injuries caused by rotational effects have attracted great interest in recent times. This paper uses a computational approach to study the generation of new helmet designs with lattice liners made of polyamide12 (PA12) material. Three design possibilities and three distinct unit cell topologies were used to create the liners as the energy absorbing and dissipating part of the helmet. PA12 lattice samples were additively manufactured and tested under quasi-static and dynamic compression loads. The test data, showing ductile to brittle transition due to strain-rate effects, were used to validate the finite element models of the lattices. Simulations of the linear high energy and oblique impacts on the coupled headform and liner were carried out following the state-of-the-art helmet standard ECE R22.06. The findings of this study suggest that PA12 lattice liners have an excellent capability of reducing peak rotational acceleration. Many liners can outperform the protection levels offered by existing expandable polystyrene foam liners for single impacts, but at the expense of weight. The performance of the liners can be improved by choosing the topology in such a way that the stress can be distributed through the struts. Moreover, a lattice liner having a balanced energy absorption capability and stiffness would perform better than other lattice liners
Corrigendum to “The effect of misoprostol on the removal of endometrial polyps: A pilot clinical trial” [Int J Reprod BioMed 2022; 20: 461-468]
No full textThe authors have been informed of an error that occurred on page 461 in which the family name of the last author (Nasim Tabibnejhad) has been entered incorrectly, which should be corrected as: “Nasim Tabibnejad”. On behalf of the author, the publisher wishes to apologize for this error. The online version of the article has been updated on 20 December 2022 and can be found at https://doi.org/10.18502/ijrm.v20i6.11441
Separating Oil-Water Nanoemulsions using Flux-Enhanced Hierarchical Membranes
No full textMembranes that separate oil-water mixtures based on contrasting wetting properties have recently received significant attention. Separation of nanoemulsions, i.e. oil-water mixtures containing sub-micron droplets, still remains a key challenge. Tradeoffs between geometric constraints, high breakthrough pressure for selectivity, high flux, and mechanical durability make it challenging to design effective membranes. In this paper, we fabricate a hierarchical membrane by the phase inversion process that consists of a nanoporous separation skin layer supported by an integrated microporous layer. We demonstrate the separation of water-in-oil emulsions well below 1 μm in size. In addition, we tune the parameters of the hierarchical membrane fabrication to control the skin layer thickness and increase the total flux by a factor of four. These simple yet robust hierarchical membranes with engineered wetting characteristics show promise for large-scale, efficient separation systems.MIT Energy InitiativeShell Oil CompanyMIT Energy Initiative (Fellowship
Enhancing droplet deposition through in-situ precipitation
No full textRetention of agricultural sprays on plant surfaces is an important challenge. Bouncing of sprayed pesticide droplets from leaves is a major source of soil and groundwater pollution and pesticide overuse. Here we report a method to increase droplet deposition through in-situ formation of hydrophilic surface defects that can arrest droplets during impact. Defects are created by simultaneously spraying oppositely charged polyelectrolytes that induce surface precipitation when two droplets come into contact. Using high-speed imaging, we study the coupled dynamics of drop impact and surface precipitate formation. We develop a physical model to estimate the energy dissipation by the defects and predict the transition from bouncing to sticking. We demonstrate macroscopic enhancements in spray retention and surface coverage for natural and synthetic non-wetting surfaces and provide insights into designing effective agricultural sprays
Targeting the TGF-β signaling pathway for resolution of pulmonary arterial hypertension
No full textYesAberrant transforming growth factor-β (TGF-β) signaling activation is linked to pulmonary arterial hypertension (PAH). BMPR2 mutations perturb the balance between bone morphogenetic protein (BMP) and TGF-β pathways, leading to vascular remodeling, narrowing of the lumen of pulmonary vasculature, and clinical symptoms. This forum highlights the association of the TGF-β pathway with pathogenesis and therapeutic approaches.Research carried out at Nasim laboratories is funded by GrowMedtech, the Royal Society, the Commonwealth Scholarship Commission (CSC) and the University of Bradford (UoB). N.S. is funded by the CSC and C.C.N. is partly funded by the UoB
Bertrand Russell and the Edwardian Philosophers: Constructing the World
No full textThis book demonstrates the influence of an Edwardian 'controversy' on Russell's philosophy of the external world. It brings to our attention a debate that raged amongst Edwardian philosophers on issues of central significance to analytic philosophy before Bertrand Russell entered the discussion. In explaining this Edwardian 'controversy', Nasim Omar combines meticulous scholarly detail with accessibility to argue that the formation of the original strands of 'realism' in British philosophy, usually credited to Russell and Moore, can in fact be linked with a group of Edwardian philosophers that included G.F.Stout and Sir T.P. Nunn. The author re-examines the history of well known notions like 'sense-data' and 'sensibilia', and makes a case for understanding Russell's appeal for the application of 'logical constructions', at first only used as a device in mathematical logic, to the problem of the external world. This switch in the application of logical construction is seen as the rise of a new philosophical method. This book will not only shed light on the relevant doctrines of some of the Edwardian philosophers, but will also demonstrate the considerable role they played in the history of early analytic philosophy
Therapeutic Targeting of BMP and TGF-β Signalling Pathways for the Resolution of Pulmonary Arterial Hypertension
No full textVascular remodelling due to excessive proliferation and apoptosis resistance of
pulmonary arterial smooth muscle (PASMCs) and endothelial cells (ECs) has
been attributed to the pathogenesis of pulmonary arterial hypertension (PAH). It
is an incurable cardiovascular disorder, which leads to right heart failure and
death, if left untreated. Heterozygous germline mutations in the bone
morphogenetic protein receptor type II (BMPR2) have been linked with the
majority (~75%) of the familial form of the disease (HPAH). Mutations in the
BMPR2 gene impinge upon the BMP signalling which perturbs the balance
between BMP and TGF-β pathways leading to the clinical course of the disease.
Current therapies were discovered prior to the knowledge that PAH has
substantial genetic components. Hence, this study aims to identify novel
therapeutic intervention and provide novel insights into how the dysfunctional
BMPRII signalling contributes to the pathogenesis of PAH. This work
demonstrates that cryptolepines and FDA approved drugs (doxorubicin, taxol,
digitoxin and podophyllotoxin) inhibit the excessive proliferation and induce
apoptosis in BMPR2 mutant PASMCs by modulating the BMP and TGF-β
pathways. Moreover, established drug PTC124 has also been tested but has
failed to promote translational readthrough. I have also shown that dysregulated
apoptosis of PASMCs and HPAECs is mediated through the BMPRII-ALK1-BclxL
axis. Finally, the siRNA screen targeting approximately 1000 genes has
identified novel proteins including PPP1CA, IGF-1R, MPP1, MCM5 and SRC
each capable of modulating the BMPRII signalling. Taken together, this study for
the very first time has identified novel compounds with pro-BMP and anti-TGFβ
activities which may provide therapeutic intervention prior to or after the onset of
PAH.Commonwealth Scholarship Commission in the U
Mixed convection heat transfer simulation in a rectangular channel with a variable speed rotational cylinder
No full textPreparation and characterization of silica aerogel immobilized with cyanex 301 for extraction of Zn(II)
No full textLink to publisher's homepage at http://www.ttp.net/A new solid phase extractant silica aerogel immobilized with Cyanex 301 {bis(2,4,4- trimethylpentyl) dithiophosphinic acid} (SAWC) was prepared via a sol- gel method and investigated for the extraction of Zn(II) from aqueous solution by a batch extraction technique. It is found that SAWC can extract about 100% zinc at equilibrium pH 1.7. Prepared SAWC was characterized by FT-IR, BET, EDX and SEM which proved the presence of Cyanex 301 into silica aerogel. Moreover, the material is also easily regenerated and reused in the subsequent removal of Zn(II) in five cycles. Therefore, it could be concluded that it may perform as a solid phase extractant in the extraction of metal ions from the aqueous solution
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