Development of Metal Matrix Composites and Related Forming Techniques by Direct Recycling of Light Metals: A Review

In this contribution, researchers have provided a summary of the agricultural and industrial waste recoveries to be deployed as the composite reinforced materials. It covers the work of previous researchers related to this area and addressed the key challenge to overcome for further development and advancement. The major contributions of this work were a comprehensive review on a wide variety of Sever Plastic Deformation (SPD) techniques implementation in development of the waste materials based reinforced metal matrix composite. The waste materials can be derived from either industrial or natural sources. Also, it discusses the range of Metal Matrix Composites (MMCs) applications in engineering and related manufacturing techniques with further emphasized on the process parameters which directly determine the material properties. Some useful suggestions were proposed to the industrialists, academicians and scientists to further improve the performance aspect of Metal Matrix Composites (MMCs) for commercialization reason. Furthermore, industrial and natural waste enhancement materials have been strongly proposed because of their higher reinforced content particulates such as alumina (Al2O3) and silica (SiO2). Also, the mechanical and physical properties are directly influenced by the size, shape and weight-volume friction of the composites as same as the potential reactions between matrixes/reinforced materials interfac

Indoor air concentration from selective laser sintering 3d printer using Virgin Polyamide Nylon (PA12) Powder: a pilot study

Environmental emissions from additive manufacturing (AM) have attracted much attention recently. The capability in fabricating complex part make AM famous in developing prototype and product in various industries, especially in aerospace, medical, automotive, and manufacturing industries. However, the study on emission and exposure mainly focusses on the desktop type such as fused deposition modelling. This study investigates the emission and indoor concentration from powder bed fusion of selective laser sintering (SLS) technologies. Prior to the investigation, virgin PA12 has undergone characterization in terms of morphology, size and thermal analysis. Calibration block using virgin polyamide nylon (PA12) is selected to be printed in this study. Parameters such particulate matter size 2.5 μm (PM 2.5), total volatile organic compound (TVOC), carbon dioxide (CO2), formaldehyde, temperature and relative humidity (RH) are set to be monitored through real-time sampling of 8 hours based on Industry Code of Practice on Indoor Air Quality 2010 by Department Occupational Safety and Health (DOSH) Malaysia. Four phases of the printing process involve are background data, preprinting, during printing and post-printing. Based on the study it was found that PM 2.5 and CO2 exceed the acceptable limit recommended by DOSH Malaysia during the preparation of powder (preprinting) at 1218 ppm and 1070 μg/m3 respectively. Meanwhile TVOC concentration was influenced by the sintered powder temperature and recorded at 0.5 ppm. Temperature, relative humidity and formaldehyde were maintained throughout the SLS process. Mitigation strategies using mechanical ventilation and personal protective equipment (PPE) are recommended to be used to reduce the potential of occupational hazard to the operators

Orbital effect of in-plane magnetic field on quantum transport in chaotic lateral dots

We show how the in-plane magnetic field, which breaks time-reversal and rotational symmetries of the orbital motion of electrons in a heterostructure due to the momentum-dependent inter-subband mixing, affects weak localisation correction to conductance of a large-area chaotic lateral quantum dot and parameteric dependences of universal conductance fluctuations in it.Comment: 4 pages with a figur

An oncogenic role for sphingosine kinase 2

While both human sphingosine kinases (SK1 and SK2) catalyze the generation of the pleiotropic signaling lipid sphingosine 1-phosphate, these enzymes appear to be functionally distinct. SK1 has well described roles in promoting cell survival, proliferation and neoplastic transformation. The roles of SK2, and its contribution to cancer, however, are much less clear. Some studies have suggested an antiproliferative/ pro-apoptotic function for SK2, while others indicate it has a prosurvival role and its inhibition can have anti-cancer effects. Our analysis of gene expression data revealed that SK2 is upregulated in many human cancers, but only to a small extent (up to 2.5-fold over normal tissue). Based on these findings, we examined the effect of different levels of cellular SK2 and showed that high-level overexpression reduced cell proliferation and survival, and increased cellular ceramide levels. In contrast, however, low-level SK2 overexpression promoted cell survival and proliferation, and induced neoplastic transformation in vivo. These findings coincided with decreased nuclear localization and increased plasma membrane localization of SK2, as well as increases in extracellular S1P formation. Hence, we have shown for the first time that SK2 can have a direct role in promoting oncogenesis, supporting the use of SK2-specific inhibitors as anti-cancer agents.Heidi A. Neubauer, Duyen H. Pham, Julia R. Zebol, Paul A.B. Moretti, Amanda L. Peterson, Tamara M. Leclercq, Huasheng Chan, Jason A. Powell, Melissa R. Pitman, Michael S. Samuel, Claudine S. Bonder, Darren J. Creek, Briony L. Gliddon and Stuart M. Pitso

The absence of ABCA1 decreases soluble ApoE levels but does not diminish amyloid deposition in two murine models of Alzheimer disease.

J Biol Chem. 2005 Dec 30;280(52):43243-56. Epub 2005 Oct 5. The absence of ABCA1 decreases soluble ApoE levels but does not diminish amyloid deposition in two murine models of Alzheimer disease. Hirsch-Reinshagen V, Maia LF, Burgess BL, Blain JF, Naus KE, McIsaac SA, Parkinson PF, Chan JY, Tansley GH, Hayden MR, Poirier J, Van Nostrand W, Wellington CL. Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia V4Z 5H5, Canada. Abstract ABCA1, a cholesterol transporter expressed in the brain, has been shown recently to be required to maintain normal apoE levels and lipidation in the central nervous system. In addition, ABCA1 has been reported to modulate beta-amyloid (Abeta) production in vitro. These observations raise the possibility that ABCA1 may play a role in the pathogenesis of Alzheimer disease. Here we report that the deficiency of ABCA1 does not affect soluble or guanidine-extractable Abeta levels in Tg-SwDI/B or amyloid precursor protein/presenilin 1 (APP/PS1) mice, but rather is associated with a dramatic reduction in soluble apoE levels in brain. Although this reduction in apoE was expected to reduce the amyloid burden in vivo, we observed that the parenchymal and vascular amyloid load was increased in Tg-SwDI/B animals and was not diminished in APP/PS1 mice. Furthermore, we observed an increase in the proportion of apoE retained in the insoluble fraction, particularly in the APP/PS1 model. These data suggested that ABCA1-mediated effects on apoE levels and lipidation influenced amyloidogenesis in vivo. PMID: 16207707 [PubMed - indexed for MEDLINE

Relationship of dietary monounsaturated fatty acids to blood pressure: the international study of macro/micronutrients and blood pressure

Objective: In short-term feeding trials, replacement of other macronutrients with monounsaturated fatty acid reduces blood pressure. However, observational studies have not clearly demonstrated a relationship between monounsaturated fatty acid intake and blood pressure. We report associations of monounsaturated fatty acid intake of individuals with blood pressure in a cross-sectional study. Methods: The International Study of Macro/Micronutrients and Blood Pressure is a cross-sectional epidemiologic study of 4,680 men and women ages 40-59 from 17 population samples in China, Japan, United Kingdom, and United States. Nutrient intake data were based on four in-depth multi-pass 24-hour dietary recalls/person and two timed 24-hour urine collections/person. Blood pressure was measured eight times at four visits. Results: Mean monounsaturated fatty acid intake ranged from 8.1 %kcal (China) to 12.2%kcal (United States). With sequential models to control for possible confounders (dietary, other), linear regression analyses showed significant inverse relationship of total monounsaturated fatty acid intake with diastolic blood pressure for all participants; for 2,238 “non-intervened” individuals, the relationship was stronger. Estimated diastolic blood pressure differences with 2-SD higher monounsaturated fatty acids (5.35 %kcal) were -0.82 mm Hg (P<0.05) for all participants and -1.70 mm Hg (P<0.01) for non-intervened individuals. Inverse associations of dietary total oleic acid (main monounsaturated) with blood pressure in non-intervened individuals were not significant, but those of oleic acid from vegetable sources were stronger and significant (P<0.05). Conclusions: Dietary monounsaturated fatty acid intake, especially oleic acid from vegetable sources, may contribute to prevention and control of adverse blood pressure levels in general populations. Condensed Abstract The associations of monounsaturated fatty acid intake of individuals with blood pressure was investigated in a cross-sectional epidemiologic study of 4,680 men and women ages 40-59 from 17 population samples in China, Japan, United Kingdom, and United States. Linear regression analyses showed significant inverse relationship of total monounsaturated fatty acid intake with diastolic blood pressure. Inverse associations of dietary total oleic acid from vegetable sources with blood pressure in non-intervened individuals were stronger and significant. Dietary monounsaturated fatty acid intake, especially oleic acid from vegetable sources, may contribute to prevention and control of adverse blood pressure levels in general populations

Spectral quark model and low-energy hadron phenomenology

We propose a spectral quark model which can be applied to low energy hadronic physics. The approach is based on a generalization of the Lehmann representation of the quark propagator. We work at the one-quark-loop level. Electromagnetic and chiral invariance are ensured with help of the gauge technique which provides particular solutions to the Ward-Takahashi identities. General conditions on the quark spectral function follow from natural physical requirements. In particular, the function is normalized, its all positive moments must vanish, while the physical observables depend on negative moments and the so-called log-moments. As a consequence, the model is made finite, dispersion relations hold, chiral anomalies are preserved, and the twist expansion is free from logarithmic scaling violations, as requested of a low-energy model. We study a variety of processes and show that the framework is very simple and practical. Finally, incorporating the idea of vector-meson dominance, we present an explicit construction of the quark spectral function which satisfies all the requirements. The corresponding momentum representation of the resulting quark propagator exhibits only cuts on the physical axis, with no poles present anywhere in the complex momentum space. The momentum-dependent quark mass compares very well to recent lattice calculations. A large number of predictions and relations can be deduced from our approach for such quantities as the pion light-cone wave function, non-local quark condensate, pion transition form factor, pion valence parton distribution function, etc.Comment: revtex, 24 pages, 3 figure

Making things happen : a model of proactive motivation

Being proactive is about making things happen, anticipating and preventing problems, and seizing opportunities. It involves self-initiated efforts to bring about change in the work environment and/or oneself to achieve a different future. The authors develop existing perspectives on this topic by identifying proactivity as a goal-driven process involving both the setting of a proactive goal (proactive goal generation) and striving to achieve that proactive goal (proactive goal striving). The authors identify a range of proactive goals that individuals can pursue in organizations. These vary on two dimensions: the future they aim to bring about (achieving a better personal fit within one’s work environment, improving the organization’s internal functioning, or enhancing the organization’s strategic fit with its environment) and whether the self or situation is being changed. The authors then identify “can do,” “reason to,” and “energized to” motivational states that prompt proactive goal generation and sustain goal striving. Can do motivation arises from perceptions of self-efficacy, control, and (low) cost. Reason to motivation relates to why someone is proactive, including reasons flowing from intrinsic, integrated, and identified motivation. Energized to motivation refers to activated positive affective states that prompt proactive goal processes. The authors suggest more distal antecedents, including individual differences (e.g., personality, values, knowledge and ability) as well as contextual variations in leadership, work design, and interpersonal climate, that influence the proactive motivational states and thereby boost or inhibit proactive goal processes. Finally, the authors summarize priorities for future researc

Simulation of dimensionality effects in thermal transport

The discovery of nanostructures and the development of growth and fabrication techniques of one- and two-dimensional materials provide the possibility to probe experimentally heat transport in low-dimensional systems. Nevertheless measuring the thermal conductivity of these systems is extremely challenging and subject to large uncertainties, thus hindering the chance for a direct comparison between experiments and statistical physics models. Atomistic simulations of realistic nanostructures provide the ideal bridge between abstract models and experiments. After briefly introducing the state of the art of heat transport measurement in nanostructures, and numerical techniques to simulate realistic systems at atomistic level, we review the contribution of lattice dynamics and molecular dynamics simulation to understanding nanoscale thermal transport in systems with reduced dimensionality. We focus on the effect of dimensionality in determining the phononic properties of carbon and semiconducting nanostructures, specifically considering the cases of carbon nanotubes, graphene and of silicon nanowires and ultra-thin membranes, underlying analogies and differences with abstract lattice models.Comment: 30 pages, 21 figures. Review paper, to appear in the Springer Lecture Notes in Physics volume "Thermal transport in low dimensions: from statistical physics to nanoscale heat transfer" (S. Lepri ed.

2018 American Heart Association Focused Update on Pediatric Advanced Life Support: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

This 2018 American Heart Association focused update on pediatric advanced life support guidelines for cardiopulmonary resuscitation and emergency cardiovascular care follows the 2018 evidence review performed by the Pediatric Task Force of the International Liaison Committee on Resuscitation. It aligns with the International Liaison Committee on Resuscitation's continuous evidence review process, and updates are published when the group completes a literature review based on new published evidence. This update provides the evidence review and treatment recommendation for antiarrhythmic drug therapy in pediatric shock-refractory ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest. As was the case in the pediatric advanced life support section of the "2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care," only 1 pediatric study was identified. This study reported a statistically significant improvement in return of spontaneous circulation when lidocaine administration was compared with amiodarone for pediatric ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest. However, no difference in survival to hospital discharge was observed among patients who received amiodarone, lidocaine, or no antiarrhythmic medication. The writing group reaffirmed the 2015 pediatric advanced life support guideline recommendation that either lidocaine or amiodarone may be used to treat pediatric patients with shock-refractory ventricular fibrillation or pulseless ventricular tachycardia