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Silva B.F.D.,Federal University of Sao Carlos | Perez S.,IDAEA | Gardinalli P.,SERC | Singhal R.K.,Bhabha Atomic Research Center | And 4 more authors.
TrAC - Trends in Analytical Chemistry

The use of metallic nanoparticles (NPs) has exponentially increased in the past decade due to their unique physical and chemical properties at nano-scales [1]. They are added to a myriad of materials and compositions. The key question is not if NPs will enter environmental compartments but rather when. The fate and the stability of NPs in the environment play important roles in determining their environmental distributions and probably control the risk to human health through exposure. Emissions of nanomaterials (NMs) could be intentional or unintentional but occur in particulate, aggregate or embedded states.Despite environmental transformations and changes in their surrounding environment, metallic NPs (M-NPs) tend to exist as stable colloidal aggregates or dispersions. Characterizing NPs and NMs in environmental samples implies determination of their size, their chemical composition and their bulk concentrations in the matrix. Differential size filtration is the most commonly used method to isolate NPs from aqueous matrices. Micro-filtration, nano-filtration, cross-flow filtration, and ultracentrifugation are usually employed to achieve the highest degree of segregation.Chemical characterization of NPs and NMs has traditionally been done using transmission/scanning electron microscopy (TEM/SEM) followed by energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). However, because of their intrinsic limitations, methods have also been combined and validated [e.g., size exclusion and ion chromatography (SEC and IC) with multi-element detection {inductively-coupled plasma mass spectrometry and optical emission spectroscopy (ICP-MS and ICP-OES)].This review describes the current state and the challenges of isolating, segregating and detecting M-NPs in environmental samples. A simple case study shows a common procedure for the analysis of NPs in complex aqueous matrices. © 2011 Elsevier Ltd. Source

Rajamane N.P.,SRM University | Lakshmanan N.,SERC | Jeyalakshmi R.,SRM University
Indian Concrete Journal

Geopolymeric Cement Concretes (GPCCs) are a new class of construction materials where the binder is geopolymer based. These concretes do not have Portland cement and the geopolymeric binding action comes from activation of silica and alumina available in minerals such as fly ash, metakaolin, and ground granulated blast furnace slag (GGBS), etc. The activating medium is a liquid which is highly alkaline and made from various chemicals such as sodium hydroxide, sodium silicate, sodium carbonate, etc. The most commonly used activator solution consists of sodium hydroxide and sodium silicate. Though the concentration of ions such as Na+, SiO3 -2, OH- etc are important for characterisation of activation solutions, physical properties such as viscosity and densities, are easily measurable, more particularly the density testing is simple and straight forward. Therefore, density can be taken as a parameter to characterise the sodium hydroxide and sodium silicate solutions of different concentrations and their combinations. New empirical relationships between density and concentration of the activator solutions are proposed in this paper. Source

Nathan M.,SERC | Nathan M.,University of Birmingham
Research Policy

This paper examines the characteristics of the collaborations between inventors in the United Kingdom (UK) by looking at what types of proximities - geographic, organisational, cognitive, social, and cultural-ethnic - between inventors are prevalent in partnerships that ultimately lead to technological progress. Using a new panel of UK inventors this paper provides an analysis of associations between these 'proximities' and co-patenting. The results show that while collaboration within firms, research centres and universities remains crucial, external networks of inventors are key feature of innovation teams. The analysis shows that external networks are highly dependent on previous social connections, but are generally unconstrained by cultural or cognitive factors. Geographical proximity is also weakly linked with external networks. Our results suggest that innovation policies should, rather than focus on spatial clustering, facilitate the formation of open and diverse networks of inventors. © 2015 Elsevier B.V. All rights reserved. Source

Mannarswamy S.,Hewlett - Packard | Govindarajan R.,SERC
Parallel Architectures and Compilation Techniques - Conference Proceedings, PACT

Software transactional memory (STM) is a promising programming paradigm for shared memory multithreaded programs. In order for STMs to be adopted widely for performance critical software, understanding and improving the cache performance of applications running on STM becomes increasingly crucial, as the performance gap between processor and memory continues to grow. In this paper, we present the most detailed experimental evaluation to date, of the cache behavior of STM applications and quantify the impact of the different STM factors on the cache misses experienced by the applications. We find that STMs are not cache friendly, with the data cache stall cycles contributing to more than 50% of the execution cycles in a majority of the benchmarks. We find that on an average, misses occurring inside the STM account for 62% of total data cache miss latency cycles experienced by the applications and the cache performance is impacted adversely due to certain inherent characteristics of the STM itself. The above observations motivate us to propose a set of specific compiler transformations targeted at making the STMs cache friendly. We find that STM's fine grained and application unaware locking is a major contributor to its poor cache behavior. Hence we propose selective Lock Data co-location (LDC) and Redundant Lock Access Removal (RLAR) to address the lock access misses. We find that even transactions that are completely disjoint access parallel, suffer from costly coherence misses caused by the centralized global time stamp updates and hence we propose the Selective Per-Partition Time Stamp (SPTS) transformation to address this. We show that our transformations are effective in improving the cache behavior of STM applications by reducing the data cache miss latency by 20.15% to 37.14% and improving execution time by 18.32% to 33.12% in five of the 8 STAMP applications. © 2011 IEEE. Source

Nori K.V.,SERC | Natarajan S.,Tata Consultancy Services Ltd. | Nistala P.V.,Tata Consultancy Services Ltd.
ACM International Conference Proceeding Series

In current software engineering practice, there is generally a rather limited connection between software processes and product quality, because the processes are defined at a level of abstraction above the specific product being delivered. This tutorial shows how that connection can be strengthened through the introduction of product-specific processes that identify and capture the collection of tasks needed to produce the specific product. It presents a process framework for product quality achievement that has recently been published as ISO/IEC TS 30103, and implemented successfully on several projects at an IT service organization. The key ideas include establishment of quality specifications for each configuration item, instantiating the organizational processes to the particular product context based on the targeted quality attributes using institutional knowledge, and tracking consistency relationships among project artifacts as concurrent development proceeds. The framework is likely to be of particular interest to project organizations that operate in multiple domains, where there is significant variation in quality goals and the techniques required to achieve quality. Source

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