Advancing Alternative Analysis: Integration of Decision Science.

Decision analysis-a systematic approach to solving complex problems-offers tools and frameworks to support decision making that are increasingly being applied to environmental challenges. Alternatives analysis is a method used in regulation and product design to identify, compare, and evaluate the safety and viability of potential substitutes for hazardous chemicals.Assess whether decision science may assist the alternatives analysis decision maker in comparing alternatives across a range of metrics.A workshop was convened that included representatives from government, academia, business, and civil society and included experts in toxicology, decision science, alternatives assessment, engineering, and law and policy. Participants were divided into two groups and prompted with targeted questions. Throughout the workshop, the groups periodically came together in plenary sessions to reflect on other groups' findings.We conclude the further incorporation of decision science into alternatives analysis would advance the ability of companies and regulators to select alternatives to harmful ingredients, and would also advance the science of decision analysis.We advance four recommendations: (1) engaging the systematic development and evaluation of decision approaches and tools; (2) using case studies to advance the integration of decision analysis into alternatives analysis; (3) supporting transdisciplinary research; and (4) supporting education and outreach efforts

Two-stage ZnS Shell Coating on the CuInS2 Quantum Dots for Their Effective Solubilization

High-precision diagnostics is one of the necessary conditions for effective treatment of diseases. Bioimaging is one of the most promising modern methods of tumor diagnosis. High-quality luminophores are necessary for effective bio-imaging. CuInS2(CIS) quantum dots (QDs) are very promising luminophores for these applications due to their low toxicity and long-term stability of their properties. Two batches of CIS QDs with different positions of the luminescence maximum have been obtained. The position of the luminescence maximum can be controlled by changing the Cu to In ratio; a decrease in this ratio cause a blue shift of the luminescence. The standard procedure of CIS synthesis yields QDs covered with thiols, which form strong bonds with the surface and prevent the ligand exchange; hence, it is very hard to adapt CIS QDs for biological tasks using the standard hydrophobic to hydrophilic ligand exchange procedure. We have developed a two-stage shell coating procedure yielding CIS QDs covered with amines, which is suitable for ligand exchange; hence,the resultant QDs can be adapted for modern biological and medical applications. Keywords: Quantum dots, CuInS2, solubilization

Panarchy use in environmental science for risk and resilience planning

Environmental sciences have an important role in informing sustainable management of built environments by providing insights about the drivers and potentially negative impacts of global environmental change. Here, we discuss panarchy theory, a multi-scale hierarchical concept that accounts for the dynamism of complex socio-ecological systems, especially for those systems with strong cross-scale feedbacks. The idea of panarchy underlies much of system resilience, focusing on how systems respond to known and unknown threats. Panarchy theory can provide a framework for qualitative and quantitative research and application in the environmental sciences, which can in turn inform the ongoing efforts in sociotechnical resilience thinking and adaptive and transformative approaches to managemen

Large-scale Synthesis of Monodisperse PbS Quantum Dots

 PbS quantum dots (QDs) are a promising material for designing of modern solar energy convertors. Yet, their reproducible synthesis is still intractable, since typical methods do not allow controlling the growth of PbS nanocrystals due to the high reaction rates. Here we propose the two-step synthetic procedure, which allows controlling precisely nanocrystal growth on the second stage. The first step allows obtaining small PbS QDs by the standard hot injection method, which are then slowly grown to a desired size on the second stage. By use of this method, we were able to obtain gram-scale batches of PbS QDs with high reproducibility of the photoluminescence properties of the synthesis product. Keywords: PbS quantum dots, nanoparticles growth, infrared luminescenc

The Effect of Quantum Dot Shell Structure on Fluorescence Quenching By Acridine Ligand

The current strategy for the development of advanced methods of tumor treatment focuses on targeted drug delivery to tumor cells. Quantum dot (QD) - semiconductor fluorescent nanocrystal, conjugated with a pharmacological ligand, such as acridine, ensures real-time tracking of the delivery process of the active substance. However, the problem of QD fluorescence quenching caused by charge transfer can arise in the case when acridine is bound to the QD. We found that QD shell structure has a defining role on photoinduced electron transfer from QD on acridine ligand which leads to quenching of QD photoluminescence. We have found that multishell CdSe/ZnS/CdS/ZnS QD structure provides minimal reduction of photoluminescence quantum yield at minimal shell thickness compared to classical thin ZnS or “giant” shells. Thus, CdSe/ZnS/CdS/ZnS core/multishell QD could be an optimal choice for engineering of small-sized acridine-based fluorescent labels for tumor diagnosis and treatment systems. Keywords: Quantum dot, photoluminescence quenching, DNA ligand, acridine derivative

IRGC Resource Guide on Resilience (Volume 2)

Volume 2 of the IRGC Resource Guide on Resilience provides an in-depth and pragmatic evaluation of concepts and methods for resilience-based approaches in contrast to risk-based approaches, as proposed and practised in different domains of science and practice. Adequate articulation of risk and resilience is key to ensure security in systems. The guide also considers possible drawbacks of resilience, such as if efforts to improve resilience diverts attention from core functions of risk management, or from the need to discourage inappropriate risk-seeking behaviour. Some of the papers in Volume 2 also discuss the relevance and role of resilience as a strategy to address the challenges posed by systemic risks that develop in complex adaptive systems (CAS). Such systems are interconnected, with the result that risks can cascade within and between systems. Resilience can help navigate dynamic changes in CAS, as those evolve in response to internal and external shocks and stresses

Fundamental Concepts of Cyber Resilience: Introduction and Overview

Given the rapid evolution of threats to cyber systems, new management approaches are needed that address risk across all interdependent domains (i.e., physical, information, cognitive, and social) of cyber systems. Further, the traditional approach of hardening of cyber systems against identified threats has proven to be impossible. Therefore, in the same way that biological systems develop immunity as a way to respond to infections and other attacks, so too must cyber systems adapt to ever-changing threats that continue to attack vital system functions, and to bounce back from the effects of the attacks. Here, we explain the basic concepts of resilience in the context of systems, discuss related properties, and make business case of cyber resilience. We also offer a brief summary of ways to assess cyber resilience of a system, and approaches to improving cyber resilience.Comment: This is a preprint version of a chapter that appears in the book "Cyber Resilience of Systems and Networks," Springer 201

Optical Properties of Core-Multishell Quantum Dots

During the past decade, colloidal semiconductor nanocrystals or quantum dots (QDs) have become not only a subject of interesting fundamental research, but also a product for real-life applications. Intense activities devoted to enhancement of QDs photoluminescence (PL) quantum yield (QY), starting from early attempts to deposit protective ZnS shells atop CdSe cores, have resulted in novel designs of core-shell QDs with 100% PL QY. In this work we present a detailed analysis of optical properties of core-“multishell” (MS) QDs, whose physical structure is specifically designed to attain maximum localization of excited charge carriers inside luminescent cores, and thereby to achieve 100% PL QY. We have produced samples of core-MS QDs having 3 to 7 shell monolayers, studied the evolution of optical transitions in such QDs during the process of shell deposition, and analyzed the effects of shell thickness on the optical properties of finally obtained QDs. Specifically, studies of PL lifetimes have revealed the possibility of alternative emission mechanism, based on delayed charge carrier transfer from excited outer CdS layer of the multishell into CdSe cores. Keywords: quantum dots, core-shell, multishell, SILA