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

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

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

Redefining risk research priorities for nanomaterials

Chemical-based risk assessment underpins the current approach to responsible development of nanomaterials (NM). It is now recognised, however, that this process may take decades, leaving decision makers with little support in the near term. Despite this, current and near future research efforts are largely directed at establishing (eco)toxicological and exposure data for NM, and comparatively little research has been undertaken on tools or approaches that may facilitate near-term decisions, some of which we briefly outline in this analysis. We propose a reprioritisation of NM risk research efforts to redress this imbalance, including the development of more adaptive risk governance frameworks, alternative/complementary tools to risk assessment, and health and environment surveillance

Характеризация сорбционных материалов, содержащих оксиды многовалентных металлов для применения в процессах извлечения лития из солевых растворов

Оскільки літій є одним з найбільш затребуваних матеріалів для виробників електроніки, представляє інтерес розглянути альтернативні джерела його отримання. У статті проаналізовано основні джерела видобутку літію, світові запаси і динаміка його видобутку. Нами розглянута можливість отримання літію з морської води сорбційним методом. Проведена порівняльна характеристика сорбційних матеріалів на основі оксидів багатовалентних металів, визначені параметри їх структури. Методом фазового рентгеноструктурного аналізу встановлено будову сорбентів. Показано, що титан-марганцевий сорбент є композитним матеріалом, що складається з частинок TiO2, рутилу, покритих аморфним MnО2. Методом електронного парамагнітного резонансу встановлено валентний стан марганцевої компоненти в структурі сорбенту. Отримано ізотерми адсорбції літію з розчинів, що моделюють морську воду. Досліджено вплив модифікування сорбційних матеріалів методом іонного апплікування. Показано, що найбільшу сорбційну ємність по іонам Li+ має титан-марганцевий сорбент.Since lithium is one of the most popular materials for the electronics industry, it is of interest to consider alternative sources of its receipt. The article analyzes the main sources of lithium production, global stocks and the dynamics of its production. We have considered the possibility of obtaining lithium from sea water by sorption method. The comparative characteristic of sorption materials based on the multivalent metal oxides was conducted, their structure parameters were determined. By method of X-ray analysis structure of the sorbents was studied. It is shown that the titanium-manganese sorbent is composite material consisting of particles of TiO2, rutile coated with amorphous MnO2. By electron paramagnetic resonance method valence states of manganese component in the sorbent structure were set. Adsorption isotherms from lithium solutions simulating sea water were obtained. The effect of modification of sorption materials by ion application was studied. It is shown that the highest sorption capacity to Li+ ions corresponds to titanium-manganese sorbent.Поскольку литий является одним из самых востребованных материалов для производителей электроники, представляет интерес рассмотреть альтернативные источники его получения. В статье проанализированы основные источники добычи лития, мировые запасы и динамика его добычи. Нами рассмотрена возможность получения лития из морской воды сорбционным методом. Проведена сравнительная характеристика сорбционных материалов на основе оксидов многовалентных металлов, определены параметры их структуры. Методом фазового рентгеноструктурного анализа установлено строение сорбентов. Показано, что титан-марганцевый сорбент является композитным материалом, состоящим из частиц TiO2, рутила, покрытых аморфным MnО2. Методом электронного парамагнитного резонанса установлено валентные состояния марганцевой компоненты в структуре сорбента. Получены изотермы адсорбции лития из растворов моделирующих морскую воду. Исследовано влияние модифицирования сорбционных материалов методом ионного апплицирования. Показано, что наибольшую сорбционную емкость по ионам Li+ имеет титан-марганцевый сорбент

Highly Stable, Water-Soluble CdSe/ZnS/CdS/ZnS Quantum Dots with Additional SiO2 shell

Quantum dots (QDs) are fluorescent nanocrystals extensively used today in research and applications. They attract much interest due to the high photostability and fluorescence quantum yields close to 100%. The best QDs are made by synthesis in organic media, and they have to be transferred into aqueous solutions if biomedical applications are concerned. An advanced method for rendering QDs water-soluble is to coat them with hydrophilic SiO2 -layer. However, growing a silica shell with a predetermined thickness is a problem, because uncertain values of the molar extinction coefficients (ε) of core/shell QDs made it impossible to calculate precise yields of the chemical reactions involved. Here we suggest an approach to solving this problem by constructing the structural models of per se and silica-coated QDs followed by measuring ε in a course of the QD synthesis, thus carrying out precise quantitative reactions. Proceeding in such a way, we prepared the CdSe/ZnS/CdS/ZnS QDs with the structure predicted by the model and coated by silica shell. Prepared QDs are characterized by a narrow size distribution and the same fluorescence parameters as the original QDs in the organic medium. Developed approach permitted efficient QDs water-solubilisation and preparation of stable nanoparticles for plethora of biomedical applications.     Keywords: Quantum dots, QD, silica shell, core-shel