Solvent extraction is one of the methods available for the decontamination of sensitive equipments that are contaminated with chemical warfare agents. The efficiency of extraction method have been verified on the samples, (steel or rubber) that have been contaminated with drops of mustard gas. These samples have been inserted into the extraction flow cell through which solvent (ethoxynonafluorobutane - HFE-7200) flowed. The solvent was sampled in the time intervals. These samples of solvent were analysed for the concentration of mustard gas. Process of extraction was monitored for the three operational factors (the solvent flow rate, temperature and the ultrasound power) and for three different situations (dissolution of drops of mustard gas, mustard gas desorption from the structure of the sample and dissolve drops of mustard gas with the subsequent desorption from the sample). The development of the decontamination process in time was found to consist of two stages. In the first stage the rapid dissolution of the liquid part of mustard gas in a solvent and in the second phase was such as mustard desorption from the structure of the sample and this phase was considerably slower. Extraction is to accelerate increasing the value of the flow of the solvent, the temperature and the performance of the ultrasound. These operational fac-tors have a significant impact on the thickness of the laminar layer of solvent, the solvent replacement coefficient in a cell, diffusion parameters in the process, the viscosity, the solubility of mustard gas in a solvent and the maximum achievable concentration of mustard gas in the rubber sample. The values of adjustable parameters was obtained by mathematical analysis of mathematical model. The progress of extraction under different operational conditions can be predicted by these parameters. The effect of solvents and ultrasound was experimentally verified for selected equipments of computing and communication technology. The possibility of separation of chemical warfare agents from the solvent was verified too.

No description available.

Metal-organic frameworks (MOFs) are a class of hybrid materials that offer a promising platform for a range of catalytic reactions. Due to their complex structure, MOFs offer unique opportunities to serve as novel catalysts, or as host to improve the properties of previously studied species. However, while other catalytic approaches have been studied for many decades, the recency of their discovery means that significant work is still needed to develop MOFs as a viable option for large scale application. Herein, we aimed to advance the field of MOFs as both novel catalysts, and as host platforms for other catalytic species. To this end, we studied synthetic pathways to produce favorable MOF properties such as higher porosity and active site concentration through introduction of defects and macromorphological control, as well as utilization of molecular catalysts imbedded in the MOF structure for multicomponent, light driven reactivity. Chapter 1 introduces the history MOFs and the pursuit of the stable structures commonly associated with MOF chemistry. The synthesis process for zirconium-based MOFs will be discussed, with specific attention given to the modulated synthesis process which can harnessed to change MOF properties and improve catalysis. Two specific reactions will be introduced which serve as a basis for study in this work. First, the hydrolysis of organophosphate nerve agents by MOFs acting as novel catalysts will be introduced. The mechanism of reaction, as well as previous work in this field will be discussed. Finally, water oxidation as part of artificial photosynthesis through incorporated molecular catalysts will be introduced. Chapter 2 presents a modulator screening study on a zirconium-based MOF, UiO-66. One of the most commonly studied MOFs, UiO-66 provides an excellent platform for synthetic modulation. Particle size and defect level were measured of 26 synthetic variations and synthetic conditions were found to isolate changes in defect level and particle size, which typically change coincident with each other. Hydrolysis of the organophosphate compound dimethyl 4-nitrophenylphosphate (DMNP) was used to study the impact of particle size and defect level on reactivity. The reaction was found to be surface limited, even at high levels of missing linker defects. In Chapter 3, the macromorphology of three zirconium-based MOFs were tuned through synthesis modification. MOF powders and xerogels were prepared and characterized to highlight the desirable properties obtained through the gelation process. The materials were compared in the hydrolysis of DMNP and significant enhancement was observed for UiO-66 and NU-1000 xerogels. This was largely attributed to the introduction of mesoporosity and nanocrystalline particle sizes, which significantly increase the number of reactive sites easily accessible for catalysis. In Chapter 4 the authors examine MOFs as a host for molecular catalysts for use in photoelectrochemical water oxidation. A ruthenium-based catalyst [Ru(tpy)(dcbpy)]2+ was incorporated into UiO-67 through a mixed linker synthesis and grown on a WO3 substrate (Ru-UiO-67/WO3). Previous work from our group demonstrated Ru-UiO-67 retained the catalytic activity as the molecular species, while improving the recyclability of the material. In this work, addition of WO3 as a light harvester allowed for the reaction to be driven at a photoelectrochemical underpotential, a first for MOF-based water oxidation. Finally, Chapter 5 offers a perspective of the field of MOF-based artificial photosynthesis. Particular attention is given to issues of diffusion, selectivity, stability, and moving towards integration of multiple components rather than the study of half-reactions. / Doctor of Philosophy / Catalysts are a key component of chemistry that has a major impact on everyday life. From biological examples to industrial settings, catalysts are used to facilitate chemical conversions to new products and compounds. Because of the high demand, development of new catalysts with improved reactivity is a significant scientific challenge. A new class of materials known as metal-organic frameworks (MOFs) have been recently shown to acts as new catalysts or improve the properties of existing catalysts. Herein, we discuss the use of MOFs as catalysts for both development of new catalysts and improving known species. MOF-based catalysts have been used in a range of reactions from destruction of toxic chemical weapons to the production of renewable energy through artificial photosynthesis. This work is intended to highlight the potential for MOF-based catalysts and the next steps to further realize their potential.

<p><br></p><p dir="ltr">Algorithmic reaction explorations based on transition state searches can now routinely predict relatively short reaction sequences involving small molecules across a variety of chemical domains, including materials degradation, combustion chemistry, battery performance, and biomass conversion. Mature quantum chemistry tools can comprehensively characterize the reactivity of species with efficiency and broad coverage, but consecutive characterizations quickly encounter prohibitive costs of reactant proliferation, spurious characterization of irrelevant intermediates, and compounding uncertainties of quantum chemical calculations deep in a network. Application of these algorithms to deeper chemical reaction network (CRN) exploration still requires the development of more effective, comprehensive, and automated exploration policies. </p><p><br></p><p dir="ltr">This dissertation addresses the challenge of exploring deep chemical reaction networks (CRNs) in complex and chemically diverse systems by introducing Yet Another Kinetic Strategy (YAKS), an automated algorithm designed to minimize the computational costs of deep exploration and maximize coverage of important reaction channels. YAKS demonstrates that microkinetic simulations of the nascent network are cost-effective and able to iteratively build deep networks. Key features of the algorithm are the automatic incorporation of expanded elementary reaction steps, compatibility with short-lived but kinetically important species, and the incorporation of rate uncertainty into the exploration policy. The automatically induced expansion of reaction mechanisms gives YAKS access to important chemistries that other algorithms ignore, while also maintaining the ability to limit expensive forays into kinetically irrelevant regions of the CRN that would stymie previous methods. Instead of conducting a greedy exploration, YAKS biases network topography to probe beyond short-lived but kinetically important species, which enables YAKS to explore important endergonic reactions deep into the CRN. YAKS further induces rate uncertainty into an ensemble of microkinetic simulations, which positively influences intermediate prioritization deep in a network. </p><p><br></p><p dir="ltr">Algorithm effectiveness was validated in a case study of glucose pyrolysis, where the algorithm rediscovers reaction pathways previously discovered by heuristic exploration policies and also elucidates new reaction pathways to experimentally obtained products. The resulting CRN is the first to connect all major experimental pyrolysis products to glucose. Additional case studies are presented that investigate the role of reaction rules, rate uncertainty, and bimolecular reactions. These case studies show that na\"ive exponential growth estimates can vastly overestimate the actual number of kinetically relevant pathways in physical reaction networks. The excellent performance of YAKS demonstrates the ability of automated algorithmic methods to address the gaps outlined above.</p><p><br></p><p dir="ltr">The power of YAKS was then demonstrated on radically distinct chemistry from the validation study, chemical warfare agents (CWAs). Despite the almost uniform ban on the use of chemical agents and the widespread neutralization of stockpiles due to treaties, CWAs continue to pose a grave threat around the world. Rogue states, terrorist organizations, and lone wolf terrorists have all conducted CWA attacks within the past few decades. These circumstances make it necessary to prepare against and forensically evaluate the use of CWAs without direct experimentation. YAKS was applied to elucidate degradation reaction networks of three prominent CWAs, mustard gas (SM, HD), sarin (GB), and VX, and identified a range of possible degradant products of real world use cases. This dissertation also computationally interpreted the most common mechanism of action (MoA) associated with each CWA and examined their hydrolysis networks as a method to neutralize these agents. Additionally, agent stability was evaluated during extended microkinetic modeling in arid and humid scenarios, highlighting the potential for computational simulation approaches to fill a capability gap in the broader field of chemical defense. </p><p><br></p><p dir="ltr">This dissertation advanced automated CRN exploration, but considerable gaps remain. Future research directions include the accuracy gaps of both density functional theory and conformational sampling on energy calculations. Incorporation of machine learning (ML) methods can accelerate the costly reactivity characterization process, but ML models still require vast amounts of data. A recently released dataset comprehensively explored over 175,000 graphically defined reactions of moderately-sized C, H, O, and N containing molecules. While models trained on such data could readily be applied to glucose pyrolysis systems, chemical agents involve a much wider array of chemistry including Cl, S, P, and considerable quantities of radical and charged species. More comprehensive datasets are required to train a general ML model capable of accelerating geometry or energy calculations. Additionally, microkinetic modeling is hindered by software implementations that are unable to explore diverse chemistry such as multiphase reactions. In light of this, further improvements in exploration policies, reaction prediction algorithms, and simulation software make it feasible that CRNs might soon be routinely predictable in many additional contexts.</p>

Metal nanostructures exhibit a wide variety of interesting physical and chemical properties, which can be tailored by altering their size, morphology, composition, and environment. Gold and silver nanostructures have received considerable attention for many decades because of their widespread use in applications such as catalysis, photonics, electronics, optoelectronics, information storage, chemical and biological sensing, surface plasmon resonance and surface-enhanced Raman scattering (SERS) detection. This thesis is composed of three main parts about the synthesis, characterization and SERS applications of shape-controlled and surface modified noble metal nanoparticles. The first part is related to a simple synthesis of shape controlled solid gold, hollow gold, silver, gold-silver core-shell, hollow gold-silver double-shell nanoparticles by applying aqueous solution chemistry. Nanoparticles obtained were used for SERS detection of dye molecules like brilliant cresyl blue (BCB) and crystal violet (CV) in aqueous system. v The second part involves the synthesis of surface modified silver nanoparticles for the detection of dopamine (DA) molecules. Determination of a dopamine molecule attached to a iron-nitrilotriaceticacid modified silver (Ag-Fe(NTA)) nanoparticles by using surface-enhanced resonance Raman scattering (SERRS) was achieved. The Ag-Fe (NTA) substrate provided reproducibility and excellent sensitivity. Experimental results showed that DA was detected quickly and accurately without any pretreatment in nM levels with excellent discrimination against ascorbic acid (AA) (which was among the lowest value reported in direct SERS detection of DA). In the third part, a lanthanide series ion (Eu3+) containing silver nanoparticle was prepared for constructing a molecular recognition SERS substrate for the first time. The procedure reported herein, provides a simple way of achieving reproducible and sensitive SERS spectroscopy for organophosphates (OPP) detection. The sensing of the target species was confirmed by the appearance of an intense SERS signal of the methyl phosphonic acid (MPA), a model compound for nonvolatile organophosphate nerve agents, which bound to the surface of the Ag-Eu3+ nanostructure. The simplicity and low cost of the overall process makes this procedure a potential candidate for analytical control processes of nerve agents.

Thesis (M.S.P.H.)--Uniformed Services University of the Health Sciences, 2006 / Typescript (photocopy)

Chemical weapons are justly considered by the human society as the oldest type of weapons of mass destruction. Unfortunately the same human society has continued to apply and further develop the ancient principles of use of combat chemical substances. The current world, despite all the humanistic efforts to terminate the history of this type of weapons, continues to be physically threatened by their abuse. I must say that studies of the history of chemical weapons are very demanding and comprehensive. The whole process of historic development of these combat means is interconnected by multiple relations and circumstances and unfortunately has been the source of a lot of inconceivable human suffering. That is why I decided to take the courage and thread the path leading to a look back at the past, for I believe that such a retrospective not only reveals stories that are already buried in the distant past and are not needed any more, but also leads to understanding the present, learning a lesson from past mistakes and acquiring a humble approach to life. On the basis of studies of the many available resources I tried to submit in my diploma thesis a complex summary of current as well as historic knowledge of combat chemical substances, their research and testing on humans. While the issue of chemical weapons and wars as such is paid a lot of attention, the issue of chemical weapon testing on people has still been a marginal theme. The abovementioned facts inspired this thesis and I believe that my diploma theses might be beneficial for its readers. My greatest desire and aim was to present to the readers the historic path of application and the related research and testing of chemical weapons. I hope I have processed the theme to be better understandable to the reader, both professional and lay. I tried to proceed systematically and make my thesis interesting to enrich not only me but also its readers.

No description available.

This thesis is dedicated to the topic of the nerve agents with special emphasis on antidotal treatment utilizing application of the auto-injectors. Two methods were used ? literature research and quantitative research. Since this topic covers plenty of information as regards chemical warfare agents and in particular nerve agents these issues were addressed in the theoretical part of the thesis. In the chapter on current status based on literature resources a summary of evolution of the auto-injector is presented; from firsts notes until the situation today. Practical part of the thesis is concentrated on University of Southern Bohemia in ČeskéBudějovice, Faculty of Health and Social Studies students' knowledge in the area of nerve agents. The results of the research were acquired by the method of quantitative research ? questionnaires with 18 questions. With respect to each of the questions a selection of the 2 to 7 answers was offered to the students, whereas in every case only 1 answer was correct. The results were analyzed both with reference to each of the questions and with reference to each of the students. By this method it has been discovered that the respondents have a good knowledge in the area of nerve agents. Furthermore, the practical part of the thesis included an experiment concerning speed with which the respondents were able to apply antidotum with a training auto-injector by themselves with no prior instructions in comparison to how quickly they were able to do the same after being instructed. By this method were tested the quality of the instructions provided to the auto-injectors and its ergonomic qualities (intuitiveness of its application). Recorded times were statistically analyzed and the results, although materially different, were assessed as satisfactory.

Les menaces constantes de terrorisme nécessitent le développement d'instruments permettant de détecter efficacement des agents chimiques de guerre. L'objectif de ce travail était la réalisation d'un spectromètre de masse devant effectuer des analyses de type : LC/ESI-MS et GC/EI-MS, sur des échantillons sous tous les états : solide, liquide, gazeux et qui soit rapide. Une première partie de ce travail a consisté à étudier le fonctionnement du spectromètre de masse LTQ Velos, puis de faire une étude des modes d'injection axiale et radiale des ions par simulation à l'aide du logiciel SIMION. L'étude de l'injection radiale, nous a démontré la faisabilité de ce mode d'injection dans un piège linéaire. Ainsi, lors d'applications spécifiques dans lesquelles l'axe central doit être libéré, le mode d'activation par IRMPD peut être envisagé. Une deuxième partie de ce travail a consisté à modifier la source CI du module ETD en source EI. Trois sources EI (la Thermo, la NERMAG et la source trappe) ont été étudiées afin de déterminer celle qui serait la plus efficace et offrirait un bon compromis en terme de coût et de temps de développement. La source Thermo a été retenue et a ensuite été implémentée dans le module ETD du LTQ Velos qui a été couplé à un GC rapide pour effectuer des tests préliminaires de faisabilité de ce couplage. Ainsi, ces tests ont permis de caractériser le GC/EI-LTQ Velos comme étant capable d'effectuer des analyses en GC/MS rapide (de l'ordre de ? 5 min). Ce GC/MS rapide a ensuite été intégré dans le démonstrateur ainsi que le collecteur aérien chimique et le détecteur TIC et POC. Des essais préliminaires concluants ont été réalisés sur ce démonstrateur. / Constant threats of terrorism require the development of tools to effectively detect chemical warfare agents. The aim of this work was to develop a mass spectrometer capable of performing rapid LC/ESI-MS and GC/EI-MS analyses on samples from all states: solid, liquid and gaseous. The first part of this work was to study the principle of operation of the linear ion trap LTQ Velos, then to study axial and radial ion injection in the linear ion trap by means of computer simulation using SIMION. The feasibility of performing radial ion injection has been demonstrated, thus in specific applications in which the central axis needs to be released, the IRMPD activation mode may be considered. A second part of this work was to adapt the existing ETD module to accommodate EI. Three EI sources (the Thermo, the NERMAG and the trap source) were studied to determine which one would be the most effective and offer a good compromise in terms of cost and development time. The Thermo source has been selected and modified to conduct EI within the ETD module of the LTQ Velos which was interfaced to a fast GC (Heracles II). Preliminary tests characterized the dual pressure ion trap as a mass analyzer for performing rapid GC/MS analyses. The results showed that the GC-LIT with its high scanning speed was able to provide sufficient scans across chromatographic peaks when working in both the conventional and the fast GC modes, and further offered good EI spectral information. This GC/MS was then implemented into the demonstrator as well as the air sampler and the TIC/POC detector. Conclusive preliminary tests have been made on this demonstrator.