Engineering the catalytic batchwise synthesis of H2O2 from its elements

Hydrogen peroxide is a versatile oxidizing agent with several industrial applications. It is also one of “greenest”, since its oxidation by-product is only water. The global demand of the peroxide is increasing, due to its recent usage in new large scale oxidation processes, such as the epoxidation of propylene to propylene oxide and the synthesis of caprolactam. Nowadays most of the world production of H2O2 is carried out by the anthraquinone autoxidation process. Though very safe (H2 and O2 are never in direct contact), the costs related to the high energy consumption for the extraction and purification of the peroxide produced, together with the usage and periodic replacement of toxic and expensive solvents, stimulated the interest in new production paths. Among the several alternatives proposed, the most fascinating one is the direct synthesis (DS) from H2 and O2. It is a environmentally friendly process that would be economically profitable for an in-situ production, requiring lower investments and operating costs. During the last thirty years this system has been under intensive study both by industries as well as academia. However, it has not been commercialized yet, mainly because of poor selectivity and safety concerns. While most of the efforts on improving DS must address the catalyst, there are reaction engineering aspects that deserve attention. DS is frequently carried out in solvents other than water, both to improve H2 solubility and isolate the undesired product (H2O). Further, CO2 is used for safety, H2 solubility and H2O2 stability. However, the lack of information about the solubility of the reagents makes it difficult to develop a realistic kinetic description of the reactions involved in the DS process. Hence, the first step of the research presented herein dealt with solubility measurements, at temperatures in the range 268-288 K and pressures between 0.37 and 3.5 MPa. Measurements were focused on H2, i.e. the limiting reagent during the reaction. At all conditions investigated a linear relation between hydrogen partial pressure and concentration was observed. Increasing the temperature resulted in an enhanced H2 solubility at the same H2 partial pressure. At constant H2 fugacity, the presence of CO2 favored the dissolution of hydrogen in the liquid phase. Correlation and generalization of the measurements were provided through an EoS-based thermodynamic model for the estimation of H2 solubility at reaction conditions. A batch apparatus for the direct synthesis of hydrogen peroxide was developed, to carry out activity measurements on new catalysts and develop a quantitative model of the kinetics. Hydrogenation, disproportionation and direct synthesis reactions were studied on a commercial 5 wt.% Pd/C catalysts at temperatures in the range 258-313 K and pressure up to 2 MPa. Separate experiments were performed to highlight the role of each reaction. An enhanced H2O2 production was obtained adopting different H2 feeding policies, although selectivity did not exceeded 30%. A model of the gas bubbling, batch slurry reactor for H2O2 direct synthesis was developed. A sensitivity analysis on the mass transfer coefficients excluded any limitations occurring at experimental conditions. Comparable temperature dependence was observed for H2O production, hydrogenation and disproportionation (activation energies close to 45 kJ mol-1), while H2O2 synthesis had a much lower activation energy (close to 24 kJ mol-1), suggesting that a higher selectivity is achievable at low temperature. Disproportionation reaction had a very limited influence on the overall peroxide production rate, while hydrogenation was the most rapid side reaction. Water formation was significant, prevailing at higher temperatures. Following these results, Pd and PdAu catalysts supported on SBA15 were prepared and investigated for H2O2 direct synthesis. Catalysts were doped with bromine, a promoter in the H2O2 direct synthesis. Productivity and selectivity decreased when bromine was incorporated in the catalysts, suggesting a possible poisoning due to the grafting process. A synergetic effect between Pd and Au was observed both in presence and absence of bromopropylsilane grafting on the catalyst. Three modifiers of the SBA15 support (Al, CeO2 and Ti) were chosen to elucidate the influence of the surface properties on metal dispersion and catalytic performance. Higher productivity and selectivity were achieved incorporating Al into the SBA15 framework, whereas neither Ti nor CeO2 improved H2O2 yields. The enhanced performance observed for the PdAu/Al-SBA15 catalysts was attributed to the increased number of Brønsted acid sites. Supported catalysts were also synthesized depositing Pd on a highly acidic, macroporous PS-DVB resin (Lewtit K2621). Catalysts with active metal content in the range 0.3-5 wt.% were tested batchwise for the direct synthesis of H2O2. Preliminary H2O2 measurements and X-ray photoelectron spectroscopy (XPS) analysis revealed that the reduced form of Pd was more selective than PdO towards the peroxide. Transmission electron microscopy (TEM) images showed that smaller nanoclusters favored the production of H2O, likely due to their O-O bond breaking aptitud

The design and analysis of novel integrated phase-change photonic memory and computing devices

The current massive growth in data generation and communication challenges traditional computing and storage paradigms. The integrated silicon photonic platform may alleviate the physical limitations resulting from the use of electrical interconnects and the conventional von Neuman computing architecture, due to its intrinsic energy and bandwidth advantages. This work focuses on the development of the phase-change all-photonic memory (PPCM), a device potentially enabling the transition from the electrical to the optical domain by providing the (previously unavailable) non-volatile all-photonic storage functionality. PPCM devices allow for all-optical encoding of the information on the crystal fraction of a waveguide-implemented phase-change material layer, here Ge2Sb2Te5, which in turn modulates the transmitted signal amplitude. This thesis reports novel developments of the numerical methods necessary to emulate the physics of PPCM device operation and performance characteristics, illustrating solutions enabling the realization of a simulation framework modelling the inherently three-dimensional and self-influencing optical, thermal and phase-switching behaviour of PPCM devices. This thesis also depicts an innovative, fast and cost-effective method to characterise the key optical properties of phase-change materials (upon which the performance of PPCM devices depend), exploiting the reflection pattern of a purposely built layer stack, combined with a smart fit algorithm adapting potential solutions drawn from the scientific literature. The simulation framework developed in the thesis is used to analyse reported PPCM experimental results. Numerous sources of uncertainty are underlined, whose systematic analysis reduced to the peculiar non-linear optical properties of Ge2Sb2Te5. Yet, the data fit process validates both the simulation tool and the remaining physical assumptions, as the model captures the key aspects of the PPCM at high optical intensity, and reliably and accurately predicts its behaviour at low intensity, enabling to investigate its underpinning physical mechanisms. Finally, a novel PPCM memory architecture, exploiting the interaction of a much-reduced Ge2Sb2Te5 volume with a plasmonic resonant nanoantenna, is proposed and numerically investigated. The architecture concept is described and the memory functionality is demonstrated, underlining its potential energy and speed improvement on the conventional device by up to two orders of magnitude.Engineering and Physical Sciences Research Council (EPSRC

PNG's new information order (in waiting)

The first of three papers presented at the one-day PNG Council of Churches seminar on the Role of the Media in Papua New Guinea at the University of PNG, 19 August 1994

L'anoressia nervosa prepuberale:caratteristiche cliniche all'esordio ed evoluzione.

OBIETTIVI: Scopo di questo lavoro di tesi è indagare le caratteristiche cliniche all’esordio è l’evoluzione dell’Anoressia Nervosa Prepuberale, dal momento che in letteratura sono ben pochi i lavori che trattano questo argomento. Non ci siamo limitati a descrivere un campione di soggetti anoressici in età prepuberale, ma abbiamo confrontato tutti i dati ottenuti in questo campione con quelli ottenuti in un campione di soggetti con stessa diagnosi di AN ma in età postpuberale. Il nostro obiettivo è quello di valutare se i soggetti prepuberi si presentano con un quadro più grave o meno e se hanno un’evoluzione più favorevole o meno rispetto ai soggetti più grandi. RISULTATI: Per quanto riguarda la diagnosi di DCA, nel gruppo delle prepuberi sono molto più frequenti le restrizioni dietetiche rispetto alle abbuffate e alle condotte di eliminazione (come il vomito e l’abuso di lassativi), che sono invece più tipiche delle postpuberi. Al follow-up c’è un netto miglioramento nel gruppo delle PreP: il 40% dei soggetti non presenta più alcun disturbo del comportamento alimentare. Nel gruppo PostP, invece, il miglioramento è meno evidente. Per quanto riguarda l’Asse I, nel gruppo PreP l’80,95% dei soggetti ha un Disturbo dell’Umore contro il 76,19% delle PostP. Tra i disturbi d’ansia il Disturbo d’Ansia Generalizzata è il più frequente in assoluto, ma più frequente nel gruppo PostP che nel gruppo PreP. Subito dopo, in ordine di frequenza, viene il Disturbo d’Ansia di Separazione, molto più frequente nelle PreP che nelle PostP. Gli altri Disturbi d’Ansia (Disturbo Ossessivo-Compulsivo e Fobia Sociale) sono rari sia nel gruppo PreP che nel gruppo PostP. Non ci sono differenze significative tra le caratteristiche del disturbo alimentare nei due gruppi (PreP e PostP). Per quanto riguarda i sintomi depressivi, l’unico dato che risulta statisticamente diverso nei due gruppi è quello relativo alle ideazioni suicidiarie: nel gruppo PreP nessun soggetto presenta ideazioni suicidiarie, mentre nel gruppo PostP 6 soggetti (28,6%) le presentano. Le condizioni psicopatologiche alla prima valutazione sono peggiori nel gruppo PreP rispetto a quelle del gruppo PostP. I nostri dati sembrano mettere in evidenza il gruppo PreP come più disturbato rispetto al PostP, con una maggiore tendenza a sottostimare la propria malattia non solo per quanto riguarda il comportamento anoressico ma anche la quota ansiosa e i sintomi depressivi. Nel gruppo PreP molti dei punteggi ottenuti ai questionari sono significativamente diversi al follow-up rispetto alla prima valutazione: questo dimostrerebbe un miglioramento marcato dell’assetto psicopatologico del gruppo PreP. Non si può dire lo stesso per le PostP: in questo gruppo, nonostante i punteggi siano in linea generale più bassi al follow-up, non ci sono differenze significative tra prima valutazione e follow-up. Per quanto riguarda le complicanze mediche, i risultati ottenuti nel nostro studio dimostrano, in generale, che non ci sono differenze statisticamente significative tra i due gruppi. Nel nostro studio abbiamo riscontrato un’unica correlazione positiva, e solo nelle PostP: quella tra BMI e Pressione Arteriosa. Per concludere, nel nostro campione non abbiamo individuato alcuna stagione di nascita significativamente più frequente delle altre

Young Children (0-8) and Digital Technology - A qualitative study across Europe

It only takes witnessing a few interactions within modern western families to realize how much the experience of childhood has changed. The change comes from different winds blowing on today’s families’ time but certainly, the use of digital technologies peaks out and its impacts on childhood, education, learning and safety has been at question over the last years. Since a very early age, video watching and gaming on a variety of internet-connected devices are among children's favourite activities. Parents see digital technologies as positive and unavoidable, if not necessary, but at the same time, find managing their use challenging. They perceive digital technologies as something that needs to be carefully regulated and controlled. They would appreciate advice on fostering children’s online skills and safety. The document reports on results of a cross-national analysis building on data coming from 234 family interviews with both children and parents, carried out from September 2014 until April 2017 in 21 countries. It exposes the key findings regarding first children’s usage, perceptions of the digital technologies and their digital skills in the home context but also on parents’ perceptions, attitudes, and strategies. Beside the cross-national analysis, a dedicated section provides contextualized snapshots of the study results at national level. It then takes a close up on 38 families in seven countries in which researchers came for a second interview distant of one year in which they focused on monitoring change of context, children and parents’ perceptions, attitudes, and strategies over time. Conclusion reflect on the potential benefits, risks and consequences associated with their (online) interactions with digital technologies and provide recommendations to policymakers, industry, parents and carers.JRC.E.3-Cyber and Digital Citizens' Securit

Biometric Spoofing: A JRC Case Study in 3D Face Recognition

Based on newly available and affordable off-the-shelf 3D sensing, processing and printing technologies, the JRC has conducted a comprehensive study on the feasibility of spoofing 3D and 2.5D face recognition systems with low-cost self-manufactured models and presents in this report a systematic and rigorous evaluation of the real risk posed by such attacking approach which has been complemented by a test campaign. The work accomplished and presented in this report, covers theories, methodologies, state of the art techniques, evaluation databases and also aims at providing an outlook into the future of this extremely active field of research.JRC.G.6-Digital Citizen Securit

Studio dei tratti psicopatici, delle condotte aggressive e dei relativi correlati neuropsicologici in un campione clinico di soggetti con disturbi esternalizzanti in età evolutiva.

I dati contenuti in questo lavoro di tesi sono estratti da un più ampio studio multicentrico al quale sta partecipando il Nostro Istituto (IRCSS Stella Maris di Calambrone) in collaborazione con l'Ospedale Pediatrico Bambino Gesù di Roma. Lo studio si propone di sottotipizzare dal punto di vista psicopatologico e neuropsicologico i vari tipi di aggressività che possono manifestarsi in bambini ed adolescenti con disturbi del comportamento (disturbo oppositivo-provocatorio, disturbo della condotta, disturbo da deficit di attenzione/iperattività). Il nostro obiettivo, inoltre, è di valutare quali implicazioni potrebbe avere la presenza o meno di tratti psicopatici sia dal punto di vista comportamentale/psicopatologico che nel profilo neuropsicologico

An Assessment of Human Resource Development Program in Mozambique's Public Extension Service

Although Mozambique independent in 1975, public agricultural extension was not established until 1987, through the institutionalization of the National Directorate of Rural Development (DNDR). Since its establishment, human resource development has been a priority. Two approaches have been adopted by DNER for the improvement of human resource over time: the first was in-service training (non- formal and formal); and the second was to replace the elementary and certificate extensionists by hiring diploma technicians on contracts. Three evolutionary periods characterize the development of public extension in Mozambique: the establishment phase (1987-1992), the expansion stage (1993-1997), and the unified extension and PROAGRI phase (1998-2004). During each of these three phases DNER has pursued human resource development. Over the period of unified extension and PROAGRI from 1998 to 2004, DNER introduced a number of challenging goals for improving the quality of its human resources. This study was undertaken to evaluate DNER’s accomplishments in human resource development. The study addressed the role of in-service training in strengthening human resources through the acquisition of new knowledge, skills and the development of critical (analytical) thinking. This study covers only the public extension services. The data were collected during January to October 2004. Several sources of information were consulted and a questionnaire was used to collect information from DN ER staff members. The survey was carried out in January and February 2004 in 33 districts of the 66 in which public extension is currently operating. A total of 260 extensionists and supervisors were interviewed out of a total of 664 field staff members. Although human resource development and in-service training are a continuous and dynamic process, this evaluation is an overall assessment of DNER’s human resource program. The study addresses training effectiveness and relevance based on the principal courses offered to the staff over time, especially during the 1999-2004 Extension Master Plan. The results of the study show that DNER achieved impressive results in the acquisition (hiring diploma staff members on contract) of new staff but the challenging goal to have in place only diplomas as frontline extension workers by 2004 was not accomplished. The upgrading plans (1999-2004) were partially accomplished but the plan of upgrading 138 certificate extensionists to diploma level was far below expectations while results on diploma and BSc upgrading were encouraging. Low participation in-service training by staff members is also troubling. Because 35% of the sampled extensionists are still from secondary schools, special attention must be given to upgrading the knowledge and skills of those agents. One of the most important findings of the survey was the general lack of knowledge of technical messages on land preparation, soil erosion and use of fertilizers, weeding, crop pests and diseases, livestock health information and emerging issues such as irrigation, processing and marketing. Basic information needs to be collected by agricultural economists on the economics of complex interventions such as the use of treadle pumps, conservation farming and processing. Attention should be given to upgrading the technical knowledge and skills of extension staff at all levels.Dissertation (MSc)--University of Pretoria, 2007.Agricultural Economics, Extension and Rural Developmentunrestricte

Crescimento de Pinus taeda L. submetido a diferentes tipos e intensidades de desbaste

TCC(graduação) - Universidade Federal de Santa Catarina. Campus Curitibanos. Engenharia Florestal.O presente trabalho teve como objetivo avaliar a resposta em crescimento após 5 anos da realização de diferentes tipos e intensidades de desbaste em um plantio de Pinus taeda. Aos 7 anos a floresta recebeu quatro diferentes tipos/intensidades de desbaste: desbaste seletivo por baixo (25% de redução em relação ao número de árvores) + sistemático na 5ª linha (20%), desbaste seletivo pelo alto (25%) + sistemático na 5ª linha (20%), desbaste seletivo pelo alto (35%) + sistemático na 10ª linha (10%) e desbaste somente pelo alto (60%). A partir de então, a floresta foi inventariada todos os anos, até os 12 anos de idade, cinco anos após a intervenção. Foram analisadas variáveis dendrométricas como, o número de árvores por hectare (N), diâmetro quadrático médio (dg), diâmetro dominante (d100), área basal (G), volume médio individual acima de 8 cm (vmi), volume comercial acima de 8 cm (V) e receita em reais por hectare. Cinco anos após a instalação do experimento, não foi possível detectar diferenças significativas para nenhuma das variáveis dendrométricas avaliadas. O tratamento utilizando o método seletivo por baixo, apresentou resultados, até o momento, por vezes superior ao método seletivo pelo alto, principalmente para variáveis como, área basal (G) e volume comercial acima de 8 cm (V), indicando que até o momento não existem vantagens em utilizar o método seletivo pelo alto. Entretanto, considerando o crescimento acumulado ao longo dos 5 anos, observou-se diferença significativa para a variável de diâmetro dominante (d100), além disso, as variáveis diâmetro quadrático médio (dg) e área basal (G) apresentaram p-valores limítrofes, indicando que diferenças podem ser observadas com o aumento da idade.This study aimed to evaluate the growth response after 5 years of performing different types and intensities of thinning in a Pinus taeda plantation. At 7 years of age, the forest was submitted to four different types/intensities of thinning: low thinning (25% reduction in relation to the number of trees) + systematic thinning in the 5th row (20%), high thinning (25%) + systematic thinning in the 5th line (20%), high thinning (35%) + systematic thinning in the 10th line (10%) and high thinning only (60%). Since then, the forest was inventoried year after year, until 12 years of age, five years after the intervention. Dendrometric variables were analyzed, such as the number of trees per hectare (N), mean squared diameter (dg), dominant diameter (d100), basal area (G), mean individual volume above 8 cm (vmi), commercial volume above 8 cm (V) and revenue in Reais per hectare. Five years after the thinnings were conducted, there were no differences for the dendrometric variables evaluated. The low thinning method, until this moment, delivered often better results in relation to the high thinning method, especially for variables such as basal area (G) and commercial volume above 8 cm (V), indicating that so far there are no advantages in using the high thinning method. However, considering the accumulated growth over the 5 years, there was a significant difference for the dominant diameter variable (d100), in addition, the mean square diameter (dg) and basal area (G) variables had borderline p-values, indicating that differences may be observed in the coming years