Consideraciones geométrico cinéticas sobre reacciones solido-fluido

En este trabajo se muestra que, partiendo de un tratamiento cinético para la reacción entre un sólido poroso y un fluido, el orden de reacción aparente con respecto al sólido debe ser menor que uno. Esto a su vez implica otra conclusión de naturaleza exclusivamente geométrica acerca de la estructura porosa del reactivo sólido. Esta conclusión expresa que la superficie por unidad de volumen hecha adimensional tiene que ser mayor que la concentración adimensional del sólido, tomándose como condición de referencia para adimensionalizar a la del estado inicial.It is shown in this paper that from the kinetic treatment for a reaction between a fluid and a porous solid it can he concluded that the apparent order of reaction for the solid ought to he less than one. This in turn implies another conclusion of a purely geometric nature about the porous structure of the solid rèactant; this conclusion says that the dimensionless surface area of solid reactant per unit volume ought to he greater than the dimensionless concentration of that solid, the reference condition being those of the initial ones

Functionalizable Stereocontrolled Cyclopolyethers by Ring-Closing Metathesis as Natural Polymer Mimics

While complex stereoregular cyclic architectures are commonplace in biomacromolecules, they remain rare in synthetic polymer chemistry, limiting the potential to develop synthetic mimics or advanced materials for biomedical applications. Herein we disclose the formation of a stereocontrolled 1,4‐linked six‐membered cyclopolyether prepared by ring‐closing metathesis (RCM). Ru‐mediated RCM, with careful control of catalyst, concentration and temperature, selectively affords the six‐membered ring cyclopolymer. Under optimized reaction conditions, no metathetical degradation, macrocycle or crosslinking was observed. Post‐polymerization modification by dihydroxylation afforded a novel polymer family encompassing a poly(ethylene glycol) backbone and sugar‐like functionalities ("PEGose"). This strategy also paves the way for using RCM as an efficient method to synthesize other stereocontrolled cyclopolymers

Development of a High Latent Effectiveness Energy Recovery Ventilator with Integration into Rooftop Package Equipment

This Final Report covers the Cooperative Program carried out to design and optimize an enhanced flat-plate energy recovery ventilator and integrate it into a packaged unitary (rooftop) air conditioning unit. The project objective was to optimize the design of a flat plate energy recovery ventilator (ERV) core that compares favorably to flat plate air-to-air heat exchanger cores on the market and to cost wise to small enthalpy wheel devices. The benefits of an integrated unit incorporating an enhanced ERV core and a downsized heating/cooling unit were characterized and the design of an integrated unit considering performance and cost was optimized. Phase I was to develop and optimize the design of a membrane based heat exchanger core. Phase II was the creation and observation of a system integrated demonstrator unit consisting of the Enhanced Energy Recovery Ventilator (EERV) developed in Phase I coupled to a standard Carrier 50HJ rooftop packaged unitary air conditioning unit. Phase III was the optimization of the system prior to commercialization based on the knowledge gained in Phase II. To assure that the designs chosen have the possibility of meeting cost objectives, a preliminary manufacturability and production cost study was performed by the Center for Automation Technologies at RPI. Phase I also included a preliminary design for the integrated unit to be further developed in Phase II. This was to assure that the physical design of the heat exchanger designed in Phase I would be acceptable for use in Phase II. An extensive modeling program was performed by the Center for Building Performance & Diagnostics of CMU. Using EnergyPlus as the software, a typical office building with multiple system configurations in multiple climatic zones in the US was simulated. The performance of energy recovery technologies in packaged rooftop HVAC equipment was evaluated. The experimental program carried out in Phases II and III consisted of fabricating and testing a demonstrator unit using Carrier Comfort Network (CCN) based controls. Augmenting the control signals, CCN was also used to monitor and record additional performance data that supported modeling and conceptual understanding. The result of the testing showed that the EERV core developed in Phase I recovered energy in the demonstrator unit at the expected levels based on projections. In fact, at near-ARI conditions the core recovered about one ton of cooling enthalpy when operating with a three-ton rooftop packaged unit

Metabolomics demonstrates divergent responses of two Eucalyptus species to water stress

Past studies of water stress in Eucalyptus spp. generally highlighted the role of fewer than five “important” metabolites, whereas recent metabolomic studies on other genera have shown tens of compounds are affected. There are currently no metabolite profiling data for responses of stress-tolerant species to water stress. We used GC–MS metabolite profiling to examine the response of leaf metabolites to a long (2 month) and severe (Ψpredawn < −2 MPa) water stress in two species of the perennial tree genus Eucalyptus (the mesic Eucalyptus pauciflora and the semi-arid Eucalyptus dumosa). Polar metabolites in leaves were analysed by GC–MS and inorganic ions by capillary electrophoresis. Pressure–volume curves and metabolite measurements showed that water stress led to more negative osmotic potential and increased total osmotically active solutes in leaves of both species. Water stress affected around 30–40% of measured metabolites in E. dumosa and 10–15% in E. pauciflora. There were many metabolites that were affected in E. dumosa but not E. pauciflora, and some that had opposite responses in the two species. For example, in E. dumosa there were increases in five acyclic sugar alcohols and four low-abundance carbohydrates that were unaffected by water stress in E. pauciflora. Re-watering increased osmotic potential and decreased total osmotically active solutes in E. pauciflora, whereas in E. dumosa re-watering led to further decreases in osmotic potential and increases in total osmotically active solutes. This experiment has added several extra dimensions to previous targeted analyses of water stress responses in Eucalyptus, and highlights that even species that are closely related (e.g. congeners) may respond differently to water stress and re-waterin

Olefin cross metathesis and ring-closing metathesis in polymer chemistry

The use of olefin cross metathesis in preparing functional polymers, through either pre-functionalisation of monomers or post-polymerisation functionalisation is growing in both scope and breadth. The broad functional group tolerance of olefin metathesis offers a wealth of opportunities for introducing a broad range of functional groups into the polymer backbone, tuning polymer properties and expanding potential applications. Similarly, ring-closing metathesis offers the ability to tune the polymer macrostructure and microstructure to similar effect. In this review, we explore the importance of understanding selectivity in olefin cross metathesis in designing functional polymers, the manipulation of this reactivity to prepare (multi)functional polymers, and show how polymer systems can be constructed to favour ring closing and change backbone structure and properties