archives@tulane.edu / Enzymes are most powerful catalysts in Nature. Despite decades of research, there are still many open questions surrounding the mechanisms by which enzymes catalyze reactions. Supramolecular chemists have made lots of effort to designing a variety of host molecules to mimic enzymes over the last decade. They aim to understand the power of noncovalent forces and how local environment can be involved in enzymes’ catalytic functions. In our studies, two synthetic water-soluble deep cavity cavitands with different electrostatic potential (EP) that can provide well-defined nano-spaces and can be encapsulated with guests through hydrophobic effect were utilized to investigative the inner guests’ pKa shifts and reactions. First, pKa shifts of thiol guests in deep cavity cavitands have been examined. Here we utilize supramolecular capsules assembled via the hydrophobic effect to encapsulate guests and control their acidity. We found that the greatest impact on the acidity of the bound guests is the position of the acid group in the yotoliter space. Moreover, the nature of the electrostatic potential field (EPF) generated by charged solubilizing groups also plays an important role in acidity, as does the counter ion complexing to the outer surface of the capsule. In summary, these results suggest an electrostatic potential field (EPF) engendered by remote solubilizing groups can affect reactions inside of confined spaces. Second, macrocyclization reactions were investigated in two different electrostatic potential (EP) nano capsules. Here, we quantify these effects through acidity and cyclization rate by the size of the encapsulated guests, which confirmed primary role of Coulombic forces with a simple mathematical model approximating the capsules as Born spheres within a continuum dielectric. These results reveal the reaction rate accelerations possible under Coulombic control and highlight important design criteria for nanoreactors. / 1 / Xiaoyang Cai

Electrostatic self-assembly is a simple, yet versatile and environmentally friendly technique. This technique has been widely used in different areas and recently it has also been used to make nano-structured separating layers for composite polyelectrolyte pervaporation membranes. Non-porous substrates are usually employed for electrostatic self-assembly depositions, but porous substrates have to be used for membrane applications because the composite membranes fabricated with non-porous substrates will have low permeation fluxes. When porous substrates were used to make composite membranes for pervaporation, it was reported that 60 double-layers were needed to get a membrane with suitable separation performance. The deposition of each double-layer needed about one hour, and the fabrication of reported self-assembled membranes with porous substrates was time-consuming and, from an industrial point of view, not practical. <br /><br /> The aim of this work was to make self-assembled composite membranes in a more practical way. The methodology used here is to find appropriate materials and suitable preparation conditions to make self-assembled composite membranes that have less than 10 self-assembled double layers but still have good performance for the dehydration of isopropyl alcohol (IPA)/ water mixtures by pervaporation. <br /><br /> A hydrolyzed polyacrylonitrile (PAN) ultrafiltration membrane is a permanently charged porous material. In this work, this porous material was, for the first time, used as a substrate for the fabrication of a composite self-assembled membrane. It was found that the hydrolyzed porous PAN membranes were good substrates for making self-assembled membranes for pervaporation. <br /><br /> In order to reduce the number of the depositions required for making composite membranes with suitable separation performance, a new deposition technique, concentration-changing deposition technique, has been developed. To obtain more extended conformations of polyelectrolytes to prevent them from going into the pores on a porous substrate, dilute deposition solutions were used for the first several depositions. After these first depositions, the pore size of the porous substrate had been reduced and more concentrated solutions (but still dilute solutions) could be used for the subsequent depositions. By using more concentrated deposition solutions, the number of the polyelectrolyte coils adsorbed by the charged substrate was increased and the thickness of each deposited layer was increased. In this way, the total number of deposition layers needed for a good membrane would be decreased. It has been proved in this work that the number of deposition layers in a composite membrane can be reduced by using the concentration-changing deposition technique. <br /><br /> By selecting appropriate materials and by selecting proper preparation conditions, composite polyelectrolyte membranes with less than 10 self-assembled double layers have been successfully fabricated. The obtained membranes had good performance for the dehydration of IPA/water mixtures by pervaporation. The lowest number of double layers in a composite membrane was 2 and this composite membrane had both a high flux and a high selectivity. It was also found that using polyelectrolytes with high molecular weights and a porous substrate with fine pores were the prerequisites for making composite polyelectrolyte membranes with less than 10 self-assembled double layers, while using a polyelectrolyte pair with high charge densities was the prerequisite for making composite membranes with a high selectivity. The successful fabrication of polyelectrolyte membranes with less than 10 double layers makes self-assembled membranes more practical because self-assembled composite membranes can be easily fabricated. <br /><br /> The data reproducibility and the stability of self-assembled composite membranes with less than 10 double layers have been discussed in this work. Random defects in the self-assembled separating layer and low repeatability of thickness in the first several deposition layers are believed to be the major reasons for the relatively low data reproducibility of single composite membranes, while the conformation change of adsorbed polyelectrolytes is one of the reasons for the flux reduction of composite membranes with less than 10 self-assembled double layers. Though the flux reproducibility of single membranes is barely acceptable (relative error about 25%), the average fluxes of several membranes made under the same conditions show good reproducibility. All composite membranes with less than 10 self-assembled double layers, from a structure point of view, were stable because the fluxes of polyelectrolyte membranes didn?t increase as time passed. <br /><br /> The separation performance of the self-assembled composite membranes developed in this work is not as good as it was originally expected, but it is still better than that of commercial poly(vinyl alcohol) (PVA) membranes for the dehydration of IPA/water mixtures, which indicates that new self-assembled composite membranes could be used for practical dehydration of IPA. The flux of the self-assembled composite membrane with 2 double layers was two times higher than that of reported self-assembled membrane in the literature when an IPA/water feed mixture with 10. 0 wt% of water was used at 60&deg;C. The composite membrane with 2 self-assembled double layers is a high performance membrane for IPA dehydration. <br /><br /> The formation of a single self-assembled layer on a non-porous substrate has been studied, but nothing has been reported about the formation of a self-assembled multilayer on a porous substrate. Based on the separation performance of different self-assembled composite membranes made from different materials and at different fabrication conditions, a two-stage process is proposed to explain the formation of a self-assembled multilayer on a porous substrate. Polyelectrolyte molecules, in the first stage, will deposit on the non-porous portion of the surface of a porous substrate while polyelectrolyte molecules will go into and fill the pores on the surface of a porous substrate to change a porous substrate into a "non-porous" substrate. In the second stage, polyelectrolyte molecules will deposit on a "non-porous substrate" to form a multilayer. This process can also be used to explain the formation of a multilayer on a non-porous substrate.

Electrostatic self-assembly is a simple, yet versatile and environmentally friendly technique. This technique has been widely used in different areas and recently it has also been used to make nano-structured separating layers for composite polyelectrolyte pervaporation membranes. Non-porous substrates are usually employed for electrostatic self-assembly depositions, but porous substrates have to be used for membrane applications because the composite membranes fabricated with non-porous substrates will have low permeation fluxes. When porous substrates were used to make composite membranes for pervaporation, it was reported that 60 double-layers were needed to get a membrane with suitable separation performance. The deposition of each double-layer needed about one hour, and the fabrication of reported self-assembled membranes with porous substrates was time-consuming and, from an industrial point of view, not practical. <br /><br /> The aim of this work was to make self-assembled composite membranes in a more practical way. The methodology used here is to find appropriate materials and suitable preparation conditions to make self-assembled composite membranes that have less than 10 self-assembled double layers but still have good performance for the dehydration of isopropyl alcohol (IPA)/ water mixtures by pervaporation. <br /><br /> A hydrolyzed polyacrylonitrile (PAN) ultrafiltration membrane is a permanently charged porous material. In this work, this porous material was, for the first time, used as a substrate for the fabrication of a composite self-assembled membrane. It was found that the hydrolyzed porous PAN membranes were good substrates for making self-assembled membranes for pervaporation. <br /><br /> In order to reduce the number of the depositions required for making composite membranes with suitable separation performance, a new deposition technique, concentration-changing deposition technique, has been developed. To obtain more extended conformations of polyelectrolytes to prevent them from going into the pores on a porous substrate, dilute deposition solutions were used for the first several depositions. After these first depositions, the pore size of the porous substrate had been reduced and more concentrated solutions (but still dilute solutions) could be used for the subsequent depositions. By using more concentrated deposition solutions, the number of the polyelectrolyte coils adsorbed by the charged substrate was increased and the thickness of each deposited layer was increased. In this way, the total number of deposition layers needed for a good membrane would be decreased. It has been proved in this work that the number of deposition layers in a composite membrane can be reduced by using the concentration-changing deposition technique. <br /><br /> By selecting appropriate materials and by selecting proper preparation conditions, composite polyelectrolyte membranes with less than 10 self-assembled double layers have been successfully fabricated. The obtained membranes had good performance for the dehydration of IPA/water mixtures by pervaporation. The lowest number of double layers in a composite membrane was 2 and this composite membrane had both a high flux and a high selectivity. It was also found that using polyelectrolytes with high molecular weights and a porous substrate with fine pores were the prerequisites for making composite polyelectrolyte membranes with less than 10 self-assembled double layers, while using a polyelectrolyte pair with high charge densities was the prerequisite for making composite membranes with a high selectivity. The successful fabrication of polyelectrolyte membranes with less than 10 double layers makes self-assembled membranes more practical because self-assembled composite membranes can be easily fabricated. <br /><br /> The data reproducibility and the stability of self-assembled composite membranes with less than 10 double layers have been discussed in this work. Random defects in the self-assembled separating layer and low repeatability of thickness in the first several deposition layers are believed to be the major reasons for the relatively low data reproducibility of single composite membranes, while the conformation change of adsorbed polyelectrolytes is one of the reasons for the flux reduction of composite membranes with less than 10 self-assembled double layers. Though the flux reproducibility of single membranes is barely acceptable (relative error about 25%), the average fluxes of several membranes made under the same conditions show good reproducibility. All composite membranes with less than 10 self-assembled double layers, from a structure point of view, were stable because the fluxes of polyelectrolyte membranes didn?t increase as time passed. <br /><br /> The separation performance of the self-assembled composite membranes developed in this work is not as good as it was originally expected, but it is still better than that of commercial poly(vinyl alcohol) (PVA) membranes for the dehydration of IPA/water mixtures, which indicates that new self-assembled composite membranes could be used for practical dehydration of IPA. The flux of the self-assembled composite membrane with 2 double layers was two times higher than that of reported self-assembled membrane in the literature when an IPA/water feed mixture with 10. 0 wt% of water was used at 60&deg;C. The composite membrane with 2 self-assembled double layers is a high performance membrane for IPA dehydration. <br /><br /> The formation of a single self-assembled layer on a non-porous substrate has been studied, but nothing has been reported about the formation of a self-assembled multilayer on a porous substrate. Based on the separation performance of different self-assembled composite membranes made from different materials and at different fabrication conditions, a two-stage process is proposed to explain the formation of a self-assembled multilayer on a porous substrate. Polyelectrolyte molecules, in the first stage, will deposit on the non-porous portion of the surface of a porous substrate while polyelectrolyte molecules will go into and fill the pores on the surface of a porous substrate to change a porous substrate into a "non-porous" substrate. In the second stage, polyelectrolyte molecules will deposit on a "non-porous substrate" to form a multilayer. This process can also be used to explain the formation of a multilayer on a non-porous substrate.

No description available.

Since the 1990s, facing increasing competition and mass customization, many companies including Dell have chosen to adopt the assemble-to-order (ATO) model in order to increase products offering and reduce the life cycles of products. Inventory management is a key challenge for ATO systems, in particular determination of inventory replenishment levels without full demand information, component allocations based on available component inventories, and realizations of product demands. ATO systems are usually modeled as a two-stage stochastic integer program. However, such programs are typically hard to solve, especially for stochastic integer nonlinear programs used for the joint optimization. In this thesis, we describe two ATO models proposed by Ackay and Xu (2004) and by Huang (2014). Both models include a nonlinear term in the right hand side of the inventory availability constraints. We discuss the techniques used to linearize the original problem and to estimate the impact of the linearization. In addition, we investigate another key element of ATO systems called component commonality used to reduce inventory costs. An extensive literature review regarding component commonality is provided. / Thesis / Master of Science (MSc)

<p>The microphase segregation behavior, which exhibits periodic patterns on a mesoscale, has been found in many systems where it has demonstrated its extreme industrial usefulness in the diblock copolymer system. When studying more general isotropic colloidal systems, periodic microphases should ubiquitously emerge in systems for which short-range inter-particle attraction is frustrated by long-range repulsion~(SALR). The morphological richness of these phases makes them desirable material targets, but our relatively coarse understanding of even simple models hinders controlling their assembly both from thermodynamic and dynamic points of view. The thermodynamic question is what should be the appropriate potential to stabilize microphases, such as cluster crystal, cylindrical, double gyroid and lamellar, while the dynamic question is whether the current experiments are long enough for these phases to appear. This dissertation will focus on solving these two parts of problems and hopefully guide the experiments to discover a simple material that can have microphase segregation behavior. In order to answer the thermodynamic problem of the stability of the microphases, we use a novel thermodynamic integration method as well as density functional methods in comparing the free energy of the microphases with uniform liquids. With the thermodynamic integration, we locate FCC-cluster, cylindrical, double gyroid and lamellar phases as well as nontrivial interplay between cluster, gel and microphase formation for a model microphase former. We also extended the methods to the model with a shorter and longer repulsion region where we found that the shorter region of the system may be in the Wigner glass of clusters of different sizes rather than the microphases. We also compare our simulation results with that from the density functional theory where we demonstrate that the classical density functional theory is qualitatively right but the simple improvement of the radial distribution functional by assuming the system is the same as Percus-Yevick hard sphere does not make a quantitatively difference. Our finding confirms that if the colloidal system has proper SALR potential as well as the right regime of area fraction and temperature, the microphase will be found in these systems. We then answer the second question which is whether the slow dynamics hinders the formation of microphases. We study the modeled microphase former and track the change of the first peak in the structure factor as well as the structural correlation time. We found that the system has a very complex dynamical regimes, including homogeneous fluid, void micelle, liquid gel and solid gel. The system becomes extreme slow in the solid gel regime but if in the regime that density and temperature are near the order-disorder transition, the lamellar self-assembly is much faster than the relaxation time of the solid gel which may explain why in the experimental system, the colloids seem stuck forever. We have collaborated with an experimental group to realize the SALR self-assemble behavior in a well controlled system. We have calibrated the system using a high precision thermodynamic integration by determining and matching the critical point and triple point of the experiments when the system is set up in the purely attractive regime. The system, however, becomes unpredictable when it goes into the SALR system where both higher body and other interactions become dominant. Finally, we try to extend our system to a spherocylinder model, which is an anisotropic particles with SALR. We have developed a novel cell list method here to accelerate the simulation. By determining the percolation transition and the order parameter, we find that the simple anisotropic interaction will introduce a much complex phase behavior of the system even in the disordered regime. We have identified several disordered phases, including homogeneous liquid, micellar liquid, free rotator gel, nematic gel and smectic gel.</p> / Dissertation

Amphiphilic polymers are a subset of macromolecules that exhibit both hydrophobic and hydrophilic moieties within their covalently bonded structures. Because of the differing solubilities of the contrasting regions of the amphiphilic polymers, they exhibit an inherent ability to self-assemble in the solution phase where one block exhibits poor compatibility with the solvent. And by tuning the composition, size and shape of the polymers, a variety of morphologies of the assembly in solution were observed, like spherical micelle, vesicle, rod-like and lamellar. The propensity to self-assemble to complex structures makes them promising candidates in wide varieties of applications, for example, drug delivery, gene transfection, catalyst, and sensing. Nowadays, most of the researches of amphiphilic polymers have been focused on simple linear di-block copolymers. Amphiphilic non-linear architectures, like dendrimers, star polymers, hyperbranched polymers, brush polymers and cyclic polymers, have been proved to exhibit unique properties compare to their linear analogs, such as lower critical micelle concentrations and better-assembled strengths because the structures are covalently tethered together. These unique properties make them a particularly attractive vehicle in drug/gene delivery. However, investigations of the amphiphilic homopolymers are limited and the majority of work have been done is focused on charged polymers, anionic or cationic. The amphiphilic ionic homopolymers largely relied on the pH of the solution to assemble into complex morphologies, perturbation of pH could result in deformation of assemblies and pro-release of encapsulate. Also, extremely severe pH environment prohibit the usages of the amphiphilic polymers in biological systems. Well defined non-ionic amphiphilic linear homopolymers bearing hydrophobic decyl groups and hydrophilic tri(ethylene glycol) monomethyl ether groups was synthesized by atom transfer radical polymerization technique and the structures were confirmed by NMR and GPC. The low polyedispersity polymers, were found to readily self-assembled to form micelles in non-polar organic phase and reverse micelles in polar aqueous phase. The assemblies were studied with UV-vis spectroscopy, fluorescence spectroscopy, dynamic light scattering, and transmission electron microscopy to determine the critical micelle concentrations and assembly size in both conditions. The synthesis towards more complex architectures of the homopolymers was also investigated. / acase@tulane.edu

The name of this subject is ‘The investigation of parts orientation efficiency resing search technique’. Problems in parts interdependent orientation when using different movement trajectories in perpendicular to assembly plane are investigated. An influence of search trajectories on joining accuracy is analyzed.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16883号 / 工博第3604号 / 新制||工||1544(附属図書館) / 29558 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 長谷川 博一, 教授 吉﨑 武尚, 教授 金谷 利治 / 学位規則第4条第1項該当

En este proyecto se manifiesta una idea de negocio planteada por un grupo de estudiantes de la UPC. Los conocimientos aprendidos a lo largo de la carrera de cada uno han sido expuestos en el siguiente Trabajo. En primer lugar, hemos identificado el problema donde el usuario se ve en la necesidad de quedarse en casa tras el temor a la inseguridad ciudadana, en donde los altos índices de delincuencia han hecho que las personas opten por permanecer en casa o un lugar privado para pasar un buen momento. Por esta razón, creamos un producto para que las personas disfruten de un momento ameno sin exponerse. Siendo nuestro público objetivo personas de 18 a 60 años de edad de los NSE A - B de las zonas 7 y 8 de la ciudad limeña. Por esta razón, fundamos Tantay, una salsa de ají con finas hierbas 100% natural, elaborada con ingredientes de calidad de procedencia peruana y bajo un proceso artesanal, siendo una opción de acompañamiento para snacks u otros alimentos. Una combinación de sabores y texturas es lo que representa nuestra salsa, gracias a la amplia variedad de insumos nacionales que proporcionarán frescura y naturalidad al producto. Para lograr todo lo mencionado, hemos desarrollado un análisis donde se desarrollará planes estratégicos que abarquen Plan de Marketing, Plan operacional, Plan de Recursos Humanos, Plan de Responsabilidad Social y el Plan Financiero para poder evaluar la empresa y desarrollar el proyecto con éxito. / This project manifests a business idea raised by a group of UPC students. The knowledge learned throughout the career of each one has been exposed in the following Work. Firstly, we have identified the problem where the user sees himself in the need to stay at home after fear of citizen insecurity, where high crime rates have made people choose to stay at home or a private place to have a good time. For this reason, we create a product for people to enjoy a pleasant moment without exposing themselves. Our target audience is people between 18 and 60 years of age from the NSE A - B of zones 7 and 8 of the Lima city. For this reason, we founded Tantay, a chili sauce with fine herbs 100% natural, made with quality ingredients of Peruvian origin and under an artisanal process, being an accompaniment option for snacks or other foods. A combination of flavors and textures is what our sauce represents, thanks to the wide variety of national ingredients that will provide freshness and naturalness to the product. To achieve all of the aforementioned, we have developed an analysis where strategic plans will be developed that include the Marketing Plan, the Operational Plan, the Human Resources Plan, the Social Responsibility Plan and the Financial Plan in order to evaluate the company and carry out the project successfully. / Trabajo de investigación