136 research outputs found

    CO2 hydrogenation to methanol over heterogeneous catalysts:copper and beyond

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    Wall Panel Optimization for Refugee Shelters in Germany: An AHP Study

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    The German government is experiencing difficulties housing and assimilating Syrian refugees in its borders. Erecting temporary shelters on location is one way to deal with the current crises. This thesis attempts to use Analytic Hierarchy Process (AHP) to determine the optimum combination of materials and construction methods to be used in the shelter’s walls in order to improve the living conditions of the refugees and to ensure that the cost is acceptable to the German government. This thesis compares six existing wall panel products from China, which have the lowest cost on the worldwide market. The R-value, strength, price, weight, durability, ease of assembly, assembly time, maintenance costs, comfort, resale value, and appearance were evaluated. Assumptions were made on what the German government would require and on standard building practices in Europe and America. The analysis indicates that the steel frame house from YONGYANG Steel best satisfies the needs in this situation. This thesis produced an AHP template, which is flexible. This model that was developed for the German scenario can be effectively applied to differing emergent situations in other parts of the world

    CO2 hydrogenation to methanol over heterogeneous catalysts:copper and beyond

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    Functionalized layered double hydroxide nanoparticles as an intelligent nanoplatform for synergistic photothermal therapy and chemotherapy of tumors

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    In this work, a novel layered double hydroxide (LDH)-based multifunctional nanoplatform was built for synergistic temperature photothermal therapy (PTT)/chemotherapy. The platform was modified using the peptide B3int to target cancer cells with overexpression of integrin αvβ3. Indocyanine green (ICG) and doxorubicin (DOX) were loaded into the nanocarrier (LDH-PEG-B3int NPs) to form a system having a high DOX drug loading (18.62%) and a remarkable photothermal conversion efficiency of 25.38%. It also showed pH-responsive and near-infrared (NIR)-triggered DOX release. In vitro and in vivo studies indicated that the anti-tumor activity of the combined delivery system was significantly higher than that of a single delivery system. This co-delivery nanosystem may be helpful for future application in the clinical treatment of cancer

    Study on Fracture Initiation and Propagation in a Brazilian Disc with a Preexisting Crack by Digital Image Correlation Method

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    The effect of a preexisting crack with different inclination angles and lengths on mechanical properties, fracture initiation, and propagation in a Brazilian disc was investigated in this paper. In the experiment, digital image correlation (DIC) method was employed to record the deformation in the specimen. Different failure patterns, depending on inclination angles and lengths of the preexisting crack, were observed. The fracture initiation position deviates from the tips of the preexisting crack with the inclination angle increasing from 0° to 72° at an interval of 18° per increment. Secondary cracks are more likely to occur in the Brazilian disc with a more inclined and longer preexisting crack. A finite-discrete element combined method ELFEN was used in the numerical investigation to simulate the failure process. This investigation shows that there are good correlations between the experimental and numerical results. Digital image correlation is a good method to obtain the quantitive full-field strain distribution and to observe the strain evolution process in a jointed rock

    Disagreement and fragmentation in growing groups

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    The arise of disagreement is an emergent phenomenon that can be observed within a growing social group and, beyond a certain threshold, can lead to group fragmentation. To better understand how disagreement emerges, we introduce an analytically tractable model of group formation where individuals have multidimensional binary opinions and the group grows through a noisy homophily principle, i.e., like-minded individuals attract each other with exceptions occurring with some small probability. Assuming that the level of disagreement is correlated with the number of different opinions coexisting within the group, we find analytically and numerically that in growing groups disagreement emerges spontaneously regardless of how small the noise in the system is. Moreover, for groups of infinite size, fragmentation is inevitable. We also show that the model outcomes are robust under different group growth mechanisms.Comment: 17 pages, 3 figure

    Catalytic Depolymerization of Lignin and Woody Biomass in Supercritical Ethanol:Influence of Reaction Temperature and Feedstock

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    The one-step ethanolysis approach to upgrade lignin to monomeric aromatics using a CuMgAl mixed oxide catalyst is studied in detail. The influence of reaction temperature (200-420 °C) on the product distribution is investigated. At low temperature (200-250 °C), recondensation is dominant, while char-forming reactions become significant at high reaction temperature (&gt;380 °C). At preferred intermediate temperatures (300-340 °C), char-forming reactions are effectively suppressed by alkylation and Guerbet and esterification reactions. This shifts the reaction toward depolymerization, explaining high monomeric aromatics yield. Carbon-14 dating analysis of the lignin residue revealed that a substantial amount of the carbon in the lignin residue originates from reactions of lignin with ethanol. Recycling tests show that the activity of the regenerated catalyst was strongly decreased due to a loss of basic sites due to hydrolysis of the MgO function and a loss of surface area due to spinel oxide formation of the Cu and Al components. The utility of this one-step approach for upgrading woody biomass was also demonstrated. An important observation is that conversion of the native lignin contained in the lignocellulosic matrix is much easier than the conversion of technical lignin.</p
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