Development of mixed metal metal-organic polyhedra networks, colloids, and MOFs and their pharmacokinetic applications

The coordination networking of discrete metal-organic polyhedra (MOPs) involving different ligands as well as metals is a challenging task due to the features of limited solubility and chemical stability of these polyhedra. An unusual approach, ligand-oriented polyhedral networking via click chemistry and further metal coordination is reported here. An alkyne decorated Cu(II)-MOP self-catalyzes the regioselective click reaction (1,3-dipolar cycloaddition) using azide-functionalized ligands under unconventional reaction conditions. Introducing new metal ions, M(II), interlinks the carboxylic groups on the MOP surfaces creating coordination networks. On the other hand, exposure of the respective individual ligand components in the presence of Cu(II) promotes an in-situ click reaction along with metal coordination generating a new 3D-framework. These materials demonstrated a high drug hosting potential exhibiting a controlled progressive release of anticancer (5-flourouracil) and stimulant (caffeine) drugs in physiological saline at 37 degrees C. These innovative and unconventional MOP networks provide a significant conceptual advance in understanding

Synthesis of 2D MOF having potential for efficient dye adsorption and catalytic applications

Synthesis of 2D MOFs is often sensitive to the reaction conditions like temperature and solvent etc. Cu(ii)-5-azidoisophthalate MOF (Cu(ii)-5N(3)IP) has been synthesized at room temperature as well as under solvothermal conditions. The azide functional group remained stable during solvothermal synthesis at 85 degrees C. Cu(ii)-5N(3)IP crystallized in a Kagome-type structure. Typical Cu-2 paddle-wheels are connected to each other by 5N(3)IP ligands in infinite 2D sheets in the (001) plane, featuring 1D infinite channels within each layer. This MOF is used for the adsorption of methylene blue (MB), rhodamine B (RhB), methyl orange (MO), and Congo red (CR). The adsorption is selective to the dimensions, shapes and ionic strengths of the dyes. Cu(ii)-5N(3)IP exhibited adsorption rates in the order MB > CR > RhB > MO. Cu(ii)-5N(3)IP is used as a catalyst for aerobic oxidation and Knoevenagel condensation. 3-10 mol% of Cu-5N(3)IP selectively catalyzes the oxidation of benzyl alcohol to benzaldehyde in 9-20 h at 60 degrees C. In Knoevenagel condensation, the reaction of both unsubstituted and substituted benzaldehydes at room temperature was observed at a very low catalyst loading of 3 mol% of MOF within a short time of 3-60 min. This 2D MOF has proved to be more efficient for dye adsorption and the catalytic applications under investigation (such as alcohol oxidation and Knoevenagel condensation) than its analogous 3D or 0D materials

A Identidade do Ensino Superior: a Educação Superior e a Universidade

A definição de uma ‘ideia' de educação superior parece ser uma tarefa que alguns pós-modernistas lançam definitivamente para o caixote do lixo da história. Produto, por excelência, da modernidade, e no cruzamento dos modelos humboldtiano, napoleónico e de Oxbridge, a educação superior, tal como a herdámos, era centrada no conhecimento, isto é, na sua produção (investigação), na sua distribuição (ensino) e na sua difusão pelo corpo social (função de serviço à sociedade). O conhecimento e o seu manuseamento definiam não só a missão institucional como a natureza das organizações consagradas ao ensino superior. A estes elementos componentes da ‘ideia' de educação superior foram incorporados outros igualmente estruturantes: a funcionalidade destas instituições em relação à consolidação e desenvolvimento do Estado-nação. Os quadros necessários ao funcionamento e estrutura do aparelho de Estado encontravam nas universidades e noutros institutos de ensino superior o lugar privilegiado para a sua formação. O que este artigo pretende argumentar é que, num contexto em que a produção, a distribuição e a difusão do conhecimento se transformam, em que a globalização/localização intensifica - sobretudo na Europa - a fragilidade das instâncias nacionais e em que o processo de massificação e de democratização do acesso ao ensino superior o conduzem a outro modelo sociológico que não o de origem, a educação superior está a viver uma identidade esquizóide: educação terciária, pós-secundária, educação fundada na investigação, educação vocacional, etc. Esta situação requer um esforço de reflexividade que, ao mesmo tempo que recusa a procura essencialista de uma ‘ideia' de ensino superior, enfatiza a necessidade de promover uma perspectiva de educação que não soçobre ao pobre paradigma da adaptabilidade, segundo o qual o critério de utilidade de uma dada instituição é directamente proporcional à sua capacidade de sobreviver às mudanças operadas no seu ambiente organizacional.Palavras-chave: Ensino Superior; modernidade; identidade

studyoftheshearratedependenceofgranularfrictionbasedoncommunitydetection

In this study, computer simulations are performed on three-dimensional granular systems under shear conditions. The system comprises granular particles that are confined between two rigid plates. The top plate is subjected to a normal force and driven by a shearing velocity. A positive shear-rate dependence of granular friction, known as velocity-strengthening, exists between the granular and shearing plate. To understand the origin of the dependence of frictional sliding, we treat the granular system as a complex network, where granular particles are nodes and normal contact forces are weighted edges used to obtain insight into the interiors of granular matter. Community structures within granular property networks are detected under different shearing velocities in the steady state. Community parameters, such as the size of the largest cluster and average size of clusters, show significant monotonous trends in shearing velocity associated with the shear-rate dependence of granular friction. Then, we apply an instantaneous change in shearing velocity. A dramatic increase in friction is observed with a change in shearing velocity in the non-steady state. The community structures in the non-steady state are different from those in the steady state. Results indicate that the largest cluster is a key factor affecting the friction between the granular and shearing plate

Mesocrystalline Zn-Doped Fe₃O₄ Hollow Submicrospheres: Formation Mechanism and Enhanced Photo-Fenton Catalytic Performance

Uniform and magnetic recyclable mesocrystalline Zn-doped Fe₃O₄ hollow submicrospheres (HSMSs) were successfully synthesized via a simple one-pot solvothermal route and were used for efficient heterogeneous photo-Fenton catalyst. XRD, XPS, Raman spectroscopy, Mössbauer spectroscopy, SEM, HRTEM, and EDX analyses revealed that the shell of HSMSs is highly porous and assembled by oriented attachment of magnetite nanocrystal building blocks with Zn-rich surfaces. Furthermore, a possible formation mechanism of mesocrystalline hollow materials was proposed. First, Fe₃O₄ mesocrystals were assembled by oriented nanocrystals, and a Zn-rich amorphous shell grew on the surfaces. Then, Zn gradually diffused into Fe₃O₄ crystals to form Zn-doped Fe₃O₄ due to the Kirkendall effect with increasing the reaction time. Meanwhile, the inner nanocrystals would be dissolved, and outer particles would grow larger owing to the Ostwald ripening process, leading to the formation of a hollow structure with porous shell. The Zn-doped Fe₃O₄ HSMSs exhibited high and stable photo-Fenton activity for degradation of rhodamine B (RhB) and cephalexin under visible-light irradiation in the presence of H₂O₂, which results from their hollow mesocrystal structure and Zn doping. It could be easily separated and reused by an external magnetic field. The results suggested that the as-obtained magnetite hollow mesocrystals could be a promising catalyst in the photo-Fenton process