Adenine as an organocatalyst for the ring-opening polymerization of lactide: scope, mechanism and access to adenine-functionalized polylactide

Nucleobase-functionalized polymers are widely used in the fields of supramolecular chemistry and self-assembly, and their development for biomedical applications is also an area of interest. They are usually synthesized by tedious multistep procedures. In this study, we assess adenine as an organoinitiator/ organocatalyst for the ring-opening polymerization of lactide. L-Lactide can be quantitatively polymerized in the presence of adenine. Reaction conditions involving short reaction times and relatively low temperatures enable the access to adenine end-capped polylactide in a simple one-step procedure, in bulk, without additional catalyst. DFT calculations show that the polymerization occurs via hydrogen bond catalysis. The mechanism involves (i) a hydrogen bond between the NH9 of adenine and the carbonyl moiety of lactide, leading to an electron deficient carbon atom, and (ii) a second hydrogen bond between the N3 of adenine and the NH2 of a second adenine molecule, followed by a nucleophilic attack of the latter activated amine on the former electron deficient carbon on the monomer. For longer reaction times and higher temperatures, macrocyclic species are formed, and a mechanism involving the imidazole ring of adenine is proposed based on literature studies. Depending on the reaction conditions, adenine can thus be considered as an organoinitiator or an organocatalyst for the ring-opening polymerization of lactide.

Adenine as an organocatalyst for the ring-opening polymerization of lactide: scope, mechanism and access to adenine-functionalized polylactide

Nucleobase-functionalized polymers are widely used in the fields of supramolecular chemistry and self-assembly, and their development for biomedical applications is also an area of interest. They are usually synthesized by tedious multistep procedures. In this study, we assess adenine as an organoinitiator/organocatalyst for the ring-opening polymerization of lactide. L-Lactide can be quantitatively polymerized in the presence of adenine. Reaction conditions involving short reaction times and relatively low temperatures enable the access to adenine end-capped polylactide in a simple one-step procedure, in bulk, without additional catalyst. DFT calculations show that the polymerization occurs via hydrogen bond catalysis. The mechanism involves (i) a hydrogen bond between the NH9 of adenine and the carbonyl moiety of lactide, leading to an electron deficient carbon atom, and (ii) a second hydrogen bond between the N3 of adenine and the NH2 of a second adenine molecule, followed by a nucleophilic attack of the latter activated amine on the former electron deficient carbon on the monomer. For longer reaction times and higher temperatures, macrocyclic species are formed, and a mechanism involving the imidazole ring of adenine is proposed based on literature studies. Depending on the reaction conditions, adenine can thus be considered as an organoinitiator or an organocatalyst for the ring-opening polymerization of lactide.

Barreiras e facilitadores à prática do acompanhamento farmacoterapêutico nos serviços farmacêuticos hospitalares portugueses

Objectivos: Identificar e compreender as barreiras e os facilitadores à prática do Acompanhamento Farmacoterapêutico (AFT) nos serviços farmacêuticos hospitalares portugueses. Método: Estudo qualitativo mediante realização de entrevistas semi-estruturadas a farmacêuticos hospitalares com e sem experiência no AFT e análise de conteúdo, retroactiva e temática. Resultados: Estrutura dos serviços farmacêuticos: barreiras (1) falta de tempo, organização das actividades orientadas para a logística, instabilidade dos recursos humanos, barreiras físicas à comunicação, relações em divergência; facilitadores (2) reestruturação, trabalho em equipa. Farmacêutico: (1) resistência à mudança, qualificação inadequada; (2) atitude positiva, legitimação, formação. Meio externo: (1) falta de apoio institucional, relacionamento com o doente, o médico e farmacêutico comunitário, ensino inadequado; (2) apoio institucional, procura do doente, cooperação com o médico e o farmacêutico comunitário, ensino adequado. Tecnologia: (1) acesso aos dados clínicos e a informação, método inadequado; (2) acesso à informação, método adequado, documentação, informatização, marketing, boas práticas. Conclusão: As entrevistas semi-estruturadas fornecerem uma visão ampla, detalhada e pragmática dos potenciais determinantes de uma prática generalizada do AFT nos serviços farmacêuticos hospitalares portugueses. /ABSTRACT: Objectives: To identify and understand the barriers and facilitators for the practice of Medication Therapy Management (MTM) in portuguese’s hospital pharmacy. Method: Qualitative study trough semi-structured interviews with MTM experienced and inexperienced hospital pharmacists followed by retroactive content and thematic analysis. Results: Structure of hospital pharmacy: barriers (1) lack of time, activities focused on logistics, instability of human resources, physical barriers to communication, divergent relationships; facilitators (2) restructuring, teamwork. Pharmacist: (1) resistance to change, inadequate skills, (2) positive attitude, legitimating, formation. Environment: (1) lack of institutional support, relationship with patient, physician and community pharmacist, inadequate teaching, (2) institutional support, patient's demand, cooperation with physician and community pharmacist, appropriate teaching. Technology: (1) lack of access to clinical data and information, inadequate method, (2) access to information, appropriate method, documentation, computerization, marketing, good pharmacy practices. Conclusion: The semi-structured interviews provide a broad, comprehensive and pragmatic view of potential determinants for wide practice of MTM in Portuguese’s hospital pharmacy.

Sistema de referenciação geográfica

Nos dias de hoje o acesso à informação por parte das empresas é vital para o bom desempenho das suas funções. As empresas de telecomunicações não fogem à regra, a sua posição no mercado está dependente das decisões que são tomadas com base na avaliação dessa informação. Para suportar os processos de apoio à decisão é coerente recorrer-se a Data Warehouses que permitem integrar informação de diversas fontes, verificando a sua qualidade, actualização e coerência, organizando-a para um fácil acesso e consulta de vários pontos de vista. Numa empresa de telecomunicações móvel, um Data Mart geográfico baseado na informação de tráfego da companhia que pode identificar as localizações preferenciais dos utilizadores na rede é muito importante porque fornece indicadores muito úteis para o departamento de marketing e negócio da empresa de maneira a que se saiba onde e como actuar para permitir que esta se desenvolva e ganhe vantagem no mercado. ABSTRACT: Today the access to information by enterprises is vital for the company’s performance. Telecommunications companies are no exception. Their position in the market is dependent on the decisions that are taken based on the evaluation of such information. To support the decision making process Data Warehouse is today an extremely useful tool; it integrates information from different sources, checking on its validity, quality and update, coherence, organizing it for an easy access and search from various perspectives. ln a mobile telecommunications company a geographical Data Mart-based traffic information that can identify the preferential locations of users on the network is very important It provides useful indicators to the Department of Marketing and Business there by allowing you to know where and how to act and boosting the development of the company.