RESUMO
The establishment of advanced living/controlled polymerization protocols allows for engineering synthetic polymers in a precise fashion. Combining advanced living/controlled polymerization techniques with highly efficient coupling chemistries facilitates quantitative, modular, and orthogonal functionalization of synthetic polymer strands at their chain termini as well as side-chain functionalization. The review highlights the current status of selected post-functionalization techniques of polymers via orthogonal ligation chemistries, major characteristics of the specific transformation chemistry, as well as the characterization of the products.
Assuntos
Química Orgânica/métodos , Polímeros/química , Catálise , Reação de Cicloadição , Oximas/química , Compostos de Sulfidrila/químicaRESUMO
In light of the increasing demand for ultra rapid and mild conjugation chemistries for use in macromolecular chemistry, the present Feature Article provides a critical overview of the very latest developments in this field. The principal aim, therefore, is the provision of a quick selection guide to aid in the formulation of a design strategy for novel functional materials and to provide recommendations for future developments in the chemistries discussed.
RESUMO
The use of the reversible addition fragmentation chain transfer-hetero Diels-Alder (RAFT-HDA) click reaction for the modular construction of block copolymers is extended to the generation of high molecular weight materials. Cyclopentadienyl end-functionalized polystyrene (PS-Cp) prepared via both atom transfer radical polymerization (ATRP) and the RAFT process are conjugated to poly(isobornyl acrylate) (PiBoA) (also prepared via RAFT polymerization) to achieve well-defined block copolymers with molecular weights ranging from 34 000 to over 100 000 g · mol(-1) and with small polydispersities (PDI < 1.2). The conjugation reactions proceeded in a very rapid fashion (less than 10 min in the majority of cases) under ambient conditions of temperature and atmosphere. The present study demonstrates-for the first time-that RAFT-HDA click chemistry can provide access to high molecular weight block copolymers in a simple and straight-forward fashion.
RESUMO
Block copolymers in seconds: Catalyst-free, ambient-temperature click conjugation of individual polymer strands becomes possible using novel ATRP-derived cyclopentadienyl-capped polymers in an extremely rapid hetero-Diels-Alder cycloaddition with macromolecules equipped with electron-deficient dithioester end groups prepared by the RAFT process.
RESUMO
BACKGROUND: Tricuspid annular plane systolic excursion (TAPSE) is frequently used as an objective measure of right-ventricular dysfunction. Abnormal TAPSE values are associated with poor prognosis in a number of disease states; however, the measure is not always easy to obtain in the critically ill. The purpose of this study is to assess the feasibility and accuracy of using a subcostal view and TAPSE measurement as a measure of right-ventricular dysfunction. A secondary aim was to perform a pilot study to assess whether right-ventricular dysfunction was associated with adverse outcomes including mortality. RESULTS: Subcostal TAPSE corresponds well with TAPSE obtained from the apical window at low and moderate TAPSE values (mean difference 1.2 mm (CI 0.04-2.36; 100% data pairs < 3-mm difference for TAPSE < 19 mm; 92% had < 3 mm difference at TAPDE < 24 mm). Subcostal TAPSE is able to accurately discriminate between abnormal and normal TAPSE results (sensitivity 97.8%, specificity 87.5%). There was no association between right-ventricular (RV) dysfunction and 90-day mortality. CONCLUSIONS: Subcostal TAPSE is a feasible and accurate alternative to conventional TAPSE from the apical view in critically ill patients. Further research is required to elucidate the relationship between RV dysfunction and outcomes in sepsis.
RESUMO
The tendency of electron-deficient dithioesters to undergo hetero Diels-Alder cycloadditions is successfully used to generate polymer conjugates between a RAFT-polymerized poly(styrene) and a diene-terminated poly(epsilon-caprolactone).
RESUMO
OBJECTIVE: To compare lung ultrasonography (LUS), chest xray (CXR) and physical examination (Ex) for the detection of pathological abnormalities in the lungs of critically ill patients. DESIGN, SETTING AND PARTICIPANTS: A prospective cohort study of 145 patients in the intensive care unit of a tertiary teaching hospital who were undergoing echocardiography for a clinical indication. MAIN OUTCOME MEASURES: Each patient was independently assessed by Ex, CXR and LUS on the same day. Examiners were asked to comment on the presence or absence and severity of pleural effusion, lung consolidation and alveolar interstitial syndrome (AIS). Independent expert examiners performed the LUS and an independent radiologist reported on the CXR. RESULTS: Ex, CXR and LUS were in fair agreement with each other in detecting a pulmonary abnormality (CXR v LUS, κ = 0.31; CXR v Ex, κ = 0.29; LUS v Ex, κ = 0.22). LUS detected more abnormalities than did CXR (16.2%; χ(2) = 64.1; P < 0.001) or Ex (23.5%; χ(2) = 121.9; P < 0.001). CXR detected more pleural effusions than LUS (9.3%; χ(2) = 7.6; κ = 0.39), but LUS detected more pleural effusions than Ex (22.8%; χ(2) = 36.4; κ = 0.18). There was no significant difference in the performance of LUS and CXR in quantifying the size of a pleural effusion (Z = -1.2; P = 0.23). Ex underestimated size compared with CXR or LUS. LUS detected more consolidation than CXR (17%; χ(2) = 115.9; P < 0.001) and Ex (16.2%; χ(2) = 90.3; P < 0.001). We saw no difference in performance between CXR and Ex in detecting lung consolidation (0.9%; χ(2) = 0.51; P < 0.48). LUS detected more cases of AIS than CXR (5.5%; χ(2) = 7.9; P = 0.005) and Ex (13%; χ(2) = 25.8; P < 0.001). CONCLUSIONS: There was only fair-to-moderate agreement between LUS, CXR and Ex in detecting pulmonary abnormalities, including pleural effusion, lung consolidation and AIS. The higher rate of detection from LUS, combined with its ease of use and increasing accessibility, makes for a powerful diagnostic tool in the ICU.