Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles

A hexagonal array of optically active ZnO nanoparticles was synthesized in situ on the solid substrate by utilizing a single-layered film of diblock copolymer micelles as a nanostructured template.X1135sciescopu

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Phase diagrams for the blends of a styrene-butadiene diblock copolymer and a styrene-butadiene random copolymer: Theory

The phase diagram of the blends of a diblock copolymer (A-B) and a random copolymer (ABR) is constructed by the modified confined-chain model developed earlier where the morphology of A-B block copolymer is lamellae and the composition of ABR random copolymer is close to that of A-B. These theoretical results predict a relatively simple phase behavior for the A-B/ABR blends in comparison to the A-B/A blends, A being a homopolymer, studied previously. Unlike in A-B/A blends, the order-disorder transition temperature in A-B/ABR blends is lowered by the addition of the random copolymer regardless of its molecular weight. It is also found that the fraction of ABR solubilized into the A-B is very limited due to the endothermic mixing interaction between ABR and each block of A-B.X115sciescopu

PHASE-DIAGRAMS FOR BLOCK COPOLYMER HOMOPOLYMER BLENDS

A method is proposed for predicting the phase behaviors of blends of homopolymer A with block copolymer A-B. We assume that the mixtures are divided into two distinct states depending on their concentration and temperature. One state is a mesophase having ordered microdomains of the block copolymer, while the other is a liquid phase which consists of the disordered block copolymer and the homopolymer. On the assumption that the block copolymer in the liquid phase acts as a random copolymer, the free energy of mixing for the phase is evaluated by simply applying the Flory-Huggins equation to it. The free energy of mixing for the mesophase can be estimated by modifying the confined chain model originated by Meier. Then the relative stabilities of the two states, the mesophase and the liquid phase, are compared at various temperatures in order to construct a phase diagram. Consequently, by this method, we can obtain the composition-temperature phase diagrams for A/A-B blends, which are consistent with the results of previous experimental investigations.X1119sciescopu

Structure of shear-induced perforated layer phase in styrene-isoprene diblock copolymer melts

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Mechanism of morphological transition from lamellar/perforated layer to gyroid phases

We investigated epitaxial relations of phase transitions between the lamellar (L), hexagonally perforated layers (HPL), and gyroid (G) morphologies in styrene-isoprene diblock copolymer (PSI) and polyisoprene (PI)/PSI blend using rheology and small angle X-ray scattering (SAXS) techniques. In HPL --> G transitions, six spot patterns of G phase were observed in two-dimensitional SAXS pattern. On the ocher hand, in direct L --> G transition without appearance of HPL phase, the polydomain patterns of G phase were observed. From present study, it was understood that direct L-G transition of blend may be suppressed by high-energy barrier of transition and mismatches in domain orientation between epitaxially related lattice planes.X1116sciescopuskc