Surface structure of thin asymmetric PS-b-PMMA diblock copolymers investigated by atomic force microscopy

Asymmetric poly(styrene-b-methyl methacrylate) (PS-b-PMMA) diblock copolymers of molecular weight M-n = 29,700g mol(-1) (M-PS = 9300 g mol(-1) M-PMMA = 20,100 g mol(-1), PD = 1.15, chi(PS) = 0.323, chi(PMMA) = 0.677) and M-n = 63,900 g mol(-1) (M-PS = 50,500 g mol(-1), M-PMMA = 13,400 g mol(-1), PD = 1.18, chi(PS) = 0.790, chi(PMMA) = 0.210) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Atomic force microscopy (AFM) was used to investigate the surface structure of thin films, prepared by spin-coating the diblock copolymers on a silicon substrate. We show that the nanostructure of the diblock copolymer depends on the molecular weight and volume fraction of the diblock copolymers. We observed a perpendicular lamellar structure for the high molar mass sample and a hexagonal-packed cylindrical patterning for the lower molar mass one. Small-angle X-ray scattering investigation of these samples without annealing did not reveal any ordered structure. Annealing of PS-b-PMMA samples at 160 degrees C for 24 h led to a change in surface structure

Extreme reversed sexual dichromatism in a bird without sex role reversal

Brilliant plumage is typical of male birds, reflecting differential enhancement of male traits when females are the limiting sex. Brighter females are thought to evolve exclusively in response to sex role reversal. The striking reversed plumage dichromatism of Eclectus roratus parrots does not fit this pattern. We quantify plumage color in this species and show that very different selection pressures are acting on males and females. Male plumage reflects a compromise between the conflicting requirements for camouflage from predators while foraging and conspicuousness during display. Females are liberated from the need for camouflage but compete for rare nest hollows

The automated array assembly task of the low-cost silicon solar array project, phase 2

Several specific processing steps as part of a total process sequence for manufacturing silicon solar cells were studied. Ion implantation was identified as the preferred process step for impurity doping. Unanalyzed beam ion implantation was shown to have major cost advantages over analyzed beam implantation. Further, high quality cells were fabricated using a high current unanalyzed beam. Mechanically masked plasma patterning of silicon nitride was shown to be capable of forming fine lines on silicon surfaces with spacings between mask and substrate as great as 250 micrometers. Extensive work was performed on advances in plated metallization. The need for the thick electroless palladium layer was eliminated. Further, copper was successfully utilized as a conductor layer utilizing nickel as a barrier to copper diffusion into the silicon. Plasma etching of silicon for texturing and saw damage removal was shown technically feasible but not cost effective compared to wet chemical etching techniques

Processing experiments on non-Czochralski silicon sheet

A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation

Laser-zone Growth in a Ribbon-to-ribbon (RTR) Process Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Solar Array Project

A technique for growing limited-length ribbons continually was demonstrated. This Rigid Edge technique can be used to recrystallize about 95% of the polyribbon feedstock. A major advantage of this method is that only a single, constant length silicon ribbon is handled throughout the entire process sequence; this may be accomplished using cassettes similar to those presently in use for processing Czochralski waters. Thus a transition from Cz to ribbon technology can be smoothly affected. The maximum size being considered, 3 inches x 24 inches, is half a square foot, and will generate 6 watts for 12% efficiency at 1 sun. Silicon dioxide has been demonstrated as an effective, practical diffusion barrier for use during the polyribbon formation

Measurements of total alkalinity and inorganic dissolved carbon in the Atlantic Ocean and adjacent Southern Ocean between 2008 and 2010

Water column dissolved inorganic carbon and total alkalinity were measured during five hydrographic sections in the Atlantic Ocean and Drake Passage. The work was funded through the Strategic Funding Initiative of the UK's Oceans2025 programme, which ran from 2007 to 2012. The aims of this programme were to establish the regional budgets of natural and anthropogenic carbon in the North Atlantic, the South Atlantic, and the Atlantic sector of the Southern Ocean, as well as the rates of change of these budgets. This paper describes in detail the dissolved inorganic carbon and total alkalinity data collected along east–west sections at 47° N to 60° N, 24.5° N, and 24° S in the Atlantic and across two Drake Passage sections. Other hydrographic and biogeochemical parameters were measured during these sections, and relevant standard operating procedures are mentioned here. Over 95% of dissolved inorganic carbon and total alkalinity samples taken during the 24.5° N, 24° S, and the Drake Passage sections were analysed onboard and subjected to a first-level quality control addressing technical and analytical issues. Samples taken along 47° N to 60° N were analysed and subjected to quality control back in the laboratory. Complete post-cruise second-level quality control was performed using cross-over analysis with historical data in the vicinity of measurements, and data were submitted to the CLIVAR and Carbon Hydrographic Data Office (CCHDO), the Carbon Dioxide Information Analysis Center (CDIAC) and and will be included in the Global Ocean Data Analyses Project, version 2 (GLODAP 2), the upcoming update of Key et al. (2004)

Perceptions of Preparedness Among New Graduate Nurses: Traditional Curriculum Versus Concept-Based Curriculum

Concept-based curriculum (CBC) is a newer trend in nursing education curriculum aimed at preparing new graduates to enter the workforce as generalist nurses better suited to care for a more medically complex population. Using CBC, students are introduced to concepts in order to build conceptual understandings as they engage in knowledge and skill learning, as opposed to a traditional nursing curriculum that is taught in sections grouped by patient population and medical complexity. At a nursing school housed within a private university in the southeast, the traditional nursing curriculum was replaced with CBC in 2016. To better understand the preparedness of new graduate nurses, students graduating from both traditional curriculum and CBC curricular designs were asked about their perception of preparedness in five specific areas during their first three months of clinical practice. The results of the explanatory mixed-methods survey, which consisted of Likert scale responses and qualitative data, showed no statistically significant difference in perception of preparedness between the two groups. The outcomes of each individual curricula were not dramatically different, but the actionable data reinforces the importance of clinical learning

The effect of fear of pain on rehabilitation of acute musculoskeletal injury

The Fear-Avoidance Model (FAM) is a psychological theory that was created to explain why some patients develop chronic back pain while others do not. However, there is little research on the influence of the FAM and acute extremity injuries. Therefore, the aim of our study was to determine if the FAM is correlated to time to return to play from an acute injury. Twenty six student athletes who had suffered an acute injury that required up to six weeks of rehabilitation volunteered for this study. The FAM, including fear of pain (FPQ-III), kinesiphobia (TSK), fear avoidance (FABQ), and catastrophizing (PCS) was assessed using self-report questionnaires. Physical measures recorded included range of motion (ROM), strength, pain, disability, and evoked tenderness. All measurements were taken within 24 hours of an athlete being injured and every two weeks until the athlete returned to play. Return to play (RTP) was defined as returning to competition or practice in days. No significant correlations were discovered between RTP and the FABQ and the TSK. Moderate correlations were found between the medical pain subscale of the FPQ-III and the magnification subscale of the PCS and RTP -0.372 ( p = 0.061) and 0.370 (p = 0.063) respectively. The FABQ was significantly correlated with many of the physical measures, including disability, pain, and ROM. Although we could not confirm the ability of the FAM to predict the length of rehabilitation following an acute injury, moderate trends were found signifying that the FAM provides an important indicator of physical signs