A Micro-manipulation Technique for the Purification of Diatoms for Isotope and Geochemical Analysis

A method is described for the purification and extraction of diatom samples for isotope and geochemical analysis. The technique involves a micro-manipulator attached to an inverted microscope with a cellular micro-injector system used to remove contaminants or separate assemblages into single-species samples. Whilst time consuming, the advances associated with this technique, eliminating issues related to contamination and the impact of species-dependent fractionation factor/isotopic effect, allows ultra-clean as well as species and/or size specific diatom samples to be analysed in palaeoenvironmental research down to seasonal timescale resolution. By further altering the inner dimensions of the commercially available capillary tubes, (3.5–150  $\upmu $ m) this technique can be extended for use with other microfossils including radiolaria (30  $\upmu $ m to 1 mm), pollen (6–100  $\upmu $ m) and phytolith samples (1–200  $\upmu $ m).     

Challenges in nucleic acid‐lipid films for transfection

The use of surface‐based methods for the delivery of therapeutics has recently generated increasing interest. These platforms have tremendous potential to minimize detrimental side effects associated with systemic delivery by localizing the therapeutic vehicle, and thus provide higher local doses for improved efficacy. Cationic lipids are one of the most commonly used synthetic carriers for the delivery of genetic cargo, such as DNA and RNA. However, reports on the use of lipid‐based films for gene delivery are scarce. Here we investigate the use of a lipid‐based film for the in vitro delivery of plasmid DNA. Solid DNA‐lipid films show very low levels of transfection, while identical complexes prepared for bolus delivery provide high levels of transfection when used directly. We investigate the mechanism, whereby the activity of these solid‐state films is lost and suggest methods for circumventing these challenges and restoring the efficacy of these films as gene delivery platforms. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3203–3213, 2013     

Modelling of penetration of horizontal supersonic nozzles in high temperature fluidised beds

Supersonic nozzles have been applied in various jet‐induced fluidised bed attrition processes such as jet milling and Fluid Coking. In jet‐induced particle attrition, the penetration length into the bed of the jet issuing from the supersonic nozzle is a critical property that affects the attrition mechanisms. A numerical model was developed to predict the penetration length of jets issuing from a horizontal supersonic nozzle in high temperature fluidised beds, based on an Eulerian–Eulerian multiphase model and Granular kinetic theory. The predicted jet penetration lengths are in very good agreement with the experimental data and the predictions of Li's empirical correlation [Li, “Penetration of High Velocity Horizontal Gas Jets Into a Fluidized Bed at High Temperature”, in Fluidization XIII, S. D. Kim, Y. Kang, J. K. Lee, Y. C. Seo, Eds., Gyeong‐ju, Korea 2010 ; Engineering Conferences International, Gyeong‐ju, Korea 2010 , pp. 893–900.]. The simulation results have also demonstrated that the fluidisation velocity and bed temperature have little influence on jet penetration length. © 2013 Canadian Society for Chemical Engineering     

New Method of Measuring Permanent Viscosity Loss of Polymer-Containing Lubricants

An ultrahigh shear rate viscometer (USV) was used to measure the viscosity of polymer solutions. It was found that some polymer solutions in base oil, including those used as engine oil viscosity modifiers, show permanent viscosity loss when subjected to very high shear rates above 10⁶ s^?1. The USV was modified to automatically carry out a series of viscosity measurements on the same test lubricant sample. This enabled the accumulation of permanent viscosity loss to be measured over successive strain cycles.

As expected, permanent viscosity loss increased with both strain rate and molecular weight. When carried out at 5 × 10⁶ s^?1 and 100°C, the test was more severe than the Kurt Orbahn test because samples of lubricants subjected to the latter underwent further shear thinning in the USV.

The USV test appears to be a rapid and convenient way to quantify the permanent viscosity loss of polymer-containing lubricants for engine use, and a protocol to assess permanent viscosity loss (PVL) and permanent shear stability index (PSSI) based on viscosity measurements at 10⁶ s^?1 before and after shear thinning is outlined.

The study also shows that it is important to take into account possible permanent viscosity loss when measuring the viscosity of polymer solutions in very high shear rate viscometers such as the USV. This can be done by minimizing the amount of shear to which the lubricant is subjected or by taking successive measurements and subtracting the permanent viscosity loss taking place in each of the first few strain rate cycles.     

Lipids in infant formulas: Current and future innovations

Lipids in infant formulas are designed to mimic the composition of human milk and/or approximate the performance of the breastfed infant. Human milk lipids exhibit a complex, highly variable nature, varying by population, dietary intake, time of day, length of feeding and others. Continued understanding and characterization of human milk lipids has led to infant formula innovations aimed at a better comparison to human milk and/or improved dietary lipid utilization in the formula‐fed infant. The underlying aim of such innovation is the generation of outcomes as comparable to human milk feeding as possible. The present paper briefly reviews the current understanding of human milk lipid composition, with a focus on how this knowledge drives current and future innovations in the area of infant formula lipids.     

Alcohol use by undergraduate students on their 21st birthday: Predictors of actual consumption, anticipated consumption, and normative beliefs.

Recent research has identified celebration of a 21st birthday as an environmental event during which many college students engage in risky levels of alcohol consumption. The current study examined the relationship between personality and different aspects of alcohol use during 21st birthday celebrations: actual amount consumed for those who had turned 21, anticipated amount consumed for those under the age of 21, and normative beliefs regarding the amount other students consume on their 21st birthdays. Sensation seeking and impulsivity both displayed significant bivariate relationships with all three aspects of 21st birthday drinking. Personality traits did not contribute unique variance to actual 21st birthday drinking after the effects of typical alcohol consumption were accounted for in the models. Impulsivity contributed unique variance to models accounting for anticipated drinking and normative beliefs. Additional research is necessary to better understand the role personality variables play on alcohol consumption during 21st birthday celebrations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are adolescents less mature than adults?: Minors' access to abortion, the juvenile death penalty, and the alleged APA "flip-flop."

The American Psychological Association’s (APA’s) stance on the psychological maturity of adolescents has been criticized as inconsistent. In its Supreme Court amicus brief in Roper v. Simmons (2005), which abolished the juvenile death penalty, APA described adolescents as developmentally immature. In its amicus brief in Hodgson v. Minnesota (1990), however, which upheld adolescents’ right to seek an abortion without parental involvement, APA argued that adolescents are as mature as adults. The authors present evidence that adolescents demonstrate adult levels of cognitive capability earlier than they evince emotional and social maturity. On the basis of this research, the authors argue that it is entirely reasonable to assert that adolescents possess the necessary skills to make an informed choice about terminating a pregnancy but are nevertheless less mature than adults in ways that mitigate criminal responsibility. The notion that a single line can be drawn between adolescence and adulthood for different purposes under the law is at odds with developmental science. Drawing age boundaries on the basis of developmental research cannot be done sensibly without a careful and nuanced consideration of the particular demands placed on the individual for “adult-like” maturity in different domains of functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimization of the performance of polymer electrolyte fuel cell membrane-electrode assemblies: Roles of curing parameters on the catalyst and ionomer structures and morphology

In order to understand the origin of performance variations in polymer electrolyte membrane fuel cells (PEMFCs), a series of membrane-electrode assemblies (MEAs) with identical electrode layer compositions were prepared using different electrode curing conditions, their performances were evaluated, and their morphologies determined by scanning electron microscopy (SEM). The polarization curves varied markedly primarily due to differences in morphologies of electrodes, which were dictated by the curing processes. The highest performing MEAs (1.46 W cm⁻² peak power density at 3.2 A cm⁻² and 80 °C) were prepared using a slow curing process at a lower temperature, whereas those MEAs prepared using a faster curing process performed poorly (0.1948 W cm⁻² peak power density at 440 mA cm⁻² and 80 °C). The slowly cured MEAs showed uniform electrode catalyst and ionomer distributions, as revealed in SEM images and elemental maps. The relatively faster cured materials exhibited uneven distribution of ionomer with significant catalyst clustering. Collectively, these results indicate that to achieve optimal performance, factors that affect the dynamics of the curing process, such as rate of solvent evaporation, must be carefully controlled to avoid solvent trapping, minimize catalyst coagulation, and promote even distribution of ionomer.     

Intrinsic stress effect on fracture toughness of plasma enhanced chemical vapor deposited SiNx:H films

The apparent fracture toughness for a series of plasma enhanced chemical vapor deposition SiN_x:H films with intrinsic film stress ranging from 300 MPa tensile to 1 GPa compressive was measured using nanoindentation. The nanoindentation results show the measured fracture toughness for these films can vary from as high as > 8 MPa⋅√m for films in compression to as low as < 0.5 MPa⋅√m for the films in tension. Other film properties such as density, Young's modulus, and hydrogen content were also measured and not observed to correlate as strongly with the measured fracture toughness values. Various theoretical corrections proposed to account for the presence of intrinsic or residual stresses in nanoindent fracture toughness measurements were evaluated and found to severely underestimate the impact of intrinsic stresses at thicknesses ≤ 3 μm. However, regression analysis indicated a simple linear correlation between the apparent fracture toughness and intrinsic film stress. Based on this linear trend, a stress free/intrinsic fracture toughness of 1.8 ± 0.7 MPa⋅√m was determined for the SiN_x:H films.     

Coping with stress during childhood and adolescence: Problems, progress, and potential in theory and research.

Progress and issues in the study of coping with stress during childhood and adolescence are reviewed. Definitions of coping are considered, and the relationship between coping and other aspects of responses to stress (e.g., temperament and stress reactivity) is described. Questionnaire, interview, and observation measures of child and adolescent coping are evaluated with regard to reliability and validity. Studies of the association of coping with symptoms of psychopathology and social and academic competence are reviewed. Initial progress has been made in the conceptualization and measurement of coping, and substantial evidence has accumulated on the association between coping and adjustment. Problems still remain in the conceptualization and measurement of coping in young people, however, and aspects of the development and correlates of coping remain to be identified. An agenda for future research on child–adolescent coping is outlined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)