Children's early ability to solve perspective-taking problems.

Piaget and B. Inhelder (1967 [1948]) claimed that, until 9 or 10 yrs of age, children had great difficulty with perspective taking. J. Huttenlocher and C. C. Presson (1979) showed, however, that these problems were linked to conflict between actual and imagined frames of reference; asking what object occupied a specified location with respect to a hypothetical observer (item questions) led to much better performance. The present experiments extend these findings to younger children: 5-yr-olds (Exp 1); 4-yr-olds, for near and far locations but not left and right (Exp 2); 4-yr-olds for left–right questions (Exp 3); and 3-yr-olds (Exp 4). In addition, Exp 4 showed that memory was not the basis for answering. These data show clearly that preschool children can indicate locations relative to another position. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cleavable Crosslinkers as Tissue Fixation Reagents for Proteomic Analysis

Formaldehyde fixation is widely used for long‐term maintenance of tissue. However, due to formaldehyde‐induced crosslinks, fixed tissue proteins are difficult to extract, which hampers mass spectrometry (MS) proteomic analyses. Recent years have seen the use of different combinations of high temperature and solubilizing agents (usually derived from antigen retrieval techniques) to unravel formaldehyde‐fixed paraffin‐embedded tissue proteomes. However, to achieve protein extraction yields similar to those of fresh‐frozen tissue, high‐temperature heating is necessary. Such harsh extraction conditions can affect sensitive amino acids and post‐translational modifications, resulting in the loss of important information, while still not resulting in protein yields comparable to those of fresh‐frozen tissue. Herein, the objective is to evaluate cleavable protein crosslinkers as fixatives that allow tissue preservation and efficient protein extraction from fixed tissue for MS proteomics under mild conditions. With this goal in mind, disuccinimidyl tartrate (DST) and dithiobis(succinimidylpropionate) (DSP) are investigated as cleavable fixating reagents. These compounds crosslink proteins by reacting with amino groups, leading to amide bond formation, and can be cleaved with sodium metaperiodate (cis‐diols, DST) or reducing agents (disulfide bonds, DSP), respectively. Results show that cleavable protein crosslinking with DST and DSP allows tissue fixation with morphology preservation comparable to that of formaldehyde. In addition, cleavage of DSP improves protein recovery from fixed tissue by a factor of 18 and increases the number of identified proteins by approximately 20 % under mild extraction conditions compared with those of formaldehyde‐fixed paraffin‐embedded tissue. A major advantage of DSP is the introduction of well‐defined protein modifications that can be taken into account during database searching. In contrast to DSP fixation, DST fixation followed by cleavage with sodium metaperiodate, although effective, results in side reactions that prevent effective protein extraction and interfere with protein identification. Protein crosslinkers that can be cleaved under mild conditions and result in defined modifications, such as DSP, are thus viable alternatives to formaldehyde as tissue fixatives to facilitate protein analysis from paraffin‐embedded, fixed tissue.     

Determinants of online safety behaviour: towards an intervention strategy for college students

How can young adults be motivated to enact security precautions? Communication about the risks of Internet use or online safety communication is a context in which personal responsibility is especially salient. The present research builds on Protection Motivation Theory (PMT) to examine the role of a previously unexplored variable, personal responsibility, in the protective behaviour of college students. Two studies are reported here. In the first (N?=?565), the relationship of personal responsibility to safe (i.e. protective) online behaviour is tested in relationship to standard PMT variables. A multiple regression analysis of survey data shows that personal responsibility explained additional variance in protective behaviour after accounting for the effects of traditional threat and coping appraisal variables. Building on this, the second study (N?=?206) examines the possibility of influencing personal responsibility through an intervention and experimental manipulation among college students. The experimental manipulation of personal responsibility found evidence of a causal relationship between personal responsibility and protective behaviour in the college student sample. Interactions with pre-existing levels of safety involvement and self-efficacy were uncovered. Based on the results, strategies for targeted online safety interventions are suggested.     

Quasi‐isothermal DSC testing of epoxy adhesives using initial fast heating rates

Three major factors decrease the accuracy of the cure measurement in standard‐isothermal testing using differential scanning calorimetry (DSC). First, cure occurs during the heating step. Second, data are lost during the stabilization period between the dynamic and isothermal step. Third, the baseline selection requires a modification to the protocol. An alternative, which is explored in this study, is the use of fast ramps, which decrease the heating time, but this has been avoided due to overshoot that occurs between the dynamic and isothermal step, which is troublesome for systems with autocatalytic kinetics. By mitigating these factors, a quasi‐isothermal protocol was developed. Therefore, more complete cure kinetics were captured with the implementation of fast DSC to decrease the ramp time and through the optimization of furnace parameters to decrease stabilization time and temperature overshoot. The data suggested this quasi‐isothermal analysis more accurately measured the isothermal curing kinetics of a commercial epoxy adhesive at 110, 115, and 120 °C for fast ramps of 175, 350, and 500 K/min compared to the traditional ramp of 5 K/min. The enthalpy spike at the dynamic to isothermal transition remains an issue; however, an empirical shift can be used to compensate for the enthalpy signal lag. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45425.     

Composites of polymeric gels and magnetic nanoparticles: Preparation and drug release behavior

The article is concerned with the preparation of polymer–iron oxide nanocomposites and the study as drug‐delivery matrices under the influence of applied magnetic field. Biocompatible materials were prepared by incorporating an aqueous ferrofluid in poly(vinyl alcohol) and scleroglucan (SCL) hydrogels, loaded with theophylline as model drug for release studies. The in vitro release profile was obtained using a flat Franz cell and the kinetic parameters were derived applying a semiempirical power law. A magnetic characterization of nanoparticles contained in the ferrofluid was performed by obtaining the magnetization curve. For both systems, the observed drug release profiles decreased when a uniform external magnetic field is applied suggesting they can be used as environmental responsive matrices for biomedical applications. Dynamic rheological measurements show that a higher storage modulus and a more compact structure are obtained by incorporating the ferrofluid into the hydrogels. These rheological results and environmental electron scanning microscopy micrographs point to an understanding of release behavior once the magnetic field is applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of the calcium on the textural, structural and catalytic properties of La1–x Ca x Co1–y Fe y O3 perovskites

In La_1-x Ca _x Co_1-y Fe _y O₃ perovskites, the calcium substitution modifies the crystalline structure toward a pseudocubic one and produces an electronic unbalance, compensated by the formation of oxygen vacancies and Fe⁴⁺ ions. It also increases slightly the ethanol conversion in total combustion, compensating the detriment of catalytic activity caused by the iron substitution and it increases notably the selectivity to total oxidation.