Water-soluble UV curable urethane methyl acrylate coating: preparation and properties

Two kinds of water-soluble and ultraviolet (UV) curable oligomers were synthesized and characterized. The oligomers were evaluated as resins for water-based UV curable coating. The rheology of the two oligomers' aqueous solutions was investigated in terms of solid fraction, pH dependence, and temperature dependence. The solutions were found to be Newtonian fluid showing rather low viscosity even at high solid fraction of 0.55. The drying process of the coatings and the properties of the cured coatings were studied by comparing them with water-dispersed UV-curable polyurethane methyl acrylate. It was evident that the water-soluble coating dried more slowly; and that the overall properties were inferior to those of the water-dispersed coating.     

Influence of hydroxypropyl methylcellulose edible coating on fresh-keeping and storability of tomato

The effect of application of cellulose-based edible coating, hydroxypropyl methylcellulose (HPMC) to mature-green tomatoes on the firmness and color was investigated. Tomatoes were stored at 20°C for up to 18 days. Firmness decreased as storage time increased in all treatments. However, application of HPMC edible coating delayed softening of tomatoes during 18 days of storage at 20°C. At days 7, 13 and 18, the firmness of tomatoes coated with HPMC was significantly (P≦0.05) greater than the firmness of uncoated tomatoes. The study also confirmed that HPMC coatings could significantly (P≦0.05) delay the changes in color of tomatoes stored at 20°C. The ripening of tomatoes from the pink stage to the red stage was successfully retarded. HPMC coating could extend the shelf life of fresh tomatoes. The retardation of the rate of loss of firmness could reduce the economic loss that would result from spoilage by mechanical injury during transportation of tomatoes. Project partly supported by the Centers for Disease Control and Prevention, U.S. Public Health Service     

Using time dynamically in static intervals: Does it close the achievement gap?

A mixed-methods study was undertaken with 118 biology students in two urban high schools. A Student-Centered Adaptable Learning Environment (SCALE) was created to improve engagement from affective and cognitive perspectives using choice, creativity and technological allowances. Results demonstrated that fast and slow learners are generally separated by about 30 min in terms of inputting speeds, but can be as much as 65 min apart from one another. Given that traditional classrooms afford students only 45 min in which to learn, static time could have become a source of inequity in public schools. SCALE optimally allowed for the dynamic use of time in constrained periods, therefore reducing and even eliminating any negative relationships between speed of learning and resultant achievement gains in the block setting. Especially benefitting from their ability to maneuver were the slowest learners, who showed the largest achievement improvements in either time interval amongst ability groupings. As learning speed can be the most critical contributing component of resultant educational outcomes, providing students the ability to use time dynamically should be considered as a feasible solution to helping teachers reestablish equity in mixed-ability classrooms in public schools.     

投桃授荑 抛梅掷李——《诗经》赠遗兴象的民俗文化内涵

由《诗经》的花草果蔬等兴象可见出先秦婚恋习俗中的赠遗之风。初时 ,女子多任采集之责 ,故蔬果花草之属为女子用于赠答致爱、结恩定情甚是便宜 ,或以芍药、梅子、茅草等取用为求偶媒介 ,或以桃子、花椒等取意于繁殖性能 ,使自然界中的极普遍之物因寓含了特殊而神秘的象征意蕴而别有价值 ,另具风味。     

Towards the Victimless School: Power,Professionalism and Probity in Teaching

This paper argues the importance of moving beyond the state of affairs that makes victims either of children or of teachers by exploring the conditions of possibility for the idea of a victimless school. The argument is developed drawing data from a study being conducted by the authors into the impact of risk management on teacher work and identity in a number of Australian primary schools (McWilliam, Singh & Sachs, 2002 Managing Risk in Primary Schools: Teachers professional Identity and Work Practices, ARC Discovery Project Funded by the Australian Research Council). The argument put is that risk minimisation as a system of management and surveillance (including self-surveillance) is producing some effects (whether intended or not) that are counterproductive for teachers and, indeed, for children, the very group they are purported to protect. In order to counter the more pernicious effects of this logic, teachers need actively to engage in seeking ways to optimise child protection and staff protection simultaneously.     

Instructional approaches to foster third graders’ adaptive use of strategies: an experimental study on the effects of two learning environments on multi-digit addition and subtraction

The adaptive use of strategies, that is selecting a strategy which allows an efficient solution for a given problem, can be considered as an important individual ability relevant in various domains. Based on models of subjects’ skills of adaptive use of strategies, two idealized instructional approaches are suggested to foster students in their strategy development. The explicit approach aims at reducing cognitive load by demonstrating and practicing strategies combined with an explicit identification of criteria for strategy efficiency by contrasting problem solutions. The implicit approach capitalizes on the generation effect and stimulates students to generate their own strategies and efficiency criteria based on the analysis of task characteristics and the comparison of problem solutions. In a 1-week experimental study (16 lessons) with 73 third-graders, we examined the effectiveness of these instructional approaches in the domain of multi-digit addition and subtraction. Results from post- and two follow-up tests after 3 and 8?months did not yield different effects of the two approaches on students’ skills in adaptive use of strategies. A comparison of strategies used by the students showed that the students of the explicit approach more frequently applied complex strategies whereas the students from the implicit approach showed a more sustainable use of self-generated strategies. Hence, for the adaptive use of those strategies students are able to generate, the implicit approach turned out to be more effective than the explicit approach. However, this generation effect does not hold for strategies which are too complex to be generated by students.     

Simulations of a modified SOP model applied to retrospective revaluation of human causal learning

Dickinson and Burke (1996) proposed a modified version of Wagner’s (1981) SOP associative theory to explain retrospective revaluation of human causal judgments. In this modified SOP (MSOP), excitatory learning occurs when cue and outcome representations are either both directly activated or both associatively activated. By contrast, inhibitory learning occurs when one representation is directly activated while the other is associatively activated. Finite node simulations of MSOP yielded simple acquisition, overshadowing, blocking, and inhibitory learning under forward contingencies. Importantly, retrospective revaluation was predicted in the form of unovershadowing and backward inhibitory learning. However, MSOP did not yield backward blocking. These predictions are evaluated against the relevant empirical evidence and contrasted with the predictions of other associative theories that have been applied to retrospective revaluation of human causal and predictive learning.     

Using an Ecological Framework for Understanding and Treating Externalizing Behavior in Early Childhood

This paper will review the literature on the rate, stability, and outcomes associated with externalizing behavior problems prior to kindergarten entry. Bronfenbrenners (The ecology of human development. Cambridge, MA: Harvard University Press) ecological framework will be used to present the factors related to the onset and persistence of externalizing behavior problems in young children. Behavior problems prior to school entry are somewhat developmentally appropriate and most can be resolved within the classroom or child care setting. Intervention for children with moderate to severe behavior problems in early childhood is crucial because behavior problems are likely to persist into elementary school leading to a variety of social and academic concerns. Steps will be presented to help teachers determine whether or not a referral to a specialist is needed and locate an appropriate specialist.     

Persecution and behavior: a report of refugee children from Chile

A Swedish study of 50 newly resettled refugee children from Chile describes the children's experiences of persecution in their home country and coping patterns in the receiving country. Thirty-six children had experiences directly related to persecution, and seven of these had been victims of physical assault for political reasons. Sleep disturbances and dependency were behaviors significantly associated with experiences of persecution. Resettled refugee families need to be approached by concerned professionals as symptoms of trauma in refugee children are often recognized only in the family sphere.