Sensitivities of detonating compounds to frictional impact,impact, and heat

Using standardized tests, the sensitivities of twenty compounds and two mixtures to frictional impact, impact, and heat have been studied and recorded. The results show that values obtained by one test are not paralleled by those of either of the other two tests, but that, on division into classes, averages indicating a general correlation are obtained.     

An integrated microfluidic bubble pocket for long-term perfused three-dimensional intestine-on-a-chip model

Perfused three-dimensional (3D) cultures enable long-term in situ growth and monitoring of 3D organoids making them well-suited for investigating organoid development, growth, and function. One of the limitations of this long-term on-chip perfused 3D culture is unintended and disruptive air bubbles. To overcome this obstacle, we invented an imaging platform that integrates an innovative microfluidic bubble pocket for long-term perfused 3D culture of gastrointestinal (GI) organoids. We successfully applied 3D printing technology to create polymer molds that cast polydimethylsiloxane (PDMS) culture chambers in addition to bubble pockets. Our developed platform traps unintended, or induced, air bubbles in an integrated PDMS pocket chamber, where the bubbles diffuse out across the gas permeable PDMS or an outlet tube. We demonstrated that our robust platform integrated with the novel bubble pocket effectively circumvents the development of bubbles into human and mouse GI organoid cultures during long-term perfused time-course imaging. Our platform with the innovative integrated bubble pocket is ideally suited for studies requiring long-term perfusion monitoring of organ growth and morphogenesis as well as function.     

Teacher pedagogical content knowledge,practice, and student achievement†

ABSTRACT

In this exploratory study, we attempted to measure potential changes in teacher knowledge and practice as a result of an intervention, as well as trace such changes through a theoretical path of influence that could inform a model of teacher professional knowledge. We created an instrument to measure pedagogical content knowledge (PCK), studied the impact of a two-year professional development intervention, explored the relationships among teacher variables to attempt to validate a model of teacher professional knowledge, and examined the relationship of teacher professional knowledge and classroom practice on student achievement. Teacher professional knowledge and skill was measured in terms of academic content knowledge (ACK), general pedagogical knowledge (GenPK), PCK and teacher practice. Our PCK instrument identified two factors within PCK: PCK-content knowledge and PCK-pedagogical knowledge. Teacher gains existed for all variables. Only GenPK had a significant relationship to teacher practice. ACK was the only variable that explained a substantial portion of student achievement. Our findings provide empirical evidence that we interpret through the lens of the model of teacher professional knowledge and skill, including PCK [Gess-Newsome, J. (2015). A model of teacher professional knowledge and skill including PCK: Results of the thinking from the PCK summit. In A. Berry, P. Friedrichsen, & J. Loughran (Eds.), Re-examining pedagogical content knowledge in science education (pp. 28–42). London: Routledge Press], highlighting the complexity of measuring teacher professional knowledge and skill.     

Managing Sudden Loss

Managers often face tough, emotional situations at work. One of the biggest is guiding employees and departments successfully through the loss of a coworker. Not only are there emotional components but there are also more technical and procedural responsibilities that may be overlooked. These facilities, technological, and human resources tasks need to be handled sensitively and in a timely manner. Remembering whom to contact, what property needs to be considered, and how to produce final paychecks are just a few of the concerns managers will face in a trying time. This guide aims to serve as a checklist of the basic components and tasks managers will face after the sudden loss of an employee.