How to evaluate science problem solving in a computerized learning environment? Construction of an analyzing scheme

Περιέχει το πλήρες κείμενοThis paper describes the construction of a ‘computerized science problem solving’ scheme, which enables analysis and evaluation of the effectiveness of science problem-solving by junior high-school students working in a computerized learning environment. The scheme was based on observations of 187 students as they solved qualitative science problems taken from a specific computerized learning environment. Students were also interviewed before and after the problem solving. The scheme is presented on two levels. The large-scale comprises 11 main categories, each sub-divided into sub-categories to yield the detailed-level. The sub-categories were based on a repertoire of activities found in the observation protocols, and were approved by external judgement and a validation process. The detailed-level scheme enables evaluation and statistical analysis of the participants' problem-solving effectiveness, providing substantial evidence for the construct validity of the scheme, and demonstrating its potential as a valid analyzing and evaluative tool for computerized science problem solving

Continuous-Flow Synthesis of N-Succinimidyl 4-[18F]fluorobenzoate Using a Single Microfluidic Chip

In the field of positron emission tomography (PET) radiochemistry, compact microreactors provide reliable and reproducible synthesis methods that reduce the use of expensive precursors for radiolabeling and make effective use of the limited space in a hot cell. To develop more compact microreactors for radiosynthesis of 18F-labeled compounds required for the multistep procedure, we attempted radiosynthesis of N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) via a three-step procedure using a microreactor. We examined individual steps for [18F]SFB using a batch reactor and microreactor and developed a new continuous-flow synthetic method with a single microfluidic chip to achieve rapid and efficient radiosynthesis of [18F]SFB. In the synthesis of [18F]SFB using this continuous-flow method, the three-step reaction was successfully completed within 6.5 min and the radiochemical yield was 64 ± 2% (n = 5). In addition, it was shown that the quality of [18F]SFB synthesized on this method was equal to that synthesized by conventional methods using a batch reactor in the radiolabeling of bovine serum albumin with [18F]SFB

Concepts for microfluidic syntheses that require multistep reactions.

<p>Concepts for microfluidic syntheses that require multistep reactions.</p

Design of chip 2 for a three-step reaction.

<p>Design of chip 2 for a three-step reaction.</p

Microreactor system developed in this study.

<p>Microreactor system developed in this study.</p

Synthetic method for [¹⁸F]SFB.

<p>Synthetic method for [¹⁸F]SFB.</p

Radiochemical yield of [¹⁸F]SFB by one-pot radiosynthesis under different water content conditions (data are the mean ± S.D., <i>n</i> = 3).

<p>Radiochemical yield of [¹⁸F]SFB by one-pot radiosynthesis under different water content conditions (data are the mean ± S.D., <i>n</i> = 3).</p

One-pot synthesis of [¹⁸F]SFB in (a) MeCN or (b) DMSO using a batch reactor (data are the mean ± S.D., <i>n</i> = 3).

<p>One-pot synthesis of [¹⁸F]SFB in (a) MeCN or (b) DMSO using a batch reactor (data are the mean ± S.D., <i>n</i> = 3).</p

(a) Microfluidic chip for three-step reaction (chip 2) and (b) conditions for continuous-flow synthesis of [¹⁸F]SFB.

<p>(a) Microfluidic chip for three-step reaction (chip 2) and (b) conditions for continuous-flow synthesis of [¹⁸F]SFB.</p

Radiolabeling of BSA with [¹⁸F]SFB synthesized using chip 2 (data are the mean ± S.D., <i>n</i> = 4).

<p>Radiolabeling of BSA with [¹⁸F]SFB synthesized using chip 2 (data are the mean ± S.D., <i>n</i> = 4).</p