Almost Gorenstein rings

The notion of almost Gorenstein ring given by Barucci and Fr{\"o}berg \cite{BF} in the case where the local rings are analytically unramified is generalized, so that it works well also in the case where the rings are analytically ramified. As a sequel, the problem of when the endomorphism algebra \m : \m of \m is a Gorenstein ring is solved in full generality, where \m denotes the maximal ideal in a given Cohen-Macaulay local ring of dimension one. Characterizations of almost Gorenstein rings are given in connection with the principle of idealization. Examples are explored

授業外のタスク取り組みを促進するためのソーシャル・インタラクションでのティーチャー・プレゼンスの役割

早大学位記番号:新8282早稲田大

COPPER AND LEAD RECOVERY FROM DISCARDED PRINTED CIRCUIT BOARDS BY ELECTROLYSING LEACHED SOLUTION

Results of copper and lead recovery from discarded printing circuit boards (PCB) by acidic dissolution and electrodeposition are presented. A preliminary procedure of the recovery process is proposed with the following steps: disposal of the mounted electrical elements, cleaning, grinding, iron separation for grains screening, metal dissolution, and electrolysis. The composition analysis is performed to define suitable electrochemical parameters for recovery. XRF and AAS techniques are used for preliminary estimation of metal content in leached solution. LSV method is implemented to establish parameters for copper electrodeposition. The product quality is evaluated through XRD analysis. The high recovery efficiencies, 97.61% and 96.59 % for copper (in metallic form) and lead (in dioxide form), respectively, were reached.

A Case Study of How Visually Impaired Learners Acquire Language

The field of second language acquisition has grown enormously in the past decades. Many studies have been done on how learners acquire English as a second language; however, research on how visually impaired learners acquire English as a second or foreign language has been relatively scarce. It is even more difficult to find such studies in Vietnam. Based mainly on in-depth interviews with two visually impaired Vietnamese adults who have been successful in acquiring English, the present study seeks to answer two main questions: (1) How Vietnamese visually impaired learners acquire English as a second language; (2) What difficulties they have in learning English, and how they overcome their difficulties. The findings of the present study can contribute to the theory of second language acquisition and language teaching. The study can also provide strategies for practicing and learning a language not only for visually impaired learners but also for second language learners in general