私は本学において長らく1年生を対象とした「微分積分学および演習」「工学数学および演習」を担当してきましたが、この両科目では実数の範囲の微分、積分を扱い、そこに複素数の要素が入ってくることはほとんどありません。ただ使用している教科書1)の最後の章で定数係数2階微分方程式の解の説明（最近発売されている微分積分の教科書では、微分方程式まで扱われている微分積分の教科書はほとんど見かけません）でオイラーの公式が出現し、微分方程式の解に複素数の解が現れます。ご存じのようにオイラーの公式はその後の専門教育では頻繁に出てくる重要な式でありますが、複素数を扱う数学となると「複素関数論」という別の科目として扱われ、複素空間から始まり、複素積分までの範囲までと1年生にとっては難しい内容であり、応用化学科ではこのような科目は開講されていません。しかし現在ある微分積分学の内容に複素数の虚数単位であるiを特殊な性質を持った係数として扱うだけで、複素関数論で扱うような難しい内容とする必要はなく、三角関数の加法定理や微積分、マクローリン展開や各種の微分積分の公式が理解できると考えます。本論文（エッセイ）ではオイラーの公式および複素数を含めた各種の微分積分から始め、減衰振動の現象などの応用までについて思いついたまま記述していきます。

山口東京理科大学工学部3学科（機械工学科・電気工学科・応用化学科）の1年生向けに「物理学及び演習」（応用化学科は「物理学II及び演習」）として開講している電磁気学分野の入門的講義において，著者らが2022年度第IV期にそれぞれ担当したクラスの受講生に対し電磁気学についての概念調査(BEMA)のプレテスト及びポストテストを実施した結果に関して報告する。これは， 2019年度に2クラスのみで実施した調査の拡大版に相当する。本調査の問題は全問選択式の出題形式であり，オリジナル[Chabay-Sherwood(1997)］は英語で書かれているが，そのH本語版［土佐幸子訳(2014)］を使用した。ここでは，この調査のプレテスト・ポストテストの採点結果について統計的に処理し， 2019年度の結果との比較や学科依存性，入試形態依存性等の解析をする。さらに， BEMAを多次元項目反応理論で解析した文献[Hansen-Stewart(2021)]に具体的に記載されている2つのモデルを本調査の回答データに適用して解析する。以上の解析結果をまとめて報告し，コメントを述べる。

We conducted a questionnaire survey among students belonging to the Department of Electrical Engineering, Faculty of Engineering, Sanyo-Onoda City University between January 2021 and June 2021 regarding the use of learning support classroom. We asked 196 students and 188 (96%) responded. Forty-three students had used the service and 95% of them said that it was effective. Twenty of these students used the service only once, and it appears that they asked friends for advice on assignments and only used the service when there was a problem that they just couldn't answer. The analysis suggests that the students who used the service in this way generally used it as expected. On the other hand, as for the students who had not use the Learning Support Classroom, the majority of them seem to have solved their problems by asking their friends. However, when analyze by grade group, about 50% of the students in the upper half of the grade band answered that they had no problems with their studies, while only about 14% of the students in the lower half of the grade band answered that they had no problems. For these students, even though they did not think they had no problems, they felt that going to tutoring was a hassle or a chore, or that the hours were not convenient. In order to increase the number of users, it may be important to continue to consider the days that the room is open, to make announcements such as the orientation, and to increase opportunities to get to know the assistant professor.

While working at Sanyo-onoda City University, the author researched and invented the microbial fuel cell utilizing inorganic porous materials, which has a power generation capacity ten times greater than conventional ones. This achievement is attracting attention as an innovative technology that has the potential to replace or supplement the current electrical energy dependence on fossil fuels. After retiring from university, the author wanted to put the research results achieved at the former Morita laboratory into practical use in order to make a significant contribution to humanity's energy problems. Then, the author conducted the cooperating company in Tottori Prefecture that manufactures inorganic porous materials to carry out practical tests in a fallow field on the outskirts of Tottori City. From 2022 to 2023, 64 experimental microbial fuel cells were installed at the test site, and outdoor power generation data was obtained across seasons. During this period, we also conducted in the laboratory experiments to improve power generation and made improvements to problems that emerged during operation in natural environments. Furthermore, during this period, the electricity generated was used to light street- lamps and used for illumination during Christmas and cherry blossom viewing seasons, bringing us one step closer to practical application. At present, microbial power generation has not yet reached the point where it can replace commercial electricity, but it is suitable for use in remote areas, remote islands, and developing countries where electricity is not available, and as an emergency power source during disasters such as typhoons and heavy rain that have been occurring frequently in recent years. We believe that this technology can be put to practical use as a suitable power source in the situations described above.

The reflection and transmission characteristics of granular composite materials containing Cu or Ag-coated Cu flake-shaped particles were investigated by measurement in free space and by calculation based on transmission line theory. The negative permittivity spectra, which characterized the permittivity properties of metals, were observed in the Cu and Ag-coated Cu flake composites with particle contents above the percolation threshold Φc. For the Cu and Ag-coated Cu flake composites below Φc. the measured absolute values of the reflection coefficient |Γ| and the transmission coefficient ITI increased and decreased with increasing frequency, respectively. The Ag-coated Cu flake composite aboveりcexhibited metallic reflection and transmission characteristics with |Γ| > 0.9 and ITI < 0.1; these characteristics of the Ag-coated Cu flake composite agreed with the calculated results based on transmission line theory. Meanwhile, the measured values of |Γ| and ITI for the Cu flake composites above Φc tended to deviate from the theoretical values due to changes in electrical conductivity.