No description available.

Compared to other instruments for chemical analyses, electrochemical analyzers are relatively simple, inexpensive, easy to miniaturize and require little-to-no maintenance. However, like all commercially available instruments, commercial electrochemical analyzers like potentiostats primarily operate as black boxes with manufacturers providing little or no information about internal circuitry and programming. This practice can limit a researcher’s ability to develop new techniques or adapt an instrument for applications outside its typical use. In contrast, creators of open-source instruments release all the necessary information for reproduction of the hardware and software – minimizing such barriers to innovation in chemical analyses. Here, we report a low-cost, compact potentiostat based on an open-source Arduino microcontroller capable of performing electrochemical analyses such as cyclic and linear sweep voltammetry with an operating range of ± 208 𝜇A and ± 2.5 V. Performance of the potentiostat is investigated with low-cost pencil graphite electrodes and compared to a commercial potentiostat.

Algae extracts are used as cosmetic products and used as additives in specific foods because of their antioxidant activity. Reactive oxygen species (ROS) such as hydrogen peroxide and superoxide radicals are toxic on the skin and can be scavenged by antioxidants, which are abundant in microalgae. Antioxidant substances protect the skin against external factors such as ultraviolet light (UV). Many creams that are concerned with treating the skin have antioxidant molecules. Researchers are performing many studies to achieve natural and non-chemical skin maintenance for the skin. Conducting in vivo studies to analyze the antioxidant potential of extracts on skin needs ethical permission to recruit a specific number of people. In this study, pig ear skin was used with the help of a skin-membrane-covered oxygen electrode (SCOE) to analyze the antioxidant effect of an extract from the microalgae Chlamydomonas reinhardtii. A study proved that this method was effective in measuring other antioxidants. Hydroquinone was used as a control to see if the system worked correctly. Hydroquinone showed that it could penetrate the skin and give antioxidant activity. When the algae extract was used, the same effect as for hydroquinone could not be detected. With a 2,2-diphenylpicrylhydrazyl (DPPH) assay, the algae extract was analyzed for its antioxidant capacity, and the assay revealed a positive antioxidant effect of the extract. The spectrophotometric measurement of the amount of bioactive antioxidant molecules in the extract in different solutions suggested that the one resuspended in ethanol presented a higher amount of carotenoids and chlorophylls than the extract resuspended in an aqueous buffer. Additional research will be needed to characterize the antioxidant potential of the extract from the microalgae Chlamydomonas reinhardtii.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24633号 / 工博第5139号 / 新制||工||1982(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 安部 武志, 教授 阿部 竜, 教授 作花 哲夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24635号 / 工博第5141号 / 新制||工||1982(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 佐藤 啓文, 教授 作花 哲夫, 教授 寺村 謙太郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

This research reports on the fabrication and characterization of integrated dual nanometer-sized electrodes. The electrodes are made of closely spaced nanometer-sized platinum and gold achieved by inserting and pulling platinum wire in cylindrical glass pipette plated with gold. Cyclic voltammetry has been used to characterize the electrodes. Our results show that both electrodes can work individually and can accomplish generation/collection experiments. Factors that may affect the performance of the electrodes as well as formation mechanism of the gold film by electroless plating are discussed.

Context: Electrodes play an important role in interfacing tissue with electrical stimulation devices. Manufacturers recommend that adhesive metallic mesh cloth electrodes be used no more than 10 times before they are discarded, however, clinically the electrodes are often used up to 30 times. Another concern is sanitation. When electrodes are used on different patients, there is a chance for cross-contamination and bacterial growth on the electrode. Objective: To compare amplitudes of perceived sensation, motor twitch and force produced at specific amplitudes using single-use electrodes that run no risk of cross-contamination, and multiple-use electrodes. Design: Mixed model ANOVA with the subject blocked. Setting: Therapeutic modalities research laboratory. Patients or Other Participants: 20 subjects comprised of 7 males (age 24.7 yrs ± 2.3 yrs, skin fold thickness 5.9 mm ± 2.4 mm) and 13 females (age 21.5 yrs ± 2.3 yrs, skin fold thickness 10.7 mm ± 4.1 mm) recruited by volunteer sample mainly from athletic and athletic training populations. They drew random numbers to determine which group they were assigned to. Interventions: Each subject had electrodes placed on their wrist extensors muscles. Measures were recorded of what intensity it took to achieve perceived sensation, motor twitch, and force produced at a specific intensity. To determine decay, multiple use electrodes were tested initially and on the 10th use. After the multiple use electrodes were tested initially, they were leached out. After eight uses, pretest procedures were repeated (10th use electrode) as the final trial on the subjects. Single use electrodes were tested one time. Main Outcome Measures: The dependent variables were sensation, motor twitch and force production. The experiment was a repeated measures study, using mixed models ANOVA with subjects blocked. Alpha was set at p<0.05. Data was analyzed using a SAS proc mixed 9.1. Results: There was no statistical difference between the measures taken during the initial trial and final trial of the multiple use electrodes for muscle twitch (FMUI MUF muscle twitch= 107.3, p= 0.09) and force production (FMUI MUF force production=28.7, p= 0.11). There was a significant difference between the single use and the multiple use electrodes for the initial and final trial. Average values in mA for perceived sensory were: single use 9.73, multiple use initial 16.70 , multiple use final 21.03; observed muscle twitch: single use 15.87, multiple use initial 29.16, multiple use final 31.78; and force produced: single use 22.8 Newtons, multiple use initial 10.0 Newtons, multiple use final 5.0 Newtons. Conclusion: Single-use electrodes produce more conductive power with fewer milliamps compared to multiple-use electrodes. Single use electrodes are just as, or more efficient as the multiple use electrodes and have the added advantage of eliminating the possibility of cross-contamination of bacteria from patient to patient.

Electrochemical measurements are utilized in various fields, including healthcare (e.g., potentiometric measurements for electrolytes in blood and blood gas, amperometric biosensing of glucose as in blood glucose meters), water quality (e.g., pH measurement, voltammetric analyses for heavy metals), and energy. Much of the appeal of electrochemical analyses can be attributed to the relative simplicity, low cost and lack of maintenance associated with electrochemical instruments, along with techniques that can exhibit high sensitivity and selectivity, wide linear dynamic range, and low limits of detection for many analytes. While commercial electrochemical analyzers are less expensive than many other instruments for chemical analyses and are available from various manufacturers, versatility and performance often coincide with added expense. Recently, the development of low-cost, adaptable, open-source chemical instruments, including electrochemical analyzers, has emerged as a topic of great interest in the scientific community. In contrast to commercial instruments, for which schematics and underlying operation details are often obscured – severely limiting modifications and improvements, creators of open-source instruments release all the necessary information for reproduction of the hardware and software. As a result, open-source instruments not only serve as excellent teaching tools for novices to gain experience in electronics and programming, but also present opportunity to design and develop low-cost, portable instruments, which have particular significance for point-of-care sensing applications, use in resource-limited settings, and the rapidly developing field of on-body sensors. In this work, we report the design of a low-cost, compact electrochemical analyzer based on an open-source Arduino microcontroller. The instrument is capable of performing electrochemical analyses such as cyclic and linear sweep voltammetry with an operating range of ± 138 ��A and ± 1.65 V. Performance of the platform is investigated with low-cost pencil graphite electrodes and results compared to commercial potentiostats.

In this work we present a carbon free gas diffusion electrode (GDE) design. It is a first step towards improvement of technologies like alkaline fuel cells, some alkaline electrolyzes and metal-air-batteries by circumventing carbon degradation. A nickel-mesh was made hydrophobic and subsequently electrochemically coated with MnOx as electrocatalyst. By this, a carbon free GDE was prepared. The contact angle, specific surface area (BET), pore size distribution, crystal phase (XRD) and electrochemical properties were determined. The deposition scan rate (rscan) during dynamic MnOx deposition altered the macro surface structure, pore size distribution and deposited mass. High catalyst masses with high specific surface area were achieved by lower rscan, but hydrophobicity was decreased. Impedance spectroscopy showed that higher MnOx mass will increase the ohmic resistance, because of the low conductivity of oxides, such as MnOx. The diffusion of dissolved oxygen is the major contributor to the total resistance. However, the polarization resistance was reduced by increased specific surface area of MnOx. It was concluded that the ORR and OER are limited by diffusion in this design but nevertheless showed reasonable activity for ±10 mA cm−2 corresponding to ∼8 Ω cm−2 while references exhibited ∼3.5 Ω cm−2 .

No description available.