New Approach for the Construction and Calibration of Gas-Tight Setups for Biohydrogen Production at the Small Laboratory Scale.

Biohydrogen production in small laboratory scale culture vessels is often difficult to perform and quantitate. One problem is that commonly used silicon tubing and improvised plastic connections used for constructing apparatus are cheap and easy to connect but are generally not robust for gases such as hydrogen. In addition, this type of apparatus presents significant safety concerns. Here, we demonstrate the construction of hydrogen-tight apparatus using a commercially available modular system, where plastic tubing and connections are made of explosion-proof dissipative plastic material. Using this system, we introduce a gas chromatograph calibration procedure, which can be easily performed without necessarily resorting to expensive commercial gas standards for the calibration of hydrogen gas concentrations. In this procedure, the amount of hydrogen produced by the reaction of sodium borohydride with water in a closed air-filled bottle is deduced from the observed decrease of the oxygen partial pressure, using the ideal gas law. Finally, the determined calibration coefficients and the gas-tight apparatus are used for the analysis of simultaneous oxygen consumption and hydrogen production of the purple photosynthetic bacterium, Rhodospirillum rubrum, during semi-aerobic growth in the dark.

Perceived Changes in Mood and Anxiety Among Male Youth During the COVID-19 Pandemic: Findings From a Mixed-Methods Study.

PURPOSE: The coronavirus disease 2019 (COVID-19) pandemic has changed almost every aspect of our lives. Young adults are vulnerable to pandemic-related adverse mental health outcomes, but little is known about the impact on adolescents. We examined factors associated with perceived changes in mood and anxiety among male youth in urban and Appalachian Ohio. METHODS: In June 2020, participants in an ongoing male youth cohort study were invited to participate in an online survey that included questions about changes in mood, anxiety, closeness to friends and family, and the major impacts of the pandemic. Weighted log-binomial regression models were used to assess the risk of worsened mood and increased anxiety. Chi-square tests were used to examine the association between perceived changes in mood and anxiety and perceived changes in closeness to friends and family and open-ended responses to a question about COVID-19's impact on participants. RESULTS: Perceived worsened mood and increased anxiety during the pandemic were associated with higher household socioeconomic status, older age, feeling less close to friends and family, and reporting that COVID-19 negatively affected mental health. A perceived increase in anxiety was also associated with a history of symptoms of depression or anxiety. CONCLUSIONS: Specific subgroups of male youth may be at heightened risk of worsening mental health during the COVID-19 pandemic. Interventions should target vulnerable adolescents and seek to increase closeness to social contacts. Such efforts could involve novel programs that allow youth to stay connected to friends, which might mitigate the negative impact on mental health.

Going Once, Going Twice: Using Willingness-to-Accept Auctions to Promote Smoking Cessation.

INTRODUCTION: Incentive-based smoking cessation interventions increase quit rates. The optimal incentive, however, is unknown. We used a willingness-to-accept (WTA) auction where smokers submitted bids indicating the incentive they would need to receive for 1 week of smoking cessation. AIMS AND METHODS: Smokers ready to quit (n = 35) participated in a WTA auction, naming the amount they needed to be paid to quit for 1 week. Auction winners received an incentive if they successfully quit. All smokers received nicotine replacement therapy and self-help cessation materials. Carbon monoxide concentrations were monitored remotely three times during the week and in person at the final session. RESULTS: Participants who smoked their first cigarette within 5 min of waking demanded a significantly larger incentive in exchange for quitting than those who waited (p < .05). About 45% of auction winners quit smoking compared to 20% of nonwinners (p < .05). The cost per quit was $466 among auction winners compared to $894 among nonwinners. CONCLUSIONS: WTA auctions may be an effective way to determine the amount smokers need to be paid to quit, which would allow researchers to estimate the most cost-effective payment to offer as part of incentive-based smoking cessation programs. Replication evaluating longer-term cessation outcomes with larger samples is warranted. IMPLICATIONS: Incentive-based smoking cessation interventions increase quit rates. However, the optimal incentive is unknown. We found that a WTA auction is a feasible technique for estimating the amount smokers need to be paid to quit. Incentives are a surprisingly cost-effective way to facilitate smoking cessation because they are only paid to those who successfully quit. WTA auctions are a promising tool for determining the incentive that strikes the optimal balance between being large enough to motivate cessation, but small enough that it can be offered to the largest possible population of smokers for a given program budget.

A Modified Kulka Micromethod for the Rapid and Safe Analysis of Fructose and 1-Deoxy-d-xylulose-5-phosphate.

The Kulka resorcinol assay (Kulka, R.G., Biochemistry 1956, 63, 542⁻548) for ketoses has been widely used in the literature but suffers from two major disadvantages: (a) it employs large amounts of potentially harmful reagents for a general biology laboratory environment; and (b) in its original formulation, it is unsuited for modern high-throughput applications. Here, we have developed a modified Kulka assay, which contains a safer formulation, employing approx. 5.4 M HCl in 250 µL aliquots, and is suitable for use in high-throughput systems biology or enzymatic applications. The modified assay has been tested extensively for the measurement of two ketoses-fructose (a common substrate in cell growth experiments) and 1-deoxy-d-xylulose-5-phosphate (DXP), the product of the DXP-synthase reaction-which until now has only been assayable using time-consuming chromatographic methods or radioactivity. The Kulka microassay has a sensitivity of 0⁻250 nmol fructose or 0⁻500 nmol DXP. The assay is suitable for monitoring the consumption of fructose in bacterial growth experiments but is too insensitive to be used directly for the measurement of DXP in in vitro enzyme assays. However, we show that after concentration of the DXP-enzyme mix by butanol extraction, the Kulka resorcinol method can be used for enzyme assays.

A rapid procedure for the in situ assay of periplasmic, PQQ-dependent methanol dehydrogenase in intact single bacterial colonies.

Mechanistic details of methanol oxidation catalyzed by the periplasmically-located pyrroloquinoline quinone-dependent methanol dehydrogenase of methylotrophs can be elucidated using site-directed mutants. Here, we present an in situ colony assay of methanol dehydrogenase, which allows robotic screening of large populations of intact small colonies, and regrowth of colonies for subsequent analysis.