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Butanol and 1,3-propanediol (1,3-PDO) are simultaneously produced by Clostridium pasteurianum from glycerol. In this study, random chemical mutagenesis of C. pasteurianum DSM 525 was conducted to improve its tolerance to butanol. Selected nutritional and operational parameters were evaluated to identify strategies that favour the production of each metabolite. From those experiments, it was possible to isolate cells able to produce 22% more butanol than the parent strain in serum bottles. The supplementation of the culture medium with 2mgl of iron increased the production of butanol by 163%, and the optimum inoculum age was found to be 12hours. Overall, the experiments conducted in bioreactor led to lower butanol titers than in serum bottles, which is attributed to the higher pressure present in the bottles. At pH 6.0, N sparging notoriously favoured the production of biomass and 1,3-PDO, while a lower pH (5.0) led to a higher butanol yield, although growth was negatively affected. The results herein gathered allowed the identification of specific conditions that favour the production of either butanol or 1,3-PDO. Furthermore, it was found that N sparging is a suitable strategy to maximize the titer, yield and productivity of 1,3-PDO using C. pasteurianum.

We use a county-level panel dataset from 2012 to 2018 to assess the impacts of various state policies on total and rural broadband availability in the United States. The primary dependent variable is the percentage of residents with access to 25 Megabits per second (MBPS) download and 3 MBPS upload speeds via a fixed connection, with alternative specifications considering other aspects of availability such as technology type and competition. We control for the main determinants of Internet availability such as income, education, age, and population density. Our policy variables come from the newly released State Broadband Policy Explorer from the Pew Charitable Trusts and individual contacts from the nationwide State Broadband Leaders Network. Our primary policies of interest are those related to: (1) availability of state-level funding, (2) existence of a state-level broadband office/task force with full-time employees, and (3) restrictions on municipal/cooperative broadband provision. We find a positive and significant impact of state-level funding programs on general (and fiber) broadband availability, and a negative impact of municipal/cooperative restrictions. The findings are similar when the analysis is restricted to the rural portions of counties.

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High production yields and productivities are requisites for the development of an industrial butanol production process based on biodiesel-derived crude glycerol. However, impurities present in this substrate and/or the concentration of glycerol itself can affect the microbial metabolism. In this work, the effect of crude glycerol concentration on the production of butanol and 1,3-propanediol (1,3-PDO) by Clostridium pasteurianum DSM 525 is studied. Also, the effect of acetate and butyrate supplementation to the culture medium and the culture medium composition are evaluated. The results showed a marked effect of crude glycerol concentration on the product yield. The competitive nature of butanol and 1,3-PDO pathways has been evident, and a shift to the butanol pathway once using higher substrate concentrations (up to 35 g l À1) was clearly observed. Butyrate supplementation to the culture medium resulted in a 45% higher butanol titre, a lower production of 1,3-PDO and it decreased the fermentation time. Acetate supplementation also increased the butanol titre but the fermentation was longer. Even though glycerol consumption could not be increased over 32 g l À1 , when the concentrations of NH 4 Cl and FeCl 2 were simultaneously increased, the results obtained were similar to those observed when butyrate was supplemented to the culture medium; a 35% higher butanol yield at the expense of 1,3-PDO and a shorter fermentation. The results herein gathered suggest that there are other factors besides butanol inhibition and nutrient limitation that affect the glycerol consumption.

The impact of broadband access and use continues to transform the socioeconomic landscape placing this twenty-first century infrastructure at the center of current policymaking discourse. Past studies have found a relationship between infrastructure investments and economic productivity. Recent broadband-related studies, however, have focused on general availability or adoption, and do not distinguish which specific aspect of the technology is most associated with productivity. Utilizing crosssectional county-level data from 2017 and spatial econometric models, this research looked into better understanding the impact of multiple broadband indicators on job productivity, including innovative broader measures of digital inclusion. Results indicate that broader metrics focused on adoption or digital distress had a larger positive impact on job productivity in comparison to measures focused on speed or availability. Moreover, these impacts vary across urban and rural settings. Although the relationships identified are not necessarily causal, an alternative matching technique generally supports the results. These findings suggest that the relationship between broadband and economic productivity should be viewed from a larger, more comprehensive socioeconomic perspective. Future research should focus on looking at these effects over time and assess how policies focused on specific broadband characteristics have impacted growth.

Telework, or telecommuting, is gaining increasing attention at the national level. However, the impact it has on local economies is not well understood. Theoretically, teleworking may result in higher levels of worker satisfaction and productivity, which in turn leads to increased income levels. In an effort to contribute to this important topic, this paper analyses census‐tract level work from home statistics from the 2011–2015 American Community Survey. Results from a maximum likelihood regression using a spatial Durbin error model (SDEM) indicate that after controlling for various factors such as employment by industry, educational attainment, and broadband availability, the percentage of residents working from home in both salaried and self‐employed jobs had a positive and significant impact on median household income. Importantly, spillovers from levels of telework in neighbouring communities are also shown to exist, although the direction of impact differs by worker category. The implications of this research support the need to modify current economic and workforce development policies to better nurture, attract, and retain teleworkers. A series of policy recommendations are discussed to help jumpstart this process.