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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.

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.

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.