Biosurfactants production by yeasts using soybean oil and glycerol as low cost substrate

Biosurfactants are bioactive agents that can be produced by many different microorganisms. Among those, special attention is given to yeasts, since they can produce many types of biosurfactants in large scale, using several kinds of substrates, justifying its use for industrial production of those products. For this production to be economically viable, the use of residual carbon sources is recommended. The present study isolated yeasts from soil contaminated with petroleum oil hydrocarbons and assessed their capacity for producing biosurfactants in low cost substrates. From a microbial consortium enriched, seven yeasts were isolated, all showing potential for producing biosurfactants in soybean oil. The isolate LBPF 3, characterized as Candida antarctica, obtained the highest levels of production - with a final production of 13.86 g/L. The isolate LBPF 9, using glycerol carbon source, obtained the highest reduction in surface tension in the growth medium: approximately 43% of reduction after 24 hours of incubation. The products obtained by the isolates presented surfactant activity, which reduced water surface tension to values that varied from 34 mN/m, obtained from the product of isolates LBPF 3 and 16 LBPF 7 (respectively characterized as Candida antarctica and Candida albicans) to 43 mN/m from the isolate LPPF 9, using glycerol as substrate. The assessed isolates all showed potential for the production of biosurfactants in conventional sources of carbon as well as in agroindustrial residue, especially in glycerol.

Spinning reserve opportunity cost in hydroelectric plants

Starting from the deregulated process of the Electric Sector, there was the need to attribute responsibilities to several agents and to elaborate appropriate forms of remuneration of the services rendered by the same. One of the services of great importance within this new electric sector is the Ancillary Services. Among the various types of Ancillary Services, Spinning Reserve is a service necessary for maintaining the integrity of the transmission system from either generation interruptions or load variations. This paper uses the application of the Economic Dispatch theory with the objective of quantifies the availability of Spinning Reserve supply in hydroelectric plants. The proposed methodology utilizes the generating units as well as their efficiencies so as to attend the total demand with the minimum water discharge. The proposed methodology was tested through the data provided by the Água Vermelha Hydroelectric Power Plant. These tests permitted the opportunity cost valuation to the Spinning Reserve supply in hydroelectric plants. © 2005 IEEE.

Low cost technology applied to thermometry of grains

Modern agriculture demands investments in technology that allows the farmers to improve productivity and quality of their products, aiming to establish themselves in a competitive market. However, the high costs of acquiring and maintaining such technology may be an inhibiting factor to its spread and acceptance, mainly to a large number of small grain Brazilian farmers, who need low cost innovative technological solutions, suitable for their financial reality. Starting from this premise, this paper presents the development of a low cost prototype for monitoring the temperature and humidity of grains stored in silos, and the economic implications of cost/benefit ratio of innovative applications of low cost technology in the process of thermometry of grains. The prototype was made of two electronic units, one for acquisition and another one for data reception, as well as software, which offered the farmers more precise information for the control of aeration. The data communication between the electronic units and the software was reliable and both were developed using low cost electronic components and free software tools. The developed system was considered as potentially viable to small grain Brazilian farmers; it can be used in any type of small silos. It provided reduction of costs of installation and maintenance and also offered an easy expansion system; besides the low cost of development when compared to similar products available in the Brazilian market.

Cost-effectiveness comparison between pituitary down-regulation with a gonadotropin-releasing hormone agonist short regimen on alternate days and an antagonist protocol for assisted fertilization treatments

Objective: To compare cost-effectiveness between pituitary down-regulation with a GnRH agonist (GnRHa) short regimen on alternate days and GnRH antagonist (GnRHant) multidose protocol on in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) outcome. Design: Prospective, randomized. Setting: A private center. Patient(s): Patients were randomized into GnRHa (n = 48) and GnRHant (n = 48) groups. Intervention(s): GnRHa stimulation protocol: administration of triptorelin on alternate days starting on the first day of the cycle, recombinant FSH (rFSH), and recombinant hCG (rhCG) microdose. GnRHant protocol: administration of a daily dose of rFSH, cetrorelix, and rhCG microdose. Main Outcome Measure(s): ICSI outcomes and treatment costs. Result(s): A significantly lower number of patients underwent embryo transfer in the GnRHa group. Clinical pregnancy rate was significantly lower and miscarriage rate was significantly higher in the GnRHa group. It was observed a significant lower cost per cycle in the GnRHa group compared with the GnRHant group ($5,327.80 ± 387.30 vs. $5,900.40 ± 472.50). However, mean cost per pregnancy in the GnRHa was higher than in the GnRHant group ($19,671.80 ± 1,430.00 vs. $11,328.70 ± 907.20). Conclusion(s): Although the short controlled ovarian stimulation protocol with GnRHa on alternate days, rFSH, and rhCG microdose may lower the cost of an individual IVF cycle, it requires more cycles to achieve pregnancy. Clinical Trial Registration Number: NCT01468441. © 2013 by American Society for Reproductive Medicine.

Energetic cost of digging behavior in workers of the leaf-cutting ant Atta sexdens (Fabricius)

Energetic cost of digging behavior in workers of the leaf-cutting ant Atta sexdens (Fabricius). During nest excavation, leaf-cutting ant workers undergo reduction in their body reserve, particularly carbohydrates. In order to estimate the energetic cost of digging, groups of 30 workers of the leaf-cutting ant Atta sexdens were sealed in a hermetic chamber for 24, 48 and 72 hours, with and without soil for digging, and had the CO2 concentration measured using respirometric chambers as well as volume of soil excavated (g). As expected, the worker groups that carried out soil excavation expelled more carbon dioxide than the groups that did not excavate. Therefore, a worker with body mass of 9.65 ± 1.50 mg dug in average 0.85 ± 0.27 g of soil for 24 hours, consuming ca. 0.58 ± 0.23 J. In this study, we calculate that the energetic cost of excavation per worker per day in the experimental set-up was ca. 0.58 J.

Biosurfactants production by yeasts using soybean oil and glycerol as low cost substrate

Biosurfactants are bioactive agents that can be produced by many different microorganisms. Among those, special attention is given to yeasts, since they can produce many types of biosurfactants in large scale, using several kinds of substrates, justifying its use for industrial production of those products. For this production to be economically viable, the use of residual carbon sources is recommended. The present study isolated yeasts from soil contaminated with petroleum oil hydrocarbons and assessed their capacity for producing biosurfactants in low cost substrates. From a microbial consortium enriched, seven yeasts were isolated, all showing potential for producing biosurfactants in soybean oil. The isolate LBPF 3, characterized as Candida antarctica, obtained the highest levels of production - with a final production of 13.86 g/L. The isolate LBPF 9, using glycerol carbon source, obtained the highest reduction in surface tension in the growth medium: approximately 43% of reduction after 24 hours of incubation. The products obtained by the isolates presented surfactant activity, which reduced water surface tension to values that varied from 34 mN/m, obtained from the product of isolates LBPF 3 and 16 LBPF 7 (respectively characterized as Candida antarctica and Candida albicans) to 43 mN/m from the isolate LPPF 9, using glycerol as substrate. The assessed isolates all showed potential for the production of biosurfactants in conventional sources of carbon as well as in agroindustrial residue, especially in glycerol.