Ignition conditions for inertial confinement fusion targets with a nuclear spin-polarized DT fuel

The nuclear fusion cross-section is modified when the spins of the interacting nuclei are polarized. In the case of deuterium?tritium it has been theoretically predicted that the nuclear fusion cross-section could be increased by a factor d = 1.5 if all the nuclei were polarized. In inertial confinement fusion this would result in a modification of the required ignition conditions. Using numerical simulations it is found that the required hot-spot temperature and areal density can both be reduced by about 15% for a fully polarized nuclear fuel. Moreover, numerical simulations of a directly driven capsule show that the required laser power and energy to achieve a high gain scale as d-0.6 and d-0.4 respectively, while the maximum achievable energy gain scales as d0.9.

Yield, nutrient utilization and soil properties in a melon crop amended with wine-distillery waste

In Spain, large quantities of wine are produced every year (3,339,700 tonnes in 2011) (FAO, 2011) with the consequent waste generation. During the winemaking process, solid residues like grape stalks are generated, as well as grape marc and wine lees as by-products. According to the Council Regulation (EC) 1493/1999 on the common organization of the wine market, by-products coming from the winery industry must be sent to alcohol-distilleries to generate exhausted grape marc and vinasses. With an adequate composting treatment, these wastes can be applied to soils as a source of nutrients and organic matter. A three-year field experiment (2011, 2012 and 2013) was carried out in Ciudad Real (central Spain) to study the effects of wine-distillery waste compost application in a melon crop (Cucumis melo L.). Melon crop has been traditionally cultivated in this area with high inputs of water and fertilizers, but no antecedents of application of winery wastes are known. In a randomized complete block design, four treatments were compared: three compost doses consisted of 6.7 (D1), 13.3 (D2) and 20 t compost ha-1 (D3), and a control treatment without compost addition (D0). The soil was a shallow sandy-loam (Petrocalcic Palexeralfs) with a depth of 0.60 m and a discontinuous petrocalcic horizon between 0.60 and 0.70 m, slightly basic (pH 8.4), poor in organic matter (0.24%), rich in potassium (410 ppm) and with a medium level of phosphorus (22.1 ppm). During each growing period four harvests were carried out and total and marketable yield (fruits weighting <1 kg or visually rotten were not considered), fruit average weight and fruit number per plant were determined. At the end of the crop cycle, four plants per treatment were sampled and the nutrient content (N, P and K) was determined. Soil samplings (0-30 cm depth) were carried before the application of compost and at the end of each growing season and available N and P, as well as exchangeable K content were analyzed. With this information, an integrated analysis was carried out with the aim to evaluate the suitability of this compost as organic amendment.

Caracterización del hormigón en relación a la difusión de gases y su correlación con el radón

Radon gas (Rn) is a natural radioactive gas present in some soils and able to penetrate buildings through the building envelope in contact with the soil. Radon can accumulate within buildings and consequently be inhaled by their occupants. Because it is a radioactive gas, its disintegration process produces alpha particles that, in contact with the lung epithelia, can produce alterations potentially giving rise to cancer. Many international organizations related to health protection, such as WHO, confirm this causality. One way to avoid the accumulation of radon in buildings is to use the building envelope as a radon barrier. The extent to which concrete provides such a barrier is described by its radon diffusion coefficient (DRn), a parameter closely related to porosity (ɛ) and tortuosity factor (τ). The measurement of the radon diffusion coefficient presents challenges, due to the absence of standard procedures, the requirement to establish adequate airtightness in testing apparatus (referred to here as the diffusion cell), and due to the fact that measurement has to be carried out in an environment certified for use of radon calibrated sources. In addition to this calibrated radon sources are costly. The measurement of the diffusion coefficient for non-radioactive gas is less complex, but nevertheless retains a degree of difficulty due to the need to provide reliably airtight apparatus for all tests. Other parameters that can characterize and describe the process of gas transport through concrete include the permeability coefficient (K) and the electrical resistivity (ρe), both of which can be measured relatively easily with standardized procedure. The use of these parameters would simplify the characterization of concrete behaviour as a radon barrier. Although earlier studies exist, describing correlation among these parameters, there is, as has been observed in the literature, little common ground between the various research efforts. For precisely this reason, prior to any attempt to measure radon diffusion, it was deemed necessary to carry out further research in this area, as a foundation to the current work, to explore potential relationships among the following parameters: porosity-tortuosity, oxygen diffusion coefficient, permeability coefficient and resistivity. Permeability coefficient measurement (m2) presents a more straightforward challenge than diffusion coefficient measurement. Some authors identify a relationship between both coefficients, including Gaber (1988), who proposes: k= a•Dn Equation 1 Where: a=A/(8ΠD020), A = sample cross-section, D020 = diffusion coefficient in air (m2/s). Other studies (Klink et al. 1999, Gaber and Schlattner 1997, Gräf and Grube et al. 1986), experimentally relate both coefficients of different types of concrete confirming that this relationship exists, as represented by the simplified expression: k≈Dn Equation 2 In each particular study a different value for n was established, varying from 1.3 to 2.5, but this requires determination of a value for n in a more general way because these proposed models cannot estimate diffusion coefficient. If diffusion coefficient has to be measured to be able to establish n, these relationships are not interesting. The measurement of electric resistivity is easier than diffusion coefficient measurement. Correlation between the parameters can be established via Einstein´s law that relates movement of electrical charges to media conductivity according to the expression: D_e=k/ρ Equation 3 Where: De = diffusion coefficient (cm2/s), K = constant, ρ = electric resistivity (Ω•cm). The tortuosity factor is used to represent the uneven geometry of concrete pores, which are described as being not straight, but tortuous. This factor was first introduced in the literature to relate global porosity with fluid transport in a porous media, and can be formulated in a number of different ways. For example, it can take the form of equation 4 (Mason y Malinauskas), which combines molecular and Knudsen diffusion using the tortuosity factor: D=ε^τ (3/2r √(πM/8RT+1/D_0 ))^(-1) Equation 4 Where: r = medium radius obtained from MIP (µm), M = gas molecular mass, R = ideal gases constant, T = temperature (K), D0 = coefficient diffusion in the air (m2/s). Few studies provide any insight as to how to obtain the tortuosity factor. The work of Andrade (2012) is exceptional in this sense, as it outlines how the tortuosity factor can be deduced from pore size distribution (from MIP) from the equation: ∅_th=∅_0•ε^(-τ). Equation 5 Where: Øth = threshold diameter (µm), Ø0 = minimum diameter (µm), ɛ = global porosity, τ = tortuosity factor. Alternatively, the following equation may be used to obtain the tortuosity factor: DO2=D0*ɛτ Equation 6 Where: DO2 = oxygen diffusion coefficient obtained experimentally (m2/s), DO20 = oxygen diffusion coefficient in the air (m2/s). This equation has been inferred from Archie´s law ρ_e=〖a•ρ〗_0•ɛ^(-m) and from the Einstein law mentioned above, using the values of oxygen diffusion coefficient obtained experimentally. The principal objective of the current study was to establish correlations between the different parameters that characterize gas transport through concrete. The achievement of this goal will facilitate the assessment of the useful life of concrete, as well as open the door to the pro-active planning for the use of concrete as a radon barrier. Two further objectives were formulated within the current study: 1.- To develop a method for measurement of gas coefficient diffusion in concrete. 2.- To model an analytic estimation of radon diffusion coefficient from parameters related to concrete porosity and tortuosity factor. In order to assess the possible correlations, parameters have been measured using the standardized procedures or purpose-built in the laboratory for the study of equations 1, 2 y 3. To measure the gas diffusion coefficient, a diffusion cell was designed and manufactured, with the design evolving over several cycles of research, leading ultimately to a unit that is reliably air tight. The analytic estimation of the radon diffusion coefficient DRn in concrete is based on concrete global porosity (ɛ), whose values may be experimentally obtained from a mercury intrusion porosimetry test (MIP), and from its tortuosity factor (τ), derived using the relations expressed in equations 5 y 6. The conclusions of the study are: Several models based on regressions, for concrete with a relative humidity of 50%, have been proposed to obtain the diffusion coefficient following the equations K=Dn, K=a*Dn y D=n/ρe. The final of these three relations is the one with the determination coefficient closest to a value of 1: D=(19,997*LNɛ+59,354)/ρe Equation 7 The values of the obtained oxygen diffusion coefficient adjust quite well to those experimentally measured. The proposed method for the measurement of the gas coefficient diffusion is considered to be adequate. The values obtained for the oxygen diffusion coefficient are within the range of those proposed by the literature (10-7 a 10-8 m2/s), and are consistent with the other studied parameters. Tortuosity factors obtained using pore distribution and the expression Ø=Ø0*ɛ-τ are inferior to those from resistivity ρ=ρ0*ɛ-τ. The closest relationship to it is the one with porosity of pore diameter 1 µm (τ=2,07), being 7,21% inferior. Tortuosity factors obtained from the expression DO2=D0*ɛτ are similar to those from resistivity: for global tortuosity τ=2,26 and for the rest of porosities τ=0,7. Estimated radon diffusion coefficients are within the range of those consulted in literature (10-8 a 10-10 m2/s).ABSTRACT El gas radón (Rn) es un gas natural radioactivo presente en algunos terrenos que puede penetrar en los edificios a través de los cerramientos en contacto con el mismo. En los espacios interiores se puede acumular y ser inhalado por las personas. Al ser un gas radioactivo, en su proceso de desintegración emite partículas alfa que, al entrar en contacto con el epitelio pulmonar, pueden producir alteraciones del mismo causando cáncer. Muchos organismos internacionales relacionados con la protección de la salud, como es la OMS, confirman esta causalidad. Una de las formas de evitar que el radón penetre en los edificios es utilizando las propiedades de barrera frente al radón de su propia envolvente en contacto con el terreno. La principal característica del hormigón que confiere la propiedad de barrera frente al radón cuando conforma esta envolvente es su permeabilidad que se puede caracterizar mediante su coeficiente de difusión (DRn). El coeficiente de difusión de un gas en el hormigón es un parámetro que está muy relacionado con su porosidad (ɛ) y su tortuosidad (τ). La medida del coeficiente de difusión del radón resulta bastante complicada debido a que el procedimiento no está normalizado, a que es necesario asegurar una estanquidad a la celda de medida de la difusión y a que la medida tiene que ser realizada en un laboratorio cualificado para el uso de fuentes de radón calibradas, que además son muy caras. La medida del coeficiente de difusión de gases no radioactivos es menos compleja, pero sigue teniendo un alto grado de dificultad puesto que tampoco está normalizada, y se sigue teniendo el problema de lograr una estanqueidad adecuada de la celda de difusión. Otros parámetros que pueden caracterizar el proceso son el coeficiente de permeabilidad (K) y la resistividad eléctrica (ρe), que son más fáciles de determinar mediante ensayos que sí están normalizados. El uso de estos parámetros facilitaría la caracterización del hormigón como barrera frente al radón, pero aunque existen algunos estudios que proponen correlaciones entre estos parámetros, en general existe divergencias entre los investigadores, como se ha podido comprobar en la revisión bibliográfica realizada. Por ello, antes de tratar de medir la difusión del radón se ha considerado necesario realizar más estudios que puedan clarificar las posibles relaciones entre los parámetros: porosidad-tortuosidad, coeficiente de difusión del oxígeno, coeficiente de permeabilidad y resistividad. La medida del coeficiente de permeabilidad (m2) es más sencilla que el de difusión. Hay autores que relacionan el coeficiente de permeabilidad con el de difusión. Gaber (1988) propone la siguiente relación: k= a•Dn Ecuación 1 En donde: a=A/(8ΠD020), A = sección de la muestra, D020 = coeficiente de difusión en el aire (m2/s). Otros estudios (Klink et al. 1999, Gaber y Schlattner 1997, Gräf y Grube et al. 1986) relacionan de forma experimental los coeficientes de difusión de radón y de permeabilidad de distintos hormigones confirmando que existe una relación entre ambos parámetros, utilizando la expresión simplificada: k≈Dn Ecuación 2 En cada estudio concreto se han encontrado distintos valores para n que van desde 1,3 a 2,5 lo que lleva a la necesidad de determinar n porque no hay métodos que eviten la determinación del coeficiente de difusión. Si se mide la difusión ya deja de ser de interés la medida indirecta a través de la permeabilidad. La medida de la resistividad eléctrica es muchísimo más sencilla que la de la difusión. La relación entre ambos parámetros se puede establecer a través de una de las leyes de Einstein que relaciona el movimiento de cargas eléctricas con la conductividad del medio según la siguiente expresión: D_e=k/ρ_e Ecuación 3 En donde: De = coeficiente de difusión (cm2/s), K = constante, ρe = resistividad eléctrica (Ω•cm). El factor de tortuosidad es un factor de forma que representa la irregular geometría de los poros del hormigón, al no ser rectos sino tener una forma tortuosa. Este factor se introduce en la literatura para relacionar la porosidad total con el transporte de un fluido en un medio poroso y se puede formular de distintas formas. Por ejemplo se destaca la ecuación 4 (Mason y Malinauskas) que combina la difusión molecular y la de Knudsen utilizando el factor de tortuosidad: D=ε^τ (3/2r √(πM/8RT+1/D_0 ))^(-1) Ecuación 4 En donde: r = radio medio obtenido del MIP (µm), M = peso molecular del gas, R = constante de los gases ideales, T = temperatura (K), D0 = coeficiente de difusión de un gas en el aire (m2/s). No hay muchos estudios que proporcionen una forma de obtener este factor de tortuosidad. Destaca el estudio de Andrade (2012) en el que deduce el factor de tortuosidad de la distribución del tamaño de poros (curva de porosidad por intrusión de mercurio) a partir de la ecuación: ∅_th=∅_0•ε^(-τ) Ecuación 5 En donde: Øth = diámetro umbral (µm), Ø0 = diámetro mínimo (µm), ɛ = porosidad global, τ = factor de tortuosidad. Por otro lado, se podría utilizar también para obtener el factor de tortuosidad la relación: DO2=D0*-τ Ecuación 6 En donde: DO2 = coeficiente de difusión del oxígeno experimental (m2/s), DO20 = coeficiente de difusión del oxígeno en el aire (m2/s). Esta ecuación está inferida de la ley de Archie ρ_e=〖a•ρ〗_0•ɛ^(-m) y la de Einstein mencionada anteriormente, utilizando valores del coeficiente de difusión del oxígeno DO2 obtenidos experimentalmente. El objetivo fundamental de la tesis es encontrar correlaciones entre los distintos parámetros que caracterizan el transporte de gases a través del hormigón. La consecución de este objetivo facilitará la evaluación de la vida útil del hormigón así como otras posibilidades, como la evaluación del hormigón como elemento que pueda ser utilizado en la construcción de nuevos edificios como barrera frente al gas radón presente en el terreno. Se plantean también los siguientes objetivos parciales en la tesis: 1.- Elaborar una metodología para la medida del coeficiente de difusión de los gases en el hormigón. 2.- Plantear una estimación analítica del coeficiente de difusión del radón a partir de parámetros relacionados con su porosidad y su factor de tortuosidad. Para el estudio de las correlaciones posibles, se han medido los parámetros con los procedimientos normalizados o puestos a punto en el propio Instituto, y se han estudiado las reflejadas en las ecuaciones 1, 2 y 3. Para la medida del coeficiente de difusión de gases se ha fabricado una celda que ha exigido una gran variedad de detalles experimentales con el fin de hacerla estanca. Para la estimación analítica del coeficiente de difusión del radón DRn en el hormigón se ha partido de su porosidad global (ɛ), que se obtiene experimentalmente del ensayo de porosimetría por intrusión de mercurio (MIP), y de su factor de tortuosidad (τ), que se ha obtenido a partir de las relaciones reflejadas en las ecuaciones 5 y 6. Las principales conclusiones obtenidas son las siguientes: Se proponen modelos basados en regresiones, para un acondicionamiento con humedad relativa de 50%, para obtener el coeficiente de difusión del oxígeno según las relaciones: K=Dn, K=a*Dn y D=n/ρe. La propuesta para esta última relación es la que tiene un mejor ajuste con R2=0,999: D=(19,997*LNɛ+59,354)/ρe Ecuación 7 Los valores del coeficiente de difusión del oxígeno así estimados se ajustan a los obtenidos experimentalmente. Se considera adecuado el método propuesto de medida del coeficiente de difusión para gases. Los resultados obtenidos para el coeficiente de difusión del oxígeno se encuentran dentro del rango de los consultados en la literatura (10-7 a 10-8 m2/s) y son coherentes con el resto de parámetros estudiados. Los resultados de los factores de tortuosidad obtenidos de la relación Ø=Ø0*ɛ-τ son inferiores a la de la resistividad (ρ=ρ0*ɛ-τ). La relación que más se ajusta a ésta, siendo un 7,21% inferior, es la de la porosidad correspondiente al diámetro 1 µm con τ=2,07. Los resultados de los factores de tortuosidad obtenidos de la relación DO2=D0*ɛτ son similares a la de la resistividad: para la porosidad global τ=2,26 y para el resto de porosidades τ=0,7. Los coeficientes de difusión de radón estimados mediante estos factores de tortuosidad están dentro del rango de los consultados en la literatura (10-8 a 10-10 m2/s).

Simple mechanochemistry describes the dynamics of kinesin molecules

Recently, Block and coworkers [Visscher, K., Schnitzer, M. J., & Block, S. M. (1999) Nature (London) 400, 184–189 and Schnitzer, M. J., Visscher, K. & Block, S. M. (2000) Nat. Cell Biol. 2, 718–723] have reported extensive observations of individual kinesin molecules moving along microtubules in vitro under controlled loads, F = 1 to 8 pN, with [ATP] = 1 μM to 2 mM. Their measurements of velocity, V, randomness, r, stalling force, and mean run length, L, reveal a need for improved theoretical understanding. We show, presenting explicit formulae that provide a quantitative basis for comparing distinct molecular motors, that their data are satisfactorily described by simple, discrete-state, sequential stochastic models. The simplest (N = 2)-state model with fixed load-distribution factors and kinetic rate constants concordant with stopped-flow experiments, accounts for the global (V, F, L, [ATP]) interdependence and, further, matches relative acceleration observed under assisting loads. The randomness, r(F,[ATP]), is accounted for by a waiting-time distribution, ψ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{1}^{+}}}\end{equation*}\end{document}(t), [for the transition(s) following ATP binding] with a width parameter ν ≡ 〈t〉2/〈(Δt)2〉≃2.5, indicative of a dispersive stroke of mechanicity ≃0.6 or of a few (≳ν − 1) further, kinetically coupled states: indeed, N = 4 (but not N = 3) models do well. The analysis reveals: (i) a substep of d0 = 1.8–2.1 nm on ATP binding (consistent with structurally based suggestions); (ii) comparable load dependence for ATP binding and unbinding; (iii) a strong load dependence for reverse hydrolysis and subsequent reverse rates; and (iv) a large (≳50-fold) increase in detachment rate, with a marked load dependence, following ATP binding.

Desenvolvimento de protocolos para IATF com 7 dias de permanência do CIDR® em fêmeas Nelore

O objetivo do experimento I foi avaliar a redução do tempo de permanência do dispositivo de P4 de 9 para 7 dias sob parâmetros reprodutivos de vacas Nelore. Foram utilizadas 674 vacas lactantes entre 40-60 dias pós parto que receberam no início do protocolo (d0) BE + CIDR. No momento da retirada do CIDR foi administrado PGF2 α, ECP e eCG. A IATF ocorreu 55 e 48 horas após a retirada do dispositivo nos tratamentos 7d-CIDR e 9d-CIDR, respectivamente. Dez dias após a IA foi realizada colheita de sangue para dosagem de P4 sérica e confirmação da ovulação. Vacas tratadas com 7d-CIDR apresentaram menor (p < 0,01) folículo ovulatório em relação ao 9d-CIDR. No entanto, a concentração de P4 pós-IA, taxas de ovulação, detecção de estro e prenhez não foram influenciadas pelo tempo de permanência do CIDR. Assim, o uso do CIDR por 7 dias promoveu desempenho reprodutivo semelhante em vacas Nelore comparado ao protocolo com 9 dias. O experimento II teve o objetivo de avaliar os efeitos da reutilização do CIDR por até 35 dias de uso em vacas e 42 dias em novilhas Nelore. Utilizou-se 749 vacas lactantes 40-60 dias pós parto e 92 novilhas púberes. No d0 os animais receberam BE + CIDR novo (CIDR1) ou previamente usado por 7 (CIDR2), 14 (CIDR3), 21 (CIDR4), 28 (CIDR5) e 35 (CIDR6) dias. No momento da retirada do CIDR (d7) foi administrado PGF2 α, ECP, eCG e exame de US para mensuração do maior folículo (FD), além de colheita de sangue para dosagem de P4. A IATF ocorreu 55 horas após a retirada do dispositivo. O diâmetro do FD foi maior (p < 0,01) de acordo com o maior número de usos do CIDR nas vacas, a concentração de P4 reduziu nos CIDRs reutilizados porém se mantiveram acima de 1,5 ng/ml e a taxa de prenhez não foi afetada pela reutilização do dispositivo por até 5 vezes em vacas e o sexto uso em novilhas. O protocolo com 7 dias de permanência permite a reutilização do CIDR por até 6 vezes mantendo a mesma eficiência reprodutiva. No experimento III o objetivo foi avaliar se a aplicação do eCG dois dias antes da retirada do dispositivo aumenta o tamanho do FO, CL e taxa de prenhez. Foram utilizadas 681 vacas lactantes 40-60 dias pós parto e 182 novilhas púberes. Os animais foram distribuídos em dois tratamentos com aplicação de eCG no quinto (5d-eCG) ou sétimo dia (7d-eCG). No d0, os animais receberam BE + CIDR e no dia 7 o CIDR foi retirado e administrado PGF2 α e ECP. Dez dias após a IA foi realizada US para mensuração do CL e colheita de sangue para dosagem de P4. A IATF ocorreu 55 horas após a retirada do dispositivo. O tratamento 5d-eCG aumentou (p < 0,01) o FO nas vacas em relação ao grupo 7deCG e o mesmo ocorreu nas novilhas. Em vacas, a concentração de P4 pós IA foi mais alta (p = 0,04) no 5d-eCG. Em novilhas o diâmetro do CL pós-IA foi maior (p < 0,01) no 5d-eCG. No entanto, a antecipação da aplicação do eCG foi eficiente em aumentar o folículo ovulatório no momento da IATF, mas não aumentou a taxa de prenhez

Information Guide: ინფორმაცია ევროკავშირზე ქართული წყაროებიდან.

No abstract.

Information Guide: Информация о Европейском союзе из Русскийх источников

No abstract.

Frequência de microrganismos em conteúdo vulvovaginal de vacas tratadas com dispositivos intravaginais de progesterona

The dissertation was divided in two studies. With the first, aimed to evaluate the occurrence of microorganisms present in the vulvovaginal region of cows that received intravaginal progesterone devices during the fixed-time artificial insemination (FTAI) programs, and correlate the results with pregnancy rates. Samples were collected from vulvovaginal region of 30 beef cows Guzerá and 30 crossbred dairy cows, and also intravaginal devices, randomly. Of the 120 samples of cows, 60 corresponded to the collections of the period prior to the introduction device (D0) and 60 to the subsequent withdrawal of it (D9); it yielded 100% of bacterial growth, whereas, in most samples, it was found more than one isolated. In D0, the most frequent agent was Escherichia coli (52%), and in D9, Proteus spp and E. coli were the most frequent (32% and 28%, respectively). Regarding intravaginal progesterone devices, in D0 were isolated 37 microorganisms, being predominant those of the genus Bacillus (35%); in D9, 41 colony forming units (CFU) were isolated, of which 36.6% corresponded to Proteus spp. For the analysis of the antimicrobial profile, susceptibility testing was performed by diffusion agar disk, and cows that did not became pregnant after FTAI program were selected, as a future treatment. There resistance 100% to penicillin, and sensitivity, approximately, 90% to gentamicin, both isolates obtained from samples of beef cows and obtained of dairy cows. Regarding pregnancy rate, the 30 beef cows, 11 were diagnosed pregnant (36.7%), 4 (36.4%) treated with reused devices and 7 (63.6%) with new devices, which showed more effective. Of the 30 dairy cows, 15 were pregnant (50%), 8 (53.3%) were implanted with reused devices and 7 (46.7%) with new devices, with no significant differences in pregnancy rates. Because it is a research, females were chosen at random, and factors such as body condition, nutritional management and health weren't priority. With the second study, aimed to analyze the similarity between strains, conducted by technical Random Amplified Polymorphic DNA (RAPD -PCR). Presence of E. coli and the absence of pregnancy were selection criteria used. From the results, it was observed that most of the isolates wasn't phylogenetically similar, since they showed lower than 85% similarity. The study stressed the importance of E. coli in vulvovaginal microbiota of cows and the presence of phenotypic and genotypic characters of this bacterium on possible reproductive problems.