The effect of surface tension on the growth of Lactobacillus bulgaricus and Lactobacillus acidophilus.

1925 ◽  
Vol 22 (6) ◽  
pp. 337-338 ◽  
Author(s):  
W. R. Albus ◽  
G. E. Holm
2019 ◽  
Vol 29 (7) ◽  
pp. 629-654
Author(s):  
Zehao Feng ◽  
Shangqing Tong ◽  
Chenglong Tang ◽  
Cheng Zhan ◽  
Keiya Nishida ◽  
...  

2018 ◽  
Author(s):  
Timothy Duignan ◽  
Marcel Baer ◽  
Christopher Mundy

<div> <p> </p><div> <div> <div> <p>The surface tension of dilute salt water is a fundamental property that is crucial to understanding the complexity of many aqueous phase processes. Small ions are known to be repelled from the air-water surface leading to an increase in the surface tension in accordance with the Gibbs adsorption isotherm. The Jones-Ray effect refers to the observation that at extremely low salt concentration the surface tension decreases in apparent contradiction with thermodynamics. Determining the mechanism that is responsible for this Jones-Ray effect is important for theoretically predicting the distribution of ions near surfaces. Here we show that this surface tension decrease can be explained by surfactant impurities in water that create a substantial negative electrostatic potential at the air-water interface. This potential strongly attracts positive cations in water to the interface lowering the surface tension and thus explaining the signature of the Jones-Ray effect. At higher salt concentrations, this electrostatic potential is screened by the added salt reducing the magnitude of this effect. The effect of surface curvature on this behavior is also examined and the implications for unexplained bubble phenomena is discussed. This work suggests that the purity standards for water may be inadequate and that the interactions between ions with background impurities are important to incorporate into our understanding of the driving forces that give rise to the speciation of ions at interfaces. </p> </div> </div> </div> </div>


2009 ◽  
Vol 39 (9) ◽  
pp. 2595-2600 ◽  
Author(s):  
Larissa de Lima Alves ◽  
Neila Silvia Pereira dos Santos Richards ◽  
Larissa Vargas Becker ◽  
Diego Fontana de Andrade ◽  
Liana Inês Guidolin Milani ◽  
...  

O leite de cabra é recomendado para pessoas intolerantes ao leite de vaca e/ou portadoras de desordens gastrintestinais. frozen yogurt elaborado a partir de iogurte de leite de cabra foi acrescido de 1% de prebiótico (inulina), 0,25% de cultura starter (Streptococcus thermophilus e Lactobacillus bulgaricus) e 0,25% de cultura probiótica (Bifidobacterium animalis e Lactobacillus acidophilus) para verificar seu potencial probiótico (após sete e 120 dias de armazenamento), sua qualidade físico-química e sua aceitação sensorial. Durante a estocagem, houve redução de células viáveis da flora microbiana, principalmente dos probióticos. Ainda assim, o produto apresenta potencialidade probiótica pela soma de B. animalis e L. acidophilus atingir o mínimo desejável até o fim do armazenamento. Os valores de extrato seco total (26,6±0,2%), proteína (3,0±0,2), gordura (2,6±0,1%), pH (5,5±0,01) e ácido láctico (0,2±0,01%) encontram-se semelhantes aos relatados em outros trabalhos para o mesmo produto. A avaliação sensorial foi realizada por 50 provadores não treinados em teste com escala hedônica de sete níveis e intenção de compra. O produto recebeu bons escores para aparência global, cor, aroma e sabor; já textura e sabor residual obtiveram menores índices de aceitação. Na intenção de compra, 61% dos avaliadores declararam que comprariam o produto, contra 39% que não comprariam. Nessas condições, demonstra-se a viabilidade de elaboração de frozen yogurt de leite caprino acrescido de pre- e probióticos.


Author(s):  
Christopher C. Green ◽  
Christopher J. Lustri ◽  
Scott W. McCue

New numerical solutions to the so-called selection problem for one and two steadily translating bubbles in an unbounded Hele-Shaw cell are presented. Our approach relies on conformal mapping which, for the two-bubble problem, involves the Schottky-Klein prime function associated with an annulus. We show that a countably infinite number of solutions exist for each fixed value of dimensionless surface tension, with the bubble shapes becoming more exotic as the solution branch number increases. Our numerical results suggest that a single solution is selected in the limit that surface tension vanishes, with the scaling between the bubble velocity and surface tension being different to the well-studied problems for a bubble or a finger propagating in a channel geometry.


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