Showing items 1 - 6 of 6

Your selections:

Drying kinetics and survival studies of dairy fermentation bacteria in convective air drying environment using single droplet drying

- Ghandi, Amir, Powell, Ian, Chen, Xiao Dong, Adhikari, Benu

  • Authors: Ghandi, Amir , Powell, Ian , Chen, Xiao Dong , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 110, no. 3 (2012), p. 405-417
  • Full Text:
  • Reviewed:
  • Description: The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45-95°C) at a constant air velocity (0.5 m/s) and within 2.4-11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (≥65°C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (≤55°C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3 kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8 kJ/mol) within the medium temperature of 45-95°C. © 2012 Elsevier Ltd. All rights reserved.

Musculoskeletal stiffness during hopping and running does not change following downhill backwards walking

- Joseph, Corey, Bradshaw, Elizabeth, Kemp, Justin, Clark, Ross

  • Authors: Joseph, Corey , Bradshaw, Elizabeth , Kemp, Justin , Clark, Ross
  • Date: 2014
  • Type: Text , Journal article
  • Relation: Sports Biomechanics Vol. 13, no. 3 (2014), p. 241-258
  • Full Text:
  • Reviewed:
  • Description: Eccentric contractions that provide spring energy can also cause muscle damage. The aim of this study was to explore leg and vertical stiffness following muscle damage induced by an eccentric exercise protocol. Twenty active males completed 60 minutes of backward-walking on a treadmill at 0.67 m/s and a gradient of − 8.5° to induce muscle damage. Tests were performed immediately before; immediately post; and 24, 48, and 168 hours post eccentric exercise. Tests included running at 3.35 m/s and hopping at 2.2 Hz using single- and double-legged actions. Leg and vertical stiffness were measured from kinetic and kinematic data, and electromyography (EMG) of five muscles of the preferred limb were recorded during hopping. Increases in pain scores (over 37%) occurred post-exercise and 24 and 48 hours later (p < 0.001). A 7% decrease in maximal voluntary contraction occurred immediately post-exercise (p = 0.019). Changes in knee kinematics during single-legged hopping were observed 168 hours post (p < 0.05). No significant changes were observed in EMG, creatine kinase activity, leg, or vertical stiffness. Results indicate that knee mechanics may be altered to maintain consistent levels of leg and vertical stiffness when eccentric exercise-induced muscle damage is present in the lower legs. © 2014 Taylor & Francis.

The inactivation kinetics of polyphenol oxidase in mushroom (Agaricus bisporus) during thermal and thermosonic treatments

- Cheng, X., Zhang, Min, Adhikari, Benu

  • Authors: Cheng, X. , Zhang, Min , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Ultrasonics Sonochemistry Vol. 20, no. 2 (2013), p. 674-679
  • Full Text: false
  • Reviewed:
  • Description: The effect of thermal and thermosonic treatments on the inactivation kinetics of polyphenol oxidase (PPO) in mushroom (Agaricus bisporus) was studied in 55-75°C temperature range. In both the processes, the inactivation kinetics of PPO followed a first-order kinetics (R2 = 0.941-0.989). The D values during thermal inactivation varied from 112 ± 8.4 min to 1.2 ± 0.07 min while they varied from 57.8 ± 6.1 min to 0.88 ± 0.05 min during thermosonic inactivation at the same temperature range. The activation energy during thermal inactivation was found to be 214 ± 17 kJ/mol, while it was 183 ± 32 kJ/mol during thermosonic inactivation. The inactivating effect of combined ultrasound and heat was found to synergistically enhance the inactivation kinetics of PPO. The D values of PPO decreased by 1.3-3 times during thermosonic inactivation compared to the D values of PPO during thermal inactivation at the temperature range. Therefore, thermosonication can be further developed as an alternative to "hot break" process of mushroom. © 2012 Elsevier B.V. All rights reserved.
  • Description: 2003010582

Thermodynamics and kinetics of the FoF1-ATPase: application of the probability isotherm

- Chapman, Brian, Loiselle, Denis

Decoupled modeling of gene regulatory networks using Michaelis-Menten kinetics

- Youseph, Ahammed, Chetty, Madhu, Karmakar, Gour

  • Authors: Youseph, Ahammed , Chetty, Madhu , Karmakar, Gour
  • Date: 2015
  • Type: Text , Conference proceedings
  • Full Text: false
  • Description: A set of genes and their regulatory interactions are represented in a gene regulatory network (GRN). Since GRNs play a major role in maintaining the cellular activities, inferring these networks is significant for understanding biological processes. Among the models available for GRN reconstruction, our recently developed nonlinear model [1] using Michaelis-Menten kinetics is considered to be more biologically relevant. However, the model remains coupled in the current form making the process computationally expensive, especially for large GRNs. In this paper, we enhance the existing model leading to a decoupled form which not only speeds up the computation, but also makes the model more realistic by representing the strength of each regulatory arc by a distinct Michaelis-Menten constant. The parameter estimation is carried out using differential evolution algorithm. The model is validated by inferring two synthetic networks. Results show that while the accuracy of reconstruction is similar to the coupled model, they are achieved at a faster speed. © Springer International Publishing Switzerland 2015.

Jump-landing mechanics in patellar tendinopathy in elite youth basketballers

- Harris, Meaghan, Schultz, Adrian, Drew, Michael, Rio, Ebonie, Charlton, Paula, Edwards, Suzi

  • Authors: Harris, Meaghan , Schultz, Adrian , Drew, Michael , Rio, Ebonie , Charlton, Paula , Edwards, Suzi
  • Date: 2020
  • Type: Text , Journal article
  • Relation: Scandinavian Journal of Medicine & Science in Sports Vol. 30, no. 3 (Mar 2020), p. 540-548
  • Full Text: false
  • Reviewed:
  • Description: Patellar tendinopathy (PT) is a leading cause of morbidity in jump-landing athletes. Landing mechanics are identified as a factor associated with PT and/or patellar tendon abnormality. This study aimed to identify key jump-landing variables associated with PT. Thirty-six junior elite basketball players (men n = 18, women n = 18) were recruited from a Basketball Australia development camp. Three-dimensional (3D) kinematic and ground reaction force (GRF) data during a stop-jump task were collected as well as ultrasound scans of the patellar tendons and recall history of training load data. Mixed-model factorial analyses of variance were used to determine any significant between-group differences. Of the 23 participants included for statistical analyses, 11 had normal bilateral patellar tendons (controls) and eight reported PT (currently symptomatic); however, the four participants categorized as asymptomatic with patellar tendon abnormality on diagnostic imaging were excluded from statistical analyses due to their small sample size. Athletes with PT displayed a similar knee flexion angle at initial foot-ground contact (IC) and hip extension strategy during a stop-jump horizontal landing. Despite a similar kinematic technique, athletes with PT utilized a strategy of a longer stance duration phase from IC to peak force. This strategy did not lead to those athletes with PT decreasing their peak vertical GRF nor patellar tendon force during landing but enabled these athletes to land with a lower rate of loading (control 59.2 +/- 39.3 vs. PT 29.4 +/- 33.7 BW.s-1). Athletes with PT still reported significantly reduced training volume (control 4.9 +/- 1.8 vs PT 1.8 +/- 1.1 sessions/wk; total training time/wk control 2.4 +/- 1.0 vs PT 1.4 +/- 1.1 h/wk).
  • 1