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2022 ◽  
Vol 293 ◽  
pp. 110708
Author(s):  
Yanli Zheng ◽  
Xiaoyu Jia ◽  
Yalin Ran ◽  
Meijun Du ◽  
Zhiyong Zhao ◽  
...  

2022 ◽  
Author(s):  
Svetlana Aleksandrovna Evdokimova ◽  
Vera Stanislavovna Nokhaeva ◽  
Boris Alekseevich Karetkin ◽  
Irina Vasilievna Shakir ◽  
Viktor Ivanovich Panfilov

In this study, the ability of a probioticstrain (BifidobacteriumadolescentisATCC 15703) to inhibit the growth of the common food contaminantBacilluscereusATCC 9634was studied, both individually and as part of a synbiotic with FOS during batch or continuous fermentation (flow fermentation). The conditions of the flow fermentation corresponded to the parameters of the human large intestine: maintaining a pH of 6.8; anaerobiosis; and a medium flow rate of 0.04 h−1. Bifidobacteria and bacilli were co-cultivated on a prebiotic carbohydrate substrate (10 g/L) and the prebiotic was replaced with glucose (10 g/L).The results of the batch and flow fermentation were compared.The synbiotic efficacy of the probioticBif. adolescentisand the prebiotic FOSagainst the common food contaminantBac. cereuswas shown for all conditions. Fermentation of a pure culture of bifidobacteria with varying prebiotic concentrations (2, 5, 10, 15 and 20 g/L) was carried out to study the state of dynamic balance. It was demonstrated that 48 hours is enough to achieve stable dynamic balance.Prebiotics were co-cultivated with varying carbohydrate concentrations of 5, 10, and 15 g/L.The results showed that increasing the prebiotic concentration increased the duration of the lag-phase and reduced the final number of bacilli. Keywords: probiotics, prebiotics, synbiotics, gastrointestinal tract modeling, antagonism, co-culture fermentation


2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Johannes Schmidt ◽  
Anna Martin ◽  
Christin Wenzel ◽  
Jonas Weber ◽  
Steffen Wirth ◽  
...  

Abstract Background Pursed-lips breathing (PLB) is a technique to attenuate small airway collapse by regulating the expiratory flow. During mandatory ventilation, flow-controlled expiration (FLEX), which mimics the expiratory flow course of PLB utilizing a digital system for measurement and control, was shown to exert lung protective effects. However, PLB requires a patient’s participation and coordinated muscular effort and FLEX requires a complex technical setup. Here, we present an adjustable flow regulator to mimic PLB and FLEX, respectively, without the need of a patient’s participation, or a complex technical device. Methods Our study consisted of two parts: First, in a lung model which was ventilated with standard settings (tidal volume 500 ml, respiratory rate 12 min−1, positive end-expiratory pressure (PEEP) 5 cmH2O), the possible reduction of the maximal expiratory flow by utilizing the flow regulator was assessed. Second, with spontaneously breathing healthy volunteers, the short-term effects of medium and strong expiratory flow reduction on airway pressure, the change of end-expiratory lung volume (EELV), and breathing discomfort was investigated. Results In the lung model experiments, expiratory flow could be reduced from − 899 ± 9 ml·s−1 down to − 328 ± 25 ml·s−1. Thereby, inspiratory variables and PEEP were unaffected. In the volunteers, the maximal expiratory flow of − 574 ± 131 ml·s−1 under baseline conditions was reduced to − 395 ± 71 ml·s−1 for medium flow regulation and to − 266 ± 58 ml·s−1 for strong flow regulation, respectively (p < 0.001). Accordingly, mean airway pressure increased from 0.6 ± 0.1 cmH2O to 2.9 ± 0.4 cmH2O with medium flow regulation and to 5.4 ± 2.4 cmH2O with strong flow regulation, respectively (p < 0.001). The EELV increased from baseline by 31 ± 458 ml for medium flow regulation and 320 ± 681 ml for strong flow regulation (p = 0.033). The participants rated breathing with the flow regulator as moderately uncomfortable, but none rated breathing with the flow regulator as intolerable. Conclusions The flow regulator represents an adjustable device for application of a self-regulated expiratory resistive load, representing an alternative for PLB and FLEX. Future applications in spontaneously breathing patients and patients with mandatory ventilation alike may reveal potential benefits. Trial registration: DRKS00015296, registered on 20th August, 2018; URL: https://www.drks.de/drks_web/setLocale_EN.do.


2021 ◽  
Author(s):  
Thomas Riva ◽  
Robert Greif ◽  
Heiko Kaiser ◽  
Thomas Riedel ◽  
Markus Huber ◽  
...  

Background Anesthesia studies using high-flow, humidified, heated oxygen delivered via nasal cannulas at flow rates of more than 50 l · min–1 postulated a ventilatory effect because carbon dioxide increased at lower levels as reported earlier. This study investigated the increase of arterial partial pressure of carbon dioxide between different flow rates of 100% oxygen in elective anesthetized and paralyzed surgical adults before intubation. Methods After preoxygenation and standardized anesthesia induction with nondepolarizing neuromuscular blockade, all patients received 100% oxygen (via high-flow nasal oxygenation system or circuit of the anesthesia machine), and continuous jaw thrust/laryngoscopy was applied throughout the 15-min period. In this single-center noninferiority trial, 25 patients each, were randomized to five groups: (1) minimal flow: 0.25 l · min–1, endotracheal tube; (2) low flow: 2 l · min–1, continuous jaw thrust; (3) medium flow: 10 l · min–1, continuous jaw thrust; (4) high flow: 70 l · min–1, continuous jaw thrust; and (5) control: 70 l · min–1, continuous laryngoscopy. Immediately after anesthesia induction, the 15-min apnea period started with oxygen delivered according to the randomized flow rate. Serial arterial blood gas analyses were drawn every 2 min. The study was terminated if either oxygen saturation measured by pulse oximetry was less than 92%, transcutaneous carbon dioxide was greater than 100 mmHg, pH was less than 7.1, potassium level was greater than 6 mmol · l–1, or apnea time was 15 min. The primary outcome was the linear rate of mean increase of arterial carbon dioxide during the 15-min apnea period computed from linear regressions. Results In total, 125 patients completed the study. Noninferiority with a predefined noninferiority margin of 0.3 mmHg · min–1 could be declared for all treatments with the following mean and 95% CI for the mean differences in the linear rate of arterial partial pressure of carbon dioxide with associated P values regarding noninferiority: high flow versus control, –0.0 mmHg · min–1 (–0.3, 0.3 mmHg · min–1, P = 0.030); medium flow versus control, –0.1 mmHg · min–1 (–0.4, 0.2 mmHg · min–1, P = 0.002); low flow versus control, –0.1 mmHg · min–1 (–0.4, 0.2 mmHg · min–1, P = 0.003); and minimal flow versus control, –0.1 mmHg · min–1 (–0.4, 0.2 mmHg · min–1, P = 0.004). Conclusions Widely differing flow rates of humidified 100% oxygen during apnea resulted in comparable increases of arterial partial pressure of carbon dioxide, which does not support an additional ventilatory effect of high-flow nasal oxygenation. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New


Author(s):  
O. Aleksakhin ◽  
S. Yena ◽  
O. Hordiienko ◽  
V. Novikov ◽  
D. Tsemokh

The comparison of heat losses by pipelines of an extensive residential neighborhood heating system for two options of the distribution network was carried out for a residential neighborhood in Kharkov. The proposed configuration of the heating network differs from the existing ("basic") one in using of the law of heating medium flow rate variation along the heat pipe length. This law takes into account increased flow rate of heating water through branches at the initial sections of the pipeline. The actual flow rate distribution is approximated by a step function. The difference in the laws of flow rate variation is taken into account by the exponent value. The calculation of heat losses was carried out for underground pipelining in non-accessible tunnels. The temperature of heat line water is taken to be the corresponding to the design outdoor air temperature for heating according to the temperature schedule of the heating network. Specific heat losses by pipelines in heat network sections are considered to be at the standard level for non-accessible tunnels. The soil temperature at the depth of the heat pipe axis is taken equal to 5°C. Heat losses by the structural elements of the heat network are taken into account by a factor of 1.15. The variation of the flow rate and temperature of network water in rated pipeline sections is considered in the analysis.  The water flow rate at the sections was found based on the design thermal loads of connected buildings. It is shown that when choosing the configuration of the distribution network of the heating system of a group of buildings, preference should be given to the option with a lower value of the exponent in the equation for heating medium flow rate variation along the length of the main line of the network. For extensive heating networks, this can be achieved by connecting as many buildings as possible to the heating network sections close to a heat supply station. An increase in the network water flow rate through the branches at the initial sections of the pipeline ensures a decrease in heat losses by the network pipelines. For the considered part of a residential neighborhood, the decrease in heat loss at the design outdoor air temperature for heating is 5.5 %.


Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6903
Author(s):  
Peng Wang ◽  
Jinling Lu ◽  
Qingsen Cai ◽  
Senlin Chen ◽  
Xingqi Luo

The circulating cooling water system is widely used in various industrial production fields, and its operating cost largely depends on external factors, such as ambient temperature and working medium flow. Considering the relative elevation of the heat exchanger, this study establishes a total system operation cost analysis and optimization model based on the superstructure method. The model uses ambient dry bulb temperature, ambient wet bulb temperature, and working medium flow as random variables. Water supply temperature is adopted as the decision variable, and the minimum operating cost of the system is used as the objective function. An analysis of the effect of the three random variables on the operation cost shows that the effect of ambient dry bulb temperature on the operation cost is negligible, and the effect of ambient wet bulb temperature and working medium flow on the operation cost is significant. In addition, a control equation of water supply temperature is established to determine the “near optimal” operation, which is based on the correlation among ambient wet bulb temperature, working medium flow, and optimal water supply temperature. Then, the method is applied to a case system. The operating cost of the system is reduced by 22–31% at different times during the sampling day.


2021 ◽  
Vol 210 ◽  
pp. 112393
Author(s):  
Young-Pil Choi ◽  
In-Jee Jeong

Author(s):  
E. A. Fedyanov ◽  
V. A. Saninsky ◽  
N. A. Ushakov

The method for calculating the parameters of the cylindrical throttling elements of the tipping teeth of a multi-toothed mandrel has been performed, which makes it possible to provide the required volume and distribution of the working medium flow supplied to the mandrel in the process of processing deep holes of long cylinders and to substantiate the division of the total flow into several different streams that provide throttling of the lubricating-cooling liquid (Coolant) when used in a lubricating and cooling technological environment (SOTS). It is assumed that the processing is carried out on the principles of combining the processes of vortex milling and surface plastic deformation (SPD) by the methods and method of helical interpolation presented in the description of the monograph. The research results based on the developed methodology for calculating the flow rate of the working medium in cylindrical throttling elements allows for further improvement of existing methods for processing deep holes, including improving the quality of high-precision precision pipes.


2021 ◽  
Vol 410 ◽  
pp. 21-27
Author(s):  
Andrey A. Gruzdev ◽  
Yuriy A. Morgunov ◽  
Boris P. Saushkin

This paper considers some theoretical provisions on the impact ultrasonic mechanical vibrations have on the throughput of an electroerosive piercing of small-diameter holes. The approximate estimates confirm the hypothesis that the cumulative jets mechanism makes the greatest contribution to the intensification of a multiphase medium flow in the interelectrode gap. A model is proposed for a periodic localization of the cavitation region in the bottom part of the annular side gap. It allows explaining the occurrence of a multiphase medium flow during hole processing.


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