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In this study, an in situ 7.5 L ultrasonic fermentation tank was used to culture Saccharomyces cerevisiae at 30°C for 36 hr to explore the effects of low intensity ultrasound on the production of glutathione (GSH). Ultrasonic conditions of 28 kHz frequency, 28 W/L power density for fermentation time of 0–12 hr, 280 W/L power density for fermentation time of 12–36 hr, 3 s of interval and fixed frequency mode were used for the set‐up and a nonsonicated set‐up served as the control for the experiment. Results showed that ultrasound treatment increased total GSH production by 15.60% from a maximum value of 45.52 mg/L in the control to a maximum value of 52.62 mg/L in the sonicated sample. Also, intracellular and extracellular GSH productions in the sonicated sample increased by 5.60% and 42.92% respectively. Regular detection of the changes of biomass yield, residual sugar, dissolved oxygen and pH showed that sonication resulted in biomass increased by 7.25%, glucose consumption rate increased by 53.08% and dissolved oxygen content decreased by 41.67%. The biomass models of sonication and nonsonication treatments were established according to growth of S. cerevisiae showed that the model fitted well with Logistic regression in which the strain specific growth rate increased by 60.95% after sonication. GSH production model agreed with Luedeking‐Piret regression in which GSH synthesis parameters of sonication, α and β increased by 1.96% and 19.64% in comparison to the nonsonicated sample. This study clearly demonstrated that ultrasonic stimulation could improve the biosynthesis of GSH during fermentation. Practical Applications: In this study, the GSH was producted by microbial fermentation in in situ 7.5 L ultrasonic fermentation tank. During the fermentation, sonication was applied to increasing yield of GSH. The results show that the study provides a theoretical basis for manufacture GSH combined with sonication industrialization. The fermentation kinetic model was established, which provided experimental basis for continous fermentation. [ABSTRACT FROM AUTHOR]

Adolescent depression shows high clinical heterogeneity. Brain functional networks serve as a powerful tool for investigating neural mechanisms underlying depression profiles. A key challenge is to characterize how variation in brain functional organization links to behavioral features and psychosocial environmental influences. We recruited 80 adolescents with major depressive disorder (MDD) and 42 healthy controls (HCs). First, we estimated the differences in functional connectivity of resting-state networks (RSN) between the two groups. Then, we used sparse canonical correlation analysis to characterize patterns of associations between RSN connectivity and symptoms, cognition, and psychosocial environmental factors in MDD adolescents. Clustering analysis was applied to stratify patients into homogenous subtypes according to these brain-behavior-environment associations. MDD adolescents showed significantly hyperconnectivity between the ventral attention and cingulo-opercular networks compared with HCs. We identified one reliable pattern of covariation between RSN connectivity and clinical/environmental features in MDD adolescents. In this pattern, psychosocial factors, especially the interpersonal and family relationships, were major contributors to variation in connectivity of salience, cingulo-opercular, ventral attention, subcortical and somatosensory-motor networks. Based on this association, we categorized patients into two subgroups which showed different environment and symptoms characteristics, and distinct connectivity alterations. These differences were covered up when the patients were taken as a whole group. This study identified the environmental exposures associated with specific functional networks in MDD youths. Our findings emphasize the importance of the psychosocial context in assessing brain function alterations in adolescent depression and have the potential to promote targeted treatment and precise prevention. • Elucidating associations between psychosocial environment, behaviors, and brain function using multivariate mapping approach. • Interpersonal and family relationship stress contributed most to variation in functional connectivity of adolescent depression. • Based on brain-behavior-environment association, MDD youths were categorized into two subgroups with distinct characteristics. [ABSTRACT FROM AUTHOR]

Tip-jet technology has potential value for application in vertical take-off and landing or short take-off and landing concept aircraft. The main objective of this current work is to investigate the effects of the tip-jet on the performance of a ducted fan in hover. The overall flow field of the ducted fans with tip-jet was simulated by using the shear-stress transport k-omega turbulence model with a refined high-quality structured grid at various rotational speeds. The comparative analysis of the performances of the ducted fans with different tip-jet locations was carried out. The results indicate that the circulation of the blade with tip-jet is affected by the flow blockage, Coanda effect, and edge-shed vortex. These flow features were formed by the tip-jet. The fan's thrust could be augmented when the nozzle was a little farther from the blade trailing edge. However, a higher jet flow utility efficiency could be achieved when the nozzle was close to the blade trailing edge. [ABSTRACT FROM AUTHOR]

Waverider-inlet integration design is an important approach to realize hypersonic flight. The inlet lip is the key factor for internal/external flow field coupling. This paper proposes a novel 3D inverse method of characteristics (MOC) to design the inlet lip with generalized 3D shock. The unit process and marching procedure of the inverse MOC in 2D and 3D focus on obtaining the unique coordinates of the solution points. The accuracy of inverse MOC is verified through its comparison with the analytical solution of a conical flow field. The approach is then applied for a hypersonic bump-inlet integration (The freestream Mach number M ∞ = 6.0), where the inlet lip is inversely generated by a prescribed elliptic-conical shock wave. Inviscid results reveal good performance (The mass capturing ratio φ = 0.813, the Mach number of inlet exit M exit = 3.71, the total pressure recovery coefficient σ = 0.752). The incident shock is well attached on the inlet lip, which is of high φ. Viscous results show relatively low performance (φ = 0.738, M exit = 2.94, σ = 0.471), which indicates that the new method is a promising solution for the hypersonic internal/external coupling flow. Although the viscous effects should be further considered to improve the design, the proposed method can be applied to 3D surface design with generalized shock shapes. • An inverse MOC is developed to design 3D surface with generalized shock shapes. • The method ensures a unique solution and high accuracy for inviscid design. • The inlet mass capturing ratio is 0.813 subjected to Mach 6 non-uniform inflow. • It is a promising solution for the hypersonic internal/external coupling flow. [ABSTRACT FROM AUTHOR]

The fruit preservation industry in developing countries is growing rapidly and presents unique opportunities for promoting environmental sustainability. However, very few life cycle assessment studies have evaluated the environmental performances of current production technologies in developing countries. This study represents the first life cycle assessment to compare two common production lines of the preserved plum industry in Southern China and suggested strategies for improving their environmental performances. The first line, commonly adopted by medium-sized plants, included washing, osmotic treatment, blanching, superheated steam coupled with far-infrared radiation for drying, packaging and wastewater treatment stages. The second line, commonly utilized by small-sized plants, consisted of washing, osmotic treatment, drying by natural ventilation, packaging and wastewater treatment stages. The comparison suggested that the first production line resulted in higher fossil fuel depletion, ozone depletion, human health noncancer, respiratory and ecotoxicity impacts than the second production line. In contrast, the second production line resulted in higher photochemical formation, global warming, acidification, human health cancer and eutrophication impacts. Electricity and wastewater treatment, together, were the dominating contributors to most of the life cycle environmental impact categories. The sensitivity analyses suggested that the life cycle global warming impacts were most sensitive to electricity use, while the wastewater amount ranked as the most influential factor for the life cycle eutrophication impacts. In addition, the scenario analyses indicated that upgrading the activated sludge process to a membrane bioreactor process, for in-plant wastewater treatment, alone would increase life cycle fossil fuel depletion, photochemical formation, acidification and respiratory impacts. However, the combinational adoption of a membrane bioreactor process and electricity derived from wind or lignocellulosic biomass can significantly reduce life cycle environmental impacts of the plum preservation plants. [ABSTRACT FROM AUTHOR]

A method is developed to solve biglobal stability functions in curvilinear systems which avoids reshaping of the airfoil or remapping the disturbance flow fields. As well, the biglobal stability functions for calculation in a curvilinear system are derived. The instability features of the flow over a NACA (National Advisory Committee for Aeronautics) 0025 airfoil at two different angles of attack, corresponding to a flow with a separation bubble and a fully separated flow, are investigated at a chord-based Reynolds number of 100 000. The most unstable mode was found to be related to the wake instability, with a dimensionless frequency close to one. For the flow with a separation bubble, there is an instability plateau in the dimensionless frequency ranging from 2 to 5.5. After the plateau and for an increasing dimensionless frequency, the growth rate of the most unstable mode decreases. For a fully separated flow, the plateau is narrower than that for the flow with a separation bubble. After the plateau, with an increased dimensionless frequency, the growth rate of the most unstable mode decreases and then increases once again. The growth rate of the upstream shear layer instability was found to be larger than that of the downstream shear layer instability. [ABSTRACT FROM AUTHOR]

Dynamic mode decomposition is a useful method for extracting temporal information of coherent structures in unsteady flows. However, this method cannot simultaneously extract temporal and spatial development information, including wave number and spatial growth rate, which is essential in fully developed flows. Thus, using the idea of spatio–temporal dynamic mode decomposition from Le Clainche & Vega, we established an algorithm for spatio–temporal dynamic mode decomposition through element rearrangement, matrix blocking, and re-decomposition techniques, based on the traditional dynamic mode decomposition. This method can calculate the spatio–temporal modes of an unsteady function whose space dimension exceeds two. Each spatio–temporal mode is characterized by temporal growth rate, angular frequency, spatial growth rate, and wave number, thereby expanding the dimension of acquiring information of unsteady flow fields. The feasibility and effectiveness of this method are verified by a function of time and space. The application of spatio–temporal dynamic mode decomposition in a typical unsteady shear layer flow shows that this method can capture the dominant coherent structure in the flow field and accurately acquire its spatio–temporal evolution information. [ABSTRACT FROM AUTHOR]

This work aims to investigate the availability of a tip-jet on a ducted fan under large blade pitch angle and high solidity conditions. The aerodynamic performance and flow field of a ducted fan in hover are numerically investigated over a range of blade pitch angles at three operating speeds. A numerical experiment is conducted using the shear-stress transport k-omega turbulence model with a refined high-quality structured grid. The maximum thrust, peak efficiency, and stall margin of the ducted fan with tip-jet are the main interests of this investigation. Results indicate a 30% increase in the thrust of the fan with tip-jet near stall margin condition. This aerodynamic improvement seems to increase with the blade pitch angle because the separation flow at the front part of the blade becomes uniform and reattaches to the blade surface due to the entrainment effect of the tip-jet. The nozzle with an angle in downwash direction can improve tip-jet efficiency at a large blade pitch angle. The tip-jet is applicable to a fan with a large pitch angle and high solidity. [ABSTRACT FROM AUTHOR]

Highlights • The mini-scale laminar flow which is asynchronous and intermittent is presented for a micro swing engine recuperator. • Axial wall heat conduction has become more significant in this flow type than the steady state. • The temperature fluctuation in solid wall for intermittent pulsed flow will further reduce heat transfer efficiency. • Heat transfer in the flow is dually affected by wall thickness ratio and flow frequency, whose mechanism is proved. Abstract A numerical investigation into conjugate heat transfer for a double-tube heat exchanger in mini-scale was conducted, with an asynchronous intermittent laminar flow imposed at the inlets. As a basic component of the micro recuperator for a micro swing engine, a mini double-tube exchanger under the same flow conditions was chosen as the physical model with consideration of variable fluid properties. Results indicate that, for the asynchronous intermittent pulsed flow, the axial wall heat conduction is much more serious and the periodic fluctuation of the solid wall temperature further worsens the heat transfer efficiency. Two dimensionless numbers R ∗ and C ¯ ∗ are proposed to evaluate the two adverse effects. Then, two key parameters involved in the design of the micro recuperator for the micro swing engine are studied, namely, wall thickness ratio δ / D c and flow frequency. For certain flow frequencies, as the value of δ / D c increases, the axial heat conduction is enhanced while the wall temperature fluctuation is reduced. For a given δ / D c , the flow frequency dually affects the heat exchanger efficiency and the optimum frequency exists. The optimal value increases with the wall thickness ratio. These results lay a good foundation of the micro recuperator design for the micro swing engine. [ABSTRACT FROM AUTHOR]

Abstract An innovative type of pressure distribution for the hypersonic aircraft forebody (bump) is presented, and this design is based on the newly established known as pressure ridge (PR) flow mechanism. Studies on the low-kinetic-energy fluid over the aircraft surface are summarized. Then, the challenges of the inlet–airframe integration at high speeds are discussed. The flow structure around the bump is analyzed in detail to eliminate the side-embedded shock (SES) effect at the inlet entrance. The concept of PR is proposed to improve the overall aerodynamic characteristics of the bump, namely, the boundary layer removal, the reduction of external drag, and the streamline direction at bump end-section. On the basis of the developed inverse method to generate the bump surface by the prescribed pressure distribution, the improved PR-derived bump is designed and numerically compared with the typical pressure-controllable bump (PCB) while the identical leading edge profile is imposed. Results demonstrate that the PR creates outward and inward pressure gradients. The removed amount of boundary layer increases with the increase in outward pressure gradient. Meanwhile, the inward pressure gradient determines the streamline pattern after the bump. The PR-derived bump is 29.2% lower in height than the typical one by using a proper outward pressure gradient. The uniform area of the new bump is 30% wider than that of the typical PCB. The near-wall streamlines of the new bump are adjusted from expanding to the parallel, thereby relieving the side-compression. Changing the location, width, and peak value of the PR can lead to great flexibility in the design and optimization of aircraft forebody subjected to hypersonic flow. [ABSTRACT FROM AUTHOR]

Highlights • Highest yield of yoghurt peptides was obtained in ultrasound-treated fermentation. • An empirical model was established for predicting the yield of yoghurt peptides. • Ultrasound-immediately-activated extracellular enzymes resulted in peptide increase. • Ultrasound-activated enzyme activity disappeared after ultrasound was removed. Abstract Herein the effect of low intensity ultrasound on the fermentation of skim milk medium by Lactobacillus paracasei were investigated to obtain optimum ultrasonic conditions for the highest yield of yoghurt peptides. The results showed that the fermented skim milk medium treated with ultrasound with its seed culture without ultrasonic treatment was an optimum scheme. In this scheme with the ultrasonic conditions of 28 kHz, ultrasonic pulsed model of on-time 100 s and off-time 10 s, 100 W/L for the treatment time of 30 min after the fermentation time of 9 h, the peptide content in the fermented skim milk media increased by 49.5% and the viable cells in the same media increased by 43.5% compared with those in the untreated samples. By response surface methodology (RSM) analysis and its verification experiments, a reasonably accurate empirical model was established for investigating and predicting the relationship between skim milk concentration, ultrasonic treatment time, power and the yield of yoghurt peptides. The former two parameters 12.6% w/v and 35 min were taken in the verification experiments in which the peptide content of the fermented media reached 5.9 mg/mL with an increase by 64.23% and the peptide yield was 14.2%, similar to its theoretical value of 14.6% according to the empirical model. The comparison of extracellular enzyme activities in the fermented skim milk media between with and without ultrasonic treatment under the conditions in the optimum scheme indicated that the mechanism of the ultrasound-activated peptide content increment might be the extracellular enzyme activities immediately activated by the ultrasound, effect of which would disappear in the progress of fermentation after the ultrasound was removed. [ABSTRACT FROM AUTHOR]

Dealing with high transonic airflow at the outlet of a mixed-flow impeller is a challenging issue in research on the design of efficient and compact diffusers. A low aspect ratio and an adverse pressure gradient in the passage of the diffuser can lead to flow separation on the hub side of the bend and the suction side of the aft blade. Tandem blading can be used to attain flow control through an appropriate relative circumferential tandem position (λ). However, a comprehensive understanding of flow in a compact crossover tandem diffuser (CTD) requires further investigation. This study provides a detailed analysis of the mechanism of flow in a compact crossover baseline tandem diffuser (CBTD) as well as the influence of different values of λ on the structure of flow of the CTD. The findings show that the CBTD can suppress secondary flow separation on the hub side of the bend by reasonably distributing the radial load. We also found that a value of λ of 75% can delay the point of separation on the suction side of the aft blade over a wide range of spans, where this inhibits the corner separation vortex and improves the structure of flow and performance of the diffuser. We also preliminarily explore the impacts of excitation of full-span jet intensities with different values of λ on the corner separation vortex on the suction side of the aft blade and offer guidance for the design of a compact and efficient CTD. [ABSTRACT FROM AUTHOR]