A dimensional analysis of supersaturated total dissolved gas dissipation

Elevated levels of total dissolved gas (TDG) may occur downstream of dam discharges, leading to increased incidence of gas bubble disease in fish. Accelerating the dissipation of supersaturated TDG in the downstream river can mitigate this negative problem. However, developing effective mitigation techniques is hampered by limitations in present models of TDG dissipation processes. Furthermore, data useful for modelling the dissipation of supersaturated TDG through the free surface in natural rivers are limited. Past studies indicated that the TDG dissipation process is quantitatively different from the reaeration process, and TDG behavior is quantitatively different from dissolved oxygen. However, a correct parameterization of the TDG dissipation process is still missing. The paper presents a novel dimensional analysis of the dissipation of supersaturated TDG. This approach can provide a relationship between the TDG dissipation coefficient and some classical fluid mechanics index-numbers. This dimensional analysis considers some key parameters for the dissipation process both water and TDG properties as well as flow characteristics, including turbulence. These parameters are water kinematic viscosity, TDG molecular diffusivity and vertical turbulent diffusivity, and channel width. The application of dimensional analysis pointed out that the TDG dissipation coefficient is a function of the Schmidt number, the aspect ratio of the channel, and the shear Reynolds number. The dimensional analysis was then verified using both field data collected in some large natural rivers and reservoirs in Sichuan and experimental data in laboratory flume at State Key Laboratory of Hydraulics and Mountain River Engineering of Sichuan University. The analysis revealed the key role of turbulence in controlling the TDG dissipation while the importance of gas/water characteristics remains still unclear and needs further investigations

Numerical Simulation of Turbulent Flow Past a Cylinder Placed Downstream of a Step

This study investigates the effect on the flow structure in a backward-facing step (BFSF) due to a cylinder placed downstream of the step. Numerical simulations were carried out using OpenFOAM with several turbulence models (standard k-ɛ, RNG k-ɛ, standard k-ω, and SST k-ω). The recirculating flow, the skin friction coefficient (Cf), and the pressure coefficient (Cp) of the bottom wall were comparatively analyzed. The added cylinder modified the structure of flow and increased the skin friction coefficient (Cf) in the recirculation zone. Also, the pressure coefficient of the bottom wall increased immediately downstream of the cylinder and farther downstream of the reattachment point remained stable in the flow recovery process

Influence of a rigid cylinder on flow structure over a backward-facing step

In the present study, laminar and turbulent flow over a backward-facing step (BFSF) where a cylinder was placed immediately downstream of the step was investigated through numerical simulation using OpenFOAM. In laminar flow mean errors between numerical and literature experimental data for velocity profiles and reattachment lengths were lower than 8.1% and 18%, respectively. The cylinder significantly modified the structure of recirculating flow over the BFSF. In addition, the cylinder increased the skewness of the velocity profiles, and the location of the maximum velocity shifted towards the upper wall. In turbulent flow, the results from several RANS models (standard k-ɛ, RNG k-ɛ, standard k-ω, SST k-ω, and RSM (SSG)) were compared with literature experimental data. The average error in predicting reattachment length and velocity profiles ranged from 2.2% to 28.5% and from 7.8% to 14.5%, respectively. The most accurate model in predicting reattachment length and velocity profiles was the standard k-ɛ and SST k-ω models respectively. The cylinder modified flow structure and the distribution of turbulent kinetic energy, whose largest value was found downstream of a cylinder in the separated shear laye

Randomness representation of turbulence in canopy flows using Kolmogorov complexity measures

Turbulence is often expressed in terms of either irregular or random fluid flows, without quantification. In this paper, a methodology to evaluate the randomness of the turbulence using measures based on the Kolmogorov complexity (KC) is proposed. This methodology is applied to experimental data from a turbulent flow developing in a laboratory channel with canopy of three different densities. The methodology is even compared with the traditional approach based on classical turbulence statistics

Turbulent flow structures and scour hole characteristics around circular bridge piers over non-uniform sand bed channels with downward seepage

Bridges play an important role in the transportation of goods and people across rivers. In civil engineering, one of the most important issues is to protect bridge piers from collapse. In fact, their foundation may be threatened by localized scour, as a result of the flow constriction of the cross-sectional area, and the subsequent increase of the flow velocity [1]. Thus, in order to ensure the protection of such structures, it is of a high priority to predict the flow field and sediment transport around the bridge piers. Many researchers have studied the vortice systems around piers, stating that they primarily aect the local scour [2–6]. Melville and Coleman [5] stated that the flow field around a bridge pier is characterized by down-flow, surface roller, and wake vortices, such as the horseshoe vortex, at the base of the pier, and wake vortices behind the pier. According to Melville [2] and Chiew [4], a horseshoe vortex increases the flow velocity near the bed, and the wake vortex carries the eroded bed material downstream. However, the eect of the pier on flow separation, and the consequent sediment transport, depends on turbulence. Some studies have investigated the stochastics nature of turbulent flow around a pier [2,7–11], but there still remains a lack information concerning the trend of higher order moments for the fluctuating velocities

Plant miRNA Cross-Kingdom Transfer Targeting Parasitic and Mutualistic Organisms as a Tool to Advance Modern Agriculture

MicroRNAs (miRNAs), defined as small non-coding RNA molecules, are fine regulators of gene expression. In plants, miRNAs are well-known for regulating processes spanning from cell development to biotic and abiotic stress responses. Recently, miRNAs have been investigated for their potential transfer to distantly related organisms where they may exert regulatory functions in a cross-kingdom fashion. Cross-kingdom miRNA transfer has been observed in host-pathogen relations as well as symbiotic or mutualistic relations. All these can have important implications as plant miRNAs can be exploited to inhibit pathogen development or aid mutualistic relations. Similarly, miRNAs from eukaryotic organisms can be transferred to plants, thus suppressing host immunity. This two-way lane could have a significant impact on understanding inter-species relations and, more importantly, could leverage miRNA-based technologies for agricultural practices. Additionally, artificial miRNAs (amiRNAs) produced by engineered plants can be transferred to plant-feeding organisms in order to specifically regulate their crosskingdom target genes. This minireview provides a brief overview of cross-kingdom plant miRNA transfer, focusing on parasitic and mutualistic relations that can have an impact on agricultural practices and discusses some opportunities related to miRNAbased technologies. Although promising, miRNA cross-kingdom transfer remains a debated argument. Several mechanistic aspects, such as the availability, transfer, and uptake of miRNAs, as well as their potential to alter gene expression in a cross-kingdom manner, remain to be addressed

Anisotropy in the Turbulent Flow through Random and Emergent Rigid Vegetation on Rough Beds

In this study, we explore for the first time the turbulence anisotropy of flows through random and emergent rigid vegetation on rough beds, using the anisotropy invariant maps (AIMs). We present the results of an experimental campaign, based on Acoustic Doppler Velocimeter (ADV) measures, varying the bed sediment size (coarse sand, fine gravel, and coarse gravel), under the same hydraulic conditions. The evolution of the stress ellipsoid formed by the Reynolds stresses is discussed, together with the analysis of the anisotropic invariant function. We demonstrate that vegetation distribution is of paramount importance in the turbulence anisotropy evolution along the water depth. While in the case of a regular pattern the bed roughness is the key parameter in determining the shape of the stress ellipsoid in the near-bed region, in a random vegetation distribution this assumption is no longer valid. However, by increasing the bed roughness in such kind of arrangement, its effect on the turbulence anisotropy are visible in specific areas around the vegetation stem. This is confirmed by the analysis of the anisotropic invariant function calculated for different sections close to the stem itself

Quinic acids from Aster caucasicus and from transgenic callus expressing a beta-amyrin synthase.

Several different classes of secondary metabolites, including flavonoids, triterpenoid saponins and quinic acid derivatives, are found in Aster spp. (Fam. Asteraceae). Several Aster compounds revealed biological as well as pharmacological activities. In this work, a phytochemical investigation of A. caucasicus evidenced the presence of quinic acid derivatives, as well as the absence of triterpene saponins. To combine in one species the production of different phytochemicals, including triterpenes, an Agrobacterium-mediated transformation of A. caucasicus was set up to introduce A. sedifolius β-amyrin synthase (AsOXA1)-encoding gene under the control of the constitutive promoter CaMV35S. The quali-quantitative analysis of transgenic calli with ectopic expression of AsOXA1 showed, in one sample, a negligible amount of triterpene saponins combined with higher amount of quinic acid derivatives as compared with the wild type callus

Association between Sarcopenia and Reduced Bone Mass: Is Osteosarcopenic Obesity a New Phenotype to Consider in Weight Management Settings?

Sarcopenic obesity (SO) is a frequent phenotype in people with obesity; however, it is unclear whether this links with an impaired bone status. In this study, we aimed to investigate the association between SO and low bone mass, and to assess the prevalence of a new entity that combines excessive fat deposition, reduced muscle mass and strength, and low bone mass defined as osteosarcopenic obesity (OSO). Body composition was completed by a DXA scan in 2604 participants with obesity that were categorized as with or without SO, and with low or normal bone mineral content (BMC). Participants with both SO and low BMC were defined as OSO. Among the entire sample, 901 (34.6%) participants met the criteria for SO. This group showed a reduced mean BMC (2.56 ± 0.46 vs. 2.85 ± 0.57, p < 0.01) and displayed a higher prevalence of individuals with low BMC with respect to those without SO (47.3% vs. 25.9%, p < 0.01). Logistic regression analysis showed that the presence of SO increases the odds of having low BMC by 92% [OR = 1.92; 95% CI: (1.60–2.31), p < 0.05] after adjusting for age, body weight, and body fat percentage. Finally, 426 (16.4%) out of the total sample were affected by OSO. Our findings revealed a strong association between SO and reduced bone mass in adults with obesity, and this introduces a new phenotype that combines body fat, muscle, and bone (i.e., OSO) and appears to affect 16% of this population

Group therapy with peer support provider participation in an acute psychiatric ward: 1-year analysis

Background: Group psychotherapy improves therapeutic process, fosters identification with others, and increases illness awareness; (2) Methods: In 40 weekly group sessions held in an acute psychiatric ward during one year, we retrospectively evaluated the inpatients’ participation and the demographic and clinical variables of the individuals hospitalized in the ward, the group type according to Bion’s assumptions, the main narrative themes expressed, and the mentalization processes by using the Mentalization-Based Therapy-Group Adherence and Quality Scale (MBT-GAQS); (3) Results: The “working” group was the prevailing one, and the most represented narrative theme was “treatment programs”; statistically significant correlations were found between the group types according to Bion’s assumptions and the main narrative themes (Fisher’s exact, p = 0.007); at our multivariate linear regression, the MBT-G-AQS overall occurrence score (dependent variable) was positively correlated with the number of group participants (coef. = 14.87; p = 0.011) and negatively with the number of participants speaking in groups (coef. = −16.87, p = 0.025); (4) Conclusion: our study suggests that the group shows consistent defense mechanisms, relationships, mentalization, and narrative themes, which can also maintain a therapeutic function in an acute ward