The role of turbulent coherent structures on microalgal mixing for nutrient removal in jet and paddlewheel raceway ponds

Outdoor studies were conducted on microalgae cultures in two raceway ponds (kept in constant motion with either jet or paddlewheel) with a flatbed to treat anaerobic digestion piggery effluent and to observe the characteristics of turbulence on microalgal mixing and growth. Acoustic Doppler Velocimeters (ADV) were deployed to record the instantaneous velocity components and acoustic backscatter as a substitution of microalgae concentration. The present research on microalgal mixing considers the effect of event-based turbulent features such as the widely known ‘turbulent bursting’ phenomenon. This is an important aspect, as turbulent coherent structures can result in microalgal mixing, which can lead to significant changes in microalgal growth. The experimental results presented in this paper of two contrasting environments of jet- and paddlewheel-driven ponds suggested that: (1) turbulent bursting events significantly contributed to microalgal mixing when paddlewheels and jets were used; (2) among four type of turbulent bursting events, ejections and sweeps contributed more to the total microalgal mixing; and, (3) a correlation was revealed using wavelet transform between the momentum and microalgal mixing flux when either jet or paddlewheel were used. Such similarities in jet and paddlewheel raceway ponds highlight the need to introduce turbulent coherent structures as an essential parameter for microalgal mixing studies

Role of histaminegic and calcium channels in the inhibitory effects of hydroalcoholic extract of matricaria recutita L. on isolated rabbit jejunum

Introduction: Considering the long traditional history of anti-inflammatory and anti-spasmodic effects of Matricria spices on the gastrointestinal system, the present study aimed to investigate the role of calcium channels and Histamine receptors in the inhibitory effects of hydroalcoholic dry extract of German chamomile (Matricaria recutita L.) on the isolated rabbit jejunum. Methods: All experiments were done on the isolated jejunum of New Zealand rabbits (1.8-2.5 kg). Dry extract of aerial parts of M. recutita was obtained by the maceration technique. The study was performed on two groups (n=6 in each group). In the first group, the effects of cumulative concentrations of M. recutita (3×10-3-1×10-2 mg/ml) on normal and K+-induced contractions (50 mM) of isolated jejunum were studied. In the second group, the inhibitory role of M. recutita (3 – 13×10-3 mg/ml) was evaluated in the presence and absence of histamine and cetrizine. In the presence and absence of 10 μM certizine, a histamine H1-antagonist, a concentration-dependent inhibitory effect of M. recutita extract in the range of 3-13×10-3 mg/ml was recorded the rabbit jejunum. Results: Results showed that EC50 of M. recutita in the absence and presence of K+ was 6.3×10-3 and 6.5×10- 3mg/ml, respectively. IC50 values for two concentrations of M. recutita (8×10-3 , 1×10-2 ) to abrogated contractive phase of Histamine was 9.55 × 10-6 and 1.57 × 10-6 μM. Cetrizine (10 μM) abolished inhibitory effects of M. recutita (IC50=3.6×10-3), (p< 0.001). Conclusion: Dry extract of matricaria recutita had inhibitory effects on the contractions of isolated rabbit jejunum. Calcium channels and histamine were involved in these antispasmodic effects

Protective role of cyclosporine on the model simulated the rotational nodal arrhythmia (AVNRT) by using extracellular field potential recordings of isolated atrioventricular-node of rabbit

Introduction: Recent studies have shown acute cardioprotective effects of cyclosporine. The aim of the present study was to determine the protective role of cyclosporine on the model simulated the rotational nodal arrhythmia (AVNRT) by using extracellular field potential recordings of isolated atrioventricular-node (AV-node) of rabbit. Methods: This study was performed on isolated double-perfused AV-node of male New Zealand rabbits (1.5-2.5 kg) in one group (n=7). Basic and rate-dependent stimulation protocols (recovery, facilitation, fatigue) and arrhythmia threshold (index of refractoriness) and % Gap incidence were measured for assessment of electrophysiological properties of the AV- node. All stimulation protocols were repeated in control step and in the presence of various cumulative concentrations of cyclosporine (0.5 - 10 μm). Results: Cyclosporine prolonged the effective refractory period from 114.3±7.9 to 142±7.3 msec at the concentration of 10 μm. It also prolonged the functional refractory period from 162±3.3 to 178.6±5 msec and increased the time of Wenckebach at the concentrations of 5 - 10 μM. Various concentrations of cyclosporine increased fatigue and reached a significant level at 10 μm. Gap incidence was 82%, 16.6% and 20% in the control and treatments with 0.5 and 10 μm of cyclosporine, respectively. Conclusion: Block of MPTP by cyclosporine caused inhibition of basic and rate-dependent properties of atrioventricular node. Cyclosporine, by raising the threshold of arrhythmia, could be possibly considered as an anti- AVNRT drug

Role of nitric oxide on the electrophysiological properties of isolated rabbit atrioventricular node by extracellular field potential during atrial fibrillation

Introduction: The aim of the present study was to determine direct effects of NO modulation on protective electrophysiological properties of atrioventricular node (AV node) in the experimental model of AF in rabbit. Methods: Isolated perfused rabbit AV nodal preparations were used in two groups. In the first group (N=7), LNAME (50μM) was applied. In the second group (N=12), different concentrations of L - argenine (250 μM - 5000 μM) were added to the solution. Programmed stimulation protocols were used to quantify AV nodal conduction time, refractoriness and zone of concealment. AF protocol was executed by software with coupling intervals (ranging from 75–125 msec). Results: L-NAME had depressive effects on basic AV nodal properties. L-Arginine (250μM) had direct inhibitory effects on nodal conduction time, Wenckebach and refractoriness. Significant increases in the number of concealed beats were induced by L-Arginine (500 μM). Number of concealed beats were increased from 700.7±33.7 to 763±21 msec (P<0.05). Trend of zone of concealment prolongation in a frequency-dependent model was abrogated by Larginine (250, 5000 μM). Conclusion: NO at low concentration (in the presence of L-NAME) had facilitatory role on AV nodal properties, but at high concentration (in the presence of L-arginine) enhanced protective role of AV node during AF. Biphasic modulatory role of NO may affect protective behavior of AV node during AF. © 2011, Iranian Society of Physiology and Pharmacology. All rights reserved

Marine health of the Arabian Gulf: Drivers of pollution and assessment approaches focusing on desalination activities

The Arabian Gulf is one of the most adversely affected marine environments worldwide, which results from combined pollution drivers including climate change, oil and gas activities, and coastal anthropogenic disturbances. Desalination activities are one of the major marine pollution drivers regionally and internationally. Arabian Gulf countries represent a hotspot of desalination activities as they are responsible for nearly 50% of the global desalination capacity. Building desalination plants, up-taking seawater, and discharging untreated brine back into the sea adversely affects the biodiversity of the marine ecosystems. The present review attempted to reveal the potential negative effects of desalination plants on the Gulf's marine environments. We emphasised different conventional and innovative assessment tools used to assess the health of marine environments and evaluate the damage exerted by desalination activity in the Gulf. Finally, we suggested effective management approaches to tackle the issue including the significance of national regulations and regional cooperation

Dynamic age-related changes of extracellular field potential of isolated AV-node of rabbit

Introduction: Developmental changes in atrioventricular nodal conduction time and refractoriness have been shown in several studies. Prevalence of atrioventricular nodal reentrant tachycardia (AVNRT) is clearly age-dependent. The purpose of this study was to determine developmental changes of basic and frequency-dependent electrophysiological properties of the atrioventricular node (AV-node) in neonatal and adult rabbits. Methods: In this study, the effects of increasing age on the basic and rate-dependent properties of isolated perfused AV-node were analyzed in neonatal (2-week-old) and adult (12-week-old) New Zealand rabbits. Specific stimulation protocols of recovery, facilitation and fatigue were separately applied in each group (n=7). Unipolar extracellular field potential was recorded by a silver electrode (100 μM). Results: The results showed that the basic nodal properties (ERP, FRP, WBCL and AHmax) were significantly shorter in neonates compared to the adult group. The magnitude of fatigue was also decreased in the neonatal group compared to control (18.9 ±3.3 vs. 11.1 ± 1.2 msec). Time constant of recovery of the adult group was significantly higher than the neonatal group (P<0.05). Conclusion: The results of this study showed that nodal basic and frequency-dependent properties are age-related and different developmental changes of slow and fast pathways are responsible for this behavior and may reveal the grater susceptibility of AVNRT in young adults compared to infants

Effect of shunted piezoelectric control for tuning piezoelectric power harvesting system responses – Analytical techniques

This paper presents new analytical modelling of shunt circuit control responses for tuning electromechanical piezoelectric vibration power harvesting structures with proof mass offset. For this combination, the dynamic closed-form boundary value equations reduced from strong form variational principles were developed using the extended Hamiltonian principle to formulate the new coupled orthonormalised electromechanical power harvesting equations showing combinations of the mechanical system (dynamical behaviour of piezoelectric structure), electromechanical system (electrical piezoelectric response) and electrical system (tuning and harvesting circuits). The reduced equations can be further formulated to give the complete forms of new electromechanical multi-mode FRFs and time waveform of the standard AC-DC circuit interface. The proposed technique can demonstrate self-adaptive harvesting response capabilities for tuning the frequency band and the power amplitude of the harvesting devices. The self-adaptive tuning strategies are demonstrated by modelling the shunt circuit behaviour of the piezoelectric control layer in order to optimise the harvesting piezoelectric layer during operation under input base excitation. In such situations, with proper tuning parameters the system performance can be substantially improved. Moreover, the validation of the closed-form technique is also provided by developing the Ritz method-based weak form analytical approach giving similar results. Finally, the parametric analytical studies have been explored to identify direct and relevant contributions for vibration power harvesting behaviours

Aquaponics: alternative types and approaches

Whilst aquaponics may be considered in the mid-stage of development, there are a number of allied, novel methods of food production that are aligning alongside aquaponics and also which can be merged with aquaponics to deliver food efficiently and productively. These technologies include algaeponics, aeroponics, aeroaquaponics, maraponics, haloponics, biofloc technology and vertical aquaponics. Although some of these systems have undergone many years of trials and research, in most cases, much more scientific research is required to understand intrinsic processes within the systems, efficiency, design aspects, etc., apart from the capacity, capabilities and benefits of conjoining these systems with aquaponics

Dynamically dual vibration absorbers: a bond graph approach to vibration control

This paper investigates the use of an actuator and sensor pair coupled via a control system to damp out oscillations in resonant mechanical systems. Specifically the designs emulate passive control strategies, resulting in controller dynamics that resemble a physical system. Here, the use of the novel dynamically dual approach is proposed to design the vibration absorbers to be implemented as the controller dynamics; this gives rise to the dynamically dual vibration absorber (DDVA). It is shown that the method is a natural generalisation of the classical single-degree of freedom mass–spring–damper vibration absorber and also of the popular acceleration feedback controller. This generalisation is applicable to the vibration control of arbitrarily complex resonant dynamical systems. It is further shown that the DDVA approach is analogous to the hybrid numerical-experimental testing technique known as substructuring. This analogy enables methods and results, such as robustness to sensor/actuator dynamics, to be applied to dynamically dual vibration absorbers. Illustrative experiments using both a hinged rigid beam and a flexible cantilever beam are presented

Conditionally reprogrammed primary airway epithelial cells maintain morphology, lineage and disease specific functional characteristics

© 2017 The Author(s). Current limitations to primary cell expansion led us to test whether airway epithelial cells derived from healthy children and those with asthma and cystic fibrosis (CF), co-cultured with an irradiated fibroblast feeder cell in F-medium containing 10 µM ROCK inhibitor could maintain their lineage during expansion and whether this is influenced by underlying disease status. Here, we show that conditionally reprogrammed airway epithelial cells (CRAECs) can be established from both healthy and diseased phenotypes. CRAECs can be expanded, cryopreserved and maintain phenotypes over at least 5 passages. Population doublings of CRAEC cultures were significantly greater than standard cultures, but maintained their lineage characteristics. CRAECs from all phenotypes were also capable of fully differentiating at air-liquid interface (ALI) and maintained disease specific characteristics including; defective CFTR channel function cultures and the inability to repair wounds. Our findings indicate that CRAECs derived from children maintain lineage, phenotypic and importantly disease-specific functional characteristics over a specified passage range