Annelids shed light on the evolution of spiralian development

Spiralian development is characterized by stereotypic cell geometry and spindle orientation in early cleavage stage embryos, as well as conservation of ultimate fates of descendent clones. Diverse taxa such as molluscs, annelids, flatworms, and nemerteans exhibit spiralian development, but it is a mystery how such a conserved developmental program gives rise to such diverse body plans. This review highlights examples of variation during early development among spiralians, emphasizing recent experimental studies in the annelid Capitella teleta Blake, Grassle and Eckelbarger, 2009. Intracellular fate mapping studies in C. teleta reveal that many of its cells’ fates are shared among spiralians, but it also has a novel origin for trunk mesoderm (3c and 3d micromeres). Studies have identified an inductive signal in spiralians that has “organizing activity” and that influences cell fates in the surrounding embryo. Capitella teleta also has an organizing activity; however, surprisingly, it is localized to a different cell, it signals at a different developmental stage, and likely utilizes a distinct molecular signaling pathway compared with that in molluscs. A model is presented to provide a mechanistic explanation of evolutionary changes in the cellular identity of the organizer. Detailed experimental investigations in spiralian embryos demonstrate variation in developmental features that may influence the evolution of novel forms.

Download Full-text

New Tricks for an Old (Hedge)Hog: Sonic Hedgehog Regulation of Astrocyte Function

Cells ◽

10.3390/cells10061353 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1353

Author(s):

A. Denise R. Garcia

Keyword(s):

Signaling Pathway ◽

Sonic Hedgehog ◽

Synapse Formation ◽

Inflammatory Responses ◽

Molecular Signaling ◽

Synaptic Organization ◽

Shh Signaling ◽

Broad Array ◽

And Function ◽

Molecular Signaling Pathway

The Sonic hedgehog (Shh) molecular signaling pathway is well established as a key regulator of neurodevelopment. It regulates diverse cellular behaviors, and its functions vary with respect to cell type, region, and developmental stage, reflecting the incredible pleiotropy of this molecular signaling pathway. Although it is best understood for its roles in development, Shh signaling persists into adulthood and is emerging as an important regulator of astrocyte function. Astrocytes play central roles in a broad array of nervous system functions, including synapse formation and function as well as coordination and orchestration of CNS inflammatory responses in pathological states. Neurons are the source of Shh in the adult, suggesting that Shh signaling mediates neuron–astrocyte communication, a novel role for this multifaceted pathway. Multiple roles for Shh signaling in astrocytes are increasingly being identified, including regulation of astrocyte identity, modulation of synaptic organization, and limitation of inflammation. This review discusses these novel roles for Shh signaling in regulating diverse astrocyte functions in the healthy brain and in pathology.

Download Full-text

Experimental Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

Mine Water and the Environment ◽

10.1007/s10230-021-00807-w ◽

2021 ◽

Author(s):

Parviz Enany ◽

Oleksandr Shevchenko ◽

Carsten Drebenstedt

Keyword(s):

Water Flow ◽

High Efficiency ◽

Experimental Studies ◽

Theoretical Models ◽

Injection System ◽

Experimental Investigations ◽

Flow Mode ◽

New Device ◽

Riser Pipe ◽

Airlift Pump

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

Download Full-text

ДОСЛІДЖЕННЯ ГІГІЄНІЧНИХ ВЛАСТИВОСТЕЙ МАТЕРІАЛІВ НАТІЛЬНОЇ ЛІКАРНЯНОЇ БІЛИЗНИ

Bulletin of the Kyiv National University of Technologies and Design Technical Science Series ◽

10.30857/1813-6796.2019.6.4 ◽

2020 ◽

Vol 140 (6) ◽

pp. 38-47

Author(s):

І. О. Іванов ◽

Н. П. Супрун ◽

Ю. О. Ващенко

Keyword(s):

Comparative Analysis ◽

Materials Science ◽

Experimental Studies ◽

Operating Conditions ◽

Raw Material ◽

Experimental Investigations ◽

Textile Materials ◽

Composition And Structure ◽

Innovative Materials ◽

Basic Functions

Investigation of the influence of the peculiarities of raw material composition and structure of traditional and innovative linen textile materials on their hygienic properties. Theoretical and experimental investigations are based on the main positions of textile materials science. In experimental studies, modern standardized methods for determining the hygienic properties of textile materials were used, as well as techniques specially developed taking into account the peculiarities of the operating conditions of underwear. The peculiarities of the operating conditions and the basic functions of hospital underwear were determined. The comparative analysis of hygienic properties of traditional and modern fabrics for underwear was carried out. Using the standardized and the developed methods, adapted to the peculiarities of the conditions of use of the products, the indicators characterizing the processes of water absorption of the materials were experimentally determined. On the basis of the obtained values of quality indicators, a comprehensive assessment of the ability of materials to transfer moisture and air, with the calculation of the arithmetic complex quality index was done. This allowed to determine the material that is optimal in properties, which provides thermophysiological comfort when operating hospital underwear. Using the developed methods, which take into account the specifics of the operating conditions, a comparative analysis of the hygienic properties of traditional and innovative materials for underwear was carried out. A new range of textile materials for underwear has been proposed, taking into account the peculiarities of the operational situation of consumption.

Download Full-text

Design and Experimental Investigations on NOx Emission Control Using FOCDM (Fractional-Order-Based Coefficient Diagram Method)-PIλDµ Controller

Journal Européen des Systèmes Automatisés ◽

10.18280/jesa.530512 ◽

2020 ◽

Vol 53 (5) ◽

pp. 695-703

Author(s):

Maheswari Chennippan ◽

Priyanka E. Bhaskaran ◽

Thangavel Subramaniam ◽

Balasubramaniam Meenakshipriya ◽

Kasilingam Krishnamurthy ◽

...

Keyword(s):

Fractional Order ◽

Packed Column ◽

Experimental Studies ◽

Pso Algorithm ◽

Experimental Investigations ◽

Nox Removal ◽

Diagram Method ◽

Coefficient Diagram Method ◽

Fractional Order Controller ◽

G Ratio

This paper aims to explore experimental studies on the NOx removal process by using pilot plant packed column experimental hardware. Physical modeling based on chemical absorption equations is used to estimate the diameter concerning the height and L/G ratio. Hydrogen peroxide is used as the additive for achieving high NOx removal efficiency. The absorbent entering into the packed column has been controlled by varying its flow rate through the fractional order controller. The FOCDM-PIλDµ controller tuning parameters such as KP, τI, τD are determined using CDM (Coefficient Diagram Method) PID control strategy and the additional parameters of FOCDM-PIλDµ controller such as λ and µ are determined based on the PSO algorithm. The comparative analysis is performed with classical controllers like ZN-PID along with the CDM-PID controllers.

Download Full-text

Experimental studies and numerical modelling of heat and mass transfer process in shell-and-tube heat exchangers with compact arrangements of tube bundles

MATEC Web of Conferences ◽

10.1051/matecconf/201824002006 ◽

2018 ◽

Vol 240 ◽

pp. 02006 ◽

Cited By ~ 2

Author(s):

Valery Gorobets ◽

Yurii Bohdan ◽

Viktor Trokhaniak ◽

Ievgen Antypov

Keyword(s):

Mass Transfer ◽

Numerical Modelling ◽

Heat And Mass Transfer ◽

Heat Exchangers ◽

Experimental Studies ◽

Mass Transfer Process ◽

Experimental Investigations ◽

Transfer Processes ◽

Tube Bundles ◽

Shell And Tube

Shall-and-tube heat exchangers based on the bundles with in-line or staggered arrangements have been widely used in industry and power engineering. A large number of theoretical and experimental works are devoted to study of hydrodynamic and heat transfer processes in such bundles. In that, works the basic studies of heat and mass transfer for these bundles are found. However, heat exchangers of this type can have big dimensions and mass. One of the ways to improve the weight and dimensions of the shell-and-tube heat exchangers is to use compact arrangement of tube bundles. A new design of heat exchanger is proposed, in which there are no gaps between adjacent tubes that touch each other. Different geometry of these tube bundles with displacement of adjacent tubes in the direction of transverse to the flow is considered. Numerical modelling and experimental investigations of hydrodynamic, heat and mass transfer processes in such tube bundles has been carried out. The distribution of velocities, temperatures, and pressure in inter-tube channels have been obtained.

Download Full-text

A new class of nonreciprocal spin waves on the edges of 2D antiferromagnetic honeycomb nanoribbons

Scientific Reports ◽

10.1038/s41598-019-51646-3 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

D. Ghader ◽

A. Khater

Keyword(s):

Spin Waves ◽

Experimental Studies ◽

Classical Field Theory ◽

Experimental Investigations ◽

Theory Approach ◽

Magnetic Excitations ◽

Spintronic Devices ◽

New Class ◽

Potential Applications ◽

Edge Spin

Abstract Antiferromagnetic two-dimensional (2D) materials are currently under intensive theoretical and experimental investigations in view of their potential applications in antiferromagnet-based magnonic and spintronic devices. Recent experimental studies revealed the importance of magnetic anisotropy and of Dzyaloshinskii-Moriya interactions (DMI) on the ordered ground state and the magnetic excitations in these materials. In this work we present a robust classical field theory approach to study the effects of anisotropy and the DMI on the edge and bulk spin waves in 2D antiferromagnetic nanoribbons. We predict the existence of a new class of nonreciprocal edge spin waves, characterized by opposite polarizations in counter-propagation. These novel edge spin waves are induced by the DMI and are fundamentally different from conventional nonreciprocal spin waves for which the polarization is independent of the propagation direction. We further analyze the effects of the edge structures on the magnetic excitations for these systems. In particular, we show that anisotropic bearded edge nanoribbons act as topologically trivial magnetic insulators with potentially interesting applications in magnonics. Our results constitute an important finding for current efforts seeking to establish unconventional magnonic devices utilizing spin wave polarization.

Download Full-text

Effect of a Strawberry and Spinach Dietary Supplement on Spatial Learning in Early and Late Middle-Aged Female Rats

Antioxidants ◽

10.3390/antiox8010001 ◽

2018 ◽

Vol 8 (1) ◽

pp. 1

Author(s):

Paula Millin ◽

Gina Rickert

Keyword(s):

Dietary Supplement ◽

Middle Age ◽

Experimental Studies ◽

Female Rats ◽

Superior Performance ◽

Experimental Investigations ◽

Standard Diet ◽

Middle Aged ◽

Freeze Dried ◽

Antioxidant Diet

The present experiment sought to determine the effect of an eight-week, high antioxidant, whole-foods dietary supplement on Morris Water Maze performance in early and late middle-aged female rats. To improve ecological validity over past experimental studies, rats in the current study received antioxidants by consuming freeze-dried organic strawberries and spinach rather than by being given food extracts or antioxidant injections. Latency and path length measures both indicated that late middle-aged rats fed the high antioxidant diet performed on a par with the younger animals earlier in training than their standard diet counterparts (p < 0.05). Superior performance was not due to improved fitness in the antioxidant-supplemented rats. Thus, our model showed that a high antioxidant diet of relatively short duration mitigated the mild cognitive decline that was seen in control animals during the developmental period of late middle-age. The current results offer support for the promising role of dietary antioxidants in maintaining cognitive health in normal aging and extend past findings to females, who have been relatively neglected in experimental investigations. Moreover, the current model suggests that the period of transition from early to late middle age is a promising target for dietary intervention in healthy adults.

Download Full-text

Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4041495 ◽

2018 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Harald H. W. Funke ◽

Nils Beckmann ◽

Jan Keinz ◽

Sylvester Abanteriba

Keyword(s):

Gas Turbine ◽

Combustion Process ◽

Experimental Studies ◽

Research Process ◽

Operating Conditions ◽

Experimental Investigations ◽

Dual Fuel ◽

Pure Hydrogen ◽

Ongoing Research ◽

Industrial Gas Turbine

Abstract The dry-low-NOx (DLN) micromix combustion technology has been developed originally as a low emission alternative for industrial gas turbine combustors fueled with hydrogen. Currently, the ongoing research process targets flexible fuel operation with hydrogen and syngas fuel. The nonpremixed combustion process features jet-in-crossflow-mixing of fuel and oxidizer and combustion through multiple miniaturized flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. The paper presents the results of a numerical and experimental combustor test campaign. It is conducted as part of an integration study for a dual-fuel (H2 and H2/CO 90/10 vol %) micromix (MMX) combustion chamber prototype for application under full scale, pressurized gas turbine conditions in the auxiliary power unit Honeywell Garrett GTCP 36-300. In the presented experimental studies, the integration-optimized dual-fuel MMX combustor geometry is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen and syngas fuel. The experimental investigations are supported by numerical combustion and flow simulations. For validation, the results of experimental exhaust gas analyses are applied. Despite the significantly differing fuel characteristics between pure hydrogen and hydrogen-rich syngas, the evaluated dual-fuel MMX prototype shows a significant low NOx performance and high combustion efficiency. The combustor features an increased energy density that benefits manufacturing complexity and costs.

Download Full-text

Thermal-Hydraulic Studies on the Shell-and-Tube Heat Exchanger with Minijets

Energies ◽

10.3390/en12173276 ◽

2019 ◽

Vol 12 (17) ◽

pp. 3276 ◽

Cited By ~ 4

Author(s):

Jan Wajs ◽

Michał Bajor ◽

Dariusz Mikielewicz

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Waste Heat ◽

Experimental Studies ◽

Convection Heat Transfer ◽

Test Facility ◽

Experimental Investigations ◽

Transfer Coefficients ◽

Tube Heat Exchanger ◽

Shell And Tube

In this paper a patented design of a heat exchanger with minijets, with a cylindrical construction is presented. It is followed by the results of its systematic experimental investigations in the single-phase convection heat transfer mode. Based on these results, validation of selected correlations (coming from the literature) describing the Nusselt number was carried out. An assessment of the heat exchange intensification level in the described heat exchanger was done through the comparison with a shell-and-tube exchanger of a classical design. The thermal-hydraulic characteristics of both units were the subjects of comparison. They were constructed for the identical thermal conditions, i.e., volumetric flow rates of the working media and the media temperatures at the inlets to the heat exchanger. The experimental studies of both heat exchangers were conducted on the same test facility. An increase in the heat transfer coefficients values for the minijets heat exchanger was observed in comparison with the reference one, whereas the generated minijets caused greater hydraulic resistance. Experimentally confirmed intensification of heat transfer on the air side, makes the proposed minijets heat exchanger application more attractive, for the waste heat utilization systems from gas sources.

Download Full-text

Numerical and Experimental Studies of Labyrinth Seal Aeroelastic Instability

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4044353 ◽

2019 ◽

Vol 141 (11) ◽

Author(s):

Toshimasa Miura ◽

Naoto Sakai

Keyword(s):

Experimental Studies ◽

Labyrinth Seal ◽

Experimental Investigations ◽

Test Cases ◽

Flutter Suppression ◽

Aeroelastic Instability ◽

Suppression Method ◽

Low Stiffness ◽

Aero Engines ◽

Good Agreement

Abstract A labyrinth seal is commonly used to decrease the flow leakage loss between rotating and static components in aero engines. It is susceptible to aeroelastic instability because of its low stiffness. The aim of this study was to establish methods to predict and suppress it effectively. To achieve this, both numerical and experimental investigations are conducted using ansyscfx and ansys mechanical. These solvers are coupled to simulate the flutter precisely. Also, to assess the accuracy of the simulation qualitatively and quantitatively, a test rig is built. In the first part of this study, the accuracy of the numerical method is confirmed for several test cases with different seal clearance variations. Flutter inception is evaluated in detail for various pressure ratios and rotation speeds. The numerical results show good agreement with the experimental results. It is also confirmed that the aeroelastic instability is very sensitive to the seal clearance variations. These results show the same tendency as those in previous works. In the second part of this study, this paper tries to develop a flutter suppression method with higher leakage performance. This is achieved by changing the seal geometry. To detect the important geometric parameters, the contribution of each geometric component to aeroelastic instability is carefully analyzed. On the basis of this, the seal geometry is modified and its performance is evaluated. The optimized labyrinth seal shows good performance in terms of flow leakage and aeroelastic stability. Through this study, a new flutter suppression method is established.

Download Full-text