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•Response Surface Method (RSM) is used for optimizing the wavy-wall profile.•Natural convection heat transfer of nanofluids in a wavy absorber collector is studied.•Finite element ...method (FEM) has been employed to solve the governing equations.•Effect of different boundary conditions on Nusselt number is investigated.
In this paper, the best wavy profile for the bottom plate of a wavy nanofluid-based direct absorber solar collector (WDASC) is obtained by numerical and statistical methods. For this aim, thermal performance of a WDASC is evaluated by finite element method (FEM) using FlexPDE commercial package software and Al2O3-water nanofluid is considered as the working fluid in the collector. It is considered that bottom wavy plate remain in a constant temperature while the top flat plate is in constant heat flux due to solar radiation and the sides wall are insulated. To find the best wavy profile for the bottom plate, 9 different cases proposed by CCD are designed and by response surface method (RSM) analysis the best profile is introduced. Results show that the best case involves minimum possible wave amplitude (Am) in average wave numbers (λ) for the wavy wall.
In this paper, thermal performance of a wavy nanofluid-based direct absorption solar collector (DASC) is evaluated using finite element method (FEM) by FlexPDE commercial package software. After ...presenting the governing equations and solving them by FEM, TiO2, Al2O3 and CuO nanoparticles are considered to make water-based nanofluid in the collector. Due to three different wall types in the problem (bottom wavy wall, flat top wall and vertical side walls) and three different boundary condition types (insulated, constant heat flux and constant temperature), the problem is solved for the more appropriate conditions. For all tested nanofluids, the effect of nanoparticles volume fraction is also investigated on the local/average Nusselt numbers. Results show that wavy collectors have larger maximum Nusselt number compared to flat plate collectors. Furthermore, the most Nusselt numbers are reported for TiO2 nanoparticles in the little volume fractions.
•Wavy wall and flat plate solar collector's performance are compared.•TiO2, Al2O3 and CuO-water nanofluids are considered as the working fluids.•Wavy wall collector has smaller average Nusselt and greater local Nusselt numbers.•TiO2-water nanofluid in smaller volume fractions had larger Nusselt number.
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•Virtual asphalt and 3D printing are used to understand clogging of asphalt mixture.•Clogging of asphalt is controlled by pore size and grading of the clogging particles.•Porosity’s ...tortuosity and connectivity are not related to the clogging of asphalt.•To minimise clogging, the pores in asphalt must be bigger than the clogging particles.
This paper investigates the effect of air void topology on the clogging properties of asphalt mixtures with porosity in the range 13.6%–31.8%. The air void properties of the asphalt mixtures were quantified by means of computed tomography of the asphalt. In addition, virtual pore networks were generated using the Intersected Stacked Air voids (ISA) method and then, 3D printed using transparent resin. The porous asphalt and the transparent resin with realistic pores were clogged by letting water and dust pass through the pores during hydraulic conductivity tests. The clogging ratio was measured by quantifying the reduction in hydraulic conductivity after each clogging cycle. The volume of pores clogged was quantified by means of thresholded images of the transparent resin with realistic pores. Furthermore, the clogging ratio of each test specimen was compared against its air void topologies, such as average pore diameter, tortuosity, Euler number, and macroporosity. It was found that the main factor influencing the clogging ratio of asphalt mixture was the air void diameter and the reason for this, is because particles of similar size to the pores have a high chance to block them. Tortuosity, Euler number, and macroporosity, do not have a significant influence on the clogging ratio of asphalt mixture. Finally, it was concluded that to build mixtures that do not clog, the size distribution of the clogging particles must be analysed prior to building the road and the maximum aggregate size and gradation carefully selected to produce pores which are bigger than the clogging particles.
To date, attempts to regenerate functional periodontal tissues (including cementum) are largely unsuccessful due to a lack of full understanding about the cellular origin (epithelial or mesenchymal ...cells) essential for root cementum growth. To address this issue, we first identified a rapid cementum growth window from the ages of postnatal day 28 (P28) to P56. Next, we showed that expression patterns of Axin2 and β-catenin within cementum-forming periodontal ligament (PDL) cells are negatively associated with rapid cementum growth. Furthermore, cell lineage tracing studies revealed that the Axin2+-mesenchymal PDL cells and their progeny rapidly expand and directly contribute to postnatal acellular and cellular cementum growth. In contrast, the number of K14+ epithelial cells, which were initially active at early stages of development, was reduced during rapid cementum formation from P28 to P56. The in vivo cell ablation of these Axin2+ cells using Axin2CreERT2/+; R26RDTA/+ mice led to severe cementum hypoplasia, whereas constitutive activation of β-catenin in the Axin2+ cells resulted in an acceleration in cellular cementogenesis plus a transition from acellular cementum to cellular cementum. Thus, we conclude that Axin2+-mesenchymal PDL cells, instead of K14+ epithelial cells, significantly contribute to rapid cementum growth.
In this paper, numerical Galerkin Finite Element Method (GFEM) is applied for conjugate heat-transfer of a rotating cylinder immersed in Fe
O
-water nanofluid under the heat-flux and magnetic field. ...The outer boundaries of the cavity were maintained at low temperatures while beside the cylinder were insulated. It is assumed that the cylinder rotates in both clockwise and counter-clockwise directions. The dimensionless governing equations such as velocity, pressure, and temperature formulation were analyzed by the GFEM. The results were evaluated using the governing parameters such as nanoparticles (NPs) volume fraction, Hartmann and Rayleigh numbers, magnetic field angle and NPs shapes. As a main result, the average Nusselt number increases by increasing the NPs volume fraction, inclination angle and thermal conductivity ratios, while increasing the Hartmann number decreased the Nusselt number. Furthermore, platelet NPs had the maximum average Nusselt number and spherical NPs made the minimum values of Nusselt numbers among examined NPs shapes.
Opaqueness of animal tissue can be attributed mostly to light absorption and light scattering. In most noncleared tissue samples, confocal images can be acquired at no more than a 100-µm depth. ...Tissue-clearing techniques have emerged in recent years in the neuroscience field. Many tissue-clearing methods have been developed, and they all follow similar working principles. During the tissue-clearing process, chemical or physical treatments are applied to remove components blocking or scattering the light. Finally, samples are immersed in a designated clearing medium to achieve a uniform refractive index and to gain transparency. Once the transparency is reached, images can be acquired even at several millimeters of depth with high resolution. Tissue clearing has become an essential tool for neuroscientists to investigate the neural connectome or to analyze spatial information of various types of brain cells. Other than neural science research, tissue-clearing techniques also have applications for bone research. Several methods have been developed for clearing bones. Clearing treatment enables 3-dimensional imaging of bones without sectioning and provides important new insights that are difficult or impossible to acquire with conventional approaches. Application of tissue-clearing technique on dental research remains limited. This review will provide an overview of the recent literature related to the methods and application of various tissue-clearing methods. The following aspects will be covered: general principles for the tissue-clearing technique, current available methods for clearing bones and teeth, general principles of 3-dimensional imaging acquisition and data processing, applications of tissue clearing on studying biological processes within bones and teeth, and future directions for 3-dimensional imaging.
Drosophila lacks C20 and C22 PUFAs Shen, Li Rong; Lai, Chao Qiang; Feng, Xiang ...
Journal of lipid research,
10/2010, Letnik:
51, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Drosophila melanogaster has been considered a model organism for investigating human diseases and genetic pathways. Whether Drosophila is an ideal model for nutrigenomics, especially for FA ...metabolism, however, remains to be illustrated. The aim of this study was to examine the metabolism of C20 and C22 PUFAs in Drosophila. Analysis of FA composition revealed a complete lack of C20 and C22 PUFAs in the body tissue of larvae, pupae, and adult flies fed either a base or supplemented diet abundant in the PUFA precursors linoleic acid and α-linolenic acid. PUFA with >C20 could only be found in flies supplemented with specific FAs. Interestingly, the supplemented C22 PUFAs docosahexaenoic acid (22:6n-3) and docosatetraenoic acid (22:4n-6) were largely converted to the shorter chain C20 PUFAs eicosapentaenoic acid (20:5n-3) and arachidonic acid (20:4n-6), respectively. Furthermore, a genome sequence scan indicated that no gene encoding Δ-6/ Δ-5 desaturases, the key enzymes for the synthesis of C20/C22 PUFA, was present in Drosophila. These findings demonstrate that Drosophila lacks the capability to synthesize the biologically important C20 and C22 PUFAs, and thereby argue that Drosophila is not a valid model for the study of lipid metabolism and related diseases.
Summary
The effects of exogenous pulsed electromagnetic field (PEMF) stimulation on T1DM-associated osteopathy were investigated in alloxan-treated rabbits. We found that PEMF improved bone ...architecture, mechanical properties, and porous titanium (pTi) osseointegration by promoting bone anabolism through a canonical Wnt/β-catenin signaling-associated mechanism, and revealed the clinical potential of PEMF stimulation for the treatment of T1DM-associated bone complications.
Introduction
Type 1 diabetes mellitus (T1DM) is associated with deteriorated bone architecture and impaired osseous healing potential; nonetheless, effective methods for resisting T1DM-associated osteopenia/osteoporosis and promoting bone defect/fracture healing are still lacking. PEMF, as a safe and noninvasive method, have proven to be effective for promoting osteogenesis, whereas the potential effects of PEMF on T1DM osteopathy remain poorly understood.
Methods
We herein investigated the effects of PEMF stimulation on bone architecture, mechanical properties, bone turnover, and its potential molecular mechanisms in alloxan-treated diabetic rabbits. We also developed novel nontoxic Ti2448 pTi implants with closer elastic modulus with natural bone and investigated the impacts of PEMF on pTi osseointegration for T1DM bone-defect repair.
Results
The deteriorations of cancellous and cortical bone architecture and tissue-level mechanical strength were attenuated by 8-week PEMF stimulation. PEMF also promoted osseointegration and stimulated more adequate bone ingrowths into the pore spaces of pTi in T1DM long-bone defects. Moreover, T1DM-associated reduction of bone formation was significantly attenuated by PEMF, whereas PEMF exerted no impacts on bone resorption. We also found PEMF-induced activation of osteoblastogenesis-related Wnt/β-catenin signaling in T1DM skeletons, but PEMF did not alter osteoclastogenesis-associated RANKL/RANK signaling gene expression.
Conclusion
We reveal that PEMF improved bone architecture, mechanical properties, and pTi osseointegration by promoting bone anabolism through a canonical Wnt/β-catenin signaling-associated mechanism. This study enriches our basic knowledge for understanding skeletal sensitivity in response to external electromagnetic signals, and also opens new treatment alternatives for T1DM-associated osteopenia/osteoporosis and osseous defects in an easy and highly efficient manner.
In this paper, thermal performance of a nanofluid in an inclined direct absorption solar collector (IDASC) is evaluated using a hybrid of finite difference method (FDM) and Differential ...Transformation Method (DTM) called Hybrid FDM-DTM. After presenting the governing equations and solving by hybrid method, the accuracy of results is examined by fourth order Runge-kutta numerical method. Alumina/water nanofluid is considered as the working fluid in the collector and two boundary conditions are defined for the collector base; a constant temperature and convection heat transfer. The second condition leads to insulated base when the coefficient is assumed to be zero. For both boundary conditions, the problem is analyzed and collector efficiency is calculated. Results confirm that to reach an efficient collector, nanoparticles volume fraction, convection coefficient and base temperature should be considered in maximum possible values.
•Thermal performances of solar collectors are evaluated.•Nanofluid based direct absorption solar collectors are modeled.•FDM-DTM hybrid method is used to solve the equations.•Collector's efficiency is calculated for different boundary conditions.
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