The osteoprotective effect of Herba epimedii (HEP) extract in vivo and in vitro

Herba epimedii (HEP) is one of the most frequently used herbs prescribed for treatment of osteoporosis in China. In the present study, the in vivo effects of HEP extract on bone metabolism were evaluated using 4-month-old ovariectomized (OVX) or sham-operated (Sham) female Sprague-Dawley rats orally administered with HEP extract (110 mg kg(−1)d(−1)), 17ß-estrogen (2 mg kg(−1)d(−1)) or its vehicle for 3 months. HEP extract significantly decreased urinary calcium excretion, suppressed serum alkaline phosphatase (ALP) activity and urinary deoxypyridinoline levels in OVX rats (P < 0.05 versus vehicle-treated OVX rats). Histomorphometric analysis indicated that HEP extract could prevent OVX-induced bone loss by increasing tibial trabecular bone area and decreasing trabecular separation in OVX rats (P < 0.05 versus vehicle-treated OVX group). The in vitro effects of HEP extract were also studied using rat osteoblast-like UMR 106 cells. HEP extract significantly stimulated cell proliferation in a dose-dependent manner (P < 0.01 versus vehicle-treated) and increased ALP activity at 200 μgml(−1) (P < 0.01 versus vehicle-treated) in UMR 106 cells. It modulated osteoclastogenesis by increasing osteoprotegrin (OPG) mRNA and decreasing receptor activator of NF-κB ligand (RANKL) mRNA expression, resulting in a dose-dependent increase in OPG/RANKL mRNA ratio (P < 0.01 versus vehicle-treated). Taken together, HEP treatment can effectively suppress the OVX-induced increase in bone turnover possibly by both an increase in osteoblastic activities and a decrease in osteoclastogenesis. The present study provides the evidence that HEP can be considered as a complementary and alternative medicine for treatment of post-menopausal osteoporosis

Symmetry and Topology in Superconductors - Odd-frequency pairing and edge states -

Superconductivity is a phenomenon where the macroscopic quantum coherence appears due to the pairing of electrons. This offers a fascinating arena to study the physics of broken gauge symmetry. However, the important symmetries in superconductors are not only the gauge invariance. Especially, the symmetry properties of the pairing, i.e., the parity and spin-singlet/spin-triplet, determine the physical properties of the superconducting state. Recently it has been recognized that there is the important third symmetry of the pair amplitude, i.e., even or odd parity with respect to the frequency. The conventional uniform superconducting states correspond to the even-frequency pairing, but the recent finding is that the odd-frequency pair amplitude arises in the spatially non-uniform situation quite ubiquitously. Especially, this is the case in the Andreev bound state (ABS) appearing at the surface/interface of the sample. The other important recent development is on the nontrivial topological aspects of superconductors. As the band insulators are classified by topological indices into (i) conventional insulator, (ii) quantum Hall insulator, and (iii) topological insulator, also are the gapped superconductors. The influence of the nontrivial topology of the bulk states appears as the edge or surface of the sample. In the superconductors, this leads to the formation of zero energy ABS (ZEABS). Therefore, the ABSs of the superconductors are the place where the symmetry and topology meet each other which offer the stage of rich physics. In this review, we discuss the physics of ABS from the viewpoint of the odd-frequency pairing, the topological bulk-edge correspondence, and the interplay of these two issues. It is described how the symmetry of the pairing and topological indices determines the absence/presence of the ZEABS, its energy dispersion, and properties as the Majorana fermions.Comment: 91 pages, 38 figures, Review article, references adde

On the spreading of viscous dense liquid under surface waves

abstractpublished_or_final_versiontocMechanical EngineeringMasterMaster of Philosoph

Performance analysis of a waste heat driven activated carbon based composite adsorbent - Water adsorption chiller using simulation model

This study aims at improving the performance of a waste heat driven adsorption chiller by applying a novel composite adsorbent which is synthesized from activated carbon impregnated by soaking in sodium silicate solution and then in calcium chloride solution. Modeling is performed to analyze the influence of the hot water inlet temperature, cooling water inlet temperature, chilled water inlet temperatures, and adsorption/desorption cycle time on the specific cooling power (SCP) and coefficient of performance (COP) of the chiller system with the composite adsorbent. The simulation calculation indicates a COP value of 0.65 with a driving source temperature of 85 °C in combination with coolant inlet and chilled water inlet temperature of 30 °C and 14 °C, respectively. The most optimum adsorption-desorption cycle time is approximately 360 s based on the performance from COP and SCP. The delivered chilled water temperature is about 9 °C under these operating conditions, achieving a SCP of 380 W/kg. © 2012 Elsevier Ltd. All rights reserved

Modeling a solar-powered double bed novel composite adsorbent (silica activated carbon/CaCl2)-water adsorption chiller

During the past few decades, the growing demand for air conditioning has caused a significant increase in demand for primary energy resources. Adsorption cooling system is one of the technologies which could be powered by renewable energy. This study aims to improve the performance of a solar-powered adsorption chiller by applying a novel composite adsorbent, a mixture of activated carbon, silica gel and calcium chloride. Modeling is established to investigate the cooling performance of a composite adsorbent based adsorption chiller driven by flat-type solar collectors with three different configurations of glaze: (1) single glazed cover; (2) double glazed cover and (3) transparent insulation material (TIM) cover. The simulation results show that the coefficient of performance (COP) and the specific cooling power (SCP) of the adsorption chiller depend hugely on the solar collector temperature. It is found that a double glazed cover shows the best cooling performance and 30 m(2) is the most optimized solar collector area. Two to three hours of pre-heating time is required to initiate the desorption process of the adsorber in a day of operation. This newly developed silica activated carbon/CaCl2 composite material as adsorbent used in the adsorption chiller could achieve a high mean COPsc of 0.48. Its satisfactory performance suggests that this novel composite material has a potential to be used in the adsorption chiller system even if it is powered by unstable solar energy

A Semi-analytical Model for the Thermal Conductivity of Nanofluid and Determination of the Nanolayer Thickness

Nanofluid shows a huge potential to be the next-generation heat transfer fluid since the nanoparticles can suspend in the base fluids for a long time and the thermal conductivity of the nanofluid can be far above those of convectional solid-liquid suspension. It has long been known that liquid molecules close to a solid surface can form a layer which is solid-like in structure, but little is known about the connection between this layer and the thermal properties of the suspension. In this study, a semi-analytical model for calculating the enhanced thermal conductivity of nanofluids is derived from the steady heat conduction equation in spherical coordinates. The effects of nanolayer thickness, nanoparticle size, volume fraction, thermal conductivity of nanoparticles and base fluid are discussed. A linear thermal conductivity profile inside the nanolayer is considered in the present model. The proposed model, while investigating the impact of the interfacial nanolayer on the effective thermal conductivity of nanofluids, provides an equation to determine its nanolayer thickness for different types of nanofluids. Hence, different relationships between the nanolayer thickness and the nanoparticle size are found for each type of nanofluid. Moreover, based on the present model's prediction, it is found that the effective thermal conductivities of nanofluids show the same result as the Maxwell model when the nanolayer thickness value approaches to zero. Lastly, the effective thermal conductivities of different types of nanofluids calculated by the present model is in good agreement with the experimental results and the prediction is much better than the Maxwell model and Bruggeman model. © 2013 Elsevier Ltd. All rights reserved

Comparison of the Resuspension Behavior Between Liquid and Solid Aerosols

Resuspension of an aerosol from solid surfaces is an important phenomenon. The resuspension behaviors of solid aerosols and liquid aerosols are not necessarily the same. A whole solid particle detaches from the surface when the removal force is sufficient, while a portion of a droplet may detach even if the removal force is insufficient to detach the whole droplet. The objective of this article is to compare the resuspension behaviors between liquid and solid aerosols from a solid surface. Polystyrene particles and glycerol in micron sizes were generated and deposited on substrates. Two types of experiments, centrifugal detachment and vibrational resuspension, were carried out. In the centrifuge experiment, a constant removal force field was provided. Larger droplets split into smaller portions during detachment. In terms of the fraction remaining, the adhesion of the liquid aerosol has the same order of magnitude to that of the solid particle. A theoretical analysis analogous to the case of pendent drop was carried out, and the theoretical prediction agreed well with the experimental result. In the vibration experiment, a sinusoidal force field was applied. A same fraction of the solid particle detached with a much smaller force in vibration experiment than in the centrifuge experiment, whereas no resuspension was observed for liquid droplets. The adhesive forces of the liquid and solid aerosols have the same order of magnitude in the centrifuge case, but in the vibration case their adhesive forces have much greater difference. It poses a necessity for further investigation