2,092 research outputs found

    When MHD-Based Microfluidics is Equivalent to Pressure-Driven Flow

    Get PDF
    Magnetohydrodynamics (MHD) provides a convenient, programmable means for propelling liquids and controlling fluid flow in microfluidic devices without a need for mechanical pumps and valves. When the magnetic field is uniform and the electric field in the electrolyte solution is confined to a plane that is perpendicular to the direction of the magnetic field, the Lorentz body force is irrotational and one can define a “Lorentz” potential. Since the MHD-induced flow field under these circumstances is identical to that of pressure-driven flow, one can utilize the large available body of knowledge about pressure-driven flows to predict MHD flows and infer MHD flow patterns. In this note, we prove the equivalence between MHD flows and pressure-driven flows under certain conditions other than flow in straight conduits with rectangular cross-sections. We determine the velocity profile and the efficiency of MHD pumps, accounting for current transport in the electrolyte solutions. Then, we demonstrate how data available for pressure driven flow can be utilized to study various MHD flows, in particular, in a conduit patterned with pillars such as may be useful for liquid chromatography and chemical reactors. Additionally, we examine the effect of interior obstacles on the electric current flow in the conduit and show the existence of a particular pillar geometry that maximizes the current

    The Somatization of Depression in Native Pakistani Women

    Get PDF
    Previous studies have pointed out the comorbidity of somatization and depression among non-Western psychiatric patients. We studied the somatization of depression in Pakistani women. Two groups were studies: inpatients with DSM-III-R diagnoses of major depression and a comparison sample of women living in the community without psychiatric diagnoses. Both groups were administered a rating scale for somatization. Results indicated that patients reported significantly more somatic symptoms than nonpatients. These findings support the concept that somatization may be a cultural mode of mental distress among Pakistani women, as has been observed for other non-Western populations

    Targeted expression profiling reveals distinct stages of early canine fibroblast reprogramming are regulated by 2-oxoglutarate hydroxylases

    Get PDF
    Background: Ectopic expression of a defined set of transcription factors allows the reprogramming of mammalian somatic cells to pluripotency. Despite continuous progress in primate and rodent reprogramming, limited attention has been paid to cell reprogramming in domestic and companion species. Previous studies attempting to reprogram canine cells have mostly assessed a small number of presumptive canine induced pluripotent stem cell (iPSC) lines for generic pluripotency attributes. However, why canine cell reprogramming remains extremely inefficient is poorly understood. Methods: To better characterize the initial steps of pluripotency induction in canine somatic cells, we optimized an experimental system where canine fetal fibroblasts (cFFs) are transduced with the Yamanaka reprogramming factors by Sendai virus vectors. We use quantitative PCR arrays to measure the expression of 80 target genes at various stages of canine cell reprogramming. We ask how cFF reprogramming is influenced by small molecules affecting the epigenomic modification 5-hydroxymethylcytosine, specifically L-ascorbic acid and retinoic acid (AA/RA). Results: We found that the expression and catalytic output of a class of 2-oxoglutarate-dependent (2-OG) hydroxylases, known as ten-eleven translocation (TET) enzymes, can be modulated in canine cells treated with AA/RA. We further show that AA/RA treatment induces TET1 expression and facilitates early canine reprogramming, evidenced by upregulation of epithelial and pluripotency markers. Using a chemical inhibitor of 2-OG hydroxylases, we demonstrate that 2-OG hydroxylase activity regulates the expression of a subset of genes involved in mesenchymal-to-epithelial transition (MET) and pluripotency in early canine reprogramming. We identify a set of transcription factors depleted in maturing reprogramming intermediates compared to pluripotent canine embryonic stem cells. Conclusions: Our findings highlight 2-OG hydroxylases have evolutionarily conserved and divergent functions regulating the early reprogramming of canine somatic cells and show reprogramming conditions can be rationally optimized for the generation of maturing canine iPSC

    Synchronization of Micromechanical Oscillators Using Light

    Get PDF
    Synchronization, the emergence of spontaneous order in coupled systems, is of fundamental importance in both physical and biological systems. We demonstrate the synchronization of two dissimilar silicon nitride micromechanical oscillators, that are spaced apart by a few hundred nanometers and are coupled through optical radiation field. The tunability of the optical coupling between the oscillators enables one to externally control the dynamics and switch between coupled and individual oscillation states. These results pave a path towards reconfigurable massive synchronized oscillator networks

    Development of Nanocomposite Coatings

    Get PDF
    Special Issue in the Development of Nanocomposite Coatings in nanomaterials was setup with the aim to provide an opportunity to showcase the latest developments within the theme of this special issue. It therefore welcomed research articles and reviews papers, by invitation only, within the context of nanocom-posite coatings for possible publications. There are wide ranging major applications of nanocomposite coat-ings for example corrosion, tribology, machine elements, components, complex interacting systems, and flu-id flow especially within the context of cavitation. We have been witnessing increased application needs to address key global and industrial challenges including energy efficiency, reliability, sustainability and dura-bility of systems and machines. These components and systems are often deployed in harsh operating envi-ronments and conditions, for example, very high and subzero temperatures, extreme pressures, very high loading, exposure to corrosive environment, and starved lubrication. To solve these issues, novel and inno-vative approaches are needed. These solutions include optimisation of surfaces and interfaces through surface modifications and coatings. Development and applications of nanocoatings and nanocomposite coatings are relatively new and developments in this area are underway

    Environmental friendly method for the extraction of cellulose from Triflolium resopinatum and its characterization

    Get PDF
    The leaves of Triflolium resopinatum were collected from the mountains of Malakand division, Khyber Pukhtoonkhwa, Pakistan and was grinded into smaller particles and converted into powder. The ground biomass was treated with different solvents in the Soxhlet apparatus for the removal of soluble extractive like pectin, cutin and wax substances. For bond breaking the alkaline substance was kept in the autoclave. Ethylene diamine tetra-acetate (EDTA) and hydrogen peroxide (H2O2) were used for the removal of most polar substances like pectin, cutin, waxes and other extractives. Furthermore, raw cellulose was purified through acetic acid and nitric acid. Double distilled water was used for the neutralization of pH.The analysis of purified cellulose was carried out through different procedures such as X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The extracted cellulose has high degree of purity and crystallinity (72%) and thermal stability indicating that the process for the extraction of cellulose is quite adequate.               KEY WORDS: Triflolium resopinatum, Cellulose, FTIR, XRD, TGA, SEM Bull. Chem. Soc. Ethiop. 2019, 33(1), 61-68DOI: https://dx.doi.org/10.4314/bcse.v33i1.

    Recycling of Spent Mushroom Substrate for the Production of Oyster Mushroom

    Get PDF
    The huge amount of spent mushroom substrate (SMS) was disposed, especially around the mushroom cultivation complexes. The present study aimed at utilizing this SMS in a productive and sustainable way. Experiment was carried out to reuse of SMS of oyster mushroom for the production of oyster mushroom at Bangladesh Agricultural University (BAU), Mymensingh. Two mushroom species (Pleurotus ostreatus and P. florida) were grown on SMS supplemented with sawdust and wheat bran at different proportions. The results showed that SMS supplement with 60% sawdust + 20% wheat bran demonstrated the highest biological yield, economic yield and biological efficiency for both P. ostreatus and P. florida. Yield parameters were increased with increasing C/N ratio where as 36:1 C/N ratio exhibited the highest yield. The C/N ratio below or above 36:1 decreased yield of both species of oyster mushroom. The optimum C/N ratio for economic yield varied between the two oyster mushroom species and found to be 35.2 for P. ostreatus against C/N ratio of 40.1 for P. florida. Concerning biological yield and biological efficiency the optimum C/N ratio was found 35.7 for P. Ostreatus and 40.6 for P. florida. The study emphatically indicated that reuse of spent mushroom substrate with supplementation can be a good solution to address the disposal problem where as supplemented SMS can be a good substrate for further mushroom production
    corecore