Numerical investigation of Al2O3/water nanofluid laminar convective heat transfer through triangular ducts

In this article, laminar flow-forced convective heat transfer of Al2O3/water nanofluid in a triangular duct under constant wall temperature condition is investigated numerically. In this investigation, the effects of parameters, such as nanoparticles diameter, concentration, and Reynolds number on the enhancement of nanofluids heat transfer is studied. Besides, the comparison between nanofluid and pure fluid heat transfer is achieved in this article. Sometimes, because of pressure drop limitations, the need for non-circular ducts arises in many heat transfer applications. The low heat transfer rate of non-circular ducts is one the limitations of these systems, and utilization of nanofluid instead of pure fluid because of its potential to increase heat transfer of system can compensate this problem. In this article, for considering the presence of nanoparticl: es, the dispersion model is used. Numerical results represent an enhancement of heat transfer of fluid associated with changing to the suspension of nanometer-sized particles in the triangular duct. The results of the present model indicate that the nanofluid Nusselt number increases with increasing concentration of nanoparticles and decreasing diameter. Also, the enhancement of the fluid heat transfer becomes better at high Re in laminar flow with the addition of nanoparticles

A Novel Dual-Membranes WGS Reactor with Palladium Alloy and Polyvinyl Alcohol Membranes for Enhanced Hydrogen Recovery

A novel membrane reactor concept including palladium alloy membrane (selective to H2) and polyvinyl alcohol membrane (selective to CO2) is proposed for water gas shift reaction. The mathematical model of the reactor is developed for two reactor schemes, namely plug dual-membrane reactor (PDMR) and CSTR dual-membrane reactor (CDMR) with uni-dimensional and non-isothermal conditions. A comparison between PDMR and palladium alloy membrane reactor (PAMR) showed that PDMR volume becomes 30 % less than PAMR with 20 bar increase in feed pressure. Then the effect of Damkholer number, feed composition, and feed pressure on hydrogen recovery and CO conversion for PDMR and CDMR has been studied. Under the same operating conditions, CO conversion in PDMR is 10 % more than CDMR while its temperature decreases. The new proposed reactor configuration could pave the way for simultaneous production of hydrogen, increased CO conversion, and CO2 separation on an industrial scale

Potential of heat pipe technology in nuclear seawater desalination

The official published version of this article can be found at the link below.Heat pipe technology may play a decisive role in improving the overall economics, and public perception on nuclear desalination, specifically on seawater desalination. When coupled to the Low-Temperature Multi-Effect Distillation process, heat pipes could effectively harness most of the waste heat generated in various types of nuclear power reactors. Indeed, the potential application of heat pipes could be seen as a viable option to nuclear seawater desalination where the efficiency to harness waste heat might not only be enhanced to produce larger quantities of potable water, but also to reduce the environmental impact of nuclear desalination process. Furthermore, the use of heat pipe-based heat recovery systems in desalination plant may improve the overall thermodynamics of the desalination process, as well as help to ensure that the product water is free from any contamination which occur under normal process, thus preventing operational failure occurrences as this would add an extra loop preventing direct contact between radiation and the produced water. In this paper, a new concept for nuclear desalination system based on heat pipe technology is introduced and the anticipated reduction in the tritium level resulting from the use of heat pipe systems is discussed

Targeting Cancer Stem Cells: A Solution to Cancer Therapy

Over the past several decades, accelerating scientific and technological advances have enabled researchers to make a great quantity of knowledge in the field of cancer biology. Numerous genes, mutant alleles, proteins, and signalling networks involved in the initiation and progression of cancer have been identified and some of the mechanisms deliberating resistance to therapy. Because of the limited efficacy of presently available treatment modalities, the cancer results to death and distress. One of the most important and complicated topics about the cancer is cancer stem cells (CSCs). The CSCs are immortal tumor-initiating cells that share some characteristics with normal stem/progenitor cells. Some of their important characteristics are self-renewal and multilineage differentiation. Since CSCs have potential resistance to chemotherapeutic agents as well as radiation therapy, it makes a serious challenge for current cancer treatments. There are various strategies for eradicating CSCs. Targeting of CSCs usually occurs by pharmacological targeting, immunotherapy and genetic targeting (miRNA,oncolytic virus). More recently, nanomedicine considerably extends the anticancer drugs, treatment strategies, and targeting CSCs. In this field, all currently available strategies could be divided into three major sections: Drug delivery targeting CSCs (nanocarriers such as nanoparticles (NPs), liposomes, micelles, nanotubes and nanogels), targeting genes of drug resistance and destruction the CSCs niches. In this review, we discussed some characteristics of CSCs and their therapeutic strategies

Experimental Investigation of nanofluid heat transfer in a square cross-sectional duct

English version Forced convective heat transfer of two different nanofluids including AL$_2$O$_3$-water and CuO-water in laminar flow through square cross section duct under constant heat flux has been investigated. The Nusselt number and average convective heat transfer coefficient for different nanoparticles concentrations as a function of Peclet number have been analyzed. AL$_2$O$_3$-water nanofluid with 0.2, 0.5, 1.0, 1.5, 2.0 and 2.5 percent volume fractions has been tested. The maximum enhancement of convective heat transfer coefficient for each of the above mentioned concentrations was 7, 10, 13, 18, 22, 27 percent, respectively. Also, CuO-water nanofluid was tested at 0.1, 0.2, 0.5, 0.8, 1.0 and 1.5 percent volume fractions and the results show that the maximum enhancement of convective heat transfer coefficient for each concentration was 8, 10, 14, 16, 19, 21 percent, respectively.Comment: 6 pages, in Persia

MicroRNAs as Biomarkers for Early Diagnosis, Prognosis, and Therapeutic Targeting of Ovarian Cancer

Ovarian cancer is the major cause of gynecologic cancer-related mortality. Regardless of outstanding advances, which have been made for improving the prognosis, diagnosis, and treatment of ovarian cancer, the majority of the patients will die of the disease. Late-stage diagnosis and the occurrence of recurrent cancer after treatment are the most important causes of the high mortality rate observed in ovarian cancer patients. Unraveling the molecular mechanisms involved in the pathogenesis of ovarian cancer may help find new biomarkers and therapeutic targets for ovarian cancer. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression, mostly at the posttranscriptional stage, through binding to mRNA targets and inducing translational repression or degradation of target via the RNA-induced silencing complex. Over the last two decades, the role of miRNAs in the pathogenesis of various human cancers, including ovarian cancer, has been documented in multiple studies. Consequently, these small RNAs could be considered as reliable markers for prognosis and early diagnosis. Furthermore, given the function of miRNAs in various cellular pathways, including cell survival and differentiation, targeting miRNAs could be an interesting approach for the treatment of human cancers. Here, we review our current understanding of the most updated role of the important dysregulation of miRNAs and their roles in the progression and metastasis of ovarian cancer. Furthermore, we meticulously discuss the significance of miRNAs as prognostic and diagnostic markers. Lastly, we mention the opportunities and the efforts made for targeting ovarian cancer through inhibition and/or stimulation of the miRNAs

Visualization study on the instabilities of phase-change heat transfer in a flat two-phase closed thermosyphon

This paper presents systematic experiments and visualization on the instabilities of phase-change heat transfer for water, ethanol and acetone in a flat evaporator of a two phase closed system, respectively. The effects of the heat flux, filling ratio, coolant temperature and working fluid type on the instabilities and their mechanisms have been systematically investigated. The experimental results show that the instabilities of phase-change heat transfer are strongly related to the corresponding heat transfer modes. The instabilities of temperature and heat transfer coefficient (HTC) of the evaporator are mainly caused by the bubble behaviours, the physical properties and the operation pressures. Natural convection, intermittent boiling and fully developed nucleate boiling are the main heat transfer modes in the present study. The condensate droplets may affect the instabilities due to inducing periodic boiling at lower heat fluxes. The maximum standard deviations of the evaporator temperature and vapor pressure fluctuations can reach 3.1 °C and 0.8 kPa respectively during the intermittent boiling. There is no intermittent boiling regime for ethanol and acetone in the present study. Therefore, no instability phenomena of nucleate boiling with ethanol and acetone are observed in the present study