Study of carbon dioxide condensation in chevron plate exchangers; pressure drop analysis

Condensation pressure drop of carbon dioxide in brazed plate heat exchangers was investigated, and is presented in this paper. Carbon dioxide is known as an environmental friendly refrigerant with an Ozone Depletion Potential (ODP) equal to zero and Global Warming Potential (GWP) equal to unity, and has favorable thermodynamic and transport properties though it requires higher operating pressures (～15–30 bar). Brazed-type plate heat exchangers that can withstand high pressure are a good choice for such applications. This paper presents the procedure, data collection, and results for three brazed plate heat exchangers with different inner geometries. The test exchangers showed good performance at high system pressures with reasonable pressure drops (less than 8%). The collected experimental data that covered real world operating conditions are valuable for the design of cascade condensers with carbon dioxide as the low-side refrigerant.     

Technologies to recover exhaust heat from internal combustion engines

The focus of this study is to review the latest developments and technologies on waste heat recovery of exhaust gas from internal combustion engines (ICE). These include thermoelectric generators (TEG), organic Rankine cycle (ORC), six-stroke cycle IC engine and new developments on turbocharger technology. Furthermore, the study looked into the potential energy savings and performances of those technologies. The current worldwide trend of increasing energy demand in transportation sector are one of the many segments that is responsible for the growing share of fossil fuel usage and indirectly contribute to the release of harmful greenhouse gas (GHG) emissions. It is hoped that with the latest findings on exhaust heat recovery to increase the efficiency of ICEs, world energy demand on the depleting fossil fuel reserves would be reduced and hence the impact of global warming due to the GHG emissions would fade away.     

Cyclin D3 in the mouse uterus is associated with the decidualization process during early pregnancy

We study the impact of correlated neuronal firing rate variability on the accuracy with which an encoded quantity can be extracted from a population of neurons. Contrary to widespread belief, correlations in the variabilities of neuronal firing rates do not, in general, limit the increase in coding accuracy provided by using large populations of encoding neurons. Furthermore, in some cases, but not all, correlations improve the accuracy of a population code.     

Modified activated carbons with amino groups and their copper adsorption properties in aqueous solution

Activated carbons were prepared by two chemical methods and the adsorption of Cu (II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration, and pHzpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also, adsorption mechanism and effect of pH on the adsorption of Cu (II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu (II) ions is stronger than that with H+ions due to relatively higher divalent charge or stronger electrostatic force.     

Effects of 9-ene-tetrahydrocannabinol on expression of beta-type transforming growth factors, insulin-like growth factor-I and c-myc genes in the mouse uterus

Effects of cannabinoid on expression of beta-type transforming growth factors (TGF-beta 1, -beta 2 and -beta 3), insulin-like growth factor-I (IGF-I) and c-myc genes in the uteri of adult ovariectomized mice were examined using Northern blot hybridization. Mice were exposed to 9-ene-tetrahydrocannabinol (THC) alone or in combination with an injection of estradiol-17 beta (E2) and/or progesterone (P4), and uteri were analyzed at various times thereafter. TGF-beta isoform messenger RNAs (mRNAs) persisted in ovariectomized uteri and their levels were not altered after THC treatment, whereas an injection of E2 caused a modest increase in TGF-beta 1 and -beta 3 mRNA levels at 24 h. Imposition of THC treatment advanced the stimulatory effects of E2 by changing the timing for the peak of TGF-beta 3 mRNA levels to 12 h. In comparison, E2 treatment substantially elevated the levels of TGF-beta 2 mRNA at 6 h, and THC potentiated this E2 response without affecting the timing for the response. Imposition of P4 treatment did not antagonize any of these responses. P4 treatment alone or with THC had insignificant effects on mRNA levels for these TGF-beta isoforms. Uterine levels of IGF-I and c-myc mRNAs were low in ovariectomized mice and THC did not alter these mRNA levels. In contrast, E2 treatment induced a rapid, but transient, increase in IGF-I and c-myc mRNAs, and THC antagonized the rapid c-myc mRNA response and altered the timing of the IGF-I mRNA response. P4 treatment alone also caused the transient induction of these mRNAs, but THC failed to antagonize these effects. An injection of P4 plus E2 resulted in further modest increases in IGF-I and c-myc mRNA levels as compared to E2 or P4 treatment alone. However, THC did not antagonize these transient stimulatory effects of the combined ovarian steroids. The data suggest that THC should not be classified as estrogenic or antiestrogenic. However, this compound can modulate (potentiate, antagonize and/or alter timing) the effects of ovarian steroids on uterine gene expression.     

Monitoring autocorrelated multivariate simple linear profiles

Recently, many researchers and practitioners have shown interest on profile monitoring as a relatively new subarea of statistical process control. One main reason for this interest, and perhaps a key factor for the contributions of many researchers to this field, is the various applications of profile monitoring in real life. Although one can easily encounter many univariate applications of profile monitoring in service and manufacturing environments, there exist situations where quality of a product or process needs to be modeled in multivariate terms. In this paper, we investigate monitoring of multivariate simple linear profiles in phase II when independence assumption of observations within profile is violated. A remedial measure based on a transformation method is proposed to remove the autocorrelation structure within multivariate profiles, and numerical simulation is used as a vehicle to evaluate the effect of the proposed solution. Finally, a case study is considered to show the application of the model in practice.     

A comparative study of combustion performance and emission of biodiesel blends and diesel in an experimental boiler

Recently, biodiesel has become more attractive since it is made from renewable resources and also for the fact that the resources of fossil fuels are diminishing day by day. This study compares combustion of B5, B10, B20, B50, B80 and B100 with petroleum diesel over wide input air flows at two energy levels in an experimental boiler. The comparison is made in terms of combustion efficiency and flue gas emissions (CO, CO₂, NO_X, and SO₂) and influence of air flow at two energy levels 219 kJ/h and 249 kJ/h is studied. The findings show that at higher level energy diesel efficiency was a little higher than that of biodiesel, but at lower level biodiesels are efficient than diesel. Except B10, Biodiesel and other blends emitted less pollutant CO, SO₂ and CO₂ than diesel. B10 emitted lower CO₂ and NO_X, but emitted higher SO₂ than diesel. Despite studies reporting an increase in the NO_X level resulting from burning of biodiesel over conventional petroleum diesel fuels in engines, our findings indicated at the second energy level a reduction in the NO_X level in the flue gases resulting from burning of biodiesel.     

Effects of addition of bismuth oxide and glass on the properties of lithium ferrite for ferrimagnetic pastes

Lithium ferrite, Li_0.5Fe_2.5O₄, has been prepared by decomposition of organometallic complexes at 800° C, and the optimization of heating schedule for conversion into ferrite has been studied. The effects of addition of glass, essential for adhesion of the ferrite film to alumina substrates, and bismuth oxide, as a sintering aid, on the properties and densification of lithium ferrite have been examined. X-ray diffraction, electron probe micro analysis (EPMA) and scanning electron microscopy (SEM) techniques have been used to study the solubility and distribution of bismuth oxide, grain growth and pore morphology. It has been found that the addition of bismuth oxide (up to 1.5 wt%) improves densification and increases resistivity of the lithium ferrite but the addition of glass causes a reduction of the resistivity. Although bismuth oxide forms a solid solution, it is not uniformly distributed throughout the ferrite phase. It is shown that the addition of bismuth oxide improves the insertion loss in microwave devices fabricated using ferrimagnetic pastes.     

Catalytic Friedel–Crafts Acylation and Benzoylation of Aromatic Compounds Using Activated Hematite as a Novel Heterogeneous Catalyst

Catalytic Friedel–Crafts acylation of benzene and unactivated benzenes such as chlorobenzene and nitrobenzene have been successfully carried out using activated hematite (α‐Fe₂O₃) as a new, heterogeneous and green catalyst. Sonication of neat α‐Fe₂O₃ in a water bath under air atmosphere at room temperature followed by heating at 200 °C, dramatically increase the activity of α‐Fe₂O₃. With the catalyst loading as low as 5.0 mol%, a wide variety of benzene derivatives were easily converted into the corresponding acylated products in a clean and high‐yielding acylation reaction. It was found that the activated α‐Fe₂O₃ could be efficiently recycled and reused several times by simple washing with ethyl acetate, this cannot be attained with most of the traditional catalysts.     

Effects of cannabinoids on preimplantation mouse embryo development and implantation are mediated by brain-type cannabinoid receptors

We examined the relative importance of G (Gi) protein-coupled brain-type (CB1-R) and spleen-type (CB2-R) cannabinoid receptors in preimplantation embryo development using agonists and antagonists specific to CB1-R and CB2-R. The results establish that endogenous cannabinoid ligands, anandamide and sn-2 arachidonoylglycerol, arrest embryo development in vitro, and this effect is reversed by CB1-R antagonists SR141716A or AM 251, but not by SR144528, a CB2-R antagonist. A CB2-R selective agonist AM 663 failed to affect embryo development. These results suggest that cannabinoid effects on embryo development are mediated by CB1-R. We also observed that delta9-tetrahydrocannabinol ([-]THC) infused in the presence of cytochrome P450 inhibitors interfered with blastocyst implantation. This adverse effect was reversed by coinfusion of SR141716A. The less active stereoisomer (+)THC plus the inhibitors failed to affect implantation. Analysis of tissue levels demonstrated that uterine accumulation of (-)THC occurred when it was infused in the presence of the P450 inhibitors. These results demonstrate that the uterus and perhaps the embryo have the cytochrome P450 enzymes to metabolize (-)THC and neutralize its adverse effects on implantation. Collectively, the present study demonstrates that cannabinoid effects on embryo development and implantation are mediated by embryonic and/or uterine CB1-R, but not CB2-R.