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Analysis of the Condensate Carryover Phenomenon on Fin and Tube Evaporators
Emilio Navarro-Peris,Jose Miguel Corberan,Jose Gonzalvez,Miguel Zamora 대한설비공학회 2015 International Journal Of Air-Conditioning and Refr Vol.23 No.1
Possible carryover of the condensate from the surface of the evaporator has always been aproblem that in practice has been solved by limiting the air velocity. However, the need for morecompact solutions and especially for the reduction of the frontal area in many applicationsrequires the increase of the air velocity and therefore new solutions to overcome this problemmust be developed. In this contribution, the authors develop an analytical model to estimate theevolution of the condensing drops over the ¯n surface of a heat exchanger as a function of the ¯nsurface properties and air velocity. This model allows the estimation of the drop size when itstarts to move and its trajectory and evolution along the ¯n. The possibility of drops formingwater bridges in between the ¯ns is also analyzed with estimation of the minimum ¯n separationto avoid its formation depending on the air velocity and the wettability of the ¯n surface. Finally,the results of an experimental campaign performed with two ¯n and tube coils of exactly samedimensions and geometry but with di®erent ¯n materials: one with the standard aluminum ¯nand the other one with a specially outer hydrophilic layer, are presented, showing that this kindof coating avoids the condensate carryover with no appreciable penalty on the heat transferperformance.
Evert Meijers,Antoine Peris 서울시립대학교 도시과학연구원 2019 도시과학국제저널 Vol.23 No.2
While there is consensus that network embeddedness of cities is of great importance for their development, the precise effect is difficult to assess because of a lack of consistent information on relations between cities. This paper presents, applies and evaluates a rather novel method to establish the strength of relationships between places, a method we refer to as ‘the toponym co-occurrence method’. This approach builds the urban system on the basis of co-occurrences of place names in a text corpus. We innovate by exploiting a so far unparalleled amount of data, namely the billions of web pages contained in the commoncrawl web archive, and by applying the method also to small places that tend to be ignored by other methods. The entire settlement system of the Netherlands is consequently explored. In addition, we innovatively apply machine learning techniques to classify these relations. Much attention is paid to solving biases deriving from place name disambiguation. Gravity modelling is employed to assess the resulting spatial organization of the Netherlands. It turns out that the gravity model fits very well with the pattern of relationships between places as found in digital space, which contributes to our assessment that the toponym co-occurrence method is a solid proxy for relationships in real space. Using the method, it is established that the relationships in the Randstad region, by many considered a coherent metropolitan entity, are actually somewhat less strong than expected. In contrast, historically important, but nowadays small cities in the periphery tend to have maintained their prominent position in the pattern of relationships. Suburban, relatively new places in the shadow of a larger city tend to be weakly related to other places. Several suggestions to further improve the method, in particular the classification of relationships, are discussed.
Pherah A. Ouma,Victoria K. Mwaeni,Peris W. Amwayi,Alfred Orina Isaac,James Nyabuga Nyariki 한국실험동물학회 2022 Laboratory Animal Research Vol.38 No.3
Background: Calcium carbide (CaC2) is a chemical primarily used in the production of acetylene gas. The misuse of CaC2 to induce fruit ripening is a global challenge with a potential adverse effects to human health. Additionally, CaC2 is known to contain some reasonable amount of arsenic and phosphorous compounds that are toxic and pose a danger to human health when ingested. The current study sought to characterize CaC2 toxicity and elucidate any protective effects by cyanocobalamin (vitamin B12), a well-established antioxidant and anti-inflammatory bio-molecule. Female Swiss white mice were randomly assigned into three groups; the first group was the control, while the second group was administered with CaC2. The third group received CaC2 followed by administration of vitamin B12. The mice were sacrificed at 60 days post treatment, hematological, biochemical, glutathione assay, cytokine ELISA and standard histopathology was performed. Results: CaC2 administration did not significantly alter the mice body weight. CaC2 administration resulted in a significant decrease in packed cell volume (PCV), hemoglobin (Hb), red blood cells (RBCs) and RBC indices; indicative of CaC2-driven normochromic microcytic anaemia. Further analysis showed CaC2-driven leukopenia. Evidently, vitamin B12 blocked CaC2-driven suppression of PCV, Hb, RBCs and WBCs. Monocytes and neutrophils were significantly upregulated by CaC2. CaC2-induced elevation of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and bilirubin signaled significant liver damage. Notably, vitamin B12 stabilized AST, ALT and bilirubin in the presence of CaC2, an indication of a protective effect. Histopathological analysis depicted that vitamin B12 ameliorated CaC2-driven liver and kidney injury. CaC2 resulted in the depletion of glutathione (GSH) levels in the liver; while in the brain, kidney and lungs, the GSH levels were elevated. CaC2 administration resulted in elevation of pro-inflammatory cytokines TNF-α and IFN-γ. Vitamin B12 assuaged the CaC2-induced elevation of these pro-inflammatory cytokines. Conclusions: These findings demonstrate for the first time that oral supplementation with vitamin B12 can protect mice against CaC2-mediated toxicity, inflammation and oxidative stress. The findings provide vital tools for forensic and diagnostic indicators for harmful CaC2 exposure; while providing useful insights into how vitamin B12 can be explored further as an adjunct therapy for CaC2 toxicity.
A Murine Model for Human Sepiapterin-Reductase Deficiency
Yang, Seungkyoung,Lee, Young Jae,Kim, Jin-Man,Park, Sean,Peris, Joanna,Laipis, Philip,Park, Young Shik,Chung, Jae Hoon,Oh, S. Paul University of Chicago Press [etc.] 2006 American journal of human genetics Vol.78 No.4
<P>Tetrahydrobiopterin (BH<SUB>4</SUB>) is an essential cofactor for several enzymes, including all three forms of nitric oxide synthases, the three aromatic hydroxylases, and glyceryl-ether mono-oxygenase. A proper level of BH<SUB>4</SUB> is, therefore, necessary for the metabolism of phenylalanine and the production of nitric oxide, catecholamines, and serotonin. BH<SUB>4</SUB> deficiency has been shown to be closely associated with diverse neurological psychiatric disorders. Sepiapterin reductase (SPR) is an enzyme that catalyzes the final step of BH<SUB>4</SUB> biosynthesis. Whereas the number of cases of neuropsychological disorders resulting from deficiencies of other catalytic enzymes involved in BH<SUB>4</SUB> biosynthesis and metabolism has been increasing, only a handful of cases of SPR deficiency have been reported, and the role of SPR in BH<SUB>4</SUB> biosynthesis in vivo has been poorly understood. Here, we report that mice deficient in the <I>Spr</I> gene (<I>Spr</I><SUP>−/−</SUP>) display disturbed pterin profiles and greatly diminished levels of dopamine, norepinephrine, and serotonin, indicating that SPR is essential for homeostasis of BH<SUB>4</SUB> and for the normal functions of BH<SUB>4</SUB>-dependent enzymes. The <I>Spr</I><SUP>−/−</SUP> mice exhibit phenylketonuria, dwarfism, and impaired body movement. Oral supplementation of BH<SUB>4</SUB> and neurotransmitter precursors completely rescued dwarfism and phenylalanine metabolism. The biochemical and behavioral characteristics of <I>Spr</I><SUP>−/−</SUP> mice share striking similarities with the symptoms observed in SPR-deficient patients. This <I>Spr</I> mutant strain of mice will be an invaluable resource to elucidate many important issues regarding SPR and BH<SUB>4</SUB> deficiencies.</P>
The marine <i>kd</i> and water/sediment interaction problem
Periá,ñ,ez, R.,Brovchenko, I.,Jung, K.T.,Kim, K.O.,Maderich, V. Elsevier 2018 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.192 No.-
<P><B>Abstract</B></P> <P>The behavior of marine distribution coefficients is analyzed with the help of numerical experiments and analytical solutions of equations describing kinetic models for uptake/release of radionuclides. The difficulties in measuring true k<SUB>d</SUB> in a marine environment perturbed by an external radionuclide source are highlighted. Differences between suspended matter and bed sediment k<SUB>d</SUB> are analyzed. The performances of different kinetic models (1-step/2step; single-layer/multi-layer) are studied in model/model and model/experiment comparisons. Implications for the use of models to assess radioactive contamination after an emergency are given; as well as recommendations when k<SUB>d</SUB> data are compiled in order to create a useful database.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Equilibrium in radionuclide partition between water and sediment seldom found in the sea. </LI> <LI> Differences between suspended matter and bed sediment kd highlighted. </LI> <LI> One step and two step kinetic models performances compared. </LI> <LI> Single layer and multi-layer models compared. </LI> <LI> Formulation to deal with changes in salinity and pH provided. </LI> </UL> </P>