436 research outputs found

    Potential Thermal Enhancement of Lightweight Building Walls Derived From Using Phase Change Materials (PCMs)

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    This work is licensed under a Creative Commons Attribution 4.0 International License.This paper presents results of the potential thermal enhancement in building walls derived from using phase change materials (PCMs). Typical North American construction, namely, frame walls outfitted with hydrated-salt-based PCM with a melting temperature of 29°C were evaluated in well-controlled test houses under full weather conditions. It was found that PCMs produced reductions in energy gains during summer. The reductions were assessed via total heat transfer and peak heat transfer. For a 10 percentage by weight (wt%) PCM concentration, the largest peak flux reduction of 31.25% was observed when the PCM was integrated within a north-facing wall. For a 20 wt% PCM concentration, the largest peak flux reduction was 25.54% when the PCM pipes was installed on an east-facing wall. Doubling the amount of PCM did not produce improvement on heat flux reduction except for the east-facing wall. The indoor wall surface temperature and temperature amplitude was reduced by 1.5 and 1.4°C, respectively. The maximum time lag for peak heat flux was observed on the north-facing wall, which was 1.5 h for a 10 wt% PCM concentration and 2.25 h for a 20 wt% PCM concentration, respectively. To achieve the maximum energy savings, it is recommended that the PCMs be installed within west-facing walls

    Quasi-unit regularity and QB-rings

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    Some relations for quasiunit regular rings and QB-rings, as well as for pseudounit regular rings and QB ∞-rings, are obtained. In the first part of the paper, we prove that (an exchange ring R is a QB-ring) ⟺ (whenever x ∈ R is regular, there exists a quasiunit regular element w ∈ R such that x = xyx = xyw for some y ∈ R) ⟺ (whenever aR + bR = dR in R; there exists a quasiunit regular element w ∈ R such that a + bz = dw for some z ∈ R). Similarly, we also give necessary and sufficient conditions for QB ∞-rings in the second part of the paper.Отримано деякi спiввiдношення для квазiодиничних регулярних кiлець та QB-кiлець, а також для псевдоодиничних регулярних кiлець та QB∞-кiлець. У першiй частинi статтi доведено, що (кiльце R з властивiстю замiни є QB-кiльцем) ⇔ (якщо x∈R є регулярним, то iснує квазiодиничний регулярний елемент w∈R такий, що x=xyx=xyw для деякого y∈R) ⇔ (якщо aR+bR=dR in R в R, то iснує квазiодиничний регулярний елемент w∈R такий, що a+bz=dw для деякого z∈R). Аналогiчним чином отриманi необхiднi та достатнi умови для QB∞-кiлець наведено у другiй частинi статтi

    Fatty acid 2-hydroxylation inhibits tumor growth and increases sensitivity to cisplatin in gastric cancer

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    Background: Most gastric cancers are diagnosed at an advanced or metastatic stage with poor prognosis and survival rate. Fatty acid 2-hydroxylase (FA2H) with high expression in stomach generates chiral (R)-2-hydroxy FAs ((R)-2-OHFAs) and regulates glucose utilization which is important for cell proliferation and invasiveness. We hypothesized that FA2H impacts gastric tumor growth and could represent a novel target to improve gastric cancer therapy. Methods: FA2H level in 117 human gastric tumors and its association with tumor growth, metastasis and overall survival were examined. Its roles and potential mechanisms in regulating tumor growth were studied by genetic and pharmacological manipulation of gastric cancer cells in vitro and in vivo. Findings: FA2H level was lower in gastric tumor tissues as compared to surrounding tissues and associated with clinicopathologic status of patients, which were confirmed by analyses of multiple published datasets. FA2H depletion decreased tumor chemosensitivity, partially due to inhibition of AMPK and activation of the mTOR/S6K1/Gli1 pathway. Conversely, FA2H overexpression or treatment with (R)-2-OHFAs had the opposite effects. In line with these in vitro observations, FA2H knockdown promoted tumor growth with increased level of tumor Gli1 in vivo. Moreover, (R)-2-OHFA treatment significantly decreased Gli1 level in gastric tumors and enhanced tumor chemosensitivity to cisplatin, while alleviating the chemotherapy-induced weight loss in mice. Interpretation: Our results demonstrate that FA2H plays an important role in regulating Hh signaling and gastric tumor growth and suggest that (R)-2-OHFAs could be effective as nontoxic wide-spectrum drugs to promote chemosensitivity. Fund: Grants of NSF, NIH, and PAPD. Keywords: Fatty acid 2-hydroxylation, Gastric cancer, Lipid metabolism, mTOR, Chemotherapy, Hedgehog pathwa

    Research and experiment of electrostatic spraying system for agricultural plant protection unmanned vehicle

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    IntroductionThe traditional spraying system is not suitable for agricultural plant protection in small plots due to its disadvantages of weak droplet refining ability, small spraying area, large pesticide consumption, and high manual spraying cost. At present, spraying pesticide is the main way to resist crop diseases and insect pests. The utilization rate of pesticide is only 38.8% in China, which leads to serious waste and serious environmental pollution. It is necessary to develop advanced plant protection equipment and pesticide application technology to solve the problem. The combination of agricultural plant protection vehicle and electrostatic spray technology may solve the problems of spraying efficiency, droplet adsorption rate and evenness. It is of great significance to improve the efficiency of plant protection and pesticide utilization.MethodsIn this paper, the principle of droplet charging is described, an electrostatic spraying system is designed and tested, and the effects of charging voltage and pump pressure on the droplet charge ratio and droplet size are analyzed.Results and discussionThis study has shown that electrostatic spraying systems are suitable for agricultural plant protection unmanned vehicles

    Stomatal Conductance and Morphology of Arbuscular Mycorrhizal Wheat Plants Response to Elevated CO2 and NaCl Stress

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    Stomata play a critical role in the regulation of gas exchange between the interior of the leaf and the exterior environment and are affected by environmental and endogenous stimuli. This study aimed to evaluate the effect of the arbuscular mycorrhizal (AM) fungus, Rhizophagus irregularis, on the stomatal behavior of wheat (Triticum aestivum L.) plants under combination with elevated CO2 and NaCl stress. Wheat seedlings were exposed to ambient (400 ppm) or elevated (700 ppm) CO2 concentrations and 0, 1, and 2 g kg−1 dry soil NaCl treatments for 10 weeks. AM symbiosis increased the leaf area and stomatal density (SD) of the abaxial surface. Stomatal size and the aperture of adaxial and abaxial leaf surfaces were higher in the AM than non-AM plants under elevated CO2 and salinity stress. AM plants showed higher stomatal conductance (gs) and maximum rate of gs to water vapor (gsmax) compared with non-AM plants. Moreover, leaf water potential (Ψ) was increased and carbon isotope discrimination (Δ13C) was decreased by AM colonization, and both were significantly associated with stomatal conductance. The results suggest that AM symbiosis alters stomatal morphology by changing SD and the size of the guard cells and stomatal pores, thereby improving the stomatal conductance and water relations of wheat leaves under combined elevated CO2 and salinity stress
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