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151.
152.
通过对覆膜全过程的分析和优化实验,确定影响覆膜砂性能的工艺因素主要有:原砂的加热温度、加入树脂后的混砂时间、加入固化剂的混砂时间等,为了获得最佳的工艺参数,对各个工艺参数进行了正交实验。实验结果表明:为获得较高的热态抗拉强度,可以选用砂温180℃,加树脂后的混砂时间为100S,加固化剂后的混制时间为40S,加硬脂酸钙后的混制时间为30S;为获得较好的常温抗拉强度,可以选用砂温180℃,加树脂后的混砂时间为80s,加固化剂后的混制时间为30s,加硬脂酸钙后的混制时间为20s。 相似文献
153.
讨论了用冲天炉熔炼高铬铸铁的可能性。分析在明,冲天炉条件下铬铁合金熔化的热力学条件是不合适的,它将导致大量铬元素的烧损,增加铁液夹杂物数量。其次,高铬铸铁的熔体,有强烈的从焦大中渗碳的趋势,故含碳量难以控制。认为用冲天炉熔炼高铬铸铁是不合适的。 相似文献
154.
研究了树脂砂型离心铸管表面质量及影响因素。结果表明,覆膜砂粒反和砂层厚反对铸件表面质量有显著影响。砂的粒度细时不易粘砂且铸件表面粗糙度高,而砂层厚度越薄表面质量越差,故至少需4mm厚的砂层。砂中加氧化铁粉时对防止粘砂不起作用,但砂层表面涂刷涂料时防止粘砂效果非常明显。 相似文献
155.
The efficient separation of water-in-oil emulsion is of significance in environment and energy filed, and it has become a world-wide challenge. Herein, we have presented a one-step, facile and low-cost approach to prepare superhydrophobic sands for efficient separation of water-in-oil emulsion. The as-prepared sand layers possessed a water contact angle higher than 151°, demonstrating their superior superhydrophobic property. Besides, the as-prepared sand layers could separate water-in-emulsions with separation efficiency up to 99.7%, which is superior to both traditional and superwettable filtration membranes. The effect of thickness of sand layer on separation performance was also investigated. The results showed that the filtration flux decreased with the increased of filtration thickness while the separation efficiency increased. The as-prepared sand layer proposed by this study is a processing candidate for separating water-in-oil emulsion in practical industry. Additionally,the as-prepared superhydrophobic sand fabrication method also provides an alternative for desert water storage. 相似文献
156.
以氧化铁皮作为除酸剂,与盐酸酸洗废液反应制得FeCl2溶液,再采用空气-双氧水双重氧化和沉淀法从中制得α-Fe2O3纳米颗粒。分析了FeCl2质量浓度、氨水质量浓度、超声时间和煅烧温度对产物的的粒径和纯度的影响。采用场发射扫描电子显微镜(SEM)和X射线衍射仪(XRD)对产物的形貌和结构进行了表征。优化实验结果表明,FeCl2质量浓度为16 g/L,氨水质量浓度为7.5 g/L,超声时间为50 min,煅烧温度为750℃时,制得了分散性虽然一般,但纯度较高的α-Fe2O3,其含量高达95.3%,平均晶粒尺寸约为38.2 nm。这为盐酸酸洗废液的资源化利用提供了实验基础。 相似文献
157.
Kvin Nay William J. Smiles Jacqueline Kaiser Luke M. McAloon Kim Loh Sandra Galic Jonathan S. Oakhill Andrew L. Gundlach John W. Scott 《International journal of molecular sciences》2021,22(8)
As life expectancy has increased, particularly in developed countries, due to medical advances and increased prosperity, age-related neurological diseases and mental health disorders have become more prevalent health issues, reducing the well-being and quality of life of sufferers and their families. In recent decades, due to reduced work-related levels of physical activity, and key research insights, prescribing adequate exercise has become an innovative strategy to prevent or delay the onset of these pathologies and has been demonstrated to have therapeutic benefits when used as a sole or combination treatment. Recent evidence suggests that the beneficial effects of exercise on the brain are related to several underlying mechanisms related to muscle–brain, liver–brain and gut–brain crosstalk. Therefore, this review aims to summarize the most relevant current knowledge of the impact of exercise on mood disorders and neurodegenerative diseases, and to highlight the established and potential underlying mechanisms involved in exercise–brain communication and their benefits for physiology and brain function. 相似文献
158.
159.
María Jos García Carlos Lucena Francisco Javier Romera 《International journal of molecular sciences》2021,22(9)
Iron (Fe) and phosphorus (P) are two essential elements for plant growth. Both elements are abundant in soils but with poor availability for plants, which favor their acquisition by developing morphological and physiological responses in their roots. Although the regulation of the genes related to these responses is not totally known, ethylene (ET) and nitric oxide (NO) have been involved in the activation of both Fe-related and P-related genes. The common involvement of ET and NO suggests that they must act in conjunction with other specific signals, more closely related to each deficiency. Among the specific signals involved in the regulation of Fe- or P-related genes have been proposed Fe-peptides (or Fe ion itself) and microRNAs, like miR399 (P), moving through the phloem. These Fe- or P-related phloem signals could interact with ET/NO and confer specificity to the responses to each deficiency, avoiding the induction of the specific responses when ET/NO increase due to other nutrient deficiencies or stresses. Besides the specificity conferred by these signals, ET itself could confer specificity to the responses to Fe- or P-deficiency by acting through different signaling pathways in each case. Given the above considerations, there are preliminary results suggesting that ET could regulate different nutrient responses by acting both in conjunction with other signals and through different signaling pathways. Because of the close relationship among these two elements, a better knowledge of the physiological and molecular basis of their interaction is necessary to improve their nutrition and to avoid the problems associated with their misuse. As examples of this interaction, it is known that Fe chlorosis can be induced, under certain circumstances, by a P over- fertilization. On the other hand, Fe oxides can have a role in the immobilization of P in soils. Qualitative and quantitative assessment of the dynamic of known Fe- and P-related genes expression, selected ad hoc and involved in each of these deficiencies, would allow us to get a profound knowledge of the processes that regulate the responses to both deficiencies. The better knowledge of the regulation by ET of the responses to these deficiencies is necessary to properly understand the interactions between Fe and P. This will allow the obtention of more efficient varieties in the absorption of P and Fe, and the use of more rational management techniques for P and Fe fertilization. This will contribute to minimize the environmental impacts caused by the use of P and Fe fertilizers (Fe chelates) in agriculture and to adjust the costs for farmers, due to the high prices and/or scarcity of Fe and P fertilizers. This review aims to summarize the latest advances in the knowledge about Fe and P deficiency responses, analyzing the similarities and differences among them and considering the interactions among their main regulators, including some hormones (ethylene) and signaling substances (NO and GSNO) as well as other P- and Fe-related signals. 相似文献
160.
Anne-Cathrine S. Vogt Tasneem Arsiwala Mona Mohsen Monique Vogel Vania Manolova Martin F. Bachmann 《International journal of molecular sciences》2021,22(9)
Iron is a critical metal for several vital biological processes. Most of the body’s iron is bound to hemoglobin in erythrocytes. Iron from senescent red blood cells is recycled by macrophages in the spleen, liver and bone marrow. Dietary iron is taken up by the divalent metal transporter 1 (DMT1) in enterocytes and transported to portal blood via ferroportin (FPN), where it is bound to transferrin and taken up by hepatocytes, macrophages and bone marrow cells via transferrin receptor 1 (TfR1). While most of the physiologically active iron is bound hemoglobin, the major storage of most iron occurs in the liver in a ferritin-bound fashion. In response to an increased iron load, hepatocytes secrete the peptide hormone hepcidin, which binds to and induces internalization and degradation of the iron transporter FPN, thus controlling the amount of iron released from the cells into the blood. This review summarizes the key mechanisms and players involved in cellular and systemic iron regulation. 相似文献