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排序方式: 共有388条查询结果,搜索用时 156 毫秒
41.
为了考察煤灰中的化学组分对熔融特性温度的贡献,借助我国69种重要的商业用煤的灰熔融特性温度和灰中SiO2和Al2O3等6种主要化学组分的测试数据,利用多项式模型的偏回归函数分析方法,对煤灰的熔融特性温度进行一至四阶多项式模型回归分析,获得了各化学组分的偏回归函数。研究结果表明:各化学组分的偏回归函数能够表现熔融温度对应于该组分变化的趋势;同一组分偏回归函数不同,该组分对变形温度、软化温度和熔融温度的影响存在较大的差异;CaO和TiO2的偏回归函数反映熔融温度变化趋势的可信度最高。实验为进一步研究煤灰熔融特性温度的数学模型和参数选择提供参考。 相似文献
42.
Fly ash (FA) from coal in Orissa (India) was used for amending soil at levels equivalent to 0, 1, 2.5, 5, 10 and 15 metric
tons per ha in which, rice was grown and elemental residues of amended soil and plant parts were enumerated. FA amendments
caused significant improvement in soil quality and germination percentage of rice seeds. Growth (shoot length, leaf area and
pigment composition) and yield (panicle length, seeds per panicle, seed weight and yield per plant) of rice increased with
an increase in FA amendments. Catalase and peroxidase activities of young leaves increased initially in plants cultivated
at lower FA levels but declined sharply at higher FA levels while the protein content of seeds improved at higher FA levels.
Sodium content of rice-roots did not change with FA amendments but the contents of K, P, Mn, Ni, Co, Pb, Zn, Cu, Cr, and Cd
showed a progressive increase. Seeds of plants grown in FA amended soils accumulated Cu, Pb, Cr and Cd in amounts below allowable
limits. Based on the data obtained we found that flooded-rice soil amended at 10 metric tons FA per ha level of FA not only
improved the physical properties of the soil but also contributed to better growth and yield of rice. 相似文献
43.
目的:对《中国药典))2005年版一部中蒲黄薄层鉴别和检查项进行修订。方法:以香蒲新苷和异鼠李素-3-O-新橙皮苷作对照,采用聚酰胺薄膜,以丙酮-水(1:2)为展开剂进行鉴别;杂质检查时将筛分法与显微镜检相结合;采用2005年版药典附录Ⅸ K方法,测定了总灰分与酸不溶性灰分。结果:采用改进后的薄层鉴别方法对蒲黄中的香蒲新苷和异鼠李素-3-O-新橙皮苷进行鉴别,灵敏度高,斑点清晰,分离度好。采用筛分法进行杂质检查时,用7号药筛,称样量为10.0g,筛分时间为2min;增订的总灰分限度为10.0%,酸不溶性灰分的限度为4.0%。结论:改进后的薄层鉴别方法简便,快速,灵敏;修订后的检查项较为合理,更有利于蒲黄的质量控制。 相似文献
44.
45.
Effects of ozone and fine particulate matter (PM2.5) on rat system inflammation and cardiac function
In order to understand the toxic mechanisms of cardiovascular system injuries induced by ambient PM2.5 and/or ozone, a subacute toxicological animal experiment was designed with exposure twice a week for 3 continuous weeks. Wistar rats were randomly categorized into 8 groups (n = 6): 1 control group, 3 groups exposed to fine particulate matters (PM2.5) alone at 3 doses (0.2, 0.8, or 3.2 mg/rat), 1 group to ozone (0.81 ppm) alone and 3 groups to ozone plus PM2.5 at 3 doses (0.2, 0.8, or 3.2 mg/rat). Heart rate (HR) and electrocardiogram (ECG) was monitored at approximately 24-h both after the 3rd exposure and the last (6th) exposure, and systolic blood pressure (SBP) was monitored at approximately 24-h after the 6th exposure. Biomarkers of systemic inflammation and injuries (CRP, IL-6, LDH, CK), heart oxidative stress (MDA, SOD) and endothelial function (ET-1, VEGF) were analyzed after the 6th exposure. Additionally, myocardial ultrastructural alterations were observed under transmission electron microscopy (TEM) for histopathological analyses. Results showed that PM2.5 alone exposure could trigger the significant increase of CRP, MDA, CK, ET-1 and SBP and decrease of heart rate variability (HRV), a marker of cardiac autonomic nervous system (ANS) function. Ozone alone exposure in rats did not show significant alterations in any indicators. Ozone plus PM2.5 exposure, however, induced CRP, IL-6, CK, LDH and MDA increase, SOD and HRV decrease significantly in a dose–response way. Meanwhile, abnormal ECG types were monitored in rats exposed to PM2.5 with and without ozone and obvious myocardial ultrastructural changes were observed by TEM. In conclusion, PM2.5 alone exposure could cause inflammation, endothelial function and ANS injuries, and ozone potentiated these effects induced by PM2.5. 相似文献
46.
Nowadays, using fly ash for zeolites production has become a well-known strategy aimed on sustainable development. During zeolite synthesis in a hydrothermal conversion large amount of post-reaction solution is generated. In this work, the solution was used as a substrate for Na-A and Na-X zeolites synthesis at laboratory and technical scale. Obtained materials were characterized using particle size analysis, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), and nitrogen adsorption/desorption isotherm. Produced zeolites revealed high purity (>98%) and monomineral zeolitic phase composition. The SiO2 content was in the range 39–42% and 40–38%, whereas Al2O3 content was 23–22% and 25–26% for Na-X and Na-A, respectively. TEM and BET analyses revealed Na-X zeolite pores were almost identical to commercial 13X with SBET in the range 671–734 m2/g. FTIR indicated slight differences between materials obtained at laboratory and technical scale in Si-O-(Si/Al) bridges of the zeolitic skeleton. The results showed good replicability of the laboratory process in the larger scale. The proposed method allows for waste solution reusability with a view to highly pure zeolites production in line with circular economy assumptions. 相似文献
47.
The aim of the study was to generate rules for the prediction of the chloride resistance of concrete modified with high calcium fly ash using machine learning methods. The rapid chloride permeability test, according to the Nordtest Method Build 492, was used for determining the chloride ions’ penetration in concrete containing high calcium fly ash (HCFA) for partial replacement of Portland cement. The results of the performed tests were used as the training set to generate rules describing the relation between material composition and the chloride resistance. Multiple methods for rule generation were applied and compared. The rules generated by algorithm J48 from the Weka workbench provided the means for adequate classification of plain concretes and concretes modified with high calcium fly ash as materials of good, acceptable or unacceptable resistance to chloride penetration. 相似文献
48.
This study investigated the use of coal bottom ash (bottom ash) and CaO-CaCl2-activated ground granulated blast furnace slag (GGBFS) binder in the manufacturing of artificial fine aggregates using cold-bonded pelletization. Mixture samples were prepared with varying added contents of bottom ash of varying added contents of bottom ash relative to the weight of the cementless binder (= GGBFS + quicklime (CaO) + calcium chloride (CaCl2)). In the system, the added bottom ash was not simply an inert filler but was dissolved at an early stage. As the ionic concentrations of Ca and Si increased due to dissolved bottom ash, calcium silicate hydrate (C-S-H) formed both earlier and at higher levels, which increased the strength of the earlier stages. However, the added bottom ash did not affect the total quantities of main reaction products, C-S-H and hydrocalumite, in later phases (e.g., 28 days), but simply accelerated the binder reaction until it had occurred for 14 days. After considering both the mechanical strength and the pelletizing formability of all the mixtures, the proportion with 40 relative weight of bottom ash was selected for the manufacturing of pilot samples of aggregates. The produced fine aggregates had a water absorption rate of 9.83% and demonstrated a much smaller amount of heavy metal leaching than the raw bottom ash. 相似文献
49.
50.
G Mazzanti L Battinelli C Daniele S Costantini L Ciaralli M G Evandri 《Food and chemical toxicology》2008,46(9):3043-3047
The widespread use of herbal drugs, among which those coming from eastern Countries, has created a more compelling need for quality, a pre-requisite that can influence safety. In the present study, 10 Chinese crude herbal drugs marketed in Italy (Radix Ginseng, Radix Astragali, Rhizoma Coptidis, Rhizoma Atractylodis Macrocephalae, Radix Bupleuri, Radix Rehmanniae, Radix Paeoniae Alba, Pericarpium Citri Reticulatae, Radix Polygalae, Radix Salviae Miltiorrhizae) were analysed by the following purity assays: foreign matter, total ash, microbial and heavy metal contamination. Each herbal drug was purchased in Italy from three different sources: two Chinese firms and one Chinese herbal shop. Except for the heavy metal content, the tests were performed according to the European Pharmacopoeia. The presence of parasites was shown in two samples; moreover, level of ash (in three samples), lead content (in one sample) and total viable aerobic count (in one sample), were higher than the limits set by the European or Italian Pharmacopoeias. Our results, even if obtained from a small number of herbal drugs, show some purity issues and underline the importance of the quality control, particularly for this kind of products whose therapeutic value is not always demonstrated. 相似文献