水源切换期用户水质跟踪监测及铁稳定性分析

针对北方某市水源切换对典型地区实际给水管网铁稳定性的影响开展试验研究。选取2个小区用户各1家,对其管网出水水质进行连续10个月的跟踪监测。结果表明,在本次水源切换过程中,管网水的SO42-有较大幅度变化,平均从25 mg/L增加到75 mg/L,之后又降至45 mg/L;造成管网出水的浊度和总铁有所增加,部分监测值超出饮用水标准,最高达到6 NTU和1.2 mg/L。不同小区管道铁稳定性存在明显差异,管网水中铁含量和浊度具有一定的线性关系。分析水源切换前后不同时期管网出水水质的变化,得出SO42-与管垢铁释放有较好的相关性。

给水管网中铁稳定性问题综合控制技术研究

总结了管网系统管理、管道维护与改造、水质调节技术三项基本的管网铁稳定性控制对策,并在此基础上提出了适合我国实际情况,针对不同管网和不同水质状况的5种给水管网铁稳定性综合控制方案,并对各方案进行了经济技术比较分析。

淡化海水进入市政供水管网的铁稳定性

该文针对常规地表水源切换为淡化海水对既有供水管网水质铁稳定性的影响开展研究。选取中国市政管网系统中常用的灰口铸铁管和球墨铸铁管,利用实验室制作的管段模拟反应器,分析不同氯离子质量浓度的淡化海水对两种管材管段铁释放的影响。结果表明:供水管网铁释放量与淡化海水中氯离子质量浓度具有显著相关性,氯离子质量浓度从50mg/L增加至240mg/L,8h滞留水的总铁释放量最大增加灰口铸铁管约8.00mg/L,球墨铸铁管约0.40mg/L。供水管网内部腐蚀产物特性与管材密切相关,因而不同管材应对水质变化的耐受性有明显差异。淡化海水由于其水质不稳定,具有强侵蚀性,进入灰口铸铁管的供水管网前,需与常规水源水勾兑使用,严格控制淡化海水的氯离子质量浓度,以免引发严重的管网"黄水"问题。

高锰酸盐预氧化去除太湖原水中稳定性铁、锰

太湖B支流河水属于低浊、高藻、高铁锰、高色度和高耗氧量水质,其中铁、锰主要以溶解态和胶体态(铁、锰化合物胶体)存在。胶体态铁、锰被有机物膜包裹,和溶解态铁、锰形成了高稳定性铁、锰,采用常规给水工艺处理时难于去除。为此,开展了高锰酸盐(PPC)预氧化去除该原水中稳定性铁、锰的研究。结果表明,高锰酸盐对稳定性铁、锰的去除效果好,但受预氧化时间、pH值、水中本底成分的影响较大。在预氧化时间为30 m in、原水锰含量<0.67 mg/L时,对锰的去除率接近100%;在预氧化时间为60 m in、原水铁含量<0.5 mg/L时,对铁的去除率约为100%。当原水为酸性和碱性时,预氧化对铁、锰的去除率较高,在中性条件下去除率则相对较低。

稳定性同位素示踪测定NaFeEDTA强化酱油中铁在人体中吸收率

采用铁稳定性同位素54Fe和58Fe分别标记FeSO4及NaFeEDTA并以稀土元素 (Dy)作为排泄物回收标记物。自愿受试人群为 18～ 2 2岁健康女性。采用我国典型城镇成年女性膳食模式。两种铁剂及Dy以酱油为食物载体一同分 2日 6次经口给入。实验其间每日留取受试人膳食样品并完全收集受试人在实验期的排泄物。采用原子吸收和ICP -MS分别检测膳食及排泄物中总铁含量和铁同位素比例 ,对两种铁剂中的铁的吸收率进行比较。结果表明 ,FeSO4中铁在人体中的平均吸收率为 4 73% ,NaFeEDTA为 10 5 1%。二者差异为极显著(P <0 0 1)。说明NaFeEDTA中铁的吸收率优于FeSO4。

高锰酸盐预氧化强化去除藕池河原水中稳定性铁锰

采用高锰酸盐(PPC)预氧化处理强化去除洞庭湖藕池河地表水中稳定性铁锰.试验结果表明,高锰酸盐对藕池河地表水中稳定性铁锰去除效果好,但去除效果受到预氧化时间、pH值、水中本底物质浓度影响.预氧化时间30 min时,在原水锰含量低于0.71 mg/L时,对锰的去除率可接近100%;预氧化时间为60min时,在原水铁含量低于0.62 mg/L时,对铁的去除率可接近100%.当原水为酸性和碱性环境条件时,预氧化对铁锰的去除率较高,在中性条件下去除率则相对较低.

乙二胺四乙酸铁钠中铁在人体吸收率的研究

目的 : 研究在中国典型膳食条件下乙二胺四乙酸铁钠 ( Na Fe EDTA)中铁在人体的吸收率。方法 : 采用铁稳定性同位素54 Fe和58Fe分别标记 Fe SO4 和 Na Fe EDTA并以稀土元素镝 ( Dy)作为排泄物回收标记物。自愿受试者为 1 8～ 2 2岁健康女性。采用我国典型城镇成年女性膳食模式。两种铁剂和 Dy以酱油为食物载体一同分两天 6次经口给入。实验期间每日留取受试者膳食样品并收集受试者在实验期的粪便。采用原子吸收 ( AAS)和等离子体质谱 ( ICP- MS)分别检测膳食和粪便中总铁含量和铁同位素比例 ,对两种铁剂中铁的吸收率进行比较。结果 : Fe SO4 的铁平均吸收率为 4.73% ,而 Na Fe EDTA为 1 0 .51 % ,两者差异为极显著 ( P<0 .0 1 )。结论 : Na Fe EDTA中铁的吸收率优于 Fe SO4 。

改性滤料强化过滤微污染地表水研究

针对太湖流域某地水厂常规过滤介质对微污染水源水中典型污染物去除效果不甚理想的情况,开展了碱式聚合氯化铝(PAC)改性滤料强化过滤试验研究.研究结果表明:PAC改性石英砂滤料对浊度、CODMn、UV254的去除效果明显优于未经改性的普通石英砂滤料,去除率分别提高了0.3%、12.4%、13.8%;同时,能强化对稳定性铁锰的过滤效果,在进水铁浓度为1.21 mg/L时,改性滤料对铁的去除率比普通石英砂滤料高9.1%.

Alloying behavior and characterization of(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy materials fabricated by mechanical alloying

The alloying behavior and microstructures of the(CoCrFeNiMn)_(90)M_(10)(M=Al,Hf)high-entropy alloy(HEA)powders fabricated by mechanical alloying were studied.The CoCrFeNiMn)_(90)Al_(10) powders have duplex solid-solution structures.In contrast,nanocrystalline HfNi_(3) anchoring in amorphous structures is found in the(CoCrFeNiMn)_(90)Hf_(10) powders.The(CoCrFeNiMn)_(90)Al_(10) powders show better ferromagnetic behaviors,mainly explained by the facilitated motion of the magnetic domain induced by the coherent interface between duplex phases.Combined with our previous work,the rules of forming solid-solution and amorphous phase in as-milled HEA powders are preliminarily proposed.It is found that,compared with the as-cast HEA reported previously,the variation range of mixing enthalpy with atomic size difference of the solid-solution formed in as-milled HEA powders is broader.Moreover,the variation ranges between mixing enthalpy and entropy with atomic size difference of the amorphous phase in HEA powder become wider than those of high-entropy bulk metallic glass.

Comprehensive analysis of slope stability and determination of stable slopes in the Chador-Malu iron ore mine using numerical and limit equilibrium methods

One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador- Malu iron ore mine, one of the most important iron ore mines in central Iran, it was considered vital to perform a comprehensive slope stability analysis. At first, we divided the existing rock hosting pit into six zones and a geotechnical map was prepared. Then, the value of MRMR （Mining Rock Mass Rating） was determined for each zone. Owing to the fact that the Chador-Malu iron ore mine is located in a highly tectonic area and the rock mass completely crushed, the Hoek-Brown failure criterion was found suitable to estimate geo-mechanical parameters. After that, the value of cohesion （c） and friction angle （tp） were calculated for different geotechnical zones and relative graphs and equations were derived as a function of slope height. The stability analyses using numerical and limit equilibrium methods showed that some instability problems might occur by increasing the slope height. Therefore, stable slopes for each geotechnical zone and prepared sections were calculated and presented as a function of slope height.

Effect of phase transition on room temperature ferromagnetism in cerium doped ZnS nanorods

The effects of Ce doping on the structure,optical,oxidation,thermal and magnetic properties of ZnS:Ce nanorods synthesized by a chemical co-precipitation method were reported.The crystalline phase transformation from cubic to hexagonal structure was observed upon doping ZnS with Ce.Magnetic measurements showed the existence of room temperature ferromagnetism in Ce-doped ZnS nanorods.X-ray photoelectron spectroscopic(XPS)measurements provided evidence for Zn-S bonds and oxidation state of Ce in the near-surface region.Raman spectrum provided evidence for the presence of defects as well as hexagonal structure of 5 wt.%Ce doped ZnS nanorods.Ce substitution induced shape evolution was studied by using TEM.DRS spectra further validated the incorporation of Ce^3+ions.The present study reveals that Ce doped ZnS nanorods may find applications in spintronic devices.

Stabilization of Magnetite Nanoparticles by Encapsulation into the Silica Matrix

Different methods have been investigated for the synthesis of magnetic nanoparticles. Control of the particle size, dispersion, purity and stability have been always regarded an issue. In this study magnetite （Fe304） superparamagnetic nanoparticles with a size range about 20 nm have been successfully synthesized using chemical co-precipitation method from the solution of ferrous/ferric mixed salt-solution in alkaline media in oxygen-free environment. The sol-gel method has been chose to encapsulate magnetic nanoparticles into silica matrix. The phase structures, morphologies, surface area, functional classes and magnetic properties have been characterized by X-ray diffraction, SEM and AFM, BET, FT-IR and VSM. The results showed that the resultant films, consisting of encapsulated magnetite have crack free and smooth surface with a roughness value 1.5 rim.

Rapid Regeneration of Chelated Iron Desulfurization Solution Using Electrochemical Reactor with Rotating Cylindrical Electrodes

A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as the rotation speed of electrode,voltage,and inlet air and liquid flow rates,on the regeneration rate was investigated.Compared with the traditional tank-type reactor,the regeneration rate with the new electrochemical reactor was increased significantly.Under the optimum conditions,the regeneration rate was increased from 45.3%to 84.8%.Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency,smaller equipment size and good stability in operation.

Stability assessment and feature analysis of slope in Nanfen Open Pit Iron Mine

Under the combined influences of special topography and the long term mining in Nanfen Open Pit Iron Mine, many large scale landslide masses appeared in heading side of stope, and tens of millions of iron mine is buried underside, making great economic losses. In order to guide the safety mining and increase the supply quantity, this paper through the use of MSARMA-method and the ''MSARMA evaluation and analytical system for slope stability analysis'' based on this method, which aimed at the quantitative evaluating of the slope stability before and after the actual mining below the slip mass, and the sensitivity analysis for the main influencing factor, providing scientific proof for the parameter optimization of open mine surface slope, the security and sustainable exploitation.

Stability analysis and treatment of No.2 dump of Nanfen iron mine

On the basis of the study on the engineering geological characteristics of No.2 dump of Nanfen iron mine and the analysis of the failure mode of dump landslide,the stability of the present dump,the stability of the dump 20 years later and the stability of double-bench dump are analyzed.Then,the debris flow risk is evaluated by fuzzy mathematics method.Finally,the comprehensive treatment for the dump is suggested.It is concluded that ① In rainy and snowmelt period,the stability would be decreasing sharply when ground water is not drained out in time;② Double-bench dumping mode will improve stability of the dump little;③ Debris flow risk is middle danger.The interim debris flow with medium scale may occur.④ Monitoring,draining and baffling work ought to be well done.⑤ In order to prevent the damage of landslide and debris flow,three measures are adopted,including setting rockfall net,setting the debris flow barrier and removing the residents.

Parametric Analysis of the Stability of Degraded Railroad Platforms

The current study is developed based on one of the types of subgrade rupture risk suggested by Selig and Waters （1994）. It aims to evaluate subgrade stability railroad, which consists of the slope stability analysis of a railway yard embankment subjected to a wagon load type gondola parked on this track. This proposed analysis was taken into consideration because there are Brazilian railroads in high deterioration level. In some of these lines the tracks are submitted to increasing amount of load every year. The adopted model slope stability to the studied railroad embankments considers the rupture on circular line. It was applied the Geoslope-Slope/W software, version 6, to the evaluation of the platform-slope system. Several situations are adopted to reach the minimum safety slope, permitting to analyze the platform stability to keep railroad traffic under adequate safety level.

Controllable Optical Bistability in a Crystal of Molecular Magnets System

We investigate the formation of optical bistability （OB） in a crystal of molecular magnets contained in a unidirectional ring cavity. The crystal is subjected to one dc magnetic field and two （probe and coupling） ac resonant magnetic field. The results show that OB can be controlled efficiently by adjusting the intensity of the control field, the detuning of probe magnetic field and the cooperation parameter, Furthermore, within certain parameter range, the optical multistablity （OM） can also be observed in the crystal medimn. This＇ investigation can be used for designing new types of nonelectronic devices for realizing switching process.

Effect of Storage Temperature on Sensory and Physicochemical Properties of Wheat Flour Fortified with Elevated Levels of Vitamin A in Combination with Three Types of Iron

Many persons worldwide are deficient in micronutrients, two of the most common being vitamin A and iron. Fortification of staple food is a commonly used and effective method of boosting micronutrient intake. Wheat flour is widely used around the world and makes a good vehicle for fortification, but there is a lack of studies on the storage stability of fortified wheat flour. In this study, we fortified wheat flour with elevated levels of vitamin A and three sources of iron and stored it for up to 16 weeks at refrigerated or room temperature or elevated temperature. The rate of disappearance of vitamin A was monitored by high pressure liquid chromatography, and the rate of disappearance was fotmd to be directly proportional to the duration of storage and storage temperature. Higher temperatures contributed to greater loss of vitamin A. Iron, regardless of source, did not play a major role in contributing to the rate of vitamin A loss. Flour functionality was assessed by baking loaves of bread from the stored flour and assessing physical properties as well as subjecting the loaves to an expert sensory panel. Functionality also changed with time and temperature of storage, but sensory analysis found that these changes were not detrimental to the quality of bread baked from the stored flours. Trained sensory panelists found that breads baked from flours fortified with ferrous sulfate and stored at the three temperatures for times up to eight weeks were markedly different from fortified flours using hydrogen reduced irons.

Investigation of the spike-stall warning method using the blade passing signal

The vaned-diffuser usually brings compressor instability problems under the small flow rate, for instance the spike-type rotating stall phenomenon which restricts the operation range and may cause the trouble of blade fatigue. Since it is difficult to mathematically predict the spike-type stall for its randomness, finding out a practical method to warning this stall precursor appears to be meaningful. The paper explains the relationship between the spike-type precursor and the blade passing irregularity coefficient to analyze whether this coefficient is appropriate for the spike-stall warning inside a centrifugal compressor with the vaned-diffuser. The advanced wireless measurements were conducted on a 1.5 stages test centrifugal compressor to capture the unsteady behavior progressing from the design to stall inception within the region between the impeller trailing edge(TE) and diffuser leading edge(LE). The circumferential distribution of the blade passing irregularity has been quantitatively revealed.The steep increase of the blade passing irregularity at some "special locations", which is responsible for the onset of the spiketype precursor, is highlighted. Also, to further understand the spike precursor inside the diffuser passage corresponding to the circumferential "special location" with maximum irregularity, the high-response transient measurement within this passage is presented. With the help of full-annulus computational fluid dynamics(CFD) simulation and the mathematical model, it is proved that the blade passing irregularity precisely reflects the flow characteristics during the spike precursor, which presents the guidance for this stall warning method.

Soil Aggregate Stability and Iron and Aluminium Oxide Contents Under Different Fertiliser Treatments in a Long-Term Solar Greenhouse Experiment

Soil in greenhouses is likely to suffer a gradual decline in aggregate stability. Determination of the effects of different fertiliser practices on soil aggregate stability is important for taking advantage of solar greenhouses. Soil aggregate stability and iron （Fe） and aluminium （A1） oxide contents were investigated in a 26-year long-term fertilisation experiment in greenhouse in Shenyang, China, under eight fertiliser treatments： manure （M）, fertiliser N （FN）, fertiliser N with manure （MN）, fertiliser P （FP）, fertiliser P with manure （MP）, fertiliser NP （FNP）, fertiliser NP with manure （MNP）, and control without any fertiliser （CK）. A wet sieving method was used to determine aggregate size distribution and water-stable aggregates （WSA）, mean weight diameter and geometric mean diameter as the indices of soil aggregate stability. Different fertiliser treatments had a statistically significant influence on aggregate stability and Fe and A1 oxide contents. Long-term application of inorganic fertilisers had no obvious effects on the mass proportion of aggregates. By contrast, manure application significantly increased the mass proportion of macroaggregates at the expense of microaggregates. All treatments, with the exception of FNP, significantly increased the stability of macroaggregates but decreased that of microaggregates when compared with CK. Aggregation under MP and MN was better than that under M and MNP; however, no significant differences were found among inorganic fertiliser treatments （i.e., FN, FP, and FNP）. A positive relation was found between pyrophosphate-extractable Fe and WSA （r=0.269）, but no significant relations were observed between other Fe and Al oxides and aggregate stability.