钢铁粉尘与高氯飞灰协同脱除有害元素的试验

针对钢铁厂难处理粉尘有害元素含量高而制约其资源化利用的问题,以转炉泥为研究对象,通过卧式管炉模拟高温处理工艺生产条件,研究了转炉泥单独焙烧时有害元素的脱除特征,焙烧过程可脱除部分K、Na、Zn、Pb,但因氯低导致氯化挥发的脱除率低、焙烧温度高.针对此问题,将高氯垃圾飞灰配入转炉泥进行协同处置,以强化有害元素的脱除.研究...     

砷烟灰浸出液的制备及用于砷盐净化除钴试验研究

以某厂砷烟灰为原料,开展了砷烟灰浸出液的制备试验,然后以制备得到的砷烟灰浸出液作砷盐净化除钴的活化剂,开展了净化除钴条件、净化除钴综合条件及三氧化二砷作活化剂净化除钴对比和除钴优化条件等一系列试验研究。试验结果表明:采用砷烟灰制备砷烟灰浸出液及浸出液用于砷盐净化除钴工艺是切实可行的,不仅砷烟灰中的砷得到利用,同时,砷烟灰中铅、银、锑等有价金属与砷得以有效分离。     

含钴废料中提取钴的工艺研究

根据废钴片的特点,设计了提取方案,采用焙烧除杂、碱浸除Al—Li、酸浸出、溶液净化、草酸钴的制取作为主工艺流程。结果表明,硫酸浸出时钴的浸出率较低,可采用浸出率较高的盐酸浸出;经本工艺流程处理该类废钴片,最终可得到合格的草酸钴产品。摘要：根据废钴片的特点,设计了提取方案,采用焙烧除杂、碱浸除Al—Li、酸浸出、溶液净化、草酸钴的制取作为主工艺流程。结果表明,硫酸浸出时钴的浸出率较低,可采用浸出率较高的盐酸浸出;经本工艺流程处理该类废钴片,最终可得到合格的草酸钴产品。     

Kinetic studies on the removal of iron and aluminum from recombinant and site-directed mutant N-lobe half transferrins

Kinetic studies have been conducted in pH 7.4 Hepes buffer at 25 degreesC on the removal of Fe(III) and Al(III) from the recombinant N-lobe half molecule of human serum transferrin (Tf/2N) and from the R124A, K206A, and K296A mutants of this protein. The rates of iron removal from Tf/2N by 3-hydroxypyridin-4-one (deferiprone) and nitrilotriacetic acid (NTA) are essentially identical with previous results on N-terminal monoferric transferrin (Tf-FeN). For both Tf/2N and Tf-FeN, iron removal by deferiprone follows simple saturation kinetics, while iron removal by NTA follows simple first-order kinetics. There is some discrepancy between the two proteins with respect to iron removal by PPi, but this may be due to differences in the chloride concentrations among different studies. The addition of Fe(NTA)2 to R124A at ambient bicarbonate concentrations forms the Fe-NTA-Tf ternary complex, but the usual Fe-CO3-Tf complex can be formed by adding ferrous ion in the presence of a larger excess of bicarbonate. This complex releases its iron very rapidly by a mechanism that is first-order with respect to the ligand. This suggests that the first-order component of metal release from transferrin involves the displacement of the synergistic carbonate anion. Since iron removal from K206A and K296A at pH 7.4 is extremely slow, studies have been conducted on the more labile Al3+ complexes of Tf/2N, K206A, and K296A. The removal of Al3+ from Tf/2N by PPi follows the same complex kinetic order with respect to the ligand concentration that is observed for iron removal, while the removal of Al3+ from both K206A and K296A reverts to a simple saturation process. The addition of perchlorate retards the removal of Al3+ from both K206A and K296A, suggesting that these lysine residues are not associated with the allosteric effects of inorganic anions on the rates of metal removal.     

某金矿含砷铅碱性工业废水的处理试验研究

针对某金矿含砷铅碱性工业废水,研究了采用重金属捕集剂和聚铁联合除铅和砷。试验结果表明:用聚铁可去除废水中的砷,但聚铁用量较大,且对铅的去除没有作用;同时采用聚铁和重金属捕集剂TMT-18F,可有效去除砷和铅,且在相同除砷效果下,TMT-18F的加入可大大减少聚铁的用量,处理后的废水可达标排放。     

Cu2O处理黄金冶炼酸性废水中Cl-的试验研究

黄金冶炼企业产生的酸性废水一般采用石灰中和法处理后返回系统使用，但该方法的缺点是无法去除废水中的Cl^-。为消除Cl^-不断沉积带来的危害，针对冶炼酸性废水开展了试验研究。通常Cl^-的去除原理是利用其他阴离子替换Cl^-，或者将Cl^-与其他阳离子一并去除。利用Cu₂O作为沉淀剂，与Cl^-共同沉淀，以达到去除Cl^-的目的。为确定最佳试验条件，考察了在不同pH值、温度和Cu₂O用量情况下Cl^-的去除效果。试验结果表明：在室温条件下，当溶液pH值为0.5，Cu₂O用量为10 mg/L，反应时间为20 min时，可获得Cl^-去除率达95%以上的良好效果。结果证明，利用Cu₂O能够有效去除黄金冶炼酸性废水中的Cl^-，且生成的Cu₂O沉淀在酸性废水中稳定存在，易于过滤去除。在实际生产工艺中，Cu₂O也实现了循环除氯，节约了生产成本，为同类型企业去除酸性废水中Cl^-提供了参考。     

Modeling Mass Removal during In Situ Air Sparging

A model was developed to simulate mass removal during in situ air sparging. The model captures the physical characteristics of the air plume and employs conventional methods to simulate mass transfer. A parametric study was conducted using the model to assess how chemical properties, the operational method, and media affect mass removal during in situ air sparging. Mass removal is particularly sensitive to Henry's law constant, and the aqueous diffusion coefficient when Henry's law constant is high. Simulations of pulsed and continuous air injection show that pulsed injection can yield greater mass removal than continuous air injection for certain pulse cycles. Mass removal is generally greater at higher injection rates, but the increase in mass removal diminishes as the injection rate increases. Parametric analysis also showed that mass is removed faster when air channels are narrower or more tortuous (i.e., in coarser or more well-graded formations).     

Reexamination of sodium-liquid ammonia reduction in the peptide chemistry

Sodium-liquid ammonia reduction has been used for over 50 years for removal of benzyl-type protecting groups in peptide chemistry. Up until now a definitely blue end-point has generally been accepted for detection of the completion of reaction. Systematic investigation with model compounds has revealed that this is not only unnecessary for the complete removal of the protecting groups but also that the application of sodium in excess results in many undesired transformations which can simply be suppressed or even eliminated by optimizing the sodium consumption. Cleavage of tert.-butyloxycarbonyl group and N-C alpha bond, reduction of carboxamide groups to carbinol derivatives, transpeptidation and formation of a hydantoin derivative have been observed in model experiments by using sodium in excess.     

湿法炼锌过程中氟的脱除方法及应用

湿法炼锌过程中,硫酸锌溶液中氟含量的多少直接影响锌片的剥离,易导致工作条件恶化,不仅给整个湿法炼锌系统带来严重影响,也会造成较大的经济损失.多年来,氟的去除一直是冶炼企业面临的难题,特别是锌二次资源的利用,导致电解液中氟离子浓度已超出冶炼企业的控制要求.目前,针对高氟硫酸锌溶液尚无一种高效、经济的除氟方法.为此分析和总...     

Time-dependent changes in Dictyostelium discoideum adenylate cyclase activity upon incubation with ATP

In this study we report that preincubation of Dictyostelium discoideum membrane-bound adenylate cyclase with ATP over the concentration range 0.5 to 100 mM results in a loss of catalytic activity and that this effect persists even after removal of ATP. An analysis of the time course of this effect shows that, at 25 mM ATP, a 5- to 10-min preincubation results in 50% loss of activity. Additional studies on this effect showed that anhydride bond cleavage of ATP occurs during the preincubation. However, loss of catalytic activity is not porduced by ADP, AMP, cAMP, adenosine, pyrophosphate, or phosphate either separately or in pairs. Further, using the structural analogs adenosine 5'-(alpha, beta-methylene)triphosphate and adenyl-5'-yl imidodiphosphonate, we show that there is a direct correlation between alpha-beta-phosphoanhydride bond cleavage and the loss of catalytic activity. These results can be interpreted in terms of two classes of reaction mechanisms: either those involving covalent modifications or those involving a ligand-induced slow conversion of the adenylate cyclase from an active to an inactive form. Additional studies show that the addition of AMP to the reaction mixture, as well as removal of the membrane-bound 5'-nucleotidase activity, can prevent the loss of cyclase activity. These results suggest not only that adenylate cyclase activity is related to the AMP:ATP ratio but that the cyclase activity can be modified by the level of 5'-nucleotidase activity. Studies on the duration of the loss of activity produced by ATP show that following removal of ATP and additional incubation, a gradual recovery of cyclase activity is observed. This result suggests that under appropriate conditions the cyclase inactivation by ATP is reversible.     

粗四氯化钛脂肪酸除钒试剂的选择

开展不同类型脂肪酸精制四氯化钛试验研究,分析精TiCl_4样品和除钒尾渣。结果表明,饱和脂肪酸具有除钒效率较低、残渣分散性较好的特点,且碳链长度对除钒效率影响不大;不饱和脂肪酸除钒效率远高于相同链长的饱和脂肪酸,但是除钒泥浆黏度大、易结块;混合脂肪酸既可以保证除钒效率,也可以使残渣具有优良的分散性。     

Evaluation of Electric Arc Furnace Slag as a Potential Phosphate-Removal Substrate

A study was conducted to evaluate the performance of locally available electric arc furnace slag (EAFS) as a substrate for removing phosphorus from wastewater. First, in a laboratory study, EAFS was found to have high phosphorus removal efficiency for three P concentrations (0.3, 3.0, and 6.0 mg/L); this resulted in nearly 100% phosphorus removal in 24 h. Next, the experiment was repeated using aeration and similar phosphorus removal was observed but in a shorter contact time of 1 h. The adsorption capacity of EAFS was determined to be 1,458 mg/kg. In a pilot-scale study, over 90% P removal took place in the first 4 h under nonaerated conditions, and nearly 100% removal in 8 h. While the P removal with aeration was relatively less initially for the shorter residence times, a 100% removal was observed for the 24-h residence time.     

用针铁矿法从钴白合金酸浸液中除铁研究

研究了用针铁矿法从钴白合金酸浸液中除铁的过程.试验结果表明反应时间对除铁率影响不大,而终点pH和操作温度是除铁过程的主要影响因素.在终点pH=3.0,操作温度85℃,反应2h,除铁后浸液中含铁可降至0.01g/L,并且溶液中有价金属损失较少.     

For want of a nail: How absences cause events.

Causation by omission is instantiated when an effect occurs from an absence, as in The absence of nicotine causes withdrawal or Not watering the plant caused it to wilt. The phenomenon has been viewed as an insurmountable problem for process theories of causation, which specify causation in terms of conserved quantities, like force, but not for theories that specify causation in terms of statistical or counterfactual dependencies. A new account of causation challenges these assumptions. According to the force theory, absences are causal when the removal of a force leads to an effect. Evidence in support of this account was found in 3 experiments in which people classified animations of complex causal chains involving force removal, as well as chains involving virtual forces, that is, forces that were anticipated but never realized. In a 4th experiment, the force theory's ability to predict synonymy relationships between different types of causal expressions provided further evidence for this theory over dependency theories. The findings show not only how causation by omission can be grounded in the physical world but also why only certain absences, among the potentially infinite number of absences, are causal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

镍铁合金中杂质元素铜的去除

 镍铁合金是生产不锈钢的重要原料,其中的杂质元素必须严格控制,杂质元素铜质量分数过高会引起加工热脆性,通过加入脱铜剂FeS对镍铁合金中杂质元素铜的去除进行了系统研究。研究结果表明,脱铜率随着FeS加入量的增加而增大;镍铁合金中碳质量分数在增大至1%的过程中,脱铜率随着碳质量分数增加不断增大;镍铁合金初始铜质量分数越高,脱铜效果越好;在试验温度高于1 500 ℃的高温条件下,温度的升高对脱铜效果有影响但效果不显著。     

Etiology and indications for the management of impacted teeth

Impacted teeth are a medical deformity brought about by the dietary changes of modern civilization. Ample studies exist to show that the lack of a coarse, abrasive diet--an attritive diet--is the major cause of this problem in modern civilization. Our recent ancestors did not experience this problem or the problem of the underdeveloped lower jaw and resulting Class II malocclusion to the extent present in modern society. Medical and dental scientists, practitioners, and surgeons are aware of the devastation that impacted teeth can cause to the jaws and overall health of an individual and have issued numerous warnings to the profession and to the public regarding the several clear indications for the removal of impacted teeth. The issue has been clouded by the competing economic incentives present in our society, in which fee-for-service practitioners have been and are being replaced by practitioners with a disincentive to recommend surgical care for all but acutely infected or seriously symptomatic patients presenting with impacted teeth. Oral and maxillofacial surgeons practicing in the United States at this time are aware of the many clear indications for removal of impacted teeth and make every effort to communicate this information to their patients and other dental and medical practitioners. They are also aware of the contraindications to the removal of impacted teeth and advised patients appropriately when it is safe to retain and periodically observe by radiograph certain impacted teeth.     

Management of urocystoliths by voiding urohydropropulsion

Voiding urohydropropulsion is a nonsurgical method of removing uroliths from the urinary bladder. Any urocystolith of sufficient size to pass through the distended urethral lumen can be safely and effectively removed by this new technique. Compared to cystotomy, voiding urohydropropulsion offers several advantages: urolith removal can be performed in minutes, anesthetic period is shorter, postprocedural dysuria and hematuria are less severe, and it provides greater success for complete removal of small urocystoliths. This technique is not suitable for removal of large urocystoliths or uroliths that become lodged in the urethral lumen.     

Research Status of Numerical Simulation of Nonmetallic Inclusions Interfacial Removal

The removal of inclusions in liquid steel has always been the focus of research, and the removal of inclusions is mainly through the process of the inclusion through the slag–steel interface. The inclusion removal process can be subdivided into inclusions in molten steel grew up rise, in steel–slag interface through separation, adsorb dissolved in molten slag 3 steps. Based on the microscopic process of three steps, this article summarizes and discusses the mathematical model, fluid mechanics model, and experimental verification method of inclusion removal process, analyzes limiting and influencing factors of inclusion removal process, and comprehensively describes the numerical simulation research progress of inclusion removal process. With the development of numerical simulation techniques and experimental equipment, some progress has been made in the study of interfacial removal of inclusions. The inclusion interface removal behavior can be analyzed semiquantitatively based on dynamic force model. The computational fluid dynamics model has advantages in studying the phenomena of the inclusion interface, and the phase-field method is often used to simulate the removal process of the inclusion interface. The combination of water model and numerical simulation, high-temperature laser confocal method, and other methods is of great help to explore the interface behavior of inclusions.     

用针铁矿法从锌焙烧烟尘的热酸浸出液中除铁

研究了从锌焙烧烟尘常压热酸浸出液中沉淀针铁矿的过程。试验结果表明,反应时间和空气流量对除铁率的影响不显著,而反应温度和溶液终点pH是除铁过程的主要影响因素。在终点pH3.0、反应温度333 K、反应时间2 h、空气流量0.2 m3/min的条件下,除铁率超过99.5%,溶液中铁浓度可由40g/L降至0.1 g/L以下。