硅肥中有效硅含量的测定方法研究

采用氟硅酸钾容量法对硅肥中测定有效硅含量的实验条件进行了研究。氟硅酸钾容量法能够准确、快速、简便测定硅肥中有效硅含量。推荐沉淀冷却时间应控制在30min以上;沉淀的洗涤温度应控制在15℃以下;滴定指示剂可选用酚酞;通过对氟硅酸钾分析纯的水解,验证此方法水解完全。     

水平振荡——红外分光光度法测定城市污泥中矿物油

对测定污泥中矿物油的预处理方法和萃取剂进行优化和比较,用四氯乙烯替换四氯化碳作为萃取剂,采用水平振荡法代替索氏提取法从污泥中提取矿物油,并对水平振荡器频率和振荡时间进行研究。结果表明,振荡频率在200r/min,振荡时间为30min时为最佳试验条件。在此基础上于原方法进行比对,验证了用四氯乙烯-水平振荡萃取污泥中矿物油方法可行,且操作简单,精密度、回收率高。     

用正交试验法研究粉煤灰硅肥料制备工艺

采用正交试验法,以KOH和几种盐为活化剂,研究用粉煤灰制备硅肥料时粉煤灰粒度、炉温、焙烧时间、碱度对硅肥中有效硅含量的影响。研究结果表明,粉煤灰粒度、炉温、碱度对有效硅含量影响明显,加热时间影响较小。适当控制工艺条件,以KOH或K2CO3/CaCO3为活化剂可使有效硅含量提高30倍。     

络合滴定法测定硅含量的初探

在硅酸盐化学分析中,对硅元素含量测定的传统方法是重量法或中和滴定法。重量法是用过量的盐酸生成 H_2SiO_3沉淀,过滤洗涤沉淀后,置高温电炉灼烧得到 SiO_2,再进行称量计算。此方法操作时间长,手续复杂,需两次进高温电炉(950℃)灼烧。中和滴定法是用氢氟酸将硅酸盐原料中的硅转化成 K_2SiF_6,经水解后,采用中和滴定的方法测定。此方法在操作时要接触毒害试剂HF,需要在通风厨中进行,使用仪器要采用塑料制品。有些条件对于中小型硅酸盐工业企业,目前还不具备。因此,笔者试用络合滴定法对硅含量进行了测定,取得了令人满意的结果。     

工业硅中硅含量的测定

介绍了用氢氟酸重量法直接测定工业硅中硅含量的方法。试样用硝酸和氢氟酸分解,使硅生成四氟化硅除去。然后进入高温炉中灼烧。根据氢氟酸处理前后的质量差,扣除铁氧化成三氧化二铁的增量,计算硅的质量百分数。本方法的相对标准偏差小于0.20%。     

混凝土用硅灰粒度分布参数检测条件的研究

为了准确快速测量混凝土用硅灰的粒度分布,以中位径(D50)和粒度分布曲线为评价指标,采用激光粒度仪系统研究了分散剂种类、分散剂浓度、硅灰在介质中浓度、超声分散时间、分散温度以及超声分散频率对硅灰检测结果的影响.结果表明,激光粒度分析仪适用于硅灰粒度分布的检测,且具有高度重复性.六偏磷酸钠和十二烷基苯磺酸钠对硅灰具有显著的分散效果,六偏磷酸钠作为硅灰分散剂的最佳浓度为0.5～1.1 g/L.未使用分散剂时,硅灰最佳分散条件为5 ～ 15 g/L分散浓度、10 min分散时间、40℃分散温度和40 kHz分散频率;六偏磷酸钠加入后,硅灰最佳分散条件为5 ～30 g/L分散浓度、5 min分散时间、20℃分散温度和32 kHz分散频率.     

微孔-介孔钛硅氧化物复合材料的合成与表征

以十六烷基三甲基溴化铵为模板剂诱导硅酸钠水解形成的多孔二氧化硅为硫酸钛水解的"模板",用溶胶-凝胶技术和水热处理工艺合成钛硅复合材料前驱体.通过两步灼烧法可脱除前驱体中的有机模板.通过x射线衍射、差热分析和低温氮吸附等测试技术对产物进行表征.结果表明:硅浓度约为0.1 mol/L,起始钛浓度约为0.125mol/L,pH值为1时,硫酸钛于室温下水解制备的前驱体具有较好的孔结构.前驱体首先在350℃灼烧4h,再在750℃灼烧4h后的产物为晶体结构趋于规整的锐钛矿型二氧化钛,比表面积高达369m2/g,并具有良好的热稳定性.通过t-曲线计算出微孔和介孔对比表面及孔体积的贡献.     

硅钼蓝分光光度法测定化肥中可溶性硅含量

化肥中可溶性硅含量(以SiO2计)的测定,通常采用重量法和氟硅酸钾容量法(常量分析).重量法准确度高,但操作步骤繁琐;氟硅酸钾容量法对测定环境条件及操作条件要求高,用其测定低含量的SiO2容易引起较大的分析误差.笔者引入硅钼蓝分光光度法测定二氧化硅的实际含量,可解决重量法和氟硅酸钾容量法中实验要求高、测定低含量SiO2时容易出现误差大的问题.     

响应面法优化电解锰渣的微波活化有效硅工艺条件

采用单因素实验和响应面实验方法,对微波焙烧提高电解锰渣(EMR)中有效硅含量的活化条件进行优化研究.首先采用单因素法研究了焙烧温度、焙烧时间、微波功率和助剂比例(Na2 CO3与EMR的质量比)对EMR中有效硅含量的影响,然后利用响应面法探讨了各因素及其交互作用对EMR中有效硅含量的影响,确定了微波焙烧提升EMR中有效硅含量的最佳工艺条件为:焙烧温度854℃,焙烧时间43 min,微波功率2608 W,助剂比例0.55.在该工艺条件下,有效硅含量可达18.16％,试验值与模型预测值的误差只有0.11％.采用回归分析法,通过实验验证了响应面优化得到的二次多项式模型是合理可靠的.同时,硅的微波活化工艺为电解锰渣的资源化利用提供新思路.     

工业硫磺中有机物含量的测定

对灼烧重量法、氯仿提取重量法和总碳法三种测定方法作了对比试验。表明:总碳法的准确度和精密度均最优,且最省时,一般2.5～3.5h可完成一次测定。故工业硫磺国家标准中应采用此法,但用作吸收液的Ba(OH)_2溶液应作空白试验。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。