化学镀Ni-W-P/Pr2O3镀层腐蚀电化学行为

采用极化曲线法和交流阻抗法研究了化学镀Ni-W-P/Pr2O3镀层在3.5%(质量分数)NaCl水溶液中的电化学腐蚀行为.极化曲线结果表明,化学镀Ni-W-P/Pr2O3镀层的自腐蚀电流(2.977 μA/cm2)远远小于Ni-P镀层(10.11 μA/cm2),说明Ni-W-P/Pr2O3的耐蚀性能比Ni-P镀层好.交流阻抗试验结果表明,Ni-W-P/Pr2O3镀层在整个浸泡过程中仅出现一个时间常数的单容抗弧,且随着腐蚀时间的增长,镀层电阻也在增大.     

ZM5镁合金化学镀Ni-P合金镀层的电化学腐蚀行为

在ZM5镁合金表面制备了化学镀Ni-P合金镀层,并对其微观形貌、成分、相结构及电化学腐蚀行为进行了分析。结果表明:化学镀Ni-P合金镀层的厚度约为25μm,表面均匀、平整,内部致密无缺陷,与基体结合紧密,其结构为非晶态。与ZM5镁合金基体相比,化学镀Ni-P合金镀层的自腐蚀电位正移了1.171 V,自腐蚀电流密度减小了近3个数量级,表现出良好的耐蚀性。化学镀Ni-P合金镀层在阴极极化电位和自腐蚀电位下的阻抗谱均由两个容抗弧半圆组成,表现为均匀腐蚀。而阳极电位下化学镀Ni-P合金镀层的阻抗谱由容抗弧和Warburg阻抗组成,表现为局部腐蚀。化学镀Ni-P合金镀层在自腐蚀电位和阴极极化电位下工作能显著提高耐蚀性,并且在自腐蚀电位下的耐蚀性更好。而化学镀Ni-P合金镀层在阳极极化电位下的耐蚀性较差,不利于镀镍镁合金的长期使用。     

钢基体的Ni-P和Ni-Cu-P合金镀层的性能研究

对比了Ni-P合金镀层和Ni-Cu-P合金镀层的耐蚀性及硬度。研究了热处理温度及保温时间对两种镀层耐蚀性的影响。结果表明:与Ni-P合金镀层相比,Ni-Cu-P合金镀层表面更加致密,耐蚀性更好;当热处理温度为200~300℃时,Ni-P合金镀层和Ni-Cu-P合金镀层的硬度均随保温时间的延长而增大;当热处理温度为400℃时,Ni-P合金镀层和Ni-Cu-P合金镀层的硬度均随保温时间的延长先增大后减小。     

化学镀镍磷合金的耐蚀性

采用化学镀方法制取Ni-P非晶合金镀层。测定了镀层的耐蚀性和极化曲线,研究了热处理对非晶态Ni-P合金耐蚀性能的影响。结果表明:在非氧化性酸及中性介质中,Ni-P非晶合金镀层具有优良的耐蚀性,热处理使其耐蚀性降低。     

化学镀Ni-P合金镀层在低温模拟海水中的腐蚀性能

为了改善Q235钢在低温海水中的耐蚀性,在Q235钢表面化学镀Ni-P合金镀层。采用显微镜观察了镀层的表面形貌,采用X射线衍射仪分析了镀层的结构,并通过浸泡试验、极化曲线和电化学阻抗等方法考察了Q235钢和镀层在5℃的模拟海水中的耐蚀性。结果表明:化学镀Ni-P合金镀层表面的胞状物分布较为均匀,镀层为非晶态结构,镀层在低温海水中的腐蚀速率约为Q235钢的1/5。这主要与该镀层在海水中能够发生钝化及镀层表面较为致密有关。     

Ni-Cu-P化学镀层表面铁细菌污垢特性

利用化学镀Ni-Cu-P工艺对换热器常用材料低碳钢进行改性,研究Ni-Cu-P镀层表面铁细菌污垢特性。将试样置于铁细菌悬液中进行为期5天的污垢沉积实验,记录Ni-Cu-P镀层表面铁细菌污垢沉积量、腐蚀失重量以及铁细菌生长变化情况,分析铁细菌污垢实验前后镀层表面微观形貌。测试不同时间的极化曲线和电化学阻抗谱,定性分析极化曲线和阻抗谱的变化规律,采用Zsimp Win拟合出最佳等效电路模型。研究结果表明,Ni-Cu-P镀层可以有效抑制微生物污垢生长,与未施镀的碳钢试样对比,Ni-Cu-P改性表面污垢沉积量减少89.1%,表面失重量减少80.2%。Ni-Cu-P镀层自腐蚀电位高于碳钢,自腐蚀电流密度比碳钢小,且容抗弧半径大于碳钢,展现了较好的耐蚀性。铁细菌对Ni-Cu-P镀层的腐蚀速度先减小后增大,在12h腐蚀速度最小。     

芳纶纤维Ni-P/Ni-Cu-P双层化学镀的结构与形貌

采用化学镀技术,实现了芳纶纤维表面化学镀Ni-P/Ni-Cu-P的金属化处理,利用SEM、EDS和XRD分别对芳纶纤维原始样品、粗化后、施镀后及剥落层的表面形貌、镀层的成分和物相进行了分析比较,并对镀层的形成机制及剥落原因进行了分析研究。结果表明:经过预处理的芳纶纤维比表面积增大,增加了其亲水性和活性;化学镀Ni-P/Ni-Cu-P后,Ni-P镀层中镍含量降低,磷含量增多,纯镍转化为Ni₃P且伴随有少量的铜的出现,整体镀层中Ni、Cu、P的原子比为8.54:3.66:5.59,镀层中以纯Cu、Cu₃P和Ni₃P为主;另外由于镀层中应力分布不均,以及P在Ni-P/Ni-Cu-P相界面的偏聚,削弱了界面的结合强度,使局部拉应力集中,造成了镀层的剥落;且化学镀铜是依靠镍离子的催化作用形成镀层的。     

化学镀Ni-P合金镀层铬酸盐钝化及其耐蚀性的研究

对化学镀Ni-P合金镀层进行铬酸盐钝化处理,并研究了钝化温度和钝化时间对化学镀NiP合金镀层耐蚀性的影响。结果表明:钝化处理可以显著提高化学镀Ni-P合金镀层的耐蚀性。经40g/L重铬酸钾钝化的化学镀Ni-P合金镀层的耐蚀性明显优于经5g/L重铬酸钾钝化的化学镀Ni-P合金镀层的耐蚀性。随着钝化温度的升高或钝化时间的延长,化学镀Ni-P合金镀层的耐蚀性增强。     

阴离子对化学镀Ni-Cu-P合金耐蚀性的影响

采用化学镀工艺在铜基体表面沉积Ni-Cu-P镀层,利用扫描电镜(SEM)和电子能谱(EDX)对Ni-Cu-P镀层的形貌和成分进行了分析。同时,采用极化曲线(PC)和交流阻抗(EIS)研究了常温下Ni-Cu-P镀层在0.1 mol/L,0.001 mol/L的NaCl,Na2SO4,NaNO3和NaNO2电解质中的耐蚀性能。结果表明,在较高浓度下,氯离子和硫酸根离子的活性吸附作用能够促进镀层中Ni的溶解,从而也加速了镀层的表面钝化,在较低浓度下,氯离子和硫酸根离子的活性吸附作用减弱,镀层很难钝化;硝酸根离子和亚硝酸根离子在高浓度和低浓度下均很难使镀层钝化。     

机械传动轴基体化学镀Ni-P合金镀层

在机械传动轴用40Cr钢基体上制备了化学镀Ni-P合金镀层,并对化学镀Ni-P合金镀层的厚度、表面粗糙度、结构、表面形貌及耐蚀性进行了研究。结果表明:化学镀Ni-P合金镀层属于立方结构,结晶度较好;化学镀Ni-P合金镀层表面呈现出均匀、致密的颗粒状形貌,厚度约为6.5 pm;化学镀Ni-P合金镀层的自腐蚀电位为一0.305 V,自腐蚀电流密度为36.72 ptA/cm2,耐蚀性较好。     

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。