CO2 poisoning effect on HY zeolite dehydration catalyst

The poisoning effect of CO₂ on a HY catalyst for the dehydration of 2-(2-hydroxyethyl)-pyridine (HEP) to 2-vinylpyridine (VP) has been investigated by FT-IR analysis in the presence and absence of pyridine. CO₂ was found to adsorb on sites not occupied by pyridine,i.e. on weak basic sites accompanying the strongly acidic sites, characteristic of Y zeolites in the protonated form. When the basic sites are occupied by preadsorbed CO₂, HEP dehydration cannot take place any more through the minor mechanism, involving a couple of acid-base sites, and the reaction proceeds only through the major mechanism, involving a carbocation intermediate, on Br?nsted acid sites only.     

Three-dimensional nitrogen-doped graphene hydrogel supported Co-CeOx nanoclusters as efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

Benefit from the strong synergistic electronic effect between Co and CeO_x, as well as the strong metalsupport interaction between Co-CeO_x and 3D NGH, the as-synthesized Co-(CeO_x)_0.91/NGH catalyst exhibits excellent catalytic activity toward hydrolysis of ammonia borane, with the turnover frequency (TOF) value of 79.5 min^-1.     

Highly sensitive gas-diffusion sequential injection analysis based on flow manipulation

The present paper describes approaches utilizing the powerful flow manipulation capabilities of sequential injection analysis (SIA) to substantially improve the efficiency of gas-diffusion separation compared to its traditional implementation in flow injection analysis (FIA). Ammonia, ethylamine, diethylamine and triethylamine were used as model analytes in this study. Eleven flow manipulation approaches involving continuous flow, stop-flow, oscillating flow, and the introduction of air bubbles to separate the sample zone from the donor solution were tested. Improvement in sensitivity compared to traditional gas-diffusion FIA exceeding one order of magnitude was achieved. It was observed that this improvement increased with the molecular size of the analyte.     

儿童注意缺陷多动障碍与血铅水平关系的探讨

对 8 0例ADHD患儿进行了血铅水平测定和行为评定 (Conners多动症评分量表 ) ,并设60例对照组。结果表明ADHD组血铅水平为 1 5 7 94± 4 1 1 3μg/L ,对照组为 94 73± 2 9 93μg/L ,其中儿童铅中毒发生率 ,ADHD组为 88 75 % ( 71 /80 ) ,对照组为 4 0 0 0 % ( 2 4 /60 ) ,经统计学处理 ,两组资料均具显著性差异 ;ADHD组经降铅治疗后血铅水平明显下降 ,同时反映ADHD临床症状的Conners评分亦明显下降。提示轻度铅中毒可能是ADHD的病因之一。建议在诊治ADHD时 ,采用相应的检测和治疗手段 ,将有助于ADHD的治疗     

Reduction of core in cage protein for application to electron device

For application to floating nanodots gate memory, ferritin core, ferrihydrite nanodot, array was made and reduced to be conductive. Ammonia plasma treatment was employed to reduce the ferrihydrite cores. X-ray photoelectron spectroscopy analysis confirmed that the plasma treated cores embedded in a SiN film are successfully reduced from ferrihydrite to metal iron. It was elucidated that hydrogen radicals or ions in the plasma combine with oxygen atoms in the core and, consequently, the core is reduced to a conductive state. Transmission electron microscope analysis before and after the treatment showed that the reduced core size was smaller than ferrihydrite core by approximately 2 nm, which is consistent with theoretical calculation of the shrink size accompanying core reduction to α-Fe. The plasma treated cores embedded in SiO₂ film are found to be iron oxides, which indicates that the metal iron nanodots are vulnerable to oxygen and easy to be reoxidized.     

What News in the Surface Chemistry of Bulk and Supported Vanadia Based SCR‐Catalysts: Improvements in their Resistance to Poisoning and Thermal Sintering

This paper reports a short review on the impact of poisoning effects and thermal aging on the reactivity of surface vanadate species on benchmark V₂O₅?WO₃/TiO₂ Selective‐Catalytic‐Reduction catalysts. A renewed interest of this SCR technology is related to its diversification notably as after‐treatment systems to treat the exhaust from Diesel engines with higher running temperature especially when SCR catalysts are coated on Diesel Particulates Filters. Particular attention is also paid to poisoning effects in conjunction with the progressive replacement of fossil fuels by bio‐fuels containing alkaline contaminants which drastically deactivate the catalyst through neutralization of strong acid sites. Most of the investigations show that better insight into the mechanisms of poisoning and aging processes is needed especially to understand the relative sensibility of various vanadate species. This could provide original guidelines to catalyst preparation and or the developments of more stable bulk systems as exemplified.     

Electrical and Sensing Properties of Single‐Walled Carbon Nanotubes Network: Effect of Alignment and Selective Breakdown

The electrical transport and NH₃ sensing properties of randomly oriented and aligned SWNT networks were presented and discussed. The results indicate that aligned SWNT‐FETs have better FET characteristics due to the reduced number of interconnected nodes. This was particularly true as the resistance of the devices increased. Gated electrical breakdown was implemented to selectively remove metallic (m‐) SWNTs, thereby reducing scattering centers. This technique provided significant improvements in FET characteristics resulting in greater on/off ratio (e.g. 10⁴). AC dielectrophoretic alignment followed by selective electrical breakdown of m‐SWNTs can significantly enhance the semiconducting properties of SWNT networks which resulted in highly sensitive sensors.     

Citric acid-loaded W1/O/W2 multiple emulsions efficiently remove colonic ammonia both in vitro and in vivo

Hepatic encephalopathy (HE) is a neuropsychiatric disorder caused by chronic and acute liver diseases. It is believed that ammonia played an important role on the pathogenesis of the disease. Herein, acid-loaded water-in-oil-in-water (W₁/O/W₂) multiple emulsions with over 95% encapsulation efficiency were prepared and used to absorb colonic ammonia. The study of citric acid release from W₁ to W₂ in bulk deionized water indicated that only 17% acid released in 8 hours, which proved the stability of the multiple emulsions and hence prevented the intestine from being irritated by acid burst release. In vitro, the W₁/O/W₂ emulsion could remove around 90% ammonia in 1.5 hours from either the 3 mmol/L ammonia solution or the artificial colonic fluid with 1 and 0.5 mmol/L ammonia without acidifying the artificial colonic fluid. In vivo, compared with lactulose, W₁/O/W₂ emulsions could efficiently reduce the blood ammonia to the similar level in the rat models with HE without increasing the water content in feces. All these results indicated a potential application of W₁/O/W₂ multiple emulsions for the treatment of HE.