DNA sequencing with titanium nitride electrodes

We construct a hydrogen‐bond based metal–molecule–metal junction, which contains two identical “reader” molecules, one single DNA base as a bridged molecule, and two titanium nitride electrodes. Hydrogen bonds are formed between “reader” molecules and DNA base, whereas titanium–sulfur bonds are formed between “reader” molecules and titanium nitride electrodes. We perform electronic structure calculations for both the bare bridged molecule and the full metal–molecule–metal system. The projected density of states shows that when the molecule is connected to the titanium nitride electrode, the energy levels of the bridged molecule are shifted, with an indirect effect on the hydrogen bonds. This is similar to the case for a gold electrode but with a more pronounced effect. We also calculate the current–voltage characteristics for the molecular junctions containing each DNA base. Results show that titanium nitride as an electrode can generate distinct conductance for each DNA base, providing an alternative electrode for DNA sequencing. © 2013 Wiley Periodicals, Inc.     

Reaction of 2,3-Epoxypropyl Ethers with 1-Butanol

Nucleophilic opening of the oxirane ring in 2,3-epoxypropyl ethers with alcohols in the presence of titanium alkoxides and other catalysts was studied. The mechanism of catalysis by titanium alkoxides was discussed on the basis of comparison with acid–base catalysts.     

钛硅分子筛TS-1的合成、表征及催化性能

钛硅分子筛TS-1自Taramasso等［1］首次报道合成以来,由于其优异的选择氧化催化 性能及其催化的反应具有对环境污染轻,反应条件温和等优点而备受关注. 钛硅分子筛的制 备及应用研究是分子筛催化领域中的热点之一. 在经典的合成体系中,四丙基氢氧化铵(TPAO H)常被用作模板剂［2］,这是钛硅分子筛价格较为昂贵的主要原因之一. 国内外学者 都致力于廉价合成体系的开发,Müller等［3］报道了以四丙基溴化铵(TPABr)作模板 剂合成钛硅分子筛. 对于钛源和硅源,人们往往都采用水解趋势较为缓和的钛酯和硅酯,以达 到钛源和硅源的匹配;在合成过程中,要预先将钛酯加入到乙酰丙酮或异丙醇溶剂中进行稀释 ,并对胶液进行蒸醇处理［2,3］. 这使得钛硅分子筛的合成过程更加复杂,并提高了 其合成费用. 本文以钛酸四丁酯(TBOT)和四氯化钛混合原料作钛源,成功地合成出对丙烯环 氧化具有优异催化性能的钛硅分子筛TS-1,避免了上述的复杂步骤,并降低了钛硅分子筛的成本.     

The polarography of molybdenum,titanium and niobium in solutions of organic acids

Further work on the polarographic reduction of molybdenum(VI), niobium(V) and titanium(IV) in base electrolytes containing organic acids is reported. A base electrolyte of 0.5 M citric acid-0.025 M sulphuric acid-0.05 M thorium nitrate proved suitable for the determination of molybdenum and titanium in the presence of niobium, tantalum, tungsten and zirconium. A direct polarographic method using this base electrolyte is described for the determination of molybdenum in a niobium base alloy.     

Fabrication of a titanium anode with an active coating based on mixed oxides of base metals

Possibility of fabricating a titanium anode with an active coating based on mixed oxides of base metals by using an asymmetric ac current was analyzed.     

钛硅分子筛中铝杂质对其性能的影响

 以四丙基溴化铵为模板剂,以硅溶胶为硅源,采用水热合成法制备了不同铝杂质含量的钛硅分子筛,并系统考察了铝杂质对钛硅分子筛性能的影响．结果表明,原料中的铝杂质可促进钛硅分子筛晶化,但同时也引入了酸性中心;在丙烯环氧化反应中,铝杂质形成的酸性中心会催化环氧丙烷与溶剂的副反应;加入少量碱性添加物可抑制铝杂质的酸催化作用,提高环氧丙烷的选择性,但过量碱性添加物会使钛硅分子筛失活．     

Titanium-salen complexes as initiators for the ring opening polymerisation of rac-lactide

A family of bis(iso-propoxide) titanium(IV) complexes supported by tetradentate Schiff base (salen) ligands has been synthesised and characterised, including a structural determination of N,N'-bis(6'-methylenimino-2',4'-di-tert-butylphenoxy)cyclohexyl-(1R,2R)-diamino titanium(IV) bis(iso-propoxide). Their suitability for initiating the ring-opening polymerisation of rac-lactide has been investigated. Polymerisation activities are shown to correlate with the electronic properties of the substituents within the salen ligand. In contrast to aluminium-salen initiators, electron-withdrawing substituents on the Schiff base ligand have a detrimental influence upon polymerisation activities, whereas the use of electron-donating alkoxy-functionalized ligands has allowed the highest recorded activity to date for a titanium-based initiator.     

Synthesis of Titanium (IV) Complexes with Schiff‐base Ligand and Their Catalytic Activities for Polymerization of Ethylene and Styrene

Reaction of titanium (IV) isopropoxide with the unusual land of Shiff‐base in 1:1 molar ratio gives a variety of new derivatives of titanium (IV) in high yield. These complexes were characterized by elemental analyses, IR, MS and ¹H NMR. It was noteworthy to find that all these complexes were active for polymerizations of ethylene and styrene when activated by a Lewis acid cocatalyst (MAO).     

Highly enantioselective hetero-Diels-Alder reaction of Brassard diene with aromatic aldehydes

[reaction: see text] Hetero-Diels-Alder reactions of Brassard diene with aromatic aldehydes were carried out smoothly in the presence of titanium(IV) tridentate Schiff base complexes to give the corresponding chiral delta-lactones in high enantioselectivities (up to 99% ee) under mild conditions.     

An efficient solvent free catalytic oxidation of sulfides to sulfoxides with hydrogen peroxide catalyzed by a binaphthyl-bridged Schiff base titanium complex

A titanium binaphthyl-bridged Schiff base complex proved to be an efficient catalyst for the hydrogen peroxide oxidation of aromatic and aliphatic sulfides to the corresponding sulfoxides in satisfactory yields under solvent-free conditions.     

Specific features of etching of ultrafine- and coarse-grained titanium in base and acid solutions of hydrogen peroxide

The character and kinetics of chemical etching of nanostructured titanium in base (NH₄OH/H₂O₂) and acid (H₂SO₄/H₂O₂) solutions of hydrogen peroxide (Piranha) were studied. A study of the etching kinetics showed that the etching rate of the nanostructured titanium is not constant and tends to decrease, but in the case of the sulfuric acid solution the decrease is smoother owing to the growth of the oxide layer. The etching rate for ultrafine-grained titanium is higher than for the coarse-grained sample. The applied significance of the study is associated with the fact that Piranha solutions show promising for cleaning, hydrophilizing, and making rough the titanium surface for use in medical implants.     

Direct vapor phase propylene epoxidation over deposition-precipitation gold-titania catalysts in the Presence of H2/O2: Effects of support, neutralizing agent, and pretreatment

The effects of titanium connectivity, deposition solution neutralizing agent, and catalyst pretreatment were examined for a series of Au-on-titanium-containing supports for the direct gas-phase epoxidation of propylene using hydrogen and oxygen. The degree of titanium isolation was examined using pure titania, monolayer-titania on silica, submonolayer-titania on silica, and titanium silicalite-1 (TS-1) supports. Activity and selectivity were shown to increase as the degree of titanium isolation increased, with TS-1 and submonolayer-titania supports providing the best stability and yield. Isolation of the titanium was found to significantly reduce the cracking of propylene to ethanal and carbon dioxide. Sodium carbonate was found to be the best neutralizing agent for catalysts prepared using deposition-precipitation (DP). DP with ammonium hydroxide gave catalysts with reduced selectivity and activity. Titania-modified silica was found to produce better catalysts when the support was not calcined prior to gold deposition. Similarly, calcination was detrimental to catalysts prepared via deposition of a 2 nm gold colloid onto titania-modified supports even though the gold did not sinter. The beneficial effects of Ti site isolation and support acid/base control are best seen at higher temperatures, where only a few catalysts can maintain selectivity.     

低价钛试剂促进下2-(2-硝基苯基)咪唑与席夫碱的反应

在低价钛试剂作用下,以四氢呋喃为溶剂,研究了2-(2-硝基苯基)咪唑与席夫碱的分子间还原偶联反应.结果发现席夫碱中C-N键的断裂优于其与硝基的偶联成环,生成了5,6-二氢化咪唑并[1,2-c]喹唑啉.     

Organic‐Base‐Driven Intercalation and Delamination for the Production of Functionalized Titanium Carbide Nanosheets with Superior Photothermal Therapeutic Performance

The delamination of titanium carbide sheets, an intriguing class of two‐dimensional materials, has been critically dependent on the extraction of interlayer Al in acidic media, such as concentrated hydrofluoric acid (HF) or a mixture of hydrochloric acid (HCl) and a fluoride salt. Herein, we report an organic‐base‐driven intercalation and delamination of titanium carbide that takes advantage of the amphoteric nature of interlayer Al. The resulting aluminum‐oxoanion‐functionalized titanium carbide sheets manifested unusually strong optical absorption in the near‐infrared (NIR) region with a mass extinction coefficient as high as 29.1 L g^?1 cm^?1 at 808 nm. Thus, the performance of this material is comparable or even superior to that of state‐of‐the‐art photoabsorption materials, including gold‐based nanostructures, carbon‐based materials, and transition‐metal dichalcogenides. Preliminary studies show that the titanium carbide sheets serve as efficient photothermal agents against tumor cells.     

Oligomerization of Dicyclopentadiene Fraction Using Monosubstituted Titanium Chloride as a Catalyst

The purpose of this study is to investigate the dicyclopentadiene fraction of liquid pyrolysis product oligomerization with the use of the modified catalytic system based on titanium alkoxides. The choice of reaction catalyst is specified by searching the ways of obtaining petroleum resins with the improved performance characteristics and the possibility of low-temperature polymerization. The use of monosubstituted titanium chloride as a catalyst allows obtaining light resins, films on the base of which are smooth, glossy and have good technical characteristics: adhesion 1 point, resilience <1 mm, impact resistance >10 cm.     

Detitanation of MgCl2‐supported Ziegler‐Natta catalysts for the study of active sites organization

Thermal treatments under vacuum of conventional supported Ziegler‐Natta precatalysts (MgCl₂/TiCl₄/Dibutylphthalate) were conducted to gradually remove titanium to modify the active sites distribution. Only limited detitanations of precatalysts were achieved paying attention not to chemically alter the internal donor (T < 150 °C). Used in combination with the required cocatalyst and external donor in the propylene slurry polymerization, the modified precatalysts exhibited a drop of activity versus decreasing titanium content but the distributed polymer properties are almost not affected (a slight narrowing of molecular weight distribution was observed). After a titanium chloride secondary impregnation (possibly done in presence of an additional Lewis base), activity resumed but polymer properties are once again unchanged. These findings highlight the difficulty to separate the different families of active sites and lead us to propose a cluster organization of titanium active sites. Active sites are composed of titanium clusters having a size distribution at the precatalyst surface, possessing a critical operating size and operating collectively in polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5461–5470, 2008     

聚醋酸乙烯类梳型分散剂的制备与表征

颜料在工业生产和人们的日常生活中起着重要的作用.由于颜料颗粒具有较大的比表面积和较高的比表面能,是热力学不稳定体系,当分散在介质中时容易发生团聚,影响其特性的发挥[1],因此需加入分散剂使其在分散介质中稳定分散.     

An indirect complexometric method for determination of tin in alloys

A simple and fast complexometric method for the determination of tin in alloys is presented. It is based on the initial complexation of tin with EDTA and its subsequent decomposition with mercaptosuccinic acid. Interference of ions normally encountered in determination of tin was studied. The method has been used for the analysis of alloys such as bronzes, solders, white metal and titanium base alloys.     

Bifunctional Schiff base/Ti(IV) catalysts for enantioselective cyanoformylation of aldehydes with ethyl cyanoformate

A new bifunctional titanium/Schiff base catalyst was developed for the enantioselective cyanoformylation of aldehydes with ethyl cyanoformate. The reaction proceeded smoothly with a mild reaction condition to afford the cyanohydrin ethyl carbonates in high yields (up to 96%) and good enantioselectivities (up to 85% enantiomeric excess). Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of the Phase of Titanium Oxide on Metal-Support Interaction

The metal-support interaction in the system of platinum supported on titanium oxides of different crystalline structures was investigated. Titanium oxide powders used as supports were prepared by neutralization of TiOCl₂-analogue solution with either NaOH or NH₃ base at varied pH. Pt was introduced onto the supports by impregnation. The phenomenon of strong metal-support interaction (SMSI) was determined by the suppression of chemisorption of H₂ over samples reduced at 773 K, in comparison with the behavior of samples reduced at 473 K. The loss of adsorption capacity was proved not due to metal sintering by examining the recovery of adsorption capacity after reduction, reoxidation and reduction cycle, accompanied with examination of the size of Pt particle with an x-ray diffractiometer and a transmission-electron microscope. The results showed that SMSI phenomenon was common to Pt supported on titanium oxides of all the varied crystalline structures. However, the chemisorption capacity of Pt reduced at 473 K varied greatly with the sodium content in the supports, which in turns affects the crystalline structure of titanium oxide. These results are attributed mainly to electronic effect endowed by the support.