Hydro­gen bonds in the framework of bis{2-[bis(2-amino­ethyl)­amino]­ethanol}nickel(II) diperchlorate

The title molecule, [Ni(C₆H₁₇N₃O)₂](ClO₄)₂, possesses a crystallographic centre of symmetry at the Ni^II position. The coordination geometry around the Ni^II atom is distorted octahedral, consisting of six N atoms from two tripodal poly­amine ligands, while the ethanol O atoms of the ligands remain uncoordinated. The crystal packing shows two-dimensional layers and an infinite three-dimensional framework which is stabilized by a hydrogen-bonded network.     

On the influence of the solute sample size on temperature-programmed retention indices

The effect of the solute sample size on the measurement of temperature-programmed retention indices (I_TP) has been studied on glass capillary columns with different stationary phases, film thicknesses, and temperature programs. The sample capacity of a solute is little affected by the parameters of temperature program, i. e. initial temperature and heating rate. However, it has been found that in a temperature programmed run, allowable sample sizes for high I_TP values are lower than for low I_TP values. About 10 ng of each compound is recommended as the sample size for accurate measurement of I_TP values on commonly used capillary columns.     

Combustion kinetics and structural features of bituminous coal before and after modification process

Coal modification process is becoming popular to be used to upgrade coal quality. The upgraded coal (semi-coke) can be utilized in ironmaking process. Thermogravimetry and DAEM were used to analyze the combustion kinetics of bituminous coal before and after modification in this study. To understand the factors influencing the combustion process, various advanced techniques including X-ray diffraction analysis, Raman spectroscopy and Fourier transform infrared spectroscopy were adopted to investigate the structural features of the combusted samples. The results showed that the coal aromaticity increases significantly with the side-chains and chain length reduced, while the matrix structure transforms to graphite-like structure after the modification process. Those structural changes lead to the decrease in coal reactivity, thus weakening the coal combustion performance.     

High throughput tryptic digestion via poly (acrylamide-co-methylenebisacrylamide) monolith based immobilized enzyme reactor

A poly (acrylamide-co-methylenebisacrylamide) (poly (AAm-co-MBA)) monolith was prepared by thermal polymerization in the 100 or 250 μm i.d. capillary. The monolithic support was activated by ethylenediamine followed by glutaraldehyde. Trypsin was then introduced to form an immobilized enzyme reactor (IMER). The prepared IMER showed a reliable mechanical stability and permeability (permeability constant K = 2.65 × 10⁻¹³ m²). With BSA as the model protein, efficient digestion was completed within 20 s, yielding the sequence coverage of 57%, better than that obtained from the traditional in-solution digestion (42%), which took about 12 h. Moreover, BSA down to femtomole was efficiently digested by the IMER and positively identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). To test the applicability of IMER for complex sample profiling, proteins extracted from Escherichia coli were digested by the IMER and further analyzed by nanoreversed phase liquid chromatography-electrospray ionization-mass spectrometry (nanoRPLC-ESI-MS/MS). In comparison to in-solution digestion, despite slightly fewer proteins were positively identified at a false discovery rate (FDR) of ∼1% (333 vs 411), the digestion time used was largely shortened (20 s vs 24 h), implying superior digestion performance for the high throughput analysis of complex samples.     

Preparation and characterization of attapulgite-silver nanocomposites,and their application to the electrochemical determination of nitrobenzene

Microchimica Acta - The surface of attapulgite was cleaned, modified with 3-aminpropyltriethoxysilane, and then covered with silver nanoparticles. The structure and morphology of the modified...     

Unusual enhancement in electrical conductivity of tin oxide thin films with zinc doping

Electrical conductivity of SnO(2)-based oxides is of great importance for their application as transparent conducting oxides (TCO) and gas sensors. In this paper, for the first time, an unusual enhancement in electrical conductivity was observed for SnO(2) films upon zinc doping. Films with Zn/(Zn + Sn) reaching 0.48 were grown by pulsed spray-evaporation chemical vapor deposition. X-Ray diffraction (XRD) shows that pure and zinc-doped SnO(2) films grow in the tetragonal rutile-type structure. Within the low doping concentration range, Zn leads to a significant decrease of the crystallite size and electrical resistivity. Increasing Zn doping concentration above Zn/(Zn + Sn) = 0.12 leads to an XRD-amorphous film with electrical resistivity below 0.015 ? cm at room temperature. Optical measurements show transparencies above 80% in the visible spectral range for all films, and doping was shown to be efficient for the band gap tuning.     

A novel fluorescent aptasensor for thrombin detection: using poly(m-phenylenediamine) rods as an effective sensing platform

In this communication, we develop a novel fluorescent aptasensor for thrombin detection with the use of poly(m-phenylenediamine) (PMPD) rods as an effective sensing platform. This aptasensor exhibits extraordinarily high sensitivity with a detection limit as low as 100 pM and excellent selectivity.     

Preparation of Ag nanoparticle-decorated poly(m-phenylenediamine) microparticles and their application for hydrogen peroxide detection

The chemical oxidation polymerization of m-phenylenediamine (MPD) by ammonium persulfate (APS) at room temperature results in the formation of poly(m-phenylenediamine) (PMPD) microparticles. The subsequent treatment of such microparticles with an aqueous AgNO(3) solution produces Ag nanoparticle (AgNP)-decorated PMPD microparticles. It was found that as-formed AgNPs exhibited remarkable catalytic performance toward the reduction of hydrogen peroxide (H(2)O(2)). The enzymeless H(2)O(2) sensor constructed with such composites showed a fast amperometric response time of less than 5 s, and the corresponding linear range and detection limit were estimated to be from 0.1 to 30 mM and 4.7 μM, respectively, at a signal-to-noise ratio of 3.     

Strong deaggregating effect of a novel polyamino resorcinarene surfactant on gold nanoaggregates under microwave irradiation

Gold nanoparticles were prepared by ethylene glycol (EG) reducing gold chloride under microwave irradiation. The EG-stabilized gold colloids varied from red to blue with increasing amounts of EG, due to particle aggregation. Addition of the macrocyclic polyamine 2,8,14,20-tetranonyl-4,6,10,12,16,18,22,24-octa(1-aminoethylcarbamoyl)methoxyresorcinarene (TNMR) reversed nanoparticle aggregation under microwave irradiation and greatly improved their dispersion stability in aqueous solutions. These effects are likely due to the amphiphilic nature of TNMR, which has a large hydrophilic headgroup with eight amino groups and four hydrophobic chains. Moreover, the large and flexible hydrophilic groups containing more N and O atoms in the TNMR molecule has a strong stretching and penetrating ability in the aqueous solution, and TNMR molecules can easily form a bilayer protecting structure on the surface of gold nanoparticles, which plays a critical role in the color-change process of the EG-stabilized gold colloid.