DESIGN AND PERFORMANCE OF TWO ORTHOGONAL EXTRACTION TIME-OF-FLIGHT SECONDARY ION MASS SPECTROMETERS FOR FOCUSED ION BEAM INSTRUMENTS

The design and performance of two orthogonal extraction time-of-flight mass spectrometers are reported that were adapted to existing focused ion beam microscopes for secondary ion mass spectrometry. The performances of these designs were compared to that of a prototype previously described by our group. The differences include newly designed transfer ion optics and in the use of a larger microscope chamber. The two new prototypes allow a mass resolving power of either 600 Th/Th (compact design) or 3000 Th/Th (high resolution design) while simultaneously achieving a lateral spatial resolution of less than 50 nm. The spectrometers and their performance (effective ion yield, mass resolving power, lateral, and depth resolution) are described and compared. Additionally, example applications are presented with multivariate statistical methods to visualize the data sets. Both time-of-flight mass analyzers use orthogonal extraction which avoids the need to pulse the primary ion beam, and the of use monoisotopic gallium to preserve the mass resolution. The goal of the design was a cost-effective accessory to augment typical focused ion beam-scanning electron microscopy applications as an alternative to the cost of a dedicated secondary ion mass spectrometer. The modified instrument allows excellent non destructive imaging and easy sample access, and benefits from the presence of complementary non destructive analytical and imaging techniques that exploit the presence of an electron microscope.     

Real-world emission factors of fine and ultrafine aerosol particles for different traffic situations in Switzerland

Extended field measurements of particle number (size distribution of particle diameters, D, in the range between 18 nm and 10 microm), surface area concentrations, and PM1 and PM10 mass concentrations were performed in Switzerland to determine traffic emissions using a comprehensive set of instruments. Measurements took place at roads with representative traffic regimes: at the kerbside of a motorway (120 km h(-1)), a highway (80-100 km h(-1)), and in an urban area with stop-and-go traffic (0-50 km h(-1)) regulated by light signals. Mean diurnal variations showed that the highest pollutant concentrations were during the morning rush hours, especially of the number density in the nanoparticle size range (D <50 nm). From the differences between up- and downwind concentrations (or differences between kerbside and background concentrations for the urban site), "real-life" emission factors were derived using NOx concentrations to calculate dilution factors. Particle number and volume emission factors of different size ranges (18-50 nm, 18-100 nm, and 18-300 nm) were derived for the total vehicle fleet and separated into a light-duty (LDV) and a heavy-duty vehicle (HDV) contribution. The total particle number emissions per vehicle were found to be about 11.7-13.5 x 10(14) particles km(-1) for constant speed (80-120 km h(-1) and 3.9 x 10(14) particles km(-1) for urban driving conditions. LDVs showed higher emission factors at constant high speed than under urban disturbed traffic flow. In contrast, HDVs emitted more air pollutants during deceleration and acceleration processes in stop-and-go traffic than with constant speed of about 80 km h(-1). On average, one HDV emits a 10-30 times higher amount of particulate air pollutants (in terms of both number and volume) than one LDV.     

面粉厂的能量管理

全球能源价格的增长正在再一次使粮食加工工业对其增值工序的能耗问题变得敏感.由于能耗占面粉加工总成本高达6%,因而面粉和粗粒粉的加工厂关心探索降低能量需求的新的解决办法. 为了获得解决能量管理问题的办法,工序链内部能量需求的分析是重要的.目的是要证明用来削减能耗的投资在什么地方是会收到效果的,而在工厂哪些区段的能量消耗只属于边际重要性.     

Removal of estrogenic activity and formation of oxidation products during ozonation of 17alpha-ethinylestradiol

This study investigated the oxidation of the oral contraceptive 17alpha-ethinylestradiol (EE2) during ozonation. First, the effect of ozone (O3) on the estrogenic activity of aqueous solutions of EE2 was studied using a yeast estrogen screen (YES). It could be shown that O3 doses typically applied for the disinfection of drinking waters were sufficient to reduce estrogenicity by a factor of more than 200. However, it proved impossible to completely remove estrogenic activity due to the slow reappearance of 0.1-0.2% of the initial EE2 concentration after ozonation. Second, oxidation products formed during ozonation of EE2 were identified with LC-MS/MS and GC/MS and the help of the model compounds 5,6,7,8-tetrahydro-2-naphthol (THN) and 1-ethinyl-1-cyclohexanol (ECH), which represent the reactive phenolic moiety and the ethinyl group of EE2. Additionally, oxidation products of the natural steroid hormones 17beta-estradiol (E2) and estrone (E1) were identified. The chemical structures of the oxidation products were significantly altered as compared to the parent compounds, explaining the diminished estrogenic activity after ozonation. Overall,the results demonstrate that ozonation is a promising tool for the control of EE2, E2, and E1 in drinking water and wastewater.     

Interactions of fluoroquinolone antibacterial agents with aqueous chlorine: reaction kinetics, mechanisms, and transformation pathways

Kinetics, products, and mechanistic aspects of reactions between free available chlorine (HOCl/OCl-), ciprofloxacin (CF), and enrofloxacin (EF) were extensively investigated to elucidate the behavior of fluoroquinolone antibacterial agents during water chlorination processes. Although the molecular structures of these two substrates differ only with respect to degree of N(4) amine alkylation, CF and EF exhibit markedly different HOCl reaction kinetics and transformation pathways. HOCI reacts very rapidly at CF's secondary N(4) amine, forming a chloramine intermediate that spontaneously decays in aqueous solution by concerted piperazine fragmentation. In contrast, HOCl reacts relatively slowly at EF's tertiary N(4) amine, apparently forming a highly reactive chlorammonium intermediate (R3N-(4)Cl+) that can catalytically halogenate EF or other substrates present in solution. Flumequine, a fluoroquinolone that lacks the characteristic piperazine ring, exhibits no apparent reactivity toward HOCI but appears to undergo facile halodecarboxylation in the presence of R3N(4)-Cl+ species derived from EF. Measured reaction kinetics were validated in real water matrixes by modeling CF and EF losses in the presence of free chlorine residuals. Combined chlorine (CC) kinetics were determined under selected conditions to evaluate the potential significance of reactions with chloramines. CF's rapid kinetics in direct reactions with HOCl, and relatively high reactivity toward CC, indicate that secondary amine-containing fluoroquinolones should be readily transformed during chlorination of real waters, whether applied chlorine doses are present as free or combined residuals. However, EF's slower HOCl reaction kinetics, recalcitrance toward CC, and participation in the catalytic halogenation cycle described herein suggest that tertiary amine-containing fluoroquinolones will be comparatively stable during most full-scale water chlorination processes.     

Magnetite core-shell nano-composites with chlorine functionality: preparation by miniemulsion polymerization and characterization

Magnetic composite particles with a magnetic core consisting of superparamagnetic iron oxide and a cover layer of hydrophobic polyvinylbenzylchloride are described. The magnetite was prepared by precipitation starting with mixed iron II and iron III salts and coating of the solid with oleic acid. The coating is conducted via the liquid–liquid phase transfer. Thereby oleic acid adsorbed on the magnetite surface. In a second step the oleic acid treated magnetite was coated with polyvinylbenzylchloride in a miniemulsion polymerization to get a protective layer. The obtained magnetite core-shell nano-composites with chlorine functionality were characterized by different methods: particle size measurement, acid treatment, iron content, morphology and elemental profiles across the composite particles diameter. The test result reveals the binding of the iron oxide inside the composites which can be also recognize in TEM pictures.     

Asymmetric synthesis and biological activity of nor-α-tocopherol, a new vitamin E analogue

The vitamin E analogues (2R,4′R,8′R)‐nor‐α‐tocopherol (94 % de) and (2RS,4′R,8′R)‐nor‐α‐tocopherol have been synthesized from (all R)‐hexahydrofarnesol and phytol, respectively. According to in vitro experiments with murine macrophages nor‐α‐tocopherol is an anti‐inflammatory compound more potent than α‐tocopherol.     

Monomers for Adhesive Polymers, 10‐Synthesis,Radical Photopolymerization and Adhesive Properties of Methacrylates Bearing Phosphonic Acid Groups

Syntheses of eight novel methacrylates bearing phosphonic acid groups were synthesized in three to five steps. The interaction of these monomers with hydroxyapatite was investigated using ¹³C‐NMR spectroscopy. Free radical homopolymerizations were carried out in a mixture ethanol/water (2.5/1, v/v) using 2,2′azo(2‐methylpropionamidine) dihydrochloride as initiator. The copolymerization of these monomers with a mixture HEMA/GDMA (5/3, mol/mol) was investigated by photo‐DSC. Dentin shear bond strength measurements showed that 2‐methacryloyloxy‐3‐(1,1,2,2‐tetrafluoroethoxy)propylphosphonic acid 4b , 2,3‐dimethacryloyloxypropylphosphonic acid 18 and 3‐(methacryloyloxy)‐2,2‐(di[(dihydroxyphosphoryl)methyl])propyl methacrylate 23 are promising candidates for dental adhesives.

     

Single Photon Counting With Synchronously Pumped Dye Laser Excitation

ABSTRACT

This article reviews the advances that have been made in the technique of pulse fluorometry with time-correlated single photon counting detection brought about by the introduction of mode-locked synchronously pumped dye laser excitation. High repetition rates and small pulse width permit high data collection rates and excellent time-resolution. A modern pulse fluorometer which allows efficient measurement of fluorescence decay curves as well as automated measurement of time-resolved fluorescence spectra and of fluorescence anisotropy decays is described in detail.     

Methods for the photometric determination of reactive bromine and chlorine species with ABTS

New methods for the determination of reactive bromine and chlorine species are presented. Hypobromous acid (HOBr) and all three bromamines species (NH₂Br, NHBr₂, NBr₃) are analyzed as a sum parameter and hypochlorous acid (HOCl), monochloramine (NH₂Cl) and chlorine dioxide (ClO₂) can be determined selectively. However, no distinction is possible between HOCl and the active bromine species. The bromine and chlorine species react with ABTS (2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid-diammonium salt) to a green colored product that is measured at 405 or 728 nm. Free chlorine and NH₂Cl can be measured in the presence of ozone. The method is therefore suitable if combinations of disinfectants are used, such as chlorine/chlorine dioxide or chlorine/ozone. In natural waters, the method provides a detection limit for all chlorine/bromine species of less than 0.1 μM. The colored reaction product is very stable and allows a fixation of the chlorine/bromine species in the field and subsequent determination of the absorption in the laboratory.