Ion-induced nucleation of dibutyl phthalate vapors on spherical and nonspherical singly and multiply charged polyethylene glycol ions

Dibutyl phthalate vapor nucleation induced by positive polyethylene glycol (PEG) ions with controlled sizes and charges was experimentally studied. The ions were produced by electrospray ionization, classified in a high-resolution differential mobility analyzer, and studied in a nano condensation nucleus counter of the mixing type. Ionic radii of PEG varied from 0.52 to 1.56 nm, including from singly to quadruply charged ions. Some of these ions are fully stretched chains, other are spherical, and others have intermediate forms, all of them having been previously characterized by mobility and mass spectrometry studies. Activation of PEG1080(+2) requires a supersaturation almost as high as that required for small singly charged ions and higher than for PEG1080(+). This anomaly is explained by the Coulombic stretching of the ion into a long chain, where the two charged centers appear to be relatively decoupled from each other. The critical supersaturation for singly charged spherical ions falls below Thomson's (capillary) theory and even below the already low values seen previously for tetraheptyl ammonium bromide clusters. Spherical PEG4120(+2) falls close to the Thomson curve. The trends observed for slightly nonspherical PEG4120(+3) and highly nonspherical (but not quite linear) PEG4120(+4) are intermediate between those of multiply charged spheres and small singly charged ions.     

Phenomenological J-plane singularities of amplitudes at T = 0

The Mellin transforms of the imaginary parts of the πN forward amplitudes are computed from the experimental total cross sections. An analytic continuation of these transforms is performed to determine the phenomenological J-plane singularities at t = 0. The continuation supports the J-plane analyticity assumption in the case I = 0. A generalization of the method to non-forward t-values is indicated. The effective Regge cut is found to be small in I = 1 amplitudes.     

Design and analysis of a feedback time difference amplifier with linear and programmable gain

This paper proposes a feedback time difference amplifier (FTDA) that achieves linear, controllable gain and changeable input range for different time difference gains. The proposed FTDA consists of two identical feedback output generators. The feedback output generator achieves a linear input–output transfer characteristic by employing two p-type keepers for time gain feedback control. Its validity was demonstrated using \({0.13}\, {\upmu \hbox {m}}\) SiGe BiCMOS process. The power consumption is \(91.54 \,{\upmu \hbox {W}}\) for the highest gain with input signals at \({2}\,\hbox {MHz}\). The gain can be controlled from 25.06 to \(734.9\,{\hbox {s/s}}\) within \(40 \,\hbox {ps}\) input time interval.     

Reductive coprecipitation as a separation method for the determination of gold,palladium, platinum,rhodium, silver,selenium and tellurium in geological samples by graphite furnace atomic absorption spectrometry

A method for the separation of Au, Pd, Pt, Rh, Ag, Te and Se from geological samples at trace levels is presented. The elements are separated from the matrix after dissolution by reductive coprecipitation using mercury as a collector and tin(II) chloride as a reductant. The efficiency of coprecipitation is studied by varying the acidity of the solutions and the amount of collector. The analyte elements are determined by graphite furnace atomic absorption spectrometry. In the determination of volatile elements (Te, Au and Ag), matrix modification with iridium is used. Selenium is determined with a mixed matrix modifier containing ascorbic acid and iridium. The method is tested by analysing geochemical reference samples.     

A Cheap One-Pot Approach to Tetraethyl Methylenediphosphonate

A cheap procedure for the preparation of tetraethyl methylene-diphosphonate is described.     

Combined synthesis and in situ coating of nanoparticles in the gas phase

Ga₂O₃ was-synthesized by doping a premixed H₂/O₂/Ar flat flame with diluted trimethyl gallium Ga(CH₃)₃ in a low-pressure reactor. The mean particle diameter d _p of the resulting metal oxide was characterized in-situ with a particle mass spectrometer (PMS), and was observed to range between 2.5 nm ≤ d _p ≤ 6.5 nm. XRD results show that the as-synthesized Ga₂O₃ nanoparticles are mostly amorphous, although, a few broad reflexes were observed that indicate the presence of some degree of crystallinity. Thermal annealing of the as-synthesized material at 1000 °C for 5 min yielded β-Ga₂O₃ with a monoclinic structure. UV–VIS measurements indicate strong absorption in the UV range (4.8 eV), which corresponds quite well to the direct band gap of bulk Ga₂O₃. Photoluminescence (PL) measurements of the as-synthesized metal oxide show a broad emission ranging from 350 nm to 600 nm with a maximum at 460 nm. Crystalline β-Ga₂O₃ exhibited stronger luminescence than as-synthesized particles.     

Synthesis of copolymer-stabilized silver nanoparticles for coating materials

Silver ions being less toxic than silver nanoparticles, a more safe material can be obtained to be used as antimicrobial coating. This can be achieved by using thiol chemistry and covalently attach the silver nanoparticles in the coating. Our aim is to produce a coating having antimicrobial properties of silver ions but with the silver nanoparticles firmly attached in the coating. Here, we present a way to produce silver nanoparticles that can be used as a component in a coating or as such to produce an antimicrobial coating. The silver nanoparticles presented here are stabilized by a copolymer (poly(butyl acrylate–methyl methacrylate)) that is soft and has well-known good film-producing properties. The reversible addition-fragmentation chain transfer radical polymerization technique used to prepare the polymers provides conveniently a thiol group for effective binding of the silver nanoparticles to the polymers and thus to the coating.