Effect of amino and polysiloxane groups on the chemical adsorption of polymers containing thiophosphate at the oil/metal interface under extreme pressure

Copolymers that separately contained thiophosphate–polysiloxane, thiophosphate–amino, and thiophosphate–polysiloxane–amino groups were synthesized and characterized. The performances of these synthesized copolymers on metal surfaces under a high load and rotary velocity were examined by the measurement of the oil temperature, frictional coefficient, and electrical contact resistance between two metal surfaces. The configuration of the adsorption layer was studied with energy‐dispersive spectrometry (EDS) and scanning electron microscopy (SEM). Copolymers that contained amino–thiophosphate groups reduced the frictional coefficient between two metal surfaces and markedly limit the increase in the oil temperature. Notably, a higher content of polysiloxane groups in the copolymer corresponded to an increased operating time to establish the adsorption layer on the metal surface. However, a higher content of amino groups reduced the time required for the layer to form. The adsorption layers that formed on the metal surfaces were investigated by EDS as phosphides produced by a chemical reaction of the thiophosphate‐containing copolymer with the metal surface. These adsorption layers on the metal surface were directly observed with SEM. The layer that formed on the metal surface of copolymers containing less polysiloxane and more amino groups was the thickest layer for all the synthesized copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1795–1803, 2002     

Double prompt photon production at high transverse momentum byπ − on protons at 280 GeV/c

A search for pairs of highp _T prompt photons produced in hydrogen by a 280 GeV/c incidentπ ^- beam has been carried out using a fine-grained electromagnetic calorimeter and the Omega spectrometer at the CERN SPS. Clear evidence for the existence of such events is found with a six standard deviation signal forp _T >3.0 GeV/c. The cross-sections are consistent with beyond leading order QCD calculations. A discussion on the determination of α _s is also presented.     

The structure of events triggered by direct photons in π− p, π+ p andpp collisions at 280 GeV/c

The structure of events associated with the production of direct photons in π^? p, π⁺ p andpp reactions of 280 GeV/c has been studied using data from the WA 70 experiment at the CERN SPS. Results are presented on the distributions of the fractional momenta of the colliding partons and on the fragmentation of the recoil jet and a comparison is made with predictions using the structure functions of Duke and Owens in the Lund Monte Carlo with string fragmentation.     

Isomer-specific influences on ignition and intermediates of two C5 ketones in an RCM

Ketones have been considered as potential biofuels and main components of blend stock for internal engines. To better understand the chemical kinetics of ketones, ignition delay times of 2-pentanone (propyl methyl ketone, PMK) and 3-pentanone (diethyl ketone, DEK) were measured at temperatures of 895–1128 K under 10 and 20 bar, at equivalence ratios (?) of 0.5 and 1.0 in a rapid compression machine (RCM). To explore the impact of carbonyl functionality and resonance stabilized structures of fuel radicals on their combustion kinetics, high-temperature pyrolysis at 1130 K and relatively low-temperature oxidation at 950 K studies were performed in an RCM, and the time-resolved species concentration profiles under these two conditions were quantified using a fast sampling system and gas chromatography (GC). A new kinetic model containing low-temperature reactions was built aiming at predicting the pyrolysis and oxidation behaviors of both ketones. The consumption pathways of the resonance stabilization fuel radicals through oxygen addition and following reactions are promoted since the decomposition rates of these radicals are about 4 orders magnitudes lower than regular fuel radicals. The occurrences of the so-called “addition-dissociation reactions”, i.e., ketones reacting with a hydrogen yielding aldehyde or reacting with a methyl radical yielding shorter-chain-length ketones, are verified in pyrolysis experiments. Based on experiments and model analysis, the carbonyl functionality in both ketones is preserved during the process of β-scissions of fuel radicals and α-scissions of fuel-related acyl radicals, resulting in the direct formation of CO and ketene. However, the position of carbonyl functionality has a significant impact on the species pools.     

Influence of the Oxide Content in the Catalytic Power of Raney Nickel in Hydrogen Generation

The influence of oxides in the hydrogen evolution on Raney nickel electrocatalysts was characterized by electrochemical impedance measurements. In addition, these materials show competitive overpotentials for hydrogen evolution with a modified Watts bath as a binder for the Raney nickel. The optimum result was ?190?mV of overpotential at 100?mA?cm^?2. Oxygen in the Raney Ni catalyst affects its electroactivity toward hydrogen evolution. The source of oxygen is related to the presence of chloride ions in the modified Watts bath. A Watts bath binds Raney Ni particles to the surface of the catalysts and chloride regulates the oxygen content in the nickel binder during electrodeposition. High oxygen content increases the hydrogen evolution overpotential of the electrode. The electroactivity of the synthesized porous coatings was evaluated by polarization curves and impedance plots. In addition, surface characterization by X-ray diffraction, field emission–scanning electron microscopy equipped with energy-dispersive analysis, and X-ray photoelectron spectroscopy is reported.     

Copper ferrite superparamagnetic nanoparticles as a heterogeneous catalyst for directed phenol/formamide coupling

The copper ferrite-catalyzed, directed coupling of ortho-arylated phenols and dialkylformamides in the presence of a peroxide oxidant is described. Acyclic and cyclic amides were compatible with the reaction conditions. The copper ferrite catalyst is heterogeneous since substantial leaching was not detected and re-use of the catalyst for 9 consecutive reactions proceeded without a significant decrease in yield. To the best of our knowledge, this transformation has not been previously performed under heterogeneous catalysis conditions.     

Simultaneous determination of sulfoxaflor and its metabolites,X11719474 and X11721061, in brown rice and rice straw after field application using LC-MS/MS

The present study was carried out to develop an analytical method for simultaneously detecting and quantifying sulfoxaflor and its metabolites (X11721061, X11719474) in brown rice and rice straw using liquid chromatography–tandem mass spectrometry. The parent compound and its metabolites were extracted and purified using original ‘QuEChERS’ method with modification. The matrix-matched calibration curve of sulfoxaflor and its metabolites in both matrices achieved good linearity with determination coefficients (R²) ≥0.9944. The overall recoveries of sulfoxaflor at two fortification levels (rice: 0.2 and 1.0 mg/kg; rice straw: 0.4 and 2.0 mg/kg) ranged from 97.37% to 107.71% with relative standard deviations (RSDs) <5%. On the other hand, the recoveries of both metabolites (X11721061 and X11719474) at 0.1 and 0.5 mg/kg (rice) and 0.2 and 1.0 mg/kg (rice straw) were satisfactory with values ranging from 83.70 % to 112.60% with RSDs <8%. During storage at ?20°C, the analyte and its metabolites were stable for up to 87 days. The limits of quantification of 0.02 mg/kg were lower than the maximum residue limit (0.2 mg/kg) set by the Korean Ministry of Food and Drug Safety for brown rice. The method was successfully applied to paddy field treated with different programme schedules and a preharvest interval of 7 days was proposed based upon the current study. In sum, the developed method is accurate and reproducible for ensuring the reliable determination of sulfoxaflor (and its metabolites) in harvested rice grain and straw samples from the field. The residual level of parent compound does not seem to pose any hazardous effect and treated rice could be safely used for consumption.