Non-perturbative vacuum-polarization effects in proton-laser collisions

In the collision of a high-energy proton beam and a strong laser field, merging of the laser photons can occur due to the polarization of vacuum. The probability of photon merging is calculated by accounting exactly for the laser field and presents a highly non-perturbative dependence on the laser intensity and frequency. It is shown that the non-perturbative vacuum-polarization effects can be experimentally measured by combining the next-generation of table-top petawatt lasers with presently available proton accelerators.Comment: 5 pages, 2 figure

Особенности изготовления отливок из алюминиевых сплавов по выжигаемым аддитивным FDM-моделям

This article describes the results of a study aimed at improving production technology of experimental castings from aluminum alloys by investment casting using models produced by 3D printing. The consumable models were produced using fused deposition modeling (FDM). Biodegradable polylactide (PLA) was used as a material for the models. In order to decrease the surface roughness of consumable PLA  model.  chemical  post-treatment  by  dichloromethane  needs  to  be  performed.  After  immersion  of  the  model  into the solvent for 10s, its surface becomes smooth and glossy. Three-point static bending tests of PLA plates demonstrated a mechanical strength of average ~45.1 MPa. A thermomechanical analysis of polylactide demonstrated that in the course of heating of ceramic shell in excess of 150 °C, the polylactide model begins to expand intensively by exerting significant pressure on the ceramic shell. In order to decrease stress during the removal of polylactide model from ceramic mold, the heating time in the range of 150–300 °C needs to be heated to a maximum. The use of hollow consumable casting models with a cellular structure not higher than 30 % is also sensible. The stresses on the shell will not exceed its strength. Characteristic  temperature  properties  of  PLA  plastic  thermal  destruction  were detected using thermogravimetric analysis. Polylactide was established to completely burn out upon  heating  to 500  °C  leaving  no ash residue. Analysis of the results identified the burning modes of polylactide models from ceramic molds. Using a Picaso 3D Designer printer (Russia), the PLA models were printed used for production of experimental castings from aluminum alloys. It was revealed that the surface roughness (Ra) of a casting produced using a consumable model treated by dichloromethane decreases by 81.75 %: from 13.7 to 2.5 μm.Приведены результаты исследований, направленные на совершенствование литейной технологии получения опытно-экспериментальных отливок из алюминиевых сплавов методом литья по выжигаемым моделям, изготовленным с применением 3D-печати. Для создания выжигаемых моделей использовали метод осаждения расплавленной нити (FDM – fused deposition modeling), а в качестве материала моделей был выбран биоразлагаемый материал – полилактид (PLA – polylactide). Установлено, что для уменьшения  шероховатости  выжигаемой  PLA-модели  необходимо  проводить  химическую  постобработку ее поверхности дихлорметаном. В результате окунания модели в растворитель на 10 с она приобретает гладкую и глянцевую поверхность. Испытания механической прочности PLA-пластин на трехточечный статический изгиб показали, что данный показатель составляет в среднем ~ 45,1 МПа. Термомеханический анализ полилактида выявил, что в процессе нагрева керамической оболочки выше 150 °С полилактидная модель начинает интенсивно расширяться, оказывая существенное давление на керамическую оболочку. Для уменьшения напряжений в процессе удаления полилактидной модели из керамической формы необходимо максимально увеличить время нагрева в интервале температур 150–300 °С, а также целесообразно использовать пустотелые выжигаемые модели отливки со степенью заполнения ячеистой структуры не более 30 %. При этом напряжения в оболочке не будут превышать ее прочность. С помощью термогравиметрического анализа выявлены характерные температурные характеристики термодеструкции PLA-пластика. Установлено, что материал из полилактида полностью  выгорает  при нагреве до температуры 500 °С, не оставляя после себя остатков золы. Анализ результатов позволил определить технологические режимы выжигания полилактидных моделей из керамических форм. На принтере Picaso 3D Designer (Россия) были напечатаны PLA-модели, которые  использовали  для  получения  опытно-экспериментальных  отливок  из  алюминиевых  сплавов.  Выявлено, что шероховатость поверхности (Ra)  отливки,  полученной  по  выжигаемой  модели,  обработанной  дихлорметаном,  уменьшается на 81,75 % – с 13,7 до 2,5 мкм

Thermochemistry of dissolution, solvation, and hydrogen bonding of anilines in proton-acceptor organic solvents at 298.15 K

© 2014 Pleiades Publishing, Ltd. Enthalpies of dissolution at infinite dilution (298.15 K) of aniline, N-methylaniline, and N,N-dimethylaniline in a series of proton-acceptor solvents of different classes of compounds have been measured. The solvation enthalpies have been determined, and its relationship with the anilines structure has been analyzed. Enthalpy of hydrogen bonding in the complexes of aniline (1: 2) and N-methylaniline (1: 1) with the solvents has been calculated. In the case of aniline complexes, negative cooperativity of hydrogen bonding has been revealed, the effect enhancing with increasing the solvent proton-acceptor ability

Thermodynamics of the hydrogen bonding of nitrogen-containing cyclic and aromatic compounds with proton donors: The structure-property relationship

© 2014 Pleiades Publishing, Ltd. Enthalpies of dissolution are measured at infinite dilution of nitrogen-containing cyclic (pyrrolidine, piperidine) and aromatic compounds (aniline, N-methylaniline, N,N-dimethylaniline, N-methylimidazole, pyridine, 2-, 3-, 4-methylpyridine, pyrrole, N-methylpyrrole) in chloroform and dichloromethane, and vice versa (T = 298.15 K). The enthalpies of hydrogen bonds in the above systems are calculated. Relationships between resulting thermochemical data and the structure of nitrogen-containing cyclic and aromatic compounds are explored

The ability of ionic liquids to form hydrogen bonds with organic solutes evaluated by different experimental techniques. Part I. Alkyl substituted imidazolium and sulfonium based ionic liquids

© 2018 This work is devoted to the quantitative study of hydrogen bond formation of N-alkyl substituted ionic liquids with proton acceptor and proton donor organic solvents. 1-Butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [BMIM][NTf2], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], triethylsulfonium bis(trifluoromethylsulfonyl)imide [Et3S][NTf2], 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM], 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM][BF4] were investigated by solution calorimetry and FTIR-spectroscopy techniques. The stretching vibration region of C[dbnd]O group of 2-pentanone in mixture with N-alkyl substituted ionic liquid in inert solvent carbon tetrachloride was analyzed at different concentrations of components for the estimation of proton donor ability of ionic liquids. Also, the stretching vibration region of the OH-group of methanol was studied in a ternary system carbon tetrachloride (inert solvent), methanol (proton donor) and N-alkyl substituted ionic liquid for the estimation of proton acceptor ability of ionic liquids. The hydrogen bond enthalpy of methanol in ionic liquids was calculated using data of measured solution enthalpies and data extracted from the literature. The frequency shifts of the OH-group of methanol induced by intermolecular interactions within ionic liquids in a carbon tetrachloride solution were compared with the hydrogen bonding enthalpies of methanol with ionic liquids. A linear relationship between the frequency shifts of the OH-groups and hydrogen binding enthalpies of methanol in ionic liquids were found. According to measured FTIR-spectroscopy data, the N-alkyl substituted ionic liquids analyzed in this work possess weak proton donor properties, and at the same time their proton acceptor ability (basicity) is much higher and shows dependency on anion structure

Development of an effective scale inhibitor based on organophosphonic compounds in an aqueous-alcohol solvent

© 2015 Springer Science+Business Media New York. We have studied the effect of the ratio of hydroxyethylidene diphosphonic acid and nitrilotri(methylphosphonic acid) and also polyaminopolyether methylenephosphonate chelating agent additives on scale inhibition in simulated formation water. We show that replacing the water with an aqueous-alcohol solvent lowers considerably the pour point of the reagent without having an appreciable effect on its effectiveness. We have developed a composition that exhibits high effectiveness of scale inhibition for scale composed of calcium carbonate and also calcium and barium sulfates when added at 10-20 mg/L

Synthesis of fully bio-based and solvent free non-isocyanate poly (ester amide/urethane) networks with improved thermal stability on the basis of vegetable oils

© 2018 Elsevier Ltd The purpose of this study is to synthesize non-isocyanate poly (ester amide/urethane) networks, based entirely on vegetable oil through a green method, i.e., without solvent and having any rigid and aromatic structures to improve their thermal stability. For this purpose, first, three amines were synthesized from castor oil and oleic acid. Second, carbonated sunflower oil (CSFO) was obtained by reaction of epoxidized sunflower oil with CO2 at atmospheric pressure. In the final step, CSFO easily reacted with bio-based amines by melt-blending without catalyst to give corresponding non-isocyanate polyurethane (NIPU) networks. The Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) techniques were applied to characterize the structural, thermal and physical features of NIPU networks. In addition, to determine the environmental stability the water absorption amount and the degradation percentage were calculated in the deionized water and phosphate saline buffer, respectively. These NIPU networks showed an excellent thermal stability (T5 wt% between 323 and 386 °C), low water absorption and degradation (4–10 and 1.04–1.40 wt% respectively). The results show the potential of this environmentally friendly strategy for preparing bio-based NIPU for high performances. Furthermore, the presence of an aliphatic ester group and their biodegradability nature may also make them proper for biological and/or biomedical applications

Thermochemistry of hydrogen bonding of proton acceptors in the media of linear and cyclic amides. Cooperativity effects in multi-particle complexes of amides

© 2017 Elsevier B.V. In present work a thermochemistry of hydrogen bond formation of proton acceptors (B) in the medium of linear (N-methylformamide (NMF)) and cyclic (2-pyrrolidone (Py)) amides was studied. The infinite dilution solution enthalpies of nitriles, ketones, esters, ethers and amines in amides were measured at 298.15 K. Enthalpies of hydrogen bonding of proton acceptors in solution linear and cyclic amides were calculated and compared with previously determined the enthalpies of hydrogen bonding of amides in proton acceptor media. The cooperative effects of hydrogen bonding in multi-particle complexes of amides with proton acceptors were evaluated. It was shown that cooperativity coefficients were decreased with increasing the basicity of proton acceptors

Thermochemistry of hydrogen bonding of linear and cyclic amides in proton acceptors media

© 2017 Elsevier B.V.In present work thermochemistry of hydrogen bond formation of linear (acetamide (АА), N-methylacetamide (NMA), N,N-dimethylacetamide (DMAA)) and cyclic amides (2-pyrrolidone (Py), N-methyl-2-pyrrolidone (MPY)) in the medium of proton acceptors (B) was studied. Enthalpies of solution of amides in nitriles, ketones, esters, ethers and amines were measured at 298.15 and infinite dilution conditions. Enthalpies of hydrogen bonding of studied solutes with proton acceptor solvents were determined on the basis of experimental data. It was shown that proton donor properties of 2-pyrrolidone are more pronounced than linear amides. Enthalpies of hydrogen bonding of acetamide in proton acceptors are twice more than N-methylacetamide due to formation of 1:2 complexes

Thermodynamic of dissolution and hydrogen bond of the pyrrole, N-methylpyrrole with proton acceptors

© 2016 Elsevier B.V.Enthalpies of dissolution of pyrrole, N-methylpyrrole in proton acceptor solvents and proton acceptors in the medium of pyrrole, N-methylpyrrole were measured. The enthalpies of hydrogen bond of pyrrole, N-methylpyrrole with proton acceptors were calculated from experimental data of solution enthalpy of amines with organic compounds. The hydrogen bond enthalpies of proton acceptors with N- methylpyrrole are equal to zero unlike with pyrrole. The hydrogen bond enthalpies of proton acceptors (B) in pyrrole are significantly lower than the enthalpies of hydrogen bonding of systems of pyrrole-base in the complexes 1:1 due to reorganization effects of pyrrole as solvent. The cooperative effects in multi-particle complexes of pyrrole with bases are negligible