Temperature dependences of the Peclet number in sublimation processes of simple substances

The results of calculating the Peclet number Ре = wr/(ρD) (where D is the diffusion coefficient; w is the evaporation rate of the substance; ρ is the density of the substance; r is the size factor) in sublimation processes of simple substances with high values of vapor pressure (≈ 1 mm Hg and above at the melting temperature): As, Gd, Tm, Lu, Cr, Yb, Sm, Mg, Ra, Ca, Sr, Ni, Co, Eu, Mn, Ba. It is shown that the nature of the temperature dependence Pe(T) is determined by the properties of the components of the sublimated system “base–impurity” (including the diffusion activation energy Q of impurity). For each substance for given Q and r, the dependence Pe(T) is monotonic. A decrease in the process temperature can improve the purification of a substance from one of several impurities, accompanied by deterioration in the purification from another impurity.Представлено результати обчислень числа Пекле Ре = wr/(ρD) (де D – коефіцієнт дифузії; w – швидкість випаровування речовини; ρ – щільність речовини; r – розмірний фактор) у процесах сублімації простих речовин з високими значеннями тиску пари (≈ 1 мм рт. ст. і вище при температурі плавлення): As, Gd, Tm, Lu, Cr, Yb, Sm, Mg, Ra, Ca, Sr, Ni, Co, Eu, Mn, Ba. Показано, що характер температурної залежності Ре(Т) визначається властивостями компонентів системи «основа–домішка» (включаючи енергію активації дифузії Q домішки). Для кожної речовини при заданих Q і r залежність Ре(Т) монотонна. Зниження температури процесу може покращувати очищення речовини від однієї з кількох домішок, супроводжуючись погіршенням очищення від іншої домішки.Представлены результаты вычислений числа Пекле Ре = wr/(ρD) (где D – коэффициент диффузии; w – скорость испарения вещества; ρ – плотность вещества; r – размерный фактор) в процессах сублимации простых веществ с высокими значениями давления пара (≈ 1 мм рт. ст. и выше при температуре плавления): As, Gd, Tm, Lu, Cr, Yb, Sm, Mg, Ra, Ca, Sr, Ni, Co, Eu, Mn, Ba. Показано, что характер температурной зависимости Ре(Т) определяется свойствами компонентов сублимируемой системы «основа–примесь» (включая энергию активации диффузии Q примеси). Для каждого вещества при заданных Q и r зависимость Ре(T) монотонна. Снижение температуры процесса может улучшать очистку вещества от одной из нескольких примесей, сопровождаясь ухудшением очистки от другой примеси

Bacterial expression and isotope labeling of AIMP1/p43 codosome protein for structural studies by multidimensional NMR spectroscopy

AIMP1/p43 protein is a structural component of multisynthetase complex (codosome) in eukaryotes, which reveals both tRNA binding and cytokine activities. Aim. Bacterial expression and purification of isotopically-labeled recombinant AIMP1/p43 protein in E. coli cells for studying its solution structure by multidimensional NMR spectroscopy. Methods. AIMP1/p43 protein was expressed in E. coli BL21(DE3)pLysE cells on M9 minimal medium with 15N isotope labeling and purified by metal-chelated chromatography. Heteronuclear 2D 1H-15N NMR experiments were performed in solution at 293 K on Agilent DDR2 800 NMR spectrometer. Results. The AIMP1/p43 protein was obtained in uniformly 15N-labeled form as an NMR sample. A high dispersion of resonance signals in the 2D 1H-15N HSQC NMR spectra confirmed the presence of its compact 3D protein structure. The NMR spectrum of AIMP1/p43 demonstrated a high signal-to-noise ratio and sufficient stability to acquire other multidimensional NMR data sets for determination of the structure of AIMP1/p43 protein in solution. Conclusions. The 15N-labeled AIMP1/p43 protein was stable for 4–7 days, which makes possible acquiring the critical NMR experimental data for detailed structural analysis in solution. Our data on the initial NMR spectra indicated the presence of some additional signals in comparison with the NMR spectrum of EMAP II which could be assigned to amino acids of the N-terminal α-helical fragment of AIMP1/p43.AIMP1/p43 – структурний компонент мультисинтетазного комплексу (кодосома) евкаріот, проявляє тРНК зв’язуючу та цитокінову активність. Мета. Провести бактеріальну експресію та очистку ізотопно-міченого рекомбінантнога білка AIMP1/p43 в клітинах E. coli для вивчення його просторової структури методами мультивимірної ЯМР спектроскопії. Методи. AIMP1/p43 був експресованний в клітинах E. coli BL21 (DE3) pLysE на мінімальному середовищі М9 з міченням ізотопом 15N та очищено за допомогою метал-хелатуючої хроматографії. Гетероядерні двомірні 1H-15N ЯМР експерименти проводилися в розчині при температурі 293 К на ЯМР спектрометрі Agilent DDR2 800. Результати. Білок AIMP1/p43 був отриманий в 15N-міченій формі в якості ЯМР зразка. Висока дисперсія сигналів у двомірниї ЯМР спектрах 1H-15N HSQC підтверджує наявність компактної тривимірної структури білка. ЯМР спектр AIMP1/р43 виявляє значне співвідношення сигнал-шум та достатню стабільність, щоб застосувати інші багатовимірні ЯМР експерименти, для визначення структури AIMP1/p43 білка у розчині. Висновки. 15N-мічений білок AIMP1/p43 зберігає стабільність протягом 4–7 днів, що дає можливість подальшого отримання важливих ЯМР експериментів для проведення детального структурного аналізу білка у розчині. Наші дані первинного аналізу даних ЯМР вказують на присутність деяких додаткових сигналів у порівнянні зі спектрами ЯМР EMAP II, які можуть бути віднесені до амінокислот N-кінцевий α-спірального фрагмента AIMP1/р43.Белок AIMP1/p43 является структурным компонентом мультисинтетазного комплекса (кодосома) эукариот, проявляет тРНК связующую и цитокиновую активность. Цель. Провести бактериальную экспрессию и очистку изотопно-меченого рекомбинантного белка AIMP1/p43 в клетках E. coli, для изучения его пространственной структуры методами мультимерной ЯМР спектроскопии. Методы. AIMP1/p43 экспрессировали в клетках E. coli BL21 (DE3) pLysE на минимальной среде М9 с мечением изотопом 15N и очистили с помощью металл-хелатирующий хроматографии. Гетероядерные двухмерные 1H-15N ЯМР эксперименты проводились в растворе при температуре 293 К на ЯМР спектрометре Agilent DDR2 800. Результаты. Белок AIMP1/p43 был получен в 15N-меченой форме в качестве ЯМР образца. Высокая дисперсия сигналов в двумерных ЯМР спектрах 1H-15N HSQC подтверждает наличие компактной трехмерной структуры белка. ЯМР спектр AIMP1/р43 показывает значительное соотношение сигнал-шум и достаточную стабильность, чтобы применить другие многомерные ЯМР эксперименты для определения структуры AIMP1/p43 белка в растворе. Выводы. 15N-меченый белок AIMP1/p43 сохраняет стабильность в течение 4–7 дней, что дает возможность дальнейшего получения важных ЯМР экспериментов для проведения детального структурного анализа белка в растворе. Наши данные первичного анализа данных ЯМР указывают на присутствие некоторых дополнительных сигналов в сравнении со спектрами ЯМР EMAP II, которые могут быть отнесены к аминокислот N-концевой ?-спирального фрагмента AIMP1/р43

Constructions of free commutative integro-differential algebras

In this survey, we outline two recent constructions of free commutative integro-differential algebras. They are based on the construction of free commutative Rota-Baxter algebras by mixable shuffles. The first is by evaluations. The second is by the method of Gr\"obner-Shirshov bases.Comment: arXiv admin note: substantial text overlap with arXiv:1302.004

History effect in inhomogeneous superconductors

A model was proposed to account for a new kind of history effect in the transport measurement of a sample with inhomogeneous flux pinning coupled with flux creep. The inhomogeneity of flux pinning was described in terms of alternating weak pinning (lower jc) and strong pinning region (higher jc). The flux creep was characterized by logarithmic barrier. Based on this model, we numerically observed the same clockwise V-I loops as reported in references. Moreover, we predicted behaviors of the V-I loop at different sweeping rates of applied current dI/dt or magnetic fields Ba, etc. Electric transport measurement was performed in Ag-sheathed Bi2-xPbxSr2Ca2Cu3Oy tapes immersed in liquid nitrogen with and without magnetic fields. V-I loop at certain dI/dt and Ba was observed. It is found that the area of the loop is more sensitive to dI/dt than to Ba, which is in agreement well with our numerical results.Comment: To appear in Phys Rev B, October 1 Issu

Reaction rate for two--neutron capture by 4^4He

Recent investigations suggest that the neutrino--heated hot bubble between the nascent neutron star and the overlying stellar mantle of a type--II supernova may be the site of the r--process. In the preceding $\alpha$--process building up the elements to $A \approx 100$, the $^4$He(2n,$\gamma$)$^6$He-- and $^6$He($\alpha$,n)$^9$Be--reactions bridging the instability gap at $A=5$ and $A=8$ could be of relevance. We suggest a mechanism for $^4$He(2n,$\gamma$)$^6$He and calculate the reaction rate within the $\alpha$+n+n approach. The value obtained is about a factor 1.6 smaller than the one obtained recently in the simpler direct--capture model, but is at least three order of magnitude enhanced compared to the previously adopted value. Our calculation confirms the result of the direct--capture calculation that under representative conditions in the $\alpha$--process the reaction path proceeding through $^6$He is negligible compared to $^4$He($\alpha$n,$\gamma$)$^9$Be.Comment: 13 pages, 4 postscript figures, to appear in "Zeitschrift f. Physik A", changed internet address and filename, the uuencoded postscript file including the figures is available at ftp://is1.kph.tuwien.ac.at/pub/ohu/twoneutron.u

Magnetic field - temperature phase diagram of quasi-two-dimensional organic superconductor lambda-(BETS)_2 GaCl_4 studied via thermal conductivity

The thermal conductivity kappa of the quasi-two-dimensional (Q2D) organic superconductor lambda-(BETS)_2 GaCl_4 was studied in the magnetic field H applied parallel to the Q2D plane. The phase diagram determined from this bulk measurement shows notable dependence on the sample quality. In dirty samples the upper critical field H_{c2} is consistent with the Pauli paramagnetic limiting, and a sharp change is observed in kappa(H) at H_{c2 parallel}. In contrast in clean samples H_{c2}(T) shows no saturation towards low temperatures and the feature in kappa(H) is replaced by two slope changes reminiscent of second-order transitions. The peculiarity was observed below ~ 0.33T_c and disappeared on field inclination to the plane when the orbital suppression of superconductivity became dominant. This behavior is consistent with the formation of a superconducting state with spatially modulated order parameter in clean samples.Comment: 10 pages, 8 figures, new figure (Fig.5) and references added, title change

Effect of electron irradiation on vortex dynamics in YBa_2Cu_3O_{7-x} single crystals

We report on drastic change of vortex dynamics with increase of quenched disorder: for rather weak disorder we found a single vortex creep regime, which we attribute to a Bragg-glass phase, while for enhanced disorder we found an increase of both the depinning current and activation energy with magnetic field, which we attribute to entangled vortex phase. We also found that introduction of additional defects always increases the depinning current, but it increases activation energy only for elastic vortex creep, while it decreases activation energy for plastic vortex creep.Comment: 4 pages, 3 figures, submited to Phys. Rev.

Hysteretic behavior of the vortex lattice at the onset of the second peak for HgBa2_2CuO4+δ_{4+\delta} superconductor

By means of local Hall probe ac and dc permeability measurements we investigated the phase diagram of vortex matter for the HgBa$_2$CuO$_{4+\delta }$ superconductor in the regime near the critical temperature. The second peak line, $H_{\rm sp}$, in contrast to what is usually assumed, doesn't terminate at the critical temperature. Our local ac permeability measurements revealed pronounced hysteretic behavior and thermomagnetic history effects near the onset of the second peak, giving evidence for a phase transition of vortex matter from an ordered qausilattice state to a disordered glass

Technical design and performance of the NEMO3 detector

The development of the NEMO3 detector, which is now running in the Frejus Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun more than ten years ago. The NEMO3 detector uses a tracking-calorimeter technique in order to investigate double beta decay processes for several isotopes. The technical description of the detector is followed by the presentation of its performance.Comment: Preprint submitted to Nucl. Instrum. Methods A Corresponding author: Corinne Augier ([email protected]

The performance of the jet trigger for the ATLAS detector during 2011 data taking

The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction