Elastic properties of FeSi

Measurements of the sound velocities in a single crystal of FeSi were performed in the temperature range 4-300 K. Elastic constants $C_{12}$ and $C_{44}$ deviate from a quasiharmonic behavior at high temperature; whereas, $C_{12}$ increases anomalously in the entire range of temperature, indicating a change in the electron structure of this materia

Ultrasonic studies of the magnetic phase transition in MnSi

Measurements of the sound velocities in a single crystal of MnSi were performed in the temperature range 4-150 K. Elastic constants, controlling propagation of longitudinal waves reveal significant softening at a temperature of about 29.6 K and small discontinuities at $\sim$28.8 K, which corresponds to the magnetic phase transition in MnSi. In contrast the shear elastic moduli do not show any softening at all, reacting only to the small volume deformation caused by the magneto-volume effect. The current ultrasonic study exposes an important fact that the magnetic phase transition in MnSi, occurring at 28.8 K, is just a minor feature of the global transformation marked by the rounded maxima or minima of heat capacity, thermal expansion coefficient, sound velocities and absorption, and the temperature derivative of resistivity.Comment: 4 pages, 4 figure

Particle deposition in a realistic geometry of the human conducting airways: Effects of inlet velocity profile, inhalation flowrate and electrostatic charge:Effects of inlet velocity profile, inhalation flowrate and electrostatic charge

AbstractUnderstanding the multitude of factors that control pulmonary deposition is important in assessing the therapeutic or toxic effects of inhaled particles. The use of increasingly sophisticated in silico models has improved our overall understanding, but model realism remains elusive. In this work, we use Large Eddy Simulations (LES) to investigate the deposition of inhaled aerosol particles with diameters of dp=0.1,0.5,1,2.5,5 and 10μm (particle density of 1200kg/m3). We use a reconstructed geometry of the human airways obtained via computed tomography and assess the effects of inlet flow conditions, particle size, electrostatic charge, and flowrate. While most computer simulations assume a uniform velocity at the mouth inlet, we found that using a more realistic inlet profile based on Laser Doppler Anemometry measurements resulted in enhanced deposition, mostly on the tongue. Nevertheless, flow field differences due to the inlet conditions are largely smoothed out just a short distance downstream of the mouth inlet as a result of the complex geometry. Increasing the inhalation flowrate from sedentary to activity conditions left the mean flowfield structures largely unaffected. Nevertheless, at the higher flowrates turbulent intensities persisted further downstream in the main bronchi. For dp>2.5μm, the overall Deposition Fractions (DF) increased with flowrate due to greater inertial impaction in the oropharynx. Below dp=1.0μm, the DF was largely independent of particle size; it also increased with flowrate, but remained significantly lower. Electrostatic charge increased the overall DF of smaller particles by as much as sevenfold, with most of the increase located in the mouth–throat. Moreover, significant enhancement in deposition was found in the left and right lung sub-regions of our reconstructed geometry. Although there was a relatively small impact of inhalation flowrate on the deposition of charged particles for sizes dp<2.5μm, impaction prevailed over electrostatic deposition for larger particles as the flowrate was increased. Overall, we report a significant interplay between particle size, electrostatic charge, and flowrate. Our results suggest that in silico models should be customized for specific applications, ensuring all relevant physical effects are accounted for in a self-consistent fashion

Interplay between lattice, orbital, and magnetic degrees of freedom in the chain-polymer Cu(II) breathing crystals

The chain-polymer Cu(II) breathing crystals C21H19CuF12N4O6 were studied using the x-ray diffraction and ab initio band structure calculations. We show that the crystal structure modification at T=146 K, associated with the spin crossover transition, induces the changes of the orbital order in half of the Cu sites. This in turn results in the switch of the magnetic interaction sign in accordance with the Goodenough-Kanamori-Andersen theory of the coupling between the orbital and spin degrees of freedom.Comment: 6 pages, 7 figure

Ecological Assessment of differrent raw materials for biogas

ABSTRACT: A comparative ecologic valuation of different raw materials for biogas production has been made. The valuation is based on the qualities of the different substrates: from energy cultures (sugar, fodder and red beet, leaves mass from the Paulovnia spring and autumn leaves). Three type of fertilizer (cattle from non-litter breeding, swine and non-removable bird fertilizer litter) as well as substrates from waste water of the WTP- Waster water treatment plan (mixed sediment, primary and secondary sediment). The examined raw material has been analyzed according to the following parameters: Dry matter (DM), Organic matter (OM), Organic Carbon (OC), Nitrogen Kjeldahl (N), Nitrogen Ammonium (N - ammonium), Nitrogen nitrate ( N- nitrate), Patassium (K), P (Phosphorus), pH ( H2O) and heavy metals – arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pd), Zinc (Zn). The results of the examined substrates received from different raw materials (vegetal, organic fertilizers and waste water) give us ground to make the following conclusions: the examined substrates respond in the physical-chemical parameters to all technological requirements of raw material for biogas production (DM,C and proportion C:N). The established differences in the content of nitrogen / within the borders of 1,8% (substrate-leaves mass Paulovnia- spring) to 7,75% of substrate 7 (organic fertilizer)/ allow the combination of the substrates in order to adhere the Nitrate directive of the EU. The established differences in the active forms of nitrogen allow exploitation of programs for fertilizers with the participation of raw materials for biogas production. Our examination of substrates and show a content of heavy elements under the critical admissible limits. РЕЗЮМЕ: Направена е сравнителна екологична оценка на различни суровини за производство на биогаз. Оценката е на база качествата на различни субстрати: от енергийни култури (захарно, кръмно и червено цвекло, листна маса от Пауловния- пролетни и есенни листа, царевичен силаж и силаж Пауловния), три вида тор (говежда от безпостелно отглеждане, свинска и несменяема птича торова постеля), както и субстрати от отпадни води на ПС (първична,вторична и смесена утайка). Изследваните суровини бяха анализирани по следните показатели: Dry matter (DM) ,Organic matter (OM), Organic Carbon (OC), Nitrogen Kjeldahl (N), Nitrogen Ammonium (N -ammonium), Nitrogen nitrate (N- nitrate), Patassium (K), P (Phosphorus), pH ( H2O) and heavy metals – arsenic (As), Cadmium (Cd), Chromium ( Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pd), Zinc (Zn). Резултатите от изследваните субстрати получени от различни суровини ( растителни, органични торове и отпадни води) ни дават основание да направим следните заключения: Изследваните субстрати по физикохимични показатели отговарят на всички технологични изисквания на суровини за производство на биогаз (СВ, С и съотношение С:N). Установените различия в съдържанието на азот е границите на 1,8% (субсрат - листна маса Пауловния –пролет) до 7,75% (при субстрат 7 - органична тор) позволяват комбиниране на субстратите с оглед спазване на Нитратната директива на ЕС. Съществуващите различия в подвижните форми на азота дават възможност за разработване на програми за торете с участие на различни суровини за производство на биогаз. Проучените от нас субстрати показват съдържание на тежки елементи под критично допустимите граници

Electrical discharges in the atmosphere of Venus

Data received from Venera 11 and 12 experiments involving the electrical activity of the atmosphere of Venus show that the electrical discharges occur in the cloud layer. Their energy is roughly the same as in terrestrial lightning, but with a pulse repetition frequency of the discharges which is much greater

Study of application of hydrophobic fibrous sorbents for water purification from metal ions

Sorption properties of hydrophobic fibrous sorbents on the basis of polypropylene and polyethylene terephthalate produced from thermoplastic polymer wastes to metal ion series in aqueous media has been studied. Based on the experimental data of extraction degree dependencies on fibre laying density, dispersity, presence of air in sorbent, volume of pass solution the mechanism of metal ion sorption from aqueous media with hydrophobic fibrous materials is suggested

New method for preparation of delivery systems of poorly soluble drugs on the basis of functionalized mesoporous MCM-41 nanoparticles

MCM-41 silica with spherical morphology and small particle sizes (100 nm) was synthesized and modified by post-synthesis method with amino and/or carboxylic groups. Solid state reaction was applied for the first time for loading of poorly soluble drug mesalazine (5-aminosalicylic acid – 5-ASA). Thenon-loaded and drug loaded mesoporous silicas were characterized by XRD, TEM, N2 physisorption, elemental analysis, thermal analysis, FT-IR and solid state NMR spectroscopy. Quantum-chemical calculations were used to predict the interactions between the drug molecule and the functional groups of the carrier. The nanoparticles were post-coated with sodium alginate and the coating modified the rate of mesalazine release from MCM-41NH2 and MCM-41NH2COOH particles. Cytotoxic evaluation on colon adenocarcinoma cell line revealed that the alginate coating reduced cytotoxicity of mesalazine loaded in the post-coated particles compared to the pure mesalazine. The functionalized, polymer coated mesoporous systems are suitable oral drug delivery systems providing an opportunity to modify drug release