Soil water retention curve of agrogray soils: influence of anisotropy and the scaling factor

The soil water characteristic or soil water retention curve (WRC) of medium-loamy gray forest soil horizons was studied in cylinder-shaped samples of disturbed and undisturbed structure. The sample height varied within 2-4 cm and the diameter within 4.5-10 cm. The soil monoliths were sampled in three profiles: vertically, along the slope, and across the slope in accordance with the intrasoil paleorelief formed by the fun-nel-shaped surface of the second humus horizon. The experimental WRC were approximated with the van Genuchten equatio

Electronic structure and possible pseudogap behavior in iron based superconductors

Starting from the simplified analytic model of electronic spectrum of iron - pnictogen (chalcogen) high - temperature superconductors close to the Fermi level, we discuss the influence of antiferromagneting (AFM)scattering both for stoichiometric case and the region of possible short - range order AFM fluctuations in doped compounds. Qualitative picture of the evolution of electronic spectrum and Fermi surfaces (FS) for different dopings is presented, with the aim of comparison with existing and future ARPES experiments. Both electron and hole dopings are considered and possible pseudogap behavior connected with partial FS "destruction" is demonstrated, explaining some recent experiments.Comment: 5 pages, 4 figures, published versio

Possible high temperature superconductivity in Ti-doped A-Sc-Fe-As-O (A= Ca, Sr) system

We report a systematic study on the effect of partial substitution of Sc$^{3+}$ by Ti$^{4+}$ in Sr$_{2}$ScFeAsO$_{3}$, Ca$_{2}$ScFeAsO$_{3}$ and Sr$_{3}$Sc$_{2}$Fe$_{2}$As$_{2}$O$_{5}$ on their electrical properties. High level of doping results in an increased carrier concentration and leads to the appearance of superconductivity with the onset of T$_{c}$ up to 45 K.Comment: 8 pages, 4 figures, 2 new figure

Electron transport, penetration depth and upper critical magnetic field of ZrB12 and MgB2

We report on the synthesis and measurements of the temperature dependence of resistivity, R(T), the penetration depth, l(T), and upper critical magnetic field, Hc2(T), for polycrystalline samples of dodecaboride ZrB12 and diboride MgB2. We conclude that ZrB12 as well as MgB2 behave like simple metals in the normal state with usual Bloch-Gruneisen temperature dependence of resistivity and with rather low resistive Debye temperature, TR=280 K, for ZrB12 (as compared to MgB2 with TR=900 K). The R(T) and l(T) dependencies of ZrB12 reveal a superconducting transition at Tc=6.0 K. Although a clear exponential l(T)dependence in MgB2 thin films and ceramic pellets was observed at low temperatures, this dependence was almost linear for ZrB12 below Tc/2. These features indicate s-wave pairing state in MgB2, whereas a d-wave pairing state is possible in ZrB12. A fit to the data gives a reduced energy gap 2D(0)/kTc=1.6 for MgB2 films and pellets, in good agreement with published data for 3D \pi - sheets of the Fermi surface. Contrary to conventional theories we found a linear temperature dependence of Hc2(T) for ZrB12 (Hc2(0)=0.15 T).Comment: 8 pages, 10 figures, submitted to JET

Ovarian reserve diminished by oral cyclophosphamide therapy for granulomatosis with polyangiitis (Wegener's)

Objective Standard treatment for severe granulomatosis with polyangiitis (Wegener's) (GPA) is daily oral cyclophosphamide (CYC), a cytotoxic agent associated with ovarian failure. In this study, we assessed the rate of diminished ovarian reserve in women with GPA who received CYC versus methotrexate (MTX). Methods Patients in the Wegener's Granulomatosis Etanercept Trial received either daily CYC or weekly MTX and were randomized to etanercept or placebo. For all women ages <50 years, plasma samples taken at baseline or early in the study were evaluated against samples taken later in the study to compare levels of anti‐Müllerian hormone (AMH) and follicle‐stimulating hormone (FSH), endocrine markers of remaining egg supply. Diminished ovarian reserve was defined as an AMH level of <1.0 ng/ml. Results Of 42 women in this analysis (mean age 35 years), 24 had CYC exposure prior to enrollment and 28 received the drug during the study. At study entry, women with prior CYC exposure had significantly lower AMH, higher FSH, and a higher rate of early menstruation cessation. For women with normal baseline ovarian function, 6 of 8 who received CYC during the trial developed diminished ovarian reserve, compared to 0 of 4 who did not receive CYC ( P < 0.05). Changes in AMH correlated inversely with cumulative CYC dose ( P < 0.01), with a 0.74 ng/ml decline in AMH level for each 10 gm of CYC. Conclusion Daily oral CYC, even when administered for less than 6 months, causes diminished ovarian reserve, as indicated by low AMH levels. These data highlight the need for alternative treatments for GPA in women of childbearing age.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/88079/1/20605_ftp.pd

Electronic and Magnetic Structures of Chain Structured Iron Selenide Compounds

Electronic and magnetic structures of iron selenide compounds Ce2O2FeSe2 (2212\ast) and BaFe2Se3(123\ast) are studied by the first-principles calculations. We find that while all these compounds are composed of one-dimensional (1D) Fe chain (or ladder) structures, their electronic structures are not close to be quasi-1D. The magnetic exchange couplings between two nearest-neighbor (NN) chains in 2212\ast and between two NN two-leg-ladders in 123\ast are both antiferromagnetic (AFM), which is consistent with the presence of significant third NN AFM coupling, a common feature shared in other iron-chalcogenides, FeTe (11\ast) and KyFe2-xSe2 (122\ast). In magnetic ground states, each Fe chain of 2212\ast is ferromagnetic and each two-leg ladder of 123\ast form a block-AFM structure. We suggest that all magnetic structures in iron-selenide compounds can be unified into an extended J1-J2-J3 model. Spin-wave excitations of the model are calculated and can be tested by future experiments on these two systems.Comment: 6 pages, 6 figures, 2 table

High - Temperature Superconductivity in Iron Based Layered Compounds

We present a review of basic experimental facts on the new class of high - temperature superconductors - iron based layered compounds like REOFeAs (RE=La,Ce,Nd,Pr,Sm...), AFe_2As_2 (A=Ba,Sr...), AFeAs (A=Li,...) and FeSe(Te). We discuss electronic structure, including the role of correlations, spectrum and role of collective excitations (phonons, spin waves), as well as the main models, describing possible types of magnetic ordering and Cooper pairing in these compounds.Comment: 43 pages, 30 figures, review talk on 90th anniversary of Physics Uspekh

Tomography in soil science

The main advantages of applying computed tomography to studying soil samples include non-invasiveness, independence of the moisture content in the samples and the possibility for mathematical modelling. The methodological problems of this imaging technique include restrictions of the sample size, resolution limitations and segmentation difficulties