Application of Evaporation Method Using Two Tensiometers for Determining Unsaturated Hydraulic Conductivity beyond Tensiometric Range

Accurate determination of unsaturated hydraulic conductivity in low pressure head range is critical for predicting evaporation rate under localized irrigation or root water uptake under drought stress conditions. We proposed a relatively low cost and fast laboratory method to simultaneously determine water retention and hydraulic conductivity functions across a wide range of pressure heads. The method is quite similar to conventional evaporation method using two tensiometers. In addition to tensiometer readings, the proposed method uses water content profile at the end and cumulative evaporation. Experimental results for three soils with different textures showed that inversely optimized hydraulic conductivity functions agreed with K-data measured with the steady state evaporation method, indicating the reliability of the proposed method. The hydraulic conductivity functions fitted for K-data obtained by tensiometer readings with Campbell’s K(θ) function also agreed well with the reference K-data for two of the three soils, but largely deviated from those for the third soil. This indicates the importance of actual measurement of K(θ) in low pressure head range

The degree of aqueous alteration of nine CM chondrites estimated from mineralogy and chemical variations of matrix.

第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月17日（木） 国立国語研究所 2階講

Mekanisme Reaksi Asam Borat Dengan Produk Radiolisis Akibat Radiasi Sinar- Pada Temperatur 25oc

MEKANISME REAKSI ASAM BORAT DENGAN PRODUK RADIOLISIS AKIBAT RADIASI SINAR- PADA TEMPERATUR 25OC. Telah dilakukan simulasi yang bertujuan untuk memahami mekanisme reaksi antara asam borat (H3BO3) yang ditambahkan kedalam air pendingin primer PWR dengan produk radiolisis akibat radiasi dengan sinar- pada temperatur 25oC. Simulasi dilakukan dengan menggunakan perangkat lunak ‘Facsimile\u27 yang berbasis kinetika reaksi yang berkelanjutan. Sebagai masukan adalah set reaksi kimia yang terdiri dari 61 jenis reaksi dengan konstanta kecepatan reaksinya, nilai-G spesi radiolisis akibat radiasi sinar-, laju dosis 10 dan 104 Gy/s, konsentrasi awal oksigen yang berhubungan dengan sistem aerasi (0,25M), deaerasi dan konsentrasi asam borat hingga konsentrasi 1M. Luaran di program berupa seri Perubahan konsentrasi vs waktu iradiasi. Data luaran kemudian diolah menggunakan perangkat pembuat grafik ‘Origin\u27. Validasi dilakukan dengan membandingkannya dengan hasil simulasi sebelumnya. Hasil validasi menunjukkan perbedaan yang tidak signifikan, sehingga diputuskan bahwa set reaksi sekarang adalah valid. Penambahan asam borat menekan konsentrasi oksigen secara signifikan. Hubungan kenaikan logaritmik penambahan konsentrasi H3BO3 vs produk oksigen menunjukkan hubungan linear yang menurun. Dari hasil simulasi dapat dipahami bahwa penambahan H3BO3 tidak hanya mengatur reaktivitas neutron pada temperatur 25oC tetapi juga memberikan imbas positif didalam menekan konsentrasi produk oksigen yang memegang peran penting di dalam proses korosi

Dynamic fluctuations in the superconductivity of NbN films from microwave conductivity measurements

We have measured the frequency and temperature dependences of complex ac conductivity, \sigma(\omega)=\sigma_1(\omega)-i\sigma_2(\omega), of NbN films in zero magnetic field between 0.1 to 10 GHz using a microwave broadband technique. In the vicinity of superconducting critical temperature, Tc, both \sigma_1(\omega) and \sigma_2(\omega) showed a rapid increase in the low frequency limit owing to the fluctuation effect of superconductivity. For the films thinner than 300 nm, frequency and temperature dependences of fluctuation conductivity, \sigma(\omega,T), were successfully scaled onto one scaling function, which was consistent with the Aslamazov and Larkin model for two dimensional (2D) cases. For thicker films, \sigma(\omega,T) data could not be scaled, but indicated that the dimensional crossover from three dimensions (3D) to 2D occurred as the temperature approached Tc from above. This provides a good reference of ac fluctuation conductivity for more exotic superconductors of current interest.Comment: 8 pages, 7 Figures, 1 Table, Accepted for publication in PR

Experimental observation of the crystallization of a paired holon state

A new excitation is observed at 201 meV in the doped-hole ladder cuprate Sr$_{14}$Cu$_{24}$O$_{41}$, using ultraviolet resonance Raman scattering with incident light at 3.7 eV polarized along the direction of the rungs. The excitation is found to be of charge nature, with a temperature independent excitation energy, and can be understood via an intra-ladder pair-breaking process. The intensity tracks closely the order parameter of the charge density wave in the ladder (CDW$_L$), but persists above the CDW$_L$ transition temperature ($T_{CDW_L}$), indicating a strong local pairing above $T_{CDW_L}$. The 201 meV excitation vanishes in La$_{6}$Ca$_{8}$Cu$_{24}$O$_{41+\delta}$, and La$_{5}$Ca$_{9}$Cu$_{24}$O$_{41}$ which are samples with no holes in the ladders. Our results suggest that the doped holes in the ladder are composite bosons consisting of paired holons that order below $T_{CDW}$.Comment: Accepted for publication in Physical Review Letters (4 figures

Stability of Ge-related point defects and complexes in Ge-doped SiO_2

We analyze Ge-related defects in Ge-doped SiO_2 using first-principles density functional techniques. Ge is incorporated at the level of ~ 1 mol % and above. The growth conditions of Ge:SiO_2 naturally set up oxygen deficiency, with vacancy concentration increasing by a factor 10^5 over undoped SiO_2, and O vacancies binding strongly to Ge impurities. All the centers considered exhibit potentially EPR-active states, candidates for the identification of the Ge(n) centers. Substitutional Ge produces an apparent gap shrinking via its extrinsic levels.Comment: RevTeX 4 pages, 2 ps figure

Comparative Study of Regulatory T Cell Function of Human CD25+CD4+ T Cells from Thymocytes, Cord Blood, and Adult Peripheral Blood

CD25+CD4+ regulatory T cells suppress T cell activation and regulate multiple immune reactions in in vitro and in vivo studies. To define the regulatory function of human CD25+CD4+ T cells at various stages of maturity, we investigated in detail the functional differences of CD25+CD4+ T cells from thymocytes, cord blood (CB), and adult peripheral blood (APB). CB CD25+CD4+ T cells displayed low-FOXP3 protein expression level and had no suppressive activity. In contrast, CD25+CD4+ T cells from thymocytes or APB expressed high expression level of FOXP3 protein associated with significant suppressive activity. Although CB CD25+CD4+ T cells exhibited no suppressive activity, striking suppressive activity was observed following expansion in culture associated with increased FOXP3 expression and a shift from the CD45RA+ to the CD45RA− phenotype. These functional differences in CD25+CD4+ T cells from Thy, CB, and APB hence suggest a pathway of maturation for Treg in the peripheral immune system