Nanocrystalline Zn1−x Ag x O y thin films evolved through electrodeposition for photoelectrochemical splitting of water

Nanocrystalline Zn_1???x Ag _x O _y (x?=?10^??3???50?×?10^??3) thin films evolved through electrodeposition over ITO substrate have been investigated for photoelectrochemical splitting of water. Samples were characterized by XRD, EDX, SEM, AFM, UV–visible optical absorption, and Mössbauer spectral analysis. Ag incorporation led to a decrease in the band gap energy and alterations in microstructural and semiconductor properties. Raising Ag concentration in samples up to 1 % at. caused a significant reduction in density and electrical resistivity, enhanced absorption along with red shift to the band gap energy, anodic shift in flat band potential, and increased charge carrier density, enabling 1 % at. Ag-incorporated ZnO films most photosensitive by yielding highest short-circuit current, photocurrent density, and applied bias photon to current efficiency. Plausible reasons have been offered.     

Isoflavonoid glycosides from the rhizomes of Iris germanica

Four isoflavone glycosides were isolated from the rhizomes of Iris germanica. Compounds 1 and 2 are new, while compounds 3 and 4 are known isoflavone glycosides. These compounds were identified as iriskashmirianin 4'-O-beta-D-glucoside (1), nigricin 4'-O-beta-D-glucoside (2), irilone 4'-O-beta-D-glucoside (3) and iridin (4). Their structures were determined with the help of spectroscopic methods.     

Structural studies of the monoclinic dihydrogen phosphates: II. A neutron-diffraction study of TlH2PO4

A neutron-diffraction study of TlH₂PO₄ at room temperature (RT) is presented as part of an investigation of the group of monoclinic dihydrogen phosphates: NaDP, deuterated-KDP, CsDP, and TlDP (DP denotes H₂PO₄). The structure of TlDP, and the nature of its phase transition at 230 K, are discussed and compared with paraelectric CsDP — with which TlDP is nearly isomorphous at RT.     

Structural studies of the monoclinic dihydrogen phosphates: A neutron-diffraction study of paraelectric CsH2PO4

The crystal structure of paraelectric CsH₂PO₄ at room temperature is presented. As suggested by the strong deuteration-dependence of the transition temperature and the distribution of quasielastic scattering, one of the hydrogen bonds is found to be very probably (97.5%) disordered, with H-H=0.48(4)Å. This work is set in the context of the interest now being shown in the group of monoclinic dihydrogen phosphates-deuterated KDP, NaDP, the ferroelectric CsDP and the presumed ferroelectric T1DP (DP denotes H₂PO₄). Recent work on these other compounds is surveyed briefly.     

Steady laminar boundary layer of a viscous incompressible fluid in a convergent channel with distributed suction at the wall

In this paper an attempt has been made to find the solution of the boundary layer equations for two-dimensional laminar steady motion of a viscous incompressible fluid in a convergent channel (sink flow) with suction at the wall. Suction velocity v₀ (x) ～ 1/x has been imposed at the wall and an approximate solution has been obtained with the help of similarity transformation. A solution valid at a large distance from the wall and a series solution valid near the wall have been obtained and the two solutions have been joined at a suitable point. It is seen that the boundary layer thickness diminishes as the value of the suction parameter\(\lambda ( = v_0 x/\sqrt {u_1 v} )\) increases. The velocity profile and the boundary layer parameters for solid wall (λ = 0) obtained from this solution are found to be in close agreement with the profile and the parameters calculated from the known exact solution for the solid wall problem.     

Two new diterpene polyesters from Euphorbia decipiens

Two new myrsinol-type diterpene polyesters 3,5,13,17-tetra-O-acetyl-7-O-benzoyl-15-hydroxymyrsinol (1) and 3,5,13,17-tetra-O-acetyl-7-O-butanoyl-13-hydroxymyrsinol (2), with a tricyclic carbon skeleton have been isolated from Euphorbia decipiens Boiss. & Buhse. The structure elucidation of the isolated compounds was based primarily on HREIMS, EIMS, IR, UV, ID-, and 2D-NMR analyses, including COSY, HMQC, HMBC, and NOESY correlations. Compounds 1 and 2 also showed activity against urease enzyme.     

Interpretation of anomalous normal state optical conductivity of La-Sr-CuO cuprates

The observed frequency dependent optical response of hole doped cuprate La_1.85Sr_0.15CuO₄ superconductors, has been theoretically analysed. Starting from an effective two-dimensional (2D) interaction potential for superlattice of hole doped cuprates treated as a layered electron gas, the spectral function is formulated. Calculations of the optical conductivity σ(ω) have been made within the two-component scheme: one is the coherent Drude carriers responsible for superconductivity and the other is incoherent motion of carriers from one site to other leads to a pairing between Drude carriers. The approach accounts for the anomalies reported (frequency dependence of optical conductivity) in the optical measurements for the normal state. Estimating the effective mass from specific heat measurement and ε_∞ from band structure calculations for the low-energy charge density waves, the model has only one free parameter, the relaxation rate. The frequency dependent relaxation rates are expressed in terms of memory functions, and the coherent Drude carriers from the effective interaction potential lead to a sharp peak at zero frequency and a long tail at higher frequencies, i.e. in the infrared (IR) region. However, the hopping of carriers from one site to other (incoherent motion of doped carriers) yields a peak value in the optical conductivity centred at mid-IR (MIR) region. We find that both the Drude and hopping carriers in the superlattice of cuprates will contribute to the optical process of conduction in the CuO₂ planes and shows similar results on optical conductivity in the MIR as well as IR frequency regions as those revealed from experiments.     

Paeonins A and B,lipoxygenase inhibiting monoterpene galactosides from Paeonia emodi

Paeonins A and B, new monoterpene galactosides have been isolated from the chloroform-soluble fraction of the roots of Paeonia emodi and showed potent lipoxygenase inhibitory activity. The structures of 1 and 2 have been assigned on the basis of spectral analysis including one- and two-dimensional NMR techniques.     

Five new peltogynoids from underground parts of Iris bungei: a Mongolian medicinal plant

Five new peltogynoids, irisoids A-E (1-5), have been isolated from the underground parts of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods and were found to be 1,8,10-trihydroxy-9-methoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (1), 1,8-dihydroxy-9,10-dimethoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (2), 1,10-dihydroxy-8,9-dimethoxy-[1]benzopyrano-13,2-c][2]-benzopyran-7(5H)-one (3), 1,8-dihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (4), and 1,8,11-trihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (5). The structure of irisoid B (2) was established unambiguously by X-ray diffraction study.