Possible relationships between groundwater arsenic concentration and alluvial sediment characteristics in a ∼19 km2 area in West Bengal have been investigated using a combination of hydrogeochemical, lithogeochemical and geophysical techniques. Arsenic hotspots, typically associated with elevated groundwater Fe and Mn, were found to be correlated to some extent with old river channels (abandoned meanders, oxbow lakes), where sandy aquifers included intercalated fine-grained overbank deposits, rich in As, Fe, Mn and Corg. Otherwise no demonstrably significant overall differences in any of lithology, grain-size distribution, mineral composition or Fe, Mn and organic C content of the sediments were found between two representative sites with contrastingly low (<50 μg 1—1) and high (>200 μg 1—1) As groundwater contents.

Our results are consistent with microbially mediated redox reactions controlled by the presence of natural organic matter within the aquifer and the occurrence of As-bearing redox traps, primarily formed by Fe and Mn oxides/hydroxides, being the most important factors which control the release of As into shallow groundwaters at the study site.

The present study focuses on a quantitative analysis of electrical resistivity in monovalent-doped manganites La1−xAgxMnO3 (x = 0.05 and 0.1). The electrical resistivity data in the ferromagnetic (FM) metallic phase are analyzed by considering a temperature-independent inelastic scattering of the electrons (due to domain and grain boundaries, defects, etc.) and other temperature-dependent elastic scattering mechanisms (electron–electron, electron–phonon, and electron–magnon). The Debye and Einstein temperatures are deduced from the model Hamiltonian containing potential energy contribution from the long-range Coulomb, van der Waals (vdW) interaction, and short-range repulsive interaction up to the second-neighbor ions. The electron–phonon scattering partially describes the reported FM metallic resistivity behavior with temperature for La1−xAgxMnO3 (x = 0.05 and 0.1). The T2 and T4.5 terms accounting for electron–electron and electron–magnon interactions are essential for the correct description of resistivity. The Mott–Ioffe–Regel criterion for metallic conductivity is valid, and kFl ∼ 1, εFτ ∼ 1.

A new compound Er0.33Sr1.67Ni0.8Cu0.2O4−δ (ErSr5Ni2.4Cu0.6O11) was prepared using the conventional solid state method and annealed at 1423 K in 1 atm of oxygen gas flow. The oxygen non-stoichiometry (δ = 0.47) was determined by iodometric titration. Rietveld refinement using powder X-ray diffraction data confirms that the sample adopts the K2NiF4-type structure (space group I4/mmm (Z = 2), a = 3.760 56(4) and c = 12.3889(1) Ǻ). The final reliability factors were: Rwp = 10.75%, χ2 = 2.51, Rp = 14.80%, RB = 4.77% and RF = 2.73%. Four probe electrical resistivity measurements were performed vs. temperature in the range of 320–540 K. A semiconducting behaviour over the whole range of temperature, with a maximum conductivity of 0.026 S cm−1 is observed at 439 K.

A new member of the LnMIn5 family, ErCoIn5, has been synthesized by a flux-growth method. The structure of ErCoIn5 was determined by single crystal X-ray diffraction. It crystallizes in the tetragonal space group P4/mmm, Z = 1, with lattice parameters a = 4.5400(4) and c = 7.3970(7) Å, and V = 152.46(2) Å3. Electrical resistivity data show metallic behavior. Magnetic susceptibility measurements show this compound to be antiferromagnetic with TN = 5.1 K. We compare these experimental results with those of LaCoIn5 in an effort to better understand the effect of the structural trends observed on the transport and magnetic properties.