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Notes: The magnetic properties of a material are affected by the type of atomic order present in the sample. In particular, the atoms of one kind change their magnetic behavior depending on the composition of its first-neighbor shell. The analysis of magnetic samples by neutron diffuse scattering allows us to separate the atomic short-range order component from the magnetic component, but simultaneously we can study the correlations that affect the magnetic properties of materials. Using neutron-scattering data, we have analyzed the atomic short-range order in several samples where the host is Pd and the impurity is Mn. This analysis allows us to see the effects that this order has on the magnetic properties. © 1999 American Institute of Physics.

Notes: A sol–gel synthesis method based on the diol route is reported here for the fabrication of strontium bismuth tantalate (SBT, SrBi2Ta2O9) ferroelectric thin films. A tantalum penta-glycolate (TPG)-based sol is synthesized, which is air stable and has low toxicity. The structure of the TPG compound is studied by nuclear magnetic resonance (NMR) spectrometry, and the results show that TPG contains a tantalum cation bonded to five diol groups. The molecular association of the TPG derivatives in the sol, through the terminal hydroxyl groups of the diol ligands, is responsible for its transformation into a gel. Other metal compounds can be easily added to the TPG-based sols for the preparation of air-stable and precipitate-free multicomponent solutions. These solutions are precursors of complex oxide materials. In this paper, SBT thin films have been prepared by this sol–gel method. These films develop a layered perovskite structure after crystallization. The films have a remanent polarization of Pr∼10 μC/cm2, a coercive field of Ec∼65 kV/cm, and are fatigue free up to ∼1010 cycles.

Notes: A case of cutaneous alternariosis due to Alternaria alternate in a 47-year-old man who had the CREST (calcinosis, Raynaud's phenomenon, oesophageal dysfunction, sclerodactyly and telangiectasia) syndrome with pulmonary hypertension is presented. The patient, who lived in a rural area and was receiving prostacycline by continuous infusion, prednisone and azathioprine for his underlying disease, showed cutaneous lesions of the lower extremities spreading from the knees to the ankles. The patient was successfully treated with high doses of oral itraconazole.

Notes: Neutron scattering data for dilute PdMn, PdCo, and PdFe alloys show forward peaks at small values of K, which indicate an inhomogeneous distribution of the magnetization in these alloys. These inhomogeneities indicate the existence of magnetization clouds that produce the ferromagnetism in these materials; the shape of the peaks at small K also suggest a quasielastic contribution to the neutron diffuse scattering. We, therefore, calculated the neutron scattering cross sections for these alloys using a local moment model; we also developed an analytic expression for the magnetization clouds that can be compared with experimental results. The calculations were made using Monte Carlo methods in the dilute alloy region of impurity concentration. © 1996 American Institute of Physics.

Notes: Pd and Pt have been shown to be highly polarizable when mixed with ferromagnets like Ni, Fe, and Co. In these alloys the total moment, or magnetization cloud, is produced by the magnetic moment plus the induced moment on the surrounding atoms. With diffuse magnetic scattering of neutrons, it is possible to measure these magnetization clouds, M(K), as Fourier transform of the moments; M(K) represents the site occupation magnetic moment correlation. We consider that the atoms of the matrix polarize around the atoms of the impurity, following the orientation of its moments and forming giant moments. To compare with experimental data, we obtained an expression for the magnetic moments assuming a local magnetic environment. We then developed an expression for the magnetization cloud that includes the total moment associated with a giant moment, M(0), determined by magnetization measurements; we used M(0)=dμ/dc, where μ is the average moment of the alloy and c the impurity concentration, to establish a relation between neutron and magnetization measurements. © 1997 American Institute of Physics.

Notes: Crystal structure solution by anomalous dispersion methods has been greatly facilitated using the rapidly tunable station 9.5 at the Daresbury SRS. Both SIROAS and MAD techniques, with IP data, have been used in the phasing of a brominated nucleotide and a seleno deaminase, respectively. The electron density maps in each case are interpretable. Throughput of projects could be improved upon with a better duty cycle detector. Another category of data collection is that at very high resolution. Detailed structure refinement pushes the limits of resolution and data quality. Station 9.5 has been used to collect high resolution (1.4 A(ring)) native data for the protein concanavalin A. This utilized very short wavelengths (0.7 A(ring)), the image plate, and crystal freezing. A total of 155 407 measurements from two crystals benefited from the on-line nature of the IP detector device, but a slow and quick pass are required to capture the full dynamic range of the data. There are data seen to 1.2 A(ring) and beyond for a pure Mn substituted form of the protein, but a higher intensity still is required to actually record these data. By comparison, trials at CHESS, on a multipole wiggler (station A1) with a CCD (without image intensifier) system, yield native concanavalin A data to 0.98 A(ring) and beyond. This demonstrates that the combination of yet higher intensity and the ease of use of a CCD offers worthwhile improvements; in this case an increase in the data by a factor of (1.4/0.98)3, thus at least doubling the data to parameter ratio for protein structure model refinement and potentially opening up direct structure determination of proteins of the size of concanavalin A (25 kDa).Finally, possibilities at ESRF and further detector developments, such as mosaic CCDs and scintillator coatings, offer further impetus for the field. These include more intense rapidly tunable beams for anomalous dispersion-based structure solution and "ideal'' higher resolution data collection and reactivity studies. ESRF BL19 is described; facilities on BL19 will include a system for freezing and storing crystals at cryogenic temperatures, so that data can be recorded from the same crystal on different runs. Overall, there have been tremendous strides made in this field in the last 15 years, and yet further improvements are to come. © 1995 American Institute of Physics.

Notes: The growth of cultivation (strawberries and citrus fruits) in the coastal region of the Huelva province of Spain in the last 10 years has meant an increase in the demand of water from the Ayamonte-Huelva aquifer system. It has also meant the introduction of an excess of nitrogen via fertilizers from farming.The system now has two problems: salt-water intrusion in the southern sector (González and Romero, 1991; González, 1992); and a general increase in the nitrate content in the saturated zone. This second problem has led to average concentrations of nitrates in the aquifer above potable limits (50 ppm), reaching local values near to 400 ppm of NO3-(González and Romero, 1991; Grande et al., 1993).This paper delineates the sphere of influence of the two factors being considered (salt-water intrusion and agricultural contamination) on the different variables studied. The proximity between both factors is justified for each of the contaminating processes.