On the Crystal Distortion in Several Spinel Systems(Physics)

The composition and temperature dependence of cooperative Jahn-Teller distortions have been studied in the spinel mixtures CuFe_Zn_xTi_xO_4. CuFe_Zn_xGe_xO_4, and CuFe_Ga_O_4 which contain Cu^-ions in B-sites In the former two cases the tetragonal distortion rapidly disappears with the substitution of a small amount of Fe^ by Zn^Ti^ or Zn^Ge^. Electrostatie potentials in these systems have been calculated from the measured values of the u-parameter and the cause of the non-distortion has been investigated on the basis of the intrinsic energy of the crystal. The effective Bohr magneton number of Cu^-ions of the spinel CuFe_Ga_O_4 deduced from the 1/x-T curve takes a value close to the calculated one corresponding to the "spin-only" state of Cu^ions even above the cubic-to-tetragonal transformation temperature

Disseminating genetically modified (GM) maize technology to smallholder farmers in the Eastern Cape province of South Africa: extension personnel’s awareness of stewardship requirements and dissemination practices

Advice and technical information from extension services are critical in promoting new technologies and their adoption by farmers. This study determined extension personnel’s awareness of GM maize technology and the associated extension services they provide to smallholder GM maize farmers in the Eastern Cape province of South Africa. Face-to-face interviews were conducted with extension staff of the Department of Rural Development and Agrarian Reform (DRDAR) in the province. Results indicated that inadequate training of extension personnel on GM maize technology influenced their perceptions of GM maize technology and awareness of its stewardship requirements. Generally, personnel had a low level of awareness of GM maize technology as a pest control strategy. Awareness of GM maize stewardship requirements amongst extension personnel was also low. These extension personnel disseminated GM maize technology, which they generally perceived as a high-yield technology, to smallholder farmers using non-participatory approaches and media sourced from GM seed companies. The findings of this study suggest that ensuring safe and sustainable adoption of GM maize technology on smallholder farms will require a more participatory extension approach that emphasizes smallholder farmers’ access to information as well as the training of extension personnel on the stewardship requirements and dissemination practices associated with GM maize cultivation.Keywords: Dissemination, extension, GM maize technology, smallholders, stewardshi

Oscillations of the superconducting critical current in Nb-Cu-Ni-Cu-Nb junctions

We report on experimental studies of superconductor-ferromagnet layered structures. Strong oscillations of the critical supercurrent were observed with the thickness variation of the ferromagnet. Using known microscopic parameters of Ni, we found reasonable agreement between the period of oscillations and the decay of the measured critical current, and theoretical calculations.Comment: 5 page

Extraction and characterization of novel lignocellulosic fibers from Thespesia lampas plant

In this work, the lignocellulosic fibers from the plant Thespesia lampas were extracted and investigated in detail. The prime objective of this work was to study the effect of alkali treatment on the chemical composition, tensile properties, morphological and structural changes, and thermal degradation of Thespesia lampas fibers. Chemical analysis, FT-IR, and 13C CP-MAS NMR spectroscopic studies indicated lowering of amorphous hemicellulose content on alkali treatment. Wide-angle X-ray diffraction studies indicated increase in crystallinity of the fibers on alkali treatment. The tensile strength and modulus of the fibers and thermal stability increased on alkali treatment. Scanning electron micrographs revealed roughening of the surface of the fibers due to the removal of the hemicellulose layer on alkali treatment. Tensile properties of Thespesia fibers were compared to those of other important natural fibers, and it was indicated as an alternative suitable source for composite construction

Soft Ferromagnetic Properties of Some Amorphous Alloys

In rapidly quenched amorphous alloys of (Fe_Co_x)_P_C_7 and (Fe_Co_x)_Si_B_, it was found that the zero magnetostrictive alloys are remarkably soft magnetic materials, while the magnetostrictive alloys have rather large coercive force. To investigate the effect of magnetostriction on the properties of the B-H loop, some fundamental magnetic properties in these alloys were studied. The magnetic domain pattern observed by Bitter\u27s method shows a periodic domain structure consisting of 180° and maze domain walls (the periodicity can be seen along the specimen long axis) in all the magnetostrictive alloys, suggesting the existence of magnetic anisotropy whose easy axis varies locally. The estimated value of the anisotropy energy varies with x similar to the composition dependence of magnetostriction. Torque measurements support the above estimation. The coercive force also varies with x and is nearly proportional to the magnetostriction to magnetization ratio. It is, therefore, considered that the anisotropy is caused by the anisotropic internal stress field, and that the stress fluctuation which inevitably exists is responsible for the large coercive force

Microbial Analysis and Sensory Attributes of Garri Produced and Marketed in Bida Niger State, Nigeria

Garri is one of the most preferred cassava products due to its less expensive nature, less bulky, easy to cook and not readily perishable. This study was carried out to ascertain the microbial analysis and sensory attributes of garri produced and marketed in Bida Niger state, Nigeria. The collected samples were analyzed using standard methods and procedures. The results show moisture content of the garri sample ranged from 7.0 to 11.0%. The swelling index ranged from 2.0 to 4.0%.  The mean bacteria count ranged from 4.04±3.98 to 4.11±3.98 Cfu/g and the mean fungal count ranged from 3.57±3.50 to 3.62±3.50 Cfu/g. There was no significant difference (p>0.05) in the mean bacterial and fungal count observed among the samples from the studied garri production area. The bacterial isolates encountered were Micrococcus sp., Streptococcus sp., Bacillus sp., Staphylococcus aureus and Shigella sp. While the fungal isolates were Aspergillus flavus, Aspergillus niger, Cladosporium sp., Rhizopus sp., Penicillium sp. and Fusarium sp. Most of the isolates are of public health importance and there is need to maintain a clean, safe personal and environmental hygiene in garri producing areas of Bida Niger state to avoid microbial contamination

Thermodynamics and Phase Diagrams of layered superconductor/ferromagnet nanostructures

We study the thermodynamics of clean, layered superconductor/ferromagnet nanostructures using fully self consistent methods to solve the microscopic Bogoliubov-deGennes equations. From these self-consistent solutions the condensation free energies are obtained. The trilayer SFS junction is studied in particular detail: first order transitions between 0 and $\pi$ states as a function of the temperature $T$ are located by finding where the free energies of the two phases cross. The occurrence of these transitions is mapped as a function of the thickness $d_F$ of the F layer and of the Fermi wavevector mismatch parameter $\Lambda$. Similar first order transitions are found for systems with a larger number of layers: examples are given in the 7 layer (3 junction) case. The latent heats associated with these phase transitions are evaluated and found to be experimentally accessible. The transition temperature to the normal state is calculated from the linearized Bogoliubov-deGennes equations and found to be in good agreement with experiment. Thus, the whole three dimensional phase diagram in $T,d_F,\Lambda$ space can be found. The first order transitions are associated with dips in the transition temperature $T_c$ to the non-superconducting state, which should facilitate locating them. Results are given also for the magnetic moment and the local density of states (DOS) at the first order transition.Comment: 15 pages, 13 figure

Development of decision support system for the diagnosis of arthritis pain for rheumatic fever patients: Based on the fuzzy approach

Developing a Decision Support System (DSS) for Rheumatic Fever (RF) is complex due to the levels of vagueness, complexity and uncertainty management involved, especially when the same arthritis symptoms can indicate multiple diseases. It is this inability to describe observed symptoms precisely that necessitates our approach to developing a Decision Support System (DSS) for diagnosing arthritis pain for RF patients using fuzzy logic. In this paper we describe how fuzzy logic could be applied to the development of a DSS application that could be used for diagnosing arthritis pain (arthritis pain for rheumatic fever patients only) in four different stages, namely: Fairly Mild, Mild, Moderate and Severe. Our approach employs a knowledge-base that was built using WHO guidelines for diagnosing RF, specialist guidelines from Nepal and a Matlab fuzzy tool box as components to the system development. Mixed membership functions (Triangular and Trapezoidal) are applied for fuzzification and Mamdani-type is used for the fuzzy reasoning process. Input and output parameters are defined based on the fuzzy set rules

Theory of proximity effect in superconductor/ferromagnet heterostructures

We present a microscopic theory of proximity effect in the ferromagnet/superconductor/ferromagnet (F/S/F) nanostructures where S is s-wave low-T_c superconductor and F's are layers of 3d transition ferromagnetic metal. Our approach is based on the solution of Gor'kov equations for the normal and anomalous Green's functions together with a self-consistent evaluation of the superconducting order parameter. We take into account the elastic spin-conserving scattering of the electrons assuming s-wave scattering in the S layer and s-d scattering in the F layers. In accordance with the previous quasiclassical theories, we found that due to exchange field in the ferromagnet the anomalous Green's function F(z) exhibits the damping oscillations in the F-layer as a function of distance z from the S/F interface. In the given model a half of period of oscillations is determined by the length \xi_m^0 = \pi v_F/E_ex, where v_F is the Fermi velocity and E_ex is the exchange field, while damping is governed by the length l_0 = (1/l_{\uparrow} + 1/l_{\downarrow})^{-1} with l_{\uparrow} and l_{\downarrow} being spin-dependent mean free paths in the ferromagnet. The superconducting transition temperature T_c(d_F) of the F/S/F trilayer shows the damping oscillations as a function of the F-layer thickness d_F with period \xi_F = \pi/\sqrt{m E_ex}, where m is the effective electron mass. We show that strong spin-conserving scattering either in the superconductor or in the ferromagnet significantly suppresses these oscillations. The calculated T_c(d_F) dependences are compared with existing experimental data for Fe/Nb/Fe trilayers and Nb/Co multilayers.Comment: 13 pages, REVTeX4, 8 PS-figures; improved version, submitted to PR