Effect of Nd doping on the crystallographic, magnetic and magnetocaloric properties of NdxGd3-xCoNi

The crystal structure, magnetic and magnetocaloric properties, and the critical behavior of representative compounds in the pseudo-ternary NdxGd3-xCoNi series have been investigated (x = 0.15, 0.5, 1.0, 1.5). All these phases are isotypic with the parent compound Gd3CoNi, crystallizing with the monoclinic Dy3Ni2-type (mS20, C2/m, No. 12). All samples present a paramagnetic to ferromagnetic (PM-FM) second order phase transition with decreasing Curie temperature as the Nd concentration is increased (TC = 171 K, 150 K, 120 K and 96 K, respectively) and, at lower temperatures, there is a spin reorientation which leads to a complex magnetic ground state. The critical exponents (beta, gamma, delta) have been retrieved for the PM-FM transitions. On the one hand, in x = 0.15, 0.5, 1.5 the value of γ ≈ 1 indicates that the magnetic interactions are long-range order while the values of β point to a certain deviation from the 3D-Heisenberg universality class; on the other hand, NdGd2CoNi has a particular critical behaviour, as β is close to the Mean Field model while γ is close to the uniaxial 3D-Ising one. Concerning the magnetocaloric properties, the magnetic entropy change and refrigerant capacity present competitive values, interesting for cryogenic applications. Finally, the thermal diffusivity values of these compounds are extremely good for practical magnetocaloric refrigeration systems, as they are in the range 1.5-3 mm2/s.This work has been supported by Departamento de Educación del Gobierno Vasco (Project No. IT1430-22)

Klasifikasi Tanah Berdasarkan Taksonomi Tanah 2014 Di Desa Sembahe Kecamatan Sibolangit

Sembahe is believed to have a great potential particularly in agricultural sector. In order to discover this potent it is necessary to classify the soilfirst by using USDA Soil Taxonomy 2014th edition which has not been done before. This research conducted in between December 2013 and February 2014. The soil profiles was made from two representative location. The first is located at 03020\u2740” S 98035\u2730” E, with altitude 231 meter above mean sea level. Meanwhile the second is located at 03020\u2742” S 98035\u2705” E withaltitude 294 meter above mean sea level. Morphological properties identified by describing the soil profiles using manual book while physical and chemical properties identified at laboratory. Soil samples was taken from each horizon at every profiles and analyzed for particle size distribution, bulk density, organic carbon, exchangeable cations (Ca2+, Mg2+, K+, and Na+), pH in a 1:2 soil:water ratio, pH in KCl solution, phosphate retention, and also kation exchange capacity (CEC).The results show that the soil in Sembahe Village at profile I classified as Inceptisols Order, Udepts Sub Order,Humudepts Great Group, and Cumulic Humudepts Sub Group, andat profile II classified as Inceptisols Order, Udepts Sub Order, Dystrudepts Great Group, and Typic Dystrudepts Sub Group

Materials Chemistry of Nanocubes and Mesoporous Silicas: Characterization and Adsorption Studies

Metal oxides (MO) and their surfaces play a vital role in numerous phenomena, including metal surface passivation, catalysis, integrated optoelectronic technology, and pollution monitoring via solid-state gas sensing. This experimental study seeks to aid in the development of accurate and predictive theoretical models of the potential energy surfaces described in the interaction of these small molecules with the magnesium oxide (MgO) substrate. MgO, with its structural simplicity and capacity to be fabricated with a predominantly (100) exposed face, is an ideal representative of the MO family popular for both experimental and theoretical studies. Using high-resolution volumetric adsorption isotherms, a thermodynamic investigation of n-butane and 1-butene on MgO systems resulted in the accurate determination of the two dimensional compressibility, differential enthalpy and entropy, heat of adsorption and isosteric heat of adsorption in the temperature range between 158 K and 198 K for n-butane and between 160 K and 195 K for 1-butene. The synthesis of mesoporous silica spheres with hollow interiors has attracted much attention due to their potential application in drug delivery, encapsulation, catalysis, separation, gas adsorption, sensors, and nanodevices. Various methods have been attempted in order to develop procedures for making reproducible and dependable methods of hollow mesoporous silica particles; these include sol-gel, emulsion, and organic polymer. However, despite reports of mesoporous silica being synthesized using different templates and under various reaction conditions, there is no single mechanism, which can be used to universally explain the microscopic details of formation and growth of the uniform pore and ordered pore structure. This work seeks to investigate the role played by concentrations and ratios of the reactants and experimental conditions (such as pH temperature, and stirring speed) on the formation of mesoporous silica spheres. By using several different characterization techniques such as small angle x-ray scattering, volumetric adsorption/desorption isotherms, scanning electron microscopy, and Fourier transform infrared spectroscopy insight into the formation mechanism and the ability to produce specific and tailored mesoporous silica particles is gained

Bile acid structure-activity relationship: evaluation of bile acid lipophilicity using 1-octanol/water partition coefficient and reverse phase HPLC.

Two independent methods have been developed and compared to determine the lipophilicity of a representative series of naturally occurring bile acids (BA) in relation to their struc- ture. The BA included cholic acid (CA), chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA), deoxycholic acid (DCA), hyodeoxycholic acid (HDCA), ursocholic acid (UCA), hyocholic acid (HCA), as well as their glycine and taurine ami- dates. Lipophilicity was determined using a 1-octanol/water shake-flask procedure and the experiments were performed at different pH and ionic strengths and at initial BA concentrations below their critical micellar concentrations (CMC) and the water solubility of the protonated form. The experimental data show that both the protonated (HA) and ionized (A-) forms of BA can distribute in 1-octanol, and consequently a partition co- efficient for HA (logP' HA) and for A- (logP' A-) must be defined. An equation to predict a weighted apparent distribution coefficient (D) value as a function of pH and pKa has been de- veloped and fits well with the experimental data. Differences be- tween logP for protonated and ionized species for unconjugated BA were in the order of 1 log unit, which increased to 2 for glycine-amidated BA. The partition coefficient of the A- form in- creased with Na+ concentration and total ionic strength, suggest- ing an ion-pair mechanism for its partition into 1-octanol. Lipophilicity was also assessed using reverse phase chromatogra- phy (C-18-HPLC), and a capacity factor (K') for ionized species was determined. Despite a broad correlation with the logP data, some BA behaved differently. The logP values showed that the order of lipophilicity was DCA >CDCA >UDCA > HDCA > HCA>CA >UCA for both the protonated and ionized uncon- jugated and glycine-amidated BA, while the K' data showed an inversion for some BA, i.e., DCA>CDCA >CA> HCA> UDCA > HDCA >UCA. The logP data fitted well with other in- direct measurements of BA monomeric lipophilicity such as al- bumin binding or accessible total hydrophobic surface area data calculated by energy minimization and molecular computer graphics. Differences between unconjugated and amidated BA are consistent with the presence of an amide bond and a lower pKa when pH dependence was studied. Capacity factors, on the other hand, were related to properties of BA micelles such as cholesterol-solubilizing capacity and membrane disruption, reflecting the BA detergency. The extrapolation of these data to biological phenomena must carefully consider the experimental conditions in which the interaction occurs, Le., total BA concen- tration, ionic strength, Na+ concentration, and pH, which in turn determine the BA species existing in solution that coul

Coexistence of magnetism and superconductivity in CeRh1-xIrxIn5

We report a thermodynamic and transport study of the phase diagram of CeRh1-xIrxIn5. Superconductivity is observed over a broad range of doping, 0.3 < x < 1, including a substantial range of concentration (0.3 < x <0.6) over which it coexists with magnetic order (which is observed for 0 < x < 0.6). The anomalous transition to zero resistance that is observed in CeIrIn5 is robust against Rh substitution. In fact, the observed bulk Tc in CeRh0.5Ir0.5In5 is more than double that of CeIrIn5, whereas the zero-resistance transition temperature is relatively unchanged for 0.5 < x < 1