Characterization of structure and diffusion behaviour of Ca-alginate beads prepared with external or internal calcium sources

Ca-alginate beads were prepared with either external or internal calcium sources. The structures of both beads were investigated with the aid of scanning electron microscopy (SEM) and confocal microscopy. It was shown that the beads with internal calcium source had a looser structure and bigger pore size than those with external calcium source. The attempts to interpret the difference were carried out by determining the Ca content within the beads at various times, which indicated that it was the different gelation mechanisms that caused the difference of structures of both beads. Furthermore, it was also found that the diffusion rate of haemoglobin (Hb) within the beads with an internal calcium source was faster than that of the beads with an external one, which was consistent with the observation of their structures.

Synergistic extraction of zinc(II) with mixtures of CA-100 and cyanex 272

The extraction of zinc(II) from an aqueous chloride medium has been studied using mixtures of sec-nonylphenoxy acetic acid (CA-100) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272). The results demonstrate that zinc ion is extracted into heptane as ZnA(2).2HA with CA-100, ZnL2.2HL with Cyanex 272, and ZnA(2)L(2)H(2) with synergistic mixture. The equilibrium constants of the these species have been calculated and extraction mechanisms have been proposed. Thermodynamic parameters of the extraction process were determined by the temperature coefficient of extractability. The synergistic system enhances the extraction efficiency of zinc(II) and also improves the selectivity between zinc(II) and cadmium(II).

THE EFFECT ON PHYSICAL-PROPERTIES OF THE SUBSTITUTION OF CA OR BA FOR SR IN NDSRNIO4

A new solid solution series, NdSr(1-x)M(x)NiO(4) (M = Ca: 0.0 less than or equal to x less than or equal to 1.0; M = Ba: 0.0 less than or equal to x less than or equal to 0.6), was synthesized by solid state reaction, and the structures, magnetic and electrical properties and optical spectra of this series have been studied. All the samples crystalized in tetragonal systems, with the exception of NdCaNiO4, which crystallized in the orthohombic system. IR spectra of NdSr1-xCaxNiO4 indicated that the lengths of two Ni-O bonds decrease with increasing Ca content. The electrical conduction changed from metallic-type to semiconductive-type when x greater than or equal to 0.4 (M = Ca, Ba), and the room temperature resistivities of NdSr1-xCaxNiO4 increased with the increase of Ca content. Magnetic susceptibility measurements revealed that Ni+3 ions in all the samplies were in low-spin state over the temperature range 77-300 K.

INVOLVEMENT OF CA(2+) SIGNALING PATHWAY DURING OOCYTE MATURATION OF THE NORTHERN QUAHOG MERCENARIA MERCENARIA

In many molluses, it has been found that Ca2+ signaling pathway is involved in the resumption of meiotic maturation in oocytes. To better understand the possible role of Ca2+ signaling pathway in regulating meiotic maturation in oocytes of the northern quahog Mercenaria mercenaria, free extracellular Ca2+, A23187 (calcium ionophore), verapamil (calcium channel blocker), and trifluoperazin (calmodulin antagonist) were used to incubate oocytes or serotonin-induced oocytes by pharmacological methods. Results show that extracellular Ca2+ (50 similar to 200 mM) and A23187 (1 similar to 10 mu M) can stimulate the meiotic maturation. In addition, verapamil (1 similar to 100 mu M) and trifluoperazin (10 similar to 1,000 mu M) could inhibit serotonin-induced oocyte maturation. Therefore, Ca2+ is essential for the reinitiation of meiotic maturation in oocytes of the northern quahog. Moreover, an increase i [Ca2+]i can promote meiotic maturation.

INFLUENCE OF CORE POLARIZATION ON THE ELECTRON-AFFINITY OF CA

We have developed a method, based on the use of B-spline basis sets and model potentials, for determining properties of systems with two or three electrons outside a polarizable closed-shell core. It is applied to the calculation of the electron affinity of Ca and the resulting value of 17.7 meV is in excellent agreement with the most recent experiments. It is found that the dielectronic core-valence interaction reduces the electron affinity by 39.5 meV.

Electron excitation of Ca XVII

Electron-excitation collision strengths have been calculated for transitions between the ten lowest levels of Ca XVII (2sS, 2s2p P, 2s2p P, 2pP 2p D, 2pS ). At high impact energies, where all the channels are open, the calculation was carried out in the LS-coupling approximation by means of the R-matrix method. Transitions between the fine structure levels were then determined by application of a unitary transformation to the LS-coupled K-matrices. At low impact energies, where some of the channels may be closed, an extension of the R-matrix method was employed to take account of relativistic effects directly in the scattering equations. In general, results are in good agreement with recent distorted-wave calculations. Electron-excitation rates are given for a range of electron temperatures.

A Zoologist with a Taste for the Past: The Earl of Cranbrook’s Contribution to Zooarchaeological Research in Southeast Asia

The Earl of Cranbrook (V) (then Lord Medway) was fi rst introduced to archaeological research in 1958 when he participated in excavations at the Niah Caves, Sarawak Borneo. In that same year he published a paper entitled ‘Food bone in Niah Cave excavations (-1958)’ in the Sarawak Museum Journal. Unbeknownst to him at the time, his individual and intuitive research was on a par with, if not methodologically ahead of, burgeoning studies in the fi eld of zooarchaeology that were taking place at leading academic institutions in Europe and the United States. This paper recounts and lauds the signifi cant contributions the Earl of Cranbrook has made to the establishment and furtherance of a discipline over more than 50 years. 

Letter to Colonel Robert Nelles, Commander of the 4th Regiment of Lincoln Militia from Colonel Nathaniel Coffin of York

Letter to Colonel Robert Nelles, Commander of the 4th Regiment of Lincoln Militia from Colonel Nathaniel Coffin of York. His is enquiring about the post of collector at Niagara for his son-in-law Edward Pilkington. There is a small hole in this letter which affects the text slightly, Aug. 28, 1820.