Cationic Mobility Via Cation-Exchange Mechanism on Poly(8-Hydroxyquinoline) Matrix

The insertion of Al(III) cation into a poly(8-Hydroxyquinoline) (PHQ) instead of some metal ions such as Co(II), Ni(II), Zn(II) or Fe(III) ions via cation-exchange mechanism has been studied by several techniques. The presence of Al(III) and the absence of Co(II) cations has been proved by elemental analysis of the polymer chelates product. Molecular mechanics (MM+) calculations showed that the potential energy (PE, kJ mol⁻¹) of the optimum molecular geometric structure (OMG) of the PHQ–Al(III) matrix is about seventy-six (76.185) greater than the PE of the PHQ–Co(II) complex. The TGA thermograms show that the PHQ–Al(III) matrix is thermally unstable than the PHQ–Co(II) complex under the same conditions. These observations indicate that the PHQ–Al(III) is expanded coil-like form. So, the thermal decomposition of PHQ–Al(III) complex is easy than the compacted coil-likes form of PHQ–Co(II) complex. The incorporation of Al(III) ion via cation-exchange properties have been investigated by spectrophotometric technique. The decrease of the absorbance at about ~370 nm of PHQ–Co(II) complex associated with increasing concentration of Al(III) revealed the replacement of that metal ion by Al(III) into PHQ chain. The cation-exchange constant (K _ex) of the divalent ions [Ni(II), Co(II), Cr(II), Zn(II), Mn(II), Mg(II) and Cu(II)] from PHQ–M(II) by the additions of Al(III) according to the following series: Ni(II) > Co(II) > Cr(II) > Cu(II) > Zn(II) > Mn(II) > Mg(II).     

Analytical approximation of nonlinear vibration of string with large amplitudes

Study of nonlinear problems in strings with large amplitude is a very important research area in many fields of physics and engineering. variational approach method (VAM) is in particular selected because the method is appropriate to solve nonlinear vibration of a constanttension string. VAM is an explicit method with high capability for resolving strong nonlinear oscillation system problems. It has been found that VAM is well suited for a range of parameters and the approximate frequencies and periodic solutions show a good agreement with the exact ones. This paper compares the various aspects of VAM in relative to exact approaches and higher-order approximate solutions for the constant-tension string. The comparison indicates that VAM is very fast, effective and convenient. The method does not require any linearization or small perturbation, and it leads to high accuracy of the solutions in a single iteration.     

Full-Potential Calculation of Structural, Electronic, and Thermodynamic Properties of Fluoroperovskite \text{ CsMF}_{3} (M?=?Be and Mg)

The structural and electronic properties of the cubic fluoroperoveskite $\text{ CsBeF}_{3}$ and $\text{ CsMgF}_{3}$ have been investigated using the full-potential-linearized augmented plane wave method within the density functional theory. The exchange-correlation potential was treated with the local density approximation and the generalized gradient approximation. The calculations of the electronic band structures show that $\text{ CsBeF}_{3 }$ has an indirect bandgap, whereas $\text{ CsMgF}_{3}$ has a direct bandgap. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the effect of pressure $P$ and temperature $T$ on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature, and the heat capacity for $\text{ CsBeF}_{3}$ and $\text{ CsMgF}_{3}$ compounds are investigated for the first time.     

New developments in predicting stage–discharge curves, velocity and boundary shear stress distributions in open channel flow

The stage–discharge curve, depth-averaged velocity and boundary shear stress distributions are required to be determined for flood alleviation schemes. These parameters are hard to predict because of the three-dimensional (3-D) aspects of flow in open channels. This paper proposes a new approach for modelling open channel flow based on the Shiono and Knight Method (SKM), which is a depth-averaged model based on the governing Navier–Stokes equations. The modelling philosophy is applied to natural rivers and artificial channels both in inbank and overbank flow conditions. Accurate results are obtained when compared with field data and experimental measurements. Modelling philosophies are presented for the three calibration coefficients of the SKM. These coefficients represent the most important features of the 3-D flow mechanism.     

Structural stabilities,elastic and thermodynamic properties of Scandium Chalcogenides via first-principles calculations

The high-pressure structural (B1–B2) phase transition and the elastic properties of ScS and ScSe are studied using the full-potential augmented plane wave plus local orbitals method (FP-APW + LO) with the generalized-gradient approximation (GGA) exchange-correlation functional. The elastic constants and their pressure dependence are calculated following the total energy variation with strain technique. The stability and the ductility mechanisms for these compounds are discussed via the electronic density of states (DOS) and the elastic constants C_ij. The thermodynamic properties of (B1) structure are predicted through the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variation of bulk moduli, the thermal expansion coefficient, the heat capacities and the Debye temperature with pressure and temperature are successfully obtained. To our knowledge this is the first quantitative theoretical prediction of the elastic, high pressure and thermal properties for the investigated compounds and still awaits experimental confirmations.     

Changes in the arterial blood pressure, heart rate and normal ECG parameters of rat after envenomation with Egyptian cobra (Naja haje) venom

Haemophilus somnus is able to survive and multiply in bovine blood monocytes (BBM) and alveolar macrophages (BAM), but the mechanisms used by H. somnus to evade killing mechanisms of bovine mononuclear phagocytes are not completely understood. To study the bactericidal ability of bovine mononuclear phagocytes following interaction with H. somnus, in vitro assay systems were developed to detect the luminol-dependent chemiluminescence response (LDCL) and nitric oxide (NO) production of BBM and BAM. Live logarithmically growing or stationary phase H. somnus inhibited the LDCL of BBM and BAM costimulated with opsonized Staphylococcus aureus. Inhibition of the LDCL response of BBM and BAM was not mediated by live H. somnus opsonized with hyperimmune serum, or by killed bacteria. H. somnus stimulated both BBM and BAM to produce NO at levels comparable with Escherichia coli lipopolysaccharide. While NO was being produced, viable H. somnus could still be isolated from the cell cultures. The ability of H. somnus to inhibit LDCL of both BBM and BAM, and resistance to NO killing may be an important mechanism that contributes to survival of the organism following ingestion by bovine mononuclear phagocytes.     

Isolierung, Reinigung and Charakterisierung einer endo-Pectinlyase (endo-PL)

Zusammenfassung In dieser Arbeit wurde mittels Chromatofocussierung eine endo-Pectinlyase (PL) impräparativen Maßstab aus dem technischen Enzympräparat Pectinex Ultra SP-L isoliert and durch die wichtigsten physikalisch-chemischen and biochemischen Eigenschaften charakterisiert. Ihre Reinheit wurde durch analytische isoelektrische Focussierung und typische biochemische Reaktionen nachgewiesen. Für die PL wurden folgende Konstanten bestimmt: IP 3,9;K _m 1,91 mg/ml andV _max 0,88/min. Die pH-Optima lagen bei Verwendung von Apfelpectin mit einem Veresterungsgrad (VE) von 71 % bzw. von hochver estertem Pectin (VE=94%) bei pH 6,0 bzw. bei pH 8,5, die Temperatur-Optima bei 60° C bzw. 65° C. Die PL wies eine relativ hohe Temperatur- und pH-Stabilität auf. Die PL-Aktivität wurde deutlich durch Na⁺-Ionen gesteigert.

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Isolation, purification and characterization of an endo-pectinlyase (endo-PL)

Summary This paper describes an endo-pectinlyase isolated on a preparative scale from the commercial enzyme preparation Pectinex Ultra SP-L by using chromatofocusing. The most important biochemical and physico-chemical properties are presented. The purity of this endo-pectinlyase was proved by analytical isoelectric focusing and by typical biochemical reactions. The following constants were determined: pI 3.9, Km 1.91 mg/ml andV _max0.88 min^–1. The enzyme has a pH optimum of 6.0 with 71 % esterified apple pectin and of 8.5 with a highly (94%) esterified pectin. Temperature optima with these two substrates were 60° C and 65° C respectively. The enzyme showed a relatively high pH and temperature stability. Its activity was increased considerably in the presence of Na⁺ ions.

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Fran Rengang Zhou, landwirtschaftliche Akademie Shijiazhuang Hebei (V.R. China), z. Zt. als Stipendiatin der chinesischen Regie rung an der Universitat Hohenheim

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H. Omran, Suez Canal Universitat Ismailia (Agypten), z. Zt. als Stipendiat der Alexander von Humboldt-Stiftung an der Universitat Hohenheim