Physicochemical study of magnesium zinc codoped-hydroxyapatite

Mg-Zn-doped hydroxyapatites in the system Ca9.4-xMg0.6Znx(PO4)6(OH)2 (x= 0, 0.1, 0.2, 0.4 and 0.6) were synthesized via sol-gel method. The obtained powder was calcined at 600°C and 700°C. X-ray diffraction (XRD) patterns and Infra-Red (IR) spectra confirmed the formation of pure hydroxyapatite up to 2% Zn content (a trace of β-pyrophosphate is detected for x=0), while a mixture of hydroxyapatite and β-TCP was formed for 4 mol%. With 6 mol%, only β-TCP formed. Moreover, at 700°C, all powders turned to be composed of solely β-TCP. The unit cell constants have also been calculated and match well with hexagonal (P63/m) hydroxyapatite

Removal of methylene blue with a highly effective hydroxyapatite-silica nanocomposite

Two Hydroxyapatite-silica nanocomposite adsorbent (HApS220 and HApS230) were successfully synthesized using sol-gel technique. The samples were characterized by powder X-ray diffraction (XRD), Infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), which confirmed the formation of a Hydroxyapatite-silica nanocomposite. The synthesized powders were then used for adsorption of methylene blue (MB). Both compounds possessed high absorption capacities, the adsorption equilibrium time is around 10 min. HApS230 sample shows higher adsorption capacity compared to HApS220. Furthermore, isotherm studies show that the adsorption used is an ion exchange process and that Temkin isotherm describes the adsorption better compared to the Langmuir and Freundlich and Dubinin-Radushkevich isotherms. Kinetics studies confirm that the adsorption follow the pseudo-second order model and chemisorption mechanism. Thermodynamics’ studies confirm that the adsorption of MB on HApS samples is a spontaneous endothermic process. The average removal effectiveness of MB reached about 89.02% (6.389 mg/g adsorption capacity) and 91.36% (6.55 mg/g adsorption capacity) for HApS220 and HApS230 respectivel

Hadron Mass Predictions of the Valence Approximation to Lattice QCD

We evaluate the infinite volume, continuum limits of eight hadron mass ratios predicted by lattice QCD with Wilson quarks in the valence (quenched) approximation. Each predicted ratio differs from the corresponding observed value by less than 6\%.Comment: 13 pages of Latex + 2 PostScript files attached, IBM/HET 92-

Organotin (IV) derivative of Piperic acid and Phenylthioacetic acid: Synthesis, Crystal structure, Spectroscopic characterizations and Biological activities

Three new organotin (IV) derivatives have been prepared from piperic and phenylthio acetic acids, the former is obtained by hydrolysis of piperine, which is extracted from black pepper. The three complexes {[n-Bu2SnO2C-(CH=CH)2-C7H5O2]2O}2 1, {[n-Bu2SnO2C-CH2-S-C6H4]2O}2 2, and [Ph3SnO2C-(CH=CH)2-C7H5O2]n 3, have been characterized by IR, 1H and 13C NMR spectroscopic techniques. Single crystal diffraction studies were made to determine the structures of the three compounds 1, 2 and 3. Compounds 1 and 2 crystallize in the triclinic system (P\-1), and the respective cell parameters (Å, °) [a = 10.4427 (19), b = 12.881 (2), c= 15.991 (3), a= 76.840 (7), b= 85.130 (6), g= 87.278 (6), and [a = 12.237 (3),  b = 12.580 (3),  c= 13.507 (3), a= 91.146 (8),  b= 104.916 (8), g= 111.307 (8)]. Compound 3 crystallizes in the Monoclinic system (P21/c) with the cell parameters (Å, °) [a= 12.982 (3), b= 11.282 (2), c= 18.528 (4) and b (°) = 108.572 (7)]. The title compounds were evaluated for their biological activities against a range of cancer cell lines (BT-474, MDA-MB-231, AU565), Chronic myeloid leukemia cell line (K562), Lung cancer cell line (H460) and normal cell line 3T3 mouse fibroblast. Especially complexes 1 and 3 (derivatives of the piperic acid), i.e. Pipericcarboxylate triphenyltin [Ph3SnO2C-(CH=CH) 2-C7H5O2]n and {[n-Bu2SnO2C-(CH=CH)2-C7H5O2]2O}2 were most active against all cancer cell lines. These compounds were also active against 3T3 normal cell line, but the IC50 values were high as compared to cancer cell lines

Synthesis, crystal structure, physical and catalytic oxidation studies of a new hybrid phosphate [(N2H5)2Co(HPO4)2]

A new one-dimensional coordination polymer [(N2H5)2Co(HPO4)2] was synthesized by slow evaporation method and characterized by means of single-crystal X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). Its catalytic activity was tested using UV–visible absorption measurements. The compound crystallizes in the monoclinic system (S.G: P21/c) with the cell parameters (Å, °): a = 5.3665(3), b = 11.1271(6), c = 7.7017(4), β = 104.843(4), V = 444.55(4) Å3 and Z = 2. The crystal structure, consisting of a linear chain, is made of rings of [CoN2O4] octahedra and [PO3(OH)] tetrahedra sharing vertices via oxygen atoms coordinated to cobalt centers. The rings are linked to chains running along [100] and form thereby polymeric chains that are connected by hydrogen bonds in a three-dimensional arrangement. The FTIR spectroscopy shows the expected bands of hydrazine and phosphate groups. The thermal behavior consists mainly of the loss of hydrazine moieties leading thus to the formation of anhydrous cobalt phosphate. The phosphate complex exhibits efficiency in catalytic oxidation and degradation of methylene blue dye. The ac magnetic susceptibility shows a peak indicating antiferromagnetic order with a Néel temperature of 5.5 K. Fitting the Curie-Weiss equation to the ac magnetic susceptibility above 50 K gives the average Curie-Weiss Constant to be −11.8 K

Charmonium Spectrum from Quenched Anisotropic Lattice QCD

We present a detailed study of the charmonium spectrum using anisotropic lattice QCD. We first derive a tree-level improved clover quark action on the anisotropic lattice for arbitrary quark mass. The heavy quark mass dependences of the improvement coefficients, i.e. the ratio of the hopping parameters $\zeta=K_t/K_s$ and the clover coefficients $c_{s,t}$, are examined at the tree level. We then compute the charmonium spectrum in the quenched approximation employing $\xi = a_s/a_t = 3$ anisotropic lattices. Simulations are made with the standard anisotropic gauge action and the anisotropic clover quark action at four lattice spacings in the range $a_s$=0.07-0.2 fm. The clover coefficients $c_{s,t}$ are estimated from tree-level tadpole improvement. On the other hand, for the ratio of the hopping parameters $\zeta$, we adopt both the tree-level tadpole-improved value and a non-perturbative one. We calculate the spectrum of S- and P-states and their excitations. The results largely depend on the scale input even in the continuum limit, showing a quenching effect. When the lattice spacing is determined from the $1P-1S$ splitting, the deviation from the experimental value is estimated to be $\sim$30% for the S-state hyperfine splitting and $\sim$20% for the P-state fine structure. Our results are consistent with previous results at $\xi = 2$ obtained by Chen when the lattice spacing is determined from the Sommer scale $r_0$. We also address the problem with the hyperfine splitting that different choices of the clover coefficients lead to disagreeing results in the continuum limit.Comment: 43 pages, 49 eps figures, revtex; minor changes, version to appear in Physical Review

Comparative Study of full QCD Hadron Spectrum and Static Quark Potential with Improved Actions

We investigate effects of action improvement on the light hadron spectrum and the static quark potential in two-flavor QCD for $a^{-1} \approx 1$ GeV and $m_{PS}/m_V = 0.7-0.9$. We compare a renormalization group improved action with the plaquette action for gluons, and the SW-clover action with the Wilson action for quarks. We find a significant improvement in the hadron spectrum by improving the quark action, while the gluon improvement is crucial for a rotationally invariant static potential. We also explore the region of light quark masses corresponding to $m_{PS}/m_V \geq 0.4$ on a 2.7 fm lattice using the improved gauge and quark action. A flattening of the potential is not observed up to 2 fm.Comment: LaTeX, 35 pages, 22 eps figures, uses revtex and eps

Leptonic Decays of Heavy Quarks on the Lattice

The status of lattice calculations of heavy-light decay constants and of the $B$ parameter $B_B$ is reviewed. After describing the lattice approach to heavy quark systems, the main results are discussed, with special emphasis on the systematic errors in present lattice calculations. A detailed analysis of the continuum limit for decay constants is performed. The implications of lattice results on studies of CP violation in the Standard Model are discussed.Comment: Invited review to be published in Int. J. Mod. Phys. A, 63 pages, LaTeX, ijmpa1.sty (included), 8 postscript figure

Heavy-Light Mesons with Quenched Lattice NRQCD: Results on Decay Constants

We present a quenched lattice calculation of heavy-light meson decay constants, using non-relativistic (NRQCD) heavy quarks in the mass region of the $b$ quark and heavier, and clover-improved light quarks. The NRQCD Hamiltonian and the heavy-light current include the corrections at first order in the expansion in the inverse heavy quark mass. We study the dependence of the decay constants on the heavy meson mass $M$, for light quarks with the tree level ($c_{SW}$ = 1), as well as the tadpole improved clover coefficient. We compare decay constants from NRQCD with results from clover ($c_{SW}=1$) heavy quarks. Having calculated the current renormalisation constant $Z_A$ in one-loop perturbation theory, we demonstrate how the heavy mass dependence of the pseudoscalar decay constants changes after renormalisation. For the first time, we quote a result for $f_B$ from NRQCD including the full one-loop matching factors at $O(\alpha/M)$.Comment: 45 pages, latex, 24 postscript figure