inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 64| Part 6| June 2008| Pages i30-i31

Disodium zinc bis­­(sulfate) tetra­hydrate (zinc astrakanite) revisited

aUniversidad Nacional de la Patagonia, Sede Puerto Madryn, and CenPat, CONICET, 9120 Puerto Madryn, Chubut, Argentina, bDepartamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, and CIMAT, Casilla 487-3, Santiago de Chile, Chile, and cDepartamento de Física, Comisión Nacional de Energía Atómica, Buenos Aires, Argentina
*Correspondence e-mail: undiaz@cenpat.edu.ar

(Received 7 March 2008; accepted 8 April 2008; online 7 May 2008)

We present a new low-temperature refinement of disodium zinc bis­(sulfate) tetra­hydrate {systematic name: poly[tetra-μ-aqua-di-μ-sulfato-zinc(II)disodium(I)]}, [Na2Zn(SO4)2(H2O)4]n or Zn astrakanite, which is an upgrade of previously reported data [Bukin & Nozik (1974[Bukin, V. I. & Nozik, Yu. Z. (1974). Zh. Strukt. Khim. 15, 712-716.]). Zh. Strukt. Khim. 15, 712–716]. The compound is part of an isostructural family containing the Mg (the original astrakanite mineral), Co and Ni species. The very regular ZnO(aqua)4O(sulfate)2 octa­hedra lie on centres of symmetry, while the rather distorted NaO(aqua)2O(sulfate)4 octa­hedra appear at general positions, linked into a three-dimensional network by the bridging water mol­ecules and the fully coordinated sulfate groups.

Related literature

For related literature, see: Rumanova (1958[Rumanova, I. M. (1958). Dokl. Akad. Nauk SSSR, 118, 84-87.]); Giglio (1958[Giglio, M. (1958). Naturwissenschaften, 45, 82-83.]); Bukin & Nozik (1974[Bukin, V. I. & Nozik, Yu. Z. (1974). Zh. Strukt. Khim. 15, 712-716.], 1975[Bukin, V. I. & Nozik, Yu. Z. (1975). Kristallografiya, 20, 293-296.]); Díaz de Vivar et al. (2006[Díaz de Vivar, M. E. de, Baggio, S., Garland, M. T. & Baggio, R. (2006). Acta Cryst. E62, i196-i198.]).

[Scheme 1]

Experimental

Crystal data
  • [Na2Zn(SO4)2(H2O)4]

  • Mr = 375.53

  • Monoclinic, P 21 /c

  • a = 5.5075 (2) Å

  • b = 8.2127 (3) Å

  • c = 11.0559 (4) Å

  • β = 99.958 (10)°

  • V = 492.54 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 3.07 mm−1

  • T = 170 (2) K

  • 0.30 × 0.20 × 0.10 mm

Data collection
  • Bruker SMART CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.452, Tmax = 0.728

  • 3533 measured reflections

  • 1080 independent reflections

  • 1062 reflections with I > 2σ(I)

  • Rint = 0.012

Refinement
  • R[F2 > 2σ(F2)] = 0.017

  • wR(F2) = 0.054

  • S = 1.00

  • 1080 reflections

  • 96 parameters

  • 6 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.29 e Å−3

  • Δρmin = −0.53 e Å−3

Table 1
Selected bond lengths (Å)

Zn1—O1W 2.0636 (11)
Zn1—O3 2.0952 (11)
Zn1—O2W 2.1285 (11)
Na1—O2i 2.3603 (12)
Na1—O4ii 2.3786 (12)
Na1—O1 2.4016 (12)
Na1—O1W 2.4017 (12)
Na1—O2iii 2.4224 (13)
Na1—O2Wiv 2.5694 (13)
Symmetry codes: (i) [x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (ii) [-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iii) [-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iv) [-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}].

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1W—H1WA⋯O1iii 0.800 (17) 1.916 (17) 2.6977 (17) 165 (3)
O1W—H1WB⋯O4v 0.832 (16) 1.901 (16) 2.7288 (17) 173 (2)
O2W—H2WA⋯O1ii 0.826 (16) 2.051 (18) 2.8468 (16) 162 (2)
O2W—H2WB⋯O4vi 0.805 (16) 2.15 (2) 2.8779 (16) 151 (3)
Symmetry codes: (ii) [-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iii) [-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]; (v) x-1, y, z; (vi) -x+1, -y, -z.

Data collection: SMART (Bruker, 2001[Bruker (2001). SMART and SAINT for Windows NT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2001[Bruker (2001). SMART and SAINT for Windows NT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]).

Supporting information


Comment top

The original mineral astrakanite [Na2M(SO4)2(H2O)4], M = Mg, structurally characterized almost 50 years ago (Rumanova, 1958), gave its name to a whole isostructural family, of which some members have been known for a long while (M = Zn, Giglio, 1958; Bukin & Nozik, 1974; M = Co, Bukin & Nozik, 1975), while the Ni analogue has been only recently reported, (Díaz de Vivar et al., 2006). We present herein an improved, low temperature data refinement of the zinc member of the group, Na2Zn(SO4)2(H2O)4 (I), unwittingly obtained as a byproduct while looking for something else (See experimental section).

Fig. 1 shows the asymmetric unit of (I) as well as part of its close environment, and Table 1 presents some selected bond distances. The structure consists of ZnO(aqua)4O(sulf)2 and NaO(aqua)2O(sulf)4 octahedra in a 1:2 ratio, linked through two bridging water molecules (O1W, O2W) and the fully coordinated sulfato groups.

Zn cations lay on centers of symmetry and their coordination polyhedra defined by O3, O1w, O2w and their respective centrosymmetric counterparts are quite regular, possibly due to the large number of geometrically unconstrained aqua molecules (Parameters range: Zn—O,2.0636 (11)–2.1285 (11) Å; (O—Zn—O)cis, 87.38 (5)–92.62 (5)°; (O—Zn—O)trans, 180.°, fixed by symmetry). Na cations, instead, occupy general positions and, contrasting the former, their O(sulf)-rich coordination octahedra appear as quite irregular (Parameters range: Na—O,2.3603 (12)–2.5694 (13) Å; (O—Na—O)cis, 74.93 (4)–112.94 (4)°; (O—Na—O)trans, 155.87 (5)–162.11 (5)°).

The geometry of the sulfate anion is rather regular, with S—O distances in the range 1.4619 (11) to 1.4878 (11) Å and angles from 107.38 (5) to 110.89 (7)°. The group exhibits a complex µ5-κ4-O:O':O'':O''' coordination, binding in a monocoordinated fashion to Zn through O3 and to Na through O1 and O4, while bridging two Na cations through O2. The result of this intricate interconnectivity is the formation of broad two-dimensional structures parallel to (100) containing both types of polyhedra (Fig.1) and internally linked by the two bridging aqua and O atoms O1, O2 and O3 from the sulfate anion.

These "planes", in turn, are interconnected along a single "strong" interaction, the O4—Na1 bonds between sulfate O4 atoms from a given layer and Na1 cations from their neighbours (Fig. 2).

Also H-bonding interactions (Table 2) contribute to the intraplane (via O1W, entries 1 and 2) and interplane (via O2W, entries 3 and 4) cohesion.

It is worth noting that O1 and O4 act as the only (double) acceptors for H-bonding. In analyzing the S—O bond lengths, it appears that S1—O1 and S1—O4 present precisely the longest distances suggesting a slight weakening effect on the S—O covalent link due to the oxygen involvement in H interactions.

Even though the isostructural character of (I) with the rest of the strakanite family is obvious by inspection, the low precision with which the Mn and Co members have been reported leaves comparison with the Ni moiety as the only relevant one. In this respect, both structures are almost undistinguishable, as proved by the least squares fit of the extended group shown in Fig. 3, where the maximum departure amounts for less than 0.05Å for atom O2W.

Related literature top

For related literature, see: Rumanova (1958); Giglio (1958); Bukin & Nozik (1974, 1975); Díaz de Vivar et al. (2006).

Experimental top

The compound was obtained an an unintended product in a synthesis of Zn(II) complexes. Recently prepared anysaldehyde bisulfitic derivative (60 mg) were dissolved in 5 ml of water and mixed with an aqueous solution of Zn acetate (112 mg/5 ml). The aqueous mixture was left in a methanol atmosphere, until colourless cubic crystals were obtained.

Refinement top

Hydrogen atoms pertaining to water molecules were found in the difference- Fourier synthesis and refined with restrained O—H:0.82 (2) Å, H···H:1.35 (2) Å, but free isotropic displacement parameters.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. A (100) view of the structure with the independent atoms drawn in full 50% displacemenet ellipsoids and full bonds. The symmetry related part, in open ellipsoids and hollow bonds. Hydrogen interactions drawn in broken lines. Symmetry codes: (i) x, -y + 1/2, z + 1/2; (ii) -x + 1, y - 1/2, -z + 1/2; (iii) -x, y - 1/2, -z + 1/2; (iv) -x, y + 1/2, -z + 1/2. (v) x - 1, y, z; (vi) -x + 1, -y, -z; (vii) -x, -y, -z.
[Figure 2] Fig. 2. Packing view down the <010> direction showing a side view of the planar structures, and the way they interact through the O4—Na1 bonds along [100]. H-bonds omited in this view, for clarity.
[Figure 3] Fig. 3. Least squares fit of an extended atomic group in (I), in full lining, and its Ni counterpart (Díaz de Vivar et al., 2006), in dashed lining. Note the almost perfect overlap of both structures.
poly[tetra-µ-aqua-di-µ–sulfato-zinc(II)disodium(I)] top
Crystal data top
[Na2Zn(SO4)2(H2O)4]F(000) = 376
Mr = 375.53Dx = 2.539 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3942 reflections
a = 5.5075 (2) Åθ = 3.8–26.7°
b = 8.2127 (3) ŵ = 3.07 mm1
c = 11.0559 (4) ÅT = 170 K
β = 99.958 (1)°Prism, colourless
V = 492.54 (3) Å30.30 × 0.20 × 0.10 mm
Z = 2
Data collection top
Bruker SMART CCD
diffractometer
1080 independent reflections
Radiation source: fine-focus sealed tube1062 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.012
ϕ and ω scansθmax = 27.9°, θmin = 3.1°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 67
Tmin = 0.452, Tmax = 0.728k = 1010
3533 measured reflectionsl = 1314
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.017H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.054 w = 1/[σ2(Fo2) + (0.0408P)2 + 0.265P]
where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
1080 reflectionsΔρmax = 0.29 e Å3
96 parametersΔρmin = 0.53 e Å3
6 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.080 (4)
Crystal data top
[Na2Zn(SO4)2(H2O)4]V = 492.54 (3) Å3
Mr = 375.53Z = 2
Monoclinic, P21/cMo Kα radiation
a = 5.5075 (2) ŵ = 3.07 mm1
b = 8.2127 (3) ÅT = 170 K
c = 11.0559 (4) Å0.30 × 0.20 × 0.10 mm
β = 99.958 (1)°
Data collection top
Bruker SMART CCD
diffractometer
1080 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
1062 reflections with I > 2σ(I)
Tmin = 0.452, Tmax = 0.728Rint = 0.012
3533 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0176 restraints
wR(F2) = 0.054H atoms treated by a mixture of independent and constrained refinement
S = 1.00Δρmax = 0.29 e Å3
1080 reflectionsΔρmin = 0.53 e Å3
96 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Zn10.00000.00000.00000.00887 (13)
Na10.12607 (11)0.07173 (8)0.36217 (5)0.01231 (17)
S10.37405 (6)0.28842 (4)0.13609 (3)0.00821 (14)
O10.3516 (2)0.27120 (14)0.26765 (10)0.0127 (2)
O20.2085 (2)0.41630 (14)0.07871 (10)0.0136 (3)
O30.3186 (2)0.13129 (14)0.07174 (10)0.0134 (2)
O40.63500 (19)0.32955 (13)0.13056 (10)0.0127 (2)
O1W0.1247 (2)0.03807 (16)0.16331 (10)0.0110 (2)
O2W0.1753 (2)0.21442 (13)0.08065 (10)0.0115 (2)
H1WA0.215 (5)0.032 (3)0.179 (2)0.028 (7)*
H1WB0.207 (4)0.123 (2)0.156 (2)0.023 (6)*
H2WA0.299 (4)0.203 (3)0.1341 (18)0.021 (6)*
H2WB0.213 (5)0.278 (3)0.032 (2)0.034 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.01021 (18)0.00753 (17)0.00909 (17)0.00024 (7)0.00231 (11)0.00054 (7)
Na10.0133 (3)0.0116 (3)0.0118 (3)0.0002 (2)0.0015 (2)0.0005 (2)
S10.0083 (2)0.0075 (2)0.0089 (2)0.00016 (12)0.00150 (13)0.00049 (12)
O10.0156 (6)0.0130 (5)0.0101 (5)0.0014 (4)0.0034 (4)0.0013 (4)
O20.0149 (5)0.0139 (6)0.0119 (5)0.0051 (4)0.0017 (4)0.0017 (4)
O30.0111 (5)0.0109 (5)0.0179 (5)0.0016 (4)0.0022 (4)0.0054 (4)
O40.0103 (5)0.0110 (5)0.0176 (5)0.0021 (4)0.0042 (4)0.0016 (4)
O1W0.0114 (5)0.0098 (5)0.0122 (5)0.0000 (4)0.0035 (4)0.0002 (4)
O2W0.0120 (5)0.0100 (5)0.0118 (5)0.0007 (4)0.0002 (4)0.0017 (4)
Geometric parameters (Å, º) top
Zn1—O1Wi2.0636 (11)Na1—O2Wv2.5694 (13)
Zn1—O1W2.0636 (11)Na1—Na1vi3.7507 (12)
Zn1—O32.0952 (11)S1—O21.4619 (11)
Zn1—O3i2.0952 (11)S1—O31.4797 (11)
Zn1—O2W2.1285 (11)S1—O11.4876 (11)
Zn1—O2Wi2.1285 (11)S1—O41.4878 (11)
Na1—O2ii2.3603 (12)O1W—H1WA0.800 (17)
Na1—O4iii2.3786 (12)O1W—H1WB0.832 (16)
Na1—O12.4016 (12)O2W—H2WA0.826 (16)
Na1—O1W2.4017 (12)O2W—H2WB0.805 (16)
Na1—O2iv2.4224 (13)
O1Wi—Zn1—O1W180.00 (9)O1—Na1—O2Wv92.61 (4)
O1Wi—Zn1—O391.46 (4)O1W—Na1—O2Wv90.58 (4)
O1W—Zn1—O388.54 (4)O2iv—Na1—O2Wv74.93 (4)
O1Wi—Zn1—O3i88.54 (4)O2—S1—O3110.89 (7)
O1W—Zn1—O3i91.46 (4)O2—S1—O1109.97 (6)
O3—Zn1—O3i180.00 (8)O3—S1—O1110.00 (7)
O1Wi—Zn1—O2W92.62 (5)O2—S1—O4110.71 (7)
O1W—Zn1—O2W87.38 (5)O3—S1—O4107.38 (6)
O3—Zn1—O2W88.72 (4)O1—S1—O4107.81 (7)
O3i—Zn1—O2W91.28 (4)S1—O1—Na1128.83 (7)
O1Wi—Zn1—O2Wi87.38 (5)S1—O2—Na1vii117.79 (6)
O1W—Zn1—O2Wi92.62 (5)S1—O2—Na1v135.07 (7)
O3—Zn1—O2Wi91.28 (4)Na1vii—O2—Na1v103.29 (4)
O3i—Zn1—O2Wi88.72 (4)S1—O3—Zn1136.09 (7)
O2W—Zn1—O2Wi180.00 (7)S1—O4—Na1viii136.15 (7)
O2ii—Na1—O4iii89.56 (4)Zn1—O1W—Na1126.34 (5)
O2ii—Na1—O1112.94 (4)Zn1—O1W—H1WA113 (2)
O4iii—Na1—O1105.09 (4)Na1—O1W—H1WA99.6 (19)
O2ii—Na1—O1W155.87 (5)Zn1—O1W—H1WB107.7 (17)
O4iii—Na1—O1W99.32 (5)Na1—O1W—H1WB102.0 (17)
O1—Na1—O1W86.50 (4)H1WA—O1W—H1WB106 (2)
O2ii—Na1—O2iv76.71 (4)Zn1—O2W—Na1iv113.77 (5)
O4iii—Na1—O2iv89.57 (4)Zn1—O2W—H2WA117.7 (16)
O1—Na1—O2iv162.11 (5)Na1iv—O2W—H2WA112.8 (17)
O1W—Na1—O2iv80.94 (4)Zn1—O2W—H2WB114.1 (18)
O2ii—Na1—O2Wv75.00 (4)Na1iv—O2W—H2WB89 (2)
O4iii—Na1—O2Wv160.12 (5)H2WA—O2W—H2WB106 (2)
Symmetry codes: (i) x, y, z; (ii) x, y+1/2, z+1/2; (iii) x+1, y1/2, z+1/2; (iv) x, y1/2, z+1/2; (v) x, y+1/2, z+1/2; (vi) x, y, z+1; (vii) x, y+1/2, z1/2; (viii) x+1, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WA···O1iv0.80 (2)1.92 (2)2.6977 (17)165 (3)
O1W—H1WB···O4ix0.83 (2)1.90 (2)2.7288 (17)173 (2)
O2W—H2WA···O1iii0.83 (2)2.05 (2)2.8468 (16)162 (2)
O2W—H2WB···O4x0.81 (2)2.15 (2)2.8779 (16)151 (3)
Symmetry codes: (iii) x+1, y1/2, z+1/2; (iv) x, y1/2, z+1/2; (ix) x1, y, z; (x) x+1, y, z.

Experimental details

Crystal data
Chemical formula[Na2Zn(SO4)2(H2O)4]
Mr375.53
Crystal system, space groupMonoclinic, P21/c
Temperature (K)170
a, b, c (Å)5.5075 (2), 8.2127 (3), 11.0559 (4)
β (°) 99.958 (1)
V3)492.54 (3)
Z2
Radiation typeMo Kα
µ (mm1)3.07
Crystal size (mm)0.30 × 0.20 × 0.10
Data collection
DiffractometerBruker SMART CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.452, 0.728
No. of measured, independent and
observed [I > 2σ(I)] reflections
3533, 1080, 1062
Rint0.012
(sin θ/λ)max1)0.658
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.017, 0.054, 1.00
No. of reflections1080
No. of parameters96
No. of restraints6
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.29, 0.53

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Selected bond lengths (Å) top
Zn1—O1W2.0636 (11)Na1—O12.4016 (12)
Zn1—O32.0952 (11)Na1—O1W2.4017 (12)
Zn1—O2W2.1285 (11)Na1—O2iii2.4224 (13)
Na1—O2i2.3603 (12)Na1—O2Wiv2.5694 (13)
Na1—O4ii2.3786 (12)
Symmetry codes: (i) x, y+1/2, z+1/2; (ii) x+1, y1/2, z+1/2; (iii) x, y1/2, z+1/2; (iv) x, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WA···O1iii0.800 (17)1.916 (17)2.6977 (17)165 (3)
O1W—H1WB···O4v0.832 (16)1.901 (16)2.7288 (17)173 (2)
O2W—H2WA···O1ii0.826 (16)2.051 (18)2.8468 (16)162 (2)
O2W—H2WB···O4vi0.805 (16)2.15 (2)2.8779 (16)151 (3)
Symmetry codes: (ii) x+1, y1/2, z+1/2; (iii) x, y1/2, z+1/2; (v) x1, y, z; (vi) x+1, y, z.
 

Acknowledgements

The authors acknowledge the Spanish Research Council (CSIC) for providing a free-of-charge licence to the Cambridge Structural Database (Allen, 2002[Allen, F. H. (2002). Acta Cryst. B58, 380-388.]).

References

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ISSN: 2056-9890
Volume 64| Part 6| June 2008| Pages i30-i31
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