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Cape porcupines ( Hystrix africaeaustralis ) appear to have an important influence on landscapes through both biotic (foraging) and abiotic (soil turnover) impacts. Porcupine abundance and abiotic effects across the landscape were investigated in Nieuwoudtville, South Africa, a semi-arid area characterized by an extraordinary diversity and abundance of geophytes. Porcupine numbers were measured in 50 burrows, and the number of burrow entrances was a good predictor of the number of porcupines it contained ( r 2 =0.76). Occupied burrow density was estimated to be 2.6 burrows km −2 and porcupine density on the study farm was estimated to be 8 animals km −2 , which is high relative to other Hystrix populations in semi-arid environments. This can probably be attributed to the high abundance of geophytes in the region. Annually, porcupines disturb 0.34% of the soil surface and 1.6 m 3 ha −1 yr −1 of soil is displaced across the landscape, through the excavation of 160–3463 diggings per hectare. Up to 2.2 m 3 of soil is displaced per hectare per year in the natural Dolerite Plains vegetation, but very little foraging activity occurs in previously or currently ploughed lands. The extent of disturbance in Nieuwoudtville is on a par with or higher than that recorded for other porcupine populations in arid or semi-arid regions. Other studies have shown that porcupine diggings disturb plant community structure and create fertile sites for plant germination and recruitment. Porcupine diggings in Nieuwoudtville contained significantly more seedlings than adjacent areas. Thus, through widespread foraging pits, soil turnover, and numerous burrows, porcupines modulate the availability of resources to other organisms. Therefore, Cape porcupines are likely to act as ecosystem engineers in this landscape. Porcupines should be included in any conservation actions involving the unique geophyte flora of Nieuwoudtville.

Life cycle assessments on electronic components is still a relatively new and complex process. Much of the data required for the analysis do not exist. The manufacturing processes involved demand that considerable effort and resources are input to complete a LCA. The LCA of the telecommunications semiconductor laser has shown that it is possible to model part of the product's life and produce results that are usable.

the use of prostaglandians in maintaining the patency of the arterial duct in congenital heart disease is well established. Intravenous1-3 and ora12–4 administration has been used, although for acute use intravenous and possibly intraosseous5 routes are favored. Both prostaglandin E1 (alprostadil—ProstinVR: Upjohn)1,4 and prostaglandin E2 (dinoprostone—Prostin E2: Upjohn)2,3 are used for this purpose, although only prostaglandin E1 is licensed for this indication in the United Kingdom. Prostaglandin E1 costs approximately 8 times more than prostaglandin E2 (£56.96 versus £7.43 per vial).

The i.r. and Raman spectra of tetragonal (red) and PbO and orthorhombic (yellow) PbO have been obtained. Frequencies, in good agreement with those observed, have been calculated using the Wilson FG matrix method. In both forms of PbO, it was found necessary to include metal-metal interactions in order to obtain such agreement. The absence of coincidences between the i.r. and Raman spectra of yellow PbO support the conclusion, reached by neutron deffraction studies, that, the space group of yellow PbO is the centrosymmetric D 2 h 11 ( Pbcm ); thus this material cannot be ferroelectric, as has previously been suggested.

The products obtained from molten and aqueous SnF 2 : M I systems ( M = Na, K, Rb, and NH 4 ) have been studied. The Mossbauer data for phases with 1:1, 2:1, and 3:1 SnF 2 : M I molar ratios are reported. The M SnIF 2 phases show evidence of two tin sites, one of which has Mossbauer parameters attributable to an octahedral tin(II) environment. The materials obtained are all colored and the reasons for these colors are discussed.

A series of compounds, Cs3MIII2X9 (MIII = Sb and Bi, X = Cl or Br) are doped with impurity ions (Ba2+, Ca2+, Sn2+, Pb2+, Mg2+, Fe2+, Tl3+, In3+, Se4+). Lattices doped with Sn(II), Pb(II) and Se(IV) are colored. Sn-119m Mossbauer data are consistent with the donation of Sn-5s electron density from tin(II) to a conduction band to give a pseudo-tin(IV) electronic environment.

Phases in the spinel series Zn2+[Zn (1−x) 2 2+Sn 1+x 2 Fe1−x3+Fex2+]O4 have been prepared and studied by 57Fe and 119Sn Mossbauer spectroscopy. For 0 ⩽ x ⩽ 0.75 the spinels remain paramagnetic down to 80 K. Evidence is found for fast localized electron hopping between adjacent Fe2+ and Fe3+ ions and also for the complete delocalization of electrons into a conduction band. A model which quantitatively accounts for this latter phenomenon is presented.

The electronic structure of the cubic phase of crystalline CsSnBr 3 has been investigated using X-ray photoelectron spectroscopy and a semiempirical energy band structure calculation. The observed semimetallic behaviour of this system and some similar crystalline trihalides in the cubic phase is related to the presence of a triply degenerate R 15 energy level in the calculated conduction band. The nonmetallic behaviour of the cubic phase of CsSnCl 3 may be accounted for by consideration of the spin-orbit splitting of this R 15 level.

Mossbauer spectroscopic evidence for the loss of s-electron density from the 5s2 species Sn(II) and Sb(III) to solid-state bands is presented. Results of Sn-119 studies on phases based on Cs4SnBr6, of Sn-119 studies at high temperatures using Sn-119 enriched CsSnBr3 and Sb-121 studies on (C5H5NH)6 SbIIISb3VBr24 and of phases based on Cs3Sb2Cl9 are discussed. Te-125 evidence for the possible electron acceptor ability of approximately close-packed telluride lattices is also evaluated.

The effect is studied of the presence of a wax binder on the flammability of, and smoke production from, systems containing acrylonitrile-butadiene-styrene copolymer, decabromobiphenyl and (a) antimony(III) oxide and (b) metastannic acid. The studies were carried out both by linear and by triangular designs and values were measured of flammability (by limiting oxygen index) and of smoke production (by maximum smoke density). Pelletisation of the additive metal compound or the addition of up to 3 phr of wax has virtually no effect on the properties of the system. It is thus shown that the use of up to 3 phr of a wax binder can reduce the health hazard arising from the use of powdered flame-retarding and smoke-suppressing additives.

The infra-red spectra of phases with the compositions Cs2Sn2(Cl6—nBrn) have been obtained. The spectra of CsSnCl3 (in its high temperature form) and CsSnBr3 are consistent with the perovskite structure which these materials have. The spectra of the phases of intermediate composition show “ordered” behaviour of the highest frequency mode, “continuous” behaviour of the second highest frequency mode, and virtual constancy of the lowest frequency mode. These results are interpreted with the aid of force constant calculations employing a valence force field.

Flame retardance and smoke suppression have been studied in three systems containing acrylonitrile-butadiene-styrene terpolymer, decabromobiphenyl, and (a) commercial metastannic acid, (b) laboratory-prepared metastannic acid and (c) anhydrous tin(IV) oxide. Values of limiting oxygen index and smoke density have been measured for a large number of compositions in each system. They have then been fitted by fourth-order polynomials and plotted in triangular diagrams. Optimum atomic ratios for all these synergistic systems were found to be: Br/Sn = 9, a value which is much higher than would be expected from stoichiometric calculations. The systems also possess significant smoke-suppressant effectiveness.

In December 1986 a 30-month-old female child with morbid obesity and respiratory failure was admitted to the Izaak Walton Killam Hospital for Children in Halifax. The etiology of the obesity was found to be dietary in origin after rulling out genetic, neurological and metabolic causes. This patient exhibited somnolence and cyanosis in association with hypercapnia and right ventricular overload. Her respiratory failure in the presence of a normal upper airway required ventilatory support, first with nasal endotracheal intubation, and then, tracheotomy. Weight reduction normalized her capillary blood gases and her somnolence disappeared. Subglottic stenosis hampered removal of the tracheotomy tube until 9 months after admission. The pathogenesis and management of obese hypoventilation syndrome are reviewed by the authors.

Four planar tellurium(II) complexes with thiourea type ligands have been characterized. Crystal structures for two of the complexes are reported. Te(tu)4(ClO4)2), |tu = thiourea| is triclinic, space group P 1 , a = 15.35, b = 11.97 c = 6.01 A, α = 90.1 β = 91.0, γ = 108.0° and Z = 2; Te(dmtu)4Cl2 |dmtu = 1,3-dimethylthiourea| is monoclinic, space group P21/n, a = 13.70, b = 9.05, c = 10.91 A,β = 101.6° and Z = 2. In both the complexes the tellurium is bonded to four sulphur atoms in a planar arrangement which is considerably distorted in the perchlorate but nearly regular in the chloride. In order to explain the structural and 125Te Mossbauer spectroscopy results, a bonding model involving lone-pairs with s- and p- character is proposed.

The preparation of a new orthorhombic form of hydrated holmium and dysposium phosphate is described. X-Ray powder data is consistent with an orthorhombic cell whose space group is P 222 (D 2 1 ); the cell dimensions were calculated and are in good agreement with the measured density, for Z =8. If the eight P atoms occupy the eight 222 sites ( a−h ), both the spectroscopic and crystallographic requirements are met.

Chromatographic separations of transition metal (II) ions among themselves and from alkaline earth and transition metal (III) species on hydrous tin (IV) oxide columns are described.

The nature of the tin-cobalt bond in the series of compounds of formula [Co(CO)3L]xSnX4-x, (L =CO, PPh3 or PBun3; X = Cl, Br, I, Et, or Ph; x = 1 or 2) was studied by means of the 119m Sn Mossbauer effect. The results in the present work extend the information obtained for the related tin-manganese complexes previously studied.

The sorption of alkali and alkaline earth cations on hydrous tin(IV) oxide has been investigated, in particular on the exchanger in the NH4+ form, and some chromatographic separations among these ions are described. The use of the exchanger in the H+ form to remove UO2(II) and transition metal ion contamination from solutions containing large amounts of the above ions has also been investigated. Some anion-exchange properties of this material are reported, and the marked selectivity series established predicts the possibility of facile separations of certain anionic species on columns of hydrous SnO2.

The infra-red spectra of seven pentafluorodistannates (II) have been measured as Nujol mulls from 667-250 cm −1 and as Rigidex disks from 500-60 cm −1 . A normal co-ordinate analysis of the Sn 2 F 5 − ion with C 2 symmetry has been performed, using a general valence force field, and the vibrations assigned.

The infra-red spectra of twenty formates have been measured as mulls in Nujol and hexachlorobutadiene. The influence of the metal ion on the carboxylate stretching frequencies has been investigated, and possible correlations between spectra and structure considered.

The ion-exchange properties of granular tin(IV) phosphate and arsenate gels, prepared under similar experimental conditions, have been compared and contrasted. Both materials behave as polyfunctional cation exchangers, and the arsenate offers no advantage over the better-established phosphate either in ion-exchange capacity or base stability. Both materials exhibit marked selectivities within the alkali metal, alkaline earth, and transition metal(II) groups of ions, although they do not show the same marked inter-group selectivity as does hydrous SnO2.

The spectra of twenty-one such complexes were recorded in the region 450-40 cm −1 and the skeletal vibrations assigned. The spectra indicate a distorted pyramidal structure for the tin-oxygen skeleton.

The coloured complexes produced in the systems Pd(II): Sn(II):X:X', where X and X' are different halide ions, have been studied. In bromide/iodide mixtures, palladium(II) reacts with tin(II) species in acidic ethanol media to form a deep purple complex with maximum absorption at 555 nm. This is the basis of a rapid and sensitive spectrophotometric method for the determination of palladium. The complex is stable in the absence of air, but water interferes and must not be present in amounts more than 15% of the total volume of the ethanolic mixture

The preparation of hydrous tin(IV) oxide in a suitable form for use as an ion exchanger is described. The evidence of X-ray, Mossbauer and differential thermal analysis data suggests that the exchange material is simply “wet” tin(IV) oxide and that the oxide is simply a host for adsorbed water, which itself must act as the exchanger. The cation exchange properties of the hydrous oxide both as a precipitate and a dried gel have been investigated and compared. High distribution coefficients and apparent capacities have been obtained, a selectivity series Cu(II) > Zn(II) > Co(II) ≥ Fe(II) > Ni(II) > Mn(II) is established, and the dried material shows good stability towards strong solutions of HNO3 and H2SO4.

The preparation, characterisation and thermal decomposition of the new material tin(II) perchlorate trihydrate is described. Its infra-red spectrum and Mossbauer parameters are reported and compared with the data for other metal perchlorates and tin(II) compounds.

The infra-red spectra of four tin (II) formate and five tin (II) acetate complexes have been measured as mulls in Nujol and hexachlorobutadiene. These spectra show the complexes to be unidentate.

The spectra of ten trifluorostannates (II) and nine tricarboxylato-stannates (II) have been measured as Nujol mulls in the region 660-220 cm −1 . The observed bands have been assigned to modes involving skeletal stretching. A normal co-ordinate analysis was made in order to determine the effect due to distortion of the regular pyramidal structure.

The infra-red spectra of five acetates and five deuterated acetates have been recorded as mulls in Nujol and hexachlorobutadiene. The influence of the metal on the carboxylate stretching frequencies has been studied, and the shift in the asymmetric stretching frequency related to the magnitude of the lone pair effect.