title: Isopolyoxometalates of Antimony: Arylstibonic Acids [H₈ (RSb)₁₂O₂₈] and Derived Dodecanuclear Polyoxostibonates [M₂H10−x(RSb)₁₂O₃₀]x−, M = Na or K

authors: Nicholson, Brian K.

subjects: chemistry

abstract: Electrospray ionization mass spectrometry shows arylstibonic acids, p-XC₆H₄SbO₃H₂ (X = methyl, nitro, or chloro), and 1-naphthylstibonic acid exist in MeCN as dodecanuclear aggregates [H₈(RSb)₁₂O₂₈]. With KOH or NaOH these form polyoxometalate ions [M₂H₈(RSb)₁₂O₃₀]²⁻ (M = K or Na) with a hexagonal antiprismatic array of the Sb atoms, as shown by X-ray crystallographic structures for three new examples. There is one firmly encapsulated 10-coordinate M⁺ ion within an inorganic 12-crown-6 moiety {Sb₆O₆} in the hexagonal channel and one six-coordinate M⁺.

text: Isopolyoxometalates of Antimony: Arylstibonic Acids [H₈ (RSb)₁₂O₂₈] and Derived Dodecanuclear Polyoxostibonates [M₂H10−x(RSb)₁₂O₃₀]x−, M = Na or K Electrospray ionization mass spectrometry shows arylstibonic acids, p-XC₆H₄SbO₃H₂ (X = methyl, nitro, or chloro), and 1-naphthylstibonic acid exist in MeCN as dodecanuclear aggregates [H₈(RSb)₁₂O₂₈]. With KOH or NaOH these form polyoxometalate ions [M₂H₈(RSb)₁₂O₃₀]²⁻ (M = K or Na) with a hexagonal antiprismatic array of the Sb atoms, as shown by X-ray crystallographic structures for three new examples. There is one firmly encapsulated 10-coordinate M⁺ ion within an inorganic 12-crown-6 moiety {Sb₆O₆} in the hexagonal channel and one six-coordinate M⁺.

year: 2010

title: Secondary Blooming and Mottling in an Intravaginal Drug Release Product

authors: Waugh, Brendan Arthur

subjects: progesterone

abstract: This study was undertaken to determine the root cause of secondary blooming (surface progesterone) and mottling (translucent regions) in the CIDR insert.

A stability study on CIDR inserts found that the alternative supplier silicone (Dow Corning silicone is used in normal manufacture) did not exhibit either secondary blooming or mottling, in agreement with previous work. There was no difference in ‘in vitro’ drug release rate between CIDR inserts made from the two silicone feedstocks. This silicone was found to have a higher ratio of low molecular weight cyclic silicone compounds to straight chain silicone compounds (Measured through detected ion ratios in the leachate by ESMS). The exact relationship between blooming and secondary mottling and this discovery remains unknown.

Results from this research found that part B of the Dow Corning silicone was not responsible for causing secondary blooming and mottling in contrast to previous research. ESMS and GCMS results found that the Dow Corning part B had a more complex composition than of the samples from Dow Corning part A and alternative supplier silicone part A and part B.

It was found that addition of a silicone crosslinker into the Dow Corning silicone, increased mottling, but not secondary blooming. Increasing the mixing of progesterone and liquid silicone decreased mottling (via a static mixer), but did not increase surface progesterone.

The results from two studies into the packing of CIDR inserts immediately after manufacture were contradictory as one found a decrease in mottling from packing in line, while the other found no change in mottling. However there was no difference observed in surface progesterone levels between the packing conditions. Studies on the length of cure were also found to have no predictable effect on mottling.

Studies on arresting the cooling cured silicone above, between and below the melting points of the α and β progesterone polymorphs found that pausing cooling after cure at ~135 °C resulted in decreased secondary blooming and mottling, and that pausing after cure at ~125 °C exhibited less secondary blooming. Neither DSC nor XRD was able to determine a polymorphic bias in progesterone cooled by this cooling process (β progesterone polymorph was in all but one case (that had an added reduction in normal cooling rate)). Studies (XRD and DSC) on the cooling rate of progesterone found that only with very slow cooling rates was the α progesterone polymorph formed. XRD studies also revealed that the mottled regions of CIDR inserts exhibit the β progesterone polymorph, whereas the α progesterone polymorph was detected in non-mottled regions. The mottled regions were found to continue to exhibit the same polymorph after removal of surface progesterone, whereas the non-mottled regions gave no detectable XRD peak intensity.

The study found useful information to assist in the determination of the root cause of secondary blooming and mottling in CIDR inserts. However the root cause remains unknown.

text: Secondary Blooming and Mottling in an Intravaginal Drug Release Product This study was undertaken to determine the root cause of secondary blooming (surface progesterone) and mottling (translucent regions) in the CIDR insert.

A stability study on CIDR inserts found that the alternative supplier silicone (Dow Corning silicone is used in normal manufacture) did not exhibit either secondary blooming or mottling, in agreement with previous work. There was no difference in ‘in vitro’ drug release rate between CIDR inserts made from the two silicone feedstocks. This silicone was found to have a higher ratio of low molecular weight cyclic silicone compounds to straight chain silicone compounds (Measured through detected ion ratios in the leachate by ESMS). The exact relationship between blooming and secondary mottling and this discovery remains unknown.

Results from this research found that part B of the Dow Corning silicone was not responsible for causing secondary blooming and mottling in contrast to previous research. ESMS and GCMS results found that the Dow Corning part B had a more complex composition than of the samples from Dow Corning part A and alternative supplier silicone part A and part B.

It was found that addition of a silicone crosslinker into the Dow Corning silicone, increased mottling, but not secondary blooming. Increasing the mixing of progesterone and liquid silicone decreased mottling (via a static mixer), but did not increase surface progesterone.

The results from two studies into the packing of CIDR inserts immediately after manufacture were contradictory as one found a decrease in mottling from packing in line, while the other found no change in mottling. However there was no difference observed in surface progesterone levels between the packing conditions. Studies on the length of cure were also found to have no predictable effect on mottling.

Studies on arresting the cooling cured silicone above, between and below the melting points of the α and β progesterone polymorphs found that pausing cooling after cure at ~135 °C resulted in decreased secondary blooming and mottling, and that pausing after cure at ~125 °C exhibited less secondary blooming. Neither DSC nor XRD was able to determine a polymorphic bias in progesterone cooled by this cooling process (β progesterone polymorph was in all but one case (that had an added reduction in normal cooling rate)). Studies (XRD and DSC) on the cooling rate of progesterone found that only with very slow cooling rates was the α progesterone polymorph formed. XRD studies also revealed that the mottled regions of CIDR inserts exhibit the β progesterone polymorph, whereas the α progesterone polymorph was detected in non-mottled regions. The mottled regions were found to continue to exhibit the same polymorph after removal of surface progesterone, whereas the non-mottled regions gave no detectable XRD peak intensity.

The study found useful information to assist in the determination of the root cause of secondary blooming and mottling in CIDR inserts. However the root cause remains unknown.

year: 2006

title: Evidence for late polynesian colonization of New Zealand: University of Waikato radiocarbon measurements

authors: Hogg, Alan G.

subjects: radiocarbon

abstract: We present radiocarbon determinations for 271 New Zealand archaeological samples measured at the University of Waikato Radiocarbon Dating Laboratory between 1975 and 1995. A discard protocol is applied to the series and the list culled to winnow the acceptable dates from those that may incorporate error. None of the 221 acceptable ¹⁴C determinations older than 600 BP (in the case of terrestrial samples) or 930 BP (in the case of marine and estuarine shell) extends beyond cal AD 1250. This conclusion supports the short chronology model of New Zealand prehistory presented by Anderson (1991).

text: Evidence for late polynesian colonization of New Zealand: University of Waikato radiocarbon measurements We present radiocarbon determinations for 271 New Zealand archaeological samples measured at the University of Waikato Radiocarbon Dating Laboratory between 1975 and 1995. A discard protocol is applied to the series and the list culled to winnow the acceptable dates from those that may incorporate error. None of the 221 acceptable ¹⁴C determinations older than 600 BP (in the case of terrestrial samples) or 930 BP (in the case of marine and estuarine shell) extends beyond cal AD 1250. This conclusion supports the short chronology model of New Zealand prehistory presented by Anderson (1991).

year: 1997