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Cleavage of siloxane bonds (Si-O) in organosiloxanes (OSs) is one of the most fundamentally and practically important challenges in the modern chemistry of silicones. However, no benign approaches have been found to cleave these bonds under mild conditions. In this paper, siloxane bond cleavage in polydimethylsiloxane (PDMS) was studied using a mixture of the “green” reagent dimethyl carbonate (DMC) and an environmentally benign reagent, tris(pentafluorophenyl)borane (B(C6F5)3). The obtained results indicate that the Si-O bonds are cleaved by reaction with DMC to form lower-weight polymer fragments with alkoxy end groups, while the addition of B(C6F5)3 to the depolymerizing mixture significantly increases the degree of PDMS depolymerization at room temperature or with increasing temperature. Quantum chemical calculations show that the DMC molecules form stable complexes with B(C6F5)3 by preferable formation of C=O····B bonds, which increases the solvation effects and kinetic energy upon collision with PDMS. This result provides an appropriate electronic structure and orientation for the complexes for more effective interaction with Si-O-Si via a concert mechanism. This proposed benign approach can be used for the production of new OS polymers, silicone recycling and functionalization of metal or metalloid oxides. We report a novel approach of siloxane bond splitting in organosiloxane using mixture of tris(pentafluorophenyl)borane and dimethyl carbonate. In the first part of this note, depolymerization of polydimethylsiloxane by dimethyl carbonate and with the addition of tris(pentafluorophenyl)borane is studied. Reactions are studied at different concentrations of above-mentioned reagents and temperature while the second part of this note represents theoretical calculation results which explain the mechanism of the depolymerization reaction.

The mayfly Acanthophlebia cruentata of Aotearoa, New Zealand, is widespread in Te Ika-a-Māui North Island streams, but has never been collected from South Island despite land connection during the last glacial maximum. Population structure of this mayfly might reflect re-colonisation after volcanic eruptions in North Island c1800 years ago, climate cycling or conceal older, cryptic diversity. We collected population samples from 33 locations to estimate levels of population genetic diversity and to document phenotypic variation. Relatively low intraspecific haplotype divergence was recorded among mitochondrial cytb sequences from 492 individuals, but these resolved three geographic-haplotype regions (north, west, east). We detected a signature of isolation by distance at low latitudes (north) but evidence of recent population growth in the west and east. We did not detect an effect of volcanic eruptions but infer range expansion into higher latitudes from a common ancestor during the last glacial period. As judged from wing length, both sexes of adult mayflies were larger at higher elevation and we found that haplotype region was also a significant predictor of Acanthophlebia cruentata size. This suggests that our mitochondrial marker is concordant with nuclear genetic differences that might be explained by founder effect during range expansion.

The mayfly

Various nanostructured amorphous silicas [fumed silicas such as crude (A-300), hydro-compacted (cA-300, TS 100), and precipitated silica Syloid 244] were modified by different polydimethylsiloxanes such as PDMS5, PDMS100, PDMS200, PDMS1000, and PDMS12500 (the label numbers show the viscosity (η) values) using dimethyl carbonate (DMC) as a siloxane-bond-breaking reagent. In addition, hexamethyldisilazane was used to modify fumed silica cA-300. The nanocomposites were characterized using microscopy, infrared spectroscopy, thermodesorption, nitrogen adsorption–desorption, solid-state NMR spectroscopy, small-angle X-ray scattering, and zeta-potential methods. It was found that the morphological, textural, and structural characteristics of silicas grafted with PDMS depend strongly not only on the type and content of the polymers used but also on the organization of nonporous nanoparticles (NPNP) in secondary structures (aggregates of NPNP and agglomerated aggregates, ANPNP), as well on the reaction temperature (Tr). Specifically, we determined that ANPNP with a macro/mesoporous character are favorable for the effective modification of the silicas studied with short polymers and no DMC addition but at higher temperatures or for a longer silicone polymer with the presence of DMC and at lower temperatures. In particular, the PDMS/DMC-modified silicas are of great interest from a practical point of view because they remain in a dispersed state with no strong compaction of the secondary structures after modification, and this corresponds to a better distribution of the modified nanoparticles in polymeric or other matrices.

Three poly(organosiloxanes) (hydromethyl-, dimethyl-, and epoxymethylsiloxane) of different chain lengths and pendant groups and their mixtures of dimethyl (DMC) or diethyl carbonates (DEC) were applied in the modification of fumed silica nanoparticles (FSNs). The resulting modified silicas were studied in depth using 29Si, 1H, and 13C solid-state NMR spectroscopy, elemental analysis, and nitrogen adsorption-desorption (BET) analysis. The obtained results reveal that the type of grafting, grafting density, and structure of the grafted species at the silica surface depend strongly on the length of organosiloxane polymer and on the nature of the “green” additive, DMC or DEC. The spectral changes observed by solid-state NMR spectroscopy suggest that the major products of the reaction of various organosiloxanes and their DMC or DEC mixtures with the surface are D (RR’Si(O0.5)2) and T (RSi(O0.5)3) organosiloxane units. It was found that shorter methylhydro (PMHS) and dimethylsiloxane (PDMS) and their mixtures with DMC or DEC form a denser coverage at the silica surface since S BET diminution is larger and grafting density is higher than the longest epoxymethylsiloxane (CPDMS) used for FSNs modification. Additionally, for FSNs modified with short organosiloxane PMHS/DEC and also medium organosiloxane PDMS/DMC, the dense coverage formation is accompanied by a greater reduction of isolated silanols, as shown by solid-state 29Si NMR spectroscopy, in contrast to reactions with neat organosiloxanes. The surface coverage at FSNs with the longest siloxane (CPDMS) greatly improves with the addition of DMC or DEC. The data on grafting density suggest that molecules in the attached layers of FSNs modified with short PMHS and its mixture of DMC or DEC and medium PDMS and its mixture of DMC form a “vertical” orientation of the grafted methylhydrosiloxane and dimethylsiloxane chains, in contrast to the reaction with PDMS/DEC and epoxide methylsiloxane in the presence of DMC or DEC, which indicates a “horizontal” chain orientation of the grafted methyl and epoxysiloxane molecules. This study highlights the major role of solid-state NMR spectroscopy for comprehensive characterization of solid surfaces. Graphical abstract

Interest in development of potent, selective inhibitors of the phosphatase from the receptor type protein tyrosine phosphatase PTPRD as antiaddiction agents is supported by human genetics, mouse models and studies of our lead compound PTPRD phosphatase inhibitor, 7-butoxy illudalic acid analog 1 (7-BIA). We now report structure-activity relationships for almost 70 7-BIA-related compounds and results that nominate a 7- cyclopentyl methoxy analog as a candidate for further development. While efforts to design 7-BIA analogs with substitutions for other parts failed to yield potent inhibitors of PTPRD’s phosphatase, ten 7-position substituted analogs displayed greater potency at PTPRD than 7-BIA. Several were more selective for PTPRD vs the receptor type protein tyrosine phosphatases S, F and J or the nonreceptor type protein tyrosine phosphatase N1 (PTPRS, PTPRF, PTPRJ or PTPN1/PTP1B), phosphatases at which 7-BIA displays activity. In silico studies aided design of novel analogs. A 7-position cyclopentyl methoxy substituted 7-BIA analog termed NHB1109 displayed 600-700 nM potencies in inhibiting PTPRD and PTPRS, improved selectivity vs PTPRS, PTPRF, PTPRJ or PTPN1/PTP1B phosphatases, no substantial potency at other protein tyrosine phosphatases screened, no significant potency at any of the targets of clinically-useful drugs identified in EUROFINS screens and significant oral bioavailability. Oral doses up to 200 mg/kg were well tolerated by mice, though higher doses resulted in reduced weight and apparent ileus without clear organ histopathology. NHB1109 provides a good candidate to advance to in vivo studies in addiction paradigms and toward human use to reduce reward from addictive substances.

Three poly(organosiloxanes) (hydromethyl-, dimethyl-, and epoxymethylsiloxane) of different chain lengths and pendant groups and their mixtures of dimethyl (DMC) or diethyl carbonates (DEC) were applied in the modification of fumed silica nanoparticles (FSNs). The resulting modified silicas were studied in depth using 29Si, 1H, and 13C solid-state NMR spectroscopy, elemental analysis, and nitrogen adsorption-desorption (BET) analysis. The obtained results reveal that the type of grafting, grafting density, and structure of the grafted species at the silica surface depend strongly on the length of organosiloxane polymer and on the nature of the “green” additive, DMC or DEC. The spectral changes observed by solid-state NMR spectroscopy suggest that the major products of the reaction of various organosiloxanes and their DMC or DEC mixtures with the surface are D (RR’Si(O0.5)2) and T (RSi(O0.5)3) organosiloxane units. It was found that shorter methylhydro (PMHS) and dimethylsiloxane (PDMS) and their mixtures with DMC or DEC form a denser coverage at the silica surface since SBET diminution is larger and grafting density is higher than the longest epoxymethylsiloxane (CPDMS) used for FSNs modification. Additionally, for FSNs modified with short organosiloxane PMHS/DEC and also medium organosiloxane PDMS/DMC, the dense coverage formation is accompanied by a greater reduction of isolated silanols, as shown by solid-state 29Si NMR spectroscopy, in contrast to reactions with neat organosiloxanes. The surface coverage at FSNs with the longest siloxane (CPDMS) greatly improves with the addition of DMC or DEC. The data on grafting density suggest that molecules in the attached layers of FSNs modified with short PMHS and its mixture of DMC or DEC and medium PDMS and its mixture of DMC form a “vertical” orientation of the grafted methylhydrosiloxane and dimethylsiloxane chains, in contrast to the reaction with PDMS/DEC and epoxide methylsiloxane in the presence of DMC or DEC, which indicates a “horizontal” chain orientation of the grafted methyl and epoxysiloxane molecules. This study highlights the major role of solid-state NMR spectroscopy for comprehensive characterization of solid surfaces. Graphical abstract Electronic supplementary material The online version of this article (10.1186/s11671-019-2982-2) contains supplementary material, which is available to authorized users.

Herein we develop a quantitative dye dequenching technique for the measurement of polymersome fusion, using it to characterize the salt mediated, mechanically-induced fusion of polymersomes with polymer, lipid, and so-called stealth lipid vesicles. While dye dequenching has been used to quantitatively explore liposome fusion in the past, this is the first use of dye dequenching to measure polymersome fusion of which we are aware. In addition to providing quantitative results, dye dequenching is ideal for detecting fusion in instances where DLS results would be ambiguous, such as low yield levels and size ranges outside the capabilities of DLS. The dye chosen for this study was a cyanine derivative, 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbocyanine iodide (DiR), which proved to provide excellent data on the extent of polymersome fusion. Using this technique, we have shown the limited fusion capabilities of polymersome/liposome heterofusion, notably DOPC vesicles fusing with polymersomes at half the efficiency of polymersome homofusion and DPPC vesicles showing virtually no fusion. In addition to these key heterofusion experiments, we determined the broad applicability of dye dequenching in measuring kinetic rates of polymersome fusion; and showed that even at elevated temperatures or over multiple weeks' time, no polymersome fusion occurred without agitation. Stealth liposomes formed from DPPC and PEO-functionalized lipid, however, fused with polymersomes and stealth liposomes with relatively high efficiency, lending support to our hypothesis that the response of the PEO corona to salt is a key factor in the fusion process. This last finding suggests that although the conjugation of PEO to lipids increases vesicle biocompatibility and enables their longer circulation times, it also renders the vesicles subject to destabilization under high salt and shear (e.g. in the circulatory system) that may lead to, in this case, fusion.

Self-assembled giant polymer vesicles prepared from double-hydrophilic diblock copolymers, poly(ethylene oxide)-b-poly(acrylic acid) (PEO-PAA) show significant degradation in response to pH changes. Because of the switching behavior of the diblock copolymers at biologically-relevant pH environments (2 to 9), these polymer vesicles have potential biomedical applications as smart delivery vehicles.

In this work, we explore the depolymerization of poly(dimethylsiloxane) (PDMS-100) and poly(methylphenylsiloxane) (PMPS) using dimethyl carbonate (DMC) and develop a surface functionalization method by utilizing the DMC-imparted active methoxy end groups of the partially depolymerized polysiloxanes. The efficiency of dimethyl carbonate as a reagent for organosiloxane cleavage was confirmed by means of 1H NMR spectroscopy, size-exclusion chromatography, and viscosity measurements. The reaction of fumed silica with organosiloxanes (PMPS, PDMS-50) in the presence of DMC was investigated using the ζ-potential, 29Si and 13C solid-state NMR spectroscopy, IR spectroscopy, CHN analysis, contact angle goniometry, thermogravimetric analysis, scanning and transmission electron microscopy (TEM), and rheology. It was found that the interaction of PMPS/DMC with an SiO2 surface produced hydrophobic and thermally stable moieties (up to 550 °C) with a densely packed (average 2.2 groups/nm2) alkylsiloxane network for SiO2/...

Ratios of absorbances at two wavelengths have been used to quantify mixtures of photosynthetic pigments such as chlorophylls, phaeophytins and bacteriochlorophylls, however published methods have either specified an incorrect relationship between the absorbance ratio and the mixture, or only presented the relationship graphically. The correct relationship is established along with correct forms for equations to calculate pigment densities from absorbance ratios. The limitations of simple ratios and a diagnostic approach using difference spectra are illustrated with an example involving mixtures of oxygenic and anoxygenic phytoplankton communities in a stratified lake.

Polymersomes, hollow spherical nano-to-microscale polymer assemblies, have increasingly become important constructs in the development of biomimetic materials that expand the library of functional and robust analogs to lipid-based vesicles. As compared to liposomes, polymersomes possess superior physical properties and the nearly unlimited potential for synthetic fine-tuning. Herein we improve on the physical properties of these polymer vesicles by introducing platinum-based metal–ligand cross-links into the hydrophobic core, which gave the vesicles demonstrated resistance to destabilization by surfactants over un-cross-linked polymersomes. The formation of cross-links was capable of being selectively reversed by the addition of phosphines. In addition, the Pt(0) cross-links retained their catalytic activity for the hydrosilylation of alkenes.

Fossil evidence for the evolutionary history of terrestrial arthropods in New Zealand is extremely limited; only six pre-Quaternary insects (Triassic to Eocene) have been recorded previously, none of Miocene age. The Foulden Maar fossil lagerstatte in Otago has now yielded a diverse arthropod assemblage, including members of the Araneae, Plecoptera, Isoptera, Hemiptera, Coleoptera, Hymenoptera, Trichoptera and Diptera. The fauna significantly emends the fossil record for the Southern Hemisphere, provides an unparalleled insight into a 23-million-year-old New Zealand lake/forest palaeoecosystem and allows a first evaluation of arthropod diversity at a time coeval with or shortly after the maximum marine transgression of Zealandia in the late Oligocene. The well-preserved arthropods chiefly represent ground-dwelling taxa of forest floor and leaf litter habitats, mostly from sub-families and genera that are still present in the modern fauna. They provide precisely dated fossil evidence for the antiquity of some of New Zealand's terrestrial arthropods and the first potential time calibrations for phylogenetic studies. The high arthropod diversity at Foulden Maar, together with a subtropical rainforest flora and fossil evidence for complex arthropod–plant interactions, suggests that terrestrial arthropods persisted during the Oligocene marine transgression of Zealandia.

Polycarbonate is a desirable material for many applications due to its favorable mechanical and optical properties. Here, we report a simple, safe, environmentally friendly aqueous method that uses diamines to functionalize a polycarbonate surface with amino groups. The use of water as the solvent for the functionalization ensures that solvent induced swelling does not affect the optical or mechanical properties of the polycarbonate. We characterize the efficacy of the surface amination using X-ray photo spectroscopy, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and contact angle measurements. Furthermore, we demonstrate the ability of this facile method to serve as a foundation upon which other functionalities may be attached, including antifouling coatings and oriented membrane proteins.

Previously we have studied the mechanically-activated fusion of extruded (200 nm) polymer vesicles into giant polymersomes using agitation in the presence of salt. In this study we have investigated several factors contributing to this phenomenon, including the effects of (i) polymer vesicle concentration, (ii) agitation speed and duration, and iii) variation of the salt and its concentration. It was found that increasing the concentration of the polymer dramatically increases the production of giant vesicles through the increased collisions of polymersomes. Our investigations also found that increasing the frequency of agitation increased the efficiency of fusion, though ultimately limited the size of vesicle which could be produced due to the high shear involved. Finally it was determined that salt-mediation of the fusion process was not limited to NaCl, but is instead a general effect facilitated by the presence of solvated ionic compounds, albeit with different salts initiating fusion at different concentration.

The temperature-dependent aggregation and recovery of the copolymer poly(ethylene oxide)22-b-poly(N-isopropylacrylamide)29 with a C12 end-cap in aqueous solutions of salts and acids are investigated. Salt solutions affected the critical aggregation temperature of the copolymer in a manner predictable according to the Hofmeister series, with the kosmotropic adipic ion lowering the critical aggregation temperature and the chaotropic iodide raising it. Also, both salts and acids increased the size of copolymer aggregates formed with heating, due to the electrostatic shielding of aggregated structures provided by the electrolytes. Additionally, the presence of ionic additives caused a thermohysteretic increase in the size of copolymer aggregates with temperature cycling. The transitions of polymer structure with increasing temperature were surprisingly sharp with the C12 end-cap present, and particularly broad in samples in which the end cap had been cleaved. This observation suggested that the hydrophobic end group was responsible for imparting some degree of order to the polymer at low temperatures, which allowed for rapid reconfiguration with increasing temperature. Finally, in addition to the transitions expected from the least critical solution temperature behavior of the polymer blocks, we have observed an unexpected additional transition which we attribute to the contraction of the poly(ethylene oxide) chains of the copolymer aggregates at higher temperatures. This work illustrates the importance of considering the environment and composition of thermoresponsive block copolymers in certain applications, particularly in solutions with even modest electrolyte concentrations (1–10 mM), as it can have a profound effect on transition temperatures and morphology. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 507–516

We describe a new approach to synthesize 2,2'-bipyridine- or 2,2':6',2"-terpyridine-terminated polystyrene that relies on anionic polymerization and direct end-capping with the desired pyridyl species. End-functionalization occurs by nucleophilic addition of the living polystyryllithium chain to the 6-position of the pyridine ring, followed by termination and oxidative rearomatization. By using an excess of the pyridyl species to avoid coupling of two living chains through addition to the same bipyridine or terpyridine unit, this technique yielded samples consisting of 77-93% singly end-functionalized chains. The functionality of the polymers was determined by nuclear magnetic resonance spectroscopy and chromatographic separation, while molecular weight and polydipersity were determined by size exclusion chromatography. The crude products were easily purified to near-quantitative functionalization by short column chromatography, and the excess pyridyl species could be efficiently recovered and reused. Even though the addition of the polystyrene chain to the 6-position provides some steric hindrance to the ability of pyridyl end-caps to serve as ligands, the terpyridine-functionalized products were found to form bis complexes readily upon addition of 0.5 equiv of iron(II) chloride to a solution of the polymers, as determined by ultraviolet-visible spectrophotometry and nuclear magnetic resonance spectroscopy.

A yield-per-recruit model is developed for the recreational fishery on blue cod (Parapercis colias: Pinguipedidae) in the Marlborough Sounds, New Zealand. The model incorporates sex differences in growth rates, protogyny, minimum size limits, catch-and-release mortality and size-selective fishing. Mortality of released fish due to hooking damage and post-release predation is a potentially significant factor for blue cod management. High levels of catch-and-release mortality favour small minimum size limits and reduced fishing intensity. Even in the absence of size limits, hook and line fishing for blue cod is highly selective on larger fish and this greatly reduces the potential impact of catch-and-release mortality on yields and management choices. Catch-and-release mortality will also lower the spawning stock biomass-per-recruit and therefore has the potential to impact on stock sustainability as well as yields. In protogynous species the effects of fishing on spawning stock biomass will be different for males and females and it is important to model these separately, as well as understanding the cues for, or timing and extent of, sex change. Catch-and-release mortality can also slow the recovery of stocks when no-take rules still allow fishing for other species and therefore by-catch of the species targeted for protection. It is suggested that a small reduction in size limit and a small increase in daily bag limit relative to present regulations, would result in optimal yields from this fishery. Predation on fish released by recreational anglers is less widely reported than mortality due to hooking damage but both have the potential to negate the benefits of minimum size limits.

Three new species of caddis in the endemic New Zealand genus Alloecentrella Wise, 1958 (Trichoptera: Sericostomatoidea) are named and described: A. linearis sp. n., A. cirratus sp. n., and A. incisus sp. n. We report the known distribution of each of the four species in the genus; A. magnicornis and A. incisus appear to be found only in North Island; A. linearis and A. cirratus have been recorded only from South Island. We provide characters to differentiate the larvae (extent of the head carina; the shape of the head capsule in lateral profile) and cases (position of the terminal aperture). We present the results of a phylogenetic analysis of larval, pupal and adult morphological characters which places Alloecentrella in the Helicophidae.

We describe for the first time how biological nanomotors may be used to actively self-assemble mesoscale networks composed of diblock copolymer nanotubes. The collective force generated by multiple kinesin nanomotors acting on a microtubule filament is large enough to overcome the energy barrier required to extract nanotubes from polymer vesicles comprised of poly(ethylene oxide-b-butadiene) in spite of the higher force requirements relative to extracting nanotubes from lipid vesicles. Nevertheless, large-scale polymer networks were dynamically assembled by the motors. These networks displayed enhanced robustness, persisting more than 24 h post-assembly (compared to 4–5 h for corresponding lipid networks). The transport of materials in and on the polymer membranes differs substantially from the transport on analogous lipid networks. Specifically, our data suggest that polymer mobility in nanotubular structures is considerably different from planar or 3D structures, and is stunted by 1D confinement of the polymer subunits. Moreover, quantum dots adsorbed onto polymer nanotubes are completely immobile, which is related to this 1D confinement effect and is in stark contrast to the highly fluid transport observed on lipid tubules.

Four types of coarse particulate organic matter (CPOM), 100 mm and 200 mm lengths of wooden dowel, paper strips and Eucalyptus leaves, were released in either straightened or naturally meandering sections of a third-order stream in lower North Island, New Zealand. The distance travelled until retained and the fate of each CPOM type were recorded over a range of discharges (0.10–0.77 m3 s−1) in stream sections with differing riparian characteristics (forest, willow and pasture). In meanders, CPOM travelled a shorter distance until retention and a higher proportion of released CPOM was retained compared to straightened reaches. CPOM travelled further until retention in pasture sections. Snags (vegetation and debris) were more important than rocks and eddies as retention structures, but more items were trapped by eddies in straightened reaches than in meanders. Leafy CPOM (paper strips and Eucalyptus) were retained more than wooden dowels, with paper strips behaving in a similar fashion to Eucalyptus leaves. Longer dowels were retained more than shorter ones. Changes to the channel form of this stream have significantly affected the rate and nature of CPOM retention which in turn could impact on stream ecosystem structure and productivity. Copyright © 2005 John Wiley & Sons, Ltd.

The parasitoid guild attacking preimaginal Tortricidae on shrubs and small trees in broadleaf/podocarp forests was studied at six sites in the central North Island. Connectance and quantitative webs were used to interpret the complexities of host parasitoid interactions at a community level and identify competition between native parasitoids and the introduced species Trigonospila brevifacies (Hardy). Trigonospila brevifacies is numerically dominant in the tortricid parasitoid guild. Its host range overlaps with 12 native and one introduced parasitoid species, and it parasitizes more species of Tortricidae than other parasitoids at the North Island forest sites surveyed. Quantification of the parasitoid load on native Lepidoptera indicated that T. brevifacies parasitism comprised between 15.6 and 79.5% of the parasitoid load per species. Only the introduced Australian canefruit pest Eutorna phaulocosma Meyrick (Lepidoptera: Oecophoridae) received a higher proportion of parasitism from T. brevifacies than any of the native Lepidoptera. The number of parasitoid species attacking each preimaginal host stage (except for pupae) of native Lepidoptera was relatively constant. The only pupal parasitoid recorded was the introduced ichneumonid Xanthopimpla rhopaloceros Krieger (Hymenoptera: Ichneumonidae). All native parasitoid species were less abundant than T. brevifacies.

Diadromous fish species dominate the New Zealand freshwater fish fauna and make up 15 of the 17 native fish species found on the Taranaki Ring Plain. Trajectories of occurrence in relation to elevation and distance from the sea are described for 11 diadromous and 2 non‐diadromous species using data from the New Zealand Freshwater Fish Database and data collected over the summer of 1997/ 98. Distinctive distributions were found for most of the species related to their differing migratory strategies and abilities. The species were ranked based on components of these trajectories to compare their penetrative ability. Comparison of the ranking methods used revealed they produced similar results. The ranking of the 11 diadromous species in Taranaki relative to each other revealed similar rankings to those for the same species from the West Coast of the South Island. The non‐migratory native fish, Cran's bully (Gobiomorphus basalis), was not found on the western side of the mountain. This distribution ...

Summary We measured the weight and volume of omasae, and the number, weight and area of omasal laminae from wild fallow (Cervus dama), and wild and farmed red deer (Cervus elaphus) whose diet, as indicated by rumen content, was known. A multivariate analysis yielded two principal components, interpreted as indices of overall omasal size and laminar leafiness. The second component showed significantly greater variance in wild red deer than in farmed red or wild fallow deer. Deer feeding on a mixed diet of browse and grasses may have greater variability of omasal form than those feeding on grass alone. A relationship is derived by which the laminar area can be estimated from counts of laminae in different size classes.

Previously published studies have related the surface area of rumen wall to diet. The validity of studies that utilize preserved material depends upon the predictability of any change in rumen dimension brought about by preservation. Changes in the surface are of different sections of the rumen wall of red deer (Cervus elaphus) were monitored after immersion in 10% formal saline solution at room temperature for 2, 7 and 14 days. There was a high degree of variability (0-39.5%) in wall-area reduction. Ignoring such changes when calculating the factor of increase in surface area (FISA), a composite of papillary surface area and density, can result in errors of up to 39.5%. This study questions the validity of using FISA calculations when formalin-preserved specimens are used in studies of rumen response to diet. Rumen papillary dimensions were not significantly changed by preservation in formalin.

Large (200 nm) poly(ethylene oxide)-b-poly(butadiene) polymer vesicles fuse into giant (>1 μm) vesicles with mild agitation in dilute aqueous NaCl solutions. This unusual effect is attributed to the salt-induced contraction of the poly(ethylene oxide) corona, reducing steric resistance between vesicles and, with agitation, increasing the probability of contact between the hydrophobic cores of adjacent membranes. In addition, NaCl and agitation facilitated the creation of giant hybrid vesicles from much smaller homogeneous polymersomes and liposomes. Whereas lipid vesicles do not readily fuse with each other under the same circumstances, they did fuse with polymersomes to produce hybrid polymer/lipid vesicles.

We measured the length and width of ruminal papillae from six sites in rumens of farmed and wild red (Cervus elaphus) and wild fallow (Cervus dama) deer. A multivariate (principal components) analysis was used to explore papillary response to habitat. Three axes of papillary variation were defined: overall size, shape, and site (anatomical location within the rumen). These axes responded differently according to age, sex, diet, and species. Overall papillary size increased with age in wild but not in farmed stock, was significantly affected by sex, but showed no interspecies difference. Papillary shape was not influenced by age, sex, or diet but was influenced by species. Site-specific development was influenced by diet and species but not by age or sex. These results corroborate previous descriptive work and offer a technique for quantitative study of the interaction between wild ruminants and their dietary environment.

We report the results of three independent light‐trapping studies of caddis (Trichoptera) at three widely‐separated stream‐side sites in New Zealand. A total of 66 caddis species in 10 families was recorded, as follows: 33 from site K (Kawarau Gorge) in 1990–91, 28 from site T (Turitea Stream) in 1986–87 and 45 from site W (Waitakere Stream/Cascade Stream) in 1967–68. Many of the species were captured in sufficient numbers to estimate their adult flight season. The results show that some species in the families Hydrobiosidae, Hydroptili‐dae and perhaps also Philopotamidae and Chathamiidae are present as adults during every month of the year. Species captured from 7 other families appeared to have a mid‐winter break with no active adults present. For some species there is a marked change in the sex ratio through the flight season from predominantly males early in the season to predominantly females at the end. For four common species at one site, the arrival pattern at the light trap was unimodal. It was h...

Polymersomes are being widely explored as synthetic analogs of lipid vesicles based on their enhanced stability and potential uses in a wide variety of applications in (e.g., drug delivery, cell analogs, etc.). Controlled formation of giant polymersomes for use in membrane studies and cell mimetic systems, however, is currently limited by low-yield production methodologies. Here, we describe for the first time, how the size distribution of giant poly(ethylene glycol)-poly(butadiene) (PEO-PBD) polymersomes formed by gel-assisted rehydration may be controlled based on membrane fluidization. We first show that the average diameter and size distribution of PEO-PBD polymersomes may be readily increased by increasing the temperature of the rehydration solution. Further, we describe a correlative relationship between polymersome size and membrane fluidization through the addition of sucrose during rehydration, enabling the formation of PEO-PBD polymersomes with a range of diameters, including giant-sized vesicles (>100 μm). This correlative relationship suggests that sucrose may function as a small molecule fluidizer during rehydration, enhancing polymer diffusivity during formation and increasing polymersome size. Overall the ability to easily regulate the size of PEO-PBD polymersomes based on membrane fluidity, either through temperature or fluidizers, has broadly applicability in areas including targeted therapeutic delivery and synthetic biology.

We investigated whether blue ducks Hymenolaimus malacorhynchos preferentially capture prey that have themselves become rare or that need to be present for successful re-establishment. Working at the Manganuiateao River in New Zealand, we measured the densities and relative abundances of benthic invertebrates, numbers of prey fragments in faeces of adult ducks, and foraging behaviour of adult ducks. Invertebrate densities on stones ranged from 3741 m−2 to 14,417 m−2. Stone and boulder communities were dominated by cased caddisfly larvae or Chironomidae larvae in most months. Patterns of apparent selectivity varied, but Trichoptera larvae in the family Hydrobiosidae and in the genus Aoteapsyche (Hydropsychidae) ranked highly, and cased caddis larvae consistently ranked low, in the diet. Discriminant function analysis indicated that apparent prey preferences were partly related to whether foraging blue ducks were gleaning from the tops or undersides of rocks in the river. Canonical correlation analysis showed that ingestion of stonefly and mayfly larvae was associated with diving behaviour, but it was not possible to predict the ingestion of other prey from foraging tactics. No single prey category was so highly valued by the blue ducks we studied that it might limit population establishment at new sites.

Regression equations are presented for the estimation of dry weight from head width and body length for 20 common New Zealand stream‐dwelling macroinvertebrate taxa. Equations for taxa grouped at order level are also provided. A power equation, y = a x b is used to express the relationship between dry weight and body size. For the majority of taxa, dry weight could be estimated with more precision from body length than from head width.

2-Hydroxypentadienoic acid is shown to be a biochemical intermediate on the phenylpropionate catabolic pathway of Escherichia coli; its stability and ketonisation behaviour are compared with those of its homologue, enolpyruvate.

Metallo-supramolecular assemblies of polymeric, particulate, or small-molecule building blocks based on 2,2′:6′,2′′-terpyridine most commonly rely on chemical substitution of this ligand at the 4′ position. Here, we investigate the effects that this modification to the ligand have on the kinetic stabilities of bis transition metal complexes, and therefore the lifetime of supramolecular bonds that it forms. The decay of aqueous cobalt(II) and iron(II) complexes in the presence of excesses of competing metal ions is studied by ultraviolet visible (UV-vis) absorption spectroscopy, and rate constants for the decay of amino-, ether-, and non-substituted ligands are determined. Remarkably, for cobalt(II), amino substituents lead to rapid oxidation in air to kinetically inert cobalt(III) complexes, while ether substituents yield decay constants three- to six-fold larger than unsubstituted complexes. Ether linkages apparently weaken cobalt complexes by inductive withdrawal of electrons, while amino substituents donate electron density, thus lowering the oxidation potential of the complexes. For iron(II), both ether- and amino-linked complexes decay at least an order of magnitude faster than unsubstituted complexes. Our results highlight the importance of considering linking chemistry when designing dynamic supramolecular assemblies based on terpyridine ligands, as it yields significant, and occasionally dramatic, changes in the kinetic stabilities of these complexes.

Though 2,2′:6′,2′′-terpyridine is commonly used as a ligand for forming metallo-supramolecular assemblies in a variety of solvent environments, little is known about how the properties of the medium influence its behavior. We have studied the kinetic stabilities of bis terpyridine complexes with iron(II) and cobalt(II), and found variations in decay rate between commonly employed solvents of more than five orders of magnitude for iron, and thirty-fold for cobalt. While numerous factors likely contribute to these effects, a clear correlation between the decay rates of the iron complexes and the solubility of terpyridine suggests that favorable solvent–ligand interactions may lower the activation barrier for dissociation by stabilizing the transition state. These results illustrate the importance of solvent selection when designing metallo-supramolecular assemblies based on terpyridine, and also provide insights for further tuning the dynamic properties of these complexes.

2-Hydroxypentadienoic acid is shown to be a biochemical intermediate on the phenylpropionate catabolic pathway of Escherichia coli; its stability and ketonisation behaviour are compared with those of its homologue, enolpyruvate.

Recent methodological developments in historical biogeography generally treat biogeographic distribution as synonymous with occupancy of 'areas'. The aim of biogeographic analysis has been to determine the historical relationships of these areas using information from the distributions and phylogenetic relationships of animals and plants. While this may be of interest to geologists, it is of little interest to most biologists since it offers no direct insight into the historical processes that generate biogeographic patterns. Attempts to use relationships of areas (obtained from biogeographic patterns) to understand biogeographic processes can involve circularity. Focusing on relationships of areas relegates biology to a minor consideration in biogeography. This has resulted in the unfortunate dichotomy between 'ecological' and 'historical' biogeography. A biogeography of areas also limits the information potentially available from biogeographic distributions. Choice of areas for biogeographic analysis can be problematical and analysis is sensitive to this choice. Problems in identifying and analysing biogeographic areas are illustrated with trans-oceanic and local examples of austral biogeography.

The study of phylogeny is becoming increasing scientific in that hypotheses can be tested quantitatively. We report a method of estimating the probabilities of obtaining a tree of a given length from nucleic acid sequence data. The method is applied to the hypothesis of Hoyle & Wickramasinghe that the earth is being continually bombarded by influenza (and other) viruses which originate from comets. A quantitative analysis of sequences from the H1 strain of human influenza viruses contradicts three versions of the Hoyle-Wickramasinghe model. One non-evolutionary version of their model has less than one chance in 10(66) of being correct. A version that allowed extraterrestrial evolution has less than one change in 10(6) of being correct. The sequence data is in agreement with the biological (evolutionary) model. The results are discussed from the aspect of the falsifiability of evolutionary theory.