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A robust route to produce poly(methyl methacrylate) (pMMA) hybrid latex particles (radius ∼250 nm) that are selectively “armored” with silica nanoparticles (radius 12.5 nm) through addition of vinyltriethoxysilane was previously shown (J. Colloid Interface Sci.2018, 528, 289–300).Depending on synthesis conditions, the extent of nanoparticle attachment could be varied; however, the mechanism behind this attachment during latex growth remained unclear. The dual population of particles present (silica + polymer) means that particle sizing by dynamic light scattering is ambiguous. Furthermore, the low glass transition temperature (Tg) of polymers such as poly(butyl acrylate) (pBA) typically used in film-forming applications for decorative coatings (i.e., paints) means that the hybrid latex particles are too “soft” for robust analysis through atomic force microscopy (AFM) and scanning electron microscopy (SEM). Here, we show that small- and ultrasmall-angle neutron scattering (SANS and USANS), along with complementary data from small-angle X-ray scattering (SAXS), reveals that these armored hybrid latex particles adopt a raspberry-type configuration, supporting their core–shell structure. The number of nanoparticles present on the surface of the hybrid latex can be adjusted by addition of one of a diverse range of alkyl- or perfluoroalkyl-silanes to alter silica nanoparticle hydrophobicity, and quantified through analysis of scattering data. The approach therefore provides a novel, nonperturbative, and in situmethod of quantifying nanoparticle attachment to polymer latex particles.

For evolving biological and biomedical applications of hybrid protein?lipid materials, understanding the behavior of the protein within the lipid mesophase is crucial. After more than two decades since the invention of the in meso crystallization method, a protein-eye view of its mechanism is still lacking. Numerous structural studies have suggested that integral membrane proteins preferentially partition at localized flat points on the bilayer surface of the cubic phase with crystal growth occurring from a local fluid lamellar L?phase conduit. However, studies to date have, by necessity, focused on structural transitions occurring in the lipid mesophase. Here, we demonstrate using small-angle neutron scattering that the lipid bilayer of monoolein (the most commonly used lipid for in meso crystallization) can be contrast-matched using deuteration, allowing us to isolate scattering from encapsulated peptides during the crystal growth process for the first time. During in meso crystallization, a clear decrease in form factor scattering intensity of the peptides was observed and directly correlated with crystal growth. A transient fluid lamellar L?phase was observed, providing direct evidence for the proposed mechanism for this technique. This suggests that the peptide passes through a transition from the cubic QIIphase, via an L?phase to the lamellar crystalline Lcphase with similar layered spacing. When high protein loading was possible, the lamellar crystalline Lcphase of the peptide in the single crystals was observed. These findings show the mechanism of in meso crystallization for the first time from the perspective of integral membrane proteins.

The development of protein-based hydrogels for tissue engineering applications is often limited by their mechanical properties. Herein, we present the facile fabrication of tough regenerated silk fibroin (RSF)/graphene oxide (GO) nanocomposite hydrogels by a photochemical cross-linking method. The RSF/GO composite hydrogels demonstrated soft and adhesive properties during initial stages of photocrosslinking (<2 min), which is not observed for the pristine RSF hydrogel, and rendered a tough and nonadhesive hydrogel upon complete cross-linking (10 min). The composite hydrogels exhibited superior tensile mechanical properties, increased β-sheet content, and decreased chain mobility compared to that of the pristine RSF hydrogels. The composite hydrogels demonstrated Young’s modulus as high as ∼8 MPa, which is significantly higher than native cartilage (∼1.5 MPa), and tensile toughness as high as ∼2.4 MJ/m3, which is greater than that of electroactive polymer muscles and at par with RSF/GO composite membranes fabricated by layer-by-layer assembly. Small-angle scattering study reveals the hierarchical structure of photocrosslinked RSF hydrogels to comprise randomly distributed water-poor (hydrophobic) and water-rich (hydrophilic) regions at the nanoscale, whereas water pores and channels exhibiting fractal-like characteristics at the microscale. The size of hydrophobic domain (containing β-sheets) was observed to increase slightly with GO incorporation and/or alcohol post-treatment, whereas the size of the hydrophilic domain (intersheet distance containing random coils) was observed to increase significantly, which influences/affects water uptake capacity, cross-link density, and mechanical properties of hydrogels. The presented results have implications for both fundamental understanding of the structure–property relationship of RSF-based hydrogels and their technological applications.

The formation of amyloid deposits is a common feature of a broad range of diseases, including atherosclerosis, Alzheimer’s disease, and Parkinson’s disease. The basis and role of amyloid deposition in the pathogenesis of these diseases is still being defined, however an interesting feature of amyloidogenic proteins is that the majority of the pathologically associated proteins are involved in lipid homeostasis, be it in lipid transport, incorporation into membranes, or the regulation of lipid pathways. Thus, amyloid-forming proteins commonly bind lipids, and lipids are generally involved in the proper folding of these proteins. However, understanding of the basis for these lipid-related aspects of amyloidogenesis is lacking. Thus, we have used the apolipoprotein C-II amyloid model system in conjunction with x-ray and neutron scattering analyses to address this problem. Apolipoprotein C-II is a well-studied model system of systemic amyloid fibril formation, with a clear and well-defined pathway for fibril formation, where the effects of lipid interaction are characterized, particularly for the lipid mimetic dodecylphosphocholine. We show that the micellar state of an inhibitory lipid can have a very significant effect on protein conformation, with micelles stabilizing a particular α-helical structure, whereas submicellar lipids stabilize a very different dimeric, α-helical structure. These results indicate that lipids may have an important role in the development and progression of amyloid-related diseases.

The self-assembly of ordered structures in mixtures of oppositely charged surfactant and polymer systems has been exploited in various cleaning and pharmaceutical applications and continue to attract much interest since their discovery in the late twentieth century. The ability to control the electrostatic and hydrophobic interactions that dictate the formation of liquid crystalline phases in these systems is advantageous in manipulation of structure and rendering them responsive to external stimuli. Nanostructured capsules comprised of the cationic surfactant, cetyltrimethylammonium bromide (CTAB), and the diblock copolymer poly(acrylamide-acrylic acid) (PAAm-AA) were prepared to assess their potential as pH responsive nanomaterials. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified coexisting Pm3ncubic and hexagonal phases at the surfactant–polymer interface. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and solution pH, respectively, and were found to influence the liquid crystalline nanostructure formed. The lattice parameter of the mesophases and the fraction of cubic phase in the system decreased upon heating. Acidic conditions resulted in the loss of the highly ordered structures due to protonation of the carboxylic acid group, and subsequent reduction of attractive forces previously present between the oppositely charged molecules. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from nanostructured macro-sized capsules significantly increased when the pH of the solution was adjusted from pH 7 to pH 2. This allowed for immediate release of the compound of interest “on demand”, opening new options for structured materials with increased functionality over typical layer-by-layer capsules.

Soft corona structures of DNA-capped nanoparticles are crucial for their applications in diagnostics, gene delivery, and superlattice growth. While conventional X-ray techniques can only provide information on their inorganic cores, here we report substantial new insights of DNA corona structures within DNA-capped nanoparticles in this first study employing small angle neutron scattering (SANS). Using two 15-mer DNA strands with palindromic sequence and poly(dT) sequence under high number density packing on gold nanoparticle surfaces, the influence of ionic strength and temperature on DNA corona structures and resultant hybridization has been investigated. Poly(dT) sequences were found to maintain globular corona structures across a range of ionic strengths and temperatures, but the corona thickness decreased with increasing salt concentration and increased with increasing temperature. In contrast, palindromic sequenced DNA had globular corona structures in the absence of salt but quickly evolved into dimeric and multimeric structures under high ionic strength or under low annealing temperatures. The structural insights revealed by SANS can guide the design of tailor-made DNA corona structures for customizable designer materials and devices.

Esophageal cancer patients are often diagnosed as “advanced” cases. These patients are subjected to palliative stenting using self-expanding metallic stents (SEMS) to maintain oral alimentation. Unfortunately, SEMS get reoccluded due to tumor growth, in and over the stent struts. To investigate potential solutions to this problem, docetaxel (DTX) delivery films were prepared using PurSil AL 20 (PUS), which can be used as a covering material for the SEMS. Drug–polymer miscibility and interactions were studied. Bilayer films were prepared by adhering the blank film to the DTX loaded film in order to maintain the unidirectional delivery to the esophagus. In vitrorelease and the local DTX delivery were studied using in vitropermeation experiments. It was found that DTX and PUS were physically and chemically compatible. The bilayer films exhibited sustained release (>30 days) and minimal DTX permeation through esophageal tissues in vitro. The rate-determining step for the DTX delivery was calculated. It was found that >0.9 fraction of rate control lies with the esophageal tissues, suggesting that DTX delivery can be sustained for longer periods compared to the in vitrorelease observed. Thus, the bilayer films can be developed as a localized sustained delivery system in combination with the stent.

Evaporation-induced self-assembly (EISA) of ordered mesoporous titania powders using block copolymer templates Brij 58 and F127 has been studied as a function of the precursor solution composition and age as well as the evaporation conditions. Small-angle X-ray scattering was used to monitor the degree of order in the mesoporous structure of materials synthesized under these varying conditions. Also, for the first time, the time-dependent formation of Ti structures in precursor solutions and the effect of those structures on the creation of mesostructural order have been demonstrated. The interactions of the Ti precursor with Brij 58 and F127 were investigated and showed that the different templates caused formation of Ti oligomers of unique sizes and structures. Precursor solution composition and evaporation conditions were also shown to affect the order and stability of the mesoporous titania produced. Overall, this systematic study has provided fundamental insights into the synthesis conditions that maximize the degree of order and thermal stability of the final materials. These “optimal” conditions are highly dependent on the choice of template. As a result of this improved understanding, the synthesis of ordered mesoporous titania powders using the block copolymer F127 as a template has been achieved without the use of stabilizing agents for the first time.

Nanostructured capsules comprised of the anionic bile salt, sodium taurodeoxycholate (STDC), and the biocompatible cationic polymer, chitosan, were prepared to assess their potential as novel tailored release nanomaterials. For comparison, a previously studied system, sodium dodecyl sulfate (SDS), and polydiallyldimethylammonium chloride (polyDADMAC) was also investigated. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified the presence of lamellar and hexagonal phase at the surfactant–polymer interface of the respective systems. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and salt concentration, respectively, and were found to influence the liquid-crystalline nanostructure formed. The hexagonal phase persisted at high temperatures, however the lamellar phase structure was lost above ca. 45 °C. Both mesophases were found to dissociate upon addition of 4% NaCl solution. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from the lamellar phase significantly increased in response to changes in the solution conditions studied, suggesting that modulating the drug release from these bile salt–chitosan capsules is readily achieved. In contrast, release from the hexagonal phase capsules had no appreciable response to the stimuli applied. These findings provide a platform for these oppositely charged surfactant and polymer systems to function as stimuli-responsive or sustained-release drug delivery systems.

Smart protein: Careful design can yield novel biologically inspired materials that display advanced responsive behavior. A genetically engineered elastic protein displays both a lower and an upper critical solution temperature (LCST and UCST, see picture), and its photophysical behavior depends on solution pH value.

Sorgfältiges Designkann neuartige biologisch inspirierte Materialien ergeben, die ein verbessertes Ansprechverhalten zeigen. Ein gentechnisch hergestelltes, elastisches Protein hat sowohl eine untere als auch eine obere kritische Entmischungstemperatur (LCST bzw. UCST, siehe Bild); sein photopysikalisches Verhalten hängt vom pH‐Wert der Lösung ab.

A new type of supported liquid membrane was made by combining an ionic liquid (IL) with a Nafion membrane reinforced with multifunctional polyhedral oligomeric silsesquioxanes (POSSs) using a layer-by-layer strategy for anhydrous proton-exchange membrane (PEM) application. The POSS was functionalized by direct sulfonation, and the sulfonated POSS (S-POSS) was incorporated into Nafion 117 membranes by the infiltration method. The resultant hybrid membrane shows strong ionic interaction between the Nafion matrix and the multifunctional POSS, resulting in increased glass transition temperature and thermal stability at very low loadings of S-POSS (1%). The presence of S-POSS has also improved the proton conductivity especially at low humidities, where it shows a marked increase due to its confinement in the ionic domains and promotes water uptake by capillary condensation. In order to achieve anhydrous conductivity, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI) was incorporated into these membranes to provide proton conduction in the absence of water. Although the incorporation of an IL shows a plasticizing effect on the Nafion membrane, the S-POSS composite membrane with an IL shows a higher modulus at high temperatures compared to Nafion 117 and a Nafion−IL membrane, with significantly higher proton conductivity (5 mS/cm at 150 °C with 20% IL). This shows the ability of the multifunctional POSS and IL to work symbiotically to achieve the desirable proton conductivity and mechanical properties of such membranes by enhancing the ionic interaction within the material.

Three types of poly(ethylene terephthalate) (PET) were investigated: linear (unprocessed) bottle‐grade PET (intrinsic viscosity, IV ∼ 0.82 dL g−1); a branched PET produced from linear PET by reactive extrusion with 0.4% w/w pyromellitic dianhydride and pentaerythritol in 5:1 molar ratio (IV ∼ 0.97 dL g−1); and a control sample produced from the same linear PET by extrusion under the same conditions without the reactive agents (IV ∼ 0.71 dL g−1). A key finding is that the reactive extrusion process, presumably as a consequence of branching and branch distribution, significantly modifies the crystallisation kinetics and changes the final morphology. Using small‐angle X‐ray scattering (SAXS) and differential scanning calorimetry (DSC), the crystallisation kinetics of PET was monitored from the melt (270 °C) to a crystallisation temperature of either 205 or 210 °C. The IV of the branched PET was ∼ 21% greater than that of the unprocessed PET, and the rate of melt crystallisation (from DSC measurements) was 510 s for the branched, 528 s for the control, and 640 s for the unprocessed PET. The lamellae spacings measured from the equilibrium SAXS patterns were ∼160 ± 10 Å for the branched PET and ∼180 ± 10 Å for the unprocessed PET. Such properties offer the potential for new applications requiring high‐melt‐strength PET. Copyright © 2006 Society of Chemical Industry

Two organically modified layered silicates (with small and large diameters) were incorporated into three segmented polyurethanes with various degrees of microphase separation. Microphase separation increased with the molecular weight of the poly(hexamethylene oxide) soft segment. The molecular weight of the soft segment did not influence the amount of polyurethane intercalating the interlayer spacing. Small‐angle neutron scattering and differential scanning calorimetry data indicated that the layered silicates did not affect the microphase morphology of any host polymer, regardless of the particle diameter. The stiffness enhancement on filler addition increased as the microphase separation of the polyurethane decreased, presumably because a greater number of urethane linkages were available to interact with the filler. For comparison, the small nanofiller was introduced into a polyurethane with a poly(tetramethylene oxide) soft segment, and a significant increase in the tensile strength and a sharper upturn in the stress–strain curve resulted. No such improvement occurred in the host polymers with poly(hexamethylene oxide) soft segments. It is proposed that the nanocomposite containing the more hydrophilic and mobile poly(tetramethylene oxide) soft segment is capable of greater secondary bonding between the polyurethane chains and the organosilicate surface, resulting in improved stress transfer to the filler and reduced molecular slippage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 128–139, 2006

The curing kinetics and morphology of an interpenetrating polymer network (IPN) formed from an epoxy resin (DGEBA) cured by an imidazole (1‐MeI) and a dimethacrylate resin (bisGMA), cured by low‐ and high‐temperature peroxide initiators (TBPEH and DHPB, respectively) have been studied by temperature‐ramping DSC, isothermal near‐infrared (NIR), DMTA and small‐angle neutron scattering (SANS). bisGMA and DGEBA are polar and chemically similar thermosetting resins which should enhance the miscibility of their IPNs. The phase structure was controlled by varying the curing procedure: the order of gelation of the components is dependent on the choice of low‐ and high‐temperature initiators for bisGMA and this affects the morphology formation. In the cure of the bisGMA/TBPEH:DGEBA/1‐MeI system, the dimethacrylate cures first. For isothermal cure studies at 80 °C, the final conversion of the epoxy is reduced by high crosslinking of the methacrylate groups in the IPN causing vitrification before full cure. The dimethacrylate conversion is enhanced due to plasticisation with unreacted DGEBA, and its cure rate is increased due to accelerated decomposition of TBPEH initiator by 1‐MeI. SANS revealed that phase separation occurs in these IPNs with domains on the scale of 6–7 nm. In the cure of the bisGMA/DHBP:DGEBA/1‐MeI system, the epoxy cures at a similar rate to that of the methacrylate groups. For isothermal cure studies at 80 °C, similar final conversions of the epoxy have been observed except for the 75:25 IPN. The cure rate of the methacrylate groups in the IPN is increased also due to accelerated decomposition of DHBP initiator by 1‐MeI, and the extent of accelerated decomposition for DHBP is stronger than that in the TBPEH‐based systems. SANS studies revealed that this system is more homogeneous due to the rapid formation of the dimethacrylate gel in the presence of the preformed epoxy network which interlocks the networks at low degrees of methacrylate conversion. Copyright © 2006 Society of Chemical Industry

Small‐angle X‐ray scattering (SAXS) studies were undertaken to explore possible morphological explanations for poor mechanical strength in the petaloid bases of poly(ethylene terephthalate) (PET) bottles. The bottles were manufactured using a two‐stage injection stretch blow molding process. Splitting of PET bottle bases under load is both inconvenient and expensive. In this study, SAXS data were collected with a 100 μm square X‐ray beam to establish the molecular morphology as a function of position across the base topology. An amorphous region was identified in the base center (i.e., close to the injection gate of the preform) with biaxially orientated, semicrystalline regions in the feet and valleys of the bottle bases. For bottles that had split under load, the transition between these two regions displayed uniaxial orientation that would lead to reduced mechanical strength in the circumferential direction. Reasons for this effect are explored. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3328–3335, 2006

The structures of three trishomocubanes of types pentacyclo[5.4.0.0 2,6 .0 3,10 .0 5,9 ]undecylamines and 4-azahexacyclo[5.4.1.0 2,6 .0 3,10 .0 5,9 .0 8,11 ]dodecanes have been determined. These ligands have demonstrated high selectivity and affinity for the sigma binding site, a molecular binding site important in the study of neurological disorders. The three compounds reported are members of an extensive series of ligands under investigation in a search for more efficacious pharmaceuticals. Compound (3) crystallized in the monoclinic space group C2/c with a 15.821(8), b 22.407(10), c 11.032(6) &Aring;, β 115.15(3)&deg;, V 3540(3) &Aring; 3 , Z 8, and was refined to an R value of 0.054 on 1161F. Compound (4) crystallized in the triclinic, space group P1, a 11.278(3), b 13.139(2), c 7.444(2) &Aring;, α 104.54(1), β 107.85(2), γ 68.51(1)&deg;, V 964.9(4) &Aring; 3 , Z 2, and was refined to an R value of 0.061 on 1939F. Compound (6) crystallized in the monoclinic space group P2 1 /c, a 9.971(4), b 11.989(4), c 12.993(5) &Aring;, β 108.68(3)&deg;, V 1471(1) &Aring;3 , Z 4, and was refined to an R value of 0.060 on 1303F. The results are in accord with the hypothesis that the spatial relationship between the amine group and the hydrophobic regions of the molecule are important determinants of binding at the sigma site. Keywords: Crystal structure; cubanes; neuroactivity; pharmaceuticals; sigma binding site.

Small angle X-ray scattering (SAXS) was applied to the binding of the immunosuppressant drug cyclasporin-A to the protein calmodulin. Guinier analysis of the SAXS profiles yielded a radius of gyration, Rg, of 19.7 ± 0.3 Å for the native protein and 16.9 ± 0.3 Å for the drug/protein complex. Maximum entropy (maxent) methods of data analysis were used to calculate the distance distribution function, p(r). From this analysis, the R_g for the native protein is 20.9 ± 0.1 Å and that for the complex 16.7 ± 0.1 Å. The measured SAXS profiles and the derived p(r) for calmodulin agree with profiles calculated from the crystallographic structure of calmodulin. Major structural changes are induced in calmodulin on binding cyclosporin-A. A model consistent with the observed scattering profiles is an ellipsoid with major axes 55 and 36 Å. Molecular modeling of the calmodulin molecule suggests that bond rotation in the flexible α-helix linker region produces models consistent with the above observations. Copyright 1994, 1999 Academic Press

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AbstractFPONeutron scattering techniques have been an active component of the Australian scientific research community for the past three decades, commencing soon after the High Flux Australian Reactor (HIFAR) started routine operation in 1968. HIFAR, a 10MW(th) multi purpose facility of modest performance (maximum neutron flux 10IJcm-sec-l), provides the only neutron source in the country suitable for neutron scattering. HIFAR (Figure 1) is a DIDO class reactor operated by the Australian Nuclear Science and Technology Organisation (ANSTO), a government research organization with the mission to “ensure that its research, technology transfer, commercial and training activities in nuclear science and associated technologies will advance Australia's innovation, international competitiveness and environmental and health management” (see our Web page: http://www.ansto.gov.au).

Four N-substituted amide derivatives of sorbic acid and two amine salts of sorbic acid were synthesized and tested for fungistatic activity against Microsporum canis, Trichophyton mentagrophytes, and Candida albicans. The compounds were tested by the disk-plate method initially and then followed by incorporation into polyethylene glycol ointment USP and tested on Sabouraud's dextrose agar culture plates. Results were compared with undecylenic acid and sorbic acid controls. The disk-plate method showed activity greater than sorbic acid, but less than undecylenic acid only for N-methylfurfurylsorbamide when tested against Microsporum canisand Trichophyton mentagrophytes. When incorporated into ointment, both N-methylfurfurylsorbamide and t-octylamine sorbate showed activity comparable to the controls against Microsporum canisand Trichophyton mentagrophytes. None of the new compounds were as effective against Candida albicansas were the controls.

The compound [Pd(CH3)(PPh3)(N–O)] (N–O represents pyridine-2-carboxylato (pyca)) has been synthesized and the structure determined. The compound crystallized in the monoclinic space group P21/c, a 8.4844(9), b 12.845(2), c 19.690(3) Å, b 92.09(1)˚, V 2144.4(5) Å 3 , Z 4, and was refined to an R value of 0.022 on 3551 F. The structure had a distorted square-planar geometry in which the donor nitrogen and phosphine ligands are trans. Keywords. Palladium, picolinic acid; X-ray crystal structure.

The phytochemical investigation of a northwest herb, Galium triflorum, is presented including a study of the physical and chemical properties and methods of isolation of asperuloside, a glucoside common to many members of the Rubiaceae. The hypotensive effects of asperuloside and an aqueous extract of the plant were tested pharmacologically. The results obtained are presented.

The article discusses the androgyne myth in European art. Examples of references to such myth can be found in the 1930s European art. This shows the development of androgyne from the limited hermaphrodite image in the late 19th century to one that is fundamental to surrealism. It notes that all important sources for androgyny theme can be seen in art periodicals in the 1930s such as "Cahiers d' Art" or "Minotaure," which contains articles on primitive ethnology, psychoanalysis and alchemy.

The LD50of pantetheine in mice was found to lie between 5 and 7.5 g/kg body weight. General depression, and eventual death were observed in animals after administration of high dosages of the compound. Intraperitoneal injections of pantetheine at 0.2 g/kg body weight continuously for 10 weeks did not affect growth of mice.