Anhydrous Proton Conduction Through a Chemically Robust Electrolyte Enabling a High-Temperature Non-Precious Metal Catalyzed Fuel Cell

Fuel cells offer great promise for portable electricity generation, but their use is currently limited by their low durability, excessive operating temperatures, and expensive precious metal electrodes. It is therefore essential to develop fuel cell systems that can perform effectively using more robust electrolyte materials, at reasonable temperatures, with lower-cost electrodes. Recently, proton exchange membrane fuel cells have attracted attention due to their generally favorable chemical stability and quick start-up times. However, in most membrane materials, water is required for proton conduction, severely limiting operational temperatures. Here, for the first time it is demonstrated that when acidified, PAF-1 can conduct protons at high temperatures, via a unique framework diffusion mechanism. It shows that this acidified PAF-1 material can be pressed into pellets with high proton conduction properties even at high temperatures and pellet thickness, highlighting the processibility, and ease of use of this material. Furthermore, a fuel cell is shown with high power density output is possible using a non-precious metal copper electrode. Acid-doped PAF-1 therefore represents a significant step forward in the potential for a broad-purpose fuel cell due to it being cheap, robust, efficient, and easily processible.

Photo-Modulating CO2 Uptake of Hypercross-linked Polymers Upcycled from Polystyrene Waste

Incorporating photo-switches into skeletal structures of microporous materials or as guest molecules yield photo-responsive materials for low-energy CO₂ capture but at the expense of lower CO₂ uptake. Here, we overcome this limitation by exploiting trans-cis photoisomerization of azobenzene loaded into the micropores of hypercross-linked polymers (HCPs) derived from waste polystyrene. Azobenzene in HCP pores reduced CO₂ uptake by 19 %, reaching 37.7 cm³  g^-1 , but this loss in CO₂ uptake was not only recovered by trans-cis photoisomerization of azobenzene, but also increased by 22 %, reaching 56.9 cm³  g^-1 , when compared to as-prepared HCPs. Computational simulations show that this increase in CO₂ uptake is due to photo-controlled increments in 10-20 Å micropore volume, i. e., adsorption sites and a photo-reversible positive dipole moment. Irradiating these HCPs with visual-range light reverted CO₂ uptake to 33 cm³  g^-1 . This shows that it is feasible to recycle waste polystyrene into advanced materials for low-energy carbon capture.

Artificial synthesis of covalent triazine frameworks for local structure and property determination

Here we show an 'artificial synthesis' method for covalent triazine framework (CTF) materials, enabling localised structural features to be incorporated that result directly from the acid-catalysed synthetic protocol that would otherwise not be captured. This advancement will enable prediction and design of new CTF materials with targeted properties.

Rationalising the influence of solvent choice on the porosity of conjugated microporous polymers

Conjugated microporous polymers (CMPs) synthesised in different solvents give different surface areas dependent on the solvent choice. No one solvent results in a high surface area across a range of different CMP materials. Here, we present an investigation into how the porosity of CMPs is affected by solvent polarity. It is seen that the trends differ depending on the respective monomer dipole moments and whether hydrogen bonding groups are present in the monomers and are able to interact with the respective solvent via hydrogen bonding. It is believed that this methodology could be used to influence future materials design of both structure and synthesis strategy.

Artificial Synthesis of Conjugated Microporous Polymers via Sonogashira-Hagihara Coupling

Amorphous network materials are becoming increasingly important with applications, for example, as supercapacitors, battery anodes, and proton conduction membranes. The design of these materials is hampered by the amorphous nature of the structure and sensitivity to synthetic conditions. Here, we show that through artificial synthesis, fully mimicking the catalytic formation cycle, and full synthetic conditions, we can generate structural models that can fully describe the physical properties of these amorphous network materials. This opens up pathways for the rational design where complex structural influences, such as the solvent and catalyst choice, can be taken into account.

Formation mechanism of ultra porous framework materials

Understanding the formation mechanism of ultra porous framework materials may lead to insights into strategies for the design and synthesis of novel ultra porous materials or for the increased surface area of known materials.

Modelling analysis of the structure and porosity of covalent triazine-based frameworks

We assess structure directing effects and potential origins of structural order and formulate basic rules relating building block structure to porosity properties.

Novel self-assembled 2D networks based on zinc metal ion co-ordination: synthesis and comparative study with 3D networks

Novel 2-D supramolecular networks were made by metal-ion coordination, and their properties compared with similar 3-D networks.

Porous organic cages

Porous materials are important in a wide range of applications including molecular separations and catalysis. We demonstrate that covalently bonded organic cages can assemble into crystalline microporous materials. The porosity is prefabricated and intrinsic to the molecular cage structure, as opposed to being formed by non-covalent self-assembly of non-porous sub-units. The three-dimensional connectivity between the cage windows is controlled by varying the chemical functionality such that either non-porous or permanently porous assemblies can be produced. Surface areas and gas uptakes for the latter exceed comparable molecular solids. One of the cages can be converted by recrystallization to produce either porous or non-porous polymorphs with apparent Brunauer-Emmett-Teller surface areas of 550 and 23 m2 g(-1), respectively. These results suggest design principles for responsive porous organic solids and for the modular construction of extended materials from prefabricated molecular pores.

Control of porosity geometry in amino acid derived nanoporous materials

Substitution of the pillaring ligand in the homochiral open-framework [Ni(2)(L-asp)(2)(bipy)] by extended bipy-type ligands leads to a family of layer-structured, homochiral metal-organic frameworks. The 1D channel topology can be modified by the nature of the organic linker, with shape, cross-section and the chemical functionality tuneable. In addition, the volume of these channels can be increased by up to 36 % compared to the parent [Ni(2)(L-asp)(2)(bipy)]. The linker 1,4-dipyridylbenzene (3rbp) gives access to a new layered homochiral framework [Ni(2)(L-asp)(2)(3rbp)] with channels of a different shape. In specific cases, non-porous analogues with the linker also present as a guest can be activated to give porous materials after sublimation. Their CO(2) uptake shows an increase of up to 30 % with respect to the parent [Ni(2)(L-asp)(2)(bipy)] framework.

Effects of dioxin, an environmental pollutant, on mouse blastocyst development and apoptosis

OBJECTIVE

To evaluate the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin) on mouse embryo development and apoptosis.

DESIGN

Controlled animal study.

SETTING

Academic research environment.

ANIMAL(S)

Female mice (CB6F1) at 3 to 6 weeks of age and proven breeders (C578B46).

INTERVENTION(S)

Mouse embryos were obtained at the morula stage and cultured to the blastocyst stage in a pharmacologic dose of TCDD (3.1 microM) or a control medium. The morphology was assessed, and staining for apoptosis was performed. Immunohistochemistry for the presence of aromatic hydrocarbon receptor (AhR) was performed in another set of morula-stage embryos.

MAIN OUTCOME MEASURE(S)

The number of embryos developing from the morula to the blastocyst stage and number of apoptotic blastomeres in control vs. TCDD culture conditions.

RESULT(S)

No statistically significant differences were observed in the percentage of embryos reaching the blastocyst stage: 80.9% (115 of 142) in the TCDD-treated group, vs. 82.9% (121 of 146) in the control group. There was also no difference in the degree of apoptosis: 22.6 +/- 7.3% apoptotic cells (TCDD) vs. 25.3 +/- 9.7% (controls). Staining indicated the slight presence of aromatic hydrocarbon receptor in the morula-stage mouse embryos.

CONCLUSION(S)

TCDD at 3.1 microM did not alter the development of early mouse morula to blastocysts and did not significantly induce apoptosis in vitro.

Peripheral blood lymphocyte transformation in response to human thyroid fractions in patients with Graves' hyperthyroidism and ophthalmopathy

Peripheral blood lymphocyte (PBL) transformation in response to human thyroid fractions was carried out in patients with Graves' hyperthyroidism and ophthalmopathy. The fractions used were, an extract, a soluble (cytosol) fraction, and membranes prepared by differential centrifugation at (i) 6500 x g (mitochondria), (ii) 10 000 x g (plasma membranes as used in the radioreceptor assay for thyroid stimulating antibody (TSAb) and (iii) 40 000 x g (microsomes). Results were expressed as stimulation indices (SI). Mean SI for patients were significantly increased compared with those for normals for cytosol and mitochondria but not the other fractions. Taking the upper limit of normal as mean +2 SD for normal subjects for each fraction, positive tests were found in 12 of 35 patients tested. This was in response to extract in 3 of 32 patients, to the soluble fraction in 10 of 31 patients, to mitochondria in 2 of 13 patients, to plasma membranes in 1 of 33 patients, and to microsomes in 1 of 27 patients. Positive tests were associated with hyperthyroidism but not ophthalmopathy.

In vitro production of thyroid-binding antibodies by peripheral blood lymphocytes from patients with Graves' disease: nonspecific responses associated with culture supernatant proteins

Peripheral blood lymphocytes from patients with Graves' disease were cultured for 7 days with mitogens (phytohemagglutinin, Concanavalin A, protein A), or specific antigen (thyroid membranes), in an attempt to produce thyroid-binding antibodies (TBAb) in vitro. TBAb was measured in culture supernatants using a sensitive radioreceptor assay. Mean TBAb indices of mitogen or antigen-stimulated cultures did not differ significantly from those of unstimulated cultures for either patients or normal subjects. Although TBAb indices of less than 0.70, which are generally considered positive for serum TBAb, were demonstrated in a small proportion of individual tests of supernatants from patients with Graves' disease, low indices were also found in tests from normal subjects. One cause of such nonspecific responses was found to be culture infection. The factor associated with positive responses in infected cultures was unlikely to be an immunoglobulin since TBAb-like activity was not detected in globulins isolated by DEAE + -Sephadex chromatography, which isolates only IgG and IgA, and the activity was not neutralized by anti-IgG serum. The possible ways of improving the culture system for in vitro TBAb production and the significance of nonspecific responses in the radioreceptor assay are discussed.

Studies of immunoreactivity to human lacrimal gland fractions in patients with ophthalmic Graves' disease

In vitro evidence for immunoreactivity against human lacrimal gland fractions was sought in patients with ophthalmic Graves' disease. There was no significant increase in interstitial lymphoid tissue on lacrimal gland biopsy. Serum antibodies against lacrimal fractions were not detected using the indirect immunofluorescent technique. Using the tanned cell hemagglutination test with lacrimal antigen, antibodies were detected in 2 of 15 patients with eye disease, 2 of 15 hyperthyroid patients without eye disease, and 2 of 20 normal subjects. Macrophage inhibitory factor (MIF) production in response to human lacrimal extract was not demonstrated in any of 11 patients with eye disease tested. On the other hand, MIF was demonstrated in 2 of 10 patients with Graves' disease selected for absence of eye disease. Significant peripheral blood lymphocyte transformation in response to human lacrimal extract, or a soluble or membrane fraction, was demonstrated in 9 of 22 patients tested; in 6 of 21 patients to extract, in 3 of 21 patients to a soluble fraction and in 7 of 10 patients to a membrane fraction. The possible significance of lacrimal gland inflammation and role(s) in the pathogenesis of ophthalmic Graves' disease are discussed.