Optimal geometry of transportation networks.

Motivated by the shape of transportation networks such as subways, we consider a distribution of points in the plane and ask for the network G of given length L that is optimal in a certain sense. In the general model, the optimality criterion is to minimize the average (over pairs of points chosen independently from the distribution) time to travel between the points, where a travel path consists of any line segments in the plane traversed at slow speed and any route within the subway network traversed at a faster speed. Of major interest is how the shape of the optimal network changes as L increases.

True scale-invariant random spatial networks.

Some aspects of real-world road networks seem to have an approximate scale invariance property, motivating study of mathematical models of random networks whose distributions are exactly invariant under Euclidean scaling. This requires working in the continuum plane, so making a precise definition is not trivial. We introduce an axiomatization of a class of processes we call scale-invariant random spatial networks, whose primitives are routes between each pair of points in the plane.

Dimerization of β-tryptase inhibitors, does it work for both basic and neutral P1 groups?

The tetrameric folding of β-tryptase and the pair-wise distribution of its substrate binding sites offer a unique opportunity for development of inhibitors that span two adjacent binding sites. A series of dimeric inhibitors with two basic P1 moieties was discovered using this design strategy and exhibited tight-binder characteristics. Using the same strategy, an attempt was made to design and synthesize dimeric inhibitors with two neutral-P1 groups in hope to exploit the dimeric binding mode to achieve a starting point for further optimization.

Metal-organic frameworks for the storage and delivery of biologically active hydrogen sulfide.

Hydrogen sulfide is an extremely toxic gas that is also of great interest for biological applications when delivered in the correct amount and at the desired rate. Here we show that the highly porous metal-organic frameworks with the CPO-27 structure can bind the hydrogen sulfide relatively strongly, allowing the storage of the gas for at least several months. Delivered gas is biologically active in preliminary vasodilation studies of porcine arteries, and the structure of the hydrogen sulfide molecules inside the framework has been elucidated using a combination of powder X-ray diffraction and pair distribution function analysis.

An ionothermally prepared S = 1/2 vanadium oxyfluoride kagome lattice.

Frustrated magnetic lattices offer the possibility of many exotic ground states that are of great fundamental importance. Of particular significance is the hunt for frustrated spin-1/2 networks as candidates for quantum spin liquids, which would have exciting and unusual magnetic properties at low temperatures. The few reported candidate materials have all been based on d(9) ions.

Protecting group and switchable pore-discriminating adsorption properties of a hydrophilic-hydrophobic metal-organic framework.

Formed by linking metals or metal clusters through organic linkers, metal-organic frameworks are a class of solids with structural and chemical properties that mark them out as candidates for many emerging gas storage, separation, catalysis and biomedical applications. Important features of these materials include their high porosity and their flexibility in response to chemical or physical stimuli. Here, a copper-based metal-organic framework has been prepared in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during synthesis to produce a solid with two different channel systems, lined by hydrophilic and hydrophobic surfaces, respectively.

Five statistical questions about the tree of life.

Stochastic modeling of phylogenies raises five questions that have received varying levels of attention from quantitatively inclined biologists. 1) How large do we expect (from the model) the ratio of maximum historical diversity to current diversity to be? 2) From a correct phylogeny of the extant species of a clade, what can we deduce about past speciation and extinction rates? 3) What proportion of extant species are in fact descendants of still-extant ancestral species, and how does this compare with predictions of models? 4) When one moves from trees on species to trees on sets of species (whether traditional higher order taxa or clades within PhyloCode), does one expect trees to become more unbalanced as a purely logical consequence of tree structure, without signifying any real biological phenomenon? 5) How do we expect that fluctuation rates for counts of higher order taxa should compare with fluctuation rates for number of species? We present a mathematician's view based on an oversimplified modeling framework in which all these questions can be studied coherently.

A new chain structure: catena-poly[4,4'-(ethane-1,2-diyl)dipyridinium bis[[aquadifluoridooxidovanadate]-mu-fluorido]].

The title compound, {(C(12)H(12)N(2))[V(2)F(6)O(2)(H(2)O)(2)]}(n), features a novel extended-chain moiety, [VOF(2)F(2/2)(H(2)O)](n), comprising trans vertex-connected VOF(4)(H(2)O) octahedra. The octahedra themselves show the characteristic distortion due to the off-centering of the V(4+) ion, such that a short terminal V=O bond and an elongated trans V-OH(2) bond are present. Hydrogen bonding from the water molecules to terminal F atoms in adjacent chains generates associated chain dimers, which are loosely linked into sheets via additional hydrogen bonding involving the organic moieties.

"If the land is healthy ... it makes the people healthy": the relationship between caring for Country and health for the Yorta Yorta Nation, Boonwurrung and Bangerang Tribes.

This article reports on research undertaken with members of three Indigenous groups in Victoria, Australia, to explore the health and wellbeing implications of caring for Country (defined as having knowledge, sense of responsibility and inherent right to be involved in the management of traditional lands). The research findings provide a better understanding of this key determinant of the health and wellbeing of Indigenous people in the context of public health where there are few existing published studies assessing this relationship. Thirteen traditional custodians(1) and local Indigenous environmental workers were interviewed.

Stochastic models for phylogenetic trees on higher-order taxa.

Simple stochastic models for phylogenetic trees on species have been well studied. But much paleontology data concerns time series or trees on higher-order taxa, and any broad picture of relationships between extant groups requires use of higher-order taxa. A coherent model for trees on (say) genera should involve both a species-level model and a model for the classification scheme by which species are assigned to genera.

Hydrothermal chemistry of oligomeric vanadium oxyfluorides.

Nine new vanadium oxyfluorides, containing ten different oligomeric vanadium (oxy)fluoride anions have been prepared by solvothermal synthesis in water-ethylene glycol and using organic cations as co-crystallising agents. Crystal structures are reported for each. Amongst the ten structure types, five represent previously unobserved moieties, including one monomeric unit (cis-[VOF4(H2O)]2-), two dimers ([V2O2F6(H2O)2]2- and [V2O2F8]4-) and two tetramers (both isomers of composition [V4O4F14]6-).

Hydrothermal vanadium fluoride chemistry: four new V3+ chain structures.

An exploratory study of the hydrothermal chemistry of vanadium in HF solutions has resulted in the preparation of four new vanadium (III) fluorides with chainlike structural motifs. [NH4]2[VF5] (1) and [C2N2H10][VF5] (2) feature infinite chains of trans corner-sharing VF4F2/2 octahedra, [C4N2H6][VF5].H2O (3) has cis corner-sharing [VF4F2/2]infinity chains, and [C10N2H8][VF3] (4) has trans corner-sharing [VF2F2/2]infinity chains bridged into sheets by the 4,4'-bipy linker.

Novel vanadium(IV) oxyfluorides with 'spin-ladder'-like structures, and their relationship to (VO)2P2O7.

Three novel vanadium(IV) oxyfluorides have been prepared by hydrothermal synthesis. All three materials feature 'ladder'-like chains of edge- and corner-sharing V(O/F) octahedra, topologically similar to those in (VO)2P2O7. CsVOF3 and RbVOF3 are isostructural, whereas in (bpeH2)1/2[VOF3] (bpe = trans-1,2-bis(4-pyridyl)-ethylene) inclusion of the organic structure-directing agent affects both the conformation of the ladders and their packing within the unit cell.

Role of cathepsin S-dependent epithelial cell apoptosis in IFN-gamma-induced alveolar remodeling and pulmonary emphysema.

Th1/Tc1 inflammation and remodeling responses characterized by tissue atrophy and destruction frequently coexist in human diseases and disorders. However, the mechanisms that are used by Th1/Tc1 cytokines, like IFN-gamma, to induce these responses have not been defined. To elucidate the mechanism(s) of IFN-gamma-induced tissue remodeling and destruction, we characterized the pathway that lung-targeted, transgenic IFN-gamma uses to induce alveolar remodeling in a murine pulmonary emphysema modeling system.

Phosphorus-nitrogen-phosphorus ligands: cooperative effects between nitrogen and phosphorus substituents on catalytic activity.

A new generation of PNP compounds bearing different diarylphosphine groups were prepared and used as ligands in palladium-catalysed Suzuki cross-coupling reactions. Rates of oxidative addition of iodobenzene to (PNP)Pd[0] complexes were measured using UV spectroscopy. Synergistic effects between the N- and P- substituents were identified and correlated in redox and catalytic chemistry.

A general strategy for the diastereoselective synthesis of 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans.

A strategy for the stereoselective synthesis of all the possible diastereoisomers of the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane (furofuran) lignans from a single dihydrofuran precursor is described.

Scaling and universality in continuous length combinatorial optimization.

We consider combinatorial optimization problems defined over random ensembles and study how solution cost increases when the optimal solution undergoes a small perturbation delta. For the minimum spanning tree, the increase in cost scales as delta2. For the minimum matching and traveling salesman problems in dimension d >/= 2, the increase scales as delta3; this is observed in Monte Carlo simulations in d = 2, 3, 4 and in theoretical analysis of a mean-field model.

Potent small molecule inhibitors of spleen tyrosine kinase (Syk).

A series of oxindoles demonstrating inhibition of the phosphorylation of biotinylated substrates of Syk and IgE/Fc epsilon RI triggered basophil cell degranulation has been identified. A study of the SAR around sulfonamide 31 (IC(50)=5 nM, EC(50)=1400 nM) is discussed. The modest cellular activity representative of the sulfonamide series was overcome when the Polar Surface Area was lowered to <110 A(2), leading to the identification of amide 32 (IC(50)=145 nM, EC(50)=100 nM).

Mapping the kinase domain of Janus Kinase 3.

The utilization and impact of parallel synthesis on lead exploration around initial hit oxindole (1) are described. The emergent SAR, analogue design and functional impact will also be detailed.

A short synthesis of (+/-)-epiasarinin.

[reaction: see text] Epiasarinin, an endo-endo furofuran, has been synthesized from piperonal via a five-step route with good stereocontrol. The sequence involves Darzens condensation, alkenyl epoxide-dihydrofuran rearrangement, and a Lewis acid mediated cyclization.