On Three-Dimensional Space Groups

An entirely new and independent enumeration of the crystallographic space groups is given, based on obtaining the groups as fibrations over the plane crystallographic groups, when this is possible. For the 35 ``irreducible'' groups for which it is not, an independent method is used that has the advantage of elucidating their subgroup relationships. Each space group is given a short ``fibrifold name'' which, much like the orbifold names for two-dimensional groups, while being only specified up to isotopy, contains enough information to allow the construction of the group from the name.Comment: 26 pages, 8 figure

Preparation and Characterization of Photoactive Antimicrobial Graphitic Carbon Nitride (g-C\u3csub\u3e3\u3c/sub\u3eN\u3csub\u3e4\u3c/sub\u3e) Films

Photoactive films derived from nanostructured samples of the metal-free, intermediate band gap semiconductor graphitic carbon nitride (ns-g-C3N4) have been synthesized and characterized for their particle properties and antimicrobial activity. Physical characterization reveals that these materials are composed of discrete nanoparticles whose dimensions range from 200 nm to 700 nm. Investigation of the photochemical reactivity of ns-g-C3N4 using coumarin-3- carboxylic acid (3-CCA) indicates that this material produces reactive oxygen species (ROS) under visible radiation. When irradiated with 0.31J visible light, ns-g-C3N4-based materials reduced the viability of both gram-negative Escherichia coli O157:H7 and gram-positive Staphylococcus aureus by approximately 50%. Nearly complete inactivation of both strains of microorganisms was achieved upon administration of a 0.62J dose of visible radiation. Importantly, no biocidal activity was observed for non-irradiated samples, indicating that the g-C3N4-derived films are not inherently toxic in the absence of visible light. The results of this study suggest that materials and, by extention, films and coatings derived from g-C3N4 may present a novel route for controlling pathogenic microorganisms on surfaces in the environment, and could be useful in reducing incidents of hospital-acquired infections

1,4,5,8-Naphthalene Tetracarboxylate Dianhydride/g-C\u3csub\u3e3\u3c/sub\u3eN\u3csub\u3e4\u3c/sub\u3e van der Waals Heterojunctions Exhibit Enhanced Photochemical H\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e Production and Antimicrobial Activity

Organic semiconductors, including graphitic carbon nitride (g-C3N4, CN), represent an important class of materials for the development of novel antimicrobial or biomedical technologies. Of principal interest is the ability of these materials to catalyze the reduction of elemental oxygen to generate reactive oxygen species (ROS), including hydrogen peroxide (H2O2). Here, we describe the fabrication of photoactive van der Waals heterojunctions incorporating 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA) and CN. The composite heterojunction systems were characterized by a combination of physical (TEM, SEM, pXRD), spectroscopic (FT-IR, XPS, DRUV, photoluminescence, TCSPC) and kinetic experiments. Electronic interactions between the two components of the heterojunction increase the rate of photochemical production of H2O2 from elemental oxygen by 410%, relative to samples of pure CN. Mechanistic analysis reveals that interaction of NTCDA with the surface of CN modifies the mechanism of H2O2 formation in the heterojunction photocatalysts. The photochemical production of H2O2 by irradiation of the most active heterojunction composition is sufficient to reduce the viability of E. coli O157:H7, S. aureus and Ps. aeruginosa PAO1 by 99%. Importantly, H2O2 production by the NTCDA/CN heterojunctions suppresses Ps. aeruginosa biofilm formation, even at light exposure doses that had a lesser impact on overall planktonic cell growth

A pilot randomised controlled trial of the Peer Tree digital intervention targeting loneliness in young people: a study protocol

Background Young people are vulnerable to experiencing problematic levels of loneliness which can lead to poor mental health outcomes. Loneliness is a malleable treatment target and preliminary evidence has shown that it can be addressed with digital platforms. Peer Tree is a strength-based digital smartphone application aimed at reducing loneliness. The study aim is to reduce loneliness and assess the acceptability, usability, and feasibility of Peer Tree in young people enrolled at university. Methods This will be a pilot randomised controlled trial (RCT) comparing a strength-based digital smartphone application (Peer Tree) with a control condition. Forty-two young people enrolled at university will be recruited for this pilot RCT. Participants with suicidal ideation or behaviours, acute psychiatric symptoms in the past month, or a current diagnosis of a mood or social anxiety disorder will be excluded. Allocation will be made on a 1:1 ratio and will occur after the initial baseline assessment. Assessments are completed at baseline, at post-intervention, and at follow-up. Participants in the control condition complete the same three assessment sessions. The primary outcome of the study will be loneliness. Depression, social anxiety, quality of life, acceptability, usability, feasibility, and safety of Peer Tree will also be measured as secondary outcomes. Discussion This trial will report the findings of implementing Peer Tree, a smartphone application aimed at reducing loneliness in university students. Findings from this trial will highlight the initial efficacy, acceptability, and feasibility of using digital positive psychology interventions to reduce subthreshold mental health concerns. Findings from this trial will also describe the safety of Peer Tree as a digital tool. Results will contribute evidence for positive psychology interventions to address mental ill-health. Trial registration Australian New Zealand Clinical Trial Registry ACTRN12619000350123. Registered on 6 March 202

The Isotropy of Compact Universes

We discuss the problem of the stability of the isotropy of the universe in the space of ever-expanding spatially homogeneous universes with a compact spatial topology. The anisotropic modes which prevent isotropy being asymptotically stable in Bianchi-type $VII_h$ universes with non-compact topologies are excluded by topological compactness. Bianchi type $V$ and type $VII_h$ universes with compact topologies must be exactly isotropic. In the flat case we calculate the dynamical degrees of freedom of Bianchi-type $I$ and $VII_0$ universes with compact 3-spaces and show that type $VII_0$ solutions are more general than type $I$ solutions for systems with perfect fluid, although the type $I$ models are more general than type $VII_0$ in the vacuum case. For particular topologies the 4-velocity of any perfect fluid is required to be non-tilted. Various consequences for the problems of the isotropy, homogeneity, and flatness of the universe are discussed.Comment: 22 pages in LaTeX2e with the amsmath packag

Compact Hyperbolic Extra Dimensions: Branes, Kaluza-Klein Modes and Cosmology

We reconsider theories with low gravitational (or string) scale M_* where Newton's constant is generated via new large-volume spatial dimensions, while Standard Model states are localized to a 3-brane. Utilizing compact hyperbolic manifolds (CHM's) we show that the spectrum of Kaluza-Klein (KK) modes is radically altered. This allows an early universe cosmology with normal evolution up to substantial temperatures, and completely negates the constraints on M_* arising from astrophysics. Furthermore, an exponential hierarchy between the usual Planck scale and the true fundamental scale of physics can emerge with only order unity coefficients. The linear size of the internal space remains small. The proposal has striking testable signatures.Comment: 4 pages, no figure

Activity of the DNA minor groove cross-linking agent SG2000 (SJG-136) against canine tumours

BACKGROUND: Cancer is the leading cause of death in older dogs and its prevalence is increasing. There is clearly a need to develop more effective anti-cancer drugs in dogs. SG2000 (SJG-136) is a sequence selective DNA minor groove cross-linking agent. Based on its in vitro potency, the spectrum of in vivo and clinical activity against human tumours, and its tolerability in human patients, SG2000 has potential as a novel therapeutic against spontaneously occurring canine malignancies. RESULTS: In vitro cytotoxicity was assessed using SRB and MTT assays, and in vivo activity was assessed using canine tumour xenografts. DNA interstrand cross-linking (ICL) was determined using a modification of the single cell gel electrophoresis (comet) assay. Effects on cell cycle distribution were assessed by flow cytometry and measurement of γ-H2AX by immunofluorescence and immunohistochemistry. SG2000 had a multi-log differential cytotoxic profile against a panel of 12 canine tumour cell lines representing a range of common tumour types in dogs. In the CMeC-1 melanoma cell line, DNA ICLs increased linearly with dose following a 1 h treatment. Peak ICL was achieved within 1 h and no removal was observed over 48 h. A relationship between DNA ICL formation and cytotoxicity was observed across cell lines. The formation of γ-H2AX foci was slow, becoming evident after 4 h and reaching a peak at 24 h. SG2000 exhibited significant anti-tumour activity against two canine melanoma tumour models in vivo. Anti-tumour activity was observed at 0.15 and 0.3 mg/kg given i.v. either once, or weekly x 3. Dose-dependent DNA ICL was observed in tumours (and to a lower level in peripheral blood mononuclear cells) at 2 h and persisted at 24 h. ICL increased following the second and third doses in a repeated dose schedule. At 24 h, dose dependent γ-H2AX foci were more numerous than at 2 h, and greater in tumours than in peripheral blood mononuclear cells. SG2000-induced H2AX phosphorylation measured by immunohistochemistry showed good correspondence, but less sensitivity, than measurement of foci. CONCLUSIONS: SG2000 displayed potent activity in vitro against canine cancer cell lines as a result of the formation and persistence of DNA ICLs. SG2000 also had significant in vivo antitumour activity against canine melanoma xenografts, and the comet and γ-H2AX foci methods were relevant pharmacodynamic assays. The clinical testing of SG2000 against spontaneous canine cancer is warranted. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12917-015-0534-2) contains supplementary material, which is available to authorized users

Statistical-Thermodynamic Model for Light Scattering from Eye Lens Protein Mixtures

We model light-scattering cross sections of concentrated aqueous mixtures of the bovine eye lens proteins γB- and α-crystallin by adapting a statistical-thermodynamic model of mixtures of spheres with short-range attractions. The model reproduces measured static light scattering cross sections, or Rayleigh ratios, of γB-α mixtures from dilute concentrations where light scattering intensity depends on molecular weights and virial coefficients, to realistically high concentration protein mixtures like those of the lens. The model relates γB-γB and γB-α attraction strengths and the γB-α size ratio to the free energy curvatures that set light scattering efficiency in tandem with protein refractive index increments. The model includes (i) hard-sphere α-α interactions, which create short-range order and transparency at high protein concentrations, (ii) short-range attractive plus hard-core γ-γ interactions, which produce intense light scattering and liquid-liquid phase separation in aqueous γ-crystallin solutions, and (iii) short-range attractive plus hard-core γ-α interactions, which strongly influence highly non-additive light scattering and phase separation in concentrated γ-α mixtures. The model reveals a new lens transparency mechanism, that prominent equilibrium composition fluctuations can be perpendicular to the refractive index gradient. The model reproduces the concave-up dependence of the Rayleigh ratio on α/γ composition at high concentrations, its concave-down nature at intermediate concentrations, non-monotonic dependence of light scattering on γ-α attraction strength, and more intricate, temperature-dependent features. We analytically compute the mixed virial series for light scattering efficiency through third order for the sticky-sphere mixture, and find that the full model represents the available light scattering data at concentrations several times those where the second and third mixed virial contributions fail. The model indicates that increased γ-γ attraction can raise γ-α mixture light scattering far more than it does for solutions of γ-crystallin alone, and can produce marked turbidity tens of degrees celsius above liquid-liquid separation