Tuning (Anti)Aromaticity: Variations on the [8]-Circulene Framework.

Optoelectronic properties of organic molecules are underpinned by delocalisation and delocalisability of π-electrons. These properties are sensitive to small changes in electron count, whether achieved by heteroatom substitution or redox chemistry. One measure of the delocalisability of π-electrons is the current induced by an external magnetic field, which is diagnostic of (anti)aromaticity. The ab initio ipsocentric method is used here to model diverse ring-current patterns in the family of [8]-circulenes based on tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP), in different charge states, with disjoint hetero-atom substitution, and with CC units systematically replaced by BN pairs. Maps calculated at the CHF/CTOCD-DZ2/6-31G** level reveal that these modifications of the TCPTP framework access the full range of possibilities for current from concentric global circulations (typically counter rotating) to full (non-aromatic) localisation. In the ipsocentric approach, induced current density is partitioned into robust orbital contributions that obey selection rules based on orbital symmetry, energy and nodal character. The selection rules are applied here to interpret current-density and exploit insights gained from simpler models to suggest design strategies for fine-tuning of π-delocalisability (aromaticity and antiaromaticity) in macrocyclic frameworks.

Scaling-up Child and Youth Mental Health Services: Assessing Coverage of a County-Wide Prevention and Early Intervention Initiative During One Fiscal Year.

PURPOSE: In the U.S., the percentage of youth in need of evidence-based mental health practices (EBPs) who receive them (i.e., coverage rate) is low. We know little about what influences coverage rates. In 2010, the Los Angeles County Department of Mental Health (LACDMH) launched a reimbursement-driven implementation of multiple EBPs in youth mental health care. This study examines two questions: (1) What was the coverage rate of EBPs delivered three years following initial implementation? (2) What factors are associated with the coverage rates? METHODS: To assess coverage rates of publicly insured youth, we used LACDMH administrative claims data from July 1, 2013 to June 30, 2014 and estimates of the size of the targeted eligible youth population from the 2014 American Community Survey (ACS). The unit of analysis was clinic service areas (n = 254). We used Geographic Information Systems and an OLS regression to assess community and clinic characteristics related to coverage. RESULTS: The county coverage rate was estimated at 17%, much higher than national estimates. The proportion of ethnic minorities, individuals who are foreign-born, adults with a college degree within a geographic area were negatively associated with clinic service area coverage rates. Having more therapists who speak a language other than English, providing care outside of clinics, and higher proportion of households without a car were associated with higher coverage rates. CONCLUSION: Heterogeneity in municipal mental health record type and availability makes it difficult to compare the LACDMH coverage rate with other efforts. However, the LACDMH initiative has higher coverage than published national rates. Having bilingual therapists and providing services outside the clinic was associated with higher coverage. Even with higher coverage, inequities persisted.

The impact of responsible fatherhood programs on parenting, psychological well-being, and financial outcomes: A randomized controlled trial.

The objective of this study was to examine differences in parenting, psychological well-being, and economic outcomes between fathers receiving two different programs offered by Fathers & Families Support Center for economically disadvantaged fathers: (a) Family Formation (FF), a 6-week/240-h program focused on economic stability/mobility, responsible fatherhood, and healthy relationships, with case management and legal services; (b) Economic Stability (ES), a 4-week/80-h program focused only on economic stability with limited case management and legal services. A randomized controlled trial (RCT) was used to compare fathers in FF (n = 350) vs. ES (n = 342). Surveys were administered at enrollment and 3- and 12-months postintervention. Linear and generalized linear mixed models were used to assess changes in program outcomes over time and across study groups. Four hundred and eighty-two fathers responded to either follow-up survey (251 FF, 231 ES). Nearly all (98%) were non-white (93% Black, 5% other/mixed race) and were on average 34 years old. Approximately 46% attended ≥75% of program sessions (FF 48% vs. ES 44%). Both FF and ES groups experienced improvements in parenting, psychological well-being, and financial outcomes after the programs, but changes in outcomes over time did not differ significantly by program. The lack of difference in outcomes between fathers in FF and ES groups could be due to a similar core focus on employment-related curriculum for both groups. Gaining financial stability could have contributed to positive improvements in other fatherhood domains. Implications for future research and practice are discussed herein.

El objetivo de este estudio fue analizar las diferencias en la crianza, el bienestar psicológico y los resultados económicos entre padres que recibían dos programas diferentes ofrecidos por el Centro de Apoyo a los Padres y las Familias (Fathers & Familiares Support Center) para padres desfavorecidos económicamente: (a) Formación de una Familia (Family Formation, FF), un programa de 6 semanas/240 horas centrado en la estabilidad/movilidad económica, la paternidad responsable y las relaciones saludables, con gestión de casos y servicios legales; (b) Estabilidad Económica (Economic Stability, ES), un programa de 4 semanas/80 horas centrado solamente en la estabilidad económica con poca gestión de casos y servicios legales. Se usó un ensayo controlado aleatorizado para comparar a los padres de FF (n=350) con los de ES (n=342). Se realizaron encuestas en la inscripción y a los 3 y a los 12 meses posteriores a la intervención. Se usaron modelos lineales y modelos mixtos lineales generalizados para evaluar los cambios en los resultados de los programas con el tiempo y entre los grupos de estudio. 482 padres respondieron a cada encuesta de seguimiento (251 FF, 231 ES). Casi todos (el 98 %) eran de color (el 93 % negros, el 5 % de otra raza o de raza mestiza) y tenían, en promedio, 34 años. Aproximadamente el 46 % asistió a más del 75 % de las sesiones de los programas (el 48 % de FF frente al 44 % de ES). Tanto el grupo de FF como el de ES tuvieron mejoras en la crianza, en el bienestar psicológico y en los resultados económicos después de los programas, pero los cambios en los resultados con el tiempo no variaron significativamente por programa. La falta de diferencia en los resultados entre los padres del grupo de FF y los del grupo de ES podría deberse a un enfoque principal similar en un currículo relacionado con el empleo para ambos grupos. La adquisición de estabilidad económica podría haber contribuido a mejoras positivas en otras áreas de la paternidad. Se comentan las consecuencias para la futura investigación y la práctica.

Periodoannulenes: A Generalized Annulene-within-an-Annulene Paradigm for Combined σ and π Ring Currents.

Periodoannulene molecules and ions CxIxq in planar geometry offer examples of systems with the potential for outer σ and inner π ring-current double aromaticity, given a sufficient overlap of tangential pσ-orbital manifolds on the large atoms of the outer cycle. Previous theoretical work indicated concentric diatropic currents in the dication C6I62+. Ab initio ipsocentric calculations support an account in terms of frontier-orbital selection rules for current contributions in C6I62+ (and radical C6I6+, implicated in recent experimental work on the oxidation of periodobenzene). A σ/π analogue of the annulene-within-an-annulene model is applied here to periodo systems based on cyclooctatetraene. Model species C8I8q with charges q = 0, +1, +2, +4, -2 and structures constrained to a planar D4h symmetry exhibit maps with all combinations of σ/π con- and counter-rotation, comprising global σ ring currents on the iodine perimeter and central π ring currents on the carbocycle. All can be rationalized by the separate application of the tropicity selection rules to the two subsystems, whether in singlet or triplet states.

Modelling aromatisation of (BN)nH2n azabora-annulenes.

Despite a long tradition of descriptions of borazine as an 'inorganic benzene', this molecule is a non-aromatic species according to the magnetic (ring-current) criterion. Borazine, borazocine, and the larger neutral (BN)nH2n azabora-annulene heterocycles in planar conformations, although π-isoelectronic with [2n]annulenes, support only localized induced currents in perpendicular magnetic fields. The π-current maps of these systems comprise superpositions of separate 'lone-pair' circulations on all nitrogen centres. For the systems with n > 4, planarity must be enforced by a constraint. Qualitative orbital analysis based on the ipsocentric approach to calculation of induced current density suggests that global induced currents could be produced through strategic changes to the π electron count. In ab initio calculations, azabora-annulenes with rings of size [8]- and larger were indeed found to support global diatropic ring currents in both anionic and cationic forms with (4N + 2) π electron counts. The planar conformation of the charged ring typically occupies a stationary point of higher order on the potential energy surface, rather than a minimum. However, the borazocine dianion, [B4N4H8]2-, occupies a planar minimum, supports a diatropic ring current of strength comparable to that in benzene, and is predicted to participate in sandwich compounds; it is therefore a good candidate for an aromatised azabora-annulene.

Design of annulene-within-an-annulene systems by the altanisation approach. A study of altan-[n]annulenes.

The altanisation strategy, devised to design molecules with large and paratropic perimeter circulations, is applied to the family of [n]annulenes to give, altan-[n]annulenes, i.e. [n,5]coronenes. Analytical expressions are obtained for the eigenvalues of the Hückel Hamiltonian for altan-[n]annulenes, and used in conjunction with selection rules derived from the ipsocentric approach to predict patterns of global ring current in these systems. Density-functional calculations performed on seven altan-[n]annulenes, three neutral and four charged, give current-density maps in essential agreement with the predictions obtained at the unperturbed Hückel level. All but one of the systems show patterns with the tropicities expected for isolated annulenes, in line with the altanisation concept. The apparent exception is altan-[11]annulene-, the only singlet system with a well defined open-shell character in the studied set. The key role of open-shell character can be accommodated by appropriate choice of the occupation numbers of the initial Hückel molecular orbitals, where the anion altan-[11]annulene- is considered as an [11]annulene inside the [22]annulene anion.

Molecular graphs and molecular conduction: the d-omni-conductors.

Ernzerhof's source-and-sink-potential (SSP) model for ballistic conduction in conjugated π systems predicts transmission of electrons through a two-wire device in terms of characteristic polynomials of the molecular graph and subgraphs based on the pattern of connections. We present here a complete classification of conduction properties of all molecular graphs within the SSP model. An omni-conductor/omni-insulator is a molecular graph that conducts/insulates at the Fermi level (zero of energy) for all connection patterns. In the new scheme, we define d-omni-conduction/insulation in terms of Fermi-level conduction/insulation for all devices with graph distance d between connections. This gives a natural generalisation to all graphs of the concept of near-omni-conduction/insulation previously defined for bipartite graphs only. Every molecular graph can be assigned to a nullity class and a compact code defining conduction behaviour; each graph has 0, 1, >1 zero eigenvalues (non-bonding molecular orbitals), and three letters drawn from {C, I, X} indicate conducting, insulating or mixed behaviour within the sets of devices with connection vertices at odd, even and zero distances d. Examples of graphs (in 28 cases chemical) are given for 35 of the 81 possible combinations of nullity and letter codes, and proofs of non-existence are given for 42 others, leaving only four cases open.

A Correlated Source-Sink-Potential Model Consistent with the Meir-Wingreen Formula.

We model a molecular device as a molecule attached to a set of leads treated at the tight-binding level, with the central molecule described to any desired level of electronic structure theory. Within this model, in the absence of electron-phonon interactions, the Landauer-Büttiker part of the Meir-Wingreen formula is shown to be sufficient to describe the transmission factor of the correlated device. The key to this demonstration is to ensure that the correlation self-energy has the same functional form as the exact correlation self-energy. This form implies that nonsymmetric contributions to the Meir-Wingreen formula vanish, and hence, conservation of current is achieved without the need for Green's Function self-consistency. An extension of the Source-Sink-Potential (SSP) approach gives a computational route to the calculation and interpretation of electron transmission in correlated systems. In this picture, current passes through internal molecular channels via resonance states with complex-valued energies. Each resonance state arises from one of the states in the Lehmann expansion of the one-electron Green's function, hole conduction derived from ionized states, and particle conduction from attached states. In the correlated device, the dependence of transmission on electron energy is determined by four structural polynomials, as it was in the tight-binding (Hückel) version of the SSP method. Hence, there are active and inert conduction channels (in the correlated case, linked to Dyson orbitals) governed by a set of selection rules that map smoothly onto the simplest picture.

Ring-Current Maps for Benzenoids: Comparisons, Contradictions, and a Versatile Combinatorial Model.

As a key diagnostic property of benzenoids and other polycyclic hydrocarbons, induced ring current has inspired diverse approaches for calculation, modeling, and interpretation. Grid-based methods include the ipsocentric ab initio calculation of current maps, and its surrogate, the pseudo-π model. Graph-based models include a family of conjugated-circuit (CC) models and the molecular-orbital Hückel-London (HL) model. To assess competing claims for physical relevance of derived current maps for benzenoids, a protocol for graph-reduction and comparison was devised. Graph reduction of pseudo-π grid maps highlights their overall similarity to HL maps, but also reveals systematic differences. These are ascribed to unavoidable pseudo-π proximity limitations for benzenoids with short nonbonded distances, and to poor continuity of pseudo-π current for classes of benzenoids with fixed bonds, where single-reference methods can be unreliable. Comparison between graph-based approaches shows that the published CC models all shadow HL maps reasonably well for most benzenoids (as judged by L1-, L2-, and L∞-error norms on scaled bond currents), though all exhibit physically implausible currents for systems with fixed bonds. These comparisons inspire a new combinatorial model (Model W) based on cycle decomposition of current, taking into account the two terms of lowest order that occur in the characteristic polynomial. This improves on all pure-CC models within their range of applicability, giving excellent adherence to HL maps for all Kekulean benzenoids, including those with fixed bonds (halving the rms discrepancy against scaled HL bond currents, from 11% in the best CC model, to 5% for the set of 18 360 Kekulean benzenoids on up to 10 hexagonal rings). Model W also has excellent performance for open-shell systems, where currents cannot be described at all by pure CC models (4% rms discrepancy against scaled HL bond currents for the 20112 non-Kekulean benzenoids on up to 10 hexagonal rings). Consideration of largest and next-to-largest matchings is a useful strategy for modeling and interpretation of currents in Kekulean and non-Kekulean benzenoids (nanographenes).

Solving Homelessness from a Complex Systems Perspective: Insights for Prevention Responses.

Homelessness represents an enduring public health threat facing communities across the developed world. Children, families, and marginalized adults face life course implications of housing insecurity, while communities struggle to address the extensive array of needs within heterogeneous homeless populations. Trends in homelessness remain stubbornly high despite policy initiatives to end homelessness. A complex systems perspective provides insights into the dynamics underlying coordinated responses to homelessness. A constant demand for housing assistance strains service delivery, while prevention efforts remain inconsistently implemented in most countries. Feedback processes challenge efficient service delivery. A system dynamics model tests assumptions of policy interventions for ending homelessness. Simulations suggest that prevention provides a leverage point within the system; small efficiencies in keeping people housed yield disproportionately large reductions in homelessness. A need exists for policies that ensure reliable delivery of coordinated prevention efforts. A complex systems approach identifies capacities and constraints for sustainably solving homelessness.

In search of Coulson's lost theorem.

In Hückel theory, the bond number is the sum of the orders of the π bonds incident on a given carbon center. From the work of Coulson and his school, it has been believed for over 70 years that the bond number has a maximum of 3 and that this bound is realized by exactly one conjugated framework, that of the trimethylenemethane radical. Search of published literature and archived correspondence failed to find any formal proof of these two statements. Here, we provide a new formula for bond number that leads to an easily checked proof of both. The bond number of graphene is 1.574 597… (90.9% of the mathematical limit), and this value appears to act as a separator for the classes of metallic and semiconducting single-walled nanotubes, as defined within Hückel theory.

Social Cohesion, Neighborhood Collective Efficacy, and Adolescent Subjective Well-being in Urban and Rural Taiwan.

This study investigates the association between neighborhood social cohesion, collective efficacy, and adolescent subjective well-being in a nationally representative sample of Taiwanese youth. The study represents a first to adapt and test a developmental ecological model within a Chinese cultural context. Data came from the Taiwan Youth Project, which assessed representative samples of seventh graders (n = 2,690) and ninth graders (n = 2,851) from both urban and rural counties. The analytic sample included 4,988 adolescents (M age = 14.4, SD = 1.14; 50% female) in Taiwan. A path analysis estimated the direct and indirect effects of social cohesion on adolescent well-being. The results suggest that neighbors can affect young people's well-being by reinforcing their perception of safety and enhancing their self-esteem. Comparisons between youth from urban and rural areas demonstrate a general similarity in the developmental processes, though the perception of safety is less of a concern in rural areas. Findings emphasize universal aspects of neighborhood collective efficacy and developmental-ecological models, as well as allude to culturally specific dimensions in a Chinese-based context.

Exposure to Community Violence and the Trajectory of Internalizing and Externalizing Symptoms in a Sample of Low-Income Urban Youth.

This study examined trajectories of psychopathology in a sample of low-income urban youth and tested exposure to community violence as a predictor of these trajectories. Self-report and parent-report survey measures of psychological problems and exposure to community violence were collected annually over 3 years from a sample of 364 fifth- to ninth-grade low-income urban youth (64% female; 95% youth of color). Linear growth models showed that youth experienced declines in both internalizing and externalizing symptoms across adolescence. Exposure to community violence was more strongly associated with externalizing symptoms than with internalizing symptoms but predicted declines in both types of symptoms. Results also indicated that youth reported more internalizing and externalizing symptoms than their parents reported for them. Exposure to community violence may explain unique trajectories of mental health problems among low-income urban youth. In addition, youth efforts to adopt a tough façade in the face of community violence could lead to higher rates of externalizing problems relative to internalizing problems, whereas desensitization processes may better explain reductions in both types of symptoms over time. Finally, youth report may be more valid than parent report in the context of urban poverty.

Tracking heavy water (D2O) incorporation for identifying and sorting active microbial cells.

Microbial communities are essential to the function of virtually all ecosystems and eukaryotes, including humans. However, it is still a major challenge to identify microbial cells active under natural conditions in complex systems. In this study, we developed a new method to identify and sort active microbes on the single-cell level in complex samples using stable isotope probing with heavy water (D2O) combined with Raman microspectroscopy. Incorporation of D2O-derived D into the biomass of autotrophic and heterotrophic bacteria and archaea could be unambiguously detected via C-D signature peaks in single-cell Raman spectra, and the obtained labeling pattern was confirmed by nanoscale-resolution secondary ion MS. In fast-growing Escherichia coli cells, label detection was already possible after 20 min. For functional analyses of microbial communities, the detection of D incorporation from D2O in individual microbial cells via Raman microspectroscopy can be directly combined with FISH for the identification of active microbes. Applying this approach to mouse cecal microbiota revealed that the host-compound foragers Akkermansia muciniphila and Bacteroides acidifaciens exhibited distinctive response patterns to amendments of mucin and sugars. By Raman-based cell sorting of active (deuterated) cells with optical tweezers and subsequent multiple displacement amplification and DNA sequencing, novel cecal microbes stimulated by mucin and/or glucosamine were identified, demonstrating the potential of the nondestructive D2O-Raman approach for targeted sorting of microbial cells with defined functional properties for single-cell genomics.

Housing decisions among homeless families involved in the child welfare system.

The present study embedded a qualitative sub-study within a randomized controlled trial of housing services for child welfare-involved families to examine housing decisions made in the face of homelessness and child protection. Participants included a representative sample of caregivers (n = 19) randomized to receive the Family Unification Program - a permanent housing intervention for inadequately housed families under investigation for child abuse or neglect - or child welfare services-as-usual. Qualitative interviews 12 months after randomization assessed housing decision-making processes involved in keeping families safe and stable. Results indicated a push-pull dynamic that constrained housing choices regardless of whether permanent housing was made available. Caregiver housing decisions were constrained by time limitations, affordability, and access to services, while child and family safety was perceived as less important. Findings emphasize the need for housing informed child welfare services to ensure the long-term safety of children in families experiencing homelessness.

Raman Deuterium Isotope Probing Reveals Microbial Metabolism at the Single-Cell Level.

We illustrate that single-cell Raman microspectroscopy, coupled with deuterium isotope probing (Raman-DIP), provides a culture-independent and nondestructive approach to probe metabolic pathways of carbon substrates at the single-cell level. We found a distinguishable C-D vibration band at 2070-2300 cm-1 in single-cell Raman spectra (SCRS) when Escherichia coli used deuterated glucose and Pseudomonas sp. used deuterated naphthalene as sole carbon sources. The intensity of the C-D band is proportional to the extent of deuteration in the carbon source, and as little as 5% deuteration can be distinguished by analysis of SCRS. It suggests that Raman-DIP could be used to semiquantitatively and sensitively indicate the metabolism of deuterated carbon source in microbes. A lower lipid conversion rate of deuterated naphthalene compared to that of deuterated glucose was observed, presumably owing to different anabolic pathways and membrane alteration. Apart from the C-D band shift from C-H, SCRS also reveal several isotopic shifts of the phenylalanine band, of which the positions correlate well with a computational model. A reduction in phenylalanine deuteration in Pseudomonas sp. compared to that in E. coli is due to the dilution effect of different pathways of phenylalanine biosynthesis in Pseudomonas sp. Collectively, we demonstrate that Raman-DIP can not only indicate metabolic activity using deuterated carbon sources but also reveal different metabolic pathways by analyzing SCRS. By harnessing such low-cost and versatile deuterated substrates, Raman-DIP has the potential to probe a wide range of metabolic pathways and functions at the single-cell level.

From C(58) to C(62) and back: Stability, structural similarity, and ring current.

An increasing number of observations show that non-classical isomers may play an important role in the formation of fullerenes and their exo- and endo-derivatives. A quantum-mechanical study of all classical isomers of C58 , C60 , and C62 , and all non-classical isomers with at most one square or heptagonal face, was carried out. Calculations at the B3LYP/6-31G* level show that the favored isomers of C58 , C60 , and C62 have closely related structures and suggest plausible inter-conversion and growth pathways among low-energy isomers. Similarity of the favored structures is reinforced by comparison of calculated ring currents induced on faces of these polyhedral cages by radial external magnetic fields, implying patterns of magnetic response similar to those of the stable, isolated-pentagon C60 molecule. © 2016 Wiley Periodicals, Inc.

Bespoke Diblock Copolymer Nanoparticles Enable the Production of Relatively Stable Oil-in-Water Pickering Nanoemulsions.

Sterically stabilized diblock copolymer nanoparticles with an intensity-average diameter of 25 nm are prepared in the form of a concentrated aqueous dispersion using polymerization-induced self-assembly (PISA). The addition of n-dodecane followed by high-shear homogenization produces n-dodecane-in-water Pickering macroemulsions of 22-46 µm diameter. If the nanoparticles are present in sufficient excess, then subsequent processing using a high-pressure microfluidizer leads to the formation of Pickering nanoemulsions with a mean oil droplet diameter below 200 nm. The size of these Pickering nanoemulsions can be tuned by systematically varying the nanoparticle concentration, applied pressure, number of passes, and oil volume fraction. High-internal-phase emulsions can also be achieved by increasing the n-dodecane volume fraction up to 0.80. TEM studies of (dried) n-dodecane droplets confirm the presence of intact nanoparticles and suggest a relatively high surface coverage, which is consistent with model packing calculations based on radius ratios. Such Pickering nanoemulsions proved to be surprisingly stable with respect to Ostwald ripening, with no significant change in the mean DLS droplet diameter after storage for approximately 4 months at 20 °C.

Near omni-conductors and insulators: Alternant hydrocarbons in the SSP model of ballistic conduction.

Within the source-and-sink-potential model, a complete characterisation is obtained for the conduction behaviour of alternant π-conjugated hydrocarbons (conjugated hydrocarbons without odd cycles). In this model, an omni-conductor has a molecular graph that conducts at the Fermi level irrespective of the choice of connection vertices. Likewise, an omni-insulator is a molecular graph that fails to conduct for any choice of connections. We give a comprehensive classification of possible combinations of omni-conducting and omni-insulating behaviour for molecular graphs, ranked by nullity (number of non-bonding orbitals). Alternant hydrocarbons are those that have bipartite molecular graphs; they cannot be full omni-conductors or full omni-insulators but may conduct or insulate within well-defined subsets of vertices (unsaturated carbon centres). This leads to the definition of "near omni-conductors" and "near omni-insulators." Of 81 conceivable classes of conduction behaviour for alternants, only 14 are realisable. Of these, nine are realised by more than one chemical graph. For example, conduction of all Kekulean benzenoids (nanographenes) is described by just two classes. In particular, the catafused benzenoids (benzenoids in which no carbon atom belongs to three hexagons) conduct when connected to leads via one starred and one unstarred atom, and otherwise insulate, corresponding to conduction type CII in the near-omni classification scheme.