Bithiophenesulfonamide Building Block for π-Conjugated Donor-Acceptor Semiconductors.

We report here π-conjugated small molecules and polymers based on the new π-acceptor building block, bithiophenesulfonamide (BTSA). Molecular orbital computations and optical, electrochemical, and crystal structure analyses illuminate the architecture and electronic structure of the BTSA unit versus other acceptor building blocks. Field-effect transistors and photovoltaic cells demonstrate that BTSA is a promising unit for the construction of π-conjugated semiconducting materials.

Metal-free tetrathienoacene sensitizers for high-performance dye-sensitized solar cells.

A new series of metal-free organic chromophores (TPA-TTAR-A (1), TPA-T-TTAR-A (2), TPA-TTAR-T-A (3), and TPA-T-TTAR-T-A (4)) are synthesized for application in dye-sensitized solar cells (DSSC) based on a donor-π-bridge-acceptor (D-π-A) design. Here a simple triphenylamine (TPA) moiety serves as the electron donor, a cyanoacrylic acid as the electron acceptor and anchoring group, and a novel tetrathienoacene (TTA) as the π-bridge unit. Because of the extensively conjugated TTA π-bridge, these dyes exhibit high extinction coefficients (4.5-5.2 × 10(4) M(-1) cm(-1)). By strategically inserting a thiophene spacer on the donor or acceptor side of the molecules, the electronic structures of these TTA-based dyes can be readily tuned. Furthermore, addition of a thiophene spacer has a significant influence on the dye orientation and self-assembly modality on TiO2 surfaces. The insertion of a thiophene between the π-bridge and the cyanoacrylic acid anchoring group in TPA-TTAR-T-A (dye 3) promotes more vertical dye orientation and denser packing on TiO2 (molecular footprint = 79 Å(2)), thus enabling optimal dye loading. Using dye 3, a DSSC power conversion efficiency (PCE) of 10.1% with Voc = 0.833 V, Jsc = 16.5 mA/cm(2), and FF = 70.0% is achieved, among the highest reported to date for metal-free organic DSSC sensitizers using an I(-)/I3(-) redox shuttle. Photophysical measurements on dye-grafted TiO2 films reveal that the additional thiophene unit in dye 3 enhances the electron injection efficiency, in agreement with the high quantum efficiency.

Electron pairing in designer materials: a novel strategy for a negative effective Hubbard U.

We propose a set of design rules with a model Hamiltonian that allows electrons to form attracting pairs through the exploitation of a new combination of resonant band alignment and Coulombic repulsion. The pair bands and single particle bands in various lattices are calculated and compared in energy, and regions of net attraction are identified. This work provides guidelines for the construction of molecular systems, nanocrystals, and nanoparticle arrays with the potential for superconductivity.

Substantial photovoltaic response and morphology tuning in benzo[1,2-b:6,5-b']dithiophene (bBDT) molecular donors.

The influence of solubilizing substituents on the photovoltaic performance and thin-film blend morphology of new benzo[1,2-b:6,5-b']dithiophene (bBDT) based small molecule donor semiconductors is investigated. Solar cells based on bBDT(TDPP)2-PC71BM with two different types of side chains exhibit high power conversion efficiencies, up to 5.53%.

Bithiopheneimide-dithienosilole/dithienogermole copolymers for efficient solar cells: information from structure-property-device performance correlations and comparison to thieno[3,4-c]pyrrole-4,6-dione analogues.

Rational creation of polymeric semiconductors from novel building blocks is critical to polymer solar cell (PSC) development. We report a new series of bithiopheneimide-based donor-acceptor copolymers for bulk-heterojunction (BHJ) PSCs. The bithiopheneimide electron-deficiency compresses polymer bandgaps and lowers the HOMOs--essential to maximize power conversion efficiency (PCE). While the dithiophene bridge progression R(2)Si→R(2)Ge minimally impacts bandgaps, it substantially alters the HOMO energies. Furthermore, imide N-substituent variation has negligible impact on polymer opto-electrical properties, but greatly affects solubility and microstructure. Grazing incidence wide-angle X-ray scattering (GIWAXS) indicates that branched N-alkyl substituents increased polymer π-π spacings vs linear N-alkyl substituents, and the dithienosilole-based PBTISi series exhibits more ordered packing than the dithienogermole-based PBTIGe analogues. Further insights into structure-property-device performance correlations are provided by a thieno[3,4-c]pyrrole-4,6-dione (TPD)-dithienosilole copolymer PTPDSi. DFT computation and optical spectroscopy show that the TPD-based polymers achieve greater subunit-subunit coplanarity via intramolecular (thienyl)S···O(carbonyl) interactions, and GIWAXS indicates that PBTISi-C8 has lower lamellar ordering, but closer π-π spacing than does the TPD-based analogue. Inverted BHJ solar cells using bithiopheneimide-based polymer as donor and PC(71)BM as acceptor exhibit promising device performance with PCEs up to 6.41% and V(oc) > 0.80 V. In analogous cells, the TPD analogue exhibits 0.08 V higher V(oc) with an enhanced PCE of 6.83%, mainly attributable to the lower-lying HOMO induced by the higher imide group density. These results demonstrate the potential of BTI-based polymers for high-performance solar cells, and provide generalizable insights into structure-property relationships in TPD, BTI, and related polymer semiconductors.

The movements of limb segments and joints during locomotion in African and Asian elephants.

As the largest extant terrestrial animals, elephants do not trot or gallop but can move smoothly to faster speeds without markedly changing their kinematics, yet with a shift from vaulting to bouncing kinetics. To understand this unusual mechanism, we quantified the forelimb and hindlimb motions of eight Asian elephants (Elephas maximus) and seven African elephants (Loxodonta africana). We used 240 Hz motion analysis (tracking 10 joint markers) to measure the flexion/extension angles and angular velocities of the limb segments and joints for 288 strides across an eightfold range of speeds (0.6-4.9 m s(-1)) and a sevenfold range of body mass (521-3684 kg). We show that the columnar limb orientation that elephants supposedly exemplify is an oversimplification--few segments or joints are extremely vertical during weight support (especially at faster speeds), and joint flexion during the swing phase is considerable. The 'inflexible' ankle is shown to have potentially spring-like motion, unlike the highly flexible wrist, which ironically is more static during support. Elephants use approximately 31-77% of their maximal joint ranges of motion during rapid locomotion, with this fraction increasing distally in the limbs, a trend observed in some other running animals. All angular velocities decrease with increasing size, whereas smaller elephant limbs are not markedly more flexed than adults. We find no major quantitative differences between African and Asian elephant locomotion but show that elephant limb motions are more similar to those of smaller animals, including humans and horses, than commonly recognized. Such similarities have been obscured by the reliance on the term ;columnar' to differentiate elephant limb posture from that of other animals. Our database will be helpful for identifying elephants with unusual limb movements, facilitating early recognition of musculoskeletal pathology.

Subcapsular hepatic hematoma with right hepatic vein thrombosis: a complication of shock wave lithotripsy.

Extracorporeal shock wave lithotripsy (ESWL) is a well-established, safe and effective therapeutic modality for surgical treatment of urolithiasis. Hematoma is a rare complication of ESWL and, when it occurs, typically involves the kidney. We report the case of a 71-year-old woman who developed severe, persistent abdominal pain after ESWL for a 9-mm stone at the ureteropelvic junction. Post-treatment CT scan demonstrated a 13 x 6-cm subcapsular hepatic hematoma. A follow-up CT scan showed expansion of the hematoma and development of hepatic vein thrombosis. This finding, along with persistent abdominal pain and rising liver transaminases, led to surgical intervention. The patient's symptoms resolved and liver function returned to baseline following liver decompression.

Adolescent psychopathy features: 6-year temporal stability and the prediction of externalizing symptoms during the transition to adulthood.

This study investigated the 6-year stability and predictive validity of adolescent psychopathy features during the transition to young adulthood. It represents one of the longest outcome studies of youth psychopathy to date, and therefore addresses a primary criticism of the research area (i.e., lack of demonstrated associations between child and adult psychopathy features). Recruited participants were 475 males enrolled in the Minnesota Twin and Family Study who had completed a research-based measure of psychopathy features consisting of separate emotional detachment (or affective) and antisocial tendencies (or behavioral) subscales. These psychopathy features and various externalizing symptoms (i.e., conduct problems, impulsivity, and substance use disorder) were assessed through rating scales and structured diagnostic interview at an intake assessment (ages 16-18) and 6-year follow-up. Consistent with prediction, adolescent psychopathy features displayed moderate stability across the transition from adolescence to adulthood [intraclass correlation coefficients (ICCs) = 0.40-0.41]. The antisocial tendencies subscale was uniquely related to most externalizing symptoms both in adolescence and in adulthood, whereas the emotional detachment subscale showed appropriate discriminant validity in its lack of association with externalizing symptoms. These findings suggest that psychopathy features are relatively stable from adolescence to adulthood and provide possible insights into the development and maintenance of externalizing difficulties during the adult transition.

Associations of phenylthiocarbamide tasting to alcohol problems and family history of alcoholism differ by gender.

Past research associating phenylthiocarbamide/propylthiouracil (PTC/PROP) taste status with alcoholism has produced equivocal results. Some have found higher proportions of nontasters among those with a family history of alcoholism than controls, whereas others have not. The purpose of this study was to investigate the relationship between PTC taste status, alcohol problems, and family history of alcoholism. A total of 244 undergraduate students participated in this study, with a gender distribution of 75% female and 25% male. We found support for our hypothesis that male supertasters would report fewer problems with alcohol and a less significant family history of alcoholism. Interestingly, we also found that female supertasters had a greater family history of alcoholism and more current problems associated with alcohol use. Implications for the genetic link between PTC taste status and alcoholism are discussed.

Trait affectivity and non-referred adolescent conduct problems.

This study examined for profiles of positive trait affectivity (PA) and negative trait affectivity (NA) associated with adolescent conduct problems. Prior trait affectivity research has been relatively biased toward the assessment of adults and internalizing symptomatology. Consistent with recent developmental modeling of antisocial behavior, this study proposed that conduct problems are uniquely associated with 2 PA-NA profiles (i.e., high PA-high NA and low PA-low NA). A non-referred sample of 109 adolescents ages 12 to 19 was recruited to assess the independent relations between rating scale measures of the PA-NA dimensions and conduct problems, controlling for related internalizing (anxiety and depression) and externalizing (hyperactivity-impulsivity) symptomatology. The results generally confirmed the proposed interaction between the PA-NA dimensions in the prediction of adolescent conduct problems.

The relation between salivary cortisol, callous-unemotional traits, and conduct problems in an adolescent non-referred sample.

BACKGROUND: Previous research has suggested that adult psychopathic behavior and child callous-unemotional (CU) traits are uniquely related to low emotional reactivity. Salivary cortisol is a promising biological measure of emotional reactivity that has been relatively overlooked in research on CU traits and antisocial behavior. The current study examined for gender differences in the relation between resting salivary cortisol levels and CU traits in a non-referred adolescent sample. Salivary testosterone levels were assessed to provide discriminant validity for cortisol analyses and were not expected to bear a relation to CU traits. METHOD: An extreme groups strategy was used to recruit 108 adolescents (53 male, 55 female) from a larger screening sample who exhibited various combinations of low and high scores on parent-report measures of CU traits and conduct problems. Resting saliva samples were assayed for cortisol and testosterone levels using a radioimmunoassay procedure. RESULTS: Consistent with prediction, male participants exhibiting elevated CU traits were uniquely characterized by low cortisol levels relative to male comparison groups (p<.05). Testosterone levels did not differentiate groups and no hormone effects were found for female participants. CONCLUSIONS: The current findings build upon recent research in suggesting that low cortisol may be a biological marker for male CU traits.

Clinical applications of the interpersonal-psychological theory of attempted and completed suicide.

This article reviews the interpersonal-psychological theory of attempted and completed suicide and describes its applications in suicide risk assessment, crisis intervention, and skills-based psychotherapies. Three components are necessary, but not sufficient, for an individual to die by suicide: (1) the acquired capability to enact lethal self-injury, (2) a sense that one is a burden on others, and (3) the sense that one does not belong to a valued social group. We suggest that therapeutic interventions should focus on ascertaining the presence of these components and work to amend the cognitive distortions, negative interpersonal response styles, and ineffective coping behaviors that serve to maintain suicidal urges.