Structure Dependence of Kinetic and Thermodynamic Parameters in Singlet Fission Processes

Singlet fission—whereby one absorbed photon generates two coupled triplet excitons—is a key process for increasing the efficiency of optoelectronic devices by overcoming the Shockley–Queisser limit. A crucial parameter is the rate of dissociation of the coupled triplets, as this limits the number of free triplets subsequently available for harvesting and ultimately the overall efficiency of the device. Here we present an analysis of the thermodynamic and kinetic parameters for this process in parallel and herringbone dimers measured by electron paramagnetic resonance spectroscopy in coevaporated films of pentacene in p-terphenyl. The rate of dissociation is higher for parallel dimers than for their herringbone counterparts, as is the rate of recombination to the ground state. DFT calculations, which provide the magnitude of the electronic coupling as well as the distribution of molecular orbitals for each geometry, suggest that weaker triplet coupling in the parallel dimer is the driving force for faster dissociation. Conversely, localization of the molecular orbitals and a stronger triplet–triplet interaction result in slower dissociation and recombination. The identification and understanding of how the intermolecular geometry promotes efficient triplet dissociation provide the basis for control of triplet coupling and thereby the optimization of one important parameter of device performance

Maternal iron deficiency perturbs embryonic cardiovascular development in mice.

Congenital heart disease (CHD) is the most common class of human birth defects, with a prevalence of 0.9% of births. However, two-thirds of cases have an unknown cause, and many of these are thought to be caused by in utero exposure to environmental teratogens. Here we identify a potential teratogen causing CHD in mice: maternal iron deficiency (ID). We show that maternal ID in mice causes severe cardiovascular defects in the offspring. These defects likely arise from increased retinoic acid signalling in ID embryos. The defects can be prevented by iron administration in early pregnancy. It has also been proposed that teratogen exposure may potentiate the effects of genetic predisposition to CHD through gene-environment interaction. Here we show that maternal ID increases the severity of heart and craniofacial defects in a mouse model of Down syndrome. It will be important to understand if the effects of maternal ID seen here in mice may have clinical implications for women

Identifying structure-absorption relationships and predicting absorption strength of non-fullerene acceptors for organic photovoltaics

Non-fullerene acceptors (NFAs) are excellent light harvesters, yet the origin of their high optical extinction is not well understood. In this work, we investigate the absorption strength of NFAs by building a database of time-dependent density functional theory (TDDFT) calculations of ∼500 π-conjugated molecules. The calculations are first validated by comparison with experimental measurements in solution and solid state using common fullerene and non-fullerene acceptors. We find that the molar extinction coefficient (εd,max) shows reasonable agreement between calculation in vacuum and experiment for molecules in solution, highlighting the effectiveness of TDDFT for predicting optical properties of organic π-conjugated molecules. We then perform a statistical analysis based on molecular descriptors to identify which features are important in defining the absorption strength. This allows us to identify structural features that are correlated with high absorption strength in NFAs and could be used to guide molecular design: highly absorbing NFAs should possess a planar, linear, and fully conjugated molecular backbone with highly polarisable heteroatoms. We then exploit a random decision forest algorithm to draw predictions for εd,max using a computational framework based on extended tight-binding Hamiltonians, which shows reasonable predicting accuracy with lower computational cost than TDDFT. This work provides a general understanding of the relationship between molecular structure and absorption strength in π-conjugated organic molecules, including NFAs, while introducing predictive machine-learning models of low computational cost

Starting Day Care in Espoo from the Viewpoint of Chinese Parents

The thesis is a small-scale evaluative research. The day care start folder, which provided practical and detailed information about starting Finnish day care to support multicultural parents in Otaniemi day-care centre and Servin-Maija day-care centre, was assessed among nine Chinese parents of children in five municipal and outsourced day-care centres in the City of Espoo. The purposes of the current research were to find out how Chinese parents perceive starting day care in the City of Espoo and their difficulties and suggestions concerning starting day care in the City of Espoo; to evaluate how the day care start folder is experienced as a working method in opinion of Chinese parents living in the City of Espoo; and to further improve the day care start folder as a working method for multicultural families and personnel in Otaniemi day-care centre and possibly for other day-care centres in the similar situation. Two types of interview, namely semi-structured individual interview and focus group interview, were utilised as the primary qualitative data-collecting methods in the current research. In addition, questionnaire as an assistant quantitative data-collecting method was employed as well to ensure verification of the consistency of the data, and supplement the abundance of the narrative data collected from interviews. The qualitative data gathered from the six interviews was coded, categorised and analysed in accordance with the method of content analysis. The results showed that the participating Chinese parents basically concerned about the information on starting day care; their child’s language learning; their communication and cooperation with day-care staff; cultures, religions and festivals; playing, learning and friends; child protection and legislation and so forth. Furthermore, these Chinese parents also put forward some important problems and suggestions on Finnish day care, such as problems caused by cultural differences, different opinions on learning by playing and Finnish as a second language-teaching, difficulties to obtain enough English information about Finnish day care, and the lack of mediums for foreign families to receive help concerning Finnish day care. In addition, these Chinese parents perceived the day care start folder as useful and adequate. The results based on the questionnaires supported and verified the results generated from the qualitative data analysis

A Requirement for Zic2 in the Regulation of Nodal Expression Underlies the Establishment of Left-Sided Identity

ZIC2 mutation is known to cause holoprosencephaly (HPE). A subset of ZIC2 HPE probands harbour cardiovascular and visceral anomalies suggestive of laterality defects. 3D-imaging of novel mouse Zic2 mutants uncovers, in addition to HPE, laterality defects in lungs, heart, vasculature and viscera. A strong bias towards right isomerism indicates a failure to establish left identity in the lateral plate mesoderm (LPM), a phenotype that cannot be explained simply by the defective ciliogenesis previously noted in Zic2 mutants. Gene expression analysis showed that the left-determining NODAL-dependent signalling cascade fails to be activated in the LPM, and that the expression of Nodal at the node, which normally triggers this event, is itself defective in these embryos. Analysis of ChiP-seq data, in vitro transcriptional assays and mutagenesis reveals a requirement for a low-affinity ZIC2 binding site for the activation of the Nodal enhancer HBE, which is normally active in node precursor cells. These data show that ZIC2 is required for correct Nodal expression at the node and suggest a model in which ZIC2 acts at different levels to establish LR asymmetry, promoting both the production of the signal that induces left side identity and the morphogenesis of the cilia that bias its distribution

Mice carrying a hypomorphic Evi1 allele are embryonic viable but exhibit severe congenital heart defects

The ecotropic viral integration site 1 (Evi1) oncogenic transcription factor is one of a number of alternative transcripts encoded by the Mds1 and Evi1 complex locus (Mecom). Overexpression of Evi1 has been observed in a number of myeloid disorders and is associated with poor patient survival. It is also amplified and/or overexpressed in many epithelial cancers including nasopharyngeal carcinoma, ovarian carcinoma, ependymomas, and lung and colorectal cancers. Two murine knockout models have also demonstrated Evi1's critical role in the maintenance of hematopoietic stem cell renewal with its absence resulting in the death of mutant embryos due to hematopoietic failure. Here we characterize a novel mouse model (designated Evi1(fl3)) in which Evi1 exon 3, which carries the ATG start, is flanked by loxP sites. Unexpectedly, we found that germline deletion of exon3 produces a hypomorphic allele due to the use of an alternative ATG start site located in exon 4, resulting in a minor Evi1 N-terminal truncation and a block in expression of the Mds1-Evi1 fusion transcript. Evi1(deltaex3/deltaex3) mutant embryos showed only a mild non-lethal hematopoietic phenotype and bone marrow failure was only observed in adult Vav-iCre/+, Evi1(fl3/fl3) mice in which exon 3 was specifically deleted in the hematopoietic system. Evi1(deltaex3/deltaex3) knockout pups are born in normal numbers but die during the perinatal period from congenital heart defects. Database searches identified 143 genes with similar mutant heart phenotypes as those observed in Evi1(deltaex3/deltaex3) mutant pups. Interestingly, 42 of these congenital heart defect genes contain known Evi1-binding sites, and expression of 18 of these genes are also effected by Evi1 siRNA knockdown. These results show a potential functional involvement of Evi1 target genes in heart development and indicate that Evi1 is part of a transcriptional program that regulates cardiac development in addition to the development of blood

Impact of day of a week on traffic flow in Kielce city center

Wiele osób codzienne przemieszcza się z miejsca zamieszkania do pracy, szkoły, sklepów, itp., często pokonując dość duże odległości. Ceniąc komfort i wygodę niektórzy decydują się na poruszanie własnym autem. Wzrastająca liczba samochodów jest szczególnie widoczna w miastach. W czasie tak zwanych godzin szczytu na ulicach miast pojawia się duża liczba samochodów, wzrasta natężenie ruchu i powstają miejsca, gdzie tworzą się korki. Kierow-ca musi liczyć się wówczas, że spadnie prędkość jazdy i czas przejazdu znacznie się wydłuży. Celem artykułu było zbadanie warunków przejazdu w określonych godzinach dla pięciu dni roboczych głównymi ulicami centrum Kielc. W przeprowadzonym badaniu zidentyfikowano punkty krytyczne, czyli ulice i skrzyżowania, gdzie zanotowano serie spadków i wzrostów prędkości, mające znaczny wpływ na płynność jazdy.Many people pass through their typical daily trips to work, school, shops, ect., overcoming a large distances. Valuing comfort and convenience, some people decide to move their own car. The increasing number of cars is particularly evident in the city center. Driving through the city during rush hour is really complicated and wasting commuters time. The aim of the paper was to investigate conditions of the travel through the main streets of the city center in Kielce at a specific time for five days. We identified critical points, which have significant impact on traffic flow. In this area vehicle recorded series of decreases and increases in speed

Analysis of suburban cycles worked out for Kielce public transport vehicles

W artykule omówiono budowę cykli ze względu na zapis funkcji prędkości w czasie. Przedstawiono cztery kieleckie cykle podmiejskie, mające posłużyć do dalszych badań symulacyjnych nad doborem najlepszego zasobnika energii dla autobusu hybrydowego, poruszającego się po kieleckich liniach podmiejskich. Opisano procedurę gromadzenia danych, dzięki którym zbudowano cykle zastępcze wielosegmentowe mieszane oraz przeprowadzono analizę porównawczą tych cykli. Wskazano cechy podobne oraz różnice występujące między czterema cyklami.The article describes the construction of cycles due to the data collected on the vehicles as some functions of the time. The contribution presents four suburban cycles determined for Kielce public transport buses. The cycles are to be used for further simulation studies to choose the best energy storage system for hybrid buses. The procedure of the data collection and evaluation, used to build multisegment suburban cycles has been described. The comparative analysis of all cycles has been presented. Some characteristics comparing all cycles and their differences have been shown

Analysis of the traffic flow on the entrance roads to Kielce

Z uwagi na utrzymujący się wzrost gospodarczy w Polsce, coraz więcej rodzin posiada nie jeden, a kilka samochodów. Co więcej, te samochody nie są prawidłowo wykorzystywane, bowiem podróżuje nimi nie pięć lecz często jedna osoba. Powoduje to wzrost liczby pojazdów na polskich drogach, szczególnie dotkliwie odczywany w miastach. Codzienne podróżowanie do pracy, jak i powroty do domu zajmują dużo czasu. Kierujący pojazdami znając trasę i punkt docelowy są w stanie unikać zatorów drogowych, poprzez wybór tras alternatywnych. W artykule wykonano charakterystykę pięciu głównych tras dojazdowych łączących stolicę świętokrzyskiego w kierunku takich miast jak Warszawa, Łódź, Kraków, Tarnów i Opatów. Przeprowadzono analizę wpływu pory dnia na średnią prędkość jazdy i czas podróży na drogach dojazdowych do centrum Kielc. Płynność ruchu określana między innymi wartością średniej prędkości na poszczególnych odcinkach, zależą m.in. od rodzaju drogi i pory dnia. „Najwolniejszymi” drogami dojazdowymi do Kielc okazały się kierunki: Kielce – Warszawa i Kielce – Łódź.Following economic growth in Poland, more and more families have not one, but several cars. What's more, the car is used not by five but by one person. So that we have an increase in the number of cars on Polish roads. Everyday plenty of people travel to the work and return homes and it takes a lot of time. Some people who travel the same road everyday know how to avoid traffic jams, by choosing alternative routes. The paper describes the impact of the time of the day on the average speed and the journey time of five main entrance roads to the Kielce from Warszawa, Łódź, Kraków, Tarnów and Opatów. We observed that the travel time and average speed depend on the time of the day, the number of crossroads with traffic lights and traffic flow. Kielce - Warszawa and Kielce – Łódź turned out to be the worst roads