Screening procedure for structurally and electronically matched contact layers for high-performance solar cells: hybrid perovskites

The rapid progress in performance of solar cells based on hybrid halide perovskites means that devices based on these materials have reached a stage where research interest can now focus on development of robust technology. One of the key questions relating to these (and indeed any) devices is their lifetime and stability which in turn is often influenced by the quality of interfaces and junctions within the device. In this study we present a methodology which allows screening for mechanically stable, electronically suitable interface combinations – applying the technique to screen 175 common semiconductors for viability as electron and hole extracting contacts for CH3NH3PbI3. The screening method can be applied to any semiconductor junction problem and relies on easily obtained experimental or theoretical information – electron affinity, ionisation potential, lattice parameters and crystal structure. From the screening we rank the candidates according to a figure of merit, which accounts for band alignment and chemical/mechanical stability of the interface. Our screening predicts stable interfaces with commonly applied electron extraction layers such as TiO2 and ZnO as well giving insight into the optimal polymorphs, surfaces and morphologies for achieving good quality contacts. Finally we also predict potentially effective new hole and electron extraction layers, namely Cu2O, FeO, SiC, GaN, and ZnTe

Approximation Algorithms for Connected Maximum Cut and Related Problems

An instance of the Connected Maximum Cut problem consists of an undirected graph G = (V, E) and the goal is to find a subset of vertices S $\subseteq$ V that maximizes the number of edges in the cut \delta(S) such that the induced graph G[S] is connected. We present the first non-trivial \Omega(1/log n) approximation algorithm for the connected maximum cut problem in general graphs using novel techniques. We then extend our algorithm to an edge weighted case and obtain a poly-logarithmic approximation algorithm. Interestingly, in stark contrast to the classical max-cut problem, we show that the connected maximum cut problem remains NP-hard even on unweighted, planar graphs. On the positive side, we obtain a polynomial time approximation scheme for the connected maximum cut problem on planar graphs and more generally on graphs with bounded genus.Comment: 17 pages, Conference version to appear in ESA 201

Aspectos morfométricos do tubo digestório de pacu (Piaractus mesopotamicus) submetidos à privação alimentar.

Resumo 658-2. 24º Reunião Anual da FeSBE

Influência das práticas de manejo e do exercício físico moderado sobre o metabolismo de matrinxã, Brycon amazonicus.

Matrinxãs (Brycon amazonicus; 25g; 10 cm) provenientes da Piscicultura Águas Claras (Mococa, SP) foram divididos em dois grupos: exercitado (natação forçada na velocidade de 2,0 comprimentos corporais segundo-1; EX) e sedentário (sem exercício; SD), mantidos no Laboratório de Zoofisiologia e Bioquímica Comparativa, UFSCar (São Carlos, SP) em aquários com 500 L de água, aeração e fluxo contínuos, 25 ºC, fotoperíodo 12/12 h e ração comercial

Detection of the hydroperoxyl radical HO2 toward \rho Oph A: Additional constraints on the water chemical network

Context: Hydrogen peroxide (HOOH) was recently detected toward \rho Oph A. Subsequent astrochemical modeling that included reactions in the gas phase and on the surface of dust grains was able to explain the observed abundance, and highlighted the importance of grain chemistry in the formation of HOOH as an intermediate product in water formation. This study also predicted that the hydroperoxyl radical HO2, the precursor of HOOH, should be detectable. Aims: We aim at detecting the hydroperoxyl radical HO2 in \rho Oph A. Methods: We used the IRAM 30m and the APEX telescopes to target the brightest HO2 lines at about 130 and 260 GHz. Results: We detect five lines of HO2 (comprising seven individual molecular transitions). The fractional abundance of HO2 is found to be about 1e-10, a value similar to the abundance of HOOH. This observational result is consistent with the prediction of the above mentioned astrochemical model, and thereby validates our current understanding of the water formation on dust grains. Conclusions: This detection, anticipated by a sophisticated gas-grain chemical model, demonstrates that models of grain chemistry have improved tremendously and that grain surface reactions now form a crucial part of the overall astrochemical network.Comment: 5 pages, 4 figures, accepted for publication as a Letter to the Editor in Astronomy and Astrophysic

Reproductive parameters of dairy goats submitted to estrus synchronization with prostaglandin F2alfa associated or not to hCG at estrous onset.

Abstract: The objective of this study was to evaluate the efficiency of two doses of PGF associated or not to hCG on the associated reproductive parameters in dairy goats. A total of 29 goats received two doses of 30 ug d-cloprostenol latero-vulvar at a 10 day intervals (Day 1 and Day 10). The does were allocated according to body weight and body condition score into two treatments, to receive hCG (250IU) or saline at estrus onset. After the second dose of PGF, estrus was monitored and ultrasound exams were performed twice daily. All does were inseminated 16h after estrus onset. Blood collection was performed every day for progesterone assay. The use of hCG at estrus onset did not affect any studied parameter and therefore the data were pooled. Estrous response rate was similar (P>0.05) after the first (75.9%, 22/29) and the second dose of PGF (79.3%, 23/29). The interval between the administration of PGF and estrus onset was greater (P0.05) between both experimental groups were detected in the following parameters, averaging: the interval from the second dose administration to the ovulation (86.6±11.4h), interval from estrus to ovulation (39.9±12.3 h), diameter of largest follicle (7.2±1.4) and number of ovulations (1.8±0.6). At Day 1, 52.4% (11/21) of does presented progesterone concentrations 1ng/mL. The results of the present study indicate that estrus can be efficiently synchronized in dairy goats with the use of two doses of PGF at a 10 day interval. Further research should be done evaluating hCG use in different doses or moments of administration. [Parâmetros ovarianos de cabras leiteira submetidas a sincronização do estro com protaglandina F2 alfa associada ou não ao hCG no início do estro]. Resumo: O objetivo deste estudo foi avaliar a eficiência do uso de duas doses de PGF associadas ou não à administração de hCG no início do estro sobre os parâmetros reprodutivos de cabras leiteiras. Um total de 29 cabras receberam duas doses de 30 ?g d-cloprostenol pela via latero-vulvar com 10 dias de intervalo (Dia 1 e Dia 10). As cabras foram alocadas para receberem o hCG (250 IU) ou salina i.m. no momento em que o estro foi detectado. Depois da realização da segunda dose de PGF, o estro foi monitorado e exames ultrassonográficos foram realizados duas vezes ao dia. Todas as fêmeas foram inseminadas 16 h após o inicio do estro. Amostras de sangue foram coletadas diariamente para determinação das concentrações plasmáticas de progesterona. O uso do hCG no momento do início do estro não afetou os parâmetros estudados e, portanto, os dados serão apresentados agrupados. A taxa de manifestação de estro foi similar (P > 0,05) na primeira (75,9% - 22/29) ou na segunda dose de PGF (79,3% - 23/29). O intervalo entre a administração de PGF e o início do estro foi maior (P 0,05) entre os grupos experimentais quanto aos parâmetros reprodutivos: intervalo entre a aplicação da segunda dose e a ovulação (86,6±11,4h), intervalo do estro a ocorrência da ovulação (39,9±12,3h), diâmetro do maior folículo (7,2±1,4) e número de ovulações (1,8±0,6). No Dia 1, 52,4% (11/21) apresentavam concentrações de progesterona 1ng/mL. O presente estudo permite concluir que o estro pode ser eficientemente sincronizado em cabras leiteiras com duas doses de PGF intervaladas em 10 dias. Novas pesquisas devem se realizadas para avaliar diferentes doses e momentos de utilização do hCG

Privação alimentar em pacu (Piaractus mesopotamicus): aspectos bioquímicos.

Resumo 658-1. 24º Reunião Anual da FeSBE

A new single nucleotide polymorphism in the ryanodine gene of chicken skeletal muscle.

Some genes affect meat quality in chickens. We looked for polymorphisms in the Gallus gallus α-RyR gene (homologous to RyR 1) that could be associated with PSE (pale, soft and exudative) meat. Because RyR genes are over 100,000 bp long and code for proteins with about 5000 amino acids, primers were designed to amplify a fragment of hotspot region 2, a region with a high density of mutations in other species. Total blood DNA was extracted from 50 birds, 25 that had PSE meat and 25 normal chickens. The DNA samples were amplified by PCR, cloned, sequenced, and used to identify single nucleotide polymorphisms (SNPs). The amplified fragment of α-RyR was 604 nucleotides in length; 181 nucleotides were similar to two exons from a hypothetical turkey cDNA sequence for α-RyR. A non-synonymous nucleotide substitution (G/A) was identified in at least one of the three sequenced clones obtained from nine animals, six PSE (HAL+) birds and three normal (HAL-) birds; they were heterozygous for this mutation