Duplicated Chromosome Segments in Maize (Zea mays L.): Further Evidence from Hexokinase Isozymes

The genetic control of hexokinase isozymes (ATP: d-hexose-6-phosphotransferase, E.C. 2.7.7.1, HEX) in maize (Zea mays L.) was studied by starch gel electrophoresis. Genetic analysis of a large number of inbred lines and crosses indicates that the major isozymes observed are encoded by two nuclear loci, designated Hexl and Hex2. Five active allozymes and one null variant are associated with Hexl, while Hex2 has nine active alleles in addition to a null variant. Alleles at both loci govern the presence of single bands, with no intragenic or intergenic heteromers visible, suggesting that maize HEX\u27s are active as monomers. Organelle preparations demonstrate that the products of both loci are cytosolic. All alleles, including the nulls, segregate normally in crosses. Vigorous and fertile plants were synthesized that were homozygous for null alleles at both loci, suggesting that other hexosephosphorylating enzymes exist in maize that are undetected with our assay conditions. Linkage analyses and crosses with B-A translocation stocks place Hexl on the short arm of chromosome 3, 27 centimorgans from Pgd2 (phosphogluconate dehydrogenase) and Hex2 on the long arm of chromosome 6, approximately 45 centimorgans from Pgdl. It is suggested that the parallel linkages among these two pairs of duplicated genes reflects an evolutionary history involving chromosome segment duplication or polyploidy

Suspicion of Motives Predicts Minorities' Responses to Positive Feedback in Interracial Interactions.

Strong social and legal norms in the United States discourage the overt expression of bias against ethnic and racial minorities, increasing the attributional ambiguity of Whites' positive behavior to ethnic minorities. Minorities who suspect that Whites' positive overtures toward minorities are motivated more by their fear of appearing racist than by egalitarian attitudes may regard positive feedback they receive from Whites as disingenuous. This may lead them to react to such feedback with feelings of uncertainty and threat. Three studies examined how suspicion of motives relates to ethnic minorities' responses to receiving positive feedback from a White peer or same-ethnicity peer (Experiment 1), to receiving feedback from a White peer that was positive or negative (Experiment 2), and to receiving positive feedback from a White peer who did or did not know their ethnicity (Experiment 3). As predicted, the more suspicious Latinas were of Whites' motives for behaving positively toward minorities in general, the more they regarded positive feedback from a White peer who knew their ethnicity as disingenuous and the more they reacted with cardiovascular reactivity characteristic of threat/avoidance, increased feelings of stress, heightened uncertainty, and decreased self-esteem. We discuss the implications for intergroup interactions of perceptions of Whites' motives for nonprejudiced behavior

Interrelation of the CdTe Grain Size, Postgrowth Processing, and Window Layer Selection on Solar Cell Performance.

Recent improvements to the CdTe solar cell device structure have focused on replacing the CdS window layer with a more transparent material to reduce parasitic absorption and increase Jsc, as well as incorporating selenium into the absorber layer to achieve a graded band gap. However, altering the CdTe device structure is nontrivial due to the interdependent nature of device processing steps. The choice of the window layer influences the grain structure of the CdTe layer, which in turn can affect the chloride treatment, which itself may contribute to intermixing between the window and absorber layers. This work studies three different device architectures in parallel, allowing for an in-depth comparison of processing conditions for CdTe solar cells grown on CdS, SnO2, and CdSe. Direct replacement of the CdS window layer with a wider band gap SnO2 layer is hindered by poor growth of the absorber, producing highly strained CdTe films and a weak junction. This is alleviated by inserting a CdSe layer between the SnO2 and CdTe, which improves the growth of CdTe and results in a graded CdSexTe1-x absorber layer. For each substrate, the CdTe deposition rate and postgrowth chloride treatment are systematically varied, highlighting the distinct processing requirements of each device structure

CSS Antimony Selenide Film Morphology and High Efficiency PV Devices

Knowledge of close-space sublimation (CSS) Sb 2 Se 3 growth conditions is vital for proper understanding of PV performance, and optimization of Sb 2 Se 3 devices. In this work, various growth parameters have been studied and the resulting Sb 2 Se 3 films have been characterized using SEM, XRD and optical transmission measurements, thus illustrating the desired properties for high device performance. PV devices were fabricated using TiO 2 as a window layer combined with P3HT or PTB7 as the hole transport material, resulting in V oc =0.42 V, J sc =33.4 mAcm -2 , FF = 43.2% and PCE = 6.06% for P3HT

Emerging inorganic solar cell efficiency tables (Version 1)

This paper presents the efficiency tables of materials considered as emerging inorganic absorbers for photovoltaic solar cell technologies. The materials collected in these tables are selected based on their progress in recent years, and their demonstrated potential as future photovoltaic absorbers. The first part of the paper consists of the criteria for the inclusion of the different technologies in this paper, the verification means used by the authors, and recommendation for measurement best practices. The second part details the highest world-class certified solar cell efficiencies, and the highest non-certified cases (some independently confirmed). The third part highlights the new entries including the record efficiencies, as well as new materials included in this version of the tables. The final part is dedicated to review a specific aspect of materials research that the authors consider of high relevance for the scientific community. In this version of the Efficiency tables, we are including an overview of the latest progress in theoretical methods for modeling of new photovoltaic absorber materials expected to be synthesized and confirmed in the near future. We hope that this emerging inorganic Solar Cell Efficiency Tables (Version 1) paper, as well as its future versions, will advance the field of emerging photovoltaic solar cells by summarizing the progress to date and outlining the future promising research directions