Genetic divergence within the monotypic tree genus <Emphasis Type="Italic">Platycarya</Emphasis> (Juglandaceae) and its implications for species’ past dynamics in subtropical China

Subtropical East Asia harbours a large plant diversity that is often attributed to allopatric speciation in this topographically complex region characterized by a relative climate stability. Here, we use observations of Platycarya, a widespread subtropical Asian tree genus, to explore the consequences of past climate stability on species’ evolutionary history in subtropical China. This genus has a controversial taxonomy: while it is now prevailingly treated as monotypic, two species have been originally described, Platycarya strobilacea and P. longipes. Previous information from species distribution models, fossil pollen data and genetic data based on chloroplast DNA (cpDNA) were integrated with newly obtained genetic data from the two putative species. We used both cpDNA (psbA-trnH and trnL-F intergenic spacers, including a partial trnL gene sequence) and nuclear markers. The latter included sequences of the internal transcribed spacer region (ITS1–5.8S–ITS2) of the nuclear ribosomal DNA and random genomic single nucleotide polymorphisms. Using these nuclear genetic markers, we found interspecific genetic divergence fitting with the ‘two species’ scenario and geographically structured intraspecific variation. Using cpDNA markers, we also found geographically structured intraspecific variation. Despite deep inter- and intraspecific genetic divergence, we detected genetic admixture in southwest China. Overall, our findings of genetic divergence within Platycarya support the hypothesis of allopatric speciation. However, episodes of population interconnection were identified, at least in southwest China, suggesting that the genus has had a dynamic population history.     

A Low Resistance Calcium/Reduced Titania Passivated Contact for High Efficiency Crystalline Silicon Solar Cells

Recent advances in the efficiency of crystalline silicon (c‐Si) solar cells have come through the implementation of passivated contacts that simultaneously reduce recombination and resistive losses within the contact structure. In this contribution, low resistivity passivated contacts are demonstrated based on reduced titania (TiO_x) contacted with the low work function metal, calcium (Ca). By using Ca as the overlying metal in the contact structure we are able to achieve a reduction in the contact resistivity of TiO_x passivated contacts of up to two orders of magnitude compared to previously reported data on Al/TiO_x contacts, allowing for the application of the Ca/TiO_x contact to n‐type c‐Si solar cells with partial rear contacts. Implementing this contact structure on the cell level results in a power conversion efficiency of 21.8% where the Ca/TiO_x contact comprises only ≈6% of the rear surface of the solar cell, an increase of 1.5% absolute compared to a similar device fabricated without the TiO_x interlayer.     

A Preliminary Study about the Potential Effects of Heavy Metals on the Human Male Reproductive Parameters in HIV-Infected Population in China

Due to the inconsistent effects of human immunodeficiency virus (HIV) on the human male reproduction in previous studies and the impacts of environmental exposures, such as heavy metals, on male reproduction receiving little attention in HIV-infected population, the aim of present study was to investigate whether heavy metals have potential effects on reproductive parameters in HIV-infected men. The current study assessed the associations between semen quality or serum hormone and concentration of the three heavy metal toxicants (lead (Pb), cadmium (Cd), and zinc (Zn)) in seminal, urine, and serum, and 50 HIV-infected men were recruited in the present study. Concentrations of Pb, Cd, and Zn were measured in three fluids by graphite furnace atomic absorption spectrophotometer. Semen analyses were performed according to World Health Organization criteria. Serum samples were analyzed for follicle-stimulating hormone, luteinizing hormone, and testosterone. HIV RNA viral load was determined by HIV virus loads kit. Spearman’s rank correlations were used for correlation analyses. The results showed that the concentrations of Pb, Cd, and Zn were significantly correlated with semen quality and serum hormone. HIV-1 virus loads were significantly associated with increased seminal Pb. However, HIV-1 virus loads were not statistically associated with semen quality and serum hormone. Our findings suggested that environmental heavy metals had potential effects on reproductive parameters in HIV-infected men in China.     

Impacts of sediment type on the performance and composition of submerged macrophyte communities

To restore deteriorated lake ecosystems, it is important to identify environmental factors that influence submerged macrophyte communities. While sediment is a critical environmental factor for submerged macrophytes and many studies have examined effects of sediment type on the growth of individual submerged macrophytes, very few have tested how sediment type affects the growth and species composition of submerged macrophyte communities. We constructed submerged macrophyte communities containing four co-occurring submerged macrophytes (Hydrilla verticillata, Myriophyllum spicatum, Ceratophyllum demersum and Chara fragilis) and subjected them to three sediment treatments, i.e., clay, a mixture of clay and quartz sand at a volume ratio of 1:1 and a mixture at a volume ratio of 1:4. Compared to the clay, the 1:1 mixture treatment greatly increased overall biomass, number of shoot nodes and shoot length of the community, but decreased its diversity. This was because it substantially promoted the growth of H. verticillata within the community, making it the most abundant species in the mixture sediment, but decreased that of M. spicatum and C. demersum. The sediment type had no significant effects on the growth of C. fragilis. As a primary nutrient source for plant growth, sediment type can have differential effects on various submerged macrophyte species and 1:1 mixture treatment could enhance the performance of the communities, increasing the overall biomass, number of shoot nodes and shoot length by 39.03%, 150.13% and 9.94%, respectively, compared to the clay treatment. Thus, measures should be taken to mediate the sediment condition to restore submerged macrophyte communities with different dominant species.     

Dynamic metabolic responses of brown planthoppers towards susceptible and resistant rice plants

Brown planthopper (Nilaparvata lugens Stål, BPH) causes huge economic losses in rice‐growing regions, and new strategies for combating BPH are required. To understand how BPHs respond towards BPH‐resistant plants, we systematically analysed the metabolic differences between BPHs feeding on the resistant and susceptible plants using NMR and GC‐FID/MS. We also measured the expression of some related genes involving glycolysis and biosyntheses of trehalose, amino acids, chitin and fatty acids using real‐time PCR. BPH metabonome was dominated by more than 60 metabolites including fatty acids, amino acids, carbohydrates, nucleosides/nucleotides and TCA cycle intermediates. After initial 12 h, BPHs feeding on the resistant plants had lower levels of amino acids, glucose, fatty acids and TCA cycle intermediates than on the susceptible ones. The levels of these metabolites recovered after 24 h feeding. This accompanied with increased level in trehalose, choline metabolites and nucleosides/nucleotides compared with BPH feeding on the susceptible plants. Decreased levels of BPH metabolites at the early feeding probably resulted from less BPH uptakes of sap from resistant plants and recovery of BPH metabolites at the later stage probably resulted from their adaptation to the adverse environment with their increased hopping frequency to ingest more sap together with contributions from yeast‐like symbionts in BPHs. Throughout 96 h, BPH feeding on the resistant plants showed significant up‐regulation of chitin synthase catalysing biosynthesis of chitin for insect exoskeleton, peritrophic membrane lining gut and tracheae. These findings provided useful metabolic information for understanding the BPH–rice interactions and perhaps for developing new BPH‐combating strategies.     

In Situ,Fast, High‐Temperature Synthesis of Nickel Nanoparticles in Reduced Graphene Oxide Matrix

For the first time, a fast heating–cooling process is reported for the synthesis of carbon‐coated nickel (Ni) nanoparticles on a reduced graphene oxide (RGO) matrix (nano‐Ni@C/RGO) as a high‐performance H₂O₂ fuel catalyst. The Joule heating temperature can reach up to ≈2400 K and the heating time can be less than 0.1 s. Ni microparticles with an average diameter of 2 µm can be directly converted into nanoparticles with an average diameter of 75 nm. The Ni nanoparticles embedded in RGO are evaluated for electro‐oxidation performance as a H₂O₂ fuel in a direct peroxide–peroxide fuel cell, which exhibits an electro‐oxidation current density of 602 mA cm^?2 at 0.2 V (vs Ag/AgCl), ≈150 times higher than the original Ni microparticles embedded in the RGO matrix (micro‐Ni/RGO). The high‐temperature, fast Joule heating process also leads to a 4–5 nm conformal carbon coating on the surface of the Ni nanoparticles, which anchors them to the RGO nanosheets and leads to an excellent catalytic stability. The newly developed nano‐Ni@C/RGO composites by Joule heating hold great promise for a range of emerging energy applications, including the advanced anode materials of fuel cells.