bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochar prepared at different pyrolysis temperatures affects urea-nitrogen immobilization and N2O emissions in paddy fields
Authors: Gao Jiping , Zhao Yanze , Zhang Wenzhong , Sui Yanghui , Jin Dandan , Xin Wei , Yi Jun , He Dawei 
Published: June 2019

Background
Food safety has become a major issue, with serious environmental pollution resulting from losses of nitrogen (N) fertilizers. N is a key element for plant growth and is often one of the most important yield-limiting nutrients in paddy soil. Urea-N immobilization is an important process for restoring the levels of soil nutrient depleted by rice production and sustaining productivity. The benefits of biochar application include improved soil fertility, altered N dynamics, and reduced nutrient leaching. However, due to high variability in the quality of biochar, the responses of N loss and rice productivity to biochar amendments, especially those prepared at different pyrolysis temperatures, are still unclear. The main objectives of the present study were to examine the effects of biochar prepared at different pyrolysis temperatures on fertilizer N immobilization in paddy soil and explore the underlying mechanisms.

Methods
Two biochar samples were prepared by pyrolysis of maize straw at 400 °C (B400) and 700 °C (B700), respectively. The biochar was applied to paddy soil at three rates (0, 0.7, and 2.1%, w/w), with or without N fertilization (0, 168, and 210 kg N ha–1). Pot experiments were performed to determine nitrous oxide (N2O) emissions and 15N recovery from paddy soil using a 15N tracer across the rice growing season.

Results
Compared with the non-biochar control, biochar significantly decreased soil bulk density while increasing soil porosity, irrespective of pyrolysis temperature and N fertilizer level. Under B400 and B700, a high biochar rate decreased N loss rate to 66.42 and 68.90%, whereas a high N level increased it to 77.21 and 76.99%, respectively. Biochar also markedly decreased N2O emissions to 1.06 (B400) and 0.75 kg ha−1 (B700); low-N treatment caused a decrease in N2O emissions under B400, but this decrease was not observed under B700. An application rate of biochar of 2.1% plus 210 kg ha−1 N fertilizer substantially decreased the N fertilizer-induced N2O emission factor under B400, whereas under B700 no significant difference was observed. Biochar combined with N fertilizer treatment decreased rice biomass and grain yield by an average of 51.55 and 23.90 g pot–1, respectively, but the yield reduction under B700 was lower than under B400.

Conclusion
Irrespective of pyrolysis temperature, biochar had a positive effect on residual soil 15N content, while it negatively affected the 15N recovery of rice, N2O emissions from soil, rice biomass, and grain yield in the first year. Generally, a high application rate of biochar prepared at high or low pyrolysis temperature reduced the N fertilizer-induced N2O emission factor considerably. These biochar effects were dependent on N fertilizer level, biochar application rate, and their interactions.
Impact of Yam Postharvest Activities on Standard of Living of Yam Farming Households in North-East Zone of Benue State, Nigeria
Authors: Agba Solomon Arumun , Ode Idu , Ugbem Comfort , Nwafor Solomon Chimela 
Published: June 2019

Aims: The aim of the study was to identify postharvest activities of yam farming households in North-East Zone of Benue State, Nigeria and to assess the impact of losses from the yam postharvest activities on standard of living of yam farming households in North-East Zone of Benue State, Nigeria.
Study Design: Survey research design was adopted for the study.
Place and Duration of Study: North-East Zone of Benue State, Nigeria.
Methodology: The study purposively selected three (3) local government areas (Ukum, Katsina-Ala and Logo) that are most prominent in yam production in North-East Zone of Benue State from where a total sample size of two hundred and four (204) yam farming households were drawn from three local government areas of North-East Zone of Benue state using multi-stage cluster sampling technique.
Results: Almost all the farmers 99% (202) store their yams and majority of the farmers are also involved in yam marketing. Majority of the famers 84% (172) always need to transport their yams. This could be in order to access distant markets which make for more gain. The few who do not need to transport their produce could be those who sale at farm gates. This could also be the reason why only a few 64% (130) majority take time to sort, grade and clean their produce. With the computed f-statistic value of 512.110 which was significantly higher than the tabulated f-value of 16.26 at 1% level of significance and 5.05 at 5% level of significance, therefore, the null hypothesis was rejected. This implies that, yam loss from yam postharvest activities noted above has a significant negative impact on the standard of living of yam farming households in the study area by reducing their household income (99%), affecting their access to health care services (89%), access to education (64%), access to good housing (84%) and access to sufficient quality food (98%).
Conclusion: The study thus concludes that, yam loss during postharvest activities such as: yam handling, yam storage, yam transportation, yam sorting / grading / cleaning and yam marketing has significant negative impact on the standard of living of yam farming households in the study area, by reducing their household income, affecting their access to health care services, access to education, access to good housing and access to sufficient quality food. The study recommends communication of knowledge on modern yam storage methods to yam farmers in the study area by agricultural extension agents and building of yam processing factories in the study area so as to add economic value to yam and consequently improve the standard of living of yam farming households in the study area.
Larvicidal Activity of Two Cymbopogon Species Leaf Extracts and Essential Oils against Anopheles gambiae Gilles (Diptera: Culicidae)
Authors: Batti Aurore Christelle Sengue , Younoussa Lame , Nukenine Elias Nchiwan , Oumarou Mallam Kary , Fomena Abraham 
Published: June 2019

Aims: The present investigation aimed to assess the toxic effect of hexane, acetone and methanol extracts of Cymbopogon citratus and Cymbopogon giganteus against 3rd and 4th instar of Anopheles gambiae larvae under laboratory conditions.
Place and Duration of Study: Plant products were extracted from November 2017 to February 2018 in the Chemistry laboratory, while the larvicidal tests were conducted from April to June 2018 in the laboratory of Applied Zoology of the Faculty of Science, University of Ngaoundere, Cameroon.
Methodology: Twenty five (25) 3rd and 4th instars of An. gambiae were subjected to methanol, acetone and methanol plant extracts of the two plants at doses of 1000, 500, 250 and 125 mg/L each while their essential oils were tested at concentrations of 200, 100, 50 and 25 mg/L. Dichlovos tested at the recommended dose of 1000 mg/L was performed as positive control while 1mL of tween-80 in 99 mL of natural breeding site water was used as negative control. Larval mortality was recorded after 24 h post treatment for plant extracts and after 1, 6, 12, 18 and 24 h post-exposure for plant essential oils.
Results: At the highest concentration of 1000 mg/L, C. citratus extract caused 100% mortality of mosquito larvae while 84, 81 and 88% mortality of larvae were recorded with hexane, acetone and methanol leaf extract of C. giganteus, respectively. C. citratus (LC50=58.32 mg/L) and C. giganteus (LC50=372.36 mg/L) hexane extracts were more potent than acetone and methanol extracts of the plants. C. citratus extracts were the most effective against larvae compared to C. giganteus extracts. Essential oil of C. citratus (LC50=27.98 mg/L after 1h) was also the most toxic on mosquito larvae compared to C. giganteus (LC50=180.07 mg/L after 1h) essential oil.
Conclusion: C. citratus plant and specially its hexane extract and essential oil could be taken into consideration as a new source of botanical insecticide and may be used in the mosquito control programs for An. gambiae larvae elimination in their breeding sites.
Comparative Study of Herbicides for Pre-Emergence Weed Control in Maize (Zea mays L.) in Derived Savanna of Nigeria
Authors: Aluko O. A. 
Published: June 2019

Aims: To evaluate and compare the efficiency of candidate herbicides and increase the latitude of herbicides for pre-emergence weed control in maize.
Study Design: Randomized Complete Block Design, with three replicates was used in the study.
Place and Duration of the Study: Candidate herbicides were obtained Rainbow Nig. Limited for evaluation. The study was carried out between June – September, 2014 and 2015 at Ibadan (0.7.38N; 003.84E) and Ilora (07.81N; 003.82E) research stations of the Institute of Agricultural Research and Training, Obafemi Awolowo University, Ibadan.
Methodology: Weed flora composition was taken with 1sqm quadrat placed randomly before land preparation. Acetochlor 500 g/L, Acetochlor 900 g/L, Metholachlor 720 g and Ametryn 80 WP were applied randomly at three rates of active ingredient (a.i) at maize sowing, while Atrazine (reference), weed-free and weedy check were the control. Agronomic and weed data were taken, analysed and means separated using Duncans Multiple Range Test (DMRT) at p≤ 0.05.
Results: Result showed that weed flora composition before land preparation was dominated by annual weeds {broadleaves (80%) and grass (20%)}. At 6 weeks after sowing (WAS), weed flora composition comprised of 8% spiderwort, 8% sedge, 25% grass weeds and 59% broadleaf weed species. Weed flora dynamics after treatments application might have been influenced by types of herbicides, herbicidal activities and previous cultural practices. Herbicides application resultantly increased plant height (50%) and grain yield (46 - 60%) relative to plant height in weedy check at both locations. These might have accrued from minimal weed interference hence, high weed control efficiency (WCE) recorded in herbicides applied (WCE ≥80%) and significant reduction in cumulative weed dry matter of about 80%.
Conclusion: Herbicides applied significantly reduced weed growth and enhanced maize grain yield. Notwithstanding, investigation of the benefit cost ratio and the environmental impact assessment of herbicides applied are imperative for sustainability of maize production and agro-ecology.
Relative importance of landscape and species characteristics on extinction debt, immigration credit and relaxation time after habitat turnover
Authors: Lalechère Etienne , Archaux Frédéric , Jabot Franck 
Published: June 2019

AbstractHabitat turnover concomitantly causes destruction and creation of habitat patches. Following such a perturbation, metapopulations harbor either an extinction debt or an immigration credit, that is the future decrease or increase in population numbers due to this disturbance. Extinction debt and immigration credit are rarely considered simultaneously and disentangled from the relaxation time (time to new equilibrium). In this contribution, we test the relative importance of two potential drivers of time‐delayed metapopulation dynamics: the spatial configuration of the habitat turnover and species dispersal ability. We provide a simulation‐based investigation projecting metapopulation dynamics following habitat turnover in virtual landscapes. We consider two virtual species (a short‐distance and a long‐distance disperser) and five scenarios of habitat turnover depending on net habitat loss or gain and habitat aggregation. Our analyses reveal that (a) the main determinant of the magnitude of the extinction debt or immigration credit is the net change in total habitat area, followed by species dispersal distance and finally by the post‐turnover habitat aggregation; (b) relaxation time weakly depends on the magnitude of the immigration credit or of the extinction debt; (c) the main determinant of relaxation time is dispersal distance followed by the net change in total habitat area and finally by the post‐turnover habitat aggregation. These results shed light on the relative importance of dispersal ability and habitat turnover spatial structure on the components of time‐delayed metapopulation dynamics.
Trypanosoma brucei centrin5 is enriched in the flagellum and interacts with other centrins in a calcium‐dependent manner
Authors: Shan Fangzhen , Yang Xiao , Diwu Yating , Ma Haoyu , Tu Xiaoming 
Published: June 2019

Centrin is an evolutionarily conserved EF‐hand‐containing protein, which is present in eukaryotic organisms as diverse as algae, yeast, and humans. Centrins are associated with the microtubule‐organizing center and with centrosome‐related structures, such as basal bodies in flagellar and ciliated cells, and the spindle pole body in yeast. Five centrin genes have been identified in Trypanosoma brucei (T. brucei), a protozoan parasite that causes sleeping sickness in humans and nagana in cattle in sub‐Saharan Africa. In the present study, we identified that centrin5 of T. brucei (TbCentrin5) is localized throughout the cytosol and nucleus and enriched in the flagellum. We further identified that TbCentrin5 binds Ca2+ ions with a high affinity and constructed a model of TbCentrin5 bound by Ca2+ ions. Meanwhile, we observed that TbCentrin5 interacts with TbCentrin1, TbCentrin3, and TbCentrin4 and that the interactions are Ca2+‐dependent, suggesting that TbCentrin5 is able to form different complexes with other TbCentrins to participate in relevant cellular processes. Our study provides a foundation for better understanding of the biological roles of TbCentrin5.
Precious‐Metal‐Free Electrocatalysts for Activation of Hydrogen Evolution with Nonmetallic Electron Donor: Chemical Composition Controllable Phosphorous Doped Vanadium Carbide MXene
Authors: Yoon Yeoheung , Tiwari Anand P. , Choi Min , Novak Travis G. , Song Wooseok , Chang Hyunju , Zyung Taehyoung , Lee Sun Sook , Jeon Seokwoo , An Ki‐Seok 
Published: June 2019

AbstractThe insufficient strategies to improve electronic transport, the poor intrinsic chemical activities, and limited active site densities are all factors inhibiting MXenes from their electrocatalytic applications in terms of hydrogen production. Herein, these limitations are overcome by tunable interfacial chemical doping with a nonmetallic electron donor, i.e., phosphorization through simple heat‐treatment with triphenyl phosphine (TPP) as a phosphorous source in 2D vanadium carbide MXene. Through this process, substitution, and/or doping of phosphorous occurs at the basal plane with controllable chemical compositions (3.83–4.84 at%). Density functional theory (DFT) calculations demonstrate that the PC bonding shows the lowest surface formation energy (ΔGSurf) of 0.027 eV Å−2 and Gibbs free energy (ΔGH) of –0.02 eV, whereas others such as P‐oxide and PV (phosphide) show highly positive ΔGH. The P3–V2CTx treated at 500 °C shows the highest concentration of PC bonds, and exhibits the lowest onset overpotential of –28 mV, Tafel slope of 74 mV dec−1, and the smallest overpotential of ‐163 mV at 10 mA cm−2 in 0.5 m H2SO4. The first strategy for electrocatalytically accelerating hydrogen evolution activity of V2CTx MXene by simple interfacial doping will open the possibility of manipulating the catalytic performance of various MXenes.
Bis(imidazolidine)pyridine‐CoCl2: A Novel, Catalytically Active Neutral Complex for Asymmetric Michael Reaction of 1,3‐Carbonyl Compounds with Nitroalkenes
Authors: Arai Takayoshi , Iimori Yuko , Shirasugi Mayu , Shinohara Ryota , Takagi Yuri , Suzuki Takumi , Ma Junma , Kuwano Satoru , Masu Hyuma 
Published: June 2019

AbstractA neutral bis(imidazolidine)pyridine (PyBidine)‐CoCl2 complex showed catalytic activity for the Michael reaction of malonates with nitroalkenes. The results indicated that a weak amine base aided enolate formation from the neutral complex, in which the N−H proton of the imidazolidine ligand played a significant role.magnified image
An environmentally friendly FeTiSOx catalyst with a broad operation‐temperature window for the NH3‐SCR of NOx
Authors: Song Lei , Ma Kui , Tian Wen , Ji Junyi , Liu Changjun , Tang Siyang , Jiang Wei , Yue Hairong , Liang Bin 
Published: June 2019

AbstractA novel FeTiSOx catalyst prepared by a simple hydrolysis coprecipitation method was used for the selective catalytic reduction (SCR) of NOx with NH3, which exhibited high catalytic activity (NOx conversion of >97% and N2 selectivity of >95%) and tolerance for both H2O and SO2 at a broad temperature window of ~325–475°C. The characterization results showed that the formation of Fe–O–Ti and Fe–O–S species could significantly enhance the acidic sites of the catalyst, which play an important role in NH3 absorption and their catalytic activity. The Fe3+ ions in the bulk anatase TiO2 could significantly enhance the redox properties for the SCR reaction and suppress the side reaction of NH3 oxidation to NO or N2O. In addition, the reaction mechanism was discussed based on in situ diffuse reflectance infrared Fourier transform spectroscopy measurements and kinetic investigation, indicating that the reaction was dominated by the Eley–Rideal mechanism over the FeTiSOx catalyst.
Intraspecific polyploidy correlates with colonization by arbuscular mycorrhizal fungi in Heuchera cylindrica
Authors: Anneberg Thomas J. , Segraves Kari A. 
Published: June 2019

PremisePolyploidy is known to cause physiological changes in plants which, in turn, can affect species interactions. One major physiological change predicted in polyploid plants is a heightened demand for growth‐limiting nutrients. Consequently, we expect polyploidy to cause an increased reliance on the belowground mutualists that supply these growth‐limiting nutrients. An important first step in investigating how polyploidy affects nutritional mutualisms in plants, then, is to characterize differences in the rate at which diploids and polyploids interact with belowground mutualists.MethodsWe used Heuchera cylindrica (Saxifragaceae) to test how polyploidy influences interactions with arbuscular mycorrhizal fungi (AMF). Here we first confirmed the presence of AMF in H. cylindrica, and then we used field‐collected specimens to quantify and compare the presence of AMF structures while controlling for site‐specific variation.ResultsTetraploids had higher colonization rates as measured by total, hyphal, and nutritional‐exchange structures; however, we found that diploids and tetraploids did not differ in vesicle colonization rates.ConclusionsThe results suggest that polyploidy may alter belowground nutritional mutualisms with plants. Because colonization by nutritional‐exchange structures was higher in polyploids but vesicle colonization was not, polyploids might form stronger associations with their AMF partners. Controlled experiments are necessary to test whether this pattern is driven by the direct effect of polyploidy on AMF colonization.
Effects of maternal source and progeny microhabitat on natural selection and population dynamics in Alliaria petiolata
Authors: Stinson Kristina , Carley Lauren , Hancock Laura , Donohue Kathleen 
Published: June 2019

PremiseThe success or failure of propagules in contrasting microhabitats may play a role in biological invasion. We tested for variation in demographic performance and phenotypic trait expression during invasion by Alliaria petiolata in different microhabitats.MethodsWe performed a reciprocal transplant experiment with Alliaria petiolata from edge, intermediate, and forest understory microhabitats to determine the roles of the environment and maternal source on traits, fecundity, population growth rates (λ), and selection.ResultsObservations of in situ populations show that edge populations had the highest density and reproductive output, and forest populations had the lowest. In experimental populations, population growth rates and reproductive output were highest in the edge, and the intermediate habitat had the lowest germination and juvenile survival. Traits exhibited phenotypic plasticity in response to microhabitat, but that plasticity was not adaptive. There were few effects of maternal source location on fitness components or traits.ConclusionsAlliaria petiolata appears to be viable, or nearly so, in all three microhabitat types, with edge populations likely providing seed to the other microhabitats. The intermediate microhabitat may filter propagules at the seed stage, but discrepancies between in situ observations and experimental transplants preclude clear conclusions about the role of each microhabitat in niche expansion. However, edge microhabitats show the highest seed output in both analyses, suggesting that managing edge habitats might reduce spread to the forest understory.
Molecular and Structural Characterization of a Promiscuous C‐Glycosyltransferase from Trollius chinensis
Authors: He Jun‐Bin , Zhao Peng , Hu Zhi‐Min , Liu Shuang , Kuang Yi , Zhang Meng , Li Bin , Yun Cai‐Hong , Qiao Xue , Ye Min 
Published: June 2019

AbstractHerein, the catalytic promiscuity of TcCGT1, a new C‐glycosyltransferase (CGT) from the medicinal plant Trollius chinensis is explored. TcCGT1 could efficiently and regio‐specifically catalyze the 8‐C‐glycosylation of 36 flavones and other flavonoids and could also catalyze the O‐glycosylation of diverse phenolics. The crystal structure of TcCGT1 in complex with uridine diphosphate was determined at 1.85 Å resolution. Molecular docking revealed a new model for the catalytic mechanism of TcCGT1, which is initiated by the spontaneous deprotonation of the substrate. The spacious binding pocket explains the substrate promiscuity, and the binding pose of the substrate determines C‐ or O‐glycosylation activity. Site‐directed mutagenesis at two residues (I94E and G284K) switched C‐ to O‐glycosylation. TcCGT1 is the first plant CGT with a crystal structure and the first flavone 8‐C‐glycosyltransferase described. This provides a basis for designing efficient glycosylation biocatalysts.
Transition‐Metal‐Free Hydrogen Autotransfer: Diastereoselective N‐Alkylation of Amines with Racemic Alcohols
Authors: Xiao Miao , Yue Xin , Xu Ruirui , Tang Weijun , Xue Dong , Li Chaoqun , Lei Ming , Xiao Jianliang , Wang Chao 
Published: June 2019

AbstractA practical method for the synthesis of α‐chiral amines by alkylation of amines with alcohols in the absence of any transition‐metal catalysts has been developed. Under the co‐catalysis of a ketone and NaOH, racemic secondary alcohols reacted with Ellman's chiral tert‐butanesulfinamide by a hydrogen autotransfer process to afford chiral amines with high diastereoselectivities (up to >99:1). Broad substrate scope and up to a 10 gram scale production of chiral amines were demonstrated. The method was applied to the synthesis of chiral deuterium‐labelled amines with high deuterium incorporation and optical purity, including examples of chiral deuterated drugs. The configuration of amine products is found to be determined solely by the configuration of the chiral tert‐butanesulfinamide regardless of that of alcohols, and this is corroborated by DFT calculations. Further mechanistic studies showed that the reaction is initiated by the ketone catalyst and involves a transition state similar to that proposed for the Meerwein–Ponndorf–Verley (MPV) reduction, and importantly, it is the interaction of the sodium cation of the base with both the nitrogen and oxygen atoms of the sulfinamide moiety that makes feasible, and determines the diastereoselectivity of, the reaction.