Non-Abelian Topological Phases and Their Quotient Relations in Acoustic Systems.

Non-Abelian topological phases (NATPs) exhibit enigmatic intrinsic physics distinct from well-established Abelian topological phases, while lacking straightforward configuration and manipulation, especially for classical waves. In this Letter, we exploit novel braiding-type couplings among a pair of triple-component acoustic dipoles, which act as functional elements with effective imaginary couplings. Sequencing them in one dimension allows us to generate acoustic NATPs in a compact yet time-reversal invariant Hermitian system. We further provide the whole phase diagram that encompasses all i, j, and k non-Abelian phases, and directly demonstrate their unique quotient relations via different end point states. Our NATPs based on real-space braiding may inspire the exploration of acoustic devices with non-commutative characters.

Enantioselective Deaminative Alkylation of Amino Acid Derivatives with Unactivated Olefins.

Herein, we report the first Ni-catalyzed enantioselective deaminative alkylation of amino acid and peptide derivatives with unactivated olefins. Key for success was the discovery of a new sterically encumbered bis(oxazoline) ligand backbone, thus offering a de novo technology for accessing enantioenriched sp3-sp3 linkages via sp3 C-N functionalization. Our protocol is distinguished by its broad scope and generality across a wide number of counterparts, even in the context of late-stage functionalization. In addition, an enantioselective deaminative remote hydroalkylation reaction of unactivated internal olefins is within reach, thus providing a useful entry point for forging enantioenriched sp3-sp3 centers at remote sp3 C-H sites.

Feature Ranking and Screening for Class-Imbalanced Metabolomics Data Based on Rank Aggregation Coupled with Re-Balance.

Feature screening is an important and challenging topic in current class-imbalance learning. Most of the existing feature screening algorithms in class-imbalance learning are based on filtering techniques. However, the variable rankings obtained by various filtering techniques are generally different, and this inconsistency among different variable ranking methods is usually ignored in practice. To address this problem, we propose a simple strategy called rank aggregation with re-balance (RAR) for finding key variables from class-imbalanced data. RAR fuses each rank to generate a synthetic rank that takes every ranking into account. The class-imbalanced data are modified via different re-sampling procedures, and RAR is performed in this balanced situation. Five class-imbalanced real datasets and their re-balanced ones are employed to test the RAR's performance, and RAR is compared with several popular feature screening methods. The result shows that RAR is highly competitive and almost better than single filtering screening in terms of several assessing metrics. Performing re-balanced pretreatment is hugely effective in rank aggregation when the data are class-imbalanced.

[Effects of nitrogen fertilizer reduction management on photosynthesis and chlorophyll fluorescence characteristics of sweetpotato]. / å‡æ°®è¿ç­¹å¯¹ç”˜è–¯å ‰åˆä½œç”¨å’Œå¶ç»¿ç´ è§å ‰ç‰¹æ€§çš„å½±å“.

Crop productivity depends on photosynthetic source capacity. Appropriate nitrogen (N) fertilizer management is beneficial for improving growth, photosynthetic capacity and thereby increasing crops yield. A two-year pot experiment was conducted with four N treatments, i.e., conventional basal application 100 kg N·hm-2 as control (FP), a total of 80 kg N·hm-2 applied either 100% at basal application (JS), 100% at tuber initiation stage (35 d after transplant, KS), 50% at basal application and 50% at tuber initiation stage (35 d after transplant, FS), to examine the effects of reduced nitrogen fertilizer combined with application methods on the photosynthesis and chlorophyll fluorescence characteristics of sweetpotato (Ipomoea batatas) during summer 2016 and 2017. The results showed that the conventional basal application of a reduced N rate decreased photosynthesis of sweetpotato during the final growth phases compared to conventional application, dressing application relatively delayed late-season leaf senescence as indicated by the increased net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci) and chlorophyll (Chl a+b) content during tuber expansion period. Split application of N fertilizer had noticeably higher Pn, gs, Ci and Chl a+b than other treatments. Furthermore, split application of N fertilizer had a significantly higher photochemical efficiency of photosystem 2 (Fv/Fm), quantum yield of electron transport (ΦPS2), and photochemical quenching co-efficient (qP), but lower initial fluorescence (Fo) and non-photochemical quenching coefficient (NPQ) during tuber expansion period. The improved photosynthesis by split N was due to both increased Fv/Fm with higher electron transfer rate and reduced thermal dissipation of light energy in the tuber expansion period. Results were consistent between two sweetpotato cultivars across years. The results indicated that one-time fertilization at basal or tuber initiation stage were not conducive to sweetpotato leaf photosynthesis. The split N application was more beneficial in terms of delaying late-season leaf senescence, extending leaf function period, enhancing photosynthesis and biomass production under reduced N application rate, which would be beneficial for sweetpotato yield.

[ONN]-type amine pyridine(s) phenolate-based oxovanadium(V) catalysts for ethylene homo- and copolymerization.

A series of oxovanadium(V) complexes containing amine pyridine(s) phenolate ligands [ONN] (2a-f) have been synthesized in high yields (68-83%) by reacting VO(O(n)Pr)3 with 1.0 equiv. of the ligands in CH2Cl2. These complexes were characterized by (1)H, (13)C and (51)V NMR spectroscopy and elemental analysis. X-ray structural analysis for 2a, 2c and 2d revealed that these complexes adopt a six-coordinate distorted octahedral geometry around the vanadium center in the solid state. Upon treatment with Et2AlCl and CCl3COOEt, these complexes displayed high catalytic activities for ethylene polymerization even at elevated reaction temperatures, depending on ligand structures. The resulting polymers possessed high molecular weight and unimodal molecular weight distributions, indicative of the formation of a single catalytically active species during the polymerization catalysis. Excitingly, these vanadium(V) complexes could efficiently promote ethylene/norbornene copolymerization. The observed catalytic activity for the copolymerization was higher than that for ethylene homopolymerization. Moreover, the molecular weights of the resulting copolymers increased upon increasing the norbornene feed. These results indicated that introducing a suitable amount of norbornene into the system not only could accelerate the polymerization rate but also could restrain chain transfer reactions to some extent.

Enhanced anticancer activity of gemcitabine coupling with conjugated linoleic acid against human breast cancer in vitro and in vivo.

Gemcitabine (GEM) is a nucleoside analog agent against a wide variety of tumors. To overcome its limitation of rapid metabolism in vivo that results in short circulation time and poor antitumor efficacy, a novel prodrug (CLA-GEM conjugate) has been developed through the covalent coupling of conjugated linoleic acid (CLA) to N(4)-amino group of GEM. The chemical structure of CLA-GEM conjugate was identified by NMR, FTIR and other methods. From in vitro tests, it was demonstrated that the linkage with CLA increased the plasma stability of GEM as well as the antitumor activity against human breast tumor cells (MCF-7). Importantly, it also altered the transport pattern of GEM across cell membrane (MCF-7 and MDA-MB-231), evidenced by the little effect of nucleoside transporter inhibitors (NBMPR and dipyridamole) on the IC(50) values of CLA-GEM, instead of the great effect on that of unmodified GEM. In vivo pharmacokinetic study showed that the CLA-GEM conjugate had a longer plasma half-life and a higher bioavailability compared to that of unmodified GEM. Significant stronger antitumor activity was observed in the nude mice xenografted MCF-7 breast tumor after treated with CLA-GEM than that of unmodified GEM, while no significant body weight loss was found in all treatments. In conclusion, the novel CLA-GEM conjugate prepared in this study would be a promising prodrug of gemcitabine for future clinical use.

Differentially expressed cDNAs at the early stage of banana ripening identified by suppression subtractive hybridization and cDNA microarray.

The banana (Musa acuminate L. AAA group) fruit undergoes a postharvest ripening process, which plays an important role in improving the quality and extending the shelf life of bananas. To manipulate postharvest banana ripening, a better understanding of the mechanism of postharvest ripening is necessary. The isolation of mRNA transcripts encoding proteins associated with the ripening process is a powerful tool for this purpose. To isolate differentially expressed genes at the early stage of postharvest banana ripening, a forward suppression subtractive hybridization (SSH) cDNA library was constructed. SSH was performed with cDNA from banana fruit on the day of harvest as the "driver" and cDNA from banana fruit 2 days postharvest (DPH) as the "tester." A total of 289 clones in the SSH library were sequenced. BLASTX results revealed that 191 cDNAs had significant sequence homologies with known sequences in the NCBI database. Of the 191 cDNAs, 138 were singletons, and 53 belonged to divergent clusters containing 2-8 sequences. The identified cDNAs encoded proteins involved in cellular processes such as: metabolism; protein destination and storage; protein synthesis; signal transduction; transport and intracellular traffic; cell structure, growth, and division; transcription and post-transcription; and disease and defense. To characterize differentially expressed cDNAs in the SSH library, cDNA microarray analysis was conducted. A total of 26 cDNAs in the 2-DPH banana fruit were found to be up-regulated and these results were confirmed by using reverse transcriptase-polymerase chain reaction (RT-PCR). The information generated in this study provides new clues to aid in the understanding of banana ripening.