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Forest gaps influence fungal community assembly in a weeping cypress forest
No full textThe forest gap crucially influences forest environments, but its effects on local fungal community assembly are not fully understood. In this study, the fungal community in a weeping cypress forest was investigated as a function of forest gap locations based on forest clearing, using amplicon sequencing of the ITS2 region. The results showed that the fungal community significantly varied with the variations in soil properties related to gap location. Deterministic processes played pivotal roles in fungal community assembly, which was mainly driven by the temperature, moisture, available nitrogen, and microbial carbon in soil. Beta diversity of the fungal community increased from the gap center to the closed canopy. The relative abundances of dominant orders such as Microascales, Sordariales, and Chaetothyriales regularly varied as a function of gap location, and they were potential indicators for different gap locations. Based on network analysis, gap locations caused distinct co-occurrence patterns of fungal communities. This study shed light on the roles of forest gaps in the assembly of local fungal communities and provided additional strategies to manage forest ecosystems
Flow controllable three-dimensional paper-based microfluidic analytical devices fabricated by 3D printing technology
No full textIn most cases, three-dimensional paper-based microfluidic analytical devices (3D-mu PADs) were fabricated manually by stacking or folding methods. For the first time, digital light processing stereolithography (DLP-SLA) 3D printing technology was adopted to automatically make 3D-mu PADs. In the fabrication process, a printing pause was set between two layers to allow paper to be placed in the resin tank. The resin on the fresh paper spontaneously bonded to the former cured paper layer during curing, thus realizing the automatic bonding and alignment between different layers of paper and avoiding the human participation and errors as in stacking and folding methods. There was a gap between two vertical aligned flow paths, therefore the liquid did not flow spontaneously from the upper layer to the lower layer. Most of the fluid flow in 3D-mu PADs was spontaneous or manually activated, which was not conducive to complex assays that require different regents to be delivered sequentially. Herein, we used an electric field or airflow to trigger the fluid flow and demonstrated the flow controllability by a proof-of-concept colorimetric assay. The limits of detection of glucose and albumin were 0.8 mM and 3.5 mu M, respectively, which were sufficient for clinical requirements. Given the characteristic of flow controllability, we believe that the proposed 3D-mu PADs have great potential to make paper-based complex assays automated and programmable. (C) 2019 Elsevier B.V. All rights reserved
Organocatalytic enantioselective sulfa-Michael addition of thiocarboxylic acids to beta-trifluoromethyl-alpha,beta-unsaturated ketones for the construction of stereogenic carbon center bearing a sulfur atom and a trifluoromethyl group
No full textAn organocatalyzed asymmetric sulfa-Michael addition of thiocarboxylic acids to beta-trifluoromethyl-alpha,beta-unsaturated ketones with a chiral bifunctional amine-squaramide as the catalyst is presented. A wide range of chiral ketone compounds bearing a sulfur atom and a trifluoromethyl group at the stereogenic carbon center could be obtained with excellent results (up to 99% yield, 97% ee) under mild conditions. The developed catalytic system is well-tolerated to both (E)-and (Z)-beta-trifluoromethylated-alpha,beta-unsaturated ketones. (C) 2019 Elsevier Ltd. All rights reserved
Tough Self-Healing Elastomers Based on the Host-Guest Interaction of Polycyclodextrin
No full textInspired by animal muscles, we developed a kind of tough elastomers combining high strength and high stretchability with autonomous self-healing capability. A key structural feature is the construction of a double network (DN) connected by the hydrogen bond and host-guest interactions. The first network is the classic elastomer polyacrylate matrix cross-linked by strong hydrogen bonding. The second network is formed through the host-guest interactions between polycyclodextrin and the adamantane (Ad) groups on the side of the polyacrylate chain. Supramolecular interactions between two networks make them miscible and interpenetrate in the molecular level and then can share the load as the sample was stretched. The host-guest interactions act not only as sacrificial bonds for energy dissipation but also as self-healing driving forces. The tensile strength of the DN elastomer reaches about 6.7 MPa and the strain is as high as about 950%. The DN elastomer can be easy to repair by touching the damaged surface together at ambient conditions when broken or cut. The recovered tensile strength can reach over 4.5 MPa, which is better than the most pristine strength of existing spontaneous self-healing elastomers
Potential short-term effects of yak excreta addition on peat soil gross nitrogen transformations of Zoige peatland under laboratory conditions
No full text牦牛放牧是若尔盖泥炭地一个普遍现象,牦牛排泄物直接返还于泥炭地.通过室内短期培养实验,利用~(15)N稳定同位素成对标记法结合马尔可夫链蒙特卡洛随机采样方法(MCMC)数值模型,研究牦牛排泄物输入对泥炭地土壤氮初级转化速率的影响.结果表明,施粪组土壤NH_4~+-N的总生产速率(17.49 mg kg~(-1) d~(-1))约为对照组的2倍(8.94 mg kg~(-1)d~(-1)),其中有机氮的矿化作用是其主要来源途径.两种处理土壤NH_4~+-N的总消耗速率均大于各自总生产速率,其中被微生物的同化作用固定于难分解有机氮库中的NH4+-N分别占其总消耗量的70%(对照组)和91%(施粪组).微生物的自养硝化作用是两种处理土壤NO_3~--N的主要产生途径,分别为5.31 mg kg~(-1) d~(-1)(对照组)和2.13 mg kg~(-1) d~(-1)(施粪组),均占各自NO_3~--N总生产量的80%以上.对照组和施粪组土壤NO_3~--N的主要利用方式均为NO_3~--N的异化还原作用,分别为0.20和0.24 mg kg~(-1) d~(-1).施粪组土壤N_2O累积排放量最高,为7.81 mg kg~(-1),对照组次之,为6.08 mg kg~(-1),施尿组最少,为3.04 mgkg~(-1).施粪和施尿使土壤CH_4累积排放量分别增加了2.08和9.49 mg kg~(-1).施粪组和施尿组土壤CO_2累计排放量分别为对照组(145.17 mg kg~(-1))的3.89倍和22.63倍.总体来说,牦牛粪便输入通过促进土壤有机氮的矿化作用、抑制微生物的自养硝化作用以及促进NO_3~--N的异化还原作用,提高了土壤的供氮能力和减少了NO_3~--N的淋溶风险
Diastereoselective construction of pyrrolo[2,1-a]isoquinoline-based bispirooxindoles through a three-component [3+2] cycloaddition
No full textAn efficient three-component one-pot [3 + 2] cycloaddition of isatins, 1,2,3,4-tetrahydroisoquinolines and methyleneindolinones has been developed. This reaction proceeded in a highly diastereoselective manner to afford a wide range of pyrrolo[1,2-a]isoquinoline-based bispirooxindoles in up to 91% yields. Additionally, a gram-scale experiment and some chemical transformations were conducted
Primula luteoflora (Primulaceae), a new species from Sichuan, China
No full textPrimula luteoflora, a new species of Primulaceae from Sichuan, China, is described and illustrated here. It is morphologically assigned to Primula sect. Petiolares subsect. Davidii, characterized by the leaves firmly papery or leathery, with adaxially impressed veins and reticulate veins distinctly raised abaxially. However, the new species is distinguished by its leaf size, number of lateral veins, glabrous scape, number of flowers and yellow flowers
The Tryptophan decarboxylase 1 Gene From Aegilops variabilis No. 1 Regulate the Resistance Against Cereal Cyst Nematode by Altering the Downstream Secondary Metabolite Contents Rather Than Auxin Synthesis
No full textCereal cyst nematode (CCN, Heterodera avenae) is a most important pathogen of wheat and causes tremendous yield loss annually over the world. Since the lack of resistance materials among wheat cultivars, identification and characterization of the resistance-related genes from the relatives of wheat is a necessary and efficient way. As a close relative of wheat with high resistance against CCN, Aegilops variabilis No. 1 is believed to be a valuable source for wheat breeding against this devastating disease. However so far, very few resistance-associated genes have been characterized from this species. In this study, we present that the tryptophan decarboxylase genes from Ae. variabilis No. 1 (AeVTDC1 and AeVTDC2) were both induced by CCN juveniles at the early stage of resistance response (30 h post-inoculation), with AeVTDC1 more sensitive to CCN infection than AeVTDC2. Silencing of AeVTDC1 led to compromised immunity to CCN with more CCN intrusion into roots; while overexpression AeVTDC1 in Nicotiana tabacum dramatically enhanced the resistance of plants by reducing the knots formed on roots. Metabolism analysis showed that the contents of secondary metabolites with activity of resistance to varied pathogens correlated with the expression level of AeVTDC1 in both Ae. variabilis No. 1 and the transgenic tobacco plants. In addition, the content of IAA was not affected by either silencing or overexpressing of AeVTDC1. Hence, our research provided AeVTDC1 a valuable target that mediates resistance to CCN and root knot nematode (RKN, Meloidogyne naasi) without influencing the auxin biosynthesis
A new species of Eriobotrya (Rosaceae) from Con Dao National Park, southern Vietnam
No full textWe describe a distinctive new species of Eriobotrya condaoensis (Rosaceae) from Con Dao National Park, Ba Ria-Vung Tau Province, southern Vietnam, based on both morphological and molecular evidences. The new species is characterized by leaf blade oblong-oblanceolate, 8-12 x 4-6 cm, leaf margins crenate. both surface glabrous, secondary veins 6-7 pairs, bracts apically dentate and persistent, flowers sessile and yellowish, hypanthium funnel-shaped and brown tomentose, petals elliptic and 6-7 x 4-5 mm long, styles 2, free at base and 5-6 mm long, and ovary glabrous. Morphological characters and phylogenetic analysis based on nrDNA ITS sequences confirmed the distinctiveness of this new species in the genus
Enhancement of osteogenesis using a novel porous hydroxyapatite scaffold in vivo and vitro
No full textThe repair of large maxillofacial bony defects using regular scaffolds is restricted by the osteogenic effect. It was postulated that a novel porous hydroxyapatite (HA) scaffolds with a 25-30 mu m groove structure (HAG) may counter this limitation. In this study we evaluated the biocompatibility of HAG scaffolds both in vitro and in vivo in beagle dogs by investigating the enhancement of scaffolds bioactivity and osteogenesis. Compared with a regular HA scaffolds, the HAG scaffolds significantly promoted human placenta-derived mesenchymal stem cell (hPMSC) osteogenic differentiation and the maturation of osteoblasts. This is achieved by increasing protein adsorption, as well as promoting directed growth and expression of osteogenic genes in vitro. The compressive strength of HAG scaffolds was significantly greater than HA in both dorsal muscle and the mandibular distraction area after in vivo implantation, with hematoxylin and eosin staining demonstrating new bone formation and vasculogenesis. Immunochemical staining and micro-CT scanning demonstrated increased expression of osteogenic factors (BMP2, OCN and COL-1) and bone density in the HAG scaffolds compared with HA. Based on the above results, we conclude that HAG scaffolds that have a groove structure induce greater osteogenesis and possess improved ostoegenesis which could be utilized in the clinical treatment