Search

Plants have evolved complex mechanisms to reprogram growth in response to drought stress. In herbaceous perennial plant species, the rhizome, which is normally an organ for propagation and food storage, can also support plant growth in stressful environments, and allows the plant to perennate and survive stress damage. However, the mechanisms that regulate rhizome growth in perennial herbs during abiotic stresses are unknown. Here, we identified a chrysanthemum (Chrysanthemum morifolium) DEAD-box RNA helicase gene, CmRH56 , that is specifically expressed in the rhizome shoot apex. Knock down of CmRH56 transcript levels decreased the number of rhizomes and enhanced drought stress tolerance. We determined that CmRH56 represses the expression of a putative gibberellin (GA) catabolic gene, GA2 oxidase6 (CmGA2ox6). Exogenous GA treatment and silencing of CmGA2ox6 resulted in more rhizomes. These results demonstrate that CmRH56 suppresses rhizome outgrowth under drought stress conditions by blocking GA biosynthesis. [ABSTRACT FROM AUTHOR]

Climatic warming is forcing species to shift their ranges poleward, which has been demonstrated for many taxa globally. Yet, the influence of habitat types on within- and among-species variations of distribution shifts has rarely been studied, especially during the non-breeding season. Here, we investigated habitat-specific shift distances of northern range margins and directions of the distribution center based on long-term data of overwintering birds in Finland. Specifically, we explored influences of habitat type, species' snow depth tolerance, species' climatic niche and habitat specialization on range shifts during the past 40 years in 81 bird species. Birds overwintering in arable land shifted more clearly toward north compared to birds of the same species in rural and forest habitats, while the northern range margin shift distances did not significantly differ among the habitat types. Range shifts were more linked with the species' snow depth tolerance rather than species' climatic niche. Snow depth tolerance of species was negatively associated with the eastward shift direction across all habitats, while we found habitat-specific patterns with snow depth for northward shift directions and northern margin shift distances. Species with stronger habitat specializations shifted more strongly toward north as compared to generalist species, whereas the climatic niche of bird species only marginally correlated with range shifts, so that cold-dwelling species shifted longer distances and more clearly eastward. Our study reveals habitat-specific patterns linked to snow conditions for overwintering boreal birds and highlights the importance of habitat availability and preference in climate driven range shifts. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the optimal lowest instrumented vertebra (LIV) in the treatment of Scheuermann kyphosis (SK) with different curve patterns. Methods: Fifty-two SK patients who underwent posterior surgery between January 2010 and December 2017 with a minimum follow-up of 2 years were retrospectively reviewed. Patients were divided into two groups based on the curve pattern: the Scheuermann thoracic kyphosis (STK group) or Scheuermann thoracolumbar kyphosis (STLK group). Based on the relationship between the sagittal stable vertebra (SSV) and LIV, both groups were further divided into the SSV group and SSV-1 group. Radiographic parameters, distal junctional kyphosis (DJK) incidence and SRS-22 questionnaire scores were evaluated. Results: In STK and STLK groups, there were no significant differences in most pre- and postoperative radiographic assessments between SSV and SSV-1 subgroups. DJK incidence showed no significant differences between groups during follow-up (P > 0.05). LIV-PSVL was significantly more negative in the SSV-1 group than that in the SSV group (P < 0.001). Within the SSV-1 group, patients with DJK showed a more negative LIV-PSVL (P = 0.039). Moderate correlation was observed between preoperative LIV-PSVL and DJK with a Spearman coefficient of − 0.474 (P = 0.035). Receiver operative characteristic curve analysis showed that the threshold value of preoperative LIV-PSVL to predict DJK was − 37.35 mm (area under the curve 0.882). Conclusion: Shorter fusion stopping at SSV-1 achieved comparable clinical outcomes and did not increase the risk of DJK for both STK and STLK patients. For patients whose preoperative LIV-PSVL < − 37.35 mm, extending fusion to SSV is an acceptable solution to prevent DJK. [ABSTRACT FROM AUTHOR]

Porous carbon, derived from biomass, has a high specific surface area and is one of the most attractive electrode materials for supercapacitors. Nonetheless, it is difficult to find a simple and efficient method to process inexpensive raw materials, which is also suitable for large-scale manufacture. This paper proposes a facile and scalable ball-milling combined with KOH chemical activation strategy to prepare the honeycomb-like porous carbon framework with high micropores and small dimensional mesopores from the peony seed shells (PS). Ball-milling technology was used to generate the necessary mechanical force to break the bulk biochar coming from the carbonization of PS into small pieces and increase the accessible surface area for the activation process. In addition, more ordered structures are transformed from sp3-hybridized carbon to sp2-hybridized carbon, which enhances the degree of graphitization for the obtained porous carbon. Furthermore, during the ball-milling and chemical activation process, the incorporation of oxygen atoms into the carbon base of as-prepared materials increases its hydrophilicity which facilitates a better interfacial contact between the hydrated electrolyte ions and the electrode surface in the process of charge and discharge. As a result, an as-fabricated supercapacitor, which is made of this highly porous carbon material, can reach a high specific capacitance (339 F g−1) at a current density of 1 A g−1. The other obtained key parameters for capacitors are also excellent: rate performance (260 F g−1 at 20 A g−1), cycling stability (95.2% capacitance retention after 10,000 cycles at a current density of 1 A g−1). In addition, a high energy density (29.6 Wh kg−1 at 180 W kg−1) can be achieved when the material is used in a 1.6 V Na2SO4 aqueous symmetrical supercapacitor. These results confirm that ball-milling (together with chemical activation) can successfully produce honeycomb-like porous carbon from peony seed shells. The developed electrode material has great potential to be applied in practical high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Cu matrix composites (CMCs) are widely employed for tribological applications such as in sliding bearings and electrical contact fields. However, the Cu matrix needs to be modified to improve its mechanical and tribological properties. In this study, CMCs reinforced with Mo 2 BC ceramic particles (10–30 wt%) are prepared via the spark plasma sintering (SPS) route method. In comparison with the plain Cu sample, when the content of the Mo 2 BC particles increased to 30 wt%, the Vickers hardness, yield strength, and tensile strength of CMCs increased by 196 %, 157 %, and 588 %, respectively. Fine grain and load transfer strengthening mechanism are considered the main strengthening mechanism. Introducing the Mo 2 BC ceramic effectively reduces friction and wear as well as the frictional noise vibration of CMCs. Incorporating Mo 2 BC ceramic into the Cu matrix can elevate the load-bearing ability, inhibiting mechanical and adhesive wear. In addition, the composite exhibits superior friction and wear properties as the content of Mo 2 BC ceramic increases gradually up to 30 wt%, where the friction coefficient and wear rate are as low as 0.35 and 3.25 × 10−6 mm3/Nm, respectively. A layer of tribo-film containing Fe 2 O 3 derived from the counterparts and induced by the tribo-oxidation reaction can provide a lubricating effect. Considering the superior mechanical and tribological properties, the as-prepared CMCs could be an attractive alternative material for sliding bearing fields. • Cu matrix composites reinforced with Mo 2 BC are successfully prepared. • Mechanical and tribological properties of Cu matrix composites are greatly improved. • The dominant strengthening mechanisms are fine-grain and load-transfer strengthening. • Mechanical and adhesive wear effects are obviously inhibited when Mo 2 BC is doped. • The generating tribo-oxide films can reduce friction and wear. [ABSTRACT FROM AUTHOR]