11 research outputs found
Responses of sequential and hierarchical phenological events to warming and cooling in alpine meadows
Organisms' life cycles consist of hierarchical stages, from a single phenological stage (for example, flowering within a season), to vegetative and reproductive phases, to the total lifespan of the individual. Yet phenological events are typically studied in isolation, limiting our understanding of life history responses to climate change. Here, we reciprocally transfer plant communities along an elevation gradient to investigate plastic changes in the duration of sequential phenological events for six alpine species. We show that prolonged flowering leads to longer reproductive phases and activity periods when plants are moved to warmer locations. In contrast, shorter post-fruiting leaf and flowering stages led to shorter vegetative and reproductive phases, respectively, which resulted in shorter activity periods when plants were moved to cooler conditions. Therefore, phenological responses to warming and cooling do not simply mirror one another in the opposite direction, and low temperature may limit reproductive allocation in the alpine region
Terbium–Aspartic Acid Nanocrystals with Chirality-Dependent Tunable Fluorescent Properties
Terbium–aspartic
acid (Tb–Asp) nanocrystals with
chirality-dependent tunable fluorescent properties can be synthesized
through a facile synthesis method through the coordination between
Tb and Asp. Asp with different chirality (dextrorotation/d and levogyration/l) changes the stability of the coordination
center following fluorescent absorption/emission ability differences.
Compared with l-Asp, d-Asp can coordinate Tb to
form a more stable center, following the higher quantum yield and
longer fluorescence life. Fluorescence intensity of Tb–Asp
linearly increases with increase ratio of d-Asp in the mixed
chirality Tb–Asp system, and the fluorescent properties of
Tb–Asp nanocrystals can be tuned by adjusting the chirality
ratio. Tb–Asp nanocrystals possess many advantage, such as
high biocompatibility, without any color in visible light irradiation,
monodispersion with very small size, and long fluorescent life. Those
characteristics will give them great potential in many application
fields, such as low-cost antifake markers and advertisements using
inkjet printers or for molds when dispersed in polydimethylsiloxane.
In addition, europium can also be used to synthesize Eu–Asp
nanoparticles. Importantly, the facile, low-cost, high-yield, mass-productive
“green” process provides enormous advantages for synthesis
and application of fluorescent nanocrystals, which will have great
impact in nanomaterial technology
Polylactic Acid Nanopillar Array-Driven Osteogenic Differentiation of Human Adipose-Derived Stem Cells Determined by Pillar Diameter
Numerous studies
have determined that physical cues, especially
the nanotopography of materials, play key roles in directing stem
cell differentiation. However, most research on nanoarrays for stem
cell fate regulation is based on nonbiodegradable materials, such
as silicon wafers, TiO<sub>2</sub>, and polyÂ(methyl methacrylate),
which are rarely used as tissue engineering biomaterials. In this
study, we prepared biodegradable polylactic acid (PLA) nanopillar
arrays with different diameters but the same center-to-center distance
using a series of anodic aluminum oxide nanowell arrays as templates.
Human adipose-derived stem cells (hADSCs) were selected to investigate
the effect of the diameter of PLA nanopillar arrays on stem cell differentiation.
By culturing hADSCs without the assistance of any growth factors or
osteogenic-induced media, the differentiation tendencies of hADSCs
on the nanopillar arrays were assessed at the gene and protein levels.
The assessment results suggested that the osteogenic differentiation
of hADSCs can be driven by nanopillar arrays, especially by nanopillar
arrays with a diameter of 200 nm. Moreover, an in vivo animal model
of the samples demonstrated that PLA film with the 200 nm pillar array
exhibits an improved ectopic osteogenic ability compared with the
planar PLA film after 4 weeks of ectopic implantation. This study
has provided a new variable to investigate in the interaction between
stem cells and nanoarray structures, which will guide the bone regeneration
clinical research field. This work paves the way for the utility of
degradable biopolymer nanoarrays with specific geometrical and mechanical
signals in biomedical applications, such as patches and strips for
spine fusion, bone crack repair, and restoration of tooth enamel
Responses of sequential and hierarchical phenological events to warming and cooling in alpine meadows
Organisms' life cycles consist of hierarchical stages, from a single phenological stage (for example, flowering within a season), to vegetative and reproductive phases, to the total lifespan of the individual. Yet phenological events are typically studied in isolation, limiting our understanding of life history responses to climate change. Here, we reciprocally transfer plant communities along an elevation gradient to investigate plastic changes in the duration of sequential phenological events for six alpine species. We show that prolonged flowering leads to longer reproductive phases and activity periods when plants are moved to warmer locations. In contrast, shorter post-fruiting leaf and flowering stages led to shorter vegetative and reproductive phases, respectively, which resulted in shorter activity periods when plants were moved to cooler conditions. Therefore, phenological responses to warming and cooling do not simply mirror one another in the opposite direction, and low temperature may limit reproductive allocation in the alpine region