An effective strategy is developed for growing Co/N-doped carbon nanotube arrays on 2D MOFs-derived matrix. The constructed architecture can effectively integrate the 0D/1D Co nanoparticle/N-doped ...carbon nanotube interface and 1D (nanotubes)/2D (nanosheets) junction into frameworks with excellent performance towards oxygen reduction reaction in both alkaline and acidic media.
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The development of high-performance and cost-effective electrocatalysts towards oxygen reduction reaction (ORR) is of significant importance, but still challenging for the practical applications in related energy systems. ORR process typically suffers from sluggish kinetics, the exploration of ORR electrocatalyst thus requires elaborate design. Herein, an effective strategy is developed for growing Co/N-doped carbon nanotube arrays on 2D MOFs-derived matrix via the pyrolysis of Co/Zn metal-organic-framework (MOF) nanosheets. The Co/Zn-MOF nanosheets serve as both the self-template for the 2D carbonized framework morphology and C/N source for the in-situ growth of 1D N-doped carbon nanotubes. The constructed hierarchical architecture effectively integrates the 0D/1D Co nanoparticle/N-doped carbon nanotube interface and 1D (nanotubes)/2D (nanosheets) junction into frameworks with highly exposed active surface, enhanced mass-transport kinetics and electrical conductivity. As a result, the designed composite exhibits superior ORR activity and durability in alkaline media as compared to commercial Pt/C. Particularly, it shows promising ORR performance with a half-wave potential of 0.78 V versus reversible hydrogen electrode and negligible activity attenuation after 5000 potential cycles in acidic electrolyte. The designed strategy can be extended to construct other MOFs-derived carbon matrixes with diverse hierarchical structures and provide an efficient avenue for searching high-performance electrocatalysts.
Drought is a major threat to crop productivity and causes decreased plant growth, poor yields, and crop failure. Nevertheless, the frequency of droughts is expected to increase in the coming decades. ...The microbial communities associated with crop plants can influence how plants respond to various stresses; hence, microbiome manipulation is fast becoming an effective strategy for improving the stress tolerance of plants. The effect of drought stress on the root microbiome of perennial woody plants is currently poorly understood. Using
Populus
trees as a model ecosystem, we found that the diversity of the root microbial community decreased during drought treatment and that compositional shifts in microbes during drought stress were driven by the relative abundances of a large number of dominant phyla, including Actinobacteria, Firmicutes, and Proteobacteria. A subset of microbes, including
Streptomyces rochei
,
Bacillus arbutinivorans
,
B. endophyticus
,
B. megaterium
,
Aspergillus terreus
,
Penicillium raperi
,
Trichoderma ghanense
,
Gongronella butleri
, and
Rhizopus stolonifer
, was isolated from the drought-treated poplar rhizosphere soils, which have potentially beneficial to plant fitness. Further controlled inoculation experiments showed that the isolated bacterial and fungal isolates positively impacted plant growth and drought tolerance. Collectively, our results demonstrate the impact of drought on root microbiome structure and provide a novel example of manipulating root microbiomes to improve plant tolerance.
Transparent YAG ceramics were fabricated by solid state reaction sintering using divalent dopants (CaO and MgO) as sintering additives without TEOS doping, and the effects of divalent dopants on ...their microstructure evolution and optical properties were investigated. It was found that CaO was more effective with respect to inhibiting grain growth than MgO, but not as effective as MgO in promoting densification. Fully dense, transparent YAG ceramics with excellent optical qualities could be achieved by optimizing the doping concentrations of CaO and MgO; the transmittance at 1064nm was as high as 84.5% for 3mm thick sample at the molar ratio of Ca: Mg=1:4, after sintered at 1840°C for 8h in vacuum.
MicroRNAs (miRNAs) contribute to plant defense responses by increasing the overall genetic diversity; however, their origins and functional importance in plant defense remain unclear. Here, we ...employed Illumina sequencing technology to assess how miRNA and messenger RNA (mRNA) populations vary in the Chinese white poplar (
Populus tomentosa
) during a leaf black spot fungus (
Marssonina brunnea
) infection. We sampled RNAs from infective leaves at conidia germinated stage 12 h post-inoculation (hpi), infective vesicles stage (24 hpi), and intercellular infective hyphae stage (48 hpi), three essential stages associated with plant colonization and biotrophic growth in
M. brunnea
fungi. In total, 8,938 conserved miRNA-target gene pairs and 3,901
Populus
-specific miRNA-target gene pairs were detected. The result showed that
Populus-
specific miRNAs (66%) were more involved in the regulation of the disease resistance genes. By contrast, conserved miRNAs (>80%) target more whole-genome duplication (WGD)-derived transcription factors (TFs). Among the 1,023 WGD-derived TF pairs, 44.9% TF pairs had only one paralog being targeted by a miRNA that could be due to either gain or loss of a miRNA binding site after the WGD. A conserved hierarchical regulatory network combining promoter analyses and hierarchical clustering approach uncovered a miR164–NAM, ATAF, and CUC (NAC) transcription factor–mRNA regulatory module that has potential in
Marssonina
defense responses. Furthermore, analyses of the locations of miRNA precursor sequences reveal that pseudogenes and transposon contributed a certain proportion (∼30%) of the miRNA origin. Together, these observations provide evolutionary insights into the origin and potential roles of miRNAs in plant defense and functional innovation.
Transposable elements (TEs) are a class of mobile genetic elements that make effects on shaping rapid phenotypic traits of adaptive significance. TE insertions are usually related to transcription ...changes of nearby genes, and thus may be subjected to purifying selection. Based on the available genome resources of
, we found that the composition of Helitron DNA family were highly variable and could directly influence the transcription of nearby gene expression, which are involving in stress-responsive, programmed cell death, and apoptosis pathway. Next, we indicated TEs are highly enriched in
compared with three other congeneric poplar species, especially located at untranslated regions (3'UTRs and 5'UTRs) and Helitron transposons, particularly 24-nt siRNA-targeted, are significantly associated with reduced gene expression. Additionally, we scanned a representative resequenced
population, and identified 9,680 polymorphic TEs loci. More importantly, we identified a Helitron transposon located at the 3'UTR, which could reduce
expression level. Our results highlight the importance of TE insertion events, which could regulate gene expression and drive adaptive phenotypic variation in
.
Abstract
Highly stable pulsed fiber lasers are key optical components in optical communication, optical sensing, and precision micromachining systems due to the high beam quality, high peak power, ...and compact configurations. However, the available optical modulators in the fiber laser suffer from the operation bandwidth limitations and poor long-term physicochemical stability. Here, we have investigated the broadband nonlinear optical absorption behavior of the chromium iodide (CrI
3
) film, which exhibits broadband saturable absorption towards the mid-infrared regime and excellent long-term stability. The conventional soliton fiber laser operating at telecom wavelength has been obtained from an Er
3+
-doped fiber laser (EDFL) utilizing CrI
3
film with a signal-to-noise ratio (SNR) of 92.4 dB and a pulse width of 492 fs. In addition, a passively Q-switched operation around 2.8 μm has also been obtained from an Er
3+
-doped ZBLAN fiber laser (EDZFL) modulated by the CrI
3
film with a SNR of 46.8 dB and a pulse width of 766 ns. The demonstration shows that the CrI
3
film exhibits robust broadband optical modulation, and may make inroads for developing highly stable ultrafast optoelectronic devices.
Mobile health (mHealth) apps are rapidly emerging technologies in China due to strictly controlled medical needs during the COVID-19 pandemic while continuing essential services for chronic diseases. ...However, there have been no large-scale, systematic efforts to evaluate relevant apps.
We aim to provide a landscape of mHealth apps in China by describing and comparing digital health concerns before and after the COVID-19 outbreak, including mHealth app data flow and user experience, and analyze the impact of COVID-19 on mHealth apps.
We conducted a semilongitudinal survey of 1593 mHealth apps to study the app data flow and clarify usage changes and influencing factors. We selected mHealth apps in app markets, web pages from the Baidu search engine, the 2018 top 100 hospitals with internet hospitals, and online shopping sites with apps that connect to smart devices. For user experience, we recruited residents from a community in southeastern China from October 2019 to November 2019 (before the outbreak) and from June 2020 to August 2020 (after the outbreak) comparing the attention of the population to apps. We also examined associations between app characteristics, functions, and outcomes at specific quantiles of distribution in download changes using quantile regression models.
Rehabilitation medical support was the top-ranked functionality, with a median 1.44 million downloads per app prepandemic and a median 2.74 million downloads per app postpandemic. Among the top 10 functions postpandemic, 4 were related to maternal and child health: pregnancy preparation (ranked second; fold change 4.13), women's health (ranked fifth; fold change 5.16), pregnancy (ranked sixth; fold change 5.78), and parenting (ranked tenth; fold change 4.03). Quantile regression models showed that rehabilitation (P
, P
), pregnancy preparation (P
), bodybuilding (P
, P
), and vaccination (P
) were positively associated with an increase in downloads after the outbreak. In the user experience survey, the attention given to health information (prepandemic: 249/375, 66.4%; postpandemic: 146/178, 82.0%; P=.006) steadily increased after the outbreak.
mHealth apps are an effective health care approach gaining in popularity among the Chinese population following the COVID-19 outbreak. This research provides direction for subsequent mHealth app development and promotion in the postepidemic era, supporting medical model reformation in China as a reference, which may provide new avenues for designing and evaluating indirect public health interventions such as health education and health promotion.
We investigate immigration issues in terms of the prisoner’s dilemma game with population change on a dynamic network. We propose a relationship updating phase considering individuals’ irrational ...behavior to demonstrate the dynamics of the game relationship network. Compared with the static network, immigration effectiveness on the dynamic network is significantly improved. By analyzing the influence of immigration volume, it is found that too many immigrants into society together would reduce the immigration effectiveness. However, batch-based immigration can make it insensitive to the volume at the cost of lengthening the time it takes for society to reach equilibrium again after immigration. Detailed simulations reveal that the cooperation level of immigrants can hardly threaten the survival of natives but is the key to immigrants, while the immigrants with abundant relationships do. Besides, the immigration effectiveness is also determined by the temptation to defect, the minimum requirements in society, the death probability, the probability of relationship updating mode and the game experience in terms of regression analysis. In addition, the stability of dynamic society towards immigration events has been demonstrated by analysis of variance.
Hepcidin deficiency is known to cause body iron accumulation and bone microarchitecture defects, but the exact underlying mechanisms of hepcidin deficiency-induced bone loss remain unclear. Our ...objective was to understand the molecular mechanism of hepcidin deficiency-induced bone loss.
The bone phenotypes of wild type (WT) and hepcidin knockout (Hepcidin-KO) mice were measured by microcomputed tomography. The osteoclastic marker of the bone was measured by tartrate-resistant acid phosphatase staining. The osteoblastic marker of the bone was measured by immunostaining of osteocalcin. Primary osteoblastic and osteoclastic differentiation was performed using bone marrow cells. The mature osteoclast was determined by tartrate-resistant acid phosphatase staining, pit formation assay and relative gene expression. The mature osteoblast was determined by alkaline phosphatase activity, alkaline phosphatase staining, Alizarin Red staining and relative gene expression. The protein expression of β-catenin, TCF4/TCF7L2 and Forkhead box O3a (FOXO3a) was measured by Western blot and their combination by co-immunoprecipitation. In vivo study was performed by tail vein administration of FOXO3a-RNAi using an adeno-associated virus in Hepcidin-KO mice.
We found that Hepcidin-KO mice exhibited iron accumulation and bone loss compared with WT mice. The osteoclastic differentiation of bone marrow-derived macrophages from Hepcidin-KO mice was not significantly different from that of bone marrow–derived macrophages from WT mice. However, the osteoblastic differentiation of bone marrow–derived mesenchymal stem cells from Hepcidin-KO mice was obviously decreased compared with that of bone marrow–derived mesenchymal stem cells from WT mice. Furthermore, it was confirmed in this study that upon hepcidin deficiency, β-catenin, TCF4/TCF7L2 and FOXO3a expression in bone tissues was not altered, but β-catenin combination with TCF4/TCF7L2 was strongly inhibited by β-catenin combination with FOXO3a, indicating that the canonical Wnt/β-catenin pathway was affected. Tail vein administration of FOXO3a-RNAi using an adeno-associated virus in Hepcidin-KO mice resulted in bone mass recovery.
These findings suggested that hepcidin deficiency might cause bone loss by interfering with the canonical Wnt/β-catenin pathway via FOXO3a, and FOXO3a inhibition would be a possible approach to treat hepcidin deficiency-induced bone loss.
Hepcidin deficiency, as well as iron accumulation, has been considered as a risk factor for osteoporosis. For this kind of osteoporosis, inhibition of FOXO3a either by neutralized antibody or AAV-mediated RNAi, represents an effective and promising method.
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