Mesenchymal stem cell (MSC)-derived exosomes have been recognized as new candidate agents for treating critical-sized bone defects; they promote angiogenesis and may be an alternative to cell ...therapy. In this study, we evaluated whether exosomes derived from bone marrow-derived MSCs (BMSCs) preconditioned with a low dose of dimethyloxaloylglycine (DMOG), DMOG-MSC-Exos, exert superior proangiogenic activity in bone regeneration and the underlying mechanisms involved.
To investigate the effects of these exosomes, scratch wound healing, cell proliferation, and tube formation assays were performed in human umbilical vein endothelial cells (HUVECs). To test the effects in vivo, a critical-sized calvarial defect rat model was established. Eight weeks after the procedure, histological/histomorphometrical analysis was performed to measure bone regeneration, and micro-computerized tomography was used to measure bone regeneration and neovascularization.
DMOG-MSC-Exos activated the AKT/mTOR pathway to stimulate angiogenesis in HUVECs. This contributed to bone regeneration and angiogenesis in the critical-sized calvarial defect rat model in vivo.
Low doses of DMOG trigger exosomes to exert enhanced proangiogenic activity in cell-free therapeutic applications.
Formaldehyde (FA), the smallest molecular aldehyde with strong reducing properties, could regulate body homeostasis endogenously during physiological and pathological processes. The effective ...near-infrared (NIR) fluorescent probe is needed as a visualizer of FA in biologic organisms. In this work, a novel NIR fluorescent Probe-NHNH 2 was designed on the basis of Probe-NH 2 via introducing a strong nucleophilic hydrazine group, which can be used as a quenching and recognizing moiety for the detection of FA. With the treatment of FA, the hydrazine group of Probe-NHNH 2 undergoes condensation and achieves a turn-on NIR fluorescence signal at a wavelength of 706 nm. The spectroscopic performance of Probe-NHNH 2 for FA was evaluated, and it exhibited high sensitivity and selectivity for the detection of FA in solution. Moreover, compared to the amine moiety-based Probe-NH 2, which our group reported, we found that hydrazine moiety-based Probe-NHNH 2 , exhibited a better reaction time of within 10 min and a lower detection limit of 0.68 μM, reflecting that the reaction of FA with hydrazine moiety is faster and more sensitive than that of FA with the amino group. More importantly, Probe-NHNH 2 was successfully applied to real-time imaging of endogenous FA by reacting with effective stimulant tetrahydrofolate and scavenger sodium bisulfite in zebrafish and mice. It is expected that we can provide a new rapid, sensitive NIR fluorescence theoretical basis for FA detection and in vivo imaging applications.
Mass wasting features have long been noticed on the Moon, but there has been no systematic studies for their morphological, geometrical, or distribution characteristics. The effect of mass wasting on ...topographic evolution and surface erosion on the Moon is not fully understood. Using high-resolution image and topography data obtained from the Lunar Reconnaissance Orbiter spacecraft, we found that mass wasting has been globally and continuously occurring on the Moon. Meteor impacts and moonquakes are the two major triggering mechanisms in forming lunar mass wasting features. We selected over 300 examples of lunar mass wasting features and classified them as falls, flows, slides, slumps, and creeps after studying their morphology, potential mode of emplacement, and sizes of displaced materials. The slope and age distributions for their host terrains are studied to estimate the topographic evolutionary sequence of the lunar surface under the effect of mass wasting. Due to continuous reshaping by mass wasting, surface topographies on the Moon tend to become smoother with time, with fewer mass wasting events occurring on older surfaces. Pre-Nectarian surfaces may represent the final stage of surface topographic evolution on slope angles regarding the effect of mass wasting. Crater densities on lunar surfaces vary with slope angles because the surface erosion rate and regolith production rate on slopes are larger than those on flat areas.
•LROC NAC images reveal that various mass wasting features globally occur on the Moon.•Slopes with smaller ages and steeper slopes generally host more mass wasting features.•Lunar surface is geologically activity due to continuous reshaping by mass wasting.•Surface erosion and regolith production rates are larger on slope due to mass wasting.•Pre-Nectarian surfaces represent the final evolutionary stage of mass wasting.
Cardiovascular disease is a primary cause of death in patients with chronic obstructive pulmonary disease (COPD). Beta-blockers have been proved to reduce morbidity and improve survival in patients ...with cardiac diseases. But the effects of beta-blockers on outcomes in patients with COPD remain controversial. The objective of this meta-analysis was to assess the effect of beta-blockers on mortality and exacerbation in patients with COPD.
An extensive search of the EMBASE, MEDLINE and Cochrane was performed to retrieve the studies of beta-blockers treatment in patients with COPD. The random effects model meta-analysis was used to evaluate effect on overall mortality and exacerbation of COPD.
Fifteen original observational cohort studies with a follow-up time from 1 to 7.2 years were included. The results revealed that beta-blockers treatment significantly decreased the risk of overall mortality and exacerbation of COPD. The relative risk (RR) for overall mortality was 0.72 (0.63 to 0.83), and for exacerbation of COPD was 0.63 (0.57 to 0.71). In subgroup analysis of COPD patients with coronary heart disease or heart failure, the risk for overall mortality was 0.64 (0.54-0.76) and 0.74 (0.58-0.93), respectively.
The findings of this meta-analysis confirmed that beta-blocker use in patients with COPD may not only decrease the risk of overall mortality but also reduce the risk of exacerbation of COPD. Beta-blocker prescription for cardiovascular diseases needs to improve in COPD patients.
Au nanorods (NRs) decorated carbon nitride nanotubes (Au NRs/CNNTs) photocatalysts have been designed and prepared by impregnation–annealing approach. Localized surface plasmon resonance (LSPR) peaks ...of Au NRs can be adjusted by changing the aspect ratios, and the light absorption range of Au NRs/CNNTs is extended to longer wavelength even near‐infrared light. Optimal composition of Pt@Au NR769/CNNT650 has been achieved by adjusting the LSPR peaks of Au NRs and further depositing Pt nanoparticles (NPs), and the photocatalytic H2 evolution rate is 207.0 µmol h−1 (20 mg catalyst). Preliminary LSPR enhancement photocatalytic mechanism is suggested. On one hand, LSPR of Au NRs is beneficial for visible‐light utilization. On the other hand, Pt NPs and Au NRs have a synergetic enhancement effect on photocatalytic H2 evolution of CNNTs, in which the local electromagnetic field can improve the photogenerated carrier separation and direct electron transfer increases the hot electron concentration while Au NRs as the electron channel can well restrain charge recombination, finally Pt as co‐catalyst can boost H+ reduction rate. This work provides a new way to develop efficient photocatalysts for splitting water, which can simultaneously extend light absorption range and facilitate carrier generation, transportation and reduce carrier recombination.
Plasmonic photocatalysts: Au nanorods (Au NRs) can improve the photocatalytic activity of carbon nitride nanotubes (CNNTs), because the localized surface plasmon resonance (LSPR) of Au NRs can improve the carrier separation/migration and extend light absorption. After loading Pt, the synergetic effect from LSPR of Au NRs and co‐catalyst of Pt can boost H2 evolution of CNNTs.
Forest change monitoring is a fundamental and routine task for forest survey and planning departments, and the resulting forest change information acts as an underlying asset for sustainable forest ...management strategy development, ecological quality assessment, and carbon cycle research. The traditional ground-based manual monitoring of forest change has the disadvantages of high time and labor costs, low accessibility, and poor timeliness over wide regions. Remote sensing technology has become a popular approach for multi-scale forest change monitoring due to its multiple available spatial, spectral, temporal, and radiometric resolutions and wide coverage. Particularly, the free access policy of long time series archive data of Landsat (around 50 years) has triggered many automated analysis algorithms for landscape-scale forest change analysis, such as VCT, LandTrendr, BFAST, and CCDC. These automated algorithms differ in their principles, parameter settings, execution complexity, and disturbance types to be detected. Thus, selecting a suitable algorithm to satisfy the particular forest management demands is an urgent and challenging task for forest managers in a given forested area. In this study, Lishui City, Zhejiang Province, a typical plantation forest region in Southern China where forest disturbance widely and frequently exists, was selected as the study area. Based on the GEE platform, the algorithmic adaptability of VCT, LandTrendr, and CCDC in monitoring abrupt forest disturbance events was compared and assessed. The results showed that the kappa coefficients of the abrupt disturbance events detected by the three algorithms were at 0.704 (LandTrendr), 0.660 (VCT), and 0.727 (CCDC), and the corresponding overall accuracies were at 0.852, 0.830, and 0.862, respectively. The validated disturbance occurrence time consistency reached nearly 80% for the three algorithms. In light of the characteristics of forest disturbance occurrence in southeastern China as well as the algorithmic complexity, efficiency, and adaptability, LandTrendr was recommended as the most suitable one in this region or other similar regions. Overall, the forest change monitoring process based on GEE is becoming more simplified and easily implemented, and the comparisons and tradeoffs in this study provide a reference for the choice of long time series forest monitoring algorithms.
Aluminum production is a major energy consumer and source of greenhouse gas (GHG) emissions. The regional transfer of the primary aluminum (PA) industry, which mainly consists of the processes of ...electrolysis and aluminum ingot casting, is currently an important international trend in aluminum industrial development. However, the changes in GHG emissions from aluminum production for such transfers are unclear. This study has established a life cycle assessment model of aluminum industry based on regional transfers in the context of China, determined the GHG emissions of PA and secondary aluminum (SA) production, examined the GHG emission changes of PA production based on regional industry transfer between the years 2007 and 2017, and explored seven driving factors that affect GHG emissions in the aluminum industry. GHG emissions per unit PA and SA production in China decreased by 18.6% and 6.3%, respectively, but the total GHG emissions from aluminum industry still increased by 2.2 times between the years 2007 and 2017. The driving factor analysis showed that the major positive effects of GHG emissions from China's aluminum industry from 2007 to 2017 included the production scale effect of SA and the energy structure effect. Existing regional transfers (between the years 2007 and 2017) did not deliver significant annual GHG emissions reductions. Currently, Xinjiang, Henan, Shandong, and Inner Mongolia are the main PA production provinces in China, although regional transfers have been implemented. This study provides a basis for the improvement and sustainable development of the aluminum industry, suggests policies for regional aluminum development, and proposes a beneficial layout of the aluminum industry.
In plants, microRNAs (miRNAs) associate with ARGONAUTE (AGO) proteins and act as sequence-specific repressors of target gene expression, at the post-transcriptional level through target transcript ...cleavage and/or translational inhibition. MiRNAs are mainly transcribed by DNA-dependent RNA polymerase II (POL II) and processed by DICER LIKE1 (DCL1) complex into 21∼22 nucleotide (nt) long. Although the main molecular framework of miRNA biogenesis and modes of action have been established, there are still new requirements continually emerging in the recent years. The studies on the involvement factors in miRNA biogenesis indicate that miRNA biogenesis is not accomplished separately step by step, but is closely linked and dynamically regulated with each other. In this article, we will summarize the current knowledge on miRNA biogenesis, including
gene transcription, primary miRNA (pri-miRNA) processing, miRNA AGO1 loading and nuclear export; and miRNA metabolism including methylation, uridylation and turnover. We will describe how miRNAs are produced and how the different steps are regulated. We hope to raise awareness that the linkage between different steps and the subcellular regulation are becoming important for the understanding of plant miRNA biogenesis and modes of action.
Objectives
To investigate the use of reverse attenuation gradient sign (RAGS) in CT angiography (CTA) to differentiate total from subtotal occlusion in lower extremities which poses different ...challenges for the procedure and carries different prognoses.
Methods
Eighty patients with 91 lesions in the lower extremities were divided into total occlusion (TO) group and subtotal occlusion (SO) group confirmed by digital subtraction angiography. The CT numbers of vascular lumen at the end of lesion (proximal, P) and at the first entrance (distal, D) of the lateral branch were measured and their difference (CT(PD) = CT(P) − CT(D)) of each lesion was calculated. The CT number gradient (G(DP) = 2 * CT(PD)/CT(P) + CT(D)) was calculated by dividing the CT number difference by the average CT number of the two points. The existence of RAGS where the CT number at the distal point is higher than that at the proximal point (CT(PD) and G(PD) < 0) was determined and the diagnostic efficacy of using RAGS in CTA for differentiating total from subtotal occlusive lesions in lower extremities was calculated.
Results
The SO group had higher CT numbers than the TO group (
p
< 0.001). More importantly, the SO group had positive CT number gradient (G(PD) > 0), while the gradient was negative (G(PD) < 0) in the TO group. The specificity and sensitivity of using RAGS (G(PD) < 0) in images for diagnosing TO of lower extremity were 97.6% and 92.0%, respectively, and 87.8% and 88.0% using the standard CTA images.
Conclusion
The use of RAGS in CTA images has high diagnostic accuracy to differentiate TO from SO in lower extremities.
Key Points
• Total occlusions often exhibit higher CT number at distal point than at proximal point to the occlusion.
• The reverse attenuation gradient sign (RAGS) may be determined using the CT number measurements between the proximal and distal points after occlusion.
• RAGS can be used to improve the diagnostic efficiency in CTA to differentiate between total and subtotal occlusions of lower extremity arteries.
•Two different kinds of PDMS films were prepared by spin-coated.•The PDMS surface was plasma treated with different power and time.•The output performance of TENG was significantly enhanced by plasma ...treatment.•Plasma treatment effect has time-efficient, the output declines with store time.
Physical and chemical properties of the polymer surface play great roles in the output performance of triboelectric nanogenerator (TENG). Specific texture on the surface of polymer can enlarge the contact area and enhance the power output performance of TENG. In this paper, polydimethylsiloxane (PDMS) films with smooth and micro pillar arrays on the surface were prepared respectively. The surfaces were treated by argon plasma before testing their output performance. By changing treatment parameters such as treating time and plasma power, surfaces with different roughness and their relationship were achieved. The electrical output performances of the assembled TENG for each specimen showed that argon plasma treatment has a significant etching effect on the PDMS surface and greatly strengthen its output performance. The average surface roughness of PDMS film increases with the etching time from 5mins to 15 mins when the argon plasma power is 60W. Nevertheless, the average surface roughness is inversely proportional to the treatment time for the power of 90W. When treated with 90W and 5mins, many uniform micro pillars appeared on the both PDMS surface, and the output performance of the TENG for plasma treated smooth surface is 2.6 times larger than that before treatment. The output voltage increases from 42V to 72V, and the short circuit current increases from 4.2μA to 8.3μA after plasma treatment of the micro pillar array surface. However, this plasma treatment has time-efficient due to the hydrophobic recovery property of Ar plasma treated PDMS surface, both output voltage and short circuit current decrease significantly after 3 months.
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