Degradation: A critical challenge for M–N–C electrocatalysts

Author(s):  
Yongchao Yang ◽  
Leo Lai ◽  
Li Wei ◽  
Yuan Chen
Keyword(s):  
2016 ◽  
Vol 64 (2) ◽  

Strategies to improve cognitive aging are highly needed. Among those, promotion of exercise and physical activity appears as one of the most attractive and beneficial intervention. Indeed, results from basic and clinical studies suggest that exercise and physical activity have positive effects on cognition in older persons without cognitive impairment, as well as in those with dementia. Despite inconsistent results, aerobic exercise appears to have the strongest potential to enhance cognition. However, even limited periods of walking (45 minutes, three times a week, over a 6-month period) have also been shown to enhance cognition, particularly executive functions. Changing long-term lifestyle habits in these older persons remains a critical challenge and attractive programs susceptible to gain adherence are needed to succeed in achieving improved cognitive aging.


2015 ◽  
Vol 3 (7) ◽  
Author(s):  
Patrick Bond

<p class="p1"><span class="s2"><strong>Abstract </strong></span>| The challenge of interdisciplinary intellectual and strategic work in the extractive industries is particularly acute at the interface of research and social activism. Numerous social movements which are dedicated to sustainability fail to ‘connect the dots’ between their campaigns and broader political-economic and political-ecological visions<span class="s3"><strong>. </strong></span>This is becoming a critical challenge in Africa, where the extreme damage done by mining and fossil fuels has generated impressive resistance<span class="s3"><strong>.</strong></span>However, the one obvious place to link these critiques from African activists was the Alternative Mining Indaba in Cape Town in February 2015, and a survey of narratives at that event leads to pessimism about interdisciplinary politics. The potential for much greater impact and deeper critiques of unsustainable extractivism lies in greater attention to combining social reproduction and production (as do eco-feminists), and to tackling social, economic, political and ecological factors with a more explicit structuralist critique and practical toolkit<span class="s3"><strong>. </strong></span>Areas such as energy, economics and climate are ripe for linkages<span class="s3"><strong>. </strong></span>One reason for optimism is a climate justice declaration made by leading civil society activists in Maputo in April 2015.<strong></strong></p>


Author(s):  
Mukul Sharma

Rarely do Indian environmental discourses examine nature through the lens of caste. Whereas nature is considered as universal and inherent, caste is understood as a constructed historical and social entity. Mukul Sharma shows how caste and nature are intimately connected. He compares Dalit meanings of environment to ideas and practices of neo-Brahmanism and certain mainstreams of environmental thought. Showing how Dalit experiences of environment are ridden with metaphors of pollution, impurity, and dirt, the author is able to bring forth new dimensions on both environment and Dalits, without valourizing the latter’s standpoint. Rather than looking for a coherent understanding of their ecology, the book explores the diverse and rich intellectual resources of Dalits, such as movements, songs, myths, memories, and metaphors around nature. These reveal their quest to define themselves in caste-ridden nature and building a form of environmentalism free from the burdens of caste. The Dalits also pose a critical challenge to Indian environmentalism, which has, until now, marginalized such linkages between caste and nature.


2021 ◽  
Author(s):  
Chengqiang Wang ◽  
Haixia Xu ◽  
Chun Liu ◽  
Ziyue Peng ◽  
Ruoxing Min ◽  
...  

Osteonecrosis of femoral head (ONFH), a common refractory disease, is not fully understood today. Hypoxia caused by ischemia is not only an important pathogenic factor, but also a critical challenge...


Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 208
Author(s):  
Qifei Zhou ◽  
Changqing Zhu ◽  
Na Ren ◽  
Weitong Chen ◽  
Weiteng Gong

Zero watermarking is an important part of copyright protection of vector geographic data. However, how to improve the robustness of zero watermarking is still a critical challenge, especially in resisting attacks with significant distortion. We proposed a zero watermarking method for vector geographic data based on the number of neighboring features. The method makes full use of spatial characteristics of vector geographic data, including topological characteristics and statistical characteristics. First, the number of first-order neighboring features (NFNF) and the number of second-order neighboring features (NSNF) of every feature in vector geographic data are counted. Then, the watermark bit is determined by the NFNF value, and the watermark index is determined by the NSNF value. Finally, combine the watermark bits and the watermark indices to construct a watermark. Experiments verify the theoretical achievements and good robustness of this method. Simulation results also demonstrate that the normalized coefficient of the method is always kept at 1.00 under the attacks that distort data significantly, which has the superior performance in comparison to other methods.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Chenya Zhuo ◽  
Jiabin Zhang ◽  
Jung-Hwan Lee ◽  
Ju Jiao ◽  
Du Cheng ◽  
...  

AbstractThe clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) gene editing technology, as a revolutionary breakthrough in genetic engineering, offers a promising platform to improve the treatment of various genetic and infectious diseases because of its simple design and powerful ability to edit different loci simultaneously. However, failure to conduct precise gene editing in specific tissues or cells within a certain time may result in undesirable consequences, such as serious off-target effects, representing a critical challenge for the clinical translation of the technology. Recently, some emerging strategies using genetic regulation, chemical and physical strategies to regulate the activity of CRISPR/Cas9 have shown promising results in the improvement of spatiotemporal controllability. Herein, in this review, we first summarize the latest progress of these advanced strategies involving cell-specific promoters, small-molecule activation and inhibition, bioresponsive delivery carriers, and optical/thermal/ultrasonic/magnetic activation. Next, we highlight the advantages and disadvantages of various strategies and discuss their obstacles and limitations in clinical translation. Finally, we propose viewpoints on directions that can be explored to further improve the spatiotemporal operability of CRISPR/Cas9.


2017 ◽  
Vol 9 (402) ◽  
pp. eaaf9547 ◽  
Author(s):  
Tim K. Mackey ◽  
Jillian Kohler ◽  
Maureen Lewis ◽  
Taryn Vian

Corruption is a critical challenge to global health efforts, and combating it requires international action, advocacy, and research.


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