Because of high sensitivity, mechanical robustness, lightweight and wearability, flexible capacitive pressure transducer has been widely considered one of the most critical soft electronics in ...wearable consumables and e-skins. The enhancement of the pressure sensitivity of a flexible capacitive sensor relies on the introduction of interfacial microstructure to the dielectric layer. We demonstrate a new methodology to fabricate flexible capacitive sensors with copper-plated polyimide (PI) films as the electrodes and a porous polydimethylsiloxane (PDMS) layer 3D printed via the direct-ink-writing approach. Time-of-flight secondary ion mass spectrometry is developed to optimize the electroless copper plated PI films. What is further examined is the impact of the geometric complexity of the cellular PDMS structure, including filament width, spacing and alignment, on sensitivity, repeatability and reliability of the developed capacitive sensor. A robotic gripper equipped with our flexible pressure sensor showcases its competence to grip a soft target with well-posed force control. It is expected that our proposed sensor design and manufacturing methodology will advance the development of soft electronics and wearable sensors.
The Himalaya, the world's highest mountain ranges, are home to a large group of glaciers and glacial lakes. Glacial lake outburst floods (GLOFs) in this region have resulted in catastrophic damages ...and fatalities in the past decades. The recent warming has caused dramatic glacial lake changes and increased potential GLOF risk in the Himalaya. However, our knowledge on the current state and change of glacial lakes in the entire Himalaya is limited. This study maps the current (2015) distribution of glacial lakes across the entire Himalaya and monitors the spatially-explicit evolution of glacial lakes over five time periods from 1990 to 2015 using a total of 348 Landsat images at 30m resolution. The results show that 4950 glacial lakes in 2015 cover a total area of 455.3±72.7km2, mainly located between 4000m and 5700m above sea level. Himalayan glacial lakes expanded by approximately 14.1% from 1990 to 2015. The changing patterns of supraglacial lakes and proglacial lakes are rather complex, involving both lake disappearance and emergence. Many emergent glacial lakes are found at higher elevations, especially the new proglacial lakes, which have formed as a result of glacier retreat. Spatially heterogeneous changes of Himalayan glacial lakes are observed, with the most significant expansion occurring in the southern slopes of the central Himalaya. Increasing glacier meltwater induced by the Himalayan atmospheric warming is a primary cause for the observed lake expansion. This study provides primary data for future GLOF risk assessments. A total of 118 rapidly expanded glacial lakes are identified as potential vulnerable lakes for the priority of risk assessment.
•Revealing the distribution of Himalayan glacial lakes using Landsat 8 images in 2015•Demonstrating the evolution and regional heterogeneity of Himalayan glacial lakes•Detecting the rapidly expanding glacial lakes with potential outburst risk
Glacial lake outburst flood (GLOF) is a serious hazard in high, mountainous regions. In the Himalayas, catastrophic risks of GLOFs have increased in recent years because most Himalayan glaciers have ...experienced remarkable downwasting under a warming climate. However, current knowledge about the distribution and recent changes in glacial lakes within the central Himalaya mountain range is still limited. Here, we conducted a systematic investigation of the glacial lakes within the entire central Himalaya range by using an object-oriented image processing method based on the Landsat Thematic Mapper (TM) or Enhanced Thematic Mapper (ETM) images from 1990 to 2010. We extracted the lake boundaries for four time points (1990, 2000, 2005 and 2010) and used a time series inspection method combined with a consistent spatial resolution of Landsat images that consistently revealed lake expansion. Our results show that the glacial lakes expanded rapidly by 17.11% from 1990 to 2010. The pre-existing, larger glacial lakes, rather than the newly formed lakes, contributed most to the areal expansion. The greatest expansions occurred at the altitudinal zones between 4800 m and 5600 m at the north side of the main Himalayan range and between 4500 m and 5600 m at the south side, respectively. Based on the expansion rate, area and type of glacial lakes, we identified 67 rapidly expanding glacial lakes in the central Himalayan region that need to be closely monitored in the future. The warming and increasing amounts of light-absorbing constituents of snow and ice could have accelerated the melting that directly affected the glacial lake expansion. Across the main central Himalayas, glacial lakes at the north side show more remarkable expansion than those at the south side. An effective monitoring and warning system for critical glacial lakes is urgently needed.
Glacial lake outburst floods (GLOFs) are a unique type of natural hazard in the cryosphere that may result in catastrophic fatalities and damages. The Himalayas are known as one of the world's most ...GLOF-vulnerable zones. Effective hazard assessments and risk management require a thorough inventory of historical GLOF events across the Himalayas, which is hitherto absent. Existing studies imply that numerous historical GLOF events are contentious because of discrepant geographic coordinates, names, or outburst time, requiring further verifications. This study reviews and verifies over 60 historical GLOF events across the Himalayas using a comprehensive method that combines literature documentations, archival remote sensing observations, geomorphological analysis, and field investigations. As a result, three unreported GLOF events were discovered from remote sensing images and geomorphological analysis. Eleven suspicious events were identified and suggested to be excluded. The properties of five outburst lakes, i.e., Degaco, Chongbaxia Tsho, Geiqu, Lemthang Tsho, and a lake on Tshojo Glacier, were corrected or updated. A total of 51 GLOF events were verified to be convincing, and these outburst lakes were classified into three categories according to their statuses in the past decades, namely disappeared (12), stable (30), and expanding (9). Statistics of the verified GLOF events show that GLOF tended to occur between April and October in the Himalayas. We suggest that more attention should be paid to rapidly expanding glacial lakes with high possibility of repetitive outbursts. This study also demonstrates the effectiveness of integrating remote sensing and geomorphic interpretations in identifying and verifying GLOF events in remote alpine environments. This inventory of GLOFs with a range of critical attributes (e.g., locations, time, and mechanisms) will benefit the continuous monitoring and prediction of potentially dangerous glacial lakes and contribute to outburst-induced risk assessments and hazard mitigations.
•Developed a comprehensive method to review and verify historical GLOF events•Verified the persuadability for over 60 Himalayan GLOF events•Revealed the statuses of Himalayan outburst lakes in the past decades•Constructed a GLOF inventory with many critical attributes for hazard assessments
•Two dates of glacial lakes (in 1988 and 2013) across the SETP are inventoried.•The spatio-temporal variations of glacial lakes of different types are investigated.•Surface elevation changes of ...glacial lake and glaciers are measured by ICESat and DEM.•The rapid growth of debris-contact glacial lakes is linked to hydrogeomorphic process.
Glacial lakes, as an important component of the cryosphere in the southeastern Tibetan Plateau (SETP) in response to climate change, pose significant threats to the downstream lives and properties of people, engineering construction, and ecological environment via outburst floods, yet we currently have limited knowledge of their distribution, evolution, and the driving mechanism of rapid expansions due to the low accessibility and harsh natural conditions. By integrating optical imagery, satellite altimetry and digital elevation model (DEM), this study presents a regional-scale investigation of glacial lake dynamics across two river basins of the SETP during 1988–2013andfurther explores the glacial-hydrogeomorphic process of rapidly expanding lakes. In total 1278and1396 glacial lakes were inventoried in 1988and2013, respectively. Approximately 92.4% of the lakes in 2013 are not in contact with modern glaciers, and the remaining 7.6% includes 27 (1.9%) debris-contact lakes (in contact with debris-covered ice) and 80 (5.7%) cirque lakes. In categorizing lake variations, we found that debris-contact proglacial lakes experienced much more rapid expansions (∼75%) than cirque lakes (∼7%) and non-glacier-contact lakes (∼3%). To explore the cause of rapid expansion for these debris-contact lakes, we further investigated the mass balance of parent glaciers and elevation changes in lake surfaces and debris-covered glacier tongues using time-series Landsat images, ICESat altimetry, and DEM. Results reveal that the upstream expansion of debris-contact proglacial lakes was not directly associated with rising water levels but with a geomorphological alternation of upstream lake basins caused by melting-induced debris subsidence at glacier termini. This suggests that the hydrogeomorphic process of glacier thinning and retreat, in comparison with direct glacial meltwater alone, may have played a dominant role in the recent glacial lake expansion observed across the SETP. Our findings assist in understanding the expansion mechanism of debris-contact proglacial lakes, which facilitates early recognition of potential glacial lake hazards in this region.
•Periodic accelerations of a lake-terminating glacier are linked to rapid frontal retreats.•Proglacial lake-ice interactions can greatly modify the ice flow regime.•Recent terminus acceleration has ...likely induced glacier upstream dynamic thinning.•In contrast, a neighboring land-terminating glacier shows on-going deceleration.
Most lake-terminating glaciers in the Himalaya retreat rapidly due to periodic frontal ice loss at their terminus, but long-term observations are still limited regarding their flow dynamics, which is crucial for understanding the processes of ice mass loss and proglacial lake growth. We present multi-decadal surface velocity dynamics of the Longbasaba Glacier, a rapid retreating lake-terminating glacier in the Chinese Himalaya, using an image feature tracking method applied on optical satellite images between 1989 and 2018. We show that, in companion with rapid retreat (−51.7 m a−1), its lower 5 km tongue experienced high interannual fluctuations in velocity, comprising periodic acceleration and slowdown in 1989-1995 and 2001-2010 and a recent remarkable acceleration since 2012. The temporal variation of longitudinal velocity distribution indicates an upward propagation of the lake-ward acceleration (namely a downglacier inversion of strain from compression to extension). This propagation is coupled to the retreat of the glacier front and occurs along the lowermost 1∼1.5 km lake-adjacent section as the proglacial lake expands. The most recent acceleration of the near-lake section since 2012 has likely facilitated a dynamic thinning on its upper sections, where flow acceleration started two years later in 2014. This pattern contrasts markedly with a nearby decelerating land-terminating glacier, which has experienced a much slower retreat rate (−7.8 m a−1) and the same magnitude of mean thinning rate at its lower part since 2000. Our results confirm the strong influence of the proglacial lake on ice flow dynamics and suggest that lake-ice interactions are important to consider when analyzing, interpreting or modeling dynamics of rapidly retreating lake-terminating glaciers in the Himalayas as well as around the world.
The homeostasis of the gut-brain axis has been shown to exert several effects on physiological and psychological health. The gut hormones released by enteroendocrine cells scattered throughout the ...gastrointestinal tract are important signaling molecules within the gut-brain axis. The interaction between gut microbiota and gut hormones has been greatly appreciated in gut-brain cross-talk. The microbiota plays an essential role in modulating many gut-brain axis-related diseases, ranging from gastrointestinal disorders to psychiatric diseases. Similarly, gut hormones also play pleiotropic and important roles in maintaining health, and are key signals involved in gut-brain axis. More importantly, gut microbiota can affect the release and functions of gut hormones. This review highlights the role of gut microbiota in the gut-brain axis and focuses on how microbiota-related gut hormones modulate various physiological functions. Future studies could target the microbiota-hormones-gut brain axis to develop novel therapeutics for different psychiatric and gastrointestinal disorders, such as obesity, anxiety, and depression.
Glacier mass loss in the Himalayas has far-reaching implications for the alteration of regional hydrologic regimes, an increased risk of glacial lake outburst, downstream water resource abundance, ...and contributions to sea level rise. However, the mass losses of Himalayan glaciers are not well understood towing to the scarcity of observations and the heterogeneous responses of Himalayan glaciers to climate change and local factors (e.g., glacier surge, interacting with proglacial lakes). In particular, there is a lack of understanding on the unique interactions between moraine-dammed glacial lakes and their effects on debris cover on valley glacier termini. In this study, we examined the temporal evolution of 151 large glacial lakes across the Himalayas and then classified these glacial lakes into three categories: proglacial lakes in contact with full or partial debris-covered glaciers (debris-contact lakes), ice cliff-contact lakes, and non-glacier-contact lakes. The results show that debris-contact lakes experienced a dramatic areal increase of 36.5% over the years 2000 to 2014, while the latter two categories of lakes remained generally stable. The majority of lake expansions occurred at the glacier front without marked lake level rises. This suggests that the rapid expansion of these debris-contact lakes can be largely attributed to the thinning of debris-covered ice as caused by the melting of glacial fronts and the subsequent glacial retreat. We reconstructed the height variations of glacier fronts in contact with 57 different proglacial lakes during the years 2000 to 2014. These reconstructed surface elevation changes of debris-covered, lake-contact glacier fronts reveal significant thinning trends with considerable lowering rates that range from 1.0 to 9.7m/y. Our study reveals that a substantial average ice thinning of 3.9m/y occurred at the glacier fronts that are in contact with glacial lakes.
Microbes spontaneously release membrane vesicles (MVs), which play roles in nutrient acquisition and microbial interactions. Iron is indispensable for microbes, but is a difficult nutrient to ...acquire. However, whether MVs are also responsible for efficient iron uptake and therefore involved in microbial interaction remains to be elucidated. Here, we used a Gram-positive strain, Dietzia sp. DQ12-45-1b, to analyze the function of its MVs in heme-iron recycling and sharing between species. We determined the structure and constituent of MVs and showed that DQ12-45-1b releases MVs originating from the mycomembrane. When comparing proteomes of MVs between iron-limiting and iron-rich conditions, we found that under iron-limiting conditions, heme-binding proteins are enriched. Next, we proved that MVs participate in extracellular heme capture and transport, especially in heme recycling from environmental hemoproteins. Finally, we found that the heme carried in MVs is utilized by multiple species, and we further verified that membrane fusion efficiency and species evolutionary distance determine heme delivery. Together, our findings strongly suggest that MVs act as a newly identified pathway for heme recycling, and represent a public good shared between phylogenetically closely related species.
In present work, we have developed a simple but effective template carbonization method for producing hollow carbon materials with high content of nitrogen and oxygen from thiocarbanilide. Among all ...samples, the NPC-1 exhibits high specific surface area (736 m2 g−1) and large pore volume (5.93 cm3 g−1) with high content of heteroatoms (∼11.25 at% nitrogen and ∼5.74 at% oxygen), which is conducive to the improvement of electrochemical performance. Specifically, the high specific capacitance and excellent cycling stability over 5000 cycles of the NPC-1-based electrode are achieved in 1 mol L−1 H2SO4 electrolyte. Additionally, pyrocatechol and rutin as novel redox additives that can easily cause redox-reactions have been incorporated into H2SO4 electrolyte to improve the capacitances. As a result, the NPC-1-R-0.15 and NPC-1-P-0.15 samples deliver high specific capacitances of 120.5 and 368.7 F g−1 at 2 A g−1, respectively, which are much higher than that of the NPC-1 sample (66.2 F g−1) without redox-additives at same current density. Furthermore, the large energy density of 18.9 and 11.9 Wh kg−1 of the NPC-1-based symmetric supercapacitors have been obtained in H2SO4+pyrocatechol and H2SO4+rutin electrolyte, respectively, and both samples also demonstrate excellent cyclic performance for 5000 cycles.
•Thiocarbanilide-derived N/O functionalized hollow carbon material (NPC) was synthesized.•Rutin and pyrocatechol were used as redox additives for improving the capacitance of NPC-1.•NPC-1-based symmetric supercapacitor exhibits prominent electrochemical performance.
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