High Plateau Research Articles

Analytic theory of X-ray wideband multilayer coated diffraction gratings

An analytic theory of X-ray (E∼0.04-4 keV) diffraction from wideband multilayer coated gratings is developed. It is found that the wideband blazed gratings can operate in the single-order regime when only one diffraction wave is effectively excited. The diffraction efficiency achieves the reflectivity of conventional depth-graded multilayer mirrors in a wide spectral range. The physical reasons and the conditions of the single-order regime of wideband multilayer grating operation are discussed. A simple and clear design procedure is developed to suppress undesirable diffraction orders. The way to achieve a high diffraction efficiency plateau of 25% throughout the E = 2-3 keV interval is demonstrated.

Lichens are more tolerant against winter warming stress than vascular and non‐vascular plants: Insights from an alpine field experiment

Abstract Extreme weather events influence carbon cycling and lead to pervasive changes in ecosystem structure and function. Vegetation at high latitudes and in alpine bioclimatic zones can be particularly sensitive to winter warming events, which are short‐lived climatic events where temperatures are unusually high and often include rainfall. With climate change the frequency and severity of winter warming events are increasing. We report here from a field experiment on a lichen‐dominated ridge at a high mountain plateau in central Norway. This is a common vegetation type at high latitudes and altitudes, yet little is known about ecophysiological responses to winter warming events in lichens, and how it may differ from responses in bryophytes and vascular plants. We ran a week‐long simulation of vegetation stress from winter warming events through thaw–freeze and ice encasement, during late winter in 2021 and 2022. The thaw–freeze treatment had minor effects on summer ecophysiology in lichens (Cladonia mitis, Cetraria islandica and Nephromopsis nivalis), while the species N. nivalis and to a lesser extent, C. mitis had reduced vitality after the ice encasement treatment. Contrastingly, the bryophyte Polytrichum juniperinum, and vascular plant Empetrum nigrum had reduced photosynthetic efficiency and seasonal growth in both thaw–freeze and ice encasement treatments. The ice encasement treatment was overall more lethal and led to reduced NDVI (Normalised Difference Vegetation Index). However, reduction in vitality of vascular and non‐vascular plants was not enough to impact overall ecosystem carbon flux. Synthesis: The lichen's stronger tolerance against thaw–freeze and ice encasement than co‐existing plants oppose the general effects of summer climate warming, where lichens may succumb under greater plant‐growth and warmer soils. This study advocates for the importance of year‐round ecology to understand vegetation change under climate change.

Recent centennial drought on the Tibetan Plateau is outstanding within the past 3500 years

Given growing concerns about global climate change, it is critical to understand both historical and current shifts in the hydroclimate, particularly in regions critically entwined with global circulation. The Tibetan Plateau, the Earth’s largest and highest plateau, is a nexus for global atmospheric processes, significantly influencing East Asian hydroclimate dynamics through the synergy of the Asian Monsoon and the Westerlies. Yet, understanding historical and recent hydroclimate fluctuations and their wide-ranging ecological and societal consequences remains challenging due to short instrumental observations and partly ambiguous proxy reconstructions. Here, we present a precisely-dated 3476-year precipitation reconstruction derived from tree-ring δ18O data on the Tibetan Plateau, representing one of the few multi-millennia-long annually-resolved terrestrial δ18O records to date. Our findings reveal that the 20th century drought extremes are severe within the past three millennia, and likely linked to the weakening of both the Asian Monsoon and Westerlies due to anthropogenic aerosol emissions. Additionally, our analyses identified three distinct stages (110 BC–AD 280, AD 330–770 and AD 950–1300) characterized by shifts toward arid hydroclimate conditions, corresponding to significant social unrest and dynasty collapses, which underscores the potential societal impacts of severe hydroclimatic shifts.

Polyaniline-modified NiCo layered double hydroxide hollow nanocages for aqueous ammonium-ion supercapacitors.

Aqueous ammonium ion supercapacitors have attracted extensive attention from researchers for their environmental friendliness, high safety, and low cost. Unfortunately, compared with other energy storage technologies, the research and development of high-performance ammonium storage electrode materials is lagging, which has seriously hindered its development. Here, we designed and prepared nickel-cobalt layered double hydroxide nanocages (HLDH@P) with a unique hollow structure and polyaniline (PANI) coating, and used them as ammonium ion energy storage hosts. The optimized HLDH@P electrode material exhibits a great specific capacity of up to 1248F g-1 at 1A/g, while a high discharge plateau of 0.6V is observed. The assembled asymmetric supercapacitor (A-HSC) has an energy density of 42 Wh kg-1 and a corresponding power density of 623W kg-1, while also exhibiting excellent cycling stability. In addition, density functional theory (DFT) shows that the abundant nitrogen-containing groups in the composite material effectively increase the adsorption energy of NH4+ ions, and the large number of hydrogen bonds formed thereby greatly improve the electrochemical performance of the composite material. The results of this study fully demonstrate the broad application prospects of surface engineering in designing high-performance ammonium storage electrode materials.

Will Olive Groves have a Future Under Climate Change Conditions in The North Aegean Sub-Region, a Mediterranean Agricultural Ecosystem of Türkiye?

The study is aimed at investigating future changes in sustainability of olive farming by means of climate change, and changes in agricultural climatic suitableness and phenology of olive tree cultivation in the North Aegean sub-region of Türkiye mainly characterised with dry summer subtropical Mediterranean climate. According to projected changes based on RCP8.5 scenario, projected warming reaches an average of 5-6°C increase indicating most negative condition on olive cultivation. According to RCP8.5 scenario annual precipitation projections, present suitable areas of olive groves will decrease in the period of 2049-2073, and almost the entire study area will be in the category of medium suitable. With respect to projected Emberger Bioclimate classification, for RCP 8.5 scenario, there will be a significant increase in dry-sub humid areas in the period of 2049-2073. This increase will cover up the coastal areas in the period of 2074-2098, and even all the study region will be very likely characterised with dry-sub humid and semi-arid Mediterranean bioclimatic types except for some coastal areas. An increase of about 6°C is expected in maximum values of maximum air temperatures during the bud swelling periods in the spring, especially after 2050 under RCP8.5 scenario. This increase in extreme maximum temperatures may cause olive trees to bloom earlier and prolong the growth period. By regarding the high vernalization requirement of main olive variety in the study area, a 6°C temperature increase may significantly decrease olive yields and will force farmers to transition to new varieties with relatively low vernalization requirements. According to both RCP scenarios, there is a possibility of extension of suitable areas for olive cultivation towards low to mid-elevation plateaus and mid-elevation slopes of mountainous areas and high plateaus particularly facing suitable aspects to lower negative effects of projected future warming and dryness.

Rapid radiation of a plant lineage sheds light on the assembly of dry valley biomes.

Southwest China is characterized by high plateaus, large mountain systems, and deeply incised dry valleys formed by major rivers and their tributaries. Despite the considerable attention given to alpine plant radiations in this region, the timing and mode of diversification of the numerous dry valley plant lineages remain unknown. To address this knowledge gap, we investigated the macroevolution of Isodon (Lamiaceae), a lineage commonly distributed in the dry valleys in southwest China and wetter areas of Asia and Africa. We reconstructed a robust phylogeny encompassing nearly 90% of the approximately 140 extant Isodon species using transcriptome and genome-resequencing data. Our results suggest a rapid radiation of Isodon during the Pliocene that coincided with a habit shift from herbs to shrubs and a habitat shift from humid areas to dry valleys. The shrubby growth form likely acted as a preadaptation allowing for the movement of Isodon species into these dry valleys. Ecological analyses highlight drought-related factors as key drivers influencing the niche preferences of different growth forms and species richness of Isodon. The interplay between topography and the development of the East Asian monsoon since the middle Miocene likely contributed to the formation of the dry valley biome in southwest China. This study enhances our understanding of evolutionary dynamics and ecological drivers shaping the distinctive flora of southwest China and reveals the strategies employed by montane plants in response to climate change and dryland expansion, thus facilitating conservation efforts globally.

Phytodiversity of the green dam: case of Djelfa region (Algeria)

Desertification in Algeria essentially concerns the steppes of the arid and semi-arid regions of the high plateau which are subject to recurrent droughts and increasing anthropogenic pressure; this phenomenon results in the reduction of biological potential. Faced with this alarming situation, a project called the green dam was established with the aim of maintaining ecological balance. The work carried out consists of taking stock of the reforestation of the green dam in the Djelfa region and its impact on phytodiversity by qualitative and quantitative analysis, it aims to highlight the richness of the flora in this area.40 phytosociological surveys used a subjective sampling between March to June 2024 with a minimum surface of 100 m2 allowed us to draw up a list of 109 plant species distributed across 21 botanical families, Asteraceae, Fabaceae, and Poaceae as the most dominant families with (27.5%, 13.8% and 12.8%) respectively. Therophytes represented 57.8% of the biological spectrum, this translates into dominance of annual herbaceous plants with a short life cycle better adapted to semi-arid and arid conditions. Mediterranean species constituted 38,5% of the flora, showcasing the ecological significance of the region. Overall, the results reveal a remarkable floristic richness despite local environmental containments which threaten its sustainability, hence protection and development measures are necessary by managers in order to preserve this natural heritage.

Aqueous Alkaline Zinc-Iodine Battery with Two-Electron Transfer.

While many cathode materials have been developed for mild electrolyte-based Zn batteries, the lack of cathode materials hinders the progress of alkaline zinc batteries. Halide iodine, with its copious valence nature and redox possibilities, is considered a promising candidate. However, energetic alkaline iodine redox chemistry is impeded by an alkali-unadapted I2 element cathode and thermodynamically unstable reaction products. Here, we formulated and evaluated an aqueous alkaline Zn-iodine battery with a two-electron transfer employing an organic iodized salt cathode and a Cl--manipulated electrolyte. The single-step redox reaction of the I-/I+ couple resulted in a high discharge plateau of 1.68 V and a capacity of 385 mA h g-1. Our battery reached an energy density of 577 W h kg-1, superior to that of reported counterparts. Theoretical and experimental characterizations determined the redox chemistry between alkaline and iodine. We believe the developed iodine chemistry in alkaline environments can enrich cathode materials for alkaline batteries.

A Multi‐Colored, Structure‐Tolerant Vanadate Cathode for High‐Performance Aqueous Zinc‐Ion Batteries

AbstractVanadium‐based cathode materials for aqueous zinc‐ion batteries (AZIBs) have attracted much attention in large‐scale energy storage devices yet their unsatisfactory cyclic stability and slow diffusion rate of Zn2+ ions during insertion and extraction hinder further commercial applications. Therefore, the development of vanadium‐based cathode materials with stable crystal structures and fast Zn2+ storage remains challenging. Herein, Na2CaV4O12 (NCVO) nanowires are reported as a promising cathode of excellent electrochemical performance in AZIBs, simultaneously rendering high specific capacity (443.2 mAh g−1 at 0.1 A g−1) and high average voltage plateau (0.91 V) with impressive energy density (403.3 Wh kg−1) and power density (1533 W kg−1). As NCVO features a unique open crystal structure with alternately arranged inactive layers ([NaO6] and [CaO8] polyhedra) and active layers ([VO4] tetrahedra), the expansion of the [VO4] tetrahedra during Zn2+ insertion is well balanced by the contraction of the inactive layer, thus enabling remarkable long‐term cycling stability (91.9% and 80% capacity retention after 5000 and 10 000 cycles at 10 A g−1, respectively). With the electrochromic property of the NCVO cathode, the AZIB can further be used for adaptive camouflage under a range of scenarios, shedding light on the future development of high‐performance cathodes for AZIBs.

A Reduced-Order Model of Lithium–Sulfur Battery Discharge

This paper examines the problem of modeling lithium–sulfur (Li-S) battery discharge dynamics. The importance of this problem stems from the attractive specific energy levels achievable by Li-S batteries, which can be particularly appealing for applications such as aviation electrification. Previous research presents different Li-S battery models, including “zero-dimensional” models that neglect diffusion while using the laws of electrochemistry to represent reduction–oxidation (redox) rates. Zero-dimensional models typically succeed in capturing key features of Li-S battery discharge, including the high plateau, low plateau, and dip point visible in the discharge curves of certain Li-S battery chemistries. However, these models’ use of one state variable to represent the mass of each active species tends to furnish high-order models, with many state variables. This increases the computational complexity of model-based estimation and optimal control. The main contribution of this paper is to develop low-order state-space model of Li-S battery discharge. Specifically, the paper starts with a seventh-order zero-dimensional model of Li-S discharge dynamics, analyzes its discharge behavior, constructs phenomenological second- and third-order models capable of replicating this behavior, and parameterizes these models. The proposed models succeed in capturing battery discharge behavior accurately over a wide range of discharge rates. To the best of our knowledge, these are two of the simplest published models capable of doing so.

Based on the scenario analysis: the research of auxiliary power unit (APU) system requirement demonstration on high plateaus

Based on the scenario analysis: the research of auxiliary power unit (APU) system requirement demonstration on high plateaus

The Impact of Digital Challenges On the Development of Startups In the Tourism Sector In Algeria

The Algerian government has worked to accelerate digital transformation in recent years, primarily through its orientation towards the knowledge economy and startups, by creating a supportive and framed system and creating many legal frameworks, in addition to taking many incentive measures, which contributed to the development of the startup sector in Algeria, especially tourism startups. However, this sector faces many challenges. This study aims to explore the challenges of the digital transformation of the tourism sector in Algeria through an evaluation research of the challenges of the digital transformation of tourism enterprises in Algeria from the perspective of startup owners. Through qualitative research was conducted through interviews with owners of emerging tourism enterprises to identify the key determinants of digital transformation and critical challenges. Additionally, quantitative research was conducted using a questionnaire to measure these determinants. And quantitative research was conducted by preparing a questionnaire to measure determinants of digital transformation and challenges directed towards owners of startups providing various tourism services, The result of Cronbach’s alpha is 0.795 that indicates that the internal reliability of this set is acceptable. The results showed that most startups in the tourism sector were created in 2019 due to establishing the Ministry of Knowledge Economy and Startups in Algeria in the same year. Most tourism startups are located in the North-Central region due to the region’s favorable ecosystem. The most critical challenges facing digital transformation in Algeria are the need for more supportive institutions and e-governance. The results also show a correlation between a startup’s location and the level of digital transformation challenges. The result indicates that startups located in the High Plateau Center region and the Northeast region face the highest challenges in digital transformation; the results show a correlation between the startup field of activity and the level of digital transformation challenges. The results show that startup activists in direct tourism, e-commerce, and financial services are the most active fields facing higher challenges in digital transformation.

Layered Composites for High Tan Delta Plateau over Wide Temperature Range.

Tan Delta reflects the viscoelastic behavior of materials, particularly polymers. In most cases, a high Tan Delta value is associated with transitions (such as glass transition or melting), enabling effective damping properties near these temperature ranges. However, achieving a high Tan Delta over a broad temperature range is challenging, particularly for engineering applications that involve significant temperature fluctuations. This paper presents a straightforward method using layered composites, where a polymer layer is sandwiched between two highly stretchable elastic fabrics, to achieve a wide Tan Delta plateau (TDP) across a broad temperature range. The three-layer configuration consists of a polymer core embedded between two elastic layers. All samples prepared with this architecture consistently exhibit the TDP. Further investigations examine the influence of factors such as the number of layers and the stretchability of the elastic fabrics. The results demonstrate that the TDP can be effectively tailored for engineering applications using this layered design.

High-Energy-Density All-V2O5 Battery.

Symmetrical batteries hold great promise as cost-effective and safe candidates for future battery technology. However, they realistically suffer low energy density due to the challenge in integrating high specific capacity with high voltage plateau from the limited choice of bipolar electrodes. Herein, a high-voltage all-V2O5 symmetrical battery with clear voltage plateau is conceptualized by decoupling the cathodic/anodic redox reactions based upon the episteme of V2O5intercalation chemistry. As the proof-of-concept, a hierarchical V2O5-carboncomposite (VO-C) bipolar electrode with boosted electron/ion transport kinetics is fabricated, which shows high performance as both cathode and anode in their precisely clamped working potential windows. Accordingly, the symmetrical full-battery exhibits a high capacity of 174 mAh g-1 along with peak voltage output of above 2.9V at 0.5C, remarkable capacity retention of 81% from 0.5C to 10C, and good cycling stability of 70% capacity retention after 300 cycles at 5C. Notably, its energy density reaches 429Wh kg-1 at 0.5C estimated by the cathode mass, which outperforms most of the existing Li/Na/K-based symmetrical batteries. This study leaps forward the performance of symmetrical battery and provides guidance to extend the scope of future battery designs.

Three‐Dimensional Crustal Channel Flows Beneath the Southeastern Tibetan Plateau Revealed by Full‐Waveform Ambient Noise Tomographys

AbstractThe growth process of the southeastern Tibetan Plateau remains a fundamental yet unresolved question. Knowledge of detailed lithospheric structures and their potential linkages with surface features offers crucial insights. Here, we present a high‐resolution 3‐D lithospheric velocity model of the southeastern Tibetan Plateau using full‐waveform ambient noise tomography. Our model reveals two prominent low‐velocity anomalies within the middle and lower crust with new characteristics in spatial distribution: Anomaly 1 lies beneath the plateau, and Anomaly 2 beneath the craton has two branches aligning with the Sichuan‐Youjiang tectonic boundary and the eastern margin of the Emeishan igneous province. Furthermore, these two anomalies appear interconnected at deep crust beneath the northern margin of the Emeishan igneous province. We propose that observed crustal velocity lows indicate partially melted materials transported from the high plateau into the cratonic crust along pre‐existing weak zones, which were reactivated during recent continental deformation.

(Invited) Design Strategy of High-Performance Hard Carbon Anodes for Sodium-Ion Storage

The advancement of hard carbon anodes with high sodium plateau capacities (SPCs) is currently hindered by a paucity of clear materials design principles. Although the pore volume ratio of hard carbon defines the thermodynamic constraints on the theoretical sodium plateau capacities (T-SPCs), exclusive reliance on pore architecture falls short in predicting viable SPCs. In response, our research explores a pivotal kinetic parameter of hard carbons that influences the coefficient of capacity utilization (CCU) of SPCs. We employ a suite of polymeric hard carbons (PHCs) with varied microstructures to achieve our research objectives. Our systematic investigation reveals a pronounced correlation between the intensity ratio of the 2D to G band (I 2D /I G ) in the Raman spectrum and the internal kinetic barrier impeding sodium-ion migration. Leveraging these insights, and by considering both thermodynamic and kinetic facets, we introduce a novel structural gauge – the SPC factor – which serves to quantify the CCU for SPCs. This SPC factor identifies an optimal hard carbon anode configuration that combines a high closed pore volume ratio with a minimized I 2D /I G ratio. By implementing straightforward microstructural modifications to the PHCs guided by our proposed criteria, we have realized significant achievements. Notably, we have attained an SPC of approximately 400 mA h g-1, underscoring the practicality and impact of our strategy in engineering superior hard carbon anodes for sodium-ion batteries. This investigation constitutes a meaningful leap forward, providing a strategic direction for materials design aimed at augmented SPCs and fostering the progression of future sodium-ion battery technologies.

Uncovering the Salt-Controlled Porosity Regulation in Coal-Derived Hard Carbons for Sodium Energy Storage.

Coal is a promising precursor of hard carbon (HC) anodes for sodium-ion batteries (SIBs), by virtue of resource abundance, low cost, and high product yield. However, the concomitant inorganic salt is usually recognized as impurities and plays an obscure and even contradictory effect on the regulation of pore structure in HCs. Herein, a two-step pyrolysis procedure to the representative salty coal is performed, in which the acid washing program is selectively inserted. It is illuminated that salt acts as a template or activating agent for the generation of open pores at low temperatures but inhibits the closure of pores during the following high-temperature carbonization. The optimized HC delivers a reversible capacity of 322.4 mAh g-1, a high plateau capacity of 192 mAh g-1, and an initial coulombic efficiency of 80%, outperforming to most coal-based HCs. Assembled with an NVPOF cathode, the full-cell exhibits a high energy density of 284.7 Wh kg-1. This work not only provides a systematic understanding of salt-dependent pore structure modulation but also practices a simple, cost-effective, and potentially scalable technique for the production of coal-based HCs.

Unravelling the electrochemical characteristics and sodium storage mechanism of pistachio shell derived hard carbon as high plateau capacity anodes by operando Raman spectroscopy and full cell demonstration

Unravelling the electrochemical characteristics and sodium storage mechanism of pistachio shell derived hard carbon as high plateau capacity anodes by operando Raman spectroscopy and full cell demonstration

Cell-Shearing Chemistry Directed Closed-Pore Regeneration in Biomass-Derived Hard Carbons for Ultrafast Sodium Storage.

The closed-pore structure of hard carbons holds the key to high plateau capacity and rapid diffusion kinetics when applied as sodium-ion battery (SIB) anodes. However, understanding and establishing the structure-electrochemistry relationship still remains a significant challenge. This work, for the first time, introduces an innovative deep eutectic solvent (DES) cell-shearing strategy to precisely tailor the cell structure of natural bamboo and consequently the closed-pore in its derived hard carbons. The DES shearing force effectively modifies the pore architecture by simultaneously shearing and dissolving amorphous components to form closed pore cores with adjustable sizes, as well as disintegrating crystalline cellulose through generation of competing hydrogen bonds to elaborately tune the pore wall thickness and ordering. The optimized closed-pore structure featuring appropriate pore size (∼2 nm) and ultra-thin (1-3 layers) disordered pore walls, exhibits abundant active sites and delivers rapid ion diffusion kinetics and high reaction reversibility. Consequently, a high reversible capacity of 422 mAh g-1 at 30 mA g-1 along with an exceptional rate capability (318.6 mAh g-1 at 6 A g-1) are achieved, outperforming almost all previous reported hard carbons. The new concept of cell-shearing chemistry for closed-pore regeneration significantly advances the applications of biomass materials for energy storage.

Enhanced storage performance of a low-cost hard carbon derived from biomass

Enhanced storage performance of a low-cost hard carbon derived from biomass