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Transition metal catalyzed asymmetric hydrofunctionalization of readily available unsaturated hydrocarbons presents one of the most straightforward and atom-economic protocols to access valuable optically active products. For decades, noble transition metal catalysts have laid the cornerstone in this field, on account of their superior reactivity and selectivity. In recent years, from an economical and sustainable standpoint, first-row, earth-abundant transition metals have received considerable attention, due to their high natural reserves, affordable costs, and low toxicity. Meanwhile, the earth-abundant metal catalyzed hydrofunctionalization reactions have also gained much interest and been investigated gradually. However, since chiral ligand libraries for earth-abundant transition-metal catalysis are limited to date, the development of highly enantioselective versions remains a significant challenge.This Account summarizes our recent efforts in developing suitable chiral ligands for iron and cobalt catalysts and their applications in the highly enantioselective hydrofunctionalization reactions (hydroboration and hydrosilylation) of alkenes and alkynes. In ligand design, we envisioned that chiral unsymmetric NNN-tridentate (UNT) ligand scaffolds could promote these enantioselective transformations with earth-abundant metals. Therefore, several types of chiral UNT ligands were designed and prepared in our laboratory, utilizing readily available natural amino acids as chiral sources. In the very beginning, chiral oxazoline iminopyridine (OIP) ligands were proposed and investigated through the rational combination of nitrogen-containing ligand scaffolds. After a systematic survey of the ligand effects, the imine moiety in the rigid OIP ligands was replaced by a conformationally more flexible amine unit, leading to the construction of reactive oxazoline aminoisopropylpyridine (OAP) ligands. Subsequently, imidazoline iminopyridine (IIP) and thiazoline iminopyridine (TIP) ligands were prepared by altering the oxygen atom of oxazoline with nitrogen and sulfur linkers, respectively. To further expand the chiral ligand library, other tridentate ligands containing a twisted pincer, anionic, and nonrigid backbone were also designed and synthesized, including iminophenyl oxazolinyl phenylamine (IPOPA) and imidazoline phenyl picolinamide (ImPPA). The efficacy of these chiral UNT ligands for asymmetric induction in iron and cobalt catalysis has been demonstrated through asymmetric hydrofunctionalization of alkenes and asymmetric sequential hydrofunctionalization of alkynes, which exhibit excellent reactivity as well as high chemo-, regio-, and stereoselectivity with broad functional group tolerance. Notably, highly regio- and enantioselective hydrofunctionalization of challenging substrates, such as 1,1-disubstituted aryl alkenes and terminal aliphatic alkenes, was also achieved. Furthermore, the development of asymmetric sequential isomerization/hydroboration of internal alkenes and sequential hydrofunctionalization of alkynes further demonstrates the synthetic power of these catalytic systems. The chiral enantioenriched products obtained by these methodologies could be potentially utilized in organic synthesis, medicinal chemistry, and materials science. We believe that our continuous efforts in this field would be beneficial to the development of asymmetric earth-abundant metal catalysis.

The N-acyloxyamides were employed as effective N-acyl nitrene precursors in reactions with thioethers under the catalysis of a commercially available Ru(II) complex, from which a variety of sulfimides were synthesized efficiently and mildly. If an allyl group is contained in the thioether precursor, the [2,3]-sigmatropic rearrangement of the sulfimide occurs simultaneously and the N-allyl-N-(thio)amides were obtained as the final products. Preliminary mechanistic studies indicated that the Ru-nitrenoid species should be a key intermediate in the transformation.

High-temperature superconducting (HTS) power equipment and tests at present require operating temperatures higher than the liquid nitrogen (LN2). LN2 is an important cryogenic refrigerant and liquid insulation material, which is widely used in HTS equipment. Although pressurized LN2 can achieve temperatures higher than 77 K, it requires the use of sealed pressure vessels. Thus, a liquid cryogen that can offer temperatures higher than LN2 at atmospheric pressure, excellent electrical insulation performance, and high thermal conductivity has to be explored. Tetrafluoromethane (CF4) is another cryogenic refrigerant and electrical insulation material. The mixture of LN2 and liquid CF4 has excellent thermal properties. When mixed in appropriate proportions, it has a melting point of 50 K and a boiling point of 145 K. The LN2/CF4 mixture is used in the insulating layer of the superconducting energy pipeline to provide a low-temperature environment (85–100 K) for the HTS dc cable. However, the insulation characteristics of the LN2/CF4 mixture at cryogenic temperatures have not been studied, quantitatively. In this article, a test platform is developed to measure the breakdown voltage of the liquid mixture. The dc breakdown voltages of LN2/CF4 liquid mixture under varying mixing proportions are obtained at cryogenic temperature. The insulation failure probability is estimated using a two-parameter Weibull statistical method. The results reveal that the breakdown strength of the LN2/CF4 mixture is lower than that of pure LN2. As the proportion of CF4 increases, the breakdown field strength of liquid mixture first decreases and then increases. When the mole fraction of CF4 is 60%, the average breakdown strength decreases to the lowest value (14.07 kV/mm), about half of that of pure LN2 (28.26 kV/mm). The results of this article can provide a reference for the applications of LN2/CF4 liquid mixture in HTS power equipment and a scheme to expand the working temperature range of superconducting applications.

By employment of a flexible benzoimidazole-type ligand of 1-(2-(1H-benzoimidazol-1-yl)ethyl)-1H-benzoimidazole (beb), two coordination polymers (CPs) of Zn(II) and Co(II) namely, {[Co(beb)(dmglut)]}n (1) and {Zn2(beb)2(hipt)2(H2O)1.5(MeOH)}]n (2) have been produced in the existence of distinct dicarboxylate ligands and metal ions. The measurements of luminescence reveal that the Zn(II)-containing complex 2 can determine 2,4,6-trinitrophenol (TNP) in DMF which possesses high selectivity and sensitivity. For the treatment of Alzheimer’s disease, complexes 1 and 2 were synthesized as above. Their treatment activity on the Alzheimer’s disease was evaluated, and the specific mechanism was investigated as well. Western blot was used to detect the accumulation of Amyloid protein in neurons. Then, the real time RT-PCR was implemented to assess autophagy related genes expression levels.

Aiming to understand fundamentally the alloying effects on the oxidation behaviors of Nb alloys, we combined the first-principles density functional theory and Kinetic Monte Carlo simulations to calculate systematically the binding energies, energy barriers, and diffusion coefficients of oxygen in Nb-X alloys where X = thirty 3d, 4d, and 5d transition metal (TM) elements plus Al and Si in this work. According to the calculated binding energies and energy barriers, we classify the alloying effects into three categories: (a) local short-range trapping effects (X = V, Ti, Cr, Y, Zr, and Hf); (b) local long-range trapping effects (X = Si and Ru); (c) non-local non-trapping effects (X = Mo, W, and Al). Our results show that the solute elements with the short-range trapping effects at near regions had the most effective reduction effects on the O diffusion coefficients while the long-range trapping effects and the non-local effects are less significant but non-negligible. Specifically, the reduction effects of the partial studied alloying elements decrease in the order of Y> V> Ti> Si> Cr> Zr> Hf> Al> Mo> Ru> W. For all the studied 30 TM elements, the diffusion coefficients were calculated for O at the near regions of the solute atoms and their trends were discussed. These intrinsic alloying effects on the oxygen diffusion in Nb alloys provide the theoretical evidence for the rational composition design of oxidation-resistant Nb alloys.

A new Co(II)-containing coordination complex with the chemical formula of [CoL2(SCN)2](H2O)2 (1) has been assembled from the Co(NO3)2·6H2O with a tripyridyltriazole ligand 3-(2-pyridyl)-4-(4-pyridy...

To make a reliable reconstruction of past climate from soil-surface modern pollen, it is necessary to reduce the sources of error. In this paper, pollen percentages of the sub-continental scale modern pollen-climate dataset from China and Mongolia (with 68% soil-surface samples) are homogenized at various spatial scales. A tailored calibration-set is then applied to lake sediment-surface pollen assemblages from north-central China to evaluate their predictive power. Results indicate that spatial homogenization of modern pollen percentages can increase the proportion of inertia explained by climatic variables in CCA and improve the model performance of leave-one-out cross-validation using WA-PLS. Soil-surface pollen assemblages can thus be employed into a calibration-set for reliable climate estimation and they perform better when the calibration-set has been locally homogenized. Small-scale (e.g., radii 2, 5, or 10 km) homogenization reduces the local noise in soil-surface pollen assemblages and improves the cross-validated performance, while broader scale homogenization (more than 20 km radius) blurs the pollen-climate relationship. Lake sediment-surface pollen assemblages from close to the shore could contain pollen grains transported by rivers or from the shore vegetation and thus fail to represent regional climate well like the assemblages from the central part and deep-water area of lake.

The Asian monsoon (AM) played an important role in the dynastic history of China, yet it remains unknown whether AM-mediated shifts in Chinese societies affect earth surface processes to the point of exceeding natural variability. Here, we present a dust storm intensity record dating back to the first unified dynasty of China (the Qin Dynasty, 221–207 B.C.E.). Marked increases in dust storm activity coincided with unified dynasties with large populations during strong AM periods. By contrast, reduced dust storm activity corresponded to decreased population sizes and periods of civil unrest, which was co-eval with a weakened AM. The strengthened AM may have facilitated the development of Chinese civilizations, destabilizing the topsoil and thereby increasing the dust storm frequency. Beginning at least 2000 years ago, human activities might have started to overtake natural climatic variability as the dominant controls of dust storm activity in eastern China., How the Asian monsoon, earth surface processes and human development interact is not well known. Here, a new record of dust storm intensity shows a relationship between the stability of dynasties and dust storm activity for the last ~2200 years, which argues for a strong human control of dust storms in East Asia over this time.

Renal clearance (CLr) plays an essential role in the elimination of drugs. In this study, 636 compounds were obtained from various sources to develop in silico models for the prediction of CLr. Stepwise multiple linear regression and random forest regression methods were employed to build global models and local models according to ionization state or net elimination pathways. The local models toward compounds undergoing different net elimination pathways showed good predictive power: the geometric mean fold error was close to 2, indicating the clearance of most compounds could be predicted within a 2-fold error range. Six classification methods were used to construct classification models. However, the performance of these classification models was less than satisfactory, and the mean accuracy of the top five models in test sets was 0.65. Moreover, qualitative analysis of physicochemical profiles between compounds undergoing different net elimination pathways revealed that compounds with higher lipophilicity tended to be reabsorbed more easily and showed lower CLr, while compounds with higher values of polar descriptors tended to secrete more easily and showed higher CLr.

An efficient cobalt-catalyzed Z to E isomerization of β-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.

High complexity, meaning a model in which components interact in multiple ways and follow certain local rules, is a huge challenge for brain research. This paper presents a semantic vector-driven closed-loop model, namely THINKING-LOOP, for brain computing to improve the understanding and development of complex cognition. The proposed model is a three-layer fusion of data, information and knowledge with human intelligence, which exploits ontological knowledge modeling, rule-based reasoning and a human-computer interaction mechanism. The interaction and collaboration within the model depend on a pair of complementary schemes in a loop: the top-down scheme from the knowledge layer to the data layer that is used to search for stable cognitive patterns; and the bottom-up scheme from the data layer to the knowledge layer that is used to deeply analyze cognitive functions. As a key factor, human beings participate in the whole learning process of the model, which in turn assists human beings to make decisions. To verify the applicability of the present model in cognitive research, a series of fMRI experiments and analytic methods (e.g. statistical tests and network topology analysis) were conducted. The results show that the proposed model is able to take into account the characteristics of different types of brain patterns and cognitive functions, thereby achieving reasonable decision-making level.

Since its discovery ferroelectricity has been an intriguing phenomenon in materials science and is usually observed in a single ferroelectric material. In this study, it is shown that ferroelectriciy can also occur at the interface between two non-ferroelectric materials, a polymer and silicon, and interfacial ferroelectric-like behavior is demonstrated. Sulfonic functional groups on the polymer establish electrochemically switchable dipoles, which are considered to be the origin of ferroelectric polarization and are observed in an atom-thick polar region at the interface. Above room temperature polarization hysteresis loops with long term stability, thermal stability, reliable switching reproducibility and long information retention directly on rigid and flexible silicon substrates are demonstrated. This exotic ferroelectric phenomenon extends polarization switching beyond singular materials and has the potential to advance the design of new ferroelectric devices.

Knowledge of historical changes in moisture within semi-arid and arid regions is the basis of climatic change predictions and strategies in response to long-term drought. In this study, a multiproxy peat record with high-resolution from Sichanghu in the northern Tianshan was used to document the changes in vegetation and climate over the past 450 years in the arid Central Asia. The pollen, grain size, and loss on ignition (LOI) records indicate that the productivity of local peat began to increase at ∼1730 AD. The vegetation in the Sichanghu area experienced several transitions, from temperate desert to dense desert, marsh meadow, and steppe desert vegetation. The climate in the study area was extremely dry during the early stages of the Little Ice Age (LIA) (before 1730 AD) and relatively wet during the late stages (1730–1880 AD). The inferred changes in the moisture conditions of the Sichanghu peatland since the LIA may have been controlled by the extent of Arctic sea ice, the North Atlantic Oscillation, and the Siberian High via the connections of large-scale atmospheric circulations such as the Westerlies.

Purpose The purpose of this paper is to use body shape analysis and develop a 3D virtual body formation and deformation model that can accurately express size and shape. Design/methodology/approach In this paper, 1,882 sets of direct measurement data of Korean women in their 20s (19–29 years) were analyzed. These data sets were sourced from the sixth and seventh “Size Korea” anthropometric survey data. Through body shape analysis, the authors classified them into seven body types and selected their representative bodies. A 2D image based on the height, breadth, depth and length was first formed, and the representative virtual body was modeled using the polygon technique. The authors calculated the grading ratios for each body type according to the clothing sizing system, and modified the virtual body size type by morphing technique. Findings In order to accurately evaluate the fit in a virtual fitting system, it is necessary to study the body size and shape of the target age; this makes it possible to form virtual body reflecting the size and shape. Originality/value In this paper, the authors propose a new 3D virtual body formation method that is more accurate in shape and size compared to the present system. Through this, it will be possible to grasp the accurate simulation state in the virtual fitting system, and thereby evaluate the accurate fit.

The natural environment provides material essentials for human survival and development. The characteristics, processes, regional differentiation and forcing mechanisms of the elements of the natural environment (e.g. geomorphology, climate, hydrology, soil, etc.) are the main objects of research in physical geography. China has a complex natural environment and huge regional differentiation and therefore it provides outstanding reserach opportunities in physical geography. This review summarizes the most important developments and the main contributions of research in the physical geography and human living environment in China during the past 70 years. The major topics addressed are the uplift of the Tibetan Plateau and the evolution of its cryosphere, the development of fluvial systems, the acidification of the vast arid region of the Asian interior, variations in the monsoon and westerly climate systems on multiple timescales, the development of lakes and wetlands, the watershed system model, soil erosion, past human-environment interactions, biogeography, and physical geographic zonality. After briefly introducing international research developments, we review the history of research in physical geography in China, focusing on the major achievements and major academic debates, and finally we summarize the status of current research and the future prospects. We propose that in the context of the national demand for the construction of an ecological civilization, we should make full use of the research findings of physical geography, and determine the patterns and mechanisms of natural environmental processes in order to continue to promote the continued contribution of physical geography to national development strategies, and to further contribute to the theory of physical geography from a global perspective.

Beam stability is a critical figure of merit of synchrotron light sources and free electron lasers [1–5]. Beam stability is also an active topic [6] for next-generation storage ring light sources; ...

Surface engineering of crystalline silicon (c-Si) is the core of Si-based semiconductor devices. The current commercially available c-Si solar cells achieve this by making use of a conventional thin dielectric film passivation system (TDFPS), including SiO2, Al2O3, SiNx:H and hydrogenated amorphous silicon (a-Si:H) in industry. However, the TDFPS requires high-vacuum and/or high-temperature conditions, which hinders efforts to further reduce the costs of device fabrication. A revolutionized approach to circumvent these issues involves the replacement of TDFPS with new material system which can also achieve high-quality passivation on c-Si surface. Here, we successfully establish and implement a functional group passivation system (FGPS) using a series of functional materials with a sulfonic functional group -SO3H, such as ‘poly(2-acrylamido-2-methylpropanesulfonic acid)’ (PAMPS) and ‘polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene, sulfonated, cross-linkable’ (PS-b-PERB), which can achieve a highly effective passivation on Si surface, resulting in power conversion efficiencies up to 20% when they are applied in the front surface engineering of interdigitated back contact (IBC) solar cells. Furthermore, the FGPS materials inherently allow passivation layer fabrication in lowtemperature and high-vacuum-free conditions. This work provides novel low-cost material strategies without compromise of performance for c-Si surface engineering in the future Si-based photovoltaics.

The ‘westerlies-dominated climatic regime’ (WDCR) in the present interglacial period was proposed because precipitation/moisture variations between arid central Asia and mid-latitude monsoonal Asia are out-of-phase or anti-phased on different timescales during the Holocene. In this study. we first review the development of the theoretical framework of the WDCR, and then outline the boundary of its core area: from the Caspian Sea in the west to the western Hexi Corridor in the east, with the northern and southern limits coinciding with the domain of arid central Asia. Next, we present a synthesis of multiple lines of evidence for the occurrence of the WDCR on multi-millennial (‘sub-orbital’ herein) to decadal timescales during the Holocene. Finally, we examine the possible physical mechanisms responsible for the WDCR. We find that external factors (insolation changes induced by orbital factors) generated the WDCR on a sub-orbital timescale, whereas a circum-global teleconnection/Silk Road pattern was the most significant factor responsible for the WDCR on centennial and decadal timescales. The study provides a comprehensive summary of the development of our knowledge of the WDCR over the past several decades, together with a tentative theoretical framework for understanding climatic and environmental changes within its region of influence. In addition, it forms a scientific basis for environmental management and ecological restoration in this arid region in the context of global warming.

Climatic instability, especially on decadal to multi-decadal time scales, has a profound impact on societal development and human welfare in semi-arid and arid regions. Previous work suggested that arid northwestern China was characterized by a dry Medieval Warm Period (MWP, from ca. 1000 to 1300 AD) and a wet Little Ice Age (LIA, from ca. 1400 to 1850 AD), but there is a lack of studies addressing the issue of climatic variability during the last millennium. Here, we present results from a diverse range of proxy records from northwestern China with the aim of evaluating the time variation of hydroclimatic variability during the MWP and LIA. Within the context of an overall cold climate, we detected a pattern of higher moisture variability during the LIA compared to the MWP. A comparison of the proxy records of climatic instability during the LIA from northwestern China with the major modes of SST and atmospheric variability, which affect moisture/precipitation in Asia, suggests that the instability of the North Atlantic Oscillation (NAO) from middle- to high-latitude regions during the LIA was a major driving factor. The westerlies may play an important role in linking the unstable climatic conditions observed in the above-mentioned regions. Our results support the concept that climatic instability was above the norm during cold periods, in contrast with present observations that demonstrate the occurrence of increasingly extreme climatic events with ongoing global warming.

Recently, there have been rapid advances in silicon heterojunction (SHJ) solar cells based on dopant-free contacts. However, there is no better choice to achieve flexible energy band alignment than to choose different materials. Here, Zn(O,S) materials, whose energy band structure can be flexibly tuned by a continuously adjustable ratio of S/Zn, combined with a low work function Mg layer, contribute a novel electron-selective contact (ESC) for Si-based dopant-free heterojunction solar cells. The tunability of the energy band structure of the ESC is confirmed by ultraviolet photoelectron spectroscopy (UPS) and photoluminescence (PL) spectroscopy, originating from the modulation of chemical composition by the change in oxygen partial pressure using reactive sputtering, which is linked to the Zn(O,S)/n-Si interface properties and the corresponding solar cell device performances. Zn(O,S) films with a high ratio of S/Zn present a small conduction band offset (CBO) and a large valence band offset (VBO) at the Zn(O,S)/n-Si interface, which reduces minority carrier recombination and favors majority carrier transport, and then contributes to an absolute efficiency gain of 1.9% compared with the reference cell. In contrast, the Zn(O,S) films with a low ratio of S/Zn present a large CBO at the Zn(O,S)/n-Si interface, which makes the solar cell J–V curve exhibit an anomalous S-shape with a degraded fill factor (FF). A similar J–V distortion trend is found in simulated results when the value of the CBO at the Si/Zn(O,S) interface goes from small to large. These results offer a concept of energy-band-tunable ESCs for constructing new dopant-free contacts to realize high-performance photovoltaic devices.

The long-term cooling or warming trend is one of the most important aspects of Holocene paleoclimatic research. However, there are currently significant discrepancies among climatic simulation results, sedimentary and synthesized Holocene temperature records. These discrepancies call for new Holocene temperature records with a robust chronology and unambiguous indicative significance. Here, we present a ca. 45-year-resolution alpine peat α-cellulose carbon isotopic (δ13C) record from the Altai Mountains in central Asia. The chronology of the record has been well-constrained by 22 AMS 14C dates of the peat α-cellulose samples. Based on detailed modern-process study results, the indicative significance of the record has been carefully determined as summer temperature indicator. The record reveals an overall trend of increasing summer temperature for the past ca. 11 ka with a warmer early (from ca. 8–6 ka BP) and late (from ca. 4–0 ka BP) Holocene and colder middle Holocene (from ca. 6–4 ka BP). The general pattern of a warmer early and late Holocene and colder middle Holocene is consistent with previously reported temperature records from central Asia, the Tibetan Plateau, and North China. The long-term warming trend in our summer temperature record is consistent with recently reported winter temperature records from high latitudes of continental Eurasia. All these results further support the reliability of our summer temperature record from central Asia. The better understandings about the Holocene temperature history and its possible driven mechanism(s) can be benefited potentially from more reliable Holocene temperature records, including our record reported in this paper.

A facile and efficient synthesis of 1,3-diketones was developed by the gold(i)-catalyzed regioselective hydration of ynones at room temperature. This methodology employed 2.5 mol% of PPh3AuCl and 3 mol% of AgOTf as a simple catalytic system without any special phosphine ligand and was compatible with a wide range of substrates, giving rise to 1,3-diaryl, 1-alkyl-3-aryl-, and 1,3-dialkyl-1,3-diketones in up to quantitative yields in open flask reactions. This methodology could be readily scaled up to gram-scales.

Traffic accidents may pose a high risk with respect to human travel safety. In order to improve the safety of travelling, an insight into the traffic accidents is needed. This requires a practical and specifically approach when it comes to modelling for traffic accidents. This paper presents a traffic accident model based on self-exciting processes, which describes the specific phenomena and problems in traffic accidents. The research focuses on the stationary condition, reliability and safety analysis of the traffic network in a certain city or the traffic situation in a certain area. First, a traffic accident model based on self-exciting processes is developed, and secondly, the stationary condition of the model is studied, which is used to analyze the reliability and safety of the traffic network in a certain city or the traffic situation in a certain area. In addition, the probability and related characteristics for traffic process are evaluated by simulation methods. The traffic accident model is developed with the use of self-exciting processes. Maximum Likelihood Estimate (MLE) is used for the parameter estimations of the traffic accident model. Finally, a numerical example is presented, in which the traffic accident model developed is applied to the simulation data.

Crystalline silicon (c-Si) solar cells remain dominant in the photovoltaic (PV) market because of their cost-effective advantages. However, the requirement for expensive vacuum equipment and the power-hungry thermal budget for surface passivation technology, which is one of the key enablers of the high performance of c-Si solar cells, impede further reductions of costs. Thus, the omission of the vacuum and high-temperature process without compromising the passivation effect is highly desirable due to cost concerns. Here, we demonstrate a vacuum-free, room-temperature organic Nafion thin-film passivation scheme with an effective minority carrier lifetime (τeff) exceeding 9 ms on an n-type c-Si wafer with a resistivity of 1–5 Ω·cm, corresponding to an implied open circuit voltage (iVoc) of 724 mV and upper-limit surface recombination velocity (SRV) of 1.46 cm/s, which is a level that is in line with the hydrogenated amorphous Si film-passivation scheme used in the current PV industry. We find that the Nafio...

Human activities over the last ∼100 years have fundamentally changed the biogeochemistry of the global nitrogen cycle. For example, increased nitrogen deposition from industrial and agricultural sources has been linked to lake acidification and nutrient fertilization, and thus it has the potential to significantly influence lake ecosystems. Records of anthropogenic nitrogen deposition from alpine lakes are sparse in China, which limits our understanding of its effects on remote alpine lake ecosystems. In this study, we analyzed multiple geochemical proxies at Tianchi Lake (2430 m a.s.l.), which is part of the Liupan Mountains National Nature Reserve in the central Chinese Loess Plateau (CLP). We measured total nitrogen (TN) concentrations, C/N ratios and nitrogen stable isotope ratios (δ15N), as well as a biological proxy (spectrally-inferred chlorophyll a), from a well-dated sediment core spanning the past ∼200 years. Our aim was to examine anthropogenic nitrogen deposition to the lake and to assess its implications for lake primary production. We found that δ15N was stable prior to ∼1980, but it decreased significantly thereafter. This is consistent with documented changes in anthropogenic nitrogen deposition over the past ∼200 years, and it indicates that the δ15N record of Tianchi Lake likely reflects anthropogenic nitrogen deposition, at least in this region. Prior to ∼1980, the trend in primary production of Tianchi Lake agrees with the trend of reconstructed regional temperature, when reactive nitrogen emissions in China were very low. This suggests that temperature was likely the main factor driving lake primary production before ∼1980. Primary production has increased significantly since ∼1980, consistent with the continued rising temperature and with enhanced nitrogen deposition, indicating that both factors are simultaneous drivers. Although the current data for Tianchi Lake are insufficient to unequivocally determine which of the two stressors is more important after the 1980s, temperature likely played the more significant role in driving primary production. This is because the lake is phosphorus-limited today, and in addition there is a strong association between temperature and chlorophyll a over the past ∼200 years. Continuing global warming and increasing nitrogen deposition in the future will likely further affect the fragile alpine ecosystems in the region.

Computed tomography urography imaging is routinely performed to evaluate the kidneys. Kidney 3D segmentation and reconstruction from urographic images provides physicians with an intuitive visualization way to accurately diagnose and treat kidney diseases, particularly used in surgical planning and outcome analysis before and after kidney surgery. While 3D fully convolution networks have achieved a big success in medical image segmentation, they get trapped in clinical unseen data and cannot be adapted in deferent modalities with one training procedure. This study proposes an unsupervised domain adaptation or translation method with 2D networks to deeply learn urographic images for accurate kidney segmentation. We tested our proposed method on clinical urography data. The experimental results demonstrate our proposed method can resolve the domain shift problem of kidney segmentation and achieve the comparable or better results than supervised learning based segmentation methods.

Herein, we report an efficient method for the synthesis of (Z)-β-halovinyl ketones through a one-pot Sonogashira coupling and hydrohalogenation reaction promoted by palladium-copper catalyst and Brønsted acid. The ynone intermediates are generated in situ from readily available acid chlorides and terminal alkynes at room temperature, which are directly converted to (Z)-β-halovinyl ketones by treating with triflic acid. This method avoids the use of an external halogen source and features broad substrate scope, high yield, and good to excellent stereoselectivity.

The δ13C, δ18O and Sr/Ca series of a stalagmite from Kyrgyzstan, provide so far, the highest-resolved (~3 yr) and most precisely-dated (~6‰) precipitation record in Arid Central Asia covering the middle to late Holocene. The record reveals a 640-yr megadrought between 5820 and 5180 a BP, which likely delayed prehistoric trans-Eurasian cultural exchange along the proto-Silk Road.Arid Central Asia (ACA), with its diverse landscapes of high mountains, oases, and deserts, hosted the central routes of the Silk Roads that linked trade centers from East Asia to the eastern Mediterranean. Ecological pockets and ecoclines in ACA are largely determined by local precipitation. However, little research has gone into the effects of hydroclimatic changes on trans-Eurasian cultural exchange. Here, we reconstruct precipitation changes in ACA, covering the mid-late Holocene with a U-Th dated, ~3 a resolution, multi-proxy time series of replicated stalagmites from the southeastern Fergana Valley, Kyrgyzstan. Our data reveal a 640-a megadrought between 5820 and 5180 a BP, which likely impacted cultural development in ACA and impeded the expansion of cultural traits along oasis routes. Instead, it may have diverted the earliest transcontinental exchange along the Eurasian steppe during the 5th millennium BP. With gradually increasing precipitation after the megadrought, settlement of peoples in the oases and river valleys may have facilitated the opening of the oasis routes, “prehistoric Silk Roads”, of trans-Eurasian exchange. By the 4th millennium BP, this process may have reshaped cultures across the two continents, laying the foundation for the organized Silk Roads.

Lipoxygenases (Loxs) are dioxygenases that play an important role in plant growth and defense. Loxs affect flour processing quality in common wheat (Triticum aestivum). We conducted a genome-wide association study (GWAS) that identified 306 significant single-nucleotide polymorphisms (SNPs) related to Lox activity in Chinese wheat accessions. Among them, a novel lipoxygenase-encoding (Lpx) gene, TaLpx-B4, was detected on chromosome 3B in a biparental population. Analysis of mutant wheat lines induced using ethyl methanesulfonate confirmed the role of TaLpx-B4 in modulating Lox activity. A phylogenetic tree of various plant Lpx genes indicated the predominance of the 9-Lpx type in common wheat. Further analysis revealed conserved intron number, exon length, and motif number in the TaLpx gene family. GWAS, linkage mapping, and gene annotation collectively showed that 14 out of 29 annotated TaLpx genes played a critical role in regulating Lox activity in the Chinese wheat accessions. Transgenic wheat grains with knockdown of Lpx family genes by RNAi showed significantly lower Lox activity than the wild type. One TaLpx-RNAi line had significantly reduced starch content and dough stability, and thus possessed relatively superior biscuit quality in soft wheat. Further analysis of the transcriptome, lipid components, and other metabolites revealed that knockdown of TaLpx genes significantly increased biscuit quality via changes in unsaturated fatty acid content as well as in starch, sucrose, and galactose metabolism. Our results provide new insights into the role of the TaLpx gene family that will be beneficial in improving soft wheat flour quality.

The use of carbon nanotubes (CNTs) in photovoltaics could have significant ramifications on the commercial solar cell market. Three interrelated research directions within the field are crucial to the ultimate success of this endeavor; 1) separation, purification, and enrichment of CNTs followed by 2) their integration into organic solar cells as a photosensitive element or 3) in silicon solar cells as a hole selective contact. All three subtopics have experienced tremendous growth over the past 20 years and certainly the performance of the silicon‐based cells is now rapidly approaching that of those on industrial production lines. With a view to these three research areas, the purpose of this Progress Report is to provide a brief overview of each field but more importantly to discuss the challenges and future directions that will allow CNT photovoltaics to move out of the research lab and into end user technology. These include efforts to upscale CNT purification, improvements in power conversion efficiency, increased light absorption, the identification of new material combinations, passivation strategies, and a better understanding of charge separation and energy transfer within these systems.

The shrinkage of the Aral Sea started in the 1960s, and it has been continued for decades due to arguably both human and natural causes. However, the change of the Aral Sea in the post-Soviet era and its correlations with other changes in the extent of the basin have yet to be fully investigated. Here, we studied the land cover dynamics of the entire Aral Sea basin during 1992–2015 from the perspective of the surrounding environment, in order to investigate the causes of the Aral Sea further shrinkage in recent years. We used the annual Climate Change Initiative (CCI) land cover dataset to provide a spatiotemporally consistent delineation of land cover throughout the period. We found that: (1) In recent years, the Aral Sea continued shrinkage, approximately 50.38% of its water area in 1992 had dried out and turned into bare land by 2015. (2) The cultivated land area remained stable with a slight increase during the period, suggesting that no large-scale abandonment or expansion of farming extent occurred in the post-Soviet era. (3) Among other land types, urban areas are small and slightly expand at a rate of 0.024 × 104 km2/year, suggesting urbanization, and likely contribute to more water consumption. Our investigation also found that climate warming increased the upstream runoff, which has a positive effect on the water supply of the Aral Sea. The impact of human activity on the Aral Sea is more pronounced than climate change. Therefore, the continued shrinkage of the Aral Sea was likely due to high water consumption of agriculture continues to exert the influence that existed in the 1960s. Other factors, such as urbanization have exacerbated this effect. The study examined the continued shrinkage of the Aral Sea in post-Soviet era, to provide an insight into the driving factors of the complex and still controversial Aral Sea crisis.

The gradient-weighted class activation mapping (Grad-CAM) method can faithfully highlight important regions in images for deep model prediction in image classification, image captioning and many other tasks. It uses the gradients in back-propagation as weights (grad-weights) to explain network decisions. However, applying Grad-CAM to embedding networks raises significant challenges because embedding networks are trained by millions of dynamically paired examples (e.g. triplets). To overcome these challenges, we propose an adaptation of the Grad-CAM method for embedding networks. First, we aggregate grad-weights from multiple training examples to improve the stability of Grad-CAM. Then, we develop an efficient weight-transfer method to explain decisions for any image without back-propagation. We extensively validate the method on the standard CUB200 dataset in which our method produces more accurate visual attention than the original Grad-CAM method. We also apply the method to a house price estimation application using images. The method produces convincing qualitative results, showcasing the practicality of our approach., WACV 2020 camera ready

With the development of novel n-type crystalline silicon based solar cells, low work function metals compatibility for rear metallization without heat treatment process motivate much attention. In this study, we demonstrate contact characteristics and performances of n-Pasha solar cells with Hf/Ag, Mg/Ag and Ag as rear metallization layers. n-Pasha solar cells with Mg contact layer achieved a series resistance of 0.24 Ω in contrast to Hf of 0.82 Ω and Ag of 1.52 Ω, respectively. It is visible that n-type crystalline silicon solar cell with Mg rear metallization exhibits excellent contact characteristic. In contrast to Ag contact, the open circuit voltage and fill factor of Mg contact were increased by 9% (relative) with a gain of 47 mV and 1.3% (absolute), respectively. The resultant power conversion efficiency of Mg contact obtained a gain of 1.5% (absolute) and 10.5% (relative) compared with Ag contact. Thus, this new technique can be exactly catering for demands of rear metallization for novel n-type silicon based solar cells.

An organic semiconductor composite thin film, 5,6,11,12-tetraphenylnaphthacene:dimethyl sulfoxide (rubrene:DMSO), is fabricated by dissolving rubrene powder into the DMSO solvent to form the precur...

Changes in global climate intensify the hydrological cycle, directly influence precipitation, evaporation, runoff, and cause the re-distribution of water resources in time and space. The aridity index (AI), defined as the ratio of annual precipitation to annual potential evapotranspiration, is a widely used numerical indicator to quantify the degree of dryness at a given location. This study examined the effects of climate change on AI in China during 1961-2015. The results showed that the nationally averaged AI experienced a notable interdecadal transition in 1993, characterized by increasing AI (wetter) between 1961 and 1993, and decreasing AI (drier) after 1993. Overall, the decreased solar radiation (solar dimming) was the main factor affected the nationally averaged AI during 1961-1993, while the relative humidity dominated the variations of nationally averaged AI during 1993-2015. However, the roles of individual factors on the changes in AI vary in different subregions. Precipitation is one of the important contributing factors for the changes of AI in almost all subregions, except the Mid-Lower Yangtze and Huaihe basins. Solar radiation has been significantly decreased during 1961-1993 in South China, Southwest China, Mid-Lower Yangtze and Huaihe basins, and the Tibetan Plateau. Therefore, it dominated the trends of AI in these subregions. The relative humidity mainly affected the Mid-Lower Yangtze and Huaihe basins, Southwest China, and the Tibetan Plateau during 1993-2015, hence dominated the trends of AI in these subregions. The changes of temperature and wind speed, however, played a relatively weak role in the variations of AI.

Proxy-based reconstructions of Holocene temperature show that both the timing and magnitude of the thermal maximum varied substantially across different regions. Given the ‘Holocene temperature conundrum’, it is becoming increasingly important to reconstruct seasonal temperature variations. As a major component of the global monsoon system, the Indian summer monsoon (ISM) transports moisture and heat from the tropical oceans to higher latitudes and thus it has substantial socioeconomic implications for its regions of influences. We developed a well-dated, pollen-based summer temperature record (mean July; MJT) for the last 14,000 years from Xingyun Lake in southwest China, where the climate is dominated by the ISM. MJT decreased during the Younger Dryas, increased slowly to high values during 8000–5500 yr BP, and decreased thereafter. The MJT record differs from that inferred using carbonate oxygen isotopes (δ18O) from the same sediment core. The latter record reflects variations in monsoon precipitation, with highest precipitation during the early Holocene (11,000–6500 yr BP). We propose that summer temperature and precipitation in southwest China were decoupled during the early Holocene. Both MJT and monsoon precipitation decreased after the middle Holocene, tracking the trend in boreal summer insolation. We suggest that greater cloud cover, associated with high precipitation and generated by a strong summer monsoon, may have depressed early Holocene temperatures that would otherwise be driven by greater summer insolation. Melting ice sheets in high-latitude regions and high concentrations of atmospheric aerosols during the early Holocene may also have contributed, in part, to the relatively cool summer temperatures.

Large-scale palaeoclimate reconstructions can be very sensitive to the proxy records they are based on, and hence to the criteria used to select proxy records. Data selection rarely follows objective criteria that are applicable to all types of proxies, including both low- and high-resolution records. Thus, there is a need for a uniform and transparent approach to assess the suitability of input proxy data for a reconstruction. Here, we develop classification criteria that are applicable to multiple proxy types and evaluate different selection strategies using a network of 62 millennium-long terrestrial hydroclimate proxy records from Monsoon Asia. Our results reveal that robust evidence for a coherent climate signal and high dating accuracy are important criteria for benchmarking the suitability of each proxy record. We determine these criteria by reviewing the literature for each record (rather than screening against instrumental data). We show that the proposed selection approach can yield a network with a stronger common signal. By evaluating the uncertainty and centennial variability of composite reconstructions, from differently selected subsets of the proxy network, it appears beneficial to use suitable proxies stemming from different archives, as well as having a dense network of proxy sites. We suggest that future large-scale palaeoclimate reconstructions might be improved by evaluating proxy networks according to the universal categories presented here and, if indicated, removing less suitable records. This will strengthen the climate signal in the final reconstruction, allowing more precise inferences about past climate variability and more robust comparisons with climate model simulations.

It is usually difficult to obtain the radial levitation force of the radial-type superconducting magnetic bearing (SMB) due to the massive numerical calculations and the sophisticated experimental measurements. This study presents a method for fast calculating the radial levitation force of radial-type SMB, which is based on the infinitesimal method and the 2D finite-element method. During the modelling, the radial-type SMB is assumed to be composed circumferentially of infinite superconductor-permanent magnet (SC-PM) infinitesimals with shape of rectangular thin slice. The dependence of levitation force for the SC-PM infinitesimal on the air-gap length between the SC stator and the PM rotor can be obtained using the 2D finite-element model established in Cartesian coordinate system. Moreover, a simplified analytical model of calculating radial levitation force is developed based on the infinitesimal method and the circumferential distribution formula of non-uniform air-gap when the PM rotor exhibits radial eccentricity. The results of theoretical calculation and experimental measurement of radial levitation force show a good agreement, which verifies the feasibility of the proposed method. It has the advantages of fastness and easiness, and can be used as a theoretical tool for the design, optimisation and performance prediction of the radial-type SMB.

Alpine lakes not only provide internationally important habitats for endangered species, they also play a crucial role in the regional water balance. Unfortunately, a rapid loss of alpine lakes in China has occurred in recent decades; however, intensive human activities, together with regional differences in the responses of lakes to climate change, has impeded our understanding of the contribution of climate change to the loss of these lakes. To better understand how alpine lakes will evolve with continuing global warming, we used the analysis of new sedimentary proxies from Lake Gonghai, an undisturbed alpine lake, together with a review of published records, to reconstruct variations in integrated lake status since the last deglaciation. From 14,660–11,890 cal. yr BP the lake was in the most unstable state, indicated by the highest amplitude fluctuations in lake level and the within-lake environment. The lake status experienced clear millennial-scale changes. During the early and middle Holocene (11,890–3200 cal. yr BP), the most stable lake status occurred, consistent with the highest precipitation levels. Owing to the highest level of freshwater influx in the middle Holocene (8–5 ka), the lake water was the deepest and most acidic. At this time, the dense vegetation cover resulted in maximum catchment stability and the lowest level of soil erosion, and hence the lowest sediment accumulation rate. From 3200 cal. yr BP, decreasing mean annual precipitation resulted in a moderately stable lake status, a shallow water depth and more alkaline lake water. The sparse vegetation cover caused a dramatic increase in the erosion rate and hence in the sediment accumulation rate. We infer that variations in local humidity were the major control on the integrated lake status during the last ~14,600 cal. yr BP. With the anticipated progression of global warming, the status of the alpine lakes in the region may continue to deteriorate and appropriate mitigation strategies are imperative.

The aim of this paper was to prepare purified fractions of polysaccharides from Monetaria moneta Linnaeus and further compare their characteristics and antioxidant activities. Firstly, three novel purified fractions, named MM-P1, MM-P2 and MM-P3, were successfully prepared by a DEAE-Sepharose fast-flow column. Then, their characteristics were compared using chemical testing, FT-IR, GC and HPGPC. The results suggested that MM-P3 had higher molecular weights than MM-P1 and MM-P2. MM-P1 was consisted of glucose, MM-P2 was consisted of glucose and xylose, and MM-P3 was comprised of glucose, xylose and mannose. Differed from MM-P1 and MM-P2, MM-P3 had sulfuric radical and uronic acid groups. Finally, their antioxidant activities were also compared. We found that MM-P3 exhibited better antioxidant bioactivities than MM-P1 and MM-P2. The data demonstrated that three purified fractions derived from different adsorption capacity of DEAE-Sepharose fast-flow column possessed different structural characteristics and antioxidant activity.

In this study, MgNd intermetallic is deposited as a thin film using magnetron sputtering. Ultraviolet photoelectron spectroscopy (UPS) is employed to determine the work function of the MgNd thin film. It is found that the MgNd thin film has a low work function of 3.5 eV, leading to its application in hybrid poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS)/n-Si solar cells as a back surface field (BSF) material. By introducing a MgNd thin film into the back Si/electrode interface of a hybrid solar cell, obvious improvements in the open circuit voltage (Voc) and fill factor (FF) of the device are observed, leading to an increase by more than 26% in power conversion efficiency (PCE). Temperature-dependent current density–voltage (J-V) and Voc-light intensity measurements demonstrate that the introduction of a MgNd thin layer increases the built-in voltage at the rear interface and decreases the recombination current in the device. These improvements are attributed to the efficacy of the MgNd thin film as a BSF by reducing minority carrier recombination and enhancing majority carrier transport.

A good quality ZnS thin film has been functionalized as back surface field (BSF) in Si solar cells. Compared to Si solar cells without BSF, the solar cells with ZnS BSF presents about 50% increase of the power conversion efficiency (PCE). This improvement stems from a downward energy band at the c-Si (n)/ZnS interface, which forms an interfacial field-effect. This field impedes the minority carrier recombination and favors the majority carrier transport, so that open circuit voltage and fill factor of the device are increased. Additional electrode of low work function (e.g. Mg) can further enhance the performance of the solar cell with the ZnS BSF thanks to second downward energy band at ZnS/electrode interface. This work demonstrates that the compound thin film can act as a candidate for a functional layer in Si solar cells.

This study examines the shifts in terrestrial climate regimes using the Koppen–Trewartha (K–T) climate classification by analyzing the Community Earth System Model Last Millennium Ensemble (CESM-LME) simulations for the period 850–2005 and CESM Medium Ensemble (CESM-ME), CESM Large Ensemble (CESM-LE) and CESM with fixed aerosols Medium Ensemble (CESM-LE_FixA) simulations for the period 1920–2080. We compare K–T climate types from the Medieval Climate Anomaly (MCA) (950–1250) with the Little Ice Age (LIA) (1550–1850), from present day (PD) (1971–2000) with the last millennium (LM) (850–1850), and from the future (2050–2080) with the LM in order to place anthropogenic changes in the context of changes due to natural forcings occurring during the last millennium. For CESM-LME, we focused on the simulations with all forcings, though the impacts of individual forcings (e.g., solar activities, volcanic eruptions, greenhouse gases, aerosols and land use changes) were also analyzed. We found that the climate types changed slightly between the MCA and the LIA due to weak changes in temperature and precipitation. The climate type changes in PD relative to the last millennium have been largely driven by greenhouse gas-induced warming, but anthropogenic aerosols have also played an important role on regional scales. At the end of the twenty-first century, the anthropogenic forcing has a much greater effect on climate types than the PD. Following the reduction of aerosol emissions, the impact of greenhouse gases will further promote global warming in the future. Compared to precipitation, changes in climate types are dominated by greenhouse gas-induced warming. The large shift in climate types by the end of this century suggests possible wide-spread redistribution of surface vegetation and a significant change in species distributions.

In this paper, introducing new remote sensing and geographic information technology to solve the problem of data collection and analysis, this makes the study of ecological risk assessment very quick and accurate. Taking the Shan Xin mining area of the tin mine in Lengshuijiang of Hunan Province as the research object, using the remote sensing image data of three periods in 2005, 2010 and 2015, the remote sensing image is classified carefully and the landscape classification map of the mining area is obtained. The ecological risk index is introduced and the ecological risk values are sampled and interpolated on the ArcGIS platform. The ecological risk spatial distribution map based on the landscape pattern index was obtained. The ecological risk was divided into 5 levels by using the Jenks natural classification method, and each ecological risk grade area was counted. The research results show that: from year 2005 to year 2010, landscape ecological risk trend of the mining area is growing up; the trend rising area of landscape ecological risk is mainly in the southwest and northeast of the Shan Xin mining field; the area of higher and high ecological risk is increasing year by year; and the trend of dispersed development in space is obvious; the development trend of ecological risk in the mining area is rapidly increasing; in 2010 - 2015, the higher and high ecological risk area decrease slightly with the increasing of area of grassland and residential low vulnerability of landscape types; the ecological risk area showed a slow decreasing trend. The research results provide an objective reference for decision making of ecological environment governance.

In recent years, earth-abundant transition metal catalysts have been used to make great achievements on homogenous catalysis, including the field of enantioselective hydrofunctionalization of alkenes. Minimally functionalized alkenes are a class of challenging substrates for the catalytic asymmetric hydrofunctionalization reactions. This review summarizes the advances of the highly enantioselective (≥90% ee) hydrofunctionalization reactions of minimally functionalized alkenes using earth-abundant transition metals (iron, cobalt, nickel, copper, titanium and zirconium) as catalysts.

A long-term perspective on the spatial variation of the northern boundary of the East Asian summer monsoon (EASM) and the related physical mechanisms is important for understanding past climate change in Asia and for predicting future changes. However, most of the meteorological definitions of the EASM northern boundary do not correspond well to the actual geographical environment, which is problematic for paleoclimatic research. Here, we use monthly CMAP and GPCP precipitation data to define a new EASM northern boundary index by using the concept of the global monsoon, which is readily applicable to paleoclimatic research. The results show that the distribution of the 2 mm day−1 precipitation isoline (i.e., 300 mm precipitation) has a good relationship with the spatial distribution of modern land cover types, the transitional climate zone and the potential natural vegetation types, in China. The locations of the precipitation isolines also correspond well to the locations of major shifts in wind direction. These results suggest that the 2 mm day−1 isoline has a clear physical significance since the climatic, ecological, and geographical boundary can be used as the northern boundary index of the EASM (which we call the climatological northern boundary index). The index depicts the northeast-southwest orientation of the climatological (1981−2010) EASM northern boundary, along the eastern part of the Qilian Mountains-southern foothills of the Helan Mountains-Daqing Mountains-western margin of the Greater Khingan Range, from west to east across Northwest and Northeast China. The interannual change of the EASM northern boundary from 1980 to 2015 covers the central part of Gansu, the northern part of Ningxia, the eastern part of Inner Mongolia and the northeastern region in China. It can extend northward to the border between China and Mongolia and retreat southward to Shangdong-central Henan. There is a 200−700 km fluctuation range of the interannual EASM northern boundaries around the locations of the climatological northern boundary. In addition, the spatial variation of the interannual EASM northern boundaries gradually increases from west to east, whereas the trend of north-south fluctuations maintains a roughly consistent location in different regions.

Controlling the crystallization dynamics is one key in optimizing the performance of perovskite solar cells (PSCs). The present study provides a simple approach using a low temperature stable-transition-film (STF) to prepare highly-dense and pinhole-free CsPbIBr 2 thin film with high crystalline quality, as well as a new structural design (FTO/NiO x /CsPbIBr 2 /MoO x /Au) of all-inorganic perovskite solar cells toward long-term thermal stability. For the first time, we demonstrate that MoO x can independently serve as an outstanding cathode buffer layer on an inorganic perovskite layer. The lower work-function MoO x with ultra-thin thickness (4 nm) leads to decreases of the Schottky barrier, the contact resistance and the interface trap-state density. This increases the power conversion efficiency (PCE) of all-inorganic planar PSCs from 1.3% to 5.52%. Inspiringly, the FTO/NiO x /CsPbIBr 2 /MoO x /Au all-inorganic PSCs were demonstrated to possess excellent long-term thermal stability at high temperatures up to 160 °C.

Although the pattern of Holocene temperature variations in central Asia is complex, it is clear that temperature played a fundamental role in influencing humidity conditions and regional human activity. We reconstructed temperature changes using Pediastrum species data, verified by clumped isotopes (Δ47), in the carbonates of sediment cores recovered from Bosten Lake in Xinjiang Province, northwestern China. Combined with archaeological data, the results indicate an unusually warm climatic interval that peaked at ∼4.7–4.3 kyr and promoted human occupation of the Altai Mountains. The climate cooled during 4.2–4.1 kyr and 3.6–3.5 kyr, as indicated by the decrease or absence of Pediastrum simplex. These cold events may have triggered the southward human migration out of the Altai region, resulting in the widespread distribution of archaeological sites at lower latitudes, in the Tienshan Mountains, and in the desert-oasis areas of the Tarim Basin in southern Xinjiang. Our data support the notion that a series of cultural transitions across the monsoonal Loess Plateau and Tibetan Plateau of China may have been linked to temperature changes during the middle to late Holocene.

Pediastrum Meyen is often well preserved in lake sediments and its abundance and species composition are very sensitive to changes in the aquatic environment. Previous studies have shown that changes in the composition or abundance of Pediastrum species have great potential for studying paleoenvironmental evolution. However, until now, very few studies have explored the environmental significance of Pediastrum and used it as a paleoclimatic or paleoenvironmental indicator. In this study, we investigated the occurrence of Pediastrum in 26 natural lakes and 17 reservoirs, with varying hydro-chemical and climatic gradients, in China and western Mongolia. 25 Pediastrum taxa (including species and varieties) were found in the surface sediments of 36 different water bodies, and the spatial distribution characteristics of Pediastrum species and the environmental factors determining the community composition were identified using both Canonical Correspondence Analysis (CCA) and extended Huisman-Olff-Fresco (eHOF) methods. The results demonstrate that mean annual temperature is the most significant environmental variable influencing modern Pediastrum species composition and abundance. Water salinity and trophic status are probably secondary factors that are responsible for the variations in the abundance of Pediastrum species, and they cannot survive in water bodies with total dissolved solids (TDS) higher than ~ 2–3 g L−1. Overall, our results indicate that Pediastrum assemblages have great potential for reconstructing environmental variables in the past, and therefore that they can be used for environmental monitoring in global warming research.