Influence of O-O formation pathways and charge transfer mediator on lipid bilayer membrane-like photoanodes for water oxidation

Inspired by the function of crucial components in photosystemⅡ(PSⅡ),electrochemical and dyesensitized photoelectrochemical(DSPEC)water oxidation devices were constructed by the selfassembly of well-designed amphipathic Ru(bda)-based catalysts(bda=2,2'-bipyrdine-6,6'-dicarbonoxyl acid)and aliphatic chain decorated electrode surfaces,forming lipid bilayer membrane(LBM)-like structures.The Ru(bda)catalysts on electrode-supported LBM films demonstrated remarkable water oxidation performance with different O-O formation mechanisms.However,compared to the slow charge transfer process,the O-O formation pathways did not determine the PEC water oxidation efficiency of the dyesensitized photoanodes,and the different reaction rates for similar catalysts with different catalytic paths did not determine the PEC performance of the DSPECs.Instead,charge transfer plays a decisive role in the PEC water oxidation rate.When an indolo[3,2-b]carbazole derivative was introduced between the Ru(bda)catalysts and aliphatic chain-modified photosensitizer in LBM films,serving as a charge transfer mediator for the tyrosine-histidine pair in PSⅡ,the PEC water oxidation performance of the corresponding photoanodes was dramatically enhanced.

The changes in soil organic carbon stock and quality across a subalpine forest successional series

Soil organic carbon(SOC)affects the function of terrestrial ecosystem and plays a vital role in global carbon cycle.Yet,large uncertainty still existed regarding the changes in SOC stock and quality with forest succession.Here,the stock and quality of SOC at 1-m soil profile were investigated across a subalpine forest series,including shrub,deciduous broad-leaved forest,broadleaf-conifer mixed forest,middle-age coniferous forest and mature coniferous forest,which located at southeast of Tibetan Plateau.The results showed that SOC stock ranged from 9.8 to29.9 kg·m^(-2),and exhibited a hump-shaped response pattern across the forest successional series.The highest and lowest SOC stock was observed in the mixed forest and shrub forest,respectively.The SOC stock had no significant relationships with soil temperature and litter stock,but was positively correlated with wood debris stock.Meanwhile,the average percentages of polysaccharides,lignins,aromatics and aliphatics based on FTIR spectroscopy were 79.89%,0.94%,18.87%and 0.29%,respectively.Furthermore,the percentage of polysaccharides exhibited an increasing pattern across the forest successional series except for the sudden decreasing in the mixed forest,while the proportions of lignins,aromatics and aliphatics exhibited a decreasing pattern across the forest successional series except for the sudden increasing in the mixed forest.Consequently,the humification indices(HIs)were highest in the mixed forest compared to the other four successional stages,which means that the SOC quality in mixed forest was worse than other successional stages.In addition,the SOC stock,recalcitrant fractions and HIs decreased with increasing soil depth,while the polysaccharides exhibited an increasing pattern.These findings demonstrate that the mixed forest had higher SOC stock and worse SOC quality than other successional stages.The high proportion of SOC stock(66%at depth of 20-100 cm)and better SOC quality(lower HIs)indicate that deep soil have tremendous potential to store SOC and needs more attention under global chan ge.

Facilitators and barriers to parent-child communication in pediatric palliative care:An integrative review

Objectives:This study aimed to identify facilitators and barriers to parent-child communication in pediatric palliative care,providing insights for medical professionals developing targeted interventions to enhance parent-child communication and improve its effectiveness.Methods:Whittemore and Knafl’s integrative review method was employed to guide a systematic search for literature in six databases(Medline,Embase,CINAHL Complete,PsycINFO,Web of Science,and Cochrane Library).Peer-reviewer articles published in the English language from inception to December 2023.All of the identified studies were screened,extracted,and analyzed independently by two researchers.Results:Twenty-four articles were included.Thefindings of the relevant studies were analyzed using thematic analysis.Four themes were identified as facilitators:legacy-making,resilience training programs,guidance from the healthcare team,and positive communication.Seven themes were identified as barriers:denial,being unprepared and evasive,mutual protection,being overwhelmed by painful emotions and overloaded with information,incorrect views of medical professionals and parents,negative communication,and cultural context.Conclusions:Parents and professionals should avoid myths about protecting the child and encourage open communication that respects the child’s wishes.The specialized pediatric palliative care team should carefully monitor parent-child communication,determine if any obstacles exist,and design more interventions to enhance it.

Polarization control of above-threshold ionization spectrum in elliptically polarized two-color laser fields

We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain theory.It is found that the angular-resolved ATI spectrum is sensitive to ellipticities of two lasers and emitted angles of the photoelectron.Particularly for the photon energy of the highfrequency laser more than atomic ionization potential,the width of plateau tends to a constant with increasing ellipticity of fundamental field,the dip structure disappears with increasing ellipticity of the high-frequency field.With the help of the quantum channel analysis,it is shown that the angular distribution depends mainly on the ellipticity of high-frequency field in the case that its frequency is high.Moreover,one can see that the maximal and minimal energies in quantum numerical results are in good agreement with the classical prediction.Our investigation may provide theoretical support for experimental research on polarization control of ionization in elliptically polarized two-color laser fields.

Preface to the Special Topic on Ocean, Sea Ice and Northern Hemisphere Climate:In Remembrance of Professor Yongqi GAO's Key Contributions

This special issue commemorates the life work of Prof. Yongqi GAO who passed away in July 2021, his time cut short by illness. He had many great achievements, but still much more to contribute. The seven articles in this special issue are from research areas where he contributed, and they illustrate how his close colleagues are continuing his work.

Factors influencing willingness to participate in ophthalmic clinical trials and strategies for effective recruitment

AIM:To explore the factors influencing individuals’willingness to participate in ophthalmic clinical trials.METHODS:A questionnaire survey was conducted from January to April 2021 among patients and their family members at Zhongshan Ophthalmic Center,Sun Yat-sen University,in Guangzhou,China.The survey gathered data on respondents’willingness,demographic and socioeconomic profiles,as well as their reasons and concerns regarding engagement in clinical trials.RESULTS:Of the 1078 residents surveyed(mean age 31.2±13.1y;65.8%females)in Guangzhou,749(69.5%)expressed a willingness to participate in future ophthalmic clinical trials.Specific characteristics associated with greater willingness included a younger age,lower annual income,higher education,prior participation experience,previous ophthalmic treatment,and a better understanding of clinical trials.With the exception of age,these characteristics were significantly linked to a higher willingness.The primary barrier to participation,expressed by 64.8%of those willing and 54.4%of those unwilling,was“Uncertain efficacy”.In terms of motivations,the willing group ranked“Better therapeutic benefits”(35.0%),“Professional monitoring”(34.3%),and“Trust in healthcare professionals”(33.1%)as their top three reasons,whereas the unwilling participants indicated“Full comprehension of the protocol”(46.2%)as the key facilitator.CONCLUSION:This study reveals a substantial willingness to participate in ophthalmic clinical trials and demonstrates the predictive role of demographic and socioeconomic factors.Variations in motivators and concerns between willing and unwilling participants highlight the significance of tailored recruitment strategies.Importantly,the need for and trust in healthcare professionals stand out as powerful motivations,underscoring the importance of enhancing physician-patient relationships,adopting patient-centered communication approaches,and addressing individualized needs to improve accrual rates.

Personalized assessment and training of neurosurgical skills in virtual reality:An interpretable machine learning approach

Background Virtual reality technology has been widely used in surgical simulators,providing new opportunities for assessing and training surgical skills.Machine learning algorithms are commonly used to analyze and evaluate the performance of participants.However,their interpretability limits the personalization of the training for individual participants.Methods Seventy-nine participants were recruited and divided into three groups based on their skill level in intracranial tumor resection.Data on the use of surgical tools were collected using a surgical simulator.Feature selection was performed using the Minimum Redundancy Maximum Relevance and SVM-RFE algorithms to obtain the final metrics for training the machine learning model.Five machine learning algorithms were trained to predict the skill level,and the support vector machine performed the best,with an accuracy of 92.41%and Area Under Curve value of 0.98253.The machine learning model was interpreted using Shapley values to identify the important factors contributing to the skill level of each participant.Results This study demonstrates the effectiveness of machine learning in differentiating the evaluation and training of virtual reality neurosurgical performances.The use of Shapley values enables targeted training by identifying deficiencies in individual skills.Conclusions This study provides insights into the use of machine learning for personalized training in virtual reality neurosurgery.The interpretability of the machine learning models enables the development of individualized training programs.In addition,this study highlighted the potential of explanatory models in training external skills.

Mediating function of heart failure in the causal relationship between diastolic blood pressure and hypertensive renal disease with renal failure:a mediated Mendelian randomization study

Objective:To study the causality relationship between diastolic blood pressure(DBP)and hypertensive renal disease with renal failure(HRDRF)and the mediating role of hear t failure(HF)in the causality relationship by network Mendelian randomization(MR).Methods:Genome-wide analysis of DBP,HRDRF,and HF was downloaded from the public database(Genome-Wide Analysis Study[GWAS])and was used to analyze the results and to conduct mediated MR analysis.Results:Analysis showed that DBP was positively correlated with HRDRF(OR=1.0002,95%CI:1.0001–1.0003,P=1.8076e-05)and DBP was positively correlated with HF(OR=1.0295,95%CI:1.0221–1.0370,P=2.5292e-15).HF and HRDRF had a positive causal effect(OR=1.0001,95%CI:1.0000–1.0001,P=0.0152).Mediation analysis showed that the contribution ratio of HF to the combined effect of DBP and HRDRF was 24.69%.Conclusions:DBP can increase the risk of renal disease with renal failure,and HF may play an impor tant role in mediating this causal relationship.

An Efficient Numerical Scheme for Biological Models in the Frame of Bernoulli Wavelets

This article considers three types of biological systems:the dengue fever disease model,the COVID-19 virus model,and the transmission of Tuberculosis model.The new technique of creating the integration matrix for the Bernoulli wavelets is applied.Also,the novel method proposed in this paper is called the Bernoulli wavelet collocation scheme(BWCM).All three models are in the form system of coupled ordinary differential equations without an exact solution.These systems are converted into a system of algebraic equations using the Bernoulli wavelet collocation scheme.The numerical wave distributions of these governing models are obtained by solving the algebraic equations via the Newton-Raphson method.The results obtained from the developed strategy are compared to several schemes such as the Runge Kutta method,and ND solver in mathematical software.The convergence analyses are discussed through theorems.The newly implemented Bernoulli wavelet method improves the accuracy and converges when it is compared with the existing methods in the literature.

Anti-inflammatory effects of amarogentin on 2,4-dinitrochlorobenzene-induced atopic dermatitis-like mice and in HaCat cells

Background:Amarogentin(AMA)is a secoiridoid glycoside extracted from Swertia and Gentiana roots and exhibits many biological effects such as antioxidative,antiinflammatory,and antitumor activities.Atopic dermatitis(AD)is a chronic inflammatory skin disease caused by disorders in the regulation of multiple inflammatory cytokines.No effective cure has been found for AD now.Methods:We constructed the HaCat and splenocyte model and tested the inhibitory effect of AMA on IL-4,IL-6,and IL-13 secretions using enzyme-linked immunosorbent assay(ELISA).The AD mouse model was constructed and treated with AMA,the severity of skin lesions was observed,epidermal tissue was collected,and epidermal thickness and mast cell infiltration were observed using hematoxylin and eosin and toluidine blue staining,respectively.The expression of kallikrein-related peptidase 7(KLK7)and filaggrin(FLG)was detected using immunostaining and Western blot analysis.The mRNA expression of KLK7 and FLG was detected using quantitative polymerase chain reaction(qPCR).Blood immunoglobulin E(IgE)secretion was detected.Results:AMA inhibited IL-6 secreted by tumor necrosis factor(TNF)-α-induced HaCaT cells and reduced IL-4 and IL-13 secreted by phytohemagglutinin(PHA)-induced primary cells in the mice spleen.It was found that the treatment of AMA with 2,4-din itrochlorobenzene-induced AD-like mice could promote the recovery of dermatitis,reduce the score of dermatitis severity and the scratching frequency,treat the skin lesions,reduce the epidermal thickness,decrease the infiltration of mast cells,reduce the IgE level in serum,decrease the expression levels of AD-related cytokines,increase protein and mRNA expression of FLG,and reduce the protein and mRNA expression of KLK7 in the skin tissues of AD-like mice.Conclusion:In conclusion,AMA inhibits inflammatory response at the cellular level,and AMA reduces the validation response of specific dermatitis mice,relieves pruritus,and repairs the damaged skin barrier.

Acinous cell AR42J-derived exosome miR125b-5p promotes acute pancreatitis exacerbation by inhibiting M2 macrophage polarization via PI3K/AKT signaling pathway

BACKGROUND The incidence rate of acute pancreatitis(AP), which is a pathophysiological process with complex etiology, is increasing globally. miR-125b-5p, a bidirectional regulatory miRNA, is speculated to exhibit anti-tumor activity. However,exosome-derived miR-125b-5p in AP has not been reported.AIM To elucidate the molecular mechanism of exosome-derived miR-125b-5p promoting AP exacerbation from the perspective of the interaction between immune cells and acinar cells.METHODS Exosomes derived from AR42J cells were isolated and extracted in active and inactive states by an exosome extraction kit, and were verified via transmission electron microscopy, nanoparticle tracking analysis, and western blotting. RNA sequencing assay technology was used to screen differentially expressed miRNAs in active and inactive AR42J cell lines, and bioinformatics analysis was used to predict downstream target genes of miR-125b-5p. The expression level of miR-125b-5p and insulin-like growth factor 2(IGF2) in the activated AR42J cell line and AP pancreatic tissue were detected by quantitative real-time polymerase chain reaction and western blots. The changes in the pancreatic inflammatory response in a rat AP model were detected by histopathological methods. Western Blot was used to detect the expression of IGF2, PI3K/AKT signaling pathway proteins, and apoptosis and necrosis related proteins.RESULTS miR-125b-5p expression was upregulated in the activated AR42J cell line and AP pancreatic tissue,while that of IGF2 was downregulated. In vitro experiments confirmed that miR-125b-5p could promote the death of activated AR42J cells by inducing cell cycle arrest and apoptosis. In addition,miR-125b-5p was found to act on macrophages to promote M1 type polarization and inhibit M2type polarization, resulting in a massive release of inflammatory factors and reactive oxygen species accumulation. Further research found that miR-125b-5p could inhibit the expression of IGF2 in the PI3K/AKT signaling pathway. Additionally, in vivo experiments revealed that miR-125b-5p can promote the progression of AP in a rat model.CONCLUSION miR-125b-5p acts on IGF2 in the PI3K/AKT signaling pathway and promotes M1 type polarization and inhibits M2 type polarization of macrophage by inhibiting IGF2 expression, resulting in a large release of pro-inflammatory factors and an inflammatory cascade amplification effect, thus aggravating AP.

Pregnenolone 16α-carbonitrile negatively regulates hippocampal cytochrome P450 enzymes and ameliorates phenytoin-induced hippocampal neurotoxicity

The central nervous system is susceptible to the modulation of various neurophysiological processes by the cytochrome P450 enzyme(CYP),which plays a crucial role in the metabolism of neurosteroids.The antiepileptic drug phenytoin(PHT)has been observed to induce neuronal side effects in patients,which could be attributed to its induction of CYP expression and testosterone(TES)metabolism in the hippocampus.While pregnane X receptor(PXR)is widely known for its regulatory function of CYPs in the liver,we have discovered that the treatment of mice with pregnenolone 16α-carbonitrile(PCN),a PXR agonist,has differential effects on CYP expression in the liver and hippocampus.Specifically,the PCN treatment resulted in the induction of cytochrome P450,family 3,subfamily a,polypeptide 11(CYP3A11),and CYP2B10 expression in the liver,while suppressing their expression in the hippocampus.Functionally,the PCN treatment protected mice from PHT-induced hippocampal nerve injury,which was accompanied by the inhibition of TES metabolism in the hippocampus.Mechanistically,we found that the inhibition of hippocampal CYP expression and attenuation of PHT-induced neurotoxicity by PCN were glucocorticoid receptor dependent,rather than PXR independent,as demonstrated by genetic and pharmacological models.In conclusion,our study provides evidence that PCN can negatively regulate hippocampal CYP expression and attenuate PHT-induced hippocampal neurotoxicity independently of PXR.Our findings suggest that glucocorticoids may be a potential therapeutic strategy for managing the neuronal side effects of PHT.

A comparative single-pulse shock tube experiment and kinetic modeling study on pyrolysis of cyclohexane,methylcyclohexane and ethylcyclohexane

The pyrolysis of cyclohexane,methylcyclohexane,and ethylcyclohexane have been studied behind reflected shock waves at pressures of 5 and10 bar and at temperatures of 930-1550 K for 0.05%fuel diluted by Argon.A single-pulse shock tube(SPST)is used to perform the pyrolysis experiments at reaction times varying from 1.65 to 1.74 ms.Major products are obtained and quantified using gas chromatography analysis.A flame ionization detector and a thermal conductivity detector are used for species identification and quantification.Kinetic modeling has been performed using several detailed and lumped chemical kinetic mechanisms.Differences in modeling results among the kinetic models are described.Reaction path analysis and sensitivity analysis are performed to determine the important reactions controlling fuel pyrolysis and their influence on the predicted concentrations of reactant and product species profiles.The present work provides new fundamental knowledge in understating pyrolysis characteristics of cyclohexane compounds and additional data set for detailed kinetic mechanism development.

Eff ect of prescribed burning on the small-scale spatial heterogeneity of soil microbial biomass in Pinus koraiensis and Quercus mongolica forests of China

Prescribed burning can alter soil microbial activity and spatially redistribute soil nutrient elements.However,no systematic,in-depth studies have investigated the impact of prescribed burning on the spatial patterns of soil microbial biomass in temperate forest ecosystems in Northeast China.The present study investigated the impacts of prescribed burning on the small-scale spatial heterogeneity of microbial biomass carbon(MBC)and microbial biomass nitrogen(MBN)in the upper(0–10 cm)and lower(10–20 cm)soil layers in Pinus koraiensis and Quercus mongolica forests and explored the factors that infl uence spatial variations of these variables after prescribed burning.Our results showed that,MBC declined by approximately 30%in the 10–20 cm soil layer in the Q.mongolica forest,where there were no signifi cant eff ects on the soil MBC and MBN contents of the P.koraiensis forest(p>0.05)after prescribed burning.Compared to the MBC of the Q.mongolica forest before the prescribed burn,MBC spatial dependence in the upper and lower soil layers was approximately 7%and 2%higher,respectively.After the prescribed burn,MBN spatial dependence in the upper and lower soil layers in the P.koraiensis forest was approximately 1%and 13%lower,respectively,than that before the burn,and the MBC spatial variability in the 0–10 cm soil layer in the two forest types was explained by the soil moisture content(SMC),whereas the MBN spatial variability in the 0–10 cm soil layer in the two forests was explained by the soil pH and nitrate nitrogen(NO_(3)^(–)-N),respectively.In the lower soil layer(10–20 cm)of the Q.mongolica forest,elevation and ammonium nitrogen(NH 4+-N)were the main factors aff ecting the spatial variability of MBC and MBN,respectively.In the 10–20 cm soil layer of the P.koraiensis forest,NO_(3)^(–)-N and slope were the main factors aff ecting the spatial variability of MBC and MBN,respectively,after the burn.The spatial distributions of MBC and MBN in the two forests were largely structured with higher spatial autocorrelation(relative structural variance C/[C 0+C]>0.75).However,the factors infl uencing the spatial variability of MBC and MBN in the two forest types were not consistent between the upper and lower soil layers with prescribed burning.These fi ndings have important implications for developing sustainable management and conservation policies for forest ecosystems.

A weighted block cooperative sparse representation algorithm based on visual saliency dictionary

Unconstrained face images are interfered by many factors such as illumination,posture,expression,occlusion,age,accessories and so on,resulting in the randomness of the noise pollution implied in the original samples.In order to improve the sample quality,a weighted block cooperative sparse representation algorithm is proposed based on visual saliency dictionary.First,the algorithm uses the biological visual attention mechanism to quickly and accurately obtain the face salient target and constructs the visual salient dictionary.Then,a block cooperation framework is presented to perform sparse coding for different local structures of human face,and the weighted regular term is introduced in the sparse representation process to enhance the identification of information hidden in the coding coefficients.Finally,by synthesising the sparse representation results of all visual salient block dictionaries,the global coding residual is obtained and the class label is given.The experimental results on four databases,that is,AR,extended Yale B,LFW and PubFig,indicate that the combination of visual saliency dictionary,block cooperative sparse representation and weighted constraint coding can effectively enhance the accuracy of sparse representation of the samples to be tested and improve the performance of unconstrained face recognition.

Application of Multi-Attribute Crossplots to Tight Gas in X Area, Western China

The gas-bearing reservoir in X area is mainly the tight sandstone reservoir characterized by low porosity and permeability, frequently lateral variation and poor connectivity of single sand. The previous research results reveal that the general seismic attributes analysis cannot meet the requirement of fluid identification. This is because the relationship between seismic attributes and their implication is uncertain and ambiguous, which decreases the precision of both reservoir prediction and fluid identification. To overcome the problem, multi-attribute crossplot technology is proposed from the mathematical statistical point of view rather than the correspondence between the seismic attributes and their geological implication. In this method, the wells which have the same statistical law are classified firstly, and then all the interest wells are retained while the wells beyond the statistical law are eliminated, and the seismic attributes sensitive to the same types of eliminated wells are optimized and used to generate crossplots. The nonzero area of their crossplots results just predicts the potential distribution. The discontinuity of subsurface geological conditions results in the non-continuous shape and the seismic bin lead to the mosaic form. The optimization of sensitive attributes relative to the same types of wells is independent from each other, and thus the order of attributes in crossplots does not affect the final prediction results. This method is based on the statistical theory and suitable for the areas such as the study area abundant of lots of well data. Application to X area proves the effectiveness of this method and predicts plane distribution about different types of gas production. Due to the effect of faults and other geological factors, the partition prediction results using multi-attribute crossplots reach 95% of coincidence which is obviously and far higher than the results of the whole area. The final prediction results show that the potential areas with medium and high gas production are mainly concentrated in the northern part of the study area, where lots of development research will be strengthened.

一体化加力燃烧室燃油自燃特性研究

为探索一体化加力燃烧室内发生自燃现象的规律,以一体化支板中的燃油喷射系统为研究对象,采用高速摄影法拍摄了燃油在高温来流条件下的自燃火焰,重点分析了一体化加力燃烧室来流温度、来流速度、余气系数、燃油喷嘴类型等因素对于燃油自燃特性的影响规律。结果表明:提高加力燃烧室来流温度使得燃油更容易发生自燃,当来流温度超过1 200 K时所有工况下燃油都可以发生自燃;提高加力燃烧室来流速度有利于抑制自燃,使得燃油自燃延迟距离增大;贫油情况下燃油颗粒可以从环境中吸收更多的热量,自燃延迟距离减小;雾化效果好的锥形雾化喷嘴容易发生自燃,雾化效果差的直射式喷嘴相对稳定。研究结果为一体化加力燃烧室的供油系统和点火系统的设计提供初步的参考价值。

Mitophagy in neurodegenerative disease pathogenesis

Mitochondria are critical cellular energy resources and are central to the life of the neuron.Mitophagy selectively clears damaged or dysfunctional mitochondria through autophagic machinery to maintain mitochondrial quality control and homeostasis.Mature neurons are postmitotic and consume substantial energy,thus require highly efficient mitophagy pathways to turn over damaged or dysfunctional mitochondria.Recent evidence indicates that mitophagy is pivotal to the pathogenesis of neurological diseases.However,more work is needed to study mitophagy pathway components as potential therapeutic targets.In this review,we briefly discuss the characteristics of nonselective autophagy and selective autophagy,including ERphagy,aggrephagy,and mitophagy.We then introduce the mechanisms of Parkin-dependent and Parkin-independent mitophagy pathways under physiological conditions.Next,we summarize the diverse repertoire of mitochondrial membrane receptors and phospholipids that mediate mitophagy.Importantly,we review the critical role of mitophagy in the pathogenesis of neurodegenerative diseases including Alzheimer’s disease,Parkinson’s disease,and amyotrophic lateral sclerosis.Last,we discuss recent studies considering mitophagy as a potential therapeutic target for treating neurodegenerative diseases.Together,our review may provide novel views to better understand the roles of mitophagy in neurodegenerative disease pathogenesis.

Projecting Wintertime Newly Formed Arctic Sea Ice through Weighting CMIP6 Model Performance and Independence

Precipitous Arctic sea-ice decline and the corresponding increase in Arctic open-water areas in summer months give more space for sea-ice growth in the subsequent cold seasons. Compared to the decline of the entire Arctic multiyear sea ice,changes in newly formed sea ice indicate more thermodynamic and dynamic information on Arctic atmosphere–ocean–ice interaction and northern mid–high latitude atmospheric teleconnections. Here, we use a large multimodel ensemble from phase 6 of the Coupled Model Intercomparison Project(CMIP6) to investigate future changes in wintertime newly formed Arctic sea ice. The commonly used model-democracy approach that gives equal weight to each model essentially assumes that all models are independent and equally plausible, which contradicts with the fact that there are large interdependencies in the ensemble and discrepancies in models' performances in reproducing observations. Therefore, instead of using the arithmetic mean of well-performing models or all available models for projections like in previous studies, we employ a newly developed model weighting scheme that weights all models in the ensemble with consideration of their performance and independence to provide more reliable projections. Model democracy leads to evident bias and large intermodel spread in CMIP6 projections of newly formed Arctic sea ice. However, we show that both the bias and the intermodel spread can be effectively reduced by the weighting scheme. Projections from the weighted models indicate that wintertime newly formed Arctic sea ice is likely to increase dramatically until the middle of this century regardless of the emissions scenario.Thereafter, it may decrease(or remain stable) if the Arctic warming crosses a threshold(or is extensively constrained).

Arctic Sea Ice Variations in the First Half of the 20th Century:A New Reconstruction Based on Hydrometeorological Data

The shrinking Arctic sea-ice area(SIA) in recent decades is a striking manifestation of the ongoing climate change.Variations of the Arctic sea ice have been continuously observed by satellites since 1979, relatively well monitored since the 1950s, but are highly uncertain in the earlier period due to a lack of observations. Several reconstructions of the historical gridded sea-ice concentration(SIC) data were recently presented based on synthesized regional sea-ice observations or by applying a hybrid model–empirical approach. Here, we present an SIC reconstruction for the period1901–2019 based on established co-variability between SIC and surface air temperature, sea surface temperature, and sea level pressure patterns. The reconstructed sea-ice data for March and September are compared to the frequently used Had ISST1.1 and SIBT1850 datasets. Our reconstruction shows a large decrease in SIA from the 1920 to 1940 concurrent with the Early 20th Century Warming event in the Arctic. Such a negative SIA anomaly is absent in Had ISST1.1 data. The amplitude of the SIA anomaly reaches about 0.8 mln km^(2) in March and 1.5 mln km^(2) in September. The anomaly is about three times stronger than that in the SIBT1850 dataset. The larger decrease in SIA in September is largely due to the stronger SIC reduction in the western sector of the Arctic Ocean in the 70°–80°N latitudinal zone. Our reconstruction provides gridded monthly data that can be used as boundary conditions for atmospheric reanalyses and model experiments to study the Arctic climate for the first half of the 20th century.