Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano‑Aerogel via Abundant Nano‑Sized Cavities and Attenuation Interfaces

Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.

Highly Thermally Conductive and Structurally Ultra‑Stable Graphitic Films with Seamless Heterointerfaces for Extreme Thermal Management

Highly thermally conductive graphitic film(GF)materials have become a competitive solution for the thermal management of high-power electronic devices.However,their catastrophic structural failure under extreme alternating thermal/cold shock poses a significant challenge to reliability and safety.Here,we present the first investigation into the structural failure mechanism of GF during cyclic liquid nitrogen shocks(LNS),which reveals a bubbling process characterized by“permeation-diffusion-deformation”phenomenon.To overcome this long-standing structural weakness,a novel metal-nanoarmor strategy is proposed to construct a Cu-modified graphitic film(GF@Cu)with seamless heterointerface.This well-designed interface ensures superior structural stability for GF@Cu after hundreds of LNS cycles from 77 to 300 K.Moreover,GF@Cu maintains high thermal conductivity up to 1088 W m^(−1)K^(−1)with degradation of less than 5%even after 150 LNS cycles,superior to that of pure GF(50%degradation).Our work not only offers an opportunity to improve the robustness of graphitic films by the rational structural design but also facilitates the applications of thermally conductive carbon-based materials for future extreme thermal management in complex aerospace electronics.

Correction:Monodomain Liquid Crystals of Two‑Dimensional Sheets by Boundary‑Free Sheargraphy

In this article Florian Puchtler at affiliation‘University of Bayreuth’,Josef Breu at affiliation‘University of Bayreuth’,and Ziliang Wu at affiliation‘Zhejiang University’was missing from the author Min Cao,Senping Liu,Qingli Zhu,Ya Wang,Jingyu Ma,Zeshen Li,Dan Chang,Enhui Zhu,Xin Ming,Florian Puchtler,Josef Breu,Ziliang Wu,Yingjun Liu,Yanqiu Jiang,Zhen Xu,Chao Gao list.

维持小胶质细胞稳态需要NG2胶质细胞

小胶质细胞在中枢神经系统的健康和疾病状态中起着至关重要的作用。小胶质细胞稳态的丧失是脑衰老和神经变性的关键特征。然而,维持小胶质细胞独特细胞状态的机制尚不清楚。本研究显示NG2胶质细胞,也称为少突胶质细胞前体细胞,对于维持小胶质细胞稳态至关重要。我们开发了一种高效的、选择性的NG2胶质细胞耗竭方法,该方法在培养的脑切片中使用血小板衍生的生长因子(PDGF)信号通路的小分子抑制剂。我们发现,NG2胶质细胞的丧失消除了稳态的小胶质细胞特征,而并不影响与疾病相关的小胶质细胞特征。通过遗传消耗NG2胶质细胞或条件性地抑制NG2胶质细胞PDGF信号,我们在成年小鼠脑中也在体观察到了类似的发现。这些数据表明,NG2胶质细胞对与脑衰老和神经退行性疾病相关的小胶质细胞状态起着至关重要的作用。此外,本研究结果为研究NG2胶质细胞功能提供了一个强大、便捷且具选择性的研究手段。

A Mini Review on Nanocarbon-Based 1D Macroscopic Fibers:Assembly Strategies and Mechanical Properties

Nanocarbon-based materials, such as carbon nanotubes(CNTs) and graphene have been attached much attention by scientific and industrial community. As two representative nanocarbon materials, one-dimensional CNTs and twodimensional graphene both possess remarkable mechanical properties. In the past years, a large amount of work have been done by using CNTs or graphene as building blocks for constructing novel, macroscopic, mechanically strong fibrous materials. In this review, we summarize the assembly approaches of CNT-based fibers and graphene-based fibers in chronological order, respectively. The mechanical performances of these fibrous materials are compared, and the critical influences on the mechanical properties are discussed. Personal perspectives on the fabrication methods of CNT-and graphene-based fibers are further presented.

Monodomain Liquid Crystals of Two-Dimensional Sheets by Boundary-Free Sheargraphy

Eliminating topological defects to achieve monodomain liquid crystals is highly significant for the fundamental studies of soft matter and building long-range ordered materials.However,liquid crystals are metastable and sensitive to external stimuli,such as flow,confinement,and electromagnetic fields,which cause their intrinsic polycrystallinity and topological defects.Here,we achieve the monodomain liquid crystals of graphene oxide over 30 cm through boundary-free sheargraphy.The obtained monodomain liquid crystals exhibit large-area uniform alignment of sheets,which has the same optical polarized angle and intensity.The monodomain liquid crystals provide bidirectionally ordered skeletons,which can be applied as lightweight thermal management materials with bidirectionally high thermal and electrical conductivity.Furthermore,we extend the controllable topology of two-dimensional colloids by introducing singularities and disclinations in monodomain liquid crystals.Topological structures with defect strength from−2 to+2 were realized.This work provides a facile methodology to study the structural order of soft matter at a macroscopic level,facilitating the fabrication of metamaterials with tunable and highly anisotropic architectures.

Precise Thermoplastic Processing of Graphene Oxide Layered Solid by Polymer Intercalation

The processing capability is vital for the wide applications of materials to forge structures as-demand.Graphene-based macroscopic materials have shown excellent mechanical and functional properties.However,different from usual polymers and metals,graphene solids exhibit limited deformability and processibility for precise forming.Here,we present a precise thermoplastic forming of graphene materials by polymer intercalation from graphene oxide(GO)precursor.The intercalated polymer enables the thermoplasticity of GO solids by thermally activated motion of polymer chains.We detect a critical minimum containing of intercalated polymer that can expand the interlayer spacing exceeding 1.4 nm to activate thermoplasticity,which becomes the criteria for thermal plastic forming of GO solids.By thermoplastic forming,the flat GO-composite films are forged to Gaussian curved shapes and imprinted to have surface relief patterns with size precision down to 360 nm.The plastic-formed structures maintain the structural integration with outstanding electrical(3.07×10^(5) S m^(−1))and thermal conductivity(745.65 W m^(−1) K^(−1))after removal of polymers.The thermoplastic strategy greatly extends the forming capability of GO materials and other layered materials and promises versatile structural designs for more broad applications.

Advances and perspectives in environmental health research in China

Environmental health research aims to identify environmental conditions suitable for the healthy living and reproduction of human beings.Through the interdisciplinary research bridging environmental sciences and health/medical sciences,the impacts of physical,chemical,and biological environmental factors on human health are investigated.This includes identifying environmental factors detrimental to human health,evaluating human exposure characteristics to environmental factors,clarifying causal relationships between environmental exposure and health effects,analyzing the underlying biochemical mechanisms,linking environmental factors to the onset and progression of diseases,establishing exposure-response relationships,and determining effect thresholds.Ultimately,the results of environmental health research can serve as a scientific basis for formulating environmental management strategies and guiding prevention and intervention measures at both the public and individual levels.This paper summarizes the recent advances and future perspectives of environmental health research in China,as reported by a group of Chinese scientists who recently attended a workshop in Hainan,China.While it is not intended to provide a comprehensive review of this expansive field,it offers a glimpse into the significant progress made in understanding the health impacts of environmental factors over the past decade.Looking ahead,it is imperative not only to sustain efforts in studying the health effects of traditional environmental pollution,but also to prioritize research on the health impacts of emerging pollutants and climate change.

超稳定石墨烯气凝胶的电磁屏蔽性能研究

石墨烯气凝胶(GAs)在解决下一代电子器件电磁屏蔽污染方面引起了广泛关注.但是,由于超轻石墨烯气凝胶在复杂环境中结构不稳定,其在电磁屏蔽的实际应用中仍面临巨大的挑战.在此,我们提出一类机械结构稳定的石墨烯气凝胶,其展示出优异可靠的电磁屏蔽性能.这类气凝胶呈现出面面堆叠的结构,在密度ρ=3.7 mg cm-3,高度1 m m时,电磁屏蔽效能可达到64.1 d B,比电磁屏蔽效能达到173,243 dB cm2g-1,远超现有报道的碳基材料.同时,石墨烯气凝胶具有优异的环境适应性,在机械形变、极端温度、燃烧及水下等环境中均可保持性能稳定.此外,制备的石墨烯气凝胶可通过真空袋装工艺进行包装运输,解决了超轻材料实际应用中低密度与大体积的矛盾,且在这一极端变形过程中材料结构和性能均未产生破坏.该研究为石墨烯气凝胶电磁屏蔽材料的实际应用铺平了道路,且拓展了其实际应用场景,比如航天、军事战机及海洋领域.

Wrinkling modes of graphene oxide assembled on curved surfaces

Assembling two-dimensional(2D)sheets into macroscopic three-dimensional(3D)forms has created a promising material family with rich functionalities.Multiscale wrinkles are intrinsic features of 2D sheets in their 3D assembles.Therefore,the precise wrinkling modulation optimizes the transition of outstanding properties of 2D sheets to expected performances of assembled materials and dominates their fabrication process.The wrinkling evolution of 2D sheets assembling onto flat surfaces has been extensively understood,however,the wrinkling behaviors on the more generally curved surface still remain unclear.Here,we investigate the wrinkling behaviors of graphene oxide sheets assembled onto curved surfaces and reveal the selection rule of wrinkling modes that determined by the curvature mismatch between 2D sheets and target surfaces.We uncover that three wrinkling modes including isotropic cracked land,labyrinth,and anisotropic curtain phases,respectively emerge on flat,spherical,and cylindrical surfaces.A favorable description paradigm is offered to quantitatively measure the complex wrinkling patterns and assess the curvature mismatch constraint underlying the wrinkling mode selection.This research provides a general and quantitative description framework of wrinkling modulation of 2D materials such as high performance graphene fibers,and guides the precise fabrication of particles and functional coatings.

Phthalate levels in Chinese residences:Seasonal and regional variations and the implication on human exposure

Indoor pollution of manmade semivolatile organic compounds(SVOCs)such as phthalates are a growing threat to human health.Herein we summarize the dust-phase phthalate concentrations in Chinese residences reported from 2011 to 2021and simulate corresponding airborne concentrations based on equilibrium models.The simulation considers seasonal and regional variations in indoor temperature and PM_(2.5)concentration,in contrast to the common practice of using constant values.Results show that variations in these two environmental factors lead to up to ten-and six-fold variations in the monthly median gas-and particle-phase concentrations of phthalates,respectively,in residences in individual climate zones.For higher-vaporpressure species di-n-butyl phthalate and di-isobutyl phthalate,the resultant seasonal and regional variations in aggregate nondiet intake can reach six-and three-fold,respectively.These results have important implications on exposure assessment of SVOCs and epidemiological evaluation of their health effects.

Neuroinflammation in Parkinson’s disease and its potential as therapeutic target

Parkinson’s disease(PD),the second most common age-associated neurodegenerative disorder,is characterized by the loss of dopaminergic(DA)neurons and the presence ofα-synuclein-containing aggregates in the substantia nigra pars compacta(SNpc).Chronic neuroinflammation is one of the hallmarks of PD pathophysiology.Postmortem analyses of human PD patients and experimental animal studies indicate that activation of glial cells and increases in pro-inflammatory factor levels are common features of the PD brain.Chronic release of proinflammatory cytokines by activated astrocytes and microglia leads to the exacerbation of DA neuron degeneration in the SNpc.Besides,peripheral immune system is also implicated in the pathogenesis of PD.Infiltration and accumulation of immune cells from the periphery are detected in and around the affected brain regions of PD patients.Moreover,inflammatory processes have been suggested as promising interventional targets for PD and even other neurodegenerative diseases.A better understanding of the role of inflammation in PD will provide new insights into the pathological processes and help to establish effective therapeutic strategies.In this review,we will summarize recent progresses in the neuroimmune aspects of PD and highlight the potential therapeutic interventions targeting neuroinflammation.

Fabrication and mechanical properties of self-toughening ZrB2–SiC composites from in-situ reaction

Self-toughening ZrB2–SiC based composites are fabricated by in-situ reactive hot pressing.The effect of sintering additive content on the microstructure and mechanical properties of the composites is investigated.Microstructure observation found that the in-situ reactive hot pressing could promote the anisotropic growth of ZrB2 grains and the formation of interlocking microstructure.Such microstructure could improve the mechanical properties,especially,for the fracture toughness.The improved mechanical properties could be attributed to the self-toughening structure related to the ZrB2 platelets and the formed interlocking microstructure,which could trigger various toughening mechanisms such as grain pull-out,crack bridging,crack deflection,and crack branching,providing the main contribution to the high fracture toughness.

Tribenuron-Methyl Induces Male Sterility through Anther-Specific Inhibition of Acetolactate Synthase Leading to Autophagic Cell Death

Tribenuron-methyl （TM） is a powerful sulfonylurea herbicide that inhibits branched-chain amino acid （BCAA） biosynthesis by targeting the catalytic subunit （CSR1） of acetolactate synthase （ALS）. Selective in- duction of male sterility by foliar spraying of TM at low doses has been widely used for hybrid seed produc- tion in rapeseed （Brassica napus）; however, the underlying mechanism remains unknown. Here, we report greater TM accumulation and subsequent stronger ALS inhibition and BCAA starvation in anthers than in leaves and stems after TM application. Constitutive or anther-specific expression of csrl-lD （a CSR1 mutant） eliminated anther-selective ALS inhibition and reversed the TM-induced male sterile phenotype in both rapeseed and Arabidopsis. The results of TM daub-stem experiments, combined with the observations of little TM accumulation in anthers and reversion of TM-induced male sterility by targeted expression of the TM metabolism gene Bel in either the mesophyll or phloem, suggested that foliar-sprayed TM was polar-transported to anthers mainly through the mesophyll and phloem. Microscopy and immunoblotting revealed that autophagy, a bulk degradation process induced during cell death, was elevated in TM-induced male sterile anthers and by anther-specific knockdown of ALS. Moreover, TM-induced pollen abortion was significantly inhibited by the autophagy inhibitor 3-MA. These data suggested that TM was polar-transported to anthers, resulting in BCAA starvation via anther-specific ALS inhibition and, ulti- mately, autophagic cell death in anthers.

The enhanced permeability and retention effect based nanomedicine at the site of injury

The enhanced permeability retention(EPR)effect based nanomedicine has been widely used for tumor targeting during the past decades.Here we unexpectedly observed the similar"EPR effect"at the site of iniury.We found that the temporary dilated and leaky blood vessels caused by the potent vasodilator histamine in response to injury allowed the injected nanoparticles to pass through the vasculature and reached the injured tissue.Our finding shows the potential underline mechanism of"EPR effect"at the injured site.By loading with antibiotics,we further demonstrated a new strategy for prevention of infection at the site of injury.

Systematic characterization of transport and thermoelectric properties of a macroscopic graphene fiber

Graphene, a two-dimensional material with extraordinary electrical, thermal, and elastic performance, is a potential candidate for future technologies. However, the superior properties of graphene have not yet been realized for graphenederived macroscopic structures such as graphene fibers. In this study, we systematically investigated the temperature （T ）-dependent transport and thermoelectric properties of graphene fiber, including the thermal conductivity （A）, electrical conductivity （o）, and Seebeck coefficient （S）. A increases from 45.8 to 149.7 W·m^-1·K^-1 and then decreases as T increases from 80 to 290 K, indicating the boundary-scattering and three-phonon Umklapp scattering processes. σ increases with T from 7.1 × 10^4 to 1.18 × 10^5 S·m^-1, which can be best explained by the hopping mechanism. S ranges from -3.9 to 0.8 μV·K^-1 and undergoes a sign transition at approximately 100 K.

Dynamic dispersion stability of graphene oxide with metal ions

Graphene oxide(GO),an important chemical precursor of graphene,can stably disperse in aqueous surrounding and undergo aggregation as metal cations introduced.The usual instability of GO with ions is caused by the shielding effect of ions and crosslinking between GO and ions.However,the dynamic stability of GO under ions exchange still remains unclear.Here,we investigated the dynamic dispersion stability of GO with metal ions and observed a redispersion behavior in concentrated Fe3+solution,other than permanent aggregation.The exchange with Fe3+ions drives the reversion of zeta(ζ)potential and enables the redispersion to individual GO-Fe3+complex sheets,following a dynamic electric double layer(EDL)mechanism.It is found that the specifically strong electrostatic shielding effect and coordination attraction between Fe3+and functional oxygen groups allows the selective redispersion of GO in concentrated Fe3+solution.The revealed dynamic dispersion stability complements our understanding on the dispersive stability of GO and can be utilized to fabricate graphene-metal hybrids for rich applications.

Highly electrically conductive graphene papers via catalytic graphitization

The highly electrically conductive graphene papers prepared from graphene oxide have shown promising perspectives in flexible electronics,electromagnetic interference(EMI)shielding,and electrodes.To achieve high electrical conductivity,the graphene oxide precursor usually needs to be graphitized at extremely high temperature(~2,800°C),which severely increases the energy consumption and production costs.Here,we report an efficient catalytic graphitization approach to fabricate highly conductive graphene papers at lower annealing temperature.The graphene papers with boron catalyst annealed at 2,000°C show a high conductivity of~3,400 S·cm^(-1),about 47%higher than pure graphene papers.Boron catalyst facilitates the recovery of structural defects and improves the degree of graphitization by 80%.We further study the catalytic effect of boron on the graphitization behavior of graphene oxide.The results show that the activation energy of the catalytic graphitization process is as low as 80.1 kJ·mol^(–1)in the temperature ranges studied.This effective strategy of catalytic graphitization should also be helpful in the fabrication of other kinds of highly conductive graphene macroscopic materials.

Electrospinning of Neat Graphene Nanofbers

Macroscopic assembly of graphene sheets has renovated the preparation of neat carbonaceous fbers with integrating high performance and superior functionalities,beyond the pyrolysis of conventional polymeric precursors.To date,graphene microfbers by the liquid crystalline wet-spinning method have been established.However,how to reliably prepare continuous neat graphene nanofbers remains unknown.Here,we present the electrospinning of neat graphene nanofbers enabled by modulating colossally extensional fow state of graphene oxide liquid crystals.We use polymer with mega molecular weight as transient additives to realize the colossal extensional fow and electrospinning.The neat graphene nanofbers feature high electronic quality and crystallinity and exhibit high electrical conductivity of 2.02×10^(6) S/m that is to be comparable with single crystal graphite whisker.The electrospinning of graphene nanofbers was extended to prepare large-area fabric with high fexibility and superior specifc electrical/thermal conductivities.The electrospinning of graphene nanofbers opens the door to nanofbers of rich two-dimensional sheets and the neat graphene nanofbers may grow to be a new species after conventional carbonaceous nanofbers and whiskers in broad functional applications.

Kerogen——as a sort of organic bearer of gold in gold-bearing formations

Organic component, organic carbon and gold content analyses were used to study the relationship between gold mineralization and organic matter in major host rocks of three different chronological gold-bearing formations of South China. The results show that the organic matter of host rocks in various chronological major gold-bearing formations of South China has associated with gold mineralization in genesis. There is a positive correlation between gold and organic carbon in the host rocks of gold-bearing formations. Gold element was mainly enriched in insoluble organic matter——kerogen. Gold content of the kerogen is commonly higher from a few tens to several hundred times than that of the whole rocks, up to 5%—40% gold of the whole rocks. Gold remaining in the kerogen was considered an organic group of the kerogen to combine with ionic gold in solution through surface absorption, ion exchange complex reaction and chelation so that the kerogen could have become an important sort of organic bearer