Estimation of gases emitted by forest fires based on remote sensing data

Forest fire, an important agent for change in many forest ecosystems, plays an important role in atmo- spheric chemical cycles and the carbon cycle. The primary emissions from forest fire, CO2, CO, CH4, long-chained hydrocarbons and volatile organic oxides, however, have not been well quantified. Quantifying the carbonaceous gas emissions of forest fires is a critical part to better under- stand the significance of forest fire in calculating carbon balance and forecasting climate change. This study uses images from Enhanced Thematic Mapper Plus （ETM＋） on the Earth-observing satellite LANDSAT-7 for the year 2005 to estimate the total gases emitted by the 2006 Kanduhe forest fire in the Daxing＇an Mountains. Our results suggest that the fire emitted approximately 149,187.66 t CO2, 21,187.70 t CO, 1925.41 t CxHy, 470.76 t NO and 658.77 t SO2. In addition, the gases emitted from larch forests were significantly higher than from both broadleaf-needle leaf mixed forests and broadleaf mixed forests.

Research progress on construction and energy storage performance of MXene heterostructures

MXenes are a family of two-dimensional (2D) transition metal carbides, carbonitrides/nitrides with superior physical and chemical properties, which have attracted extensive attention since the discovery in 2011. The impressive electrochemical activity of MXene makes it one of the most potential electrode materials in rechargeable batteries and supercapacitors. However, single-component MXene electrodes are difficult to achieve high specific capacity, efficient ion/electron transport, and high stability compatibility in an electrochemical environment. Studies have shown that it is an effective method to introduce nanomaterials between MXene layers to construct heterostructures and to improve the electrochemical performance through the synergistic effect among the components in the heterostructures. The introduction of nanomaterials can effectively suppress the restacking of MXene nanosheets, shorten the diffusion path of ions and promote the electrolyte transport, which is beneficial to enhance the rate performance of MXene;moreover, the excellent mechanical flexibility of MXene can reduce the volume expansion of nanomaterials during charge/discharge, thereby effectively protecting the integrity of the electrode structure and improving the cycling stability. Therefore, in this review, combined with theoretical calculations, we summarize the recent advances of MXene heterostructures in terms of synthesis strategies and energy storage applications, including supercapacitors, metal-ions batteries (Li, Na, K, Mg, Zn, Al) and metal anode protection. Furthermore, potential challenges and application perspectives for MXene heterostructures are also outlined.

Anatomical Evidence for the Neural Connection from the Emotional Brain to Autonomic Innervation in the Anterior Chamber Structures of the Eye

Objective Previous studies have shown that the autonomic nervous system(ANS),which can be affected by emotions,is important in the occurrence or progression of glaucoma.The autonomic innervation distributed in the anterior chamber(AC)structures might play an efferent role in the neural regulation of intraocular pressure(IOP).This study aimed to investigate the anatomic neural connection from the emotional brain to autonomic innervation in the AC.Methods A retrograde trans-multisynaptic pseudorabies virus encoded with an enhanced green fluorescent protein(PRV531)and non-trans-synaptic tracer FAST Dil were injected into the right eye of mice,respectively.Fluorescent localization in the emotional brain and preganglionic nuclei was studied.Five and a half days after PRV531 injection into the right AC,fluorescent signals were observed in several emotional brain regions,including the amygdala,agranular insular cortex,lateral septal nuclei,periaqueductal gray,and hypothalamus.Autonomic preganglionic nuclei,including Edinger-Westphal nucleus,superior salivatory nucleus,and intermediolateral nucleus,were labeled using PRV531.Results The sensory trigeminal nuclei were not labeled using PRV531.The fluorescence signals in the nuclei mentioned above showed bilateral distribution,primarily on the ipsilateral side.Seven days after injecting FAST Dil into the AC,we observed no FAST Dil-labeled neurons in the central nervous system.Conclusion Our results indicate a neural connection from the emotional brain to autonomic innervation in the AC,which provides anatomical support for the emotional influence of IOP via the ANS.

A Non-canonical Excitatory PV RGC–PV SC Visual Pathway for Mediating the Looming-evoked Innate Defensive Response

Parvalbumin-positive retinal ganglion cells(PV+RGCs)are an essential subset of RGCs found in various species.However,their role in transmitting visual information remains unclear.Here,we characterized PV+RGCs in the retina and explored the functions of the PV+RGC-mediated visual pathway.By applying multiple viral tracing strategies,we investigated the downstream of PV+RGCs across the whole brain.Interestingly,we found that the PV+RGCs provided direct monosynaptic input to PV+excitatory neurons in the superficial layers of the superior colliculus(SC).Ablation or suppression of SC-projecting PV+RGCs abolished or severely impaired the flight response to looming visual stimuli in mice without affecting visual acuity.Furthermore,using transcriptome expression profiling of individual cells and immunofluorescence colocalization for RGCs,we found that PV+RGCs are predominant glutamatergic neurons.Thus,our findings indicate the critical role of PV+RGCs in an innate defensive response and suggest a non-canonical subcortical visual pathway from excitatory PV+RGCs to PV+SC neurons that regulates looming visual stimuli.These results provide a potential target for intervening and treating diseases related to this circuit,such as schizophrenia and autism.

Interface boosted highly efficient selective photooxidation in Bi_(3)O_(4)Br/ Bi_(2)O_(3) heterojunctions

Selective photooxidation of amines to biologically important imines is in great demand for industrial applications.The conversion efficiency and selectivity of the process are strongly dependent on the activation of photocatalytic molecular oxygen(O_(2))into reactive oxygen species.Here,we propose the construction of rich interfaces to boost photocatalytic O_(2) activation by facilitating the transfer of photocarriers.Taking Bi_(3)O_(4)Br/Bi_(2)O_(3) heterojunctions as an example,rich interfaces facilitate electron transfer to adsorbed O_(2) for superoxide(O_(2)⋅^(-))generation,thus achieving≥98%conversion efficiency and selectivity for benzylamine and benzylamine derivatives.This study offers a valid method to design advanced photocatalysts for selective oxidation reactions.

Synthesis of Mo_(2)C MXene with high electrochemical performance by alkali hydrothermal etching

Two-dimensional MXenes are generally prepared by the etching of acid solutions.The as-synthesized MXenes are terminated by acid group anions(F^(–),Cl^(–),etc.),which affect the electrochemical performance of MXenes.Here,we report a novel method to prepare Mo_(2)C MXene from Mo_(2)Ga_(2)C by the hydrothermal etching of alkali solutions.Highly pure Mo_(2)C MXene was successfully synthesized by the etching of NaOH,while the etchings of LiOH and KOH were failed.The concentration of NaOH,temperature,and time strongly affect the purity of as-prepared MXene.Pure Mo_(2)C MXene could be synthesized by the etching of 20 M NaOH at 180 for 24 h.After℃intercalation by hexadecyl trimethyl ammonium bromide at 90 for 96 h,few℃-layer Mo_(2)C MXene was obtained.The Mo_(2)C MXene made by NaOH etching after intercalation exhibited excellent performance as anode of lithium-ion battery,compared with general Mo_(2)C MXene made by HF etching and the Mo_(2)C MXene reported in literature.The final discharge specific capacity was 266.73 mAh·g^(−1)at 0.8 A·g^(−1),which is 52%higher than that Mo_(2)C made by HF etching(175.77 mAh·g^(−1)).This is because Mo_(2)C MXene made by NaOH etching has lager specific surface area,lower resistance,and pure O/OH termination without acid anion termination.This is the first report to make Mo_(2)C MXene by alkali etching and the samples made by this method exhibited significantly better electrochemical performance than the samples made by general HF etching.

Engineering Exciton-Phonon Interactions for Suppressing Nonradiative Energy Loss in Energy-Transfer-Initiated Photocatalysis

The prevalent excitonic effects in low-dimensional semiconductors enable energy-transfer-initiated photocatalytic solar-to-chemical energy conversion.However,the generally strong interactions between excitons and lattice vibrations in these low-dimensional systems lead to robust nonradiative energy loss,which inevitably impedes photocatalytic performance of energy-transfer-initiated reactions.Herein,we highlight the crucial role of engineering exciton-phonon interactions in suppressing nonradiative energy losses in low-dimensional semiconductor-based photocatalysts.By taking bismuth oxybromide(BiOBr)as an example,we demonstrate that phonon engineering could be effectively implemented by introducing Bi-Br vacancy clusters.Based on nonadiabatic molecular dynamics simulations and spectroscopic investigations,we demonstrate that the defective structure can promote exciton-low-frequency phonon coupling and reduce exciton-high-frequency optical phonon coupling.Benefiting from the tailored couplings,nonradiative decay of excitons in defective BiOBr is significantly suppressed,thereby facilitating exciton accumulation and hence energy-transfer-initiated photocatalysis.

Density-functional-theory predictions of mechanical behaviour and thermal properties as well as experimental hardness of the Ga-bilayer Mo_(2)Ga_(2)C

Mo_(2)Ga_(2)C is a new MAX phase with a stacking Ga-bilayer as well as possible unusual properties.To understand this unique MAX phase structure and promote possible future applications,the structure,chemical bonding,and mechanical and thermodynamic properties of Mo_(2)Ga_(2)C were investigated by first-principles.Using the“bond stiffness”model,the strongest covalent bonding(1162 GPa)was formed between Mo and C atoms in Mo_(2)Ga_(2)C,while the weakest Ga–Ga(389 GPa)bonding was formed between two Ga-atomic layers,different from other typical MAX phases.The ratio of the bond stiffness of the weakest bond to the strongest bond(0.33)was lower than 1/2,indicating the high damage tolerance and fracture toughness of Mo_(2)Ga_(2)C,which was confirmed by indentation without any cracks.The high-temperature heat capacity and thermal expansion of Mo_(2)Ga_(2)C were calculated in the framework of quasi-harmonic approximation from 0 to 1300 K.Because of the metal-like electronic structure,the electronic excitation contribution became more significant with increasing temperature above 300 K.

Divergent Projection Patterns Revealed by Reconstruction of Individual Neurons in Orbitofrontal Cortex

The orbitofrontal cortex(OFC)is involved in diverse brain functions via its extensive projections to multiple target regions.There is a growing understanding of the overall outputs of the OFC at the population level,but reports of the projection patterns of individual OFC neurons across different cortical layers remain rare.Here,by combining neuronal sparse and bright labeling with a whole-brain florescence imaging system(fMOST),we obtained an uninterrupted three-dimensional whole-brain dataset and achieved the full morphological reconstruction of 25 OFC pyramidal neurons.We compared the wholebrain projection targets of these individual OFC neurons in different cortical layers as well as in the same cortical layer.We found cortical layer-dependent projections characterized by divergent patterns for information delivery.Our study not only provides a structural basis for understanding the principles of laminar organizations in the OFC,but also provides clues for future functional and behavioral studies on OFC pyramidal neurons.

Rapid and Sparse Labeling of Neurons Based on the Mutant Virus-Like Particle of Semliki Forest Virus

Sparse labeling of neurons contributes to uncovering their morphology, and rapid expression of a fluorescent protein reduces the experiment range. To achieve the goal of rapid and sparse labeling of neurons in vivo, we established a rapid method for depicting the fine structure of neurons at 24 h post-infection based on a mutant viruslike particle of Semliki Forest virus. Approximately 0.014 fluorescent focus-forming units of the mutant virus-like particle transferred enhanced green fluorescent protein into neurons in vivo, and its affinity for neurons in vivo was stronger than for neurons in vitro and BHK21(baby hamster kidney) cells. Collectively, the mutant virus-likeparticle provides a robust and convenient way to reveal the fine structure of neurons and is expected to be a helper virus for combining with other tools to determine their connectivity. Our work adds a new tool to the approaches for rapid and sparse labeling of neurons in vivo.

Construction and performance of CdS/MoO_(2)@Mo_(2)C-MXene photocatalyst for H_(2) production

Nowadays,photocatalytic technologies are regarded as promising strategies to solve energy problems,and various photocatalysts have been synthesized and explored.In this paper,a novel CdS/MoO_(2)@Mo_(2)C-MXene photocatalyst for H_(2)production was constructed by a two-step hydrothermal method,where MoO_(2)@Mo_(2)C-MXene acted as a binary co-catalyst.In the first hydrothermal step,MoO_(2)crystals with an egged shape grew on the surface of two-dimensional(2D)Mo_(2)C MXene via an oxidation process in HCl aqueous solution.In the second hydrothermal step,CdS nanorods were uniformly assembled on the surface of MoO_(2)@Mo_(2)C-MXene in ethylenediamine with an inorganic cadmium source and organic sulfur source.The CdS/MoO_(2)@Mo_(2)C-MXene composite with MoO_(2)@Mo_(2)C-MXene of 5 wt%exhibits an ultrahigh visible-light photocatalytic H_(2)production activity of 22,672μmol/(g·h),which is~21%higher than that of CdS/Mo_(2)C-MXene.In the CdS/MoO_(2)@Mo_(2)C-MXene composite,the MoO_(2)with metallic nature separates CdS and Mo_(2)C MXene,which acts as an electron-transport bridge between CdS and Mo_(2)C MXene to accelerate the photoinduced electron transferring.Moreover,the energy band structure of CdS was changed by MoO_(2)@Mo_(2)C-MXene to suppress the recombination of photogenerated carriers.This novel compound delivers upgraded photocatalytic H_(2)evolution performance and a new pathway of preparing the low-cost photocatalyst to solve energy problems in the future.

Surface modification boosts exciton extraction in confined layered structure for selective oxidation reaction

Extracting photogenerated species from bulk to surface is an essential process for gaining efficient semiconductor-based photocatalysis.However,compared with charged photogenerated carriers,neutral exciton exhibits negligible response to electric field.Accordingly,traditional strategies involving band-alignment construction for boosting directional transfer of charge carriers are impracticable for extracting bulk excitons.To this issue,we here propose that the extraction of bulk exciton could be effectively implemented by surface modification.By taking confined layered bismuth oxycarbonate(Bi_(2)O_(2)CO_(3))as an example,we highlight that the incorporation of iodine atoms on the surface could modify the micro-region electronic structure and hence lead to reduced energy of surface excitonic states.Benefiting from the energy gradient between bulk and surface excitonic states,iodine-modified Bi_(2)O_(2)CO_(3)possesses high-efficiency bulk exciton extraction,and hence exhibits promoted performance in triggering1 O2-mediated selective oxidation reaction.This work presents the positive role of surface modification in regulating excitonic processes of semiconductor-based photocatalysts.