Medium J^(1/2)-clean环和Medium J^(1/2)-∗-clean环

作为Medium*-clean环的推广,本文引入了Medium J^(1/2)-clean环和Medium J^(1/2)-∗-clean环的概念,研究了这两类环的基本性质和扩张性质,并考虑它们与一些特殊环之间的联系。

An Improved Pair Method to Probe the Dust Extinction Law

Dust extinction law is crucial to recover the intrinsic energy distribution of celestial objects and infer the characteristics of interstellar dust.Based on the traditional pair method,an improved pair method is proposed to model the dust extinguished spectral energy distribution(SED)of an individual star.Instead of the mathematically parameterizing extinction curves,the extinction curves in this work are directly from the silicate-graphite dust model,so that the dust extinction law can be obtained and the dust properties can be analyzed simultaneously.The ATLAS9 stellar model atmosphere is adopted for the intrinsic SEDs in this work,while the silicate-graphite dust model with a dust size distribution of dn da~a^(-a)exp(-a a_(c)),0.005<a<5μmfor each component is adopted for the model extinction curves.One typical extinction tracer in the dense region(V410 Anon9)and one in the diffuse region(Cyg OB2#12)of the Milky Way are chosen to test the reliability and the practicability of the improved pair method in different stellar environments.The results are consistent with their interstellar environments and are in agreement with the previous observations and studies,which prove that the improved pair method is effective and applicable in different stellar environments.In addition to the reliable extinction results,the derived parameters in the dust model can be used to analyze the dust properties,which cannot be achieved by other methods with the mathematical extinction models.With the improved pair method,the stellar parameters can also be inferred and the extinction law beyond the wavelengths of observed data can be predicted based on the dust model as well.

Maximizing seed germination in two Acacia species

Revegetation of disturbed land, particularly in arid environment, is often hindered by low seedling establishment. Information on seed biology and germination cues of valuable species is lacking. We investigated seed germination of two Acacia species （Acacia tortilis （Forsk.） Hayne and Acacia oerfota （Forssk） schwein/）, required for nitrogen fixation and rehabilitation of arid and semi-arid areas.（four pregermination seed treatments were applied in order to find the best treatment in germinating acacia species. The medium was L2 and three replicates were used. Seeds pretreated with sand paper and also with H2SO4 and then H2O2 had the highest germination percentage in both species. The lowest germination percentage resulted from soaking seeds in water for 48 h followed by soaking in H2SO4 for A. oerfota and from soaking in water for 24 h for A. tortilis. Because the use of sand paper is difficult and time consuming, we recommend pretreatment ofA. tortilis and A. oerfota seeds with H2SO4 and H2O2 before planting. Our study results are significant for conservation agencies with an interest in optimizing germination in arid zones for rehabilitation and reforestation.

The adjustment of γ-aminobutyric acid_A tonic subunits in Huntington＇s disease：from transcription to translation to synaptic levels into the neostriatum

γ-Aminobutyric acid（GABA）,plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is responsible to render tonic inhibition by pentameric receptors containing α4-6,β3,δ,or ρ1-3 subunits,they are located at perisynaptic and/or in extrasynaptic regions.The biophysical properties of GABAA tonic inhibition have been related with cellular protection against excitotoxic injury and cell death in presence of excessive excitation.On this basis,GABAA tonic inhibition has been proposed as a potential target for therapeutic intervention of Huntington＇s disease.Huntington＇s disease is a neurodegenerative disorder caused by a genetic mutation of the huntingtin protein.For experimental studies of Huntington＇s disease mouse models have been developed,such as R6/1,R6/2,Hdh Q92,Hdh Q150,as well as YAC128.In all of them,some key experimental reports are focused on neostriatum.The neostriatum is considered as the most important connection between cerebral cortex and basal ganglia structures,its cytology display two pathways called direct and indirect constituted by medium sized spiny neurons expressing dopamine D1 and D2 receptors respectively,they display strong expression of many types of GABAA receptors,including tonic subunits.The studies about of GABAA tonic subunits and Huntington＇s disease into the neostriatum are rising in recent years,suggesting interesting changes in their expression and localization which can be used as a strategy to delay the cellular damage caused by the imbalance between excitation and inhibition,a hallmark of Huntington＇s disease.

Generation of multi-wavelength erbium-doped fiber laser by using MoSe2 thin film as nonlinear medium and stabilizer

We experimentally demonstrate the application of MoSe2 thin film as a nonlinear medium and stabilizer to generate a multi-wavelength erbium-doped fiber laser. The cooperation of a photonic crystal fiber and a polari- zation-dependent isolator induces unstable multi-wavelength oscillations based on the nonlinear polarization rotation effect. A MoSe2 thin film is further incorporated into the cavity to achieve a stable multi-wavelength. The laser generates 7 lasings with a constant spacing of 0.47 nm at a pump power of 250 roW. The nmlti- wavelength erbium-doped fiber laser is stable with power fluctuations of less than 5 dB over 30 min.

Dual role of lipids for genome stability and pluripotency facilitates full potency of mouse embryonic stem cells

While Mek1/2 and Gsk3βinhibition("2i")supports the maintenance of murine embryonic stem cells(EsCs)in a homogenous naive state,prolonged culture in 2i results in aneuploidy and DNA hypomethylation that impairs developmental potential.Additionally,2i fails to support derivation and culture of fully potent female ESCs.Here we find that mouse ESCs cultured in 2i/LIF supplemented with lipid-rich albumin(AlbuMAx)undergo pluripotency transition yet maintain genomic stability and full potency over long-term culture.Mechanisticaily,lipids in AlbuMAx impact intracellular metabolism including nucleotide biosynthesis,lipid biogenesis,and TCA cycle intermediates,with enhanced expression of DNMT3s that prevent DNA hypomethylation.Lipids induce a formative-like pluripotent state through direct stimulation of Erk2 phosphorylation,which also alleviates X chromosome loss in female ESCs.Importantly,both male and female"all-ESc"mice can be generated from de novo derived ESCs using AlbuMAXbased media.Our findings underscore the importance of lipids to pluripotency and link nutrient cues to genome integrity in early development.