We carried out new photometric observations of asteroid （106） Dione at three apparitions （2004, 2012 and 2015） to understand its basic physical properties. Based on a new brightness model, new photometric observat...We carried out new photometric observations of asteroid （106） Dione at three apparitions （2004, 2012 and 2015） to understand its basic physical properties. Based on a new brightness model, new photometric observational data and published data of （106） Dione were analyzed to characterize the morphology of Dione＇s photometric phase curve. In this brightness model, a cellinoid ellipsoid shape and three-parameter （H, G1, G2） magnitude phase function system were involved. Such a model can not only solve the phase function system parameters of （106） Dione by considering an asymmetric shape of an asteroid, but also can be applied to more asteroids, especially those without enough photometric data to solve the convex shape. Using a Markov Chain Monte Carlo （MCMC） method, Dione＇s absolute magnitude of H = 7.66＋0.03-0.03 mag, and phase function parameters G1 = 0.682＋0.077-0.077 and G2 = 0.081＋0.042-0.042 were obtained. Simultaneously, Dione＇s simplistic shape, orientation of pole and rotation period were also determined preliminarily.展开更多
The electrochemi luminescence <ecl> of a new reagent 6-<2-hydroxy-4-diethylaminophenylazo>-2, 3-dihydro-1, 4-phthatazine-1, 4-dione <HDEA> in basic aqueous solution was studied. Trace amount of silve...The electrochemi luminescence <ecl> of a new reagent 6-<2-hydroxy-4-diethylaminophenylazo>-2, 3-dihydro-1, 4-phthatazine-1, 4-dione <HDEA> in basic aqueous solution was studied. Trace amount of silver showed significant effect on the efficiency of light emission of HDEA during a positive trigonometrical wave pulse was exerted on the electrodes In the present paper, the ecl spectra of HDEA have been measured. λ_(max) is 410 nm. The reaction of HDEA chemiluminescence and the circular voltammetry, ultraviolet-visible spectrometry for the system have been investigated. The possible mechanism of the ecl of HDEA-KCL-KOH-Ag(I) system has been proposed.展开更多
2, 7-Diaminothieno[2, 3-d：5, 4-d]dipyrimidine-4, 5（3H, 6H）diones 4 were synthesized by a facile synthetic method, which includes bis-aza-Wittig reaction of bis-iminophosphorane 1 with aromatic isocyanate to give bi...2, 7-Diaminothieno[2, 3-d：5, 4-d]dipyrimidine-4, 5（3H, 6H）diones 4 were synthesized by a facile synthetic method, which includes bis-aza-Wittig reaction of bis-iminophosphorane 1 with aromatic isocyanate to give bis-carbodiimide 2 and subsequent reaction of 2 with various dialkylamine in the presence of solid K2CO3 or EtONa.展开更多
In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal ...In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.展开更多
Two-dimensional(2D) layered perovskites have emerged as potential alternates to traditional three-dimensional(3D)analogs to solve the stability issue of perovskite solar cells. In recent years, many efforts have been ...Two-dimensional(2D) layered perovskites have emerged as potential alternates to traditional three-dimensional(3D)analogs to solve the stability issue of perovskite solar cells. In recent years, many efforts have been spent on manipulating the interlayer organic spacing cation to improve the photovoltaic properties of Dion–Jacobson(DJ) perovskites. In this work, a serious of cycloalkane(CA) molecules were selected as the organic spacing cation in 2D DJ perovskites, which can widely manipulate the optoelectronic properties of the DJ perovskites. The underlying relationship between the CA interlayer molecules and the crystal structures, thermodynamic stabilities, and electronic properties of 58 DJ perovskites has been investigated by using automatic high-throughput workflow cooperated with density-functional(DFT) calculations.We found that these CA-based DJ perovskites are all thermodynamic stable. The sizes of the cycloalkane molecules can influence the degree of inorganic framework distortion and further tune the bandgaps with a wide range of 0.9–2.1 eV.These findings indicate the cycloalkane molecules are suitable as spacing cation in 2D DJ perovskites and provide a useful guidance in designing novel 2D DJ perovskites for optoelectronic applications.展开更多
Tin-lead(Sn-Pb)alloyed perovskites with tunable bandgaps hold great potential for constructing highly efficient single-junction and tandem photovoltaic devices.However,the efficiency and stability of Sn-Pb perovskite ...Tin-lead(Sn-Pb)alloyed perovskites with tunable bandgaps hold great potential for constructing highly efficient single-junction and tandem photovoltaic devices.However,the efficiency and stability of Sn-Pb perovskite solar cells(PSCs)are greatly hampered by severe nonradiative recombination due to the easy oxidation of Sn(II).In this work,we report the construction of mixed dimensional two-dimensional(2D)Dion–Jacobson(DJ)and three-dimensional(3D)perovskites to improve the efficiency and stability of Sn-Pb alloyed PSCs.Introducing a small amount of 1,4-butanediammonium diiodide as spacer cations of DJ perovskites into precursor,the prepared mixed dimensional Sn-Pb alloyed perovskites exhibit reduced trap-state density due to the passivation of 2D DJ perovskites.As a result,nonradiative charge recombination is greatly suppressed.The prepared Sn-Pb alloyed PSCs based on 2D-DJ/3D heterojunction deliver a power conversion efficiency of 19.02%with an impressive fill factor of 80%.As well,improved device stability is realized due to the presence of DJ perovskites which serves as a protection barrier against oxidation and water invasion.展开更多
Cyclodipeptide (3 S,6S ) bis(phenylmethyl)piperazine 2,5 dione was prepared in high yield by heating phenylalanine methyl ester in toluene under reflux. The reduction of this cyclodipeptide with sodium NaBH 4 B...Cyclodipeptide (3 S,6S ) bis(phenylmethyl)piperazine 2,5 dione was prepared in high yield by heating phenylalanine methyl ester in toluene under reflux. The reduction of this cyclodipeptide with sodium NaBH 4 BF 3 in DME gave the (2 S,5S ) bis(phenylmethyl)piperazine, which, on heating with ethylene bromide and triethylamine, afforded the title compounds. This method was proved to be generally applicable to the synthesis of C 2 symmetric 2,5 disubstituted 1,4 diazabicyclo[2.2.2]octane from the corresponding natural or unnatural amino acid esters.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.11073051,11473066 and 11673063)the Open Project of Key Laboratory of Space Object and Debris Observation,Chinese Academy of Sciences(title:Photometric study of space debris in near geostationary orbit)
文摘We carried out new photometric observations of asteroid （106） Dione at three apparitions （2004, 2012 and 2015） to understand its basic physical properties. Based on a new brightness model, new photometric observational data and published data of （106） Dione were analyzed to characterize the morphology of Dione＇s photometric phase curve. In this brightness model, a cellinoid ellipsoid shape and three-parameter （H, G1, G2） magnitude phase function system were involved. Such a model can not only solve the phase function system parameters of （106） Dione by considering an asymmetric shape of an asteroid, but also can be applied to more asteroids, especially those without enough photometric data to solve the convex shape. Using a Markov Chain Monte Carlo （MCMC） method, Dione＇s absolute magnitude of H = 7.66＋0.03-0.03 mag, and phase function parameters G1 = 0.682＋0.077-0.077 and G2 = 0.081＋0.042-0.042 were obtained. Simultaneously, Dione＇s simplistic shape, orientation of pole and rotation period were also determined preliminarily.
基金This work was supported by National Natural Science Foundation of China
文摘The electrochemi luminescence <ecl> of a new reagent 6-<2-hydroxy-4-diethylaminophenylazo>-2, 3-dihydro-1, 4-phthatazine-1, 4-dione <HDEA> in basic aqueous solution was studied. Trace amount of silver showed significant effect on the efficiency of light emission of HDEA during a positive trigonometrical wave pulse was exerted on the electrodes In the present paper, the ecl spectra of HDEA have been measured. λ_(max) is 410 nm. The reaction of HDEA chemiluminescence and the circular voltammetry, ultraviolet-visible spectrometry for the system have been investigated. The possible mechanism of the ecl of HDEA-KCL-KOH-Ag(I) system has been proposed.
基金We gratefully acknowledge financial support of this work by the National Key Project for Basic Research(2003CB114400,2003CB114406)the National Natural Science Foundation of China(Project No.20372023 and 20102001).
文摘2, 7-Diaminothieno[2, 3-d：5, 4-d]dipyrimidine-4, 5（3H, 6H）diones 4 were synthesized by a facile synthetic method, which includes bis-aza-Wittig reaction of bis-iminophosphorane 1 with aromatic isocyanate to give bis-carbodiimide 2 and subsequent reaction of 2 with various dialkylamine in the presence of solid K2CO3 or EtONa.
基金supported by 2013 Research Grant(C100983401-01) from Kangwon National University
文摘In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.
基金supported by the National Natural Science Foundation of China (Grant No. 62004080)the Postdoctoral Innovative Talents Supporting Program (Grant No. BX20190143)the China Postdoctoral Science Foundation (Grant No. 2020M670834)。
文摘Two-dimensional(2D) layered perovskites have emerged as potential alternates to traditional three-dimensional(3D)analogs to solve the stability issue of perovskite solar cells. In recent years, many efforts have been spent on manipulating the interlayer organic spacing cation to improve the photovoltaic properties of Dion–Jacobson(DJ) perovskites. In this work, a serious of cycloalkane(CA) molecules were selected as the organic spacing cation in 2D DJ perovskites, which can widely manipulate the optoelectronic properties of the DJ perovskites. The underlying relationship between the CA interlayer molecules and the crystal structures, thermodynamic stabilities, and electronic properties of 58 DJ perovskites has been investigated by using automatic high-throughput workflow cooperated with density-functional(DFT) calculations.We found that these CA-based DJ perovskites are all thermodynamic stable. The sizes of the cycloalkane molecules can influence the degree of inorganic framework distortion and further tune the bandgaps with a wide range of 0.9–2.1 eV.These findings indicate the cycloalkane molecules are suitable as spacing cation in 2D DJ perovskites and provide a useful guidance in designing novel 2D DJ perovskites for optoelectronic applications.
基金supported by the National Natural Science Foundation of China(No.62174069)Natural Science Foundation of Guangdong Province(No.2020A1515010853).
文摘Tin-lead(Sn-Pb)alloyed perovskites with tunable bandgaps hold great potential for constructing highly efficient single-junction and tandem photovoltaic devices.However,the efficiency and stability of Sn-Pb perovskite solar cells(PSCs)are greatly hampered by severe nonradiative recombination due to the easy oxidation of Sn(II).In this work,we report the construction of mixed dimensional two-dimensional(2D)Dion–Jacobson(DJ)and three-dimensional(3D)perovskites to improve the efficiency and stability of Sn-Pb alloyed PSCs.Introducing a small amount of 1,4-butanediammonium diiodide as spacer cations of DJ perovskites into precursor,the prepared mixed dimensional Sn-Pb alloyed perovskites exhibit reduced trap-state density due to the passivation of 2D DJ perovskites.As a result,nonradiative charge recombination is greatly suppressed.The prepared Sn-Pb alloyed PSCs based on 2D-DJ/3D heterojunction deliver a power conversion efficiency of 19.02%with an impressive fill factor of 80%.As well,improved device stability is realized due to the presence of DJ perovskites which serves as a protection barrier against oxidation and water invasion.
基金theNaturalScienceFoundationofJiangsuEducationOffice (No .0 1KJB15 0 0 0 2 )
文摘Cyclodipeptide (3 S,6S ) bis(phenylmethyl)piperazine 2,5 dione was prepared in high yield by heating phenylalanine methyl ester in toluene under reflux. The reduction of this cyclodipeptide with sodium NaBH 4 BF 3 in DME gave the (2 S,5S ) bis(phenylmethyl)piperazine, which, on heating with ethylene bromide and triethylamine, afforded the title compounds. This method was proved to be generally applicable to the synthesis of C 2 symmetric 2,5 disubstituted 1,4 diazabicyclo[2.2.2]octane from the corresponding natural or unnatural amino acid esters.
