The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,16Ne.This study investigates the structure and the in...The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,16Ne.This study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel method.The results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave component.However,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C pair.Additionally,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of decay.The observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.展开更多
Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an ef...Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.展开更多
3,3′-Dimethyl-dibenzo-18-crown-6 was synthesized and characterized by elemental analysis, FT-IR, ^1H NMR, UV, MS spectra and X-ray single-crystal diffraction. It belongs to orthorhombic, space group Pna21 with a = 8....3,3′-Dimethyl-dibenzo-18-crown-6 was synthesized and characterized by elemental analysis, FT-IR, ^1H NMR, UV, MS spectra and X-ray single-crystal diffraction. It belongs to orthorhombic, space group Pna21 with a = 8.0790（18）, b = 16.780（4）, c = 15.222（3） .A, Z= 4, V= 2063.6（8） A3 Dc = 1.250 g/cm^3,μ = 0.090 mm^-1, F（000） = 832, R = 0.0474 and wR = 0.1103. According to structural analysis, the title compound possesses a boat-like configuration.展开更多
The normal development and optimal functioning of the brain requires a vigilant immune surveillance system to detect and remove potential risk factors and prevent infection and tissue damage. Microglia are the residen...The normal development and optimal functioning of the brain requires a vigilant immune surveillance system to detect and remove potential risk factors and prevent infection and tissue damage. Microglia are the resident immune cells and the frontline defenders responsible for the immune response of the brain. Resting microglia possess a ramified morphology with numerous thin processes that continuously sample the environment. In response to inflammatory signals, microglia become activated and transform their morphology into a thick, amoeboid-like shape. Activated microglia proliferate, tolerate to sites of iniurv,展开更多
The trinuclear complex bis（18-crown-6）thallium tetracyanoplatinate [Tl2（1 8-crown- 6）2Pt（CN）4]·2H2O was prepared and its structure was determined by X-ray diffraction analysis. The compound （C28H52N4O14PtT...The trinuclear complex bis（18-crown-6）thallium tetracyanoplatinate [Tl2（1 8-crown- 6）2Pt（CN）4]·2H2O was prepared and its structure was determined by X-ray diffraction analysis. The compound （C28H52N4O14PtTl2, Mr = 1272.57） crystallizes in monoclinic, space group P21/n with a = 10.5180（10）, b = 8.6162（8）, c = 21.118（2） A, β= 92.577（2）°, V= 1911.9（3） A^3, Z = 2, Dc = 2.211 g/cm^3, F（000） = 1200,μ= 12.123 mm^-1, R = 0.0181 and wR = 0.0427. The linearly arranged three metals are sandwiched by two 18-crown-6 molecules.展开更多
The reactions of 18 crown 6 with each of K 2(M=Zn, Hg; mnt=1,2 dicyanoethene 1,2 dithiolate, C 2S 2(CN) 2- 2) were studied and novel complexes [K(18 C 6)] 2[Zn(mnt) 2](1) and [K(18 C 6)] 2[Hg(mnt)...The reactions of 18 crown 6 with each of K 2(M=Zn, Hg; mnt=1,2 dicyanoethene 1,2 dithiolate, C 2S 2(CN) 2- 2) were studied and novel complexes [K(18 C 6)] 2[Zn(mnt) 2](1) and [K(18 C 6)] 2[Hg(mnt) 2](2) were characterized by elemental analysis, IR spectrum and X ray diffraction analysis. Complex 1 displays a one dimensional chain of [K(18 C 6)] 2[Zn(mnt) 2] bridged by K O interactions between adjacent [K(18 C 6)] + units. Complex 2 is also a one dimensional chain of [K(18 C 6)] 2[Hg(mnt) 2] bridged by K...S weak interactions between adjacent [K(18 C 6)] + and [Hg(mnt) 2] 2- .展开更多
Diaza Crown ethers are versatile complexing reagents, their complexing abilities are dramatically modified by the electron donating atoms on substituents attached to the nitrogen if they can give a three-dimensional c...Diaza Crown ethers are versatile complexing reagents, their complexing abilities are dramatically modified by the electron donating atoms on substituents attached to the nitrogen if they can give a three-dimensional cavity as in cryptates. Hence the synthesis and characterization of bibracchial lariat ethers (BIBLES) have received much attention. In the preparation of new BIBLES, a complex Ⅱ was unexpectedly obtained.展开更多
A novel derivative of glycyrrhetinic acid, （E）-ethyl 3-keto-18β-glycyrrhetinate 3- oxime C32H49NO4 （Mr = 511.72）, was synthesized and structurally characterized by IR, 1^H NMR and single-crystal X-ray diffraction...A novel derivative of glycyrrhetinic acid, （E）-ethyl 3-keto-18β-glycyrrhetinate 3- oxime C32H49NO4 （Mr = 511.72）, was synthesized and structurally characterized by IR, 1^H NMR and single-crystal X-ray diffraction. It belongs to monoclinic, space group P21, with a = 12.4897（12）, b = 7.3190（7）, c = 15.9944（14）A, β = 94.833（2）o, V = 1456.9（2）A^3, Z = 2, Dc = 1.167 g/cm^3, μ = 0.075 mm^-1, F（000） = 560, the final R = 0.0449 and wR = 0.1122. A total of 7486 reflections were collected, of which 2785 were independent （Rint = 0.0199） and 2605 were observed with I 〉 2σ（I）. There exists an intermolecular hydrogen bond which helps to stabilize the crystal structure.展开更多
The structure of Na_2H_2[H_2V_2W_(18)O_(62)]12H_2O has been determined by x-ray analysis.The crystals are trigonal,space group R3m,with cell parameters a=37.613(11),c=12.972(7)A,V=15901(13)A^3,and Z=9.The structure mo...The structure of Na_2H_2[H_2V_2W_(18)O_(62)]12H_2O has been determined by x-ray analysis.The crystals are trigonal,space group R3m,with cell parameters a=37.613(11),c=12.972(7)A,V=15901(13)A^3,and Z=9.The structure model was refined by full-matrix least square to R=0.065 for 1702 reflections with F>4σ(F). The existence of the[H_2V_2W_(18)O_(62)]^(4-)heteropolyanion in the crystals has been confirmed.It is composed of two VO_4 tetrahedra and eighteen WO_6 octahedra linked to gve the Dawson-type structure.展开更多
The title complex [K (dndb ) (H2O) (NCS ) ], (dndb = trans-dinitro-dibenzo-- 18 -- crown -- 6 -- ether ) crystallied in triclinic system, space group Pl wit h unit celldimensions a= 7. 844 (4), b= 11. 979(8), c= 14. 4...The title complex [K (dndb ) (H2O) (NCS ) ], (dndb = trans-dinitro-dibenzo-- 18 -- crown -- 6 -- ether ) crystallied in triclinic system, space group Pl wit h unit celldimensions a= 7. 844 (4), b= 11. 979(8), c= 14. 436(11) A; a= 75. 62(6), β=80. 15(5), γ= 71. 94(5)°, M.= 1131. 39, V= 1243(2) A3, Z= l, F(000) = 588, D.= 1. 511 g/cm3, μ= 10. 5 cm-l (MoKa). The final R= 0. 045 for 2740 observed reflections (I＞3σ). The title complex molecule is a dimer complex and the potassium(I) ionis nine--coordinated, being bonded to one NCS-- anion, one H2O molecule, six oxygenatoms of a crown ether ligand and an oxygen atom of a nitro of another crown ether ligand. The potassium(I) ion and the nine atoms bonded with it are all in two planeswhich are approximately vertical with each other. The trans--dinitro-- dibenzo-- 18 -- crown6 is a heptadentate ligand.展开更多
Picoeukaryotes(<2-3μm)are major oceanic primary producers and play a crucial role for the functioning of marine ecosystems.However,the community structure of such communities remains poorly understood,especially i...Picoeukaryotes(<2-3μm)are major oceanic primary producers and play a crucial role for the functioning of marine ecosystems.However,the community structure of such communities remains poorly understood,especially in the East China Sea(ECS).We investigated the seasonal variations of abundance and diversity of picoeukaryotes,and recorded environmental variables,along a transect in Zhoushan Fishing Ground.High-throughput sequencing was used for sequencing the V4-V5 variable region within the 18S rRNA gene to analyze genetic diversity and relative abundance of picoeukaryotes.A total of 40 phyla,68 classes,99 orders,126 families,and 140 genera were observed.The estimated richness and diversity indices were both higher in each season.The composition and dominant picoeukaryotes changed significantly at the class level with the seasons alternating.Basidiomycota,Ciliophora,Ascomycota and Cryptomonadales were observed throughout the year.The Linear Discriminant Analysis(LDA)revealed the predominant discriminant taxa of four seasonal groups.Redundancy analysis(RDA)showed that NO2^−and salinity played very important roles to picoeukaryotes for all the spring samples and DS5 sample in winter,PO4^3−and pH affected mostly picoeukaryotes for winter samples and autumn samples.展开更多
The reactions of 18-crown-6with Na 2M(SCN)4(M=Pd,Pt )were studied and the complexNa (18-C-62 (H2O) nPd(SCN)4 n and complex2Na (18-C-6) 2 (H 2 O nPt (SCN) 4 n were characterized by ele-mental analysis,IR and X-ray diff...The reactions of 18-crown-6with Na 2M(SCN)4(M=Pd,Pt )were studied and the complexNa (18-C-62 (H2O) nPd(SCN)4 n and complex2Na (18-C-6) 2 (H 2 O nPt (SCN) 4 n were characterized by ele-mental analysis,IR and X-ray diffra ction analysis.The complexes belon g to monoclinic,space group P2 1 /n with cell dimensions,1:a=1.05734(7),b=1.42250(10),c=1.47762(10)nm,β=107.5330(10)°,V=2.1192(2)nm 3 ,Z =2,D calcd =1.460g·cm -3 ,F(000)=964,R 1 =0.0406,w R 2 =0.1264and2:a=1.05985(19),b=1.4237(3),c=1.4744(3)nm,β=107.096(3)°,V=2.1264(7)nm 3 ,Z =2,D calcd =1.690g·cm -3 ,F(000)=1028,R 1 =0.0292,w R 2 =0.0859.In the solid state,the comp lexes1and2show an one-dimensnal chain ofNa (18-C-6)狚 2 (H 2O)2+ complex cations andM(SCN) 4 2- (M=Pd,Pt )complex anions bridged by Na-N in-teractions.展开更多
基金the National Key Research and Development Program(MOST 2022YFA1602303 and MOST 2023YFA1606404)the National Natural Science Foundation of China(Nos.12347106,2147101,11925502,11935001 and 11961141003)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34030000).
文摘The recently discovered,extremely proton-rich nuclide 18 Mg exhibits ground-state decay via two sequential two-proton(2p)emissions through the intermediate nucleus,16Ne.This study investigates the structure and the initial 2p decay mechanism of^(18)Mgby examining the density and correlations of the valence protons using a three-body Gamow coupled-channel method.The results show that the ground state of^(18)Mgis significantly influenced by the continuum,resulting in a significant s-wave component.However,based on the current framework,this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the 18Mg-18C pair.Additionally,the time evolution analysis of the^(18)Mgground state suggests a simultaneous 2p emission during the first step of decay.The observed nucleon-nucleon correlations align with those of the light-mass 2p emitters,indicating a consistent decay behavior within this nuclear region.
基金Project supported by the Natural Science Foundation of Anhui Province(Grant No.1908085MA12)the National Natural Science Foundation of China(Grant No.21703222)。
文摘Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.
基金This project was supported by the Natural Science Foundation of Shandong Province (No.Y2003 D01)
文摘3,3′-Dimethyl-dibenzo-18-crown-6 was synthesized and characterized by elemental analysis, FT-IR, ^1H NMR, UV, MS spectra and X-ray single-crystal diffraction. It belongs to orthorhombic, space group Pna21 with a = 8.0790（18）, b = 16.780（4）, c = 15.222（3） .A, Z= 4, V= 2063.6（8） A3 Dc = 1.250 g/cm^3,μ = 0.090 mm^-1, F（000） = 832, R = 0.0474 and wR = 0.1103. According to structural analysis, the title compound possesses a boat-like configuration.
基金supported by the Bio&Medical Technology Development Program of the National Research Foundation of Korea(NRF)grant(No.2012M3A9C6049935)the DGIST Convergence Science Center Program(15-BD-04)of the Ministry of Science,ICT and Future Planning of Korea
文摘The normal development and optimal functioning of the brain requires a vigilant immune surveillance system to detect and remove potential risk factors and prevent infection and tissue damage. Microglia are the resident immune cells and the frontline defenders responsible for the immune response of the brain. Resting microglia possess a ramified morphology with numerous thin processes that continuously sample the environment. In response to inflammatory signals, microglia become activated and transform their morphology into a thick, amoeboid-like shape. Activated microglia proliferate, tolerate to sites of iniurv,
基金This project was supported by the Zhejiang Provincial Natural Science Foundation of China (R405066)
文摘The trinuclear complex bis（18-crown-6）thallium tetracyanoplatinate [Tl2（1 8-crown- 6）2Pt（CN）4]·2H2O was prepared and its structure was determined by X-ray diffraction analysis. The compound （C28H52N4O14PtTl2, Mr = 1272.57） crystallizes in monoclinic, space group P21/n with a = 10.5180（10）, b = 8.6162（8）, c = 21.118（2） A, β= 92.577（2）°, V= 1911.9（3） A^3, Z = 2, Dc = 2.211 g/cm^3, F（000） = 1200,μ= 12.123 mm^-1, R = 0.0181 and wR = 0.0427. The linearly arranged three metals are sandwiched by two 18-crown-6 molecules.
文摘The reactions of 18 crown 6 with each of K 2(M=Zn, Hg; mnt=1,2 dicyanoethene 1,2 dithiolate, C 2S 2(CN) 2- 2) were studied and novel complexes [K(18 C 6)] 2[Zn(mnt) 2](1) and [K(18 C 6)] 2[Hg(mnt) 2](2) were characterized by elemental analysis, IR spectrum and X ray diffraction analysis. Complex 1 displays a one dimensional chain of [K(18 C 6)] 2[Zn(mnt) 2] bridged by K O interactions between adjacent [K(18 C 6)] + units. Complex 2 is also a one dimensional chain of [K(18 C 6)] 2[Hg(mnt) 2] bridged by K...S weak interactions between adjacent [K(18 C 6)] + and [Hg(mnt) 2] 2- .
基金Supported by the National Natural Science foundation of China Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics, Academic Soinica, Wuhan
文摘Diaza Crown ethers are versatile complexing reagents, their complexing abilities are dramatically modified by the electron donating atoms on substituents attached to the nitrogen if they can give a three-dimensional cavity as in cryptates. Hence the synthesis and characterization of bibracchial lariat ethers (BIBLES) have received much attention. In the preparation of new BIBLES, a complex Ⅱ was unexpectedly obtained.
基金The project was supported by the Natural Science Foundation of Shandong Province (No. Z2004C06)National Basic Research Priority Program (2003CCA027)
文摘A novel derivative of glycyrrhetinic acid, （E）-ethyl 3-keto-18β-glycyrrhetinate 3- oxime C32H49NO4 （Mr = 511.72）, was synthesized and structurally characterized by IR, 1^H NMR and single-crystal X-ray diffraction. It belongs to monoclinic, space group P21, with a = 12.4897（12）, b = 7.3190（7）, c = 15.9944（14）A, β = 94.833（2）o, V = 1456.9（2）A^3, Z = 2, Dc = 1.167 g/cm^3, μ = 0.075 mm^-1, F（000） = 560, the final R = 0.0449 and wR = 0.1122. A total of 7486 reflections were collected, of which 2785 were independent （Rint = 0.0199） and 2605 were observed with I 〉 2σ（I）. There exists an intermolecular hydrogen bond which helps to stabilize the crystal structure.
文摘The structure of Na_2H_2[H_2V_2W_(18)O_(62)]12H_2O has been determined by x-ray analysis.The crystals are trigonal,space group R3m,with cell parameters a=37.613(11),c=12.972(7)A,V=15901(13)A^3,and Z=9.The structure model was refined by full-matrix least square to R=0.065 for 1702 reflections with F>4σ(F). The existence of the[H_2V_2W_(18)O_(62)]^(4-)heteropolyanion in the crystals has been confirmed.It is composed of two VO_4 tetrahedra and eighteen WO_6 octahedra linked to gve the Dawson-type structure.
文摘The title complex [K (dndb ) (H2O) (NCS ) ], (dndb = trans-dinitro-dibenzo-- 18 -- crown -- 6 -- ether ) crystallied in triclinic system, space group Pl wit h unit celldimensions a= 7. 844 (4), b= 11. 979(8), c= 14. 436(11) A; a= 75. 62(6), β=80. 15(5), γ= 71. 94(5)°, M.= 1131. 39, V= 1243(2) A3, Z= l, F(000) = 588, D.= 1. 511 g/cm3, μ= 10. 5 cm-l (MoKa). The final R= 0. 045 for 2740 observed reflections (I＞3σ). The title complex molecule is a dimer complex and the potassium(I) ionis nine--coordinated, being bonded to one NCS-- anion, one H2O molecule, six oxygenatoms of a crown ether ligand and an oxygen atom of a nitro of another crown ether ligand. The potassium(I) ion and the nine atoms bonded with it are all in two planeswhich are approximately vertical with each other. The trans--dinitro-- dibenzo-- 18 -- crown6 is a heptadentate ligand.
基金We thank the captain and all crews of the RV‘Zhehaiyan 2’for their assistance in sample collection.This work was supported by the Nonprofit Research Project of the State Oceanic Administration(Nos.201505025 and 201505003).
文摘Picoeukaryotes(<2-3μm)are major oceanic primary producers and play a crucial role for the functioning of marine ecosystems.However,the community structure of such communities remains poorly understood,especially in the East China Sea(ECS).We investigated the seasonal variations of abundance and diversity of picoeukaryotes,and recorded environmental variables,along a transect in Zhoushan Fishing Ground.High-throughput sequencing was used for sequencing the V4-V5 variable region within the 18S rRNA gene to analyze genetic diversity and relative abundance of picoeukaryotes.A total of 40 phyla,68 classes,99 orders,126 families,and 140 genera were observed.The estimated richness and diversity indices were both higher in each season.The composition and dominant picoeukaryotes changed significantly at the class level with the seasons alternating.Basidiomycota,Ciliophora,Ascomycota and Cryptomonadales were observed throughout the year.The Linear Discriminant Analysis(LDA)revealed the predominant discriminant taxa of four seasonal groups.Redundancy analysis(RDA)showed that NO2^−and salinity played very important roles to picoeukaryotes for all the spring samples and DS5 sample in winter,PO4^3−and pH affected mostly picoeukaryotes for winter samples and autumn samples.
文摘The reactions of 18-crown-6with Na 2M(SCN)4(M=Pd,Pt )were studied and the complexNa (18-C-62 (H2O) nPd(SCN)4 n and complex2Na (18-C-6) 2 (H 2 O nPt (SCN) 4 n were characterized by ele-mental analysis,IR and X-ray diffra ction analysis.The complexes belon g to monoclinic,space group P2 1 /n with cell dimensions,1:a=1.05734(7),b=1.42250(10),c=1.47762(10)nm,β=107.5330(10)°,V=2.1192(2)nm 3 ,Z =2,D calcd =1.460g·cm -3 ,F(000)=964,R 1 =0.0406,w R 2 =0.1264and2:a=1.05985(19),b=1.4237(3),c=1.4744(3)nm,β=107.096(3)°,V=2.1264(7)nm 3 ,Z =2,D calcd =1.690g·cm -3 ,F(000)=1028,R 1 =0.0292,w R 2 =0.0859.In the solid state,the comp lexes1and2show an one-dimensnal chain ofNa (18-C-6)狚 2 (H 2O)2+ complex cations andM(SCN) 4 2- (M=Pd,Pt )complex anions bridged by Na-N in-teractions.
