The microphase separation extent of biomedical segmented polyetherurethanes were greatly enhanced due to the presence of sulfoalkyl pendant groups contained in the hard segments,and the hard segments were more orderly...The microphase separation extent of biomedical segmented polyetherurethanes were greatly enhanced due to the presence of sulfoalkyl pendant groups contained in the hard segments,and the hard segments were more orderly aggregated through ionic interaction.展开更多
Specimens of Mugil soiuy were collected from the coastal waters of Bohai Sea in Tianjin. The gillfilaments were cut with fine scissors and soaked for 24h in a fixative consisting of 2.5% glutaralde-hyde in 0.1 mol lph...Specimens of Mugil soiuy were collected from the coastal waters of Bohai Sea in Tianjin. The gillfilaments were cut with fine scissors and soaked for 24h in a fixative consisting of 2.5% glutaralde-hyde in 0.1 mol lphosporic acid buffer. After three washes in a buffer solution the tissue was fixedin a mixture of 1% osmium tetraoxide at 4℃ for 1h. The tissue was dehydrated in graded ethandethanols and dried. The tissue was examined and photographed with an SEM at an accelerating voltage展开更多
The equilibrium geometries,excitation energies,force constants and vibrational frequencies for the low-ly- ing electronic states X ~2B_1,~2A_1,~2B_2 and ~2A_2 of the AsH_2 radical have been calculated at the MRSDCI le...The equilibrium geometries,excitation energies,force constants and vibrational frequencies for the low-ly- ing electronic states X ~2B_1,~2A_1,~2B_2 and ~2A_2 of the AsH_2 radical have been calculated at the MRSDCI level with a 3-21G~* basis set.Our calculated geometries,excitation enegies and vibional frequencies for the X ~2B_1 and ~2A_1 states are in good agreement with available experimental data.The electronic transition dipole mo- ments,oscillator strengths for the ~2A_1→X ~2B_1 and ~2A_2→X ~2B_1 transitions,radiative lifetimes for the ~2A_1 and ~2A_2 states are calculated based on the MRSDC^1 wavefunctions,predicting results in reasonable agreement with available experiment.展开更多
Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc(Sc_6Cl_(12)Co).Based on the analysis of the composition of the molecular orbitals and bond orders,it was ...Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc(Sc_6Cl_(12)Co).Based on the analysis of the composition of the molecular orbitals and bond orders,it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc- Cl is mainly ionic in character.There are nine valence molecular orbitals in the cluster.展开更多
The localized molecular orbitals for typical bowl-shaped circulenes are obtained by the use of INDO-LMO method. It is found that these bowl-shaped circulenes with strained π-electron systems are still aromatic and th...The localized molecular orbitals for typical bowl-shaped circulenes are obtained by the use of INDO-LMO method. It is found that these bowl-shaped circulenes with strained π-electron systems are still aromatic and the rim π-bonds with larger localization form reactive regions for formation of buckminsterfullerene.展开更多
Microwave electron cyclotron resonance plasma enhanced chemical vapor depositionwas used to grow silicon dioxide films on crystalline silicon substrate for planar optical waveguides.The relationship between plasma par...Microwave electron cyclotron resonance plasma enhanced chemical vapor depositionwas used to grow silicon dioxide films on crystalline silicon substrate for planar optical waveguides.The relationship between plasma parameters and deposition rates was investigated, and the influ-ence of radio frequency substrate bias on properties of SiO2 films was also preliminarily studied.X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron mi-croscopy, atomic force microscopy and elllipsometry were used to characterize the deposited films,showing that SiO2 films with good structural and optical properties prepared at low temperaturehave been achieved. They can basically meet the requirements of integrated optical waveguides.展开更多
Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graph...Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graphene-based electronic double-layer structures, revealing giant yet reproducible drag fluctuations at cryogenic temperatures. These fluctuations' characteristics, including amplitude and peak/valley spacing, are mainly determined by the drag layer's carrier dynamics rather than the drive layer's, resulting in violation of the Onsager reciprocity relation. Notably, the drag fluctuations remain observable up to 35 K, far exceeding universal conductance fluctuations within individual layers. This suggests enhanced phase coherence in inter-layer drag compared to single-layer transport, as further confirmed by quantitative analysis of auto-correlation fields of fluctuations under magnetic fields. Our findings provide new insights into quantum interference effects and their interplay with Coulomb interactions in solids. The observations of significant drag fluctuations could potentially help address chaotic signals between nearby components in nanoscale devices.展开更多
Attosecond light pulses have revolutionized the study of electron dynamics in materials by enabling the observation of ultrafast processes with unprecedented attosecond temporal resolution.They are primarily generated...Attosecond light pulses have revolutionized the study of electron dynamics in materials by enabling the observation of ultrafast processes with unprecedented attosecond temporal resolution.They are primarily generated through the process of high-order harmonic generation.This paper presents a comprehensive setup for attosecond pulse generation and measurement.Using a 900 nm,7 mJ,and 7 fs femtosecond laser with stabilized carrier-envelope phase,we employ polarization gating to generate a near single-cycle,linearly polarized pulse that interacts with neon gas to produce a broadband extreme-ultraviolet continuum with a cutoff photon energy of∼120 eV.The temporal and spectral characteristics of the generated single attosecond pulses are measured using an attosecond streak camera,and the pulse duration is determined to be 59 as through the frequency-resolved optical gating for complete reconstruction of attosecond bursts retrieval algorithm.As part of the Synergetic Extreme Condition User Facility,this setup will facilitate ultrafast research in transient absorption and photoelectron spectroscopy,providing global users with a powerful tool for studying electron dynamics in various materials.展开更多
Ultrastructure of Kupffer cells and hepatocytes in liver bioptate was evaluated in a 17-year-old boy with Dubin -Johnson syndrome （D.1S）. The liver tissue obtained by needle biopsy was fixed in glutaraldehyde and pa...Ultrastructure of Kupffer cells and hepatocytes in liver bioptate was evaluated in a 17-year-old boy with Dubin -Johnson syndrome （D.1S）. The liver tissue obtained by needle biopsy was fixed in glutaraldehyde and paraformaldehyde and routinely processed for electron microscopic analysis. The ultrastructural examinations of liver bioptate revealed the accumulation of membranebound, electron-dense lysosomal granules within the cytoplasm of hepatocytes, characteristic of D.1S. They were located mainly in the vicinity of the biliary pole, and preferentially in the centrilobular region that corresponded to the pigment deposits seen under light microscope. The presence of the granules was accompanied by dilated elements of the granular endoplasmic reticulum and paracrystalline mitochondrial inclusions as well as dilation of the bile canaliculi. The changes in hepatocytes coexisted with marked stimulation and enhanced phagocytic activity of Kupffer cells. This was manifested in the accumulation of pigment deposits within their cytoplasm that corresponded to those observed in hepatocytes. Hyperactive pericentral Kupffer cells which are involved in the response to pigmentary material originating from disintegrated hepatocytes may play an essential role in the development of DJS.展开更多
The canonical and locatized molecutar orbiters of [NCCuS_2NoS_2]^(2-) cluster were calculated by means of CNDO quantum chemistry method. Then the energy and properties of corresponding chemicat bonds were discussed, e...The canonical and locatized molecutar orbiters of [NCCuS_2NoS_2]^(2-) cluster were calculated by means of CNDO quantum chemistry method. Then the energy and properties of corresponding chemicat bonds were discussed, especially, Cu-Sb-No three center conjugated π bonds and No-St-No conjugated π bonds were accounted for.展开更多
Combining analytical transmission electron microscopy systematic tilting, scanning transmission electron microscopy mapping and nano-beam electron diffraction operations, we obtain direct experimental proofs on the bo...Combining analytical transmission electron microscopy systematic tilting, scanning transmission electron microscopy mapping and nano-beam electron diffraction operations, we obtain direct experimental proofs on the boundary type, elemental distribution and structure of the cellular reerystallization reaction front for a single- crystal superalloy. It is demonstrated that the cellular recrystallization reaction front usually corresponds to coincidence site lattice boundaries, and a thin layer of γ-forming elements such as Re, Cr, Mo and Co invariably exists in the direct reaction front. Furthermore, the thin layer with γ-forming elements is proved to be γ phase, with the same orientation as the neighboring original matrix.展开更多
Ab initio electronic structure calculations are reported for low-lying electronic states,X ~1Σ^+and A ~1Π of the N_2F^+ molecule.Geometric parameters for the ground state X ~1Σ^+ are predicted by means of mul- tire...Ab initio electronic structure calculations are reported for low-lying electronic states,X ~1Σ^+and A ~1Π of the N_2F^+ molecule.Geometric parameters for the ground state X ~1Σ^+ are predicted by means of mul- tireference single and double excitation configuration interaction(MRSDCI)calculations with a double zeta plus polarization(DZ+P)basis set.Vertical excitation energy for these two electronic states is determined using MRSDCI/DZ+P calculations at the ground state equilibrium geometry.The oscillator strength for the X^1Σ+→ A ~1Π transition and the radiative lifetime for the A^1Π state are calculated based on the MRSDCI wavefunc- tions.展开更多
Cases report Case 1: A 50-year-old man was injuried by iron filings on his left eye. He was admitted to our hospital on Feb. 3, 1987. On examination, his visual acuity was 20/15 OD and 20/500 OS. Left eye: The cornea ...Cases report Case 1: A 50-year-old man was injuried by iron filings on his left eye. He was admitted to our hospital on Feb. 3, 1987. On examination, his visual acuity was 20/15 OD and 20/500 OS. Left eye: The cornea was clear, the anterior chamber depth was 3 CT, tyndall(-). Iris pattern is clear, pupil was 3.5×3.5mm. Dilated pupil examination: There were scattered brown-yellow ironrust under anterior capsule and the lens cortex had become totally opaque. Nuclear, posterior capsule and fundus can't be ...展开更多
The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln ...The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln and N-Ln,5d orbitals of Ln have large contribution in all valence orbitals of Ln and 4f orbitals have very small contribution.(2)The covalent chara- cter and ionic character are almost equal in the chemical bond which is comparatively weak between phen,C_2H_5OH and Ln are mainly ionic with some covalent character.展开更多
The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It ...The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It has been found that both singlet oxygen and free radical mechanisms exist simultaneously in primary photochemical reactions, and there is a competition between both mechanisms. When the oxygen concentration in solutions comes down to 12-14% of the stanting level, the predominant mechanism can be changed from the singlet oxygen to the free radical.Whether HPD exists in aggregation state is very important to photosensitization mechanisms.In the presence of the aggregation state of HPD, the predominant mechanism is the free radical,and photosensitization effects of HPD are all the better.展开更多
The electronic structures of six cubane-like cluster compounds of the type[Fe_4S_4L_4]~n (L=SH,OH,and CI,n=-2 and -3;L=NO,n=0 and -1)have been calculated by using DV-X_α method,and the bonding properties are discusse...The electronic structures of six cubane-like cluster compounds of the type[Fe_4S_4L_4]~n (L=SH,OH,and CI,n=-2 and -3;L=NO,n=0 and -1)have been calculated by using DV-X_α method,and the bonding properties are discussed with emphasis on the ligand effect on cluster bonding. The comparisons of MO energies and cluster charge distributions with the experimental data are made, and the differences between the early studies and the present one are also briefly commented.展开更多
An attosecond light source provides an advanced tool for investigating electron motion using time-resolvedspectroscopy techniques.Isolated attosecond pulses,especially,will significantlyadvance the study of electron d...An attosecond light source provides an advanced tool for investigating electron motion using time-resolvedspectroscopy techniques.Isolated attosecond pulses,especially,will significantlyadvance the study of electron dynamics.However,achieving high-intensity isolated attosecond pulses is still challenging at the present stage.In this paper,we propose a novel scheme for generating high-intensity,isolated attosecond soft x-ray free-electron lasers(FELs)using a mid-infrared(MiR)subcycle modulation laser from gas-filled hollow capillary fibers.The multi-cycle MlR pulses are first compressed to subcycles using a krypton-filled hollow capillary fiber with a decreasing pressure gradient due to the soliton self-compression effect.By utilizing such subcycle MlR laser pulses to modulate an electron beam,we can obtain a quasi-isolated current peak,which can then produce an isolated FEL pulse with a high signal-to-noise ratio,naturally synchronizing with the subcycle MiR laser pulse.Numerical simulations have been carried out,including subcycle pulse generation,electron beam modulation,and FEL radiation processes.The simulation results indicate that an isolated attosecond pulse with a wavelength of 1 nm,a peak power of~28 GW,a pulse duration of~580 as,and a signal-to-noise ratio of~96.2%can be generated by our proposed method.The numerical results demonstrated here pave a new way for generating a high-intensity isolated attosecond soft x-ray pulse,which may have many applications in nonlinear spectroscopy and atomic-site electronic processes.展开更多
Electron microscopic autoradiographic studies on the dynamics and location of DNAsynthesis by means of incorporation of ~8H-thymidine during the replication of duck plaguevirus (DPV) revealed that the duration of DNA ...Electron microscopic autoradiographic studies on the dynamics and location of DNAsynthesis by means of incorporation of ~8H-thymidine during the replication of duck plaguevirus (DPV) revealed that the duration of DNA synthesis of DPV was rather long. The repli-cation of viral DNA occurred simultaneously with the assembly procedure of nucleocapsids, thematuration and release of viruses. DNA synthesis of DPV occurred in the matrix with lowerelectron density in the nucleus. The replicated viral DNA accumulated in the viroplast With highelectron density where the assembly of nucleocapsids occurred. The viroplast with high electrondensity was not the region of viral DNA synthesis.展开更多
An ab initio calculation was performed on the electronic structures of MoS,MoS_4^(2-) and Mo_2S_2 using relativistic effective core potential(RECP)for molybdenum,and non-relativistic ECP for sulfur.We predicted that t...An ab initio calculation was performed on the electronic structures of MoS,MoS_4^(2-) and Mo_2S_2 using relativistic effective core potential(RECP)for molybdenum,and non-relativistic ECP for sulfur.We predicted that the equilibrium bond length and the dissociation energy of MoS in ground state are 3.89 a.u.and 4.67 eV,respectively,and that the bond is a triple-bond.The ground state of MoS_4^(2-) in Td symmetry is ~1A_1 and π-bonding dominates σ-donation in the molybdenum- sulfur interaction.The Mo_2S_2 is a model contracted from bi-nuclear sulfur-bridged clusters,and the bonding orbitals 1 b_(1u),1b_1g and 1b_2g make the dominant contribution to the stabilization of sulfur- bridged species.展开更多
文摘The microphase separation extent of biomedical segmented polyetherurethanes were greatly enhanced due to the presence of sulfoalkyl pendant groups contained in the hard segments,and the hard segments were more orderly aggregated through ionic interaction.
文摘Specimens of Mugil soiuy were collected from the coastal waters of Bohai Sea in Tianjin. The gillfilaments were cut with fine scissors and soaked for 24h in a fixative consisting of 2.5% glutaralde-hyde in 0.1 mol lphosporic acid buffer. After three washes in a buffer solution the tissue was fixedin a mixture of 1% osmium tetraoxide at 4℃ for 1h. The tissue was dehydrated in graded ethandethanols and dried. The tissue was examined and photographed with an SEM at an accelerating voltage
文摘The equilibrium geometries,excitation energies,force constants and vibrational frequencies for the low-ly- ing electronic states X ~2B_1,~2A_1,~2B_2 and ~2A_2 of the AsH_2 radical have been calculated at the MRSDCI level with a 3-21G~* basis set.Our calculated geometries,excitation enegies and vibional frequencies for the X ~2B_1 and ~2A_1 states are in good agreement with available experimental data.The electronic transition dipole mo- ments,oscillator strengths for the ~2A_1→X ~2B_1 and ~2A_2→X ~2B_1 transitions,radiative lifetimes for the ~2A_1 and ~2A_2 states are calculated based on the MRSDC^1 wavefunctions,predicting results in reasonable agreement with available experiment.
文摘Spin-unrestricted localized INDO method was used to calculate the electronic structure of rare earth cluster Sc(Sc_6Cl_(12)Co).Based on the analysis of the composition of the molecular orbitals and bond orders,it was pointed out that the interstitial transition metal atom Co in the octahedral Sc skeleton forms strong covalent bond with six Sc atoms and the bonding of Sc- Cl is mainly ionic in character.There are nine valence molecular orbitals in the cluster.
文摘The localized molecular orbitals for typical bowl-shaped circulenes are obtained by the use of INDO-LMO method. It is found that these bowl-shaped circulenes with strained π-electron systems are still aromatic and the rim π-bonds with larger localization form reactive regions for formation of buckminsterfullerene.
文摘Microwave electron cyclotron resonance plasma enhanced chemical vapor depositionwas used to grow silicon dioxide films on crystalline silicon substrate for planar optical waveguides.The relationship between plasma parameters and deposition rates was investigated, and the influ-ence of radio frequency substrate bias on properties of SiO2 films was also preliminarily studied.X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron mi-croscopy, atomic force microscopy and elllipsometry were used to characterize the deposited films,showing that SiO2 films with good structural and optical properties prepared at low temperaturehave been achieved. They can basically meet the requirements of integrated optical waveguides.
基金supported by the National Natural Science Foundation of China (Grant Nos.12474051 and 92165201)the Chinese Academy of Sciences Project for Young Scientists in Basic Research (Grant No.YSBR-046)+1 种基金the National Key Research and Development Program of China (Grant No.2023YFA1406300)the Anhui Provincial Natural Science Foundation (Grant Nos.2308085J11 and2308085QA14)。
文摘Recent advances in two-dimensional layered systems have greatly enriched electronic transport studies, particularly in inter-layer Coulomb drag research. Here, systematic transport measurements were conducted in graphene-based electronic double-layer structures, revealing giant yet reproducible drag fluctuations at cryogenic temperatures. These fluctuations' characteristics, including amplitude and peak/valley spacing, are mainly determined by the drag layer's carrier dynamics rather than the drive layer's, resulting in violation of the Onsager reciprocity relation. Notably, the drag fluctuations remain observable up to 35 K, far exceeding universal conductance fluctuations within individual layers. This suggests enhanced phase coherence in inter-layer drag compared to single-layer transport, as further confirmed by quantitative analysis of auto-correlation fields of fluctuations under magnetic fields. Our findings provide new insights into quantum interference effects and their interplay with Coulomb interactions in solids. The observations of significant drag fluctuations could potentially help address chaotic signals between nearby components in nanoscale devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174435,12034020,and 92250303)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-091)the National Key R&D Program of China(Grant No.2022YFA1604200).
文摘Attosecond light pulses have revolutionized the study of electron dynamics in materials by enabling the observation of ultrafast processes with unprecedented attosecond temporal resolution.They are primarily generated through the process of high-order harmonic generation.This paper presents a comprehensive setup for attosecond pulse generation and measurement.Using a 900 nm,7 mJ,and 7 fs femtosecond laser with stabilized carrier-envelope phase,we employ polarization gating to generate a near single-cycle,linearly polarized pulse that interacts with neon gas to produce a broadband extreme-ultraviolet continuum with a cutoff photon energy of∼120 eV.The temporal and spectral characteristics of the generated single attosecond pulses are measured using an attosecond streak camera,and the pulse duration is determined to be 59 as through the frequency-resolved optical gating for complete reconstruction of attosecond bursts retrieval algorithm.As part of the Synergetic Extreme Condition User Facility,this setup will facilitate ultrafast research in transient absorption and photoelectron spectroscopy,providing global users with a powerful tool for studying electron dynamics in various materials.
文摘Ultrastructure of Kupffer cells and hepatocytes in liver bioptate was evaluated in a 17-year-old boy with Dubin -Johnson syndrome （D.1S）. The liver tissue obtained by needle biopsy was fixed in glutaraldehyde and paraformaldehyde and routinely processed for electron microscopic analysis. The ultrastructural examinations of liver bioptate revealed the accumulation of membranebound, electron-dense lysosomal granules within the cytoplasm of hepatocytes, characteristic of D.1S. They were located mainly in the vicinity of the biliary pole, and preferentially in the centrilobular region that corresponded to the pigment deposits seen under light microscope. The presence of the granules was accompanied by dilated elements of the granular endoplasmic reticulum and paracrystalline mitochondrial inclusions as well as dilation of the bile canaliculi. The changes in hepatocytes coexisted with marked stimulation and enhanced phagocytic activity of Kupffer cells. This was manifested in the accumulation of pigment deposits within their cytoplasm that corresponded to those observed in hepatocytes. Hyperactive pericentral Kupffer cells which are involved in the response to pigmentary material originating from disintegrated hepatocytes may play an essential role in the development of DJS.
文摘The canonical and locatized molecutar orbiters of [NCCuS_2NoS_2]^(2-) cluster were calculated by means of CNDO quantum chemistry method. Then the energy and properties of corresponding chemicat bonds were discussed, especially, Cu-Sb-No three center conjugated π bonds and No-St-No conjugated π bonds were accounted for.
基金Supported by the Scientific Research Foundation of Xi’an University of Technology under Grant No 101-451115007the National Natural Science Foundation of China under Grant No 51174161the Pivot Innovation Team of Shaanxi Electric Materials and Infiltration Technique under Grant No 2012KCT-25
文摘Combining analytical transmission electron microscopy systematic tilting, scanning transmission electron microscopy mapping and nano-beam electron diffraction operations, we obtain direct experimental proofs on the boundary type, elemental distribution and structure of the cellular reerystallization reaction front for a single- crystal superalloy. It is demonstrated that the cellular recrystallization reaction front usually corresponds to coincidence site lattice boundaries, and a thin layer of γ-forming elements such as Re, Cr, Mo and Co invariably exists in the direct reaction front. Furthermore, the thin layer with γ-forming elements is proved to be γ phase, with the same orientation as the neighboring original matrix.
文摘Ab initio electronic structure calculations are reported for low-lying electronic states,X ~1Σ^+and A ~1Π of the N_2F^+ molecule.Geometric parameters for the ground state X ~1Σ^+ are predicted by means of mul- tireference single and double excitation configuration interaction(MRSDCI)calculations with a double zeta plus polarization(DZ+P)basis set.Vertical excitation energy for these two electronic states is determined using MRSDCI/DZ+P calculations at the ground state equilibrium geometry.The oscillator strength for the X^1Σ+→ A ~1Π transition and the radiative lifetime for the A^1Π state are calculated based on the MRSDCI wavefunc- tions.
文摘Cases report Case 1: A 50-year-old man was injuried by iron filings on his left eye. He was admitted to our hospital on Feb. 3, 1987. On examination, his visual acuity was 20/15 OD and 20/500 OS. Left eye: The cornea was clear, the anterior chamber depth was 3 CT, tyndall(-). Iris pattern is clear, pupil was 3.5×3.5mm. Dilated pupil examination: There were scattered brown-yellow ironrust under anterior capsule and the lens cortex had become totally opaque. Nuclear, posterior capsule and fundus can't be ...
文摘The electronic structure and chemical bonding of the title comp- lexes have been studied by an unrestricted INDO program made applicable for the lanthanoid compounds.The results indicated:(1)In coordinated bonds O-Ln and N-Ln,5d orbitals of Ln have large contribution in all valence orbitals of Ln and 4f orbitals have very small contribution.(2)The covalent chara- cter and ionic character are almost equal in the chemical bond which is comparatively weak between phen,C_2H_5OH and Ln are mainly ionic with some covalent character.
文摘The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It has been found that both singlet oxygen and free radical mechanisms exist simultaneously in primary photochemical reactions, and there is a competition between both mechanisms. When the oxygen concentration in solutions comes down to 12-14% of the stanting level, the predominant mechanism can be changed from the singlet oxygen to the free radical.Whether HPD exists in aggregation state is very important to photosensitization mechanisms.In the presence of the aggregation state of HPD, the predominant mechanism is the free radical,and photosensitization effects of HPD are all the better.
基金This work is financially supported by the National Natural Science Foundation of China.
文摘The electronic structures of six cubane-like cluster compounds of the type[Fe_4S_4L_4]~n (L=SH,OH,and CI,n=-2 and -3;L=NO,n=0 and -1)have been calculated by using DV-X_α method,and the bonding properties are discussed with emphasis on the ligand effect on cluster bonding. The comparisons of MO energies and cluster charge distributions with the experimental data are made, and the differences between the early studies and the present one are also briefly commented.
基金supported by the National Natural Science Foundation of China(Nos.12435011,11905275,11775294,12122514,and 62205353)the Youth Innovation Promotion Association CAS,the National Postdoctoral Program for Innovative Talents(No.BX2021328)+1 种基金the China Postdoctoral Science Foundation(No.2021M703325)the CAS Project for Young Scientists in Basic Research(YSBR-115).
文摘An attosecond light source provides an advanced tool for investigating electron motion using time-resolvedspectroscopy techniques.Isolated attosecond pulses,especially,will significantlyadvance the study of electron dynamics.However,achieving high-intensity isolated attosecond pulses is still challenging at the present stage.In this paper,we propose a novel scheme for generating high-intensity,isolated attosecond soft x-ray free-electron lasers(FELs)using a mid-infrared(MiR)subcycle modulation laser from gas-filled hollow capillary fibers.The multi-cycle MlR pulses are first compressed to subcycles using a krypton-filled hollow capillary fiber with a decreasing pressure gradient due to the soliton self-compression effect.By utilizing such subcycle MlR laser pulses to modulate an electron beam,we can obtain a quasi-isolated current peak,which can then produce an isolated FEL pulse with a high signal-to-noise ratio,naturally synchronizing with the subcycle MiR laser pulse.Numerical simulations have been carried out,including subcycle pulse generation,electron beam modulation,and FEL radiation processes.The simulation results indicate that an isolated attosecond pulse with a wavelength of 1 nm,a peak power of~28 GW,a pulse duration of~580 as,and a signal-to-noise ratio of~96.2%can be generated by our proposed method.The numerical results demonstrated here pave a new way for generating a high-intensity isolated attosecond soft x-ray pulse,which may have many applications in nonlinear spectroscopy and atomic-site electronic processes.
文摘Electron microscopic autoradiographic studies on the dynamics and location of DNAsynthesis by means of incorporation of ~8H-thymidine during the replication of duck plaguevirus (DPV) revealed that the duration of DNA synthesis of DPV was rather long. The repli-cation of viral DNA occurred simultaneously with the assembly procedure of nucleocapsids, thematuration and release of viruses. DNA synthesis of DPV occurred in the matrix with lowerelectron density in the nucleus. The replicated viral DNA accumulated in the viroplast With highelectron density where the assembly of nucleocapsids occurred. The viroplast with high electrondensity was not the region of viral DNA synthesis.
文摘An ab initio calculation was performed on the electronic structures of MoS,MoS_4^(2-) and Mo_2S_2 using relativistic effective core potential(RECP)for molybdenum,and non-relativistic ECP for sulfur.We predicted that the equilibrium bond length and the dissociation energy of MoS in ground state are 3.89 a.u.and 4.67 eV,respectively,and that the bond is a triple-bond.The ground state of MoS_4^(2-) in Td symmetry is ~1A_1 and π-bonding dominates σ-donation in the molybdenum- sulfur interaction.The Mo_2S_2 is a model contracted from bi-nuclear sulfur-bridged clusters,and the bonding orbitals 1 b_(1u),1b_1g and 1b_2g make the dominant contribution to the stabilization of sulfur- bridged species.
