The singlet-triplet splitting energy gap ΔEs-T= Es - ET is calculated for the ortho-, meta-, and para-xylylenes and their heteroatomic analogous by means of AM1-CI approach. It is shownthat when the radical centers R...The singlet-triplet splitting energy gap ΔEs-T= Es - ET is calculated for the ortho-, meta-, and para-xylylenes and their heteroatomic analogous by means of AM1-CI approach. It is shownthat when the radical centers R(R=H2C- ,H2N+- or HN’- ) are twisted sufficiently far out ofconjugation with the benzene ring, ΔEs-T tends to zero or is negative, i.e. ortho-, meta-, and para-phenylenes turn into weak ferromagnetic or antiferromagnetic coupling unit, while they are strong ferromagnetic (meta-isomers) or antiferromagnetic (ortho-, para-isomers) coupling units under planar conformation. It is suggested that serious twisted conformation is not recommended candidate for the design of novel high-spin molecules with stable high-spin ground states by ortho-or para-phenylene coupling unit.展开更多
Dinuclear copper complex with biradicals [Cu(hfac)2]2PhBNM(PhBNM = 2,5-bimethyl-1,4-bis(4,4,5,5-tetramethyllimidazoline-1-oxyl-3-oxide)phenyl,hfac=hexafluoroacetylacetonate) has been synthesized and characterized. It ...Dinuclear copper complex with biradicals [Cu(hfac)2]2PhBNM(PhBNM = 2,5-bimethyl-1,4-bis(4,4,5,5-tetramethyllimidazoline-1-oxyl-3-oxide)phenyl,hfac=hexafluoroacetylacetonate) has been synthesized and characterized. It crystallized in the monoclinic system, with space group C2/c, a=1.9012(4), b=1.3718(3), c=2.1620(4) nm, β=97.55(3)°, Z=4. The X-ray structure analysis shows that the molecular structure consists of two kinds of conformations. The ratio of them is 7:3. The energy of two conformations, calculated with molecular mechanics, are different, E1=740 kJ/mol, and E2=771 kJ · mol-1. The CNDO/k results on the complex indicate that the orbital energy of low spin state is lower than that of high spin state, which correspond with the results of magnetic measurement.展开更多
Photochromism due to organometallic ring-closure through C−C linkage has never been attained.In this work,we report a preliminary approach to achieve T-type photochromism by creating a metallacyclopentadiene biradical...Photochromism due to organometallic ring-closure through C−C linkage has never been attained.In this work,we report a preliminary approach to achieve T-type photochromism by creating a metallacyclopentadiene biradical under light irradiation.A class of CuPt2 phenylacetylide compounds was prepared with distinguished photochromic recyclability and durability,which involved the formation of thermally sensitive copper(I)-butadienyl,five-membered ring through copper(I)-participated ring-closure.Upon UV light irradiation,the metallacyclopentadiene with copper(I)center chelated by 1,3-butadiene-1,4-diyl biradical was generated through photochemical C-C linkage of two face-to-face oriented ethynyl units in close proximity,giving rise to a drastic change in UV-vis absorption spectrum.When UV light irradiation was ceased,decoloration occurred through thermal cycloreversion,which endowed the photochromic CuPt2 complexes with self-recovery characteristics.Electron paramagnetic resonance(EPR)spectral study confirmed a biradical feature of a ring-closed isomer.The thermal decoloration half-lives at ambient temperature were regulated from seconds to hours by increasing F substituents in phenylethynyl ligands.展开更多
Five novel complexes of formula [Ln(hfac)3] · BNPhOM, where La = Gd, Ho, Dy, Y, Er; Mac = hexfluoracetylacetonate; BNPhOM=1,3-[bis-2,2′,-(4,4,5,5-tetramethyl-4,5-di-hydro-1H-imidazolyl-1-oxyl-3-oxide) phenoxy] p...Five novel complexes of formula [Ln(hfac)3] · BNPhOM, where La = Gd, Ho, Dy, Y, Er; Mac = hexfluoracetylacetonate; BNPhOM=1,3-[bis-2,2′,-(4,4,5,5-tetramethyl-4,5-di-hydro-1H-imidazolyl-1-oxyl-3-oxide) phenoxy] propane, have been prepared and characterized by elemental analysis, molar conductances, IR and electronic spectra. The temperature dependence of the magnetic susceptibility for Gd(III) and radical was measured (2—-300 K). The observed data were successfully simulated giving the exchange integral J = 0.28 cm?1, J' = - 0.33 cm?1. These results indicate a weak ferromagnetic spin exchange interaction between Gd(III) ion and the radical and a weak antiferromagnetic spin exchange interaction between the radical and radical.展开更多
Novel stable high-spin molecules possessing three different arranging fashions were designed with —^＊N—S— as a spin-containing （SC） fragment, an aromatic group, such as benzene （ 1 ）, pyridine （2）, pyridazi...Novel stable high-spin molecules possessing three different arranging fashions were designed with —^＊N—S— as a spin-containing （SC） fragment, an aromatic group, such as benzene （ 1 ）, pyridine （2）, pyridazine （3） , pyrimidine （4）, pyrazine （5） or triazine （6） as end groups （EG）, and phenyl as a ferromagnetic coupling （FC） unit. The effects of different EG on the spin multiplicities of the ground states and their stabilities were investigated by means of the AM1-CI approach. All the investigated molecules corresponded to the FC and possessed high-spin ground states. The spin on the two atoms of the SC fragment was not in agreement with the delocalization results in the specific stability of —^＊N—S—. In those molecules, the stabilities of the triplet states decreased when the distance between the atoms of central SC fragments （—N—） increased. The stabilities of the triplet states of compounds 1a-n, 1b-n and 1c-n, with heterocycles as EG were higher than those of the triplet states of those compounds with phenyl as EG. Furthermore, the stahilities of the triplet states of the compounds with pyrimidine and triazine as EG were higher than those with pyridine, pyridazine or pyrasine as EG.展开更多
Novel stable high spin molecules possessing three different arranged fashions are designed with - · N-N< as a spin-containing(SC) fragment, phenylene as an end group and various aromatic molecules, such as ben...Novel stable high spin molecules possessing three different arranged fashions are designed with - · N-N< as a spin-containing(SC) fragment, phenylene as an end group and various aromatic molecules, such as benzene(1), 2,6-pyridine(2), 3,5-pyridine(3), pyridazine(4), 4,6-pyrimidine(5), 2,6-pyrimidine(6), pyrazine(7) and triazine(8), as a ferromagnetic coupling(FC) unit. The effects of the different coupling units on the spin multiplicities of the ground states and their stabilities were investigated by means of AM1-CI approach. It has been found that the spin densities on the two atoms of the SC fragment are different from delocalization results in the specific stability of - · N-N<. In these molecules, the stabilities of the triplet states decrease when the distance between the atoms of central SC(-N-) increases. It is shown that the heterocycles as the coupling units have influence on the stabilities of the high-spin ground states. That the heteroatom lying in m -phenyl can improve ferromagnetic coupling, while the heteroatom lying in o -phenyl or p -phenyl is not in favor of the ferromagnetic coupling.展开更多
The series of biradicals with m phenylene coupling unit and hetero spin centers were calculated compared with those possessing homo spin centers using AM1 CI method. A simple rule was proposed to design high s...The series of biradicals with m phenylene coupling unit and hetero spin centers were calculated compared with those possessing homo spin centers using AM1 CI method. A simple rule was proposed to design high spin molecules with ferromagnetic coupling unit and hetero spin centers. Two neutral (or charged) hetero spin centers resulted in high spin ground state, one neutral and another charged hetero spin centers correspond to low spin ground state. The latter was ascribed to the huge splitting of two partially occupied molecular orbitals.展开更多
Breast cancer(BC)is the most common cause of women’s deaths worldwide.The mammography technique is the most important modality for the detection of BC.To detect abnormalities in mammographic images,the Breast Imaging...Breast cancer(BC)is the most common cause of women’s deaths worldwide.The mammography technique is the most important modality for the detection of BC.To detect abnormalities in mammographic images,the Breast Imaging Reporting and Data System(BI-RADs)is used as a baseline.The correct allocation of BI-RADs categories for mammographic images is always an interesting task,even for specialists.In this work,to detect and classify the mammogram images in BI-RADs,a novel hybrid model is presented using a convolutional neural network(CNN)with the integration of a support vector machine(SVM).The dataset used in this research was collected from different hospitals in the Qassim health cluster of Saudi Arabia.The collection of all categories of BI-RADs is one of the major contributions of this paper.Another significant contribution is the development of a hybrid approach through the integration of CNN and SVM.The proposed hybrid approach uses three CNN models to obtain ensemble CNN model results.This ensemble model saves the values to integrate them with SVM.The proposed system achieved a classification accuracy,sensitivity,specificity,precision,and F1-score of 93.6%,94.8%,96.9%,96.6%,and 95.7%,respectively.The proposed model achieved better performance compared to previously available methods.展开更多
Granulomatous mastitis, also called granulomatous lobular mastitis, is a benign pathology of the mammary gland characterized by chronic inflammation of the gland tissue, which becomes erythematous, manifesting itself ...Granulomatous mastitis, also called granulomatous lobular mastitis, is a benign pathology of the mammary gland characterized by chronic inflammation of the gland tissue, which becomes erythematous, manifesting itself as a palpable and painful mass on physical examination, sometimes it can be accompanied by abscesses. The following case is a 45-year-old Guatemalan female, with a history of increased volume in the left breast, compromising the upper quadrants. A mammogram was performed, followed by breast ultrasound;the diagnosis was confirmed by histology. The treatment offered was surgery with image controls every six months.展开更多
文摘The singlet-triplet splitting energy gap ΔEs-T= Es - ET is calculated for the ortho-, meta-, and para-xylylenes and their heteroatomic analogous by means of AM1-CI approach. It is shownthat when the radical centers R(R=H2C- ,H2N+- or HN’- ) are twisted sufficiently far out ofconjugation with the benzene ring, ΔEs-T tends to zero or is negative, i.e. ortho-, meta-, and para-phenylenes turn into weak ferromagnetic or antiferromagnetic coupling unit, while they are strong ferromagnetic (meta-isomers) or antiferromagnetic (ortho-, para-isomers) coupling units under planar conformation. It is suggested that serious twisted conformation is not recommended candidate for the design of novel high-spin molecules with stable high-spin ground states by ortho-or para-phenylene coupling unit.
文摘Dinuclear copper complex with biradicals [Cu(hfac)2]2PhBNM(PhBNM = 2,5-bimethyl-1,4-bis(4,4,5,5-tetramethyllimidazoline-1-oxyl-3-oxide)phenyl,hfac=hexafluoroacetylacetonate) has been synthesized and characterized. It crystallized in the monoclinic system, with space group C2/c, a=1.9012(4), b=1.3718(3), c=2.1620(4) nm, β=97.55(3)°, Z=4. The X-ray structure analysis shows that the molecular structure consists of two kinds of conformations. The ratio of them is 7:3. The energy of two conformations, calculated with molecular mechanics, are different, E1=740 kJ/mol, and E2=771 kJ · mol-1. The CNDO/k results on the complex indicate that the orbital energy of low spin state is lower than that of high spin state, which correspond with the results of magnetic measurement.
基金This work was supported by the National Natural Science Foundation of China(grant nos.92061202,22175181,and 21531008)the Fujian Science and Technology Project(grant no.2020L3022)the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDB20000000).
文摘Photochromism due to organometallic ring-closure through C−C linkage has never been attained.In this work,we report a preliminary approach to achieve T-type photochromism by creating a metallacyclopentadiene biradical under light irradiation.A class of CuPt2 phenylacetylide compounds was prepared with distinguished photochromic recyclability and durability,which involved the formation of thermally sensitive copper(I)-butadienyl,five-membered ring through copper(I)-participated ring-closure.Upon UV light irradiation,the metallacyclopentadiene with copper(I)center chelated by 1,3-butadiene-1,4-diyl biradical was generated through photochemical C-C linkage of two face-to-face oriented ethynyl units in close proximity,giving rise to a drastic change in UV-vis absorption spectrum.When UV light irradiation was ceased,decoloration occurred through thermal cycloreversion,which endowed the photochromic CuPt2 complexes with self-recovery characteristics.Electron paramagnetic resonance(EPR)spectral study confirmed a biradical feature of a ring-closed isomer.The thermal decoloration half-lives at ambient temperature were regulated from seconds to hours by increasing F substituents in phenylethynyl ligands.
基金Project supported by the National Natural Science Foundation of China (Nos. 29871019 and 29631040) and the Natural Science Foundation of Yunnan Province (No. 1999B0003M).
文摘Five novel complexes of formula [Ln(hfac)3] · BNPhOM, where La = Gd, Ho, Dy, Y, Er; Mac = hexfluoracetylacetonate; BNPhOM=1,3-[bis-2,2′,-(4,4,5,5-tetramethyl-4,5-di-hydro-1H-imidazolyl-1-oxyl-3-oxide) phenoxy] propane, have been prepared and characterized by elemental analysis, molar conductances, IR and electronic spectra. The temperature dependence of the magnetic susceptibility for Gd(III) and radical was measured (2—-300 K). The observed data were successfully simulated giving the exchange integral J = 0.28 cm?1, J' = - 0.33 cm?1. These results indicate a weak ferromagnetic spin exchange interaction between Gd(III) ion and the radical and a weak antiferromagnetic spin exchange interaction between the radical and radical.
基金Supported by the National Natural Science Foundation of Chana(Nos. 29804002, 20274006) and Tianjin Polytechnic Univer-sity Item(Nos. 029307, 029302).
文摘Novel stable high-spin molecules possessing three different arranging fashions were designed with —^＊N—S— as a spin-containing （SC） fragment, an aromatic group, such as benzene （ 1 ）, pyridine （2）, pyridazine （3） , pyrimidine （4）, pyrazine （5） or triazine （6） as end groups （EG）, and phenyl as a ferromagnetic coupling （FC） unit. The effects of different EG on the spin multiplicities of the ground states and their stabilities were investigated by means of the AM1-CI approach. All the investigated molecules corresponded to the FC and possessed high-spin ground states. The spin on the two atoms of the SC fragment was not in agreement with the delocalization results in the specific stability of —^＊N—S—. In those molecules, the stabilities of the triplet states decreased when the distance between the atoms of central SC fragments （—N—） increased. The stabilities of the triplet states of compounds 1a-n, 1b-n and 1c-n, with heterocycles as EG were higher than those of the triplet states of those compounds with phenyl as EG. Furthermore, the stahilities of the triplet states of the compounds with pyrimidine and triazine as EG were higher than those with pyridine, pyridazine or pyrasine as EG.
基金Supported by the National Natural Science Foundation of China( No.2 980 4 0 0 2,2 0 2 74 0 0 6 ) ,FokYingTungEducationFoundation( No.710 13) and Foundation of Northeast Normal University( No.1114 34)
文摘Novel stable high spin molecules possessing three different arranged fashions are designed with - · N-N< as a spin-containing(SC) fragment, phenylene as an end group and various aromatic molecules, such as benzene(1), 2,6-pyridine(2), 3,5-pyridine(3), pyridazine(4), 4,6-pyrimidine(5), 2,6-pyrimidine(6), pyrazine(7) and triazine(8), as a ferromagnetic coupling(FC) unit. The effects of the different coupling units on the spin multiplicities of the ground states and their stabilities were investigated by means of AM1-CI approach. It has been found that the spin densities on the two atoms of the SC fragment are different from delocalization results in the specific stability of - · N-N<. In these molecules, the stabilities of the triplet states decrease when the distance between the atoms of central SC(-N-) increases. It is shown that the heterocycles as the coupling units have influence on the stabilities of the high-spin ground states. That the heteroatom lying in m -phenyl can improve ferromagnetic coupling, while the heteroatom lying in o -phenyl or p -phenyl is not in favor of the ferromagnetic coupling.
文摘The series of biradicals with m phenylene coupling unit and hetero spin centers were calculated compared with those possessing homo spin centers using AM1 CI method. A simple rule was proposed to design high spin molecules with ferromagnetic coupling unit and hetero spin centers. Two neutral (or charged) hetero spin centers resulted in high spin ground state, one neutral and another charged hetero spin centers correspond to low spin ground state. The latter was ascribed to the huge splitting of two partially occupied molecular orbitals.
基金Authors would like to acknowledge the support of the Deputy for Research and Innovation-Ministry of Education,Kingdom of Saudi Arabia for this research through a project grant(NU/IFC/ENT/01/009)under the institutional Funding Committee at Najran University,Kingdom of Saudi Arabia.
文摘Breast cancer(BC)is the most common cause of women’s deaths worldwide.The mammography technique is the most important modality for the detection of BC.To detect abnormalities in mammographic images,the Breast Imaging Reporting and Data System(BI-RADs)is used as a baseline.The correct allocation of BI-RADs categories for mammographic images is always an interesting task,even for specialists.In this work,to detect and classify the mammogram images in BI-RADs,a novel hybrid model is presented using a convolutional neural network(CNN)with the integration of a support vector machine(SVM).The dataset used in this research was collected from different hospitals in the Qassim health cluster of Saudi Arabia.The collection of all categories of BI-RADs is one of the major contributions of this paper.Another significant contribution is the development of a hybrid approach through the integration of CNN and SVM.The proposed hybrid approach uses three CNN models to obtain ensemble CNN model results.This ensemble model saves the values to integrate them with SVM.The proposed system achieved a classification accuracy,sensitivity,specificity,precision,and F1-score of 93.6%,94.8%,96.9%,96.6%,and 95.7%,respectively.The proposed model achieved better performance compared to previously available methods.
文摘Granulomatous mastitis, also called granulomatous lobular mastitis, is a benign pathology of the mammary gland characterized by chronic inflammation of the gland tissue, which becomes erythematous, manifesting itself as a palpable and painful mass on physical examination, sometimes it can be accompanied by abscesses. The following case is a 45-year-old Guatemalan female, with a history of increased volume in the left breast, compromising the upper quadrants. A mammogram was performed, followed by breast ultrasound;the diagnosis was confirmed by histology. The treatment offered was surgery with image controls every six months.
