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1.
Compr Psychiatry ; 133: 152487, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38714144

ABSTRACT

BACKGROUND: The incidence of non-suicidal self-injury (NSSI) has been on the rise in recent years. Studies have shown that people with NSSI have difficulties in emotion regulation and cognitive control. In addition, some studies have investigated the cognitive emotion regulation of people with NSSI which found that they have difficulties in cognitive emotion regulation, but there was a lack of research on cognitive emotion regulation strategies and related neural mechanisms. METHODS: This study included 117 people with NSSI (age = 19.47 ± 5.13, male = 17) and 84 non-NSSI participants (age = 19.86 ± 4.14, male = 16). People with NSSI met the DSM-5 diagnostic criteria, and non-NSSI participants had no mental or physical disorders. The study collected all participants' data of Cognitive Emotion Regulation Questionnaire (CERQ) and functional magnetic resonance imaging (fMRI) to explore the differences in psychological performance and brain between two groups. Afterwards, Machine learning was used to select the found differential brain regions to obtain the highest correlation regions with NSSI. Then, Allen's Human Brain Atlas database was used to compare with the information on the abnormal brain regions of people with NSSI to find the genetic information related to NSSI. In addition, gene enrichment analysis was carried out to find the related pathways and specific cells that may have differences. RESULTS: The differences between NSSI participants and non-NSSI participants were as follows: positive refocusing (t = -4.74, p < 0.01); refocusing on plans (t = -4.11, p < 0.01); positive reappraisal (t = -9.22, p < 0.01); self-blame (t = 6.30, p < 0.01); rumination (t = 3.64, p < 0.01); catastrophizing (t = 9.10, p < 0.01), and blaming others (t = 2.52, p < 0.01), the precentral gyrus (t = 6.04, pFDR < 0.05) and the rolandic operculum (t = -4.57, pFDR < 0.05). Rolandic operculum activity was negatively correlated with blaming others (r = -0.20, p < 0.05). Epigenetic results showed that excitatory neurons (p < 0.01) and inhibitory neurons (p < 0.01) were significant differences in two pathways, "trans-synaptic signaling" (p < -log108) and "modulation of chemical synaptic transmission" (p < -log108) in both cells. CONCLUSIONS: People with NSSI are more inclined to adopt non-adaptive cognitive emotion regulation strategies. Rolandic operculum is also abnormally active. Abnormal changes in the rolandic operculum of them are associated with non-adaptive cognitive emotion regulation strategies. Changes in the excitatory and inhibitory neurons provide hints to explore the abnormalities of the neurological mechanisms at the cellular level of them. Trial registration number NCT04094623.

2.
Sci Rep ; 14(1): 12081, 2024 May 27.
Article in English | MEDLINE | ID: mdl-38802526

ABSTRACT

Early assessment and accurate staging of liver fibrosis may be of great help for clinical diagnosis and treatment in patients with chronic hepatitis B (CHB). We aimed to identify serum markers and construct a machine learning (ML) model to reliably predict the stage of fibrosis in CHB patients. The clinical data of 618 CHB patients between February 2017 and September 2021 from Zhejiang Provincial People's Hospital were retrospectively analyzed, and these data as a training cohort to build the model. Six ML models were constructed based on logistic regression, support vector machine, Bayes, K-nearest neighbor, decision tree (DT) and random forest by using the maximum relevance minimum redundancy (mRMR) and gradient boosting decision tree (GBDT) dimensionality reduction selected features on the training cohort. Then, the resampling method was used to select the optimal ML model. In addition, a total of 571 patients from another hospital were used as an external validation cohort to verify the performance of the model. The DT model constructed based on five serological biomarkers included HBV-DNA, platelet, thrombin time, international normalized ratio and albumin, with the area under curve (AUC) values of the DT model for assessment of liver fibrosis stages (F0-1, F2, F3 and F4) in the training cohort were 0.898, 0.891, 0.907 and 0.944, respectively. The AUC values of the DT model for assessment of liver fibrosis stages (F0-1, F2, F3 and F4) in the external validation cohort were 0.906, 0.876, 0.931 and 0.933, respectively. The simulated risk classification based on the cutoff value showed that the classification performance of the DT model in distinguishing hepatic fibrosis stages can be accurately matched with pathological diagnosis results. ML model of five serum markers allows for accurate diagnosis of hepatic fibrosis stages, and beneficial for the clinical monitoring and treatment of CHB patients.


Subject(s)
Biomarkers , Hepatitis B, Chronic , Liver Cirrhosis , Machine Learning , Humans , Liver Cirrhosis/blood , Liver Cirrhosis/diagnosis , Liver Cirrhosis/pathology , Hepatitis B, Chronic/blood , Hepatitis B, Chronic/complications , Hepatitis B, Chronic/pathology , Biomarkers/blood , Female , Male , Adult , Middle Aged , Retrospective Studies
3.
Medicine (Baltimore) ; 103(11): e37608, 2024 Mar 15.
Article in English | MEDLINE | ID: mdl-38489674

ABSTRACT

BACKGROUND: Idiopathic mesenteric phlebosclerosis (IMP) is a rare gastrointestinal disease with unclear etiology and pathogenesis. IMP occurring in a patient with liver cirrhosis is more scarcely reported than independent IMP. In this study, we reported a case of IMP occurring in a patient with liver cirrhosis, so as to provide a reference for understanding liver cirrhosis with IMP. METHOD: A 63-year-old man with liver cirrhosis was admitted in the hospital's department of infectious disease because of fatigue and constipation for 1 month. The patient had an irregular medical history of antivirus drug and Chinese herbal medicine intake because of the hepatitis B virus infection. No other abnormalities were found in the functions of the liver, coagulation, renal, or complete blood count. Fecal occult blood tests were all positive in 5 detections. Contrast-enhanced computed tomography revealed liver cirrhosis and showed thickening of the wall of the right hemicolon and multiple calcifications of the mesenteric veins. Mesenteric vein computed tomography venography displayed diffuse colon mural thickening of the right colon and tortuous linear calcification line in the right colic veins. Colonoscopy revealed a purple-blue, swollen, rough, and vanished vascular texture mucosa. He was finically diagnosed as liver cirrhosis with IMP by a series of examinations during hospitalization. RESULTS: His symptoms of fatigue and constipation subsided after conservative treatment and withdraw from Chinese herbal medicine. The patient experienced no obvious discomfort during the follow-up period. CONCLUSION: A comprehensive medical diagnosis is necessary for the discovery of IMP, especially IMP with liver cirrhosis. Liver cirrhosis maybe play a key role in the development of IMP. The regulatory mechanism of liver cirrhosis contributing to IMP needs to be further studied based on more clinical cases.


Subject(s)
Calcinosis , Drugs, Chinese Herbal , Male , Humans , Middle Aged , Drugs, Chinese Herbal/adverse effects , Colon/pathology , Colonoscopy , Calcinosis/pathology , Liver Cirrhosis/complications , Liver Cirrhosis/pathology , Constipation
4.
Anal Chem ; 94(50): 17485-17493, 2022 12 20.
Article in English | MEDLINE | ID: mdl-36480597

ABSTRACT

Hypochlorous acid (HOCl) and peroxynitrite (ONOO-) are two important highly reactive oxygen/nitrogen species, which commonly coexist in biosystems and play pivotal roles in many physiological and pathological processes. To investigate their function and correlations, it is urgently needed to construct chemical tools that can track the production of HOCl and ONOO- in biological systems with distinct fluorescence signals. Here, we found that the coumarin fluorescence of coumarin-benzopyrylium (CB) hydrazides (spirocyclic form) is dim, and their fluorescence properties are controlled by their benzopyran moiety via an intramolecular photo-induced electron transfer (PET) process. Based on this mechanism, we report the development of a fluorescent probe CB2-H for the simultaneous detection of HOCl and ONOO-. ONOO- can selectively oxidize the hydrazide group of CB2-H to afford the parent dye CB2 (Absmax/Emmax = 631/669 nm). In the case of HOCl, it undergoes an electrophilic attack on the benzopyran moiety of CB2-H to give a chlorinated product CB2-H-Cl, which inhibits the PET process within the probe and thus affords a turn-on fluorescence response at the coumarin channel (Absmax/Emmax = 407/468 nm). Due to the marked differences in absorption/emission wavelengths between the HOCl and ONOO- products, CB2-H enables the concurrent detection of HOCl and ONOO- at two independent channels without spectral cross-interference. CB2-H has been applied for dual-channel fluorescence imaging of endogenously produced HOCl and ONOO- in living cells and zebrafish under different stimulants. The present probe provides a useful tool for further exploring the distribution and correlation of HOCl and ONOO- in more biosystems.


Subject(s)
Fluorescent Dyes , Peroxynitrous Acid , Animals , Fluorescent Dyes/chemistry , Peroxynitrous Acid/chemistry , Hypochlorous Acid/chemistry , Zebrafish , Reactive Nitrogen Species , Optical Imaging , Coumarins/chemistry
5.
J Phys Chem A ; 125(3): 843-847, 2021 Jan 28.
Article in English | MEDLINE | ID: mdl-33444026

ABSTRACT

A family of novel compounds with planar tetracoordinate silicon (ptSi) supported by B-heterocyclic carbenes (BHCs) have been theoretically investigated. The lowest energy molecules (a3, b3, and c3) with single ptSi are a triplet. We further designed 1D and 2D compounds with multi-ptSi atoms by condensation of a3 along latitudinal (m) and longitudinal (n) directions. The lowest energy 1D compounds prefer to be zigzag conformation along the m direction. The lowest energy 2D compounds (m,n) (m ≥ n) are zigzag conformation along both m and n directions. The total spin quantum number (S) of the lowest energy compounds with ptSi is equal to the number of ptSi. Thus, the compounds with ptSi stabilized by BHCs are magnetic. The singly occupied molecular orbitals (SOMOs) of such compounds are mainly the linear combination of the 3p orbitals of ptSi, indicating that the magnetism of the compounds originates from ptSi.

6.
Anal Chem ; 91(16): 10894-10900, 2019 08 20.
Article in English | MEDLINE | ID: mdl-31331163

ABSTRACT

Acrylate has been widely used as the recognition unit for Cys fluorescent probes. Despite this widespread use, a potential drawback of this probe type is that the ester linkage between the fluorophore and acryloyl recognition unit is liable to be hydrolyzed by abundant esterase in the cytosol, thus affording a high background signal. To solve this problem, we herein put forward a new strategy to construct a selective fluorescent probe for cysteine (Cys)/homocysteine (Hcy) with propynamide as the recognition moiety. The free probe CPA displays weakly fluorescent emission in aqueous media because of the donor-excited photoinduced electron transfer (d-PET) process within the molecule. The Michael addition of Cys (or Hcy) thiols to the conjugated alkyne of CPA gives the expected ß-sulfido-α,ß-unsaturated amides (1a/1b), which subsequently undergo an intramolecular S,N rearrangement, yielding ß-amino-α,ß-unsaturated amides (2a/2b) as the final products. The above cascade reaction results in the blockage of d-PET within CPA, thus affording a dramatic fluorescence enhancement at 495 nm. The involvement of the sulfhydryl and the adjacent amino groups in the sensing process renders CPA high selectivity for Cys/Hcy over glutathione as well as other amino acids. The probe has been successfully applied to image Cys in different cell lines. Further, CPA shows two-photon fluorescence properties, and its ability to monitor Cys in deep tissues has been demonstrated by using two-photon microscopy.


Subject(s)
Amides/chemistry , Cysteine/analysis , Fluorescence , Homocysteine/analysis , Sulfhydryl Compounds/chemistry , Acrylates/chemistry , Electron Transport , Fluorescent Dyes/chemistry , Photochemical Processes
7.
Exp Gerontol ; 112: 20-29, 2018 10 02.
Article in English | MEDLINE | ID: mdl-30120932

ABSTRACT

Growing evidence shows that enhanced reactive oxygen species (ROS) production is an important contributor to obesity and its co-morbidities, but the functional link between ROS and obesity remains elusive. In this study we used the model animal Caenorhabditis elegans to explore the role of ROS in obesity. Initially, when ROS production was enhanced by treatment with low concentration of paraquat or juglone, both abnormal high fat accumulation and fatty acid composition were observed in wild type worms. We found that the abnormal fat accumulation was associated with increased expression of fat-5, which encodes an isoform of stearoyl-CoA synthetase, and which is regulated by daf-16 encoding the forkhead transcription factor and being activated by downregulation daf-2. When mutant daf-16 worms were used, the abnormal fat accumulation induced by ROS was suppressed. Collectively, we demonstrate that enhanced ROS production can lead to excessive fat accumulation and the change of fatty acid composition. This abnormal phenomenon at least in part depends on the daf-16 pathway by which fat-5 was regulated. The results point towards a role of ROS in obesity in the context of important conserved signaling pathway, thereby guide further studies and future therapeutic interventions.


Subject(s)
Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans/genetics , Fatty Acids/metabolism , Forkhead Transcription Factors/genetics , Longevity/genetics , Reactive Oxygen Species/metabolism , Animals , Caenorhabditis elegans/growth & development , Mutation , Oxidative Stress , RNA Interference , Receptor, Insulin/genetics , Signal Transduction
8.
Inorg Chem ; 57(13): 8019-8027, 2018 Jul 02.
Article in English | MEDLINE | ID: mdl-29927594

ABSTRACT

It is rather challenging to develop photocatalysts based on narrow-band-gap semiconductors for water splitting under solar irradiation. Herein, we synthesized the Cu2O/Cu2Se multilayer heterostructure nanowires exposing {111} crystal facets by a hydrothermal reaction of Se with Cu and KBH4 in ethanol amine aqueous solution and subsequent annealing in air. The photocatalytic H2 production activity of Cu2O/Cu2Se multilayer heterostructure nanowires is dramatically improved, with an increase on the texture coefficient of Cu2O(111) and Cu2Se(111) planes, and thus the exposed {111} facets may be the active surfaces for photocatalytic H2 production. On the basis of the polar structure of Cu2O {111} and Cu2Se {111} surfaces, we presented a model of charge separation between the Cu-Cu2Se(111) and O-Cu2O(1̅ 1̅ 1̅) polar surfaces. An internal electric field is created between Cu-Cu2Se(111) and O-Cu2O(1̅ 1̅ 1̅) polar surfaces, because of spontaneous polarization. As a result, this internal electric field drives the photocreated charge separation. The oxidation and reduction reactions selectively occur at the negative O-Cu2O(1̅ 1̅ 1̅) and the positive Cu-Cu2Se(111) surfaces. The polar surface-engineering may be a general strategy for enhancing the photocatalytic H2-production activity of semiconductor photocatalysts. The charge separation mechanism not only can deepen the understanding of photocatalytic H2 production mechanism but also provides a novel insight into the design of advanced photocatalysts, other photoelectric devices, and solar cells.

9.
Chemistry ; 24(40): 10216-10223, 2018 Jul 17.
Article in English | MEDLINE | ID: mdl-29714815

ABSTRACT

1-Borabicyclo[1.1.0]but-2(3)-ene (1BB) is a singlet biradical with two single electrons that can form an ionic resonance structure through a charge shift. The ionic resonance structure is a B-heterocyclic carbene (BHC), which can act as a carbene, Lewis base, or L- and Z-type ligand, to give adducts and complexes. Through a range of quantum methods, four types of stable compounds (A-D) derived from 1BB have been designed. These compounds retain the unique features of 1BB. As a consequence, the structures, stability, and Wiberg bond indices of the Lewis adducts of A-D with Lewis acids (BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , and C13 BH9 ) and CuI , AgI , and AuI complexes have been investigated. Results show that A-D can indeed react as carbenes. Interestingly, compounds A-D, as L-type ligands, can attach to BePh2 , BH3 , AlH3 , AlCl3 , C5 BH5 , C13 BH9 , and CuCl and form compounds with planar tetracoordinate carbon (ptC), whereas Z-type ligands A-D can bind to AgCl and AuCl to provide complexes with planar tetracoordinate boron (ptB). In addition, the binuclear complexes of ClX(1BB)CuCl (X=Ag, Au) have been studied and A-D behave as both L- and Z-type ligands, in which these complexes contain both ptC and ptB. Thus, a novel method for designing compounds with ptC and ptB is presented. These rationally designed compounds involve the elements of carbene, ptC, ptB, and L- and Z-type ligands, and are expected to be unique and useful in experimental chemistry once they are synthesized.

10.
Phys Chem Chem Phys ; 19(3): 2417-2424, 2017 Jan 18.
Article in English | MEDLINE | ID: mdl-28058426

ABSTRACT

In this work, five new palladium(ii) complexes have been designed as the model catalysts for methane to methyl trifluoroacetate conversion. All these compounds are analogues of the well-established (bis-NHC)PdBr2 complex (NHC, N-heterocyclic carbenes), derived by complexing the palladium(ii) metal ion with the derivatives of bis-2-borabicyclo[1.1.0]but-1(3)-ene (bis-2BB) ligands using the sp2 carbons. Our density functional theory calculation results suggest that the (bis-2BB)PdBr2 catalysts outperform the popular (bis-NHC)PdBr2 complex in the desired catalytic process, and further reveal that the charge-shift bonding in the bis-2BB ligands contributes to the improved catalytic performance. These findings may spark new ideas for experimental design of more efficient organometallic catalysts for C-H bond activation and functionalization.

11.
ACS Omega ; 1(4): 620-625, 2016 Oct 31.
Article in English | MEDLINE | ID: mdl-31457151

ABSTRACT

We have theoretically investigated the stability, chemical bonding, and coordination ability of the 2-Me-2-borabicyclo[1.1.0]but-1(3)-ene (2-Me-2BB) molecule using density functional theory and ab initio molecular dynamics (AIMD) simulations. Calculated results indicated that 2-Me-2BB is both thermodynamically and kinetically stable. The C=C bonds in 2-Me-2BB contain a π bond and a charge shift (CS) bond, different from those in 1-Me-borirene and cyclopropylene. Moreover, 2-Me-2BB can be a σ donor, leading to the formation of TM(2-Me-2BB)L n complexes containing planar tetracoordinate carbon (ptC) with transition metals (TM = Sc-Cu), in which the lone electron pair of 2-Me-2BB results from its ionic resonance form. The lengths and Wiberg bond indices of the TM-ptC bond in TM(2-Me-2BB)L n (TM = Sc-Cu) reveal that 2-Me-2BB can be a ligand similar to N-heterocyclic carbene. Therefore, 2-Me-2BB and its derivatives are promising molecules to obtain complexes with ptC. The natural charges on TM atoms in TM(2-Me-2BB)L n (TM = Sc-Cu) complexes range from -0.97 to 1.54e, indicating that such complexes with ptC might have potential applications in catalytic chemistry.

12.
J Phys Chem A ; 119(33): 8950-7, 2015 Aug 20.
Article in English | MEDLINE | ID: mdl-26218898

ABSTRACT

Ten derivatives of 2-borabicyclo[1.1.0]but-1(3)-ene (1a-1j) with different degrees of frustration have been investigated using density functional theory. Moreover, 1a-1j as Lewis bases were used to form Lewis adducts C3X2BYH/B(C6F5)3 (2a-2j) with Lewis acid B(C6F5)3. Optimized geometries and the thermodynamic properties of giving the Lewis adducts C3X2BYH/B(C6F5)3 reveal that 2a-2j are frustrated Lewis pairs (FLPs). Their reactivity of activating H2 and HF show that 2a-2j are unfavorable to heterolytically cleave H2, whereas 2c-2j can cleave HF to form [C3X2BYH](+)[FB(C6F5)3](-). In addition, we found the structures of [C3X2BYH](+) in [C3X2BYH](+)[FB(C6F5)3](-) contained a planar tetracoordinate carbon (ptC). Therefore, a new method of obtaining main group element compounds with ptC by using FLPs was presented.

13.
Phys Chem Chem Phys ; 17(20): 13280-9, 2015 May 28.
Article in English | MEDLINE | ID: mdl-25920433

ABSTRACT

The search for active narrow band gap semiconductor photocatalysts that directly split water or degrade organic pollutants under solar irradiation remains an open issue. We synthesized Cu2Se nanowires with exposed {111} facets using ethanol and glycerol as morphology controlling agents. The {111} facets were found to be the active facets for decomposing organic contaminants in the entire solar spectrum. Based on the polar structure of the Cu2Se {111} facets, a charge separation model between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces is proposed. The internal electric field between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces created by spontaneous polarization drives charge separation. The reduction and oxidation reactions occur on the positive (111) and negative (1[combining macron]1[combining macron]1[combining macron]) polar surfaces, respectively. This suggests the surface-engineering of narrow band gap semiconductors as a strategy to fabricate photocatalysts with high reactivity in the entire solar spectrum. The charge separation model can deepen the understanding of charge transfer in other semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts as well as new types of solar cells, photoelectrodes and photoelectric devices.

14.
ACS Appl Mater Interfaces ; 7(11): 6109-17, 2015 Mar 25.
Article in English | MEDLINE | ID: mdl-25734621

ABSTRACT

Crystal facet engineering of semiconductors has been proven to be an effective strategy to increase photocatalytic performances. However, the mechanism involved in the photocatalysis is not yet known. Herein, we report our success in that photocatalytic performances of the Cl(-) ion capped CoO octahedrons with exposed {111} facets were activated by a treatment using AgNO3 and NH3·H2O solutions. The clean CoO {111} facets were found to be highly reactivity faces. On the basis of the polar structure of the exposed {111} surfaces, a charge separation model between polar {111} surfaces is proposed. There is an internal electric field between polar {111} surfaces due to the spontaneous polarization. The internal electric field provides a driving force for charge separation. The reduction and oxidation reactions selectively take place on the positive and negative polar {111} surfaces. The charge separation model provides a clear insight into charge transfer in the semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts, solar cells, photoelectrodes, and other photoelectronic devices.

15.
J Phys Chem A ; 116(36): 9123-30, 2012 Sep 13.
Article in English | MEDLINE | ID: mdl-22913722

ABSTRACT

We have designed a family of novel molecules that can act as a donor at a carbon atom to coordinate with Ag(I) and Au(I) to achieve stable complexes with a planar tetracoordinate carbon (ptC). Then, a kind of new strategy for the design of the compound with a ptC was provided.

16.
J Phys Chem A ; 114(30): 7960-6, 2010 Aug 05.
Article in English | MEDLINE | ID: mdl-20617799

ABSTRACT

We have investigated the structures, stabilities, aromaticities, and Wiberg bond indices of four types of compounds (8-like, trapezia, umbrella-like, and quadrangle) containing planar tetracoordinate carbon (ptC), and the stability rules for the compound with ptC were concluded on the basis of extensive calculations. Generally, the stability or viability of compound with ptC strongly depends on the number of three-membered ring and conjugated three-membered ring, as well as pi electrons. These rules can be successfully used to identify the stability of other compounds reported in previous studies. On the basis of these rules, eight stable compounds with planar tetracoordinate nitrogen (ptN) are successfully constructed.

17.
Chem Commun (Camb) ; (31): 4714-6, 2009 Aug 21.
Article in English | MEDLINE | ID: mdl-19641819

ABSTRACT

A new route for constructing PAHs from cyclohexanone by trimerization, bromination, trisannulation and aromatization, and the synthesis of a novel sulfur-containing polycyclic heteroaromatic have been described.

18.
J Mol Model ; 15(2): 157-63, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19043749

ABSTRACT

The structures and electronic properties of the triatomic molecules containing Al, P, X atoms (X = B, Al, Ga; C, Si, Ge; N, P, As; O, S and Se) and their anions are investigated at the B3LYP/cc-PVTZ and the B3LYP/aug-cc-PVTZ levels. The results show that the most stable structures of the anions are AlXP(-) (X = B, C, N) and PAlX(-) (X = S, Se), while for the neutral molecules, the most stable structures are PXAl (X = C, N and O). The order of the VDEs of the anions molecules and the AEAs of the neutral species are C < N < O < Si approximately Ge < P approximately As < Al = Ga < B < S approximately Se and C < O < N < Si approximately Ge < P approximately As < B < Al approximately Ga < S approximately Se, respectively.


Subject(s)
Aluminum Compounds/chemistry , Aluminum/chemistry , Models, Chemical , Phosphines/chemistry , Phosphorus/chemistry , Arsenic/chemistry , Boron/chemistry , Carbon/chemistry , Computer Simulation , Electrons , Gallium/chemistry , Germanium/chemistry , Molecular Structure , Nitrogen/chemistry , Oxygen/chemistry , Selenium/chemistry , Silicon/chemistry , Sulfur/chemistry
19.
J Am Chem Soc ; 130(17): 5638-9, 2008 Apr 30.
Article in English | MEDLINE | ID: mdl-18393494

ABSTRACT

Four kinds of novel zigzag boron-carbon nanotubes with quasi-planar tetracoordinate carbons (2m, 0, i) (m = 3-6; i = 1-4) have been constructed, and their structures, stabilities, and bonding properties have been investigated by B3LYP calculations. The results show that the novel nanotubes (m, 0, i) have the character of metal properties with quite small HOM-LUMO gaps. Structurally, there are big windows on the walls of nanotubes and they are promising in design for functional materials.

20.
J Phys Chem A ; 111(38): 9471-8, 2007 Sep 27.
Article in English | MEDLINE | ID: mdl-17696326

ABSTRACT

Different forms of pi-conjugated polyarylmethyl systems, such as diradicals, polyradicals, spin clusters, and polymers, were studied with valence bond (VB) calculations within the density matrix renormalization group (DMRG) framework. For these systems, the energy gap between the high-spin ground state and the lowest low-spin excited state (DeltaE(L-H)) was computed and found to correlate well with their stability. On the basis of our analysis, medium-sized polyarylmethyl cycles are suggested to be potential key building blocks of very high spin spin clusters and polymers.

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