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1.
Dalton Trans ; 52(19): 6398-6406, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37092261

RESUMO

The aerobic oxidation of ethylbenzene is an effective way to produce acetophenone, in which solvent-free conditions and oxygen as the sole oxidant are the best choice. At present, the catalytic activity and selectivity are still at an unsatisfactory level, because efficient catalysts need to achieve both C-H bond activation and O2 activation. In this work, the 2-methylimidazole-induced hydrolysis strategy was used to prepare a new class of CoNi-layered double hydroxide (CoNi-LDH) materials with different metal ratios. High-Resolution Transmission Electron Microscopy (HRTEM) showed that CoNi-LDH had obvious weak crystallinity and a thin lamellar structure. X-ray Photoelectron Spectroscopy (XPS) reveals the consistency between the content of the M-O component in the host layer and the proportion of Co3+, among which CoNi-LDH with a feed ratio (Co : Ni) of 2 : 1 (Co2Ni-LDH) has the highest M-O content and Co3+ ratio. The formation of M-O is due to the H-vacancy generated by the breaking of the hydroxyl group, which can be used for the H abstraction of C-H bonds. The redox effect caused by M2+/M3+ facilitates the transfer of electrons, which promotes the activation of O2 to the superoxide radical anion (˙O2-). Thereby, Co2Ni-LDH shows the highest catalytic activity for the oxidation of ethylbenzene. Under solvent-free conditions and with oxygen as the sole oxidant, 97.8% conversion of ethylbenzene and 98.8% selectivity of acetophenone can be obtained. The excellent catalytic performance is related to the structure of CoNi-LDH, and is also the best when compared with the reported results. Various types of aromatic hydrocarbons containing benzyl C-H bonds can be effectively oxidized by CoNi-LDH to produce the corresponding ketone products.

2.
Curr Microbiol ; 79(1): 1, 2021 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-34878563

RESUMO

Despites Providencia heimbachae has been isolated from human, penguin, and bovine fetus, relatively little information is available regarding the pathogenicity and biologic characteristics of P. heimbachae. Here, we report that investigation of post-weaning diarrhea yielded bacterial isolates identified as P. heimbachae based on the biochemical tests and 16S ribosomal DNA sequence analysis. The two isolates were positive for utilization of Malonate, no gas production from glucose, and non-fermentation of D-mannitol, D-Galactose, and L-Rhamnose that were different from those of the type strain, and both of them have the ability of adhesion and invasion to IPEC-J2 cells, and were resistant to 21 out of the 41 antibiotics tested. In addition, the isolate 99101 was highly pathogenic to mice and piglets. Histopathology studies on nerve tissue of piglets that developed hindlimb paralysis showed microglia cell infiltration and neuron damage in the spinal cord. Notably, the strains could grow under low temperature (4 °C), which raise attention of a new risk factor for food safety. To the best of our knowledge, this is the first report of P. heimbachae strain caused post-weaning diarrhea in piglets in both natural and experimental conditions. These findings extended the knowledge of P. heimbachae as an important zoonotic agent, which should be given more attention during surveillance and diagnostics.


Assuntos
Providencia , Doenças dos Suínos , Animais , Bovinos , Diarreia/veterinária , Camundongos , Fenótipo , Providencia/genética , Suínos , Desmame
3.
Org Biomol Chem ; 18(19): 3740-3746, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32367104

RESUMO

A copper-catalyzed asymmetric 1,3-dipolar cycloaddition of glycine iminoesters with alkyl substituted 3-methylene-2-oxindoles is described. By using de novo design of P-stereogenic phosphines as ligands, spiro[pyrrolidin-3,3'-oxindole]s are generated in good to excellent yields with high asymmetric induction. A further reduced catalyst loading of 0.1 mol% is sufficient to achieve a satisfactory enantioselectivity of 90% ee. The DFT calculations suggest the second Michael addition of the 1,3-dipole to be the rate- and enantio-determining step. A key feature of this 1,3-dipolar cycloaddition is the wide substrate applicability, even with alkyl aldehyde-derived azomethine ylide; thus it has streamlined a highly enantioselective access to a new class of antiproliferative agents, MDM2-p53.

4.
Ultrasound Med Biol ; 45(5): 1221-1233, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30824309

RESUMO

Non-invasive assessment of carotid artery plaque vulnerability is a key issue for cerebrovascular disease. This study investigates Von Mises strain imaging in patients by relating Von Mises strain to cerebral infarction presentation. Ultrasonography was performed in patients evaluated for carotid artery stenosis. Strains were estimated by a flow-driven diffusion method and least-squares regression applying Kalman filtering. Von Mises strains ɛVMsys and ɛVMdia were calculated by averaging four or five cardiac cycles in systole and diastole, respectively. Von Mises strain (peak, coefficient of variance, skewness and kurtosis) in patients with cerebral infarction was compared with that in the control group. Higher Von Mises peak strain localized to echolucent areas on B-mode imaging. Higher peak strain was found in patients with cerebral infarction compared with the control group (p = 0.02 for ɛVMdia and p = 0.001 for ɛVMsys). The area under the receiver operating characteristic curve for peak ɛVMsys was 0.761 (p = 0.001) with high sensitivity and specificity. Peak strain also correlated with homocysteine (r = 0.345, p = 0.007, for ɛVMdia; r = 0.287, p = 0.036, for ɛVMsys) and hypersensitive C-reactive protein (r = 0.399, p = 0.043, for ɛVMdia; r = 0.195, p = 0.034, for ɛVMsys) levels. The coefficient of variance, skewness and kurtosis of ɛVMdia or ɛVMsys were also associated with homocysteine levels. In conclusion, this study indicates that peak Von Mises strain is a potential clinical risk marker for carotid plaque vulnerability and cerebral infarction.


Assuntos
Artérias Carótidas/fisiopatologia , Estenose das Carótidas/diagnóstico por imagem , Infarto Cerebral/diagnóstico , Infarto Cerebral/fisiopatologia , Placa Aterosclerótica/diagnóstico por imagem , Ultrassonografia/métodos , Idoso , Artérias Carótidas/diagnóstico por imagem , Estenose das Carótidas/complicações , Infarto Cerebral/complicações , Feminino , Humanos , Masculino , Placa Aterosclerótica/complicações , Estudos Prospectivos , Fatores de Risco , Sensibilidade e Especificidade
5.
Australas Phys Eng Sci Med ; 41(3): 669-686, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30120756

RESUMO

The elasticity of the vessel wall is important for the clinical identification of rupture-risks. The Von Mises strain can be a potential index for the indication of carotid vessel pathologies. In this paper, a fast clinically applicable real-time algorithm from time-sequence of B-mode carotid images is developed. Due to the compression induced by the normal cardiac pulsation, tissue motion occurs radially and non-rigidly. To obtain an accurate motion field, we developed a variational functional integrating the optical flow equation and an anisotropic regularizer, and designed a diffusion tensor to encourage coherence diffusion. The motion field is smoothed along the desired motion flow orientation. A fast, additive operator splitting scheme, which is ten times faster than the conventional discrete method, is used for the numerical implementation. To demonstrate the efficiency of the proposed approach, finite element models are set up for normal and pathological carotid vessel walls. The results indicate that the proposed diffusion approach obtains an accurate smooth and continuous motion field and greatly improves the follow up strain estimation using a fast differential strain filter. Furthermore, our approach using the Von Mises strain imaging on clinical ultrasound images of the carotid artery is validated. Participants above 65-years in age suffering from different stages of atherosclerosis in their carotid artery are selected. The results are evaluated by an experienced physician. The evaluation results demonstrate that the Von Mises strain has a good correspondence to the presence of certain suspicious areas in the B-mode images. The proposed method is therefore clinically applicable for the real-time Von Mises strain imaging of carotid vessel walls, and can be of great value as a complementary method to B-mode image for the clinical identification of the risk of plaque vulnerability.


Assuntos
Artérias Carótidas/diagnóstico por imagem , Artérias Carótidas/fisiologia , Hemorreologia , Interpretação de Imagem Assistida por Computador , Estresse Mecânico , Ultrassonografia , Espessura Intima-Media Carotídea , Seio Carotídeo/diagnóstico por imagem , Seio Carotídeo/patologia , Difusão , Humanos , Modelos Cardiovasculares , Placa Aterosclerótica/diagnóstico por imagem , Placa Aterosclerótica/patologia
6.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 10): o3058, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23125818

RESUMO

In the title complex, C(8)H(7)N(3)O, the C-O [1.369 (2) and 1.364 (3) Å] and C=N [1.285 (3) and 1.289 (3) Å] bond lengths in the oxadiazole ring are each almost identical within systematic errors, although different substituents are attached to the ring. The phenyl ring is inclined to the planar oxadiazole ring [r.m.s. deviation 0.002 Å] by 13.42 (18)°. In the crystal, molecules are linked via N-H⋯N hydrogen bonds, forming double-stranded chains propagating along [010].

7.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 6): o1668, 2012 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-22719463

RESUMO

In the crystal structure of the title compound, C(9)H(9)N(3)O, adjacent mol-ecules are linked through N-H⋯N hydrogen bonds into a three-dimensional network.

8.
Artigo em Inglês | MEDLINE | ID: mdl-22259374

RESUMO

In the title compound, [Fe(C(5)H(5))(2)(C(13)H(11)N(2)O(2))], the dihedral angle between the benzene ring and the cyclo-penta-diene ring bonded to the carbonyl group is 26.1 (2)°. In the crystal, bifurcated O-H⋯(O,N) and N-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

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