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1.
ISA Trans ; 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-32183992

RESUMO

As a widely-used technology, fluidized bed combustor (FBC) boiler is facing many control challenges such as coupling, high-order dynamics and nonlinearity. With more and more sustainable energy integrating into the bulk power system, the FBC boiler is obliged to speed up the respond to the automatic generation control command and this results in great challenges for keeping the bed temperature in the desired range. To this end, a modified active disturbance rejection control (MADRC) is put forward for high order systems with the type of K∕(Ts+1)n to enhance the control quality of the FBC boiler. Firstly, a simulation is carried out to discuss the estimation ability of the MADRC. A theorem about the stability analysis of the MADRC is provided and proofed theoretically. To help the field personnel to understand and use more easily, an effective tuning procedure is also concluded. Besides, a tuning toolbox based on the tuning procedure is established. Simulations and comparative experiments based on the Peltier temperature control platform validate the superiority of the MADRC, where the MADRC is able to enhance the control quality. Then the MADRC and other comparative controllers (the proportional integral controller and the regular ADRC) are designed for the FBC boiler. Simulation results illustrate that the MADRC can obtain the best performance. Statistical indices show that the MADRC has the smallest overshoot and shortest settling time. In addition, the MADRC still has the strongest ability to reject the input and coal quality variation disturbances. The advantages of the MADRC guarantee the high control quality and can be applied to industrial practice widely.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32153103

RESUMO

Single-atom catalysts have drawn great attention, especially in electrocatalysis. However, most of previous works focus on the enhanced catalytic properties via improving metal loading. Engineering morphologies of catalysts to facilitate mass transport through catalyst layers, thus increasing the utilization of each active site, is regarded as an appealing way for enhanced performance. Herein, we design an overhang-eave structure decorated with isolated single-atom iron sites via a silica-mediated MOF-templated approach for oxygen reduction reaction (ORR) catalysis. This catalyst demonstrates superior ORR performance in both alkaline and acidic electrolytes, comparable to the state-of-the-art Pt/C catalyst and superior to most precious-metal-free catalysts reported to date. This activity originates from its edge-rich structure, having more three-phase boundaries with enhanced mass transport of reactants to accessible single-atom iron sites (increasing the utilization of active sites), which verifies the practicability of such a synthetic approach.

3.
Inorg Chem ; 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32096626

RESUMO

Developing high-efficiency and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is crucial for various energy conversion systems. Herein, N/S co-doped C encapsulated hollow NiCo2O4/NiO hexagonal rods (HNHR@N/S-C) as the electrocatalysts for OER have been successfully prepared with rational control of structure and composition. Experimental and theoretical results have highlighted that the NiCo2O4/NiO heterojunction in the obtained electrocatalyst can provide abundant active Ni and Co sites for the OER, leading to the highly enhanced OER performance. Moreover, attributed to the hierarchical hollow structure, which can provide a large surface area, and the improved electric conductivity with a coating of the N/S co-doped carbon layer, which can facilitate charge transport during the catalytic processes, a remarkable OER activity over HNHR@N/S-C with a low overpotential (η) of 285 mV (at j = 10 mA cm-2) and a Tafel slope of 53.0 mV decade-1 has been achieved, which is comparable to that of the noble metal catalyst IrO2. Because of the protection of the N/S doped C layer coating, HNHR@N/S-C can also maintain the current density of 10 mA cm-2 for at least 12 h in alkaline media without obvious losses of activity.

4.
J Craniofac Surg ; 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-32068725

RESUMO

INTRODUCTION: Using meta-analysis to evaluate the efficacy of absolute ethanol and polidocanol in the treatment of venous malformations. MATERIALS AND METHODS: A systematic search of the English literature was conducted in April 2019 including PubMed, Embase and Web of Science. Article selection was based on preset criteria. The included literature was scored on the MINORS scale, and the meta-analysis and the forest plot were made using the R 3.5.1 software for efficiency. RESULTS: Ten articles were included in the meta-analysis. Absolute ethanol response rate ranged between 79% and 92% with a pooled rate of 85%, and polidocanol response rate ranged between 63% and 94% with a pooled rate of 77%. DISCUSSION: Although sclerotherapy is effective in most studies, a large number of randomized controlled trials are still needed to confirm the best treatment options at different sites.

5.
Inorg Chem ; 59(3): 2104-2110, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31942798

RESUMO

Catalysts based on metallic NPs have shown high activities in heterogeneous catalysis, due to their high fractions of surface-active atoms, which, however, will lead to the sacrifices in stability and recycle of catalysts. In order to balance well the relationship between activity, stability, and recovery, in this paper, we have constructed a 3D mesoporous sphere structure assembled by N-doped carbon coated Ni/Pd NP heterojunctions (Ni/Pd@N-C). This obtained Ni/Pd@N-C has shown high catalytic activity, durability and recyclability for the hydrolytic dehydrogenation of ammonia borane (AB). Further investigations, including experimental and theoretical results, have shown that the unique structural features, the synergistic effect between Ni and Pd, and the coating of N-doped carbon layer are responsible for the good catalytic performance of Ni/Pd@N-C mesoporous spheres.

6.
Chemistry ; 26(4): 921-926, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31693235

RESUMO

Engineering p-n heterojunctions among metal oxide semiconductors to provide a built-in electric field is an efficient strategy to facilitate the separation of photogenerated electrons and holes and improve their photocatalytic activities. However, the inherent poor conductivity of p-n heterojunctions still limits the charge-transfer step and thus hampers their practical application in photocatalysis. In this work, a nitrogen-doped carbon-coated NiO/TiO2 p-n (NCNT) heterojunction with hierarchical mesoporous sphere morphology was synthesized by in situ pyrolytic decomposition of nickel-titanium complexes. The NiO/TiO2 p-n heterojunction in NCNT was fully characterized by several techniques, supported by theoretical calculations and Mott-Schottky plots. On coating with a thin nitrogen-doped carbon layer, the electron transfer of the obtained p-n heterojunction could be significantly enhanced. On account of the favorable structural features of the p-n heterojunction with nitrogen-doped carbon coating and hierarchical mesoporous structure, NCNT exhibited excellent photocatalytic activity toward various reaction systems, including the hydrogen evolution reaction and the visible-light-induced hydroxylation of phenylboronic acids.

7.
Inorg Chem ; 59(1): 937-942, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31858782

RESUMO

N- and S-doped C-encapsulated CeO2 with a hinge-like nanostructure (CeO2@N,S-C HN) has been obtained by using a Ce-based metal-organic framework (Ce-MOF-808) as a precursor. Due to the synergistic effects of its special structure and N,S-doped C layer, CeO2@N,S-C HN exhibits high activity of photocatalytic hydrogen (H2) evolution. Density functional calculations are used to obtain a fundamental understanding of the high H2 production rate of CeO2@N,S-C HN.

8.
Zhongguo Dang Dai Er Ke Za Zhi ; 21(12): 1193-1197, 2019 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-31874658

RESUMO

OBJECTIVE: To investigate the effect of bevacizumab in the treatment of children with optic pathway glioma (OPG). METHODS: A retrospective analysis was performed for the clinical data of 30 children with OPG who underwent chemotherapy. According to whether bevacizumab was used, they were divided into conventional chemotherapy (carboplatin, vincristine and etoposide) group with 12 children and combined chemotherapy (bevacizumab, carboplatin, vincristine and etoposide) group with 18 children. The children were followed up to 6 months after chemotherapy, and the two groups were compared in terms of visual acuity and tumor size before and after chemotherapy and adverse reactions during chemotherapy. RESULTS: The combined chemotherapy group had a significantly higher proportion of children achieving tumor regression than the conventional chemotherapy group (P<0.05), while there were no significant differences between the two groups in the proportion of children with improved visual acuity or adverse reactions (P>0.05). No chemotherapy-related death was observed in either group. CONCLUSIONS: Bevacizumab combined with conventional chemotherapy can effectively reduce tumor size. Compared with conventional chemotherapy, such combination does not increase adverse reactions and can thus become a new direction for the treatment of OPG in children.


Assuntos
Glioma do Nervo Óptico , Protocolos de Quimioterapia Combinada Antineoplásica , Bevacizumab , Carboplatina , Criança , Humanos , Estudos Retrospectivos , Vincristina
9.
Cell Death Differ ; 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31645676

RESUMO

Microtubule-targeting agents (MTAs) are a class of most widely used chemotherapeutics and their mechanism of action has long been assumed to be mitotic arrest of rapidly dividing tumor cells. In contrast to such notion, here we show-in many cancer cell types-MTAs function by triggering membrane TNF (memTNF)-mediated cancer-cell-to-cancer-cell killing, which differs greatly from other non-MTA cell-cycle-arresting agents. The killing is through programmed cell death (PCD), either in way of necroptosis when RIP3 kinase is expressed, or of apoptosis in its absence. Mechanistically, MTAs induce memTNF transcription via the JNK-cJun signaling pathway. With respect to chemotherapy regimens, our results establish that memTNF-mediated killing is significantly augmented by IAP antagonists (Smac mimetics) in a broad spectrum of cancer types, and with their effects most prominently manifested in patient-derived xenograft (PDX) models in which cell-cell contacts are highly reminiscent of human tumors. Therefore, our finding indicates that memTNF can serve as a marker for patient responsiveness, and Smac mimetics will be effective adjuvants for MTA chemotherapeutics. The present study reframes our fundamental biochemical understanding of how MTAs take advantage of the natural tight contact of tumor cells and utilize memTNF-mediated death signaling to induce the entire tumor regression.

10.
Zhongguo Dang Dai Er Ke Za Zhi ; 21(8): 761-765, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31416499

RESUMO

OBJECTIVE: To investigate the risk factors for recurrence of medulloblastoma (MB) within 2 years and their influence on progression-free survival (PFS). METHODS: A retrospective analysis was performed for the clinical data of 123 children with MB who were admitted from January to December, 2017. According to the presence or absence of recurrence, they were divided into recurrence group with 30 children and non-recurrence group with 93 children. The risk factors for recurrence within 2 years were analyzed, and PFS was compared between the children with different risk factors. RESULTS: Large-cell/anaplastic type and M stage were risk factors for MB recurrence within 2 years. The risk of recurrence in the children with M+ MB was 3.525 times that in those with M0 MB, and the risk of recurrence in the children with large-cell/anaplastic MB was 3.358 times that in those with classic MB (P<0.05). The survival analysis showed that the median PFS time was 20 months in the children with M+ MB, and the 20-month PFS rate was 50% ±â€…11% in the children with M+ MB and 81% ±â€…5% in those with M0 MB (P<0.05). The 20-month PFS rate was 80% ±â€…5% in the children with classic MB, 65% ±â€…10% in those with desmoplastic/nodular MB, 86% ±â€…13% in those with MB with extensible nodularity, and 36% ±â€…20% in those with large-cell/anaplastic MB (P<0.05). CONCLUSIONS: Recurrence is an important influencing factor for the prognosis of MB, and M+ stage and large-cell/anaplastic MB are risk factors for recurrence. Children with such risk factors tend to have a low PFS rate.


Assuntos
Neoplasias Cerebelares , Meduloblastoma , Criança , Humanos , Recidiva Local de Neoplasia , Prognóstico , Recidiva , Estudos Retrospectivos , Fatores de Risco
11.
Chemistry ; 25(62): 14133-14139, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31390102

RESUMO

Multicomponent NiTiO3 /A-TiO2 /R-TiO2 photocatalysts coated with nitrogen-doped carbon (N-C/NiTiO3 /A-TiO2 /R-TiO2 ) for efficient H2 production were fabricated by directly pyrolyzing NH2 -MIL-125(Ni/Ti) metal-organic framework microrods. Owing to the synergistic effect of the N-doped carbon coating layer and multicomponent heterojunctions, the H2 production rate of N-C/NiTiO3 /A-TiO2 /R-TiO2 was even higher than that of its Pt-containing counterpart (Pt/NiTiO3 /A-TiO2 /R-TiO2 ). N-C/NiTiO3 /A-TiO2 and N-C/NiTiO3 /R-TiO2 as control photocatalysts were also prepared by simply adjusting the calcination temperature of NH2 -MIL-125(Ni/Ti) in air atmosphere. The H2 production rate followed the order of N-C/NiTiO3 /A-TiO2 /R-TiO2 >N-C/NiTiO3 /A-TiO2 >N-C/NiTiO3 >R-TiO2 , which indicates that the multicomponent heterojunction plays a key role in photocatalytic H2 generation. The mechanism for the influence of the multicomponent heterojunction on photocatalytic activity was investigated in combination with molecular simulations, which showed that N-C/NiTiO3 /A-TiO2 /R-TiO2 has a so-called double type II heterojunction providing a perfect step-by-step migration pathway for effective separation of photogenerated electrons and holes. This work presents a simple and effective method for synthesizing efficient multicomponent photocatalysts.

12.
Microb Cell Fact ; 18(1): 90, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-31122258

RESUMO

BACKGROUND: Surfactin is a cyclic lipopeptide that is of great industrial use owing to its extraordinary surfactant power and antimicrobial, antiviral, and antitumor activities. Surfactin is synthesized by a condensation reaction in microbes, which uses fatty acids and four kinds of amino acids (L-glutamate, L-aspartate, L-leucine and L-valine) as precursors. Surfactin biosynthesis could be improved by increasing the supply of fatty acids; however, the effect of the regulation of amino acid metabolism on surfactin production was not yet clear. RESULTS: In this study, we aimed to improve surfactin production in B. subtilis by repressing the genes on the branch metabolic pathways of amino acid biosynthesis using CRISPRi technology. First, 20 genes were inhibited individually, resulting in 2.5- to 627-fold decreases in transcriptional level as determined by RT-qPCR. Among the 20 recombinant strains, 16 strains obtained higher surfactin titres than that produced by the parent BS168NU-Sd strain (the surfactin production of BS168NU-Sd with only dCas9 but no sgRNA expression was 0.17 g/L). In particular, the strains in which the yrpC, racE or murC genes were inhibited individually produced 0.54, 0.41, or 0.42 g/L surfactin, respectively. All three genes are related to the metabolism of L-glutamate, whose acylation is the first step in the surfactin condensation reaction. Furthermore, these three genes were repressed in combination, and the strain with co-inhibition of yrpC and racE produced 0.75 g/L surfactin, which was 4.69-fold higher than that of the parent strain. In addition, the inhibition of bkdAA and bkdAB, which are related to the metabolism of L-leucine and L-valine, not only improved surfactin production but also increased the proportion of the C14 isoform. CONCLUSIONS: This study, to the best of our knowledge for the first time, systematically probed the regulatory effect of increasing the supply of amino acids on surfactin production. It provided an effective strategy and a new perspective for systematic studies on surfactin and other amino acid-derived chemicals.


Assuntos
Aminoácidos , Bacillus subtilis , Lipopeptídeos , Redes e Vias Metabólicas/genética , Tensoativos/metabolismo , Aminoácidos/genética , Aminoácidos/metabolismo , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Escherichia coli/genética , Lipopeptídeos/biossíntese , Lipopeptídeos/genética
13.
Nat Commun ; 10(1): 2270, 2019 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-31118411

RESUMO

Excellent catalytic activity, high stability and easy recovery are three key elements for fabricating efficient photocatalysts, while developing a simple method to fabricate such photocatalysts with these three features at the same time is highly challenging. In this study, we successfully synthesized double-shelled hollow rods (DHR) assembled by nitrogen (N) and sulfur (S)-codoped carbon coated indium(III) oxide (In2O3) ultra-small nanoparticles (N,S-C/In2O3 DHR). N,S-C/In2O3 DHR exhibits remarkable photocatalytic activity, high stability and easy recovery for oxidative hydroxylation reaction of arylboronic acid substrates. The catalyst recovery and surface area were well balanced through improved light harvesting, contributed by concurrently enhancing the reflection on the outer porous shell and the diffraction in the inside double-shelled hollow structure, and increased separation rate of photogenerated carriers. Photocatalytic mechanism was investigated to identify the main reactive species in the catalytic reactions. The electron separation and transfer pathway via N,S-codoped graphite/In2O3 interface was revealed by theoretical calculations.

14.
Small ; 15(22): e1901024, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31026129

RESUMO

Achieving highly efficient hierarchical photocatalysts for hydrogen evolution is always challenging. Herein, hierarchical mesoporous NiO@N-doped carbon microspheres (HNINC) are successfully fabricated with ultrathin nanosheet subunits as high-performance photocatalysts for hydrogen evolution. The unique architecture of N-doped carbon layers and hierarchical mesoporous structures from HNINC could effectively facilitate the separation and transfer of photo-induced electron-hole pairs and afford rich active sites for photocatalytic reactions, leading to a significantly higher H2 production rate than NiO deposited with platinum. Density functional theory calculations reveal that the migration path of the photo-generated electron transfer is from Ni 3d and O 2p hybrid states of NiO to the C 2p state of graphite, while the photo-generated holes locate at Ni 4s and Ni 4p hybrid states of NiO, which is beneficial to improve the separation of photo-generated electron-hole pairs. Gibbs free energy of the intermediate state for hydrogen evolution reaction is calculated to provide a fundamental understanding of the high H2 production rate of HNINC. This research sheds light on developing novel photocatalysts for efficient hydrogen evolution.

15.
Nanomicro Lett ; 11(1): 1, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30687730

RESUMO

Porous structures offer highly accessible surfaces and rich pores, which facilitate the exposure of numerous active sites for photocatalytic reactions, leading to excellent performances. Recently, metal-organic frameworks (MOFs) have been considered ideal precursors for well-designed semiconductors with porous structures and/or heterostructures, which have shown enhanced photocatalytic activities. In this review, we summarize the recent development of porous structures, such as metal oxides and metal sulfides, and their heterostructures, derived from MOF-based materials as catalysts for various light-driven energy-/environment-related reactions, including water splitting, CO2 reduction, organic redox reaction, and pollution degradation. A summary and outlook section is also included.

16.
Biomed Chromatogr ; 33(2): e4411, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30357881

RESUMO

Alum-processing is a traditional method to attenuate the toxicity of Pinelliae Rhizoma (tubers of Pinellia ternate, PT). The present study aimed at investigating the chemical and cytotoxic changes during alum processing. Metabolomic profiles of raw and alum-processed PT were studied based on ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry. More than 80 chemicals in positive MS mode and 40 chemicals in negative MS mode, such as organic acids, amino acids, glucosides and nucleosides, were identified after multivariate statistical analysis, including principal component analysis and orthogonal partial least-square discriminant analysis. Almost all of the identified chemical markers were significantly decreased ~10- to 100-fold after alum processing. Meanwhile, the correlations between the chemical markers were assimilated to a positive coefficient from disorderly distribution during the processing. Raw PT extracts could inhibit the proliferation of human carcinoma cells (HCT-116, HepG2, and A549) at the rate of 40.5, 24.8 and 31.6% more strongly than processed PT. It was concluded that the alum processing of PT could decrease the number of actively water-soluble principles at the same time as decreasing toxicity. Given the water-insoluble property of toxic calcium oxalate raphides in PT, we suggest that a more scientific processing method should be sought.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Medicamentos de Ervas Chinesas/análise , Metaboloma/fisiologia , Metabolômica/métodos , Pinellia/metabolismo , Compostos de Alúmen/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Composição de Medicamentos , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/farmacologia , Humanos , Espectrometria de Massas
17.
ACS Synth Biol ; 8(1): 70-81, 2019 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-30543412

RESUMO

Menaquinone-7 (MK-7), a valuable vitamin K2, plays an important role in the prevention of osteoporosis and cardiovascular calcification. We chose B. subtilis 168 as the chassis for the modular metabolic engineering design to promote the biosynthesis of MK-7. The biosynthetic pathway of MK-7 was categorized into four modules, namely, the MK-7 pathway (Module I), the shikimate (SA) pathway (Module II), the methylerythritol phosphate (MEP) pathway (Module III), and the glycerol metabolism pathway (Module IV). Overexpression of menA (Module I) resulted in 6.6 ± 0.1 mg/L of MK-7 after 120 h fermentation, which was 2.1-fold that of the starting strain BS168NU (3.1 ± 0.2 mg/L). Overexpression of aroA, aroD, and aroE (Module II) had a negative effect on the synthesis of MK-7. Simultaneous overexpression of dxs, dxr, yacM, and yacN (Module III) enabled the yield of MK-7 to 12.0 ± 0.1 mg/L. Moreover, overexpression of glpD (Module IV) resulted in an increase of the yield of MK-7 to 13.7 ± 0.2 mg/L. Furthermore, deletion of dhbB reduced the consumption of the intermediate metabolite isochorismate, thus promoting the yield of MK-7 to 15.4 ± 0.6 mg/L. Taken together, the final resulting strain MK3-MEP123-Gly2-Δ dhbB with simultaneous overexpression of menA, dxs, dxr, yacM-yacN, glpD and deletion of dhbB enabled the yield of MK-7 to 69.5 ± 2.8 mg/L upon 144 h fermentation in a 2 L baffled flask.


Assuntos
Bacillus subtilis/metabolismo , Engenharia Metabólica/métodos , Vitamina K 2/análogos & derivados , Bacillus subtilis/genética , Vias Biossintéticas/fisiologia , Ácido Chiquímico/metabolismo , Vitamina K 2/metabolismo
18.
Chemistry ; 25(12): 3053-3060, 2019 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30511767

RESUMO

It is desirable but challenging to design efficient micro-/nanoreactors for chemical reactions. In this study, we have fabricated mesoporous double-shelled hollow microreactors composed of N-doped-C-coated ultrafine In2 O3 nanoparticles [N-C/In2 O3 HD (hollow dodecahedron)] by the thermolysis of a dodecahedral In-based framework in Ar atmosphere. The obtained N-C/In2 O3 HD exhibited excellent activity in the photocatalytic oxidative hydroxylation of a series of arylboronic acid substrates. This property can be attributed to its enhanced optical absorption and efficient separation of photo-generated electron-hole pairs, imparted by the unique structure and uniformly coated N-doped C layers. Furthermore, we found O2 .- to be the critical active species in the process of photocatalytic oxidative hydroxylation of arylboronic acids, and the formation mechanism of this radical is also proposed. Theoretical calculations further confirmed that the N-doped C layer serves as an electron acceptor and revealed the microscopic charge-carrier migration path through the In2 O3 /N-doped graphite interfaces. Thus, photo-generated electrons from hybrid states of In2 O3 , composed of In 5s and 2p orbitals, are transferred into the hybrid states of N-doped graphite, composed of C 2p and N 2p orbitals. The present study may be helpful for understanding and designing carbon-based micro-/nanoreactors for photocatalytic reactions, and may also be useful for investigating related micro-/nanoreactors.

19.
Arch Environ Contam Toxicol ; 75(4): 607-615, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30178131

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) have attracted great concern as global environmental pollutants. In this work, the quantitative structure-biodegradability relationship (QSBR) study has been done to predict the biodegradability of PAHs and develop the correlation between the biodegradability and the molecular structures. The structural chemistry and quantum chemistry descriptors were used to represent molecular structures. Three in silico modeling methods, i.e., multiple linear regression (MLR), radial basis function neural network, and back-propagation artificial neural network (BPANN), are utilized to construct the linear and nonlinear prediction models and provide some insights into the structural characteristics affecting the biodegradability of PAHs. The stability of these QSBR models was tested by leave-one-out cross-validation, and the cross-validated correlation coefficients (q2) were 0.6109, 0.6887, and 0.6586, respectively. The correlation coefficients (R2) of the three models for the training set were 0.7811, 0.8883, and 0.9667, respectively. The comparison of the three models showed that the BPANN model produced a statistically more significant model than the other two models. On the basis of molecular structure, the dominant molecular structure descriptor affecting biodegradability of PAHs were analyzed and discussed.


Assuntos
Poluentes Ambientais/metabolismo , Modelos Teóricos , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Biodegradação Ambiental , Simulação por Computador , Poluentes Ambientais/química , Modelos Lineares , Estrutura Molecular , Hidrocarbonetos Policíclicos Aromáticos/química
20.
Chem Commun (Camb) ; 54(65): 8991-8994, 2018 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-29963660

RESUMO

P-Doped carbons, prepared by carbonizing phosphoric acid-treated cellulose, exhibit high catalytic activity in metal-free aerobic oxidation of benzyl alcohol to benzaldehyde (99.7% yield) in water under air. A high turnover frequency is obtained due to the doped P-species of C3PO, identified via experiments and DFT calculations.

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