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Electron transfer plays an important role in determining the energy conversion efficiency of energy devices. Nitrogen-coordinated single metal sites (M-N

Flame in situ synthesis is regarded as a facile technique to fabricate one-dimensional (1D) nanomaterials with the advantages of simple operation, shorter duration, and scale production. This work ...

Catalytic combustion has become a promising technology to address the accelerating volatile organic compounds (VOCs) emissions. In this work, cobalt modified ZSM-5 zeolite catalysts (3–18 wt % Co) ...

Transition metals supported on nitrogen doped carbon materials are a class of promising electrochemical catalysts toward electrochemical CO2 reduction reactions (CO2RR) that have exhibited excellent catalytic performance. Herein, M–N4 (M = Fe, Co and Ni) coordination structures embedded in carbon nanotubes (CNTs) were constructed to explore detailed mechanisms as electrocatalysts for CO2RR via density functional theory (DFT) calculations. Nitrogen atoms of coordination structures rather than only single transition metal atoms were demonstrated to be effective active sites toward CO2RR. For two possible pathways of the first step, forming *COOH or *OCHO, according to the catalytic activity of nitrogen atoms to the H atom, *COOH generation was facilitated in terms of kinetics over *OCHO in three systems. Meantime, it is suggested that the products of electrochemical CO2RR on the three catalysts are heavily dependent on the interaction of CO and the catalysts. Ni–N4/CNT exhibits a considerable selectivity to CO due to the weak interaction of CO and the substrates with a limiting potential of 1.79 V. On the contrary, CO prefers to remain on Fe–N4/CNT due to the strong binding energy of CO adsorbed on Fe–N4/CNT. Then the CO of the Fe–N4/CNT system undergoes further hydrogenation to produce CH3OH and CH4 at the same limiting potential of 0.68 V, indicating that there is no distinct selectivity in forming CH3OH and CH4. Nevertheless, the limiting potentials of CO, CH3OH and CH4 on Co–N4/CNT are totally different, 0.43 V, 0.56 V and 0.87 V, respectively. In particular, CO2RR to CO on Co–N4/CNT has the lowest potential limit. Thus, Co–N4/CNT has a considerable potential as the catalyst for electrochemical CO2RR. In addition, the catalysts of Ni single atoms, unsaturated coordination with nitrogen atoms, edge-anchored on CNTs were investigated for their activity for the CO2RR. Our comprehensive understanding of M–N4/CNT materials may be instructive and meaningful to design advanced catalysts from nonprecious metals for electrochemical CO2RR.

Catalytic combustion is a promising technology to improve combustion efficiency and reduce environmental pollutions. Both CO2 and vinyl radical (C2H3) are important species and give rise to environmental concerns. It is meaningful to investigate the combustion reaction CO2 + C2H3 under catalytic combustion, which helps to mitigate environmental damage. In this context, the theoretical study of chemical reaction kinetics of CO2 and C2H3 on Pd(1 0 0) and Cu(1 0 0) was carried out. Compared with conventional gas-phase combustion reaction, catalytic combustion has only two reaction paths, producing CO + CH2CHO and C2H2 + OCHO, respectively. The catalysts show superior performance in decomposition reactions, with Pd(1 0 0) in particular greatly reducing the energy barrier for the formation of CO + CH2CHO. And Pd(1 0 0) is preferred to form CO and CH2CHO rather than C2H2 and OCHO which are favorable in gas-phase reaction. In addition, the kinetic parameters of reaction CO2 + C2H3 on Pd(1 0 0) are obtained based on transition state theory. The results indicate that the formation of CH2CHO and CO dominates the reaction CO2 + C2H3. This work investigates the mechanism of reaction of CO2 and C2H3 on Pd(1 0 0) and Cu(1 0 0), paving the way for further research on the catalytic combustion mechanism and the regulation of pollutant emissions.

Polycyclic aromatic hydrocarbons (PAHs) as precursors of soot, have been one of intensive concerns of human health and environmental contamination. G3(MP2,CC)//B3LYP theory has been widely used for prediction of PAHs growth. It is, however, a computational challenge for studying fairly large PAHs formation using this method. Herein, an ONIOM[G3(MP2,CC)//B3LYP:DFT] method, a two-layer composite ab inito molecular-orbital theory, was developed where the high layer of the real reaction systems is treated with G3(MP2,CC)//B3LYP and low layer is dealt with hybrid density functional B3LYP method. To evaluate the performance of the ONIOM method on PAHs growth, the potential energy surfaces (PESs) of naphthalene growth obtained from ONIOM method were compared with that from G3(MP2,CC)//B3LYP based on hydrogen-abstraction/C2H2-addition (HACA) mechanism. It is found that the results of ONIOM method are in good agreement with the results from G3(MP2,CC)//B3LYP method with mean energy error of −0.24 kcal/mol. After calculating the PESs of anthracene, phenanthrene, pyrene, and coronene growth based on HACA mechanism by ONIOM method, it is found that the computational costs of ONIOM method decrease significantly compared with G3(MP2,CC)//B3LYP method as the numbers of aromatic rings in PAHs increases. At the same time, ONIOM method maintains accurate prediction of PAHs growth. At last, time-dependent RRKM-based master equations using the obtained energy from ONIOM method were solved to calculate the pressure- and temperature-dependent rate coefficients of PAHs formations. Armed with this developed ONIOM method, more kinetics studies of PAHs growth may be carried out.

In this paper, chemical reaction kinetics at low temperatures on three different methyl crotonate (MC, C5H8O2) radicals with O2 were conducted via quantum chemical methods. The potential energy surfaces (PESs) for these reactions were investigated by M062x/6-311++G(d,p) and CBS-QB3 methods. The related rate coefficients also have been solved by master equations based on Rice-Ramsperger-Kassel-Marcus theory, predicting the competitive relationships over 300 to 1500 K and 0.001 to 100 atm. The calculated results indicated that the rate constants of O2 addition reaction at ester methylic site were higher than those at allylic sites, which showed that the conjugation effect caused by the C=C double bond has a crucial effect on the reaction process. Formation of initial adducts and intramolecular H-transfer reactions play a great role in the low temperature oxidation of MC. Furthermore, the mechanism of O2 addition to MC radicals was verified by the previous combustion model. The updated model did a good job to replicate the previous experimental results. This work not only provides the necessary rate constants for the reaction mechanism of MC combustion but also serves as a solid starting point for the further understanding of combustion kinetics of large molecule unsaturated biodiesels.

Clustering by fast search and find of density peaks (CFSFDP) is proposed to cluster the data by finding of density peaks. CFSFDP is based on two assumptions that: a cluster center is a high dense data point as compared to its surrounding neighbors, and it lies at a large distance from other cluster centers. Based on these assumptions, CFSFDP supports a heuristic approach, known as decision graph to manually select cluster centers. Manual selection of cluster centers is a big limitation of CFSFDP in intelligent data analysis. In this paper, we proposed a fuzzy-CFSFDP method for adaptively selecting the cluster centers, effectively. It uses the fuzzy rules, based on aforementioned assumption for the selection of cluster centers. We performed a number of experiments on nine synthetic clustering datasets and compared the resulting clusters with the state-of-the-art methods. Clustering results and the comparisons of synthetic data validate the robustness and effectiveness of proposed fuzzy-CFSFDP method.

Phototherapy is an important branch in the application of cancer therapy, having the advantages of low invasion, negligible toxicity, and convenience, which are rapidly developing in the pre-clinic and clinic therapy for cancer. Herein, a novel multifunctional nanocomposite containing polydopamine (PDA)@cobalt phytate (CoPA) with lactose acid (LA) grafting were successfully synthesized. The PDA core was used as the template for the formation of CoPA, and also endowed the obtained nanocomposite with photothermal imaging and photothermal therapy (PTT) to cancers. The CoPA shell possessed excellent dual photo-responsive abilities, not only induced the formation of singlet oxygen, but also catalyzed intracellular water-splitting to produce O2 in situ for enhancing photodynamic therapy (PDT) effect on tumor cells under laser irradiation. Furthermore, the lactose acid grafting endued the targeting ability to the synthesized nanocomposites for realizing specific targeted cancer therapy. The experiment results in vitro and in vivo both demonstrate that the designed PDA@CoPA-LA NCs have excellent synergistic PTT and PDT effect enhanced by in situ O2-generation with specific targeted performance, exhibiting great potential in the application for clinic cancer therapy.

Clustering by fast search and find of density peaks (DP) is a method in which density peaks are used to select the number of cluster centers. The DP has two input parameters: 1) the cutoff distance and 2) cluster centers. Also in DP, different methods are used to measure the density of underlying datasets. To overcome the limitations of DP, an Adaptive-DP method is proposed. In Adaptive-DP method, heat-diffusion is used to estimate density, cutoff distance is simplified, and novel method is used to discover exact number of cluster centers, adaptively. To validate the proposed method, we tested it on synthetic and real datasets, and comparison are done with the state of the art clustering methods. The experimental results validate the robustness and effectiveness of proposed method.

To determine the associations between maternal ethnicity and outcomes of infants born between 22 and 31 weeks' gestation and admitted to neonatal intensive care units in New South Wales and the Australian Capital Territory, Australia, between 1995 and 2006.De-identified perinatal and neonatal outcome data for 10 267 infants were examined. There were 8629 (84.0%) Caucasian, 922 (9.0%) Asian, 439 (4.3%) indigenous, 127 (1.2%) Polynesian and Maori (PAM) and 150 (1.5%) infants of other maternal ethnicities (excluded from study). Caucasians were the referent for all comparisons.Infants of indigenous mothers were less likely to receive antenatal steroids and three times as likely to be born in non-tertiary hospitals (OR 3.28, 95% CI 2.59 to 4.16, p0.001). PAM infants were more likely to have Apgar scores7 at 5 min of age (1.76, 95% CI 1.16 to 2.67, p0.01). Asian infants had lower birth weight (mean±SD 44.7±27.9, p0.001) and head circumference percentiles (47.8±29.0, p0.001), were more likely to be small for gestational age (1.53, 95% CI 1.25 to 1.88, p0.001), less likely to have hyaline membrane disease (0.78, 95% CI 0.68 to 0.90, p0.001) but had a higher risk of severe retinopathy of prematurity (1.52, 95% CI 1.11 to 2.07, p0.01). Ethnicity did not influence infant mortality.Neonatal growth characteristics and morbidity but not mortality are influenced by maternal ethnicity. Of concern is the risk of low Apgar scores in PAM infants and non-tertiary births of indigenous infants. Review of perinatal care for certain vulnerable ethnic populations is recommended due to the rapidly changing ethnic compositions of many countries around the world.