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Background and purpose: The incidence of ductal carcinoma in situ (DCIS) has increased annually with the popularity of mammography screening. However, current treatment strategies are mostly based on the results of prospective randomized clinical trials in western countries. This study aimed to explore the clinical characteristics, recurrence patterns and prognostic factors of Chinese DCIS patients, hoping to optimize clinical decision-making. Methods: Medical records of 1 185 DCIS patients treated in Fudan University Shanghai Cancer Center from January 2008 to January 2017 were retrospectively analyzed. The local recurrence-free survival (LRFS) rate, disease-free survival (DFS) rate and overall survival (OS) rate were calculated using the Kaplan-Meier method. Univariate and multivariate analyses were performed using the COX proportional hazards regression model. Results: With a median follow-up of 61 months, 50 treatment failure events were observed, including 16 locoregional recurrences, 30 contralateral breast cancer events and 4 distant metastases. The 5-year OS rate, LRFS rate and DFS rate were 99.9%, 98.7% and 96.6%, respectively. In the multivariate analysis, the positive status of human epidermal growth factor receptor 2 (HER2) was related to higher risk of local recurrence and the LRFS rate was poor (P=0.029). Conclusion: The patient with DCIS was associated with favorable prognosis. HER2 positivity was the risk factor for poor LRFS.

The relationships between structures and performances of polynitroadamantanes (PNAs) were studied for high energy density materials (HEDM). Results showed that, when the number of NO(sub 2) groups, n, is equal to or more than eight, the corresponding PNAs meet the criteria of an HEDM.

Comparative studies on the four AtiO3 compounds are conducted to investigate the different ferroelectric behaviors of AtiO3 on the basis of the experimental and theoretically optimized lattice structures. The potential energy surfaces (PESs) show Ti displacements in CaTiO3 and SrTiO3 result in single-well potential whereas in BaTiO2 and PbTiO3 they produce double-well potential.

Multicomponent diastereoselective synthesis is still very difficult to achieve in photoredox catalysis. Here, we report a green and reliable strategy for the diastereoselective synthesis of ß-amido sulfones through organophotoredox catalytic four-component radical-polar crossover cascade reactions. This transformation features excellent atom-, step-, and redox economy and diastereoselectivity. Moreover, DFT calculation studies were performed to provide some insights into the origin of diastereoselectivity. [ABSTRACT FROM AUTHOR]

Gold nanoparticles play a key role in catalytic processes. We investigated the kinetics of stepwise hydrogenation of acrolein on Au20 cluster model and compared with that on Au(110) surface. The rate-limiting step barrier of C==C reduction is about 0.5 eV higher than that of C==O hydrogenation on Au(110) surface. On Au20 nanoparticle, however, the energy barrier of the rate-determining step for C==C hydrogenation turns out to be slightly lower than the value for the C==O reduction. The selectivity difference on the two substrate models are attributed to different adsorption modes of acrolein: via the C==C on Au20, compared to through both C==C and C==O on Au(110). The preference switch implies that the predicted selectivity of competitive hydrogenation depends on substrate model sensitively, and particles with more low-coordinated Au atoms than flat surfaces are favorable for C==C hydrogenation, which is in agreement with experimental result. [ABSTRACT FROM AUTHOR]

We studied the adsorption of C2H4 and CH2O on the gold clusters Aun (n=1–5) in various adsorption modes using density functional theory PW91 functional. We found that the binding energies of π-C2H4 and π and O-σ modes of CH2O increase first and then decrease with the cluster size. Natural bonding orbital (NBO) analyses reveal that the donor-acceptor interaction plays an important role in these adsorption complexes and there is a nice linear relationship between the calculated binding energy and the stabilization energy estimated with second-order perturbation theory in the framework of NBO analysis. It is demonstrated that the bonding interaction between adsorbates and clusters follows the di-σ>π>O-σ mode. However, due to adsorption induced structural deformation of adsorbates and clusters, the binding energies of different adsorption modes are comparable. It is shown that C2H4 interacts more strongly with the clusters than CH2O does and that the previously assigned adsorption mode of C2H4 on Au/MgO may not be the π modes, but the C-σ configuration. [ABSTRACT FROM AUTHOR]

The adsorption and dissociation of H2 on the neutral and charged gold clusters Aunm(m=0,±1; n=1–6) is investigated using the density functional theory PW91 functional. H2 interacts very weakly with Aun-1, whereas the interaction with Aun+1 is relatively strong. The binding energies on neutral clusters are between those on the cationic and anionic systems. The binding energy decreases monotonically with the size increase of the cationic clusters while it goes up first and then goes down on the neutral systems with the maximum value of 0.78 eV at Au3. Au cations show no propensity for the dissociation barrier reduction and are thermodynamically unfavorable for the dissociation. For the first time we find that H2 dissociation involves valley-ridge inflection points on some clusters. Our results indicate that H2 dissociates facilely at low temperatures on both neutral and cationic Au4 and Au5. The phenomenon that H2 dissociation was not observed experimentally is not due to the higher dissociation barrier and weak binding of H2. We also show that the coordination number of the Au atom may not play a determining role in H2 dissociation. [ABSTRACT FROM AUTHOR]

The adsorption and dissociation of H2 on the neutral and charged gold clusters Aunm(m=0,±1; n=1–6) is investigated using the density functional theory PW91 functional. H2 interacts very weakly with Aun-1, whereas the interaction with Aun+1 is relatively strong. The binding energies on neutral clusters are between those on the cationic and anionic systems. The binding energy decreases monotonically with the size increase of the cationic clusters while it goes up first and then goes down on the neutral systems with the maximum value of 0.78 eV at Au3. Au cations show no propensity for the dissociation barrier reduction and are thermodynamically unfavorable for the dissociation. For the first time we find that H2 dissociation involves valley-ridge inflection points on some clusters. Our results indicate that H2 dissociates facilely at low temperatures on both neutral and cationic Au4 and Au5. The phenomenon that H2 dissociation was not observed experimentally is not due to the higher dissociation barrier and weak binding of H2. We also show that the coordination number of the Au atom may not play a determining role in H2 dissociation. [ABSTRACT FROM AUTHOR]

The DFT-PW91 slab model approach is employed to investigate the influence of aggregation, surface defects, and contaminant oxygen on water dissociation on Cu(110) at low temperatures. The dissociation barriers of water in various aggregate states are calculated in the range of 60–75 kJ/mol on the clean surfaces, in nice agreement with the experimentally determined values. It is revealed that the aggregation of water shows no propensity to reduce the activation barrier for the O–H bond breaking on Cu(110), at variance with the water chemistry on Ru(0001). The calculated activation energy on Cu(211) which is the most active stepped surface investigated is equal to the value on the (110) surface, indicating that the hydroxyl groups observed on Cu(110) at low temperatures may not stem from surface defects. The coadsorbed oxygen, whether as a “spectator” or a “participant,” facilitates the water dissociation both kinetically and thermodynamically. [ABSTRACT FROM AUTHOR]

Density functional slab model calculations are used to study the decomposition of formaldehyde, a key intermediate in methanol decomposition and steam reforming reactions, on planar surfaces of Pd, Cu and PdZn as well as on a stepped surface of PdZn. The experimentally observed small amount of CO, formed during steam reforming of methanol on the Pd/ZnO catalyst, is ascribed to occur at metallic Pd species of the catalyst or at defect sites of PdZn alloy.

The density functional periodic slab-model is approach is applied to investigate the two routes of CH3O decomposition on PdZn(221) surfaces that expose Pd, (221)Pd, and Zn, (221)Zn, steps. The binding energies on stepped (221)Pd and (221)Zn substrate preferring Pd-dominated sites feature the strongest binding on (221)Pd, while for adsorbates favoring Zn-dominated sites the adsorption interaction is the strongest on the (221)Zn slab.

The plane-wave pseudopotential method and the LCAO quantum chemical approach in the framework of density functional theory (DFT) are used to investigate the ferroelectricity of BaTiO3. The DFT calculations show a lattice constant of 3.99 Armstrong and dielectric constant of 5.74 for the cubic BaTiO3.

To explore the effect of surface contaminants on water chemistry at metallic surfaces, adsorption and decomposition of water monomers on clean and X/Pd(111)(X = C, N and O) surfaces are investigated based on density functional theory calculations. It is revealed that H2O binds to Pd(111) surface primarily through the mixing of its 1b1 with the Pd 4dz2 state. A charge accumulation between the oxygen atom of water and the bound Pd atom is calculated, which is found to be relevant to the H2O–Pd interaction. Water adsorption results in a reduction of surface work function and the polarization of the X 2p states. The O–H bond scission of H2O on the clean Pd(111) is an energy unfavorable process. In the case of X-assisted O–H bond breaking on X/Pd(111) surfaces, however, the reaction barrier tends to be lower than that on the clean surface and decreases from C/Pd(111) to O/Pd(111). In particular, water decomposition is found to become feasible on O/Pd(111), in agreement with the experimental observations. The calculated barrier is demonstrated to be correlated linearly with the density of X 2p states at the Fermi level. A thorough energy analysis demonstrates that the following geometrical and electronic factors favor the barrier reduction on X/Pd(111) with respect to water decomposition on clean Pd(111): (i) the less deformed structure of water in TS; (ii) the decreased bonding competition between the fragments OH and H. The remarkable decrease of the barrier on O/Pd(111) is revealed to be due to the largest stabilization of the split H atom and the least deformation of water in the TS. [ABSTRACT FROM AUTHOR]