Mechanical and Electrical Conductivity Properties of Graphene/Cu Interfaces: A Theoretical Insight.

For graphene/copper (Gr/Cu) composites, achieving high-quality interfaces between Gr and Cu (strong interfacial bonding strength and excellent electron transport performance) is crucial for enabling their widespread applications in electronic devices. This study employs first-principles calculations and the nonequilibrium Green's function method to systematically investigate the mechanical and electrical conductivity properties of Cu(111)/Gr/Cu(111) interfaces with various stacking sequences and different forms of Gr. For these interface systems, the binding energy, separation work, charge transfer, and electrical conductivity across the interface were obtained. The results show that the top-fcc interface exhibits superior interfacial properties, characterized by relatively high binding energy (-3.00 eV/C atom) and separation work (≥0.78 J/m2), a small interfacial distance (2.85 Å), and enhanced electron transport capacity (2.12 G0/nm2). A bilayer form of Gr significantly reduces electronic conductance across the Gr/Cu interface by nearly 2.46 orders of magnitude. Furthermore, point defects in Gr, especially single-vacancy defects, disrupt the traditional trade-offs between mechanical and electrical performance, simultaneously enhancing mechanical performance by 7.50-124.36% and electrical performance by 33.02%. Additionally, stress mechanisms have been proposed to further enhance the interfacial electrical conductivity of Gr/Cu composites. The present study provides a theoretical basis for exploring the engineering applications of Gr/Cu composite materials.

Local environmental engineering for highly stable single-atom Pt1/CeO2catalysts: first-principles insights.

Single-atom Pt1/CeO2catalysts may cope with the high cost and durability issues of fuel cell electrocatalysts. In the present study, the stability and underlying interaction mechanisms of the Pt1/CeO2system are systematically investigated using first-principles calculations. The Pt adsorption energy on CeO2surfaces can be divided into chemical interaction and surface deformation parts. The interaction energy, mainly associated with the local chemical environment, i.e. the number of Pt-O bonds, plays a major role in Pt1/CeO2stability. When forming a Pt-4O configuration, the catalytic system has the highest stability and Pt is oxidized to Pt2+. An electronic metal-support interaction mechanism is proposed for understanding Pt1/CeO2stability. In addition, our calculations show that the Pt1/CeO2(100) system is dynamically stable, and the external O environment can promote the further oxidation of Pt to Ptn+(2 ≤n< 4). The present study provides useful guidance for the experimental development of highly stable and efficient electrocatalysts for fuel cell applications.

The Universal Super Cation-Conductivity in Multiple-cation Mixed Chloride Solid-State Electrolytes.

As exciting candidates for next-generation energy storage, all-solid-state lithium batteries (ASSLBs) are highly dependent on advanced solid-state electrolytes (SSEs). Here, using cost-effective LaCl3 and CeCl3 lattice (UCl3 -type structure) as the host and further combined with a multiple-cation mixed strategy, we report a series of UCl3 -type SSEs with high room-temperature ionic conductivities over 10-3  S cm-1 and good compatibility with high-voltage oxide cathodes. The intrinsic large-size hexagonal one-dimensional channels and highly disordered amorphous phase induced by multi-metal cation species are believed to trigger fast multiple ionic conductions of Li+ , Na+ , K+ , Cu+ , and Ag+ . The UCl3 -type SSEs enable a stable prototype ASSLB capable of over 3000 cycles and high reversibility at -30 °C. Further exploration of the brand-new multiple-cation mixed chlorides is likely to lead to the development of advanced halide SSEs suitable for ASSLBs with high energy density.

The Facile Three-Dimensional Printing of the Composite of Copper Nanosized Powder and Micron Powder with Enhanced Properties.

Three-dimensional (3D) printing of Cu items is a new way to build up the structured Cu materials, but 3D printing of Cu items is usually a challenge because of the high melting point, high thermal conductivity, and high light reflection rate of Cu material. In this study, the composite of Cu microspheres powder and Cu nanoparticles (micro/nano Cu powder) is used to realize the 3D printing of Cu items with the selective laser melting technology. The sintering temperature and the thermal conductivity of micro/nano Cu powder are evidently decreased due to Cu nanoparticles' addition in the micron Cu powder. The results reveal that the 3D printing of 50%/50% micro/nano Cu powder needs laser power range of 100-240 W, which is in contrast to 200-340 W for 3D printing of 100% Cu microspheres powder. Furthermore, the conductivity, mechanical strength, and density of 3D-printed Cu items are improved with the addition of Cu nanoparticles into the micron Cu powder. The increasement of 34% on electrical conductivity and 17% on tensile strength are reached by the addition of 50% Cu nanoparticles with the laser power of 240 W.

Improving the HCHO Sensing Selectivity on Ag-Doped Graphene by Oxygen Functionalization: A First-Principles Study.

Graphene-based sensors typically fail in the selectivity of target gas detection when exposed to complex and multicompound atmospheres. We have thoroughly compared the adsorptions of various interfering gases (CO, NH3, CH4, C2H2, C2H4, CH3OH, and CH3Cl) with target HCHO on AgG and AgOG by first-principles simulations. The results demonstrate that AgG shows a poor selectivity for HCHO detection and an oxygen functionalized one can improve the selectivity by enhancing the adsorption strength of HCHO and weakening those of other gas molecules. Moreover, the sensing properties of the AgOG sensors are evaluated by the NEGF method, and the predicted HCHO sensing responses are 76 and 32% along the armchair and zigzag directions, respectively. The present work helps shed some light on designing graphene-based sensing materials with high selectivity.

Stress and Defect Effects on Electron Transport Properties at SnO2/Perovskite Interfaces: A First-Principles Insight.

The structural and electronic properties of interfaces play an important role in the stability and functionality of solar cell devices. Experiments indicate that the SnO2/perovskite interfaces always show superior electron transport efficiency and high structural stability even though there exists a larger lattice mismatch. Aiming at solving the puzzles, we have performed density-functional theory calculations to investigate the electronic characteristics of the SnO2/perovskite interfaces with various stresses and defects. The results prove that the PbI2/SnO2 interfaces have better structural stability and superior characteristics for the electron transport. The tensile stress could move the conduction band minimum (CBM) of CH3NH3PbI3 upward, while the compressive stress could move the CBM of SnO2 downward. By taking into account the stress effect, the CBM offset is 0.07 eV at the PbI2/SnO2 interface and 0.28 eV at the MAI/SnO2 interface. Moreover, our calculations classify VI and Ii at the PbI2/SnO2 interface and Sn-I, Ii and Sni at the MAI/SnO2 interface as harmful defects. The Ii defects are the most easily formed harmful defects and should be avoided at both interfaces. The calculated results are in agreement with the available experimental observations. The present work provides a theoretical basis for improving the stability and photovoltaic performance of the perovskite solar cells.

Tunable formaldehyde sensing properties of palladium cluster decorated graphene.

The ability to tune the adsorption strength of the targeted gas on sensing materials is crucial for sensing applications. By employing first-principles calculations the adsorption and sensing properties of HCHO on small Pd n (n = 1-6) cluster decorated graphene have been systematically investigated. The adsorption energy is found to depend on the size of the Pd n cluster and can be tuned in a wide range from -0.68 eV on Pd(111) to -1.98 eV on the Pd3/graphene system. We also find that the Pd n /graphene (n = 5 and 6) systems have an appropriate adsorption energy for HCHO gas sensing. The current-voltage curves are calculated by the non-equilibrium Green's function method for the two-probe nano-sensor devices along both the armchair and zigzag directions. The devices constructed with Pd n /graphene (n = 5 and 6), having the highest absolute response over 20% at small voltages, should be applicable for HCHO detection. This work provides a theoretical basis for exploring potential applications of metal cluster decorated graphene for gas sensing.

Treeio: An R Package for Phylogenetic Tree Input and Output with Richly Annotated and Associated Data.

Phylogenetic trees and data are often stored in incompatible and inconsistent formats. The outputs of software tools that contain trees with analysis findings are often not compatible with each other, making it hard to integrate the results of different analyses in a comparative study. The treeio package is designed to connect phylogenetic tree input and output. It supports extracting phylogenetic trees as well as the outputs of commonly used analytical software. It can link external data to phylogenies and merge tree data obtained from different sources, enabling analyses of phylogeny-associated data from different disciplines in an evolutionary context. Treeio also supports export of a phylogenetic tree with heterogeneous-associated data to a single tree file, including BEAST compatible NEXUS and jtree formats; these facilitate data sharing as well as file format conversion for downstream analysis. The treeio package is designed to work with the tidytree and ggtree packages. Tree data can be processed using the tidy interface with tidytree and visualized by ggtree. The treeio package is released within the Bioconductor and rOpenSci projects. It is available at https://www.bioconductor.org/packages/treeio/.

Small cell carcinoma of the uterine cervix: a multi-institutional experience.

OBJECTIVE: Small cell carcinoma of the uterine cervix is associated with a poor prognosis with a median overall survival that is quite low. The aim of this study was to determine the clinico-pathologic characteristics that have an impact on survival in patients with small cell carcinoma of the uterine cervix. METHODS: A total of 93 patients were involved in this retrospective study. Inclusion criteria were patients diagnosed with histopathologically confirmed small cell carcinoma of the uterine cervix and then later treated at three participating centers, between June 2001 and March 2015. Those without complete available follow-up records were excluded. The endpoints of this study were disease-free survival and overall survival. Kaplan-Meier and Cox regression methods were used for analyses. RESULTS: There were statistical differences in overall survival between patients in early and in advanced stages by using the 2009 International Federation of Gynecology and Obstetrics (FIGO) clinical stage. There were 75 patients with FIGO stage I to IIA (56 patients stage I, 17 patients stage IIA, and two patients stage IB or IIA because of uncertainty as to whether the fornix was involved); and 18 patients with FIGO stage IIB and above (10 patients IIB stage, five patients stage III, and three patients stage IV). Among the 76 patients who had surgery, 73 (96%) had a radical hysterectomy with pelvic lymph node dissection and three (4%) patients had a simple hysterectomy without lymph node dissection. For early-stage patients, the 5 year disease-free survival rate was 52.7% compared with 32.4% in the advanced stage group (p=0.022). The disease-free survival for the early-stage group was 64.4% compared with 36.7% in the advanced-stage group (p=0.047). For factors affecting overall survival, age at diagnosis, tumor homology, tumor size, depth of stromal invasion, lymph node involvement, and treatment modality failed to reach significance in both univariate and multivariate analysis. CONCLUSION: FIGO stage was a prognostic factor impacting survival-both overall survival and disease-free survival. Age at diagnosis, tumor histology (pure or mixed), tumor size, depth of stromal invasion, lymph node involvement, and treatment modality did not have an impact on overall survival.

Single-atom Sn-Zn pairs in CuO catalyst promote dimethyldichlorosilane synthesis.

Single-atom catalysts are of great interest because they can maximize the atom-utilization efficiency and generate unique catalytic properties; however, much attention has been paid to single-site active components, rarely to catalyst promoters. Promoters can significantly affect the activity and selectivity of a catalyst, even at their low concentrations in catalysts. In this work, we designed and synthesized CuO catalysts with atomically dispersed co-promoters of Sn and Zn. When used as the catalyst in the Rochow reaction for the synthesis of dimethyldichlorosilane, this catalyst exhibited much-enhanced activity, selectivity and stability compared with the conventional CuO catalysts with promoters in the form of nanoparticles. Density functional theory calculations demonstrate that single-atomic Sn substitution in the CuO surface can enrich surface Cu vacancies and promote dispersion of Zn to its atomic levels. Sn and Zn single sites as the co-promoters cooperatively generate electronic interaction with the CuO support, which further facilitates the adsorption of the reactant molecules on the surface, thereby leading to the superior catalytic performance.

Influence of Mixed Valence on the Formation of Oxygen Vacancy in Cerium Oxides.

Ceria is one of the most important functional rare-earth oxides with wide industrial applications. Its amazing oxygen storage/release capacity is attributed to cerium's flexible valence conversion between 4+ and 3+. However, there still exists some debate on whether the valence conversion is due to the Ce-4f electron localization-delocalization transition or the character of Ce-O covalent bonds. In this work, a mixed valence model was established and the formation energies of oxygen vacancies and electronic charges were obtained by density functional theory calculations. Our results show that the formation energy of oxygen vacancy is affected by the valence state of its neighboring Ce atom and two oxygen vacancies around a Ce4+ in CeO2 have a similar effect to a Ce3+. The electronic charge difference between Ce3+ and Ce4+ is only about 0.4e. Therefore, we argue that the valence conversion should be understood according to the adjustment of the ratio of covalent bond to ionic bond. We propose that the formation energy of oxygen vacancy be used as a descriptor to determine the valence state of Ce in cerium oxides.

Electrochemical Preparation and Post-treatment of Composite Porous Foam NiZn Alloy Electrodes with High Activity for Hydrogen Evolution.

Composite porous foam NiZn alloy electrodes with nano pore structure were prepared by the combination of eletrodeposition, heat treatment and HCl etching. The morphology of the electrodes was examined by scanning electron microscopy (SEM). And the component of the electrodes was analyzed by Energy Dispersive Spectrum (EDS). The specific surface area and pore size of the electrode were investigated by nitrogen adsorption. The phase constituents were analyzed by X ray diffraction (XRD), and the electrocatalytic characteristics for hydrogen evolution reaction of the electrodes in 30% (mass fraction) KOH solution were investigated by cathode polarization curve. The experimental results showed that the pores were formed on surface of the foam NiZn alloy electrodes after heat treatment at 600 °C, and with the etching by 10% HCl, nano layered structure was formed on the surface of the porous skeleton. Compared with the nickel foam, the surface area of the NiZn foam alloy electrode became larger, and the nano pore structure had good catalytic activity. At current density of 200 mA·dm-2, the hydrogen evolution overpotential of the NiZn foam alloy electrodes were reduced by 222 mV and 276 mV, respectively, through heat treatment of 600 °C and etching in 10% HCl solution, which indicated that the hydrogen evolution overpotential was effectively reduced because of the composite nano porous structure, while the activity of hydrogen evolution of the electrodes was obviously improved.

Synthesis, electronic structures, and photoluminescence properties of an efficient and thermally stable red-emitting phosphor Ca3ZrSi2O9:Eu3+,Bi3+ for deep UV-LEDs.

A series of red-emitting Ca3ZrSi2O9:Eu3+,xBi3+ phosphors was synthesized using a conventional high temperature solid-state reaction method, for the purpose of promoting the emission efficiency of Eu3+ in a Ca3ZrSi2O9 host. The site preference of Bi3+ and Eu3+ in the Ca3ZrSi2O9 host was evaluated by formation energy. The effects of Bi3+ on electronic structure, luminescent properties, and related mechanisms were investigated. The inner quantum yield of the optimized sample increased to 72.9% (x = 0.08) from 34.6% (x = 0) at 300 nm ultraviolet light excitation. The optimized sample (x = 0.08) also showed excellent thermal stability, and typically, 84.2% of the initial emission intensity was maintained when the temperature increased to 150 °C from 25 °C, which is much higher than that without Bi3+ doping (70.1%). The mechanisms of emission properties and thermal stability enhancement, as well as the redshift of the charge transfer band (CTB) induced by Bi3+ doping in the Ca3ZrSi2O9:Eu3+ phosphor, were discussed. This study elucidates the photoluminescence properties of Bi3+-doped Ca3ZrSi2O9:Eu3+ phosphor, and indicates that it is a promising luminescent material that can be used in ultraviolet light-emitting diodes.

Californium-252 neutron brachytherapy combined with external pelvic radiotherapy plus concurrent chemotherapy for cervical cancer: a retrospective clinical study.

BACKGROUND: Cervical cancer is the sixth most common cancer in Chinese women. A standard treatment modality for cervical cancer is the combination of surgery, chemotherapy, external-beam radiotherapy and intracavitary brachytherapy. The aim of this study was to retrospectively assess the long-term treatment outcomes of patients with cervical cancer who were treated with californium-252 neutron brachytherapy combined with external-beam radiotherapy plus concurrent chemotherapy. METHODS: We retrospectively analyzed the medical records of 150 patients with primary stages IB-IVB cervical cancer who received neutron brachytherapy combined with external-beam radiotherapy concurrently with cisplatin chemotherapy. All patients were followed up. Using an actuarial analysis, patient outcomes and treatment-related adverse effects were evaluated and compared. RESULTS: The median overall survival (OS) was 33.2 months. The 3-year progression-free survival rates for patients with stages I-II, III, and IV diseases were 81.0% (68/84), 65.0% (39/60), and 0% (0/6), respectively; the 3-year OS rates were 90.5% (76/84), 85.0% (51/60), and 16.7% (1/6), respectively. Vaginal bleeding was controlled within the median time of 4.0 days. One month after treatment, 97.3% of patients achieved short-term local control. The local recurrence rates for patients with stages I-II, III, and IV disease were 4.8% (4/84), 11.7% (7/60), and 33.3% (2/6), respectively, and the occurrence rates of distant metastasis were 16.7% (14/84), 25.0% (15/60), and 100.0% (6/6), respectively. Cancer stage, tumor size, and lymph node metastasis were identified as prognostic risk factors, but only lymph node metastasis was found to be an independent prognostic factor. The most common adverse effects during treatment were grades 1 and 2 irradiation-related proctitis and radiocystitis. CONCLUSION: For patients with cervical cancer, neutron brachytherapy combined with external-beam radiotherapy plus concurrent chemotherapy produces a rapid response and greatly improves local control and long-term survival rates with tolerable adverse effects.

Origin of Spectral Blue Shift of Lu3+-Codoped YAG:Ce3+ Phosphor: First-Principles Study.

Lu3+, with the smallest ionic radii in lanthanide ions, is an important and beneficial cation for tuning spectrum shifting toward a longer wavelength by ion substitution in many phosphors for solid-state lighting. However, in the Lu3+-substituted garnet system, the phosphor always has smaller lattice parameters and exhibits a shorter emission wavelength than other garnet phosphors. The mechanism of such a spectral blue shift induced by the Lu3+-codoped garnet phosphor is still unclear. In this study, the local and electronic structures of Lu3+-codoped and Lu3+-undoped YAG:Ce3+ phosphor have been studied by first-principles calculation to reveal the origin of the spectral blue shift. Our results provide a full explanation of the experimental data and the methodology, which is useful to understand and design garnet phosphors with tunable emission characteristics.

Understanding the surface segregation behavior of transition metals on Ni(111): a first-principles study.

The surface composition of an alloying system has an important impact on its catalytic and chemical properties. The segregation behavior of 3d, 4d and 5d transition metals on an Ni(111) surface has been investigated by performing first-principles calculations in the framework of density-functional theory with the generalized gradient approximation for the exchange-correlation functional. Our calculated surface segregation energies are in good agreement with the experimental data as well as with previous calculated results. Most importantly, we have made an attempt to correlate the surface segregation behavior with the surface energy difference between the alloying (solute) metal and the host metal, the elastic energy release, and the heat of solution of the alloying metal in the host metal. By doing so, we not only overcome the difficulties that empirical models encounter, but also clearly identify the importance of each contribution to the segregation behavior of an alloying metal. The present study provides valuable insight into the surface segregation behavior of solute atoms in alloying systems.

Correction: First-Principles Study of Mo Segregation in MoNi(111): Effects of Chemisorbed Atomic Oxygen. Materials 2016, 9, 5.

[This corrects the article DOI: 10.3390/ma9010005.].

ChIPseeker: an R/Bioconductor package for ChIP peak annotation, comparison and visualization.

UNLABELLED: ChIPseeker is an R package for annotating ChIP-seq data analysis. It supports annotating ChIP peaks and provides functions to visualize ChIP peaks coverage over chromosomes and profiles of peaks binding to TSS regions. Comparison of ChIP peak profiles and annotation are also supported. Moreover, it supports evaluating significant overlap among ChIP-seq datasets. Currently, ChIPseeker contains 15 000 bed file information from GEO database. These datasets can be downloaded and compare with user's own data to explore significant overlap datasets for inferring co-regulation or transcription factor complex for further investigation. AVAILABILITY AND IMPLEMENTATION: ChIPseeker is released under Artistic-2.0 License. The source code and documents are freely available through Bioconductor (http://www.bioconductor.org/packages/release/bioc/html/ChIPseeker.html).

DOSE: an R/Bioconductor package for disease ontology semantic and enrichment analysis.

SUMMARY: Disease ontology (DO) annotates human genes in the context of disease. DO is important annotation in translating molecular findings from high-throughput data to clinical relevance. DOSE is an R package providing semantic similarity computations among DO terms and genes which allows biologists to explore the similarities of diseases and of gene functions in disease perspective. Enrichment analyses including hypergeometric model and gene set enrichment analysis are also implemented to support discovering disease associations of high-throughput biological data. This allows biologists to verify disease relevance in a biological experiment and identify unexpected disease associations. Comparison among gene clusters is also supported. AVAILABILITY AND IMPLEMENTATION: DOSE is released under Artistic-2.0 License. The source code and documents are freely available through Bioconductor (http://www.bioconductor.org/packages/release/bioc/html/DOSE.html). SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online. CONTACT: gcyu@connect.hku.hk or tqyhe@jnu.edu.cn.

First-Principles Study of Mo Segregation in MoNi(111): Effects of Chemisorbed Atomic Oxygen.

Segregation at metal alloy surfaces is an important issue because many electrochemical and catalytic properties are directly correlated to the surface composition. We have performed density functional theory calculations for Mo segregation in MoNi(111) in the presence of chemisorbed atomic oxygen. In particular, the coverage dependence and possible adsorption-induced segregation phenomena are addressed by investigating segregation energies of the Mo atom in MoNi(111). The theoretical calculated results show that the Mo atom prefers to be embedded in the bulk for the clean MoNi(111), while it segregates to the top-most layer when the oxygen coverage is thicker than 1/9 monolayer (ML). Furthermore, we analyze the densities of states for the clean and oxygen-chemisorbed MoNi(111), and see a strong covalent bonding between Mo d-band states and O p-states. The present study provides valuable insight for exploring practical applications of Ni-based alloys as hydrogen evolution electrodes.