bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of multi‐walled carbon nanotubes addition on the interfacial property of titanium‐based fiber metal laminates
Authors: Zhang Xian , Hu Yubing , Li Huaguan , Tian Jingming , Fu Xuelong , Xu Yingmei , Lu Yi , Chen Yujie , Qin Liang , Tao Jie
Published: December 2017

Multi‐walled carbon nanotubes (MWCNTs) were introduced to improve the interfacial properties of titanium‐based fiber metal laminates, and the corresponding reinforcement mechanism and failure behavior were revealed. Diverse weight fractions (0, 2.5, 5, 7.5 wt%) of MWCNTs were dispersed in polymerized monomer reactant (PMR) polyimide adhesives by ultrasonic dispersion. Single lap shear tests of samples were conducted and average shear strengths were experimentally measured to characterize the interface bonding strengths between the titanium and polyimide. The shear strength of this polyimide adhesive was further enhanced by incorporating MWCNTs, with over 87.5% improvement for the MWCNTs toughened adhesive joints with concentration up to 5 wt%. Meanwhile, the influence of MWCNTs on the interlaminar shear strength (ILSS) of the Ti/Cf‐PMR polyimide was investigated through short‐beam three‐point‐bending tests. It was found that MWCNT incorporation into the polyimide significantly enhanced the ILSS by 39.4%. Furthermore, scanning electron microscopy (SEM) was used to investigate the interface morphology, and the results of SEM images revealed MWCNTs failure morphologies, such as pull‐out, fracture, and bridging. The above results indicated the contribution of MWCNTs to the improvement of shear strength in these fiber metal laminates. POLYM. COMPOS., 39:E1159–E1168, 2018. © 2017 Society of Plastics Engineers
Improvement of the water repellency, dimensional stability, and biological resistance of bamboo‐based fiber reinforced composites
Authors: Meng Fandan , Liu Ru , Zhang Yahui , Huang Yuxiang , Yu Yanglun , Yu Wenji
Published: December 2017

In this study, a novel composite was fabricated based on phenol‐formaldehyde (PF) resin and bamboo fiber bundles. Various characterization techniques including fluorescence microscope, scanning electron microscopy coupled with energy‐dispersive X‐ray, and transmission electron microscope were used to investigate the distribution of fibers and infiltration of PF resin. The water repellency, dimensional stability, and decay resistance against both white‐rot (Trametes versicolor) and brown‐rot (Gloeophyllum trabeum) of the composites were also tested. The results showed that the resin not only deposited on the fibers surface, but also entered into the cellular wall and cell lumina through the pits. A great amount of resin was found in cracks and middle lamella of cell wall in resin impregnated bamboo fiber bundles owing to the mechanical defibering process. After thermal compressing, the bamboo cells were densified. The resin was redistributed in cell lumen and glue‐joints were formed. Some chemical reactions occurred between PF and bamboo by formation of aromatic esters and ether bonds, and the ether bonds were dominant. Thus, significant improvements in water repellency, dimensional stability, and biological resistance were achieved. These results suggested the composites can be used in exterior applications where high levels of water repellency and fungi resistance were required. POLYM. COMPOS., 40:506–513, 2019. © 2017 Society of Plastics Engineers
Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics
Authors: Wlodarski P. G. , Pittman J. F. T.
Published: December 2017

We study injection molding of mesoscale items with µm‐scale surface features, namely micro‐fluidic channels, relating replication quality to process conditions. Using variothermal molding, the variables are the pre‐heat temperature of the cavity insert surface before melt injection and the mold cooling start time. Surface temperatures and in‐cavity melt pressures are continuously measured. Rounded upper corners of the micro‐channels are used as an index of replication quality. For polymethylmethacrylate the thickness of a layer with solid‐like properties (below 124°C) is calculated and used with pressures to interpret results. It is shown how improved replication correlates with low layer thickness at the end of the compression phase when pressures are at a maximum, and the necessity of properly timed cooling to lock in replication before melt pressures fall. Results show how the inter‐relationship of layer thickness and melt pressure is controlled by pre‐heat temperature and cooling switch‐on time. Delayed cooling can result in poorer replication, due to a retraction effect of the plastic. Too early cooling also reduces replication of parallel‐to‐flow features downstream of transverse features, and of the replication of transverse features on their downstream side. Good replication of 100 and 70 µm channels requires lower pre‐heat than 400 µm ones. POLYM. ENG. SCI., 58:1726–1738, 2018. © 2017 Society of Plastics Engineers
Theoretical study of the furfuryl benzoate and furfuryl acetate pyrolysis
Authors: Mora Jose R. , Rincón Luis , Javier Torres F. , Zambrano Cesar H. , Muñoz Carlos
Published: December 2017

In the present work, the pyrolysis reaction mechanism of both furfuryl benzoate and furfuryl acetate was evaluated at the M06/6‐311++g(d,p) level. The uncommon methylenecyclobutenone compound and either the benzoic or the acetic acid were determined as the products of a multistep process consisting in two [3 + 3] rearrangements and a subsequent hydrogen α‐elimination step, through a cyclic 5‐membered transition state (TS), being the latter the rate‐limiting step for both reactants. Furthermore, a deeper analysis on the basis of the reaction force formalism showed that the TS is formed in two stages: The first one is characterized by the weakening of the C─O bond, and the second one is where the H atom is transferred from the C atom to its nearest O atom. The H─O bond formation was determined to contribute the most to the electronic activity occurring during the TS formation as suggested by a reaction electronic flux analysis. Accordingly, natural bond orbital calculations showed that the most significant changes occur in the charge distribution of the O and H atoms. Finally, a negligible effect of the substituting group on the reaction was determined since similar activation energies were obtained for the pyrolysis of furfuryl benzoate and furfuryl acetate; however, a minor difference was evidenced in the reaction force results. In this sense, the structural contribution to the activation energy is larger than the electronic one for the furfuryl benzoate reaction,
, whereas the opposite is observed for the furfuryl acetate reaction,
.
Diphenylphenacyl sulfonium salt as dual photoinitiator for free radical and cationic polymerizations
Authors: Kaya Kerem , Kreutzer Johannes , Yagci Yusuf
Published: December 2017

Diphenylphenacylsulfonium tetrafluoroborate (DPPS+BF4–) salt possessing both phenacyl and sulfonium structural units was synthesized and characterized. DPPS+BF4– absorbs light at relatively higher wavelengths. The direct and sensitized initiation activity of the salt in both cationic and free radical photopolymerizations was investigated and compared with that of its analogue triphenylsulfonium tetrafluoroborate (TPS+BF4–). Differential scanning photocalorimetry and conventional gravimetric studies revealed that DPPS+BF4– showed higher efficiency for direct and sensitized photopolymerizations of most of the monomers investigated. Although, principally both homolytic and/or heterolytic cleavage is possible, theoretical studies suggested that homolytic pathway is more favored for the generation of reactive initiating species. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 451–457
Apparent depth‐dependent modulus and hardness of polymers by nanoindentation: Investigation of surface detection error and pressure effects
Authors: Qian Zhiyuan , Risan Jared , Stadnick Benjamin , McKenna Gregory B.
Published: December 2017

Nanoindentation is a widely used technique to characterize the mechanical properties of polymeric materials at the nanoscale. Extreme surface stiffening has been reported for soft polymers such as poly(dimethylsiloxane) (PDMS) rubber. Our recent work [J. Polym. Sci. Part B Polym. Phys.2017,55, 30–38] provided a quantitative model which demonstrates such extreme stiffening can be associated with experimental artifacts, for example, error in surface detection. In this work, we have further investigated the effect of surface detection error on the determination of mechanical properties by varying the sample modulus, instrument surface detection criterion, and probe geometry. We have examined materials having Young's moduli from ∼2 MPa (PDMS) to 3 GPa (polystyrene) using two different nanoindentation instruments (G200 and TI 950) which implement different surface detection methods. The results show that surface detection error can lead to apparent large stiffening. The errors are lower for the stiffer materials, but can still be significant if care is not taken to establish the range of the surface detection error in a particular experimental situation. We have also examined the effect of pressure beneath the probe on the nanoindentation‐determined modulus of polystyrene with different probe geometries. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2018,56, 414–428
Evaluation of the Deuterium Isotope Effect in the Detonation of Aluminum Containing Explosives
Authors: Tappan Bryce C. , Bowden Patrick R. , Manner Virginia W. , Leiding Jeffery A. , Jakulewicz Micah S.
Published: December 2017

During or shortly after a detonation in condensed explosives, the reaction rates and the physical mechanism controlling aluminum reaction is poorly understood. We utilize the kinetic isotope effect to probe Al reactions in detonation product gases in aluminized, protonated and deuterated high explosives using high‐fidelity detonation velocity and cylinder wall expansion velocity measurements. By observation of the profile of cylinder wall velocity versus time, we are able to determine the timing of aluminum contribution to energy release in product gases and observe the presence or absence of rate changes isotopic substitution. By comparison of the Al oxidation with lithium fluoride (LiF), data indicate that Al oxidation occurs on an extremely fast time scale, with post‐detonation kinetic isotope effects observed in carbon containing formulations.
Watt‐Class Green (530 nm) and Blue (465 nm) Laser Diodes
Authors: Murayama Masahiro , Nakayama Yusuke , Yamazaki Kenji , Hoshina Yukio , Watanabe Hideki , Fuutagawa Noriyuki , Kawanishi Hidekazu , Uemura Toshiya , Narui Hironobu
Published: December 2017

In this research, watt‐class green and blue laser diodes, which are fabricated on free‐standing semipolar GaN and conventional c‐plane GaN substrates, respectively are developed. Although several research groups have recently developed green laser diodes on semipolar GaN substrates, which have weaker piezoelectric fields and higher indium homogeneity in InGaN active regions compared to c‐plane GaN, watt‐level output power has yet to be achieved. By utilizing the plane, the first watt‐class green lasers at 530 nm is successfully fabricated, and achieve maximum output powers in excess of 2 W, which to the best of our knowledge is the highest value reported for any GaN‐based green laser diode. A wall‐plug efficiency of 17.5% is realized at a current of 1.2 A under continuous‐wave operation, which corresponds to an optical output of approximately 1 W and is the highest value reported to date. In addition, high‐power and high‐efficiency blue laser diodes at 465 nm are successfully fabricated on conventional c‐plane GaN substrates. The output power and wall‐plug efficiency are 5.2 W and 37.0%, respectively, at a current of 3.0 A under continuous‐wave operation. These laser diodes are promising light sources meeting the ITU‐R Recommendation BT.2020 for future laser display applications.
Dye Aggregates in Luminescent Solar Concentrators
Authors: Eisfeld Alexander , Briggs John S.
Published: December 2017

In this paper the design of a luminescent solar concentrator (LSC) in which dye aggregates with cylindrical geometry are embedded in the LSC plate with the long cylinder axis orthogonal to the faces of the plate is proposed. The most suitable aggregates are those exhibiting a blue‐shifted (with respect to monomer absorption) H band and a narrow red‐shifted J band. Such aggregates have high primary absorption into the H band which is polarized in the plane of the LSC and emission from the J band which is polarized perpendicular to the plane. Hence the emitted light is directed predominantly to the edges of the LSC and loss into the escape zone is much reduced.
Luminescence Properties of ZnO Twin Nanorod–Ag Heteronanocrystals and Interfacial Exciton–Surface Plasmon Coupling
Authors: Fan Baolu , Zhang Yumeng , Gu Chao , Wang Weizheng , Fan Jiyang
Published: December 2017

The epitaxial semiconductor–metal interface has unique optical properties. However, people know little about the coupling modes at the semiconductor–metal interface of heteronanocrystals both experimentally and theoretically. The coupling between the semiconductor excitons and the metal surface plasmons in the ZnO twin nanorod–Ag heteronanocrystals is studied. These heteronanocrystals are synthesized through photoreduction of silver ions on the ZnO twin‐nanorods. The interfacial epitaxial relation of the perfect heteronanocrystals is found to be (0001)ZnO//(111)Ag. The hybrid exciton energy splitting of 97 meV is observed from the absorption spectrum. The photoluminescence of the hybrid excitons shifts to red significantly relative to that of the uncoupled excitons. The theoretical model concerning the exciton–surface plasmon coupling is proposed to account for the experimental phenomena.
Tracing the source of methomyl using stable isotope analysis
Authors: Song Byeong‐Yeol , Gwak Seongshin , Jung Minji , Nam Geummun , Kim Nam Yee
Published: December 2017

Rationale

Pesticide self‐poisoning is a major method of suicide in many agricultural communities worldwide. In addition, there are a number of known crime cases related to people being harmed by insecticides. Methomyl, a prohibited insecticide in the Republic of Korea, has high toxicity and is frequently used for self‐poisoning. In this study, we investigated the source of origin of methamyl in a fatal poisoning case using stable isotope ratio analysis.

Methods

Two bottles of Soju from a crime scene were seized and nine different brands of methomyl products were collected from the neighborhood for analysis. In addition, the gastric contents and energy drink from the person who had committed suicide were analyzed. Isotope analysis using GC/Isolink/IRMS was conducted to determine the source of the methomyl by comparing their carbon and nitrogen isotope ratios. Linear discriminant analysis was utilized to verify the results.

Results

Isotope ratio analysis showed that the isotope ratio ranges of methomyl found in the Soju, the gastric contents of the suicide victim, and the energy drink bottle were similar to those of a seized methomyl product, Samgong methomyl 2011 (SG11). Thus, it was assumed that SG11 was used in this fatal poisoning case.

Conclusions

This study demonstrates the potential of stable isotope ratio analysis for the determination of insecticide origin in fatal poisoning cases.
Highly dexterous 2‐module soft robot for intra‐organ navigation in minimally invasive surgery
Authors: Abidi Haider , Gerboni Giada , Brancadoro Margherita , Fras Jan , Diodato Alessandro , Cianchetti Matteo , Wurdemann Helge , Althoefer Kaspar , Menciassi Arianna
Published: December 2017

Background

For some surgical interventions, like the Total Mesorectal Excision (TME), traditional laparoscopes lack the flexibility to safely maneuver and reach difficult surgical targets. This paper answers this need through designing, fabricating and modelling a highly dexterous 2‐module soft robot for minimally invasive surgery (MIS).

Methods

A soft robotic approach is proposed that uses flexible fluidic actuators (FFAs) allowing highly dexterous and inherently safe navigation. Dexterity is provided by an optimized design of fluid chambers within the robot modules. Safe physical interaction is ensured by fabricating the entire structure by soft and compliant elastomers, resulting in a squeezable 2‐module robot. An inner free lumen/chamber along the central axis serves as a guide of flexible endoscopic tools. A constant curvature based inverse kinematics model is also proposed, providing insight into the robot capabilities.

Results

Experimental tests in a surgical scenario using a cadaver model are reported, demonstrating the robot advantages over standard systems in a realistic MIS environment.

Conclusion

Simulations and experiments show the efficacy of the proposed soft robot.
A weighted combined effect measure for the analysis of a composite time‐to‐first‐event endpoint with components of different clinical relevance
Authors: Rauch Geraldine , Kunzmann Kevin , Kieser Meinhard , Wegscheider Karl , König Jochem , Eulenburg Christine
Published: December 2017

Composite endpoints combine several events within a single variable, which increases the number of expected events and is thereby meant to increase the power. However, the interpretation of results can be difficult as the observed effect for the composite does not necessarily reflect the effects for the components, which may be of different magnitude or even point in adverse directions. Moreover, in clinical applications, the event types are often of different clinical relevance, which also complicates the interpretation of the composite effect. The common effect measure for composite endpoints is the all‐cause hazard ratio, which gives equal weight to all events irrespective of their type and clinical relevance. Thereby, the all‐cause hazard within each group is given by the sum of the cause‐specific hazards corresponding to the individual components. A natural extension of the standard all‐cause hazard ratio can be defined by a “weighted all‐cause hazard ratio” where the individual hazards for each component are multiplied with predefined relevance weighting factors. For the special case of equal weights across the components, the weighted all‐cause hazard ratio then corresponds to the standard all‐cause hazard ratio. To identify the cause‐specific hazard of the individual components, any parametric survival model might be applied. The new weighted effect measure can be tested for deviations from the null hypothesis by means of a permutation test. In this work, we systematically compare the new weighted approach to the standard all‐cause hazard ratio by theoretical considerations, Monte‐Carlo simulations, and by means of a real clinical trial example.
Bayesian inference for unidirectional misclassification of a binary response trait
Authors: Xia Michelle , Gustafson Paul
Published: December 2017

When assessing association between a binary trait and some covariates, the binary response may be subject to unidirectional misclassification. Unidirectional misclassification can occur when revealing a particular level of the trait is associated with a type of cost, such as a social desirability or financial cost. The feasibility of addressing misclassification is commonly obscured by model identification issues. The current paper attempts to study the efficacy of inference when the binary response variable is subject to unidirectional misclassification. From a theoretical perspective, we demonstrate that the key model parameters possess identifiability, except for the case with a single binary covariate. From a practical standpoint, the logistic model with quantitative covariates can be weakly identified, in the sense that the Fisher information matrix may be near singular. This can make learning some parameters difficult under certain parameter settings, even with quite large samples. In other cases, the stronger identification enables the model to provide more effective adjustment for unidirectional misclassification. An extension to the Poisson approximation of the binomial model reveals the identifiability of the Poisson and zero‐inflated Poisson models. For fully identified models, the proposed method adjusts for misclassification based on learning from data. For binary models where there is difficulty in identification, the method is useful for sensitivity analyses on the potential impact from unidirectional misclassification.
Induced smoothing for rank‐based regression with recurrent gap time data
Authors: Lyu Tianmeng , Luo Xianghua , Xu Gongjun , Huang Chiung‐Yu
Published: December 2017

Various semiparametric regression models have recently been proposed for the analysis of gap times between consecutive recurrent events. Among them, the semiparametric accelerated failure time (AFT) model is especially appealing owing to its direct interpretation of covariate effects on the gap times. In general, estimation of the semiparametric AFT model is challenging because the rank‐based estimating function is a nonsmooth step function. As a result, solutions to the estimating equations do not necessarily exist. Moreover, the popular resampling‐based variance estimation for the AFT model requires solving rank‐based estimating equations repeatedly and hence can be computationally cumbersome and unstable. In this paper, we extend the induced smoothing approach to the AFT model for recurrent gap time data. Our proposed smooth estimating function permits the application of standard numerical methods for both the regression coefficients estimation and the standard error estimation. Large‐sample properties and an asymptotic variance estimator are provided for the proposed method. Simulation studies show that the proposed method outperforms the existing nonsmooth rank‐based estimating function methods in both point estimation and variance estimation. The proposed method is applied to the data analysis of repeated hospitalizations for patients in the Danish Psychiatric Center Register.
Joint mixed‐effects models for causal inference with longitudinal data
Authors: Shardell Michelle , Ferrucci Luigi
Published: December 2017

Causal inference with observational longitudinal data and time‐varying exposures is complicated due to the potential for time‐dependent confounding and unmeasured confounding. Most causal inference methods that handle time‐dependent confounding rely on either the assumption of no unmeasured confounders or the availability of an unconfounded variable that is associated with the exposure (eg, an instrumental variable). Furthermore, when data are incomplete, validity of many methods often depends on the assumption of missing at random. We propose an approach that combines a parametric joint mixed‐effects model for the study outcome and the exposure with g‐computation to identify and estimate causal effects in the presence of time‐dependent confounding and unmeasured confounding. G‐computation can estimate participant‐specific or population‐average causal effects using parameters of the joint model. The joint model is a type of shared parameter model where the outcome and exposure‐selection models share common random effect(s). We also extend the joint model to handle missing data and truncation by death when missingness is possibly not at random. We evaluate the performance of the proposed method using simulation studies and compare the method to both linear mixed‐ and fixed‐effects models combined with g‐computation as well as to targeted maximum likelihood estimation. We apply the method to an epidemiologic study of vitamin D and depressive symptoms in older adults and include code using SAS PROC NLMIXED software to enhance the accessibility of the method to applied researchers.
Multivariate space‐time modelling of multiple air pollutants and their health effects accounting for exposure uncertainty
Authors: Huang Guowen , Lee Duncan , Scott E. Marian
Published: December 2017

The long‐term health effects of air pollution are often estimated using a spatio‐temporal ecological areal unit study, but this design leads to the following statistical challenges: (1) how to estimate spatially representative pollution concentrations for each areal unit; (2) how to allow for the uncertainty in these estimated concentrations when estimating their health effects; and (3) how to simultaneously estimate the joint effects of multiple correlated pollutants. This article proposes a novel 2‐stage Bayesian hierarchical model for addressing these 3 challenges, with inference based on Markov chain Monte Carlo simulation. The first stage is a multivariate spatio‐temporal fusion model for predicting areal level average concentrations of multiple pollutants from both monitored and modelled pollution data. The second stage is a spatio‐temporal model for estimating the health impact of multiple correlated pollutants simultaneously, which accounts for the uncertainty in the estimated pollution concentrations. The novel methodology is motivated by a new study of the impact of both particulate matter and nitrogen dioxide concentrations on respiratory hospital admissions in Scotland between 2007 and 2011, and the results suggest that both pollutants exhibit substantial and independent health effects.
Electron Holographic Study of Semiconductor Light‐Emitting Diodes
Authors: Li Luying , Hu Xiaokang , Gao Yihua
Published: December 2017

Semiconductor light‐emitting diodes (LEDs), especially GaN‐based heterostructures, are widely used in light illumination. The lack of inversion symmetry of wurtzite crystal structures and the lattice mismatch at heterointerfaces cause large polarization fields with contributions from both spontaneous polarization and piezoelectric polarization, which in turn results in obvious quantum confined stark effect. It is possible to alleviate this effect if the local electrostatic fields and band alignment induced charge redistribution can be quantitatively determined across the heterostructures. In this Concept, the applications of electron holography to investigate semiconductor LEDs are summarized. Following the off‐axis electron holography scheme, the GaN‐based LED heterostructures including InGaN/GaN‐based quantum wells, other GaN‐based quantum wells, and other forms of GaN‐based LED materials are discussed, focusing on the local potential drops, polarization fields, and charge distributions. Moreover, GaAs‐based LED heterostructures are briefly discussed. The in‐line electron holography scheme emphasizes the capability of large area strain mapping across LED heterostructures with high spatial resolution and accuracy, which is combined with quantitative electrostatic measurements and other advanced transmission electron microscopy characterizations to provide an overall nanometer scale perspective of LED devices for further improvement in their electric and optical properties.
Self‐Assembled Aptamer‐Nanomedicine for Targeted Chemotherapy and Gene Therapy
Authors: Zhao Nianxi , Zeng Zihua , Zu Youli
Published: December 2017

Chemotherapy is the mainstream treatment of anaplastic large cell lymphoma (ALCL). However, chemotherapy can cause severe adverse effects in patients because it is not ALCL‐specific. In this study, a multifunctional aptamer‐nanomedicine (Apt‐NMed) achieving targeted chemotherapy and gene therapy of ALCL is developed. Apt‐NMed is formulated by self‐assembly of synthetic oligonucleotides containing CD30‐specific aptamer and anaplastic lymphoma kinase (ALK)‐specific siRNA followed by self‐loading of the chemotherapeutic drug doxorubicin (DOX). Apt‐NMed exhibits a well‐defined nanostructure (diameter 59 mm) and stability in human serum. Under aptamer guidance, Apt‐NMed specifically binds and internalizes targeted ALCL cells. Intracellular delivery of Apt‐NMed triggers rapid DOX release for targeted ALCL chemotherapy and intracellular delivery of the ALK‐specific siRNA induced ALK oncogene silencing, resulting in combined therapeutic effects. Animal model studies reveal that upon systemic administration, Apt‐NMed specifically targets and selectively accumulates in ALCL tumor site, but does not react with off‐target tumors in the same xenograft mouse. Importantly, Apt‐NMed not only induces significantly higher inhibition in ALCL tumor growth, but also causes fewer or no side effects in treated mice compared to free DOX. Moreover, Apt‐NMed treatment markedly improves the survival rate of treated mice, opening a new avenue for precision treatment of ALCL.
Ultrathin Nanosheet Assembled Sn0.91Co0.19S2 Nanocages with Exposed (100) Facets for High‐Performance Lithium‐Ion Batteries
Authors: Li Bing , Gu Peng , Zhang Guangxun , Lu Yao , Huang Kesheng , Xue Huaiguo , Pang Huan
Published: December 2017

Ultrathin 2D inorganic nanomaterials are good candidates for lithium‐ion batteries, as well as the micro/nanocage structures with unique and tunable morphologies. Meanwhile, as a cost‐effective method, chemical doping plays a vital role in manipulating physical and chemical properties of metal oxides and sulfides. Thus, the design of ultrathin, hollow, and chemical doped metal sulfides shows great promise for the application of Li‐ion batteries by shortening the diffusion pathway of Li ions as well as minimizing the electrode volume change. Herein, ultrathin nanosheet assembled Sn0.91Co0.19S2 nanocages with exposed (100) facets are first synthesized. The as‐prepared electrode delivers an excellent discharge capacity of 809 mA h g−1 at a current density of 100 mA g−1 with a 91% retention after 60 discharge–charge cycles. The electrochemical performance reveals that the Li‐ion batteries prepared by Sn0.91Co0.19S2 nanocages have high capacity and great cycling stability.
Interface Engineering with MoS2–Pd Nanoparticles Hybrid Structure for a Low Voltage Resistive Switching Memory
Authors: Wang Xue‐Feng , Tian He , Zhao Hai‐Ming , Zhang Tian‐Yu , Mao Wei‐Quan , Qiao Yan‐Cong , Pang Yu , Li Yu‐Xing , Yang Yi , Ren Tian‐Ling
Published: December 2017

Metal oxide‐based resistive random access memory (RRAM) has attracted a lot of attention for its scalability, temperature robustness, and potential to achieve machine learning. However, a thick oxide layer results in relatively high program voltage while a thin one causes large leakage current and a small window. Owing to these fundamental limitations, by optimizing the oxide layer itself a novel interface engineering idea is proposed to reduce the programming voltage, increase the uniformity and on/off ratio. According to this idea, a molybdenum disulfide (MoS2)–palladium nanoparticles hybrid structure is used to engineer the oxide/electrode interface of hafnium oxide (HfOx)‐based RRAM. Through its interface engineering, the set voltage can be greatly lowered (from −3.5 to −0.8 V) with better uniformity under a relatively thick HfOx layer (≈15 nm), and a 30 times improvement of the memory window can be obtained. Moreover, due to the atomic thickness of MoS2 film and high transmittance of ITO, the proposed RRAM exhibits high transparency in visible light. As the proposed interface‐engineering RRAM exhibits good transparency, low SET voltage, and a large resistive switching window, it has huge potential in data storage in transparent circuits and wearable electronics with relatively low supply voltage.
Encapsulation of Gold Nanoparticles into DNA Minimal Cages for 3D‐Anisotropic Functionalization and Assembly
Authors: Luo Xin , Chidchob Pongphak , Rahbani Janane F. , Sleiman Hanadi F.
Published: December 2017

Gold nanoparticles (AuNPs) endowed with anisotropic DNA valency are an important class of materials, as they can assemble into complex structures with a minimal number of DNA strands. However, methods to encode 3D DNA strand patterns on AuNPs with a controlled number of unique DNA strands in a predesigned spatial arrangement remain elusive. In this work, a simple one‐step method to yield such DNA‐decorated AuNPs is demonstrated, through encapsulating AuNPs into DNA minimal nanocages. The AuNP@DNA cage encapsulation complex inherits the 3D anisotropic molecular information from the DNA nanocage with enhanced structural stability. The DNA nanocage can be further functionalized and used as a building block for the self‐assembly of complex architectures, such as dimers and trimers, programmed assemblies with sequential growth DNA backbones and DNA origami.
Nanomotion Detection Method for Testing Antibiotic Resistance and Susceptibility of Slow‐Growing Bacteria
Authors: Villalba María Ines , Stupar Petar , Chomicki Wojciech , Bertacchi Massimiliano , Dietler Giovanni , Arnal Laura , Vela María Elena , Yantorno Osvaldo , Kasas Sandor
Published: December 2017

Infectious diseases are caused by pathogenic microorganisms and are often severe. Time to fully characterize an infectious agent after sampling and to find the right antibiotic and dose are important factors in the overall success of a patient's treatment. Previous results suggest that a nanomotion detection method could be a convenient tool for reducing antibiotic sensitivity characterization time to several hours. Here, the application of the method for slow‐growing bacteria is demonstrated, taking Bordetella pertussis strains as a model. A low‐cost nanomotion device is able to characterize B. pertussis sensitivity against specific antibiotics within several hours, instead of days, as it is still the case with conventional growth‐based techniques. It can discriminate between resistant and susceptible B. pertussis strains, based on the changes of the sensor's signal before and after the antibiotic addition. Furthermore, minimum inhibitory and bactericidal concentrations of clinically applied antibiotics are compared using both techniques and the suggested similarity is discussed.
A Monodispersed Spherical Zr‐Based Metal–Organic Framework Catalyst, Pt/Au@Pd@UIO‐66, Comprising an Au@Pd Core–Shell Encapsulated in a UIO‐66 Center and Its Highly Selective CO2 Hydrogenation to Produce CO
Authors: Zheng Zhizhong , Xu Haitao , Xu Zhenliang , Ge Jianping
Published: December 2017

A Zr‐based metal–organic framework (MOF) catalyst, Pt/Au@Pd@UIO‐66, is assembled, where UIO‐66 is Zr6O4(OH)4(BDC)6 (BDC = 1,4‐benzenedicarboxylate). The gold nanoparticles (NPs) act as the core for the epitaxial growth of Pd shells, and the core–shell monodispersed nanosphere Au@Pd is encapsulated into UIO‐66 to control its morphology and impart nanoparticle functionality. The microporous nature of UIO‐66 assists the adsorption of Pt NPs, which in turn enhances the interaction between NPs and UIO‐66, favoring the formation of isolated and well‐dispersed Pt NP active sites. This MOF exhibits high catalytic activity and CO product selectivity for the reverse‐water–gas‐shift reaction in a fixed‐bed flow reactor.
Multistage Targeting Strategy Using Magnetic Composite Nanoparticles for Synergism of Photothermal Therapy and Chemotherapy
Authors: Wang Yi , Wei Guoqing , Zhang Xiaobin , Huang Xuehui , Zhao Jingya , Guo Xing , Zhou Shaobing
Published: December 2017

Mitochondrial‐targeting therapy is an emerging strategy for enhanced cancer treatment. In the present study, a multistage targeting strategy using doxorubicin‐loaded magnetic composite nanoparticles is developed for enhanced efficacy of photothermal and chemical therapy. The nanoparticles with a core–shell–SS–shell architecture are composed of a core of Fe3O4 colloidal nanocrystal clusters, an inner shell of polydopamine (PDA) functionalized with triphenylphosphonium (TPP), and an outer shell of methoxy poly(ethylene glycol) linked to the PDA by disulfide bonds. The magnetic core can increase the accumulation of nanoparticles at the tumor site for the first stage of tumor tissue targeting. After the nanoparticles enter the tumor cells, the second stage of mitochondrial targeting is realized as the mPEG shell is detached from the nanoparticles by redox responsiveness to expose the TPP. Using near‐infrared light irradiation at the tumor site, a photothermal effect is generated from the PDA photosensitizer, leading to a dramatic decrease in mitochondrial membrane potential. Simultaneously, the loaded doxorubicin can rapidly enter the mitochondria and subsequently damage the mitochondrial DNA, resulting in cell apoptosis. Thus, the synergism of photothermal therapy and chemotherapy targeting the mitochondria significantly enhances the cancer treatment.
In Situ Synthesis of Few‐Layered g‐C3N4 with Vertically Aligned MoS2 Loading for Boosting Solar‐to‐Hydrogen Generation
Authors: Bian Hui , Ji Yujin , Yan Junqing , Li Ping , Li Ling , Li Youyong , (Frank) Liu Shengzhong
Published: December 2017

In artificial photocatalytic hydrogen evolution, effective incident photon absorption and a high‐charge recombination rate are crucial factors influencing the overall efficiency. Herein, a traditional solid‐state synthesis is used to obtain, for the first time, novel samples of few‐layered g‐C3N4 with vertically aligned MoS2 loading (MoS2/C3N4). Thiourea and layered MoO3 are chosen as precursors, as they react under nitrogen atmosphere to in situ produce the products. According to the quasi‐Fourier transform infrared reflectance and X‐ray diffraction measurements, the detailed reaction process is determined to proceed through the confirmed formation pathway. The two precursor units MoS2 and C3N4 are linked by MoN bonds, which act as electronic receivers/conductors and hydrogen‐generation sites. Density functional theory is also carried out, which determines that the interface sites act as electron‐accumulation regions. According to the photoelectrochemical results, MoS2/C3N4 can achieve a current of 0.05 mA cm−2, which is almost ten times higher than that of bare g‐C3N4 or the MoS2/C3N4‐R reference samples. The findings in the present work pave the way to not only synthesize a series of designated samples but also thoroughly understand the solid‐state reaction.
Glycyrrhetinic Acid Functionalized Graphene Oxide for Mitochondria Targeting and Cancer Treatment In Vivo
Authors: Zhang Chao , Liu Zunfeng , Zheng Ying , Geng Yadi , Han Chao , Shi Yamin , Sun Hongbin , Zhang Can , Chen Yijun , Zhang Luyong , Guo Qinglong , Yang Lei , Zhou Xiang , Kong Lingyi
Published: December 2017

Mitochondria‐mediated apoptosis (MMA) is a preferential option for cancer therapy due to the presence of cell‐suicide factors in mitochondria, however, low permeability of mitochondria is a bottleneck for targeting drug delivery. In this paper, glycyrrhetinic acid (GA), a natural product from Glycyrrhiza glabra, is found to be a novel mitochondria targeting ligand, which can improve mitochondrial permeability and enhance the drug uptake of mitochondria. GA‐functionalized graphene oxide (GO) is prepared and used as an effective carrier for targeted delivery of doxorubicin into mitochondria. The detailed in vitro and in vivo mechanism study shows that GA‐functionalized GO causes a decrease in mitochondrial membrane potential and activates the MMA pathway. The GA‐functionalized drug delivery system demonstrates highly improved apoptosis induction ability and anticancer efficacy compared to the non‐GA‐functionalized nanocarrier delivery system. The GA‐functionalized nanocarrier also shows low toxicity, suggesting that it can be a useful tool for drug delivery.
Corruption and Entrepreneurship: Cross‐Country Evidence from Formal and Informal Sectors
Authors: Berdiev Aziz N. , Saunoris James W.
Published: December 2017

While the impact of institutional quality on formal entrepreneurial activity has been well documented in the literature, whether and to what extent corruption influences entrepreneurship in the informal sector is less forthcoming. In this article, we analyze the effect of corruption on entrepreneurship in the formal and informal sectors. Using unique cross‐country data on formal and informal entrepreneurship, we find that corruption deters entrepreneurship in the formal sector and promotes informal entrepreneurship. These results remain robust even after conducting a series of sensitivity analyses.
Monitoring of structural modal parameters and dynamic responses of a 600m‐high skyscraper during a typhoon
Authors: He Yinghou , Li Qiusheng , Zhu Hongping , Han Xuliang , He Yuncheng , Li Xiao
Published: December 2017

This paper presents field measurement results of structural dynamic properties and wind‐induced responses of 600m‐high Ping‐An Finance Center in Shenzhen during the passage of Typhoon Haima. The field measurements included wind speed, wind direction, and structural acceleration responses during the typhoon. Analysis of the field measurements is carried out to investigate the wind‐induced structural vibrations and dynamic properties of the skyscraper under typhoon condition. In the analysis, natural frequencies and damping ratios of Ping‐An Finance Center are estimated using Peak‐Picking method, half‐power bandwidth method in frequency domain, and random decrement technique in time domain, respectively. Two band‐pass filtering methods, namely, elliptical filtering method and Kaiser‐window FIR filter, are adopted to deal with the measured acceleration signals. Consequently, the modal parameters identified with the Peak‐Picking, half‐power bandwidth, and random decrement technique methods are presented and discussed in detail. In addition, the probabilistic characteristics of the recorded acceleration responses are analyzed using the generalized extreme value distribution, and then the serviceability of the skyscraper during the typhoon is evaluated.
Brain angiogenic gene expression in fetuses with congenital heart disease
Authors: Sánchez O. , Ruiz‐Romero A. , Domínguez C. , Ferrer Q. , Ribera I. , Rodríguez‐Sureda V. , Alijotas J. , Arévalo S. , Carreras E. , Cabero L. , Llurba E.
Published: December 2017

Objective

To assess potential differences in the expression of antiangiogenic and angiogenic factors and of genes associated with chronic hypoxia in cerebral tissue of euploid fetuses with congenital heart disease (CHD) vs those without.

Methods

Cerebral tissue was obtained from 15 fetuses with CHD and 12 control fetuses that had undergone termination of pregnancy. Expression profiles of the antiangiogenic factor soluble fms‐like tyrosine kinase‐1 (sFlt‐1), the angiogenic vascular endothelial growth factor‐A (VEGF‐A) and placental growth factor (PlGF), and of genes associated with chronic hypoxia were determined by real‐time polymerase chain reaction in tissue from the frontal cortex and the basal ganglia of the fetuses.

Results

Expression of sFlt‐1 was 48% higher in the frontal cortex (P = 0.0431) and 72% higher in the basal ganglia (P = 0.0369) of CHD fetuses compared with controls. The expression of VEGF‐A was 60% higher (P = 0.0432) and that of hypoxia‐inducible factor 2‐alpha was 98% higher (P = 0.0456) in the basal ganglia of CHD fetuses compared with controls. No significant differences were observed between the two groups in the expression of PlGF and hypoxia‐inducible factor 1‐alpha.

Conclusion

An overall dysregulation of angiogenesis with a net balance towards an antiangiogenic environment was observed in the cerebral tissue of fetuses with CHD, suggesting that these fetuses may have an intrinsic angiogenic impairment that could contribute to impaired brain perfusion and abnormal neurological development later in life. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.
In silicotoxicology: comprehensive benchmarking of multi‐label classification methods applied to chemical toxicity data
Authors: Raies Arwa B. , Bajic Vladimir B.
Published: December 2017

One goal of toxicity testing, among others, is identifying harmful effects of chemicals. Given the high demand for toxicity tests, it is necessary to conduct these tests for multiple toxicity endpoints for the same compound. Current computational toxicology methods aim at developing models mainly to predict a single toxicity endpoint. When chemicals cause several toxicity effects, one model is generated to predict toxicity for each endpoint, which can be labor and computationally intensive when the number of toxicity endpoints is large. Additionally, this approach does not take into consideration possible correlation between the endpoints. Therefore, there has been a recent shift in computational toxicity studies toward generating predictive models able to predict several toxicity endpoints by utilizing correlations between these endpoints. Applying such correlations jointly with compounds' features may improve model's performance and reduce the number of required models. This can be achieved through multi‐label classification methods. These methods have not undergone comprehensive benchmarking in the domain of predictive toxicology. Therefore, we performed extensive benchmarking and analysis of over 19,000 multi‐label classification models generated using combinations of the state‐of‐the‐art methods. The methods have been evaluated from different perspectives using various metrics to assess their effectiveness. We were able to illustrate variability in the performance of the methods under several conditions. This review will help researchers to select the most suitable method for the problem at hand and provide a baseline for evaluating new approaches. Based on this analysis, we provided recommendations for potential future directions in this area.

This article is categorized under:

Computer and Information Science > Chemoinformatics

Computer and Information Science > Computer Algorithms and Programming
Climate variability and changes in local climate
Authors: V Dani , Pal B. K.
Published: December 2017

Trend analysis is an ideal way of investigating first‐hand information about climate change; climate variables exhibit trends on variety of scales, and an understanding of these trends can be used to make estimates about the future of the climate. The objective of this paper is to examine temporal variations in climate by analysing climatic variables. Angul is one of the hottest districts in India, with a maximum summer temperature of 50°C recorded in 2005. Climate data for the period 1901 to 2015 have been statistically analysed to investigate variations in climate in the region. The nonparametric Mann–Kendall rank test, Pearson's correlation, Kendall's rank correlation, analysis of variance (ANOVA) and the autoregressive integrated moving average (ARIMA) model were used to identify diurnal, monthly, seasonal, and annual changes in temperature, precipitation, vapour pressure, potential evapotranspiration and crop evapotranspiration. The results of these analyses reveal the presence of both increasing and decreasing trends for a number of climate variables. Temperature has increased drastically over the last three decades. The average minimum and maximum temperatures for 1901 were 20 and 31°C, respectively; these values increased to 23 and 33°C in 2015. The Auto‐Regressive Integrated Moving Average model projected a significant rise in seasonal temperature and a decreasing trend in rainfall; these results are considered to be an early warning sign for future extreme climate events.
Wind and solar resource data sets
Authors: Clifton Andrew , Hodge Bri‐Mathias , Draxl Caroline , Badger Jake , Habte Aron
Published: December 2017

The range of resource data sets spans from static cartography showing the mean annual wind speed or solar irradiance across a region to high temporal and high spatial resolution products that provide detailed information at a potential wind or solar energy facility. These data sets are used to support continental‐scale, national, or regional renewable energy development; facilitate prospecting by developers; and enable grid integration studies. This review first provides an introduction to the wind and solar resource data sets, then provides an overview of the common methods used for their creation and validation. A brief history of wind and solar resource data sets is then presented, followed by areas for future research. WIREs Energy Environ 2018, 7:e276. doi: 10.1002/wene.276

This article is categorized under:

Wind Power > Climate and Environment

Solar Heating and Cooling > Climate and Environment

Energy Infrastructure > Climate and Environment