bluuebunny/crossref_metadata_2025 huggingface dataset:
Realizing Efficient Lead‐Free Formamidinium Tin Triiodide Perovskite Solar Cells via a Sequential Deposition Route
Authors: Zhu Zonglong , Chueh Chu‐Chen , Li Nan , Mao Chengyi , Jen Alex K.‐Y.
Published: December 2017

Recently, the evolved intermediate phase based on iodoplumbate anions that mediates perovskite crystallization has been embodied as the Lewis acid–base adduct formed by metal halides (serve as Lewis acid) and polar aprotic solvents (serve as Lewis base). Based on this principle, it is proposed to constitute efficient Lewis acid–base adduct in the SnI2 deposition step to modulate its volume expansion and fast reaction with methylammonium iodide (MAI)/formamidinium iodide (FAI) (FAI is studied hereafter). Herein, trimethylamine (TMA) is employed as the additional Lewis base in the tin halide solution to form SnY2–TMA complexes (Y = I−, F−) in the first‐step deposition, followed by intercalating with FAI to convert into FASnI. It is shown that TMA can facilitate homogeneous film formation of a SnI2 (+SnF2) layer by effectively forming intermediate SnY2–TMA complexes. Meanwhile, its relatively larger size and weaker affinity with SnI2 than FA+ ions will facilitate the intramolecular exchange with FA+ ions, thereby enabling the formation of dense and compact FASnI3 film with large crystalline domain (>1 µm). As a result, high power conversion efficiencies of 4.34% and 7.09% with decent stability are successfully accomplished in both conventional and inverted perovskite solar cells, respectively.
Filtration‐Assisted Fabrication of Large‐Area Uniform and Long‐Term Stable Graphene Isolated Nano‐Ag Array Membrane as Surface Enhanced Raman Scattering Substrate
Authors: Ouyang Lei , Wang Yesheng , Zhu Lihua , Irudayaraj Joseph , Tang Heqing
Published: December 2017

In this research, a facile strategy to obtain graphene isolated uniform Ag array membrane that are stable for long‐term use as surface enhanced Raman scattering (SERS) substrates is demonstrated. The fabrication process consisted of three main steps: interfacial assembly of Ag nanoparticles (NPs) into an array, transferring the Ag array to a membrane, and tightly wrapping the Ag array with graphene. The fabricated Ag array and graphene layer structure is tightly packed with effective electromagnetic coupling and electron transferring as confirmed by X‐ray photoelectron spectroscopy, UV‐vis spectra and Raman analysis. Owing to the uniform and effective electromagnetic coupling between Ag NPs and chemical enhancement from tightly wrapped graphene, this hierarchical membrane exhibited excellent SERS enhancing ability (an enhancement factor of 7.3 × 108) and large area uniformity (with relative standard deviation less than 5.91% for 50 times of detection over an area up to 9 cm2). Due to the protection effect by graphene as both an isolation layer and an electron shuttle, this substrate showed out‐standing long‐term stability (stable more than 25 weeks). Specific functions of graphene in fluorescence quenching and photo‐bleaching inhibition further contributed to intrinsic Raman information access. The obtained flexible membrane based multi‐layer architecture is also easy of use for real application.
Thermoelectric Devices: A Review of Devices, Architectures, and Contact Optimization
Authors: He Ran , Schierning Gabi , Nielsch Kornelius
Published: December 2017

In recent years, the substantially improved performance of thermoelectric (TE) materials has attracted considerable interest in studying the potential applications of the TE technique. Serving as the bridge between TE materials and applicable TE products, TE devices must be properly designed, engineered, and assembled to meet the required performance of TE products for cooling (thermoelectric cooler) and power generation (thermoelectric generator). The principle feasibility of the TE technique has been demonstrated using a variety of different materials and processing technologies, and many different architectures of TE devices have been successfully realized. This review discusses the architectures of TE devices, including bulk and thin‐film TE devices, TE devices with flexible designs, pn‐junction‐based TE devices that provide robust solutions for high operation temperatures, and the meta‐material‐based transverse TE devices. In addition, the assembly of TE devices involves contact layers on which the reliability of TE devices depends. Thus solutions to contact issues, including bonding strength, contact resistance, and thermomechanical stress, are also reviewed.
Fracture Behavior of Nanoscale Notched Silicon Beams Investigated by the Theory of Critical Distances
Authors: Gallo Pasquale , Yan Yabin , Sumigawa Takashi , Kitamura Takayuki
Published: December 2017

This paper investigates the nanoscale fracture behavior of silicon using the Theory of Critical Distances (TCD) and demonstrates that TCD can correctly estimate the magnitude of the breakdown of continuum fracture mechanics. Moreover, it proposes the TCD as an alternative strategy for the determination of fracture toughness, KIC, at the nanoscale. More specifically, in situ micromechanical testing of notched nano‐cantilever beams has been carried out in a transmission electron microscope. The material characteristic length and fracture toughness are then evaluated. The average KIC value obtained is 0.98 MPa m0.5, which is in agreement with that reported in the literature for macro‐Si. The characteristic length L is in the range of 1.3–1.9 nm. It is found that within an atomistic interpretation of the fracture of silicon, these values are in agreement with the breakdown of continuum fracture mechanics.
Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method
Authors: Jiang Kui , Zhang Guangye , Yang Guofang , Zhang Jianquan , Li Zhengke , Ma Tingxuan , Hu Huawei , Ma Wei , Ade Harald , Yan He
Published: December 2017

Ternary organic solar cells (OSCs) have attracted much research attention, as they can maintain the simplicity of the single‐junction device architecture while broadening the absorption range of OSCs. However, one main challenge that limits the development of ternary OSCs is the difficulty in controlling the morphology of ternary OSCs. In this paper, an effective approach to control the morphology is presented that leads to multiple cases of efficient nonfullerene ternary OSCs with efficiencies of up to 11.2%. This approach is based on a donor polymer with strong temperature dependent aggregation properties processed from hot solutions without any solvent additives and a pair of small molecular acceptors (SMAs) that have similar surface tensions and thus low propensity to form discrete phases. Such a ternary blend exhibits a simplified bulk‐heterojunction morphology that is similar to the morphology of previously reported binary blends. As a result, an almost linear relationship between VOC and film composition is observed for all nonfullerene ternary devices. Meanwhile, by carefully designing a control system with a large interfacial tension, a different phase separation and VOC dependence is demonstrated. This morphology control approach can be applicable to more material systems and accelerates the development of the ternary OSC field.
Facile Metal Coordination of Active Site Imprinted Nitrogen Doped Carbons for the Conservative Preparation of Non‐Noble Metal Oxygen Reduction Electrocatalysts
Authors: Mehmood Asad , Pampel Jonas , Ali Ghulam , Ha Heung Yong , Ruiz‐Zepeda Francisco , Fellinger Tim‐Patrick
Published: December 2017

Iron‐ or cobalt‐coordinated heteroatom doped carbons are promising alternatives for Pt‐based cathode catalysts in polymer‐electrolyte fuel cells. Currently, these catalysts are obtained at high temperatures. The reaction conditions complicate the selective and concentrated formation of metal–nitrogen active sites. Herein a mild procedure is introduced, which is conservative toward the carbon support and leads to active‐site formation at low temperatures in a wet‐chemical metal‐coordination step. Active‐site imprinted nitrogen doped carbons are synthesized via ionothermal carbonization employing Lewis‐acidic Mg2+ salt. The obtained carbons with large tubular porosity and imprinted N4 sites lead to very active catalysts with a half‐wave potential (E1/2) of up to 0.76 V versus RHE in acidic electrolyte after coordination with iron. The catalyst shows 4e− selectivity and exceptional stability with a half‐wave potential shift of only 5 mV after 1000 cycles. The X‐ray absorption fine structure as well as the X‐ray absorption near edge structure profiles of the most active catalyst closely match that of iron(II)phthalocyanine, proving the formation of active and stable FeN4 sites at 80 °C. Metal‐coordination with other transition metals reveals that Zn–Nx sites are inactive, while cobalt gives rise to a strong performance increase even at very low concentrations.
Low‐Dimensional Perovskites: From Synthesis to Stability in Perovskite Solar Cells
Authors: Yusoff Abd. Rashid bin Mohd. , Nazeeruddin Mohammad Khaja
Published: December 2017

Perovskite solar cells have been heralded as one of the most promising emerging technologies in 2016 because of the very high power conversion efficiency of 22% and the low cost of generating electricity compared to even fossil fuels. These are formed with various dimensionalities and can be fully manipulated once their bulk structure is reduced to a low‐dimensional structure. Despite being one of the most attractive materials to date, their instability significantly influences device performance and subsequently prevents the timely commercialization of perovskite solar cell technology. In this review, the recent advances in the synthesis of stable low‐dimensional metal‐halide perovskites are highlighted.
A Dipleiadiene‐Embedded Aromatic Saddle Consisting of 86 Carbon Atoms
Authors: Pun Sai Ho , Chan Chi Kit , Luo Jiye , Liu Zhifeng , Miao Qian
Published: December 2017

This study presents a new type of negatively curved nanographene (C86H32) that contains an unprecedented pattern of heptagons. A tert‐butylated derivative of C86H32 was successfully synthesized using tetrabenzodipleiadiene as a key building block. This synthesis involved a ring expansion reaction as a key step to form the seven‐membered rings in the framework of tetrabenzodipleiadiene. The single‐crystal structure reveals a saddle‐shaped molecule with a highly bent naphthalene moiety at the center of the polycyclic backbone. As found from the DFT calculations, this aromatic saddle is flexible at room temperature and has a saddle‐shaped geometry as the dominant conformation. The DFT calculations along with experimental results show that the attachment of t‐butyl groups to the central tetrabenzodipleiadiene moiety of nanographene C86H32 can stabilize the saddle conformation and make this nanographene less flexible.
Intracellular Delivery of Native Proteins Facilitated by Cell‐Penetrating Poly(disulfide)s
Authors: Qian Linghui , Fu Jiaqi , Yuan Peiyan , Du Shubo , Huang Wei , Li Lin , Yao Shao Q.
Published: December 2017

Intracellular delivery of therapeutic proteins is highly challenging and in most cases requires chemical or genetic modifications. Herein, two complementary approaches for endocytosis‐independent delivery of proteins to live mammalian cells are reported. By using either a “glycan” tag naturally derived from glycosylated proteins or a “traceless” tag that could reversibly label native lysines on non‐glycosylated proteins, followed by bioorthogonal conjugation with cell‐penetrating poly(disulfide)s (CPDs), we achieved intracellular delivery of proteins (including antibodies and enzymes) which, upon spontaneous degradation of CPDs, led to successful release of their “native” functional forms with immediate bioavailability.
Multi‐responses optimization of simultaneous adsorption of methylene blue and malachite green dyes in binary aqueous system onto Ni:FeO(OH)‐NWs‐AC using experimental design: derivative spectrophotometry method
Authors: Dil Ali Alipanahpour , Vafaei Azam , Ghaedi Abdol Mohammad , Ghaedi Mehrorang , Dil Ebrahim Alipanahpour
Published: December 2017

In this research, response surface methodology (RSM) approach using Central Composite Design (CCD) coupled by derivative spectrophotometry method was applied to develop mathematical model and optimize process parameters for simultaneous adsorption of methylene blue (MB) and malachite green (MG) from aqueous solution using Ni:FeO(OH)‐NWs‐AC. The optimal conditions to adsorption of MB and MG in binary mixture solution from aqueous solution were found at pH 8.0, MB concentration 20 mg L‐1, MG concentration 20 mg L‐1, adsorbent dosage 0.033 g and contact time 40 min. At these conditions, high adsorption efficiency (99.39% and 100.0% for MB and MG, respectively) was achieved. Among experimental equilibrium, Langmuir isotherm model fitted well with maximum monolayer adsorption capacity of 28.6 and 29.8 mg g‐1 for MB and MG, respectively. The adsorption kinetic data followed pseudo second‐order kinetics for MB and MG dyes.
Methanol activation catalyzed by Pt7, Pt3Cu4, and Cu7 clusters: A density functional theory investigation
Authors: Wei Aiwen , Feng Wei , Liu Huiling , Huang Xuri , Yang Guanghui
Published: December 2017

Metal clusters were considered as excellent catalysts for methanol dissociation. In this work, two main decomposition mechanisms of methanol on Pt7, Pt3Cu4, and Cu7 clusters were investigated by the density functional theory. One was methanol direct dehydrogenation, and the other was non‐CO‐involved oxidation. Stable adsorption configurations, elementary reaction barriers, the potential energy surface (PES), and the charge analysis were elucidated. The results showed that on Pt7 cluster, methanol was favorable for direct decomposition. On Pt3Cu4 and Cu7 clusters, methanol was inclined to the pathway of non‐CO‐involved oxidation. All the transition‐state energies and the final‐state energies were related in a linear, including those for the clusters. The results may be useful for computational design and catalysts optimization.
Interface engineering for the improvement of mechanical and thermal properties of covalent functionalized graphene/epoxy composites
Authors: Chhetri Suman , Adak Nitai Chandra , Samanta Pranab , Mallisetty Phani Kumar , Murmu Naresh Chandra , Kuila Tapas
Published: December 2017

Functionalized reduced graphene oxide (GO)/epoxy composites are fabricated through solution mixing. GO is functionalized using 3‐amino‐1,2,4‐triazole (TZ) in presence of potassium hydroxide (KOH). KOH is expected to serve dual role as catalyst for nucleophilic addition reaction between GO and TZ, and also as reducing agent. The grafting of TZ moiety on GO is confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The prepared composites show remarkable improvement in mechanical and thermal stability. The fracture toughness of the composites (critical stress intensity factor, KIC) achieved from single edge notched bending testing is improved by ∼111% against pure epoxy at 0.1 wt % loading of TZ functionalized GO. Further, the tensile strength and Young's modulus are improved by ∼30.5% and 35%, respectively. Thermal stability of the composites as investigated by thermogravimetric analysis showed 29 °C rise in onset degradation temperature for 0.1 wt % TZ functionalized GO incorporated composite. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46124.
Optical sensor based on fluorescent PMMA/PFO electrospun nanofibers for monitoring volatile organic compounds
Authors: Terra Idelma A. A. , Sanfelice Rafaela C. , Valente Gustavo T. , Correa Daniel S.
Published: December 2017

The development of polymeric materials with superior electrical and/or optical properties is highly demanded for designing optical gas sensors, where conjugated polymers play an important role due to their π‐electron conjugation. However, usually the low processability and high cost of these materials hinder technological applications. Here we report on a simple route to develop highly fluorescent electrospun nanofibers of poly(methyl methacrylate) (PMMA) containing low contents of polyfluorene (PFO). The PMMA_PFO nanofibers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, while the luminescence properties changes were evaluated by exposing the PMMA_PFO nanofibers to distinct volatile organic compounds (VOCs) including ethanol, toluene, tetrahydrofuran, acetone, dichloromethane, and chloroform. The changes in luminescence properties, specifically fluorescence quenching, of PMMA_PFO nanofibers were analyzed in terms of conformational changes from glassy‐phase to β‐phase of PFO when the nanofibers were exposed to the VOCs. The developed nanostructured platform showed a suitable response to detect chloroform, with linear responses in the concentration range from 10 to 300 ppm and from 350 to 500 ppm and limits of detection of 47.9 and 15.4 ppm, respectively. The results suggest the PMMA_PFO electrospun nanofibers are highly potential materials for optical gas sensor applications based on luminescence quenching. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46128.
Reprocessing of chromed ABS parts with chemical pickling and new chrome plating
Authors: Kurek Ana Paula , Moll Regis Garcia , Herbst Giulia , Dotto Marta Elisa Rosso , Sellin Noeli
Published: December 2017

In this work, chrome‐plated acrylonitrile–butadiene–styrene (ABS) parts containing defects in the deposited metal layer were pickled up to two times in hydrochloric and nitric acid under different immersion times. The influence of pickling on the properties of ABS was evaluated by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy–attenuated total reflection (FTIR–ATR), scanning electron microscopy, atomic force microscopy, and roughness. The pickled parts were again chromed and evaluated by visual inspection and adhesion. The metallic layer was removed and a slight yellowing of the samples surface with the increase of pickling time. There were no significant changes in the thermal behavior of the material. Some of the components of ABS were removed, as evidenced by the reduction of the absorption peaks intensity in FTIR–ATR, by the increase of roughness and presence of pores on the surface. With the increase of the immersion time and the number of pickling, there was the formation of pores with larger sizes and decrease in roughness, making metal–polymer adhesion difficult. Only one pickling, under immersion time of 30 min, was adequate for the removal of the metallic layer, allowing new chrome plating. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46131.
Interplay between key variables of peroxide cured EPDM and evaluation of electromechanical efficiency for MV cables
Authors: Radosavljević Jelena , Nikolić Ljubiša
Published: December 2017

Extensive work has been done on ethylene‐propylene‐diene monomer (EPDM) vulcanizates and the main factors influencing their cure efficiency. However, very little attention has been given to the evolution of material properties and the interplay between key variables formulation. The effect of ethylene/propylene content and concentration of peroxide and type on viscoelastic and dielectric properties of EPDM elastomers was investigated using dynamic mechanical analysis and electric property measurements at room temperature. In order to compare results, these measurements were obtained by FTIR spectroscopy. Differences between real and imaginary (loss) part of the permittivity of EPDM/ dicumyl peroxide (DCP) composites were more significant than those in EPDM/di(tert‐butylperoxyisopropyl)benzene (DTBPIB) composites. For peroxide DTBPIB, the dielectric percolation limit moves further with the increase of ethylene content of EPDM. The dielectric percolation limit of the peroxide DTBPIB is found to be approximately 60 g at a 75% of ethylene in EPDM. The FTIR analysis showed that a termoxidative degradation was promoted at mixes with peroxide DCP at 45 and 75% of ethylene in EPDM. Therefore, we could interestingly show the decrease in electrical properties particularly associated with termoxidative degradation of peroxide DCP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46139.
Differences in Safety of Nonsteroidal Antiinflammatory Drugs in Patients With Osteoarthritis and Patients With Rheumatoid Arthritis
Authors: Solomon Daniel H. , Husni M. Elaine , Wolski Katherine E. , Wisniewski Lisa M. , Borer Jeffrey S. , Graham David Y. , Libby Peter , Lincoff A. Michael , Lüscher Thomas F. , Menon Venu , Yeomans Neville D. , Wang Qiuqing , Bao Weihang , Berger Manuela F. , Nissen Steven E. ,   the PRECISION Trial Investigators
Published: December 2017

Objective

To determine the relative risks of cardiovascular (CV), gastrointestinal (GI), and renal adverse events during long‐term treatment with celecoxib, compared with ibuprofen and naproxen, in patients with osteoarthritis (OA) and patients with rheumatoid arthritis (RA).

Methods

A total of 24,081 patients with OA or RA who had a moderate or high risk for CV disease were enrolled internationally into a double‐blind randomized controlled trial. Interventions included celecoxib at a dosage of 100–200 mg twice daily, ibuprofen at a dosage of 600–800 mg 3 times daily, or naproxen at a dosage of 375–500 mg twice daily. The main outcomes were the first occurrence of a major adverse CV event, GI event, or renal event, and mortality.

Results

In the subgroup of patients with OA, the risk of a major adverse CV event was significantly reduced when celecoxib was compared with ibuprofen (hazard ratio [HR] 0.84, 95% confidence interval [95% CI] 0.72–0.99), but no significant difference was observed when celecoxib was compared with naproxen. In the RA subgroup, comparisons of celecoxib versus ibuprofen and celecoxib versus naproxen for the risk of major adverse CV events revealed HRs of 1.06 (95% CI 0.69–1.63) and 1.22 (95% CI 0.78–1.92), respectively. In the OA subgroup, comparisons of celecoxib versus ibuprofen for the risk of GI events showed an HR of 0.68 (95% CI 0.51–0.91), and a comparison of celecoxib versus naproxen showed an HR of 0.73 (95% CI 0.55–0.98). Duplicate comparisons in patients with RA revealed HRs of 0.48 (95% CI 0.22–1.07) and 0.54 (95% CI 0.24–1.24), respectively. In patients with OA, a comparison of celecoxib versus ibuprofen for the risk of renal events showed an HR of 0.58 (95% CI 0.40–0.82). In patients with RA, celecoxib treatment was associated with significantly lower mortality compared with naproxen treatment (HR 0.47, 95% CI 0.25–0.88).

Conclusion

Treatment with celecoxib at approved dosages conferred a similar or lower risk of CV, GI, and renal adverse events compared with treatment with ibuprofen or naproxen in patients with OA and patients with RA.
The Wnt Transcriptional Switch: TLE Removal or Inactivation?
Authors: Ramakrishnan Aravinda‐Bharathi , Sinha Abhishek , Fan Vinson B. , Cadigan Ken M.
Published: December 2017

Many targets of the Wnt/β‐catenin signaling pathway are regulated by TCF transcription factors, which play important roles in animal development, stem cell biology, and oncogenesis. TCFs can regulate Wnt targets through a “transcriptional switch,” repressing gene expression in unstimulated cells and promoting transcription upon Wnt signaling. However, it is not clear whether this switch mechanism is a general feature of Wnt gene regulation or limited to a subset of Wnt targets. Co‐repressors of the TLE family are known to contribute to the repression of Wnt targets in the absence of signaling, but how they are inactivated or displaced by Wnt signaling is poorly understood. In this mini‐review, we discuss several recent reports that address the prevalence and molecular mechanisms of the Wnt transcription switch, including the finding of Wnt‐dependent ubiquitination/inactivation of TLEs. Together, these findings highlight the growing complexity of the regulation of gene expression by the Wnt pathway.
Microfluidic platforms for the study of neuronal injury in vitro
Authors: Shrirao Anil B. , Kung Frank H. , Omelchenko Anton , Schloss Rene S. , Boustany Nada N. , Zahn Jeffrey D. , Yarmush Martin L. , Firestein Bonnie L.
Published: December 2017

Traumatic brain injury (TBI) affects 5.3 million people in the United States, and there are 12,500 new cases of spinal cord injury (SCI) every year. There is yet a significant need for in vitro models of TBI and SCI in order to understand the biological mechanisms underlying central nervous system (CNS) injury and to identify and test therapeutics to aid in recovery from neuronal injuries. While TBI or SCI studies have been aided with traditional in vivo and in vitro models, the innate limitations in specificity of injury, isolation of neuronal regions, and reproducibility of these models can decrease their usefulness in examining the neurobiology of injury. Microfluidic devices provide several advantages over traditional methods by allowing researchers to (1) examine the effect of injury on specific neural components, (2) fluidically isolate neuronal regions to examine specific effects on subcellular components, and (3) reproducibly create a variety of injuries to model TBI and SCI. These microfluidic devices are adaptable for modeling a wide range of injuries, and in this review, we will examine different methodologies and models recently utilized to examine neuronal injury. Specifically, we will examine vacuum‐assisted axotomy, physical injury, chemical injury, and laser‐based axotomy. Finally, we will discuss the benefits and downsides to each type of injury model and discuss how researchers can use these parameters to pick a particular microfluidic device to model CNS injury.
Hypoxia and transforming growth factor‐beta1 pathway activation promote Chinese Hamster Ovary cell aggregation
Authors: Qian Yueming , Rehmann Matthew S. , Qian Nan‐Xin , He Aiqing , Borys Michael C. , Kayne Paul S. , Li Zheng Jian
Published: December 2017

Suspension cultivation is the preferred mode of operation for the large‐scale production of many biologics. Chinese Hamster Ovary (CHO) cells are anchorage‐dependent in origin, but they have been widely adapted to suspension culture. In suspension culture, formation of CHO cell aggregates is a common phenomenon and compromises cell culture performance in multiple ways. To better understand the underlying mechanisms that regulate cell aggregation, we utilized CHO‐specific transcriptome profiling as a screening tool and demonstrated that many genes encoding extracellular matrix (ECM) proteins were upregulated in the cultures with increased cell aggregation. Significantly, hypoxia was identified to be a cause for promoting CHO cell aggregation, and transforming growth factor beta1 (TGFβ1) pathway activation served as an intermediate step mediating this biological cascade. These transcriptomics findings were confirmed by cell culture experiments, and it was further demonstrated that adding recombinant TGFβ1 to the culture significantly increased ECM protein fibronectin expression and cell aggregation. The results of this study emphasize the importance of adequate mixing and oxygen supply for suspension cultures from a new angle, and regulating the TGFβ1 pathway is proposed as a new strategy for mitigating cell aggregation to improve cell culture performance.
Experimental and Numerical Investigations of a Dual‐Stage Cyclone Separator
Authors: Zhang Ting , Guo Kai , Liu Chunjiang , Li Yue , Tao Min , Shen Chong
Published: December 2017

Cyclone separators can be utilized in parallel to increase particle collection efficiency. However, this leads to a maldistribution problem that causes separation performance deterioration. To improve the flow distribution, a dual‐stage multicyclone separator (DSCS) was designed, containing a tangential‐inlet circle pathway cyclone array, an axial‐inlet radiation pathway cyclone array, and a cylindrical outer chamber. Experimental and computational fluid dynamics results revealed the gas‐particle flow distribution through multicyclone arrays. Effects of flow distribution on particle deposition were investigated experimentally. Particle trajectories inside the cyclone separators were also observed. The multicyclone array proved to generate a uniform inlet velocity distribution. The proposed cyclone separator can be considered as an option to accomplish dilute gas‐particle separation.
Towards High‐Throughput Modelling of Copper Reactivity Induced by Structural Disorder in Amyloid Peptides
Authors: La Penna Giovanni , Li Mai Suan
Published: December 2017

Transition metal ions often interact with disordered proteins. The affinity is high enough to compete with structured proteins, but the catalytic activity of the metal centre is often out of control and, therefore, potentially dangerous for cells. An example is a single copper ion interacting with the amyloid‐β (Aβ) peptide and triplet dioxygen, an interaction that is fundamental in producing reactive oxygen species in neurodegeneration. High‐throughput modelling of the Cu‐Aβ‐O2 system was performed with the aim of providing a tool to dissect the structural features that characterise dangerous Cu‐based catalysts in neurodegeneration. This study showed that the production of superoxide is a process with low‐energy intermediate species, once a small population of high‐energy CuI‐Aβ complex is formed. This population is enhanced when Cu bridges two different peptides in 1:1 Cu:Aβ dimers. Despite the bias for high‐energy reduced reactant species, the reduction of CuII‐Aβ product by superoxide can also occur, in addition to that by ascorbate, because the structural disorder produces a small population of oxidant species characterised by unstable CuII coordination, coexisting with the most abundant reductant species, characterised by stable CuII coordination.
Stepwise Introduction of Cyano Groups into nido‐ and closo‐Undecaborate Clusters
Authors: Konieczka Szymon Z. , Schlüter Florian , Sindorf Christoph , Kerpen Christoph , Bernhardt Eduard , Finze Maik
Published: December 2017

Eleven‐vertex closo and nido boron clusters with one or two exo‐cyano groups were obtained by a series of consecutive cage‐opening and cage‐closure reactions starting from K2[closo‐B11H11] (K21). In the first step, K21 reacts with KCN in water at elevated temperatures to yield [7‐NC‐nido‐B11H12]2− (5 a). Oxidation of 5 a with PbO2 gives [NC‐closo‐B11H10]2− (2). In analogous subsequent reactions, dianion 2 was converted with KCN regioselectively to [7,9‐(NC)2‐nido‐B11H11]2− (6 a), which was further oxidized to [(NC)2‐closo‐B11H9]2− (3). The {nido‐B11} dianions 5 a and 6 a were protonated to yield [7‐NC‐nido‐B11H13]− (5 b) and [7,9‐(NC)2‐nido‐B11H12]− (6 b). All anions were studied by NMR spectroscopy and, except for 6 b, salts of all anions were characterized by IR and Raman spectroscopy and by elemental analysis. The position of the cyano group(s) in 5 a and 6 a were confirmed by NMR data and single‐crystal X‐ray diffraction studies on [Ph4P]25 a⋅CH2Cl2 and [Et4N]26 a. The {closo‐B11} clusters are fluxional in solution. In the crystal of [EMIm]22 the BCN vertex is in the 2‐position. Two isomers of dianion 3, [2,3‐(NC)2‐closo‐B11H9]2− and [2,6‐(NC)2‐closo‐B11H9]2−, were identified in the crystal of its [Et4N]+ salt. The peak oxidation potentials Epa of anions 1–3, 5 a, 6 a, 5 b, and [nido‐B11H14]− (4 b), determined by cyclic voltammetry, increase with increasing number of cyano groups. Increasing Epa in the order 1<2<3 parallels the increasing reactivity toward cyanide anions.
Analysis of censored data under heteroscedastic transformation regression models with unknown transformation function
Authors: Wang Qihua , Wang Xuan
Published: December 2017

Consider a censored heteroscedastic transformation regression model where both the transformation function and the error distribution function are completely unknown. A method is developed to estimate the transformation function, the regression parameter vector, and the single index parameter vector of the variance function by establishing an expression for the transformation function and two estimating equations for both the parameter vectors. It is shown that the estimator of the transformation function converges weakly to a mean zero Gaussian process, and the parametric estimators are asymptotically normal. All the estimators converge to their true values in probability at a rate proportional to . Simulation studies are conducted to evaluate the finite sample behaviour of the proposed estimators, and a real data analysis is used to illustrate the proposed estimating method. The Canadian Journal of Statistics 46: 233–245; 2018 © 2017 Statistical Society of Canada
Empirical likelihood inference for multiple censored samples
Authors: Cai Song , Chen Jiahua
Published: December 2017

We present a semiparametric approach to inference on the underlying distributions of multiple right‐ and/or left‐censored samples with fixed censoring points and focus on effective estimation of population quantiles and distribution functions. We pool information across multiple censored samples through a semiparametric density ratio model and propose an empirical likelihood approach to inference. This approach achieves high efficiency without making restrictive model assumptions. The resultant estimator is asymptotically normal, and the resulting distribution function estimator and quantile estimator are more efficient than estimators obtained from the classic nonparametric methods, such as the empirical distribution and sample quantile. In addition, the proposed approach permits consistent estimation of distribution functions and quantiles on a larger domain than would otherwise be possible using the classic methods. Simulation studies suggest that the proposed method is robust against misspecification of the density ratio function and against outliers. Our approach is further illustrated with an application to the analysis of real lumber strength data. The Canadian Journal of Statistics 46: 212–232; 2018 © 2017 Statistical Society of Canada
Incidence of thromboembolic and bleeding events in patients with newly diagnosed nonvalvular atrial fibrillation: An Asian multicenter retrospective cohort study in Singapore
Authors: Wee Xue Ting , Ho Lih Maan , Ho Han Kiat , Lee Joyce Yu‐Chia , Yap Chun Wei , William Henry , Chan Linus Chong En , Tay Hooi Ching , Goh Cynthia Eei Mei , Tan Doreen Su‐Yin
Published: December 2017

Background

Real‐world effectiveness and safety of antithrombotics in nonvalvular atrial fibrillation (NVAF) patients in Singapore has not been thoroughly studied.

Hypothesis.

Users of various antithrombotics experience a significantly different risk of stroke and major bleed compared with warfarin users.

Methods

This multicenter retrospective cohort study included patients age ≥ 21 years newly diagnosed with NVAF between July 2012 and September 2015. Using electronic medical records, data on patients' demographics, antithrombotics prescribed, and CHA2DS2‐VASc and HAS‐BLED risk factors were collected. Patients were followed for 1 year from diagnosis for the primary effectiveness and safety endpoints of incident stroke or systemic embolism and major bleed, respectively. The secondary safety endpoint was overall bleed. Hazard ratios (HR) were determined from Cox regression.

Results

Of 743 patients included, 224 were on warfarin, 156 on direct oral anticoagulants (DOACs), 277 on single antiplatelet therapy (SAPT), 28 on dual antiplatelet therapy (DAPT), and 58 on no therapy. Mean age (±SD) was 68.7 ± 13.0 years. Compared with warfarin users, SAPT (adjusted [adj.] HR: 3.70, 95% confidence interval [CI]: 1.21‐11.3) and DAPT users (adj. HR: 10.1, 95% CI: 1.51‐67.2) were more likely to develop thromboembolic outcomes. Also, DOAC users (adj. HR: 0.304, 95% CI: 0.158‐0.585), SAPT users (adj. HR: 0.142, 95% CI: 0.0680‐0.295), and DAPT users (adj. HR: 0.112, 95% CI: 0.0146‐0.857) were less likely to experience any bleed compared with warfarin users.

Conclusions

SAPT and DAPT are less effective than warfarin in NVAF patients. DOACs may be considered in view of lower risk of overall bleed.
Acute kidney injury post–transcatheter aortic valve replacement
Authors: Ram Pradhum , Mezue Kenechukwu , Pressman Gregg , Rangaswami Janani
Published: December 2017

Transcatheter aortic valve replacement (TAVR) is a treatment option in high‐risk patients with severe aortic stenosis who are not surgical candidates. In light of emerging evidence, it is being increasingly performed even in intermediate‐risk patients in recent years. Patients who develop acute kidney injury (AKI) following TAVR are known to have worse outcomes. The objective of this concise review was to identify the prevalence and the impact of AKI following TAVR on patient outcomes by including the most recent literature in our search. After a thorough search on MEDLINE, Google Scholar, and PubMed, we included all literature relevant to AKI following TAVR. We found that AKI was caused by a variety of reasons, such as hemodynamic instability during rapid pacing, blood transfusion, periprocedural embolization, and use of contrast medium, to name a few. In patients who developed AKI following TAVR, 30‐day and 1‐year mortality were increased. Further, in these patients, length and cost of hospital stay were increased as well. Preventive measures such as optimal periprocedural hydration, careful contrast use, and techniques to prevent embolization during device implantation have been tried with limited success. Given that TAVR is expected to be increasingly performed, this review aimed to summarize the rapidly expanding currently available literature in an effort to reduce procedural complications and thereby improve patient outcomes.
Laboratory characteristics of ischemic stroke patients with atrial fibrillation on or off therapeutic warfarin
Authors: Aachi Raghav V. , Birnbaum Lee A. , Topel Christopher H. , Seifi Ali , Hafeez Shaheryar , Behrouz Réza
Published: December 2017

Background

In patients with atrial fibrillation (AF), despite adequate anticoagulation, ischemic stroke (IS) is an uncommon yet concerning occurrence.

Hypothesis

Specific laboratory parameters may affect the efficacy of warfarin despite therapeutic international normalized ratio (INR) in patient with AF who present with IS.

Methods

We used the database from a multicenter clinical trial to identify AF patients who presented with IS. We trichotomized the cohort into patients with therapeutic INR on warfarin, subtherapeutic INR on warfarin, and on no anticoagulants. We then compared baseline laboratory characteristics and other baseline features among the groups.

Results

Patients with therapeutic INR presented with higher serum creatinine (P = 0.01) and blood urea nitrogen (P = 0.02) and lower glomerular filtration rates (P = 0.001) compared with other groups. Other laboratory parameters were not different among the 3 groups. Patients with therapeutic INR also presented with milder stroke symptoms (P = 0.01). Medical history of the 3 groups was not different, except for history of valvular heart disease, which was more prevalent in patients with therapeutic INR (P = 0.004). In‐hospital mortality rates and 90‐day disability were not different among the 3 groups.

Conclusions

AF patients who presented with IS on therapeutic warfarin had higher average serum creatinine and blood urea nitrogen, and lower glomerular filtration rates, compared with others. Impaired renal function may be a factor contributing to occurrence of IS in AF patients despite adequate anticoagulation. Larger, targeted studies are needed to confirm these findings.
Most impactful factors on the health‐related quality of life of a geriatric population with cancer
Authors: Pisu Maria , Azuero Andres , Halilova Karina I. , Williams Courtney P. , Kenzik Kelly M. , Kvale Elizabeth A. , Williams Grant R. , Meneses Karen , Sullivan Margaret , Yagnik Supriya Kumar , Goertz Hans‐Peter , Rocque Gabrielle B.
Published: December 2017

BACKGROUND

As the population of older adults with cancer continues to grow, the most important factors contributing to their health‐related quality of life (HRQOL) remain unclear.

METHODS

A total of 1457 older adults (aged ≥65 years) with cancer participated in a telephone survey. Outcomes were measured using the Physical Component Summary (PCS) and Mental Component Summary (MCS) scores of the 12‐Item Short Form Survey (SF‐12) from the Medical Outcomes Study (version 2). Statistical techniques used to identify factors in 4 domains (physical, psychological, social, and spiritual) most strongly associated with HRQOL included linear models, recursive partitioning, and random forests. Models were developed in a training data set (920 respondents) and performance was assessed in a validation data set (537 respondents).

RESULTS

Respondents were a median of 19 months from diagnosis, and 28.1% were receiving active treatment. The most relevant factors found to be associated with PCS were symptom severity, comorbidity scores, leisure‐time physical activity, and having physical support needs. The most relevant factors for MCS were having emotional support needs, symptom severity score, and the number of financial hardship events. Results were consistent across modeling techniques. Symptoms found to be strongly associated with PCS included fatigue (adjusted proportion of summary score's variance [R2] = 0.34), pain (adjusted R2 = 0.32), disturbed sleep (adjusted R2 = 0.16), and drowsiness (adjusted R2 = 0.16). Symptoms found to be strongly associated with MCS included fatigue (adjusted R2 = 0.23), problems remembering things (adjusted R2 = 0.17), disturbed sleep (adjusted R2 = 0.16), and lack of appetite (adjusted R2 = 0.16).

CONCLUSIONS

The findings of the current study support the importance of addressing persistent symptoms, managing comorbidities, promoting leisure‐time physical activity, and addressing financial challenges. A long‐term comprehensive approach is needed to ensure the well‐being of older adults with cancer. Cancer 2018;124:596‐605. © 2017 American Cancer Society.
The Independent Gradient Model: A New Approach for Probing Strong and Weak Interactions in Molecules from Wave Function Calculations
Authors: Lefebvre Corentin , Khartabil Hassan , Boisson Jean‐Charles , Contreras‐García Julia , Piquemal Jean‐Philip , Hénon Eric
Published: December 2017

Extraction of the chemical interaction signature from local descriptors based on electron density (ED) is still a fruitful field of development in chemical interpretation. In a previous work that used promolecular ED (frozen ED), the new descriptor,
, was defined. It represents the difference between a virtual upper limit of the ED gradient (
, IGM=independent gradient model) that represents a noninteracting system and the true ED gradient (
). It can be seen as a measure of electron sharing brought by ED contragradience. A compelling feature of this model is to provide an automatic workflow that extracts the signature of interactions between selected groups of atoms. As with the noncovalent interaction (NCI) approach, it provides chemists with a visual understanding of the interactions present in chemical systems.
is achieved simply by using absolute values upon summing the individual gradient contributions that make up the total ED gradient. Hereby, we extend this model to relaxed ED calculated from a wave function. To this end, we formulated gradient‐based partitioning (GBP) to assess the contribution of each orbital to the total ED gradient. We highlight these new possibilities across two prototypical examples of organic chemistry: the unconventional hexamethylbenzene dication, with a hexa‐coordinated carbon atom, and β‐thioaminoacrolein. It will be shown how a bond‐by‐bond picture can be obtained from a wave function, which opens the way to monitor specific interactions along reaction paths.
Past disturbances and intraspecific competition as drivers of spatial pattern in primary spruce forests
Authors: Després T. , Vítková L. , Bače R. , Čada V. , Janda P. , Mikoláš M. , Schurman J. S. , Trotsiuk V. , Svoboda M.
Published: December 2017

The role of density dependence in shaping spatial patterns in tree distributions presumably changes throughout stand development. However, empirical investigations into developmental processes are often limited by a lack of long‐term data on disturbance history, which further limits the ability to assess the role of spatial variation in site conditions (e.g., slope, aspect, mean annual temperature). This study included data from 289 plots within 26 primary forest stands of the Carpathian Mountains; stands were dominated by Norway spruce (Picea abies) and driven by mixed‐severity disturbance regimes. We assessed spatial patterns in living tree positions, tree diameters, and the relative position of living trees to dead trees. Random forest classification was used to discriminate between disturbance history, tree density, and site conditions and their effects on the observed spatial patterns. At the stand scale, distances between trees of equal diameter were more uniform that expected (tree diameter was showing repulsion), while tree positions and dead trees were mostly distributed randomly. The processes that best explained the spatial patterns were identified as self‐thinning mortality and past disturbances (100–150 yr). This study demonstrated that the plot and stand‐scale spatial patterns resulted from the combination of past disturbances and density‐dependent legacies derived from earlier forest development stages.
Atrioventricular junction ablation in patients with atrial fibrillation treated with cardiac resynchronization therapy: positive impact on ventricular arrhythmias, implantable cardioverter‐defibrillator therapies and hospitalizations
Authors: Gasparini Maurizio , Kloppe Axel , Lunati Maurizio , Anselme Frédéric , Landolina Maurizio , Martinez‐Ferrer Jose Bautista , Proclemer Alessandro , Morani Giovanni , Biffi Mauro , Ricci Renato , Rordorf Roberto , Mangoni Lorenza , Manotta Laura , Grammatico Andrea , Leyva Francisco , Boriani Giuseppe
Published: December 2017

Aims

We sought to determine whether atrioventricular junction ablation (AVJA) in patients with cardiac resynchronization therapy (CRT) implantable cardioverter‐defibrillator (ICD) and with permanent atrial fibrillation (AF) has a positive impact on ICD shocks and hospitalizations compared with rate‐slowing drugs.

Methods and results

This is a pooled analysis of data from 179 international centres participating in two randomized trials and one prospective observational research. The co‐primary endpoints were all‐cause ICD shocks and all‐cause hospitalizations. Out of 3358 CRT‐ICD patients (2720 male, 66.6 years), 2694 (80%) were in sinus rhythm (SR) and 664 (20%) had permanent AF—262 (8%) treated with AVJA (AF + AVJA) and 402 (12%) treated with rate‐slowing drugs (AF + Drugs). Median follow‐up was 18 months. The mean (95% confidence intervals) annual rate of all‐cause ICD shocks per 100 patient years was 8.0 (5.3–11.9) in AF + AVJA, 43.6 (37.7–50.4) in AF + Drugs, and 34.4 (32.5–36.5) in SR patients, resulting in incidence rate ratio (IRR) reductions of 0.18 (0.10–0.32) for AF + AVJA vs. AF + Drugs (P < 0.001) and 0.48 (0.35–0.66) for AF + AVJA vs. SR (P < 0.001). These reductions were driven by significant reductions in both appropriate ICD shocks [IRR 0.23 (0.13–0.40), P < 0.001, vs. AF + Drugs] and inappropriate ICD shocks [IRR 0.09 (0.04–0.21), P < 0.001, vs. AF + Drugs]. Annual rate of all‐cause hospitalizations was significantly lower in AF + AVJA vs. AF + Drugs [IRR 0.57 (0.41–0.79), P < 0.001] and SR [IRR 0.85 (073–0.98), P = 0.027].

Conclusion

In AF patients treated with CRT, AVJA results in a lower incidence and burden of all‐cause, appropriate and inappropriate ICD shocks, as well as to fewer all‐cause and heart failure hospitalizations.

Clinical Trial Registration: NCT00147290, NCT00617175, NCT01007474.