bluuebunny/crossref_metadata_2025_split huggingface dataset:
2D Perovskites with Short Interlayer Distance for High‐Performance Solar Cell Application
Authors: Ma Chunqing , Shen Dong , Ng Tsz‐Wai , Lo Ming‐Fai , Lee Chun‐Sing 
Published: April 2018

Abstract2D perovskites have emerged as one of the most promising photovoltaic materials owing to their excellent stability compared with their 3D counterparts. However, in typical 2D perovskites, the highly conductive inorganic layers are isolated by large organic cations leading to quantum confinement and thus inferior electrical conductivity across layers. To address this issue, the large organic cations are replaced with small propane‐1,3‐diammonium (PDA) cations to reduce distance between the inorganic perovskite layers. As shown by optical characterizations, quantum confinement is no longer dominating in the PDA‐based 2D perovskites. This leads to considerable enhancement of charge transport as confirmed with electrochemical impedance spectroscopy, time‐resolved photoluminescence, and mobility measurements. The improved electric properties of the interlayer‐engineered 2D perovskites yield a power conversion efficiency of 13.0%. Furthermore, environmental stabilities of the PDA‐based 2D perovskites are improved. PDA‐based 2D perovskite solar cells (PSCs) with encapsulation can retain over 90% of their efficiency upon storage for over 1000 h, and PSCs without encapsulation can maintain their initial efficiency at 70 °C for over 100 h, which exhibit promising stabilities. These results reveal excellent optoelectronic properties and intrinsic stabilities of the layered perovskites with reduced interlayer distance.
Iridescent Chiral Nematic Mesoporous Organosilicas with Alkylene Spacers
Authors: Terpstra Andrea S. , Arnett Loryn P. , Manning Alan P. , Michal Carl A. , Hamad Wadood Y. , MacLachlan Mark J. 
Published: April 2018

AbstractMesoporous organosilica films with chiral nematic structures are prepared with a bridging urea group and with alkylene bridges, where the length of the alkylene bridge varies from C1–C6. To synthesize these materials, cellulose nanocrystals (CNCs) are used as liquid crystal templates, which coassemble with the organosilica precursor to give composite materials with a chiral nematic structure of CNCs embedded within. Removal of the CNCs by acid hydrolysis results in free‐standing, mesoporous organosilica films with long‐range chiral nematic ordering of the porous network. It is found that increasing the length of the organosilica bridging groups causes phase separation between the organosilica precursors and the aqueous CNC suspension. This problem is solved through two distinct methods: combining the long alkylene‐bridged precursors with shorter precursors or by using a mixed solvent system of water and dimethylformamide during self‐assembly. The new chiral nematic mesoporous organosilica films display photonic properties, good thermal stabilities, and interconnected pore structures.
Copper Mediated Three‐Component Reactions of Alkynes, Azides, and Propargylic Carbonates: Synthesis of 5‐Allenyl‐1,2,3‐Triazoles
Authors: Wu Feifei , Zhou Wei , Chen Kai , Chen Wanzhi , Liu Miaochang , Wu Huayue 
Published: April 2018

AbstractA copper‐mediated one‐pot sequential reaction of terminal alkynes, azides, and propargylic carbonates is reported. The three component reaction occurs readily at room temperature to afford a 5‐allenyl‐1,2,3‐triazoles in high yields, providing a straightforward approach to 1,3,5‐trisubstituted triazoles using easily available Cu(I) reagent.magnified image
3D Visible‐Light Invisibility Cloak
Authors: Zheng Bin , Zhu Rongrong , Jing Liqiao , Yang Yihao , Shen Lian , Wang Huaping , Wang Zuojia , Zhang Xianmin , Liu Xu , Li Erping , Chen Hongsheng 
Published: April 2018

AbstractThe concept of an invisibility cloak is a fixture of science fiction, fantasy, and the collective imagination. However, a real device that can hide an object from sight in visible light from absolutely any viewpoint would be extremely challenging to build. The main obstacle to creating such a cloak is the coupling of the electromagnetic components of light, which would necessitate the use of complex materials with specific permittivity and permeability tensors. Previous cloaking solutions have involved circumventing this obstacle by functioning either in static (or quasistatic) fields where these electromagnetic components are uncoupled or in diffusive light scattering media where complex materials are not required. In this paper, concealing a large‐scale spherical object from human sight from three orthogonal directions is reported. This result is achieved by developing a 3D homogeneous polyhedral transformation and a spatially invariant refractive index discretization that considerably reduce the coupling of the electromagnetic components of visible light. This approach allows for a major simplification in the design of 3D invisibility cloaks, which can now be created at a large scale using homogeneous and isotropic materials.
Recent advances in treatment for colorectal liver metastasis
Authors: Oki Eiji , Ando Koji , Nakanishi Ryota , Sugiyama Masahiko , Nakashima Yuichiro , Kubo Nobuhide , Kudou Kensuke , Saeki Hiroshi , Nozoe Tadahiro , Emi Yasunori , Maehara Yoshihiko 
Published: April 2018

AbstractA major challenge for the management of colorectal liver metastasis (CRLM) is the multidisciplinary approach including surgery. Resection is the most important treatment strategy to prolong the survival of patients with colorectal cancer (CRC). Even when resection is not possible as a primary treatment, it may still be carried out for curative intent after effective chemotherapy. Therefore, resection should always be considered when conducting chemotherapy for CRLM. Neoadjuvant anti‐epidermal growth factor receptor (EGFR) antibody has shown a high response rate for RAS wild CRC. However, whether anti‐EGFR antibody is superior to antivascular endothelial growth factor antibody for all types of CRLM is yet to be determined. Recently, several randomized control trials of first‐line therapy for advanced CRC have been conducted, and some of them are ongoing. The optimal chemotherapy regimen and tumor biology indicated for neoadjuvant chemotherapy as well as conversion surgery are expected to be determined in the near future.
Phylogenomics reveals an extensive history of genome duplication in diatoms (Bacillariophyta)
Authors: Parks Matthew B. , Nakov Teofil , Ruck Elizabeth C. , Wickett Norman J. , Alverson Andrew J. 
Published: April 2018

Premise of the StudyDiatoms are one of the most species‐rich lineages of microbial eukaryotes. Similarities in clade age, species richness, and primary productivity motivate comparisons to angiosperms, whose genomes have been inordinately shaped by whole‐genome duplication (WGD). WGDs have been linked to speciation, increased rates of lineage diversification, and identified as a principal driver of angiosperm evolution. We synthesized a large but scattered body of evidence that suggests polyploidy may be common in diatoms as well.MethodsWe used gene counts, gene trees, and distributions of synonymous divergence to carry out a phylogenomic analysis of WGD across a diverse set of 37 diatom species.Key ResultsSeveral methods identified WGDs of varying age across diatoms. Determining the occurrence, exact number, and placement of events was greatly impacted by uncertainty in gene trees. WGDs inferred from synonymous divergence of paralogs varied depending on how redundancy in transcriptomes was assessed, gene families were assembled, and synonymous distances (Ks) were calculated. Our results highlighted a need for systematic evaluation of key methodological aspects of Ks‐based approaches to WGD inference. Gene tree reconciliations supported allopolyploidy as the predominant mode of polyploid formation, with strong evidence for ancient allopolyploid events in the thalassiosiroid and pennate diatom clades.ConclusionsOur results suggest that WGD has played a major role in the evolution of diatom genomes. We outline challenges in reconstructing paleopolyploid events in diatoms that, together with these results, offer a framework for understanding the impact of genome duplication in a group that likely harbors substantial genomic diversity.
A time to be born: Variation in the hour of birth in a rural population of Northern Argentina
Authors: Chaney Carlye , Goetz Teddy G. , Valeggia Claudia 
Published: April 2018

ObjectivesThe present study aimed at investigating the timing of birth across the day in a rural population of indigenous and nonindigenous women in the province of Formosa, Argentina in order to explore the variation in patterns in a non‐Western setting.Materials and methodsThis study utilized birth record data transcribed from delivery room records at a rural hospital in the province of Formosa, northern Argentina. The sample included data for Criollo, Wichí, and Toba/Qom women (n = 2421). Statistical analysis was conducted using directional statistics to identify a mean sample direction. Chi‐square tests for homogeneity were also used to test for statistical significant differences between hours of the day.ResultsThe mean sample direction was 81.04°, which equates to 5:24 AM when calculated as time on a 24‐hr clock. Chi‐squared analyses showed a statistically significant peak in births between 12:00 and 4:00 AM. Birth counts generally declined throughout the day until a statistically significant trough around 5:00 PM.DiscussionThis pattern may be associated with the circadian rhythms of hormone release, particularly melatonin, on a proximate level. At the ultimate level, giving birth in the early hours of the morning may have been selected to time births when the mother could benefit from the predator protection and support provided by her social group as well as increased mother‐infant bonding from a more peaceful environment.
Distinct Electron Conductance Regimes in Bacterial Decaheme Cytochromes
Authors: Barrozo Alexandre , El‐Naggar Mohamed Y. , Krylov Anna I. 
Published: April 2018

AbstractShewanella oneidensis MR‐1 gains energy by extracellular electron transfer to solid surfaces. They employ c‐type cytochromes in two Mtr transmembrane complexes, forming a multiheme wire for electron transport across the cellular outer membrane. We investigated electron‐ and hole‐transfer mechanisms in the external terminal of the two complexes, MtrC and MtrF. Comparison of computed redox potentials with previous voltammetry experiments in distinct environments (isolated and electrode‐bound conditions of PFV or in vivo) suggests that these systems function in different regimes depending on the environment. Analysis of redox potential shifts in different regimes indicates strong coupling between the hemes via an interplay between direct Coulomb and indirect interactions through local structural reorganization. The latter results in the screening of Coulomb interactions and explains poor correlation of the strength of the heme‐to‐heme interactions with the distance between the hemes.
Dynamic Interfacial Adhesion through Cucurbit[n]uril Molecular Recognition
Authors: Liu Ji , Tan Cindy Soo Yun , Scherman Oren A. 
Published: April 2018

AbstractSupramolecular building blocks, such as cucurbit[n]uril (CB[n])‐based host–guest complexes, have been extensively studied at the nano‐ and microscale as adhesion promoters. Herein, we exploit a new class of CB[n]‐threaded highly branched polyrotaxanes (HBP‐CB[n]) as aqueous adhesives to macroscopically bond two wet surfaces, including biological tissue, through the formation of CB[8] heteroternary complexes. The dynamic nature of these complexes gives rise to adhesion with remarkable toughness, displaying recovery and reversible adhesion upon mechanical failure at the interface. Incorporation of functional guests, such as azobenzene moieties, allows for stimuli‐activated on‐demand adhesion/de‐adhesion. Macroscopic interfacial adhesion through dynamic host–guest molecular recognition represents an innovative strategy for designing the next generation of functional interfaces, biomedical devices, tissue adhesives, and wound dressings.
In‐situ‐Methoden zur Charakterisierung elektrochemischer NiFe‐Sauerstoffentwicklungskatalysatoren
Authors: Zhu Kaiyue , Zhu Xuefeng , Yang Weishen 
Published: April 2018

AbstractNiFe‐Materialien sind hervorragende Elektrokatalysatoren für die Sauerstoffentwicklungsreaktion (OER). Zur Entwicklung effizienterer Katalysatoren werden umfangreichere Kenntnisse zur Aktivitätssteigung der OER sowie über deren Mechanismus benötigt. Dafür sind In‐situ‐Charakterisierungsmethoden erforderlich, die Untersuchungen unter OER‐Bedingungen ermöglichen, um Zwischenprodukte der OER sowie OER‐aktive Zentren und Phasen zu identifizieren. In diesem Kurzaufsatz werden die neuesten Fortschritte bei der In‐situ‐Charakterisierung von NiFe‐basierten Elektrokatalysatoren mit Raman‐Spektroskopie, XAS, APXPS, Mößbauer‐Spektroskopie, UV/Vis‐Spektroskopie, DEMS und SI‐SECM zusammengefasst. Die Ergebnisse belegen nicht nur die Strukturumwandlung und fortschreitende Oxidation der katalytischen Spezies unter OER‐Bedingungen, sondern auch die entscheidende Rolle von Ni und Fe. Die Notwendigkeit für die Entwicklung neuer In‐situ‐Methoden und Rechnungen zum OER‐Mechanismus für die gezielte Entwicklung neuer, hochaktiver OER‐Elektrokatalysatoren wird diskutiert.
Genetically Engineered Supercharged Polypeptide Fluids: Fast and Persistent Self‐Ordering Induced by Touch
Authors: Zhang Lei , Ma Chao , Sun Jing , Shao Baiqi , Portale Giuseppe , Chen Dong , Liu Kai , Herrmann Andreas 
Published: April 2018

AbstractMechanically induced disorder–order transitions have been studied in fluid surfactant solutions or polymer thermotropic liquid crystals. However, isothermally induced ordered phases do not persist after cessation of shear, which limits their technological applicability. Moreover, no such stimuli‐responsive materials involving biomacromolecules have been reported although biopolymer liquids are gaining a lot of attention. A biological fluid system is introduced in which anionic polypeptides are complexed with cationic surfactants. The resulting fluids exhibited very sensitive isotropic–nematic transition triggered by shear. The formed liquid crystal was preserved after cessation of mechanical stimulus. Self‐ordering behavior of the material was achieved through water flow and finger pressing. The latter mechanical induction resulted in the formation of complex pattern that can be read out by birefringence, allowing the recording of fingerprint information.
Development of the Vinylogous Pictet–Spengler Cyclization and Total Synthesis of (±)‐Lundurine A
Authors: Nash Aaron , Qi Xiangbing , Maity Pradip , Owens Kyle , Tambar Uttam K. 
Published: April 2018

AbstractA novel vinylogous Pictet–Spengler cyclization has been developed for the generation of indole‐annulated medium‐sized rings. The method enables the synthesis of tetrahydroazocinoindoles with a fully substituted carbon center, a prevalent structural motif in many biologically active alkaloids. The strategy has been applied to the total synthesis of (±)‐lundurine A.
Highly Efficient and Stereoselective Thioallylation of Alkynes: Possible Gold Redox Catalysis with No Need for a Strong Oxidant
Authors: Wang Jin , Zhang Shuyao , Xu Chang , Wojtas Lukasz , Akhmedov Novruz G. , Chen Hao , Shi Xiaodong 
Published: April 2018

AbstractStereoselective thioallylation of alkynes under possible gold redox catalysis was accomplished with high efficiency (as low as 0.1 % catalyst loading, up to 99 % yield) and broad substrate scope (various alkynes, inter‐ and intramolecular fashion). The gold(I) catalyst acts as both a π‐acid for alkyne activation and a redox catalyst for AuI/III coupling, whereas the sulfonium cation generated in situ functions as a mild oxidant. This novel methodology provides an exciting system for gold redox catalysis without the need for a strong oxidant.
Ultrathin Chiral Metal–Organic‐Framework Nanosheets for Efficient Enantioselective Separation
Authors: Guo Jun , Zhang Yin , Zhu Yanfei , Long Chang , Zhao Meiting , He Meng , Zhang Xiaofei , Lv Jiawei , Han Bing , Tang Zhiyong 
Published: April 2018

AbstractChiral metal–organic framework (CMOF) nanosheets only a few layers thick remain a virgin land waiting for exploration. Herein, the first examples of ultrathin CMOF nanosheets are prepared by the confinement growth of two‐dimensional (2D) chiral layers, which are assembled by helical metal–organic chains within microemulsion. This convenient and easily scaled up inverse microemulsion method gives a series of 2D CMOF nanosheets composed of variable metal nodes or chiral ligands. More significantly, thanks to the exceptionally large number of chiral sites exposed on surfaces, the as‐obtained CMOF nanosheets exhibit much higher enantioselectivity in chiral separation compared with their bulk counterparts.
Oxidation Catalysis by an Aerobically Generated Dess–Martin Periodinane Analogue
Authors: Maity Asim , Hyun Sung‐Min , Wortman Alan K. , Powers David C. 
Published: April 2018

AbstractHypervalent iodine(V) reagents, such as Dess–Martin periodinane (DMP) and 2‐iodoxybenzoic acid (IBX), are broadly useful oxidants in chemical synthesis. Development of strategies to generate these reagents from dioxygen (O2) would immediately enable use of O2 as a terminal oxidant in a broad array of substrate oxidation reactions. Recently we disclosed the aerobic synthesis of I(III) reagents by intercepting reactive oxidants generated during aldehyde autoxidation. In this work, aerobic oxidation of iodobenzenes is coupled with disproportionation of the initially generated I(III) compounds to generate I(V) reagents. The aerobically generated I(V) reagents exhibit substrate oxidation chemistry analogous to that of DMP. The developed aerobic generation of I(V) has enabled the first application of I(V) intermediates in aerobic oxidation catalysis.
Iron‐catalyzed cross‐coupling reaction: Heterogeneous palladium and copper‐free Heck and Sonogashira cross‐coupling reactions catalyzed by a reusable Fe(III) complex
Authors: Hajipour Abdol R. , Abolfathi Parisa , Tavangar‐Rizi Zeinab 
Published: April 2018

An interesting silica‐supported iron catalyst was successfully prepared and demonstrated as an efficient heterogeneous catalyst for cross‐coupling reactions of aryl halides. The as‐prepared nanocatalyst was well characterized and found to be highly efficient in Heck reaction under mild and sustainable conditions (water as solvent at 80 °C in short reaction time). Furthermore, the obtained catalyst was used as an efficient, inexpensive and green heterogeneous catalyst for Sonogashira cross‐coupling reactions of various aryl iodides and provided the corresponding products with moderate to good yields. This phosphine, copper and palladium‐free catalyst was simply recovered from the reaction mixture and recycled five times without substantial decrease in its catalytic activity.
Structurally characterized homotrinuclear Salamo‐type nickel(II) complexes: Synthesis, solvent effect and fluorescence properties
Authors: Kang Quan‐Peng , Li Xiao‐Yan , Zhao Qing , Ma Jian‐Chun , Dong Wen‐Kui 
Published: April 2018

Four new solvent‐induced Ni(II) complexes with chemical formulae [{NiL(μ2‐OAc)(MeOH)}2Ni]·2MeOH (1), [{NiL(μ2‐OAc)}2(n‐PrOH)(H2O)Ni]·n‐PrOH (2), [{NiL(μ2‐OAc)(DMF)}2Ni] (3) and [{NiL(μ2‐OAc)(DMSO)}2Ni]·2DMSO (4), (H2L = 4‐Nitro‐4′‐chloro‐2,2′‐[(1,3‐propylene)dioxybis(nitrilomethylidyne)]diphenol) have been synthesized and characterized by elemental analyses, FT‐IR, UV–Vis spectra and X‐ray crystallography. X‐ray crystal structure determinations revealed that each of the Ni(II) complexes 1–4 consists of three Ni(II) atoms, two completely deprotonated (L)2− units, two μ2‐acetate ions and two coordinated solvent molecules (solvents are methanol, n‐propanol, water, N,N‐dimethylformamide and dimethyl sulphoxide, respectively). Although the four complexes 1–4 were synthesized in different solvents, it is worthwhile that the Ni(II) atoms in the four complexes 1–4 adopt hexa–coordinated with slightly distorted octahedral coordination geometries, and the ratios of the ligand H2L to Ni(II) atoms are all 2: 3. The complexes 1–4 possess self‐assembled infinite 1D, 3D, 1D and 2D supramolecular structures via the intermolecular hydrogen bonds, respectively. In addition, fluorescence behaviors were investigated in the complexes 1–4.
Development of stable and active PVA‐PSSA/SA‐PVA catalytic composite membrane for esterification enhancement
Authors: Han Shang , Li Yuewen , Bai Shutong , Zhang Li , Li Weixing , Xing Weihong 
Published: April 2018

ABSTRACTAn active and stable catalytic composite membrane (CCM), poly(vinyl alcohol)–poly(styrene sulfonic acid)/sodium alginate–poly(vinyl alcohol) (PVA‐PSSA/SA‐PVA), was prepared to enhance the esterification of ethanol and propionic acid. The morphologies and crystal structures of the CCMs were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and X‐ray diffraction. The effects of catalytic layer thickness, mass ratio of PVA to PSSA, concentration of catalytic layer solution, ratio of reaction volume to membrane area, and molar ratio of propionic acid to ethanol were discussed. The pervaporation results showed that the flux of CCM increased from 118 to 320 g m−2 h−1 compared with the SA‐PVA membrane because of the close affinity and low resistance of PSSA to water. After crosslinking with 3‐aminopropylmethyldiethoxysilane, the CCMs had good catalytic activities. The acid conversion reached 92.8% at 75 °C in 12 h, and the stabilization of the CCM was greatly improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46514.
Nanocomposite materials based on zinc sulfide nanoparticles reinforced chlorinated styrene butadiene rubber
Authors: Jasna V. C. , Anilkumar T. , Ramesan M. T. 
Published: April 2018

ABSTRACTThe effect of zinc sulfide (ZnS) nanoparticles in chlorinated styrene‐butadiene rubber (Cl‐SBR) was analyzed by X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM), Differential Scanning Calorimetry, and impedance analyzer. The cure time, mechanical properties, and solvent transport of petroleum fuels through the Cl‐SBR/ZnS nanocomposites at different temperatures were evaluated. XRD and SEM studies showed that ZnS nanoparticles were well‐placed in the polymeric structure of Cl‐SBR. The increased glass transition temperature of the composite with the loading of nanoparticles indicated the increased molecular rigidity. Rheometric torque, alternating current conductivity, dielectric property, tensile strength, tear resistance, modulus, hardness, abrasion resistance, heat build‐up, and compression set were increased with the loading of nanoparticles, however, cure and scorch time, elongation at break, and resilience were reduced with the loading of nanoparticles. The diffusion results have been explained in terms of the size of liquid molecules and the diffusion mechanism was found to follow the anomalous trend. The activation energy for diffusion, sorption and permeation process was evaluated. These activation energy parameters were increased with the size of the penetrant molecules and also with the loading of nanoparticles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46538.