bluuebunny/crossref_metadata_2025 huggingface dataset:
Stable Oxindolyl‐Based Analogues of Chichibabin's and Müller's Hydrocarbons
Authors: Wang Jian , Xu Xingdong , Phan Hoa , Herng Tun Seng , Gopalakrishna Tullimilli Y. , Li Guangwu , Ding Jun , Wu Jishan
Published: September 2017

Chichibabin's and Müller's hydrocarbons are classical open‐shell singlet diradicaloids but they are highly reactive. Herein we report the successful synthesis of their respective stable analogues, OxR‐2 and OxR‐3, based on the newly developed oxindolyl radical. X‐ray crystallographic analysis on OxR‐2 reveals a planar quinoidal backbone similar to Chichibabin's hydrocarbon, in accordance with its small diradical character (y0=11.1 %) and large singlet–triplet gap (ΔES‐T=−10.8 kcal mol−1). Variable‐temperature NMR studies on OxR‐2 disclose a slow cis/trans isomerization process in solution through a diradical transition state, with a moderate energy barrier (ΔG≠298K=15–16 kcal mol−1). OxR‐3 exhibits a much larger diradical character (y0=80.6 %) and a smaller singlet–triplet gap (ΔES‐T=−3.5 kcal mol−1), and thus can be easily populated to paramagnetic triplet diradical. Our studies provide a new type of stable carbon‐centered monoradical and diradicaloid.
Gold(I)‐Catalyzed Synthesis of Indenes and Cyclopentadienes: Access to (±)‐Laurokamurene B and the Skeletons of the Cycloaurenones and Dysiherbols
Authors: Yin Xiang , Mato Mauro , Echavarren Antonio M.
Published: September 2017

The formal (3+2) cycloaddition between terminal allenes and aryl or styryl gold(I) carbenes generated by a retro‐Buchner reaction of 7‐substituted 1,3,5‐cycloheptatrienes led to indenes and cyclopentadienes, respectively. These cycloaddition processes have been applied to the construction of the carbon skeleton of the cycloaurenones and the dysiherbols as well as to the total synthesis of (±)‐laurokamurene B.
Alkynylation of C(O)–H Bonds Enabled by Photoredox‐Mediated Hydrogen‐Atom Transfer
Authors: Mukherjee Satobhisha , Garza‐Sanchez R. Aleyda , Tlahuext‐Aca Adrian , Glorius Frank
Published: September 2017

The development of new hydrogen‐atom transfer (HAT) strategies within the framework of photoredox catalysis is highly appealing for its power to activate a desired C−H bond in the substrate leading to its selective functionalization. Reported here is the first photoredox‐mediated hydrogen‐atom transfer method for the efficient synthesis of ynones, ynamides, and ynoates with high regio‐ and chemoselectivity by direct functionalization of C
(O)−H bonds. The broad synthetic application of this method has been demonstrated by the selective functionalization of C(O)−H bonds within complex molecular scaffolds.
Hiyama cross‐coupling reaction using Pd(II) nanocatalyst immobilized on the surface of Fe3O4@SiO2
Authors: Karami Kazem , Jamshidian Nasrin , Nikazma Mohammad Mehdi , Hervés Pablo , Shahreza Amir Rezaei , Karami Ali
Published: September 2017

We report a simple process for the synthesis of Fe3O4@SiO2/APTMS (APTMS = 3‐aminopropyltrimethoxysilane) core–shell nanocatalyst support. The new nanocatalyst was prepared by stabilization of Pd(cdha)2 (cdha = bis(2‐chloro‐3,4‐dihydroxyacetophenone)) on the surface of the Fe3O4@SiO2/APTMS support. The structure and composition of this catalyst were characterized using various techniques. An efficient method was developed for the synthesis of a wide variety of biaryl compounds via fluoride‐free Hiyama cross‐coupling reactions of aryl halides with arylsiloxane, with Fe3O4@SiO2/APTMS/Pd(cdha)2 as the catalyst under reaction conditions. This methodology can be performed at 100°C through a simple one‐pot operation using in situ generated palladium nanoparticles. High catalytic activity, quick separation of catalyst from products using an external magnetic field and use of water as green solvent are attributes of this protocol.
Effect of metal complex formation on the antibacterial activity of nitazoxanide: Spectroscopic and density functional theory calculations
Authors: Mansour Ahmed M.
Published: September 2017

In the present work, experimental and theoretical structural studies of two new nitazoxanide (NTZ) complexes, [Co(NTZ)(NO3)2(OH2)] (1) and [Ni(NTZ)(CH3COO)(OH2)]·CH3COO (2) were reported. The susceptibility of Staphylococcus aureus and Escherichia coli towards NTZ and its complexes was assessed. NTZ behaves as a monodentate ligand via the thiazole N atom forming distorted octahedral and tetrahedral complexes with Co(II) and Ni(II) ions, respectively. The d‐d transitions were assigned by the aid of time‐dependent density functional theory calculations. The magnetic susceptibility value of 1 remains unchanged in the temperature range of 298–77K, while that of 2 decreases linearly with the temperature to attain 2.79 μB at 77K. Coordination of NTZ (0.084 μmol ml−1) to Co(II) (1) (0.028 μmol ml−1) and Ni(II) ions (2) (0.079 μmol ml−1) leads to an improvement in the toxicity against S. aureus.
Synthesis, characterization and biological screening studies of mixed ligand complexes using flavonoids as precursors
Authors: Porkodi Jeyaraman , Raman Natarajan
Published: September 2017

Flavonoids are a group of plant phenolics that provide various health benefits through cell signalling pathways and antioxidant effects. In the present study, a new series of mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) were synthesized by incorporating curcumin and quercetin flavonoid precursors. The structural features of the synthesized complexes were explored using elemental analysis, thermogravimetric analysis, UV–visible, infrared, NMR, mass and electron paramagnetic resonance spectral analyses and conductivity measurements. These data support an octahedral geometry of the synthesized complexes. In silico biological activity score for the ligand was predicted using PASS online software. ADMET properties were studied using VLS3D online software. Anti‐inflammatory and antioxidant activities were experimentally validated which prove that theoretical predictions are in agreement with the experimental results. Interestingly the synthesized complexes interact with calf thymus DNA through groove binding mode. Moreover, they have good potential to cleave pUC19 DNA. Minimum inhibitory concentration values of the synthesized complexes reveal that they have better antimicrobial efficacy than the ligands.
Fe3O4@SiO2@propyl‐ANDSA: A new catalyst for the synthesis of tetrazoloquinazolines
Authors: Ghorbani‐Vaghei Ramin , Alavinia Sedigheh , Sarmast Narges
Published: September 2017

In this paper, a mild and green protocol has been developed for the synthesis of quinazoline derivatives. The catalytic activity of 7‐aminonaphthalene‐1,3‐disulfonic acid‐functionalized magnetic Fe3O4 nanoparticles (Fe3O4@SiO2@Propyl–ANDSA) was investigated in the one‐pot synthesis of new derivatives of tetrahydrotetrazolo[1,5‐a]quinazolines and tetrahydrobenzo[h]tetrazolo[5,1‐b]quinazolines from the reaction of aldehydes, 5‐aminotetrazole, and dimedone or 6‐methoxy‐3,4‐dihyronaphtalen‐1(2H)‐one at 100 °C in H2O/EtOH as the solvent. The catalyst was characterized before and after the organic reaction. Fe3O4@SiO2@Propyl–ANDSA showed remarkable advantages in comparison with previous methods. Advantages of the method presented here include easy purification, reusability of the catalyst, green and mild procedure, and synthesis of new derivatives in high yields within short reaction time.
Preparation of magnetically recyclable ZnFe2O4 nanoparticles by easy single‐step co‐precipitation method and their catalytic performance in the synthesis of 2‐aminothiophenes
Authors: Erfaninia N. , Tayebee R. , Foletto E.L. , Amini M.M. , Dusek M. , Zonoz F.M.
Published: September 2017

In this work, a new synthetic route for the preparation of ZnFe2O4 nanoparticles through the chemical co‐precipitation using Fe2+ and Fe3+ ions in an alkaline solution was developed. The synthesized nanoparticles were characterized by XRD, FTIR, SEM, ICP‐MS, DRS, TGA, VSM and elemental analysis. Characterization results confirmed the formation of single ZnFe2O4 phase, with an average particle size of 40 nm and a high saturation magnetization of 34 emu g−1. The prepared material was employed as a catalyst for the synthesis of 2‐aminotiophene derivatives through the Gewald reaction. This thermally and chemically stable nanocatalyst is environmentally benign, economical and reusable which can be easily recovered using an external magnet. Therefore, it appears that this methodology can be simply extended for industrial purposes.
Electrospinning of polycaprolactone nanofibers using H2O as benign additive in polycaprolactone/glacial acetic acid solution
Authors: Li Wenchao , Shi Lei , Zhang Xianglin , Liu Kang , Ullah Ismat , Cheng Penghua
Published: September 2017

Considerable efforts have been devoted to the production of polycaprolactone (PCL) nanofibrous structures by electrospinning. However, some toxic solvents have often been used to achieve bead‐free nanofibers. At present, a benign solvent such as glacial acetic acid (GAC) only leads to beaded or microscale fibers. Therefore a study is done to extend the electrospinnability of the PCL/GAC system by the addition of H2O. The solution properties of conductivity, viscosity, and surface tension were altered by the addition of H2O, especially increasing the conductivity and viscosity. These properties essential to electrospinning could remain stable for 6 h when the H2O content was less than or equal to 9 vol %. Then ultrafine PCL fibers with diameters from 188 to 200 nm, 10 times smaller than when dissolved in pure GAC, were electrospun from solutions of PCL with concentrations in the range of 17 to 20 wt % with H2O content at 9 vol %. Finally, the crystallinity and crystallite size of the resulting fibers were smaller than that of raw PCL pellets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45578.
Poly(lactic acid) formulations with improved toughness by physical blending with thermoplastic starch
Authors: Ferri J.M. , Garcia‐Garcia D. , Carbonell‐Verdu A. , Fenollar O. , Balart R.
Published: September 2017

This work focuses on poly(lactic acid) (PLA) formulations with improved toughness by physical blending with thermoplastic maize starch (TPS) plasticized with aliphatic–aromatic copolyester up to 30 wt %. A noticeable increase in toughness is observed, due to the finely dispersed spherical TPS domains in the PLA matrix. It is worth to note the remarkable increase in the elongation at break that changes from 7% (neat PLA) up to 21.5% for PLA with 30 wt % TPS. The impact‐absorbed energy is markedly improved from the relatively low values of neat PLA (1.6 J m−2) up to more than three times. Although TPS is less thermally stable than PLA due to its plasticizer content, in general, PLA/TPS blends offer good balanced thermal stability. The morphology reveals high immiscibility in PLA/TPS blends, with TPS‐rich domains with an average size of 1 μm, finely dispersed which, in turn, is responsible for the improved toughness. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45751.
Single Microbead‐Anchored Fluorescent Immunoassay (SMFIA): A Facile and Versatile Platform Allowing Simultaneous Detection of Multiple Antigens
Authors: Chen Desheng , Zhang Xiaobo , Zhu Liping , Liu Chenghui , Li Zhengping
Published: September 2017

A new concept of single microbead (MB)‐anchored fluorescent immunoassay (SMFIA) is proposed with greatly improved sensitivity. In the SMFIA, a single MB is manipulated as the reaction carrier so that the target‐tethered fluorescent immunocomplexes will be highly concentrated on one MB. By monitoring the enriched fluorescence signal on the single MB through imaging, highly sensitive target quantification can be realized just by employing the most common sandwich immunoreactions without requirement of further signal amplification routes. The high sensitivity of the SMFIA can fully meet the demand of current medical diagnosis. Furthermore, we have further advanced a fluorescence‐encoding mechanism for the proposed SMFIA which allows the simultaneous detection of multiple antigens in a single reaction. Sharing the distinct advantages of simple operation, high sensitivity and multiplexed detection capability, the SMFIA provides a general platform for the detection of various biomarkers.
Suppression of Arabidopsis flowering by near‐null magnetic field is mediated by auxin
Authors: Xu Chunxiao , Zhang Yuxia , Yu Yang , Li Yue , Wei Shufeng
Published: September 2017

We previously found that flowering of Arabidopsis was suppressed by near‐null magnetic field, which was related to cryptochrome. Auxin plays an important role in Arabidopsis flowering. To test whether auxin is involved in the suppression of Arabidopsis flowering by near‐null magnetic field, we detected auxin level and expressions of auxin transport and signaling genes in wild‐type Arabidopsis plants and cryptochrome double mutant, cry1/cry2, grown in near‐null magnetic field. We found that indole‐3‐acetic acid (IAA) level in roots of wild‐type plants in near‐null magnetic field was significantly increased compared with the local geomagnetic field control, while IAA level in rosettes of 33‐day‐old wild‐type plants in near‐null magnetic field was significantly lower than the control. Expressions of three auxin transporter genes, PIN1, PIN3, and PIN7, in wild‐type plants were upregulated by near‐null magnetic field. Transcript levels of transcriptional repressor genes, IAA1, IAA5, IAA6, IAA16, and IAA19, were significantly higher in wild‐type plants in near‐null magnetic field than in control plants. However, IAA level and expressions of all the detected genes in cry1/cry2 mutants in near‐null magnetic field were similar to controls. Our results suggest that near‐null magnetic field affects the distribution of auxin in Arabidopsis by transcriptional upregulation of auxin transporter genes, and that change in distribution of auxin and increased expressions of transcriptional repressor genes result in delay of flowering in Arabidopsis in near‐null magnetic field, which are mediated by cryptochrome. Bioelectromagnetics. 39:15–24, 2018. © 2017 Wiley Periodicals, Inc.
In situ biosensor for detection miRNA in living cells based on carbon nitride nanosheets with catalytic hairpin assembly amplification
Authors: Liao Xianjiu , Li Liqing , Pan Jianbin , Peng Tingting , Ge Bin , Tang Qianli
Published: September 2017

In this study, an ultrasensitive fluorescence turn‐on assay for in situ sensing of intracellular microRNA (miRNA) was developed utilizing a carbon nitride nanosheet (CNNS) and a catalytic hairpin assembly (CHA). The CHA showed favourable signal amplification for low‐level biomarkers, and CNNS was an excellent candidate as a fluorescence quencher and gene vector. Moreover, the hairpin DNA of CHA could be adsorbed onto the surface of CNNS. An enzyme‐free fluorescence biosensor for ultrasensitive sensing of intracellular miRNA in cells based on CHA and CNNS was designed. When faced with target miRNA, the fluorescence was recovered due to the miRNA, which could trigger cycling of CHA circuits, leading to the production of a marked enhanced fluorescence signal. Compared with traditional methods, the proposed method is convenient, with low cytotoxicity, and high specificity and ultrasensitivity. It has promising potential for detection low‐level biomarkers.
Development of an optical sensor for chlortetracycline detection based on the fluorescence quenching of l‐tryptophan
Authors: Zhang Hui , Chen Hongyun , Pan Shuang , Yang Huan , Yan Jingjing , Hu Xiaoli
Published: September 2017

A simple and selective spectrofluorimetric method for the detection of chlortetracycline (CTC) was studied. In pH 7.4 buffer medium l‐tryptophan (l‐Trp), applied as the fluorescence probe, interacted with CTC resulting in fluorescence quenching of the probe. CTC was detected with maximum excitation and emission wavelengths at λex/λem = 275/350 nm. Notably, quenching of fluorescence intensities was positively proportional to the CTC concentration over the range of 0.65–30 μmol L−1 and the limit of detection was 0.2 μmol L−1. Effect of temperature shown in Stern−Volmer plots, absorption spectra and fluorescence lifetime determination, indicated that fluorescence quenching of l‐Trp by CTC was mainly by static quenching. The proposed study used practical samples analysis satisfactorily.
Double-blind randomized clinical trial of percutaneous endoscopic gastrostomy versus radiologically inserted gastrostomy in children
Authors: Singh R R , Nah S A , Roebuck D J , Eaton S , Pierro A , Curry J I , Barnacle A , Chippington S , Stuart S , Gibson C , Cross K M K , Stanwell J , Yardley I E , Kiely E M , De Coppi P
Published: September 2017

Background

The aim of this RCT was to determine whether radiologically inserted gastrostomy (RIG) in children is associated with more complications than percutaneous endoscopic gastrostomy (PEG).

Methods

Children at a single tertiary children's hospital requiring a primary gastrostomy were randomized to PEG or RIG. Patients were followed by assessors blinded to the insertion method. Complications were recorded, assigned a severity score, and analysed by zero-inflated Poisson regression analysis on an intention-to-treat basis, adjusting for length of follow-up.

Results

Over a 3-year period, 214 children were randomized (PEG, 107; RIG, 107), of whom 100 received PEG and 96 RIG. There was no significant difference in the number of complications between PEG and RIG groups (P = 0·875), or in the complication score: patients undergoing RIG had a 1·04 (95 per cent c.i. 0·89 to 1·21) times higher complication score than those who underwent PEG (P = 0·597). Only age had an independent significant effect on complication score, with older patients having a 0·97 (0·95 to 1·00) times lower complication score per year.

Conclusion

PEG and RIG are both safe methods of gastrostomy insertion with a low rate of major complications. Registration number: NCT01920438 (http://www.clinicaltrials.gov).
Catheter‐related right atrial thrombus in sickle cell disease
Authors: Zhao Chen , Sathya Bharath , Nadal Rios Rosa , Arai Andrew E. , Brofferio Alessandra , Thein Swee Lay , Ruhl A. Parker
Published: September 2017

Key Clinical Message

Catheter‐related right atrial thrombus (CRAT) can occur in patients with sickle cell disease, particularly if additional risk factors for thrombosis are present. Cardiac MRI may differentiate thrombi from other types of atrial masses. Treatment should include anticoagulation and the timing of catheter removal should balance the potential risk of embolization.
Vanadium‐Catalyzed Deoxydehydration of Glycerol Without an External Reductant
Authors: Petersen Allan R. , Nielsen Lasse B. , Dethlefsen Johannes R. , Fristrup Peter
Published: September 2017

A vanadium‐catalysed deoxydehydration (DODH) of neat glycerol has been developed. Cheap and readily available ammonium metavanadate (NH4VO3) affords higher yields of allyl alcohol than the well‐established catalyst methyltrioxorhenium. A study in which deuterium‐labelled glycerol was used was undertaken to further elucidate the dual role of glycerol as both an oxidant and reductant. This study led to the proposal of a metal‐catalysed DODH mechanism for the production of allyl alcohol and a deeper understanding of the formation of the byproducts acrolein and propanal.
Promoting Catalytic Oxygen Activation by Localized Surface Plasmon Resonance: Effect of Visible Light Pre‐treatment and Bimetallic Interactions
Authors: Wong Roong Jien , Tsounis Constantine , Scott Jason , Low Gary K.‐C. , Amal Rose
Published: September 2017

Visible light pre‐treatment has been found to be capable of enhancing the catalytic oxygen activation on AuPt/TiO2 by up to seven times. Visible light pre‐treatment exploits the localized surface plasmon resonance effect of Au to generate free electrons, which are transferred to the Pt active sites. The electron transfer was evident from a change in Pt speciation observed from X‐ray photoelectron spectroscopy, showing the presence of PtO after visible light pre‐treatment. Photoluminescence spectroscopy was used to reveal the bimetallic synergistic enhancement, as indicated by an overall decrease in the charge recombination rate. Further examination revealed that a good bimetallic interaction is necessary to achieve the enhancement by visible light pre‐treatment. Weak bimetallic interaction, such as the occurrence of element segregation in the bimetallic alloy, inhibits electron transfer from the Au to the Pt and increases electron recombination rates, diminishing the degree to which visible light pre‐treatment improves catalytic performance.
Directed Growth of a Bimetallic MOF Membrane and the Derived NiCo Alloy@C/NixCo1‐xO/Ni Foam Composite as an Efficient Electrocatalyst for the Oxygen Evolution Reaction
Authors: Ping Dan , Feng Xiao , Zhang Jun , Geng Jianming , Dong Xinfa
Published: September 2017

Hierarchically structured bimetallic NiCo‐MOF/LDH/Ni foam (NiCo‐MOF/LDH/NF; MOF=metal−organic framework, LDH=layered double hydroxides) composites were successfully fabricated by means of the in situ growth of NiCo‐MOF on the NiCo LDH buffer‐layer‐modified NF surface. After carbonization, the derived NiCo alloy@C/NixCo1‐xO/NF hierarchical nanocomposite showed excellent electrocatalytic activity with respect to the oxygen evolution reaction (OER); specifically, it exhibited a very low overpotential of 300 mV at a current density of 100 mA cm−2. The outstanding OER activity of the composite may be attributed to the open structure of the nanocomposite, the formation of the highly dispersed CoNi alloy, and the synergistic interaction between CoNi@C and NixCo1‐xO. This work introduces a new strategy for constructing advanced hierarchically structured nanocomposites for diverse applications.
Quantitative Analysis of the Self‐Assembly Process of Hexagonal PtII Macrocyclic Complexes: Effect of the Solvent and the Components
Authors: Baba Ayako , Kojima Tatsuo , Hiraoka Shuichi
Published: September 2017

The self‐assembly process of three PtII‐linked hexagonal macrocycles consisting of dinuclear PtII complexes and organic ditopic ligands was investigated in polar and less polar solvents by a recently developed approach: quantitative analysis of the self‐assembly process (QASAP). In polar CD3NO2, for all the three macrocycles, an ML2 complex was the dominant intermediate during self‐assembly, as a result of high positive allosteric cooperativity for the ligand exchange on the PtII centers of the dinuclear PtII complexes. On the other hand, in less polar CD2Cl2, the self‐assembly process was affected by the components. For two of the three macrocycles, the chainlike oligomers that contain fewer metals and ligands than the corresponding macrocycles grew with time and the type of the chainlike intermediates formed correlated with the allostericity of the two binding sites in the organic ditopic ligands. In every case, no long oligomers containing more components than the macrocycles themselves were produced during the self‐assembly even though free rotation around single bonds in the chainlike oligomers allows them to adopt various conformations that do not facilitate the cyclization. This result suggests that electrostatic and/or steric factors besides rigidity of the components make the cyclization advantageous not only thermodynamically but also kinetically.
Rutile TiO2 Mesocrystals as Sulfur Host for High‐Performance Lithium–Sulfur Batteries
Authors: Sun Qingqing , Chen Kaixiang , Liu Yubin , Li Yafeng , Wei Mingdeng
Published: September 2017

Although lithium–sulfur (Li–S) batteries are among the most promising rechargeable batteries in the field of energy‐storage devices, their poor cycling performance restricts their potential applications. Polar materials can improve the cycling stability owing to their inherent strong chemical interaction with polysulfides. Herein, novel rutile TiO2 mesocrystals (RTMs) are employed as the host for sulfur in Li–S batteries; the RTMs display a stable cycling performance with a capacity retention of 64 % and a small average capacity decay rate of 0.12 % per cycle over 300 cycles at 1 C rate. The good electrochemical properties are attributed to the interior ordered nanopores of the RTMs, which can effectively limit the dissolution of polysulfides, and the ultrafine nanowires in RTMs, which shorten the path for lithium‐ion transport effectively.
Pd/C‐Catalyzed Aminocarbonylation of Aryl Iodides with Anthranils in Water Using Mo(CO)6 as the CO Source
Authors: Wang Zechao , Yin Zhiping , Wu Xiao‐Feng
Published: September 2017

A convenient procedure for the synthesis of N‐(2‐carbonylaryl)benzamides has been developed. Through Pd/C‐catalyzed aminocarbonylation of anthranils with various hindered and functionalized aryl iodides, the desired amides were afforded in moderate to good yields. The protocol is advantageous due to the recyclable Pd/C catalyst, safe Mo(CO)6 as the solid CO source, and environmentally benign water as solvent. No inert atmosphere protection is needed.
Quadruple Stimuli‐Responsive Mechanized Silica Nanoparticles: A Promising Multifunctional Nanomaterial for Diverse Applications
Authors: Ding ChenDi , Tong Ling , Fu JiaJun
Published: September 2017

Novel quadruple stimuli‐responsive mechanized silica nanoparticles were constructed by installation of supramolecular nanovalves onto the exterior surface of mesoporous silica nanoparticles. The release of cargo molecules is triggered by acid/Zn2+/alkali/reduction potential stimuli. This has potential application in the development of drug delivery systems or construction of smart anticorrosion coatings.
Hydrogen Chemisorption on Singly Vanadium‐Doped Aluminum Clusters
Authors: Vanbuel Jan , Fernández Eva M. , Ferrari Piero , Gewinner Sandy , Schöllkopf Wieland , Balbás Luis C. , Fielicke André , Janssens Ewald
Published: September 2017

The effect of vanadium doping on the hydrogen adsorption capacity of aluminum clusters (Aln+, n=2–18) is studied experimentally by mass spectrometry and infrared multiple photon dissociation (IRMPD) spectroscopy. We find that vanadium doping enhances the reactivity of the clusters towards hydrogen, albeit in a size‐dependent way. IRMPD spectra, which provide a fingerprint of the hydrogen binding geometry, show that H2 dissociates upon adsorption. Density functional theory (DFT) calculations for the smaller AlnV+ (n=2–8,10) clusters are in good agreement with the observed reactivity pattern and underline the importance of activation barriers in the chemisorption process. Orbital analysis shows that the activation barriers are due to an unfavorable overlap between cluster and hydrogen orbitals.
Development and characterization of pine bark with enhanced capacity for uptaking Cr(III) from aqueous solutions
Authors: Arim Aline L. , Cecílio Daniela F. M. , Quina Margarida J. , Gando‐Ferreira Licínio M.
Published: September 2017

This work aims for the development and characterization of a new biosorbent with enhanced capacity for recovery of Cr(III) from aqueous solutions. The adsorbent was developed by chemical modification of pine bark (Pinus pinaster) (PB). Initially, several chemical agents (HCl, H2SO4, HNO3, H3PO4, citric acid, acetic acid, NaOH) were tested, but the best results were obtained with NaOH. The adsorbent developed was characterized regarding chemical composition and thermal behaviour before and after chemical modification. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM‐EDS) showed the morphology and the most relevant elements on the surface before and after adsorption of Cr(III). Fourier transform infrared spectroscopy (FTIR) revealed the important role of carboxylate groups in Cr(III) uptake. The adsorption process was studied under different conditions, namely for testing the particle size (in the ranges from 0.088 to 0.149 and 0.250 to 0.595 mm). The equilibrium isotherms showed that Cr(III) adsorption is strongly dependent on particle size. According to the Langmuir model, the maximum adsorption capacity of Cr(III) increased from 17.15 to 31.40 mg/g as the particle range decreased. The experimental Cr(III) removal efficiencies as a function of the adsorbent dosage were well predicted by the mass balance equation for the batch adsorption process coupled with the equilibrium isotherm.
A Novel BODIPY‐Based Low‐Band‐Gap Small‐Molecule Acceptor for Efficient Non‐fullerene Polymer Solar Cells
Authors: Liu Wenxu , Yao Jiannian , Zhan Chuanlang
Published: September 2017

We report herein an efficient A1‐C≡C‐A2‐C≡C‐A1 type small‐molecule 4,4'‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐ indacene (BODIPY) acceptor (A1=BODIPY and A2=diketopyrrolopyrrole (DPP)) by following the A‐to‐A excited electron delocalization via the BODIPY meso‐position, the inherent directionality for the excited electron delocalization. The lowest unoccupied molecular orbital (LUMO) delocalizes across over whole the two flanking A1 and the central A2, and the highest occupied molecular orbital (HOMO) localizes dominantly on the ‐C≡C‐DPP‐C≡C‐ segment. The excited electron upon light excitation of the DPP segment delocalizes over both the BODIPY and DPP segments. The acceptor in chloroform shows an unprecedented plateau‐like broad absorption between 550 and 700 nm with a large FWHM value of 195 nm. Upon transition into solid film, the acceptor shows absorption in the whole near ultraviolet‐visible‐near infrared wavelength region (300‐830 nm) with a low band gap of 1.5 eV and a maximum absorptivity of 0.85×105 cm‐1. Introduction of the ethynyl spacer between the A1 and A2 and the close BODIPY‐to‐DPP LUMO energy levels are crucial for the excited π−electron delocalization across over whole the conjugation backbone. A power conversion efficiency of 6.60% was obtained from the ternary non‐fullerene solar cell with PTB7‐Th:p‐DTS(FBTTh2)2 (0.5 : 0.5) as the donor materials, which is the highest value among the non‐fullerene organic solar cells with BODIPY as the electron acceptor material.
Microfluidic Generation of Bioinspired Spindle‐knotted Graphene Microfibers for Oil Absorption
Authors: Wu Ziqian , Wang Jie , Zhao Ze , Yu Yunru , Shang Luoran , Zhao Yuanjin
Published: September 2017

Graphene materials have a demonstrated value in water treatment. Efforts to promote these materials are focused on the generation of functional graphene adsorbents for effectively removing contaminants from water. Here, inspired by the conformation of spider silks, we present a novel graphene microfiber material with spindle‐knotted microstructures by using a microfluidic emulsification and spinning collaborative technology. The size and spacing of the spindle‐knots were highly controllable by adjusting the flow rates of microfluidics during the generation process of the microfibers. The generated microfibers could adsorb oil from a water‐oil mixed environment due to their hydrophobic surface chemistry. Because of the surface energy curvature gradient and the difference in Laplace pressure, the collected oil tended to form droplets and move from joints between the spindle‐knots to the knots. In addition, by encapsulating additional functional elements, such as magnetic nanoparticles, the graphene microfiber with the ability to control and facilitate the collection of oily contaminants can also be achieved. These features greatly prove the promising values of the spindle‐knotted graphene microfibers in the protection of the environment.
An extensible two‐phase high voltage‐boosting converter with automatic current balance
Authors: Hwu K.I. , Jiang W.Z. , Wu P.Y.
Published: September 2017

In this study, an extensible 2‐phase interleaved high step‐up converter with automatic current balance is presented. This converter uses coupled inductors and energy‐transferring capacitors to improve the voltage gain of the traditional 2‐phase interleaved boost converter as well as employs these energy transferring capacitors to do automatic current balance. Furthermore, the voltage gain can be enhanced not only by adjusting the turns ratio but also by increasing the numbers of phases, diodes, and energy‐transferring capacitors. Therefore, it can be used in high input current and high step‐up voltage applications. In this paper, the basic operating principles of the proposed converter are described and analyzed, and finally, its effectiveness is demonstrated by experiment. In addition, the field‐programmable gate array, named EP13T100C8N and manufactured by Altera Co, is used as a control kernel, and an experimental prototype, with input voltage of 12 V, output voltage of 200 V, and rated output power of 200 W, is given to provide the effectiveness of the proposed converter.
Diversity in the emotional modulation of pain perception: An account of individual variability
Authors: McIver T.A. , Kornelsen J. , Stroman P.W.
Published: September 2017

Background

While emotional state has been shown to modulate pain perception, there has been little consideration for the individual variability in this effect, or what factors may contribute to individual‐level differences. The objective of this study was to characterize the variability in emotional modulation of pain in a healthy sample.

Methods

Twenty‐five healthy, adult females participated in a heat pain‐rating task. After calibration of the appropriate temperature for each participant, the pain‐rating task was combined with viewing of positive, neutral, or negative valence images. Participants rated pain intensity and unpleasantness of the painful stimulus.

Results

The magnitude of the effect for emotional modulation of pain was markedly variable across individuals. Some participants exhibited greater pain relief from the positive emotional stimuli while others were more susceptible to pain amplification from the negative emotional stimuli. There were also significant correlations between emotional modulation of pain and specific psychological measures (depression and anxiety).

Conclusion

Overall, inducing a positive emotional state mitigates pain perception, while negative emotional state amplifies it. The magnitudes of these separate pain‐modulating effects, however, vary across individuals, and are associated with individual levels of depressive and anxious feelings, even within a non‐clinical population.

Significance

The opposite effects of valence on pain amplification and modulation revealed in this study are novel. This study shows that emotional modulation of pain varies markedly across individuals and is related to psychological factors including depression and anxiety. Examining this link in healthy individuals may inform our understanding of the comorbidity between pain and depression/anxiety.
Facile Synthesis of Cuprous Oxide/Gold Nanocomposites for Nonenzymatic Amperometric Sensing of Hydrogen Peroxide
Authors: Bai Hongyan , Zhang Liqiu , Shen Hongxia , Liu Lichun
Published: September 2017

In this work, a facile preparation method of cuprous oxide/gold (Cu2O/Au) nanocomposite was successfully developed. The process consisted of one‐pot co‐reduction of HAuCl4 and CuSO4 using ascorbic acid (AA) as a reducing agent at room temperature under magnetic stirring. The structures and compositions of the as‐prepared products were characterized by SEM, EDS, and XRD. Cyclic voltammetry and chronopotentiometry studies revealed that the as‐prepared cubic Cu2O/Au nanocomposites showed enhanced performance towards the non‐enzymatic catalytic reduction of hydrogen peroxide (H2O2) when compared to single‐component Cu2O nanocubes. The linear range of H2O2 determination spanned over 4 orders of magnitude (1 μM∼16.7 mM) and the detection limit was low as 0.45 μM (S/N=3). The enhanced performance of cubic Cu2O/Au was attributed to: i) the synergistic effect between Cu2O and Au, ii) the increase in surface area induced by the reduced size of the nanocubes, and iii) the improved electrical conductivity due to the presence of Au in the particles. Overall, the cubic Cu2O/Au nanocomposites prepared by the proposed method hold great promise for future practical use in H2O2 detection.
Electrochemistry and Spectroelectrochemistry of the Pu (III/IV) and (IV/VI) Couples in Nitric Acid Systems
Authors: Lines Amanda M. , Adami Susan R. , Casella Amanda J. , Sinkov Sergey I. , Lumetta Gregg J. , Bryan Samuel A.
Published: September 2017

The solution chemistry of Pu in nitric acid is explored via electrochemistry and spectroelectrochemistry. By utilizing and comparing these techniques, an improved understanding of Pu behavior and its dependence on nitric acid concentration can be achieved. Here the Pu (III/IV) couple is characterized using cyclic voltammetry, square wave voltammetry, and a spectroelectrochemical Nernst step. Results indicate the formal reduction potential of the couple shifts negative with increasing acid concentration and reversible electrochemistry is no longer attainable above 6 M HNO3. Spectroelectrochemistry is also used to explore the irreversible oxidation of Pu(IV) to Pu(VI) and shine light on the mechanism and acid dependence of the redox reaction.
Response surface methodology for optimization of simultaneous Cr (VI) and as (V) removal from contaminated water by nanofiltration process
Authors: Mojarrad Mojtaba , Noroozi Amin , Zeinivand Ahmad , Kazemzadeh Pouya
Published: September 2017

This article is carried out to investigate the optimal operating condition for nanofiltration (NF) process for the simultaneous removal of chrome (VI) and arsenic (V) ions from contaminated water in which effects of various operating conditions, for example, Cr concentration (0.05, 0.5, 5), As concentration (0.01, 0.1, 1), pH (5, 7, 9), and recovery rate (40, 60, 80%), are investigated. The design of experiments is carried out using response surface method (Box‐Behnken design). The results show that by increasing pH and decreasing recovery rate, the removal rate of chrome and arsenic ions increase. With an increase in chrome and arsenic concentration, arsenic removal efficiency increases, whereas, the chrome removal efficiency decreases to 65.5%. The pH is the main parameter influencing the removal rate. There is an adequate agreement between real data and that obtained from the models (R2 was found to be 0.992 and 0.962, for Cr (VI) and As (V) rejection, respectively). The optimum levels of a chrome concentration of 0.545 mg/L, pH of 9, arsenic concentration of 0.172 mg/L and recovery rate of 42% is applied in predicting the Arsenic and chrome removal efficiency of 99.1% and 83.8%, respectively. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 434–443, 2018
Dependency of the combustion behavior of energy grass and three other types of biomass upon lignocellulosic composition
Authors: Ma Ying , Guan Yanjun , Zhang Kai , Xu Gang , Yang Yongping , Stevenson Paul
Published: September 2017

The combustion characteristics of four kinds of biomass fuels (energy grass, sawdust, corn cob, and walnut shell) are investigated in this article. All the samples are heated from room temperature to 800°C at multiple heating rates of 10, 20, and 30°C/min. The effect of hemicellulose, cellulose, and lignin components on the pyrolysis and combustion processes of energy grass is explored by comparison to those of the other three types of biomass. The hemicellulose and cellulose content of samples could improve the devolatilization performance during biomass combustion. Furthermore, the comprehensive combustion index suggested herein indicates that the combustion performance of energy grass or walnut shell is limited by their high ash content or their low ratio of cellulose to lignin. Kinetic parameters are obtained by combining the isoconversional method (OFW and KAS models) and the method of master‐plots. The apparent activation energy of the devolatilization stage is higher than that of the char oxidization stage, which is mainly influenced by the lignocellulosic composition. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 815–823, 2018
Exploring citizens' support for policy tools at the food, energy, water nexus
Authors: Bullock Justin B. , Bowman Ann O'M.
Published: September 2017

The food, energy, and water (FEW) nexus is attracting the attention of scholars throughout the fields of engineering, biological sciences, and public policy, among others. However, one important piece missing from the research is an understanding of the types of FEW‐related policies citizens support and the factors that drive public support for those policies. As reported in this article, data from a nationally representative survey of the adult U.S. population show that the public's support for different policy tools varies. To understand more about the public's preferences, we use a series of analytic techniques including factor analysis and factor score regressions to test possible explanations for these preferences. We find that citizens’ knowledge about FEW nexus issues increases their support of policies for managing food, energy, water resources; broad concern for the environment also increases support. The public's preferences are also influenced by political ideology, political party identification, and education. These results contribute to an understanding of the public's potential willingness to embrace the role government can play in addressing FEW nexus issues. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 148–154, 2018
Alternative Paths to Diversity: Exploring and Implementing Effective College Admissions Policies
Authors: Orfield Gary
Published: September 2017

Report Number: ETS RR‐17–40
Fuzzification supported spectrum decision framework for cognitive radio networks
Authors: Akhtar A. N. , Ghafoor A. , Rashdi A. , Arif F.
Published: September 2017

Efficient decision support framework and swift occupation of the available licensed spectrum slot by secondary users (SUs) are the challenging issues in cognitive radio networks. An SU has to sense multiple target frequency spectrum slots in the shortest possible time before deciding to select and occupy the best idle slot for its transmission. A spectrum decision framework for the SUs in cognitive radio networks based on fuzzy logic is proposed. The activity time, possession, and quality of service of the spectrum slot lead to the decision of occupying the available spectrum slot(s). The proposed decision framework ensures that the SU's transmission in the particular spectrum slot does not cause any interference with the licensed user of the slot. The proposed method yields enhanced throughput as compared with the existing channel assignment schemes.
The impact of the system state on energy‐efficient transmission of multiple users' flows on the uplink
Authors: Sagkriotis Stavros E. , Roumeliotis Anargyros J. , Papafragkakis Apostolos Z. , Panagopoulos Athanasios D.
Published: September 2017

This work investigates an energy‐efficient link transmission adapted by the system state, ie, the instantaneous total number of a dynamically varying setting of mobile terminals that arrive as independent elastic flows at the Session Layer and are served by Round‐Robin discipline on the uplink. We focus on realistic scenarios of classes of mobile terminals with different constant power profiles and different radio conditions. The analysis shows that state‐dependent link adaptation significantly improves energy efficiency on the long term in comparison to state‐oblivious energy‐efficient link adaptation schemes that have been thoroughly investigated in the literature, offering, at the same time, substantially lower mean latency for transferring files on the uplink. The reason for this important improvement in performance is that the probability of an empty system pool increases faster with the arrival rate under the state‐dependent transmission. Therefore, an active user waiting to be served sees with higher probability no other customers in the queue.
Distributed power control in crowdsensing‐based femtocell networks with QoS provisioning
Authors: Liu Zhixin , Gao Lu , Liu Yang , Ma Kai
Published: September 2017

We consider mobile crowdsensing campaigns that are practiced in the emerging data collection in femtocell networks, which are effective in improving the capacity and coverage of communication users. One of the challenging issues is how to allocate the transmission power and reduce the cross‐tier and co‐tier interferences among users. This paper proposes a Stackelberg game to characterize the actions of macrocell and femtocell users. In the game, the macrocell user is seen as the leader, whereas the femtocell users are seen as the followers. For the macrocell, it aims at maximizing the leader's profit with the constraint of the maximum tolerable interference. The femtocell users attempt to maximize the followers' profit in the network system with consideration of performance guarantee in the aspects of packet delivery rate and time delay, which are modeled as probability constraints. Spectrum sharing is assumed among the macrocell and femtocells. The uncertain channel state information is considered in the formulated problem, and the probability threshold method is utilized to convert the uncertain constraints into tractable ones. Furthermore, a power control and price bargaining algorithm is derived to get the practical operation. Finally, numerical results validate the performances of the proposed scheme in the aspects of convergence, utility of uses, and power consumption.
Influence on the oil‐gas accumulation potential of the laminated algal micritic dolomite in Jixian system from Mesozoic magmatic activities at the south‐western margin of the Ordos Basin, China
Authors: Liu Futian , Li Rongxi , Zhao Bangsheng , Cheng Jinghua , Li Delu , Wu Xiaoli , Li Sanzhong
Published: September 2017

The Mesoproterozoic Jixian System is widely distributed at the south‐western margin of the Ordos Basin. It is mainly dominated by siliceous laminated algal micritic dolomite that is a set of potential carbonate source rocks. The magmatic activities at the south‐western margin of the Ordos Basin were frequent and intensive, and the Tongcheng intrusion exposed in this area has an intrusive contact relationship with the Jixian System. This paper uses geochemical methods to study the influence of magmatism to lithology, physical properties, hydrocarbon generating property, and geochemistry of the Jixian System. Analysis data reveal that, with the increasing distance to the intrusion, the porosity, permeability, and content of dolomite, trace elements, and rare earth elements in surrounding rock decrease while the density and silica content increase gradually. In addition, the parameters have a weakening trend about adsorbed hydrocarbon (S1), pyrolysis hydrocarbon (S2), hydrocarbon generating potential (S1 + S2), and pyrolysis peak temperature (Tmax). The results suggest that the magmatic hydrothermalism and the thermal effect of magmatic intrusion changed the physical and geochemical characteristics of the surrounding rock and promoted the hydrocarbon generation of organic matter. However, these characteristics reflect that the magmatic activities only have a relatively small effect on the laminated algal micritic dolomite in Jixian System without a destructive effect at the south‐western margin of the Ordos Basin. The petroleum potential of the Jixian System is worthy to be further explored.