bluuebunny/crossref_metadata_2025 huggingface dataset:
PhP=CPh2 and Related Phosphaalkenes: A Solution Equilibrium between a Phosphaalkene and a 1,2‐Diphosphetane
Authors: Wang Shuai , Samedov Kerim , Serin Spencer C. , Gates Derek P.
Published: August 2016

The synthesis of phosphaalkenes, ArP=C(R)Ph (1, a: Ar = Ph, R = Ph; b: Ar = o‐Tol, R = Ph; c: Ar = Mes, R = H), bearing sterically less hindered substituents is reported. Phosphaalkenes 1a–b were prepared by treating Ph2C=O with ArP(Li)SiMe3, whereas 1c was accessed from the AlCl3‐mediated reaction of ArP(SiMe3)2 and PhC(O)H. Both 1a and 1b dimerize to afford their respective 1,2‐diphosphetanes (2a and 2b). Compound 2a was characterized by X‐ray crystallography. Dissolution of pure 2a in THF resulted in a temperature dependent equilibrium with monomer 1a (ΔHo = –94.6 ± 14.6 kJ mol–1; ΔSo = –284 ± 48 J mol–1 K–1). Although monomer E/Z‐1c was identified in solution by its characteristic downfield 31P NMR chemical shift (δ = 247.1, 231.5), it was accompanied by the formation of what we believe are oligomers (δ = –25 to 10 ppm, br.). Attempts to trap phosphaalkenes 1a and 1b by treatment with W(CO)5(MeCN) afforded mixtures of complexes W(CO)5(1a–b) (4a–b) and W(CO)4(1a–b)2 (5a–b), the disubstituted species being subjected to X‐ray crystallographic characterization (5a).
In Situ Topotactic Synthesis of Monodispersed Hierarchically Nanostructured Yttrium‐Based Microspindles from a Mesocrystal Precursor
Authors: Zhuang Jianle , Yang Xianfeng , Lei Bingfu , Zhang Haoran , Wu Mingmei , Liu Yingliang
Published: August 2016

Monodispersed hierarchically nanostructured yttrium‐based materials including Y(OH)3, Y6O5F8, and H‐NaYF4 were successfully synthesized from the same mesocrystal Y(OH)xF3–x precursor. It was found that there was a close crystallographic relationship between the precursor and the final products and all of the processes underwent an in situ topotactic transformation.
Photoactivated Functionizable Tetracarbonyl(phenylpyridine)manganese(I) Complexes as CO‐Releasing Molecules: A Direct Suzuki–Miyaura Cross‐Coupling on a Thermally Stable CO‐RM
Authors: Ward Jonathan S. , Bray Joshua T. W. , Aucott Benjamin J. , Wagner Conrad , Pridmore Natalie E. , Whitwood Adrian C. , Moir James W. B. , Lynam Jason M. , Fairlamb Ian J. S.
Published: August 2016

A new class of carbon monoxide‐releasing molecules (CO‐RMs) are reported based on a previously known tetracarbonyl phenylpyridine manganese(I) motif. A pre‐functionalized CO‐RM undergoes a direct Pd‐catalysed Suzuki–Miyaura cross‐coupling with phenylboronic acid to give a π‐extended three‐ring CO‐RM. Cross‐coupling conditions were modified to allow coupling of a morpholine‐containing boronic acid on to a CO‐RM, introducing drug‐like functionality. An LED system was used to facilitate controlled CO‐release. Irradiation using an LED (400 nm or 365 nm) gives rise to faster CO‐release, with lower overall input power than traditional use of a TLC lamp (365 nm), as measured by an assay based on the conversion of deoxymyoglobin to carbonmonoxymyoglobin.
A Ferrocene‐Based Phosphane/Borane Frustrated Lewis Pair for Asymmetric Imine Reduction
Authors: Ye Ke‐Yin , Wang Xiaowu , Daniliuc Constantin G. , Kehr Gerald , Erker Gerhard
Published: August 2016

The α‐phosphanylferrocenecarbaldehyde (pS)‐1 was converted into the β‐styryl derivative (pS)‐4 by Wittig–Horner olefination. Subsequent hydroboration with Piers' borane [HB(C6F5)2] followed by H2 splitting and crystallization gave the phosphonium/hydridoborate product (pS,R)‐5, which was used as a frustrated Lewis pair catalyst for the asymmetric hydrogenation of a series of imines (up to 69 % ee).
Structure and Antiferromagnetism of Trinuclear Heterometallic Strings Containing MnII–MII–MnII Frameworks (M = Ni, Pd, Pt)
Authors: Yu Li‐Chung , Lee Gene‐Hsiang , Sigrist Marc , Lin Tien‐Sung , Peng Shie‐Ming
Published: August 2016

The syntheses, crystal structures, and magnetic properties of three trinuclear, symmetric, heterometal string complexes stabilized by four dipyridylamide (dpa) ligands were explored. MnNiMn(dpa)4Cl2 (1), MnPdMn(dpa)4Cl2 (2), and MnPtMn(dpa)4Cl2 (3) were found to exhibit an approximate D4 symmetry and a linear metal framework helically wrapped by four syn–syn‐type ligands. The center metal ions bond with the amide part of dpa– in a square‐planar environment, and the outer Mn ions bond with Cl– and the pyridyl part of dpa– in a square‐pyramidal environment. The magnetic susceptibilities of these three compounds showed antiferromagnetic interactions (2J = –13.7 cm–1 for 1, –29.7 cm–1 for 2, and –66.2 cm–1 for 3 in the Heisenberg exchange framework) between the MnII magnetic centers. The value of 2J increased with increasing atomic number of the central metal ion. The antiferromagnetic properties were further confirmed by electron paramagnetic resonance spectroscopy studies in variable‐temperature measurements.
Zinc Chloride Complexes with Aliphatic and Aromatic Guanidine Hybrid Ligands and Their Activity in the Ring‐Opening Polymerisation of d,l‐Lactide
Authors: Metz Angela , Plothe Ramona , Glowacki Britta , Koszalkowski Andreas , Scheckenbach Michael , Beringer Andreas , Rösener Thomas , Michaelis de Vasconcellos Janna , Haase Roxana , Flörke Ulrich , Hoffmann Alexander , Herres‐Pawlis Sonja
Published: August 2016

The synthesis of the new hybrid guanidine ligands DMEGdmap, DMEGdeae, TMGdmab, DMEGdmab, TMGdeab and DMEGdeab is reported. These ligands were combined with zinc chloride, and the six obtained new complexes were structurally characterised by X‐ray crystallography and NMR spectroscopy. Further six new zinc chloride complexes were obtained from the hybrid guanidine ligands TMGdmae, DMEGdmae, TMGdeae, TMGdmap, TMGdeap and TEGdeap. Each of the twelve complexes possesses a tetrahedral coordination geometry. The donor situation between guanidine and amine donors was evaluated by use of density functional theory. These complexes show robust activity in the melt polymerisation of technical unsublimed lactide. For selected complexes kinetic polymerisation experiments were performed; these showed first‐order behavior. The end‐group was established by NMR spectroscopy.
Dye‐Sensitized Solar Hydrogen Production: The Emerging Role of Metal‐Free Organic Sensitizers
Authors: Cecconi Bianca , Manfredi Norberto , Montini Tiziano , Fornasiero Paolo , Abbotto Alessandro
Published: August 2016

The production of hydrogen from sunlight and water is finding an increasingly important role in the production of clean fuels from sustainable and abundant energy sources. In this process, commonly referred to as artificial photosynthesis, the role of the dye sensitizer is critical for optimizing the harvesting of visible light and triggering the reduction reaction at the catalytic active site. In recent decades organometallic sensitizers have mainly been studied, often requiring the use of scarce and, in some cases, toxic elements. This microreview describes the state of the art in the use of metal‐free organic sensitizers, highlighting advantages over their organometallic counterparts. The main design and synthetic strategies, specific properties, and device performances are presented. Thanks to recent advances and lower manufacturing costs, organic sensitizers seem set to be of increasing importance for next‐generation clean fuels.
Two T‐Shaped Donor–Acceptor Small Molecules Based on 4,9‐Di(thiophen‐2‐yl)naphtho[2,3‐b]thiophene for Solution‐Processed Organic Solar Cells
Authors: Tan Hua , Peng Wenhong , Liu Hongjian , Luo Yuhong , Chen Yu , Duan Linrui , Yu Junting , Zhang Youming , Zhang Jun , Wang Yafei , Yang Renqiang , Zhu Weiguo
Published: August 2016

Two novel T‐shaped π‐conjugated small molecules of DTNT‐3DPP and DTNT(DPP‐PN)3 with 4,9‐di(thiophen‐2‐yl)naphtho[2,3‐b]thiophene (DTNT) as the donor core and diketopyrrolopyrrole (DPP) as acceptor arms, in the latter case incorporating phenanthrene (PN) units, have been designed and synthesized. The effects of the central core and terminal units on the optical, thermal, electrochemical, and photovoltaic properties have been investigated. It was found that DTNT‐3DPP and DTNT(DPP‐PN)3 exhibit better light‐harvesting and charge‐transport properties than triphenylamine (TPA)‐based star‐shaped molecules. DTNT‐3DPP and DTNT(DPP‐PN)3 were used as donor materials and methyl [6,6]‐phenyl‐C71‐butyrate (PC71BM) as the acceptor for the fabrication of solution‐processed bulk heterojunction (BHJ) solar cells. The power conversion efficiencies (PCEs) of solar cells based on DTNT‐3DPP and DTNT(DPP‐PN)3 are 3.47 and 3.69 %, respectively. These PCEs are higher than those of the corresponding TPA‐based solar cells (1.91 and 3.67 %). Our work indicates that the planar DTNT unit can improve the photovoltaic properties of organic small molecules relative to those of the TPA unit.
Biomimetic Synthesis of Urukthapelstatin A by Aza‐Wittig Ring Contraction
Authors: Schwenk Sebastian , Ronco Cyril , Oberheide Ansgar , Arndt Hans‐Dieter
Published: August 2016

Marine bacteria produce highly cytotoxic polyheterocyclic cyclopeptide natural products by ribosomal peptide biosynthesis. Among them, urukthapelstatin A features a chain of five 2,4′‐connected azole rings within a cyclo‐octapeptide framework. We report a novel synthesis design that uses only α‐amino acids as starting materials that leads to an efficient and stereoselective total synthesis of urukthapelstatin A. Kinetically favored macro‐thiolactonization and high‐yielding aza‐Wittig heterocyclization to contract the macrocycle were crucial for success. These investigations additionally uncovered the unsuspected configurational lability of the embedded enamide substructure in solution.
Cell‐penetrating peptide–labelled smart polymers for enhanced gene delivery
Authors: Zhang Bingyang , Zhang Hu , Dai Sheng , Bi Jingxiu
Published: August 2016

Highly efficient gene delivery vehicles are pursued to progress gene therapy. In this study, we developed the cell‐penetrating peptide‐labelled and degradable gene carriers for efficient external gene transfection. The cationic carriers were prepared by coupling low‐molecular‐weight polyethylenimine (PEI800) with 4ʹ4‐dithiodibutyric acid (DA), and HIV‐1 Trans‐Activator of Transcription (TAT) was conjugated to the carriers as a penetrating peptide. The resulted PEI‐DA‐TAT was able to condense plasmid DNA (pDNA) into a complex with a hydrodynamic size of around 150 nm under a neutral condition. PEI‐DA‐TAT showed negligible cytotoxicity to both Hela and HEK 293 cells with the cell viability of more than 80% beyond the carrier concentration of 50 μg/mL. This new carrier displayed better performance in regard to DNA transfection efficiency in comparison with the carriers of non‐TAT labelled PEI‐DA, commercial PEI25K and low‐molecular‐weight PEI (PEI800). The transfection efficiency of PEI‐DA‐TAT was increased by 8% compared with PEI‐DA and PEI25K. The experimental findings suggested that the developed PEI‐DA‐TAT is a promising carrier for efficient DNA delivery with low cytotoxicity for gene therapy.
Hierarchical Porous Nanostructures of Manganese(III) Oxyhydroxide for All‐Solid‐State Flexible Supercapacitors
Authors: Dai Shuge , Liu Jianlin , Wang Chuanshen , Wang Xue , Xi Yi , Wei Dapeng , Hu Chenguo
Published: August 2016

A three‐dimensional porous MnOOH hierarchical nanostructure grown on flexible carbon fiber fabric is successfully synthesized by a facile hydrothermal method. Monoclinic MnOOH has a crystalline structure layered in the [010] direction. The layered structure facilitates intercalation/deintercalation of Li+ into the interlayer space as well as the adsorption/desorption of Li+ onto the surface of each layer during fast charging/discharging process. This porous hierarchical structure provides many electroactive sites and efficient paths for ion transport. When used as flexible and lightweight electrodes for supercapacitors, the porous MnOOH electrode manifests good electrochemical performance with a high capacitance of 160 F g−1 at a current density of 0.2 mA cm−2, a high energy density of 14 Wh kg−1 at a power density of 162 W kg−1, and great cycling stability. Moreover, the application for the low‐cost and highly flexible supercapacitors in powering light‐emitting diodes (LEDs) highlights its enormous commercial potential in next‐generation energy storage systems.
Tough Ionogel‐in‐Mask Hybrid Gel Electrolytes in Supercapacitors with Durable Pressure and Thermal Tolerances
Authors: Liu Xinhua , Wu Billy , Brandon Nigel , Wang Qigang
Published: August 2016

A primary challenge of gel electrolytes in development of flexible and wearable devices is their weak mechanical performances, including their compressive stress, tensile strength, and puncture resistance. Here we prepare an ionogel‐mask hybrid gel electrolyte, which successfully achieves synergic advantages of the high mechanical strength of the mask substance and the superior electrochemical and thermal characteristics of the ionogel. The fabricated supercapacitor can maintain a relatively stable capacitive performance even under a high pressure of 3236 kPa. Meanwhile, with the good thermal stability of the composite gel electrolyte, the solid‐state supercapacitor can be operated at high temperatures ranging from 25 °C to 200 °C. The ionogel‐mask hybrid gel can be superior tough gel electrolyte for solid‐state flexible supercapacitors with durable advantages in both high temperatures and pressures.
Pretreatment of Graphite Anodes with Lithium Sulfate to Improve the Cycle Performance of Lithium‐Ion Batteries
Authors: Cui Xiaoling , Tang Fengjuan , Li Chunlei , Zhang Yu , Wang Peng , Li Shiyou , Ye Xiushen
Published: August 2016

Graphite electrode surfaces are pretreated by spray‐deposition method with 0.5 mol L−1 Li2SO4 aqueous solution. The physical and electrochemical properties of a solid electrolyte interphase (SEI) film formed on the surface of Li2SO4‐treated graphite electrode are investigated by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and electrochemical measurements. The results show that the SEI film formed, promoted by Li2SO4, is thin, stable, effective, and elastic to accommodate volume changes of graphite electrode during electrochemical cycles. Due to the fact that the Li/mesophase carbon microbeads (MCMB) cell based on Li2SO4‐treated graphite electrode exhibits excellent cycling performance and low interfacial impedance, we can deduce that such modifies have positive implications for lithium‐ion batteries (LIBs), offering the possibility of faster‐charging LIBs and LIBs that are suitable for rate‐demanding applications, such electric vehicles and hybrid electric vehicles.
A Flexible Functional Form Approach To Mortality Modeling: Do We Need Additional Cohort Dummies?
Authors: Li Han , O'hare Colin , Vahid Farshid
Published: August 2016

The increasing amount of attention paid to longevity risk and funding for old age has created the need for precise mortality models and accurate future mortality forecasts. Orthogonal polynomials have been widely used in technical fields and there have also been applications in mortality modeling. In this paper we adopt a flexible functional form approach using two‐dimensional Legendre orthogonal polynomials to fit and forecast mortality rates. Unlike some of the existing mortality models in the literature, the model we propose does not impose any restrictions on the age, time or cohort structure of the data and thus allows for different model designs for different countries' mortality experience. We conduct an empirical study using male mortality data from a range of developed countries and explore the possibility of using age–time effects to capture cohort effects in the underlying mortality data. It is found that, for some countries, cohort dummies still need to be incorporated into the model. Moreover, when comparing the proposed model with well‐known mortality models in the literature, we find that our model provides comparable fitting but with a much smaller number of parameters. Based on 5‐year‐ahead mortality forecasts, it can be concluded that the proposed model improves the overall accuracy of the future mortality projection. Copyright © 2016 John Wiley & Sons, Ltd.
A meta‐analytic framework for detection of genetic interactions
Authors: Liu Yulun , Chen Yong , Scheet Paul
Published: August 2016

With varying, but substantial, proportions of heritability remaining unexplained by summaries of single‐SNP genetic variation, there is a demand for methods that extract maximal information from genetic association studies. One source of variation that is difficult to assess is genetic interactions. A major challenge for naive detection methods is the large number of possible combinations, with a requisite need to correct for multiple testing. Assumptions of large marginal effects, to reduce the search space, may be restrictive and miss higher order interactions with modest marginal effects. In this paper, we propose a new procedure for detecting gene‐by‐gene interactions through heterogeneity in estimated low‐order (e.g., marginal) effect sizes by leveraging population structure, or ancestral differences, among studies in which the same phenotypes were measured. We implement this approach in a meta‐analytic framework, which offers numerous advantages, such as robustness and computational efficiency, and is necessary when data‐sharing limitations restrict joint analysis. We effectively apply a dimension reduction procedure that scales to allow searches for higher order interactions. For comparison to our method, which we term phylogenY‐aware Effect‐size Tests for Interactions (YETI), we adapt an existing method that assumes interacting loci will exhibit strong marginal effects to our meta‐analytic framework. As expected, YETI excels when multiple studies are from highly differentiated populations and maintains its superiority in these conditions even when marginal effects are small. When these conditions are less extreme, the advantage of our method wanes. We assess the Type‐I error and power characteristics of complementary approaches to evaluate their strengths and limitations.
Hydraulic characterization and hydrological behaviour of a pilot permeable pavement in an urban centre, Brazil
Authors: Coutinho Artur Paiva , Lassabatere Laurent , Montenegro Suzana , Antonino Antônio Celso Dantas , Angulo‐Jaramillo Rafael , Cabral Jaime J. S. P.
Published: August 2016

Considering all the alterations on hydrology and water quality that urbanization process brings, permeable pavement (PP) is an alternative to traditional impermeable asphalt and concrete pavement. The goal of the PP and other low impact development devices is to increase infiltration and reduce peak runoff flows. These structures are barely used in Brazil aiming stormwater management, one of the big hydrological issues in cities throughout the country, with increasing urbanization rates. The main objective of this paper is the hydraulic characterization of a PP and the assessment of its hydrological efficiency from the point of view of the infiltration process. The study focuses on a pilot area in a parking lot in an urban area (Recife, Brazil). Soil elements filling the voids between concrete elements were sampled (particle size density, water contents) and tested with water infiltration experiments at several points of the 3 m × 1.5 m surface pilot area. Beerkan Estimation of Soil Transfer parameters algorithm was applied to the infiltration experiment data to obtain the hydraulic characteristics of the soil composing the PP surface layer, the concrete grid pavers (with internal voids filled with natural soil) permeability being neglected. Results show that the soil hydraulic characteristics vary spatially within the pilot area and that the soil samples have different hydraulic behaviours. The hydraulic characteristics derived from Beerkan Estimation of Soil Transfer parameters analysis were implemented into Hydrus code to simulate runoff, infiltration and water balance over a year. The numerical simulation showed the good potential of the PP for rainfall–runoff management, which demonstrates that PP can be used to retrofit existing parking infrastructure and to promote hydrological behaviour close to natural soils. Copyright © 2016 John Wiley & Sons, Ltd.
An approach to analysing plot scale infiltration and runoff responses to rainfall of fluctuating intensity
Authors: Dunkerley David
Published: August 2016

Simulated rainfall of fluctuating intensity was applied to runoff plots on bare dryland soils in order to explore a new method for analysing the non‐steady‐state responses of infiltration and overland flow. The rainfall events all averaged 10 mm/h but included intensity bursts of up to 70 mm/h and lasting 5–15 min, as well as periods of low intensity and intermittency of up to 25 min. Results were compared with traditional steady‐state estimates of infiltrability made under simulated rainfall sustained at a fixed intensity of 10 mm/h. Mean event infiltration rate averaged 13.6% higher under fluctuating intensities, while runoff ratios averaged only 63% of those seen under constant intensity. In order to understand the changing soil infiltrability, up to three affine Horton infiltration equations were fitted to segments of each experiment. All equations had the same final infiltrability fc, but adjusted values for coefficients f0 (initial infiltrability) and Kf (exponential decay constant) were fitted for periods of rainfall that followed significant hiatuses in rainfall, during which subsurface redistribution allowed near‐surface soil suction to recover. According to the fitted Horton equations, soil infiltrability recovered by up 10–24 mm/h during intra‐event rainfall hiatuses of 15 to 20‐min duration, contributing to higher overall event infiltration rates and to reduced runoff ratios. The recovery of infiltrability also reduced the size of runoff peaks following periods of low intensity rainfall, compared with the predictions based on single Horton infiltration equations, and in some cases, no runoff at all was recorded from late intensity peaks. The principal finding of this study is that, using a set of affine equations, the intra‐event time variation of soil infiltrability can be tracked through multiple intensity bursts and hiatuses, despite the lack of steady‐state conditions. Copyright © 2016 John Wiley & Sons, Ltd.
Voltage‐gated sodium channel Nav1.7 promotes gastric cancer progression through MACC1‐mediated upregulation of NHE1
Authors: Xia Jianling , Huang Na , Huang Hongxiang , Sun Li , Dong Shaoting , Su Jinyu , Zhang Jingwen , Wang Lin , Lin Li , Shi Min , Bin Jianping , Liao Yulin , Li Nailin , Liao Wangjun
Published: August 2016

Voltage‐gated sodium channels (VGSCs), which are aberrantly expressed in several human cancers, affect cancer cell behavior; however, their role in gastric cancer (GC) and the link between these channels and tumorigenic signaling remain unclear. The aims of this study were to determine the clinicopathological significance and role of the VGSC Nav1.7 in GC progression and to investigate the associated mechanisms. Here, we report that the SCN9A gene encoding Nav1.7 was the most abundantly expressed VGSC subtype in GC tissue samples and two GC cell lines (BGC‐823 and MKN‐28 cells). SCN9A expression levels were also frequently found to be elevated in GC samples compared to nonmalignant tissues by real‐time PCR. In the 319 GC specimens evaluated by immunohistochemistry, Nav1.7 expression was correlated with prognosis, and transporter Na+/H+ exchanger‐1 (NHE1) and oncoprotein metastasis‐associated in colon cancer‐1 (MACC1) expression. Nav1.7 suppression resulted in reduced voltage‐gated sodium currents, decreased NHE1 expression, increased extracellular pH and decreased intracellular pH, and ultimately, reduced invasion and proliferation rates of GC cells and growth of GC xenografts in nude mice. Nav1.7 inhibition led to reduced MACC1 expression, while MACC1 inhibition resulted in reduced NHE1 expression in vitro and in vivo. Mechanistically, the suppression of Nav1.7 decreased NF‐κB p65 nuclear translocation via p38 activation, thus reducing MACC1 expression. Downregulation of MACC1 decreased c‐Jun phosphorylation and subsequently reduced NHE1 expression, whereas the addition of hepatocyte growth factor (HGF), a c‐Met physiological ligand, reversed the effect. These results indicate that Nav1.7 promotes GC progression through MACC1‐mediated upregulation of NHE1. Therefore, Nav1.7 is a potential prognostic marker and/or therapeutic target for GC.
Fast and accurate fuzzy C‐means algorithm for MR brain image segmentation
Authors: Hemanth D. Jude , Anitha J. , Balas Valentina Emilia
Published: August 2016

Fuzzy theory based intelligent techniques are widely preferred for medical applications because of high accuracy. Among the fuzzy based techniques, Fuzzy C‐Means (FCM) algorithm is popular than the other approaches due to the availability of expert knowledge. But, one of the hidden facts is that the computational complexity of the FCM algorithm is significantly high. Since medical applications need to be time effective, suitable modifications must be made in this algorithm for practical feasibility. In this study, necessary changes are included in the FCM approach to make the approach time effective without compromising the segmentation efficiency. An additional data reduction approach is performed in the conventional FCM to minimize the computational complexity and the convergence rate. A comparative analysis with the conventional FCM algorithm and the proposed Fast and Accurate FCM (FAFCM) is also given to show the superior nature of the proposed approach. These techniques are analyzed in terms of segmentation efficiency and convergence rate. Experimental results show promising results for the proposed approach. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 188–195, 2016
Three‐dimensional macroporous graphene scaffolds for tissue engineering
Authors: Lalwani Gaurav , D'agati Michael , Gopalan Anu , Rao Manisha , Schneller Jessica , Sitharaman Balaji
Published: August 2016

The assembly of carbon nanomaterials into three‐dimensional (3D) porous scaffolds is critical to harness their unique physiochemical properties for tissue engineering and regenerative medicine applications. In this study, we report the fabrication, characterization, and in vitro cytocompatibility of true 3D (>1 mm in all three dimensions), macroscopic (3–8 mm in height and 4–6 mm in diameter), chemically cross‐linked graphene scaffolds prepared via radical initiated thermal cross‐linking of single‐ and multiwalled graphene oxide nanoribbons (SWGONRs and MWGONRs). SWGONR and MWGONR scaffolds possess tunable porosity (∼65‐80%) and interconnected macro‐, micro‐, and nanoscale pores. Human adipose derived stem cells (ADSCs) and murine MC3T3 preosteoblast cells show good cell viability on SWGONR and MWGONR scaffolds after 1, 3, and 5 days comparable to 3D poly(lactic‐co‐glycolic) acid (PLGA) scaffolds. Confocal live‐cell imaging showed that cells were metabolically active and could spread on SWGONR and MWGONR scaffolds. Immunofluorescence imaging showed the presence of focal adhesion protein vinculin and expression of cell proliferation marker Ki‐67 suggesting that cells could attach and proliferate on SWGONR and MWGONR scaffolds. These results indicate that cross‐linked SWGONR and MWGONR scaffolds are cytocompatible and opens‐avenues toward the development of 3D multifunctional graphene scaffolds for tissue engineering applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 73–83, 2017.
Osteogenic capacity of alkali‐free bioactive glasses. In vitro studies
Authors: Brito Ana F. , Antunes Brígida , dos Santos Francisco , Fernandes Hugo R. , Ferreira José M. F.
Published: August 2016

The high alkali content bioactive glasses commonly used to regenerate bone in dental, orthopedic, and maxillofacial surgeries induce some cytotoxicity in surrounding tissues. The present study aims the ability of some alkali‐free bioactive glasses compositions, recently developed by our research group, to stimulate human mesenchymal stem cells (hMSCs) differentiation into osteoblasts in comparison to 45S5 Bioglass®. The obtained results demonstrated that alkali‐free bioactive glasses possess higher stimulating towards differentiation of hMSCs in comparison to the control 45S5 Bioglass®. The von Kossa assay demonstrated that all bioactive glasses studied were able to induce the appearance of calcium deposits even when the cells were cultured in DMEM, proving that these biomaterials per se induce hMSCs cell differentiation. It was also observed that in both cell culture medium used (DMEM, and osteogenesis differentiation medium) alkali‐free bioactive glasses clearly induced the appearance of more calcium deposits than the 45S5 Bioglass®, indicating their greater ability to induce cell differentiation. In summary, these results indicate that alkali‐free bioactive glasses are a safe and valid alternative to 45S5 Bioglass®. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2360–2365, 2017.
Molecular and biochemical evidence on the protective effects of quercetin in isoproterenol‐induced acute myocardial injury in rats
Authors: Kumar Mukesh , Kasala Eshvendar Reddy , Bodduluru Lakshmi Narendra , Kumar Vikas , Lahkar Mangala
Published: August 2016

Cardioprotection represents one of the most important and realistic aspects of preventive therapy today. Quercetin, a naturally occurring dietary flavone, has been studied extensively for its antioxidant properties. The objective of present study is to find out the cardioprotective activity and to explore the underlying mechanisms of quercetin pretreatment (50 mg/kg body weight, orally) for 14 days against isoproterenol (ISO; 100 mg/kg body weight, subcutaneously) induced myocardial infarction in Wistar rats. Cardiac diagnostic markers, oxidative stress, inflammatory cytokines, histopathology along with gene expression analysis of calpain 1 and 2 were carried out in experimental rats. Quercetin pretreatment showed protective effects on heart by significantly attenuating the ISO‐induced oxidative stress, inflammation, protecting heart architecture, and by downregulation of the expression of calpain. Overall, these findings revealed the cardio‐protective potential of quercetin and its mechanism of action against ISO‐induced MI in rats.
Chondrocyte Morphology in Stiff and Soft Agarose Gels and the Influence of Fetal Calf Serum
Authors: Karim Asima , Hall Andrew C.
Published: August 2016

Changes to chondrocyte volume/morphology may have deleterious effects on extracellular matrix (ECM) metabolism potentially leading to cartilage deterioration and osteoarthritis (OA). The factors controlling chondrocyte properties are poorly understood, however, pericellular matrix (PCM) weakening may be involved. We have studied the density, volume, morphology, and clustering of cultured bovine articular chondrocytes within stiff (2% w/v) and soft (0.2% w/v) three‐dimensional agarose gels. Gels with encapsulated chondrocytes were cultured in Dulbecco's Modified Eagle's Medium (DMEM; fetal calf serum (FCS) 1–10%;380 mOsm) for up to 7 days. Chondrocytes were fluorescently labeled after 1, 3, and 7 days with 5‐chloromethylfluorescein‐diacetate (CMFDA) and propidium iodide (PI) or 1,5‐bis{[2‐(di‐methylamino)ethyl]amino}‐4,8‐dihydroxyanthracene‐9,10‐dione (DRAQ5) to identify cytoplasmic space or DNA and imaged by confocal laser scanning microscopy (CLSM). Chondrocyte density, volume, morphology, and clustering were quantified using Volocity™ software. In stiff gels after 7 d with 10% FCS, chondrocyte density remained unaffected and morphology was relatively normal with occasional cytoplasmic processes. However, in soft gels by day 1, chondrocyte volume increased (P = 0.0058) and by day 7, density increased (P = 0.0080), along with the percentage of chondrocytes of abnormal morphology (P < 0.0001) and enhanced clustering (P < 0.05), compared to stiff gels. FCS exacerbated changes to density (P < 0.01), abnormal morphology (P < 0.001) and clustering (P < 0.01) compared to lower concentrations at the same gel strength. Reduced gel stiffness and/or increased FCS concentrations promoted chondrocyte proliferation and clustering, increased cell volume, and stimulated abnormal morphology, producing similar changes to those occurring in OA. The increased penetration of factors in FCS into soft gels may be important in the development of these abnormal chondrocyte properties. J. Cell. Physiol. 232: 1041–1052, 2017. © 2016 Wiley Periodicals, Inc.
Testosterone and Haemosporidian Parasites Along a Tropical Elevational Gradient in Rufous‐Collared Sparrows (Zonotrichia capensis)
Authors: Escallón Camilo , Weinstein Nicole M. , Tallant James A. , Wojtenek Winfried , Rodríguez‐Saltos Carlos A. , Bonaccorso Elisa , Moore Ignacio T.
Published: August 2016

Elevation has been proposed as a dominant ecological variable shaping life history traits and subsequently their underlying hormonal mechanisms. In an earlier meta‐analysis of tropical birds, elevation was positively related to testosterone levels. Furthermore, parasitism by avian haemosporidians should vary with elevation as environmental conditions affect vector abundance, and while testosterone is needed for breeding, it is hypothesized to be immunosuppressive and thus could exacerbate haemosporidian infection. Our objective in this study was to examine the relationships between elevation, testosterone levels, and parasitism by avian haemosporidians. We surveyed breeding male rufous‐collared sparrows (Zonotrichia capensis) across a wide elevational range along the equator. We measured baseline testosterone levels, haemosporidian infection at four elevations spanning the species’ natural range in the Ecuadorian Andes (600, 1500, 2100, 3300 m). Testosterone levels from breeding males were not related to elevation, but there was high intrapopulation variability. Testosterone levels were not related to the probability of parasitism, but our results from one population suggested that the likelihood of being infected by haemosporidian parasites was greater when in breeding condition. In conclusion, even though there is variation in life history strategies among the studied populations, wider divergence in seasonality and life history traits would probably be needed to detect an effect of elevation on testosterone if one exists. Additionally, our results show that variation in testosterone is not related to infection risk of haemosporidians, thus other factors that take a toll on energetic resources, such as reproduction, should be looked at more closely.
Sexually Dimorphic Expression of Foxl2 and Ftz‐F1 in Chinese Giant Salamander Andrias Davidianus
Authors: HU QIAOMU , MENG YAN , TIAN HAIFENG , ZHANG YU , XIAO HANBING
Published: August 2016

Foxl2 and FTZ‐F1 play a crucial role in the regulation of gonad development in fish and mammals, but studies of their function in amphibians are scarce. We isolated the full length of Foxl2 (adFoxl2) and Ftz‐F1 (adFtz‐f1) cDNA from the Chinese giant salamander Andrias davidianus and quantified its expression in various tissues and developing gonads. The adFoxl2 gene encodes 301aa including a conserved forkhead box, and the adFtz‐f1 gene encodes 467aa containing an Ftz‐F1 box. The amino acid sequences showed high homology with other amphibians. adFoxl2 expression was high in ovary, whereas adFtz‐f1 was higher in testis, moderate in pituitary, ovary, and kidney; and low in the remaining tested tissues. Expression of adFoxl2 gradually increased from 1Y to 5Y in ovary, whereas adFtz‐f1 expression gradually decreased in testis. In addition, adFoxl2 and adFtz‐f1 were detected in granulosa cell in ovary and in spermatocytes in testis. The adFoxl2 transcription was inhibited in brain and ovary after treatment with methyltestosterone and with letrozole, whereas adFtz‐f1 expression was upregulated. High‐temperature suppressed the expression of adFxl2 in ovary and enhanced the transcription of adFtz‐f1. These results suggest that adFoxl2 functioned in ovary differentiation, whereas adFtz‐f1 played a role in testis development, which lays a foundation for study of the sex differentiation mechanism in A. davidianus.
Total duration of antimicrobial therapy in veterans hospitalized with uncomplicated pneumonia: Results of a national medication utilization evaluation
Authors: Madaras‐Kelly Karl J. , Burk Muriel , Caplinger Christina , Bohan Jefferson G. , Neuhauser Melinda M. , Goetz Matthew Bidwell , Zhang Rongping , Cunningham Francesca E. ,   for the Pneumonia Duration of Therapy Medication Utilization Evaluation Group
Published: August 2016

OBJECTIVE

Practice guidelines recommend the shortest duration of antimicrobial therapy appropriate to treat uncomplicated pneumonia be prescribed to reduce the emergence of resistant pathogens. A national evaluation was conducted to assess the duration of therapy for pneumonia.

DESIGN

Retrospective medication utilization evaluation.

SETTING

Thirty Veterans Affairs medical centers.

PATIENTS

Inpatients discharged with a diagnosis of pneumonia.

MEASUREMENTS

A manual review of electronic medical records of inpatients discharged with uncomplicated community‐acquired pneumonia (CAP) or healthcare‐associated pneumonia (HCAP) was conducted. Appropriate CAP therapy duration was defined as at least 5 days, and up to 3 additional days beginning the first day the patient achieved clinical stability criteria; the appropriate HCAP therapy duration was defined as 8 days. The duration of antimicrobial therapy for intravenous (IV) and oral (PO) inpatient administration, PO therapy dispensed upon discharge, Clostridium difficile infection (CDI), hospital readmission, and death rates were measured.

RESULTS

Of 3881 pneumonia admissions, 1739 met inclusion criteria (CAP [n = 1195]; HCAP [n = 544]). Overall, 13.9% of patients (CAP [6.9%], HCAP [29.0%]) received therapy duration consistent with guideline recommendations. The median (interquartile range) days of therapy were 4 days (3–6 days), 1 day (0–3 days), and 6 days (4–8 days) for inpatient IV, inpatient PO, and outpatient PO antimicrobials, respectively. CDI was rare but more common in patients who received therapy duration consistent with guidelines. Therapy duration was not associated with the readmission or mortality rate.

CONCLUSIONS

Antimicrobials were commonly prescribed for a longer duration than guidelines recommend. The majority of excessive therapy was completed upon discharge, identifying the need for strategies to curtail unnecessary use postdischarge. Journal of Hospital Medicine 2015;11:832–839. © 2015 Society of Hospital Medicine
Apparent diffusion coefficient measurement in glioma: Influence of region‐of‐interest determination methods on apparent diffusion coefficient values, interobserver variability, time efficiency, and diagnostic ability
Authors: Han Xu , Suo Shiteng , Sun Yawen , Zu Jinyan , Qu Jianxun , Zhou Yan , Chen Zengai , Xu Jianrong
Published: August 2016

Purpose

To compare four methods of region‐of‐interest (ROI) placement for apparent diffusion coefficient (ADC) measurements in distinguishing low‐grade gliomas (LGGs) from high‐grade gliomas (HGGs).

Materials and Methods

Two independent readers measured ADC parameters using four ROI methods (single‐slice [single‐round, five‐round and freehand] and whole‐volume) on 43 patients (20 LGGs, 23 HGGs) who had undergone 3.0 Tesla diffusion‐weighted imaging and time required for each method of ADC measurements was recorded. Intraclass correlation coefficients (ICCs) were used to assess interobserver variability of ADC measurements. Mean and minimum ADC values and time required were compared using paired Student's t‐tests. All ADC parameters (mean/minimum ADC values of three single‐slice methods, mean/minimum/standard deviation/skewness/kurtosis/the10th and 25th percentiles/median/maximum of whole‐volume method) were correlated with tumor grade (low versus high) by unpaired Student's t‐tests. Discriminative ability was determined by receiver operating characteristic curves.

Results

All ADC measurements except minimum, skewness, and kurtosis of whole‐volume ROI differed significantly between LGGs and HGGs (all P < 0.05). Mean ADC value of single‐round ROI had the highest effect size (0.72) and the greatest areas under the curve (0.872). Three single‐slice methods had good to excellent ICCs (0.67–0.89) and the whole‐volume method fair to excellent ICCs (0.32–0.96). Minimum ADC values differed significantly between whole‐volume and single‐round ROI (P = 0.003) and, between whole‐volume and five‐round ROI (P = 0.001). The whole‐volume method took significantly longer than all single‐slice methods (all P < 0.001).

Conclusion

ADC measurements are influenced by ROI determination methods. Whole‐volume histogram analysis did not yield better results than single‐slice methods and took longer. Mean ADC value derived from single‐round ROI is the most optimal parameter for differentiating LGGs from HGGs.

Level of Evidence: 3

J. Magn. Reson. Imaging 2017;45:722–730.
Susceptibility‐weighted imaging using inter‐echo‐variance channel combination for improved contrast at 7 tesla
Authors: Hosseini Zahra , Liu Junmin , Solovey Igor , Menon Ravi S. , Drangova Maria
Published: August 2016

Purpose

To implement and optimize a new approach for susceptibility‐weighted image (SWI) generation from multi‐echo multi‐channel image data and compare its performance against optimized traditional SWI pipelines.

Materials and Methods

Five healthy volunteers were imaged at 7 Tesla. The inter‐echo‐variance (IEV) channel combination, which uses the variance of the local frequency shift at multiple echo times as a weighting factor during channel combination, was used to calculate multi‐echo local phase shift maps. Linear phase masks were combined with the magnitude to generate IEV‐SWI. The performance of the IEV‐SWI pipeline was compared with that of two accepted SWI pipelines–channel combination followed by (i) Homodyne filtering (HPH‐SWI) and (ii) unwrapping and high‐pass filtering (SVD‐SWI). The filtering steps of each pipeline were optimized. Contrast‐to‐noise ratio was used as the comparison metric. Qualitative assessment of artifact and vessel conspicuity was performed and processing time of pipelines was evaluated.

Results

The optimized IEV‐SWI pipeline (σ = 7 mm) resulted in continuous vessel visibility throughout the brain. IEV‐SWI had significantly higher contrast compared with HPH‐SWI and SVD‐SWI (P < 0.001, Friedman nonparametric test). Residual background fields and phase wraps in HPH‐SWI and SVD‐SWI corrupted the vessel signal and/or generated vessel‐mimicking artifact. Optimized implementation of the IEV‐SWI pipeline processed a six‐echo 16‐channel dataset in under 10 min.

Conclusion

IEV‐SWI benefits from channel‐by‐channel processing of phase data and results in high contrast images with an optimal balance between contrast and background noise removal, thereby presenting evidence of importance of the order in which postprocessing techniques are applied for multi‐channel SWI generation.

Level of Evidence: 2

J. Magn. Reson. Imaging 2017;45:1113–1124
Comparison of T2, T1rho, and diffusion metrics in assessment of liver fibrosis in rats
Authors: Zhang Hui , Yang Qihua , Yu Taihui , Chen Xiaodong , Huang Jingwen , Tan Cui , Liang Biling , Guo Hua
Published: August 2016

Purpose

To evaluate the value of T2, T1rho, and diffusion metrics in assessment of liver fibrosis in rats.

Materials and Methods

Liver fibrosis in a rat model (n = 72) was induced by injection of carbon tetrachloride (CCl4) at 3T. T2, T1rho, and diffusion parameters (apparent diffusion coefficient (ADC), Dtrue) via spin echo (SE) diffusion‐weighted imaging (DWI) and stimulated echo acquisition mode (STEAM) DWI with three diffusion times (DT: 80, 106, 186 msec) were obtained in surviving rats with hepatic fibrosis (n = 52) and controls (n = 8). Liver fibrosis stage (F0–F6) was identified based on pathological results using the traditional liver fibrosis staging method for rodents. Nonparametric statistical methods and receiver operating characteristic (ROC) curve analysis were employed to determine the diagnostic accuracy.

Results

Mean T2, T1rho, ADC, and Dtrue with DT = 186 msec correlated with the severity of fibrosis with r = 0.73, 0.83, −0.83, and −0.85 (all P < 0.001), respectively. The average areas under the ROC curve at different stages for T1rho and diffusion parameters (DT = 186 msec) were larger than those of T2 and SE DWI (0.92, 0.92, and 0.92 vs. 0.86, 0.82, and 0.83). The corresponding average sensitivity and specificity for T1rho and diffusion parameters with a long DT were larger (89.35 and 88.90, 88.36 and 89.97, 90.16 and 87.13) than T2 and SE DWI (90.28 and 79.93, 85.30 and 77.64, 78.21 and 82.41). The performances of T1rho and Dtrue (DT = 186 msec) were comparable (average AUC: 0.92 and 0.92).

Conclusion

Among the evaluated sequences, T1rho and STEAM DWI with a long DT may serve as superior imaging biomarkers for assessing liver fibrosis and monitoring disease severity.

Level of Evidence: 1

J. Magn. Reson. Imaging 2017;45:741–750.
Gap filling and homogenization of climatological datasets in the headwater region of the Upper Blue Nile Basin, Ethiopia
Authors: Woldesenbet Tekalegn Ayele , Elagib Nadir Ahmed , Ribbe Lars , Heinrich Jürgen
Published: August 2016

Long‐term time series of climatological data measured at meteorological stations provide one of the most authentic annals of climate in the past. However, there are a host of factors that affect measurements of climate parameters and make the data unsuitable for direct use and analysis. Serial completion and homogenization thus have to be undertaken in order to draw valid conclusions about the climate, or to apply the time series in impact studies. This study reports on gap filling and homogenization results of climatological elements in the headwater region of the Upper Blue Nile Basin from 1980 to 2013. Firstly, approaches for reconstruction of the time series from neighboring stations using different techniques were compared and selected. Neighboring stations were selected based on horizontal distance and coefficient of correlation. Secondly, the reconstructed time series were homogenized using Multiple Analysis of Series for Homogenization (MASH). The results show improved spatial coherence of the final data series. Higher spatial coherence was revealed for maximum temperature than for minimum temperature and rainfall. For rainfall and minimum and maximum temperatures, the coefficient of correlation weighting method outperforms other candidate methods, such as the normal ratio method (NRM), the modified NRM, and the inverse distance weighting method. Rainfall series for half of the stations considered were found to be homogeneous, and thus inhomogeneity corrections were not applied. Inhomogeneity in the remaining stations either underestimates or overestimates annual rainfall series. All stations revealed inhomogeneity in the mean annual maximum and minimum temperature series. These serially complete and homogenized data on rainfall, and minimum and maximum temperatures of the present study can be used for climate change and hydrological studies in the basin.