bluuebunny/crossref_metadata_2025 huggingface dataset:
Set Systems Containing Many Maximal Chains
Authors: JOHNSON J. ROBERT , LEADER IMRE , RUSSELL PAUL A.
Published: October 2014

The purpose of this short problem paper is to raise the following extremal question on set systems: Which set systems of a given size maximise the number of (n + 1)-element chains in the power set $\mathcal{P}$(1,2,. . .,n)? We will show that for each fixed α > 0 there is a family of α2n sets containing (α + o(1))n! such chains, and that this is asymptotically best possible. For smaller set systems we conjecture that a ‘tower of cubes’ construction is extremal. We finish by mentioning briefly a connection to an extremal problem on posets and a variant of our question for the grid graph.
Evaluations of Topological Tutte Polynomials
Authors: ELLIS-MONAGHAN J. , MOFFATT I.
Published: October 2014

We find new properties of the topological transition polynomial of embedded graphs, Q(G). We use these properties to explain the striking similarities between certain evaluations of Bollobás and Riordan's ribbon graph polynomial, R(G), and the topological Penrose polynomial, P(G). The general framework provided by Q(G) also leads to several other combinatorial interpretations these polynomials. In particular, we express P(G), R(G), and the Tutte polynomial, T(G), as sums of chromatic polynomials of graphs derived from G, show that these polynomials count k-valuations of medial graphs, show that R(G) counts edge 3-colourings, and reformulate the Four Colour Theorem in terms of R(G). We conclude with a reduction formula for the transition polynomial of the tensor product of two embedded graphs, showing that it leads to additional relations among these polynomials and to further combinatorial interpretations of P(G) and R(G).
Premchand Plays Chess
Authors: DAVIS DEREK
Published: October 2014

This article contextualises and compares the Urdu and Hindi versions of Premchand's 1924 short story The Chess Players. Close examination of the two texts offers fascinating insight into the challenges of adjustment for Premchand as he moved from his Persian/Urdu literary home-base to the world of modern Hindi that he did so much to help create in the early decades of twentieth-century India.
NON-NEHARI-MANIFOLD METHOD FOR ASYMPTOTICALLY LINEAR SCHRÖDINGER EQUATION
Authors: TANG X. H.
Published: October 2014

We consider the semilinear Schrödinger equation$$\begin{eqnarray}\left\{\begin{array}{@{}l@{}}-\triangle u+V(x)u=f(x,u),\quad x\in \mathbb{R}^{N},\\ u\in H^{1}(\mathbb{R}^{N}),\end{array}\right.\end{eqnarray}$$where$f(x,u)$is asymptotically linear with respect to$u$,$V(x)$is 1-periodic in each of$x_{1},x_{2},\dots ,x_{N}$and$\sup [{\it\sigma}(-\triangle +V)\cap (-\infty ,0)]<0<\inf [{\it\sigma}(-\triangle +V)\cap (0,\infty )]$. We develop a direct approach to find ground state solutions of Nehari–Pankov type for the above problem. The main idea is to find a minimizing Cerami sequence for the energy functional outside the Nehari–Pankov manifold${\mathcal{N}}^{-}$by using the diagonal method.
FORUM: CLOSENESS AND DISTANCE IN THE AGE OF ENLIGHTENMENT INTRODUCTION
Authors: BREWER JOHN , SEBASTIANI SILVIA
Published: October 2014

According to Michel de Certeau, distance is the indispensable prerequisite for historical knowledge and the very characteristic of modern historiography. The historian speaks, in the present, about the absent, the dead, as Certeau labels the past, thus emphasizing the performative dimension of historical writing: “the function of language is to introduce through saying what can no longer be done.” As a consequence, the heterogeneity of two non-communicating temporalities becomes the challenge to be faced: the present of the historian, as a moment du savoir, is radically separated from the past, which exists only as an objet de savoir, the meaning of which can be restored by an operation of distantiation and contextualization. In Evidence de l’histoire: Ce que voient les historiens, François Hartog takes up the question of history writing and what is visible, or more precisely the modalities historians have employed to narrate the past, opening up the way to a reflection on the boundaries between the visible and the invisible: the mechanisms that have contributed to establish these boundaries over time, and the questions that have legitimized the survey of what has been seen or not seen. But, as Mark Phillips points out, it is the very ubiquity of the trope of distance in historical writings that has paradoxically rendered it almost invisible to historians, so that “it has become difficult to distinguish between the concept of historical distance and the idea of history itself.”
TRANSNATIONAL PROJECTS OF EMPIRE IN FRANCE,C.1815–C.1870
Authors: TODD DAVID
Published: October 2014

Rather than renouncing empire after the fall of Napoleon, this essay argues, French liberal thinkers expressed a sustained preference for a strategy based on transnational connections, or what imperial historians describe as informal imperialism. The eulogy of European Christian civilization exemplified by François Guizot's lecture at the Sorbonne in 1828 served not only to legitimize French global ambitions, but also to facilitate cooperation with other European imperial powers, especially Britain, and indigenous collaborators. Liberal enthusiasm for the spread of Western civilization also inspired the emergence of a French version of free-trade imperialism, of which the economist Michel Chevalier proved a consistent advocate. Only when such aspirations were frustrated did liberals reluctantly endorse colonial conquest, on an exceptional basis in Algeria after 1840 and on a global scale after 1870. The allegedly abrupt liberal conversion to empire in the nineteenth century may instead be construed as a tactical shift from informal to formal dominance.
THE TRIUMPH OF THE NEGRO INTELLECTUAL
Authors: BLUM EDWARD J.
Published: October 2014

In the middle of the 1960s, Harold Cruse was angry with his fellow “Negro intellectuals.” “The Negro movement is at an impasse,” he wrote inThe Crisis of the Negro Intellectual, “precisely because it lacks a real functional corps of intellectuals able to confront and deal perceptively with American realities on a level that social conditions demand.” When his book was published in 1967, American race relations seemed to be vectoring toward another nadir. Urban unrest, declining job opportunities for African Americans, the escalating war in Vietnam, and the civil rights movements’ divide over “Black Power” were only parts of the “crisis” Cruse identified. To him, black intellectuals had failed to wrestle with the particularities of racism in the United States and thus had failed to offer meaningful solutions beyond what he deemed to be the dead-end roads of integration and black nationalism.
Selectorate theory, the democratic peace, and public goods provision
Authors: Arena Philip , Nicoletti Nicholas P.
Published: October 2014

We show that without a few peculiar modeling choices that are not justified by the core assumptions of the theory, selectorate theory neither unambiguously predicts the democratic peace nor that leaders of more inclusive regimes will rely upon the provision of public goods to remain in office, though they may be more likely to provide club goods. We illustrate these claims using relatively simple models that incorporate the core assumptions of their theory, while avoiding modeling choices we believe to be less appropriate. We argue for a revised version of selectorate theory, one that continues to emphasize the importance of the size of the winning coalition, yet we believe it provides a more realistic picture of democratic politics.
Growing healthy muscles to optimise metabolic health into adult life
Authors: Bayol S. A. , Bruce C. R. , Wadley G. D.
Published: October 2014

The importance of skeletal muscle for metabolic health and obesity prevention is gradually gaining recognition. As a result, interventions are being developed to increase or maintain muscle mass and metabolic function in adult and elderly populations. These interventions include exercise, hormonal and nutritional therapies. Nonetheless, growing evidence suggests that maternal malnutrition and obesity during pregnancy and lactation impede skeletal muscle development and growth in the offspring, with long-term functional consequences lasting into adult life. Here we review the role of skeletal muscle in health and obesity, providing an insight into how this tissue develops and discuss evidence that maternal obesity affects its development, growth and function into adult life. Such evidence warrants the need to develop early life interventions to optimise skeletal muscle development and growth in the offspring and thereby maximise metabolic health into adult life.
Individual Differences Underlying Punishment Motivation
Authors: Giacomantonio Mauro , Pierro Antonio
Published: October 2014

Two motivations underlying punishment can be distinguished. On the one hand, the retributive motivation prescribes that punishment should be proportional to the moral offense caused. On the other hand, according the utilitarian perspective, punishment should be aimed at protecting society by reducing the likelihood of similar infractions. Previous research did not examine whether individual differences could lead to a preference for one of the two motivations. We propose that high need for closure could be associated with higher utilitarian motivation because of its general concern for group related consequences of violations. In support of our hypothesis, in Study 1 we found that individuals high in need for closure endorsed to a greater extent a zero-tolerance policy rather than a proportional one. Study 2 further showed that closed-minded individuals sought more information related to the utilitarian, rather than the retributive perspective, when judging a violation. Theoretical and practical implications are discussed.
Inhibition of phosphotidylinositol-3 kinase pathway by a novel naphthol derivative of betulinic acid induces cell cycle arrest and apoptosis in cancer cells of different origin
Authors: Majeed R , Hamid A , Sangwan P L , Chinthakindi P K , Koul S , Rayees S , Singh G , Mondhe D M , Mintoo M J , Singh S K , Rath S K , Saxena A K
Published: October 2014

Betulinic acid (BA) is a pentacyclic triterpenoid natural product reported to inhibit cell growth in a variety of cancers. However, the further clinical development of BA got hampered because of poor solubility and pharmacological properties. Interestingly, this molecule offer several hotspots for structural modifications in order to address its associated issues. In our endeavor, we selected C-3 position for the desirable chemical modification in order to improve its cytotoxic and pharmacological potential and prepared a library of different triazoline derivatives of BA. Among them, we previously reported the identification of a potential molecule, that is, 3{1N(5-hydroxy-naphth-1yl)-1H-1,2,3-triazol-4yl}methyloxy betulinic acid (HBA) with significant inhibition of cancer cell growth and their properties. In the present study, we have shown for the first time that HBA decreased the expression of phosphotidylinositol-3 kinase (PI3K) p110α and p85α and caused significant downregulation of pAKT and of NFκB using human leukemia and breast cancer cells as in vitro models. Further it was revealed that PI3K inhibition by HBA induced cell cycle arrest via effects on different cell cycle regulatory proteins that include CDKis cyclins and pGSK3β. Also, this target-specific inhibition was associated with mitochondrial apoptosis as was reflected by the increased expression of mitochondrial bax, downregulated bcl2 and decreased mitochondrial levels of cytochrome c, together with reactive oxygen species generation and decline in mitochondrial membrane potential. The apoptotic effectors such as caspase 8, caspase 9 and caspase 3 were found to be upregulated besides DNA repair-associated enzyme, that is, PARP cleavage caused cancer cell death. Pharmacodynamic evaluation revealed that both HBA and BA were safe upto the dose of 2000 mg/kg body weight and with acceptable pharmacodynamic parameters. The in vitro data corroborated with in vivo anticancer activity wherein Ehrlich solid tumor showed that HBA as a more potent agent than BA without any body weight loss and mortality.
Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils
Authors: Wang Baozhan , Zhao Jun , Guo Zhiying , Ma Jing , Xu Hua , Jia Zhongjun
Published: October 2014

Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3−-N g−1 dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in 13C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of 13CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the 13C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The 13C-NOB was overwhelmingly dominated by Nitrospira rather than Nitrobacter. A significant correlation was observed between the active AOA/AOB ratio and the soil oxidation capacity, implying a greater advantage of AOA over AOB under microaerophilic conditions. These results suggest the important roles of soil physiochemical properties in determining the activities of ammonia oxidizers and nitrite oxidizers.
Visualized effect of oxidation on magnetic recording fidelity in pseudo-single-domain magnetite particles
Authors: Almeida Trevor P. , Kasama Takeshi , Muxworthy Adrian R. , Williams Wyn , Nagy Lesleis , Hansen Thomas W. , Brown Paul D. , Dunin-Borkowski Rafal E.
Published: October 2014

Magnetite (Fe3O4) is an important magnetic mineral to Earth scientists, as it carries the dominant magnetic signature in rocks, and the understanding of its magnetic recording fidelity provides a critical tool in the field of palaeomagnetism. However, reliable interpretation of the recording fidelity of Fe3O4 particles is greatly diminished over time by progressive oxidation to less magnetic iron oxides, such as maghemite (γ-Fe2O3), with consequent alteration of remanent magnetization potentially having important geological significance. Here we use the complementary techniques of environmental transmission electron microscopy and off-axis electron holography to induce and visualize the effects of oxidation on the magnetization of individual nanoscale Fe3O4 particles as they transform towards γ-Fe2O3. Magnetic induction maps demonstrate a change in both strength and direction of remanent magnetization within Fe3O4 particles in the size range dominant in rocks, confirming that oxidation can modify the original stored magnetic information.
Variant adiponutrin confers genetic protection against cholestatic itch
Authors: Krawczyk Marcin , Milkiewicz Malgorzata , Marschall Hanns-Ulrich , Bartz Clemens , Grünhage Frank , Wunsch Ewa , Milkiewicz Piotr , Lammert Frank
Published: October 2014

Lysophosphatidic acid (LPA) mediates cholestatic pruritus. Recently the enzyme PNPLA3, expressed in liver and skin, was demonstrated to metabolise LPA. Here we assess the association of the PNPLA3 variant p.Ile148Met, known to be associated with (non-)alcoholic fatty liver disease (NAFLD) in genome-wide association studies, with cholestatic itch in 187 patients with primary biliary cirrhosis (PBC) and 250 PBC-free controls as well as 201 women with intrahepatic cholestasis of pregnancy (ICP) and 198 female controls without a history of ICP. Our hypothesis was that the intensity of cholestatic itch differs in carriers of distinct PNPLA3 p.Ile148Met genotypes. Patients with PBC carrying the allele p.148Met that confers an increased NAFLD risk reported less itching than carriers of the p.148Ile allele (ANOVA P = 0.048). The PNPLA3 p.148Ile allele increased the odds of requiring plasmapheresis for refractory pruritus (OR = 3.94, 95% CI = 0.91–17.00, P = 0.048). In line with these findings, the PNPLA3 p.148Met allele was underrepresented in the ICP cohort (OR = 0.66, 95% CI = 0.47–0.92, P = 0.013). Notwithstanding the need for further replication of these findings, we conclude that the PNPLA3 allele p.148Met might confer protection against cholestatic pruritus, possibly due to increased LPA-acyltransferase activity in liver and/or skin.
Carbon nanotube/gold nanoparticle composite-coated membrane as a facile plasmon-enhanced interface for sensitive SERS sensing
Authors: Zhang Kun , Ji Ji , Fang Xiaoni , Yan Ling , Liu Baohong
Published: October 2014

1D/0D-structured carbon nanotube/gold nanoparticle composites were synthesized and used to fabricate a simple and sensitive SERS sensor by filtering through a commercial membrane for on-site applications.
Oligopeptide–heavy metal interaction monitoring by hybrid gold nanoparticle based assay
Authors: Politi Jane , Spadavecchia Jolanda , Iodice Mario , de Stefano Luca
Published: October 2014

Phytochelatins are small peptides that can be found in several organisms, which use these oligopeptides to handle heavy metal elements.
Metal-free aminoamidiniumation employing N-iodosuccinimide: facile syntheses of bicyclic imidazolidiniums and cyclic vicinal diamines
Authors: Zhang Jun , Zhang Gengtao , Wu Weijie , Zhang Xuejun , Shi Min
Published: October 2014

NIS-mediated aminoamidiniumation has been developed for the syntheses of bicyclic imidazolidinium salts, which could be readily converted into 2-substituted pyrrolidine and indoline diamines.
Practical preparation of challenging amides from non-nucleophilic amines and esters under flow conditions
Authors: Vrijdag Johannes L. , Delgado Francisca , Alonso Nerea , De Borggraeve Wim M. , Pérez-Macias Natalia , Alcázar Jesus
Published: October 2014

Preparation of amides from low nucleophilic heterocyclic amines is achieved in 2 minutes under mild conditions.
A phenacrylate scaffold for tunable thiol activation and release
Authors: Sankar Rathinam K. , Kumbhare Rohan S. , Dharmaraja Allimuthu T. , Chakrapani Harinath
Published: October 2014

A scaffold for biological thiol mediated tunable activation and release of a cargo is reported.
A monomeric photosensitizer for targeted cancer therapy
Authors: Liang Ruizheng , Ma Lina , Zhang Lele , Li Chunyang , Liu Wendi , Wei Min , Yan Dan , Evans David G. , Duan Xue
Published: October 2014

A targeted photosensitizer used in photodynamic therapy (PDT) was fabricated by incorporation of zinc phthalocyanine (ZnPc) and folic acid (FA) into polyvinylpyrrolidone (PVP) micelles, which exhibits excellent anticancer performance revealed by both in vitro studies and in vivo tests.
Excess entropy scaling for the segmental and global dynamics of polyethylene melts
Authors: Voyiatzis Evangelos , Müller-Plathe Florian , Böhm Michael C.
Published: October 2014

The range of validity of the Rosenfeld and Dzugutov excess entropy scaling laws is analyzed for unentangled linear polyethylene chains.
Catalytic enantioselective synthesis of α-nitroepoxides via aminolytic kinetic resolution
Authors: Meninno Sara , Napolitano Loris , Lattanzi Alessandra
Published: October 2014

The first enantioselective synthesis of β-aryl-substituted α-nitroepoxides, exploiting an organocatalyzed aminolytic kinetic resolution (AKR), has been developed.
Mitochondrial energy metabolism in the hepatopancreas of freshwater crabs (Sinopotamon henanense) after cadmium exposure
Authors: Yang Jian , Liu Dongmei , He Yongji , Wang Lan
Published: October 2014

Following Cd exposure, volume expansion and swollen matrices in more mitochondria could lead to disturbance in mitochondrial morphology.
Out-of-equilibrium dynamics of photoexcited spin-state concentration waves
Authors: Marino A. , Buron-Le Cointe M. , Lorenc M. , Toupet L. , Henning R. , DiChiara A. D. , Moffat K. , Bréfuel N. , Collet E.
Published: October 2014

The spin crossover compound [FeIIH2L2-Me][PF6]2 presents a two-step phase transition. In the intermediate phase, a spin state concentration wave (SSCW) appears resulting from a symmetry breaking (cell doubling) associated with a long-range order of alternating high and low spin molecular states. By combining time-resolved optical and X-ray diffraction measurements on a single crystal, we study how such a system responds to femtosecond laser excitation and we follow in real time the erasing and rewriting of the SSCW.
Upgrading of glycerol acetals by thermal catalyst-free transesterification of dialkyl carbonates under continuous-flow conditions
Authors: Selva M. , Guidi S. , Noè M.
Published: October 2014

At 225–300 °C and 20–70 bar, glycerol acetals are upgraded by a continuous-flow catalyst-free transesterification of dialkyl and alkylene carbonates.
Catalytic conversion of carbohydrate-derived oxygenates over HZSM-5 in a tandem micro-reactor system
Authors: Wang Kaige , Zhang Jing , H. Shanks Brent , Brown Robert C.
Published: October 2014

Effect of functionality, molecular size, and interactions of oxygenates over HZSM-5 were investigated to understand the reaction mechanism of catalytic fast pyrolysis of carbohydrates.
Estimation of the formation rates of polyatomic species of heavy metals in plutonium analyses using a multicollector ICP-MS with a desolvating nebulizer
Authors: Mitroshkov A. V. , Olsen K. B. , Thomas M. L.
Published: October 2014

Analyses of International Atomic Energy Agency (IAEA) and environmental samples for the Pu isotopic content are conducted normally at very low concentrations of Pu—usually in the range of parts per trillion and even more often at the parts per quadrillion level.
Molecular dynamics-based discovery of novel phosphodiesterase-9A inhibitors with non-pyrazolopyrimidinone scaffolds
Authors: Li Zhe , Lu Xiao , Feng Ling-Jun , Gu Ying , Li Xingshu , Wu Yinuo , Luo Hai-Bin
Published: October 2014

Viamolecular dynamics-based virtual screening, 15 novel phosphodiesterase-9A inhibitors with five non-pyrazolopyrimidinone scaffolds were discovered.
In vitro selection of DNA-based aptamers that exhibit RNA-like conformations using a chimeric oligonucleotide library that contains two different xeno-nucleic acids
Authors: Hagiwara Kenta , Fujita Hiroto , Kasahara Yuuya , Irisawa Yuuta , Obika Satoshi , Kuwahara Masayasu
Published: October 2014

Rapid selection of 2′,4′-BNA/FNA chimeric aptamers paves the way for further development of XNA aptamers having unconventional sugars.
Magnetic and electric field assisted electrospun polyamide nanofibers for on-line μ-solid phase extraction and HPLC
Authors: Bagheri Habib , Piri-Moghadam Hamed , Rastegar Soroush
Published: October 2014

The effects of applied magnetic and electric fields on electrospinning were investigated to produce more efficient nanofibers.
In situ anodic growth of rod-like TiO2 coating on a Ti wire as a selective solid-phase microextraction fiber
Authors: Li Yi , Ma Mingguang , Zhang Min , Yang Yaoxia , Wang Xuemei , Du Xinzhen
Published: October 2014

A novel rod-like TiO2 based SPME coating was directly fabricated by in situ anodization of Ti wire (Fig. 1). It has larger surface area and longer service time for sensitive determination of ultraviolet filters in environmental water samples.
Influence of anionic co-ligands on the structural diversity and catecholase activity of copper(ii) complexes with 2-methoxy-6-(8-iminoquinolinylmethyl)phenol
Authors: Shyamal Milan , Mandal Tarun Kanti , Panja Anangamohan , Saha Amrita
Published: October 2014

Pseudohalides induced structural diversity and catecholase activity of copper(ii) complexes are reported. The NCO-bound compound is the first example of a mononuclear square planar complex exhibiting catecholase activity.
Efficient dehydration of the organic solvents through graphene oxide (GO)/ceramic composite membranes
Authors: Li Guihua , Shi Lei , Zeng Gaofeng , Zhang Yanfeng , Sun Yuhan
Published: October 2014

Al2O3 tube supported GO composite membranes with submicron thickness and improved mechanical strength were fabricated via a filter-pressing deposition method. High separation performance was achieved in the pervaporation of solvent–water mixtures.
Towards an understanding of the role of hyper-branched oligomers coated on cathodes, in the safety mechanism of lithium-ion batteries
Authors: Liu Hsueh-Ming , Saikia Diganta , Wu Hung-Chun , Su Ching-Yi , Wang Tsung-Hsiung , Li Yu-Han , Pan Jing-Pin , Kao Hsien-Ming
Published: October 2014

The self-terminated oligomers with hyper-branched architecture (STOBA) coated on Li(Ni0.4Co0.2Mn0.4)O2cathode material suppress thermal runaway and prevent explosion of lithium-ion batteries.
Effects of Ag-ion implantation on the performance of DSSCs with a tri-layer TiO2 film
Authors: Luo Jun , Zhou Jiawei , Guo Haibo , Yang Weiguang , Liao Bin , Shi Weimin , Chen Yigang
Published: October 2014

Ag-ions take different roles in titania films as a function of the dose of implanted Ag ions.
Mesoporous graphitic carbon nitride as a heterogeneous catalyst for photoinduced copper(i)-catalyzed azide–alkyne cycloaddition
Authors: Dadashi-Silab Sajjad , Kiskan Baris , Antonietti Markus , Yagci Yusuf
Published: October 2014

A new protocol has been developed for the photoinduced CuAAC click reaction using heterogeneous mesoporous graphitic carbon nitride as the photocatalyst.
Ormosil nanoparticles as a sustained-release drug delivery vehicle
Authors: Roy Indrajit , Kumar Pramod , Kumar Rajiv , Ohulchanskyy Tymish Y. , Yong Ken-Tye , Prasad Paras N.
Published: October 2014

Tem images (above) and release profiles (below) of encapsulated drug from ormosil nanoparticles with small (orm-s), medium (orm-m) and large (orm-l) sizes.
Synthesis, characterization, and field-effect transistor performance of a two-dimensional starphene containing sulfur
Authors: Zou Sufen , Wang Yingfeng , Gao Jianhua , Liu Xiaoxia , Hao Wanglong , Zhang Huarong , Zhang Haixia , Xie Hui , Yang Chengdong , Li Hongxiang , Hu Wenping
Published: October 2014

A novel starphene containing sulfur exhibits an excellent FET performance with a mobility of 0.56 cm2 V−1 s−1 based on the single-crystal nanowires.
A two-faced “Janus-like” unimolecular rectifier exhibits rectification reversal
Authors: Johnson M. S. , Kota R. , Mattern D. L. , Hill C. M. , Vasiliu M. , Dixon D. A. , Metzger R. M.
Published: October 2014

A new monolayer rectifier with pyrene donor (D) and perylenebisimide acceptor (A) rectifies A → D below 2.0 Volts, but A ← D beyond that.
Trace analysis of methylated and hydroxymethylated cytosines in DNA by isotope-dilution LC–MS/MS: first evidence of DNA methylation in Caenorhabditis elegans
Authors: Hu Chiung-Wen , Chen Jian-Lian , Hsu Yu-Wen , Yen Cheng-Chieh , Chao Mu-Rong
Published: October 2014

From 1986 to the present, the popular research model organism Caenorhabditis elegans has been thought to completely lack DNA methylation and seems to have lost DNA methylation enzymes from its genomes. In the present study, we report the development of a sensitive and selective assay based on LC–MS/MS to simultaneously measure 5-methyl-2′-deoxycytidine (5-mdC) and 5-hydroxymethyl-2′-deoxycytidine (5-hmdC) in DNA hydrolysates. With the use of isotope internal standards ([2H3]5-mdC and [2H3]5-hmdC) and online solid-phase extraction, the detection limits of 5-mdC and 5-hmdC were estimated to be 0.01 and 0.02 pg respectively, which correspond to a 0.000006% and 0.00001% methylation and hydroxymethylation level. This method was applied to investigate whether DNA methylation/hydroxymethylation exists in C. elegans. The present study for the first time demonstrates that 5-mdC is present in C. elegans genomic DNA (0.0019–0.0033% of cytosine methylated) using LC–MS/MS, whereas another epigenetic modification, 5-hmdC, is not detectable. Furthermore, we found that C. elegans DNA was hypo- or hyper-methylated in a dose-dependent manner by the DNA methyltransferase (DNMT)-inhibiting drug decitabine (5-aza-2′-deoxycytidine) or cadmium respectively. Our data support the possible existence of an active DNA-methylation mechanism in C. elegans, in which unidentified DNMTs could be involved. The present study highlights the importance of re-evaluating the evolutionary conservation of DNA-methylation machinery in nematodes which were traditionally considered to lack functional DNA methylation.
TheEscherichia colimajor exoribonuclease RNase II is a component of the RNA degradosome
Authors: Lu Feng , Taghbalout Aziz
Published: October 2014

Multiprotein complexes that carry out RNA degradation and processing functions are found in cells from all domains of life. In Escherichia coli, the RNA degradosome, a four-protein complex, is required for normal RNA degradation and processing. In addition to the degradosome complex, the cell contains other ribonucleases that also play important roles in RNA processing and/or degradation. Whether the other ribonucleases are associated with the degradosome or function independently is not known. In the present work, IP (immunoprecipitation) studies from cell extracts showed that the major hydrolytic exoribonuclease RNase II is associated with the known degradosome components RNaseE (endoribonuclease E), RhlB (RNA helicase B), PNPase (polynucleotide phosphorylase) and Eno (enolase). Further evidence for the RNase II-degradosome association came from the binding of RNase II to purified RNaseE in far western affinity blot experiments. Formation of the RNase II–degradosome complex required the degradosomal proteins RhlB and PNPase as well as a C-terminal domain of RNaseE that contains binding sites for the other degradosomal proteins. This shows that the RNase II is a component of the RNA degradosome complex, a previously unrecognized association that is likely to play a role in coupling and coordinating the multiple elements of the RNA degradation pathways.
Adaptive AFM scan speed control for high aspect ratio fast structure tracking
Authors: Ahmad Ahmad , Schuh Andreas , Rangelow Ivo W.
Published: October 2014

Improved imaging rates in Atomic Force Microscopes (AFM) are of high interest for disciplines such as life sciences and failure analysis of semiconductor wafers, where the sample topology shows high aspect ratios. Also, fast imaging is necessary to cover a large surface under investigation in reasonable times. Since AFMs are composed of mechanical components, they are associated with comparably low resonance frequencies that undermine the effort to increase the acquisition rates. In particular, high and steep structures are difficult to follow, which causes the cantilever to temporarily loose contact to or crash into the sample. Here, we report on a novel approach that does not affect the scanner dynamics, but adapts the lateral scanning speed of the scanner. The controller monitors the control error signal and, only when necessary, decreases the scan speed to allow the z-piezo more time to react to changes in the sample's topography. In this case, the overall imaging rate can be significantly increased, because a general scan speed trade-off decision is not needed and smooth areas are scanned fast. In contrast to methods trying to increase the z-piezo bandwidth, our method is a comparably simple approach that can be easily adapted to standard systems.
Boron Doped diamond films as electron donors in photovoltaics: An X-ray absorption and hard X-ray photoemission study
Authors: Kapilashrami M. , Conti G. , Zegkinoglou I. , Nemšák S. , Conlon C. S. , Törndahl T. , Fjällström V. , Lischner J. , Louie Steven G. , Hamers R. J. , Zhang L. , Guo J.-H. , Fadley C. S. , Himpsel F. J.
Published: October 2014

Highly boron-doped diamond films are investigated for their potential as transparent electron donors in solar cells. Specifically, the valence band offset between a diamond film (as electron donor) and Cu(In,Ga)Se2 (CIGS) as light absorber is determined by a combination of soft X-ray absorption spectroscopy and hard X-ray photoelectron spectroscopy, which is more depth-penetrating than standard soft X-ray photoelectron spectroscopy. In addition, a theoretical analysis of the valence band is performed, based on GW quasiparticle band calculations. The valence band offset is found to be small: VBO = VBMCIGS – VBMdiamond = 0.3 eV ± 0.1 eV at the CIGS/Diamond interface and 0.0 eV ± 0.1 eV from CIGS to bulk diamond. These results provide a promising starting point for optimizing the band offset by choosing absorber materials with a slightly lower valence band maximum.
Preparation of magnetized nanodusty plasmas in a radio frequency-driven parallel-plate reactor
Authors: Tadsen Benjamin , Greiner Franko , Piel Alexander
Published: October 2014

Nanodust is produced in an rf-driven push-pull parallel-plate reactor using argon with an acetylene admixture at 5–30 Pa. A scheme for the preparation of nanodust clouds with particle radii up to 400 nm for investigations in magnetized plasmas is proposed. The confinement that keeps the nanodust of different radii inside a moderately magnetized discharge (B ≤ 500 mT) is investigated by a comparison of 2d-Langmuir probe measurements in the dust-free plasma without and with a magnetic field and by the analysis of scattered light of nanodust clouds. It is shown that the dust cloud changes its shape when the dust density changes. This results in a reversed α-γ′ transition from a dense dust cloud with a central disk-like void to a dilute dust cloud with a toroidal void. When the dust density is further reduced, filaments are observed in the central part of the cloud, which were absent in the high-density phase. It is concluded that the dense nanodust cloud is able to suppress plasma filamentation in magnetized plasmas.
Cooee bitumen. II. Stability of linear asphaltene nanoaggregates
Authors: Lemarchand Claire A. , Schrøder Thomas B. , Dyre Jeppe C. , Hansen Jesper S.
Published: October 2014

Asphaltene and smaller aromatic molecules tend to form linear nanoaggregates in bitumen. Over the years bitumen undergoes chemical aging and during this process, the size of the nanoaggregate increases. This increase is associated with an increase in viscosity and brittleness of the bitumen, eventually leading to road deterioration. This paper focuses on understanding the mechanisms behind nanoaggregate size and stability. We used molecular dynamics simulations to quantify the probability of having a nanoaggregate of a given size in the stationary regime. To model this complicated behavior, we chose first to consider the simple case where only asphaltene molecules are counted in a nanoaggregate. We used a master equation approach and a related statistical mechanics model. The linear asphaltene nanoaggregates behave as a rigid linear chain. The most complicated case where all aromatic molecules are counted in a nanoaggregate is then discussed. The linear aggregates where all aromatic molecules are counted seem to behave as a flexible linear chain.
Investigating the effective range of vacuum ultraviolet-mediated breakdown in high-power microwave metamaterials
Authors: Liu Chien-Hao , Neher Joel D. , Booske John H. , Behdad Nader
Published: October 2014

Metamaterials and periodic structures operating under high-power excitations are susceptible to breakdown. It was recently demonstrated that a localized breakdown created in a given region of a periodic structure can facilitate breakdown in other regions of the structure where the intensity of the incident electromagnetic fields may not be high enough to cause breakdown under normal circumstances. It was also demonstrated that this phenomenon is due to the generation of vacuum ultraviolet radiation at the location of the initial discharge, which propagates to the neighboring regions (e.g., other unit cells in a periodic structure) and facilitates the generation of a discharge at a lower incident power level. In this paper, we present the results of an experimental study conducted to determine the effective range of this physical phenomenon for periodic structures that operate in air and in pure nitrogen gas at atmospheric pressure levels. It is demonstrated that when breakdown is induced in a periodic structure using a high-power pulse with a frequency of 9.382 GHz, duration of 0.8 μs, and peak power level of 25 kW, this phenomenon is highly likely to happen in radii of approximately 16–17 mm from the location of the initial discharge under these test conditions. The results of this study are significant in designing metamaterials and periodic structures for high-power microwave applications as they suggest that a localized discharge created in such a periodic structure with a periodicity less than 16–17 mm can spread over a large surface and result in a distributed discharge.
Grazing incidence angle based sensing approach integrated with fiber-optic Fourier transform infrared (FO-FTIR) spectroscopy for remote and label-free detection of medical device contaminations
Authors: Hassan Moinuddin , Ilev Ilko
Published: October 2014

Contamination of medical devices has become a critical and prevalent public health safety concern since medical devices are being increasingly used in clinical practices for diagnostics, therapeutics and medical implants. The development of effective sensing methods for real-time detection of pathogenic contamination is needed to prevent and reduce the spread of infections to patients and the healthcare community. In this study, a hollow-core fiber-optic Fourier transform infrared spectroscopy methodology employing a grazing incidence angle based sensing approach (FO-FTIR-GIA) was developed for detection of various biochemical contaminants on medical device surfaces. We demonstrated the sensitivity of FO-FTIR-GIA sensing approach for non-contact and label-free detection of contaminants such as lipopolysaccharide from various surface materials relevant to medical device. The proposed sensing system can detect at a minimum loading concentration of approximately 0.7 μg/cm2. The FO-FTIR-GIA has the potential for the detection of unwanted pathogen in real time.
Electron emission in a source-collector sheath system: A kinetic study
Authors: Rizopoulou N. , Robinson A. P. L. , Coppins M. , Bacharis M.
Published: October 2014

The classical source-collector sheath system describes a plasma that forms between a Maxwellian source and an absorbing wall. The plasma is assumed to be collisionless and without ionization. Two distinct areas are being formed: the collector sheath, an ion-rich region in contact with the absorbing boundary, and the source sheath, which is an electron-rich area near the Maxwellian source. In this work, we study a modified version of the classical source-collector sheath system, where the wall is no longer absorbing but emits electrons. As a result, we have two different types of collector sheath, one where a potential well is formed and one without a potential well. We examine the effect of electron emission for a range of conditions for the plasma and the emitted electrons. In the first part of this work, we study the problem analytically, and in the second, using our kinetic Vlasov code, Yggdrasil. The simulation results are in very good agreement with the predictions of our theoretical model.
Marginal instability threshold condition of the aperiodic ordinary mode in equal-mass plasmas
Authors: Vafin S. , Schlickeiser R. , Yoon P. H.
Published: October 2014

The purely growing ordinary (O) mode instability for counter-streaming bi-Maxwellian plasma particle distribution functions has recently received renewed attention due to its importance for the solar wind plasma. Here, the analytical marginal instability condition is derived for magnetized plasmas consisting of equal-mass charged particles, distributed in counter-streams with equal temperatures. The equal-mass composition assumption enormously facilitates the theoretical analysis due to the equality of the values of the electron and positron (positive and negative ion) plasma and gyrofrequencies. The existence of a new instability domain of the O-mode at small plasma beta values is confirmed, when the parallel counter-stream free energy exceeds the perpendicular bi-Maxwellian free energy.
Optical properties of magnesium doped AlxGa1−xN (0.61 ≤ x ≤ 0.73)
Authors: Feneberg Martin , Osterburg Sarah , Romero María Fátima , Garke Bernd , Goldhahn Rüdiger , Neumann Maciej D. , Esser Norbert , Yan Jianchang , Zeng Jianping , Wang Junxi , Li Jinmin
Published: October 2014

We investigate the optical properties of AlxGa1–xN:Mg with aluminum content of 0.61 ≤ x ≤ 0.733 in comparison to undoped and silicon doped reference samples. The ordinary dielectric functions, excitation, and emission spectra are reported at different temperatures. A comprehensive analysis yields quantitative data on the valence band structure of the ternary alloy, i.e., splitting and order of valence bands with different symmetries. Finally, the near band gap emission in AlGaN:Mg is found to be most probably dominated by donor to free-hole recombination.
Acoustic radiation force on a double-layer microsphere by a Gaussian focused beam
Authors: Wu Rongrong , Cheng Kaixuan , Liu Xiaozhou , Liu Jiehui , Mao Yiwei , Gong Xiufen
Published: October 2014

A new model for calculating the radiation force on double-layer microsphere is proposed based on the ray acoustics approach. The axial acoustic radiation force resulting from a focused Gaussian beam incident on spherical shells immersed in water is examined theoretically in relation to its thickness and the contents of its double-layer. The attenuation both in the water and inside the sphere is considered in this method, which cannot be ignored while the high frequency ultrasonic is used. Results of numerical calculations are presented for fat and low density polyethylene materials, with the hollow region filled with animal oil, water, or air. These results show how the acoustic impedance and the sound velocity of both layers, together with the thickness of the shell, affect the acoustic radiation force.
Theoretical and experimental studies of distance dependent response of micro-ring resonator-based ultrasonic detectors for photoacoustic microscopy
Authors: Zhang Zhen , Dong Biqin , Li Hao , Zhou Fan , Zhang Hao F. , Sun Cheng
Published: October 2014

We present in this paper a systematic study of the distance dependent detection characteristics of the newly developed micro-ring resonator (MRR)-based ultrasonic detector for photoacoustic microscopy (PAM). A simple analytic model was first developed to study the steady-state response to the continuous ultrasonic waves. While placing the MRR detector at the acoustic far-field provides longer working distance and broader field of view, the detection at acoustic near-field offers the improved sensitivity and broader bandwidth but at the cost of reduction in the field of view. Furthermore, a numerical model was developed to analyze the transient response to the photoacoustic-induced impulsive waves. Notably, far-field detection exhibits a flat wavefront of its response pattern in the time domain while large distortions are clearly visible in the case of near-field detection. Finally, both analytic and numerical models are validated by experimental studies. This work establishes a theoretical framework for quantitatively analyzing the trade-offs between near-field and far-field detection using MRR detector, creating a guideline for optimizing the PAM for various applications in biomedical imaging and diagnostics.
Electrically tunable hot-silicon terahertz attenuator
Authors: Wang Minjie , Vajtai Robert , Ajayan Pulickel M. , Kono Junichiro
Published: October 2014

We have developed a continuously tunable, broadband terahertz attenuator with a transmission tuning range greater than 103. Attenuation tuning is achieved electrically, by simply changing the DC voltage applied to a heating wire attached to a bulk silicon wafer, which controls its temperature between room temperature and ∼550 K, with the corresponding free-carrier density adjusted between ∼1011 cm−3 and ∼1017 cm−3. This “hot-silicon”-based terahertz attenuator works most effectively at 450–550 K (corresponding to a DC voltage variation of only ∼7 V) and completely shields terahertz radiation above 550 K in a frequency range of 0.1–2.5 THz. Both intrinsic and doped silicon wafers were tested and demonstrated to work well as a continuously tunable attenuator. All behaviors can be understood quantitatively via the free-carrier Drude model taking into account thermally activated intrinsic carriers.
Optical, ferroelectric, and piezoresponse force microscopy studies of pulsed laser deposited Aurivillius Bi5FeTi3O15 thin films
Authors: Kooriyattil Sudheendran , Pavunny Shojan P. , Barrionuevo Danilo , Katiyar Ram S.
Published: October 2014

Bi5FeTi3O15 (BFTO) based Aurivillius ferroelectric thin films were fabricated on strontium ruthanate coated amorphous fused silica substrates using pulsed laser deposition technique. Optical, ferroelectric, and piezoresponse properties of these thin films were investigated. The estimated refractive index (n) and extinction coefficient (k) for these films were in the range from 2.40 to 2.59 and 0.012 to 0.19, respectively. The bandgap of the BFTO thin layers was estimated to be 2.88 eV. Domain switching and hysteresis loops of BFTO films were studied utilizing piezoresponse force microscopy (PFM). The measured apparent polarization (Pr) and coercive field (Ec) for the samples were 20 μC/cm2 and 250 kV/cm, respectively. The amplitude and phase hysteresis curves obtained from PFM characterization reveal that these films can be switched below 5 V. These results suggest that BFTO in thin film form is a promising material for photo ferroelectric and optoelectronic devices applications.
Integrated two-cylinder liquid piston Stirling engine
Authors: Yang Ning , Rickard Robert , Pluckter Kevin , Sulchek Todd
Published: October 2014

Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.