bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors associated with the composition and diversity of the cervical microbiota of reproductive-age Black South African women: a retrospective cross-sectional study
Authors: Onywera Harris , Williamson Anna-Lise , Mbulawa Zizipho Z.A. , Coetzee David , Meiring Tracy L. 
Published: August 2019

BackgroundLactobacillusspp. are common bacteria in the cervical and vaginal microbiota (CVM) and are thought to represent a “healthy” cervicovaginal state. Several studies have found an independent association between ethnicity/race and cervical and vaginal microbiota (CVM) composition. Women of sub-Saharan African descent appear to be significantly more likely to have non-Lactobacillus-dominated CVM compared to women of European descent. The factors contributing to these differences remain to be fully elucidated. The CVM of Black South African women and factors influencing their CVM remain understudied. In this study, we characterized the cervical microbiota of reproductive-age South African women and assessed the associations of these microbiota with participants’ metadata.MethodsThe cervical microbiota from cervical DNA of 62 reproductive-age women were profiled by Ion Torrent sequencing the V4 hypervariable region of the bacterial 16S ribosomal RNA (rRNA) gene and analyzed with the Quantitative Insights Into Microbial Ecology (QIIME), UPARSE, and metagenomeSeq tools. Associations between cervical microbiota and participants’ metadata were assessed using GraphPad Prism, R packages and an in-house script.ResultsThe cervical microbiota clustered into three distinct community state types (CSTs):Lactobacillus iners-dominated cervical microbiota (CST I (38.7%, 24/62)), unclassifiedLactobacillus-dominated cervical microbiota (CST II (4.8%, 3/62)), and diverse cervical microbiota (CST III (56.5%, 35/62)) with an array of heterogeneous bacteria, predominantly the bacterial vaginosis (BV)-associatedGardnerella,Prevotella,Sneathia, andShuttleworthia. CST III was associated with BV (p = 0.001). Women in CST I were more likely to be on hormonal contraception, especially progestin-based, compared to women in CST III (odds ratio: 5.2 (95% CI [1.6–17.2]);p = 0.005). Women on hormonal contraception had a significantly lower alpha (Shannon indices: 0.9 (0.2–1.9) versus 2.3 (0.6–2.3);p = 0.025) and beta (permutational multivariate analysis of variance (PERMANOVA) pseudo-F statistic =4.31,p = 0.019) diversity compared to non-users. There was no significant difference in the alpha (Shannon indices: 1.0 (0.3–2.2) versus 1.9 (0.3–2.2);p = 0.483) and beta (PERMANOVA pseudo-Fstatistic = 0.89,p = 0.373) diversity in women with versus without human papillomavirus infection.ConclusionsThe majority of Black women in our study had non-Lactobacillus-dominated cervical microbiota. Additional studies are needed to examine whether such microbiota represent abnormal, intermediate or variant states of health. Lastly, the association of hormonal contraception withL. inersdominance requires further in-depth research to confirm this association, determine its biological mechanism and whether it has a beneficial effect on the cervicovaginal health.
Atom‐by‐Atom Fabrication of Single and Few Dopant Quantum Devices
Authors: Wyrick Jonathan , Wang Xiqiao , Kashid Ranjit V. , Namboodiri Pradeep , Schmucker Scott W. , Hagmann Joseph A. , Liu Keyi , Stewart Michael D. , Richter Curt A. , Bryant Garnett W. , Silver Richard M. 
Published: August 2019

AbstractAtomically precise fabrication has an important role to play in developing atom‐based electronic devices for use in quantum information processing, quantum materials research, and quantum sensing. Atom‐by‐atom fabrication has the potential to enable precise control over tunnel coupling, exchange coupling, on‐site charging energies, and other key properties of basic devices needed for solid‐state quantum computing and analog quantum simulation. Using hydrogen‐based scanning probe lithography, individual dopant atoms are deterministically placed relative to atomically aligned contacts and gates to build single electron transistors, single atom transistors, and gate‐controlled quantum sensing devices. The key steps required to fabricate and demonstrate the essential building blocks needed for spin selective initialization/readout and coherent quantum manipulation are described.
Irradiation of Transition Metal Dichalcogenides Using a Focused Ion Beam: Controlled Single‐Atom Defect Creation
Authors: Thiruraman Jothi Priyanka , Masih Das Paul , Drndić Marija 
Published: August 2019

AbstractManipulation and structural modifications of 2D materials for nanoelectronic and nanofluidic applications remain obstacles to their industrial‐scale implementation. Here, it is demonstrated that a 30 kV focused ion beam can be utilized to engineer defects and tailor the atomic, optoelectronic, and structural properties of monolayer transition metal dichalcogenides (TMDs). Aberration‐corrected scanning transmission electron microscopy is used to reveal the presence of defects with sizes from the single atom to 50 nm in molybdenum (MoS2) and tungsten disulfide (WS2) caused by irradiation doses from 1013 to 1016 ions cm−2. Irradiated regions across millimeter‐length scales of multiple devices are sampled and analyzed at the atomic scale in order to obtain a quantitative picture of defect sizes and densities. Precise dose value calculations are also presented, which accurately capture the spatial distribution of defects in irradiated 2D materials. Changes in phononic and optoelectronic material properties are probed via Raman and photoluminescence spectroscopy. The dependence of defect properties on sample parameters such as underlying substrate and TMD material is also investigated. The results shown here lend the way to the fabrication and processing of TMD nanodevices.
Brewster Mode‐Enhanced Sensing with Hyperbolic Metamaterial
Authors: Sreekanth Kandammathe Valiyaveedu , Mahalakshmi Perumal , Han Song , Mani Rajan Murugan Senthil , Choudhury Pankaj Kumar , Singh Ranjan 
Published: August 2019

AbstractHyperbolic metamaterials (HMMs) are used to demonstrate extreme sensitivity biosensing by exciting their high‐k modes. However, momentum couplers, such as subwavelength diffraction grating or bulky high‐index prism, are required to excite these nonradiative modes, which is not cost‐effective and thus not suitable for point‐of‐care applications. Here, a cost‐effective and scalable HMM‐based sensor platform is proposed and experimentally demonstrated, by exciting the Brewster mode of HMM from free‐space. The excitation of Brewster modes is shown in a multilayered HMM comprising of alternating thin layers of TiN and phase change material, such as Sb2S3. Brewster modes in the hyperbolic region occur due to abrupt phase change, and enhanced Goos–Hänchen shift is realized at the Brewster angle. The enhanced refractive index sensing is demonstrated by exploiting the singular phase of light associated with the Brewster mode of the proposed HMM. This microfluidics integrated lithography‐free nanophotonic device can be a potential sensor platform for a cost‐effective development of label‐free biosensors for point‐of‐care applications.
Quantifying Performance of Permeation Barrier—Encapsulation Systems for Flexible and Glass‐Based Electronics and Their Application to Perovskite Solar Cells
Authors: Castro‐Hermosa Sergio , Top Michiel , Dagar Janardan , Fahlteich John , Brown Thomas M. 
Published: August 2019

AbstractEffective transparent barrier/encapsulation systems represent a key enabling technology for large‐area electronics. Securing stability to the environment is vital. Here, the effects of architectures, application processes, and water vapor transmission rates (WVTR) of transparent flexible ultra‐high permeation barrier films (UHPBF) applied to substrates with adhesive resins are unraveled for attaining long lifetime, and compared with polyethylene terephthalate and glass barriers. How strongly performance of barrier/adhesive systems depends on barrier orientation, adhesion, manipulation, defects, and storage procedures is quantified via calcium tests. Furthermore, it is found that introducing an additional adhesion‐promoting layer on the standard UHPBF stack reduces WVTRs by a factor of 5 compared to barriers without it. Finally, barriers are used for sealing and encapsulation of perovskite solar cells (PSCs) enabling the extraction of a relationship between WVTRs of barrier/adhesive systems and degradation rates (DR) of PSCs. DR fall exponentially when WVTRs decrease from 101 to 10−3 g m−2 d−1. Outside that range any gains or losses are mitigated by tailing of the sigmoid curve relating the two parameters. Results highlight important factors which will help those developing strategies relating to encapsulation, barrier, adhesive and sealant systems and stable optoelectronic devices on glass and flexible substrates.
Transparent Magnetoelectric Materials for Advanced Invisible Electronic Applications
Authors: Polícia Rita , Lima Ana Catarina , Pereira Nélson , Calle Esther , Vázquez Manuel , Lanceros‐Mendez Senentxu , Martins Pedro 
Published: August 2019

AbstractThe need for flexible and transparent smart materials is leading to substantial advances in principles, material combinations, and technologies. Particularly, the development of optically transparent magnetoelectric (ME) materials will open the range of applications to new directions such as transparent sensors, touch display panels, multifunctional flat panel displays, and optical magnetic coatings. In this work, a flexible and transparent ME composite is made of magnetostrictive Fe72.5Si12.5B15 microwires and piezoelectric poly(vinylidene fluoride‐trifluoroethylene). The high magnetostriction of Fe72.5Si12.5B15 (35 ppm) enables superior ME voltage response (65 mV cm−1 Oe−1) obtained at the critical longitudinal magnetic field equating the transverse anisotropy (14500 A m−1) on the external shell of the microwire.
A New View of Supercapacitors: Integrated Supercapacitors
Authors: Zhu Qiancheng , Zhao Danyang , Cheng Mingyu , Zhou Jianqing , Owusu Kwadwo Asare , Mai Liqiang , Yu Ying 
Published: August 2019

AbstractCharging times ranging from seconds to minutes with high power densities can be achieved by electrochemical capacitors in principle. Over the past few decades, the performance of supercapacitors has been greatly improved by the utilization of new materials, preparation of unique nanostructures, investigation of electrolytes, and so on. However, the discovery of the related basic theory is very limited. Herein, a new view of a supercapacitor called the “integrated supercapacitor” is proposed. The electrode of the integrated supercapacitor consists of certain positive and negative materials. With this design, a single integrated electrode can work in both the positive and negative potential windows simultaneously. Additionally, the integrated full supercapacitor device shows a much higher capacitance and wider potential window than traditional single symmetric and asymmetric supercapacitors, which results from its multiple mechanisms, including the traditional positive//positive symmetric, positive//negative asymmetric, and negative//negative symmetric full supercapacitor mechanisms.
In Operando Visualization of the Electrochemical Formation of Liquid Polybromide Microdroplets
Authors: Wu Yutong , Huang Po‐Wei , Howe Joshua D. , Yan Yu , Martinez Jose , Marianchuk Anna , Zhang Yamin , Chen Hang , Liu Nian 
Published: August 2019

AbstractZinc–bromine flow batteries are promising for stationary energy storage, and bromine‐complexing agents have been used to form phase‐separated liquid polybromide products. However, an understanding of the dynamics of polybromide nucleation is limited due to the beam sensitivity and complexity of polybromides. Here we report an in operando platform composed of dark‐field light microscopy and a transparent electrochemical cell to reveal the dynamics of polybromide formation in their native environment. Using our platform, we confirm and reveal the liquid nature, chemical composition, pinning effect (strong interaction with Pt), residual effect (residual charge products on the surface), self‐discharging, and over‐oxidation of the polybromide products. The results provide insights into the role of complexing agents and guide the future design of zinc–bromine flow batteries. Furthermore, our in operando platform can potentially be used to study sensitive species and phases in other electrochemical reactions.
Konformativer Umbau von Porphyrinen als Rezeptoren mit schaltbaren N‐H⋅⋅⋅X‐Bindungsmodi
Authors: Norvaiša Karolis , Flanagan Keith J. , Gibbons Dáire , Senge Mathias O. 
Published: August 2019

AbstractDie Selektivität und funktionale Variabilität von Porphyrinkofaktoren basiert typischerweise auf der Substratbindung durch Metalloporphyrine, wobei die Pyrrolstickstoffatome nur zur Chelatisierung der Metallionen dienen. In einem ersten Schritt zu Porphyrinzentren mit “enzymähnlicher” Aktivität zeigt eine strukturelle und spektroskopische Untersuchung der Substratbindung im Kern jedoch, dass ein sattelverbogenes Porphyrin mit peripheren Aminorezeptorgruppen (1, 2,3,7,8,12,13,17,18‐Oktaethyl‐5,10,15,20‐tetrakis(2‐aminophenyl)porphyrin), abhängig von der Azidität der Lösung, Analyte in einer schaltbaren Weise koordiniert. Das supramolekulare Ensemble weist eine hohe Affinität und Selektivität für das Pyrophosphatanion (2.26±0.021)×109 m−1 auf. 1H‐NMR‐Spektroskopie liefert Einblicke in den wahrscheinlichen Bindungsmodus und erlaubt die Charakterisierung der Atropisomere, deren Struktur auch durch Röntgenstrukturanalysen aufgeklärt wurde.
DNA Origami Nanoplate‐Based Emulsion with Nanopore Function
Authors: Ishikawa Daisuke , Suzuki Yuki , Kurokawa Chikako , Ohara Masayuki , Tsuchiya Misato , Morita Masamune , Yanagisawa Miho , Endo Masayuki , Kawano Ryuji , Takinoue Masahiro 
Published: August 2019

AbstractBio‐inspired functional microcapsules have attracted increasing attention in many fields from physical/chemical science to artificial‐cell engineering. Although particle‐stabilised microcapsules are advantageous for their stability and functionalisation potential, versatile methods for their functionalisation are desired to expand their possibilities. This study reports a water‐in‐oil microdroplet stabilised with amphiphilic DNA origami nanoplates. By utilising DNA nanotechnology, DNA nanoplates were designed as a nanopore device for ion transportation and to stabilise the oil–water interface. Microscopic examination revealed the microcapsule formed by the accumulation of amphiphilic DNA nanoplates at the oil–water interface. Ion current measurements revealed the nanoplate pores functioned as channel to transport ions. These findings provide a general strategy for the programmable design of microcapsules to engineer artificial cells and molecular robots.
A Nanoemulsion with A Porphyrin Shell for Cancer Theranostics
Authors: Hou Wenxiu , Lou Jenny W. H. , Bu Jiachuan , Chang Enling , Ding Lili , Valic Michael , Jeon Han Ho , Charron Danielle M. , Coolens Catherine , Cui Daxiang , Chen Juan , Zheng Gang 
Published: August 2019

AbstractA nanoemulsion with a porphyrin shell (NewPS) was created by the self‐assembly of porphyrin salt around an oil core. The NewPS system has excellent colloidal stability, is amenable to different porphyrin salts and oils, and is capable of co‐loading with chemotherapeutics. The porphyrin salt shell enables porphyrin‐dependent optical tunability. The NewPS consisting of pyropheophorbide a mono‐salt has a porphyrin shell of ordered J‐aggregates, which produced a narrow, red‐shifted Q‐band with increased absorbance. Upon nanostructure dissociation, the fluorescence and photodynamic reactivity of the porphyrin monomers are restored. The spectrally distinct photoacoustic imaging (at 715 nm by intact NewPS) and fluorescence increase (at 671 nm by disrupted NewPS) allow the monitoring of NewPS accumulation and disruption in mice bearing KB tumors to guide effective photodynamic therapy. Substituting the oil core with Lipiodol affords additional CT contrast, whereas loading paclitaxel into NewPS facilitates drug delivery.
Enabling Superior Electrochemical Properties for Highly Efficient Potassium Storage by Impregnating Ultrafine Sb Nanocrystals within Nanochannel‐Containing Carbon Nanofibers
Authors: Ge Xufang , Liu Shuhu , Qiao Man , Du Yichen , Li Yafei , Bao Jianchun , Zhou Xiaosi 
Published: August 2019

AbstractSb‐based nanocomposites are attractive anode materials for batteries as they exhibit large theoretical capacity and impressive working voltage. However, tardy potassium ion diffusion characteristics, unstable Sb/electrolyte interphase, and huge volume variation pose a challenge, hindering their practical use for potassium‐ion batteries (PIBs). Now, a simple robust strategy is presented for uniformly impregnating ultrasmall Sb nanocrystals within carbon nanofibers containing an array of hollow nanochannels (denoted u‐Sb@CNFs), resolving the issues above and yielding high‐performance PIBs. u‐Sb@CNFs can be directly employed as an anode, thereby dispensing with the need for conductive additives and binders. Such a judiciously crafted u‐Sb@CNF‐based anode renders a set of intriguing electrochemical properties, representing large charge capacity, unprecedented cycling stability, and outstanding rate performance. A reversible capacity of 225 mAh g−1 is retained after 2000 cycles at 1 A g−1.
A Fluorescent Kinase Inhibitor that Exhibits Diagnostic Changes in Emission upon Binding
Authors: Fleming Cassandra L. , Sandoz Patrick A. , Inghardt Tord , Önfelt Björn , Grøtli Morten , Andréasson Joakim 
Published: August 2019

AbstractThe development of a fluorescent LCK inhibitor that exhibits favourable solvatochromic properties upon binding the kinase is described. Fluorescent properties were realised through the inclusion of a prodan‐derived fluorophore into the pharmacophore of an ATP‐competitive kinase inhibitor. Fluorescence titration experiments demonstrate the solvatochromic properties of the inhibitor, in which dramatic increase in emission intensity and hypsochromic shift in emission maxima are clearly observed upon binding LCK. Microscopy experiments in cellular contexts together with flow cytometry show that the fluorescence intensity of the inhibitor correlates with the LCK concentration. Furthermore, multiphoton microscopy experiments demonstrate both the rapid cellular uptake of the inhibitor and that the two‐photon cross section of the inhibitor is amenable for excitation at 700 nm.
Synthesis and Utility of Neptunium(III) Hydrocarbyl Complex
Authors: Myers Alexander J. , Tarlton Michael L. , Kelley Steven P. , Lukens Wayne W. , Walensky Justin R. 
Published: August 2019

AbstractTo extend organoactinide chemistry beyond uranium, reported here is the first structurally characterized transuranic hydrocarbyl complex, Np[η4‐Me2NC(H)C6H5]3 (1), from reaction of NpCl4(DME)2 with four equivalents of K[Me2NC(H)C6H5]. Unlike the UIII species, the neptunium analogue can be used to access other NpIII complexes. The reaction of 1 with three equivalents of HE2C(2,6‐Mes2‐C6H3) (E=O, S) yields [(2,6‐Mes2‐C6H3)CE2]3Np(THF)2, maintaining the trivalent oxidation state.
Crystal structure of a NIR‐Emitting DNA‐Stabilized Ag16 Nanocluster
Authors: Cerretani Cecilia , Kanazawa Hiroki , Vosch Tom , Kondo Jiro 
Published: August 2019

AbstractDNA has been used as a scaffold to stabilize small, atomically monodisperse silver nanoclusters, which have attracted attention due to their intriguing photophysical properties. Herein, we describe the X‐ray crystal structure of a DNA‐encapsulated, near‐infrared emitting Ag16 nanocluster (DNA–Ag16NC). The asymmetric unit of the crystal contains two DNA–Ag16NCs and the crystal packing between the DNA–Ag16NCs is promoted by several interactions, such as two silver‐mediated base pairs between 3′‐terminal adenines, two phosphate–Ca2+–phosphate interactions, and π‐stacking between two neighboring thymines. Each Ag16NC is confined by two DNA decamers that take on a horse‐shoe‐like conformation and is almost fully shielded from the solvent environment. This structural insight will aid in the determination of the structure/photophysical property relationship for this class of emitters and opens up new research opportunities in fluorescence imaging and sensing using noble‐metal clusters.
Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor that Lacks the “9th Sulfur”
Authors: Jasniewski Andrew J. , Wilcoxen Jarett , Tanifuji Kazuki , Hedman Britt , Hodgson Keith O. , Britt R. David , Hu Yilin , Ribbe Markus W. 
Published: August 2019

AbstractNitrogenases catalyze the reduction of N2 to NH4+ at its cofactor site. Designated the M‐cluster, this [MoFe7S9C(R‐homocitrate)] cofactor is synthesized via the transformation of a [Fe4S4] cluster pair into an [Fe8S9C] precursor (designated the L‐cluster) prior to insertion of Mo and homocitrate. We report the characterization of an eight‐iron cofactor precursor (designated the L*‐cluster), which is proposed to have the composition [Fe8S8C] and lack the “9th sulfur” in the belt region of the L‐cluster. Our X‐ray absorption and electron spin echo envelope modulation (ESEEM) analyses strongly suggest that the L*‐cluster represents a structural homologue to the l‐cluster except for the missing belt sulfur. The absence of a belt sulfur from the L*‐cluster may prove beneficial for labeling the catalytically important belt region, which could in turn facilitate investigations into the reaction mechanism of nitrogenases.
Molecular Design Strategy for Ordered Mesoporous Stoichiometric Metal Oxide
Authors: Wang Changyao , Wan Xiaoyue , Duan Linlin , Zeng Peiyuan , Liu Liangliang , Guo Dingyi , Xia Yuan , Elzatahry Ahmed A. , Xia Yongyao , Li Wei , Zhao Dongyuan 
Published: August 2019

AbstractA molecular design strategy is used to construct ordered mesoporous Ti3+‐doped Li4Ti5O12 nanocrystal frameworks (OM‐Ti3+‐Li4Ti5O12) by the stoichiometric cationic coordination assembly process. Ti4+/Li+‐citrate chelate is designed as a new molecular precursor, in which the citrate can not only stoichiometrically coordinate Ti4+ with Li+ homogeneously at the atomic scale, but also interact strongly with the PEO segments in the Pluronic F127. These features make the co‐assembly and crystallization process more controllable, thus benefiting for the formation of the ordered mesostructures. The resultant OM‐Ti3+‐Li4Ti5O12 shows excellent rate (143 mAh g−1 at 30 C) and cycling performances (<0.005 % fading per cycle). This work could open a facile avenue to constructing stoichiometric ordered mesoporous oxides or minerals with highly crystalline frameworks.
Conformational Re‐engineering of Porphyrins as Receptors with Switchable N−H⋅⋅⋅X‐Type Binding Modes
Authors: Norvaiša Karolis , Flanagan Keith J. , Gibbons Dáire , Senge Mathias O. 
Published: August 2019

AbstractThe selectivity and functional variability of porphyrin cofactors are typically based on substrate binding of metalloporphyrins wherein the pyrrole nitrogen units only serve to chelate the metal ions. Yet, using the porphyrin inner core system for other functions is possible through conformational engineering. As a first step towards porphyrin “enzyme‐like” active centers, a structural and spectroscopic study of substrate binding to the inner core porphyrin system shows that a highly saddle‐distorted porphyrin with peripheral amino receptor groups (1, 2,3,7,8,12,13,17,18‐octaethyl‐5,10,15,20‐tetrakis(2‐aminophenyl)porphyrin) coordinates analytes in a switchable manner dependent on the acidity of the solution. The supramolecular ensemble exhibits exceptionally high affinity to and selectivity for the pyrophosphate anion (2.26±0.021)×109 m−1. 1H NMR spectroscopic studies provided insight into the likely mode of binding and the characterization of atropisomers, all four of which were also studied by X‐ray crystallography.