bluuebunny/crossref_metadata_2025 huggingface dataset:
Scale Effects on the Ballistic Penetration of Graphene Sheets
Authors: Bizao Rafael A. , Machado Leonardo D. , de Sousa Jose M. , Pugno Nicola M. , Galvao Douglas S.
Published: April 2018

Carbon nanostructures are promising ballistic protection materials, due to their low density and excellent mechanical properties. Recent experimental and computational investigations on the behavior of graphene under impact conditions revealed exceptional energy absorption properties as well. However, the reported numerical and experimental values differ by an order of magnitude. In this work, we combined numerical and analytical modeling to address this issue. In the numerical part, we employed reactive molecular dynamics to carry out ballistic tests on single, double, and triple-layered graphene sheets. We used velocity values within the range tested in experiments. Our numerical and the experimental results were used to determine parameters for a scaling law. We find that the specific penetration energy decreases as the number of layers (N) increases, from ∼15 MJ/kg for N = 1 to ∼0.9 MJ/kg for N = 350, for an impact velocity of 900 m/s. These values are in good agreement with simulations and experiments, within the entire range of N values for which data is presently available. Scale effects explain the apparent discrepancy between simulations and experiments.
An in vitro transepithelial migration assay to evaluate the role of neutrophils in Respiratory Syncytial Virus (RSV) induced epithelial damage
Authors: Deng Yu , Herbert Jenny A. , Smith Claire M. , Smyth Rosalind L.
Published: April 2018

Large numbers of neutrophils migrate into the lungs of children with severe Respiratory Syncytial Virus (RSV) disease. It is unclear how these cells contribute to viral clearance and recovery from infection or whether they contribute to disease pathology. We have developed a novelin vitromodel to study neutrophil migration through airway epithelial cells (AECs), the main cellular target of RSV infection. Our model reproduces a physiologically relevant cell polarity and directionality of neutrophil migration. Using this model, we found that RSV infected AECs induced rapid neutrophil transepithelial migration. We also detected increased AEC damage associated with RSV infection, with a further increase in epithelial cells shedding from the Transwell membrane following neutrophil migration. This was not observed in the mock infected controls. Neutrophils that migrated through the RSV infected AECs showed increased cell surface expression of CD11B and MPO compared to neutrophils that had not migrated. In conclusion, ourin vitroco-culture assay can be used to identify critical mechanisms that mediate epithelial cell damage and promote inflammation in children with severe RSV disease.
Author Correction: Identification and targeting of an FGFR fusion in a pediatric thalamic “central oligodendroglioma”
Authors: Linzey Joseph R. , Marini Bernard , McFadden Kathryn , Lorenzana Adonis , Mody Rajen , Robertson Patricia L. , Koschmann Carl
Published: April 2018

In the original version of this Article the Supplementary Information was missing. This file has now been added to the HTML version of this Article.
High-resolution reconstruction of the United States human population distribution, 1790 to 2010
Authors: Fang Yu , Jawitz James W.
Published: April 2018

Where do people live, and how has this changed over timescales of centuries? High-resolution spatial information on historical human population distribution is of great significance to understand human-environment interactions and their temporal dynamics. However, the complex relationship between population distribution and various influencing factors coupled with limited data availability make it a challenge to reconstruct human population distribution over timescales of centuries. This study generated 1-km decadal population maps for the conterminous US from 1790 to 2010 using parsimonious models based on natural suitability, socioeconomic desirability, and inhabitability. Five models of increasing complexity were evaluated. The models were validated with census tract and county subdivision population data in 2000 and were applied to generate five sets of 22 historical population maps from 1790–2010. Separating urban and rural areas and excluding non-inhabitable areas were the most important factors for improving the overall accuracy. The generated gridded population datasets and the production and validation methods are described here.
DataTri, a database of American triatomine species occurrence
Authors: Ceccarelli Soledad , Balsalobre Agustín , Medone Paula , Cano María Eugenia , Gurgel Gonçalves Rodrigo , Feliciangeli Dora , Vezzani Darío , Wisnivesky-Colli Cristina , Gorla David E , Marti Gerardo A , Rabinovich Jorge E
Published: April 2018

Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted to mammals - including humans - by insect vectors of the subfamily Triatominae. We present the results of a compilation of triatomine occurrence and complementary ecological data that represents the most complete, integrated and updated database (DataTri)available on triatomine species at a continental scale. This database was assembled by collecting the records of triatomine species published from 1904 to 2017, spanning all American countries with triatomine presence. A total of 21815 georeferenced records were obtained from published literature, personal fieldwork and data provided by colleagues. The data compiled includes 24 American countries, 14 genera and 135 species. From a taxonomic perspective, 67.33% of the records correspond to the genusTriatoma, 20.81% toPanstrongylus, 9.01% toRhodniusand the remaining 2.85% are distributed among the other 11 triatomine genera. We encourage usingDataTriinformation in various areas, especially to improve knowledge of the geographical distribution of triatomine species and its variations in time.
Visible light induced electropolymerization of suspended hydrogel bioscaffolds in a microfluidic chip
Authors: Li Pan , Yu Haibo , Liu Na , Wang Feifei , Lee Gwo-Bin , Wang Yuechao , Liu Lianqing , Li Wen Jung
Published: April 2018

3D net-like hydrogel scaffolds are fabricated via visible-light induced electropolymerization, which could be used to modulate 3D cell organization.
Tunnel injection from WS2 quantum dots to InGaN/GaN quantum wells
Authors: Santiago Svette Reina Merden , Caigas Septem P. , Lin Tzu-Neng , Yuan Chi-Tsu , Shen Ji-Lin , Chiu Ching-Hsueh , Kuo Hao-Chung
Published: April 2018

In this manuscript, an effective tunnel-injection structure, in which the WS2 quantum dots (QDs) act as the electron injector and the InGaN quantum wells (QWs) act as the light emitters, separated by GaN barriers.
Vacancy defect configurations in the metal–organic framework UiO-66: energetics and electronic structure
Authors: Svane Katrine L. , Bristow Jessica K. , Gale Julian D. , Walsh Aron
Published: April 2018

The energetics and electronic structure of defects in the metal–organic framework UiO-66 is investigated using density functional theory.
Coexisting order and disorder within a common 40-residue amyloid-β fibril structure in Alzheimer's disease brain tissue
Authors: Ghosh Ujjayini , Yau Wai-Ming , Tycko Robert
Published: April 2018

Only about half of the 40-residue amyloid-β sequence is structurally ordered in a common fibril structure from Alzheimer's disease brain.
Humidity-swing mechanism for CO2 capture from ambient air
Authors: Yang Hao , Singh Manmilan , Schaefer Jacob
Published: April 2018

The humidity-swing CO2 capture mechanism is revealed by solid-state NMR.
Spontaneous hybrids of graphene and carbon nanotube arrays at the liquid–gas interface for Li-ion battery anodes
Authors: Kim Hyeri , Kim Jongsoon , Jeong Hee-Sung , Kim Hyungsub , Lee Hoyeon , Ha Jae-Min , Choi Sung-Min , Kim Tae-Ho , Nah Yoon-Chae , Shin Tae Joo , Bang Joona , Satija Sushil K. , Koo Jaseung
Published: April 2018

We demonstrate that hybrid structures of graphene and single-walled carbon nanotubes (SWNTs) can be a promising anode material for Li-ion battery.
Decoding real space bonding descriptors in valence bond language
Authors: Martín Pendás A. , Francisco E.
Published: April 2018

Real space bonding descriptors are orbital invariant indices that can be obtained independently of the theoretical framework used to compute a given wavefunction.
Molecular simulations of self-assembling bio-inspired supramolecular systems and their connection to experiments
Authors: Frederix Pim W. J. M. , Patmanidis Ilias , Marrink Siewert J.
Published: April 2018

The self-assembly of bio-inspired supramolecular polymers can be unravelled using molecular dynamics simulations combined with experiments.
Multi-energy calibration as a strategy for elemental analysis of fertilizers by microwave-induced plasma optical emission spectrometry
Authors: Machado Raquel C. , Silva Ana Beatriz S. , Donati George L. , Nogueira Ana Rita A.
Published: April 2018

Multi-energy calibration was used to determine As, Ba, Cd, Cr, and Pb in fertilizers by MIP OES.
EPR and electrochemical interpretation of bispyrazolylacetate anchored Ni(ii) and Mn(ii) complexes: cytotoxicity and anti-proliferative activity towards human cancer cell lines
Authors: Das Kuheli , Beyene Belete B. , Datta Amitabha , Garribba Eugenio , Roma-Rodrigues Catarina , Silva Ana , Fernandes Alexandra R. , Hung Chen-Hsiung
Published: April 2018

The cytotoxicity and antiproliferative activity are carried out along with EPR and redox interpretation.
Esterquat herbicidal ionic liquids (HILs) with two different herbicides: evaluation of activity and phytotoxicity
Authors: Syguda Anna , Gielnik Anna , Borkowski Andrzej , Woźniak-Karczewska Marta , Parus Anna , Piechalak Aneta , Olejnik Anna , Marecik Roman , Ławniczak Łukasz , Chrzanowski Łukasz
Published: April 2018

Novel weed control agents in the form of herbicidal ionic liquids comprising two different herbicides as a cation and an anion.
A novel approach to sesquiterpenoid benzoxazole synthesis from marine sponges: nakijinols A, B and E–G
Authors: Takeda Yuki , Nakai Keiyo , Narita Koichi , Katoh Tadashi
Published: April 2018

Nakijinols A, B, E, F and G were efficiently synthesized via the ring closure of the N-(2-hydroxyphenyl)-formamide or -acetamide moiety.
ReductiveorthoC–H cyanoalkylation of aryl(heteroaryl) sulfoxides: a general approach to α-aryl(heteroaryl) nitriles
Authors: Luo Fan , Lu Yu , Hu Mengjie , Tian Junsong , Zhang Lei , Bao Wangzhen , Yan Chao , Huang Xin , Wang Zhi-Xiang , Peng Bo
Published: April 2018

A catalyst-free low-temperature cyanoalkylation has been developed as a general protocol for the synthesis of α-aryl(heteroaryl) nitriles.
Enhancing a clenbuterol immunosensor based on poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube performance using response surface methodology
Authors: Talib Nurul Ain A. , Salam Faridah , Yusof Nor Azah , Alang Ahmad Shahrul Ainliah , Azid Mohd Zulkhairi , Mirad Razali , Sulaiman Yusran
Published: April 2018

A clenbuterol immunosensor was developed with a poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube-modified screen-printed carbon electrode and optimized using response surface methodology.
Influence of surface modifications of a nanostructured implant on osseointegration capacity – preliminary in vivo study
Authors: Janeczek Maciej , Szymczyk Patrycja , Dobrzynski Maciej , Parulska Olga , Szymonowicz Maria , Kuropka Piotr , Rybak Zbigniew , Zywicka Boguslawa , Ziolkowski Grzegorz , Marycz Krzysztof , Chroszcz Aleksander , Skalec Aleksandra , Targonska Sara , Wiglusz Rafal J.
Published: April 2018

In response to the need for implant materials characterized by high biocompatibility a new type of nanostructured Ti6Al7Nb implants for osseous tissue regeneration have been fabricated.
One-pot sequential multicomponent reaction between in situ generated aldimines and succinaldehyde: facile synthesis of substituted pyrrole-3-carbaldehydes and applications towards medicinally important fused heterocycles
Authors: Singh Anoop , Mir Nisar A. , Choudhary Sachin , Singh Deepika , Sharma Preetika , Kant Rajni , Kumar Indresh
Published: April 2018

An efficient sequential multi-component method for the synthesis of N-arylpyrrole-3-carbaldehydes has been developed.
Ag3V2(PO4)2F3, a new compound obtained by Ag+/Na+ ion exchange into the Na3V2(PO4)2F3 framework
Authors: Bianchini M. , Lalère F. , Nguyen H. B. L. , Fauth F. , David R. , Suard E. , Croguennec L. , Masquelier C.
Published: April 2018

A new fluorophosphate polyanionic compound has been made by Ag+/Na+ ion exchange, leading to several potential technological applications.
Naphtho[1,2-b:4,3-b′]dithiophene-based hole transporting materials for high-performance perovskite solar cells: molecular engineering and opto-electronic properties
Authors: Cui Bin-Bin , Yang Ning , Shi Congbo , Yang Shuangshuang , Shao Jiang-Yang , Han Ying , Zhang Liuzhu , Zhang Qingshan , Zhong Yu-Wu , Chen Qi
Published: April 2018

Better planarity and conjugation of hole-transporting materials resulting in good charge extraction and transport efficiently improve the performance of perovskite solar cells.
A super-hydrophobic and electrically conductive nanofibrous membrane for a chemical vapor sensor
Authors: Gao Jiefeng , Wang Hao , Huang Xuewu , Hu Mingjun , Xue Huaiguo , Li Robert. K. Y.
Published: April 2018

A superhydrophobic and electrically conductive blend nanofibrous membrane was prepared for high performance chemical vapor sensors.
Journal of Materials Chemistry B Editor's choice web collection: “Seeing the unseen updated: advances in bioimaging”
Authors: Qu Xiaogang
Published: April 2018

Xiaogang Qu introduces a Journal of Materials Chemistry B Editor's choice web collection on advances in bioimaging (http://rsc.li/BioimagingAdvances).
Effects of a Tablet-Based Home Practice Program With Telepractice on Treatment Outcomes in Chronic Aphasia
Authors: Kurland Jacquie , Liu Anna , Stokes Polly
Published: April 2018

Purpose

The aim of this study was to determine if a tablet-based home practice program with weekly telepractice support could enable long-term maintenance of recent treatment gains and foster new language gains in poststroke aphasia.

Method

In a pre–post group study of home practice outcomes, 21 individuals with chronic aphasia were examined before and after a 6-month home practice phase and again at follow-up 4 months later. The main outcome measure studied was change in naming previously treated or untreated, practiced or unpracticed pictures of objects and actions. Individualized home practice programs were created in iBooks Author with semantic, phonemic, and orthographic cueing in pictures, words, and videos in order to facilitate naming of previously treated or untreated pictures.

Results

Home practice was effective for all participants with severity moderating treatment effects, such that individuals with the most severe aphasia made and maintained fewer gains. There was a negative relationship between the amount of training required for iPad proficiency and improvements on practiced and unpracticed pictures and a positive relationship between practice compliance and same improvements.

Conclusion

Unsupervised home practice with weekly video teleconferencing support is effective. This study demonstrates that even individuals with chronic severe aphasia, including those with no prior smart device or even computer experience, can attain independent proficiency to continue practicing and improving their language skills beyond therapy discharge. This could represent a low-cost therapy option for individuals without insurance coverage and/or those for whom mobility is an obstacle to obtaining traditional aphasia therapy.
Gaia Data Release 2
Authors: Riello M. , De Angeli F. , Evans D. W. , Busso G. , Hambly N. C. , Davidson M. , Burgess P. W. , Montegriffo P. , Osborne P. J. , Kewley A. , Carrasco J. M. , Fabricius C. , Jordi C. , Cacciari C. , van Leeuwen F. , Holland G.
Published: April 2018

Context. The second Gaia data release is based on 22 months of mission data with an average of 0.9 billion individual CCD observations per day. A data volume of this size and granularity requires a robust and reliable but still flexible system to achieve the demanding accuracy and precision constraints that Gaia is capable of delivering.

Aims. We aim to describe the input data, the treatment of blue photometer/red photometer (BP/RP) low-resolution spectra required to produce the integrated GBP and GRP fluxes, the process used to establish the internal Gaia photometric system, and finally, the generation of the mean source photometry from the calibrated epoch data for Gaia DR2.

Methods. The internal Gaia photometric system was initialised using an iterative process that is solely based on Gaia data. A set of calibrations was derived for the entire Gaia DR2 baseline and then used to produce the final mean source photometry. The photometric catalogue contains 2.5 billion sources comprised of three different grades depending on the availability of colour information and the procedure used to calibrate them: 1.5 billion gold, 144 million silver, and 0.9 billion bronze. These figures reflect the results of the photometric processing; the content of the data release will be different due to the validation and data quality filters applied during the catalogue preparation. The photometric processing pipeline, PhotPipe, implements all the processing and calibration workflows in terms of Map/Reduce jobs based on the Hadoop platform. This is the first example of a processing system for a large astrophysical survey project to make use of these technologies.

Results. The improvements in the generation of the integrated G–band fluxes, in the attitude modelling, in the cross-matching, and and in the identification of spurious detections led to a much cleaner input stream for the photometric processing. This, combined with the improvements in the definition of the internal photometric system and calibration flow, produced high-quality photometry. Hadoop proved to be an excellent platform choice for the implementation of PhotPipe in terms of overall performance, scalability, downtime, and manpower required for operations and maintenance.
La recherche agricole, vecteur de dynamiques collectives des territoires ruraux : l’Indication géographique « Vales da Uva Goethe » au Brésil
Authors: Cerdan Claire , Andrade Natalia , Lima da Silva Aparecido , Vieira Hamilton , Silva Edson , Le Guerroué Jean Louis
Published: April 2018

L’article analyse en quoi et comment la recherche peut être un vecteur de renforcement des dynamiques collectives des territoires par la méthode participative ImpresS (Impact des recherches au Sud). Celle-ci qualifie la façon dont la recherche accompagne les processus d’innovation et y contribue, et la façon dont elle renforce les actions collectives par la création de nouveaux espaces de dialogue et d’échanges entre les chercheurs et les parties prenantes d’un projet d’indication géographique (IG). La contribution de la recherche est analysée dans trois objets et échelles d’analyse : l’organisation porteuse de l’IG – l’association ProGoethe – ; le territoire de l’IG « Vales da Uva Goethe » ; et ses liens avec d’autres territoires impliqués dans des démarches de valorisation de produits locaux.
Recovery of magnetite from low grade banded magnetite quartzite (BMQ) ore
Authors: Tripathy Alok , Bagchi Subhankar , Rao Danda Srinivas , Nayak Bijaya Ketana , Rout Prashanta Kumar , Biswal Surendra Kumar
Published: April 2018

There has been a steady increase of iron ore demand in the last few decades. This growing demand could be countered by use of low grade iron ore after beneficiation. Banded iron formations (BIF) are one of the resources of such low grade iron ores. Banded magnetite quartzite (BMQ) is one such BIF and a source of iron phase mineral in the form of magnetite. In the present study a low grade BMQ ore containing around 25.47% Fe was beneficiated for recovery of magnetite. XRD study shows that quartz, magnetite, hematite, and goethite are the major minerals phases present in the low grade BMQ sample. Unit operations such as crushing, scrubbing, grinding, and magnetic separations were used for recovering magnetite. Based on the large scale beneficiation studies the process flowsheet has been developed for enrichment of magnetite. It was found that with the help of developed process flowsheet it is possible to enrich Fe value up to 65.14% in the concentrate with a yield of 24.59%.
Preventive effect of mesenchymal stem cell culture supernatant on luminal stricture after endoscopic submucosal dissection in the rectum of pigs
Authors: Tsuda Momoko , Ohnishi Shunsuke , Mizushima Takeshi , Hosono Hidetaka , Yamahara Kenichi , Ishikawa Marin , Abiko Satoshi , Katsurada Takehiko , Shimizu Yuichi , Sakamoto Naoya
Published: April 2018

Background Mesenchymal stem cells (MSCs) are valuable in regenerative medicine, and MSC culture supernatant (MSC-CS) reportedly inhibits inflammation and fibrosis. We investigated whether colorectal luminal stricture develops after circumferential endoscopic submucosal dissection (ESD) in the colorectum, and whether the development of luminal stricture could be prevented by using MSC-CS enema.

Methods In the first experiment, we performed circumferential ESD in the rectums or distal colons of pigs (n = 4 in each group). We sacrificed the pigs on Day 22 and measured the degree of luminal stricture. In the second experiment, we performed circumferential ESD in the rectums of pigs and administered an MSC-CS gel or a control gel enema after ESD for 4 days. We sacrificed the pigs on Day 8 (n = 3 in each group) or 22 (n = 3 in each group) to measure the degree of luminal stricture, and performed histological analysis.

Results Severe luminal stricture was observed in the rectum but not in the distal colon. Moreover, fiber accumulation in the submucosa and hypertrophy of the muscularis propria were observed in the rectum but not in the distal colon. The degree of luminal stricture in the rectum was significantly lower in the MSC-CS group than in the control group. Furthermore, MSC-CS attenuated myofibroblast activation and hypertrophy of the muscularis propria on Day 22, and reduced inflammatory cell infiltration on Day 8.

Conclusions Luminal stricture after ESD developed only in the rectum because of the difference in myofibroblast activation and fiber accumulation. In addition, MSC-CS enema prevented luminal stricture after ESD, possibly by inhibiting the inflammatory reaction and fibrosis.
Is Low-field NMR a Complementary Tool to GC-MS in Quality Control of Essential Oils? A Case Study: Patchouli Essential Oil
Authors: Krause Andre , Wu Yu , Tian Runtao , van Beek Teris
Published: April 2018

High-field NMR is an expensive and important quality control technique. In recent years, cheaper and simpler low-field NMR has become available as a new quality control technique. In this study, 60 MHz 1H-NMR was compared with GC-MS and refractometry for the detection of adulteration of essential oils, taking patchouli essential oil as a test case. Patchouli essential oil is frequently adulterated, even today. In total, 75 genuine patchouli essential oils, 10 commercial patchouli essential oils, 10 other essential oils, 17 adulterants, and 1 patchouli essential oil, spiked at 20% with those adulterants, were measured. Visual inspection of the NMR spectra allowed for easy detection of 14 adulterants, while gurjun and copaiba balsams proved difficult and one adulterant could not be detected. NMR spectra of 10 random essential oils differed not only strongly from patchouli essential oil but also from one another, suggesting that fingerprinting by low-field NMR is not limited to patchouli essential oil. Automated chemometric evaluation of NMR spectra was possible by similarity analysis (Mahalanobis distance) based on the integration from 0.1 – 8.1 ppm in 0.01 ppm increments. Good quality patchouli essential oils were recognised as well as 15 of 17 deliberate adulterations. Visual qualitative inspection by GC-MS allowed for the detection of all volatile adulterants. Nonvolatile adulterants, and all but one volatile adulterant, could be detected by semiquantitation. Different chemometric approaches showed satisfactory results. Similarity analyses were difficult with nonvolatile adulterants. Refractive index measurements could detect only 8 of 17 adulterants. Due to advantages such as simplicity, rapidity, reproducibility, and ability to detect nonvolatile adulterants, 60 MHz 1H-NMR is complimentary to GC-MS for quality control of essential oils.
Depression im Alter – Diagnostik, Pathophysiologie und therapeutische Strategien
Authors: Dafsari Forugh S. , Jessen Frank
Published: April 2018

Depressionen zählen zu den häufigsten psychischen Erkrankungen im höheren Lebensalter. Sie führen zu einer starken Inanspruchnahme von Gesundheitsleistungen und
gehen mit erhöhter Morbidität und Mortalität einher. Mit Blick auf den demografischen Wandel stellt die Altersdepression eine große Herausforderung der
alternden Gesellschaft dar. Der frühzeitigen Diagnostik und spezifischen Behandlung kommt eine besondere Bedeutung zu.
Nationale VersorgungsLeitlinie unspezifischer Kreuzschmerzn – Für Sie analysiert
Authors: Moers Stephanie
Published: April 2018

Ende 2017 erschien die zweite Auflage der Nationalen VersorgungsLeitlinie (NVL) unspezifischer Kreuzschmerz. Stephanie Moers hat die alte und neue Version analysiert. Ihr Fazit: Ein Schritt in die richtige Richtung mit Luft nach oben.
Nervenkompressionssyndrome – Wenn Nerven nerven
Authors: Paries Cornelia , Zander Andrea
Published: April 2018

Radfahrer, Liebespaare, Musiker – ein Kompressionssyndrom kann jeden treffen. Denn in Arm und Hand verlaufen wichtige Nerven auf engstem Raum. Werden sie komprimiert, können nachhaltige Nervenschäden entstehen. Mit Teil 1 unseres Refreshers frischen Sie Ihr anatomisches Wissen auf.
Landau problem with time dependent mass in time dependent electric and harmonic background fields
Authors: Lawson Latévi M. , Avossevou Gabriel Y. H.
Published: April 2018

The spectrum of a Hamiltonian describing the dynamics of a Landau particle with time-dependent mass and frequency undergoing the influence of a uniform time-dependent electric field is obtained. The configuration space wave function of the model is expressed in terms of the generalised Laguerre polynomials. To diagonalize the time-dependent Hamiltonian, we employ the Lewis-Riesenfeld method of invariants. To this end, we introduce a unitary transformation in the framework of the algebraic formalism to construct the invariant operator of the system and then to obtain the exact solution of the Hamiltonian. We recover the solutions of the ordinary Landau problem in the absence of the electric and harmonic fields for a constant particle mass.
Nonradiative recombination centers in GaAs:N δ-doped superlattice revealed by two-wavelength-excited photoluminescence
Authors: Dulal Haque Md. , Kamata Norihiko , Fukuda Takeshi , Honda Zentaro , Yagi Shuhei , Yaguchi Hiroyuki , Okada Yoshitaka
Published: April 2018

We use two-wavelength-excited photoluminescence (PL) to investigate nonradiative recombination (NRR) centers in GaAs:N δ-doped superlattice (SL) structures grown by molecular beam epitaxy. The change in photoluminescence (PL) intensity due to the superposition of below-gap excitation at energies of 0.75, 0.80, 0.92, and 0.95 eV and above-gap excitation at energies of 1.69 or 1.45 eV into the GaAs conduction band and the E− band implies the presence of NRR centers inside the GaAs:N δ-doped SL and/or GaAs layers. The change in PL intensity as a function of the photon number density of below-gap excitation is examined for both bands, which enables us to determine the distribution of NRR centers inside the GaAs:N δ-doped SL and GaAs layers. We propose recombination models to explain the experimental results. Defect-related parameters that give a qualitative insight into the samples are investigated systematically by fitting the rate equations to the experimental data.
Shock-induced reaction synthesis of cubic boron nitride
Authors: Beason M. T. , Pauls J. M. , Gunduz I. E. , Rouvimov S. , Manukyan K. V. , Matouš K. , Son S. F. , Mukasyan A.
Published: April 2018

Here, we report ultra-fast (0.1–5 μs) shock-induced reactions in the 3B-TiN system, leading to the direct synthesis of cubic boron nitride, which is extremely rare in nature and is the second hardest material known. Composite powders were produced through high-energy ball milling to provide intimate mixing and subsequently shocked using an explosive charge. High-resolution transmission electron microscopy and X-ray diffraction confirm the formation of nanocrystalline grains of c-BN produced during the metathetical reaction between boron and titanium nitride. Our results illustrate the possibility of rapid reactions enabled by high-energy ball milling possibly occurring in the solid state on incredibly short timescales. This process may provide a route for the discovery and fabrication of advanced compounds.
Surface tension of droplets and Tolman lengths of real substances and mixtures from density functional theory
Authors: Rehner Philipp , Gross Joachim
Published: April 2018

The curvature dependence of interfacial properties has been discussed extensively over the last decades. After Tolman published his work on the effect of droplet size on surface tension, where he introduced the interfacial property now known as Tolman length, several studies were performed with varying results. In recent years, however, some consensus has been reached about the sign and magnitude of the Tolman length of simple model fluids. In this work, we re-examine Tolman’s equation and how it relates the Tolman length to the surface tension and we apply non-local classical density functional theory (DFT) based on the perturbed chain statistical associating fluid theory (PC-SAFT) to characterize the curvature dependence of the surface tension of real fluids as well as mixtures. In order to obtain a simple expression for the surface tension, we use a first-order expansion of the Tolman length as a function of droplet radius Rs, as δ(Rs) = δ0 + δ1/Rs, and subsequently expand Tolman’s integral equation for the surface tension, whereby a second-order expansion is found to give excellent agreement with the DFT result. The radius-dependence of the surface tension of increasingly non-spherical substances is studied for n-alkanes, up to icosane. The infinite diameter Tolman length is approximately δ0 = −0.38 Å at low temperatures. For more strongly non-spherical substances and for temperatures approaching the critical point, however, the infinite diameter Tolman lengths δ0 turn positive. For mixtures, even if they contain similar molecules, the extrapolated Tolman length behaves strongly non-ideal, implying a qualitative change of the curvature behavior of the surface tension of the mixture.
Nonlinear optical transmittance of semiconductors in the presence of high-intensity radiation fields
Authors: Dong H. M. , Han F. W. , Duan Y. F. , Huang F. , Liu J. L.
Published: April 2018

We developed a systematic theoretical study of nonlinear optical properties of semiconductors. The eight-band k⋅p model and the energy-balance equation are employed to calculate the transmission and optical absorption coefficients in the presence of both the linear one-photon absorption and the nonlinear two-photon absorption (TPA) processes. A substantial reduction of the optical transmittance far below the band-gap can be observed under relatively high-intensity radiation fields due to the nonlinear TPA. The TPA-induced optical transmittance decreases with increasing intensity of the radiation fields. Our theoretical results are in line with those observed experimentally. The theoretical approach can be applied to understand the nonlinear optical properties of semiconductors under high-field conditions.
Glycine formation in CO2:CH4:NH3 ices induced by 0-70 eV electrons
Authors: Esmaili Sasan , Bass Andrew D. , Cloutier Pierre , Sanche Léon , Huels Michael A.
Published: April 2018

Glycine (Gly), the simplest amino-acid building-block of proteins, has been identified on icy dust grains in the interstellar medium, icy comets, and ice covered meteorites. These astrophysical ices contain simple molecules (e.g., CO2, H2O, CH4, HCN, and NH3) and are exposed to complex radiation fields, e.g., UV, γ, or X-rays, stellar/solar wind particles, or cosmic rays. While much current effort is focused on understanding the radiochemistry induced in these ices by high energy radiation, the effects of the abundant secondary low energy electrons (LEEs) it produces have been mostly assumed rather than studied. Here we present the results for the exposure of multilayer CO2:CH4:NH3 ice mixtures to 0-70 eV electrons under simulated astrophysical conditions. Mass selected temperature programmed desorption (TPD) of our electron irradiated films reveals multiple products, most notably intact glycine, which is supported by control measurements of both irradiated or un-irradiated binary mixture films, and un-irradiated CO2:CH4:NH3 ices spiked with Gly. The threshold of Gly formation by LEEs is near 9 eV, while the TPD analysis of Gly film growth allows us to determine the “quantum” yield for 70 eV electrons to be about 0.004 Gly per incident electron. Our results show that simple amino acids can be formed directly from simple molecular ingredients, none of which possess preformed C—C or C—N bonds, by the copious secondary LEEs that are generated by ionizing radiation in astrophysical ices.
Acoustic receptivity and transition modeling of Tollmien-Schlichting disturbances induced by distributed surface roughness
Authors: Raposo Henrique , Mughal Shahid , Ashworth Richard
Published: April 2018

Acoustic receptivity to Tollmien-Schlichting waves in the presence of surface roughness is investigated for a flat plate boundary layer using the time-harmonic incompressible linearized Navier-Stokes equations. It is shown to be an accurate and efficient means of predicting receptivity amplitudes and, therefore, to be more suitable for parametric investigations than other approaches with direct-numerical-simulation-like accuracy. Comparison with the literature provides strong evidence of the correctness of the approach, including the ability to quantify non-parallel flow effects. These effects are found to be small for the efficiency function over a wide range of frequencies and local Reynolds numbers. In the presence of a two-dimensional wavy-wall, non-parallel flow effects are quite significant, producing both wavenumber detuning and an increase in maximum amplitude. However, a smaller influence is observed when considering an oblique Tollmien-Schlichting wave. This is explained by considering the non-parallel effects on receptivity and on linear growth which may, under certain conditions, cancel each other out. Ultimately, we undertake a Monte Carlo type uncertainty quantification analysis with two-dimensional distributed random roughness. Its power spectral density (PSD) is assumed to follow a power law with an associated uncertainty following a probabilistic Gaussian distribution. The effects of the acoustic frequency over the mean amplitude of the generated two-dimensional Tollmien-Schlichting waves are studied. A strong dependence on the mean PSD shape is observed and discussed according to the basic resonance mechanisms leading to receptivity. The growth of Tollmien-Schlichting waves is predicted with non-linear parabolized stability equations computations to assess the effects of stochasticity in transition location.
On twisting type [N] ⊗ [N] Ricci flat complex spacetimes with two homothetic symmetries
Authors: Chudecki Adam , Przanowski Maciej
Published: April 2018

In this article, HH spaces of type [N] ⊗ [N] with twisting congruence of null geodesics defined by the 4-fold undotted and dotted Penrose spinors are investigated. It is assumed that these spaces admit two homothetic symmetries. The general form of the homothetic vector fields is found. New coordinates are introduced, which enable us to reduce the HH system of partial differential equations to one ordinary differential equation (ODE) on one holomorphic function. In a special case, this is a second-order ODE and its general solution is explicitly given. In the generic case, one gets rather involved fifth-order ODE.
Proton acceleration by a pair of successive ultraintense femtosecond laser pulses
Authors: Ferri J. , Senje L. , Dalui M. , Svensson K. , Aurand B. , Hansson M. , Persson A. , Lundh O. , Wahlström C.-G. , Gremillet L. , Siminos E. , DuBois T. C. , Yi L. , Martins J. L. , Fülöp T.
Published: April 2018

We investigate the target normal sheath acceleration of protons in thin aluminum targets irradiated at a relativistic intensity by two time-separated ultrashort (35 fs) laser pulses. When the full-energy laser pulse is temporally split into two identical half-energy pulses, and using target thicknesses of 3 and 6 μm, we observe experimentally that the second half-pulse boosts the maximum energy and charge of the proton beam produced by the first half-pulse for time delays below ∼0.6–1 ps. Using two-dimensional particle-in-cell simulations, we examine the variation of the proton energy spectra with respect to the time-delay between the two pulses. We demonstrate that the expansion of the target front surface caused by the first pulse significantly enhances the hot-electron generation by the second pulse arriving after a few hundreds of fs time delay. This enhancement, however, does not suffice to further accelerate the fastest protons driven by the first pulse once three-dimensional quenching effects have set in. This implies a limit to the maximum time delay that leads to proton energy enhancement, which we theoretically determine.
Monodispersed silk fibroin microdroplets for protein stabilization
Authors: Liu Qiang , Jiang Nan , Liu Dewen , Ying Guoliang , Shi Qiusheng , Yetisen Ali K. , Liu Haifeng , Fan Yubo
Published: April 2018

Low stability of globular protein droplets in emulsion significantly limits their applications in drug encapsulation, long-term storage, and controlled drug release. Here, a microfluidic flow-focusing device was utilized to synthesize horseradish peroxidase (HRP)-loaded silk fibroin microdroplets. The two immiscible streams of microfluidic flow-focusing were regenerated by silk fibroin solution and a mixture of 95 wt. % sunflower oil and 5 wt. % span 80 as the dispersed and continuous phases, respectively. In this study, the water-in-oil silk fibroin microdroplets were homogeneously produced by leveraging the discrete and periodic breakup of microdroplets and regulating the flow rates. Moreover, the result showed that the stability of encapsulated HRP in microdroplets was 25% higher than that of HRP after 6 weeks incubation. Thus, the microfluidic flow-focusing is a promising technique to form monodisperse microdroplets and maximize the stability of protein droplets.
Simple 2.5 GHz time-bin quantum key distribution
Authors: Boaron Alberto , Korzh Boris , Houlmann Raphael , Boso Gianluca , Rusca Davide , Gray Stuart , Li Ming-Jun , Nolan Daniel , Martin Anthony , Zbinden Hugo
Published: April 2018

We present a 2.5 GHz quantum key distribution setup with the emphasis on a simple experimental realization. It features a three-state time-bin protocol based on a pulsed diode laser and a single intensity modulator. Implementing an efficient one-decoy scheme and finite-key analysis, we achieve record breaking secret key rates of 1.5 kbps over 200 km of standard optical fibers.
In search of the Hohenberg-Kohn theorem
Authors: Lammert Paul E.
Published: April 2018

The Hohenberg-Kohn theorem, a cornerstone of electronic density functional theory, concerns uniqueness of external potentials yielding given ground densities of an N-body system. The problem is rigorously explored in a universe of three-dimensional Kato-class potentials, with emphasis on trade-offs between conditions on the density and conditions on the potential sufficient to ensure uniqueness. Sufficient conditions range from none on potentials coupled with everywhere strict positivity of the density to none on the density coupled with something a little weaker than local 3N/2-power integrability of the potential on a connected full-measure set. A second theme is localizability, that is, the possibility of uniqueness over subsets of R3 under less stringent conditions.
The effect of diethylene glycol on pollution from offshore gas platforms
Authors: Mannozzi Michela , Famiglini Giorgio , Cappiello Achille , Maggi Chiara , Palma Pierangela , Berducci Maria Teresa , Termopoli Veronica , Tornambè Andrea , Manfra Loredana
Published: April 2018

Environmental contextMarine mining activities are potential sources of environmental pollution. Diethylene glycol used in offshore platforms has been suspected to facilitate the release of toxic substances into the sea. The results obtained elucidate that this release is not significant for the metals examined here, apart from iron, nor for polycyclic aromatic hydrocarbons, even at very high diethylene glycol concentrations.
AbstractThe role of diethylene glycol (DEG) as a co-solvent for selected organic and inorganic pollutants adsorbed onto the particulate matter in produced formation water (PFW) from offshore gas platforms is thoroughly evaluated. Artificial seawater samples were spiked with certified sediments containing several polycyclic aromatic hydrocarbons (PAH) and metals. Aliquots (1 L) containing no DEG and DEG at 3500 and 5000 mg L−1 were kept in static and dynamic modes for 24 h before analysis to allow sufficient partitioning time between solid and liquid phases for the selected analytes. The Italian legislation on this matter sets 3500 mg L−1 as the highest concentration for DEG in PFW. In our experiments, concentrations equal to and above the set limit were chosen to enhance any possible co-solvent effect. Real PFW samples were also analysed, both with and without DEG. The analyses were conducted by using GC-MS for the PAH, and ICP-MS for the metals. A minor co-solvent effect was observed for low-molecular-weight PAH in the artificial seawater in static mode. Among metals, only iron showed an increase in solubility in the presence of DEG, demonstrating the co-solvent effect of DEG. The experiments in dynamic mode revealed no increase in the solubility of any other analytes in the liquid phase compared with static mode.
Scientific Society Journals: the Publications of the Astronomical Society of Australia
Authors: Lomb Nick
Published: April 2018

In the 1950s and 1960s the increased specialization of science led to the formation of discipline-based scientific societies. Some of these, among them the Astronomical Society of Australia, began their own refereed journals. The Publications of the Astronomical Society of Australia, which has now been continuously published by the Society for over 50 years, has undergone many changes in that time in response to the changes in the publication landscape. The method of production has advanced from manual to computer typesetting and from printed volumes to purely electronic publishing. The content of the journal has changed from short conference papers to formal research papers that now, under the impact of citation indices, face strict refereeing and are mixed with major invited review papers. Dedicated editors have maintained the journal despite a preference from many members to publish in better known overseas journals as well as strong opposition from within the society to the costs involved in maintaining a research journal.
Barking up the right tree: comparative use of arboreal and terrestrial artificial refuges to survey reptiles in temperate eucalypt woodlands
Authors: Michael Damian R. , Florance Daniel , Crane Mason , Blanchard Wade , Lindenmayer David B.
Published: April 2018

Context
Artificial refuges (cover boards) are a popular method to survey and monitor herpetofauna worldwide. However, one limitation of using artificial refuges in terrestrial environments is the low detection rates of arboreal species. Furthermore, destructive search techniques can damage critical microhabitat such as exfoliating rock or flaking bark of mature trees.

Aim
We tested a non-destructive, passive method of sampling arboreal reptiles in fragmented agricultural landscapes in south-eastern Australia.

Methods
We installed 84 artificial bark refuges consisting of strips of non-toxic, closed-cell foam attached to eucalypt trees in 13 patches of remnant vegetation. We used Bayesian statistics to compare differences in detection rates among artificial bark refuges, terrestrial artificial refuges and active searches of natural habitat over a 4-year period.

Key results
Active searches combined with terrestrial artificial refuges detected the highest number of reptile species, including several cryptic fossorial species. Artificial bark refuges detected, on average, 132 times more individuals of the arboreal southern marbled gecko, Christinus marmoratus, than did terrestrial refuges. Gecko abundance patterns were related to tree characteristics such as tree size, bark thickness and stand basal area, as well as survey year.

Conclusions
Traditional survey methods such as terrestrial cover boards, in combination with active searches of natural habitat, may significantly underestimate counts for arboreal gecko species.

Implications
Artificial bark refuges provide a cost-effective, non-destructive and durable method for surveying and monitoring arboreal reptiles in woodland environments over short to medium time frames. Foil-backed, closed-cell foam has broad application for use in spatial capture–recapture studies and long-term monitoring of arboreal reptiles. This method also may be effective for procuring records of threatened arboreal geckos or as a solution for providing temporary habitat in ecological restoration projects.
Spatial and temporal organization of cadherin in punctate adherens junctions
Authors: Indra Indrajyoti , Choi Jongho , Chen Chi-Shuo , Troyanovsky Regina B. , Shapiro Lawrence , Honig Barry , Troyanovsky Sergey M.
Published: April 2018

Significance

Adherens junctions (AJs) are major intercellular adhesive structures in vertebrates. Despite the critical role of AJs in tissue integrity and morphogenesis, the detailed organization of their key protein E-cadherin, inside and outside of AJs, remains controversial. Using superresolution microscopy approaches, we show that AJs can reach more than 1 μm in length and consist of tightly packed E-cadherin clusters with crystal-like density interspersed within sparser cadherin regions. No clusters were found outside of AJs. E-cadherin tracking showed that these crystal-like pAJ clusters are transient and their cadherin is reused for new clusters. Our results thus modify the classical view of AJs by depicting them as mosaics of cadherin clusters, whose short lifetimes enable stable overall morphology combined with rapid internal rearrangements.
Suppression of costimulation by human cytomegalovirus promotes evasion of cellular immune defenses
Authors: Wang Eddie C. Y. , Pjechova Mariana , Nightingale Katie , Vlahava Virginia-Maria , Patel Mihil , Ruckova Eva , Forbes Simone K. , Nobre Luis , Antrobus Robin , Roberts Dawn , Fielding Ceri A. , Seirafian Sepehr , Davies James , Murrell Isa , Lau Betty , Wilkie Gavin S. , Suárez Nicolás M. , Stanton Richard J. , Vojtesek Borivoj , Davison Andrew , Lehner Paul J. , Weekes Michael P. , Wilkinson Gavin W. G. , Tomasec Peter
Published: April 2018

Significance

Human cytomegalovirus (HCMV) is the major infectious cause of developmental disorders in babies due to its capacity to cross the placenta. HCMV is also a major pathogen in transplant recipients and HIV–AIDS patients. Despite inducing the strongest immune responses observed for any human pathogen, HCMV evades host defenses and persists for life. Herein, we report another viral stealth strategy. HCMV UL148 reduces surface expression of a key cell adhesion molecule (CD58), impairing the ability of NK and T cells to be activated by HCMV-infected cells. Our findings highlight a role for CD58 in recognition of HCMV-infected cells and may be relevant for development of future antiviral therapies.