bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective conversion of chitin to levulinic acid catalyzed by ionic liquids: distinctive effect of N-acetyl groups
Authors: Hou Wuxin , Zhao Qingyang , Liu Li
Published: October 2019

Selective and green conversion of chitin to levulinic acid has been realized by catalysis of ionic liquids up to a yield of 67.0%. Two-approach mechanism was proposed in the presence of H-bonding networks mainly contributed by the N-acetyl groups.
A 9,9′-bifluorenylidene derivative containing four 1,1-dicyanomethylene-3-indanone end-capped groups as an electron acceptor for organic photovoltaic cells
Authors: Yu Tianzhi , Yang Qianguang , Zhang Tong , Zhao Yuling , Wei Chengjin , Li Yanmei , Zhang Hui , Hu Dingqin
Published: October 2019

A non-fullerene receptor (BF-TDCI4) was successfully synthesized for organic photovoltaic cells, and the PCE of the device was 4.35%.
Ni–Cu/Al2O3 catalysts for the selective hydrogenation of acetylene: a study on catalytic performance and reaction mechanism
Authors: Hu Ningmeng , Yang Chenghuan , He Liang , Guan Qingqing , Miao Rongrong
Published: October 2019

Employing in situ DRIFTS spectra have successfully elucidated the reaction mechanism of Ni&Cu-NP/γ-Al2O3 catalyzed C2H2 semihydrogenation reaction.
Clustering of HClO4 with Brønsted (H2SO4, HClO4, HNO3) and Lewis acids BX3 (X = H, F, Cl, Br, OH): a DFT study
Authors: Valadbeigi Younes , Kurtén Theo
Published: October 2019

Interaction of HClO4 with Lewis and Brønsted acids leads to a variety of clusters exhibiting a wide range of acidity.
Correction: Graphene oxide–TiO2 composite: an efficient heterogeneous catalyst for the green synthesis of pyrazoles and pyridines
Authors: Kumari Shweta , Shekhar Amiya , Pathak Devendra D.
Published: October 2019

Correction for ‘Graphene oxide–TiO2 composite: an efficient heterogeneous catalyst for the green synthesis of pyrazoles and pyridines’ by Shweta Kumari et al., New J. Chem., 2016, 40, 5053–5060.
Frogspawn inspired hollow Fe3C@N–C as an efficient sulfur host for high-rate lithium–sulfur batteries
Authors: Zhang Huaiyue , Cui Hongtao , Li Jing , Liu Yuanyuan , Yang Yanzhao , Wang Meiri
Published: October 2019

A hollow Fe3C@N–C with frogspawn-like architecture was successfully constructed as an efficient sulfur host for high-rate and long-life lithium–sulfur batteries.
A high performance electroformed single-crystallite VO2 threshold switch
Authors: Zhou Xin , Gu Deen , Li Yatao , Qin Haoxin , Jiang Yadong , Xu Jimmy
Published: October 2019

We investigated the threshold switching characteristics of an electroformed single crystal VO2 channel, it exhibits a high Ion/Ioff ratio of 143, a steep turn-on voltage slope of <0.5 mV dec−1 and a fast switching speed of 23 ns.
Donor–acceptor type black phosphorus nanosheets covalently functionalized with a conjugated polymer for laser protection
Authors: Wang Kexin , Dong Ningning , Liu Zhiwei , Shi Makai , Zhang Bin , Wang Jun , Chen Yu
Published: October 2019

Donor–acceptor type black phosphorus nanosheets covalently functionalized with a conjugated polymer (PDBT-BP) exhibits excellent nonlinear optical and optical limiting performance.
Correction: Synthesis and optical properties of lead-free cesium germanium halide perovskite quantum rods
Authors: Chen Lin-Jer
Published: October 2019

Correction for ‘Synthesis and optical properties of lead-free cesium germanium halide perovskite quantum rods’ by Lin-Jer Chen, RSC Adv., 2018, 8, 18396–18399.
Influence of the heavy-atom effect on singlet fission: a study of platinum-bridged pentacene dimers
Authors: Basel Bettina S. , Young Ryan M. , Krzyaniak Matthew D. , Papadopoulos Ilias , Hetzer Constantin , Gao Yueze , La Porte Nathan T. , Phelan Brian T. , Clark Timothy , Tykwinski Rik R. , Wasielewski Michael R. , Guldi Dirk M.
Published: October 2019

Two platinum-bridged pentacene dimers undergo efficient singlet fission to form a correlated triplet pair (T1T1). The internal heavy-atom effect of the platinum allows for 1(T1T1)–3(T1T1) mixing leading to the formation of mainly (T1S0).
Two distinct nucleic acid binding surfaces of Cdc5 regulate development
Authors: Wang Chao , Li Mu , Li Guorui , Liu Xinsen , Zhao Wensheng , Yu Bin , Liu Junfeng , Yang Jun , Peng You-Liang
Published: October 2019

Cell division cycle 5 (Cdc5) is a highly conserved nucleic acid binding protein among eukaryotes and plays critical roles in development. Cdc5 can simultaneously bind to DNA and RNA by its N-terminal DNA-binding domain (DBD), but molecular mechanisms describing its nucleic acid recognition and the regulation of development through its nucleic acid binding remain unclear. Herein, we present a crystal structure of the N-terminal DBD of MoCdc5 (MoCdc5-DBD) from the rice blast fungus Magnaporthe oryzae. Residue K100 of MoCdc5 is on the periphery of a positively charged groove that is formed by K42, K45, R47, and N92 and is evolutionally conserved. Mutation of K100 significantly reduces the affinity of MoCdc5-DBD to a Cdc5-binding element but not to a conventional myeloblastosis (Myb) domain-binding element, suggesting that K100 is a key residue of the high binding affinity to Cdc5-binding element. Another conserved residue (R31) is located close to the U6 RNA in the structure of the spliceosome, and its mutation dramatically reduces the binding capacity of MoCdc5-DBD for U6 RNA. Importantly, mutations in these key residues, including R31, K42, and K100 in AtCDC5, an Arabidopsis thaliana ortholog of MoCdc5, greatly impair the functions of AtCDC5, resulting in pleiotropic development defects and reduced levels of primary microRNA transcripts. Taken together, our findings suggest that Cdc5-DBD binds nucleic acids with two distinct binding surfaces, one for DNA and another for RNA, which together contribute to establishing the regulation mechanism of Cdc5 on development through nucleic acid binding.
Allosteric changes in HDM2 by the ATM phosphomimetic S395D mutation: implications on HDM2 function
Authors: Uhrik Lukas , Wang Lixiao , Haronikova Lucia , Medina-Medina Ixaura , Rebolloso-Gomez Yolanda , Chen Sa , Vojtesek Borivoj , Fahraeus Robin , Hernychova Lenka , Olivares-Illana Vanesa
Published: October 2019

Allosteric changes imposed by post-translational modifications regulate and differentiate the functions of proteins with intrinsic disorder regions. HDM2 is a hub protein with a large interactome and with different cellular functions. It is best known for its regulation of the p53 tumour suppressor. Under normal cellular conditions, HDM2 ubiquitinates and degrades p53 by the 26S proteasome but after DNA damage, HDM2 switches from a negative to a positive regulator of p53 by binding to p53 mRNA to promote translation of the p53 mRNA. This change in activity is governed by the ataxia telangiectasia mutated kinase via phosphorylation on serine 395 and is mimicked by the S395D phosphomimetic mutant. Here we have used different approaches to show that this event is accompanied by a specific change in the HDM2 structure that affects the HDM2 interactome, such as the N-termini HDM2–p53 protein–protein interaction. These data will give a better understanding of how HDM2 switches from a negative to a positive regulator of p53 and gain new insights into the control of the HDM2 structure and its interactome under different cellular conditions and help identify interphases as potential targets for new drug developments.
Searching for the largest bound atoms in space
Authors: Emig K. L. , Salas P. , de Gasperin F. , Oonk J. B. R. , Toribio M. C. , Mechev A. P. , Röttgering H. J. A. , Tielens A. G. G. M.
Published: October 2019

Context. Radio recombination lines (RRLs) at frequencies ν <  250 MHz trace the cold, diffuse phase of the interstellar medium, and yet, RRLs have been largely unexplored outside of our Galaxy. Next-generation low-frequency interferometers such as LOFAR, MWA, and the future SKA will, with unprecedented sensitivity, resolution, and large fractional bandwidths, enable the exploration of the extragalactic RRL universe.

Aims. We describe methods used to (1) process LOFAR high band antenna (HBA) observations for RRL analysis, and (2) search spectra for RRLs blindly in redshift space.

Methods. We observed the radio quasar 3C 190 (z ≈ 1.2) with the LOFAR HBA. In reducing these data for spectroscopic analysis, we placed special emphasis on bandpass calibration. We devised cross-correlation techniques that utilize the unique frequency spacing between RRLs to significantly identify RRLs in a low-frequency spectrum. We demonstrate the utility of this method by applying it to existing low-frequency spectra of Cassiopeia A and M 82, and to the new observations of 3C 190.

Results. Radio recombination lines have been detected in the foreground of 3C 190 at z = 1.12355 (assuming a carbon origin) owing to the first detection of RRLs outside of the local universe (first reported in A&A, 622, A7). Toward the Galactic supernova remnant Cassiopeia A, we uncover three new detections: (1) stimulated Cϵ transitions (Δn = 5) for the first time at low radio frequencies, (2) Hα transitions at 64 MHz with a full width at half-maximum of 3.1 km s−1 the most narrow and one of the lowest frequency detections of hydrogen to date, and (3) Cα at vLSR ≈ 0 km s−1 in the frequency range 55–78 MHz for the first time. Additionally, we recover Cα, Cβ, Cγ, and Cδ from the −47 km s−1 and −38 km s−1 components. In the nearby starburst galaxy M 82, we do not find a significant feature. With previously used techniques, we reproduce the previously reported line properties.

Conclusions. RRLs have been blindly searched and successfully identified in Galactic (to high-order transitions) and extragalactic (to high redshift) observations with our spectral searching method. Our current searches for RRLs in LOFAR observations are limited to narrow (<100 km s−1) features, owing to the relatively small number of channels available for continuum estimation. Future strategies making use of a wider band (covering multiple LOFAR subbands) or designs with larger contiguous frequency chunks would aid calibration to deeper sensitivities and broader features.
The Kepler-11 system: evolution of the stellar high-energy emission and initial planetary atmospheric mass fractions
Authors: Kubyshkina D. , Fossati L. , Mustill A. J. , Cubillos P. E. , Davies M. B. , Erkaev N. V. , Johnstone C. P. , Kislyakova K. G. , Lammer H. , Lendl M. , Odert P.
Published: October 2019

The atmospheres of close-in planets are strongly influenced by mass loss driven by the high-energy (X-ray and extreme ultraviolet, EUV) irradiation of the host star, particularly during the early stages of evolution. We recently developed a framework to exploit this connection and enable us to recover the past evolution of the stellar high-energy emission from the present-day properties of its planets, if the latter retain some remnants of their primordial hydrogen-dominated atmospheres. Furthermore, the framework can also provide constraints on planetary initial atmospheric mass fractions. The constraints on the output parameters improve when more planets can be simultaneously analysed. This makes the Kepler-11 system, which hosts six planets with bulk densities between 0.66 and 2.45 g cm−3, an ideal target. Our results indicate that the star has likely evolved as a slow rotator (slower than 85% of the stars with similar masses), corresponding to a high-energy emission at 150 Myr of between 1 and 10 times that of the current Sun. We also constrain the initial atmospheric mass fractions for the planets, obtaining a lower limit of 4.1% for planet c, a range of 3.7–5.3% for planet d, a range of 11.1–14% for planet e, a range of 1–15.6% for planet f, and a range of 4.7–8.7% for planet g assuming a disc dispersal time of 1 Myr. For planet b, the range remains poorly constrained. Our framework also suggests slightly higher masses for planets b, c, and f than have been suggested based on transit timing variation measurements. We coupled our results with published planet atmosphere accretion models to obtain a temperature (at 0.25 AU, the location of planet f) and dispersal time of the protoplanetary disc of 550 K and 1 Myr, although these results may be affected by inconsistencies in the adopted system parameters. This work shows that our framework is capable of constraining important properties of planet formation models.
Zusammenhangsbegutachtung von Berufskrankheiten – die Rolle des Arztes
Authors: Nowak Dennis , Brandenburg Stephan
Published: October 2019

Not every disease which relates to work qualifies as an occupational disease according to German law. As there is a legal duty for doctors to report occupational diseases, doctors should know in which case a disease fulfils the requirements to be notified as occupational disease. This article gives an introduction to the legal framework applying to occupational diseases in Germany. It describes different types of occupational diseases and the requirements for a recognition. Expert opinions given by medical experts often are necessary to determine whether a disease can be recognized as occupational disease. Medical experts examine whether a disease was caused by a specific exposure at the workplace. Occupational diseases can lead to an impairment of earning capacity. Medical experts provide help with assessing such an impairment of earning capacity. This article provides useful information for medical experts as to the legal requirements for rendering medical expert opinions in court procedures, administrative procedures concerning occupational diseases.
Surgical treatment of septic subtendinous calcaneal bursitis in 2 cows
Authors: Kofler Johann , Erlacher Hannah , Pagliosa Geane
Published: October 2019

Two cows were referred to our clinic with moderate to severe hindlimb lameness due to infected wounds over the lateral and caudal aspect of tuber calcanei (TC) with regional swelling, consistent with septic subtendinous calcaneal bursitis. Ultrasonography (7.5 MHz linear probe) revealed fibrinous/fibrino-purulent inflammatory bursal effusions in both cows, complete rupture of the superficial digital flexor tendon and a small, circumscribed, irregular and rough bone contour of the TC in case 2. Radiography revealed physiological findings in case 1, whereas there were osteomyelitis and later bone sequestration in case 2. Treatment consisted of thorough wound debridement, establishing access to the bursa, removal of all exudate and fibrin, creation of additional drainage portals and meticulous lavage using sterile 0.9 % saline solution containing 0.1 % povidone-iodine performed under sedation and intravenous regional anesthesia. In case 2, the infected bone area of the TC was removed using a curette. However, a small bone sequestration developed from the TC 15 days later, which was associated with osteomyelitis. This was removed during a second surgical intervention. Systemic antimicrobial and anti-inflammatory medications were administered peri- and post-surgically and the bursae flushed repeatedly. The affected tarsi were covered with a modified Robert-Jones bandage or a fiberglass cast. Cows 1 and 2 were discharged from the clinic 25 and 27 days after initial surgery, respectively, displaying mild lameness. Both cows were alive, not lame and were in advanced stages of pregnancy at the time of manuscript submission 8 and 12 months later, respectively. This report describes in detail 2 severe cases of septic fibrino-purulent subtendinous calcaneal bursitis in cows that were successfully treated by surgical debridement and lavage under a practical anesthetic protocol, followed by proper wound management in the post-surgical period. These effective surgical procedures can be performed under field conditions given the availability of adequate equipment.
Kardiovaskuläres Risiko und chronische Entzündung
Authors: Milatz Florian
Published: October 2019

Aus postmortalen Untersuchungen ist bekannt, dass die Bildung atherosklerotischer Gefäßwandläsionen ihren Ursprung bereits im Kindesalter findet und in enger Beziehung zu bekannten kardiovaskulären Risikofaktoren Erwachsener steht. Um mit Hilfe der Regenerationspotenziale im Kindes- und Jugendalter eine beschleunigte Entwicklung atherosklerotischer Gefäßveränderungen zu verhindern, bedarf es einer frühzeitigen Diagnose und konsequenten Behandlung kardiovaskulärer Risikofaktoren. Heranwachsende mit einer Autoimmunerkrankung, wie z. B. einer juvenilen idiopathischen Arthritis (JIA), besitzen aufgrund chronischer Entzündungszustände, medikamentöser Therapien und metabolischer Veränderungen ein erhöhtes kardiovaskuläres Risiko. Zur Exposition nicht traditioneller Risiken gesellen sich traditionelle, verhaltensbasierte Risikofaktoren, deren Vermeidung im Rahmen chronischer Erkrankungen besondere Bedeutung beigemessen wird. Der aktuelle wissenschaftliche Datenbestand bei JIA unterstreicht aus kardiovaskulärer Sicht die Notwendigkeit von Lebensstilmodifikationen, einschließlich insbesondere der Vermeidung eines bewegungsarmen, durch niedrigen energetischen Aufwand gekennzeichneten Alltags.
Das moderne Management arterioviszeraler/-lumenaler Fisteln – eine Auswahl repräsentativer Fallkonstellationen
Authors: Barth Udo , Albrecht Roland , Halloul Zuhir , Meyer Frank
Published: October 2019

Einleitung Verbindungen abdomineller Arterien zu umgebenden luminären Organen, insbesondere bei triggernden Begleitumständen, sind seltene Erkrankungen, die jedoch im Rahmen der Verbreitung endovaskulärer Therapien und komplexer viszeral-/tumorchirurgischer Eingriffe mit nachfolgenden langwierigen adjuvanten Therapien zunehmend in Erscheinung treten.

Methode Narrative Übersicht auf Basis aktueller wissenschaftlicher Referenzen und eigener klinischer und operativer Erfahrungen im entscheidungstechnischen Herangehen, im taktischen Vorgehen, den operativen Möglichkeiten sowie deren perioperativem Management anhand von 5 repräsentativen Fallkomplexen.

Ergebnisse Ureteroarterielle Fisteln werden i. d. R. durch eine rezidivierende und intermittierende Makrohämaturie symptomatisch. Das Diagnostikum der Wahl stellt nach wie vor die Angiografie bei gleichzeitiger Möglichkeit der endovaskulären Therapie dar, die aufgrund der minimalen Invasivität, geringen Morbidität und Mortalität die offen chirurgischen Verfahren verdrängt hat. Aortoösophageale Fisteln können Folge von infektiösen und malignen Grunderkrankungen sowie offener und endovaskulärer Therapien an der Aorta sein. Das Mehrzeilen-Kontrast-CT des Thoraxes und Abdomens sowie die Gastroskopie haben in der Diagnostik Vorrang. Endovaskuläre Verfahren können nur als Bridging-Verfahren verstanden werden, allein der Prothesenausbau mit aortaler und gastrointestinaler Rekonstruktion gilt als kurativ. Aortoenterale Fisteln sind in sekundärer Form seltene Komplikationen der offenen und endovaskulären Aortenchirurgie. Das kontrastmittelverstärkte Mehrzeilen-CT weist eine hohe Sensitivität und Spezifität auf. Die offen chirurgische Therapie unterscheidet eine In-situ-Rekonstruktion von der extraanatomischen Rekonstruktion mit Aortenligatur. Die endovaskuläre Therapie ist Ausnahmefällen vorbehalten. Entzündliche Aneurysmen viszeraler Arterien können im Zusammenhang mit nahe gelegenen Entzündungsprozessen auftreten, wobei es sich meist um Pseudoaneurysmen handelt. Das geeignetste diagnostische Mittel besteht in der kontrastmittelverstärkten Dünnschicht-CT-Angiografie. Therapie der Wahl ist die endovaskuläre Ausschaltung mittels gecoverter Stents oder Embolisation.

Schlussfolgerung Arterioviszerale/-lumenale Fisteln sind in Pathogenese, prädisponierenden Faktoren und klinischen Symptomen ähnlich. Unterstützt durch ein modernes Mehrzeilen-CT mit Kontrastmittel ist eine schnelle Verifizierung und Therapieplanung möglich. Die Suche nach einem individuellen Therapieansatz im interdisziplinären Konsil sollte berücksichtigen, dass die endovaskulären/interventionellen Verfahren primär sicher und effektiv sind, während die offene chirurgische Sanierung meist einzig kurativ ist.
Safety and efficacy of submucosal tunneling endoscopic septum division for epiphrenic diverticula
Authors: Li Xuan , Zhang Weifeng , Yang Juliana , Wang Xiaoyong , Dang Yini , Hu Bin , Cai Qiang , Zhou Pinghong , Zhang Guoxin
Published: October 2019

Background Symptomatic epiphrenic diverticula are mostly treated with laparoscopic diverticulectomy. Our study aimed to demonstrate the safety and efficacy of submucosal tunneling endoscopic septum division (STESD) for treatment of symptomatic epiphrenic diverticula.

Methods Data from patients with epiphrenic diverticula who had undergone STESD were retrospectively reviewed. The parameters analyzed were the modified Eckardt score, total procedure time, length of hospital stay (LOS), number of clips used, adverse events, and patient satisfaction.

Results A total of eight patients (5 men; mean [standard deviation (SD)] age 66.25 [7.17] years) were enrolled in our study. The mean (SD) size of epiphrenic diverticula was 3.68 (1.59) cm. The mean (SD) procedure time was 52.87 (22.47) minutes, with a median number of six clips being applied. The modified Eckardt score significantly decreased post-procedure (P < 0.001). The mean (SD) LOS was 5.87 (0.83) days. No adverse events or symptom recurrences were reported.

Conclusion STESD is a safe and effective technique to be performed in the submucosal tunnel for the management of patients with epiphrenic diverticula.
Efficient Synthesis of 5-Trifluoromethylthio-1,2,3-Triazoles: One-Pot Multicomponent Reaction from Elemental Sulfur and TMSCF3
Authors: Zhang Lin-Lin , Li Meng-Tian , Shen Liang-Liang , Wu Qin-Pei
Published: October 2019

A sequential multistep reaction toward 5-trifluoromethyl­thio-1,2,3-triazoles has been established, starting from alkynes, organo­azides, S8, and (trifluoromethyl)trimethylsilane (TMSCF3). This reaction features mild conditions, easy operation, and readily available substrates.
Electrically active boron doping in the core of Si nanocrystals by planar inductively coupled plasma CVD
Authors: Patra Chandralina , Das Debajyoti
Published: October 2019

An improvement in the doping efficiency in p-type nc-Si:H, a two-phase structure consisting of Si-nanocrystallites embedded in an amorphous matrix, has been pursued via low-temperature, spontaneous, plasma processing of low-pressure and high-density SiH4 plasma with added B2H6, diluted in H2, in inductively coupled plasma CVD. With increased dopant incorporation, the gradually reduced overall crystallinity systematically dominates via an ultrananocrystalline component in the thermodynamically stable ⟨220⟩ orientation. The microstructure factor decreases continuously, and the bonded-H content of the network increases arbitrarily, with a significant fraction being associated with Si in an Si-H-Si plateletlike configuration. Effective doping by B atoms, mostly in fourfold coordination with Si in its nanocrystalline core, contributes to the rapid increase in conductivity of the doped p-nc-Si:H network, up to a moderate B2H6 flow rate. However, gradually enhanced doping by threefold coordinated electrically inactive B-atoms, mostly at the nanocrystalline grain boundary at a higher B2H6 flow rate, induces gross structural deviation in the degree of nanocrystallinity and reduces dark conductivity substantially. Further, the logarithmic magnitude of the conductivity prefactor (σ0) demonstrates the negative characteristic energy (EMN) in the Meyer–Neldel (MN) relation. The high density of charge carriers in the heavily doped configuration of the nc-Si network forms a deep and continuous band tail near the valence-band edge and induces subsequent narrowing of the bandgap as well as a shift of the Fermi level into the valence band. Degenerate-semiconductor type behavior has been accomplished in a heavily doped p-nc-Si:H network, demonstrating reverse MN characteristics in electrical transport.
A novel 3D entangled wavelet transformation and its properties
Authors: Chang Shoukang , Hu Liyun
Published: October 2019

Based on the quantum mechanics representation, we propose a novel 3D entangled wavelet transformation. This kind of three entangled state representation can be generated theoretically by using a two-cascaded beam splitter, which has the completeness and orthogonal property. Some properties of 3D WTs are discussed, including the Parseval theory of 3D WTs, its inverse formula, and the orthogonality of the mother wavelets in parameter space. In addition, the mother wavelet condition for the 3D WTs is also derived.
Gradient-index phononic crystals for highly dense flexural energy harvesting
Authors: Hyun Jaeyub , Choi Wonjae , Kim Miso
Published: October 2019

Gradient-index (GRIN) refers to a system where the refractive index changes spatially within a specific region. GRIN phononic crystals are capable of not only amplifying the magnitude of wave energies but also controlling the directional nature of the wave propagation, thus offering substantial benefits with regard to energy harvesting (EH) improvements. Here, we propose a systematic design method for GRIN phononic crystals which combine the two-dimensional Reissner–Mindlin plate model and a genetic algorithm for optimization. This design process allows us to design a GRIN phononic crystal with any arbitrary refractive index profile or complex shape of the unit cells. The experimentally verified focusing capability of the GRIN phononic crystals led to the realization of piezoelectric energy harvesting with a maximum areal power density value of up to 240.4 mW/m2, considerably outperforming the existing non-GRIN-based EH systems without direction controllability.
Shock-induced phase transition of g-C3N4 to a new C3N4 phase
Authors: Gao Xin , Yin Hao , Chen Pengwan , Liu Jianjun
Published: October 2019

In this study, phase transition of graphitic carbon nitride (g-C3N4) was investigated using the shockwave compression technique. Firstly, the shock Hugoniot data of g-C3N4 were obtained using a bore propellant gun and a light gas gun under impact velocities of 1.208–4.982 km/s, revealing one phase transition pressure of g-C3N4 at 22.4 GPa. Then, a series of shock recovery experiments was carried out with a pressure range of 17.0–62.1 GPa. The recovered samples were characterized by various techniques, including X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The measured d-values of the recovered samples were compared with those from the previous reported results, revealing a new carbon nitride phase synthesized by the shockwave compression technique. The new phase is indexed as a triclinic cell with a = 0.481 nm, b = 0.353 nm, c = 0.285 nm, α = 67.52°, β = 100.75°, γ = 106.47°, and Vcell = 0.043 nm3. EDX and XPS spectra reveal the existence of C and N elements with an atomic ratio of 0.754, also confirming the presence of a new C3N4 phase obtained via a g-C3N4 phase transition induced by shockwave compression with a pressure range of 29.3–62.1 GPa. These sample results are in good agreement with the shock Hugoniot data.
Rate of change of frequency under line contingencies in high voltage electric power networks with uncertainties
Authors: Delabays Robin , Tyloo Melvyn , Jacquod Philippe
Published: October 2019

In modern electric power networks with fast evolving operational conditions, assessing the impact of contingencies is becoming more and more crucial. Contingencies of interest can be roughly classified into nodal power disturbances and line faults. Despite their higher relevance, line contingencies have been significantly less investigated analytically than nodal disturbances. The main reason for this is that nodal power disturbances are additive perturbations, while line contingencies are multiplicative perturbations, which modify the interaction graph of the network. They are, therefore, significantly more challenging to tackle analytically. Here, we assess the direct impact of a line loss by means of the maximal Rate of Change of Frequency (RoCoF) incurred by the system. We show that the RoCoF depends on the initial power flow on the removed line and on the inertia of the bus where it is measured. We further derive analytical expressions for the expectation and variance of the maximal RoCoF, in terms of the expectations and variances of the power profile in the case of power systems with power uncertainties. This gives analytical tools to identify the most critical lines in an electric power grid.
The cantilever beam magnetometer for the measurement of electric field controlled magnetic property of ferromagnet/ferroelectrics heterostructures
Authors: Aireddy H. , Das A. K.
Published: October 2019

The Cantilever Beam Magnetometer (CBM) was designed, fabricated, and calibrated, and its ability to measure the electric field induced magnetization of ferromagnetic/ferroelectric heterostructures was demonstrated. Concisely, the working principle and the measurement system of the deflection of the magnetometer are conferred. The design of individual components and the assembly of the CBM setup are discussed in detail. Measurements were performed on the magnetic as well as the piezoelectric thin films and the ferromagnetic/ferroelectric heterostructures. The versatility of the developed CBM setup lies on the fact that the same instrument could be used to measure the electric field induced magnetization of the ferromagnetic/ferroelectric (FM/FE) heterostructures and the electroelastic effect of 1st order (converse piezoelectric) of piezoelectric materials at room temperature in addition to the conventional measurement of the magnetic properties [magnetization and magnetostriction (in-plane and out-of-plane)] of ferromagnetic materials as a function of magnetic field. This setup is simple in construction, is inexpensive to manufacture, is easy to operate, and has a sensitivity of 1 × 10−8 for magnetostriction and 2.7 × 10−9 Am2 for magnetization. Moreover, this CBM is suitable for research as well as teaching in postgraduate and doctorate levels.
Effect of different contents of nano-SiO2 particles on water diffusion behavior in insulating oil
Authors: Wang Qian , Zhang Shiling , Tian Wenxin , Liu Xiong , Du Dongyuan , Tang Chao
Published: October 2019

As an important component of the internal insulation system in a transformer, insulating oil will gradually age during the long-term operation of the transformer, which will lead to a degradation of its insulation performance. Previous studies have demonstrated that the addition of nano-SiO2 particles can effectively improve the breakdown voltage of insulating oil. Nano-SiO2 can effectively restrain the movement of water molecules in oil, which is one of the important reasons for nano-SiO2 particles to increase the breakdown voltage. The diffusion behaviors associated with different water contents in insulating oils with different nanoparticle contents are discussed herein, and the mechanisms at work in nano-SiO2 modified insulating oils are described on the molecular level. In this paper, simulations were based on naphthenic mineral oil, according to the mass ratio of the alkanes, which can fully represent the main physical and chemical properties of the insulating oil were employed in building the model, the mass-based percentages of water in the models were 1%, 3% and 5%, within each group, the models included an oil/water mixture containing nano-SiO2 which the mass-based percentages of nano were 1%, 2%, 3%, 4%, 5%. Prior to molecular dynamics simulations, the model was geometrically optimized, after which it was annealed and again geometrically optimized. Those systems that achieved equilibrium and energy convergence after this process could be employed for the molecular dynamics simulation. Through the analysis of the experimental results, the optimal concentration of nano-SiO2 particles for moisture binding in insulating oil was studied from a microscopic point of view. These results should assist in providing a theoretical foundation for further research regarding nano-modified insulating oils. In engineering applications, the content of nanometer SiO2 particles can be changed according to the moisture content at different times in the oil, so as to achieve the optimal binding of water, thus keeping the insulating oil with the best electrical performance.
Effect of dimensionless frequency on steady flows excited by fluid oscillation in wavy channel
Authors: Subbotin Stanislav , Kozlov Victor , Shiryaeva Mariya
Published: October 2019

Steady flows in a channel with wavy walls at the periodic pumping of the fluid are experimentally investigated. The channel is formed by two plates with sinusoidal relief located symmetrically relative to each other. The fluid oscillation results in excitation of steady flow in the channel cells. The transformation of the structure of steady flow with the dimensionless frequency of oscillation is systematically studied. In the limit of low dimensionless frequencies, when the oscillating flow in the entire volume of the channel is viscous, the steady flow in each channel cell has the form of a symmetric system of four transverse rolls. With an increase in the dimensionless frequency, the thickness of viscous boundary layers near the channel walls gradually decreases and the primary steady flow induces a secondary flow of the opposite rotation outside the boundary layers. With a further increase in the dimensionless frequency, the secondary flow fills the entire volume of the channel cells. It is found that the intensity of steady flow, which is determined by the pulsational Reynolds number, varies nonmonotonically with the dimensionless frequency. The transformation of the structure and intensity of steady flow with the dimensionless frequency in a wide range of frequency variation is determined. The general dependency of the steady flow intensity on dimensionless frequency is determined. It is found that in the limit of low frequencies, the velocity is mainly determined by the wall relief and poorly depends on the distance between the wavy walls of the channel.
Multi-level description of the vibronic dynamics of open quantum systems
Authors: Provazza Justin , Coker David F.
Published: October 2019

A new approximate coherent state path integral approach, which enables accurate and efficient dynamical treatment of model Hamiltonians that incorporate excited electronic states of multiple chromophores that are coupled to discrete high frequency harmonic vibrational modes, is presented. The approach is based on the mapping Hamiltonian formalism for the electronic states together with semiclassical coherent state expressions for the forward and backward propagators describing the quantum bath modes. The density matrix dynamics is propagated in the full coherent state basis for the electronic mapping and discrete vibrational mode oscillators using ensembles of weighted trajectories. An effective scheme for projecting the ensemble onto selected vibronic basis states is presented enabling the evolution of the reduced system density matrix to be monitored as well as exploring the importance of selected vibronic relaxation pathways in the multichromophore system dynamics. The approach is demonstrated for simple model Hamiltonians, and we show how this coherent state density matrix propagation approach for high frequency discrete harmonic vibrational modes can be combined with partial linearized density matrix propagation to treat an additional continuum bath of low frequency environmental modes that could, in principle, include anharmonicity.
Fundamental aspects of noise in analog-hardware neural networks
Authors: Semenova N. , Porte X. , Andreoli L. , Jacquot M. , Larger L. , Brunner D.
Published: October 2019

We study and analyze the fundamental aspects of noise propagation in recurrent as well as deep, multilayer networks. The motivation of our study is neural networks in analog hardware; yet, the methodology provides insight into networks in general. Considering noisy linear nodes, we investigate the signal-to-noise ratio at the network’s outputs, which determines the upper limit of computational precision. We consider additive and multiplicative noise, which can be purely local as well as correlated across populations of neurons. This covers the chief internal-perturbations of hardware networks, and noise amplitudes were obtained from a physically implemented neural network. Analytically derived descriptions agree exceptionally well with numerical data, enabling clear identification of the components critical for management and mitigation of noise. We find that analog neural networks are surprisingly robust, in particular, against noisy neurons. Their uncorrelated perturbations are almost fully suppressed, while correlated noise can accumulate. Our work identifies notoriously sensitive points while highlighting a surprising robustness of such computational systems.
Alkali-metal spin maser for non-destructive tests
Authors: Bevington P. , Gartman R. , Chalupczak W.
Published: October 2019

Radio-frequency atomic magnetometers offer attractive alternatives to standard detection methods in nondestructive testing, which are based on inductive measurements. We demonstrate a magnetometer in the so-called spin maser configuration, which addresses two important challenges of the technique: shifts in the radio frequency resonance position caused by magnetically permeable samples and the sensor bandwidth. Key properties of the self-oscillating sensor are presented in both a magnetically shielded and an open environment. Demonstration of defect detection via magnetic induction tomography in a ferromagnetic carbon steel sample is presented. The configuration discussed paves the way for a simple, rapid, and robust nondestructive material defect detection system based on an atomic magnetometer.
Nonintegrable spatial discrete nonlocal nonlinear schrödinger equation
Authors: Ji Jia-Liang , Xu Zong-Wei , Zhu Zuo-Nong
Published: October 2019

Integrable and nonintegrable discrete nonlinear Schrödinger equations (NLS) are significant models to describe many phenomena in physics. Recently, Ablowitz and Musslimani introduced a class of reverse space, reverse time, and reverse space-time nonlocal integrable equations, including the nonlocal NLS equation, nonlocal sine-Gordon equation, nonlocal Davey-Stewartson equation, etc. Moreover, the integrable nonlocal discrete NLS has been exactly solved by inverse scattering transform. In this paper, we study a nonintegrable discrete nonlocal NLS, which is a direct discrete version of the reverse space nonlocal NLS. By applying discrete Fourier transform and modified Neumann iteration, we present its stationary solutions numerically. The linear stability of the stationary solutions is examined. Finally, we study the Cauchy problem for the nonlocal NLS equation numerically and find some different and new properties on the numerical solutions comparing with the numerical solutions of the Cauchy problem for the NLS equation.
Vapor-phase nucleation of n-pentane, n-hexane, and n-heptane: Critical cluster properties
Authors: Ogunronbi Kehinde E. , Wyslouzil Barbara E.
Published: October 2019

The first and second nucleation theorems provide a way to determine the molecular content and excess internal energies of critical clusters, which rely solely on experimental nucleation rates measured at constant temperatures and supersaturations, respectively. Here, we report the size n* and excess internal energy Ex(n*) of n-pentane, n-hexane, and n-heptane critical clusters when particles form under the highly supersaturated conditions present in supersonic expansions. In summary, critical clusters contain from ∼2 to ∼11 molecules and exhibit the expected increase in the critical cluster size with increasing temperature and decreasing supersaturation. Surprisingly, the n* values for all three alkanes appear to lie along a single line when plotted as a function of supersaturation. Within the framework of the capillarity approximation, the excess internal energies determined for the n-heptane critical clusters formed under the low temperature (∼150 K) conditions in our supersonic nozzle are reasonably consistent with those determined under higher temperature (∼250 K) conditions in the thermal diffusion cloud chamber by Rudek et al. [J. Chem. Phys. 105, 4707 (1996)].
Electron spin relaxation in radical pairs: Beyond the Redfield approximation
Authors: Fay Thomas P. , Lindoy Lachlan P. , Manolopoulos David E.
Published: October 2019

Relaxation processes can have a large effect on the spin selective electron transfer reactions of radical pairs. These processes are often treated using phenomenological relaxation superoperators or with some model for the microscopic relaxation mechanism treated within Bloch-Redfield-Wangsness theory. Here, we demonstrate that an alternative perturbative relaxation theory, based on the Nakajima-Zwanzig equation, has certain advantages over Redfield theory. In particular, the Nakajima-Zwanzig equation does not suffer from the severe positivity problem of Redfield theory in the static disorder limit. Combining the Nakajima-Zwanzig approach consistently with the Schulten-Wolynes semiclassical method, we obtain an efficient method for modeling the spin dynamics of radical pairs containing many hyperfine-coupled nuclear spins. This is then used to investigate the spin-dependent electron transfer reactions and intersystem crossing of dimethyljulolidine-naphthalenediimide (DMJ-NDI) radical ion pairs. By comparing our simulations with experimental data, we find evidence for a field-independent contribution to the triplet quantum yields of these reactions which cannot be explained by electron spin relaxation alone.
On the determination of absorption cross section of colloidal lead halide perovskite quantum dots
Authors: Puthenpurayil Joseph , Cheng Oscar Hsu-Cheng , Qiao Tian , Rossi Daniel , Son Dong Hee
Published: October 2019

The absorption cross section of lead halide perovskite nanocrystals is important for understanding their photophysical properties, especially those depending on the density of photoexcited charge carriers. Despite its importance, there are large discrepancies among the reported absorption cross section values determined employing different methods. Here, we measured the absorption cross section of CsPbBr3 quantum dots (QDs) of varying sizes using elemental analysis and transient absorption (TA) saturation methods and compared with the previously reported values determined from elemental analysis and transient photoluminescence (PL) saturation methods. A careful comparison indicates that the reliable absorption cross section of lead halide perovskite QDs is obtained from both elemental analysis and TA saturation methods, while many previously reported values determined from the PL saturation method underestimate the absorption cross section.
Highly shear-thinning fluids are best for nutrient transport in small intestine
Authors: Gasparini Allison
Published: October 2019

Both Newtonian and non-Newtonian fluid behavior in elastic tubes influences tube deformation in a study with biomedical applications.
Stress granules regulate stress-induced paraspeckle assembly
Authors: An Haiyan , Tan Jing Tong , Shelkovnikova Tatyana A.
Published: October 2019

Eukaryotic cells contain a variety of RNA-protein macrocomplexes termed RNP granules. Different types of granules share multiple protein components; however, the crosstalk between spatially separated granules remains unaddressed. Paraspeckles and stress granules (SGs) are prototypical RNP granules localized exclusively in the nucleus and cytoplasm, respectively. Both granules are implicated in human diseases, such as amyotrophic lateral sclerosis. We characterized the composition of affinity-purified paraspeckle-like structures and found a significant overlap between the proteomes of paraspeckles and SGs. We further show that paraspeckle hyperassembly is typical for cells subjected to SG-inducing stresses. Using chemical and genetic disruption of SGs, we demonstrate that formation of microscopically visible SGs is required to trigger and maintain stress-induced paraspeckle assembly. Mechanistically, SGs may sequester negative regulators of paraspeckle formation, such as UBAP2L, alleviating their inhibitory effect on paraspeckles. Our study reveals a novel function for SGs as positive regulators of nuclear RNP granule assembly and suggests a role for disturbed SG-paraspeckle crosstalk in human disease.
Ultrafast optical currents in gapped graphene
Authors: Oliaei Motlagh S Azar , Nematollahi Fatemeh , Mitra Aranyo , Zafar Ahmal Jawad , Apalkov Vadym , Stockman Mark I
Published: October 2019

We theoretically study the interaction of ultrashort optical pulses with gapped graphene. Such a strong pulse results in a finite conduction band population and a corresponding electric current, both during and after the pulse. Since gapped graphene has broken inversion symmetry, it has an axial symmetry about the y -axis but not about the x-axis. We show that, in this case, if the linear pulse is polarized along the x-axis, the rectified electric current is generated in the y  direction. At the same time, the conduction band population distribution in the reciprocal space is symmetric about the x-axis. Thus, the rectified current in gapped graphene has an inter-band origin, while the intra-band contribution to the rectified current is zero.
Large spatial Schrödinger cat state using a levitated ferrimagnetic nanoparticle
Authors: Rahman A T M Anishur
Published: October 2019

The superposition principle is one of the main tenets of quantum mechanics. Despite its counter-intuitiveness, it has been experimentally verified using electrons, photons, atoms, and molecules. However, a similar experimental demonstration using a nano or a micro particle is non-existent. Here in this article, exploiting macroscopic quantum coherence and quantum tunneling, we propose an experiment using a levitated magnetic nanoparticle to demonstrate such an effect. It is shown that the spatial separation between the delocalized wavepackets of a 20 nm ferrimagnetic yttrium iron garnet (YIG) nanoparticle can be as large as 5 μm. We argue that, in addition to using for testing one of the most fundamental aspects of quantum mechanics, this scheme can simultaneously be used to test different modifications, such as wavefunction collapse models, to the standard quantum mechanics. Furthermore, we show that the spatial superposition of a core–shell structure, a YIG core and a non-magnetic silica shell, can be used to probe quantum gravity.
Heavy Neutrinos at Large Colliders
Authors: Soualah Rachik , Nasri Salah , Naseem Safa
Published: October 2019

In this work we discuss the state of the art of the heavy neutrinos at colliders. The neutrinos in the Standard Model (SM) are considered to be massless which is in contradiction with the evidence from the neutrino oscillations experiments. These cosmological observations established that at least two SM neutrinos have non-zero masses and that individual lepton number is violated. Therefore a strong conclusive first evidence of new physics caused by the neutrino mass mechanism is emerged. In this work we discuss the collider phenomenology of neutrino mass models at the existing (LHC) and next generation large colliders (FCC: ee, hh, eh, ILC and CePC) at different high synergies. It is naturally known that colliders are not sensitive to the SM light neutrinos; however the production of heavy neutrinos is very possible to be detected; giving rise to several signal processes which are categorised by different final state topologies according to theirs physics interests. We will present the state of the art of the heavy neutrinos generated with radiative neutrino mass models and their experimental searches; mainly for Majorana neutrino signals allowing for probing the nature of the Dark Matter candidates at high energy colliders. The focus will be on the well-motivated neutrino mass models which provide an elegant framework to explore new directions in Dark Matter phenomenology at the TeV scale and the future experimental prospects.