bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti-Toxoplasmaactivity of silver nanoparticles green synthesized withPhoenix dactyliferaandZiziphus spina-christiextracts which inhibits inflammation through liver regulation of cytokines in Balb/c mice
Authors: Alajmi Reem A. , AL-Megrin Wafa A. , Metwally Dina , AL-Subaie Hind , Altamrah Nourah , Barakat Ashraf M. , Abdel Moneim Ahmed E. , Al-Otaibi Tahani T. , El-Khadragy Manal
Published: April 2019

Toxoplasmosis constitutes a global infection caused by oblige intracellular apicomplexan protozoan parasite Toxoplasma gondii. Although often asymptomatic, infection can result in more severe, potentially life threatening symptoms particularly in immunocompromised individuals. The present study evaluated the anti-Toxoplasma effects in experimental animals of silver nanoparticles synthesized in combination with extracts of natural plants (Phoenix dactylifera and Ziziphus spina-christi) as an alternative method to standard sulfadiazine drug therapy. Liver functions estimated by and AST and ALT were significantly increased in T. gondii-infected mice compared with the control group as well as hepatic nitric oxide (NO), lipid peroxidation (LPO) levels and caused significant decrease in superoxide dismutase (SOD), catalase (CAT) and glutathione activities in the liver homogenates. Nanoparticles pretreatment prevented liver damage as determined by enzyme activity inhibition, in addition to significant inhibition of hepatic NO levels and significant elevation in liver SOD and CAT activities. Moreover, nanoparticle treatment significantly decreased hepatic LPO and NO concentrations and proinflammatory cytokines but significantly boosted the antioxidant enzyme activity of liver homogenate. In addition, histological examinations showed distinct alterations in the infected compared with untreated control groups. Conversely, nanoparticles pretreatment showed improvement in the histological features indicated by slight infiltration and fibrosis, minimal pleomorphism and less hepatocyte and degeneration. Furthermore, nanoparticles treatment induced a reduction in immunoreactivity to TGF-β and NF-κB in hepatic tissues. Therefore, the present study provides new insights into various natural plants that are used traditionally for the treatment of toxoplasmosis and other parasitic infections, which may be useful as alternative treatment option for T. gondii infections.
CircRASSF2 promotes laryngeal squamous cell carcinoma progression by regulating the miR-302b-3p/IGF-1R axis
Authors: Tian Linli , Cao Jing , Jiao Hui , Zhang Jiarui , Ren Xiuxia , Liu Xinyu , Liu Ming , Sun Yanan
Published: April 2019

Background: Circular RNAs (circRNAs) are a class of non-coding RNAs (ncRNAs) broadly expressed in cells of various species. However, the molecular mechanisms that link circRNAs with laryngeal squamous cell carcinoma (LSCC) are not well understood. In the present study, we attempted to provide novel basis for targeted therapy for LSCC from the aspect of circRNA–microRNA (miRNA)–mRNA interaction.

Methods: We investigated the expression of circRNAs in three paired LSCC tissues and adjacent non-tumor tissues by microarray analysis. Differentially expressed circRNAs were identified between LSCC tissues and non-cancerous matched tissues, including 527 up-regulated circRNAs and 414 down-regulated circRNAs. We focused on hsa_circ_0059354, which is located on chromosome 20 and derived from RASSF2, and thus we named it circRASSF2.

Results: circRASSF2 was found to be significantly up-regulated in LSCC tissues and LSCC cell lines compared with paired adjacent non-tumorous tissues and normal cells. Moreover, knockdown of circRASSF2 significantly inhibited cell proliferation and migration in vitro, which was blocked by miR-302b-3p inhibitor. Bioinformatics analysis predicted that there is a circRASSF2/miR-302b-3p/ insulin-like growth factor 1 receptor (IGF-1R) axis in LSCC progression. Dual-luciferase reporter system validated the direct interaction of circRASSF2, miR-302b-3p, and IGF-1R. Western blot verified that inhibition of circRASSF2 decreased IGF-1R expression. Furthermore, silencing circRASSF2 suppressed LSCC growth in vivo. Importantly, we demonstrated that circRASSF2 was up-regulated in serum exosomes from LSCC patients. Altogether, silencing circRASSF2 suppresses progression of LSCC by interacting with miR-302b-3p and decreasing inhibiting IGF-1R expression.

Conclusion: In conclusion, these data suggest that circRASSF2 is a central component linking circRNAs to progression of LSCC via an miR-302b-3p/IGF-1R axis.
Motor cable communication concept based on DSSS for inverter‐fed electric drives
Authors: Poluektov Anton , Pinomaa Antti , Ahola Jero , Kosonen Antti
Published: April 2019

Nowadays, electric motors and frequency converters have a great variety of applications. In motor feedback systems, communication is performed over separate sensor cables, which are notable for their high cost. Power line communication (PLC) over the motor cable is a promising and cost effective alternative. In this paper, a communication concept based on PLC and direct sequence spread spectrum (DSSS) channel access method is presented for motor cable communication. The channel characteristics and noise in the channel of a laboratory test setup are studied. Effect of the frequency converter output and switching frequencies on the channel noise are investigated. Capacitive and inductive signal coupling methods are evaluated and compared first theoretically by measurements and analysis of channel characteristics, and then practically by data transmission tests carried out in the laboratory test setup. Software‐defined radios (SDRs) are used as the data transmission devices for the communication concept evaluation. Concept's performance against variation of a signal‐to‐noise ratio (SNR) and switching frequency of the converter are evaluated. The concept applicability limits and optimal settings are presented. It can be stated that the concept provides a wider application range, than available solutions and can be effective for motor monitoring and speed data transmission.
Stochastic indexes for power distribution systems resilience analysis
Authors: Fanucchi Rodrigo Z. , Bessani Michel , Camillo Marcos H.M. , Soares Anderson da S. , London João B.A. , Desuó Luiz , Maciel Carlos D.
Published: April 2019

The resilience in critical infrastructures context indicates the capability to anticipate, absorb, resist and recover from an event or adversity. In a power distribution system, as the frequency of severe weather event increases, this characteristic becomes mandatory, considering the impact in the society when a blackout occurs. This study proposes the analysis of power distribution systems resilience through two stochastic resilience indexes. Given several simulated weather scenarios and several numbers of available repair crews, the resilience indexes estimate the probability of a waiting crew time greater than a threshold as well as for the impact in the total time to restore the entire distribution system. These indexes, together with a costs and losses estimation methodology help the utilities in the decision support process as it demonstrates how the number of available repair crews will impact in the restoration process and costs for each possible weather scenario. The result for a real Brazilian power distribution system indicates its feasibility and benefits for the utilities.
Compact broadband dual‐band circularly polarised antenna for universal UHF RFID handheld reader and GPS applications
Authors: Abdelrahim Waleed , Feng Quanyuan
Published: April 2019

This study introduces a simple, compact broadband dual‐band circularly polarised slot antenna suitable for the use in the compact universal ultra‐high frequency (UHF) radio‐frequency identification (RFID) reader devices and Global Positioning System (GPS) applications. The proposed antenna is fed using an open‐end coplanar waveguide with an inverted ‘L’ structure. To realise a broadband circular polarisation and good impedance matching, an inverted L‐shaped strip line is inserted adequately into a square slot at the right centre of the slot toward the slot centre. The experimental results demonstrate that the proposed antenna exhibits a 10 dB return loss bandwidth of 552 MHz (716–1268 MHz) and 3‐dB axial ratio (AR) bandwidth of 564 MHz (824–1388 MHz). Additionally, the antenna gains are 3.8 and 4.29 dBi throughout UHF RFID band and GPS band, respectively. The proposed antenna has a wide AR bandwidth, a compact size, and a simple structure. Furthermore, the proposed antenna is printed on one substrate layer with an overall size of 112 × 112 × 1.6 mm3, which makes it more practical for universal UHF RFID handheld readers and GPS applications.
General multi‐mode control method for optimising the efficiency of full bridge converter based on prominent control modes and transition points calculation
Authors: Ramezan Ghanbari Alireza , Raie Abolghasem
Published: April 2019

The theme of this article is to propose a general multi‐mode control method to optimise the efficiency of the full‐bridge converter based on prominent control modes for the whole range of load variations. This method selects the most efficient prominent control mode in each load sub‐range, including variable delay phase shift, fixed delay phase shift, pulse width modulation (PWM) and burst control while the load current varies in its entire range from full down to no load. In this regard, for the first time, three transition points between control modes are analytically determined based on full‐bridge converter power losses analysis. Determining transition points and load current sub‐ranges, being functions of converter parameters, is in fact the process of optimising the proposed method for the entire range of the load current in terms of four control modes. The accuracy of the analytically determined transition points and the optimal control mode selection over the load variations are justified by experimental results on digitally implemented proposed control method and full‐bridge converter.
Series‐connected single‐phase MMC for multi‐phase PMSG with DC grid
Authors: Rong Fei , Sun Wenlong , Zhou Shijia , Huang Shoudao
Published: April 2019

A topology for six series‐connected single‐phase modular multilevel converters (MMCs) for multi‐phase permanent‐magnet synchronous generator (PMSG) wind power systems is proposed to deliver wind power to a medium‐voltage DC (MVDC) grid. The AC side of each MMC is connected to one phase of the multi‐phase PMSG. The DC sides of the MMCs are connected in series to obtain a medium‐level DC voltage. The maximum power point tracking (MPPT) and grid‐connected control methods are discussed in detail. The high‐frequency voltage injection circuit is designed to suppress the voltage fluctuations of the sub‐module capacitor. Further, the nearest‐level and pulse width modulation (NL‐PWM) based on the sampling value is proposed to suppress the harmonics of the stator current. The proposed topology exhibits low costs, a high efficiency, and a high boost ratio without an additional step‐up DC/DC converter or transformer. The constructed simulation model verifies the validity of the proposed topology. Moreover, the experimental results are assessed with RT‐Lab.
Analysis, design and evaluation of a zero‐voltage‐switching non‐resonant converter for IPT applications
Authors: Marcos Alonso José , Wang Yijie , Yao Yousu , Xu Dianguo
Published: April 2019

This study presents the analysis, design and evaluation of a non‐resonant converter for inductive power transfer (IPT) applications that provides zero‐voltage‐switching operation. The thesis of this work is that in many low‐cost applications, compensation circuits used to provide resonant operation in IPT systems can be avoided, greatly simplifying the circuit and providing suitable operation and good efficiency. For this, available tools are a correct design of the converter in terms of switching frequency and output rectifier stage in order to achieve the required input–output characteristics. In order to achieve these goals, a thorough analysis of the non‐resonant IPT conversion system is carried out in this study, providing the required tools for a proper study and design of the system. Experimental results from a commercial IPT transmitter/receiver arrangement are provided in order to verify the theoretical study.
CCM and DCM analysis of ASC‐qZSIs
Authors: Dong Shuai , Zhang Qianfan
Published: April 2019

A novel active‐switched‐capacitor/inductor quasi‐Z‐source inverter (ASC‐qZSI) with an anti‐parallel switch which allows discontinuous conduction mode (DCM) was proposed. The analysis of the continuous conduction mode (CCM) and the DCM of the novel topology was also presented. Varying ASC‐qZSI inductances and load conditions were found to lead to the two operational modes. The CCM/DCM boundary condition was derived. Detailed analysis of the voltage regulation capability, inductor current ripples, switching devices stresses, and converter loss were carried on for CCM and DCM. Simulation and experimental verification have been presented for the theoretical findings.
Novel active clamped Y‐source network for improved voltage boosting
Authors: Reddivari Reddiprasad , Jena Debashisha
Published: April 2019

Y‐source impedance networks are one of the prominent two‐port networks for DC–DC and DC–AC applications with the higher boosting ability and reduced stress across the switching elements. However, the boosting ability of the Y‐source converter needs better magnetic coupling between the windings. The loosely coupled inductors cause high‐voltage spikes and poor voltage regulation. Use of highly rated switches or incorporation of the proper clamping circuit is essential to improve the performance Y‐source converter. It is always better to go with clamping/absorbing circuits instead of the selection of highly rated devices. Various passive and active clamping/absorbing circuits are introduced in literature to suppress the voltage spikes at the expense of higher component count. This article proposes a novel active clamped Y‐source impedance network and its family by adding one additional clamping diode to the existing type‐I improved Y‐source network. Compared to other Y‐source networks, the proposed networks absorb the voltage spikes with reduced passive component count and re‐utilise the absorbed energy to enhance the voltage gain in the presence of leakage inductance and winding equivalent series resistance. Finally, one of the proposed impedance networks, i.e. an active clamped Y‐source DC–DC converter, has been verified experimentally using a ferrite core.
Design of hybrid forward boost converter for renewable energy powered electric vehicle charging applications
Authors: Joseph Peter K. , Devaraj Elangovan
Published: April 2019

The grid‐connected electric vehicle charging stations are being integrated into renewable energy for preserving the conventional energy resources as well as to ensure sustainable development of the society. In addition to the effortless charging, the sudden demand variations in the grid can be met by the renewable energy storage system in the charging stations. The main challenge in this concept is the unstable nature of renewable energy. As the energy storage system of charging station is directly connected to the renewable energy source like a solar panel, according to the variable and deficient input power condition, the converter should supply a regulated output at the required magnitude. If a conventional converter is used for this purpose, the charging efficiency will be poor for higher gain conditions. This article presents a hybrid forward‐boost converter to overcome this challenge. By maintaining the power transfer efficiency higher, the gain can be varied to supply a regulated voltage, even for very low input conditions in this proposed topology. The maximum overall efficiency of 95% is achieved for a variable input condition of 30–50 V to provide an output voltage of 170 V. The concept is validated by implementing a 150 W hybrid converter.
Comparison of noise and chirp waveforms for radar target detection in clutter
Authors: Narayanan Ram M. , Allebach Joshua M. , Himed Braham
Published: April 2019

The use of random noise waveforms is investigated for radar surveillance and their performance is compared with traditional chirp waveforms based on the correlation and relative ratio of received to transmitted powers after reflections from simple targets and terrain. For simple shapes, the correlation of the two signals was similar in value and pattern with respect to the incidence angle. The reflection from terrain clutter gave smaller correlations for the noise waveform indicating that it may be less susceptible to false alarms. Additional simulations were performed for a hummer vehicle target using terrain clutter models to create receiver operating characteristic curves. It was found that the noise waveform performs as well as the chirp for cases of strong clutter response, and much better for cases of weak clutter response.
Field weakening control of a PM vehicle drive
Authors: Zbede Yaman , Apsley Judith
Published: April 2019

This paper develops a new field weakening method for an integrated permanent magnet synchronous machine vehicle drive. This method adopts both the DC‐link and the rotor speed as a feedback signals to generate the demagnetising current reference. This eliminates the effect of the rotor speed on the FW controller dynamics and ensures stable operation across the whole range of speeds. Mathematical analysis of the system is used to design the controller gains to achieve the desired dynamic response. A maximum torque per ampere (MTPA) strategy is included in the control design, with a linearised function to reduce the computational demand. Experimental results show stable and satisfactory operation at different speeds and load conditions. They also illustrate smooth transition between the MTPA operation and the FW operation when the rotor speed crosses base speed.
Suppression factor as evaluation criterion for wide‐frequency filtering equipment
Authors: Durna Emre , Ermiş Muammer
Published: April 2019

Here, a novel harmonic suppression performance criterion, namely suppression factor (SF), is suggested for the wide‐frequency power filtering equipment. Performances of single‐tuned passive filter, combination of passive filters tuned to various frequencies, shunt active power filter (APF), and a shunt hybrid active power filter (HAPF) topologies have been evaluated considering their SF values over a defined frequency range. Moreover, effect of the control method for the active filtering equipment on SF values is also analysed by comparing both theoretical and the experimental results. The frequency range of harmonics to be suppressed is chosen using the field measurements of Induction melting furnace (IMF) load, one of the most problematic loads in terms of interharmonics, and a field implemented HAPF system is used for the experimental verifications.
900 V GaN‐based sine‐wave inverters for three‐phase industrial applications
Authors: Mukherjee Nilanjan , Fuerst Johannes , Diepold Fabian , Aguilar Vega Fernando
Published: April 2019

GaN devices are gradually getting attention within the industry along with SiC as a potential wide bandgap device. At present, there are almost no high‐voltage GaN devices with voltage >650 V, which makes an inverter design difficult for a three‐phase input. To address this challenge to some extent, this study brings in for the first time a full 700 V DC‐link‐based three‐phase inverter‐fed high power density system using new 900 V GaN devices. The study also describes how a high switching frequency GaN device can benefit reducing filter size and cost, thereby offering an opportunity to integrate the filter within the inverter. This filter can also provide a sine‐wave output compared with the traditional pulse‐width modulator output. The article discusses multiple aspects of the design such as (a) switching behaviours of this new device, (b) filters, (c) power losses of the devices within the inverter through comprehensive simulation models and experimental investigations at 128 kHz. Some of the practical challenges are discussed, and the study claims that the GaN inverter for three‐phase applications is feasible with this new device.
DC–DC converter with a high step‐down ratio for water desalination applications
Authors: Pollock Richard C. , McNeill Neville , Holliday Derrick , Williams Barry W.
Published: April 2019

A single‐stage 600 : 1 ratio voltage step‐down dc–dc converter designed to produce a voltage of between 1 and 1.5 V from a rectified single/three‐phase AC supply, for application in a desalination process, is presented. A coupled‐inductor design is used, and a novel snubber circuit with energy recovery manages the effects of imperfect coupling (leakage) between the coupled windings. The circuit, which is bidirectional, allows for the power devices to be rated for either high current or high voltage. This presents significant cost and performance advantages compared to a conventional single‐stage buck converter where such a large step‐down ratio would require a small duty ratio and components with high ratings for both voltage and current: in this case, ratings of 1200 V to withstand input dc voltage switching, and 1000 A to deliver the output current, would be required.
Efficiency optimisation of an interleaved high step‐up converter
Authors: Ahmad Bilal , Kyyra Jorma , Martinez Wilmar
Published: April 2019

This study presents the performance comparison of two scenarios to obtain high voltage gain. A high step‐up converter (HSU) and a cascaded boost converter are chosen for this study. For analytical analysis, a loss model for both converters is developed on MATLAB. Gallium nitride‐ based prototypes of HSU and cascade boost converter provided the validation of the analytical analysis. Based on the theoretical evaluation and practical tests, efficiencies of both converters are expressed in terms of their voltage gain to find the optimal point of operation. Results showed that the cascaded boost converter is more efficient than the HSU converter at higher voltage gain values. However, the HSU converter has a higher energy density and lower switch voltage stress than those of the cascaded boost converter.
FEA model study of spectral signature patterns of PM demagnetisation faults in synchronous PM machines
Authors: Melecio Juan I. , Djurović Siniša , Schofield Nigel
Published: April 2019

This work reports a finite element analysis (FEA) model study of the stator current spectra of a commercial permanent magnet (PM) AC machine operating with rotor PM demagnetisation faults. A range of PM uniform and local demagnetisation fault scenarios at different severity conditions are examined. The aim of this study is to investigate the extent to which different modes of PM demagnetisation could be distinguished by inspecting the spectral signature patterns these generate in the stator current signal. To this end, a generalised mathematical characterisation of PM fault spectral signature in the stator current is examined and a 2D FEA software used to establish a model of the studied PM machine design. The FEA model was employed to predict the current signal spectral signature patterns of a range of different PM demagnetisation faults. These are then correlated with those arising from the derived expressions to examine whether the predicted and expected spectral trends are in agreement and whether their observation as the potential to provide diagnostic information.
Gate‐driver circuit with a variable supply voltage to influence the switching losses
Authors: Ruthardt Johannes , Hermann Chris , Wölfle Julian , Fischer Manuel , Roth‐Stielow Jörg
Published: April 2019

The lifetime of semiconductor devices used in power electronics depends on the junction temperature. With a suitable junction temperature control system, the lifetime of semiconductor devices is extended. These control systems require a possibility to influence the power losses of the semiconductor devices and therefore the junction temperature. The proposed gate‐driver circuit has a variable supply voltage in order to influence the switching speed of the semiconductor devices. This affects the switching losses. In addition, the adjustable switching speed can be used to prevent voltage overshoots during the switching transition or to decrease electromagnetic emission. The main advantage of this gate‐driver circuit is its simple structure. This study focuses on the switching losses.
Frequency and operational characteristics of an ultra‐lightweight machine converting energy by magnetic resonance coupling
Authors: Sakai Kazuto , Takishima Kenta
Published: April 2019

Electric aircrafts capable of moving in three dimensions cause creation of new industries and applications in society. Also, electric aircrafts operate on minimal energy with low emissions. However, an electric aircraft must be ultra‐lightweight. To produce an ultra‐lightweight machine for electric aircrafts, the authors proposed a machine in which electrical energy is converted between the stator and rotor through magnetic resonance coupling (MRC). This action causes electromagnetic resonance between the multiphase windings of the stator and rotor. Electromagnetic resonance coupling technology allows electrical machines to convert energy without a magnetic core, thereby allowing the production of ultra‐lightweight machines. In this study, authors describe a machine with three‐phase windings based on MRC and discuss its operating principles and the basic characteristics induced by MRC. A model of this MRC machine was subjected to magnetic analyses to assess its rotational energy conversion in a rotating machine and to understand its basic characteristics. Authors’ results confirmed that MRC machines without a magnetic core could convert magnetic energy between the stator and rotor and produce sufficient starting torque and power at a power factor of 1.0. Furthermore, the machine was highly efficient, and its torque increased with resonant frequency.
Spectral meta-moments reveal hidden signatures of vortex pulses
Authors: Liebmann Max , Treffer Alexander , Bock Martin , Seiler Thomas , Jahns Jürgen , Elsaesser Thomas , Grunwald Ruediger
Published: April 2019

Ultrashort vortex pulses possess specific spatio-spectral signatures due to Gouy phase shift. Helical movement of anomalies around the phase singularity was found which is referred to as spectral Gouy rotation. The analysis of spectral moments allows for identifying related characteristic patterns even in weakly modulated spectral maps. Radial meta-moments from polar projections deliver information on global spectral gradients and oscillatory behavior. The particular mathematical tools could also be applied to other fields of ultrafast spectroscopy.
Tracing the phase of focused broadband laser pulses
Authors: Hoff Dominik , Krüger Michael , Maisenbacher Lothar , Sayler A. Max , Hommelhoff Peter , Paulus Gerhard G.
Published: April 2019

We present a three-dimensional measurement of the local focal phase in a focused broadband Gaussian laser beam and find strong deviations from the commonly assumed Gouy phase, with wide ramifications for ultrafast physics.
Direct measurement of intense sub-4-fs pulses in a gas target by 3rd-harmonic dispersion-scan
Authors: Crespo Helder , Canhota Miguel , Witting Tobias , Tisch John
Published: April 2019

We demonstrate the on-target temporal characterization of sub-4-fs pulses by third-harmonic dispersion-scan, using a minimal in-line setup where a gas target optimized for high-harmonic generation doubles as nonlinear medium, obtaining excellent agreement with independent SEA-F-SPIDER measurements.
Quasi-phase-matched high harmonic generation in structured plasmas
Authors: Wöstmann Michael , Splitthoff Lukas , Zacharias Helmut
Published: April 2019

Structured plasmas are employed in order to realize the quasi-phase-matched generation of high harmonics. The plasma originates from laser ablated solids leading to the appearance of multiple separated jets. By altering the shape of the solid the dimensions of the plasma structure are easily optimized. Combining optimal jet widths and spacing the maximum enhancement of the harmonic intensity by a factor of 16 is observed after four plasma jets.
Antenna-enhanced high harmonic generation in a wide-bandgap semiconductor ZnO
Authors: Imasaka Kotaro , Kaji Tomohiro , Shimura Tsutomu , Ashihara Satoshi
Published: April 2019

We demonstrate high harmonic generation (HHG) into deep-UV range in a ZnO single crystal with resonant nanoantennas. Non-perturbative HHG is successfully induced by optical excitation of as low as 20 GW/cm2. The spectral selection rule is found to reflect crystal symmetry, suggesting the possibility of nano-scaled EUV sources and band-structure reconstruction.
High-order harmonic generation traces ultrafast coherent phonon dynamics in ZnO
Authors: Hollinger Richard , Shumakova Valentina , Pugžlys Audrius , Baltuška Andrius , Khujanov Sherzod , Spielmann Christian , Kartashov Daniil
Published: April 2019

Ultrafast coherent phonon dynamics in ZnO is studied via high-order harmonic generation by intense mid-IR laser pulses. We show, the phonon dynamic is very different after excitation in the tunnel and multiphoton regime.
Infrared pre-excitation grants isotopomer-specific photochemistry
Authors: Kern-Michler Daniela , Neumann Carsten , Mielke Nicole , Luuk J. G. W. van Wilderen , Reinfelds Matiss , von Cosel Jan , Santoro Fabrizio , Heckel Alexander , Burghardt Irene , Bredenbeck Jens
Published: April 2019

Species-selective photochemistry is often hampered by overlapping UV-Vis spectra. We overcome this long-standing problem by combined vibrational and electronic excitation as demonstrated by isotopomer selection. The influence of various factors on selectivity is discussed.
Towards broadband two-Dimensional electronic spectroscopy with ~8 fs phase-locked pulses at 400 nm
Authors: Agathangelou Damianos , El-Khoury Youssef , Brazard Johanna , Crégut Olivier , Haacke Stefan , Cerullo Giulio , Léonard Jérémie
Published: April 2019

We introduce a two-dimensional spectroscopy setup based on a pair of near-UV-blue (360 - 430 nm), 8.4-fs, phase-locked, collinear excitation pulses and a nearly collinear UV-Vis supercontinuum probe pulse.
Spatially resolved coherent 2D fluorescence spectroscopy within a high-NA microscope
Authors: Li Donghai , Nuss Matthias , Goetz Sebastian , Kolb Verena , Pflaum Jens , Trovatello Chiara , Cerullo Giulio , Brixner Tobias
Published: April 2019

We have developed coherent two-dimensional (2D) fluorescence micro-spectroscopy which probes the nonlinear optical response at surfaces via fluorescence detection with sub-micron spatial resolution. This enables the investigation of microscopic variations in laterally heterogeneous film samples which are of interests for sub-wavelength opto-electronic devices.
Soft-mode driven dynamics in ferroelectrics -new insight from ultrafast terahertz and x-ray experiments
Authors: Elsaesser Thomas , Folpini Giulia , Somma Carmine , Reimann Klaus , Holtz Marcel , Hernandez Salvador Antonio-Andres , Hauf Christoph , Woerner Michael
Published: April 2019

The coupled lattice and charge dynamics connected with soft-mode excitations are mapped by nonlinear terahertz spectroscopy and ultrafast x-ray diffraction. Sub-picometer lattice displacements induce electron relocations over 100 pm in polycrystaline aspirin and ferroelectric ammonium sulfate (AS). In AS, the electron motions induce a macroscopic polarization switching.
Amorphization in crystalline tellurium by femtosecond pulses
Authors: Cheng Yu-Hsiang , Teitelbaum Samuel , Gao Frank , Nelson Keith
Published: April 2019

Crystalline tellurium undergoes amorphization after irradiation with strong femtosecond pulses. Steady-state reflectivity and single-shot transient reflectivity studies suggest the amorphization is due to thermal melting rather than non-thermal switching.
Two-dimensional electronic spectroscopy of graphene nanoribbons in organic solution
Authors: Nagahara Tetsuhiko , Ganzer Lucia , Franco V. A. Camargo , Huang Yinjuan , Xu Fugui , Mai Yiyong , Cerullo Giulio , Feng Xinliang
Published: April 2019

We unravel the electronic structure of graphene nanoribbons in solution using two-dimensional electronic spectroscopy. We identify different excitons, their vibrational couplings and find that exciton diffusion or relaxation among the exiton sublevels takes place in ~300 fs.
Theoretical study of the ultrashort dynamics in graphene after fs-laser excitation
Authors: Sergej Krylow , Martin E. Garcia
Published: April 2019

We report on the calculation of the full dynamics of graphene after ultrafast laser excitation using ab-initio molecular dynamics simulations. Our calculations show a biexponential decay of the (100) and (110) Bragg peaks in time, similar to experimental results. Furthermore, we calculate the time-evolution of the phonon energies averaged over sets of phonons, chosen by their phonon frequencies. Our results suggest that the fast decay time can be accounted by phonon-phonon interactions rather than the generation of SCOPs. The slower decay time is governed by the equilibration of the system with low frequency phonon modes.
Electron Wave Functions in Heteronano-structures Control the Electron Transfer Dynamics
Authors: Dworak Lars , Roth Sina , Wachtveitl Josef
Published: April 2019

Electron transfer dynamics in CdTe/CdSe and CdSe/CdS core/shell heteronanostructures decorated with molecular acceptors are determined via transient absorption spectroscopy. The CdSe shell accelerates the electron transfer whereas the CdS shell leads to a retardation.
Temporal dynamics of the coulomb screening in single layer MoS2
Authors: Trovatello Chiara , Dal Conte Stefano , Boris Nick , Yao Kaiyuan , Scotognella Francesco , Kriegel Ilka , Borrego Varillas Rocio , Ganzer Lucia , Schuck P. James , Cerullo Giulio
Published: April 2019

We measure exciton dynamics in single-layer MoS2 with unprecedented temporal resolution and we directly extract the characteristic time-scale for the Coulomb screening dynamics, which ranges between 15 and 35 fs.
Ultrafast dynamics of a bi-stable azopyridine Ni-porphyrin spin switch after photoexcitation in the porphyrin B-bands
Authors: Megow Sebastian , Bahrenburg Julia , Dittner Mark , Kohly Birthe , Gripp Joachim , Dommaschk Marcel , Schütt Christian , Herges Rainer , Temps Friedrich
Published: April 2019

Femtosecond time-resolved absorption measurements of a magnetically bi-stable azopyridine Ni-porphyrin in solution at room temperature show that the photo-induced dynamics are dominated by transient low-spin ⇄ high-spin interconversion involving Ni (d2) and (d, d) states.
Ultrafast mapping of relaxation dynamics of ethylene cation
Authors: Lucchini Matteo , Murari Mario , Lucarelli Giacinto D. , Frassetto Fabio , Poletto Luca , Nisoli Mauro
Published: April 2019

The complex ultrafast molecular relaxation dynamics of ethylene, initiated by tunable vacuum-ultraviolet ~10-fs pulses, was measured. Exploiting state selectivity, an unprecedented time-energy mapping of the process was demonstrated on a few-femtosecond temporal scale.
Coupled nuclear-electronic dynamics in photoionization of H2
Authors: Cattaneo Laura , Vos Jannie , Bello Roger Yulio , Palacios Alicia , Heuser Sebastian , Pedrelli Luca , Lucchini Matteo , Cirelli Claudio , Martin Fernando , Keller Ursula
Published: April 2019

In this study we investigate the dissociative photoionization of molecular hydrogen H2, addressing the influence of autoionizing states and nuclear motion on the photoelectron dynamics. Experimental results are compared with ab initio calculations.
Switch of dimensionality of exciton diffusion in aggregates
Authors: Wolter Steffen , Würthner Frank , Kühn Oliver , Lochbrunner Stefan
Published: April 2019

The ultrafast exciton dynamics in J-aggregates of a perylene bisimide dye is investigated for temperatures down to 77 K revealing at low temperatures a decrease of the exciton mobility and a change in the dimensionality.
Encapsulation narrows excitonic homogeneous linewidth of exfoliated MoSe2 monolayer
Authors: Eric W. Martin , Horng Jason , Hanna G. Ruth , Paik Eunice , Wentzel Michael-Henr , Deng Hui , Steven T. Cundiff
Published: April 2019

We use collinear multidimensional coherent spectroscopy to measure van der Waals structures with a nearly diffraction-limited spot size. Encapsulation by boron nitride narrows the homogeneous and inhomogeneous linewidths of excitonic resonances in MoSe2.
Optically induced transient enhancement of a structural order parameter
Authors: Porer M. , Fechner M. , Bothschafter E. M. , Rettig L. , Narayan A. , Radovic M. , Savoini M. , Esposito V. , Rittmann J. , Kubli M. , Kubacka T. , Huber T. , Neugebauer M. , Abreu E. , Grübel S. , Beaud P. , Ingold G. , Lantz G. , Parchenko S. , Song S. , Sato T. , Aschauer U. , Spaldin N. , Johnson S. L. , Staub U.
Published: April 2019

We photoexcite SrTiO3 and EuTiO3 in their purely soft-mode-driven structurally distorted phase and trace the structural order parameter via ultra-short x-rays. We observe a rapid decay for SrTiO3 and an intriguing transient enhancement for EuTiO3.
Direct observation of structural dynamics upon photo-excitation in a spin crossover crystal with femtosecond electron diffraction
Authors: Jiang Yifeng , Liu Lai Chung , Müller-Werkmeister Henrike M. , Lu Cheng , Zhang Dongfang , Field Ryan L. , Sarracini Antoine , Moriena Gustavo , Collet Eric , Miller R. J. Dwayne
Published: April 2019

Photoinduced spin transitions are studied by femtosecond electron diffraction to understand ultrafast structural dynamics associated with intersystem crossing. The results indicate the structural reorganization occurs within 2.3 ps, as the metal-ligand bond distribution narrows during intramolecular vibrational energy redistribution.
Mapping spin-correlations with hard X-ray free-electron laser
Authors: Zhong Yinpeng , Epp Sascha , Krasniqi Faton , Foucar Lutz , Trigo Mariano , Jian Chen , Reis David , Wang Hailong , Zhao Jianhua , Lemke Henrik , Zhu Diling , Ullrich Joachim , Schlichting Iime
Published: April 2019

Time-resolved X-ray diffraction from Ga091Mn0 09As was recorded with a hard X-ray free-electron-laser. The influence of spin-orders on phonons was investigated; our result suggests a new method for mapping the spin-correlations in low doped magnetic systems, especially the short-range spin-correlation.
Optical-Field-Controlled Photoemission from Plasmonic Nanoparticles with a Sub-Two-Cycle, 6 nJ, Octave-spanning Ti:sapphire Oscillator
Authors: Chia Shih-Hsuan , Keathley Phillip D. , Putnam William , Scheiba Fabian , Hobbs Richard , Berggren Karl , Kartner Franz
Published: April 2019

We developed an optimized, carrier-envelope-phase-stable Ti:sapphire oscillator that generates 6 nJ pulses compressible to under sub- two- optical-cycles in duration. We used the optimized oscillator to demonstrate carrier-envelope-phase-sensitive (CEP-sensitive) photoemission from metallic nanoparticles in the near-infrared.
Ultrafast dynamics of hydrated excess protons in CH3CN:H2O mixtures
Authors: Dahms Fabian , Kundu Achintya , Pines Ehud , Fingerhut Benjamin P. , Nibbering Erik T. J. , Elsaesser Thomas
Published: April 2019

In a combined experimental and theoretical 2D-IR and pump-probe study we determine how ultrafast solvent motions govern the vibrational dynamics of the hydrated proton and the key role played by the underlying proton potential.
Towards understanding triiodide photochemistry in the solid state by femtosecond electron diffraction
Authors: Xian Rui , Hayes Stuart A. , Corthey Gaston , Morrison Carole A. , Marx Alexander , Valentyn I. Prokhorenko , Lu Cheng , Miller R. J. Dwayne
Published: April 2019

The photochemistry of the triiodide anion has been investigated by femtosecond electron diffraction. The time-resolved signal indicates the presence of reaction products and large-amplitude coherent motion produced by participating species. To reconstruct the atomic detail of the reaction and identify the major contributors to the detected signal, we outline the approach for atomic-level reconstruction.
Intersystem crossing dynamics in thionated uracils studied by time-resolved photoelectron spectroscopy: The effect of substituent position
Authors: Ullrich Susanne , Mohamadzade Abed
Published: April 2019

The photophysics of thionated uracils are investigated using time-resolved photoelectron spectroscopy with emphasis on evaluating differences in intersystem crossing dynamics with respect to substituent position.
Simulation of time-dependent ionization processes in acetylene
Authors: Schnappinger Thomas , Burger Christian , Atia-Tul-Noor Atia , Xu Han , Rosenberger Philipp , Harem Nida , Moshammer Robert , Sang Robert T. , Bergues Boris , Schuurman Michael S. , Litvinyuk Igor , Kling Matthias F. , de Vivie-Riedle Regina
Published: April 2019

We have investigated nuclear dynamics in bound and dissociating acetylene molecular ions in a time-resolved reaction microscopy experiment with a pair of few-cycle pulses. Different ionization processes were observed for acetylene. These time-dependent ionization processes are simulated using semi-classical on-the-fly dynamics revealing the underling mechanisms.
Time-resolved photoelectron spectroscopy of organic molecules in aqueous solutions
Authors: Hummert Johan , Reitsma Geert , Mayer Nicola , Ikonnikov Evgenii , Eckstein Martin , Kornilov Oleg
Published: April 2019

We use time-resolved photoelectron spectroscopy with wavelength-selected XUV femtosecond pulses to study photoinduced dynamics of organic molecules in solutions at millimolar concentrations. Upon electronic excitation we observe relaxation processes, such as excited state intramolecular proton transfer and trans-cis isomerization.
Femtosecond nonadiabatic dynamics in photosynthetic light harvesting
Authors: Foster Peter W. , Tiwari Vivek , Peters William K. , Jonas David M.
Published: April 2019

Fast and efficient energy transfer in photosynthetic antennas supports all life on earth. Nonadiabatic energy transfer drives unusual vibrations through tight coupling with electronic motion. Polarization dependent vibrational motion drives polarization independent femtosecond energy transfer.
On accuracy of numerical solution to boundary value problems on infinite domains with slow decay
Authors: Booker Kyle , Nec Yana
Published: April 2019

A numerical approach is developed to solve differential equations on an infinite domain, when the solution is known to possess a slowly decaying tail. An unorthodox boundary condition relying on the existence of an asymptotic relation for |y| ≫ 1 is implemented, followed by an optimisation procedure, allowing to obtain an accurate solution over a truncated finite domain. The method is applied to −(−Δ)γ/2u − u + up = 0 in ℝ, a non-linear integro-differential equation containing the fractional Laplacian, and is easily expanded to asymmetric boundary conditions or domains of a higher dimension.
Are we ready for circular economy? Towards zero waste in construction
Authors: Siew Renard
Published: April 2019

Over the past decade, the concept of circular economy (CE) has emerged encouraging a rethinking of the way products are designed so that they can be “made to be made again”, turning the conveyor belt of consumerism into a circle (a closed-loop supply chain) and hence eliminate waste. The construction sector, especially, is known to be one of the main contributors of material waste-to-landfill. This paper investigates (i) the causes of construction waste and (ii) the readiness of the construction sector in Malaysia to embrace CE. Based on the relative importance index (RII), the five main causes of construction waste in Malaysia identified include frequent design changes (RII = 0.853) by owner or agent during construction followed by poor site management and supervision (RII = 0.835), changes in material specification and type (RII = 0.803), rework (RII = 0.719) and lack of coordination between parties (RII = 0.680). Survey findings also show that a majority (75%) of stakeholders within the Malaysian construction industry is unfamiliar with the concept of CE while 90% of the respondents claim that they are not ready to implement such practices within the next 5 years. It is anticipated that the findings from this paper will be of interest to construction practitioners.
Design optimization of a three-stage transmission using advanced optimization techniques
Authors: Maputi Edmund S. , Arora Rajesh
Published: April 2019

Gear transmission systems are very important machine elements and their failure can lead to losses or damage of other mechanical components that comprise a machine or device. Since gears are applied in numerous mechanical devices, there is need to design and subsequently optimize them for intended use. In the present work, two objectives, viz., volume and center distance, are minimized for a rotary tiller to achieve a compact design. Two methods were applied: (1) analytical method, (2) a concatenation of the bounded objective function method and teaching–learning-based optimization techniques, thereby improving the result by 44% for the former and 55% for the latter. Using a geometric model and previous literature, the optimal results obtained were validated with 0.01 variation. The influence of design variables on the objective functions was also evaluated using variation studies reflecting on a ranking according to objective. Bending stress variation of 12.4% was less than contact stress at 51% for a defined stress range.
Short-term Resistance Training Increases APPL1 Content in the Liver and the Insulin Sensitivity of Mice Fed a Long-term High-fat Diet
Authors: Minuzzi Luciele Guerra , Kuga Gabriel Keine , Breda Leonardo , Gaspar Rafael Calais , Muñoz Vitor Rosetto , Pereira Rodrigo Martins , Botezelli José Diego , da Silva Adelino S. R. , Cintra Dennys Esper , de Moura Leandro Pereira , Ropelle Eduardo Rochete , Pauli José Rodrigo
Published: April 2019

Background APPL1, an adapter protein, interact directly with adiponectin receptors mediating adiponectin signaling and acting as a critical regulator of the crosstalk between adiponectin and insulin signaling pathway. The inadequate level of physical activity, high-calorie intake, or both lead to adverse consequences on health, like insulin resistance. On the order hand, physical exercise acts positively in the insulin action.

Purpose Here, we investigated the effects of short-term resistance training (RT) on APPL1 content and adiponectin pathway in the liver of mice fed a long-term high-fat diet.

Methods Swiss mice were distributed into 3 groups: Mice that fed a chow diet (CTR); Mice fed a high-fat diet for 16 months (HFD); and mice fed a high-fat diet for 16 months and submitted to a climbing ladder exercise (RT) for 7 days (HFD-EXE).

Results The results show that short-term RT increases the APPL1 content but wasn’t able to alter AdipoR1 and AdipoR2 content in the liver of HFD-EXE mice. However, this increase in the APPL1 content in response to RT was accompanied by improvement in the insulin sensitivity.

Conclusion In summary, our data suggested that short-term RT improves glycemic homeostasis and increases APPL1 in the hepatic tissue of mice treated with long-term high-fat diet.