bluuebunny/crossref_metadata_2025 huggingface dataset:
6Li210B4O7 NPs-loaded plastic scintillators for fast/thermal neutron and gamma ray detection
Authors: Frangville Camille , Grabowski Amélie , Dumazert Jonathan , Montbarbon Eva , Lynde Clément , Coulon Romain , Venerosy Amélie , Bertrand Guillaume H. V. , Hamel Matthieu
Published: May 2019

We report herein the synthesis of a new series of plastic scintillators (PSs) loaded with 6Li210B4O7 nanoparticles (NPs), as new radioluminescent sensors for fast/thermal neutron and gamma ray detection in the critical context of homeland security.
A synthetic chemist's guide to electroanalytical tools for studying reaction mechanisms
Authors: Sandford Christopher , Edwards Martin A. , Klunder Kevin J. , Hickey David P. , Li Min , Barman Koushik , Sigman Matthew S. , White Henry S. , Minteer Shelley D.
Published: May 2019

A range of electroanalytical tools can be applied to studying redox reactions, probing key mechanistic questions in synthetic chemistry.
Stable and tunable plasmon resonance of molybdenum oxide nanosheets from the ultraviolet to the near-infrared region for ultrasensitive surface-enhanced Raman analysis
Authors: Wang Jinhu , Yang Yinhua , Li Hua , Gao Jun , He Ping , Bian Liang , Dong Faqin , He Yi
Published: May 2019

Preparation of color-tunable and stable plasmonic MoO3 nanomaterials remains challenging, due to the lack of an effective preparation strategy and surface protection in heavily doped MoO3.
Electrospun Li3V2(PO4)3 nanocubes/carbon nanofibers as free-standing cathodes for high-performance lithium-ion batteries
Authors: Peng Yi , Tan Rou , Ma Jianmin , Li Qiuhong , Wang Taihong , Duan Xiaochuan
Published: May 2019

A novel free-standing architecture with Li3V2(PO4)3 nanocubes embedded in N-doped carbon nanofibers has been successfully prepared through a facile ionic liquid-assisted electrospinning method, which exhibits an outstanding electrochemical performance including high specific capacity, stable cycling performance and superior rate capability.
Boosting the hydrogen evolution performance of a ternary MoxCo1−xP nanowire array by tuning the Mo/Co ratio
Authors: Zhang Yintong , Wang Zhiyuan , Du Feng , He Huichao , Alsaedi Ahmed , Hayat Tasawar , Li Tao , Li Guo-Ling , Zhou Yong , Zou Zhigang
Published: May 2019

Volcano-like electrocatalytic HER activity of MoxCo1−xP/CC due to the good balance of the double-sided effect.
Recent progress in the hybrids of transition metals/carbon for electrochemical water splitting
Authors: Hu Qi , Li Guomin , Han Zhen , Wang Ziyu , Huang Xiaowan , Yang Hengpan , Zhang Qianling , Liu Jianhong , He Chuanxin
Published: May 2019

This review summarizes the recent progress made in the synthesis of transition metal/carbon hybrids (i.e. metal alloys/carbon, metal sulfides/carbon, and metal phosphides/carbon) for electrochemical water splitting.
Fabrication of magnesium oxide nanoparticles by solvent alteration and their bactericidal applications
Authors: Bhattacharya Proma , Swain Sarpras , Giri Lopamudra , Neogi Sudarsan
Published: May 2019

MgO nanoparticles are synthesized using water, ethanol and aqueous CTAB solution. The nanoparticles synthesized in ethanol exhibited smallest size, maximum reactive oxygen species generation and maximum antibacterial ability, and low haemolysis.
Superposition of interface and volume type resistive switching in perovskite nanoionic devices
Authors: Bagdzevicius Sarunas , Boudard Michel , Caicedo José Manuel , Rapenne Laetitia , Mescot Xavier , Rodríguez-Lamas Raquel , Robaut Florence , Santiso Jose , Burriel Mónica
Published: May 2019

Non-filamentary and non-volatile reproducible resistive switching with a high memory window has been obtained for novel nanoionic memristors based on GdBaCo2O5+δ.
MicroRNA-140-5p inhibits cell proliferation, migration and promotes cell apoptosis in gastric cancer through the negative regulation of THY1-mediated Notch signaling
Authors: Wu Kun , Zou Jun , Lin Chao , Jie Zhi-Gang
Published: May 2019

Studies have highlighted the importance of microRNAs (miRs) in the development of various cancers, including gastric cancer (GC), a commonly occurring malignancy, accompanied by high recurrence and metastasis rate. The aim of the current study was to investigate the role of miR-140-5p in GC. Microarray expression profiles were initially employed to screen the differentially expressed gene related to GC, and the miR regulating the gene was predicted accordingly. The data obtained indicated that thymus cell antigen 1 (THY1) was differentially expressed in GC and confirmed to be a target gene of miR-140-5p. Poorly expressed miR-140-5p and highly expressed THY1 were observed in the GC tissues. SGC-7901 cells were treated with miR-140-5p mimic/inhibitor, siRNA against THY1 and siRNA against Notch1 in order to determine their regulatory roles in GC cell activities. The relationship of miR-140-5p, THY1 and the Notch signaling pathway was subsequently identified. Moreover, cell proliferation, migration, invasion and apoptosis were determined using 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), wound-healing, transwell assay and flow cytometry, respectively. The overexpression of miR-140-5p and silencing of THY1 resulted in a diminished expression of the Notch signaling pathway-related proteins, as well as inhibited proliferation, migration and invasion of GC cells, enhanced expression of pro-apoptotic proteins in addition to elevated apoptosis rate. Taken together, the present study suggests that miR-140-5p directly targets and negatively regulates THY1 expression and inhibits activation of the Notch signaling pathway, whereby the up-regulation of miR-140-5p inhibits development of GC, highlighting the promise of miR-140-5p as a potential target for GC treatment.
CRISPR/Cas9 applications in gene therapy for primary immunodeficiency diseases
Authors: De Ravin Suk See , Brault Julie
Published: May 2019

Primary immunodeficiency diseases (PIDs) encompass a range of diseases due to mutations in genes that are critical for immunity. Haploinsufficiency and gain-of-function mutations are more complex than simple loss-of-function mutations; in addition to increased susceptibility to infections, immune dysregulations like autoimmunity and hyperinflammation are common presentations. Hematopoietic stem cell (HSC) gene therapy, using integrating vectors, provides potential cure of disease, but genome-wide transgene insertions and the lack of physiological endogenous gene regulation may yet present problems, and not applicable in PIDs where immune regulation is paramount. Targeted genome editing addresses these concerns; we discuss some approaches of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas system applicable for gene therapy in PIDs. Preclinical repair of gene mutations and insertion of complementary DNA restore endogenous gene regulation and they have shown very promising data for clinical application. However, ongoing studies to characterize off-target genotoxicity, careful donor designs to ensure physiological expression, and maneuvers to optimize engraftment potential are critical to ensure successful application of this next-gen targeted HSC gene therapy.
Modelling and kink correction of bulk CMOS at liquid helium temperature
Authors: Li Zhen , Luo Chao , Lu Tengteng , Xu Jun , Kong Weicheng , Guo Guoping
Published: May 2019

Cryogenic characterisation and modelling of CMOS technology (1.8 and 5 V) is presented in this Letter. Several P‐type MOS and N‐type MOS transistors with different width to length ratios were extensively characterised under various bias conditions at temperatures ranging from 300 K down to 4.2 K. The authors extracted their fundamental physical parameters and developed a compact model based on BSIM3V3. A simple subcircuit was built to correct the kink effect. The RMS error of test results and modelling results is 3%.
Identification of low‐frequency oscillation mode and improved damping design for virtual synchronous machines in microgrid
Authors: Sun Chu , Joos Geza , Bouffard Francois
Published: May 2019

The low‐frequency dynamics of virtual synchronous machine (VSM) depends on multiple factors. In this study, the oscillation mode of a single VSM is first identified by exploring the evolution of oscillation from synchronous mode to sub‐synchronous mode with the variation of structure and parameters. The inter‐oscillation modes among multiple VSMs modelled in quasi‐state phasor domain are then studied by decomposing into mean motion and relative motion. Inspired by and weak‐coupling‐based coherency identification, the associated VSM group can be fast identified and used for effective stabilizer location. The approximate eigenvalues can be fast obtained by system decomposition in uniform‐damping scenarios or by extended‐equal‐area‐criterion approach in non‐uniform‐damping scenario. An improved design for lead–lag compensation is proposed to damp both synchronous and sub‐synchronous oscillation of VSMs. Effectiveness of the proposed control strategy in grid‐connected/islanded mode is verified with real‐time simulation.
Experimental study on low‐THz automotive radar signal attenuation during snowfall
Authors: Norouzian Fatemeh , Marchetti Emidio , Hoare Edward , Gashinova Marina , Constantinou Costas , Gardner Peter , Cherniakov Mikhail
Published: May 2019

Experimental measurement results of automotive radar signal attenuation during various intensities of snowfall at the current automotive radar frequency (77 GHz) and low‐terahertz (THz) (100–300 GHz) frequencies are presented and compared in this study. The attenuation is characterised by measuring the ratio of the received power from a reference target through snow precipitation of various intensities and through the same path with no precipitation. Statistical analysis of the attenuation is presented. Higher attenuation is measured at a higher frequency, and also attenuation increases as snowfall rate and liquid water content in snowflakes increases. This study is fundamentally important to investigate the effect of adverse weather conditions on low‐THz radar performance in comparison with the current automotive radars operating in the traditional mm‐wave band. In addition, the effects of low‐THz wave attenuation and scattering due to typical contaminants formed on the radome of automotive radars and reflection from common objects on the road are presented.
Microwave‐based sensor for power transformers’ insulation oil monitoring
Authors: Benaissa Mohamed Amine , Mokraoui Amine , Moulai Hocine , Idir Omar
Published: May 2019

Here, a new device is presented to supervise the ageing process of insulating oils used in power transformers. It is based on the use of a microstrip antenna whose electrical properties are very sensitive to the permittivity and conductivity of the medium. As many works showed that the drift of permittivity due to transformers aging is very small, the achieved sensor must exhibit a great sensitivity. In order to assess the aging of the insulation oil, the authors will track the resonant frequency of the antenna which is directly related to the permittivity of the oil, and the reflection coefficient level of the antenna at the resonance frequency which is linked to the conductivity. The experiments have been made on vegetable oil and results revealed to be enthusiastic. The sensor is proposed to be used in an embedded system in order to achieve a low cost and safe preventive diagnosis.
Biodistribution of nanodiamonds in the body of mice using EPR spectrometry
Authors: Inzhevatkin Evgeny , Baron Alexey , Maksimov Nikolai , Volkova Marina , Puzyr Alexey , Ronzhin Nikita , Bondar Vladimir
Published: May 2019

In vitro experiments proved the usefulness of electron paramagnetic resonance (EPR) spectrometry for detecting detonation nanodiamonds (NDs) in samples of biomaterials (blood and homogenates of organs of mice). A characteristic EPR signal (g = 2.003, ΔH ≃ 10 G) was detected in biomaterials containing NDs, and its intensity linearly increased at nanoparticle concentrations of between 1.6 and 200 µg/ml. In vivo experiments demonstrated that EPR spectrometry was effective for monitoring the inter‐organ distribution of NDs intravenously injected to mice. In 2.5 h after the injection of NDs, the nanoparticles mainly accumulated in the lungs and liver of the animals – about 25 and 20%, respectively, of the initially injected NDs. The amounts of NDs accumulated in the heart and kidneys were considerably lower. Also, EPR spectrometry did not detect NDs in the blood, spleen, brain, and femoral muscles of mice. Ten days after injection, EPR spectrometry detected redistribution of NDs in mice. The amounts of nanoparticles decreased approximately by a factor of 3.5 in the lungs and increased almost by a factor of 3 in the liver; NDs were detected in the spleen. This study suggests ways to use EPR spectrometry to study the distribution, accumulation, and elimination of detonation NDs injected into laboratory animals.
Revisiting the dust properties in the molecular clouds of the Large Magellanic Cloud
Authors: Paradis D. , Mény C. , Juvela M. , Noriega-Crespo A. , Ristorcelli I.
Published: May 2019

Context. Some Galactic molecular clouds show signs of dust evolution as compared to the diffuse interstellar medium, most of the time through indirect evidence such as color ratios, increased dust emissivity, or scattering (coreshine). These signs are not a feature of all Galactic clouds. Moreover, molecular clouds in the Large Magellanic Cloud (LMC) have been analyzed in a previous study based on Spitzer and IRIS data, at 4′ angular resolution, with the use of one single dust model, and did not show any signs of dust evolution.

Aims. In this present analysis we investigate the dust properties associated with the different gas phases (including the ionized phase this time) of the LMC molecular clouds at 1′ angular resolution (four times greater than the previous analysis) and with a larger spectral coverage range thanks to Herschel data. We also ensure the robustness of our results in the framework of various dust models.

Methods. We performed a decomposition of the dust emission in the infrared (from 3.6 to 500 μm) associated with the atomic, molecular, and ionized gas phases in the molecular clouds of the LMC. The resulting spectral energy distributions were fitted with four distinct dust models. We then analyzed the model parameters such as the intensity of the radiation field and the relative dust abundances, as well as the slope of the emission spectra at long wavelengths.

Results. This work allows dust models to be compared with infrared data in various environments for the first time, which reveals important differences between the models at short wavelengths in terms of data fitting (mainly in the polycyclic aromatic hydrocarbon bands). In addition, this analysis points out distinct results according to the gas phases, such as dust composition directly affecting the dust temperature and the dust emissivity in the submillimeter and different dust emission in the near-infrared (NIR).

Conclusions. We observe direct evidence of dust property evolution from the diffuse to the dense medium in a large sample of molecular clouds in the LMC. In addition, the differences in the dust component abundances between the gas phases could indicate different origins of grain formation. We also point out the presence of a NIR-continuum in all gas phases, with an enhancement in the ionized gas. We favor the hypothesis of an additional dust component as the carrier of this continuum.
Plasma injection into a solar coronal loop
Authors: Li L. P. , Peter H.
Published: May 2019

Context. The details of the spectral profiles of extreme UV emission lines from solar active regions contain key information for investigating the structure, dynamics, and energetics of the solar upper atmosphere.

Aims. We characterize the line profiles not only through the Doppler shift and intensity of the bulk part of the profile. More importantly, we investigate the excess emission and asymmetries in the line wings to study twisting motions and helicity.

Methods. We used a raster scan of the Interface Region Imaging Spectrograph (IRIS) in an active region. We concentrated on the Si IV line at 1394 Å, which forms just below 0.1 MK, and followed the plasma that moves in a cool loop from one footpoint to the other. We applied single-Gaussian fits to the line core, determined the excess emission in the red and blue wings, and derived the asymmetry of the red and blue wings.

Results. The blue wing excess at one footpoint shows injection of plasma into the loop that then flows to the other side. At the same footpoint, redshifts in the line core indicate that energy is deposited at around 0.1 MK. The enhanced pressure would then push the cool plasma down and inject some plasma into the loop. In the middle part of the loop, the spectral tilts of the line profiles indicate that the magnetic field has a helical structure, and the line wings are symmetrically enhanced. This is an indication that the loop is driven through the injection of helicity at the loop feet.

Conclusions. If the loop is driven to be helical, then the magnetic field can be expected to be in a turbulent state, as has been shown by existing magnetohydrodynamics models. The turbulent motions might explain the (symmetric) line wing enhancements that have also been seen in loops at coronal temperatures, but are not understood so far.
Palladium(II) Acetate Mediated Dimerization/Cycloisomerization of 2-Sulfonyl-4-alkynones: Synthesis of trans-1,2-Difurylethylenes
Authors: Chang Meng-Yang , Lai Kai-Xiang
Published: May 2019

This paper describes a one-pot, atom-economic, easy-operation, open-atmosphere method for the synthesis of trans-1,2-difuryl­ethylenes by the straightforward Pd(OAc)2-mediated dimerization/cycloisomerization of 2-sulfonyl-4-alkynones in the presence of Na2CO3 and PPh3 under refluxing EtOH conditions, and proposes and discusses a plausible mechanism. This protocol provides a highly effective annulation via two carbon–oxygen (C–O) single-bond and one carbon–carbon (C=C) double-bond formations.
Total Knee Arthroplasty Outcomes in Patients with Medicare, Medicare Advantage, and Commercial Insurance
Authors: Starring Hunter , Waddell William H. , Steward William , Schexnayder Stuart , McKay Jack , Leonardi Claudia , Bronstone Amy , Dasa Vinod
Published: May 2019

As more commercial insurance companies adopt a bundled reimbursement model, similar to the Comprehensive Care for Joint Replacement (CJR) algorithm for Medicare beneficiaries, accurate risk adjustment of patient-reported outcomes (PROs) is critical to ensure success. With this movement toward bundled reimbursement, it is unknown if a formula adjusting for similar risks in the Medicare population could be applied to PROs in commercially insured and Medicare Advantage populations undergoing total knee arthroplasty (TKA). This study was performed to compare PROs after TKA in these insurance groups after adjusting for proposed risks. Demographics and clinical data were abstracted from medical records of 302 patients who underwent TKA performed by a single surgeon at a university-based orthopaedic practice during 2013 to 2017. Differences in PROs between commercially insured, Medicare Advantage, and Medicare patients during the 6 months following surgery were evaluated while controlling for demographics, clinical data, and baseline PRO scores. Medicare and Medicare Advantage patients were older (p < 0.001) and had more comorbidities (p = 0.001) than commercial patients. During the first 3 months following TKA, patients in all three groups experienced similar rates of recovery. At 6 months after surgery, outcomes began to diverge by insurance group. Medicare patients reported significantly less ability to perform activities of daily living (78.6 vs. 63.2; p = 0.001), worse physical function (39.6 vs. 44.9; p = 0.003), and more pain interference (57.9 vs. 52.4; p = 0.018) at day 180 than commercially insured patients. There were no statistically significant differences between Medicare Advantage patients and either commercially insured or Medicare patients. Therefore, commercial insurance companies that intend to apply a risk-adjusted equation similar to the CJR algorithm to commercial populations should be cautioned since the postoperative outcomes in this investigation differed after adjusting for the same risk factors that have been proposed for inclusion in the CJR algorithm. Nonetheless, further studies should be performed to ensure that companies participating in bundled reimbursement models have a positive influence on comprehensive health care for patients and providers. This is a level III, retrospective prognostic study
Medial Patellofemoral Ligament Reconstruction in Traumatic Patellar Dislocation without Patellar Fixation
Authors: Ibrahim Samir Abdulrazik , Shohdy Emad Mureed , Ramadan Sami Abdulghaffar , Almisfer Abdulrahman Khalid , Abdulsattar Wael Shoabe , Khairat Sherif
Published: May 2019

Acute traumatic patellar dislocation is a common injury, and spontaneous reduction may occur at the time of injury or may be reduced at the field of the accident by someone. It may be associated with osteochondral fractures and rupture of medial patellar stabilizers leading to recurrent patellar instability. The aim of this prospective study was to evaluate the outcomes of medial patellofemoral (PF) ligament (MPFL) reconstruction in recurrent traumatic patellar dislocation. Forty-five patients presented with PF instability as a result of traumatic rupture MPFL with normal patellar tracking underwent MPFL reconstruction without patellar fixation hardware through two parallel transpatellar tunnels and one screw in femoral tunnel. All patients were evaluated clinically preoperatively and at a minimum follow-up of 24 months, and International Knee Documentation Committee (IKDC) and Kujala scores were used to assess the clinical results. All patients were available for evaluation at a minimum of 24 months (up to 36 months). The mean age of these patients at the time of surgery was 22.82 years (range: 18–34 years). All patients gave history of trauma of their knees. Mean IKDC scale showed significant improvement as it rose from 47.17 preoperatively to 77.94 postoperatively, and mean Kujala score rose from 53.88 preoperatively to 86.24 postoperatively (p < 0.001). No recurrence of dislocation was recorded. Only three patients had mild atrophy of thigh and one patient had some difficulty in jumping. Reconstruction of MPFL by this method provides good clinical result in the treatment of PF instability by using autologous graft (semitendinosus and gracilis). Less hardware were used with less complications.
Development and Validation of Early Warning Criteria to Identify Escalated Care Events in Neonatal Intensive Care Unit Patients
Authors: Shivananda Sandesh , Twiss Jennifer , Paterson Debie , Dyck Gillian , Becker Stephanie , Razack Abdul , Gupta Shikha , Dutta Sourabh , Suresh Gautham
Published: May 2019

Objective This study aimed to identify and validate the diagnostic utility of a set of clinical and laboratory criteria (early warning criteria [EWC]) that portend a clinical deterioration event (escalated care event [ECE]) in neonatal intensive care unit (NICU) patients.

Study Design Using the RAND appropriateness method, we first established a consensus on seven ECE, that is, events that require additional monitoring, treatment, or stay in the NICU or that were associated with morbidity. We then established consensus on EWC that could portend an ECE from an initial set of 32 potential EWC items to a final set of 10 items. The occurrence and nonoccurrence of EWC and ECE were prospectively identified and tracked over 9 weeks.

Results Among 170 NICU patients studied (2,502 patient-days), the frequency of an EWC was 53 per 1,000 patient-days. Of these patients, 41% had an EWC and 16% had an ECE. An EWC was followed by an ECE within 72 hours, 37% of the time, and within a median time interval of 113 minutes. The sensitivity, specificity, positive predictive values, and negative predictive values of EWC in identifying an ECE were 0.96, 0.69, 0.37, and 0.99, respectively.

Conclusion A simple bedside NICU-specific EWC identifies neonates likely to develop ECEs in the NICU.
Acidemia Can Occur Despite Category I Tracing
Authors: Bruno Ann M. , López Julia D. , Stout Molly J. , Tuuli Methodius G. , Macones George A. , Cahill Alison G.
Published: May 2019

Objective Electronic fetal monitoring (EFM) is intended to assess fetal well-being during labor. Our objective was to test the hypothesis that findings of a category I tracing at any time in the 60 minutes prior to delivery would rule out neonatal acidemia.

Study Design This was a planned secondary analysis of a single-center prospective cohort study of 8,580 singleton pregnancies undergoing labor with nonanomalous infants at term. Monitoring was reviewed by obstetric research nurses at 10-minute intervals in the 60 minutes prior to delivery. The primary outcome was acidemia, defined as an umbilical cord arterial pH of 7.10 or less.

Results Of the 4,274 patients included, 42 (0.98%) infants had acidemia at birth. Of the 42 infants with acidemia, 13 (31%) had category I tracings in the 30 minutes prior to delivery. Three (7%) infants had neonatal acidemia despite category I tracing for >40 minutes in the 60 minutes prior to delivery.

Conclusion Even in the presence of category I tracing in the 60 minutes prior to delivery, neonatal acidemia can still occur. Periods of category I should be interpreted within the clinical context of a priori risk for acidemia, knowing that it does not completely rule out acidemia.
The interfacial structure of nano- and micron-sized oil and water droplets stabilized with SDS and Span80
Authors: Zdrali Evangelia , Etienne Gianluca , Smolentsev Nikolay , Amstad Esther , Roke Sylvie
Published: May 2019

In this work, we provide a comparison between the stability and the interfacial structure of micrometer-sized and nanometer-sized droplets by employing a multi-instrumental approach comprised of the surface-sensitive technique of sum frequency scattering as well as dynamic light scattering and microscopy. We monitor the stability of oil-in-water and water-in-oil emulsions and the structure of surfactants at the oil/water nano-interface, when stabilized with an oil-soluble neutral surfactant (Span80), a water-soluble anionic surfactant (sodium dodecyl sulfate, SDS), or with a combination of the two. Micron-sized droplets are found to be stabilized only when a surfactant soluble in the continuous phase is present in the system, in agreement with what is traditionally observed empirically. Surprisingly, the nanodroplets behave differently. Both oil and water nanodroplets can be stabilized by the same (neutral Span80) surfactant but with different surface structures. A combination of SDS and Span80 also suffices, but for the case of water droplets, the strongly amphiphilic SDS molecules are not detected at the interface. For the case of oil droplets, both surfactants are at the interface but do not structurally affect one another. Thus, it appears that, in this study, empirical rules such as the Bancroft rule, the hydrophile–lipophile–balance scale, and the surfactant affinity difference predict the stability of the micrometer-sized droplets better than the nanometer-sized ones, probably due to a different balance of interactions on different length scales.
High power folded waveguide traveling wave tube based on variable-width technology
Authors: Lu Zhigang , Ge Weihua , Wen Ruidong , Su Zhicheng , Wang Zhanliang , Tang Tao , Gong Huarong , Gong Yubin
Published: May 2019

Variable-width technology applied to the folded waveguide traveling wave tube (FW-TWT) is proposed in this paper to suppress the lower band-edge oscillation and to expand the operating bandwidth when the operating frequency shifts toward the lower band for obtaining larger output power. Changes in the width of the slow wave structure (SWS) determine the variation of the lower-cutoff-frequency (LCF), which makes the LCF's distribution a frequency range rather than a specific frequency-point. The lower band-edge oscillation will not be focused on a special position but distributed in a frequency-band range in which multiple oscillation modes compete with each other near the LCF. The lower band-edge oscillation can be suppressed by mode competition to some extent. In addition, the width variation of SWS also results in the phase-velocity variation, and thus, the operating bandwidth of FW-TWT can be further improved by the optimized design of variable-width-SWS parameters. Beam-wave interaction simulations predicted that power and bandwidth improvements have been achieved without the lower band-edge oscillation. Meanwhile, four solutions are given for further certifying the effectiveness of the variable-width method in lower band-edge oscillation suppression and bandwidth widening. An output power level of over 350 W in a frequency range of 85–90 GHz (5 GHz) is obtained, with a maximum power of ∼648 W and an electron efficiency of ∼12.1% at 88 GHz with a beam current of 260 mA and a beam voltage of 20.5 kV.
Effects of the pulse width and oxygen admixture on the production of reactive species in gas- and liquid-phases exposed by bipolar microsecond-pulsed atmospheric pressure helium plasma jets
Authors: Joh Hea Min , Baek Eun Jeong , Kim Sun Ja , Chung T. H.
Published: May 2019

Atmospheric pressure helium plasma jets driven by a low-frequency bipolar microsecond-pulsed voltage were characterized. Some characteristic features of plasma jets were discussed with an emphasis on the temporal evolution of discharge current and light emission. The electrical and optical characteristics of the jet exhibited quite a strong dependence on the pulse width and oxygen gas admixture. We investigated the effects of the pulse width and oxygen admixture on the production of reactive species in gas and liquid phases. The concentrations of reactive species were measured at the plasma-liquid surface and inside the plasma-treated liquids using ultraviolet absorption spectroscopy, the chemical probe method, and UV-VIS spectrophotometry. In the range of pulse widths of 1.5–5.5 μs, the 3.5 μs case was observed to exhibit higher values in discharge current and optical emission intensity. The OH densities estimated at the plasma-liquid interface and inside the plasma-treated liquid were observed to vary with the pulse width, and it exhibited a similar trend of change to those of discharge current, optical emission intensity, and the concentrations of the long-living reactive species, H2O2 and NO3−, in the plasma-treated liquids. Around the oxygen admixture of 10 SCCM (=1% vol. %), the discharge current and wavelength-integrated optical intensity were maximal, but the estimated OH density inside the plasma-treated liquid exhibits a slight rise with the increasing oxygen admixture, reaching the highest at 20 SCCM, and then decreases slightly.
Probing ultrafast shock-induced chemistry in liquids using broad-band mid-infrared absorption spectroscopy
Authors: Bowlan Pamela , Powell Michael , Perriot Romain , Martinez Enrique , Kober Edward M. , Cawkwell M. J. , McGrane Shawn
Published: May 2019

We probe shock-induced chemistry in two organic liquids by measuring broadband, midinfrared absorption in the 800–1400 cm−1 frequency range. To test this new method and understand the signatures of chemical reactions in time resolved vibrational spectra, we compared liquid benzene shocked to unreactive conditions (shocked to a pressure of 18 GPa for a duration of 300 ps) to nitromethane under reactive conditions (25 GPa). We see clear signatures of shock-induced chemistry that are distinguishable from the pressure- and temperature-induced changes in vibrational mode shapes. While shocked benzene shows primarily a broadening and shifting of the vibrational modes, the nitromethane vibrational modes vanish once the shock wave enters the liquid and simultaneously, a spectrally broad feature appears that we interpret as the infrared spectrum of the complex mixture of product and intermediate species. To further interpret these measurements, we compare them to reactive quantum molecular dynamics simulations, which gives qualitatively consistent results. This work demonstrates a promising method for time resolving shock-induced chemistry, illustrating that chemical reactions produce distinct changes in the vibrational spectra.
Phase field modeling of domain dynamics and polarization accumulation in ferroelectric HZO
Authors: Saha Atanu K. , Ni Kai , Dutta Sourav , Datta Suman , Gupta Sumeet
Published: May 2019

In this work, we investigate the accumulative polarization (P) switching characteristics in ferroelectric (FE) thin films under the influence of sequential sub-coercive electric-field pulses. Performing the dynamic phase-field simulation (based on time-dependent Landau-Ginzburg model) and experimental measurement on Hf0.4Zr0.6O2 (HZO), we analyze the electric field induced domain-wall (DW) motion and the resultant P accumulation process in FE. According to our analysis, even in the absence of an applied electric field, the DW can potentially undergo spontaneous motion. Such a DW instability leads to spontaneous P-excitation and relaxation processes, which play a pivotal role in accumulative P-switching in an FE grain. We show that the extent of such P accumulation increases with the increase in the applied electric field, increase in excitation time and decrease in relaxation time. Finally, by considering an ensemble of grains with local and global coercive field distributions, we model the P-accumulation process in a large area HZO sample. In such a multi-grain scenario, the dependency of P accumulation on the applied electric field pulse attributes follows similar features as that of a single-grain, although the spontaneous processes (excitation/relaxation) are less prominent in large area sample.
Study of delocalized and localized states in ZnSeO layers with photoluminescence, micro-photoluminescence, and time-resolved photoluminescence
Authors: Wełna M. , Baranowski M. , Kudrawiec R.
Published: May 2019

In this work, we present a detailed investigation of the low temperature emission properties of ZnSeO alloys by means of photoluminescence, micro-photoluminescence, and time-resolved photoluminescence. We show that the low temperature broad photoluminescence spectrum of ZnSeO attributed to the recombination of localized excitons is composed of sharp lines related to individual trapping states. Based on studies of photoluminescence thermal quenching from individual trapping states and photoluminescence dynamics, the mechanism of nonradiative recombination in ZnSeO alloys is discussed. Moreover, an unexpected decrease of the low temperature Stokes shift with increasing oxygen content is observed in contrast to what has been reported for GaAs based highly mismatched alloys. The possible origin of this effect is proposed.
Tunable perfect negative reflection based on an acoustic coding metasurface
Authors: Zuo Shuyu , Cheng Ying , Liu Xiaojun
Published: May 2019

Artificial manipulation of acoustic waves is a highly active research area, in which negative reflection is an exotic phenomenon. Emerging acoustic coding metasurfaces (ACMs) show great power in controlling acoustic waves. Here, we propose an ACM, where the state “0” or “1” is achieved by pushing up or pressing down a rigid rectangular strip. The ACM with a tunable coding sequence can adjust the direction of negative reflection as well as suppress the specular reflection. The feasibility of the ACM is demonstrated by totally reflecting the incident acoustic waves from 22° to the directions of −39°, −47°, and −61°. Furthermore, the ACM can spread the incident white noise into its acoustic spectral components like rainbows. This work may open diverse routes toward reconfigurable acoustic metasurfaces that are critical for practical functional devices, which are promising in potential applications including acoustic beam steering, retro-reflection, and surface wave sensing.
Phase detection of coherence singularities and determination of the topological charge of a partially coherent vortex beam
Authors: Lu Xingyuan , Zhao Chengliang , Shao Yifeng , Zeng Jun , Konijnenberg Sander , Zhu Xinlei , Popov Sergei , Urbach H. Paul , Cai Yangjian
Published: May 2019

In the theory of partial coherence, coherence singularities can occur in the spectral degree of coherence (SDOC): in case the fields at two different points are completely uncorrelated, the phase of the SDOC is undefined. For a partially coherent vortex beam, the detection of coherence singularities is linked to the measurement of topological charge, whose magnitude equals the number of ring dislocations in its far field amplitude. However, the phase distribution of coherence singularities is rarely mentioned in the literature and the amplitude distribution can hardly reflect the sign of topological charge. In this letter, we present a phase-analysis method for measuring the coherence singularities by introducing a movable perturbation at a certain point in an illumination window of a finite size. Using the proposed method, we measure experimentally the coherence singularities of a partially coherent vortex beam in the focal plane. From the results, the magnitude and sign of the topological charge can be determined simultaneously from the phase distribution of the coherence singularities. Our results can find application in information transmission.
Protecting superconducting qubits from phonon mediated decay
Authors: Rosen Yaniv J. , Horsley Matthew A. , Harrison Sara E. , Holland Eric T. , Chang Allan S. , Bond Tiziana , DuBois Jonathan L
Published: May 2019

For quantum computing to become fault tolerant, the underlying quantum bits must be effectively isolated from the noisy environment. It is well known that including an electromagnetic bandgap around the qubit operating frequency improves coherence for superconducting circuits. However, investigations of bandgaps to other environmental coupling mechanisms remain largely unexplored. Here, we present a method to enhance the coherence of superconducting circuits by introducing a phononic bandgap around the device operating frequency. The phononic bandgaps block resonant decay of defect states within the gapped frequency range, removing the electromagnetic coupling to phonons at the gap frequencies. We construct a multiscale model that derives the decrease in the density of states due to the bandgap and the resulting increase in defect state T1 times. We demonstrate that emission rates from in-plane defect states can be suppressed by up to two orders of magnitude. We combine these simulations with theory for resonators operating in the continuous-wave regime and show that improvements in quality factors are expected by up to the enhancement in defect T1 times. Furthermore, we use full master equation simulation to demonstrate the suppression of qubit energy relaxation even when interacting with 200 defect states. We conclude with an exploration of device implementation including tradeoffs between fabrication complexity and qubit performance.
Extremely high-aspect-ratio ultrafast Bessel beam generation and stealth dicing of multi-millimeter thick glass
Authors: Meyer R. , Froehly L. , Giust R. , Del Hoyo J. , Furfaro L. , Billet C. , Courvoisier F.
Published: May 2019

We report on the development of an ultrafast beam shaper capable of generating Bessel beams of high cone angle that maintain a high intensity hot spot with subwavelength diameter over a propagation distance in excess of 8 mm. This generates a high intensity focal region with extremely high aspect ratio exceeding 10 000:1. The absence of intermediate focusing in the shaper allows for shaping very high energies, up to Joule levels. We demonstrate a proof of principle application of the Bessel beam shaper for stealth dicing of thick glass, up to 1 cm. We expect that this high energy Bessel beam shaper will have applications in several areas of high intensity laser physics.
Planar multiresonance reactive shield for reducing electromagnetic interference in portable wireless power charging application
Authors: Park Jaehyoung , Park Chanjun , Shin Yujun , Kim Dongwook , Park Bumjin , Cho Jaeyong , Choi Junsung , Ahn Seungyoung
Published: May 2019

Wireless power transfer (WPT) technologies are currently growing in popularity because of problems with batteries in portable devices, such as the added weight and the inconvenience of conventional wired charging methods. However, wireless charging systems generate leakage magnetic fields, causing malfunctions in adjacent electronic devices. Technologies to suppress electromagnetic interference (EMI) from portable WPT systems are required to prevent this problem. In this paper, we propose a topology design for a multiresonance reactive shield to suppress the EMI from WPT systems. The proposed shield employs closed loops, which are located peripheral to the WPT coil and resonance matching capacitor. The power efficiency and shielding performance of the proposed method were compared with those of the conventional WPT system coil shielding topologies. The proposed shield exhibited about 27.37 dB more 3rd harmonic EMI suppression than other methods while maintaining higher power transfer efficiency.
Time-of-flight of solitary waves in dry and wet chains of beads: Experimental results and phenomenological models
Authors: Labbé Raúl , Vergara Lautaro , Olivares Ignacio
Published: May 2019

A highly nonlinear solitary wave is generated by impacting a dry chain of beads on one of its ends. Its speed depends on the speed v0 of the striker and the details of the contact force. The force on the bead at the site n = 7 and the end of the chain, as well as the time-of-flight (ToF) of both, the incident and reflected waves, is measured as a function of v0. This study was performed on a chain of stainless steel beads in two general cases: the dry chain and wet chains having three different types of oil on and around the contact points between the beads. The ToF displays a complex dependence on the fluid’s rheological properties not seen in previous studies. Power-law dependencies of the ToF on v0 in both, dry and wet, cases were found. It turned out that the Hertz plus viscoelastic interactions are not enough to account for the measured data. Two phenomenological models providing a unified and accurate account of our results were developed.
Improved contact resistivity and enhanced mobility of metal-graphene FET by inserting ultra-thin MoOx layer at source/drain region
Authors: Zhang Yuan , Qu Xin-Ping
Published: May 2019

Achieving low resistance contacts and high carrier mobility are common concerns for obtaining high performance of graphene devices. In graphene FETs (GFETs), the work functions (WF) of electrode materials and metal-graphene (M-G) contact configurations have remarkable influences on contact properties of M-G. In this work, the contact properties of Cu-G are improved prominently by inserting a nanoscale MoOx (x<3) ultra-thin layer formed by annealing Mo film in the air atmosphere at 150°C between the electrode and graphene in GFETs. Results show that MoOx can not only induce the p-doping, but also induce end contact to graphene characterized by Mo-C carbide formation from the XPS and TEM results. The relationship between the improvement of contact properties of M-G and the thickness of MoOx layer inserted at source/drain region was further investigated. It is shown that, within 0-3 nm thickness of MoOx, the thicker the MoOx deposited, the better the output characteristics and the greater the field mobilities are. The mechanism of that MoOx deposited at source-drain helps improving the carrier mobility is discussed and is related to improved interface between graphene and SiO2. This study provides a simple and important way to improve contact properties of M-G and carrier mobility of contact and graphene FET.
Self-sustaining thermophotonic circuits
Authors: Zhao Bo , Buddhiraju Siddharth , Santhanam Parthiban , Chen Kaifeng , Fan Shanhui
Published: May 2019

Significance

Photon-based systems that convert heat to electricity have been limited by low power density. Thermophotonic systems have the potential to significantly enhance the power density. This potential has not been realized in practice, due in part to the fundamental thermodynamic difficulty in designing a self-sustaining circuit that enables steady-state power generation. Current construction instead uses batteries which lower system efficiency and adds complexity. We overcome such difficulty by introducing an electronic circuit where multiple photons can be generated from a single electron. Our design enables a self-sustaining thermophotonic circuit that can achieve a steady-state power density exceeding traditional thermophotovoltaic systems by many orders of magnitude. This work highlights possibilities for constructing heat engines with light as the working medium.
A simple and versatile authenticity assay of coffee products by single-nucleotide polymorphism genotyping
Authors: Nakagawa Toshifumi , Doi Masanori , Nishi Kosuke , Sugahara Takuya , Nishimukai Hiroaki , Asano Migiwa
Published: May 2019

Interspecific single-nucleotide polymorphisms (SNPs) in the rbcL DNA barcode have been strictly validated and adopted as a designed SNP genotyping maker to discriminate between two major coffee species, Coffea arabica and C. canephora, and to estimate the mixing ratio of DNA from C. arabica/C. canephora in this study. The SNP genotyping is applicable to not only green (unroasted) coffee beans, but also processed coffee products (roasted coffee beans and instant coffee powder), in which genomic DNA is degraded, because the genotyping developed in this study requires only 10 copies of 63-bp-long DNA fragments of rbcL gene. The authenticity assay established in this study has several advantages: a high versatility to DNA sample conditions; simple and rapid procedures (only two steps; DNA extraction and SNP genotyping); the feasibility in coffee business for practical use to prevent false advertising and provide quality control.

Abbreviations: SNP: single-nucleotide polymorphism; SBS: single base substitution; ISR: intergenic spacer region; INDEL: insertion-deletion.
Expression and purification of recombinant serine protease domain of human coagulation factor XII in Pichia pastoris
Authors: Peng Bangya , Xue Guangpu , Xu Dongfang , Feng Zanjie , Chen Jing , Huang Mingdong , Lu Hongling , Gong Lihu
Published: May 2019

Human coagulation factor XII, the initiating factor in the intrinsic coagulation pathway, is critical for pathological thrombosis but not for hemostasis. Pharmacologic inhibition of factor XII is an attractive alternative in providing protection from pathologic thrombus formation while minimizing hemorrhagic risk. Large quantity of recombinant active factor XII is required for screening inhibitors and further research. In the present study, we designed and expressed the recombinant serine protease domain of factor XII in Pichia pastoris strain X-33, which is a eukaryotic expression model organism with low cost. The purification protocol was simplified and the protein yield was high (~20 mg/L medium). The purified serine protease domain of factor XII behaved homogeneously as a monomer, exhibited comparable activity with the human βFXIIa, and accelerated clot formation in human plasma. This study provides the groundwork for factor XII inhibitors screening and further research.