bluuebunny/crossref_metadata_2025 huggingface dataset:
Chiral metasurfaces formed by 3D-printed square helices: A flexible tool to manipulate wave polarization
Authors: Wu Shengzhe , Yachin Vladimir V. , Shcherbinin Vitalii I. , Tuz Vladimir R.
Published: September 2019

The transmission of linearly and circularly polarized waves is studied both theoretically and experimentally for chiral metasurfaces formed by arrays of metallic square helices. The helical particles of the metasurfaces are constructed of rectangular bars manufactured by direct three-dimensional printing in solid metals. The transmittance of the metasurface is found to depend critically on the number of bars forming the square helical particles. In the case of an even number of bars, the chiral metasurface exhibits identical co-polarized transmittance of orthogonal linearly polarized waves, which are characterized by a dual-band asymmetric transmission. For an odd number of bars, the metasurface provides the same cross-polarization conversion for any polarization orientation of the incident field and thus serves as a polarization-independent twist polarizer. Finally, the transmittance of this polarizer is investigated with respect to the dimensions of the square helices. The investigated chiral metasurfaces are characterized by strong broadband circular dichroism regardless of the number of bars in the helical particles. The wide variety of transmission properties observed in the metasurfaces makes them particularly attractive for use in polarization conversion and separation devices.
Diffusion and recombination of optically-injected carriers in a semiconductor wafer in 3-dimensions
Authors: Boyd Kevin M. W. , Kleiman Rafael N.
Published: September 2019

In this work, we derive a general equation describing the transmission of a probe beam in a pump/probe experiment upon optical injection of carriers into a semiconductor. The pump/probe radial overlap equation generalizes previous pump/probe approaches by considering the pump and probe beam sizes relative to each other and to the diffusion length. The pump/probe equation leverages a powerful solution to the free-carrier density under optical injection that is also derived in this work. The free-carrier density solution extends the work of Luke and Cheng to 3-dimensions, incorporating the effects of radial diffusion in a plane parallel to the semiconductor surface. The pump/probe equation quantifies the magnitude of free-carrier absorption of a probe beam induced by free-carriers optically injected via a pump beam. We show that when the pump/probe beams are much smaller than the carrier diffusion length, radial diffusion effects dominate. Measurements in this regime can be used to uniquely and simultaneously determine both the effective carrier lifetime and the diffusion coefficient. The equation agrees well with experimental measurements using a recently developed single-beam pump/probe technique, which ensures a perfect overlap of the pump and probe beams. Based on this equation, measurement criteria are developed for accurate determination of carrier lifetime and to correct for the effects of radial diffusion.
Magnetoelasticity of Co25Fe75 thin films
Authors: Schwienbacher Daniel , Pernpeintner Matthias , Liensberger Lukas , Edwards Eric R. J. , Nembach Hans T. , Shaw Justin M. , Weiler Mathias , Gross Rudolf , Huebl Hans
Published: September 2019

We investigate the magnetoelastic properties of Co25Fe75 and Co10Fe90 thin films by measuring the mechanical properties of a doubly clamped string resonator covered with multilayer stacks containing these films. For the magnetostrictive constants, we find λCo25Fe75=(−20.68±0.25)×10−6 and λCo10Fe90=(−9.80±0.12)×10−6 at room temperature, in contrast to the positive magnetostriction previously found in bulk CoFe crystals. Co25Fe75 thin films unite low damping and sizable magnetostriction and are thus a prime candidate for micromechanical magnonic applications, such as sensors and hybrid phonon-magnon systems.
Is the European red fox a vector of the invasive basket asparagus (Asparagus aethiopicus) in eastern Australia?
Authors: O'Connor Julie M. , Burrows David M. , Allen Benjamin L. , Burnett Scott E.
Published: September 2019

Basket asparagus (Asparagus aethiopicus) has become a naturalised invasive plant in some coastal areas of Australia since its introduction in the late 19th century. Its spread through garden waste dumping and avian seed dispersal has been well documented and both are considered to be the primary means of dispersal. While a small number of avian vectors have been identified, no Australian studies have investigated the potential of mammals to disperse basket asparagus seeds. We collected basket asparagus seeds from fox (Vulpes vulpes) scats collected in the field, confirmed the viability of these seeds in germination trials, and further documented the germination of basket asparagus seeds from an undisturbed fox scat in situ. These results demonstrate that foxes consume and disperse basket asparagus seeds, and that these seeds are viable and germinate under field conditions. Foxes not only use basket asparagus stands as harbour, but can also facilitate the plant’s dispersal in coastal ecosystems.
Critical reflection for researcher–community partnership effectiveness: the He Pikinga Waiora process evaluation tool guiding the implementation of chronic condition interventions in Indigenous communities
Authors: Rarere Moana , Oetzel John , Masters-Awatere Bridgette , Scott Nina , Wihapi Ray , Manuel Carey , Gilbert Rewa
Published: September 2019

Critically reflecting on researcher–community partnerships is a key component in implementing chronic condition interventions in Indigenous communities. This paper draws on the results and learnings from a process evaluation that measures how well two research–community partnerships have followed the He Pikinga Waiora (HPW) Implementation Framework while co-designing chronic condition interventions in primary care. The HPW framework is centred on Indigenous self-determination and knowledge surrounded by community engagement, cultural centredness, systems thinking and integrated knowledge translation. The evaluation included in-depth interviews and online surveys with 10 team members. The findings demonstrate that the HPW framework was followed well, with strengths particularly in community engagement and relationship building. Areas for improvement included systems thinking and integrated knowledge translation to support sustainability of the interventions. The need for partnerships to use process evaluation results to support critical reflection is asserted, which helps build strong trust and synergy, power sharing and effective and sustainable implementation practices. It is concluded that the HPW framework is well suited to evaluating implementation of health interventions in primary care as it assists in the facilitation of better collaboration between researchers and Indigenous communities, and encourages the implementation team to reflect on power and privilege.
Attack robustness and stability of generalized k-cores
Authors: Shang Yilun
Published: September 2019

Earlier studies on network robustness have mainly focused on the integrity of functional components such as the giant connected component in a network. Generalized k-core (Gk-core) has been recently investigated as a core structure obtained via a k-leaf removal procedure extending the well-known leaf removal algorithm. Here, we study analytically and numerically the network robustness in terms of the numbers of nodes and edges in Gk-core against random attacks (RA), localized attacks (LA) and targeted attacks (TA), respectively. In addition, we introduce the concept of Gk-core stability to quantify the extent to which the Gk-core of a network contains the same nodes under independent multiple RA, LA and TA, respectively. The relationship between Gk-core robustness and stability has been studied under our developed percolation framework, which is of significance in better understanding and design of resilient networks.
Solar-powered mini-grids and smart metering systems, the solution to Rwanda energy crisis
Authors: Dieu Niyonteze Jean De , Zou Fumin , Osarumwense Asemota Godwin Norense , Bimenyimana Samuel
Published: September 2019

As the population and economy of Rwanda continue to grow, the energy consumption in Rwanda has shown a continuous rise correspondingly to the population and modern socio-economic life desired in the past few decades. According to the Ministry of Infrastructure, Rwanda household access to electricity increased to 52% by September 2018. Not only does 48% of Rwanda’s population have no electricity, but also the grid is not stable where persistent power failures occur. However, the government has invested in the power sector in order to achieve 100% access to electricity for all population by 2024.To ensure that the country gets affordable and reliable power supply, it needs very strong energy sector’s projects, policy and private partners to achieve these objectives. In this paper, policy and semi-private operator model were proposed where solar-powered mini-grids and smart metering systems will provide a sustainable solution to the energy crisis by increasing electricity reliability and providing power to different energy consumers. The challenges discussed include community engagement, financial and technical. The focus is on the partnership between the government through local people and private partners by maximizing investor attraction, mutual profitability, intense model and reliable or inexpensive energy for the population. The continuation of policy supports would be necessary for this century to maintain and enhance the growth of solar energy in this country which is the essential strategy for rural electrification, for climate change and low carbon footprint development.
Analysis and evaluation of power system voltage stability considering pumped storage power station
Authors: Yu Yue , Jin Long , Li Yanjun , Liu Longhao , Liu Guangye
Published: September 2019

Aiming at the influence of the connection of pumped storage power station to power grid on voltage stability, the impedance modulus margin defined by non-linear equivalent analysis method is used as the evaluation index of system voltage stability, and a method for evaluating power system voltage stability considering pumped storage power station is proposed. Considering the peak-cutting function of pumped storage power station, the calculation method of general impedance modulus margin of load nodes is derived. The general impedance modulus margin of load nodes is calculated by changing the output and access position of pumped storage power station, and its influence on the voltage stability of power system is analyzed. Coordinating the access position and output of pumped storage power station to improve the voltage stability of the system. Finally, through the simulation calculation on the standard node system, the feasibility of the project is verified.
Application of an improved harmonic detection algorithm in harmonic control of charging station
Authors: Kunfeng Zhang
Published: September 2019

With the rapid prosperity of the electric vehicle industry, the demand for charging stations providing charging services has become increasingly strong, which followed by serious power quality problems. Because the current level of the charging station changes gradually with time, the harmonic current generated by the charging station will also change gradually with time. The influence of the low-pass filter leads to the slow start-up and tracking speed of harmonic current detection method based on ip-iq algorithm, which cannot meet the need of harmonic control in charging station. In this paper, the harmonic characteristics and basic structure of six-pulse rectifier charging pile are analyzed in detail, and the charging station model based on six-pulse rectifier charging pile is established. At the same time, in order to meet the need of harmonic suppression, a harmonic current detection algorithm based on variable step size LMS/LMF algorithm is proposed and analyzed comprehensively. The simulation and experimental results show that compared with the traditional harmonic detection algorithm, the improved harmonic detection algorithm has obvious advantages in many aspects, such as start-up and tracking speed, and has good engineering application prospects.
Research on error mechanism analysis and compensation method of Fiber-Optical Current Transformer
Authors: Li Dengyun , Lei Min , Zhang Dandan , Mo Shi , Chai Yongfeng
Published: September 2019

The structure of Fiber-Optical Current Transformer (FOCT) is completely different from that of traditional electromagnetic transformer, and the error analysis method is quite different from that of traditional transformer. However, there is no systematic calculation method for the error of FOCT at present. Starting from the working principle and structure of fiber-optical current transformer, this paper theoretically analyses and deduces all kinds of error sources of FOCT, puts forward the error calculation method of FOCT, calculates the overall error based on the actual parameters of a 200 kV Fiber-Optical Current Transformer, and proposes a method to compensate the measurement error of FOCT by changing the initial phase angle of λ/4 wave plate. The initial phase angle of the λ/4 wave plate with the best error compensation effect is 86 degrees.
Dynamic simulation model of Fiber Optical Current Transformer considering error factors
Authors: Li Dengyun , Li He , Zhang Dandan , Mo Shi , Chai Yongfeng
Published: September 2019

The paper studies and establishes the dynamic model of fiber optical current transformer by MATLAB. The equivalent model of FOCT’s digital closed loop control system is created by reasonably simplifying deviation and feedback of FOCT. By analyzing the four components of FOCT’s main sources of error, 10 factors that cause FOCT measurement errors are obtained. Then the variable 10 error parameters are introduced into the model to establish a dynamic model of fiber optical current transformer considering the error factor. The model can evaluate the performance of the fiber optical current transformer by using the variable FOCT’s error parameters, Also, model dynamically combines the FOCT’s related parameters and environmental factors with the transformer’s transfer characteristics and reflects the influence of FOCT error factors on FOCT performance.
Parameter design and electromagnetic field analysis of electromagnetic biased axial magnetic bearing
Authors: Kong Ruijie , Mei Lei
Published: September 2019

A type of electromagnetic biased axial magnetic bearing is studied. Compared with traditional axial magnetic bearings, it has a smaller external diameter of the thrust plate, which is helpful to improve the critical speed of the rotor in theory. The structural parameters are obtained and finite element model(FEM) is established. The magnetic flux leakage coefficients and the magnetic resistances are calculated. The rationality of parameter design is verified. The results show that the parameter design and the electromagnetic field simulation are in accordance with rationality of the design. Therefore, the magnetic biased axial magnetic bearing is not only simple in structure, but also reasonable in design, which is of great significance to the design of magnetic bearing.
Logistics analysis and simulation in the intelligent manufacturing workshop
Authors: Ni Ping , Wang Yunxia , Chen Di
Published: September 2019

This paper aims to study the internal logistics system of manufacturing enterprises, and use the logistics analysis and modeling methods to plan and simulate the layout of the workshop. Firstly, the SLP (Systematic Layout Planning) method is planned for a specific enterprise. Secondly, the Flexsim software and the ExSpect software are used to simulate the logistics of the planned workshop. The Flexsim software is used to know the facility utilization rate, and the cause of the blockage is analyzed. The improvement measure of adding one casting machine and static furnace is proposed to solve the problem of equipment blockage. The modeling and analysis of the workshop is carried out in combination with Petri net, and the total working hours of production and processing are obtained through ExSpect software simulation.
Diagrams of seasonal and daily hot water consumption by apartment buildings (ab) in the moscow region
Authors: Vasilyev Gregory , Popov Mikhail , Dmitriev Alexander , Vasileva Olga , Kolesova Marina
Published: September 2019

The article presents an analysis of hot water consumption in apartment buildings of the Moscow region. This study was conducted based on monitoring actual data on hot water consumption by apartment buildings (AB) in Moscow and the Moscow region. The results were used to develop a computational model for the daily use of hot water in apartment buildings.
A 43%@0.1V efficiency self-sustaining solar energy harvester in indoor lighting
Authors: Yu Deng-Bang , Liu Xin-Ning , Chen Jing
Published: September 2019

This paper presents a self-sustaining solar energy harvester (EH) based on 130nm process, which consists of a low voltage cold start (CS) circuit and a high efficiency boost charger. The CS circuit makes the boost charger self-sustaining and start the boost circuit from the 100mV input. An adaptive switch frequency modulation (SFM) and switch capacitor modulation (SCM) are proposed to minimize the switch loss and conduction loss of boost charger, thus reduce overall circuit power consumption. The proposed boost charger utilizes a dual voltage technique for reducing the power dissipation of the internal circuit. The efficiency of the boost charger ranges from 43% at V

IN
= 100mV to 65% at V

IN
= 300mV.
Progress toward Barium Tagging in High Pressure Xenon Gas with Single Molecule Fluorescence Imaging
Authors: Byrnes N. , Foss F. W. , Jones B.J.P , McDonald A.D. , Nygren D.R. , Thapa P. , Trinidad A.
Published: September 2019

We present an update on the development of techniques to adapt Single Molecule Fluorescent Imaging for the tagging of individual barium ions in high pressure xenon gas detectors, with the goal of realizing a background-free neutrinoless double beta decay technology. Previously reported progress is reviewed, including the recent demonstration of single barium dication sensitivity using SMFI. We then describe two important advances: 1) the development of a new class of custom barium sensing fluorescent dyes, which exhibit a significantly stronger response to barium than commercial calcium sensing compounds in aqueous solution; 2) the first demonstration of a dry-phase chemosensor for barium ions. This proceeding documents work presented at the 9th Symposium on Large TPCs for Rare Event Detection in Paris, France.
The search for light dark matter with the NEWS-G spherical proportional counter
Authors: Giroux G. , Gros P. , Katsioulas I.
Published: September 2019

The NEWS-G (New Experiment with Spheres - Gas) collaboration searches for dark matter in the form of low-mass Weakly Interacting Massive Particles (WIMPs) using Spherical Proportional Counters (SPCs) filled with gases with low atomic masses. The operation of SEDINE, a 60-cm diameter prototype SPC filled with a mixture of neon and methane and installed at the Laboratoire Souterrain de Modane (LSM) in France, recently set new constraints on the spin-independent WIMP-nucleon scattering cross-section in the sub-GeV/c2 mass region. The collaboration is currently planning the installation a 140-cm ultra-low background SPC in a compact shielding at SNOLAB in Canada. Recent advances in radioactive background control, detector monitoring and sensor development, will provide for this next experimental phase of NEWS-G unprecedented sensitivity to low-mass WIMPs.
Gas and copper purity investigations for NEWS-G
Authors: Knights P.
Published: September 2019

In the search for low mass dark matter particles the NEWS-G collaboration utilises the spherical proportional counter, a novel detector concept. Currently, the next stage of the experiment, NEWS-G@SNOLAB, is under preparation. The choice and processing of construction materials and gases are of paramount importance for the minimisation of experimental backgrounds. The effect of impurities on detector performance, both regarding the gas and construction materials, is presented and the efforts undertaken to maximise the sensitivity of the experiment are discussed. In particular, the method of electroplating a cladding-type ultra-pure copper layer on the inner surface of the detector is detailed and preliminary results are presented.
PICOSEC-Micromegas: Robustness measurements and study of different photocathode materials
Authors: Sohl L , Bortfeldt J , Brunbauer F , David C , Desforge D , Fanourakis G , Franchi J , Gallinaro M , García F , Giomataris I , González-Díaz D , Gustavsson T , Guyot C , Iguaz F J , Kebbiri M , Kordas K , Legou P , Liu J , Lupberger M , Manthos I , Müller H , Niaouris V , Oliveri E , Papaevangelou T , Paraschou K , Pomorski M , Qi B , Resnati F , Ropelewski L , Sampsonidis D , Schneider T , Schwemling P , Scorsone E , van Stenis M , Thuiner P , Tsipolitis Y , Tzamarias S E , Veenhof R , Wang X , White S , Zhang Z , Zhou Y
Published: September 2019

Detectors with a time resolution of 20-30 ps and a reliable performance in high particles flux environments are necessary for an accurate vertex separation in future HEP experiments. The PICOSEC-Micromegas detector concept is a Micro-Pattern Gaseous Detector (MPGD) based solution addressing this particular challenge. The PICOSEC-Micromegas concept is based on a Micromegas detector coupled to a Cherenkov radiator and a photocathode. In this detector concept, all primary electrons are initiated in the photocathode and the time jitter fluctuations are reduced. Different resistive anode layers have been tested with the goal of preserving a stable detector operation in a high intensity pion beam. One important characteristic of a gaseous detector in a high flux environment is the ion backflow (IBF). That can cause damage to more fragile photocathode materials like CsI. Various types of photocathode materials have been tested in order to find a robust solution against IBF bombardment.
Muon tomography with Micromegas: Archaeology, nuclear safety and new developments for Geotechnics.
Authors: Gómez H. , Attié D. , Calvet D. , Coppolani X. , Gallois B. , Kebbiri M. , Lehuraux M. , Magnier P. , Mandjavidze I. , Procureur S. , Vandenbroucke M.
Published: September 2019

Muon tomography, or muography, stands out as a non-invasive technique for the scanning of big objects’ internal structure. It relies on the measurement of the direction changes or absorption of atmospheric muons when crossing the studied object. Proposed several decades ago, the performance achieved in particle detectors in the last years, specially in terms of stability, robustness and precision, has enlarged the possible applications of this technique. Bulk Micromegas represent a well-known technology suitable for the construction of muon telescopes based on these detectors. Thus autonomous and portable instruments have been conceived and constructed at Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA), being able to perform muography measurements in-situ, next to the studied objects. At present, a new muon telescope concept is being developed at CEA, combining a Time Projection Chamber (TPC) readout by a 2D multiplexed bulk Micromegas. This new generation of detectors will enlarge the possible application fields of muography, being specially interesting for geotechnics.
Vacuum characteristics of magnetorheological elastomers
Authors: Bazinenkov A M , Khanbekov I F , Rotar’ A P , Ivanova D A , Mikhailov V P
Published: September 2019

A model of gas evolution from the surface layer of a magnetorheological (MR) elastomer, which is a promising material for use in vacuum systems, is described. The results of research of the partial composition of gases exhaled from the MR elastomer for different heating temperatures depending on the pumping time are given.
New method of ultra low gas flow control
Authors: Emelianenko R O , Deulin E A
Published: September 2019

The paper considers the new method of ultralow gas flow control realized with the leak specimen.
Method of creating equivalent circuits of capacitive batteries of pulsed power supplies of powerful technological systems
Authors: Goncharov V D , Yashkardin R V , Volynov A M
Published: September 2019

The article is devoted to the design aspects of pulsed power supplies of technological systems. Experiments had shown that development of such power supplies requires to take into account the resistive and inductive components of the complex impedance of capacitors batteries. The article proposes a method for finding the equivalent circuit of these batteries. The method is based on an approximation of their experimentally measured frequency characteristics. The article also shows that the obtained results for a single battery cannot be distributed to capacitor bank. Presented numerical simulation results shows that the duration of the pulse front depends on the inductive component of the resistance of capacitive elements.
Test results for approval of the type of installation for reproduction of micro-flows of gases in vacuum
Authors: Kologov A V , Gorobei V N , Chernyshenko A A
Published: September 2019

The article presents data on the composition and principle of operation of the unit of reproduction of micro-flows of gases in vacuum, as well as the results of its tests for the purpose of type approval on the state secondary (working) standard unit of gas flow in vacuum.
Determination of the threshold sensitivity of a deposited dielectric film thickness control method based on surface plasmon resonance effect
Authors: Komlev A E , Dyukin R V , Shutova E S
Published: September 2019

The lower boundaries of the real time measuring range of the dielectric film thickness on the sensor surface, the principle of which is based on the effect of the excitation of surface electromagnetic waves (SEW), are determined. The simulation was performed for materials with high and low refractive index.
Modelling of the cathode spots motion on the surface of the cathode
Authors: Kostrin D K , Martsinukov S A
Published: September 2019

The paper considers the recreation of the cathode spot motion on the cathode exterior in the COMSOL Multiphysics program. The results demonstrate the adequacy of the physic-mathematical model used in this work.
Reduction of hydraulic resistance in vacuum columns as an effective tool in the formation of energetic rectification units
Authors: Leontiev V S , Romanova N A
Published: September 2019

Using an example of ethylbenzene and diethylbenzene separation, we demonstrate that structured packing with a low specific flow resistance is an effective tool for setting up hardware and energy rectification packages. By replacing conventional plates with structured packing, the flow resistance and vertical temperature gradient are significantly lowered, providing favorable conditions for thermal coupling of the columns. Thermal coupling of the columns in a two-column setup for extraction of rectified ethylbenzene and diethylbenzene provides heating steam savings of 0.13 Gcal per tonne of diethylbenzene.
Development of the automated vacuum test bench for altimeters
Authors: Lillo A V , Stotckaia A D
Published: September 2019

The work is devoted to study characteristics of the compact vacuum test bench, a feature of which is the presence of a programmable control system. During the work, the stages of assembly of the stand and technical requirements are described. Studies are being conducted to assess the build quality of the stand and the operation of the control system.
Computer simulation of nano-thin film condensation process in a vacuum
Authors: Su Chu Trong , Tupik V A , Potapov A A , Margolin V I
Published: September 2019

In this paper, the role of nano-thin film condensation process in thin film technology is shown. It was demonstrated by using the computer simulation method that the abovementioned process determines the quality of the thin film. Proprietary models were used in order to analytically calculate the condensation process of a particle on the potential field of ideal crystal substrate and to simulate the processes of condensation and growth for atoms with isotropic or anisotropic bonds with other atoms. The numerical method is based on the algorithm of a random chosen active atom, the direction of motion of this atom is calculated by the quasi-Newton method and the step of atom movement is considerably shorter than the optimal distance of two atoms.
Rationality evaluation index of asphalt molecular model
Authors: Zhu Jianyong , Zhou Chao
Published: September 2019

In terms of the diversity and complexity of current molecular models of asphalt, this paper proposes the solubility parameter as the evaluation index of asphalt component rationality. The solubility parameters of 22 asphaltenes average molecular models, 3 aromatics average molecular models, 3 saturates average molecular models and 4 resins average molecular models were calculated, according to the principle of similar compatibility, reasonable molecular models of the average asphalt component were selected. A molecular model of asphalt was established based on a four-component test. The glass transition temperature was used as the evaluation index, and the temperature difference between the molecular simulation and the DSC test was less than 1 °C.
A Sticky Situation: Poor Correlation Between Platelet Inhibition Assays
Authors: Dean Christina L , Duncan Alexander , Ingle Ann , Guarner Jeannette , Roback John D , Sullivan Harold C , Maier Cheryl
Published: September 2019

Monitoring antiplatelet therapy is critical in patients undergoing cardiac or neurologic stent placement to ensure adequate platelet suppression and prevent thrombosis. Light transmission aggregometry (LTA) using platelet-rich plasma (PRP) is the gold standard to assess platelet responsiveness to aspirin (ASA) and P2Y12 inhibitors (P2Y12-I). Other platforms for antiplatelet therapy monitoring employ whole-blood aggregometry (WBA) via electrical impedance (EA) or ELISA-based detection of urinary metabolites. The goal of this study was to evaluate the concordance of four antiplatelet therapy monitoring platforms. Blood and urine samples from 20 patients receiving antiplatelet therapy prior to neurologic stent placement were prospectively collected. Blood samples were analyzed by LTA using PRP on the Helena AggRAM and by WBA-EA using the Chrono-log Lumi-aggregometer to assess ASA and P2Y12-I response. For the LTA, the maximum amplitude (MA) of the platelet aggregation curve was determined using high-dose (HD) and low-dose (LD) ADP agonist for measuring P2Y12-I response and with arachidonic acid (AA) for ASA response. For the WBA, resistance (ohms) was measured with ADP for P2Y12-I response and with HD and LD collagen for ASA response. Whole-blood samples were also analyzed with the VerifyNow PRUTest to assess platelet response to P2Y12-I. Urine samples were analyzed with AspirinWorks. Concordance of antiplatelet response based on predefined cutoff values (eg, concordant = optimal/optimal, discordant = optimal/suboptimal), as well as correlation between actual units of measure, was determined. When comparing P2Y12-I response determined by LTA and WBA, overall concordance was 55% (correlation was r = 0.75 and 0.65 for HD and LD ADP, respectively). VerifyNow was concordant with LTA in 70% (r = 0.86 and 0.75 for HD and LD ADP, respectively) and with WBA in 45% (r = 0.57) of samples. When comparing ASA response between LTA and WBA, overall concordance was 70% (r = 0.09 and 0.19 for HD and LD collagen, respectively). AspirinWorks was concordant with LTA and WBA in 60% of samples (r = 0.32 for LTA; r = 0.08 LD collagen, r = 0.02 for HD collagen on WBA). In summary, concordance varied between 45% and 70% on the four antiplatelet therapy monitoring platforms. Testing of P2Y12 inhibition showed the best correlation between LTA HD ADP and VerifyNow (r = 0.86). When comparing WBA vs LTA, the strongest correlation was between LD ADP LTA and WBA (r = 0.75). Correlation with ASA inhibition was overall poor between the various assays (r ranging between 0.02 and 0.58). The results from this correlation study support the continued use of LTA with HD and LD ADP and AA; other testing methods can be used as adjuncts when LTA proves difficult to interpret.
Limited Utility of Flow Cytometry Immunophenotyping for Assessment of Plasma Cells in Hematopoietic Progenitor Cell Apheresis Product From Patients With Multiple Myeloma
Authors: Cheng Yao , Li Shiyong
Published: September 2019

Aim

Flow cytometric immunophenotyping (FCI) is routinely performed in our laboratory to assess the clonality of plasma cells in hematopoietic progenitor cell apheresis (HPC-A) products as part of the quality control for multiple myeloma patients undergoing autologous stem cell transplantation. The purpose of this project is to investigate whether FCI is indicated for HPC-A when FCI is also performed on a bone marrow biopsy sample obtained before or after HPC-A collection.

Materials and Methods

The FCI results of HPC-A samples were retrieved from the laboratory database and analyzed. Relevant FCI results of the corresponding bone marrow biopsy samples were also retrieved and analyzed. All FCI was performed using BD FACSCalibur/FACSCanto with a four-color antibody panel, and the listmode data were analyzed by BD FACSDiva.

Results

FCI was performed on a total of 1,621 HPC-A samples in our laboratory from 02/01/2012 to 02/02/2018. A total of 58 HPC-A samples were positive for a monoclonal plasma cell population (3.8% of the total sample). Among those positive samples, 55 had bone marrow biopsy done before or after HPC-A collection: 38 within a month, 8 between 1 and 2 months, and 9 between 3 and 6 months. Fifty-four of 55 bone marrow samples were positive for a monoclonal plasma cell population by FCI.

Conclusion

The utility of FCI in the quality assessment of HPC-A products from patients with multiple myeloma is a very limited when FCI is performed on a bone marrow biopsy obtained within 6 months of HPC-A collection.
Widespread Use of High-Dose Ceftriaxone Therapy for Uncomplicated Gonorrhea Without Reported Ceftriaxone Treatment Failure: Results From 5-Year Multicenter-Surveillance Data in China
Authors: Liu Jun , Han Yan , Yin Yueping
Published: September 2019

Background

Antimicrobial resistance (AMR) to N gonorrhoeae has emerged for each of the antibiotics following their introduction into clinical practice recommended as first-line therapies. To improve rational and effective clinical antibiotic treatment, we analyzed the prescription patterns of antibiotics and its therapeutic effect in the treatment of uncomplicated gonorrhea in China.

Methods

We obtained data from a follow-up multicenter surveillance program. Multinomial logistic regression analyses were conducted to explore the associations between demographic/clinical variables with the levels of sensitivity to ceftriaxone and prescription of high-dose ceftriaxone.

Results

In this study, 1,686 patients infected with N gonorrhoeae were recruited in a surveillance network during the period of January 1, 2013, through December 31, 2017, in seven hospitals distributed in five provinces. The prevalence of isolates with decreased susceptibility to ceftriaxone was 9.8% (131/1333), fluctuating between 5.6% and 12.1%. Injectable ceftriaxone was chosen as the first-line treatment among 83.1% patients, and most of them (72.7%, 1,018/1,401) received more than a 1,000-mg dosage. Patients who were infected with gonorrhea or infected with other STDs before (AOR 1.611, 95% CI [1.103-2.352]; AOR 2.329, 95% CI [1.553-3.494]) or who used already antibiotics for this infection (AOR 1.597, 95% CI [1.04-2.452]) were associated with higher prescribed ceftriaxone dosage prescribed. All of the patients recruited in this study were cured regardless of the isolates’ susceptibility to ceftriaxone or the dosage of ceftriaxone they received.

Conclusions

No failure treatment for uncomplicated gonorrhea was reported in China; however, high-dose ceftriaxone was widely used in China, and its impacts need further studies.
A Center-Wide Study of D-Dimer Testing for Pulmonary Embolism in the ED Setting
Authors: Balakrishnan Ridin , Hu Shaomin , Gil Morayma Reyes
Published: September 2019

Pulmonary embolism (PE) is a life-threatening condition associated with a very high mortality. While its diagnosis remains challenging, the use of diagnostic tests has increased tremendously. There are many different guidelines used to work up suspected PE. The Wells and/or Geneva scores are used to estimate the pretest probability (PTP) of PE before any complementary testing is done. While a CT pulmonary angiography (CTPA) should not be performed in individuals with a low/intermediate PTP and a negative D-dimer (DD), some data suggest that up to 55% of patients with low PTP undergo a CTPA, even though they might not have had a DD or had a negative DD. As such, in this study, we wanted to evaluate the use of DD in our emergency department (ED). A pilot study was conducted using an interactive software developed in-house for the evaluation of health care quality, efficiency, and effectiveness. The EMR database (EPIC) we use consists of laboratory, clinical, pathological, and radiological reports, allowing us to use different search criteria and to outline cutoff values for continuous and categorical variables while permitting us to define a timeframe for the different observations. We looked at all ED visits in the period from 2014 to 2018 in which CTPAs were done for suspected PE. A total of 8,873 ED visits from 2014 to 2018 had a CTPA done for suspected PE. Of these, 6,117 cases had no DD done and 1,812 had a DD done along with CTPA. The high percent of visits with imaging done without a DD (69%) is justified if these are all cases with a high PTP (DD not indicated). If this assumption was true, then we expected a high percent of positive confirmation of PE by imaging. However, only 11% of these cases showed positive findings of PE. This rate is similar to published studies in many US hospitals that demonstrate overuse of CT owing to a lack of using the PTP-based approach. On the other hand, a vast majority of cases in our study with normal DD (<0.5 μg/L) had negative CT results (98%). Interestingly, all four cases that had positive PE findings by CT despite a negative DD (2%) were women (three below the age of 62 with chronic and/or subsegmental PE and one 47-year-old with a DD = 0.49 μg/L). This finding calls for consideration of age and possibly gender-based DD reference ranges. Lastly, while CTPA is considered the gold standard for PE diagnosis, it has limitations: cost, increased length of stay, unnecessary exposure of radiation, contrast, and unnecessary treatment of subsegmental PE. Therefore, an approach using PTP and using DD appropriately is warranted in order to prevent patients from being exposed to unnecessary risks and also to reduce costs.
Effects of Biotin Supplements Ingestion on Beckman Biotinylated Immunoassays
Authors: Cao Liyun , Scott Donna , Hardy Robert
Published: September 2019

Background

Biotin is a water-soluble B vitamin with high affinity for streptavidin binding. The biotin-streptavidin amplification strategy is widely used to increase the analytical sensitivity of clinical laboratory tests, which are also vulnerable to biotin interference. The aim of this study is to evaluate the effects of the orally taken biotin supplements on Beckman biotinylated immunoassays.

Methods

Twelve volunteers were recruited to ingest a single dose of 10 mg biotin after fasting of multivitamin supplements for 3 days. Blood samples were collected at 0, 0.5, 1, 2, and 4 hours postingestion. Eleven biotinylated and nonbiotinylated immunoassays were performed on Beckman DXI and on Abbott Architect as a comparison.

Results

Ingestion of a single dose of 10 mg biotin caused falsely high values in biotinylated competitive immunoassays such as free triiodothyronine (fT3), total T3 (TT3), and free thyroxine (fT4) assays and falsely low values in biotinylated sandwich immunoassays such as thyroglobulin (Tg) and GI 19-9. The interference started at 0.5 hour postingestion, peaked at 1 hour postingestion, and continued at 4 hours postingestion. The extent of interference is different among these analytes. TT3 showed a maximum of a 219% increase of concentration, while GI 19-9 showed a maximum of a 25% decrease of concentration. fT3, fT4, and Tg showed intermediate changes of concentrations. The interference was not seen in nonbiotinylated immunoassays performed on Beckman DXI or Abbott Architect.

Conclusions

Single dose of biotin ingestion at the dosage of over-the-counter supplements can induce significant interference in certain biotinylated immunoassays and lead to incorrect test results.
A Laboratory Investigation in Response to Clinical Concern Regarding Heparin-PF4 ELISA Accuracy
Authors: Carll Timothy , Wool Geoffrey
Published: September 2019

Heparin-induced thrombocytopenia (HIT) is an immune-mediated disease that confers increased risk of thromboembolism to some patients receiving heparin. Usual evaluation of HIT entails a combination of clinical assessment (“4T” score), screening assay for anti-PF4 antibodies, and confirmatory functional assays, most commonly 14C-serotonin release assays (SRAs). At this academic medical center, clinician perception of increasing positivity on the screening ELISA raised concern for testing false positivity or a locoregional increase in HIT incidence. In response, we reviewed all anti-PF4 IgG/A/M ELISA testing for UChicago Medicine patients in a 3.5-year period in order to assess the accuracy of this assay in comparison to gold-standard SRA testing. ELISA results were categorized as negative (<0.400 OD), weakly positive (≥0.400 but <1.000 OD), or strongly positive (≥1.000 OD). During the same interval, all instances of confirmatory testing in a heparin-induced serotonin release system were compiled and scored by result as negative (<20% release difference with low-dose [0.1 U/mL] heparin and no apparent inhibition by high-dose [100 U/mL] heparin), borderline (<20% release difference with low-dose heparin, with 8% or more inhibition by high-dose heparin), and positive (>20% release with low-dose heparin, together with inhibition of release [<20%] with high-dose heparin). Both ELISA and SRA testing were stratified by month of order to highlight temporal trends. In total, 1,657 instances of anti-PF4 ELISA testing were studied, of which 298 were weakly positive and 166 were strongly positive (464 total abnormal ELISA). There were 348 instances of SRA testing, of which 50 were positive and 7 were borderline (57 total abnormal SRA). Of note, there were no instances wherein a negative ELISA test was followed by a borderline or positive SRA test. Over the most recent 4-month interval, a slight increase in the percentage of ELISA positivity was observed. A concordant increase in the number of positive SRA tests was also observed. There was no evidence of an increased rate of discrepancy between the two testing platforms, suggesting that this change does represent a locoregional increase in HIT cases. We took this opportunity to evaluate our ELISA testing sensitivity, specificity, and positive and negative predictive values and found them to be similar to previously published metrics. Given SRA testing as a gold-standard metric, this suggests a local sensitivity and negative predictive value of 100%. As expected, a strongly positive PF4 result was found to be a stronger predictor of a borderline or positive SRA result (39.8% PPV) than was a weakly positive PF4 result (4.5% PPV). As a note of caution, however, one patient had a weakly positive PF4 ELISA result and 100% release on SRA testing.
Metagenomic Characterization of Influenza Virus: Bacteria Super-Infections Associated With Death and Survival
Authors: Klonoski Josh , Williams Matthew , Huber Victor
Published: September 2019

Bacterial super-infections (BSIs) increase morbidity and mortality during influenza epidemics and pandemics, but not all strains of influenza virus uniformly increase host susceptibility to BSIs. Infection of mice with a swine virus isolate, A/swine/Texas/4199-2/98-H3N2 (TX98), did not significantly predispose the host to BSI mortality regardless of whether the BSI was caused by S aureus, S pneumoniae, or S pyogenes. Comparison of this survival phenotype with the laboratory influenza virus strain A/Puerto Rico/3/1934-H1N1, which demonstrates lethal synergism, showed that cellular recruitment profiles and cytokine responses differ between the two viruses in a manner that implicates host responses against the invading virus as a contributor to secondary infection severity. To better understand host, viral, and bacterial responses underlying disparate outcomes, we utilized metagenomic analysis of 559 genes, the NanoString nCounter Immunology Panel-Plus kit and FFPE mouse lungs from a published BSI time course. Results show an overall increased level of gene expression during BSIs associated with survival when compared to peak viral titers. Early viral clearance and the presence of S pyogenes in the lungs of TX98-infected lungs 24 hours after BSI was confirmed. Host responses tied to differences in early viral detection and clearance consisted of RIG-I, OAS, TLR3, TLR8, and TLR9. Key changes were noted in the expression of type I and II interferons, complement proteins, cytokines, chemokines, Fc receptors, scavenger receptors, the immunoproteasome, and genes associated with T, B, Treg, and NK cell activation. Interestingly, there was no significant increase in host antimicrobial peptides during BSIs associated with survival while CAMP and Nos2 were significantly increased 24 hours prior to death in lethal BSIs. To our knowledge, this is the first side-by-side metagenomics study of influenza BSIs associated with death and survival. Results offer mechanistic insight into clinical outcomes.