Current Circulation Research Articles

SARS-CoV-2 Permissive glioblastoma cell line for high throughput antiviral screening

Despite the great success of the administered vaccines against SARS-CoV-2, the virus can still spread, as evidenced by the current circulation of the highly contagious Omicron variant. This emphasizes the additional need to develop effective antiviral countermeasures. In the context of early preclinical studies for antiviral assessment, robust cellular infection systems are required to screen drug libraries. In this study, we reported the implementation of a human glioblastoma cell line, stably expressing ACE2, in a SARS-CoV-2 cytopathic effect (CPE) reduction assay. These glioblastoma cells, designated as U87.ACE2+, expressed ACE2 and cathepsin B abundantly, but had low cellular levels of TMPRSS2 and cathepsin L. The U87.ACE2+ cells fused highly efficiently and quickly with SARS-CoV-2 spike expressing cells. Furthermore, upon infection with SARS-CoV-2 wild-type virus, the U87.ACE2+ cells displayed rapidly a clear CPE that resulted in complete cell lysis and destruction of the cell monolayer. By means of several readouts we showed that the U87.ACE2+ cells actively replicate SARS-CoV-2. Interestingly, the U87.ACE2+ cells could be successfully implemented in an MTS-based colorimetric CPE reduction assay, providing IC50 values for Remdesivir and Nirmatrelvir in the (low) nanomolar range. Lastly, the U87.ACE2+ cells were consistently permissive to all tested SARS-CoV-2 variants of concern, including the current Omicron variant. Thus, ACE2 expressing glioblastoma cells are highly permissive to SARS-CoV-2 with productive viral replication and with the induction of a strong CPE that can be utilized in high-throughput screening platforms.

HF Radar Observations of Wintertime Surface Currents Over Hecate Strait, British Columbia

ABSTRACT An oceanographic high-frequency radar system was deployed by Fisheries and Ocean Canada along Hecate Strait, British Columbia to strengthen regional marine safety, including search-and-rescue operations. The Hecate Strait CODAR system provides hourly surface currents on a grid that spans central-northern Hecate Strait at a horizontal resolution of 5 km. These observations are used to characterize regional tidal currents and the subtidal wintertime surface circulation. The HF radar currents are also used to assess results from the Coastal Ice Ocean Prediction System for the West Coast of Canada (CIOPS-W), a component of the pan-Canadian operational ocean modelling system. Comparisons of rotary spectra and tidal current ellipses with historical current metre observations show that vector currents from the Hecate Strait CODAR system are reasonably accurate and can be used to describe the circulation and variability of ocean currents over the strait on tidal and subtidal time scales. Variability of the subtidal flow, in particular the along-strait surface-layer transport, is closely related to local wind forcing and sea level variability. A vector regression to buoy winds demonstrates that the ocean response is highly anisotropic, with the magnitude and veering of the surface current strongly dependent on the direction of the wind. Comparisons with the CIOPS-W model currents show reasonable agreement with the HF radar currents, particularly with respect to the along-strait transport.

Development of Experimental Bench for Wireless Power Transfer

Wireless-power-transfer (WPT) for powering low-power devices has increased in recent years. The inductive resonant coupling method is the most used technique for this application and consists of taking advantage of the magnetic field generated in a coil so that there is current circulation in another nearby coil. In this work, using this technique, the series-series (SS) compensation topology was used to develop a test bench that should supply a load of up to 10W. Therefore, a brief explanation of the topic, calculations used, defined parameters, and we presented preliminary results of the proposed system.

When and which patients should receive remdesivir?

When and which patients should receive remdesivir?

Occurrence Of Tar Pollution Along Some Shores In Indonesia

Four typicul Indonesian costr : Jakarta Bay, Malacea and Makussar Strats, as well as South coart of Yogyakurta, Central Java, were nurveyed in August 1982 and May 1984 with the purpose of assessing, quantifying and identifying tar stranded thereon. The estimution of tar pollution was determined using a typical statistical methodology bated on a stratifled rundom sampling Quantitative beach sampling conducted in Augar 1982 during the East monuoon season yielded avenage stranded beach tar concentrations nanging from less than 1 gim to about 2.800gim (values in grost weight) of shoreline. The vuhuer obtutned in May 1984 after the West monsoon ranged between 2,8 and 9.500 g/m. In the two nunveys, the most polhuted area was located in the Kepulaun Seribu area (Jaharta Ray) Average tar weight of over 2 kaim beach are comparuble to that of other couut along major tanker routes as Kuwait or Benmuda Obuerved tur pollution in Aulae Kapal Besar , labon Kecil, Nirup, Pelampong and Takong Kecl (in the Straits of Malacca) and Langga Beach (on the Straits of Makussar) war lower during these nurveys. The reason why inapite of such dense marine traffic is not clear, until one examines the internal current circulation between the islands, the local geopaphical feutwes of the site and preferen tial wind directions.

Josephson-like Oscillations in Toroidal Spinor Bose–Einstein Condensates: A Prospective Symmetry Probe

Josephson junctions are essential ingredients in the superconducting circuits used in many existing quantum technologies. Additionally, ultracold atomic quantum gases have also become essential platforms to study superfluidity. Here, we explore the analogy between superconductivity and superfluidity to present an intriguing effect caused by a thin finite barrier in a quasi-one-dimensional toroidal spinor Bose–Einstein condensate (BEC). In this system, the atomic current density flowing through the edges of the barrier oscillates, such as the electrical current through a Josephson junction in a superconductor, but in our case, there is no current circulation through the barrier. We also show how the nontrivial broken-symmetry states of spinor BECs change the structure of this Josephson-like current, creating the possibility to probe the spinor symmetry, solely using measurements of this superfluid current.

Aharonov-Bohm oscillations in phosphorene quantum rings: Mass anisotropy compensation by confinement potential

We consider the Aharonov-Bohm (AB) effect on a confined electron ground state in a quantum ring defined electrostatically within the phosphorene monolayer. The strong anisotropy of effective masses in phosphorene quenches ground-state oscillations for a circular ring because of interrupted persistent current circulation around the ring. An elliptic deformation of the confinement potential can compensate for the anisotropy of the effective masses and produce ground-state parity transformations with the AB periodicity. Moreover, a specific ratio of the semiaxes is determined for which the spectrum becomes identical to that of a circular quantum ring and an isotropic effective mass. We identify a generalized angular momentum operator which commutes with the continuum Hamiltonian for the chosen ratio of the semiaxes that closes the avoided crossings of energy levels for states of the same parity and spin. Ground-state oscillations for the two-electron ground state are also discussed.

Mitigation of Interturn Short-Circuits in IPMSM by Using MTPCC Control Adaptive to Fault Severity

Incipient interturn short-circuits (ITSCs) in permanent-magnet synchronous machines (PMSMs) develop to direct short-circuit without proper mitigation. This article proposes an ITSC mitigation control for standard three-phase interior PMSMs (IPMSMs) driven by typical three-phase inverters, named as maximum torque per circulating current (MTPCC), to constrain the circulating current (CC) due to ITSC within acceptable limits so as to delay the insulation degradation between shorted turns, and to maximize output torque to support the postfault performance. In the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> current plane, it is shown that for a specific fault severity and machine speed, the operating points with the same CC form a circle, and for constant torque with ITSC is a hyperbola. ITSC is a fast-developing fault that implies the fault severity continues to increase with time, and the positions of the CC circle and torque hyperbola change with the increasing fault severity in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> current plane. The MTPCC control updates the mitigation operating point automatically, depending on the positions of the CC circle and torque hyperbola with respect to the circle of the machine's maximum current, to produce the maximum possible torque as the fault severity changes, which shows that it is adaptive to the variation of fault severity. The proposed mitigation control is validated through experiments.

Thermal response of active Si in press-fit rectifier diodes by confocal Raman microscopy: Influence of diode design and technology

Overheating resulting from the circulation of high electric currents (in the order of tens of amperes) that some electronic devices undergo when they are in operation, can induce structural modifications such as mechanical stresses that could reduce their lifetime. In order to optimize their performance, understanding the phenomenology that takes place in devices at high-temperature regimen induced under operating conditions is fundamental. In this work, the thermal behavior of the Si-based semiconductor part of several press-fit rectifier diodes with different design and technology (Schottky, Metal Oxide Semiconductor and PN junction) has been studied by Confocal Raman Microscopy. The experiments have been performed on two specific functional parts of the active Si chip (i.e., near and far from the Si/electrode interface), discerning non-thermal effects such as stress and doping from the purely thermal ones with a specific analysis procedure of the Si T2g Raman active mode. This methodology enables an advance, non-destructive and located characterization of the thermal response of the diodes, which will help to optimize the performance of electronic devices and extend their useful life and reliability by avoiding or, at least, minimizing the damage caused by the temperature excess.

Spatial and Vertical Benthic Foraminifera Diversity in the Oxygen Minimum Zone of Mejillones Bay, Northern Chile

Mejillones Bay is located in northern Chile (23°S) and is influenced by an Oxygen Minimum Zone (OMZ), with oxygen levels below 0.5 ml l–1. This area presents particular ecological characteristics, such as circulation of currents, hotspot, high productivity and industrial activity. This extreme ecosystem generates the need to understand their dynamics and changes across time and space, as well as to identify the main differences with other OMZs. For this reason, we studied the benthic foraminifera to use them as environmental and oxygenation proxies. For this purpose, two sediment cores (ZA and Z1A) were collected, obtaining 14 samples of the first 8 cm (vertical distribution), and 18 samples with a mini boxcore (spatial distribution). When analyzing the foraminifera community, some similarities were found in environmental characteristics of other OMZs, such as the predominance of Bolivina seminuda, Bolivina costata, Epistominella exigua, Fursenkoina sp., and Nonioella stella (species typical of hypoxic conditions). In addition, a high abundance of angular-asymmetric morphologies was observed, indicating eutrophied silty substrates and low current circulation. However, the Mejillones Bay recorded a particular spatial and vertical dynamics respect to others OMZs, due to presence of other species of Bolivinids not reported for this area before, and a high abundance of Buliminella elegantissima, which is not recorded in most of OMZs. Foraminifera with rounded-symmetric morphologies were present and dominant in deeper layers, reflecting a turbulent and high-energy environment. On the basis of depth and conditions of microxia or dysoxia, no significative pattern of spatial and vertical distribution was observed. The latter can be explained by local factors such as cyclonic and anticyclonic whirlpools, wastewater from industrial activity and natural disaster such a Tsunami occurred in 1877. These factors contributed to the mixture of the benthic foraminifera and prevented the formation of spatial and vertical patterns. Finally, an intensification of hypoxia was identified, indicating microxia (0,01 ml l–1) in the superficial layers (0–3 cm from years 1996 to 2012), while the deeper layers (4–8 cm from years 1985 to 1877) presented foraminiferal species that indicated dysoxia conditions (0,07 ml l–1). The latter differs from other OMZs, which show greater oxygenation in the most superficial layers and microxia in deeper layers. This study represents the first ecological reconstruction using benthic foraminifera proxies for the Mejillones Bay, which results indicate an OMZ with ecological and environmental features that differ from other OMZs.

Improved Prediction of Hydrologic Properties of Heterogeneous Porous Media at Pore-Scale - a Multi-physics Lattice Boltzmann Study

Predicting and analyzing the dynamic and reactive behavior of confined fluids at the pore scale, especially in heterogeneous porous media with multi-physics phenomena, is one of the vital challenges in the energy industry and has found great interest among researchers in various fields. In this paper, various physics of the Lattice Boltzmann method, including hydrodynamics, advection–diffusion, and reaction, are combined with a geometry evolution algorithm to model the alteration of dead-end pore structure under reactive circulation currents, which in turn play a significant role in predicting the permeability of the porous medium. Detailed interpretation of the results of sensitivity analysis concerning geometric properties showed that under certain conditions, a rotational flow (i.e., circulation current) is formed in the dead-end pore that increases the rate of mass transfer into the cavity, leading to more mineral precipitation. It turned out that the formation of rotational currents resulting from the geometry evolution in vuggy and dead-end cavity leads to a higher power in the power-law relationship. These results are a fundamental step in understanding and developing a new generation of predictive porosity–permeability relationships (i.e., clogging models) during mineral precipitation, which have so far been largely based on empirical relationships.

Analytical Methodology for Modelling of Circulating Current Loss in Synchronous Electrical Machines With Permanent Magnets

This paper describes a novel analytical methodology for modelling winding copper losses as a result of circulating currents (CC) in permanent magnet synchronous machines (PMSM). CCs are important to be considered at an early design stage especially in high frequency and high performance machines where sub-optimal design choices can lead to significant alternating current (AC) losses. Nowadays mainly FEM method is used for precise calculation of circulating currents. However, it suffers on significant computational time required for building models and simulation of circulating current effect that makes it inapplicable for optimization purpose. The paper demonstrates the computationally efficient methodology through comparison with FEM based models for high power density PMSM with concentrated winding and validation against experimental results for a stator section at the fundamental frequency from 500 Hz to 2000 Hz. The methodology allows simulation of CC and AC Ohmic losses when machine supplied by any current waveforms, for arbitrary size and location of the conductors in the slots. A key novelty of the proposed method is the utilization of subdomain (SDM) approach in conjunction with solution of a system of ordinary differential equations (ODE) for an equivalent electrical circuit of machine windings. This approach is precise and fast but has never been used before for circulating current loss evaluation in windings of electrical machines. The model is intended to be used at the design stage of an electrical machine where multiple geometric dimensions, winding configurations and conductor placement in the slot are considered towards an optimal design.

A Five-Level Torque Controller Based DTC Scheme for Open-End Winding Five-Phase IM Drives With Single DC Source and Auxiliary Plane Harmonic Elimination

This article presents a new five-level torque hysteresis based direct torque control scheme for dual inverter fed five-phase induction motor drives with open-end stator windings. Three voltage levels required to implement the five-level torque hysteresis controller are generated by combining the appropriate voltage vectors of the two inverters. The proposed scheme ensures that the harmonic voltages in the nontorque producing auxiliary plane are nullified in every switching period. Since the switching voltage vectors are realized using adjacent and nonadjacent line voltages, the magnitude of the voltage appearing across the windings is much higher compared to the conventional star connected five-phase drive, for the same dc link voltage. This feature reduces the dc link voltage requirement substantially for a given motor voltage. The switching scheme employed prevents circulation of common mode currents even when a common dc source is used for feeding both inverters. The proposed scheme is experimentally verified on a five-phase induction motor drive with open end stator windings. The control scheme is implemented using TMS320F28335 digital signal controller.

Modelling the influence of Tidal Energy Converters on sediment dynamics in Banks Strait, Tasmania

As the tidal energy industry grows, developers are interested in the influence that large scale arrays might have on their surrounding environment including hydrodynamic and sediment. Understanding of local and regional sediment dynamics is an important element for environment impact and site assessments, as changes in sediment processes could alter bed ecosystems. In Australia, the Banks Strait located in the Northeast of Tasmania has been identified as a promising site for tidal energy. Very large sand waves have been observed near the area suitable for tidal turbines installation and they may interfere with human activities. Building from previous work, a 2D regional scale model investigated the influence of different tidal farms on the morphology of Banks Strait and especially the sand waves. Results showed that tidal farm of more than 49 MW rated power will alter the circulation of residual currents in Banks Strait leading to significant changes in the sediment dynamics, and farms less than 24.5 MW will have negligible influence on the migration of sand waves.

Quantum theory of photonic vortices and quantum statistics of twisted photons

The topological charge of a photonic vortex is an essential quantity in singular optics and the critical parameter to characterize the vorticity of twisted light. However, the definition of the photonic topological charge remains elusive. Here we put forth a theoretical formalism to provide a comprehensive treatment of photonic vortices. We introduce quantum operators for the photon current density and helicity current density based on the continuity equations from the paraxial Helmholtz equation. Our formalism allows us to introduce flow velocity and circulation for photonic currents in parallel to their counterparts in superfluids. The quantized circulation of the photonic currents is conserved during propagation and it gives an explicit definition of the photonic topological charge as the winding number of a photonic vortex. In particular, we predict helicity current generated pure-helicity vortices, in which the photon current vanishes. Finally, we show an interesting effect that the quantum statistics of twisted photon pairs are essentially determined by their spin states.

Hydrogeological and hydrochemical framework of the distal section of the Salado-Juramento fluvial megafan (Bajos Submeridionales) in South America

The Bajos Submeridionales (BBSS) (Argentina) is a 54,800 km2 hydrological system located at the distal part of the Salado-Juramento Fluvial Megafan (SJRM). Its climate evolves from humid-subtropical in the east to semiarid in the west. Its hydrogeological system is typical of extensive plains, topography locally imposes vertical flows and neotectonic elements define system boundaries and drains. These characteristics and poor data availability represent a major challenge for identifying a hierarchical subsurface flow system and the influence of neotectonics. This work characterizes the hydrogeology of the BBSS and proposes a conceptual model based on integrated systematic information including 453 water level, 145 hydrochemical, and 99 δ18O- δD data. Four hydrogeological units are identified (HU1–HU4), two of which are divided into sub-units based on their sedimentary sequence. The main chemical types are Na-Cl, Na-Cl/SO4, Na-HCO3/Cl, Na-Cl/HCO3, and HCO3-Na. Dominant ions are Na, Cl, and SO4. Measured electrical conductivity reaches values as high as 132,000 μS/cm. Water chemistry modifying processes include halite, gypsum, and carbonate dissolution; ion exchange; inter-HU water mixing; and evapo-concentration. δ18O-δD and EC-δ18O suggest the existence of subsurface flow sectors. In the south, shallow and medium depth groundwater flows respond to the current circulation of the SJRM. Recharge occurs in the sub-Andean Ranges and point discharges, at the western lakes and some lakes of the Golondrina-Calchaquí system. Precipitation recharges shallow flows locally in the north, center, and east. Extreme west HU2 and HU1 receive deep upward thermal flows through structural lineaments. Thus, the Otumpa Hills morpho-structure would be a barrier to shallow HU1 flow, though not to deep regional HU2 and HU4 flows. Regional groundwater flow is from NW to SE and both local and regional flows would discharge in the Paraná River. The new conceptual model developed helps to further understand the groundwater system of a large plain in South America.

Silurian conodonts from the Nyalam region, southern Xizang (Tibet), China, and their biostratigraphical and palaeobiogeographical implications

The Silurian conodont biozonation has been well established in many areas of the world, but not yet in China. The Nyalam region of southern Xizang (Tibet) is one of the best locations for studying Silurian conodonts in China. In this paper, we establish five conodont biozonal units from the Pulu Formation: the Ozarkodina sagitta sagitta Biozone, the Kockelella crassa Biozone, the Kockelella variabilis variabilis – Ancoradella ploeckensis Zonal Group, the Polygnathoides siluricus Biozone, and the “ Ozarkodina ” eosteinhornensis s.l. interval Biozone. We assign the Pulu Formation to the Llandovery (upper Telychian) to Pridoli stages based on the conodonts as well as the graptolites from underlying strata. The Silurian conodont species in the Nyalam region are widely distributed in the strata from the Laurussia and Gondwana, which indicates the cosmopolitan characteristic of the conodont fauna from the Wenlock to Pridoli epochs was caused by the circulation of ocean currents. • Five conodont biozonal units from Wenlock to Pridoli were identified in the Nyalam region. • Pulu Formation in the Nyalam region is Telychian to Pridoli in age. • Silurian conodont fauna in the Nyalam region have a cosmopolitan characteristic.

A comprehensive review of the circulation of microplastics in aquatic ecosystem using scientometric method.

Nowadays, the extensive application of microplastics (MPs) has led to the gradual accumulation of toxicity in aquatic environment and caused potential harm to aquatic organisms and human life, which has become a hot issue of worldwide concern. Although MPs show inert or sublethal toxicity in many cases, its long-term existence can still cause harmful ecological effects. However, to our knowledge, there is a lack of comprehensive literature on the current research hotspots, circulation process, and future development trend of MPs in aquatic ecosystem. This study aims to comprehend the current research hotspots and future development trend in the field of the MPs in aquatic ecosystem using scientometric method. And the circulation process of MPs in aquatic ecosystem is also investigated. The results indicate the most of the current publications on MPs in aquatic ecosystems focus on the formation and harmful properties of MPs. The current research hotspots mainly include the causes of the formation of MPs, the extent of contamination, deposition phenomena, and the toxicity and harm caused to aquatic organisms and humans after ingestion. And the future trends in the researches related to MPs mainly include the study of microplastic cycling processes in aquatic and terrestrial ecosystems, as well as the effective collection of microplastics and their conversion into valuable carbon sources. This review has filled in the knowledge gap in the field of MPs research in aquatic ecosystem to some extent and plays a guiding role in the future researches.

Study on optimization of laying mode of two parallel high voltage cables in the same phase of two circuits

In power lines, the proportion of parallel cables is gradually increasing, but the uneven current distribution and sheath circulation affect the safe and stable operation of parallel cables. Existing studies show that cable current and sheath circulation are obviously affected by cable laying mode. At present, the designed cable laying mode is as “pin” laying and horizontal “I” laying. Combined with the above engineering difficulties, this paper focuses on the parameter optimization scheme of 220 kV two circuit parallel cables in the same direction when the metal sheath is cross connected and grounded. Firstly, the operation model of 220kV two circuits in-phase two parallel cables is established. The numerical differences between the current distribution non-uniformity coefficient and sheath circulating current of the cables are analyzed and calculated under the condition of “pin” laying and horizontal “I” laying. Meanwhile, the influence of different phase sequence arrangement on the current distribution non-uniformity coefficient and sheath circulating current of the cables is compared. Secondly, the cable laying mode of “symmetrical pin” is designed, and the improvement effect of uneven coefficient of cable current distribution and metal sheath circulating current under “symmetrical pin” laying is compared and analyzed. Finally, the differences of the above parameters in different phase sequence arrangements are compared and analyzed. The research results show that the symmetrical pin laying can improve the uneven distribution of current and sheath circulating current, which has important engineering practical value.

The currents, sea surface temperature, and salinity patterns in the Bay of Bengal

The Bay of Bengal is a semi-enclosed basin, with its southern side open to the Indian Ocean. Therefore, the current circulation is very influential in the condition of the ocean parameters. This study aims to examine the effect of current velocity on the distribution pattern of sea surface temperature (SST) and sea surface salinity (SSS) in February and August in 2017 in the Bay of Bengal. This study uses the results of Hybrid Coordinate Ocean Model (HYCOM) data for the main parameters, namely current, temperature and salinity which were analyzed with the calculation results of precipitation and evaporation data. The results of the data obtained in February showed the average current velocity conditions and low SST and relatively high SSS in the south. In August the average current velocity and SST is high and SSS is low. The results of the average data of low rainfall and relatively low evaporation are produced in February, the results of the average high rainfall and relatively high evaporation are produced in August. The resulting value gives the results of the relationship between current circulation and changes in parameter conditions in the waters.