Snowflake Research Articles

Ultrasound emulsification of supercritical extracts of biquinho pepper (Capsicum chinense)

Capsinoids, recently indentified in Biquinho peppers (BP), presents several biological activities, as prevention of tumorigenesis and increase of energy expenditure. In order to verify if the emulsification process could increase the bioactivity of the supercritical fluid (SFE) extracts from BP, emulsified systems were produced by ultrasound emulsification process using Hi-Cap and Snow flakes as emulsifers. The results indicate that the Snow flakes was more effective in producing small particles, as well as higher emulsification time and power (6 min and 720 W). It was not observed an increase in biological activity of the extract with the emulsification process.

The effect of the secondary x-point on the scrape-off layer transport in the TCV snowflake minus divertor

The snowflake (SF) magnetic configuration is investigated as a potential power exhaust solution for a fusion reactor, but also to improve our understanding of divertor physics in general. Unlike a conventional single null (SN), it features an additional nearby x-point, which deeply modifies the magnetic field in the scrape-off layer (SOL) and can thereby affect parallel and cross-field transport of heat and particles. This paper investigates the power exhaust properties of the snowflake minus (SF-) configuration on the TCV tokamak, for Ohmically heated, L-mode, low-density, attached plasmas for a range of x-point separations, magnetic field directions and locations of the secondary x-point (low-field-side (LFS) or high-field-side (HFS)). Due to the relatively large x-point separation in physical space, this study probes x-point transport features in general, rather than reactor relevant aspects of the SF configuration. The target heat fluxes at all strike points are simultaneously monitored with an infrared (IR) thermography system and the kinetic profiles of the SOL at the outer mid-plane with a reciprocating probe (RCP). The placement of the additional x-point is seen to affect the inner-outer divertor power balance. An effective heat flux width for the SOL in the low poloidal field region is inferred from the measured power repartition between the two SOL manifolds created by the secondary x-point. For the LFS SF- configuration (secondary null in the LFS SOL), the is two times larger than that measured by the RCP at the outer mid-plane and by IR at the outer target of a comparable SN, while the outer mid-plane SOL profiles are similar to the SN. This is interpreted as the effect of increased effective cross-field diffusivity in the intra-null region relative to the rest of the SOL. For the HFS SF- configuration (secondary null in the HFS SOL), no such increased transport is observed. The pressure-driven plasma convection expected near the primary null cannot explain the increased , which is instead consistent with interchange ballooning-like turbulence enhanced by the low poloidal field.

Controllable growth of MoS2 nanosheets on novel Cu2S snowflakes with high photocatalytic activity

Herein, we, for the first time, report the controllable syntheses of the snowflake-like Cu2S architectures by using a template free, facile hydrothermal route, in which thiourea as the precursor of sulfur and EDA as the solvent. It is surprising that the Cu2S snowflakes show a higher photocatalytic activity than the other samples (Cu2S dendrites and sheets), has been mainly ascribed to its high light absorbance and BET area. Then the MoS2 nanosheets (NSs) are uniformly distributed on the Cu2S snowflake (SF) substrate, the obtained MoS2 NS/Cu2S SF composite manifests high specific surface area (60.512 m2 g−1) and large pore volume (0.148 cm3 g−1), which are favorable for the efficient light capturing together with the rapid transfer of charge carriers. In comparison with the pure Cu2S, the MoS2 NS/Cu2S SF composite exhibits much enhanced activity and long-term stability towards the photocatalytic degradation of organic dye pollutants and hydrogen production. The improved photocatalytic activity could be owed to two aspects, namely the enhanced light trapping and scattering ability benefited from large specific area of unique snowflake-like structural features and improved charge separation activity of heterojunction between MoS2 and Cu2S.

Plasma simulation of complex HL‐2M divertor geometries using SOLEDGE2D‐EIRENE edge plasma transport code

In this paper, we present the initial results of a fundamental study of the impact of the magnetic configuration on the detachment behaviour and heat exhaust in HL‐2M simulation for low power.Starting from typical HL‐2M single‐null shapes, the plasma density at the core–edge interface is varied from 1 × 1019 to 8 × 1019 m−3 to investigate the detachment plasma characteristics. The additional X‐point near the primary X‐point and target is invested in snow flake plus (SF+) and snow flake minus (SF−) configurations. Detachment at the outer target is also studied in these simulations. The degree of detachment and the radiation location are investigated using the SOLEDGE2D simulation results. It is found that advanced divertor configurations result in a deeper detachment under the same plasma density and in a reduction in the detachment threshold.

Developing physics basis for the snowflake divertor in the DIII-D tokamak

Recent DIII-D results demonstrate that the snowflake (SF) divertor geometry (see standard divertor) enables significant manipulation of divertor heat transport for heat spreading and reduction in attached and radiative divertor regimes, between and during edge localized modes (ELMs), while maintaining good H-mode confinement. Snowflake divertor configurations have been realized in the DIII-D tokamak for several seconds in H-mode discharges with heating power –5 MW and a range of plasma currents MA. In this work, inter-ELM transport and radiative SF divertor properties are studied. Significant impact of geometric properties on SOL and divertor plasma parameters, including increased poloidal magnetic flux expansion, divertor magnetic field line length and divertor volume, is confirmed. In the SF-minus configuration, heat deposition is affected by the geometry, and peak divertor heat fluxes are significantly reduced. In the SF-plus and near-exact SF configurations, divertor peak heat flux reduction and outer strike point heat flux profile broadening are observed. Inter-ELM sharing of power and particle fluxes between the main and additional snowflake divertor strike points has been demonstrated. The additional strike points typically receive up to 10–15% of total outer divertor power. Measurements of electron pressure and poloidal beta support the theoretically proposed churning mode that is driven by toroidal curvature and vertical pressure gradient in the weak poloidal field region. A comparison of the 4–4.5 MW NBI-heated H-mode plasmas with radiative SF divertor and the standard radiative divertor (both induced with additional gas puffing) shows a nearly complete power detachment and broader divertor radiated power distribution in the SF, as compared to a partial detachment and peaked localized radiation in the standard divertor. However, insignificant difference in the detachment onset w.r.t. density between the SF and the standard divertor was found. The results complement the initial SF divertor studies conducted in high-power H-mode discharges in the NSTX and DIII-D tokamaks, and, along with snowflake divertor results from TCV and other tokamaks, contribute to the physics basis of the SF divertor as a power exhaust concept for future high power density tokamaks.

Design of snowflake-diverted equilibria of CFETR

The Chinese Fusion Engineering Test Reactor (CFETR) represents the next generation of full superconducting fusion reactors in China. Recently, CFETR was redesigned with a larger size and will be operated in two phases. To reduce the heat flux on the target plate, a snowflake (SF) divertor configuration is proposed. In this paper we show that by adding two dedicated poloidal field (PF) coils, the SF configuration can be achieved in both phases. The equilibria were calculated by TEQ code for a range of self-inductances li3. The coil currents were calculated at some fiducial points in the flattop phase. The results indicate that the PF coil system has the ability to maintain a long flattop phase in 7.5 and 10 MA inductive scenarios for the single null divertor (SND) and SF divertor configurations. The properties of the SF configuration were also analyzed. The connection length and flux expansion of the SF divertor were both increased significantly over the SND.

Petrogenesis and Geochemical Properties of Dome-shaped Subvolcanic Complexes in Southwest of Shahrab (Northeast of Isfahan)

<p>The studied area is located in southwest of Shahrab village near Ardestan city. This zone is part of Uremia- Dokhtar magmatic belt. Outcrops composed of rhyolite and rhyodacite dome-shaped volcanic complexes are scattered in the studied area; some of which are exploited as ornamental stone. The main rhyolite minerals include quartz, plagioclase and alkali feldspar. Minor minerals include Apatite, Sphene and opaque minerals and of the secondary minerals in these rocks Christie, Chlorite, Epidote and calcite could be mentioned. Calcite exists in rocks in form of filler of micro-fissures. The ignimbrite presence in this group of rocks in form of xenolith is one of the features of this rock group. The main primary texture in rhyolite and rhyodacite is porphyritic and the secondary texture includes pull-apart, snow flake and spherulitic textures. Geochemical evidences indicate that these rocks are sub-alkaline, Calc-alkaline compositions with high potassium and meta-alumina. These rocks have negative EU anomaly that is the feature of acidic igneous rocks. The studied rocks show high enrichment of LREE and LILE elements. The primary magmas constituting these rocks have mantel origin raised under extreme compressional conditions on continental crust in a tectonic environment of volcanic arc. It seems that these rocks are formed in connection with continuance of volcanic activities associated with subduction of Neolithic oceanic plate beneath continental plate of Iran. </p>

Surviving the Winter Blues … and the Flu!

Fall has finally arrived after a very hot and dry summer here in Northern California. Many of you across the country undoubtedly read news reports about the devastating wildfires that have affected California, Washington, and Montana, as well as many other western states. Couple those disasters with the very active and destructive hurricane season experienced by residents of our southern states, and I think we would all agree that winter cannot arrive soon enough!As the leaves change and the first flakes of snow begin to fall, this time of year reminds us how much we depend on the services of pharmacists — not only to help us stave off seasonal flus, but to prevent the winter blues. Fortunately, technological advances are making those services more effective and easier to obtain … and to provide.Indeed, technology continues to evolve at a pace that is truly remarkable, and to touch every aspect of our lives, including our health care. In this edition of JCPhP, author Dr. Jason Lam reviews some of the pharmacy-based smartphone apps that are available today to assist patients and consumers with everything from reminding us to refill our prescriptions and helping us find a pharmacy to understanding the possible side effects of (and interactions between) the medications we take. Not only do these apps empower patients by providing a host of self-management tools, but they also enable pharmacists to extend their reach beyond the physical pharmacy or hospital to help patients who need more assistance managing their medications at home. By serving as important clinician “extenders,” these apps can help patients feel more secure and more connected to their health care providers — and because they offer easy and immediate access to information, the apps can ameliorate the isolated feeling that some patients (particularly those who are homebound or underserved) can experience when they are home alone, trying to manage their medications on their own.One of the many useful features such smartphone apps typically offer is a pharmacy locator for such services as immunizations. As pharmacists prepare to ramp up and deliver these services in fall and winter, they will be pleased to read Dr. Keri Hurley-Kim's update on the immunization recommendations by the Advisory Committee on Immunization Practices (ACIP) at the Centers for Disease Control and Prevention. In particular, Dr. Hurley-Kim discusses the latest influenza; human papilloma virus (HPV); meningococcal serogroups A, C, Y, W-135; meningococcal serogroup B; cholera; and yellow fever. These updates are timely and important for clinicians who are preparing to meet the preventive health care needs of the public as diseases like the flu begin their traditional seasonal ramp-up.We hope you enjoy all the manuscripts in this edition of JCPhP, and we look forward to featuring many more contemporary practice features in coming editions. Wishing each of you a wonderful holiday season, filled with health and well-being!Warm regards,Jon R. Roth, MS, CAEExecutive Editor

Features in air ions measured by an air ion spectrometer (AIS) at Dome C

Abstract. An air ion spectrometer (AIS) was deployed for the first time at the Concordia station at Dome C (75°06′ S, 123°23′ E; 3220 m a. s. l. ), Antarctica during the period 22 December 2010–16 November 2011 for measuring the number size distribution of air ions. In this work, we present results obtained from this air ion data set together with aerosol particle and meteorological data. The main processes that modify the number size distribution of air ions during the measurement period at this high-altitude site included new particle formation (NPF, observed on 85 days), wind-induced ion formation (observed on 36 days), and ion production and loss associated with cloud/fog formation (observed on 2 days). For the subset of days when none of these processes seemed to operate, the concentrations of cluster ions (0.9–1.9 nm) exhibited a clear seasonality, with high concentrations in the warm months and low concentrations in the cold. Compared to event-free days, days with NPF were observed with higher cluster ion concentrations. A number of NPF events were observed with restricted growth below 10 nm, which were termed as suppressed NPF. There was another distinct feature, namely a simultaneous presence of two or three separate NPF and subsequent growth events, which were named as multi-mode NPF events. Growth rates (GRs) were determined using two methods: the appearance time method and the mode fitting method. The former method seemed to have advantages in characterizing NPF events with a fast GR, whereas the latter method is more suitable when the GR was slow. The formation rate of 2 nm positive ions (J2+) was calculated for all the NPF events for which a GR in the 2–3 nm size range could be determined. On average, J2+ was about 0.014 cm−3 s−1. The ion production in relation to cloud/fog formation in the size range of 8–42 nm seemed to be a unique feature at Dome C, which has not been reported elsewhere. These ions may, however, either be multiply charged particles but detected as singly charged in the AIS, or be produced inside the instrument, due to the breakage of cloud condensation nuclei (CCN), possibly related to the instrumental behaviour under the extremely cold condition. For the wind-induced ion formation, our observations suggest that the ions originated more likely from atmospheric nucleation of vapours released from the snow than from mechanical charging of shattered snow flakes and ice crystals.

How snowflakes grow

How snowflakes grow

Snowflake slur is offensive

Snowflake slur is offensive

CFETR equilibrium with self-consistent pedestal structure

The Chinese Fusion Engineering Test Reactor (CFETR), which aims to fill the gaps between the International Thermonuclear Experimental Reactor (ITER) and DEMO, is in the design stages. Plasma equilibrium is an important basis for tokamak plasma research. We present a method for constructing CFETR equilibria with a self-consistent pedestal structure, using an EPED-like model and the Sauter bootstrap current model. With this method, the pedestal structures of the snowflake (SF) divertor configuration for CFETR are calculated as well. It is shown that the pedestal heights and widths of SF+ and SF- are slightly larger than those in the standard divertor configuration.

Formation of snowflake diverted equilibria of CFETR

The Chinese Fusion Engineering Test Reactor (CFETR), a next-generation fully superconducting fusion reactor, is in the design stages. In this paper, we present three snowflake (SF) divertor configurations (SF+, exact SF, SF−), to demonstrate the possibility of attaining these SF configurations with two special additional poloidal-field (PF) coils set on the CFETR, where all PF coils are outside the TF coils. Starting from a single null divertor (SND), a sequence of desirable SF configurations can be realized whereby the PF-coil currents are below the maximal design limits. Compared to the SND, the potential properties of these SFDs, including low-poloidal-field area, flux expansion, connection length, are analyzed and presented in this paper. As the required currents in some PF coils are higher for a SFD than a SND, an operating space of coil currents for the SFD was calculated at a range of the internal inductance (li) and flux states. The result indicates that though the current in CS1 PF coil limits access to the lower li and flux state region, the PF coils system can provide ∼30Wb for the flattop phase.

M3D-C1 simulations of the plasma response to RMPs in NSTX-U single-null and snowflake divertor configurations

In this work, single- and two-fluid resistive magnetohydrodynamic calculations of the plasma response to magnetic perturbations in single-null (SN) and snowflake (SF) divertor configurations are compared with those based on the vacuum approach. The calculations are performed using the code M3D-C1 and are based on simulated NSTX-U plasmas. Significantly different plasma responses were found from these calculations, with the difference between the single- and two-fluid plasma responses being caused mainly by the different screening mechanism intrinsic to each of these models. Although different plasma responses were obtained from these different plasma models, no significant difference between the SN and SF plasma responses were found. However, due to their different equilibrium properties, magnetic perturbations cause the SF configuration to develop additional and longer magnetic lobes in the null-point region than the SN, regardless of the plasma model used. The intersection of these longer and additional lobes with the divertor plates are expected to cause more striations in the particle and heat flux target profiles. In addition, the results indicate that the size of the magnetic lobes, in both single-null and snowflake configurations, are more sensitive to resonant magnetic perturbations than to non-resonant magnetic perturbations.

Effects of the second X-point on hot VDE in HL-2M

Study of the hot-plasma vertical displacement event (VDE) in advanced divertor configurations is of significant importance for ITER and for future fusion reactors. The newly designed, medium-sized copper-conductor machine HL-2M has the capability of generating the second X-point for various advanced divertor configurations. In this paper, effects of the second X-point on the hot VDE in HL-2M are numerically investigated by utilizing the non-linear time-dependent DINA code. The simulation results show that the existence of the second X-point at certain special locations appears to have a better stability in the vertical direction, compared to the standard configuration with the same main plasma parameters. Meanwhile, the peak halo current during the current quench tends to increase as the second X-point changes in the horizontal direction. The same quantity decreases as the second X-point changes in the vertical direction away from the dominant X-point. From the view point of minimizing the halo current, the tripod is better than the standard configuration, followed by the snowflake-plus and the exact snowflake (SF) configuration. The SF-minus is the worst scenario. On the other hand, the tripod configuration, as well as the SF minus configurations, results in relatively higher peak electromagnetic force acting on the vacuum vessel, when compared to other aforementioned configurations.

Proposal of an alternative upper divertor in ASDEX Upgrade supported by EMC3-EIRENE simulations

We discuss the benefits of installing a pair of in-vessel coils with currents |Ifx| ≲ 50 kAt in the upper divertor of ASDEX Upgrade (AUG) to study a series of ‘alternative’ divertor configurations, like the Snowflake (SF) and the X-divertor (XD), that are currently considered as alternative solutions for the power exhaust problem. The possibility of operating the standard lower single-null (SN) and double-null (DN) would be preserved. Potential effects to reduce the peak parallel- and/or perpendicular heat flux are predicted from a simple geometrical-diffusive model as well as by numerical EMC3-EIRENE simulations for pure deuterium attached conditions with spatially constant diffusion coefficients. Beyond that a series of other potential transport- and radiation related heat flux mitigation effects are identified and could be studied experimentally with the modified upper divertor in the high-power divertor Tokamak AUG.

‘Instead of fetching flowers, the youths brought in flakes of snow’: exploring extreme weather history through English parish registers

Parish registers provide organized, dated and located population data and as such, are routinely among the most frequently consulted documents within the holdings of county record offices and archives. Throughout history, extreme weather has had significant impacts on the church, its congregation, and local landscape. It is for these reasons that extreme weather events have been deemed worthy of official note by authors of many registers. Although isolated entries have been used as supporting evidence for the occurrence of a number of historic extreme weather events, the information that parish registers contain relating to weather history has not been studied in its own right. Parish register narratives add new events to existing chronologies of extreme weather events and contribute to our understanding of their impacts at the local level. As public and well used documents they also function to keep the memory of particular events alive. The examples in this paper cover a wide range of weather types, places, and time periods, also enabling recording practice to be explored. Finally, as the number of digitized registers increases, we highlight the risks of weather narratives being obscured, and reflect on how the weather history contained within might be systematically captured.

Snowflake Divertor Experiments in the DIII-D, NSTX, and NSTX-U Tokamaks Aimed at the Development of the Divertor Power Exhaust Solution

Experimental results from the National Spherical Torus Experiment (NSTX), a medium-size spherical tokamak with a compact divertor, and DIII-D, a large conventional aspect ratio tokamak, demonstrate that the snowflake (SF) divertor configuration may provide a promising solution for mitigating divertor heat loads and target plate erosion compatible with core H-mode confinement in the future fusion devices, where the standard radiative divertor solution may be inadequate. In NSTX, where the initial high-power SF experiment was performed, the SF divertor was compatible with H-mode confinement, and led to the destabilization of large Edge Localized Modes (ELMs). However, a stable partial detachment of the outer strike point was also achieved where inter-ELM peak heat flux was reduced by factors 3–5, and peak ELM heat flux was reduced by up to 80% (see standard divertor). The DIII-D studies show the SF divertor enables significant power spreading in attached and radiative divertor conditions. Results include: compatibility with the core and pedestal, peak inter-ELM divertor heat flux reduction due to geometry at lower $n_{e}$ , and ELM energy and divertor peak heat flux reduction, especially prominent in radiative $D_{2}$ -seeded SF divertor, and nearly complete power detachment and broader radiated power distribution in the radiative $D_{2}$ -seeded SF divertor at $P_{\text {SOL}}=3-4$ MW. A variety of SF configurations can be supported by the divertor coil set in NSTX Upgrade. Edge transport modeling with the multifluid edge transport code UEDGE shows that the radiative SF divertor can successfully reduce peak divertor heat flux for the projected $P_{\text {SOL}} \simeq 9$ MW case. The radiative SF divertor with carbon impurity provides a wider $n_{e}$ operating window, 50% less argon is needed in the impurity-seeded SF configuration to achieve similar $q_{\text {peak}}$ reduction factors (see standard divertor).

DTT: a divertor tokamak test facility for the study of the power exhaust issues in view of DEMO

In parallel with the programme to optimize the operation with a conventional divertor based on detached conditions to be tested on the ITER device, a project has been launched to investigate alternative power exhaust solutions for DEMO, aimed at the definition and the design of a divertor tokamak test facility (DTT). The DTT project proposal refers to a set of parameters selected so as to have edge conditions as close as possible to DEMO, while remaining compatible with DEMO bulk plasma performance in terms of dimensionless parameters and given constraints. The paper illustrates the DTT project proposal, referring to a 6 MA plasma with a major radius of 2.15 m, an aspect ratio of about 3, an elongation of 1.6–1.8, and a toroidal field of 6 T. This selection will guarantee sufficient flexibility to test a wide set of divertor concepts and techniques to cope with large heat loads, including conventional tungsten divertors; liquid metal divertors; both conventional and advanced magnetic configurations (including single null, snow flake, quasi snow flake, X divertor, double null); internal coils for strike point sweeping and control of the width of the scrape-off layer in the divertor region; and radiation control. The Poloidal Field system is planned to provide a total flux swing of more than 35 Vs, compatible with a pulse length of more than 100 s. This is compatible with the mission of studying the power exhaust problem and is obtained using superconducting coils. Particular attention is dedicated to diagnostics and control issues, especially those relevant for plasma control in the divertor region, designed to be as compatible as possible with a DEMO-like environment. The construction is expected to last about seven years, and the selection of an Italian site would be compatible with a budget of 500 M€.

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