Emission Traces Research Articles

Near infrared characteristics of air plasma induced by nanosecond laser

The near infrared emission from laser induced air plasma has been investigated in a range of 1100–2400 nm. The infrared spectra of air plasma consist of linear spectral and continuum radiation. Most of the spectral features observed are identified, including atomic lines of O I and N I and molecular bands of N<sub>2</sub>. The spectra show trace of blackbody background emission and the plasma temperature is estimated from Planck law. We find that the continuum radiation is mainly origins mainly from the blackbody emission of plasma. There is a limitation of plasma temperature estimation by using Boltzmann method. For example, the local thermodynamic equilibrium must be satisfied, and the trend of change in plasma temperature can be estimated within a few microseconds after the laser shot. In this paper, the plasma temperature in 15 μs after laser irradiation is estimated from the Planck law, and the temperature of air plasma is estimated to be about 3900 K, which can compensate for the shortcomings of Boltzmann method. It is found that the neutral atomic spectra of N and O both may contribute to the radiation of the air plasma at 1128 nm. Then we keep the air pressure in the vacuum chamber at 80 kPa, and change the nitrogen and oxygen content in the chamber. The infrared spectrum data show that the oxygen content in the mixed gas only affect the radiation of 1128 nm wavelength. The binary linear regression analysis shows that oxygen contributes much to the radiation of 1128 nm wavelength. This can be explained by the difference in ionization potential between molecule O<sub>2</sub> and N<sub>2</sub>. The infrared radiation intensities of the air plasma at 1128 nm under 20−80 kPa are obtained, and they are compared with the calculated results obtained with the fitting formula. The predicted value is very close to the experimental value and the relative error is negligibly at the pressure of 30−80 kPa. The study of the characteristics of infrared emission from laser induced plasma is of great significance for understanding and using the physical mechanisms of laser-matter interaction.

Assessment of Efficiency of Eco-Friendly Organic Mosquito Repellent Developed using Elephant Dung

Mosquitoes transmit a range of infectious agents that affects human health. Malaria, dengue fever, yellow fever and other mosquito-borne diseases infect countless individuals and account for thousands of deaths annually, causing a large burden to public health and on the economic process of developing countries. At present, concerning 40% of the world’s populations mainly in India live in areas where the chance of dengue fever transmission is most. High rate of reproduction and lack of effective vaccines against several mosquito-borne pathogens makes us extremely addicted to the utilization of insecticides to manage the mosquito populations so as to prevent illness due to transmission. Mosquito repellents mainly consist of pyrethroids that lead to hyper excitation of nervous systems and its prolong usage results in corneal damage, liver damage and asthma. Hence, need for the development of the most effective organic herbal insect repellent must be taken into account due to the toxicity issues, together with the increased incidence of resistance to insects. In this perspective, the present study aimed to develop an eco-friendly mosquito repellent as an alternative for chemical repellent using elephant dung and other natural resources and to assess the efficiency of the organic repellant compared to commercial repellent. Elephant dung has being employed for fuel supply, biofertilizer and paper production. Natural ingredients like Nerium flowers, Tulsi, Neem leaves, Lemon grass oil and Natural loban were used in combination with the elephant dung to reinforce the potency of the mosquito repellent. Smoke toxicity of organic mosquito repellent was evaluated. Emission test for commercial and developed repellent was also compared and it is evident that there is 57% reduction in the carbon-di-oxide emission from developed repellent than commercial repellent and there are no traces of emission of carbon monoxide from the developed repellent. Also, cage test proves that the developed mosquito repellent is highly efficient against mosquitoes and hence can be more effectively used for control of mosquitoes.

Determining consumer's carbon emission obligation through virtual emission tracing in power systems

AbstractAlthough a recent report by the U.S. Energy Information Administration indicates that CO2 emissions from power generation have now fallen below emissions from the transportation sector, electricity use remains a significant part of human's environmental footprint since fossil fuels are the major energy resource for electricity generation worldwide. This explains the continual effort by policy makers to develop a remedy to mitigate carbon emissions. It is then critically important to properly account for the emissions associated with electricity generation, delivery, and consumption. In particular, it is critical to be able to allocate emissions to the relevant electricity consumers creating the demand that results in a polluting emission. Therefore, in this paper a virtual carbon emission tracing method in power systems is thoroughly presented to facilitate allotting carbon obligation. The method is developed based on the proportional sharing principle that has been used in power system operation. The proposed methodology is implemented on the IEEE 5‐bus and 9‐bus systems, two widely used and recognized power grid benchmarks.

Tracing the formation of molecular clouds via [C ii], [C i], and CO emission

Our understanding of how molecular clouds form in the interstellar medium (ISM) would be greatly helped if we had a reliable observational tracer of the gas flows responsible for forming the clouds. Fine structure emission from singly ionised and neutral carbon ([CII], [CI]) and rotational line emission from CO are all observed to be associated with molecular clouds. However, it remains unclear whether any of these tracers can be used to study the inflow of gas onto an assembling cloud, or whether they primarily trace the cloud once it has already assembled. In this paper, we address this issue with the help of high resolution simulations of molecular cloud formation that include a sophisticated treatment of the chemistry and thermal physics of the ISM. Our simulations demonstrate that both [CI] and CO emission trace gas that is predominantly molecular, with a density n ~ 500-1000 cm$^{-3}$, much larger than the density of the inflowing gas. [CII] traces lower density material (n ~ 100 cm$^{-3}$) that is mainly atomic at early times. A large fraction of the [CII] emission traces the same structures as the [CI] or CO emission, but some arises in the inflowing gas. Unfortunately, this emission is very faint and will be difficult to detect with current observational facilities, even for clouds situated in regions with an elevated interstellar radiation field.

Geochemistry and provenance of Neoproterozoic metasedimentary rocks from the Togo structural unit, Southeastern Ghana

Neoproterozoic metasedimentary rocks of greenshist facies, consisting predominantly of quartzites, phyllites, and phyllonites, occur in the Akwapim range of the Togo Structural Unit (TSU) in Ghana. The geochemistry of the phyllites were studied to determine their provenance and tectonic setting. The major element analysis was carried out by the Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and trace elements, including REEs, by the Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) method. The studied metasedimentary rocks have SiO2 and Al2O3 contents comparable to that of average Neoproterozoic upper crust. The metasedimentary rocks are strongly depleted in CaO, Na2O, and Sr and enriched in K2O, Ba and Rb with respect to average Neoproterozoic upper crust, reflecting K addition during diagenesis. Zr and Hf concentrations are significantly above Neoproterozoic upper crustal values. Chondrite-normalized rare earth element (REE) patterns are characterised by fractionated light-REE (LREE) (average LaN/SmN = 3.68), significant negative europium anomaly (average Eu/Eu* = 0.61) and fairly flat heavy-REE (HREE) (average GdN/YbN = 1.3). The geochemical data, particularly the high La/Sc, Th/Sc, La/Co, Th/Co, Zr/Sc, La/Th ratios, Eu/Eu* values, and high Zr and Hf concentrations, suggest that the metasedimentary rocks of the Togo Structural Units in the Akwapim range were derived mainly from recycled sedimentary sources. Comparison of geochemical signatures of the studied metasedimentary rocks with those of the Paleoproterozoic Birimian rocks suggests that the felsic materials in the Togo Structural Units (TSU) could not have been derived predominantly from the Birimian rocks, implying more distal sources. The studied metasedimentary rocks exhibit provenance characteristics similar to that of the Kwahu/Bombouaka Group of the Voltaian Basin, suggesting derivation from the same source, probably in the Amazon Craton. The metasedimentary rocks exhibit geochemical characteristics indicative of sediments derived from a passive continental margin. This inference supports previous studies that indicate that prior to the Pan-African Dahomeyide orogenic event, the southern margin of the West African Craton (WAC) was under passive margin settings.

ALMA Observations of the Massive Molecular Outflow G331.512-0.103. II. Physical Properties, Kinematics, and Geometry Modeling

We present observations and analysis of the massive molecular outflow G331.512-0.103, obtained with ALMA band 7, continuing the work from Merello et al. (2013). Several lines were identified in the observed bandwidth, consisting of two groups: lines with narrow profiles, tracing the emission from the core ambient medium; and lines with broad velocity wings, tracing the outflow and shocked gas emission. The physical and chemical conditions, such as density, temperature, and fractional abundances are calculated. The ambient medium, or core, has a mean density of $\sim 5\times 10^6$ cm$^{-3}$ and a temperature of $\sim 70$ K. The SiO and SO$_2$ emission trace the very dense and hot part of the shocked outflow, with values of $n_{\rm H_2}\sim10^9$ cm$^{-3}$ and $T \sim 160-200$ K. The interpretation of the molecular emission suggests an expanding cavity geometry powered by stellar winds from a new-born UCHII region, alongside a massive and high-velocity molecular outflow. This scenario, along with the estimated physical conditions, is modeled using the 3D geometry radiative transfer code MOLLIE for the SiO(J$=8-7$) molecular line. The main features of the outflow and the expanding shell are reproduced by the model.

A Very Compact Extremely High Velocity Flow toward MMS 5/OMC-3 Revealed with ALMA

Both high- and low-velocity outflows are occasionally observed around a protostar by molecular line emission. The high-velocity component is called `Extremely High-Velocity (EHV) flow,' while the low-velocity component is simply referred as `(molecular) outflow.' This study reports a newly found EHV flow and outflow around MMS $5$ in the Orion Molecular Cloud 3 observed with ALMA. In the observation, CO $J$=2--1 emission traces both the EHV flow ($|v_{\rm{LSR}} - v_{\rm{sys}}|$ $\simeq$ 50--100 $\rm{km\ s^{-1}}$) and outflow ($|v_{\rm{LSR}} - v_{\rm{sys}}|$ $\simeq$ 10--50 $\rm{km\ s^{-1}}$). On the other hand, SiO $J$=5--4 emission only traces the EHV flow. The EHV flow is collimated and located at the root of the V-shaped outflow. The CO outflow extends up to $\sim$ 14,000\,AU with a position angle (P.A.) of $\sim79^\circ$ and the CO redshifted EHV flow extends to $\sim$11,000 AU with P.A. $\sim96^\circ$. The EHV flow is smaller than the outflow, and the dynamical timescale of the EHV flow is shorter than that of the outflow by a factor of $\sim 3$. The flow driving mechanism is discussed based on the size, time scale, axis difference between the EHV flow and outflow, and the periodicity of the knots. Our results are consistent with the nested wind scenario, although the jet entrainment scenario could not completely be ruled out.

UVES Spectroscopy of T Chamaeleontis: Line Variability, Mass Accretion rate and Spectro-astrometric Analysis★

Although advances in exoplanet detection techniques have seen an increase in discoveries, observing a planet in the earliest stages of formation still remains a difficult task. Here four epochs of spectra of the transitional disk object T Cha are analysed to determine whether spectro-astrometry can be used to detect a signal from its proposed protoplanet, T Cha b. The unique properties of T Cha are also further constrained. H{\alpha} and [O I]{\lambda} 6300, the most prominent lines, were analysed using spectro-astrometry. H{\alpha} being a direct accretion tracer is the target for the T Cha b detection while [O I]{\lambda} 6300 is considered to be an indirect tracer of accretion. [O I]{\lambda} 6300 is classified as a broad low velocity component (BC LVC). The mass accretion rate was derived for all epochs using new [O I]{\lambda} 6300 LVC relationships and the H{\alpha} line luminosity. It is shown that a wind is the likely origin of the [O I]{\lambda} 6300 line and that the [O I]{\lambda} 6300 line serves as a better accretion tracer than H{\alpha} in this case. From the comparison between M acc([OI]) and M acc(H{\alpha}) it is concluded that T Cha is not an intrinsically weak accretor but rather that a significant proportion of the H{\alpha} emission tracing accretion is obscured. T Cha b is not detected in the spectro-astrometric analysis yet a detection limit of 0.5 mas is derived. The analysis in this case was hampered by spectro-astrometric artefacts and by the unique properties of T Cha. While it seems that spectro-astrometry as a means of detecting exoplanets in TDs can be challenging it can be used to put an limit on the strength of the H{\alpha} emission from accreting planetary companions and thus can have an important input into the planning of high angular resolution observations.

Jets blowing bubbles in the young radio galaxy 4C 31.04

We report the discovery of shocked molecular and ionized gas resulting from jet-driven feedback in the compact radio galaxy 4C 31.04 using near-IR imaging spectroscopy. 4C 31.04 is a $\sim 100$ pc double-lobed Compact Steep Spectrum source believed to be a very young AGN. It is hosted by a giant elliptical with a $\sim 10^{9}~\rm M_\odot$ multi-phase gaseous circumnuclear disc. We used high spatial resolution, adaptive optics-assisted $H$- and $K$-band integral field Gemini/NIFS observations to probe (1) the warm ($\sim 10^3~\rm K$) molecular gas phase, traced by ro-vibrational transitions of $\rm H_2$, and (2), the warm ionized medium, traced by the [Fe II]$_{1.644~\rm \mu m}$ line. The [Fe II] emission traces shocked gas ejected from the disc plane by a jet-blown bubble $300-400~\rm pc$ in diameter, whilst the $\rm H_2$ emission traces shock-excited molecular gas in the interior $\sim 1~\rm kpc$ of the circumnuclear disc. Hydrodynamical modelling shows that the apparent discrepancy between the extent of the shocked gas and the radio emission can occur when the brightest regions of the synchrotron-emitting plasma are temporarily halted by dense clumps, whilst less bright plasma can percolate through the porous ISM and form an energy-driven bubble that expands freely out of the disc plane. This bubble is filled with low surface-brightness plasma not visible in existing VLBI observations of 4C 31.04 due to insufficient sensitivity. Additional radial flows of jet plasma may percolate to $\sim \rm kpc$ radii in the circumnuclear disc, driving shocks and accelerating clouds of gas, giving rise to the $\rm H_2$ emission.

Direct tracing of NH3 and N2O emissions associated with urea fertilization approaches, using static incubation cells

Nitrogen fertilization contributes significantly to crop production globally. However, low efficiency application management approaches lead to substantial N losses of which ammonia and nitrous oxide are known as environmental threats. Urea, the largest N fertilization source globally, is associated with high ammonia losses. A large variety of application modes are practiced under different environmental conditions worldwide. Yet, the complexity of N-processes in different soils, under changing agro-environmental conditions, challenges the evaluation of fertilization approaches efficiency in reducing N-gaseous losses. In this research a simply designed static incubation cell was connected to a Long-Path gas cell and a Fourier Transform IR spectrometer (LP-FTIR), allowing online determination of ammonia and nitrous oxide emissions in parallel to tracking mineral N-dynamics in soil samples. The static chamber was used to evaluate different application approaches of urea (i.e., incorporation or surface application with or without wetting) in a Sandy Loam and to compare surface applied regular urea vs. urea amended with the urease inhibitors NPPT+NBPT [N-(n-butyl) thiophosphoric triamide and N-(n-propyl) thiophosphoric triamide, respectively] in four different representative soils. Ammonia emissions peaked few days after application, where highest losses were observed for surface application mode. Highest emissions, up to 5% (w/w) of applied Urea-N, were obtained with the lighter and more basic soils (Sandy Loam and Loess; pH > 7.9). Nitrous oxide emissions showed a lag period of ~1 week and were higher under lower urea application rates, and when nitrification was faster (~1–1.3% (w/w) of applied N). Urease inhibitors significantly reduced ammonia losses in all tested soils and particularly in the Sandy Loam and Loess. Their effect on nitrous oxide losses were observed with the Sandy Loam and particularly after 2 weeks. The static system may underestimate realistic ammonia losses, but it offers a rather simply operated system, providing information about N-gaseous losses for improving N-fertilization management.

Forming Super Star Clusters in the Central Starburst of NGC 253

Abstract NGC 253 hosts the nearest nuclear starburst. Previous observations show a region rich in molecular gas, with dense clouds associated with recent star formation. We used the Atacama Large Submillimeter/Millimeter Array (ALMA) to image the 350 GHz dust continuum and molecular line emission from this region at 2 pc resolution. Our observations reveal ∼14 bright, compact (∼2–3 pc FWHM) knots of dust emission. Most of these sources are likely to be forming super star clusters (SSCs) based on their inferred dynamical and gas masses, association with 36 GHz radio continuum emission, and coincidence with line emission tracing dense, excited gas. One source coincides with a known SSC, but the rest remain invisible in Hubble near-infrared (IR) imaging. Our observations imply that gas still constitutes a large fraction of the overall mass in these sources. Their high brightness temperature at 350 GHz also implies a large optical depth near the peak of the IR spectral energy distribution. As a result, these sources may have large IR photospheres, and the IR radiation force likely exceeds L/c. Still, their moderate observed velocity dispersions suggest that feedback from radiation, winds, and supernovae are not yet disrupting most sources. This mode of star formation appears to produce a large fraction of stars in the burst. We argue for a scenario in which this phase lasts ∼1 Myr, after which the clusters shed their natal cocoons but continue to produce ionizing photons. The strong feedback that drives the observed cold gas and X-ray outflows likely occurs after the clusters emerge from this early phase.

Experimental determination of equilibrium CH4–CO2–CO carbon isotope fractionation factors (300–1200 °C)

Carbon isotope fractionation in the CO2–CO–CH4–C system was investigated at 300–1200°C at near-atmospheric pressures by thermally decomposing a variety of organic materials in sealed quartz tubes. Measured gas speciations correspond well to the expected range from thermodynamic calculations. We show that chemical and isotopic equilibrium among gas species is obtained when applying a nickel catalyst for CO2/CH4, CH4/CO, and CO2/CO at ≤600°C or without a catalyzing agent for CO2/CO at ≥800°C. The experiments define carbon isotope fractionation factors for the CO2/CH4, CO2/CO and CH4/CO pairs as(i)103ln⁡αCO2/CH4=8.9(±0.6)⋅105⋅(1T2)0.825(±0.005) (200–1200°C)(ii)103ln⁡αCO2/CO=1.07(±0.05)⋅106⋅(1T2)0.830(±0.003) (300–1200°C)(iii)103ln⁡αCH4/CO=1.1(±0.2)⋅103⋅(1T2)0.462(±0.001) (300–1200°C), which reproduce the experimental values within 0.2‰ for CO2/CH4 and CO2/CO and within 0.12‰ for CH4/CO (T in K, 1σ fit uncertainties in brackets, CO2/CH4 includes the ≤600°C experimental data of Horita, 2001). Carbon isotope fractionation factors at 1000°C are still large for CO2/CH4 and CO2/CO (6.6 and 7.5‰, respectively) but only 1.5‰ for CH4/CO.Elemental carbon precipitated through thermal decomposition of the organic starting materials yields δ13C values that depend on the X(O) = O/(O + H) of the organic starting material, i.e. the initial oxidation state of carbon in the organics. We further observe a catalytic effect of the quartz walls on chemical and isotopic exchange in the CO2/CO system, probably due to the activation of the silicate surface by H+ and OH− ions at >650°C. Our experimental results yield improved calibrations of the CO2/CH4 equilibria and the first experimental calibration of CO2/CO and CH4/CO carbon isotope fractionation. Applications are in the tracing of magmatic hydrothermal gas emissions, in carbon-precipitating COH-fluids, and in monitoring of coal-seam fires, but our results may also be applied for quality control during steel-making processes.

Protostellar Outflows at the EarliesT Stages (POETS)

Context. Weak and compact radio continuum and H2O masers are preferred tracers of the outflow activity nearby very young stars. Aims. We want to image the centimeter free–free continuum emission in the range 1–7 cm (26–4 GHz), which arises in the inner few 1000 au from those young stars also associated with bright H2O masers. We seek to study the radio continuum properties in combination with the H2O maser kinematics to quantify the outflow energetics powered by single young stars. Methods. We made use of the Karl G. Jansky Very Large Array (VLA) in the B configuration at K band and the A configuration at both Ku and C bands in order to image the radio continuum emission toward 25 H2O maser sites with an angular resolution and thermal rms on the order of 0.′′1 and 10 μJy beam−1, respectively. These targets add to our pilot study of 11 maser sites previously presented. The sample of H2O maser sites was selected among those regions that have accurate distance measurements, obtained through maser trigonometric parallaxes, and H2O maser luminosities in excess of 10−6 L⊙. Results. We present high-resolution radio continuum images of 33 sources belonging to 25 star-forming regions. In each region, we detect radio continuum emission within a few 1000 au of the H2O masers’ position; 50% of the radio continuum sources are associated with bolometric luminosities exceeding 5 × 103 L⊙, including W33A and G240.32 + 0.07. We provide a detailed spectral index analysis for each radio continuum source, based on the integrated fluxes at each frequency, and produce spectral index maps with the multifrequency synthesis deconvolution algorithm of CASA. The radio continuum emission traces thermal bremsstrahlung in (proto)stellar winds and jets that have flux densities at 22 GHz below 3 mJy and spectral index values between − 0.1 and 1.3. We prove a strong correlation (r > 0.8) between the radio continuum luminosity (Lrad) and the H2O maser luminosity (LH2O) of (L8 GHz∕mJy kpc2) = 103.8 × (LH2O L⊙)0.74. This power-law relation is similar to that between the radio continuum and bolometric luminosities, which confirms earlier studies. Since H2O masers are excited through shocks driven by (proto)stellar winds and jets, these results provide support to the idea that the radio continuum emission around young stars is dominated by shock ionization, and this holds over several orders of magnitude of stellar luminosites (1–105 L⊙).

MAGNUM survey: A MUSE-Chandra resolved view on ionized outflows and photoionization in the Seyfert galaxy NGC1365

Context. Ionized outflows, revealed by broad asymmetric wings of the [O III] λ5007 line, are commonly observed in active galactic nuclei (AGN) but the low intrinsic spatial resolution of the observations has generally prevented a detailed characterization of their properties. The MAGNUM survey aims at overcoming these limitations by focusing on the nearest AGN, including NGC 1365, a nearby Seyfert galaxy (D ∼ 17 Mpc), hosting a low-luminosity active nucleus (Lbol ∼ 2 × 1043 erg s−1). Aims. We want to obtain a detailed picture of the ionized gas in the central ∼5 kpc of NGC 1365 in terms of physical properties, kinematics, and ionization mechanisms. We also aim to characterize the warm ionized outflow as a function of distance from the nucleus and its relation with the nuclear X-ray wind. Methods. We employed optical integral-field spectroscopic observations from VLT/MUSE to investigate the warm ionized gas and Chandra ACIS-S X-ray data for the hot highly-ionized phase. We obtained flux, kinematic, and diagnostic maps of the optical emission lines, which we used to disentangle outflows from gravitational motions in the disk and measure the gas properties down to a spatial resolution of ∼70 pc. We then performed imaging spectroscopy on Chandra ACIS-S data guided by the matching with MUSE maps. Results. The [O III] emission mostly traces a kpc-scale biconical outflow ionized by the AGN having velocities up to ∼200 km s−1. Hα emission traces instead star formation in a circumnuclear ring and along the bar, where we detect non-circular streaming gas motions. Soft X-rays are predominantly due to thermal emission from the star-forming regions, but we manage to isolate the AGN photoionized component which nicely matches the [O III] emission. The mass outflow rate of the extended ionized outflow is similar to that of the nuclear X-ray wind and then decreases with radius, implying that the outflow either slows down or that the AGN activity has recently increased. However, the hard X-ray emission from the circumnuclear ring suggests that star formation might in principle contribute to the outflow. The integrated mass outflow rate, kinetic energy rate, and outflow velocity are broadly consistent with the typical relations observed in more luminous AGN.

Combustion of Magnesium‐Sulfur Composite Particles Ignited by Different Stimuli

AbstractComposite Mg ⋅ S powders were prepared by mechanical milling. Magnesium powders coated with sulfur were prepared by soft milling using glass beads as milling media. Three‐dimensional composite powders, in which magnesium and sulfur were mixed on the nanoscale were prepared by milling using steel balls as milling media. Both composite powders were explored in two ignition experiments. In one case, monolayers of the prepared powders were exposed to electrostatic discharge (ESD). In the other case, powder particles were fed through a focused CO2 laser beam. In both experiments, emission traces produced by burning particles were captured using a filtered photomultiplier tube; the data were processed to recover respective combustion times. Combustion products were collected and examined using electron microscopy for the ESD‐ignition experiments. It was found that the burn times of the sulfur coated magnesium powders were shorter than those of three‐dimensional composites in both experiments. No effect of ignition method on burn times was observed for the sulfur‐coated powders. For three‐dimensional composite powder, burn times of ESD‐ignited particles were shorter than those for particles ignited by passing through the CO2 laser beam. Analysis of the captured combustion products suggests that magnesium and sulfur are readily separated upon heating for the coated powders, but not for the three‐dimensional composites. For the latter case, the reaction is dominated by MgS formation, while for the former case, it is primarily magnesium oxidation in air.

Neutron measurements at the ELISE neutral beam test facility and implications for neutron based diagnostics at SPIDER.

Along the route to the development of a neutral beam injector for ITER, the Padua based Source for Production of Ion of Deuterium Extracted from Rf plasma (SPIDER) and megavolt ITER injector and concept advancement facilities will make use of neutron diagnostics to quantify the homogeneity of the neutral beam profile by measuring the map of the neutron emission from the beam dump with the close-contact neutron emission surface mapping (CNESM) system. Neutrons are here produced from beam-target reactions between the deuterium beam and the deuterons previously adsorbed in the calorimeter. In order to aid the interpretation of the diagnostic data, a dedicated experiment on neutron emission from beam-target reactions with beam parameters approaching those expected at SPIDER has been performed at the Extraction from a Large Ion Source Experiment (ELISE) neutral beam test facility. The time trace of neutron emission has been measured using a calibrated liquid scintillator detector at increasing power densities on the target. Compared to calculations based on the local mixing model, a systematic discrepancy was observed exceeding the statistical accuracy of the measurements and increasing as a linear function of the power density. The data are used to derive an empirical temperature dependent correction for applications to neutron measurements at SPIDER.

Molecular filament formation and filament–cloud interaction: Hints from Nobeyama 45 m telescope observations

Abstract We present Nobeyama 45 m telescope C18O, 13CO, and 12CO(1–0) mapping observations towards an interstellar filament in the Taurus molecular cloud. We investigate the gas velocity structure along the filament and in its surrounding parent cloud. The filament is detected in the optically thin C18O emission as a single velocity component with a ∼1 pc long, ∼0.06 pc wide structure. The C18O emission traces dust column densities larger than ∼5 × 1021 cm−2. The line-of-sight (LOS) velocity fluctuates along the filament crest with an average amplitude of ∼0.2 km s−1. The 13CO and 12CO integrated intensity maps show spatially extended emission around the elongated filament. We identify three extended structures with LOS velocities redshifted and blueshifted with respect to the average velocity of the filament identified in C18O. Based on combined analyses of velocity-integrated channel maps and intensity variations of the optically thick 12CO spectra on and off the filament, we propose a three-dimensional structure of the cloud surrounding the filament. We further suggest a multi-interaction scenario where sheet-like extended structures interact, in space and time, with the filament and are responsible for its compression and/or disruption, playing an important role in the star formation history of the filament. We also identify, towards the same field, a very faint filament showing a velocity field compatible with the filament formation process proposed by Inoue et al. (2018, PASJ, 70, S53), where a filament is formed due to convergence of a flow of matter generated by the bending of the ambient magnetic field structure induced by an interstellar shock compression.

The Distinct Evolutionary Nature of Two Class 0 Protostars in Serpens Main SMM4

Abstract We have observed the submillimeter continuum condensation SMM4 in Serpens Main using the Atacama Large Millimeter/submillimeter Array during its Cycle 3 in 1.3 mm continuum, 12CO J = 2–1, SO J N = 65–54, and C18O J = 2–1 lines at angular resolutions of ∼0.″55 (240 au). The 1.3 mm continuum emission shows that SMM4 is spatially resolved into two protostars embedded in the same core: SMM4A showing a high brightness temperature, 18 K, with little extended structure and SMM4B showing a low brightness temperature, 2 K, with compact and extended structures. Their separation is ∼2100 au. Analysis of the continuum visibilities reveals a disk-like structure with a sharp edge at r ∼ 240 au in SMM4A, and a compact component with a radius of 56 au in SMM4B. The 12CO emission traces fan-shaped and collimated outflows associated with SMM4A and SMM4B, respectively. The blue and red lobes of the SMM4B outflow have different position angles by ∼30°. Their inclination and bending angles in the 3D space are estimated at i b ∼ 36°, i r ∼ 70°, and α ∼ 40°, respectively. The SO emission traces shocked regions, such as cavity walls of outflows and the vicinity of SMM4B. The C18O emission mainly traces an infalling and rotating envelope around SMM4B. The C18O fractional abundance in SMM4B is ∼50 times smaller than that of the interstellar medium. These results suggest that SMM4A is more evolved than SMM4B. Our studies in Serpens Main demonstrate that continuum and line observations at millimeter wavelengths allow us to differentiate evolutionary phases of protostars within the Class 0 phase.

Multi-Stage Evolution of Gold-Bearing Hydrothermal Quartz Veins at the Mokrsko Gold Deposit (Czech Republic) Based on Cathodoluminescence, Spectroscopic, and Trace Elements Analyses

We performed a detailed analysis of hydrothermal quartz at the Mokrsko gold deposit (Čelina, Mokrsko-East, and Mokrsko-West deposits). Twenty-one samples were studied by scanning electron microscopy cathodoluminescence (CL) imagining, CL emission spectra and trace elements were measured on six selected samples. Four quartz growth generations Q1 to Q4 were described. Homogeneous early blue CL Q1 with initial emission spectra at 380 and 500 nm was observed at the Čelina deposit with typical titanium concentrations in the range of 20–50 ppm. Hydrothermal quartz at Mokrsko-West, which also includes early Q1, late subhedral faces of yellow CL Q2, and microfissures of greenish CL Q3 (both 570 nm), is characterized by titanium depletion. The titanium concentration is comparable to previous studies of crystallization temperatures proving titanium concentration in quartz as a good geothermal indicator. Q4, developed in microfissures only at Čelina, has no visual CL effect. Mokrsko-West is specific in comparison to Mokrsko-East and Čelina by germanium enrichments in hydrothermal quartz (up to 17 ppm) and the presence of fluorite. Tectonic (sheeted veinlets system, regional tectonic setting) and geochemical (germanium in quartz, the presence of fluorite) characteristics of the quartz veins link the late mineralization stages at the Mokrsko-West deposit to the temporally related Blatná intrusive suite.

Quota-based carbon tracing model for construction processes in China

Carbon emissions contribute substantially to climate change. Many researchers believe that the construction industry can contribute significantly to carbon dioxide reduction through cleaner and more sustainable building production and construction, e.g. low energy building design and the use of low carbon materials. Nonetheless, the environmental impacts associated with construction process should not be underestimated. Despite that, as construction process is complex and involves many participants, the calculation of carbon emissions during the construction process is never an easy task. Divergence and limitation are found in both the system boundary and carbon sourcing method. This research aims to resolve the problem and facilitate construction managers to identify carbon emissions so as to optimize them through better construction arrangement. In this paper, the system boundary of the construction stage is first defined and the related activities being included in the construction process are identified. A methodology of establishing the sources of carbon emissions during the construction process based on a quota-based method of China is proposed. The calculation model for carbon emissions is established according to the traditional emission factor approach with some modifications. The carbon emitted during the construction process of a case teaching building is calculated using the proposed quota-based carbon tracing (QCT) model. The QCT model not only provides a systematic framework for the tracing of carbon emissions, it could also help construction managers identify low carbon construction methods and logistics schedule in order to maximize the carbon reduction opportunity during the construction stage.