bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppressing the enhancement of stimulated Raman scattering in inhomogeneous plasmas by tuning the modulation frequency of a broadband laser
Authors: Wen H. , Follett R. K. , Maximov A. V. , Froula D. H. , Tsung F. S. , Palastro J. P.
Published: April 2021

The stimulated Raman scattering (SRS) instability can inhibit the performance of laser-driven inertial confinement fusion (ICF) implosions by scattering light into unwanted directions or by generating hot electrons that preheat the target fuel. In principle, ICF target designs can avoid parameter regimes conducive to large, linear SRS gains. In practice, kinetic inflation—the nonlinear enhancement of SRS due to electron trapping in the excited plasma wave—makes this difficult. Here, we show that laser bandwidth in the form of frequency modulation can either decrease or increase the inflationary SRS (iSRS) threshold in inhomogeneous plasmas depending on the maximum chirp of the laser pulse. The threshold, mapped out by a series of particle-in-cell simulations, exhibits a minimum when the frequency change within the pulse cancels the spatial detuning due to density inhomogeneities along the trajectory of the scattered light. By tuning the pump laser parameters away from this minimum, the iSRS threshold can be larger than at zero bandwidth, providing a path to mitigating kinetic inflation in ignition relevant plasmas.
Diagnosing plasma magnetization in inertial confinement fusion implosions using secondary deuterium-tritium reactions
Authors: Sio H. , Moody J. D. , Ho D. D. , Pollock B. B. , Walsh C. A. , Lahmann B. , Strozzi D. J. , Kemp G. E. , Hsing W. W. , Crilly A. , Chittenden J. P. , Appelbe B.
Published: April 2021

Diagnosing plasma magnetization in inertial confinement fusion implosions is important for understanding how magnetic fields affect implosion dynamics and to assess plasma conditions in magnetized implosion experiments. Secondary deuterium–tritium (DT) reactions provide two diagnostic signatures to infer neutron-averaged magnetization. Magnetically confining fusion tritons from deuterium–deuterium (DD) reactions in the hot spot increases their path lengths and energy loss, leading to an increase in the secondary DT reaction yield. In addition, the distribution of magnetically confined DD-triton is anisotropic, and this drives anisotropy in the secondary DT neutron spectra along different lines of sight. Implosion parameter space as well as sensitivity to the applied B-field, fuel ρR, temperature, and hot-spot shape will be examined using Monte Carlo and 2D radiation-magnetohydrodynamic simulations.
Analysis of magnetohydrodynamic channel flow through complex network analysis
Authors: Charakopoulos Avraam , Karakasidis Theodoros , Sarris Ioannis
Published: April 2021

Velocity time series of hydrodynamic and magnetohydrodynamic (MHD) turbulent flow are analyzed by means of complex network analysis in order to understand the mechanism of fluid patterns modification due to the external magnetic field. Direct numerical simulations of two cases are used, one for the plane hydrodynamic turbulent channel flow at the low Reynolds number of 180, based on the friction velocity, and the corresponding MHD flow with an external streamwise magnetic field with a magnetic interaction number of 0.1. By applying the visibility graph algorithm, we first transformed the time series into networks and then we evaluated the network topological properties. Results show that the proposed network analysis is not only able to identify and detect dynamical transitions in the system's behavior that identifies three distinct fluid areas in accordance with turbulent flow theory but also can quantify the effect of the magnetic field on the time series transitions. Moreover, we find that the topological measures of networks without a magnetic field and as compared to the one with a magnetic field are statistically different within a 95% confidence interval. These results provide a way to discriminate and characterize the influence of the magnetic field on the turbulent flows.
Excited-state dynamics of [Mn(im)(CO)3(phen)]+: PhotoCORM, catalyst, luminescent probe?
Authors: Fumanal Maria , Daniel Chantal , Gindensperger Etienne
Published: April 2021

Mn(I) α-diimine carbonyl complexes have shown promise in the development of luminescent CO release materials (photoCORMs) for diagnostic and medical applications due to their ability to balance the energy of the low-lying metal-to-ligand charge transfer (MLCT) and metal-centered (MC) states. In this work, the excited state dynamics of [Mn(im)(CO)3(phen)]+ (im = imidazole; phen = 1,10-phenanthroline) is investigated by means of wavepacket propagation on the potential energy surfaces associated with the 11 low-lying Sn singlet excited states within a vibronic coupling model in a (quasi)-diabatic representation including 16 nuclear degrees of freedom. The results show that the early time photophysics (<400 fs) is controlled by the interaction between two MC dissociative states, namely, S5 and S11, with the lowest S1–S3 MLCT bound states. In particular, the presence of S1/S5 and S2/S11 crossings within the diabatic picture along the Mn–COaxial dissociative coordinate (qMn–COaxial) favors a two-stepwise population of the dissociative states, at about 60–70 fs (S11) and 160–180 fs (S5), which reaches about 10% within 200 fs. The one-dimensional reduced densities associated with the dissociative states along qMn–COaxial as a function of time clearly point to concurrent primary processes, namely, CO release vs entrapping into the S1 and S2 potential wells of the lowest luminescent MLCT states within 400 fs, characteristics of luminescent photoCORM.
Sliding homoclinic bifurcations in a Lorenz-type system: Analytic proofs
Authors: Belykh Vladimir N. , Barabash Nikita V. , Belykh Igor V.
Published: April 2021

Non-smooth systems can generate dynamics and bifurcations that are drastically different from their smooth counterparts. In this paper, we study such homoclinic bifurcations in a piecewise-smooth analytically tractable Lorenz-type system that was recently introduced by Belykh et al. [Chaos 29, 103108 (2019)]. Through a rigorous analysis, we demonstrate that the emergence of sliding motions leads to novel bifurcation scenarios in which bifurcations of unstable homoclinic orbits of a saddle can yield stable limit cycles. These bifurcations are in sharp contrast with their smooth analogs that can generate only unstable (saddle) dynamics. We construct a Poincaré return map that accounts for the presence of sliding motions, thereby rigorously characterizing sliding homoclinic bifurcations that destroy a chaotic Lorenz-type attractor. In particular, we derive an explicit scaling factor for period-doubling bifurcations associated with sliding multi-loop homoclinic orbits and the formation of a quasi-attractor. Our analytical results lay the foundation for the development of non-classical global bifurcation theory in non-smooth flow systems.
An a priori analysis of the structure of local subfilter-scale species surrounding flame fronts using direct numerical simulation of turbulent premixed flames
Authors: Shah Yash G. , Brasseur James G. , Xuan Yuan
Published: April 2021

An a priori analysis of subfilter-scale (SFS) species structure important to estimate chemical reaction rates in large-eddy simulation (LES) is performed using direct numerical simulation (DNS) of a turbulent premixed flame at a turbulence Reynolds number Re0=329 and Karlovitz number Ka0=7.23 with semi-detailed finite-rate chemistry. Differences between the complete chemical reaction rates extracted from DNS and those estimated from LES-filtered variables are quantified. The spatial distributions of these differences are found to be localized in regions surrounding the flame front for representative reactions. Within these regions, variations in the localization relative to the flame, scale, and magnitude of the SFS species concentrations are quantified, and mean SFS structure is determined. SFS species structure is found in two groupings: “single-banded” structure characterized by one distinct peak and “double-banded” structure characterized by two peaks of opposite signs. Species that are produced and consumed within the flame such as CH2O and HCO are observed to have single-banded structure, and species displaying a frontal behavior such as n-C7H16 and OH are found to have double-banded structure, on average. The local SFS structure surrounding the flame is impacted by neighboring flame-flame interactions as well as by variations in flame curvature. The impacts of the flame-flame interactions are strong when the SFS species structure has “large” length scales with concentration peaks significantly displaced from the flame front. Curvature effects are shown to be strong in high curvature regions of the flame.
Interplay between superconductivity and the Kondo effect on magnetic nanodots
Authors: Yang Hyunsoo , Choi Mahn-Soo , Ilnicki Grzegorz , Martinek Jan , Yang See-Hun , Parkin Stuart
Published: April 2021

We study the interplay of superconductivity, ferromagnetism, and the Kondo effect in a single system, using vertical geometry and planar magnetic tunnel junction devices, in which a thin CoFe layer is inserted in the middle of the MgO layer, forming a quantum dot like system. It is shown that the Kondo resonance peak at the zero bias coexists with a sharp Bardeen-Cooper-Schrieffer gap on double tunnel junctions, Al/MgO/CoFe nanodot/MgO/Al. It is also found that the competition between superconductivity and the Kondo effect is tunable with magnetic fields and the temperature. The coexistence of Kondo screening and superconductivity survives long range magnetic order in CoFe nanodots with a spin polarization of 0.2; however, it disappears when the CoFe layer becomes a continuous film with a spin polarization of 0.5. The competition between SC and the Kondo effect in the presence of magnetic ordering opens exciting possibilities to control information in nanomagnets.
Effect of space charge on vacuum pre-breakdown voltage and electron emission current
Authors: Seznec B. , Dessante Ph. , Teste Ph. , Minea T.
Published: April 2021

The recent developments in nanosecond pulsed power supplies facilitate the emission of high density electron bursts but their safe operation demands avoiding breakdowns. Using the theoretical and numerical modeling of the electron emission phenomena from a tip (micro-protrusion), the breakdown threshold (pre-breakdown) is analyzed considering it as the highest value of the voltage preserving the system out of the thermo-emission instability regime. However, the space charge that builds up in front of the tip limits the performance of these electron sources by decreasing the local electric field and consequently the thermo-field emission as well as the temperature of the emissive surface. Hence, it is found that the system can safely hold higher voltages (without breakdown) in the presence of dense space charge. In direct current, for a titanium elliptic tip, the highest operation voltage increases by about 15%, whereas for a tungsten hyperbolic tip, it increases by 70%. Remarkably, the emitted current close to the pre-breakdown voltage stays unchanged with or without taking into account the space charge. Surprisingly, when very short pulses (3 ns) are applied to a tungsten hyperbolic tip, the pre-breakdown voltage additionally increases by 30%, and the Coulomb screening, very effective in front of the tip apex, enlarges the electron emission area by 60%, releasing about 1.3 times more electrons compared to vacuum emission (without the space charge). Moreover, the ring effect, experimentally discovered by Dyke and Trolan [Phys. Rev. 89, 799 (1953)] on the radial electron density distribution, can be microscopically observed and understood with your model.
Study on boiling heat transfer in a shear flow through the lattice Boltzmann method
Authors: Nie Deming , Guan Geng
Published: April 2021

The liquid–vapor phase change and the boiling heat transfer induced by a microheater in a fluid are numerically studied through a two-phase lattice Boltzmann method. The fluid is subjected to simple shear. The effects of the gravity force, flow strength, and wall wettability are taken into account. A direct comparison between the cases of pool boiling and flow boiling is made in terms of the bubble release period, flow features, and the temperature of the microheater. In particular, it is shown that the flow motion has a negligible effect on the bubble release period for hydrophilic surfaces. By contrast, the bubble departure is considerably accelerated by the shear flow for hydrophobic surfaces which is associated with the formation of “bubble neck.”
Metabolite investments and stress levels among tissue compartments of
Authors: Naves Guilherme de Faria Silva , Kuster Vinícius Coelho , Machado Mariana , Santos Patrícia Dias , Martini Vitor Campana , Oliveira Denis Coelho
Published: April 2021

Galling insects manipulate host plant tissues for their own benefit. Because of feeding activity of the gall insects, both structural and metabolic changes occur in the host plant, leading to the formation of an abnormal growth of new organ (the gall). Galls induced by Palaeomystella oligophaga (Lepidoptera) on Macairea radula (Melastomataceae) depend on the constant larval feeding stimulus for establishment and development. The gall consists of two tissue compartments – the storage and nutritive tissues. These two gall tissues were investigated here in terms of the levels of oxidative stress and of a possible differential chemical investment. In addition, we investigated the relationship between gall coloration and the concentration of primary metabolites. Our results supported a differential investment of chemical compounds in the M. radula compartments, with higher concentrations of polysaccharides, malondialdehyde, and phenolic compounds in the storage tissue, and higher total soluble sugar concentrations in the nutritive tissue. Regarding gall colour, conflicting results were observed in the present gall system. Water-soluble polysaccharides were detected at higher concentrations in red galls than in green galls. As a water-soluble polysaccharide, pectin seems to be related to increased anthocyanin stability, a process that might occur in galls, leading to red coloration.
E2A-regulated epigenetic landscape promotes memory CD8 T cell differentiation
Authors: Schauder David M. , Shen Jian , Chen Yao , Kasmani Moujtaba Y. , Kudek Matthew R. , Burns Robert , Cui Weiguo
Published: April 2021

Significance

Following an acute viral infection, the majority of activated virus-specific CD8 T cells die off, while a smaller subset survives and develops into long-lived memory CD8 T cells. The underlying process regulation of this cell fate decision remains incompletely understood. In this study, we identify two main patterns of gene regulatory networks underlying effector and memory CD8 T cell differentiation. Furthermore, enhancer activity correlates with these regulon patterns. Finally, cells destined to become memory CD8 T cells maintain accessibility at enhancers regulating key memory-related genes, and the transcription factor E2A regulates the accessibility of many memory-related enhancers to promote memory cell formation.
Host barriers to SARS-CoV-2 demonstrated by ferrets in a high-exposure domestic setting
Authors: Sawatzki Kaitlin , Hill Nichola J. , Puryear Wendy B. , Foss Alexa D. , Stone Jonathon J. , Runstadler Jonathan A.
Published: April 2021

Significance

Ferrets have been demonstrated to be susceptible to laboratory infection of SARS-CoV-2, raising the possibility of natural transmission from humans into their pets in domestic settings. We demonstrate that ferrets may have host barriers that limit natural infection and transmission. First, we find no evidence of infection in 29 ferrets from a home with constant exposure to two adults with one confirmed and one suspected case of symptomatic COVID-19. Second, we analyze genetic sequences from viruses and hosts and demonstrate that ferrets have genetic factors that confer resistance to natural SARS-CoV-2 infection. These data suggest that ferret infection may require viral adaptation, and therefore ferrets may only be semipermissive models of SARS-CoV-2 disease or transmission.
Evaluation of Spin in the Abstracts of Systematic Reviews and Meta-Analyses of Studies on Opioid use Disorder
Authors: Balcerak Greg , Shepard Samuel , Ottwell Ryan , Arthur Wade , Hartwell Micah , Beaman Jason , Lu Kaelyn , Zhu Lan , Wright Drew N. , Vassar Matt
Published: April 2021

Background

Spin, or the inappropriate formatting of information to emphasize certain outcomes, should not be present in research. This study focuses on identifying and characterizing the presence of spin in systematic review and meta-analysis abstracts that focus on the treatment of opioid use disorder.

Methods

Search strategies were developed to identify studies pertaining to the treatment of opioid use disorder. The studies were then screened by two authors. These qualifying studies were then evaluated for the presence of spin within their abstracts by two trained authors. These studies were also evaluated by the AMSTAR-2 standards to evaluate the quality of the qualifying systematic reviews by two trained reviewers.

Results

The sample in this study included 113 systematic reviews and meta-analyses. Spin was present in 20 of these studies (20/113, 17.7%). The most common spin form was spin type 3 (6/20, 30%), followed by types 5 and 9 (both 4/20, 20%), type 6 (3/20, 15%), type 7 (2/20, 10%), and type 8 (1/20, 5%). The remaining spin types 1, 2, and 4 were not present in the sample. Of the 113 included studies, the most common intervention type was pharmacologic (93/113, 82%). No significant association was found between the quality of a systematic review and the presence of spin.

Conclusions

Findings in this study show positive trends in prevalence of five forms of spin evaluated in abstracts of systematic reviews and meta-analyses looking at treatments for opioid use disorder. However, study quality had no significant association with the presence of spin. Misrepresentation of results, or spin, may alter a clinician's perceptions about treatment efficacies. Therefore, increasing physician awareness of spin may improve clinical decision-making.
Reconstruction of multipolar point sources with multi-frequency sparse far field data
Authors: Ji Xia
Published: April 2021

The inverse acoustic scattering of point sources using multi-frequency sparse far field patterns is studied. The object may be a sum of monopoles and dipoles. We show that the locations and scattering strengths of the point sources can be uniquely identified by the multi-frequency far fields taken at sparse observation directions. Based on the uniqueness analyses, two schemes are proposed to distinguish the dipoles and monopoles, locate the positions and recover the scattering strengths. Numerical examples in two dimensions are presented to validity the effectiveness and robustness of the proposed methods. In particular, the numerical reconstructions indicate that the proposed methods are fast, stable and independent of the types, number or positions of the unknown point sources.
Passivation of thermally-induced defects with hydrogen in float-zone silicon
Authors: De Guzman J A T , Markevich V P , Hiller D , Hawkins I D , Halsall M P , Peaker A R
Published: April 2021

In this study, passivation of thermally-activated recombination centers with hydrogen in n-type float zone (FZ) Si containing nitrogen has been investigated. Prior to hydrogenation samples were heated to 550 °C using rapid thermal annealing and conventional furnaces. A large decrease in minority carrier lifetime occurred upon the heat-treatments confirming previous reports. A sequence of electron traps created in this process have been detected in the deep level transient spectra and characterized. Significant changes in the spectra have occurred after treatments in remote hydrogen plasma and subsequent annealing of the hydrogenated samples in the temperature range 100 °C–400 °C. A total elimination of electrical activity of the thermally induced defects has been observed in the hydrogenated samples subjected to annealing in the temperature range 150 °C–300 °C. The results obtained suggest a simple way for an effective cure of the degraded FZ-Si-based solar cells. Possible defect reactions occurring in the FZ-Si crystals and the role of nitrogen and carbon upon the performed treatments are discussed.
The effects of process parameters on melt-pool oscillatory behaviour in gas tungsten arc welding
Authors: Ebrahimi Amin , Kleijn Chris R , Hermans Marcel J M , Richardson Ian M
Published: April 2021

Internal flow behaviour and melt-pool surface oscillations during arc welding are complex and not yet fully understood. In the present work, high-fidelity numerical simulations are employed to describe the effects of welding position, sulphur concentration (60–300 ppm) and travel speed (1.25–5 mms−1) on molten metal flow dynamics in fully-penetrated melt-pools. A wavelet transform is implemented to obtain time-resolved frequency spectra of the oscillation signals, which overcomes the shortcomings of the Fourier transform in rendering time resolution of the frequency spectra. Comparing the results of the present numerical calculations with available analytical and experimental datasets, the robustness of the proposed approach in predicting melt-pool oscillations is demonstrated. The results reveal that changes in the surface morphology of the pool resulting from a change in welding position alter the spatial distribution of arc forces and power-density applied to the molten material, and in turn affect flow patterns in the pool. Under similar welding conditions, changing the sulphur concentration affects the Marangoni flow pattern, and increasing the travel speed decreases the size of the pool and increases the offset between top and bottom melt-pool surfaces, affecting the flow structures (vortex formation) on the surface. Variations in the internal flow pattern affect the evolution of melt-pool shape and its surface oscillations.
Harvesting wind energy with a bi-stable configuration integrating vortex-induced vibration and galloping
Authors: Wang Yuansheng , Zhou Zhiyong , Qin Weiyang , Zhu Pei
Published: April 2021

This paper proposed a wind energy harvester that integrates the merits of vortex-induced vibration (VIV), galloping and multi-stability. Two different shapes of bluff bodies are introduced to induce VIV and galloping for incoming flow, respectively. Three magnets are placed on the beam and fixture so as to generate bi-stability by magnetic attraction. As the wind blows through, the induced aero-dynamical instability leads the piezoelectric beam to oscillate and execute snap-through motion, which could generate a large electric output. The validation experiment was conducted. The experimental results show that as the flow speed increases from v= 1.0 m s−1 to 7.0 m s−1, the harvester could begin snap-through motion from a low speed v = 1.5 m s−1, and maintain the coherence resonance motion within a broad range of wind speed. Thus, it could maintain the large output in the environment of variable-speed wind.
Inference of plasma parameters from fixed-bias multi-needle Langmuir probes (m-NLP)
Authors: Guthrie Joshua , Marchand Richard , Marholm Sigvald
Published: April 2021

New approaches are presented to infer plasma densities and satellite floating potentials from currents collected with fixed-bias multi-needle Langmuir probes (m-NLP). Using synthetic data obtained from kinetic simulations, comparisons are made with inference techniques developed in previous studies and, in each case, model skills are assessed by comparing their predictions with known values in the synthetic data set. The new approaches presented rely on a combination of an approximate analytic scaling law for the current collected as a function of bias voltage, and multivariate regression. Radial basis function regression (RBF) is also applied to Jacobsen et al’s procedure (2010 Meas. Sci. Technol.
21 085902) to infer plasma density, and shown to improve its accuracy. The direct use of RBF to infer plasma density is found to provide the best accuracy, while a combination of analytic scaling laws with RBF is found to give the best predictions of a satellite floating potential. In addition, a proof-of-concept experimental study has been conducted using m-NLP data, collected from the Visions-2 sounding rocket mission, to infer electron densities through a direct application of RBF. It is shown that RBF is not only a viable option to infer electron densities, but has the potential to provide results that are more accurate than current methods, providing a path towards the further use of regression-based techniques to infer space plasma parameters.
Retracted: Synthesis and surface modification of mesoporous metal-organic framework (UiO-66) for efficient pH-responsive drug delivery and lung cancer treatment
Authors: Xie Canguo , Guo Bitao , You Hua , Wang Zhengyan , Leng Qiqi , Ding Lijun , Wang Qi
Published: April 2021

This paper applied mesoporous metal-organic frameworks (MOFs) of UiO-66 particles for pH-responsive doxorubicin (DOX) delivery and cancer treatment. Mesoporous structured UiO-66 MOFs were synthesized, and carboxymethylcellulose (CMC) was loaded for sensitive pH response and also as a linker to encapsulate the chemotherapeutic drug of DOX. The composite of UiO-66/CMC@DOX was synthesized, and the loading capacity was as high as 45 μg DOX per mg of the carrier. The structure and crystalization of the UiO-66 MOFs were determined by the Transmitting Electron Microscope (TEM) and x-ray diffraction methods, while the loading of CMC and DOX was inspected by Fourier Transform InfraRed (FT-IR) and UV–vis spectroscopy. The DOX release from UiO-66/CMC@DOX was tested under different pH at 37 °C. The DOX accumulative release could reach 78% under the pH of 5. A lower pH was more favorable for DOX release due to the CMC shrinking and higher DOX solubility in an acidic environment. The cytotoxicity study indicated that, under the DOX concentration of 4 μg ml−1, the A549 cell (Lung Carcinoma Cell Line) viability of UiO-66/CMC was 28%, which was lower than that from free DOX solution (47%). UiO-66 MOFs were demonstrated to be an efficient drug delivery carrier for chemotherapeutic drug and release.
Nanotwinning and tensile behavior in cold-welded high-entropy-alloy nanowires
Authors: Cui Yi , Toku Yuhki , Ju Yang
Published: April 2021

Since the fabrication technique for high-entropy alloy (HEA) nanowires/nanopillars is still in its infancy, neither experimental nor modeling analyses of their cold-welding performance have been reported. Based on insights accumulated in our previous experiments and simulations regarding cold-welded metallic nanowires, in this study, the cold-welding performance of HEA nanowires is probed by atomistic simulations. Among different materials, our simulations reveal that extensively twinned structures are formed in CoCrMnFeNi samples, but not in CoCrCuFeNi or Ni samples. The larger fracture strain in certain HEAs is due to the improved ductility around the fracturing area as well as multiple twinning. Unlike in Ni samples, the fracture strains in HEA samples, regardless of being cuboid or cylindrical, are improved by shrinking the sample size. Among different orientations, the [010]-direction monocrystalline nanowires fail at a strain over 0.6, which is almost double that of the [111] direction. The fracture strains in polycrystalline HEA samples are, on average, larger than those in polycrystalline Ni samples. Furthermore, fracture strains in randomly generated polycrystalline HEA samples are more predictable than those in polycrystalline Ni samples with identical grain configurations. As previously reported, dislocation emission is still a prerequisite to fracture in all cold-welded samples.
Z-scheme polyimide/tungsten trioxide aerogel photocatalyst for enhanced photocatalytic CO2 reduction under visible light
Authors: Zhao Xinfu , Yi Xibin , Zhang Jing , Liu Benxue , Yu Shimo , Liu Xiaochan
Published: April 2021

Developing highly efficient and stable photocatalysts is an effective method to achieve CO2 photocatalytic reduction. Herein, PI/WO3 aerogel photocatalyst was prepared by chemical amide reaction coupled with an ethanol supercritical drying technique. The novel aerogel photocatalysts exhibit excellent photocatalytic performance for reducing CO2 into CO. In particular, PI/WO3-10 aerogel photocatalyst shows the highest yield of CO (5.72 μmol g–1 h–1), which is ca 11-fold higher than that of the pristine PI aerogel. The high CO2 reduction activity can be attributed to the Z-scheme structure, which enhances the separation of photo-generated electron–holes, and induces H2O oxidation on WO3 nanosheets and CO2 reduction on PI aerogel. The photocatalytic reaction mechanism of CO2 when using PI/WO3 aerogel photocatalyst is proposed.
Probing the Atmospheric Precipitable Water Vapor with SOFIA. II. Atmospheric Models from ECMWF
Authors: Iserlohe C. , Fischer C. , Vacca W. D. , Fischer N. , Colditz S. , Krabbe A.
Published: April 2021

SOFIA is an airborne observatory for far-infrared astronomy. Although SOFIA flies at altitudes of ∼41,000 feet, any far-infrared observations from within the Earth’s atmosphere are nevertheless hampered by water vapor absorbing the astronomical signal. The atmospheric parameter governing absorption is the total upward precipitable water vapor, PWV. In this paper we investigated if data of the Earth’s atmosphere provided by the European Centre for Medium-Range Weather Forecasts, ECMWF, can be used to determine spatially and time-resolved PWV data to allow a more precise calibration of far-infrared data taken with SOFIA along its flight path. We found that PWV values obtained from ECMWF correlate extremely well with independently determined PWV values obtained with the FIFI-LS instrument onboard SOFIA. We determined maximum observing time intervals (depending on the pressure altitude SOFIA is flying at) within which the upward PWV value changes inflight by less than a certain amount. We also present a new calibration method which enhances data quality and observing efficiency with FIFI-LS significantly. Furthermore our new method is universal and may be applied to data from all of SOFIA's instruments.
Excitation of zonal flow by intermediate-scale toroidal electron temperature gradient turbulence
Authors: Chen Haotian , Tirkas Stefan , Parker Scott E.
Published: April 2021

On the basis of gyrokinetic theory, we derive nonlinear equations for the zonal flow (ZF) generation in intermediate-scale electron temperature gradient (ETG) turbulence (with wavelength much shorter than the ion Larmor radius but much longer than the electron Larmor radius) in nonuniform tokamak plasmas. Both the spontaneous and forced generation of ZFs are kept on the same footing. The resultant Schrödinger equation for the ETG amplitude is characterized by a Navier–Stokes type nonlinearity, which is typically stronger than the Hasegawa–Mima type nonlinearity resulting from the fluid approximation. The physics underlying the three stages of ZF generation process is clarified, and the role of parallel mode structure decoupling is discussed. It is found that ZFs can be more easily excited in the intermediate-scale ETG turbulence than in the short wavelength regime.
Preparedness community and potential of liquefaction due to earthquake occurred in the village baturetno sub-district banguntapan yogyakarta regency
Authors: Kinthen N , Pahleviannur M R , Sari H N , Rizkyandri R , Arozaq M , Suharjo
Published: April 2021

Baturetno village was one of the areas affected by the Yogyakarta earthquake on May 27, 2006 which left thousands dead, seriously injured, and destroyed buildings on the ground. The condition of the Bantul Regency area with hilly nature which has a labile soil structure causes the soil to become unstable and to see the geological conditions, Baturetno Village, Banguntapan District, Bantul Regency has the potential to be threatened by liquefaction caused by the earthquake. The purpose of this study was to identify: (1) the level of knowledge of the people in Baturetno Village regarding liquefaction and earthquakes and (2) the level of community preparedness in Baturetno Village regarding liquefaction and earthquakes. The research method used is a quantitative method with a descriptive approach. The population in this study were all people in Baturetno Village as many as 14,345 people, while the study sample was 99 residents with sampling techniques using systematic stratified sampling techniques. Based on the results of the study it can be concluded that: (1) the level of knowledge of the Baturetno Village community regarding liquefaction and earthquakes is less readily available for total realty with an index value of 40-50, which means that the attitude is not ready and the percentage 57%. Meanwhile, (2) the level of community preparedness is known to be ready to face liquefaction due to earthquakes and mobilization from the community stating that they are prepared in terms of preparedness of 70%, which means that the community is responsive and alert to natural disasters. In accordance with what has been described above, the need for efforts to increase the level of knowledge and preparedness in the face of liquefaction and earthquakes.
Valorising landscape: taking opportunities from drought to ecotourism high-end products
Authors: Haryanti N
Published: April 2021

Naturally, area of Gunungkidul is dominated by unique hilly karst landscape. The area is poor in resources. Quality of soil is low and lack of sufficient water during dry session. Most of inhabitants work in agricultural sector, either as peasant with less than 0.5 Ha or pair workers. Physical characteristic of the area allows only certain species of agricultural crops can be cultivated. A factor for high poverty rate status, it is because limited alternatives for farm diversity are available. Recent phenomenon on climate variability is another threat to rural living, farmers have pushed to adapt to range of weather that most likely leads to significant social and economic long-lasting problems. This paper is aimed to expose gradual shift in the rural setting. It was based on the survey and depth interview data, and was analyzed qualitatively. Agriculture will not provide sufficient income any longer for daily needs. Therefore, despite doing daily farm activities, some farmers have irregular forms to get additional income. They work in construction, home industries, or tourism sectors. Following national trend, growing interests to developing beneficial ways of living in ecotourism sector have been started. This trend is supported by recent exploration to many potential underground caves. Since then, many tourist management groups have grown in the village basis, selling cave-tubing experiences as recreational activities. Ecotourism sector offers sustainable income and valuable alternative out of poverty to many local people. Supported by development of industry 4.0, a powerful means seamlessly connecting people and information, local assets are promoted easily and quickly allowing the most vulnerable groups to escape from severe disaster like drought.
Pentahelix synergy in realizing ecovillage values in the Cijalingan village community of Cicantayan Sukabumi district
Authors: Hidayat M. , Rozak R. W. A. , Kembara M. D. , Baihaki E.
Published: April 2021

In 21st century, people must be able to think HOTS (Higher Order Thinking Skills). HOTS thinking greatly influences the way of life of the community, especially in developing the region. The central government has supported the community to build independent village by giving village funds. However, this has not been going well because the use of village funds has not been maximized. The use of Pentahelix model is an effort to reach an independent village with the concept of ecovillage. In the study used a descriptive qualitative approach with the main data interview and direct observation. Based on the results of interviews shows that the use of village funds only focus on renovation and development and improvement of village infrastructure. Observation results show that Cijalingan Village has the potential become a tourism village with its natural panorama. The people of Cijalingan Village have handicrafts in the form of sandals. It is very supportive to side with the concept of a tourism village, so that in the end it is able to become an independent village.
Temperature Dependent Minerals as a Tool to Prove High Temperature of a Blind Geothermal System. Case Study: Well “X” at Java Island of Indonesia
Authors: Utomo Darren A. , Abiyudo Rizal , Saputra Isto J. , Irfan Riki , Archady Dalmathias
Published: April 2021

Geology and mineral alteration are studied to review the equilibrium of blind geothermal system in Java Island, Indonesia. The “X” well is a slim hole well that has been drilled to 2000 mMD. Indication of high-temperature geothermal system is observed by pressure-temperature survey and mineral alteration recovered by full core from surface to bottom (2000 mMD). Geologically, this geothermal prospect is situated on a caldera system with the volcanism started since the Lower Pleistocene related to the early stages of magmatic activity of the modern Sunda arc. Multiple eruptions associated with the pre-caldera, syn-caldera, and post-caldera volcanism deployed rock formation which are consisted of andesitic lava series, volcanic breccia, and pyroclastic. Based on the study of mineral alteration, three hydrothermal alteration zones are defined from temperature-dependent minerals to predict reservoir temperatures, smectite zone (T<180°C) from the surface down to 1200 mMD, transition zone (T = 180-220°C) down to 1383 mMD, and illite zone (T>220°C) down to 2000 mMD. Moreover, the hydrothermal alteration zone is mainly used to estimate the depth of clay cap, transition, and reservoir zone for a future appraisal well. Correlating the temperatures and hydrothermal alteration zones could help in proving a high-temperature geothermal system especially in a blind geothermal system.
Geology Assessment of Permeability Distribution in Silangkitang Geothermal Field, North Sumatra, Indonesia
Authors: Satya Drestanta Yudha , Suryantini  , Astra Doddy
Published: April 2021

The Silangkitang (SIL) geothermal system is a fault-controlled and liquid-dominated reservoir associated to a deep heat source. Geology data from recent development drilling and reservoir monitoring demonstrated that the high permeability is concentrated within zone between two strands of Great Sumatra Fault (GSF). These faults are major dextral strike slip system that cross the entire length of Sumatra Island. The fault distribution has been defined by integration and interpretation of tectonic geomorphology, surface geology, and well geology. The highest permeability is controlled by faults and fractures associated with localized releasing steps within west of main Tor Sibohi Fault (TSF). This paper outlines the indication of high permeability zone based on recent geology evaluation outcome.
Cased-hole Gamma Ray Log Assessment and Application to Support Reservoir Characterization at Salak Field in Indonesia
Authors: Putra Fanji Junanda , Talita Ananyamatya Bella
Published: April 2021

Gamma Ray (GR) logging is a common wireline activity conducted in the oil & gas industry to identify sand and shale bodies. In the geothermal industry, studies have shown that the GR count has a close correlation with the silica content of rocks. Generally, rocks with high silica content (i.e., felsic) will have relatively higher GR count than rocks with low silica content (i.e., mafic). In the reservoir section of geothermal field, very few (to almost none) rocks cuttings are obtained because mud loss normally occurred. Therefore, another dataset is required to identify lithologies/formations and GR log is one of the continuous datasets in the reservoir hole section that may help to solve this problem. At Salak, open-hole GR logs have been obtained during well completion, but these are few compared to the hundreds of wells drilled. In 2017, the GR tool was included in the bottom-hole assembly (BHA) of wireline surveys at Salak, such as Pressure-Temperature (PT) and Pressure-Temperature-Spinner (PTS) and thus, providing an opportunity to collect infill cased-hole GR data. Evaluation of the cased-hole GR logs indicated good quality and correlation with open-hole GR logs and used to support lithology/formation interpretation, especially for the Rhyodacite Marker (RDM) and Marine Sediments and Volcaniclastic (MSV) Formations as both the formations have distinct GR response compared to other formations at Salak.
Scaling in Two-Phase Pipeline (Study Case: Sarulla Geothermal Field)
Authors: Siahaan Mona Natalia , Andhika Muhamad , Berutu Sahat , Smith Alexander
Published: April 2021

Sarulla geothermal field is operating 330MW with the combined cycle plant in Indonesia. During the operation of the facilities, there have been many challenges. One of the most prominent obstacles is scaling in the surface facility. Scale deposition is a common problem in geothermal surface facilities. Temperature changes affect thermodynamics reaction which leads to scaling. Precipitation of silica reduces the diameter of the pipe which also reduces the flow rate in the pipeline. Furthermore, the generation will decrease as a result of decreasing the flow rate. In most cases, scale precipitation occurs downstream which has decreased temperature. This field is experiencing scaling in the two-phase environment although it has a higher temperature and in undersaturated condition. This is caused by the mixing of different pH levels of geothermal fluid into the header. In this case, low pH fluid mixed with neutral fluid which also has high silica content. This study investigates and discusses this phenomenon and types of scaling. The result could be used to understand the precipitation process of silica and how to prevent this from happening in the future.
Black Material Deposition in Surface Facilities During Commissioning in Muara Laboh Geothermal Field
Authors: Azka Ghilman , Alfiady  , Azis Herwin , Aulia Nurul
Published: April 2021

Muara Laboh geothermal field is located in West Sumatra, Indonesia. The installed capacity is 80-85 MWe and already accomplished the Commercial Operation Date (COD) in December 2019. Prior to COD, several programs were conducted: pre-commissioning and commissioning programs. During these activities, some findings were encountered and one of the major findings was the black material deposit at several spots. The black material found from HP separator drain, condensate drain port and then ended up beneath the cooling tower basin. Based on the laboratory analysis, the SEM-EDX data shows that the material dominated by magnetite (Fe-Ox) and pyrite (FeS2) for the strainer sample. Meanwhile, the sample from HP separator contains some amount of silica, Arsenopyrite, anhydrite, and carbon. The occurrence of Fe-Ox might indicate the source of the black material coming from industrial goods, which caused by steam flow activity during the pre-com and commissioning program. Thus, the fact that no black material found during well testing from all wells also supports the theory.
Volcanostratigraphy Study of Slamet Volcano and the Implication to Its Early Stage of Geothermal Exploration
Authors: Assiddiqy Muhamad Hasbi , Gati Rai , Sibarani Betseba , Suryantini
Published: April 2021

The application of volcanostratigraphy has been broadly used on many early stages of geothermal exploration. The method is simple yet powerful to give a preliminary suspicion on geothermal potential before a field survey. By combining contour analysis in certain scale (1:50,000 and 1:100,000) such as ridge and river pattern with the stratigraphic analysis of volcanic product the volcanostratigraphy units are determined. In this study, the volcanostratigraphy units were assessed using geothermal potential evaluation scheme for a stratovolcano to determine the potential of a geothermal green field.As the object of the study, a quarternary stratovolcano of Slamet Volcanic Complex in Central Java region was analyzed. Eight volcanostratigraphic units were determined in Slamet Volcanic Complex area and its surrounding, including six crowns and two hummocks. In addition, the hydrothermal fluid from several manifestations within the Slamet Volcanic Complex area (warm springs) were analysed to characterize the potentials of Slamet Volcanic Complex Region. Based on these determined volcanostratigraphy units,the occurrence of hydrothermal manifestation within the defined volcanostratigraphy units, the result of hydrothermal fluid analysis, and the criteria matching to the potential evaluation scheme for stratovolcano, the Slamet Volcanic Complex was categorized as potentially beneficial to be surveyed in detail. In such system, the volcanostratigraphy method is relatively simple and reliable to be applied since the volcanic evolution sequences data are accessible.
Geothermal Prospect Review in the Western Part of Salak Volcano, West Java, Indonesia
Authors: Aprilina Nur Vita , Golla Glenn U. , Kusumah Yudi Indra , Suryantini
Published: April 2021

The Ertankian Geothermal Prospect is located in the southern area of Bogor District, West Java, Indonesia. From 1982 through the end of 1983, Unocal Geothermal of Indonesia, Ltd. (UGI) conducted extensive geological, geochemical, and geophysical surveys that outlined Ertankian as a potential geothermal field on the flanks of the Salak Volcano. This volcano forms the north-eastern part of the Salak-Perbakti-Gagak Volcanic Massif, which consists of Upper Pleistocene to Recent stratovolcanoes, parasitic vents, and phreatomagmatic craters. The exploration survey included, magnetotelluric and gravity surveys, water geochemistry, thermal manifestation gas, ion, and isotope analyses, and geological, photo-geological interpretation, and photogrammetry interpretation. Kawah Ertankian is a vigorous fumarole area with numerous superheated and boiling steam vents, boiling acid sulfate hot springs, and large areas of acid-altered ground. Elemental sulfur is common around many of the vents. Steam from the Ertankian Fumaroles contains 7 mol% H2S and the maximum reservoir temperature obtained from the NAH-CO2 gas geothermometer was 525°F. The Ertankian Hot Springs have acid sulfate character and yield little information about the underlying hydrothermal system. Bicarbonate chloride warm springs occur on the northern flanks of the Salak Volcano at northwest and northeast locations and interpreted as the outflow product of Ertankian Geothermal System. Extensive areas of low resistivity are distributed across most of the Ertankian Geothermal Prospects. Low resistivity zones are observed around the Kawah Ertankian thermal manifestation complex and broaden to the far northwestern warm spring and Gunung Perbakti in the southwest. The shallowest base of the conductor is observed in the area near Kawah Ertankian and probably extends towards the northwest in the Alpha-19 well area. Towards the south and southwest, a significant deepening of base of the clay cap is observed. The observed resistivity trend coincides with and parallels to the NW-SE South and North Ertankian Faults, which may be the outflow pathway of the hydrothermal system. The lower rock conductance values and deepening of the clay cap base toward the southwest indicate a lower possibility of connection to the main Salak geothermal system. Considering the geological, geochemical, and geophysical data, the Ertankian Geothermal Prospect is presumed to be an encouraging area for further studies.